Acid Sphingomyelinase Deficiency: Sharing Experience of Disease Monitoring and Severity in France

Acid sphingomyelinase deficiency (ASMD) is a rare inherited lipid storage disorder caused by a deficiency in lysosomal enzyme acid sphingomyelinase which results in the accumulation of sphingomyelin, predominantly within cells of the reticuloendothelial system located in numerous organs, such as the liver, spleen, lungs, and central nervous system. Although all patients with ASMD share the same basic metabolic defect, a wide spectrum of clinical presentations and outcomes are observed, contributing to treatment challenges. While infantile neurovisceral ASMD (also known as Niemann–Pick disease type A) is rapidly progressive and fatal in early childhood, and the more slowly progressive chronic neurovisceral (type A/B) and chronic visceral (type B) forms have varying clinical phenotypes and life expectancy. The prognosis of visceral ASMD is mainly determined by the association of hepatosplenomegaly with secondary thrombocytopenia and lung disease. Early diagnosis and appropriate management are essential to reduce the risk of complications and mortality. The accessibility of the new enzyme replacement therapy olipudase alfa, a recombinant human ASM, has been expedited for clinical use based on positive clinical data in children and adult patients, such as improved respiratory status and reduced spleen volume. The aim of this article is to share the authors experience on monitoring ASMD patients and stratifying the severity of the disease to aid in care decisions.


Introduction
Acid sphingomyelinase deficiency (ASMD) is an inborn error of metabolism that leads to the accumulation of sphingomyelin in cells and tissues causing the clinical condition also known as Niemann-Pick disease type A, A/B and B (NPD) [1]. In ASMD, the enzymatic deficiency of the lysosomal acid sphingomyelinase (ASM), is caused by pathogenic variants of the sphingomyelin phosphodiesterase 1 gene (SMPD1; EC 3.1.4.12). Sphingomyelin is a major structural component of all plasma membranes. Cellular physiological function requires ASM to catalyze the hydrolysis of sphingomyelin to ceramide and phosphocholine Ceramides have a proinflammatory effect as they are bioactive sphingolipids that act as second messengers which transduce pro-inflammatory signals.
Numerous variants of the SMPD1 gene, along with variability in residual ASM activity and other genetic/epigenetic factors, result in a spectrum of ASMD disease severity from a uniformly fatal form with death occurring by 3-4 years of age (ASMD type A or infantile neurovisceral ASMD previously known as NPD A) to chronic forms characterised by visceral (ASMD type B or chronic visceral ASMD, previously NPD B) and neurovisceral disease (ASMD type A/B chronic neurovisceral ASMD, previously NPD A/B) ( Table 1) [5][6][7]. Of note, while Niemann-Pick disease type C and ASMD share several phenotypic features, they represent two distinct disease entities [8]. Reliable estimates of the birth prevalence of ASMD are currently lacking [9]; however, an estimated birth prevalence of 0.4-0.6 per 100,000 births has been reported [10]. In France, the birth prevalence of the chronic visceral, non-neurological form is 1/230,000 births and is recognised as being an underdiagnosed disease (clinical experience suggests 150 patients diagnosed in France over the last 30 years) [11]. The clinical phenotype and life expectancy of patients with ASMD type B appears to vary, with many adults reaching a normal lifespan, while others die prematurely from ASMD-related complications, such as respiratory insufficiency and liver disease [1,5- Numerous variants of the SMPD1 gene, along with variability in residual ASM activity and other genetic/epigenetic factors, result in a spectrum of ASMD disease severity from a uniformly fatal form with death occurring by 3-4 years of age (ASMD type A or infantile neurovisceral ASMD previously known as NPD A) to chronic forms characterised by visceral (ASMD type B or chronic visceral ASMD, previously NPD B) and neurovisceral disease (ASMD type A/B chronic neurovisceral ASMD, previously NPD A/B) ( Table 1) [5][6][7]. Of note, while Niemann-Pick disease type C and ASMD share several phenotypic features, they represent two distinct disease entities [8]. Reliable estimates of the birth prevalence of ASMD are currently lacking [9]; however, an estimated birth prevalence of 0.4-0.6 per 100,000 births has been reported [10]. In France, the birth prevalence of the chronic visceral, non-neurological form is 1/230,000 births and is recognised as being an underdiagnosed disease (clinical experience suggests 150 patients diagnosed in France over the last 30 years) [11]. The clinical phenotype and life expectancy of patients with ASMD type B appears to vary, with many adults reaching a normal lifespan, while others die prematurely from ASMD-related complications, such as respiratory insufficiency and liver disease [1,[5][6][7]12]. Most patients with ASMD type B have interstitial lung disease with progressive impairment of pulmonary function, hepatosplenomegaly, haematological abnormalities (such as anaemia and thrombocytopenia) with bleeding, and an atherogenic lipid profile [7,9].
Data remain limited regarding predictors of disease-related morbidity, healthcare use, and lifestyle impact in patients with chronic ASMD; however, the physical, emotional, financial, and psychosocial burden of illness in patients with ASMD type B and ASMD type A/B is substantial [1,9,18,19]. McGovern et al. (2021) reported predictive factors of mortality that include both total splenectomy and spleen volume ≥15 multiples of normal (MN) at baseline [1]. Indeed, in an 11-year prospective natural history study of children and adults with ASMD, patients with a history of either severe splenomegaly or prior splenectomy had 10 times increased the likelihood of dying during follow up compared with those patients with moderate splenomegaly or intact spleens. On the contrary, liver volume of ≥2.5 MN was not shown to be a predictor of mortality. Interstitial lung disease was reported to worsen gradually with a mean diffusion capacity of carbon monoxide (DL CO ) decreasing below 50% of the predicted value in adult patients. Atherogenic lipid profiles typically worsen with age in patients with ASMD type B [5], and lipid abnormalities may be associated with early coronary artery disease [20].
Due to the rarity and heterogeneity of the disease, there is a lack of robust quantitative data regarding the impact of the disease on patients' and caregivers' quality of life (QoL), compounded by the lack of adequate disease-specific instruments to measure QoL [9].

Clinical Study Evidence for the Use of Olipudase Alfa in the Non-Neurologic Manifestations of ASMD
Knockout mouse models have demonstrated that enzyme replacement therapy (ERT) is likely to be a useful therapeutic approach for patients with non-neurological ASMD, with a strong response to ERT in the major organs involved in the disease (liver, spleen, and lung) [21]. For the neurological manifestation of ASMD, ERT is unlikely to evoke any therapeutic response in the central nervous system since it does not cross the bloodbrain barrier. Importantly, progressive dose escalation appeared essential to prevent the possibility of a deadly cytokine storm due to the abrupt release of high levels of ceramide [22].
Olipudase alfa is currently being investigated as an ERT for the treatment of the nonneurological manifestations of ASMD [21,23]. Of note, olipudase alfa is the first and only investigational ERT in late-stage development for ASMD. Olipudase alfa acts by targeting the underlying metabolic defect by supplementing the deficient enzyme activity [24].
A Phase 1A study assessed the infusion of a single dose (0.03-1.0 mg/kg) of olipudase alfa in 11 patients with ASMD type B [25]; a maximum starting dose of 0.6 mg/kg was identified which supported a dose-escalation strategy for the gradual clearance of accumulated sphingomyelin which was applied in a Phase 1B study. Of note, the aim of the dose-escalation process of olipudase alfa is gradual sphingomyelin debulking to prevent high ceramide release ( Figure 1). Blood ceramide levels increased up to five-fold (both doseand time-dependent), beginning 2-6 h after infusion, peaking between 24 and 48 h and returning to pre-infusion levels by Day 14. This led to systemic inflammation illustrated by high levels of C-reactive protein and bilirubin reported in patients who received the highest dosages of olipudase alfa (i.e., 0.6 and 1.0 mg/kg). No serious adverse drug reactions occurred during the study.
A Phase 1B study assessed safety and tolerability of olipudase alfa in five patients with ASMD type B reported no death, serious or severe adverse events (AEs), or AEs leading to discontinuation over the 26-week study period [26]; most AEs were mild (97%) and resolved without sequelae and all patients were successfully escalated to the maximum study dose of 3.0 mg/kg. A positive therapeutic response was also observed in liver sphingomyelin content, spleen and liver volumes, along with improvements in infiltrative lung disease, lipid profiles, platelet counts, and QoL. A sustained safety profile and continued improvements in clinically relevant parameters following up to 42 months of treatment in these patients has been reported [26][27][28].
A long-term safety study (NCT02004704) has demonstrated that olipudase alfa provides improvements in lipid profiles up to 42 months [28][29][30]; these include progressive reductions from baseline in pro-atherogenic lipid profiles (total cholesterol, low-density lipoprotein cholesterol [LDL-C], very low-density lipoprotein cholesterol, triglycerides) and progressive increases in anti-atherogenic markers (high-density lipoprotein cholesterol and apolipoprotein A-I).
Two separate clinical studies evaluating olipudase alfa for the treatment of chronic ASMD in adult and paediatric patients have also demonstrated positive results [27,31]. The Phase I/II open label, ascending dose, multicentre ASCEND-Peds study (NCT02292654) evaluated the safety, tolerability, and pharmacokinetics of olipudase alfa in 20 paediatric patients with chronic visceral ASMD over a 64-week study period [27]. A clinically meaningful improvement in pulmonary function assessed by the DLco and reduction in spleen size were reported-after 52 weeks of treatment, mean spleen volume decrease was shown to be 49%, while the nine patients who were able to perform the DLco test showed a mean increase of 33%. Most AEs were mild to moderate in severity, and no permanent treatment discontinuations were reported. The ongoing Phase II/III randomised, double-blind, placebo-controlled ASCEND (adults) study (NCT02004691) evaluated the efficacy, safety, and pharmacokinetics/pharmacodynamics of olipudase alfa in 36 adults with chronic visceral ASMD over a 52-week primary analysis period, which is now being followed by an extension period (all treated patients) of up to 4 years [31]. Patients received either olipudase alfa intravenous infusion or placebo every two weeks at an escalating dose from 0.1 mg/kg up to 3 mg/kg administered every two weeks. Figure 2 shows the dose-escalation strategy used in the ASCEND (adults) and ASCEND-Peds studies. The ASCEND (adults) study assessed two independent primary efficacy endpoints: DLco and spleen volume to reflect the separate critical manifestations of chronic visceral ASMD, with the trial outcome being deemed positive if one of these endpoints was met. Treatment outcomes favoured olipudase alfa (vs placebo) at Week 52 for spleen volume, percentage predicted DLco, liver volume and platelet levels. Overall, spleen volume was significantly decreased by 39.5% in the olipudase alfa arm compared with a 0.5% increase in the placebo arm (40% difference; p < 0.0001). In addition, percent change from baseline in percentage predicted DLco was +22% for the olipudase alfa arm at Week 52 compared with +3% for the placebo arm (19% difference; p = 0.0004). In addition, all treatment-related AEs were mild-to-moderate in severity and no patients discontinued due to AEs [19].
In 2015, the US Food and Drug Administration granted a breakthrough therapy designation to olipudase alfa based on the Phase 1b study data, an approach used to expedite the development and review of drugs intended to treat serious or life-threatening diseases and conditions [32]. Similarly, in 2016, olipudase alfa has gained orphan designation and 'PRIority Medicines' (PRIME) designation by the European Medicines Agency, along with being awarded the SAKIGAKE designation in Japan, in order to expedite the regulatory process [33].  [31]. The aim of the dose-escalation process of olipudase alfa is gradual sphingomyelin debulking to prevent high ceramide release. BMI, body mass index. (B) Dose escalation regimen for pediatric patients administered every 2 weeks. Dose escalation regimen of olipudase alfa phase I/II ASCEND PEDS [27].
In 2015, the US Food and Drug Administration granted a breakthrough therapy designation to olipudase alfa based on the Phase 1b study data, an approach used to expedite the development and review of drugs intended to treat serious or life-threatening diseases and conditions [32]. Similarly, in 2016, olipudase alfa has gained orphan designation and 'PRIority Medicines' (PRIME) designation by the European Medicines Agency, along with being awarded the SAKIGAKE designation in Japan, in order to expedite the regulatory process [33].

Materials and Methods
Four expert meetings took place in Paris from 2019 to 2021, followed by several teleconferences, to gather expert opinion of French physicians with regards to the monitoring and severity stratification of children and adult patients with ASMD types B and A/B. All authors participated in the meetings apart from W.M. W.M., O.L., and A.B. have coordinated the process of early access to treatment in French ASMD patients. All co-authors have worked on this process.

General Care of Patients with ASMD Type B Forms
Treatment goals for patients with chronic visceral ASMD should focus on reducing spleen and liver volumes, limiting hepatic fibrosis, decreasing cytopenia, improving liver function tests, and respiratory status in order to decrease morbidity and mortality [12]. However, the current management of ASMD type B has been limited to supportive care and palliation [9,13,34].
Regardless of aetiology, any respiratory failure should be treated with oxygen and respiratory rehabilitation [9,35,36]. Patients should also be encouraged to stop or avoid smoking (including second-hand exposure), to reduce the risk of lung and coronary disease, as well as cancer [13,37]. There is no specific recommendation but standard lipidlowering agents, such as statins or ezetimibe, have shown benefits and are classically proposed to manage blood lipid abnormalities [9,13,38].
While there is no available treatment shown to improve bone density in patients with ASMD type B, the use of regular calcium and vitamin D supplementation to support healthy bone function is recommended [9]; of note, the use of bisphosphonates should be avoided given their potent inhibition of ASM [39].  [31]. The aim of the dose-escalation process of olipudase alfa is gradual sphingomyelin debulking to prevent high ceramide release. BMI, body mass index. (B) Dose escalation regimen for pediatric patients administered every 2 weeks. Dose escalation regimen of olipudase alfa phase I/II ASCEND PEDS [27].

Materials and Methods
Four expert meetings took place in Paris from 2019 to 2021, followed by several teleconferences, to gather expert opinion of French physicians with regards to the monitoring and severity stratification of children and adult patients with ASMD types B and A/B. All authors participated in the meetings apart from W.M. W.M., O.L., and A.B. have coordinated the process of early access to treatment in French ASMD patients. All co-authors have worked on this process.

General Care of Patients with ASMD Type B Forms
Treatment goals for patients with chronic visceral ASMD should focus on reducing spleen and liver volumes, limiting hepatic fibrosis, decreasing cytopenia, improving liver function tests, and respiratory status in order to decrease morbidity and mortality [12]. However, the current management of ASMD type B has been limited to supportive care and palliation [9,13,34].
Regardless of aetiology, any respiratory failure should be treated with oxygen and respiratory rehabilitation [9,35,36]. Patients should also be encouraged to stop or avoid smoking (including second-hand exposure), to reduce the risk of lung and coronary disease, as well as cancer [13,37]. There is no specific recommendation but standard lipid-lowering agents, such as statins or ezetimibe, have shown benefits and are classically proposed to manage blood lipid abnormalities [9,13,38].
While there is no available treatment shown to improve bone density in patients with ASMD type B, the use of regular calcium and vitamin D supplementation to support healthy bone function is recommended [9]; of note, the use of bisphosphonates should be avoided given their potent inhibition of ASM [39].
Due to the low platelet count and splenomegaly, contact sports (particularly those with a risk of abdominal impact) should be avoided [9]. Splenectomy should be avoided as it has been demonstrated to increase the risk of lung disease and overall mortality [5].
Optimised immunisation in ASMD patient population is challenging because of a data gap in vaccine trials. Vaccinations against pneumococci, Haemophilus influenzae type B, meningococci, and influenza virus are recommended for patients with anatomic or functional asplenia [9,13,40]. While the use of the meningitis vaccine is mandatory in paediatric patients, its use in adult patients is also mandatory in patients with anatomic or functional asplenia [41]. In adult patients with platelets >30 G/L, vaccination against COVID-19 should now empirically be offered, as with all patients with a higher risk of severe COVID-19 due to chronic lung and/or liver disease [42].

Monitoring of Patients with ASMD Type B Forms
Scheduled patient monitoring remains essential to manage symptoms as early as possible, in order to minimise the risk of poor clinical outcomes. Based on our experience, a summary of key monitoring parameters along with the frequency of assessment for patients with ASMD type B are shown in Table 2 (pulmonary, hepato-splenic, and haematological assessments) and Table 3 (summary of all monitoring parameters). It is recommended that patient monitoring would be undertaken by a multidisciplinary team in an experienced centre (referral or competence centre in France). As with other diseases, the frequency of monitoring must be determined by patient severity and assessment results, as well as the progression of the disease.
Given the future availability of ERT, there is a need for biomarkers that predict or reflect disease progression [17]; suitable markers need to be validated for their use as surrogate markers of clinically relevant endpoints. Eskes et al. (2020) highlighted that the best evaluated potential biomarkers for ASMD are DLco, spleen volume, platelet count, LDL-C, liver fibrosis (measured with fibroscan) and lysosphingomyelin [17]. Our opinion is that the biomarkers chitotriosidase, lysosphingomyelin, and lysosphingomyelin 509 should be assessed at baseline, with follow up every 3 or 6 months for the first year, and then every year ( Table 3).
Given that ASMD is an autosomal recessive inherited condition, carrier testing for at-risk relatives, prenatal testing for a pregnancy at increased risk, and preimplantation genetic testing are all possible, following the identification of a SMPD1 pathogenic variant in an affected family member [43,44]. In general, there is no specific complication during pregnancy in patients with ASMD type B; although, episodes of bleeding have been reported. ASMD type A is the most severe form of ASMD with rapidly progressive neurovisceral manifestations and fatal issues with multisystem involvement. For ASMD type A, prenatal diagnosis is routinely accomplished by mutational analysis when an index case is identified in the family [43].   Monitoring frequency in adults: to be considered at initial assessment according to the clinical context and the neuropsychological tests Monitoring frequency in children: to be carried out at initial assessment if the diagnosis is made at a very early stage of childhood

Ophthalmic assessment
Ocular fundus At initial assessment The macular cherry-red spot is present in all patients with form A, and has been reported in one third of patients with form B [20] Visual acuity At initial assessment Loss of visual acuity in infantile type (no effect in chronic visceral ASMD)

Other
Dermatological examination At initial assessment and then annually Necessary in order to assess the presence of lymphoedema (eyelid infiltration) TSH assay (in combination with anti-TPO antibodies) At initial assessment and then annually Necessary for the investigation of thyroid autoimmunity

Patients with ASMD: Stratification by Disease Severity
In France, the exceptional use of proprietary medicinal products which do not have a marketing authorisation and are not the subject of a clinical trial can occur under the following three conditions: (1) specialties are intended to treat, prevent, or diagnose serious or rare diseases; (2) there is no appropriate treatment available on the market; and (3) their efficacy and safety of use are presumed in the state of scientific knowledge and the implementation of the treatment cannot be postponed [45]. This exceptional so-called 'Temporary Use Authorisation' (TUA) is delineated by specific criteria that have to be defined according to the results of the different trials and the criteria of the expected future marketing authorisation.
Where treatment is warranted based on disease severity, early access to olipudase alfa can be possible based on the following conditions: (1) the patient or person of trust must be informed of the exceptional and critical nature of this requirement; (2) specialties are intended to treat, prevent, or diagnose serious or rare diseases; (3) there is no appropriate treatment available on the market; (4) the patient cannot be included in a clinical trial; and (5) the effectiveness and safety of use of the prescribed treatment are not only presumed in the state of scientific knowledge and the implementation of the processing cannot be postponed.
In order to define the access criteria to the TUA procedure, the Therapeutic Evaluation Committee for Visceral Lipidoses (CETLv) in France convened a disease severity classification of patients with ASMD type B or A/B, i.e., via the Brassier-Lidove classification (Table 4). Worsening dyspnoea, low platelets <50 G/L and/or recurrent bleeding, biological and/or histological liver damage, and painful splenomegaly are key features of severe disease. Important clinical criteria in paediatric patients include a break in the growth curve or painful splenomegaly (Figure 3). Table 4. Patients with chronic ASMD grouped among disease severity (CETLv classification).

Group Definition
Group outside the early access spectrum application ASMD types B and A/B (NPD B or A/B) with a short-term vital prognosis (e.g., cancer) appropriate treatment available on the market; (4) the patient cannot be included in a clinical trial; and (5) the effectiveness and safety of use of the prescribed treatment are not only presumed in the state of scientific knowledge and the implementation of the processing cannot be postponed.
In order to define the access criteria to the TUA procedure, the Therapeutic Evaluation Committee for Visceral Lipidoses (CETLv) in France convened a disease severity classification of patients with ASMD type B or A/B, i.e., via the Brassier-Lidove classification (Table 4). Worsening dyspnoea, low platelets <50 G/L and/or recurrent bleeding, biological and/or histological liver damage, and painful splenomegaly are key features of severe disease. Important clinical criteria in paediatric patients include a break in the growth curve or painful splenomegaly (Figure 3). Table 4. Patients with chronic ASMD grouped among disease severity (CETLv classification).

Group
Definition Group outside the early access spectrum application ASMD types B and A/B (NPD B or A/B) with a short-term vital prognosis (e.g., cancer)  During nominative early access to olipudase alfa the Brassier-Lidove classification (CETLv classification) ( Table 4) has been applied. Of 29 adult patients from the Croix Saint-Simon Hospital (Paris, France), two were deemed to be outside the early access application because of a limited life expectancy, two were in CETLv Group 1 and were too severely affected to participate in ASCEND trial (Table 5) (one patient with symptomatic thrombocytopenia <40 G/L and one patient with severe pulmonary failure awaiting lung transplantation), two were in CETLv Group 2 (both patients were participating in the ASCEND study), eight patients were in CETLv Group 3 (including two patients receiving psychotropic drugs), ten patients were in CETLv Group 4, and five patients in CETLv Group 5. Of this patient cohort, 10/29 (34.5%) patients were deemed to be eligible for olipudase alfa via ATU according to the CETLv classification. In the Referral Center for Inherited Diseases of Metabolism at the Hospices Civils of Lyon (Lyon, France), there have been two children treated since 2015 and 2018 as part of the pediatric clinical trial and two children treated as part of a nominative ATU (Group 1). Two adults have also been treated in the ATU for severe lung damage (Group 1).

Early Access Experience to ERT in France
Prior to full marketing authorisation, as of 14 October 2021, compassionate use of olipudase alfa was initiated in France in 4 nominative pediatric patients and 19 adult patients. A total of 14 physicians originating from 12 different cities (Lyon, Clermont-Ferrand, Bordeaux, Angers, Paris, Marseille, Quimper, Clichy, Strasbourg, Lille, Toulouse, and Caen) are currently treating ASMD patients, at the rate of about 1 to 5 patients per center. Of note, 16 out of these 23 patients were initiated with olipudase alfa by the co-authors of this work. Dose escalation (Figure 2) was conscientiously followed.

Discussion
In ASMD, as the lysosomal sphingomyelinase enzymatic defect is expressed ubiquitously throughout the organs, improvement in one tissue may be considered as representative of an overall improvement in non-neurological clinical status.
Available evidence from the natural history of ASMD and observational studies support the use of DLco and splenomegaly as clinically meaningful endpoints that assess disease burden for patients. Worsening DLco is a strong indicator of progressive lung disease in chronic visceral ASMD, contributing to increased disease burden. Likewise, spleen volume may be considered as a surrogate marker for bleeding risk and liver disease. Pneumonia/respiratory failure, and/or liver failure, are often the causes of death [9].
The main clinical criteria that were considered in France to prioritise early access to treatment with olipudase alfa in patients with ASMD type B or type A/B are low DLco with worsening dyspnoea, thrombocytopenia <50 G/L or recurrent bleeding, biological and/or histological liver damage, and painful splenomegaly (Figure 3), and in the case of paediatric patients a break in the growth curve or painful splenomegaly should be considered ( Figure 3). Thus, a complete evaluation of the patient prior treatment initiation is mandatory in order to assess the potential benefit of olipudase alfa on the spleen volume, respiratory function, and platelet count, as well as any possible issues related to tolerance and comorbidities, such as tobacco use. In addition, as lung, spleen, liver, platelet status, and growth curve can worsen, a regular follow up with clinical, biological, and morphological of pauci/asymptomatic patients must be performed. The CETLv stratification of severity may aid the physician in health care decisions.
Data from the ASCEND (adult) and ASCEND-Peds (paediatric) studies have demonstrated that olipudase alfa can improve respiratory status and reduce spleen volume in patients with visceral ASMD (Table 5) [27,31]. In addition, the clinical relevance of the endpoints used in these studies is well documented [46]. Of note, patients included in the ASCEND (adult) and ASCEND-Peds studies did not exhibit the full spectrum of severity in patients with ASMD, excluding asymptomatic individuals and those with very severe disease. After dose escalation, steady-state dose infusions, and record of adequate tolerance to olipudase alfa, home therapy with a multidisciplinary team and regular follow-up should be considered. An 'emergency card' delivered to the patient could be helpful to improve the communication between the patient, and home and hospital caregivers in patients in home infusion.
The present early experience can be used as the basis for further clinical evaluations.

Conclusions
The management of chronic visceral and ASMD type B and A/B has traditionally been limited to supportive care and palliation. Clinical studies in patients with chronic ASMD have demonstrated positive results with the novel ERT olipudase alfa, comprising improvement in respiratory status and spleen volume reduction, as well as improvement in other clinical manifestations. In France, low DLco with worsening dyspnoea, thrombocytopenia <50 G/L or recurrent bleeding, biological and/or histological liver damage, and painful splenomegaly have been used to prioritise early compassionate use of olipudase alfa in nominative paediatric and adult patients with ASMD. Of note, the use of any decisionmaking process/stratification for patients with ASMD need to be confirmed by 'real-life' evidence. In addition, scheduled follow up of treated patients outside clinical trials is mandatory to assess the effect of olipudase alfa in those individuals with chronic ASMD. Regular follow up must be performed in untreated patients with ASMD. Asymptomatic patients should be evaluated by experts on a 'case-by-case' basis to ensure opportune early treatment initiation.