Abstract Major challenges for CAR-T cell therapy in solid tumors include various limitations due to the issue of appropriate antigen selection, tumor heterogeneity, and the immune-suppressive tumor microenvironment (TME). To overcome these hurdles, we’ve developed a novel therapy, CLM-202 which is a combination therapy of oncolytic Newcastle disease virus (NDV) and NDV F protein-targeted CAR-T cell therapy (NDV F CAR-T). After NDV infects tumor cells, NDV envelope protein F is expressed on the tumor cell surface. NDV F CAR-T recognizes NDV F protein and kills the tumor cells. This approach can be applied to patients with various indications, regardless of the presence of the target protein. Using NDV to deliver antigens minimizes the risk of tumor recurrence due to tumor heterogeneity. Furthermore, it mitigates off-target toxicity by targeting oncolytic virus-derived proteins, not human proteins. Oncolytic NDV also triggers a potent immune response within the tumor microenvironment, thereby altering the immunosuppressive conditions of the tumor and improving CAR-T efficacy. Therefore, CLM-202 can be a multipurpose solution for solid tumors. We have developed a second-generation CAR-T cell therapy, NDV F CAR-T, which can be used in combination with an oncolytic virus known as NDV. NDV F CAR-T is designed to specifically target the F protein expressed when cells are infected by NDV. It incorporates a single-chain variable fragment (scFv) derived from an antibody that can bind specifically to the F protein of NDV-infected cells. To assess the activity of NDV F CAR-T in tumor cells against a variety of solid tumors as indications, we conducted several experiments. We initially confirmed the expression of the F protein in NDV-infected tumor cells. We also conducted cytotoxicity tests to confirm NDV F CAR-T's ability to induce death in NDV-infected tumor cell lines. Furthermore, to assess the efficacy of NDV F CAR-T in an in vivo model, we established an orthotopic mouse model. In this model, we administered NDV via intratumoral injection, followed by the single-dose administration of NDV F CAR-T to perform the efficacy test. We have confirmed that NDV infects all solid tumor cell lines representing different indications and induces the expression of the F protein in infected tumor cells. Furthermore, we have observed that NDV infection in these diverse tumor cells results in robust tumor cell-killing activity by NDV F CAR-T and the subsequent activation of CAR-T. Moreover, in an orthotopic mouse model, we have demonstrated that the administration of NDV followed by NDV F CAR-T induces potent tumor growth inhibition. In summary, our research proposes a novel therapeutic strategy, CLM-202 that utilizes NDV F CAR-T and NDV to overcome the limitations of CAR-T cell therapy in solid tumors, including tumor heterogeneity and immune-suppressive tumor microenvironments. This approach aims to effectively treat a wide range of indications. Citation Format: Soyoung Choi, Kiwan Kim, Sangeun Lee, Jeongeun Choi, Song-Jae Lee, Yong Gu Lee, Jeonghun Kim, Hoyoung Lee, Kisoon Kim, Man-Seong Park, Seong-Won Song. Revolutionizing solid tumor treatment: Viral protein-targeted CAR-T with oncolytic virus [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 6656.

<b>Rationale:</b> Platinum-based chemotherapy is commonly used for treating solid tumors, but drug resistance often limits its effectiveness. Cancer-associated fibroblast (CAF)-derived extracellular vesicle (EV), which carry various miRNAs, have been implicated in chemotherapy resistance. However, the molecular mechanism through which CAFs modulate cisplatin resistance in oral squamous cell carcinoma (OSCC) is not well understood. We employed two distinct primary CAF types with differential impacts on cancer progression: CAF-P, representing a more aggressive cancer-promoting category, and CAF-D, characterized by properties that moderately delay cancer progression. Consequently, we sought to investigate whether the two CAF types differentially affect cisplatin sensitivity and the underlying molecular mechanism. <b>Methods:</b> The secretion profile was examined by utilizing an antibody microarray with conditioned medium obtained from the co-culture of OSCC cells and two types of primary CAFs. The effect of CAF-dependent factors on cisplatin resistance was investigated by utilizing conditioned media (CM) and extracellular vesicle (EVs) derived from CAFs. The impacts of candidate genes were confirmed using gain- and loss-of-function analyses in spheroids and organoids, and a mouse xenograft. Lastly, we compared the expression pattern of the candidate genes in tissues from OSCC patients exhibiting different responses to cisplatin. <b>Results:</b> When OSCC cells were cultured with conditioned media (CM) from the two different CAF groups, cisplatin resistance increased only under CAF-P CM. OSCC cells specifically expressed insulin-like growth factor binding protein 3 (<i>IGFBP3</i>) after co-culture with CAF-D. Meanwhile, <i>IGFBP3</i>-knockdown OSCC cells acquired cisplatin resistance in CAF-D CM. <i>IGFBP3</i> expression was promoted by GATA-binding protein 1 (<i>GATA1</i>), a transcription factor targeted by miR-876-3p, which was enriched only in CAF-P-derived EV. Treatment with CAF-P EV carrying miR-876-3p antagomir decreased cisplatin resistance compared to control miRNA-carrying CAF-P EV. On comparing the staining intensity between cisplatin-sensitive and -insensitive tissues from OSCC patients, there was a positive correlation between <i>IGFBP3</i> and <i>GATA1</i> expression and cisplatin sensitivity in OSCC tissues from patients. <b>Conclusion:</b> These results provide insights for overcoming cisplatin resistance, especially concerning EVs within the tumor microenvironment. Furthermore, it is anticipated that the expression levels of <i>GATA1</i> and miR-876-3p, along with <i>IGFBP3</i>, could aid in the prediction of cisplatin resistance.