Aging is a major risk factor for melanoma. Older patients are likely to develop more aggressive disease and usually respond poorly to treatment. Kugel et al. analyzed biopsies from melanoma patients and compared these samples with a murine model of disease. Unexpectedly, melanoma was less likely to progress in older patients and mice given pembrolizumab (an antibody therapy targeting the immune checkpoint regulator PD-1). The tumor microenvironments of older individuals were found to have fewer regulatory T cells (Tregs) that were positive for the marker FOXP3. Pembrolizumab was more effective in younger mice in which Tregs had been depleted by an antibody targeting CD25, indicating the possibility of a more effective therapeutic strategy for patients who respond poorly to anti-PD1 therapy.
