Kenji Tamura

Small interfering RNA targeting survivin sensitizes lung cancer cell with mutant p53 to adriamycin

Survivin is a member of the inhibitor of apoptosis protein (IAP) family that is specifically overexpressed in cancer tissues. p53 is one of the tumor suppressor genes; its induction in response to DNA damage causes apoptosis and correlates with drug sensitivity. To investigate the possible regulation of survivin by p53, we examined the level of survivin expression in lung cancer cell lines in response to adriamycin. Levels of survivin mRNA and protein in cell lines with wild‐type p53 decreased dramatically after p53 induction, but no such reduction of survivin was observed in cell lines with mutated or null p53. Inhibition of wild‐type p53 in A549 cells by small interfering (si) RNA significantly upregulated the expression of survivin. Survivin inhibition by siRNA in PC9 cells with mutated p53 significantly depressed cell proliferation. To investigate the sensitivity of cancer cells to adriamycin after inhibition of survivin, we depressed survivin expression using siRNA, and then added adriamycin at an IC50 dose. After a further 48 hr incubation with adriamycin, proliferation was significantly depressed in the cells treated with siRNA targeting survivin, in comparison with siRNA targeting scramble. Furthermore, both TUNEL and pro‐caspase3 expression assay showed a significant increase in apoptosis after combined treatment with adriamycin and siRNA targeting survivin. Our results demonstrate that survivin is downregulated by p53, and that siRNA targeting of survivin increases cell sensitivity to adriamycin and promotes apoptosis. siRNA targeting of survivin could be potentially useful for increasing sensitivity to anticancer drugs, especially in drug‐resistant cells with mutated p53.

Gefitinib in non-small cell lung cancer

Gefitinib (IressaTM), an orally-active tyrosine kinase inhibitor of the epidermal growth factor receptor (EGFR), is the first approved molecular-targeted drug for the management of patients with advanced non-small cell lung cancer (NSCLC). Two Phase II trials (IDEAL [Iressa Dose Evaluation in Advanced Lung Cancer]-1 and -2), evaluated the efficacy of gefitinib in advanced NSCLC patients who received ≤ 2 (IDEAL1) or ≥ 2 (IDEAL2) previous chemotherapy regimens. The response rate and disease control rate in IDEAL1 and -2 was 18/12% and 54/42%, respectively. The median survival time and one-year survival rate in both studies were ~ 7 months and 30%, respectively. As gefitinib has demonstrated antitumour activity and an acceptable tolerability profile not typically associated with cytotoxic adverse events, such as hematological toxicities, combinations with cytotoxic drugs have been evaluated. Disappointingly, in chemotherapy-naive patients with advanced NSCLC, gefitinib 250 and 500 mg/day combined with platinum-based chemotherapy (gemcitabine/cisplatin or paclitaxel/carboplatin) did not produce prolonged survival, compared with chemotherapy alone in two large, randomised, placebo-controlled, multi-centre Phase III trials (INTACT [Iressa NSCLC Trial Assessing Combination Treatment]-1 and -2). Furthermore, in a recent randomised, placebo-controlled, Phase III trial (ISEL: IRESSA Survival Evaluation in Lung cancer), gefitinib failed to prolong survival compared with placebo in patients with advanced NSCLC who had failed one or more lines of chemotherapy. Subgroup analysis of ISEL suggested improved survival in patients of Asian origin and non-smokers. In addition, subset analyses of IDEAL and several retrospective studies have indicated that female gender, adenocarcinoma histology (especially bronchial alveolar carcinoma), non-smoker status and Asian ethnicity are factors which predict to response to gefitinib. Two types of somatic mutation clustered around the ATP binding pocket in the tyrosine kinase domain of the EGFR gene have been reported as possible surrogate biological markers for predicting response to gefitinib. Appropriate patient selection by clinical characteristics or genetical information is needed, both for future clinical trials of gefitinib and its routine use in the clinic among patients with advanced NSCLC.

Deletion of three distinct regions on chromosome 13q in human non-small-cell lung cancer.

We examined loss of heterozygosity (LOH) at the retinoblastoma susceptibility gene (RBI) locus on chromosome 13q14 in 20 non‐small‐cell lung cancers (NSCLCs) using polymorphic markers. The expression of RB protein was examined by immunohistochemical analysis of paraffin‐embedded specimens of the same tumors. The results revealed that 10 of 16 informative cases showed an LOH at the RBI locus, whereas only 2 of the 10 tumors lost expression of the RB protein. These 2 tumors had mutations in the remaining RBI allele. Thus, inactivation of the RBI gene appears to be involved in a small subset of NSCLCs only. To elucidate the presence of tumor‐suppressor genes other than RBI on 13q, heterozygosity at 15 different loci was investigated. Of 20 tumors analyzed, 15 showed an LOH at least at one locus, and the regions 13q12.1‐qter, 13q12.2–14.2 and 13q14.1–q14.3, including the RBI locus, were deleted in significant numbers of the tumors. Our results suggest that, in addition to the RBI gene, abnormalities of other tumor‐suppressor genes on chromosome 13q are involved in the development of human NSCLCs. Int. J. Cancer 74:45–49.

Phase I study of TZT-1027, a novel synthetic dolastatin 10 derivative and inhibitor of tubulin polymerization, which was administered to patients with advanced solid tumors on days 1 and 8 in 3-week courses

PurposeTo determine the maximum tolerated dose (MTD), dose-limiting toxicity (DLT), and pharmacokinetics of TZT-1027 (soblidotin), a dolastatin 10 analogue, in Japanese patients with advanced solid tumors when administered on days 1 and 8 in 3-week courses.MethodsEligible patients had advanced solid tumors that failed to respond to standard therapy or for which no standard therapy was available, and also met the following criteria: prior chemotherapy ≤2 regimens, Eastern Cooperative Oncology Group (ECOG) performance status ≤1, and acceptable organ function. The MTD was defined as the highest dose at which no more than one of six patients experienced a DLT during course 1. Pharmacokinetic samples were collected in courses 1 and 2.ResultsEighteen patients were enrolled in the present study. Three doses (1.5, 1.65, and 1.8xa0mg/m2) were evaluated. Neutropenia was the principal DLT at doses of 1.65 and 1.8xa0mg/m2. In addition, one patient also experienced grade 3 pneumonia with neutropenia, and another patient experienced grade 3 constipation, neuropathy, grade 4 neutropenia, and hyponatremia as DLTs at 1.65xa0mg/m2. Phlebitis, the most frequent nonhematological toxicity, was improved by administration of additional saline after TZT-1027 administration. The MTD was 1.5xa0mg/m2, at which DLT was not observed in a total of nine patients. The pharmacokinetic profile did not differ from that for the European population. One patient with metastatic esophageal cancer achieved partial response, and each of two patients with non-small cell lung cancer had a minor response.ConclusionsWhen TZT-1027 was administered on days 1 and 8 in 3-week courses to Japanese patients, the MTD was 1.5xa0mg/m2 and was lower than the value of 2.4xa0mg/m2 in European patients. However, antitumor activity was observed at low doses. TZT-1027 was tolerated well at the MTD, without grade 3 nonhematological toxicities or neutropenia up to grade 2. TZT-1027 is a promising new tubulin polymerization inhibitor that requires further investigation in phase II studies.

Ritterazine B, a new cytotoxic natural compound, induces apoptosis in cancer cells

PurposeRitterazinexa0B, one of the ritterazine analogues extracted from Ritterella tokioka, has been shown to be chemically similar to cephalostatin 1, and among the ritterazine derivatives is the most cytotoxic to P388 murine leukemia cells. The objective of this study was to determine the cytotoxicity of ritterazinexa0B to non-small-cell lung cancer (NSCLC) cells in vitro and its effects on the cell cycle and apoptosis.MethodsThe cytotoxicity of ritterazinexa0B against PC14 NSCLC cells was investigated using a 4-day MTT assay. Morphological changes in cells after exposure to this compound were evaluated by phase-contrast microscopy. The effects on the cell cycle of HL-60 leukemia cells and PC14 cells were elucidated by flow cytometry and an in vitro CDK/cyclin kinase assay. Induction of apoptosis in HL-60 cells was assessed using the TUNEL assay and Hoechst 33342 staining. In addition, molecules involved in apoptosis were evaluated by Western blotting.ResultsRitterazinexa0B exerted strong cytotoxic effects against PC14 cells with a mean GI50 of 75.1xa0nM. Cell cycle analysis showed that ritterazinexa0B caused accumulation of HL-60 and PC14 cells at the G2/M checkpoint. Furthermore, ritterazinexa0B-treated HL-60 cells became multinucleated, and at a concentration of 20xa0nM this resulted in the onset of apoptosis. Neither cleavage of caspase target molecules nor phosphorylation of bcl-2 were observed in ritterazinexa0B-treated HL-60 cells.ConclusionsThese results indicate that ritterazinexa0B might be a potent inducer of apoptosis acting via a novel antimitotic mechanism.

Oxaliplatin/fluorouracil/leucovorin (FOLFOX4 and modified FOLFOX6) in patients with refractory or advanced colorectal cancer: post-approval Japanese population experience.

BackgroundThe oxaliplatin/fluorouracil/leucovorin (FOL-FOX regimen) is an effective and generally well-tolerated regimen in Western clinical studies of advanced colorectal cancer. In Japan, oxaliplatin was approved in April 2005.MethodsTo evaluate the objective tumor responses and feasibility (toxicities) of FOLFOX regimens (FOLFOX4 and modified FOLFOX6, mFOLFOX6) in a predominantly Japanese population with refractory or advanced colorectal cancer in Japan, 51 consecutive patients with histologically confirmed metastatic colon or rectum cancer who were treated between April 2005 and March 2006 were enrolled in a retrospective study. FOLFOX4 was used for treatment in 39% (first-line, 45%) of these patients, and mFOLFOX6 was used for treatment in 61% (first-line, 61%). Tumor responses were assessed radiologically, and toxicities were graded according to the Common Terminology Criteria for Adverse Events (CTCAE) version 3.0 regarding toxicities other than peripheral sensory neuropathy.ResultsThe objective response rates (in those who underwent first- or second-line therapy) were 50.0% and 8.7%, respectively. The tumor control rate (partial response [PR] + stable disease [SD]) was 80.4%. There were no toxicity-related deaths. Neutropenia grade 3 was experienced in 20% of patients, and often caused delay in the subsequent treatment course. Mild to moderate cumulative peripheral sensory neuropathy affected 78% of patients. The incidence of hypersensitivity reactions to oxaliplatin in our study was lower than that in reported in Western countries.ConclusionBoth FOLFOX regimens have good efficacy in refractory or advanced colorectal cancer in a Japanese population, with an acceptable overall toxicity profile.

Amrubicin for non-small-cell lung cancer and small-cell lung cancer

SummaryAmrubicin is a totally synthetic anthracycline anticancer drug and a potent topoisomerase II inhibitor. Recently, amrubicin was approved in Japan for the treatment of small- and non-small-cell lung cancers (SCLC and NSCLC). Here, we review the efficacy and toxicities of amrubicin monotherapy and amrubicin in combination with cisplatin for extensive-disease SCLC (ED-SCLC), and of amrubicin monotherapy for advanced NSCLC, as observed in the clinical trials. Recommended dosage for previously untreated advanced NCSLC was 45xa0mg/m2/day by intravenous administration for 3xa0days. Dose-limiting toxicities were leucopenia, thrombocytopenia, and gastrointestinal disturbance. Response rate was 27.9% for advanced NSCLC, and 75.8% for ED-SCLC with a median survival time (MST) of 11.7xa0months. Recommended dosage of amrubicin was 40xa0mg/m2/day in combination with cisplatin at 60xa0mg/m2/day, with MST of 13.6xa0months and 1-year survival rate of 56.1%. In sensitive or refractory relapsed SCLC, response rate was 52 and 50%, progression-free survival was 4.2 and 2.6xa0months, overall survival was 11.6 and 10.3xa0months, and 1-year survival rate was 46 and 40%, respectively. These results are promising for the treatment of both NSCLC and SCLC. Further clinical trials will clarify the status of amrubicin in the treatment of lung cancer.

Recent advances in ideas on the molecular pathology and clinical aspects of Von Hippel-Lindau disease

Von Hippel-Lindau (VHL) disease is an autosomal dominant disorder that is associated with various tumors and cysts in the central nervous system (CNS) and visceral organs. Inactivation of the VHL tumor-suppressor protein and subsequent loss of function in the VHL, and Elongin BC (VBC) complex result in dysfunction in the ubiquitination of hypoxia-inducible factor (HIF), which is an important step in the development of angiogenic tumors. The most frequent disorders in VHL disease are hemangioblastoma in the CNS and retina, pheochromocytoma in the adrenal gland, renal cell carcinoma, and pancreatic neuroendocrine tumor. Here, we review recent ideas on the pathogenesis and clinical diagnosis and treatment of VHL disease. Progress in molecular diagnosis and molecular targeting therapy is expected for improvement in the diagnosis and treatment of this disease. The family’s support for patients with VHL disease is important, being mutually helpful to overcome various social and psychological problems in the patients.

Molecular target-based cancer therapy: tyrosine kinase inhibitors.

Improved understanding of tumor biology has led to the identification of numerous growth factors that are involved in malignant transformation and tumor progression. Many of these factors induce cellular responses through receptors with intrinsic tyrosine kinase (TK) activity. Therefore, inhibiting the activity of TK receptors is one of the ways to effectively block the disordered proliferation of cancer that arises from these pathways. The human epidermal growth factor receptor (HER) family is overexpressed or dysfunctional in many human malignancies. Therefore, these receptors have been identified as targets for cancer therapy. Several agents have been developed that reversibly or irreversibly inhibit one, two, or all of the HER receptors. Iressa and Tarceva are HER1-specific TK inhibitors that are in advanced development. The large phase II study of Iressa (IDEAL1) in patients with non-small-cell lung cancer (NSCLC) in whom previous platinum-based therapy has failed, found that the median survival time (MST) was 7.6 months, which was no less than that with Docetaxel treatment. Other dual or pan-HER, reversible or irreversible, TK inhibitors are being investigated in phase I trials. Early data show that they are generally well tolerated and have provided evidence of against activity tumors. HER-TK inhibitors are likely to have a substantial impact on the treatment of cancer patients.

Phase I/II study of S-1 plus carboplatin in patients with advanced non-small cell lung cancer

The objective of this phase I/II study was to determine the recommended dose (RD) of S-1 and carboplatin (CBDCA), and to evaluate the efficacy and safety of this combination in the treatment of patients with advanced non-small cell lung cancer (NSCLC). Chemotherapy-naïve patients were treated with S-1 given orally on days 1-14, and CBDCA infused intravenously on day 1, repeated every 3 weeks. RD was AUC5 of CBDCA and 80 mg/m(2) of S-1. Nineteen patients were treated at the RD. The overall response was 30.8% (95% confidence interval: 17.1-58.3%). The response rate in the RD was 36.8% (95% CI: 16.3-61.6%). The median overall survival time was 11.1 months (95% CI: 8.1-15.3 months) and the median progression-free survival time was 5.0 months (95% CI: 3.6-6.0 months). Major grades 3-4 toxicities were thrombocytopaenia (47%), anaemia (26%) and infection (16%). This is the first report to show promising activity of this combination in phase II, including survival data and manageable toxicity, especially in outpatients receiving treatment for advanced NSCLC.