Metformin and Cancer: Solutions to a Real-World Evidence Failure

Effect of SGLT2i on kidney outcomes of individuals with type 2 diabetes according to body mass index: nationwide cohort study

AIMS

To investigate the clinical significance of the modification of the kidney protective effects of sodium-glucose cotransporter-2 (SGLT2) inhibitors by baseline body mass index (BMI).

METHODS AND RESULTS

We included individuals with SGLT2 inhibitors or dipeptidyl peptidase-4 (DPP4) inhibitors newly prescribed for type 2 diabetes using a nationwide epidemiological cohort and performed propensity score matching (1:2). The primary outcome was the annual eGFR decline, assessed using a linear mixed-effects model, compared between individuals with SGLT2 inhibitors and DPP4 inhibitors. We investigated the interaction effect of BMI at the time of prescription using a three-knot restricted cubic spline model. We analysed 2165 individuals with SGLT2 inhibitor prescriptions and 4330 individuals with DPP4 inhibitor prescriptions. Overall, the annual decline in eGFR was less pronounced in the group treated with SGLT2 inhibitors than in those treated with DPP4 inhibitors (-1.34 mL/min/1.73 m2 vs. -1.49 mL/min/1.73 m2). The advantage of SGLT2 inhibitors in mitigating eGFR decline was augmented in the individuals with higher BMI (P-value for interaction 0.0017). Furthermore, even upon adjusting the definition of outcomes to encompass a 30 or 40% reduction in eGFR, the potential advantages of SGLT2 inhibitors over DPP4 inhibitors persisted, with a trend of augmented effects with higher BMI. This interaction effect was evident in the individuals with preserved kidney function.

CONCLUSION

Our nationwide epidemiological study substantiated the improved kidney outcomes in the SGLT2 inhibitor users compared with the DPP4 inhibitor users across a wide range of BMI, which was pronounced for individuals with higher BMI.

Carbohydrate kinase inhibition: a promising strategy in cancer treatment

Carbohydrate kinases (CKs) are pivotal in various biological processes, including energy consumption, cell signaling, and biosynthesis. They are a group of enzymes that facilitate the phosphorylation of carbohydrates, playing a crucial role in cellular metabolism. These enzymes facilitate the transfer of a phosphate group from a high-energy donor like ATP to a specified location on a carbohydrate substrate. Dysregulated kinase activity drives tumor growth and progression. Inhibitors targeting these enzymes have been developed and used in cancer therapy. The CK family encompasses three major types: hexokinases, ribokinases, and phosphatidylinositol kinases, with inhibitors of paramount importance in cancer treatment. This review explores the role of CKs in cancer and its inhibitors, providing insights into improving existing inhibitors and designing new ones.

Metformin for Treating Gestational Diabetes: What Have We Learned During the Last Two Decades? A Systematic Review

There has been accumulating evidence over the past two decades that metformin can be an effective treatment for gestational diabetes mellitus (GDM) in women whose diet and exercise fail to attain optimal glycemic control. The objective of this review was to comprehensively analyze all studies investigating the effectiveness of metformin compared to insulin and other drugs utilized for the treatment of GDM. After a comprehensive literature review based on PRISMA 2020, 35 studies were included after a selection process utilizing predetermined inclusion and exclusion criteria. A variety of short-term maternal and neonatal outcomes were assessed. Metformin is a highly efficient medication for attaining optimal control of blood sugar levels in women with GDM, resulting in a significant reduction in the amount of weight gained during pregnancy. Regarding additional maternal outcomes, such as pregnancy-induced hypertension and cesarean deliveries, some studies demonstrate a link between metformin and a reduced occurrence of both conditions. In contrast, others do not find an association. Regarding short-term neonatal outcomes, metformin does not exhibit any changes in gestational age at delivery. In contrast, metformin demonstrated substantial decreases in the likelihood of greater gestational birth weight and neonatal hospitalization when compared to other drugs. When compared primarily to insulin, metformin decreases the probability of several short-term outcomes related to pregnancy and newborns. Additional data are necessary for extended follow-up studies, including patients with GDM treated with metformin.

Metformin and the risk of malignant tumors of digestive system: a mendelian randomization study

BACKGROUND

Observational studies suggest that metformin may reduce the risk of malignant tumors of the digestive system (MTDS), but these findings are often confounded by bias and unmeasured variables. Recent meta-analyses have questioned these associations, emphasizing the need for robust causal inference.

METHODS

Mendelian randomization (MR) was used to evaluate the causal relationship between metformin and MTDS. Genetic variants associated with metformin's molecular targets were selected from GTEx, eQTLGen, and UK Biobank and validated using genetic colocalization to ensure instrument validity. GWAS summary statistics for MTDS, encompassing up to 314,193 controls and 6,847 colorectal cancer cases, were obtained from FinnGen and EBI. The primary analysis employed the inverse-variance weighted (IVW) method, supplemented by MR-Egger, weighted median, and weighted mode analyses. Bonferroni correction was applied to adjust for multiple testing across 14 cancer types.

RESULTS

Genetically proxied metformin use was associated with an increased risk of colorectal cancer (OR = 2.38, 95%CI = 1.38-4.09, P = 0.0018) and related subtypes. No causal relationship was found for hepatocellular carcinoma, gastric cancer, pancreatic cancer, or other digestive system cancers. The robustness of these findings was supported by sensitivity analyses, which indicated no significant pleiotropy, and leave-one-out tests.

CONCLUSION

This study provides robust genetic evidence that metformin use increases the risk of colorectal cancer, challenging its role as a preventive agent for digestive cancers. These findings emphasize the need for clinicians to carefully evaluate the risks and benefits of metformin, particularly in populations at higher risk for colorectal cancer. Future research should focus on delineating the mechanisms underlying this association to optimize the use of metformin in clinical practice.

Risk of Incident Cancer in Veterans with Diabetes Who Use Metformin Versus Sulfonylureas

Prior research suggests metformin has anti-cancer effects, yet data are limited. We examined the association between diabetes treatment (metformin versus sulfonylurea) and risk of incident diabetes-related and non- diabetes-related cancers in US veterans. This retrospective cohort study included US veterans, without cancer, aged ≥ 55 years, who were new users of metformin or sulfonylureas for diabetes between 2001 to 2012. Cox proportional hazards models, with propensity score-matched inverse probability of treatment weighting (IPTW) were constructed. A total of 88,713 veterans (mean age 68.6 ± 7.8 years; 97.7% male; 84.1% White, 12.6% Black, 3.3% other race) were followed for 4.2 ± 3.0 years. Among metformin users (n = 60,476), there were 858 incident diabetes-related cancers (crude incidence rate [IR; per 1,000 person-years] = 3.4) and 3,533 non-diabetes-related cancers (IR = 14.1). Among sulfonylurea users (n = 28,237), there were 675 incident diabetes-related cancers (IR = 5.5) and 2,316 non-diabetes-related cancers (IR = 18.9). After IPTW adjustment, metformin use was associated with a lower risk of incident diabetes-related cancer (hazard ratio [HR] = 0.66, 95% CI 0.58-0.75) compared to sulfonylurea use. There was no association between treatment group (metformin versus sulfonylurea) and non-diabetes-related cancer (HR = 0.96, 95% CI 0.89-1.02). Of diabetes-related cancers, metformin users had lower incidence of liver (HR = 0.39, 95% CI 0.28-0.53), colorectal (HR = 0.75, 95% CI 0.62-0.92), and esophageal cancers (HR = 0.54, 95% CI 0.36-0.81). Among US veterans, metformin users had lower incidence of diabetes-related cancer, particularly liver, colorectal, and esophageal cancers, as compared to sulfonylurea users. Use of metformin was not associated with non-diabetes-related cancer. Further studies are needed to understand how metformin use impacts cancer incidence in different patient populations.

Metformin inhibits migration and epithelial-to-mesenchymal transition in non-small cell lung cancer cells through AMPK-mediated GDF15 induction

The growth differentiation factor 15 (GDF15) may serve as a biomarker of metformin, which mediates the bodyweight lowering effect of metformin. However, whether GDF15 also serves as a molecular target of metformin to inhibit carcinogenesis remains largely unknown. This study examined the role and molecular mechanisms of GDF15 in the anticancer effects of metformin in non-small cell lung cancer (NSCLC) cells, which has never been reported before. We found that metformin significantly inhibited the migration of NSCLC A549 and NCI-H460 cells and reduced the expression of epithelial-to-mesenchymal transition (EMT)-related molecules, including neuro-cadherin (N-cadherin), matrix metalloproteinase 2 (MMP2), and the zinc finger transcription factor Snail, but increased epithelial cadherin (E-cadherin) expression. Furthermore, metformin increased GDF15 and its upstream transcription factors activated transcription factor 4 (ATF4) and C/EBP-homologous protein (CHOP) expressions and increased AMP-activated protein kinase (AMPK) phosphorylation in NSCLC cells. GDF15 siRNA partially reverses the inhibitory effect of metformin on NSCLC cell migration. Moreover, metformin-induced increases in GDF15, CHOP, and ATF4 expression and the inhibition of migration were partially reversed by treatment with Compound C, a specific AMPK inhibitor. Meanwhile, metformin significantly inhibited NCI-H460 xenograft tumor growth in nude mice, increased GDF15 expression, and regulated EMT- and migration-related protein expression in xenograft tumors. In conclusion, our results provide novel insights into revealing that GDF15 can serve as a potential molecular target of metformin owing to its anti-cancer effect in NSCLC, which is mediated by AMPK activation.

Type 2 diabetes incidence in patients initiating denosumab or alendronate treatment: a primary care cohort study

Denosumab initiation is related to a lower risk of type 2 diabetes than alendronate in anti-osteoporotic treatment-naïve users in primary care practices.

PURPOSE

Links have been suggested between bone metabolism and glucose tolerance. Downregulation of the receptor activator of nuclear factor κ B ligand (RANKL) signaling improves glucose metabolism. Denosumab, a human monoclonal antibody against RANKL, may be associated with a lower risk of type 2 diabetes (T2D). The aim was to compare incidence rates of T2DM in primary care patients initiating denosumab or alendronate, which is a first-line therapy of osteoporosis. Alendronate as comparator enhances comparability of the two cohorts.

METHOD

The IQVIA Disease Analyzer comprises a representative panel of general and specialist practices (Germany). A new-user comparative study was conducted among patients with denosumab or alendronate treatment (2010-2021) without history of diabetes and age ≥ 45 years. Incidence rates (per 1,000 person-years) and Cox proportional hazard ratios (HR; 95%CI) for T2DM were estimated.

RESULTS

The cohorts consisted of 3,354 denosumab (age: 75 years; women: 87%) and 27,068 alendronate (76 years; 86%) users. Overall, 1,038 persons developed T2D during 54,916 person-years. T2DM incidence rates per 1,000 person-years were 11.9 (9.5-14.4) for denosumab and 20.1 (18.8-21.3) for alendronate users, respectively. Denosumab was associated with a reduced risk of T2DM compared to alendronate, adjusting for age, sex, index year, visits, obesity, comorbidities and statins (HR: 0.73; 0.58-0.89).

CONCLUSION

In this comparative study of older patients seen in routine practices, denosumab was associated with a lower risk of developing T2DM than alendronate.

Metformin combined with cisplatin reduces anticancer activity via ATM/CHK2-dependent upregulation of Rad51 pathway in ovarian cancer

Ovarian cancer (OC) is the deadliest malignancy of the female reproductive system. The standard first-line therapy for OC involves cytoreductive surgical debulking followed by chemotherapy based on platinum and paclitaxel. Despite these treatments, there remains a high rate of tumor recurrence and resistance to platinum. Recent studies have highlighted the potential anti-tumor properties of metformin (met), a traditional diabetes drug. In our study, we investigated the impact of met on the anticancer activities of cisplatin (cDDP) both in vitro and in vivo. Our findings revealed that combining met with cisplatin significantly reduced apoptosis in OC cells, decreased DNA damage, and induced resistance to cDDP. Furthermore, our mechanistic study indicated that the resistance induced by met is primarily driven by the inhibition of the ATM/CHK2 pathway and the upregulation of the Rad51 protein. Using an ATM inhibitor, KU55933, effectively reversed the cisplatin resistance phenotype. In conclusion, our results suggest that met can antagonize the effects of cDDP in specific types of OC cells, leading to a reduction in the chemotherapeutic efficacy of cDDP.

Too good to be true: Are GLP-1 receptor agonists the new metformin?

Recently, a health-care database study showed that persons with type 2 diabetes taking GLP-1 receptor agonists (GLP-1 RA) had a significantly lower risk of 10 out of 13 obesity-related cancers than patients taking insulin (Wang L, et al. JAMA Netw Open. 2024 7: e2421305). For some cancers, hazard ratios <0.5 were reported. This is reminiscent of studies published >10 years ago showing that people with type 2 diabetes taking metformin had a lower risk of many types of cancer than those not taking metformin. In some studies, also risk reductions of >50 % were reported. The strong effects observed in the metformin studies were explained by time-related biases, in particular, immortal time bias. In the current GLP-1 RA study, it was striking that the curves for the cumulative incidence of several cancers in GLP-1 RA and insulin users diverged immediately after therapy onset. This indicates that there is most likely a time-related bias: insulin is given at much later stages of type 2 diabetes than GLP-1 RA. The current study suggests that one should be sceptical about database results when spectacular risk reductions are reported. Time-related bias should always be considered as an alternative explanation.

Repurposing metabolic regulators: antidiabetic drugs as anticancer agents

Drug repurposing in cancer taps into the capabilities of existing drugs, initially designed for other ailments, as potential cancer treatments. It offers several advantages over traditional drug discovery, including reduced costs, reduced development timelines, and a lower risk of adverse effects. However, not all drug classes align seamlessly with a patient's condition or long-term usage. Hence, repurposing of chronically used drugs presents a more attractive option. On the other hand, metabolic reprogramming being an important hallmark of cancer paves the metabolic regulators as possible cancer therapeutics. This review emphasizes the importance and offers current insights into the repurposing of antidiabetic drugs, including metformin, sulfonylureas, sodium-glucose cotransporter 2 (SGLT2) inhibitors, dipeptidyl peptidase 4 (DPP-4) inhibitors, glucagon-like peptide-1 receptor agonists (GLP-1RAs), thiazolidinediones (TZD), and α-glucosidase inhibitors, against various types of cancers. Antidiabetic drugs, regulating metabolic pathways have gained considerable attention in cancer research. The literature reveals a complex relationship between antidiabetic drugs and cancer risk. Among the antidiabetic drugs, metformin may possess anti-cancer properties, potentially reducing cancer cell proliferation, inducing apoptosis, and enhancing cancer cell sensitivity to chemotherapy. However, other antidiabetic drugs have revealed heterogeneous responses. Sulfonylureas and TZDs have not demonstrated consistent anti-cancer activity, while SGLT2 inhibitors and DPP-4 inhibitors have shown some potential benefits. GLP-1RAs have raised concerns due to possible associations with an increased risk of certain cancers. This review highlights that further research is warranted to elucidate the mechanisms underlying the potential anti-cancer effects of these drugs and to establish their efficacy and safety in clinical settings.

Repurposing Drugs for Cancer Prevention: Targeting Mechanisms Common to Chronic Diseases

ABSTRACT

The development of agents for cancer prevention is a lengthy process requiring a delicate balance between the safety and tolerability of potential interventions and effectiveness in preventing future cancer. Individuals at risk for a specific cancer are frequently at risk for multiple types of cancer as well as other chronic diseases, especially ones associated with aging. Shared environmental exposures, genetic predisposition, metabolic factors, and commonalities in pathogenesis suggest opportunities for combined targeting of cancer and other chronic diseases. Examples discussed here include mechanisms shared between various cancers and obesity, diabetes, and cardiovascular disease.

Current advance of nanotechnology in diagnosis and treatment for malignant tumors

Cancer remains a significant risk to human health. Nanomedicine is a new multidisciplinary field that is garnering a lot of interest and investigation. Nanomedicine shows great potential for cancer diagnosis and treatment. Specifically engineered nanoparticles can be employed as contrast agents in cancer diagnostics to enable high sensitivity and high-resolution tumor detection by imaging examinations. Novel approaches for tumor labeling and detection are also made possible by the use of nanoprobes and nanobiosensors. The achievement of targeted medication delivery in cancer therapy can be accomplished through the rational design and manufacture of nanodrug carriers. Nanoparticles have the capability to effectively transport medications or gene fragments to tumor tissues via passive or active targeting processes, thus enhancing treatment outcomes while minimizing harm to healthy tissues. Simultaneously, nanoparticles can be employed in the context of radiation sensitization and photothermal therapy to enhance the therapeutic efficacy of malignant tumors. This review presents a literature overview and summary of how nanotechnology is used in the diagnosis and treatment of malignant tumors. According to oncological diseases originating from different systems of the body and combining the pathophysiological features of cancers at different sites, we review the most recent developments in nanotechnology applications. Finally, we briefly discuss the prospects and challenges of nanotechnology in cancer.

Metformin in Chemoprevention of Lung Cancer: A Retrospective Population-Based Cohort Study in Lithuania

Background and Objectives: This study aimed to evaluate the potential chemopreventive effect of antidiabetic medications, specifically metformin and pioglitazone, on lung cancer in patients with type 2 diabetes mellitus (T2DM). Additionally, the potential dose-response relationship for metformin use was analyzed. Methods: We conducted a retrospective cohort study utilizing comprehensive national health insurance and cancer registry databases to gather a large cohort of T2DM patients. Cox proportional hazards regression models were used to assess the risk of lung cancer across different antidiabetic medication groups, adjusting for potential confounders such as age and gender. A dose-response analysis was conducted for metformin users. Results: Our results indicated that metformin users had a significantly lower lung cancer risk than the reference group (HR = 0.69, 95% CI [0.55-0.86], p = 0.001). The risk reduction increased with higher cumulative metformin doses: a metformin cumulative dose between 1,370,000 and 2,976,000 had an HR of 0.61 (95% CI [0.49-0.75], p < 0.001) vs. cumulative metformin dose >2,976,000 which had an HR of 0.35 (95% CI [0.21-0.59], p < 0.001). No significant association between pioglitazone use and the risk of lung cancer was found (HR = 1.00, 95% CI [0.25-4.02]). Conclusions: This study shows that metformin may have a dose-dependent chemopreventive effect against lung cancer in T2DM, while the impact of pioglitazone remains unclear and requires further investigation.

The SARIFA biomarker in the context of basic research of lipid-driven cancers

SARIFA was very recently introduced as a histomorphological biomarker with strong prognostic power for colorectal, gastric, prostate, and pancreatic cancer. It is characterized by the direct contact between tumor cells and adipocytes due to a lack of stromal reaction. This can be easily evaluated on routinely available H&E-slides with high interobserver agreement. SARIFA also reflects a specific tumor biology driven by metabolic reprogramming. Tumor cells in SARIFA-positive tumors benefit from direct interaction with adipocytes as an external source of lipids. Numerous studies have shown that lipid metabolism is crucial in carcinogenesis and cancer progression. We found that the interaction between tumor cells and adipocytes was not triggered by obesity, as previously assumed. Instead, we believe that this is due to an immunological mechanism. Knowledge about lipid metabolism in cancer from basic experiments can be transferred to develop strategies targeting this reprogramed metabolism.

N-linked glycosylation of PD-L1/PD-1: an emerging target for cancer diagnosis and treatment

During tumorigenesis and progression, the immune checkpoint programmed death-1 (PD-1) and its ligand programmed death ligand-1 (PD-L1) play critical roles in suppressing T cell-mediated anticancer immune responses, leading to T-cell exhaustion and subsequent tumor evasion. Therefore, anti-PD-L1/PD-1 therapy has been an attractive strategy for treating cancer over the past decade. However, the overall efficacy of this approach remains suboptimal, revealing an urgent need for novel insights. Interestingly, increasing evidence indicates that both PD-L1 on tumor cells and PD-1 on tumor-specific T cells undergo extensive N-linked glycosylation, which is essential for the stability and interaction of these proteins, and this modification promotes tumor evasion. In various preclinical models, targeting the N-linked glycosylation of PD-L1/PD-1 was shown to significantly increase the efficacy of PD-L1/PD-1 blockade therapy. Furthermore, deglycosylation of PD-L1 strengthens the signal intensity in PD-L1 immunohistochemistry (IHC) assays, improving the diagnostic and therapeutic relevance of this protein. In this review, we provide an overview of the regulatory mechanisms underlying the N-linked glycosylation of PD-L1/PD-1 as well as the crucial role of N-linked glycosylation in PD-L1/PD-1-mediated immune evasion. In addition, we highlight the promising implications of targeting the N-linked glycosylation of PD-L1/PD-1 in the clinical diagnosis and treatment of cancer. Our review identifies knowledge gaps and sheds new light on the cancer research field.

Targeting cancer and immune cell metabolism with the complex I inhibitors metformin and IACS-010759

Metformin and IACS-010759 are two distinct antimetabolic agents. Metformin, an established antidiabetic drug, mildly inhibits mitochondrial complex I, while IACS-010759 is a new potent mitochondrial complex I inhibitor. Mitochondria is pivotal in the energy metabolism of cells by providing adenosine triphosphate through oxidative phosphorylation (OXPHOS). Hence, mitochondrial metabolism and OXPHOS become a vulnerability when targeted in cancer cells. Both drugs have promising antitumoral effects in diverse cancers, supported by preclinical in vitro and in vivo studies. We present evidence of their direct impact on cancer cells and their immunomodulatory effects. In clinical studies, while observational epidemiologic studies on metformin were encouraging, actual trial results were not as expected. However, IACS-01075 exhibited major adverse effects, thereby causing a metabolic shift to glycolysis and elevated lactic acid concentrations. Therefore, the future outlook for these two drugs depends on preventive clinical trials for metformin and investigations into the plausible toxic effects on normal cells for IACS-01075.

Repurposing Metformin for the Treatment of Atrial Fibrillation: Current Insights

Metformin is an orally effective anti-hyperglycemic drug that despite being introduced over 60 years ago is still utilized by an estimated 120 to 150 million people worldwide for the treatment of type 2 diabetes (T2D). Metformin is used off-label for the treatment of polycystic ovary syndrome (PCOS) and for pre-diabetes and weight loss. Metformin is a safe, inexpensive drug with side effects mostly limited to gastrointestinal issues. Prospective clinical data from the United Kingdom Prospective Diabetes Study (UKPDS), completed in 1998, demonstrated that metformin not only has excellent therapeutic efficacy as an anti-diabetes drug but also that good glycemic control reduced the risk of micro- and macro-vascular complications, especially in obese patients and thereby reduced the risk of diabetes-associated cardiovascular disease (CVD). Based on a long history of clinical use and an excellent safety record metformin has been investigated to be repurposed for numerous other diseases including as an anti-aging agent, Alzheimer's disease and other dementias, cancer, COVID-19 and also atrial fibrillation (AF). AF is the most frequently diagnosed cardiac arrythmia and its prevalence is increasing globally as the population ages. The argument for repurposing metformin for AF is based on a combination of retrospective clinical data and in vivo and in vitro pre-clinical laboratory studies. In this review, we critically evaluate the evidence that metformin has cardioprotective actions and assess whether the clinical and pre-clinical evidence support the use of metformin to reduce the risk and treat AF.

Tumor initiation and early tumorigenesis: molecular mechanisms and interventional targets

Tumorigenesis is a multistep process, with oncogenic mutations in a normal cell conferring clonal advantage as the initial event. However, despite pervasive somatic mutations and clonal expansion in normal tissues, their transformation into cancer remains a rare event, indicating the presence of additional driver events for progression to an irreversible, highly heterogeneous, and invasive lesion. Recently, researchers are emphasizing the mechanisms of environmental tumor risk factors and epigenetic alterations that are profoundly influencing early clonal expansion and malignant evolution, independently of inducing mutations. Additionally, clonal evolution in tumorigenesis reflects a multifaceted interplay between cell-intrinsic identities and various cell-extrinsic factors that exert selective pressures to either restrain uncontrolled proliferation or allow specific clones to progress into tumors. However, the mechanisms by which driver events induce both intrinsic cellular competency and remodel environmental stress to facilitate malignant transformation are not fully understood. In this review, we summarize the genetic, epigenetic, and external driver events, and their effects on the co-evolution of the transformed cells and their ecosystem during tumor initiation and early malignant evolution. A deeper understanding of the earliest molecular events holds promise for translational applications, predicting individuals at high-risk of tumor and developing strategies to intercept malignant transformation.

Clinical evidence for the prognostic impact of metformin in cancer patients treated with immune checkpoint inhibitors

BACKGROUND

Preclinical studies suggest that metformin might enhance the efficacy of immune checkpoint inhibitors (ICIs) and potentially influence the prognoses of cancer patients undergoing ICIs treatment. This study endeavors to assess the prognostic significance of metformin in cancer patients undergoing ICIs therapy, aiming to furnish evidence-based insights for clinical practice.

METHODS

A thorough literature search was conducted across electronic databases to encompass all potential records published before November 20th, 2023. A meta-analysis was executed utilizing Stata 17.0 to derive pooled hazard ratios (HRs) with 95% confidence intervals (CIs) for both overall survival (OS) and progression-free survival (PFS).

RESULTS

A total of 22 studies encompassing 9,011 patients met the inclusion criteria. Meta-analyses revealed a significant correlation between metformin use and poorer OS (HR, 1.13; 95 %CI, 1.04-1.23; P = 0.004) rather than PFS (HR, 1.04; 95 %CI, 0.96-1.14; P = 0.345) among cancer patients undergoing ICIs treatment. Subgroup analysis delineated that the concurrent administration of metformin and ICIs significantly associated with adverse prognoses in the European population (OS: HR, 1.23; 95 %CI, 1.10-1.39; P = 0.001; PFS: HR, 1.14; 95 %CI, 1.02-1.28; P = 0.024).

CONCLUSION

Based on current clinical evidence, concomitant metformin use does not appear to improve the prognostic outcomes for cancer patients undergoing ICIs therapy and may potentially correlate with inferior prognoses. Further studies are imperative to comprehensively elucidate the impact of metformin within the realm of ICIs therapy.

New evidence: Metformin unsuitable as routine adjuvant for breast cancer: a drug-target mendelian randomization analysis

PURPOSE

The potential efficacy of metformin in breast cancer (BC) has been hotly discussed but never conclusive. This genetics-based study aimed to evaluate the relationships between metformin targets and BC risk.

METHODS

Metformin targets from DrugBank and genome-wide association study (GWAS) data from IEU OpenGWAS and FinnGen were used to investigate the breast cancer (BC)-metformin causal link with various Mendelian Randomization (MR) methods (e.g., inverse-variance-weighting). The genetic association between type 2 diabetes (T2D) and the drug target of metformin was also analyzed as a positive control. Sensitivity and pleiotropic tests ensured reliability.

RESULTS

The primary targets of metformin are PRKAB1, ETFDH and GPD1L. We found a causal association between PRKAB1 and T2D (odds ratio [OR] 0.959, P = 0.002), but no causal relationship was observed between metformin targets and overall BC risk (PRKAB1: OR 0.990, P = 0.530; ETFDH: OR 0.986, P = 0.592; GPD1L: OR 1.002, P = 0.806). A noteworthy causal relationship was observed between ETFDH and estrogen receptor (ER)-positive BC (OR 0.867, P = 0.018), and between GPD1L and human epidermal growth factor receptor 2 (HER2)-negative BC (OR 0.966, P = 0.040). Other group analyses did not yield positive results.

CONCLUSION

The star target of metformin, PRKAB1, does not exhibit a substantial causal association with the risk of BC. Conversely, metformin, acting as an inhibitor of ETFDH and GPD1L, may potentially elevate the likelihood of developing ER-positive BC and HER2-negative BC. Consequently, it is not advisable to employ metformin as a standard supplementary therapy for BC patients without T2D.

Metformin: From Diabetes to Cancer-Unveiling Molecular Mechanisms and Therapeutic Strategies

Metformin, a widely used anti-diabetic drug, has garnered attention for its potential in cancer management, particularly in breast and colorectal cancer. It is established that metformin reduces mitochondrial respiration, but its specific molecular targets within mitochondria vary. Proposed mechanisms include inhibiting mitochondrial respiratory chain Complex I and/or Complex IV, and mitochondrial glycerophosphate dehydrogenase, among others. These actions lead to cellular energy deficits, redox state changes, and several molecular changes that reduce hyperglycemia in type 2 diabetic patients. Clinical evidence supports metformin's role in cancer prevention in type 2 diabetes mellitus patients. Moreover, in these patients with breast and colorectal cancer, metformin consumption leads to an improvement in survival outcomes and prognosis. The synergistic effects of metformin with chemotherapy and immunotherapy highlights its potential as an adjunctive therapy for breast and colorectal cancer. However, nuanced findings underscore the need for further research and stratification by molecular subtype, particularly for breast cancer. This comprehensive review integrates metformin-related findings from epidemiological, clinical, and preclinical studies in breast and colorectal cancer. Here, we discuss current research addressed to define metformin's bioavailability and efficacy, exploring novel metformin-based compounds and drug delivery systems, including derivatives targeting mitochondria, combination therapies, and novel nanoformulations, showing enhanced anticancer effects.

The Past and Future of Inflammation as a Target to Cancer Prevention

Inflammation is an essential defense mechanism in which innate immune cells are coordinately activated on encounter of harmful stimuli, including pathogens, tissue injury, and toxic compounds and metabolites to neutralize and eliminate the instigator and initiate healing and regeneration. Properly terminated inflammation is vital to health, but uncontrolled runaway inflammation that becomes chronic begets a variety of inflammatory and metabolic diseases and increases cancer risk. Making damaged tissues behave as "wounds that do not heal" and sustaining the production of growth factors whose physiologic function is tissue healing, chronic inflammation accelerates cancer emergence from premalignant lesions. In 1863, Rudolf Virchow, a leading German pathologist, suggested a possible association between inflammation and tumor formation, but it took another 140 years to fully elucidate and appreciate the tumorigenic role of inflammation. Key findings outlined molecular events in the inflammatory cascade that promote cancer onset and progression and enabled a better appreciation of when and where inflammation should be inhibited. These efforts triggered ongoing research work to discover and develop inflammation-reducing chemopreventive strategies for decreasing cancer risk and incidence.

Ianus Bifrons: The Two Faces of Metformin

The ancient Roman god Ianus was a mysterious divinity with two opposite faces, one looking at the past and the other looking to the future. Likewise, metformin is an "old" drug, with one side looking at the metabolic role and the other looking at the anti-proliferative mechanism; therefore, it represents a typical and ideal bridge between diabetes and cancer. Metformin (1,1-dimethylbiguanidine hydrochloride) is a drug that has long been in use for the treatment of type 2 diabetes mellitus, but recently evidence is growing about its potential use in other metabolic conditions and in proliferative-associated diseases. The aim of this paper is to retrace, from a historical perspective, the knowledge of this molecule, shedding light on the subcellular mechanisms of action involved in metabolism as well as cellular and tissue growth. The intra-tumoral pharmacodynamic effects of metformin and its possible role in the management of different neoplasms are evaluated and debated. The etymology of the name Ianus is probably from the Latin term ianua, which means door. How many new doors will this old drug be able to open?

Metformin and Breast Cancer: Current Findings and Future Perspectives from Preclinical and Clinical Studies

Over the last several decades, a growing body of research has investigated the potential to repurpose the anti-diabetic drug metformin for breast cancer prevention and/or treatment. Observational studies in the early 2000s demonstrated that patients with diabetes taking metformin had decreased cancer risk, providing the first evidence supporting the potential role of metformin as an anti-cancer agent. Despite substantial efforts, two decades later, the exact mechanisms and clinical efficacy of metformin for breast cancer remain ambiguous. Here, we have summarized key findings from studies examining the effect of metformin on breast cancer across the translational spectrum including in vitro, in vivo, and human studies. Importantly, we discuss critical factors that may help explain the significant heterogeneity in study outcomes, highlighting how metformin dose, underlying metabolic health, menopausal status, tumor subtype, membrane transporter expression, diet, and other factors may play a role in modulating metformin's anti-cancer effects. We hope that these insights will help with interpreting data from completed studies, improve the design of future studies, and aid in the identification of patient subsets with breast cancer or at high risk for the disease who are most likely to benefit from metformin treatment.

Advances in macrophage and T cell metabolic reprogramming and immunotherapy in the tumor microenvironment

Macrophages and T cells in the tumor microenvironment (TME) play an important role in tumorigenesis and progression. However, TME is also characterized by metabolic reprogramming, which may affect macrophage and metabolic activity of T cells and promote tumor escape. Immunotherapy is an approach to fight tumors by stimulating the immune system in the host, but requires support and modulation of cellular metabolism. In this process, the metabolic roles of macrophages and T cells become increasingly important, and their metabolic status and interactions play a critical role in the success of immunotherapy. Therefore, understanding the metabolic state of T cells and macrophages in the TME and the impact of metabolic reprogramming on tumor therapy will help optimize subsequent immunotherapy strategies.

Repurposing Therapeutic Drugs Complexed to Vanadium in Cancer

Repurposing drugs by uncovering new indications for approved drugs accelerates the process of establishing new treatments and reduces the high costs of drug discovery and development. Metal complexes with clinically approved drugs allow further opportunities in cancer therapy-many vanadium compounds have previously shown antitumor effects, which makes vanadium a suitable metal to complex with therapeutic drugs, potentially improving their efficacy in cancer treatment. In this review, covering the last 25 years of research in the field, we identified non-oncology-approved drugs suitable as ligands to obtain different vanadium complexes. Metformin-decavanadate, vanadium-bisphosphonates, vanadyl(IV) complexes with non-steroidal anti-inflammatory drugs, and cetirizine and imidazole-based oxidovanadium(IV) complexes, each has a parent drug known to have different medicinal properties and therapeutic indications, and all showed potential as novel anticancer treatments. Nevertheless, the precise mechanisms of action for these vanadium compounds against cancer are still not fully understood.

Anti-Proliferative Properties of the Novel Hybrid Drug Met-ITC, Composed of the Native Drug Metformin with the Addition of an Isothiocyanate H2S Donor Moiety, in Different Cancer Cell Lines

Metformin (Met) is the first-line therapy in type 2 diabetes mellitus but, in last few years, it has also been evaluated as anti-cancer agent. Several pathways, such as AMPK or PI3K/Akt/mTOR, are likely to be involved in the anti-cancer Met activity. In addition, hydrogen sulfide (H2S) and H2S donors have been described as anti-cancer agents affecting cell-cycle and inducing apoptosis. Among H2S donors, isothiocyanates are endowed with a further anti-cancer mechanism: the inhibition of the histone deacetylase enzymes. On this basis, a hybrid molecule (Met-ITC) obtained through the addition of an isothiocyanate moiety to the Met molecule was designed and its ability to release Met has been demonstrated. Met-ITC exhibited more efficacy and potency than Met in inhibiting cancer cells (AsPC-1, MIA PaCa-2, MCF-7) viability and it was less effective on non-tumorigenic cells (MCF 10-A). The ability of Met-ITC to release H2S has been recorded both in cell-free and in cancer cells assays. Finally, its ability to affect the cell cycle and to induce both early and late apoptosis has been demonstrated on the most sensitive cell line (MCF-7). These results confirmed that Met-ITC is a new hybrid molecule endowed with potential anti-cancer properties derived both from Met and H2S.