Allakos (ALLK) Study Result summary

Study design and patient population

• Phase I, multi-center, randomized, double-blind, placebo-controlled study in chronic spontaneous urticaria (CSU) refractory to antihistamines, enrolling 34 adults randomized 2:1 to AK006 (720 mg IV every 4 weeks) or placebo over 14 weeks.

• Baseline disease activity was high (UAS7 ≥16, HSS7 ≥8), with 68% having UAS7 scores of 28–42; mean age was 44, 79% female, 76% white.

• 24% had prior omalizumab use; median CSU duration was 5.2 years; prior biologic treatment was allowed.

• Baseline demographics were well-balanced between arms.

Efficacy and safety results

• AK006 did not demonstrate clinical efficacy versus placebo at week 14; mean UAS7 change was -8.2 for AK006 and -12.4 for placebo, with 8.7–9.1% achieving UAS7=0.

• Placebo response was consistent with other CSU trials.

• AK006 was well-tolerated with no serious adverse events; most adverse events were mild to moderate and did not lead to discontinuation.

• Common adverse events included headache, infusion reactions, and COVID-19, each in 8.7% of AK006-treated subjects.

Interpretation and next steps

• Full target saturation was achieved at the selected dose, but preclinical efficacy did not translate to humans.

• Biopsy data showed target engagement but assay limitations prevented robust communication of results.

• No evidence to support AK006 activity in CSU; potential in other indications remains speculative.

• All AK006-related activities will be discontinued, with a 75% workforce reduction and focus on winding down operations; about 15 employees will be retained to explore strategic alternatives and maintain compliance.