The European Commission has granted conditional approval to daratumumab as monotherapy in adult patients with relapsed or refractory multiple myeloma (MM) who progressed after treatment with a proteasome inhibitor and an immunomodulatory drug (IMiD). Czech investigators evaluated outcomes in heavily pretreated patients in a real-world setting to confirm the benefits demonstrated in clinical trials of daratumumab.
The study examined relapsed/refractory MM patients from the Registry of Monoclonal Gammopathies (RMG) of the Czech Myeloma Group. Patients had received ≥2 prior lines of therapy, which included both a proteasome inhibitor and IMiD. In the pivotal daratumumab monotherapy trials, patients had received treatment by physician’s choice or daratumumab monotherapy (16 mg/kg). From the RMG database, investigators identified 972 treatment lines (3rd to ≥6th line) in 463 patients, between 2006 and 2013.
The median observed progression-free survival (PFS) for daratumumab and physician’s choice of treatment was 5.8 months and 4.0 months, and median overall survival (OS) on multivariate analysis was 20.1 months and 11.9 months, respectively. Older age, high beta-2 microglobulin levels, thrombocytopenia incidence, and double/triple/quadruple-refractory status were all independent, statistically significant risk factors for increased mortality. The adjusted hazard ratios favoring daratumumab were 0.33 for PFS and 0.79 for OS. These benefits were observed despite daratumumab-treated patients being older and exposed to more drugs (including carfilzomib and pomalidomide), having a higher incidence of thrombocytopenia, and being more likely to be triple-refractory.
The authors concluded that treatment with daratumumab led to longer PFS than treatment by physician’s choice. They further noted that the adjusted comparisons between trial data and historical cohorts can provide useful insights to clinicians and reimbursement decision makers on the relative treatment efficacies, in the absence of head-to-head comparison studies for daratumumab monotherapy.
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