APOBEC mutagenesis, kataegis, chromothripsis in EGFR-mutant osimertinib-resistant lung adenocarcinomas

BACKGROUND

Studies of targeted therapy resistance in lung cancer have primarily focused on single-gene alterations. Based on prior work implicating apolipoprotein b mRNA-editing enzyme, catalytic polypeptide-like (APOBEC) mutagenesis in histological transformation of epidermal growth factor receptor (EGFR)-mutant lung cancers, we hypothesized that mutational signature analysis may help elucidate acquired resistance to targeted therapies.

PATIENTS AND METHODS

APOBEC mutational signatures derived from an Food and Drug Administration-cleared multigene panel [Memorial Sloan Kettering Cancer Center Integrated Mutation Profiling of Actionable Cancer Targets (MSK-IMPACT)] using the Signature Multivariate Analysis (SigMA) algorithm were validated against the gold standard of mutational signatures derived from whole-exome sequencing. Mutational signatures were decomposed in 3276 unique lung adenocarcinomas (LUADs), including 93 paired osimertinib-naïve and -resistant EGFR-mutant tumors. Associations between APOBEC and mechanisms of resistance to osimertinib were investigated. Whole-genome sequencing was carried out on available EGFR-mutant lung cancer samples (10 paired, 17 unpaired) to investigate large-scale genomic alterations potentially contributing to osimertinib resistance.

RESULTS

APOBEC mutational signatures were more frequent in receptor tyrosine kinase (RTK)-driven lung cancers (EGFR, ALK, RET, and ROS1; 25%) compared to LUADs at large (20%, P < 0.001); across all subtypes, APOBEC mutational signatures were enriched in subclonal mutations (P < 0.001). In EGFR-mutant lung cancers, osimertinib-resistant samples more frequently displayed an APOBEC-dominant mutational signature compared to osimertinib-naïve samples (28% versus 14%, P = 0.03). Specifically, mutations detected in osimertinib-resistant tumors but not in pre-treatment samples significantly more frequently displayed an APOBEC-dominant mutational signature (44% versus 23%, P < 0.001). EGFR-mutant samples with APOBEC-dominant signatures had enrichment of large-scale genomic rearrangements (P = 0.01) and kataegis (P = 0.03) in areas of APOBEC mutagenesis.

CONCLUSIONS

APOBEC mutational signatures are frequent in RTK-driven LUADs and increase under the selective pressure of osimertinib in EGFR-mutant lung cancer. APOBEC mutational signature enrichment in subclonal mutations, private mutations acquired after osimertinib treatment, and areas of large-scale genomic rearrangements highlights a potentially fundamental role for APOBEC mutagenesis in the development of resistance to targeted therapies, which may be potentially exploited to overcome such resistance.

Setting targets for population health improvements: Trends in perinatal health in Europe over the past five years

Background

The Euro-Peristat network documented disparities in perinatal outcomes between countries in Europe in its reports published every 5 years, but trend analyses were limited because data were not collected annually.

Methods

Using the Euro-Peristat PHIRI protocol, we estimated rates and assessed trends between 2015 and 2019 for preterm birth, stillbirth, neonatal mortality and caesarean delivery. Country-specific relative risks (RR) for year, modelled as a continuous variable, were estimated and random effects meta-analysis used to generate pooled RRs. Heterogeneity was measured with the I2 statistic (percentage of variability in estimates due to heterogeneity rather than sampling error).

Results

Stillbirth rates ≥24 weeks of gestational age (GA) varied in 2019 from &lt;2.5 per 1000 births in Denmark, Estonia, Finland and Slovenia to over 4 per 1000 in Belgium, Cyprus, UK Wales and Lithuania. Preterm birth rates ranged from &lt;6% in Lithuania, Finland, Latvia, Estonia and Denmark to 8% or more in Portugal, Belgium, UK Scotland and Cyprus. Fewer than 20% of births were by caesarean in Norway, the Netherlands, Finland, Estonia in comparison to one-third in Cyprus, Ireland, Italy, UK Scotland. Trends over time differed between countries and were not related to the level of the indicator: the pooled RR by year for preterm birth was 0.99 [0.99; 1.00] with five countries having significant decreases and three countries having increases. Caesarean section rates were stable overall (RR: 1.00 [0.99; 1.01]RR:1.00, 95% CI: 0.99-1.01), but with high heterogeneity (I2=99%); in six countries rates increased significantly, whereas in nine rates decreased between 2015 and 2019.

Conclusions

European countries have varying rates and trends of the principal perinatal health indicators. Investigation of policies in high-performing countries could provide guidance for improvement elsewhere.

OS03.5.A Characterization of the inflammatory tumor microenvironment composition in solid cancer patients with brain metastases after progression to immune checkpoint inhibitor therapy

Background

Immunotherapy (IO) has changed the treatment landscape of metastatic cancer patients, however, treatment resistance is frequent. We aimed to characterize the inflammatory tumor microenvironment in brain metastases (BM) after IO to gain a deeper understanding of immunologic escape mechanisms.

Material and Methods

Solid cancer patients who had BM resection after IO progression (IO cohort) were retrospectively identified. We analyzed tumor-infiltrating immune cell subsets (CD3, CD8, CD45RO, FOXP3) and expression of immune checkpoint molecules (PD-L1, PD-1, LAG-3) by immunohistochemistry. A control cohort of BM tissue samples without prior IO served for comparison (no immunotherapy cohort, NIO).

Results

Twenty-eight IO patients (12/28, 42.9% females; 16/28, 57.1% males; median 61 years; 14/28, 50% lung cancer; 5/28, 17.9% melanoma; 4/28, 14.3% renal cell carcinoma; 1/28, 3.6% breast cancer; 4/28, 14.3% other cancer entities) and 57 NIO patients (28/57, 49.1% females; 29/57, 50.9% males; median 58 years; 35/57, 61.4% lung cancer; 9/57, 15.8% breast cancer; 4/57, 7.0% melanoma; 3/57, 5.3% renal cell carcinoma; 6/57, 10.5% other cancer entities) were included. IO patients had a median of one (range 0-4) systemic therapy line prior to IO. Median time from last IO application until BM resection was 5.6 months (range 0.2-49.8 months). Patients received a median number of 7 (range 1-56) IO applications (14/28, 50% PD-1-targeting IO; 8/28, 28.6% PD-L1; 2/28, 7.1% CTLA4; 4/28, 14.3% CTLA4+PD-1; 3/28, 10.7% IO+chemotherapy). No statistically significant differences in the densities of investigated TILs or PD-L1 expression between the IO and the NIO cohort were observed. Patients of the IO cohort showed higher PD-L1 expression compared to the NIO cohort (57.1 vs. 42.1%, Chi-square, p&gt;0.05). Overall survival (OS) was similar in both cohorts, with a median OS of 11.0 months (range 5.0-17.0) in the IO cohort and 11.0 months (range 5.5-16.5) in the NIO cohort.

Conclusion

Our findings show an upregulation of PD-L1 in BM occurring after prior IO therapy in the absence of other overt changes in the inflammatory microenvironment. Ongoing analyses in this cohort are investigating possible molecular driver of resistance by analyzing DNA methylation profiles of pre-and post-IO tissue samples of the IO cohort to potentially gain insights on inflammatory IO resistance mechanisms in BM patients.

P11.27.B Whole genome DNA methylation as predictive biomarker in CNS WHO grade 2 and 3 oligodendroglioma patients receiving early postoperative treatment

Background

Oligodendrogliomas are glial tumors with a relatively favorable survival prognosis of &gt;10 years. While immediate postoperative treatment prolongs survival, long-term toxicities of adjuvant radio-chemotherapy remain a concern. Predictive biomarkers guiding postoperative treatment decisions are limited.

Material and Methods

In this retrospective study, we included patients treated for a newly diagnosed oligodendroglioma (isocitrate dehydrogenase (IDH)-mutated, 1p/19q-codeleted, CNS WHO grades 2 and 3) in 1992 - 2019 at the Medical University of Vienna or the Kepler University Hospital Linz (Austria). Early treatment was defined as radiotherapy, chemotherapy, or both within 6 months after resection, whereas benefit from early treatment was defined as progression-free survival (PFS) above the median in the overall cohort. DNA methylation analysis was performed using Illumina MethylationEPIC 850k microarrays.

Results

Of all 201 eligible patients, sufficient tumor tissue for DNA methylation analysis was available in 46 patients. Of these, 25/46 (54.3%) were diagnosed with CNS WHO grade 2 and 21/46 (45.6%) with grade 3 oligodendroglioma. Median age at diagnosis was 41 years (range: 23-70). In total, 21/46 (45.6%) patients received early treatment, of whom 13/21 (61.9%) received radio-chemotherapy, 6/21 (28.6%) radiotherapy only and 2/21 (9.5%) chemotherapy only. Median PFS was 134.0 months (95%CI: 78.3 - not reached) in patients receiving early treatment versus 87.2 months (95%CI: 66.8 - 150) in patients who did not. In patients receiving early treatment, differences in DNA methylation profiles could be detected between patients who drew benefit from postoperative treatment (group 1) versus those who did not (group 2). Based on the top 1000 differentially methylated CpG sites between both groups, two clusters were detected which comprised either patients of group 1 or 2. Clustering was independent from gender, WHO grade, extent of resection, type of postoperative treatment, treating center, and O6-methylguanine-methyltransferease (MGMT) promoter methylation status. Gene set enrichment analysis of the top 1000 differentially methylated gene sites mapped to 694 genes showed differential methylation in genes involved in fibroblast growth receptor 1 (FGFR1) signaling, Wnt signaling, integrin signaling, and actin cytoskeleton regulation. Conversely, in patients not receiving early treatment, PFS did neither correlate with DNA methylation clustering nor with MGMT promoter methylation.

Conclusion

In our cohort, whole genome DNA methylation was associated with PFS in patients who received early postoperative treatment, suggesting a predictive but not prognostic role. As the predictive value of MGMT promoter methylation is limited in oligodendroglioma, whole genome DNA methylation should be considered in future clinical trials.

Core-binding factor leukemia hijacks the T-cell-prone PU.1 antisense promoter

The blood system serves as a key model for cell differentiation and cancer. It is orchestrated by precise spatiotemporal expression of crucial transcription factors. One of the key master regulators in the hematopoietic systems is PU.1. Reduced levels of PU.1 are characteristic for human acute myeloid leukemia (AML) and are known to induce AML in mouse models. Here, we show that transcriptional downregulation of PU.1 is an active process involving an alternative promoter in intron 3 that is induced by RUNX transcription factors driving noncoding antisense transcription. Core-binding factor (CBF) fusions RUNX1-ETO and CBFβ-MYH11 in t(8;21) and inv(16) AML, respectively, activate the PU.1 antisense promoter that results in a shift from sense toward antisense transcription and myeloid differentiation blockade. In patients with CBF-AML, we found that an elevated antisense/sense transcript and promoter accessibility ratio represents a hallmark compared with normal karyotype AML or healthy CD34+ cells. Competitive interaction of an enhancer with the proximal or the antisense promoter forms a binary on/off switch for either myeloid or T-cell development. Leukemic CBF fusions thus use a physiological mechanism used by T cells to decrease sense transcription. Our study is the first example of a sense/antisense promoter competition as a crucial functional switch for gene expression perturbation by oncogenes. Hence, this disease mechanism reveals a previously unknown Achilles heel for future precise therapeutic targeting of oncogene-induced chromatin remodeling.

Tumor mutational burden and immune infiltrates in renal cell carcinoma and matched brain metastases

BACKGROUND

Tumor mutational burden (TMB) and density of tumor-infiltrating lymphocytes (TIL) have been postulated as predictive biomarkers for immunotherapy. Therefore, we investigated the concordance of TMB and TIL of primary/extracranial renal cell carcinoma (RCC) specimens and matched brain metastases (BM).

PATIENTS AND METHODS

Twenty specimens from 10 patients were retrieved from the Vienna Brain Metastasis Registry (6/10 primary tumor, 4/10 lung metastasis, 10/10 matched BM). TMB was assessed using the TruSight Oncology 500 gene panel with libraries sequenced on a NextSeq instrument. TIL subsets (CD3+, CD8+, CD45RO+, FOXP3+, PD-L1+) were investigated using immunohistochemistry (Ventana Benchmark Ultra system) and automated tissue analysis (Definiens software).

RESULTS

No significant difference in TMB, CD3+, CD8+, CD45RO+, FOXP3+ or PD-L1+ expression was observed between extracranial and matched intracranial specimens (P > 0.05). Higher CD8+ TIL (P = 0.053) and CD45RO+ TIL (P = 0.030) densities in the primary tumor compared with the intracranial samples were observed in specimens collected after exposure to systemic treatment. Neither extracranial sample origin (lung metastasis versus primary RCC) nor extracranial disease status at BM diagnosis (progressive versus stable disease) were significantly associated with TMB or TIL densities in extracranial and intracranial samples (P > 0.05). No significant correlation was found between the median differences of TMB or TIL densities from extracranial to intracranial samples and BM-free survival.

CONCLUSION

The comparable immunological microenvironment of extra- and intracranial tumor samples in our study underscores the immunological activation also in BM from RCC, and therefore, supports the development of immune modulatory treatments also in patients with brain metastatic RCC.

Using Robson's Ten-Group Classification System for comparing caesarean section rates in Europe: an analysis of routine data from the Euro-Peristat study

Objective

Robson's Ten Group Classification System (TGCS) creates clinically relevant sub‐groups for monitoring caesarean birth rates. This study assesses whether this classification can be derived from routine data in Europe and uses it to analyse national caesarean rates.

Design

Observational study using routine data.

Setting

Twenty‐seven EU member states plus Iceland, Norway, Switzerland and the UK.

Population

All births at ≥22 weeks of gestational age in 2015.

Methods

National statistical offices and medical birth registers derived numbers of caesarean births in TGCS groups.

Main outcome measures

Overall caesarean rate, prevalence and caesarean rates in each of the TGCS groups.

Results

Of 31 countries, 18 were able to provide data on the TGCS groups, with UK data available only from Northern Ireland. Caesarean birth rates ranged from 16.1 to 56.9%. Countries providing TGCS data had lower caesarean rates than countries without data (25.8% versus 32.9%, P = 0.04). Countries with higher caesarean rates tended to have higher rates in all TGCS groups. Substantial heterogeneity was observed, however, especially for groups 5 (previous caesarean section), 6, 7 (nulliparous/multiparous breech) and 10 (singleton cephalic preterm). The differences in percentages of abnormal lies, group 9, illustrate potential misclassification arising from unstandardised definitions.

Conclusions

Although further validation of data quality is needed, using TGCS in Europe provides valuable comparator and baseline data for benchmarking and surveillance. Higher caesarean rates in countries unable to construct the TGCS suggest that effective routine information systems may be an indicator of a country's investment in implementing evidence‐based caesarean policies.

Tweetable abstract

Many European countries can provide Robson's Ten‐Group Classification to improve caesarean rate comparisons.

Many European countries can provide Robson's Ten‐Group Classification to improve caesarean rate comparisons.

Hospital volume and outcome in inguinal hernia repair: analysis of routine data of 133,449 patients

Introduction

Inguinal hernias are repaired using either open or minimally invasive surgical techniques. For both types of surgery it has been demonstrated that a higher annual surgeon volume is associated with a lower risk of recurrence. This present study investigated the volume-outcome implications for recurrence operations, surgical complications, rate of chronic pain requiring treatment, and 30-day mortality based on the hospital volume.

Materials and methods

The data basis used was the routine data collected throughout the Federal Republic of Germany for persons insured by the Local General Sickness Fund “AOK” who had undergone inpatient inguinal hernia repair between 2013 and 2015. Complications were recorded by means of indicators. Hospitals were divided into five groups on the basis of the annual caseload volume: 1–50, 51–75, 76–100, 101–125, and ≥ 126 inguinal hernia repairs per year. The effect of the hospital volume on the indicators was assessed using multiple logistic regression.

Results

133,449 inguinal hernia repairs were included. The incidence for recurrence operations was 0.95%, for surgical complications 4.22%, for chronic pain requiring treatment 2.87%, and for the 30-day mortality 0.28%. Low volume hospitals (1–50 and 51–75 inguinal hernia repairs per year) showed a significantly increased recurrence risk compared to high volume hospitals with ≥ 126 inguinal hernia repairs per year (odds ratio: 1.53 and 1.24). No significant correlations were found for the other results.

Conclusions

The study gives a detailed picture of hospital care for inguinal hernia repair in Germany. Furthermore, it was noted that the risk of hernia recurrence decreases in line with a rising caseload of the treating hospital.

Common Femoral Artery — Uncommon Aneurysms

Background and Aims:

Femoral artery aneurysms are rare. Their natural history, tendency to embolize or rupture are not well known.

Material and Methods:

Data of all patients seen 1996–2002 with femoral artery aneurysms at the Swiss Cardiovascular Center were analysed. Nine patients with 13 aneurysms of the common femoral artery (CFA) were identified. Only true aneurysms with a diameter of at least 2.5 cm were included. All patients were male, mean age 70 years (range: 57–85 years). Four patients had bilateral femoral aneurysms. Risk factors included hypertension (9/9), smoking (7/9). One of the aneurysms was palpable in 5/9. Four patients were asymptomatic, 5 had Fontaine class II claudication. Five patients also had an aortic aneurysm (AAA), one a thoracic aneurysm; and 6/9 popliteal aneurysms. In all patients, diagnosis was confirmed with duplex scan. Angiography was performed preoperatively.

Results:

The aneurysms were operated on electively using aneurysm secclusion and interposition grafting. There were no significant perioperative complications. Median hospital stay was 8 days.

Conclusion:

CFA aneurysms are rare. They are palpable in nearly half of the cases. They rarely cause thrombotic or embolic complications, but are almost always connected to other aneurysms. Patients with CFA aneurysms should be screened with duplex scan. Operative therapy is straightforward, few complications can be expected. Postoperative follow-up with annual duplex scans is suggested.

Soluble and membrane-bound interleukin (IL)-15 Rα/IL-15 complexes mediate proliferation of high-avidity central memory CD8+ T cells for adoptive immunotherapy of cancer and infections

The lack of persistence of infused T cells is a principal limitation of adoptive immunotherapy in man. Interleukin (IL)-15 can sustain memory T cell expansion when presented in complex with IL-15Rα (15Rα/15). We developed a novel in-vitro system for generation of stable 15Rα/15 complexes. Immunologically quantifiable amounts of IL-15 were obtained when both IL-15Rα and IL-15 genes were co-transduced in NIH 3T3 fibroblast-based artificial antigen-presenting cells expressing human leucocyte antigen (HLA) A:0201, β₂ microglobulin, CD80, CD58 and CD54 [A2-artificial antigen presenting cell (AAPC)] and a murine pro-B cell line (Baf-3) (A2-AAPC^15Rα/15 and Baf-3^15Rα/15 ). Transduction of cells with IL-15 alone resulted in only transient expression of IL-15, with minimal amounts of immunologically detectable IL-15. In comparison, cells transduced with IL-15Rα alone (A2-AAPC^Rα ) demonstrated stable expression of IL-15Rα; however, when loaded with soluble IL-15 (sIL-15), these cells sequestered 15Rα/15 intracellularly and also demonstrated minimal amounts of IL-15. Human T cells stimulated in vitro against a viral antigen (CMVpp65) in the presence of 15Rα/15 generated superior yields of high-avidity CMVpp65 epitope-specific T cells [cytomegalovirus-cytotoxic T lymphocytes (CMV-CTLs)] responding to ≤ 10^{- 13} M peptide concentrations, and lysing targets cells at lower effector : target ratios (1 : 10 and 1 : 100), where sIL-15, sIL-2 or sIL-7 CMV-CTLs demonstrated minimal or no activity. Both soluble and surface presented 15Rα/15, but not sIL-15, sustained in-vitro expansion of CD62L⁺ and CCR7⁺ central memory phenotype CMV-CTLs (T_CM ). 15Rα/15 complexes represent a potent adjuvant for augmenting the efficacy of adoptive immunotherapy. Such cell-bound or soluble 15Rα/15 complexes could be developed for use in combination immunotherapy approaches.

Spontaneous Dissection of Common Iliac Artery

Spontaneous dissection of the iliac artery is very rare but known as a complication of highenergy traumatic injuries and has been reported in connection with pregnancy, collagen diseases, and alpha-1-antitrypsin deficiency. The authors report a 42-year-old man with an acute dissection of the common iliac artery during exercise. Groin pain and claudication were the early symptoms. Computerized angiotomography was diagnostic. Operative iliac artery reconstruction was performed. A prerelease control computed tomography examination showed a dissection of the distal aorta and left iliac artery. To their knowledge, the combination of the 2 dissections has not been previously published.

Fetal Monitoring of Patients Diagnosed with Systemic Lupus Erythematosus - A Case Report

We report a case of pathological foetal Doppler velocity, specifically the absence of end diastolic flow in the umbilical artery (AEDV/REDV), suspected diabetic pregnancy and mesangioproliferative glomerulonephritis, at 32 weeks of gestation. The foetal heart rate tracings were evaluated using a computerised cardiotocogram (Oxford Sonicaid system 8002 Chichester, England) 1 for 20-30 min parallel to the routine cardiotocogram. The ultrasound control at 33 weeks of gestation showed oligohydramnion, foetal centralisation and reduced interval foetal growth. Due to small gestational age (SGA) and oligohydramnion, labour was induced at 36 weeks gestation with vaginal prostaglandin and an amniotomy. Due to cephalopelvic disproportion, a Caesarean section was performed. Signs and symptoms of neonatal lupus were not found.

Statistical controversies in clinical research: an initial evaluation of a surrogate end point using a single randomized clinical trial and the Prentice criteria

Surrogate end point research has grown in recent years with the increasing development and usage of biomarkers in clinical research. Surrogacy analysis is derived through randomized clinical trial data and it is carried out at the individual level and at the trial level. A common surrogate analysis at the individual level is the application of the Prentice criteria. An approach for the evaluation of the Prentice criteria is discussed, with a focus on its most difficult component, the determination of whether the treatment effect is captured by the surrogate. An interpretation of this criterion is illustrated using data from a randomized clinical trial in prostate cancer.

[Joint replacement quality index: the perspective of resident physicians]

BACKGROUND AND AIM

Joint replacement is an established therapy for arthrosis. The quality index for joint replacement (knee and hip) should include screening for quality of patient-centred care in hospitals providing replacements, on the basis of administrative data. The quality index summarizes 16 inpatient and posthospital complications (indicators). The aim of the study was to evaluate this quality index from the medical practitioner's viewpoint.

METHODS

Four semistructured focus groups with 11 family physicians and 8 orthopaedic/trauma surgeons were conducted. The discussions were recorded, transcribed and analysed qualitatively according to Mayring.

RESULTS

Infections and the revision of a total joint arthroplasty have been weighted as the most important indicators from the existing quality indicators. Between the participants some differences regarding the relevance of the indicators thrombosis and pulmonary embolism occurred. These indicators were weighted as more important by family physicians than orthopedic/trauma surgeons. For eight of the indicators, imprecision in words/meaning was criticized. In an open-ended second section, 20 new indicators within the areas complications, management and overall sector communication were identified.

CONCLUSION

Major amendments of the quality index for the joint replacement are necessary. The knowledge gained from this study may serve as a basis for this development.

Die Hydrolyse einiger Borsäureester unter Base-Einfluß in nichtwäßrigen Lösungsmitteln / The Hydrolysis of Some Tris(organyloxy)boranes under Alkaline Influence in Non-aqueous Solvents

The hydrolysis of tris(organyloxy)boranes (boric acid esters) in organic solvents in the presence of KOH leading to potassium polyborates (free from water of crystallization) is studied as to the influences of (a) the reaction medium (ethanol or ligroine/ethanol), (b) the concentration of water, (c) the organyl group of the boric acid ester (methyl, isopropyl, or phenyl), (d) the time of stay of the precipitated insoluble polyborates under the mother liquor (15 to 61850 s), and (e) the temperature during precipitation and the time of stay (—18 to + 60°C).

In the first stage of the reaction, during precipitation time, ester hydrolysis is followed by condensation, while aggregation and desorption processes occur between the time of precipitation and filtration.

Röntgenographische Strukturuntersuchung von Cäsiumhexaoxo-tetrahydroxo-pentaborat-2-dimethylsulfoxid / X-ray Study of the Structure of Cesiumhexaoxo-tetrahydroxo-pentaborate-2-dimethyl Sulfoxide

The compound Cs[B5O6(OH)4] · 2 DMSO was prepared by hydrolysis of tris(methoxy)-borane in organic solvents with small amounts of water in presence of cesium tert-butylate and recrystallized in DMSO (dimethyl sulfoxide). Cs[B5O6(OH)4] · 2 DMSO crystallizes in the monoclinic space group Ρ21/a with a= 9.593(2), b=19.179(4), c= 11.585(2) A, β= 119.99(2)° and Ζ = 4. The crystal structure was determined by single-crystal diffractometer data and refined to a conventional R value of 9.9%. The crystal structure consists of chains of pentaborate anions [B5O6(OH)4]- linked by hydrogen bonds. The cesium cation and the DMSO molecules join the chains to sheets by coordination and hydrogen bonds respectively.

Adeno-associated virus type 6 is retrogradely transported in the non-human primate brain

We recently demonstrated that axonal transport of adeno-associated virus (AAV) is serotype-dependent. Thus, AAV2 is anterogradely transported (e.g., from cell bodies to nerve terminals) in both rat and non-human primate (NHP) brain. In contrast, AAV6 is retrogradely transported from terminals to neuronal cells bodies in the rat brain. However, the directionality of axonal transport of AAV6 in the NHP brain has not been determined. In this study, two Cynomolgus macaques received an infusion of AAV6 harboring green fluorescent protein (GFP) into the striatum (caudate and putamen) by magnetic resonance (MR)-guided convection-enhanced delivery. One month after infusion, immunohistochemical staining of brain sections revealed a striatal GFP expression that corresponded well with MR signal observed during gene delivery. As shown previously in rats, GFP expression was detected throughout the prefrontal, frontal, and parietal cortex, as well as substantia nigra pars compacta and thalamus, indicating retrograde transport of the vector in NHP. AAV6-GFP preferentially transduced neurons, although a few astrocytes were also transduced. Transduction of non-neuronal cells in the brain was associated with upregulation of the major histocompatibility complex-II (MHC-II) and lymphocytic infiltration as previously observed with AAV1 and AAV9. This contrasts with highly specific neuronal transduction in the rat brain. Retrograde axonal transport of AAV6 from a single striatal infusion permits efficient transduction of cortical neurons in significant tissue volumes that otherwise would difficult to achieve.

Comparison of Evoked Electromyography in Three Muscles of the Hand during Recovery from Non-Depolarising Neuromuscular Blockade

The evoked electromyographic responses to supramaximal train of four stimulation of three muscles, all innervated by the ulnar nerve, were compared during recovery from non-depolarising neuromuscular blockade. The abductor digiti minimi was the most resistant to neuromuscular blockade (P <0.001) and the most repeatable (repeatability coefficient 4.4%) when compared with the adductor pollicis (5.9%) and the first dorsal interosseous (5.8%). The abductor digiti minimi had a bias of 0.1 compared to the adductor pollicis and first dorsal interosseous and its limits of agreement were more acceptable (-0.10 to 0.30) at a train of four ratio of 0.9. The electromyography train of four of the adductor pollicis and first dorsal interosseous at 0.8 is equivalent to an electromyography train of four of 0.9 at abductor digiti minimi.

Challenging narrow distal aorta in abdominal aortic aneurysm--endovascular repair using a reversed flared endoprosthesis

INTRODUCTION

Narrow aortic bifurcations are a challenging issue while treating abdominal aortic aneurysm by endovascular means. Off-the-shelf products are often not suitable and special considerations and custom-made endoprostheses are necessary.

REPORT

Alternatively, some morphologies qualify for a flared tube graft. We report two successful aneurysm exclusions using custom-made (Anaconda, Vascutek/Terumo) step-down diameter grafts in patients with tight distal aortas without the need for pre-interventional endograft adjustments.

DISCUSSION

In these two cases, implantation of a custom-made proximally flared tube endograft in treating a localised abdominal aortic aneurysm with a narrow and calcified bifurcation seems feasible. They represent uncommon, yet challenging, issues worthy of attention.

Evaluation of circulating tumor cell (CTC) enumeration as an efficacy response biomarker of overall survival (OS) in metastatic castration-resistant prostate cancer (mCRPC): Planned final analysis (FA) of COU-AA-301, a randomized, double-blind, placebo-controlled, phase III study of abiraterone acetate (AA) plus low-dose prednisone (P) post docetaxel

LBA4517

Background: A preplanned interim analysis of COU-AA-301 showed that AA, a selective androgen biosynthesis (CYP17) inhibitor, significantly improves OS in mCRPC. This is the first phase III study to prospectively assess CTC as a surrogate biomarker as part of a regulatory qualification process, here using updated OS data. Methods: 1,195 patients (pts) with mCRPC post docetaxel were randomized 2:1 to AA (1 g QD) + P (5 mg BID) (n = 797) or placebo + P (n = 398). CTCs (screening and baseline [BL]; post BL at weeks 4, 8 and 12) were enumerated (cells/7.5 mL) at MSKCC and The ICR using CellSearch and analyzed with other prognostic covariates as dichotomous and continuous variables using updated OS data at 775 events (prior to crossover from placebo to AA). CTC (as part of a biomarker panel - LDH, PSA, Hg, AlkPhos) was examined as a surrogate for OS. Multivariate (Cox model) analyses were conducted. Results: At median follow up (FU) of 20.2 mo, the difference in median OS between the 2 groups improved from 3.9 to 4.6 mo (AA 15.8 mo vs placebo 11.2 mo; HR = 0.74; p < .0001). CTC counts were evaluated in 972 pts at screening and BL, 838 at 4 wks, 783 at 8 wks and 723 pts at 12 wks. High concordance between screening and BL values was observed (r = 0.83). CTC conversion using standard definition for unfavorable (CTC ≥ 5) and favorable (CTC < 5) counts was predictive of OS as early as 4 wks after treatment and its inclusion significantly reduced the treatment effect at all post-treatment time points (HR: from 0.74 to 0.97). A reduced model incorporating CTCs and LDH was developed. Conclusions: The magnitude of the treatment effect of AA on OS increased with longer FU. Using standard definition of CTC conversion, the biomarker panel demonstrated a level of surrogacy for OS by correlating well with survival and in a model-adjusted analysis dramatically attenuating the treatment effect. BL CTCs and CTC conversion, along with LDH, were key predictors of OS. Future trials will further evaluate the CTC-based surrogate developed from COU-AA-301.