iStock/Thinkstock(CHICAGO) — A new treatment for ovarian cancer has shown “promising” results in women who are in the advanced stages of the disease, according to the BBC.

The drug, known as ONX-0801, shrunk tumors in more than half the patients who participated in a small trial in London.

The study was backed by the Institute of Cancer Research and the Royal Marsden National Health Service Foundation Trust in the U.K. Researchers had wanted to figure out whether the drug was safe, which is why only a small number of women — 15 — participated.

The drug had significantly shrunk tumors in seven of the patients who carried the specific molecule that the drug was designed to target.

ONX-0801 is the first in a new class of drugs that work by “mimicking the ability of folic acid selectively to latch on to cancer cells,” according to the BBC. Because the drug leaves healthy tissue alone, the side effects often associated with traditional chemotherapy — infections, diarrhea and hair loss — are reduced.

However, the drug has not been proven to extend the longevity of a patient.

“It’s encouraging to see this new drug is showing promise as a potential new treatment for ovarian cancer,” Catherine Pickworth, a spokesperson for Cancer Research UK, told the BBC. “The next steps will be for researchers to test the drug in larger clinical trials to confirm it works and is safe, and to work out which women with ovarian cancer this drug could help.”

The results of the trial were presented at the annual meeting of the American Society of Clinical Oncology in Chicago on Saturday.

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