Ex vivo analysis of topotecan: advancing the application of laboratory-based clinical therapeutics

A Deep Neural Network for Predicting Synergistic Drug Combinations on Cancer

The exploration of drug combinations presents an opportunity to amplify therapeutic effectiveness while alleviating undesirable side effects. Nevertheless, the extensive array of potential combinations poses challenges in terms of cost and time constraints for experimental screening. Thus, it is crucial to narrow down the search space. Deep learning approaches have gained widespread popularity in predicting synergistic drug combinations tailored for specific cell lines in vitro settings. In the present study, we introduce a novel method termed GTextSyn, which utilizes the integration of gene expression data and chemical structure information for the prediction of synergistic effects in drug combinations. GTextSyn employs a sentence classification model within the domain of Natural Language Processing (NLP), wherein drugs and cell lines are regarded as entities possessing biochemical relevance. Meanwhile, combinations of drug pairs and cell lines are construed as sentences with biochemical relational significance. To assess the efficacy of GTextSyn, we conduct a comparative analysis with alternative deep learning approaches using a standard benchmark dataset. The results from a five-fold cross-validation demonstrate a 49.5% reduction in Mean Square Error (MSE) achieved by GTextSyn, surpassing the performance of the next best method in the regression task. Furthermore, we conduct a comprehensive literature survey on the predicted novel drug combinations and find substantial support from prior experimental studies for many of the combinations identified by GTextSyn.

Unlocking the therapeutic potential of drug combinations through synergy prediction using graph transformer networks

Drug combinations are frequently used to treat cancer to reduce side effects and increase efficacy. The experimental discovery of drug combination synergy is time-consuming and expensive for large datasets. Therefore, an efficient and reliable computational approach is required to investigate these drug combinations. Advancements in deep learning can handle large datasets with various biological problems. In this study, we developed a SynergyGTN model based on the Graph Transformer Network to predict the synergistic drug combinations against an untreated cancer cell line expression profile. We represent the drug via a graph, with each node and edge of the graph containing nine types of atomic feature vectors and four bonds features, respectively. The cell lines represent based on their gene expression profiles. The drug graph was passed through the GTN layers to extract a generalized feature map for each drug pairs. The drug pair extracted features and cell-line gene expression profiles were concatenated and subsequently subjected to processing through multiple densely connected layers. SynergyGTN outperformed the state-of-the-art methods, with a receiver operating characteristic area under the curve improvement of 5% on the 5-fold cross-validation. The accuracy of SynergyGTN was further verified through three types of cross-validation tests strategies namely leave-drug-out, leave-combination-out, and leave-tissue-out, resulting in improvement in accuracy of 8%, 1%, and 2%, respectively. The Astrazeneca Dream dataset was utilized as an independent dataset to validate and assess the generalizability of the proposed method, resulting in an improvement in balanced accuracy of 13%. In conclusion, SynergyGTN is a reliable and efficient computational approach for predicting drug combination synergy in cancer treatment. Finally, we developed a web server tool to facilitate the pharmaceutical industry and researchers, as available at: http://nsclbio.jbnu.ac.kr/tools/SynergyGTN/.

Capsaicin: A chili pepper bioactive phytocompound with a potential role in suppressing cancer development and progression

Cancer profoundly influences morbidity and fatality rates worldwide. Patients often have dismal prognoses despite recent improvements in cancer therapy regimens. However, potent biomolecules derived from natural sources, including medicinal and dietary plants, contain biological and pharmacological properties to prevent and treat various human malignancies. Capsaicin is a bioactive phytocompound present in red hot chili peppers. Capsaicin has demonstrated many biological effects, including antioxidant, anti-inflammatory, antimicrobial, and anticarcinogenic capabilities. This review highlights the cellular and molecular pathways through which capsaicin exhibits antineoplastic activities. Our work also depicts the synergistic anticancer properties of capsaicin in conjunction with other natural bioactive components and approved anticancer drugs. Capsaicin inhibits proliferation in various cancerous cells, and its antineoplastic actions in numerous in vitro and in vivo carcinoma models impact oncogenesis, tumor-promoting and suppressor genes, and associated signaling pathways. Capsaicin alone or combined with other phytocompounds or approved antineoplastic drugs triggers cell cycle progression arrest, generating reactive oxygen species and disrupting mitochondrial membrane integrity, ultimately stimulating caspases and promoting death. Furthermore, capsaicin alone or in combination can promote apoptosis in carcinoma cells by enhancing the p53 and c-Myc gene expressions. In conclusion, capsaicin alone or in combination can have enormous potential for cancer prevention and intervention, but further high-quality studies are needed to firmly establish the clinical efficacy of this phytocompound.

Dual-response electrochemical electrode for sensitive monitoring of topotecan and mitomycin as anticancer drugs in real samples

This research paper employed an innovative electrochemical electrode to simultaneously determine topotecan (TPT) and mitomycin (MMC) as anticancer agents. For this purpose, a novel nanocomposite was synthesized using a hydrothermal procedure. The nanocomposites were characterized using FTIR, STEM, FESEM, mapping analysis, EDX, and XRD methods. The novelty of this work is the successful synthesis of Fe₃O₄ decorated on the surface of CuCo₂S₄ (Fe₃O₄@CuCo₂S₄) nanocomposites showed two separate anodic peaks at 0.8 V for TPT and 1.0 V for MMC with potential separation of 0.2 V. This was enough for the simultaneous electrochemical determination of topotecan and mitomycin on a glassy carbon electrode (GCE), simultaneously. At optimized conditions, the developed electrode exhibited linear responses with TPT and MMC concentration in the ranges of 0.01-0.89 and 0.89-8.95 μM for topotecan and 0.1-19.53 μM for mitomycin. The detection limits were observed as 6.94 nM and 80.00 nM for topotecan and mitomycin, respectively. The fabricated Fe₃O₄@CuCo₂S₄/GCE showed high sensitivity, long-term stability, and repeatability towards the sensing of TPT and MMC simultaneously and can be utilized in real samples. The obtained results confirmed that the fabricated Fe₃O₄@CuCo₂S₄/GCE nanocomposites can be utilize in the simultaneous electrochemical determination of topotecan and mitomycin in real samples.

Platinum resistance in gynecologic malignancies: Response, disease free and overall survival are predicted by biochemical signature: A metabolomic analysis

OBJECTIVE

Platinum resistance, defined as the lack of response or relapse within six months of platinum-based chemotherapy, is an important determinant of survival in gynecologic cancer. We used quantitative Mass Spectrometry to identify metabolic signatures that predict platinum resistance in patients receiving chemotherapy for gynecologic cancers.

METHODS

In this study 47 patients with adenocarcinoma of the ovary or uterus who were candidates for carboplatin plus paclitaxel submitted blood for quantitation of metabolites and surgical specimens for the isolation 3-dimensional organoids used to measure individual patient platinum resistance, ex vivo. Results were correlated with response, time to progression and survival.

RESULTS

Of 47 patients, 27 (64.3%) achieved complete remission with a mean time to progression of 1.9 years (± 1.5), disease-free survival of 1.7 years (± 1.4) and overall survival of 2.6 years (± 1.6) and a mean cisplatin lethal concentration 50% (LC50) = 1.15 μg/ml (range 0.4-3.1). Cisplatin LC50's correlated with a non-significant decrease in complete remission (RR [95% CI] =0.76 [0.46-1.27]), diminished disease-free survival (median: 1.15 vs. 2.99 years, p = 0.038) and with biochemical signatures of 186 metabolites. Receiver operating curves (ROC) of lipid ratios, branched chain amino acids and the tryptophan to kynurenine ratio identified patients at the highest risk of relapse and death (AUC = 0.933) with a sensitivity of 92.0% and specificity of 86.0% (p < 0.001).

CONCLUSIONS

Metabolic signatures in gynecologic cancer identify patients at the highest risk of relapse and death offering new diagnostic and prognostic tools for management of the advanced gynecologic tumors.

Development of a Ternary Solid Dispersion Formulation of LW6 to Improve the In Vivo Activity as a BCRP Inhibitor: Preparation and In Vitro/In Vivo Characterization

LW6 (3-[2-(4-adamantan-1-yl-phenoxy)-acetylamino]-4-hydroxy-benzoic acid methyl ester) is a potent inhibitor of drug efflux by the breast cancer resistance protein (BCRP). However, its poor aqueous solubility leads to low bioavailability, which currently limits in vivo applications. Therefore, the present study aimed to develop ternary solid dispersion (SD) formulations in order to enhance the aqueous solubility and dissolution rate of LW6. Various SDs of LW6 were prepared using a solvent evaporation method with different drug/excipient ratios. The solubility and dissolution profiles of LW6 in different SDs were examined, and F8-SD which is composed of LW6, poloxamer 407, and povidone K30 at a weight ratio of 1:5:8 was selected as the optimal SD. The structural characteristics of F8-SD were also examined using Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), X-ray powder diffraction (XRPD), and scanning electron microscopy (SEM). In the acidic to neutral pH range, F8-SD achieved rapid dissolution with a drug release of 76–81% within 20 min, while the dissolution of pure LW6 was negligible. The XRPD patterns indicated that F8-SD probably enhanced the solubility and dissolution of LW6 by changing the drug crystallinity to an amorphous state, in addition to the solubilizing effect of the hydrophilic carriers. Furthermore, F8-SD significantly improved the oral bioavailability of topotecan, which is a BCRP substrate, in rats. The systemic exposure of topotecan was enhanced approximately 10-fold by the concurrent use of F8-SD. In conclusion, the ternary SD formulation of LW6 with povidone K30 and poloxamer 407 appeared to be effective at improving the dissolution and in vivo effects of LW6 as a BCRP inhibitor.

Capsaicin synergizes with camptothecin to induce increased apoptosis in human small cell lung cancers via the calpain pathway

Small cell lung cancer (SCLC) is characterized by excellent initial response to chemotherapy and radiation therapy with a majority of the patients showing tumor shrinkage and even remission. However, the challenge with SCLC therapy is that patients inevitably relapse and subsequently do not respond to the first line treatment. Recent clinical studies have investigated the possibility of camptothecin-based combination therapy as first line treatment for SCLC patients. Conventionally, camptothecin is used for recurrent SCLC and has poor survival outcomes. Therefore, drugs which can improve the therapeutic index of camptothecin should be valuable for SCLC therapy. Extensive evidence shows that nutritional compounds like capsaicin (the spicy compound of chili peppers) can improve the anti-cancer activity of chemotherapeutic drugs in both cell lines and animal models. Statistical analysis shows that capsaicin synergizes with camptothecin to enhance apoptosis of human SCLC cells. The synergistic activity of camptothecin and capsaicin is observed in both classical and variant SCLC cell lines and, in vivo, in human SCLC tumors xenotransplanted on chicken chorioallantoic membrane (CAM) models. The synergistic activity of capsaicin and camptothecin are mediated by elevation of intracellular calcium and the calpain pathway. Our data foster hope for novel nutrition based combination therapies in SCLC.

Differential Staining Cytotoxicity assay: a review

Differential Staining Cytotoxicity (DiSC) assay is the prototype for a closely related family of assays based on the concept of total cell kill, or, in other words, cell death occurring in the entire population of tumor cells. It is probably the most versatile of the cell-death end points, in that it (1) can be applied to both solid and hematologic neoplasms, (2) can be applied to specimens in which it is not possible to obtain a pure population of highly enriched tumor cells, and (3) can be applied to a wide variety of drugs, ranging from traditional cytotoxic agents to biological response modifiers with activity mediated through tumor-infiltrating effector cells, to "targeted" kinase inhibitors, and to antivascular agents, such as bevacizumab and pazopanib. The basic principles of the assay are to culture three-dimensional fresh tumor cell clusters in anchorage-independent conditions. At the conclusion of the culture period, Fast Green dye is added to the microwells, the contents of which are then sedimented onto permanent Cytospin centrifuge slides and then counterstained with hematoxylin-eosin or Wright-Giemsa. "Living" cells stain with the cytologic stain in question and can be identified as either normal or neoplastic, based on standard morphologic criteria. "Dead" cells stain blue-green. Nonviable endothelial cells appear as strikingly hyperchromatic, blue-black, and often refractile objects, which may be readily distinguished from other types of dead cells. This assay has been biologically and clinically validated in a number of ways, as described in this chapter.

Clinical relevance of human cancer xenografts as a tool for preclinical assessment: example of in-vivo evaluation of topotecan-based chemotherapy in a panel of human small-cell lung cancer xenografts

Prediction of human tumor response based on preclinical data could reduce the failure rates of subsequent new anticancer drugs clinical development. Human small-cell lung carcinomas (SCLC) are characterized by high initial sensitivity to chemotherapy but a low median survival time because of drug resistance. The aim of this study was to evaluate the therapeutic relevance of a panel of human SCLC xenografts established in our laboratory using one compromising drug in SCLC, topotecan (TPT). Six SCLC xenografts derived from six patients were used: three were sensitive to a combination of etoposide (VP16), cisplatin (CDDP), and ifosfamide (IFO), and three were resistant, as published earlier. Growth inhibition was greater than 84% for five xenografts at doses of 1-2 mg/kg/day. TPT was combined with IFO, etoposide (VP16), and CDDP. IFO improved the efficacy of TPT in three of the five xenografts and complete responses were obtained even with the less TPT-sensitive xenograft. VP16 increased the efficacy of two of four xenografts and complete responses were obtained. The combination of TPT and CDDP did not improve TPT responses for any of the xenografts tested. Semiquantitative reverse transcriptase-PCR of genes involved in drug response, such as topoisomerase I, topoisomerase IIalpha, multidrug resistance 1 (MDR1), multidrug resistance-associated protein (MRP), lung resistance-related protein (LRP), and glutathione S-transferase pi (GSTpi), did not explain the variability in drug sensitivity between SCLC xenografts. In conclusion, these preclinical data mirror those from published clinical studies suggesting that our panel of SCLC xenografts represents a useful tool for preclinical assessment of new treatments.

UV-vis spectra of the anticancer camptothecin family drugs in aqueous solution: specific spectroscopic signatures unraveled by a combined computational and experimental study

The ultraviolet-visible absorption spectrum of camptothecin (CPT) has been been recorded in aqueous solution at pH 5.3, where the equilibrium among the different CPT forms is shifted toward the lactonic one. Time-dependent density functional theory (TD-DFT) computations lead to a remarkable reproduction of the experimental spectrum only upon addition of explicit water molecules in interaction with specific moieties of the camptothecin molecule. Molecular dynamics (MD) simulations enforcing boundary periodic conditions for CPT embedded with 865 water molecules, with a force field derived from DFT computations, show that the experimental spectrum is due to the contributions of CPT molecules with different solvation patterns. A similar solvent effect is observed for several CPT derivatives, including the clinically relevant SN-38 and topotecan drugs. The quantitative agreement between TD-DFT/MD computations and experimental data allow us to identify specific spectroscopic signatures diagnostic of the drug environment and to develop procedures that can be used to monitor the drug-DNA/protein interaction.

Second-line chemotherapy in advanced and metastatic CRC

BACKGROUND

Chemotherapy is widely used in colorectal cancer that has relapsed or failed to respond to first-line treatment.

OBJECTIVES

To determine the efficacy of second-line chemotherapy for the treatment of advanced colorectal cancer.

SEARCH STRATEGY

We performed electronic searches in the following databases: MEDLINE (via PubMed; 1964-September 2007), EMBASE (via OVID; 1980-September 2007) and The Cochrane Library 2007, Issue 2.

SELECTION CRITERIA

Studies assessing the efficacy of second-line chemotherapy (single or combined treatment with any chemotherapeutic agent, at any dose and number of cycles) in patients with advanced colorectal cancer that progressed, recurred or did not respond to first-line chemotherapy.

DATA COLLECTION AND ANALYSIS

A descriptive analysis of the included trials was performed, due to the huge clinical heterogeneity between them.

MAIN RESULTS

Seven randomized controlled trials (RCTs) were included; one of high quality, five of moderate quality, and one conference abstract. Second-line chemotherapy (irinotecan) showed moderate benefits in overall survival and progression-free survival over Best Supportive Care (BSC) and fluorouracil (5-FU). Fractionated administration has not proven to be more beneficial and is more toxic. Definitive results concerning the benefits and risks of oxaliplatin are pending publication.

AUTHORS' CONCLUSIONS

Second-line chemotherapy is effective in prolonging time to progression and survival in patients with advanced colorectal cancer. Further RCTs are needed to assess the optimal chemotherapy regimen.

Ex vivo programmed cell death and the prediction of response to chemotherapy

Since the earliest introduction of cytotoxic chemotherapy, investigators have pursued laboratory techniques designed to match patients to available drugs. Most of the work, published through the 1980s, reflected the prevailing view of cancer as a disease of dysregulated cell proliferation. Noteworthy, the description of apoptosis and programmed cell death, fundamental to our modern understanding of human tumor biology, did not occur until well after the heyday of in vitro chemosensitivity testing. By incorporating the modern tenets of carcinogenesis associated with perturbations in cell survival we can now re-examine laboratory assays of drug response in the context of drug-induced programmed cell death. Although there is interest in the use of genomic analyses for the prediction of chemotherapy response, the painful recognition that genotype does not equal phenotype will continue to limit broad application of these platforms. Biosystematics instructs that biological pathways rarely follow predicted routes. Efforts to force human biology to behave according to preconceived scientific dictates have proven costly and unsuccessful. Whole-cell experimental models with the capacity to evaluate all the operative mechanisms of cellular response to injury, acting in concert, provide valid tools for the study of human cancer. Educated by cellular behavior, we can expeditiously examine molecular processes of interest. This article briefly reviews the history of whole-cell experimental models of in vitro chemosensitivity testing then focuses on cell-death measures as the most robust predictors of clinical outcome in human cancer.

Short term culture of breast cancer tissues to study the activity of the anticancer drug taxol in an intact tumor environment

BACKGROUND

Sensitivity of breast tumors to anticancer drugs depends upon dynamic interactions between epithelial tumor cells and their microenvironment including stromal cells and extracellular matrix. To study drug-sensitivity within different compartments of an individual tumor ex vivo, culture models directly established from fresh tumor tissues are absolutely essential.

METHODS

We prepared 0.2 mm thick tissue slices from freshly excised tumor samples and cultivated them individually in the presence or absence of taxol for 4 days. To visualize viability, cell death, and expression of surface molecules in different compartments of non-fixed primary breast cancer tissues we established a method based on confocal imaging using mitochondria- and DNA-selective dyes and fluorescent-conjugated antibodies. Proliferation and apoptosis was assessed by immunohistochemistry in sections from paraffin-embedded slices. Overall viability was also analyzed in homogenized tissue slices by a combined ATP/DNA quantification assay.

RESULTS

We obtained a mean of 49 tissue slices from 22 breast cancer specimens allowing a wide range of experiments in each individual tumor. In our culture system, cells remained viable and proliferated for at least 4 days within their tissue environment. Viability of tissue slices decreased significantly in the presence of taxol in a dose-dependent manner. A three-color fluorescence viability assay enabled a rapid and authentic estimation of cell viability in the different tumor compartments within non-fixed tissue slices.

CONCLUSION

We describe a tissue culture method combined with a novel read out system for both tissue cultivation and rapid assessment of drug efficacy together with the simultaneous identification of different cell types within non-fixed breast cancer tissues. This method has potential significance for studying tumor responses to anticancer drugs in the complex environment of a primary cancer tissue.

New Hints on the pH-Driven Tautomeric Equilibria of the Topotecan Anticancer Drug in Aqueous Solutions from an Integrated Spectroscopic and Quantum-Mechanical Approach

The equilibria between the different forms of the topotecan anticancer drug have been studied at moderately acidic and physiological pH by an integrated computational tool rooted in the density functional theory and its time-dependent extension together with the polarizable continuum model. The results allow an unbiased selection between the different possible tautomeric forms and provide invaluable complements to experimental data. The ultraviolet-visible topotecan spectrum, recorded at moderately acidic pH, is accurately reproduced only by TD-DFT computations including solvent effects. Comparison of the experimental and calculated bands of the UV-vis spectrum at physiological pH indicates the presence of an equilibrium among different forms that is tuned by the microenvironment embedding the drug. The quantitative agreement between TD-DFT/PCM computations and experiments allows the identification of unequivocal spectroscopic signatures for different forms of topotecan.

Augmenting tumor sensitivity to topotecan by transient hypoxia

We examined how the effect of topotecan is modulated by transient hypoxia in three different tumor lines, Lewis lung carcinoma (LLC), U87 human glioblastoma and DMS273 human small cell lung cancer. Four groups of tumor bearing mice were treated with saline or a single dose of topotecan, immediately followed by 6-h or 72-h exposure to a hypoxic environment (10% O(2)) or normal air. Topotecan + hypoxia resulted in significantly greater suppression of tumor growth than normoxic topotecan or hypoxia alone. Correspondingly, the sensitivity of LLC cells to topotecan in a clonogenic survival assay was significantly higher under hypoxia. This effect of hypoxia was not a general phenomenon, since the tumor growth inhibitory effect of the alkylating agent cisplatin was not changed by hypoxic environment. In a parallel series of in vitro experiments, cell cultures were exposed to hypoxia (0.1% or 0.7% O(2)) in a hypoxic chamber or normoxia for 24 h. We found a dose-dependent downregulation of HIF-1alpha by topotecan (30-270 nM). The hypoxic upregulation of Glucose transporter-1 and VEGF secretion to the culture medium was inhibited by the addition of topotecan, while doses up to 270 nM had no effect on VEGF under normoxia. VEGF protein levels in tumors were also reduced by topotecan. These data show that the effect of topotecan is increased by transient hypoxia, and this may be a direct effect on the ability of cells to survive under hypoxia as well as an antiangiogenic effect, mediated through the HIF-1 inhibitory effect of topotecan.

Topotecan in the treatment of recurrent small cell lung cancer: an update

Small cell lung cancer (SCLC) is an aggressive malignancy with a high propensity for early regional and distant metastasis. Response rates to first-line chemotherapy are typically high, but short lived. The outlook for patients with recurrent SCLC is poor. A variety of single- and multi-agent chemotherapy regimens have met with limited success in patients with recurrent SCLC, and survival is generally measured in weeks. Until recently, further chemotherapy was not widely considered appropriate for patients with relapsed SCLC. The choice of chemotherapy at relapse is dependent on many factors, including type of and response to first-line therapy, the treatment-free interval, and the patient's performance status. Intravenous topotecan (Hycamtin; GlaxoSmithKline; Philadelphia, PA) has provided oncologists and patients in many countries with an effective and tolerable therapeutic option for recurrent SCLC. The clinical profile of topotecan was established in several phase II studies and confirmed in a randomized, phase III trial versus cyclophosphamide, doxorubicin (Adriamycin; Bedford Laboratories; Bedford, OH), and vincristine (Oncovin; Eli Lilly and Company; Indianapolis, IN)--CAV. In those studies, topotecan exhibited antitumor activity in both chemosensitive and refractory disease. Further, topotecan therapy is associated with significant symptom palliation in this patient population. Because the toxicity profile of topotecan is predictable, generally manageable, and noncumulative, the agent also has potential utility in patients with a poor prognosis and/or a poor performance status. Alternative dosing regimens (lower dose, weekly) and the introduction of an oral formulation may expand the use of topotecan as a single agent and in combination therapy in the second- and first-line treatment of this disease.

Topotecan in the first-line treatment of small cell lung cancer

Small cell lung cancer (SCLC) is generally sensitive to first-line chemotherapy, but limited disease often recurs and extensive disease is rarely curable. The most common first-line therapy regimen is cisplatin (Platinol; Bristol-Myers Squibb; Princeton, NJ) plus etoposide (Etopophos; Bristol-Myers Squibb)--PE, which is associated with overall response rates >80% in patients with limited SCLC. Although it is associated with median survival times of approximately 18-20 months for limited disease, PE yields median survival times of only approximately 8-12 months in patients with extensive disease, and symptom palliation becomes the primary therapeutic goal. The toxicities of PE may undermine quality of life and leave patients more susceptible to adverse events during subsequent therapies. Topotecan (HYCAMTIN; GlaxoSmithKline; Philadelphia, PA), an established treatment for recurrent SCLC, is being investigated in the first-line setting because of its novel mechanism of action; predictable, noncumulative, and manageable toxicities; and potential synergy with other active agents. Several recent phase II trials have generated promising results for topotecan-based combination regimens, including topotecan/paclitaxel (TAXOL; Bristol-Myers Squibb) (overall response rates 45%-100%), topotecan/etoposide (overall response, 95%), and topotecan, paclitaxel, and platinum agent triplets (overall response rates 51%-93%). The most frequent serious toxicity associated with these regimens was reversible and noncumulative neutropenia, which was generally manageable with supportive care. Additional clinical trials to investigate topotecan-based combination regimens and confirm their role in the first-line treatment of SCLC are under way.