In vitro cross-resistance and collateral sensitivity in seven resistant small-cell lung cancer cell lines: preclinical identification of suitable drug partners to taxotere, taxol, topotecan and gemcitabin

Phase II study of IRInotecan treatment after COmbined chemo-immunotherapy for extensive-stage small cell lung cancer: Protocol of IRICO study

INTRODUCTION

Combined treatment using anti-programmed death-ligand 1 antibody (anti-PD-L1) and platinum-etoposide is the current standard first-line treatment for patients with extensive-stage (ES) small cell lung cancer (SCLC). However, the best treatment for relapsed ES-SCLC after the first-line treatment remains unclear. There are some approved chemotherapeutic agents that can be used against ES-SCLC, and treatment with irinotecan is well established as both a monotherapy and a combined therapy, in combination with platinum. Therefore, we conduct a phase II study with irinotecan in the second- or later-line setting for patients with ES-SCLC who have been previously treated with combined treatment.

METHODS

Our study will enroll total 30 patients who are diagnosed with ES-SCLC and have experienced disease progression after the combined treatment. Patients will receive irinotecan on days 1, 8, and 15, which will be repeated every 4 weeks. Doses of irinotecan (100/80/60 mg/m2 ) will be determined according to the type of UGT1A1 gene polymorphism, and the treatment will be discontinued following disease progression, intolerance, withdrawal of patient consent, and based on the investigator's decision. The primary endpoint of the study is the response rate, and the secondary endpoints are overall survival, progression-free survival, and safety.

DISCUSSION

Since the present first-line treatment has been changed to the combined treatment, the second- or later-line treatment should be re-evaluated for patients with relapsed SCLC. Irinotecan is a major chemotherapeutic agent used for SCLC. This study demonstrates and re-evaluates the clinical benefits of irinotecan after combined treatment with anti-PD-L1 and platinum-etoposide for patients with ES-SCLC.

REGISTRATION DETAILS

This study was registered in the Japan Registry of Clinical Trials (no. jRCT s071210090) on November 4, 2021.

Functionalized Lineage Tracing Can Enable the Development of Homogenization-Based Therapeutic Strategies in Cancer

The therapeutic landscape across many cancers has dramatically improved since the introduction of potent targeted agents and immunotherapy. Nonetheless, success of these approaches is too often challenged by the emergence of therapeutic resistance, fueled by intratumoral heterogeneity and the immense evolutionary capacity inherent to cancers. To date, therapeutic strategies have attempted to outpace the evolutionary tempo of cancer but frequently fail, resulting in lack of tumor response and/or relapse. This realization motivates the development of novel therapeutic approaches which constrain evolutionary capacity by reducing the degree of intratumoral heterogeneity prior to treatment. Systematic development of such approaches first requires the ability to comprehensively characterize heterogeneous populations over the course of a perturbation, such as cancer treatment. Within this context, recent advances in functionalized lineage tracing approaches now afford the opportunity to efficiently measure multimodal features of clones within a tumor at single cell resolution, enabling the linkage of these features to clonal fitness over the course of tumor progression and treatment. Collectively, these measurements provide insights into the dynamic and heterogeneous nature of tumors and can thus guide the design of homogenization strategies which aim to funnel heterogeneous cancer cells into known, targetable phenotypic states. We anticipate the development of homogenization therapeutic strategies to better allow for cancer eradication and improved clinical outcomes.

The population genetics of collateral resistance and sensitivity

Resistance mutations against one drug can elicit collateral sensitivity against other drugs. Multi-drug treatments exploiting such trade-offs can help slow down the evolution of resistance. However, if mutations with diverse collateral effects are available, a treated population may evolve either collateral sensitivity or collateral resistance. How to design treatments robust to such uncertainty is unclear. We show that many resistance mutations in Escherichia coli against various antibiotics indeed have diverse collateral effects. We propose to characterize such diversity with a joint distribution of fitness effects (JDFE) and develop a theory for describing and predicting collateral evolution based on simple statistics of the JDFE. We show how to robustly rank drug pairs to minimize the risk of collateral resistance and how to estimate JDFEs. In addition to practical applications, these results have implications for our understanding of evolution in variable environments.

Drugs known as antibiotics are the main treatment for most serious infections caused by bacteria. However, many bacteria are acquiring genetic mutations that make them resistant to the effects of one or more types of antibiotics, making them harder to eliminate.

One way to tackle drug-resistant bacteria is to develop new types of antibiotics; however, in recent years, the rate at which new antibiotics have become available has been dwindling. Using two or more existing drugs, one after another, can also be an effective way to eliminate resistant bacteria. The success of any such ‘multi-drug’ treatment lies in being able to predict whether mutations that make the bacteria resistant to one drug simultaneously make it sensitive to another, a phenomenon known as collateral sensitivity.

Different resistance mutations may have different collateral effects: some may increase the bacteria’s sensitivity to the second drug, while others might make the bacteria more resistant. However, it is currently unclear how to design robust multi-drug treatments that take this diversity of collateral effects into account.

Here, Ardell and Kryazhimskiy used a concept called JDFE (short for the joint distribution of fitness effects) to describe the diversity of collateral effects in a population of bacteria exposed to a single drug. This information was then used to mathematically model how collateral effects evolved in the population over time.

Ardell and Kryazhimskiy showed that this approach can predict how likely a population is to become collaterally sensitive or collaterally resistant to a second antibiotic. Drug pairs can then be ranked according to the risk of collateral resistance emerging, so long as information on the variety of resistance mutations available to the bacteria are included in the model.

Each year, more than 700,000 people die from infections caused by bacteria that are resistant to one or more antibiotics. The findings of Ardell and Kryazhimskiy may eventually help clinicians design multi-drug treatments that effectively eliminate bacterial infections and help to prevent more bacteria from evolving resistance to antibiotics. However, to achieve this goal, more research is needed to fully understand the range collateral effects caused by resistance mutations.

Multifunctional nanoplatforms co-delivering combinatorial dual-drug for eliminating cancer multidrug resistance

Clinically, the primary cause of chemotherapy failure belongs to the occurrence of cancer multidrug resistance (MDR), which directly leads to the recurrence and metastasis of cancer along with high mortality. More and more attention has been paid to multifunctional nanoplatform-based dual-therapeutic combination to eliminate resistant cancers. In addition to helping both cargoes improve hydrophobicity and pharmacokinetic properties, increase bioavailability, release on demand and enhance therapeutic efficacy with low toxic effects, these smart co-delivery nanocarriers can even overcome drug resistance. Here, this review will not only present different types of co-delivery nanocarriers, but also summarize targeted and stimuli-responsive combination nanomedicines. Furthermore, we will focus on the recent progress in the co-delivery of dual-drug using such intelligent nanocarriers for surmounting cancer MDR. Whereas it remains to be seriously considered that there are some knotty issues in the fight against MDR of cancers via using co-delivery nanoplatforms, including limited intratumoral retention, the possible changes of combinatorial ratio under complex biological environments, drug release sequence from the nanocarriers, and subsequent free-drug resistance after detachment from the nanocarriers. It is hoped that, with the advantage of continuously developing nanomaterials, two personalized therapeutic agents in combination can be better exploited to achieve the goal of cooperatively combating cancer MDR, thus advancing the time to clinical transformation.

Functional Genomics Approaches to Elucidate Vulnerabilities of Intrinsic and Acquired Chemotherapy Resistance

Drug resistance is a commonly unavoidable consequence of cancer treatment that results in therapy failure and disease relapse. Intrinsic (pre-existing) or acquired resistance mechanisms can be drug-specific or be applicable to multiple drugs, resulting in multidrug resistance. The presence of drug resistance is, however, tightly coupled to changes in cellular homeostasis, which can lead to resistance-coupled vulnerabilities. Unbiased gene perturbations through RNAi and CRISPR technologies are invaluable tools to establish genotype-to-phenotype relationships at the genome scale. Moreover, their application to cancer cell lines can uncover new vulnerabilities that are associated with resistance mechanisms. Here, we discuss targeted and unbiased RNAi and CRISPR efforts in the discovery of drug resistance mechanisms by focusing on first-in-line chemotherapy and their enforced vulnerabilities, and we present a view forward on which measures should be taken to accelerate their clinical translation.

Prior acquired resistance to paclitaxel relays diverse EGFR-targeted therapy persistence mechanisms

Secondary drug resistance stems from dynamic clonal evolution during the development of a prior primary resistance. This collateral type of resistance is often a characteristic of cancer recurrence. Yet, mechanisms that drive this collateral resistance and their drug-specific trajectories are still poorly understood. Using resistance selection and small-scale pharmacological screens, we find that cancer cells with primary acquired resistance to the microtubule-stabilizing drug paclitaxel often develop tolerance to epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs), leading to formation of more stable resistant cell populations. We show that paclitaxel-resistant cancer cells follow distinct selection paths under EGFR-TKIs by enriching the stemness program, developing a highly glycolytic adaptive stress response, and rewiring an apoptosis control pathway. Collectively, our work demonstrates the alterations in cellular state stemming from paclitaxel failure that result in collateral resistance to EGFR-TKIs and points to new exploitable vulnerabilities during resistance evolution in the second-line treatment setting.

The Promising Connection Between Data Science and Evolutionary Theory in Oncology

Theoretical and empirical work over the past several decades suggests that oncogenesis and disease progression represents an evolutionary story. Despite this knowledge, current anti-resistance strategies to drugs are often managed through treating cancers as independent biological agents divorced from human activity. Yet once drug resistance to cancer treatment is understood as a product of artificial or anthropogenic rather than unconscious selection, oncologists could improve outcomes for their patients by consulting evolutionary studies of oncology prior to clinical trial and treatment plan design. In the setting of multiple cancer types, for example, a machine learning algorithm can predict the genetic changes known to be related to drug resistance. In this way, a unity between technology and theory might have practical clinical implications—and may pave the way for a new paradigm shift in medicine.

Irinotecan, topotecan, paclitaxel or docetaxel for second-line treatment of small cell lung cancer: a single-center retrospective study of efficiency comparation and prognosis analysis

Background

The main aim of this study was to evaluate the efficiency of second-line chemotherapy irinotecan (CPT-11), topotecan (TPT), paclitaxel (PTX) and docetaxel (DTX) in small cell lung cancer (SCLC) patients who have failure to the first-line standard treatment. The secondary aim was to evaluate the independent prognostic factors of patients who received a second line treatment.

Methods

Retrospective analysis of 116 patients who received second-line chemotherapy. Patients were divided into 4 groups according to the therapy they were treated with, which were CPT-11, TPT, PTX and DTX. Progress free survival (PFS), overall survival (OS), objective response rate (ORR) and disease control rate (DCR) were evaluated for each group. Patients' data of clinical character and blood index were collected, and the prognostic factors were assessed both at univariate and multivariate levels.

Results

Patients treated with CPT-11 achieved the best median PFS and OS of 91 and 595 days, while the median PFS of TPT, PTX and DTX were 74.5, 81 and 50 days respectively. The median OS of them were 154, 168.5 and 184 days respectively. The survival curves of OS were significantly different (P=0.0069). The reaction to second-line therapy is positively correlate to the reaction to first-line therapy (P=0.012). In the multivariate analysis, treatment free interval (TFI) <90 days, lactate dehydrogenase (LDH) ≥225 U/L, neutrophil-to-lymphocyte ratio (NLR) ≥3.5 were identified as independent risk factors for poor prognosis in second-line SCLC patients.

Conclusions

Second-line chemotherapy with TPT in SCLC patients may provide better overall survival benefits. TFI <90 days, LDH ≥225 U/L and NLR ≥3.5 are independent risk factors for second-line SCLC patients.

Limited Evolutionary Conservation of the Phenotypic Effects of Antibiotic Resistance Mutations

Multidrug-resistant clinical isolates are common in certain pathogens, but rare in others. This pattern may be due to the fact that mutations shaping resistance have species-specific effects. To investigate this issue, we transferred a range of resistance-conferring mutations and a full resistance gene into Escherichia coli and closely related bacteria. We found that resistance mutations in one bacterial species frequently provide no resistance, in fact even yielding drug hypersensitivity in close relatives. In depth analysis of a key gene involved in aminoglycoside resistance (trkH) indicated that preexisting mutations in other genes-intergenic epistasis-underlie such extreme differences in mutational effects between species. Finally, reconstruction of adaptive landscapes under multiple antibiotic stresses revealed that mutations frequently provide multidrug resistance or elevated drug susceptibility (i.e., collateral sensitivity) only with certain combinations of other resistance mutations. We conclude that resistance and collateral sensitivity are contingent upon the genetic makeup of the bacterial population, and such contingency could shape the long-term fate of resistant bacteria. These results underlie the importance of species-specific treatment strategies.

Combination immunotherapy with IL-4 Pseudomonas exotoxin and IFN-α and IFN-γ mediate antitumor effects in vitro and in a mouse model of human ovarian cancer

AIM

We have shown that IL-4 fused to Pseudomonas exotoxin (IL-4-PE) is cytotoxic to ovarian cancer cell lines. The antineoplastic properties of IFN-α, IFN-γ and IL-4-PE have been studied and showed some promise in the clinical trials. Here, we investigated whether the combination of IL-4-PE, IFN-α and IFN-γ will result in increased ovarian cancer cell death in vitro and in vivo.

MATERIALS & METHODS

Ovarian cancer cells were tested in vitro to analyze the cytotoxic effects of IL-4-PE, IFN-α and IFN-γ, and the combination of all three. Tumor-bearing xenograft mice were treated with the combination of IL-4-PE, IFN-α and IFN-γ to monitor their overall survival. The JAK/STAT phosphorylation signaling pathways were studied to delineate the mechanism of synergistic antitumor activity.

RESULTS

The combination of IL-4-PE with IFN-α and IFN-γ resulted in increased ovarian cancer cell death in vitro and in vivo. Mechanistically, the synergistic antitumor effect was dependent on interferon signaling, but not IL-4-PE signaling as determined by signaling specific chemical inhibitors. The combination therapy induced the activation of critical mediators of apoptosis.

CONCLUSION

The combination of IL-4-PE with interferons increased overall survival of mice with human ovarian cancer xenograft. These data suggest that this novel combination could provide a unique approach to treating ovarian cancer.

Induction of apoptosis and suppression of tumor growth by Nur77-derived Bcl-2 converting peptide in chemoresistant lung cancer cells

Resistance to chemotherapy is a major cause of treatment failure and poor overall survival in patients with lung cancer. Identification of molecular targets present in resistant cancer cells is essential for addressing therapeutic resistance and prolonging lung cancer patient survival. Members of the B-cell lymphoma 2 (Bcl-2) family of proteins are associated with chemotherapeutic resistance. In this study, we found that pro-survival protein Bcl-2 is upregulated in paclitaxel resistant cells, potentially contributing to chemotherapy resistance. To exploit the increase in Bcl-2 expression for targeting therapy resistance, we investigated the effects of a peptide derived from the nuclear receptor Nur77 that converts Bcl-2 from an anti-apoptotic protein to a pro-apoptotic protein. The Nur77 derived peptide preferentially induced apoptosis in paclitaxel-resistant cancer cells with high expression of Bcl-2. This peptide also induced apoptosis of multidrug resistant H69AR lung cancer cells that express Bcl-2 and inhibited their growth in 3D spheroids. The Nur77 peptide strongly suppressed the growth of paclitaxel-resistant lung cancer cells in a zebrafish xenograft tumor model. Taken together, our data supports a new strategy for treating lung cancers that acquire resistance to chemotherapy through overexpression of Bcl-2.

New insights from the widening homogeneity perspective to target intratumor heterogeneity

Precision medicine has shed new light on the treatment of heterogeneous cancer patients. However, intratumor heterogeneity strongly constrains the clinical benefit of precision medicine. Thus, rethinking therapeutic strategies from a different facet within the precision medicine framework will not only diversify clinical interventions, but also provide an avenue for precision medicine. Here, we explore the current approaches for targeting intratumor heterogeneity and their limitations. Furthermore, we propose a theoretical strategy with a "homogenization" feature based on iatrogenic evolutionary selection to target intratumor heterogeneity.

From Chemotherapy to Combined Targeted Therapeutics: In Vitro and in Vivo Models to Decipher Intra-tumor Heterogeneity

Recent advances in next-generation sequencing and other omics technologies capable to map cell fate provide increasing evidence on the crucial role of intra-tumor heterogeneity (ITH) for cancer progression. The different facets of ITH, from genomic to microenvironmental heterogeneity and the hierarchical cellular architecture originating from the cancer stem cell compartment, contribute to the range of tumor phenotypes. Decoding these complex data resulting from the analysis of tumor tissue complexity poses a challenge for developing novel therapeutic strategies that can counteract tumor evolution and cellular plasticity. To achieve this aim, the development of in vitro and in vivo cancer models that resemble the complexity of ITH is crucial in understanding the interplay of cells and their (micro)environment and, consequently, in testing the efficacy of new targeted treatments and novel strategies of tailoring combinations of treatments to the individual composition of the tumor. This challenging approach may be an important cornerstone in overcoming the development of pharmaco-resistances during multiple lines of treatment. In this paper, we report the latest advances in patient-derived 3D (PD3D) cell cultures and patient-derived tumor xenografts (PDX) as in vitro and in vivo models that can retain the genetic and phenotypic heterogeneity of the tumor tissue.

Inhibiting DNA Polymerases as a Therapeutic Intervention against Cancer

Inhibiting DNA synthesis is an important therapeutic strategy that is widely used to treat a number of hyperproliferative diseases including viral infections, autoimmune disorders, and cancer. This chapter describes two major categories of therapeutic agents used to inhibit DNA synthesis. The first category includes purine and pyrmidine nucleoside analogs that directly inhibit DNA polymerase activity. The second category includes DNA damaging agents including cisplatin and chlorambucil that modify the composition and structure of the nucleic acid substrate to indirectly inhibit DNA synthesis. Special emphasis is placed on describing the molecular mechanisms of these inhibitory effects against chromosomal and mitochondrial DNA polymerases. Discussions are also provided on the mechanisms associated with resistance to these therapeutic agents. A primary focus is toward understanding the roles of specialized DNA polymerases that by-pass DNA lesions produced by DNA damaging agents. Finally, a section is provided that describes emerging areas in developing new therapeutic strategies targeting specialized DNA polymerases.

The combination of A-966492 and Topotecan for effective radiosensitization on glioblastoma spheroids

Radiotherapy is one of the modalities in the treatment of glioblastoma patients, but glioma tumors are resistant to radiation and also chemotherapy drugs. Thus, researchers are investigating drugs which have radiosensitization capabilities in order to improve radiotherapy. PARP enzymes and topoisomerase I enzymes have a critical role in repairing DNA damage in tumor cells. Thus, inhibiting activity of these enzymes helps stop DNA damage repair and increase DSB lethal damages. In the current study, we investigated the combination of TPT as a topoisomerase I inhibitor, and A-966492 as a novel PARP inhibitor for further radiosensitization. U87MG cells (a human glioblastoma cell line) were cultured in Poly-Hema coated flasks to reach 300 μm-diameter spheroids. Treatments were accomplished by using non-toxic concentrations of A-966492 and Topotecan. The surviving fraction of treated cells was determined by clonogenic assay after treatment with drugs and 6 MV X-ray. The γ-H2AX expression was measured by an immunofluorescence staining method to examine the influence of A-966492, TPT and radiation on the induction of double stranded DNA breaks. Treatments using the A-966492 drug were conducted in concentration of 1 μM. Combining A-966492 and TPT with radiation yielded enhanced cell killing, as demonstrated by a sensitizer enhancement ratio at 50% survival (SER₅₀) 1.39 and 1.16 respectively. Radio- and chemo-sensitization was further enhanced when A-966492 was combined with both X-ray and TPT, with SER₅₀ of 1.53. Also γ-H2AX expression was higher in the group treated with a combination of drugs and radiation. A-966492 is an effective PARP inhibitor and has significant radio-sensitivity on U87MG spheroids. By accumulating cells in the S phase and by inhibiting the DNA damage repair, TPT enhanced radio-sensitivity. A-966492 combined with TPT as a topoisomerase I inhibitor had additive radio-sensitizing effects. As a result, applying PARP and topoisomerase I inhibitors can be a suitable strategy for improving radiotherapy in clinics.

Clonal Heterogeneity and Tumor Evolution: Past, Present, and the Future

Intratumor heterogeneity, which fosters tumor evolution, is a key challenge in cancer medicine. Here, we review data and technologies that have revealed intra-tumor heterogeneity across cancer types and the dynamics, constraints, and contingencies inherent to tumor evolution. We emphasize the importance of macro-evolutionary leaps, often involving large-scale chromosomal alterations, in driving tumor evolution and metastasis and consider the role of the tumor microenvironment in engendering heterogeneity and drug resistance. We suggest that bold approaches to drug development, harnessing the adaptive properties of the immune-microenvironment while limiting those of the tumor, combined with advances in clinical trial-design, will improve patient outcome.

Exploiting Temporal Collateral Sensitivity in Tumor Clonal Evolution

The prevailing approach to addressing secondary drug resistance in cancer focuses on treating the resistance mechanisms at relapse. However, the dynamic nature of clonal evolution, along with potential fitness costs and cost compensations, may present exploitable vulnerabilities-a notion that we term "temporal collateral sensitivity." Using a combined pharmacological screen and drug resistance selection approach in a murine model of Ph(+) acute lymphoblastic leukemia, we indeed find that temporal and/or persistent collateral sensitivity to non-classical BCR-ABL1 drugs arises in emergent tumor subpopulations during the evolution of resistance toward initial treatment with BCR-ABL1-targeted inhibitors. We determined the sensitization mechanism via genotypic, phenotypic, signaling, and binding measurements in combination with computational models and demonstrated significant overall survival extension in mice. Additional stochastic mathematical models and small-molecule screens extended our insights, indicating the value of focusing on evolutionary trajectories and pharmacological profiles to identify new strategies to treat dynamic tumor vulnerabilities.

The role of ABC transporters in ovarian cancer progression and chemoresistance

Over 80% of ovarian cancer patients develop chemoresistance which results in a lethal course of the disease. A well-established cause of chemoresistance involves the family of ATP-binding cassette transporters, or ABC transporters that transport a wide range of substrates including metabolic products, nutrients, lipids, and drugs across extra- and intra-cellular membranes. Expressions of various ABC transporters, shown to reduce the intracellular accumulation of chemotherapy drugs, are increased following chemotherapy and impact on ovarian cancer survival. Although clinical trials to date using ABC transporter inhibitors have been disappointing, ABC transporter inhibition remains an attractive potential adjuvant to chemotherapy. A greater understanding of their physiological functions and role in ovarian cancer chemoresistance will be important for the development of more effective targeted therapies. This article will review the role of the ABC transporter family in ovarian cancer progression and chemoresistance as well as the clinical attempts used to date to reverse chemoresistance.

Combination of paclitaxel thermal gel depot with temozolomide and radiotherapy significantly prolongs survival in an experimental rodent glioma model

OncoGel™ incorporates paclitaxel, a mitotic inhibitor, into ReGel™, a thermosensitive gel depot system to provide local delivery, enhance efficacy and limit systemic toxicity. In previous studies the alkylating agent temozolomide (TMZ) incorporated into a polymer, pCPP:SA, also for local delivery, and OncoGel were individually shown to increase efficacy in a rat glioma model. We investigated the effects of OncoGel with oral TMZ or locally delivered TMZ polymer, with and without radiotherapy (XRT) in rats with intracranial gliosarcoma. Eighty-nine animals were intracranially implanted with a 9L gliosarcoma tumor and divided into 12 groups that received various combinations of 4 treatment options; OncoGel 6.3 mg/ml (Day 0), 20 Gy XRT (Day 5), 50 % TMZ-pCPP:SA (Day 5), or oral TMZ (50 mg/kg, qd, Days 5-9). Animals were followed for survival for 120 days. Median survival for untreated controls, XRT alone or oral TMZ alone was 15, 19 and 28 days, respectively. OncoGel 6.3 or TMZ polymer alone extended median survival to 33 and 35 days, respectively (p = 0.0005; p < 0.0001, vs. untreated controls) with 50 % living greater than 120 days (LTS) in both groups. Oral TMZ/XRT extended median survival to 36 days (p = 0.0002), with no LTS. The group that received OncoGel and Oral TMZ did not reach median survival with 57 % LTS (p = 0.0002). All other combination groups [OncoGel/XRT], [TMZ polymer/XRT], [OncoGel/TMZ polymer], [OncoGel/TMZ polymer/XRT], and [OncoGel/oral TMZ/XRT] yielded greater than 50 % LTS (p < 0.0001 for each combination as compared to controls), therefore median survival was not reached. OncoGel/TMZ polymer and OncoGel/oral TMZ/XRT had 100 % LTS (p < 0.0001 and p = 0.0001 vs. oral TMZ/XRT, respectively). These results indicate that OncoGel given locally with oral or locally delivered TMZ and/or XRT significantly increased the number of LTS and improved median survival compared to oral TMZ and XRT given alone or in combination in a rodent intracranial gliosarcoma model.

Single agent- and combination treatment with two targeted suicide gene therapy systems is effective in chemoresistant small cell lung cancer cells

BACKGROUND

Transcriptional targeted suicide gene (SG) therapy driven by the insulinoma-associated 1 (INSM1) promoter makes it possible to target suicide toxin production and cytotoxicity exclusively to small cell lung cancer (SCLC) cells and tumors. It remains to be determined whether acquired chemoresistance, as observed in the majority of SCLC patients, desensitizes SCLC cells to INSM1 promoter-driven SG therapy.

METHODS

A panel of SCLC cell lines resistant to clinically relevant chemotherapeutics was characterized regarding the expression of proteins involved in response to chemotherapy and regarding INSM1 promoter activity. Sensitivity towards INSM1 promoter-driven SG therapy was tested using different systems: Yeast cytosine deaminase-uracil phosphoribosyl transferase (YCD-YUPRT) in combination with the prodrug 5-fluorocytosine (5-FC) or Escherichia coli nitroreductase (NTR) together with the bromomustard prodrug SN27686.

RESULTS

The chemoresistant cell lines displayed heterogeneous expression profiles of molecules involved in multidrug resistance, apoptosis and survival pathways. Despite this, the INSM1 promoter activity was found to be unchanged or increased in SCLC chemoresistant cells and xenografts compared to chemosensitive variants. INSM1 promoter-driven SG therapy with YCD-YUPRT/5-FC or NTR/SN27686, was found to induce high levels of cytotoxicity in both chemosensitive and chemoresistant SCLC cells. Moreover, the combination of INSM1 promoter-driven YCD-YUPRT/5-FC therapy and chemotherapy, as well as the combination of INSM1 promoter-driven YCD-YUPRT/5-FC and NTR/SN27686 therapy, was observed to be superior to single agent therapy in chemoresistant SCLC cells.

CONCLUSIONS

Collectively, the present study demonstrates that targeted SG therapy is a potent therapeutic approach for chemoresistant SCLC patients, with the highest efficacy achieved when applied as combination SG therapy or in combination with standard chemotherapy.

Distinct genetic alterations occur in ovarian tumor cells selected for combined resistance to carboplatin and docetaxel

BACKGROUND

Current protocols for the treatment of ovarian cancer include combination chemotherapy with a platinating agent and a taxane. However, many patients experience relapse of their cancer and the development of drug resistance is not uncommon, making successful second line therapy difficult to achieve. The objective of this study was to develop and characterize a cell line resistant to both carboplatin and docetaxel (dual drug resistant ovarian cell line) and to compare this cell line to cells resistant to either carboplatin or docetaxel.

METHODS

The A2780 epithelial endometrioid ovarian cancer cell line was used to select for isogenic carboplatin, docetaxel and dual drug resistant cell lines. A selection method of gradually increasing drug doses was implemented to avoid clonal selection. Resistance was confirmed using a clonogenic assay. Changes in gene expression associated with the development of drug resistance were determined by microarray analysis. Changes in the expression of selected genes were validated by Quantitative Real-Time Polymerase Chain Reaction (QPCR) and immunoblotting.

RESULTS

Three isogenic cell lines were developed and resistance to each drug or the combination of drugs was confirmed. Development of resistance was accompanied by a reduced growth rate. The microarray and QPCR analyses showed that unique changes in gene expression occurred in the dual drug resistant cell line and that genes known to be involved in resistance could be identified in all cell lines.

CONCLUSIONS

Ovarian tumor cells can acquire resistance to both carboplatin and docetaxel when selected in the presence of both agents. Distinct changes in gene expression occur in the dual resistant cell line indicating that dual resistance is not a simple combination of the changes observed in cell lines exhibiting single agent resistance.

Gemcitabine and paclitaxel combination as second-line chemotherapy in patients with small-cell lung cancer: a phase II study

BACKGROUND

Although small-cell lung cancer is a chemosensitive malignancy, most patients rapidly relapse. Results of second-line treatment are generally poor. We conducted a phase II study to evaluate the activity and toxicity of a combination of gemcitabine and paclitaxel as second-line chemotherapy.

PATIENTS AND METHODS

Eligible patients were refractory or relapsed small-cell lung cancer, with an Eastern Cooperative Oncology Group performance status of 0-2 and measurable disease. Paclitaxel was administered at 135 mg/m(2) days 1 and 8 immediately followed by gemcitabine at 1000 mg/m(2) every 3 weeks up to 6 courses. Restaging of disease was scheduled every 3 courses.

RESULTS

Forty-one patients were enrolled. The median age was 65 years. Nineteen patients were considered refractory (progressive disease during or within 90 days from completion of first-line treatment), whereas 22 patients were chemotherapy sensitive. A total of 135 courses was administered (range, 1-6; median, 3). Nine patients achieved a partial remission (partial response, 22%), and 10 patients had stable disease (24%), with a disease control rate (partial response + stable disease) of 46%: in 12 (55%) of 22 patients who were sensitive and in 7 (37%) of 19 patients with refractory disease, respectively. All partial responses but one were observed in the sensitive group. The median duration of response was 5 months. The most-frequent severe toxicities were neutropenia grade 3-4 and neurologic grade 3 in 24% and 7% of delivered courses, respectively.

CONCLUSIONS

The combination of gemcitabine and paclitaxel investigated in our study achieved a high disease control rate, but the schedule we adopted appeared to be quite toxic.

Phase II study of gemcitabine and docetaxel in recurrent platinum resistant ovarian cancer

To evaluate the activity of gemcitabine and docetaxel in patients with recurrent ovarian cancer.

METHODS

Patients with platinum-resistant disease and prior treatment with paclitaxel received treatment with docetaxel on day 1 and gemcitabine on days 1 and 8, repeated every three weeks.

RESULTS

Twenty patients, with a platinum-free interval of three months, were enrolled. Overall response rate was 25%. Treatment was associated with significant myelosuppression.

CONCLUSIONS

In chemotherapy-resistant patients, this regimen exhibited encouraging activity. Excessive myelosuppression led to early closure. This was prevented by administering docetaxel on day 8 (instead of day 1) and prophylactic use of G-CSF.

Association of multi-drug resistance gene polymorphisms with pancreatic cancer outcome

BACKGROUND

The purpose of this study was to identify single nucleotide polymorphisms (SNPs) of multidrug resistance genes that are associated with clinical outcome in patients with potentially resectable pancreatic adenocarcinoma who were treated with preoperative gemcitabine-based chemoradiotherapy at M. D. Anderson Cancer Center.

METHODS

We selected 8 SNPs of 7 drug resistance genes, including MDR1 (ABCB1), MRP1-5 (ABCC1-5), and BCRP (ABCG2), reported to be important in mediating drug resistance. Genotype was determined by the Taqman method. The associations of genotype with tumor response to therapy and overall survival (OS) were evaluated using log-rank test, Cox regression, and logistic regression models.

RESULTS

MRP5 A-2G AA genotype showed significant association with OS (log-rank P = .010). The hazard ratio (95% confidence interval) was 1.65 (1.11-2.45) after adjusting for clinical predictors. The MRP2 G40A GG genotype had a weak association with reduced OS (log-rank P = .097). A combined effect of the two genotypes on OS was observed. Patients with none of the adverse genotypes had a median survival time (MST) of 34.0 months, and those with 1-2 deleterious alleles had a significantly lower MST of 20.7 months (log-rank P = .006). MRP2 G40A GG genotype was also significantly associated with poor histological response to chemoradiotherapy (P = .028).

CONCLUSIONS

These observations suggest a potential role of polymorphic variants of drug resistance genes in predicting therapeutic efficacy and survival of patients with potentially resectable pancreatic cancer.

Tumor and host factors that may limit efficacy of chemotherapy in non-small cell and small cell lung cancer

While chemotherapy provides useful palliation, advanced lung cancer remains incurable since those tumors that are initially sensitive to therapy rapidly develop acquired resistance. Resistance may arise from impaired drug delivery, extracellular factors, decreased drug uptake into tumor cells, increased drug efflux, drug inactivation by detoxifying factors, decreased drug activation or binding to target, altered target, increased damage repair, tolerance of damage, decreased proapoptotic factors, increased antiapoptotic factors, or altered cell cycling or transcription factors. Factors for which there is now substantial clinical evidence of a link to small cell lung cancer (SCLC) resistance to chemotherapy include MRP (for platinum-based combination chemotherapy) and MDR1/P-gp (for non-platinum agents). SPECT MIBI and Tc-TF scanning appears to predict chemotherapy benefit in SCLC. In non-small cell lung cancer (NSCLC), the strongest clinical evidence is for taxane resistance with elevated expression or mutation of class III beta-tubulin (and possibly alpha tubulin), platinum resistance and expression of ERCC1 or BCRP, gemcitabine resistance and RRM1 expression, and resistance to several agents and COX-2 expression (although COX-2 inhibitors have had minimal impact on drug efficacy clinically). Tumors expressing high BRCA1 may have increased resistance to platinums but increased sensitivity to taxanes. Limited early clinical data suggest that chemotherapy resistance in NSCLC may also be increased with decreased expression of cyclin B1 or of Eg5, or with increased expression of ICAM, matrilysin, osteopontin, DDH, survivin, PCDGF, caveolin-1, p21WAF1/CIP1, or 14-3-3sigma, and that IGF-1R inhibitors may increase efficacy of chemotherapy, particularly in squamous cell carcinomas. Equivocal data (with some positive studies but other negative studies) suggest that NSCLC tumors with some EGFR mutations may have increased sensitivity to chemotherapy, while K-ras mutations and expression of GST-pi, RB or p27kip1 may possibly confer resistance. While limited clinical data suggest that p53 mutations are associated with resistance to platinum-based therapies in NSCLC, data on p53 IHC positivity are equivocal. To date, resistance-modulating strategies have generally not proven clinically useful in lung cancer, although small randomized trials suggest a modest benefit of verapamil and related agents in NSCLC.

Activity of topotecan given intravenously for 5 days every three weeks in patients with advanced non-small cell lung cancer pretreated with platinum and taxanes: a phase II study

Topotecan, a semi-synthetic camptothecin analogue with topoisomerase I interaction, has shown to be an active agent in the treatment of advanced refractory lung cancer. This paper describes the authors' experience with this drug when used as a single agent in patients (pts) with advanced non-small cell lung cancer (NSCLC) refractory to platinum- and taxane-containing chemotherapy regimens. Thirty-five patients with NSCLC refractory to previous chemotherapy and KI ≥ 60% were included in the study. Their characteristics are as follows: median age of 52 years (range 43-69) and Karnofsky PS of 70 (60-80); 27 were male and 8 were female. Twenty-one (60%) patients had adenocarcinoma; eleven (31.4%), squamous cell, and three (8.5%), undifferentiated carcinoma. There was a median of two disease sites and two prior chemotherapy regimens. Topotecan was administered at a dose of 1.25 mg/m(2) I.V. daily for 5 days, repeated every 21 days until disease progression, maximal response, or intolerable toxicity. After 73 cycles, patients received a median of 2 treatment cycles (1-9). All patients except one were considered evaluable for toxicity; eight episodes (24%) of nausea/vomiting and two episodes (6%) of grade 1-2 asthenia, respectively, were reported. Four (12%) patients developed grade 1-2 anemia and two (6%) subjects suffered grade 3 anemia. Seven (21%) patients had grade 1-2 neutropenia and one (3%) presented grade 5 neutropenia. In 33 patients evaluable for activity of the 35 subjects included in the study; one (2.8%) presented a partial response; nine (25.7%) had stable disease, and 23 (65.7%) exhibited disease progression. Median time to progression and overall survival were 54 (12-210) and 70 (12-324) days, respectively. Intravenous topotecan at that dose and administration schedule displays scant activity in terms of response rate in individuals with advanced NSCLC previously treated with platinum and taxanes. The role and usefulness of chemotherapy in this setting warrants further investigation and confirmation through comparative studies.

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.

Is resistance useless? Multidrug resistance and collateral sensitivity

When cancer cells develop resistance to chemotherapeutics, it is frequently conferred by the ATP-dependent efflux pump P-glycoprotein (MDR1, P-gp, ABCB1). P-gp can efflux a wide range of cancer drugs; its expression confers cross-resistance, termed "multidrug resistance" (MDR), to a wide range of drugs. Strategies to overcome this resistance have been actively sought for more than 30 years, yet clinical solutions do not exist. A less understood aspect of MDR is the hypersensitivity of resistant cancer cells to other drugs, a phenomenon known as "collateral sensitivity" (CS). This review highlights the extent of this effect for the first time, and discusses hypotheses (e.g. generation of reactive oxygen species) to account for the underlying generality of this phenomenon, and proposes exploitation of CS as a strategy to improve response to chemotherapy.

Inhibition of P-glycoprotein-mediated docetaxel efflux sensitizes ovarian cancer cells to concomitant docetaxel and SN-38 exposure

The first-line treatment of ovarian cancer is based on cytoreductive surgery and the use of anticancer drugs. The main disadvantage in the usage of anticancer drugs is the wide capacity of cancer cells to acquire a resistance to chemotherapeutic agents and therefore new treatment strategies have to be developed and tested. In this study, the responses of seven ovarian carcinoma cell lines to docetaxel and a camptothecin derivative, SN-38, were evaluated. We further studied the expression of P-glycoprotein (P-gp), the best described mechanism of drug resistance, in these cells and the effect of treatment with a specific P-gp inhibitor (PGP-4008). Simultaneous treatment with docetaxel and SN-38 (docetaxel+SN-38) had an antagonistic growth effect that was not dependent on the administration schedule. Both drugs alone or in combination induced G2M cell cycle arrest. Docetaxel was a more potent inducer of apoptosis than SN-38, but simultaneous treatment with docetaxel+SN-38 decreased the proportion of apoptotic cells to the same level observed after exposure to SN-38 alone. SN-38 increased P-gp expression in all cell lines. PGP-4008 enhanced docetaxel-mediated growth inhibition and apoptosis, but it did not have an effect when used simultaneously with SN-38. When cells were treated with docetaxel, SN-38, and PGP-4008 simultaneously, the growth was inhibited more efficiently and the proportion of apoptotic cells was higher than that without PGP-4008. Thus, treatment of ovarian cancer cells with docetaxel+SN-38 may have antagonistic effects. The simultaneous administration of a P-gp inhibitor may prevent docetaxel efflux, thereby sensitizing cells to docetaxel and other chemotherapeutic agents.

Pharmacogenomics of gemcitabine in non-small-cell lung cancer and other solid tumors

The validation of predictive biomarkers to tailor chemotherapy is a key issue in the development of effective treatment modalities against cancer. Examples of how genetics might affect drug response are offered by gemcitabine. A substantial number of potential biomarkers for sensitivity or resistance to gemcitabine have been proposed, including ribonucleotide reductase and cytidine deaminase polymorphisms, human equilibrative transporter-1 and ribonucleotide reductase gene-expression and AKT phosphorylation status. These markers displayed a significant relationship with disease response to the drug; however, their robustness needs to be evaluated within prospective studies. Moreover, recent trials of customized chemotherapy based on genetic markers have been carried out in non-small-cell lung cancer and promising pharmacogenetic determinants are gaining momentum, including BRCA1 and ERCC1. Hopefully, biomarkers to select patients most likely to respond to gemcitabine will be validated in the near future.

A systematic review of platinum and taxane resistance from bench to clinic: An inverse relationship

We undertook a systematic review of the pre-clinical and clinical literature for studies investigating the relationship between platinum and taxane resistance. Medline was searched for (1) cell models of acquired drug resistance reporting platinum and taxane sensitivities and (2) clinical trials of platinum or taxane salvage therapy in ovarian cancer. One hundred and thirty-seven models of acquired drug resistance were identified. 68.1% of cisplatin-resistant cells were sensitive to paclitaxel and 66.7% of paclitaxel-resistant cells were sensitive to cisplatin. A similar inverse pattern was observed for cisplatin vs. docetaxel, carboplatin vs. paclitaxel and carboplatin vs. docetaxel. These associations were independent of cancer type, agents used to develop resistance and reported mechanisms of resistance. Sixty-five eligible clinical trials of paclitaxel-based salvage after platinum therapy were identified. Studies of single agent paclitaxel in platinum-resistant ovarian cancer where patients had previously recieved paclitaxel had a pooled response rate of 35.3%, n=232, compared to 22% in paclitaxel naïve patients n=1918 (p<0.01, Chi-squared). Suggesting that pre-treatment with paclitaxel may improve the response of salvage paclitaxel therapy. The response rate to paclitaxel/platinum combination regimens in platinum-sensitive ovarian cancer was 79.5%, n=88 compared to 49.4%, n=85 for paclitaxel combined with other agents (p<0.001, Chi-squared), suggesting a positive interaction between taxanes and platinum. Therefore, the inverse relationship between platinum and taxanes resistance seen in cell models is mirrored in the clinical response to these agents in ovarian cancer. An understanding of the cellular and molecular mechanisms responsible would be valuable in predicting response to salvage chemotherapy and may identify new therapeutic targets.

Paclitaxel and gemcitabine vs. paclitaxel and pegylated liposomal doxorubicin in advanced non–nasopharyngeal head and neck cancer. An efficacy and cost analysis randomized study conducted by the Hellenic Cooperative Oncology Group

BACKGROUND

The prognosis of patients with recurrent and/or metastatic head and neck cancer (HNC) is poor. Median survival of these patients following chemotherapy is in the range of 6 to 9 months. In the present randomized phase III trial we compared two new combinations containing new drugs with proven activity in phase II studies with patients with HNC.

PATIENTS AND METHODS

From November 1999 until November 2004, 166 eligible patients with HNC were enrolled in the study. They were treated with paclitaxel 175 mg/m(2) on day 1 and gemcitabine 1000 mg/m(2) on days 1 and 8 every 3 weeks (group A, 85 patients) or with paclitaxel, as in group A, and pegylated liposomal doxorubicin 40 mg/m(2) on day 1 every 4 weeks (group B, 81 patients).

RESULTS

There was no significant difference in response rate (20% versus 29%, P = 0.21), time to disease progression (median; 4.4 months versus 6.0 months, P = 0.09) and survival (median; 8.6 months versus 11.05 months, P = 0.25). Both regimens were generally well tolerated. The most frequently reported side effect, apart from alopecia, was neutropenia. Overall, there was no significant difference in severe toxicity between the two treatment arms.

CONCLUSIONS

The present study could not demonstrate a survival benefit with either regimen. Both treatments were well tolerated. Randomized studies comparing each of the two regimens with standard chemotherapy are warranted.

Multidrug resistance in small cell lung cancer: expression of P-glycoprotein, multidrug resistance protein 1 and lung resistance protein in chemo-naive patients and in relapsed disease

The aim of this study was to investigate the expression of multidrug resistance-associated proteins in metastatic small cell lung cancer (SCLC) cells correlated to cisplatin/etoposide chemotherapy response and the level of those proteins in relapsed disease. Samples were obtained by transbronchial fine needle aspiration biopsy (TBNA) of enlarged mediastinal lymph nodes in 17 patients. After cytological confirmation of SCLC, cells were stained by a panel of mAbs against internal epitopes of P-gp (JSB-1), MRP1 (MRPr1), LRP (LRP-56) and cytokeratin (MNF116) and analyzed by flow cytometry. We observed a significant negative correlation for better response rate to chemotherapy with individual expression of P-gp (r=-0.93, P<0.0001; Pearson correlation) and MRP1 (r=-0.78, P=0.0002; Pearson correlation) in chemo-naive SCLC cells and a non-significant correlation for LRP expression. P-gp and MRP1 expression was markedly increased in metastatic cells in four out of five patients with relapsed disease (4-12 months after starting chemotherapy), in comparison to their chemo-naive values. In conclusion, the results suggest that P-gp and MRP1 might be associated with SCLC cell survival during metastasis and chemotherapy, and that overexpression of those transporters in relapsed disease could assist short-term chemotherapy efficiency.

Gemcitabine and paclitaxel in metastatic or recurrent squamous cell carcinoma of the head and neck: a phase I-II study

The purpose of this study was to determine the maximum tolerated dose, toxicity profile and anti-tumor activity of paclitaxel in combination with gemcitabine when administered to patients with unresectable locally recurrent or metastatic squamous cell carcinoma of the head and the neck (SCCHN). Twenty-seven patients were treated in a phase I-II study with gemcitabine at a dose of 800 mg/m on days 1 and 8, escalating to a dose of 1,000 mg/m, plus escalating doses of paclitaxel (100, 135 and 175 mg/m) on day 2. Treatment consisted of 6 cycles repeated every 3 weeks. The main toxicity was myelosuppression. Other toxicities were mild and manageable. Due to grade 4 neutropenia at higher doses the recommended dose level of the gemcitabine/paclitaxel combination was 1,000/135 mg/m. Four patients achieved a partial response and no patient had a complete remission, giving an overall response rate of 14.8%. The median time of survival was 24 weeks. We conclude that the combination of paclitaxel and gemcitabine is tolerated, but shows insufficient clinical activity in patients with recurrent and/or metastatic SCCHN to warrant further testing.

Docetaxel plus gemcitabine or docetaxel plus cisplatin in advanced pancreatic carcinoma: randomized phase II study 40984 of the European Organisation for Research and Treatment of Cancer Gastrointestinal Group

PURPOSE

To define the efficacy and toxicity of docetaxel plus gemcitabine or docetaxel plus cisplatin for advanced pancreatic carcinoma.

PATIENTS AND METHODS

Chemotherapy-naive patients with measurable disease and WHO performance status less than 2 were randomly assigned to receive 21-day cycles of gemcitabine 800 mg/m2 on days 1 and 8 plus docetaxel 85 mg/m2 on day 8 (arm A) or docetaxel 75 mg/m2 on day 1 plus cisplatin 75 mg/m2 on day 1 (arm B). Primary end points were tumor response and rate of febrile neutropenia grade.

RESULTS

Of 96 randomly assigned patients (49 patients in arm A and 47 patients in arm B), 70 patients were analyzed for response (36 in arm A and 34 in arm B) and 89 patients were analyzed for safety (45 in arm A and 44 in arm B). Confirmed responses were observed in 19.4% (95% CI, 8.2% to 36.0%) of patients in arm A and 23.5% (95% CI, 10.7% to 41.2%) in arm B. In arm A, the median progression-free survival (PFS) was 3.9 months (95% CI, 3.0 to 4.7 months), median survival was 7.4 months (95% CI, 5.6 to 11.0 months), and 1-year survival was 30%. In arm B, the median PFS was 2.8 months (95% CI, 2.6 to 4.6 months), median survival was 7.1 months (95% CI, 4.8 to 8.7 months), and 1-year survival was 16%. Febrile neutropenia occurred in 9% and 16% of patients in arms A and B, respectively.

CONCLUSION

Both regimens are well tolerated and show activity in advanced pancreatic carcinoma. The safety profile and survival analyses favor docetaxel plus gemcitabine for further evaluation.

Phase I clinical trial of topotecan and pegylated liposomal doxorubicin

BACKGROUND

The objective of this study was to determine the feasibility and maximum tolerated dose (MTD) of combination topotecan and pegylated liposomal doxorubicin (PLD) administered in 4- or 3-week cycles in patients with advanced or refractory solid tumors.

PATIENTS AND METHODS

Patients were treated with intravenous topotecan (0.75-1.25 mg/m2) for 3 days followed by PLD (25-40 mg/m2) on Day 4. The following dose combinations (topotecan/PLD, mg/m2) were explored: 0.75/40, 1.0/40, and 1.25/40 every 28 days; and 1.0/25 and 1.0/30 every 21 days.

RESULTS

Thirty-two patients were enrolled, and all had received prior chemotherapy. Most (84 percent) patients had ovarian cancer. A total of 157 cycles (median, 4 cycles; range, 1-19 cycles) of chemotherapy were administered. Dose-limiting toxicities were Grade 4 neutropenia and death at dose level 3 (1.25/40 mg/m2 every 28 days), and neutropenic fever, Grade 3 stomatitis, and Grade 3 peripheral neuropathy (all in one patient) at dose level 5 (1/30 mg/m2 every 21 days). Myelosuppression was the most common serious toxicity. Twenty-six patients were evaluable for response and 7 (27 percent) had partial responses. All responses were seen in patients with ovarian cancer.

CONCLUSIONS

This combination is feasible and well tolerated; encouraging activity was observed in heavily pretreated patients with ovarian cancer. The recommended regimens for a Phase II study are topotecan 1.0 mg/m2 on Days 1-3 followed by PLD 40 mg/m2 on Day 4 of a 28-day cycle, and topotecan 1.0 mg/m2 on Days 1-3 and PLD 30 mg/m2 on Day 4 of a 21-day cycle.

First-line therapy with gemcitabine and paclitaxel in locally, recurrent or metastatic breast cancer: a phase II study

Background

This phase II study evaluated the efficacy and safety of gemcitabine (G) plus paclitaxel (T) as first-line therapy in recurrent or metastatic breast cancer.

Methods

Patients with locally, recurrent or metastatic breast cancer and no prior chemotherapy for metastatic disease received G 1200 mg/m² on days 1 and 8, and T 175 mg/m² on day 1 (before G) every 21 days for a maximum of 10 cycles.

Results

Forty patients, 39 metastatic breast cancer and 1 locally-advanced disease, were enrolled. Their median age was 61.5 years, and 85% had a World Health Organization performance status (PS) of 0 or 1. Poor prognostic factors at baseline included visceral involvement (87.5%) and ≥2 metastatic sites (70%). Also, 27 (67.5%) patients had prior adjuvant chemotherapy, 25 of which had prior anthracyclines. A total of 220 cycles (median 6; range, 1–10) were administered. Of the 40 enrolled patients, 2 had complete response and 12 partial response, for an overall response rate of 35.0% for intent-to-treat population. Among 35 patients evaluable for efficacy the response rate was 40%. Additional 14 patients had stable disease, and 7 had progressive disease. The median duration of response was 12 months; median time to progression, 7.2 months; median survival, 25.7 months. Common grade 3/4 toxicities were neutropenia in 17 (42.5%) patients each, grade 3 leukopenia in 19 (47.5%), and grade 3 alopecia in 30 (75.0%) patients; 1 (2.5%) patient had grade 4 thrombocytopenia.

Conclusion

GT exhibited encouraging activity and tolerable toxicity as first-line therapy in metastatic breast cancer. Phase III trials for further evaluation are ongoing.

Gemcitabine monotherapy in recurrent ovarian cancer: from the bench to the clinic

Gemcitabine (2'2'-difluorodeoxycytidine [dFdC]) is a synthetic analog of deoxycytidine with two fluorine atoms at the 2' position of the carbohydrate. As a hydrophobic molecule, dFdC competes for intracellular access via membrane-associated nucleoside transporter proteins. Following intracellular transport, dFdC is phosphorylated sequentially by deoxycytidine kinase to gemcitabine triphosphate, which inhibits ribonucleotide metabolism, hinders DNA processing, and increases accumulation of intrastrand adducts and interstrand cross-links, thereby leading to a G1 block in the cell cycle. dFdC monotherapy has been extensively evaluated at doses of 800-1250 mg/m2. dFdC is generally well tolerated, with the most frequently occurring dose-limiting toxicities being hematologic, noncumulative, and easily managed by dose alteration. Several studies involving treatment of recurrent ovarian cancer patients with dFdC monotherapy, most of whom had platinum-resistant disease and/or prior exposure to paclitaxel, led to overall response rates of 14-22% and a median duration of response of 4.0-10.6 months. An additional one third of the participants experienced stable disease for an overall clinical benefit in approximately one half of the treated patients. Tumor cells with a multidrug resistance phenotype have increased sensitivity to dFdC (collateral sensitivity). As dFdC is unaffected by platinum resistance, and not susceptible to classic multidrug resistance, it could be particularly beneficial to administer following treatment with agents that induce multidrug resistance. Integration of dFdC with platinum and/or radiation should also be investigated.

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.

Changes in gene expression associated with stable drug and radiation resistance in small cell lung cancer cells are similar to those caused by a single X-ray dose

Small cell lung cancer (SCLC) initially responds well to chemotherapy and fractionated radiotherapy, but resistance to these treatments eventually develops in the vast majority of cases. To understand how resistance develops in the H69 SCLC cell line, we compared the changes in gene expression associated with 37.5 Gy fractionated X-ray treatment that produced the stable radiation- and drug-resistant H69/R38 cell subline to the changes associated with a single 4- or 8-Gy X-ray treatment. Gene expression was determined by suppression subtractive hybridization combined with Northern blot analysis and two-dimensional (2D) protein electrophoresis. Stable radiation and drug resistance was associated with coordinate changes in the expression of genes of the cytoskeleton, protein synthesis, cell cycle, redox/stress and metabolic pathways. The pattern of these changes was remarkably similar to the changes seen 24 h after a single X-ray treatment of the H69 cells but differed from the changes in expression associated with a single X-ray treatment of the resistant H69/ R38 cells. Stable radiation and drug resistance may be caused by the constitutive expression of those genes transiently expressed by sensitive cells in response to a single X-ray dose. The repeated treatments received during fractionated irradiation may promote the change from a transient to a constitutive pattern of gene expression.

Taxane‐Platinum Combinations in Advanced Non‐Small Cell Lung Cancer: A Review

Platinum-based chemotherapy is the treatment of choice for patients with non-small cell lung cancer (NSCLC). As a result of their single-agent activities and synergistic effects, taxane-platinum combinations are often used as first-line therapy for this disease. Four large, multicenter, randomized phase III clinical trials (the TAX 326 trial, the Southwest Oncology Group 9509 trial, the Italian Lung Cancer Project, and the Eastern Cooperative Oncology Group 1594 trial) have compared taxane-platinum combinations (docetaxel and paclitaxel) with other platinum combinations (vinorelbine and gemcitabine) in chemotherapy-naïve patients with good performance status scores and advanced disease. The end points for these large randomized clinical trials were survival, response rate, adverse events, and quality of life (QOL). Of the taxane-platinum combinations tested, docetaxel-cisplatin was the only platinum combination to yield survival and response rates superior to another platinum combination. In adverse event terms, the taxane-platinum combination of paclitaxel-carboplatin demonstrated less grade 3 or 4 neutropenia and lower rates of febrile neutropenia than other taxane-platinum combinations but higher rates of irreversible grade 3 or 4 peripheral neuropathy than any of the other taxane-platinum combinations. Additional differences emerged when QOL data were evaluated. The docetaxel-platinum combination demonstrated broad QOL benefits for patients receiving this combination, and this benefit was not observed with the other platinum or taxane-platinum combinations. As our use of these taxane-platinum combinations expands, these differences in survival, response rate, adverse events, and QOL will permit us to better balance our treatment goals for all patients with all stages of NSCLC.