Phase I studies of imatinib mesylate combined with cisplatin and irinotecan in patients with small cell lung carcinoma

A novel NCI-H69V small cell lung cancer functional mini-tumor model for future treatment screening applications

Small cell lung cancer (SCLC) is aggressive and despite multiple clinical trials, its standard of care is unchanged for the past three decades. In vitro cancer models are crucial in chemotherapy development, and three-dimensional (3D) models aim to bridge the gap between two-dimensional (2D) flat cultures and in vivo testing. Functional 3D spheroids can better represent the in vivo situation and tumor characteristics than 2D models. An NCI-H69V SCLC mini-tumor model was developed in a clinostat-based rotating bioreactor system. Spheroid growth and viability were characterized for 30 days, and the ideal experimental window with mature and metabolically stable spheroids was determined. Application of the model for anticancer treatment screening was validated with the standard chemotherapeutic drug irinotecan, for an exposure period of 72 h. The following parameters were measured: soluble protein content, planar surface area measurements, intracellular adenosine triphosphate and extracellular adenylate kinase levels, and glucose consumption. Histological morphology of the spheroids was observed. The established model proved viable and stable, while treatment with irinotecan caused a decrease in cell growth, viability, and glucose consumption demonstrating reactivity of the model to chemotherapy. Therefore, this NCI-H69V SCLC functional spheroid model could be used for future anticancer compound screening.

Individualization of Irinotecan Treatment: A Review of Pharmacokinetics, Pharmacodynamics, and Pharmacogenetics

Since its clinical introduction in 1998, the topoisomerase I inhibitor irinotecan has been widely used in the treatment of solid tumors, including colorectal, pancreatic, and lung cancer. Irinotecan therapy is characterized by several dose-limiting toxicities and large interindividual pharmacokinetic variability. Irinotecan has a highly complex metabolism, including hydrolyzation by carboxylesterases to its active metabolite SN-38, which is 100- to 1000-fold more active compared with irinotecan itself. Several phase I and II enzymes, including cytochrome P450 (CYP) 3A4 and uridine diphosphate glucuronosyltransferase (UGT) 1A, are involved in the formation of inactive metabolites, making its metabolism prone to environmental and genetic influences. Genetic variants in the DNA of these enzymes and transporters could predict a part of the drug-related toxicity and efficacy of treatment, which has been shown in retrospective and prospective trials and meta-analyses. Patient characteristics, lifestyle and comedication also influence irinotecan pharmacokinetics. Other factors, including dietary restriction, are currently being studied. Meanwhile, a more tailored approach to prevent excessive toxicity and optimize efficacy is warranted. This review provides an updated overview on today’s literature on irinotecan pharmacokinetics, pharmacodynamics, and pharmacogenetics.

The transcriptional regulator FUBP1 influences disease outcome in murine and human myeloid leukemia

The transcriptional regulator far upstream element binding protein 1 (FUBP1) acts as an oncoprotein in solid tumor entities and plays a role in the maintenance of hematopoietic stem cells. However, its potential function in leukemia is unknown. In murine models of chronic (CML) and acute myeloid leukemia (AML) induced by BCR-ABL1 and MLL-AF9, respectively, knockdown of Fubp1 resulted in prolonged survival, decreased numbers of CML progenitor cells, decreased cell cycle activity and increased apoptosis. Knockdown of FUBP1 in CML and AML cell lines recapitulated these findings and revealed enhanced DNA damage compared to leukemia cells expressing wild type FUBP1 levels. FUBP1 was more highly expressed in human CML compared to normal bone marrow cells and its expression correlated with disease progression. In AML, higher FUBP1 expression in patient leukemia cells was observed with a trend toward correlation with shorter overall survival. Treatment of mice with AML with irinotecan, known to inhibit topoisomerase I and FUBP1, significantly prolonged survival alone or in combination with cytarabine. In summary, our data suggest that FUBP1 acts as cell cycle regulator and apoptosis inhibitor in leukemia. We demonstrated that FUBP1 might play a role in DNA repair, and its inhibition may improve outcome in leukemia patients.

Anti-angiogenesis in Personalized Therapy of Lung Cancer

Upregulation of angiogenesis is a frequent occurrence in lung cancer and is reported to represent a negative prognostic factor. This provides a rationale for the development and evaluation of anti-angiogenic agents. To date bevacizumab, a monoclonal antibody directed against serum VEGF, is the only anti-angiogenic agent that has demonstrated improved overall survival for patients with lung cancer. Meta-analysis of trials of bevacizumab in combination with platinum-based chemotherapy for NSCLC, show a 10% reduction in the risk of death (HR 0.90, 95% CI 0.81-0.99). However, therapy with bevacizumab is limited to NSCLC patients with non-squamous histology, good performance status, no brain metastases and the absence of bleeding or thrombotic disorders. More recently, similar survival was observed in a non bevacizumab containing regimen of carboplatin, pemetrexed and maintenance pemetrexed. Multiple oral anti-angiogenic compounds have been evaluated in NSCLC, both in first-line therapy, or upon disease progression. The majority of agents have shown some evidence of activity, but none have clearly demonstrated improvements in overall survival. Increased toxicities have been observed, including an increased risk of death for some agents, limiting their development. Promising data exist for sunitinib in patients with heavily pre-treated NSCLC, and nintedanib in combination with docetaxel, as second-line therapy for NSCLC. However, these findings require validation. Currently, there is no established role for anti-angiogenic therapy in SCLC, although there is some promise for sunitinib as maintenance therapy following platinum and etoposide chemotherapy. The challenge for anti-angiogenic therapy is to understand whether treatment effects in a subpopulation, are lost among a larger unselected population of patients. There is a need for additional translational research to identify predictive biomarkers for anti-angiogenic therapy.

Detection of c-kit mutational status in small-cell lung cancer in a Chinese cohort

BACKGROUND

Overexpression of KIT (CD117), a tyrosine kinase receptor, and its natural ligand, stem cell factor, are found in small-cell lung cancer (SCLC). Somatic mutations of the proto-oncogene c-kit constitutively activate KIT expression in a ligand-independent way. To explore the clinical value of the c-kit mutation as a potential target for therapy with tyrosine kinase inhibitors, the c-kit mutational status and KIT expression in tumors from Chinese patients with SCLC were analyzed.

METHODS

Using 107 paraffin-embedded SCLC tumor specimens, c-kit exons 9, 11, 13, and 17 were analyzed for mutations by polymerase chain reaction and direct sequencing.

RESULTS

There were no activating mutations in exons 9, 11, 13, or 17. However, a point mutation in intron 16 (81240 G>A) was found in 11 out of the 107 samples (10.3%), of which the majority were limited-stage SCLC (10/11, 90.9%). Immunohistochemical staining of tumors harboring the c-kit point mutation using the anti-CD117 antibody showed that the mutation status was not associated with the expression of KIT.

CONCLUSION

These findings indicate that the incidence and the types of c-kit mutations in SCLC tumors found in Chinese are different from those of the Caucasian population. Nevertheless, c-kit mutations are similarly rare in both groups, implying that they may not be suitable targets for c-kit-based tyrosine kinase inhibitors.

The development of targeted therapy in small cell lung cancer

Small cell lung cancer (SCLC) is a highly aggressive cancer usually with distal metastasis and very poor prognosis. Chemotherapy is the treatment of choice for SCLC in all stages and an initial good response, but there is a high chance of disease relapse with an overall poor median survival for both stages. With increasing translational research and a better understanding of the molecular basis of cancer, a number of molecular targets have been identified in various preclinical studies. Targeted drugs have less toxicity than chemotherapy drugs, but no targeted agents have been approved for use in the treatment of SCLC patients to date. This review focuses on targeted therapies in SCLC.

A Phase I clinical trial of the combination of imatinib and paclitaxel in patients with advanced or metastatic solid tumors refractory to standard therapy

PURPOSE

Pre-clinical data suggest that combining imatinib with traditional cytotoxic chemotherapy may improve imatinib efficacy. We conducted a Phase I study of imatinib in combination with paclitaxel in patients with advanced or metastatic solid tumors.

METHODS

Patients were accrued to the study in a standard 3 + 3 design. Patients were restaged every two cycles, and those with stable disease (SD), or better, continued study treatment without interruption. Maximally tolerated doses (MTDs) and pharmacokinetic profiles of combination imatinib and paclitaxel were assessed.

RESULTS

Fifty-eight patients were enrolled, including 40 in the Phase I dose escalation portion. Alternating dose escalation of imatinib and paclitaxel on a 28-day cycle resulted in MTDs of 800 mg imatinib daily, on days 1-4, 8-11, 15-18, and 22-25, and 100 mg/m(2) paclitaxel weekly, on days 3, 10, and 17. Two expansion cohorts, comprising 10 breast cancer patients and 8 patients with soft-tissue sarcomas, were enrolled at the MTDs. The most common adverse events were flu-like symptoms (64 %) and nausea/vomiting (71 %). The most common Grade 3/4 toxicities were neutropenia (26 %), flu-like symptoms (12 %), and pain (12 %). There were no relevant differences in the pharmacokinetic profiles of either drug when given in combination compared with alone. Thirty-eight subjects were evaluable for response, 18 (47.4 %) of whom experienced clinical benefit. Five patients (13.2 %) had a partial response (PR) and 13 patients (34.2 %) had SD; the average time to progression in those with clinical benefit was 17 weeks (range: 7-28 weeks).

CONCLUSIONS

This combination of imatinib and paclitaxel was reasonably safe and tolerable, and demonstrated evidence of anti-tumor activity. Further exploration in disease-specific Phase II trials is warranted.

Management of small cell lung cancer: recent developments for optimal care

Small cell lung cancer (SCLC) represents approximately 13% of all lung cancer diagnoses and the incidence has reduced over the last 20 years. Treatment of SCLC remains challenging because of its rapid growth, early dissemination and development of drug resistance during the course of the disease. Chemotherapy remains the cornerstone of treatment for limited (LD) and extensive disease (ED), with concurrent chemotherapy and radical thoracic radiotherapy representing the best treatment option for fit patients with LD. Platinum-based chemotherapy is the treatment of choice in fit patients with good organ function, and the radiosensitizing effect of cisplatin is critically important for concurrent chemoradiotherapy in LD. Anthracycline-containing regimens represent a viable alternative for patients where platinum-based chemotherapy is contraindicated. Patients who relapse or progress after first-line chemotherapy have a very poor prognosis. Second-line therapy may produce a modest clinical benefit. Maintenance chemotherapy has not been shown to convincingly improve outcomes for SCLC. A number of targeted agents have been investigated in LD and ED, mostly in unselected populations, with disappointing results. Prophylactic cranial irradiation has been shown to reduce the incidence of brain metastases and prolong survival for both LD and ED without negative impact on quality of life (QOL) and cognitive function. Ongoing trials will shed some light on the impact of thoracic radiotherapy on QOL, symptom control and survival in ED SCLC patients who benefitted from first-line chemotherapy.

Molecular biology of lung cancer: clinical implications

Lung cancer is a heterogeneous disease clinically, biologically, histologically, and molecularly. Understanding the molecular causes of this heterogeneity, which might reflect changes occurring in different classes of epithelial cells or different molecular changes occurring in the same target lung epithelial cells, is the focus of current research. Identifying the genes and pathways involved, determining how they relate to the biological behavior of lung cancer, and their utility as diagnostic and therapeutic targets are important basic and translational research issues. This article reviews current information on the key molecular steps in lung cancer pathogenesis, their timing, and clinical implications.

Update on new drugs in small cell lung cancer

INTRODUCTION

Small cell lung cancer (SCLC) will account for 25,000 to 32,000 new lung cancer cases in the USA in 2010. Current treatmenta pproaches include platinum-based chemotherapy and etoposide with or without radiation therapy depending on stage and performance status. Five-year survival is approximately 25% for patients with limited stage disease and 1 -- 2% for patients with extensive stage disease and has noti mproved in almost two decades.

AREAS COVERED

This article reviews the results of recent clinical trials that have evaluated targeted agents and novel cytotoxic agents alone or in combination with standard chemotherapy in the treatment of patients with SCLC.

EXPERT OPINION

The lack of a targeted approach to the treatment of patients with SCLC has led investigators to evaluate a multitude of agents with overwhelmingly negative results. A more systematic approach to clinical trials in patients is needed to improve outcomes for patients with this disease.

Sorafenib in platinum-treated patients with extensive stage small cell lung cancer: a Southwest Oncology Group (SWOG 0435) phase II trial

INTRODUCTION

Sorafenib is a multikinase inhibitor affecting pathways involved in tumor progression and angiogenesis. We conducted a phase II trial of sorafenib in platinum-treated patients with extensive stage small cell lung cancer to determine the tumor response rate, toxicity, and overall survival.

METHODS

Patients with histologically confirmed, measurable disease, Zubrod performance status 0 to 1, and no more than 1 prior platinum-based treatment were eligible. Patients were stratified by platinum-sensitivity status: sensitive (progression >90 days after platinum) or refractory (progression during or ≤90 days after platinum). Patients were treated with sorafenib 400 mg orally twice a day continuously on a 28-day cycle.

RESULTS

Of 89 patients registered, 82 were evaluable for toxicity assessment, and 83 were evaluable for response. There were four partial responses seen among the 38 patients in the platinum-sensitive stratum, for an estimated response rate of 11% (95% confidence interval: 3-25%), and one partial response among the 45 patients in the platinum-refractory stratum, for an estimated response rate of 2% (95% confidence interval: 0-12%). The median overall survival estimates were 6.7 months (95% confidence interval: 6.1-9.1 months) for the platinum-sensitive stratum and 5.3 months (95% confidence interval: 3.3-7.5 months) in the platinum-refractory stratum. Nineteen patients discontinued treatment because of adverse events or side effects from therapy.

CONCLUSIONS

Based on the lack of disease control seen in our trial, further investigation of single-agent sorafenib in the small cell lung cancer population is not recommended. Combination trials of sorafenib and chemotherapy are ongoing.

Multicenter phase II trial assessing effectiveness of imatinib mesylate on relapsed or refractory KIT-positive or PDGFR-positive sarcoma

BACKGROUND

Imatinib myselate is a molecularly targeted drug that inhibits Abl tyrosine kinase, as well as type III tyrosine kinase receptors such as platelet-derived growth factor receptor (PDGFR), KIT, colony-stimulating factor 1 receptor (CSF-1R), and discoidin domain receptor (DDR). Ph1 chromosome-positive chronic myeloid leukemias (CMLs), KIT-positive gastrointestinal stromal tumors (GISTs), and PDGFR-positive dermatofibrosarcoma protuberans (DFSP) have been reported to be responsive to imatinib treatment. We conducted a multicenter Phase II trial of imatinib in patients with relapsed or refractory KIT-positive (excluding GISTs) or PDGFR-positive sarcomas.

METHODS

Patient ages ranged from 12 and 75 years. Eligibility criteria included (1) metastatic sarcomas with a definitive diagnosis based on histopathology or that were completely unresectable and locally advanced; (2) relapsed or refractory cases that had completed standard treatment; and (3) a tumor confirmed by immunohistochemical staining to be KIT- or PDGFR-positive. A 600-mg dose of imatinib was administered to patients once a day, with each patient receiving six courses of the drug and each course lasting 4 weeks. In cases categorized as stable or progressive, the imatinib dose was increased to 800 mg/day administered twice daily.

RESULTS

A total of 25 patients who met the eligibility criteria were enrolled in the trial; 22 were evaluated for response. The response rate with a 600 mg/day dose of imatinib was 4.5% (0 complete response, 1 partial response). There were no other objective responses after increasing imatinib to 800 mg/day (0/10). We estimated 50% progression-free survival to be 61.0 days for an imatinib dose of 600 mg/day based on the Kaplan-Meier method. Side effects of imatinib were generally similar to those observed in previous clinical trials.

CONCLUSIONS

Our results did not indicate effectiveness of imatinib monotherapy at a dose of 600 or 800 mg/day in patients with relapsed or refractory KIT-positive (excluding GISTs) or PDGFR-positive sarcomas. Our findings suggest the need to evaluate the synergistic effect of combination therapy with other anticancer drugs.

[Molecular targeted therapies in small-cell lung cancer]

Small-cell lung cancers (SCLC) are aggressive malignancies, however, characterized by high primary chemosensitivity. Unfortunately, for the vast majority of patients, relapse is the rule with emergence of secondary resistance mechanisms. In the era of molecular targeted therapies, characterization of a number of molecular abnormalities has encouraged implementation of several clinical trials. This literature review summarizes the various pharmacological approaches used in SCLC to improve survival in localized and extensive forms of the disease. Initial trials with molecular targeted therapies have not been able to improve clinical outcome compared to the standard etoposide-cisplatin chemotherapy regimen in extensive forms. However, new targets continue to be identified and many treatments are currently being assessed, including blockade of angiogenesis, signal transduction, cell cycle or induction of apoptosis.

Targeted therapies in small cell lung cancer: a review

Small cell lung cancer (SCLC) is an aggressive form of lung cancer that is characterized by a rapid doubling time, early onset of dissemination and high sensitivity to chemotherapy. Despite the potential for cure in patients with limited disease with concurrent chemoradiation and an initial good response to chemotherapy in extensive disease, there is a high chance of disease relapse with an overall poor median survival for both stages. With increasing translational research and a better understanding of the molecular basis of cancer, a number of molecular targets have been identified in various preclinical studies. This review summarizes potentially viable targets and new agents that have been developed and employed in recent, ongoing and future clinical trials to attempt to improve clinical outcomes in this disease.

Combination of KIT gene silencing and tocopherol succinate may offer improved therapeutic approaches for human mastocytosis

Gain-of-function mutations of kit tyrosine kinase receptor are associated with mastocytosis. Two subclones of the HMC1 mast leukaemia cell line were used; both express an identical KIT allele-specific regulatory type mutation (V560G), but differ in that one also expresses an enzymatic site type mutation (D816V) that confers on them resistance to imatinib mesylate tyrosine kinase inhibitor. In both cell lines, proliferation was suppressed and apoptosis induced by the combination of KIT gene silencing and alpha-tocopherol succinate (alpha-TOS), a derivate of alpha-tocopherol, also known as vitamin E. Furthermore, HMC1 cells with decreased kit levels by KIT silencing, failed to form tumours when xenotransplanted into immunocompromised mice and the animals were treated systemically with alpha-TOS. Targeting kit in the presence of alpha-TOS represents a new approach against proliferation of human mast leukaemia cell lines.

Paracrine signaling by platelet-derived growth factor-CC promotes tumor growth by recruitment of cancer-associated fibroblasts

Cancer results from the concerted performance of malignant cells and stromal cells. Cell types populating the microenvironment are enlisted by the tumor to secrete a host of growth-promoting cues, thus upholding tumor initiation and progression. Platelet-derived growth factors (PDGF) support the formation of a prominent tumor stromal compartment by as of yet unidentified molecular effectors. Whereas PDGF-CC induces fibroblast reactivity and fibrosis in a range of tissues, little is known about the function of PDGF-CC in shaping the tumor-stroma interplay. Herein, we present evidence for a paracrine signaling network involving PDGF-CC and PDGF receptor-alpha in malignant melanoma. Expression of PDGFC in a mouse model accelerated tumor growth through recruitment and activation of different subsets of cancer-associated fibroblasts. In seeking the molecular identity of the supporting factors provided by cancer-associated fibroblasts, we made use of antibody arrays and an in vivo coinjection model to identify osteopontin as the effector of the augmented tumor growth induced by PDGF-CC. In conclusion, we establish paracrine signaling by PDGF-CC as a potential drug target to reduce stromal support in malignant melanoma.

c-Abl activates p38 MAPK independently of its tyrosine kinase activity: Implications in cisplatin-based therapy

Activation of p38 MAPK is a critical requisite for the therapeutics activity of the antitumor agent cisplatin. In this sense, a growing body of evidences supports the role of c-Abl as a major determinant of p38 MAPK activation, especially in response to genotoxic stress when triggered by cisplatin. Here, we demonstrate that p38 MAPK activation in response to cisplatin does not require the tyrosine kinase activity of c-Abl. Indeed, c-Abl can activate the p38 MAPK signaling pathway by a mechanism that is independent of its tyrosine kinase activity, but that instead involves the ability of c-Abl to increase the stability of MKK6. Similar results were obtained in chronic myeloid leukemia-derived cell lines, in which a chimeric Bcr/Abl protein mimics the effects of c-Abl overexpression on p38 MAPK activation. These findings may explain why a clinically used c-Abl inhibitor, imatinib mesylate, fails to inhibit the p38 MAPK pathway alone or in combination with cisplatin, and provide evidence of a novel signaling mechanism in which these antitumor agents act.

Impact of imatinib on the pharmacokinetics and in vivo efficacy of etoposide and/or ifosfamide

Background

Using a human small cell lung cancer (SCLC) xenografted in nude mice, we have previously reported enhanced tumor growth inhibition following chemotherapy in combination with imatinib (STI571). We therefore investigated the in vivo impact of imatinib on the pharmacokinetics and efficacy of chemotherapy.

Methods

Two different human tumors were used: SCLC6 small cell lung cancer xenografted in nude mice, and LY-3 EBV-associated human B-cell lymphoma xenografted in SCID mice. Plasma, urine, and fecal concentrations of etoposide (VP16) were determined by a validated high performance liquid chromatography method. Plasma concentrations of ifosfamidewere determined by a validated gas chromatography assay with nitrogen-phosphorus detection.

Results

Slight tumor growth inhibition was induced by imatinib administered alone in one in vivo EBV-associated B-cell lymphomatous xenograft. In contrast, an increase of the chemotherapy-induced antitumor effect was observed in the lymphoma model but not in a small cell lung cancer model when mice bearing human xenografted tumors were treated concomitantly by imatinib and chemotherapy. This antitumor effect was not influenced by concomitant administration of fluconazole. The AUC0-3 h (Area Under the concentration-time Curve) of etoposide was increased when mice were treated with etoposide + imatinib due to decreased fecal excretion. In contrast, imatinib did not appear to influence the urinary excretion of etoposide, and concomitant administration of the CYP3A4 inhibitor, fluconazole, with imatinib did not modify the pharmacokinetics of etoposide plus imatinib alone.

Conclusion

Altogether, these results therefore justify further prospective phase I and II clinical trials with combinations of etoposide-based chemotherapy and imatinib in patients with certain cancers, such as malignant lymphoma, with careful toxicologic monitoring.

Targeted therapies in small-cell lung cancer

Small-cell lung cancer is an aggressive form of lung cancer that, overall, remains the most common cause of cancer death in the US. Some advances have been made in the treatment of small-cell lung cancer using cytotoxic chemotherapeutic agents but no truly targeted therapies are available as of yet. At present, research is focused on finding therapies that can target the specific molecular mechanisms responsible for the survival, growth and metastasis of the tumor thereby improving responses to chemotherapy and minimizing toxicity. Several new agents, such as angiogenesis inhibitors and regulators of apoptosis, have reached clinical testing and multiple others are in preclinical trials. Some of these will be discussed in this review.

Irinotecan, Carboplatin, and Imatinib in Untreated Extensive-Stage Small-Cell Lung Cancer: A Phase II Trial of the Minnie Pearl Cancer Research Network

INTRODUCTION

The tyrosine kinase KIT has variable expression in small-cell lung cancer (SCLC) and may be a prognostic factor. Imatinib targets KIT expression, providing rationale for studying its role in combination with chemotherapy in SCLC in a multicenter phase II trial.

METHODS

Patients with untreated extensive-stage SCLC received carboplatin area under the concentration-time curve of 4 on day 1; irinotecan 60 mg/m2 on days 1, 8, and 15; and imatinib 600 mg/day. Treatment cycles were 28 days. Patients remained on imatinib until progressive disease or significant toxicity.

RESULTS

Between September 2002 and May 2004, 68 patients were enrolled in this multicenter trial. Median age was 60 years (range, 37-81). The objective response rate was 66% (95% confidence interval: 54%-76%). Median progression-free survival was 5.4 months (95% CI: 4.3-6.0 months). Median overall survival was 8.4 months (95% CI: 6.3-10.5 months). Thirty-five percent of patients were alive at 1 year. Grade 3/4 hematologic toxicity included neutropenia (43%), anemia (16%), and thrombocytopenia (9%). Grade 3 nonhematologic toxicity included diarrhea (19%), fatigue (24%), and nausea (26%). Forty-eight of 56 patients (86%) with available tumor specimens had KIT expression detected. KIT expression did not appear to correlate with progression-free survival or overall survival in a retrospective analysis.

CONCLUSIONS

Irinotecan, carboplatin, and imatinib is a safe and generally well-tolerated regimen in patients with SCLC. However, the addition of imatinib did not improve results from those expected with chemotherapy alone.

Bleomycin, etoposide and cisplatin (BEP) combination with concurrent imatinib mesylate (GLEEVEC) in chronic myeloid leukemia (CML) patient with mesenchymal tumor

Imatinib is now indicated as the first line therapy for chronic myeloid leukemia (CML). Treatment of CML with imatinib is generally well tolerated and the risk of severe adverse affects is low. Many new drugs including targeted therapy are combined with antineoplastic agents safely. We here report a patient with CML who developed concurrent mesenchymal tumor while undergoing therapy with imatinib and treated with combination chemotherapy including bleomycin, etoposide, and cisplatin, as well as imatinib without severe toxicity.

Induction of urokinase-type plasminogen activator, interleukin-8 and early growth response-1 by STI571 through activating mitogen activated protein kinase in human small cell lung cancer cells

We previously demonstrated the simultaneous induction of urokinase-type plasminogen activator and interleukin-8, a CXC chemokine, in doxorubicin-treated human NCI-H69 small cell lung cancer cells in which extracellular signal-regulated kinase 1/2 and p38 mitogen-activated protein kinase might be involved. NCI-H69 cells expressed one of the receptor tyrosine kinases, c-Kit, and STI571 inhibited the cell growth and stem cell factor-induced phosphorylation of c-Kit. We therefore investigated the effects of STI571 on the expression of urokinase-type plasminogen activator and interleukin-8 in NCI-H69 cells. Microarray analysis revealed the gene induction of not only urokinase-type plasminogen activator and interleukin-8, but also early growth response-1 in STI571-treated cells. Treatment with STI571 resulted in the induction of phosphorylation of all three mitogen-activated protein kinases, such as extracellular signal-regulated kinase 1/2, p38 mitogen-activated protein kinase and stress-activated protein kinase/c-jun N-terminal protein kinase. U0126, an inhibitor against extracellular signal-regulated kinase 1/2, however, only inhibited the STI571-induced interleukin-8 accumulation. Urokinase-type plasminogen activator and interleukin-8 are important biological factors in tumor cell regulation; STI571 may therefore influence many aspects of tumor cell biology through inducing urokinase-type plasminogen activator and interleukin-8, in which the induction of early growth response-1 expression and extracellular signal-regulated kinase 1/2 phosphorylation might be involved.

Small cell lung cancer and targeted therapies

PURPOSE OF REVIEW

Small cell lung cancer is a chemosensitive malignancy, yet long-term survival remains elusive for the majority of patients. Here, we report on progress in evaluating novel targeted therapies for the treatment of this disease.

RECENT FINDINGS

Interferons, matrix metalloproteinase inhibitors, thalidomide, bevacizumab, ZD6474, imatinib, gefitinib, oblimersen and aplidine have all entered clinical trial in patients with small cell lung cancer. Immunotherapy approaches targeting cell surface antigens such as CD-56 (BB10901) and GD3 ganglioside are also being evaluated. Interferons, matrix metalloproteinase inhibitors, imatinib and gefitinib have failed to demonstrate efficacy for this disease. Preliminary data for thalidomide are promising and so results from trials of other antiangiogenics such as bevacizumab and ZD6474 are awaited with interest.

SUMMARY

Although the promise of targeted therapy has yet to be realized in patients with small cell lung cancer, the number of agents available for evaluation provides new optimism that progress will be made over the next decades.

Camptothecin acts synergistically with imatinib and overcomes imatinib resistance through Bcr-Abl independence in human K562 cells

In this study, we have tried to find new targets and effective drugs for imatinib-resistant chronic myelogenous leukemia (CML) cells displaying loss of Bcr-Abl kinase target dependence. The imatinib-resistant K562/R1, -R2 and -R3 cells showed profound declines of Bcr-Abl level and concurrently exhibited up-regulation of Bcl-2 and Ku70/80, and down-regulation of Bax, DNA-PKcs and BRCA1, suggesting that loss of Bcr-Abl after exposure to imatinib might be accompanied by other cell survival mechanism. K562/R3 cells were more sensitive to camptothecin (CPT)- and radiation-induced apoptosis than K562 cells, indicating hypersensitivity of imatinib-resistant cells to DNA damaging agents. Moreover, when K562 cells were treated with the combination of imatinib with CPT, the level of Bax and the cleavage of PARP-1 and DNA-PK were significantly increased in comparison with the effects of each drug. Therefore, our study suggests that CPT can be used to treat CML with loss of Bcr-Abl expression.

The role of STATs in lung carcinogenesis: an emerging target for novel therapeutics

The signal transducer and activator of transcription (STAT) proteins are a family of latent cytoplasmic transcription factors, which form dimers when activated by cytokine receptors, tyrosine kinase growth factor receptors as well as non-receptor tyrosine kinases. Dimeric STATs translocate to the nucleus, where they bind to specific DNA-response elements in the promoters of target genes, thereby inducing unique gene expression programs often in association with other transcription regulatory proteins. The functional consequence of different STAT proteins activation varies, as their target genes play diverse roles in normal cellular/tissue functions, including growth, apoptosis, differentiation and angiogenesis. Certain activated STATs have been implicated in human carcinogenesis, albeit only few studies have focused into their role in lung tumours. Converging evidence unravels their molecular interplays and complex multipartite regulation, rendering some of them appealing targets for lung cancer treatment with new developing strategies.

The broken genome: genetic and pharmacologic approaches to breaking DNA

The RecQ family of DNA helicases consists of specialized DNA unwinding enzymes that promote genomic stability through their participation in a number of cellular processes, including DNA replication, recombination, DNA damage signaling, and DNA repair pathways. Mutations resulting in the inactivation of some but not all members of the RecQ helicase family can lead to human syndromes which are characterized by marked chromosomal instability and an increased predisposition to cancer. An evolutionarily conserved interaction between RecQ helicases and topoisomerase 3s has been established, and this interaction is important in the regulation of recombination and genomic stability. Topoisomerases are critical in the cell because they relieve helical stress that arises when DNA is unwound. Topoisomerases function by breaking and rejoining DNA. By inhibition of the rejoining function, topoisomerase inhibitors are potent chemotherapeutic agents that have been used successfully in the treatment of hematologic malignancies and other cancers. This review discusses the roles of RecQ helicases in genomic stability, the interplay between RecQ helicases and topoisomerase 3s, and current and future prospects for targeting these interactions to develop novel anticancer therapies.

Topoisomerase I inhibitors: camptothecins and beyond

Nuclear DNA topoisomerase I (TOP1) is an essential human enzyme. It is the only known target of the alkaloid camptothecin, from which the potent anticancer agents irinotecan and topotecan are derived. As camptothecins bind at the interface of the TOP1-DNA complex, they represent a paradigm for interfacial inhibitors that reversibly trap macromolecular complexes. Several camptothecin and non-camptothecin derivatives are being developed to further increase anti-tumour activity and reduce side effects. The mechanisms and molecular determinants of tumour response to TOP1 inhibitors are reviewed, and rational combinations of TOP1 inhibitors with other drugs are considered based on current knowledge of repair and checkpoint pathways that are associated with TOP1-mediated DNA damage.