Fig. 3. Therapeutic efficacy in clinical neonatal calf model of cryptosporidiosis and in vivo safety of EDI048.
a, Schematic representation of a cryptosporidiosis calf model monitoring parasitological and clinical efficacy of EDI048. Calves were orally challenged with 5 × 107 C. parvum oocysts within 48 h of birth. Clinical parameters were assessed every 12 h and parasites shed in faeces were quantified daily by qPCR. Upon onset of diarrhea and detection of oocysts in faeces, calves were treated twice daily with 10 mg kg−1 (body weight) of EDI048 for 7 days. b,c, Compared with vehicle control (open circles), EDI048 (filled circles)-treated calves shed significantly fewer oocysts in faeces (b) and had improved clinical scores of diarrhea (faecal consistency scores) (c). Parasitological and clinical time-course data shown are mean ± s.e.m. of 7 calves tested per group. For AUC analysis, each circle represents an individual calf over 7 days and lines are mean ± s.e.m. of n = 7 calves per group. Statistical analyses were performed using two-tailed unpaired parametric t-tests; **P = 0.0062, ****P < 0.0001. d,e, Dose–exposure–response relationship for EDI048 (d) and compound 6 (e). Mouse exposure at 1, 3 and 10 mg kg−1 d−1 (blue, AUClast), calf exposure at 10 mg kg−1 twice a day (BID) (red, AUC0–12), rat exposures at 50, 250 and 1,000 mg kg−1 d−1 (green, AUC0–8) and dog exposures at 15, 50, 250 and 1,000 mg kg−1 d−1 (purple, AUC0–8) are shown. Overall, efficacy exposures in green and safety exposures in pink zone. 1,000 mg kg−1 d−1 is the NOAEL dose in both rat and dog toxicity study. Exposure multiples for EDI048 is 70× comparing between 1,000 mg kg−1 d−1 NOAEL exposure (day 14) and 10 mg kg−1 d−1 mouse efficacious exposure. f, Schematic representation of Cryptosporidium life cycle and site of action of EDI048 in the GI tract. Orally delivered EDI048 is absorbed by the intestinal cells at the site of infection. Herein, EDI048 demonstrates parasiticidal activity on the intracellular Cryptosporidium parasites by inhibiting membrane biogenesis. The absorbed EDI048 is metabolized in the liver, limiting systemic exposure and thus increasing safety margins.