Ovarian cancer is the fifth most common cancer affecting women in the UK, and 6,500 women are diagnosed every year. Cisplatin is commonly used to treat ovarian cancer, but it is associated with side effects in some people, and some types of this cancer are resistant to cisplatin treatment. There is thus a pressing need for the development of new drugs that are effective against ovarian cancer in people who are less responsive to cisplatin.

The novel anti-cancer drug Diindolylmethane (DIM) has previously been shown to prevent the growth of ovarian cancer cells, without affecting normal cells. In a new study published by BMC Medicine, Kandala and Srivastava shed light on the mechanism by which DIM affects ovarian cancer cells. The authors show that DIM works by blocking production of the transcription factor STAT3, whose normal role is in cell growth and division. STAT3 is present at abnormally high levels in many types of cancer, and has been implicated in cisplatin resistance. They found that DIM blocks STAT3 activation by the immune system messenger interleukin 6 (IL-6), and also reduces the amount of IL-6 in ovarian cancer cells.

Importantly, Kandala and Srivastava also showed that DIM enhanced the anti-cancer effects of cisplatin in both human ovarian cancer cells and in mice, where a combination of both drugs reduced tumour growth by an extra 50% compared with cisplatin alone. DIM is an exciting potential future therapy for ovarian cancer, which could overcome the problems with cisplatin resistance in some women.