TIL Therapy: How Tumor-Infiltrating Lymphocyte Therapy Treats Advanced Melanoma
Updated: 5 days ago
Written and medically reviewed by Dr. Baraa Alnahhal, MD · Last reviewed: October 2026 · How we review
Quick Answer: What is TIL therapy?
Tumor-infiltrating lymphocyte (TIL) therapy is a one-time cancer immunotherapy that collects immune cells from a patient's own tumor, multiplies them into billions in a lab and returns them through an IV. It treats advanced melanoma that has not responded to standard treatment, and the full process takes about 10 weeks. [1][2]
What the research says
TIL therapy beat a standard immunotherapy drug in a phase 3 trial. In 168 people with advanced melanoma, median time without cancer progression was 7.2 months with TIL therapy versus 3.1 months with ipilimumab, and tumors shrank in 49% versus 21% of patients. All TIL patients had severe (grade 3+) side effects, mainly low blood counts from chemotherapy. (Rohaan et al., N Engl J Med, 2022) [3]
TIL therapy helped people whose melanoma had stopped responding to other drugs. In a phase 2 study of 66 patients who had already received an average of 3.3 prior treatments, 36% had tumor shrinkage and 80% had their disease controlled; many responses were still ongoing after a median follow-up of 18.7 months. (Sarnaik et al., J Clin Oncol, 2021) [4]
Key takeaways
TIL therapy uses your own tumor-fighting immune cells, grown into billions in a lab.
It is approved for melanoma that can't be removed with surgery or has spread and hasn't responded to first-line treatments.
It is a one-time treatment that takes about 10 weeks, including about 2 weeks in hospital.
Most side effects come from the chemotherapy and IL-2 steps, not from the TIL cells themselves.
What are tumor-infiltrating lymphocytes?
Tumor-infiltrating lymphocytes (TILs) are immune cells that move directly into a tumor to attack it. [1]
Your body has many immune cells that patrol for threats. TILs are different because they go inside the tumor itself. There, they learn the tumor's weak points and how to destroy it. [1]
The problem is numbers. Your immune system usually doesn't make enough TILs to win the fight on its own. TIL therapy solves this by growing your TIL "army" by the billions. [1]
How does TIL therapy work?
TIL therapy works by removing part of a tumor, growing the TILs inside it in a lab and infusing the expanded cells back into the patient. [1]
It is a type of immunotherapy, which means it helps your immune system recognize and fight cancer cells. Because the cells come from your own tumor, the treatment is highly personalized. [1]
Which cancers does TIL therapy treat?
TIL therapy is approved to treat advanced melanoma that can't be treated with surgery alone or that has spread to other parts of the body. [1][5]
Lifileucel (Amtagvi®) became the first TIL therapy approved by the U.S. Food and Drug Administration (FDA) in 2024. [1][5] You may be a candidate if your melanoma has not responded to the standard treatments oncologists usually try first. [1]
Researchers are also studying TIL therapy for other solid tumors: [1]
Cancer type | Status |
Advanced or metastatic melanoma | FDA-approved (lifileucel) |
Breast cancer | Under study |
Cervical cancer | Under study |
Colon cancer | Under study |
Head and neck cancer | Under study |
Non-small cell lung cancer | Under study |
What happens during TIL therapy?
TIL therapy happens in five main steps, from tumor removal to an IL-2 infusion that activates the new cells. [1]
Step | What happens | How long |
1. Tumor removal | A surgeon removes a grape-sized piece of tumor under anesthesia | One procedure |
2. TIL harvest and expansion | A lab collects the TILs and multiplies them | About 5 weeks |
3. Chemotherapy | You're admitted to hospital for chemotherapy that makes room for the new TILs | 5 to 7 days (about 2 hours per infusion) |
4. TIL infusion | You receive your expanded TILs through an IV | One time, about 2 hours |
5. Interleukin-2 (IL-2) infusions | IL-2 switches the TILs on to fight the cancer | 3 to 5 days (about 2 hours per dose) |
Step 1: Removal. You receive anesthesia, so you won't feel pain. The sample is sent straight to the lab. [1]
Step 2: Lab growth. The lab harvests TILs from the sample and grows more of them, then sends them back to your care team. [1]
Step 3: Chemotherapy. These chemotherapy infusions lower your existing immune cells so the new TILs have space to work. [1]
Step 4: TIL infusion. This is the main treatment, given only once. [1]
Step 5: IL-2. This immunotherapy drug activates the infused TILs against the tumor. [1]
How long does TIL therapy take?
TIL therapy takes about 10 weeks from tissue removal to recovery, with a hospital stay of about 2 weeks. [1]
That time includes the lab waiting period and your recovery. After treatment, you stay in hospital for a few days so your team can monitor you. For several more weeks, you'll stay within driving distance of the hospital in case you need urgent care for side effects. [1]
How effective is TIL therapy for melanoma?
TIL therapy is effective for many people with advanced melanoma that other treatments could not control. [1][3][4]
In a long-term study that followed patients for four years, about 7 in 10 people had improvement or no cancer growth, and about 3 in 10 had tumors that shrank or disappeared. [1][6]
In a large phase 3 trial, TIL therapy more than doubled the time patients lived without their cancer getting worse compared with the immunotherapy drug ipilimumab. [3]
What are the benefits of TIL therapy?
TIL therapy's main benefits are that it is personalized, long-lasting and helpful for melanoma that was previously untreatable. [1]
Targeted: It focuses on cancer cells while sparing healthy cells. [1]
Long-lasting: TILs can stay in your body for years and keep fighting tumors after the infusion. [1]
One-time: You receive the TIL infusion only once. [1]
New option: It offers hope when standard melanoma treatments have stopped working. [1]
What are the side effects of TIL therapy?
TIL therapy side effects come mainly from the chemotherapy and IL-2 steps, not from the TIL infusion itself. [1]
Common side effect | Usually linked to |
Diarrhea | Chemotherapy / IL-2 |
Fatigue | Chemotherapy / IL-2 |
Fever and chills | IL-2 |
Irregular heartbeat (arrhythmia) | IL-2 |
Low blood pressure | IL-2 |
Nausea and vomiting | Chemotherapy / IL-2 |
Rash | IL-2 |
Rarely, IL-2 can cause a serious problem called capillary leak syndrome, where fluid leaks from small blood vessels. Lifileucel carries an FDA boxed warning for treatment-related deaths, long-lasting very low blood counts, severe infections, and heart, lung and kidney problems, so it is given only at specialized centers. Your care team will review every risk with you before treatment starts. [1]
For a deeper look at managing these effects, see our guide to immunotherapy side effects.
What is recovery like after TIL therapy?
Recovery after TIL therapy usually takes two weeks or more after the last IL-2 infusion before you start feeling better. [1]
Your body needs time to recover from all the treatment steps. During your hospital stay, your team will do regular exams and blood tests, give medicines to reduce side effects and watch closely for complications. [1]
When should you call your doctor after TIL therapy?
You should call your doctor after TIL therapy if you have signs of infection or any unexpected or severe side effects. [1]
Don't second-guess yourself. If something feels "off" after treatment, contact your care team right away. [1]
Conclusion
TIL therapy turns your own immune cells into a powerful, personalized treatment. It is a demanding process, with surgery, lab growth, chemotherapy and IL-2 over about 10 weeks. But for people with advanced melanoma that hasn't responded to other options, it offers durable results that were not possible before. If your oncologist suggests TIL therapy, ask about your timeline, the expected benefits and the risks for your specific case.
Want clear, trusted guides on cancer care? Explore more from our Diseases & Conditions library, and start with our complete immunotherapy for cancer guide.
FAQ
What is TIL therapy?
TIL therapy is a type of immunotherapy that removes tumor-fighting immune cells from a patient's tumor, multiplies them in a lab and infuses them back. It is used to treat advanced melanoma that has not responded to standard treatments.
What does TIL stand for?
TIL stands for tumor-infiltrating lymphocyte. TILs are immune cells that move directly into a tumor to attack it.
Who is a candidate for TIL therapy?
Candidates for TIL therapy are people with melanoma that can't be treated with surgery alone or has spread, and that hasn't responded to first-line treatments. Your oncologist decides whether you qualify.
How long does TIL therapy take?
TIL therapy takes about 10 weeks from tissue removal to recovery. The hospital stay is close to two weeks.
Is TIL therapy a one-time treatment?
Yes, TIL therapy is a one-time treatment. You receive the TIL infusion once, and the cells can stay in your body for years.
What are the side effects of TIL therapy?
The most common side effects of TIL therapy are diarrhea, fatigue, fever, chills, irregular heartbeat, low blood pressure, nausea, vomiting and rash. They mostly come from chemotherapy and IL-2, not from the TIL cells.
How successful is TIL therapy?
In a four-year follow-up study, about 7 in 10 people had improvement or no cancer growth after TIL therapy. About 3 in 10 had tumors that shrank or disappeared.
When should I call my doctor after TIL therapy?
Call your doctor after TIL therapy if you notice signs of infection or unexpected or severe side effects. If something feels "off," contact your care team right away.
Is TIL therapy FDA-approved?
Yes. In 2024 the FDA approved lifileucel (Amtagvi), the first TIL therapy, for certain adults with advanced melanoma that has grown after other treatments. Your oncologist can tell you whether you qualify.
Why is chemotherapy given before TIL therapy?
A short course of chemotherapy is given before the TIL infusion to clear out some of your existing immune cells. This makes room for the new TIL cells to grow and fight the cancer.
Related Reading
Melanoma: A Comprehensive Guide to Early Detection and Treatment explains melanoma, how it is found and the main treatment options.
CAR T-Cell Therapy: How It Works, Side Effects, and Recovery describes another cell therapy that engineers immune cells to fight cancer.
Immunotherapy for Cancer: How It Works and What to Expect covers the main types of cancer immunotherapy and what to expect.
Immunotherapy Side Effects: Managing Your Cancer Treatment Journey explains common immunotherapy side effects and how they are managed.
References
Cleveland Clinic. What Is Tumor-Infiltrating Lymphocyte (TIL) Therapy? Cleveland Clinic. Last updated April 23, 2025. https://my.clevelandclinic.org/health/treatments/tumor-infiltrating-lymphocyte-til-therapy
Betof Warner A, Hamid O, Komanduri K, et al. Expert consensus guidelines on management and best practices for tumor-infiltrating lymphocyte cell therapy. J Immunother Cancer. 2024;12(2):e008735. PMID 38423748. https://doi.org/10.1136/jitc-2023-008735
Rohaan MW, Borch TH, van den Berg JH, et al. Tumor-Infiltrating Lymphocyte Therapy or Ipilimumab in Advanced Melanoma. N Engl J Med. 2022;387(23):2113-2125. PMID 36477031. https://doi.org/10.1056/NEJMoa2210233
Sarnaik AA, Hamid O, Khushalani NI, et al. Lifileucel, a Tumor-Infiltrating Lymphocyte Therapy, in Metastatic Melanoma. J Clin Oncol. 2021;39(24):2656-2666. PMID 33979178. https://doi.org/10.1200/JCO.21.00612
Phillips C. First Cancer TIL Therapy Gets FDA Approval for Advanced Melanoma. Cancer Currents Blog, National Cancer Institute. March 5, 2024. https://www.cancer.gov/news-events/cancer-currents-blog/2024/fda-amtagvi-til-therapy-melanoma
Medina T, Chesney JA, Whitman E, et al. 119O Long-term efficacy and patterns of response of lifileucel tumor-infiltrating lymphocyte (TIL) cell therapy in patients with advanced melanoma: A 4-year analysis of the C-144-01 study. Immuno-Oncol Technol. 2023;20:100591. Conference abstract, not indexed in PubMed. https://doi.org/10.1016/j.iotech.2023.100591
Disclaimer
This article is for educational purposes only and does not replace professional medical advice, diagnosis or treatment. Always talk to your doctor or oncologist about your own situation.
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