Acelyrin’s lead drug flops in phase 3 trial, wiping out half of its market value

Acelyrin, clinical trial data, inflammatory diseases, failed trials, ulcerative colitis, phase 3 trial, IPO, stock price

Acelyrin, a biotech company based in Los Angeles, has delivered a shocking blow to its investors. Despite successfully raising an impressive $540 million in a rare biotech IPO a few months ago, the company now finds itself grappling with the failure of its leading candidate in a phase 2b/3 clinical trial for an inflammatory disease. This setback has caused Acelyrin’s share price to plummet by a staggering 58% during premarket trading.

The company had initially garnered significant attention and investment for its development of an IL-17A inhibitor, differentiating itself by using a small protein instead of a monoclonal antibody, promising higher potency. The pivotal phase 3 trial focused on moderate to severe hidradenitis suppurativa, a crucial test for this unique approach. Unfortunately, Acelyrin’s candidate, izokibep, failed to outperform the placebo on the primary endpoint, leading to a substantial drop in the stock price to $11.60 before the market opened on Tuesday. It’s worth noting that the share price had soared to around $28 in anticipation of the trial results.

During the trial, 175 patients were either administered a placebo or one of two izokibep regimens. After 16 weeks of treatment, the izokibep arms showed no statistically significant improvement over the placebo group when it came to a 75% or greater reduction in total abscess and inflammatory nodule count. The izokibep arms reported response rates of 39% and 34%, while the placebo group had a response rate of 29%.

Despite this disappointing outcome, Acelyrin remains confident in the future of izokibep. The company has initiated a second late-phase clinical trial for hidradenitis suppurativa and is actively exploring strategies to address the issues of patient discontinuations and increased placebo responses, which were observed but not fully explained during the initial trial.

“First, I would like to thank the patients and clinicians in this study, without whom we would not be able to continue to learn about how best to treat this debilitating disease. Although the overall study did not meet statistical significance, izokibep appears to be demonstrating consistent early and high orders of response for patients suffering from hidradenitis suppurativa without safety or tolerability limitation. The consistent and early achievement of HiSCR100, along with our prior izokibep experience in Psoriatic Arthritis, continues to demonstrate the potential of izokibep for resolution of disease, especially in difficult to treat tissues. These results further support our ongoing evaluations of 160 mg QW dosing in HS, as well as for additional indications, including uveitis and PsA, the largest potential indication for izokibep.”

– Shao-Lee Lin, MD, PhD, founder and CEO of ACELYRIN

Financially, Acelyrin is well-equipped to navigate this setback, with a substantial cash reserve of $823 million as of June. Additionally, the company has upcoming data releases, including top-line data from a phase 2b/3 clinical trial in psoriatic arthritis, expected in the first quarter of the next year.

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