Trial suggests PARP inhibitor drugs may help to prevent ovarian cancer from coming back

In collaboration with Adfero

Treating women with olaparib, a new type of experimental drug called a PARP inhibitor, after their initial cancer treatment, may help prevent their ovarian cancer from coming back, according to a phase-II clinical trial led by UK scientists.

The finding applies to women with the most common form of ovarian cancer - 'high-grade serous' ovarian cancer.

Olaparib, taken in pill form, was designed to target cancers containing faulty BRCA1 and BRCA2 genes, while leaving healthy cells unharmed. But it also appears to be effective in targeting cancers with related genetic defects, which appear to be common in women with high-grade serous ovarian cancer.

An international research team, led by University College London's Professor Jonathan Ledermann, carried out a trial to see whether olaparib could have a role to play in preventing ovarian cancer from coming back in this group of patients.

It is thought that the treatment may help to 'mop up' any cancer cells that are left behind after chemotherapy.

A total of 265 women took part in the trial, all of whom had high-grade serous ovarian cancer and had recently completed a course of platinum-based chemotherapy which had achieved a complete or partial response.

Within eight weeks of finishing their chemotherapy, trial participants started to take olaparib or a placebo (dummy pill).

The researchers found that women who took olaparib had a median of 8.4 months before their cancer came back, compared to 4.8 months for those on the placebo.

Overall survival data are not yet available, as half of olaparib users had not relapsed at the time of data analysis.

Larger clinical trials are now needed but, if the results of this phase-II trial are confirmed in future, maintenance therapy with olaparib could form a new treatment approach to prevent recurrences or prolong remission in women who have recently undergone chemotherapy for ovarian cancer.

Lead author Professor Ledermann, professor of medical oncology at the UCL Cancer Institute and a Cancer Research UK grantee, said: "A well-tolerated anti-tumour agent that could be used for months or perhaps years as maintenance therapy after standard chemotherapy could be a big step forward and ultimately extend survival.

"This study demonstrates proof of principle for the concept of maintenance therapy in ovarian cancer using a PARP inhibitor. Our progression-free survival difference was very impressive and better than we anticipated."

Professor Ledermann carried out this trial with support from AstraZeneca. Cancer Research UK, who did not fund the trial but have played an important role in the development of PARP inhibitors like olaparib, said the results highlighted their potential.

Henry Scowcroft, Cancer Research UK's science information manager, said: "PARP inhibitors were initially designed to treat people whose cancers are caused by rare inherited gene faults. But it's starting to look as though they might be effective in a much wider range of cancers, including this particular type of ovarian cancer.

"Although we need to wait for the long-term results of this trial, it's an important 'proof-of-concept', and hints that there are exciting times ahead for these drugs, which Cancer Research UK played a key role in researching and developing."