Unfavorable impact of decreased muscle quality on the efficacy of immunotherapy for advanced non‐small cell lung cancer

BACKGROUND: Quantitative skeletal muscle mass loss has the potential to predict the therapeutic effects of immune checkpoint inhibitors. This study aimed to assess the impact of muscular quality on the abovementioned outcomes. METHODS: This study retrospectively reviewed the medical records of patients with advanced non‐small cell lung cancer (NSCLC) who had received PD‐1/PD‐L1 inhibitor monotherapy between March 2016 and February 2018. High muscle quality was stipulated as a skeletal muscle density ≥41 and ≥33 Hounsfield units in patients with a body mass index (BMI) <25 kg/m(2) and ≥25 kg/m(2), respectively, as assessed using lumbar computed tomography images. High muscle quantity was stipulated as a lumbar skeletal muscle index ≥41 cm(2)/m(2) in women, ≥43 cm(2)/m(2) in men with a BMI <25 kg/m(2), and ≥53 cm(2)/m(2) in men with a BMI ≥25 kg/m(2). We evaluated the associations of these muscular parameters with the overall response rate (ORR), progression‐free survival (PFS), and overall survival (OS). RESULTS: Out of 156 patients, 80 (51.3%) and 47 (30.1%) showed low muscle quality and quantity, respectively. Patients with high muscle quality showed higher ORR (35.0 vs. 15.8 %, p<0.05) and longer PFS durations (median, 4.5 vs. 2.0 months, p<0.05) than those with low muscle quality. There were no noted differences in the ORR or PFS between patients with high and those with low muscle quantities. On the contrary, regardless of muscle quality and quantity, there were no differences in OS between patients with high and those with low muscle status. CONCLUSIONS: Lumbar skeletal muscle quality has the potential to predict the therapeutic effect of anti‐programed cell death 1/programed cell death ligand 1 inhibitor monotherapy in patients with advanced NSCLC.