Role of ATP-binding cassette transporters in cancer initiation and progression.

ATP Binding Cassette (ABC) transporters, widely studied in cancer for their role in drug resistance, have been more recently also considered for their contribution to cancer cell biology. To date, many data provide evidences for their potential role in all the phases of cancer development from cancer susceptibility, tumor initiation, tumor progression and metastasis. Although many evidences are based on correlative analyses, data describing a direct or indirect role of ABC transporters in cancer biology are increasing. Overall, current available information suggests a relevant molecular effector role of some ABC transporters in cancer invasion and metastasis as reported in experimental tumor models. From a therapeutic point of view, due to the physiological relevant roles that ABC transporters play in the organism, the capability to selectively inhibit the function or the expression of ABC transporters in cancer stem cells or other tumor cells, represents the main challenge for researcher scientists. A detailed and updated description of the current knowledge on the role of ABC transporters in cancer biology is provided.

Focus on Biochemical and Clinical Predictors of Response to Immune Checkpoint Inhibitors in Metastatic Urothelial Carcinoma: Where Do We Stand?

Urothelial bladder cancer is one of the most lethal cancers worldwide with barely 5% five-year survival in patients with metastatic disease. Intravesical immunotherapy with Bacillus Calmette-Guérin and platinum-based chemotherapy are currently the standard of care for non-muscle invasive and advanced or metastatic urothelial cancer (mUC), respectively. Recently, a subset of patients with locally advanced or mUC has shown to be responsive to immune checkpoint inhibitors (ICIs), e.g., the anti-cytotoxic T-lymphocyte-associated protein 4 and programmed cell death -1/programmed death-ligand1 (PD-1/PD-L1) antibodies. Due to the relevant clinical benefit of immunotherapy for mUC, in 2016, the United States Food and Drug Administration (FDA) approved five immunotherapeutic agents as second-line or first-line treatments for patients with advanced bladder cancer who did not profit from or were ineligible for standard therapy. In this review, we discuss the role of immunotherapy in bladder cancer and recent clinical applications of PD-1/PD-L1 blockade in mUC. Furthermore, we evaluate a variable response rate to ICIs treatment and outline potential biomarkers predictive of immunotherapy response.

Immune Checkpoint Inhibitors in Pre-Treated Gastric Cancer Patients: Results from a Literature-Based Meta-Analysis.

Immunotherapy has recently changed the treatment of several cancers. We performed a literature-based meta-analysis of randomised controlled trials to assess the efficacy of the novel immune checkpoint inhibitors (ICIs) in metastatic gastric cancer. The main outcome was overall survival. Based on age (cut-off agreed at 65 years), tumour location (gastric vs. gastro-oesophageal junction), programmed death-ligand 1 (PD-L1) status, sex and Eastern Cooperative Oncology Group (ECOG) status (1 vs. 0), we scheduled a subgroup analysis for the overall survival. Three studies were included in the analysis for a total of 1456 cases (811 cases were in the experimental group and 645 cases in the control group). The pooled analysis showed improved overall survival in the experimental arm in the absence of statistical significance (hazard ratio (HR) = 0.87, 95% CI: 0.64-1.18; p = 0.37). The subgroup of patients with PD-L1-positive tumours (HR = 0.82 vs. 1.04) and gastro-oesophageal junction cancer (HR = 0.82 vs. 1.04) showed a statistically significant advantage of overall survival. This study supports the efficacy of immune checkpoint inhibitors in the subgroup of patients with metastatic gastric cancer with PD-L1-positive and gastro-oesophageal junction tumour location. Future studies are needed with the aim of identifying reliable predictive biomarkers of ICI efficacy.

RNA sequencing reveals PNN and KCNQ1OT1 as predictive biomarkers of clinical outcome in stage III colorectal cancer patients treated with adjuvant chemotherapy.

Five-year overall survival of stage III colorectal cancer (CRC) patients treated with standard adjuvant chemotherapy (ACHT) is highly variable. Genomic biomarkers and/or transcriptomic profiles identified lack of adequate validation. Aim of our study was to identify and validate molecular biomarkers predictive of ACHT response in stage III CRC patients by a transcriptomic approach. From a series of CRC patients who received ACHT, two stage III extreme cohorts (unfavorable vs. favorable prognosis) were selected. RNA-sequencing was performed from fresh frozen explants. Tumors were characterized for somatic mutations. Validation was performed in stage III CRC patients extracted from two GEO datasets. According to disease-free survival (DFS), 108 differentially expressed genes (104/4 up/downregulated in the unfavorable prognosis group) were identified. Among 104 upregulated genes, 42 belonged to olfactory signaling pathways, 62 were classified as pseudogenes (n = 17), uncharacterized noncoding RNA (n = 10), immune response genes (n = 4), microRNA (n = 1), cancer-related genes (n = 14) and cancer-unrelated genes (n = 16). Three out of four down-regulated genes were cancer-related. Mutational status (i.e., RAS, BRAF, PIK3CA) did not differ among the cohorts. In the validation cohort, multivariate analysis showed high PNN and KCNQ1OT1 expression predictive of shorter DFS in ACHT treated patients (p = 0.018 and p = 0.014, respectively); no difference was observed in untreated patients. This is the first study that identifies by a transcriptomic approach and validates PNN and KCNQ1OT1 as molecular biomarkers predictive of chemotherapy response in stage III CRC patients. After a further validation in an independent cohort, PNN and KCNQ1OT1 evaluation could be proposed to prospectively identify stage III CRC patients benefiting from ACHT.

A case report of eyelid Merkel cell carcinoma occurring under treatment with nivolumab for a lung adenocarcinoma.

BACKGROUND: Merkel cell carcinoma (MCC) is a rare neuroendocrine malignancy of the skin characterized by high aggressiveness. Four main factors are implicated in its development: immunosuppression, ultraviolet radiation, age and the Merkel cell polyomavirus (MCPyV). In recent years, immune checkpoint inhibitors have shown clinical activity in MCC treatment. CASE PRESENTATION: We report the case of an 82-year-old man with a lung adenocarcinoma diagnosis, who underwent immunotherapy with nivolumab as second-line treatment. Seven months after the diagnosis of lung cancer during the nivolumab treatment, the patient developed an eyelid MCC, initially misdiagnosed as a chalazion. A palliative radiotherapy was performed with clinical benefit. After a total of seven cycles of nivolumab, computed tomography showed a lung and cerebral disease progression. In addition, clinical conditions worsened leading to the patient's death 13 months after the initial lung cancer diagnosis. CONCLUSIONS: Cases of co-occurrence of MCC and non-small cell lung cancer (NSCLC) have rarely been reported. Interestingly, common risk factors may be postulated for both cancers. Considering the rarity of this adverse event, its short-term temporal relation with the administration of the drug, which makes a relation improbable, and the coexistence of other risk factors, which may provide plausible explanations, it is possible to conclude according to the WHO Adverse Reaction Terminology that a causal relation between the occurrence of this serious adverse event and the exposure to the drug is unlikely. However, the case deserves to be reported in the literature.

Clinical validity of a DPYD-based pharmacogenetic test to predict severe toxicity to fluoropyrimidines.

Pre-therapeutic DPYD pharmacogenetic test to prevent fluoropyrimidines (FL)-related toxicities is not yet common practice in medical oncology. We aimed at investigating the clinical validity of DPYD genetic analysis in a large series of oncological patients. Six hundred three cancer patients, treated with FL, have been retrospectively tested for eight DPYD polymorphisms (DPYD-rs3918290, DPYD-rs55886062, DPYD-rs67376798, DPYD-rs2297595, DPYD-rs1801160, DPYD-rs1801158, DPYD-rs1801159, DPYD-rs17376848) for association with Grade ≥3 toxicity, developed within the first three cycles of therapy. DPYD-rs3918290 and DPYD-rs67376798 were associated to Grade ≥3 toxicity after bootstrap validation and Bonferroni correction (p = 0.003, p = 0.048). DPYD-rs55886062 was not significant likely due to its low allelic frequency, nonetheless one out of two heterozygous patients (compound heterozygous with DPYD-rs3918290) died from toxicity after one cycle. Test specificity for the analysis of DPYD-rs3918290, DPYD-rs55886062 and DPYD-rs67376798 was assessed to 99%. Among the seven patients carrying one variant DPYD-rs3918290, DPYD-rs55886062 or DPYD-rs67376798 allele, not developing Grade ≥3 toxicity, 57% needed a FL dose or schedule modification for moderate chronic toxicity. No other DPYD polymorphism was associated with Grade ≥3 toxicity. Our data demonstrate the clinical validity and specificity of the DPYD-rs3918290, DPYD-rs55886062, DPYD-rs67376798 genotyping test to prevent FL-related Grade ≥3 toxicity and to preserve treatment compliance, and support its introduction in the clinical practice.

Chemistry and biology of two novel gold(I) carbene complexes as prospective anticancer agents.

Two novel gold carbene compounds, namely, chlorido (1-butyl-3-methyl-imidazole-2-ylidene) gold(I) (1) and bis(1-butyl-3-methyl-imidazole-2-ylidene) gold(I) (2), were prepared and characterized as prospective anticancer drug candidates. These compounds consist of a gold(I) center linearly coordinated either to one N-heterocyclic carbene (NHC) and one chloride ligand (1) or to two identical NHC ligands (2). Crystal structures were solved for both compounds, the resulting structural data being in good agreement with expectations. We wondered whether the presence of two tight carbene ligands in 2 might lead to biological properties distinct from those of the monocarbene complex 1. Notably, in spite of their appreciable structural differences, these two compounds manifested similarly potent cytotoxic actions in vitro when challenged against A2780 human ovarian carcinoma cells. In addition, both were able to overcome resistance to cisplatin in the A2780R line. Solution studies revealed that these gold carbene complexes are highly stable in aqueous buffers at physiological pH. Their reactivity with proteins was explored: no adduct formation was detected even upon a long incubation with the model proteins cytochrome c and lysozyme; in contrast, both compounds were able to metalate, to a large extent, the copper chaperone Atox-1, bearing a characteristic CXXC motif. The precise nature of the resulting gold-Atox-1 adducts was elucidated through ESI-MS analysis. On the basis of these findings, it is proposed that the investigated gold(I) carbene compounds are promising antiproliferative agents warranting a wider pharmacological evaluation. Most likely these gold compounds produce their potent biological effects through selective metalation and impairment of a few crucial cellular proteins.

In vitro assessment of antibody-conjugated gold nanorods for systemic injections.

BACKGROUND: The interest for gold nanorods in biomedical optics is driven by their intense absorbance of near infrared light, their biocompatibility and their potential to reach tumors after systemic administration. Examples of applications include the photoacoustic imaging and the photothermal ablation of cancer. In spite of great current efforts, the selective delivery of gold nanorods to tumors through the bloodstream remains a formidable challenge. Their bio-conjugation with targeting units, and in particular with antibodies, is perceived as a hopeful solution, but the complexity of living organisms complicates the identification of possible obstacles along the way to tumors. RESULTS: Here, we present a new model of gold nanorods conjugated with anti-cancer antigen 125 (CA125) antibodies, which exhibit high specificity for ovarian cancer cells. We implement a battery of tests in vitro, in order to simulate major nuisances and predict the feasibility of these particles for intravenous injections. We show that parameters like the competition of free CA125 in the bloodstream, which could saturate the probe before arriving at the tumors, the matrix effect and the interference with erythrocytes and phagocytes are uncritical. CONCLUSIONS: Although some deterioration is detectable, anti-CA125-conjugated gold nanorods retain their functional features after interaction with blood tissue and so represent a powerful candidate to hit ovarian cancer cells.

Ultramicronized N-palmitoylethanolamine associated with analgesics: Effects against persistent pain.

Current epidemiological data estimate that one in five people suffers from chronic pain with considerable impairment of health-related quality of life. The pharmacological treatment is based on first- and second-line analgesic drugs, including COX-2 selective and nonselective nonsteroidal anti-inflammatory drugs, paracetamol, antidepressants, anti-seizure drugs and opioids, that are characterized by important side effects. N-palmitoylethanolamine (PEA) is a body's own fatty-acid ethanolamide belonging to the family of autacoid local injury antagonist amides. The anti-inflammatory and pain-relieving properties of PEA have been recognized for decades and prompted to depict its role in the endogenous mechanisms of pain control. Together with its relative abundance in food sources, this opened the way to the use of PEA as a pain-relieving nutritional intervention. Naïve PEA is a large particle size lipid molecule with low solubility and bioavailability. Reducing particle size is a useful method to increase surface area, thereby improving dissolution rate and bioavailability accordingly. Micron-size formulations of PEA (e.g., ultramicronized and co-(ultra)micronized) have shown higher oral efficacy compared to naïve PEA. In particular, ultramicronized PEA has been shown to efficiently cross the intestinal wall and, more importantly, the blood-brain and blood-spinal cord barrier. Several preclinical and clinical studies have shown the efficacy, safety and tolerability of ultramicronized PEA. This narrative review summarizes the available pharmacokinetic/pharmacodynamic data on ultramicronized PEA and focuses to its contribution to pain control, in particular as 'add-on' nutritional intervention. Data showing the ability of ultramicronized PEA to limit opioid side effects, including the development of tolerance, have also been reviewed.

Platinum-based chemotherapy in metastatic prostate cancer: what possibilities?

Metastatic prostate cancer is a major health burden worldwide, necessitating the continuous development of effective treatment strategies. Androgen deprivation therapy remains the cornerstone of prostate cancer treatment, but novel approaches are needed for metastatic castration-resistant prostate cancer (mCRPC). Recent studies have highlighted the prevalence of mutations in DNA repair genes, including BRCA1 and BRCA2, in mCRPC patients, rendering them more susceptible to platinum-based chemotherapy and Poly (ADP-ribose) polymerase (PARP) inhibitors. Platinum-based chemotherapy, particularly in combination with taxanes, has demonstrated encouraging activity in mCRPC, as well as homologous recombination gene alterations have shown increased sensitivity to platinum compounds in these patients. The combination of platinum-based chemotherapy with PARP inhibitors represents a novel and potentially effective therapeutic strategy for this subgroup of patients. However, the optimal sequence of administering these agents and the potential for cross-resistance and cross-toxicities remain areas requiring further investigation. Prospective randomized studies are essential to elucidate the most effective treatment approach for this challenging patient population. This review aims to explore the potential of platinum-based chemotherapy in the context of prostate cancer, and more in detail in homologous recombination repair (HRR) mutated patients. We discuss the synergistic effects of combining platinum compounds with PARP inhibitors and the potential benefits of adopting specific therapeutic sequences.

Ultramicronized N-palmitoylethanolamine Contributes to Morphine Efficacy Against Neuropathic Pain: Implication of Mast Cells and Glia.

BACKGROUND: In the current management of neuropathic pain, in addition to antidepressants and anticonvulsants, the use of opioids is wide, despite their related and well-known issues. OBJECTIVE: N-palmitoylethanolamine (PEA), a natural fatty-acid ethanolamide whose anti-inflammatory, neuroprotective, immune-modulating and anti-hyperalgesic activities are known, represents a promising candidate to modulate and/or potentiate the action of opioids. METHODS: This study was designed to evaluate if the preemptive and morphine concomitant administration of ultramicronized PEA, according to fixed or increasing doses of both compounds, delays the onset of morphine tolerance and improves its analgesic efficacy in the chronic constriction injury (CCI) model of neuropathic pain in rats. RESULTS: Behavioral experiments showed that the preemptive and co-administration of ultramicronized PEA significantly decreased the effective dose of morphine and delayed the onset of morphine tolerance. The activation of spinal microglia and astrocytes, commonly occurring both on opioid treatment and neuropathic pain, was investigated through GFAP and Iba-1 immunofluorescence. Both biomarkers were found to be increased in CCI untreated or morphine treated animals in a PEA-sensitive manner. The increased density of endoneural mast cells within the sciatic nerve of morphine-treated and untreated CCI rats was significantly reduced by ultramicronized PEA. The decrease of mast cell degranulation, evaluated in terms of reduced plasma levels of histamine and N-methyl-histamine metabolite, was mainly observed at intermediate-high doses of ultramicronized PEA, with or without morphine. CONCLUSION: Overall, these results show that the administration of ultramicronized PEA in CCI rats according to the study design fully fulfilled the hypotheses of this study.

Optimizing aspirin dose for colorectal cancer patients through deep phenotyping using novel biomarkers of drug action.

Background: Low-dose aspirin's mechanism of action for preventing colorectal cancer (CRC) is still debated, and the optimal dose remains uncertain. We aimed to optimize the aspirin dose for cancer prevention in CRC patients through deep phenotyping using innovative biomarkers for aspirin's action. Methods: We conducted a Phase II, open-label clinical trial in 34 CRC patients of both sexes randomized to receive enteric-coated aspirin 100 mg/d, 100 mg/BID, or 300 mg/d for 3 ± 1 weeks. Biomarkers were evaluated in blood, urine, and colorectal biopsies at baseline and after dosing with aspirin. Novel biomarkers of aspirin action were assessed in platelets and colorectal tissues using liquid chromatography-mass spectrometry to quantify the extent of cyclooxygenase (COX)-1 and COX-2 acetylation at Serine 529 and Serine 516, respectively. Results: All aspirin doses caused comparable % acetylation of platelet COX-1 at Serine 529 associated with similar profound inhibition of platelet-dependent thromboxane (TX)A2 generation ex vivo (serum TXB2) and in vivo (urinary TXM). TXB2 was significantly reduced in CRC tissue by aspirin 300 mg/d and 100 mg/BID, associated with comparable % acetylation of COX-1. Differently, 100 mg/day showed a lower % acetylation of COX-1 in CRC tissue and no significant reduction of TXB2. Prostaglandin (PG)E2 biosynthesis in colorectal tumors and in vivo (urinary PGEM) remained unaffected by any dose of aspirin associated with the variable and low extent of COX-2 acetylation at Serine 516 in tumor tissue. Increased expression of tumor-promoting genes like VIM (vimentin) and TWIST1 (Twist Family BHLH Transcription Factor 1) vs. baseline was detected with 100 mg/d of aspirin but not with the other two higher doses. Conclusion: In CRC patients, aspirin 300 mg/d or 100 mg/BID had comparable antiplatelet effects to aspirin 100 mg/d, indicating similar inhibition of the platelet's contribution to cancer. However, aspirin 300 mg/d and 100 mg/BID can have additional anticancer effects by inhibiting cancerous tissue's TXA2 biosynthesis associated with a restraining impact on tumor-promoting gene expression. EUDRACT number: 2018-002101-65. Clinical Trial Registration: ClinicalTrials.gov, identifier NCT03957902.

Validation of single nucleotide polymorphisms potentially related to R-CHOP resistance in diffuse large B-cell lymphoma patients.

Aim: Diffuse large B-cell lymphoma (DLBCL) is the most common B-cell non-Hodgkin lymphoma (NHL). Despite the availability of clinical and molecular algorithms applied for the prediction of prognosis, in up to 30%-40% of patients, intrinsic or acquired drug resistance occurs. Constitutional genetics may help to predict R-CHOP resistance. This study aimed to validate previously identified single nucleotide polymorphisms (SNPs) in the literature as potential predictors of R-CHOP resistance in DLBCL patients, SNPs. Methods: Twenty SNPs, involved in R-CHOP pharmacokinetics/pharmacodynamics or other pathobiological processes, were investigated in 185 stage I-IV DLBCL patients included in a multi-institution pharmacogenetic study to validate their previously identified correlations with resistance to R-CHOP. Results: Correlations between rs2010963 (VEGFA gene) and sex (P = 0.046), and rs1625895 (TP53 gene) and stage (P = 0.003) were shown. After multivariate analyses, a concordant effect (i.e., increased risk of disease progression and death) was observed for rs1883112 (NCF4 gene) and rs1800871 (IL10 gene). When patients were grouped according to the revised International Prognostic Index (R-IPI), both these SNPs further discriminated progression-free survival (PFS) and overall survival (OS) of the R-IPI-1-2 subgroup. Overall, patients harboring the rare allele showed shorter PFS and OS compared with wild-type patients. Conclusions: Two out of the 20 study SNPs were validated. Thus, these results support the role of previously identified rs1883112 and rs1800871 in predicting DLBCL resistance to R-CHOP and highlight their ability to further discriminate the prognosis of R-IPI-1-2 patients. These data point to the need to also focus on host genetics for a more comprehensive assessment of DLBCL patient outcomes in future prospective trials.

Immunotherapy-related biomarkers: Confirmations and uncertainties.

Immunotherapy profoundly changed oncology treatment, becoming one of the main therapeutical strategies. Remarkable improvement has been achieved in survival outcomes, but the percentage of patients who benefit from immunotherapy is still limited. Only one-third of patients receiving immune checkpoint inhibitors (ICIs) achieve long-term response. Several patients are not responsive to treatment or relapse after an initial response. To date, programmed death-ligand 1, microsatellite instability, and tumor mutational burden are the three biomarkers validated to predict the ICIs response, but a single variable seems still insufficient in the patient's selection. Considering the substantial and increasing use of these drugs, the identification of new predictive biomarkers of ICI response is of paramount importance. We summarize the state of the art and the clinical use of immune biomarkers in oncology, highlighting the strength and weaknesses of currently approved biomarkers, describing the emerging tissues and circulating biomarkers, and outlining future perspectives.

Principles of Molecular Utility for CMS Classification in Colorectal Cancer Management.

Colorectal cancer (CRC) is the second cause of cancer-related deaths in both sexes globally and presents different clinical outcomes that are described by a range of genomic and epigenomic alterations. Despite the advancements in CRC screening plans and treatment strategies, the prognosis of CRC is dismal. In the last two decades, molecular biomarkers predictive of prognosis have been identified in CRC, although biomarkers predictive of treatment response are only available for specific biological drugs used in stage IV CRC. Translational clinical trials mainly based on "omic" strategies allowed a better understanding of the biological heterogeneity of CRCs. These studies were able to classify CRCs into subtypes mainly related to prognosis, recurrence risk, and, to some extent, also to treatment response. Accordingly, the comprehensive molecular characterizations of CRCs, including The Cancer Genome Atlas (TCGA) and consensus molecular subtype (CMS) classifications, were presented to improve the comprehension of the genomic and epigenomic landscapes of CRCs for a better patient management. The CMS classification obtained by the CRC subtyping consortium categorizes CRC into four consensus molecular subtypes (CMS1-4) characterized by different prognoses. In this review, we discussed the CMS classification in different settings with a focus on its relationships with precursor lesions, tumor immunophenotype, and gut microbiota, as well as on its role in predicting prognosis and/or response to pharmacological treatments, as a crucial step towards precision medicine.

Exploratory Genome-Wide Association Analysis to Identify Pharmacogenetic Determinants of Response to R-CHOP in Diffuse Large B-Cell Lymphoma.

R-CHOP standard chemotherapy is successful in about 60% of diffuse large B-cell lymphoma (DLBCL) patients. Unresponsive patients have a poor prognosis, and predictive biomarkers of response to R-CHOP are lacking. We conducted the first prospective GWAS study aimed at exploring constitutional biomarkers predictive of R-CHOP efficacy and toxicity. Overall, 216 any-stage chemonaïve DLBCL patients candidate to R-CHOP were enrolled. The median age of the 185 eligible patients was 59.2 years, 49.7% were women and 45.4% were stage I-II patients. According to the Revised International Prognostic Index (R-IPI), 14.1%, 56.8% and 29.2% were in the very good, good and poor prognosis groups, respectively. Of the patients, 85.9% produced a complete response. Highly significant associations (i.e., p < 5 × 10-8) were found between progression-free survival (PFS) and six SNPs (i.e., rs116665727, rs1607795, rs75614943, rs77241831, rs117500207, rs78466241). Additionally, five SNPs (i.e., rs74832512, rs117500207, rs35789195, rs11721010, rs12356569) were highly associated with overall survival (OS). Wild-type patients showed a prolonged PFS or OS compared with patients carrying deleterious alleles (p < 0.001). No association with the adequate significant threshold was observed between SNPs and the objective response or toxicity. In the future, these SNPs, alone or in combination, after a proper validation in an independent cohort, could contribute to improving the prediction of R-CHOP response.

Overcoming tumor multidrug resistance using drugs able to evade P-glycoprotein or to exploit its expression.

Multidrug resistance (MDR) is a major obstacle to the effective treatment of cancer. Cellular overproduction of P-glycoprotein (P-gp), which acts as an efflux pump for various anticancer drugs (e.g. anthracyclines, Vinca alkaloids, taxanes, epipodophyllotoxins, and some of the newer antitumor drugs) is one of the more relevant mechanisms underlying MDR. P-gp belongs to the superfamily of ATP-binding cassette transporters and is encoded by the ABCB1 gene. Its overexpression in cancer cells has become a therapeutic target for circumventing MDR. As an alternative to the classical pharmacological strategy of the coadministration of pump inhibitors and cytotoxic substrates of P-gp and to other approaches applied in experimental tumor models (e.g. P-gp-targeting antibodies, ABCB1 gene silencing strategies, and transcriptional modulators) and in the clinical setting (e.g. incapsulation of P-gp substrate anticancer drugs into liposomes or nanoparticles), a more intriguing strategy for circumventing MDR is represented by the development of new anticancer drugs which are not substrates of P-gp (e.g. epothilones, second- and third-generation taxanes and other microtubule modulators, topoisomerase inhibitors). Some of these drugs have already been tested in clinical trials and, in most of cases, show relevant activity in patients previously treated with anticancer agents which are substrates of P-gp. Of these drugs, ixabepilone, an epothilone, was approved in the United States for the treatment of breast cancer patients pretreated with an anthracycline and a taxane. Another innovative approach is the use of molecules whose activity takes advantage of the overexpression of P-gp. The possibility of overcoming MDR using the latter two approaches is reviewed herein.

Synthesis, structural characterization, solution behavior, and in vitro antiproliferative properties of a series of gold complexes with 2-(2'-pyridyl)benzimidazole as ligand: comparisons of gold(III) versus gold(I) and mononuclear versus binuclear derivatives.

A variety of gold(III) and gold(I) derivatives of 2-(2'-pyridyl)benzimidazole (pbiH) were synthesized and fully characterized and their antiproliferative properties evaluated in a representative ovarian cancer cell line. The complexes include the mononuclear species [(pbi)AuX(2)] (X = Cl, 1; OAc, 2), [(pbiH)AuCl] (3), [(pbiH)Au(PPh(3))][PF(6)] (4-PF(6)), and [(pbi)Au(L)] (L = PPh(3), 5; TPA, 6), and the binuclear gold(I)/gold(I) and gold(I)/gold(III) derivatives [(PPh(3))(2)Au(2)(µ(2)-pbi)][PF(6)] (10-PF(6)), [ClAu(µ(3)-pbi)AuCl(2)] (7),and [(PPh(3))Au(µ(3)-pbi)AuX(2)][PF(6)] (X = Cl, 8-PF(6); OAc, 9-PF(6)). The molecular structures of 6, 7, and 10-PF(6) were determined by X-ray diffraction analysis. The chemical behavior of these compounds in solution was analyzed both by cyclic voltammetry in DMF and absorption UV-vis spectroscopy in an aqueous buffer. Overall, the stability of these gold compounds was found to be acceptable for the cellular studies. For all complexes, relevant antiproliferative activities in vitro were documented against A2780 human ovarian carcinoma cells, either resistant or sensitive to cisplatin, with IC(50) values falling in the low micromolar or even in the nanomolar range. The investigated gold compounds were found to overcome resistance to cisplatin to a large degree. Results are interpreted and discussed in the frame of current knowledge on cytotoxic and antitumor gold compounds.

Epigenetics and chemoresistance in colorectal cancer: an opportunity for treatment tailoring and novel therapeutic strategies.

Colorectal cancer is the second leading cause of cancer-related deaths in the world. Despite many therapeutic opportunities, prognosis remains dismal for patients with metastatic disease, and a significant portion of early-stage patients develop recurrence after chemotherapy. Epigenetic gene regulation is a major mechanism of cancer initiation and progression, through the inactivation of several tumor suppressor genes. Emerging evidence indicates that epigenetics may also play a key role in the development of chemoresistance. In the present review, we summarize epigenetic mechanisms triggering resistance to three commonly used agents in colorectal cancer: 5-fluorouracil, irinotecan and oxaliplatin. Those epigenetic biomarkers may help stratify colorectal cancer patients and develop a tailored therapeutic approach. In addition, epigenetic modifications are reversible through specific drugs: histone-deacetylase and DNA-methyl-transferase inhibitors. Preclinical studies suggest that these drugs may reverse chemoresistance in colorectal tumors. In conclusion, an epigenetic approach to colorectal cancer chemoresistance may pave the way to personalized treatment and to innovative therapeutic strategies.

Special Issue: "Gastrointestinal Cancers and Personalized Medicine".

Gastrointestinal cancers represent more than 25% of all diagnosed cancers and more than 36% of cancer-related deaths worldwide [...].