The future of cancer treatment may come with personalized vaccines designed to control or even prevent relapses – at least if new research published Thursday continues to develop. In a small clinical trial, high-risk melanoma patients receiving such a vaccine were able to have a long-term, sustainable immune response to their cancer, scientists said. They also survived four years after the first treatment, and most were actively disease-free.
Cancer vaccines have been a highly sought after target of scientists for decades. There are two vaccines that can protect against viral diseases that are known to increase the risk of certain cancers, HPV and hepatitis B. But developing a widely effective vaccine that can directly prevent cancer from occurring has been a more difficult task. , thanks to the nature of cancer. First, cancer cells are mutated versions of the cells found in our body, so our immune system cannot recognize them as an enemy as easily as a virus. And because each cancer is specific to each person, making a vaccine that works for everyone is not that easy.
However, in recent years, progress has been made in developing cancer vaccines on a more personal level. Researchers have found that tumors carry proteins on the surface of their cells that don’t appear on normal cells, making them look different from our immune system. These are called proteins neoantigens. By making vaccines that train the immune system to better recognize these neo-antigens, scientists theorize, we can give our bodies a better chance of fighting a known cancer.
Scientists at the Dana Farber Cancer Institute in Massachusetts and elsewhere have been working on one of these vaccines (called NeoVax) for skin cancer melanoma and glioblastoma, the most common brain cancer and one that is very difficult to treat. While their work has shown that the vaccine is well tolerated and appears to trigger an immune response in patients, so far only short-term results are available. Their new paper, published in Nature Medicine, suggests their vaccine also works in the long term.
“These neoantigens are the result of mutations found in a specific tumor – it’s something that originated on an individual level. So our vaccines need to be tailored for a patient’s cancer, ”study author Patrick Ott said over the phone. “But what’s new is that by using genomics and sequencing, we’ve been able to identify these mutations much faster and in a more cost-effective way than before.”
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They gave NeoVax to eight patients at high risk of future, potentially fatal, recurrences of advanced melanoma. They then monitored their health for the next four years, periodically taking blood samples to study the body’s immune response to the cancer, specifically tumor-specific T cells.
The vaccine was given to the patients about 18 weeks after surgery to remove the tumor. Ott and his team found that volunteers continued to carry T cells specific to the neoantigens their vaccine had trained the immune system to memorize. In some people, they also saw T cells that recognized other neoantigens that were specific to their tumor. That’s an indication that their immune system is adapting to any lingering tumor cells in the body by creating even more weapons against them. All eight patients were still alive after nearly four years, and six appeared to be disease-free at last check-in.
At the moment, it takes at most three months from a person’s diagnosis for scientists like Ott to develop a personalized vaccine. But it’s possible that one day these vaccines could be made in a much shorter time, after a simple doctor’s visit. And while they may not be the “universal” cancer vaccine we all hope for, Ott sees no reason why these vaccines could not ultimately be made to help prevent cancer recurrence.
The vaccines can likely be combined with other treatments. Two patients in the study with cancer that spread elsewhere were given immune checkpoint inhibitors, drugs that allow the immune system to better target tumor cells. In these patients, the group found indications that tumor-specific T cells had found their way to the metastatic tumors.
In the future, Ott and his team hope to fine-tune their vaccine technology to create even more powerful immune responses that, when combined with drugs such as immune checkpoint inhibitors, can treat advanced cancer cases. They are now also testing their vaccine with other cancers, while continuing to monitor their existing patients.