Effect of Mavacamten in Women Compared With Men With Obstructive Hypertrophic Cardiomyopathy: Insights From EXPLORER-HCM.

BACKGROUND: Compared with men, women with hypertrophic cardiomyopathy (HCM) have a higher incidence of heart failure and worse outcomes. We investigated baseline clinical and echocardiographic characteristics and response to mavacamten among women compared with men in the EXPLORER-HCM study (Clinical Study to Evaluate Mavacamten [MYK-461] in Adults With Symptomatic Obstructive Hypertrophic Cardiomyopathy). METHODS: A prespecified post hoc analysis of sex from the blinded, randomized EXPLORER-HCM trial of mavacamten versus placebo in symptomatic patients with obstructive HCM was performed. Baseline characteristics were compared with t tests for continuous variables (expressed as mean values) and χ2 tests for categorical variables. Prespecified primary, secondary, and exploratory end points and echocardiographic measurements from baseline to end of treatment (week 30) were analyzed with ANCOVA for continuous end points and a generalized linear model with binomial distribution for binary end points, with adjustment for each outcome's baseline value, New York Heart Association class, ß-blocker use, and ergometer type. RESULTS: At baseline, women (n=102) were older (62 years versus 56 years; P<0.0001), had lower peak oxygen consumption (16.7 mL·kg-1·min-1 versus 21.3 mL·kg-1·min-1; P<0.0001), were more likely to be assigned New York Heart Association class III (42% versus 17%; P<0.0001), had worse health status (Kansas City Cardiomyopathy Questionnaire-Clinical Summary Score 64 versus 75; P<0.0001), and had higher baseline plasma NT-proBNP (N-terminal pro-B-type natriuretic peptide) levels (1704 ng/L versus 990 ng/L; P=0.004) than men (n=149). After 30 weeks of mavacamten treatment, similar improvements were observed in women and men in the primary composite end point (percentage difference on mavacamten versus placebo, 22% versus 19%, respectively; P=0.759) and in the secondary end points of change in postexercise left ventricular outflow tract gradient (-42.4 mm Hg versus -33.6 mm Hg; P=0.348), change in peak oxygen consumption (1.2 mL·kg-1·min-1 versus 1.6 mL·kg-1·min-1; P=0.633), and percentage achieving ≥1 New York Heart Association class improvement (41% versus 28%; P=0.254). However, women had greater improvement in health status (Kansas City Cardiomyopathy Questionnaire-Clinical Summary Score 14.8 versus 6.1; P=0.026) and in the exploratory end point of NT-proBNP levels (-1322 ng/L versus -649 ng/L; P=0.0008). CONCLUSIONS: Although at baseline women with symptomatic obstructive HCM enrolled in EXPLORER-HCM were older and had worse heart failure and health status than men, treatment with mavacamten resulted in similar improvements in the primary and most secondary EXPLORER-HCM end points and greater improvements in health status and NT-proBNP. REGISTRATION: URL: https://www.clinicaltrials.gov; Unique identifier: NCT03470545.

Dose-Blinded Myosin Inhibition in Patients With Obstructive Hypertrophic Cardiomyopathy Referred for Septal Reduction Therapy: Outcomes Through 32 Weeks.

BACKGROUND: Septal reduction therapy (SRT) in patients with intractable symptoms from obstructive hypertrophic cardiomyopathy (oHCM) is associated with variable morbidity and mortality. The VALOR-HCM trial (A Study to Evaluate Mavacamten in Adults with Symptomatic Obstructive Hypertrophic Cardiomyopathy Who Are Eligible for Septal Reduction Therapy) examined the effect of mavacamten on the need for SRT through week 32 in oHCM. METHODS: A double-blind randomized placebo-controlled multicenter trial at 19 US sites included patients with oHCM on maximal tolerated medical therapy referred for SRT with left ventricular outflow tract gradient ≥50 mm Hg at rest or provocation (enrollment, July 2020-October 2021). The group initially randomized to mavacamten continued the drug for 32 weeks, and the placebo group crossed over to dose-blinded mavacamten from week 16 to week 32. Dose titrations were based on investigator-blinded echocardiographic assessment of left ventricular outflow tract gradient and left ventricular ejection fraction. The principal end point was the proportion of patients proceeding with SRT or remaining guideline eligible at 32 weeks in both treatment groups. RESULTS: From the 112 randomized patients with oHCM, 108 (mean age, 60.3 years; 50% men; 94% in New York Heart Association class III/IV) qualified for week 32 evaluation (56 in the original mavacamten group and 52 in the placebo cross-over group). After 32 weeks, 6 of 56 patients (10.7%) in the original mavacamten group and 7 of 52 patients (13.5%) in the placebo cross-over group met SRT guideline criteria or elected to undergo SRT. After 32 weeks, a sustained reduction in resting left ventricular outflow tract gradient (-33.0 mm Hg [95% CI, -41.1 to -24.9]) and Valsalva left ventricular outflow tract gradient (-43.0 mm Hg [95% CI, -52.1 to -33.9]) was observed in the original mavacamten group. A similar reduction in resting (-33.7 mm Hg [95% CI, -42.2 to -25.2]) and Valsalva (-52.9 mm Hg [95% CI, -63.2 to -42.6]) gradients was quantified in the cross-over group after 16 weeks of mavacamten. After 32 weeks, improvement by ≥1 New York Heart Association class was observed in 48 of 53 patients (90.6%) in the original mavacamten group and 35 of 50 patients (70%) after 16 weeks in the cross-over group. CONCLUSIONS: In severely symptomatic patients with oHCM, 32 weeks of mavacamten treatment showed sustained reduction in the proportion proceeding to SRT or remaining guideline eligible, with similar effects observed in patients who crossed over from placebo after 16 weeks. REGISTRATION: URL: https://www. CLINICALTRIALS: gov; Unique identifier: NCT04349072.

Mavacamten for treatment of symptomatic obstructive hypertrophic cardiomyopathy (EXPLORER-HCM): health status analysis of a randomised, double-blind, placebo-controlled, phase 3 trial.

BACKGROUND: Improving symptoms is a primary treatment goal in patients with obstructive hypertrophic cardiomyopathy. Currently available pharmacological options for hypertrophic cardiomyopathy are not disease-specific and are often inadequate or poorly tolerated. We aimed to assess the effect of mavacamten, a first-in-class cardiac myosin inhibitor, on patients' health status-ie, symptoms, physical and social function, and quality of life. METHODS: We did a health status analysis of EXPLORER-HCM, a phase 3, double-blind, randomised, placebo-controlled trial. The study took place at 68 clinical cardiovascular centres in 13 countries. Adult patients (≥18 years) with symptomatic obstructive hypertrophic cardiomyopathy (gradient ≥50 mm Hg and New York Heart Association class II-III) were randomly assigned (1:1) to mavacamten or placebo for 30 weeks, followed by an 8-week washout period. Both patients and staff were masked to study treatment. The primary outcome for this secondary analysis was the Kansas City Cardiomyopathy Questionnaire (KCCQ), a well validated disease-specific measure of patients' health status. It was administered at baseline and weeks 6, 12, 18, 30 (end of treatment), and 38 (end of study). Changes from baseline to week 30 in KCCQ overall summary (OS) score and all subscales were analysed using mixed model repeated measures. This study is registered with ClinicalTrials.gov, NCT03470545. FINDINGS: Between May 30, 2018, and July 12, 2019, 429 adults were assessed for eligibility, of whom 251 (59%) were enrolled and randomly assigned. Of 123 patients randomly assigned to mavacamten, 92 (75%) completed the KCCQ at baseline and week 30 and of the 128 patients randomly assigned to placebo 88 (69%) completed the KCCQ at baseline and week 30. At 30 weeks, the change in KCCQ-OS score was greater with mavacamten than placebo (mean score 14·9 [SD 15·8] vs 5·4 [13·7]; difference +9·1 [95% CI 5·5-12·8]; p<0·0001), with similar benefits across all KCCQ subscales. The proportion of patients with a very large change (KCCQ-OS ≥20 points) was 36% (33 of 92) in the mavacamten group versus 15% (13 of 88) in the placebo group, with an estimated absolute difference of 21% (95% CI 8·8-33·4) and number needed to treat of five (95% CI 3-11). These gains returned to baseline after treatment was stopped. INTERPRETATION: Mavacamten markedly improved the health status of patients with symptomatic obstructive hypertrophic cardiomyopathy compared with placebo, with a low number needed to treat for marked improvement. Given that the primary goals of treatment are to improve symptoms, physical and social function, and quality of life, mavacamten represents a new potential strategy for achieving these goals. FUNDING: MyoKardia, a Bristol Myers Squibb company.

Mavacamten for treatment of symptomatic obstructive hypertrophic cardiomyopathy (EXPLORER-HCM): a randomised, double-blind, placebo-controlled, phase 3 trial.

BACKGROUND: Cardiac muscle hypercontractility is a key pathophysiological abnormality in hypertrophic cardiomyopathy, and a major determinant of dynamic left ventricular outflow tract (LVOT) obstruction. Available pharmacological options for hypertrophic cardiomyopathy are inadequate or poorly tolerated and are not disease-specific. We aimed to assess the efficacy and safety of mavacamten, a first-in-class cardiac myosin inhibitor, in symptomatic obstructive hypertrophic cardiomyopathy. METHODS: In this phase 3, randomised, double-blind, placebo-controlled trial (EXPLORER-HCM) in 68 clinical cardiovascular centres in 13 countries, patients with hypertrophic cardiomyopathy with an LVOT gradient of 50 mm Hg or greater and New York Heart Association (NYHA) class II-III symptoms were assigned (1:1) to receive mavacamten (starting at 5 mg) or placebo for 30 weeks. Visits for assessment of patient status occurred every 2-4 weeks. Serial evaluations included echocardiogram, electrocardiogram, and blood collection for laboratory tests and mavacamten plasma concentration. The primary endpoint was a 1·5 mL/kg per min or greater increase in peak oxygen consumption (pVO2) and at least one NYHA class reduction or a 3·0 mL/kg per min or greater pVO2 increase without NYHA class worsening. Secondary endpoints assessed changes in post-exercise LVOT gradient, pVO2, NYHA class, Kansas City Cardiomyopathy Questionnaire-Clinical Summary Score (KCCQ-CSS), and Hypertrophic Cardiomyopathy Symptom Questionnaire Shortness-of-Breath subscore (HCMSQ-SoB). This study is registered with ClinicalTrials.gov, NCT03470545. FINDINGS: Between May 30, 2018, and July 12, 2019, 429 adults were assessed for eligibility, of whom 251 (59%) were enrolled and randomly assigned to mavacamten (n=123 [49%]) or placebo (n=128 [51%]). 45 (37%) of 123 patients on mavacamten versus 22 (17%) of 128 on placebo met the primary endpoint (difference +19·4%, 95% CI 8·7 to 30·1; p=0·0005). Patients on mavacamten had greater reductions than those on placebo in post-exercise LVOT gradient (-36 mm Hg, 95% CI -43·2 to -28·1; p<0·0001), greater increase in pVO2 (+1·4 mL/kg per min, 0·6 to 2·1; p=0·0006), and improved symptom scores (KCCQ-CSS +9·1, 5·5 to 12·7; HCMSQ-SoB -1·8, -2·4 to -1·2; p<0·0001). 34% more patients in the mavacamten group improved by at least one NYHA class (80 of 123 patients in the mavacamten group vs 40 of 128 patients in the placebo group; 95% CI 22·2 to 45·4; p<0·0001). Safety and tolerability were similar to placebo. Treatment-emergent adverse events were generally mild. One patient died by sudden death in the placebo group. INTERPRETATION: Treatment with mavacamten improved exercise capacity, LVOT obstruction, NYHA functional class, and health status in patients with obstructive hypertrophic cardiomyopathy. The results of this pivotal trial highlight the benefits of disease-specific treatment for this condition. FUNDING: MyoKardia.

Study design and rationale of VALOR-HCM: evaluation of mavacamten in adults with symptomatic obstructive hypertrophic cardiomyopathy who are eligible for septal reduction therapy.

BACKGROUND: Hypertrophic cardiomyopathy (HCM) is a primary myocardial disorder which frequently leads to symptoms such as dyspnea and exercise intolerance, often due to severe dynamic left ventricular outflow tract obstruction (LVOTO). Current guideline-recommended pharmacotherapies have variable therapeutic responses to relieve LVOTO. In recent phases 2 and 3, clinical trials for symptomatic obstructive HCM (oHCM), mavacamten, a small molecule inhibitor of ß-cardiac myosin has been shown to improve symptoms, exercise capacity, health status, reduce LVOTO, along with having a beneficial impact on cardiac structure and function. METHODS: VALOR-HCM is designed as a multicenter (approximately 20 centers in United States) phase 3, double-blind, placebo-controlled, randomized study. The study population consists of approximately 100 patients (≥18 years old) with symptomatic oHCM who meet 2011 American College of Cardiology/American Heart Association and/or 2014 European Society of Cardiology HCM-guideline criteria and are eligible and willing to undergo septal reduction therapy (SRT). The study duration will be up to 138 weeks, including an initial 2-week screening period, followed by16 weeks of placebo-controlled treatment, 16 weeks of active blinded treatment, 96 weeks of long-term extension, and an 8-week posttreatment follow-up visit. The primary endpoint will be a composite of the decision to proceed with SRT prior to or at Week 16 or remain guideline eligible for SRT at Week 16. Secondary efficacy endpoints will include change (from baseline to Week 16 in the mavacamten group vs placebo) in postexercise LVOT gradient, New York Heart Association class, Kansas City Cardiomyopathy Questionnaire clinical summary score, NT-proBNP, and cardiac troponin. Exploratory endpoints aim to characterize the effect of mavacamten on multiple aspects of oHCM pathophysiology. CONCLUSIONS: In severely symptomatic drug-refractory oHCM patients meeting guideline criteria of eligibility for SRT, VALOR-HCM will primarily study if a 16-week course of mavacamten reduces or obviates the need for SRT using clinically driven endpoints.

Mavacamten Treatment for Obstructive Hypertrophic Cardiomyopathy: A Clinical Trial.

Background: Mavacamten, an orally administered, small-molecule modulator of cardiac myosin, targets underlying biomechanical abnormalities in obstructive hypertrophic cardiomyopathy (oHCM). Objective: To characterize the effect of mavacamten on left ventricular outflow tract (LVOT) gradient. Design: Open-label, nonrandomized, phase 2 trial. (ClinicalTrials.gov: NCT02842242). Setting: 5 academic centers. Participants: 21 symptomatic patients with oHCM. Intervention: Patients in cohort A received mavacamten, 10 to 20 mg/d, without background medications. Those in cohort B received mavacamten, 2 to 5 mg/d, with ß-blockers allowed. Measurements: The primary end point was change in postexercise LVOT gradient at 12 weeks. Secondary end points included changes in peak oxygen consumption (pVO2), resting and Valsalva LVOT gradients, left ventricular ejection fraction (LVEF), and numerical rating scale dyspnea score. Results: In cohort A, mavacamten reduced mean postexercise LVOT gradient from 103 mm Hg (SD, 50) at baseline to 19 mm Hg (SD, 13) at 12 weeks (mean change, -89.5 mm Hg [95% CI, -138.3 to -40.7 mm Hg]; P = 0.008). Resting LVEF was also reduced (mean change, -15% [CI, -23% to -6%]). Peak VO2 increased by a mean of 3.5 mL/kg/min (CI, 1.2 to 5.9 mL/kg/min). In cohort B, the mean postexercise LVOT gradient decreased from 86 mm Hg (SD, 43) to 64 mm Hg (SD, 26) (mean change, -25.0 mm Hg [CI, -47.1 to -3.0 mm Hg]; P = 0.020), and mean change in resting LVEF was -6% (CI, -10% to -1%). Peak VO2 increased by a mean of 1.7 mL/kg/min (SD, 2.3) (CI, 0.03 to 3.3 mL/kg/min). Dyspnea scores improved in both cohorts. Mavacamten was well tolerated, with mostly mild (80%), moderate (19%), and unrelated (79%) adverse events. The most common adverse events definitely or possibly related to mavacamten were decreased LVEF at higher plasma concentrations and atrial fibrillation. Limitation: Small size; open-label design. Conclusion: Mavacamten can reduce LVOT obstruction and improve exercise capacity and symptoms in patients with oHCM. Primary Funding Source: MyoKardia.

DNA sequencing versus standard prenatal aneuploidy screening.

BACKGROUND: In high-risk pregnant women, noninvasive prenatal testing with the use of massively parallel sequencing of maternal plasma cell-free DNA (cfDNA testing) accurately detects fetal autosomal aneuploidy. Its performance in low-risk women is unclear. METHODS: At 21 centers in the United States, we collected blood samples from women with singleton pregnancies who were undergoing standard aneuploidy screening (serum biochemical assays with or without nuchal translucency measurement). We performed massively parallel sequencing in a blinded fashion to determine the chromosome dosage for each sample. The primary end point was a comparison of the false positive rates of detection of fetal trisomies 21 and 18 with the use of standard screening and cfDNA testing. Birth outcomes or karyotypes were the reference standard. RESULTS: The primary series included 1914 women (mean age, 29.6 years) with an eligible sample, a singleton fetus without aneuploidy, results from cfDNA testing, and a risk classification based on standard screening. For trisomies 21 and 18, the false positive rates with cfDNA testing were significantly lower than those with standard screening (0.3% vs. 3.6% for trisomy 21, P<0.001; and 0.2% vs. 0.6% for trisomy 18, P=0.03). The use of cfDNA testing detected all cases of aneuploidy (5 for trisomy 21, 2 for trisomy 18, and 1 for trisomy 13; negative predictive value, 100% [95% confidence interval, 99.8 to 100]). The positive predictive values for cfDNA testing versus standard screening were 45.5% versus 4.2% for trisomy 21 and 40.0% versus 8.3% for trisomy 18. CONCLUSIONS: In a general obstetrical population, prenatal testing with the use of cfDNA had significantly lower false positive rates and higher positive predictive values for detection of trisomies 21 and 18 than standard screening. (Funded by Illumina; ClinicalTrials.gov number, NCT01663350.).

Noninvasive detection of fetal subchromosome abnormalities via deep sequencing of maternal plasma.

The purpose of this study was to determine the deep sequencing and analytic conditions needed to detect fetal subchromosome abnormalities across the genome from a maternal blood sample. Cell-free (cf) DNA was isolated from the plasma of 11 pregnant women carrying fetuses with subchromosomal duplications and deletions, translocations, mosaicism, and trisomy 20 diagnosed by metaphase karyotype. Massively parallel sequencing (MPS) was performed with 25-mer tags at approximately 10(9) tags per sample and mapped to reference human genome assembly hg19. Tags were counted and normalized to fixed genome bin sizes of 1 Mb or 100 kb to detect statistically distinct copy-number changes compared to the reference. All seven cases of microdeletions, duplications, translocations, and the trisomy 20 were detected blindly by MPS, including a microdeletion as small as 300 kb. In two of these cases in which the metaphase karyotype showed additional material of unknown origin, MPS identified both the translocation breakpoint and the chromosomal origin of the additional material. In the four mosaic cases, the subchromosomal abnormality was not demonstrated by MPS. This work shows that in nonmosaic cases, it is possible to obtain a fetal molecular karyotype by MPS of maternal plasma cfDNA that is equivalent to a chromosome microarray and in some cases is better than a metaphase karyotype. This approach combines the advantage of enhanced fetal genomic resolution with the improved safety of a noninvasive maternal blood test.

Women's views and the impact of noninvasive prenatal testing on procedures in a managed care setting.

OBJECTIVE: To prospectively determine the impact of noninvasive prenatal testing (NIPT) on invasive procedure utilization in a managed care setting and to elucidate women's views. METHODS: Pregnant women at 10- 20 weeks' gestation with high-risk indications for fetal aneuploidy in the Kaiser Permanente Southern California organization were eligible. Enrolled patients received routine prenatal counseling, completed a questionnaire and were offered the option of NIPT by a genetic counselor. Downstream data through 28 weeks' gestation were collected from the electronic medical record (EMR). The EMR was also used to identify a matched historical cohort from 1 year prior to NIPT availability. Rates of invasive prenatal procedures were compared using McNemar's test. RESULTS: Two hundred women completed the questionnaire and underwent NIPT. Twenty-two subjects (11%) in the prospective cohort underwent an invasive prenatal procedure compared with 58 (29%) in the historical cohort (p<0.0001). Safety and accuracy were the most important factors in considering NIPT. At the time of survey, only 12% indicated being very comfortable with the possibility of undergoing amniocentesis. CONCLUSION: This prospective study demonstrates a 62% reduction in invasive prenatal procedures after NIPT testing and finds safety, accuracy, and personal beliefs key to women's decision-making.

Noninvasive Prenatal Testing and Incidental Detection of Occult Maternal Malignancies.

IMPORTANCE: Understanding the relationship between aneuploidy detection on noninvasive prenatal testing (NIPT) and occult maternal malignancies may explain results that are discordant with the fetal karyotype and improve maternal clinical care. OBJECTIVE: To evaluate massively parallel sequencing data for patterns of copy-number variations that might prospectively identify occult maternal malignancies. DESIGN, SETTING, AND PARTICIPANTS: Case series identified from 125,426 samples submitted between February 15, 2012, and September 30, 2014, from asymptomatic pregnant women who underwent plasma cell-free DNA sequencing for clinical prenatal aneuploidy screening. Analyses were conducted in a clinical laboratory that performs DNA sequencing. Among the clinical samples, abnormal results were detected in 3757 (3%); these were reported to the ordering physician with recommendations for further evaluation. EXPOSURES: NIPT for fetal aneuploidy screening (chromosomes 13, 18, 21, X, and Y). MAIN OUTCOMES AND MEASURES: Detailed genome-wide bioinformatics analysis was performed on available sequencing data from 8 of 10 women with known cancers. Genome-wide copy-number changes in the original NIPT samples and in subsequent serial samples from individual patients when available are reported. Copy-number changes detected in NIPT sequencing data in the known cancer cases were compared with the types of aneuploidies detected in the overall cohort. RESULTS: From a cohort of 125,426 NIPT results, 3757 (3%) were positive for 1 or more aneuploidies involving chromosomes 13, 18, 21, X, or Y. From this set of 3757 samples, 10 cases of maternal cancer were identified. Detailed clinical and sequencing data were obtained in 8. Maternal cancers most frequently occurred with the rare NIPT finding of more than 1 aneuploidy detected (7 known cancers among 39 cases of multiple aneuploidies by NIPT, 18% [95% CI, 7.5%-33.5%]). All 8 cases that underwent further bioinformatics analysis showed unique patterns of nonspecific copy-number gains and losses across multiple chromosomes. In 1 case, blood was sampled after completion of treatment for colorectal cancer and the abnormal pattern was no longer evident. CONCLUSIONS AND RELEVANCE: In this preliminary study, a small number of cases of occult malignancy were subsequently diagnosed among pregnant women whose noninvasive prenatal testing results showed discordance with the fetal karyotype. The clinical importance of these findings will require further research.

Circulating fetal cell-free DNA fractions differ in autosomal aneuploidies and monosomy X.

BACKGROUND: Noninvasive prenatal testing based on massively parallel sequencing (MPS) of cell-free DNA in maternal plasma has become rapidly integrated into clinical practice for detecting fetal chromosomal aneuploidy. We directly determined the fetal fraction (FF) from results obtained with MPS tag counting and examined the relationships of FF to such biological parameters as fetal karyotype and maternal demographics. METHODS: FF was determined from samples previously collected for the MELISSA (Maternal Blood Is Source to Accurately Diagnose Fetal Aneuploidy) study. Samples were resequenced, analyzed blindly, and aligned to the human genome (assembly hg19). FF was calculated in pregnancies with male or aneuploid fetuses by means of an equation that incorporated the ratio of the tags in these samples to those of a euploid training set. RESULTS: The mean (SD) FF from euploid male pregnancies was 0.126 (0.052) (n = 160). Weak but statistically significant correlations were found between FF and the maternal body mass index (r(2) = 0.18; P = 2.3 × 10(-8)) and between FF and gestational age (r(2) = 0.02; P = 0.047). No relationship with maternal ethnicity or age was observed. Mean FF values for trisomies 21 (n = 90), 18 (n = 38), and 13 (n = 16) and for monosomy X (n = 20) were 0.135 (0.051), 0.089 (0.039), 0.090 (0.062), and 0.106 (0.045), respectively. CONCLUSIONS: MPS tag-count data can be used to determine FF directly and accurately. Compared with male euploid fetuses, the FF is higher in maternal plasma when the fetus has trisomy 21 and is lower when the fetus has trisomy 18, 13, or monosomy X. The different biologies of these aneuploidies have practical implications for the determination of cutoff values, which in turn will affect the diagnostic sensitivity and specificity of the test.

Impact of noninvasive prenatal testing in regionally dispersed medical centers in the United States.

OBJECTIVE: Noninvasive prenatal testing using cell-free DNA is a new alternative to screen for common fetal aneuploidies. It is not known what impact regional location may play on noninvasive prenatal testing implementation and downstream invasive prenatal procedure use in the United States. STUDY DESIGN: Six different regionally based centers collected data on noninvasive prenatal testing indication and results between February and November 2012, as well as their invasive prenatal procedure rates before and after offering noninvasive prenatal testing. Statistical analyses were performed using the 2-proportion Z-test. RESULTS: Of 1477 patients who underwent noninvasive prenatal testing; 693 (47%) were from centers in the West; 522 (35.3%) from centers in the East; and 262 (17.7%) from 1 center in the Midwest. Statistically significant differences were observed between West Coast and nonWest Coast sites for gestational age (14.1 weeks; P ≤ .0001). Advanced maternal age (AMA-only) was the most frequent indication in 5 of 6 sites (range, 21.8-62.9%) A total of 98 invasive prenatal procedures performed on 94 (6.4%) patients of which 64 (65.3%) were performed at centers in the West. More invasive procedures were performed following negative noninvasive prenatal testing results (n = 61) than abnormal noninvasive prenatal testing results (n = 30). The overall rate of patients undergoing invasive procedure after an abnormal noninvasive prenatal testing result was 32.6% (30 of 92). All 6 centers reported a decrease in invasive procedure volume after noninvasive prenatal testing introduction. CONCLUSION: This study demonstrates differences in clinical implementation of noninvasive prenatal testing across regionally dispersed centers in the United States, suggesting patient demographics and views toward prenatal testing influence use as well as downstream management.

Mavacamten for Obstructive Hypertrophic Cardiomyopathy: Rationale for Clinically Guided Dose Titration to Optimize Individual Response.

Mavacamten is the first and only cardiac myosin inhibitor approved in 5 continents for the treatment of adults with symptomatic New York Heart Association class II and III obstructive hypertrophic cardiomyopathy. An evidence-based rationale was used to develop individualized mavacamten dosing, guided by commonly used clinical parameters. Echocardiography is recommended as part of routine clinical assessment of patients with hypertrophic cardiomyopathy, and left ventricular (LV) outflow tract gradient and LV ejection fraction are parameters that can be readily assessed and monitored by echocardiography. Therefore, an echocardiography-based, clinically guided dose-titration strategy was developed to optimize patient benefit from mavacamten for the treatment of symptomatic obstructive hypertrophic cardiomyopathy while minimizing the risk of LV ejection fraction reduction. Results from clinical trials paired with extensive modeling and simulation analyses support a dose-titration and monitoring strategy based on serial echocardiographic measures of Valsalva LV outflow tract gradient and LV ejection fraction. This dosing approach allows for the identification of the lowest individualized mavacamten dose and exposure required to provide improvements in LV outflow tract obstruction, functional capacity, and symptoms. Mavacamten is primarily metabolized by CYP2C19 (cytochrome P450 2C19), and CYP2C19 metabolizer phenotype has an effect on mavacamten exposure. Therefore, this approach has also been demonstrated to provide a favorable safety profile irrespective of patients' CYP2C19 metabolizer status. The dose-titration strategy includes additional considerations for the potential onset of systolic dysfunction in the context of intercurrent illness, and for the potential of drug-drug interactions with inhibitors and substrates of cytochrome P450 enzymes. This posology is reflected in the mavacamten US prescribing information.

Long-Term Safety and Efficacy of Mavacamten in Symptomatic Obstructive Hypertrophic Cardiomyopathy: Interim Results of the PIONEER-OLE Study.

BACKGROUND: The phase 2 PIONEER-HCM (Phase 2 Open-label Pilot Study Evaluating Mavacamten in Subjects With Symptomatic Hypertrophic Cardiomyopathy and Left Ventricular Outflow Tract Obstruction) study showed that mavacamten improved left ventricular outflow tract gradients, exercise capacity, and symptoms in patients with obstructive hypertrophic cardiomyopathy (HCM), but the results of longer-term treatment are less well described. We report interim results from the PIONEER-OLE (PIONEER Open-Label Extension) study, the longest-term study of mavacamten in patients with symptomatic obstructive HCM. METHODS AND RESULTS: Patients who previously completed PIONEER-HCM (n=20) were eligible to enroll in PIONEER-OLE. Patients received oral mavacamten, 5 mg once daily (starting dose), with individualized dose titration at week 6. Evaluations included serial monitoring of safety, echocardiography, Kansas City Cardiomyopathy Questionnaire-Overall Summary Score, and serum NT-proBNP (N-terminal pro-B-type natriuretic peptide) levels. Thirteen patients enrolled and received mavacamten (median study duration at data cutoff, 201 weeks). Most patients (92.3%) received ß-blockers concomitantly. Treatment-emergent adverse events were predominantly mild/moderate. One patient had an isolated reduction in left ventricular ejection fraction to 47%, which recovered and remained normal with continued treatment at a reduced dose. At week 180, mavacamten was associated with New York Heart Association class improvements from baseline (class II to I, n=9; class III to II, n=1; and unchanged, n=2), sustained reductions in left ventricular outflow tract gradients (mean [SD] change from baseline: resting, -50 [55] mm Hg; Valsalva, -70 [41] mm Hg), and serum NT-proBNP levels (median [interquartile range] change from baseline: -498 [-2184 to -76] ng/L), and improved Kansas City Cardiomyopathy Questionnaire-Overall Summary Score (mean [SD] change from baseline: +17 [16]). CONCLUSIONS: This long-term analysis supports the continued safety and effectiveness of mavacamten for >3 years in obstructive HCM. REGISTRATION: URL: https://www.clinicaltrials.gov; Unique identifier: NCT03496168.

Recommendation of mavacamten posology by model-based analyses in adults with obstructive hypertrophic cardiomyopathy.

Mavacamten is the first cardiac myosin inhibitor approved by the US Food and Drug Administration for the treatment of adults with symptomatic obstructive hypertrophic cardiomyopathy (HCM). The phase III EXPLORER-HCM (NCT03470545) study used a dose-titration scheme based on mavacamten exposure and echocardiographic assessment of Valsalva left ventricular outflow tract gradient (VLVOTg) and left ventricular ejection fraction (LVEF). Using population pharmacokinetic/exposure-response modeling and simulations of virtual patients, this in silico study evaluated alternative dose-titration regimens for mavacamten, including regimens that were guided by echocardiographic measures only. Mavacamten exposure-response models for VLVOTg (efficacy) and LVEF (safety) were developed using patient data from five clinical studies and characterized using nonlinear mixed-effects models. Simulations of five echocardiography-guided regimens were performed in virtual cohorts constructed based on either expected or equal population distributions of cytochrome P450 2C19 (CYP2C19) metabolizer phenotypes. Each regimen aimed to maximize the proportions of patients who achieved a VLVOTg below 30 mm Hg while maintaining LVEF above 50% over 40 weeks and 104 weeks, respectively. The exposure-response models successfully characterized mavacamten efficacy and safety parameters. Overall, the simulated regimen with the optimal benefit-risk profile across CYP2C19 phenotypes had steps for down-titration at weeks 4 and 8 (for VLVOTg <20 mm Hg), and up-titration at week 12 (for VLVOTg ≥30 mm Hg and LVEF ≥55%), and every 12 weeks thereafter. This simulation-optimized regimen is recommended in the mavacamten US prescribing information.

Characterization of mavacamten pharmacokinetics in patients with hypertrophic cardiomyopathy to inform dose titration.

Mavacamten is a selective, allosteric, reversible cardiac myosin inhibitor that has been developed for the treatment of adults with symptomatic obstructive hypertrophic cardiomyopathy (HCM). A population pharmacokinetic (PopPK) model was developed to characterize mavacamten pharmacokinetics (PK) and the variation in mavacamten exposure associated with intrinsic and extrinsic factors. Data from 12 clinical studies (phases 1, 2, and 3) were used. Evaluable participants were those who had at least one mavacamten concentration measurement with associated sampling time and dosing information. The base model included key covariates: body weight, cytochrome P450 isozyme 2C19 (CYP2C19) phenotype with respect to PK, and formulation. The final model was generated using stepwise covariate testing and refinement processes. Simulations were performed to evaluate PK: apparent clearance (CL/F); apparent central and peripheral volumes of distribution; and steady-state average, trough, and maximum concentrations. Overall, 9244 measurable PK observations from 497 participants were included. A two-compartment model structure was selected. After stepwise covariate model building and refinement, additional covariates included were: specified mavacamten dose, omeprazole or esomeprazole administration, health/disease status, estimated glomerular filtration rate, fed status, and sex. The final PopPK model accurately characterized mavacamten concentrations. At any given dose, CYP2C19 phenotype was the most influential covariate on exposure parameters (e.g., median CL/F was reduced by 72% in CYP2C19:poor metabolizers compared with the reference participant [CYP2C19:normal metabolizer]). CL/F was also approximately 16% higher in women than in men but lower in participants receiving concomitant omeprazole or esomeprazole (by 33% and 42%, respectively) than in participants not receiving such concomitant therapy.

Mavacamten-Associated Temporal Changes in Left Atrial Function in Obstructive HCM: Insights From the VALOR-HCM Trial.

BACKGROUND: In severely symptomatic patients with obstructive hypertrophic cardiomyopathy (HCM), the VALOR-HCM (A Study to Evaluate Mavacamten in Adults With Symptomatic Obstructive Hypertrophic Cardiomyopathy Who Are Eligible for Septal Reduction Therapy) trial showed that mavacamten reduced the eligibility for septal reduction therapy with sustained improvement in left ventricular outflow tract gradients. Mavacamten also resulted in favorable cardiac remodeling, including improvement in biomarkers (eg, N-terminal pro-B-type natriuretic peptide and troponin T). However, the impact of mavacamten on left atrial (LA) function is unknown. OBJECTIVES: The aim of this study was to assess serial changes in LA strain measures in patients enrolled in the VALOR-HCM trial. METHODS: VALOR-HCM included 112 symptomatic patients with obstructive HCM (mean age 60 years; 51% male). Patients assigned to receive mavacamten at baseline (n = 56) continued therapy for 56 weeks and those assigned to placebo transitioned to mavacamten (n = 52) from week 16 to week 56. Echocardiographic LA strain (reservoir, conduit, and contraction) was measured by using a vendor-neutral postprocessing software. RESULTS: At baseline, the mean LA volume index (LAVI) and LA strain values (conduit, contraction, and reservoir) were 41.3 ± 16.5 mL/m2, -11.8% ± 6.5%, -8.7% ± 5.0%, and 20.5% ± 8.7%, respectively (all worse than reported normal). LAVI significantly improved by -5.6 ± 9.7 mL/m2 from baseline to week 56 (P < 0.001). There was a significant (P < 0.05) improvement in absolute LA strain values from baseline to week 56 (conduit [-1.7% ± 6%], contraction [-1.2% ± 4.5%], and reservoir [2.8% ± 7.7%]). Patients originally receiving placebo had no differences in LA measurements up to week 16. There was no significant improvement in LA strain values (conduit [-0.9% ± 3.8%], contraction [-0.4% ± 3.4%], and reservoir [1.4% ± 6.1%]; all; P = NS) from baseline to week 56 in patients with history of atrial fibrillation. CONCLUSIONS: In VALOR-HCM, mavacamten resulted in an improvement in LAVI and LA strain at week 56, suggesting sustained favorable LA remodeling and improved function, except in the atrial fibrillation subgroup. Whether the advantageous LA remodeling associated with long-term treatment with mavacamten results in a favorable impact on the observed high burden of atrial tachyarrhythmias in HCM remains to be proven. (A Study to Evaluate Mavacamten in Adults With Symptomatic Obstructive Hypertrophic Cardiomyopathy Who Are Eligible for Septal Reduction Therapy [VALOR-HCM]; NCT04349072).

Mavacamten Treatment for Symptomatic Obstructive Hypertrophic Cardiomyopathy: Interim Results From the MAVA-LTE Study, EXPLORER-LTE Cohort.

BACKGROUND: Data assessing the long-term safety and efficacy of mavacamten treatment for symptomatic obstructive hypertrophic cardiomyopathy are needed. OBJECTIVES: The authors sought to evaluate interim results from the EXPLORER-Long Term Extension (LTE) cohort of MAVA-LTE (A Long-Term Safety Extension Study of Mavacamten in Adults Who Have Completed EXPLORER-HCM; NCT03723655). METHODS: After mavacamten or placebo withdrawal at the end of the parent EXPLORER-HCM (Clinical Study to Evaluate Mavacamten [MYK-461] in Adults With Symptomatic Obstructive Hypertrophic Cardiomyopathy; NCT03470545), patients could enroll in MAVA-LTE. Patients received mavacamten 5 mg once daily; adjustments were made based on site-read echocardiograms. RESULTS: Between April 9, 2019, and March 5, 2021, 231 of 244 eligible patients (94.7%) enrolled in MAVA-LTE (mean age: 60 years; 39% female). At data cutoff (August 31, 2021) 217 (93.9%) remained on treatment (median time in study: 62.3 weeks; range: 0.3-123.9 weeks). At 48 weeks, patients showed improvements in left ventricular outflow tract (LVOT) gradients (mean change ± SD from baseline: resting: -35.6 ± 32.6 mm Hg; Valsalva: -45.3 ± 35.9 mm Hg), N-terminal pro-B-type natriuretic peptide (NT-proBNP) levels (median: -480 ng/L; Q1-Q3: -1,104 to -179 ng/L), and NYHA functional class (67.5% improved by ≥1 class). LVOT gradients and NT-proBNP reductions were sustained through 84 weeks in patients who reached this timepoint. Over 315 patient-years of exposure, 8 patients experienced an adverse event of cardiac failure, and 21 patients had an adverse event of atrial fibrillation, including 11 with no prior history of atrial fibrillation. Twelve patients (5.2%) developed transient reductions in site-read echocardiogram left ventricular ejection fraction of <50%, resulting in temporary treatment interruption; all recovered. Ten patients discontinued treatment due to treatment-emergent adverse events. CONCLUSIONS: Mavacamten treatment showed clinically important and durable improvements in LVOT gradients, NT-proBNP levels, and NYHA functional class, consistent with EXPLORER-HCM. Mavacamten treatment was well tolerated over a median 62-week follow-up.