A recent in vivo exploratory analysis of selected mitochondrial markers, from the skeletal muscle of female C57BL/6 mice with melanoma (B16F10 cell line) or breast cancer (EO771 cell line) 141, suggested that exposure to both isotype control (IgG2a) and anti-PD-1 antibodies can modify the response to exercise of skeletal muscle mitochondria in a tumor-type dependent mode. Here, PDCD1 is linked to breast cancer.