Austin, Texas — August 17, 2026
Faeth Therapeutics announced that the U.S. Food and Drug Administration (FDA) has granted Fast Track designation to its investigational PIKTOR combination of sapanisertib and serabelisib with paclitaxel for patients with advanced or recurrent endometrial cancer whose tumors harbor alterations in the PI3K/AKT/mTOR pathway. The designation applies to patients previously treated with platinum-based chemotherapy and an immune checkpoint inhibitor. The FDA Fast Track decision represents an important regulatory milestone for Faeth’s lead oncology program and supports the company’s efforts to advance a targeted treatment strategy for patients with advanced endometrial cancer who have limited therapeutic options following prior treatment. Faeth expects to report topline results from its ongoing Phase 2 FTH-PIK-201 study by the end of 2026.
FDA Fast Track Highlights Unmet Need in Endometrial Cancer
The Fast Track designation is focused on a patient population with significant unmet medical needs, particularly individuals whose advanced or recurrent endometrial cancer has progressed after platinum-based chemotherapy and immune checkpoint inhibitor treatment. Faeth is developing PIKTOR as a multi-node approach to the PI3K/AKT/mTOR pathway, a signaling network frequently implicated in cancer development and progression. The company believes simultaneously targeting multiple components of this pathway could potentially address mechanisms associated with tumor growth and treatment resistance. Importantly, the FDA designation does not establish that PIKTOR is effective or safe; it is a regulatory designation intended to facilitate development and review of therapies addressing serious conditions with unmet medical needs. The upcoming clinical data will therefore be important in determining whether the investigational combination can demonstrate meaningful clinical benefit in biomarker-selected patients.
PIKTOR Advances Toward Phase 2 Data
PIKTOR is an investigational, all-oral combination of serabelisib and sapanisertib, designed to inhibit multiple nodes of the PI3K/AKT/mTOR signaling pathway. Serabelisib is a selective PI3K-alpha inhibitor, while sapanisertib is designed to inhibit mTORC1 and mTORC2. The combination is being evaluated in the ongoing Phase 2 FTH-PIK-201 trial in patients with second-line advanced endometrial cancer. Faeth expects topline results from this study by year-end 2026, providing an important clinical readout for the program. The company has also advanced PIKTOR into a separate Phase 1b/2 study in HR-positive/HER2-negative advanced breast cancer, where additional clinical data are expected at a later stage. These studies are intended to assess the potential of multi-node pathway inhibition across different cancer settings.
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Faeth Builds Multi-Node Oncology Strategy
The FDA Fast Track designation strengthens Faeth Therapeutics’ development strategy around PIKTOR, its lead oncology program. The company is focused on developing therapies that simultaneously inhibit multiple nodes within critical oncogenic pathways rather than relying on inhibition of a single target. The PI3K/AKT/mTOR pathway is considered an important signaling network in oncology and has been implicated across numerous solid tumors. For Faeth, the current development strategy centers on identifying patients through biomarker selection and evaluating whether PIKTOR can improve treatment outcomes in specific molecularly defined populations. The combination with paclitaxel in advanced endometrial cancer is intended to investigate whether pathway inhibition can potentially enhance sensitivity to chemotherapy. However, PIKTOR remains investigational, and its clinical effectiveness and long-term safety have not yet been established. The anticipated Phase 2 topline results will be a key milestone for the program.
Source: Faeth Therapeutics press relese
