A phase 1 study of CBX-663, a TCR-mimetic antibody, in patients with myeloid diseases

In September 2025, TAP made an equity investment in Crossbow Therapeutics to "Support Clinical Development of CBX-250 in Relapsed/Refractory AML, MDS and CMML."

Crossbow Therapeutics is a biotechnology company determined to improve the lives of people with cancer by unlocking the therapeutic potential of T-cell receptor (TCR)-mimetic antibodies. The company’s T-Bolt™ therapies are next-generation, easily assembled immunotherapies directed with high precision at previously unreachable cancer cell targets.

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 (NCT06994676) 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 AML, high-risk MDS, CMML and CML.

CBX-663 is the second candidate developed through Crossbow’s T-Bolt™ platform. CBX-663 targets telomerase reverse transcriptase (TERT), a protein that drives tumor growth and is overexpressed in approximately 90% of all cancers.

The Phase 1, open-label, dose-escalation TelOscope-001 study (NCT07779798) is evaluating the safety, tolerability, and clinical activity of CBX-663 in patients with relapsed or refractory myeloid malignancies, advanced solid tumors, or recurrent or progressive glioblastoma multiforme.