Abstract 3505: CLN-617 is an IL-2/IL-12 fusion protein with a collagen-anchoring domain that induces potent systemic anti-tumor immunity upon intra-tumoral administration
Authors: Mehta Naveen K. , Li Bochong , Rakhra Kavya , Wittrup K Dane , Baeuerle Patrick A. , Michaelson Jennifer S. 
Published: June 2022

Despite strong anti-tumor immune responses in the clinic, cytokine therapy for cancer treatment, has remained limited in use due to its narrow therapeutic window. Moreover, anti-tumor immunity is typically driven through multiple cytokines acting in concert in a local tumor microenvironment (TME) via autocrine or paracrine signaling. Yet most cytokine therapies focus on systemic delivery of individual cytokines causing adverse events without achieving therapeutic doses at the tumor site. Recently, intratumoral (IT) delivery of cytokines such as IL-2 and IL-12 anchored to collagen in the TME has resulted in promising anti-tumor efficacy with minimal toxicity in multiple murine tumor models, and remarkably also in spontaneously occurring large canine tumors (unpublished data). Cullinan Amber is developing CLN-617, a fusion protein that uniquely combines IL-2 and IL-12 with albumin and a collagen-binding domain in a single polypeptide. CLN-617 aims to increase cytokine persistence and retention in the TME upon IT administration and thus improve tolerability. Data presented in this abstract is generated using a murine surrogate, mCLN-617.

mCLN-617 retains bioactivity of both IL-2 and IL-12 in the presence of collagen binding. Upon IT injection into B16F10 tumor-bearing mice, systemic drug levels of mCLN-617 were &lt 5% compared to mice dosed via intravenous (IV) administration. When IL-2/IL-12 fusion proteins lacking a collagen-binding domain were injected IT in B16F10-bearing mice, 60% of mice were euthanized due to severe body weight loss, whereas mCLN-617-treated mice maintained their body weight. In checkpoint-refractory B16F10 and MC38 models, mCLN-617 demonstrated 95% tumor growth inhibition and 100% CRs, respectively. All mice cured of their primary MC38 tumors were either protected from re-challenge or showed delayed tumor growth kinetics. Notably, 70% CRs were observed in the MC38 model after a single-dose treatment of mCLN-617. In mice bearing dual-flank MC38 tumors, only one of which was treated IT, 90% of treated tumors and 100% of distal untreated tumors were eliminated when mCLN-617 was combined with an anti-PD1 antibody, demonstrating a curative abscopal response. Of note, mCLN-617 monotherapy in the treated tumor also significantly delayed the growth of distal untreated tumors. Our human lead candidate CLN-617 is produced at high titers in CHO cells and is currently in IND enabling studies.

We have demonstrated that the use of collagen-binding domains for tumor retention enables safe and effective delivery of a combination of IL-2 and IL-12 in a single multifunctional molecule. The strong anti-tumor efficacy of mCLN-617 as a monotherapy and significant deepening of responses in combination with checkpoint blockade, together with a favorable tolerability profile, supports future clinical development of CLN-617.

Citation Format: Naveen K. Mehta, Bochong Li, Kavya Rakhra, K Dane Wittrup, Patrick A. Baeuerle, Jennifer S. Michaelson. CLN-617 is an IL-2/IL-12 fusion protein with a collagen-anchoring domain that induces potent systemic anti-tumor immunity upon intra-tumoral administration [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 3505.