WEDNESDAY, Feb. 9, 2022 (HealthDay News) — An experimental therapy that harnesses the body’s tumor-fighting immune cells may be effective for some women with advanced breast cancerearly research suggests.
The findings come from an ongoing trial at the US National Cancer Institute (NCI). It is testing a new approach to treat women whose breast cancer has spread throughout the body and is not responding to standard therapies.
At this point, the team reports only six women who have undergone the immunotherapy. Three responded and have been cancer-free for at least 3.5 years, according to findings published online Feb. 1 in the Journal of Clinical Oncology.
“This is highly experimental and not yet approved by the Food and Drug Administration,” said lead researcher Dr. Steven Rosenberg, chief of the surgery branch at the NCI Center for Cancer Research.
But, he said, the initial findings offer “hope.”
Rosenberg said the results also run counter to the traditional “dogma” that breast cancer does not usually elicit a large immune response and therefore is generally not amenable to immunotherapy.
Immunotherapy refers to any treatment that uses the defenses of the immune system to fight a disease. There are several forms of cancer immunotherapy already approved, but not all types of cancer respond well to these drugs.
Melanoma it’s an excellent example of a cancer that responds well, Rosenberg said. Melanoma Tumors carry many mutations, which can generate a strong immune reaction. Y immunotherapy (particularly drugs called checkpoint inhibitors) has transformed the treatment of advanced melanoma.
In contrast, breast tumors contain relatively few mutations, and so far there has been limited success in treating advanced breast cancer with available immunotherapies. Checkpoint inhibitors are approved for certain women with aggressive subtype of breast cancer known as triple negative.
The approach being developed by the Rosenberg team is different. “We’re using the patient’s T cells as a drug,” she said.
Until now, researchers have used the approach to treat patients with advanced melanoma and other types of cancer, including a rare gastrointestinal cancer.
Specifically, the treatment relies on tumor-infiltrating lymphocytes, T cells found in and around a tumor. The idea is that if those T cells are really reactive against the tumor, that can be enhanced and used as a weapon.
The current study involved 42 women with metastatic breast cancer that did not respond to conventional treatments. Metastatic means that your cancer had spread. Each patient underwent surgery to remove a sample of the tumor, which the researchers genetically sequenced to identify its mutations.
They then isolated the T cells from the tumor and, in the laboratory, tested the cells’ reactivity to tumor-specific mutations.
It turned out that in the majority of patients (67%) these T cells were reactive to at least one of their tumor mutations.
Why weren’t those T cells killing the tumor?
The problem, as Rosenberg explained, is that tumors have tricks to evade the immune response. So those tumor-infiltrating T cells alone weren’t enough.
The tactic of immunotherapy seeks to help. The patient’s reactive T cells are multiplied in the laboratory to form an army, then infused back into the body to seek out and destroy tumor cells.
Of the women in this trial, six were able to undergo the treatment, which also involved four doses of the checkpoint inhibitor Keytruda (pembrolizumab). That was given before the infusion, to prevent the newly introduced T cells from being inactivated.
Of those six patients, three saw their tumors shrink. One woman had a complete response and remains cancer free after more than 5.5 years. The other two patients had a partial response, then underwent surgery when new tumor growth was found.
Both are now cancer-free 5 and 3.5 years, respectively, after receiving immunotherapy.
“What we’re doing is creating a unique drug for each patient,” Rosenberg said. “That’s a new concept.”
Dr. Erica Mayer is an American Society of Clinical Oncology Fellow and an Institute Physician at the Dana-Farber Cancer Institute in Boston.
“These are very positive signs,” he said of the results for the three patients.
Still, Mayer cautioned, much more remains to be learned about the long-term effectiveness and safety of immunotherapy. Beyond that, he said, there will be questions about how to translate such a complex treatment into the real world.
“Is this something that could be done outside of specialized centers?” Mayer said.
He also noted that several immunotherapy approaches for breast cancer are being studied, including combining immunotherapy drugs with other treatments, such as “targeted” drugs.
“Our progress depends on ongoing clinical trials and patient participation in them,” Mayer said.
The US National Cancer Institute has more about breast cancer treatment.
SOURCES: Steven Rosenberg, MD, chief, surgery branch, Cancer Research Center, US National Cancer Institute, Bethesda, Md.; Erica Mayer, MD, MPH, Institute Physician, Dana-Farber Cancer Institute, Boston, and Volunteer Expert, American Society of Clinical Oncology, Alexandria, Va.; Journal of Clinical Oncology, February 1, 2022, online