Clinicopathological Features, MCPyV Status and Outcomes of Merkel Cell Carcinoma in Solid-Organ Transplant Recipients: A Retrospective, Multicenter Cohort Study
May 15, 2022
Journal of the European Academy of Dermatology and Venereology
May 15, 2022
This study looked at 77 MCC patients who were diagnosed and treated in Europe. Thirty of the 77 patients were immune suppressed because of medications they take to prevent rejection of a transplanted organ (often a kidney). As has been found in some prior studies, a higher fraction of the immune suppressed patients had virus-NEGATIVE MCC, as compared to the control patients who were not immune suppressed. Specifically, only 33% of the immune suppressed patients had MCC caused by the Merkel polyomavirus, as compared to 91% of the immune competent patients who had virus-positive MCC. We simply do not understand why this would be the case, because the immune system plays a very important role in controlling MCC whether it is caused by the virus or by sunlight. This additional study validates prior smaller studies that had similar findings. It also suggests we have yet another mystery to try to unravel in the coming years.
Background: The proportion of Merkel cell carcinomas (MCCs) in solid-organ transplant recipients (SOTR) harboring Merkel cell polyomavirus (MCPyV) is unknown, as are factors affecting their outcomes.
Objective: To describe clinicopathologic features of MCC in SOTR, investigate the tumoral MCPyV-status and identify factors associated with tumor outcomes.
Methods: Retrospective, international, cohort-study. MCPyV-status was investigated by immunohistochemistry and polymerase chain reaction.
Results: Thirty SOTR and 44 consecutive immunocompetent patients with MCC were enrolled. SOTR were younger at diagnosis (69 vs 78 years, p<.001). Thirty-three percent of SOTR MCCs were MCPyV-positive vs 91% of immunocompetent MCCs (p=.001). Solid-organ transplantation was associated with an increased cumulative incidence of progression (SHR: 3.35 [1.57-7.14], p=.002), MCC-specific mortality (SHR: 2.55 [1.07-6.06], p=.034) and overall mortality (HR: 3.26 [1.54-6.9], p=.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=.008 and SHR: 3.6 [1.1-12], p=.032, respectively) in SOTR.
Limitations: Retrospective design and heterogeneity of SOTR cohort.
Conclusions: MCPyV appears to play a less prominent role in the etiopathogenesis 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.