t-cell-engagers
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Vir Biotechnology’s Second Act Comes With a Mask
After COVID antibodies and a failed flu trial, Vir is betting on hepatitis delta and cancer drugs designed to switch on inside tumors. Its comeback has partners and cash. The decisive clinical tests are still ahead.
CytomX Therapeutics
CytomX Therapeutics is a clinical-stage, oncology-focused biopharmaceutical company in South San Francisco that engineers conditionally activated antibody therapeutics through its proprietary PROBODY platform. By masking a drug's binding site and unmasking it only in the tumor microenvironment - where specific proteases cut a cleavable linker - CytomX aims to hit cancer targets that are otherwise too toxic to drug, widening the therapeutic window for antibody-drug conjugates, T-cell engagers and cytokines. Its wholly owned pipeline is led by CX-2051, an EpCAM-targeting PROBODY ADC for metastatic colorectal cancer, alongside masked interferon CX-801 and T-cell engager CX-904, and it partners its technology with Amgen, Astellas, Bristol Myers Squibb, Moderna and Regeneron.
Clasp Therapeutics
Clasp Therapeutics is a clinical-stage immuno-oncology company building off-the-shelf, antibody-like T cell engagers that target cancer driver mutations presented on tumor cells via HLA. Spun out of Johns Hopkins and co-founded by cancer-genetics pioneer Bert Vogelstein and immunotherapy leader Drew Pardoll, Clasp uses its proprietary pHLAre platform to redirect a patient's own T cells to kill tumors with what the company calls absolute specificity - hitting mutant peptides found only on cancer cells while sparing healthy tissue. The company launched publicly in March 2024 with a $150 million Series A and dosed its first patient in April 2025.
Crossbow Therapeutics, Inc.
Crossbow Therapeutics is a Cambridge, Massachusetts biotechnology company building a new class of cancer immunotherapies. Its T-Bolt platform engineers TCR-mimetic antibodies - T-cell engagers that recognize tiny peptide fragments displayed on a cancer cell's surface (peptide-HLA complexes), opening up intracellular proteins that conventional antibodies cannot reach. The lead program, CBX-250, is a first-in-class T-cell engager in a Phase 1 trial for relapsed or refractory myeloid malignancies. Backed by more than $157M in venture funding, Crossbow aims to expand the universe of targetable cancer antigens.