Treatments that help fight Her2 cancer include rebuilding your microbiome and lymphocyte levels, reducing cancer stem cells, homocysteine and galectin-3, and using natural compounds and diet.
What is HER2?
HER2 (Human Epidermal Growth Factor Receptor 2) is a protein that helps regulate cell growth. When overexpressed, as in Her2 positive breast cancer, it drives uncontrolled cancer cell proliferation.
Targeted therapies such as trastuzumab (Herceptin), pertuzumab (Perjeta), ado-trastuzumab emtansine (Kadcyla), and trastuzumab deruxtecan (Enhertu) have dramatically improved outcomes. These drugs specifically block HER2 signaling or deliver chemotherapy directly to HER2-positive cells.
HER2 overexpression occurs in approximately 15–30% of breast cancers, 10–30% of gastric/gastroesophageal cancers and is currently being studied in other cancers such as ovarian.
The gut microbiome in Her2 +ve cancers
Researchers have found that response to Herceptin can be helped or hindered by the specific members of the gut microbiome.
Higher gut microbial diversity is associated with better response to Herceptin and patients who respond best to Herceptin show enrichment in beneficial bacterial members such as Clostridiales, Lachnospiraceae, Bifidobacteriaceae, and Turicibacteriaceae. Conversely, non-responders often have higher levels of Bacteroides species (1).
Indeed, in mice, giving microbiome members via a fecal transplant (FMT) from responders, improves response in non-responders.
Specific bacteria like Akkermansia muciniphila, Faecalibacterium prausnitzii, and Bifidobacterium members are linked to improved immune responses and treatment outcomes. Conversely, dysbiosis (gut imbalance from antibiotics, PPIs and previous chemotherapy or radiotherapy) and reduced microbial diversity are associated with resistance to HER2 therapy.
Experts suggest the gut microbiome is a potential target for improving HER2-positive breast cancer treatment through dietary interventions, probiotics or FMT.
The Tumour Microbiome in HER2 cancers
Studies indicate that Streptococcus and Balamuthia almost always found in HER2-positive tumours, with seven genera (Clostridium, PRD01a011B, Alloprevotella, Stakelama, Filibacter, Blastomonas, and Anaerostipes) significantly higher in HER2+ tumours compared to HER2- tumours (2).
Bacteria like Staphylococcus, carried by circulating tumor cells, can promote lung metastasis; and patients with recurrence show lower α-diversity and higher abundances of Sutterella and Ruminococcus, which correlate with poorer progression-free survival, especially in those with larger tumours.
Galectin-3 and HER2
Galectin-3 plays a significant role in HER2-positive breast cancer by promoting tumor malignancy, cancer stemness, and resistance to the targeted therapy Herceptin.
Galectin-3 enhances the proliferation, migration, invasion, and colony formation of HER2-positive breast cancer cells because it can activate the HER2 signaling pathway and upregulate EGFR, while also increasing the phosphorylation of key proteins like HER2, PI3K, AKT, and ERK1/2. It simultaneously downregulates the tumor suppressor PTEN.
Galectin-3 also activates the Notch1 signaling pathway, which upregulates cancer stem cell markers (e.g., CD44, Nanog, CD133) and promotes stemness, and Herceptin resistance (3).
Galectin-3 can be blocked by modified citrus pectin (MCP)
Herceptin and Lymphocytes
Herceptin has multiple effects against HER2 cancer, many involving lymphocytes. For example, Herceptin treatment enhances the ability of CD8+ cytotoxic T lymphocytes (CTLs) to recognize and kill HER2-overexpressing tumor cells (4).
Herceptin therapy also decreases the number of regulatory T cells (CD4+CD25+) in the peripheral blood of breast cancer patients; this is another positive benefit because these cells normally suppress immune responses.
The presence of cytotoxic Tumour Infiltrating Lymphocytes (TILs) in HER2-positive breast tumors is associated with improved prognosis and better response to therapy, including Herceptin.
While these factors enhance outcomes, it must be noted that the use of chemotherapy such as Docetaxel, or the use of antibiotics, or radiotherapy would significantly suppress lymphocyte levels.
Cancer Stem Cells (CSCs) and HER2 cancers
Cancer stem cells (CSCs), a small subset of tumor cells with self-renewal capabilities, are strongly implicated in treatment resistance and cancer recurrence. Altered HER2 signaling plays a key role in maintaining and enriching breast cancer stem cells (BCSCs), interacting with critical stemness pathways like Notch and Wingless/β-catenin. This enhances tumour aggression, metastasis, and therapy resistance (5).
Ivermectin and HER2 cancer
Ivermectin shows potential in treating HER2-positive breast cancer, primarily through its ability to inhibit HSP27 (heat shock protein 27), a protein linked to treatment resistance.
Research indicates that ivermectin inhibits HSP27-regulated signaling pathways, including those involving HER2, which is overexpressed in HER2-positive breast cancers. By blocking HSP27, ivermectin can reduce the activity of HER2 and its downstream effectors like AKT and MAPK, potentially overcoming resistance to targeted therapies such as trastuzumab (6).
In preclinical models, ivermectin has demonstrated synergistic effects when combined with HER2-targeted drugs, enhancing their anticancer activity. It also suppresses epithelial-to-mesenchymal transition (EMT)—a process linked to metastasis—by modulating key markers like E-cadherin, vimentin, and Snail, which are relevant in aggressive HER2-positive and triple-negative subtypes.
Homocysteine and HER2 cancer
Elevated homocysteine levels are associated with increased risk for certain breast cancer subtypes, including HER2-positive disease. A study found that high thiamine (vitamin B1) intake was specifically linked to a lower risk of HER2+ breast cancer, suggesting a potential protective role of one-carbon metabolism vitamins (7).
Folate (B-9), riboflavin (B-2), cobalamin (b-12) and vitamin B6 are also associated with reduced risk of other breast cancers but not HER2+ disease.
While homocysteine itself may not be a direct causal factor for HER2+ cancer, disturbances in homocysteine metabolism—particularly due to low folate or B vitamin status—can contribute to DNA hypomethylation, genomic instability, and altered estrogen metabolism, which may promote tumorigenesis in hormone-sensitive cancers, including HER2+ breast cancer. Homocysteine levels build before most chronic illnesses (dementia, cardiovascular) not just cancer.
Berberine reduces homocysteine, as does turmeric; and research from Professor David Smith at Oxford University showed the combination of a fish oil and a B complex could strongly reduce homocysteine levels. An MTHFR mutation can lie behind high homocysteine levels (8).
Beta glucan and HER2 cancer
Beta-glucan has shown potential in targeting HER2-positive (HER2+) breast cancer through multiple mechanisms, both direct and immune-mediated. Studies indicate that certain beta-glucans can directly inhibit HER2+ breast cancer cells. For example, a beta glucan (BDG16) from Agaricus mushrooms has cytotoxic properties and has been shown to directly inhibit HER2 cancer cells (9).
Preclinical studies show that co-administering beta-glucan with Herceptin enhances tumour cell killing in vivo, potentiating the therapeutic effect of the antibody (10).
Other natural Compounds that attack HER2 cancer
There are foods and supplements that help with this. For example - Anthocyanins (purple aubergines, plums, cherries, blue berries, blackberries, raspberries, red cabbage, red onions, black rice), Psoralen (figs, celery, parsley, carrots), Beta-glucan (medicinal mushrooms, mother's milk, oats, broccoli, seaweed), Olive oil and Turmeric.
Other natural compounds such as Apigenin (high in oregano oil), Melatonin, Turmeric, Quercetin, and Berberine also have research showing they help fight HER2 cancer.
Genistein (from soy): Inhibits HER2 activation, promotes apoptosis, and restores estrogen receptor expression, potentially improving treatment response.
Sulforaphane (from broccoli sprouts): Increases chemosensitivity, induces apoptosis, and downregulates HER2-related signaling pathways.
Epigallocatechin gallate (EGCG) (from green tea): Suppresses HER2 signaling, promotes apoptosis, and enhances the effects of chemotherapy and radiation.
We have an article on 8 natural compounds that can help fight HER2 cancer.
The number one Ayurvedic herb Tulsi (Holy Basil) has been shown to kill cancer cells and cancer stem cells in Pancreatic and prostate cancer particularly when curcumin and resveratrol are added. There is some evidence that it can do the same with HER2 cancer (11).
Adopting a Rainbow Diet, with its extra virgin olive oils and over 500 polyphenols, has been shown to reduce the risk of HER2 breast cancer; while a diet high in saturated fat increases risk (12).
Oleic acid, the main monounsaturated fatty acid in olive oil, suppresses Her-2/neu (erbB-2) expression and synergistically enhances the growth-inhibitory effects of Herceptin in HER2 breast cancer cells. Oleuropein aglycone, the bitter principle of olive oil, is among the most potent phenolic compounds in extra virgin olive oil for reducing breast cancer cell viability. It induces strong tumoricidal effects in HER2-positive cells by promoting proteasomal degradation of the HER2 protein, reducing its activation, and enhancing the efficacy of trastuzumab. Notably, it can reverse acquired resistance to Herceptin, restoring drug sensitivity in resistant cancer cells.
Olive oil polyphenols, particularly oleuropein aglycone and hydroxytyrosol, show strong potential in reducing the risk of HER2-positive breast cancer recurrence through multiple mechanisms (13).
Why not ask Chris Woollams to prepare you a Personal Programme?
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Go to: The crucial role of Lymphocytes in cancer
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References:
1.The Relationship Between Microbial Community and Breast Cancer; Xuelian Song, Changran Wei, Xiangqi Li; Front Cell Infect Microbiol. 2022 Jun 16;12:849022
2. The Role of The Tumor Microbiome in Tumor Development and Its Treatment; Yan Chen et al; Front Immunol. 2022 Jul 15;13:935846.
3. Galectin-3 enhances trastuzumab resistance by regulating cancer malignancy and stemness in HER2-positive breast cancer cells; Yugiu Chen et all; Thoracic Cancer, 22 May 2022
4. Herceptin Enhances the Antitumor Effect of Natural Killer Cells on Breast Cancer Cells Expressing Human Epidermal Growth Factor Receptor-2; Xiao Tian et al; Front Immunol. 2017 Oct 30:8:1426.
5. HER2 Signaling and Breast Cancer Stem Cells: The Bridge behind HER2-Positive Breast Cancer Aggressiveness and Therapy Refractoriness; Serenella M Pupa et al; Cancers (Basel). 2021 Sep 24;13(19):4778.
6. Ivermectin inhibits HSP27 and potentiates efficacy of oncogene targeting in tumor models; Lucia Nappi et al, JCI Oncology
7. Micronutrients Involved in One-Carbon Metabolism and Risk of Breast Cancer Subtypes; Ilaria Cancarini et al; Plos One 10(9) September 16 2015
8. MTHFR gene mutations and chronic illness - https://chriswoollamshealthwatch.com/your-illness/mthfr-gene-mutations-and-chronic-illness/
9. Anti-Cancer Potential of Linear β-(1→6)-D-Glucan from Agaricus bisporus on Estrogen Receptor-Positive (ER+) Breast Cancer Cells; Renata Rutckeviski et al; MDPI Molecules 19 Oct 2024, 29(19), 4781
10. Beta glucan induces proliferation and activation of monocytes in peripheral blood of patients with advanced breast cancer; Gokhan Demir et al; International Immunopharmacology, Volume 7, Issue 1, January 2007, Pages 113-116
11. In Vitro and In Vivo Anticancer Activity of Basil (Ocimum spp.): Current Insights and Future Prospects; Simone Perna et al; Cancers 11 May 2022, 14(10), 2375;
12. Nine major health benefits of Extra Virgin Olive Oil - https://the-rainbow-diet.com/articles/the-colourful-mediterranean-diet/the-rainbow-diet-and-olive-oil/
13. Olive oil intake and cancer risk: A systematic review and meta-analysis; Christos Markellos et al; PLoS One. 2022 Jan 11;17(1):e0261649