A chemo/targeted drug combination being trialed by UK researchers has shown promise in patients with advanced ovarian or lung cancer in whom all other treatments have failed.

In the study, led by a team at The Institute of Cancer Research, London, and The Royal Marsden NHS Foundation Trust, the combination of vistusertib and paclitaxel caused tumours of over half of patients with ovarian cancer and over a third with lung cancer to shrink, and stopped patients’ cancers from growing for nearly six months.

“This far exceeds what is expected with standard treatments in patients with advanced disease who have already had, and have now become resistant to, standard treatment,” according to an ICR press release.

The researchers initially tested if the combination was safe, and found it to be well tolerated with manageable side-effects.

But the study also looked at its effectiveness, and found that 52 percent of the ovarian cancer patients and 35 percent of the lung cancer patients had a reduction of at least 30 percent in the size of their tumours.

Furthermore, for each of these cancer types - which had become resistant to all other types of available treatment, including chemotherapy - the combination stopped cancers growing for an average of 5.8 months.

Earlier research by the ICR found that chemotherapy-resistant ovarian cancers typically have high levels of molecule a called p-S6K, which facilitates cancer growth and may help cancer resist the effects of chemotherapy.

Vistusertib targets mTOR1 and 2 proteins which ‘turn on’ p-S6K. The researchers believe that by combining vistusertib with paclitaxel chemotherapy, the cancer cells can’t use p-S6K to grow and resist chemotherapy.

“Drug combinations hold huge promise for tackling cancer’s adaptation, evolution and drug resistance, just as they have in other areas of medicine such as HIV. But it is essential that we choose which drug combinations to test out in trials rationally based on our scientific understanding of what will work,” said ICR chief executive Professor Paul Workman.

“This study is a perfect example of a rational drug combination, selected because of scientific observations made here at the ICR that resistant ovarian cancer cells seemed to rely on a particular protein for their survival after chemotherapy.”

The study was published in Annals of Oncology and funded by AstraZeneca.