Cost-effectiveness analysis of add-on pertuzumab to trastuzumab biosimilar and chemotherapy as neoadjuvant treatment for human epidermal growth receptor 2-positive early breast cancer patients in Singapore

OBJECTIVES

The Asian PEONY trial showed that add-on pertuzumab to trastuzumab and chemotherapy significantly improved pathological complete response in the neoadjuvant treatment of patients with human epidermal growth factor receptor 2-positive (HER2+) early breast cancer (EBC). This study evaluated the cost-effectiveness of pertuzumab as an add-on therapy to trastuzumab and chemotherapy for neoadjuvant treatment of patients with HER2+ EBC in Singapore.

METHODS

A six-state Markov model was developed from the Singapore healthcare system perspective, with a lifetime time horizon. Model outputs were: costs; life-years (LYs); quality-adjusted LYs (QALYs); incremental cost-effectiveness ratios (ICERs). Sensitivity/scenario analyses explored model uncertainties.

RESULTS

The base case projected the addition of pertuzumab to be associated with improved outcomes by 0.277 LYs and 0.271 QALYs, increased costs by S$1,387, and an ICER of S$5,121/QALY. The ICER was most sensitive to the pCR rate, and the probabilistic sensitivity analysis showed that add-on pertuzumab had an 81.3% probability of being cost-effective at a willingness-to-pay threshold of S$45,000/QALY gained.

CONCLUSIONS

This model demonstrated that the long-term clinical impact of early pertuzumab use, particularly the avoidance of metastatic disease and thus avoidance of higher costs and mortality rates, make neoadjuvant pertuzumab a cost-effective option in the management of patients with HER2+ breast cancer in Singapore.

Alterations to DNA methylation patterns induced by chemotherapy treatment are associated with negative impacts on the olfactory pathway

BACKGROUND

Exposure to cytotoxic chemotherapy treatment may alter DNA methylation (DNAm) in breast cancer patients.

METHODS

We performed DNAm analysis in 125 breast cancer patients with blood drawn before and after chemotherapy, using the Illumina MethylationEPIC array. DNAm changes of 588,798 individual CpGs (including 41,207 promoter regions) were evaluated using linear regression models adjusted for monocyte proportion. Gene set enrichment analyses (GSEA) were conducted to identify key Gene Ontology (GO) biological processes or Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways associated with chemotherapy. Results were validated in a separate cohort of breast cancer patients who were treated (n = 1273) and not treated (n = 872) by chemotherapy (1808 blood, 337 saliva).

RESULTS

A total of 141 differentially methylated CpGs and 11 promoters were significantly associated with chemotherapy after multiple testing corrections in both the paired sample and single time point analyses. GSEA of promoter regions (pre-ranked by test statistics) identified six suppressed biological processes (p < 4.67e-8) related to sensory perception and detection of chemical stimuli, including smell perception (GO:0007606, GO:0007608, GO:0009593, GO:0050906, GO:0050907, and GO:0050911). The same six biological processes were significantly suppressed in the validation dataset (p < 9.02e-14). The KEGG pathway olfactory transduction (hsa04740) was also found to be significantly suppressed (ppaired-samples = 1.72e-9, psingle-timepoint-blood = 2.03e-15 and psingle-timepoint-saliva = 7.52e-56).

CONCLUSION

The enrichment of imprinted genes within biological processes and pathways suggests a biological mechanism by which chemotherapy could affect the perception of smell.

How Asian Breast Cancer Patients Experience Unequal Incidence of Chemotherapy Side Effects: A Look at Ethnic Disparities in Febrile Neutropenia Rates

The majority of published findings on chemotherapy-induced febrile neutropenia (FN) are restricted to three ethnic groups: Asians, Caucasians, and African Americans. In this two-part study, we examined FN incidence and risk factors in Chinese, Malay, and Indian chemotherapy-treated breast cancer (BC) patients. Hospital records or ICD codes were used to identify patients with FN. In both the Singapore Breast Cancer Cohort (SGBCC) and the Joint Breast Cancer Registry (JBCR), the time of the first FN from the start of chemotherapy was estimated using Cox regression. Multinomial regression was used to evaluate differences in various characteristics across ethnicities. FN was observed in 170 of 1014 patients in SGBCC. The Cox model showed that non-Chinese were at higher risk of developing FN (HR_Malay [95% CI]:2.04 [1.44-2.88], p < 0.001; HR_Indian:1.88 [1.11-3.18], p = 0.018). In JBCR, FN was observed in 965 of 7449 patients. Univariable Cox models identified ethnicity, a lower baseline absolute neutrophil count, non-luminal A proxy subtypes, and anthracycline-containing regimens as risk factors. Disparities across ethnicities' risk (HR_Malay:1.29 [1.07-1.54], p = 0.006; HR_Indian:1.50 [1.19-1.88], p < 0.001) remained significant even after further adjustments. Finally, an age-adjusted multinomial model showed that Malays (p = 0.006) and Indians (p = 0.009) were significantly more likely to develop multiple episodes of FN during treatment. Ethnic differences in chemotherapy-induced FN among BC patients exist. Further studies can focus on investigating pharmacogenetic differences across ethnicities.

Pan-Asian adapted ESMO Clinical Practice Guidelines for the diagnosis, staging and treatment of patients with metastatic breast cancer

The most recent version of the European Society for Medical Oncology (ESMO) Clinical Practice Guidelines for the diagnosis, staging and treatment of patients with metastatic breast cancer (MBC) was published in 2021. A special, hybrid guidelines meeting was convened by ESMO and the Korean Society of Medical Oncology (KSMO) in collaboration with nine other Asian national oncology societies in May 2022 in order to adapt the ESMO 2021 guidelines to take into account the differences associated with the treatment of MBC in Asia. These guidelines represent the consensus opinions reached by a panel of Asian experts in the treatment of patients with MBC representing the oncological societies of China (CSCO), India (ISMPO), Indonesia (ISHMO), Japan (JSMO), Korea (KSMO), Malaysia (MOS), the Philippines (PSMO), Singapore (SSO), Taiwan (TOS) and Thailand (TSCO). The voting was based on the best available scientific evidence and was independent of drug access or practice restrictions in the different Asian countries. The latter were discussed when appropriate. The aim of these guidelines is to provide guidance for the harmonisation of the management of patients with MBC across the different regions of Asia, drawing from data provided by global and Asian trials whilst at the same time integrating the differences in genetics, demographics and scientific evidence, together with restricted access to certain therapeutic strategies.

Will Absolute Risk Estimation for Time to Next Screen Work for an Asian Mammography Screening Population?

Personalized breast cancer risk profiling has the potential to promote shared decision-making and improve compliance with routine screening. We assessed the Gail model's performance in predicting the short-term (2- and 5-year) and the long-term (10- and 15-year) absolute risks in 28,234 asymptomatic Asian women. Absolute risks were calculated using different relative risk estimates and Breast cancer incidence and mortality rates (White, Asian-American, or the Singapore Asian population). Using linear models, we tested the association of absolute risk and age at breast cancer occurrence. Model discrimination was moderate (AUC range: 0.580-0.628). Calibration was better for longer-term prediction horizons (E/O_{long-term ranges}: 0.86-1.71; E/O_{short-term ranges}:1.24-3.36). Subgroup analyses show that the model underestimates risk in women with breast cancer family history, positive recall status, and prior breast biopsy, and overestimates risk in underweight women. The Gail model absolute risk does not predict the age of breast cancer occurrence. Breast cancer risk prediction tools performed better with population-specific parameters. Two-year absolute risk estimation is attractive for breast cancer screening programs, but the models tested are not suitable for identifying Asian women at increased risk within this short interval.

Abstract P6-01-44: Alteration of DNA methylation landscape in breast patients treated with adjuvant chemotherapy

Background Exposure to cytotoxic chemotherapy treatment may alter DNA methylation (DNAm) in treated patients. Methods We performed DNAm analysis in 1,244 and 897 breast cancer patients treated and not treated by adjuvant chemotherapy using the Illumina MethylationEPIC array (1,804 blood, 337 saliva). DNAm changes of 620,095 individual CpGs and 41,581 promoters were evaluated using linear regression models, adjusting for age at diagnosis, ethnicity, years between sample collection and diagnosis and cell-type heterogeneity. Results from datasets normalized separately were combined by meta-analysis (random effects model). Gene set enrichment analyses were conducted to identify key processes or pathways associated with chemotherapy treatment. Results A total of 425 differentially methylated CpGs and 20 promoters were significantly associated with chemotherapy treatment (p&lt; 5e-8). Enriched gene sets among 3,495 chemotherapy-associated promoters (unadjusted p&lt; 0.05, preranked by Z scores) included three suppressed Gene Ontology (GO) terms that survived Bonferroni correction (GO:0002376, immune system process; GO:0009605, response to external stimulus; and GO:1903034: regulation of response to wounding). Using meta-analysis regression coefficients for all promoters as a ranking metric, olfactory transduction (KEGG, hsa04740) was found to be significantly suppressed (unadjusted p=6.38e-06, adjusted p=0.002). Taste transduction (hsa04742, unadjusted p=1.73e-03, adjusted p=0.565) was the next most significantly suppressed pathway. Conclusion The enrichment of imprinted genes within biological processes and pathways suggests a biological mechanism by which chemotherapy treatment could affect immune response, wound healing and changes in the perceptions of smell and taste.

Citation Format: Peh Joo Ho, Alexis Jiaying Khng, Benita Kiat Tee Tan, Ern Yu Tan, Geok hoon Lim, Su-Ming Tan, Veronique Kiak Mien Tan, Elaine Hsuen Lim, Mikael Hartman, Jingmei Li. Alteration of DNA methylation landscape in breast patients treated with adjuvant chemotherapy [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P6-01-44.

Ironing out exercise on immuno-oncological outcomes

Despite accumulating evidence that supports the beneficial effects of physical exercise in inhibiting cancer progression, whether exercise modulates its effects through systemic and cellular changes in iron metabolism and immune-tumor crosstalk is unknown. Cancer cells have greater metabolic requirements than normal cells, with their survival and proliferation depending largely on iron bioavailability. Although iron is an essential mineral for mitogenesis, it also participates in a form of iron-dependent programmed cell death termed ferroptosis. In this short hypothesis paper, we speculate that modulating iron bioavailability, transport and metabolism with regular exercise can have significant implications for tumor and stromal cells in the tumor microenvironment, by affecting multiple tumor-autonomous and stromal cell responses.

Association between Breast Cancer Polygenic Risk Score and Chemotherapy-Induced Febrile Neutropenia: Null Results

BACKGROUND

The hypothesis that breast cancer (BC) susceptibility variants are linked to chemotherapy-induced toxicity has been previously explored. Here, we investigated the association between a validated 313-marker-based BC polygenic risk score (PRS) and chemotherapy-induced neutropenia without fever and febrile neutropenia (FNc) in Asian BC patients.

METHODS

This observational case-control study of Asian BC patients treated with chemotherapy included 161 FNc patients, 219 neutropenia patients, and 936 patients who did not develop neutropenia. A continuous PRS was calculated by summing weighted risk alleles associated with overall, estrogen receptor- (ER-) positive, and ER-negative BC risk. PRS distributions neutropenia or FNc cases were compared to controls who did not develop neutropenia using two-sample t-tests. Odds ratios (OR) and corresponding 95% confidence intervals were estimated for the associations between PRS (quartiles and per standard deviation (SD) increase) and neutropenia-related outcomes compared to controls.

RESULTS

PRS distributions were not significantly different in any of the comparisons. Higher PRS_overall quartiles were negatively correlated with neutropenia or FNc. However, the associations were not statistically significant (PRS per SD increase OR neutropenia: 0.91 [0.79-1.06]; FNc: 0.87 [0.73-1.03]). No dose-dependent trend was observed for the ER-positive weighted PRS (PRS_ER-pos) and ER-negative weighted PRS (PRS_ER-neg).

CONCLUSION

BC PRS was not strongly associated with chemotherapy-induced neutropenia or FNc.

Overlap of high-risk individuals predicted by family history, and genetic and non-genetic breast cancer risk prediction models: implications for risk stratification

BACKGROUND

Family history, and genetic and non-genetic risk factors can stratify women according to their individual risk of developing breast cancer. The extent of overlap between these risk predictors is not clear.

METHODS

In this case-only analysis involving 7600 Asian breast cancer patients diagnosed between age 30 and 75 years, we examined identification of high-risk patients based on positive family history, the Gail model 5-year absolute risk [5yAR] above 1.3%, breast cancer predisposition genes (protein-truncating variants [PTV] in ATM, BRCA1, BRCA2, CHEK2, PALB2, BARD1, RAD51C, RAD51D, or TP53), and polygenic risk score (PRS) 5yAR above 1.3%.

RESULTS

Correlation between 5yAR (at age of diagnosis) predicted by PRS and the Gail model was low (r=0.27). Fifty-three percent of breast cancer patients (n=4041) were considered high risk by one or more classification criteria. Positive family history, PTV carriership, PRS, or the Gail model identified 1247 (16%), 385 (5%), 2774 (36%), and 1592 (21%) patients who were considered at high risk, respectively. In a subset of 3227 women aged below 50 years, the four models studied identified 470 (15%), 213 (7%), 769 (24%), and 325 (10%) unique patients who were considered at high risk, respectively. For younger women, PRS and PTVs together identified 745 (59% of 1276) high-risk individuals who were not identified by the Gail model or family history.

CONCLUSIONS

Family history and genetic and non-genetic risk stratification tools have the potential to complement one another to identify women at high risk.

Multi-center evaluation of artificial intelligent imaging and clinical models for predicting neoadjuvant chemotherapy response in breast cancer

BACKGROUND

Neoadjuvant chemotherapy (NAC) plays an important role in the management of locally advanced breast cancer. It allows for downstaging of tumors, potentially allowing for breast conservation. NAC also allows for in-vivo testing of the tumors' response to chemotherapy and provides important prognostic information. There are currently no clearly defined clinical models that incorporate imaging with clinical data to predict response to NAC. Thus, the aim of this work is to develop a predictive AI model based on routine CT imaging and clinical parameters to predict response to NAC.

METHODS

The CT scans of 324 patients with NAC from multiple centers in Singapore were used in this study. Four different radiomics models were built for predicting pathological complete response (pCR): first two were based on textural features extracted from peri-tumoral and tumoral regions, the third model based on novel space-resolved radiomics which extract feature maps using voxel-based radiomics and the fourth model based on deep learning (DL). Clinical parameters were included to build a final prognostic model.

RESULTS

The best performing models were based on space-resolved and DL approaches. Space-resolved radiomics improves the clinical AUCs of pCR prediction from 0.743 (0.650 to 0.831) to 0.775 (0.685 to 0.860) and our DL model improved it from 0.743 (0.650 to 0.831) to 0.772 (0.685 to 0.853). The tumoral radiomics model performs the worst with no improvement of the AUC from the clinical model. The peri-tumoral combined model gives moderate performance with an AUC of 0.765 (0.671 to 0.855).

CONCLUSIONS

Radiomics features extracted from diagnostic CT augment the predictive ability of pCR when combined with clinical features. The novel space-resolved radiomics and DL radiomics approaches outperformed conventional radiomics techniques.

Special Histologic Type and Rare Breast Tumors - Diagnostic Review and Clinico-Pathological Implications

Breast cancer is the most common malignant tumor in females. While most carcinomas are categorized as invasive carcinoma, no special type (NST), a diverse group of tumors with distinct pathologic and clinical features is also recognized, ranging in incidence from relatively more common to rare. So-called "special histologic type" tumors display more than 90% of a specific, distinctive histologic pattern, while a spectrum of tumors more often encountered in the salivary gland may also arise in the breast. Metaplastic carcinomas can present diagnostic challenges. Some uncommon tumors harbor pathognomonic genetic alterations. This article provides an overview of the key diagnostic points and differential diagnoses for this group of disparate lesions, as well as the salient clinical characteristics of each entity.

The Role of the Extracellular Matrix and Tumor-Infiltrating Immune Cells in the Prognostication of High-Grade Serous Ovarian Cancer

Ovarian cancer is the eighth global leading cause of cancer-related death among women. The most common form is the high-grade serous ovarian carcinoma (HGSOC). No further improvements in the 5-year overall survival have been seen over the last 40 years since the adoption of platinum- and taxane-based chemotherapy. Hence, a better understanding of the mechanisms governing this aggressive phenotype would help identify better therapeutic strategies. Recent research linked onset, progression, and response to treatment with dysregulated components of the tumor microenvironment (TME) in many types of cancer. In this study, using bioinformatic approaches, we identified a 19-gene TME-related HGSOC prognostic genetic panel (19 prognostic genes (PLXNB2, HMCN2, NDNF, NTN1, TGFBI, CHAD, CLEC5A, PLXNA1, CST9, LOXL4, MMP17, PI3, PRSS1, SERPINA10, TLL1, CBLN2, IL26, NRG4, and WNT9A) by assessing the RNA sequencing data of 342 tumors available in the TCGA database. Using machine learning, we found that specific patterns of infiltrating immune cells characterized each risk group. Furthermore, we demonstrated the predictive potential of our risk score across different platforms and its improved prognostic performance compared with other gene panels.

Germline breast cancer susceptibility genes, tumor characteristics, and survival

BACKGROUND

Mutations in certain genes are known to increase breast cancer risk. We study the relevance of rare protein-truncating variants (PTVs) that may result in loss-of-function in breast cancer susceptibility genes on tumor characteristics and survival in 8852 breast cancer patients of Asian descent.

METHODS

Gene panel sequencing was performed for 34 known or suspected breast cancer predisposition genes, of which nine genes (ATM, BRCA1, BRCA2, CHEK2, PALB2, BARD1, RAD51C, RAD51D, and TP53) were associated with breast cancer risk. Associations between PTV carriership in one or more genes and tumor characteristics were examined using multinomial logistic regression. Ten-year overall survival was estimated using Cox regression models in 6477 breast cancer patients after excluding older patients (≥75years) and stage 0 and IV disease.

RESULTS

PTV9genes carriership (n = 690) was significantly associated (p < 0.001) with more aggressive tumor characteristics including high grade (poorly vs well-differentiated, odds ratio [95% confidence interval] 3.48 [2.35-5.17], moderately vs well-differentiated 2.33 [1.56-3.49]), as well as luminal B [HER-] and triple-negative subtypes (vs luminal A 2.15 [1.58-2.92] and 2.85 [2.17-3.73], respectively), adjusted for age at diagnosis, study, and ethnicity. Associations with grade and luminal B [HER2-] subtype remained significant after excluding BRCA1/2 carriers. PTV25genes carriership (n = 289, excluding carriers of the nine genes associated with breast cancer) was not associated with tumor characteristics. However, PTV25genes carriership, but not PTV9genes carriership, was suggested to be associated with worse 10-year overall survival (hazard ratio [CI] 1.63 [1.16-2.28]).

CONCLUSIONS

PTV9genes carriership is associated with more aggressive tumors. Variants in other genes might be associated with the survival of breast cancer patients. The finding that PTV carriership is not just associated with higher breast cancer risk, but also more severe and fatal forms of the disease, suggests that genetic testing has the potential to provide additional health information and help healthy individuals make screening decisions.

Breast cancer risk stratification for mammographic screening: A nation-wide screening cohort of 24,431 women in Singapore

Background

Breast cancer incidence is increasing in Asia. However, few women in Singapore attend routine mammography screening. We aim to identify women at high risk of breast cancer who will benefit most from regular screening using the Gail model and information from their first screen (recall status and mammographic density).

Methods

In 24,431 Asian women (50–69 years) who attended screening between 1994 and 1997, 117 developed breast cancer within 5 years of screening. Cox proportional hazard models were used to study the associations between risk classifiers (Gail model 5‐year absolute risk, recall status, mammographic density), and breast cancer occurrence. The efficacy of risk stratification was evaluated by considering sensitivity, specificity, and the proportion of cancers identified.

Results

Adjusting for information from first screen attenuated the hazard ratios (HR) associated with 5‐year absolute risk (continuous, unadjusted HR [95% confidence interval]: 2.3 [1.8–3.1], adjusted HR: 1.9 [1.4–2.6]), but improved the discriminatory ability of the model (unadjusted AUC: 0.615 [0.559–0.670], adjusted AUC: 0.703 [0.653–0.753]). The sensitivity and specificity of the adjusted model were 0.709 and 0.622, respectively. Thirty‐eight percent of all breast cancers were detected in 12% of the study population considered high risk (top five percentile of the Gail model 5‐year absolute risk [absolute risk ≥1.43%], were recalled, and/or mammographic density ≥50%).

Conclusion

The Gail model is able to stratify women based on their individual breast cancer risk in this population. Including information from the first screen can improve prediction in the 5 years after screening. Risk stratification has the potential to pick up more cancers.

Fatty acid oxidation is a druggable gateway regulating cellular plasticity for driving metastasis in breast cancer

Cell state transitions control the functional behavior of cancer cells. Epithelial-to-mesenchymal transition (EMT) confers cancer stem cell-like properties, enhanced tumorigenicity and drug resistance to tumor cells, while mesenchymal-epithelial transition (MET) reverses these phenotypes. Using high-throughput chemical library screens, retinoids are found to be potent promoters of MET that inhibit tumorigenicity in basal-like breast cancer. Cell state transitions are defined by reprogramming of lipid metabolism. Retinoids bind cognate nuclear receptors, which target lipid metabolism genes, thereby redirecting fatty acids for β-oxidation in the mesenchymal cell state towards lipid storage in the epithelial cell state. Disruptions of key metabolic enzymes mediating this flux inhibit MET. Conversely, perturbations to fatty acid oxidation (FAO) rechannel fatty acid flux and promote a more epithelial cell phenotype, blocking EMT-driven breast cancer metastasis in animal models. FAO impinges on the epigenetic control of EMT through acetyl-CoA-dependent regulation of histone acetylation on EMT genes, thus determining cell states.

Cost-effectiveness of pertuzumab and trastuzumab biosimilar combination therapy as initial treatment for HER2-positive metastatic breast cancer in Singapore

BACKGROUND

This study evaluates the cost-effectiveness of pertuzumab with trastuzumab biosimilar and docetaxel as initial treatment for HER2-positive metastatic breast cancer (MBC) in Singapore.

METHODS

A partitioned survival model with three health states was developed to evaluate the cost-effectiveness of trastuzumab biosimilar and docetaxel with or without pertuzumab from a healthcare system perspective over a 15-year time horizon for patients with HER2-positive MBC. Key clinical inputs were derived from the CLEOPATRA trial. Health state utilities were derived from the literature and direct medical costs were obtained from local public healthcare institutions.

RESULTS

The base-case resulted in an incremental cost-effectiveness ratio (ICER) of SGD366,658 (USD272,244) per quality-adjusted life-year (QALY) gained. One-way sensitivity analyses showed that the ICER was sensitive to utilities in the progression-free state, price of pertuzumab and time horizon. When the price for trastuzumab reference biologic (branded) was applied, the ICER was even higher (SGD426,996 [USD317,045]/QALY).

CONCLUSION

Although trastuzumab biosimilar reduced the cost of the pertuzumab combination regimen, the ICER remained high and was not cost effective in Singapore's context. As pertuzumab contributed 80% of the overall combination treatment cost, price reductions for pertuzumab will be required to improve the cost-effectiveness of combination treatment to an acceptable level.

Efficacy, patterns of use and cost of Pertuzumab in the treatment of HER2+ metastatic breast cancer in Singapore: The National Cancer Centre Singapore experience

BACKGROUND

Pertuzumab is a humanized anti-human epidermal growth factor receptor 2 (HER2) monoclonal antibody found in a Phase III clinical trial to significantly improve median survival in HER2 positive metastatic breast cancer (MBC) when used in combination with a taxane and Trastuzumab, and its clinical efficacy has transformed the therapeutic landscape of HER2-positive breast cancer. There are currently few reports on the pattern of use and value of Pertuzumab in real world settings. Our study describes the clinical efficacy and treatment costs of Pertuzumab in HER2-positive MBC treated in a tertiary cancer centre in Singapore in a predominantly Asian population.

AIM

To investigate the clinical efficacy and treatment costs of Pertuzumab in HER2-positive MBC in an Asian population in Singapore.

METHODS

A retrospective study of 304 HER2-positive MBC patients seen at National Cancer Centre Singapore between 2011-2017 was conducted. Demographic and clinical data were extracted from electronic medical records. Clinical characteristics and billing data of patients who received Pertuzumab were compared with those who did not.

RESULTS

Thirty-one (62.0%) of the fifty (16.4%) patients who received Pertuzumab as first-line therapy. With a median follow-up of 21.5 mo, there was a statistically significant difference in the median overall survival between Pertuzumab and non-Pertuzumab groups [51.5 (95%CI: 35.8–60.0) vs 32.9 (95%CI: 28.1–37.5) mo; P = 0.0128]. Two (4.88%) patients in the Pertuzumab group experienced grade 3 (G3) cardiotoxicity. The median treatment cost incurred for total chemotherapy for the Pertuzumab group was 130456 Singapore Dollars compared to 34523 Singapore Dollars for the non-Pertuzumab group. The median percentage of total chemotherapy costs per patient in the Pertuzumab group spent on Pertuzumab was 50.3%.

CONCLUSION

This study shows that Pertuzumab use in the treatment of metastatic breast cancer is associated with a significantly better survival and a low incidence of serious cardiotoxicity. However, the proportionate cost of Pertuzumab therapy remains high and further cost-effectiveness studies should be conducted.

Detection and prognostic relevance of circulating tumour cells (CTCs) in Asian breast cancers using a label-free microfluidic platform

Objectives

We aimed to study the prevalence of CTCs in breast cancer (BC) patients undergoing neoadjuvant or palliative therapy with a label-free microfluidic platform (ClearCell FX), and its prognostic relevance in metastatic BC (mBC).

Materials and methods

Peripheral blood samples were collected from 108 BC patients before starting a new line of treatment (“baseline”), majority of whom had mBC (76/108; 70.4%). CTCs were retrieved by dean flow fractionation that enriched for larger cells, and enumerated using immunofluorescence-based staining. Progression-free survival (PFS) in mBC patients was analysed using Kaplan-Meier method; cox proportional hazard models were used for univariable and multivariable analyses.

Results

The detection rate of CTCs before starting a new line of treatment was 75.9% (n = 108; median: 8 CTCs/7.5 ml blood) at a cut off of ≥2 CTCs. PFS was inferior for mBC patients with baseline CTC count ≥5 CTCs/7.5 ml blood vs. those with < 5 CTCs/7.5 ml blood (median PFS: 4.3 vs. 7.0 months; p-value: 0.037). The prognostic relevance of CTCs was most significant in patients with HER2^- mBC (median PFS: 4.1 vs. 8.3 months; p-value: 0.032), luminal (HR+HER2-) subtype (median PFS: 4.2 vs. 8.3 months; p-value: 0.048), and patients who had one or more prior treatments (median PFS: 4.2 vs. 7.0 months; p-value: 0.02). On multivariable analysis, baseline CTC level (hazard ratio (HR): 1.84, p-value: 0.02) and pre-treatment status (HR: 1.87, p-value: 0.05) were independent predictors of PFS.

Conclusions

This work demonstrates the prognostic significance of CTCs in mBC detected using a label-free size-based enrichment platform.

Prognostic value of CD8 + PD-1+ immune infiltrates and PDCD1 gene expression in triple negative breast cancer

The role of programmed cell death protein-1 (PD-1)/programmed cell death ligand 1 (PD-L1) in triple negative breast cancer (TNBC) remains to be fully understood. In this study, we investigated the role of PD-1 as a prognostic marker for TNBC in an Asian cohort (n = 269). Samples from patients with TNBC were labeled with antibodies against PD-L1 and PD-1, and subjected to NanoString assays to measure the expression of immune-related genes. Associations between disease-free survival (DFS), overall survival (OS) and biomarker expression were investigated. Multivariate analysis showed that tumors with high PD-1⁺ immune infiltrates harbored significantly increased DFS, and this increase was significant even after controlling for clinicopathological parameters (HR 0.95; P = 0.030). In addition, the density of cells expressing both CD8 and PD-1, but not the density of CD8⁻PD-1⁺ immune infiltrates, was associated with improved DFS. Notably, this prognostic significance was independent of clinicopathological parameters and the densities of total CD8⁺ cell (HR 0.43, P = 0.011). At the transcriptional level, high expression of PDCD1 within the tumor was significantly associated with improved DFS (HR 0.38; P = 0.027). In line with these findings, high expression of IFNG (HR 0.38; P = 0.001) and IFN signaling genes (HR 0.46; p = 0.027) was also associated with favorable DFS. Inclusion of PD-1 immune infiltrates and PDCD1 gene expression added significant prognostic value for DFS (ΔLRχ² = 6.35; P = 0.041) and OS (ΔLRχ² = 9.53; P = 0.008), beyond that provided by classical clinicopathological variables. Thus, PD-1 mRNA and protein expression status represent a promising, independent indicator of prognosis in TNBC.

Abstract 5008: Elucidating HER2 molecular heterogeneity of circulating tumor cells among breast cancer patients

Background: HER2-positive tumors are often associated with poor prognosis, chemo-resistances and some patients eventually develop refractory disease during HER2 targeted therapy. While different mechanisms of trastuzumab resistance are being identified in recent years, contribution of confounding factors such as inherent genomic heterogeneity, equivocal HER2 amplifications and presence of chromosome 17 polysomy has been less understood thus far. In this pilot study, we aim to examine HER2 heterogeneity in CTCs obtained from breast cancer patients in the Asian population setting.

Methods: CTCs were enriched from blood samples using a label-free spiral microfluidics-based ClearCell® FX system. A total of 26 samples were collected from patients diagnosed with HER2 positive (17/26) and HER2 negative (9/26) breast cancer. The enriched CTCs were analyzed using conventional diagnostic modalities (fluorescence in-situ hybridisation (FISH) and immunocytochemistry) to examine HER2 status. Concordance rate between CTCs and matched primary tumor was evaluated.

Results: HER2-positive CTCs were successfully identified in 14 out of 17 HER2+ patients (82.4%); HER2 gene amplification and chromosome 17 polysomy were observed in 10(58.8%) and 13(76.5%) patients respectively. HER2+ CTC counts ranged from 2 to 30 cells from 7.5ml blood (median: 4 HER2+ CTCs/7.5ml). HER2 amplification was not observed in any of the 9 patients with HER2-negative tumors, though 5 out of 9 patients (55.6%) were identified with CTCs harbouring gain in chromosome 17 (median: 2 HER2+ CTCs/7.5ml). A “false positive” cut-off of more than 2 cells/7.5ml blood were established using receiver operating characteristic (ROC) curve analysis and a concordance rate of approximately 70% between paired tumor tissue and CTC among the 26 patients. Immunofluorescence labelling of CTCs with cytokeratin, CD45 and HER2 antibodies further revealed heterogeneity in HER2 expression on CTCs.

Conclusion: CTCs capture the heterogeneity of breast cancer, and could potentially overcome limitations of tissue biopsy which are site specific. HER2- patients, as confirmed by tissue biopsy, with HER2+ CTCs pose interesting questions while determining treatment regime.

Citation Format: Man Chun Leong, Tse Hui Lim, Chye Ling Tan, Yong Wei Chua, Elaine Hsuen Lim, Kiley Wei Jen Loh, Guek Eng Lee, Rebecca Dent, Raymond Chee Hui Ng, Andrew Wu, Wan-Teck Lim, Alvin Soon-Tiong Lim, Yoon-Sim Yap. Elucidating HER2 molecular heterogeneity of circulating tumor cells among breast cancer patients. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 5008.

CT angiography versus Digital Subtraction angiography for intracranial vascular pathology in a clinical setting

No abstract available.

A blood-based epigenetic test for early detection of nasopharyngeal carcinoma (NPC)

6063

Background: NPC is highly curable in early stages but 70% of NPC patients are diagnosed with advanced disease due to lack of effective screening. Genetic and epigenetic alterations involved in the pathogenesis of NPC are known. The higher order chromosomal structures reflecting aberrant transcriptional states of these genes can be measured via techniques such as chromosome conformation capture. Detection of these changes in peripheral blood may provide an accurate test for the early cancer detection. Methods: Blood samples have been collected from 84 patients with histologically confirmed NPC and 100 matched controls. Samples from 45 NPC patients and 68 controls have been analyzed. Fourteen genes known to be dysregulated in NPC were investigated. Potential higher order juxtaposition sites in the candidate genes were predicted using pattern recognition software. PCR primer sets were designed around the chosen sites to screen potential markers. Twenty-two markers showing predictability between NPC and control samples were analysed for optimal reproducibility using alternative primer sets. The optimal sets of markers were then tested amongst the complete set of samples. The dataset was processed by re-sampling using the synthetic minority oversampling technique. The overall sample was split into two groups (66% training set and 34% test set) in the classification. Results: Sixteen markers from 7 candidate genes were found to be optimal in differentiating between NPC and control samples in the first 103 samples. Using the multilayer perceptron (MLP) classification, the following results were obtained: Sensitivity 88.9%, 95% CI (79.2% - 98.6%); Specificity 72.7%, 95% CI (58.9% - 86.5%); PPV 72.7%, 95% CI (58.9% - 86.5%); NPV 88.9%, 95% CI (79.2% - 98.6%). The accuracy of the test was similar in detection of stage I and II NPC versus that of stage III or IV NPC. Conclusions: Using a PCR-based method to detect alterations in the cancer epigenome, the feasibility of developing a blood test of potential utility in early diagnosis of NPC was demonstrated. Analysis of larger numbers of patient samples and optimization of markers are ongoing. The performance characteristics of the test in the total population of 184 samples will be presented.

Abstract 487: Evidence for tumor initiating stem cells in lung cancer

Despite advances in our knowledge of the genetics of cancer and some progress in cancer treatment over the last few decades, lung cancer remains the leading cause of cancer mortality worldwide. Therefore the identification of new therapeutic targets is necessary and important.

By applying xeno-transplantation of primary cells from lung cancer specimens into immune deficient mice, we have identified a subpopulation of cells that can form tumor in transplanted mice which histologically resemble the primary tumor. This subpopulation can be enriched 200 fold for tumor initiating cells (TICs) by sorting primary tumor cells with a specific cell surface marker. The TIC population can give rise to unique epithelial colonies when seeded on feeders. Primary tumor cells when cultured serum free with EGF and FGF give rise to tumor-spheres that contain TICs at greater than 2% frequency. Microarray analysis of TICs from primary tumor samples, xenografts and tumor spheres are analyzed to derive “gene signature” of lung TICs. Several oncogenes and genes in metabolic pathways are overexpressed. Amongst them, LIN28B appears amongst the top list. Knockdown of LIN28B results in reduced tumor growth and, conversely, overexpression of LIN28B leads to transformation of NIH/3T3 and increases clonogenicity of normal lung fibroblasts.

The isolation of lung TICs should facilitate further investigation of the cellular origin and carcinogenesis of lung cancers.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 487. doi:10.1158/1538-7445.AM2011-487

Pleiotrophin enhances clonal growth and long-term expansion of human embryonic stem cells

To identify additional growth factors for optimizing propagation of human embryonic stem cells (hESCs), we mined publicly available data sets for the transcriptomes of murine and human ESCs and feeder cells, thereby generating a list of growth factors and complementary receptors. We identified the major pathways previously reported to be important, as well as several new ones. One pathway is the Pleiotrophin (PTN)-Pleiotrophin receptor (PTPRZ1) axis. Murine fibroblasts secrete Ptn, whereas hESCs expressed PTPRZ1, which is downregulated upon differentiation. Depletion of PTPRZ1 resulted in decreased colony formation and lower recovery of hESCs. Supplementation of chemically defined medium for feeder-free propagation of hESCs with PTN allowed higher recovery of hESCs without loss of pluripotency. PTN-PTPRZ1 functions here predominantly via an antiapoptotic effect mediated in part by the activation of Akt. These findings reveal the underlying importance of PTN in hESC survival and its usefulness in the clonal manipulation and large-scale propagation of hESCs. Disclosure of potential conflicts of interest is found at the end of this article.

Single-cell protein diet of a novel recombinant vitellogenin yeast enhances growth and survival of first-feeding tilapia (Oreochromis mossambicus) larvae

Yeast single-cell protein (SCP) is a high-nutrient feed substitute. This study evaluates the dual applications of a novel recombinant Pichia pastoris SMD1168H (SMD) yeast, expressing a tilapia vitellogenin protein (rVtg), as an SCP diet for Artemia and the first-feeding fish larvae. Instar II Artemia fed rVtg, rVtg precultured in 5% fish oil (rVtg-FO), Saccharomyces cerevisiae (SC), or native SMD had greater lipid contents (P < 0.05) than the freshly hatched. Lipid deposition in the Artemia fed rVtg or rVtg-FO was greater (P < 0.05) than in those fed SMD or SC. Diet-induced accumulation of low levels of docosahexaenoic acid [22:6(n-3)] was detected only in Artemia fed the rVtg-based diets. Tilapia (Oreochromis mossambicus) larvae were fed solely yeast diets singly or in combination (d 3-22), or a staggered regimen of yeast (d 3-12) followed by unenriched or yeast-enriched Artemia (d 13-22). The larvae fed rVtg for 22 d increased in length and weight (P < 0.05), whereas those fed SC or SMD suffered growth suppression and high mortality. Such adverse consequences were ameliorated when 50% of SC was substituted with rVtg. The larvae prefed rVtg followed by a dietary switch to Artemia preenriched for 48 h with rVtg or rVtg-FO were greatest in length, had the highest weight gain, and lived the longest. Besides delivering rVtg protein, essential fatty acids and amino acids, rVtg may have probiotic effects in enhancing larval survival. This study suggests the feasibility of using the rVtg yeast as an Artemia booster and an SCP first feed for larvae.

Expression of recombinant vitellogenin in the yeast Pichia pastoris

Vitellogenin (Vtg) plays vital roles as precursor to the yolk proteins and as carrier for lipids, carbohydrates, phosphates, metal ions, vitamins, and hormones into the oocytes during the massive deposition of yolk nutrients for subsequent nourishment of the developing embryos. Reproductive success is highly sensitive to the nutritional quality of the broodstock diet, which greatly affects the egg and larval viability. We present a novel strategy for genetically engineering a Pichia pastoris yeast strain that constitutively produces recombinant Vtg (rVtg), for application as an enriched feed. The tilapia Oreochromis aureus Vtg (OaVtg) cDNA (5.3 kb) was cloned into a nonsecretory pGAPZA vector. Clones containing up to 31 copies of glyceraldehyde-3-phosphate dehydrogenase (GAP)-promoter-driven Vtg expression cassettes were isolated. These clones expressed a membrane-associated intracellular rVtg protein of 194 kDa, constituting up to 1.16% of total protein. To facilitate future purification of rVtg, we explored the possibility of secreting rVtg using the native Vtg secretion signal and the alpha-factor secretion signal of Saccharomyces cerevisiae. However, neither signal promoted the secretion of rVtg. The clones maximally expressed rVtg at 23 degrees C, reaching a peak at 22 h in shake flasks and 16 h in a fermentor. The clones exhibited a significant increase in essential amino acids and long-chain polyunsaturated fatty acids, which are important for its application as a high-quality nutrient feed.

Oxaliplatin/fluorouracil/leucovorin in advanced colorectal carcinoma: an asian experience

BACKGROUND

Oxaliplatin/fluorouracil/leucovorin (FOLFOX4) is an effective and generally well-tolerated regimen in Western studies of metastatic colorectal carcinoma.

OBJECTIVE

To evaluate the objective tumor responses and toxicities of the FOLFOX4 regimen in a predominantly Chinese population with advanced colorectal carcinoma in Singapore.

METHODS

Forty-seven consecutive patients were enrolled in a retrospective study between March 1998 and December 2001. FOLFOX4 was first-line treatment in 36% of these patients, second-line in 36%, third-line in 17%, and fourth-line in 11%. Tumor responses were assessed radiologically, and toxicities were graded by the National Cancer Institute common toxicity system.

RESULTS

The objective response rate (all partial responses) was 45%, and stable disease was achieved in 35% of the patients. There were no deaths due to toxicity. Mild to moderate peripheral sensory neuropathy affected half of the patients, with 1 report of cold exacerbation in this tropical series. The rate of hypersensitivity reactions to oxaliplatin was 11%, and they usually occurred late in the treatment course.

CONCLUSIONS

FOLFOX4 has good efficacy in metastatic colorectal carcinoma in our local population, but the rate of hypersensitivity reactions to oxaliplatin was high.

Sequence analysis of a fish vitellogenin cDNA with a large phosvitin domain

Vitellogenins (Vtg) are egg-yolk precursor proteins crucial for reproductive success in oviparous animals. We have cloned the first complete cichlid Vtg cDNA from the tilapia fish, Oreochromis aureus. This cDNA has the largest phosvitin (PV) domain amongst piscine Vtgs, being comparable to those of lamprey, Xenopus, and chicken. Thus, the size of PV is independent of the evolutionary advancement of a species. The closer interspecific relationship between O. aureus Vtg1 and Fundulus VtgII than the intraspecific relationship between Fundulus VtgI and II isoforms suggests that teleost ancestors had at least two Vtg isoforms. Contrary to the results of previous phylogenetic inference using Vtgs which indicate that insect lineage is most diverged and nematodes are closer to vertebrate lineage, our results show that nematodes and hexapods form two monophyletic sister groups. Another arthropod taxon, represented by a malacostracan crustacean, Penaeus japonicus, appears to be more closely related to the vertebrates than the hexapods.

Either sufentanil or fentanyl, in addition to intrathecal bupivacaine, provide satisfactory early labour analgesia

PURPOSE

The study was aimed primarily at comparing the duration of analgesia produced by intrathecal fentanyl 25 microg with sufentanil 5 microg when added to bupivacaine 1.25 mg as the initial component of the combined spinal epidural (CSE) technique in early labour.

METHODS

Forty healthy parturients were randomly assigned into two groups to receive either intrathecal sufentanil 5 microg plus bupivacaine 1.25 mg (Group S) or intrathecal fentanyl 25 microg plus bupivacaine 1.25 mg (Group F). Apart from the duration of analgesia, pain scores and side effects were also evaluated.

RESULTS

There was no significant difference in the duration of analgesia (mean 109 +/- SD 49 min in Group F vs 118 +/- 54 min in Group S, P=0.9). Group F had a more rapid onset of analgesia (P <0.05) and a higher cephalad block (median T4 vs T7, P <0.05) in the first 30 min after the block. No difference in the side effects was detected.

CONCLUSION

Fentanyl 25 microg is a good alternative to sufentanil 5 microg when added to bupivacaine 1.25 mg for early labour analgesia.

Spectinomycin inhibits the self-splicing of the group 1 intron RNA

Effects of the aminoglycoside spectinomycin on the self-splicing of primary transcripts of the phage T4 thymidylate synthase gene (td) have been investigated. The kinetic analysis demonstrated that spectinomycin acts as a mixed noncompetitive inhibitor for the td intron RNA with a K(i) of 7.2 mM. Increasing the spectinomycin concentration raised the K(m) values with the corresponding decrease of V(max) and k(cat) values. The specificity of the splicing inhibition by spectinomycin is due to changes in both K(m) and k(cat). The splicing inhibition by spectinomycin is dependent on pH changes and Mg(2+) concentration, indicating electrostatic interactions with the intron RNA. It has been proposed that the key structural features in spectinomycin responsible for the inhibition of splicing may be the hydroxyl groups on the antibiotic.

Magnetic resonance imaging of brain metastases: magnetisation transfer or triple dose gadolinium?

Magnetic resonance (MR) imaging of brain metastases relies on the neovascularity of metastases and the associated breach of blood-brain barrier manifesting as enhancement on T1-weighted images. There are 2 main strategies to improve the detection of brain metastases. One may increase the dose of gadolinium and increase the signal of the lesion. Alternatively, one may also lower the signal of the background (by magnetisation transfer suppression), in which case the enhancing lesion is rendered more conspicuous without increasing the dose of gadolinium. We aim to compare the efficacy of single-dose conventional spin-echo T1 scans with magnetisation transfer (MT) suppression with triple-dose conventional spin-echo T1 scans in the detection of brain metastases in 18 patients undergoing imaging for brain metastases. An incremental dose technique was employed. After administration of a single dose of gadolinium, MT suppressed T1-weighted scans were obtained, followed by a conventional T1 scan. Two doses of gadolinium were subsequently given, achieving a cumulative triple-dose, and a conventional T1-weighted scan was then performed. We found single-dose MT suppressed and triple-dose scans performed equally well and detected 26 metastatic lesions. They detected 5 (5/26, 19%) more lesions than the conventional single-dose T1 scans. Five (5/21, 24%) questionable lesions on single-dose conventional scans were confidently diagnosed on the single-dose MT suppressed and the triple-dose conventional scan. We conclude that single-dose MT suppressed scans are a cost-effective technique of detecting brain metastases.

Short-range linkage relationships, genomic organisation and sequence comparisons of a cluster of five HSP70 genes in Fugu rubripes

Twelve cosmids containing sequences resembling genes encoding members of the 70-kDa heat-shock protein family, HSP70. have been isolated from Fugu rubripes. They can be broadly divided into three groups of overlapping cosmids. Restriction analysis and sequencing of one set of five cosmids have revealed five intronless Fugu HSP70 genes spanning 42 kb, arranged in a combined head-to-head, tail-to-tail and head-to-tail orientation. The levels of DNA and amino acid identity are very high with respect to one another, and are most similar to HSP70 sequences linked to the major histocompatibility complex (MHC) region in other species. Putative heat-shock consensus elements are identified. Non-HSP70 sequences with homology to known genes have been found physically linked to this Fugu HSP70 cluster: the Drosophila melanogaster SOL gene, the Drosophila melanogaster nemo gene, the Caenorhabditis elegans T17E9.1 gene and the sequence encoding the serine protease domain. The linkage relationships described here so far bear no resemblance to those of HSP70 in other organisms. Convergence of mammalian HSP70 and MHC class I and II loci probably occurred after fish had diverged.

A novel piscine vitellogenin gene: structural and functional analyses of estrogen-inducible promoter

The Oreochromis aureus vitellogenin, OaVtg, gene spans 9 kb and contains 34 exons. Its transcription start site is located 15 bp upstream of the translational start codon. Although the OaVtg promoter has a nonconsensus TATA, transient transfection assay showed that this promoter is capable of driving basal transcription. Two imperfect estrogen response elements: EREp (proximal) and EREd (distal) are located in the promoter at - 532 and - 1352, respectively. In competition gel mobility-shift assays, only EREp exhibited specific binding of the recombinant estrogen receptor protein, GST-C/D OaER. Another imperfect ERE (EREexon2) was detected within exon 2 of the OaVtg gene. This is a novel finding for a vitellogenin (Vtg) gene. EREexon2 similarly showed specific recognition of GST-C/D OaER. Both EREp and EREexon2 showed comparable binding affinities as consensus ERE. In transient transfections, the OaVtg promoter, EREp and EREd elicited significant increase in estrogen-dependent synthesis of CAT protein. Hence, we propose that the non-consensus OaVtg EREs contribute to the estrogen-dependent regulation of the OaVtg gene in vivo.

Genomic structure and sequence analysis of the valyl-tRNA synthetase gene of the Japanese pufferfish, Fugu rubripes

The genomic sequence and exon-intron organisation of the valyl-tRNA synthetase gene in the Japanese pufferfish, Fugu rubripes, have been determined. This single-copy Fugu gene spans 8.5 kb, about 2.5 times smaller than that in man (21 kb). It contains 29 exons, with the largest intron being 1008 bp. The predicted polypeptide consists of 1217 amino acids, with a molecular weight of 138 kD and an isoelectric point of 7.27. It shares 40% identity in the overlapping region with its homolog in bacteria, 47% with yeast, and 67% with man. The Fugu gene has an additional N-terminal sequence which shows strong similarity to elongation factory-1gamma, a feature it shares only with the human sequence, but not with any other lower eukaryote or prokaryote studied so far. This N-terminal segment is encoded in the first six exons, suggesting their capture by a translocation through introns. Indeed, the acquisition of extra domains to perform related functions in RNA splicing and translation of polypeptides has already been observed in other aminoacyl-tRNA synthetases. Two cDNA sequences of human valyl-tRNA synthetase have been published, with discrepancies between them. Aided by comparisons with the Fugu gene, three of these discrepancies have been resolved, involving the elucidation of the sequence and positions of two introns. This compact vertebrate genome has demonstrated its value as a tool for the analysis of genes at the genomic level.

Short-range linkage relationships of the valyl-tRNA synthetase gene in Fugu rubripes

The class III region of the human major histocompatibility complex (MHC) is gene-dense, averaging one gene every 10-20 kilobases (kb). Its gene order has been compared with other organisms. To extend this analysis further in another non-mammalian vertebrate, the compact genome of Fugu rubripes was investigated for the existence of orthologues of these class III genes and their relative arrangements. Orthologues of the Mr 70000 heat shock protein (HSP70) and valyl-tRNA synthetase genes have been isolated. They do not seem to be closely physically linked as compared with mammals (supported by longer-range analysis using pulsed field gel electrophoresis). Random shotgun sequencing of the two Fugu cosmids containing the gene encoding valyl-tRNA synthetase revealed sequences resembling genes encoding tenascin-X, the nuclear antigen A/Ro of Sjogren's syndrome, and the Landsteiner-Wiener blood group glycoprotein. These linkage relationships recapitulate some mammalian data, albeit imperfectly. Tenascin-X has been located both in the human and mouse Mhc class III regions. Three copies of a sequence found in the gene encoding Sjogren's syndrome nuclear antigen A/Ro have been identified in the human Mhc class I region; the mouse Mhc class I region contains one copy. It is postulated that a fragmented gene pattern had existed prior to convergence in the ancestral mammalian immune response-related Mhc region, and that some of these genes had belonged to the same linkage group.

Cortisol-induced hepatic vitellogenin mRNA in Oreochromis aureus (Steindachner)

Cortisol triggers rapid but transient transcription of the silent vitellogenin (Vg) gene in male Oreochromis aureus, producing short-lived Vg mRNA. Implantation of cocoa butter containing cortisol at 0.8, 8, 20, and 40 micrograms/g fish body wt induced hepatic Vg mRNA within 1 or 2 hr. Implantation of cortisol at the lowest of these dosages (0.8 micrograms/g body wt) produced a transient surge in serum cortisol within 1 hr. This is equivalent to a 30-fold increase over that of the resting male fish in which the endogenous cortisol levels measured 10.5 +/- 2.39 and 11.4 +/- 3.1 ng/ml, respectively, for fish kept communally or singly. Although sham implantation with cocoa butter also resulted in the elevation of serum cortisol, the rise was much more gradual, only reaching a peak after 6 hr. Thus, parameters like the treatment regime, sampling time intervals after implantation, and the interaction between these two factors can significantly affect the serum cortisol concentrations (P = 0.001). Although implantation of cocoa butter with or without cortisol increased serum cortisol, albeit unsynchronized, Vg mRNA was detected only in the hormone-treated group. The profile of Vg mRNA accumulation appeared to coincide with that of serum cortisol, further suggesting the activating effect of exogenous cortisol on Vg gene. Compared with an earlier study on estradiol-induced Vg gene expression, the action of cortisol was more rapid, but transient. This is reflected in the rapid clearance of the cortisol-induced Vg mRNA and, hence, the lack of plasma Vg protein during cortisol treatment.

Two major groups of vitellogenin cDNA clones from Oreochromis aureus (Steindachner)

cDNA libraries were constructed using livers of male and female Oreochromis aureus that were stimulated with estradiol. Restriction map analyses of vitellogenin (Vg) cDNA clones indicated 4 subgroups with related restriction patterns, represented by pOAVg2 (from female) and pOAVg50, 71 & 87 (from male) fish. With the exception of pOAVg2, all other clones obtained from female fish resembled pOAVg50. There are no internal repeats within these cDNA clones. Southern blot cross-hybridisations distinguished pOAVg87 (group A) from pOAVg2, 50 and 71 (group B). The existence of these 2 major groups of Vg cDNAs was further confirmed by dot blot hybridisations and hybrid melting assays under varying stringencies. The difference of melting temperature, Tm between the 2 groups suggests a 7% intraspecific divergence in the Vg gene family.

Estradiol-induced vitellogenin gene expression in a teleost fish, Oreochromis aureus

Vitellogenesis presents a versatile model for the study of hormone-induced gene expression. We report here the effects of estradiol-17 beta-propionate on vitellogenin gene expression in male Oreochromis aureus, a teleost fish. Vitellogenin mRNA of 6500 nucleotides has been elucidated from the livers of female and estradiol-treated male O. aureus. By hybridization with a specific O. aureus cDNA probe, the vitellogenin mRNA transcript was detected as early as 1 hr following primary and secondary estradiol-stimulations, although for the latter, the rate of accumulation of vitellogenin-specific mRNA was 20-fold higher. The vitellogenin mRNA peaked at 72 and 48 hr, respectively, for primary and secondary stimulations. At the translational level, the increase in plasma vitellogenin was further enhanced during the secondary stimulation. There was a distinct shift in the peak of plasma vitellogenin from Day 14 in the primary induction to Day 3 in the secondary stimulation. The plasma vitellogenin presented in two forms, 300 and 500 kDa, both of which were immunologically confirmed by Western blot analysis to be vitellogenin proteins.

Interaction of chemical and high vascular pressure injury in isolated canine lung

Because both chemical and mechanical insults to the lung may occur concomitantly with trauma, we hypothesized that the pressure threshold for vascular pressure-induced (mechanical) injury would be decreased after a chemical insult to the lung. Normal isolated canine lung lobes (N, n = 14) and those injured with either airway acid instillation (AAI, n = 18) or intravascular oleic acid (OA, n = 25) were exposed to short (5-min) periods of elevated venous pressure (HiPv) ranging from 19 to 130 cmH2O. Before the HiPv stress, the capillary filtration coefficient (Kf,c) was 0.12 +/- 0.01, 0.27 +/- 0.03, and 0.31 +/- 0.02 ml.min-1.cmH2O-1 x 100 g-1 and the isogravimetric capillary pressure (Pc,i) was 9.2 +/- 0.3, 6.8 +/- 0.5, and 6.5 +/- 0.3 cmH2O in N, AAI, and OA lungs, respectively. However, the pattern of response to HiPv was similar in all groups: Kf,c was no different from the pre-HiPv value when the peak venous pressure (Pv) remained less than 55 cmH2O, but it increased reversibly when peak Pv exceeded 55 cmH2O (P less than 0.05). The reflection coefficient (sigma) for total proteins measured after pressure exposure averaged 0.60 +/- 0.03, 0.32 +/- 0.04, and 0.37 +/- 0.09 for N, AAI, and OA lobes respectively. However, in contrast to the result expected if pore stretching had occurred at high pressure, in all groups the sigma measured during the HiPv stress when Pv exceeded 55 cmH2O was significantly larger than that measured during the recovery period.(ABSTRACT TRUNCATED AT 250 WORDS)

Fatty acid modulation of antiestrogen action and antiestrogen-binding protein in cultured lymphoid cells

Nonsteroidal antiestrogens reversibly and specifically inhibited the proliferation of two estrogen receptor-negative lymphoid cell lines (EL4 and Raji) in a dose-dependent manner. [3H]Thymidine incorporation of concanavalin A-stimulated primary splenocytes was also inhibited by 10(-6) M clomiphene (1-[4-(2-diethylaminoethoxy)phenyl]-1,2-diphenyl-2-chloroethylene). The antiproliferative effect could be prevented by the simultaneous presence in the growth medium of 10(-5) M linoleic acid or 10(-5) M arachidonic acid but not by 10(-6) M estradiol. Both lymphoid cell lines had high affinity antiestrogen-binding sites whose affinity could be altered by conditions of growth. Growth of EL4 cells in RPMI 1640 medium supplemented with charcoal-pretreated 5% fetal calf serum (charcoal-stripped medium) resulted in significantly higher affinity (Kd 0.54 nM +/- 0.11 nM; n = 6) than growth in medium supplemented with untreated serum (complete medium) (Kd = 1.68 nM +/- 0.48 nM; n = 6) (p less than 0.001). This change in affinity was partly due to removal of fatty acids from the growth medium by charcoal pretreatment, since addition of 10(-5) M linoleic acid or 10(-5) M gamma-linolenic to charcoal-stripped medium decreased the affinity of the antiestrogen-binding protein. In contrast, growth in 10(-5) M stearic acid or 10(-5) M oleic acid did not significantly alter the affinity of the antiestrogen-binding protein, whereas 10(-5) M palmitic acid significantly increased its affinity. The same fatty acids were also tested for their intrinsic effects on EL4 cell proliferation. Oleic, linoleic and gamma-linolenic acids were growth stimulatory while stearic and palmitic acids were not. Thus linoleic and gamma-linolenic acids whose presence in the growth medium was associated with decreased affinity of [3H]tamoxifen (1-[4-(2-dimethylaminoethoxy)phenyl]-1,2-diphenylbut-1(Z)-ene) binding to the intracellular antiestrogen-binding protein were also growth stimulatory. Unsaturated fatty acids have previously been shown to inhibit binding of [3H]tamoxifen to the antiestrogen-binding protein in a cell-free system. The present observations demonstrate that unsaturated fatty acids also modify the affinity of the antiestrogen-binding protein in intact cells.