NCI Resources for Cancer Immunoprevention Research.

Cancer prevention and early detection, the first two of the eight primary goals of the National Cancer Plan released in April 2023, are at the forefront of the nation's strategic efforts to reduce cancer incidence and mortality. The Division of Cancer Prevention (DCP) of the NCI is the federal government's principal component devoted to promoting and supporting innovative cancer prevention research. Recent advances in tumor immunology, cancer immunotherapy, and vaccinology strongly suggest that the host immune system can be effectively harnessed to elicit protective immunity against the development of cancer, that is, cancer immunoprevention. Cancer immunoprevention may be most effective if the intervention is given before or early in the carcinogenic process while the immune system remains relatively uncompromised. DCP has increased the emphasis on immunoprevention research in recent years and continues to expand program resources and interagency collaborations designed to facilitate research in the immunoprevention field. These resources support a wide array of basic, translational, and clinical research activities, including discovery, development, and validation of biomarkers for cancer risk assessment and early detection (Early Detection Research Network), elucidation of biological and pathophysiological mechanistic determinants of precancer growth and its control (Translational and Basic Science Research in Early Lesions), spatiotemporal multiomics characterization of precancerous lesions (Human Tumor Atlas Network/Pre-Cancer Atlas), discovery of immunoprevention pathways and immune targets (Cancer Immunoprevention Network), and preclinical and clinical development of novel agents for immunoprevention and interception (Cancer Prevention-Interception Targeted Agent Discovery Program, PREVENT Cancer Preclinical Drug Development Program, and Cancer Prevention Clinical Trials Network).

Primary Prevention and Interception Studies in RAS-Mutated Tumor Models Employing Small Molecules or Vaccines.

Therapeutic targeting of RAS-mutated cancers is difficult, whereas prevention or interception (treatment before or in the presence of preinvasive lesions) preclinically has proven easier. In the A/J mouse lung model, where different carcinogens induce tumors with different KRAS mutations, glucocorticoids and retinoid X receptor (RXR) agonists are effective agents in prevention and interception studies, irrespective of specific KRAS mutations. In rat azoxymethane-induced colon tumors (45% KRAS mutations), cyclooxygenase 1/2 inhibitors and difluoromethylornithine are effective in preventing or intercepting KRAS-mutated or wild-type tumors. In two KRAS-mutant pancreatic models multiple COX 1/2 inhibitors are effective. Furthermore, combining a COX and an EGFR inhibitor prevented the development of virtually all pancreatic tumors in transgenic mice. In the N-nitroso-N-methylurea-induced estrogen receptor-positive rat breast model (50% HRAS mutations) various selective estrogen receptor modulators, aromatase inhibitors, EGFR inhibitors, and RXR agonists are profoundly effective in prevention and interception of tumors with wild-type or mutant HRAS, while the farnesyltransferase inhibitor tipifarnib preferentially inhibits HRAS-mutant breast tumors. Thus, many agents not known to specifically inhibit the RAS pathway, are effective in an organ specific manner in preventing or intercepting RAS-mutated tumors. Finally, we discuss an alternative prevention and interception approach, employing vaccines to target KRAS.

Emerging Trends in Cancer Prevention Agent Development.

Advances in omics and immunology over the past 20 years have revolutionized the approach to cancer prevention, with the goal now focused on identifying populations at higher risk for developing cancer in their lifetime as a result of either extensive exposure to environmental carcinogens or harboring precancer lesions or inherited genetic mutations that predispose them to specific types of cancer(s). Thus, the naïve idea that cancer could be "prevented" in the general population has evolved to a more practical approach based on the understanding that the target population for preventive agents will be individuals who already have alterations, in gene pathways, whether inherited or environmentally caused, and the goal will be to "intercept" these lesions at the earliest stages in the path from an initial genetic lesion to full-blown cancer. The Division of Cancer Prevention of the National Cancer Institute and the Office of Disease Prevention at the National Institutes of Health recently sponsored the second biennial "Translational Advances in Cancer Preventive Agent Development Meeting," held virtually from September 7-9th. In this Meeting Report, we highlight the scientific sessions of this meeting that covered the most recent advances in preventive agent development that also highlighted these rapidly emerging trends in this research area.

Inflammation as a chemoprevention target in asbestos-induced malignant mesothelioma.

Malignant mesothelioma (MM) is an incurable cancer of the serosal lining that is often caused by exposure to asbestos. Therefore, novel agents for the prevention and treatment of this disease are urgently needed. Asbestos induces the release of pro-inflammatory cytokines such as IL-1ß and IL-6, which play a role in MM development. IL-6 is a component of the JAK-STAT3 pathway that contributes to inflammation-associated tumorigenesis. Glycoprotein 130 (gp130), the signal transducer of this signaling axis, is an attractive drug target because of its role in promoting neoplasia via the activation of downstream STAT3 signaling. The anticancer drug, SC144, inhibits the interaction of gp130 with the IL-6 receptor (IL6R), effectively blunting signaling from this inflammatory axis. To test whether the inflammation-related release of IL-6 plays a role in the formation of MM, we evaluated the ability of SC144 to inhibit asbestos-induced carcinogenesis in a mouse model. The ability of sulindac and anakinra, an IL6R antagonist/positive control, to inhibit MM formation in this model was tested in parallel. Asbestos-exposed Nf2+/-;Cdkn2a+/- mice treated with SC144, sulindac or anakinra showed significantly prolonged survival compared to asbestos-exposed vehicle-treated mice. STAT3 activity was markedly decreased in MM specimens from SC144-treated mice. Furthermore, SC144 inhibited STAT3 activation by IL-6 in cultured normal mesothelial cells, and in vitro treatment of MM cells with SC144 markedly decreased the expression of STAT3 target genes. The emerging availability of newer, more potent SC144 analogs showing improved pharmacokinetic properties holds promise for future trials, benefitting individuals at high risk of this disease.

Pulmonary Aerosol Delivery of Let-7b microRNA Confers a Striking Inhibitory Effect on Lung Carcinogenesis through Targeting the Tumor Immune Microenvironment.

MicroRNAs are potential candidates for lung cancer prevention and therapy. A major limitation is the lack of an efficient delivery system to directly deliver miRNA to cancer cells while limiting systemic exposure. The delivery of miRNA via inhalation is a potential strategy for lung cancer prevention in high-risk individuals. In this study, the authors investigate the efficacy of aerosolized let-7b miRNA treatment in lung cancer prevention. Let-7b shows significant inhibition of B[a]P-induced lung adenoma with no detectable side effects. Single-cell RNA sequencing of tumor-infiltrating T cells from primary tumors reveals that Let-7b post-transcriptionally suppresses PD-L1 and PD-1 expression in the tumor microenvironment, suggesting that let-7b miRNAs may promote antitumor immunity in vivo. Let-7b treatment decreases the expression of PD-1 in CD8+ T cells and reduces PD-L1 expression in lung tumor cells. The results suggest that this aerosolized let-7b mimic is a promising approach for lung cancer prevention, and that the in vivo tumor inhibitory effects of let-7b are mediated, at least in part, by immune-promoting effects via downregulating PD-L1 in tumors and/or PD-1 on CD8+ T cells. These changes potentiate antitumor CD8+ T cell immune responses, and ultimately lead to tumor inhibition.

Effects of High-Fructose Diet vs. Teklad Diet in the MNU-Induced Rat Mammary Cancer Model: Altered Tumorigenesis, Metabolomics and Tumor RNA Expression.

Epidemiology, clinical and experimental animal studies suggest high fructose diets are detrimental to metabolic status and may contribute to tumor development. This due to increased obesity and metabolic syndrome, known risk factors for many types of cancer. We compared tumor development in N-methyl-N-nitrosourea (MNU)-treated rats fed either a high (60%)-fructose diet (HFD) or a standard diet (SD). Female Sprague-Dawley rats at 43 days of age (DOA) were fed a SD or HFD followed by administration of MNU at 50 DOA. Rats were palpated weekly and sacrificed at 190 DOA. MNU-treated rats on HFD exhibited decreased tumor latency and roughly a two-fold increase in tumor multiplicity. RNA-Seq on frozen tumors (SD vs. HFD rats) showed altered expression of approximately 10% of genes (P < 0.05). When examined by Ingenuity Pathway Analysis, multiple highly significant pathways were identified including A) mechanisms of cancer, B) Wnt pathway, C) immune response (e.g., "Th1 and Th2 activation" and "antigen presentation") and D) LXR/RXR nuclear receptor. These generalized pathways were indirectly confirmed by alterations of various interrelated disease pathways (epithelial cancers, T cell numbers and apoptosis). In a second study, serum was collected from rats on the HFD or SD pre-MNU and at the time of sacrifice. Metabolomics revealed that the HFD yielded: A) increased levels of fructose, B) increases of various monoglycerols, C) reduced levels of various diacylglycerols and oxygenated inflammatory lipids (9 and 13 HODE and 12,13 DHOME) and D) increased levels of secondary bile acids (hyodeoxycholate and 6-oxolithocholate), which may reflect microbiome changes. These metabolomic changes, which are distinct from those on a high-fat diet, may prove relevant when examining individuals who consume higher levels of fructose.

Meeting Report: Translational Advances in Cancer Prevention Agent Development Meeting.

The Division of Cancer Prevention of the National Cancer Institute (NCI) and the Office of Disease Prevention of the National Institutes of Health co-sponsored the Translational Advances in Cancer Prevention Agent Development Meeting on August 27 to 28, 2020. The goals of this meeting were to foster the exchange of ideas and stimulate new collaborative interactions among leading cancer prevention researchers from basic and clinical research; highlight new and emerging trends in immunoprevention and chemoprevention as well as new information from clinical trials; and provide information to the extramural research community on the significant resources available from the NCI to promote prevention agent development and rapid translation to clinical trials. The meeting included two plenary talks and five sessions covering the range from pre-clinical studies with chemo/immunopreventive agents to ongoing cancer prevention clinical trials. In addition, two NCI informational sessions describing contract resources for the preclinical agent development and cooperative grants for the Cancer Prevention Clinical Trials Network were also presented.

Translational Advances in Cancer Prevention Agent Development (TACPAD) Virtual Workshop on Immunomodulatory Agents: Report.

The National Cancer Institute (NCI) Division of Cancer Prevention (DCP) convened the "Translational Advances in Cancer Prevention Agent Development (TACPAD) Workshop on Immunomodulatory Agents" as a virtual 2-day workshop on September 13 to 14, 2021. The main goals of this workshop were to foster the exchange of ideas and potentially new collaborative interactions among leading cancer immunoprevention researchers from basic and clinical research and highlight new and emerging trends in immunoprevention. The workshop included an overview of the mechanistic classes of immunomodulatory agents and three sessions covering the gamut from preclinical to clinical studies. The workshop convened individuals working in immunology and cancer prevention to discuss trends in discovery and development of immunomodulatory agents individually and in combination with other chemopreventive agents or vaccines.

Combination of Erlotinib and Naproxen Employing Pulsatile or Intermittent Dosing Profoundly Inhibits Urinary Bladder Cancers.

Daily dosing of either NSAIDs or EGFR inhibitors has been shown to prevent bladder cancer development in a N-butyl-(4-hydroxybutyl)nitrosamine (OH-BBN)-induced rat model. However, these inhibitors cause gastrointestinal ulceration and acneiform rash, respectively, limiting their continuous use in a clinical prevention setting. We studied chemopreventive efficacy of pulsatile dosing of EGFR inhibitor erlotinib (42 mg/kg BW, once/week) combined with intermittent or continuous low doses of the NSAID naproxen (30 mg/kg BW/day, 3 weeks on/off or 128 ppm daily in diet) in the OH-BBN induced rat bladder cancer model. The interventions were started either at 1 or 4 weeks (early intervention) or 3 months (delayed intervention) after the last OH-BBN treatment, by which time the rats had developed microscopic bladder lesions. All combination regimens tested as early versus late intervention led to the reduction of the average bladder tumor weights (54%-82%; P < 0.01 to P < 0.0001), a decrease in tumor multiplicity (65%-85%; P < 0.01 to P < 0.0001), and a decrease in the number of rats with large palpable tumors (>200 mg; 83%-90%; P < 0.01 to P < 0.0001). Levels of signal transduction markers, Ki-67, cyclin D1, IL1ß, pSTAT3, and pERK, were significantly (P < 0.05 to P < 0.001) reduced in the treated tumors, demonstrating their potential utility as predictive markers for efficacy. These findings demonstrate that significant chemopreventive efficacy could be achieved with alternative intervention regimens designed to reduce the toxicity of agents, and that starting erlotinib and/or naproxen treatments at the time microscopic tumors were present still conferred the efficacy.

Intermittent Dosing Regimens of Aspirin and Naproxen Inhibit Azoxymethane-Induced Colon Adenoma Progression to Adenocarcinoma and Invasive Carcinoma.

Chronic use of aspirin and related drugs to reduce cancer risk is limited by unwanted side effects. Thus, we assessed the efficacy associated with different dosing regimens of aspirin and naproxen. Azoxymethane (AOM)-rat colon cancer model was used to establish the pharmacodynamic efficacy of aspirin and naproxen under different dosing regimens. Colon tumors were induced in rats (36/group) by two weekly doses of AOM. At the early adenoma stage, rats were fed diets containing aspirin (700 and 1,400 ppm) or naproxen (200 and 400 ppm), either continuously, 1 week on/1 week off, or 3 weeks on/3 weeks off, or aspirin (2,800 ppm) 3 weeks on/3 weeks off. All rats were euthanized 48 weeks after AOM treatment and assessed for efficacy and biomarkers in tumor tissues. Administration of aspirin and naproxen produced no overt toxicities. Administration of different treatment regimens of both agents had significant inhibitory effects with clear dose-response effects. Aspirin suppressed colon adenocarcinoma multiplicity (both invasive and noninvasive) by 41% (P < 0.003) to 72% (P < 0.0001) and invasive colon adenocarcinomas by 67%-91% (P < 0.0001), depending on the treatment regimen. Naproxen doses of 200 and 400 ppm inhibited invasive adenocarcinoma multiplicity by 53%-88% (P < 0.0001), depending on the dosing regimen. Colonic tumor biomarker analysis revealed that proliferation (proliferating cell nuclear antigen and p21), apoptosis (p53 and Caspase-3), and proinflammatory mediators (IL1ß and prostaglandin E2) were significantly correlated with the tumor inhibitory effects of aspirin and naproxen. Overall, our results suggest that intermittent dosing regimens with aspirin or naproxen demonstrated significant efficacy on the progression of adenomas to adenocarcinomas, without gastrointestinal toxicities.

Pharmacometabolomic Pathway Response of Effective Anticancer Agents on Different Diets in Rats with Induced Mammary Tumors.

Metabolomics is an effective approach to characterize the metabotype which can reflect the influence of genetics, physiological status, and environmental factors such as drug intakes, diet. Diet may change the chemopreventive efficacy of given agents due to the altered physiological status of the subject. Here, metabolomics response to a chemopreventive agent targretin or tamoxifen, in rats with methylnitrosourea-induced tumors on a standard diet (4% fat, CD) or a high fat diet (21% fat, HFD) was evaluated, and found that (1) the metabolome was substantially affected by diet and/or drug treatment; (2) multiple metabolites were identified as potential pharmacodynamic biomarkers related to targretin or tamoxifen regardless of diet and time; and (3) the primary bile acid pathway was significantly affected by targretin treatment in rats on both diets, and the lysolipid pathway was significantly affected by tamoxifen treatment in rats on the high fat diet.

Cancer Chemoprevention: Preclinical In Vivo Alternate Dosing Strategies to Reduce Drug Toxicities.

Cancer chemopreventive agents inhibit the formation of precursor lesions and/or the progression of these lesions to late stage disease. This approach to disease control has the potential to reduce the physical and financial costs of cancer in society. Several drugs that have been approved by the FDA for other diseases and have been extensively evaluated for their safety and pharmacokinetic/pharmacodynamic characteristics have the potential to be repurposed for use as cancer chemopreventive agents. These agents often mechanistically inhibit signaling molecules that play key roles in the carcinogenic process. The safety profile of agents is a primary concern when considering the administration of drugs for chemoprevention, as the drugs will be given chronically to high-risk, asymptomatic individuals. To decrease drug toxicity while retaining efficacy, several approaches are currently being explored. In this short review, we describe studies that use preclinical in vivo models to assess efficacy of alternative drug dosing strategies and routes of drug administration on chemopreventive drug efficacy. In vivo drug dosing strategies that reduce toxicity while retaining efficacy will pave the way for future cancer prevention clinical trials.

Optimized Bexarotene Aerosol Formulation Inhibits Major Subtypes of Lung Cancer in Mice.

Bexarotene has shown inhibition of lung and mammary gland tumorigenesis in preclinical models and in clinical trials. The main side effects of orally administered bexarotene are hypertriglyceridemia and hypercholesterolemia. We previously demonstrated that aerosolized bexarotene administered by nasal inhalation has potent chemopreventive activity in a lung adenoma preclinical model without causing hypertriglyceridemia. To facilitate its future clinical translation, we modified the formula of the aerosolized bexarotene with a clinically relevant solvent system. This optimized aerosolized bexarotene formulation was tested against lung squamous cell carcinoma mouse model and lung adenocarcinoma mouse model and showed significant chemopreventive effect. This new formula did not cause visible signs of toxicity and did not increase plasma triglycerides or cholesterol. This aerosolized bexarotene was evenly distributed to the mouse lung parenchyma, and it modulated the microenvironment in vivo by increasing the tumor-infiltrating T cell population. RNA sequencing of the lung cancer cell lines demonstrated that multiple pathways are altered by bexarotene. For the first time, these studies demonstrate a new, clinically relevant aerosolized bexarotene formulation that exhibits preventive efficacy against the major subtypes of lung cancer. This approach could be a major advancement in lung cancer prevention for high risk populations, including former and present smokers.

Comparison of Effects of Diet on Mammary Cancer: Efficacy of Various Preventive Agents and Metabolomic Changes of Different Diets and Agents.

To determine the effects of diet, rats were placed on a standard diet (4% fat) or on a modified Western (high-fat diet, HFD) diet (21% fat) at 43 days of age (DOA) and administered methylnitrosourea (MNU) at 50 DOA. Rats were administered effective (tamoxifen, vorozole, and Targretin) or ineffective (metformin and Lipitor) chemopreventive agents either by daily gavage or in the diet beginning at 57 DOA and continuing until sacrifice (190 DOA). Latency period of the tumors was determined by palpation, and multiplicity and cancer weights per rat were determined at final sacrifice. Rats on the HFD versus standard diet had: (i) a 6% increase in final body weights; (ii) significant decreases in tumor latency; and (iii) significant increases in final tumor multiplicity and average tumor weight. Tamoxifen, vorozole, and Targretin were highly effective preventive agents, whereas Lipitor and metformin were ineffective in rats on either diet. Serum was collected at 78 DOA and at sacrifice (190 DOA), and metabolomics were determined to identify the metabolite changes due to diets and effective agents. Rats given the HFD had increased levels of saturated free fatty acids (including myristate) and decreased levels of 2-aminooctanoate. Furthermore, rats on the HFD diet had increased levels of 2-aminobutyrate and decreases in glycine markers previously identified as indicators of prediabetes. Targretin increased long-chain glycophospholipids (e.g., oleyl-linoleoyl-glycerophosphocholine) and decreased primary bile acids (e.g., taurocholate). Tamoxifen increased palmitoyl-linoleoyl-glycophosphocholine and decreased stearoyl-arachidonyl glycophosphocholine. Finally, increased levels of methylated nucleotides (5-methylcytidine) and decreased levels of urea cycle metabolites (N-acetylcitrulline) were associated with the presence of mammary cancers.

Airway brushing as a new experimental methodology to detect airway gene expression signatures in mouse lung squamous cell carcinoma.

As a consequence of exposure to environmental toxicants, a "field cancerization" effect occurs in the lung, resulting in the development of a field of initiated, but morphologically normal appearing cells within a damaged epithelium containing mutations in oncogene or tumor suppressor genes. Unlike humans, whose airway field of injury associated with lung cancer has long been investigated with airway brushings obtained via bronchoscopy, no methods are available for similar studies in the mouse due to the small size of the murine airways. In this protocol, we describe a detailed method for performing airway brushing from a live mouse, which enables repeated sampling from the same mouse and thus, mimicking the bronchoscopy protocol used in humans. Using this approach in the N-nitroso-tris-chloroethylurea (NTCU)-induced mouse lung squamous cell carcinoma (SCC) model, we isolated airway epithelial cells with intact cell membrane structure and then performed transcriptome sequencing (RNA-Seq). We found activation of the PI3K signaling network to be the most significant in cytologically normal bronchial airway epithelial cells of mice with preneoplastic lung SCC lesions. Prolonged exposure to NTCU also induced activation of NF-kappaB (NFƙB), the downstream pathway of PI3K; this NTCU-induced lung SCC progression can be reversed by blocking the NFƙB pathway.

Release of MicroRNAs into Body Fluids from Ten Organs of Mice Exposed to Cigarette Smoke.

Purpose: MicroRNAs are small non-coding RNAs that regulate gene expression, thereby playing a role in a variety of physiological and pathophysiological states. Exposure to cigarette smoke extensively downregulates microRNA expression in pulmonary cells of mice, rats, and humans. Cellular microRNAs are released into body fluids, but a poor parallelism was previously observed between lung microRNAs and circulating microRNAs. The purpose of the present study was to validate the application of this epigenetic biomarker by using less invasive collection procedures. Experimental design: Using microarray analyses, we measured 1135 microRNAs in 10 organs and 3 body fluids of mice that were either unexposed or exposed to mainstream cigarette smoke for up to 8 weeks. The results obtained with selected miRNAs were validated by qPCR. Results: The lung was the main target affected by smoke (190 dysregulated miRNAs), followed by skeletal muscle (180), liver (138), blood serum (109), kidney (96), spleen (89), stomach (36), heart (33), bronchoalveolar lavage fluid (32), urine (27), urinary bladder (12), colon (5), and brain (0). Skeletal muscle, kidney, and lung were the most important sources of smoke-altered microRNAs in blood serum, urine, and bronchoalveolar lavage fluid, respectively. Conclusions: microRNA expression analysis was able to identify target organs after just 8 weeks of exposure to smoke, well before the occurrence of any detectable histopathological alteration. The present translational study validates the use of body fluid microRNAs as biomarkers applicable to human biomonitoring for mechanistic studies, diagnostic purposes, preventive medicine, and therapeutic strategies.

Early and late effects of aspirin and naproxen on microRNAs in the lung and blood of mice, either unexposed or exposed to cigarette smoke.

We recently showed that nonsteroidal anti-inflammatory drugs (NSAIDs) are able to inhibit the lung tumors induced by cigarette smoke, either mainstream (MCS) or environmental (ECS), in female mice. We used subsets of mice to analyze the expression of 1135 microRNAs in both lung and blood serum, as related to the whole-body exposure to smoke and/or oral administration of either aspirin or naproxen. In a first study, we evaluated early microRNA alterations in A/J mice exposed to ECS for 10 weeks, starting at birth, and/or treated with NSAIDs for 6 weeks, starting after weaning. At that time, when no histopathological change were apparent, ECS caused a considerable downregulation of pulmonary microRNAs affecting both adaptive mechanisms and disease-related pathways. Aspirin and naproxen modulated, with intergender differences, the expression of microRNAs having a variety of functions, also including regulation of cyclooxygenases and inflammation. In a second study, we evaluated late microRNA alterations in Swiss H mice exposed to MCS during the first 4 months of life and treated with NSAIDs after weaning until 7.5 months of life, when tumors were detected in mouse lung. Modulation of pulmonary microRNAs by the two NSAIDs was correlated with their ability to prevent preneoplastic lesions (microadenomas) and adenomas in the lung. In both studies, exposure to smoke and/or treatment with NSAIDs also modulated microRNA profiles in the blood serum. However, their levels were poorly correlated with those of pulmonary microRNAs, presumably because circulating microRNAs reflect the contributions from multiple organs and not only from lung.

Effect of weekly or daily dosing regimen of Gefitinib in mouse models of lung cancer.

Gefitinib showed response in phase II clinical trials and with better clinical response in lung cancer with activating mutations in the tyrosine kinase domain of the EGFR. Questions of toxicity and potential dosing regimens impede the use in a prevention setting. This study will provide scientific evidence for the utility of testing and comparing weekly and daily dosing regimens in clinical trials. We employed the adenocarcinoma (AD) and squamous cell carcinoma (SCC) models to compare the efficacy of Gefitinib in daily or weekly dosing regimens. We also assessed the effectiveness of Gefitinib in altering growth of the H3255 xenograft. Bioluminescent imaging (BLI) and tumor size was evaluated. Relative expression of phospho-EGFR, phospho-ERK and phospho-AKT in the xenograft were evaluated by Western Blot analysis. In the lung AD model, Gefitinib showed significant inhibition of tumor load when treated with weekly or weekly intermittent dosing regimens in AJ/p53 val135/wt mice whereas a daily dosing regimen did not decrease the tumor load significantly. In the H3255-Luciferase xenograft model, weekly treatment demonstrated better inhibition than daily treatment. The weekly dosing regimen exhibited greater inhibition of phospho-EGFR, phospho-ERK and phospho-AKT than the daily dosing regimen, which may be correlated with the antitumor effects of the different dosing regimens. Weekly dosing with Gefitinib had similar or better efficacy than the daily dosing regimen in pre-clinical models of NSCLC. The data provide scientific evidences for the utility of testing and comparing weekly and intermittent dosing regimens in clinical trials.

Pioglitazone-mediated reversal of elevated glucose metabolism in the airway epithelium of mouse lung adenocarcinomas.

Airway epithelial cells are prone to the damage caused by lung cancer risk factors, such as cigarette smoking. Little is known about surrogate biomarkers in the bronchial airway epithelium that can be used to assess the effect of potential chemoprevention drugs on lung adenocarcinoma formation/progression. Pioglitazone has been suggested as a chemoprevention drug for lung cancer. To study the mechanisms underlying the role of pioglitazone in lung cancer prevention, we performed transcriptome sequencing (RNA-Seq) and found that Kras signaling was repressed by pioglitazone treatment in the airway epithelial cells of mice with lung adenocarcinoma (FDR q = 9.8E-04). It was also found that glucose metabolic pathways were elevated in the airway epithelium of mice with lung adenocarcinomas and inhibited by pioglitazone treatment (FDR q = 0.01). Downregulation of glucose metabolism genes was also observed in lung tumors of mice treated with pioglitazone. The high-risk expression signature of elevated glucose metabolism was associated with poor survival outcome in multiple lung adenocarcinoma patient populations (P values ranging from 1.0E-9 to 5.5E-5). Our results suggest that the role of pioglitazone in preventing lung adenocarcinoma may depend on inhibiting Kras signaling and glucose metabolism, which may serve as biomarkers of agent action in the airway epithelium.

Fixed-Dose Combinations of Pioglitazone and Metformin for Lung Cancer Prevention.

Combination treatment with pioglitazone and metformin is utilized clinically in the treatment of type II diabetes. Treatment with this drug combination reduced the development of aerodigestive cancers in this patient population. Our goal is to expand this treatment into clinical lung cancer chemoprevention. We hypothesized that dietary delivery of metformin/pioglitazone would prevent lung adenoma formation in A/J mice in a benzo[a]pyrene (B[a]P)-induced carcinogenesis model while modulating chemoprevention and anti-inflammatory biomarkers in residual adenomas. We found that metformin (500 and 850 mg/kg/d) and pioglitazone (15 mg/kg/d) produced statistically significant decreases in lung adenoma formation both as single-agent treatments and in combination, compared with untreated controls, after 15 weeks. Treatment with metformin alone and in combination with pioglitazone resulted in statistically significant decreases in lung adenoma formation at both early- and late-stage interventions. Pioglitazone alone resulted in significant decreases in adenoma formation only at early treatment intervention. We conclude that oral metformin is a viable chemopreventive treatment at doses ranging from 500 to 1,000 mg/kg/d. Pioglitazone at 15 mg/kg/d is a viable chemopreventive agent at early-stage interventions. Combination metformin and pioglitazone performed equal to metformin alone and better than pioglitazone at 15 mg/kg/d. Because the drugs are already FDA-approved, rapid movement to human clinical studies is possible. Cancer Prev Res; 10(2); 116-23. ©2017 AACR.