Clasp Therapeutics Presents Comprehensive Preclinical Data Validating First-in-Class Precision T Cell Engager Against p53 Mutant Solid Tumors at SITC Annual Meeting

- CLSP-1025, Clasp’s first-in-class T cell engager (TCE) targeting mutant p53, demonstrates selectivity, sensitivity and activity across preclinical models

- Data support the clinical development of CLSP-1025, expected to be the first absolutely tumor-specific TCE in clinical development

Clasp Therapeutics, a biotechnology company bringing unparalleled precision to immuno-oncology using next-generation TCEs, today announced new data validating the potential of its lead program, CLSP-1025. CLSP-1025 is a half-life extended TCE targeting cancer cells expressing the p53^R175H mutant peptide presented by HLA-A*02:01. Data demonstrating the therapeutic potential of CLSP-1025 will be presented at the Society for Immunotherapy of Cancer’s (SITC) 39th Annual Meeting on November 8, 2024.

Clasp’s innovative approach focuses on developing TCEs with absolute tumor specificity (i.e., no anticipated off-tumor binding) by targeting shared cancer neoantigens derived from oncogenic driver mutations presented by human leukocyte antigen (HLA) on cancer cells. The company’s proprietary pHLAre™ platform mimics the natural immune synapse by bridging cancer cells and T cells through CD3 binding. This engagement activates T cells, resulting in potent targeting and destruction of cancer cells. CLSP-1025 targets the p53^R175H mutation, which is prevalent in a range of solid tumors such as colorectal, esophageal, gastric, gynecological, lung, pancreatic and prostate cancers.

Together, Clasp’s data support advancing CLSP-1025 into clinical trials. CLSP-1025 is expected to be the first TCE targeting a shared cancer neoantigen to reach the clinic, with the first-in-human trial anticipated to begin in early 2025.

“Clasp was built to bring absolute precision to the power of immunotherapies, thereby improving and extending the lives of people with cancer,” said Chief Executive Officer Rob Ross, M.D. “Building on this promising preclinical data, we look forward to advancing CLSP-1025 into the clinic. Today’s presentation marks a significant milestone in our mission to deliver a new class of precision TCEs that expand the reach of immunotherapy.”

Data Highlights:

• Selectivity: CLSP-1025 demonstrates high selectivity for p53^R175H presented on HLA-A*02:01
  • Specifically binds the R175H mutant peptide and spares wildtype p53;
  • No reactivity with any other human peptides presented on HLA-A*02:01;
• Sensitivity: CLSP-1025 activates T cells and effectively kills patient-derived organoids, demonstrating activity at endogenous target expression levels;
• Activity: CLSP-1025 induces the regression of established tumors in vivo.

About Clasp Therapeutics, Inc.

Clasp is pioneering precision in immuno-oncology through next-generation T cell engagers (TCEs) that target tumor-specific oncogenic driver mutations common across hard-to-treat cancers. Clasp’s platform identifies mutation-associated neoantigens and develops TCEs that can selectively bind HLA (human leukocyte antigen)-presented peptides derived from these oncogenic drivers. These innovative pHLAre^TM molecules, precise HLA redirecting engagers, direct all T cell types to destroy the tumor. With their unique properties, Clasp’s TCEs are adaptable for application across a variety of cancers with high unmet need. Please visit www.clasptx.com to learn more.

View source version on businesswire.com: https://www.businesswire.com/news/home/20241107258270/en/