Correction: This article has been updated to state the correct implication of the trial error on the izokibep program. A previous version incorrectly stated the trial in which the error was noted and its result. The headline and all paragraphs have been updated on 29 November to reflect this.

Immunology biotech Acelyrin has determined that its CRO partner Fortrea and a contracted vendor are responsible for a programming error in an ongoing study with its immunotherapeutic drug candidate izokibep in psoriatic arthritis.

This mistake has prompted the company to implement an audit for the izokibep program, including a trial for moderate to severe hidradenitis suppurativa (HS). In September, when Phase IIb/III HS study (NCT05355805) failed to meet its endpoint of achieving a 75% reduction in total abscesses and inflammatory nodules, the company’s stock more than halved overnight and has not yet recovered to the levels seen before 11 September.

While a press release issued by Acelyrin outlining the error did not identify Fortrea as the CRO in question, a 26 November SEC filing stated that both Acelyrin and Fortrea notified EU regulators about the errors in the trial.

The errors were noted in an ongoing Phase IIb/III psoriatic arthritis study (NCT05623345), a double-blind, placebo-controlled, multi-centre study evaluating the safety and efficacy of izokibep.

The study has four treatment arms with izokibep or placebo ; 160mgdosed every week (QW), 160mg dosed every other week (Q2W), 80mg dosed every four weeks (Q4W) and placebo.

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By GlobalData

Acelyrin states that this protocol was incorrectly used by the vendor engaged by the CRO, which resulted in some patients in two of the arms—160mg Q2W and 80 mg Q4W— receiving the investigational drug and placebo in a “random order”.  The company estimates that the other two trials arms are unlikely to be impacted by this error.

Since being made aware of the error, the company says it has corrected the programming and dosing sequence for the ongoing PsA trial and is also actively working to “determine the implications” of the errors.

Acelyrin also stated that the “confounding factors,”—namely discontinuation without adverse events and notable increases in placebo rates at the tail-end of the study—observed in the HS trial led to the company fortifying quality control measures for both the HS and psoriatic arthritis (PsA) studies.