HONG KONG – Rapt Therapeutics Inc., of San Francisco, and Seoul, South Korea-based Hanmi Pharmaceutical Co. Ltd. entered a license agreement for Rapt’s FLX-475 in Asia. FLX-475 is an oral, small-molecule CCR4 antagonist for cancer treatment. 

Under the agreement, Rapt will receive $10 million in an up-front payment and near-term milestone payment. Also, the U.S. company will be granted up to $48 million in development milestones and up to $60 million in potential sales milestones. Rapt is eligible to receive double-digit royalties on future sales of FLX-475 in Korea and China, including Taiwan and Hong Kong.

Hanmi will jointly develop FLX-475 with Rapt, and it secures the exclusive rights of commercialization in the specified regions. The Korean company will conduct a phase II trial in Korea and China to assess FLX-475 in gastric cancer next year.

“We don’t have a pipeline or an R&D history that exactly matches the function of FLX-475,” a spokeswoman at Hanmi told BioWorld. “However, we have decided to introduce the compound due to its great potential value in terms of cancer treatment and global marketing.”

“This compound complements our current product portfolio and has the potential to address a large and growing population of patients suffering from cancers that are prevalent in Asian countries,” said Hanmi CEO Se-chang Kwon We. “We look forward to partnering with Rapt to advance FLX-475 through the clinical process efficiently.”  

FLX-475 is designed to block the migration of regulatory T cells (Tregs) into tumors but not healthy tissues. Treg represents a dominant pathway for down-regulating the immune response, and it may limit the effectiveness of existing therapies such as checkpoint inhibitors.

Rapt is developing FLX-475 for the treatment of a broad range of “charged” tumors, which represent cancer types most likely to respond to the compound. According to the company, blocking the Treg migration to the tumor may restore naturally occurring antitumor immunity and synergize with various conventional and immune-based therapies such as radiation, chemotherapy, checkpoint inhibitors, immune stimulators and adoptive T-cell therapy.

“FLX-475 targets ‘charged’ tumors, including virally associated cancers, gastric cancer, non-small-cell lung cancer, triple-negative breast cancer, and head and neck cancers, which are predicted to have high levels of CCR4 ligands, regulatory T cells and CD8-positive effector T cells,” said Yung-jue Bang, a professor of medical oncology at Seoul National University Hospital. Bang will lead the further clinical development of FLX-475 with Hanmi.

Rapt is enrolling patients in a phase I/II study of FLX-475 as a monotherapy and in combination with Keytruda (pembrolizumab, Merck & Co.) in patients with charged tumors. Hanmi will conduct a phase II trial in Korea and China and expects part of those results to come out in the first half of 2020, the spokeswoman said. 

Founded in 2015, Rapt is focused on oral small-molecule therapies for patients with oncological and inflammatory diseases. The company uses its discovery and development engine to develop small molecules designed to modulate the critical immune responses underlying the diseases.   

In addition to FLX-475, it has three drug candidates under development. RPT-193, a lead candidate, is a small-molecule CCR4 antagonist that blocks the recruitment of inflammatory immune cells, known as T helper type 2 (Th2) cells, which are clinically implicated in allergic inflammatory disorders. RPT-193 is undergoing phase I development targeting atopic dermatitis and asthma and other allergic diseases. RPT-GCN2i and HPK1, both targeting solid tumors, are at the discovery stage.   

Hanmi is one of the leading pharmaceutical companies in Korea. Founded in 1973, it has been focused on the treatment of cancers, metabolic diseases, immune system diseases and other conditions, rare diseases and intractable diseases. The company has been active in collaborations with global pharmaceutical companies such as Sanofi SA, Genentech Inc., China’s Innovent Biologics Inc., and U.S. firms Athenex Inc., Allegro Ophthalmics LLC and Spectrum Pharmaceuticals Inc.

The Korean company has licensed out drug candidates to Sanofi (long-acting diabetes program Quantum Project), Genentech (Raf inhibitor HM-975573), and China’s Zai Lab Ltd. (EGFR-mutant selective inhibitor olmutinib). Hanmi also partnered in the development of a glucagon-like peptide (GLP)-1/glucagon dual receptor agonist HM-12525A with Johnson & Johnson in 2015; however, the American corporation returned the development and commercialization rights after phase II obesity trials in June, and Hanmi had to forego up to $810 million in potential milestone payments from J&J.

Hanmi’s (KRX:128940) stock price closed at ₩321,500 ($270) on Thursday.

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