Effective ribosomal RNA depletion for single-cell total RNA-seq by scDASH.

A decade since its invention, single-cell RNA sequencing (scRNA-seq) has become a mainstay technology for profiling transcriptional heterogeneity in individual cells. Yet, most existing scRNA-seq methods capture only polyadenylated mRNA to avoid the cost of sequencing non-messenger transcripts, such as ribosomal RNA (rRNA), that are usually not of-interest. Hence, there are not very many protocols that enable single-cell analysis of total RNA. We adapted a method called DASH (Depletion of Abundant Sequences by Hybridisation) to make it suitable for depleting rRNA sequences from single-cell total RNA-seq libraries. Our analyses show that our single-cell DASH (scDASH) method can effectively deplete rRNAs from sequencing libraries with minimal off-target non-specificity. Importantly, as a result of depleting the rRNA, the rest of the transcriptome is significantly enriched for detection.

Paclitaxel with or without trametinib or pazopanib in advanced wild-type BRAF melanoma (PACMEL): a multicentre, open-label, randomised, controlled phase II trial.

BACKGROUND: Advanced melanoma treatments often rely on immunotherapy or targeting mutations, with few treatment options for wild-type BRAF (BRAF-wt) melanoma. However, the mitogen-activated protein kinase pathway is activated in most melanoma, including BRAF-wt. We assessed whether inhibiting this pathway by adding kinase inhibitors trametinib or pazopanib to paclitaxel chemotherapy improved outcomes in patients with advanced BRAF-wt melanoma in a phase II, randomised and open-label trial. PATIENTS AND METHODS: Patients were randomised (1 : 1 : 1) to paclitaxel alone or with trametinib or pazopanib. Paclitaxel was given for a maximum of six cycles, while 2 mg trametinib and 800 mg pazopanib were administered orally once daily until disease progression or unacceptable toxicity. Participants and investigators were unblinded. The primary end point was progression-free survival (PFS). Key secondary end points included overall survival (OS) and objective response rate (ORR). RESULTS: Participants were randomised to paclitaxel alone (n = 38), paclitaxel and trametinib (n = 36), or paclitaxel and pazopanib (n = 37). Adding trametinib significantly improved 6-month PFS [time ratio (TR), 1.47; 90% confidence interval (CI) 1.08-2.01, P = 0.04] and ORR (42% versus 13%; P = 0.01) but had no effect on OS (P = 0.25). Adding pazopanib did not benefit 6-month PFS; (TR 1.36; 90% CI 0.96-1.93; P = 0.14), ORR, or OS. Toxicity increased in both combination arms. CONCLUSION: In this phase II trial, adding trametinib to paclitaxel chemotherapy for BRAF-wt melanoma improved PFS and substantially increased ORR but did not impact OS.This study was registered with the EU Clinical Trials Register, EudraCT number 2011-002545-35, and with the ISRCTN registry, number 43327231.

Adjuvant bevacizumab for melanoma patients at high risk of recurrence: survival analysis of the AVAST-M trial.

Background: Bevacizumab is a recombinant humanised monoclonal antibody to vascular endothelial growth factor shown to improve survival in advanced solid cancers. We evaluated the role of adjuvant bevacizumab in melanoma patients at high risk of recurrence. Patients and methods: Patients with resected AJCC stage IIB, IIC and III cutaneous melanoma were randomised to receive either adjuvant bevacizumab (7.5 mg/kg i.v. 3 weekly for 1 year) or standard observation. The primary end point was detection of an 8% difference in 5-year overall survival (OS) rate; secondary end points included disease-free interval (DFI) and distant metastasis-free interval (DMFI). Tumour and blood were analysed for prognostic and predictive markers. Results: Patients (n=1343) recruited between 2007 and 2012 were predominantly stage III (73%), with median age 56 years (range 18-88 years). With 6.4-year median follow-up, 515 (38%) patients had died [254 (38%) bevacizumab; 261 (39%) observation]; 707 (53%) patients had disease recurrence [336 (50%) bevacizumab, 371 (55%) observation]. OS at 5 years was 64% for both groups [hazard ratio (HR) 0.98; 95% confidence interval (CI) 0.82-1.16, P = 0.78). At 5 years, 51% were disease free on bevacizumab versus 45% on observation (HR 0.85; 95% CI 0.74-0.99, P = 0.03), 58% were distant metastasis free on bevacizumab versus 54% on observation (HR 0.91; 95% CI 0.78-1.07, P = 0.25). Forty four percent of 682 melanomas assessed had a BRAFV600 mutation. In the observation arm, BRAF mutant patients had a trend towards poorer OS compared with BRAF wild-type patients (P = 0.06). BRAF mutation positivity trended towards better OS with bevacizumab (P = 0.21). Conclusions: Adjuvant bevacizumab after resection of high-risk melanoma improves DFI, but not OS. BRAF mutation status may predict for poorer OS untreated and potential benefit from bevacizumab. Clinical Trial Information: ISRCTN 81261306; EudraCT Number: 2006-005505-64.

Assessment of neuronal autoantibodies in patients with small cell lung cancer treated with chemotherapy with or without ipilimumab.

Small-cell lung cancer (SCLC) is often associated with paraneoplastic syndromes. To assess the role of anti-neuronal autoantibodies (NAAs) as biomarkers of treatment outcome, we assessed NAAs in serial samples from SCLC patients treated with chemoimmunotherapy compared to chemotherapy alone. We evaluated 2 cohorts: in cohort 1 (C1), 47 patients received standard platinum/etoposide, and in cohort 2 (C2), 38 patients received ipilimumab, carboplatin and etoposide. Serum samples at baseline and subsequent time points were analyzed for the presence of NAAs. NAAs were detected at baseline in 25 patients (53.2%) in C1 and in 20 patients (52.6%) in C2 (most frequently anti-Sox1). NAA at baseline was associated with limited disease (75% vs 50%; p: 0.096) and better overall survival (15.1 m vs 11.7 m; p: 0.032) in C1. Thirteen patients (28.9%) showed 2 or more reactivities before treatment; this was associated with worse PFS (5.5 m vs 7.3 m; p: 0.005) in patients treated with chemoimmunotherapy. NAA titers decreased after therapy in 68.9% patients, with no differential patterns of change between cohorts. Patients whose NAA titer decreased after treatment, showed longer OS [18.5 m (95% CI: 15.8 - 21.2)] compared with those whose NAA increased [12.3 m (95% CI: 8.1 - 16.5; p 0.049)], suggesting that antibody levels correlate to tumor load. Our findings reinforce the role of NAAs as prognostic markers and tumor activity/burden in SCLC, warrant further investigation in their predictive role for immunotherapy and raise concern over the use of immunotherapy in patients with more than one anti-NAA reactivity.

Quality of life, support and smoking in advanced lung cancer patients: a qualitative study.

BACKGROUND: Lung cancer is the most common cancer and smoking is the principal cause. Due to poor survival rates, symptom palliation and promotion of health-related quality of life (HRQoL) are primary outcomes for lung cancer patients. Given the established relationship between smoking and lung cancer, patients who have smoked may feel stigmatised or guilty after diagnosis, and more pessimistic about their illness and likely outcomes. This may have adverse implications for HRQoL. OBJECTIVES: We explored HRQoL and support experiences among newly diagnosed patients with advanced lung cancer. DESIGN: Semistructured interviews were conducted with nine patients and analysed using interpretative phenomenological analysis. RESULTS: Patients described the physical, emotional and social impact of disease on HRQoL. Fear of compromising their immune system and adjusting to new relationship roles had a wide-ranging effect on patients' HRQoL. Patients acknowledged links between lung cancer and smoking but some continued to smoke. They were sensitive to the opinions of medical staff about smoking especially those who continued to smoke or recently quit. CONCLUSIONS: We conclude that staff should give clearer advice about the adverse implications of continued smoking. We discuss the potential value of diagnosis as a teachable moment for promoting smoking cessation among patients and family members.

The role of JAK/STAT signalling in the pathogenesis, prognosis and treatment of solid tumours.

Aberrant activation of intracellular signalling pathways confers malignant properties on cancer cells. Targeting intracellular signalling pathways has been a productive strategy for drug development, with several drugs acting on signalling pathways already in use and more continually being developed. The JAK/STAT signalling pathway provides an example of this paradigm in haematological malignancies, with the identification of JAK2 mutations in myeloproliferative neoplasms leading to the development of specific clinically effective JAK2 inhibitors, such as ruxolitinib. It is now clear that many solid tumours also show activation of JAK/STAT signalling. In this review, we focus on the role of JAK/STAT signalling in solid tumours, examining the molecular mechanisms that cause inappropriate pathway activation and their cellular consequences. We also discuss the degree to which activated JAK/STAT signalling contributes to oncogenesis. Studies showing the effect of activation of JAK/STAT signalling upon prognosis in several tumour types are summarised. Finally, we discuss the prospects for treating solid tumours using strategies targeting JAK/STAT signalling, including what can be learned from haematological malignancies and the extent to which results in solid tumours might be expected to differ.

Afatinib use in non-small cell lung cancer previously sensitive to epidermal growth factor receptor inhibitors: the United Kingdom Named Patient Programme.

INTRODUCTION: Afatinib prolongs progression-free survival (PFS) in patients with non-small cell lung cancer (NSCLC) who were previously sensitive to erlotinib or gefitinib. This study investigated experience of afatinib under a Named Patient Use (NPU) programme. PATIENTS AND METHODS: Retrospective data for 63 patients were collected, including demographics, dose, toxicity and clinical efficacy. RESULTS: Response rate and median PFS were 14.3% and 2.6months, respectively. Diarrhoea and rash were the most common toxicities; 46% of patients required a dose reduction and 41% had a dose delay. CONCLUSIONS: Efficacy and safety in the NPU programme are consistent with the LUX-Lung 1 trial.

DOC-MEK: a double-blind randomized phase II trial of docetaxel with or without selumetinib in wild-type BRAF advanced melanoma.

BACKGROUND: Treatment options for wild-type BRAF melanoma patients remain limited. Selumetinib, a MEK 1/2 inhibitor, suppresses pERK levels independent of BRAF and NRAS mutation status, and combination with docetaxel has demonstrated synergy in xenograft models. The aim of this study was to assess the efficacy and safety of selumetinib plus docetaxel as first-line treatment in patients with wild-type BRAF advanced melanoma. PATIENTS AND METHODS: In this double-blind multicentre phase II trial patients with wild-type BRAF melanoma were randomized (1:1) to docetaxel with selumetinib or placebo. Docetaxel 75 mg/m(2) was administered intravenously every 3 weeks up to six cycles. Selumetinib 75 mg or placebo was given orally twice daily until disease progression or unacceptable toxicity. The primary end point was progression-free survival (PFS). Tumour NRAS mutation status was analysed retrospectively and correlated with treatment outcomes. RESULTS: Eighty-three patients were randomized to docetaxel plus selumetinib (n = 41) or docetaxel plus placebo (n = 42). The PFS hazard ratio (HR) (selumetinib:placebo) was 0.75 [90% confidence interval (CI) 0.50-1.14; P = 0.130], with a median PFS of 4.23 months (90% CI 3.63-6.90) for docetaxel plus selumetinib and 3.93 months (90% CI 2.07-4.16) for docetaxel alone. There was no significant difference in overall survival. The objective response rate was 32% with selumetinib versus 14% with placebo (P = 0.059). In a retrospective subset analysis, NRAS mutation status did not affect significantly upon clinical outcomes in either arm. The combination of docetaxel and selumetinib could be administered effectively to patients with metastatic melanoma, although the combination was less well tolerated than docetaxel alone. CONCLUSIONS: The combination of docetaxel with selumetinib showed no significant improvement in PFS compared with docetaxel alone, although more patients showed a response to combination therapy. We found no evidence to support using tumour NRAS mutation as a basis for selecting patients for combined MEK inhibitor and chemotherapy. CLINICAL TRIAL: DOC-MEK (EudraCT no: 2009-018153-23).

Phase I pharmacokinetic and pharmacodynamic study of the bioreductive drug RH1.

BACKGROUND: This trial describes a first-in-man evaluation of RH1, a novel bioreductive drug activated by DT-diaphorase (DTD), an enzyme overexpressed in many tumours. PATIENTS AND METHODS: A dose-escalation phase I trial of RH1 was carried out. The primary objective was to establish the maximum tolerated dose (MTD) of RH1. Secondary objectives were assessment of toxicity, pharmacokinetic determination of RH1 and pharmacodynamic assessment of drug effect through measurement of DNA cross linking in peripheral blood mononuclear cells (PBMCs) and tumour, DTD activity in tumour and NAD(P)H:quinone oxidoreductase 1 (NQO1) polymorphism status. RESULTS: Eighteen patients of World Health Organization performance status of zero to one with advanced refractory solid malignancies were enrolled. MTD was 1430 µg/m(2)/day with reversible bone marrow suppression being dose limiting. Plasma pharmacokinetic analysis showed RH1 is rapidly cleared from blood (t(1/2) = 12.3 min), with AUC increasing proportionately with dose. The comet-X assay demonstrated dose-related increases in DNA cross linking in PBMCs. DNA cross linking was demonstrated in tumours, even with low levels of DTD. Only one patient was homozygous for NQO1 polymorphism precluding any conclusion of its effect. CONCLUSIONS: RH1 was well tolerated with predictable and manageable toxicity. The MTD of 1430 µg/m(2)/day is the dose recommended for phase II trials. The biomarkers of DNA cross linking, DTD activity and NQO1 status have been validated and clinically developed.

The influence of sex and histology on outcomes in non-small-cell lung cancer: a pooled analysis of five randomized trials.

BACKGROUND: Some non-small-cell lung cancer (NSCLC) surgical series have indicated that the positive prognostic effect of female sex is limited to patients with adenocarcinoma. We carried out a retrospective analysis to investigate the role of sex and histology on efficacy, toxicity, and dose delivery after chemotherapy. PATIENT AND METHODS: Individual patient data were pooled from five randomized, phase III, advanced NSCLC chemotherapy trials. Primary outcomes were response rate, overall survival (OS), toxicity, and dose delivery. A secondary analysis examined survival by sex in histological subgroups. RESULTS: Of 2349 patients, 34% were women. Women had a higher response rate to chemotherapy (42% versus 40%, P = 0.01) and longer survival than men (median OS 9.6 versus 8.6 months, P = 0.002). The difference in OS remained after adjusting for age, stage, performance status, and histology (hazard ratio 0.83, 95% confidence interval 0.74-0.92, P = 0.0005). Upon further examination, longer survival in women was only seen in patients with adenocarcinoma (test for interaction P = 0.006). There were no differences in hematological toxicity or transfusions. Women experienced more grade 3-4 emesis than men (P < 0.0001) and more dose delays (P = 0.02) or dose reductions (P < 0.0001). CONCLUSION: The positive prognostic effect among women is confirmed in patients receiving platinum-based chemotherapy but appears confined to those with adenocarcinoma histology.

Safety, tolerability, pharmacokinetics and pharmacodynamics of the oral cyclin-dependent kinase inhibitor AZD5438 when administered at intermittent and continuous dosing schedules in patients with advanced solid tumours.

BACKGROUND: AZD5438 is an orally bioavailable inhibitor of cyclin E-cdk2, cyclin A-cdk2 and cyclin B-cdk1 complexes. Three phase I studies assessed the clinical safety, tolerability, pharmacokinetics and pharmacodynamics of AZD5438 when administered in different dosing schedules. PATIENTS AND METHODS: AZD5438 was administered four times daily, once every 7 days (study 1), for 14 consecutive days followed by 7 days of rest (study 2), or continuously (study 3), to patients with advanced solid tumours. Dose escalation proceeded until the emergence of dose-limiting toxic effects. RESULTS: Sixty-four patients were included across the three studies (19, 17 and 28, respectively). Nausea and vomiting were the most common adverse events. When dosed continuously, 40 mg four times daily was considered intolerable, and due to safety issues, all studies were terminated prematurely. Consequently, no intolerable dose was identified during the weekly schedule. Pharmacokinetics demonstrated dose-proportional exposure, high interpatient variability and accumulation after multiple doses. Skin biopsies indicated reduced retinoblastoma protein phosphorylation at cdk2 phospho-sites; other pharmacodynamic assessments did not reveal consistent trends. CONCLUSIONS: AZD5438 was generally well tolerated in a weekly dosing schedule, but not in continuous schedules. The clinical development programme for AZD5438 was discontinued owing to tolerability and exposure data from these studies.

Validation of the comet-X assay as a pharmacodynamic assay for measuring DNA cross-linking produced by the novel anticancer agent RH1 during a phase I clinical trial.

PURPOSE: RH1 is a novel anticancer agent with potent DNA-cross linking activity. RH1 has the potential to be activated within tumors over expressing NQO1, giving maximal antitumour activity with reduced toxicity in normal tissues. RH1 has recently completed a Cancer Research UK sponsored phase I clinical trial at two different centers in the United Kingdom. The comet-X assay was a secondary endpoint in this trial and assay validation was necessary. We describe here this validation process. Whilst it is impossible to cover all variations/conditions of a pharmacodynamic assay, we have strived to evaluate and demonstrate that this assay conforms to the three R's of validation, that is robustness, reliability and reproducibility. METHODS: K562 and peripheral blood mononuclear cells were treated with either radiation alone, or with a combination of radiation and drug. These samples were then embedded in low melting point agarose and subjected to a modified version of the alkaline single cell gel electrophoresis (Comet) assay, described here as the comet-X assay. Variations in the preparation, electrophoresis, storage and scoring of these samples was investigated. In addition radiation and drug dose response curves were constructed. Finally stability of QC standards was investigated over a 30-month period. RESULTS: We have demonstrated a linear radiation-dose response in cells up to 20 Gy and drug induced DNA cross-linking up to 50 nM. From the radiation dose response curves we were able to show that the relative inaccuracy measured against a global mean value was less than 25% and the relative (within day) imprecision was less than 30% over all doses. Between day runs produced an intra assay imprecision of 21.2%. Variables involved in the electrophoresis process showed the voltage across all slides in the tank ranged from 3.1 to -2.0 (mV) whilst the current ranged from 0.8-5.5 mA. QC standards were prepared from PBMCs of healthy donors and frozen at -80 degrees C. The stability of these frozen QC standards was measured over a 30-month period. No significant deterioration in any of the control, irradiated or drug treated samples was observed. CONCLUSIONS: The comet-X assay has been shown to be a robust, reliable and reproducible assay. It is ideally suited for the evaluation of the pharmacodynamic effects of DNA cross-linking agents undergoing early clinical trials. Furthermore, this assay may provide valuable data, in conjunction with pharmacokinetics, when measuring toxicity and efficacy as part of the RH1 phase I clinical trial.

IAPs as a target for anticancer therapy.

The avoidance of apoptosis is one of the hallmarks of cancer cells. In addition, failure to induce apoptosis by anticancer agents, either due to limitations of the drug or the tumour cell evading apoptosis, is a reason for chemotherapeutic failure. Two general pathways for apoptotic cell death have been characterised, the extrinsic and intrinsic pathways which merge in the final common pathway. X-linked inhibitor of apoptosis protein (XIAP) is an anti-apoptotic protein in the final common pathway that inhibits caspases and suppresses apoptosis. XIAP is over-expressed in many cancer cell lines and cancer tissues. High XIAP expression has been correlated with resistance to chemotherapy and radiotherapy and to poor clinical outcome by some investigators. Manipulation of apoptosis is an attractive therapeutic concept. Much effort has been spent on inhibiting the anti-apoptotic protein, B cell lymphoma gene 2 (Bcl-2) which is part of the intrinsic pathway. Now attention is turning to inhibition of XIAP as a cancer drug target. It has been argued that it is more effective to block the final common pathway rather than just the intrinsic arm. Inhibition of XIAP can be with either antisense oligonucleotides (ASO) or small molecule inhibitors. In vitro, XIAP antagonists produce XIAP knockdown and apoptosis which is associated with sensitisation of tumour cells to radiotherapy and cytotoxic drugs. In vivo, XIAP antagonists have antitumour effects and sensitise tumours to the effects of chemotherapy. This review will summarise the preclinical data for both ASO and small molecule inhibition of XIAP and discuss emerging Phase I data. Future strategies for manipulation of XIAP and the clinical development of XIAP inhibitors will be discussed.

A phase II trial with RFS2000 (rubitecan) in patients with advanced non-small cell lung cancer.

Rubitecan (RFS2000, 9 nitrocamptothecin,) is a new oral topoisomerase I inhibitor. We report a phase II, single-arm, open-label study of RFS2000 as first line treatment for non-small cell lung cancer (NSCLC). Seventeen treatment-naïve patients with stage IIIB (9/17) and IV (8/17) NSCLC (11 male and 6 female) were treated, the median age was 62 years (range 52-86), and the majority of patients (14/17) were of performance status 1. RFS2000 was given orally, daily for 5 days, repeated every week. The starting dose was 1.5 mg/m(2)/day, and dose adjustment was permitted based upon toxicity. Fifteen patients had a dose escalation to 1.75 mg/m(2)/day and 7 had a second dose escalation to the protocol maximum level of 2.0 mg/m(2)/day. RFS2000 was tolerated well. Almost all adverse events were grade 1 and 2. The most frequently encountered adverse events were diarrhoea, nausea, anorexia, and lethargy. Neutropenia and thrombocytopenia were not observed in any patient. There were no responders to RFS2000 treatment, 10 patients had stable disease as their best response, whilst five had tumour progression. Two patients were not assessable for tumour response. The median survival time was 257 days (95% CI = 222-352). RFS2000 appears to be inactive at dose levels of 1.5-2.0 mg/m(2)/day in advanced NSCLC patients. Since only mild toxicity and no myelosuppression were encountered, these dose level are too low for this treatment-naïve patient population with NSCLC. Further studies at an increased dose would be required to identify whether this agent has merit in the treatment of NSCLC.

Efficacy of gemcitabine plus platinum chemotherapy compared with other platinum containing regimens in advanced non-small-cell lung cancer: a meta-analysis of survival outcomes.

PURPOSE: Gemcitabine-platinum combination activity has been clearly established in a number of phase II studies. It has also been compared against other combinations in many phase III trials. It is generally believed that all such regimens have an equivalent impact on survival. This meta-analysis aims to quantify the treatment effect of gemcitabine plus a platinum agent in the treatment of advanced NSCLC and compare the combination to other regimens used globally. DESIGN: Data from a total of 4556 patients from 13 randomized trials investigating gemcitabine in combination with a platinum agent versus any other platinum-containing regimen were included in a meta-analysis of time-to-event outcomes. RESULTS: A significant reduction in overall mortality in favor of gemcitabine-platinum regimens was observed, hazard ratio (HR) 0.90 (95% CI: 0.84-0.96) with an absolute benefit at 1 year of 3.9%. Median survival was 9.0 months for the gemcitabine-platinum regimens and 8.2 months for the comparator regimens. Sub-group analysis of the first- and second-generation platinum-based comparator regimens also indicated a significant benefit for gemcitabine-platinum regimens, HR 0.84 (CI: 0.71-0.9985). Analysis of third-generation agent plus platinum regimens showed a non-significant trend favoring gemcitabine-platinum regimens, HR 0.93 (CI: 0.86-1.01). There was a significant decrease in the risk of disease progression in favor of gemcitabine-platinum regimens, HR 0.88 (CI: 0.82-0.93). An absolute benefit of 4.2% at 1 year was estimated. Median progression-free survival was 5.1 months for gemcitabine-platinum regimens compared with 4.4 months for the comparator regimens. Sub-group analysis indicated a statistically significant progression-free survival benefit for patients assigned to gemcitabine-platinum treatment compared to first- and second-generation platinum regimens, HR 0.85 (CI: 0.77-0.94), and third-generation agent plus platinum regimens, HR 0.89 (CI: 0.82-0.96).

Incidence of cerebral metastases in patients treated with trastuzumab for metastatic breast cancer.

Trastuzumab is an effective treatment for patients with metastatic breast cancer (MBC) that overexpresses HER-2. A high incidence of brain metastases (BM) has been noted in patients receiving trastuzumab. A retrospective chart review was conducted of 100 patients commencing trastuzumab for metastatic breast cancer from July 1999 to December 2002, at the Christie Hospital. Seven patients were excluded; five patients developed central nervous system metastases prior to starting trastuzumab, and inadequate data were available for two. Out of the remaining 93 patients, 23 (25%) have developed BM to date. In all, 46 patients have died, and of these 18 (39%) have been diagnosed with BM prior to death. Of the 23 patients developing BM, 18 (78%) were hormone receptor negative and 18 (78%) had visceral disease. Univariate analysis showed a significant association between the development of cerebral disease and both hormone receptor status and the presence of visceral disease. In conclusion, a high proportion of patients with MBC treated with trastuzumab develop symptomatic cerebral metastases. HER-2-positive breast cancer may have a predilection for the brain, or trastuzumab therapy may change the disease pattern by prolonging survival. New strategies to address this problem require investigation in this group of patients.

DT-diaphorase: a target for new anticancer drugs.

DT-diaphorase (DTD) is an obligate two-electron reductase which bioactivates chemotherapeutic quinones. DTD levels are elevated in a number of tumour types, including non-small cell lung carcinoma, colorectal carcinoma, liver cancers and breast carcinomas, when compared to the surrounding normal tissue. The differential in DTD between tumour and normal tissue should allow targeted activation of chemotherapeutic quinones in the tumour whilst minimising normal tissue toxicity. The prototypical bioreductive drug is Mitomycin C (MMC) which is widely used in clinical practice. However, MMC is actually a relatively poor substrate for DTD and its metabolism is pH-dependent. Other bioreductive drugs have failed because of poor solubility and inability to surpass other agents in use. RH1, a novel diaziridinylbenzoquinone, is a more efficient substrate for DTD. It has been demonstrated to have anti-tumour effects both in vitro and in vivo and demonstrates a relationship between DTD expression levels and drug response. RH1 has recently entered a phase I clinical trial in solid tumours under the auspices of Cancer Research UK. Recent work has demonstrated that DTD is present in the nucleus and is associated with both p53 and the heat shock protein, HSP-70. Furthermore, DTD is inducible by several non-toxic compounds and therefore much interest has focussed on increasing the differential in DTD levels between tumour and normal tissues.