Treadwell Announces Initiation of Patient Dosing in TWT-203, a Phase 1b/2 study of TTK Inhibitor, CFI-402257, in Patients with ER+/Her2- Breast cancer

NEW YORK and HONG KONG,June 14,2022 -- Treadwell Therapeutics,a clinical-stage biotechnology company developing novel medicines for unmet needs in cancer,today announced the initiation of patient dosing in TWT-203,its Phase 1b/2 study to evaluate CFI-402257,an oral,best-in-class inhibitor of Threonine Tyrosine Kinase (TTK,also known as MPS1) in patients with advanced solid tumors and ER+/Her2- breast cancer. Dosing of the first patient in the trial commenced June 8that START Mountain Region in Salt Lake City,Utah.

"Inhibition of TTK,a key mitotic checkpoint,with CFI-402257 represents a novel treatment approach for ER+/Her2-breast cancer,particularly in the context of CDK4/6 inhibitor failure" said Principal Investigator,Dr. Justin A. Call,MD,Director of Clinical Researchat START Mountain Region in Salt Lake City,Utah.

"We are excited about the initiation of TWT-203 with our potent and selective TTK inhibitor," said Dr. Michael Tusche,Treadwell co-CEO. "Previous clinical studies have demonstrated that CFI-402257 has a tolerable safety profile and confirmed responses in ER+/Her2- breast cancer after progression on CDK4/6 inhibitors. We look forward to the continued development of this molecule in breast cancer."

The Phase 1b/2 clinical trial of CFI-402257 is an open-label,multi-center,dose optimization study designed to assess the safety,tolerability,pharmacokinetic and pharmacodynamic profiles of CFI-402257 as a single agent in advanced solid tumors or in combination with fulvestrant in ER+/Her2- Breast Cancer patients after disease progression on prior CDK4/6 inhibitor and endocrine therapy. The trial will enrol approximately 40 patients at up to 10 sites in the United States. It will include a dose confirming portion in advanced solid tumors and expansions at the Recommended Phase 2 dose as a monotherapy in solid tumors and in combination with fulvestrant in breast cancer patients.

About Treadwell Therapeutics

Treadwell Therapeutics is a clinical-stage multi-modality oncology company developing novel medicines to address unmet needs in patients with cancer. The Company's internally developed clinical pipeline includes CFI-400945 (PLK4 inhbitor),CFI-402257 and CFI-402411 (HPK1 inhibitor). Treadwell also has a robust pre-clinical pipeline with multiple biologic and next generation TCR based autologous cell therapy programs. For more information,please visit www.treadwelltx.com.