Dianthus Therapeutics Inc (NASDAQ:DNTH) saw its shares rise 25.6% on Monday after the company disclosed an early go decision for the Phase 3 CAPTIVATE trial evaluating claseprubart in chronic inflammatory demyelinating polyneuropathy - CIDP.
The company arrived at the go decision after Part A of the study produced 20 confirmed responders while fewer than the originally planned 40 participants had completed the open-label portion. That outcome surpassed the pre-specified target response rate of 50 percent. The original trial criteria required 20 confirmed responders out of the first 40 participants.
An independent Data Safety Monitoring Board reviewed the data and endorsed the go decision. Dianthus reported no related serious infections, no clinical signs of autoimmune activation, and no related serious adverse events or discontinuations in the data disclosed with the update.
Following the interim readout, Dianthus said it will retain the 300 mg/2 mL subcutaneous dosing administered every two weeks in Part A and will engage with regulators to remove the 600 mg/4 mL dose arm from Part B. The company also adjusted its enrollment expectations for the CAPTIVATE program: it now expects to enroll up to 256 patients in Part A with the intent to randomize 128 patients into Part B. Those figures are reduced from the previously planned 480 enrollments in Part A and 192 randomized patients in Part B. Dianthus expects to deliver Part B top-line guidance by the end of 2026.
In addition to the CIDP program, the company provided near-term guidance for other clinical efforts. Dianthus indicated it plans to initiate a Phase 3 trial in myasthenia gravis in mid-2026, with Phase 3 top-line results anticipated in the second half of 2028. The company also said Phase 2 results for multifocal motor neuropathy are expected in the second half of 2026.
Market analysts updated their views following the announcement. Truist Securities analyst Danielle Brill increased her price target on Dianthus to $110.00 from $63.00 and maintained a Buy rating. Guggenheim analyst Yatin Suneja reiterated a Buy rating with a $200.00 price target. Stifel characterized the update as a best-case outcome for the stock, noting that the early go decision, which implies a response rate of at least 50 percent, supports the hypothesis that claseprubart's improved potency versus riliprubart may produce benefits beyond dose improvements: "For the stock, today’s update represents a best-case outcome, in our view. With the early go-decision implying ≥50% response rate, these data add support to the hypothesis that the improved potency of Claseprubart vs. Riliprubart may yield more than just improved dosing."
The company-provided timelines and reduced enrollment targets will shape the development path and reporting cadence for CAPTIVATE. Dianthus has indicated target milestones for related programs but did not change the dates provided in its update.
Summary of key developments:
- Early go decision for Phase 3 CAPTIVATE after 20 confirmed responders in fewer than 40 Part A completers.
- No related serious infections, autoimmune activation symptoms, or related serious adverse events or discontinuations reported.
- Company maintains 300 mg/2 mL biweekly dose in Part A, will seek to remove 600 mg/4 mL arm from Part B, and reduces planned enrollment for Parts A and B.