Combination therapy with CAR T cells and oncolytic viruses: a new era in cancer immunotherapy

Chimeric antigen receptor (CAR) T-cell therapy is an encouraging and fast-growing platform used for the treatment of various types of tumors in human body. Despite the recent success of CAR T-cell therapy in hematologic malignancies, especially in B-cell lymphoma and acute lymphoblastic leukemia, the application of this treatment approach in solid tumors faced several obstacles resulted from the heterogeneous expression of antigens as well as the induction of immunosuppressive tumor microenvironment. Oncolytic virotherapy (OV) is a new cancer treatment modality by the use of competent or genetically engineered viruses to replicate in tumor cells selectively. OVs represent potential candidates to synergize the current setbacks of CAR T-cell application in solid tumors and then and overcome them. As well, the application of OVs gives researches the ability to engineer the virus with payloads in the way that it selectively deliver a specific therapeutic agents in tumor milieu to reinforce the cytotoxic activity of CAR T cells. Herein, we made a comprehensive review on the outcomes resulted from the combination of CAR T-cell immunotherapy and oncolytic virotherapy for the treatment of solid cancers. In the current study, we also provided brief details on some challenges that remained in this field and attempted to shed a little light on the future perspectives.