Business Description

Overview We are a clinical-stage biotechnology company focused on developing therapeutics targeting mast cell driven diseases such as Chronic Spontaneous Urticaria (“CSU”), Chronic Inducible Urticaria (“CIndU”) and asthma and we continue to consider additional indications in mast cell driven diseases for potential future development. We have also historically explored development programs in diseases where targeting diseased hemopoietic stem cells can provide benefits, such as stem cell transplant conditioning regimens, but those programs have been discontinued and we are exclusively focused on mast cell driven diseases. Our lead product candidate, briquilimab, is a monoclonal antibody designed to block stem cell factor (“SCF”) from binding to and signaling through the CD117 (“KIT”) receptor on mast and stem cells. The SCF/KIT pathway is a survival signal for mast cells and we believe that blocking this pathway may lead to depletion of these cells throughout the body, including in the lungs and in the skin, which could lead to significant clinical benefit for patients with mast-cell driven diseases such as asthma and chronic urticarias. To that end, we are focusing on advancing a portfolio of clinical programs in mast cell driven diseases. Development highlights include: CSU - BEACON Study We commenced the Phase 1b/2a BEACON study in CSU in late 2023. The BEACON study is a randomized, double-blind, and placebo-controlled Phase 1b/2a trial evaluating multiple ascending doses of briquilimab both as a single dose (“SD”) (240mg & 360mg) as well as with repeat dosing (multiple dose levels from 10mg Q8W up to 240mg Q8W) as a therapy for adult patients with moderate to severe CSU. We reported positive preliminary data from the first 8 dosing cohorts (10mg, 40mg, 80mg Q8W, 120mg Q8W & Q12W, 180mg Q8W & Q12W and 240mg SD), in January 2025. We also reported preliminary data from 3 additional cohorts (360mg SD, 240mg Q8W and 240mg/180mg Q8W) in July 2025, and reported additional positive preliminary data from new patients enrolled in the 240mg/180mg Q8W cohort in January 2026. In general, data generated in the BEACON study has been positive with strong efficacy and a favorable safety profile observed in CSU patients. Highlights of the BEACON study data presented in those updates were as follows: ● Briquilimab demonstrated a rapid onset of clinical efficacy with clinical responses seen as early as 1 week post-dose and complete responses observed as early as week 2 post-dose. ● Briquilimab drove deep and meaningful clinical responses at dose levels of 180mg or higher, most notably with 100% of patients in the 240mg single dose cohorts achieving complete responses in the first 8 weeks. ● Briquilimab was well-tolerated and demonstrated a favorable safety profile: o KIT-related adverse events (“AEs”) were generally transient, low-grade events; o The majority of AEs observed were resolved while on study prior to subsequent doses; and o No dose delays, missed doses or discontinuations were reported due to AEs possibly related to KIT blockade. 1 While the data generated to date in the BEACON study has generally been positive, in the July 2025 data update, results from the 240mg Q8W and the 240mg/180mg Q8W dose cohorts demonstrated an atypical absence of UAS7 reduction in 11 of the 13 patients enrolled, and as a result, we launched an investigation into those two cohorts. Factors examined included clinical site conduct, site dosing procedures, patient selection criteria, as well as potential product lot variability in one lot of drug product first introduced into the BEACON study in those two cohorts. We also provided new clinical drug supply from a different lot for ongoing dosing of existing patients and subsequently enrolled an additional 10 patients in aggregate across those two cohorts. Based on the work conducted during the investigation, we concluded the anomalous efficacy results in these two cohorts was not the result of any issues with the investigational product used, or from drug substance (“DS”) or drug product (“DP”) manufacturing or distribution processes, but rather appeared to be an issue resulting from patient selection process/criteria at certain clinical sites participating in the study.…