Experimental ovarian cancer drug shrinks tumours in early trial – expert comment

Conducted by the Institute of Cancer Research and the Royal Marsden NHS Foundation Trust London, the safety trial for the drug ONX-0801 was carried out in a small trial of 15 women with an advanced stage of the disease. They found a ‘very promising’ clinical response where the tumours in half of the women shrank.

The drug is the first of a new class developed by the Institute of Cancer Research that mimic folic acid and its ability to selectively target cancer cells and avoid healthy tissues. In doing so, this could reduce the side-effects often associated with chemotherapy, such as infections, nerve damage and hair loss.

The prognosis of ovarian cancer in its advanced stages is very poor and is a challenging disease to treat. In 2014, more than 4,000 women died from the disease in the UK and in 2012, it was estimated that 152,000 died from ovarian cancer worldwide. Unfortunately the symptoms, including abdominal pain, back pain and irregular bleeding, are vague and the disease is not diagnosed until the latter stages in nearly two-thirds of cases in the UK.

How important are these results in tackling late stage ovarian cancer and what are the next steps? Michel Coleman, Professor of Epidemiology and Vital Statistics and Head of the Cancer Survival Group at the London School of Hygiene & Tropical Medicine, said: “Shrinkage of tumours is important, but as the authors point out, that is not the same as producing the hoped-for extension of survival for women with ovarian cancer.  The longer-term effects of the drug have not yet been reported.  Also, this promising result has only been seen so far in a very small subset of 15 women who were taking part in a study to test the safety of the drug (Phase I trial). 

“The excitement of the investigators is completely understandable, but one should be cautious about interpreting this result as a breakthrough for ovarian cancer patients until data on longer-term outcomes are available.”