PD-1 inhibitor plus oncolytic vaccinia virus is a safe and effective treatment option for metastatic renal cell carcinoma.

"Declarations Ethics approval and consent to participateAll animal experiments were performed with the approval of the Institutional Animal Care and Use Committee (IACUC) of the Yonsei University Health System (IACUC No. 2020–0006). Consent for publicationNot applicable. Competing interestsThe authors declare no competing interests. Competing interests The authors declare no competing interests."

"Funding This study was supported by a grant from the Korea Health Technology R&D Project through the Korea Health Industry Development Institute (KHIDI), funded by the Ministry of Health & Welfare, Republic of Korea (grant number: HI17C1095); National Research Foundation of Korea (NRF) grants funded by the Korean government (MSIT) (grant numbers:2019R1A2C1002863 and 2022R1A2C2003831); a young researcher grant from the Korean Urological Oncology Society (KUOS) (grant number: KUOS 22 − 01); and a faculty research grant from Yonsei University College of Medicine (grant number: 6-2020-0106)."