Merck KGaA’s colorectal cancer drug is set to propel Australian health authorities headlong into a new era of personalized medicine, in which the results of genetic testing determine which patients have access to the therapy, reports the Sydney Herald Tribune.

The drug, Erbitux (cetuximab), has no chance of working in 40% of bowel cancer patients. Their tumors feature a gene mutation that prevents the molecule from blocking its target cancer growth pathway, the newspaper explains.

Merck KGaA’s colorectal cancer drug is set to propel Australian health authorities headlong into a new era of personalized medicine, in which the results of genetic testing determine which patients have access to the therapy, reports the Sydney Herald Tribune.

The drug, Erbitux (cetuximab), has no chance of working in 40% of bowel cancer patients. Their tumors feature a gene mutation that prevents the molecule from blocking its target cancer growth pathway, the newspaper explains.

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However, for the other 60% whose cancer has the ''wild type'' version of the KRAS gene it offers a decent if usually temporary chance of slowing the cancer. For some it can even shrink tumors enough to make them amenable to surgery - holding out a modest prospect of a cure.

The German drug major’s Merck Serono unit recently reported that the number of patients being KRAS tested to determine if they could benefit from a personalized therapy, such as Erbitux, has leapt from 2.5% in 2008 to 42% in early 2009, noting that nearly a quarter of physicians now carry out KRAS testing (The Pharma Letter June 2).

If Australia’s Pharmaceutical Benefits Advisory Committee this week recommends a subsidy for Erbitux, it will for the first time bring cancer gene testing into the mainstream for a common cancer that affects both men and women, specialists say.

Nick Pavlakis, head of medical oncology at Royal North Shore Hospital - who has worked as a paid adviser to Merck - quoted by the newspaper, said: ''This is the start of the queue of a number of drugs in Australia that are married to having a test...What transpires with this may well apply to other targeted therapies.”

Nicholas Wilcken, director of medical oncology at Westmead Hospital, said it was important to know a patient's KRAS status - even if they could not afford Erbitux, which is only available privately at present - because this might influence how other therapies were offered. However, the Sydney Morning Herald reports, Prof Wilcken said the cost of a genetic test, about A$200 ($169), was prohibitive for some. For people who respond well, the total treatment cost typically exceeds A$20,000.

The federal health department is understood to be discussing how to bring gene tests within its fold. The talks, centred on how tests might be approved and reimbursed under Medicare, are understood to have intensified in recent weeks, the newspaper noted.

© 2010 The Pharma Letter