Roivant's TYK2 Drug Achieves Phase II Success, Advances to Key Eye Disease Trial

Roivant has reported promising results in a mid-stage study of its Pfizer-partnered dual TYK2/JAK1 inhibitor, brepocitinib, which is paving the way for a Phase III trial in non-anterior non-infectious uveitis (NIU) later this year.

Brepocitinib, originally transferred to Roivant’s Priovant Therapeutics from Pfizer in 2022, targets both TYK2 and JAK1 receptors. This positions it as a potential competitor to Bristol Myers Squibb’s Sotyktu (deucravacitinib). Roivant has already initiated a Phase III study and performed a separate study on NIU to determine whether a second pivotal program would be justified.

In the study, 26 patients with active NIU were randomized to receive either 45mg or 15mg of brepocitinib daily. Approximately 67% of participants were administered the higher dose. Additionally, all patients were given a 60mg daily dose of prednisone for the first two weeks, which was gradually tapered off by week eight.

The primary endpoint of the study evaluated the rate of treatment failure. This composite measure included ocular inflammation, visual acuity, and discontinuation due to adverse events or the need for rescue therapy. By week 24, treatment failure rates were 29% for the higher dose group and 44% for the lower dose group.

These results compare favorably with AbbVie's Phase III trials supporting Humira's (adalimumab) approval for similar indications in 2016. AbbVie’s larger studies showed Humira treatment failure rates of 54.5% and 39.1%, while placebo groups had failure rates of 78.5% and 55%. Differences in study design, such as the duration of prednisone tapering, make direct comparisons challenging, but the oral administration of brepocitinib could present a more convenient alternative to injectable treatments like Humira.

Secondary efficacy endpoints were also met at week 24, including improvements in haze grades, visual acuity, and macular thickness. Notably, macular edema resolved in 43% of participants in the 45mg cohort who had the condition at the beginning of the study.

Regarding safety and tolerability, Roivant noted that the findings were consistent with previous brepocitinib trials. No new safety or tolerability issues were reported, and the drug's safety profile is in line with other JAK inhibitors, which are widely used despite their black box warnings.

Encouraged by these results, Roivant plans to proceed with a Phase III trial in NIU in the latter half of 2024. Additionally, pivotal data for brepocitinib in dermatomyositis is anticipated next year.

The data disclosure coincides with news of a $1.5 billion share buyback, through which Roivant will acquire the entire stake held by Sumitomo Pharma for $648 million. Sumitomo initially invested in Roivant in 2019.