Clasp Emerges with $150M Series A Financing to Advance T Cell Engagers

T cells fighting cancer cell

Pictured: Illustration of T cells attacking cancer/iStock, Design Cells

Clasp Therapeutics launched Wednesday with $150 million in Series A financing to develop a portfolio of next-generation immunotherapies that are both personalized and off-the-shelf to target hard-to-treat tumors. 

Based in Cambridge, Massachusetts and Rockville, Maryland, the startup garnered attention from big name investors like Novo Holdings, Third Rock and Catalio, who led the funding round, with participation from the American Cancer Society’s philanthropic fund and others.

At the helm is CEO Robert Ross, whose previous company, Surface Oncology, was acquired by Coherus in July 2023 for $65 million. Before that, he was head of oncology at bluebird bio. 

Clasp is developing T cell engagers (TCE), a cancer fighting tool that has been gaining in popularity. Gilead struck a deal earlier this month with Merus worth up to $1.5 billion for its T-cell engager antibodies. 

Most T cell engagers link to proteins on the surface of the cell. But these proteins are often also found on healthy cells, leading to off-target effects. Where Clasp potentially stands apart is in its design to target proteins found inside the cancer cell by grabbing onto peptides, or mutated protein fragments, displayed by specialized human leukocyte antigen (HLA) molecules. The TCE brings the T cell into contact with the tumor cell, triggering a destructive immune response. 

Each of Clasp’s TCEs will be tailored for a specific mutation and patient HLA type, which identifies antigens on the surface of cells and tissues. Selectively profiling patients to match their treatments means the treatments potentially can have the efficacy of a personalized therapy, with the convenience and faster time-to-treatment of off-the-shelf therapies. 

The funds from the initial raise should be enough to bring Clasp’s initial candidates to the clinic to gather early proof-of-concept data, according to the company. In the current market, Ross believes early efficacy data is key. 

“The business model for small oncology biotech now dictates that you need to be seeing activity early,” Ross told STAT News

The company’s initial target or a timeline for when the company expects to submit its IND to begin trials has not yet been disclosed. 

Kate Goodwin is a freelance life science writer based in Des Moines, Iowa. She can be reached at and on LinkedIn 

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