Prediction of Cardiac ATTR Depletion by NI006 (ALXN2220) Using Mechanistic PK/PD Modeling

NI006 (aka ALXN2220) is a therapeutic antibody candidate in phase III clinical development for the depletion of amyloid transthyretin (ATTR) in patients with ATTR cardiomyopathy, an infiltrative cardiomyopathy leading to increased left ventricular wall thickness (LVWT). The mode-of-action consists in removal of disease-causing amyloid accumulations by activating phagocytic immune cells, a mechanism without precedent in cardiology. To select a safe and potentially efficacious dose range and treatment duration for a combined first-in-human and proof-of-concept clinical phase Ib study, we developed a mechanistic pharmacokinetic and pharmacodynamic (PK/PD) model that can predict NI006 exposure, its effects on cardiac amyloid load and on LWVT, which is a predictor of heart failure in this disease. The PK/PD model predictions supported 0.3 mg/kg monthly dosing as a safe starting dose and identified 10-60 mg/kg monthly as the potentially efficacious dose range with substantial and dose dependent cardiac amyloid burden reduction within 4 months for 60 mg/kg and 10 months for 10 mg/kg. These predictions were in good agreement with the observed primary results of the clinical phase Ib study where amyloid burden was measured by imaging. This novel translational PK/PD model provided important predictions to guide the design of the phase Ib study of NI006, indicating the value of this approach to integrate preclinical results into clinical trial design and increase translational success.