The Significance of Longitudinal Psoas Muscle Loss in Predicting the Maintenance Efficacy of Durvalumab Treatment Following Concurrent Chemoradiotherapy in Patients with Non-Small Cell Lung Cancer: A Retrospective Study

Sarcopenia assessed at a single time point is associated with the efficacy of immunotherapy, and we hypothesized that longitudinal changes in muscle mass may also be important. This retrospective study included patients with non-small cell lung cancer (NSCLC) who received durvalumab treatment after concurrent chemoradiotherapy (CCRT) between January 2017 and April 2023. Muscle loss and sarcopenia were assessed based on the lumbar skeletal muscle area. Patients with a decrease in muscle area of 10% or more during CCRT were categorized into the muscle loss group, while those with a decrease of less than 10% were categorized into the muscle maintenance group. We evaluated the relationship between muscle changes during CCRT and the efficacy of durvalumab treatment. Among the 98 patients, the muscle maintenance group had a significantly longer PFS of durvalumab treatment compared to the muscle loss group (29.2 months [95% confidence interval (CI): 17.2-not reached] versus 11.3 months [95% CI: 7.6-22.3]; <i>p</i> = 0.008). The multivariable analysis confirmed that muscle change was a significant predictor of a superior PFS (HR: 0.47 [95% CI: 0.25-0.90]; the <i>p</i>-value was less than 0.05). In contrast, the OS between the groups did not differ significantly (not reached [95% CI: 21.8 months-not reached] and 36.6 months [95% CI: 26.9-not reached]; <i>p</i> = 0.49). Longitudinal muscle changes during CCRT are a predictor of durvalumab's efficacy in patients with NSCLC after CCRT.