Clinicopathological features, MCPyV status and outcomes of Merkel cell carcinoma in solid-organ transplant recipients: a retrospective, multicentre cohort study

Background The proportion of Merkel cell carcinomas (MCCs) in solid-organ transplant recipients (SOTR) harbouring Merkel cell polyomavirus (MCPyV) is unknown, as are factors affecting their outcomes. Objective To describe clinicopathological features of MCC in SOTR, investigate the tumoral MCPyV-status and identify factors associated with tumour outcomes. Methods Retrospective, international, cohort-study. MCPyV-status was investigated by immunohistochemistry and polymerase chain reaction. Results A total of 30 SOTR and 44 consecutive immunocompetent patients with MCC were enrolled. SOTR were younger at diagnosis (69 vs. 78 years, P < 0.001). Thirty-three percent of SOTR MCCs were MCPyV-positive vs. 91% of immunocompetent MCCs (P = 0.001). Solid-organ transplantation was associated with an increased cumulative incidence of progression (SHR: 3.35 [1.57-7.14], P = 0.002), MCC-specific mortality (SHR: 2.55 [1.07-6.06], P = 0.034) and overall mortality (HR: 3.26 [1.54-6.9], P = 0.002). MCPyV-positivity and switching to an mTOR inhibitor (mTORi) after MCC diagnosis were associated with an increased incidence of progression (SHR: 4.3 [1.5-13], P = 0.008 and SHR: 3.6 [1.1-12], P = 0.032 respectively) in SOTR. Limitations Retrospective design and heterogeneity of SOTR cohort. Conclusions MCPyV appears to play a less prominent role in the aetiopathogenesis of MCC in SOTR. SOTR have a worse prognosis than their immunocompetent counterparts and switching to an mTORi after the diagnosis of MCC does not improve progression.

Automated summary

The objective of this study was to describe the clinicopathological features of Merkel cell carcinoma (MCC) in solid-organ transplant recipients (SOTR) and identify factors associated with tumor outcomes. The results showed that the proportion of MCC patients with Merkel cell polyomavirus (MCPyV) was low in SOTR, and solid-organ transplantation was associated with an increased incidence of progression, MCC-specific mortality, and overall mortality. In SOTR, MCPyV positivity and switching to an mTOR inhibitor (mTORi) were associated with an increased incidence of progression.