HOTAIR and its surrogate DNA methylation signature indicate carboplatin resistance in ovarian cancer.

BACKGROUND: Understanding carboplatin resistance in ovarian cancer is critical for the improvement of patients' lives. Multipotent mesenchymal stem cells or an aggravated epithelial to mesenchymal transition phenotype of a cancer are integrally involved in pathways conferring chemo-resistance. Long non-coding RNA HOTAIR (HOX transcript antisense intergenic RNA) is involved in mesenchymal stem cell fate and cancer biology. METHODS: We analyzed HOTAIR expression and associated surrogate DNA methylation (DNAme) in 134 primary ovarian cancer cases (63 received carboplatin, 55 received cisplatin and 16 no chemotherapy). We validated our findings by HOTAIR expression and DNAme analysis in a multicentre setting of five additional sets, encompassing 946 ovarian cancers. Chemo-sensitivity has been assessed in cell culture experiments. RESULTS: HOTAIR expression was significantly associated with poor survival in carboplatin-treated patients with adjusted hazard ratios for death of 3.64 (95 % confidence interval [CI] 1.78-7.42; P < 0.001) in the discovery and 1.63 (95 % CI 1.04-2.56; P = 0.032) in the validation set. This effect was not seen in patients who did not receive carboplatin (0.97 [95 % CI 0.52-1.80; P = 0.932]). HOTAIR expression or its surrogate DNAme signature predicted poor outcome in all additional sets of carboplatin-treated ovarian cancer patients while HOTAIR expressors responded preferentially to cisplatin (multivariate interaction P = 0.008). CONCLUSIONS: Non-coding RNA HOTAIR or its more stable DNAme surrogate may indicate the presence of a subset of cells which confer resistance to carboplatin and can serve as (1) a marker to personalise treatment and (2) a novel target to overcome carboplatin resistance.

Vorinostat in patients with advanced malignant pleural mesothelioma who have progressed on previous chemotherapy (VANTAGE-014): a phase 3, double-blind, randomised, placebo-controlled trial.

BACKGROUND: Vorinostat is a histone deacetylase inhibitor that changes gene expression and protein activity. On the basis of the clinical benefit reported in patients with malignant pleural mesothelioma treated in a phase 1 study of vorinostat, we designed this phase 3 trial to investigate whether vorinostat given as a second-line or third-line therapy improved patients' overall survival. METHODS: This double-blind, randomised, placebo-controlled trial was done in 90 international centres. Patients with measurable advanced malignant pleural mesothelioma and disease progression after one or two previous systemic regimens were eligible. After stratification for Karnofsky performance status, histology, and number of previous chemotherapy regimens, patients were randomly assigned (1:1) by use of an interactive voice response system with a block size of four to either treatment with vorinostat or placebo. Patients received oral vorinostat 300 mg (or matching placebo) twice daily on days 1, 2, 3, 8, 9, 10, 15, 16, and 17 of a 21-day cycle. The primary endpoints were overall survival and safety and tolerability of vorinostat. The primary efficacy comparison was done in the intention-to-treat population, and safety and tolerability was assessed in the treated population. This trial is registered with ClinicalTrials.gov, number NCT00128102. FINDINGS: From July 12, 2005, to Feb 14, 2011, 661 patients were enrolled and randomly assigned to receive either vorinostat (n=329) or placebo (n=332) and included in the intention-to-treat analysis. Median overall survival for vorinostat was 30·7 weeks (95% CI 26·7-36·1) versus 27·1 weeks (23·1-31·9) for placebo (hazard ratio 0·98, 95% CI 0·83-1·17, p=0·86). The most common grade 3 or worse adverse events for patients treated with vorinostat were fatigue or malaise (51 [16%] patients in the vorinostat group vs 25 [8%] in the placebo group]) and dyspnoea (35 [11%] vs 45 [14%]). INTERPRETATION: In this randomised trial, vorinostat given as a second-line or third-line therapy did not improve overall survival and cannot be recommended as a therapy for patients with advanced malignant pleural mesothelioma. FUNDING: Merck & Co.

Effect of erlotinib on CYP3A activity, evaluated in vitro and by dual probes in patients with cancer.

In vitro, erlotinib (0-30 µmol/l) and C-labelled midazolam (MDZ) (5 µmol/l) were incubated with human liver microsomes; separately, microsomes were preincubated with erlotinib (10 µmol/l) before the addition of MDZ. Results showed a time-dependent inhibition of MDZ metabolism by erlotinib, with a Ki of 7.5 µmol/l and an inactivation rate constant of 0.009/min. Patients with cancer (n=24) received a single oral dose of 7.5 mg MDZ and a single intravenous dose of 3 µCi [C-N-methyl] erythromycin on days 1, 8, 14 and 21. Patients also received 150 mg oral erlotinib daily from day 8 to day 14. Plasma concentrations of erlotinib and OSI-420 were determined on days 8 and 14; MDZ and 1'-hydroxymidazolam were determined on days 1, 8, 14 and 21. Coadministration of erlotinib resulted in a 4 and a 16% increase in CO2 on days 8 and 14, respectively, after the administration of erythromycin. The mean AUC0-last of MDZ decreased 17 and 34% after erlotinib treatment on day 8 and day 14, respectively. The half-life of MDZ and the AUC ratio of 1'-hydroxymidazolam to MDZ were not significantly changed. Although erlotinib may be a weak mechanism-based irreversible inhibitor of CYP3A4 in vitro, in vivo, erlotinib did not inhibit CYP3A-mediated metabolism, as determined by the erythromycin breath test and the MDZ pharmacokinetics. The mechanism for reduced exposure of MDZ is unclear, but may be because of an increase in intestinal metabolism or decreased absorption. These findings suggest that coadministration of erlotinib may not result in clinically relevant increases in exposure of CYP3A substrates.

A phase II study of the potent PARP inhibitor, Rucaparib (PF-01367338, AG014699), with temozolomide in patients with metastatic melanoma demonstrating evidence of chemopotentiation.

PURPOSE: poly(ADP ribose) polymerase inhibition has been shown to potentiate the cytotoxicity of DNA damaging agents. A phase I study of rucaparib and temozolomide showed that full-dose temozolomide could be given during PARP inhibition. We report the results of a phase II study of intravenous rucaparib 12 mg/m(2) and oral temozolomide 200 mg/m(2) on days 1-5 every 28 days in patients with advanced metastatic melanoma. METHODS: Patients with chemotherapy naïve measurable metastatic melanoma, performance status ≤2 and good end-organ function were recruited. Treatment was given until progression. A two stage phase II design was used, with response rate the primary endpoint. Population pharmacokinetics and pharmacodynamics were also explored. RESULTS: Forty-six patients were recruited with 37 patients receiving at least 2 cycles and 17 patients at least 6 cycles. Myelosuppression occurred with 25 patients (54 %) requiring a 25 % dose reduction in temozolomide. The response rate was 17.4 %, median time to progression 3.5 months, median overall survival 9.9 months, and 36 % of patients were progression-free at 6 months. CONCLUSIONS: This study showed that temozolomide (150-200 mg/m(2)/day) can safely be given with a PARP inhibitory dose of rucaparib, increasing progression-free survival over historical controls in metastatic melanoma patients.

Phase I study of PM00104 (Zalypsis®) administered as a 1-hour weekly infusion resting every fourth week in patients with advanced solid tumors.

PM00104 (Zalypsis®) is a new synthetic alkaloid with potent cytotoxic activity against tumor cell lines. This phase I clinical trial determined the maximal tolerated dose (MTD) and recommended dose (RD) for phase II trials of PM00104 administered as a 1-hour intravenous (i.v.) infusion weekly for three consecutive weeks resting every fourth week (d1,8,15 q4wk). Forty-nine patients with advanced solid malignancies received PM00104 following a toxicity-guided, accelerated, dose-escalation design. Doses evaluated ranged from 0.07 to 3.0 mg/m(2). Dose-limiting toxicities (DLTs) appeared at the highest doses tested and comprised grade 3 diarrhea and grade 4 lipase increase at 2.0 mg/m(2); grade 1 thrombocytopenia and grade 2 neutropenia with two infusion omissions, grade 3 fatigue and grade 4 febrile neutropenia at 2.5 mg/m(2); and grade 3/4 fatigue, grade 4 neutropenia lasting >5 days and grade 4 thrombocytopenia at 3.0 mg/m(2). RD was established at 2.0 mg/m(2). PM00104-related adverse events at the RD were mostly grade 1/2, with fatigue, nausea and vomiting as the most common. Transient and manageable myelosuppression and transaminase increases were also reported. Main pharmacokinetic parameters increased linearly with dose. Disease stabilization lasting ≥ 3 months was found in 4 patients with cervical carcinoma, colorectal adenocarcinoma, lachrymal adenoid carcinoma, and bladder carcinoma (n=1 each). In conclusion, PM00104 2.0 mg/m(2) 1-hour, d1,8,15 q4wk showed a positive risk-benefit ratio, which has supported its further evaluation in three ongoing phase II clinical trials.

Targeted agents: how to select the winners in preclinical and early clinical studies?

There has been a significant shift within oncology drug development away from empiric screening of cytotoxic compounds to the era of genomics and molecularly targeted agents. The drug development process is evolving with greater emphasis on proof-of-mechanism studies in both preclinical and early clinical development. The Methodology for the Development of Innovative Cancer Therapies (MDICT) Task Force, established as a forum for academic and pharmaceutical leaders to discuss methodological issues in targeted anticancer therapy development, met in March 2010 to review what were the minimal data required to make appropriate decisions about moving new targeted cancer agents from late preclinical development into phase I and from phase I into phase II trials. A number of specific questions were posed, and responses to each developed through survey, literature review and discussion at the face to face meeting of the MDICT Task Force. Consensus emerged around the necessity to demonstrate proof-of-mechanism and obtain information on key pharmacokinetic aspects of drug behaviour in late preclinical and early clinical trials. However, controversy remains on the extent of in vivo anti-tumour efficacy required to support clinical development of targeted agents. A systematic review of the data in this area would be informative. Further, while objective response in phase I trials may be a favourable signal about the potential activity of a new agent, debate exists around the weight that should be placed on the observation of stable disease or functional imaging changes in driving drug development decisions in the absence of observing either responses or convincing pharmacodynamic data in phase I. MDICT made a number of recommendations that may aid in future development of targeted agents.

Phase I trial of the irreversible EGFR and HER2 kinase inhibitor BIBW 2992 in patients with advanced solid tumors.

PURPOSE: Preclinical data have demonstrated that BIBW 2992 is a potent irreversible inhibitor of ErbB1 (EGFR/HER1) and mutated ErbB1 receptors including the T790M variant, as well as ErbB2 (HER2). A phase I study of continuous once-daily oral BIBW 2992 was conducted to determine safety, maximum-tolerated dose, pharmacokinetics (PK), food effect, and preliminary antitumor efficacy. PATIENTS AND METHODS: Patients with advanced solid tumors were treated. PK evaluation was performed after the first dose and at steady-state. RESULTS: Fifty-three patients received BIBW 2992 at 10 to 50 mg/d. BIBW 2992 was generally well-tolerated. The most common adverse effects included diarrhea, nausea, vomiting, rash, and fatigue. Dose-limiting toxicities included grade 3 rash (n = 2) and reversible dyspnea secondary to pneumonitis (n = 1). The recommended phase II dose was 50 mg/d. PK was dose proportional with a terminal elimination half-life ranging between 21.3 and 27.7 hours on day 1 and between 22.3 and 67.0 hours on day 27; BIBW 2992 exposure decreased after food intake. Three patients with non-small-cell lung carcinoma (NSCLC; two with in-frame exon 19 mutation deletions) experienced confirmed partial responses (PR) sustained for 24, 18, and 34 months, respectively. Two other patients (esophageal carcinoma and NSCLC) had nonconfirmed PRs. A patient with a PR at 10 mg/d progressed and developed symptomatic brain metastases, which subsequently regressed with an increased dose of 40 mg/d of BIBW 2992. A further seven patients had disease stabilization lasting > or = 6 months. CONCLUSION: Continuous, daily, oral BIBW 2992 is safe and has durable antitumor activity. It is currently being evaluated in phase III trials.

Performing phase I clinical trials of anticancer agents: perspectives from within the European union and Japan.

Drug discovery and early clinical development is an international endeavor, conducted in partnership between commercial entities such as biotechnology and pharmaceutical companies and academic investigators. Although once considered quite disparate, early clinical trials requirements and conduct are largely harmonized between the European Union, Japan, and the United States, increasing the opportunities for productive commercial-academic collaborations.

A monoclonal antibody for detection of folylpolyglutamate synthetase in paraffin embedded tissues.

Folate biochemical pathway enzymes such as folylpolyglutamate synthetase (FPGS) are key elements in the folate pathway. The role of FPGS is to add glutamate residues to folates and antifolates, trapping them in the cell and increasing their affinity for subsequent enzymatic reactions. FPGS may also be an indicator of response to both clinically established and novel antifolate drugs such as pemetrexed; knowledge of their level of expression in tumors may enable their optimal use by identifying potentially responsive subgroups of patients. In spite of its key role in both nucleotide biosynthesis and possible role as a determinant of response in chemotherapy, monoclonal antibodies to FPGS suitable for immunohistochemical analysis of formalin fixed and paraffin embedded biopsy samples, or that can be used for Western blot analysis, are not commercially available. The aim of this study was to generate a monoclonal antibody that could be used to detect specific expression of FPGS in paraffin embedded tissues. A 228 amino acid region of the FPGS sequence was expressed as a recombinant fusion protein and used as an antigen to generate monoclonal antibodies. ELISA and Western blot studies identified specific reactivity of the NN3.2 antibody to the recombinant protein and a single 60 kDa protein in whole cell lysates from cell lines known to express FPGS. Immunohistochemical analysis of FPGS using hybridoma clone NN3.2 in a panel of normal tissues demonstrated wide expression including strong immunoreactivity in the brush border and crypts of colon, liver hepatocytes, and lymphoid cells. Analysis of a panel of malignant and benign tissues demonstrated wide expression with variable intensities of staining and patterns of cytoplasmic reactivity. Stronger staining was observed in malignant tissue compared with that of normal adjacent tissue, particularly in ovarian and colon adenocarcinoma cases. Our results show that clone NN3.2 is a sensitive tool for detection of FPGS in paraffin-embedded tissues.

Phase II studies of polymer-doxorubicin (PK1, FCE28068) in the treatment of breast, lung and colorectal cancer.

Phase I studies of [N-(2-hydroxypropyl)methacrylamide] (HPMA) copolymer-doxorubicin previously showed signs of activity coupled with 5-fold decreased anthracycline toxicity in chemotherapy-refractory patients. Here we report phase II studies using a similar material (FCE28068) in patients with breast (n=17), non-small cell lung (NSCLC, n=29) and colorectal (n=16) cancer. Up to 8 courses of PK1 (280 mg/m(2) doxorubicin-equivalent) were given i.v., together with 123I-labelled imaging analogue. Toxicities were tolerable, with grade 3 neutropenia more prominent in patients with breast cancer (4/17, 23.5% compared with 5/62, 8.1% overall). Of 14 evaluable patients with breast cancer 3 had partial responses (PR), all anthracycline-naïve patients. In 26 evaluable patients with NSCLC, 3 chemotherapy-naïve patients had PR. In contrast, none of the 16 evaluable patients with colorectal cancer responded. Imaging of 16 patients (5 with breast cancer, 6 NSCLC, 5 colorectal cancer) showed obvious tumour accumulation in 2 metastatic breast cancers, although unfortunately no images were obtained from patients who responded. These results show 6/62 PR with limited side effects, supporting the concept that polymer-bound therapeutics can have modified and improved anticancer activities and suggesting the approach should be explored further for breast cancer and NSCLC.

Phase I study of MG98, an oligonucleotide antisense inhibitor of human DNA methyltransferase 1, given as a 7-day infusion in patients with advanced solid tumors.

PURPOSE: To assess the safety and tolerability, pharmacokinetics, and early evidence of antitumor activity of escalating doses of MG98, an antisense oligonucleotide to DNA methyltransferase 1 (DNMT1), which has been shown to reduce CpG island methylation and allow reexpression of tumor suppressor genes in vitro. EXPERIMENTAL DESIGN: In this phase I, open-label study, patients with advanced solid malignancies were treated with escalating doses of MG98 administered as a continuous i.v. infusion over 7 days repeated every 14 days. Cohorts of three patients, which could be expanded to six patients, were studied. The maximum tolerated dose was defined as the highest dose at which no more than 33% of subjects experienced dose-limiting toxicity. Pharmacokinetic and pharmacodynamic parameters of MG98 were also characterized. RESULTS: Thirty-three patients were treated at doses of 100 to 250 mg/m(2)/d MG98. MG98 was well tolerated with mild fatigue and myalgia, dose-limiting toxicity was asymptomatic transaminitis, and the maximum tolerated dose was 200 mg/m(2)/d. One patient achieved a partial response and another prolonged disease stabilization. Plasma half-life of MG98 was short (2 hours), drug concentrations reaching a dose-dependent steady state during infusion with a volume of distribution equivalent to plasma volume. Suppression of DNMT1 expression was observed in 26 of 32 patients studied. CONCLUSIONS: MG98 was well tolerated with early evidence of clinical activity. Proof of mechanism was observed and measurement of DNMT1 expression in peripheral blood mononuclear cells may be useful in future phase II development.

A randomised, double-blind, phase II study of two doses of pemetrexed in the treatment of platinum-resistant, epithelial ovarian or primary peritoneal cancer.

PURPOSE: We conducted a randomised phase II study to assess the safety and efficacy of standard versus high-dose pemetrexed in platinum-resistant epithelial ovarian cancer (PR-EOC). The expression of ten genes was also examined as potential biomarkers of pemetrexed/platinum activity. PATIENTS AND METHODS: Patients received pemetrexed 500mg/m(2) (Pem500) or 900mg/m(2) (Pem900) on day 1 of each 21-d cycle. Responses were defined per RECIST for measurable disease or by Gynaecologic Cancer Intergroup (GCIG) CA-125 criteria for non-measurable disease. RESULTS: Of 102 patients randomised, 98 were evaluable for toxicity (47 Pem500, 51 Pem900) and 91 were evaluable for efficacy (43 Pem500, 48 Pem900) of whom 68 had measurable disease and 23 had CA-125-defined disease. The overall RR was 9.3% (95% CI: 2.6-22.1%) on Pem500 and 10.4% (95% CI: 3.5-22.7%) on Pem900. The median progression-free survival (PFS) was 2.8 months on both arms, and the median survival was 11.9 and 10.3 months, respectively. Lower mRNA expression of excision repair cross-complementation group 1 (ERCC1) and reduced folate carrier 1 (RFC1) were associated with longer PFS and time to treatment failure, respectively. Grade 3/4 toxicities, including fatigue, nausea and vomiting, were numerically greater on Pem900. Pemetrexed-related SAEs occurred in 17% and 28% of Pem500 and Pem900 patients, respectively. CONCLUSIONS: Pemetrexed has activity in PR-EOC equivalent to other agents in platinum-resistant disease; however, Pem500 has the preferable toxicity profile. ERCC1 and RFC1 may merit examination as predictive biomarkers in PR-EOC.

Phase I study of the poly(ADP-ribose) polymerase inhibitor, AG014699, in combination with temozolomide in patients with advanced solid tumors.

PURPOSE: One mechanism of tumor resistance to cytotoxic therapy is repair of damaged DNA. Poly(ADP-ribose) polymerase (PARP)-1 is a nuclear enzyme involved in base excision repair, one of the five major repair pathways. PARP inhibitors are emerging as a new class of agents that can potentiate chemotherapy and radiotherapy. The article reports safety, efficacy, pharmacokinetic, and pharmacodynamic results of the first-in-class trial of a PARP inhibitor, AG014699, combined with temozolomide in adults with advanced malignancy. EXPERIMENTAL DESIGN: Initially, patients with solid tumors received escalating doses of AG014699 with 100 mg/m2/d temozolomide x 5 every 28 days to establish the PARP inhibitory dose (PID). Subsequently, AG014699 dose was fixed at PID and temozolomide escalated to maximum tolerated dose or 200 mg/m2 in metastatic melanoma patients whose tumors were biopsied. AG014699 and temozolomide pharmacokinetics, PARP activity, DNA strand single-strand breaks, response, and toxicity were evaluated. RESULTS: Thirty-three patients were enrolled. PARP inhibition was seen at all doses; PID was 12 mg/m2 based on 74% to 97% inhibition of peripheral blood lymphocyte PARP activity. Recommended doses were 12 mg/m2 AG014699 and 200 mg/m2 temozolomide. Mean tumor PARP inhibition at 5 h was 92% (range, 46-97%). No toxicity attributable to AG014699 alone was observed. AG014699 showed linear pharmacokinetics with no interaction with temozolomide. All patients treated at PID showed increases in DNA single-strand breaks and encouraging evidence of activity was seen. CONCLUSIONS: The combination of AG014699 and temozolomide is well tolerated, pharmacodynamic assessments showing proof of principle of the mode of action of this new class of agents.

The potential of PARP inhibitors in genetic breast and ovarian cancers.

The abundant nuclear enzyme poly(ADP-ribose) polymerase-1 (PARP-1), represents an important novel target in cancer therapy. PARP-1 is essential to the repair of DNA single-strand breaks via the base excision repair pathway. Inhibitors of PARP-1 have been shown to enhance the cytotoxic effects of ionizing radiation and DNA damaging chemotherapy agents, such as the methylating agents and topoisomerase I inhibitors. There are currently at least five PARP inhibitors in clinical trial development. Recent in vitro and in vivo evidence suggests that PARP inhibitors could be used not only as chemo/radiotherapy sensitizers, but as single agents to selectively kill cancers defective in DNA repair, specifically cancers with mutations in the breast cancer associated (BRCA) 1 and 2 genes. This theory of selectively exploiting cells defective in one DNA repair pathway by inhibiting another is a major breakthrough in the treatment of cancer. BRCA1/2 mutations are responsible for the majority of genetic breast/ovarian cancers, known as the hereditary breast ovarian cancer syndrome. This review summarizes the preclinical and clinical evidence for the potential of PARP inhibitors in genetic breast and ovarian cancers.

Open-label, non-randomised, inter-individual dose escalation of ZK 304709 with the evaluation of safety, tolerability, pharmacokinetics, oral bioavailability and orientating efficacy after daily administration in patients with advanced cancer (7 d treatment and 14 d recovery).

PURPOSE: The primary objectives of this study were to determine the maximum tolerated dose (MTD) and dose-limiting toxicities (DLTs) of ZK 304709, a novel multi-targeted growth inhibitor (MTGI(trade mark)), in man. Secondary end-points included safety evaluation, tolerability, pharmacokinetic profiling and assessment of response using standard and novel surrogate pharmacodynamic end-points. MATERIALS AND METHODS: Patients (n=40) with advanced solid malignancies were treated with ZK 304709, administered orally once daily for 7 d with 14 d recovery. Doses were escalated in sequential cohorts of three patients with expansion to 6-7 patients should a dose-limiting toxicity occur. RESULTS: ZK 304709 was safely administered up to 360mg. However, above 90mg blood concentrations increased only slightly. As this dose was not deemed likely to result in meaningful pharmacologic or clinical activity, the trial was stopped before the MTD was ascertained. It was therefore not possible to make a reliable assessment of efficacy or pharmacodynamic end-points. CONCLUSIONS: Due to the lack of further increment in blood concentrations above a dose of 90mg, which was felt from previous animal studies to be unlikely to result in meaningful pharmacologic or clinical activity, this study was stopped early.

Mechanisms of chemoresistance to alkylating agents in malignant glioma.

Intrinsic or acquired chemoresistance to alkylating agents is a major cause of treatment failure in patients with malignant brain tumors. Alkylating agents, the mainstay of treatment for brain tumors, damage the DNA and induce apoptosis, but the cytotoxic activity of these agents is dependent on DNA repair pathways. For example, O6-methylguanine DNA adducts can cause double-strand breaks, but this is dependent on a functional mismatch repair pathway. Thus, tumor cell lines deficient in mismatch repair are resistant to alkylating agents. Perhaps the most important mechanism of resistance to alkylating agents is the DNA repair enzyme O6-methylguanine methyltransferase, which can eliminate the cytotoxic O6-methylguanine DNA adduct before it causes harm. Another mechanism of resistance to alkylating agents is the base excision repair (BER) pathway. Consequently, efforts are ongoing to develop effective inhibitors of BER. Poly(ADP-ribose)polymerase plays a pivotal role in BER and is an important therapeutic target. Developing effective strategies to overcome chemoresistance requires the identification of reliable preclinical models that recapitulate human disease and which can be used to facilitate drug development. This article describes the diverse mechanisms of chemoresistance operating in malignant glioma and efforts to develop reliable preclinical models and novel pharmacologic approaches to overcome resistance to alkylating agents.

Targeting poly(ADP-ribose) polymerase: a two-armed strategy for cancer therapy.

The DNA repair pathways are protective of the host genome in normal cells; however, in cancer cells, these pathways may be disrupted and predispose to tumorigenesis or their activity may overcome the potentially cytotoxic damage caused by anticancer agents and be a mechanism of resistance. Poly(ADP-ribose) polymerase inhibitors, which block base excision repair of single-strand breaks, have entered the clinic in the last few years. This article discusses the interactions between the pathways of single- and double-strand break repair, which explain the two clinical development strategies for this class of drugs.

Population pharmacokinetics and pharmacodynamics of paclitaxel and carboplatin in ovarian cancer patients: a study by the European organization for research and treatment of cancer-pharmacology and molecular mechanisms group and new drug development group.

PURPOSE: Paclitaxel and carboplatin are frequently used in advanced ovarian cancer following cytoreductive surgery. Threshold models have been used to predict paclitaxel pharmacokinetic-pharmacodynamics, whereas the time above paclitaxel plasma concentration of 0.05 to 0.2 micromol/L (t(C > 0.05-0.2)) predicts neutropenia. The objective of this study was to build a population pharmacokinetic-pharmacodynamic model of paclitaxel/carboplatin in ovarian cancer patients. EXPERIMENTAL DESIGN: One hundred thirty-nine ovarian cancer patients received paclitaxel (175 mg/m(2)) over 3 h followed by carboplatin area under the concentration-time curve 5 mg/mL*min over 30 min. Plasma concentration-time data were measured, and data were processed using nonlinear mixed-effect modeling. Semiphysiologic models with linear or sigmoidal maximum response and threshold models were adapted to the data. RESULTS: One hundred five patients had complete pharmacokinetic and toxicity data. In 34 patients with measurable disease, objective response rate was 76%. Neutrophil and thrombocyte counts were adequately described by an inhibitory linear response model. Paclitaxel t(C > 0.05) was significantly higher in patients with a complete (91.8 h) or partial (76.3 h) response compared with patients with progressive disease (31.5 h; P = 0.02 and 0.05, respectively). Patients with paclitaxel t(C > 0.05) > 61.4 h (mean value) had a longer time to disease progression compared with patients with paclitaxel t(C > 0.05) < 61.4 h (89.0 versus 61.9 weeks; P = 0.05). Paclitaxel t(C > 0.05) was a good predictor for severe neutropenia (P = 0.01), whereas carboplatin exposure (C(max) and area under the concentration-time curve) was the best predictor for thrombocytopenia (P < 10(-4)). CONCLUSIONS: In this group of patients, paclitaxel t(C > 0.05) is a good predictive marker for severe neutropenia and clinical outcome, whereas carboplatin exposure is a good predictive marker for thrombocytopenia.

A novel monoclonal antibody for detection of folate receptor alpha in paraffin-embedded tissues.

Folate biochemical pathway components such as FR-alpha are determinants of response to novel antifolate drugs such as pemetrexed. Knowledge of their level of expression in tumors will enable their optimal use by identifying potentially responsive subgroups of patients. In spite of its importance in the diagnosis and treatment of cancer, monoclonal antibodies to FR-alpha suitable for immunohistochemical analysis of formalin-fixed and paraffin-embedded biopsy samples, or that can be used for Western blot analysis, are not available. The aim of this study was thus to generate a monoclonal antibody that could be used to detect specific expression of FR-alpha in paraffin-embedded tissues. A 189 amino acid region of the FR-alpha sequence was expressed as a recombinant fusion protein and used as antigen to generate monoclonal antibodies. Studies by ELISA and Western blot identified specific reactivity of the BN3.2 antibody to the recombinant protein and a single 40 kD protein in whole cell lysates from cell lines known to express FR-alpha. Immunohistochemical analysis of FR-alpha using hybridoma clone BN3.2 in a panel of normal tissues demonstrated expression limited to ovarian epithelia, placental trophoblasts, and proximal kidney tubules. Analysis of a panel of malignant and benign tissues demonstrated limited expression with variable intensities of staining and patterns of both membrane and cytoplasmic reactivity observed between cases. In the majority of malignant ovarian tumors, high intensity staining was observed, predominantly localized to the plasma membrane. Our results show that clone BN3.2 is a sensitive tool for detection of FR-alpha in paraffin-embedded tissues. This preliminary study also supports its use in immunohistochemical studies to determine the role of FR-alpha as a tumor prognostic marker and a possible therapeutic target.

Phase 1 and pharmacokinetic study of lexatumumab in patients with advanced cancers.

PURPOSE: To assess the safety and tolerability, pharmacokinetics, and early evidence of antitumor activity of escalating doses of lexatumumab (HGS-ETR2), a fully human agonistic monoclonal antibody which targets and activates the tumor necrosis factor-related apoptosis-inducing ligand receptor 2 (TRAIL-R2) in patients with advanced solid malignancies. EXPERIMENTAL DESIGN: In this phase 1, open label study, patients with advanced solid malignancies were treated with escalating doses of lexatumumab administered i.v. over 30 to 120 min every 21 days. A cohort of four patients, which could be expanded to six patients, was studied at each dose level. The dose-limiting toxicity (DLT) dose was defined as the dose at which the incidence of DLT in the first two cycles was >or=33%. The maximum tolerated dose was defined as the highest dose at which <33% of subjects experienced DLT. The pharmacokinetics and immunogenicity of lexatumumab were also characterized. Tumor specimens from historical or current biopsies, when available, were stained for TRAIL-R2 using immunohistochemistry techniques. RESULTS: Thirty-seven patients received 120 cycles of lexatumumab at doses ranging from 0.1 to 20 mg/kg every 21 days as of May 2006. The 20 mg/kg dose was identified as the DLT dose based on DLTs in three of seven patients treated with this dose; DLTs included asymptomatic elevations of serum amylase, transaminases, and bilirubin. The 10 mg/kg dose cohort was expanded to 12 patients and the 10 mg/kg dose was identified as the maximum tolerated dose. The mean (+/-SD) clearance and apparent terminal half-life values at the 10 mg/kg dose averaged 6.0 (2.9) mL/d/kg and 16.4 (10.9) days, respectively. Twelve patients had durable stable disease that lasted a median of 4.5 months, including three patients with sarcoma having prolonged stable disease (>or=6.7 months). Immunohistochemistry for TRAIL-R2 showed specific staining in >10% of tumor cells for 16 of the 20 evaluable specimens submitted (80%). CONCLUSIONS: Lexatumumab was safe and well tolerated at doses up to and including 10 mg/kg every 21 days. Lexatumumab was associated with sustained stable disease in several patients. Pharmacokinetics were linear over the dose range studied, and consistent with a two-compartment model with first-order elimination from the central compartment. Additional evaluation of this novel apoptosis-inducing agent, particularly in combination with chemotherapy agents, is warranted and ongoing.