In this episode of TechKnow, we look into the science of immunotherapy, which involves tricking the body’s immune system into attacking cancerous tumours. Donated T-cells are given an extra gene to make them target specific leukaemia cells and other genes are disabled to prevent them from attacking their host. We also explore a promising cancer drug called Pembrolizumab. This drug makes the tumour visible to the T-cells.
This new wave of cancer-fighting drugs, called immunotherapy, are the brainchild of Dr James Allison and his partner and wife, Dr Padmanee Sharma, who both work at MD Anderson Cancer Center in Houston, Texas.
“Jim Allison’s breakthrough changed the whole field. What he recognised is the immune system doesn’t just have ‘on’ switches, it has ‘off’ switches. It’s the yin and the yang of the immune system. If you keep trying to turn it on, it has its own internal controls to keep it turned off,” explains Dr Sharma.
“He recognised that if you want the T-cells to really attack cancer, you have to turn off the ‘off’ signal. So you have to block the brakes.”
The human immune system is built around white blood cells, which scientists call T-cells. When a T-cell senses an infection, it will attack. But with many cancers, T-cells will not attack because tumour cells are blocking their attacking mechanism.
Dr Allison’s and Dr Sharma’s immune checkpoint therapy overrides those blocking systems, allowing the T-cells to do their job.
David Wight, who has received treatment for bladder cancer at MD Anderson, is living proof that immunotherapy works. David is in remission, and his life has been extended beyond what anyone imagined.
But according to Dr Sharma, immunotherapy is not for everyone. “Around 20 percent or so do very well … It gives us hope that we can build on this 20 percent to make it 50 percent, 80 percent, maybe 100 percent,” she explains.
Besides checkpoint inhibitor immunotherapy, adoptive cell transfer, known as ACT therapy, is also in the fight against cancer.
With ACT, scientists in the Paris-based lab, Cellectis, are genetically manipulating T-cells and turning them into optimum cancer-killing machines.
In 2015, Dr Andre Choulika’s immunotherapy treatment was tested on its first human subject, Layla Richards, a one-year-old leukaemia patient.
After receiving a single dose of genetically engineered T-cells, Layla went into complete remission within a few weeks.
As of October 2016, Layla Richards remains in remission. A second young patient was also given the T-cell treatment and, while she has not been identified, she is reportedly also in remission.