The Single-Agent Bcl-2 Inhibitor ABT-199 (GDC-0199) In Patients With Relapsed/Refractory (R/R) Non-Hodgkin Lymphoma (NHL): Responses Observed In All Mantle Cell Lymphoma (MCL) Patients

New treatment options are needed for patients (pts) with R/R NHL, particularly in MCL where there are no curative options. Dysregulation of the anti-apoptotic protein Bcl-2 is a hallmark of NHL pathogenesis and contributes to chemotherapy resistance. ABT-199 is a selective, potent, orally bioavailable small molecule Bcl-2 inhibitor that is a promising agent for the treatment of pts with NHL.

The primary objectives of this phase I, dose-escalation study were to evaluate the safety and pharmacokinetics (PK), and to determine a maximum tolerated dose (MTD) and recommended phase 2 dose (RP2D) of ABT-199. Secondary objectives were to assess the efficacy of ABT-199 and to explore biomarkers for response. Adult pts requiring therapy, with ECOG performance status ≤1 and adequate marrow function (ANC ≥1.0 x 10⁹/L, Plt ≥50 x 10⁹/L) received ABT-199 on Week 1 Day -7 (W1D-7), followed by continuous, once-daily dosing from W1D1 until progressive disease or unacceptable toxicity. A 2 to 3 week lead-in period with stepwise escalation starting with lower doses to final cohort doses of 200, 300, 400, 600, and 900 mg was implemented. Evaluations include adverse events (AE; NCI-CTCAE-V4), PK parameters and disease responses (IWG 2007 criteria).

As of July 4, 2013, 32 pts were enrolled, 11 (34%) with follicular (FL), 8 (25%) with MCL, 8 (25%) with diffuse large B-cell (DLBCL), 1 (3%) with marginal zone (MZL), 3 (9%) with Waldenström macroglobulinemia (WM), and 1 (3%) multiple myeloma (MM). The median age was 68 (range 35-85), 63% were male with a median of 3.5 prior therapies (range 1-7), and the median time on study was 6.0 months (range 0.5-15.0). 44% of the pts had bulky disease ≥5 cm, including ≥10 cm in 16%. 22 pts have discontinued (D/C) drug: 18 due to progressive disease, 2 due to AEs, and 2 who proceeded to stem cell transplant in ongoing response. The most common AEs of any grade (G) occurring in ≥20% of pts were nausea (41%), diarrhea (31%), vomiting (22%), fatigue (22%), and upper respiratory tract infection (22%). G 3/4 AEs occurring in >3 pts were anemia (15%), neutropenia (13%), and thrombocytopenia (13%). G 3/4 thrombocytopenia was not dose-dependent or dose-limiting. Two of 10 pts in cohort 5 experienced a DLT (G3 febrile neutropenia and G4 neutropenia) at the target dose of 600 mg. G3 laboratory tumor lysis syndrome was seen after the initial dose in 1 pt with bulky MCL (elevations in phosphate and potassium only) and 1 pt with DLBCL (elevations in phosphate and uric acid only). After a single dose with food, ABT-199 had T_max and T_1/2 of approximately 8 and 15 hours, respectively. Food increased ABT-199 bioavailability by 3-4 fold. Preliminary efficacy data are summarized in the table.

ABT-199 showed anti-tumor activity as monotherapy for several NHL subtypes, with an overall response rate of 53% in this R/R population. Anti-tumor activity was seen in all MCL and WM pts treated across the range of ABT-199 cohort doses, and responses in DLBCL and FL pts were observed at doses ≥600 mg. Dose escalation is continuing to determine the MTD and RP2D. Biomarker studies are also underway in various NHL subtypes to explore a potential correlation with response.

Seymour:Genentech: Consultancy, Membership on an entity’s Board of Directors or advisory committees. Gerecitano:AbbVie: Research Funding; Genentech: Research Funding. Kahl:AbbVie, Inc.: Research Funding; Genentech: Consultancy, Research Funding. Wierda:AbbVie, Inc.: Research Funding; Genentech: Consultancy, Research Funding, Speakers Bureau. Anderson:Genentech: Research Funding; AbbVie, Inc.: Research Funding; Walter and Eliza Hall Institute of Medical Research: Employee, which recieves commercial income related to ABT-199, Employee, which recieves commercial income related to ABT-199 Other. Rudersdorf:AbbVie, Inc.: Employment, Stock Other. Gressick:AbbVie, Inc: Employment, Stock Other. Montalvo:AbbVie, Inc.: Employment, Stock Other. Yang:AbbVie, Inc.: Employment, Stock Other. Busman:AbbVie, Inc.: Employment, Stock Other. Dunbar:AbbVie, Inc.: Employment, Stock Other. Cerri:AbbVie, Inc.: Employment, Stock Other. Enschede:AbbVie, Inc.: Employment, Stock Other. Humerickhouse:AbbVie, Inc.: Employment, Stock Other. Roberts:AbbVie, Inc.: Research Funding; Genentech: Research Funding; Walter and Eliza Hall Institute of Medical Research: Employee, recieves commercial income related to ABT-199, Employee, recieves commercial income related to ABT-199 Other, Employment.