Cramer, Stuart

ABSTRACT Background Nab ‐sirolimus (ABI‐009, nab ‐rapamycin; Aadi Bioscience Inc. [Aadi]) is a human albumin‐bound form of sirolimus nanoparticles, a potent mTOR inhibitor. This phase I trial was conducted to define dose‐limiting toxicities (DLT), maximum tolerated or recommended phase II dose (MTD/RP2D), and pharmacokinetics of Nab ‐sirolimus in combination with temozolomide and irinotecan. Methods Using a rolling 6 design, Nab ‐sirolimus was administered intravenously (IV) on days (D) 1 and 8 of cycle (C) 1. In subsequent cycles, Nab ‐sirolimus was administered D1 and D8 in combination with temozolomide (125 mg/m 2 /dose, maximum 250 mg/dose) and irinotecan (90 mg/m 2 /dose) orally, daily on D1–5. Cycle duration was 21 days. Three dose levels (DL) of Nab ‐sirolimus were investigated (DL1: 35 mg/m 2 /dose, DL‐1: 20 mg/m 2 /dose, and DL‐2: 15 mg/m 2 /dose). The observation period for estimating the MTD/RP2D was defined by cycles 1 and 2. Results Thirty‐three patients were enrolled, 32 were eligible. Dose determination included 17 evaluable patients, median (range) age 12 (2–20) years and six additional patients were enrolled (four evaluable for toxicity) on a pharmacokinetic cohort. C1 or C2 DLTs were primarily thrombocytopenia including 2/5 patients at DL1, 2/6 patients at DL‐1, and 1/6 patients at DL‐2. One patient (DL1) with Ewing Sarcoma had a partial response and remained on study for 35 cycles. Rapamycin clearance was dose dependent. Irinotecan clearance and its active metabolite SN‐38 exposure were not affected by coadministration with Nab ‐sirolimus. Conclusion The MTD for Nab ‐sirolimus was 15 mg/m 2 /dose IV on D1 and D8 in combination with temozolomide 125 mg/m 2 /dose and oral irinotecan 90 mg/m 2 /dose daily for 5 days during 21D cycles. Trial Registration ClinicalTrials.gov identifier NCT02975882

10022 Background: nab-Sirolimus (formerly know ABI-009 and nab-rapamycin) is a novel human albumin-bound preparation of sirolimus, a potent mTOR inhibitor. We report results of a Phase I study of ABI-009 alone and in combination with irinotecan and temozolomide in children with relapsed/refractory solid or CNS tumors. Methods: Patients (age 1-21 years) with relapsed/refractory solid or CNS tumors were eligible. Using a rolling 6 design, ABI-009 was administered intravenously as a single agent on Days 1 and 8 of cycle 1 (cycle = 21d), then subsequent cycles ABI-009 was administered in combination with temozolomide (125 mg/m2/dose, maximum 250 mg/dose) orally once daily x 5 on Days 1-5 and irinotecan 90 mg/m2/dose orally once daily x 5 on Days 1-5. Three dose levels (DL) of ABI-009 were investigated (DL1: 35mg/m2/dose, DL-1: 20mg/m2/dose, and DL-2: 15mg/m2/dose). The maximum tolerated dose (MTD) or Recommended Phase 2 Dose (RP2D) was established based on dose limiting toxicity (DLT) observed during Cycle 1 and 2. At the RP2D, additional patients were enrolled for pharmacokinetics (PK). Results: 33 patients were enrolled (32 eligible and 1 ineligible); 11 did not experience DLT but were not evaluable for toxicity due to progressive disease or physician decision to discontinue protocol therapy prior to completion of cycle 2; 17 [median age 13 (2-20) years] were evaluable for determination of MTD during dose escalation, 6 were enrolled on the PK cohort, of which 3 were evaluable to toxicity. At DL1, 2/5 patients experienced DLT (thrombocytopenia during cycle 1 (n = 1) and cycle 2 (n = 1)); at DL-1, 2/6 patients experienced DLT (thrombocytopenia in cycle 1); at DL-2, 1/6 patients experienced DLT (thrombocytopenia in cycle 1). PK expansion enrolled at DL-2 and 1/3 participants evaluable for toxicity had a DLT (mucositis). Overall, at DL-2, 2/9 patients (22%) had DLT. One patient with Ewing Sarcoma had a partial response and remained on study for 35 cycles; Patients (one each) with Ewing Sarcoma, Wilms Tumor, and Pineoblastoma had stable disease, ranging from 3-6 cycles. Conclusions: Thrombocytopenia was dose limiting for ABI-009 alone and in combination with temozolomide and irinotecan. The MTD for ABI-009 is 15mg/m2/dose days 1 and 8 in combination with 5 daily doses of temozolomide 125 mg/m2/dose and oral irinotecan 90 mg/m2/dose. One patient had a partial response, 3 patients had prolonged stable disease. Pharmacokinetics and pharmacodynamics are pending and will inform future trials. Clinical trial information: NCT02975882.

Abstract Background Denintuzumab mafodotin (SGN-CD19A) is an antibody-drug conjugate (ADC) composed of a humanized anti-CD19 monoclonal antibody conjugated to the microtubule-disrupting agent monomethyl auristatin F (MMAF) via a maleimidocaproyl linker. CD19 is a B cell-specific marker that is expressed in nearly all patients (pts) with B-lineage acute leukemia or lymphoma. Methods A phase 1 dose-escalation study is ongoing to evaluate the safety, tolerability, pharmacokinetics, and antitumor activity of denintuzumab mafodotin in pts with relapsed or refractory (R/R) B-ALL, B-cell lymphoma (B-LBL), or Burkitt leukemia/lymphoma (NCT 01786096). Eligible pts are ≥1 year of age and are R/R to ≥1 prior systemic regimen; patients with Philadelphia chromosome-positive (Ph+) disease must have failed a 2nd-generation TKI. A modified continual reassessment method was used for dose allocation and maximum tolerated dose (MTD) estimation. The study evaluated 2 dosing schedules: first weekly (Days 1 and 8 of 21-day cycles) and then once every 3 weeks (q3wk). This report presents data from the adult subset of pts in the study (≥18 years). Results To date, 71 adult pts with R/R B-ALL (n=59), B-LBL (n=6) or Burkitt leukemia/lymphoma (n=6) have been treated; median age is 45 years (range 18−77). Pts received a median of 2 prior therapies (range 1−8); 20 pts (28%) had prior allogeneic stem cell transplant. On the weekly schedule (0.3−3 mg/kg), 40 pts received a median of 2 cycles (range 1−27); 2 pts remain on treatment. On the q3wk schedule (4−6 mg/kg), 31 pts received a median of 3 cycles (range 1−6); 4 pts remain on treatment. An MTD was identified at 5 mg/kg q3wk and was not reached with weekly dosing. Best clinical responses to date for pts with B-ALL are summarized below: Table 1.Response category per Cheson 2003Efficacy-evaluable adult pts with B-ALLweekly dosing, N=32 n (%)q3wk dosing, N=23 n (%)Complete remission (CR)6 (19)3 (13)CR with incomplete platelet recovery (CRp)−3 (13)CR with incomplete blood recovery (CRi)−2 (9)Partial remission (PR)1 (3)−Resistant disease with clinical benefit15 (47)12 (52)Resistant disease without clinical benefit2 (6)-Progression8 (25)3 (13)CRc (CR+CRi+CRp), % (95% CI)19% (95% CI 7, 36)35% (95% CI 16, 57) In the q3wk schedule, the CRc rate was similar at 4, 5, and 6 mg/kg. The median duration of response across schedules is currently 27 weeks (95% CI 7, −). Of 12 pts with CRc and available minimal residual disease (MRD) assessment, 7 were MRD negative. 3 patients with MRD-negative CRs have been in remission for >1 year, 2 of whom have been on continuous treatment for 19 and 22 months. In the subset of pts with Ph+ B-ALL, 4 of 8 pts achieved CR and 1 pt a PR. In 6 pts with Burkitt leukemia/lymphoma, 1 achieved a CR. In 6 pts with B-LBL, objective responses were 1 CR and 2 PR. The adverse event (AE) profiles were similar across both dosing schedules; the most frequently reported AEs were pyrexia (54%), nausea (52%), fatigue (51%), headache (44%), chills (38%), vomiting (37%), blurred vision (35%), and anemia (34%). Ocular symptoms and corneal exam findings consistent with superficial microcystic keratopathy were observed in 40 pts (56%); symptoms were less severe than the associated corneal exam findings. Keratopathy was managed with topical steroids and dose modifications, and improved/resolved within a median of ~3 wks (range 1-17) in pts with sufficient follow-up. ADC exposures increased with dose, and in leukemia patients, target-mediated disposition was observed that diminished with higher doses in the q3wk schedule. Post treatment, flow cytometry data demonstrate that unbound CD19 on peripheral blasts inversely correlates with ADC concentration in circulation, and is present in the majority of evaluable patients at the end of the q3wk cycle. Conclusions Denintuzumab mafodotin is generally well tolerated and demonstrates activity in heavily pretreated adult pts with B-ALL and B-lineage highly aggressive lymphomas, including durable MRD-negative responses. The results of this trial indicate that the q3wk schedule, with a CRc rate of 35% in B-ALL, warrants further clinical investigation. Based on the encouraging responses observed to date in Ph+ B-ALL (CRs in 4 of 8 pts), an expansion cohort of these pts is currently enrolling on the q3wk schedule. Disclosures Fathi: Exelexis: Research Funding; Agios: Membership on an entity's Board of Directors or advisory committees; Merck: Membership on an entity's Board of Directors or advisory committees; Seattle Genetics: Membership on an entity's Board of Directors or advisory committees, Research Funding; Ariad: Consultancy; Takeda Pharmaceuticals International Co.: Research Funding. Off Label Use: SGN-CD19A is an investigational agent being studied in patients with B-cell malignancies. SGN-CD19A is not approved for use.. Borate:Seattle Genetics: Research Funding; Genoptix: Consultancy; Alexion: Speakers Bureau; Gilead: Speakers Bureau; Novartis: Speakers Bureau; Amgen: Speakers Bureau. DeAngelo:Agios: Consultancy; Incyte: Consultancy; Celgene: Consultancy; Amgen: Consultancy; Pfizer: Consultancy; Bristol Myers Squibb: Consultancy; Ariad: Consultancy; Novartis: Consultancy. O'Brien:Seattle Genetics, Inc.: Research Funding. Trippett:OSI Pharmaceuticals: Research Funding; Seattle Genetics, Inc.: Research Funding. Shah:NCCN: Consultancy; SWOG: Consultancy; Seattle Genetics: Research Funding; Acetylon Pharmaceuticals, INC: Membership on an entity's Board of Directors or advisory committees; Pharmacyclics: Speakers Bureau; Bayer: Honoraria; Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Janssen: Speakers Bureau; DeBartolo Institute for Personlaized Medicine: Research Funding; Rosetta Genomics: Research Funding; Plexus Communications: Honoraria; Spectrum: Speakers Bureau. Hale:Seattle Genetics, Inc.: Research Funding; Hyundai: Research Funding; V Foundation: Research Funding. Silverman:Seattle Genetics, Inc.: Research Funding. Pauly:Seattle Genetics, Inc.: Research Funding. Kim:Bayer: Consultancy; Seattle Genetics, Inc.: Consultancy, Research Funding; Eli Lilly: Consultancy. Kostic:Seattle Genetics, Inc.: Employment, Equity Ownership. Huang:Seattle Genetics, Inc.: Employment, Equity Ownership. Pan:Seattle Genetics, Inc.: Employment, Equity Ownership. Chen:Genentech: Consultancy, Speakers Bureau; Seattle Genetics, Inc.: Consultancy, Other: Travel expenses, Research Funding, Speakers Bureau; Millennium: Consultancy, Research Funding, Speakers Bureau.