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The New Cancer Treatments: Immunotherapies
By Dr Stewart Fleishman on March 31, 2016
By Dr Stewart Fleishman on March 31, 2016
Significant progress has been made in cancer treatment, especially in ways that help our own immune system already active in our bodies, fight off cancer. The progress has come in spurts. With the newer immunologic treatments, there has been amazing progress for certain types of cancers, or for individuals whose cancer has a genetic profile that can respond to a novel treatment. Sometimes, reports of “major breakthroughs” do not seem to live up to the implied promise of a significant advantage for each of us with cancer of various types and at various stages. We often become jaded with each passing news story in the print or electronic media reporting on the latest findings. Beyond the hype, some advances for some people are here, now.
“We often become jaded with each passing news story
in the print or electronic media reporting on the latest
findings. Beyond the hype, some advances for some
people are here, now.”
Our immune systems usually act efficiently to protect us against outside substances that the body recognizes as “not us”. It could be a virus, a bacterium, a fungus or a cancer cell though born from our own cells has undergone a genetic change. Somehow, in ways we don’t yet fully understand, our normal cells become cancer when they undergo some change in its genetic information inside of the cells or in the proteins that coat the outside of our cells. This change can overhaul or inactivate our natural resistance or immunity. The newest treatments in cancer, when matched properly to certain types of cancers can inactivate the cells so that they cannot reproduce into more and more cancer cells. Or they may reinforce our natural immune response to help it destroy the “foreign” substance or cells.
“The newest treatments in cancer, when matched properly
to certain types of cancers can inactivate the cells so that
they cannot reproduce into more and more cancer cells.
Or they may reinforce our natural immune response to help
it destroy the “foreign” substance or cells.”
As a number of these chemical compounds are in various stages of development, we are just learning about their power and limitations. Some provide an overall boost to our natural immunity. Others act like vaccinations that expose our natural immunity to a less-threatening substance that starts our immune systems to attack cancer cells trying to multiply. Still others can fortify the immune system by releasing the body’s control over them so they can fight back against the outside substances or cells. And still others are man-made proteins that can block outside proteins or cells by overwhelming them with a lot of a single antibody that is surrounds the growing cancer cells. Still others form a cell like a key that fits so perfectly inside its matching lock to prevent it from fitting into similarly shaped locks on the cancer cells themselves.
Likewise, there are advances in the development of vaccines, acting like other vaccinations for the flu or pneumonia. A purified version of a cancer cells that cannot themselves grow can stimulate the body’s response against its naturally occurring form – the cancer cells that are similar to it. Sipuleucel-T (Provenge®) is currently licensed to treat advanced prostate cancer. A tuberculosis vaccine commonly used in other countries in the recent past (BCG: Bacile Calmette-Guerin) has been shown to unleash an immune response in bladder cancer when put into the bladder with a catheter or injected into a skin melanoma.
An even more novel group of immunotherapies, immune checkpoint inhibitors, work through a different yet eloquent system. When working properly, our immune system cells are kept from attacking our healthy tissues at immune checkpoints named for their comparison to customs or security checkpoints. One could imagine that our natural immunity could likewise be stopped from getting to cancer cells as they recognize and stay away from our healthy cells when detained at the checkpoint. Working around this mechanism, both nivolumab (Opdivo®) and pembrolizumab (Keytruda®) have approval for use in lung cancer and melanoma.
Perhaps the major advance that has occurred with these new classes of immunotherapies shifts how we think about treating cancers overall, generating much of the excitement. As the immunotherapies target certain proteins on a cell surface or genes, creatively investigators have used them in cancers of a different type than those where they proved effective but share that certain protein or gene. This shift in thinking potentially widens the choices of treatments for a particular kind of cancer to a treatment useful in a different kind of cancer as long as the protein or gene are shared. That change in thought opens up many new avenues of research study and has earned the name of targeted medicine or precision medicine.
“This shift in thinking potentially widens the choices of treatments
for a particular kind of cancer to a treatment useful in a different
kind of cancer as long as the protein or gene are shared. That change
in thought opens up many new avenues of research study and has
earned the name of targeted medicine or precision medicine.”
For those of your that are interested in the more technical aspects of the different drugs read below:
Other newer treatments are in the drug development pipeline.