Savage, Kerry J.

Abstract Introduction: Nivolumab (nivo), an immune checkpoint inhibitor targeting the programmed death-1 (PD-1) receptor, augments T-cell activation and restores antitumor T-cell function. In the phase 2 CheckMate 205 study (NCT02181738), nivo demonstrated frequent (65-73%) and durable objective responses across 3 cohorts of patients (pts) with relapsed/refractory (R/R) cHL after failure of autologous hematopoietic cell transplantation (Fanale M et al. ICML 2017 [oral 125]). While most pts with cHL are cured with first-line therapy, those with advanced-stage disease are more likely to relapse or progress. More aggressive regimens (eg, BEACOPPesc., Borchmann P et al. Lancet Oncol 2017) are associated with improved progression-free survival (PFS) but are hampered by excessive toxicities and have limited applicability in elderly pts.PD-1 ligand gene amplification has been linked to poorer outcomes in cHL pts treated with standard induction regimens (Roemer MG et al. J Clin Oncol 2016) but is associated with improved responses to nivo in R/R cHL (Younes A et al. Lancet Oncol 2016), suggesting that PD-1 blockade may benefit pts in the frontline setting. We therefore assessed the safety and efficacy of nivo as a single-agent lead-in treatment followed by nivo in combination with chemotherapy, excluding bleomycin due to potential overlapping pulmonary toxicity, for pts with previously untreated advanced-stage cHL. Methods: Cohort D of CheckMate 205 enrolled untreated pts (aged ≥18 y) with advanced-stage newly diagnosed cHL (stage III, IV, or II with B symptoms and extranodal or bulky disease) and ECOG score 0-1. Pts received 4 biweekly doses of nivo monotherapy (240 mg IV flat dose) followed by nivo plus chemotherapy (nivo 240 mg IV, doxorubicin, vinblastine, dacarbazine [N-AVD]) for 6 cycles (12 doses). The primary endpoint was safety and tolerability: proportion of pts with ≥1 grade (G) 3-5 treatment-related adverse event (TRAE) ≤30 d after last dose. Additional endpoints included rates of discontinuation and of independent radiologic review committee-assessed complete remission (CR). Results: At database lock (June 2017), 51 pts had been treated, with a median (range) follow-up of 8 (1-11) mo. Median (range) age was 37 (18-87) y; 29 (57%) pts had stage IV disease, and 41 (80%) had B symptoms. At baseline, 7 (14%) pts had bulky disease and 17 (33%) had extranodal involvement. International prognostic score was ≥3 in 25 (49%) pts. At analysis, 49 (96%) pts had completed nivo monotherapy treatment, receiving all 4 doses; 1 pt discontinued due to disease progression and 1 due to study drug toxicity (G1-2 hyperthyroidism), subsequently receiving AVD only. TRAEs for both treatment phases are shown in the Table. During nivo monotherapy, 2 pts had 1 dose delay each due to an AE; 2 (4%) pts had serious AEs (SAEs; 1 G1-2 hyperthyroidism; 1 G1-2 polyneuropathy); an immune-mediated AE (IMAE), G1-2 hyperthyroidism, was reported in 2 (4%) pts. Fifty pts started combination therapy; at database lock, 35 (70%) had completed therapy, with 34 (69%) receiving 12 N-AVD doses. With N-AVD, 10 (20%) pts had SAEs, 6 G3-4; the most common G3-4 SAE was febrile neutropenia in 2 (4%) pts; IMAEs occurring in >1 pt were hypothyroidism in 8 (16%) pts and increased ALT in 2 (4%). AEs leading to discontinuation of N-AVD occurred in 2 pts: G1-2 hepatic abnormality, and G3-4 febrile neutropenia (FN) and Klebsiella bacteremia. The pt who developed FN and Klebsiella bacteremia died 38 d after the first dose of his fifth cycle of N-AVD due to study drug toxicity of acute respiratory insufficiency. Important primary, secondary, and exploratory endpoints (including CR and objective response rates at end of monotherapy, after 2 combocycles and end of therapy, and PFS) will be presented at the meeting. Conclusions: Nivo monotherapy followed by N-AVD combination therapy was well-tolerated in pts with newly diagnosed, untreated, advanced-stage cHL. Nearly all pts completed nivo monotherapy treatment and started combination therapy with N-AVD. The safety profile was consistent with historical experience of nivo and AVD separately, with no new safety signals. Nivo followed by N-AVD may provide a tolerable alternative treatment option to standard-of-care multi-agent chemotherapy for pts with newly diagnosed advanced-stage cHL. Study support: BMS. Writing support: Matthew Thomas, PhD, Caudex, funded by BMS. Disclosures Ramchandren: Janssen: Research Funding; Pharmacyclics: Research Funding; Merck: Research Funding; Seattle Genetics: Consultancy. Fanale: CELGENE: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; BMS: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; ADC THERAPEUTICS: Research Funding; GENENTECH: Research Funding; MERCK: Membership on an entity's Board of Directors or advisory committees, Research Funding; MOLECULAR TEMPLATES: Research Funding; AMGEN: Membership on an entity's Board of Directors or advisory committees; SEATTLE GENETICS: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; TAKEDA: Honoraria, Research Funding; ONYX: Research Funding. Rueda: Bristol-Myers Squibb: Consultancy. Armand: Roche: Research Funding; Genmab: Consultancy; Infinity: Consultancy; Sigma Tau: Research Funding; Tensha: Research Funding; Affimed: Research Funding; Bristol-Myers Squibb: Consultancy, Research Funding; Otsuka: Research Funding; Pfizer: Consultancy, Research Funding; Merck & Co., Inc.: Consultancy, Research Funding; Sequenta/Adaptive: Research Funding. Trněný: Janssen: Consultancy, Honoraria; Roche: Consultancy, Honoraria, Research Funding; Celgene: Consultancy, Honoraria, Research Funding; Abbvie: Consultancy, Honoraria; BMS: Consultancy, Honoraria; Takeda: Consultancy, Honoraria; Gilead: Consultancy, Honoraria. Feldman: Pharmacyclics: Speakers Bureau; Celgene: Speakers Bureau; Bristol-Myers Squibb: Consultancy; Kite Pharma: Speakers Bureau; Seattle Genetics: Honoraria, Research Funding, Speakers Bureau; AbbVie: Speakers Bureau; Janssen: Speakers Bureau. Ansell: Merck: Research Funding; Seattle Genetics: Research Funding; Bristol-Myers Squibb: Research Funding; Celldex: Research Funding; Affimed: Research Funding. Jaeger: Janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel, Accommodations, Expenses; Novartis Pharmaceuticals Corporation: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees; Roche: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel, Accommodations, Expenses. Cohen: Bioinvent: Consultancy, Membership on an entity's Board of Directors or advisory committees; LAM Therapeutics, Inc: Research Funding; Abbvie: Consultancy, Membership on an entity's Board of Directors or advisory committees; Janssen: Consultancy, Membership on an entity's Board of Directors or advisory committees; Genentech: Consultancy, Membership on an entity's Board of Directors or advisory committees; Takada: Research Funding; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Bristol Myers Squibb: Research Funding; Infinity: Consultancy, Membership on an entity's Board of Directors or advisory committees. Savage: Bristol-Myers Squibb: Honoraria; Seattle Genetics: Consultancy, Honoraria; Roche: Research Funding; Celgene: Consultancy; Merck: Honoraria. Willenbacher: Bristol-Myers Squibb: Consultancy, Honoraria. Sacchi: Bristol-Myers Squibb: Employment. Sumbul: Bristol-Myers Squibb: Employment.

Introduction Historically, nearly all relapses in classical Hodgkin lymphoma (cHL) occur within the first 5 years (Radford et al, BMJ 1997). In the phase 3 ECHELON-1 study (NCT01712490), treatment with brentuximab vedotin, doxorubicin, vinblastine, and dacarbazine (A+AVD) significantly improved modified progression-free survival (PFS) in patients (pts) with newly-diagnosed Stage III/IV cHL compared with doxorubicin, bleomycin, vinblastine, and dacarbazine (ABVD) (Connors et al, NEJM 2018). 3- and 4-year follow-up (Straus et al, Blood 2020; Bartlett et al, Blood 2019) reported durable PFS benefit with A+AVD vs ABVD in the intent-to-treat (ITT) population that was consistent across most key pt subgroups, irrespective of interim positron emission tomography (PET) scan status, disease stage, and baseline disease risk factor score. We report updated efficacy and safety results for pts in the ECHELON-1 study after a median follow-up of 55.6 months. Methods In this evaluation of longer follow-up, an exploratory analysis of PFS (time from randomization to relapse, progression, or death from any cause) per investigator (INV) was conducted, with a cutoff date of May 18, 2020. Pts with previously untreated Stage III or IV cHL were randomized 1:1 to receive up to six cycles of A+AVD (n=664) or ABVD (n=670) intravenously on days 1 and 15 of a 28-day cycle. An interim PET scan after cycle 2 (PET2) was required. Resolution and improvement (defined as improvement by ≥1 grade from worst grade as of the latest assessment) of peripheral neuropathy (PN) in pts with ongoing symptoms at the end of treatment (EoT) were monitored during the extended follow-up period. The rate of secondary malignancies, and the incidence and outcomes of pregnancies among pts and their partners were also assessed. Results With extended follow-up (median 55.6 months; 95% CI 55.2-56.7) estimated 5-year PFS rates were 82.0% (95% CI 78.7-84.8) for A+AVD and 75.2% (95% CI 71.5-78.4) for ABVD. Overall, PFS per INV favored A+AVD over ABVD (HR 0.691; 95% CI 0.543-0.880; p=0.003) (Table). Exploratory subgroup analyses by PET2 status and age demonstrated PFS benefits regardless of PET2 status (Table); estimated 5-year PFS per INV with A+AVD vs ABVD in the ITT population was 84.7% vs 78.8% in PET2-negative pts (HR 0.676; 95% CI 0.512-0.892; p=0.005), and 60.6% vs 45.9% in PET2-positive pts (HR 0.703; 95% CI 0.393-1.256; p=0.230). PFS benefit with A+AVD over ABVD was also independent of the number of International Prognostic Factors Project (IPFP) risk factors (Figure). After a median follow-up of almost 5-years, 84% (370/442) and 86% (245/286) of pts with treatment-emergent PN reported complete resolution or improvement of symptoms in the A+AVD and ABVD arms, respectively. Median time to complete resolution of PN events that were ongoing at EoT was 30 weeks (range 0-262) in the A+AVD arm and 16 weeks (range 0-267) in the ABVD arm; median time to improvement was 49 weeks (range 8-270) and 12 weeks (range 2-70) , respectively. Of the 132 (30%) pts with ongoing PN in the A+AVD arm, 77 (17%), 39 (9%), 15 (3%) and 1 (<1%) experienced a maximum severity of grade 1, 2, 3 or 4, respectively. In the ABVD arm, PN was ongoing in 61 pts (21%); maximum severity was grade 1, 2, 3 or 4 in 40 (14%), 17 (6%), 4 (1%) and 0 pts, respectively. A total of 124 pregnancies were reported among pts and their partners (40 female and 30 male pts in the A+AVD arm; 26 female and 28 male pts in the ABVD arm). The proportion of live births was similar between arms for female pts (26/40 in the A+AVD arm and 17/26 in the ABVD arm, 65% in each arm) and for male pts' partners (19/30 [63%] in the A+AVD arm and 20/28 [71%] in the ABVD arm). No stillbirths were recorded. Additional follow-up at an estimated median of ~5 years and secondary malignancy data will be presented. Conclusions After a median follow-up of 55.6 months, A+AVD continues to demonstrate a robust and durable treatment benefit independent of disease stage, risk factor score, and PET2 status. In addition, compared with ABVD, treatment adaptation by interim PET2 status is not required and bleomycin exposure is avoided. The sustained PFS benefit with A+AVD is coupled with a manageable safety profile with symptoms of PN improving or resolving over time and similar pregnancy rates in both treatment arms. The benefits observed with A+AVD at this important milestone suggest that A+AVD is an attractive treatment option for all pts with previously untreated Stage III or IV cHL. Disclosures Straus: Karyopharm Therapeutics: Membership on an entity's Board of Directors or advisory committees; Imedex, Inc.: Speakers Bureau; Targeted Oncology: Consultancy, Speakers Bureau; NY Lymphoma Rounds: Consultancy; Takeda Pharmaceuticals: Research Funding, Speakers Bureau; OncLive: Speakers Bureau; Elsevier: Membership on an entity's Board of Directors or advisory committees, Other: CME writer; ASH: Other: Conference in December 2019 on HL to other physicians during ASH; Seattle Genetics: Consultancy, Membership on an entity's Board of Directors or advisory committees. Connors:Seattle Genetics: Other: Sponsorship to educational presentations; Takeda: Other: Sponsorship to educational presentations. Illés:Takeda, Seattle Genetics: Research Funding; Novartis, Janssen, Pfizer, Roche;: Other: Travel, Accommodations, Expenses; Janssen, Celgene, Takeda, Novartis Pharma SAS, Pfizer Pharmaceuticals Israel, Roche;: Consultancy, Honoraria; Celgene, Janssen, Novartis,Roche, Takeda: Consultancy. Lech-Marańda:Roche, Novartis, Takeda, Janssen-Cilag, Amgen, Gilead, AbbVie, Sanofi: Consultancy; Roche, Amgen, Gilead: Speakers Bureau. Feldman:KITE: Honoraria, Speakers Bureau; Abbvie: Honoraria, Speakers Bureau; Morphosis: Other: Ad board; AstraZeneca: Other: Ad board; BMS/Celgene: Consultancy, Honoraria, Speakers Bureau; Seattle Genetics: Consultancy, Speakers Bureau; Janssen: Honoraria, Speakers Bureau; Pharmacyclics: Honoraria, Speakers Bureau; Takeda: Honoraria, Speakers Bureau. Smolewski:Roche Poland: Consultancy, Honoraria; Takeda: Consultancy, Honoraria; Sandoz: Honoraria; Morphosis: Honoraria. Savage:Roche (institutional): Research Funding; Merck, BMS, Seattle Genetics, Gilead, AstraZeneca, AbbVie, Servier: Consultancy; BeiGene: Other: Steering Committee; Merck, BMS, Seattle Genetics, Gilead, AstraZeneca, AbbVie: Honoraria. Bartlett:Pfizer: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Pharmacyclics: Research Funding; Seattle Genetics: Consultancy, Research Funding; Roche/Genentech: Consultancy, Research Funding; Seattle Genetics: Membership on an entity's Board of Directors or advisory committees, Research Funding; BTG: Consultancy; Acerta: Consultancy; Affimed Therapeutics: Research Funding; ADC Therapeutics: Consultancy; Autolus: Research Funding; BMS/Celgene: Research Funding; Forty Seven: Research Funding; Immune Design: Research Funding; Janssen: Research Funding; Kite, a Gilead Company: Research Funding; Merck: Research Funding; Millennium: Research Funding. Walewski:Gilead: Consultancy, Honoraria; Servier: Consultancy, Honoraria; BMS: Consultancy, Honoraria; Celgene: Consultancy, Honoraria; Amgen: Consultancy, Honoraria; Abbvie: Consultancy, Honoraria; Takeda: Consultancy, Honoraria, Research Funding; Roche: Consultancy, Honoraria, Other: Travel Support, Research Funding; Novartis: Consultancy, Honoraria, Research Funding; Janssen: Consultancy, Honoraria, Research Funding; GSK: Research Funding. Ramchandren:Janssen: Research Funding; Pharmacyclics LLC, an AbbVie Company: Consultancy, Research Funding. Zinzani:Eusapharma: Consultancy, Speakers Bureau; Gilead: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Portola: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Immune Design: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Kyowa Kirin: Consultancy, Speakers Bureau; MSD: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Servier: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; AbbVie: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; BMS: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Immune Design: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; TG Therapeutics, Inc.: Honoraria, Speakers Bureau; Janssen: Consultancy, Honoraria, Speakers Bureau; EUSA Pharma: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Kirin Kyowa: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; ADC Therapeutics: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Verastem: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Celltrion: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Janssen-Cilag: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Sandoz: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Merck: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Sanofi: Consultancy, Membership on an entity's Board of Directors or advisory committees; Incyte: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Roche: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Hutchings:Celgene, Genmab, Janssen, Novartis, F. Hoffmann-La Roche, Takeda: Research Funding; Genmab, F. Hoffmann-La Roche, Takeda: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees. Munoz:Juno/Celgene/BMS: Consultancy, Research Funding, Speakers Bureau; Alexion: Consultancy; Beigene: Consultancy, Speakers Bureau; Fosunkite: Consultancy; Innovent: Consultancy; Acrotech/Aurobindo: Speakers Bureau; Verastem: Speakers Bureau; AstraZeneca: Speakers Bureau; Kyowa: Consultancy, Honoraria, Speakers Bureau; Janssen: Consultancy, Research Funding, Speakers Bureau; Seattle Genetics: Consultancy, Honoraria, Research Funding, Speakers Bureau; Genentech/Roche: Research Funding, Speakers Bureau; AbbVie: Consultancy, Speakers Bureau; Merck: Research Funding; Portola: Research Funding; Incyte: Research Funding; Millenium: Research Funding; Pfizer: Consultancy; Kite, a Gilead Company: Consultancy, Research Funding, Speakers Bureau; Pharmacyclics: Consultancy, Research Funding, Speakers Bureau; Bayer: Consultancy, Research Funding, Speakers Bureau. Kim:JJ: Research Funding; Celltrion: Research Funding; Kyowa Kirn: Research Funding; Donga: Research Funding; Mundipharma: Research Funding; Pfizer: Research Funding; F. Hoffmann-La Roche: Research Funding. Advani:Astra Zeneca, Bayer Healthcare Pharmaceuticals, Cell Medica, Celgene, Genentech/Roche, Gilead, KitePharma, Kyowa, Portola Pharmaceuticals, Sanofi, Seattle Genetics, Takeda: Consultancy; Celgene, Forty Seven, Inc., Genentech/Roche, Janssen Pharmaceutical, Kura, Merck, Millenium, Pharmacyclics, Regeneron, Seattle Genetics: Research Funding. Ansell:Bristol Myers Squibb: Research Funding; Takeda: Research Funding; ADC Therapeutics: Research Funding; AI Therapeutics: Research Funding; Trillium: Research Funding; Affimed: Research Funding; Regeneron: Research Funding; Seattle Genetics: Research Funding. Younes:HCM: Consultancy; Daiichi Sankyo: Consultancy; Curis: Consultancy; BMS: Consultancy; Novartis: Consultancy; Epizyme: Consultancy; BioPath: Consultancy; AstraZeneca: Current Employment; Janssen: Consultancy; Takeda: Consultancy. Gallamini:Takeda: Other: Speaker. Liu:Takeda Pharmaceuticals: Current Employment. Little:Takeda: Current Employment, Current equity holder in publicly-traded company. Fenton:Seattle Genetics: Current Employment, Current equity holder in publicly-traded company. Fanale:Seattle Genetics: Current Employment, Current equity holder in publicly-traded company. Radford:GlaxoSmithKline: Current equity holder in publicly-traded company, Other: Spouse; AstraZeneca: Current equity holder in publicly-traded company, Other: Spouse; Takeda: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Pfizer: Research Funding; ADCT: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; BMS: Consultancy, Honoraria, Speakers Bureau; Novartis: Consultancy, Honoraria; Seattle Genetics: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau.

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.

Introduction: Novel approaches to treating patients (pts) with relapsed or refractory (R/R) classical Hodgkin lymphoma (cHL) have improved outcomes but some pts do not respond or, despite initial response, develop progressive disease and have limited treatment options. Camidanlumab tesirine (ADCT-301; Cami) is an antibody-drug conjugate composed of a human IgG1 anti-CD25 monoclonal antibody stochastically conjugated to a potent pyrrolobenzodiazepine (PBD) dimer warhead, which triggers cell death via formation of highly cytotoxic interstrand cross-links. Data from a Phase (Ph) 1 dose-escalation, dose-expansion trial demonstrated an overall response rate (ORR) in pts with cHL of 86.5% (48.6% complete response [CR] rate) at the 45 μg/kg dose. Cami had a generally acceptable safety profile at Ph 1 but there were 5/77 cases (6.5%) of Guillain-Barré syndrome (GBS)/polyradiculopathy (Preferred Terms: 4 GBS and 1 radiculopathy) (Collins et al, ICML June 18-22, 2019, Lugano, Switzerland, Abstract 055). Here, we present preliminary efficacy and safety results of a Ph 2 trial of single-agent Cami in pts with R/R cHL (NCT04052997). Methods: A single-arm, multi-center, open-label, Ph 2 trial is currently enrolling pts ≥16 yrs (US) and ≥18 yrs (outside US) with R/R cHL following ≥3 prior treatment lines (or ≥2 lines in pts ineligible for hematopoietic stem cell transplantation). Eligible pts had prior treatment with brentuximab vedotin and PD-1 blockade, measurable disease per 2014 Lugano Classification, and Eastern Cooperative Oncology Group performance status 0-2. The primary objective is to evaluate efficacy of single-agent Cami by ORR as determined by central review. Secondary objectives include further characterization of additional efficacy endpoints and safety. Pts receive 30-min IV infusions of Cami on Day 1 of each 3-week cycle at a dose of 45 μg/kg for 2 cycles, followed by 30 μg/kg for subsequent cycles for up to 1 yr or until discontinuation due to disease progression, unacceptable toxicity, or other reasons. Pts deriving clinical benefit at 1 yr may be able to continue treatment on a case-by-case basis. Treatment-emergent adverse events (TEAEs) were defined as AEs occurring/worsening from time of first dose to either 30 days post last dose or to start of new anticancer therapy/procedure, whichever occurs first. This analysis was conducted after meeting a protocol-specified criterion for pausing enrollment (≥2 cases of GBS or other relevant severe neurologic toxicity). Results: As of June 15, 2020, 47 pts with R/R cHL were enrolled and are included in this analysis. Median age was 36 (range 23-74) yrs and pts had received a median of 7 (range 3-20) lines of prior therapy, including transplant (Table 1). Pts received a median of 5 (range 2-10; mean 4.9 [SD 1.86]) cycles of Cami. ORR was 80.9% (38/47 pts), with 18 (38.3%) and 20 (42.6%) pts attaining CR and partial response, respectively; 6 pts (12.8%) had stable disease (Figure 1). TEAEs were experienced by all 47 pts; the most common (≥20% of pts) were fatigue (22, 46.8%); nausea, pyrexia, and maculopapular rash (18, 38.3% each); anemia and headache (12, 25.5% each); pruritus (11, 23.4%); arthralgia, constipation, diarrhea, hypophosphatemia, and rash (10, 21.3% each). TEAEs thought to be PBD-associated included skin reactions and nail disorders (36, 76.6%), liver function test abnormalities (14, 29.8%), and edema or effusion (7, 14.9%). There were 3 (6.4%) pts with GBS/polyradiculopathy (Preferred Terms: grade 4 subacute inflammatory demyelinating polyneuropathy, grade 2 radiculopathy, and grade 2 peripheral motor and sensory neuropathy updated to GBS after data cut-off date). In total, 27 (57.4%) pts had grade ≥3 TEAEs; the most common (≥5% of pts) were hypophosphatemia (6, 12.8%) and gamma-glutamyltransferase increased (3, 6.4%). Overall, 3 (6.4%) pts had TEAEs leading to dose reduction/delay and 6 (12.8%) pts had TEAEs leading to treatment discontinuation. Conclusions: Current data show that therapy with Cami has encouraging anti-tumor activity in heavily pretreated pts with R/R cHL. Safety was consistent with that reported at Ph 1, with no new safety concerns identified and similar incidence of GBS/polyradiculopathy. Following a positive risk-benefit assessment, the enrollment pause was lifted, and pts continue to be enrolled. Updated efficacy and safety results will be presented at the meeting. Funding: Study funded by ADC Therapeutics SA. Disclosures Herrera: Pharmacyclics: Research Funding; Bristol Myers Squibb: Consultancy, Other: Travel, Accomodations, Expenses, Research Funding; Merck: Consultancy, Research Funding; Gilead Sciences: Consultancy, Research Funding; Genentech, Inc./F. Hoffmann-La Roche Ltd: Consultancy, Research Funding; Seattle Genetics: Consultancy, Research Funding; Karyopharm: Consultancy; AstraZeneca: Research Funding; Immune Design: Research Funding. Carlo-Stella:Bristol-Myers Squibb, Merck Sharp & Dohme, Janssen Oncology, AstraZeneca: Honoraria; ADC Therapeutics and Rhizen Pharmaceuticals: Research Funding; Boehringer Ingelheim and Sanofi: Consultancy; Servier, Novartis, Genenta Science srl, ADC Therapeutics, F. Hoffmann-La Roche, Karyopharm, Jazz Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees. Collins:Taekda: Consultancy, Honoraria, Other: travel, accommodations, expenses, Speakers Bureau; Novartis: Consultancy, Honoraria, Speakers Bureau; Pfizer: Honoraria; Gilead: Consultancy, Honoraria, Speakers Bureau; ADC Therapeutics: Consultancy, Honoraria; BMS: Consultancy, Honoraria, Research Funding, Speakers Bureau; MSD: Consultancy, Honoraria, Research Funding; Celleron: Consultancy, Honoraria, Research Funding; Celgene: Research Funding; Amgen: Research Funding; BeiGene: Consultancy; Roche: Consultancy, Honoraria, Other: travel, accommodations, expenses , Speakers Bureau. Maddocks:Morphosys: Consultancy, Honoraria; BMS: Consultancy, Research Funding; Karyopharm: Consultancy; Seattle Genetics: Consultancy, Honoraria; ADC Therapeutics, AstraZeneca: Consultancy; Pharmacyclics: Consultancy, Honoraria; Celgene: Consultancy, Honoraria. Bartlett:Autolus: Research Funding; BMS/Celgene: Research Funding; Forty Seven: Research Funding; Immune Design: Research Funding; Seattle Genetics: Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Research Funding; Kite, a Gilead Company: Research Funding; Merck: Research Funding; Millennium: Research Funding; Pfizer: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Pharmacyclics: Research Funding; Seattle Genetics: Consultancy, Research Funding; Roche/Genentech: Consultancy, Research Funding; ADC Therapeutics: Consultancy; BTG: Consultancy; Acerta: Consultancy; Affimed Therapeutics: Research Funding. Savage:BeiGene: Other: Steering Committee; Roche (institutional): Research Funding; Merck, BMS, Seattle Genetics, Gilead, AstraZeneca, AbbVie: Honoraria; Merck, BMS, Seattle Genetics, Gilead, AstraZeneca, AbbVie, Servier: Consultancy. Caimi:ADCT, Kite Therapeutics, Genentech, Amgen, Verastem, TG Therapeutics, Bayer: Consultancy; ADC Therapeutics: Membership on an entity's Board of Directors or advisory committees; Genentech, ADC Therapeutics: Research Funding; Celgene: Speakers Bureau. Hess:ADC Therapeutics: Consultancy, Membership on an entity's Board of Directors or advisory committees; BMS, AstraZeneca: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Zinzani:ADC Therapeutics: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Sanofi: Consultancy, Membership on an entity's Board of Directors or advisory committees; Sandoz: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; EUSA Pharma: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Celltrion: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Verastem: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Janssen-Cilag: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Kirin Kyowa: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Merck: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Portola: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Janssen: Consultancy, Honoraria, Speakers Bureau; Servier: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Roche: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; TG Therapeutics, Inc.: Honoraria, Speakers Bureau; BMS: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Incyte: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Gilead: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; AbbVie: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; MSD: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Eusapharma: Consultancy, Speakers Bureau; Kyowa Kirin: Consultancy, Speakers Bureau; Immune Design: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Immune Design: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Cruz:ADC Therapeutics SA: Current Employment, Current equity holder in publicly-traded company. Wang:ADC Therapeutics America, inc: Current Employment, Current equity holder in publicly-traded company. Feingold:ADC Therapeutics: Current Employment, Current equity holder in publicly-traded company. Wuerthner:ADC Therapeutics SA: Current Employment, Current equity holder in publicly-traded company. Ansell:Takeda: Research Funding; Bristol Myers Squibb: Research Funding; Seattle Genetics: Research Funding; Regeneron: Research Funding; Trillium: Research Funding; ADC Therapeutics: Research Funding; Affimed: 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.

Abstract Diffuse large B-cell lymphoma (DLBCL) is a heterogeneous disease with recognized variability in clinical outcome, genetic features, and cells of origin. To date, transcriptional profiling has been used to highlight similarities between DLBCL tumor cells and normal B-cell subtypes and associate genes and pathways with unfavorable outcome. Given the genetic heterogeneity in DLBCL, there are likely to be subsets of tumors with different pathogenetic mechanisms and possible treatment targets. To identify DLBCL subtypes that were sufficiently robust to be captured by multiple methods, we analyzed the profiles of 176 newly diagnosed DLBCLs using three different clustering algorithms (hierarchical clustering (HC), self-organizing maps (SOM), and probabilistic clustering (PC)), the top 5% of genes with the highest reproducibility across duplicate samples and largest variation across patient tumors, and a resampling-based method (consensus clustering) that automatically selects the most stable numbers of clusters with each algorithm. Three discrete subsets of DLBCLs -- “Oxidative Phosphorylation” (OxPhos), “B-cell Receptor/Proliferation” and “Host Response” (HR) -- were identified, characterized using gene set enrichment analysis and confirmed in an independent series of newly diagnosed DLBCLs with available array data. There was an association between cluster membership and examined genetic abnormalities in DLBCL. BCL2 translocations were more common in the OxPhos cluster whereas BCL6 translocations were more frequent in the BCR/proliferation cluster. Translocations of either type were uncommon in the HR cluster. Patients with HR DLBCLs were also significantly younger than those with OxPhos or BCR/proliferation tumors; HR patients also had a significantly higher incidence of splenic and BM involvement. The unique characteristics of HR tumors - fewer known genetic abnormalities and prominent host immune and inflammatory cell transcripts -prompted us to assess host immune cells in study tumors using morphologic and immunohistochemical approaches. HR DLBCLs contained significantly higher numbers of morphologically distinct CD2+/CD3+ tumor-infiltrating lymphocytes and interdigitating S100+/GILT+/CD1a-/CD123- dendritic cells. The HR cluster shared features of histologically defined T-cell/histiocyte-richBCL, including fewer known genetic abnormalities, younger age at presentation and frequent splenic and bone marrow involvement. The current study identifies tumor microenvironment and host inflammatory response as defining features in DLBCL, provides insights into the nature of the host immune response in a major DLBCL subtype and suggests rational treatment targets in newly identified tumor groups.

Abstract Primary mediastinal large B-cell lymphoma (MLBCL) is a clinically distinct entity that typically presents as localized, sclerotic disease in young, female patients. We previously characterized the transcriptional profiles of MLBCLs and identified important shared features with a clinically related disorder, classical Hodgkin lymphoma (cHL) (Blood 102:3871, 2003). Given the documented role of the NFkB survival pathway in Hodgkin Reed-Sternberg cells, we previously assessed NFkB activation in MLBCL by determining the subcellular location of the c-REL subunit of the NFkB heterodimer with a 2-color immunofluoresence assay. In a small pilot MLBCL series, c-REL was localized to the nucleus in the majority of examined cases, consistent with NFkB activation. In the current study, we evaluated c-REL subcellular localization in an additional series of MLBCLs and DLBCLs using a broadly applicable immunoperoxidase method. 100% of MLBCLs exhibited nuclear c-REL staining whereas DLBCL c-REL subcellular localization was more variable. Thereafter, we analyzed the transcription profiles of the 34 MLBCLs and 176 DLBCLs for coordinate expression of NFkB target genes, using literature-curated NFkB target gene lists from three independent sources and gene set enrichment analysis (GSEA). MLBCL signatures exhibited significant enrichment of 2 of the 3 NFkB target gene sets. In addition, 32 NFkB target genes from the combined set were significantly more abundant in MLBCLs than DLBCLs (> 30% more abundant and > 99th percentile in permutation analysis). Similar results were obtained in an independent series of MLBCLs and DLBCLs with available gene expression profiles (J. Exp. Med. 198:851, 2003). To assess the role of c-REL amplification in NFkB activation in our lymphoma series, we compared c-REL amplification, c-REL subcellular localization and coordinate expression of the identified NFkB target genes and classified the DLBCLs according to putative cell of origin. The majority of c-REL amplifications (67%) were found in DLBCLs of germinal center (GC) subtype, consistent with the observation that c-REL is part of the described GC signature. However, most (71%) of the examined GC DLBCLs had cytoplasmic c-REL expression and the GC DLBCLs did not have increased expression of NFkB target genes. Taken together with the MLBCL analyses, these studies indicate that: 1) NFkB is consistently activated in MLBCL; 2) c-REL amplification is not closely associated with NFkB activation in large cell lymphomas (LCLs); and 3) NFkB activation in LCL subtypes does not require amplification of the c-REL locus.

8060 Background: ENKL is a rare and aggressive subtype of peripheral T-cell lymphoma. Due to its geographic predilection there is a paucity of data on clinical experiences from non-Asian countries. The purpose of this study was to analyze characteristics and outcomes of patients (pts) with ENKL identified from major academic centers in NA. Methods: Pts with newly diagnosed CD56+ ENKL were retrospectively identified. Analyses included disease characteristics, ethnicity, therapy, and outcomes. Results: 115 pts (63.5% Caucasian, 20% Asian, 16.5% other) were identified across 10 centers diagnosed between 5/1990-5/2011 (Era 1: pre-2000, n=16; Era 2: 2000-2005, n=45; Era 3: post-2005, n=54). Median age was 52 years (19-88). 75 (65%) had stage I/II disease and were treated with combined modality therapy (CMT) n=48, chemotherapy (CT) n=14 or radiotherapy (RT) n=14. 40 pts had stage III/IV disease and were treated with CT (n=23), CMT (n=12) or RT (n=5). CT regimens used alone or in CMT were either anthracycline-based (n=68) or other (n=29). 63% of stage I/II pts and 40% with stage III/IV achieved complete remission (CR). 30 pts underwent a stem cell transplant (SCT); 14 in first CR and 16 at progression/relapse (autologous, n=21; allogeneic, n=9). Pts with stage I/II disease had a better progression-free survival (PFS) and overall survival (OS) compared with stage III/IV (12 vs 5.2 months (p=0.003) and 41.5 vs 8.9 months (p<0.0001), respectively). For all stages, treatment with CMT compared with CT or RT alone was also associated with better PFS and OS, 18.0 vs 3.9 months (p<0.0001), and 41.5 vs 10.2 months (p=0.002) respectively. Non-anthracycline-based regimens were associated with better PFS (p=0.001) and OS (p=0.045). No survival differences were seen between Asian and non-Asian pts. Conclusions: This series represents one of the largest experiences of ENKL in NA. Our data are consistent with Asian studies in: 1) majority of pts present with early stage disease; 2) overall poor outcome; 3) superiority of CMT and non-anthracycline regimens. Advances in understanding biology and international collaborative efforts are required to improve outcome in this rare entity.

Abstract The phase 3 ECHELON-1 study demonstrated that brentuximab vedotin (A) with doxorubicin, vinblastine, and dacarbazine (AVD; A+AVD) exhibited superior modified progression-free survival (PFS) vs doxorubicin, bleomycin, vinblastine, and dacarbazine (ABVD) for frontline treatment of patients with stage III/IV classical Hodgkin lymphoma (cHL). Maturing positron emission tomography (PET)-adapted trial data highlight potential limitations of PET-adapted approaches, including toxicities with dose intensification and higher-than-expected relapse rates in PET scan after cycle 2 (PET2)-negative (PET2−) patients. We present an update of the ECHELON-1 study, including an exploratory analysis of 3-year PFS per investigator. A total of 1334 patients with stage III or IV cHL were randomized 1:1 to receive 6 cycles of A+AVD (n = 664) or ABVD (n = 670). Interim PET2 was required. At median follow-up of 37 months, 3-year PFS rates were 83.1% with A+AVD and 76.0% with ABVD; 3-year PFS rates in PET2− patients aged &lt;60 years were 87.2% vs 81.0%, respectively. A beneficial trend in PET2+ patients aged &lt;60 years on A+AVD was also observed, with a 3-year PFS rate of 69.2% vs 54.7% with ABVD. The benefit of A+AVD in the intent-to-treat population appeared independent of disease stage and prognostic risk factors. Upon continued follow-up, 78% of patients with peripheral neuropathy on A+AVD had either complete resolution or improvement compared with 83% on ABVD. These data highlight that A+AVD provides a durable efficacy benefit compared with ABVD for frontline stage III/IV cHL, consistent across key subgroups regardless of patient status at PET2, without need for treatment intensification or bleomycin exposure. This trial was registered at www.clinicaltrials.gov as #NCT01712490 (EudraCT no. 2011-005450-60).

Abstract Introduction: Nivolumab, a fully human IgG4 monoclonal antibody targeting programmed death receptor-1, has recently been FDA approved for classical Hodgkin lymphoma (cHL) that has relapsed or progressed after autologous stem cell transplantation (ASCT) and post-transplantation brentuximab vedotin (BV). CheckMate 205 (NCT02181738) is a phase 2, international, multicohort study evaluating nivolumab monotherapy in patients with cHL after failure of ASCT. At minimum 6 months' follow-up of Cohort B (205B) which included patients who had received BV after disease recurrence following ASCT, objective response rate (ORR) per independent radiologic review committee (IRRC) was 66% and 6-month progression-free survival (PFS) was 77%, with an acceptable safety profile (Younes et al. Lancet Oncol 2016; Jul 20 [Epub ahead of print]). Here we report outcomes with longer follow-up (minimum 12-month follow-up) in 205B. Primary results from Cohort A, which enrolled patients who relapsed after ASCT but were BV-naïve, will also be presented for the first time as data were not available at time of abstract submission. Methods: CheckMate 205 was designed to evaluate the efficacy and safety of nivolumab monotherapy in patients with cHL who relapsed after ASCT in 3 cohorts: 205A (BV-naive patients; n = 63); 205B (BV after failed ASCT; n = 80); 205C (BV at any time prior to study drug; n = 100). Nivolumab was given at 3 mg/kg intravenously every 2 weeks until disease progression or unacceptable toxicity in 205A and 205B. The primary endpoint was IRRC-assessed ORR. Results: 80 patients were treated in Cohort 205B; the median age was 37 years (range 18-72). Patients had received a median of 4 prior regimens (range 3-15). At data cut-off (April 2016) with median duration of follow-up of 15.4 months (range 1.9-18.5), 43 patients (54%) still remained on therapy. IRRC-assessed ORR for patients in 205B was 68% (95% confidence interval [CI], 56%, 78%). CR and partial response (PR) rates per IRRC were 8% (3%, 16%) and 60% (48%, 71%), respectively. With longer follow-up, the median duration of response was prolonged to 13.1 months (95% CI, 8.7, not reached; range, 0.0+, 14.2+). The median duration of CR (DOCR) was not reached (95% CI, 4.6, not available [NA]; range, 0.7+, 10.4+) and the median duration of PR was 13.1 months (95% CI, 7.79, NA; range, 0.0+, 13.4+) (Table 1). IRRC median PFS was 14.8 months (95% CI, 11.3 months, NA); 12-month PFS was 54.6% (95% CI, 40.9%, 66.4%), and 12-month overall survival (OS) was 94.9% (median OS not reached). Of 37 patients (46%) who discontinued nivolumab, the most common reasons were disease progression (n = 19 [24%]), allogeneic stem cell transplant (n = 7 [9%]) and adverse events (n = 5 [6%]). Seventy-four patients (93%) had drug-related adverse events (AEs) of any grade. The most common drug-related AEs were fatigue (28%), infusion reaction (20%), arthralgia (15%), and rash (15%). 29% of patients had Grade 3-4 drug-related AEs; the most common were increased lipase (8%), neutropenia (5%), and increased aspartate aminotransferase (4%). The most common serious AEs were pyrexia, pneumonia, tumor progression, arrhythmia, infusion reaction, and meningitis (≤4% each). Conclusions: In this report with extended 12-month follow-up, longer remissions are noted following nivolumab monotherapy in relapsed cHL, including durable PRs in heavily pretreated patients. Nivolumab has an acceptable safety profile, similar to previously reported. Primary results following nivolumab monotherapy in BV-naïve patients with cHL who progressed after ASCT (Cohort 205A) will also be presented at the meeting. Study funding: Study funded by Bristol-Myers Squibb. Professional writing assistance was provided by K. Jesien of Caudex and funded by Bristol-Myers Squibb. Disclosures Timmerman: Seattle Genetics, Genmab, Celgene: Consultancy, Honoraria; Bristol-Myers Squibb, Kite Pharma, Valor Biopharmaceuticals, Janssen: Research Funding. Engert:Takeda, BMS: Consultancy, Honoraria, Research Funding. Armand:Bristol-Myers Squibb: Consultancy, Research Funding; Pfizer: Research Funding; Roche: Research Funding; Infinity Pharmaceuticals: Consultancy; Merck: Consultancy, Research Funding; Sequenta Inc: Research Funding. Collins:Takeda: Consultancy, Honoraria, Speakers Bureau. Kuruvilla:Roche Canada: Consultancy, Honoraria, Research Funding; Janssen: Consultancy, Honoraria; Abbvie: Consultancy, Honoraria; Amgen: Honoraria; Merck: Honoraria; BMS: Consultancy, Honoraria; Celgene: Consultancy, Honoraria; Gilead: Consultancy, Honoraria; Seattle Genetics: Consultancy, Honoraria; Lundbeck: Honoraria. Cohen:Millennium/Takeda: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees; Infinity: Consultancy, Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Pharmacyclics: 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; Bristol-Myers Squibb: Research Funding. Trneny:Roche, Celgene, Takeda, Janssen, Gilead, Bristol-Myers Squibb: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Roche, Celgene: Research Funding. De Boer:NKI-AVL: Employment. Shipp:Cell Signaling: Honoraria; Merck, Gilead, Takeda: Other: Scientific Advisory Board; Bayer: Research Funding; Bristol-Myers Squibb: Consultancy, Research Funding. Rodig:Bristol-Myers Squibb: Honoraria, Research Funding; Perkin Elmer: Membership on an entity's Board of Directors or advisory committees. Kato:Bristol-Myers Squibb: Employment. Sumbul:Bristol-Myers Squibb: Employment. Ansell:BMS, Seattle Genetics, Merck, Celldex and Affimed: Research Funding.