Vaccine Stimulates Immune System to Fight Cancer

London, UK, 15 November 2006: Onyvax Ltd, the biotechnology company developing novel cancer therapies, today announces that the results of a clinical trial of Onyvax-105 in colorectal cancer patients have been published in the November 15 issue of Clinical Cancer Research. The American Association for Cancer Research, publisher of Clinical Cancer Research, has issued a press release which can be accessed at:

http://www.newswise.com/articles/view/525268/

105AD7, the antibody that was the subject of this clinical trial, was invented by Professor Lindy Durrant at Nottingham University. In 1999 Onyvax took an exclusive license to the technology.

The target, CD55, is strongly over-expressed in most cancer types and is prevalent in prostate cancer, Onyvax's principal area of interest. It is thought to be a key molecule in the development of cancer with many mechanisms of action that support tumour growth. Studies to date suggest the most important benefit conferred on the tumour by CD55 is as a defensive shield, protecting the tumour from immune attack.

Onyvax believes that by vaccinating the patient with 105AD7 this defensive shield is removed, allowing the immune system to be more effective in controlling cancer growth. The company is planning clinical trials in prostate cancer in combination with Cell Vaccines to investigate synergy between the technologies.

 

For further information, please contact:

Onyvax
Dr Anthony Walker / Robert Johnson
+44 (0)208 682 9494

Financial Dynamics
Julia Philips
+44 (0)20 7831 3113

 

Notes to editors

Key results of the trial:
In a clinical trial of 67 patients, researchers at the University of Nottingham observed that when Onyvax-105 was administered before and after surgery to remove cancerous tumors, it helped stimulated immune cell production in up to 70 percent of patients.

“This is the first vaccine shown to stimulate TNF-alpha – an immune-system protein that is very effective at killing cancer cells,” said Lindy Durrant, senior author of the study and professor of cancer immunotherapy at the university.

The vaccine works by stimulating the patients' immune response to generate infection-fighting white blood cells called T cells, which in turn produce immune system proteins called cytokines that destroy cancer cells. The antibody contained in the vaccine, called 105AD7, was cloned from a patient who survived seven years with liver metastases from colorectal cancer, Durrant explained.

“This is very unusual as most patients die within one year of getting liver metastases,” she said. “I thought if this antibody had helped this patient, if we could clone it, it might help others.”

105AD7 is structurally similar to CD55, a protein that attaches to sugar molecules and is overexpressed in colorectal cancer cells, protecting them from attack by the body’s immune system. While low levels of CD55 occur in all cells exposed to the immune system, increased expression of the protein has been observed in multiple types of tumors, including up to 80 percent of colorectal cancers.

During the trial -- the largest to date looking at 105AD7 plus surgery -- 67 patients with colorectal cancer who were scheduled for surgery to remove their primary tumor were randomly assigned to receive either 100 micrograms of 105AD7 with a powder to help absorb the vaccine, 105AD7 along with BCG (a bacteria used to stimulate the immune system in cancer patients) during the first immunization and the powder in subsequent vaccinations, or no treatment.

The patients, who had varying degrees of disease, averaged age 66. Twenty-eight patients had colon cancer while in 39 patients the primary tumor was located in the rectum.

Patients were immunized before surgery on the day they were recruited for the study, and again two weeks later if surgery had not yet been performed. The vaccines were continued three, six and 12 weeks after surgery, and then at three monthly intervals up to a maximum of 24 months after surgery. Blood samples were collected from the patients during recruitment, at surgery, and at the time of the three-, six- and 12-week post-operative immunizations. Additional blood samples were acquired one month after each subsequent immunization.

Laboratory tests of the blood samples indicated that a T-cell response against the vaccine was recorded in the majority of patients. The responses tended to have two peaks: one following the start of the immunization schedule and another several months later, after additional immunizations. About 70 percent of patients produced both TNF-alpha and GM-CSF – a protein that stimulates white blood cell production – in response to both the vaccine and to CD55.

“The immune responses to both the vaccine and CD55 were measurable, adding support to the use of CD55 as a target in cancer treatment,” Durrant said.

Nineteen of the patients died during the follow-up period. Durrant and colleagues noted that the trial was not designed to study the effect of the vaccines on survival.

The research was supported by The Research Foundation Stiftelsen Onkologiska Klinikens i Uppsala Forskningsfond.

 

 

Onyvax is committed to the commercialization of new therapies that significantly prolong survival while maintaining a high quality of life for cancer patients. The Company is based in London and has collaborations with leading institutions in Europe and the US. Further information on Onyvax can be found at www.onyvax.com