APOLLO-B, a study of patisiran in patients with transthyretin cardiac amyloidosis: primary long-term results from the open-label extension period

INTRODUCTION: The Phase 3 APOLLO-B study evaluates patisiran in patients (pts) with transthyretin (ATTR) cardiac amyloidosis over a 12-month (M) double-blind (DB) period, followed by an open-label extension (OLE) period when all pts receive patisiran (NCT03997383). Hypothesis: Patisiran provides long-term benefit in pts with ATTR cardiac amyloidosis. Aims: Describe safety and efficacy of patisiran during the APOLLO-B OLE (18M+). METHODS: Pts (18-85 yrs) with ATTR cardiac amyloidosis and heart failure history were randomized 1:1 to patisiran or placebo (pbo). Pts completing DB period were eligible to receive patisiran in the OLE for ≤36M. Results summarized based on DB treatment arm. Exploratory assessments include change from study baseline (CFB) in 6-minute walk test (6MWT), KCCQ-OS, NT-proBNP, and troponin I. RESULTS: In the DB period, 359 pts (pbo n=178; patisiran n=181) received study drug (median [range] age, 76.0 [41, 85] yrs; male, 89%; wtATTR, 80%; tafamidis at baseline, 25%); 334 (93%) entered the OLE. In patisiran arm, M12 and M18 results, respectively, were similar for each endpoint: 6MWT and KCCQ-OS (mean [SEM] CFB) −8.09 [5.73] vs −9.21 [6.04] meters (m) and 0.60 [1.36] vs 0.22 [1.48]; NT-proBNP and troponin I (geometric mean fold-CFB [95%CI]) 1.10 [1.03, 1.17] vs 1.17 [1.07, 1.27] and 1.11 [1.05, 1.18] vs 1.09 [1.01, 1.17]). In pbo arm, patisiran initiation in OLE was associated with a slower rate of worsening or relative stability across endpoints; CFB at M12 vs M18, respectively: 6MWT, −25.43 [5.61] vs −31.08 [5.45] m; KCCQ-OS, −3.41 [1.33] vs −4.02 [1.49]; NT-proBNP, 1.39 [1.28, 1.51] vs 1.53 [1.38, 1.71]; and troponin I, 1.29 [1.21, 1.38] vs 1.21 [1.13, 1.30]. Patisiran had an acceptable safety profile; no new concerns. OLE analyses are ongoing; updated data to be presented. CONCLUSIONS: The M18 results provide evidence that beneficial effects observed in DB period on functional capacity, health status, and quality of life were maintained by continued treatment with patisiran during the OLE. Pbo-treated pts initiating patisiran at M12 showed slowed worsening or stabilization in most endpoints at M18. Early treatment initiation is important: pbo-treated pts did not recover functional capacity or health lost prior to initiating OLE patisiran.

Patisiran Treatment in Patients with Transthyretin Cardiac Amyloidosis.

BACKGROUND: Transthyretin amyloidosis, also called ATTR amyloidosis, is associated with accumulation of ATTR amyloid deposits in the heart and commonly manifests as progressive cardiomyopathy. Patisiran, an RNA interference therapeutic agent, inhibits the production of hepatic transthyretin. METHODS: In this phase 3, double-blind, randomized trial, we assigned patients with hereditary, also known as variant, or wild-type ATTR cardiac amyloidosis, in a 1:1 ratio, to receive patisiran (0.3 mg per kilogram of body weight) or placebo once every 3 weeks for 12 months. A hierarchical procedure was used to test the primary and three secondary end points. The primary end point was the change from baseline in the distance covered on the 6-minute walk test at 12 months. The first secondary end point was the change from baseline to month 12 in the Kansas City Cardiomyopathy Questionnaire-Overall Summary (KCCQ-OS) score (with higher scores indicating better health status). The second secondary end point was a composite of death from any cause, cardiovascular events, and change from baseline in the 6-minute walk test distance over 12 months. The third secondary end point was a composite of death from any cause, hospitalizations for any cause, and urgent heart failure visits over 12 months. RESULTS: A total of 360 patients were randomly assigned to receive patisiran (181 patients) or placebo (179 patients). At month 12, the decline in the 6-minute walk distance was lower in the patisiran group than in the placebo group (Hodges-Lehmann estimate of median difference, 14.69 m; 95% confidence interval [CI], 0.69 to 28.69; P = 0.02); the KCCQ-OS score increased in the patisiran group and declined in the placebo group (least-squares mean difference, 3.7 points; 95% CI, 0.2 to 7.2; P = 0.04). Significant benefits were not observed for the second secondary end point. Infusion-related reactions, arthralgia, and muscle spasms occurred more often among patients in the patisiran group than among those in the placebo group. CONCLUSIONS: In this trial, administration of patisiran over a period of 12 months resulted in preserved functional capacity in patients with ATTR cardiac amyloidosis. (Funded by Alnylam Pharmaceuticals; APOLLO-B ClinicalTrials.gov number, NCT03997383.).

Arrhythmias as Presentation of Genetic Cardiomyopathy.

There is increasing evidence regarding the prevalence of genetic cardiomyopathies, for which arrhythmias may be the first presentation. Ventricular and atrial arrhythmias presenting in the absence of known myocardial disease are often labelled as idiopathic, or lone. While ventricular arrhythmias are well-recognized as presentation for arrhythmogenic cardiomyopathy in the right ventricle, the scope of arrhythmogenic cardiomyopathy has broadened to include those with dominant left ventricular involvement, usually with a phenotype of dilated cardiomyopathy. In addition, careful evaluation for genetic cardiomyopathy is also warranted for patients presenting with frequent premature ventricular contractions, conduction system disease, and early onset atrial fibrillation, in which most detected genes are in the cardiomyopathy panels. Sudden death can occur early in the course of these genetic cardiomyopathies, for which risk is not adequately tracked by left ventricular ejection fraction. Only a few of the cardiomyopathy genotypes implicated in early sudden death are recognized in current indications for implantable cardioverter defibrillators which otherwise rely upon a left ventricular ejection fraction ≤0.35 in dilated cardiomyopathy. The genetic diagnoses impact other aspects of clinical management such as exercise prescription and pharmacological therapy of arrhythmias, and new therapies are coming into clinical investigation for specific genetic cardiomyopathies. The expansion of available genetic information and implications raises new challenges for genetic counseling, particularly with the family member who has no evidence of a cardiomyopathy phenotype and may face a potentially negative impact of a genetic diagnosis. Discussions of risk for both probands and relatives need to be tailored to their numeric literacy during shared decision-making. For patients presenting with arrhythmias or cardiomyopathy, extension of genetic testing and its implications will enable cascade screening, intervention to change the trajectory for specific genotype-phenotype profiles, and enable further development and evaluation of emerging targeted therapies.

Outcomes in patients with cardiac amyloidosis and implantable cardioverter-defibrillator.

AIMS: Cardiac amyloidosis (CA) is associated with increased mortality due to arrhythmias, heart failure, and electromechanical dissociation. However, the role of an implantable cardioverter-defibrillator (ICD) remains unclear. We conducted case-control study to assess survival in CA patients with and without a primary prevention ICD and compared outcomes to an age, sex, and device implant year-matched non-CA group with primary prevention ICD. METHODS AND RESULTS: There were 91 subjects with CA [mean age= 71.2 ± 10.2, female 22.0%, 49 AL with Mayo Stage 2.9 ± 1.0, 41 transthyretin amyloidosis (ATTR), 1 other] followed by Vanderbilt Amyloidosis centre. Patients with ICD (n = 23) were compared with those without (n = 68) and a non-amyloid group with ICD (n = 46). All subjects with ICD had implantation for primary prevention. Mean left ventricular ejection fraction was 36.2% ± 14.4% in CA with ICD, 41.0% ± 10.6% in CA without ICD, and 33.5% ± 14.4% in non-CA patients. Over 3.5 ± 3.1 years, 6 (26.1%) CA, and 12 (26.1%) non-CA subjects received ICD therapies (P = 0.71). Patients with CA had a significantly higher mortality (43.9% vs. 17.4%, P = 0.002) compared with the non-CA group. Mean time from device implantation to death was 21.8 months in AL and 22.8 months in ATTR patients. There was no significant difference in mortality between CA patients who did and did not receive an ICD (39.0% vs. 46.0%, P = 0.59). CONCLUSIONS: Despite comparable event rates patients with CA had a significantly higher mortality and ICDs were not associated with longer survival. With the emergence of effective therapy for AL amyloidosis, further study of ICD is needed in this group.

Endothelial IKK beta signaling is required for monocyte adhesion under laminar flow conditions.

Endothelial activation induces expression of pro-inflammatory molecules that are thought to play an important role in atherogenesis through enhanced vascular monocyte recruitment. Many pro-inflammatory endothelial signals are transcriptionally regulated by members of the NF- kappa B family. The serine-threonine kinase, IKK beta, can mediate NF- kappa B activation although several alternative pathways exist. To test whether IKK beta is necessary for cytokine activation of human vascular endothelium and endothelial recruitment of human monocytes under laminar flow, we constructed a recombinant adenoviral vector carrying a dominant negative mutant of IKK beta (Ad.dnIKK beta) to transduce human umbilical vein endothelial cells (HUVEC) in vitro. We found that dnIKK beta expression effectively blocked NF-kappa B activation as assessed by nuclear translocation of NF-kappa B, I kappa B degradation, and NF-kappa B dependent reporter expression, without affecting activation of the other relevant signaling pathways, SAPK/JNK and p38. Furthermore, overexpression of dnIKK beta in TNF-alpha-stimulated HUVEC blocked induction of the surface adhesion molecules E-selectin, ICAM-1, and VCAM-1. Under simulated physiologic flow conditions, both firm adhesion and rolling of human peripheral monocytes on dnIKK beta-transduced endothelial monolayers were markedly inhibited. We conclude that IKK beta is necessary for the cytokine-induced inflammatory phenotype of human endothelium and endothelial recruitment of human monocytes under flow.