STEP® vectors for rapid generation of stable transfected CHO cell pools and clones with high expression levels and product quality homogeneity of difficult-to-express proteins

Many proteins produced in CHO cells need evaluation for their clinical and commercial potential. Traditional methods based on stable clone generation are slow and unsuitable for screening larger numbers of proteins, while transient expression technologies are fast but unpredictable regarding product quality and lacking an optional path to subcloning. The STEP® vector technology introduced here combines the best properties of both methods. STEP® vectors contain a strong transcriptional cassette driving expression of a bicistronic mRNA. The gene-of-interest (GOI) is cloned upstream of a functionally impaired zeocin resistance gene (FI-Zeo) whose translation is coupled to that of the GOI through an IRES. Stable transfected cells surviving zeocin selection produce high levels of FI-Zeo and thus, high levels of the GOI-encoded protein. By using different spacers, the translational coupling efficiency and selection strength can be controlled allowing maximization of expression of any GOI. Production of laronidase and factor VII (FVII) is presented as examples of unrelated, difficult-to-express (DTE) proteins. First step is rapid generation of transfected pools with the STEP® vectors. All high expressing surviving pools showed high product quality homogeneity as did monoclonal cell lines obtained from the top pools. Up to 500 μg/mL laronidase was obtained with virtually identical glycosylation profile as reference product. For FVII, cell specific productivity of 0.45 pg/cell/day with 50 IU/μg protein matched highest reported levels of reference product even before process development. Taken together, STEP® vector technology is ideally suited for rapid, small to large-scale production of DTE proteins compared to traditional methods.

The multi-domain responder index: a novel analysis tool to capture a broader assessment of clinical benefit in heterogeneous complex rare diseases

In traditional clinical trial design, efficacy is typically assessed using a single primary endpoint in a randomized controlled trial to detect an expected treatment effect of a therapy in a narrowly selected patient population. This accepted paradigm is based on clinical evaluations that may not actually capture the breadth of the impact of a disease, which is especially true in the setting of complex, multisystem, rare diseases with small, extremely heterogeneous patient populations. The multi-domain responder index (MDRI) is a novel approach that accommodates complex and heterogeneous disease manifestations and evaluates a broad array of clinical disease without impairing the power or rigor of a study to fully understand a treatment. The MDRI sums the scores corresponding to clinically significant thresholds of change for each component domain in each individual patient, capturing the mean clinically meaningful change across multiple domains within individuals. This novel approach combines and then sums the results of independent domain endpoint responder analyses into one responder score to provide a broad basis for the assessment of efficacy. The impact of a treatment across multiple, physiologically independent domains, can be assessed clinically, reducing the adverse impact of heterogeneity on trial outcomes and allowing eligibility criteria to enroll a wider range of patients, ultimately resulting in efficacy and safety assessments of a therapy across a broad group of heterogeneous patients in rare disease programs.

Trial registration The following studies are referenced within this manuscript (CLINICALTRIALS.GOV registration numbers): NCT00912925; NCT00146770; NCT00067470; NCT00104234; NCT00069641; NCT02230566; NCT02377921; NCT02432144.

International working group identifies need for newborn screening for mucopolysaccharidosis type I but states that existing hurdles must be overcome

Aim

Mucopolysaccharidosis type I is a lysosomal storage disorder that can result in significant disease burden, disability and premature death, if left untreated. The aim of this review was to elaborate on the diagnosis of mucopolysaccharidosis type I and the pros and cons of newborn screening.

Methods

An international working group was established to discuss ways to improve the early diagnosis of mucopolysaccharidosis type I. It consisted of 13 experts in paediatrics, rare diseases and inherited metabolic diseases from Europe and the Middle East.

Results

It is becoming increasingly clearer that the delay between symptom onset and clinical diagnosis is considerable for mucopolysaccharidosis type I and other rare lysosomal storage disorders, despite numerous awareness campaigns since therapies became available. Diagnosis currently depends on recognising the signs and symptoms of the disease. The practice of newborn screening, which is being explored by pilot programmes around the world, enables early diagnosis and consequently early treatment. However, these studies have highlighted numerous new problems and pitfalls that must be faced before newborn screening becomes generally available.

Conclusion

Newborn screening for mucopolysaccharidosis type I offers the potential for early diagnosis and early pre‐symptomatic treatment, but existing hurdles need to be overcome.

Efficacy of laronidase therapy in patients with mucopolysaccharidosis type I who initiated enzyme replacement therapy in adult age. A systematic review and meta-analysis

BACKGROUND

The efficacy of starting enzyme replacement therapy (ERT) in adults with Muchopolysaccharidosis Type I (MPS-I) is controversial. Evaluating the benefits reported by patients initiating ERT with laronidase at adult age might help physicians decide whether the use of ERT in these patients is worthwhile from a clinical point of view.

OBJECTIVE

To assess every effectiveness variable modified in MPS-I patients who initiated laronidase at adult age.

METHODS

A systematic search of the literature, from inception to July 2016, was conducted using MEDLINE, EMBASE, CENTRAL and LILACS to identify randomized trials or observational studies including ≥1 MPS-I patients with ERT initiated in adult age (≥18years) and evaluating ERT efficacy. A meta-analysis of studies evaluating the same effectiveness outcome was performed and the evidence was rated according to GRADE criteria. Heterogeneity was assessed by the Chi-squared test and the I-squared statistic. Case reports were excluded from meta-analysis but their main outcomes were separately evaluated. The decrease in urine glycosaminoglycans (uGAGs) levels as patient percentage with reduction in uGAGs and with normalization was the primary outcome.

RESULTS

Nineteen clinical studies and 12 case reports were selected. ERT decreased uGAG levels (high evidence) and liver volume (high), improved 6-min walking test (6MWT) (moderate) and increased blood anti-ERT antibody levels (high). There was no conclusive results (low or very low evidence) regarding improvement/stabilization of respiratory function, change in shoulder flexion, cardiac improvement/stabilization, improvement in symptoms of nocturnal hypoventilation and sleep apnea, improvement in quality of life, visual acuity, otolaryngologic function, bone mineral density or effectiveness of intrathecal therapy.

LIMITATIONS

Excluding case reports, there was no study conducted specifically in the target population (ERT ≥18years). Data were from subgroup analyses of selected studies. There was a great heterogeneity between designs and clinical outcomes evaluated.

CONCLUSIONS

ERT improves uGAGs and liver volume in MPS-I patients initiating therapy as adults, although the putative clinical benefit associated to these improvements is unclear. Moderate evidence was shown for improvement in 6MWT. Systematic review registration number (PROSPERO): 42,016,041,306.

Immune tolerance induction for laronidase treatment in mucopolysaccharidosis I

Enzyme replacement therapy (ERT) can produce anti-drug antibody (ADA) responses that reduce efficacy or lead to hypersensitivity reactions. Six patients with severe mucopolysaccharidosis type I (MPS I/Hurler syndrome) who did not receive hematopoietic stem cell transplantation underwent an immunosuppression regimen prior to initiating ERT with laronidase. The primary endpoint for immune tolerance induction was the number of patients with an ADA titer ≤ 3200 after 24 weeks of laronidase at the labeled dose. Cyclosporine levels were measured weekly and doses adjusted to maintain trough levels above 400 mg/mL. A 6-week (Cohort 1) or 12-week (Cohort 2) immune tolerance induction period with cyclosporine (initial dose: 15 or 20 mg/kg/day), azathioprine (initial dose: 2.5 or 5 mg/kg/day) and low-dose laronidase infusions (0.058–0.29 mg/kg/week) was followed by an immune-challenge period with laronidase infusions at the labeled dose (0.58 mg/kg/week) for 24 weeks. Anti-laronidase IgG titers were determined following treatment. There were 147 treatment-emergent adverse events reported, most of which were mild and not related to the study treatment. While there was no evidence of immune tolerance in 3 of 3 patients in Cohort 1, there were some indications of immune tolerance induction in 2 of 3 patients in Cohort 2. Patients with lower ADA titers showed greater reductions in urinary glycosaminoglycan excretion. Routine monitoring of plasma cyclosporine parent-compound levels by high pressure liquid chromatography proved difficult for clinical practice. The evolving clinical management of MPS I and a better understanding of the clinical impact of laronidase-related immunogenicity require reassessment of immune modulation strategies in patients with MPS I receiving laronidase treatment. Clinical Trial Registration: NCT00741338.

Effect of anti-laronidase antibodies on efficacy and safety of laronidase enzyme replacement therapy for MPS I: A comprehensive meta-analysis of pooled data from multiple studies

Enzyme replacement therapy (ERT) with laronidase has an important role in the treatment of patients with mucopolysaccharidosis type I (MPS I). Laronidase is safe and has demonstrated effectiveness in terms of stabilizing or improving conventional clinical and laboratory markers of the disease. However, like most ERTs, laronidase produces an anti-drug IgG antibody response in more than 90% of patients during the first few months of treatment. Preclinical data from the MPS I canine model suggest that anti-drug antibodies (ADA) impair enzyme uptake in target tissues. In patients, the effects on tissue glycosaminoglycan (GAG) clearance are difficult to assess directly but data from clinical studies have suggested an association between ADA and both a reduced pharmacodynamic response and hypersensitivity reactions. This comprehensive meta-analysis of pooled data from patients in three clinical studies of laronidase (including one study with an extension) was undertaken to provide a more robust assessment of the relationship between the ADA response to laronidase, clinical and laboratory markers of MPS I, and hypersensitivity reactions. The meta-analysis demonstrated an inverse relationship between the ADA response and the percent reduction in urinary GAG (uGAG) levels. However, no relationships between the ADA response and changes in percent predicted forced vital capacity and six-minute walk test were seen. The study also re-assayed stored serum samples from the original trials with a novel method to determine the inhibitory effect of ADA. Patients with higher ADA exposure over time were found to have higher inhibition of enzyme uptake into cells. High ADA exposure can result in a commensurate level of enzyme uptake inhibition that decreases the pharmacodynamic effect of the exogenously administered therapeutic enzyme, but with no clear effect on clinical efficacy.

The impact of laronidase treatment in otolaryngological manifestations of patients with mucopolysaccharidosis

Introduction

Mucopolysaccharidosis (MPS) is a lysosomal storage disease caused by deficiency of α-l-iduronidase. The otolaryngological findings include hearing loss, otorrhea, recurrent otitis, hypertrophy of tonsils and adenoid, recurrent rhinosinusitis, speech disorders, snoring, oral breathing and nasal obstruction.

Objective

To evaluate the impact of enzymatic replacement therapy with laronidase (Aldurazyme^®) in patients with mucopolysaccharidosis (MPS I), regarding sleep and hearing disorders, and clinical manifestations in the upper respiratory tract (URT).

Methods

Nine patients with MPS I (8 Hurler-Scheie, and 1 Scheie phenotypes) of both sexes, ages ranging between 3 and 20 years, were included in this study. Patients were evaluated between seven and 11 months before the treatment and between 16 and 22 months after the onset of the enzymatic replacement. They were all submitted to a clinical and otolaryngological evaluation, including nasofibroscopical, polysomnographic and audiologic exams.

Results

The results’ data showed decreasing of the frequency of ear, nose and throat infections, with improvement of the rhinorrhea and respiratory quality. No remarkable changes were observed regarding macroglossia and tonsil and adenoid hypertrophy. Audiometric and polysomnographic evaluations did not show statistical significance.

Conclusion

Enzymatic replacement therapy in patients with mucopolysaccharidosis I provides control of recurrent URT infections, rhinorrhea and respiratory quality, however it is does not seem to improve audiologic and polisomnographic parameters, with no effect on adenoid and tonsils hypertrophy and macroglossia.

Enzyme replacement therapy in Hurler syndrome after failure of hematopoietic transplant

The most severe form of Mucopolysaccharosidosis type I (MPS-I), Hurler syndrome, presents with progressive respiratory, cardiac and musculoskeletal symptoms and cognitive deterioration.

Treatment includes enzyme replacement therapy (ERT) and/or hematopoietic stem cell transplantation (HSCT).

We describe the case of an 8-year old boy with MPS-I, homozygous for W402X, treated at 10 months of age with HSCT and after failure of the transplant, with ERT during 2 years showing good results, including a positive neuropsychological development.

Biomarker responses correlate with antibody status in mucopolysaccharidosis type I patients on long-term enzyme replacement therapy

BACKGROUND

Antibody formation can interfere with effects of enzyme replacement therapy (ERT) in lysosomal storage diseases. Biomarkers are used as surrogate marker for disease burden in MPS I, but large systematic studies evaluating the response of biomarkers to ERT are lacking. We, for the first time, investigated the response of a large panel of biomarkers to long term ERT in MPS I patients and correlate these responses with antibody formation and antibody mediated cellular uptake inhibition.

METHODS

A total of 428 blood and urine samples were collected during long-term ERT in 24 MPS I patients and an extensive set of biomarkers was analyzed, including heparan sulfate (HS) and dermatan sulfate (DS) derived disaccharides; total urinary GAGs (DMBu); urinary DS:CS ratio and serum heparin co-factor II thrombin levels (HCII-T). IgG antibody titers and the effect of antibodies on cellular uptake of the enzyme were determined for 23 patients.

RESULTS

Median follow-up was 2.3 years. In blood, HS reached normal levels more frequently than DS (50% vs 12.5%, p=0.001), though normalization could take several years. DMBu normalized more rapidly than disaccharide levels in urine (p=0.02). Nineteen patients (83%) developed high antibody titers. Significant antibody-mediated inhibition of enzyme uptake was observed in 8 patients (35%), and this correlated strongly with a poorer biomarker response for HS and DS in blood and urine as well as for DMBu, DS:CS-ratio and HCII-T (all p<0.006).

CONCLUSIONS

This study shows that, despite a response of all studied biomarkers to initiation of ERT, some biomarkers were less responsive than others, suggesting residual disease activity. In addition, the correlation of cellular uptake inhibitory antibodies with a decreased biomarker response demonstrates a functional role of these antibodies which may have important clinical consequences.

Early initiation of enzyme replacement therapy for the mucopolysaccharidoses

The mucopolysaccharidoses (MPS), a group of rare genetic disorders caused by defects in glycosaminoglycan (GAG) catabolism, are progressive, multi-systemic diseases with a high burden of morbidity. Enzyme replacement therapy (ERT) is available for MPS I, II, and VI, and may improve walking ability, endurance, and pulmonary function as evidenced by data from pivotal trials and extension studies. Despite these demonstrable benefits, cardiac valve disease, joint disease, and skeletal disease, all of which cause significant morbidity, do not generally improve with ERT if pathological changes are already established. Airway disease improves, but usually does not normalize. These limitations can be well understood by considering the varied functions of GAG in the body. Disruption of GAG catabolism has far-reaching effects due to the triggering of secondary pathogenic cascades. It appears that many of the consequences of these secondary pathogenic events, while they may improve on treatment, cannot be fully corrected even with long-term exposure to enzyme, thereby supporting the treatment of patients with MPS before the onset of clinical disease. This review examines the data from clinical trials and other studies in human patients to explore the limits of ERT as currently used, then discusses the pathophysiology, fetal tissue studies, animal studies, and sibling reports to explore the question of how early to treat an MPS patient with a firm diagnosis. The review is followed by an expert opinion on the rationale for and the benefits of early treatment.

Enzyme replacement therapy for Mucopolysaccharidosis Type I among patients followed within the MPS Brazil Network

Mucopolysaccharidosis type I (MPS I) is a rare lysosomal disorder caused by deficiency of alpha-L-iduronidase. Few clinical trials have assessed the effect of enzyme replacement therapy (ERT) for this condition. We conducted an exploratory, open-label, non-randomized, multicenter cohort study of patients with MPS I. Data were collected from questionnaires completed by attending physicians at the time of diagnosis (T1; n = 34) and at a median time of 2.5 years later (T2; n = 24/34). The 24 patients for whom data were available at T2 were allocated into groups: A, no ERT (9 patients; median age at T1 = 36 months; 6 with severe phenotype); B, on ERT (15 patients; median age at T1 = 33 months; 4 with severe phenotype). For all variables in which there was no between-group difference at baseline, a delta of ≥ ± 20% was considered clinically relevant. The following clinically relevant differences were identified in group B in T2: lower rates of mortality and reported hospitalization for respiratory infection; lower frequency of hepatosplenomegaly; increased reported rates of obstructive sleep apnea syndrome and hearing loss; and stabilization of gibbus deformity. These changes could be due to the effect of ERT or of other therapies which have also been found more frequently in group B. Our findings suggest MPS I patients on ERT also receive a better overall care. ERT may have a positive effect on respiratory morbidity and overall mortality in patients with MPS I. Additional studies focusing on these outcomes and on other therapies should be performed.