A phase II trial suggests that anti-CD38 antibody daratumumab is effective as a standalone therapy for heavily treated multiple myeloma.

In a group of 106 patients whose disease worsened after at least three prior treatments, nearly one in three responded to daratumumab, and disease progression was delayed by 3.7 months, on average.

The estimated one-year overall survival rate was 65%.

An estimated 26,850 Americans will be diagnosed with multiple myeloma in 2015.

Despite recent advances in treatment, the disease remains incurable, as all patients
ultimately become resistant to therapy.

Less than half of patients survive five years after diagnosis.

“The efficacy we’re seeing is quite impressive for a clinical trial of refractory multiple myeloma, given that many patients had already undergone five or more types of treatment,” said lead study author Saad Zafar Usmani, MD, a haematologist at Levine Cancer Institute/Carolinas Healthcare System in Charlotte.

“Our hope is that daratumumab will help fill the unmet clinical need of patients who have exhausted available treatment approaches.”

Daratumumab is a first-in-class antibody targeting CD38, a protein found in high levels on the surface of myeloma cells, as well as in lower levels of the surface of several other kinds of immune cells.

This is the largest study to show impressive activity of a monoclonal antibody as a standalone therapy for treatment-resistant multiple myeloma.

The researchers are reporting results on 106 patients treated on the study.

In these patients, the cancer progressed despite having received an average of five prior therapies, including proteasome inhibitors, immunomodulatory drugs, and chemotherapy.

After a median follow-up period of 9.4 months, 29.2% of patients responded to daratumumab, with three experiencing complete remission.

Responses were durable, lasting 7.4 months on average.

Overall, the median time to disease progression was 3.7 months, and the estimated overall survival rate at one year was 65%.

The major side effect of daratumumab was infusion reaction, which typically occurred early in the course of the treatment and was generally well managed.

In fact, fewer than 5% of patients discontinued treatment due to an infusion reaction.

Other side effects included fatigue, low blood counts, back pain, and cough.

Ongoing phase III trials are exploring daratumumab in combination with various existing treatments to further solidify the role of this antibody across all stages of the disease.

In May 2013, the FDA granted breakthrough therapy designation to daratumumab for the treatment of multiple myeloma in patients who have received at least three prior lines of therapy.

This designation helps accelerate the development and review process for drugs to treat serious or life-threatening illnesses.

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Source: ASCO