Jasper Therapeutics (NASDAQ:JSPR) presented updated clinical data from its BEACON study in chronic spontaneous urticaria (CSU) and from an open-label extension (OLE) that enrolled participants from BEACON and the company’s SPOTLIGHT study in chronic inducible urticaria (CIndU). Management highlighted what it described as rapid onset of symptom control, durable efficacy with repeat dosing, and a safety profile that it believes supports chronic administration of briquilimab, its anti-KIT monoclonal antibody.
Program overview and mechanism
CEO Jeet Mahal said briquilimab’s profile is driven by its high-affinity binding to the KIT receptor, which “directly block[s] receptor signaling and trigger[s] apoptosis of mast cells.” Management emphasized that subcutaneous dosing achieves a rapid and high peak concentration (Cmax), which the company associates with mast cell depletion and significant reductions in disease activity within the first two to four weeks.
BEACON update: Cohort 9.1 efficacy and safety
The webinar focused on new data from eight additional patients enrolled in BEACON Cohort 9.1, which uses a 240 mg loading dose followed by 180 mg every eight weeks. Of the eight additional patients, six received briquilimab and two received placebo. Two additional patients have been enrolled in a separate cohort evaluating 240 mg every eight weeks, but they have not yet reached the 12-week endpoint and were not included in the update.
Edelman reported pharmacodynamic effects consistent with earlier cohorts, including “rapid and deep” reductions in tryptase. Clinically, the company presented mean UAS7 improvements through week 12, stating that UAS7 declined by an average of 31 points at week 12 in Cohort 9.1.
Response metrics highlighted by the company included:
- Five of six briquilimab-treated patients achieved a complete response (CR; UAS7 = 0) by week three.
- Four of six had a CR at week 12 while on the 180 mg maintenance dose.
- Management said complete responses were reported in the majority of patients by week two.
On safety in Cohort 9.1, Edelman said briquilimab was well tolerated, with no dose-limiting toxicities and no discontinuations due to treatment-related adverse events. Potentially KIT-related observations in the cohort included a taste change in one patient and a decrease in neutrophil count in another, which he said was transient and resolved during the study. The company added that KIT-related events were generally low-grade, often resolved with repeat dosing, and did not lead to discontinuations or dose delays.
Open-label extension: repeat-dose results in CIndU and CSU
Jasper also provided an update from its OLE using briquilimab 180 mg every eight weeks. Edelman said 63 patients were included in the safety dataset and 53 patients had completed at least 12 weeks on study for the efficacy analyses presented. Median follow-up was reported as over 200 days.
In the CIndU portion of the OLE (17 patients), the company described rapid and durable symptom control across challenge assessments conducted at weeks 2, 8, 16, and 24, with most evaluations occurring eight weeks after the prior dose. Edelman reported:
- 69% of CIndU patients achieved a complete or partial response at week two.
- 65% maintained a complete or partial response at week 16 (eight weeks after the last dose).
In the CSU portion of the OLE (36 patients), Jasper presented UAS7 trends through week 20 and response rates over time. Edelman said responses could be seen as early as week one and appeared to increase with additional dosing. He reported that 62% of CSU patients achieved a complete response at week 20, described as four weeks after the third dose.
Across the OLE, Edelman said safety observations potentially related to KIT inhibition remained infrequent and generally low grade, with most resolving during repeat dosing.
Phase 2b plans, leadership transition, and funding considerations
Management said the BEACON and OLE datasets support initiating a phase 2b study as part of a CSU registrational program targeted to start in the second half of 2026. Mahal said Jasper expects the phase 2b to enroll approximately 75 to 100 adult CSU patients and to evaluate two dose regimens versus placebo.
In Q&A, Mahal said the company’s board initiated the recent CEO change based on Jasper’s development stage and the leadership needed to advance into phase 2b and pivotal studies, noting his experience taking therapeutics from early development through BLA or NDA submission.
On phase 2b design, Mahal said the current plan is an “operationally adaptive phase 2b/3” under a single protocol, with an emphasis on maintaining adequate time between the 2b and 3 portions to make the right dose selection. He added that a separate phase 3 study would still be required for registration to provide two adequately controlled studies.
The company declined to specify the exact dose regimens it will take forward, saying the analysis is ongoing. Edelman said one regimen is likely to include a loading dose followed by maintenance dosing, while another may use a fixed dose every eight weeks, but he stressed nothing has been finalized. He also noted that weight may be an important factor in optimizing dosing.
Regarding trial execution, Edelman said site selection will focus on experienced allergists and dermatologists, ideally those with prior CSU trial experience. He also acknowledged that even expert clinicians can misdiagnose CSU “up to 20%-30% of the time,” and Mahal said power calculations will account for that risk. Jasper said it has sufficient drug supply and operational capability to support a second-half 2026 start, with timing dependent on dose selection analysis and regulatory discussions.
On financing, CFO Herb Cross said Jasper’s current guidance is that existing capital extends through the middle of 2026 and into the third quarter, and that the company will need to raise additional capital. Management also discussed the potential strategic value of a partnership to support broader development across multiple indications, though no specific partnership plans or timing were provided.
About Jasper Therapeutics (NASDAQ:JSPR)
Jasper Therapeutics, Inc (NASDAQ: JSPR) is a clinical-stage biopharmaceutical company focused on translating advances in immunobiology into therapies for serious and rare diseases with unmet medical needs. The company’s research and development efforts center on engineered biologics and cell-based approaches designed to address complications in hematologic conditions and improve outcomes in transplant medicine.
Central to Jasper’s pipeline is JSP191, a monoclonal antibody targeting the CD117 receptor, which is being evaluated to enhance donor hematopoietic stem cell engraftment in patients undergoing stem cell transplantation.
