2023-06-11 17:05:27
Imagine a future where far fewer women are diagnosed with breast cancer, and women with a family history of the disease do not have to face the difficult and devastating decision that they may have to undergo a preventive mastectomy. Instead, women will receive a series of shots that teach their immune system how to defeat breast cancer before it becomes a problem.
A decade or two ago, this scenario would have sounded fanciful. However, in the last six months, many clinical trials have brought it closer to reality. These studies are very early, and so far only a handful of women have received such injections. However, the publication of several different studies on breast cancer vaccines is an encouraging sign of the amazing progress researchers are making in harnessing the immune system not only to fight cancer – but to prevent it in the first place.
The potential for treating breast cancer – the most common type of cancer among women in the West – is huge. “We are already vaccinating healthy women,” says Susan Domchek, an oncologist from the University of Pennsylvania, who is leading an experiment with such a vaccine, “this is not a fantasy, it is already happening in the field.”
Domchek is one of several researchers making significant progress toward this ambitious goal. Decades of research have been devoted to understanding how to train the immune system to recognize tumors that have reached their peak. From this, a cluster of clinical studies of breast cancer vaccines was created, the aim of which is to prevent the appearance of the disease.
“Eventually there will be vaccines for every type of breast cancer,” says Nora Disis, director of the Cancer Vaccine Institute at the University of Washington. Disis, an expert in breast cancer immunology, believes that there is a high chance that vaccines to treat the disease or prevent its recurrence will reach the public in the next five years. In the future, there will also be vaccines that will prevent women with a genetic risk from developing cancer at all.
One preliminary sign of the promise behind these vaccines was seen in a publication from last November, when the Disis team presented results from a study that lasted several years and dealt with a vaccine that teaches the immune system to recognize a mutation of the HER2 protein – a common cause of breast cancer. Researchers vaccinated 66 women whose cancer was in remission or slowly progressing. The study was designed to prove that the shots were safe, but it also gave hope that this approach did work: The women in the study had a 50 percent chance of dying from the disease within five years of starting treatment, but a decade later 80 percent of them were still alive. The researchers are now conducting a more extensive study.
This injection is just one of several breast cancer vaccines that Disis is developing, with the idea being that preventing the cancer from returning is only the first step towards earlier stages of treating the disease, until it is completely prevented.
Other researchers are also working on vaccines that could prevent disease in women at high risk of developing breast cancer. In general, as part of such experiments, women who are about to undergo preventive mastectomy are vaccinated, so that they can look for an immune response in the tissue removed during the operation. So, of course, these women will need to be followed for years to figure out if the response is enough to prevent the cancer.
Last March, Domchak vaccinated the first three healthy women who carry the BRCA mutation, which puts them at high risk of developing cancer. Before their mastectomies, the volunteers received an injection that teaches the immune system to ‘see’ an enzyme called telomerase, which appears in high amounts in cancer cells. Similarly, last February researchers at the Cleveland Clinic began vaccinating women who do not have breast cancer but carry mutations such as BRCA or PALB2. The injection they receive before surgery teaches their immune system to recognize a protein that is normally only made when women breastfeed, but it seems to reappear in triple negative breast cancer – one of the most aggressive forms of the disease. If it works, the vaccine could be safe for women past their childbearing years.
Proving that such vaccines could prevent cancer would require large, late-stage studies – the kind that academic centers generally cannot afford. “It will take lawyers, patients and funding to do this kind of work,” says Domchak. But when these studies develop in clinics, any positive data will ensure investment in the field, which may bring us closer to the vision of a world with much less cancer.
The patients do their part. Lee Wilke, an oncologist at the University of Wisconsin who is leading a Phase 2 study of one of Disis’ vaccines, says there are many women who would want to roll up their sleeves and participate in the trial.
Wilka routinely performs mastectomies, and is ready for the day when vaccines will allow women to make different choices about their health. Perhaps a vaccine could allow women at high risk of developing breast cancer to delay surgery until after they have had children, perhaps eventually allowing them to forgo surgery altogether and live cancer-free.
“I keep telling my colleagues in research and pharmacology: I want to go bankrupt,” she says. Although normally I wouldn’t wish unemployment on anyone, in this case I think it’s a pretty good goal.
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