Ofatumumab monotherapy was active and well tolerated, with a low incidence of IgM flare, among patients with previously untreated or relapsed Waldenström macroglobulinemia, according to a study published in The Lancet Haematology.1

Because more effective and safer treatments, particular non-chemotherapeutics, are needed to improve outcomes for patients with Waldenström macroglobulinemia, researchers evaluated the clinical activity and safety of ofatumumab monotherapy among patients with relapsed Waldenström macroglobulinemia and among those with untreated disease.

For the multicenter, open-label, phase 2 trial (ClinicalTrials.gov Identifier: NCT00811733), researchers enrolled 37 patients to receive up to 3 cycles of weekly ofatumumab for 5 weeks. Patients with stable disease or a minor response after 16 weeks were eligible to then receive a redosing cycle of ofatumumab over 6 weeks. Patients responding to cycle 1 or the redosing cycle who developed disease progression within 36 months could receive cycle 2 of ofatumumab.

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Results showed that 51% (95% CI, 34.4-68.1) of the 37 patients achieved an overall response after cycle 1 and 59% (95% CI, 42.1-75.2) achieved an overall response after the redosing cycle, including 15 partial responses and 7 minor responses.

Among the 13 patients who received cycle 2 of ofatumumab, researchers found that 77% achieved a response.

Each patient experienced at least 1 adverse event and 43% had grade 3 to 4 adverse events. The most frequently reported grade 3 to 4 adverse events were infusion reactions, chest pain, hemolysis, and neutropenia.

Only 2 patients experienced an IgM flare, characterized by an initial upsurge in immunoglobulin M levels after treatment, but the impact of an IgM flare on clinical outcomes remains unclear.

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The findings suggest that ofatumumab monotherapy should be a novel non-chemotherapeutic strategy for patients with Waldenström macroglobulinemia, particularly those with high IgM concentrations.

Reference

  1. Furman RR, Eradat HA, DiRienzo CG, et al. Once-weekly ofatumumab in untreated or relapsed Waldenström’s macroglobulinaemia: an open-label, single-arm, phase 2 study. Lancet Haematol. 2016 Nov 30. doi: 10.1016/S2352-3026(16)30166-1 [Epub ahead of print]

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Hematologic Cancers