Patients should also be informed about the risk of TE/TMA and the signs and symptoms of TE/TMA. “If repeated dosing of bypass agents is needed, particularly aPCC, patients should contact their hemophilia treatment center,” the researchers wrote. “If TE/TMA is suspected, platelet count, creatinine, d-dimer, and fibrinogen should be monitored. If TE/TMA occur, emicizumab should be held and aPCC discontinued until resolution. Upon resolution of TE/TMA, consideration should be given to restarting emicizumab on a case-by-case basis.”
As for laboratory considerations, the researchers noted that results of activated partial prothrombin time (aPTT) will be shortened in patients on emicizumab, often into the normal range even at low concentrations. In addition, one-stage aPTT based factor VIII activity assays will yield high factor VIII activities, even at low concentrations of the drug. “Health care providers including dentists, surgeons, and emergency room staff need to be informed of the effects of emicizumab on laboratory tests,” they wrote in a poster at THSNA 2018.
HAVEN 1 and HAVEN 2 showed that 22 patients underwent 29 surgical procedures: tooth extractions (6), CVAD procedures (9), and other procedures (14). Of the 29 surgical procedures, 9 (31%) were managed with prophylactic bypassing agents, and one treated bleed occurred. At the same time, 20 procedures (69%) were managed without prophylactic bypassing agents, and two treated bleeds occurred.
The researchers concluded that additional studies are needed to inform the use of emicizumab in people with hemophilia A, with and without inhibitor antibodies.
Dr. Callaghan reported having no financial disclosures.
*Correction, 4/26/2018: An earlier version of this story misstated the number of cases of thrombotic microangiopathy.