Pfizer's abrocitinib beats blockbuster Dupixent in phase 3 eczema trial, but key questions remain

Rivals are closing in on Sanofi and Regeneron’s Dupixent. With AbbVie’s Rinvoq having already bested Dupixent in atopic dermatitis, Pfizer has now chalked up its own efficacy win over the blockbuster incumbent without sharing key details of safety data that could shape the category.

Earlier work has already pointed to the potential for Pfizer’s JAK1 inhibitor abrocitinib to outperform Dupixent. The latest phase 3b data confirm the advantages of abrocitinib while leaving unanswered questions about whether Pfizer has the complete package of attributes needed to make a big dent in sales of Dupixent. 

Investigators randomized 728 patients with moderate to severe atopic dermatitis to receive 200 mg of abrocitinib orally once a day or 300 mg of Dupixent via subcutaneous injection every other week for 26 weeks. The groups received placebo tablets or injections to blind them to which therapy they were receiving. 

Abrocitinib outperformed Dupixent against co-primary endpoints that looked at changes on itch and eczema scales at weeks 2 and 4. Pfizer is yet to share numbers, stating only that the trial met its co-primary endpoint.

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As with all JAK inhibitors, the safety of abrocitinib will receive close scrutiny. Pfizer said more people who received abrocitinib experienced adverse events, although the proportion of patients who had serious and severe adverse events or dropped out because of side effects were similar. Two people in the abrocitinib arm died, but neither death was found to be related to the study drug.

Further details of the safety and tolerability of abrocitinib, which Pfizer plans to share at a scientific meeting, will determine whether patients and physicians see the oral drug as a better option than the well-established Dupixent. Small numbers of patients experienced low blood platelet counts in an earlier trial. Existing JAK inhibitors, including Rinvoq, carry black box warnings. 

Pfizer had expected to add abrocitinib to the list of approved JAK inhibitors by now, but its plans have been held up by a delay at the FDA. Having initially targeted an April decision, the FDA delayed the PDUFA date earlier this year.