Background  CHAMPION was a phase III trial that compared adalimumab with methotrexate and placebo for chronic plaque psoriasis.

Objectives  To determine the relationship between methotrexate dosing and improvement in psoriasis for patients in CHAMPION.

Methods  Methotrexate-treated patients in CHAMPION received step-up dosing to 15 mg per week during the first 8 weeks. At week 8, PASI 50 responders (early responders, ER) were to continue with 15 mg weekly for the next 8 weeks; PASI 50 nonresponders were to receive 20 mg weekly for the next 4 weeks, followed by 20 mg weekly if they achieved ≥ PASI 50 at week 12 (late responders, LR), or 25 mg weekly if not (late nonresponders, LN). Outcomes were assessed post hoc for patients in these groups who completed CHAMPION.

Results  One hundred and three methotrexate-treated patients were analysed: 40 ER, 22 LR and 41 LN. Week 16 mean percentage improvement from baseline in Psoriasis Area and Severity Index was greatest in the ER group, nearly as good in LR, and poor in LN; PASI 75/90/100 response rates were 70%/32%/18%, 41%/9%/5% and 5%/0%/0%, respectively. Among patients with a PASI 75 response at week 16, 72% were in the ER group (comprising 27% of patients overall) and 23% were in the LR group.

Conclusions  Nearly all week 16 PASI 75 responders in CHAMPION achieved a PASI 50 response at week 8 or 12, with maximum methotrexate dosages of 15 or 20 mg per week, respectively. Week 12 may be an appropriate time to discontinue methotrexate treatment in patients who are not achieving good responses.