Bortezomib, Vorinostat, and Dexamethasone Combination Therapy in Relapsed Myeloma: Results of the Phase 2 MUK four Trial.

INTRODUCTION: Outcomes continue to improve in relapsed myeloma as more effective treatment options emerge. We report a multicenter single-arm phase 2 trial evaluating toxicity and efficacy of the histone deacetylase (HDAC) inhibitor vorinostat in combination with bortezomib and dexamethasone. PATIENTS AND METHODS: Sixteen patients who had received a median of 1 prior treatment line received bortezomib subcutaneously 1.3 mg/m2 days 1, 4, 8, and 11; dexamethasone 20 mg orally days 1-2, 4-5, 8-9, and 11-12; vorinostat 400 mg orally days 1-4, 8-11, and 15-18 of a 21-day cycle. After receipt of a minimum of 3 cycles of therapy, participants received maintenance vorinostat (400 mg days 1-4 and 15-18 of a 28-day cycle). RESULTS: Overall response was 81.3%: complete response occurred in 4 of 16, very good partial response in 2 of 16, and partial response 7 of 16. Clinical benefit response rate was 100%; median progression-free survival was 11.9 months. A total of 75% patients experienced a dose reduction or stopped treatment as a result of intolerability. CONCLUSION: Although toxicity and dose reductions were observed, this study demonstrates that the combination of vorinostat, bortezomib, and dexamethasone is effective in relapsed myeloma with good response rates, suggesting there is an ongoing rationale for further optimization of HDAC inhibitor-based combinations in the treatment of myeloma to improve tolerability and enhance efficacy.

Bendamustine, thalidomide and dexamethasone combination therapy for relapsed/refractory myeloma patients: results of the MUKone randomized dose selection trial.

There is a significant unmet need in effective therapy for relapsed myeloma patients once they become refractory to bortezomib and lenalidomide. While data from the front line setting suggest bendamustine is superior to melphalan, there is no information defining optimal bendamustine dose in multiply-treated patients. We report a multi-centre randomized two-stage phase 2 trial simultaneously assessing deliverability and activity of two doses of bendamustine (60 mg/m2 vs. 100 mg/m2) days 1 and 8, thalidomide (100 mg) days 1-21 and low dose dexamethasone (20 mg) days 1, 8, 15 and 22 of a 28-d cycle. Ninety-four relapsing patients were treated on trial, with a median three prior treatment lines. A pre-planned interim deliverability and activity assessment led to closure of the 100 mg/m2 arm due to excess cytopenias, and led to amendment of entry criteria for cytopenias. Non-haematological toxicities including thromboembolism and neurotoxicity were infrequent. In the 60 mg/m2 arm, treatment was deliverable in 61.1% subjects and the partial response rate was 46.3% in the study eligible population, with 7.5 months progression-free survival. This study demonstrates bendamustine at 60 mg/m2 twice per month with thalidomide and dexamethasone is deliverable for repeated cycles in heavily pre-treated myeloma patients and has substantial clinical activity.