Enschede, Sari H.

Abstract Background: The anti-apoptotic proteins BCL-2 and MCL-1 promote multiple myeloma (MM) cell survival. Bortezomib (BTZ) can inhibit MCL-1 activity by stabilizing the MCL-1 antagonist, NOXA. Venetoclax is an orally bioavailable, highly selective BCL-2 inhibitor, which enhances BTZ efficacy in MM xenograft models. This Phase 1 study evaluates venetoclax with BTZ and dexamethasone (Dex) in patients (pts) with relapsed/refractory MM. Methods: Objectives include safety, pharmacokinetics, preliminary efficacy and maximum therapeutic dose of venetoclax with BTZ and Dex. A fixed dose of venetoclax ranging from 50 to 800 mg PO daily, according to dose cohort assignment, was given in combination in cycles (C) 1-11 and alone in C12 and beyond. Dose escalation decisions were made using the continual reassessment method. Pts received BTZ (1.3 mg/m2 SC, days [D] 1, 4, 8, 11) and Dex (20 mg PO, D1, 2, 4, 5, 8, 9, 11, 12) in cycles (C)1-8 (21D), then BTZ + Dex (D1, 8, 15, 22) in C9-11 (35D). Results: Forty-one pts were enrolled as of June 15, 2015 (pts in each cohort: 50 mg, n=3; 100 mg, n=5; 200 mg, n=6; 300 mg, n=7; 400 mg, n=6; 500 mg, n=7; 600 mg, n=5; 800 mg, n=2). Median age was 65 (38-79); 15/26 F/M. 14 were ISS stage I, 11 stage II, 11 stage III, 5 missing. Median (range) number of prior lines of therapy was 5 (1-15). Thirty-five pts had received prior BTZ (10 refractory), 34 prior lenalidomide (22 refractory); 29 had undergone stem cell transplantation. Based on FISH analysis, 5 pts had MM with t(11;14); 3 with t(4;14), 20 with del 17p, and 10 with del 13q. Treatment-emergent AEs occurring in ≥20% of pts were constipation (37%), diarrhea (37%), thrombocytopenia (32%), asthenia (29%), insomnia (29%), anemia (27%), peripheral neuropathy (27%), dyspnea (24%), peripheral edema (22%), and nausea (20%). Grade 3/4 AEs in ≥10% of pts were thrombocytopenia (20%), and anemia (17%). SAEs occurred in 18 pts; SAEs in ≥2 pts were cardiac failure, embolism, pyrexia, respiratory failure, sepsis, thrombocytopenia (n=2 each, no SAEs were venetoclax-related). Twenty-nine pts have discontinued treatment: 23 due to PD, 2 due to AEs [adenocarcinoma; cardiac and respiratory decompensation attributed to Dex (DLT at 300 mg)], and 4 withdrew consent. Three deaths occurred (all due to PD). No TLS occurred. In preliminary PK analyses (n=41), dose-normalized venetoclax exposure when given with BTZ+Dex was similar when compared to venetoclax monotherapy in MM as well as CLL and NHL pts. Forty of 41 pts were evaluable for efficacy. All responses occurred in BTZ sensitive or naïve pts. Median (range) duration or response was 5.9 (0-14.1) months in all pts, 8.5 (2.3-11.4) months in BTZ naïve pts, and 4.7 (0-14.1) months in BTZ-sensitive pts. Conclusions: Venetoclax with BTZ and Dex has an acceptable safety profile in heavily pretreated MM pts; no new safety signals were identified compared to other venetoclax studies. These early data suggest the combination of proteasome and BCL-2 inhibition resulted in anti-tumor activity. Responses were observed only in pts naïve or sensitive to prior BTZ (ORR = 100% and 58%, respectively) and occurred in all dose cohorts. The study is currently enrolling pts in the 1000 mg dose escalation cohort. Figure 1. Figure 1. Disclosures Moreau: Celgene, Janssen, Takeda, Novartis, Amgen: Membership on an entity's Board of Directors or advisory committees. Off Label Use: Venetoclax is an investigational drug that is not yet approved in this indication. Roberts:AbbVie and Genentech: Research Funding; Walter and Eliza Hall Institute of Medical Research: Employment. Agarwal:Amgen, Millennium: Consultancy; Celgene, Onyx: Speakers Bureau; AbbVie: Research Funding. Facon:Celgene: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Janssen: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Millenium: Membership on an entity's Board of Directors or advisory committees; Onyx: Membership on an entity's Board of Directors or advisory committees; BMS: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees; Amgen: Membership on an entity's Board of Directors or advisory committees; Pierre Fabre: Membership on an entity's Board of Directors or advisory committees. Kumar:Skyline, Noxxon: Honoraria; Celgene, Millennium, Onyx, Janssen, Noxxon, Sanofi, BMS, Skyline: Consultancy; Celgene, Millennium, Onyx, Novartis, Janssen, Sanofi: Research Funding. Touzeau:AbbVie: Research Funding. Darden:AbbVie: Employment, Equity Ownership. Morris:AbbVie: Employment, Equity Ownership. Ross:AbbVie: Employment, Equity Ownership. Salem:AbbVie: Employment, Equity Ownership. Munasinghe:AbbVie: Employment, Equity Ownership. Zhu:AbbVie: Employment, Equity Ownership. Leverson:AbbVie: Employment, Equity Ownership. Maciag:AbbVie: Employment, Equity Ownership. Enschede:AbbVie: Employment, Equity Ownership. Verdugo:AbbVie: Employment, Equity Ownership. Humerickhouse:AbbVie: Employment, Equity Ownership. Harrison:Celgene: Honoraria, Research Funding; Janssen: Research Funding, Speakers Bureau; AbbVie: Research Funding.

Abstract Background: The anti-apoptotic protein BCL-2 has been implicated in mediating the survival of multiple myeloma (MM) cells. Venetoclax is a potent, selective, orally bioavailable small-molecule BCL-2 inhibitor. Venetoclax induces cell death in MM cell lines in vitro and primary MM samples ex vivo. Certain genetic subtypes of MM cells are particularly sensitive to venetoclax, including t(11;14) cells, which express a high ratio of BCL2 to MCL1 (venetoclax resistance factor). The current Phase 1 study evaluates safety, efficacy, and pharmacokinetics (PK) in patients (pts) with relapsed/refractory MM. Methods: Primary objectives are to evaluate safety, PK, and recommended phase two dose; other objectives include assessing preliminary efficacy and the impact of chromosomal abnormalities. In dose-escalation (DE) cohorts, venetoclax was given orally daily at 300, 600, 900, or 1200 mg after a 2-week dose ramp-up (3+3 design). Patients in the safety expansion (SE) cohort received 1200 mg daily after ramp-up. All patients were monitored for tumor lysis syndrome (TLS). Results: As of June 17, 2015, 37 patients were enrolled in the study: 30 from DE cohorts and 7 from the SE. Median (range) age was 66 years; 19 (51%) were female. Fourteen were ISS stage I, 13 stage II, 8 stage III, 2 unknown. The median (range) number of prior lines of therapy was 6 (1-19). Thirty-two had prior bortezomib (20 refractory), 35 lenalidomide (18 refractory), and 26 had prior stem cell transplant. Fourteen patients had t(11;14), 4 had t(4;14), 5 had del 17p, and 17 had del 13q. Adverse events (AEs) in ≥20% of patients were nausea (49%), diarrhea (38%), vomiting (30%), anemia (27%), fatigue (24%). Grade 3/4 AEs (≥10%): thrombocytopenia (22%), anemia (19%), neutropenia (11 %). Serious AEs (≥2 patients): pyrexia (n=3), cough, malignant neoplasm progression, and sepsis (2 each); 2 (upper abdominal pain and anemia) were possibly related to venetoclax. Thirty (81%) patients have discontinued venetoclax: 24 due to PD, 3 for AEs (worsening shortness of breath, hypokalemia, and nausea), 2 withdrew consent, 1 due to death (brain hemorrhage following injury). Four deaths occurred (2 due to PD, 1 due to brain hemorrhage, 1 due to pneumopathy). Two of the 6 patients in the 600 mg cohort experienced DLTs of upper abdominal pain and nausea with abdominal pain. No patients met the criteria for laboratory or clinical TLS. Based on preliminary PK (n=21), the mean Cmax and AUC24 were ~dose-proportional at all studied doses (300, 600, 1200 mg) except 900 mg, and dose-normalized venetoclax exposure in MM was similar to that in CLL and NHL pts. Thirty-two of the 37 patients were evaluable for preliminary efficacy (Table). Two patients, both t(11;14), achieved a complete response (1 at 600 mg and 1 at 900 mg). Responses were first achieved at 1.8 and 1.1 months and were maintained for 9.7 and 9.0 months, respectively (900 mg pt remains in CR). Among the 16 patients receiving 1200 mg in the DE or SE cohort, 6 of whom had t(11;14), 5 achieved SD, 6 experienced PD, and 5 are not yet evaluable. Conclusions: Venetoclax monotherapy had a tolerable safety profile in heavily-pretreated relapsed/refractory MM, and no new safety signals were observed compared to other venetoclax studies. The study continues to enroll in the SE cohort at 1200 mg. Responses (including CR) and longer time on venetoclax were observed in t(11;14) patients. These early results suggest that venetoclax has single agent activity, most prominently in t(11;14) patients. Figure 1. Figure 1. Disclosures Kumar: Celgene: Research Funding; Millenium/Takeda: Research Funding; Onyx: Research Funding; AbbVie: Research Funding; Janssen: Research Funding; Sanofi: Research Funding; Celgene, Millenium, Sanofi, Skyline, BMS, Onyx, Noxxon,: Other: Consultant, no compensation,; Skyline, Noxxon: Honoraria. Off Label Use: Venetoclax is an investigational drug that is not yet approved in this indication.. Vij:Takeda, Onyx: Research Funding; Celgene, Onyx, Takeda, Novartis, BMS, Sanofi, Janssen, Merck: Consultancy. Kaufman:Janssen: Consultancy; Spectrum: Consultancy; Merck: Research Funding; Celgene: Consultancy; Onyx: Consultancy; Novartis: Consultancy; Novartis: Research Funding; Onyx: Research Funding. Mikhael:Sanofi: Research Funding; AbbVie: Research Funding; Celgene: Research Funding; Onyx: Research Funding. Moreau:Takeda: Other: Adboard; Janssen: Other: Adboard; Celgene: Other: Adboard; Novartis: Other: Adboard; Amgen: Other: Adboard. Alzate:AbbVie: Employment, Equity Ownership. Morris:AbbVie: Employment, Equity Ownership. Ross:AbbVie: Employment, Equity Ownership. Dunbar:AbbVie: Employment, Equity Ownership. Zhu:AbbVie: Employment, Equity Ownership. Maciag:AbbVie: Employment, Equity Ownership. Agarwal:AbbVie: Employment, Equity Ownership. Leverson:AbbVie: Employment, Equity Ownership. Enschede:AbbVie: Employment, Equity Ownership. Humerickhouse:AbbVie: Employment, Equity Ownership. Touzeau:AbbVie: Research Funding.

Key Points Venetoclax monotherapy at a daily dose up to 1200 mg has an acceptable safety profile in patients with relapsed/refractory MM. Venetoclax monotherapy has demonstrated antimyeloma activity in patients with relapsed/refractory MM positive for t(11;14).

Key Points In relapsed/refractory MM, venetoclax plus bortezomib and dexamethasone appears to be safe and efficacious. This is a novel therapeutic approach for MM.