Multiple Myeloma Monotherapy Shows Strong Overall Response Rate

A drug granted accelerated approval in November 2015 for the treatment of multiple myeloma may provide significant hope for patients who did not respond to prior therapy.

Daratumumab (Darzalex), was approved as a single agent for patients who previously received at least 3 lines of therapy, including a proteasome inhibitor (PI) and an immunomodulatory agent, or in patients who are double-refractory to a PI and an immunomodulatory agent. Darzalex was the first monoclonal antibody approved for multiple myeloma, after it was previously granted priority review and breakthrough therapy designation by the FDA.

"The responses we saw in clinical trials that led to rapid approval were striking, especially considering that these patients received a median of five prior lines of therapy," said lead author Sagar Lonial, MD, chief medical officer at Winship Cancer Institute of Emory University. "It appears the novel mechanism of action for daratumumab may play an important role in its single-agent activity among this group of advanced-stage multiple myeloma patients."

In harnessing the immune system to treat multiple myeloma, Darzalex showed an overall response rate of approximately 30% in patients resistant to other anti-myeloma therapies.

The multi-center, open-label study evaluated response rates in 106 patients with relapsed or refractory multiple myeloma. Patients achieved an objective response rate of nearly 30%, with a median response duration of 7.4 months.

After 12 months, overall survival among patients in the trial was 64.8%. Additionally, at a subsequent cutoff the median overall survival was 17.5 months.

The drug was well tolerated, with the most common adverse events being fatigue, experienced by 40% of patients, and anemia, reported in 33% of patients. There were no drug-related adverse events that led to treatment discontinuation.

The recommended dose and schedule for daratumumab is 16 mg/kg once per week for 8 weeks, then once bi-weekly for 16 weeks, then once every 4 weeks until disease progression.

"This represents the first single agent activity we have for a monoclonal antibody in treating multiple myeloma. The future hope for daratumumab is in our ability to bring this active agent to earlier lines of therapy and combine it with drugs where you may get synergy," Dr. Lonial said.