PMID- 37639259 OWN - NLM STAT- MEDLINE DCOM- 20231012 LR - 20240501 IS - 2380-6591 (Electronic) IS - 2380-6583 (Print) VI - 8 IP - 10 DP - 2023 Oct 1 TI - Effect of Mavacamten on Chinese Patients With Symptomatic Obstructive Hypertrophic Cardiomyopathy: The EXPLORER-CN Randomized Clinical Trial. PG - 957-965 LID - 10.1001/jamacardio.2023.3030 [doi] AB - IMPORTANCE: Mavacamten has shown clinical benefits in global studies for patients with obstructive hypertrophic cardiomyopathy (oHCM), but evidence in the Asian population is lacking. OBJECTIVE: To evaluate the safety and efficacy of mavacamten compared with placebo for Chinese patients with symptomatic oHCM. DESIGN, SETTING, AND PARTICIPANTS: This phase 3, randomized, double-blind, placebo-controlled clinical trial was conducted at 12 hospitals in China. Between January 4 and August 5, 2022, patients with oHCM and a left ventricular outflow tract (LVOT) gradient of 50 mm Hg or more and New York Heart Association (NYHA) class II or III symptoms were enrolled and received treatment for 30 weeks. INTERVENTIONS: Patients were randomized 2:1 to receive mavacamten (starting at 2.5 mg once daily) or placebo for 30 weeks. MAIN OUTCOMES AND MEASURES: The primary end point was change in Valsalva LVOT peak gradient from baseline to week 30. Left ventricular outflow tract gradients and left ventricular ejection fraction (LVEF) were assessed by echocardiography, while left ventricular mass index (LVMI) was determined by cardiac magnetic resonance imaging. Analysis was performed on an intention-to-treat basis. RESULTS: A total of 81 patients (mean [SD] age, 51.9 [11.9] years; 58 men [71.6%]) were randomized. Mavacamten demonstrated a significant improvement in the primary end point compared with placebo (least-squares mean [LSM] difference, -70.3 mm Hg; 95% CI, -89.6 to -50.9 mm Hg; 1-sided P < .001). Similar trends were demonstrated for resting LVOT peak gradient (LSM difference, -55.0 mm Hg; 95% CI, -69.1 to -40.9 mm Hg). At week 30, more patients receiving mavacamten than placebo achieved a Valsalva LVOT peak gradient less than 30 mm Hg (48.1% [26 of 54] vs 3.7% [1 of 27]), less than 50 mm Hg (59.3% [32 of 54] vs 7.4% [2 of 27]), and NYHA class improvement (59.3% [32 of 54] vs 14.8% [4 of 27]). Greater improvements were also observed with mavacamten regarding the Kansas City Cardiomyopathy Questionnaire Clinical Summary Score (LSM difference, 10.2; 95% CI, 4.4-16.1), N-terminal pro-B-type natriuretic peptide level (proportion of geometric mean ratio, 0.18; 95% CI, 0.13-0.24), high-sensitivity cardiac troponin I level (proportion of geometric mean ratio, 0.34; 95% CI, 0.27-0.42), and LVMI (mean difference, -30.8 g/m2; 95% CI, -41.6 to -20.1 g/m2). Safety and tolerability were similar between mavacamten and placebo. No patients experienced LVEF less than 50%. CONCLUSIONS: Mavacamten significantly improved Valsalva LVOT gradient vs placebo for Chinese patients. All secondary efficacy end points were also improved. Mavacamten was well tolerated with no new safety signals. This study supports the efficacy and safety of mavacamten in diverse populations, including Chinese patients. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT05174416. FAU - Tian, Zhuang AU - Tian Z AD - Department of Cardiology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China. FAU - Li, Liwen AU - Li L AD - Department of Cardiology, Guangdong Cardiovascular Institute, Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, Southern Medical University, Guangzhou, Guangdong Province, China. FAU - Li, Xiaoyan AU - Li X AD - Department of Cardiology, Renmin Hospital of Wuhan University, Hubei General Hospital, Wuhan, Hubei Province, China. FAU - Wang, Jian'an AU - Wang J AD - Department of Cardiology, the Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, Zhejiang Province, China. FAU - Zhang, Qing AU - Zhang Q AD - Department of Cardiology, West China Hospital, Sichuan University, Chengdu, Sichuan Province, China. FAU - Li, Zhanquan AU - Li Z AD - Department of Cardiology, the People's Hospital of Liaoning Province, Shenyang, Liaoning Province, China. FAU - Peng, Daoquan AU - Peng D AD - Department of Cardiology, the Second Xiangya Hospital of Central South University, Changsha, Hunan Province, China. FAU - Yang, Ping AU - Yang P AD - Department of Cardiology, China-Japan Union Hospital of Jilin University, Changchun, Jilin Province, China. FAU - Ma, Wei AU - Ma W AD - Department of Cardiology, Peking University First Hospital, Beijing, China. FAU - Wang, Fang AU - Wang F AD - Department of Cardiology, Beijing Hospital, National Center of Gerontology, Institute of Geriatric Medicine, Chinese Academy of Medical Sciences, Beijing, China. FAU - Jin, Wei AU - Jin W AD - Department of Cardiology, Ruijin Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China. FAU - Cheng, Xiang AU - Cheng X AD - Department of Cardiology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei Province, China. FAU - Sun, Jing AU - Sun J AD - Shanghai LianBio Development Co, Ltd, Shanghai, China. FAU - Fu, Yiqun AU - Fu Y AD - Shanghai LianBio Development Co, Ltd, Shanghai, China. FAU - Lyu, Cheng AU - Lyu C AD - Shanghai LianBio Development Co, Ltd, Shanghai, China. FAU - Zhang, Shuyang AU - Zhang S AD - Department of Cardiology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China. LA - eng SI - ClinicalTrials.gov/NCT05174416 PT - Comment PT - Journal Article PL - United States TA - JAMA Cardiol JT - JAMA cardiology JID - 101676033 RN - 0 (MYK-461) SB - IM CON - JAMA Cardiol. 2023 Oct 1;8(10):966-967. PMID: 37639265 EIN - JAMA Cardiol. 2024 May 1;:. PMID: 38691370 MH - Male MH - Humans MH - Middle Aged MH - Stroke Volume/drug effects MH - *Ventricular Function, Left/drug effects MH - Double-Blind Method MH - East Asian People MH - *Cardiomyopathy, Hypertrophic/drug therapy/physiopathology PMC - PMC10463173 COIS- Conflict of Interest Disclosures: Drs Sun, Fu, and Lyu are employees of Shanghai LianBio Development Co, Ltd. No other disclosures were reported. EDAT- 2023/08/28 12:43 MHDA- 2023/10/12 06:43 PMCR- 2023/08/28 CRDT- 2023/08/28 11:33 PHST- 2023/10/12 06:43 [medline] PHST- 2023/08/28 12:43 [pubmed] PHST- 2023/08/28 11:33 [entrez] PHST- 2023/08/28 00:00 [pmc-release] AID - 2809051 [pii] AID - hoi230044 [pii] AID - 10.1001/jamacardio.2023.3030 [doi] PST - ppublish SO - JAMA Cardiol. 2023 Oct 1;8(10):957-965. doi: 10.1001/jamacardio.2023.3030.