A novel type of vaccine has shown to nearly double the cancer-free survival time of patients with pancreatic cancer, according to a recent article published in the Journal of Clinical Oncology.
The pancreas is an organ that is surrounded by the stomach, small intestine, bile ducts (tubes that connect the liver to the small intestine), gallbladder, liver, and spleen. The pancreas helps the body to break down food and produces hormones, such as insulin, to regulate the body’s storage and use of food. Pancreatic cancer is often treated with surgery to remove the cancer, chemotherapy, radiation and/or biologic (utilizing the body’s immune system to attack the cancer) therapy. Patients who have cancer that has spread outside the pancreas generally have a poor prognosis with standard treatment methods. Therefore, researchers are exploring novel therapies in an attempt to improve upon present treatment outcomes for patients with this disease.
Vaccines are one type of biologic therapy that directly utilize the body’s immune system to recognize and kill cancer cells while sparing healthy cells from destruction. Different types of vaccines are emerging that prompt the immune system through various selected methods. A novel type of vaccine, called an allogeneic granulocyte-macrophage-colony-stimulating-factor-secreting vaccine, has recently been tested in a preliminary clinical trial for the treatment of pancreatic cancer. The vaccine works as follows: cancer cells are isolated in a laboratory from tissue samples taken from patients with pancreatic cancer. All pancreatic cancer cells, even those from separate individuals, have been shown to display distinct small proteins, called antigens, on their surface. Antigens, such as those found on bacteria or cancer cells, are responsible for eliciting an immune attack. The cancer cells that were isolated are killed with radiation. They are then genetically altered to release a substance, called granulocyte-macrophage-colony-stimulating-factor (GM-CSF), that enhances the production of immune cells in the body. These modified cells are then injected into the patient.
This type of vaccine works through two separate mechanisms. The antigens initiate an immune attack on any cells in the body displaying these antigens – including the existing pancreatic cancer cells. Through mechanisms not yet fully understood, the re-introduction of pancreatic cancer cell antigens through injection stimulates the immune system to attack the existing cancer cells in the body. Augmenting this immune response, the release of GM-CSF further stimulates the immune system to attack any cells displaying these distinct antigens.
Thirteen patients with pancreatic cancer were recently treated with the allogeneic GM-CSF vaccine following surgery. The average disease-free survival time following treatment for these patients was 13 months. Three patients remained cancer-free for approximately 2.5 years. This appears to be a significant improvement, as the average survival time for pancreatic cancer patients receiving standard treatment following surgery is approximately 7.5 months. Additionally, this treatment was well-tolerated in patients, producing minimal side effects.
These encouraging results have lead to the initiation of the next phase of clinical trials evaluating this treatment in order to further define treatment outcomes for pancreatic cancer patients. These results are extremely important as they implicate extended treatment options that may significantly improve disease-free survival for patients with this disease. Patients with pancreatic cancer may wish to speak with their physician about the risks and benefits of participating in a clinical trial utilizing this vaccine.
(Journal of Clinical Oncology, Vol 19, No 1, pp 145-156, 2001)