Personalized Immunotherapy Could Treat Metastatic Breast Cancer

Personalized immunotherapy from an individual’s tumor-fighting immune cells could potentially treat metastatic breast cancer, according to a study from the National Cancer Institute’s Center for Cancer Research.

The ongoing Phase 2 study used whole-genome sequencing to identify mutations in tumor samples in 42 women with metastatic breast cancer whose cancers had progressed despite previous treatments. The trial uncovered whether an immunotherapy approach could lead to tumor regressions in individuals with metastatic epithelial cancers, including breast cancer. 

Many individuals with metastatic breast cancer can mount an immune reaction against their tumors. The study found a prerequisite for this type of immunotherapy called tumor-infiltrating lymphocytes (TILs).

Researchers separated TILs from the tumor samples and tested their reactivity against neoantigens produced by different mutations in the tumor. In the trial, about 67 percent of women generated an immune reaction against their cancer.

Additionally, six women were treated, half of whom experienced measurable tumor shrinkage. One woman remains cancer-free today, while the other two women had tumor shrinkage of 52 percent and 69 percent after 6 months and 10 months, respectively.

And of the women whose disease returned and then surgically removed, none has evidence of cancer nearly five years and 3.5 years, respectively, after their TIL treatment.

“It’s popular dogma that hormone receptor-positive breast cancers are not capable of provoking an immune response and are not susceptible to immunotherapy,” Steven A. Rosenberg, MD, PhD, chief of the surgery branch in NCI’s Center for Cancer Research and study leader, said in the study.

“The findings suggest that this form of immunotherapy can be used to treat some people with metastatic breast cancer who have exhausted all other treatment options,” Rosenberg continued.

Immunotherapy can help an individual’s immune system fight cancer. But most available immunotherapies have shown limited effectiveness against hormone receptor-positive breast cancers.

In the 1980s, Rosenberg initiated the first trial that used an immunotherapy approach. With the opening of NCI’s new building devoted to cell-based therapies, he and his colleagues can begin treating more individuals with metastatic breast cancer as part of the ongoing clinical trial.

Rosenberg noted that this new immunotherapy approach could potentially treat individuals with other types of cancer as well.