VANCOUVER, B.C. – So far, monoclonal antibodies that specifically target IL-23p19 are showing promise for treating chronic plaque psoriasis and are usually well tolerated, Dr. Elisabeth Riedl said at the World Congress of Dermatology.
The agents target the interleukin (IL)-23 cytokine, which is important in the induction of T-helper-17 cells in psoriasis and several other inflammatory disorders, said Dr. Riedl of the department of dermatology at Mount Sinai Hospital in New York. IL-23 has two subunits – p40, which it shares with IL-12, and p19, which is specific for IL-23, she said. Based on earlier research, the effectiveness of psoriasis treatments that target the p40 subunit seems to depend mostly on their ability to neutralize IL-23, not IL-12, she noted.
That observation helped spur several psoriasis trials of monoclonal antibodies that target IL-23p19, according to Dr. Riedl. Among the most promising of the monoclonal antibodies is BI 655066, which significantly outperformed placebo in a randomized, double-blind phase I trial reported earlier in 2015. At week 12, 87% of patients who received intravenous or oral BI65506 achieved a PASI (Psoriasis Area and Severity Index) 75 score, while 58% achieved a PASI 90 score and 16% achieved PASI 100, compared with none of the placebo group.
Another IL-23p19 inhibitor, guselkumab (CNTO 1959), beat placebo in a small randomized, double-blind phase I trial, Dr. Riedl noted. All patients who received a single subcutaneous injection of 300 mg of guselkumab achieved a PASI 75 score, and about 80% achieved PASI 90, compared with none of the placebo group, she noted.
The third IL-23p19 inhibitor, tildrakizumab (MK-3222), also beat placebo at all doses tested in a three-part, randomized, placebo-controlled phase I trial, Dr. Riedl said. Furthermore, the histopathology of a subgroup of patients revealed significant decreases in lesions, compared with baseline, and a significant correlation between histopathologic and clinical scores, she noted. “In phase II, there was a significant response for all dosing cohorts, with a durable response to 52 weeks,” she added.
The primary safety concern for IL-23 inhibitors appears to be increased infection risk, although patients with genetic diseases connected to the IL-23/Th17 pathway already are at increased risk for infections such as candidiasis, mycobacteriosis, salmonellosis, and staphylococcal and Klebsiella infections, Dr. Riedl noted. “Ustekinumab targets IL-12/IL-23 and so far has shown a favorable safety profile,” she said, pointing to a 5-year follow-up study of the antibody that found no increase over time in adverse events and similar rates of adverse events among dosing groups.
Infections and headaches were the most commonly reported adverse events in phase I and II trials of targeted anti–IL-23p19 antibodies, Dr. Riedl said. In the phase I trial of BI 655066, rates of adverse events were similar for treatment and placebo except for nasopharyngitis, which affected 13% of the BI 655066 group and none of the placebo group, she noted. Guselkumab also was associated with similar rates of overall adverse events, compared with placebo, in its phase I trial, although 6 of 20 patients who received guselkumab developed infections, including two upper respiratory tract infections and one event each of bronchitis, folliculitis, viral gastroenteritis, herpes simplex infection, lower respiratory tract infection, vaginal infection, and nasopharyngitis, she said. Tildrakizumab was generally well tolerated in its phase IIb trial, she added. Serious adverse events that might have been related to treatment were rare but included bacterial arthritis, lymphedema, melanoma, stroke, epiglottitis, and knee infection.
Taken together, the data for IL-23p19 inhibitors are encouraging, according to Dr. Riedl. “The results suggest that selective inhibition of IL-23p19 is a promising target for novel therapies,” she said.
Dr. Riedl reported receiving grant support or serving as a consultant, advisory board member, or speakers bureau member for Abbvie, Celgen, Merck, Pfizer, and Janssen.