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What Is CAR-T Cell Therapy?


This past summer, the FDA made the landmark decision to approve CAR-T cell therapy, a type of immunotherapy, created here at Penn Medicine. This personalized cellular therapy genetically alters a patient’s immune cells and trains them to recognize and destroy their cancer.

The first CAR-T cell therapy was approved in patients up to 25 years old who have acute lymphoblastic leukemia (ALL) that is either relapsing (went into remission, then came back) or refractory (did not respond to previous treatments). A second CAR-T cell therapy was approved in October for adult patients with relapsed or refractory diffuse large B-cell lymphoma, transformed follicular lymphoma and primary mediastinal B-cell lymphoma (all subtypes of non-Hodgkin’s lymphoma).

But how exactly does this therapy turn the body into a cancer fighter? We break it down into two parts: firstly, what happens outside of the body, and secondly, what happens inside of the body.

How CAR-T Works Outside the Body

T cells, a type of white blood cell, are important because they help the body fight infection. T cells can also kill cancer cells. However, cancer can disguise itself as part of the body; therefore, making it difficult for the T cells to recognize and fight the disease on its own. That’s why the first step of CAR-T cell therapy involves extracting T cells from a patient’s blood, a process known as leukapheresis, which is similar to the process of dialysis.

Through leukapheresis, blood is removed through an intravenous tube and passed through a machine to separate the patient’s T cells. The remaining blood cells are returned to the body through another tube. Once collected, the T cells are sent to a specialized lab to be re-engineered with CARs (chimeric antigen receptors).

CARs are essential to the T-cell therapy as they are man-made molecules genetically designed to target a protein or molecule on the surface of the patient’s cancer cell.

Infographic of Penn's personalized CAR T-cell therapy

How CAR-T Works Inside the Body

As soon as the new T cells receive the CAR gene, they are infused back into the patient’s body and the real work can begin. The T cells immediately begin to search for cancerous tumor cells to target. The CAR from the T cells then binds to the protein on the surface of the tumor cell and attacks.

Each modified T cell has the capacity to produce more than 10,000 new cells, which work together to target and kill each and every cancer cell, allowing the body to recover and become healthy once again.

A Look into the Future of Immunotherapy

As pioneers in immunotherapy, we've forged the way with key advances, and our discoveries continue to drive progress. Every day, our doctors and scientists are hard at work, exploring and testing new ways to use the immune system to fight cancer.

Penn’s success with CAR-T cell therapy has paved the way for FDA approval of this new therapy.

Although these are the only two CAR-T cell therapies currently approved by the FDA, many are being tested in clinical trials, particularly in other blood cancers and solid tumors.

Beyond cancer, this approach of utilizing the immune system to fight disease has encouraged other doctors and scientists to test similar treatments in inherited blindness, diabetes, cardiology, organ rejection, and Parkinson’s.

We can’t yet declare victory over cancer and these diseases, but we can say: There’s hope.

About This Blog

The Focus on Cancer blog discusses a variety of cancer-related topics, including treatment advances, research efforts and clinical trials, nutrition, support groups, survivorship and patient stories.

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