Can Personalized Cancer Vaccines be used for Mesothelioma?
Research into mesothelioma and other cancers is always evolving, and new options are becoming available on a regular basis. In recent years, clinical trials have taken a look at the efficacy of immunotherapy for mesothelioma patients. More specifically, researchers are interested in personalized cancer vaccines that take into account each patient’s individual requirements.
Understanding Personalized Cancer Vaccines
Every body is different which means that the cancer developing in those bodies is also different among patients. Personalized cancer vaccines essentially cater to a patient’s unique needs by identifying the antigens and molecular makeup of the mesothelioma cells.
Past clinical trials have had difficulty with more generalized vaccines. Antigens that are present in cancerous cells may also show up in healthy cells. Vaccines that aren’t personalized may make no attempt to attack these tumor cells because they are designed to leave them alone.
To make personalized cancer vaccines, scientists have had to look at each individual patient and how the disease presents in their body alone. To do this, they take a biopsy of the affected tissue or tumor and cross-reference those cancerous cells with the DNA sequence of the person’s healthy cells. The DNA sequence of a healthy cell could be drastically different than that of a cancerous cell. On top of that, it’s virtually impossible for the antigens found in one person to be identical to the antigens of another.
For every 100 cancerous mutations, about 3 to 5 actually produce antigens. These are often referred to as “neoantigens” because they don’t come from normal, healthy cells. Doctors can look at these neoantigens and begin developing a vaccine that will target only those antigens. The vaccine is often combined with adjuvants, or modifying agents that help enhance immune response and improve vaccine activity. Only a single neoantigen is required to make a vaccine, but more neoantigens often produce better results.
What Has the Research Shown?
There have been two very promising clinical trials that look at personalized cancer vaccines for mesothelioma (or a similar disease) in the last few years. One 2016 study published in the American Journal of Respiratory and Critical Care Medicine, looked at a dendritic cell-based cancer vaccine in combination with chemotherapy as a treatment for mesothelioma. Dendritic cells have long been known to provoke an immune response by processing antigens and activating T cells in the lymph nodes. The response attacks cancerous cells at the source.
The study observed 10 patients who had malignant pleural mesothelioma. The group was administered dendritic cell vaccination while also taking low doses of the chemotherapy medication, cyclophosphamide. The worst side effect reported by the researchers was a mild fever. Otherwise, the combination therapy showed encouraging results with seven patients earning a survival rate of two years or more, which is already a higher rate than most mesothelioma patients are afforded. Two patients achieved survival rates of 50 and 66 months.
A 2017 study published in the journal, Nature, took a look at patients suffering from melanoma. This is important for mesothelioma patients because the two diseases are actually very genetically similar. There were six patients in this study, all of whom were given neoantigen vaccines about 18 weeks after cytoreductive surgery. Over the course of 25 months, 4 patients were completely free of the melanoma even though the disease had been in a later stage. The remaining two patients experienced a recurrence of the disease, but after further immunotherapeutic treatments, the disease went into remission.
Both of these studies provide a gleam of hope for mesothelioma sufferers, even if more research is required on personalized vaccines.
The Future of Cancer Vaccines
The prospect of personalized cancer vaccines is exciting. If doctors can adapt treatments for specific patients, it will make it easier in the long-run to treat anyone with any kind of cancer. The Partnership for Accelerating Cancer Therapies (PACT) is also looking to bring immunotherapy into the forefront. The topic, so far, hasn’t been researched fully, but more clinical trials are on their way. In the future, patients could be getting extremely individualized care from their doctors.
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