Will the FAbry STabilization indEX make its way to everyday clinical practice?

An expert consensus on practical clinical recommendations and guidance for patients with classic Fabry disease

Fabry disease is an X-linked inherited lysosomal disorder that causes accumulation of glycosphingolipids in body fluids and tissues, leading to progressive organ damage and reduced life expectancy. It can affect both males and females and can be classified into classic or later-onset phenotypes. In classic Fabry disease, α-galactosidase A (α-Gal A) activity is absent or severely reduced and disease manifestations have an early onset that can affect multiple organs. In contrast, in later-onset Fabry disease, patients have residual α-Gal A activity and clinical features are primarily confined to the heart. Individualized therapeutic goals in Fabry disease are required due to varying phenotypes and patient characteristics, and the wide spectrum of disease severity. An international group of expert physicians convened to discuss and develop practical clinical recommendations for disease- and organ-specific therapeutic goals in Fabry disease, based on expert consensus and evidence identified through a structured literature review. Biomarkers reflecting involvement of various organs in adult patients with classic Fabry disease are discussed and consensus recommendations for disease- and organ-specific therapeutic goals are provided. These consensus recommendations should support the establishment of individualized approaches to the management of patients with classic Fabry disease by considering identification, diagnosis, and initiation of disease-specific therapies before significant organ involvement, as well as routine monitoring, to reduce morbidity, optimize patient care, and improve patient health-related quality of life.

Cornea verticillata and acroparesthesia efficiently discriminate clusters of severity in Fabry disease

BACKGROUD

Fabry disease (OMIM #301 500), the most prevalent lysosomal storage disease, is caused by enzymatic defects in alpha-galactosidase A (GLA gene; Xq22.1). Fabry disease has historically been characterized by progressive renal failure, early stroke and hypertrophic cardiomyopathy, with a diminished life expectancy. A nonclassical phenotype has been described with an almost exclusive cardiac involvement. Specific therapies with enzyme substitution or chaperone molecules are now available depending on the mutation carried. Numerous clinical and fundamental studies have been conducted without stratifying patients by phenotype or severity, despite different prognoses and possible different pathophysiologies. We aimed to identify a simple and clinically relevant way to classify and stratify patients according to their disease severity.

METHODS

Based on data from the French Fabry Biobank and Registry (FFABRY; n = 104; 54 males), we applied unsupervised multivariate statistics to determine clusters of patients and identify clinical criteria that would allow an effective classification of adult patients. Thanks to these criteria and empirical clinical considerations we secondly elaborate a new score that allow the severity stratification of patients.

RESULTS

We observed that the absence of acroparesthesia or cornea verticillata is sufficient to classify males as having the nonclassical phenotype. We did not identify criteria that significantly cluster female patients. The classical phenotype was associated with a higher risk of severe renal (HR = 35.1; p <10-3) and cardiac events (HR = 4.8; p = 0.008) and a trend toward a higher risk of severe neurological events (HR = 7.7; p = 0.08) compared to nonclassical males. Our simple, rapid and clinically-relevant FFABRY score gave concordant results with the validated MSSI.

CONCLUSION

Acroparesthesia and cornea verticillata are simple clinical criteria that efficiently stratify Fabry patients, defining 3 different groups: females and males with nonclassical and classical phenotypes of significantly different severity. The FFABRY score allows severity stratification of Fabry patients.

FAbry STabilization indEX (FASTEX): Clinical evaluation of disease progression in Fabry patients

BACKGROUND

Two established scores, the Mainz Severity Score Index (MSSI) and Fabry Disease Severity Scoring System (DS3), quantify the disease burden in Fabry disease (FD), while the recent developed FAbry STabilization indEX (FASTEX) aims to detect disease progression.

OBJECTIVE

MSSI, DS3 and FASTEX were compared to evaluate disease stability or progression in a prospective cohort of Fabry patients under enzyme replacement therapy (ERT).

METHODS

Disease load of 62 patients (28 [45%] females) treated with ERT (26 [42%] under agalsidase-alfa) was assessed using the current scores and re-assessed after 12 months of treatment. Fifteen (24%) patients were ERT-naïve at baseline.

RESULTS

All scores showed a correlation with each other, while MSSI and DS3 showed the strongest (Pearson r: 0.81, p < .0001). Plasma lyso-Gb3 levels in naïve patients correlated with increasing DS3 and MSSI scores (Pearson r: 0.60, p < .05; Pearson r: 0.64, p < .01; respectively), but not with the total weighted FASTEX score. Longitudinal analysis suggested a stable disease course using DS3 and MSSI. Only males long-term-treated with agalsidase-alfa presented with a slight increase of the general MSSI score (p = .0084). By contrast, the FASTEX score demonstrates that only 21 patients (33.9%) were stable, all other patients presented a disease progression. Patients with an unstable FASTEX mainly suffered from a significant loss of renal function (eGFR_creat: -2.7 ± 7.3 ml/min/1.73 m², p = .0298).

CONCLUSION

We conclude that the FASTEX seems to be a simple and user friendly, valuable tool to assess early changes in disease progression even in smaller patient cohorts and short term surveillance.