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Treadwell Therapeutics Advances Phase I TTK Inhibitor to Breast Cancer Subpopulations

NEW YORK – Treadwell Therapeutics said on Friday that its TTK inhibitor CFI-402257 is being studied in three cohorts in the dose expansion portion of a Phase I study, and two of the cohorts will enroll biomarker-defined breast cancer subpopulations.

The Phase I study included a dose escalation portion, which has been completed, and a dose expansion portion, which is now enrolling 52 patients at several sites in Canada in three arms. One of the cohorts is enrolling patients with estrogen receptor-positive, HER2-negative breast cancer patients who will receive fulvestrant and CFI-402257 after failing on a CDK4/6 inhibitor. The second cohort involves triple-negative breast cancer patients (negative for HER2, estrogen, and progesterone receptors). The third cohort will enroll patients with other types of solid tumors.

Treadwell Chief Scientific Officer and Cofounder Mark Bray said in a statement that the New York-based clinical-stage biotech has seen "compelling early signs of clinical activity" of CFI-402257 in the dose escalation portion of the Phase I study.

TTK is overexpressed in multiple cancers and the biomarker is associated with worse prognosis. With CFI-402257, Treadwell is specifically hoping to target TTK in estrogen receptor-positive, HER2-negative breast cancer patients who need new treatment options after they become resistant to CDK4/6 inhibitors.

"CFI-402257 is a … potent inhibitor of TTK, a critical component of the cancer cell's maintenance of genomic integrity and survival, which may be a key vulnerability of tumors that are resistant to CDK4/6 inhibitors," Bray said.

Philippe Bedard at the Princess Margaret Cancer Centre in Toronto is the study's primary investigator; John Hilton at the Ottawa Hospital Cancer Center and Daniel Renouf at the British Columbia Cancer Agency are co-investigators.