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Scorpion Therapeutics Nominates STX-721 as EGFR-EXON-20 Development Candidate with a Best-in-Class Profile

— STX-721 is a next-generation, highly selective Exon 20 mutant EGFR inhibitor designed for a best-in-class profile to overcome efficacy and toxicity limitations of currently available agents —

— Approximately 3,400 patients per year diagnosed with NSCLC tumors that express EGFR with Exon 20 insertion mutations in the United States–

— Preclinical data to be presented in 2H 2022; investigational new drug (“IND”) application submission expected in 2023 —

BOSTON, Mass. – June 29, 2022 – Scorpion Therapeutics, Inc. (“Scorpion Therapeutics”), a pioneering biotechnology company redefining the frontier of precision medicine through its Precision Oncology 2.0 strategy, today announced that it has selected STX-721 as a development candidate from its STX-EGFR-EXON20 program. STX-721 is a next-generation, orally delivered small molecule designed with potentially best-in-class selectivity to target Exon 20 insertion mutations in epidermal growth factor receptors (“EGFR”), a well-known, clinically validated oncogenic driver in non-small cell lung cancer (“NSCLC”).

NSCLC is the most common form of lung cancer and EGFR mutations are one of the most common mutations in NSCLC. NSCLC tumors that express EGFR with Exon 20 insertion mutations have an incidence of approximately 3,400 patients per year in the United States. Commercially available therapies for NSCLC patients with EGFR Exon 20 insertion mutations have moderate clinical efficacy and are limited by significant toxicities associated with the inhibition of wild-type EGFR in healthy tissues such as the skin and GI tract. These toxicities can lead to dose reductions or interruptions, which may reduce efficacy and leave a significant unmet need.

“We are delighted to announce STX-721 as our second clinical program,” said Axel Hoos, M.D., Ph.D., Chief Executive Officer of Scorpion Therapeutics. “While currently marketed agents have transformed the treatment of many EGFR-mutant lung cancers, patients presenting with Exon 20 insertion mutations remain underserved by existing options, which lack sufficient selectivity over wild-type EGFR and therefore carry significant, dose-limiting toxicities that narrow the therapeutic window and attenuate their efficacy. STX-721 was designed as a next-generation molecule to overcome these limitations. We look forward to sharing the detailed preclinical profile for STX-721 later this year and to submitting an IND to the U.S. Food and Drug Administration in 2023.”

Leveraging its proprietary drug-hunting platform, Scorpion Therapeutics designed a highly differentiated candidate molecule that provides exquisitely selective inhibition of Exon 20 insertion mutations compared to the wild-type form of the protein. This may allow for maximal inhibition of the mutant protein in cancer cells compared to normal tissues, thereby reducing the toxicities that lead to dose limitations or reductions with existing EGFR Exon 20 inhibitors. In preclinical studies, STX-721 demonstrated best-in-class selectivity versus all other disclosed clinical-phase Exon 20 inhibitors, as well as dose-dependent anti-tumor activity in xenograft models at well-tolerated doses. Scorpion Therapeutics expects to present these preclinical data at a medical meeting in the second half of 2022 and to submit an IND for STX-721 in 2023.

About Scorpion Therapeutics

Scorpion Therapeutics 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 Therapeutics refers to as Precision Oncology 2.0. Scorpion Therapeutics 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 Therapeutics 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.