An experimental cancer vaccine turned tumor cells into traitors

MRI brain images.

MRI brain images.

A team of scientists seeks to make cancer its worst enemy. Their experimental vaccine candidate uses modified tumor cells to deliver a toxic payload to the rest of the cancer, while allowing the immune system to more easily target and remember the cancer in the future. In new research, the vaccine has shown promising results against the most common form of brain cancer, at least in mice.

Cancer vaccines are generally therapeutic, which means that they are intended to treat existing cancers or prevent them from coming back. They’re trying to exploit a flaw in Cancer’s armor that normally allows it to evade the immune system. Often this has been done by training immune cells to recognize certain key elements of cancer cells, such as cancer-specific proteins, using inactivated cancer cells or another method of delivery (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 engineer them into traitors.

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

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

In a study published in Science Translational Medicine, the team reported their first 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 human-like immune systems, the vaccine appears to be safe and effective in killing tumors, eliciting a long-lasting immune response and prolonging mouse survival.

Animal studies are important, but they are only the beginning of demonstrating that an experimental treatment might work in humans. That said, the success seen in humanized mice bodes well for future studies. And the team argues that their cell-based vaccine could eventually 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 tumor cell-based vaccines and hope 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.

Assuming the team’s research continues to bear fruit, Shah added, clinical trials of their vaccine could 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 in humans as well.

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