Chinese PDE4B Inhibitor Prifemilast Defeats Amgen's Otezla in Phase 3 Head-to-Head Psoriasis Trial

Chinese drugmaker Newsoara Biopharma and its partner cAMPfield Therapeutics have delivered a striking blow in the competitive psoriasis market, demonstrating that their experimental oral treatment outperformed Amgen's established therapy in a head-to-head clinical trial.

The results, presented Wednesday at the Fall Clinical Dermatology Conference in Las Vegas, position prifemilast—a selective PDE4B inhibitor—as a potential best-in-class therapy for moderate-to-severe plaque psoriasis, a chronic inflammatory skin condition affecting millions worldwide.

In the Phase 3 trial involving 607 adult patients, prifemilast administered at 20 milligrams once daily achieved a 64.6% PASI 75 response rate at Week 16, compared with 35.3% for apremilast, Amgen's twice-daily oral therapy sold as Otezla. The 29.3 percentage-point difference represents nearly double the efficacy of the competitor drug and met statistical significance with a P-value below 0.0001.

The results also showed that 55.6% of patients on prifemilast achieved skin clearance or near-clearance, measured by the sPGA 0/1 endpoint, versus 31.3% on apremilast—a 24.3 percentage-point advantage that likewise reached statistical significance.

"In a head-to-head clinical study, demonstrating superiority over apremilast is a challenging goal," said Bill Gerhart, chief executive of cAMPfield Therapeutics. "Prifemilast achieved clear advantages on both co-primary endpoints, fully demonstrating its potential to become a best-in-class PDE4 inhibitor."

The trial design pitted prifemilast, given as a single 20 mg daily dose without titration, against apremilast administered at 30 mg twice daily with dose escalation per U.S. prescribing guidelines. The apremilast performance in this trial aligned with historical data from the ESTEEM-1 and ESTEEM-2 pivotal studies, which reported PASI 75 rates of 33.1% and 28.8%, respectively, at Week 16.

Safety profiles were broadly comparable between the two treatment arms. Serious adverse events occurred in 4.0% of patients receiving prifemilast versus 2.5% on apremilast, while discontinuation rates due to adverse events were 2.0% and 1.5%, respectively. In a separate placebo-controlled Phase 3 study, discontinuation rates during the 16-week treatment period ranged from 1.7% to 1.8% for prifemilast, similar to the 1.8% observed with placebo.

Prifemilast's mechanism of action targets PDE4B, the subtype most closely associated with anti-inflammatory activity, while minimizing inhibition of PDE4D, which is linked to dose-limiting side effects. The molecule was designed to limit central nervous system penetration and features slow absorption with a long half-life, supporting once-daily dosing.

The drug's development history spans multiple companies and continents. Originally discovered by vTv Therapeutics, the molecule was licensed to Newsoara in 2018 for development and commercialization in China and select Asia-Pacific markets. In February 2026, Newsoara secured global exclusive rights, and that June, cAMPfield Therapeutics was formed following a $180 million Series A financing round, acquiring global development and commercialization rights for all indications outside Greater China.

Beyond psoriasis, cAMPfield is advancing prifemilast into Phase 2 clinical trials for inflammatory bowel diseases, including ulcerative colitis and Crohn's disease. The compound has been administered to more than 1,000 subjects across clinical studies, with over 250 patients exposed to the drug for 52 weeks.

Newsoara plans to file a New Drug Application with Chinese regulators by year-end 2026 for plaque psoriasis. The drug remains investigational and has not received approval in any country or region.

The clinical data were presented as two posters at the conference, with abstracts and full posters expected to be published in the Dermatology Online Journal. The findings have not yet undergone peer review.