FDA grants Fast Track designation to PIKTOR plus paclitaxel for biomarker-selected advanced or recurrent endometrial cancer after platinum chemotherapy and ICI treatment.
Written By: Desai Dishali K. PharmD
Reviewed By: Pharmacally Editorial Team
The U.S. Food and Drug Administration (FDA) has granted Fast Track designation to the combination of sapanisertib and serabelisib (PIKTOR) with paclitaxel for the treatment of patients with advanced or recurrent endometrial cancer whose tumors harbor a PI3K/AKT/mTOR pathway alteration. The designation applies to patients who have previously been treated with platinum-based chemotherapy and an immune checkpoint inhibitor (ICI).
The designation highlights an investigational treatment approach being developed by Faeth Therapeutics for patients with advanced or recurrent endometrial cancer who have progressed after prior standard treatments. Faeth is currently evaluating PIKTOR in a Phase 2 study in second-line advanced endometrial cancer, with topline data expected by year-end 2026.
PIKTOR Targets Multiple Nodes of the PI3K/AKT/mTOR Pathway
PIKTOR is an investigational, proprietary, all-oral combination of serabelisib and sapanisertib. Serabelisib is a selective PI3K-alpha inhibitor, while sapanisertib is an mTORC1/mTORC2 inhibitor. The combination is designed to inhibit multiple nodes of the PI3K/AKT/mTOR pathway.
According to Faeth, the PI3K/AKT/mTOR pathway is dysregulated in up to 50% of all solid tumors, making it one of the most prevalent therapeutic targets in oncology. The company is investigating whether simultaneous targeting of multiple points in this pathway can support treatment activity in biomarker-selected cancer populations.
Fast Track Designation Covers a Previously Treated Patient Population
The FDA Fast Track designation applies specifically to patients with advanced or recurrent endometrial cancer whose tumors harbor a PI3K/AKT/mTOR pathway alteration and whose disease has previously been treated with both platinum-based chemotherapy and an immune checkpoint inhibitor.
Fast Track designation is intended to facilitate the development and review of drugs for serious conditions where there is an unmet medical need. The designation can provide opportunities for more frequent interaction with the FDA during development and may support expedited review processes when applicable.
Phase 2 Endometrial Cancer Study Expected to Report in 2026
Faeth is evaluating PIKTOR in Study FTH-PIK-201, a Phase 2 trial (NCT06463028) in second-line advanced endometrial cancer. The company expects to report topline data from the study by year-end 2026.
Faeth’s Chief Executive Officer, Anand Parikh, said the Fast Track designation reflects the unmet need in advanced endometrial cancer after progression despite platinum-based chemotherapy and an immune checkpoint inhibitor. The company also stated that preclinical data suggest PIKTOR may resensitize patients to chemotherapy.
PIKTOR Also Being Studied in Advanced Breast Cancer
In addition to the endometrial cancer program, PIKTOR is being evaluated in Study FTH-PIK-101, a Phase 1b/2 trial in patients with HR+/HER2- advanced breast cancer. The first patient was dosed in April 2026, and interim data are anticipated in 2027.
Next Steps in Clinical Development
The upcoming topline results from FTH-PIK-201 will provide an important clinical development milestone for PIKTOR in second-line advanced endometrial cancer. The ongoing breast cancer study will provide additional information on the investigational combination in another biomarker-defined oncology setting.
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About the Writer
Dishali Desai (LinkedIn) is a PharmD professional with expertise in clinical pharmacy, evidence-based healthcare writing, and published work on Brugada syndrome and ADR reporting.
Her interests include guideline integration, multimodal therapy, pharmacogenomics, and antibiogram utilization, with a focus on clinical evidence and treatment decisions.
As a healthcare writer, she translates complex clinical information into clear, accurate, and evidence-informed medical content.