Your Health Matters


Experimental cancer treatment uses genetic modification

Therapy utlizes a "living drug"
Cancer (FILE)
Posted at 11:30 AM, Feb 10, 2022
and last updated 2022-02-10 14:30:28-05

(KERO) — Genetic modification is not a new concept. Imagine if doctors were able to modify human cells to become cancer killers.

In 2010 two men with a form of blood cancer agreed to be part of an experimental treatment. Now more than a decade later doctors are considering them cured. they stayed cancer free. The findings were just published in the journal Nature.

Compared to chemotherapy researchers say this treatment is far less harmful and only requires one dose to last a lifetime.

"Cells expand in patient and persist in patient, and those are critical elements of this therapy," explained Jos Melenhorst, a research professor a the University of Pennsylvania. "So it's some call it a living drug because essentially that's what it is. Whereas chemotherapy it's infused, washes out. And may actually also cause secondary malignancy so itself can be damaging, cause other cancers."

Melenhorst said ‘cytokine release syndrome’ was the only major side effect to the CAR-T cells. That's common for immunotherapy treatments.

Cytokines are proteins in the body that signal an immune response. The modified CAR-T cells rely on them to help attack a tumor. That was the case with the two patients in this study.

Because of their success with the treatment researchers have started additional clinical trials and infused about 50 more cancer patients with CAR-T cells.

23ABC In-Depth

A "Living Drug"

CAR T cells are the equivalent of "giving patients a living drug," explained Renier J. Brentjens, M.D., Ph.D., of Memorial Sloan Kettering Cancer Center in New York, another early leader in the CAR T-cell field.

As its name implies, the backbone of CAR T-cell therapy is T cells, which are often called the workhorses of the immune system because of their critical role in orchestrating the immune response and killing cells infected by pathogens. The therapy requires drawing blood from patients and separating out the T cells. Next, using a disarmed virus, the T cells are genetically engineered to produce receptors on their surface called chimeric antigen receptors, or CARs.

These receptors are "synthetic molecules, they don't exist naturally," explained Carl June, M.D., of the University of Pennsylvania Abramson Cancer Center, during a recent presentation on CAR T cells at the National Institutes of Health campus. Dr. June has led a series of CAR T cell clinical trials, largely in patients with leukemia.

These special receptors allow the T cells to recognize and attach to a specific protein, or antigen, on tumor cells. The CAR T cell therapies furthest along in development target an antigen found on B cells called CD19 (see the box below, titled "The Making of a CAR T Cell").

Once the collected T cells have been engineered to express the antigen-specific CAR, they are "expanded" in the laboratory into the hundreds of millions.

The final step is the infusion of the CAR T cells into the patient (which is preceded by a "lymphodepleting" chemotherapy regimen). If all goes as planned, the engineered cells further multiply in the patient's body and, with guidance from their engineered receptor, recognize and kill cancer cells that harbor the antigen on their surfaces.

- National Cancer Institute