Efficacy and Safety of Mavacamten in Adults with Symptomatic - PowerPoint PPT Presentation

Efficacy and Safety of Mavacamten in Adults with Symptomatic Obstructive Hypertrophic Cardiomyopathy: Results of f the EXPLORER-HCM Study Iacopo Olivotto, MD Azienda Ospedaliera Universitaria Careggi and the University of Florence, Italy On behalf of the EXPLORER-HCM investigators

Declaration of f In Interest Presenting author: • Grant/research support: Sanofi-Genzyme, Shire, Amicus, Bayer, MyoKardia • Honoraria: Sanofi-Genzyme, Shire, Bayer • Consultant: MyoKardia This study was funded by MyoKardia, Inc.

In Introduction • Hypertrophic cardiomyopathy (HCM) is a myocardial disorder characterized by primary left ventricular (LV) hypertrophy • Symptoms are often related to dynamic outflow obstruction • Current medical management for obstructive HCM includes beta-blockers, non-dihydropyridine calcium channel blockers, or disopyramide 1-2 Developing effective pharmacological therapy for obstructive HCM is an important unmet need 1 Elliot PM, et al. Eur Heart J. 2014;35(39): 2733-2779. 2 Gersh BJ, et al. Circulation. 2011;124(24):2761-2796.

Mavacamten: Mechanism of f Action Normal contractility HCM Pathophysiology Attenuated hypercontractility Effective relaxation Hypercontractility Improved compliance Impaired relaxation Improved energetics Altered myocardial energetics Mavacamten is a first-in-class, targeted inhibitor of cardiac myosin  It reduces the number of myosin-actin cross-bridges and thus decreases excessive contractility characteristic of HCM

EXPLORER-HCM Stu tudy Design e HCM 1 Pivot Piv otal Pha Phase 3, 3, Mult ulticenter, , Ra Randomiz ized, , Dou ouble-bli lind, Pla Placebo-controll lled Tria ial l in in Patie tients ts Wit ith Obstr tructive Patients with LVOT gradient ≥50 mmHg and New York Heart Association (NYHA) class II -III symptoms were randomized 1:1 to receive once-daily oral mavacamten (starting dose of 5 mg with a 2-step dose titration) or placebo for 30 weeks Post- Long-Term Screening Double-Blind Placebo-Controlled Treatment Treatment Extension Study 35 days 30 weeks (MAVA-LTE) 8 weeks Mavacamten 2.5, 5, 10, or 15 mg QD Enrolled n=251 Placebo Visits -35d -5d 0 4 6 8 12 14 18 22 26 30 34 38 baseline EOT EOS Starting dose:5 mg QD 10 mg 15 mg 5 mg 10 mg Titration at weeks 8 and 14 2.5 mg 5 mg 2.5 mg 1 Ho CY et al. Circ Heart Fail. 2020; 13(6):e006853

EXPLORER-HCM Endpoints Primary composite functional endpoint Change from baseline to Week 30 pVO 2 NYHA Classification Composite 1 ≥1.5 mL/kg/min and Reduction of ≥1 class EITHER OR Composite 2 ≥3.0 mL/kg/min and No worsening Secondary endpoints included change from baseline to Week 30 in: • Post-exercise LVOT gradient • pVO 2 • Proportion of patients with ≥1 NYHA class improvement • Kansas City Cardiomyopathy Questionnaire-Clinical Summary Score (KCCQ-CSS) • HCM Symptom Questionnaire Shortness-of-Breath (HCMSQ-SoB) subscore Only the primary and secondary endpoints are alpha-controlled

Baseline Demographics and Pati tient Characteristics Mavacamten Placebo Characteristic (N = 123) (N = 128) Age, years, mean ± SD 58.5 ± 12.2 58.5 ± 11.8 Female sex, n (%) 57 (46.3) 45 (35.2) Background HCM therapy, n (%) 94 (76.4) Beta-blocker 95 (74.2) Calcium channel blocker 17 (13.3) 25 (20.3) NYHA functional class, n (%) II 88 (71.5) 95 (74.2) III 35 (28.5) 33 (25.8) History of atrial fibrillation, n (%) 12 (9.8) 23 (18.0) pVO 2, ml/kg/min, mean ± SD 18.9 ± 4.9 19.9 ± 4.9 NT-proBNP, geometric mean (CV%), ng/L* 777 (136) 616 (108) HCM genetic testing performed, n (%) 90 (73.2) 100 (78.1) Pathogenic/likely pathogenic HCM gene 28/90 (31.1) 22/100 (22.0) variant — n/N tested (%) *NT-proBNP: mavacamten, n = 120; placebo, n = 126. HCM, hypertrophic cardiomyopathy; NYHA, New York Heart Association; NT-proBNP, N-terminal pro b-type natriuretic peptide; pVO 2 , peak oxygen consumption.

Baseline Echo Parameters Mavacamten Placebo Echocardiographic parameters, mean ± SD (N = 123) (N = 128) 74 ± 6 74 ± 6 LVEF, % 20 ± 4 20 ± 3 Maximum LV wall thickness, mm 52 ± 29 51 ± 32 LVOT gradient resting, mm Hg 72 ± 32 74 ± 32 LVOT gradient Valsalva, mm Hg 86 ± 34 84 ± 36 LVOT gradient post-exercise, mm Hg* 40 ± 12 41 ± 14 LA volume index, mL/m 2 ‡ *Post-exercise LVOT: mavacamten, n = 122; placebo, n = 127. ‡ LA volume index: mavacamten, n = 123; placebo = 128. LA, left atrial; LV, left ventricular; LVOT, left ventricular outflow tract

Pri rimary Endpoint Mavacamten Placebo Difference (N = 123) (N = 128) (95% CI) n (%) n (%) P value EITHER ≥1.5 ml/kg/min increase in pVO 2 with 19.4 (8.7, 30.1) ≥1 NYHA class improvement OR 45 (36.6) 22 (17.2) 0.0005 ≥3.0 ml/kg/min increase in pVO 2 with no worsening of NYHA class BOTH ≥3.0 ml/kg/min increase in 12.5 (4.0, 21.0) pVO 2 AND ≥1 NYHA class 25 (20.3) 10 (7.8) 0.0005* improvement *P value not alpha-controlled NYHA, New York Heart Association; pVO 2 , peak oxygen consumption.

Se Secondary ry Endpoints Difference* Mavacamten Placebo (95% CI) P value Post-exercise LVOT gradient, n † 117 122 Change from baseline to week 30, mmHg, – 36 ( – 43.2, – 28.1) – 47 ± 40 – 10 ± 30 mean ± SD <0.0001 pVO 2 , n † 120 125 Change from baseline to week 30, 1.35 (0.58, 2.12) 1.40 ± 3.1 – 0.05 ± 3.0 ml/kg/min, mean ± SD 0.0006 ≥1 NYHA class improvement, n† 123 128 Improvement from baseline to week 30, 34 (22.2, 45.4) 80 (65.0) 40 (31.3) n (%) <0.0001 KCCQ-CSS, n † (positive better) 92 88 Change from baseline to week 30, 9.1 (5.5, 12.7) 13.6 ± 14.4 4.2 ± 13.7 mean ± SD <0.0001 HCMSQ-SoB, n † (negative better) 85 86 Change from baseline to week 30, – 1.8 ( – 2.4 to – 1.2) – 2.8 ± 2.7 – 0.9 ± 2.4 mean ± SD <0.0001 *Model estimated least-square mean differences were reported for continuous variables. †N = number analyzable for secondary end point based on N availability of both baseline and week 30 values. HCM Symptom Questionnaire Shortness-of-Breath (HCMSQ-SoB) subscore; Kansas City Cardiomyopathy Questionnaire-Clinical Summary Score (KCCQ-CSS); LVOT, left ventricular outflow tract; NYHA, New York Heart Association; pVO 2 , peak oxygen consumption.

LVOT Gradients and LVEF Over Tim ime Mean (95% CI) post-exercise LVOT gradient Mean (95% CI) LVEF 84,3 100 100 73,4 80 74,2 74,2 mm Hg 75 85,7 60 74.1 70.2 % 50 40 25 20 38,1 0 0 0 30 0 4 6 12 18 22 26 30 Weeks Weeks Mavacamten Placebo Mavacamten Placebo Number of patients at visit Number of patients at visit Mavacamten 122 118 Mavacamten 123 114 116 115 111 111 107 113 Placebo 127 123 128 Placebo 115 117 120 119 121 121 119 Mean (95% CI) resting LVOT gradient Mean (95% CI) Valsalva LVOT gradient 100 80 73,9 51,1 80 62,7 60 45,9 mm Hg mm Hg 60 72,4 40 51,7 40 20 20 24.8 14,1 0 0 0 4 6 12 18 22 26 30 0 4 6 12 18 22 26 30 Weeks Weeks Mavacamten Placebo Mavacamten Placebo Number of patients at visit Number of patients at visit Mavacamten 123 119 119 117 118 116 118 120 Mavacamten 123 117 117 118 118 116 118 120 Placebo 128 121 122 125 122 125 125 123 119 124 Placebo 128 119 125 122 125 124 The dashed lines represent the threshold for guideline-based invasive intervention (post-exercise and Valsalva LVOT gradient >50 mm Hg), the threshold for guideline-based diagnosis of obstruction (resting LVOT gradient <30 mm Hg), or the protocol threshold for temporary discontinuation (LVEF <50%). LVEF, left ventricular ejection fraction; LVOT, left ventricular outflow tract.