All-Oral Combo Shows Early Efficacy in R/R MM

The all-oral combination of selinexor plus pomalidomide and low-dose dexamethasone may be an effective treatment option for patients with relapsed or refractory multiple myeloma (MM), according to data from patients in the phase Ib/II STOMP and XPORT-MM-028 studies.

Researchers led by Darrell White, MD, of Queen Elizabeth II Health Sciences Centre and Dalhousie University in Halifax, Canada, analyzed data from 28 patients treated with selinexor 60 mg or 40 mg once a week with pomalidomide 4 mg once daily and dexamethasone 40 mg weekly (SPd).

The results were presented as a poster at the 2023 American Society of Clinical Oncology (ASCO) Annual Meeting.

The median duration of exposure to the 40 mg SPd (SPd-40) combination was 28 weeks, and to the 60 mg SPd (SPd-60) combination, 22 weeks.

Patients treated with the higher dose had higher overall response rates. For SPd-60 the overall response rate was 65% compared with 50% for SPd-40. Very good partial response or better was seen for 30% of patients treated with SPd-60 and 25% of patients treated with SPd-40.

However, with a median follow-up of one year, the median progression-free survival (PFS) was 9.5 months for SPd-60 compared with not reached for SPd-40. According to the researchers, this numerically longer PFS suggests, “that clinical benefit is optimized at the lower 40 mg dose”.  Among those patients treated with an anti-CD38 monoclonal antibody the median PFS was 8.9 months for both dosages.

Twenty-seven patients responded. The median time to response was 1.0 month with a median duration of response of 21.8 months.

There was one case of grade-3 or higher febrile neutropenia in each cohort. No high-grade hemorrhages occurred. The most common nonhematologic treatment-emergent adverse events were fatigue (43% vs 75%), nausea (32% vs 70%), and diarrhea (25% vs 35%) for the SPd-40 and SPD-60 cohorts, respectively.

Reference

White D, Shiller G, Madan S, et al. Efficacy and safety of 40 mg vs 60 mg once weekly selinexor in combination with pomalidomide and dexamethasone in relapsed and/or refractory multiple myeloma (RRMM). Abstract #e2006. Presented at the 2023 American Society of Clinical Oncology Annual Meeting; June 2-6, 2023; Chicago, Illinois.