Immunotherapy has become such an important aspect of cancer research after showing great promise for so many cancers, including mesothelioma. As research continues to show just how unique each case of cancer truly is from patient to patient, the need for personalized medicine continues to be pushed to the forefront. As such, one form of cancer immunotherapy, called personalized cancer vaccines, has become an increasingly important aspect of research.
What Are Personalized Cancer Vaccines?
Personalized cancer vaccines are a type of immunotherapy made to be totally unique for each individual patient. As researchers continued to study different types of immunotherapy, one reason for why this new treatment doesn’t work for everyone became glaringly apparent. Even patients with the same type of cancer have tumors with a unique molecular makeup, specifically the antigens the cancer cells host.
Antigens are molecules that can induce an immune system response, as they stimulate the body to create antibodies to fight this foreign toxin off. The trouble lies in some tumor cells that sport the same antigen as normal cells, which the immune system understands not to attack. This has led to difficulties in some past clinical trials with cancer vaccines, where the treatment wasn’t truly personalized.
Since then, researchers have focused on the new approach of creating personalized cancer vaccines. For this treatment, doctors biopsy an individual patient’s tumor to sequence the DNA and compare these sequences to that of a normal, healthy cell. Studying antigens on an individual level is key, as doctors note it’s highly unlikely that these will be the same among any two cancer patients. The differences between the normal and cancer cells, mutations, can be few or even up to 1,000.
After recognizing these mutations, researchers can then identify which mutated genes make antigens that can then be targeted by a cancer vaccine. It’s estimated that about 3 or 5 out of every 100 mutations makes an antigen. Because these antigens (sometimes labeled neoantigens) aren’t made by healthy cells, the doctors can then synthesize the tumors’ antigens into a vaccine with adjuvants which will enhance the immune response. Researchers have noted that it only takes one of these neoantigens to make the vaccine, but experts note that 20 antigens can maximize the effects and make it more likely the vaccine is successful.
Research in Personalized Cancer Vaccines
Since the initial findings, there have been some successful clinical trials testing these vaccines for some different cancers. One study from the summer released results of the use of personalized vaccines on melanoma patients. This study could be particularly promising even for mesothelioma patients, since melanoma has already been found to be genetically similar to mesothelioma.
The neoantigen vaccines in this study were created for six patients who showed cancer mutations in their melanoma tumors, and thus could possibly see effective results from the treatment. On average, these patients received their vaccines about 18 weeks after having cytoreductive surgery. Researchers noted that the treatment produced some side effects, like the flu. But the end results were worth some of these symptoms.
After 25 months, four patients who had later-stage skin cancer saw no disease recurrence. Two patients saw recurrence at this time, but were then treated with another type of immunotherapy which ultimately led to complete remission. Though the trial was only held among a small group of patients, the researchers believed it was a good step in exploring the safety and efficacy of a personalized cancer vaccine as a treatment alone or with other immunotherapies.
Another study observed a type of personalized vaccine for mesothelioma. Researchers tested a dendritic cell vaccination in combination with chemotherapy to determine if the vaccine could be more effective. Dendritic cells have been studied in immunotherapy for some time because of their natural ability to induce an immune response. These cells can process antigens, then migrating to the lymph nodes and activating the T cells that can cause an immune response against cancerous cells.
In this particular study, cancer immunologists tested the efficacy of dendritic cell vaccination with a low dose of the chemotherapy drug cyclophosphamide on ten patients with malignant pleural mesothelioma. Researchers found the treatment to be safe, with only mild fever reported in some patients, and effective. Seven of the patients achieved survival of 24 months or longer, which is longer than the average mesothelioma survival. Two of the patients were still alive after even 50 and 66 months.
Though this study was also only among a smaller group of patients, the results suggest it could lead to a larger clinical trial in the future. These two studies and several other around the efficacy of personalized cancer treatments have all shown promising results for the future, and will hopefully lead to larger studies with even more impactful results going forward.
What’s Next for Cancer Vaccines?
Immunotherapy is an increasingly important aspect of cancer research. Through efforts like the Cancer Moonshot, which recently revealed the Partnership for Accelerating Cancer Therapies (PACT) focusing specifically on improving immunotherapy for all kinds of cancer, this emerging treatment will hopefully only become more effective with further study.
Molecular testing has become more of a norm for cancer treatment, to see if patients are eligible for treatments like these cancer vaccines. Many believe precision, or personalized, medicine is truly the way to a cure for cancer and other health conditions. With more study, precision medicine could not only help tailor treatments, but also provide preventive measures for each individual patient.
