23 Feb 2007

New anti-cancer strategy

Researchers from Rockefeller University say that the cancer drug bortezomib (Velcade) has the potential to enhance cancer patients' immunity to tumours.

The new research suggests that when treating cancer, it's not just killing the cancer cells that matters. How they are killed may be just as important in determining the effectiveness of a cancer treatment.

For a study published this week online by the journal Blood, researchers tested the effects of the chemotherapy drug bortezomib in tissue culture containing multiple myeloma cells. Multiple myeloma is a cancer of immune cells in the bone marrow.

Helps spot cancer cells
The researchers found that bortezomib's action on cancer cells may enable the immune system to recognise them, which could potentially help cancer patients' fight the disease more effectively.

After exposure to bortezomib, the multiple myeloma cells died in such a way that a heat shock protein, called hsp90, migrated to their surfaces. A group of immune cells, called dendritic cells, are activated when they encounter hsp90 on the dying tumour cells. This causes the dendritic cells to ingest the dying cancer cells and present them to memory and killer T-cells.

If replicated in humans, this progression could potentially lead to enhanced immunity.

"If you could directly target the drug to these cells, it may be sufficient enough to create a vaccine. The exposure of heat shock proteins on dying cells represents an immunogenic form of cell death," Madhav Dhodapkar, head of the Laboratory of Tumour Immunology and Immunotherapy at Rockefeller University, said in a prepared statement.

May work on various cancers
The immunity-enhancing effects of bortezomib also seem to extend to other types of cancers.

When the researchers treated lymphoma and breast cancer cells with bortezomib, the dying cells experienced the same increase in hsp90.

What is unclear is whether these findings will extend to actual immune responses in humans. If it does, the researchers hope to directly target tumours in cancer patients.

"A simple experiment that hasn't been done yet is simply injecting bortezomib directly into tumours. By directly targeting the tumour, rather than injecting the drug intravenously, we may be able to take better advantage of bortezomib's distinct properties," said Dhodapkar. – (HealthDayNews)