| UCOE (Promoter of Ubiquitous HNRPA2B1-CBX3) | Ubiquitous | ++ | 600–2,500 | Antoniou et al., 2013 |
- Promoter 설명 잘 됨: (Kim, 2018 #1218)
| Abbreviation | Size (bp) | Full Name | Strength | Reference |
|---|---|---|---|---|
| CB | 1881 | Flotte patent US 20090186002 | ||
| CBA | 278 | Chicken β-Actin | ||
| CBh | 822 | CMV enhancer-chicken β-actin promoter-hybrid intron (chicken β-actin and minute virus of mice intron) | +++ | Gray, S.J. et al., HUMAN GENE THERAPY 22:1143-1153, 2011 |
| EF1α | 1187 | Human Elongation Factor 1 alpha EF-1α promoter | +++ | Zheng, C. and Baum, B.J., Int. J. Med. Sci., 11(5):404-408, 2014 |
| UBC | 1212 | Human Ubiquitin C gene |
Re-dosing?
[Sarah Jacob]
- I provide a reference with precedence in an animal model: In subjects primed with pre-existing anti-AAV immunity, the transgene product in circulation is affected, but CNS/PNS levels are reasonably maintained in this compartment. https://www.sciencedirect.com/science/article/pii/S1525001616321621
- The approach used in the paper can be applied to this gene therapy program
- We justify re-dosing in cases wherein we measure ~50% drop in the transgene product. Should this be the case, the group will be supported by Global Gene Therapy. Enabling technologies for redosability are under investigation: (1) Vector engineering miRNA binding site to overcome antigen-specific dendritic cell activation (2) Co-administration of AAV with Tolerizing Agent (3) Use of novel engineered capsids that are de-immunized
[Gabi]
For the Parkin PD – our answer should be
We do not consider redosing at this time as it has been shown that transgene expression in neurons is durable, study by Prof. Muramatsu’s team showing efficacy for 15 years in NHP DA neurons https://www.liebertpub.com/doi/abs/10.1089/humc.2017.010
Parkin is an intracellular protein, and will need transgene engineering to make it secreted.
In case that preclinical studies suggests that we need to add re-dosing, then we can add a redosing strategy – with 3 options: : (1) Vector engineering miRNA binding site to overcome antigen-specific dendritic cell activation (2) Co-administration of AAV with Tolerizing Agent (3) Use of novel engineered capsids that are de-immunized – However, such would impact the timeline and delay the time to IND.
Regulatory Element
| Abbreviation | Size (bp) | Full Name | Strength | Reference |
|---|---|---|---|---|
| WPRE | 592 | |||
Route of Administration
| ICM | Intracisternal injection schematic (figure, evidence-only) — sagittal brain cartoon with arrows labelled `Diffusion with the CSF`, `Retrograde transduction`, `Diffusion through the interstitial space`; legend swatches `Strongly transduced area` and `Weakly transduced area`; orange `AAV9 Injection` arrow into the cisterna; small `where injection site` annotation. Citation: Mol Neurobiol (2017) 54:1745–1758, DOI 10.1007/s12035-016-9777-6. | |
| Intra-Parenchymal Delivery |
Good background resource: https://www.youtube.com/playlist?list=PL_3eaar8aMhlsZk5EEq-qikI-JT1AC86K |
Seroepidemiology (Seropositivity)
{Hüser, 2017 #1615} 2nd
- up to 80% of the human population display antibodies against the human AAV serotypes 1 to 3 and AAV5 (9–14).
- Direct comparison of serotype-specific IgGs showed a seroprevalence for AAV1 and AAV2 of around 70%, whereas seroprevalences for AAV5 (40%), AAV6 (46%), AAV8 (38%), and AAV9 (47%) were generally lower (15, 16).
- The development of neutralizing antibodies against AAV1, -2, -5, and -8 followed the same pattern (15, 16).
Potency
| Therapeutic dose | NOAEL | Safety margin | ||
|---|---|---|---|---|
| Voretigene neparvovec | Animal | 1.5×1011 vector genomes/eye | 7.5×1011 vector genomes/eye | X5 |
Safety (Risk)
| Off target | o | Germ line insertion |
▢ 유선자치료제 벡터의 germline 삽입의 위험성을 제시하여 생체분포(bio-distribution) ▢ ICH 의 'Consideration on General Principles to Address the Risk of Inadvertent Germline Integration of Gene Therapy Vectors (2006)' 에 ▢ 시험의 필요성을 강조하였으며 특히, 생식장기(고환, 난소)에서의 벡터의 분포를 RT-PCR 과 같은 민감도가 좋은 정량분석 기법을 추천하고 있다 | |
|---|---|---|---|---|
| prolonged biological activity after a single administration | ||||
| Cancerogenesis | ||||
| Viral Shedding |
excretion/secretion of viral particles or bacteria that could be transmitted to other individuals, may be observed as a result of biodistribution2 the release of virus-based gene therapy products [SEP] from the patient through one or all of the following routes: [SEP] excreta (feces), secreta (urine, saliva, nasopharyngeal fluids, etc.), and skin (pustule, sores, wounds) | |||
| Immunogenicity expression of a delivered gene may be uncontrolled and interfere with normal function of a critical enzyme | ||||
| systemic expression | ||||
DRG Toxicity
- Tox studies: potential impact on number of species used. Limitations of NHPs suggest need for different model
- No overall consensus of types of studies to be performed both pre-clinical and in the clinic, but suggest >1 animal model
Neurotoxicity (Brain MRI)
- Attributed primarily to IP ROA; potential that future studies need to have strong justification to use this ROA
- Potential increased expectations of regular neuroimaging (e.g 3, 6, 12 months, yearly)
Concerns of dorsal root ganglion pathology in terms of routes of administration and AAV serotypes
(Slide block, Takeda branding visible — transcribed text, slide image not embedded)
- Dorsal root ganglion (DRG) pathology is almost universal after AAV gene administration in non-human primate.
- The severity of the DRG pathology was dose-dependent. This means possible NOAEL can be obtained.
- Administration route of AAV via ICM/intra CSF, IV and IM indicated high, middle and no incidence of DRG pathology, respectively.
- There is no obvious difference in DRG pathology among AAV1, AAV5 and AAV9.
- In the Takeda’s experience in the preliminary 3-month monkey study of TAK-686, which uses AAV9 vector, degeneration on DRG was observed in the intracerebroventricular (ICV, 1.14×10^12 vg/animal) group and not observed in the intraputamental (Ipa, 3.48×10^12 vg/animal) group.
See here for more details: HUMAN GENE THERAPY VOLUME 32, NUMBERS 15 and 16 (2021); TAK-686 Pre-IND Briefing Document (October 17, 2019).
FDA CTGT Advisory Committee Meeting – 02Sept2021 — Key Takeaways
(Slide block — transcribed text, slide image not embedded)
- AAV Vector Integration & Oncogenicity
- While considered very low risk, risk factors vary by disease
- Must consider as AAV doses increase (esp IV RoA) and underlying liver conditions
- No recommendation to significantly change current clinical monitoring (liver enzymes, ultrasounds, etc)
- AAV Hepatotoxicity
- Similar to above that risk increases with dose and underlying conditions
- Potential upper limit of dosing, although difficult to compare doses across studies
- Thrombotic Microangiopathy (TMA)
- Generally considered to be capsid driven and associated with rising levels of anti-capsid IgM antibodies
- Potential implications on tox studies for new capsids
- Potential agency will refine expectations on CMC quality (empty & partial capsids, encapsidated DNA impurities, etc)
- Generally considered to be capsid driven and associated with rising levels of anti-capsid IgM antibodies
Gene therapy specific safety considerations
(Slide table — transcribed text, slide image not embedded)
| Potential safety issue | Underlying mechanism | Clinical monitoring | Mitigation/management |
|---|---|---|---|
| Thrombotic microangiopathy | Innate immune response | Frequent clinical and lab monitoring during 2 weeks after gene therapy: check for fever, vomiting, hypertension, decreased urine output, presence of thrombocytopenia, hemolytic anemia, proteinuria, increase in LDH, changes in the complement panel, or increase in serum creatinine |
• Early clinical event • Risk with IV RoA >> ICM/IT RoA • Early recognition is key to ensure the optimal clinical outcome (no preventive measures exist) • Need to train investigators on TMA sign/symptoms and ensure urgent access to nephrologist if needed. • Management may include supportive treatment and/or eculizumab • Exclude patient with recent infection (may increase TMA risk) |
| Hepatotoxicity | Adaptive immune response | Liver enzyme monitoring |
• Risk with IV RoA >> ICM/IT RoA • Preventive IS regimen suppressing T-cell activation • Rescue steroids • Exclude patients with frail liver and recent Hb infections |
| DRG Toxicity | Transgene overexpression in DRGs |
• Monitoring for potentially emerging sensory abnormalities • Monitoring of inflammatory response in the CSF • Symptom-driven spine MRI • Symptom-driven EMG/NCS |
• Risk with ICM/IT RoA >> IV RoA • No real preventive measure; IS/steroids may help alleviate downstream inflammatory/immune response • Exclude patients with pre-existing sensory neuropathies |
Uncertain Spans
| location | transcription | uncertainty |
|---|---|---|
| Safety table, Germ line insertion bullet | ▢ placeholder rendered for the original Korean bullet glyph | The source uses a small empty box-with-question-mark glyph as bullet marker; rendered as ▢ because the exact code point is not crisp. |
| Viral Shedding cell | [SEP] literal token | Two small superscript SEP-style icons appear inline in the source slide; transcribed as [SEP] placeholders; the original glyph is a tiny dotted-line icon and not a Unicode character. |
| Hepatotoxicity slide row, Mitigation column, last bullet | frail liver and recent Hb infections | The token Hb in the slide is small and partially highlighted; could plausibly read HBV (hepatitis B virus) but the visible glyph is two characters Hb. |
| Concerns of DRG slide footer | HUMAN GENE THERAPY VOLUME 32, NUMBERS 15 and 16 (2021) | The source line shows (2021)/HUMAN GENE THERAPY references at small size; volume 32 vs 31 and the trailing date are not perfectly legible — recorded as the most likely reading. |
| TAK-686 footer | October 17, 2019 for the Pre-IND Briefing Document date | Date is small print; transcribed as best interpretation. |