Study finds way to kill chemo-resistant ovarian cancer cells

A new study on ovarian cancer by scientists from Ottawa and Taiwan may spark a whole new avenue of research on why some patients' tumours are resistant to chemotherapy and ways to overcome it.

Ovarian cancer is the most deadly gynecological cancer, taking the lives of more than 50 per cent of women who are diagnosed with the disease, said Ben Tsang, senior scientist at the Ottawa Hospital Research Institute and one of the researchers behind the new study. 

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But one of the main hurdles in treating the cancer has been the resistance of some patients' tumours to chemotherapy.

“There’s no point in treating the patient with chemo if they’re going to be resistant to it,” Tsang said.

The work Tsang contributed to — published in this week's Proceedings of the National Academy of Sciences — suggests there might be a way to test for resistance, and ultimately to overcome it.

“We don’t always know the cause of chemo resistance. This study gives us a clue,” said Barbara Vanderhyden, a professor at the University of Ottawa specializing in ovarian cancer.

The study looked at the role of a protein called gelsolin in resistance to anti-cancer medications.

“We found that an increased level of this protein in cancer cells makes a difference to how well a patient responds to chemotherapy,” Tsang said.

In the study, patients with high levels of gelsolin had a shorter lifespan than those with lower levels. The research found that gelsolin works at a molecular level to shield cancer cells against a widely used chemotherapy drug called cisplatin.

How to kill chemo-resistant cells

The findings not only open a door to determining who may be resistant but also to overcoming it.

“The same protein that makes ovarian cancer cells resistant to chemo can be used to make the cells become respondent,” Tsang explained.

The research showed that by cutting down gelsolin to a fragment and re-introducing it into the chemo-resistant cancer cells, scientists could make the cells susceptible to the cancer-killing effects of cisplatin. 

However, Tsang cautioned that a great deal more work has to be done before these findings can benefit women diagnosed with ovarian cancer.

“Even when we have a fragment, we have to devise a good way to deliver it,” said Tsang, who added that possible partnerships and funding from industry partners will be the deciding factor in the development of his work. 

Typically, findings such as this can take anywhere from five to ten years to go from the research phase to the development phase.

Next best thing to a cure

Research on chemo drug resistance is important because next to finding a cure to ovarian cancer, understanding why available treatments don't always work is the only way to save more lives of those who have it. 

“What we’re looking for in the absence of a cure is the availability to use different chemo therapeutics,” said Anne-Marie Mes-Masson, scientific director of the Montreal Cancer Institute. 

Mes-Masson said knowing which patients may be resistant to certain chemotherapy treatments may be a significant step in where ovarian cancer research goes next.

“It is an important contribution to the field,” Mes-Masson said, “This will spark a whole new avenue of research. It’s going to lead people to investigate if this will be a new therapeutic target.” 

However, Mes-Masson added that the new study only explains one type of chemo resistance, leaving many more questions unanswered.

The Canadian Cancer Society estimates that this year, 2,700 Canadian women will be diagnosed with ovarian cancer and 1,750 women will die from the disease. 

Based on 2009 estimates, about 1 in 72 Canadian women is expected to develop ovarian cancer during her lifetime and 1 in 93 will die from it.