Elranatamab Granted Breakthrough Therapy Designation by FDA for Relapsed/Refractory Myeloma

The FDA has granted breakthrough therapy designation to elranatamab as a treatment for patients with relapsed/refractory multiple myeloma, according to a press release from Pfizer.

The designation for the B-cell maturation agent (BCMA), CD3-targeted bispecific antibody was supported by findings from 6-month follow data from cohort A (n = 123) of the phase 2 MagnetisMM-3 study (NCT04649359). This trial was designed to assess safety and efficacy of elranatamab monotherapy in the aforementioned patient population. In addition to demonstrating a manageable safety profile, patients achieved an overall response rate (ORR) of 61.0% at a median follow-up of 6.8 months. Of these patients, 90.4% had a probability of maintaining a response at 6 months or longer. In terms of safety, frequent treatment-emergent adverse effects included cytokine release syndrome (57.9%), most of which were grade 1 (43.2%) or grade 2 (14.2%).

The study’s updated findings are due to be presented at the 2022 American Society of Hematology Annual Meeting and Exposition.

“The FDA’s breakthrough designation recognizes the potential of elranatamab as an innovative medicine for [patients] with multiple myeloma whose disease has relapsed or is refractory to existing treatments, which at present leaves very few avenues for staving off this currently incurable cancer,” Chris Boshoff, MD, PhD, chief development officer of Oncology and Rare Disease at Pfizer Global Product Development, said in the press release.

Patients included in the study were treated with subcutaneous elranatamab at a dose of 76 mg every week along with a 2-step-up priming dose that was given during the first week. The trial’s primary end point was objective response rate, with secondary outcomes including objective response rate in those with extramedullary disease, duration of response, complete response rate, progression-free survival, time to response, minimal residual disease negativity rate, and overall survival.

Patients were able to enroll on the trial if they had measurable disease and were refractory to at least one immunomodulatory agent, a proteosome inhibitor, an anti-CD38 antibody, and an anti-myeloma regimen. Those in cohort A were not able to have previously received a BCMA–directed therapy, while those in cohort B could. Additional enrollment criteria included having an ECOG performance status of 0 to 2, resolving any acute effects from prior therapies to baseline severity, and not being pregnant with a willingness to use contraception.

Those with smoldering myeloma, active plasma cell leukemia, amyloidosis, or POEMS (Polyneuropathy, Organomegaly, Endocrinopathy, Monoclonal protein, and Skin changes) syndrome were not eligible to participate in the study. Additional exclusion criteria included undergoing stem cell transplantation 12 weeks before enrollment; having active hepatitis B or C virus, COVID-19, human immunodeficiency virus; having uncontrolled bacterial, fungal, or viral infections; or any other malignancy within 3 years of enrollment, excluding treated basal cell carcinoma or squamous cell skin cancer or carcinoma in situ. Treatment with a previous investigational drug within 30 days of the first study dose was also not allowed.

Reference

Pfizer’s elranatamab granted FDA breakthrough therapy designation for relapsed or refractory multiple myeloma. News release Pfizer. November 3, 2022. Accessed November 3, 2022. http://bit.ly/3h9I9YM