Abstract 4441: Bifunctional immunotherapeutic HCW9218 facilitates recruitment of immune cells from tumor draining lymph nodes to promote antitumor activity and enhance checkpoint blockade efficacy in solid tumors
Authors: George Varghese , Chaturvedi Pallavi , Shrestha Niraj , Kanakraj Leah , Gilkes Crystal , Encalada Nicole , Wang Meng , Zhu Xiaoyun , Liu Bai , Rhode Peter , Wong Hing C. 
Published: April 2023

Abstract
Immunotherapeutics that aid in boosting natural immune defenses against cancers have revolutionized cancer treatment. Previously, we reported a novel heterodimeric bifunctional fusion molecule, HCW9218, designed using soluble tissue factor (TF)-based scaffold technology comprising extracellular domains of the human transforming growth factor-β (TGF-β) receptor II and a human interleukin (IL)-15/IL-15 receptor α complex which exhibited both immune cell stimulatory and TGF-β neutralizing properties. Herein, we showed in two different syngeneic murine tumor models (B16F10, 4T1) that subcutaneous treatment with HCW9218 induces a proliferative burst of CD8+ T cells and NK cells in blood and a subsequent infiltration of these cells into established tumors. In vivo imaging of 4T1 tumor-bearing mice after treatment showed that HCW9218 was present both in lymph nodes and established tumors up to 24hr following treatment. Comprehensive analysis of tumor infiltrating lymphocytes (TILs) showed that HCW9218 mediated antitumor activity by expanding TCF+TIM3− ‘progenitor exhausted’ (Tpex) CD8+ T cells in tumors. Sphingosine-1-phosphate receptor blockade resulted in decreased tumor infiltration of CD8+ Tpex in B16F10 and 4T1 tumor-bearing mice indicating that these cells originate from tumor draining lymph nodes (TdLN). Increased ‘terminally exhausted‘ TCF-1−TIM3+ (Tex) CD8+ TILs were also observed in tumors of HCW9218-treated mice indicating increased antitumor activity. Tumor transplantation experiments further confirmed the mechanism of HCW9218 antitumor activity by increasing influx of CD45.1+ CD8+ T cells into transplanted tumors from CD45.2+ mice. Additionally, HCW9218 enhanced the therapeutic efficacy of PD-L1 treatment by increasing the infiltration of activated/memory CD8+ T cells into B16F10 tumors in mice leading to significant reduction in tumor volume. Collectively, the results of this study demonstrated that HCW9218 treatment of mice bearing solid tumors resulted in modulating the TdLN immune landscape and invigorating T cells for enhanced checkpoint blockade therapy. HCW9218 are currently in two clinical trials (clinicaltrials.org: NCT05322408, NCT05304936) against chemo-resistant/refractory solid tumors.
Citation Format: Varghese George, Pallavi Chaturvedi, Niraj Shrestha, Leah Kanakraj, Crystal Gilkes, Nicole Encalada, Meng Wang, Xiaoyun Zhu, Bai Liu, Peter Rhode, Hing C. Wong. Bifunctional immunotherapeutic HCW9218 facilitates recruitment of immune cells from tumor draining lymph nodes to promote antitumor activity and enhance checkpoint blockade efficacy in solid tumors. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 4441.