A Phase II Study of Pegylated Liposomal Doxorubicin, Bortezomib and Dexamethasone (DVD) for Patients with Previously Untreated Multiple Myeloma (MM).

Abstract 4936

Despite recent advances in the treatment of MM, the disease remains incurable and many of the most effective, newer combination therapies are accompanied by significant side effects that have a major negative impact on the patient's quality of life. Pegylated liposomal doxorubicin (PLD) and bortezomib have shown anti-MM efficacy in the laboratory and for the treatment of previously treated MM patients, leading to FDA approval for patients who have failed one prior therapy. Using our severe combined immunodeficiency-hu murine models of human MM, we have previously demonstrated that lower doses of PLD administered daily are more effective and better tolerated than higher amounts given weekly. Moreover, the combination of bortezomib and dexamethasone has been shown to be effective for previously untreated MM patients. Prior studies by our group have shown that combining chemotherapy including PLD with bortezomib administered at 1.0 mg/m² on days 1, 4, 8, and 11 of a 28-day cycle rather than the standard 1.3 mg/m² on the same days of a 21-day schedule is effective for MM patients with relapsed or refractory disease and associated with a reduction in the incidence and severity of peripheral neuropathy. Thus, we conducted a single-arm multi-center phase II study for previously untreated MM patients to evaluate the combination of intravenously administered dexamethasone, bortezomib and PLD (DVD). The treatment consisted of intravenous administration of 40 mg dexamethasone followed by 1.0 mg/m² bortezomib and finally 5.0 mg/m² PLD on days 1, 4, 8, and 11 of a 28-day cycle. Patients were treated to a maximum response plus two additional cycles or completed a maximum of eight cycles of therapy without disease progression. To date, 22 (of 35 planned) patients have been enrolled with a median age of 64 years (range, 42-79 years). The majority of those on study (68 %) were diagnosed with International Staging System II or III MM. Four patients are too early to assess for response. To date, among the 18 evaluable patients, 16 (89%) have shown objective responses to the DVD regimen, including 2 complete responses (11%), 8 partial responses (44%) and 6 minimal responses (33%). The other 2 patients (11%) had stable disease, with one of these subjects showing a continuing reduction in M-protein after 2 cycles of therapy to date. Thus, disease control was achieved in all patients. To date, no patient has shown progressive disease after 2+ - 12+ months of follow-up. Six patients experienced grade 3 adverse events and one patient with a prior history of pulmonary interstitial fibrosis developed a grade 4 toxicity (shortness of breath). Grade 3 adverse events in three of the six patients were judged not to be related to the study treatment. The most common grade 3 adverse event was reversible neutropenia (n=2). To date, only 2 patients (9%) have developed peripheral neuropathy (grade 1). Notably, there have been no cases of stomatitis or hand-foot syndrome. Thus, these results suggest that the DVD regimen using a modified schedule and doses of the combination of intravenous dexamethasone, bortezomib and PLD is a well tolerated treatment that produces high response rates for previously untreated patients with multiple myeloma.