A novel ryanodine receptor 2 inhibitor, M201-A, enhances natriuresis, renal function and lusi-inotropic actions: Preclinical and phase I study.

BACKGROUND AND PURPOSE: The ryanodine receptor 2 (RyR2) is present in both the heart and kidneys, and plays a crucial role in maintaining intracellular Ca2+ homeostasis in cells in these organs. This study aimed to investigate the impact of M201-A on RyR2, as well as studying its effects on cardiac and renal functions in preclinical and clinical studies. EXPERIMENTAL APPROACH: Following the administration of M201-A (1,4-benzothiazepine-1-oxide derivative), we monitored diastolic Ca2+ leak via RyR2 and intracellular Ca2+ concentration in isolated rat cardiomyocytes and in cardiac and renal function in animals. In a clinical study, M201-A was administered intravenously at doses of 0.2 and 0.4 mg·kg-1 once daily for 20 min for four consecutive days in healthy males, with the assessment of haemodynamic responses. KEY RESULTS: In rat heart cells, M201-A effectively inhibited spontaneous diastolic Ca2+ leakage through RyR2 and exhibited positive lusi-inotropic effects on the rat heart. Additionally, it enhanced natriuresis and improved renal function in dogs. In human clinical studies, when administered intravenously, M201-A demonstrated an increase in natriuresis, glomerular filtration rate and creatinine clearance, while maintaining acceptable levels of drug safety and tolerability. CONCLUSIONS AND IMPLICATIONS: The novel drug M201-A inhibited diastolic Ca2+ leak via RyR2, improved cardiac lusi-inotropic effects in rats, and enhanced natriuresis and renal function in humans. These findings suggest that this drug may offer a potential new treatment option for chronic kidney disease and heart failure.

Tumor burden in patients with early and intermediate-stage hepatocellular carcinoma undergoing liver resection: a retrospective multicenter study on clinical and oncological outcomes.

BACKGROUND: According to the Barcelona Clinic Liver Cancer (BCLC) staging system, liver resection (LR) is recommended for early-stage (BCLC-A) hepatocellular carcinoma (HCC) but not for intermediate-stage (BCLC-B). This study aimed to assess the outcomes of LR in these patients using a subclassification tumour burden score (TBS). METHODS: All consecutive patients that underwent LR for BCLC-A and BCLC-B HCC between 01/2010 and 12/2020 in 4 tertiary referral centers were included. Clinical outcomes and overall survival (OS) were assessed in relation to TBS and BCLC stages. RESULTS: Among 612 patients included, 562 were classified as BCLC-A and 50 as BCLC-B. The incidence of overall postoperative complications (56.0 vs 41.5%, p = 0.053) and mortality (0 vs 1.6%, p = 1.000) were similar between BCLC-A and BCLC-B patients. OS was significantly higher for BCLC A/low TBS than BCLC B/low TBS (p = 0.009), while patients with medium and high TBS had similar OS, irrespective of BCLC stage (respectively p = 0.103 and p = 0.343). CONCLUSIONS: Patients with medium and high TBS had comparable OS and DFS, irrespective of BCLC A or B stage, and postoperative morbidity was comparable. These results highlight the need for refinement of the BCLC staging system, and LR could be considered for selected intermediate stage (BCLC-B) according to the tumour burden.

Palmitoylation of the pore-forming subunit of Ca(v)1.2 controls channel voltage sensitivity and calcium transients in cardiac myocytes.

Mammalian voltage-activated L-type Ca2+ channels, such as Ca(v)1.2, control transmembrane Ca2+ fluxes in numerous excitable tissues. Here, we report that the pore-forming α1C subunit of Ca(v)1.2 is reversibly palmitoylated in rat, rabbit, and human ventricular myocytes. We map the palmitoylation sites to two regions of the channel: The N terminus and the linker between domains I and II. Whole-cell voltage clamping revealed a rightward shift of the Ca(v)1.2 current-voltage relationship when α1C was not palmitoylated. To examine function, we expressed dihydropyridine-resistant α1C in human induced pluripotent stem cell-derived cardiomyocytes and measured Ca2+ transients in the presence of nifedipine to block the endogenous channels. The transients generated by unpalmitoylatable channels displayed a similar activation time course but significantly reduced amplitude compared to those generated by wild-type channels. We thus conclude that palmitoylation controls the voltage sensitivity of Ca(v)1.2. Given that the identified Ca(v)1.2 palmitoylation sites are also conserved in most Ca(v)1 isoforms, we propose that palmitoylation of the pore-forming α1C subunit provides a means to regulate the voltage sensitivity of voltage-activated Ca2+ channels in excitable cells.