Abstract 5215: MOA study of KD050, an anti-PD-1/IL-15 bi-functional antibody selectively targeted PD-1 positive tumor-infiltrating lymphocytes resulted in robust anti-tumor activity and low systemic toxicity

Abstract Anti-tumor efficacy, treated by immune checkpoint inhibitor (ICI) such as anti-PD-1/PD-L1 antibody or immunostimulatory cytokine IL-2 or IL-15, has been confirmed clinically in multiple cancer indications, but both treatments have some limitations. Only ~30% patients respond to ICI treatment, and cytokines have been associated with short half-lives and systemic toxicities. Kadmon has established a cytokine fusion antibody platform to synergize the antibody and cytokine anti-tumor activity, extend cytokine serum half-life and reduce systemic toxicity. One of novel asset in this platform is KD050, an anti-PD-1/IL-15 bi-functional antibody with strong PD-1 antagonist function, but lower lymphocyte stimulation enabled by a novel mutation on the IL-15. KD050 was designed to deliver PD-1-mediated, avidity-driven lymphocyte stimulation to PD-1+ tumor-infiltrating lymphocytes (TIL) while minimally affecting circulating peripheral natural killer (NK) cells and T cells. We have reported previously (SITC2020, Abstract ID: 573) that KD050 (also called mut-1N-IL-15/38B2) showed robust anti-tumor efficacy and low systemic toxicity to treat hPD-L1-CT26 tumor inoculated in hPD-1/hPD-L1 transgenic BALB/c mice. Here, we conducted the MOA study in the same animal model by treating the mice with vehicle, KD050, PD-1 antibody (38B2), non-target counterpart of KD050 (ntKD050) and combination of 38B2 and ntKD050. The peripheral blood, draining lymph nodes and tumors were isolated at day 7 after the treatment. Immune cell types were analyzed by FACS for all isolated samples, and Nanostring RNA sequence and IHC was performed for the isolated tumors. Compared to the other treatments, we observed significant higher effector memory CD8 T cells (EM CD8 T), expanded Granzyme B+ and CD8+ T cells, and high CD8/CD4 ratio in tumor when treated with KD050. Tumor Differential Gene Expression (DGE) analysis revealed that many lymphocyte markers were specific to KD050. Functional Enrichment by Gene Set Variation Analysis (GSVA) in tumor showed that many cell types especially CD8 T cells, cytotoxic cells and Th1 cells were statistically (p. adjust < 0.05) significant higher relative to other treatments. We further found that binding of KD050 to PD-1 mediated delivery of IL15 to PD-1+ T cells and the simultaneous binding of KD050 to PD-1 and IL-2 receptor βγ (IL-2Rβγ) resulted in enhanced potency of IL-2Rβγ activation and anti-tumor activity. In conclusion, we demonstrated that KD050 treatment activated different gene pathways which were unique from PD-1 monospecific antibody 38B2, ntKD050 alone or combined with 38B2. These findings indicated that KD050 may have potential to benefit patients that were not responsive to the PD-1/PD-L1 treatment or cytokine treatment. Citation Format: Zhanna Polonskaya, Tzu-Pei Chang, Stella Martomo, Xenia Luna, Zhikai Zhang, Stanley Ng, Alessandro Mora, Jeegar P. Patel, Dan Lu. MOA study of KD050, an anti-PD-1/IL-15 bi-functional antibody selectively targeted PD-1 positive tumor-infiltrating lymphocytes resulted in robust anti-tumor activity and low systemic toxicity [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5215.