Drug Combination Overcomes Breast Cancer Treatment Resistance

Suppression of Wnt signaling pathway shows promise.

A new combination of drugs was found to overcome breast cancer treatment resistance during a recent study.

The study, presented at the annual American Association of Cancer Research conference, found in the most common type of breast cancer, the drug Sulforadex was able to break through the treatment resistance that is common in hormonal treatments by attacking cancer stem cells.

Despite the fact that many patients respond well initially to hormonal treatment with drugs such as tamoxifen, many others eventually develop resistance and disease relapse. Prior research has indicated that this resistance occurs due to activation of the Wnt signaling pathway, which is a gene that fuels tumor growth.

Approximately 70% of breast cancers express the estrogen receptor (ER) where standard treatments seek to decrease estrogen levels or block ER function. In the current study, investigators found cancer stem cells that cause tumors to regrow and spread do not express the ER, which indicates these stem cells are not inhibited by standard treatments.

The new therapy combined the Wnt pathway-suppressing drug Sulforadex with standard hormonal treatments, which simultaneously attacks estrogen-sensitive cells and the remaining cancer stem cells.

"The hormonal therapies we use today are very good at treating breast cancer tumors driven by estrogen,” researcher Robert Clarke, MD, said in a press release. "However, they don't completely solve the problem. This combination of drugs potentially allows us to target estrogen-sensitive cells, whilst also mopping up the cells which cause treatment resistance."

Within the next few months, the researchers hope to recruit patients for the launch of a clinical trial.

"We are really excited about the data presented at the AACR. Dr Rob Clarke and his excellent research team have demonstrated the efficacy of Sulforadex in patient derived cancer tissues in vitro and, importantly, in an in vivo setting,” said David Howat, MD, head of Research and Development at Evgen Pharma, in a press release. "We now intend to extend this collaboration and advance Sulforadex into a clinical trial with breast cancer patients."