globenewswire news

• Samsara BioCapital, a leading biotech investor active across private and public markets, joins global investor syndicate 
• Funds will be used to advance AP306, a first-in-class pan phosphate transporter inhibitor in development as a monotherapy for hyperphosphatemia in patients on dialysis
• Investment comes ahead of Phase 2b topline data, expected in H1 2027

REDWOOD CITY, Calif., Sept. 30, 2026 (GLOBE NEWSWIRE) -- R1 Therapeutics, Inc (“R1”), a clinical-stage biopharmaceutical company developing first-in-class therapies for patients with kidney disease, today announced an expansion of its Series A financing to $80.5 million, with new investment from Samsara BioCapital.

Samsara BioCapital joins an investor syndicate that includes Abingworth, DaVita Venture Group, F-Prime, Curie.Bio, SNMA Capital (previously Symbiosis Capital Management) and U.S. Renal Care, following the oversubscribed $77.5 million round announced in March 2026. The proceeds will support the continued development of R1’s lead asset, AP306, a first-in-class pan phosphate transporter inhibitor, which is currently being evaluated as a monotherapy in a global Phase 2b trial for hyperphosphatemia in patients with chronic kidney disease (CKD) on dialysis. Topline data from the trial are expected in the first half of 2027.

Krishna Polu, M.D., Co-Founder, President and CEO of R1 Therapeutics, said: “Samsara brings a rare combination of scientific depth and a track record of investing in kidney companies across the private and public markets. Their decision to join ahead of the Phase 2b readout is a strong endorsement of our novel approach to addressing hyperphosphatemia. With our global trial underway, their support, alongside that of our existing syndicate, further strengthens our ability to generate the clinical data needed to bring AP306 to patients.”

Abe Bassan, Partner at Samsara BioCapital, added: "Managing phosphate levels remains one of the greatest challenges in dialysis care, with limited innovation for patients over the past several decades. With AP306, R1 is pursuing a novel mechanism of action that inhibits active phosphate transport, offering a differentiated alternative to traditional phosphate binders. We are pleased to join the investor syndicate and look forward to supporting the team as they advance AP306 through Phase 2b and beyond.”

Phosphate binders have been the standard of care for 60 years,¹ yet more than 70% of US dialysis patients fail to achieve normal phosphate levels,² and uncontrolled hyperphosphatemia contributes to cardiovascular disease, bone disease and mortality.³ AP306 is the only agent that blocks the "active" transport of phosphate, targeting three key transporters in the gut, with the potential for rapid, effective phosphate lowering at a substantially reduced treatment burden.

The multi-center, randomized, double-blind, placebo-controlled Phase 2b study (NCT06712654) is being conducted at clinical sites across the US and in China through R1's global partnership with Alebund Pharmaceuticals (Jiangsu) Limited (HKEX: 09637) ("Alebund").

For further information:

Optimum Strategic Communications
Mary Clark, Isabelle Abdou, Eleanor Cooper
Tel: +44 20 3922 0900
Email: r1therapeutics@optimumcomms.com

About R1 Therapeutics

R1 Therapeutics is a clinical-stage biopharmaceutical company focusing on the development of first-in-class therapies for patients with kidney disease. Its lead program, AP306, targets hyperphosphatemia in patients with chronic kidney disease on dialysis, a condition associated with serious bone and cardiovascular complications and poorer outcomes when phosphate remains uncontrolled. AP306 is a first-in-class pan phosphate active transport inhibitor designed to block three key phosphate transporters in the gut, with the potential to deliver rapid and effective phosphate lowering with a significantly reduced treatment burden. R1 has licensed exclusive global rights outside of Greater China to AP306 from Alebund Pharmaceuticals and is advancing a global Phase 2b development program. AP306 was originally discovered by Chugai Pharmaceutical Co., Ltd. and subsequently licensed to Alebund Pharmaceuticals in 2021. R1 launched in March 2026 with an oversubscribed $77.5 million Series A financing co-led by Abingworth, DaVita Venture Group, and F-Prime, with participation from Curie.Bio, SNMA Capital and U.S. Renal Care. The round was subsequently expanded to $80.5 million with the addition of Samsara BioCapital. For more information, visit www.r1therapeutics.com and follow R1 on LinkedIn.

About Samsara BioCapital

Founded in 2017, Samsara BioCapital is a leading biotech investment firm focused on identifying opportunities across public and private markets. Samsara invests across the full spectrum from early-stage start-up to late-stage clinical assets with a focus on companies that will have a significant impact on patients and address high unmet medical needs. Samsara works with entrepreneurs and top-tier management teams that they believe will have a meaningful impact on innovative therapeutics. The Samsara team has deep expertise in biotech with significant experience working together prior to founding the firm. The team is led by Srinivas Akkaraju, who has over twenty-two years of industry experience and has an MD and a PhD in Immunology from Stanford University.

References

1. Fissel R et al. 2016 Phosphate binder pill burden, patient-reported non-adherence, and mineral bone disorder markers: Findings from the DOPPS. Hemodial Int. 2016 January; 20(1): 38–49. doi:10.1111/hdi.12315
2. United States Renal Data System. 2024. USRDS 2024 Annual Data Report. National Institutes of Health, National Institute of Diabetes and Digestive and Kidney Diseases.
3. Ketteler M, Block GA, Evenepoel P, et al. 2017 Executive summary of the 2017 KDIGO Chronic Kidney Disease–Mineral and Bone Disorder (CKD-MBD) Guideline Update: what's changed and why it matters. Kidney Int. 2017;92:26–36