Improved overall survival in patients developing endocrine toxicity during treatment with nivolumab for advanced non-small cell lung cancer in a prospective study.

Purpose: Immune checkpoint inhibitors (ICPIs) disrupting PD-1/PD-L1 axis have revolutionized the management of advanced non-small cell lung cancer (NSCLC). Some studies identified the development of endocrine toxicity as predictor of better survival in cancer patients treated with ICPIs. The aim of study was to evaluate survival and new onset of immune-related endocrine adverse events (irAEs) in patients treated with nivolumab for advanced NSCLC.

Methods: In a prospective study, 73 patients with previously treated advanced NSCLC received nivolumab in monotherapy. Blood samples were collected at each cycle to monitor thyroid autoimmunity, thyroid, adrenal and somatotroph axes, while thyroid morphology was evaluated by ultrasonography.

Results: An impaired thyroid function was recorded in 23.4% of patients (n = 15). Eight patients developed asymptomatic transient thyrotoxicosis (ATT) evolving to hypothyroidism in 50% of cases. In addition, seven patients developed overt hypothyroidism without ATT and with negative autoantibodies. Patients who developed hypothyroidism proved to have better overall survival (OS) as compared with non-developers at both univariate (p = 0.021) and multivariate analyses (p = 0.023). The survival curve of patients with reduced IGF-I at baseline, or displaying its reduction during the follow-up, showed significantly reduced median survival compared to patients with normal/high IGF-I levels (p = 0.031).

Conclusions: Thyroid function abnormalities are the major irAEs in patients treated with nivolumab, and hypothyroidism onset is associated with prolonged survival. Our findings indicate that the development of hypothyroidism is a positive predictive biomarker of nivolumab antitumor efficacy in patients with NSCLC. Low IGF-I levels could represent a negative prognostic factor during nivolumab therapy.