Mogamulizumab efficacy on the skin compartment of cutaneous T‐cell lymphomas based on longitudinal analysis

Summary Cutaneous T‐cell lymphoma is staged by the degree of skin, lymph node, viscera and blood involvement. Skin response is a determinant of treatment decisions. Mogamulizumab, an anti‐CC chemokine receptor 4 antibody, is approved for mycosis fungoides and Sézary syndrome after ≥1 systemic therapy. Longitudinal changes in modified Severity‐Weighted Assessment Tool (mSWAT) score, and cluster of differentiation (CD)4 + CD7 − /CD26 − cell subsets during mogamulizumab treatment were investigated as an exploratory post‐hoc analysis. While chronological differences in mSWAT scores were not interpreted by a linear mixed model (LMM) due to a statistically significant interaction term, significant differences based on responses in CD7 − (−690.5/μL; 95% confidence interval [CI], −1195 to −186.2; p = 0.0076) and CD26 − (−1029/μL; 95% CI, −1705 to −353.7; p = 0.0030) cell counts were identified. Actual values of mSWAT scores decreased for responders at Week (W) 12 and 24 from baseline (BL) (mean ± standard error: BL: 97.57 ± 6.52; W12: 52.34 ± 6.16; W24: 34.89 ± 4.93) following a rapid decrease of CD7 − cells in blood at W4 (BL: 2809 ± 650.3/μL; W4: 204.4 ± 50.76/μL; W12: 101.9 ± 28.81/μL; W24: 152.8 ± 54.98/μL). Monitoring both blood and skin improvements is important for effective mogamulizumab treatment in patients with advanced stage disease.