Direct comparison
Cell Therapy vs Gene Therapy: Operational Split
Cell and gene therapy split on two independent questions, not one. What changes for IND strategy, IBC approval, batch release and 15-year follow-up.
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How do Unmodified cell therapy, Ex vivo gene-modified cells, In vivo gene therapy compare side by side?
The table below compares Unmodified cell therapy, Ex vivo gene-modified cells, In vivo gene therapy across 15 procurement-relevant dimensions, from what is administered through generic-name pattern (usan).
Side-by-side comparison
| Dimension | Unmodified cell therapy | Ex vivo gene-modified cells | In vivo gene therapy |
|---|---|---|---|
| What is administered | Living human cells, processed but not genetically altered (TILs, MSCs, islets, HSPC grafts) | Living human cells carrying transferred or edited genetic material (CAR T, TCR-T, edited HSPCs) | A vector, nucleic acid or engineered nuclease delivered directly to the patient (AAV, oncolytic virus, plasmid) |
| FDA product category | Cellular therapy product; an HCT/P, and a 351 biologic unless it clears every 1271.10(a) criterion | Gene therapy product — FDA lists “ex vivo genetically modified human cells” among its examples | Gene therapy product; 351 biologic |
| Can it avoid an IND entirely? | Yes, but only if all four 21 CFR 1271.10(a) criteria are met (minimal manipulation, homologous use, no combination, and the systemic-effect/autologous test) | No. Genetic modification alters the relevant biological characteristics of the cells, so the minimal-manipulation criterion cannot be met | No. Not an HCT/P at all; the 1271.10(a) route does not exist |
| IBC approval before initiation | Not triggered by the NIH Guidelines — no recombinant or synthetic nucleic acid is transferred | Required. Section III-C bars initiation until IBC approval is obtained from the clinical trial site | Required, on the same Section III-C trigger |
| Donor eligibility screening | Required for allogeneic starting material under 21 CFR 1271 Subpart C; autologous is excepted by 1271.90(a)(1) and must be labelled FOR AUTOLOGOUS USE ONLY | Same as unmodified cells — the starting material is still donated human cells | Not applicable; no human cellular starting material |
| Batch definition | For autologous products, one batch equals one patient; no reserve stock exists | One batch equals one patient for autologous CAR T; allogeneic lots treat several patients and need extra testing | One vector lot serves many patients — a conventional biologics batch problem |
| Terminal sterilisation | Impossible — the cells must stay viable, so qualified aseptic processing is the only control | Impossible, for the same reason; aseptic processing must be validated for licensure (21 CFR 211.113) | Sterilising filtration is often available, which removes the single hardest constraint in cell manufacturing |
| Class-specific release tests | Identity, viability, purity and a potency measure on patient-derived material whose properties vary with disease state and prior treatment | Adds vector copy number per transgene-positive cell on the certificate of analysis for every lot, plus transduction efficiency | Adds vector strength as transducing units per mL, plus vector identity, purity and biological activity |
| Replication-competent retrovirus testing | Not applicable | Applies to retroviral and lentiviral vector products: 1% or 10⁸ pooled transduced cells (whichever is less) by co-culture on a permissive line | Applies to retroviral vector supernatant: at least 5% of the lot, sized for a 95% chance of detecting 1 RCR per dose equivalent |
| FDA long-term follow-up | No gene-therapy LTFU obligation; follow-up is whatever the clinical protocol needs | 15 years for gammaretroviral, lentiviral and transposon vectors; up to 15 years for genome-editing products | Up to 5 years for AAV; up to 15 years for latency-capable or persistent vectors; none for plasmid alone |
| Patient RCR/RCL monitoring | None | Pre-treatment, then 3, 6 and 12 months, then yearly for up to 15 years — discontinuable if the first year is clean | Same schedule where a retroviral vector is administered directly |
| Infusing an out-of-specification lot | Permitted under EU GMP Part IV 11.5 for a life-threatening condition when autologous or matched-donor, with a documented risk evaluation and the physician’s recorded agreement | Same route available — and routinely needed, since remaking the batch means re-collecting from a patient who may have progressed | No equivalent. The lot is rejected and another is released |
| EU ATMP class | Somatic cell therapy medicinal product, or tissue-engineered product if it repairs or replaces tissue | Gene therapy medicinal product | Gene therapy medicinal product |
| EU GMO consent before the trial | Not required | Required per Member State under Directive 2001/18/EC or 2009/41/EC, in parallel with the clinical trial application | Required, and typically the heavier environmental risk assessment of the two |
| Generic-name pattern (USAN) | One word ending in -cel (lifileucel, remestemcel-L, donislecel) | Two words: a -gene word plus a -cel word (axicabtagene ciloleucel, exagamglogene autotemcel) | Two words: a -gene word plus a -vec word (onasemnogene abeparvovec, voretigene neparvovec) |
Common questions
Common questions about Unmodified cell therapy vs Ex vivo gene-modified cells vs In vivo gene therapy
Is CAR T cell therapy a cell therapy or a gene therapy?
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Operationally it is both, and regulatorily FDA treats it as a gene therapy product: the agency lists ex vivo genetically modified human cells among its examples of human gene therapy products. That means a CAR T programme carries IBC approval, vector copy number release testing, replication-competent retrovirus testing and 15-year long-term follow-up on top of every cell-handling obligation.
Does a cell therapy trial need Institutional Biosafety Committee approval?
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Only if recombinant or synthetic nucleic acid is deliberately transferred into participants. NIH Guidelines Section III-C is triggered by the nucleic acid, not by the cell, so an unmodified TIL or MSC trial generally sits outside it while a CAR T trial cannot start until IBC approval is obtained from the clinical trial site.
Can a cell therapy reach patients without an IND or BLA?
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Only an unmodified one, and only if it clears all four criteria in 21 CFR 1271.10(a). FDA has stated that where information does not exist to show the processing meets the minimal-manipulation definition, it treats the processing as more than minimal manipulation — so the default answer is no.
How long is long-term follow-up for a gene therapy?
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FDA recommends 15 years for integrating vectors (gammaretroviral, lentiviral, transposon), up to 15 years for genome-editing products and latency-capable vectors, and up to 5 years for AAV. Duration is set by the vector, not by whether cells were involved.
Why can a failing autologous product still be infused when a vector lot cannot?
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Because there is no second batch. EU GMP Part IV section 11.5 allows administration of an out-of-specification autologous or matched-donor product for a life-threatening condition, provided the manufacturer supplies a risk evaluation and records the treating physician’s agreement. An in vivo vector lot is simply rejected and remade.
What does the -cel ending in a product name tell me?
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Under the USAN scheme, -cel marks the cell component and -vec marks a non-replicating viral vector. A single -cel word means cells with no gene transfer; a -gene word paired with a -cel word means gene-modified cells; a -gene word paired with a -vec word means an in vivo vector.
