Metformin and prostate cancer: reduced development of castration-resistant disease and prostate cancer mortality

Effect of BMI and hemoglobin A1c on survival of veterans with metastatic castration-resistant prostate cancer treated with abiraterone or enzalutamide

BACKGROUND

Abiraterone acetate and enzalutamide are two common therapies for metastatic castration-resistant prostate cancer (mCRPC) that have shown improved overall survival (OS). The drugs have different mechanisms of action with limited comparative trials to evaluate treatment in patients with comorbidities such as obesity and diabetes. This is important since abiraterone requires the co-administration of prednisone. We assessed the relationship between body mass index (BMI), hemoglobin A1c (HbA1c), treatment, and survival in mCRPC.

METHODS

Veterans treated with abiraterone or enzalutamide within the Veterans Health Administration between September 10, 2014 and June 2, 2017 with BMI and HbA1c were identified. Additional variables included age, baseline prostate-specific antigen at first treatment for mCRPC, race, and the Charlson comorbidity index. Differences in survival were compared using the Kaplan-Meier method. Cox proportional hazards regression modeling was used to assess the association between initial treatment, BMI, and HbA1c while adjusting for confounding variables.

RESULTS

A total of 5231 patients were identified with a mean age of 75.2 years and 1241 (23.7%) were of black race. BMI was associated with OS with longest median survival of 29.8 months in BMI ≥ 30 (n = 1903), 23.9 months in BMI 25-30 (n = 1879), 15.9 months in BMI 18.5-25 (n = 1336), and 9.2 months in BMI < 18.5 (n = 113, p < 0.001). In a multivariable model compared to normal BMI, increased mortality was observed in BMI < 18.5 (adjusted hazard ratio (aHR) = 1.583, 95% confidence interval [CI]: 1.29-1.94) and a decreased mortality in BMI 25-30 (aHR = 0.751, 95% CI: 0.69-0.81) and BMI > 30 (aHR = 0.644, 95% CI: 0.59-0.70). In 3761 patients with BMI > 25, there was longer OS in patients treated with enzalutamide (28.4 months, n = 1615) compared to abiraterone (25.8 months, n = 2146, p = 0.002). In 1470 patients with BMI < 25, there was no difference in OS between patients treated with enzalutamide (16.0 months, n = 597, p = 0.513) or abiraterone (16.1 months, n = 873). In 1333 veterans with HbA1c ≥ 6.5%, initial prescription of enzalutamide was associated with longer OS compared with abiraterone (24.4 vs. 20.5 months, p = 0.0005). In 2088 patients with HbA1c < 6.5%, there was no difference in OS in patients who were initially prescribed enzalutamide versus abiraterone (25.7 vs. 23.5 months, p = 0.334).

CONCLUSIONS

In veterans with mCRPC, increased BMI was associated with longer survival. Veterans with BMI > 25 had longer survival with enzalutamide compared to abiraterone. In patients with HbA1c ≥ 6.5%, enzalutamide was associated with longer survival compared to abiraterone. These results may facilitate prognostication of survival and improve treatment selection based on patient comorbidities.

Post-diagnostic metformin and statin use and risk of biochemical recurrence in Veterans diagnosed with prostate cancer

OBJECTIVE

To evaluate the impact of post-diagnostic metformin or statin use and duration on risk of biochemical recurrence in a racially-diverse cohort of Veterans.

METHODS

The population consisted of men diagnosed with prostate cancer in the Veterans Health Administration and treated with either radical prostatectomy or radiation (Full cohort n = 65,759, Black men n = 18,817, White men n = 46,631, Other = 311). The association between post-diagnostic (1) metformin and (2) statin use with biochemical recurrence was assessed using multivariable, time-varying Cox Proportional Hazard Models for the overall cohort and by race. In a secondary analysis, metformin and statin duration were evaluated.

RESULTS

Post-diagnostic metformin use was not associated with biochemical recurrence (multivariable-adjusted hazard ratio [aHR]: 1.01; 95% confidence interval [CI]: 0.94, 1.09), with similar results observed for both Black and White men. However, duration of metformin use was associated with a reduced risk of biochemical recurrence in the cohort overall (HR: 0.94; 95% CI: 0.92, 0.95) as well as both Black and White men. By contrast, statin use was associated with a reduced risk of biochemical recurrence (HR: 0.83; 95% CI: 0.79, 0.88) in the overall cohort as well as both White and Black men. Duration of statin use was also inversely associated with biochemical recurrence in all groups.

CONCLUSION

Post-diagnostic metformin and statin use have the potential to prevent biochemical recurrence in men diagnosed with prostate cancer.

Metformin escape in prostate cancer by activating the PTGR1 transcriptional program through a novel super-enhancer

The therapeutic efficacy of metformin in prostate cancer (PCa) appears uncertain based on various clinical trials. Metformin treatment failure may be attributed to the high frequency of transcriptional dysregulation, which leads to drug resistance. However, the underlying mechanism is still unclear. In this study, we found evidences that metformin resistance in PCa cells may be linked to cell cycle reactivation. Super-enhancers (SEs), crucial regulatory elements, have been shown to be associated with drug resistance in various cancers. Our analysis of SEs in metformin-resistant (MetR) PCa cells revealed a correlation with Prostaglandin Reductase 1 (PTGR1) expression, which was identified as significantly increased in a cluster of cells with metformin resistance through single-cell transcriptome sequencing. Our functional experiments showed that PTGR1 overexpression accelerated cell cycle progression by promoting progression from the G0/G1 to the S and G2/M phases, resulting in reduced sensitivity to metformin. Additionally, we identified key transcription factors that significantly increase PTGR1 expression, such as SRF and RUNX3, providing potential new targets to address metformin resistance in PCa. In conclusion, our study sheds new light on the cellular mechanism underlying metformin resistance and the regulation of the SE-TFs-PTGR1 axis, offering potential avenues to enhance metformin's therapeutic efficacy in PCa.

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

The quest to repurpose metformin, an antidiabetes drug, as an agent for cancer prevention and treatment, which began in 2005 with an observational study that reported a reduction in cancer incidence among metformin users, generated extensive experimental, observational, and clinical research. Experimental studies revealed that metformin has anticancer effects via various pathways, potentially inhibiting cancer cell proliferation. Concurrently, multiple nonrandomized observational studies reported remarkable reductions in cancer incidence and outcomes with metformin use. However, these studies were shown, in 2012, to be affected by time-related biases, such as immortal time bias, which tend to greatly exaggerate the benefit of a drug. The observational studies that avoided these biases did not find an association. Subsequently, the randomized trials of metformin for the treatment of type 2 diabetes and as adjuvant therapy for the treatment of various cancers, advanced or metastatic, did not find reductions in cancer incidence or outcomes. Most recently, the largest phase 3 randomized trial of metformin as adjuvant therapy for breast cancer, which enrolled 3,649 women with a 5-year follow-up, found no benefit for disease-free survival or overall survival with metformin. This major failure of observational real-world evidence studies in correctly assessing the effects of metformin on cancer incidence and outcomes was caused by preventable biases which, surprisingly, are still prominent in 2022. Rigorous approaches for observational studies that emulate randomized trials, such as the incident and prevalent new-user designs along with propensity scores, avoid these biases and can provide more accurate real-world evidence for the repurposing of drugs such as metformin.

Repression of SLC22A3 by the AR-V7/YAP1/TAZ axis in enzalutamide-resistant castration-resistant prostate cancer

Metastatic castration-resistant prostate cancer (mCRPC) is an aggressive and fatal disease, with most patients succumbing within 1-2 years despite undergoing multiple treatments. Androgen-receptor (AR) inhibitors, including enzalutamide (ENZ), are used for the treatment of mCRPC; however, most patients develop resistance to ENZ. Herein, we propose that the repression of SLC22A3 by AR-V7/YAP1/TAZ conferred ENZ resistance in mCRPC. SLC22A3 expression is specifically downregulated in the ENZ-resistant C4-2B MDVR cells, and when YAP1/TAZ is hyperactivated by AR full-length or AR-V7, these proteins interact with DNMT1 to repress SLC22A3 expression. We observed low SLC22A3 expression and high levels of TAZ or YAP1 in mCRPC patient tissues harbouring AR-V7 and the opposite expression patterns in normal patient tissues. Our findings suggest a mechanism underlying ENZ resistance by providing evidence that the AR-V7/YAP1/TAZ axis represses SLC22A3, which could be a potential treatment target in prostate cancer.

A Retrospective Study of the Effect of Metformin on Patients with Metastatic Prostate Cancer

Introduction

Previous studies demonstrated that metformin could lead to an inhibition of proliferation of cancer cells through a shift from anabolic to catabolic metabolism. In this study, we seek to investigate the effect of metformin in metastatic prostate cancer.

Methods

Patients followed at Northwell Health Zuckerberg Cancer Center during 2014-2018 were included if they were diagnosed with metastatic hormone-sensitive prostate cancer (mHSPC) or metastatic castration-resistant prostate cancer (mCRPC), with ⩾6 months follow-up with and without metformin treatment. The primary outcomes, 6-month prostate-specific antigen (PSA) response, overall survival (OS), and radiographic progression free survival (rPFS), were evaluated.

Results

There were 267 patients included in the final analysis; 196 patients had mHSPC (73.2%) and 71 had mCRPC (26.8%). Within the mHSPC subjects, there was a significant difference in OS between metformin vs nonmetformin groups (148.5 vs 85.6 months; P < .046) in a univariate analysis; patients who took metformin had a significantly longer OS than subjects who did not (median OS: 148.5 vs 86 months; P < .046). There was no significant difference between the 2 groups with respect to either PSA response rate at 6 months or rPFS or OS in patients with mHSPC in both univariate and multivariate analysis. Within the mCRPC subjects, there was no significant difference between metformin and nonmetformin groups with respect to OS (43.3 vs 51.5 months; P < 0.160) or PSA response at 6 months (38.5% vs 57.1%; p < 0.24); however, patients on metformin had a significantly shorter rPFS in both the univariate analysis (7.3 vs 17.4; P < .0002) and in the multivariate analysis (HR = 2.52; 95% CI: 1.24m 5.11; P < .0109).

Conclusions

Among patients with mHSPC, use of metformin was not significantly associated with improved OS in the multivariate analysis.

Metformin for Prevention of Anthropometric and Metabolic Complications of Androgen Deprivation Therapy in Prostate Cancer Patients Receiving Radical Radiotherapy: A Phase II Randomized Controlled Trial

BACKGROUND

Patients with prostate cancer undergoing treatment with radical radiation therapy (RT) plus androgen deprivation therapy (ADT) experience a constellation of deleterious metabolic and anthropometric changes related to hypogonadism that are associated with increased morbidity and mortality. We assessed the effect of metformin versus placebo to blunt the adverse effects of ADT on body weight, waist circumference, and other metabolic parameters.

METHODS AND MATERIALS

This phase 2, multicenter, randomized controlled trial (RCT) randomized normoglycemic men with locally advanced prostate cancer receiving radical RT and ADT (18-36 months) in a 1:1 ratio to receive metformin 500 mg by mouth 3 times a day (for 30-36 months) versus identical placebo.

RESULTS

From December 2015 to October 2019, 83 men were randomized with median follow-up of 23 months. Baseline mean body mass Index (BMI) of the cohort was 30.2 (range 22.2-52.5). Change in mean weight relative to baseline was lower among men who received metformin compared with placebo at 5 months (-1.80 kg, P = .038), but was not significant with longer follow-up (1 year: +0.16 kg, P = .874). Although participants on ADT had increases in waist circumference in both study arms, metformin did not significantly reduce these changes (1 year: +2.79 cm (placebo) versus +1.46 cm (metformin), P = .336). Low-density lipoprotein (LDL) cholesterol was lower in the metformin arm (-0.32 mmol/L) compared with the placebo arm (-0.03 mmol/L) at 5 months (P = .022), but these differences were not significant with longer follow-up (1 year: -0.17 mmol/L vs -0.19 mmol/L, P = .896). There were no differences in HbA1C, triglyceride, high-density lipoprotein (HDL) cholesterol, and total cholesterol by study arm.

CONCLUSIONS

Men receiving radical RT and ADT gained weight and had increases in waist circumference over time that metformin did not significantly mitigate. Although this study did not observe any preventive effect of metformin on the anthropometric and metabolic complications of ADT, metformin continues to be studied in phase 3 RCTs in this patient population to assess its potential antineoplastic effects.

Targeting lipid metabolism in metastatic prostate cancer

Despite key advances in the treatment of prostate cancer (PCa), a proportion of men have de novo resistance, and all will develop resistance to current therapeutics over time. Aberrant lipid metabolism has long been associated with prostate carcinogenesis and progression, but more recently there has been an explosion of preclinical and clinical data which is informing new clinical trials. This review explores the epidemiological links between obesity and metabolic syndrome and PCa, the evidence for altered circulating lipids in PCa and their potential role as biomarkers, as well as novel therapeutic strategies for targeting lipids in men with PCa, including therapies widely used in cardiovascular disease such as statins, metformin and lifestyle modification, as well as novel targeted agents such as sphingosine kinase inhibitors, DES1 inhibitors and agents targeting FASN and beta oxidation.

Metformin use and mortality in Asian, diabetic patients with prostate cancer on androgen deprivation therapy: A population-based study

BACKGROUND

This study aims to examine the associations between metformin use concurrent with androgen deprivation therapy (ADT) and mortality risks in Asian, diabetic patients with prostate cancer (PCa).

METHODS

This study identified diabetic adults with PCa receiving any ADT attending public hospitals in Hong Kong between December 1999 and March 2021 retrospectively, with follow-up until September 2021. Patients with <6 months of medical castration without subsequent bilateral orchidectomy, <6 months of concurrent metformin use and ADT, or missing baseline HbA1c were excluded. Metformin users had ≥180 days of concurrent metformin use and ADT, while non-users had no concurrent metformin use and ADT or never used metformin. The primary outcome was PCa-related mortality. The secondary outcome was all-cause mortality. The study used inverse probability treatment weighting to balance covariates.

RESULTS

The analyzed cohort consisted of 1971 patients (1284 metformin users and 687 non-users; mean age 76.2 ± 7.8 years). Over a mean follow-up of 4.1 ± 3.2 years, metformin users had significantly lower risks of PCa-related mortality (weighted hazard ratio [wHR]: 0.49 [95% confidence interval, CI:  0.39-0.61], p < 0.001) and all-cause mortality (wHR 0.53 [0.46-0.61], p < 0.001), independent of diabetic control or status of chronic kidney disease. Such effects appeared stronger in patients with less advanced PCa, which is reflected by the absence of androgen receptor antagonist or chemotherapy use (p value for interaction: 0.017 for PCa-related mortality; 0.048 for all-cause mortality).

CONCLUSIONS

Metformin use concurrent with ADT was associated with lower risks of mortality in Asian, diabetic patients with PCa.

Systematic review of antitumour efficacy and mechanism of metformin activity in prostate cancer models

Metformin, the first line pharmacotherapy for type 2 diabetes has demonstrated favourable effects in prostate cancer (PCa) across a range of studies evaluating PCa patient outcomes amongst metformin users. However, a lack of rigorously conducted prospective studies has stalled clinical use in this setting. Despite multiple studies evaluating the mechanisms underpinning antitumour effects of metformin in PCa, to date, no reviews have compared these findings. This systematic review and meta-analysis consolidates the mechanisms accounting for the antitumour effect of metformin in PCa and evaluates the antitumour efficacy of metformin in preclinical PCa studies. Data were obtained through Medline and EMBASE, extracted by two independent assessors. Risk of bias was assessed using the TOXR tool. Meta-analysis compared in vivo reductions of PCa tumour volume with metformin. In total, 447 articles were identified with 80 duplicates, and 261 articles excluded based on eligibility criteria. The remaining 106 articles were assessed and 71 excluded, with 35 articles included for systematic review, and eight included for meta-analysis. The mechanisms of action of metformin regarding tumour growth, viability, migration, invasion, cell metabolism, and activation of signalling cascades are individually discussed. The mechanisms by which metformin inhibits PCa cell growth are multimodal. Metformin regulates expression of multiple proteins/genes to inhibit cellular proliferation, cell cycle progression, and cellular invasion and migration. Published in vivo studies also conclusively demonstrate that metformin inhibits PCa growth. This highlights the potential of metformin to be repurposed as an anticancer agent, warranting further investigation of metformin in the setting of PCa.

Metformin regulates multiple signaling pathways within castration-resistant human prostate cancer cells

Background

The biguanide metformin has been shown to not only reduce circulating glucose levels but also suppress in vitro and in vivo growth of prostate cancer. However, the mechanisms underlying the anti-tumor effects of metformin in advanced prostate cancers are not fully understood. The goal of the present study was to define the signaling pathways regulated by metformin in androgen-receptor (AR) positive, castration-resistant prostate cancers.

Methods

Our group used RNA sequencing (RNA-seq) to examine genes regulated by metformin within the C4–2 human prostate cancer cell line. Western blot analysis and quantitative RT-PCR were used to confirm alterations in gene expression and further explore regulation of protein expression by metformin.

Results

Data from the RNA-seq analysis revealed that metformin alters the expression of genes products involved in metabolic pathways, the spliceosome, RNA transport, and protein processing within the endoplasmic reticulum. Gene products involved in ErbB, insulin, mTOR, TGF-β, MAPK, and Wnt signaling pathways are also regulated by metformin. A subset of metformin-regulated gene products were genes known to be direct transcriptional targets of p53 or AR. Western blot analyses and quantitative RT-PCR indicated these alterations in gene expression are due in part to metformin-induced reductions in AR mRNA and protein levels.

Conclusions

Together, our results suggest metformin regulates multiple pathways linked to tumor growth and progression within advanced prostate cancer cells.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-022-10115-3.

Unraveling Mitochondrial Determinants of Tumor Response to Radiation Therapy

Radiotherapy represents a highly targeted and efficient treatment choice in many cancer types, both with curative and palliative intents. Nevertheless, radioresistance, consisting in the adaptive response of the tumor to radiation-induced damage, represents a major clinical problem. A growing body of the literature suggests that mechanisms related to mitochondrial changes and metabolic remodeling might play a major role in radioresistance development. In this work, the main contributors to the acquired cellular radioresistance and their relation with mitochondrial changes in terms of reactive oxygen species, hypoxia, and epigenetic alterations have been discussed. We focused on recent findings pointing to a major role of mitochondria in response to radiotherapy, along with their implication in the mechanisms underlying radioresistance and radiosensitivity, and briefly summarized some of the recently proposed mitochondria-targeting strategies to overcome the radioresistant phenotype in cancer.

Interactions of radiation therapy with common and innovative systemic treatments: Antidiabetic treatments, antihypertensives, lipid-lowering medications, immunosuppressive medications and other radiosensitizing methods

The invention and approval of innovative anticancer therapies in the last decade have revolutionized oncology treatment. Radiotherapy is one of the three traditional pillars in oncology treatment with surgery and systemic therapies. Some standard-of-care combinations of chemoradiotherapy widened the therapeutic window of radiation, while some other chemotherapies such as gemcitabine caused unacceptable toxicities when combined with radiation in lung cancers. Fast-paced progress are specially focused on immunotherapies, targeted-therapies, anti-angiogenic treatment, DNA repair inhibitors, hormonotherapy and cell cycle inhibitors. New anticancer therapeutic arsenals provided new possibilities of combined oncological treatments. The interactions of the radiotherapy with other systemic treatments, such as non-anticancer immunomodulatory/immunosuppressive medications are sometimes overlooked even though they could offer a real therapeutic benefit. In this review, we summarize the new opportunities and the risks of historical and novel combined therapies with radiation: non-anticancer immunomodulatory/immunosuppressive drugs, systemic reoxygenation, new therapies such as nanoparticles and SMAC mimetics. Key biological mechanisms, pre-clinical and available clinical data will be provided to demonstrate the promising opportunities in the years to come.

Characterization of the SGLT2 Interaction Network and Its Regulation by SGLT2 Inhibitors: A Bioinformatic Analysis

Background: Sodium–glucose cotransporter 2 (SGLT2), also known as solute carrier family 5 member 2 (SLC5A2), is a promising target for a new class of drugs primarily established as kidney-targeting, effective glucose-lowering agents used in diabetes mellitus (DM) patients. Increasing evidence indicates that besides renal effects, SGLT2 inhibitors (SGLT2i) have also a systemic impact via indirectly targeting the heart and other tissues. Our hypothesis states that the pleiotropic effects of SGLT2i are associated with their binding force, location of targets in the SGLT2 networks, targets involvement in signaling pathways, and their tissue-specific expression.

Methods: Thus, to investigate differences in SGLT2i impact on human organisms, we re-created the SGLT2 interaction network incorporating its inhibitors and metformin and analyzed its tissue-specific expression using publicly available datasets. We analyzed it in the context of the so-called key terms ( autophagy, oxidative stress, aging, senescence, inflammation, AMPK pathways, and mTOR pathways) which seem to be crucial to elucidating the SGLT2 role in a variety of clinical manifestations.

Results: Analysis of SGLT2 and its network components’ expression confidence identified selected organs in the following order: kidney, liver, adipose tissue, blood, heart, muscle, intestine, brain, and artery according to the TISSUES database. Drug repurposing analysis of known SGLT2i pointed out the influence of SGLT1 regulators on the heart and intestine tissue. Additionally, dapagliflozin seems to also have a stronger impact on brain tissue through the regulation of SGLT3 and SLC5A11. The shortest path analysis identified interaction SIRT1-SGLT2 among the top five interactions across six from seven analyzed networks associated with the key terms. Other top first-level SGLT2 interactors associated with key terms were not only ADIPOQ, INS, GLUT4, ACE, and GLUT1 but also less recognized ILK and ADCY7. Among other interactors which appeared in multiple shortest-path analyses were GPT, COG2, and MGAM. Enrichment analysis of SGLT2 network components showed the highest overrepresentation of hypertensive disease, DM-related diseases for both levels of SGLT2 interactors. Additionally, for the extended SGLT2 network, we observed enrichment in obesity (including SGLT1), cancer-related terms, neuroactive ligand–receptor interaction, and neutrophil-mediated immunity.

Conclusion: This study provides comprehensive and ranked information about the SGLT2 interaction network in the context of tissue expression and can help to predict the clinical effects of the SGLT2i.

Statin and metformin use and outcomes in patients with castration-resistant prostate cancer treated with enzalutamide: A meta-analysis of AFFIRM, PREVAIL and PROSPER

BACKGROUND

Statins and metformin are commonly prescribed for patients, including those with prostate cancer. Preclinical and epidemiologic studies of each agent have suggested anti-cancer properties.

METHODS

Patient data from three randomised, double-blind, placebo-controlled, phase III studies evaluating enzalutamide (AFFIRM, PREVAIL and PROSPER) in patients with castration-resistant prostate cancer were included in this analysis. This post hoc, retrospective study examined the association of statin and metformin on radiographic progression-free survival (rPFS), metastasis-free survival (MFS), toxicity and overall survival (OS). After adjusting for available clinical prognostic variables, multivariate analyses were performed on pooled data from AFFIRM and PREVAIL, all three trials pooled, and each trial individually, to assess differential efficacy in these end-points associated with the baseline use of these medications.

RESULTS

In the multivariate analysis of the individual trials, OS and rPFS/MFS were not significantly influenced by statin or metformin use in AFFIRM or PROSPER. However, in PREVAIL, OS was significantly influenced by statin (hazard ratio [HR] 0.72; 95% confidence interval [CI] 0.59-0.89) and rPFS was significantly influenced by metformin (HR, 0.48; 95% CI 0.34-0.70). In pooled analyses, improved OS was significantly associated with statin use but not metformin use for AFFIRM+PREVAIL trials (HR 0.83; 95% CI 0.72-0.96) and AFFIRM+PREVAIL+PROSPER (HR 0.75; 95% CI 0.66-0.85).

CONCLUSIONS

The association between statin or metformin use and rPFS, MFS and OS was inconsistent across three trials. Analyses of all three trials pooled and AFFIRM+PREVAIL pooled revealed that statin but not metformin use was significantly associated with a reduced risk of death in enzalutamide-treated patients. Additional prospective, controlled studies are warranted.

CLINICAL TRIAL REGISTRATION

AFFIRM (NCT00974311), PREVAIL (NCT01212991) and PROSPER (NCT02003924).

Are Diabetic Patients at Increased Risk for Biochemical Recurrence After Radical Prostatectomy?

Introduction Diabetic patients are at a lower risk for prostate cancer. However, the relationship between diabetes mellitus (DM) and biochemical recurrence (BCR) after radical prostatectomy (RP) is less clear. The goal of our study was to determine diabetes's value as a biochemical recurrence predictor. Materials and methods We conducted a retrospective analysis of 117 patients who had undergone open radical prostatectomy between 1999 and 2021 at our institution. Univariate and multivariate statistical analyses were used to identify factors associated with biochemical recurrence. Results On univariate analysis, factors associated with biochemical recurrence were diabetes (p=0.002), preoperative prostate-specific antigen (PSA) levels (p=0.022), positive digital rectal exam (p=0.035), number of positive biopsy cores (p<0.001), unfavorable intermediate risk group (p=0.014), peri-neural invasion (PNI) on RP specimen (p=0.043), tumor volume (p=0.011), and positive surgical margins (p<0.001). Multivariate analysis showed that factors independently associated with biochemical recurrence were diabetes (p=0.039; OR=2.788), number of positive cores (p=0.016; OR=4.124), and positive surgical margins (p=0.008; OR=3.876). Conclusion A history of diabetes mellitus should be taken into consideration when assessing patients' risk of biochemical recurrence after radical prostatectomy. More research on a larger scale is needed to determine diabetes' value as a biochemical predictor.

Drug Intensification in Future Postoperative Radiotherapy Practice in Biochemically-Relapsing Prostate Cancer Patients

Although salvage prostate bed radiotherapy is highly effective in biochemically-relapsing prostate cancer patients following prostatectomy, relapses remain frequent and improvements are needed. Randomized phase 3 trials have shown the benefit of adding androgen-depriving therapy to irradiation, but not all patients benefit from this combination. Preclinical studies have shown that novel agents targeting the androgen receptor, DNA repair, PI3K/AKT/mTOR pathways, or the hypoxic microenvironment may help increase the response to prostate bed irradiation while minimizing potential side effects. This perspective review focuses on the most relevant molecules that may have an impact when combined with salvage radiotherapy, and underlines the strategies that need to be developed to increase the efficacy of salvage post-prostatectomy radiotherapy in prostate cancer patients.

The multifaceted roles of mitochondria at the crossroads of cell life and death in cancer

Mitochondria are the cytoplasmic organelles mostly known as the "electric engine" of the cells; however, they also play pivotal roles in different biological processes, such as cell growth/apoptosis, Ca²⁺ and redox homeostasis, and cell stemness. In cancer cells, mitochondria undergo peculiar functional and structural dynamics involved in the survival/death fate of the cell. Cancer cells use glycolysis to support macromolecular biosynthesis and energy production ("Warburg effect"); however, mitochondrial OXPHOS has been shown to be still active during carcinogenesis and even exacerbated in drug-resistant and stem cancer cells. This metabolic rewiring is associated with mutations in genes encoding mitochondrial metabolic enzymes ("oncometabolites"), alterations of ROS production and redox biology, and a fine-tuned balance between anti-/proapoptotic proteins. In cancer cells, mitochondria also experience dynamic alterations from the structural point of view undergoing coordinated cycles of biogenesis, fusion/fission and mitophagy, and physically communicating with the endoplasmic reticulum (ER), through the Ca²⁺ flux, at the MAM (mitochondria-associated membranes) levels. This review addresses the peculiar mitochondrial metabolic and structural dynamics occurring in cancer cells and their role in coordinating the balance between cell survival and death. The role of mitochondrial dynamics as effective biomarkers of tumor progression and promising targets for anticancer strategies is also discussed.

The Impact of Metformin Use with Survival Outcomes in Urologic Cancers: A Systematic Review and Meta-Analysis

Background

Conflicting results exist between the potential protective effects of metformin and the prognosis of urologic cancers. This meta-analysis summarized the effects of metformin exposure on the recurrence, progression, cancer-specific survival (CSS), and overall survival (OS) of the three main urologic cancers (kidney cancer, bladder cancer, and prostate cancer).

Methods

We systematically searched PubMed, Embase, Web of Science, Wanfang, and China National Knowledge Infrastructure databases (January 2010 to December 2019), which identified studies regarding metformin users and nonusers with urologic cancers and extracted patient data. A random effect model or fixed effect model was used to analyze hazard ratios (HRs) and 95% confidence intervals (CIs).

Results

Among the 1883 confirmed studies, 27 eligible studies were identified, including 123,212 participants. In prostate cancer, patients using metformin have significant benefits for recurrence (HR = 0.74; 95% CI: 0.61-0.90; P = 0.007; I² = 56%), CSS (HR = 0.74; 95% CI: 0.61-0.91; P = 0.002; I² = 79%), and OS (HR = 0.76; 95% CI: 0.65-0.90; P < 0.001; I² = 86%). Moreover, further subgroup analysis showed that the beneficial effects of metformin may be more significant for patients receiving radical radiotherapy. For kidney cancer, metformin was beneficial for progression (HR = 0.80; 95% CI: 0.65-0.98; P = 0.14; I² = 46%). Analysis revealed that the effect of metformin on the overall survival of kidney cancer patients may be related to nationality (American: HR = 0.76; 95% CI: 0.59-0.98; P = 0.88; I² = 0%). For bladder cancer, no obvious benefits of metformin use were identified. However, subgroup analysis indicated that metformin may improve the recurrence of bladder cancer, but this improvement was only found in patients with a median follow-up time of more than 4 years (HR = 0.43; 95% CI: 0.28-0.67; P = 0.61; I² = 0%).

TAXOMET: A French Prospective Multicentric Randomized Phase II Study of Docetaxel Plus Metformin Versus Docetaxel Plus Placebo in Metastatic Castration-Resistant Prostate Cancer

BACKGROUND

Docetaxel (DOCE) is a standard of care in metastatic castration-resistant prostate cancer (mCRPC). Several retrospective studies suggested a decrease in Prostate Cancer incidence and mortality with metformin (MET). MET has also demonstrated anti-tumor activity in Prostate Cancer preclinical models, with increased apoptosis when added to DOCE. We aimed at exploring the role of MET in combination with DOCE in mCRPC.

PATIENTS AND METHODS

Non-diabetic mCRPC patients were randomly assigned to receive DOCE 75 mg/m² every 21 days + prednisone (5 mg. BID) with either MET 850 mg BID (D+M) or placebo (D+P) up to 10 cycles. Prostate-Specific Antigen (PSA) response ≥50% from baseline was the primary end point. Secondary end points included objective response rate (ORR), progression-free survival (PFS), overall survival (OS), toxicity and quality of life (QoL).

RESULTS

Out of 99 patients were randomized (D+M = 50; D+P = 49) in 10 French centers. The median follow-up was 86 (IQR 73-88) months. The PSA-response rate reached 66% in the D+M arm, but was not different from that observed in the D+P arm (63%, P = 0,94). In the D+M and D+P arms, the ORR was 28% and 24%, the median PFS was 7.8 and 6.0 months and the median OS was 27 and 20 months (ns), respectively. Diarrhea grade I to II was more frequent in the MET arm (66% vs. 43%). No impairment of QoL was observed.

CONCLUSION

MET addition failed to improve the standard DOCE regimen in mCRPC. Further research targeting tumor cell metabolism should be performed.

Fatty Acid Synthesis in Prostate Cancer: Vulnerability or Epiphenomenon?

Tumor metabolism supports the energetic and biosynthetic needs of rapidly proliferating cancer cells and modifies intra- and intercellular signaling to enhance cancer cell invasion, metastasis, and immune evasion. Prostate cancer exhibits unique metabolism with high rates of de novo fatty acid synthesis driven by activation of the androgen receptor (AR). Increasing evidence suggests that activation of this pathway is functionally important to promote prostate cancer aggressiveness. However, the mechanisms by which fatty acid synthesis are beneficial to prostate cancer have not been well defined. In this review, we summarize evidence indicating that fatty acid synthesis drives progression of prostate cancer. We also explore explanations for this phenomenon and discuss future directions for targeting this pathway for patient benefit.

Metformin addition to androgen deprivation therapy effect on cancer prostate patients with type 2 diabetes

AIMS

Patients with prostate cancer (PC) have a higher rate of non-cancer mortality than cancer-related, which could be partially attributed to the treatment they receive. We aimed to evaluate the effect of metformin addition to androgen deprivation therapy (ADT) among cancer prostate patients with type 2 DM.

METHODOLOGY

This prospective, two-arm study included 95 PC patients with type 2 DM who had ADT. The patients were divided into 2 groups: the Metformin group includes 48 patients and the non-metformin group includes 47 patients. We compared the anthropometric, diabetic status; tumour status, survival rate, and biochemical relapse between metformin and non-metformin groups.

RESULTS

We observed significant differences in fold changes of anthropometric parameters including weight, BMI, and waist circumference between both groups. We found significant differences in fold change of PSA levels in metformin groups in comparison with non-metformin groups. Overall survival comparison between metformin users and non-users showed better statistically insignificant survival in the metformin users group. We observed a significantly lower relapse rate in the metformin group in comparison with the non-metformin.

CONCLUSION

Metformin could decrease some of the unfavourable metabolic consequences of ADT. Moreover, Metformin could enhance the tumour-suppressive effect of ADT and decrease the PSA relapse rate.

The First Study Evaluating the Safety of Pre-Surgery Administration of Metformin in Patients with Colorectal and other Gastrointestinal Cancers and Effect on Cancer Stem Cells

BACKGROUND

The cancer stem cell (CSC) hypothesis of tumor genesis suggests that unlike most cancer cells within tumor CSC resist chemotherapy and can regenerate various cell types in tumor thereby causing relapse. Hence drugs that selectively target CSC may offer great promise for cancer therapy especially when combined with chemotherapy. Current treatment options for colorectal cancer (CRC) and other gastrointestinal (GI) tumors rely on combination of surgical resection, cytotoxic and targeted drugs. Recent findings showed that metformin, an ant diabetic drug was associated with a significantly lower risk of CRC (0.63 [0.47 - 0.84]; P = 0.002) in patients with type 2 diabetes. We therefore hypothesize that administration of metformin will reduce CSC.

METHODS

Patients with CRC and other GI cancers undergoing resection were enrolled. Metformin was administered at 500 mg orally twice daily for up to 14 days and terminated 24 hours, prior to planned surgery. Both tumor and normal tissue was procured. Adverse events (AEs) were graded according to NCI CTCAE Version 3.0. Primary objective was to establish the safety of administering metformin prior to resection. Secondary objective was to evaluate the effects of metformin on the expression of CSC markers by measuring relative mRNA levels of CD133, OCT4 and NANOG by RT-PCR and immunohistochemistry.

RESULTS

A total of 10 patients (4 Male; 6 Female) received metformin. Grade 3 AEs included anemia, hypoalbuminemia, alanine aminotransferase elevation, abdominal pain and nausea but none of these were related to metformin. No hypoglycemia and lactic acidosis were observed. No unexpected post-operative complications were witnessed. Comparison of markers of CCSC results showed that expression of CD133, OCT4 and NANOG expression were decreased following metformin.

CONCLUSIONS

Our pilot study showed feasibility of metformin before surgery in GI cancers and indicated impact on CSC. This preliminary data warrants further investigation in a larger randomized placebo-control study to assess these markers and their correlation with survival.

Population-wide impacts of aspirin, statins, and metformin use on prostate cancer incidence and mortality

We evaluated the association between aspirin, statins, and metformin use and prostate cancer (PC) incidence and mortality using a large population-based dataset. 388,760 men who participated in national health screening program in Korea during 2002–2003 were observed from 2004 to 2013. Hazard ratios of aspirin, statins, and metformin use for PC incidence and PC mortality were calculated with adjustment for simultaneous drug use. Cumulative use of each drug was inserted as time-dependent variable with 2-year time windows. Aspirin use ≥ 1.5 year (per 2-year) was associated with borderline decrease in PC mortality when compared to non-users (adjusted hazard ratio [aHR] 0.71, 95% confidence interval [CI] 0.50–1.02). Statins use was not associated with either PC incidence or PC mortality. Metformin ever-use was associated with decreased PC incidence compared with non-diabetics (aHR 0.86, 95% CI 0.77–0.96). Diabetics who were not using metformin or using low cumulative doses had higher PC mortality than non-diabetics (aHR 2.01, 95% CI 1.44–2.81, and aHR 1.70, 95% CI 1.07–2.69, respectively). However, subjects with higher cumulative doses of metformin did not show increased PC mortality. In conclusion, metformin use was associated with lower PC incidence. Use of aspirin and that of metformin among diabetic patients were associated with lower PC mortality.

Repurposing metformin as anticancer drug: Randomized controlled trial in advanced prostate cancer (MANSMED)

BACKGROUND

The proposal of metformin as an anticancer drug has been explored in many types of cancers. Metformin may act synergistically with standard prostate cancer therapies. However, there is still a debate about the effect of metformin on hormone sensitive prostate cancer (HSPC).

PATIENTS AND METHODS

randomized controlled trial. Eligible patients were high risk locally advanced or metastatic HSPC. Patients were randomly assigned to receive either metformin plus standard of care or standard of care alone. The primary endpoint was castration-resistant prostate cancer-free survival (CRPC-FS). The secondary endpoints were overall survival, PSA level and adverse events.

RESULTS

A total number of 124 patients underwent randomization where 62 patients were allocated in each arm. Over a median follow up of 22 months, the CRPC-FS was significantly improved with metformin (29 months, 95% CI 25-33 vs. 20 months 95% CI 16-24; P = 0.01). After subgroup analysis, the addition of metformin improved the CRPC-FS in patients with high risk localized disease (median not reached vs. 25 months, 95% CI 18-31; P = 0.02) and in patients with metastatic low tumor volume disease (median not reached vs. 15 months, 95% CI 5-25; P = 0.009). No significant difference in overall survival or PSA response in both treatment arms (P = 0.1 and 0.5, respectively). Metformin was not associated with significant adverse events apart from grade II diarrhea.

CONCLUSION

Metformin is a safe and low-cost drug. Combining with androgen deprivation therapy improves the outcome in locally advanced or metastatic prostate cancer. Patients with low volume metastatic prostate cancer seem to drive more benefit.

Protective Effects of Metformin Against Biochemical Failure Following Radical Prostatectomy or Radiation Therapy in Localized Prostate Cancer

OBJECTIVE

To assess the impact of metformin on biochemical failure (BF) in localized prostate cancers (PC) treated with radical prostatectomy or radiation therapy.

MATERIALS AND METHODS

About 1449 patients undergoing radical prostatectomy (n = 1338, 92.3%) or radiation therapy (n = 108, 7.5%) for localized PC between July 2007 and January 2020 were evaluated for metformin use, demographic/oncologic characteristics, and biochemical outcomes. Androgen deprivation therapy was utilized per NCCN guidelines. BF rates were assessed overall and at 1, 3, and 5 years. Time to BF was estimated via Kaplan-Meier; logistic regression and Cox proportionate hazards models were generated to adjust for significant differences.

RESULTS

Of 1449 patients, 148 (10.2%) utilized metformin at time of diagnosis, while 1,301 (89.8%) did not. Patients on metformin were significantly older, had higher body mass indexes, and more aggressive disease (Gleason score >7). At a mean ± SD follow-up of 3.6 ± 2.6 years, patients on metformin were less likely to experience BF at later timepoints; however, univariate analysis showed no differences at 1, 3, and 5 years. In multivariate analysis, patients on metformin were significantly less likely to experience BF at 5 years and overall in both treatment groups. In Cox regression, metformin was independently associated with a 40% relative risk reduction in BF.

CONCLUSION

In multivariate analysis, metformin use was associated with a significant risk reduction in BF overall and at 5 years following primary treatment; this trend was not witnessed in univariate analysis. This suggests the need for future investigations of metformin's role in disease-free survival in men with localized PC.

Clinical, Cellular, and Molecular Evidence of the Additive Antitumor Effects of Biguanides and Statins in Prostate Cancer

CONTEXT

Prostate cancer (PCa) is one of the leading causes of cancer-related death among the male population worldwide. Unfortunately, current medical treatments fail to prevent PCa progression in a high percentage of cases; therefore, new therapeutic tools to tackle PCa are urgently needed. Biguanides and statins have emerged as antitumor agents for several endocrine-related cancers.

OBJECTIVE

To evaluate: (1) the putative in vivo association between metformin and/or statins treatment and key tumor and clinical parameters and (2) the direct effects of different biguanides (metformin/buformin/phenformin), statins (atorvastatin/simvastatin/lovastatin), and their combination, on key functional endpoints and associated signalling mechanisms.

METHODS

An exploratory/observational retrospective cohort of patients with PCa (n = 75) was analyzed. Moreover, normal and tumor prostate cells (normal [RWPE-cells/primary prostate cell cultures]; tumor [LNCaP/22RV1/PC3/DU145 cell lines]) were used to measure proliferation/migration/tumorsphere-formation/signalling pathways.

RESULTS

The combination of metformin+statins in vivo was associated to lower Gleason score and longer biochemical recurrence-free survival. Moreover, biguanides and statins exerted strong antitumor actions (ie, inhibition of proliferation/migration/tumorsphere formation) on PCa cells, and that their combination further decreased; in addition, these functional parameters compared with the individual treatments. These actions were mediated through modulation of key oncogenic and metabolic signalling pathways (ie, AR/mTOR/AMPK/AKT/ERK) and molecular mediators (MKI67/cMYC/androgen receptor/cell-cycle inhibitors).

CONCLUSIONS

Biguanides and statins significantly reduced tumor aggressiveness in PCa, with this effect being more potent (in vitro and in vivo) when both compounds are combined. Therefore, given the demonstrated clinical safety of biguanides and statins, our results suggest a potential therapeutic role of these compounds, especially their combination, for the treatment of PCa.

Metformin as a radiosensitiser for pelvic malignancy: A systematic review of the literature

BACKGROUND

The treatment of pelvic malignancies has continued to improve over recent years, with neoadjuvant radiotherapy often considered the gold standard to downstage disease. Radiosensitisers are routinely employed in an attempt to improve response of cancers to radiotherapy. Previous preclinical evidence has suggested a role for metformin, a commonly used drug for type 2 diabetes.

METHOD

A literature search was performed for published full text articles using the PubMed, Cochrane and Scopus databases using the search criteria string 'Metformin' AND ('Radiosensitivity' OR 'radiosensitising' OR 'radiosensitising'). Additional papers were detected by scanning the references of relevant papers. Data were extracted from each study by two authors onto a dedicated proforma. The review was registered on the PROSPERO database (ID: CRD42020199066).

RESULTS

A total of 242 papers were identified, 11 of which were included in this review; an additional 5 papers were obtained from reference searches. Metformin has been demonstrated to reduce cell-viability post-radiotherapy in both rectal and prostate cancer cell lines, with an enhanced effect in tumours with a p53 mutation and increased apoptosis post-radiotherapy for cervical cancer. Clinical trials demonstrate improved tumour and nodal downstaging and pCR rates for rectal cancer using metformin as a radiosensitiser.

CONCLUSION

With an increasing understanding of the underlying mechanism of the effects on metformin prospective studies are required to assess the effect of routine use on cancer related outcomes. Progressive future studies may be better served by the use of predictive biomarker guided treatment to enable identification of the appropriate cohort to target.

Current Status and Application of Metformin for Prostate Cancer: A Comprehensive Review

Metformin, an oral biguanide used for first-line treatment of type 2 diabetes mellitus, has attracted attention for its anti-proliferative and anti-cancer effects in several solid tumors, including prostate cancer (PCa). Liver kinase B1 (LKB1) and adenosine monophosphate-activated protein kinase (AMPK) activation, inhibition of the mammalian target of rapamycin (mTOR) activity and protein synthesis, induction of apoptosis and autophagy by p53 and p21, and decreased blood insulin level have been suggested as direct anti-cancer mechanisms of metformin. Research has shown that PCa development and progression are associated with metabolic syndrome and its components. Therefore, reduction in the risk of PCa and improvement in survival in metformin users may be the results of the direct anti-cancer mechanisms of the drug or the secondary effects from improvement of metabolic syndrome. In contrast, some research has suggested that there is no association between metformin use and PCa incidence or survival. In this comprehensive review, we summarize updated evidence on the relationship between metformin use and oncological effects in patients with PCa. We also highlight ongoing clinical trials evaluating metformin as an adjuvant therapy in novel drug combinations in various disease settings.

Inhibition of EZH2 Enhances the Antitumor Efficacy of Metformin in Prostate Cancer

Upregulation of EZH2 is associated with advanced stage and poor prognosis of prostate cancer; therefore, it is likely to be a promising therapeutic target. Metformin, a drug that has been used to treat type 2 diabetes, was found to have antineoplastic activity in different cancers. Herein, we report that the combination of metformin and the EZH2 inhibitor GSK126 exerts synergistic inhibition on prostate cancer cell growth, both in vitro and in vivo Mechanistically, we identify that metformin can reduce EZH2 expression through upregulating miR-26a-5p, which is antagonized by androgen receptor (AR). Furthermore, we show that AR binds to the promoter of miR-26a-5p and suppresses its transcription. Although metformin can remove AR from the miR-26a-5p promoter, the interaction between AR and EZH2, which usually exists in androgen-refractory prostate cancer cells, strongly impedes the removal. However, GSK126 can inhibit the methyltransferase-dependent interaction between AR and EZH2, thus restoring metformin's efficacy in androgen-refractory prostate cancer cells. Collectively, our finding suggests that the combination of metformin and GSK126 would be an effective approach for future prostate cancer therapy, and particularly effective for AR-positive castration-resistant prostate cancer.

Impact of Concomitant Medications on Biochemical Outcome in Localised Prostate Cancer Treated with Radiotherapy and Androgen Deprivation Therapy

AIMS

Several classes of concomitant medications have been shown to affect oncological outcomes in patients with prostate cancer (PCa). We assessed the association between the use of commonly prescribed concomitant medications and biochemical relapse-free survival (bRFS) in patients with localised PCa treated with radiotherapy and androgen deprivation therapy (ADT).

MATERIALS AND METHODS

A secondary pooled analysis of two phase III randomised trials was carried out. In the first trial, patients with localised PCa with clinical stage T1b-T3, prostate-specific antigen <30 ng/ml and Gleason score ≤7 were treated with radical radiotherapy and 6 months of ADT starting 4 months before or concomitantly with radiotherapy. In the second trial, patients with high-risk PCa were treated with radical radiotherapy and 36 months of ADT with randomisation to three-dimensional conformal or intensity-modulated radiotherapy. Information on concomitant medications was collected from the medical record. Univariable and multivariable Cox regression was used to identify factors associated with bRFS.

RESULTS

Overall, 486 patients were evaluable. The median follow-up was 125 months; 10-year bRFS was 83.7%. On univariable analysis, receipt of metformin was significantly associated with worse bRFS. Ten-year bRFS was 73% and 85% for patients with and without concomitant metformin (adjusted hazard ratio 2.11, 95% confidence interval 1.03-4.33). Similar evidence of an association was observed with sulfonamide-based α1-receptor blockers (adjusted hazard ratio 2.72, 95% confidence interval 1.31-5.66). However, no such association was seen with receipt of quinazoline-based α1-receptor blockers (adjusted hazard ratio 1.09, 95% confidence interval 0.42-2.82). There was no significant association between bRFS and receipt of all other medication classes considered.

CONCLUSIONS

In this population of patients with localised PCa treated with radiotherapy and ADT, receipt of concomitant metformin and sulfonamide-based α1-receptor blockers was associated with inferior biochemical outcome. Randomised trials are required to assess the true effect of these medications on oncological outcomes in localised PCa.

Metformin suppressed tumor necrosis factor-α-induced epithelial-mesenchymal transition in prostate cancer by inactivating the NF-κB signaling pathway

BACKGROUND

Epithelial-mesenchymal transition (EMT) and the tumor micro- environment are involved in tumorigenesis and progression. Tumor necrosis factor-α (TNF-α) is a proinflammatory cytokine in cancer that might be associated with promoting cancer invasion and metastasis. This study aimed to explore the potential effects of metformin on TNF-α-induced EMT in prostate cancer.

METHODS

TNF-α, NF-κB-P65 and E-cadherin were detected in prostate cancer and benign prostatic hyperplasia (BPH) tissues by immunohistochemistry. Prostate cancer PC3 cells were treated with TNF-α with or without metformin. Then, the cell invasion and cell proliferation ability was separately determined by scratch assay and invasion assay. The expression of E-cadherin, N-cadherin, Vimentin, TNF-α, NF-κB-P65, p-IKK and p-IκBα were detected by western blotting and immunofluorescence.

RESULTS

TNF-α and NF-κB-P65 were positively related to higher Gleason scores, but E-cadherin was negatively related to higher Gleason scores. TNF-α significantly increased the migration and invasion ability of prostate cancer cells, and it significantly promoted the expression of N-cadherin, Vimentin, NF-κB-P65, p-IKK and p-IκBα but reduced the expression of E-cadherin. Metformin significantly inhibited TNF-α-induced migration and invasion of prostate cancer cells. Furthermore, metformin decreased TNF-α-induced expression of N-cadherin, Vimentin, NF-κB-P65, p-IKK and p-IκBα but increased the expression of E-cadherin. Moreover, metformin inhibited NF-κB-P65 translocation into the nucleus.

CONCLUSIONS

TNF-α accelerated the EMT process potentially via activation of the NF-κB signaling pathway. Metformin might suppress TNF-α-induced EMT in prostate cancer by inactivating the NF-κB signaling pathway.

The suggested chemopreventive association of metformin with prostate cancer in diabetic patients

PURPOSE

Metformin, an insulin sensitizer, is the most common first-line antidiabetic therapy. There is increasing evidence suggesting metformin can prevent the emergence of prostate cancer (CaP). We aimed to analyze the chemopreventive role of metformin, in conjunction with other putative chemopreventive medications (statins, proton-pump-inhibitors, alpha-blockers, 5-alpha-reductase inhibitors, diabetic medications) in a population-based cohort study.

METHODS

Data were incorporated from the Institute for Clinical and Evaluative Sciences to identify all diabetic men aged 66 and above with prior history of a negative prostate biopsy (PB) between 1994 and 2016, who were not on any of the medications prior to study inclusion. Multivariable Cox regression models with time-dependent covariates were used to assess the association of metformin to CaP diagnosis, subsequent PB, and use of androgen deprivation therapy (ADT). All models were adjusted for age, rurality, comorbidity, and year of study inclusion.

RESULTS

Overall, 2,332 diabetic men were included, with a median follow-up time of 9.4 years (interquartile range 5.4-13.4 years). A total of 2,036 patients (87.3%) received metformin. Compared to non-metformin users, metformin use was associated with decreased CaP diagnosis rate (HR 0.69, 95%CI 0.54-0.88, P = 0.003), lower hazard of undergoing an additional PB (HR 0.64, 95%CI 0.44-0.95, P = 0.03), and receiving ADT (HR 0.72, 95%CI 0.54-0.96, P = 0.003).

CONCLUSION

Men receiving metformin were less likely to have suspected or diagnosed CaP, and in those with CaP, the use of ADT was less common. Ongoing prospective randomized studies will determine if these findings correspond to the suggested associations of metformin in the emergence and/or progression of CaP.

Mechanisms of metformin inhibiting cancer invasion and migration

Cancer currently ranks among the leading causes of death globally. Cancer invasion and metastasis transform locally grown cancers to a systemic and life-threatening disease, which accounts for the most significant challenge in cancer treatment. Recent studies showed that Metformin, the most commonly used first-line oral drug for the treatment of type 2 diabetes (T2DM), could prevent and treat various cancers. Moreover, multiple evidence suggested that metformin inhibited cancer invasion and metastasis, which could improve the prognosis of cancer patients administrated with metformin. To better understand the anti-cancer role of metformin, the present review summarized the potential mechanisms of inhibiting cancer invasion and metastasis by metformin, including AMPK signaling pathway, EMT signaling pathway, epigenetic modification and so on. However, multiple problems remain unresolved and more clinical trials are needed to prove the inhibition of cancer invasion and metastasis by metformin.

Preexisting diabetes, metformin use and long-term survival in patients with prostate cancer

OBJECTIVE

To assess prostate cancer-specific and overall survival in prostate cancer patients with or without preexisting type 2 diabetes mellitus (T2DM) with regards to metformin use.

METHODS

Patients diagnosed with prostate cancer in the Lithuanian population between 2001 and 2005 were identified through the Lithuanian Cancer Registry and followed until 2016, date of death, loss to follow-up or whichever came first. Information regarding the diagnosis of T2DM and antihyperglycemic medications were obtained from the National Health Insurance Fund database. Prostate cancer-specific and overall survival outcomes were analysed using univariate and multivariate Cox proportional hazard models.

RESULTS

Out of 6689 men included, 254 (3.8%) had preexisting T2DM. There were 4807 deaths during follow-up, including 2084 from prostate cancer. No differences were found in prostate cancer-specific survival between men with or without T2DM. The risk of overall mortality was higher (HR = 1.24, 95% CI = 1.07-1.43) in diabetic men. Univariate analysis showed cancer stage at diagnosis and age to be significant predictors of survival. After adjustment for age and stage at diagnosis, there was no difference in prostate-specific survival between non-diabetic patients compared to metformin users or metformin non-users. However, overall survival was lower in T2DM patients, with a higher mortality risk for metformin non-users (HR = 1.63, 95% CI = 1.27-2.10). Prostate cancer-specific mortality risk was insignificantly lower in diabetic men on metformin (HR = 0.74, 95% CI = 0.54-1.02).

CONCLUSION

There was no difference in long-term prostate cancer-specific survival in patients with or without T2DM. Overall survival was lower in T2DM patients not treated with metformin.

Metformin: (future) best friend of the radiation oncologist?

Several molecules are being investigated for their ability to enhance the anti-tumor effect of radiotherapy. The widely prescribed antidiabetic drug metformin has been suggested to possess anti-cancer activity; data indicate that metformin could also enhance radiation sensitivity. The purpose of this review is to summarize current knowledge on the specific effect of metformin in the field of RT, while also discussing the many unknowns that persist. Preclinical models point to multiple mechanisms involved in the radiosensitizing effects of metformin that are mainly linked to mitochondrial complex I inhibition and AMP-activated protein kinase. Transposition of results from bench to bedside will be discussed through the lens of the drug concentration, its potential limits in human settings, and possible alternatives. Clinical data suggest metformin improves progression-free and overall survival in patients for many different cancers treated with RT; nevertheless, the results are not always consistent. The main limitations of the reviewed literature are the retrospective nature of studies, and most of the time, a lack of information on MTF treatment duration and the administered dosages. Despite these limitations, the possible mechanisms of the role of metformin and its utility in enhancing radiotherapy treatments are analyzed. Ongoing clinical trials are also discussed.

Radiotherapy targeting cancer stem cells "awakens" them to induce tumour relapse and metastasis in oral cancer

Radiotherapy is one of the most common treatments for oral cancer. However, in the clinic, recurrence and metastasis of oral cancer occur after radiotherapy, and the underlying mechanism remains unclear. Cancer stem cells (CSCs), considered the “seeds” of cancer, have been confirmed to be in a quiescent state in most established tumours, with their innate radioresistance helping them survive more easily when exposed to radiation than differentiated cancer cells. There is increasing evidence that CSCs play an important role in recurrence and metastasis post-radiotherapy in many cancers. However, little is known about how oral CSCs cause tumour recurrence and metastasis post-radiotherapy. In this review article, we will first summarise methods for the identification of oral CSCs and then focus on the characteristics of a CSC subpopulation induced by radiation, hereafter referred to as “awakened” CSCs, to highlight their response to radiotherapy and potential role in tumour recurrence and metastasis post-radiotherapy as well as potential therapeutics targeting CSCs. In addition, we explore potential therapeutic strategies targeting these “awakened” CSCs to solve the serious clinical challenges of recurrence and metastasis in oral cancer after radiotherapy.

Establishing a novel prediction model for improving the positive rate of prostate biopsy

Background

At present, prostate-specific antigen (PSA) is the primary evaluation index for judging the necessity of prostate cancer (PCa) biopsy. However, there is a high false-positive rate and a low predictive value due to many interference factors. In this study, we tried to find a novel prediction model that could improve the positive rate of prostate biopsy and reduce unnecessary biopsy.

Methods

We retrospectively studied 237 patients, including their age, body mass index (BMI), PSA, prostate volume (PV), prostate imaging-reporting and data system (PI-RADS) v2 score, neutrophil-lymphocyte ratio (NLR), biopsy Gleason score (BGS), and other information. The univariate and multivariate logistic analyses were used to screen out indicators related to PCa. After establishing a prediction formula model, we used receiver operating characteristic (ROC) curves to assess its prediction performance.

Results

Our study found that age, PSA, PI-RADS v2 score, and diabetes significantly correlated with PCa. Based on multivariate logistic regression analysis results, we created the following prediction formula: Y = 2.599 × PI-RADS v2 score + 1.766 × diabetes + 0.052 × age + 1.005 × PSAD - 9.119. ROC curves showed the formula's threshold was 0.3543. The composite formula had an excellent capacity to detect PCa with the area under the curve (AUC) of 0.91. In addition, the composite formula also achieved significantly better sensitivity, specificity, and diagnostic accuracy than PSA, PSA density (PSAD), and PI-RADS v2 score alone.

Conclusions

Our predictive formula predicted performance better than PSA, PSAD, and PI-RADS v2 score. It can thus contribute to the diagnosis of PCa and be used as an indicator for prostate biopsy, thereby reducing unnecessary biopsy.

Individual and joint effects of metformin and statins on mortality among patients with high-risk prostate cancer

BACKGROUND

Pre-clinical studies suggest that metformin and statins may delay prostate cancer (PCa) metastases; however, data in humans are limited. To the best of our knowledge, this is the first human study aimed to quantify the individual and joint effects of statin and metformin use among patients with high-risk PCa.

METHODS

This population-based retrospective cohort study identified patients from the Surveillance, Epidemiology, and End Results (SEER)-Medicare linked database. Exposure to metformin and statins was ascertained from Medicare Prescription Drug Event files. The association with all-cause and PCa mortality were evaluated using Cox proportional hazard model with competing causes of death, where propensity scores were used to adjusted imbalances in covariates across groups.

RESULTS

Based on 12 700 patients with high-risk PCa, statin alone or in combination with metformin was significantly associated with reduced all-cause mortality (Hazard Ratio [HR]: 0.89; 95% Confidence Interval [CI]: 0.83, 0.96; and HR: 0.75; 95% CI, 0.67-0.83, respectively) and PCa mortality (HR, 0.80; 95% CI: 0.69, 0.92) and 0.64; 95% CI, d 0.51-0.81, respectively. The effects were more pronounced in post-diagnostic users: combination use of metformin/statins was associated with a 32% reduction in all-cause mortality (95% CI, 0.57-0.80), and 54% reduction in PCa mortality (95% CI, 0.30-0.69). No significant association of metformin alone was observed with either all-cause mortality or PCa mortality.

CONCLUSIONS

Statin use alone or in combination with metformin was associated with lower all-cause and PCa mortality among high-risk patients, particularly in post-diagnostic settings; further studies are warranted.

Metformin attenuates adhesion between cancer and endothelial cells in chronic hyperglycemia by recovery of the endothelial glycocalyx barrier

BACKGROUND

Epidemiologic studies suggest that diabetes is associated with an increased risk of cancer. Concurrently, clinical trials have shown that metformin, which is a first-line antidiabetic drug, displays anticancer activity. The underlying mechanisms for these effects are, however, still not well recognized.

METHODS

Methods based on atomic force microscopy (AFM) were used to directly evaluate the influence of metformin on the nanomechanical and adhesive properties of endothelial and cancer cells in chronic hyperglycemia. AFM single-cell force spectroscopy (SCFS) was used to measure the total adhesion force and the work of detachment between EA.hy926 endothelial cells and A549 lung carcinoma cells. Nanoindentation with a spherical AFM probe provided information about the nanomechanical properties of cells, particularly the length and grafting density of the glycocalyx layer. Fluorescence imaging was used for glycocalyx visualization and monitoring of E-selectin and ICAM-1 expression.

RESULTS

SCFS demonstrated that metformin attenuates adhesive interactions between EA.hy926 endothelial cells and A549 lung carcinoma cells in chronic hyperglycemia. Nanoindentation experiments, confirmed by confocal microscopy imaging, revealed metformin-induced recovery of endothelial glycocalyx length and density. The recovery of endothelial glycocalyx was correlated with a decrease in the surface expression of E-selectin and ICAM-1.

CONCLUSION

Our results identify metformin-induced endothelial glycocalyx restoration as a key factor responsible for the attenuation of adhesion between EA.hy926 endothelial cells and A549 lung carcinoma cells.

GENERAL SIGNIFICANCE

Metformin-induced glycocalyx restoration and the resulting attenuation of adhesive interactions between the endothelium and cancer cells may account for the antimetastatic properties of this drug.

Prospective Evaluation of Effect of Metformin on Activation of AMP-activated Protein Kinase (AMPK) and Disease Control in a Sub-group Analysis of Patients with GI Malignancies

BACKGROUND

Observational studies have demonstrated association of metformin with reduced cancer incidence and mortality in multiple cancer types, including gastrointestinal (GI) malignancies. Anti-neoplastic effects of metformin are believed through many mechanisms including activation of AMP-activated protein kinase, which controls mammalian target of rapamycin (mTOR) growth regulatory pathway.

METHODS

In a pilot, delayed-start randomized study, non-diabetic patients with GI cancers were randomized to 2 arms, Stage 1: concurrent metformin (500mg twice daily) plus chemotherapy vs. chemotherapy alone followed by cross over to metformin plus chemotherapy arm in Stage 2, while adverse events (DLT) were assessed by CTCAE v.3.0. As a translational correlate, we used phosphorylation of AMPKα at Thr172 to measure AMPK activation by western blot technique in PBMCs isolated from patients before and after receiving M. These levels were correlated with radiological (RECIST 1.1) and tumor marker outcomes by descriptive analysis. In this study, we present the sub-group analysis of patients with GI cancers.

RESULTS

41 patients with GI cancers (colorectal: 22, pancreatic: 12, gastroesophageal: 4, biliary: 2, others: 1) were treated in this trial. Mean duration of metformin therapy was 85 days (range: 9-443). There was no significant difference in grade 3 or above DLT in metformin plus chemotherapy vs. chemotherapy arm (14% vs. 12% respectively). Gel band density analysis on 19 patients showed that 63% patients had increased phosphorylation of AMPKα after metformin (ratio of phospho-AMPKα after and before metformin > 1) with mean = 1.227 (± 0.134). RECIST 1.1 restaging showed disease control in 55% patients and 45% patients had decline in tumor markers. Of note, 60% of patients with disease control also showed increase in phosphorylation of AMKα.

CONCLUSIONS

This group of patients treated with metformin prospectively demonstrates the impact of metformin on AMPKα phosphorylation, and correlates with clinical benefit in patients with GI cancers when metformin was added to systemic chemotherapy of varying types. We aim to perform a dose-escalation of metformin in our next study with additional metabolomics correlates.

A phase I delayed-start, randomized and pharmacodynamic study of metformin and chemotherapy in patients with solid tumors

PURPOSE

Metformin activates AMP-related pathways leading to inactivation of mammalian target of rapamycin (mTOR) and suppression of its downstream effectors, crucial for cancer growth. Epidemiologic studies showed a reduced incidence and improved survival in cancer patients. We conducted a prospective phase I study to assess the safety of metformin in combination with chemotherapy in patients with solid tumors.

METHODS

We conducted a delayed-start randomized trial of non-diabetic patients in two stages. In Stage 1, we randomized patients to two arms: concurrent arm (metformin with chemo) vs. delayed arm (chemo alone). In Stage 2, patients in delayed arm were crossed over to receive metformin. Patients received metformin 500 mg twice daily with chemotherapy to define dose-limiting toxicities (DLTs) in both stages. Secondary endpoints assessed adverse events (AEs) and response rates. Translational correlates included effects of metformin on expression and phosphorylation of 5' adenosine monophosphate-activated protein kinase (AMPK) by western blot in PBMCs.

RESULTS

A total of 100 patients were enrolled (51 in delayed arm vs. 49 concurrent arm). Rate of DLTs in patients receiving metformin with chemotherapy was 6.1% vs. 7.8% in patients receiving chemotherapy alone. DLTs seen with addition of metformin included those associated with established chemo adverse events. No lactic acidosis or hypoglycemia occurred. Restaging showed stable disease in 46% at cessation of metformin. 28% of patients with measurable tumor markers showed improvement. AMPK phosphorylation showed a four- to sixfold increase in AMPK phosphorylation after metformin.

CONCLUSIONS

This is the largest phase I study of metformin combined with chemotherapy, which suggests that metformin can be given safely with chemotherapy, and offers a platform for future studies. Post-metformin increase in AMPK phosphorylation may potentially explain lack of disease progression in nearly half of our patients.

FUNDING

UL1 TR001064.

CLINICAL TRIAL INFORMATION

NCT01442870.

Impact of metformin on disease control and survival in patients with head and neck cancer: a retrospective cohort study

Objective

A number of in vitro and clinical studies have suggested potential antineoplastic effects of metformin. The impact of this medication on outcomes in head and neck cancer is less clear. Our aim was to determine the effect of metformin on outcomes within our large cohort of head and neck cancer patients with Type II Diabetes (T2DM).

Study design

Retrospective cohort study.

Setting

Tertiary Cancer Centre.

Subjects and methods

A retrospective review of individuals with head and neck squamous carcinoma (HNSCC) and T2DM between January 2005 and December 2011 at Princess Margaret Cancer Centre was conducted. Medication history was obtained from surveys at initial presentation and electronic medical record review. Using Cox regression analyses, the association between metformin use and local, regional and distant failures was explored. Subgroup analyses were conducted for oral cavity, oropharynx and larynx.

Results

A total of 329 HNSCC patients with T2DM were identified, including 195 metformin users and 134 non-metformin users. Patients were well-matched in terms of clinical, pathologic, and treatment factors. No difference in local, regional, or distant failure was observed between diabetic metformin users and diabetic non-metformin users for the entire cohort or within subgroup analysis for subsite. No difference between the two groups was observed for overall survival, recurrence-free survival, and disease-specific survival at 5 years.

Conclusion

No association between metformin use and oncologic outcomes were observed in this large cohort of HNSCC patients. Multicenter, prospective studies may be needed to verify previous studies identifying a potential anti-neoplastic effect of this medication.

The beneficial effects of metformin on cancer prevention and therapy: a comprehensive review of recent advances

Metformin is a widely used drug in today’s prescriptions by physicians due to its specific effects in treating and curing type II diabetes. Diabetes is a common disease that may occur throughout human life, and can increase the likelihood of the occurrence of various types of cancer, such as colon, rectum, pancreas and liver cancers, compared to non-diabetic patients. Metformin inhibits mTOR activity by activating ATM (ataxia telangiectasia mutated) and LKB1 (liver kinase B1) and then adenosine monophosphate-activated kinase (AMPK), and thus prevents protein synthesis and cell growth. Metformin can activate p53 by activating AMPK and thereby ultimately stop the cell cycle. Given the potential of metformin in the treatment of cancer, it can be used in radiotherapy, chemotherapy and to improve the response to treatment in androgen derivatives (ADT), and also, according to available evidence, metformin can also be used to prevent various types of cancers. Generally, metformin can: 1) reduce the incidence of cancers, 2) reduce the mortality from cancers, 3) increase the response to treatment in cancer cells when using radiotherapy and chemotherapy, 4) optimize tumor movement and reduce the malignancy, 5) reduce the likelihood of relapse, and 6) reduce the damaging effects of ADT. Therefore, this drug can be used as a complementary therapeutic agent for cancer treatment and prevention. In this review, we have summarized the data from various experimental and clinical studies and highlight the possible potential effects of metformin on cancer therapeutic responses.

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Metabolic Alterations, Aggressive Hormone-Naïve Prostate Cancer and Cardiovascular Disease: A Complex Relationship

Background: Epidemiological studies suggest a possible relationship between metabolic alterations, cardiovascular disease and aggressive prostate cancer, however, no clear consensus has been reached. Objective: The aim of the study was to analyze the recent literature and summarize our experience on the association between metabolic disorders, aggressive hormone-naïve prostate cancer and cardiovascular disease. Method: We identified relevant papers by searching in electronic databases such as Scopus, Life Science Journals, and Index Medicus/Medline. Moreover, we showed our experience on the reciprocal relationship between metabolic alterations and aggressive prostate cancer, without the influence of hormone therapy, as well the role of coronary and carotid vasculopathy in advanced prostate carcinoma. Results: Prostate cancer cells have an altered metabolic homeostatic control linked to an increased aggressivity and cancer mortality. The absence of discrimination of risk factors as obesity, systemic arterial hypertension, diabetes mellitus, dyslipidemia and inaccurate selection of vascular diseases as coronary and carotid damage at initial diagnosis of prostate cancer could explain the opposite results in the literature. Systemic inflammation and oxidative stress associated with metabolic alterations and cardiovascular disease can also contribute to prostate cancer progression and increased tumor aggressivity. Conclusions: Metabolic alterations and cardiovascular disease influence aggressive and metastatic prostate cancer. Therefore, a careful evaluation of obesity, diabetes mellitus, dyslipidemia, systemic arterial hypertension, together with a careful evaluation of cardiovascular status, in particular coronary and carotid vascular disease, should be carried out after an initial diagnosis of prostatic carcinoma.

Diabetes in the practice of otolaryngology

Diabetes mellitus is the most common endocrine disease, characterized by chronic hyperglycemia. The hyperglycemic milieu leads to endothelial injury in blood vessels of variant size, which results in microangiopathy and macroangiopathy (atherosclerosis). Consequential ischemia of nerves and hyperglycemia by itself lead to nerve degeneration and generalized neuropathy, affecting most often the sensory peripheral nerves and the autonomic nervous system. Auditory, vestibular and olfactory sensorium may be compromised by DM. People with DM have an increased susceptibility to infection, as a result of neutrophil dysfunction and impaired humoral immunity. Therefore DM predisposes to certain infectious diseases, such as fungal sinusitis or malignant otitis externa, which are rare in general population. Recovery from infections or from injuries may be compromised by coexisting DM. In this review we discuss complications of DM in the head and neck region. Otolaryngologists and general practitioners should be alert to specific conditions related to DM and be minded of the relevant complications and consequences.