Prognostic impact of thyroid dysfunctions on progression-free survival in patients with metastatic melanoma treated with anti-PD-1 antibodies

This study aimed to assess the prognostic value of thyroid dysfunctions in metastatic melanoma patients on anti-programmed death-1 (anti-PD-1). A total of 110 stage IV or inoperable stage III melanoma patients treated with anti-PD-1 alone or in association with anti-CTLA-4 (T-lymphocyte antigen-4) antibody from January 2015 to December 2017 at our institution were enrolled in this retrospective study. Median follow-up was 32.8 months. Transitory thyroid dysfunctions and permanent thyroid dysfunctions were distinguished. The main criterion was progression-free survival. Secondary criteria were best response and overall survival. Survival curves were compared with log-rank tests and a cox proportional hazard ratio model was used to adjust patients and melanoma characteristics. Thirty-eight (35%) thyroid dysfunctions were observed during the follow-up, including 25 transitory thyroid dysfunctions (23%) and 13 permanent thyroid dysfunctions (12%). Progression-free survival was longer in patients with thyroid dysfunction (18.1 months) than in patients without thyroid dysfunction (3.9 months, P = 0.0085). In multivariate analysis, thyroid dysfunctions were not an independent predictive factor for progression-free survival. Patients with thyroid dysfunction had a longer overall survival (P = 0.0021), and thyroid dysfunctions were associated with a lower mortality risk (hazard ratio = 0.40; P = 0.005). Best response was positively associated with thyroid dysfunctions (P = 0.048). Thyroid dysfunctions induced by anti-PD-1 were not an independent predictive factor for progression-free survival in metastatic melanoma patients but seemed associated with a better response and increased overall survival.