Retrospective Study of Clinical Outcomes and Toxicity Profile in Patients Treated with Immune Checkpoint Inhibitors

Abstract

Introduction Immune checkpoint inhibitors (ICIs) are rapidly being utilized as treatment option either alone or in combination with chemotherapy in most of the solid tumors. Objectives Our single-center retrospective study aimed to present our experience with the effectiveness and safety of these agents in Indian set of patients with various advanced solid tumors. Material and Methods Twenty-five adult patients with stage IV solid tumors of varying sites treated with ICIs at Aditya Birla Memorial Hospital, Pune, Maharashtra, India, between October 2017 and September 2020 were included in the study. Overall survival (OS), progression-free survival (PFS), overall response rate (ORR), disease control rate (DCR), and toxicity profiles were evaluated. All statistical calculations were performed using IBM SPSS version 25. Results Total of 25 patients (median age 61) was evaluated. Histological evaluation revealed adenocarcinoma (48%), squamous cell carcinoma (40%), and one each (4%) of others. Eastern Cooperative Oncology Group performance status score was I in 16 (64%) and II in 9 (36%) patients. Average of 10 cycles ICIs were received by each patient. Majority were males with 11 (44%) having some comorbidities. Lung (48%) was the most common primary followed by head and neck cancers (32%). Most (76%) were treated with nivolumab, followed by pembrolizumab (20%) while only one patient was given atezolizumab. Median follow-up was 18 months. Median OS was 24 months (95% confidence interval [CI]: 9–NA) and 2-year OS rate in the study was 38.4% (95% CI: 18.8–78.3), while median PFS was 9 months (95% CI: 6–NA) and 1-year PFS rate was 22.3% (95% CI: 9.7–51.2). One patient (4%) had complete response, 6 (24%) had partial response while 12 (48%) had stable disease response at first follow-up. Mean and median time to progression were 5.7 and 9 months, respectively. ORR was 28% (95% CI: 12.07–49.4) while the DCR was 76% (95% CI: 54.87–90.64). PS II patients were associated with significantly poor median OS and PFS. There was no significant difference in survival with respect to age, gender, site, histology, and comorbidities; however, 4/25 patients had undergone biomarker assessment and were associated with a trend toward better median PFS (8 vs. 11 months, hazard ratio 0.53, 95% CI: 0.12–2.34, p = 0.38). Two of 25 patients developed autoimmune conditions namely ophthalmoplegia and hypothyroidism each. Fatigue (36%) and nausea (12%) were the most common toxicities. Conclusion Real-world data from our study depicts our own experience with ICIs to suggest that these agents are well-tolerated and equally effective in Indian set of patients with advanced metastatic solid tumors. ICIs could be safely used even in patients with PS II and biomarker assessment in adjunction needs to be encouraged wherever feasible for better patient selection, prognostication, and clinical outcomes.