SYDNEY, Dec. 7 (Xinhua) -- Australian researchers on Friday said they have successfully combined two cancer drugs, offering a breakthrough in the treatment of women with metastatic breast cancer.

The move, touted as the first of its kind, involved joining Venetoclax, a drug that has shown promise in the treatment of chronic leukemia, with Tamoxifen, a therapy used to treat breast cancer, according to a statement from The Royal Melbourne Hospital about its researchers' work.

"The primary aim of the study was to determine the safety and tolerability of Venetoclax in combination with Tamoxifen," said the study's principal investigator Professor Geoff Lindeman.

"Venetoclax is a drug that switches off BCL-2, a protein that helps keep cancer cells alive. Our findings suggest that adding Venetoclax to conventional hormone therapy might boost responses," said Lindeman, whose work included collaboration with breast cancer researchers from the Peter MacCallum Cancer Centre. Their findings were published in scientific journal Cancer Discovery.

"Although the study was aimed at determining safety and finding the right dose, we found that 75 percent of the women involved in the study experienced an overall improvement or derived clinical benefit," said Lindeman.

"This result has provided a basis for further studies with Venetoclax, where the hope would be to produce deeper and more durable responses for women affected by breast cancer."

The study was also the first time the leukemia drug has been used on solid tumors; it was not currently approved in breast cancer and further studies would be required to determine its effectiveness, added Lindeman.

"We are excited by the findings and what it could mean for patients with incurable hormone receptor positive breast cancer," he said.