Estimating the clinical and economic impact of delaying recurrence in resectable gastric and gastroesophageal junction cancer in the United States.

295 Background: In the MATTERHORN trial, perioperative treatment with durvalumab + FLOT (D-FLOT) demonstrated a statistically significant and clinically meaningful improvement in event free survival compared to FLOT alone among patients with resectable gastric (GC) and gastroesophageal junction cancer (GEJC). This study aimed to quantify the direct (healthcare and terminal care spending) and indirect (productivity) cost offsets associated with delaying disease recurrence and predicting the number of events that may be averted with D-FLOT vs FLOT in a cohort of patients eligible for treatment. Methods: A 3 state semi Markov model was developed to predict the cumulative number of recurrences and deaths and the associated direct, indirect, and terminal care costs associated with recurrences over a 3-year and 5-year time horizon if patients were treated with D-FLOT versus FLOT. Number of eligible patients in the US was systematically derived by applying sequential criteria (stage, resection candidacy, FLOT eligibility) based on published epidemiologic data. Recurrence and mortality rates were based on published MATTERHORN data. Distributions with the lowest Bayesian Information Criterion (BIC) were used to project trial outcomes over the model horizon. Cost inputs were derived from published literature and Medicare fee schedule. Direct costs included post-recurrence drug acquisition and administration costs, disease monitoring costs, and healthcare resource utilization costs. Indirect costs included time away from work time for patients and caregivers. Terminal care costs included palliative and end-of-life care. Results: An estimated 2,832 patients in the US were eligible to receive perioperative FLOT or D-FLOT. Based on the model, a predicted 350 recurrences and 232 deaths may be averted within 3 years, extending to 453 recurrences and 398 deaths averted over 5 years. This translated to a predicted 354 life years saved at 3 years and 1,133 life years saved at 5 years, with corresponding productivity gains ranging from 452,643 to 280,574 patient work hours and 894,339 to 1,091,222 caregiver work hours over 3-5 years. Estimated cost offsets in direct, indirect, and terminal care costs totaled to $98.0 million, $61.6 million, and $5.8 million respectively, saved over the 3-year horizon, increasing to $133.8 million, $62.8 million, and $9.8 million respectively, saved over the 5-year time horizon. Conclusions: In addition to clinical benefit, delaying recurrence may be associated with economic and societal benefits through downstream cost offsets, increased patient productivity and reduced caregiver burden.