FDA Approval Summary: Mogamulizumab-kpkc for Mycosis Fungoides and Sézary Syndrome.

The FDA-approved mogamulizumab-kpkc, a CC chemokine receptor type 4 (CCR4)-directed mAb, in August 2018 for treatment of adult patients with relapsed or refractory mycosis fungoides or Sézary syndrome after at least one prior systemic therapy. Regular approval was based on a randomized, open-label trial that randomized 372 such patients, with a median of 3 prior systemic therapies, to either mogamulizumab-kpkc or vorinostat. Investigator-assessed progression-free survival (PFS) was statistically significantly longer in the mogamulizumab-kpkc arm, which had an estimated median PFS of 7.6 months [95% confidence interval (CI), 5.6-10.2] compared with 3.1 months (95% CI, 2.8-4.0) in the vorinostat arm (HR = 0.53; 95% CI, 0.41-0.69). The confirmed overall response rate was 28% and 5%, respectively (P < 0.001), based on global composite response criteria. Adverse reactions occurring in at least 20% of mogamulizumab-kpkc recipients included rash, infusion-related reactions, fatigue, diarrhea, musculoskeletal pain, and upper respiratory tract infection. Serious adverse reactions occurred in 36% of patients, most often from infection. The prescribing information includes warnings for dermatologic toxicity, infusion reactions, infections, autoimmune complications, and complications of allogeneic hematopoietic stem cell transplantation, including severe and steroid-refractory graft-versus-host disease.See related commentary by Larocca et al., p. 7272.