US-based biotech Allakos has announced that two Phase II clinical trials for atopic dermatitis and chronic spontaneous urticaria with its lead drug lirentelimab failed to meet their primary endpoints. 

In the Phase II ATLAS trial (NCT05155085) assessing lirentelimab for patients with atopic dermatitis, the primary endpoint – measuring the proportion of patients achieving a 75% reduction from baseline in Eczema Area and Severity Index (EASI-75) – did not achieve statistical significance, with 23% of patients treated with lirentelimab achieving EASI-75 compared to 18% of patients in the placebo group. 

The primary endpoint also fell short in the Phase IIb MAVERICK trial (NCT05528861) assessing patients with chronic spontaneous urticaria, with those in the lirentelimab group experiencing a change of -27% in urticaria activity score (UAS7), compared to a change of -26% in the placebo group. 

In response to these results, Allakos said it is initiating a workforce reduction of approximately 50% to reduce costs and ensure an extended cash runway. Additionally, the company will now also halt all lirentilimab-related activities. 

Allakos’ stock has plunged 59% after announcing the results on 16 January, compared to the price on the previous trading day of 12 January.  

Allakos will now concentrate its efforts on AK006, a humanised IgG1 monoclonal antibody candidate. An ongoing Phase I study for AK006 in healthy volunteers is set to progress, with the completion of its single and multiple ascending dose cohorts expected by Q1 2024.

While lirentelimab targeted Siglec-8, which is found on mast cells and eosinophils, AK002 is an agonist of Siglec-6, which is exclusively expressed on mature mast cells. Mast cells and eosinophils are types of immune cells, and are studied to understand a drug’s activity. In the ATLAS study, blood eosinophil counts of lirentelimab-treated patients decreased by 96% compared to 15% for those on placebo.  

The San Carlos, California-headquartered company plans to launch a Phase I trial for intravenous AK006 in chronic spontaneous urticaria in Q2 2024, anticipating topline data by the end of the year. 

In the announcement accompanying the results, chief medical officer of Allakos Craig Paterson said: “We are disappointed that these trials did not meet their primary endpoint, particularly given the need for new treatment options for patients with these severe diseases. Given that neither trial met its primary endpoint, we have decided to not pursue further clinical development of lirentelimab.”