Pharmacist Medication Insights: Melphalan Flufenamide for Multiple Myeloma

In March, the FDA approved melphalan flufenamide (Pepaxto; melflufen) for use in combination with dexamethasone to treat adult patients with relapsed or refractory multiple myeloma, who have received at least 4 prior lines of therapy and whose disease is refractory to at least 1 proteasome inhibitor, 1 immunomodulatory agent, and 1 CD38-directed monoclonal antibody.

The approval was based on data from the phase 2 HORIZON study, which evaluated intravenous melphalan flufenamide in combination with dexamethasone. The multi-center, single arm study enrolled heavily pre-treated patients with a poor prognosis, which included 157 patients with relapsed/refractory multiple myeloma who had received 2 or more prior lines of therapy, were exposed to an immunomodulatory drug and a proteasome inhibitor, and were refractory to pomalidomide (Pomalyst) and/or daratumumab (Darzalex).

Participants had triple-class refractory disease and/or EMD and/or high-risk cytogenetic features. To be eligible for enrollment, patients had to have had an ECOG performance status of 0 to 2. Of those enrolled, 97 patients had triple-class refractory disease and had received at least 4 previous lines of treatment.

Study participants were given 40 mg of melphalan flufenamide on day 1 plus 40 mg of dexamethasone on days 1, 8, and 15. However, patients who were 75 years of age or older were given 20 mg of dexamethasone instead. Treatment was administered in 28-day cycles until either progressive disease or unacceptable toxicity.

The overall response rate (ORR) for patients in this group with refractory multiple myeloma was 23.7% and the median duration of response was 4.2 months. The results showed that melphalan flufenamide in combination with dexamethasone demonstrated activity in a subset of patients with extra medullary disease (41%), which is associated with a poor prognosis, according to the study authors.