FOSUN PHARMA has initiated a Phase 3 clinical trial for its novel drug candidate, FXS6837, targeting patients with paroxysmal nocturnal hemoglobinuria (PNH) who have not received prior complement inhibitor therapy, as per a recent update on the Clinicaltrials registry.

This marks the first Phase 3 study for FXS6837, according to publicly available information. The trial is designed as a randomized, open-label, active-controlled study to evaluate the efficacy and safety of FXS6837 capsules compared to eculizumab in approximately 90 PNH patients who are complement inhibitor-naive. Participants will receive either FXS6837 capsules or eculizumab for 24 weeks. The primary endpoint is the proportion of participants achieving a hemoglobin (Hb) level ≥ 120 g/L in at least three of four measurements between weeks 18 and 24, without receiving red blood cell transfusions (defined as no transfusions from week 2 to week 24).

FXS6837 (XH-S003) is a small-molecule complement factor B (CFB) modulator that works by regulating the immune system, targeting diseases associated with abnormal complement activation, such as primary IgA nephropathy and PNH. In August 2025, FOSUN PHARMA granted global rights (excluding China) for FXS6837 to UK-based biotechnology firm Sitala Bio in a deal valued at over $600 million.

According to the Insight database, only three drugs in the CFB inhibitor pipeline have been approved for market globally: Novartis's iptacopan, Lannet's lanocopam, and Haisco's sipocopam. Hengrui Pharma's licanocopam was submitted for market approval in China in January 2026 and is currently under review. Additionally, three other candidates have entered Phase 3 clinical trials, including those from FOSUN PHARMA, Nanjing Chia Tai Tianqing, and Ionis Pharmaceuticals/Roche. The Ionis Pharmaceuticals/Roche candidate is an antisense oligonucleotide (ASO) drug targeting CFB.