AstraZeneca details why its bone-drug Phase 3 trial failed

AstraZeneca shared new details on its failed HICKORY Phase 3 trial of efzimfotase alfa, an enzyme replacement therapy for the rare bone disease hypophosphatasia, saying the study missed its primary endpoint largely because the placebo group with adult-onset disease performed better than expected. The drug achieved a least-squares mean difference of 17.05 metres on the six-minute walk test at week 25 versus placebo, falling short of statistical significance (p=0.1675). In a post hoc analysis, 45.2 percent of treated patients reached a clinically meaningful improvement compared with 30.0 percent on placebo, and secondary measures of physical function, pain and fatigue favored the drug, the company said.

The data arrive as the FDA reviews efzimfotase alfa under priority review, with a decision expected in the first half of 2027. The therapy is AstraZeneca’s next-generation successor to Strensiq, which sold $1.7 billion last year but is approved only for infantile- and juvenile-onset disease, and the company has cited peak-sales potential of $3 billion to $5 billion for the new drug.