After issues with a batch of Jasper Therapeutics’ investigational antibody led to “lower” therapeutic effects in several patients, analysts at BMO Capital Markets said they “believe investors won’t feel comfortable coming back to the story.”
Issues with a batch of the investigational antibody briquilimab “confounded” the readout of Jasper Therapeutics’ Phase Ib/IIa BEACON study in chronic spontaneous urticaria, leading to “lower” therapeutic effects in patients treated with the compromised drugs, the company reported Monday.
Jasper’s shares plunged Monday, with the California biotech down 55% at market close. In the aftermath of the drug lot issues, Jasper will implement cost-cutting measures, including a potential strategic restructuring. The biotech had $48.8 million in cash and cash equivalents as of March 31.
Results from BEACON “were impacted by an inactive drug product lot,” analysts at William Blair said in a note to investors on Monday, adding that the two affected dose arms—240 mg and 240 mg loading dose followed by 180 mg every eight weeks—“were of high interest as potential doses” for the pivotal development of briquilimab.
For BMO Capital Markets, the lot issue could make Jasper stock a harder sell for investors. “Given the market environment,” the analysts wrote, “we believe investors won’t feel comfortable coming back to the story following today’s update.”
Jasper is developing briquilimab for chronic spontaneous urticaria (CSU), for which it is running BEACON, a randomized, double-blinded and placebo-controlled study with around 40 participating patients. The trial administered briquilimab in six ascending doses and Jasper on Monday reported data from 13 patients who were treated with the single 240 mg dose, or 240 mg loading dose followed by 180 mg injections every eight weeks.
Ten of those 13 patients received briquilimab from the compromised lots. Results showed that these patients had “lower than expected” improvements in mean tryptase levels, a key pharmacodynamic outcome of BEACON and a biomarker of CSU. Briquilimab treatment in these 10 patients also showed “no discernable impact” on scores in the Urticaria Activity Score, the study’s primary efficacy outcome.
Meanwhile, two patients treated with briquilimab from a different drug lot achieved a complete response.
The exact issue with the drug lot remains unknown and Jasper is currently looking into the matter. The company is also providing new drug product to transition these 10 patients into a new drug lot that has demonstrated efficacy in earlier cohorts. Jasper will also add 10 to 12 new patients across both the affected dose arms “to ensure a robust data set.”
Jasper expects to report data from these additional BEACON participants in the fourth quarter. Because of Monday’s lot issue, the company has also pushed back the start of a Phase IIb CSU study to mid-2026.
The lot issues also affected an asthma trial of briquilimab. Jasper will no longer pursue this indication for the antibody.
