Prolonged B-cell depletion; incomplete B-cell recovery 90 days post dose, low animal exposure, no long-term studies
“The major concerns were the low level of exposure in Cynomolgus as compared to human level of exposure (1:1) and the lack of long-term animal studies, since B-cell recovery was not complete 90 days post dose.”
Anti-rituximab antibodies in monkeys may appear after 2 weeks, making long-term study results inconclusive
“In long-term administration studies the problem of immunogenicity of rituximab in Cynomolgus could make the results inconclusive. Antibodies against rituximab may appear after 2 weeks of treatment.”
1.1% (4/356) in low-grade/follicular NHL; 11% (273/2578) in RA
“Using an ELISA assay, anti-rituximab antibody was detected in 4 of 356 (1.1%) patients with low-grade or follicular NHL receiving single-agent RITUXAN. Three of the four patients had an objective clinical response. A total of 273/2578 (11%) patients with RA tested positive for anti-rituximab antibodies at any time after receiving RITUXAN.”
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