Serabelisib

Poster will characterize the efficacy of PIKTOR as a monotherapy and in combination with fulvestrant, oral SERDs, and CDK inhibitors in preclinical models of breast cancer Poster also includes results from head-to-head comparisons with gedatolisib, another multi-nodal inhibitor of the PI3K-AKT-mTOR (PAM) pathway, in preclinical breast cancer xenograft models The poster will be presented on Friday, October 23 at 15:15 CEST (9:15 a.m. ET). These preclinical data are intended to inform ongoing clinical development in the FTH-PIK-101 trial AUSTIN, Texas--(BUSINESS WIRE)--Faeth Therapeutics (Nasdaq: FTH), a clinical-stage oncology company developing multi-node therapies for cancer patients, including its lead program PIKTOR, today announced that it will present preclinical data at the European Society for Medical Oncology (ESMO) Congress 2026 in Madrid, Spain. The poster will be presented on Friday, October 23, and will showcase preclinical data intended to inform the ongoing development of PIKTOR in the FTH-PIK-101 Phase 1b/2 trial in HR+/HER2- breast cancer. In the poster, PIKTOR is tested as monotherapy and in combination with fulvestrant, oral SERDs and CDK inhibitors, which are standard and emerging treatments for patients with HR+ breast cancer. Data from mouse xenograft models will be accompanied by cellular assays showing that in these preclinical models, PIKTOR suppressed key signaling nodes in the PAM pathway, including AKT, at rates comparable to or exceeding those observed with tested single-node inhibitors. The poster also compares PIKTOR head-to-head with gedatolisib in two preclinical breast cancer xenograft models. A copy of the poster will be made available in the Investors section of Faeth’s website at the start of the poster session. Presentation Details: Title: Characterising the efficacy of multi-node PI3K/AKT/mTOR pathway inhibition with serabelisib and sapanisertib (PIKTOR) in combination with SERDs and CDK inhibitors in models of HR+/HER2- breast cancer Abstract Number: 431P Session: Basic Science Poster Session Date: Friday, October 23, 2026 Location: Poster Area - Hall 5 Time: 15:15 - 16:00 CEST (9:15 - 10:00 a.m. ET) Presenter: Oliver Maddocks, Ph.D., Co-Founder & Chief Scientific Officer of Faeth Therapeutics About PIKTOR PIKTOR is an investigational, proprietary, all-oral combination of serabelisib, a selective PI3K-alpha inhibitor, and sapanisertib, an mTORC1/mTORC2 inhibitor, designed to inhibit multiple nodes of the PI3K/AKT/mTOR pathway. This multi-node approach is designed to address the signaling feedback reactivation and treatment-emergent resistance mutations that may limit the efficacy of single-node PI3K/AKT/mTOR pathway inhibitors. According to published literature, the PAM pathway is dysregulated in up to 50% of all solid tumors, making it one of the most prevalent therapeutic targets in oncology. PIKTOR is being evaluated in a Phase 2 trial in second-line advanced endometrial cancer (Study FTH-PIK-201), with topline data anticipated by year-end 2026. PIKTOR is also being evaluated in a Phase 1b/2 trial in HR+/HER2- advanced breast cancer (Study FTH-PIK-101), in which the first patient was dosed in April 2026 and interim data is anticipated in 2027. About Faeth Therapeutics Faeth Therapeutics, Inc. (Nasdaq: FTH) is a clinical-stage biotechnology company focused on improving outcomes for cancer patients through multi-node inhibition of critical oncogenic pathways. The Company’s lead program is PIKTOR, an investigational all-oral combination of serabelisib and sapanisertib in development for endometrial and breast cancer. Faeth was co-founded in 2019 by Anand Parikh and Oliver Maddocks, Ph.D., together with scientific founders Lewis Cantley, Ph.D., the discoverer of the PI3K pathway; Siddhartha Mukherjee, M.D., D.Phil.; Karen Vousden, Ph.D.; Scott Lowe, Ph.D.; and Greg Hannon, Ph.D. The Company intends to use its website as a means of disclosing material non-public information and for complying with its disclosure obligations under Regulation FD. For more information, please visit and follow the Company on LinkedIn. Cautionary Note Regarding Forward-Looking Statements This press release contains “forward-looking statements” within the meaning of the federal securities laws, including the safe harbor provisions of the Private Securities Litigation Reform Act of 1995. Forward-looking statements include all statements that are not historical facts and may be identified by words such as “anticipate,” “believe,” “expect,” “intend,” “plan,” “may,” “will,” “would,” “could,” “should,” “estimate,” “potential,” “target,” “on track” and similar expressions, although not all forward-looking statements contain these words. These statements include, but are not limited to, statements regarding: the content, timing and presentation of data at the ESMO Congress 2026, including head-to-head comparisons with gedatolisib; the Company’s interpretation of preclinical data and the conclusions the Company draws from that data; the Company’s expectations regarding its pipeline and development plans, including the Phase 2 trial of PIKTOR in advanced endometrial cancer and the anticipated timing of topline data, and the Phase 1b/2 trial of PIKTOR in HR+/HER2- advanced breast cancer and the anticipated timing of interim data; and the potential therapeutic benefits, tolerability pro differentiation of PIKTOR. Forward-looking statements are based on management’s current expectations and assumptions and are subject to a number of risks and uncertainties, many of which are beyond the Company’s control, that could cause actual results to differ materially from those expressed or implied. These risks and uncertainties include, among others, risks related to clinical development and the conduct, timing and results of clinical trials; the risk that results from preclinical studies, including comparisons with other product candidates or approved products, may not be predictive of results in ongoing or future clinical trials; the Company’s need for additional financing; its limited operating history and history of operating losses; risks related to the integration of Faeth; the Company’s ability to satisfy applicable Nasdaq listing requirements and to maintain the listing of its common stock; and the other risks and uncertainties described under the headings “Risk Factors” and “Summary of Risk Factors” in the Company’s Annual Report on Form 10-K filed with the Securities and Exchange Commission (the “SEC”) on March 30, 2026, its Quarterly Report on Form 10-Q filed with the SEC on August 4, 2026, and its definitive proxy statement filed with the SEC on April 27, 2026, as well as in the Company’s subsequent filings. Forward-looking statements speak only as of the date of this press release, and the Company undertakes no obligation to update any forward-looking statement, except as required by law. Contacts Investor Contact: Matthew Biegler, SVP, Investor Relations matt@faeththerapeutics.com Media Contact: Patrick Schmidt, Consort Partners faeththerapeutics@consortpartners.com