The U.S. Food and Drug Administration (FDA) has approved the use of the monoclonal antibody daratumumab -(Darzalex) in combination with pomalidomide (Pomalyst) and dexamethasone for the treatment of patients with multiple myeloma who have received at least two prior therapies including lenalidomide (Revlimid) and a proteasome inhibitor.
The approval was based on data from the phase I (MMY1001, EQUULEUS) study of daratumumab in combination with pomalidomide and dexamethasone in relapsed or refractory multiple myeloma. Daratumumab targets the CD38 protein.
About the Study
One arm of the phase I EQUULEUS open-label study included 103 patients with multiple myeloma who had received prior treatment with a proteasome inhibitor and an immunomodulatory agent. Patients in the study received 16 mg/kg of daratumumab in combination with pomalidomide and dexamethasone.
The overall response rate in the study was 59% (95% confidence interval [CI] = 49.1%–68.8%), with very good partial response achieved in 28% of patients. Complete response was achieved in 6% of patients and stringent complete response was achieved in 8% of patients. The median time to response was 1 month (range = 0.9–2.8 months). The median duration of response was 13.6 months (range = 0.9+ to 14.6+ months).
Safety and Toxicity
The most frequent adverse reactions (> 20%) in the study were infusion reactions (50%), diarrhea (38%), nausea (30%), vomiting (21%), fatigue (50%), pyrexia (25%), upper respiratory tract infection (50%), muscle spasms (26%), cough (43%), and dyspnea (33%). The overall incidence of serious adverse reactions was 49%.
Serious adverse reactions (grade 3/4) reported in ≥ 5% patients included pneumonia (7%). The most common treatment-emergent hematology laboratory abnormalities were lymphopenia (94%), neutropenia (95%), thrombocytopenia (75%), and anemia (57%). The most common grade 3/4 treatment-emergent hematology laboratory abnormalities were neutropenia (82%), lymphopenia (71%), anemia (30%), and thrombocytopenia (20%).
Daratumumab was approved previously for use in combination with lenalidomide and dexamethasone or bortezomib and dexamethasone, in people who have received at least one prior medicine to treat multiple myeloma; and alone in people who have received at least three prior medicines to treat multiple myeloma, including a proteasome inhibitor and an immunomodulatory agent, or did not respond to a proteasome inhibitor and an immunomodulatory agent. ■