SpeciesAcceptedBeyond the letter
No pharmacologically relevant species; repeat-dose and DART toxicology done only with a mouse-specific surrogate antibody (BI674304)
Why: Surrogate shows binding and functional activity comparable to spesolimab · No relevant species · Pharmacology or kinetics
“Given that spesolimab and its surrogate BI674304 show comparable binding and functional activity, the use of BI674304 as a suitable surrogate to evaluate potential effects of IL36 antagonism in toxicology studies mice is agreed. This strategy was also endorsed by CHMP.”
✓ VerifiedEMA assessment report, p. 33Source ↗ Safety marginAcceptedBeyond the letter
No exposure margins to clinical exposure calculable for the surrogate; NOAEL exposures compared with in vitro IC90 values instead
Why: Toxicology study exposures exceeded the surrogate's IC90 values in primary mouse cells · Pharmacology or kinetics
“Further, based on IC90-values of BI674304 to inhibit mouse IL36α, β or γ-induced IL-2 and IFNγ cytokine production or NFκB phosphorylation in primary mouse cells (3.8-18 nM corresponding to 0.57-2.68 µg/mL), the exposures in the toxicology studies were higher. Thus, sufficient exposures have been reached in the studies.”
✓ VerifiedEMA assessment report, p. 35Source ↗ CarcinogenicityAcceptedBeyond the letter
No carcinogenicity studies; weight-of-evidence assessment instead
Why: Not active in rodents; 6-month surrogate study, literature on IL36R and clinical data give no reason for concern · No relevant species · Weight of evidence
“Spesolimab is not pharmacologically active in rodents (or any other relevant species) why no meaningful data would be generated in long-term carcinogenicity studies. Therefore, an evaluation of the potential carcinogenicity risk of spesolimab has been performed using a weight-of-evidence (WoE) approach.”
✓ VerifiedEMA assessment report, p. 30Source ↗ “Regarding carcinogenesis, based on data from the 6-month general toxicity study of BI 674304 in mice, scientific literature on the potential role of IL36R in tumor promotion, and clinical data from spesolimab clinical trials, there are no concrete reasons to believe that inhibition of IL36R by spesolimab would lead to carcinogenicity. The Executive Carcinogenicity Assessment committee (ECAC) concurred with this conclusion.”
✓ VerifiedFDA multi-discipline review, p. 36Source ↗ Safety pharmacologyVerdict not stated
No stand-alone safety pharmacology studies and no safety pharmacology endpoints embedded in repeat-dose studies
Why: No respiratory or neurobehavioral signs in mouse toxicity studies
“Stand-alone safety pharmacology studies were not conducted. Safety pharmacology studies were not embedded in the repeat-dose toxicity studies. However, no treatment-related organ toxicities or clinical signs indicative of respiratory or neurobehavioral effects were observed in mice”
✓ VerifiedFDA multi-discipline review, p. 37Source ↗