No cytokine release (IL-2) from hPBMCs cultured on immobilized pembrolizumab
“Pembrolizumab was evaluated in a cytokine release assay there was no evidence of cytokine release, as assessed by IL-2 production following culture of hPBMCs in pembrolizumab-immobilized (air-dried) plates.”
✓ VerifiedFDA pharmacology/toxicology review, p. 13Source ↗
Biodistribution & persistence
Vss 30.9-54.8 mL/kg in monkeys, similar to plasma volume; limited distribution out of plasma
“the Vss mean value (30.9, 36.8, 54.8 ml/kg) was similar to the plasma volume of monkeys suggesting that pembrolizumab has a limited distribution out of the plasma compartment”
Autoimmune adverse events secondary to the drug's pharmacological action
“In patients that receive pembrolizumab, autoimmune diseases are the most common adverse events, and are likely secondary to the pharmacological actions of the drug.”
✓ VerifiedFDA pharmacology/toxicology review, p. 14Source ↗
Anti-drug antibodies: animals
6-month monkey: ADA in 5 animals at 6 mg/kg and 1 at 200 mg/kg, increasing pembrolizumab elimination; drug interference at higher doses
“Anti-pembrolizumab antibodies were detected in 5 animals of the 6 mg/kg group (during the dosing period) and in 1 animal in the 200 mg/kg group (during the recovery period) and were associated with an increase in elimination of pembrolizumab.”
1.4% (3/211) developed anti-pembrolizumab antibodies (subcutaneous KEYTRUDA QLEX); one with neutralizing antibodies
“With a median (min, max) duration of treatment on KEYTRUDA QLEX of 6.9 months (1 day, 1 year) in Study MK-3475A-D77, 1.4% (3/211) of patients developed anti-pembrolizumab antibodies, and one ADA-positive patient developed neutralizing antibodies (NAb) against pembrolizumab.”
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