Our study suggests that HPD is more common with PD-1/PD-L1 inhibitors compared with chemotherapy in pretreated patients with NSCLC and is also associated with high metastatic burden and poor prognosis in patients treated with PD-1/PD-L1 inhibitors. Additional studies are needed to determine the molecular mechanisms involved in HPD.

Inhibition of immune checkpoints using anti-programmed cell death-1 (PD-1) or anti cytotoxic-T-lymphocyte-associated antigen 4 (CTLA-4) monoclonal antibodies has revolutionized the management of patients with advanced-stage melanoma and is among the most promising treatment approaches for many other cancers. Use of CTLA-4 and PD-1 inhibitors, either as single agents, or in combination, has been approved by the US FDA for the treatment of metastatic melanoma. Treatment with these novel immunotherapies results in a unique and distinct spectrum of adverse events, which are mostly related to activation of the immune system and are, therefore, an unwanted consequence of their mechanisms of action. Adverse effects of CTLA-4 and/or PD-1 inhibition are most commonly observed in the skin, gastrointestinal tract, liver and endocrine systems and include pruritus, rash, nausea, diarrhoea and thyroid disorders. In this Review, the authors describe the adverse event profile of checkpoint inhibitors targeting CTLA-4 and PD-1, used both as monotherapies and in combination and aim to provide some general guidelines, based upon the mechanisms of action of these therapies and on the management of these immune-related adverse events.

IMPORTANCE Vitiligo is an autoimmune skin disorder that reacts against melanocytes. The association of vitiligo with tumor response in patients with melanoma who undergo immunotherapy has been reported but is still controversial. OBJECTIVE To prospectively evaluate the appearance of vitiligo in patients receiving pembrolizumab, a monoclonal antibody directed against the programmed death cell receptor. DESIGN, SETTING, AND PARTICIPANTS This prospective observational study was conducted from January 1, 2012, through September 24, 2013, in a single tertiary care hospital with a unit dedicated to patients with melanoma. Sixty-seven patients with metastatic melanoma who received pembrolizumab treatment in the context of a phase 1 study were included and screened for the emergence of vitiligo. Data were collected from January 1, 2012, to February 28, 2014, and analyzed from February through December 2014. MAIN OUTCOMES AND MEASURES Objective tumor response with regard to the occurrence of vitiligo in patients receiving pembrolizumab therapy. Correlation between vitiligo occurrence and overall survival was also estimated using the Kaplan-Meier product-limit method and compared with a log-rank test. To prevent guarantee-or lead-time bias, a landmark analysis approach after 12, 16, and 20 weeks of treatment was retained. RESULTS Of the 67 patients included in the study, 17 (25%) developed vitiligo during pembrolizumab treatment and 50 (75%) did not. An objective (complete or partial) response to treatment was associated with a higher occurrence of vitiligo (12 of 17 [71%] vs 14 of 50 [28%]; P = .002). The time to onset of vitiligo ranged from 52 to 453 (median, 126) days from the start of treatment. Of the 17 patients with vitiligo, 3 (18%) had a complete response, 9 (53%) had a partial response, 3 (18%) had stable disease, and 2 (12%) had progressive disease at the final follow-up. All the patients treated with pembrolizumab who developed vitiligo were alive at the time of analysis, with a median follow-up of 441 days. CONCLUSIONS AND RELEVANCE Vitiligo, a clinically visible immune-related adverse event could be associated with clinical benefit in the context of pembrolizumab treatment.