British journal details latest in immunotherapy for mesothelioma
Researchers with the National Cancer Institute report that three therapeutic vaccines being tested against mesothelioma show promise against the deadly disease.
In the July issue of The Lancet, a British medical journal, two scientists summarized clinical trials involving the vaccines' effect on mesothelioma. Therapeutic vaccines don't prevent disease, but rather “treat” the cancer using the body's own immune system.
The vaccines, or immunotherapies, are an important advance in the search for cancer treatments. That's because conventional cancer treatments such as chemotherapy compromise the body’s primary biological tool for combating disease, its immune system. Immunotherapy essentially tricks the immune system into recognizing cancer cells as foreign substances, triggering an attack on those cells.
Dendritic cell-based immunotherapy uses the patient's own unique cells to provoke an immune response against cancers that produce a specific antigen. The Dendritic cells, called DC cells, are harvested from the patient, then stimulated, or primed, with an antigen that triggers a tumor-inhibiting response. Once returned to the body, the DC cells generate effectors that attack and kill the tumor cells expressing the antigen that has been primed.
Listeria-based immunotherapy uses a live virus, Listeria, to infect tumor cells that produce an antigen. Listeria is a potent bacterium, but it produces chemicals that allows it to sneak into cells via a process called active phagocytosis. Once inside the tumor cell, it elicits an innate or acquired response from the body's immune system.
WT1 analogue peptide vaccines seek out certain chemicals in mesothelioma and non-small-cell lung cancer to induce immune responses in the body's T-cells.
In addition to strengthening the immune system, immunotherapy can also alter biological processes that can prevent the spread of tumors.
Mesothelioma, which is caused by asbestos, has proven resistant to even the most up-to-date chemotherapy regimens, which have lengthened survival times by only a few months on average. Mesothelioma is a difficult disease to treat because it has a long latency period, meaning it's typically diagnosed in later stages, when patients tend to be in their 60s or older.