Dianthus Therapeutics (DNTH) investor relations material

Interim Analysis and Study Design Update

• Early GO decision made for the CAPTIVATE phase 3 trial in CIDP after achieving 20 confirmed responders with fewer than 40 participants in Part A, surpassing the original target.

• Responder definition required a confirmed NCAT improvement at two consecutive visits, starting at week 5, with a high efficacy bar.

• No concerning safety events observed, including no autoimmune activation or serious infections, supporting a favorable safety profile.

• Study design updated: 600 mg arm dropped, Part B now a two-arm RCT (300 mg vs placebo), and responder target for Part A raised from 40% to 50%; patient enrollment requirements reduced, expediting trial completion.

• Planned changes to the CAPTIVATE study design are pending regulatory approval.

Efficacy and Patient Population Insights

• Response rates in CAPTIVATE exceeded those seen in prior riliprubart studies, with higher efficacy observed across all patient subgroups.

• The NCAT endpoint is considered the most rigorous efficacy metric in CIDP trials, and confirmation at two consecutive visits was required.

• Study included refractory, stable, and naive patients, with consistent results across geographies and no subgroup driving outcomes; CAPTIVATE includes a broader patient population than comparator studies.

• No clustering of response times; responses were distributed across the 13-week evaluation period, reflecting CIDP heterogeneity.

• The trial design, including open-label Part A and rapid switch from standard of care, contributed to strong enrollment and patient-friendly participation.

Comparative Context and Market Opportunity

• Claseprubart aims to address significant unmet needs in CIDP, offering efficacy, safety, and convenience advantages over IVIG, and targeting a potential blockbuster profile.

• CAPTIVATE's accelerated progress has narrowed the timeline gap with competitors, potentially reducing riliprubart's first-to-market advantage.

• US CIDP market is large and underserved, with current SoC presenting significant unmet needs and a high treatment burden; surveyed neurologists report high demand for safer, more effective, and convenient alternatives.

• Active C1s inhibition (riliprubart) has shown ~50% improvement in SoC-treated and SoC-refractory patients in prior studies.

• Claseprubart is positioned to compete as a first-line biologic in multiple neuromuscular markets, with ongoing and upcoming studies in gMG and MMN.