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Braun M, Lange C, Schatz P, Long B, Stanta J, Gorovits B, Tarcsa E, Jawa V, Yang TY, Lembke W, Miller N, McBlane F, Christodoulou L, Yuill D, Milton M. Preexisting antibody assays for gene therapy: Considerations on patient selection cutoffs and companion diagnostic requirements. Mol Ther Methods Clin Dev 2024; 32:101217. [PMID: 38496304 PMCID: PMC10944107 DOI: 10.1016/j.omtm.2024.101217] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/19/2024]
Abstract
Recombinant adeno-associated virus (AAV) vectors are the leading delivery vehicle used for in vivo gene therapies. Anti-AAV antibodies (AAV Abs) can interact with the viral capsid component of an AAV-based gene therapy (GT). Therefore, patients with preexisting AAV Abs (seropositive patients) are often excluded from GT trials to prevent treatment of patients who are unlikely to benefit1 or may have a higher risk for adverse events outweighing treatment benefits. On the contrary, unnecessary exclusion of patients with high unmet medical need should be avoided. Instead, a risk-benefit assessment that weighs the potential risks due to seropositivity vs. severity of disease and available treatment options, should drive the decision if patient selection is required. Assays for patient selection must be validated according to their intended use following national regulations/standards for diagnostic assays in appropriate laboratories. In this review, we summarize the current process of patient selection, including assay cutoff criteria and related assay validation approaches. We further provide considerations on regulatory requirements for the development of in vitro diagnostic tests supporting market authorization of a corresponding GT.
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Affiliation(s)
- Manuela Braun
- Bayer AG, Pharmaceuticals R&D, 13342 Berlin, Germany
| | - Claudia Lange
- Bayer AG, Pharmaceuticals R&D, 13342 Berlin, Germany
| | | | - Brian Long
- BioMarin Pharmaceutical Inc, Novato, CA, USA
| | | | - Boris Gorovits
- Sana Biotechnology, 100 Technology Square, Cambridge, MA 02139, USA
| | - Edit Tarcsa
- Abbvie Bioresearch Center, Worcester, MA 01605, USA
| | - Vibha Jawa
- Bristol Myers Squibb, Lawrence Township, NJ 08648, USA
| | | | - Wibke Lembke
- Integrated Biologix GmbH, 4051 Basel, Switzerland
| | - Nicole Miller
- Ultragenyx Pharmaceutical Inc, Novato, CA 94949, USA
| | | | | | - Daisy Yuill
- AstraZeneca, 1 Francis Crick Avenue, CB2 0AA Cambridge, UK
| | - Mark Milton
- Lake Boon Pharmaceutical Consulting, LLC, Hudson, MA 01749, USA
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Dosi C, Masson R. The impact of three SMN2 gene copies on clinical characteristics and effect of disease-modifying treatment in patients with spinal muscular atrophy: a systematic literature review. Front Neurol 2024; 15:1308296. [PMID: 38487326 PMCID: PMC10937544 DOI: 10.3389/fneur.2024.1308296] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2023] [Accepted: 02/12/2024] [Indexed: 03/17/2024] Open
Abstract
Objective To review the clinical characteristics and effect of treatment in patients with spinal muscular atrophy (SMA) and three copies of the SMN2 gene. Methods We conducted a literature search in October 2022 to identify English-language clinical research on SMA that included SMN2 copy number according to PRISMA guidelines. Results Our search identified 44 studies examining the impact of three SMN2 copies on clinical characteristics (21 on phenotype, 13 on natural history, and 15 on functional status and other signs/symptoms). In children with type I SMA or presymptomatic infants with an SMN1 deletion, three SMN2 copies was associated with later symptom onset, slower decline in motor function and longer survival compared with two SMN2 copies. In patients with SMA type II or III, three SMN2 copies is associated with earlier symptom onset, loss of ambulation, and ventilator dependence compared with four SMN2 copies. Eleven studies examined treatment effects with nusinersen (nine studies), onasemnogene abeparvovec (one study), and a range of treatments (one study) in patients with three SMN2 copies. In presymptomatic infants, early treatment delayed the onset of symptoms and maintained motor function in those with three SMN2 copies. The impact of copy number on treatment response in symptomatic patients is still unclear. Conclusion SMN2 copy number is strongly correlated with SMA phenotype in patients with SMN1 deletion, while no correlation was found in patients with an SMN1 mutation. Patients with three SMN2 copies show a highly variable clinical phenotype. Early initiation of treatment is highly effective in presymptomatic patients with three SMN2 copies.
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Affiliation(s)
| | - Riccardo Masson
- Fondazione IRCCS Istituto Neurologico Carlo Besta, Developmental Neurology Unit, Milan, Italy
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Wei C, Li D, Zhang M, Zhao Y, Liu Y, Fan Y, Wang L, Liu J, Chang X, Jiang Y, Xiong H. Prevalence of Adeno-Associated Virus-9-Neutralizing Antibody in Chinese Patients with Duchenne Muscular Dystrophy. Hum Gene Ther 2024; 35:26-35. [PMID: 38084965 DOI: 10.1089/hum.2023.117] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2023] Open
Abstract
The delivery of a mini-dystrophin gene to skeletal muscles using recombinant adeno-associated virus serotype (AAV) holds great potential as a gene therapy for Duchenne muscular dystrophy (DMD). However, the presence of anti-AAV-neutralizing antibodies (NAbs) may impede the effectiveness of gene transduction. This study aimed to evaluate the prevalence of anti-AAV9 NAbs in Chinese patients with DMD, and to characterize the target population for an AAV gene therapy. A total of one hundred male patients with DMD were included in this study, and demographic and clinical data were collected. A blood specimen was obtained from each participant for the purpose of evaluating the existence of anti-AAV9 NAbs through a cell-based functional assay conducted at a central laboratory. A NAb titer exceeding 1:4 was considered positive. The positivity rates of anti-AAV9 NAb were compared among different subgroups. The median age of this DMD cohort was 8 years old, ranging from 3 to 15 years of age. Forty-two percent of patients tested positive for anti-AAV9 NAb. Notably, all samples from patients under 4 years of age tested negative, and the positivity rates of anti-AAV9 NAb differed significantly across the three age subgroups (<4 years old, ≥4 years old and <12 years old, and ≥12 years old, χ2 = 7.221, p = 0.023). Further investigation into the living environment revealed a higher positivity rate of anti-AAV9 NAb in rural patients compared with urban patients (χ2 = 3.923, p = 0.048). Moreover, the prevalence in patients from different cities/provinces varied greatly (χ2 = 16.550, p = 0.003). There was no statistically significant difference in the positivity rate of NAb among subgroups of patients with different motor functions (ambulatory or nonambulatory) and different treatment strategies (taking or not taking glucocorticoid). In Chinese DMD patients, the prevalence of anti-AAV9 NAb was found to reach 42%. Moreover, the antibody-positive rate in children <4 years of age was low and revealed notable regional discrepancies.
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Affiliation(s)
- Cuijie Wei
- Department of Pediatrics, Peking University First Hospital, Beijing, P.R. China
| | - Dongliang Li
- Department of Pediatrics, Peking University First Hospital, Beijing, P.R. China
| | - Meng Zhang
- Department of Pediatrics, Peking University First Hospital, Beijing, P.R. China
| | - Yanping Zhao
- Department of Pediatrics, Peking University First Hospital, Beijing, P.R. China
| | - Yidan Liu
- Department of Pediatrics, Peking University First Hospital, Beijing, P.R. China
| | - Yanbin Fan
- Department of Pediatrics, Peking University First Hospital, Beijing, P.R. China
| | - Lu Wang
- Department of Pediatrics, Peking University First Hospital, Beijing, P.R. China
| | - Jieyu Liu
- Department of Pediatrics, Peking University First Hospital, Beijing, P.R. China
| | - Xingzhi Chang
- Department of Pediatrics, Peking University First Hospital, Beijing, P.R. China
| | - Yuwu Jiang
- Department of Pediatrics, Peking University First Hospital, Beijing, P.R. China
| | - Hui Xiong
- Department of Pediatrics, Peking University First Hospital, Beijing, P.R. China
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Day JW, Mendell JR, Burghes AH, van Olden RW, Adhikary RR, Dilly KW. Adeno-associated virus serotype 9 antibody seroprevalence for patients in the United States with spinal muscular atrophy. Mol Ther Methods Clin Dev 2023; 31:101117. [PMID: 37822718 PMCID: PMC10562739 DOI: 10.1016/j.omtm.2023.101117] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Accepted: 09/14/2023] [Indexed: 10/13/2023]
Abstract
Onasemnogene abeparvovec is a recombinant adeno-associated virus serotype 9 (AAV9) vector-based gene therapy for spinal muscular atrophy (SMA). Patients with elevated titers of anti-AAV9 antibodies (AAV9-Ab) should not receive onasemnogene abeparvovec because of potential safety and efficacy implications. We conducted a retrospective study to describe the seroprevalence of anti-AAV9 binding antibodies for pediatric patients with SMA in the United States. At initial testing, 13.0% (115 of 882) of patients (mean [SD] age, 26.29 [33.66] weeks) had elevated AAV9-Ab titers. The prevalence of elevated titers decreased as age increased, with 18.2% (92 of 507) of patients ≤3 months old but only 1.1% (1 of 92) of patients ≥21 months old having elevated titers. This suggests transplacental maternal transfer of antibodies. No patterns of geographic variations in AAV9-Ab prevalence were confirmed. Elevated AAV9-Ab titers in children <6 weeks old decreased in all circumstances. Lower magnitudes of elevated titers declined more rapidly than greater magnitudes. Retesting was completed at the discretion of the treating clinician, so age at testing and time between tests varied. AAV9-Ab retesting should be considered when patients have elevated titers, and elevations at a young age are not a deterrent to eventual onasemnogene abeparvovec administration. Early disease-modifying treatment for SMA leads to optimal outcomes.
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Affiliation(s)
- John W. Day
- Department of Neurology, Stanford University Medical Center, Stanford, CA, USA
| | - Jerry R. Mendell
- Center for Gene Therapy, Nationwide Children’s Hospital, Columbus, OH, USA
- Department of Pediatrics and Department of Neurology, The Ohio State University, Columbus, OH, USA
| | - Arthur H.M. Burghes
- Department of Neurology and Department of Biological Chemistry and Pharmacology, The Ohio State University, Columbus, OH, USA
| | | | - Rishi R. Adhikary
- CONEXTS-Real World Evidence, Novartis Healthcare Private Limited, Hyderabad, India
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