Immune response to enzyme replacement therapies in lysosomal storage diseases and the role of immune tolerance induction

The US Food and Drug Administration (FDA) and National Organization for Rare Disease (NORD) convened a public workshop titled "Immune Responses to Enzyme Replacement Therapies: Role of Immune Tolerance Induction" to discuss the impact of anti-drug antibodies (ADAs) on efficacy and safety of enzyme replacement therapies (ERTs) intended to treat patients with lysosomal storage diseases (LSDs). Participants in the workshop included FDA staff, clinicians, scientists, patients, industry, and advocacy group representatives. The risks and benefits of implementing prophylactic immune tolerance induction (ITI) to reduce the potential clinical impact of antibody development were considered. Complications due to immune responses to ERT are being recognized with increasing experience and lengths of exposure to ERTs to treat several LSDs. Strategies to mitigate immune responses and to optimize therapies are needed. Discussions during the workshop resulted in the identification of knowledge gaps and future areas of research, as well as the following proposals from the participants: (1) systematic collection of longitudinal data on immunogenicity to better understand the impact of ADAs on long-term clinical outcomes; (2) development of disease-specific biomarkers and outcome measures to assess the effect of ADAs and ITI on efficacy and safety; (3) development of consistent approaches to ADA assays to allow comparisons of immunogenicity data across different products and disease groups, and to expedite reporting of results; (4) establishment of a system to widely share data on antibody titers following treatment with ERTs; (5) identification of components of the protein that are immunogenic so that triggers and components of the immune responses can be targeted in ITI; and (6) consideration of early ITI in patients who are at risk of developing clinically relevant ADA that have been demonstrated to worsen treatment outcomes.

A myostatin and activin decoy receptor enhances bone formation in mice

Myostatin is a member of the bone morphogenetic protein/transforming growth factor-β (BMP/TGFβ) super-family of secreted differentiation factors. Myostatin is a negative regulator of muscle mass as shown by increased muscle mass in myostatin deficient mice. Interestingly, these mice also exhibit increased bone mass suggesting that myostatin may also play a role in regulating bone mass. To investigate the role of myostatin in bone, young adult mice were administered with either a myostatin neutralizing antibody (Mstn-mAb), a soluble myostatin decoy receptor (ActRIIB-Fc) or vehicle. While both myostatin inhibitors increased muscle mass, only ActRIIB-Fc increased bone mass. Bone volume fraction (BV/TV), as determined by microCT, was increased by 132% and 27% in the distal femur and lumbar vertebrae, respectively. Histological evaluation demonstrated that increased BV/TV in both locations was attributed to increased trabecular thickness, trabecular number and bone formation rate. Increased BV/TV resulted in enhanced vertebral maximum compressive force compared to untreated animals. The fact that ActRIIB-Fc, but not Mstn-mAb, increased bone volume suggested that this soluble decoy receptor may be binding a ligand other than myostatin, that plays a role in regulating bone mass. This was confirmed by the significant increase in BV/TV in myostatin deficient mice treated with ActRIIB-Fc. Of the other known ActRIIB-Fc ligands, BMP3 has been identified as a negative regulator of bone mass. However, BMP3 deficient mice treated with ActRIIB-Fc showed similar increases in BV/TV as wild type (WT) littermates treated with ActRIIB-Fc. This result suggests that BMP3 neutralization is not the mechanism responsible for increased bone mass. The results of this study demonstrate that ActRIIB-Fc increases both muscle and bone mass in mice. Therefore, a therapeutic that has this dual activity represents a potential approach for the treatment of frailty.

Custom made alar stents for nostril stenosis: a 24-month evaluation

Nostril stenosis is an uncommon deformity and its aetiology is variable. The shape alteration and nostril asymmetry may have negative aesthetic and functional effects on nostril stenosis patients. Five patients were included in this study and followed up for 24 months; four of these had congenital nostril stenosis and one had an acquired deformity. Alar stent dilators were constructed from measured diameter of the affected nostril/s. The congenital nostril stenosis patients initially received a customised chairside soft nasal dilator (CCSND), which were later replaced with a customised laboratory rigid nasal dilators (CLRND). Treatment outcomes were evaluated using a questionnaire and a visual analogue scale to assess improvements in nostril breathing, comfort, appearance and satisfaction of the treatment provided by both types of dilators. There was improvement in nostril diameter with an average expansion of 7mm and this was stable at the desired diameter. The overall number of stents used to expand the tissues to the desired dimension ranged from 3 to 8 stents. Alar stent therapy is a conservative method to expand nostril tissues and has successfully maintained the nostril diameter for both acquired and congenital stenosis. This improvement in all parameters and the patients' satisfaction would make the custom-made nostril dilator in particular the CLRND a satisfactory treatment modality for congenital and acquired nostril stenosis.

Cervical intraepithelial neoplasia in female prisoners in British Columbia

The annual incidence rates of cervical intraepithelial neoplasia (CIN), grades I to III, from 1975 to 1983 among 2440 prisoners in British Columbia for whom a history of screening by means of the Papanicolaou test was available were two to three times higher than the expected rates in the general female population of British Columbia. The rates among the prisoners from 1970 to 1984, although small, increased with a trend similar to that in the general population. Despite increases in the general population we conclude that prisoners are still at high risk for CIN.