Background Tofacitinib is a novel, oral Janus kinase inhibitor for the treatment of rheumatoid arthritis (RA).
Objectives To evaluate the malignancies that occurred in Japanese patients in the tofacitinib RA programme from the Phase (P) 2, P3, and long-term extension (LTE) studies up to April 2013.
Methods Data were pooled from 2 randomised P2, 1 randomised P3 study and 1 ongoing open-label LTE study (database not locked). Patients (pts) in P3 and LTE studies were treated with tofacitinib 5 or 10 mg twice daily; P2 included additional dosages (LTE pts rolled over from the P2 and P3 studies).
Results A total of 556 patients (1479 pt-yr) received tofacitinib in the P2, P3 and LTE studies. Nineteen pts receiving tofacitinib (all doses) reported malignancies; the most common were gastric (5 cases) and breast cancer (3 cases). There were 2 cases of lymphoma. No cases of non-melanoma skin cancer (NMSC) were reported. The overall incidence rate (IR, events per 100 pt-yr) for all malignancies was 1.29 (95% confidence interval [CI]: 0.82, 2.01). The IRs (95% CI) of all malignancies broken down into 0-6, 6-12, 12-18, 18-24, 24-30, 30-36, 36-42 and >42 months based on exposure to tofacitinib were 0.39 (0.06, 2.79), 2.13 (0.89, 5.11), 1.82 (0.68, 4.84), 1.45 (0.47, 4.49), 1.55 (0.50, 4.80), 0.60 (0.08, 4.24), 0.98 (0.14, 6.98) and 1.01 (0.14, 7.20), respectively. The cumulative IRs (95% CI) of all malignancies from 0-6, 0-12, 0-18, 0-24, 0-30, 0-36 and 0-42 months were 0.39 (0.06, 2.79), 1.23 (0.55, 2.73), 1.41 (0.76, 2.62), 1.42 (0.82, 2.44), 1.44 (0.88, 2.35), 1.33 (0.83, 2.14) and 1.30 (0.82, 2.07), respectively. The number of cases in each time interval was small, with resultant wide and overlapping 95% CIs.
Conclusions Among Japanese patients in the tofacitinib RA clinical development programme the most common malignancies were gastric (5 cases) followed by breast (3 cases) cancer; both malignancies were also common in the general Japanese population . The rate of malignancies was stable over time, but numerically higher in both 6-12 and 12-18 month periods compared with other time intervals. Overall rates appear similar to the global RA tofacitinib programme population , published rates for biologic DMARDs, and rates from the tocilizumab Japanese RA clinical trial population [3,4]. Further monitoring within the clinical practice setting is warranted to evaluate the risk of malignancy over time.
Center for Cancer Control and Information Services, National Cancer Center, Japan (http://ganjoho.jp/pro/statistics/en/table_download.html).
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Disclosure of Interest : Y. Tanaka Grant/research support: Pfizer Japan Inc, Consultant for: Pfizer Japan Inc, T. Takeuchi Grant/research support: Pfizer Japan Inc, Consultant for: Pfizer Japan Inc, H. Yamanaka Grant/research support: Pfizer Japan Inc, Consultant for: Pfizer Japan Inc, T. Hirose Shareholder of: Pfizer Inc, Employee of: Pfizer Japan Inc, S. Toyoizumi Employee of: Pfizer Japan Inc, S. Zwillich Shareholder of: Pfizer Inc, Employee of: Pfizer Inc, J. Geier Shareholder of: Pfizer Inc, Employee of: Pfizer Inc, R. Riese Shareholder of: Pfizer Inc, Employee of: Pfizer Inc