Immunomodulation in Administration of rAAV: Preclinical and Clinical Adjuvant Pharmacotherapies.

Recombinant adeno-associated virus (rAAV) has attracted a significant research focus for delivering genetic therapies to target cells. This non-enveloped virus has been trialed in many clinical-stage therapeutic strategies but important obstacle in clinical translation is the activation of both innate and adaptive immune response to the protein capsid, vector genome and transgene product. In addition, the normal population has pre-existing neutralizing antibodies against wild-type AAV, and cross-reactivity is observed between different rAAV serotypes. While extent of response can be influenced by dosing, administration route and target organ(s), these pose concerns over reduction or complete loss of efficacy, options for re-administration, and other unwanted immunological sequalae such as local tissue damage. To reduce said immunological risks, patients are excluded if they harbor anti-AAV antibodies or have received gene therapy previously. Studies have incorporated immunomodulating or suppressive regimens to block cellular and humoral immune responses such as systemic corticosteroids pre- and post-administration of Luxturna® and Zolgensma®, the two rAAV products with licensed regulatory approval in Europe and the United States. In this review, we will introduce the current pharmacological strategies to immunosuppress or immunomodulate the host immune response to rAAV gene therapy.

Treatable childhood neuronopathy caused by mutations in riboflavin transporter RFVT2.

Childhood onset motor neuron diseases or neuronopathies are a clinically heterogeneous group of disorders. A particularly severe subgroup first described in 1894, and subsequently called Brown-Vialetto-Van Laere syndrome, is characterized by progressive pontobulbar palsy, sensorineural hearing loss and respiratory insufficiency. There has been no treatment for this progressive neurodegenerative disorder, which leads to respiratory failure and usually death during childhood. We recently reported the identification of SLC52A2, encoding riboflavin transporter RFVT2, as a new causative gene for Brown-Vialetto-Van Laere syndrome. We used both exome and Sanger sequencing to identify SLC52A2 mutations in patients presenting with cranial neuropathies and sensorimotor neuropathy with or without respiratory insufficiency. We undertook clinical, neurophysiological and biochemical characterization of patients with mutations in SLC52A2, functionally analysed the most prevalent mutations and initiated a regimen of high-dose oral riboflavin. We identified 18 patients from 13 families with compound heterozygous or homozygous mutations in SLC52A2. Affected individuals share a core phenotype of rapidly progressive axonal sensorimotor neuropathy (manifesting with sensory ataxia, severe weakness of the upper limbs and axial muscles with distinctly preserved strength of the lower limbs), hearing loss, optic atrophy and respiratory insufficiency. We demonstrate that SLC52A2 mutations cause reduced riboflavin uptake and reduced riboflavin transporter protein expression, and we report the response to high-dose oral riboflavin therapy in patients with SLC52A2 mutations, including significant and sustained clinical and biochemical improvements in two patients and preliminary clinical response data in 13 patients with associated biochemical improvements in 10 patients. The clinical and biochemical responses of this SLC52A2-specific cohort suggest that riboflavin supplementation can ameliorate the progression of this neurodegenerative condition, particularly when initiated soon after the onset of symptoms.

Laparoscopic antegrade continence enema using a two-port technique.

BACKGROUND: The antegrade continence enema is an effective method of treatment of fecal incontinence. We report our experience of a laparoscopic antegrade continence enema procedure and describe a simple approach to this procedure using a two-port technique. MATERIALS AND METHODS: Over a 3-year period, 12 children with intractable constipation and fecal soiling underwent the antegrade continence enema procedure laparoscopically. All cases had full bowel preparation the day before surgery. This procedure was done through one 5-mm camera port and two 5-mm working ports in 8 cases, and using the camera port and only one additional 5-mm working port in 4 cases. The appendix was used in 5 cases and the cecum in 3 cases with the threeport technique while the appendix was used in all 4 cases with the two-port technique. The appendix or cecum was delivered extracorporeally through the 5-mm port site in the right lower quadrant. The mucocutaneous anastomosis was stented using a gastrostomy button. RESULTS: Between 2001 and 2004, 12 children (10 male, 2 female) underwent a laparoscopic antegrade continence enema procedure at a median age of 10.5 years (range, 7-14 years). This procedure was easy to perform and no case required conversion to an open procedure. The wash-outs via the MIC-KEY gastrostomy button (MIC-KEY, Kimberly-Clark) were commenced at a median of 3.5 days (range, 1-5 days). Median postoperative hospital stay was 2 days (range, 1-5 days). This procedure was effective in completely resolving fecal incontinence in 9 cases and partially resolving it in 3 cases. There were no episodes of stomal stenosis, leakage, or herniation. However, one case required a revision of antegrade continence enema due to wound breakdown and leakage of irrigation fluid around the stoma. The median follow-up period was 15.5 months (range, 5-32 months). CONCLUSION: The laparoscopic technique is a simple and effective approach in creating an antegrade continence enema. The use of a gastrostomy button can potentially reduce some of the complications commonly associated with an antegrade continence enema. We describe a procedure that incorporates the advantages of both laparoscopy and a button device, which is simple and easy to perform using just two ports.