Breast cancer vaccine delays progression in trial

A vaccine that could be used in up to 80 per cent of all cases of breast cancer seems to have slowed progression of the disease in an early-stage clinical trial.

Around half of the 14 patients treated with the vaccine in the Phase I showed no evidence of disease progression after one year, compared to approximately 20 per cent of a matched placebo group, which was a statistically significant different.

The researchers behind the vaccine – from Washington University School of Medicine in St. Louis, US – caution that the trial was only designed to test the drug’s safety so it would be premature to make any judgment on efficacy.

Nevertheless, the finding suggests that the vaccine was priming the patients’ immune systems to attack tumour cells, which they intend to examine further in a larger, follow-up clinical trial.

The DNA-based vaccine targets mammaglobin-A (MAM-A), a protein overexpressed in 40 to 80 per cent of primary breast cancers but which does not seem to be present in large amounts in other tissues of the body, according to the scientist, who have published their work in Clinical Cancer Research.

“In theory, this means we could treat a large number of breast cancer patients with potentially fewer side effects,” said lead investigator William Gillanders, a breast cancer surgeon at Washington University.

The team are particularly excited by the finding that the vaccine seems to work even in patients with more advanced disease, which typically means their immune systems are compromised.

“Despite the weakened immune systems in these patients, we did observe a biologic response to the vaccine while analysing immune cells in their blood samples,” said Gillanders. “That’s very encouraging.”

The researchers now want to carry out a larger clinical trial to test the vaccine in newly-diagnosed breast cancer patients, who should have more robust immune systems and – in theory at least – should derive the most benefit from the therapy.

Vaccines against cancer have remained something of an elusive target for the pharma industry to date, despite decades of research.

One of the first companies to bring a cancer vaccine to market – Dendreon with its prostate cancer therapy Provenge – was recently forced to file for bankruptcy after lacklustre sales of the drug.

Meanwhile, both GlaxoSmithKline (GSK) and Merck Serono have both reported disappointing results in late-stage lung cancer vaccine trials in recent months, with the latter dropping its tecemotide candidate in September and GSK pulling the plug on MAGE-A3 in April.


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