LONDON, May 22, 2026
Ellipses Pharma and Sichuan Kelun-Biotech Biopharmaceutical Co., Ltd. announced that pivotal Phase 2 clinical trial data for EP0031/A400 (lunbotinib), a next-generation selective RET inhibitor (SRI), will be presented during an oral session at the 2026 American Society of Clinical Oncology (ASCO) Annual Meeting in Chicago from May 29 to June 2. The presentation highlights promising efficacy and safety findings in patients with RET fusion-positive advanced non-small cell lung cancer (NSCLC), further strengthening the global development profile of the investigational targeted therapy.
Strong Efficacy Signals in RET-Positive NSCLC
The oral presentation will feature results from Kelun-Biotech’s pivotal Phase 2 clinical trial NCT05265091, which evaluated EP0031/A400 at 90 mg once daily in both treatment-naïve and previously treated patients with locally advanced or metastatic RET fusion-positive NSCLC. According to the companies, the investigational therapy demonstrated robust anti-tumor activity across both patient populations, along with a manageable and encouraging safety profile.
The study results are especially significant because RET-driven lung cancers remain a relatively rare but aggressive subtype of NSCLC, accounting for approximately 1–2% of lung cancer cases. Although first-generation RET inhibitors have improved treatment outcomes, many patients eventually develop resistance mutations, creating an urgent need for more potent next-generation therapies capable of overcoming acquired resistance and improving central nervous system (CNS) penetration.
EP0031/A400 was specifically engineered to target a broad range of RET alterations and resistance mutations. Preclinical studies demonstrated greater potency, stronger tumor inhibition, and improved CNS exposure compared with earlier-generation RET inhibitors. The therapy also showed promising activity in patients previously treated with first-generation selective RET inhibitors, including evidence of intracranial responses.
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Global Development Expands Beyond China
In September 2025, Kelun-Biotech submitted a New Drug Application (NDA) to China’s National Medical Products Administration (NMPA) for EP0031/A400 in RET fusion-positive advanced NSCLC, and the application was accepted for regulatory review. Outside Greater China and selected Asian territories, the drug is being developed by Ellipses Pharma under the name EP0031 through an exclusive licensing agreement between the two companies.
Ellipses is currently conducting the ongoing global Phase 1/2 EP0031-101 trial (NCT05443126) across the United States, Europe, United Kingdom, and United Arab Emirates. The study is evaluating EP0031 both as monotherapy and in combination with platinum-doublet chemotherapy in RET-positive NSCLC patients who are either naïve to or previously treated with first-generation RET inhibitors. The companies believe combination approaches may further improve treatment durability and overcome resistance mechanisms observed with current therapies.
Professor Sir Christopher Evans, Chairman of Ellipses Pharma, described the ASCO presentation as a major milestone for the program, emphasizing the company’s commitment to bringing the therapy to patients globally as quickly as possible. Professor Tobias Arkenau, Global Head of Drug Development and Chief Medical Officer at Ellipses Pharma, added that the ASCO data reinforce the potential of EP0031/A400 as a promising next-generation selective RET inhibitor for Western and global markets.
Next-Generation RET Inhibitor Targets Unmet Need
EP0031/A400 has already received Orphan Drug Designation from the U.S. FDA for RET fusion-positive tumors, highlighting its potential importance in precision oncology. The therapy is designed to address one of the key limitations of first-generation RET inhibitors — acquired resistance caused by secondary RET mutations and inadequate CNS penetration.
RET alterations are recognized oncogenic drivers across multiple tumor types, including NSCLC and thyroid cancer. As precision medicine continues to reshape lung cancer treatment, next-generation targeted therapies such as EP0031/A400 are expected to play a growing role in extending survival and improving outcomes for patients with molecularly defined cancers. With pivotal clinical data now moving into global spotlight at ASCO 2026, EP0031/A400 is emerging as one of the more closely watched next-generation RET-targeted therapies in oncology development.
Source: Ellipses Pharma, press release
