Quick Dips

On the Way to a Cancer Vaccine

Fifteen years of research in Christchurch on a cell which some scientists didn't believe existed has resulted in clinical trials for a new immunotherapy treatment for cancer.

Professor Derek Hart and Dr Judith McKenzie of the Haematology/Immunology Research Group at the Christchurch School of Medicine have studied the dendritic cell since 1981, largely funded by Health Research Council grants. This cell makes up only 0.1% of white blood cells, but is a major immune response initiator. The group is analysing the wide variety of molecules which dendritic cells use to communicate with T lymphocytes, another type of white blood cell active in the immune response.

The part of their work which has generated intense international interest is their investigation of how dendritic cells respond to cancer cells, including breast, lymphoma and prostrate cancer.

"We've proven that we can get an immune response from dendritic cells in vitro to the target molecule from chronic myeloid leukemia," says Hart. "We're improving the loading of target cancer molecules into dendritic cells in the laboratory, so that when dendritic cells present cancer cells to the immune system, we can create a more effective immune response."

Two years ago, the group produced a monoclonal antibody, CMRF-44, which identifies and binds with dendritic cells.

"This was a big step forward in identifying dendritic cells for scientific studies and clinical use," says Hart.

Only one other such antibody has been created. The laboratory has just isolated another antibody, CMRF-56, which is being characterised further. These antibodies have significantly improved DC purification and administration to women with low levels of breast cancer. This is the first step to testing its effectiveness as a cancer vaccine.

"We're talking about an entirely new mode of treatment, a biological therapy using human cells," says Hart.

Having developed techniques which separate dendritic cells from other white blood cells, the group is now trying to grow large numbers of dendritic cells. Hart believes that eventually health workers will be able to take a blood sample from a patient, grow their own dendritic cells, store them and vaccinate the person every few months.

"I'm pretty sure that we will be able to get rid of low levels of cancer cells, at least in some cancers," says Hart. "We'll probably need several vaccinations to get a strong enough immune response."

Having gone in a few years from a group investigating a cell which some said didn't exist to a group with a sought-after immunotherapy tool has given the team the speed wobbles. Joanne Crighton has been employed as business co-ordinator, to help establish clinical trials and manage other spin offs from their research.

"We've been doing the basic science, working out what molecules dendritic cells use," says Hart, "but when people see a clinical application the basic science gets leapfrogged. We need to continue the basic science as well as the clinical testing."

The Christchurch research has helped establish dendritic cells as an important new research field, and many other researchers are trying to grow the cells and start clinical trials.

Jenny Rankine, HRC