Bortezomib, Bendamustine, and Rituximab in Patients with Relapsed or Refractory Follicular Lymphoma: Encouraging Activity in the Phase 2 VERTICAL Study.

Abstract 933

Follicular lymphoma (FL) is an incurable, indolent B-cell non-Hodgkin lymphoma. Although survival has improved with the introduction of rituximab (Rituxan^®, R), relapse is inevitable and new therapies are needed. Bortezomib (Velcade^®, V) plus rituximab is active in relapsed or refractory (rel/ref) FL (de Vos et al, ASH 2006). Bendamustine (Treanda^®, B) plus R has also shown activity in rel/ref FL (Robinson et al, J Clin Oncol 2008), and V has been safely combined with B in patients (pts) with advanced multiple myeloma (Fenk et al, Leuk Lymph 2007). The single-arm, multicenter, phase 2 VERTICAL study was conducted to determine the efficacy and safety of V and R in combination with B (VBR) in pts with rel/ref FL. Here we report preliminary phase 2 efficacy and safety findings from pts treated with VBR at doses determined in the dose-escalation phase of this study (Matous et al, ASCO 2009). Pts with rel/ref FL who had received ≥4 prior doses of R (no prior V or B), and had ≥1 measurable tumor mass, no active central nervous system lymphoma, Karnofsky Performance Status (KPS) ≥50%, adequate hematologic, renal, and hepatic function, and no grade ≥2 peripheral neuropathy (PN) were eligible. Pts could receive up to five 35-d cycles of V 1.6 mg/m² (d 1, 8, 15, 22), B 90 mg/m² (d 1, 2), and R 375 mg/m² (d 1, 8, 15, 22, cycle 1; d 1, cycles 2–5). Response was assessed by the investigator using International Working Group criteria (Cheson et al, J Clin Oncol 2007). Adverse events (AEs) were graded using the CTCAE v3.0, and by laboratory assessment of hematologic toxicity. Sixty-three pts received VBR; median age was 58 years, 63% were male and 25% had KPS ≤80%. At diagnosis, 47% had grade 1, 26% grade 2, and 8% grade 3 histology, and 18% unknown histology; 35% had high-risk Follicular Lymphoma International Prognostic Index score. Pts had received a median of 2 prior therapies (range 1–11), and 39% were refractory to their last prior rituximab-containing therapy. The median time from diagnosis was 48 months. As of data cut-off (14 Aug 2009), pts had received a median of 3 cycles (range 1–5); 29 pts remain on therapy and 10 have completed treatment. In the 49 pts with at least one post baseline response assessment, to date, the overall best response rate was 84%; 23 (47%) pts achieved a complete response (CR) and 18 (37%) a partial response (PR). VBR was generally well tolerated, with manageable toxicities. The most common treatment-related AEs were primarily grade 1 and 2 and included nausea (79%; 3% grade 3), fatigue (65%; 10% grade 3), diarrhea (57%; 3% grade 3), and vomiting (44%; 5% grade 3). Other non-hematologic grade 3/4 AEs that occurred in more than one pt included syncope (n=2; 3%) and PN (see below). Grade 3/4 neutropenia, thrombocytopenia, and anemia were seen in 25%, 6%, and 3% of pts, respectively. Treatment-related serious AEs were reported in 17 (27%) pts, including 3 (5%) with febrile neutropenia and 1 (2%) with grade 3 herpes zoster who did not receive antiviral prophylaxis and discontinued therapy. Of the 17 (27%) pts with treatment-related PN, only 4 (6%) had grade 3 (2 discontinued therapy; no grade 4); PN has resolved in 5 (29%) pts to date. There was one on-study death (cardiac arrest) that was considered treatment-related. Additional follow-up is required to assess long-term outcomes, including progression-free and overall survival. VBR is active in this heavily pre-treated, high-risk population, with high CR rates, and was generally well tolerated. Efficacy and safety data will be updated and reported at ASH.