GDNF fusion protein dosing was associated with myocarditis.

<p>(A to D) Microphotographs of the heart of monkeys treated with vehicle (A and C) or 5 mg/kg HIRmAb-GDNF (B and D) (H&E staining). The HIRmAb-GDNF-treated animal [rh2134 (B)] shows a moderate multifocal degeneration with interstitial fibrosis (*) and individual myocardiocyte hypertrophy (arrow). Higher-magnification images in (C) and (D) correspond to boxed areas in (A) and (B). Note the presence of lymphocytes, plasma cells, and rare eosinophils in (D). Scale bar: 100 µm (A and B); 25 µm (C and D).