J&J and Protagonist Announce Two Phase 3 Wins for Potential Blockbuster IL-23 Drug

Johnson & Johnson and Protagonist Therapeutics have announced promising Phase 3 trial results for their oral IL-23 drug, icotrokinra, in treating plaque psoriasis. The drug, previously known as JNJ-2113, met its co-primary endpoints in a study involving 600 patients and also achieved the primary endpoint in a smaller trial of 300 patients, both comparing icotrokinra to a placebo.

In the larger study, 64.7% of patients taking 200 mg of icotrokinra daily experienced significant skin clearance, either fully or almost entirely, according to investigator assessments of IGA scores after 16 weeks. This is in stark contrast to only 8.3% of patients in the placebo group. Additionally, 49.6% of the icotrokinra group achieved at least 90% skin clearance based on PASI scores at 16 weeks, compared to just 4.4% in the placebo group.

Although J&J did not provide full data for the smaller study, it confirmed that the primary endpoint, IGA scores, was met when comparing icotrokinra to the placebo. The drug is also undergoing two additional plaque psoriasis studies directly comparing it to Bristol Myers Squibb’s Sotyktu, with results expected in the first half of 2025.

Over the past year, J&J has been building anticipation for icotrokinra. At a December 2023 investor event, the company highlighted the drug's potential to bolster its immunology portfolio, forecasting peak sales exceeding $5 billion across all indications. CEO Joaquin Duato emphasized icotrokinra's potential approval as a significant market event at a September investor conference.

TD Cowen analyst Tara Bancroft informed investors that icotrokinra is expected to lead the oral IL-23 market and may even rival injectable treatments. Despite icotrokinra’s PASI 90 results being slightly lower than in some Phase 2 trials, it still outperformed competitors like Sotyktu and Amgen’s Otezla in their respective pivotal trials. Both Sotyktu and Otezla are oral medications approved for psoriasis treatment.

Bancroft also pointed out the drug's substantial potential in other indications, with an ulcerative colitis readout anticipated in the first quarter of next year. J&J plans to initiate trials in psoriatic arthritis before April and eventually in Crohn’s disease, although specific timelines have yet to be disclosed.

The collaboration has been beneficial for Protagonist Therapeutics, which received over $170 million in milestones prior to Monday's readout. The recent Phase 3 successes secured another $165 million, as the companies revised their milestone framework last week to include an additional $50 million for the Phase 3 victories.

In return, Protagonist will forgo a $35 million milestone for an NDA filing and a $15 million milestone for dosing the third patient in a Phase 3 trial for an indication beyond plaque psoriasis. Both milestones are expected to be met in the near future.

Despite the positive news, Protagonist’s stock price, under the ticker $PGTX, saw a slight decline of approximately 3% on Tuesday morning.