New drug blocks common cancer pathway

Scientists have developed a new drug which can reduce the growth of tumours* in mice by up to 98 per cent, according to a study published in Molecular Cancer Therapeutics ** this week.

The work was carried out by researchers from Cancer Research UK's Centre for Cancer Therapeutics at The Institute of Cancer Research (ICR), with the biotechnology company Piramed - now owned by Roche***.

In this study, the team of scientists found that the drug reduced the growth of glioblastoma - the most common form of brain tumour - in mice by 98 per cent and decreased the growth of ovarian tumours in mice by 80 per cent. In separate investigations, scientists also found the drug worked against a number of cell lines derived from other human cancers.

The team used markers to show how the drug works by targeting the PI3 kinase pathway ****, which is known to be linked to the growth and spread of many cancers.

The drug works by blocking this pathway which is often 'hijacked' in human cancers - enabling them to grow and spread. It corrects faulty genetic signals that cause unrestricted cancer progression, as well as preventing the function of cells in the body that support the tumour by increasing its essential blood supply - a process called angiogenesis.

The researchers who conducted these laboratory studies believe that GDC-0941, licensed to Genentech by Piramed, may have potential in a wide range of human cancers. At Genentech, GDC-0941 has progressed into Phase I clinical trials in the UK and the USA. Scientists and oncologists from Genentech have designed several trials to determine how GDC-0941 works in humans.

Lead author of the article describing the pre-clinical lab studies, Professor Paul Workman, director of the Cancer Research UK Centre for Cancer Therapeutics at the ICR said: "We know the PI3 kinase super-highway is hijacked in many cancers. We show here that GDC-0941 works in the way it was designed to, inhibiting the PI3 kinase pathway and blocking tumour growth."

"Our hope is that that we have created a potent anti-cancer weapon that directly targets the processes which feed the cancer cells while sparing most of the healthy cells. But it's early days and we still have a lot to learn about the potential of this drug. The next step is to see if the drug targets human cancers as effectively."

The Institute of Cancer Research's chief executive Professor Peter Rigby said: "We are very excited about the promise this drug is showing in targeting a range of cancers in the laboratory, and look forward to the results of the ongoing clinical trials."

Cancer Research UK's chief executive, Harpal Kumar, said: "We're delighted to see our investment over many years in understanding this aspect of cancer bear fruit in the form of a drug that is showing promise in early studies. We hope further investigation into this drug will continue to yield positive results which could lead to a powerful new weapon to treat a wide range of cancers."

*This percentage growth was measured by comparing the size of the tumours growing in the mice that were given the drug in comparison to the mice that were not given it.

**Biological properties of potent inhibitors of class I phosphatidylinositide 3-kinases: from P1-103 through P1-540, P1-620 to the oral agent GCD-0941. Molecular Cancer Therapeutics. F. Raynard. July 2009.

***This work was carried out by the Cancer Research UK Centre for Cancer Therapeutics and the start-up company Piramed, which was established by Cancer Research Technology (CRT), The Institute of Cancer Research (ICR) and the Ludwig Institute of Cancer Research. Cancer Research UK has supported much of this work. The development of this drug is being carried out by Genentech, which licensed the drug from Piramed, and is now owned by Roche.

****PI3 kinase is the short name for the phosphatidylinositide 3-kinase.