Daratumumab shows promise in immune thrombocytopenia

Treatment with daratumumab yields rapid and durable therapeutic effects and shows acceptable safety profile in adults with immune thrombocytopenia, according to a phase 2 trial.

A total of 63 patients (median age 33 years, 73 percent female) with a platelet count of <30 × 10⁹ platelets/L (median 9 × 10⁹ platelets/L) participated in the trial. These patients received intravenous daratumumab treatment at 16 mg/kg once weekly for 8 consecutive weeks.

At baseline, the median platelet count was 9 × 10⁹ platelets/L. Bleeding severity, according to the WHO bleeding scale, was grade 0 in 35 patients, grade 1 in 22 patients, and grade 2 in six patients. All patients completed the 8-week treatment course and the 16-week follow-up.

The primary endpoint of two or more consecutive platelet counts of ≥50 × 10⁹ platelets/L within 8 weeks occurred in 83 percent of patients. Notably, 73 percent of patients met the endpoint within the first week.

Overall response rate at week 8 was 78 percent, including a complete response in 51 percent. By week 24, 60 percent had an overall response.

The proportion of patients with bleeding symptoms (WHO grade 1–4) decreased from 44 percent at baseline to 10 percent at week 8. The rate of infusion-related reactions was 32 percent, most of which occurred during the initial administration. A total of 32 percent of patients contracted infections, including upper respiratory tract infections in 24 percent.