**6. Conclusions**

The discovery of T cell checkpoint inhibitors and oncolytic virotherapy has changed the paradigm of oncologic treatment for some cancer types and showed a transition pattern from conventional therapies towards immuno-oncology. Oncolytic viruses can induce anti-tumor immunity and lead to the infiltration of TILs. In turn, a checkpoint blockade can prevent inhibition of T cell activity. Therefore, the combination of those agents seems to be a potent treatment regimen to combat immunogenic cancer types such as melanoma.

**Author Contributions:** Conceptualization, L.K., M.G.; writing—original draft, M.G., L.K., L.B.; writing—review and editing, L.K., M.G., L.B., M.S., K.P., M.W., S.S., P.C. All authors have read and agreed to the published version of the manuscript.

**Funding:** L.K. was supported by the National Science Centre, Poland (SONATINA (2019/32/C/NZ7/00156)) and National Institute of Public Health–National Institute of Hygiene in Poland (1BWBW/19). M.G. was supported by PRID-J (Grant Number: GARO\_SID19\_02) funded by University of Padua.This publication is based upon work from COST Action CA 17140 "Cancer Nanomedicine from the Bench to the Bedside" supported by COST (European Cooperation in Science and Technology) (L.K., M.G.).

**Conflicts of Interest:** The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results.
