Phase I/II Study of Bortezomib in Combination with Liposomal Doxorubicin and Melphalan in Relapsed or Refractory Multiple Myeloma.

Phase I/II studies using either liposomal doxorubicin (D) or oral melphalan (M) in combination with the proteasome inhibitor bortezomib (V) have found favorable efficacy and tolerance in patients with relapsed and refractory MM. Since these drugs have different mechanisms of action and toxicity profiles, we initiated a phase I/II study to examine the safety and efficacy of combining all three agents (DMV) in relapsed or refractory myeloma.

Study Aims: Starting at 25–50% of the doses used in the two drug combination studies, the objective of this dose escalation study was to evaluate the safety/tolerability of DMV until the maximum tolerated dose (MTD) and dose limiting toxicity (DLT) could be identified. Efficacy was also evaluated.

Methods: Patients with relapsed/refractory MM and progressive disease requiring treatment were enrolled in the study. Dose level 1 consisted of D 10 mg/m2 and M 5 mg/m2 given IV on day 1 with V given by IV push on days 1, 4, 8, and 11. Cycles were repeated every 28 days up to a maximum of 6 cycles. Dose levels of D, M, V (mg/m2) in the subsequent three cohorts were (10, 10, 0.7), (20, 10, 0.7), and (20, 10, 1.0) respectively. Once the MTD has been identified, an additional 17 patients will be enrolled at this dose level in the phase II portion of the study.

Results: 5 patients (2 males, median age 65, range 33–79) have been enrolled in the study thus far. The myeloma subtypes include 2 IgG, 1 IgA, and 2 with light chains only. In this heavily pretreated population (range 2–7 prior therapies), 4 patients received prior autologous stem cell transplantation, 2 had a prior nonmyeloablative allogenic transplant, 4 prior VAD, 1 prior bortezomib, 2 prior oral melphalan, 3 prior thalidomide, 2 prior CC-5013, and 2 prior spinal radiation.

The first dose cohort has been completed without any DLT. One patient had 3 days of Grade 3 neutropenia. All other toxicities were Grade 1–2 including asthenia, vomiting, thrombocytopenia, and headache. Of note, a patient with baseline Grade 2 peripheral neuropathy and on hemodialysis remained stable. A patient with Grade 2 chronic graft versus host disease also remained stable.

Four patients have been enrolled at dose level one. One patient, who had progressive disease after an autologous and a nonmyeloablative allogenic transplant as well as CC5013, had a near CR (IFE+) after the second cycle of DMV. Two patients have had stable disease. One had disease progression after one cycle and subsequently died. The patient on dose level two is too early to evaluate.

Conclusion: Thus far, DMV appears to be well tolerated and no DLT has been observed even in elderly patients with significant comorbidities. The finding of a near CR and SD at only dose level 1 is encouraging particularly since the patients were significantly pretreated. Dose escalation continues to determine the MTD.