Clasp Therapeutics Shows Preclinical Data on Precision T Cell Engager for p53 Mutant Tumors at SITC

CAMBRIDGE, MA. & ROCKVILLE, MD.--Clasp Therapeutics, a biotechnology enterprise focused on precision in immuno-oncology through next-generation T cell engagers (TCEs), has unveiled promising data validating their lead program, CLSP-1025. CLSP-1025 is a half-life extended TCE aimed at targeting cancer cells expressing the p53 R175H mutant peptide, which is presented by HLA-A*02:01. This data will be showcased at the Society for Immunotherapy of Cancer’s (SITC) 39th Annual Meeting on November 8, 2024.

Clasp Therapeutics is pioneering an innovative method in developing TCEs that boast absolute tumor specificity, ensuring no off-tumor binding by targeting shared cancer neoantigens derived from oncogenic driver mutations. These mutations are presented by human leukocyte antigen (HLA) on cancer cells. The company’s proprietary pHLAre™ platform simulates the natural immune synapse by linking cancer cells with T cells through CD3 binding. This connection activates T cells, resulting in the potent targeting and destruction of cancer cells. CLSP-1025 specifically targets the p53 R175H mutation, which is common across numerous solid tumors, including colorectal, esophageal, gastric, gynecological, lung, pancreatic, and prostate cancers.

The data accumulated by Clasp supports the progression of CLSP-1025 into clinical trials. It is anticipated that CLSP-1025 will be the first TCE to target a shared cancer neoantigen in clinical settings, with the first human trial expected to commence in early 2025.

“Clasp was established to harness the absolute precision of immunotherapies, enhancing and extending the lives of cancer patients,” stated Chief Executive Officer Rob Ross, M.D. “With this promising preclinical data, we are eager to advance CLSP-1025 into clinical trials. Today’s presentation is a significant milestone in our mission to introduce a new class of precision TCEs that broaden the scope of immunotherapy.”

Key Data Highlights:

- Selectivity: CLSP-1025 shows high selectivity for the p53 R175H mutation presented on HLA-A*02:01. It specifically binds to the R175H mutant peptide without affecting the wildtype p53 and does not react with any other human peptides presented on HLA-A*02:01.

- Sensitivity: CLSP-1025 activates T cells and effectively kills patient-derived organoids, demonstrating efficacy at endogenous target expression levels.

- Activity: CLSP-1025 induces the regression of established tumors in vivo.

About Clasp Therapeutics, Inc.

Clasp Therapeutics is at the forefront of precision in immuno-oncology, developing next-generation T cell engagers (TCEs) that specifically target tumor-specific oncogenic driver mutations prevalent in difficult-to-treat cancers. Utilizing their innovative platform, Clasp Therapeutics identifies mutation-associated neoantigens and develops TCEs capable of selectively binding to HLA-presented peptides derived from these oncogenic drivers. These precise HLA redirecting engagers (pHLAre™ molecules) direct all T cell types to destroy the tumor. Clasp’s TCEs, due to their unique properties, are adaptable for use across various types of cancers with significant unmet needs.