Unrelated immunodeficiency states may impact outcomes and immune checkpoint molecule expression in patients with mycosis fungoides: A clinicopathologic case-control study.

BACKGROUND: Immunodeficiency (ID) correlates with worse outcomes and decreased immune checkpoint molecule expression in melanoma. The impact of ID in mycosis fungoides (MF) is unknown.

OBJECTIVE: Our goal was to evaluate the impact of ID in MF.

METHODS: We conducted a case-control study of 17 patients with MF and ID versus age-, stage-, and race-matched controls as a subset of a comparative analysis of 23 patients with MF with ID (prior lymphoma, recent/current pregnancy, HIV, hypogammaglobulinemia, and prior chemotherapy) versus without ID. Programmed cell death 1 (PD1), programmed death ligand 1 (PDL1), forkhead box p3, and interleukin 17 immunohistochemistry was performed on 12 patients with ID and 10 controls.

RESULTS: Patients with ID had more treatment failure (14 of 23 vs 5 of 17 [P = .028]), more treatment failure within 3 years of diagnosis (12 of 23 vs 4 of 17 [P = .050]), more angiocentrism (6 of 12 vs 0 of 10 [P = .005]), larger cells (1.92 ± 0.51 out of 3 vs 1.30 ± 0.48 out of 3 [P = .009]), more cases with at least 10% PD1 positivity (9 of 11 vs 4 of 10 [P = .031]) and at least 10% PDL1 positivity (7 of 12 vs 2 of 10 [P = .042]), and a higher average percentage of PD1+ cells (43.27 ± 40.22 vs 11.2 ± 13.62 [P = .028]). No differences in survival, forkhead box p3 expression, interleukin 17 expression, histologic depth, ulceration, granulomatous changes, or syringotropism were seen.

LIMITATIONS: This was a small single-center study with heterogeneous immunodeficiencies.

CONCLUSION: ID correlated with worse outcomes and increased PD1 and PDL1 expression in MF. Patients with MF and ID may be candidates for immune checkpoint inhibitor therapy, pending further investigation.