PANORAMA 2: Panobinostat Combined with Bortezomib and Dexamethasone in Patients with Relapsed and Bortezomib-Refractory Multiple Myeloma

There are limited treatment options for patients (pts) with multiple myeloma (MM) whose disease is refractory to bortezomib (BTZ) and are relapsed and/or refractory, intolerant or ineligible to receive an immunomodulatory (IMiD) drug. These pts have a poor prognosis with a response rate for subsequent BTZ-containing regimens of 20% and median event-free survival of 5 months (Kumar S, et al. Leukemia. 2011). Panobinostat (PAN) is an oral pan-deacetylase inhibitor (pan-DACi) that has low nanomolar activity against all class I, II, and IV histone deacetylase enzymes, including those implicated as potential targets in MM. PAN synergizes with BTZ to inhibit both the aggresome and proteasome pathways in preclinical studies. Phase 1 results with PAN + BTZ demonstrated clinical responses in pts with BTZ-refractory disease. PANORAMA 2 expands upon these results and evaluates whether PAN can recapture responses in BTZ-refractory MM pts.

Pts with relapsed and BTZ-refractory MM (≥2 prior lines of therapy including an IMiD and who had progressed on or within 60 days of the last BTZ-based therapy) were treated in this single-arm, phase 2 study with PAN + BTZ + dexamethasone (Dex) in 2 phases. Treatment phase 1 (TP1) consisted of 8 three-week cycles of oral PAN (20 mg) + intravenous BTZ (1.3 mg/m²) + oral Dex (20 mg). Pts demonstrating clinical benefit (≥stable disease [SD]) could proceed to treatment phase 2 (TP2), which consisted of 6-week cycles until disease progression. The primary endpoint was overall response rate (≥partial response [PR]), as defined by the European Group of Blood and Marrow Transplantation (EBMT) 1998 criteria, in TP1. Secondary efficacy endpoints included minimal response (MR), time to response (TTR), duration of response (DOR), progression-free survival (PFS), time to progression (TTP), and overall survival (OS). Secondary safety endpoints included safety and tolerability.

Fifty-five pts with BTZ-refractory MM were enrolled (median age, 61 years [range, 41–88 years]). Pts were heavily pretreated with a median of 4 prior regimens (range, 2–11), and a median of 2 prior BTZ-containing regimens (range, 1–6). All pts (100%) were previously treated with BTZ, Dex, and at least 1 IMiD (lenalidomide [98%], thalidomide [69%]). The majority of pts received prior autologous stem cell transplant (64%). Forty-five pts (82%) received Dex with their last BTZ-containing regimen. In the most recent prior line of therapy, 27 pts (49%) had BTZ. As of the February 20, 2012, cutoff, all pts had completed TP1 or stopped treatment, and 7 of the 18 pts who entered TP2 were ongoing. The overall response rate was 35% (1 near complete response [nCR] and 18 PR or better, with 3 pts [5%] achieving a very good partial response [VGPR; Table]). An additional 10 pts achieved MR, for a clinical benefit rate of 53%. The median duration of exposure was 4.6 months (range, < 1–14.8 months). The median PFS and TTP were 4.9 months. The PFS rates for pts whose disease progressed on BTZ (n = 39) and within 60 days of BTZ (n = 16) were 4.2 and 7.6 months, respectively. In pts who achieved a response, the mean TTR was 1.7 months (range, 0.1–3.9), and the median DOR was 6.0 months. With a median follow-up time of 8.1 months, the median OS has not been reached. Common adverse events (AEs) of any grade regardless of study drug relationship included diarrhea (71%), fatigue (69%), thrombocytopenia (65%), nausea (60%), anemia (47%), dyspnea (44%), decreased appetite (42%), and peripheral edema (40%). Common grade 3/4 AEs regardless of study drug relationship included thrombocytopenia (64%), fatigue (20%), diarrhea (20%), anemia (15%), pneumonia (15%), and neutropenia (15%). Only 1 pt (2%) experienced grade 3 peripheral neuropathy.

PAN, when combined with BTZ and Dex can recapture responses in heavily pretreated, BTZ- and Dex-refractory MM pts. The regimen was tolerable with manageable toxicities, with 33% of pts on therapy for > 8 cycles. The combination of PAN, BTZ and Dex is therefore an important potential therapeutic option for relapsed and refractory MM pts, including those with BTZ, Dex, and IMiD resistance.

Richardson:Novartis: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees; Millennium: Membership on an entity's Board of Directors or advisory committees; Johnson & Johnson: Membership on an entity's Board of Directors or advisory committees. Alsina:Millenium: Consultancy, Research Funding. Weber:Novartis: Research Funding. Lonial:Millennium: Consultancy; Celgene: Consultancy; Novartis: Consultancy; Bristol-Myers Squibb: Consultancy; Onyx: Consultancy; Merck: Consultancy. Gasparetto:Millenium: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Celgene: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Mukhopadhyay:Novartis: Employment. Ondovik:Novartis: Employment, Equity Ownership. Khan:Novartis: Employment. Paley:Novartis: Employment, Equity Ownership. Schlossman:Celgene: Membership on an entity's Board of Directors or advisory committees.