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 one year (± three 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/1.73m2) modified this association. Results 36 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% 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 patient s not treated with ICIs, which was not affected by baseline eGFR.