Vaccine doubles survival in case of brain tumours

June 3rd, 2008 - 3:46 pm ICT by IANS  

Washington, June 3 (IANS) A promising new vaccine boosts immunity in a common and deadly brain tumour and may fend off its recurrence while doubling the survival rate, a new study has found. “This vaccine represents a very promising therapy for a cancer that comes out of the blue and robs people of something most of us take for granted — time,” said John Sampson of Duke University and lead investigator of the study.

“The possibility of doubling expected survival — with few if any side effects — would represent a big step and a lot of hope for this group of patients.”

The vaccine targets a protein expressed on about half of all glioblastoma multiforme (GBM) tumours. The protein, known as EGFRvIII is not expressed in normal tissues but is prevalent in GBMs, which makes it an attractive target for a vaccine, Sampson said.

The vaccine targets the protein and enhances immune response to it, killing tumour cells that express the protein and preventing the re-growth of brain tumours in patients who have already been diagnosed and treated with surgery, chemotherapy and radiation.

This study included 23 patients, treated at Duke and at M.D. Anderson Cancer Centre. Patients had all been diagnosed with GBMs, and had been treated with standard therapy.

They received vaccine injections monthly and were given a chemotherapeutic agent called temozolomide in conjunction with the vaccine treatments.

The temozolomide is thought to enhance the immune response to the EGFRvIII, Sampson said.

“This reflected something of a surprising conclusion, because it stands to reason that chemotherapy, which suppresses the body’s immune system, would make the vaccine less effective,” Sampson said.

“What we found was that the opposite is true. While the body is recovering from chemotherapy, immune response is actually stronger as the immune system overcompensates in order to right itself. It’s the perfect time to introduce a vaccine.”

Patients in the study survived without re-growth of their tumours for a median of 16.6 months, which more than doubles the usual 6.4-month expected progression-free survival in these patients.

Study patients lived for an average of 33.1 months; patients who are diagnosed with GBMs and treated with standard therapy typically live an average of 14.3 months.

The vaccine has caused virtually no side effects; swelling at the injection site is often a patient’s only complaint. A Phase III trial is now open at more than 20 sites nationwide.

Sampson presented these during an oral presentation at the annual American Society of Clinical Oncology meeting in Chicago Monday.

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