An Experimental Cancer Vaccine Turned Tumor Cells Into Traitors

In experiments with mice, the vaccine appeared safe and effective at killing brain cancers and preventing their return.

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MRI brain images.
MRI brain images.
Image: Shutterstock (Shutterstock)

A team of scientists are looking to turn cancer into its own worst enemy. Their experimental vaccine candidate uses tumor cells modified to deliver a toxic payload to the rest of the cancer, while also making it easier for the immune system to target and remember the cancer in the future. In new research, the vaccine delivered promising results against the most common form of brain cancer—at least in mice.

Cancer vaccines are generally therapeutic, meaning that they’re meant to treat existing cancers or prevent them from returning. They try to exploit a kink in the cancer’s armor that normally allows it to evade the immune system. Often, this has been done by training immune cells to recognize some key part of a cancer’s cells, such as cancer-specific proteins, using inactivated cancer cells or some other delivery method (including viruses). But researchers at Harvard Medical School and Brigham and Women’s Hospital, led by Khalid Shah, are working on a slightly different approach. Their plan is to take living cancer cells and genetically modify them into traitors.

“Our team has pursued a simple idea: to take cancer cells and transform them into cancer killers and vaccines,” said Shah, director of the Center for Stem Cell and Translational Immunotherapy at Harvard and Brigham, in a statement provided to Gizmodo.

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By keeping the cancer cells alive, the team hopes to exploit their natural tendency to seek out their own kind. But these engineered therapeutic tumor cells—or ThTCs, as the researchers have coined them—are modified using CRISPR-Cas9 in two important ways. First, the cells are meant to produce potent tumor-killing agents. And second, they’re supposed to produce other proteins that will get the immune system’s attention, ideally meaning that the body can naturally form long-term immunity against the cancer. To further ensure the safety of the treatment, the cells are programmed to carry a double kill-switch that should allow them to be easily destroyed if they try to keep spreading.

In a study published in Science Translational Medicine, the team reported their early findings using the vaccine against glioblastoma tumors, the most common and often deadly form of brain cancer. Across different strains of mice, including mice bred to have a human-like immune system, the vaccine appeared to be safe and effective at killing the tumors, provoking a durable immune response and extending the survival of the mice.

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Animal studies are important, but they’re only the beginning of showing that an experimental treatment might work in people. That said, the success seen in humanized mice does bode well for future studies. And the team argues that their cell-based vaccine could possibly be used to treat and prevent a wide variety of solid tumors throughout the body.

“We are developing the next generation of autologous and allogeneic engineered tumor cell based vaccines and are hopeful that our therapeutic strategy will have the potential to impact patients by preventing tumor progression, recurrence, and metastasis,” said Shah in an email to Gizmodo.

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Assuming that the team’s research continues to bear fruit, Shah added, clinical trials of their vaccine might arrive in three to five years. Other cancer vaccines, including those made using the same mRNA-based platform in covid-19 vaccines, are already being tested out in humans as well.