Flinn, Ian W.

Abstract Introduction: Bruton tyrosine kinase inhibitors (BTKi) have revolutionized the treatment of chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL) and certain B-cell neoplasms. However, resistance to BTKi develops primarily through mutations at the cysteine binding site (C481) or PLCγ2 mutations. MK-1026 (formerly ARQ-531) is a non-covalent, potent inhibitor of both wild type and C481- mutated BTK. In the phase 1/2 dose escalation and dose expansion study NCT03162536, the preliminary recommended phase 2 dose (RP2D) of MK-1026 was determined to be 65 mg once daily. The efficacy and safety of MK-1026 in participants with CLL/SLL and B-cell non-Hodgkin lymphoma (NHL) were also evaluated at a higher dose during the dose expansion phase. Methods: In this open-label, single-arm phase 2 study, 9 expansion cohorts were initiated following determination of preliminary MK-1026 RP2D. Approximately 10-25 eligible participants were enrolled into Cohort A (relapsed/refractory (r/r) CLL/SLL, with ≥2 prior therapies including covalent BTKi, with documented C481 mutation), Cohort B (r/r CLL/SLL progressed on/intolerant to a BTKi, with ≥2 prior therapies without C481 mutation), Cohort C (participants with Richter transformation [RT] with ≥1 prior therapy), Cohort D-H (participants with follicular lymphoma (FL), mantle cell lymphoma (MCL), marginal zone lymphoma (MZL), high-grade B cell lymphoma (BCL) with known MYC, BCL-2 or BCL-6 translocations, and Waldenström macroglobulinemia (WM), respectively, who received ≥2 prior therapies), Cohort I (food effect cohort including participants with B-cell NHL, CLL/SLL, and WM). Treatment continued until unacceptable toxicity, clinical or radiological progression, participant/physician withdrawal. Primary endpoint was overall response rate (per iwCLL criteria, by investigator) for participants with CLL/SLL. Secondary endpoints included duration of response and safety and tolerability. The data cut-off date for this analysis was April 7, 2021. Results: Among 118 participants enrolled, 44 had B-cell NHL (including 6 with DLBCL, 11 with FL, 3 with high-grade BCL, 6 with MCL, 2 with MZL, 16 with RT), 68 CLL/SLL, and 4 WM. Of these, 94 (79.6%) were treated at the preliminary RP2D, including 51 (54.3%) participants with CLL/SLL. Participants with CLL/SLL had a median (range) number of prior therapies of 4 (1-18), 43 (84%) had prior BTKi therapy, 12 (23%) had del17p, 26 (51%) had IGHV unmutated status, and 32 (63%) had C481S BTK mutation. At data cut-off, median (range) follow-up was 4.56 months (0.1-26.7) for all treated participants. ORR was 57.9% (N = 22 of 38; 1 CR, 21 PR/PRL) per iwCLL criteria in the efficacy evaluable population of participants with CLL/SLL treated at preliminary RP2D. The median duration of response in these participants was not estimable [NE] (range, 8.3 months-NE). At data cut-off, the median duration of treatment exposure was 3.2 months (range, 0-35.9). Among all treated participants, 114 (97%) had a treatment-emergent adverse event (TEAE), with 78 (66%) having a drug-related TEAE, and 9 (8%) having a drug-related TEAE that led to discontinuation. Common TEAEs (≥ 20%) included fatigue (33%), constipation (31%), dysgeusia (28%), cough (25%), nausea (25%), pyrexia (25%), dizziness (23%), hypertension (23%), peripheral edema (22%), arthralgia (20%), and diarrhea (21%). Grade ≥3 TEAEs occurred in 80 (68%) participants. Grade 5 TEAEs occurred in 7 (6%) participants and included death following disease progression in 3 (3%), sepsis 1 (1%), dyspnea 1 (1%), and respiratory failure 2 (2%) participants. Common drug-related TEAEs (≥10%) included dysgeusia (15%), nausea (11%), fatigue (11%), and decreased neutrophil count (10%). Grade 3-4 drug-related TEAEs occurred in 31 (26%) participants. No drug-related TEAEs led to death. Conclusion: MK-1026 has promising antitumor activity with a manageable safety profile in participants with CLL/SLL exposed to multiple lines of therapy, including in those who had progression of disease on prior covalent BTKi. Further evaluation of MK-1026 in B-cell malignancies is ongoing. Disclosures Woyach: AbbVie Inc, ArQule Inc, Janssen Biotech Inc, AstraZeneca, Beigene: Other: Advisory Committee; AbbVie Inc, ArQule Inc, AstraZeneca Pharmaceuticals LP, Janssen Biotech Inc, Pharmacyclics LLC, an AbbVie Company,: Consultancy; AbbVie Inc, Loxo Oncology Inc, a wholly owned subsidiary of Eli Lilly & Company: Research Funding; Gilead Sciences Inc: Other: Data & Safety. Flinn: Verastem: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Genentech: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; IGM Biosciences: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Gilead Sciences: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Juno Therapeutics: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Yingli Pharmaceuticals: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Constellation Pharmaceuticals: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Loxo: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Kite, a Gilead Company: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Novartis: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; AbbVie: Consultancy, Other: All Consultancy and Research Funding payments made to Sarah Cannon Research Institute, Research Funding; AstraZeneca: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Great Point Partners: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Iksuda Therapeutics: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; BeiGene: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Pharmacyclics LLC, an AbbVie Company: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Forty Seven: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Calithera Biosciences: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Roche: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Unum Therapeutics: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; MorphoSys: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Merck: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; TG Therapeutics: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Janssen: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Teva: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Takeda: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Seagen: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Karyopharm Therapeutics: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Celgene: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Incyte: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Infinity Pharmaceuticals: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Agios: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Curis: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Acerta Pharma: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; ArQule: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Pfizer: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Forma Therapeutics: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Nurix Therapeutics: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Portola Pharmaceuticals: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Rhizen Pharmaceuticals: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Trillium Therapeutics: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Triphase Research & Development Corp.: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Century Therapeutics: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Hutchison MediPharma: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Vincerx Pharma: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Sarah Cannon Research Institute: Current Employment; Servier Pharmaceuticals: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Yingli Pharmaceuticals: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Seagen: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Servier Pharmaceuticals: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Unum Therapeutics: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute, Research Funding; Johnson & Johnson: Current holder of individual stocks in a privately-held company; Seattle Genetics: Research Funding. Awan: Verastem: Consultancy; Incyte: Consultancy; Dava Oncology: Consultancy; MEI Pharma: Consultancy; Beigene: Consultancy; Celgene: Consultancy; Johnson and Johnson: Consultancy; Karyopharm: Consultancy; Kite pharma: Consultancy; Gilead sciences: Consultancy; Pharmacyclics: Consultancy; Janssen: Consultancy; BMS: Consultancy; Merck: Consultancy; Cardinal Health: Consultancy; ADCT therapeutics: Consultancy; Abbvie: Consultancy; Astrazeneca: Consultancy; Genentech: Consultancy. Eradat: AstraZeneca: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Abbvie: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Beigene: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Incyte: Speakers Bureau; Juno: Research Funding; Kite: Research Funding; Genentech: Research Funding. Brander: Pfizer: Consultancy, Other: Biosimilars outcomes research panel; Juno Therapeutics/Celgene/Bristol Myers Squibb: Research Funding; ArQule: Research Funding; Ascentage: Research Funding; AstraZeneca: Research Funding; BeiGene: Research Funding; DTRM: Research Funding; Pharmacyclics LLC, an AbbVie Company: Consultancy, Research Funding; MEI Pharma: Research Funding; TG Therapeutics: Consultancy, Research Funding; Novartis: Research Funding; LOXO: Research Funding; Verastem: Consultancy; ArQule/Merck: Consultancy; Genentech: Consultancy, Research Funding; NCCN: Other: panel member; AbbVie: Consultancy, Other: informCLL registry steering committee, Research Funding. Parikh: Pharmacyclics, MorphoSys, Janssen, AstraZeneca, TG Therapeutics, Bristol Myers Squibb, Merck, AbbVie, and Ascentage Pharma: Research Funding; Pharmacyclics, AstraZeneca, Genentech, Gilead, GlaxoSmithKline, Verastem Oncology, and AbbVie: Membership on an entity's Board of Directors or advisory committees. Phillips: BMS: Consultancy, Research Funding; AstraZeneca: Consultancy; Incyte: Consultancy, Other: received travel expenses from Incyte, Research Funding; Genentech: Membership on an entity's Board of Directors or advisory committees, Research Funding; AbbVie: Consultancy, Research Funding; ADCT, BeiGene, Bristol Myers Squibb, Cardinal Health, Incyte, Karyopharm, Morphosys, Pharmacyclics, Seattle Genetics: Consultancy; Bayer: Consultancy, Research Funding. Reddy: Merck & Co., Inc.: Current Employment. Farooqui: Merck & Co., Inc.: Current Employment, Other: Current Stockholder. Byrd: Vincerx Pharmaceuticals: Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Novartis, Trillium, Astellas, AstraZeneca, Pharmacyclics, Syndax: Consultancy, Honoraria; Newave: Membership on an entity's Board of Directors or advisory committees. Stephens: CSL Behring: Consultancy; Innate Pharma: Membership on an entity's Board of Directors or advisory committees; Beigene: Membership on an entity's Board of Directors or advisory committees; Epizyme: Membership on an entity's Board of Directors or advisory committees; TG Therapeutics: Membership on an entity's Board of Directors or advisory committees; Adaptive: Membership on an entity's Board of Directors or advisory committees; Arqule: Research Funding; Mingsight: Research Funding; JUNO: Research Funding; Novartis: Research Funding; Abbvie: Consultancy; AstraZeneca: Consultancy; Celgene: Consultancy; Karyopharm: Membership on an entity's Board of Directors or advisory committees, Research Funding.

Abstract Background CD47 is an innate immune checkpoint that binds signal regulatory protein alpha (SIRPα) and delivers a "don't eat me" signal to suppress macrophage phagocytosis. Overexpression of CD47 can allow tumor cells to escape immune surveillance. TTI-621 (SIRPαFc) is a fusion protein consisting of the CD47 binding domain of human SIRPα linked to the Fc region of human IgG1, designed to enhance phagocytosis and antitumor activity by blocking the CD47-SIRPα interaction between malignant cells and macrophages, and engaging Fcγ receptors. Here we report updates from the dose optimization part of the first-in-human study of TTI-621 (NCT02663518), testing dose levels between 0.5-2.0 mg/kg in patients with cutaneous T-cell lymphoma (CTCL). Methods This study has been conducted in 4 parts. Part 1 tested increasing weekly intravenous doses of TTI-621 based on 3+3 escalation. The maximum tolerated dose was initially determined to be 0.2 mg/kg based on dose limiting toxicity (DLT) of thrombocytopenia [defined as Grade (Gr) 4 of any duration]. Expanded testing followed in patients with hematologic malignancies. In Part 2, most patients received 0.2 mg/kg; however, based on investigator discretion, a subset of patients received escalating doses up to 0.5 mg/kg. In Part 3, patients with T-cell lymphomas received stepwise dose escalations from 0.2 to 0.5 mg/kg over the first 5−8 weeks. Part 4 (dose optimization) of this study, is currently ongoing with weekly TTI-621 treatment escalating in a standard 3+3 manner through 5 planned dose levels including 0.5, 0.7, 1, 1.4, and 2 mg/kg. Dose optimization is being assessed in patients with CTCL. The DLT criteria was modified to require Gr 4 thrombocytopenia lasting >72 hours. Safety monitoring includes weekly clinical laboratories and assessments of adverse events (AEs) per CTCAE v 4.03. Blood samples are obtained for pharmacokinetics and disease assessments are performed per Olsen's criteria. Results In Parts 1−3 (n=214), the most common related AEs were infusion-related reaction (IRR, 43%; 3% Gr ≥3), thrombocytopenia (30%; 22% Gr ≥3), chills (22%; 0% Gr ≥3), and fatigue (16%; 1% Gr ≥3). Objective responses to single agent TTI-621 were achieved in 14/71 (20%) NHL pts including CTCL (n=42, 1 CR, 7 PRs), PTCL (n=22, 2 CRs, 2 PRs) and DLBCL (n=7, 1 CR, 1 PR). In Part 4 as of April 12, 2021, 24 patients (17M/7F, median age 65 years) have enrolled into the 5 dose cohorts including 9 patients in the 2.0 mg/kg dose level. CTCL subtypes enrolled include mycosis fungoides (MF, n=18) and Sézary syndrome (SS, n=6). Disease stage was advanced (≥IIB) in 16 (67%) patients and a median of 3 (range 1−12) prior systemic therapies were received. Related AEs occurred in 19 (79%; 33% Gr ≥3) patients including infusion-related reaction (IRR, 50%; 13% Gr ≥3), thrombocytopenia (33%; 25% Gr ≥3), and neutropenia and headache, (13%, 0% Gr ≥3, each). Thrombocytopenia generally occurred on dosing days, and typically recovered within 2-4 days. A total of 15 IRRs have occurred in 12 (50%) patients at all doses levels. Most IRRs occurred during initial infusions only and typically resolved within the day of occurrence. The occurrence of Gr 3 IRRs prompted the addition of corticosteroids to the pre-medication regimen which largely prevent their occurrence. Aside from IRRs and thrombocytopenia which was manageable, AEs were predominantly Gr ≤2. Pharmacokinetic results reveal continued dose-dependent increases in exposure. Objective responses have been observed in 4 of 20 (20%) evaluable patients to date, including 3 partial responses in 14 patients with MF and 1 complete response in 6 patients with SS. Treatment is ongoing in the patient who achieved CR (10+ months) and in 2 of 3 patients who achieved PR (3 and 4 months). A third patient who achieved PR elected to discontinue study treatment at 5 months to pursue allogeneic stem and progenitor cell transplantation. Conclusions Preliminary results from dose optimization testing indicate that weekly infusions of TTI-621 up to 2 mg/kg are generally well tolerated. In Part 4, an overall response rate of 20% has been observed thus far in patients with CTCL. Testing of TTI-621 in alternative dosing schedules is in progress. With demonstrated good tolerability and robust single agent antitumor activity in heavily pre-treated patients, additional testing of TTI-621 beyond relapsed/refractory lymphoma has started. Disclosures Horwitz: Affimed: Research Funding; ADC Therapeutics, Affimed, Aileron, Celgene, Daiichi Sankyo, Forty Seven, Inc., Kyowa Hakko Kirin, Millennium /Takeda, Seattle Genetics, Trillium Therapeutics, and Verastem/SecuraBio.: Consultancy, Research Funding; Acrotech Biopharma, Affimed, ADC Therapeutics, Astex, Merck, Portola Pharma, C4 Therapeutics, Celgene, Janssen, Kura Oncology, Kyowa Hakko Kirin, Myeloid Therapeutics, ONO Pharmaceuticals, Seattle Genetics, Shoreline Biosciences, Inc, Takeda, Trillium Th: Consultancy; Aileron: Research Funding; Celgene: Research Funding; C4 Therapeutics: Consultancy; Crispr Therapeutics: Research Funding; Daiichi Sankyo: Research Funding; Forty Seven, Inc.: Research Funding; Kura Oncology: Consultancy; Kyowa Hakko Kirin: Consultancy, Research Funding; Millennium/Takeda: Research Funding; Myeloid Therapeutics: Consultancy; ONO Pharmaceuticals: Consultancy; Seattle Genetics: Consultancy, Research Funding; Secura Bio: Consultancy; Shoreline Biosciences, Inc.: Consultancy; Takeda: Consultancy; Trillium Therapeutics: Consultancy, Research Funding; Tubulis: Consultancy; Verastem/Securabio: Research Funding. Foran: pfizer: Honoraria; novartis: Honoraria; servier: Honoraria; bms: Honoraria; revolution medicine: Honoraria; taiho: Honoraria; syros: Honoraria; sanofi aventis: Honoraria; certara: Honoraria; gamida: Honoraria; OncLive: Honoraria; abbvie: Research Funding; boehringer ingelheim: Research Funding; takeda: Research Funding; trillium: Research Funding; aptose: Research Funding; actinium: Research Funding; kura: Research Funding; h3bioscience: Research Funding; aprea: Research Funding; sellas: Research Funding; stemline: Research Funding. Lue: Epizyme: Consultancy; TG Therapeutics: Consultancy; Kymera Therapeutics: Research Funding; AstraZeneca: Speakers Bureau; Kura Oncology: Consultancy. Sawas: Affimed: Research Funding; Roche: Current equity holder in publicly-traded company; Flat Iron Health: Current Employment; Seattle Genetics: Honoraria; Acrotech: Honoraria; Daiichi-Sankyo: Speakers Bureau; Seattle Genetics: Speakers Bureau; Gilead: Speakers Bureau. Feldman: Alexion, AstraZeneca Rare Disease: Honoraria, Other: Study investigator. Sokol: Kyowa-Kirin: Membership on an entity's Board of Directors or advisory committees; Dren Bio: Membership on an entity's Board of Directors or advisory committees. Mei: Janssen: Honoraria; EUSA: Honoraria; TG Therapeutics: Research Funding; Epizyme: Research Funding; BMS: Research Funding; Morphosys: Research Funding; Beigene: Research Funding. Flinn: AbbVie: Consultancy, Other: All Consultancy and Research Funding payments made to Sarah Cannon Research Institute, Research Funding; AstraZeneca: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; BeiGene: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Genentech: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Gilead Sciences: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Great Point Partners: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Iksuda Therapeutics: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Janssen: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Juno Therapeutics: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Kite, a Gilead Company: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; MorphoSys: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Nurix Therapeutics: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Pharmacyclics LLC, an AbbVie Company: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Roche: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Seagen: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Takeda: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; TG Therapeutics: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Unum Therapeutics: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Verastem: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Yingli Pharmaceuticals: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Acerta Pharma: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Agios: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; ArQule: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Calithera Biosciences: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Celgene: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Constellation Pharmaceuticals: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Curis: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Forma Therapeutics: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Forty Seven: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; IGM Biosciences: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Incyte: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Infinity Pharmaceuticals: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Karyopharm Therapeutics: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Loxo: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Merck: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Novartis: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Pfizer: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Portola Pharmaceuticals: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Rhizen Pharmaceuticals: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Teva: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Trillium Therapeutics: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Triphase Research & Development Corp.: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Century Therapeutics: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Hutchison MediPharma: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Vincerx Pharma: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Sarah Cannon Research Institute: Current Employment; Servier Pharmaceuticals: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Yingli Pharmaceuticals: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Seagen: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Servier Pharmaceuticals: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Unum Therapeutics: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute, Research Funding; Johnson & Johnson: Current holder of individual stocks in a privately-held company; Seattle Genetics: Research Funding. Villa: Janssen: Honoraria; Roche: Honoraria; Lundbeck: Honoraria; Celgene: Honoraria; Seattle Genetics: Honoraria; AbbVie: Honoraria; AstraZeneca: Honoraria; Gilead: Honoraria; NanoString Technologies: Honoraria. Percival: Pfizer: Research Funding; Abbvie: Research Funding; Biosight: Research Funding; BMS/Celgene: Research Funding; Cardiff Oncology: Research Funding; Glycomimetics: Research Funding; Nohla Therapeutics: Research Funding; Oscotec: Research Funding; Trillium: Research Funding. Savage: Seattle Genetics: Consultancy, Honoraria; BMS: Consultancy, Honoraria, Other: Institutional clinical trial funding; Merck: Consultancy, Honoraria, Other: Institutional clinical trial funding; AbbVie: Consultancy, Honoraria; Astra-Zeneca: Consultancy, Honoraria; Servier: Consultancy, Honoraria; Roche: Research Funding; Takeda: Other: Institutional clinical trial funding; Beigene: Other: Institutional clinical trial funding; Genentech: Research Funding. Diefenbach: Genentech, Inc./ F. Hoffmann-La Roche Ltd: Consultancy, Honoraria, Research Funding; Seattle Genetics: Consultancy, Honoraria, Research Funding; Bristol-Myers Squibb: Consultancy, Honoraria, Research Funding; Merck Sharp & Dohme: Consultancy, Honoraria, Research Funding; Morphosys: Consultancy, Honoraria, Research Funding; Janssen: Consultancy, Honoraria, Research Funding; MEI: Consultancy, Research Funding; Gilead: Current equity holder in publicly-traded company; IMab: Research Funding; Celgene: Research Funding; Trillium: Research Funding; Incyte: Research Funding; AbbVie: Research Funding; Perlmutter Cancer Center at NYU Langone Health: Current Employment; IGM Biosciences: Research Funding. Kim: Kyowa Kirin: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Innate: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Corvus: Membership on an entity's Board of Directors or advisory committees, Research Funding; Trillium: Research Funding; Galderma: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Elorac: Research Funding; Portola: Membership on an entity's Board of Directors or advisory committees, Research Funding; Soligenix: Research Funding; Eisai: Research Funding; CRISPR: Research Funding; Regeneron: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Sanofi: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Mundipharma: Honoraria, Membership on an entity's Board of Directors or advisory committees; Secura Bio: Honoraria, Membership on an entity's Board of Directors or advisory committees; Alexion, AstraZeneca Rare Disease: Other: Study investigator; Merck: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Takeda: Consultancy, Membership on an entity's Board of Directors or advisory committees; Seattle Genetics: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Horizon: Research Funding. Lin: Trillium Therapeutics: Current Employment, Current holder of stock options in a privately-held company. Catalano: Trillium Therapeutics: Current Employment, Current holder of stock options in a privately-held company. Petrova: Trillium Therapeutics: Current Employment, Current holder of stock options in a privately-held company. Uger: Trillium Therapeutics: Current Employment, Current holder of stock options in a privately-held company. Molloy: Trillium Therapeutics: Current Employment, Current holder of stock options in a privately-held company. Large: Trillium Therapeutics: Current Employment, Current holder of stock options in a privately-held company. Bruns: Trillium Therapeutics: Current Employment, Current holder of stock options in a privately-held company. Ansell: Bristol Myers Squibb, ADC Therapeutics, Seattle Genetics, Regeneron, Affimed, AI Therapeutics, Pfizer, Trillium and Takeda: Research Funding.

Abstract Background: Axi-cel, an autologous anti-CD19 chimeric antigen receptor (CAR) T-cell therapy, is approved for the treatment of pts with relapsed/refractory LBCL with ≥ 2 prior systemic therapies. In the 2-year analysis of ZUMA-1 (NCT02348216), the multicenter, single-arm phase 1/2 study evaluating axi-cel in pts with refractory LBCL, the objective response rate (ORR) was 83%, including a complete response (CR) rate of 58%; 39% of pts had ongoing response with a median follow-up of 27.1 months (Locke et al. Lancet Oncol. 2019). EFS is emerging as a robust surrogate endpoint for OS in hematologic malignancies. A recent systematic analysis demonstrated a linear correlation between EFS and OS in pts with diffuse LBCL after first-line immunochemotherapy (Zhu et al. Leukemia. 2020). Here, we report updated survival findings from the phase 2 portion of ZUMA-1 after 4 years of follow-up, including an evaluation of the association of OS with EFS. Methods: Eligible pts had refractory LBCL (diffuse LBCL, primary mediastinal B cell lymphoma, transformed follicular lymphoma). After leukapheresis at enrollment, pts received low-dose conditioning chemotherapy (fludarabine and cyclophosphamide) followed by a target dose of 2×10 6 anti-CD19 CAR T cells/kg (Neelapu et al. N Engl J Med. 2017). The primary endpoint was ORR, with the first response assessment occurring 4 weeks following infusion. Additional endpoints included safety and translational evaluations. An exploratory analysis of OS by EFS at 12 and 24 months was performed. EFS was defined as the time from axi-cel infusion until disease progression, initiation of new lymphoma therapy (excluding stem cell transplant), or death from any cause. Comparisons of OS by EFS outcomes were analyzed via Kaplan-Meier estimates. Results: Of 111 enrolled pts, axi-cel was administered to 101 pts. As of August 11, 2020, median follow-up was 51.1 months. With over 4 years of follow-up, median OS was 25.8 months, and the 4-year OS rate was 44%. Median EFS in pts treated with axi-cel was 5.7 months, with a 12-month EFS rate of 43% (95% CI, 33-52) and a 24-month EFS rate of 38% (95% CI, 28-47). In pts with an EFS event by Month 12 (EFS12; n=57) vs those without EFS12 (n=44), 4-year OS rates were 7% (95% CI, 2-16) vs 91% (95% CI, 78-97), respectively. Among the 17 pts with EFS12 who were alive at Month 12, 13 (76%) died by Month 48, while among the 44 pts alive at Month 12 without EFS12, 4 (9%) died by Month 48. In pts with an EFS event by Month 24 (EFS24; n=62) vs those without EFS24 (n=39), 4-year OS rates were 13% (95% CI, 6-23) vs 92% (95% CI, 78-98), respectively. Among the 12 pts with EFS24 who were alive at Month 24, 4 (33%) died by Month 48, while among the 39 pts alive at Month 24 without EFS24, 3 (8%) died by Month 48. Since the 2-year analysis (Locke et al. Lancet Oncol. 2019), there have been no new safety signals reported, including no new serious adverse events, no axi-cel-related secondary malignancy, and no confirmed cases of replication-competent retrovirus. Overall, 26 pts received subsequent anti-cancer therapy; median time to next therapy was 8.7 months (range, 0.3 - 53.8). Immunoglobulin therapy was administered to 38 (38%) pts. Two pts in axi-cel-induced remission received allogeneic stem cell transplant; 1 pt was in CR and 1 pt was in partial response. Among treated pts, 58 (57%) have died, primarily due to progressive disease (46%; n=46), followed by other reasons (7%; n=7), adverse events (4%; n=4), and secondary malignancy (myelodysplastic syndrome, with onset on Day 574) unrelated to axi-cel (1%; n=1). Among pts without EFS12 and without EFS24, 1 pt each (2% and 3%, respectively) died due to disease progression >24 months following axi-cel infusion; >36 months, 2 pts each (5% for both) died due to disease progression (1 pt each [2% and 3%]) and other reasons (1 pt each [2% and 3%]. One pt (2%) without EFS12 died due to disease progression between 12 and 24 months. Updated findings with ≥5 years of follow-up, including translational correlations, will be presented. Conclusion: In this long-term survival analysis of ZUMA-1 with ≥4 years of follow-up, axi-cel demonstrated longer OS in pts without EFS events at Month 12 and Month 24 vs pts with events at these timepoints. These data support the use of EFS as a surrogate endpoint for long-term OS in refractory LBCL, and the relationship between EFS and 5-year OS will be presented. Disclosures Jacobson: Nkarta: Consultancy, Honoraria; AbbVie: Consultancy, Honoraria; Kite, a Gilead Company: Consultancy, Honoraria, Other: Travel support; Axis: Speakers Bureau; Pfizer: Consultancy, Honoraria, Other: Travel support, Research Funding; Clinical Care Options: Speakers Bureau; Celgene: Consultancy, Honoraria, Other: Travel support; Precision Biosciences: Consultancy, Honoraria, Other: Travel support; Lonza: Consultancy, Honoraria, Other: Travel support; Novartis Pharmaceuticals Corporation: Consultancy, Honoraria, Other: Travel support; Humanigen: Consultancy, Honoraria, Other: Travel support. Locke: Moffitt Cancer Center: Patents & Royalties: field of cellular immunotherapy; Janssen: Consultancy, Other: Scientific Advisory Role; Gerson Lehrman Group: Consultancy; Novartis: Consultancy, Other, Research Funding; Legend Biotech: Consultancy, Other; Bluebird Bio: Consultancy, Other: Scientific Advisory Role; BMS/Celgene: Consultancy, Other: Scientific Advisory Role; Calibr: Consultancy, Other: Scientific Advisory Role; Cellular Biomedicine Group: Consultancy, Other: Scientific Advisory Role; Iovance Biotherapeutics: Consultancy, Other: Scientific Advisory Role; GammaDelta Therapeutics: Consultancy, Other: Scientific Advisory Role; Emerging Therapy Solutions: Consultancy; Takeda: Consultancy, Other; Wugen: Consultancy, Other; EcoR1: Consultancy; Umoja: Consultancy, Other; Cowen: Consultancy; Kite, a Gilead Company: Consultancy, Other: Scientific Advisory Role, Research Funding; Amgen: Consultancy, Other: Scientific Advisory Role; Allogene Therapeutics: Consultancy, Other: Scientific Advisory Role, Research Funding. Ghobadi: Atara: Consultancy; Amgen: Consultancy, Research Funding; Wugen: Consultancy; Celgene: Consultancy; Kite, a Gilead Company: Consultancy, Honoraria, Research Funding. Miklos: Pharmacyclics, Amgen, Kite, a Gilead Company, Novartis, Roche, Genentech, Becton Dickinson, Isoplexis, Miltenyi, Juno-Celgene-Bristol Myers Squibb, Allogene, Precision Biosciences, Adicet, Adaptive Biotechnologies: Research Funding; Adaptive Biotechnologies, Novartis, Juno/Celgene-BMS, Kite, a Gilead Company, Pharmacyclics-AbbVie, Janssen, Pharmacyclics, AlloGene, Precision Bioscience, Miltenyi Biotech, Adicet, Takeda: Membership on an entity's Board of Directors or advisory committees; Pharmacyclics: Patents & Royalties; Kite, a Gilead Company, Amgen, Atara, Wugen, Celgene, Novartis, Juno-Celgene-Bristol Myers Squibb, Allogene, Precision Bioscience, Adicet, Pharmacyclics, Janssen, Takeda, Adaptive Biotechnologies and Miltenyi Biotechnologies: Consultancy. Oluwole: Kite, a Gilead Company: Consultancy, Research Funding; Janssen: Consultancy; Pfizer: Consultancy; Curio Science: Consultancy. Lin: Gamida Cell: Consultancy; Legend: Consultancy; Juno: Consultancy; Takeda: Research Funding; Merck: Research Funding; Celgene: Consultancy, Research Funding; Novartis: Consultancy; Bluebird Bio: Consultancy, Research Funding; Vineti: Consultancy; Sorrento: Consultancy; Janssen: Consultancy, Research Funding; Kite, a Gilead Company: Consultancy, Research Funding. Hill: Celgene (BMS): Consultancy, Honoraria, Research Funding; Incyte/Morphysis: Consultancy, Honoraria, Research Funding; Novartis: Consultancy, Honoraria, Research Funding; Gentenech: Consultancy, Honoraria, Research Funding; Beigene: Consultancy, Honoraria, Research Funding; Karyopharm: Consultancy, Honoraria, Research Funding; AbbVie: Consultancy, Honoraria, Research Funding; AstraZenica: Consultancy, Honoraria; Kite, a Gilead Company: Consultancy, Honoraria, Other: Travel Support, Research Funding; Epizyme: Consultancy, Honoraria; Pfizer: Consultancy, Honoraria. Timmerman: Spectrum Pharmaceuticals: Research Funding; Bristol Myers Squibb: Research Funding; Kite, a Gilead Company: Consultancy, Research Funding; Bluebird Bio: Current equity holder in publicly-traded company; Marker Therapeutics: Current equity holder in publicly-traded company; Corvus: Current equity holder in publicly-traded company; Genmab: Current equity holder in publicly-traded company; Merck: Research Funding; TG Therapeutics: Current equity holder in publicly-traded company. Deol: Kite, a Gilead Company: Consultancy. Reagan: Seagen: Research Funding; Kite, a Gilead Company: Consultancy; Genentech: Research Funding; Curis: Consultancy. Stiff: Karyopharm: Consultancy, Honoraria; CRISPR Therapeutics: Consultancy, Honoraria; Kite, a Gilead Company: Research Funding; Amgen: Research Funding; Macrogenics: Research Funding; Bristol Myers Squibb: Research Funding; Janssen: Research Funding; Gamida Cell: Research Funding; Seagen: Research Funding; Cellectar: Research Funding; Incyte: Research Funding; BioLineRX: Research Funding; Cellectar: Research Funding; Actinium: Research Funding; MorphoSys: Consultancy, Honoraria. Flinn: Celgene: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; AstraZeneca: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Pharmacyclics LLC, an AbbVie Company: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Rhizen Pharmaceuticals: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Loxo: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Agios: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Karyopharm Therapeutics: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Forma Therapeutics: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Infinity Pharmaceuticals: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; ArQule: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Calithera Biosciences: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Yingli Pharmaceuticals: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Verastem: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Unum Therapeutics: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; AbbVie: Consultancy, Other: All Consultancy and Research Funding payments made to Sarah Cannon Research Institute, Research Funding; Kite, a Gilead Company: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Genentech: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; TG Therapeutics: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Roche: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Incyte: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Takeda: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Constellation Pharmaceuticals: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Acerta Pharma: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Novartis: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Gilead Sciences: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Merck: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Seagen: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Portola Pharmaceuticals: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; BeiGene: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Juno Therapeutics: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Janssen: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Nurix Therapeutics: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Pfizer: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Forty Seven: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Curis: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Iksuda Therapeutics: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; IGM Biosciences: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; MorphoSys: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Great Point Partners: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Teva: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Trillium Therapeutics: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Triphase Research & Development Corp.: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Century Therapeutics: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Hutchison MediPharma: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Vincerx Pharma: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Sarah Cannon Research Institute: Current Employment; Servier Pharmaceuticals: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Yingli Pharmaceuticals: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Seagen: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Servier Pharmaceuticals: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Unum Therapeutics: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute, Research Funding; Johnson & Johnson: Current holder of individual stocks in a privately-held company; Seattle Genetics: Research Funding. Farooq: Kite, a Gilead Company: Honoraria. Goy: MorphoSys: Honoraria, Other; Bristol Meyers Squibb: Membership on an entity's Board of Directors or advisory committees; OncLive Peer Exchange: Honoraria; Kite Pharma: Membership on an entity's Board of Directors or advisory committees; AstraZeneca: Membership on an entity's Board of Directors or advisory committees; Acerta: Consultancy, Research Funding; Michael J Hennessey Associates INC: Consultancy; Physicians' Education Resource: Consultancy, Other: Meeting/travel support; Vincerx: Honoraria, Membership on an entity's Board of Directors or advisory committees; Bristol Meyers Squibb: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; AbbVie/Pharmacyclics: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Incyte: Honoraria; AstraZeneca: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; AbbVie/Pharmacyclics: Membership on an entity's Board of Directors or advisory committees; Elsevier's Practice Update Oncology, Intellisphere, LLC(Targeted Oncology): Consultancy; Janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Consultancy, Honoraria; Vincerx pharma: Membership on an entity's Board of Directors or advisory committees; Medscape: Consultancy; Xcenda: Consultancy, Honoraria; Janssen: Membership on an entity's Board of Directors or advisory committees; Gilead: Membership on an entity's Board of Directors or advisory committees; Genentech/Hoffman la Roche: Research Funding; Infinity/Verastem: Research Funding; Janssen: Research Funding; Rosewell Park: Consultancy; LLC(Targeted Oncology): Consultancy; Hoffman la Roche: Consultancy; Xcenda: Consultancy; Kite, a Gilead Company: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Elsevier PracticeUpdate: Oncology: Consultancy, Honoraria; Celgene: Consultancy, Honoraria, Research Funding; Genomic Testing Cooperative: Current holder of stock options in a privately-held company, Membership on an entity's Board of Directors or advisory committees, Other: Leadership role; Karyopharm: Research Funding; Phamacyclics: Research Funding; Constellation: Research Funding; COTA (Cancer Outcome Tracking Analysis): Current holder of stock options in a privately-held company, Membership on an entity's Board of Directors or advisory committees, Other: Leadership role; Hackensack Meridian Health, Regional Cancer Care Associates/OMI: Current Employment. Muñoz: Bayer, Kite, a Gilead Company, Celgene, Merck, Portola, Incyte, Genentech, Pharmacyclics, Seagen, and Janssen, Millennium: Research Funding; Kite, a Gilead Company, Kyowa, Bayer, Pharmacyclics, Janssen, Seagen, Acrotech, Aurobindo, Beigene, Verastem, AstraZeneca, Celgene/Bristol Myers Squibb, Genentech, and Roche: Speakers Bureau; Pharmacyclics, Abbvie, Bayer, Kite, a Gilead Company, Pfizer, Janssen, Juno/Celgene, Bristol Myers Squibb, Kyowa, Alexion, Beigene, Fosun Kite, Innovent, Seagen, Debiopharm, Karyopharm, Genmab, ADC Therapeutics, Epizyme, Beigene, and Servier: Consultancy; Targeted Oncology, OncView, Kyowa, Physicians' Education Resource, and Seagen: Honoraria; OncView: Honoraria; Kyowa Kirin: Honoraria; Physicians' Education Resource: Honoraria. Siddiqi: Oncternal: Research Funding; Kite Pharma: Membership on an entity's Board of Directors or advisory committees, Research Funding; Juno Therapeutics: Membership on an entity's Board of Directors or advisory committees, Research Funding; BMS: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Pharmacyclics LLC, an AbbVie Company: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Celgene: Membership on an entity's Board of Directors or advisory committees; Janssen: Speakers Bureau; AstraZeneca: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; BeiGene: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; TG Therapeutics: Research Funding. Shen: Atara: Current Employment, Current equity holder in publicly-traded company, Other: Leadership role, Patents & Royalties; Gilead Sciences: Current equity holder in publicly-traded company; Kite, a Gilead Company: Current Employment, Other: Leadership role, Patents & Royalties. Bot: Kite, a Gilead Company: Current Employment; Gilead Sciences: Consultancy, Current equity holder in publicly-traded company, Other: Travel support. Dong: GliaCure/Tufts: Consultancy, Patents & Royalties; Gilead: Current equity holder in publicly-traded company; Kite, a Gilead Company: Current Employment. Singh: Kite, a Gilead Company: Current Employment. Spooner: Kite, a Gilead Company: Current Employment; Gilead: Current equity holder in publicly-traded company. Karalliyadda: Kite, a Gilead Company: Current Employment; Gilead: Current equity holder in publicly-traded company. Kim: Gilead Sciences: Current equity holder in publicly-traded company; Kite, a Gilead Company: Current Employment. Zheng: Gilead Sciences: Current equity holder in publicly-traded company; Kite, a Gilead Company: Current Employment. Neelapu: Kite, a Gilead Company, Merck, Bristol Myers Squibb, Novartis, Celgene, Pfizer, Allogene Therapeutics, Cell Medica/Kuur, Incyte, Precision Biosciences, Legend Biotech, Adicet Bio, Calibr, Unum Therapeutics and Bluebird Bio: Honoraria; Kite, a Gilead Company, Merck, Bristol Myers Squibb, Novartis, Celgene, Pfizer, Allogene, Kuur, Incyte, Precision BioSciences, Legend, Adicet Bio, Calibr, and Unum Therapeutics: Other: personal fees; Takeda Pharmaceuticals and related to cell therapy: Patents & Royalties; Kite, a Gilead Company, Bristol Myers Squibb, Merck, Poseida, Cellectis, Celgene, Karus Therapeutics, Unum Therapeutics (Cogent Biosciences), Allogene, Precision BioSciences, Acerta and Adicet Bio: Research Funding.

Background CD47 is an innate immune checkpoint that binds signal regulatory protein alpha (SIRPα) and delivers a "do not eat" signal to suppress macrophage phagocytosis. Overexpression of CD47 can allow tumor cells to escape immune surveillance. TTI-621 (SIRPαFc) is a fusion protein consisting of the CD47 binding domain of human SIRPα linked to the Fc region of human IgG1, designed to enhance phagocytosis and antitumor activity by blocking the CD47-SIRPα interaction between malignant cells and macrophages, and engaging Fcγ receptors. Here we report updates from the first-in-human study of TTI-621 (NCT02663518) in hematologic malignancies. Methods Study Part 1 tested increasing weekly intravenous doses of TTI-621 based on 3+3 escalation. The maximum tolerated dose was initially determined to be 0.2 mg/kg based on dose limiting toxicity (DLT) of thrombocytopenia [Grade (Gr) 4 of any duration]. Expanded testing followed in patients (pts) with hematologic malignancies, including leukemia, lymphoma, and multiple myeloma. In Part 2, most pts received 0.2 mg/kg. However, based on investigator discretion, a subset of pts received escalating doses up to 0.5 mg/kg. In Part 3, pts with T-cell lymphomas received stepwise dose escalations from 0.2 to 0.5 mg/kg over the first 5−8 weeks. In over 200 pts tested in Parts 1−3, thrombocytopenia did not increase with dose, typically recovered within 2−4 days, and was not associated with clinical sequelae. Part 4 was then undertaken to optimize TTI-621 dosing and is currently escalating doses in a 3+3 manner through pre-planned dose levels (0.5, 0.7, 1, and 1.4 mg/kg) in pts with cutaneous T-cell lymphoma (CTCL). The DLT criteria was modified to require Gr 4 thrombocytopenia lasting >72 hours. Safety monitoring includes weekly clinical laboratories and assessments of adverse events (AEs) per CTCAE v 4.03. Blood samples are obtained for pharmacokinetics (PK) and for pharmacodynamic (PD) assessments of receptor occupancy (RO) on normal peripheral T cells. Disease assessments are performed per Olsen's criteria. Results In Parts 1−3 (n=214), the most common related AEs were infusion-related reaction (IRR, 43%; 3% Gr ≥3), thrombocytopenia (30%; 22% Gr ≥3), chills (21%; 0% Gr ≥3), and fatigue (15%; 1% Gr ≥3). Objective responses to single agent TTI-621 were achieved in 14/71 (20%) NHL pts including CTCL (n=42, 1 CR, 7 PRs), PTCL (n=22, 2 CRs, 2 PRs) and DLBCL (n=7, 1 CR, 1 PR). In Part 4, as of July 10, 2020, 15 pts (9M/6F, median age 67 years) have enrolled into 4 dose cohorts (0.5−1.4 mg/kg). CTCL subtypes include mycosis fungoides (MF, n=10) and Sézary syndrome (n=5) with advanced (≥IIB) disease in 9 (60%) pts who received a median of 3 (range 1−12) prior systemic therapies. Related AEs have occurred in 11 (73%) pts including IRR (n=10) and thrombocytopenia (n=3); Gr ≥3 AEs have occurred in 4 (27%) pts including thrombocytopenia (n=3), IRRs (n=2), and exfoliative dermatitis (n=1). Thrombocytopenia generally occurred on dosing days, recovered in 2-4 days, and has not worsened with increasing doses. IRRs typically occurred during initial infusions. The Gr 3 IRR events occurred in 2 pts in the 1 and 1.4 mg/kg cohorts; low Gr IRRs have occurred across doses in 8 pts. IRRs typically resolved without recurrence and low Gr events often resolved allowing for completion of infusions. For initial infusions, the Gr 3 IRRs prompted increasing infusion times from 1 hour up to 4 hours and discretional use of steroid pre-medication. The exfoliative dermatitis occurred Day 80 and led to treatment discontinuation in 1 pt with MF whose underlying disease confounded the etiology. PK results reveal dose dependent increases in exposure; PD studies indicate ~60% RO at end of infusion up to 1 mg/kg. Antitumor activity to date includes 1 PR and 1 skin CR in 6 evaluable pts in the 1 mg/kg cohort; 2 responding pts bridged to allogeneic transplantation. The mean % change in mSWAT scores were -0.4%, -27%, and -37% for 0.5, 0.7 and 1 mg/kg cohorts, respectively. 1.4 mg/kg cohort results will be presented at the meeting. Conclusions In Parts 1−3, TTI-621 doses of 0.05 to 0.5 mg/kg were well-tolerated and demonstrated single agent activity in multiple hematologic malignancies. Preliminary data from Part 4 dose optimization indicate that weekly infusions of TTI-621 up to 1.4 mg/kg are well-tolerated without dose limiting or cumulative thrombocytopenia. Antitumor activity was seen at 1 mg/kg; dose escalation is continuing at 2 mg/kg. Disclosures Horwitz: Janssen: Consultancy; Verastem: Consultancy, Research Funding; Daiichi Sankyo: Research Funding; GlaxoSmithKline: Consultancy; ASTEX: Consultancy; Portola: Consultancy, Research Funding; C4 Therapeutics: Consultancy; Beigene: Consultancy; Myeloid Therapeutics: Consultancy; Vividion Therapeutics: Consultancy; Infinity/Verastem: Research Funding; Aileron: Consultancy, Research Funding; ADCT Therapeutics: Consultancy, Research Funding; Affirmed: Consultancy; Trillium: Consultancy, Research Funding; Corvus: Consultancy; Millenium/Takeda: Consultancy, Research Funding; Kyowa Hakka Kirin: Consultancy, Research Funding; Innate Pharma: Consultancy; Forty Seven: Consultancy, Research Funding; Seattle Genetics: Consultancy, Research Funding; Celgene: Consultancy, Research Funding; Kura Oncology: Consultancy; Miragen: Consultancy; Mundipharma: Consultancy. Foran:Agios: Honoraria, Research Funding; H3Biosciences: Research Funding; Xencor: Research Funding; Trillium: Research Funding; Takeda: Research Funding; Kura Oncology: Research Funding; Aptose: Research Funding; Aprea: Research Funding; Actinium: Research Funding; Boehringer Ingelheim: Research Funding; Abbvie: Research Funding; BMS: Membership on an entity's Board of Directors or advisory committees; Pfizer: Membership on an entity's Board of Directors or advisory committees; Servier: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees; Revolution Medicine: Consultancy. Sawas:Flatiron Health: Current Employment; Gilead: Speakers Bureau; Seattle Genetics: Speakers Bureau; Daiichi Sankyo: Speakers Bureau; Affimed: Research Funding; Roche: Current equity holder in publicly-traded company. Feldman:AstraZeneca: Consultancy; Viracta: Research Funding; Trillium: Research Funding; Pfizer: Research Funding; Janssen: Speakers Bureau; Bayer: Consultancy, Honoraria; Kyowa Kirin: Consultancy, Research Funding; Eisai: Research Funding; Cell Medica: Research Funding; Amgen: Research Funding; Pharmacyclics: Honoraria, Other, Speakers Bureau; Abbvie: Honoraria; Takeda: Honoraria, Other: Travel expenses; Celgene: Honoraria, Research Funding; Kite: Honoraria, Other: Travel expenses, Speakers Bureau; BMS: Consultancy, Honoraria, Research Funding; Corvus: Research Funding; Rhizen: Research Funding; Seattle Genetics, Inc.: Consultancy, Honoraria, Other: Travel expenses, Research Funding, Speakers Bureau; Portola: Research Funding. Sokol:EUSA Pharma: Consultancy, Honoraria, Speakers Bureau; Kyowa/Kirin Inc.: Membership on an entity's Board of Directors or advisory committees; Kymera Therapeutics: Membership on an entity's Board of Directors or advisory committees. Mei:Sanofi: Consultancy; Morphosys: Membership on an entity's Board of Directors or advisory committees. Flinn:Gilead Sciences: Consultancy, Research Funding; F. Hoffmann-La Roche: Research Funding; Roche: Consultancy, Research Funding; Vincera Pharma: Consultancy; Agios: Research Funding; Iksuda Therapeutics: Consultancy; Great Point Partners: Consultancy; Genentech, Inc.: Research Funding; Forty Seven: Research Funding; Forma Therapeutics: Research Funding; ArQule: Research Funding; Kite Pharma: Consultancy, Research Funding; Janssen: Consultancy, Research Funding; AbbVie: Consultancy, Research Funding; TG Therapeutics: Consultancy, Research Funding; Trillium Therapeutics: Research Funding; Triphase Research & Development Corp.: Research Funding; Curio Science: Consultancy; Constellation Pharmaceuticals: Research Funding; MorphoSys: Consultancy, Research Funding; Curis: Research Funding; Nurix Therapeutics: Consultancy; Novartis: Research Funding; Pfizer: Research Funding; Pharmacyclics LLC, an AbbVie Company: Consultancy, Research Funding; Portola Pharmaceuticals: Research Funding; Seattle Genetics: Consultancy, Research Funding; Teva: Research Funding; Loxo: Research Funding; BeiGene: Consultancy, Research Funding; Calithera Biosciences: Research Funding; Johnson & Johnson: Other; Rhizen Pharmaceuticals: Research Funding; Yingli Pharmaceuticals ≠: Consultancy, Research Funding; Verastem: Consultancy, Research Funding; Karyopharm Therapeutics: Research Funding; AstraZeneca: Consultancy, Research Funding; Incyte: Research Funding; Takeda: Consultancy, Research Funding; IGM Biosciences: Research Funding; Infinity Pharmaceuticals: Research Funding; Unum Therapeutics: Consultancy, Research Funding; Juno Therapeutics: Consultancy, Research Funding; Acerta Pharma: Research Funding; Celgene: Research Funding; Merck: Research Funding. Villa:Celgene: Consultancy, Honoraria; Janssen: Consultancy, Honoraria; Roche: Consultancy, Honoraria, Research Funding; AZ: Consultancy, Honoraria, Research Funding; Kite/Gilead: Consultancy, Honoraria; Nano String: Consultancy, Honoraria; Seattle Genetics: Consultancy, Honoraria; Sandoz Canada: Consultancy, Honoraria; Immunovaccine: Consultancy, Honoraria; Purdue Pharma: Consultancy, Honoraria. Percival:Pfizer: Research Funding; Trillium: Research Funding; Nohla Therapeutics: Research Funding; Biosight: Research Funding; Oscotec: Research Funding; Cardiff Oncology: Research Funding; Genentech: Membership on an entity's Board of Directors or advisory committees; Glycomimetics: Research Funding. Jagadeesh:Seattle Genetics: Membership on an entity's Board of Directors or advisory committees, Research Funding; Regeneron: Research Funding; Verastem: Membership on an entity's Board of Directors or advisory committees; MEI Pharma: Research Funding; Debiopharm Group: Research Funding. Savage:Merck, BMS, Seattle Genetics, Gilead, AstraZeneca, AbbVie, Servier: Consultancy; Roche (institutional): Research Funding; Merck, BMS, Seattle Genetics, Gilead, AstraZeneca, AbbVie: Honoraria; BeiGene: Other: Steering Committee. Akilov:Mallinckrodt: Consultancy; Medivir: Consultancy; Seattle Genetics, Inc.: Consultancy; Kyowa Hakko Kirin: Consultancy; Soligenix: Honoraria; Pfizer: Research Funding; Actelion: Consultancy, Research Funding; Trillium Therapeutics Inc.: Consultancy, Research Funding. Diefenbach:Trillium: Research Funding; Millenium/Takeda: Research Funding; Seattle Genetics: Consultancy, Research Funding; Merck: Consultancy, Research Funding; MEI: Research Funding; LAM Therapeutics: Research Funding; Incyte: Research Funding; Genentech, Inc.: Consultancy, Research Funding; Denovo: Research Funding; Bristol-Myers Squibb: Consultancy, Research Funding. Kim:Kyowa-Kirin Pharma: Research Funding; Seattle Genetics: Membership on an entity's Board of Directors or advisory committees; Medivir: Membership on an entity's Board of Directors or advisory committees; Horizon Pharma: Consultancy, Research Funding; Merck: Research Funding; miRagen: Research Funding; Trillium: Research Funding; Galderma: Membership on an entity's Board of Directors or advisory committees, Research Funding; Eisai: Membership on an entity's Board of Directors or advisory committees, Research Funding; Corvus: Research Funding; Elorac: Research Funding; Forty Seven Inc: Research Funding; Neumedicine: Consultancy, Research Funding; Innate Pharma: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Solingenix: Research Funding; Takeda: Membership on an entity's Board of Directors or advisory committees, Research Funding; Portola: Research Funding. Lin:Trillium Therapeutics Inc.: Current Employment. Catalano:Trillium Therapeutics Inc.: Current Employment. Petrova:Trillium Therapeutics Inc.: Current Employment. Uger:Trillium Therapeutics Inc.: Current Employment. Molloy:Trillium Therapeutics Inc.: Current Employment. Large:Trillium Therapeutics Inc.: Current Employment. Shou:Trillium Therapeutics Inc.: Current Employment. Ansell:Affimed: Research Funding; Bristol Myers Squibb: Research Funding; Regeneron: Research Funding; Trillium: Research Funding; ADC Therapeutics: Research Funding; Seattle Genetics: Research Funding; Takeda: Research Funding; AI Therapeutics: Research Funding.

Abstract Purpose: TTI-621 (SIRPα-IgG1 Fc) is a novel checkpoint inhibitor that activates antitumor activity by blocking the CD47 “don't eat me” signal. This first-in-human phase I study (NCT02663518) evaluated the safety and activity of TTI-621 in relapsed/refractory (R/R) hematologic malignancies. Patients and Methods: Patients with R/R lymphoma received escalating weekly intravenous TTI-621 to determine the maximum tolerated dose (MTD). During expansion, patients with various malignancies received weekly single-agent TTI-621 at the MTD; TTI-621 was combined with rituximab in patients with B-cell non-Hodgkin lymphoma (B-NHL) or with nivolumab in patients with Hodgkin lymphoma. The primary endpoint was the incidence/severity of adverse events (AEs). Secondary endpoint included overall response rate (ORR). Results: Overall, 164 patients received TTI-621: 18 in escalation and 146 in expansion (rituximab combination, n = 35 and nivolumab combination, n = 4). On the basis of transient grade 4 thrombocytopenia, the MTD was determined as 0.2 mg/kg; 0.1 mg/kg was evaluated in combination cohorts. AEs included infusion-related reactions, thrombocytopenia, chills, and fatigue. Thrombocytopenia (20%, grade ≥3) was reversible between doses and not associated with bleeding. Transient thrombocytopenia that determined the initial MTD may not have been dose limiting. The ORR for all patients was 13%. The ORR was 29% (2/7) for diffuse large B-cell lymphoma (DLBCL) and 25% (8/32) for T-cell NHL (T-NHL) with TTI-621 monotherapy and was 21% (5/24) for DLBCL with TTI-621 plus rituximab. Further dose optimization is ongoing. Conclusions: TTI-621 was well-tolerated and demonstrated activity as monotherapy in patients with R/R B-NHL and T-NHL and combined with rituximab in patients with R/R B-NHL.

Background: Axi-cel is an autologous anti-CD19 chimeric antigen receptor (CAR) T cell therapy approved for the treatment of patients (pts) with relapsed/refractory large B cell lymphoma (LBCL) with ≥ 2 prior systemic therapies. ZUMA-1 is the multicenter, single-arm, registrational Phase 1/2 study of axi-cel in pts with refractory LBCL. In a 2-year analysis of ZUMA-1 (median follow-up, 27.1 months; N=101), axi-cel demonstrated objective response, complete response (CR), and ongoing response rates of 83%, 58%, and 39%, respectively (Locke et al. Lancet Oncol. 2019). Here, we present additional survival follow up and recovery of normal, polyclonal B cells from ongoing responders in ZUMA-1. Methods: Eligible pts with refractory large B cell lymphoma (diffuse large B cell lymphoma, primary mediastinal B cell lymphoma, transformed follicular lymphoma) underwent leukapheresis at enrollment and subsequently received low-dose conditioning chemotherapy (fludarabine and cyclophosphamide) followed by a target dose of 2 × 106 anti-CD19 CAR T cells/kg (Neelapu et al. NEJM. 2017; NCT02348216). The primary endpoint was objective response rate (ORR), and the first response assessment was 4 weeks post infusion. Response assessments were performed per protocol up to 24 months or disease progression, whichever occurred first. For pts in ongoing response beyond Month 24, response assessments continued per institutional standard-of-care (SOC). Blood levels of CAR T cells were quantified using polymerase chain reaction and B cells were characterized using flow cytometry in pts with ongoing responses and evaluable samples. Results: A total of 111 pts were enrolled, and axi-cel was administered to 101 pts. As previously reported in the ZUMA-1 2-year analysis, among pts who received axi-cel, the median time from axi-cel infusion to both objective response and CR was 1.0 month (range, 1 - 12 months; Locke et al. Lancet Oncol 2019). When the entire enrolled population (N = 111) was included on an intent-to-treat basis, the median manufacturing time was 17 days (range, 14 - 51; n = 110 as manufacturing was not feasible for 1 pt). Additionally, among the 111 pts, the median time from enrollment/leukapheresis to objective response and CR was 1.7 months (range, 0.7 - 12.9) and 1.9 months (range, 0.7 - 13.3), respectively. Responses have been durable, and with a minimum of 3 years of follow-up (median, 39.1 months), the median overall survival (OS) was 25.8 months, and the 3-year OS rate was 47%. Importantly, no axi-cel-related secondary malignancies have been reported. As previously reported, pts in ongoing response after 2 years had significantly greater peak CAR T cell expansion in blood 7 - 14 days after axi-cel infusion than did those with relapse (P = 0.014) or no response (P = 0.0003; Locke et al. Lancet Oncol 2019). Blood samples from 22 pts in ongoing response (per institutional SOC) at ≥ 3 years were available for analysis of CAR T cells and evaluation of B cell recovery. All evaluable pts had detectable B cells in blood at 3 years post axi-cel. Notably, 91% of pts in ongoing response at 3-year follow-up demonstrated recovery of polyclonal B cells measured by presence of both kappa and lambda light chains on non-malignant CD19+CD20+ B cells. The median kappa-lambda ratio of 1.6 and relative levels of key B cell subsets, including memory and naive B cell immunophenotypes, suggested reconstitution of B cell repertoire, consistent with published data from healthy individuals (Deneys et al. J Immunol Methods 2001; Scott et al. J Clin Pathol 2018). Additionally, 15/22 (68%) had both minimal levels of detectable CAR gene-marked cells and detectable polyclonal B cells in blood. Altogether, these findings support the hypothesis that persistence of functional CAR T cells is not necessary for durable remissions of LBCL. Overall survival and translational findings with ≥ 4 years of follow-up will be presented. Conclusions: Axi-cel produced rapid responses and longterm disease control in pts with refractory LBCL. Most responses occurred by the first assessment, and the brief time elapsed between enrollment and response supports both the speed and success of manufacturing. Furthermore, axi-cel-treated pts with ongoing responses at ≥ 3 years showed evidence of restoration of a normal B cell compartment and clearance of functional CAR T cells, a critical component of the long-term safety of CD19-directed CAR T cell therapies. Disclosures Locke: Kite, a Gilead Company: Consultancy, Research Funding; Wugen: Consultancy; Calibr: Consultancy; Allogene: Consultancy; Cellular Biomedicine Group: Other: Consultancy with grant options; GammaDelta Therapeutics: Consultancy; Celgene/Bristol-Myers Squibb: Consultancy; Novartis: Consultancy. Ghobadi:Celegene: Consultancy; Wugen: Consultancy; Atara: Consultancy; Kite, a Gilead Company: Consultancy, Research Funding, Speakers Bureau; EUSA: Consultancy. Miklos:Novartis: Consultancy, Other: Travel support, Research Funding; Allogene Therapeutics Inc.: Research Funding; Juno-Celgene-Bristol-Myers Squibb: Consultancy, Other: Travel support, Research Funding; Janssen: Consultancy, Other: Travel support; Miltenyi Biotec: Research Funding; Pharmacyclics: Consultancy, Other: Travel support, Patents & Royalties, Research Funding; Adaptive Biotech: Consultancy, Other: Travel support, Research Funding; Kite-Gilead: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: Travel support, Research Funding. Oluwole:Pfizer: Consultancy; Kite, a Gilead Company: Consultancy, Honoraria, Research Funding; Spectrum Pharmaceuticals: Consultancy; Bayer: Consultancy. Lin:Legend BioTech: Consultancy; Juno: Consultancy; Bluebird Bio: Consultancy, Research Funding; Celgene: Consultancy, Research Funding; Novartis: Consultancy; Janssen: Consultancy, Research Funding; Kite, a Gilead Company: Consultancy, Research Funding; Gamida Cells: Consultancy; Sorrento: Consultancy, Membership on an entity's Board of Directors or advisory committees; Takeda: Research Funding; Merck: Research Funding; Vineti: Consultancy. Hill:Kite, a Gilead Company: Consultancy, Honoraria, Research Funding; AstraZenica: Consultancy, Honoraria, Research Funding; Beigene: Consultancy, Honoraria, Research Funding; Novartis: Consultancy, Honoraria; BMS: Consultancy, Honoraria, Research Funding; Celgene: Consultancy, Honoraria, Research Funding; Takeda: Research Funding; Karyopharm: Consultancy, Honoraria, Research Funding; Pharmacyclics: Consultancy, Honoraria, Research Funding; Abbvie: Consultancy, Honoraria, Research Funding; Genentech: Consultancy, Honoraria, Research Funding. Timmerman:Merck: Research Funding; Corvus: Current equity holder in publicly-traded company; Marker Therapeutics: Current equity holder in publicly-traded company; Immune Design: Honoraria; Celldex Therapeutics: Consultancy; BMS: Other: Travel support, Research Funding; Spectrum Pharmaceuticals: Research Funding; Kite, a Gilead Company: Consultancy, Other: Travel support, Research Funding; Bluebird Bio: Current equity holder in publicly-traded company; Genmab: Current equity holder in publicly-traded company; Valor: Research Funding. Deol:Novartis: Consultancy; Kite, a Gilead Company: Consultancy. Reagan:Kite, a Gilead Company: Consultancy; Curis: Consultancy; Seattle Genetics: Research Funding. Stiff:Kite, a Gilead Company: Research Funding; Delta-Fly: Research Funding; Gamida Cell: Research Funding; Atara: Research Funding; Unum: Research Funding; Macrogenics: Research Funding; Amgen: Research Funding. Flinn:Celgene: Research Funding; TG Therapeutics: Consultancy, Research Funding; Trillium Therapeutics: Research Funding; Curio Science: Consultancy; Merck: Research Funding; Constellation Pharmaceuticals: Research Funding; BeiGene: Consultancy, Research Funding; ArQule: Research Funding; Kite Pharma: Consultancy, Research Funding; Genentech, Inc.: Research Funding; Pfizer: Research Funding; Calithera Biosciences: Research Funding; Agios: Research Funding; Karyopharm Therapeutics: Research Funding; AstraZeneca: Consultancy, Research Funding; Forty Seven: Research Funding; Forma Therapeutics: Research Funding; Loxo: Research Funding; F. Hoffmann-La Roche: Research Funding; Incyte: Research Funding; Pharmacyclics LLC, an AbbVie Company: Consultancy, Research Funding; Novartis: Research Funding; MorphoSys: Consultancy, Research Funding; Rhizen Pharmaceuticals: Research Funding; Yingli Pharmaceuticals ≠: Consultancy, Research Funding; Johnson & Johnson: Other; Roche: Consultancy, Research Funding; Vincera Pharma: Consultancy; Gilead Sciences: Consultancy, Research Funding; AbbVie: Consultancy, Research Funding; Janssen: Consultancy, Research Funding; Iksuda Therapeutics: Consultancy; Great Point Partners: Consultancy; Curis: Research Funding; Nurix Therapeutics: Consultancy; Portola Pharmaceuticals: Research Funding; Acerta Pharma: Research Funding; Juno Therapeutics: Consultancy, Research Funding; Unum Therapeutics: Consultancy, Research Funding; Infinity Pharmaceuticals: Research Funding; IGM Biosciences: Research Funding; Takeda: Consultancy, Research Funding; Teva: Research Funding; Seattle Genetics: Consultancy, Research Funding; Triphase Research & Development Corp.: Research Funding; Verastem: Consultancy, Research Funding. Farooq:Kite, a Gilead Company: Honoraria. Goy:COTA: Consultancy, Current equity holder in publicly-traded company, Other: leadership role; Karyopharm: Research Funding; Genentech/Roche: Research Funding; Constellation: Research Funding; Bayer: Research Funding; CALBG: Research Funding; PracticeUpdate Oncology: Consultancy; RCCA/OMI: Current Employment; Acerta: Consultancy, Honoraria, Other: leadership role, Research Funding; AstraZeneca: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: leadership role, Research Funding; Celgene: Honoraria, Research Funding; Hackensack UMC and University of Nebraska: Research Funding; Infinity: Research Funding; Xcenda: Consultancy; Infinity Verastem: Research Funding; Morphosys: Research Funding; AbbVie: Research Funding; MD Anderson: Research Funding; Regional Cancer Care Associates/OMI: Current Employment; Kite, a Gilead Company: Consultancy, Current equity holder in publicly-traded company, Honoraria, Other: leadership role, Research Funding; Janssen: Consultancy, Honoraria, Other: leadership role, Research Funding. McSweeney:Kite, a Gilead Company: Consultancy, Honoraria, Research Funding, Speakers Bureau; Colorado Blood Cancer Institute: Current Employment; Fred Hutchinson: Patents & Royalties. Munoz:Juno/Celgene/BMS: Consultancy, Research Funding, Speakers Bureau; Alexion: Consultancy; Beigene: Consultancy, Speakers Bureau; Fosunkite: Consultancy; Innovent: Consultancy; Acrotech/Aurobindo: Speakers Bureau; Kyowa: Consultancy, Honoraria, Speakers Bureau; Janssen: Consultancy, Research Funding, Speakers Bureau; Pfizer: Consultancy; Verastem: Speakers Bureau; AstraZeneca: Speakers Bureau; Genentech/Roche: Research Funding, Speakers Bureau; AbbVie: Consultancy, Speakers Bureau; Merck: Research Funding; Portola: Research Funding; Incyte: Research Funding; Millenium: Research Funding; Kite, a Gilead Company: Consultancy, Research Funding, Speakers Bureau; Pharmacyclics: Consultancy, Research Funding, Speakers Bureau; Bayer: Consultancy, Research Funding, Speakers Bureau; Seattle Genetics: Consultancy, Honoraria, Research Funding, Speakers Bureau. Siddiqi:Oncternal: Research Funding; TG Therapeutics: Research Funding; Janssen: Speakers Bureau; Seattle Genetics: Speakers Bureau; AstraZeneca: Consultancy, Research Funding, Speakers Bureau; BeiGene: Consultancy, Research Funding; Pharmacyclics: Consultancy, Research Funding, Speakers Bureau; Celgene: Consultancy, Research Funding; Juno: Consultancy, Research Funding; Kite, a Gilead Company: Consultancy, Research Funding. Rossi:Gilead Sciences: Current equity holder in publicly-traded company; Kite, a Gilead Company: Current Employment. Bot:Kite, a Gilead Company: Current Employment; Gilead Sciences: Consultancy, Current equity holder in publicly-traded company, Other: Travel support . Zheng:Kite, a Gilead Company: Current Employment; Gilead Sciences: Current equity holder in publicly-traded company. Vezan:Merck: Current equity holder in publicly-traded company; Abbvie: Current equity holder in publicly-traded company; Kite, a Gilead Company: Current Employment, Honoraria, Other: Travel support. Bashir:Kite, a Gilead Company: Current Employment; OmniacPharmConsult Ltd: Current Employment, Current equity holder in private company. Kim:Kite, a Gilead Company: Current Employment; Gilead Sciences: Current equity holder in publicly-traded company. Chu:Kite, a Gilead Company: Current Employment; Gilead Sciences: Current equity holder in publicly-traded company; Amgen: Current equity holder in publicly-traded company; Celgene: Current equity holder in publicly-traded company. Neelapu:N/A: Other; Takeda Pharmaceuticals: Patents & Royalties; Acerta: Research Funding; Karus Therapeutics: Research Funding; Cellectis: Research Funding; Poseida: Research Funding; Unum Therapeutics: Other, Research Funding; Calibr: Other; Kite, a Gilead Company: Other: personal fees, Research Funding; Bristol-Myers Squibb: Other: personal fees, Research Funding; Merck: Other: personal fees, Research Funding; Novartis: Other: personal fees; Celgene: Other: personal fees, Research Funding; Pfizer: Other: personal fees; Allogene Therapeutics: Other: personal fees, Research Funding; Adicet Bio: Other; Legend Biotech: Other; Precision Biosciences: Other: personal fees, Research Funding; Incyte: Other: personal fees; Cell Medica/Kuur: Other: personal fees.

Abstract CD27, a costimulatory molecule on T cells, induces intracellular signals mediating cellular activation, proliferation, effector function, and cell survival on binding to its ligand, CD70. Varlilumab, a novel, first-in-class, agonist immunoglobulin G1 anti-CD27 antibody, mediates antitumor immunity and direct killing of CD27+ tumor cells in animal models. This first-in-human, dose-escalation, and expansion study evaluated varlilumab in patients with hematologic malignancies. Primary objectives were to assess safety and the maximum tolerated and optimal biologic doses of varlilumab. Secondary objectives were to evaluate pharmacokinetics, pharmacodynamics, immunogenicity, and antitumor activity. In a 3 + 3 dose-escalation design, 30 patients with B-cell (n = 25) or T-cell (n = 5) malignancies received varlilumab (0.1, 0.3, 1, 3, or 10 mg/kg IV) as a single dose with a 28-day observation period, followed by weekly dosing (4 doses per cycle, up to 5 cycles, depending on tumor response). In an expansion cohort, 4 additional patients with Hodgkin lymphoma received varlilumab at 0.3 mg/kg every 3 weeks (4 doses per cycle, up to 5 cycles). No dose-limiting toxicities were observed. Treatment-related adverse events, generally grade 1 to 2, included fatigue, decreased appetite, anemia, diarrhea, and headache. Exposure was linear and dose-proportional across dose groups and resulted in increases in proinflammatory cytokines and soluble CD27. One patient with stage IV Hodgkin lymphoma experienced a complete response and remained in remission at >33 months with no further anticancer therapy. These data support further investigation of varlilumab for hematologic malignancies, particularly in combination approaches targeting nonredundant immune regulating pathways. This trial was registered at www.clinicaltrials.gov as #NCT01460134.

Abstract We previously demonstrated that apoptosis-inhibiting proteins (e.g., Bcl-2, Mcl-1, and XIAP) are important in predicting response to chemotherapy and antibody therapy for CLL. Additionally, genetic abnormalities and epigenetic control of gene expression have become increasingly important in understanding the prognosis and potential therapeutic opportunities in this disease. Greater than 80% of patients with CLL have genetic abnormalities detectable by FISH. Important subsets include those with a less favorable prognosis (deletions of 17p, 11q), an intermediate prognosis (trisomy 12), or a favorable outcome (deletion of 13q). PTPRO, encoding a receptor-type tyrosine phosphatase, is a specific tumor suppressor gene located in chromosomal region 12p12.3. PTPRO has been highly characterized as inhibiting anchorage-independent tumor growth in human lung carcinomas. This gene has been found to be silenced by promoter methylation, and can be re-expressed by hypomethylating agents in human lung tumor models. Thus, we examined the methylation profile of the promoter region of PTPRO in primary leukemic cells from patients with CLL, and in B cells obtained from normal volunteers. Analysis of the PTPRO CpG island by methylation-specific PCR and combined bisulfite restriction analysis (COBRA) demonstrated that this region was methylated in 91% of samples from 46 patients, whereas it was unmethylated in control B cells from normal volunteers. Specific quantitative determinations of important proteins related to apoptosis in the leukemic cells from 20 of these patients showed that, in the group with methylation of the PTPRO promoter, there was a significant elevation of Bcl-2 (p=0.079), Mcl-1 (p=0.004), XIAP (p=0.048), Bcl-2/BAX ratio (p=0.0024), and Mcl-1/BAX ratio (p=0.0017). There was no apparent relationship with FISH category or immunoglobulin VH mutational status. Thus, PTPRO promoter methylation analysis may identify a subset of CLL patients less likely to respond to therapy, and provide a potential reversible target for new therapeutic approaches to this disease. Finally, analysis of methylation of CLL samples by restriction landmark genome scanning also revealed methylation of genes for three additional protein tyrosine phosphatases: PTPRN2, PTPRZ2, and PTPN11. Increases in methylation of two of these (PTPRN2 and PTPRZ2) in CLL samples relative to control B cells was confirmed by COBRA. These results provide additional potential molecular targets for CLL therapy.

Abstract We performed immunophenotypic and IgVH mutation analyses on the chronic lymphocytic leukemia (CLL) cells of 307 patients for expression of CD38, ZAP-70, and IgVH mutation status to determine the relative strength of each in predicting the need for early treatment. For this we assessed the time from diagnosis to initial therapy for progressive and/or symptomatic disease. Patients confirmed to have remained untreated were censored for this endpoint. Expression of CD38 was defined as the proportion of CD38-stained CLL cells that had fluorescence intensity above a defined threshold. Similarly, cases were defined as ZAP-70+ when 20% or more of the ZAP-70-stained CLL cells had fluorescence intensity above a defined threshold, as described (NEJM351:893, 2004). CLL cells were classified as expressing mutated IgVH genes if they expressed IgVH with <98% homology with a known germline IgVH gene. The median percentage of cells expressing CD38 in our cohort was 11.5% (range 0.1% to 99.5%). In patients with multiple samples, the CD38 expression level appeared constant over time, with a median S.D. of 0.8%. We defined patient samples that had CD38 expression levels at or below the median as having low expression. There was a significant association between low expression of CD38 and lack of ZAP-70 or expression of a mutated IgVH (p < 0.0001 for each assessment by the Fisher exact test). Median level of CD38 among cases expressing mutated IgVH was 4.0%, compared to 27.4% among cases expressing unmutated IgVH (p < 0.0001 by the Wilcoxon rank sum test). Median level of CD38 among ZAP-70 negative cases was 5.3%, compared to 27.2% among ZAP-70+ cases (p < 0.0001 by the Wilcoxon rank sum test). Patients with low-level expression of CD38 had a median time to initiation of therapy of 8.2 years; whereas, patients with high-level expression of CD38 had a median time to initiation of therapy of 4.0 years (p<0.0001). Although high-level expression of CD38 was associated with a shorter time from diagnosis to initiation of therapy (p < 0.0001 in a Cox proportional hazards regression), the inclusion of IgVH mutation status (p < 0.0001) or expression of ZAP-70 (p < 0.0001) in these models reduced the contribution of CD38 status to a p-value of 0.051 (ZAP-70 model) or 0.052 (mutation status model). Although ZAP-70 expression and mutation status each contributed significantly to the hazard of initiating therapy in a Cox proportional hazards model, high-level expression of CD38 did not add significantly to the model that already addresses ZAP-70 and mutational status, p=0.425. As such, although knowledge of the CD38 expression level can be used as a predictor of the time from diagnosis to the initiation of therapy it provides only marginal value if either the IgVH mutational status or expression of ZAP-70 is known and no value if knowledge of both ZAP-70 expression and IgVH mutational status is available.