Immunotherapy is revolutionizing the way doctors treat cancer. But it doesn’t work for everyone or for every type of cancer. What makes it a lifesaver for some people and completely ineffective for others? It all depends on the cancer — and on other factors that researchers are still trying to figure out.
“Immunotherapy is a complete change from the standard treatments we’ve used for cancer for a long time,” says oncologist Nathan Pennell, MD.
Traditional treatments target the cancer and try to kill it, or at least stop it from growing. Immunotherapy drugs work differently. They unblock your immune system so that it can target and destroy the cancer.
Immunotherapy can cause cancer to go into remission and, in rare cases, might even cure people who previously might have been incurable, Dr. Pennell says.
The main drawback is that it doesn’t work for every patient or every type of cancer. And, determining who will benefit isn’t an exact science.
Cancers that doctors commonly treat with immunotherapy include:
These are some of the most common cancers, which is why researchers have tested immunotherapy on them. Dr. Pennell predicts that eventually researchers will test it for treating all types of cancer.
Even among patients who have cancers that are known to respond, though, it’s hard to predict who will benefit.
“We’re not yet perfect at picking out who will benefit the most,” he says. “But we do have some tools to help us decide.”
For example, doctors now routinely test patients who have non-small-cell lung cancer for a type of protein called PD-L1. Those with cancer containing high levels of PD-L1 tend to respond better to immunotherapy, he says.
One recent study showed that for these patients, immunotherapy significantly improved survival rates. It affected both how much the cancer shrank and how long it stayed under control.
“On average, these patients are now living about two and a half years, whereas with chemotherapy alone they tend to live about a year,” Dr. Pennell says.
For some patients, the benefits are even greater.
About 15 to 20 percent of lung cancer patients taking immunotherapy drugs continue to respond as long as they’re on them — sometimes for longer than five years. For a small number of patients, the treatment may cure the cancer entirely.
Genetic testing also helps doctors determine who will respond well.
“We look at what’s called the tumor mutation burden,” Dr. Pennell says. By sequencing the DNA of the tumor, doctors determine whether the cancer contains a high level of mutated genetic material. If so, it’s more likely to respond, because it’s easier for the immune system to recognize and attack these tumors.
For some types of cancer, including melanoma and lung cancer with high PD-LI, immunotherapy is now the standard of care. That means it is likely one of the first-line treatments you’ll receive.
For other cancers, doctors may try immunotherapy after chemotherapy stops working. Talk to your care team to find out whether it could help treat your cancer.
You may also consider joining a clinical trial.
“There are a lot of clinical trials happening that are combining immunotherapy with chemotherapy, radiation, other types of immune therapies like vaccines,” says Dr. Pennell. “Hopefully through this research, we’ll be able to expand the number of people who benefit from immunotherapy.”