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Scorpion Therapeutics Nominates STX-241 as Potentially Best-in-Class Fourth-Generation EGFR Inhibitor Development Candidate for the Treatment of Non-Small Cell Lung Cancer

— STX-241 is a highly selective, CNS-penetrant, fourth generation epidermal growth factor receptor (“EGFR”) inhibitor designed to address resistance to third generation EGFR inhibitors —

— Preclinical data to be presented in 2H 2023; investigational new drug (“IND”) application submission expected in 1H 2024 —

Third development candidate nominated since Scorpion’s founding three years ago, demonstrating the speed and quality of its Precision Oncology 2.0 strategy —

BOSTON, Mass. – April 3, 2023 – Scorpion Therapeutics, Inc. (“Scorpion”), a clinical-stage biotechnology company redefining the frontier of precision medicine through its Precision Oncology 2.0 strategy, today announced that it has named STX-241 as its next development candidate. STX-241 is the third development candidate nominated by Scorpion in less than three years, and the second highly selective epidermal growth factor receptor (“EGFR”) development candidate from the Company’s franchise of next-generation mutant EGFR inhibitors for the treatment of non-small cell lung cancer (“NSCLC”). STX-241 is an orally bioavailable, highly selective, central nervous system (“CNS”)-penetrant, and potentially best-in-class fourth generation EGFR tyrosine kinase inhibitor (“TKI”) designed to inhibit C797S mutations with a co-occurring EGFR exon 19 deletion or exon 21 mutation (“double mutant”) in NSCLC.

NSCLC is the most common form of lung cancer and EGFR mutations are one of its most common disease drivers. The current standard-of-care therapy for NSCLC patients with EGFR exon 19 or 21 mutations is osimertinib; however, up to 12.5 percent of treated patients, or approximately 3,000 people each year in the United States, acquire resistance mutations at C797S, for which there are currently no approved therapies1. As osimertinib use in first line EGFR-mutated NSCLC increases, mutations at C797S are expected to increase in parallel, creating a growing need for a fourth-generation EGFR TKI that can be used to treat this patient population.

“We are excited to name STX-241 as our next development candidate, as we believe it holds immense potential to improve the lives of a growing group of patients who invariably develop resistance to the standard-of-care,” said Axel Hoos, M.D., Ph.D., Chief Executive Officer of Scorpion Therapeutics. “We are particularly proud to introduce our third internally discovered development candidate in less than three years after the founding of Scorpion. This is a testament to the expertise of our scientific team, the capabilities of our platform, and the resulting speed and quality of our Precision Oncology 2.0 strategy. We look forward to sharing preclinical data for STX-241 later this year, and to submitting an IND application to the U.S. Food and Drug Administration (“FDA”) in the first half of 2024.”

Scorpion Therapeutics is developing STX-241 as an orally bioavailable, highly selective, potent inhibitor of double mutant NSCLC with the potential to deliver promising safety, tolerability, and efficacy, while exhibiting excellent CNS penetrance. In preclinical studies, STX-241 demonstrated potential best-in-class mutant vs. wild-type selectivity for the EGFR exon 19/C797S and EGFR exon 21/C797S double mutations when compared to key reference benchmarks, including approved first- and third-generation EGFR TKIs, gefitinib and osimertinib, which could translate into a wide therapeutic index. In addition, treatment with STX-241 demonstrated tumor regressions in animal models and favorable CNS penetration. Scorpion expects to present these data in the second half of 2023 and to submit an IND filing in the first half of 2024.

“Despite recent progress in the treatment of NSCLC, there is a need for new options that can address the resistance mutations that arise following front-line therapies,” said Darrin Stuart, Ph.D., Chief Scientific Officer of Scorpion Therapeutics. “While osimertinib has delivered tremendous benefit for people living with EGFR mutation driven NSCLC, we are hopeful that STX-241 can fill the treatment gap for the growing number of patients that develop ‘double mutant’ disease.”

STX-241 is the second highly selective EGFR product candidate to emerge from Scorpion’s franchise of next-generation mutant EGFR inhibitors for the treatment of NSCLC. Scorpion is also developing STX-721, a potentially best-in-class exon 20 mutant EGFR inhibitor, for which an IND application is expected in 2023.

About Scorpion Therapeutics

Scorpion is a pioneering oncology company redefining the frontier of precision medicine to deliver optimized and transformational therapies for larger populations of patients with cancer, a strategy Scorpion refers to as Precision Oncology 2.0. 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

Media Contact:
Ravi Moorthy
Scorpion Therapeutics

Investor Contact:
Hannah Deresiewicz
Stern Investor Relations, Inc.

1 Ramalingam S. (2022, August 6-9). Real-World Landscape of EGFR C797X Mutation as a Resistance Mechanism to Osimertinib in NSCLC. [Oral presentation]. 2022 World Conference on Lung Cancer, Vienna, Austria.