Dianthus shares surge on positive CIDP trial data despite earnings miss
Early GO decision in CAPTIVATE study achieved ahead of schedule, cash runway extends into 2028
Dianthus Therapeutics shares surged Monday morning after the biotechnology company announced an early 'go' decision in its pivotal Phase 3 CAPTIVATE trial for chronic inflammatory demyelinating polyneuropathy (CIDP), reaching its responder target ahead of schedule despite reporting a wider-than-expected fourth-quarter loss.
The New York-based clinical-stage biotech said its independent Data Safety Monitoring Board confirmed that 20 confirmed responders were achieved with fewer than 40 planned participants, triggering the go/no-go decision earlier than the second quarter of 2026 guidance. The company's target was a 50% or greater response rate—defined as at least 20 confirmed responders out of the first 40 participants.
Shares of Dianthus, which trade on Nasdaq under the ticker DNTH, jumped more than 6% to $65.20, trading near their 52-week high of $64.67. The stock has gained more than 40% since February, fueled by clinical momentum around its lead asset claseprubart, a novel monoclonal antibody targeting autoimmune and inflammatory diseases.
The positive interim analysis comes as Dianthus reported a fourth-quarter net loss of $64.4 million, or $1.43 per share, wider than the $0.90 per share loss anticipated by analysts. Research and development expenses totaled $59.9 million for the quarter, while general and administrative costs reached $9.9 million. Revenue of $284,000 was minimal, consistent with the company's pre-commercial stage.
Despite the earnings miss, investors focused on the clinical success and strong financial position. As of December 31, 2025, Dianthus reported cash, cash equivalents, and investments of $514.4 million, which the company projects will fund operations into 2028. The substantial runway provides multiple catalysts ahead, including top-line data from the gMG trial in the second half of 2028.
The CAPTIVATE trial is a two-part Phase 3 study evaluating claseprubart in CIDP, a rare autoimmune disorder affecting the peripheral nerves. Part A consists of an open-label phase where participants receive 300mg of claseprubart administered subcutaneously every two weeks for up to 13 weeks, with response defined as a one-point improvement in the adjusted INCAT score from baseline. Part B is a double-blind, placebo-controlled period of up to 52 weeks where responders are randomized to assess relapse prevention.
The safety profile demonstrated in the interim analysis appears favorable, with the DSMB noting no related serious infections, no clinical symptoms of autoimmune activation, and no related serious adverse events or discontinuations. Dianthus plans to continue Part A with the 300mg subcutaneous dose every two weeks and engage regulators to remove the higher-dose arm from Part B, adjusting enrollment to up to 256 patients in Part A to randomize 128 in Part B.
The company expects to provide top-line guidance for CAPTIVATE Part B by the end of 2026. Analysts at major firms have issued price targets averaging $83.55, representing significant upside from current levels, with 14 analysts rating the stock a buy or strong buy and none recommending hold or sell.
Beyond CIDP, Dianthus is advancing its pipeline in other autoimmune indications. The company anticipates initiating a Phase 3 registrational trial of claseprubart for generalized Myasthenia Gravis (gMG) in mid-2026, with top-line results expected in the second half of 2028. The gMG trial will evaluate two dosing regimens: 300mg administered every two weeks and every four weeks.
The CIDP market represents a significant commercial opportunity, valued between $2.27 billion and $8.43 billion in 2025, with projections estimating growth to $3.32 billion by 2030. The increasing prevalence of rare autoimmune neuropathies, wider availability of immunoglobulin therapies, and advancements in electrodiagnostic testing are driving market expansion, with North America identified as the largest regional market.
Dianthus, which went public in 2024, is developing claseprubart as a potential best-in-class treatment for multiple autoimmune conditions. The antibody targets FcRn, a receptor involved in recycling immunoglobulin G antibodies, with the potential to reduce pathogenic IgG levels while maintaining normal immune function—a mechanism that could offer advantages over existing therapies.