Complete remission from intralesional talimogene laherparepvec for regionally advanced Merkel cell carcinoma in an immunocompromised solid organ transplant patient

Merkelcell.org Summary

Managing MCC that recurs in patients who are immune suppressed due to an organ transplant (kidney, heart, etc) is a special challenge, as the immune therapies that block the PD1 pathway will cause rejection of the transplanted organ. This case shows the capacity of local immune therapy (with an injected, modified Herpes virus called T-Vec that selectively kills cancer cells) to be effective against MCC while not threatening the transplanted organ. Many new locally-injected immune-stimulating drugs are being developed and they will likely be safer than systemic agents for patients with immune issues such as an organ transplant or auto-immune disease.

Abstract

Merkel cell carcinoma (MCC) is a rare aggressive cutaneous neuroendocrine tumor with a high risk of locoregional recurrence and distant metastasis. Immune checkpoint inhibitors (ICIs), avelumab and pembrolizumab, have been approved by the US Food and Drug Administration for the treatment of advanced MCC.1

Talimogene laherparepvec (T-VEC) is a genetically modified type 1 oncolytic herpes simplex virus encoding granulocyte-macrophage colony-stimulating factor. It has been approved by the US Food and Drug Administration for the local treatment of unresectable cutaneous, subcutaneous, and nodal melanoma lesions; however, the clinical benefits of T-VEC in immunosuppressed patients with MCC, including solid organ transplant recipients, are not yet known. We report a case of surgically unresectable stage IIIB MCC in a patient with a history of heart transplantation and prior radiation, who had a complete response to intralesional T-VEC.