Adeno-associated virus serotype 9 antibodies in patients screened for treatment with onasemnogene abeparvovec.

Spinal muscular atrophy is a progressive, recessively inherited monogenic neurologic disease, the genetic root cause of which is the absence of a functional survival motor neuron 1 gene. Onasemnogene abeparvovec (formerly AVXS-101) is an adeno-associated virus serotype 9 vector-based gene therapy that delivers a fully functional copy of the human survival motor neuron gene. We report anti-adeno-associated virus serotype 9 antibody titers for patients with spinal muscular atrophy when they were screened for eligibility in the onasemnogene abeparvovec clinical trials (intravenous and intrathecal administration) and managed access programs (intravenous). Through December 31, 2019, 196 patients and 155 biologic mothers were screened for anti-adeno-associated virus serotype 9 binding antibodies with an enzyme-linked immunosorbent assay. Of these, 15 patients (7.7%) and 23 biologic mothers (14.8%) had titers >1:50 on their initial screening tests. Eleven patients (5.6%) had elevated titers on their final screening tests. The low percentage of patients with exclusionary antibody titers indicates that most infants with spinal muscular atrophy type 1 should be able to receive onasemnogene abeparvovec. Retesting may identify patients whose antibody titers later decrease to below the threshold for treatment, and retesting should be considered for patients with anti-adeno-associated virus serotype 9 antibody titers >1:50.

AVXS-101 (Onasemnogene Abeparvovec) for SMA1: Comparative Study with a Prospective Natural History Cohort.

BACKGROUND: Spinal muscular atrophy type 1 (SMA1) is the leading genetic cause of infant mortality for which therapies, including AVXS-101 (onasemnogene abeparvovec, Zolgensma®) gene replacement therapy, are emerging. OBJECTIVE: This study evaluated the effectiveness of AVXS-101 in infants with spinal muscular atrophy type 1 (SMA1) compared with a prospective natural history cohort and a cohort of healthy infants. METHODS: Twelve SMA1 infants received the proposed therapeutic dose of AVXS-101 (NCT02122952). Where possible, the following outcomes were compared with a natural history cohort of SMA1 infants (n = 16) and healthy infants (n = 27) enrolled in the NeuroNEXT (NN101) study (NCT01736553): event-free survival, CHOP-INTEND scores, motor milestone achievements, compound muscle action potential (CMAP), and adverse events. RESULTS: Baseline characteristics of SMA1 infants in the AVXS-101 and NN101 studies were similar in age and genetic profile. The proportion of AVXS-101-treated infants who survived by 24 months of follow-up was higher compared with the NN101 study (100% vs 38%, respectively). The average baseline CHOP-INTEND score for NN101 SMA1 infants was 20.3, worsening to 5.3 by age 24 months; the average baseline score in AVXS-101-treated infants was 28.2, improving to 56.5 by age 24 months. Infants receiving AVXS-101 achieved motor milestones, such as sitting unassisted and walking. Improvements in CMAP peak area were observed in AVXS-101-treated infants at 6 and 24 months (means of 1.1 and 3.2 mV/s, respectively). CONCLUSIONS: In this study, AVXS-101 increased the probability of survival, rapidly improved motor function, and enabled motor milestone achievement in SMA1 infants.

Impact of Age and Motor Function in a Phase 1/2A Study of Infants With SMA Type 1 Receiving Single-Dose Gene Replacement Therapy.

BACKGROUND: This study characterizes motor function responses after early dosing of AVXS-101 (onasemnogene abeparvovec) in gene replacement therapy in infants with severe spinal muscular atrophy type 1 (SMA1). METHODS: This study is a follow-up analysis of 12 infants with SMA1 who received the proposed therapeutic dose of AVXS-101 in a Phase 1 open-label study (NCT02122952). Infants were grouped according to age at dosing and baseline Children's Hospital of Philadelphia Infant Test of Neuromuscular Disorders scores: (1) early dosing/low motor, dosed age less than three months with scores <20 (n = 3), (2) late dosing, dosed at age three months or greater (n = 6), and (3) early dosing/high motor, dosed age less than three months with scores ≥20 (n = 3). RESULTS: Early dosing/low motor group demonstrated a mean gain of 35.0 points from a mean baseline of 15.7, whereas the late dosing group had a mean gain of 23.3 from a mean baseline of 26.5. The early dosing/high motor group quickly reached a mean score of 60.3, near the scale maximum (64), from a mean baseline of 44.0. Despite a lower baseline motor score, the early dosing/low motor group achieved sitting unassisted earlier than the late dosing group (mean age: 17.0 vs 22.0 months). The early dosing/high motor group reached this milestone earliest (mean age: 9.4 months). CONCLUSIONS: The rapid, significant motor improvements among infants with severe SMA1 treated with AVXS-101 at an early age highlight the importance of newborn screening and early treatment and demonstrate the therapeutic potential of AVXS-101 regardless of baseline motor function.

High Healthcare Resource Use in Hospitalized Patients with a Diagnosis of Spinal Muscular Atrophy Type 1 (SMA1): Retrospective Analysis of the Kids' Inpatient Database (KID).

BACKGROUND: Patients with spinal muscular atrophy (SMA) have high healthcare resource use (HRU) due to respiratory and nutritional complications resulting from progressive muscle atrophy. While previous studies estimate the direct costs to be US$113,000 to US$121,682 per year in the US, they potentially understate costs for type 1 SMA (SMA1). This study analyzed HRU in hospitalizations with a diagnosis of SMA1 and compared it with hospitalizations with complex chronic conditions (CCC) other than SMA1 or those with no CCC. METHODS: This retrospective analysis of a defined subset of the 2012 Kids' Inpatient Database (KID) compared a nationally estimated number of hospitalizations of children (aged < 3 years) categorized into three groups: (1) SMA1 (n = 237 admissions), (2) no CCC (n = 632,467 admissions), and (3) other CCC (n = 224,953 admissions). RESULTS: Mean total charges were higher for SMA1 admissions compared with admissions with no CCC (US$150,921 vs US$19,261 per admission, respectively; costs: US$50,190 vs $5862 per admission, respectively; both p < 0.0001). A larger proportion of SMA1 admissions were billed for one or more procedure codes (81.9%) than in the no CCC group (39.4%) or other CCC group (70.1%; both p ≤ 0.0003). SMA1 admissions had a longer length of stay compared with admissions with no CCC (15.1 vs 3.4, respectively; p < 0.0001). CONCLUSIONS: The average total charges for a single SMA1 admission were higher than those of the no CCC group. Because most infants with SMA1 require multiple hospitalizations per year, previous estimates may dramatically underestimate the direct costs associated with HRU. Further studies are required to determine the indirect costs and societal impacts of SMA1.

A convex urostomy pouch with adhesive border: a patient survey.

Patients previously using a standard-wear convex skin barrier urostomy pouch were invited by letter from a Dispensing Appliance Contractor to evaluate a similar pouching system, but with the addition of an extended-wear convex barrier and adhesive border. A total of 47 patients agreed to take part. Patients were asked to try three pouches and complete one evaluation form. Study participants found the addition of an extended-wear convex barrier and adhesive border, was easy to use, provided them with security and the potential for longer wear time.