Researchers have discovered that two drugs might be better than one for women who have advanced endometrial cancer.
Combining chemotherapy and immunotherapy or a monoclonal antibody at the same time helped these patients live longer without their cancer progressing, especially those who had a specific type of endometrial cancer known as a mismatch repair-deficient tumor.
"We found a profound improvement," Dr. Carol Aghajanian, a medical oncologist specializing in gynecologic cancers at Memorial Sloan Kettering Cancer Center in New York City, who was senior study author on one of the reports, told NBC News.
The findings from the two studies were published March 27 in the New England Journal of Medicine and simultaneously presented at the annual meeting of the Society of Gynecologic Oncology in Tampa, Fla.
"This is going to drastically change the conversation" with patients -- "probably as of tomorrow," Dr. David O'Malley, a gynecologic oncologist with The Ohio State University Comprehensive Cancer Center, told NBC News.
Chemotherapy is typically used to treat women with this cancer, and immunotherapy is only approved as a second-line treatment.
But in one study, researchers led by Aghajanian found that adding the immunotherapy drug pembrolizumab (Keytruda) to a standard chemotherapy regimen of carboplatin and paclitaxel cut the risk of advanced or recurrent cancer returning by up to 70%.
The improvement was an average of 13.1 months before the disease progressed in women who received the combination treatment, compared to 8.7 months for those on chemotherapy alone.
In women who had a mismatch repair-deficient tumor, those in the chemo-only group averaged 7.6 months before their cancer progressed, while those who got chemo plus immunotherapy were doing so well a year later that not enough showed tumor progression for researchers to determine how long the additional benefits might last.
"Patients with either advanced or recurrent endometrial cancer don't have a lot of great treatment opportunities," Dr. Pamela Soliman, a gynecologic oncologist at MD Anderson Cancer Center in Houston who was not involved in the new studies, told NBC News. "This is really practice-changing."
Regulators are now reviewing the new data, Aghajanian said. The U.S. Food and Drug Administration would need to change its guidance on immunotherapy before it could be widely used to treat late-stage endometrial cancer, NBC News reported.
In the second study, researchers combined chemotherapy with a monoclonal antibody called dostarlimab (Jemperli). Compared to women treated with chemotherapy alone, that treatment reduced cancer's return by up to 61% for up to two years, depending on tumor type.
About 66,200 cases of endometrial cancer will be diagnosed this year in the United States, according to the American Cancer Society. And more than 13,000 women will die of the disease.
The cancer is typically detected after symptoms begin (such as irregular vaginal bleeding) because women are not screened for the disease.
The rate of new endometrial cancer is growing about 0.6% annually, according to the U.S. National Cancer Institute.
"Endometrial cancer is one of the few cancers that is rising, increasing in mortality in the United States," said Aghajanian. "Unfortunately, very few treatments have been developed specifically for it."
More information
The American Cancer Society has more on endometrial cancer.
SOURCE: NBC News