Role of gemcitabine in ovarian cancer treatment

Cytosolic 5'-Nucleotidase III and Nucleoside Triphosphate Diphosphohydrolase 1 Dephosphorylate the Pharmacologically Active Metabolites of Gemcitabine and Emtricitabine

Gemcitabine (dFdC) and emtricitabine (FTC) are first-line drugs that are used for the treatment of pancreatic cancer and human immunodeficiency virus, respectively. The above drugs must undergo sequential phosphorylation to become pharmacologically active. Interindividual variability associated with the responses of the above drugs has been reported. The molecular mechanisms underlying the observed variability are yet to be elucidated. Although this could be multifactorial, nucleotidases may be involved in the dephosphorylation of drug metabolites due to their structural similarity to endogenous nucleosides. With these in mind, we performed in vitro assays using recombinant nucleotidases to assess their enzymatic activities toward the metabolites of dFdC and FTC. From the above in vitro experiments, we noticed the dephosphorylation of dFdC-monophosphate in the presence of two 5'-nucleotidases (5'-NTs), cytosolic 5'-nucleotidase IA (NT5C1A) and cytosolic 5'-nucleotidase III (NT5C3), individually. Interestingly, FTC monophosphate was dephosphorylated only in the presence of NT5C3 enzyme. Additionally, nucleoside triphosphate diphosphohydrolase 1 (NTPDase 1) exhibited enzymatic activity toward both triphosphate metabolites of dFdC and FTC. Enzyme kinetic analysis further revealed Michaelis-Menten kinetics for both NT5C3-mediated dephosphorylation of monophosphate metabolites, as well as NTPDase 1-mediated dephosphorylation of triphosphate metabolites. Immunoblotting results confirmed the presence of NT5C3 and NTPDase 1 in both pancreatic and colorectal tissue that are target sites for dFdC and FTC treatment, respectively. Furthermore, sex-specific expression patterns of NT5C3 and NTPDase 1 were determined using mass spectrometry-based proteomics approach. Based on the above results, NT5C3 and NTPDase 1 may function in the control of the levels of dFdC and FTC metabolites. SIGNIFICANCE STATEMENT: Emtricitabine and gemcitabine are commonly used drugs for the treatment of human immunodeficiency virus and pancreatic cancer. To become pharmacologically active, both the above drugs must be phosphorylated. The variability in the responses of the above drugs can lead to poor clinical outcomes. Although the sources of drug metabolite concentration variability are multifactorial, it is vital to understand the role of nucleotidases in the tissue disposition of the above drug metabolites due to their structural similarities to endogenous nucleosides.

Exploring the tumor immune microenvironment in ovarian cancer: a way-out to the therapeutic roadmap

INTRODUCTION

Despite cancer treatment strides, mortality due to ovarian cancer remains high globally. While immunotherapy has proven effective in treating cancers with low cure rates, it has limitations. Growing evidence suggests that both tumoral and non-tumoral components of the tumor immune microenvironment (TIME) play a significant role in cancer growth. Therefore, developing novel and focused therapy for ovarian cancer is critical. Studies indicate that TIME is involved in developing ovarian cancer, particularly genome-, transcriptome-, and proteome-wide studies. As a result, TIME may present a prospective therapeutic target for ovarian cancer patients.

AREAS COVERED

We examined several TIME-targeting medicines and the connection between TIME and ovarian cancer. The key protagonists and events in the TIME and therapeutic strategies that explicitly target these events in ovarian cancer are discussed.

EXPERT OPINION

We highlighted various targeted therapies against TIME in ovarian cancer, including anti-angiogenesis therapies and immune checkpoint inhibitors. While these therapies are in their infancy, they have shown promise in controlling ovarian cancer progression. The use of 'omics' technology is helping in better understanding of TIME in ovarian cancer and potentially identifying new therapeutic targets. TIME-targeted strategies could account for an additional treatment strategy when treating ovarian cancer.

Triple-Combination Immunogenic Nanovesicles Reshape the Tumor Microenvironment to Potentiate Chemo-Immunotherapy in Preclinical Cancer Models

Immune checkpoint blockade (ICB) therapies have had a tremendous impact on cancer therapy. However, most patients harbor a poorly immunogenic tumor microenvironment (TME), presenting overwhelming de novo refractoriness to ICB inhibitors. To address these challenges, combinatorial regimens that employ chemotherapies and immunostimulatory agents are urgently needed. Here, a combination chemoimmunotherapeutic nanosystem consisting of a polymeric monoconjugated gemcitabine (GEM) prodrug nanoparticle decorated with an anti-programmed cell death-ligand 1 (PD-L1) antibody (αPD-L1) on the surface and a stimulator of interferon genes (STING) agonist encapsulated inside is developed. Treatment with GEM nanoparticles upregulates PD-L1 expression in ICB-refractory tumors, resulting in augmented intratumor drug delivery in vivo and synergistic antitumor efficacy via activation of intratumor CD8⁺ T cell responses. Integration of a STING agonist into the αPD-L1-decorated GEM nanoparticles further improves response rates by transforming low-immunogenic tumors into inflamed tumors. Systemically administered triple-combination nanovesicles induce robust antitumor immunity, resulting in durable regression of established large tumors and a reduction in the metastatic burden, coincident with immunological memory against tumor rechallenge in multiple murine tumor models. These findings provide a design rationale for synchronizing STING agonists, PD-L1 antibodies, and chemotherapeutic prodrugs to generate a chemoimmunotherapeutic effect in treating ICB-nonresponsive tumors.

A comprehensive update on the structure and synthesis of potential drug targets for combating the coronavirus pandemic caused by SARS-CoV-2

The outbreak of the coronavirus pandemic COVID-19 created by its severe acute respiratory syndrome corona virus-2 (SARS-CoV-2) variant, known for producing a very severe acute respiratory syndrome, has created an unprecedented situation by its continual assault around the world. The crisis caused by the SARS-CoV-2 variant has been a global challenge, calling to mitigate this unprecedented pandemic that has engulfed the whole world. Since the outbreak and spread of COVID-19, many researchers globally have been grappling to find new clinically trialed active drugs with anti-COVID-19 activity, from antimalarial drugs to JAK inhibitors, antiviral drugs, immune suppressants, and so forth. This article presents a brief discussion on the activity and synthesis of some active molecules such as favipiravir, hydroxychloroquine, pirfenidone, remdesivir, lopinavir, camostat, chloroquine, baricitinib, molnupiravir, and so forth, which are under trial.

Decreased risk of ovarian cancer associated with rs9898876 sex hormone-binding globulin gene variant

BACKGROUND

Ovarian cancer (OC) is one of the most common gynecologic cancers,with significant morbidity and mortality. The risk of OC is influenced by hormone status, of which sex hormone-binding globulin (SHBG), which influences the serum availability of steroid sex hormones, is implicated in the pathogenesis and evolution of OC. The aim of this study is to evaluate the involvement of common SHBG gene variants in OC susceptibility and evolution.

MATERIALS

A case control study including 71 OC patients and 74 cancer-free controls, who were genotyped for rs9898876, rs13894, rs1799941 and rs6257 SHBG SNP. Genotyping was done by the allelic discrimination method, using VIC- and FAM-labeled primers.

RESULTS

The minor allele frequencies of rs9898876, rs13894, rs1799941 and rs6257 SHBG SNP was comparable between OC cases and control women, implying no significant associations of the tested variants and overall OC risk. Taking homozygous wild-type genotype as reference (OR = 1.00), heterozygous rs9898876 (G/T), and minor allele-carrying genotypes [G/T + T/T] were associated with reduced risk of OC. While rs9898876 heterozygosity (G/T) was predictive of OC occurrence, no significant association of the remaining three tested SNPs was noted with altered risk of OC. Irrespective of FIGO staging, the four tested SHBG SNPs were not associated with the clinical progression of OC.

CONCLUSIONS

In conclusion, SHBG rs9898876 is associated with a decreased risk of OC, and thus constitutes a potential diagnostic biomarker of OC.

Interaction Analysis of MRP1 with Anticancer Drugs Used in Ovarian Cancer: In Silico Approach

Multidrug resistance (MDR) is one of the major therapeutic challenges that limits the efficacy of chemotherapeutic response resulting in poor prognosis of ovarian cancer (OC). The multidrug resistance protein 1 (MRP1) is a membrane-bound ABC transporter involved in cross resistance to many structurally and functionally diverse classes of anticancer drugs including doxorubicin, taxane, and platinum. In this study, we utilize homology modelling and molecular docking analysis to determine the binding affinity and the potential interaction sites of MRP1 with Carboplatin, Gemcitabine, Doxorubicin, Paclitaxel, and Topotecan. We used AutoDock Vina scores to compare the binding affinities of the anticancer drugs against MRP1. Our results depicted Carboplatin < Gemcitabine < Topotecan < Doxorubicin < Paclitaxel as the order of binding affinities. Paclitaxel has shown the highest binding affinity whereas Carboplatin displayed the lowest affinity to MRP1. Interestingly, our data showed that Carboplatin, Paclitaxel, and Topotecan bind specifically to Asn510 residue in the transmembrane domains 1 of the MRP1. Our results suggest that Carboplatin could be an appropriate therapeutic choice against MRP1 in OC as it couples weakly with Carboplatin. Further, our findings also recommend opting Carboplatin with Gemcitabine as a combinatorial chemotherapeutic approach to overcome MDR phenotype associated with recurrent OC.

Current Treatments and New Possible Complementary Therapies for Epithelial Ovarian Cancer

Epithelial ovarian cancer (EOC) is one of the deadliest gynaecological malignancies. The late diagnosis is frequent due to the absence of specific symptomatology and the molecular complexity of the disease, which includes a high angiogenesis potential. The first-line treatment is based on optimal debulking surgery following chemotherapy with platinum/gemcitabine and taxane compounds. During the last years, anti-angiogenic therapy and poly adenosine diphosphate-ribose polymerases (PARP)-inhibitors were introduced in therapeutic schemes. Several studies have shown that these drugs increase the progression-free survival and overall survival of patients with ovarian cancer, but the identification of patients who have the greatest benefits is still under investigation. In the present review, we discuss about the molecular characteristics of the disease, the recent evidence of approved treatments and the new possible complementary approaches, focusing on drug repurposing, non-coding RNAs, and nanomedicine as a new method for drug delivery.

Drug repurposing for the treatment of COVID-19: Pharmacological aspects and synthetic approaches

In December 2019, a new variant of SARS-CoV emerged, the so-called acute severe respiratory syndrome coronavirus 2 (SARS-CoV-2). This virus causes the new coronavirus disease (COVID-19) and has been plaguing the world owing to its unprecedented spread efficiency, which has resulted in a huge death toll. In this sense, the repositioning of approved drugs is the fastest way to an effective response to a pandemic outbreak of this scale. Considering these facts, in this review we provide a comprehensive and critical discussion on the chemical aspects surrounding the drugs currently being studied as candidates for COVID-19 therapy. We intend to provide the general chemical community with an overview on the synthetic/biosynthetic pathways related to such molecules, as well as their mechanisms of action against the evaluated viruses and some insights on the pharmacological interactions involved in each case. Overall, the review aims to present the chemical aspects of the main bioactive molecules being considered to be repositioned for effective treatment of COVID-19 in all phases, from the mildest to the most severe.

A randomized phase II evaluation of weekly gemcitabine plus pazopanib versus weekly gemcitabine alone in the treatment of persistent or recurrent epithelial ovarian, fallopian tube or primary peritoneal carcinoma

OBJECTIVE

Angiogenesis inhibition is a valuable strategy for ovarian cancer (EOC). Pazopanib (paz) is a potent small molecular inhibitor of VEGF-1, -2, -3, PDGFR, c-kit, and has activity as a single agent in ovarian cancer. We designed a trial to assess the benefit of adding paz to gemcitabine (gem) in patients with recurrent EOC.

METHODS

An open-label, randomized, multi-site, phase 2 trial was conducted (NCT01610206) including patients with platinum resistant or sensitive disease, ≤ 3 prior lines of chemotherapy, and measurable/evaluable disease. Patients were randomly assigned to weekly gem 1000 mg/m² on days 1 and 8 of a 21 day cycle, with or without paz 800 mg QD, stratified by platinum sensitivity and number of prior lines (1 vs 2 or 3). The primary endpoint was PFS.

RESULTS

148 patients were enrolled 2012-2017. Median age was 63 years (30-82); 60% were platinum resistant; median surveillance was 13 months (0.4-54 months). Median PFS was 5.3 (95% CI, 4.2-5.8) vs 2.9 months (95% CI, 2.1-4.1) in the gem arm. The PFS effect was most pronounced in the platinum resistant group (5.32 vs 2.33 months Tarone-Ware p < 0.001). There was no difference in OS. Overall RR (PR 20% vs 11%, Chi-squre p = 0.02) and DCR (80% vs 60%, Chi-square p < 0.001) were higher in the combination. High grade AEs in the combination arm included ≥ Grade 3: hypertension (15%), neutropenia (35%), and thrombocytopenia (12%).

CONCLUSIONS

The addition of paz to gem enhanced anti-tumor activity; those with platinum-resistant disease derived the most benefit from combination therapy, even in the setting of receiving prior bevacizumab.

Synthesis and antitumor activities investigation of a C-nucleoside analogue of ribavirin

SRO-91 is a non-natural ribofuranosyl-1,2,3-triazole C-nucleoside obtained by a synthetic sequence involving a C-alkynyl glycosylation mediated by metallic indium and a Huisgen cycloaddition for the construction of the triazole. Its structure is close to the one of ribavirin, a drug presenting a broad-spectrum against viral infections. SRO-91 antitumor activities were investigated on 9 strains of tumor cells and IC₅₀ of the order of 1 μM were obtained on A431 epidermoid carcinoma cells and B16F10 skin melanoma cells. In addition, studies of ovarian tumor cell inhibitions show an interesting activity in regard to the need for new drugs for this pathology. Finally, cytotoxicity and mouse toxicity studies reveal a favorable therapeutic index for SRO-91.

Management of recurrent ovarian cancer: when platinum-based regimens are not a therapeutic option

Ovarian cancer relapses have been traditionally classified according to the platinum-free interval, leading to an arbitrary categorization of possible scenarios and treatment options. Its relevance in assessing treatment strategies has been revised in the last several years, as the panorama is constantly changing in the era of personalized medicine and targeted therapies. Factors to be considered while defining the best management of recurrent disease, and, consequently, the available treatment alternatives are increasing. Platinum remains one of the milestones of ovarian cancer treatment, but for some patients it might not be an ideal choice for several reasons other than limited platinum sensitivity. This review aims to analyze the scenarios in which platinum is not considered suitable in the management of patients with recurrent ovarian cancer, and the currently available alternatives.

Nanotechnology and Immunotherapy in Ovarian Cancer: Tracing New Landscapes

Ovarian cancer (OC) is the seventh most common cancer in women worldwide. Standard therapeutic treatments involve debulking surgery combined with platinum-based chemotherapies. Of the patients with advanced-stage cancer who initially respond to current treatments, 50%-75% relapse. Immunotherapy-based approaches aimed at boosting antitumor immunity have recently emerged as promising tools to challenge tumor progression. Treatments with inhibitors of immune checkpoint molecules have shown impressive results in other types of tumors. However, only 15% of checkpoint inhibitors evaluated have proven successful in OC due to the immunosuppressive environment of the tumor and the transport barriers. This limits the efficacy of the existing immunotherapies. Nanotechnology-based delivery systems hold the potential to overcome such limitations. Various nanoformulations including polymeric, liposomes, and lipid-polymer hybrid nanoparticles have already been proposed to improve the biodistribution and targeting capabilities of drugs against tumor-associated immune cells, including dendritic cells and macrophages. In this review, we examine the impact of immunotherapeutic approaches that are currently under consideration for the treatment of OC. In this review, we also provide a comprehensive analysis of the existing nanoparticle-based synthetic strategies and their limitations and advantages over standard treatments. Furthermore, we discuss how the strength of the combination of nanotechnology with immunotherapy may help to overcome the current therapeutic limitations associated with their individual application and unravel a new paradigm in the treatment of this malignancy.

Genome-scale CRISPR/Cas9 screen determines factors modulating sensitivity to ProTide NUC-1031

Gemcitabine is a fluoropyrimidine analogue that is used as a mainstay of chemotherapy treatment for pancreatic and ovarian cancers, amongst others. Despite its widespread use, gemcitabine achieves responses in less than 10% of patients with metastatic pancreatic cancer and has a very limited impact on overall survival due to intrinsic and acquired resistance. NUC-1031 (Acelarin), a phosphoramidate transformation of gemcitabine, was the first anti-cancer ProTide to enter the clinic. We find it displays important in vitro cytotoxicity differences to gemcitabine, and a genome-wide CRISPR/Cas9 genetic screening approach identified only the pyrimidine metabolism pathway as modifying cancer cell sensitivity to NUC-1031. Low deoxycytidine kinase expression in tumour biopsies from patients treated with gemcitabine, assessed by immunostaining and image analysis, correlates with a poor prognosis, but there is no such correlation in tumour biopsies from a Phase I cohort treated with NUC-1031.

Combination of weekly topotecan and gemcitabine as a salvage treatment in patients with recurrent ovarian cancer: a phase I study

BACKGROUND

Evaluation of safety of the weekly intravenous gemcitabine/topotecan combination as salvage treatment in patients with recurrent epithelial ovarian cancer.

METHODS

Twenty-four women with histologically-proven relapsed ovarian cancer (ROC) were enrolled in the study. Topotecan (1.75 mg/m2 IV) along with escalated doses of gemcitabine (starting dose 700 mg/m2 with increments of 100 mg/m2) were administered on days 1, 8, and 15 every 28 days. The maximum tolerated dose (MTD) and the dose-limiting toxicity of the combination were evaluated at the first cycle.

RESULTS

Twenty-four ROC patients were enrolled in six dose-levels. Most patients had high-grade serous metastatic ovarian cancer (41.7%) and performance status score of 0-1 (95.8%). For 12 patients (50%) treatment was 2nd line and for 12 >2nd line. Eighty-eight cycles were administered with a median of three cycles per patient. The MTD was not reached and grade 3-4 (3.4% and 2.3% of cycles, respectively) neutropenia and grade 4 (3.4% of cycles) thrombocytopenia were the main adverse events. There was no case of febrile neutropenia. Non-hematologic toxicity was mild with grade 2 fatigue being the most frequent complain. The recommended MTD doses of the combination were topotecan 1.75 mg/m2 and gemcitabine 1200 mg/m2 on days 1, 8, and 15 every 28 days. Two complete (8.3%) and three (12.5%) partial responses were achieved (ORR: 20.8%).

CONCLUSIONS

The weekly administration of gemcitabine/topotecan regimen in patients with pretreated metastatic ovarian cancer is an active chemotherapy combination, even in heavily pretreated patients, with a manageable toxicity profile which merits further investigation.

Formulation and Pharmacokinetics of HSA-core and PLGA-shell Nanoparticles for Delivering Gemcitabine

Gemcitabine-loaded core-shell nanoparticles (CSNPs), comprised of a cross-linked HSA-core and PLGA-shell, were prepared through a modified double emulsification method, and the processing parameters were systematically investigated. The optimized CSNPs had a particle size of 241 ± 36.2 nm and an encapsulation efficiency of 41.52%. The core-shell structure was characterized by optical microscope (OM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The amorphous nature of the encapsulated drug was confirmed by differential scanning calorimetry (DSC) and X-ray diffraction (XRD). An in vitro release study demonstrated that the CSNPs had an improved sustained release profile controlled by erosion of materials in combination with drug diffusion. In vivo pharmacokinetics of CSNPs obtained a bigger area under concentration-time curve (AUC), t _1/2, and C _max compared to free drug solution. The results suggest that HSA-PLGA-based CSNPs can be a promising carrier for the sustained release of gemcitabine.

A brief review of the management of platinum-resistant-platinum-refractory ovarian cancer

Ovarian cancer, which ranks fifth in cancer deaths among women, is the most lethal gynecologic malignancy. Epithelial ovarian cancer (EOC) is the most common histologic type, with the 5-year survival for all stages estimated at 45.6%. This rate increases to more than 70% in the minority of patients who are diagnosed at an early stage, but declines to 35% in the vast majority of patients diagnosed at advanced stage. Recurrent EOC is incurable. Platinum sensitivity (or lack thereof) is a major determinant of prognosis. The current standard treatment is primary surgery followed by platinum-based chemotherapy. In recurrent platinum-resistant/platinum-refractory EOC, sequential single-agent salvage chemotherapy is superior to multiagent chemotherapy. Multiagent regimens increase toxicity without clear benefit; however, no preferred sequence of single agents is recommended. The impact of targeted therapies and immunotherapies on progression-free survival and overall survival, which remains dismal, is under active investigation. Currently, clinical trials offer the best hope for the development of a new treatment paradigm in this recalcitrant disease.

The role of sex hormones and steroid receptors on female reproductive cancers

Sex steroids have been widely described to be associated with a number of human diseases, including hormone-dependent tumors. Several studies have been concerned about the factors regulating the availability of sex steroids and its importance in the pathophysiological aspects of the reproductive cancers in women. In premenopausal women, large fluctuations in the concentration of circulating estradiol (E2) and progesterone (P4) orchestrate many events across the menstrual cycle. After menopause, the levels of circulating E2 and P4 decline but remain at high concentration in the peripheral tissues. Notably, there is a strong relationship between circulating sex hormones and female reproductive cancers (e.g. ovarian, breast, and endometrial cancers). These hormones activate a number of specific signaling pathways after binding either to estrogen receptors (ERs), especially ERα, ERα36, and ERβ or progesterone receptors (PRs). Importantly, the course of the disease will depend on particular transactivation pathway. Identifying ER- or PR-positive tumors will benefit patients in terms of proper endocrine therapy. Based on hormonal responsiveness, effective prevention methods for ovarian, breast, and endometrial cancers represent a special opportunity for women at risk of malignancies. Hormone replacement therapy (HRT) might significantly increase the risk of these cancer types, and endocrine treatments targeting ER signaling may be helpful against E2-dependent tumors. This review will present the role of sex steroids and their receptors associated with the risk of developing female reproductive cancers, with emphasis on E2 levels in pre and postmenopausal women. In addition, new therapeutic strategies for improving the survival rate outcomes in women will be addressed.

Nanoscale Coordination Polymers Codeliver Carboplatin and Gemcitabine for Highly Effective Treatment of Platinum-Resistant Ovarian Cancer

Due to the ability of ovarian cancer (OCa) to acquire drug resistance, it has been difficult to develop efficient and safe chemotherapy for OCa. Here, we examined the therapeutic use of a new self-assembled core-shell nanoscale coordination polymer nanoparticle (NCP-Carbo/GMP) that delivers high loadings of carboplatin (28.0 ± 2.6 wt %) and gemcitabine monophosphate (8.6 ± 1.5 wt %). A strong synergistic effect was observed between carboplatin and gemcitabine against platinum-resistant OCa cells, SKOV-3 and A2780/CDPP, in vitro. The coadministration of carboplatin and gemcitabine in the NCP led to prolonged blood circulation half-life (11.8 ± 4.8 h) and improved tumor uptake of the drugs (10.2 ± 4.4% ID/g at 24 h), resulting in 71% regression and 80% growth inhibition of SKOV-3 and A2780/CDDP tumors, respectively. Our findings demonstrate that NCP particles provide great potential for the codelivery of multiple chemotherapeutics for treating drug-resistant cancer.

A phase 1/2 study combining gemcitabine, Pegintron and p53 SLP vaccine in patients with platinum-resistant ovarian cancer

Purpose

Preclinical tumor models show that chemotherapy has immune modulatory properties which can be exploited in the context of immunotherapy. The purpose of this study was to determine the feasibility and immunogenicity of combinations of such an immunomodulatory chemotherapeutic agent with immunotherapy, p53 synthetic long peptide (SLP) vaccine and Pegintron (IFN-α) in patients with platinum-resistant p53-positive epithelial ovarian cancer (EOC).

Experimental design

This is a phase 1/2 trial in which patients sequential 6 cycles of gemcitabine (1000 mg/kg² iv; n = 3), gemcitabine with Pegintron before and after the first gemcitabine cycle (Pegintron 1 μg/kg sc; n = 6), and gemcitabine and Pegintron combined with p53 SLP vaccine (0.3 mg/peptide, 9 peptides; n = 6). At baseline, 22 days after the 2^nd and 6^th cycle, blood was collected for immunomonitoring. Toxicity, CA-125, and radiologic response were evaluated after 3 and 6 cycles of chemotherapy.

Results

None of the patients enrolled experienced dose-limiting toxicity. Predominant grade 3/4 toxicities were nausea/vomiting and dyspnea. Grade 1/2 toxicities consisted of fatigue (78%) and Pegintron-related flu-like symptoms (72%). Gemcitabine reduced myeloid-derived suppressor cells (p = 0.0005) and increased immune-supportive M1 macrophages (p = 0.04). Combination of gemcitabine and Pegintron stimulated higher frequencies of circulating proliferating CD4+ and CD8+ T-cells but not regulatory T-cells. All vaccinated patients showed strong vaccine-induced p53-specific T-cell responses.

Conclusion

Combination of gemcitabine, the immune modulator Pegintron and therapeutic peptide vaccination is a viable approach in the development of combined chemo-immunotherapeutic regimens to treat cancer.

Gemcitabine-oxaliplatin (GEMOX) for epithelial ovarian cancer patients resistant to platinum-based chemotherapy

BACKGROUND

Patients with platinum-resistant epithelial ovarian cancer (EOC) experience poor outcome. Currently, no clearly superior management strategy exists for platinum-resistant EOC patients.

PURPOSE

Analyze the efficacy and safety of gemcitabine-oxaliplatin (GEMOX) in platinum resistant EOC patients.

PATIENTS AND METHODS

Thirty-two patients with platinum-based resistant EOC were included. Studied patients had received GEM at the dose of 1000mg/m(2) on days 1 and 8 and OX 100mg/m(2) on day 1, administered over 2h 30min after GEM infusion of 3week treatment cycle.

RESULTS

In the evaluation of tumor response, none of patients had achieved CR while PR, SD, were observed in 7 (21.9%), 9 (28.1%) respectively, clinical benefit (CR+PR+SD) was recorded in 50% of patients while PD was observed in 16 (50%) patients. In regard to survival, the median value of OS was 10.5months (range, 2.2-17.5months). The median value of PFS was 6.37months (range, 1-17.5months). The one-year OS rate was 34.4% and the one-year PFS rate was 12.5%. Concerning hematological toxicity grade 3 neutropenia was recorded in 4 (12.5%) patients while grade 4 febrile neutropenia was recorded in 2 (6.3%) patients and grade 4 anemia was represented by 3.1%. Grade 1-2 fatigue was the most common non-hematological toxicity and represented by 65.6% of patients. Grade 3 non hematological toxicity was recorded with nausea/vomiting and hepatic toxicity represented by 3.1% for both.

CONCLUSION

The GEMOX combination is a regimen with a moderate therapeutic efficacy and tolerable toxic side effects in patients with platinum-resistant EOC.

Gemcitabine and Chlorotoxin Conjugated Iron Oxide Nanoparticles for Glioblastoma Therapy

Many small-molecule anti-cancer drugs have short blood half-lives and toxicity issues due to non-specificity. Nanotechnology has shown great promise in addressing these issues. Here, we report the development of an anti-cancer drug gemcitabine-conjugated iron oxide nanoparticle for glioblastoma therapy. A glioblastoma targeting peptide, chlorotoxin, was attached after drug conjugation. The nanoparticle has a small size (~32 nm) and uniform size distribution (PDI ≈ 0.1), and is stable in biological medium. The nanoparticle effectively enter cancer cells without losing potency compared to free drug. Significantly, the nanoparticle showed a prolonged blood half-life and the ability to cross the blood-brain barrier in wild type mice.

Homologous Recombination Deficiency: Exploiting the Fundamental Vulnerability of Ovarian Cancer

Approximately 50% of epithelial ovarian cancers (EOC) exhibit defective DNA repair via homologous recombination (HR) due to genetic and epigenetic alterations of HR pathway genes. Defective HR is an important therapeutic target in EOC as exemplified by the efficacy of platinum analogues in this disease, as well as the advent of PARP inhibitors, which exhibit synthetic lethality when applied to HR-deficient cells. Here, we describe the genotypic and phenotypic characteristics of HR-deficient EOCs, discuss current and emerging approaches for targeting these tumors, and present challenges associated with these approaches, focusing on development and overcoming resistance.

SIGNIFICANCE

Defective DNA repair via HR is a pivotal vulnerability of EOC, particularly of the high-grade serous histologic subtype. Targeting defective HR offers the unique opportunity of exploiting molecular differences between tumor and normal cells, thereby inducing cancer-specific synthetic lethality; the promise and challenges of these approaches in ovarian cancer are discussed in this review.

Homologous Recombination Deficiency: Exploiting the Fundamental Vulnerability of Ovarian Cancer

Approximately 50% of epithelial ovarian cancers (EOC) exhibit defective DNA repair via homologous recombination (HR) due to genetic and epigenetic alterations of HR pathway genes. Defective HR is an important therapeutic target in EOC as exemplified by the efficacy of platinum analogues in this disease, as well as the advent of PARP inhibitors, which exhibit synthetic lethality when applied to HR-deficient cells. Here, we describe the genotypic and phenotypic characteristics of HR-deficient EOCs, discuss current and emerging approaches for targeting these tumors, and present challenges associated with these approaches, focusing on development and overcoming resistance.

SIGNIFICANCE

Defective DNA repair via HR is a pivotal vulnerability of EOC, particularly of the high-grade serous histologic subtype. Targeting defective HR offers the unique opportunity of exploiting molecular differences between tumor and normal cells, thereby inducing cancer-specific synthetic lethality; the promise and challenges of these approaches in ovarian cancer are discussed in this review.

Salvage Chemotherapy for Patients With Recurrent or Persistent Ovarian Clear Cell Carcinoma: A Retrospective Study of 164 Cases

The purpose of this study was to evaluate the effects of salvage chemotherapy on recurrent or persistent ovarian clear cell carcinoma (CCC) with the goal of identifying a more rational treatment regimen for this lethal disease.The medical records of patients with CCC were retrospectively reviewed to select patients that were subsequently treated for recurrent or persistent disease.Of the 164 women with recurrent or persistent CCC, 485 chemotherapy courses with 1766 cycles were administered. Overall, the clinical benefit rate (CBR) was 39.4%, and the mean progression-free survival (PFS) was 4.5 months. Grade 3/4 toxicities occurred in 94 courses (19.4%). The CBR for TC was 45.1%, with a PFS of 3.7 months. Compared to that of TC, the CBRs for PC and CC were significantly lower (P = 0.020 and 0.021, respectively). The CBRs and PFS for PAF-C were slightly higher (P = 0.518 and 0.077, respectively), but showed a significantly higher adverse event rate (AER, P = 0.039). The CBR for bevacizumab was 50% with an extraordinarily long PFS (49.8 months). Gemcitabine and oxaliplatin had similar values for CBRs (44.4% and 44.1%) and PFS (2.5 and 3.4 months), respectively. Docetaxel (weekly) exhibited a notably low AER of 2.7%, and topotecan was associated with a relatively long PFS (7.7 months).For cis/carboplatin-pretreated patients, the existing active agents, such as oxaliplatin, gemcitabine, topotecan, and especially bevacizumab, are promising. Docetaxel (weekly) is well tolerated and might offer a particularly viable option for heavily pretreated patients. However, additional research to identify for a continued search for the optimal combination of chemotherapeutics or novel agents is still warranted.

Cytidine Deaminase Axis Modulated by miR-484 Differentially Regulates Cell Proliferation and Chemoresistance in Breast Cancer

There has been little study of how the evolution of chemoresistance in cancer affects other aspects of disease pathogenesis. Here, we show that an important chemoresistance axis driven by cytidine deaminase (CDA) also acts to suppress cell-cycle progression by regulating cyclin E-CDK2 signaling. We found that CDA was regulated by miR-484 in a gemcitabine-resistant model of breast cancer. Elevating miR-484 expression reversed the CDA effects, thereby enhancing gemcitabine sensitivity, accelerating cell proliferation, and redistributing cell-cycle progression. Conversely, elevating CDA to restore its expression counteracted the chemosensitization and cell proliferative effects of miR-484. In clinical specimens of breast cancer, CDA expression was frequently downregulated and inversely correlated with miR-484 expression. Moreover, high expression of CDA was associated with prolonged disease-free survival in studied cohorts. Collectively, our findings established that miR-484-modulated CDA has a dual impact in promoting chemoresistance and suppressing cell proliferation in breast cancer, illustrating the pathogenic tradeoffs associated with the evolution of chemoresistance in this malignant disease.

Clinical Response to Antiestrogen Therapy in Platinum-Resistant Ovarian Cancer Patients and the Role of Tumor Estrogen Receptor Expression Status

Objective

This study aimed to determine the progression-free interval (PFI) for patients with platinum-resistant ovarian cancer on antiestrogen therapy (AET), and to correlate PFI with tumor estrogen receptor (ER) expression status.

Materials and Methods

This single-institution retrospective cohort study investigated platinum-resistant epithelial ovarian, fallopian tube, and primary peritoneal cancers treated with tamoxifen or an aromatase inhibitor from January 1999 to January 2012. Median PFI was calculated and a 95% confidence interval was constructed by bootstrapping. Relationships of PFI with disease characteristics were examined using 1-way analysis of variance or Pearson correlation. Estrogen receptor status of tumor specimens was assessed by immunohistochemistry. Progression-free interval was compared between ER groups with the Mann-Whitney test. Kaplan-Meier estimate was used to determine overall survival.

Results

Ninety-nine patients met inclusion criteria: 77 (78%) received tamoxifen and 22 (22%) an aromatase inhibitor. Patients had a mean of 4 prior chemotherapy regimens (range, 1–14). Median PFI for any AET was 4.0 months (range, 1–49; 95% confidence interval, 3.0–5.0). Progression-free interval was independent of the number of prior treatments and type of AET, but longer with earlier stage at diagnosis. Estrogen receptor status was obtained for 63 patients, 44 were positive and 19 were negative. Progression-free interval was not statistically significant between ER-positive (median, 4.0 months) and ER-negative (median, 2.0 months) tumor status (P= 0.36).

Conclusions

This is the largest study to date investigating AET in heavily pretreated, platinum-resistant ovarian cancer patients. The median PFI of 4.0 months is comparable to standard cytotoxic therapies, and some patients with PFI greater than this median interval had ER-negative tumors. Given the limited adverse effects of AET, as well as low cost including oral administration, this treatment should be considered in all patients with platinum-resistant ovarian cancer.

Defective hCNT1 transport contributes to gemcitabine chemoresistance in ovarian cancer subtypes: overcoming transport defects using a nanoparticle approach

Nucleoside analogs are used as chemotherapeutic options for the treatment of platinum-resistant ovarian cancers. Human concentrative nucleoside transporter 1 (hCNT1) is implicated in sensitizing solid tumors to nucleoside analogs although its role in determining drug efficacy in ovarian cancers remains unclear. Here we examined the functional expression of hCNT1 and compared its contributions toward gemcitabine efficacy in histological subtypes of ovarian cancer. Radioactivity analysis identified hCNT1-mediated (3)H-gemcitabine transport in ovarian cancer cells to be significantly reduced compared with that of normal ovarian surface epithelial cells. Biochemical and immunocytochemical analysis identified that unlike normal ovarian cells which expressed high levels of hCNT1 at the apical cell surface, the transporter was either diminished in expression and/or mislocalized in cell lines of various subtypes of ovarian cancer. Retroviral expression of hCNT1 selectively rescued gemcitabine transport in cell lines representing serous, teratocarcinoma, and endometrioid subtypes, but not clear cell carcinoma (CCC). In addition, exogenous hCNT1 predominantly accumulated in intracytoplasmic vesicles in CCC suggesting defective cellular trafficking of hCNT1 as a contributing factor to transport deficiency. Despite diminution of hCNT1 transport in the majority of ovarian cancers and apparent trafficking defects with CCC, the chemotherapeutic efficacy of gemcitabine was broadly enhanced in all subtypes when delivered via engineered nanoparticles (NPs). Additionally, by bypassing the transport requirement, the delivery of a gemcitabine-cisplatin combination in NP formulation increased their synergistic interactions. These findings uncover hCNT1 as a putative determinant for nucleoside analog chemoresistance in ovarian cancer and may help rationalize drug selection and delivery strategies for various histological subtypes of ovarian cancer.

A linear synthesis of gemcitabine

Gemcitabine, 2'-deoxy-2',2'-difluorocytidine, is currently prescribed against a number of cancers. Here we report a linear synthesis of gemcitabine with a high-yielding direct conversion of 3,5-di-O-benzoyl-2-deoxy-2,2-difluororibose into the corresponding glycosyl urea as the key step, followed by conventional conversion to the cytosine base via the uracil derivative. The process proceeded with modest anomeric selectivity.

Increased Dose Single-agent Gemcitabine in Platinum-taxane Resistant Metastatic Ovarian Cancer

Background

In platinum-taxane resistant epithelial ovarian cancer (EOC), we aimed to determine the effectiveness.

Patients and Methods

Between 2004 and 2013, patients afflicted with platinum-taxane resistant EOC and who were administered a 30-minute i.v. infusion of single-agent gemcitabine at a dose of 1,250 mg/m2 on the 1st, 8th and 15th days, every 28 days, were examined retrospectively.

Results

Twenty-six patients with platinum-taxane resistant EOC were included in the study. The overall survival (OS) was 48 months. The median survival after becoming platinum-taxane resistant was 16 months for the study population. Median time to progression (TTP) and median survival after becoming platinum-taxane resistant for patients who received second-line treatment were 3.3 months and 16 months, respectively; for patients who received third-line treatment with gemcitabine, these were 3.7 months and 19 months, respectively. Administration of gemcitabine as second- and third-line chemotherapy in platinum-taxane resistant EOC, provides similar TTP and OS outcomes (p = 0.4, p = 0.9) with a similar response and toxicity rate.

Conclusions

Second- and third-line gemcitabine at a dose of 1,250 mg/m2 on days 1, 8 and 15 every 28 days as a 30-minute i.v. infusion in platinum-taxane resistant EOC is an effective treatment option with a tolerable and manageable toxicity.

The synthesis of gemcitabine

Gemcitabine is a fluorinated nucleoside currently administered against a number of cancers. It consists of a cytosine base and a 2-deoxy-2,2-difluororibose sugar. The synthetic challenges associated with the introduction of the fluorine atoms, as well as with nucleobase introduction of 2,2-difluorinated sugars, combined with the requirement to have an efficient process suitable for large scale synthesis, have spurred significant activity towards the synthesis of gemcitabine exploring a wide variety of synthetic approaches. In addition, many methods have been developed for selective crystallisation of diastereomeric (including anomeric) mixtures. In that regard, the 2-deoxy-2,2-difluororibose sugar is one of the most investigated fluorinated carbohydrates in terms of its synthesis. The versatility of synthetic methods employed is illustrative of the current state of the art of fluorination methodology for the synthesis of CF2-containing carbohydrates, and involves the use of fluorinated building blocks, as well as nucleophilic and electrophilic fluorination of sugar precursors.

Gemcitabine eliminates double minute chromosomes from human ovarian cancer cells

Double minute chromosomes are cytogenetic manifestations of gene amplification frequently seen in cancer cells. Genes amplified on double minute chromosomes include oncogenes and multi-drug resistant genes. These genes encode proteins which contribute to cancer formation, cancer progression, and development of resistance to drugs used in cancer treatment. Elimination of double minute chromosomes, and therefore genes amplified on them, is an effective way to decrease the malignancy of cancer cells. We investigated the effectiveness of a cancer drug, gemcitabine, on the loss of double minute chromosomes from the ovarian cancer cell line UACC-1598. Gemcitabine is able to decrease the number of double minute chromosomes in cells at a 7500X lower concentration than the commonly used cancer drug hydroxyurea. Amplified genes present on the double minute chromosomes are decreased at the DNA level upon gemcitabine treatment. Gemcitabine, even at a low nanomolar concentration, is able to cause DNA damage. The selective incorporation of double minutes chromatin and γ-H2AX signals into micronuclei provides a strong link between DNA damage and the loss of double minute chromosomes from gemcitabine treated cells. Cells treated with gemcitabine also showed decreased cell growth, colony formation, and invasion. Together, our results suggest that gemcitabine is effective in decreasing double minute chromosomes and this affects the biology of ovarian cancer cells.

Gemcitabine-oxaliplatin (GEMOX) as salvage treatment in pretreated epithelial ovarian cancer patients

Background

Currently, no clearly superior management strategy exists for recurrent, platinum-resistant ovarian cancer. We tested the efficacy and safety of gemcitabine combined with oxaliplatin (GEMOX) in a multicentre phase II clinical trial.

Methods

Forty one patients with recurrent, platinum-resistant ovarian cancer were enrolled. Prior to study entry, all the participants had received at least one platinum-based regimen. Gemcitabine was administered at 1000 mg/m² as protracted infusion (100 min) on day 1, and oxaliplatin at the dose of 100 mg/m² on day 2 in a 2 hour infusion. Cycles were repeated every two weeks.

Results

We observed an overall response rate of 37% [95% Confidence Interval (CI), 22.3–51.7]. Objective responses plus disease stabilization (clinical benefit) occurred in 78% of patients. Median progression-free survival was 6.8 months (95% CI, 5.8–7.8), and median overall survival was 16.5 months (95% CI, 12.2–20.8). Median time to self-reported symptom relief, which was described by 22 out of 27 symptomatic patients (81.5%), was 4 weeks (range, 2–8). Grade 4 neutropenia and febrile neutropenia were observed in 2 (5%) and 1 (2.5%) patients, while grade 3 anemia was encountered in 2 (5%) patients, respectively. The most common adverse effects of any grade were gastrointestinal symptoms, fatigue and neutropenia. Nine patients (22%) experienced mild allergic reaction to oxaliplatin, with no treatment discontinuation.

Conclusions

In our cohort of recurrent, platinum-resistant ovarian cancer patients, GEMOX showed encouraging activity and manageable toxicity. Under circumstances requiring a rapid disease control, this combination regimen may offer a particularly viable option, particularly in heavily pretreated patients.

Complete remission of platinum-refractory primary Fallopian tube carcinoma with third-line gemcitabine plus cisplatin: A case report and review of the literature

Primary Fallopian tube carcinoma (PFTC) is a rare but highly aggressive disease. Currently, treatments are similar to those used in epithelial ovarian carcinoma (EOC), however, there are distinct differences between the two diseases. PFTC tends to recur in the retroperitoneal nodes and distant sites more often than EOC. Limited literature with regard to effective agents in platinum-resistant and -refractory (Pt-R) disease exists, particularly after two lines of consecutive treatment. In this case report, a 47-year-old female with PFTC exhibited recurrence in the liver after postoperative chemotherapy. The patient received paclitaxel and cisplatin combination as first-line chemotherapy and topotecan as a second-line treatment, which is considered platinum-refractory. After the second-line treatment failed, this patient received a gemcitabine plus cisplatin combination as third-line chemotherapy for a total of 6 cycles. The liver metastases regressed rapidly and completely. The patient's progression-free survival (PFS) was 10 months and overall survival (OS) was 45 months. In conclusion, gemcitabine and cisplatin combination is an effective regimen for refractory PFTC even after the failure of two previous lines of consecutive chemotherapy and this warrants further independent investigation.

High sensitive assay employing column switching chromatography to enable simultaneous quantification of an amide prodrug of gemcitabine (LY2334737), gemcitabine, and its metabolite dFdU in human plasma by LC-MS/MS

In this study we report a high sensitive method for the simultaneous analysis of LY2334737 (2'-deoxy-2',2'-difluoro-N-(1-oxo-2-propylpentyl)-cytidine), an amide prodrug of gemcitabine (2', 2'-difluoro-deoxycytidine), along with its active drug gemcitabine and its major metabolite dFdU (2',2'-difluoro-deoxyuridine) by LC-MS/MS. Quantification of all three analytes within a single analysis was challenging because the physio-chemical properties of LY2334737 were significantly different from gemcitabine and dFdU and was accomplished by incorporating column-switching. The assay was fully validated to quantify LY2334737 from 0.1 to 100ng/mL, gemcitabine from 0.25 to 100ng/mL and dFdU from 1 to 1000ng/mL in order to cover the diverse concentration ranges expected in clinical samples. A 25-fold dilution was also validated to accommodate any samples outside this range. Overall, the assay had good accuracy (ranging from -7.0 to 1.2% relative error) and precision (ranging from 2.1 to 8.4% relative standard deviation). Extraction efficiency was greater than 80% for all three analytes and there were no matrix effects. Plasma samples were stable for 24h at room temperature, 660 days in frozen storage, and at least 4 freeze-thaw cycles, at both -20 and -70°C. Data from clinical trials showed that plasma concentrations for LY2334737, gemcitabine, and dFdU were successfully quantified from a single LC-MS/MS analysis and that the assay ranges selected for the three analytes were appropriate and minimized the need for reanalysis.

Preclinical absorption, distribution, metabolism, and excretion of an oral amide prodrug of gemcitabine designed to deliver prolonged systemic exposure

Gemcitabine is an intravenously administered nucleoside analog chemotherapeutic agent. The ability to deliver this agent as an oral drug would allow greater flexibility of administration and patient convenience; however, attempts have been fraught with high first-pass metabolism and potential intestinal toxicity. Alternatively, an amide prodrug of gemcitabine (LY2334737) was discovered, which is able to avoid the extensive first-pass metabolism that occurs following administration of gemcitabine. Preclinical in vitro and in vivo experiments were conducted to evaluate the hydrolysis and pharmacokinetics of LY2334737 and its downstream metabolites. In mice, rats, and dogs, the prodrug is absorbed largely intact across the intestinal epithelium and delivers LY2334737 to systemic circulation. The hydrolysis of LY2334737 is relatively slow, resulting in sustained release of gemcitabine in vivo. In vitro experiments identified carboxylesterase 2 (CES2) as a major enzyme involved in the hydrolysis of LY2334737, but with relatively low intrinsic clearance. Following hydrolysis of the prodrug, gemcitabine is cleared predominantly via the formation of its inactive metabolite dFdU. Both biliary and renal excretion was responsible for the elimination of LY2334737 and its metabolites in both mice and dogs.

Combination therapy with gossypol reveals synergism against gemcitabine resistance in cancer cells with high BCL-2 expression

Although gemcitabine is highly active in several cancer types, intrinsic and acquired drug resistance remains a major challenge. Overexpression of Bcl-2 has been associated with gemcitabine resistance. The aim of this study is to determine whether gossypol can overcome gemcitabine resistance in cell lines with high level of Bcl-2 expression in combination drug therapy. Our study demonstrated that in 10 cell lines derived from different cancers, high Bcl-2 baseline expression was observed in cell lines that were resistant to gemcitabine (GEM-R). Furthermore, synergistic effect of combination therapy was observed in gemcitabine-resistant (GEM-R) cell lines with high Bcl-2 expression, but not in a gemcitabine-sensitive (GEM-S) cell lines regardless of Bcl-2 expression. Gossypol treatment resulted in the decrease of anti-apoptotic genes such as Bcl-2 and Bcl-xl and an upregulation of the pro-apoptotic gene, Noxa. Furthermore, the addition of gossypol to gemcitabine resulted in lower expressions of anti-apoptotic genes compared to gemcitabine alone. Gene expression profiling in GEM-R and GEM-S cell lines suggest that anti-apoptotic genes such as pAkt and PI3KR2 may play important role in gemcitabine resistance, while pro-apoptotic Bcl-2 related genes (Bad, Caspase-6 and Calpain-1) may regulate synergistic interaction in combination therapy.

Outcome of single agent generic gemcitabine in platinum-resistant ovarian cancer, fallopian tube cancer and primary peritoneal adenocarcinoma

Single original gemcitabine is commonly used as salvage treatment in platinum-resistant ovarian cancer, fallopian tube cancer and primary peritoneal adenocarcinoma (PPA) with a satisfactory outcome. However, efficacy data fro this regimen are limited. We therefore conducted a retrospective study to evaluate the outcome of patients who received single-agent generic gemcitabine (GEMITA) after development of clinical platinum resistance. The study period was between May 2008 and December 2010. Gemcitabine was administered intravenously in two different schedules: 1,000 mg/m2 on day 1,8, and 15 every 28 days; and on days 1 and 8 every 21 days with the same dosage. Administration was until disease progression was noted. The response rate was evaluated using the Gynecologic Cancer Intergroup (GCIG ) criteria while toxicity was evaluated according to WHO criteria. Sixty-six patients met the inclusion criteria in the study period. Two-thirds of them received gemcitabine as the second and third line regimen. The overall response rate was 12.1%. The median progression free survival and overall survival was 2 and 10 months, respectively. With the total 550 courses of chemotherapy, the patients developed grades 3 and 4 hematologic toxicity as follows: anemia, 1.5%; leukopenia, 13.7%; neutropenia, 27.3%; and thrombocytopenia, 3.0%. In conclusion, single agent generic gemcitabine revealed a modest efficacy in patients with platinum-resistant ovarian cancer, fallopian tube cancer and PPA without serious toxicity.