Personalized mRNA Vaccine Shows Promise Against Aggressive Breast Cancer

For years, oncologists have distinguished between “hot” and “cold” tumors. Hot tumors are those readily detected and potentially combatted by the body’s immune system. Recent advances in immunotherapy – treatments that amplify the immune system’s ability to locate and destroy tumor cells – have dramatically improved outcomes for many cancers. However, a significant challenge remains: how to “heat up” cold tumors, those that evade immune detection and resist treatment. One promising strategy involves vaccination.

A New Approach to Triple-Negative Breast Cancer

Preliminary results released this week detail a vaccine targeting triple-negative breast cancer, a historically “cold” tumor due to its resistant genetic and molecular profile. This aggressive subtype disproportionately affects younger women and is prone to recurrence, often within the first three years after initial treatment. While breast cancer is the most common cancer in women, triple-negative accounts for approximately 15% of all cases. Researchers are also exploring similar vaccine approaches for even more complex cancers, such as pancreatic cancer.

Personalized mRNA Vaccines Show Promise

The experimental treatment utilizes a personalized mRNA vaccine, designed specifically for each patient’s tumor. Administered alongside existing therapies, ideally during early stages of the disease, initial trials have shown positive responses in the majority of participants. Of the 14 women treated, 11 experienced complete responses and have remained cancer-free for six years, according to findings published in Nature.

These immunizations are created after sequencing a patient’s tumor genome. Scientists select up to 20 proteins unique to the cancer – called neoantigens – and formulate an mRNA vaccine containing instructions for the body to produce T lymphocytes (white blood cells) capable of identifying, remembering, and destroying malignant cells. The goal is to bolster the immune system’s ability to fight the tumor and prevent future recurrences.

The Team Behind the Breakthrough

The lead authors of this work are Özlem Türeci and Uğur Şahin, a husband-and-wife team of immunologists and co-founders of the pharmaceutical company BioNtech. The German company gained prominence during the COVID-19 pandemic for developing one of the most effective vaccines against the virus.

The key takeaway from these results is that a personalized vaccine, tailored to each patient, is “viable in a clinical context” and elicits an immune response in most patients.

Cautious Optimism

Despite the encouraging data, Türeci and Şahin emphasize caution. Şahin notes the results from the 11 patients are “promising,” but require careful interpretation. “Phase 1 trials are small by definition and lack a control group, so we cannot definitively attribute the results to the vaccine,” he stated.

While five years of remission is often considered indicative of a cure by oncologists, Türeci stresses the need for further research. “To speak of a cure requires more extensive, controlled databases and longer follow-up periods,” she explains. “What we observe can be described as a promising long-term follow-up free of recurrence, rather than proof of a cure. It’s important not to overestimate these preliminary results, especially as there is currently no follow-up trial in triple-negative breast cancer where patients can access this unapproved treatment.”

These findings add to other initial successes against difficult-to-treat tumors, according to Türeci and Şahin. A similar mRNA vaccine developed by BioNtech for melanoma, a “hot” tumor, has shown promising results in more advanced trials. The team has also created an immunization for pancreatic cancer – traditionally a “cold” tumor – with up to 50% of patients responding by generating cancer-killing white blood cells, a response linked to improved prognosis.

BioNtech is currently conducting Phase 2 trials with mRNA vaccines for colon, pancreatic, and bladder cancers. Depending on these results, expected later this year, the company will decide whether to initiate Phase 2 trials for the triple-negative breast cancer vaccine. Successful completion of these phases would necessitate a third, larger trial to definitively demonstrate efficacy. “Our vision is that by 2030, a personalized mRNA cancer vaccine will be approved,” Türeci states.

Ignacio Melero, director of Immunology and Immunotherapy at Cima Universidad de Navarra, described the study as “very interesting” for its thorough examination of the immune response in patients undergoing neoadjuvant treatment for localized triple-negative breast cancer.

Isabel Echavarría, scientific secretary of the Spanish Society of Medical Oncology (SEOM), agrees that “vaccines against cancer are a promising strategy.” She notes that studies like this demonstrate the ability to develop a specific immune response against tumor antigens. However, she emphasizes the need for randomized clinical trials to prove a clinically significant benefit over standard therapy, while also acknowledging the challenges of cost and development time associated with personalized vaccine production.

Frequently Asked Questions

What is the difference between a “hot” and “cold” tumor?

“Hot” tumors are those that the immune system can detect and potentially fight. “Cold” tumors evade immune detection and are more resistant to treatment.

What is mRNA vaccine technology?

mRNA vaccines contain instructions for the body to produce proteins that trigger an immune response. In this case, the vaccine instructs the body to create T lymphocytes that can identify and destroy cancer cells.

How long have patients in the trial remained cancer-free?

Eleven of the 14 women treated in the initial trial have remained cancer-free for six years.

What role do you think personalized medicine will play in the future of cancer treatment?