CALL ME CRAZY but if I have a choice of what kind of illness I should get, I’d choose leukemia. Why? Because leukemia is a sickness of nobility. All those inbreeding has exacted its toll on the poor princes and princesses.
It is also a type of cancer that is difficult to cure. But a type of cancer immunotherapy called CAR-T has revolutionized the treatment of blood cancers, but so far hasn’t been effective in 90% of cancers, like DIPG, that are considered solid tumors. CAR-T, short for chimeric antigen receptor T cells, involves taking immune cells from the patient, modifying them in a lab to attack cancerous cells and then infusing them back into the body.
Scientific theory and a few isolated examples have suggested CAR-T should be able to fight solid tumors. Some trial participants have seen their tumors shrunk by 95% or more – a dramatic achievement never before seen in DIPG. Though some have since died, most survived far longer than expected.
It’s still early days and unclear what success with CAR-Ts might eventually look like, both in DIPG specifically and solid tumors more broadly.
For blood cancers, CAR-T is delivered once, and then the patient’s immune system is left to do the rest of the work. Although the cancers sometimes return, about 70% of advanced chronic lymphocytic leukemia patients respond well to CAR-T, and the approach is also used to treat other types of leukemia, lymphomas and multiple myeloma.
CAR-T researchers have to solve some key challenges to get the therapy to work well against solid tumors. In blood cancers, the targets were relatively clear and found only on cells the body can do without. In solid tumors, it’s tough to identify and destroy cancer cells without also killing off healthy ones.
Another major challenge is keeping the CAR-Ts working long term. The half-life is not too good in solid tumors. Doctors are now giving CAR-T patients additional treatments that stabilize the tumor cells and keep them from changing too much.
In the third major CAR-T trial, they have also added a different kind of immune therapy, known as a checkpoint inhibitor, which lifts a brake cancer puts on the immune system. If there are immune cells ready to fight cancer, this enables them to get to work.
Other cancer researchers now plan to deliver CAR-T directly into the fluid around the brain, hoping to help people with glioblastoma – the aggressive form of brain cancer that claimed the life of Senator Ted Kennedy, among many others. There’s no question CAR-Ts could make a dramatic difference in solid tumors – once they can be made to work. Unlike traditional drugs, CAR-Ts can target and kill cancer cells both in the initial tumor and elsewhere – a living drug that kills and expands and migrates. CAR-T is the only approach that offers the possibility of a long-lasting remission. (By Manny Palomar, PhD, EV Mail July 18-24, 2022 Issue)
