Benzinga | Jan 10, 2022 07:26AM EST

Theseus Pharmaceuticals Announces First Patient Treated With THE-630 In Phase 1/2 Study In Patients with Advanced Gastrointestinal Stromal Tumors

Theseus Pharmaceuticals, Inc. (Theseus) (NASDAQ:THRX), a clinical stage biopharmaceutical company focused on improving the lives of cancer patients through the discovery, development and commercialization of transformative targeted therapies, today announced that the first patient has been treated in the Phase 1 portion of Theseus' ongoing Phase 1/2 study to evaluate lead candidate, THE-630, in patients with advanced gastrointestinal stromal tumors (GIST).

THE-630 is a pan-variant inhibitor of the receptor tyrosine kinase KIT. It is designed for patients with advanced GIST whose cancer has developed resistance to earlier lines of therapy by accruing mutations that render those therapies ineffective. In GIST, these mutations occur most often in the KIT protein, where a patient can have multiple KIT mutations simultaneously, leading to complex disease heterogeneity. Pan-variant inhibitors like THE-630 are single therapeutic molecules designed to inhibit all known, clinically relevant mutations of a target protein to address the problem of disease heterogeneity that contributes to treatment resistance. In preclinical studies, THE-630 demonstrated potent in vitro and in vivo activity against all major classes of KIT activating and resistance mutations in GIST. Moreover, THE-630 achieved predicted pan-variant KIT inhibitory blood concentrations at tolerable doses and was associated with significant anti-tumor activity.

"Patients with unresectable or metastatic GIST who have exhausted standard therapies have limited treatment options and poor clinical outcomes. GIST disease progression remains largely KIT-dependent even after multiple lines of therapy, and a significant unmet need remains for these patients," said Suzanne George, M.D., Clinical Director, Center for Sarcoma and Bone Oncology at Dana-Farber Cancer Institute. "I am excited to work with Theseus on this first-in-human trial of THE-630, and I look forward to evaluating its clinical potential to address the needs of patients with advanced GIST."

"The initiation of our Phase 1/2 trial in patients with previously-treated advanced GIST is an important milestone as we begin to characterize THE-630 in the clinic," said David Kerstein, M.D., Chief Medical Officer at Theseus. "We believe THE-630 has a differentiated profile of pan-variant activity against KIT and we look forward to exploring a number of GIST settings where pan-variant inhibition may translate into meaningful clinical benefit--from the fifth-line, where no standard therapies exist, to earlier lines of therapy, such as the second-line, where current standard of care yields less than optimal outcomes."