The relationship between tumour dosimetry, response, and overall survival in patients with unresectable Neuroendocrine Neoplasms (NEN) treated with 177Lu DOTATATE (LuTate)

Peptide Receptor Radionuclide Therapy (PRRT) delivers targeted radiation to Somatostatin Receptor (SSR) expressing Neuroendocrine Neoplasms (NEN). We sought to assess the predictive and prognostic implications of tumour dosimetry with respect to response by 68 Ga DOTATATE (GaTate) PET/CT molecular imaging tumour volume of SSR (MITVSSR) change and RECIST 1.1, and overall survival (OS).

METHODS

Patients with gastro-entero-pancreatic (GEP) NEN who received LuTate followed by quantitative SPECT/CT (Q-SPECT/CT) the next day (Jul 2010 to Jan 2019) were retrospectively reviewed. Single time-point (STP) lesional dosimetry was performed for each cycle using population-based pharmacokinetic modelling. MITVSSR and RECIST 1.1 were measured at 3-months post PRRT.

RESULTS

Median of 4 PRRT cycles were administered to 90 patients (range 2-5 cycles; mean 27.4 GBq cumulative activity; mean 7.6 GBq per cycle). 68% received at least one cycle with radiosensitising chemotherapy (RSC). RECIST 1.1 partial response was 24%, with 70% stable and 7% progressive disease. Cycle 1 radiation dose in measurable lesions was associated with local response (odds ratio 1.5 per 50 Gy [95% CI: 1.1-2.0], p = 0.002) when adjusted by tumour grade and RSC. Median change in MITVSSR was -63% (interquartile range -84 to -29), with no correlation with radiation dose to the most avid lesion on univariable or multivariant analyses (5.6 per 10 Gy [95% CI: -1.6, 12.8], p = 0.133). OS at 5-years was 68% (95% CI: 56-78%). Neither baseline MITVSSR (hazard ratio 1.1 [95% CI: 1.0, 1.2], p = 0.128) nor change in baseline MITVSSR (hazard ratio 1.0 [95% CI: 1.0, 1.1], p = 0.223) were associated with OS when adjusted by tumour grade and RSC but RSC was (95% CI: 0.2, 0.8, p = 0.012).

CONCLUSION

Radiation dose to tumour during PRRT was predictive of radiologic response but not survival. Survival outcomes may relate to other biological factors. There was no evidence that MITVSSR change was associated with OS, but a larger study is needed.

7-Steps medication reviews: analysis of medicine changes in acute medical wards

Introduction

In Northern Ireland, medication errors cause 20 patient deaths, lead to around 800 non-elective hospital admissions and cost £1.9 million annually.1 The iSIMPATHY (implementing Stimulating Innovation in the Management of Polypharmacy and Adherence Through the Years) project is an EU-funded partnership between Scotland, Ireland and Northern Ireland delivering medication reviews using the 7-Steps medication review tool and asking ‘what matters to you?’ 2 The iSIMPATHY 7-Steps review is a new research study in Northern Ireland.

Aim

To identify medicine changes made by an independent prescribing pharmacist during 7-Steps medication reviews.

Method

Medication reviews were delivered on acute medical wards in the Northern Health and Social Care Trust. No patients were excluded from reviews, however reviews were targeted at patients aged 50 years and older and resident in a care home, approaching the end of their lives, prescribed 10 or more medicines or on high-risk medication. Data on medication changes made during 192 medication reviews was collected and analysed to identify the numbers and types of medicines stopped, started and doses altered. Ethical approval was not required, an approved Data Protection Impact Assessment was in place.

Results

Mean number of medicines per patient pre- and post-review were 12.2 and 12.3 respectively. Medicines were stopped in 49% of patients, dose decreased in 36%, changed to a more appropriate medicine in 15%, dose increased in 15% and new medicines started in 55%. Medicines stopped included opioids and gabapentenoids (18%), nutritional and electrolyte supplements (15%), items for comfort (9%), antidepressants (including amitriptyline for pain) (10%), antihypertensives and diuretics (8%), bladder anticholinergics and mirabegron (5%), laxatives (4%), betahistine (3%), quinine (2%). Dose decreases were made for analgesics including opioids (28%), PPI/H2RA (23%), anticoagulants (13%), statins and fibrates (6%), antihypertensives (6%), benzodiazepines and z-drugs (5%), antidiabetics (3%). Dose increases were made for anticoagulants and items for comfort (both 26%), laxatives (24%), pancreatin (15%), nutritional and electrolyte supplements (9%). Medicines started included nutritional and electrolyte supplements (45%), medicines for comfort (19%), laxatives (15%), nicotine replacement (7%), PPI/H2RA (2%), bisphosphonates (2%).

Discussion/Conclusion

The 7-STEPS medicine reviews led to important medicine changes while the number of medicines following review remained the same. The person-centred, holistic approach facilitated identification and actioning of the medicine changes that mattered to individual patients. Stopped and decreased dose medicines included high risk medicines, those likely to cause adverse effects or high anticholinergic burden and medicines no longer needed or effective for the individual. Medicine doses were increased for high risk medicines, to ensure sufficient nutritional, electrolyte and enzyme replacement and items for comfort for example constipation. Importantly, unmet therapeutic needs were identified and new medicines were prescribed to address these needs, for example, acid suppressants, bisphosphonates, anticoagulants, statins, antidiabetics, nicotine replacement therapy and for patient’s comfort including pain relief. Limitations include results may not be reflective of all hospital patients as set in an acute setting and through the iSIMPATHY project.

References

1. Transforming medication safety in Northern Ireland, Department of Health 2022. Available from: https://www.health-ni.gov.uk/sites/default/files/publications/health/Transforming-medication-safety-in-Northern-Ireland_1.pdf

2. iSimpathy. Making Medication Personal. 2022. Available from: https://www.isimpathy.eu/

Single-nuclei and bulk-tissue gene-expression analysis of pheochromocytoma and paraganglioma links disease subtypes with tumor microenvironment

Pheochromocytomas (PC) and paragangliomas (PG) are rare neuroendocrine tumors associated with autonomic nerves. Here we use single-nuclei RNA-seq and bulk-tissue gene-expression data to characterize the cellular composition of PCPG and normal adrenal tissues, refine tumor gene-expression subtypes and make clinical and genotypic associations. We confirm seven PCPG gene-expression subtypes with significant genotype and clinical associations. Tumors with mutations in VHL, SDH-encoding genes (SDHx) or MAML3-fusions are characterized by hypoxia-inducible factor signaling and neoangiogenesis. PCPG have few infiltrating lymphocytes but abundant macrophages. While neoplastic cells transcriptionally resemble mature chromaffin cells, early chromaffin and neuroblast markers are also features of some PCPG subtypes. The gene-expression profile of metastatic SDHx-related PCPG indicates these tumors have elevated cellular proliferation and a lower number of non-neoplastic Schwann-cell-like cells, while GPR139 is a potential theranostic target. Our findings therefore clarify the diverse transcriptional programs and cellular composition of PCPG and identify biomarkers of potential clinical significance.

FDG PET/CT imaging in detecting and guiding management of invasive fungal infections: a retrospective comparison to conventional CT imaging

PURPOSE

Invasive fungal infections (IFIs) are common in immunocompromised patients. While early diagnosis can reduce otherwise high morbidity and mortality, conventional CT has suboptimal sensitivity and specificity. Small studies have suggested that the use of FDG PET/CT may improve the ability to detect IFI. The objective of this study was to describe the proven and probable IFIs detected on FDG PET/CT at our centre and compare the performance with that of CT for localization of infection, dissemination and response to therapy.

METHODS

FDG PET/CT reports for adults investigated at Peter MacCallum Cancer Centre were searched using keywords suggestive of fungal infection. Chart review was performed to describe the risk factors, type and location of IFIs, indication for FDG PET/CT, and comparison with CT for the detection of infection, and its dissemination and response to treatment.

RESULTS

Between 2007 and 2017, 45 patients had 48 proven/probable IFIs diagnosed prior to or following FDG PET/CT. Overall 96% had a known malignancy with 78% being haematological. FDG PET/CT located clinically occult infection or dissemination to another organ in 40% and 38% of IFI patients, respectively. Of 40 patients who had both FDG PET/CT and CT, sites of IFI dissemination were detected in 35% and 5%, respectively (p < 0.001). Of 18 patents who had both FDG PET/CT and CT follow-up imaging, there were discordant findings between the two imaging modalities in 11 (61%), in whom normalization of FDG avidity of a lesion suggested resolution of active infection despite a residual lesion on CT.

CONCLUSION

FDG PET/CT was able to localize clinically occult infection and dissemination and was particularly helpful in demonstrating response to antifungal therapy.

TERT structural rearrangements in metastatic pheochromocytomas

Pheochromocytomas (PC) and paragangliomas (PGL) are endocrine tumors for which the genetic and clinicopathological features of metastatic progression remain incompletely understood. As a result, the risk of metastasis from a primary tumor cannot be predicted. Early diagnosis of individuals at high risk of developing metastases is clinically important and the identification of new biomarkers that are predictive of metastatic potential is of high value. Activation of TERT has been associated with a number of malignant tumors, including PC/PGL. However, the mechanism of TERT activation in the majority of PC/PGL remains unclear. As TERT promoter mutations occur rarely in PC/PGL, we hypothesized that other mechanisms - such as structural variations - may underlie TERT activation in these tumors. From 35 PC and four PGL, we identified three primary PCs that developed metastases with elevated TERT expression, each of which lacked TERT promoter mutations and promoter DNA methylation. Using whole genome sequencing, we identified somatic structural alterations proximal to the TERT locus in two of these tumors. In both tumors, the genomic rearrangements led to the positioning of super-enhancers proximal to the TERT promoter, that are likely responsible for the activation of the normally tightly repressed TERT expression in chromaffin cells.

Cousins not twins: intratumoural and intertumoural heterogeneity in syndromic neuroendocrine tumours

Hereditary endocrine neoplasias, including phaeochromocytoma/paraganglioma and medullary thyroid cancer, are caused by autosomal dominant mutations in several familial cancer genes. A common feature of these diseases is the presentation of multiple primary tumours, or multifocal disease representing independent tumour clones that have arisen from the same initiating genetic lesion, but have undergone independent clonal evolution. Such tumours provide an opportunity to discover common cooperative changes required for tumourigenesis, while controlling for the genetic background of the individual. We performed genomic analysis of synchronous and metachronous tumours from five patients bearing germline mutations in the genes SDHB, RET, and MAX. Using whole exome sequencing and high-density single-nucleotide polymorphism arrays, we analysed two to four primary tumours from each patient. We also applied multi-region sampling, to assess intratumoural heterogeneity and clonal evolution, in two cases involving paraganglioma and medullary thyroid cancer, respectively. Heterogeneous patterns of genomic change existed between synchronous or metachronous tumours, with evidence of branching evolution. We observed striking examples of evolutionary convergence involving the same rare somatic copy-number events in synchronous primary phaeochromocytoma/paraganglioma. Convergent events also occurred during clonal evolution of metastatic medullary thyroid cancer. These observations suggest that genetic or epigenetic changes acquired early within precursor cells, or pre-existing within the genetic background of the individual, create contingencies that determine the evolutionary trajectory of the tumour. Copyright © 2017 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Pheo-Type: A Diagnostic Gene-expression Assay for the Classification of Pheochromocytoma and Paraganglioma

CONTEXT

Pheochromocytomas and paragangliomas (PPGLs) are heritable neoplasms that can be classified into gene-expression subtypes corresponding to their underlying specific genetic drivers.

OBJECTIVE

This study aimed to develop a diagnostic and research tool (Pheo-type) capable of classifying PPGL tumors into gene-expression subtypes that could be used to guide and interpret genetic testing, determine surveillance programs, and aid in elucidation of PPGL biology.

DESIGN

A compendium of published microarray data representing 205 PPGL tumors was used for the selection of subtype-specific genes that were then translated to the Nanostring gene-expression platform. A support vector machine was trained on the microarray dataset and then tested on an independent Nanostring dataset representing 38 familial and sporadic cases of PPGL of known genotype (RET, NF1, TMEM127, MAX, HRAS, VHL, and SDHx). Different classifier models involving between three and six subtypes were compared for their discrimination potential.

RESULTS

A gene set of 46 genes and six endogenous controls was selected representing six known PPGL subtypes; RTK1-3 (RET, NF1, TMEM127, and HRAS), MAX-like, VHL, and SDHx. Of 38 test cases, 34 (90%) were correctly predicted to six subtypes based on the known genotype to gene-expression subtype association. Removal of the RTK2 subtype from training, characterized by an admixture of tumor and normal adrenal cortex, improved the classification accuracy (35/38). Consolidation of RTK and pseudohypoxic PPGL subtypes to four- and then three-class architectures improved the classification accuracy for clinical application.

CONCLUSIONS

The Pheo-type gene-expression assay is a reliable method for predicting PPGL genotype using routine diagnostic tumor samples.

Abstract 3875: Merkel cell carcinomas in Australia have distinct mutation profiles reflecting viral etiology and UV-related DNA damage

Background/Aims: Merkel cell carcinoma (MCC) is rare but aggressive cutaneous high-grade neuroendocrine cancer. Viral infection and sun-exposure are known risk factors for development of MCC, the latter being important in Australia, which has the highest reported incidence of MCC worldwide. There is growing evidence to suggest that MCC associated with the Merkel cell polyoma virus (MCPyV) is clinically, biologically and genetically distinct to those tumors without viral infection. We aimed to assess mutations arising in MCC in the Australian population by targeted massively-parallel sequencing (MPS) to gain new biological insight and identify novel therapeutic opportunities in this disease.

Methods: MCPyV was detected in tumours by PCR amplification of large-T antigen coding DNA. The tumor cohort was comprised of seven MCPyV-positive and 16 MCPyV-negative tumors reflecting the reported prevalence of these subtypes in the Australian population. We also sequenced two viral negative MCC cell lines. Hybridization-based DNA capture was used for enrichment of 625 cancer genes for high-depth MPS of tumor and the matching germline DNA, where available. Single nucleotide variants and small insertions and deletions were detected using GATK and muTect variant calling tools and annotated using ENSEMBL variant effect predictor. Somatic variants were enriched in the data by filtering out any variants found in matching germline samples or population-based polymorphism databases

Results: High mutation burden was found exclusively in the MCPyV-negative cases with the hallmark signature of UV induced DNA damage. Somatic mutations were identified in known cancer genes specific to the MCPyV-negative tumors. Deleterious RB1 and TP53 mutations were found in 17 and 16 of the MCPyV-negative cases, respectively. Canonical mutations were identified in PIK3CA, HRAS as well as truncating NF1 mutations, indicating that activation of the PI3K and RAS-MAPK pathways are important for pathogenesis of MCPyV-negative tumors. Treatment of two cell lines harboring either PIK3CA or HRAS mutations, respectively, showed in vitro sensitivity to the dual PI3K/mTOR inhibitor PF-04691502.

Conclusions: The identification of a UV-induced DNA damage signature and mutations in PI3K and MAPK pathways specific to viral negative tumors confirms the distinct routes to pathogenesis in this disease subtype. This study provides new insight into the biology of viral negative MCC and potential opportunities for the deployment of targeted therapies in this patient group.

Citation Format: Stephen Q. Wong, Kelly Waldeck, Ismael A. Vergara, Jason Li, Richard Lupat, Timothy Semple, Carleen Cullinane, Gisela Mir Arnau, Meredith Johnston, Annette Hogg, Anthony T. Papenfuss, Stephen Fox, Grant McArthur, Anthony Gill, Rodney J. Hicks, Richard W. Tothill. Merkel cell carcinomas in Australia have distinct mutation profiles reflecting viral etiology and UV-related DNA damage. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3875. doi:10.1158/1538-7445.AM2015-3875

An automated voxelized dosimetry tool for radionuclide therapy based on serial quantitative SPECT/CT imaging

PURPOSE

To create an accurate map of the distribution of radiation dose deposition in healthy and target tissues during radionuclide therapy.

METHODS

Serial quantitative SPECT∕CT images were acquired at 4, 24, and 72 h for 28 (177)Lu-octreotate peptide receptor radionuclide therapy (PRRT) administrations in 17 patients with advanced neuroendocrine tumors. Deformable image registration was combined with an in-house programming algorithm to interpolate pharmacokinetic uptake and clearance at a voxel level. The resultant cumulated activity image series are comprised of values representing the total number of decays within each voxel's volume. For PRRT, cumulated activity was translated to absorbed dose based on Monte Carlo-determined voxel S-values at a combination of long and short ranges. These dosimetric image sets were compared for mean radiation absorbed dose to at-risk organs using a conventional MIRD protocol (OLINDA 1.1).

RESULTS

Absorbed dose values to solid organs (liver, kidneys, and spleen) were within 10% using both techniques. Dose estimates to marrow were greater using the voxelized protocol, attributed to the software incorporating crossfire effect from nearby tumor volumes.

CONCLUSIONS

The technique presented offers an efficient, automated tool for PRRT dosimetry based on serial post-therapy imaging. Following retrospective analysis, this method of high-resolution dosimetry may allow physicians to prescribe activity based on required dose to tumor volume or radiation limits to healthy tissue in individual patients.

Effect of PET/CT on management of patients with non-small cell lung cancer: results of a prospective study with 5-year survival data

We investigated the incremental management impact and prognostic value of staging with (18)F-FDG PET/CT in patients with non-small cell lung cancer (NSCLC) being considered for potentially curative therapies.

METHODS

Information on 168 consecutive patients with NSCLC being considered for surgery or definitive radiotherapy with curative intent before PET/CT was entered into a prospective database. The pre-PET/CT management plan, based on conventional imaging (conventional CT, appropriately supplemented by bone scintigraphy or other modalities), was defined prospectively by referring clinicians before PET/CT results became available. After PET/CT, actual clinical management was recorded, and patients were followed up until 5 y or death. The appropriateness of PET/CT management plans was assessed by biopsy when available, clinical follow-up, and survival analysis.

RESULTS

Stage was discordant on PET/CT and conventional imaging in 50.6% of patients (41.1% upstaged, 9.5% downstaged), with high management impact (change in treatment modality or curative intent) in 42.3% of patients. Both conventional imaging stage and PET/CT stage were strongly predictive of overall survival (OS) but there were greater differences between hazard rates and separations in the OS curves for stage groupings determined using PET/CT. OS was also strongly predicted by PET/CT-directed choice of therapy (P < 0.0001).

CONCLUSION

PET/CT frequently affects patient management and strongly predicts OS in NSCLC, supporting the appropriateness of such changes.

Femoral torsion in patients with Blount’s disease

In 1937 Blount described a series of 28 patients with ‘Tibia vara’. Since then, a number of deformities in the tibia and the femur have been described in association with this condition.

We analysed 14 children with Blount’s disease who were entered into a cross-sectional study. Their mean age was 10 (2 to 18). They underwent a clinical assessment of the rotational profile of their legs and a CT assessment of the angle of anteversion of their hips (femoral version). We compared our results to previously published controls. A statistically significant increase in femoral anteversion was noted in the affected legs, with on average the femurs in patients with Blount’s disease being 26° more anteverted than those in previously published controls.

We believe this to be a previously unrecognised component of Blount’s disease, and that the marked intoeing seen in the disease may be partly caused by internal femoral version, in addition to the well-recognised internal tibial version.

Early therapeutic response assessment by18FDG-positron emission tomography during chemotherapy in patients with diffuse large B-cell lymphoma: Isolated residual positivity involving bone is not usually a predictor of subsequent treatment failure

Residual 2-fluoro-2-deoxyglucose (FDG) - positron emission tomography (PET) positivity during treatment of patients with diffuse large B-cell lymphoma (DLBLC) prospectively identifies a subgroup at high likelihood of subsequent treatment failure. A single institution clinical audit of FDG-PET performance for this indication was undertaken for patients with DLBCL treated with anthracycline-based chemotherapy +/- radiotherapy. Of 45 eligible patients, 14 (31%) were PET-positive after a median of three chemotherapy cycles (range 1 - 5), of which 10 (71%) progressed at a median of 6.5 months. An interim positive PET was a statistically significant adverse prognostic factor for treatment failure (P < 0.0001, log-rank analysis) with a hazard ratio for a positive interim-treatment PET of 9 (95% confidence interval = 4 - 55) and positive predictive value of 71% and negative predictive value of 90%. Notably, four patients with low-grade FDG-avidity limited to sites previously involved by biopsy-proven osseous lymphoma, remain progression-free (median follow-up 62 months). Low-grade FDG-avidity on interim restaging at sites of bone involvement by DLBCL at diagnosis, appears to be less predictive of disease progression than residual nodal or extra-nodal soft tissue abnormality by PET.

Usefulness of fluorine-18 fluorodeoxyglucose positron emission tomography in patients with a residual structural abnormality after definitive treatment for squamous cell carcinoma of the head and neck

BACKGROUND

Residual structural abnormalities after definitive treatment of head and neck squamous cell carcinoma (HNSCC) are common and pose difficult management problems. The usefulness of fluorine-18 fluorodeoxyglucose positron emission tomography (FDG PET) to supplement conventional evaluation with clinical and standard radiologic examination (CE) in such patients was assessed.

METHODS

Fifty-three eligible patients were identified with residual structural abnormalities on CE. True disease extent could be validated in 46 patients. Patients had a median potential follow-up of 55 months (range, 41-75 months) from the date of PET scan to the analysis closeout date.

RESULTS

PET had better diagnostic accuracy than CE (p = .0002) and induced management change in 21 patients (40%; 95% confidence interval [CI], 26%-54%), including avoidance of unnecessary planned surgery in 14 patients with negative PET. Appropriate management change was confirmed in 19 (95%) of 20 evaluable cases. Disease presence and extent assessment by PET were significant predictors of survival (p < .0001), whereas the extent of disease determined by CE was not.

CONCLUSION

PET added significantly to the value of CE in restaging disease in patients with structural abnormalities after definitive treatment of HNSCC. Management decisions based on PET were appropriate in most patients.

Clinical impact of, and prognostic stratification by, F-18 FDG PET/CT in head and neck mucosal squamous cell carcinoma

BACKGROUND

The aim of this study was to determine prospectively the incremental value of positron emission tomography/computed tomography (PET/CT) over conventional assessment (clinical examination and CT/MRI imaging).

METHODS

All patients undergoing (18)F-fluorodeoxyglucose (FDG)-PET/CT for primary head and neck mucosal squamous cell carcinoma between January 2002 and December 2003 (inclusive) were included in this study provided they had undergone contemporaneous conventional assessment of the head and neck region and had 12 months minimum follow-up.

RESULTS

Seventy-six patients underwent 100 PET/CT scans. The majority of patients (74%) were treated with definitive (chemo)radiotherapy. Median follow-up time was 28 months. PET/CT led to a TNM classification alteration in 34% (12/35), a change in radiotherapy planning technique and/or dose in 29% (10/35), and altered treatment response assessment in 43% (13/30). A complete metabolic response was predictive of overall survival (p = .037).

CONCLUSION

Our results support incorporation of PET/CT into the management paradigm of head and neck mucosal squamous cell carcinoma.

Utility of 18-fluorodeoxyglucose positron emission tomography (FDG-PET) in the staging, radiotherapy planning and prognostication of anal cancer

4559

Background: Accurate inguinal and pelvic nodal staging in anal cancer is important for prognosis and planning of (chemo)radiation fields. There is strong evidence for the impact of FDG-PET in staging and management of cancer, with early reports of an increasing role in outcome prognostication for a number of tumours. We aimed to determine the impact of FDG-PET on the nodal staging, radiotherapy planning and prognostication of patients with primary anal cancer. Methods: Sixty-two consecutive patients with anal cancer referred to a single tertiary oncology centre between August 1997 and November 2005 were staged with conventional imaging (CIm), computed tomography, magnetic resonance imaging and chest x-ray and by FDG-PET. The stage determined by CIm and the proposed management plan was prospectively recorded and changes in stage and management as a result of FDG-PET assessed. Patients were treated using uniform radiotherapy technique and dose. The accuracy of changes and prognostication of FDG-PET was validated by subsequent clinical follow-up. Kaplan-Meier survival analysis was used to assess survival for the cohort and by FDG-PET and CIm stage. Results: The TNM stage group was changed in 23% (14/62) as a result of FDG-PET (15% up-staged, 8% down-staged). Fourteen percent of T1 patients (3/22), 42% of T2 patients (10/24) and 38% of T3–4 patients (6/16), assessed using CIm, had a change in their N or M stage following FDG-PET. Sensitivity for nodal disease by FDG-PET and CIm was 92% and 72% respectively. The staging FDG-PET scan altered management intent in 3% (2/62), and altered radiotherapy fields in 13% (8/62). Estimated 5 year overall survival and progression free survival (PFS) for the cohort was 77.3% (95% CI 55.3%-90.4%) and 72.2% (95% CI 51.5%-86.4%) respectively. Estimated 5 year PFS for FDG-PET and CIm staged N2–3 disease was 70% (95% CI 42.8%-87.9%) and 55.3% (95% CI 23.3%-83.4%) respectively. Conclusions: FDG-PET shows increased sensitivity over CIm for staging nodal disease in anal cancer and changes treatment intent or radiotherapy fields in a significant proportion of patients. Improved 5 year PFS for FDG-PET staged N2–3 disease could be consistent with more accurate nodal staging and radiotherapy targeting.

No significant financial relationships to disclose.

Positron-emission tomography reveals early flare in uptake of FLT in tumors following chemotherapy with gemcitabine

2537

Background: Strategies to monitor molecular & cellular responses to novel cell cycle targeting agents are vital to provide proof of their mechanism & biological activity. In developing biomarkers for the novel chk1 inhibitor, PF-477736, we demonstrated that gemcitabine chemotherapy induced a significant increase, or flare, in uptake of the PET tracer, 3’-deoxy-3’flurothymidine (FLT), into tumor xenografts 24 h after dosing (Proc ASCO 24:A3045, 2006). We postulated that an early flare in FLT may also occur following gemcitabine therapy in human tumors. Methods: Eligible patients had at least 1 malignant lesion identified by CT scan outside of a previous radiation field. Patients received a baseline FLT-PET scan day-1 to -4 relative to 1st dose of gemcitabine at 1,000 mg/m2, and a post dose FLT- PET scan 22–26 h after gemcitabine. Endpoints were FLT uptake as assessed by: SUV; a qualitative scoring system; and tumor-to-background (T:B) ratios using liver, mediastinum and bone marrow as references. Results: Six of 8 planned patients with 14 index lesions have been accrued in this pilot study. 4/6 patients demonstrated increased uptake of FLT as defined by >50% increase in SUV or T:B ratio in at least 1 lesion. Analysing all index lesions showed an increase in FLT-uptake post gemcitabine as assessed by a 4 point qualitative scoring system from 1.6±0.2 to 2.7±0.1 (p=0.01) or T:B 1.1±0.2 to 2.0±0.3 (p<0.01) using liver as a reference. Interestingly in contrast to increased uptake in tumors, uptake of FLT in bone marrow was reduced from an SUV of 6.4±0.6 to 3.4±0.7 (p<0.01) following gemcitabine. Conclusion: Following treatment with gemcitabine there was an early flare in uptake of FLT into many tumors. In contrast, uptake in bone marrow was reduced. FLT-PET appears to be a promising tool to monitor the cell cycle response of both tumor and bone marrow to cytotoxic chemotherapy.

No significant financial relationships to disclose.

[Clinical application of (18)F-FDG PET/CT to staging and treatment effectiveness monitoring of nasopharyngeal carcinoma]

BACKGROUND & OBJECTIVE

Fluorine-18 fluorodeoxyglucose ((18)F-FDG) PET/CT could increase the accuracy of diagnosis, staging, and treatment effectiveness monitoring of many malignant diseases, such as lung cancer and esophageal cancer. This study was to evaluate the clinical application of (18)F-FDG PET/CT to the staging, restaging, and treatment effectiveness monitoring of nasopharyngeal carcinoma (NPC).

METHODS

The reports of whole body (18)F-FDG PET/CT scans, performed from Feb. 2002 to Dec. 2005 on 43 NPC patients (26 men and 17 women with median age of 52 years) in Peter MacCallum Cancer Center, were reviewed. The final diagnoses were made according to medical records, pathologic reports and follow-up information. The accuracy, specificity, sensitivity, positive predictive value (PPV), and negative predictive value (NPV) of (18)F-FDG PET/CT, CT and MRI were calculated and analyzed.

RESULTS

The accuracy, specificity, sensitivity, PPV, and NPV of (18)F-FDG PET/CT were 95.3%, 100.0%, 85.7%, 93.8%, and 100.0%, respectively; those of CT and MRI were 65.5%, 79.4%, 64.7%, 81.8%, and 57.9%, respectively. The results of (18)F-FDG PET/CT led to changes in the medical management of 2 staged patients, and 7 restaged patients and 5 patients in monitoring group. (18)F-FDG PET/CT scan affected the therapy plan of 3 restaged patients and 11 patients in monitoring group. Two cases of second primary malignancies(1 case of thyroid carcinoma and 1 case of low grade gastric carcinoma) were detected by (18)F-FDG PET/CT scan.

CONCLUSION

(18)F-FDG PET/CT is better than conventional imaging in N and M staging and treatment effectiveness monitoring of NPC.

How do oncologists deal with incidental abnormalities on whole-body fluorine-18 fluorodeoxyglucose PET/CT?

BACKGROUND

Combined positron emission tomography (PET)/computed tomography (CT) using fluorine-18 fluorodeoxyglucose (FDG) is an exciting technique for cancer evaluation, but false-positive results are a recognized limitation. The aim of the study was to evaluate how oncologists deal with focal extrathyroidal FDG abnormalities considered by imaging specialists to be unrelated to the referral indication.

METHODS

PET scan reports from a 12-month period from August 2002 to July 2003 in 1727 consecutive patients (mean age, 63 years) were reviewed. Incidental, nonphysiologic FDG abnormalities were classified based on the report conclusion. The frequency with which such abnormalities were investigated by oncologists and the final diagnosis were compared with the imaging diagnosis with a minimum potential follow-up of 2 years (mean, 27.5 months).

RESULTS

Incidental FDG abnormalities were reported in 199 (12%) of 1727 patients, including 181 with adequate follow-up. Of 59 cases with a suspected second malignancy, 34 (58%) were actively investigated, with 14 confirmed, 7 unexpected metastatic sites, and 10 other active pathologies. Only 1 further cancer was subsequently detected in the 25 (42%) patients not actively investigated. Conversely, of 122 sites presumed to be benign, only 10 (8%) were actively investigated. Only 2 were proven to relate to malignancy.

CONCLUSIONS

Although incidental abnormalities were common, most were benign and appropriately categorized by experienced readers. For actively investigated extrathyroidal abnormalities, a neoplastic basis was confirmed in over 60% of cases. Conversely, for cases deemed most likely benign by the PET/CT report or after review of readily available clinical information by the referring oncologist, the rate of malignancy was less than 2%.

Powerful prognostic stratification by [18F]fluorodeoxyglucose positron emission tomography in patients with metastatic breast cancer treated with high-dose chemotherapy

PURPOSE

This study examines the use of [(18)F]fluorodeoxyglucose positron emission tomography (FDG-PET) for the evaluation of the therapeutic response for patients treated with high-dose chemotherapy (HDC) with autologous stem cell transplantation for metastatic breast cancer (MBC) focusing on prognostic stratification.

PATIENTS AND METHODS

Forty-seven patients with MBC were treated with a maximum of three cycles of HDC. Therapeutic response was assessed with conventional imaging (CImg; including a computed tomography in all cases and ultrasound, mammography, and bone scanning as clinically indicated) and by FDG-PET study performed after the last cycle of HDC. Parameters analyzed for predicting survival were FDG-PET and CImg results, pattern of disease, prior treatment, and HDC regimen.

RESULTS

Complete responses were observed in 16 patients (37%) with CImg and 34 patients (72%) with FDG-PET. The FDG-PET result was the most powerful and independent predictor of survival; patients with a negative post-treatment FDG-PET had a longer median survival than patients with a positive FDG-PET (24 months v 10 months; P < .001). By multivariate analysis the relative risk (RR) of death was higher in patients with FDG-PET-positive disease (RR, 5.3), prior anthracycline treatment (RR, 3.3), or with visceral metastasis (RR, 2.4).

CONCLUSION

A single FDG-PET study performed after completion of HDC for MBC can powerfully stratify for survival. This may have implications for how we should assess outcome after conventional-dose therapy for MBC and warrants additional study.

Early FDG-PET imaging after radical radiotherapy for non-small-cell lung cancer: inflammatory changes in normal tissues correlate with tumor response and do not confound therapeutic response evaluation

PURPOSE

To investigate the relationship between positron emission tomography (PET) detected inflammatory changes in irradiated normal tissues and metabolic response at tumor sites in patients receiving radical radiotherapy for non-small-cell lung cancer. The prognostic significance of these changes was also studied.

METHODS

In 73 consecutive patients, (18)F-fluorodeoxyglucose (FDG) PET was performed at a median of 70 days after completion of radical radiotherapy. Radiation-induced inflammatory change was scored for normal tissues within the radiation treatment volume using a 0-3 grading scale. Metabolic tumor response was assessed using a pattern-recognition algorithm comparing pre- and posttreatment scans. Prognostic significance of inflammatory changes was tested using the Cox proportional hazards regression model.

RESULTS

Increased FDG uptake in normal tissues (radiotoxicity) was associated with a greater likelihood of complete or partial tumor response on both PET (p = 0.0044) and computed tomography (p = 0.029). Prognostic stratification provided by PET response was both significant and of a similar magnitude in patients with low- and high-grade radiotoxicity.

CONCLUSION

Postradiotherapy inflammatory changes detected by FDG-PET are positively correlated with tumor response, suggesting that tumor radioresponsiveness and normal tissue radiosensitivity may be linked. Prognostic stratification provided by PET is not compromised by inflammatory changes if a meticulous visual response assessment technique is used.

Investigations with FDG-PET scanning in prostate cancer show limited value for clinical practice

The aim of this study was to investigate FDG-PET (fluorodeoxyglucose positron emission tomography) imaging in the management of prostate cancer. Twenty-two patients were studied during different disease phases of prostate cancer, for staging or restaging to clarify specific clinical questions. FDG-PET was performed encompassing the thorax, abdomen and pelvis using the Penn PET 300H scanner. Scanning was begun 60 min after 18F fluorodeoxyglucose marker. Patients were catheterized and administered diuretics to minimize urinary activity. Information obtained with FDG-PET was concordant with findings from other investigations in 7/22 (32%) patients, discordant in 15/22 (68%) patients and equivalent in one patient (4%). PET indicated progressive disease in five patients with prostate-specific antigen (PSA) < 4 ng/L. The impact on management of the patients was high in 46% of cases, low in 41% and for 14% there was no impact on management. The accuracy of FDG-PET was 72% (95% CI 50-89) as confirmed by invasive diagnostics/follow-up. FDG-PET can provide useful information and improve the clinician's decision on further management procedures in selected patients with low PSA and bone or lymph node changes. A negative PET scan in prostate cancer should be interpreted with caution.

Agreement between general practice prescription data and self-reported use of hormone replacement therapy and treatment for various illnesses

BACKGROUND

Epidemiological studies of the effects of hormone replacement therapy (HRT) often rely on exposure data and information on past health from self-administered questionnaires. The accuracy with which women report current use of HRT and the specific preparation in use is not known. This study aims to compare aspects of self-reported use of HRT and treatment for various conditions with data from general practice prescription records.

METHODS

Reported questionnaire data on use of HRT were compared with those on the general practice prescription record for 570 women participating in the Million Women Study from two general practices in the UK.

RESULTS

There was excellent agreement between data from the self-administered questionnaire and the prescription record: 96% agreement (kappa = 0.91) for current use of HRT, 95% agreement (kappa = 0.90) for any use of HRT during the period covered by the prescription record, and 97% agreement (kappa = 0.95) among current users for whether the HRT preparation contained oestrogen alone, combined oestrogen/progestogen, or some other constituents. Among former HRT users who provided questionnaire information on the preparation they used most recently, there was 69% agreement on the proprietary preparation used and 97% agreement (kappa = 0.93) on the hormonal constituents used. Agreement between reported treatment for various conditions and the presence of a prescription appropriate for that condition ranged from 89-99% (kappa 0.53-0.92), and was highest for thyroid disease and asthma.

CONCLUSION

Important aspects of use of HRT, such as type of preparation currently being used, are reported very reliably by women completing a self-administered questionnaire.

Evaluation of high-risk melanoma: comparison of [18F]FDG PET and high-dose 67Ga SPET

Recently the potential of whole-body positron emission tomography scanning using 18F-fluorodeoxyglucose (FDG PET) has led to renewed interest in the use of functional imaging for the detection of occult metastatic melanoma. This study compared dedicated FDG PET with high-dose gallium-67 imaging incorporating whole-body scanning and comprehensive single-photon emission tomography (SPET) in 122 cases (121 patients) in which the two scans were performed <6 weeks apart. All patients were at high clinical risk of occult metastatic disease and 49 (40%) had abnormality suggestive of metastatic disease by at least one functional imaging technique. Discrepant scan findings were followed up to determine which technique more accurately reflected disease status. There were 23/122 (19%; 95% CI: 12%-26%) cases with discordant scan results in respect of either the presence of melanoma (11 cases) or the extent of disease (12 cases). PET correctly identified more disease than 67Ga SPET in 14 cases (including three incidental primary tumours) and was true negative in three further patients with abnormal 67Ga SPET. There were six patients with true positive 67Ga SPET in whom FDG PET was false negative (one small cutaneous deposit, one residual axillary node rated equivocal on FDG PET due to postoperative changes, one adrenal metastasis inseparable from renal activity on FDG PET and three cases in which sites missed on FDG PET were seen on 67Ga SPET. Thus, FDG PET provided incremental diagnostic information compared with 67Ga SPET in 17/23 patients, while 67Ga SPET provided incremental information compared with PET in 6/23 cases ( P=0.035). Based on Australian Medicare reimbursement levels, the net cost per patient with clinical management benefit of replacing 67Ga SPET with FDG PET was estimated to be less than EUR 1,750. These results suggest that FDG PET provides incremental and clinically important information in around 10% of patients at a low incremental cost which, combined with greater patient convenience and lower radiation dosimetry, make FDG PET the functional imaging technique of choice for evaluation of suspected metastatic melanoma.

The clinical impact of (18)F-FDG PET in patients with suspected or confirmed recurrence of colorectal cancer: a prospective study

This prospective study aimed to confirm, in a clinical setting, the benefits suggested by earlier retrospective studies of (18)F-FDG PET scanning for the evaluation of patients with suspected recurrence of colorectal cancer.

METHODS

The referring oncologist was asked to prospectively assign a treatment plan for 102 consecutive patients being evaluated by (18)F-FDG PET for suspected or confirmed recurrence of colorectal cancer and without evidence of unresectable disease on conventional staging investigations, including CT. This treatment plan was then compared with that based on incremental information supplied by PET. Management changes were validated by follow-up.

RESULTS

For 6 patients, the oncologist would not commit to a management plan without access to PET information, and for all these patients, PET correctly guided management. Of the remaining 96 patients, the management plan for 54 (56%) was altered as a direct result of unexpected PET findings. Thus, PET directly influenced management in 60 (59%) of 102 patients. The discrepant PET results could be validated in 57 patients and were correct for both the presence and the extent of malignant disease in 52 (91%) of these patients but were false-positive in 1 patient because of a pelvic abscess and underestimated the extent of metastatic disease in 4 (7%). Relapse was confirmed in 49 (98%) of 50 evaluable patients with positive PET findings. Significantly, planned surgery was abandoned in 26 (60%) of 43 patients because of incremental PET findings. Of the 42 patients for whom management was not changed by PET findings, false-negative PET findings were documented for 5 (4 with metastases < 1 cm), and the PET findings for 1 were presumed to be false-positive because of sarcoidosis.

CONCLUSION

This prospective study confirms the high impact, suggested by previous retrospective analyses, of (18)F-FDG PET on management of patients with suspected recurrent colorectal cancer. The major benefit of PET is avoidance of inappropriate local therapies by documentation of widespread disease.

Inhibition of Chk1-dependent G2 DNA damage checkpoint radiosensitizes p53 mutant human cells

Cell cycle checkpoints are surveillance mechanisms that monitor and coordinate the order and fidelity of cell cycle events. When defects in the division program of a cell are detected, checkpoints prevent the pursuant cell cycle transition through regulation of the relevant cyclin-cdk complex(es). Checkpoints that respond to DNA damage have been described for the G1, S and G2 phases of the cell cycle. The p53 tumour suppressor is a key regulator of G1/S checkpoints, and can promote cell cycle delay or apoptosis in response to DNA damage. The importance of these events to cellular physiology is highlighted by the fact that tumours, in which p53 is frequently mutated, have widespread defects in the G1/S DNA damage checkpoints and a heightened level of genomic instability. G2/M DNA damage checkpoints have been defined by yeast genetics, though the genes in this response are conserved in mammals. We show here using biochemical and physiological assays that p53 is dispensable for a DNA damage checkpoint activated in the G2 phase of the cell cycle. Moreover, upregulation of p53 through serine 20 phosphorylation, does not occur in G2. Conversely, we show that the Chk1 protein kinase is essential for the human G2 DNA damage checkpoint. Importantly, inhibition of Chk1 in p53 deficient cells greatly sensitizes them to radiation, validating the hypothesis of targeting Chk1 in rational drug design and development for anti-cancer therapies.

Imaging with F-18 FDG PET is superior to Tl-201 SPECT in the staging of non-small cell lung cancer for radical radiation therapy

Thallium-201 (Tl-201) single photon emission computed tomography (SPECT) is funded for evaluation of malignancy in Australia and may have utility for staging of non-small cell lung cancer (NSCLC) if CT results are equivocal. Fluorine-18 fluorodeoxyglucose (F-18 FDG) positron emission tomography (PET) is superior to CT for staging NSCLC but is more expensive and less widely available than Tl-201 SPECT. Therefore, these techniques were prospectively compared in 27 radical radiation therapy candidates. Patients were allocated a conventional, PET and Tl-201 stage. Tumour to background ratios (TBR) were recorded for the primary on both techniques. Metastatic disease was confirmed by surgical pathology, serial imaging or clinical follow up. Tumour to background ratios were consistently higher for FDG PET than Tl-201 SPECT (P < 0.0001). Positron emission tomography detected all known primary tumours but Tl-201 failed to image four primary tumours (15%). In 10 of 18 cases of discordance between PET and Tl-201 SPECT regarding stage, corroboration was available from pathology or disease progression. Positron emission tomography was shown to have a 100% positive predictive value, including all three patients with PET-detected distant metastases (P=0.002). Results indicate that PET is superior to Tl-201 SPECT scanning in the staging of NSCLC for radical radiation therapy, and that the low sensitivity for detection of local and metastatic disease is likely to limit the clinical impact and cost-effectiveness of this technique despite its lower cost.

(18)F-FDG PET provides high-impact and powerful prognostic stratification in staging newly diagnosed non-small cell lung cancer

Survival of lung cancer patients remains poor despite increasingly aggressive treatment. Conventional staging has well-described limitations. (18)F-FDG PET has been shown to stage lung cancer more accurately than does CT scanning, but the impact on patient treatment and outcome is poorly defined. This study evaluated this impact in routine clinical practice within a tertiary oncology facility.

METHODS

For 153 consecutive patients with newly diagnosed non-small cell lung cancer, the treatment plan based on conventional staging methods was compared with the treatment plan based on incorporation of PET findings. Survival was analyzed using the Cox proportional hazards regression model.

RESULTS

For broad groupings of stage, 10% of cases were downstaged and 33% upstaged by PET. When assessable, the PET stage was confirmed in 89% of patients. PET had a high impact on 54 patients (35%), including 34 whose therapy was changed from curative to palliative, 6 whose therapy was changed from palliative to curative, and 14 whose treatment modality was changed but not the treatment intent. For 39 patients (25%), a previously selected therapy was altered because of the PET findings. The Cox model indicated that the pre-PET stage was significantly associated with survival (P = 0.013) but that the post-PET stage provided much stronger prognostic stratification (P < 0.0001) and remained significant after adjustment for treatment delivered.

CONCLUSION

Staging that incorporated PET provided a more accurate prognostic stratification than did staging based on conventional investigations. Further, the additional information provided by PET significantly and appropriately changed management in the majority of patients.

Hypoxia-selective antitumor agents. 16. Nitroarylmethyl quaternary salts as bioreductive prodrugs of the alkylating agent mechlorethamine

Nitrobenzyl quaternary salts of nitrogen mustards have been previously reported as hypoxia-selective cytotoxins. In this paper we describe the synthesis and evaluation of a series of heterocyclic analogues, including pyrrole, imidazole, thiophene, and pyrazole examples, chosen to cover a range of one-electron reduction potentials (from -277 to -511 mV) and substitution patterns. All quaternary salt compounds were less toxic in vitro than mechlorethamine, and all were more toxic under hypoxic than aerobic conditions, although the differentials were highly variable within the series. The most promising analogue, imidazole 2, demonstrated DNA cross-linking selectively in hypoxic RIF-1 cells, and was active in vivo in combination with radiation or cisplatin. However, 2 also produced unpredictable toxicity in vivo, suggestive of nonspecific nitrogen mustard release, and this has restricted further development of these compounds as hypoxia-selective cytotoxins.

High rate of detection of unsuspected distant metastases by pet in apparent stage III non-small-cell lung cancer: implications for radical radiation therapy

PURPOSE

Most radical radiotherapy (RT) candidates with non-small-cell lung cancer (NSCLC) have Stage III disease and ultimately die with distant metastases. We tested the hypothesis that positron emission tomography (PET) using 18-F fluorodeoxyglucose (FDG) would detect more unsuspected metastases in apparent Stage III disease than in Stages I-II.

METHODS AND MATERIALS

Staging FDG-PET was performed for 167 NSCLC patients, with Stage I-III by conventional workup, who were candidates for curative therapy with surgery (n = 8), radical chemo/RT or RT (n = 156), or preoperative chemo/RT (n = 3). Each patient was allocated a conventional "pre-PET stage" and a "post-PET stage" that relied on PET when discordance with conventional staging occurred.

RESULTS

Stage distribution pre-PET was n = 39 (Stage I), n = 28 (Stage II), and n = 100 (Stage III). In 32 patients (19%), PET detected distant metastasis, most commonly abdominal with 17 cases (adrenal, n = 7; liver, n = 4; other, n = 6). Other sites included lung (n = 10) and bone (n = 6). PET-detected metastasis increased with increasing pre-PET stage from I (7.5%) through II (18%) to III (24%, p = 0.016), and, in particular, was significantly higher in Stage III (p = 0.039). Biopsy confirmation was not routine, but progression occurred at PET-detected metastatic sites or other metastatic sites in all but 3 of the 32 patients by last review.

CONCLUSION

PET staging is recommended for radical RT candidates with NSCLC. The highest yield of unexpected distant metastases is observed in Stage III.

Clinical impact of (18)F fluorodeoxyglucose positron emission tomography in patients with non-small-cell lung cancer: a prospective study

PURPOSE

To prospectively study the impact of (18)F fluorodeoxyglucose (FDG) positron emission tomography (PET) on clinical management of patients with non-small-cell lung cancer (NSCLC).

PATIENTS AND METHODS

One hundred five consecutive patients with NSCLC undergoing (18)F FDG PET were analyzed. Before PET, referring physicians recorded scan indication, conventional clinical stage, and proposed treatment plan. PET scan results were reported in conjunction with available clinical and imaging data, including results of computed tomography (CT). Subsequent management and appropriateness of PET-induced changes were assessed by follow-up for at least 6 months or until the patient's death.

RESULTS

Indications for PET were primary staging (n = 59), restaging (n = 34), and suspected malignancy subsequently proven to be NSCLC (n = 12). In 27 (26%) of 105 of cases, PET results led to a change from curative to palliative therapy by upstaging disease extent. Validity of the PET result was established in all but one case. PET appropriately downstaged 10 of 16 patients initially planned for palliative therapy, allowing either potentially curative treatment (four patients) or no treatment (six patients). PET influenced the radiation delivery in 22 (65%) of 34 patients who subsequently received radical radiotherapy. Twelve patients considered probably inoperable on conventional imaging studies were downstaged by PET and underwent potentially curative surgery. PET missed only one primary tumor (5-mm scar carcinoma). CT and PET understaged three of 20 surgical patients (two with N1 lesions < 5 mm and one with unrecognized atrial involvement), and PET missed one small intrapulmonary metastasis apparent on CT. No pathological N2 disease was missed on PET.

CONCLUSION

FDG PET scanning changed or influenced management decisions in 70 patients (67%) with NSCLC. Patients were frequently spared unnecessary treatment, and management was more appropriately targeted.

5-Amino-1-(chloromethyl)-1,2-dihydro-3H-benz[e]indoles: relationships between structure and cytotoxicity for analogues bearing different DNA minor groove binding subunits

A series of 5-amino-seco-CBI compounds, designed for use as effectors for prodrugs, were prepared to study structure-activity relationships for the cytotoxicity of side chain analogues. Compounds were prepared by coupling 1-(chloromethyl)-5-nitro-1, 2-dihydro-3H-benz[e]indole to appropriate carboxylic acids, followed by nitro group reduction, or by coupling suitable 5-amino-protected indolines to alpha,beta-unsaturated acids, followed by deblocking. These AT-specific DNA alkylating agents were evaluated for cytotoxicity in a series of tumor cell lines (AA8, UV4, EMT6, SKOV3). For those analogues bearing an indolecarbonyl side chain, the 5'-methoxy derivative was the most cytotoxic (IC(50) 1.3 nM in AA8 cells, 4 h exposure), comparable to that of the parent CBI-TMI (5', 6',7'-trimethoxyindole) derivative (IC(50) 0.46 nM in the above assay). A subset of solubilized derivatives bearing O(CH(2))(2)NMe(2) substituents were about 10-fold less potent. For compounds containing an acryloyl linker in the side chain, the 4'-methoxycinnamoyl derivative proved the most cytotoxic (IC(50) 0. 09 nM in the above assay). A number of these 5-amino-seco-CBI-TMI analogues (including the solubilized compounds) are of interest both as cytotoxins and as components of amine-based prodrugs designed for tumor-specific activation.

Synthesis of 1-substituted 3-(chloromethyl)-6-aminoindoline (6-amino-seco-CI) DNA minor groove alkylating agents and structure-activity relationships for their cytotoxicity

A series of racemic 6-amino-seco-cyclopropylindole (seco-CI) compounds was prepared by coupling 1-(tert-butyloxycarbonyl)-3-(chloromethyl)-6-nitroindoline with appropriate acids, followed by nitro group reduction, and evaluated for cytotoxicity in AA8, UV4, EMT6, and SKOV3 cell lines. These compounds are of interest due to their close structural relationship to known AT-specific alkylating agents and cytotoxins and also for the possible construction of stable amine-based prodrugs designed for tumor-specific release. Variations included indole or furan side chains with different substituents, sulfonamide or carboxamide linkers, extension of the minor groove binding side chain to two subunits, and the use of a pyrroylacryloyl unit previously reported to give extremely potent analogues. The parent compound, with a trimethoxyindole side chain, was a moderately potent cytotoxin (IC50 = 0.34 microM in AA8 cells, 4 h exposure). A single 5-methoxy group on the indole minor groove binding unit was sufficient to maintain potency, and a series of dimethylaminoethoxy-substituted analogues retained the cytotoxicity of the parent compound, while providing increased aqueous solubility.

N-Substituted 2-(2,6-dinitrophenylamino)propanamides: novel prodrugs that release a primary amine via nitroreduction and intramolecular cyclization

A series of N-dinitrophenylamino acid amides [(4-CONHZ-2, 6-diNO2Ph)N(R)C(X,Y)CONHPhOMe] were prepared as potential bioreductive prodrugs and reduced radiolytically to study their rates of subsequent intramolecular cyclization. Compounds bearing a free NH group (R = H) underwent rapid cyclization in neutral aqueous buffers (t1/2 < 1 min) following 4-electron reduction, with the generation of a N-hydroxydihydroquinoxalinone and concomitant release of 4-methoxyaniline. Amine release from analogous N-methyl analogues (R = Me) was relatively slow. These results are consistent with intramolecular cyclization of a monohydroxylamine intermediate. The high rates of cyclization/extrusion by these very electron-deficient hydroxylamines suggest that the process is greatly accelerated by the presence of an H-bonding "conformational lock" between the anilino NH group and the adjacent o-nitro group (Kirk and Cohen, 1972). Changes in the phenylcarboxamide side chain or in C-methylation in the linking chain had little effect on the rate of cyclization. The model compounds had 1-electron reduction potentials in the range appropriate for cellular reduction (-373 mV for a measured example) and appeared suitable for development as prodrugs that release amine-based effectors following enzymic or radiolytic reduction. Prodrug examples containing 4-aminoaniline mustard and 5-amino-1-(chloromethyl)benz[e]indoline alkylating units were evaluated but were not activated efficiently by cellular nitroreductases. However, cell killing by the radiation-induced reduction of the latter prodrug was demonstrated.

Chk1 complements the G2/M checkpoint defect and radiosensitivity of ataxia-telangiectasia cells

Cells from patients with the human genetic disorder ataxia-telangiectasia (A-T) are defective in the activation of cell cycle checkpoints in response to ionizing radiation damage. In order to understand the role of ATM in checkpoint control we investigated whether Schizosaccaromyces pombe chk1, a protein kinase implicated in controlling the G2 DNA damage checkpoint, might alter the radiosensitive phenotype in A-T cells. The fission yeast chkl gene was cloned into an EBV-based vector under the control of a metallothionein promoter and transfected into A-T lymphoblastoid cells. Induction of chk1 enhanced the survival of an A-T cell line in response to radiation exposure as determined by cell viability and reduction of radiation-induced chromosome aberrations. This can be accounted for at least in part by the restoration of the G2 checkpoint to chk1 expressing cells. There was no evidence that chk1 expression corrected either the G1/S checkpoint or radioresistant DNA synthesis in S phase in these cells. These results suggest that chk1 when overexpressed acts downstream from ATM to restore the G2 checkpoint in these cells and correct the radiosensitive phenotype. These data allow us to dissociate individual checkpoint events and relate them to the radiosensitive phenotype in A-T cells.

Inactivation of a c-Myb/estrogen receptor fusion protein in transformed primary cells leads to granulocyte/macrophage differentiation and down regulation of c-kit but not c-myc or cdc2

Primary murine fetal hemopoietic cells were transformed with a fusion protein consisting of the ligand-binding domain of the estrogen receptor and a carboxyl-terminally truncated c-Myb protein (ERMYB). The ERMYB-transformed hemopoietic cells exhibit an immature myeloid phenotype when grown in the presence of beta-estradiol. Upon removal of beta-estradiol, the ERMYB cells display increased adherence, decreased clonogenicity and differentiate to cells exhibiting granulocyte or macrophage morphology. The expression of the c-myc, c-kit, cdc2 and bcl-2 genes, which are putatively regulated by Myb, was investigated in ERMYB cells grown in the presence or absence of beta-estradiol. Neither c-myc nor cdc2 expression was down-regulated after removal of beta-estradiol demonstrating that differentiation is not a consequence of decreased transactivation of these genes by ERMYB. While bcl-2 expression was reduced by 50% in ERMYB cells grown in the absence of beta-estradiol, there was no increase in DNA laddering, suggesting that Myb was not protecting ERMYB cells from apoptosis. In contrast, a substantial (200-fold) decrease in c-kit mRNA level was observed following differentiation of ERMYB cells, and c-kit mRNA could be partially re-induced by the re-addition of beta-estradiol. Furthermore, a reporter construct containing the c-kit promoter was activated when cotransfected with a Myb expression vector, providing further evidence of a role for Myb in the regulation of c-kit.

Identification of mutations in the retinoblastoma gene

Mutations in the retinoblastoma gene (RBl) predispose to the formation of ocular tumors. Following the cloning of RBI in 1986 (1), polymorphic restriction enzyme sites within RBl were used to "track" the mutant gene within affected families using linkage analysis (2, 3). This approach, however, was unsuitable for most retinoblastoma (Rb) patients because only 16% have a family history of Rb (4). In recent years, it has become possible to detect mutations in nucleic acids. The ability to detect mutations in RBl has important implications for Rb patients because it means that individuals predisposed to Rb but with no previous family history of the disease can now be screened for mutations.

Abnormalities of the RB1 and DCC tumor suppressor genes: uncommon in human pancreatic adenocarcinoma

Evidence of RB1 allele loss was found in only 6% of pancreatic cancers, and we found no significant sequence abnormalities nor loss of RB protein expression in a panel of tumors and cell lines. Using reverse transcription-polymerase chain reaction and Southern blot analysis, we found no evidence for loss of DCC expression in pancreatic cancer cell lines, and allele loss only rarely in tumor biopsies. These findings suggest that abnormalities of RB1 and DCC are unlikely to play a major role in pancreatic carcinogenesis.

Field evaluation of thirteen regimens for the control of progressive atrophic rhinitis

The purpose of the study was to evaluate, under field conditions, the effect of prophylactic programs for the control of progressive atrophic rhinitis (PAR)--recommended in different countries. The investigations were carried out on 280 pregnant sows divided into 14 equal groups and 50 slaughter pigs randomly selected from the litters produced by the sows of each of the groups. Efficacy of all programs was recognized on the basis of comparative evaluation of the average daily gain (ADG), morphometric examination of turbinate bones and computer conchal morphometry (TPR). An increase in ADG was noted in 12 of 13 experimental groups when compared to the control group. Usefulness of the evaluated programs differed significantly. Results of TPR relate only partially to the results of visual morphometry and results of ADG.

Partial inactivation of the RB product in a family with incomplete penetrance of familial retinoblastoma and benign retinal tumors

While familial retinoblastoma has served as the paradigm for the two-hit theory of tumorigenesis and for the concept of the tumor suppressor gene, the etiology of incomplete penetrance of familial retinoblastoma is poorly understood. To address the molecular basis for this phenotype we have studied the functional properties of a mutant Rb gene identified in a kindred with incomplete penetrance of familial retinoblastoma and evidence for regressed retinal lesions (retinomas). In contrast to all previously isolated RB mutant proteins, we demonstrated that the mutant product from this kindred retained the wildtype properties of nuclear localization, the ability to undergo hyperphosphorylation in vivo, and the capacity to suppress growth of RB(-) cells. Protein binding ('pocket') activity, however, was defective defining a new class of RB mutant with partial inactivation. The presence of this unique RB mutant in the germline of obligate carriers with incomplete penetrance and regressed retinal lesions suggests a molecular basis for this phenotype and supports the hypothesis that a minimum 'RB threshold' level of protein binding activity is required to suppress tumorigenesis.

Efficacy of an Actinobacillus pleuropneumoniae bacterin against serotypes 1, 3, 5 and 9

A trial was performed in a swine research facility to ascertain the protection provided by a polyvalent Actinobacillus pleuropneumoniae (APP) bacterin containing serotypes 1, 3, 5 and 9. The test animals consisted of 60, eight-week-old, piglets, which were randomly divided into four main groups. The four main groups were further divided into three sub-groups (I, II, III) of five pigs each. Subgroup I was vaccinated intramuscularly, sub-group II was vaccinated subcutaneously, and sub-group III served as the unvaccinated control group. Each main group was challenged with a single APP serotype (1, 3, 5 or 9). Criteria for evaluation of the bacterin efficacy were mortality, lung lesions, pleural adhesions, and isolation of APP from tonsil or lung. Significant effects of vaccination over nonvaccination were reduced mortality, lung lesions, pleural adhesions, and isolations of APP from tonsil and lung. There were no significant differences between the intramuscular and subcutaneous routes of vaccination. It was concluded that the four-way APP bacterin used in this study provided satisfactory protection against homologous challenge. Evidence of protection was lower mortality and lung lesions and increased daily weight gains in vaccinates as compared with controls.