Antisense Therapy Attenuates Phospholamban p.(Arg14del) Cardiomyopathy in Mice and Reverses Protein Aggregation

Inherited cardiomyopathy caused by the p.(Arg14del) pathogenic variant of the phospholamban (PLN) gene is characterized by intracardiomyocyte PLN aggregation and can lead to severe dilated cardiomyopathy. We recently reported that pre-emptive depletion of PLN attenuated heart failure (HF) in several cardiomyopathy models. Here, we investigated if administration of a Pln-targeting antisense oligonucleotide (ASO) could halt or reverse disease progression in mice with advanced PLN-R14del cardiomyopathy. To this aim, homozygous PLN-R14del (PLN-R14 (Δ/Δ)) mice received PLN-ASO injections starting at 5 or 6 weeks of age, in the presence of moderate or severe HF, respectively. Mice were monitored for another 4 months with echocardiographic analyses at several timepoints, after which cardiac tissues were examined for pathological remodeling. We found that vehicle-treated PLN-R14 (Δ/Δ) mice continued to develop severe HF, and reached a humane endpoint at 8.1 ± 0.5 weeks of age. Both early and late PLN-ASO administration halted further cardiac remodeling and dysfunction shortly after treatment start, resulting in a life span extension to at least 22 weeks of age. Earlier treatment initiation halted disease development sooner, resulting in better heart function and less remodeling at the study endpoint. PLN-ASO treatment almost completely eliminated PLN aggregates, and normalized levels of autophagic proteins. In conclusion, these findings indicate that PLN-ASO therapy may have beneficial outcomes in PLN-R14del cardiomyopathy when administered after disease onset. Although existing tissue damage was not reversed, further cardiomyopathy progression was stopped, and PLN aggregates were resolved

Early Clinical Experience With AZD4831, A Novel Myeloperoxidase Inhibitor, Developed for Patients With Heart Failure With Preserved Ejection Fraction

We evaluated safety, tolerability, pharmacokinetics (PKs), and pharmacodynamics of AZD4831, a novel oral myeloperoxidase (MPO) inhibitor, in a randomized, single‐blind, placebo‐controlled study, following once‐daily multiple ascending dosing to steady‐state in healthy subjects. Target engagement was measured as specific MPO activity in plasma following ex vivo zymosan stimulation of whole blood. Except for generalized maculopapular rash in 4 of 13 subjects receiving the 2 highest doses, 15 and 45 mg AZD4831, no clinically relevant safety and tolerability findings were observed. AZD4831 was rapidly absorbed and plasma concentrations declined slowly with an elimination half‐life of ~ 60 hours. A dose/concentration‐effect relationship between MPO inhibition vs. AZD4831 exposure was established with > 50% MPO inhibition in plasma at concentrations in the low nanomolar range. Steady‐state levels were achieved within 10 days. Taken together, the PK profile, the sustained dose/concentration‐dependent MPO inhibition, and available clinical data support further clinical development of AZD4831 in patients with heart failure with preserved ejection fraction