LMWH Equals Warfarin for Active Cancer Patient Recurrent VTE Prevention

Tinzaparin does not significantly reduce the rate of recurrent venous thromboembolism in active cancer patients compared with warfarin

  • Date: 19 Aug 2015
  • Author: Lynda Williams, Senior medwireNews Reporter
  • Topic: Supportive Care

medwireNews: The low molecular weight heparin (LWMH) tinzaparin has comparable efficacy to warfarin for the prevention of recurrent venous thromboembolism (VTE) in patients with active cancer, suggest CATCH trial findings.

Over 6 months of follow-up, the primary composite endpoint of recurrent deep vein thrombosis (DVT), fatal or nonfatal pulmonary embolism (PE) and incidental VTE occurred in 31 of the 449 patients treated with tinzaparin 175 IU/kg once daily for 6 months, giving a 6-month incidence of 7.2%.

Similarly, recurrent VTE was reported in 45 of the 451 patients who were randomly assigned to receive tinzaparin once daily for 5 to 10 days followed by 6 months of warfarin with a target international normalised ratio of 2.0 to 3.0, giving a 6-month incidence of 10.5%.

The tinzaparin and warfarin treatment groups also had comparable rates of major bleeding (12 vs 11 affected patients) and overall mortality (150 vs 138 patients).

Indeed, the only significant difference between the two treatments was a significantly lower rate of clinically relevant but nonmajor bleeding episodes with tinzaparin, with a hazard ratio (HR) of 0.58, the investigators report in JAMA.

Lead author Agnes Lee, from the University of British Columbia in Vancouver, Canada, and team compare their findings with those of the CLOT trial, which found the LMWH dalteparin to be more effective at preventing recurrent VTE than a vitamin K antagonist.

Both studies recruited patients with active cancer – defined as a confirmed diagnosis, disease progression or treatment in the past 6 months – and acute symptomatic proximal DVT and/or PE, but the actual rate of thromboembolism with warfarin was lower in the CATCH trial than had been anticipated, at 10.5% versus the expected 12.6%.

“This potentially affected the power of the trial to detect a benefit associated with tinzaparin”, the researchers explain.

They hypothesise that this lower than expected rate of VTE may “reflect critical differences” in the CATCH and CLOT populations, noting the current study’s patients had lower rates of current cancer treatment, metastases, prior history of VTE and mortality than those in CLOT.

“Consequently, the CATCH population had fewer risk factors for thrombosis and recurrent thrombosis than the CLOT population”, Agnes Lee et al summarise.

“It is possible that a significant reduction in recurrent VTE might be observed with tinzaparin in a higher-risk population.”

Reference

Lee AYY, Kamphisen PW, Meyer G, et al. Tinzaparin vs warfarin for treatment of acute venous thromboembolism in patients with active cancer. A randomized clinical trial. JAMA 2015; 314: 677–686. doi:10.1001/jama.2015.9243

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