Skin Cancers in Organ Transplant Recipients

Merkel cell carcinoma (MCC) is a lethal, virus-associated cancer that lacks effective therapies for advanced disease. Agents blocking the PD-1/PD-L1 pathway have demonstrated objective, durable tumor regressions in patients with advanced solid malignancies and efficacy has been linked to PD-L1 expression in the tumor microenvironment. To investigate whether MCC might be a target for PD-1/PD-L1 blockade, we examined MCC PD-L1 expression, its association with tumor-infiltrating lymphocytes (TILs), Merkel cell polyomavirus (MCPyV), and overall survival. Sixty-seven MCC specimens from 49 patients were assessed with immunohistochemistry for PD-L1 expression by tumor cells and TILs, and immune infiltrates were characterized phenotypically. Tumor cell and TIL PD-L1 expression were observed in 49% and 55% of patients, respectively. In specimens with PD-L1(+) tumor cells, 97% (28/29) demonstrated a geographic association with immune infiltrates. Among specimens with moderate-severe TIL intensities, 100% (29/29) demonstrated PD-L1 expression by tumor cells. Significant associations were also observed between the presence of MCPyV DNA, a brisk inflammatory response, and tumor cell PD-L1 expression: MCPyV(-) tumor cells were uniformly PD-L1(-). Taken together, these findings suggest that a local tumor-specific and potentially MCPyV-specific immune response drives tumor PD-L1 expression, similar to previous observations in melanoma and head and neck squamous cell carcinomas. In multivariate analyses, PD-L1(-) MCCs were independently associated with worse overall survival (hazard ratio 3.12; 95% CI, 1.28-7.61; p=0.012). These findings suggest that an endogenous immune response promotes PD-L1 expression in the MCC microenvironment when MCPyV is present, and provide a rationale for investigating therapies blocking PD-1/PD-L1 for patients with MCC.

Background: Cancer immunotherapy, such as anti-cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) and anti-programmed death 1 (PD-1), has revolutionized the treatment of malignancies by engaging the patient's own immune system against the tumor rather than targeting the cancer directly. These therapies have demonstrated a significant benefit in the treatment of melanomas and other cancers. Summary: In order to provide an extensive overview of the renal toxicities induced by these agents, a Medline search was conducted of published literature related to ipilimumab-, pembrolizumab-, and nivolumab-induced kidney toxicity. In addition, primary data from the initial clinical trials of these agents and the FDA adverse reporting system database were also reviewed to determine renal adverse events. Acute interstitial nephritis (AIN), podocytopathy, and hyponatremia were toxicities caused by ipilimumab. The main adverse effect associated with both the PD-1 inhibitors was AIN. The onset of kidney injury seen with PD-1 inhibitors is usually late (3-10 months) compared to CTLA-4 antagonists related renal injury, which happens earlier (2-3 months). PD-1 as opposed to CTLA-4 inhibitors has been associated with kidney rejection in transplantation. Steroids appear to be effective in treating the immune-related adverse effects noted with these agents. Key Message: Although initially thought to be rare, the incidence rates of renal toxicities might be higher (9.9-29%) as identified by recent studies. As a result, obtaining knowledge about renal toxicities of immune checkpoint inhibitors is extremely important.