FDA Approval: Tisagenlecleucel (Kymriah) for Leukemia

What was cleared, and for whom

On August 30, 2017, the FDA approved tisagenlecleucel, sold as Kymriah. It was the first therapy of its kind cleared anywhere in the United States: a treatment made from a patient's own genetically edited immune cells.

The approved group was narrow. NCI describes it as people up to 25 years of age with B-cell acute lymphoblastic leukemia that does not respond to treatment, or that has come back two or more times.

Every word there does work. Not all leukemia. Not adults over 25. Not a first course of treatment. Whether any individual fits the label is a decision for their treating team.

The leukemia in question

Acute lymphoblastic leukemia, or ALL, starts in the bone marrow. Immature white blood cells multiply before they finish developing and crowd out healthy blood cells. "Acute" means it moves fast, over weeks rather than years.

Most childhood ALL begins in B cells, the white blood cells that normally make antibodies. SEER records about 1.9 new ALL cases per 100,000 people per year, and the median age at diagnosis is 18. Leukemia is the most common cancer of childhood.

Why a new option was needed

Standard treatment already works well. NCI reports that about 85% of patients aged 1 to 18 with newly diagnosed ALL are expected to be long-term event-free survivors on current regimens, with more than 90% alive at five years. Treatment runs two to three years, in phases, and includes drugs delivered into the spinal fluid because ordinary chemotherapy does not reach the brain well.

The problem is the remainder. When ALL never goes into remission, or returns twice, the options thin out fast. That is the gap this approval addressed. Our leukemia overview covers the standard phases in more detail.

How the treatment is made

The process is closer to manufacturing than to prescribing.

1. T cells — the immune system's attack cells — are separated out of the patient's blood.
2. The cells are shipped to a processing plant.
3. A gene is added so each cell grows a chimeric antigen receptor on its surface. That receptor grips CD19, a protein sitting on B cells, healthy and cancerous alike.
4. The edited cells are multiplied into hundreds of millions and shipped back.
5. The patient has lymphodepleting chemotherapy to clear space, then receives one infusion.

NCI puts the round trip at roughly 22 days. Because the cells keep dividing inside the body, one infusion is the whole course. Our page on immunotherapy sets this alongside the other ways treatment can use the immune system.

The evidence behind the decision

FDA based the approval on a multicenter trial of 63 children and young adults whose B-cell ALL had relapsed or resisted treatment. Within three months, 83% went into remission, according to NCI.

The wider ELIANA trial results were published in the New England Journal of Medicine in 2018. Among 75 patients who were infused and could be assessed:

• 81% went into remission within three months.
• Everyone who responded tested negative for minimal residual disease, meaning no leukemia cells were detectable even by sensitive flow cytometry.
• Overall survival was 90% at 6 months and 76% at 12 months.
• Event-free survival was 73% at 6 months and 50% at 12 months.
• The engineered cells were still detectable in blood as long as 20 months later.

The boxed warning

A boxed warning is the strongest caution the FDA puts on a label. Kymriah carries one, and the trial numbers show why.

Cytokine release syndrome occurred in 77% of ELIANA patients. The activated cells release a surge of signaling proteins; fever comes first, and blood pressure, breathing, and kidney function can follow. Just under half of patients needed tocilizumab, an arthritis drug that blocks one of those signals.

Neurologic events occurred in 40%. These included confusion and seizures. No cerebral edema — dangerous brain swelling — was reported in that study. Grade 3 or 4 side effects thought to be treatment-related affected 73% of patients.

This is why the therapy is given only at certified centers with intensive care on hand.

Survival, in group terms

SEER reports that 73.2% of people diagnosed with ALL between 2016 and 2022 were alive five years later. About 126,118 people in the United States were living with ALL in 2023.

That 73.2% covers every age, every subtype, and every treatment era in the window. It is a statement about a population. It is not a forecast for any one person reading it.

Signs that should prompt a blood test

ALL symptoms come from failing blood counts, and they build over weeks. See a clinician if a child or young adult has:

• Bruises or pinpoint red spots appearing without injury.
• Nosebleeds or gum bleeding that will not stop.
• Fevers that keep returning, or infections that keep coming back.
• Deep fatigue and pallor that do not improve with rest.
• Bone or joint pain, often in the legs, sometimes with a limp or refusal to walk.
• Lumps in the neck, armpit, or groin, or a swollen belly.

A complete blood count is a quick, cheap first test and it usually points the way.

What this approval cannot tell you

• An approval defines eligibility in general terms. It does not say whether the treatment suits one particular person.
• Approval means the evidence met the regulator's bar for this use. It is not a promise of benefit.
• The pivotal trial had one arm and 63 patients, with no comparison group and no long-term follow-up at the time of approval.
• Cost, travel to a certified center, and weeks of close monitoring are real barriers this page cannot resolve.
• Labels change. Indications, warnings, and age limits are all revised as more data arrive, so check the current label rather than a 2017 summary.

Sources

This article was written from the sources below, which were checked on the source-check date shown above.

• U.S. Food and Drug Administration, KYMRIAH product page: https://www.fda.gov/vaccines-blood-biologics/cellular-gene-therapy-products/kymriah
• National Cancer Institute, Cancer Currents, "CAR T-Cell Therapy Approved for Some Children and Young Adults with Leukemia," September 11, 2017: https://www.cancer.gov/news-events/cancer-currents-blog/2017/tisagenlecleucel-fda-childhood-leukemia
• Maude SL and colleagues, "Tisagenlecleucel in Children and Young Adults with B-Cell Lymphoblastic Leukemia," New England Journal of Medicine, 2018 (PMID 29385370): https://pubmed.ncbi.nlm.nih.gov/29385370/
• SEER Cancer Stat Facts, Acute Lymphocytic Leukemia: https://seer.cancer.gov/statfacts/html/alyl.html
• National Cancer Institute, Childhood Acute Lymphoblastic Leukemia Treatment (PDQ) — Health Professional Version: https://www.cancer.gov/types/leukemia/hp/child-all-treatment-pdq

How this page was made

An AI-assisted editorial system helped prepare this page. No named medical reviewer has reviewed it unless one is listed.

The National Cancer Information Foundation publishes Cancer Explained. It is not a diagnostic service, does not recommend treatments, and is not for emergencies.

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