So far, TIL therapy has mostly been used in clinical trials for melanoma patients whose melanoma has spread and who haven’t been helped by other treatments. It’s also possible that TIL therapy may work for patients who haven’t had other treatment for their melanoma, but this is still being investigated.
Tumour-infiltrating lymphocyte (TIL) Therapy
What is a Tumour-infiltrating lymphocyte (TIL) and why are they being researched?
Lymphocytes, or white blood cells, are an important part of the immune system (the body’s natural defence) that helps the body fight off infections or recognise and attack cancer cells.
Lymphocytes, made up of various T cells and B cells, go around the body as a natural defence system trying to find cells that shouldn’t be there, attacking and killing them.
As a melanoma grows, some T-cells can recognise that the melanoma cells are abnormal, and they move from the blood stream to inside the melanoma. These are the tumour-infiltrating lymphocytes, or TILs and they will recognise and try to kill the melanoma cells.
However, sometimes melanoma cells can stop TILs from attacking and killing them by quickly changing the targets that the TILs recognise or by giving off signals that can weaken the immune system’s response. Therefore, researchers have been looking at how to make the TILs more effective at fighting melanoma.
TIL therapy is a personalised treatment tailored to an individual patient’s melanoma using the patient’s own immune system. It is a very challenging one-off treatment that can lead to a long-term response. TIL therapy has been described like a transplant used in people with blood cancers like leukaemia, lymphoma and myeloma. Most side-effects are from the high-dose chemotherapy treatment or the IL-2 treatment (which helps stimulate the immune system and activity of TILs in the body). As with all ‘transplant’ treatments, this treatment requires a high level of patient support, before, during and after treatment.
Understanding TIL Therapy
To support the information on this page, we have worked with Dr. Elaine Vickers to create a video which explains how TIL (Tumour-infiltrating lymphocyte) Therapy works, who TIL Therapy is for and its use in the treatment of melanoma.
How can TILs be used to treat melanoma?
TIL therapy is where TILs are taken directly from the patient’s melanoma itself as they already recognise many targets on the melanoma cells. This makes the TILs very useful in treating melanoma because they can already identify it by themselves without having to be altered.
To effectively use TILs to treat melanoma researchers can help them to overcome the way that the melanoma cells can hide from the immune system, which allow it to grow and multiply. Because it uses the immune system, TIL therapy is a type of immunotherapy, and it can also be referred to as personalised cancer treatment.
By growing the TILs to very large numbers and giving them back to the patient researchers believe that the patient’s body then has a much larger army of immune cells that are already trained to recognise and attack that patient’s specific melanoma.
Lifileucel is a TILs treatment that is going through the approval process in the UK at the moment and in June 2025, the 5 year follow up trial results were published. For more information see here.
Lifileucel is awaiting its medicines license in the UK, by the Medicines and Healthcare products Regulatory Agency (MHRA). If it is approved, lifileucel may be available as treatment privately in the UK, before it is available on the NHS.
A NICE (National Institute for Health and Social Excellence) committee review is pending for lifileucel and the expected guidance publication date is currently 10th July 2026. If NICE guidance is approved this means lifileucel would be available on the NHS in England.
The Scottish Medicines Consortium (SMC) still has it’s review and publication dates pending.
What is the treatment process for TIL therapy?
TIL therapy is a one-off treatment that is highly technical and expensive.
TILs are isolated from a patient’s own melanoma. Each patient will be assessed to check that doctors can access the melanoma tissue in their body (the tumour must be ‘resectable’), which in a small number of cases may not be possible.
A small part of the melanoma is removed by a minor surgical operation, and this tiny part of the melanoma is broken down into smaller parts in a laboratory. Specific chemicals are added to encourage the TILs to grow in large numbers, which can take about 3-4 weeks. However, researchers are working on being able to speed up this process to be able to get treatment to patients more quickly.
TIL therapy is an intense treatment, and all patients will be admitted to hospital before treatment starts and will be an inpatient for about 2 weeks.
Before receiving the TILs back into their body, the patient will receive treatment with high dose chemotherapy infusions (i.e. through a vein in their arm) over a few days. This is to reduce the number of natural immune cells in the blood and make room for the new TILs that will be given to them to fight the melanoma.
(You can learn more about TILs treatment by watching Esther and Jane’s story about her private treatment in Israel).
The billions of TILs that have been grown in the laboratory will be given back to the same patient by giving a single infusion into a vein (i.e. in the arm). The high numbers of TILs that will then be circulating in the patient’s body are thought to help their immune system fight the melanoma more effectively, as there will be a higher number of TILs that are available to find, attack and kill the melanoma cells.
This method is known as ‘autologous’, which means that the TILs are given back as treatment to the same patient from which the melanoma cells were originally taken.
Immediately after receiving the infusion of TILs the patient will receive some immune-modulating treatment called IL-2 as an infusion (i.e.into a vein in the arm) for a number of days. This treatment is to help stimulate the immune system and the TIL activity in the body.
TIL therapy is a one time treatment and for the duration of their stay doctors will very closely monitor patients for any side effects or reactions to the therapy at each stage of the treatment process to ensure that they are well before they can go home.
What are the possible side effects of TIL therapy?
Most side effects that have been seen with TIL therapy come from the chemotherapy treatment given before or the IL-2 treatments given after the one-off TIL infusion. Doctors are used to managing these types of side effects, but they can still be quite harsh on the body.
Patients will be given some medicines to try to prevent more common side effects such as nausea and vomiting, or diarrhoea. Other possible side effects of high-dose chemotherapy and IL-2 can include tiredness, hair loss, bruising and bleeding, fevers or chills, skin rash, mouth ulcers, dizziness, confusion, low blood pressure or increased risk of catching infections.
Side effects relating to the TIL infusion are less common, but patients may develop a reaction including shortness of breath, chills, and fever shortly after the infusion of TILs; this is usually very short-lived and can be treated quickly. Other rare side effects from TILs can develop much later and may be due to it’s action on the immune system.
TIL therapy is a one-off treatment, but it is very intense. As well as looking at how effective these treatments are at treating melanoma, doctors are still studying how well patients cope with the therapy and what side effects they may experience during the whole treatment process.
Whilst we recognise that TILs can be quite a challenging and at times brutal treatment and you have to be physically strong to tolerate it, we do also hear that TILs provides hope and one patient said that they owe the TILs treatment everything and more.
There are currently some ongoing clinical trials in the UK looking at TILs. You can have a look at the ones that are open to recruitment now on our Melanoma TrialFinder.
Resources used to create this page:
Qin SS, Melucci AD, Chacon AC, Prieto PA. 2021; 10(4):808. https://doi.org/10.3390/cells10040808
Rohaan, M.W., van den Berg, J.H., Kvistborg, P. et al. Adoptive transfer of tumor-infiltrating lymphocytes in melanoma: a viable treatment option. j. immunotherapy cancer 6, 102 (2018). https://doi.org/10.1186/s40425-018-0391-1
Rohaan, M.W., Borch, T.H., van den Berg, J.H. N Engl J Med 2022; 387:2113-2125 https://DOI.org/10.1056/NEJMoa2210233
https://www.cancer.gov/about-cancer/treatment/types/immunotherapy/t-cell-transfer-therapy
https://www.cancerresearch.org/treatment-types/adoptive-cell-therapy
Theresa Medina et al. Long-Term Efficacy and Safety of Lifileucel Tumor-Infiltrating Lymphocyte Cell Therapy in Patients With Advanced Melanoma: A 5-Year Analysis of the C-144-01 Study. J Clin Oncol 43, 3565-3572(2025). DOI:10.1200/JCO-25-00765