Drug to curb female infertility from cancer treatments found

Scientists have identified a drug that may protect women from life-altering infertility that commonly follows cancer treatments.
Women who are treated for cancer with radiation or certain chemotherapy drugs are commonly rendered sterile.
According to a previous study, nearly 40 per cent of all female breast cancer survivors experience premature ovarian failure, in which they lose normal function of their ovaries and often become infertile.
Women are born with a lifetime reserve of oocytes, or immature eggs, but those oocytes are among the most sensitive cells in the body and may be wiped out by such cancer treatments.
The study, published in the journal Genetics, builds on previous research that identified a checkpoint protein (CHK2) that becomes activated when oocytes are damaged by radiation.

CHK2 functions in a pathway that eliminates oocytes with DNA damage, a natural function to protect against giving birth to offspring bearing new mutations.

When the researchers irradiated mice lacking the CHK2 gene, the oocytes survived, eventually repaired the DNA damage, and the mice gave birth to healthy pups.
The new study explored whether the checkpoint 2 pathway could be chemically inhibited.
"It turns out there were pre-existing CHK2 inhibitor drugs that were developed, ironically enough, for cancer treatment, but they turned out not to be very useful for treating cancer," said John Schimenti, from Cornell University in the US.

"By giving mice the inhibitor drug, a small molecule, it essentially mimicked the knockout of the checkpoint gene," said Schimenti.
When doctors recognize the need for oocyte-damaging cancer treatments, women may have their oocytes or even ovarian tissue removed and frozen, but this practice delays treatment.
Also, when women run out of oocytes, women's bodies naturally undergo menopause, as their hormonal systems shift.
"That is a serious dilemma and emotional issue when you layer a cancer diagnosis on top of the prospect of having permanent life-altering effects as a result of chemotherapy, and must face the urgent decision of delaying treatment to freeze oocytes at the risk of one's own life," said Schimenti.

The study sets a precedent for co-administering this or related drugs and starting cancer therapy simultaneously, though such interventions would first require human trials.