On August 8, 2018, the US Food and Drug Administration (FDA) approved mogamulizumab-kpkc (Poteligeo, Kyowa Kirin, Inc.) for adult patients with relapsed or refractory mycosis fungoides (MF) or Sézary syndrome (SS) after at least one prior systemic therapy.

The approval of mogamulizumab-kpkc, a CC chemokine receptor type 4 (CCR4) directed monoclonal antibody, was based on a randomized, open-label, multicenter trial (Study 0761-010; NCT01728805) in patients with active MF or SS after at least one prior systemic therapy. Patients enrolled had a median of three prior therapies. The trial randomised 372 patients (44% with SS) to either mogamulizumab-kpkc or vorinostat.

Progression-free survival (PFS) was statistically significantly longer in the mogamulizumab-kpkc arm. The estimated median PFS was 7.6 months (95% CI: 5.6, 10.2) for those treated with mogamulizumab-kpkc compared with 3.1 months (95% CI: 2.8, 4.0) in the vorinostat arm (hazard ratio 0.53; 95% CI: 0.41, 0.69). The confirmed overall response rate was 28% and 5%, respectively (P < 0.001).

The most common adverse reactions (reported in ≥ 20%) were rash, infusion-related reactions, fatigue, diarrhoea, musculoskeletal pain, and upper respiratory tract infection. Serious adverse reactions occurred in 36% of patients, most often from infection (16% of all patients). The prescribing information includes warnings for dermatologic toxicity, infusion reactions, infections, autoimmune complications, and complications of allogeneic hematopoietic stem cell transplantation, including severe and refractory graft-versus-host disease.

The recommended mogamulizumab-kpkc dose is 1 mg/kg administered as an intravenous infusion over at least 60 minutes. Mogamulizumab-kpkc is administered on days 1, 8, 15, and 22 of the first 28-day cycle, then on days 1 and 15 of subsequent 28-day cycles until disease progression or unacceptable toxicity.

FDA granted this application priority review, breakthrough therapy designation, and orphan drug designation.