When patients first hear about CAR-T, TCR-T or TIL therapy, one question usually comes first:
How effective is it?
Response rates and clinical trial results are important. But with cell therapy, there is another part of treatment that patients may hear much less about:
How the cells are actually made.
Unlike a conventional drug that can be manufactured in large batches, stored and distributed to hospitals, many cell therapies begin with cells or tissue collected from an individual patient.
Those cells then need to be processed, expanded or genetically modified, tested for quality and, in many cases, transported back to the treatment centre before they can be given to the patient.
This means that manufacturing is not simply a technical process happening in the background.
For many cell therapies, manufacturing is part of the treatment journey itself.
Why is cell therapy different from a conventional cancer drug?
A tablet, antibody drug or chemotherapy product can generally be manufactured before a patient needs it.
Autologous cell therapy works differently.
The treatment may begin with the patient’s own immune cells.
In conventional CAR-T therapy, for example, T cells are collected from the patient's blood and sent to a specialised manufacturing facility. They are genetically modified to express a chimeric antigen receptor, expanded to large numbers, tested and then returned to the hospital for infusion.
The U.S. National Cancer Institute describes an approximately three-to-five-week collection-to-infusion process for CAR-T. Actual timing depends on the product and treatment centre; this is not a promised timeline for an individual patient. [1]
TIL therapy begins from a different source.
Rather than collecting T cells from the bloodstream and adding an artificial receptor, TIL therapy uses immune cells that have already travelled into a patient's tumour.
The National Cancer Institute defines TIL therapy as a treatment in which tumour-infiltrating lymphocytes are removed from a patient's tumour, grown in large numbers in the laboratory and then infused back into the patient. [2]
That difference has important implications for manufacturing.
How is TIL therapy manufactured?
Although individual TIL products and clinical protocols can differ, the overall process may include several stages.
1. Obtaining tumour tissue
TIL therapy generally requires tumour tissue from which tumour-infiltrating lymphocytes can be isolated.
This may involve surgery or another procedure to obtain an appropriate tumour sample.
Not every tumour sample will necessarily be suitable, so the location of the tumour, the patient's health and the treatment protocol all matter.
2. Isolating tumour-infiltrating lymphocytes
The tumour sample is processed in a specialised laboratory.
Immune cells that have entered the tumour are isolated. Among these cells may be T cells capable of recognising cancer-associated targets.
3. Expanding the cells
The selected cells are grown to much larger numbers under controlled manufacturing conditions.
The objective is to produce enough cells for treatment while meeting predefined quality and safety standards.
4. Quality testing
Before a cell product can be released for treatment, it must meet product-specific quality requirements.
Depending on the therapy, testing may include measures related to cell identity, viability, sterility and other manufacturing specifications.
5. Preparing the patient
Once the cell product is ready, patients may need additional preparation before infusion.
Many established TIL protocols include lymphodepleting chemotherapy, which temporarily reduces certain existing immune cells before the expanded TIL product is infused.
Some protocols also use interleukin-2, or IL-2, after TIL infusion to support the transferred cells.
However, treatment protocols are evolving, and lymphodepletion intensity, IL-2 use and supportive care requirements can differ between investigational and approved approaches.
6. Cell infusion and monitoring
The expanded TIL product is then infused into the patient.
Monitoring and supportive care are important because adverse effects may arise not only from the infused cells, but also from lymphodepleting chemotherapy, IL-2 and the patient's underlying cancer.
Source: FDA — AMTAGVI product information and prescribing information
Why does manufacturing time matter?
For a patient with advanced cancer, several weeks can be clinically meaningful.
Cancer does not necessarily stop progressing while a personalised cell product is being manufactured.
This creates one of the central challenges of autologous cell therapy:
Can the patient remain medically eligible and clinically stable until the treatment is ready?
In CAR-T therapy, clinicians often refer to vein-to-vein time—the period between collecting the patient's cells and giving the finished product back to them.
For TIL therapy, the pathway begins with tumour tissue rather than a blood collection, so the process is different. But the underlying issue is similar:
How efficiently can viable tumour tissue be turned into a treatment-ready cell product?
Long manufacturing timelines may create several practical challenges.
A patient may require treatment while waiting.
Their disease may progress.
Their general health may change.
They may develop complications that affect their ability to proceed with lymphodepletion or cell infusion.
This is why faster manufacturing is not simply a matter of convenience.
In some situations, it may affect whether a patient ultimately reaches treatment.
Manufacturing success matters too
Time is only one part of the equation.
For a personalised cell therapy to reach a patient, the manufacturing process must also successfully produce a product that meets the required specifications.
Cell number, cell viability, contamination control and product quality all matter.
This is particularly important when interpreting cell-therapy clinical studies.
A headline may report outcomes among patients who received treatment. But another useful question is:
How many patients entered the treatment pathway, and how many ultimately received the manufactured product?
The distinction can matter when trying to understand real-world treatment accessibility.
The approval of TIL therapy changed the field
TIL therapy moved into a new phase in February 2024 when the U.S. Food and Drug Administration granted accelerated approval to lifileucel (Amtagvi).
The FDA indication covers certain adults with unresectable or metastatic melanoma previously treated with a PD-1 blocking antibody and, for patients whose tumours have a BRAF V600 mutation, a BRAF inhibitor with or without a MEK inhibitor. [3]
It was an important milestone because it established tumour-derived autologous T-cell therapy as an FDA-approved treatment approach for a solid tumour.
However, approval did not eliminate the logistical challenges associated with personalised cell therapy.
For patients, the practical questions extend beyond published outcomes: how long might the pathway take, what could prevent infusion, and what support will be needed? Approval of lifileucel does not mean GC101 or other TIL products have the same approval or access conditions.
CAR-T, TCR-T and TIL: why manufacturing is different
These treatments all use T cells, but they are not manufactured in exactly the same way.
CAR-T therapy generally starts with T cells collected from the blood. The cells are genetically engineered to express a synthetic receptor designed to recognise a particular target on cancer cells.
TCR-T therapy also generally involves genetically modifying T cells, but introduces a tumour-reactive T-cell receptor rather than a CAR. TCR-based approaches can potentially recognise intracellular tumour proteins presented through HLA molecules.
TIL therapy usually starts with lymphocytes already present inside tumour tissue. Conventional TIL approaches seek to expand tumour-reactive immune cells obtained from the tumour itself, without introducing a new receptor. Some investigational TIL approaches also involve genetic modification.
These biological differences create different challenges involving tissue collection, genetic engineering, cell expansion, manufacturing consistency and patient selection.
That is why comparing cell therapies only by a headline response rate can be misleading.
Source: FDA — TECELRA prescribing information (TCR-T example)
Why cell quality may matter as much as cell quantity
Early descriptions of cell therapy often focused on producing very large numbers of T cells.
The field is becoming more sophisticated.
Researchers increasingly study not only how many cells can be produced, but also questions such as:
- Which cells are actually tumour-reactive?
- How exhausted are the T cells?
- Can they continue functioning after infusion?
- How diverse are the tumour targets they recognise?
- How well do the cells survive in the tumour microenvironment?
This is particularly relevant in solid tumours, where cancer cells can be highly heterogeneous and the tumour microenvironment can suppress immune-cell function.
For next-generation TIL approaches, the challenge is therefore not simply to manufacture more cells.
It is to produce the right cells, reliably, in a clinically useful timeframe.
Why logistics and geography matter
Personalised cell therapies also create logistical challenges that conventional medicines do not.
Tumour tissue or collected cells may need to move between:
the hospital → manufacturing facility → treatment centre → patient.
Temperature control, chain of identity, chain of custody, transport timing and coordination between clinical and manufacturing teams all become important.
This becomes even more complex when patients travel internationally for treatment.
An international patient considering cell therapy may need to understand:
- whether tumour tissue can be obtained or transferred;
- where the cell product is manufactured;
- how long the manufacturing process may take;
- whether the patient needs to remain near the treatment centre;
- what treatment may be required while waiting;
- what lymphodepletion or supportive treatment is used;
- how long hospitalisation and local follow-up may be needed.
These questions should ideally be reviewed before making international travel arrangements.
Source: FDA — Considerations for the Development of CAR T Cell Products
Does faster manufacturing mean better therapy?
Not necessarily.
A shorter manufacturing period may reduce waiting time, but it does not itself establish a lower risk of disease progression or a better clinical outcome.
But speed alone does not establish that a therapy is more effective or safer.
Manufacturing changes must still produce cells that meet appropriate quality standards and ultimately demonstrate clinical benefit.
Similarly, different cell therapies cannot be compared simply by stating that one takes fewer days to manufacture than another.
The patient population, cancer type, treatment protocol and clinical evidence all need to be considered.
The next generation of cell therapy is about more than response rates
Cell therapy research is increasingly moving from a single question—
Can these cells attack cancer?
—to a much broader set of questions:
Can they be manufactured consistently?
Can treatment time be shortened?
Can more patients successfully reach infusion?
Can lymphodepletion or supportive treatment be optimised?
Can treatment-related toxicity be reduced?
Can the cells function for longer inside the patient?
Can treatment be delivered at more hospitals?
Can the total cost and logistical burden be reduced?
These questions are likely to become increasingly important as CAR-T, TCR-T and TIL therapy expand into more cancers—particularly solid tumours.
Considering TIL or another cell therapy?
Eligibility for cell therapy is highly individual.
Cancer type, pathology, tumour location, previous treatments, molecular testing, current disease status and general health may all affect whether a particular treatment or clinical trial is relevant.
CancerPath helps international patients organise their medical information and understand potential treatment pathways in China, including emerging cancer therapies and appropriate specialist evaluation.
Ask about a preliminary medical record review
If you would like to explore whether a cell-therapy programme or other advanced treatment option may be relevant, contact us to understand the hospital review process. Agree the recipient and sharing method before sending medical records. This website does not accept record uploads.
Useful documents may include:
- pathology reports;
- recent CT, MRI or PET/CT reports;
- treatment history;
- molecular or genomic testing;
- recent blood test results;
- surgery and hospital discharge summaries;
- current medications.
A preliminary review does not guarantee eligibility for any treatment. Final treatment decisions must be made by the treating medical team after appropriate clinical assessment.
Frequently Asked Questions
How long does TIL therapy take?
There is no single manufacturing timeline that applies to every TIL programme. Timing depends on the product, laboratory process, treatment centre, tumour sample and individual clinical circumstances.
Patients should ask the treatment centre for the expected tissue-to-treatment timeline for the specific programme being considered.
Is TIL therapy the same as CAR-T?
No.
Both are forms of T-cell therapy, but CAR-T cells are typically genetically engineered to recognise a defined surface target, while TIL therapy uses immune cells obtained from within a patient's tumour and expands them outside the body.
Does TIL therapy require surgery?
TIL therapy generally requires tumour tissue. Depending on the tumour and treatment protocol, obtaining adequate tissue may involve surgery or another tumour-sampling procedure.
Is TIL therapy approved?
In the United States, the FDA granted accelerated approval to lifileucel (Amtagvi) in 2024 for a specific population of adults with previously treated unresectable or metastatic melanoma. [4]
Other TIL products and uses in other cancer types remain investigational unless separately approved by the relevant regulator.
Can TIL therapy be used for lung cancer?
TIL therapy is being studied in several solid tumours, including lung cancer, but availability and evidence depend on the specific product and clinical trial.
Patients should not assume that a treatment studied in one cancer type has been proven effective in another.
What information is needed before asking about TIL therapy?
A useful initial medical package usually includes pathology, cancer stage, previous systemic treatments, recent imaging, molecular testing when available, current blood results and information about accessible tumour tissue.
Medical Disclaimer
This article is intended for educational purposes only and does not constitute medical advice, diagnosis or a recommendation for any specific treatment. Cell therapies have important eligibility requirements and potential risks. Patients should discuss treatment options with qualified oncology professionals and the relevant treatment centre.