Cell Gene Therapy Explained: Where CAR-T Meets CRISPR
Introduction: Why “Cell Therapy” and “Gene Therapy” Keep Getting Confused
Patients, caregivers, and even experienced healthcare professionals often use “cell therapy” and “gene therapy” as if they mean the same thing. They do not. The U.S. Food and Drug Administration (FDA) regulates them as distinct categories, each with its own definitions and review considerations.
The core difference is simple:
- Cell therapy introduces living cells into a patient to replace, restore, or attack.
- Gene therapy introduces genetic material to add, silence, or correct a gene.
The confusion comes from products that combine both. Most explainers stop at a single example, usually CAR-T. This article goes further, covering CAR-T, the CRISPR-based therapy Casgevy, and the emerging 2026 hybrids, including in vivo CAR-T and base-edited cell products, that blur the line even further.
The organizing lens throughout is the FDA’s own regulatory framework, as applied by its Center for Biologics Evaluation and Research (CBER), rather than generic marketing language. The article also addresses inconsistent market-sizing data openly instead of repeating a single figure as fact. It serves as a foundational, plain-language explainer for general readers, not a disease-specific or manufacturing-specific deep dive.
What Is Cell Therapy? What Is Gene Therapy? The FDA’s Regulatory Lens
Both modalities fall under CBER, which oversees cellular therapy products, human gene therapy products, and certain related devices. It uses the Public Health Service Act and the Federal Food, Drug, and Cosmetic Act as its legal authority.
This shared regulatory home is a major reason the two categories are so often conflated in public discussion. When one agency office reviews both, it is easy to assume they are the same thing.
How CBER Defines Cell Therapy
Cell therapy involves giving a patient living, whole cells to replace, restore, or enhance biological function, or to directly attack disease such as cancer.
Cell therapies vary along two important dimensions:
- Source: Autologous therapies use the patient’s own cells. Allogeneic therapies use cells from a donor.
- Modification: Some cell therapies use unmodified cells. Others use cells that have been engineered before being given to the patient.
How CBER Defines Gene Therapy
One regulatory fact is especially important: the FDA considers any use of CRISPR/Cas9 gene editing in humans to be gene therapy, regardless of whether cells are used to deliver the edit.
Gene therapy is therefore defined by the type of intervention, meaning the alteration of genetic material or cell biology. It is not defined by the delivery vehicle alone.
Why FDA Created One Office for Both, and Still Keeps Them Separate
In 2023, CBER created the Office of Therapeutic Products (OTP), a “super office” that oversees both cell and gene therapies. Within OTP, however, the FDA maintains separate divisions:
- Gene Therapy CMC (chemistry, manufacturing, and controls)
- Cellular Therapy/Human Tissue CMC
This structure shows that regulators still treat the manufacturing and review pathways as distinct, even as individual products increasingly blend both approaches. The rest of this article uses this structure to classify each example.
Where the Line Blurs: CAR-T as Genetically-Engineered Cell Therapy
CAR-T is the textbook example of convergence. It is regulated as a cell therapy, but it depends entirely on genetic modification to work. Understanding why CAR-T is classified this way makes the less familiar hybrid products later in this article much easier to follow.
The Mechanism: Inserting a Gene to Engineer an Immune Cell
The basic CAR-T process has three steps:
- Collection: T cells, a type of immune cell, are extracted from the patient’s blood.
- Engineering: In a lab, a viral vector inserts a gene that instructs the T cells to produce a chimeric antigen receptor (CAR), a surface protein that recognizes a specific marker on cancer cells.
- Reinfusion: The engineered cells are infused back into the patient, where they seek out and attack cancer cells.
Under the FDA’s framework, CAR-T qualifies as a cell therapy because the living cell is the therapeutic agent. The inserted gene is the mechanism that makes it work, but the product delivered to the patient, and the agent doing the therapeutic work, is the cell.
The 2026 FDA-Approved CAR-T Landscape
Six original FDA-approved autologous CAR-T products are on the market for blood cancers:
- Kymriah
- Yescarta
- Tecartus
- Breyanzi
- Abecma
- Carvykti
They have been joined by Aucatzyl (obecabtagene autoleucel) for B-cell precursor acute lymphoblastic leukemia (ALL).
As of 2026, no allogeneic (“off-the-shelf”) CAR-T product has received FDA approval. Every approved CAR-T therapy is still made individually for each patient, which drives much of the manufacturing complexity discussed later.
Safety Considerations Unique to Genetically-Engineered Cell Therapy
CAR-T carries well-characterized risks that differ from most traditional gene therapies:
- Cytokine release syndrome (CRS): An intense inflammatory response triggered as the engineered cells activate. It occurs in an estimated 70% to 90% of CAR-T patients.
- Immune effector cell-associated neurotoxicity syndrome (ICANS, also called CRES): A second major toxicity affecting the nervous system.
Both require specialized monitoring. Some patients need ICU-level care and drugs such as tocilizumab.
In 2025, the FDA eliminated formal Risk Evaluation and Mitigation Strategy (REMS) requirements for the six original autologous CAR-T products. Safety labeling on CRS and neurotoxicity remains. The change reflects growing clinical familiarity with how to recognize and manage these risks.
Casgevy: When Gene Editing Is Delivered Through Cells
If CAR-T is a cell therapy that depends on genetics, Casgevy (exagamglogene autotemcel, or exa-cel) is the reverse: a product built on cells but classified as a gene therapy, because its therapeutic action is genetic correction. This section focuses on classification logic rather than sickle cell disease clinical detail, which is covered elsewhere.
The Mechanism: Ex Vivo CRISPR Editing of a Patient’s Own Stem Cells
Casgevy uses a non-viral, ex vivo CRISPR/Cas9 process. A patient’s own hematopoietic stem and progenitor cells (the cells that give rise to blood cells) are collected and edited outside the body. The edit targets the erythroid-specific enhancer region of the BCL11A gene, which normally suppresses fetal hemoglobin. Disrupting it reactivates fetal hemoglobin production, which can compensate for the defective adult hemoglobin in sickle cell disease and transfusion-dependent beta thalassemia.
The FDA approved Casgevy in December 2023 as the first CRISPR-based gene-editing therapy in the United States.
The 2026 Regulatory Expansion
On July 1, 2026, the FDA expanded Casgevy’s approval to include patients as young as 2 years old, down from the previous threshold of 12 and older. As a result, roughly 5,500 additional children in the U.S. became eligible.
Why FDA Classifies Casgevy as Gene Therapy Despite Its Cell-Based Delivery
The contrast with CAR-T clarifies the logic:
| CAR-T | Casgevy | |
|---|---|---|
| Role of the cell | The therapeutic agent | A delivery vehicle |
| Role of the genetic change | Turns an ordinary T cell into a cancer-fighting cell | Is itself the treatment: a permanent genetic edit |
| Genetic method | Viral vector gene insertion | CRISPR/Cas9 editing |
| FDA classification | Cell therapy | Gene therapy |
The deciding factor is the principle introduced earlier: any CRISPR/Cas9 editing in humans is gene therapy. Even though Casgevy’s edited cells are returned to the patient, the treatment is the edit.
The 2026 Convergence Trend: Hybrid Products Blurring the Line Further
CAR-T and Casgevy are the anchor examples. A newer wave of products makes the cell-versus-gene distinction even harder to draw, and this is where most existing explainers stop short.
In Vivo CAR-T: Engineering Immune Cells Inside the Body
Traditional CAR-T is made ex vivo: cells are removed, modified in a lab, and reinfused. In vivo CAR-T aims to engineer T cells directly inside the patient’s body.
Research published in Nature by Justin Eyquem, Jennifer Doudna, and Julia Carnevale, researchers affiliated with UCSF, UC Berkeley, and the Innovative Genomics Institute, working alongside Azalea Therapeutics, demonstrated in vivo CAR-T made using CRISPR for the first time. In mouse studies, the precisely edited cells cleared tumors.
Researchers point to two potential benefits:
- Eliminating chemotherapy conditioning, which patients typically receive before CAR-T infusion
- Dramatically reducing manufacturing cost and complexity, since no individualized lab processing would be needed
Base-Edited CAR-T: A New Layer of Genetic Precision
In January 2026, the New England Journal of Medicine published a study on universal base-edited CAR7 T cells for T-cell acute lymphoblastic leukemia.
Standard CAR-T adds a gene. Base editing goes further by changing individual DNA “letters” at precise locations, without cutting both strands of DNA. This allows developers to make targeted adjustments, such as switching off genes that could cause the engineered cells to attack each other or be rejected by the patient.
The word “universal” matters. It signals a design meant to work across patients rather than being made for one individual, a step toward the off-the-shelf CAR-T that does not yet exist on the market.
mRNA-Encoded CAR-T and Other Emerging Hybrids
The American Society of Gene & Cell Therapy (ASGCT), in its Q2 2026 Landscape Report produced with Citeline, noted that mRNA-encoded CAR-T innovation accelerated, with new entrants in that quarter matching all of 2025’s total. mRNA delivers temporary genetic instructions rather than permanent DNA changes, offering another route to engineering immune cells.
The same report recorded eight new gene, cell, and RNA therapy approvals globally in Q2 2026 alone, including treatments for hearing loss, cancer, and limb ischemia. The pace signals how quickly this convergence space is moving.
What This Means for the Cell vs. Gene Therapy Distinction Going Forward
As more products combine genetic editing with cellular delivery, the FDA’s institutional separation between Gene Therapy CMC and Cellular Therapy CMC will likely face growing classification complexity. An in vivo CRISPR product that creates CAR-T cells inside the body raises an obvious question: is it a cell therapy, a gene therapy, or both?
The most durable way to make sense of future products is to understand the underlying logic (is the living cell the therapeutic agent, or is the genetic change the treatment?) rather than memorizing which bucket each product falls into.
How Big Is the Convergence Trend? Pipeline and Approval Momentum
Beyond individual examples, the broader development pipeline shows the scale of the convergence.
The Pipeline Numbers Tell the Story
According to ASGCT/Citeline data, as of early 2026 there were approximately:
- 2,217 gene therapies in active development, a figure that includes genetically modified cell therapies
- 875 non-genetically-modified cell therapies
The key insight is that a large share of what is commonly called “cell therapy” is actually gene-modified. Convergence is the norm, not the exception.
A Rebound in Approvals After a Quiet Start to 2026
The eight approvals recorded in Q2 2026 followed a comparatively quiet first quarter. This rebound is evidence that the regulatory pathway for hybrid and converged products is maturing in real time, not as a future hypothetical.
Market Size Confusion: Why Research Firms Disagree
Many articles cite a single market figure as fact. A more transparent approach is to show why those figures conflict.
The Numbers Problem: Estimates Ranging Widely
Estimates of the 2026 global cell and gene therapy market vary dramatically by research firm, from roughly $10.4 billion to over $44 billion. At least one forecast places the combined figure near $25.78 billion.
Despite this variance, most analysts agree on double-digit compound annual growth, roughly 17% to 31%, through the early-to-mid 2030s, driven by CRISPR, CAR-T, and scalable manufacturing.
Root Cause: Inconsistent Scope Definitions
The discrepancies largely stem from different definitions of what counts as “the market.” Reports may:
- Count only approved commercial products
- Include R&D and manufacturing services
- Separate “cell” and “gene” therapy into distinct categories, or combine them into one figure
This connects directly to the FDA classification theme. If regulators and analysts define the categories differently, and analysts disagree among themselves, comparing headline numbers across sources is inherently misleading.
Contradictory Market Share Claims: Cell vs. Gene Therapy
One report states that cell therapy, including CAR-T and stem-cell applications, holds 61.2% of the combined market. Another shows gene therapy manufacturing leading with nearly 64% of manufacturing-segment revenue.
This is not necessarily an error. The two reports measure different things: overall market share versus manufacturing-segment revenue. And because CAR-T can reasonably be counted in either category, how a report classifies it can shift the totals significantly.
How to Read Market Sizing Data Critically
For investors, students, and journalists, a few practical habits help:
- Check the scope. Confirm what each report includes and excludes before comparing figures.
- Note how CAR-T and gene-modified cell products are categorized.
- Favor growth trends over absolute figures. Growth rates tend to be more consistent across competing publishers than dollar totals.
Manufacturing Complexity: The Real Driver Behind Cell vs. Gene Therapy Differences
These classification distinctions have real operational consequences.
Autologous vs. Allogeneic: Why Off-the-Shelf CAR-T Doesn’t Exist Yet
All approved CAR-T products are autologous, so each patient’s treatment is manufactured individually. Cells must be collected, shipped, engineered, quality-tested, and returned, a process that creates complexity and turnaround-time challenges, particularly for patients with aggressive cancers.
Allogeneic approaches would use donor cells to create batches that could be stored and given to many patients. These remain in development, and the base-edited “universal” designs described above are among the efforts to make them viable.
Why In Vivo Approaches Could Reduce Manufacturing Burden
In vivo CAR-T could remove entire steps of ex vivo cell processing: no cell collection, no individualized lab engineering, and no reinfusion logistics. If these approaches succeed in later-stage human trials, the implications for scalability and patient access could be substantial, especially for treatment centers without specialized cell-processing infrastructure.
The Broader Cost-Complexity Relationship
One-time curative cell and gene therapies tend to sit at the high end of therapeutic costs industry-wide. The main reasons are manufacturing complexity, personalization, and the fact that a single treatment may replace years of ongoing care. This cost structure is a major reason health systems and payers are actively exploring new reimbursement and access models for these therapies.
What This Means for Patients, Caregivers, and Professionals
For Patients and Caregivers: Questions Worth Asking
Patients and caregivers may find it useful to ask their care team:
- Is this treatment classified as a cell therapy, a gene therapy, or a hybrid?
- Is it autologous (made from the patient’s own cells) or allogeneic (from a donor)?
- Is it made ex vivo and given once, or does it modify cells in vivo, inside the body?
- What monitoring is required, and for how long?
Understanding the classification helps patients anticipate what lies ahead. A CAR-T patient, for example, should expect close monitoring for CRS and ICANS, while a gene-edited therapy may involve long-term follow-up to track the durability and safety of a permanent genetic change.
For Industry Professionals and Investors: Why the Distinction Still Matters
Because the FDA maintains separate CMC divisions for gene and cellular therapy, regulatory and manufacturing pathways can still differ meaningfully, even for converged products. Professionals tracking the field should follow the ASGCT/Citeline quarterly landscape reports for current pipeline and approval data, since figures shift quickly from quarter to quarter.
Conclusion: One Field, Two Frameworks, and a Fast-Converging Future
Cell therapy and gene therapy remain formally distinct under the FDA’s regulatory framework. Yet the most clinically significant products of 2026, including CAR-T, Casgevy, and emerging in vivo and base-edited hybrids, increasingly live at their intersection.
Understanding the FDA’s definitional logic, meaning whether the cell is the therapeutic agent or the genetic change is the treatment, is more useful than memorizing individual product classifications. That logic will remain relevant as new hybrids emerge.
Inconsistencies in market sizing and terminology across the industry are likely to persist, so reading data sources critically is an ongoing necessity rather than a one-time lesson. As in vivo and base-edited approaches mature, the line between “cell” and “gene” therapy may matter less to patients than the practical questions of safety, durability, and access.
Continue Exploring Cell and Gene Therapy
This explainer touches only briefly on several topics that deserve deeper treatment. Readers can explore Adiamed’s related content on CAR-T treatment specifics, Casgevy and sickle cell disease, and broader cell therapy reviews for more detail on each.
The in vivo and base-edited therapy space is developing quickly through 2026 and beyond. Readers who want to stay current can subscribe to or follow Adiamed for ongoing, plain-language coverage of the developments shaping cell and gene therapy.
