In Vitro Anticancer Efficacy of Metformin Combination Therapy in Breast Cancer: A Systematic Review
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Abstract
Metformin, a widely used antidiabetic drug, has attracted increasing interest as a potential anticancer agent owing to its ability to modulate cellular metabolism and oncogenic signaling pathways. This systematic review evaluated the in vitro anticancer efficacy of metformin-based combination therapies in breast cancer, focusing on synergistic activity, molecular mechanisms, and subtype-specific responses. A systematic search of the Scopus database was conducted in accordance with PRISMA 2020 guidelines, resulting in the inclusion of 23 eligible studies published between 2016 and May 2026. The studies investigated combinations of metformin with chemotherapeutic agents, targeted therapies, repurposed drugs, and natural compounds across estrogen receptor-positive (ER+), HER2-positive, and triple-negative breast cancer (TNBC) cell lines. Most combinations demonstrated synergistic or potentiating effects, characterized by enhanced apoptosis, cell-cycle arrest, metabolic disruption, and inhibition of tumor-promoting signaling pathways. Mechanistically, recurrent modulation of the AMPK/mTOR, PI3K/Akt, MAPK/ERK, and mitochondrial bioenergetic networks was observed across multiple therapeutic combinations. Several studies also reported reversal of drug resistance, suppression of cancer stemness, and inhibition of epithelial–mesenchymal transition-associated phenotypes. However, the interpretation and translational relevance of these findings are limited by the widespread use of supra-physiological metformin concentrations and considerable methodological heterogeneity among studies. Overall, the available evidence supports metformin as a metabolic sensitiser capable of enhancing the efficacy of diverse anticancer agents in breast cancer models. Future research should prioritize clinically relevant exposure conditions, advanced in vitro models, and predictive biomarker development to facilitate translational application.
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References
I. Sung H, Ferlay J, Siegel RL, Laversanne M, Soerjomataram I, Jemal A, Bray F. Global cancer statistics 2020: GLOBOCAN estimates of incidence and mortality worldwide for 36 cancers in 185 Countries. CA Cancer J Clin 2021;71:209–49. https://doi.org/10.3322/caac.21660.
II. Freihat O, Sipos D, Kovacs A. Global burden and projections of breast cancer incidence and mortality to 2050: a comprehensive analysis of GLOBOCAN data. Front Public Heal 2025;13:1622954. https://doi.org/10.3389/fpubh.2025.1622954.
III. Wang J, Wu S-G. Breast Cancer: An Overview of Current Therapeutic Strategies, Challenge, and Perspectives. Breast Cancer (Dove Med Press 2023;15:721–30. https://doi.org/10.2147/BCTT.S432526.
IV. Eapen JV, George P, Thomas S, Antony J. Integrative strategies in breast cancer therapy: Conventional approaches, emerging advances, and future challenges. ASPET Discov 2025;1:100012. https://doi.org/https://doi.org/10.1016/j.aspetd.2025.100012.
V. Recino A, Rayner MLD, Rohn JL, Della Pasqua O, Recino A, Rayner MLD, Rohn JL, Carter B, Cupani A, Dahlmann-Noor A, Foltynie T, Furman J, Hobbiger S, Lugarà E, Mole SE, Orlu M, Phillips JB, Spingardi P, Pasqua O Della. Therapeutic innovation in drug repurposing: Challenges and opportunities. Drug Discov Today 2025;30:104390. https://doi.org/https://doi.org/10.1016/j.drudis.2025.104390.
VI. Foretz M, Guigas B, Viollet B. Metformin: update on mechanisms of action and repurposing potential. Nat Rev Endocrinol 2023;19:460–76. https://doi.org/10.1038/s41574-023-00833-4.
VII. Zeljković V, Bogavac M, Dekić M, Minić S, Mahmutović E, Kunkin V, Marković Z, Karaman M. Molecular Insights into the Interaction Between Metformin and Caffeine: The Time-Dependent Antagonism and Modulation of p53 Signaling in Cancer Cells. Molecules 2026;31. https://doi.org/10.3390/molecules31111877.
VIII. Luo Q, Hu D, Hu S, Yan M, Sun Z, Chen F. In vitro and in vivo anti-tumor effect of metformin as a novel therapeutic agent in human oral squamous cell carcinoma. BMC Cancer 2012;12:517. https://doi.org/10.1186/1471-2407-12-517.
IX. Shah S, Mansour HM, Aguilar TM, Lucke-Wold B. Advances in Anti-Cancer Drug Development: Metformin as Anti-Angiogenic Supplemental Treatment for Glioblastoma. Int J Mol Sci 2024;25. https://doi.org/10.3390/ijms25115694.
X. Barbosa F, Cunha A, Barbosa J, Faria J, Queirós O. The Dual Role of Metformin: Repurposing an Antidiabetic Drug for Cancer Therapy. Appl Sci 2025;15. https://doi.org/10.3390/app152111576.
XI. Alim R, Akalanka HMK. Metformin and its derivatives in breast cancer: from glycaemic control to tumor-intrinsic pathways. Breast Cancer Res 2025;28:13. https://doi.org/10.1186/s13058-025-02194-4.
XII. Galal MA Al-Rimawi M HADHASAA. Metformin: A Dual-Role Player in Cancer Treatment and Prevention. 2024. https://doi.org/10.3390/ijms25074083.
XIII. Feng J-L, Qin X. Metformin and cancer-specific survival among breast, colorectal, or endometrial cancer patients: A nationwide data linkage study. Diabetes Res Clin Pract 2021;175:108755. https://doi.org/https://doi.org/10.1016/j.diabres.2021.108755.
XIV. Galal MA, Al-Rimawi M, Hajeer A, Dahman H, Alouch S, Aljada A. Metformin: A Dual-Role Player in Cancer Treatment and Prevention. Int J Mol Sci 2024;25.
https://doi.org/10.3390/ijms25074083.
XV. Amengual-Cladera E, Morla-Barcelo PM, Morán-Costoya A, Sastre-Serra J, Pons DG, Valle A, Roca P, Nadal-Serrano M. Metformin: From Diabetes to Cancer-Unveiling Molecular Mechanisms and Therapeutic Strategies. Biology (Basel) 2024;13. https://doi.org/10.3390/biology13050302.
XVI. Khan SS, Rangraze IR, Wali AF, Jhancy M, Attia RA, Elshamly HAH, Adam S, Elbeshbeishy RAM. Repurposing Metformin in Precision Oncology: Mechanistic Insights, Biomarker-Guided Strategies, and Translational Imperatives. Medicina (B Aires) 2025;61.
https://doi.org/10.3390/medicina61091577.
XVII. Lv H, Gong H, Zhao R, Gao X, Liu W, Zhao L, Sun R. From basics to clinics: New opportunities for metformin in tumor metabolic intervention and treatment. Biomed Pharmacother 2025;191:118507. https://doi.org/https://doi.org/10.1016/j.biopha.2025.118507.
XVIII. Shamahmood MN, Miri A, Yousefi MJ, Mezginejad F. Therapeutic potential of metformin-based combination therapy in acute myeloid leukemia. Discov Oncol 2025;17:12. https://doi.org/10.1007/s12672-025-04205-4.
XIX. Zhu L, Yang K, Ren Z, Yin D, Zhou Y. Metformin as anticancer agent and adjuvant in cancer combination therapy: Current progress and future prospect. Transl Oncol 2024;44:101945. https://doi.org/10.1016/j.tranon.2024.101945.
XX. Thyagarajan A, Gajjar V, Sahu RP. Are metformin-based combination approaches beneficial for non-small cell lung cancer: evidence from experimental and clinical studies. Mil Med Res 2025;12:61. https://doi.org/10.1186/s40779-025-00649-5.
XXI. Deng J, Peng M, Wang Z, Zhou S, Xiao D, Deng J, Yang X, Peng J, Yang X. Novel application of metformin combined with targeted drugs on anticancer treatment. Cancer Sci 2019;110:23–30. https://doi.org/10.1111/cas.13849.
XXII. Peng M, Darko KO, Tao T, Huang Y, Su Q, He C, Yin T, Liu Z, Yang X. Combination of metformin with chemotherapeutic drugs via different molecular mechanisms. Cancer Treat Rev 2017;54:24–33. https://doi.org/https://doi.org/10.1016/j.ctrv.2017.01.005.
XXIII. Hosseini SA, Valadbeigi H, Khoshnazar SM, Khoshnood S, Falahi S, Rezaee D, Hematian A, Haddadi MH. Metformin as a Multifaceted Therapeutic Agent for Gastrointestinal Diseases: Mechanisms, Clinical Efficacy, and Future Directions. Pharmacol Res Perspect 2026;14:e70257. https://doi.org/https://doi.org/10.1002/prp2.70257.
XXIV. Lee JO, Kang MJ, Byun WS, Kim SA, Seo IH, Han JA, Moon JW, Kim JH, Kim SJ, Lee EJ, In Park S, Park SH, Kim HS. Metformin overcomes resistance to cisplatin in triple-negative breast cancer (TNBC) cells by targeting RAD51. Breast Cancer Res 2019;21. https://doi.org/10.1186/s13058-019-1204-2.
XXV. Li Y, Wang M, Zhi P, You J, Gao J. Metformin synergistically suppress tumor growth with doxorubicin and reverse drug resistance by inhibiting the expression and function of P-glycoprotein in MCF7/ADR cells and xenograft models. Oncotarget 2018;9:2158–74. https://doi.org/10.18632/oncotarget.23187.
XXVI. Kheraldine H, Hassan AF, Saeed S, Merhi M, Mateo JM, Ulamec M, Peric-Balja M, Vranic S, Al-Thawadi H, Moustafa A-EA. Neratinib and metformin: A novel therapeutic approach against HER2-Positive Breast Cancer. Biomed Pharmacother 2025;187. https://doi.org/10.1016/j.biopha.2025.118034.
XXVII. Shi Y, Niu P, Cheng Q, Chen L, Weng Y, Yang X. Metformin enhances alpelisib sensitivity in HER2+ breast cancer by suppressing cancer stemness and oncogenic signaling. Front Oncol 2025;15. https://doi.org/10.3389/fonc.2025.1631415.
XXVIII. Xue L, Chen F, Yue F, Camacho L, Kothapalli S, Wei G, Huang S, Mo Q, Ma F, Li Y, Jiralerspong S. Metformin and an insulin/IGF-1 receptor inhibitor are synergistic in blocking growth of triple-negative breast cancer. Breast Cancer Res Treat 2021;185:73–84. https://doi.org/10.1007/s10549-020-05927-5.
XXIX. Zhang Z, Zeng D, Zhang W, Chen A, Lei J, Liu F, Deng B, Zhuo J, He B, Yan M, Lei X, Wang S, Lam EW-F, Liu Q, Wang Z. Modulation of oxidative phosphorylation augments antineoplastic activity of mitotic aurora kinase inhibition. Cell Death Dis 2021;12. https://doi.org/10.1038/s41419-021-04190-w.
XXX. Gu Z, Ye F, Luo H, Li X, Gong Y, Mao S, Jia X, Han X, Han B, Fu Y, Cheng X, Li J, Shao Z, Wen P, Hu X, Zhuang Z. Metformin sensitizes triple-negative breast cancer to histone deacetylase inhibitors by targeting FGFR4. J Biomed Sci 2025;32. https://doi.org/10.1186/s12929-025-01129-7.
XXXI. Ariaans G, Jalving M, de Vries EGE, de Jong S. Anti-tumor effects of everolimus and metformin are complementary and glucose-dependent in breast cancer cells. BMC Cancer 2017;17. https://doi.org/10.1186/s12885-017-3230-8.
XXXII. Wang K, Huang J. Combination of oxabicycloheptene sulfonate (OBHS) and antidiabetic drugs synergistically inhibits proliferation in human breast cancer cells. Oncologie 2025;27:57–69. https://doi.org/10.1515/oncologie-2024-0471.
XXXIII. Liu J, Wang H, Zhang M, Li Y, Wang R, Chen H, Wang B, Gao X, Song S, Wang Y, Ren Y, Li J, Liu P. Metformin and simvastatin synergistically suppress endothelin 1-induced hypoxia and angiogenesis in multiple cancer types. Cancer Sci 2023;114:640–53. https://doi.org/10.1111/cas.15602.
XXXIV. Rico M, Baglioni M, Bondarenko M, Laluce NC, Rozados V, André N, Carré M, Scharovsky OG, Márquez MM. Metformin and propranolol combination prevents cancer progression and metastasis in different breast cancer models. Oncotarget 2017;8:2874–89. https://doi.org/10.18632/oncotarget.13760.
XXXV. Cheng G, Zielonka J, Hardy M, Ouari O, Chitambar CR, Dwinell MB, Kalyanaraman B. Synergistic inhibition of tumor cell proliferation by metformin and mito-metformin in the presence of iron chelators. Oncotarget 2019;10:3518–32. https://doi.org/10.18632/oncotarget.26943.
XXXVI. Wu Y, Lyu H, Tan C, Larsen ME, Tang S-C, Huang S, Liu B. Synergistic anti-tumor activity of ciclopirox olamine and metformin in triple-negative breast cancer. Genes Dis 2026;13. https://doi.org/10.1016/j.gendis.2025.101538.
XXXVII. Hosseini SS, Askari N, Yaghoobi MM. Combined anti-tumor effects of metformin and azacitidine in breast cancer cells. BMC Cancer 2025;25. https://doi.org/10.1186/s12885-025-14908-0.
XXXVIII. Long L, Hu X, Li X, Zhou D, Shi Y, Wang L, Zeng H, Yu X, Zhou W. The anti-breast cancer effect and mechanism of Glimepiride-Metformin adduct. Onco Targets Ther 2020;13:3777–88. https://doi.org/10.2147/OTT.S240252.
XXXIX. Wawszczyk J, Wolan R, Kapral M, Orchel A. Anticancer Activity Of Melatonin and Metformin Alone and In Combination Against Melanoma and Breast Cancer Cells. Acta Pol Pharm - Drug Res 2024;81:767–83. https://doi.org/10.32383/appdr/197350.
XL. Zhao M, Wang Y, Du C, Liu Y, Zhang N, Luo F. Aspirin and metformin exhibit antitumor activity in murine breast cancer. Oncol Rep 2018;39:1414–22. https://doi.org/10.3892/or.2018.6190.
XLI. Xin M, Wang Y, Ren Q, Guo Y. Formononetin and metformin act synergistically to inhibit growth of MCF-7 breast cancer cells in vitro. Biomed Pharmacother 2019;109:2084–9. https://doi.org/10.1016/j.biopha.2018.09.033.
XLII. Chatran M, Pilehvar-Soltanahmadi Y, Dadashpour M, Faramarzi L, Rasouli S, Jafari-Gharabaghlou D, Asbaghi N, Zarghami N. Synergistic anti-proliferative effects of metformin and silibinin combination on T47D breast cancer cells via hTERT and cyclin D1 inhibition. Drug Res (Stuttg) 2018;68:710–6. https://doi.org/10.1055/a-0631-8046.
XLIII. Falah RR, Talib WH, Shbailat SJ. Combination of metformin and curcumin targets breast cancer in mice by angiogenesis inhibition, immune system modulation and induction of p53 independent apoptosis. Ther Adv Med Oncol 2017;9:235–52. https://doi.org/10.1177/1758834016687482.
XLIV. Salim EI, Alabasy MM, Nashar EME, Al-Zahrani NS, Alzahrani MA, Guo Z, Beltagy DM, Shahen M. Molecular interactions between metformin and D-limonene inhibit proliferation and promote apoptosis in breast and liver cancer cells. BMC Complement Med Ther 2024;24. https://doi.org/10.1186/s12906-024-04453-x.
XLV. Wokoun U, Hellriegel M, Emons G, Gröndker C. Co-Treatment of breast cancer cells with pharmacologic doses of 2-deoxy-D-glucose and metformin: Starving tumors. Oncol Rep 2017;37:2418–24. https://doi.org/10.3892/or.2017.5491.
XLVI. Mahmoudi G, Ehteshaminia Y, Kokhaei P, Jalali SF, Jadidi-Niaragh F, Pagheh AS, Enderami SE, Kenari SA, Hassannia H. Enhancement of targeted therapy in combination with metformin on human breast cancer cell lines. Cell Commun Signal 2024;22. https://doi.org/10.1186/s12964-023-01446-0.