Alongside R1 Therapeutics, Mestag Therapeutics and iDEL Therapeutics also brought in money on Tuesday, helping to push their respective cancer portfolios forward.
Biopharma had a fruitful fundraising day on Tuesday, led by R1 Therapeutics’ oversubscribed series A haul to advance novel treatments for kidney diseases.
The California-based startup is coming onto the biopharma scene with $77.5 million in initial funds, according to a Tuesday news release, as well as a potentially first-in-class drug to help temper phosphate levels in patients with chronic kidney disease. Abingworth, F-Prime and DaVita Venture Group co-led the moneymaking push.
R1 will use its series A proceeds to advance the global development of AP306, a pan phosphate transporter inhibitor that the biotech claims is “the only agent that blocks the ‘active’ transport” of phosphate. Other phosphate-lowering agents only passively restrict its transport, R1 said.
AP306 was originally developed by Chugai and came to R1 via the China-based biotech Alebund Pharmaceuticals, which gave R1 an exclusive worldwide sublicense to the drug—though the specific financial terms of this agreement remain under wraps. Alebund will retain ownership over AP306 in the Greater China region.
AP306 has already completed Phase 2a testing in China, with results in February 2025 demonstrating a significant decrease from baseline in serum phosphate levels. Compared with Sanofi’s phosphate binder Renvela, approximately 20% more patients on AP306 achieved the range of phosphate levels recommended in the Kidney Disease: Improving Global Outcomes guidelines.
R1 plans to collaborate with Alebund on a global Phase 2b study for AP306, set to begin later this year, according to the press release.
The drug “represents a fundamentally new approach to treating hyperphosphatemia,” R1 CEO Krishna Polu said in a statement. “AP306 has the potential to deliver superior efficacy with substantially lower pill burden compared to current phosphate binder therapies.”
Also bringing in money on Tuesday was Mestag Therapeutics, which raised $40 million in a push backed by some of the industry’s biggest names, including Johnson & Johnson, Forbion and Google Ventures. The financing will help bankroll the Phase 1 STARLYS study of Mestag’s bispecific antibody for solid tumors. STARLYS is set to start mid-2026, according to the biotech’s press announcement.
iDEL Therapeutics also closed its seed round on Tuesday, raising €9 million (about $10.4 million). The company’s technology involves directly delivering cancer drugs into the cytosol of cancer cells, an approach that can be applied to both large and small molecules. Thursday’s proceeds will help push two proprietary lead programs toward the clinic.
IDEL is backed by BiomedVC with participation from NRW.Venture, KHAN Technology Transfer Fund II and Gründerfonds Ruhr.
