Metastatic breast cancer represents one of the most complex forms of cancer, in which malignant cells spread beyond the primary tumor to distant organs and tissues. Although modern oncology has achieved significant progress, in approximately 40–60% of patients with metastatic breast cancer, standard treatment proves insufficiently effective or loses its efficacy over time. This makes the search for new treatment approaches, including immunotherapy, clinically significant.
New Immunotherapy Methods for Metastatic Breast Cancer
Treatment programs for stage 3 and stage 4 breast cancer may include several innovative immunotherapy methods aimed at addressing forms of the disease resistant to standard therapy. The protocols used are based on extensive research and clinical experience accumulated over several decades of practice.
This approach is used in various complex clinical situations, including triple-negative breast cancer, as well as cases of disease recurrence after standard treatment.
The choice of immunotherapeutic strategy depends on multiple factors, including the molecular characteristics of the tumor, previous treatment, the patient’s overall condition, and personal preferences. The decision regarding the use of immunotherapy is made on an individual basis after medical evaluation.
Oncolytic Virus Therapy for Metastatic Breast Cancer
Oncolytic viral therapy is one of the key components of the immunotherapeutic approach to metastatic breast cancer. Typically, this method is considered at early stages of treatment with the aim of reducing tumor mass and, in some cases, achieving minimal residual disease (MRD) status. A specialized intensive protocol, which is usually conducted over a limited period of time, is implemented in partner clinics that have appropriate permissions to use this method.
How Viral Therapy Works
Oncolytic viruses are capable of selectively finding and acting on tumor cells without damaging healthy tissues. During therapy, they:
- directly destroy cancer cells through selective viral replication within tumor cells;
- release tumor antigens that help the immune system recognize the tumor;
- transform immunologically “invisible” tumors into forms more accessible to immune response;
- create an inflammatory reaction that enhances the effect of subsequent treatment stages.
Compared to standard breast cancer treatment methods, an intensive course of oncolytic viral therapy provides more prolonged tumor exposure and immune system activation. In certain clinical situations, this method may be combined with direct intratumoral virus injection and photodynamic therapy.
Checkpoint Inhibitor Therapy
After completion of viral therapy, the use of checkpoint inhibitors may be considered as part of a comprehensive immunotherapeutic approach. Usually, this stage begins several weeks later, when the immune system becomes more sensitive to tumor cells previously “marked” by the virus.
In clinical practice, a low-dose checkpoint inhibitor protocol is used, which is characterized by the following features:
- reduction of factors that suppress the antitumor immune response;
- improved recognition of tumor cells by the immune system;
- less pronounced side effects compared to standard dosages;
- possibility of longer use due to better tolerability.
For patients with limited tolerance to standard checkpoint inhibitors, cytokine-mediated immunotherapy (CMI) may be recommended — a more affordable method that, in certain cases, can be administered at home under medical supervision.
The two-stage immunotherapy strategy is initially aimed at eliminating factors that prevent effective immune system function, and then at enhancing the antitumor immune response using targeted methods. In clinical practice, such a phased approach is associated with encouraging results, although treatment results may vary from patient to patient because every tumor is biologically different.
Personalized Anti-Cancer Vaccines for Breast Cancer
When cryopreserved tumor tissue is available, it is possible to create personalized anti-cancer vaccines based on the patient’s biomaterial. Tumor material collection can also be performed during planned surgical intervention. Such a personalized approach allows:
- development of a vaccine adapted to the unique tumor antigens of a specific patient;
- training the immune system to recognize and destroy residual cancer cells;
to increase the immunogenicity of tumor cells or their lysates through specialized processing, thereby rendering previously “cold” tumor cells more recognizable to the immune system;
to enhance the effectiveness of other immunotherapy modalities through synergistic interaction.
Anti-cancer vaccination is aimed at strengthening the immune system’s recognition of tumor-associated antigens and may be applied as part of an individualized immunotherapy protocol, particularly following surgical treatment or in the setting of minimal residual disease.
ATACK Therapy: Treatment with Donor Lymphocytes
The ATACK method (Allogeneic Targeted Activated Cancer Killer cells) uses specially prepared donor lymphocytes equipped with antibodies for targeted action against tumor cells. Donor immune cells are intentionally different from the patient’s cells, allowing them to recognize cancer cells as foreign and eliminate them.
ATACK therapy is aimed at forming a targeted immune response and may be particularly relevant in situations where the patient’s own immune system is weakened after chemotherapy or radiation therapy. Typically, this method is applied after preliminary reduction of tumor mass by other treatment methods, including upon achieving MRD status.
Photodynamic Therapy (PDT)
Within the framework of a comprehensive immunotherapeutic approach, photodynamic therapy (PDT) may be integrated with other treatment methods. Combined use of PDT:
- uses photosensitizers that selectively accumulate in tumor cells and are activated by light of a specific wavelength;
- leads to the formation of reactive oxygen species that damage tumor cells;
- stimulates local inflammatory reaction and immune response;
- enhances the action of oncolytic viruses and other immunotherapy components.
Photodynamic therapy is used both as a method of direct destruction of tumor foci and as a means of increasing the effectiveness of other therapeutic approaches. Depending on the location of metastases, PDT can be used both systemically and locally, which allows treatment to be adapted to specific clinical situations.
Who May Be Considered for Immunotherapy in Metastatic Breast Cancer?
Immunotherapy for metastatic breast cancer may be considered for patients who:
- have not achieved a clinically meaningful response to standard treatment approaches for metastatic breast cancer;
- are interested in modern experimental therapeutic strategies;
- have the ability to travel abroad to receive specialized treatment.
Depending on the individual characteristics of the disease, specific immunotherapy methods may be considered in the presence of the following factors:
- certain molecular and genetic tumor characteristics that may be taken into account when using oncolytic virus therapy or the ATACK method;
- tumor lesions that are potentially accessible for direct therapeutic intervention, when clinically justified;
- tumor material (fresh or cryopreserved) that, in selected cases, may be used for the development of a personalized anti-cancer vaccine.
How Each Case Is Evaluated
The preliminary assessment of the possibility of immunotherapy for metastatic breast cancer includes:
• a detailed analysis of previously administered treatment methods and their outcomes;
• review of imaging data (MRI, CT, PET-CT) to assess the extent and localization of the disease;
• evaluation of molecular and genetic testing results or recommendations for additional testing when necessary.
How Treatment Is Conducted
Immunotherapy programs for metastatic breast cancer generally include the following stages:
- an individual online consultation with Professor Shimon Slavin;
- treatment planning and development of a personalized therapeutic protocol;
- delivery of immunotherapy procedures for breast cancer in partner clinic in Germany, in line with local regulatory requirements;
- application of additional immunotherapy methods when medically indicated;
- in-person and remote patient follow-up and support.
Treatment involves coordination among several specialized medical centers to ensure a comprehensive and integrated approach.
International Patient Support
For patients traveling from other countries to receive treatment, the following support is provided:
- guidance and assistance throughout all stages of international treatment;
- support with medical travel arrangements;
- remote follow-up and support after returning home;
- coordination with local treating physicians for continued monitoring.
Next Steps
To determine whether immunotherapy for metastatic breast cancer may be considered in your case:
- complete the contact form on the website;
- submit medical records for preliminary review;
- schedule an individual consultation.
Each clinical case is reviewed on an individual basis. Immunotherapy programs for metastatic breast cancer may be of interest to patients who have already undergone standard treatment stages and are exploring additional therapeutic options.
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