Pfizer Releases Topline Data for JAK Inhibitor

Pfizer has released top-line results from two Phase III trials of tofacitinib, an oral Janus kinase (JAK) inhibitor that is being investigated for the treatment of adults with moderate-to-severe chronic plaque psoriasis. The company is currently running five Phase III trials in this area, under the Oral Psoriasis Treatment (OPT) program. The reported trials were OPT Compare and OPT Retreatment.

OPT Compare is a 12-week, non-inferiority study comparing the efficacy and safety of tofacitinib 5 and 10 mg twice-daily to high-dose Enbrel 50 mg twice-weekly, the approved starting dose for ENBREL for the first twelve weeks, and placebo for the treatment of adult patients with moderate-to-severe chronic plaque psoriasis. Top-line results from the OPT Compare study showed that tofacitinib met the primary endpoint of non-inferiority to high-dose Enbrel at the 10 mg dose, but did not meet the non-inferiority criteria to high-dose Enbrel at the 5 mg dose. The dose-response relationship observed for tofacitinib in this trial is consistent with the findings from the Phase II trial. Additionally, rates of important safety events were similar across the active treatment arms.

OPT Retreatment is a 56-week study comparing the efficacy and safety of withdrawal and retreatment with tofacitinib 5 and 10 mg to placebo for the treatment of adult patients with moderate-to-severe chronic plaque psoriasis. The OPT Retreatment study met its primary efficacy endpoints at the 5 and 10 mg doses by demonstrating that a greater proportion of patients continuing tofacitinib treatment maintained their response during the treatment withdrawal phase compared to patients who switched to placebo. Additionally, among patients who lost an adequate response, many were able to recapture their response upon retreatment with tofacitinib.

No new safety signals for tofacitinib were observed in these studies, and the efficacy and safety profile of tofacitinib in psoriasis remains consistent with that seen in the Phase II clinical trial. Full analyses of the OPT Compare and OPT Retreatment data, including additional efficacy and safety data, will be submitted for presentation at a future scientific meeting.

Top-line results for the OPT Pivotal 1 and OPT Pivotal 2 trials are anticipated in the second quarter of 2014, and these four studies, in addition to a long-term extension study, will form the potential psoriasis submission package to regulatory authorities.