A Phase I Study of Vorinostat, Lenalidomide, and Dexamethasone In Patients with Relapsed or Relapsed and Refractory Multiple Myeloma: Excellent Tolerability and Promising Activity In a Heavily Pretreated Population

Although novel treatment combinations for multiple myeloma (MM) have improved outcomes, the disease remains incurable and new drug combinations are urgently needed. Vorinostat is an oral histone deacetylase inhibitor approved in the United States for treatment of patients (pts) with advanced cutaneous T-cell lymphoma who failed prior therapies. Vorinostat alters gene expression and protein activity, promoting MM cell death through multiple pathways, and has been shown in preclinical studies to synergistically enhance the anti-MM activity of bortezomib and immunomodulatory drugs, including lenalidomide, with or without dexamethasone.

The primary objective of this Phase I study was to determine the maximum tolerated dose (MTD) of vorinostat plus lenalidomide and dexamethasone in pts with relapsed or relapsed and refractory MM. Secondary objectives included overall safety, tolerability, response rate, duration of response, and time to progression (TTP).

Pts in this Phase I multicenter open-label study were sequentially enrolled into 1 of 5 escalating doses of the combination regimen using a standard 3 + 3 design for ≤8 cycles. Pts who tolerated treatment and experienced clinical benefit were eligible for enrollment in an extension phase. Toxicity was evaluated using the National Cancer Institute Common Terminology Criteria (version 3.0). Response was assessed using the modified European Group for Blood and Marrow Transplantation criteria and International Myeloma Working Group Uniform Criteria. Safety and efficacy data were analyzed using summary statistics, except for TTP, which was estimated by the Kaplan-Meier method.

As of July 15, 2010, 31 pts were treated and evaluable for toxicity; 4 pts remain on study. Most pts had received prior thalidomide (n=22; 71%), bortezomib (n=20; 65%), or lenalidomide (n=14; 45%), with a median of 4 prior therapies (range, 1–10). The patient population contained both high-risk and low-risk pts, based on cytogenetic and/or fluorescence in situ hybridization analyses. Most adverse events (AEs) were mild or moderate in severity. The most common grade ≥3 treatment-related AEs, experienced by 19 (61%) pts, were neutropenia (26%), thrombocytopenia (16%), diarrhea (13%), anemia (10%), and fatigue (10%); 8 pts discontinued due to toxicity. One dose-limiting toxicity (grade 3 diarrhea lasting >48 h) was observed at the maximum assessed dose (level 5), but MTD was not reached (Table) and there were no treatment-related deaths. Among 30 pts evaluable for response, the median TTP was 32 weeks (5 mo), and 4 pts remain on study as of the data cutoff date; 26 of 30 pts (87%) have achieved at least stable disease (SD). Best single responses included 2 complete responses, 3 very good partial responses (VGPR), 11 partial responses (PR), and 5 minimal responses (MR), with 5 pts achieving SD and 4 developing progressive disease, resulting in an overall response rate (ORR; PR or better) of 53%. Of 13 evaluable pts who had previously received lenalidomide, a best single response of SD or better was observed in 9 (69%; 2 VGPR, 3 PR, 1 MR, 3 SD), resulting in a 38% ORR. Notably, SD or better (2 PR, 1 MR, 3 SD) was observed in 60% of 10 evaluable pts who were relapsed, refractory, or intolerant to previous lenalidomide-containing regimens.

Preliminary data from this Phase I study suggest that vorinostat plus lenalidomide and dexamethasone is a convenient and generally well-tolerated regimen with promising activity for relapsed or relapsed and refractory MM. The MTD for this combination was not reached. Importantly, responses were observed in pts who had received prior lenalidomide, bortezomib, and thalidomide. Further evaluation of this regimen is planned in future trials.

Richardson:Celgene: Membership on an entity's Board of Directors or advisory committees; Millenium: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees; Johnson & Johnson: Membership on an entity's Board of Directors or advisory committees. Off Label Use: Vorinostat, Lenalidomide, and Dexamethasone for treatment in Multiple Myeloma. Weber:Novartis-unpaid consultant: Consultancy; Merck- unpaid consultant: Consultancy; Celgene- none for at least 2 years: Honoraria; Millenium-none for 2 years: Honoraria; Celgene, Millenium, Merck: Research Funding. Mitsiades:Millennium: Consultancy, Honoraria; Novartis Pharmaceuticals: Consultancy, Honoraria; Bristol-Myers Squibb: Consultancy, Honoraria; Merck & Co.: Consultancy, Honoraria; Kosan Pharmaceuticals: Consultancy, Honoraria; Pharmion: Consultancy, Honoraria; Centrocor: Consultancy, Honoraria; PharmaMar: Patents & Royalties; OSI Pharmaceuticals: Research Funding; Amgen Pharmaceuticals: Research Funding; AVEO Pharma: Research Funding; EMD Serono: Research Funding; Sunesis: Research Funding; Gloucester Pharmaceuticals: Research Funding; Genzyme: Research Funding. Dimopoulos:MSD: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees. Harousseau:Janssen-Cilag: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Houp:Merck Research Laboratories: Employment. Graef:Merck Research Laboratories: Employment. Gause:Merck Research Laboratories: Employment. Byrne:Celgene Corporation: Employment, Equity Ownership. Anderson:Millennium Pharmaceuticals: Consultancy; Celgene: Consultancy; Novartis: Consultancy; Onyx: Consultancy; Merck: Consultancy; BMS: Consultancy; Acetylon: Equity Ownership, Membership on an entity's Board of Directors or advisory committees. Siegel:Celgene and Millennium: Advisory Board, Speakers Bureau; Merck: Advisory Board.