PFL-241/STX-241 is a highly selective, and potentially best-in-class fourth generation epidermal growth factor receptor (“EGFR”) inhibitor

One of two EGFR programs being developed with Scorpion Therapeutics

Pierre Fabre Laboratories, a global player in oncology, and Scorpion Therapeutics, Inc. (“Scorpion”), a pioneering clinical-stage oncology company dedicated to transforming the lives of cancer patients by redefining the frontier of precision medicine, today announced that the first patient has been dosed in a Phase I/II, first-in-human dose-escalation, dose-optimization and dose-expansion trial. This clinical trial evaluates PFL-241/STX-241, a highly differentiated, orally bioavailable, highly selective tyrosine kinase inhibitor ("TKI") targeting epidermal growth factor receptor ("EGFR") Exon 19 or 21 mutations with the co-occurring C797S mutation, a known resistance mechanism to 3^rd generation EGFR inhibitors.

The PFL-241/STX-241 Phase I/II trial is an open label, multi-center study that aims to assess the safety, tolerability, pharmacokinetics (PK), pharmacodynamics (PD) and preliminary clinical efficacy of PFL-241/STX-241 as a monotherapy in patients with locally advanced or metastatic non-small cell lung cancer (“NSCLC”) harboring EGFR Exon 19 or 21 mutations with the co-occurring C797S mutation.

NSCLC is the most common form of lung cancer and EGFR mutations are one of its most common disease drivers, occurring in up to 38 percent of tumors, depending on geography^1,2,3.

“We are eager to begin the clinical evaluation of PFL-241/STX-241, our mutant-selective 4^th generation EGFR inhibitor, a molecule with differentiated properties that we believe has the potential to become a best-in-class therapeutic option for patients developing resistance to current targeted therapy,” said Francesco Hofmann, Head of Research and Development for Medical Care at Pierre Fabre Laboratories. “The initiation of this clinical trial highlights our team’s engagement and execution in strong partnership with Scorpion Therapeutics, and we look forward to demonstrating how patients could potentially benefit from this targeted therapy.”

PFL-241/STX-241 is an oral treatment designed to selectively inhibit the C797S resistance mutation co-occurring with EGFR exon 19 deletion or exon 21 mutation (“double mutant”). Those “double mutants” are emerging as an on-target resistance mechanism in a subset of NSCLC patients. Most recent data suggest that the C797S mutation emerges in approximately 12.5%^4-8 of patients undergoing therapy with 3^rd generation EGFR inhibitors. There are currently no approved therapeutic options for patients who develop this “double mutant” EGFR NSCLC.

“The initiation of the second clinical trial in partnership with Pierre Fabre Laboratories is an important milestone as we work together to enable the rapid, global advancement of our next-generation EGFR inhibitors for difficult-to-treat NSCLC patients,” said Mark Chao, M.D., Ph.D., Chief Medical Officer of Scorpion. “PFL-241/STX-241 is a novel, CNS-penetrant and highly potent and selective treatment option for patients who develop ‘double mutant’ disease for which there is currently no approved treatment, and it’s a pleasure to partner with Pierre Fabre Laboratories, a company who shares our commitment to bringing innovative treatments to this underserved patient population. We look forward to demonstrating how PFL-241/STX-241’s differentiated preclinical profile translates into clinical benefit for patients.”

About Pierre Fabre Laboratories R&D pipeline

Pierre Fabre Laboratories has expanded its efforts in precision oncology by adding several assets to its R&D pipeline. In partnership with Scorpion Therapeutics, PFL-241/STX-241 and PFL-721/STX-721, two mutant-selective EGFR inhibitors, will be developed for the treatment of EGFR-driven non-small cell lung cancer (NSCLC) patients. Through the acquisition of Vertical Bio, PFL-002/VERT-002 will undergo clinical testing in solid tumours driven by MET genetic alterations. More recently, the pan-RAF inhibitor exarafenib was acquired from Kinnate Biopharma with the aim to expand targeted therapy options for RAS/RAF-driven solid tumours. These new additions to its clinical development portfolio complement Pierre Fabre Laboratories’ existing precision oncology portfolio targeting BRAF, MEK, HER2, with encorafenib, binimetinib and neratinib, respectively.

About Pierre Fabre Laboratories

Pierre Fabre Laboratories is one of Europe's leading pharmaceutical companies. For over 40 years, it has established itself as an international player in oncology, mastering the entire value chain from R&D to marketing. Its portfolio of oncology specialties covers colorectal, breast, lung and skin cancers, as well as certain hematologic malignancies and precancerous dermatological conditions such as actinic keratosis. In 2023, its oncology revenue amounted to nearly 500 million euros, over 90% of which was generated outside France.

In 2023, Pierre Fabre Laboratories posted 2.83 billion euros in revenue, 70% of which came from international sales in 120 countries. Its portfolio includes several international brands and medical franchises such as Pierre Fabre Oncologie, Pierre Fabre Dermatologie, Pierre Fabre Pharma Care, Eau Thermale Avène, Ducray, A-Derma, Klorane, René Furterer and Même Cosmetics.

Historically based in the southwest of France and manufacturing 95% of its products in France, Pierre Fabre Laboratories employs over 10 000 people worldwide. Its annual R&D budget amounts to nearly 200 million euros, of which about 50% is dedicated to targeted therapies in oncology and 40% to skin health and care solutions.

Pierre Fabre Laboratories' majority shareholder (86%) is the eponymous Foundation, which is recognized by the French government as being a public–interest foundation. This capital structure guarantees the company's independence and long-term vision. Dividends paid to the Pierre Fabre Foundation enable it to design and finance healthcare-access programs in developing countries. Employees are the company's secondary shareholder, through an international employee shareholding plan.

Pierre Fabre Laboratories’ sustainability policy has been assessed by the independent AFNOR Certification body and has been awarded the "Exemplary" level of its CSR label (ISO 26 000 standard for sustainable development).

For more information, visit www.pierre-fabre.com, @PierreFabreGroup

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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