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Scorpion Therapeutics and Pierre Fabre Laboratories Announce First Patient Dosed in Phase 1/2 Clinical Trial of STX-721, a Mutant-Selective EGFR Exon 20 Inhibitor for the Treatment of Locally Advanced or Metastatic Non-Small Cell Lung Cancer

STX-721 is characterized by high selectivity and a potentially best-in-class profile
Scorpion’s second program to enter clinical development this year

One of two EGFR programs being developed with Pierre Fabre Laboratories

Scorpion Therapeutics, Inc. (“Scorpion”), a pioneering clinical-stage oncology company redefining the frontier of precision medicine through its Precision Oncology 2.0 strategy, and Pierre Fabre Laboratories today announced that the first patient has been dosed in a Phase 1/2 first-in-human dose escalation and expansion clinical trial evaluating STX-721, Scorpion’s highly differentiated, orally bioavailable, irreversible highly selective tyrosine kinase inhibitor (“TKI”) targeting epidermal growth factor receptor (“EGFR”) and ERBB2 (HER2) Exon 20 insertion (“ex20ins”) mutations, well-known, clinically validated oncogenic drivers in non-small cell lung cancer (“NSCLC”). The Phase 1/2 clinical trial will evaluate STX-721 as a monotherapy in participants with locally advanced or metastatic NSCLC harboring EGFR ex20ins mutations.

NSCLC is the most common sub-type of lung cancer and various EGFR mutations are the most frequent drivers of NSCLC, occurring in up to 38% of tumors, depending on geography.[i],[ii],[iii] Of this population, up to 10% have ex20ins mutations.[iv]

“We are excited to begin the clinical evaluation of STX-721, our mutant-selective EGFR ex20ins inhibitor with a potentially best-in-class profile, for the treatment of non-small cell lung cancer,” said Axel Hoos, M.D., Ph.D., Chief Executive Officer of Scorpion. “The initiation of our second clinical trial this year underscores our team’s productivity and execution, as well as the confidence that Scorpion and Pierre Fabre Laboratories have in the quality, selectivity, and potential clinical differentiation of this compound. Based on preclinical data to-date, we believe that STX-721 is more selective and can provide a wider therapeutic window than other therapies currently on the market or in development and, as a result, has the potential to deliver superior efficacy to this highly underserved patient population.”

“We are pleased to see STX-721 enter the clinic, and the overall progress we’ve achieved since we announced the partnership with Scorpion six months ago,” said Eric Ducournau, Chief Executive Officer of Pierre Fabre Laboratories. “Our two teams have been working closely on both of the EGFR candidates and we look forward to seeing how patients may benefit from this targeted therapy.”

STX-721 is an oral treatment designed to be mutant-selective and optimized for tolerability and efficacy when compared to currently available commercial treatments. Existing therapeutic options face significant limitations that are associated with the inhibition of wild-type EGFR in healthy tissues, including serious adverse events often leading to dose reductions or interruptions. “STX-721 is a wild-type-sparing, oral inhibitor of EGFR ex20ins mutations with a compelling preclinical selectivity profile,” said Michael Streit, M.D., Chief Medical Officer of Scorpion. “In this Phase 1/2 trial, we will aim to demonstrate how these unique qualities translate into a potentially best-in-class product profile that increases response rates as a result of its optimized design. We look forward to partnering with study investigators, as well as our colleagues at Pierre Fabre Laboratories, to evaluate STX-721 in patients with EGFR ex20ins-mutated NSCLC.”

About STX-721 Phase 1/2 Trial

Scorpion’s Phase 1/2 clinical trial, in collaboration with Pierre Fabre Laboratories, is a multi-center, open-label study designed to evaluate the safety and tolerability of STX-721 in multiple ascending doses for patients with locally advanced or metastatic NSCLC driven by EGFR mutations. The goal of the trial is to characterize the safety profile of STX-721 and determine a maximum tolerated dose or a lower optimal-biologically active dose, if appropriate, as the recommended Phase 2 dose (“RP2D”) as a monotherapy for NSCLC driven by EGFR exon20ins mutations. Once the RP2D is established, Scorpion intends to continue to evaluate the safety, tolerability and overall efficacy of STX-721. Secondary objectives for this Phase 1/2 trial include assessing the pharmacokinetic profile, pharmacodynamic effects and clinical response as measured by Response Evaluation Criteria In Solid Tumors (“RECIST”) version 1.1. To learn more about the first-in-human trial of STX-721, 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, 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

About Pierre Fabre Laboratories

Pierre Fabre Laboratories is a leading French medical and beauty care company with over 4 decades of experience in innovation, development, manufacturing, and commercialization in oncology. The company dedicated about 80% of its R&D spendings to oncology in 2022 and has declared targeted therapies as its main R&D priority. Its current commercial portfolio in oncology covers colorectal, breast and lung cancers, melanoma, hematology, and pre-cancerous skin conditions like actinic keratosis.

In 2022, Pierre Fabre Laboratories posted 2.7 billion euros in revenues, 69% of which came from international sales in 120 countries. Established in the South-West of France since its creation in 1962, the Group manufactures over 90% of its products in France and employs some 9,600 people worldwide. The company is 86%-owned by the Pierre Fabre Foundation, a government-recognized public-interest foundation, and secondarily by its own employees through an international employee stock ownership plan. Pierre Fabre Laboratories’ sustainability policy has been assessed by the independent AFNOR Certification body at the “Exemplary” level of its CSR label (ISO 26 000 standard for sustainable development).

Further information about Pierre Fabre Laboratories can be found at, @PierreFabre.

For Scorpion Therapeutics:

Media Contact:
Ravi Moorthy
Scorpion Therapeutics, Inc.

Investor Contact:
Hannah Deresiewicz
Stern Investor Relations, Inc.

For Pierre Fabre Laboratories:

Media Contact:
Laure Sgandurra
+33 6 32 54 92 01
Pierre Fabre Laboratories

[i] The Prevalence of EGFR Mutation in Patients with Non-Small Cell Lung Cancer, Oncotarget, October 2016

[ii] EGFR Mutation Incidence in Non-Small Cell Lung Cancer, J Cancer Res., August 2015

[iii] Molecular Epidemiology of EGFR Mutations in Asian Patients, PLoS ONE, November 2015

[iv] EGFR exon 20 insertion mutations in advanced non-small-cell lung cancer: current status and perspectives, Biomarker Research, April 2022