Generally not immunogenic in monkeys; ADA in 12% including weak responders
“Ipilimumab generally was not immunogenic in monkeys. When including the animals with a weak antibody response, a value of 12% was calculated for the frequency of anti-ipilimumab-Ab positive animals.”
TCR: binding to activated lymphocytes expressing CTLA-4 in human and monkey tissues, and to placental connective tissue
“In tissue cross-reactivity studies, ipilimumab specifically bound to activated lymphocytes expressing CTLA-4 in several normal human and/or cynomolgus monkey tissues. In addition, ipilimumab bound specifically to connective tissue in human and cynomolgus monkey placenta and to connective tissue in cynomolgus monkey ovary; no specific binding was observed in human ovary.”
Immune-related adverse events (colitis, dermatitis) from CTLA-4 blockade; no safety margin determined
“The most notable concern identified during non-clinical testing was a low incidence of serious irAEs, manifested as colitis or dermatitis, for which no safety margin could be determined.”
Anti-ipilimumab antibodies in 12% of monkeys, likely underestimated due to drug interference
“An anti-ipilimumab-antibody response was detected in 12% of the monkeys receiving ipilimumab, although it should be noted that this frequency is likely to be underestimated due to interference of (serum) ipilimumab with the antibody detection assay.”
1.1% of 1024 evaluable patients with unresectable or metastatic melanoma (binding antibodies)
“Eleven (1.1%) of 1024 evaluable patients with unresectable or metastatic melanoma tested positive for treatment-emergent binding antibodies against ipilimumab in an electrochemiluminescent (ECL) based assay.”
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