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By Ben Hirschler
MADRID, Sept 28 (Reuters) - Using vaccines to fight canceris a field littered with failures but experts believe it ispossible the approach could get a new lease of life if suchshots are combined with a new class of drugs called checkpointinhibitors.
Unlike traditional preventative vaccines, therapeutic cancervaccines are designed for people with established disease andare supposed to boost the patient's immune system to keeptumours at bay.
Unfortunately, the theory has not worked out in practicebecause, while the vaccines are successful at triggering aresponse from the "foot soldiers" of the immune system, cancercells still manage to escape detection.
The result has been a series of failures with high-profileexperimental cancer vaccines such as Merck KGaA's Stimuvax and GlaxoSmithKline's MAGE-A3.
GSK threw in the towel on its vaccine in April, dashinghopes for a project that was once seen as a potentialmultibillion-dollar sales opportunity in lung cancer andmelanoma.
Johan Vansteenkiste of Belgium's University HospitalsLeuven, who led research into use of MAGE-A3 in lung cancer,reported full results of the failure at a medical meeting onSunday and said the setback was a clear disappointment.
But he thinks the new checkpoint inhibitors, which aredesigned to stop the molecular trickery that is used by tumourcells to escape detection by the immune system, could finallyunlock the value of such vaccines.
"For future progress, I think a combination of vaccinationand checkpoint inhibition may be of major interest," he told theEuropean Society of Medical Oncology annual congress in Madrid.
Advances with checkpoint inhibitors - particularly so-calledPD-1 and PD-L1 drugs being developed by Bristol-Myers Squibb, Merck & Co, Roche and AstraZeneca - is dominating discussion at this year's ESMO meeting.
The new drugs are generating promising results in a growingrange of tumour types and scientists are now casting around fornovel ways to combine them with other therapies to get evenbetter outcomes.
Therapeutic vaccines could be one such promising avenue,since they have very few side effects compared to many harshcancer treatments.
Roche Chief Executive Severin Schwan said earlier this monththat the Swiss drugmaker - the world's largest maker of cancerdrugs - was already exploring ways of combining its checkpointinhibitors with vaccines that had failed in tests when given ontheir own. (Editing by William Hardy)
