, results from a phase 2a study showed.
Dr. Lawrence F. Eichenfield
PDE4 inhibitors are a promising therapeutic target for inflammatory diseases because “they can increase cyclic adenosine monophosphate levels and subsequently reduce the production of proinflammatory cytokines,” lead study author Lawrence F. Eichenfield, MD, of the dermatology department at the University of California, San Diego, and colleagues wrote. The paper was published online in JAMA Dermatology.
Currently Available Treatments
For plaque psoriasis, the FDA approved the topical PDE4 inhibitor roflumilast in 2022. The oral PDE4 inhibitor apremilast has shown to be effective for plaque psoriasis and is well tolerated, and “it has been associated with gastrointestinal adverse events (AEs) such as nausea and diarrhea,” the researchers wrote.
For AD, crisaborole is the only approved topical PDE4 treatment, and it is associated with application site burning and stinging, they wrote.
An Experimental Alternative
The new study tested a topical PDE4 inhibitor known as PF-07038124, which is being developed by Pfizer. It is designed to be “a potent, oxaborole-based PDE4 inhibitor [that shows] immunomodulatory activity in T-cell–based assays, contributing to inhibition of [interleukin]-4 and IL-13; thus, it could provide therapeutic benefit in the treatment of AD and plaque psoriasis,” the authors wrote.
The phase 2a study was conducted from December 21, 2020, to August 18, 2021. Researchers at 34 sites in four countries randomized 104 patients with mild to moderate AD (70) or plaque psoriasis (34) to receive PF-07038124 as a 0.001% topical ointment or a vehicle only once daily for 6 weeks.
The primary end point was the percent change from baseline in the Eczema Area and Severity Index (EASI) total score among patients with AD and in the Psoriasis Area and Severity Index (PASI) score among patients with plaque psoriasis at week 6. Safety measures of interest included treatment-emergent adverse events.
Overall, the mean age of the 104 patients was 43 years, 52.9%, were women, 3.8% were Asian, 12.5% were Black, and 83.7% were White. Most had moderate disease.
At week 6 in patients with AD, the PF-07038124 group showed statistically significantly greater improvement in the EASI total score, compared with vehicle group (−74.9% vs −35.5% respectively; least squares mean [LSM] difference, −39.4%; 90% CI, −58.8% to−20.1%]; P < .001).
Similarly, at week 6 in patients with plaque psoriasis, the PF-07038124 group demonstrated a significantly greater improvement in the PASI total score, compared with the vehicle group (LSM, −4.8; 90% CI, −6.2 to −3.4] vs 0.1; 90% CI, −1.5 to 1.7), for a difference of −4.9; 90% CI, −7.0 to −2.8; P < .001.
In safety outcomes, treatment-emergent adverse events were reported in 16 people receiving PF-07038124 and 26 people receiving a vehicle. The treatment-related adverse events were reported only in the vehicle groups across all indications, while no patients in the PF-07038124 groups experienced pain or skin reactions at the application sites.
The researchers acknowledged certain limitations of the trial, including its small size and the 6-week treatment period. “Unlike crisaborole, topical PF-07038124 was not associated with application site burning and stinging,” they noted. “To confirm persistence of efficacy and the safety profile of PF-07038124, long-term data should be collected in larger studies.”
Pfizer supported the study. Dr. Eichenfield reported receiving personal fees from Pfizer during the conduct of the study. He also has received grant support from, is consultant to, and/or is a member of the advisory board for many other pharmaceutical companies. Several other study authors reported similar disclosures.