An Open‐Label, Multicenter, Phase <scp>II</scp> Study of Bexarotene in Patients with Adult T‐Cell Leukemia/Lymphoma

A multicenter, open-label, historically controlled, 2-arm phase II study was conducted to evaluate the safety, efficacy, and pharmacokinetics of bexarotene in Japanese patients with adult T-cell lymphoma/leukemia (ATL). The study enrolled patients with indolent ATL and skin lesions and patients with aggressive ATL who had skin relapse after achieving remission following ≥ 1 regimen of systemic chemotherapy. Patients received oral bexarotene at an initial dose of 100 mg/m² (15 patients) or 300 mg/m² (17 patients) once daily for 24 weeks. The 100 mg/m² group included 14 patients with indolent ATL and 1 with aggressive ATL. The 300 mg/m² group included 14 patients with indolent ATL and 3 with aggressive ATL. Of 12 patients in the 100 mg/m² group, 6 patients achieved complete response (CR) or partial response (PR) as the best overall response (50.0%; 95% confidence interval (CI), 25.4%-74.6%). Of 17 patients in the 300 mg/m² group, 12 patients achieved CR or PR (70.6%; 95% CI, 46.9%-86.7%) as estimated with the modified Severity Weighted Assessment Tool (mSWAT). Drug-related adverse events (AEs) occurred in 15 patients (100%) in the 100 mg/m² group and 16 of 17 patients (94.1%) in the 300 mg/m² group. The most common AEs were hypothyroidism (75.1%) and hypertriglyceridemia (53.1%). This is the first report to evaluate the safety and efficacy of bexarotene in ATL focused on skin lesions. In both groups, the response rate exceeded the threshold defined for the study. Bexarotene might be effective in improving skin lesions in ATL of any type with good tolerability. Trial Registration: This study was registered with the Japan Registry of Clinical Trials (jRCT2080224172).