Cyclophosphamide, bortezomib and dexamethasone induction for newly diagnosed multiple myeloma: High response rates in a phase II clinical trial

We have studied a three-drug combination with cyclophosphamide, bortezomib and dexamethasone (CyBorD) on a 28-day cycle in the treatment of newly diagnosed multiple myeloma (MM) patients to assess response and toxicity. The primary endpoint of response was evaluated after four cycles. Thirty-three newly diagnosed, symptomatic patients with MM received bortezomib 1.3 mg/m² intravenously on days 1, 4, 8 and 11, cyclophosphamide 300 mg/m² orally on days 1, 8, 15 and 22 and dexamethasone 40 mg orally on days 1-4, 9-12 and 17-20 on a 28-day cycle for four cycles. Responses were rapid with a mean 80% decline in the sentinel monoclonal protein at the end of two cycles. The overall intent to treat response rate (≥ partial response) was 88%, with 61% of very good partial response or better (≥ VGPR) and 39% of complete/near complete response (CR/nCR). For the 28 patients who completed all four cycles of therapy, the CR/nCR rate was 46% and VGPR rate was 71%. All patients undergoing stem cell harvest had a successful collection. Twenty-three patients underwent stem cell transplantation (SCT) and are evaluable through day 100 with CR/nCR documented in 70% and ≥ VGPR in 74%. In conclusion, CyBorD produces a rapid and profound response in patients with newly diagnosed MM with manageable toxicity.