Sermonix Pharmaceuticals Announces Chinese IND Approval for Lasofoxifene

Sermonix Pharmaceuticals LLC, a biopharmaceutical firm specializing in innovative treatments for metastatic breast cancers (mBC), has announced a significant development. The National Medical Products Administration (NMPA) of China has approved the investigational new drug (IND) application for oral lasofoxifene, also known as HLX78 in China, submitted by Sermonix's Chinese partner, Shanghai Henlius Biotech, Inc.

This IND approval authorizes Henlius to participate in the global registrational ELAINE-3 trial within China. The ELAINE-3 trial (NCT05696626), which is the third Evaluation of Lasofoxifene in ESR1 Mutations (ELAINE) study, is designed to compare the efficacy of oral lasofoxifene combined with Eli Lilly’s CDK4/6 inhibitor abemaciclib (Verzenio®) against the combination of fulvestrant and abemaciclib. The trial will involve 400 pre- and post-menopausal women with locally advanced or metastatic ER+/HER2- breast cancer that includes an ESR1 mutation.

In January, under a strategic collaboration agreement, Henlius obtained exclusive rights from Sermonix to develop, manufacture, and commercialize oral lasofoxifene in China. Recently, Henlius expanded its license to include additional territories in Asia, with accompanying upfront, milestone, and royalty payments. This agreement also facilitates collaborative development efforts in Japan, where Sermonix has already completed a Phase 1 Japanese pharmacokinetic study. Both companies will now engage with Japan's Pharmaceuticals and Medical Devices Agency (PMDA) to establish a regulatory pathway for lasofoxifene.

Dr. David Portman, the founder and CEO of Sermonix, expressed satisfaction with Henlius's progress, noting that the IND approval in China will enable the enrollment of Chinese patients into the ELAINE-3 trial. This expansion will diversify the patient population and potentially offer new hope for those battling advanced breast cancer.

Ms. Ping Cao, Chief Business Development Officer at Henlius, highlighted the rapid progress of the collaboration since its inception in January 2024. She emphasized the team's unified dedication and efficient execution, which has culminated in the recent IND approval in China.

Oral lasofoxifene is a targeted endocrine therapy currently in clinical development. It has shown strong engagement with ESR1 antagonists in breast tissue, particularly in cases involving ESR1 mutations. In the ELAINE-1 and ELAINE-2 Phase 2 clinical studies, lasofoxifene demonstrated notable anti-tumor activity both as a standalone treatment and when combined with abemaciclib. The therapy's bioavailability and efficacy in addressing estrogen receptor mutations, along with its potential benefits for sexual and urogenital health, suggest it could be a valuable treatment for patients who have developed endocrine resistance due to ESR1 mutations, pending approval.

Breast cancer remains the second most diagnosed cancer globally, with approximately 2.3 million new cases reported in 2022, including over 357,000 in China. Estrogen receptor-positive (ER+) breast cancer accounts for 60-70% of all breast cancer cases. Endocrine therapy is a primary treatment strategy for ER+ breast cancer, with aromatase inhibitors (AIs) being the most commonly used. However, resistance to AIs often develops in advanced-stage patients, with ESR1 mutations being a significant cause, present in up to 40% of cases. This creates a substantial clinical need for new treatment options for ER+/HER2- breast cancer.

Oral lasofoxifene, if successfully developed and approved, could address this unmet need, providing a new therapeutic option for patients with ESR1-mutated breast cancer.