Time-to-Event Analyses in PANORAMA 2: A Phase 2 Study of Panobinostat, Bortezomib, and Dexamethasone in Patients With Relapsed and Bortezomib-Refractory Multiple Myeloma

Abstract Background Multiple myeloma (MM) remains an incurable disease, with a high unmet need for patients (pts) in the relapsed and refractory setting. The prognosis is especially worse for pts with MM refractory to both bortezomib (BTZ) and immunomodulatory drugs (IMiDs), who have a median progression-free survival (PFS) and median overall survival (OS) of 5 and 9 months, respectively (Kumar, Leukemia 2012). Panobinostat is an oral pan-deacetylase inhibitor (pan-DACi) that has low nanomolar activity against histone deacetylase enzymes that are implicated as potential targets in MM. In preclinical studies, panobinostat and BTZ synergistically inhibit both the aggresome and proteasome pathways. In an interim analysis of PANORAMA 2, panobinostat, in combination with BTZ and dexamethasone (Dex), demonstrated the ability to recapture responses in pts with relapsed and BTZ-refractory MM. At the time of the interim analysis, multiple pts were still receiving treatment, and median OS had not been reached. Here, we present an updated analysis of PANORAMA 2, including an evaluation of PFS and OS. Methods This multicenter, single-arm, phase 2 study enrolled pts with relapsed and BTZ-refractory MM (who had received ≥ 2 prior lines of therapy, including an IMiD, and had progressed on or within 60 days of the last BTZ-based therapy). Pts received oral panobinostat, intravenous BTZ, and oral Dex. The primary endpoint was overall response rate (defined as ≥ partial response [PR]) as defined by the modified European Group of Blood and Marrow Transplantation criteria. Secondary objectives included evaluation of minimal response (MR), time to response, duration of response, PFS, OS, and safety and tolerability of the combination. Results The median age of the 55 enrolled pts was 61 years (range, 41-88), and pts were heavily pretreated with a median of 4 prior regimens (range, 2-11) including a median of 2 prior BTZ-containing regimens (range, 1-6). All pts had received at least 1 IMiD, all were BTZ refractory, and nearly half (n = 27) had BTZ in their most recent prior line of therapy. Most pts (75%) were International Staging System stage 1 or 2, and 14 pts presented with high-risk cytogenetics (del[17p], t[4;14], or t[14;16]). All but 2 pts had discontinued from the study as of the December 4, 2012, data cutoff due to disease progression (n = 36), adverse events (n = 10), or withdrawal of consent (n = 5); 1 pt had died, and 1 pt started new therapy. One pt (2%) had a near complete response and 18 pts (33%) had a PR for an overall response rate of 35%, which met the study's primary objective of response rate > 10% (95% CI, 22-47; P < .0001). An additional 10 pts (18%) had an MR, for a clinical benefit rate of 53% (95% CI, 39-66). The median exposure was 4.6 months (range, < 1-24.1). The median PFS was 5.4 months (95% CI, 3.5-6.7). The median OS was 17.5 months (95% CI, 10.8-25.2). In a post hoc analysis, the 19 pts who achieved ≥ PR had a median PFS of 7.6 months (95% CI, 5.8-9.7) and a median OS of 25.2 months (95% CI, 17.5-25.2), while the 36 pts with < PR had a median PFS of 2.6 months (95% CI, 2.1-4.9) and a median OS of 9.9 months (95% CI, 5.4-17.4). Similarly, the 29 pts with ≥ MR had a median PFS of 6.9 months (95% CI, 4.9-8.6) and a median OS of 22.2 months (95% CI, 17.5-25.2), and the 26 pts with < MR had a median PFS of 2.1 months (95% CI, 1.4-3.0) and a median OS of 7.9 months (95% CI, 4.1-12.2). No new safety signals were observed. Common grade 3/4 adverse events regardless of study drug relationship included thrombocytopenia (64%), diarrhea (20%), fatigue (20%), anemia (15%), neutropenia (15%), and pneumonia (15%). Peripheral neuropathy was observed in 27% of pts overall, with only 1 (2%) grade 3/4 event. Conclusions The combination of panobinostat, BTZ, and Dex in heavily pretreated relapsed and BTZ-refractory pts demonstrated a median PFS of 5.4 months and a median OS of 17.5 months, which relates favorably to historical controls and other active combinations in this setting (eg, pomalidomide/Dex and carfilzomib/Dex). As expected, pts who achieved ≥ PR or ≥ MR appeared to have a longer median PFS and OS than pts who did not, which is supportive of a clinical benefit for this combination in this vulnerable population with otherwise limited treatment options. The large, randomized, phase 3 study, PANORAMA 1, will further define the role of panobinostat combined with BTZ and Dex in pts with relapsed and relapsed/refractory MM. Disclosures: Richardson: 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; Novartis: Membership on an entity’s Board of Directors or advisory committees. Schlossman:Celgene: Consultancy; Millennium: Consultancy. Alsina:Millennium: Membership on an entity’s Board of Directors or advisory committees, Research Funding. Weber:Novartis: Research Funding. Coutre:Novartis: Consultancy, Research Funding. Gasparetto:Millennium: Honoraria, Speakers Bureau. Mukhopadhyay:Novartis: Employment. Ondovik:Novartis: Employment, Equity Ownership. Khan:Novartis: Employment. Paley:Novartis: Employment, Stock options Other. Lonial:Sanofi: Consultancy; BMS: Consultancy; Novartis: Consultancy; Celgene: Consultancy; Millennium: Consultancy; Onyx: Consultancy.