Faeth Therapeutics Gains FDA Fast Track Status Ahead of Phase 2 Endometrial Cancer Readout

PIKTOR is designed to inhibit multiple points in a cancer-driving pathway, with topline data expected by year-end.

Faeth Therapeutics (Nasdaq: FTH) has received FDA Fast Track designation for PIKTOR in combination with paclitaxel for a biomarker-selected group of patients with advanced or recurrent endometrial cancer.

The designation covers patients whose tumors have an alteration in the PI3K/AKT/mTOR pathway and whose disease has already been treated with platinum-based chemotherapy and an immune checkpoint inhibitor.

For Faeth, the regulatory designation comes ahead of a more consequential milestone: topline data from its ongoing Phase 2 trial in second-line advanced endometrial cancer, expected by year-end 2026.

Targeting More Than One Point in the Pathway

PIKTOR combines two oral investigational drugs: serabelisib, a selective PI3K-alpha inhibitor, and sapanisertib, an mTORC1/mTORC2 inhibitor.

The idea is to inhibit multiple nodes of the PI3K/AKT/mTOR pathway rather than target a single point. The pathway plays an important role in cell growth and survival and, according to published literature cited by Faeth, is dysregulated in up to 50% of solid tumors.

Faeth is testing PIKTOR with paclitaxel based in part on preclinical findings suggesting the combination may resensitize tumors to chemotherapy. Whether that translates into meaningful clinical benefit is one of the questions the Phase 2 study is designed to address.

A Defined Patient Population

The Fast Track designation is specifically tied to biomarker-selected patients whose cancers harbor a PI3K/AKT/mTOR pathway alteration and have progressed following prior platinum chemotherapy and immunotherapy.

Fast Track is intended to facilitate the development and review of drugs addressing serious conditions and unmet medical needs. It can provide more frequent interaction with the FDA and, if applicable requirements are met, potential eligibility for rolling review, priority review or accelerated approval. The designation itself does not establish that a therapy is effective or guarantee approval.

That distinction matters here because PIKTOR remains in clinical development.

The upcoming Phase 2 data should provide a clearer look at the combination’s efficacy and safety in this patient population. Lucid Capital Markets, which maintains a Buy rating and $50 price target on Faeth, described the readout as an important opportunity to assess PIKTOR’s preliminary efficacy, safety and ability to combine with chemotherapy. The firm also sees potential readthrough to the program in breast cancer.

Beyond Endometrial Cancer

Faeth is separately evaluating PIKTOR in a Phase 1b/2 study in HR-positive/HER2-negative advanced breast cancer. The first patient was dosed in April, with interim data anticipated in 2027.

That makes endometrial cancer the nearer-term clinical test of a broader strategy.

For now, Fast Track gives Faeth an additional regulatory mechanism for engaging with the FDA as PIKTOR advances. The more important evidence comes next: the Phase 2 data expected by the end of the year.