Transient impairment of primary anti-KLH IgG response (TDAR) in monkeys; robust response after second challenge
“Emapalumab transiently impaired monkey’s capacity to mount a primary anti-Keyhole Limpet Hemocyanin (KLH) IgG response 14 days after the first KLH challenge; however, a robust IgG response was observed in all monkeys 21 days after the second KLH challenge.”
✓ VerifiedFDA multi-discipline review, p. 24Source ↗
Biodistribution & persistence
No cross-reactivity with the human tissues tested
“Emapalumab did not induce in vitro antibody-dependent cell cytotoxicity (ADCC) or complement-dependent cytotoxicity (CDC) activity and it did not cross-react with a variety of human tissues tested.”
✓ VerifiedFDA multi-discipline review, p. 23Source ↗
Modality-specific risk
Increased infection susceptibility from IFN-γ neutralization
“An increase in susceptibility to infection as consequence of an exaggerated immunomodulating (pharmacological) effect of emapalumab can’t be ruled out, since IFNγ neutralization favors infections.”
✓ VerifiedFDA multi-discipline review, p. 24Source ↗
Anti-drug antibodies: animals
Not detected in the 13-week monkey study; inconclusive due to possible drug interference
“Anti-drug antibodies were not detected; however, the results are inconclusive due possible interference of the drug itself.”
✓ VerifiedFDA multi-discipline review, p. 38Source ↗
Anti-drug antibodies: patients
Treatment-emergent ADA in 3% (1/33) of primary HLH patients (neutralizing) and 14% (5/35) in HLH/MAS trials (non-neutralizing)
“Treatment-emergent anti-drug antibodies (ADAs) were detected in 1/33 (3%) of patients in the primary HLH clinical trial. The ADAs in this patient were found to have neutralizing ability. Treatment-emergent ADAs were detected in 5/35 patients (14%) in the two HLH/MAS clinical trials. None of the ADAs in these 5 patients were found to have neutralizing ability.”
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