Abstract 6748: Intramuscular delivery of tumor associated antigen DNA vaccines elicits strong cellular immune response, delays tumor growth and prolongs survival
Authors: Rayavara Kempaiah , Henderson John , Kinsella Meredyth , Kim Jessica , Matar Majed , Sood Subeena , Signer Olivia , Bellmon Chelsey , Le Goff Corinne , Anwer Khursheed , Boyer Jean 
Published: March 2024

Abstract
The development of effective cancer vaccines that can trigger strong and enduring memory T cell responses against specific tumor associated antigens (TAAs) is crucial for advancing immunotherapy. DNA-based cancer vaccines have shown promise in generating precise and long-lasting immune responses. In particular DNA vaccines are capable of inducing both humoral and cellular immune responses. In this study, we aimed to investigate the effectiveness of DNA vaccines targeting the mouse Tyrosine-related protein-2 (Trp2) and human New York esophageal squamous cell carcinoma 1 (NY-ESO-1) TAAs in mouse melanoma model. These DNA vaccines were formulated with a functionalized polymer designed to protect DNA from degradation and improve its bioavailability. DNA vaccines targeting both mouse Trp2 (pVACTR) and human NYESO-1 (pVACNY) were constructed. A mouse melanoma cell line (B16F10-NY) overexpressing human NYESO-1 was also generated and demonstrated to induce tumors in C57BL/6 mice. Female C57BL/6 mice received two doses of intramuscular (i.m.) injection of formulated pVACTR or pVACNY or a combination thereof, formulated with the synthetic functionalized polymer, with a 3-week interval. The DNA vaccination induced a potent T cell response, as evidenced by ELISPOT assays showing strong IFN-γ secreting T cells against NYESO-1 and Trp2. Flow cytometry analysis of spleenocytes showed strong IFN-γ and TNF-α secreting CD4 T cells against NYESO-1. We further evaluated the prophylactic and therapeutic efficacy of DNA vaccines targeting both Trp2 and NYESO-1 using a murine syngeneic model. Animals were challenged with a lethal dose of B16F10-NY two weeks after the second immunization exhibited a significant (p&lt;0.0001) delay in tumor progression and a substantial increase in survival compared to the mock control group. In the therapeutic testing, animals challenged with B16F10-NY and subsequently vaccinated at 4, 11, and 25 days also demonstrated delayed tumor growth and prolonged survival. These findings indicate that formulated DNA vaccine delivered via i.m. triggers robust T cell responses and exhibit both prophylactic and therapeutic efficacy, leading to significantly prolonged survival and delayed tumor growth. A DNA-based vaccine independent of viral vector or device has potential to elicit potent anti-tumor responses with better safety and compliance.
Citation Format: Kempaiah Rayavara, John Henderson, Meredyth Kinsella, Jessica Kim, Majed Matar, Subeena Sood, Olivia Signer, Chelsey Bellmon, Corinne Le Goff, Khursheed Anwer, Jean Boyer. Intramuscular delivery of tumor associated antigen DNA vaccines elicits strong cellular immune response, delays tumor growth and prolongs survival [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 6748.