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Isatuximab Under Study in Daratumumab-Refractory Multiple Myeloma

By: Anna Nowogrodzki
Posted: Tuesday, August 31, 2021

Monotherapy with the monoclonal antibody isatuximab yielded a disease control rate of 38% in daratumumab-refractory patients with multiple myeloma, according to a recent phase II study. Joseph Mikhael, MD, of the Translational Genomics Research Institute, Phoenix, and colleagues published their results in a letter in Blood Cancer Journal.

“To our knowledge, this was the first prospective study evaluating the ability of anti-CD38 monoclonal antibody monotherapy to overcome the refractoriness of patients to a different anti-CD38 monoclonal antibody,” the authors wrote.

The study included 32 patients with daratumumab-refractory multiple myeloma across 19 sites in the United States and Europe. All patients had received their last daratumumab treatment at least 6 weeks before the first study treatment. Patients received isatuximab at 20 mg/kg every week for 4 weeks and then every other week.

Of the 32 patients, 1 achieved molecular response, and 17 (53%) had stable disease as their best overall response. The longest duration of stable disease was 18.5 months. No patient had an objective response. The disease control rate was 38%. The authors defined the disease control rate as achieving at least molecular response or stable disease after at least 8 weeks.

The researchers observed better disease control rates in patients with at least 6 months between the last daratumumab dose and the first isatuximab dose. The disease control rates were 26% for patients who received their last daratumumab dose less than 6 months prior, 58% for those who received their last dose at least 6 months prior, and 60% for those who received their last dose at least 12 months prior. The authors recommend further study to understand whether isatuximab after daratumumab, or vice versa, is more optimal and the ideal timing of treatments.

Disclosure: The study authors’ disclosures may be found at

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