Up until the mid-1970s, people who were diagnosed with malignant mesothelioma were caught completely unaware. But as word spread about the link between asbestos and the rare form of cancer, people with a history of exposure to the carcinogen have lived with the knowledge of their vulnerability. For researchers, the known risk presents an intriguing question: Would it be possible to create a mesothelioma vaccine that could offer protection to those who are at risk?
Current Mesothelioma Treatments
Patients who have been diagnosed with malignant mesothelioma face a grim future. Despite intense work on the part of researchers and physicians, the rare, asbestos-related disease continues to be considered fatal. The gold standard treatments of chemotherapy, surgery, and radiation therapy, as well as innovative treatments using immunotherapy, have fallen short of delivering survival times significantly longer than the existing median of 18 months after diagnosis.[1]
While some scientists work collaboratively with surgeons and medical oncologists to test new combinations of treatments that offer incremental improvements in patient outcomes and quality of life, others are exploring the possibility that mesothelioma vaccines can more effectively stimulate the immune system and generate a more impactful response.
What Are Cancer Vaccines?
We are all familiar with vaccinations against childhood diseases and viruses like influenza, Hepatitis B, and most recently COVID-19. These are made using weakened or harmless versions of the disease that we are trying to protect against that stimulate the immune system into action. When these weakened versions of the disease are introduced into our bodies, they stimulate our immune system to make antibodies that recognize the disease and attack it if a real version were to appear.[2]
Cancer vaccines do not act in the same way as typical preventative vaccines. Rather than being administered before the disease affects the patient, patients are not treated with cancer vaccines until the cancer is already present. Still, just as vaccines against a virus recognize an antigen known to appear on the surface of a specific virus’s cells and trigger the immune system to attack the cells when they appear, cancer vaccines are engineered to teach the immune system to react to the presence of proteins that exist on the specific cancer’s cell surface. The vaccine triggers a response from the immune system that attacks the cancer cells.[2]
Types of Cancer Vaccines
As scientists have learned more about the uses of vaccines against cancer, different types of vaccines have been created. These include:[2]
- Protein or peptide vaccines – These are made from small pieces of protein found in the specific cancer that scientists have created in the lab. They stimulate the immune system to attack when those peptides are present.
- DNA and mRNA vaccines – These are injected into the body to help the immune system respond more effectively to the presence of a specific cancer cell.
- Whole-cell vaccines – Rather than searching for a specific antigen that has been identified for a type of cancer, whole-cell vaccines are generated from the patient’s own cancer cells. They make it easier for the vaccine to find the cancer cells because they are an exact genetic match to the patient’s cancer.
- Dendritic cell vaccines – These vaccines attack abnormal cells. The dendritic cells that they contain are grown alongside cancer cells in the laboratory, and when administered they help the immune system find and attack the cancer.
- Virus vaccines – These vaccines alter viruses in the laboratory and use them as a messenger that finds and enters cancer cells and then delivers cancer-fighting drugs directly into the cancer cells.
Clinical Trials of Mesothelioma-Fighting Vaccines
There are several biopharmaceutical companies and researchers from cancer centers working diligently on the creation of vaccines that specifically energize the immune system against malignant mesothelioma. These varying approaches have been supported by clinical trials showing that the immune system recognizes the rare form of cancer on its own, but has a muted response to the aggressive tumors.
Whether designed to treat or prevent mesothelioma, vaccines are a form of immunotherapy. Vaccines created from components of the patient’s tumor or tissue from other mesothelioma patients’ tumors are used to generate an immune response. This has proven particularly helpful when patients have already undergone surgery or chemotherapy, as the approach seems to optimize the immune system’s response. Interestingly the same approach has shown some preventative success when administered to people at high risk for mesothelioma due to heavy asbestos exposure.[3]
One notable effort conducted by researchers from the Drug Research Program and ImmunoViro Therapy lab at the University of Helsinki identified peptides on the surface of malignant pleural mesothelioma cells, then used T cells from human healthy donors to deliver the most promising peptides to create virus-based precision immunotherapy. In testing its effectiveness on mouse models, the group demonstrated the potential for an effective strategy for treating unresectable tumors.[4]
A test of an mRNA-based cancer vaccine approach to mesothelioma identified specific antigens on the rare cancer’s cell surface that have the potential for vaccine development.[5] It further identified the immune subtypes of patients who are most likely to benefit from the treatment, while a peptide-based approach to mesothelioma vaccines tested its use in conjunction with immunotherapy drugs Opdivo and Yervoy as a second-line cancer treatment after platinum chemotherapy.[6]
