On September 16, 2025 Crossbow Therapeutics, Inc., a biotechnology company focused on advancing T-Bolt therapies, a novel class of antibody therapeutics, reported dosing of the first participant in its CROSSCHECK-001 Phase 1 clinical trial of CBX-250, a first-in-class, potent, and specific T-cell engager (TCE) for the treatment of myeloid malignancies (Press release, Crossbow Therapeutics, SEP 16, 2025, View Source [SID1234656014]).

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"Patients with relapsed or refractory myeloid malignancies urgently need new treatment options, and CBX-250 offers a novel approach," said Briggs Morrison, M.D., Chief Executive Officer of Crossbow. "The preclinical profile of CBX-250 and its novel targeting strategy bolster our confidence as we begin to bring the expansive potential of our T-Bolt platform to patients."

CBX-250 is the first candidate developed through Crossbow’s T-Bolt platform, a portfolio of novel TCE molecules that uniquely target peptide-loaded human leukocyte antigen (pHLA) complexes on tumor cells, using antibodies that mimic T-cell receptors (TCR-mimetics). Specifically, CBX-250 targets a cathepsin G pHLA complex, abundantly expressed on leukemic cells, but not normal cells. The Phase 1, open-label, dose-escalation CROSSCHECK-001 study is the first clinical trial for Crossbow and the T-Bolt platform. The study is evaluating the safety, tolerability, and preliminary clinical activity of CBX-250 in patients aged 12 years and older with relapsed or refractory acute myeloid leukemia (AML), high-risk myelodysplastic syndrome (HR-MDS), and chronic myelomonocytic leukemia (CMML).

AML, one of the most common myeloid malignancies, is primarily a disease of older adults, with an average patient age of 68 years. In the United States, the estimated incidence of AML exceeds 22,000 new cases each year, and the five-year survival rate is approximately 33%.1 In AML patients, relapse is common within the first year of achieving complete remission, occurring in more than 50% of patients after induction chemotherapy, the current standard of care.2 Those with relapsed or refractory AML have an especially poor prognosis, underscoring the urgent need for potent therapies directed against novel tumor-selective therapeutic targets.

CBX-250 was developed through an ongoing strategic collaboration between Crossbow and The University of Texas MD Anderson Cancer Center. Crossbow designed and is conducting the CROSSCHECK‑001 clinical study, which is investigating CBX-250 on a fixed step-up dosing schedule. The company expects initial clinical data from CROSSCHECK-001 in 2026.

For additional trial details, visit the CROSSCHECK-001 study page on ClinicalTrials.gov.