AT MHM 2015
CHICAGO (FRONTLINE MEDICAL NEWS) – Subcutaneous and intravenous bortezomib performed comparably well in patients with newly diagnosed multiple myeloma, according to a review of 372 cases.
The findings, which showed a trend toward higher cumulative dosage and improved outcomes with the subcutaneous route, are consistent with those from a phase III study (Lancet Oncology. 2011;12[5]:431-40) of patients with relapsed or refractory multiple myeloma, Dr. Robert M. Rifkin reported in a poster at the American Society of Hematology Meeting on Hematologic Malignancies.
Median treatment duration in 248 patients who received subcutaneous bortezomib and 124 who received intravenous bortezomib was similar at 4.4 and 4.1 months, respectively. Dose reductions were required in the first 16 weeks in 10% and 13% of patients in the groups, respectively, and median time to dose reduction was 49 days in both groups, said Dr. Rifkin of the Rocky Mountain Cancer Center, McKesson Specialty Health/US Oncology Network, Denver.
Median relative dose intensities were the same in the two groups, but the subcutaneous group had a higher median cumulative dose (25.8 mg/m2 vs. 22.9 mg/m2). When dichotomized by median cumulative dose, those in the subcutaneous group were more likely to have received the higher dose (52% vs. 48%), he said, noting that a higher cumulative dose was associated with longer improved response and progression-free survival (PFS) at 12 weeks. The odds ratio for improved objective response with greater vs. less than 24.7 mg/m2 was 2.20 and the hazard ratio for PFS was 0.34.
Two-year overall survival was similar at 81% and 78%; 2-year PFS was 75% and 70% in the groups, respectively.
Among 204 patients who were evaluable with respect to response, the complete response/very good partial response rates at a median of 19.1 and 20.8 months were16% and 22% in the subcutaneous and intravenous groups, respectively, Dr. Rifkin said.
Adverse events included neuropathy in 34% and 38%, thrombocytopenia in 13% and 10%, neutropenia in 10% and 5%, and anemia in 25% and 24% of patients in the groups, respectively.
The previously observed noninferiority of subcutaneous vs. intravenous bortezomib has the potential to affect treatment outcomes in the clinical setting, but there was a lack of comparative effectiveness data on the two treatment approaches as initial therapy in newly diagnosed multiple myeloma patients, he noted.
The current findings, based on adults treated between Jan. 1 and Dec. 31, 2012, within the McKesson Specialty Health/US Oncology Network, demonstrate a trend toward higher cumulative dose in the subcutaneous group, which was associated with improved response and PFS. The findings support extended therapy for higher cumulative dosage and better treatment outcomes, he concluded.
Dr. Rifkin is a board or advisory committee member for Celgene, Millenium: The Takeda Oncology Company, and Onyx.
