Assessing AEs
As with response levels, serum dupilumab levels at week 16 did not predict AEs including dupilumab-associated ocular surface disease (DAOSD), which impacted 46.4% of 216 patients who reported AEs. These findings also contradict what happens with biologics in other diseases such as psoriasis and inflammatory bowel disease, said Dr. Sidbury, wherein serum drug levels may predict both clinical response and side-effect risks.
A previous study showed that lowering dupilumab levels led to improvement in DAOSD. Authors of the current study therefore surmised that DAOSD development might be more associated with interpatient variability in IL-4R-alpha expression than with serum drug levels. “More research is necessary to confirm the hypothesis of interpatient variability of the IL-4Ra and the pharmacokinetics of dupilumab,” they concluded.
For now, said Dr. Sidbury, the study helps clinicians look beyond serum drug levels when patients respond inadequately to dupilumab. Moreover, added Dr. Silverberg, study results mean that physicians must find other ways to predict dupilumab response levels. “We need better predictors of clinical response – theranostic markers that we could test the patient to and understand how well they’re going to do,” he said.
Be it dupilumab or any other medication, he said, physicians lack even confirmatory biomarkers to reflect when a drug is working well. “Right now, we go with clinical assessments. But if it’s not drug levels, we have to figure out why some patients do markedly better than others.”
It was not unreasonable, Dr. Silverberg said, for the investigators to seek a biomarker in blood rather than tissue. “But in this disease, we believe that the more important place to look for biomarkers and drug levels would be in the skin itself. So we are still left with the issue” that drug levels in tissue might reflect response when serum levels do not.
The study was supported by grants from AbbVie, Eli Lilly, Leo Pharma, Pfizer, and Sanofi. Study patients participated in the BioDay Registry, which is sponsored by Sanofi, Regeneron, AbbVie, Eli Lilly, LEO Pharma, and Pfizer; the sponsors had no role in the study design and conduct. Dr. Spekhorst discloses receiving speaking fees from Abbvie outside the work; disclosures of other authors included receiving advisory, speaking consulting, and/or investigator fees from Sanofi Genzyme during the study. Several authors had no disclosures.
Dr. Simpson has been an investigator and consultant for Regeneron and Sanofi, makers of dupilumab. Dr. Silverberg has been an investigator, consultant, and speaker for Regeneron and Sanofi. Dr. Sidbury has been a clinical investigator for all dupilumab pediatric trials. (His institution has a contract with Regeneron and Sanofi, but he receives no money from the arrangement.)