A study of the efficacy and toxicity outcomes of extended durvalumab dosing in patients with stage III unresectable non-small cell lung cancer (NSCLC) during the COVID-19 pandemic

BACKGROUND: Durvalumab following chemoradiation in unresectable stage III non-small cell lung cancer (NSCLC) has led to improved outcomes. The schedule of administration has been determined by pharmacokinetic studies. This study evaluates real-world efficacy and safety outcomes of extended dosing (ED) vs. standard dosing (SD) of durvalumab. METHODS: Stage III NSCLC patients treated at the Cancer center of Southeastern Ontario with consolidative durvalumab from March 2017-December 2020 were included. Patient characteristics and outcomes were evaluated through retrospective review. Comparisons were made using chi-square and t-tests. Kaplan-Meier curves were used to analyze overall survival (OS). RESULTS: A total of 35 patients were included; 15 (43%) switched to ED. Distant recurrence rates were higher in the ED group (53% vs. 20%, p = 0.07), with no differences in the sites of disease recurrence. A similar proportion of patients were alive in the ED vs. SD group (93% vs. 80%, p = 0.3), with no significant difference in OS. There were less grade 3 or greater immune-related adverse events in the ED group (0% vs. 20%). Treatment discontinuation occurred in 47% vs. 50% in the ED vs. SD groups, respectively, owing to toxicity in 20% of patients in the ED group vs. 40% in the SD group. CONCLUSIONS: Extended dosing has similar efficacy and toxicity to standard dosing; however, there was a higher rate of toxicity necessitating discontinuation in the SD group, which may have impacted the clinical decision-making to switch to ED. Our data is limited by a small sample size and should be further validated in larger cohorts.