“[This] is the first human study on DC-based immunotherapy in patients with mesothelioma," wrote Joachim G. Aerts, a pulmonary physician at Erasmus Medical Center in the Netherlands. His paper was published in the American Thoracic Society’s American Journal of Respiratory and Critical Care Medicine.
The incidence of mesothelioma has been increasing in recent years because the disease takes up to 50 years to develop after exposure to asbestos, and use of asbestos has been heavily regulated in the United States only since 1970. The disorder, which is expected to rise in prevalence until about 2020, has an average survival time of about 12 months after diagnosis. Chemotherapy might add just three months to this time.
Because of the gravity of the disease, the rising rate of new cases, and the limited treatment options, researchers have been paying particular attention to mesothelioma, especially in the area of attacking it through the body’s own immune system.
“The possibility to harness the potency and specificity of the immune system underlies the growing interest in cancer immunotherapy,” said Aerts. “One such approach uses the patient’s own DC to present tumor-associated antigens and thereby generate tumor-specific immunity.”
Aerts’ previous research used mice to show that a dendritic-cell vaccine could marshal the immune system against tumors and increase the animals’ survival time. In his current experiment, the scientist chose 10 human patients recently diagnosed with malignant pleural mesothelioma. The research team cultured immature dendritic cells from each patient’s blood and exposed them to the antigen produced by each person’s tumor. The DCs were then matured and injected back into each patient in three doses over the course of two weeks.
Each participant’s blood showed a significant boost in cancer antibodies. Four patients’ tumors had enough material for testing, and these samples showed that anti-tumor cytotoxicity had been induced after vaccination. Three participants exhibited tumor regression, though it could not be determined if this was from the vaccine.
Very important, the patients displayed no sign of autoimmune diseases or other serious side effects. Eight of the participants did develop flu-like symptoms after the shots, but seven of them normalized after a day.
“The major problem in mesothelioma is that the immunosuppressive environment caused by the tumor will negatively influence our therapy,” said Aerts. “So we are now working on a method to lower this immunosuppressive environment. We hope that by further development of our method it will be possible to increase survival in patients with mesothelioma and eventually vaccinate persons who have been in contact with asbestos to prevent them from getting asbestos-related diseases.”