Introduction Gene therapy is a medical intervention based on the modification of the genetic material of living cells. Currently, gene
therapy is restricted in application to somatic cells.
Based on transferring methods, gene therapy can be classified into two categories: ex vivo and in vivo. ex vivo gene therapy refers to cells being modified ex vivo for subsequent administration to humans, while in vivo refers to cells being altered in vivo by giving gene therapy directly to the subject. The products of ex vivo gene therapy are cells that are modified and are intended to be administered to the patient. ex vivo gene therapy is expected to be performed in well-established medical care establish- ments with specially trained medical
professionals and GMP facilities. The products of in vivo gene therapy are recombinant DNA or RNA in the form of naked DNA, DNA complex, or viral vectors that are manipulated by genetic
technologies. Both ex vivo and in vivo gene therapy products are subject to the regulations in this guidance. Because of the complexities of the different modalities
of gene therapy, it is not possible to generalize a common guidance that is suitable for all kinds of products. However, the
following basic principles should be followed when sponsoring the development of a gene therapy product:
1 The safety and efficacy of the product should be guaranteed. A comprehensive assessment of the benefit and risk of the product
should be conducted.
2 New and innovative ideas should be promoted when sponsoring gene therapy product development. Considering the uniqueness of
gene therapy relative to traditional chemically synthesized and genetically engineered protein medicines, there will be certain
flexibilities for the regulation of novel gene therapy products. Gene therapy as a form of medical intervention is still in
its early phase of development. SFDA expects the sponsors to not just follow this guidance but also to conduct rigorous scientific
study to ensure the development of a safe and efficacious gene therapy product.
When applying to conduct a clinical trial of an investigational new gene therapy drug (IND) from the State Food and Drug Administration
(SFDA), the sponsor should prepare the application following the guidance in this document. In addition, the following information
should be provided:
1 Review of the research and development of the relevant gene therapy field
The review should cover the following topics:
- therapeutic gene
- delivery vehicle
- gene delivery system and method
- in vivo study efficacy data
- preclinical animal study, including toxicity, safety, and efficacy data
- clinical trial investigation plan, including safety and efficacy study
- overview of production process
- overview of quality control
- discussion of the novelty of the product
- discussion of the product commer-cialization strategy.
The review should be comprehensive and up to date.
2 Review of the intellectual property status of the product
The review should cover the following topics:
2.1 Overview of the intellectual property status of the proposed product
2.2 Reference and patent search report
The reference and patent search should cover the therapeutic gene, delivery vehicle, delivery product, and other components
in the final product, producer cell and production process, and related topics.
Application Content and Product Quality Control
The following should be included in the application proposal:
1. Construction of the DNA expression cassette and the gene delivery system1.1 Therapeutic target gene
A detailed description of the clonal origin of the therapeutic target gene, including a patent search on the gene, should
be provided. Method of gene cloning and sequence identity should be provided.
1.2 Vector
Information supplied should include restriction mapping and gene-bank data for the vector. Known regulatory elements such
as promoters, enhancers, and PolyA should be identified. If there is any change in the vector backbone gene structure (such
as deletion, mutation, or insertion), the DNA sequence data should be provided. For a new viral vector, it is necessary to
provide information on the material, method of construction, and testing of the new vector.
For non-viral gene delivery systems, plasmid is needed to express the target gene in human cells. In addition to naked DNA,
another component is generally used to complex with the DNA. This guidance does not cover oligoribo-nucleotide (such as antisense
RNA, ribozyme, and siRNA) products.
1.3 DNA expression cassette
A detailed description of the cloning procedure, the methods and materials used, and DNA sequence data should be given. Known
regulatory elements such as promoters, enhancers, and PolyA should be identified. Restriction mapping of the gene expression
cassette and the kinetics of gene expression should be provided.
1.4 Construction of the gene delivery system (including viral and non-viral gene delivery systems)
1.4.1 Viral gene delivery system including adenoviral vector, retroviral vector, and adeno-associated viral (AAV) vector
A thorough description of the clonal origin of the viral vector should be provided. The methods and materials used for the
construction of the viral vector should be included. Testing methods and results should also be provided. General testing
should include structural analysis (for example, restriction mapping and PCR), complete sequencing of the viral genome (≤
40kb), gene expression and bioactivity analysis, SDS-PAGE (sodium dodecyl sulfate-polyacrylamide gel electrophoresis), DNA
sequencing of the gene expression cassette, Western blot analysis of the expressed protein, transduction efficiency analysis,
negative-staining transmission electron-microscopy of the purified viral vector, replication-competent virus detection, and
analysis for residual process contaminants.
1.4.2 Non-viral gene delivery system
Non-viral gene delivery systems encompass naked DNA, mammalian cell carrier systems, and other carrier systems such as liposome,
polypeptide, and gold particles. The nature and characteristics of the non-viral delivery system should be described adequately.
To prevent allergic reaction to penicillin in some patient populations, it is recommended that a kanamycin- or neomycin-resistant
gene be used as the drug selection gene.
For the physical delivery system, a detailed description of the delivery method, procedure, efficiency of gene delivery and
expression, gene stability after delivery, and bioactivity should be included. Evidence of absence of gene arrangement and
mutation should be provided. Detailed testing results should be given, including plasmid restriction mapping, PCR analysis,
DNA sequencing of the gene expression cassette, SDS-PAGE, and Western blot analysis of the expressed protein.
