A longitudinal retrospective case series of the real-world toxicities encountered among cancer patients receiving anti-PD-L1 checkpoint inhibitor immunotherapy.

e15117 Background: Immunotherapy with anti-PD-L1 immune checkpoint inhibitors is currently a major component of systemic therapy in advanced solid tumors. Their toxicity profile has been well established through clinical trials, however the rapid integration of these agents in routine cancer care did not allow the identification of the complete spectrum of unusual or rare immune-related adverse events. Methods: We retrospectively reviewed the records of 142 patients, who received nivolumab or pembrolizumab between June 2015 and January 2018. Eligible patients received at least 2 cycles (2-45, median 8) and only grade 3-5 or mild toxicities that required intervention were recorded. Routine clinical and laboratory exams, including TSH, were performed every 1-2 cycles, along with imaging, when clinically indicated. Results: A total of 127 patient-records were eligible for documentation of treatment-related toxicity. Underlying disease was lung cancer (69%), melanoma (16%), renal (16%) and urothelial cancer (6%). Skin toxicity was exhibited in 10% of patients (N = 13). A case of persistent, generalized vitiligo appeared after 15 cycles of therapy, but did not require therapy modification. 2 out of 11 patients with gastrointestinal toxicity, developed grade 3-4 colitis that resolved with conservative treatment. Among 5 patients (3.9%) with pulmonary toxicity, only one with pneumonitis grade 3 required permanent cessation of therapy. Thyroid dysfunction was the most commonly recorded toxicity; hypothyroidism in 16.4% (N = 21) and hyperthyroidism in 11,8% (N = 15) of patients. All cases were successfully managed with medical intervention and did not delay immunotherapy. Further endocrine toxicities included a case of diabetes and two cases of adrenal insufficiency. Other rare entities were a case of interstitial nephritis grade 3 confirmed with renal biopsy and a grade 3 hepatitis. Conclusions: Real-world experience with anti-PD-L1 immune checkpoint inhibitors revealed a wide spectrum of immune-related adverse events. Special caution is required for the prompt identification of mild toxicity before it escalates to life-threatening situations.