Abstract B001: Removal of interstitial hyaluronan facilitates subcutaneous administration and lymphatic delivery of anti-CTLA4 antibody and improves anti- tumor efficacy

Abstract The tumor-draining lymph node (TDLN) modulates anti-tumor immunity. Targeting immune checkpoint blockade monoclonal antibodies (mAbs) to the TDLN via subcutaneous (SC) delivery has the potential to enhance efficacy and safety. Recombinant human hyaluronidase (rHuPH20; PH20) transiently removes hyaluronan at interstitial injection sites and is used to facilitate SC delivery of the large doses and volumes required for mAbs. We have previously shown that PH20 co-dosing improves the rate and extent of lymphatic absorption of SC mAbs. Here we investigate whether PH20 co-dosing improves the anti-tumor efficacy of SC anti-CTLA4 (αCTLA4) which targets T cell activation at the TDLN. Efficacy studies and immunophenotyping of the tumor and TDLN were conducted in syngeneic murine tumor models CT26/HAS and MC38/OVA. SC delivery significantly enhanced TDLN uptake of αCTLA4 compared to IV delivery and this was enhanced further by PH20 co-dosing. SC αCTLA4 ± PH20 also more effectively inhibited tumor growth than IV αCTLA4. Importantly, consistent with higher mAb uptake into the TDLN, SC delivery with PH20 enabled a reduction in αCTLA4 dose compared to SC alone or IV (similar efficacy at 3 to 8-fold lower doses). Efficacy improvements occurred concomitantly with greater, more sustained levels of cytotoxic effector CD8+ T cells at the tumor and CD62L+ stem-like CD8+ T cells at the TDLN. The efficacy advantage of SC delivery ± PH20 over IV was limited to TDLN- targeted mAbs. Combination therapy with a non-TDLN targeted mAb, αTIM3, was similarly efficacious across all dose routes. Overall, we report the potential utility of PH20 to improve TDLN-targeted immune checkpoint blockade beyond application as a SC administration enabler. Citation Format: Gracia Gracia, Enyuan Cao, Daniel Yuen, Vilena DM Ferreira, Moore Z Chen, Danielle Senyschyn, Justine D Mintern, Angus PR Johnston, David W Kang, Orlagh M Feeney, Christopher JH Porter. Removal of interstitial hyaluronan facilitates subcutaneous administration and lymphatic delivery of anti-CTLA4 antibody and improves anti- tumor efficacy [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Tumor Immunology and Immunotherapy; 2024 Oct 18-21; Boston, MA. Philadelphia (PA): AACR; Cancer Immunol Res 2024;12(10 Suppl):Abstract nr B001.