Activation of a cGAS-STING-mediated immune response predicts response to neoadjuvant chemotherapy in early breast cancer.

BACKGROUND: The DNA-damage immune-response (DDIR) signature is an immune-driven gene expression signature retrospectively validated as predicting response to anthracycline-based therapy. This feasibility study prospectively evaluates the use of this assay to predict neoadjuvant chemotherapy response in early breast cancer. METHODS: This feasibility study assessed the integration of a novel biomarker into clinical workflows. Tumour samples were collected from patients receiving standard of care neoadjuvant chemotherapy (FEC + /-taxane and anti-HER2 therapy as appropriate) at baseline, mid- and post-chemotherapy. Baseline DDIR signature scores were correlated with pathological treatment response. RNA sequencing was used to assess chemotherapy/response-related changes in biologically linked gene signatures. RESULTS: DDIR signature reports were available within 14 days for 97.8% of 46 patients (13 TNBC, 16 HER2 + ve, 27 ER + HER2-ve). Positive scores predicted response to treatment (odds ratio 4.67 for RCB 0-1 disease (95% CI 1.13-15.09, P = 0.032)). DDIR positivity correlated with immune infiltration and upregulated immune-checkpoint gene expression. CONCLUSIONS: This study validates the DDIR signature as predictive of response to neoadjuvant chemotherapy which can be integrated into clinical workflows, potentially identifying a subgroup with high sensitivity to anthracycline chemotherapy. Transcriptomic data suggest induction with anthracycline-containing regimens in immune restricted, "cold" tumours may be effective for immune priming. TRIAL REGISTRATION: Not applicable (non-interventional study). CRUK Internal Database Number 14232.

Student experiences in an academic support program to diversify the nursing workforce.

BACKGROUND: The current demographic of the Nursing workforce in the United States suggests a need to increase the percentage of minority nurses in practice. Diversifying the nursing workforce may change patient perceptions and improve the quality of care received by underserved patients. A college of nursing created the Nursing Endeavor Program to support first generation, low income, and/or underrepresented students from the point of acceptance in the nursing program to graduation. Nursing Endeavor students are guaranteed acceptance into the nursing major upon successful completion of these preliminary nursing courses. Despite application of some Jeffreys interventions, only 50% of Nursing Endeavor students enrolled in the preliminary nursing courses qualified to enter the major and graduated. One hundred percent of all Nursing Endeavor students who successfully transitioned into the final two years of the major had graduated. Therefore, this study focused on the efficacy of NEP interventions to support students in the first two years. OBJECTIVES: The aim of this study was to analyze student perspectives of the efficacy of interventions in the Nurse Endeavor Program designed to facilitate successful completion of the first two years of preliminary courses in the nursing major, which equates to a successful transition to student nurse. DESIGN: This study used a Qualitative Phenomenographic research design. SETTINGS: Individual interviews were conducted in the Principal Investigator's office in a Midwestern United States Research Universities' College of Nursing. PARTICIPANTS: Eleven students who continued in the Nursing Endeavor Program to graduation, and eight former Nursing Endeavor students who withdrew from the nursing major during preliminary nursing courses. METHODS: Meleis transitions theory guided the study design. Institutional Review Board approval for study 17.272, and participant consent were obtained. Face-to-face interviews were conducted in the Principal Investigator's office and were transcribed verbatim. Phenomenographic methods were used for narrative analysis. RESULTS: Students reported nine interventions facilitated transition from preliminary nursing courses to the nursing major. Students reported three factors hindered transition: academic rigor, isolation, and living at home. Attendance at professional events was not mentioned. CONCLUSIONS: Students credited Jeffreys' interventions for successful transitions. Additional factors influencing transition identified by students merit further study.

Towards trauma-informed legal practice: a review.

Vicarious or secondary trauma experience has always been part of legal practice although many do not acknowledge the risk it can have on the mental health, well-being and performance of legal professionals. The listening to, observing and then detailing of traumatic events for the purposes of legal process in some cases may harm lawyers who need to work closely with clients, victims and witnesses. This article reviews the research on trauma in many areas of professional human services that could inform and improve our understanding of legal practice. It examines the discursive history of trauma and recent studies on lawyer well-being, before discussing the controversies about recognising vicarious trauma and the stigma against mental health concerns in the legal profession. The article concludes by reviewing options to assist law firms in considering trauma-informed policy, practices and supervision strategies and to help individual lawyers recognise the value of self-care.

Evidence-Based Interventions for Retention of Nursing Students: A Review of the Literature.

BACKGROUND: There is a need to better understand effective student retention strategies in nursing. PURPOSE: This review of course and program interventions reported in the nursing literature is intended to highlight interventions, supported by evidence, to graduate more enrolled students and recommend areas of retention efforts that need further research. METHODS: The PRISMA search strategy was used to identify and narrow the number of relevant studies. A scoring instrument to evaluate rigor, reliability, and validity of interventions was adapted from a valid and reliable tool used to evaluate studies using a health care education intervention. RESULTS: Evidence-based interventions that improved retention included retention program/specialist, robust orientation, mentoring and tutoring, stipends, and remediation. CONCLUSION: Nurse educators are independently striving to improve retention rates of nursing students. Implementing evidence-based interventions will advance this effort.

Rabies in the Caribbean: A Situational Analysis and Historic Review.

Rabies virus is the only Lyssavirus species found in the Americas. In discussions about rabies, Latin America and the Caribbean are often grouped together. Our study aimed to independently analyse the rabies situation in the Caribbean and examine changes in rabies spatiotemporal epidemiology. A questionnaire was administered to the 33 member countries and territories of the Caribbean Animal Health Network (CaribVET) to collect current data, which was collated with a literature review. Rabies was endemic in ten Caribbean localities, with the dog, mongoose, and vampire bat identified as enzootic reservoirs. The majority of animal cases occurred in Puerto Rico, the Dominican Republic, and Haiti, while human cases only consistently occurred in the latter two areas. Rabies vaccination was conducted for high-risk animal populations with variable coverage, and rabies diagnostic capacities varied widely throughout the region. Illegal importation and natural migration of animals may facilitate the introduction of rabies virus variants into virus-naïve areas. Passive surveillance, together with enhanced methods and serological screening techniques, can therefore be of value. The insularity of the Caribbean makes it ideal for conducting pilot studies on reservoir host population management. Best practice guidelines developed for these reservoir hosts can be individually modified to the epidemiological status and available resources within each locality.

Using spatial-stream-network models and long-term data to understand and predict dynamics of faecal contamination in a mixed land-use catchment.

An 11year dataset of concentrations of E. coli at 10 spatially-distributed sites in a mixed land-use catchment in NE Scotland (52km2) revealed that concentrations were not clearly associated with flow or season. The lack of a clear flow-concentration relationship may have been due to greater water fluxes from less-contaminated headwaters during high flows diluting downstream concentrations, the importance of persistent point sources of E. coli both anthropogenic and agricultural, and possibly the temporal resolution of the dataset. Point sources and year-round grazing of livestock probably obscured clear seasonality in concentrations. Multiple linear regression models identified potential for contamination by anthropogenic point sources as a significant predictor of long-term spatial patterns of low, average and high concentrations of E. coli. Neither arable nor pasture land was significant, even when accounting for hydrological connectivity with a topographic-index method. However, this may have reflected coarse-scale land-cover data inadequately representing "point sources" of agricultural contamination (e.g. direct defecation of livestock into the stream) and temporal changes in availability of E. coli from diffuse sources. Spatial-stream-network models (SSNMs) were applied in a novel context, and had value in making more robust catchment-scale predictions of concentrations of E. coli with estimates of uncertainty, and in enabling identification of potential "hot spots" of faecal contamination. Successfully managing faecal contamination of surface waters is vital for safeguarding public health. Our finding that concentrations of E. coli could not clearly be associated with flow or season may suggest that management strategies should not necessarily target only high flow events or summer when faecal contamination risk is often assumed to be greatest. Furthermore, we identified SSNMs as valuable tools for identifying possible "hot spots" of contamination which could be targeted for management, and for highlighting areas where additional monitoring could help better constrain predictions relating to faecal contamination.

Evaluation of the taste-masking effects of (2-hydroxypropyl)-ß-cyclodextrin on ranitidine hydrochloride; a combined biosensor, spectroscopic and molecular modelling assessment.

Taste assessment in an increasingly important aspect of formulation development, particularly for paediatric medications. Electronic taste sensing systems have the potential to offer a rapid, objective and safe method of taste assessment prior to the use of more costly human panels or animal models. In this study, the ability of the TS-5000Z taste sensing system to assess the taste masking efficiency of (2-hydroxypropyl)-ß-cyclodextrin (HP-ß-CyD) complexes with ranitidine hydrochloride was evaluated in order to explore the potential of the biosensor approach as a means of assessing taste masking by inclusion complexation. Nuclear magnetic resonance (NMR) spectroscopy and molecular docking studies were employed to identify and examine the interaction between ranitidine hydrochloride and HP-ß-CyD. Taste-masking efficiencies were determined by the Euclidean distance between taste-masked formulations and the pure drug substance on a PCA score plot. The results showed that with increasing molarity of HP-ß-CyD in the formulation, the distance from ranitidine hydrochloride increased, thus indicating a significant difference between the taste of the formulation and that of the pure drug. NMR studies also provided strong supporting evidence for the complexation between HP-ß-CyD and ranitidine hydrochloride, with the H3' region of the former identified as the most likely binding site for the drug. Molecular docking studies suggested that the dimethylamino and diamine groups of the drug form direct hydrogen bonds with the hydroxyl oxygen atoms of HP-ß-CyD, while the furan ring docks in close proximity to H3'. This study has demonstrated that the biosensor system may provide quantitative data to assess bitterness of inclusion complexes with HP-ß-CyD, while spectroscopic and modelling studies may provide a mechanistic explanation for the taste masking process. This in turn suggests that there is a role for biosensor approaches in providing early screening for taste masking using inclusion complexation and that the combination with mechanistic studies may provide insights into the molecular basis of taste and taste masking.

The culture of pretence: a hidden barrier to recognising, disclosing and ending domestic violence.

AIMS AND OBJECTIVES: To explore in detail how women perceived their experience of domestic violence and leaving or ending the abuse. This research also examined how service providers identified their professional role in assisting women to end such relationships. BACKGROUND: Domestic violence against women continues to occur internationally. Reliable statistics are difficult to capture because of inconsistent definitions, contradictory methods of acquiring data and unreported incidents. DESIGN: A qualitative study, undertaken in two phases, was conducted in Australia. METHODS: Twelve women who had experienced domestic violence and ended those relationships participated in one semistructured interview (Phase 1). Twenty-five professionals from health, social sciences and law, whose work included assisting women experiencing domestic violence, participated in three focus groups (Phase 2). Thematic analysis guided by a narrative inquiry approach forms the framework for information collection and interpretation of data in this project. FINDINGS: The barriers that impede women from disclosing abuse and taking action to end domestic violence are complex and varied between participants. Women did not always acknowledge or realise their relationship was precarious and often denied or minimised the abuse to cope with the domestic violence. Professionals identified that women did not always identify or acknowledge abuse inherent in their relationship although this delayed the provision of appropriate services. CONCLUSION: Whether women disclose abuse or deny violence in their relationship, acceptance by service providers and the offer of support is crucial to assisting women in violent relationships. RELEVANCE TO CLINICAL PRACTICE: It is hoped that the findings may assist health practitioners, including nurses, to provide nonjudgemental support to women experiencing domestic violence whether women acknowledge the abusive relationship or not.

Thromboxane A2 receptor (TBXA2R) is a potent survival factor for triple negative breast cancers (TNBCs).

Triple Negative Breast Cancer (TNBC) is defined by the lack of ERα, PR expression and HER2 overexpression and is the breast cancer subtype with the poorest clinical outcomes. Our aim was to identify genes driving TNBC proliferation and/or survival which could represent novel therapeutic targets.We performed microarray profiling of primary TNBCs and generated differential genelists based on clinical outcomes following the chemotherapy regimen FEC (5-Fluorouracil/Epirubicin/Cyclophosphamide -'good' outcome no relapse > 3 years; 'poor' outcome relapse < 3 years). Elevated expression of thromboxane A2 receptor (TBXA2R) was observed in 'good' outcome TNBCs. TBXA2R expression was higher specifically in TNBC cell lines and TBXA2R knockdowns consistently showed dramatic cell killing in TNBC cells. TBXA2R mRNA and promoter activities were up-regulated following BRCA1 knockdown, with c-Myc being required for BRCA1-mediated transcriptional repression.We demonstrated that TBXA2R enhanced TNBC cell migration, invasion and activated Rho signalling, phenotypes which could be reversed using Rho-associated Kinase (ROCK) inhibitors. TBXA2R also protected TNBC cells from DNA damage by negatively regulating reactive oxygen species levels. In summary, TBXA2R is a novel breast cancer-associated gene required for the survival and migratory behaviour of a subset of TNBCs and could provide opportunities to develop novel, more effective treatments.

Synthesis, anti-mycobacterial activity and DNA sequence-selectivity of a library of biaryl-motifs containing polyamides.

The alarming rise of extensively drug-resistant tuberculosis (XDR-TB) strains, compel the development of new molecules with novel modes of action to control this world health emergency. Distamycin analogues containing N-terminal biaryl-motifs 2(1-5)(1-7) were synthesised using a solution-phase approach and evaluated for their anti-mycobacterial activity and DNA-sequence selectivity. Thiophene dimer motif-containing polyamide 2(2,6) exhibited 10-fold higher inhibitory activity against Mycobacterium tuberculosis compared to distamycin and library member 2(5,7) showed high binding affinity for the 5'-ACATAT-3' sequence.

Effect of hairpin loop structure on reactivity, sequence preference and adduct orientation of a DNA-interactive pyrrolo[2,1-c][1,4]benzodiazepine (PBD) antitumour agent.

The pyrrolobenzodiazepines (PBDs) are a family of covalent-binding DNA-interactive minor-groove binding agents with a thermodynamic preference for binding to 5'-Pu-G-Pu-3' sequences (Pu = Purine) but a kinetic preference for 5'-Py-G-Py-3' (Py = Pyrimidine). Using HPLC/MS methodology and a range of designed hairpin-forming oligonucleotides, the kinetics of reaction of a C8-bis-pyrrole pyrrolobenzodiazepine (PBD) conjugate (GWL-78, 2) with sixteen isomeric oligonucleotides has been evaluated, each containing a single PBD binding site in one of two locations. The PBD-binding base-pair triplets were designed to include every possible combination of A and T bases adjacent to the covalently-reacting guanine, with the set of hairpins consisting of isomeric pairs containing the same sequence in the hairpin stem but with either hexaethylene glycol (HEG) or TTT loops. The PBD 2 reacted most rapidly with TGT and TGA sequences, with the possibility that adducts might form in both the 3'- and 5'-directions with some sequences according to modelling studies. A faster reaction rate was observed for all hairpins containing the HEG loop except one (Seq 10) when the PBD binding triplets were located either near the loop or adjacent to the 5'-end. Modelling studies have suggested that this difference in reactivity could be due to the structural flexibility of the HEG loop allowing both A-ring-3' and A-ring-5' adducts to form, while a TTT loop should favour only A-ring-5' adducts due to steric considerations. These findings contrast with the results reported by Nguyen and Wilson for the interaction of non-covalent DNA-binding molecules with DNA hairpins, where the loop structure was found to have little effect on interaction in the main stem of the hairpin.

Computational studies support the role of the C7-sibirosamine sugar of the pyrrolobenzodiazepine (PBD) sibiromycin in transcription factor inhibition.

The pyrrolo[2,1-c][1,4]benzodiazepines (PBDs) are a group of sequence-selective, DNA minor-groove binding agents that covalently attach to guanine residues. Originally derived from Streptomyces species, a number of naturally occurring PBD monomers exist with varying A-Ring and C2-substituents. One such agent, sibiromycin, is unusual in having a glycosyl residue (sibirosamine) at its A-Ring C7-position. It is the most cytotoxic member of the naturally occurring PBD family and has the highest DNA-binding affinity. Recently, the analogue 9-deoxysibiromyin was produced biosynthetically by Yonemoto and co-workers.1 Differing only in the loss of the A-Ring C9-hydroxyl group, it was reported to have a significantly higher DNA-binding affinity than sibiromycin based on DNA thermal denaturation studies, although these data have since been retracted.2 As deletion of the C9-OH moiety, which points toward the DNA minor groove floor, might intuitively be expected to reduce DNA-binding affinity through the loss of hydrogen bonding, we carried out molecular dynamics simulations on the interaction of both molecules with DNA over a 10 ns time-course in explicit solvent. Our results suggest that the two molecules may differ in their sequence-selectivity and that 9-deoxysibiromycin should have a lower binding affinity for certain sequences of DNA compared to sibiromycin. Our molecular dynamics results indicate that the C7-sibirosamine sugar does not form hydrogen bonding interactions with groups in the DNA minor-groove wall as previously reported, but instead points orthogonally out from the minor groove where it may inhibit the approach of DNA control proteins such as transcription factors. This was confirmed through a docking study involving sibiromycin and the GAL4 transcription factor, and these results could explain the significantly enhanced cytotoxicity of sibiromycin compared to other PBD family members without bulky C7-substituents.

Identification and validation of an anthracycline/cyclophosphamide-based chemotherapy response assay in breast cancer.

BACKGROUND: There is no method routinely used to predict response to anthracycline and cyclophosphamide-based chemotherapy in the clinic; therefore patients often receive treatment for breast cancer with no benefit. Loss of the Fanconi anemia/BRCA (FA/BRCA) DNA damage response (DDR) pathway occurs in approximately 25% of breast cancer patients through several mechanisms and results in sensitization to DNA-damaging agents. The aim of this study was to develop an assay to detect DDR-deficient tumors associated with loss of the FA/BRCA pathway, for the purpose of treatment selection. METHODS: DNA microarray data from 21 FA patients and 11 control subjects were analyzed to identify genetic processes associated with a deficiency in DDR. Unsupervised hierarchical clustering was then performed using 60 BRCA1/2 mutant and 47 sporadic tumor samples, and a molecular subgroup was identified that was defined by the molecular processes represented within FA patients. A 44-gene microarray-based assay (the DDR deficiency assay) was developed to prospectively identify this subgroup from formalin-fixed, paraffin-embedded samples. All statistical tests were two-sided. RESULTS: In a publicly available independent cohort of 203 patients, the assay predicted complete pathologic response vs residual disease after neoadjuvant DNA-damaging chemotherapy (5-fluorouracil, anthracycline, and cyclophosphamide) with an odds ratio of 3.96 (95% confidence interval [Cl] =1.67 to 9.41; P = .002). In a new independent cohort of 191 breast cancer patients treated with adjuvant 5-fluorouracil, epirubicin, and cyclophosphamide, a positive assay result predicted 5-year relapse-free survival with a hazard ratio of 0.37 (95% Cl = 0.15 to 0.88; P = .03) compared with the assay negative population. CONCLUSIONS: A formalin-fixed, paraffin-embedded tissue-based assay has been developed and independently validated as a predictor of response and prognosis after anthracycline/cyclophosphamide-based chemotherapy in the neoadjuvant and adjuvant settings. These findings warrant further validation in a prospective clinical study.

An extended pyrrolobenzodiazepine-polyamide conjugate with selectivity for a DNA sequence containing the ICB2 transcription factor binding site.

The binding of nuclear factor Y (NF-Y) to inverted CCAAT boxes (ICBs) within the promoter region of DNA topoisomerase IIα results in control of cell differentiation and cell cycle progression. Thus, NF-Y inhibitory small molecules could be employed to inhibit the replication of cancer cells. A library of pyrrolobenzodiazepine (PBD) C8-conjugates consisting of one PBD unit attached to tri-heterocyclic polyamide fragments was designed and synthesized. The DNA-binding affinity and sequence selectivity of each compound were evaluated in DNA thermal denaturation and DNase I footprinting assays, and the ability to inhibit binding of NF-Y to ICB1 and ICB2 was studied using an electrophoretic mobility shift assay (EMSA). 3a was found to be a potent inhibitor of NF-Y binding, exhibiting a 10-fold selectivity for an ICB2 site compared to an ICB1-containing sequence, and showing low nanomolar cytotoxicity toward human tumor cell lines. Molecular modeling and computational studies have provided details of the covalent attachment process that leads to formation of the PBD-DNA adduct, and have allowed the preference of 3a for ICB2 to be rationalized.

GC-targeted C8-linked pyrrolobenzodiazepine-biaryl conjugates with femtomolar in vitro cytotoxicity and in vivo antitumor activity in mouse models.

DNA binding 4-(1-methyl-1H-pyrrol-3-yl)benzenamine (MPB) building blocks have been developed that span two DNA base pairs with a strong preference for GC-rich DNA. They have been conjugated to a pyrrolo[2,1-c][1,4]benzodiazepine (PBD) molecule to produce C8-linked PBD-MPB hybrids that can stabilize GC-rich DNA by up to 13-fold compared to AT-rich DNA. Some have subpicomolar IC50 values in human tumor cell lines and in primary chronic lymphocytic leukemia cells, while being up to 6 orders less cytotoxic in the non-tumor cell line WI38, suggesting that key DNA sequences may be relevant targets in these ultrasensitive cancer cell lines. One conjugate, 7h (KMR-28-39), which has femtomolar activity in the breast cancer cell line MDA-MB-231, has significant dose-dependent antitumor activity in MDA-MB-231 (breast) and MIA PaCa-2 (pancreatic) human tumor xenograft mouse models with insignificant toxicity at therapeutic doses. Preliminary studies suggest that 7h may sterically inhibit interaction of the transcription factor NF-κB with its cognate DNA binding sequence.

Determining the community prevalence of acute gastrointestinal illness and gaps in surveillance of acute gastroenteritis and foodborne diseases in Guyana.

Guyana is an English-speaking country in South America and, culturally, it is part of the Caribbean. Objective of this study was to determine the community prevalence and true burden and economic impact of acute gastroenteritis (AGE) and foodborne diseases (FBDs) in Guyana. A cross-sectional population-based survey was conducted in 7 of the 10 regions in Guyana during August and November 2009 to capture the high- and low-AGE season respectively. Overall, 1,254 individual surveys were administered at a response rate of 96.5%. The overall monthly prevalence of self-reported cases of AGE was 7.7% (97 cases) (95% CI 6.3-9.3), and the yearly incidence was 1.0 episodes per person-year. The highest monthly prevalence of AGE was observed in region 4 (8.9%) and in children aged 1-4 year(s) (12.7%). Of the 97 AGE cases, 23% sought medical care; 65% reported spending time at home due to their illness [range 1-20 day(s), mean 2.7 days], of whom 51% required other individuals to look after them while ill. The maximum number of stools per 24 hours ranged from 3 to 9 (mean 4.5), and number of days an individual suffered from AGE ranged from 1 to 21 day(s) (mean 2.7 days). The burden of syndromic AGE cases in the population for 2009 was estimated to be 131,012 cases compared to the reported 30,468 cases (76.7% underreporting), which implies that, for every syndromic case of AGE reported, there were additional 4.3 cases occurring in the community. For every laboratory-confirmed case of FBD/AGE pathogen reported, it was estimated that approximately 2,881 more cases were occurring in the population. Giardia was the most common foodborne pathogen isolated. The minimum estimated annual cost associated with the treatment for AGE was US$ 2,358,233.2, showing that AGE and FBD pose a huge economic burden on Guyana. Underreporting of AGE and foodbome pathogens, stool collection, and laboratory capacity were major gaps, affecting the surveillance of AGE in Guyana.

Antistaphylococcal activity of DNA-interactive pyrrolobenzodiazepine (PBD) dimers and PBD-biaryl conjugates.

OBJECTIVES: Pyrrolobenzodiazepine (PBD) dimers, tethered through inert propyldioxy or pentyldioxy linkers, possess potent bactericidal activity against a range of Gram-positive bacteria by virtue of their capacity to cross-link duplex DNA in sequence-selective fashion. Here we attempt to improve the antibacterial activity and cytotoxicity profile of PBD-containing conjugates by extension of dimer linkers and replacement of one PBD unit with phenyl-substituted or benzo-fused heterocycles that facilitate non-covalent interactions with duplex DNA. METHODS: DNase I footprinting was used to identify high-affinity DNA binding sites. A staphylococcal gene microarray was used to assess epidemic methicillin-resistant Staphylococcus aureus 16 phenotypes induced by PBD conjugates. Molecular dynamics simulations were employed to investigate the accommodation of compounds within the DNA helix. RESULTS: Increasing the length of the linker in PBD dimers led to a progressive reduction in antibacterial activity, but not in their cytotoxic capacity. Complex patterns of DNA binding were noted for extended PBD dimers. Modelling of DNA strand cross-linking by PBD dimers indicated distortion of the helix. A majority (26 of 43) of PBD-biaryl conjugates possessed potent antibacterial activity with little or no helical distortion and a more favourable cytotoxicity profile. Bactericidal activity of PBD-biaryl conjugates was determined by inability to excise covalently bound drug molecules from bacterial duplex DNA. CONCLUSIONS: PBD-biaryl conjugates have a superior antibacterial profile compared with PBD dimers such as ELB-21. We have identified six PBD-biaryl conjugates as potential drug development candidates.

Observation of a single-stranded DNA/pyrrolobenzodiazepine adduct.

Pyrrolobenzodiazepine (PBD) antitumor agents have, to date, only been observed to bind to duplex DNA, apparently requiring a minor groove environment for covalent bond formation between their C11-position and the C2-NH(2) functionality of a guanine base. Using an HPLC/MS assay we have now observed and isolated for the first time PBD adducts with single-stranded DNA fragments. Surprisingly, these adducts could only be formed through dissociation of duplex DNA adducts and not by direct interaction of PBDs with single-stranded DNA. They were sufficiently stable for characterization by MALDI-TOF-MS and remained intact after storing at -20 °C for at least 20 days, although the PBD became detached from the DNA within 7 days if stored at room temperature. Furthermore, addition of a complementary strand allowed the duplex adduct to reform. The relative stability of single-stranded PBD/DNA adducts despite a complete loss of minor groove structure was further confirmed by CD spectroscopic analysis. The CD signal induced by the presence of a PBD molecule in the single-stranded adducts remained prominent despite heating for 2 h at 50-60 °C, thus indicating their relatively robust nature.

Human epidermal growth factor receptor 2-positive breast cancer relapsing post-adjuvant trastuzumab: pattern of recurrence, treatment and outcome.

BACKGROUND: The purpose of this study is to evaluate the response to and benefit of first-line metastatic treatment (including re-exposure to trastuzumab) for patients relapsing after exposure to adjuvant trastuzumab (AT). PATIENTS AND METHODS: All HER2-positive breast cancer cases relapsing after exposure to AT at our institutions were identified. Clinico-pathologic details, pattern of relapse, and treatment in the metastatic setting were documented. Response to treatment and outcome were assessed. RESULTS: Twenty-nine relapses were recorded. The median time to relapse was 18.4 months from diagnosis, and 8.7 months from AT initiation. At a median time of observation of 9.9 months, 18 patients had progressed on first-line therapy. The median time-to-progression (TTP) was 8.6 months. Fifteen patients received trastuzumab as first-line treatment, with no statistical difference in TTP between this group and those not re-exposed to trastuzumab. TTP was not statistically different between those relapsing on or after AT. Overall survival was longer for those who relapsed after completion of 1 year of AT as well as those who received further trastuzumab at relapse; however, this did not reach statistical significance. CONCLUSION: Overall survival was longer in patients who relapse after completion of AT and who received further trastuzumab at progression.