HAMBURG — Beata Halassy’s breast cancer was stubborn. In 2016, doctors discovered the tumor — a rather rare, aggressive form. They operated on Halassy, removing her left breast, and she underwent chemotherapy. But the cancer returned. It was removed again and returned in 2020 once more.
A full recovery seemed unlikely. At best, the doctors said the cancer would become chronic and could be suppressed for many more years. At worst, it would be unstoppable.
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Regardless, Halassy would need another round of chemotherapy. But during her first treatment, her hair fell out, she often vomited and her mucous membranes bled. She didn’t want any more chemotherapy, she told Die Zeit during a telephone interview.
And so she came up with a bold idea. Halassy works as a molecular biologist at the Center for Virus Immunology and Vaccines at the University of Zagreb in Croatia. “I listened to the scientist in me,” she says. ”I was curious to see if I could get completely healthy again.”
So she started a self-experiment, supported by her colleagues and supervised by an oncologist: Halassy underwent a treatment involving modified viruses aimed at attacking the tumor — an approach not previously tested in this form.
Now, four years later, the cancer has not returned — and Halassy has become somewhat of a celebrity. Nature magazine highlighted her case study, which has since gained international attention.
But experts are also debating whether such self-experiments are unethical because they might encourage cancer patients to resort to unproven treatments. Nature concluded that Halassy’s case is ethically sound.
Since the media attention, Halassy says she receives countless emails from women worldwide seeking her guidance for treatment. But Halassy is not a doctor. Even if she were, the therapy she tried would need further development and testing in clinical trials.
Viruses vs. cancer cells
Many viruses preferentially infect cancer cells because these cells lack the natural defense mechanisms present in healthy body cells. This vulnerability has been known since the 1950s, leading to ongoing research into using viruses against cancer.
In 2015, the first such drug was approved — a genetically modified herpes virus for melanoma. But progress has been slow since then; many studies have failed to yield successful cancer treatments using oncolytic viruses.
Halassy points to a systemic problem that experts in Germany also acknowledge. This contributed to her decision to conduct her self-experiment.
Breast cancer is now highly treatable due to significant advancements over recent decades. Most tumors grow due to hormones like estrogen or progesterone and can often be treated hormonally without chemotherapy. Increasingly, masectomy is not always necessary.
Third tumor
A 2023 study from the UK found that in the 1990s, 14% of women diagnosed with early-stage breast cancer died within five years; between 2010 and 2015, this rate dropped to 5%, and it may have fallen to 3% today.
No ethics committee would have approved the study
Initially, however, Halassy suffered from the most severe form of breast cancer — a rare “triple-negative” tumor that lacks specific surface proteins targeted by hormone therapies. This led her to choose viral therapy.
Only after starting her self-experiment did she discover that her third tumor had changed and could have been treated with medication. Thus, Halassy became a fortunate case for science: likely no ethics committee would have approved a study using oncolytic viruses for this third tumor because standard therapies typically work well. In this case, it would have been unethical to risk success with untested viral treatments.
Need for early intervention
Guy Ungerechts, a leading expert in oncolytic viruses in Germany who heads the Virotherapy Department at the National Center for Tumor Diseases in Heidelberg, says that early intervention is vital.
He has conducted more than 10 early clinical trials with various oncolytic viruses. “The patients I treat are severely ill,” he says. “They have undergone three or four chemotherapies and are often physically and psychologically exhausted.”
Clinical trials are often their last hope; ethics committees usually approve trials with new therapies only in such cases. And rarely in cases where the patients are still healthy enough for standard therapies to succeed because they see untested therapies as too risky.
The challenge with oncolytic virus therapy is that it must begin as early as possible to be effective because tumors learn over time how to evade the immune system. Additionally, during cancer treatment, the immune system loses strength — often due to prior chemotherapy — making late-stage clinical trials more likely to fail. The same treatment might succeed if applied earlier and could pave the way for significantly better therapies.
While there are studies where viruses have been used at earlier stages, they are rare. Therefore, individual cases like Halassy’s are invaluable for researchers as they provide initial insights into efficacy and underlying mechanisms — even though broad conclusions cannot be drawn from them.
Measles viruses against tumors
Halassy’s case is remarkable: she had spent years researching measles viruses and vesicular stomatitis viruses (VS viruses), which primarily infect hoofed animals and are related to rabies. Both types of viruses are known for effectively targeting tumor cells and have been used in clinical trials for this purpose.
Colleagues injected her with measles viruses first and then switched to VS viruses directly into the tumor.
Halassy only needed to propagate them at her institute; colleagues injected her with measles viruses first and then switched to VS viruses directly into the tumor when her body developed too much immunity against them.
After two months and ten injections, the tumor had softened and shrunk by nearly two-thirds; it was infiltrated by immune cells, while muscles and skin were no longer inflamed or infected. The tumor could then be surgically removed — an outcome also sought through chemotherapy. The viruses caused almost no side effects except mild fever and chills on some days.
The immune system can recognize and attack tumors, but not effectively enough by itself. The presence of these viruses enhanced the immune response by attracting immune cells into the tumor and destroying cancer cells while breaking their camouflage against the immune system — potentially catching cancer cells that were beginning to metastasize.
Individualized therapies
But how can genuine therapies be developed more quickly from such cases? Halassy emphasizes that her case does not imply that similar treatments would be universally effective; these viruses might only work for specific types of tumors or particular patient profiles — all of which needs systematic investigation.
Alena Buyx, a medical ethicist at TU Munich, agrees with Halassy regarding a fundamental issue in research: “The future of cancer treatment lies in personalized therapies — those tailored precisely to the genetic characteristics of a tumor and a patient’s situation.” In this sense, Halassy’s case could serve as an example.
“Individual therapies introduce a new fundamental problem in research ethics,” Buyx notes.
Traditionally, randomized controlled trials with many participants represent the gold standard in medical research: one group receives medication while another does not. If groups are large enough, results aren’t skewed by individual traits like lifestyle or pre-existing conditions since both groups will contain similar numbers of smokers or vegetarians.
New protocols
But how can research follow this principle when therapies are individualized? “If the hypothesis is that certain things work very well only for individual patients,” Buyx asks, “how can we study them while maintaining an evidence standard achievable only through many treatments?”
Innovative study formats must be considered.
Classical randomized studies often aren’t suitable here; innovative study formats must be considered — just like Beata Halassy did.
Her courageous self-experimentation evokes memories of medical pioneers: doctors and researchers who performed heart catheterizations on themselves or administered themselves vaccines or infections with pathogens — and some even won Nobel Prizes for their efforts.
While Halassy may not receive such accolades for her self-experimentation, she might pave the way for new treatment protocols in breast cancer development that otherwise would have taken much longer.
