Scorpion Therapeutics, Inc. (“Scorpion”), a pioneering clinical-stage oncology company dedicated to transforming the lives of cancer patients by redefining the frontier of precision oncology, today announced that it was selected to present initial, first-in-human clinical results from the Phase 1/2 study of STX-478, a mutant-selective PI3Kα inhibitor, in advanced solid tumor patients in a Proffered Paper late-breaking session at the European Society for Medical Oncology (“ESMO”) Congress 2024, taking place September 13 – 17, 2024 in Barcelona, Spain.

“The presentation of first-in-human clinical data for our lead candidate, STX-478, marks an important milestone for patients living with advanced solid tumors driven by PI3Kα mutations, especially HR+/HER2- breast cancer, and for Scorpion as we work to broaden the reach and impact of precision oncology for patients with high unmet medical need,” said Mark Chao, M.D., Ph.D., Chief Medical Officer of Scorpion. “While PI3Kα has been one of the highest profile targets in cancer for years, current treatment options suffer from toxicity limitations and subpar efficacy due to a lack of mutant selectivity. These initial data will provide early insight into how STX-478's differentiated profile translates to potentially superior outcomes in PI3Kα-mutated cancers, and we look forward to presenting initial assessments of safety, pharmacokinetic and pharmacodynamic data and preliminary efficacy data at the ESMO 2024 Congress."

Details of the Proffered Paper presentation are as follows:

Title: First-in-human Results of STX-478, a Mutant-selective PI3Kα Inhibitor, in Advanced Solid Tumor Patients

Presentation Number: LBA27

Session Name: Proffered paper session 2: Developmental therapeutics (ID 156)

Session Date & Time: Sunday, September 15, 2024, at 14:45 CEST – 16:15 CEST (8:45 a.m. – 10:15 a.m. ET)

Presentation Time: 14:55 CEST – 15:05 CEST (8:55 a.m. – 9:05 a.m. ET)

Location: Salamanca Auditorium - Hall 5

Presenter: Alberto J. Montero, M.D. (University Hospitals Cleveland, OH, USA)

According to ESMO, the late-breaking abstract will be published via the ESMO website at 00:05 CEST on September 15 (6:05 p.m. ET on September 14). Data presented at the conference will be available to view in the "Publications & Presentations" section of the Scorpion website (https://www.scorpiontx.com/publications-posters/) following the ESMO 2024 Congress.

About STX-478

STX-478 was designed to improve outcomes in patients harboring PI3Kα mutations, one of the most prevalent drivers of cancer, occurring in over 166,000 patients per year with breast, gynecological and other solid tumors in the United States alone. In preclinical models, STX-478 demonstrated robust activity across a range of PI3Kα mutations while sparing wild-type PI3Kα inhibition in normal tissues; previous generations of non-selective PI3Kα inhibitors have limited patient benefit due to these on-target toxicities. Scorpion’s Phase 1/2 clinical trial is a multi-center, global, open-label study designed to evaluate the safety and tolerability of STX-478 in multiple ascending doses for patients with locally advanced or metastatic HR+/HER2- breast cancer and other solid tumors driven by PI3Kα mutations. The program entered the clinic in 2023 and has rapidly advanced, now in multiple expansion cohorts across a range of solid tumors and in breast cancer as monotherapy and in combinations with fulvestrant and CDK4/6 inhibitors. To learn more about the first-in-human trial of STX-478, please visit this page.

About Scorpion Therapeutics

Scorpion is a pioneering clinical-stage oncology company redefining the frontier of precision medicine to deliver optimized and transformational therapies for larger populations of patients with cancer. Scorpion has built a proprietary and fully-integrated platform of the most advanced technologies across cancer biology, medicinal chemistry, and data sciences, with the goal of consistently and rapidly creating exquisitely selective small molecule compounds against an unprecedented spectrum of targets. Scorpion aims to leverage its platform to advance a broad pipeline of wholly-owned, optimized compounds across three target categories: best-in-class molecules targeting validated oncogene targets; first-in-class molecules for previously undruggable targets; and first-in-class molecules for novel cancer targets. For more information, visit www.scorpiontx.com.

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