Jasper Therapeutics to stop ETESIAN study due to drug product lot issue

Jasper Therapeutics (JSPR) is reporting updated data from Company’s BEACON Phase 1b/2a study of subcutaneous briquilimab in adult participants with CSU and providing an update on the program. Briquilimab administration resulted in deep and rapid disease control in the 240mg and 360mg single-dose cohorts, with 8 of 9 of participants enrolled across both cohorts achieving a complete response, and with 7 of 9 achieving a clinical response by week 2. In addition, BEACON participants who rolled over into the open-label extension study dosing at 180mg Q8W demonstrated robust clinical efficacy with 8 of 11 participants achieving a complete response at 12 weeks. Results from the 240mg Q8W and the 240mg followed by 180mg Q8W dose cohorts appear to be confounded by an issue with one drug product lot used in those cohorts, with 10 of the 13 patients dosed with drug from the lot in question. The Company is investigating the drug product lot in question and expects to have the results of that investigation in the coming weeks. Key observations noted in those 10 patients were lower than expected drops in mean tryptase levels and no discernable impact on UAS7 scores. The 2 participants enrolled in the cohorts that have been confirmed as being dosed with drug product from a different lot both achieved complete response. New drug product is being provided to clinical sites to transition the 10 patients who were initially dosed with drug from the lot in question to drug product for their next administration that has demonstrated efficacy in earlier and ongoing cohorts. The Company also plans to enroll an additional 10-12 patients in total across the 240mg Q8W and the 240mg followed by 180mg Q8W cohorts to ensure a robust data set to inform the Phase 2b CSU study. Data from the additional BEACON patients is expected in 4Q 2025 and commencement of the Phase 2b study is now expected in mid-2026. The Company has also determined that the drug product lot in question was used to treat participants enrolled in the ETESIAN trial evaluating briquilimab in asthma. As a result, and in order to focus resources on advancing briquilimab in CSU, the Company is halting the study and pausing development in asthma. In addition, the Company is halting development in SCID and will be implementing a number of other cost cutting measures, including a potential restructuring, to extend runway and reduce expenses.