Elranatamab shows efficacy in relapsed, refractory multiple myeloma
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Subcutaneous elranatamab demonstrated efficacy and a manageable safety profile in patients with relapsed or refractory multiple myeloma, according to data presented at the virtual ASCO Annual Meeting.
Nizar J. Bahlis, MD, from the University of Calgary, reported updates for subcutaneous dosing of elranatamab (PF-0686313, Pfizer), a B-cell maturation antigen (BCMA)-CD3 bispecific antibody, in relapsed/refractory multiple myeloma from the ongoing phase 1 MagnetisMM-1 study at the virtual ASCO Annual Meeting.
Patients received subcutaneous elranatamab at 80, 130, 215, 360, 600 and 1000 g/kg each week. Researchers used modified toxicity probability interval method for escalation, with monitoring for dose-limiting toxicity (DLT) to the end of first cycle. They reported treatment-emergent adverse events (TEAEs), the occurrence of cytokine release syndrome (CRS) and response as well as performed pharmacokinetics, cytokine profiling and T-cell immunophenotyping.
As of August 2020, 30 patients had received elranatamab at 80 (n = 6), 130 (n = 4), 215 (n = 4), 360 (n = 4), 600 (n = 6) or 1000 (n = 6) g/kg subcutaneous weekly. Patients had a median of 8 prior treatments (87% had triple refractory disease, 97% had prior anti-CD38 therapy and 23% had prior BCMA-directed antibody drug conjugate or CAR T-cell therapy).
The most common TEAEs were lymphopenia (n = 24; 20% grade 3 and 60% grade 4), CRS (n = 22; none were above grade 2), anemia (n = 17; 43% grade 3 and 3% grade 4), injection site reaction (n = 16; none were above grade 2), thrombocytopenia (n = 16; 23% grade 3 and 17% grade 4) and neutropenia (n = 12; 17% grade 3 and 17% grade 4). Exposure increased with dose and cytokine increases occurred with the first dose; researchers observed increased T-cell proliferation in peripheral blood.
Investigators observed responses beginning at the dose of 250 g/kg, according to Bahlis.
“At doses higher or equal to 150 [g/kg], the confirmed overall response rate by the International Myeloma Working Group criteria is 70%. Of those, 30% are complete remission or stringent complete remission. At the recommended phase 2 dose of 1,000 [g/kg], the overall response rate is 83.3%,” Bahlis said in the presentation.
Bahlis also noted the median time to response was 22 days.
“These results clearly support the further development of elranatamab both as monotherapy or in combination with other anti-myeloma agents,” he said.
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Bahlis NJ, et al. Abstract 8006. Presented at: ASCO Annual Meeting; June 4-8, 2021 (virtual meeting).
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