Association of immune checkpoint inhibitors with muscle mass and density in patients with melanoma

BACKGROUND: The association between skeletal muscle wasting and immune checkpoint inhibitor (ICI) use for cancer and whether pre-treatment kidney function modifies this relationship is unknown. MATERIALS AND METHODS: Single center retrospective cohort study of patients with non-metastatic melanoma treated with or without ICIs, with a pre-treatment CT or PET-CT scan and follow-up scan within 1 year (±3 months). Paired t-tests examined the change in abdominal skeletal muscle index (SMI, cm2/height in meters) and psoas muscle density (PMD, Hounsfield units) at L3. Independent t-tests compared differences in the mean change between the ICI and non-ICI groups. Multivariable linear regression models assessed whether the change in SMI and PMD was different between groups and whether baseline estimated glomerular filtration rate (eGFR, mL/min/1.73 m2) modified this association. RESULTS: Thirty-six patients treated with ICIs and 41 not treated with ICIs met inclusion criteria. The non-ICI group was older (mean age ± SD = 67.0 ± 12.9 years) and more commonly male (78%) compared to the ICI group (58.9 ± 14.9 years; 50% male). The mean change in SMI was not significantly different between groups (P = 0.38). The mean change in PMD in the ICI group was -5.93 (95% confidence interval [CI] -9.58 to -2.28), which was significantly greater than the non-ICI group (-1.18, 95% CI -3.51 to 1.15), after adjusting for baseline variables (P = 0.002). Findings were not affected by baseline eGFR. CONCLUSION: Patients treated with ICIs had a significantly higher decline in PMD as compared to patients not treated with ICIs, which was not affected by baseline eGFR.