Izokibep Reaches Key Efficacy Endpoints in Phase 3 HS Trial

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In a recent press release, Affibody, a partner of Acelyrin Inc.,announced positive results from its global phase 3 clinical trial of izokibep for hidradenitis suppurativa (HS) (NCT05905783).The trial, involving 258 participants, met primary endpoints of HiSCR75 at week 12, as well as the key secondary endpoints of HiSCR90 and HiSCR100.¹ 

“We are pleased that the phase 3 HS trial of izokibep met its primary endpoint and provided clinically meaningful responses as early as week 12 in this devastating disease. Importantly, we are further encouraged by the deepening responses seen at week 16, with a quarter of the patients achieving HiSCR100. Past experience tells us these responses will deepen even further with continued treatment,” wrote Nikolai Brun, chief medical officer of Affibody. “These results demonstrate that targeting IL-17A alone with greater potency can achieve the same or greater clinical responses than agents targeting IL-17 subunits more broadly, without their associated safety liabilities.”

Izokibep, a small protein therapeutic inhibiting IL-17A, has potential for robust tissue penetration due to its small size. Researchers hypothesized that these unique characteristics of izokibep may provide “clinically meaningful and differentiated benefits for patients,” which has been supported by clinical data. Izokibep has been administered to over 1000 patients, some of whom have been dosed for over 3 years.

The trial reported that 33% of patients receiving izokibep achieved HiSCR75 compared to only 21% of patients receiving placebo (p = 0.0294). In higher order endpoints, the efficacy of izokibep was even more pronounced. Specifically, 25% of patients on izokibep achieved HiSCR90, versus 9% on placebo (p = 0.0009), and 22% achieved HiSCR100 compared to 8% on placebo (p = 0.001).

The release stated that preliminary data from patients who continued to receive treatment through week 16 reveal even greater responses. At this later timepoint, 40% of patients on izokibep achieved HiSCR75, compared to 20% on placebo (p<0.05). Additionally, 27% of patients achieved HiSCR90 and 25% achieved HiSCR100, marking significant improvements from the earlier data.

“We are delighted that the phase 3 HS trial of izokibep was successful, again confirming the strength of the Affibody platform in immunology and inflammation. Today’s positive HS data and previously announced psoriatic arthritis (PsA) data support a path to approval for izokibep,” wrote David Bejker, chief executive officer of Affibody.² “Our partner Acelyrin has determined that a program of this breadth and size is best brought to market by a larger organization with the resources and existing footprint in these indications. Given our continuing confidence in izokibep’s best-in-class potential, underpinned by the breadth of efficacy and safety data generated across multiple indications, we will work with Acelyrin to bring izokibep to patients in need of novel treatments.”

The release stated that izokibep’s safety profile was consistent with prior studies and the IL-17A class, with no new safety signals identified. Notably, the study reported no cases of candida infection, liver toxicity, or suicidal ideation/behavior in the izokibep treatment group.

The positive results from this trial add to the growing body of late-stage trials supporting izokibep's efficacy across multiple indications. In addition to the positive phase 3 HS results, Acelyrin also announced that they will complete the ongoing HS and PsA trials but will not initiate the planned additional phase 3 studies in these indications. The company stated top-line data from the ongoing phase 2b/3 trial of izokibep in uveitis are expected in the fourth quarter of 2024.

References

1. Positive phase 3 results in hidradenitis suppurativa further strengthen competitive profile of izokibep. Affibody Medical AB. August 13, 2024. Accessed August 14, 2024. https://www.affibody.se/press/positive-phase-3-results-in-hidradenitis-suppurativa-further-strengthen-competitive-profile-of-izokibep/
2. Acelyrin, Inc. announces positive top-line results from its global phase 2b/3 clinical trial of izokibep in psoriatic arthritis. News release. BioSpace. March 11, 2024. Accessed August 14, 2024. https://www.biospace.com/article/releases/acelyrin-inc-announces-positive-top-line-results-from-its-global-phase-2b-3-clinical-trial-of-izokibep-in-psoriatic-arthritis/