Pfizer, Inc. recently announced top-line results from two Phase III clinical trials of tofacitinib, a novel, oral Janus kinase (JAK) inhibitor that is being investigated for the treatment of adults with moderate-to-severe chronic plaque psoriasis: OPT Compare (A3921080) and OPT Retreatment (A3921111). These are the first two of five studies in the Phase III Oral Psoriasis Treatment (OPT) Program, one of the largest global clinical trial programs in moderate-to-severe chronic plaque psoriasis to date, according to Pfizer. Top-line results for the OPT Pivotal 1 and OPT Pivotal 2 trials (A3921078 and A3921079) 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.

OPT Compare, a 12-week, non-inferiority study, compared the efficacy and safety of tofacitinib 5mg and 10mg twice-daily (BID) to high-dose etanercept 50mg (Enbrel) twice-weekly (BIW), the approved starting dose for Enbrel for the first 12 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 10mg BID dose. Tofacitinib did not meet the non-inferiority criteria to high-dose Enbrel at the 5mg BID 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 5mg and 10mg BID 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 5mg and 10mg BID 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.  The results of OPT Retreatment will provide relevant information to physicians in clinical practice, as it is common for patients with psoriasis to stop and restart therapy.

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.