Treating cancer using "living drugs"

 
Scanning electron micrograph of a T-cell from healthy individual

Scanning electron micrograph of a T-cell from healthy individual

 

The U.S. Food and Drug Administration (FDA) has recently approved the usage of genetically modified immune cells for treating blood cancer. This marks a historic development in the use of a revolutionary new method for cancer treatment.

The treatment method, known as CAR-T or Chimeric Antigen Receptor T-Cell therapy involves reengineering the immune cells, called T-cells, obtained from the patient’s blood and giving it back after genetic modification. In a sense, patients are given “living drugs”.

 
 

First, the T-cells are collected from a patient’s blood, then they are genetically reengineered to produce a protein called chimeric antigen receptor on their surfaces. These modified T-cells, now called as CAR-T cells, are “empowered" and capable of recognizing target cancer cells expressing a certain antigen.

 
 
While Blood Cells (WBCs) and Red Blood Cells flowing inside the blood streams (animation). T-cells are a type of WBCs and an important component of immune system in human body.
 

The CAR-T cells are then grown in the lab and infused back into the patients. Once in the patient’s bloodstream, these “armed” cells can now identify, and kill the cancer cells that have the antigen on their surfaces.

 
 
 
T-cell killing a cancer cell. The red dye, Propidium Iodide, can only enter living cells once their cell membrane is ruptured. This is an indication that the T-cell is killing the cancer cell.
 

This paradigm of treatment is also called as Cancer Immunotherapy. The approach to cancer treatment is entirely different from conventional approaches, such as chemotherapy. The idea of targeting the immune system itself rather than the tumor, was hailed as a breakthrough.

 
 

The drug approved by FDA Tisagenlecleucel, aka. Kymriah, will be used only for the treatment of patients with a certain type of blood cancer, B-cell precursor acute lymphoblastic leukemia (ALL), and who are less than 25 years in age and unresponsive to conventional therapy or relapsed.

However, CAR-T therapy is also known to be associated with serious side effects sometimes. Cytokine-Release Syndrome (CRS), is one of the frequent and prominent side effects due to the overstimulation of the immune system, in which massive levels of cytokines are released by the CAR-T cells. The symptoms such as high fevers and low blood pressure are generally manageable.

Written by - Alok Jaiswal