HUTCHMED sovleplenib hits Phase III primary endpoint in wAIHA
HUTCHMED has presented Phase III results from its ESLIM-02 study of sovleplenib in warm antibody autoimmune haemolytic anaemia, reporting that the oral Syk inhibitor met its primary endpoint with a durable response rate of 66% versus 15% for placebo over weeks five to twenty-four (p<0.0001). The data were presented at the European Hematology Association Congress in Stockholm on 11 June 2026 and were selected for the EHA Press Programme.
The randomised, double-blind, placebo-controlled study enrolled 90 adult patients in China who had relapsed or were refractory to at least one prior line of standard treatment. Patients received sovleplenib 300 mg once daily or placebo for twenty-four weeks. Beyond the primary endpoint, the overall response rate, defined as haemoglobin of at least 100 g/L with an increase of at least 20 g/L from baseline without rescue therapy, reached 70% in the sovleplenib arm versus 22% in the placebo arm (p<0.0001). Median time to response was 3.1 weeks versus 6.3 weeks for placebo, and the median cumulative duration of response among responders was 16.1 versus 6.1 weeks. The proportion of patients requiring protocol-defined rescue therapy fell to 16% with sovleplenib compared with 54% on placebo, and fewer patients needed red blood cell transfusions (11% versus 43%).
Safety and regulatory milestones
Sovleplenib's safety profile compared favourably with placebo in the study. Grade three or higher treatment-emergent adverse events were reported in 43% of the sovleplenib group versus 59% of the placebo group, and no TEAE-related deaths or treatment discontinuations were recorded in the active arm. The most common severe adverse event in the placebo group was the underlying condition itself, reflecting the inadequacy of existing therapies.
China's National Medical Products Administration accepted a New Drug Application for sovleplenib in wAIHA for priority review in April 2026, following the NMPA's award of Breakthrough Therapy Designation for the same indication in March 2026. Phase II data from ESLIM-02 were published in The Lancet Haematology in January 2025, and Phase III results from a separate HUTCHMED study of sovleplenib in immune thrombocytopenia have also appeared in that journal. A resubmitted NDA for the ITP indication received priority review from the NMPA in February 2026.
Market context
Professor Bing Han of Peking Union Medical College Hospital, co-leading principal investigator on ESLIM-02, noted that "the wAIHA treatment paradigm has remained stagnant for decades, with patients often trapped in a cycle of high-dose steroids and frequent relapses," adding that the data demonstrate targeting the Syk pathway can achieve both rapid and durable control of haemolysis.
The wAIHA space is notable for the absence of approved targeted therapies, making it an attractive regulatory opportunity for companies that can demonstrate durable haemoglobin control. Several Syk and BTK inhibitors are in clinical development for autoimmune blood disorders more broadly, and the positive ESLIM-02 dataset will increase scrutiny of the class as a whole. HUTCHMED retains global rights to sovleplenib, which gives the company flexibility over eventual licensing or out-partnering strategy outside China. Analysts will focus on whether HUTCHMED seeks regulatory filings in Western markets, where wAIHA patient populations are smaller but where the lack of approved targeted options could support an accelerated regulatory pathway under FDA or EMA rare-disease provisions.