ADAs in 20% of monkeys at 25 and 50 mg/kg SC, none at high dose, no exposure effect
“ADAs were observed in 20% of male and female monkeys in the 25 and 50 mg/kg/dose groups, but not in the highest dose groups. No effect on exposure was observed.”
Placental transfer in monkeys: infant drug levels 3.7-fold maternal at postpartum Day 28
“Sibeprenlimab demonstrated placental crossing capability, with infant drug concentrations measuring 3.7-fold higher than maternal levels at postpartum Day 28.”
Pharmacologic immunoglobulin reduction (especially IgA), reversible and without adverse effects in monkeys
“All studies showed the anticipated pharmacological effect, i.e., decreases in immunoglobulin levels (particularly IgA) that were reversible and not associated with any adverse effects on clinical chemistry or histopathology.”
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