Evaluation of a quality improvement intervention to reduce anastomotic leak following right colectomy (EAGLE): pragmatic, batched stepped-wedge, cluster-randomized trial in 64 countries

BACKGROUND

Anastomotic leak affects 8 per cent of patients after right colectomy with a 10-fold increased risk of postoperative death. The EAGLE study aimed to develop and test whether an international, standardized quality improvement intervention could reduce anastomotic leaks.

METHODS

The internationally intended protocol, iteratively co-developed by a multistage Delphi process, comprised an online educational module introducing risk stratification, an intraoperative checklist, and harmonized surgical techniques. Clusters (hospital teams) were randomized to one of three arms with varied sequences of intervention/data collection by a derived stepped-wedge batch design (at least 18 hospital teams per batch). Patients were blinded to the study allocation. Low- and middle-income country enrolment was encouraged. The primary outcome (assessed by intention to treat) was anastomotic leak rate, and subgroup analyses by module completion (at least 80 per cent of surgeons, high engagement; less than 50 per cent, low engagement) were preplanned.

RESULTS

A total 355 hospital teams registered, with 332 from 64 countries (39.2 per cent low and middle income) included in the final analysis. The online modules were completed by half of the surgeons (2143 of 4411). The primary analysis included 3039 of the 3268 patients recruited (206 patients had no anastomosis and 23 were lost to follow-up), with anastomotic leaks arising before and after the intervention in 10.1 and 9.6 per cent respectively (adjusted OR 0.87, 95 per cent c.i. 0.59 to 1.30; P = 0.498). The proportion of surgeons completing the educational modules was an influence: the leak rate decreased from 12.2 per cent (61 of 500) before intervention to 5.1 per cent (24 of 473) after intervention in high-engagement centres (adjusted OR 0.36, 0.20 to 0.64; P < 0.001), but this was not observed in low-engagement hospitals (8.3 per cent (59 of 714) and 13.8 per cent (61 of 443) respectively; adjusted OR 2.09, 1.31 to 3.31).

CONCLUSION

Completion of globally available digital training by engaged teams can alter anastomotic leak rates. Registration number: NCT04270721 (http://www.clinicaltrials.gov).

The accuracy of MRI in detecting pathological complete response following neoadjuvant chemotherapy in different breast cancer subtypes

BACKGROUND

Pathological complete response (pCR) following neo-adjuvant chemotherapy (NACT) for breast cancer is associated with improved disease-free and overall survival in certain breast cancer subtypes. Magnetic Resonance Imaging (MRI) is increasingly used as standard to assess treatment response in patients receiving NACT. The aim of this study was to determine the clinical utility of MRI in accurately predicting pCR post-NACT.

METHODS

A single-centre, retrospective study was conducted in breast cancer patients, who received NACT between 2013 and 2020. Patients who had an MRI before and after NACT were included. Pathological and MRI radiological response rates to NACT were analyzed and MRI accuracy assessed in detecting pCR according to breast cancer subtype.

RESULTS

One hundred and sixty-seven patients were included in the study. Forty-one of the 167 patients achieved pCR (24.6 %), with the highest proportion in HR- HER2+ subgroup (58.3 %), followed by triple negative breast cancer (TNBC) (35 %). Only 22.2 % and 10.5 % of patients with HR + HER2+ and HR + HER2-respectively achieved pCR. The overall accuracy of MRI in predicting pCR after NACT was 77.3 %. The greatest accuracy was in TNBC (87.5 %) with a specificity and positive predictive value (PPV) of 100 % and the highest number of correctly diagnosed complete responses (14 of 40). MRI was less accurate in predicting response rates in HR + HER2- (PPV 91.2 %) and HR + HER2+ groups (PPV 90.5 %). MRI performed significantly better in predicting complete response in TNBC compared to HR + HER2-subtype (p = 0.0057).

CONCLUSION

MRI is a clinically useful adjunct in assessing pCR following NACT and appears to predict pathological response more accurately in TNBC compared to HR + HER2-breast cancer subtypes. This has significant clinical implications in terms of surgical planning, adjuvant treatment options and prognosis.

The protective role of phosphodiesterase inhibitors in preventing colorectal cancer and advanced colorectal polyps: a systematic review and meta-analysis

AIM

Inflammatory cells within the tumour microenvironment are the driving forces behind colorectal cancer (CRC) tumourigenesis. Understanding the different pathways involved in CRC carcinogenesis paves the way for effective repurposing of drugs for cancer prevention. Emerging data from preclinical and clinical studies suggest that, due to their antiproliferative and anti-inflammatory properties, phosphodiesterase-5 inhibitors (PDE5i) might have an anticancer effect. The aim of this study was to clarify through systematic review and meta-analysis of published peer-reviewed studies whether an association exists between PDE5i use and CRC risk.

METHOD

This study was guided by the Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines. Prospective registration was performed on PROSPERO (CRD42022372925). A systematic review was performed for studies reporting CRC and advanced colorectal polyp incidence in PDE5i 'ever-users' and PDE5i 'never-users'. Meta-analysis was performed using RevMan version 5.

RESULTS

Four observational cohort studies and two case-control studies, comprising 995 242 patients were included in the final analysis, of whom 347 126 were PDE5i ever-users. Patients who were PDE5i ever-users had a significantly lower incidence of CRC or advanced colorectal polyps than never-users (OR 0.88, CI 0.79-0.98, p = 0.02). To examine the primary preventative role of PDE5i, subgroup analysis of four studies including patients without a previous history of CRC found that use of PDE5i was associated with a lower incidence of CRC (OR 0.85, CI 0.75-0.95, p = 0.005, I2  = 64%). There was no significant temporal relationship found between PDE5i use and CRC risk as both current users and previous users had a significantly lower incidence of CRC than never-users.

CONCLUSION

Our study found a significant anticancer effect of PDE5i, as shown by a reduced risk of CRC in the context of both primary and secondary CRC prevention.

Effect of obesity on perioperative outcomes following gastrointestinal surgery: meta-analysis

BACKGROUND

Obesity can pose perioperative challenges related to obesity-associated co-morbidities and technical factors. However, the true impact of obesity on postoperative outcomes is not well established and reports are conflicting. The aim was to perform a systematic review and meta-analysis to explore the effect of obesity on perioperative outcomes for general surgery procedures in distinct obesity subtypes.

METHODS

A systematic review was performed for studies reporting postoperative outcomes in relation to BMI in upper gastrointestinal, hepatobiliary and colorectal based on an electronic search using the Cochrane Library, Science Direct, PubMed and Embase up to January 2022. The primary outcome was the incidence of 30-day postoperative mortality among patients with obesity undergoing general surgical procedures in comparison to patients with normal range BMI.

RESULTS

Sixty-two studies, including 1 886 326 patients, were eligible for inclusion. Overall, patients with obesity (including class I/II/II) had lower 30-day mortality rates in comparison to patients with a normal BMI (odds ratio (OR) 0.75, 95 per cent c.i. 0.66 to 0.86, P < 0.0001, I2 = 71 per cent); this was also observed specifically in emergency general surgery (OR 0.83, 95 per cent c.i. 0.79 to 0.87, P < 0.0000001, I2 = 7 per cent). Compared with normal BMI, obesity was positively associated with an increased risk of 30-day postoperative morbidity (OR 1.11, 95 per cent c.i. 1.04 to 1.19, P = 0.002, I2 = 85 per cent). However, there was no significant difference in postoperative morbidity rates between the cohorts of patients with a normal BMI and class I/II obesity (OR 0.98, 95 per cent c.i. 0.92 to 1.04, P = 0.542, I2 = 92 per cent). Overall, the cohort with obesity had a higher rate of postoperative wound infections compared with the non-obese group (OR 1.40, 95 per cent c.i. 1.24 to 1.59, P < 0.0001, I2 = 82 per cent).

CONCLUSION

These data suggest a possible 'obesity paradox' and challenge the assumption that patients with obesity have higher postoperative mortality compared with patients with normal range BMI. Increased BMI alone is not associated with increased perioperative mortality in general surgery, highlighting the importance of more accurate body composition assessment, such as computed tomography anthropometrics, to support perioperative risk stratification and decision-making.

REGISTRATION NUMBER

CRD42022337442 (PROSPERO https://www.crd.york.ac.uk/prospero/).

Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

BACKGROUND

Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres.

METHODS

This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low-middle-income countries.

RESULTS

In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of 'single-use' consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low-middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia.

CONCLUSION

This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high- and low-middle-income countries.

Readability and Quality of Online Health Information Regarding Parathyroidectomy

Objective

Assessment of the readability and quality of online health information regarding parathyroidectomy.

Study Design

Cross-sectional analysis.

Setting

Websites providing patient-oriented health information regarding parathyroidectomy obtained via the Google search engine.

Methods

The top 75 Google search results for “parathyroidectomy,”“parathyroid surgery,” and “parathyroid gland removal” were reviewed. Websites were categorized by website type and country of origin. Readability was assessed by Flesch-Kincaid Grade Level and Simple Measure of Gobbledygook. Website quality was assessed per JAMA benchmark criteria and the DISCERN instrument.

Results

A total of 74 unique websites were evaluated. The mean readability of the assessed websites exceeded the recommended sixth-grade reading level on the Flesch-Kincaid Grade Level and Simple Measure of Gobbledygook (P < .001). Readability did not vary significantly by website type. Websites originating from the United Kingdom were significantly more readable than those from the United States. The majority of assessed websites were of poor quality (n = 42, 56.8%) on assessment based on the DISCERN instrument. Quality varied significantly by website category on the JAMA benchmark criteria (P < .001) and DISCERN score (P = .049) with commercial websites receiving the highest scores. DISCERN score also varied significantly by country of origin (P = .036) with UK sites receiving highest mean DISCERN scores.

Conclusion

Online health information regarding parathyroidectomy is largely of poor quality and is poorly readable for many patients. Institutions utilizing well-defined guidelines for development of patient educational resources may provide online health information of greater quality and readability.

Increasing the use of perioperative risk scoring in emergency laparotomy: nationwide quality improvement programme

Background

Emergency laparotomy is associated with high morbidity and mortality. The early identification of high-risk patients allows for timely perioperative care and appropriate resource allocation. The aim of this study was to develop a nationwide surgical trainee-led quality improvement (QI) programme to increase the use of perioperative risk scoring in emergency laparotomy.

Methods

The programme was structured using the active implementation framework in 15 state-funded Irish hospitals to guide the staged implementation of perioperative risk scoring. The primary outcome was a recorded preoperative risk score for patients undergoing an emergency laparotomy at each site.

Results

The rate of patients undergoing emergency laparotomy receiving a perioperative risk score increased from 0–11 per cent during the exploratory phase to 35–100 per cent during the full implementation phase. Crucial factors for implementing changes included an experienced central team providing implementation support, collaborator engagement, and effective communication and social relationships.

Conclusions

A trainee-led QI programme increased the use of perioperative risk assessment in patients undergoing emergency laparotomy, with the potential to improve patient outcomes and care delivery.

The positive predictive value of vacuum assisted biopsy (VAB) in predicting final histological diagnosis for breast lesions of uncertain malignancy (B3 lesions): A systematic review & meta-analysis

INTRODUCTION

High-risk or B3 breast lesions are considered lesions of uncertain malignant potential and comprise between 5 and 12% of initial biopsy results. We sought to perform a systematic review and meta-analysis of studies published within the last twenty years to determine the pooled Positive Predictive Value (PPV) of VAB in selected B3 lesions.

METHODS

The study report is based on the guidelines of PRISMA and Meta-Analysis of Observational Studies in Epidemiology.

OUTCOMES

The primary outcome of this study was to determine the PPV of VAB in determining final histological diagnosis in B3 breast lesions using pooled estimates. The secondary outcomes were to determine if needle gauge or the re-classification of Lobular Carcinoma in Situ(LCIS) introduced in 2012 influenced pooled estimates.

RESULTS

78 studies incorporating 6,377 B3 lesions were included in this review, 1214 of which were upgraded to DCIS or invasive malignancy following surgical excision(19%). The pooled PPV of VAB in Atypical Ductal Hyperplasia(ADH) and Lobular Neoplasia(LN) were 0.79(CI 0.76-0.83) and 0.84(CI 0.8-0.88). VAB of Flat Epithelial Atypia(FEA), radial scar and papillary lesions with/without atypia all had a pooled PPV >90% (underestimation rates 7%, 1%, 5% and 3% respectively). Needle gauge size and the change in LCIS classification did not appear to influence underestimation rates on subgroup analysis.

CONCLUSION

Results from this meta-analysis suggests it is reasonable to perform VAB as definitive treatment for certain B3 lesions, specifically LN, FEA, radial scar, and papillary lesions when specific criteria are fulfilled. Surgical excision should continue as the mainstay of treatment for ADH.

OUP accepted manuscript

Background

The significance of exogenous hormone manipulation as part of fertility treatment and its relationship to the development of breast cancer remains uncertain. Several historical reviews have been performed with conflicting results. This study is an updated meta-analysis to determine whether there is a causal relationship between different fertility treatments and breast cancer.

Methods

The study report is based on the guidelines of PRISMA and Meta-Analysis of Observational Studies in Epidemiology. Studies published within the last 20 years were included to reflect up to date in vitro fertilization (IVF) practice. This study was prospectively registered on PROSPERO on 07/04/2021, registration identification CRD42021247706. The primary outcome of the study was to determine whether there is an increased incidence of breast cancer in women treated with hormonal fertility treatment. The secondary outcomes were to determine whether fertility treatments were individually associated with excess breast-cancer risk.

Results

Overall, 25 studies, including 617 479 participants, were eligible for inclusion. There was no significant breast-cancer risk association with fertility treatment (compared with general and subfertility reference groups). Summary odds ratio of all included studies was 0.97 (95 per cent c.i. 0.90 to 1.04). Women who received six or more IVF cycles did not have an increased risk of breast cancer. Similarly, there was no excess breast-cancer risk associated with clomiphene, human chorionic gonadotropin, gonadotropin analogues and progesterone when examined individually. Comparably, there was no significant association between fertility treatment and excess breast-cancer risk in patients with more than 10 years’ follow-up. Summary odds ratio was 0.97 (95 per cent c.i. 0.85 to 1.12).

Conclusion

This meta-analysis did not find a significant association between fertility treatments and excess breast-cancer risk. Women considering IVF should be informed that it does not appear to increase breast-cancer risk.

1443 Comparison of Outcomes Between Immediate Direct-to-Implant Breast Reconstruction versus Two-Stage Implant Breast Reconstruction; a Systematic Review and Meta-analysis

Background

Direct-to-implant (DTI) breast reconstruction is increasingly performed as the preferred method of immediate breast reconstruction following mastectomy. The proposed advantages of DTI over two-stage tissue expander (TE)/implant reconstruction relate to fewer surgical procedures. This systematic review and meta-analysis aims to evaluate the safety and efficacy of DTI versus conventional TE/implant breast reconstruction.

Method

A systematic review was performed (PubMed, Embase, Scopus) to identify relevant studies that compared outcomes between DTI and TE/Implant reconstructions. Publications up to October 2020 were included. The primary outcome was overall complication rate. Secondary outcomes included infection rate and implant loss.

Results

Nineteen studies, including 32,971 implant-based breast reconstructions, were analysed. Median age was 48 years. Mean BMI was 25.9. There was no statistically significant difference between the two groups. Duration of follow up ranged from 1-60 months. Overall complications were significantly more likely to occur in the DTI group (OR 1.81 [1.17-2.79]). Overall complications refers to all reported complications including seroma, haematoma, would dehiscence, infection, skin necrosis and capsular contracture. Implant loss was also significantly higher in the DTI cohort (OR 1.31 [1.12-1.78]). There was no significant difference in infection rates between the two groups. Subgroup analyses, focusing on high-powered multicentre studies showed that the risks of overall complications were significantly higher in the DTI group (OR 1.51 [1.06-2.14]).

Conclusions

This meta-analysis demonstrates significantly greater risk of complications and implant loss in the DTI breast reconstruction group. These findings serve to aid both patients and clinicians in the decision-making process regarding implant reconstruction following mastectomy

The Surgical Safety Huddle: Novel Quality Improvement Patient Safety Initiative

Background: Acutely deteriorating patients are entitled to the best possible care which includes early recognition and timely appropriate intervention to reduce adverse events, unnecessary admissions to intensive care and/or cardiac arrest. Aim: To reduce the number of poor outcomes for surgical patients with a National Early Warning Score (NEWS) score ≥7 in our institution by 50%. A poor outcome was defined as: 1. Cardiac arrest 2. NEWS >7 not improving after 72 hours 3. Transfer to ICU >6 hours Methods: Surgical inpatients from a variety of surgical specialties (general, vascular, breast, colorectal, hepatobiliary, and plastic surgery) in a large university teaching hospital were included. Quality improvement tools were used to generate regular dialogue with the clinical teams, resulting in the concept of the surgical safety huddle being proposed. Deteriorating patients were highlighted at the daily huddle and a plan of early intervention was implemented. An incremental approach with continuous PDSA [Plan- Do-Study-Act] cycles and subsequent feedback was adopted on the surgical ward to develop the huddle. Poor patient outcomes were analysed prospectively via chart reviews. Results: Prior to the introduction of the “surgical huddle” 110 patients with NEWS >7 were audited. Twenty-eight of these patients had a poor outcome at 72 hours (25%). Following the introduction of the surgical huddle supported by the deteriorating patient team, 64 patients with NEWS >7 were reviewed. Three of these patients had a poor outcome at 72 hours (4.7%). The introduction of the surgical huddle increased the interval between cardiac arrests more than sixfold on the surgical ward. Discussion: The introduction of the surgical safety huddle supported by the deteriorating patient response team reduced the number of cardiac arrests and poor outcomes in a surgical inpatient cohort.

Urogenital function following robotic and laparoscopic rectal cancer surgery: meta-analysis

BACKGROUND

Mixed results are reported on clinical and cancer outcomes in laparoscopic rectal cancer surgery (LRCS) compared with robotic rectal cancer surgery (RRCS). However, more favourable functional outcomes are reported following RRCS. This study compared urinary and sexual function following RRCS and LRCS in male and female patients.

METHODS

A systematic review and meta-analysis of urinary and sexual function after RRCS and LRCS was performed following PRISMA and MOOSE guidelines, and registered prospectively with PROSPERO (ID:CRD42020164285). The functional outcome reporting tools most commonly included: the International Prostate Symptom Score (IPSS), International Index of Erectile Function (IIEF) and Female Sexual Function Index (FSFI). Mean scores and changes in mean scores from baseline were analysed using RevMan version 5.3.

RESULTS

Ten studies were included reporting on 1286 patients. Some 672 patients underwent LRCS, of whom 380 (56.5 per cent) were men and 116 (17.3 per cent) were women (gender not specified in 176 patients, 26.2 per cent). A total of 614 patients underwent RRCS, of whom 356 (58.0 per cent) were men and 83 (13.5 per cent) were women (gender not specified in 175 patients, 28.5 per cent). Regarding urinary function in men at 6 months after surgery, IPSS scores were significantly better in the RRCS group than in the LRCS group (mean difference (MD) -1.36, 95 per cent c.i. -2.31 to -0.40; P = 0.005), a trend that persisted at 12 months (MD -1.08, -1.85 to -0.30; P = 0.007). ΔIIEF scores significantly favoured RRCS at 6 months [MD -3.11 (95%CI -5.77, -0.44) P <0.021] and 12 months [MD -2.76 (95%CI -3.63, -1.88) P <0.001] post-operatively. Mixed urinary and sexual function outcomes were reported for women.

CONCLUSION

This meta-analysis identified more favourable urinary and erectile function in men who undergo robotic compared with conventional laparoscopic surgery for rectal cancer. Outcomes in women did not identify a consistently more favourable outcome in either group. As robotic rectal cancer surgery may offer more favourable functional outcomes it should be considered and discussed with patients.

Optimal timing of surgery following breast cancer neoadjuvant chemotherapy: A systematic review and meta-analysis

BACKGROUND

Administration of chemotherapy before breast surgery has the potential to reduce the risk of distant recurrence by targeting micrometastasis as well as allowing a more minimalistic approach to surgical intervention. We performed a systematic review to determine the optimum timing of surgery post breast cancer neoadjuvant chemotherapy (NACT).

METHODS

The primary outcome was to determine whether the timing of surgery post NACT impacted overall survival (OS) and disease-free survival (DFS). We compared patient outcomes between those who had surgery within 8 weeks of completion of NACT to those that had surgery after 8 weeks. An outcome comparison between <4 weeks and 4-8 weeks was also performed. Secondary outcome included complete pathological response (pCR) post NACT. A meta-analysis was performed using the Mantel-Haenszel method.

RESULTS

Five studies, including 8794 patients were eligible for inclusion. Patients that had surgery within 8 weeks of completion of NACT had a statistically significant improved OS(OR 0.47, 95% c. i 0.34-0.65) and DFS(OR 0.71 (95% c. i 0.52-0.98, P = 0.04). There were no survival advantages associated with having surgery less than 4 weeks post completion of NACT (OR 0.78, 95% c. i 0.46-1.33, P = 0.37). There was no difference in pCR rate between those that had surgery <4 weeks and 4-8 weeks (OR 1.01, 95% c. i 0.80-1.28, P = 0.93).

CONCLUSION

This meta-analysis shows that the optimum timing of surgery post completion of NACT is 4-8 weeks as it is associated with increased OS and DFS.

Association of Circulating Tumor DNA With Disease-Free Survival in Breast Cancer: A Systematic Review and Meta-analysis

IMPORTANCE

Fragmented DNA is continuously released into the circulation following apoptosis and necrosis of both cancerous and noncancerous cells; when it is released by cancer cells, it is specifically known as circulating tumor DNA (ctDNA). Previous studies have suggested that ctDNA can reflect tumor burden and guide potential therapeutic targets.

OBJECTIVE

To determine the association of ctDNA with breast cancer disease-free survival (DFS) and progression-free survival in early, locally advanced, and metastatic breast cancer.

DATA SOURCES

An electronic search was conducted using the Cochrane Library, ScienceDirect, PubMed, and Embase from July 30, 2019, to October 31, 2019; all languages were included. The following search terms were used: ctDNA OR circulating tumor DNA OR liquid biopsy AND breast cancer OR breast carcinoma OR breast tumor AND prognosis OR survival. All titles were screened, and the appropriate abstracts were reviewed. If any data were missing, the authors contacted the study authors for permission to access data and extrapolate hazard ratios (HRs).

STUDY SELECTION

To be included in the analysis, the studies had to meet the following prespecified inclusion criteria: (1) a ctDNA blood sample was measured; (2) DFS, progression-free survival, or relapse-free survival was reported as an HR; and (3) the patient population only had breast cancer. Retrospective and prospective observational cohort studies were included.

DATA EXTRACTION AND SYNTHESIS

Two authors (C.C. and C.F.) independently reviewed the literature. All data were recorded independently by both authors and were compared at the end of the reviewing process to limit selection bias. Duplicates were removed and any disparities were clarified. Data were pooled using a fixed-effects or random-effects model according to the study heterogeneity. This study adhered to the guidelines of the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) and Meta-Analysis of Observational Studies in Epidemiology (MOOSE).

MAIN OUTCOMES AND MEASURES

The primary outcome was the association of ctDNA with DFS or relapse-free survival in breast cancer. Secondary outcomes focused on subgroup analysis in the setting of early breast cancer and metastatic breast cancer.

RESULTS

From a total of 263 publications found using the predefined search terms, data from 8 studies (3.0%) reporting on 739 patients in total were suitable for inclusion. Circulating tumor DNA gene variation detection (both before and after treatment) was statistically significantly associated with shorter DFS (HR, 4.44; 95% CI, 2.29-8.61; P < .001). Detection of ctDNA was statistically significantly associated with a reduction in DFS in both the early breast cancer subgroup (HR, 8.32; 95% CI, 3.01-22.99; P < .001) and the metastatic or locally advanced subgroup (HR, 1.91; 95% CI, 1.35-2.71; P < .001). Pretreatment and posttreatment plasma sample collection was analyzed in both early and metastatic groups. The posttreatment group encompassed both surgical and oncologic therapy. Pretreatment plasma detection of ctDNA was statistically significantly associated with reduced DFS (HR, 3.30; 95% CI, 1.98-5.52; P < .001). Posttreatment sampling of ctDNA failed to achieve statistical significance (HR, 8.17; 95% CI, 1.01-65.89; P = .05).

CONCLUSIONS AND RELEVANCE

In this systematic review and meta-analysis, elevated plasma ctDNA was associated with a high risk of relapse. This finding suggests that plasma ctDNA may provide an excellent method to stratify risk and personalize patient follow-up.

Can the Neutrophil to Lymphocyte Ratio Predict Complete Pathologic Response to Neoadjuvant Breast Cancer Treatment? A Systematic Review and Meta-analysis

The systemic inflammatory response plays a role in tumor progression and development. The neutrophil to lymphocyte ratio (NLR) is a biochemical marker of systemic inflammation and is increasingly gaining appreciation for its prognostic role in predicting breast cancer outcomes. Previous research has demonstrated that patients who achieve a complete pathologic response (pCR) to neoadjuvant breast cancer treatment have a more favorable disease-free survival. This study aimed to assess whether the NLR can predict pCR to neoadjuvant therapy in breast cancer. A meta-analysis of 8 relevant studies was performed. The primary endpoint included pCR. Secondary endpoint included 5-year disease-free survival. Eight studies were included, reporting on 1586 patients. A total of 363 (22.88%) patients achieved pCR post neoadjuvant therapy. A lower NLR was associated with a greater rate of pCR (odds ratio, 1.83; 95% confidence interval, 1.15-2.91; P = .0003). Only 4 studies produced data on disease-free survival. A lower NLR was associated with a higher 5-year disease-free survival; however, this did not achieve statistical significance (hazard ratio, 1.38; 95% confidence interval, 0.82-2.31; P = .02). Sub-group analysis of sample size, NLR value, and geographic location proved statistically significant in determining an association between NLR and pCR. This meta-analysis found NLR to be a predictor for pCR in patients with breast cancer. All of the studies reviewed were retrospective cohort studies. Adequately sized, prospective clinical trials are needed to understand if NLR could become an important prognostic indicator of pCR.

Deadly combination: Clostridium septicum and colorectal malignancy

Gas gangrene is a life-threatening, necrotising soft tissue infection. Colorectal malignancy-associated Clostridiumsepticum is a rare cause of gas gangrene. This case outlines an initial presentation of colonic malignancy as gas gangrene from C.septicum infection.A 69-year-old man presented with abdominal pain, vomiting and constipation. Abdominal X-ray revealed dilated small bowel loops. Lactate was elevated. A diagnosis of small bowel obstruction was made. Subsequent CT revealed caecal thickening and subcutaneous emphysema overlying the left flank. Clinically, he became haemodynamically unstable. Examination revealed crepitus overlying the left flank in keeping with gas gangrene. The patient required immediate surgical debridement. Tissue specimens cultured C.septicum Following a complicated postoperative period, he was transferred to the plastic surgery team for further tissue debridement and reconstruction. A colonoscopy was later performed which was suspicious for malignancy. Colorectal multidisciplinary team discussion is awaited.

Emergency splenectomy postelective colonoscopy

Colonoscopy is the gold standard for investigation of colorectal carcinoma and inflammatory bowel disease. Splenic injury is a rare but potentially fatal complication of colonoscopy. The present case study outlines the early clinical presentation and rapid deterioration of a patient with a splenic injury after an elective colonoscopy. A 70-year-old female underwent a colonoscopy for investigation of altered bowel habit. The procedure was documented as difficult due to the presence of 'stiff loopy colon'. In recovery, patient's condition deteriorated and she was moved to the ward for further assessment. She gradually became haemodynamically unstable and displayed signs of peritoneal irritation. Initial attempts of fluid resuscitation failed to improve patient's clinical condition. Further testing revealed a significant drop in haemoglobin and CT confirmed the diagnosis of a splenic rupture. She underwent an emergency splenectomy that evening. Postoperatively she was managed in the high dependency unit.

Twenty four-hour helpline access to expert management advice for food-allergy-triggered anaphylaxis in infants, children and young people: a pragmatic, randomized controlled trial

BACKGROUND

Anaphylaxis is a life-threatening emergency. If promptly administered, adrenaline is potentially life-saving. Many food-allergic-children/carers are unsure when to use their adrenaline autoinjectors, contributing to a low quality of life and worse outcomes in the setting of an acute allergic reaction.

OBJECTIVES

The aim of this study was to assess the effectiveness of 24-hour telephone access to specialist clinical advice on disease-specific quality of life.

METHODS

A pragmatic two-arm, parallel-group randomized control trial was conducted. Children/carers (<16 years) with food allergy, trained in adrenaline auto-injector use, were recruited from a hospital-based paediatric allergy clinic. Baseline disease-specific quality of life was ascertained using the validated Food-Allergy-Related Quality-of-Life Questionnaire (FAQLQ), either Parent Form, Child Form or Teenager Form depending on child's age. Participants were then centrally randomized for a 6-month period to 24-hour telephone specialist support line or to usual care. The primary outcome measure was a change in FAQL scores, at one and 6 months postrandomization, compared with baseline. The minimum clinically important difference (MCID) in score is 0.5.

RESULTS

Fifty two children/carers were recruited. FAQL scores remained static in the control group across the three time points. Scores gradually improved in the intervention group, with a significant difference seen at 6 months (T1-T3 Mean difference = -1.5, (CI 0.87-2.25) P < 0.005] Follow-up questionnaires, 6 months after the intervention was removed, T4, showed sustained significant difference between the groups (control M = 3.0; intervention M = 1.1[t = -4.113, P < 0.05]).

CONCLUSION

The 24-hour helpline improved food-allergy-specific quality of life in children. Six-month intervention support resulted in sustained benefits for at least a further 6 months.

Longitudinal validity and responsiveness of the Food Allergy Quality of Life Questionnaire - Parent Form in children 0-12 years following positive and negative food challenges

BACKGROUND

There are no published studies of longitudinal health-related quality of life (HRQL) assessments of food-allergic children using a disease-specific measure.

OBJECTIVE

This study assessed the longitudinal measurement properties of the Food Allergy Quality of Life Questionnaire - Parent Form (FAQLQ-PF) in a sample of children undergoing food challenge.

METHODS

Parents of children 0-12 years completed the FAQLQ-PF and the Food Allergy Independent Measure (FAIM) pre-challenge and at 2 and 6 months post food challenge. In order to evaluate longitudinal validity, differences between Group A (positive challenge) and Group B (negative challenge) were expected over time. We computed correlation coefficients between change scores in the FAQLQ-PF and change scores in the FAIM. To determine the minimally important difference (MID), we used distributional criterion and effect size approaches. A logistic regression model profiled those children falling below this point.

RESULTS

Eighty-two children underwent a challenge (42 positive; 40 negative). Domains and total score improved significantly at pos-challenge time-points for both groups (all P<0.05). Sensitivity was demonstrated by significant differences between positive and negative groups at 6 months [F(2, 59)=6.221, P<0.003] and by differing improvement on relevant subscales (P<0.05). MID was 0.45 on a seven-point response scale. Poorer quality of life at baseline increased the odds by over 2.0 of no improvement in HRQL scores 6-month time-point. General maternal health (OR 1.252), number of foods avoided (OR 1.369) and children >9 years (OR 1.173) were also predictors. The model correctly identified 84% of cases below MID.

CONCLUSION

The FAQLQ-PF is sensitive to change, and has excellent longitudinal reliability and validity in a food-allergic patient population. The standard error of measurement value of 0.5 points as a threshold for meaningful change in HRQL questionnaires was confirmed. The FAQLQ-PF may be used to identify problems in children, to assess the effectiveness of clinical trials or interventions, and to guide the development of regulatory policies.

The utility of a specific hepatic CYP-3A4 probe (C14-Erythromycin breath test [EBT]) versus the general CYP-P450 probe (antipyrine clearance [ACL] test), for the prediction of docetaxel (D) pharmacokinetics (PK)

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Background: BSA-based cytotoxic dosing does not account for the individual variability in drug disposition. In the case of D, CYP 3A4 probes such as the EBT have been assessed to individualise dosing, but inconsistently. This report is the first study comparing the EBT directly with the widely available general P450 probe, the ACL test, for the prediction of D PK when given either q 21 days or weekly. Methods: Patients (pts) with pre-treated advanced malignancy suitable for D therapy, Se bilirubin≤1.0xUNL, AST≤1.5xUNL & ALP≤2.5xUNL, were entered. Prior to D therapy, pts underwent EBT and ACL test. Pts were given IV 14C N-methyl-erythromycin and exhaled breath samples were captured for 14CO2 from 5–120 mins post. The EBT parameters determined: 14CO2 flux at 10 min (CO2f10), & 20 min (CO2f20), (iii) terminal rate constant kCO2 (iv) AUCCO2,(0-∞) & AUCCO2,(0–60). For the ACL test, pts was given oral antipyrine 10mg/kg, blood samples were collected from 0, 4 & 24 hrs post, and serum levels measured: ACL was calculated as per Farrell et al.(Br J Clin Pharmacol 18:559). D was given 75mg/m2 q21 days or 35mg/m2 weekly. Samples taken for D PK in course 1 day 1, parameters included: half life (tD1/2), & clearance (CLD). Correlations were sought between EBT parameters, ACL values and D PK parameters. Results: 20 pts accrued, M:F= 12:8, Median age= 65. Mean BSA = 1.77m2 (1.44–2.07). D q21 days:D weekly= 13:7. EBT parameters (N= 19) (Mean, [CV%]): CO2f10 (%/min) 0.051 (106), CO2f20 0.052 (82), kCO2 (min- 1) 0.007 (22), AUCCO2,(0-∞) 7.9 (85), AUCCO2,(0–60) 2.64 (81). ACL (N=19) (ml/min); 35.8 (37). No significant differences observed for EBT parameters and ACL between the q21 days vs weekly dosing. D PK parameters (N=19): CLD (l/hr) 57.2 (36), tD1/2 (hrs) 12.7 (33). No correlations were observed between the D PK and EMBT parameters for all pts and regardless of the regimen given. For D weekly pts, a significant linear relationship was observed between CLD and ACL (P =0.007, R2= 79.47%). Conclusions: The utility of EBT for the prediction of D PK was not confirmed in this study. The Antipyrine Clearance test may be superior in this regard for D, but regimen dependent and hence warrants further evaluation.

No significant financial relationships to disclose.

Ball valve obstruction of a bronchus causing lobar emphysema in a neonate

Lobar emphysema in the neonate is usually congenital, resulting from cartilage deficiency causing bronchomalacia and distal air trapping. Acquired forms are usually associated with chronic lung disease or endobronchial obstruction such as mucus plugging. We report a pedunculated endobronchial polyp in a 2-month old ex-premature infant causing intermittent hyperinflation of the right middle lobe. The polyp was seen prolapsing in and out of the bronchus intermedius at bronchoscopy. Possible aetiological links with mechanical ventilation are discussed. We also emphasise the value of bronchoscopy prior to lobectomy in cases of congenital lobar emphysema (CLE).

Identification of candidate genes involved in neuroblastoma progression by combining genomic and expression microarrays with survival data

Identifying genes, whose expression is consistently altered by chromosomal gains or losses, is an important step in defining genes of biological relevance in a wide variety of tumour types. However, additional criteria are needed to discriminate further among the large number of candidate genes identified. This is particularly true for neuroblastoma, where multiple genomic copy number changes of proven prognostic value exist. We have used Affymetrix microarrays and a combination of fluorescent in situ hybridization and single nucleotide polymorphism (SNP) microarrays to establish expression profiles and delineate copy number alterations in 30 primary neuroblastomas. Correlation of microarray data with patient survival and analysis of expression within rodent neuroblastoma cell lines were then used to define further genes likely to be involved in the disease process. Using this approach, we identify >1000 genes within eight recurrent genomic alterations (loss of 1p, 3p, 4p, 10q and 11q, 2p gain, 17q gain, and the MYCN amplicon) whose expression is consistently altered by copy number change. Of these, 84 correlate with patient survival, with the minimal regions of 17q gain and 4p loss being enriched significantly for such genes. These include genes involved in RNA and DNA metabolism, and apoptosis. Orthologues of all but one of these genes on 17q are overexpressed in rodent neuroblastoma cell lines. A significant excess of SNPs whose copy number correlates with survival is also observed on proximal 4p in stage 4 tumours, and we find that deletion of 4p is associated with improved outcome in an extended cohort of tumours. These results define the major impact of genomic copy number alterations upon transcription within neuroblastoma, and highlight genes on distal 17q and proximal 4p for downstream analyses. They also suggest that integration of discriminators, such as survival and comparative gene expression, with microarray data may be useful in the identification of critical genes within regions of loss or gain in many human cancers.

Imaging with FLT-PET demonstrates that PF-477736, an inhibitor of CHK1 kinase, overcomes a cell cycle checkpoint induced by gemcitabine in PC-3 xenografts

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Background: The development of strategies to monitor the molecular and cellular response to novel agents that target the cell cycle is vital to provide proof of mechanism and biological activity of these compounds. The protein kinase CHK1 is activated following DNA damage in the S and G2-phases of the cell cycle and mediates cell cycle arrest. In vitro studies demonstrate that inhibition of CHK1 can overcome cell cycle arrest induced by DNA damage and enhance cytotoxic activity of DNA damaging agents. In vivo studies show that combining DNA damaging agents with a CHK1 inhibitor potentiates antitumor activity. We hypothesize that functional imaging with 18F-fluorine-L-thymidine (FLT), a PET-tracer where tumor uptake is maximal in the S and G2 phases of the cell cycle can be used to non-invasively monitor the induction and therapeutic inhibition of a cell cycle checkpoint in vivo. Methods: Nude mice harbouring PC-3 xenografts were treated with vehicle controls, gemcitabine, the CHK1-inhibitor PF-477736 or gemcitabine + PF-477736. FLT-PET scans were performed and tumors harvested for ex-vivo biomarkers to assess S-phase, M-phase and DNA-repair. Results: Gemcitabine induced a 8.3 ±0.8 fold increase in tumoral uptake of FLT at 21 hours that correlated with a 3.3 ±0.2-fold increase in thymidine kinase activity and S-phase arrest as demonstrated by BrdU incorporation and elevated expression of cyclin-A. Treatment with PF-477736 at 17 hours after gemcitabine abrogated the early FLT-flare at 21 hours by 82% (p<0.001). This was associated with both an increased fraction of cells in mitosis and G1-phase of the cell cycle as determined by phos-histone H3 and flow cytometry. Furthermore, the combination of gemcitabine and PF-477736 enhanced DNA damage as measured by phos-gamma-H2AX and significantly delayed tumor growth when compared to tumors treated with gemcitabine alone. Conclusion: These data clearly indicate that the CHK1-inhibitor PF-477736 can overcome the cell cycle checkpoint induced by gemcitabine and increase associated DNA damage in tumors in-vivo. The PET studies indicate that functional imaging with FLT-PET is a promising strategy to monitor responses to therapeutic agents that target cell cycle checkpoints.

[Table: see text]

Long-term survival after spontaneous rupture of a malignant rhabdoid tumor of the liver

A 13-month-old girl presented with a large malignant rhabdoid liver tumor that ruptured soon after admission. Six years after an emergency right hepatectomy and subsequent chemotherapy (ifosfamide, vincristine, and actinomycin D), she remains well and disease free. Previously, these rare tumors invariably have been fatal and resistant to multimodal therapy. This is the first report of long-term survival of a patient with a malignant rhabdoid liver tumor.

Mitochondrial and nuclear DNA damage induced by sulphur mustard in keratinocytes

The extent and role of mitochondrial DNA damage in the mechanism of action of sulphur mustard (SM) is poorly understood. In this study, a combination of quantitative polymerase chain reaction and Southern hybridization was used to determine the levels of both total DNA adducts and DNA interstrand crosslinks in genomic and mitochondrial DNA isolated from normal human epidermal keratinocytes exposed to SM. The formation of both types of lesions occurred simultaneously in nuclear and mitochondrial DNA, however, SM produced significantly higher levels of both total adducts and crosslinks in genomic DNA than mitochondrial DNA. The total lesion frequency was 0.45 lesions/kb per 100 microM SM in the DHFR gene and 0.12 lesions/kb per 100 microM SM in the mitochondrial segment. Interstrand crosslinks occurred at a frequency of 0.28 crosslinks/10 kb per 100 microM SM in the DHFR gene and 0.05 crosslinks/10 kb per 100 microM SM in the mitochondrial segment. DNA interstrand crosslinks are thought to be the critical lesion produced by similar bi-functional alkylating agents. However, the levels of DNA cross-linking revealed in this study show that even at vesicating doses of SM mitochondrial DNA is still largely free of cross-links and the predominant form of DNA damage contributing to cell death occurs in the nucleus.

Comprehensive genetic and histopathologic study reveals three types of neuroblastoma tumors

PURPOSE

To determine the relationship between multiple genetic features, tumor morphology, and prognosis in neuroblastoma.

PATIENTS AND METHODS

The genetic alterations and morphologic features that underpin three histopathologic risk classifications were analyzed in 108 neuroblastoma patients. Tumors were subdivided into four groups based on the three most frequent and prognostically significant genetic alterations (17q gain, 1p deletion, and MYCN amplification), and all other genetic, morphologic, and clinical data were analyzed with respect to these groups.

RESULTS

Our analyses identify three nonoverlapping tumor types with distinct genetic and morphologic features, defined here as types 1, 2, and 3. Type 1 tumors show none of the three significant genetic alterations and have good prognosis. Both type 2 (17q gain only or 17q gain and 1p del) and type 3 (17q gain, 1p del, and MYCN amplification) tumors progress. However, these tumor types are distinguished clinically by having significantly different median age at diagnosis and median progression-free survival (PFS). Multivariate analysis indicates that 17q gain is the only independent prognostic factor among all genetic, histopathologic, and clinical factors analyzed. Among histopathologic risk systems, the International Neuroblastoma Pathology Classification was the best predictor of PFS.

CONCLUSION

Our results indicate that specific combinations of genetic changes in neuroblastoma tumors contribute to distinct morphologic and clinical features. Furthermore, the identification of two genetically and morphologically distinct types of progressing tumors suggests that possibilities for different therapeutic regimens should be investigated.

Synthesis, cytotoxicity, cell uptake and DNA interstrand cross-linking of 4,4'-dipyrazolylmethane-linked multinuclear platinum anti-cancer complexes

Two cationic multinuclear platinum complexes linked with the 4,4'-dipyrazolylmethane (dpzm) ligand, trans-[[Pt(NH3)2Cl]2-mu-dpzm]Cl2 (di-Pt) and trans-[trans-[Pt(NH3)2Cl]2[trans-[Pt(NH3)2(mu-dpzm)2]]]Cl4 (tri-Pt), have been synthesized. Both complexes show activity in the murine leukaemia cell line L1210 (IC50 = 3.8 and 2.5 microm, respectively) and the cisplatin-resistant subline L1210/DDP (8.8 and 3.6 microM), and in the human ovarian carcinoma 2008 (2.5 and 17.8 microM) and its cisplatin-resistant subline C13*5 (20.9 and 37.7 microM). Both complexes show high levels of uptake into 2008 cells, when administered at 100 microM, but significantly reduced uptake in the cisplatin-resistant cell line C13*5 (di-Pt, 66% decrease; tri-Pt, 42%; cisplatin, 86%). Both complexes form very high levels of DNA interstrand cross-links in vitro, with 50% interstrand cross-linking observed at far lower concentrations (di-Pt, 12 nM; tri-Pt, 22 nM) than cisplatin (450 nM). It is proposed that the higher extent of interstrand cross-linking may be due to the rigid nature of the dpzm linking ligand, which prevents the complexes from forming short-range intrastrand adducts, like the GpG adduct formed by cisplatin. The results of this study indicate the importance of the flexibility of the linking ligand for the cytotoxicity of di- and trinuclear platinum anti-cancer complexes.

Late mediastinal shift after repeated aspiration of postpneumonectomy seroma

Development of a postoperative seroma is a frequent complication after muscle-sparing thoracotomy. We describe an unusual case of late mediastinal shift in a patient in whom our original plan to perform a limited muscle-sparing thoracotomy was abandoned. The procedure was converted to a standard posterolateral incision to perform a pneumonectomy for a large central carcinoid tumor with extrabronchial extension. Fluid that accumulated in her pneumonectomy space presumably shifted into the dissected tissues of her chest wall, and was then drained repeatedly by her local physician in the time interval between 2 weeks and 3 months after surgery.

Relationship between histopathological features, MYCN amplification, and prognosis: a UKCCSG study. United Kingdom Children Cancer Study Group

Histological sections from 231 patients with neuroblastoma were reviewed and morphological features and their relationship to age, stage, MYCN amplification (in 128 tumours by Southern analyses), and clinical outcome (based on Shimada risk grouping) determined. Stage 4 disease was associated with poorly differentiated and undifferentiated tumours (P = 0.001), an MKI of >2% (P< 0.001), and Shimada unfavourable histology (UHi) P< 0.0001. In univariate analysis MKI was significant in predicting a poorer relapse-free survival (RFS), low vs. intermediate and high (P< 0.001). Age, MYCN amplification, and Shimada UH also emerged as significant variables. There was a higher proportion of MYCN-amplified tumours with Shimada UH (P = 0.03), and this group had a decreased RFS (P = 0.002). In patients with Shimada FH, MYCN amplification did not significantly predict a poor prognosis. In those with stage 4 disease, Shimada classification was not significant in predicting survival (P = 0.97); the same was true for those over the age of 1 year (P = 0.66). In multivariate analysis, MYCN amplification and Shimada UH both emerged as independent prognostic factors. In conclusion, morphological features assigned some subsets of patients to prognostic risk groups. Most MYCN-amplified tumours have unfavourable histology and a poorer prognosis. However, in patients with stage 4 disease and those over the age of 1 year, other factors that may influence prognosis should be determined.

DNA targeted platinum complexes: synthesis, cytotoxicity and DNA interactions of cis-dichloroplatinum(II) complexes tethered to phenazine-1-carboxamides

A series of intercalator-tethered platinum(II) complexes PtLCl2 have been prepared, where L are the diamine ligands N-[2-[(aminoethyl)amino]ethyl]-phenazine-1-carboxamide, N-[3-[(2-aminoethyl)amino]propyl]-phenazine-1-carboxamide, N-[4-[(2-aminoethyl)amino]butyl]-phenazine-1-carboxamide and N-[5-[(aminoethyl)amino]pentyl]-phenazine-1-carboxamide. Measurements of the time-course of unwinding of supercoiled pUC19 plasmid DNA by the phenazine complexes PtLCl2 reveal that the presence of the intercalator leads to enhanced rates of DNA platination when compared with the complex Pt(en)Cl2. The platinum(II) complexes where the polymethylene linker chain contains three, four or five carbon atoms are considerably more cytotoxic against murine P388/W than either cisplatin, Pt(en)Cl2, or the metal-free ligands themselves.

Adriamycin-induced inhibition of mitochondrial-encoded polypeptides as a model system for the identification of hotspots for DNA-damaging agents

It has recently been shown that the anti-cancer drug Adriamycin forms drug-DNA adducts which function as 'virtual' interstrand cross-links in cells, and these cross-links are specific for GpC sequences. The objective of this work was to determine whether all GpC sites are equally susceptible to the formation of Adriamycin-DNA adducts in the mitochondrial genome or whether any 'hotspots' exist whereby lesions are formed preferentially at particular GpC-containing sequences. The mitochondrial genome was used as a model system as it provides a series of contiguous genes, all of which lack introns and in which transcription is driven from a single promoter. With the absence of nucleotide excision repair, this provides an excellent system with which to observe Adriamycin-induced DNA damage since such lesions are reflected as an inhibition of mitochondrial protein synthesis. HeLa cells were treated with Adriamycin and the extent to which synthesis of individual mitochondrial-encoded proteins was inhibited was quantitated. Mitochondrial protein synthesis was found to be inhibited in a discontinuous manner, corresponding to regions rich in 5'-GpC sequences. These results therefore indicate that Adriamycin-DNA adducts do not form randomly with GpC sites throughout the mitochondrial genome, but instead appear to form preferentially at regions of high GpC content. This selective inhibition of mitochondrial-encoded proteins demonstrates the potential of this method for the in situ detection of localized regions of binding by DNA-acting drugs.

Transcriptional blockages in a cell-free system by sequence-selective DNA alkylating agents

There is considerable interest in DNA sequence-selective DNA-binding drugs as potential inhibitors of gene expression. Five compounds with distinctly different base pair specificities were compared in their effects on the formation and elongation of the transcription complex from the lac UV5 promoter in a cell-free system. All were tested at drug levels which killed 90% of cells in a clonogenic survival assay. Cisplatin, a selective alkylator at purine residues, inhibited transcription, decreasing the full-length transcript, and causing blockage at a number of GG or AG sequences, making it probable that intrastrand crosslinks are the blocking lesions. A cyclopropylindoline known to be an A-specific alkylator also inhibited transcription, with blocks at adenines. The aniline mustard chlorambucil, that targets primarily G but also A sequences, was also effective in blocking the formation of full-length transcripts. It produced transcription blocks either at, or one base prior to, AA or GG sequences, suggesting that intrastrand crosslinks could again be involved. The non-alkylating DNA minor groove binder Hoechst 33342 (a bisbenzimidazole) blocked formation of the full-length transcript, but without creating specific blockage sites. A bisbenzimidazole-linked aniline mustard analogue was a more effective transcription inhibitor than either chlorambucil or Hoechst 33342, with different blockage sites occurring immediately as compared with 2 h after incubation. The blockages were either immediately prior to AA or GG residues, or four to five base pairs prior to such sites, a pattern not predicted from in vitro DNA-binding studies. Minor groove DNA-binding ligands are of particular interest as inhibitors of gene expression, since they have the potential ability to bind selectively to long sequences of DNA. The results suggest that the bisbenzimidazole-linked mustard does cause alkylation and transcription blockage at novel DNA sites. in addition to sites characteristic of untargeted mustards.

Formaldehyde activation of mitoxantrone yields CpG and CpA specific DNA adducts

Recently we have found that mitoxantrone, like Adria-mycin, can be activated by formaldehyde and subsequently form adducts which stabilise double-stranded DNA in vitro. This activation by formaldehyde may be biologically relevant since formaldehyde levels are elevated in those tumours in which mitoxan-trone is most cytotoxic. In vitro transcription analysis revealed that these adducts block the progression of RNA polymerase during transcription and cause truncated RNA transcripts. There was an absolute requirement for both mitoxantrone and formaldehyde in transcriptional blockage formation and the activated complex was found to exhibit site specificity, with blockage occurring prior to CpG and CpA sites in the DNA (non-template strand). The stability of the adduct at 37 degrees C was site dependent. The half-lives ranged from 45 min to approximately 5 h and this was dependent on both the central 2 bp blockage site as well as flanking sequences. The CpG specificity of mitoxantrone adduct sites was also confirmed independently by a lambda exonuclease digestion assay.