Non-neutralizing ADA in ~28% of rats in 3-month study; no ADA in 3-month monkey or 6-month rat studies
“Analysis of plasma samples for antidrug antibody (ADA) detected ADA in a minority of rats (~28%) in the 3-month study found no evidence of marstacimab neutralization (Table 52). There was no evidence of ADA in the 3-month monkey or 6-month rat studies.”
“Therefore, as expected marstacimab binding was noted in endothelial cells one would expect release of TFPI (endothelial cell, placental spongiotrophoblasts, placental trophoblast, islet cells, endocrine epithelium, mesothelium).”
Thrombosis/emboli from TFPI inhibition; minimal lung emboli in healthy animals, risk in hemophilia patients cannot be excluded
“Despite the unclear relationship between lung emboli in healthy animals and marstacimab, the anticipated risk of thrombi/emboli in hemophilia patients cannot be dismissed.”
In vitro whole-blood cytokine release far below alemtuzumab/TGN1412 controls; no effects on monkey TDAR, lymphocyte subsets or serum cytokines; ADA in some monkeys