Concizumab haemophilia trials paused over safety concerns

The occurrence of non-fatal thrombotic events in Phase III study participants has called into question the safety of concizumab.

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The developers of concizumab (anti-TFPI mAB) have announced they are pausing the three clinical trials testing its safety and efficacy as a once-daily prophylactic to prevent bleeding in haemophilia patients. The decision was taken because non-fatal thrombotic events occurred in patients enrolled on the Phase III programmes.

Novo Nordisk, who created concizumab, is working with an independent Data Monitoring Committee to assess whether these events mean the trials cannot be continued, no conclusions have been made as of yet.

The company is pausing the Phase III explorer7 trial, testing the drug in haemophilia A or B patients taking inhibitors towards FVIII or FIX and the Phase III explorer8 trial, studying the drug in haemophilia A or B patients without inhibitors, both started in 2019. The company is also pausing the Phase II explorer5 trial which began in October 2017. This study was set up to evaluate the efficacy and safety of once-daily prophylactic subcutaneous concizumab delivered in a pen device to reduce the number of bleeds of haemophilia A patients.

The explorer5 study has 15 patients and an estimated total of around 109 patients are currently being treated with concizumab. All recruitment for trials has ceased and patients being treated with concizumab will be taken off the drug.

“While it is disappointing to pause the trials, patient safety is of utmost importance to Novo Nordisk – both for those taking part in our clinical trials and those who use our products on a daily basis” said Mads Krogsgaard Thomsen, Executive Vice President and Chief Science Officer of Novo Nordisk. “Together with relevant authorities, we will now carefully evaluate all available data and decide how to best move forward.”