Pfizer's new rheumatoid arthritis (RA) drug tofacitinib outperformed methotrexate in a phase III trial, while another study showed that its beneficial effects extend for up to four years.
The new data, which is scheduled for presentation at the American College of Rheumatology (ACR) meeting in Washington DC in November, 2012, adds to a growing body of evidence which suggests tofacitinib could be a major new treatment for moderate-to-severe RA.
The oral Janus kinase (JAK) inhibitor is the lead in its class and has already been filed for approval in Europe, Japan and the US, with the FDA due to deliver a verdict on the marketing application by November 21, 2012.
The new efficacy data come from the ongoing ORAL Start study, which is comparing tofacitinib to standard therapy with the disease-modifying anti-rheumatic drug (DMARD) methotrexate over two years in methotrexate-naïve patients.
Tofacitinib given as a single-agent oral therapy twice-daily was significantly superior to methotrexate in reducing the signs and symptoms of RA, and also in preventing the progression of joint damage characteristic of the disease, after a year's treatment.
Tofacitinib was recommended for approval by an FDA advisory committee in May, 2012, based on the results of earlier phase III trials, but the agency has asked for additional analyses of data from the drug's clinical trials programme. In particular, it is understood that it was looking for additional information on tofacitinib's effects on structural damage.
The FDA had been due to deliver a verdict on the application on August 23, 2012, but extended the review time by three months.
Meanwhile, follow-up data from a placebo-controlled study called ORAL Scan shows that the efficacy of tofacitinib was maintained over two years, without any major safety concerns, while Pfizer has also pooled data from phase II and III trials ready for presentation at ACR indicating the drug "showed a consistent safety profile and sustained efficacy over 48 months".
Analysts have predicted that it could become a major earner for Pfizer, with sales upwards of $2bn a year at peak in RA, and even further upside possible if trials in other indications such as psoriasis, inflammatory bowel disease and renal transplant are positive.