A Multicenter Double-blind Phase II Study of Metformin With Gefitinib as First-line Therapy of Locally Advanced Non–Small-cell Lung Cancer

The role of AMPK-dependent pathways in cellular and molecular mechanisms of metformin: a new perspective for treatment and prevention of diseases

Metformin can suppress gluconeogenesis and reduce blood sugar by activating adenosine monophosphate-activated protein kinase (AMPK) and inducing small heterodimer partner (SHP) expression in the liver cells. The main mechanism of metformin's action is related to its activation of the AMPK enzyme and regulation of the energy balance. AMPK is a heterothermic serine/threonine kinase made of a catalytic alpha subunit and two subunits of beta and a gamma regulator. This enzyme can measure the intracellular ratio of AMP/ATP. If this ratio is high, the amino acid threonine 172 available in its alpha chain would be activated by the phosphorylated liver kinase B1 (LKB1), leading to AMPK activation. Several studies have indicated that apart from its significant role in the reduction of blood glucose level, metformin activates the AMPK enzyme that in turn has various efficient impacts on the regulation of various processes, including controlling inflammatory conditions, altering the differentiation pathway of immune and non-immune cell pathways, and the amelioration of various cancers, liver diseases, inflammatory bowel disease (IBD), kidney diseases, neurological disorders, etc. Metformin's activation of AMPK enables it to control inflammatory conditions, improve oxidative status, regulate the differentiation pathways of various cells, change the pathological process in various diseases, and finally have positive therapeutic effects on them. Due to the activation of AMPK and its role in regulating several subcellular signalling pathways, metformin can be effective in altering the cells' proliferation and differentiation pathways and eventually in the prevention and treatment of certain diseases.

Metformin and Cancer, an Ambiguanidous Relationship

The deregulation of energetic and cellular metabolism is a signature of cancer cells. Thus, drugs targeting cancer cell metabolism may have promising therapeutic potential. Previous reports demonstrate that the widely used normoglycemic agent, metformin, can decrease the risk of cancer in type 2 diabetics and inhibit cell growth in various cancers, including pancreatic, colon, prostate, ovarian, and breast cancer. While metformin is a known adenosine monophosphate-activated protein kinase (AMPK) agonist and an inhibitor of the electron transport chain complex I, its mechanism of action in cancer cells as well as its effect on cancer metabolism is not clearly established. In this review, we will give an update on the role of metformin as an antitumoral agent and detail relevant evidence on the potential use and mechanisms of action of metformin in cancer. Analyzing antitumoral, signaling, and metabolic impacts of metformin on cancer cells may provide promising new therapeutic strategies in oncology.

Benefit from Adjuvant TKIs Versus TKIs Plus Chemotherapy in EGFR-Mutant Stage III-pN2 Lung Adenocarcinoma

BACKGROUND

Recent studies have demonstrated benefits from adjuvant tyrosine-kinase inhibitors (TKIs) compared with chemotherapy in non-small cell lung cancer. We launched a multi-center retrospective study to evaluate the efficacy and toxicity of adjuvant TKIs with or without chemotherapy in epidermal growth factor receptor (EGFR)-mutant stage III-pN2 lung adenocarcinoma.

METHODS

Two hundred and seventy-four consecutive cases with stage III-pN2 lung adenocarcinoma and complete resection have been investigated. Clinic-pathologic characteristics, adjuvant treatments, long-term survivals, and toxicities were documented. Risk factors of distant metastasis-free survival (DMFS), disease-free survival (DFS), and overall survival (OS) were evaluated.

RESULTS

There were 52 (19.0%) patients treated with adjuvant TKIs alone, 199 (72.6%) with adjuvant chemotherapy alone, and 23 (8.4%) with both. After a median follow-up time of 29 months, the two-year DMFS, DFS, and OS was 61.2%, 54.1%, and 91.2%, respectively. According to univariable analyses, the risk factors were lymphovascular invasion (p < 0.001), extranodal extension (p = 0.005), and adjuvant systemic therapy (p = 0.006) for DMFS, EGFR mutation type (p = 0.025), lymphovascular invasion (p = 0.013), extranodal extension (p = 0.004), and adjuvant systemic therapy (p < 0.001) for DFS, and EGFR mutation type (p < 0.001) for OS. Multivariable analyses indicated that the independent prognostic factors were adjuvant systemic therapy (TKIs vs. TKIs+chemotherapy, Harzard ratio (HR) = 0.40; p = 0.036; TKIs vs. chemotherapy, HR = 0.38; p = 0.004), lymphovascular invasion (yes vs. no, HR = 2.22; p = 0.001) for DMFS, and adjuvant systemic therapy (TKIs vs. TKIs+chemotherapy, HR = 0.42; p = 0.034; TKIs vs. chemotherapy, HR = 0.33; p < 0.001) for DFS. No significant difference was found in the incidence of Grade 3-4 toxicities between groups (p = 0.445).

CONCLUSIONS

Adjuvant TKIs might be a beneficial choice compared with adjuvant chemotherapy or combination systemic treatments.

Anticancer mechanisms of metformin: A review of the current evidence

Metformin, a US Food and Drug Administration-approved "star" drug used for diabetes mellitus type 2, has become a topic of increasing interest to researchers due to its anti-neoplastic effects. Growing evidence has demonstrated that metformin may be a promising chemotherapeutic agent, and several clinical trials of metformin use in cancer treatment are ongoing. However, the anti-neoplastic effects of metformin and its underlying mechanisms have not been fully elucidated. In this review, we present the newest findings on the anticancer activities of metformin, and highlight its diverse anticancer mechanisms. Several clinical trials, as well as the limitations of the current evidence are also demonstrated. This review explores the crucial roles of metformin and provides supporting evidence for the repurposing of metformin as a treatment of cancer.

Metformin: current clinical applications in nondiabetic patients with cancer

Metformin is one of the most commonly used first-line oral medications for type 2 diabetes mellitus. Multiple observational studies, reviewed in numerous systematic reviews, have shown that metformin treatment may not only reduce the risk of cancer but may also improve the efficacy of cancer treatment in diabetic patients. Recent studies have been conducted to determine whether a similar protective effect can be demonstrated in nondiabetic cancer patients. However, the results are controversial. The potential optimal dose, schedule, and duration of metformin treatment and the heterogeneity of histological subtypes and genotypes among cancer patients might contribute to the different clinical benefits. In addition, as the immune property of metformin was investigated, further studies of the immunomodulatory effect of metformin on cancer cells should also be taken into account to optimize its clinical use. In this review, we present and discuss the latest findings regarding the anticancer potential of metformin in nondiabetic patients with cancer.

Combination of Metformin and Gefitinib as First-Line Therapy for Nondiabetic Advanced NSCLC Patients with EGFR Mutations: A Randomized, Double-Blind Phase II Trial

PURPOSE

Preclinical and retrospective studies suggested a role for metformin in sensitizing patients who have diabetes with non-small cell lung cancer (NSCLC) to EGFR tyrosine kinase inhibitors (TKIs). We therefore examined its effects in combination with gefitinib in patients without diabetes harboring EGFR mutations (EGFRm).

PATIENTS AND METHODS

A total of 224 patients without diabetes with treatment-naïve stage IIIB-IV EGFRm NSCLC were randomly assigned in a 1:1 ratio to receive gefitinib plus either metformin or placebo. The primary endpoint was progression-free survival (PFS) rate at 1 year and secondary endpoints included overall survival (OS), PFS, objective response rate (ORR), and safety. Serum levels of IL6 were also examined in an exploratory analysis.

RESULTS

The median duration of follow-up was 19.15 months. The estimated 1-year PFS rates were 41.2% [95% confidence interval (CI), 30.0-52.2] with gefitinib plus metformin and 42.9% (95% CI, 32.6-52.7) with gefitinib plus placebo (P = 0.6268). Median PFS (10.3 months vs. 11.4 months) and median OS (22.0 months vs. 27.5 months) were numerically lower in the metformin group, while ORRs were similar between the two arms (66% vs. 66.7%). No significant treatment group differences were detected across all subgroups with respect to PFS, including those with elevated levels of IL6. Metformin combined with gefitinib resulted in a remarkably higher incidence of diarrhea compared with the control arm (78.38% vs. 43.24%).

CONCLUSIONS

Our study showed that addition of metformin resulted in nonsignificantly worse outcomes and increased toxicity and hence does not support its concurrent use with first-line EGFR-TKI therapy in patients without diabetes with EGFRm NSCLC.

Metformin promotes survivin degradation through AMPK/PKA/GSK-3β-axis in non-small cell lung cancer

Metformin, a first-line antidiabetic drug, has been reported with anticancer activities in many types of cancer. However, its molecular mechanisms remain largely unknown. As a member of inhibitor of apoptosis proteins, survivin plays an important role in the regulation of cell death. In the present study, we investigated the role of survivin in metformin-induced anticancer activity in non-small cell lung cancer in vitro. Metformin mainly induced apoptotic cell death in A549 and H460 cell lines. It remarkably suppressed the expression of survivin, decreased the stability of this protein, then promoted its proteasomal degradation. Moreover, metformin greatly suppressed protein kinase A (PKA) activity and induced its downstream glycogen synthase kinase 3β (GSK-3β) activation. PKA activators, both 8-Br-cAMP and forskolin, significantly increased the expression of survivin. Consistently both GSK-3β inhibitor LiCl and siRNA restored the expression of survivin in lung cancer cells. Furthermore, metformin induced adenosine 5'-monophosphate-activated protein kinase (AMPK) activation. Suppression of the activity of AMPK with Compound C reversed the degradation of survivin induced by metformin, and meanwhile, restored the activity of PKA and GSK-3β. These results suggest that metformin kills lung cancer cells through AMPK/PKA/GSK-3β-axis-mediated survivin degradation, providing novel insights into the anticancer effects of metformin.

Metformin Use and Lung Cancer Risk in Diabetic Patients: A Systematic Review and Meta-Analysis

Background

Antidiabetic medications (ADMs) can alter the risk of different types of cancer, but the relationship between lung cancer incidence and metformin remains controversial. Our aim was to quantitatively estimate the relationship between incidences of lung cancer and metformin in patients with diabetes in this meta-analysis.

Methods

We performed a search in PubMed, Embase, ISI Web of Science, and Cochrane Library until September 20, 2017. The odds ratio (OR), relative risk (RR) or hazard ratio (HR), and 95% confidence interval (95% CI) were estimated using the random-effect model. The Newcastle-Ottawa Scale (NOS) was used to assess the study quality.

Results

A total of 13 studies (10 cohort studies and 3 case-control studies) were included in the meta-analysis. Compared to nonmetformin users, metformin probably decreased lung cancer incidence in diabetic patients (RR = 0.89; 95% CI, 0.83-0.96; P = 0.002) with significant heterogeneity (Q = 35.47, I² = 66%, P = 0.0004). Subgroup analysis showed that cohort studies (RR = 0.91; 95% CI, 0.85-0.98; P = 0.008), location in Europe (RR = 0.90; 95% CI, 0.86-0.94; P < 0.0001), the control drug of the sulfonylurea group (RR = 0.91; 95% CI, 0.86-0.96; P = 0.001), and adjusting for smoking (RR = 0.86; 95% CI, 0.75-1.00; P = 0.05) may be related to lower lung cancer risk. No significant publication bias was detected using a funnel plot.

Conclusion

Metformin use was related to a lower lung cancer risk in diabetic patients compared to nonusers, but this result was retrieved from observational studies and our findings need more well-designed RCTs to confirm the association.

Metformin induces apoptotic cytotoxicity depending on AMPK/PKA/GSK-3β-mediated c-FLIPL degradation in non-small cell lung cancer

Background

Metformin, a first-line antidiabetic drug, has recently been reported with anticancer activities in various cancers; however, the underlying mechanisms remain elusive. The aim of the present study was to investigate the role of cellular FADD-like IL-1β-converting enzyme (FLICE)-inhibitory protein large (c-FLIP_L) in metformin-induced anticancer activity in non-small cell lung cancer (NSCLC) in vitro.

Materials and methods

Cell viability was measured by MTT assay. Quantitative real-time PCR was carried out to detect the level of mRNA of related genes. The expression of related proteins was detected by Western blot. siRNA was used to silence the expression of targeted proteins.

Results

Metformin significantly suppressed proliferation of both A549 and H460 cells in a dose-dependent manner. Mechanistic studies suggested that metformin killed NSCLC cells by inducing apoptotic cell death. Moreover, metformin greatly inhibited c-FLIP_L expression and then promoted its degradation. Furthermore, metformin significantly activated Adenosine 5'-monophosphate (AMP)-activated protein kinase (AMPK) and its downstream glycogen synthase kinase 3beta (GSK-3β), block the expression of AMPK, and GSK-3β with siRNA partially reversed metformin-induced cytotoxicity and restored the expression of c-FLIP_L in lung cancer cells. Metformin also suppressed the activity of AMPK downstream protein kinase A (PKA), PKA activators, both 8-Br-cAMP and forskolin, greatly increased c-FLIP_L expression in NSCLC cells.

Conclusion

This study provided evidence that metformin killed NSCLC cells through AMPK/PKA/GSK-3β axis-mediated c-FLIP_L degradation.

Novel application of metformin combined with targeted drugs on anticancer treatment

The success of targeted drug therapies for treating cancer patients has attracted broad attention both in the academic community and social society. However, rapidly developed acquired resistance is becoming a newly recognized major challenge to the continuing efficiency of these therapies. Metformin is a well‐known natural compound with low toxicity derived from the plant French lilac. Our previous work has highlighted research progress of the combination of clinically applied chemotherapies and metformin by different mechanisms. We have also launched a study to combine metformin with the small molecule targeted drug gefitinib to treat bladder cancer using intravesical administration. Thus, in this minireview, we summarize recent achievements combining metformin with various targeted therapies. This work directs the potential clinical future by selecting available cancer patients and providing precise medicine by the combination of metformin and targeted drugs to overcome resistance and enhance therapeutic efficacies.

The prognostic value of metformin for advanced non-small cell lung cancer: a systematic review and meta-analysis

Background

The prognostic value of Metformin for concurrent non-small cell lung cancer (NSCLC) has been controversial in previous individual studies and meta-analyses. In order to further investigate the value of this medication, we conducted a systematic review and meta-analysis for patients with advanced or inoperable NSCLC.

Methods

We searched articles from PubMed, Scopus and Web of Science databases; the time interval was from the inception date of the databases to 1 September 2017. Inclusion criteria for eligible studies were: advanced or inoperable NSCLC; Metformin as an experimental group, and non-Metformin usage as a control group; progression-free survival (PFS) or overall survival (OS) as the outcome, with available hazard ratio (HR). Data synthesis was conducted based on the random-effect model.

Results

From a total of 97 articles in databases, we included seven eligible studies. Among them, only one study compared Metformin usage and non-Metformin usage for NSCLC patients who didn't have diabetes mellitus (DM): no significant difference was found in either OS or PFS. The remaining six studies compared Metformin usage and non-Metformin usage for patients with concurrent NSCLC and DM: according to meta-analysis, significantly prolonged OS was found in Metformin usage rather than non-Metformin usage [pooled HR =0.87 (0.77-0.99), P=0.04]; no significant difference was indicated in PFS [pooled HR =0.85 (0.67-1.07), P=0.16]. In subgroup analysis, among patients with late-stage NSCLC and DM, significant difference was found, regardless of OS [pooled HR =0.81 (0.70-0.94), P<0.01] or PFS [pooled HR =0.71 (0.58-0.88), P<0.01]. However, among patients with local advanced NSCLC and DM, there was no significant difference [OS: pooled HR =1.05 (0.79-1.40), P=0.74; PFS: pooled HR =0.94 (0.68-1.32), P=0.74].

Conclusions

The prognostic value of Metformin for concurrent late-stage NSCLC and DM was demonstrated. It deserves further confirmation and explanation.

Metformin for non-small cell lung cancer patients: Opportunities and pitfalls

Despite exciting advances of the anticancer armamentarium in the recent years, mortality of non-small cell lung cancer (NSCLC) remains high and novel treatments are requisite. Therapy intensification is explored with promising, but expensive and potentially toxic new compounds. Repositioning already existing drugs for cancer treatment could save money and improve patient outcomes in specific contexts. Observational data suggest that use of the standard antidiabetic agent metformin decreases lung cancer incidence and mortality. Several basic researches have shown various anticancer effects of metformin, acting both on the glycolytic metabolism and on the tumoral immune microenvironment. Synergistic actions of metformin with antitumoral agents in preclinical NSCLC models have then been highlighted. Recent retrospective studies advocated improved outcomes in NSCLC diabetic patients receiving metformin with chemoradiotherapy or systemic compounds (including conventional platinum-based chemotherapy and EGFR tyrosine kinase inhibitors). Several prospective randomized trials are therefore currently assessing the addition of metformin to standard therapy in non-diabetic lung cancer patients. This article reviews promises and possible limitations of concurrent metformin used as an anticancer agent in NSCLC patients.

Impact of metformin on gastric adenocarcinoma survival: A Belgian population based study

BACKGROUND

Preclinical studies have shown anticancer activities of metformin in gastric cancer and a recent epidemiological study showed a decrease in recurrence and mortality of gastric cancer in metformin users. This study aimed to assess the impact of metformin on gastric cancer survival in diabetic patients at a Belgian population level.

METHODS

We conducted an observational, population-based study by linking data of the Belgian Cancer Registry with medical claims data coming from the health insurance companies for patients diagnosed with stage I to III gastric adenocarcinoma between 2006 and 2012. Information on gastric cancer-specific deaths was retrieved from mortality records collected by regional governments. Time-dependent Cox regression models were used to calculate hazard ratios (HRs) and 95% confidence intervals (CI) for overall survival (OS) and cancer-specific mortality (CSS).

RESULTS

In our population of 371 patients, a reduction in all-cause mortality was observed in metformin users (adjusted HR = 0.73, 95% CI: [0.52; 1.01], p = 0.06) but not for cancer specific mortality (adjusted HR = 0.86, 95% CI: [0.56; 1.33], p = 0.50). Pre-diagnosis exposure to metformin was associated with a significant improvement in OS (adjusted HR = 0.75, 95% CI: [0.57; 0.98], p = 0.04) that was not significant for CSS (adjusted HR = 0.89, 95% CI: [0.62; 1.28], p = 0.52). Moreover, no dose-response relationship between metformin use and either all-cause or cancer-specific mortality was observed.

CONCLUSION

In the first population based study of metformin use in gastric cancer adenocarcinoma patients with previous diabetes, our findings suggest that metformin use might improve overall mortality. However, no such association was found for cancer-specific survival. Additional studies in other populations are required.

Precision oncology: neither a silver bullet nor a dream

Precision oncology is not an illusion, nor is it the magic bullet that will eradicate all cancers. Precision oncology is simply another weapon in our growing armament against cancer. Rather than honing in on the failures of a relatively young field, one should advocate for integrating its successes into widespread clinical practice, especially for indications, such as: ABL, ALK, BRAF, BRCA1, BRCA2, EGFR, KIT, KRAS, PDGFRA, PDGFRB, ROS1, BCR-ABL, FLT3 and ROS1, where aberrations have been shown to alter responses to US FDA approved drugs - that is, level 1 data. Moreover, to truly assess the promise of precision oncology, we must first begin by defining our expectations for this field. Importantly, we must recognize that the conception of precision oncology arose as an antithesis of the 'one-size fits all' cancer therapeutics approach. Consequently, tools used for evaluating these conventional, large-scale trials, are not directly transferable for assessing nonconventional, smaller-scale trials needed for evaluating precision oncology. Hence, a thorough vetting of precision oncology as another tool of the trade, must first begin by reassessing our expectations for this field, as well as current clinical trial designs and end point measurements. Importantly, we must recognize that most targeted therapy approaches are in their infancy, with only monotherapy approaches being assessed and combination therapies likely being necessary to fulfill the promise of precision oncology.