Safety assessment of new antithrombotic agents: lessons from the EXTEND study on ximelagatran

BACKGROUND: Ximelagatran, the first oral direct thrombin inhibitor, was shown to be an effective antithrombotic agent but was associated with potential liver toxicity after prolonged administration. OBJECTIVES AND METHODS: The aim of the EXTEND study was to assess safety and efficacy of extended administration (35 days) of ximelagatran or enoxaparin for the prevention of venous thromboembolism after elective hip replacement and hip fracture surgery. A follow-up period, including assessment of liver enzymes (in particular alanine aminotransferase; ALAT), until post-operative day 180 was planned, with visits at days 56 and 180. RESULTS: Randomization and administration of study drugs were stopped following a report of serious liver injury occurring 3 weeks after completion of ximelagatran treatment. At the time of study termination, 1158 patients had been randomized and 641 had completed the 35-day treatment; with 303 ximelagatran and 265 enoxaparin patients remaining in the study through to the day 56 follow-up visit. Overall, 58 patients showed an ALAT increase to >2x upper limit of normal: 31 treated with enoxaparin, 27 with ximelagatran. Three ximelagatran patients also showed symptoms potentially related to liver toxicity. Eleven ximelagatran patients showed an ALAT increase after study treatment ended. The clinical development of ximelagatran was terminated and the drug withdrawn from the market. Evaluation of the relative efficacy of the two treatments as specified in the protocol was impossible due to the premature termination of the study. CONCLUSIONS: Prolonged administration of ximelagatran was associated with an increased risk of liver toxicity. In a substantial proportion of patients, ALAT increase occurred after treatment withdrawal. The findings seen with ximelagatran should be considered when designing studies with new antithrombotic agent

Oral, direct Factor Xa inhibition with BAY 59-7939 for the prevention of venous thromboembolism after total hip replacement

Background: Joint replacement surgery is an appropriate model for dose-ranging studies investigating new anticoagulants. Objectives: To assess the efficacy and safety of a novel, oral, direct factor Xa (FXa) inhibitor - BAY 59-7939 - relative to enoxaparin in patients undergoing elective total hip replacement. Methods: In this double-blind, double-dummy, doseranging study, patients were randomized to oral BAY 59-7939 (2.5, 5, 10, 20, or 30 mg b.i.d.), starting 6-8 h after surgery, or s.c. enoxaparin 40 mg once daily, starting on the evening before surgery. Treatment was continued until mandatory bilateral venography was performed 5-9 days after surgery. Results: Of 706 patients treated, 548 were eligible for the primary efficacy analysis. The primary efficacy endpoint was the incidence of any deep vein thrombosis, non-fatal pulmonary embolism, and all cause mortality; rates were 15%, 14%, 12%, 18%, and 7%for BAY 59-7939 2.5, 5, 10, 20, and 30 mg b.i.d., respectively, compared with 17% for enoxaparin. The primary efficacy analysis did not demonstrate any signi.cant trend in dose-response relationship for BAY 59-7939. The primary safety endpoint was major, postoperative bleeding; there was a significant increase in the frequency of events with increasing doses of BAY 59-7939 (P = 0.045), but no signi.cant di.erences between individual BAY 59-7939 doses and enoxaparin. Conclusions: When eficacy and safety were considered together, compared favorably with enoxaparin for the prevention of venous thromboembolism in patients undergoing elective total hip replacement. \ua9 2006 International Society on Thrombosis and Haemostasis