CAMZYOS® Study Designs for EXPLORER-HCM and EXPLORER-LTE
EXPLORER-HCM: A Groundbreaking Phase 3 Trial for
Symptomatic NYHA Class II–III Obstructive HCM1,2
A randomized, double blind, placebo-controlled trial evaluated the efficacy and safety of CAMZYOS vs placebo1,2
5-week
screening phase1,2
Select inclusion criteria1,2
- ≥18 years old, body weight >45 kg at screening
- NYHA class II or III
- Diagnosis of obstructive HCM
- Left ventricular ejection fraction (LVEF) ≥55%
- LVOT ≥50 mmHg at rest or with provocation
- Able to safely perform upright cardiopulmonary
exercise testing (CPET)
Select exclusion criteria1,2
- Known infiltrative or storage disorder that mimics
obstructive HCM (Fabry disease, amyloidosis, or
Noonan syndrome with left ventricular hypertrophy)
- Underwent SRT within 6 months prior to screening or
plans to have SRT during the study
- Treatment (within 14 days prior to screening) or planned
treatment with disopyramide, ranolazine, or a
combination of beta blockers (BBs) and calcium channel
blockers (CCBs); prior treatment with cardiotoxic agents
CAMZYOS(n=123)
Randomized 1:1 (N=251)2
Placebo(n=128)
30-week
treatment phase1,2
CAMZYOS and placebo were administered orally, once a day. Dosage was monitored and adjusted (as needed) at weeks 8 and 14 to optimize patient response (decrease in LVOT gradient with Valsalva maneuver), maintain LVEF ≥50%, and was further informed by plasma concentrations of CAMZYOS
8-week washout phase1,2
Study drug was discontinued and participants returned for key assessments at week 38
The primary composite functional endpoint and hierarchical secondary endpoints
were designed to assess treatment parameters for symptomatic NYHA class II–III
obstructive HCM2
Primary composite functional endpoint measured change from baseline to week 30 in symptoms (NYHA) and functional
capacity (pVO2)1,2
≥1 NYHA class improvement
AND
≥1.5 mL/kg/min improvement in pVO2
OR
No worsening in NYHA class
AND
≥3.0 mL/kg/min improvement in pVO2
Hierarchical secondary endpoints1,2†:(Measured from baseline to week 30)
- Change in post-exercise LVOT gradient
- Change in pVO2
- Proportion of patients with ≥1 NYHA
class improvement
- Change in KCCQ-23–CSS
- Change in HCMSQ-SoB
Select prespecified exploratory endpoints1,2:(Not powered for statistical significance)
- Post-exercise LVOT peak gradient <50 mmHg
- Post-exercise LVOT peak gradient <30 mmHg
- Proportion of patients with reductions in serum concentrations
of N-terminal pro B-type natriuretic peptide (NT-proBNP) and
high-sensitivity cardiac troponin I (hs-cTnI)
- †All assessments for secondary endpoints were
performed and Type I error was controlled in
hierarchical order (sequence as indicated above)
upon achieving significance in the primary endpoint
(with two-tailed P<0.05 required to proceed).2
Select baseline patient characteristics in EXPLORER-HCM1,2
Select baseline patient characteristics
Values in the table are mean ± SD, n (%) |
CAMZYOS (n=123) |
Placebo (n=128) |
Age, mean (SD), years |
59 (12.2) |
59 (11.8) |
Women, n (%) |
57 (46) |
45 (35) |
Race, n (%) |
White
Black or African American
American Indian or Alaska Native
Asian
Unknown
|
115 (94)
1 (1)
0
4 (3)
3 (2)
|
114 (89)
5 (4)
1 (1)
2 (2)
6 (5)
|
Background HCM treatment, n (%) |
Beta blocker
Calcium channel blocker‡
|
94 (76)
25 (20)
|
95 (74)
17 (13)
|
NYHA class, n (%) |
Class II
Class III
|
88 (72)
35 (28)
|
95 (74)
33 (26)
|
pVO2 mean (SD), mL/kg/min |
18.9 (4.9) |
19.9 (4.9) |
LVOT gradient at baseline, mean (SD), mmHg |
Valsalva
Post-exercise§
|
72 (32)
86 (34)
|
74 (32)
84 (36)
|
LVEF, mean (SD), (%) |
74 (6) |
74 (6) |
Critical cardiac history |
Atrial fibrillation, n (%)
Implantable cardioverter- defibrillator, n (%)
Prior invasive SRT, n (%)
|
12 (10)
27 (22)
11 (9)
|
23 (18)
29 (23)
8 (6)
|
- ‡Nondihydropyridine calcium channel blockers.2
- §Data missing for one patient in the CAMZYOS group and one patient in the placebo group.2
Study procedures used
in EXPLORER-HCM1
|
Assessment |
Parameters Tested |
Echocardiography
Echocardiography
All echocardiographic parameters were acquired by study- certified sonographers at clinical sites and read from transthoracic two-dimensional (2D) echocardiography at the Cardiovascular Imaging Core Laboratory (CICL), Boston, MA, according to the study-specific echo analysis protocol.
- Maximum left
ventricular wall thickness
- LV volumes and
ejection fraction
- LA volume
- Peak instantaneous
LVOT gradient
- Mitral inflow velocity
profile
- Mitral annular (e’)
velocity
Cardiopulmonary exercise testing (CPET)
Cardiopulmonary exercise testing (CPET)
CPET was conducted using a standardized treadmill or bicycle ergometer at screening and at week 30 prior to study drug dosing.
The same modality (treadmill or upright bicycle) had to be used for all CPETs conducted for a given participant.
CPET data were sent to a central laboratory for review and interpretation according to study- specific procedure manual.
- VO2
- Percentage predicted
VO2
- Carbon dioxide
production (VCO2)
- Expired ventilation
(VE)
- VE/VO2 ratio
- Ventilatory efficiency
(VE/VCO2 slope)
- RER
- Circulatory power
(peak VO2/peak SBP)
- Metabolic equivalents
achieved (METs)
- O2 pulse at peak
exercise
- End tidal CO2
Electrocardiogram (ECG)
Electrocardiogram (ECG)12-lead ECGs were transmitted to a central laboratory, ERT, for reading and interpretation.
Holter
HolterAfter data collection, the memory card was analyzed by a central laboratory, ERT, for continuous ECG waveforms.
- 48-hour continuous
Holter monitoring
Accelerometry2
Accelerometry2Recording of daily physical activity using a wrist-worn accelerometer was performed at baseline and end of treatment.
- Wrist-worn, 3-axis
accelerometer
Biomarkers3
Biomarkers3Serum concentrations of N-terminal pro B- type natriuretic peptide (NT-proBNP) and high-sensitivity cardiac troponin I (hs-cTnI).
- Blood collection for
genotyping (optional) and future exploratory analyses
Cardiac magnetic resonance (CMR)
Cardiac magnetic resonance (CMR)CMR acquisition took place at equipped sites and submitted to a central laboratory.
- Measures of cardiac
structure and function
CO2=carbon dioxide; LA=left atrial; LV=left ventricular; LVOT=left ventricular outflow tract; O2=oxygen; peak VO2=peak oxygen consumption; RER=respiratory exchange ratio; SBP=systolic blood pressure.
|
References:
- Ho CY, Olivotto I, Jacoby D, et al. Study
design and rationale of EXPLORER-HCM:
evaluation of mavacamten in adults with
symptomatic obstructive hypertrophic
cardiomyopathy. Circ Heart Fail.
2020;13(6):e006853 [supplementary
appendix].
- Ho CY, Olivotto I, Jacoby D, et al. Study
design and rationale of EXPLORER-HCM:
evaluation of mavacamten in adults with
symptomatic obstructive hypertrophic
cardiomyopathy. Circ Heart Fail.
2020;13(6):e006853.
- Olivotto I, Oreziak A, Barriales-Villa R, et al;
EXPLORER-HCM study investigators.
Mavacamten for treatment of symptomatic
obstructive hypertrophic cardiomyopathy
(EXPLORER-HCM): a randomised, double-
blind, placebo-controlled, phase 3 trial.
Lancet. 2020;396(10253):759-769.
Primary composite
functional endpoint
explained
The primary goal of EXPLORER-HCM was to understand how CAMZYOS® could improve exercise capacity and symptom burden.1
The primary composite functional endpoint, assessed at 30 weeks, was defined as the proportion of patients who achieved either improvement of peak oxygen consumption (pVO2) by ≥1.5 mL/kg/min plus improvement in NYHA class by at least 1 or improvement of pVO2 by ≥3.0 mL/kg/min plus no worsening in NYHA class.2
Exercise capacity was assessed with pVO2, which is an objective measure of peak oxygen consumption during cardiopulmonary exercise testing and has been shown to correlate with NYHA class.1*
Symptoms were assessed with NYHA class, which is a subjective measure of symptom burden.1
Data are based on all randomized patients who received ≥1 dose of study treatment. Missing NYHA class data at week 30 were imputed with the week 26 value. Patients with a nonevaluable primary endpoint were considered nonresponders. pVO2 was analyzed with all available data without imputation.3
NYHA functional
classifications4
Class
Patient Symptoms
-
I
No symptoms or exercise limitations
-
II
Mild symptoms and some exercise limitations
-
III
Noticeable symptoms with minimal physical activity; comfortable only at rest
-
IV
Severe symptoms while at rest
References:
- Ho CY, Olivotto I, Jacoby D, et al. Study design and rationale of EXPLORER-HCM: evaluation of mavacamten in adults with symptomatic obstructive hypertrophic cardiomyopathy. Circ Heart Fail. 2020;13(6):e006853.
- CAMZYOS [package insert]. Princeton, NJ: Bristol-Myers Squibb Company; 2023.
- Olivotto I, Oreziak A, Barriales-Villa R, et al; EXPLORER-HCM study investigators. Mavacamten for treatment of symptomatic obstructive hypertrophic cardiomyopathy (EXPLORER-HCM): a randomised, double-blind, placebo-controlled, phase 3 trial. Lancet. 2020;396(10253):759-769.
- Burstein Waldman C, Owens A. A plain language summary of the EXPLORER-HCM study: mavacamten for obstructive hypertrophic cardiomyopathy. Future Cardiol. 2021;17(7):1269-1275. doi:10.2217/fca-2021-0044
EXPLORER-LTE: A Cohort of MAVA-LTE, a 5-Year Extension Designed to Evaluate Long-Term Safety, Efficacy, and Clinically Guided Dosing for CAMZYOS3,4
To be eligible to enroll in the EXPLORER-LTE cohort of MAVA-LTE, patients had to complete EXPLORER-HCM, including the 8-week washout period. Of the 251 patients|| who completed EXPLORER-HCM, 231 enrolled in MAVA-LTE in the EXPLORER-LTE cohort, which is being evaluated in a single-arm trial without an active comparator.
- ||Patients enrolled in EXPLORER-LTE were part of either the CAMZYOS or placebo arm in the EXPLORER-HCM trial.3-5
- ¶This is not consistent with the current approved dosing schedule per the U.S. Full Prescribing Information.1
MAVA-LTE: EXPLORER-LTE cohort study limitations and additional information:
- These data are not included in the CAMZYOS U.S. Full Prescribing Information. Caution should be used in interpreting the data as data were not statistically tested for significance but are only descriptive in nature4
- MAVA-LTE, including the EXPLORER-LTE cohort, is a single-arm study without active comparator; patients in EXPLORER-LTE were part of either the CAMZYOS or placebo group in EXPLORER-HCM; therefore, baseline characteristics for EXPLORER-LTE changed due to time and consolidation of both arms to one cohort5
- There are limitations with the data, including decreased sample size and different continuation rates based on the continued involvement of responders and attrition of nonresponders5
- The EXPLORER-LTE cohort of MAVA-LTE included 14 patients who were NYHA class I at screening. These patients were included in the EXPLORER-HCM trial; 5 had received CAMZYOS, and 9 were in the placebo group3
Select Patient Baseline# Characteristics for EXPLORER-LTE3
- #Baseline is defined as last non-missing measurement before the first dose of CAMZYOS in MAVA-LTE.3
- **14 patients improved from NYHA class II–III to NYHA class I between EXPLORER-HCM baseline and MAVA-LTE baseline.3
Interim analysis from EXPLORER-LTE
Change in CAMZYOS Dose During the Treatment Period3
Change in dose distribution from baseline††
At the end of Week 30 in EXPLORER-HCM, 49% of patients were taking the 5-mg dose, 33% were taking the 10-mg dose, and 11% were receiving the 15-mg dose.1