Rapid CSF-to-CNS tissue distribution with transfer to systemic circulation; long CSF/CNS half-life (20-45 days, monkey)
“The rapid distribution phase is due to the rapid and broad distribution from the CSF to the CNS tissues with additional clearance due to transfer to the systemic circulation.”
CNS: neuronal vacuolation and transient neurological signs after IT ASO; class thrombocytopenia/renal risks considered
“In monkeys, IT administration of 0, 4, 12, and 35 mg tofersen in male and female cynomolgus monkeys every other week for 9 months resulted in histologic findings of neuronal vacuolation at all doses; however, vacuolation was not accompanied by neurodegeneration and was not present in recovery groups.”
58.4% (97 patients) treatment-emergent ADA, 83 persistent; ADA decreased plasma tofersen clearance by 32%
“Overall, 97 QALSODY-treated patients (58.4%) developed treatment-emergent ADAs, of which 14 were transient and 83 were persistent. The presence of anti-drug antibodies (ADA) appeared to decrease plasma tofersen clearance by 32%.”
Main pharmacology-related risk is increased susceptibility to infections (C5 inhibition); no complement activation by the aptamer in monkeys; panuveitis with Lucentis combination