New Therapeutics Options for Pediatric Neuromuscular Disorders

Seroprevalence of binding and neutralizing antibodies against 18 adeno-associated virus types in patients with neuromuscular disorders

High levels of pre-existing antibodies are a major challenge for the application of viral vectors since they can severely limit their efficacy. To identify promising candidates among adeno-associated virus (AAV) based vectors for future gene therapies for the treatment of hereditary neuromuscular disorders (NMDs), we investigated the antibody levels in sera from patients with NMDs against 18 AAV types, including 11 AAVs with wild-type capsids, 5 AAVs with peptide-modified capsids and 2 AAVs with shuffled capsids. With regard to the wild-type capsid AAVs, the lowest binding antibody levels were detected against AAV6, AAV5, AAV12 and AAV9, whereas the highest binding antibody levels were detected against AAV10, AAV8, AAV1, and AAV2. The lowest neutralizing antibody levels against wild-type AAVs were detected against AAV12, AAV5, AAV9, AAV7, AAV8 and AAV10, and the highest neutralizing antibody levels were detected against AAV13, AAV2 and AAV3. Interestingly, the influence of peptide modifications or shuffling of AAV capsids on antibody binding and AAV neutralization seemed to depend on the parental AAV. While the sex of the serum donors had no significant impact on binding or neutralizing antibody levels, we observed a trend to higher binding antibodies in older serum donors against some AAV types and a clear positive correlation of neutralizing antibody titers with the age of the serum donors. The disease status on the other hand did not have a meaningful impact on antibody levels, with no changes in AAV neutralization. Our data indicate that several wild-type or peptide-modified AAV may be good candidates for therapeutic application due to low pre-existing antibody levels, and that the age of potential recipients rather than their health status with regard to NMDs has the biggest impact on vector applicability.

'It gives me more freedom': Family perspectives on travelling with children on nocturnal ventilation

BACKGROUND

Children with neuromuscular weakness or central hypoventilation often require nocturnal ventilation. Children with these conditions are living longer and the numbers of children affected are increasing. The challenges associated with managing ventilation at home have been documented; however, there has been limited investigation into accessing wider experiences such as travel. Air travel, in particular, may be considered challenging for children with these conditions because oxygen levels are lower in airplane cabins than at sea levels.

OBJECTIVE

We sought to understand experiences of and attitudes towards travel amongst families of children using nocturnal ventilation for neuromuscular weakness or central hypoventilation.

METHODS

Two semi-structured interviews were conducted amongst participants enrolled in a trial of a new pre-flight assessment of their tolerance of reduced oxygen levels during flight (known as a hypoxic challenge test). Children participating in the trial were aged 19 months to 18 years. Parents were interviewed and provided proxy views for younger children, and older children were encouraged to present their own views during these interviews. One interview was conducted immediately after the assessment, and a second 3 months later. Data were analysed utilising the framework approach to thematic analysis.

RESULTS

Seventeen families participated in the first interview with 14 of these families completing the follow-up interview. Three further families participated in the follow-up interview only. Here, we report three themes relating to participant experience of travel and how this is impacted by their condition. The three themes and their sub-themes were (1) insight into children's lives: hospital attendances, gaining knowledge and confidence, and child as a person; (2) travelling with your child: planes, trains and automobiles, rules of air travel, and uncertainty; and (3) the meaning of travel: normalisation, connection to extended family, expanded experiences, and freedom and equality.

CONCLUSIONS

This population of children and their families aspire to travel but face challenges from clinical and social barriers. It is essential that we further our understanding of the physiological, social and cultural aspects of their experience to facilitate their access to broadened life experiences.

Inflammatory markers in cerebrospinal fluid of paediatric spinal muscular atrophy patients receiving nusinersen treatment

Spinal muscular atrophy (SMA) is a progressive motor neuron disease with onset during infancy or early childhood. Recent therapeutic advances targeting the genetic defect that underlies SMA improved survival in patients with infantile onset SMA (type 1) and improved motor function in SMA type 1-3. The most commonly used therapy for SMA, the antisense oligonucleotide nusinersen, is delivered by repeated intrathecal injections. The long-term safety effects of this procedure, however, have not yet been investigated in detail. We here present case reports of three children with SMA in which routine laboratory investigation revealed increased leukocyte counts in cerebrospinal fluid (CSF) collected during the course of nusinersen treatment. To further characterize this observation, we used a multiplex method to analyse a broad spectrum of inflammatory markers in the CSF of these patients. We found that interleukin-10 (IL10) was consistently elevated in CSF with increased leukocyte counts, but other inflammatory markers were not. Based on this analysis we selected 7 markers for further analysis in a cohort of 38 children with SMA and determined their expression during the course of nusinersen therapy. No consistent association was found between levels of inflammatory markers and the duration of nusinersen therapy in individual patients. However, monocyte chemoactive protein 1 (MCP1/CCL2) -a neuroprotective protein secreted by astrocytes and previously associated with SMA- levels increased over the course of nusinersen treatment, indicating a possible neuroprotective mechanism associated with nusinersen therapy. In summary, our findings confirm that repeated intrathecal injections are safe and do not trigger unwanted immune responses.

Seroprevalence of Binding and Neutralizing Antibodies against 39 Human Adenovirus Types in Patients with Neuromuscular Disorders

High pre-existing antibodies against viral vectors reduce their functionality and may lead to adverse complications. To circumvent this problem in future gene therapy approaches, we tested the seroprevalence of a large range of human adenovirus types in patients with neuromuscular disorders (NMDs) to find appropriate viral vector candidates for gene replacement therapy for NMDs. Binding and neutralizing antibodies against 39 human adenovirus types were tested in the sera of 133 patients with NMDs and 76 healthy controls aged 17-92 years. The influence of age, sex, and NMDs on antibody levels was analyzed. The seroprevalence of different adenoviruses in the cohort varied widely. The highest levels of binding antibodies were detected against HAdV-D27, -C1, -D24, -D70, -B14, -C6, -D13, -B34, and -E4, whereas the lowest reactivity was detected against HAdV-F41, -A31, -B11, -D75, -D8, -D65, -D26, -D80, and -D17. The highest neutralizing reactivity was observed against HAdV-B3, -C2, -E4, -C1, -G52, -C5, and -F41, whereas the lowest neutralizing reactivity was observed against HAdV-D74, -B34, -D73, -B37, -D48, -D13, -D75, -D8, -B35, and -B16. We detected no influence of sex and only minor differences between different age groups. Importantly, there were no significant differences between healthy controls and patients with NMDs. Our data show that patients with NMDs have very similar levels of binding and neutralizing antibodies against HAdV compared to healthy individuals, and we identified HAdV-A31, -B16, -B34, -B35, -D8, -D37, -D48, -D73, -D74, -D75, and -D80 as promising candidates for future vector development due to their low binding and neutralizing antibody prevalence.

The use of special approval medicines among pediatric patients in a tertiary care hospital: A reality check

Background

Special approval medicines (SAMs) are medicines used with approval from the Director General of Health Malaysia when the therapeutic options within regulatory and formulary boundaries appear unsuitable or ineffective to treat the patients.

Objectives

To examine and characterize the use of SAMs among children in a Malaysian tertiary care hospital.

Methods

The named-patient basis SAM application forms, cover letter, pharmacist review summary and patient monitoring forms available at the Pharmacy Department between 1st January 2019 and 31st December 2020 were reviewed. Unprocessed, unapproved and stock-basis applications were excluded. The outcome measures were categories, scope, off-label use and cost of SAM. Per-patient data were analyzed descriptively.

Results

Overall, 1010 patients (mean age of 8.7 ± 5.6 years) were involved in 328 SAMs applications. The most common SAMs pharmacological groups were nervous system (n = 371, 36.7%) and antineoplastic and immunomodulating agents (n = 332, 32.9%). Top three SAMs were melatonin (11.5%), scopolamine (7.6%) and cholecalciferol (7.1%). A total of 837 (82.9%) and 513 (50.8%) patients were involved in the SAMs applications for non-formulary and unregistered medicines, respectively. Unregistered, non-formulary medicines were applied for 47.3% (n = 478) of the patients. The majority of the scope for SAMs (64.7%) were to substitute the available alternatives in the national formulary which were ineffective or sub-optimal for the patients. Among the 262 patients with repeat applications, 93.8% reported disease or symptom improvement while 1.9% experienced side effects. Up to 17% of SAMs analyzed in this study were used for off-label indications. The total cost of the SAMs was RM8,748,358.38 (USD 2,090,418.86).

Conclusion

The use of SAMs among children in this hospital involved unregistered, non-formulary medicines used to substitute the available alternatives in the formulary. A concerted effort is warranted in exploring supplementary mechanisms to enhance the medicine registration process and formulary system towards facilitating enhanced provision of treatment for children.

Exogenous insulin-like growth factor 1 attenuates cisplatin-induced muscle atrophy in mice

BACKGROUND

A reduction in the skeletal muscle mass worsens the prognosis of patients with various cancers. Our previous studies indicated that cisplatin administration to mice caused muscle atrophy. This is a concern for human patients receiving cisplatin. The insulin-like growth factor 1 (IGF-1)/phosphoinositide 3-kinase (PI3K)/Akt pathway stimulates the rate of protein synthesis in skeletal muscle. Thus, IGF-I can be a central therapeutic target for preventing the loss of skeletal muscle mass in muscle atrophy, although it remains unclear whether pharmacological activation of the IGF-1/PI3K/Akt pathway attenuates muscle atrophy induced by cisplatin. In this study, we examined whether exogenous recombinant human IGF-1 attenuated cisplatin-induced muscle atrophy.

METHODS

Male C57BL/6J mice (8-9 weeks old) were injected with cisplatin or saline for four consecutive days. On Day 5, quadriceps muscles were isolated. Mecasermin (recombinant human IGF-1) or the vehicle control was subcutaneously administered 30 min prior to cisplatin administration. A dietary restriction group achieving weight loss equivalent to that caused by cisplatin administration was used as a second control. C2C12 myotubes were treated with cisplatin with/without recombinant mouse IGF-1. The skeletal muscle protein synthesis/degradation pathway was analysed by histological and biochemical methods.

RESULTS

Cisplatin reduced protein level of IGF-1 by about 85% compared with the vehicle group and also reduced IGF-1/PI3K/Akt signalling in skeletal muscle. Under this condition, the protein levels of muscle ring finger protein 1 (MuRF1) and atrophy gene 1 (atrogin-1) were increased in quadriceps muscles (MuRF1; 3.0 ± 0.1 folds, atrogin-1; 3.0 ± 0.3 folds, P < 0.001, respectively). The administration of a combination of cisplatin and IGF-1 significantly suppressed the cisplatin-induced downregulation of IGF-1/PI3K/Akt signalling and upregulation of MuRF1 and atrogin-1 (up to 1.6 ± 0.3 and 1.5 ± 0.4 folds, P < 0.001, respectively), resulting in diminished muscular atrophy. IGF-1 showed similar effects in cisplatin-treated C2C12 myotubes, as well as the quadriceps muscle in mice.

CONCLUSIONS

The downregulation of IGF-1 expression in skeletal muscle might be one of the factors playing an important role in the development of cisplatin-induced muscular atrophy. Compensating for this downregulation with exogenous IGF-1 suggests that it could be a therapeutic target for limiting the loss of skeletal muscle mass in cisplatin-induced muscle atrophy.

Reproductive genetic screening for information: evolving paradigms?

Reproductive genetic screening has introduced the possibility for pregnant women to learn, during the pregnancy or sometimes earlier, about the likelihood of their baby being affected with certain genetic conditions. As medicine progresses, the options afforded by this early information have expanded. This has led to a shifting paradigm in prenatal screening, wherein the early knowledge is seen as useful not solely for its inherent value to the pregnant woman, but also as enabling an expansion of conditions whose identification may allow early intervention and clinical impact. This article discusses this paradigm against the backdrop of prenatal genetic screening that is available today.

Antisense Oligonucleotide-Mediated Exon-skipping Therapies: Precision Medicine Spreading from Duchenne Muscular Dystrophy

In 1995, we were the first to propose antisense oligonucleotide (ASO)-mediated exon-skipping therapy for the treatment of Duchenne muscular dystrophy (DMD), a noncurable, progressive muscle-wasting disease. DMD is caused by deletion mutations in one or more exons of the DMD gene that shift the translational reading frame and create a premature stop codon, thus prohibiting dystrophin production. The therapy aims to correct out-of-frame mRNAs to produce in-frame transcripts by removing an exon during splicing, with the resumption of dystrophin production. As this treatment is recognized as the most promising, many extensive studies have been performed to develop ASOs that induce the skipping of DMD exons. In 2016, an ASO designed to skip exon 51 was first approved by the Food and Drug Administration, which accelerated studies on the use of ASOs to treat other monogenic diseases. The ease of mRNA editing by ASO-mediated exon skipping has resulted in the further application of exon-skipping therapy to nonmonogenic diseases, such as diabetes mellites. Recently, this precision medicine strategy was drastically transformed for the emergent treatment of only one patient with one ASO, which represents a future aspect of ASO-mediated exon-skipping therapy for extremely rare diseases. Herein, the invention of ASO-mediated exon-skipping therapy for DMD and the current applications of ASO-mediated exon-skipping therapies are reviewed, and future perspectives on this therapeutic strategy are discussed. This overview will encourage studies on ASO-mediated exon-skipping therapy and will especially contribute to the development of treatments for noncurable diseases.