azd-6244 and Cardiomyopathy--Dilated

Mutations in the LMNA gene encoding A-type nuclear lamins can cause dilated cardiomyopathy with or without skeletal muscular dystrophy. Previous studies have shown abnormally increased extracellular signal-regulated kinase 1/2 activity in hearts of Lmna(H222P/H222P) mice, a small animal model. Inhibition of this abnormal signaling activity with a mitogen-activated protein kinase kinase 1/2 (MEK1/2) inhibitor has beneficial effects on heart function and survival in these mice. However, such treatment has not been examined relative to any standard of care intervention for dilated cardiomyopathy or heart failure. We therefore examined the effects of an angiotensin II converting enzyme (ACE) inhibitor on left ventricular function in Lmna(H222P/H222P) mice and assessed if adding a MEK1/2 inhibitor would provide added benefit.. Male Lmna(H222P/H222P) mice were treated with the ACE inhibitor benazepril, the MEK1/2 inhibitor selumetinib or both. Transthoracic echocardiography was used to measure left ventricular diameters and fractional shortening was calculated.. Treatment of Lmna(H222P/H222P) mice with either benazepril or selumetinib started at 8weeks of age, before the onset of detectable left ventricular dysfunction, lead to statistically significantly increased fractional shortening compared to placebo at 16weeks of age. There was a trend towards a great value for fractional shortening in the selumetinib-treated mice. When treatment was started at 16weeks of age, after the onset of left ventricular dysfunction, the addition of selumetinib treatment to benazepril lead to a statistically significant increase in left ventricular fractional shortening at 20weeks of age.. Both ACE inhibition and MEK1/2 inhibition have beneficial effects on left ventricular function in Lmna(H222P/H222P) mice and both drugs together have a synergistic benefit when initiated after the onset of left ventricular dysfunction. These results provide further preclinical rationale for a clinical trial of a MEK1/2 inhibitor in addition to standard of care in patients with dilated cardiomyopathy caused by LMNA mutations.

Topics: Angiotensin II; Angiotensin-Converting Enzyme Inhibitors; Animals; Benzazepines; Benzimidazoles; Cardiomyopathy, Dilated; Lamin Type A; Male; MAP Kinase Kinase 1; MAP Kinase Kinase 2; Mice; Mutation; Treatment Outcome

Mutations in A-type nuclear lamins gene, LMNA, lead to a dilated cardiomyopathy. We have reported abnormal activation of the extracellular signal-regulated kinase1/2 (ERK1/2) signalling in hearts from Lmna(H222P/H222P) mice, which develop dilated cardiomyopathy. We therefore determined whether an inhibitor of ERK1/2 signalling that has been investigated in clinical trials for cancer has the potential to be translated to humans with LMNA cardiomyopathy.. To evaluate the relevance of this finding in mice to patients, we analysed the ERK1/2 signalling in heart tissue from human subjects with LMNA cardiomyopathy and showed that it was abnormally activated. To determine whether pharmacological inhibitors of the ERK1/2 signalling pathway could potentially be used to treat LMNA cardiomyopathy, we administered selumetinib to male Lmna(H222P/H222P) mice starting at 16 weeks of age, after they show signs of cardiac deterioration, up to 20 weeks of age. Selumetinib is an inhibitor of ERK1/2 signalling and has been given safely to human subjects in clinical trials for cancer. Systemic treatment with selumetinib inhibited cardiac ERK1/2 phosphorylation and blocked increased expression of RNAs encoding natriuretic peptide precursors and proteins involved in sarcomere architecture that occurred in placebo-treated mice. Echocardiography and histological analysis demonstrated that treatment increases cardiac fractional shortening, prevents myocardial fibrosis, and prolongs survival. Selumetinib treatment did not induce biochemical abnormalities suggestive of renal or hepatic toxicity.. Our results suggest that selumetinib or other related inhibitors that have been safely administered to humans in clinical trials could potentially be used to treat LMNA cardiomyopathy.

Topics: Animals; Benzimidazoles; Cardiomyopathy, Dilated; Extracellular Signal-Regulated MAP Kinases; Heart; Humans; Kidney; Lamin Type A; Liver; MAP Kinase Signaling System; Mice; Mutation; Pancreas