This transnational clinical study is aimed at finding how to develop and produce a vaccine for colon cancer, Associate Professor Dr Narin Voravud of Chulalongkorn University Hospital’s Medical Oncology Unit said.
“The project is being submitted to Chulalongkorn University’s ethics committee for approval,” he said.
Narin met with Dr Toh Han Chong, who leads the NCCS, on Wednesday to discuss their plan to conduct a clinical trial on the use of the dendritic cell vaccine for the treatment of advanced colon cancer in Thailand.
The vaccine has been developed by the NCCS, a team of Danish doctors, and Biotech since 2006.
In a study conducted by NCCS researchers and the Danish team, about 20 patients were given 10 injections over five months, or once every two weeks. The vaccine was injected under the skin. No significant side effects were found. However, many of the patients had received conventional treatments before they entered the clinical trial.
The researchers selected colorectalcancer patients with specific proteins on the cell surfaces, which the vaccine is meant to target, Toh said.
Dendritic cells are very specialised white blood cells that help the immune system recognise and destroy antigens. They are considered the most powerful vehicle for cancervaccine production. DCs are cultivated from the patient’s blood; when they are reinjected, they recognise the antigens on the patient’s cancer cells through the T cells.
Sometimes specific genes are added to DCs to stimulate the patient’s immune system. Once in the body, the manipulated DC vaccine cells target the cancer cells, as well as recruit other cells such as T cells in the immune system to join the fight.
Most people suffering from colorectal cancer develop an advanced form of the disease and median survival time is between six and nine months without treatment.
Toh explained that treating cancer patients with a cellbased vaccine was different from chemotherapy, as the vaccine will specifically trigger white blood cells to destroy the tumour cells, while chemotherapy will kill all cancerous cells as well as destroying healthy cells. Chemotherapy targets fastgrowing cells in the patient’s body, not all of which are necessarily cancerous.
Toh said published test results had shown that two of 20 patients in the initial study had responded to the vaccine at a satisfactory level, as their condition had slightly improved four years after receiving the vaccine.
“We found that the vaccine could not cure every patient. It could only prolong the patient’s life,” Toh said.
“So far, we still cannot answer why the cancerous cells in the patients stop growing after they received the vaccine injection. We just know that the vaccine improved the patients’ condition.”
To date, only prostate therapeutic vaccine had been approved by the US Food and Drug Administration. The cost of treatment was estimated about Bt3 million per three injections.