Hbbth3/+ β-thalassemia mouse (another hemolytic anemia), normal mice, and RBCs from PKD patients ex vivo
“The Applicant stated that in vivo studies were conducted in normal C57BL/6 mice and in the murine Hbbth3/+ model of β-thalassemia, another hemolytic anemia, because suitable animal models of PKD were not available during the early development of mitapivat.”
No suitable animal model of PK deficiency available; β-thalassemia mouse used instead
“The Applicant stated that in vivo studies were conducted in normal C57BL/6 mice and in the murine Hbbth3/+ model of β-thalassemia, another hemolytic anemia, because suitable animal models of PKD were not available during the early development of mitapivat.”
FDA: no in vivo PKD model, but thalassemia mouse, ex vivo data and mechanism give sufficient evidence of potential effectiveness
“Although a proof-of-concept from an in vivo model of PKD was not conducted, the beneficial effect of mitapivat on RBC in the mouse model of thalassemia, combined with the ex vivo studies with PK isoforms, and pharmacological rationale (i.e., allosteric activation of a deficient PK enzyme) provides sufficient evidence of potential effectiveness in treating PKD.”