Molecular correlates of platinum response in human high-grade serous ovarian cancer patient-derived xenografts

INTRODUCTION

Improvement in the ability to target underlying drivers and vulnerabilities of high-grade serous ovarian cancer (HG-SOC) requires the development of molecularly annotated pre-clinical models reflective of clinical responses.

METHODS

We generated patient-derived xenografts (PDXs) from consecutive, chemotherapy-naïve, human HG-SOC by transplanting fresh human HG-SOC fragments into subcutaneous and intra-ovarian bursal sites of NOD/SCID IL2Rγ(null) recipient mice, completed molecular annotation and assessed platinum sensitivity.

RESULTS

The success rate of xenografting was 83%. Of ten HG-SOC PDXs, all contained mutations in TP53, two were mutated for BRCA1, three for BRCA2, and in two, BRCA1 was methylated. In vivo cisplatin response, determined as platinum sensitive (progression-free interval ≥ 100 d, n = 4), resistant (progression-free interval <100 d, n = 3) or refractory (n = 3), was largely consistent with patient outcome. Three of four platinum sensitive HG-SOC PDXs contained DNA repair gene mutations, and the fourth was methylated for BRCA1. In contrast, all three platinum refractory PDXs overexpressed dominant oncogenes (CCNE1, LIN28B and/or BCL2).

CONCLUSIONS

Because PDX platinum response reflected clinical outcome, these annotated PDXs will provide a unique model system for preclinical testing of novel therapies for HG-SOC.

Effect of RAD21 overexpression on prognosis in KRAS-mutant colorectal carcinomas

453

Background: RAD21 is a component of the cohesion complex and is integral for chromosome segregation and error-free DNA repair. Early studies suggest RAD21 appears to be functionally important in tumour progression and we assessed its clinicopathological and prognostic significance in a cohort of colorectal adenocarcinoma (CRC), and its biological characteristics and cell cell chemosensitivity in vitro. Methods: A multi-institutional study examined RAD21 expression in 652 invasive CRC's. Correlation with clinicopathological factors including gender, differentiation, subtype, nodal status, metastasis and disease specific survival was performed. Correlation with BRAF and KRAS mutation status, p53 accumulation, microsatellite instability, and CpG island methylator phenotype was also undertaken. Cell clones with stable RAD21 knockdown were generated and tested for cellular sensitivity to conventional chemotherapeutic drugs. Results: High RAD21 expression correlated with male gender (56.7% vs. 43.3%), more well differentiated tumours (14.4% vs. 4.0%, p = 0.0001), higher T stage (36.1% vs. 27.0%, p = 0.01), and presence of metastasis (18.8% vs. 12.6%, p =0.03). Both on univariate and multivariate analysis, increased RAD21 expression correlated with worse DSS (hazards ration [HR] 1.4, 95% confidence interval [CI] 1.1 to 1.9, p = 0.01). Subgroup analysis showed RAD21 expression was prognostic in female patients (HR:1.6, 95%CI:1.1-2.3, p = 0.01) and tumours with nodal disease (HR:1.6, 95%CI:1.2-2.2, p = 0.003). RAD21 expression associates worse DSS in patients whose tumors carrying KRAS mutations (HR:2.6, 95%CI:1.4-4.3, p = 0.001), or p53 accumulation (HR:2.2, 95%CI:1.2-4.1, p = 0.02) and in patients receiving adjuvant chemoradiotherapy (HR:1.9, 95%CI:1.2-3.0, p = 0.005). Cells with reduced RAD21 expression exhibited enhanced sensitivity to 5-FU, alone or with Oxaliplatin. Conclusions: RAD21 expression in CRC is associated to advanced disease stage and confers poorer overall prognosis and resistance to chemoradiotherapy. RAD21 expression is of prognostic significance in tumours with somatic KRAS mutations or p53 accumulation. In these subgroups, RAD21 may be a novel important therapeutic target.

A multisite blinded study for the detection of BRAF mutations in formalin-fixed, paraffin-embedded malignant melanoma

Melanoma patients with BRAF mutations respond to treatment with vemurafenib, thus creating a need for accurate testing of BRAF mutation status. We carried out a blinded study to evaluate various BRAF mutation testing methodologies in the clinical setting. Formalin-fixed, paraffin-embedded melanoma samples were macrodissected before screening for mutations using Sanger sequencing, single-strand conformation analysis (SSCA), high resolution melting analysis (HRM) and competitive allele-specific TaqMan® PCR (CAST-PCR). Concordance of 100% was observed between the Sanger sequencing, SSCA and HRM techniques. CAST-PCR gave rapid and accurate results for the common V600E and V600K mutations, however additional assays are required to detect rarer BRAF mutation types found in 3–4% of melanomas. HRM and SSCA followed by Sanger sequencing are effective two-step strategies for the detection of BRAF mutations in the clinical setting. CAST-PCR was useful for samples with low tumour purity and may also be a cost-effective and robust method for routine diagnostics.

The G-protein-coupled receptor CLR is upregulated in an autocrine loop with adrenomedullin in clear cell renal cell carcinoma and associated with poor prognosis

PURPOSE

The G-protein-coupled receptor (GPCR) calcitonin receptor-like receptor (CLR) and its ligand peptide adrenomedullin (encoded by ADM gene) are implicated in tumor angiogenesis in mouse models but poorly defined in human cancers. We therefore investigated the diagnostic/prognostic use for CLR in human tumor types that may rely on adrenomedullin signaling and in clear cell renal cell carcinoma (RCC), a highly vascular tumor, in particular.

EXPERIMENTAL DESIGN

In silico gene expression mRNA profiling microarray study (n = 168 tumors) and cancer profiling cDNA array hybridization (n = 241 pairs of patient-matched tumor/normal tissue samples) were carried out to analyze ADM mRNA expression in 13 tumor types. Immunohistochemistry on tissue microarrays containing patient-matched renal tumor/normal tissues (n = 87 pairs) was conducted to study CLR expression and its association with clinicopathologic parameters and disease outcome.

RESULTS

ADM expression was significantly upregulated only in RCC and endometrial adenocarcinoma compared with normal tissue counterparts (P < 0.01). CLR was localized in tumor cells and vessels in RCC and upregulated as compared with patient-matched normal control kidney (P < 0.001). Higher CLR expression was found in advanced stages (P < 0.05), correlated with high tumor grade (P < 0.01) and conferred shorter overall survival (P < 0.01).

CONCLUSIONS

In human tissues ADM expression is upregulated in cancer type-specific manner, implicating potential role for adrenomedullin signaling in particular in RCC, where CLR localization suggests autocrine/paracrine mode for adrenomedullin action within the tumor microenvironment. Our findings reveal previously unrecognized CLR upregulation in an autocrine loop with adrenomedullin in RCC with potential application for this GPCR as a target for future functional studies and drug development.

DNA methylation in ductal carcinoma in situ of the breast

Ductal carcinoma in situ (DCIS) is a non-obligate precursor lesion of invasive carcinoma of the breast. Current prognostic markers based on histopathological examination are unable to accurately predict which DCIS cases will progress to invasive carcinoma or recur after surgical excision. Epigenetic changes have been shown to be a significant driver of tumorigenesis, and DNA methylation of specific gene promoters provides predictive and prognostic markers in many types of cancer, including invasive breast cancer. In general, the spectrum of genes that are methylated in DCIS strongly resembles that seen in invasive ductal carcinoma. The identification of specific prognostic markers in DCIS remains elusive and awaits additional work investigating a large panel of methylatable genes by using sensitive and reproducible technologies. This review critically appraises the role of methylation in DCIS and its use as a biomarker.

Triple negative breast cancers have a reduced expression of DNA repair genes

DNA repair is a key determinant in the cellular response to therapy and tumor repair status could play an important role in tailoring patient therapy. Our goal was to evaluate the mRNA of 13 genes involved in different DNA repair pathways (base excision, nucleotide excision, homologous recombination, and Fanconi anemia) in paraffin embedded samples of triple negative breast cancer (TNBC) compared to luminal A breast cancer (LABC). Most of the genes involved in nucleotide excision repair and Fanconi Anemia pathways, and CHK1 gene were significantly less expressed in TNBC than in LABC. PARP1 levels were higher in TNBC than in LABC. In univariate analysis high level of FANCA correlated with an increased overall survival and event free survival in TNBC; however multivariate analyses using Cox regression did not confirm FANCA as independent prognostic factor. These data support the evidence that TNBCs compared to LABCs harbour DNA repair defects.

Abstract 4693: Characterization of the differential mechanisms of CDKN2A inactivation in oral tongue squamous cell carcinomas and correlation with patient outcome

Background. CDKN2A inactivation has been reported to be a frequent event in head and neck squamous cell carcinomas that correlates with worse patient outcome. The differential mechanisms of CDKN2A inactivation in oral tongue squamous cell carcinomas (OTSCC) have been poorly characterised. We sought to determine the frequency of potential mechanisms of CDKN2A inactivation in OTSCC and explore their impact on patient outcome.

Material and methods. We investigated a cohort of 134 OTSCC patients treated between 2002 to 2008 with combinations of surgery, radiotherapy and chemotherapy, who have been comprehensively annotated for patient/tumour characteristics and outcome. 134 formalin fixed paraffin embedded blocks representative of primary tumours prior to treatment were collected. DNA was extracted from 115 patient blocks and a tissue microarray was made representing 123 patient samples. We assessed p16/CDKN2A expression by immunohistochemistry (IHC), promoter methylation status by methylation-sensitive high resolution melting, mutation status by Sanger sequencing, gene copy number variation by fluorescence in-situ hybridisation and correlated each of these with patient outcome.

Results. The majority of OTSCC demonstrated loss of p16 expression (107/118, 90.7%), assessed by IHC. The frequency of CDKN2A inactivating mutations was 20.3% (21/103), homozygous CDKN2A loss was 4.1% (7/98), hemizygous CDKN2A loss 30.6% (30/98), and CDKN2A promoter methylation &gt;10% was 17.7% (20/113). 34/107(31.8%) p16 IHC negative tumours had no evidence of CDKN2A mutation, copy number variation or promoter methylation identified. Of eleven p16 IHC positive patients, only two demonstrated evidence of HPV type 16 and 33 on PCR. No correlation was identified between any of the mechanisms of CDKN2A inactivation and clinicopathological features. Smoking status and age did not influence the frequency of any mechanism of CDKN2A inactivation or patient outcome. There was a non-significant trend for worse outcome for p16 IHC negative patients versus IHC positive patients (HR=0.65, 95% CI=0.23-1.79, p=0.40). No significant relationship between mechanisms of p16 inactivation and patient outcome were found.

Conclusion. Loss of p16 is a frequent event in oral tongue squamous cell carcinomas that can occur through gene copy number variation, mutation, promoter methylation or through other unidentified mechanisms. We identified no correlation between mechanisms of p16 loss and clinicopathological characteristics or patient outcome.

Citation Format: Annette M. Lim, Hongdo Do, Richard J. Young, Stephen Q. Wong, Christopher Angel, Marnie Collins, Elena Takano, June Corry, Stephen B. Fox, David Wiesenfeld, Stephen Kleid, Elizabeth Sigston, Bernard Lyon, Danny Rischin, Alexander Dobrovic, Benjamin Solomon. Characterization of the differential mechanisms of CDKN2A inactivation in oral tongue squamous cell carcinomas and correlation with patient outcome. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 4693. doi:10.1158/1538-7445.AM2013-4693

Increased pathological complete response rate after a long-term neoadjuvant letrozole treatment in postmenopausal oestrogen and/or progesterone receptor-positive breast cancer

Background:

The objective of this study was to determine the optimal scheduling of 2.5 mg daily letrozole in neoadjuvant breast cancer patients to obtain pathological complete response (pathCR) and assess Ki-67 expression as an early predictor of response.

Patients and methods:

This single institution study comprised 120 oestrogen receptor (ER)-positive postmenopausal women with primary breast cancer (clinical stage ⩾T2, N0–1), from three sequential cohorts (cohort A of 40, cohort B of 40 and cohort C of 40 patients, respectively) based on different duration of the neoadjuvant letrozole. Biological markers such as ER, progesterone receptor, HER2 and Ki-67 expression were tested at diagnosis and at definitive surgery.

Results:

A total of 89 patients (75.4%) achieved an objective response with 44 (37.3%) clinical CRs and 45 (38.1%) partial responses. The clinical CRs were significantly observed in cohort C (23 out of 40 patients, 57.5%) and B (16 out of 38 patients, 42.1%) compared with cohort A (5 out of 40 patients, 12.5%) (P-value for trend <0.001). Letrozole induced a similar significant reduction in Ki-67 index after treatment in all cohorts. The pathCR rate was significantly more frequent in cohort C (7 out of 40 patients, 17.5%) than in cohort A (1 out of 40 patients, 2.5%) and B (2 out of 40 patients, 5.0%) (P-value for trend <0.04).

Conclusion:

One-year neoadjuvant letrozole therapy leads to a higher pathCR rate and may be the optimal length of drug exposure.

HIF-1α stimulates aromatase expression driven by prostaglandin E2 in breast adipose stroma

INTRODUCTION

The majority of postmenopausal breast cancers are estrogen-dependent. Tumor-derived factors, such as prostaglandin E2 (PGE2), stimulate CREB1 binding to cAMP response elements (CREs) on aromatase promoter II (PII), leading to the increased expression of aromatase and biosynthesis of estrogens within human breast adipose stromal cells (ASCs). Hypoxia inducible factor-1α (HIF-1α), a key mediator of cellular adaptation to low oxygen levels, is emerging as a novel prognostic marker in breast cancer. We have identified the presence of a consensus HIF-1α binding motif overlapping with the proximal CRE of aromatase PII. However, the regulation of aromatase expression by HIF-1α in breast cancer has not been characterized. This study aimed to characterize the role of HIF-1α in the activation of aromatase PII.

METHODS

HIF-1α expression and localization were examined in human breast ASCs using quantitative PCR (QPCR), Western blotting, immunofluorescence and high content screening. QPCR and tritiated water-release assays were performed to assess the effect of HIF-1α on aromatase expression and activity. Reporter assays and chromatin immunoprecipitation (ChIP) were performed to assess the effect of HIF-1α on PII activity and binding. Treatments included PGE2 or DMOG ((dimethyloxalglycine), HIF-1α stabilizer). Double immunohistochemistry for HIF-1α and aromatase was performed on tissues obtained from breast cancer and cancer-free patients.

RESULTS

Results indicate that PGE2 increases HIF-1α transcript and protein expression, nuclear localization and binding to aromatase PII in human breast ASCs. Results also demonstrate that HIF-1α significantly increases PII activity, and aromatase transcript expression and activity, in the presence of DMOG and/or PGE2, and that HIF-1α and CREB1 act co-operatively on PII. There is a significant increase in HIF-1α positive ASCs in breast cancer patients compared to cancer-free women, and a positive association between HIF-1α and aromatase expression.

CONCLUSIONS

This study is the first to identify HIF-1α as a modulator of PII-driven aromatase expression in human breast tumor-associated stroma and provides a novel mechanism for estrogen regulation in obesity-related, post-menopausal breast cancer. Together with our on-going studies on the role of AMP-activated protein kinase (AMPK) in the regulation of breast aromatase, this work provides another link between disregulated metabolism and breast cancer.

PIK3CA mutations are frequently observed in BRCAX but not BRCA2-associated male breast cancer

INTRODUCTION

Although a substantial proportion of male breast cancers (MBCs) are hereditary, the molecular pathways that are activated are unknown. We therefore examined the frequency and clinicopathological associations of the PIK3CA/mammalian target of rapamycin (mTOR) and mitogen-activated protein kinase (MAPK) pathways and their regulatory genes in familial MBC.

METHODS

High resolution melting analysis and confirmatory sequencing was used to determine the presence of somatic mutations in PIK3CA (exon 9 and 20), AKT1 (exon 4), KRAS (exon 2) and BRAF (exon 15) genes in 57 familial MBCs. Further analysis of the PIK3CA/mTOR pathway was performed using immunohistochemistry for the pAKT1, pS6 and p4EBP1 biomarkers.

RESULTS

PIK3CA somatic mutations were identified in 10.5% (6 of 57) of cases; there were no AKT1, KRAS or BRAF somatic mutations. PIK3CA mutations were significantly more frequent in cancers from BRCAX patients (17.2%, 5/29) than BRCA2 (0%, 0/25) carriers (P = 0.030). Two BRCAX patients had an E547K mutation which has only been reported in one female breast cancer previously. PIK3CA mutation was significantly correlated with positive pS6 (83.3% vs. 32.0%, P = 0.024) and negative p4EBP1 (100% vs. 38.0%, P = 0.006) expression, but not pAKT expression. Expression of nuclear p4EBP1 correlated with BRCA2 mutation carrier status (68.0% vs. 38.7%, P = 0.035).

CONCLUSIONS

Somatic PIK3CA mutation is present in familial male breast cancer but absent in BRCA2 carriers. The presence of two of the extremely rare E547K PIK3CA mutations in our cohort may have specific relevance in MBCs. Further study of PIK3CA in MBCs, and in particular BRCAX patients, may contribute to further establishing the relevance of specific PIK3CA mutations in MBC aetiology and in the identification of particular patient groups most likely to benefit from therapeutic targeting with the novel PIK3CA inhibitors that are currently in development.

Genotypic and phenotypic analysis of familial male breast cancer shows under representation of the HER2 and basal subtypes in BRCA-associated carcinomas

Background

Male breast cancer (MBC) is an uncommon and relatively uncharacterised disease accounting for <1% of all breast cancers. A significant proportion occurs in families with a history of breast cancer and in particular those carrying BRCA2 mutations. Here we describe clinicopathological features and genomic BRCA1 and BRCA2 mutation status in a large cohort of familial MBCs.

Methods

Cases (n=60) included 3 BRCA1 and 25 BRCA2 mutation carries, and 32 non-BRCA1/2 (BRCAX) carriers with strong family histories of breast cancer. The cohort was examined with respect to mutation status, clinicopathological parameters including TNM staging, grade, histological subtype and intrinsic phenotype.

Results

Compared to the general population, MBC incidence was higher in all subgroups. In contrast to female breast cancer (FBC) there was greater representation of BRCA2 tumours (41.7% vs 8.3%, p=0.0008) and underrepresentation of BRCA1 tumours (5.0% vs 14.4%, p=0.0001). There was no correlation between mutation status and age of onset, disease specific survival (DSS) or other clincopathological factors. Comparison with sporadic MBC studies showed similar clinicopathological features. Prognostic variables affecting DSS included primary tumour size (p=0.003, HR:4.26 95%CI 1.63-11.11), age (p=0.002, HR:4.09 95%CI 1.65-10.12), lymphovascular (p=0.019, HR:3.25 95%CI 1.21-8.74) and perineural invasion (p=0.027, HR:2.82 95%CI 1.13-7.06). Unlike familial FBC, the histological subtypes seen in familial MBC were more similar to those seen in sporadic MBC with 46 (76.7%) pure invasive ductal carcinoma of no special type (IDC-NST), 2 (3.3%) invasive lobular carcinomas and 4 (6.7%) invasive papillary carcinoma. A further 8 (13.3%) IDC-NST had foci of micropapillary differentiation, with a strong trend for co-occurrence in BRCA2 carriers (p=0.058). Most tumours were of the luminal phenotype (89.7%), with infrequent HER2 (8.6%) and basal (1.7%) phenotype tumours seen.

Conclusion

MBC in BRCA1/2 carriers and BRCAX families is different to females. Unlike FBC, a clear BRCA1 phenotype is not seen but a possible BRCA2 phenotype of micropapillary histological subtype is suggested. Comparison with sporadic MBCs shows this to be a high-risk population making further recruitment and investigation of this cohort of value in further understanding these uncommon tumours.

Microscopic assessment of angiogenesis in tumors

Although it has been recognized for many centuries that neoplastic tissue is more vascular than its normal counterpart, it is only since Folkmans' hypothesis on antiangiogenesis (1) that a more quantitative method for measuring angiogenesis in tissue sections has been pursued. Folkman and colleagues recognized that quantitation of the tumor vasculature might play an important a role in predicting tumor behavior and patient management. They therefore developed a microscopic angiogenesis grading system, designated the "MAGS" score, calculated by measuring vessel number, endothelial cell hyperplasia, and cytology in tinctorially stained tissue sections (2). It was hoped that this would be an objective method for quantifying tumor angiogenesis, one that would yield important information on the relationship to other clinicopathological tumor characteristics and help in the testing of antiangiogenic therapies. However, although it was possible to classify tumors into endothelial "poor" or "rich," the technical limitations of sample selection, inter- and intra-observer variation, and conceptual biological problems were such that the technique could not be easily applied. Interest in grading tumor angiogenesis was rekindled in the 1980s with the advent of nonspecific endothelial markers (3-5), but only in the last five to ten years, with the advent of more specific endothelial markers, have quantitation studies on tissues have been performed.

Activity and safety of crizotinib in patients with ALK-positive non-small-cell lung cancer: updated results from a phase 1 study

BACKGROUND

ALK fusion genes occur in a subset of non-small-cell lung cancers (NSCLCs). We assessed the tolerability and activity of crizotinib in patients with NSCLC who were prospectively identified to have an ALK fusion within the first-in-man phase 1 crizotinib study.

METHODS

In this phase 1 study, patients with ALK-positive stage III or IV NSCLC received oral crizotinib 250 mg twice daily in 28-day cycles. Endpoints included tumour responses, duration of response, time to tumour response, progression-free survival (PFS), overall survival at 6 and 12 months, and determination of the safety and tolerability and characterisation of the plasma pharmacokinetic profile of crizotinib after oral administration. Responses were analysed in evaluable patients and PFS and safety were analysed in all patients. This study is registered with ClinicalTrials.gov, number NCT00585195.

FINDINGS

Between Aug 27, 2008, and June 1, 2011, 149 ALK-positive patients were enrolled, 143 of whom were included in the response-evaluable population. 87 of 143 patients had an objective response (60·8%, 95% CI 52·3-68·9), including three complete responses and 84 partial responses. Median time to first documented objective response was 7·9 weeks (range 2·1-39·6) and median duration of response was 49·1 weeks (95% CI 39·3-75·4). The response rate seemed to be largely independent of age, sex, performance status, or line of treatment. Median PFS was 9·7 months (95% CI 7·7-12·8). Median overall survival data are not yet mature, but estimated overall survival at 6 and 12 months was 87·9% (95% CI 81·3-92·3) and 74·8% (66·4-81·5), respectively. 39 patients continued to receive crizotinib for more than 2 weeks after progression because of perceived ongoing clinical benefit from the drug (12 for at least 6 months from the time of their initial investigator-defined disease progression). Overall, 144 (97%) of 149 patients experienced treatment-related adverse events, which were mostly grade 1 or 2. The most common adverse events were visual effects, nausea, diarrhoea, constipation, vomiting, and peripheral oedema. The most common treatment-related grade 3 or 4 adverse events were neutropenia (n=9), raised alanine aminotransferase (n=6), hypophosphataemia (n=6), and lymphopenia (n=6).

INTERPRETATION

Crizotinib is well tolerated with rapid, durable responses in patients with ALK-positive NSCLC. There seems to be potential for ongoing benefit after initial disease progression in this population, but a more formal definition of ongoing benefit in this context is needed.

Assessing HER2 amplification in breast cancer: findings from the Australian In Situ Hybridization Program

In August 2006, the Australian government approved subsidized trastuzumab therapy for human epidermal growth factor receptor 2 (HER2)-positive early breast cancer, and it was mandated that HER2 testing should be performed using in situ hybridization (ISH) rather than immunohistochemistry (IHC). Here we review results of the first regulated, nationwide program to provide HER2 ISH testing for all newly diagnosed breast cancer patients, with a particular emphasis on cases where IHC and ISH results were discordant. Data from all laboratories participating in the program were collated. Cases with an equivocal ISH test result [by chromogenic ISH (CISH) or silver ISH (SISH)] were tested centrally by fluorescence ISH. Most laboratories also performed HER2 IHC, and 200 cases with discordant IHC and ISH results were selected for further analysis in a central laboratory. A total of 26 laboratories were involved and 53,402 tests were reported. Over a 4-year period the HER2 positivity rate decreased for primary cancers from 23.8 to 14.6 %, but remained relatively constant for samples from metastases. Average ISH reporting times were <5 days for all yearly reporting periods. Test-repeat rates decreased for CISH (8.9-3.6 %) and SISH (13.7-8.4 %). Only 12 of 196 cases remained discordant after retesting in a central laboratory. These findings demonstrate the successful implementation of a regulated, national program that continues to collect data on HER2 status. The results also highlight the differences in IHC interpretation between local laboratories and a central, more experienced, laboratory. This model could be used to establish future biomarker-testing programs in other countries.

ANZ1001 SORBET: Study of estrogen receptor beta and efficacy of tamoxifen, a single arm, phase II study of the efficacy of tamoxifen in triple-negative but estrogen receptor beta-positive metastatic breast cancer

TPS1136

Background: Targeted therapies are needed for triple negative breast cancer (BC). ERβ is expressed in at least 20% of triple negative BCs.  ERβ binds estrogen and tamoxifen with a similar affinity to ERα.  ERβ has 5 isoforms but only ERβ1 is fully functional. ERβ expression has been shown to be significantly associated with improved distant disease free survival and better overall survival in tamoxifen treated ERα negative patients in retrospective studies.  This “proof of principle” study will determine the efficacy of tamoxifen in patients with triple negative but ERβ positive metastatic BC. Methods: This single arm phase II study, being conducted by the Australia and New Zealand Breast Cancer Trials Group, has a Simon's 2 stage optimal design. The primary end-point is objective response rate (complete and partial responses).  Progression free survival and clinical benefit rate will also be assessed. Eligibility criteria include histologically or cytologically confirmed metastatic triple negative BC (ER and PR absent, HER2 ISH negative or IHC 0 or 1) and measureable disease as per RECIST 1.1.  Consenting patients undergo central ERβ testing and confirmation of triple negative status on a metastatic biopsy sample. ERβ positive patients (ERβ1 nuclear staining with Allred score >4) are offered trial participation. To date 12 potentially eligible patients have been screened for ERβ; 4 had Allred score >4 (although 2 of these subsequently proved to be ineligible for the trial), 7 had Allred scores <4 and 1 result is pending. Consenting patients receive tamoxifen 20mg per oral daily until disease progression, unacceptable toxicity or withdrawal of consent. If there are ≥2 responses in the first stage of 28 patients, an additional 38 patients will be accrued. Tamoxifen will be considered worthy of further research if there are ≥6 responses in the total 66 patients recruited. Current accrual is 1. Registered on ANZCTR (12610000506099).

Clinical significance of genomic alterations of the CDK4-pathway and sensitivity to the CDK4 inhibitor PD 0332991 in melanoma

8520

Background: Activation of CDK4 by amplification, increased expression of Cyclin D1 (CCND1) or reduced expression of the CDK inhibitor p16 (CDKN2A) can contribute to transformation of melanocytes indicating that CDK4 can act as an oncogene in melanoma.To explore if CDK4 may be a viable target for the treatment of human melanoma we have analyzed the frequency and clinico-pathological associations of genomic alterations of the CDK4 pathway in primary human melanoma and examined the genomic predictors of sensitivity to the highly selective CDK4/6 inhibitor PD 0332991 (991) in a panel of melanoma cell lines. Methods: A series of 167 primary melanomas with clinical, molecular and pathological annotation, including median follow up of 6.6 years, were analyzed for copy number variation (CNV)- gain of CDK4 or CCND1 (average gene copy >2.4) or loss of CDKN2A (average gene copy <1.4), by fluorescence in situ hybridization. A panel of 39 cell lines were treated with 991 in vitro and GI50s calculated. The mean GI50 of the melanoma cell lines was used to define sensitivity. Gene expression profiling and mutation or CNV in CDKN2A were used to identify predictors of sensitivity. Results: 75% of primary melanomas had at least one CNV (75%, 70% and 82% for BRAF, NRAS or wild-type BRAF/NRAS mutation status respectively). 55% showed loss of CDKN2A. 28% of melanomas had two or more CNVs. Melanomas with two or more CNVs involving CCND1 had worse overall survival (HR 5.56, p=0.02). Low CDKN2A mRNA expression or mutation or loss of CDKN2A predicted sensitivity to 991 with 30/33 mutant/loss lines being sensitive compared to only 2/6 wild type lines (p<0.006). Expression of CDK4, CCND1 or other cyclins or CDK-inhibitors did not predict sensitivity to 991. Conclusions: Genomic alterations in the CDK4 pathway are frequent in melanoma and are associated with worse survival, particularly when melanomas harbor two or more CNVs involving CCND1. Mutation, loss or low expression of CDKN2A in melanoma cell lines predicted sensitivity to the CDK4 inhibitor 991. Taken together these data support evaluation of CDK4 inhibitors in melanoma and suggest that CDKN2A maybe a genomic predictor of sensitivity to these agents.

Gastric HER2 Testing Study (GaTHER): an evaluation of gastric/gastroesophageal junction cancer testing accuracy in Australia

Trastuzumab provides a survival benefit in patients with human epidermal growth factor receptor 2 (HER2)-amplified/overexpressed advanced gastric and gastroesophageal junction cancers (GC/GJCs). However, the optimal method for testing is unclear. The aim of this study was to assess interlaboratory agreement on HER2 scoring in GC/GJC to aid the development of a robust testing algorithm for diagnostic practice in Australia. Nine laboratories assessed the HER2 status of 100 GC/GJC tissue samples by immunohistochemistry (IHC) and in situ hybridization (ISH) [chromogenic (CISH) or silver (SISH)] using both HER2 copy number and HER2:chr17 (chromosome 17) ratio. Results were compared with reference fluorescence ISH (FISH). Interlaboratory agreement on IHC3+ scoring was good (κ=0.76), and there was good/very good agreement between IHC (positivity defined as IHC3+) and ISH when HER2 copy number was used (κ=0.72 to 0.87). Agreement on CISH/SISH scoring was good/very good when HER2 copy number was used (κ=0.68 to 0.86), and agreement between CISH/SISH and FISH using HER2 copy number was very good (κ=0.88 to 0.91). Agreement was reduced when HER2:chr17 ratio was used. The good agreement for HER2 copy number determined by bright-field ISH suggests that this is the optimal method for testing in GC/GJC cases. An IHC3+ score was strongly predictive of a positive ISH result, although agreement for all IHC scores was only moderate, suggesting that IHC triage before ISH testing would be the most cost-effective strategy. However, because of the unique features of GC/GJC samples and the difficulty of ensuring consistent HER2 staining in the community setting, it is recommended that HER2 status in advanced GC/GJC be determined by both IHC and ISH in the same laboratory.

Enhanced RAD21 cohesin expression confers poor prognosis in BRCA2 and BRCAX, but not BRCA1 familial breast cancers

INTRODUCTION

The RAD21 gene encodes a key component of the cohesin complex, which is essential for chromosome segregation, and together with BRCA1 and BRCA2, for high-fidelity DNA repair by homologous recombination. Although its expression correlates with early relapse and treatment resistance in sporadic breast cancers, it is unclear whether familial breast cancers behave in a similar manner.

METHODS

We performed an immunohistochemical analysis of RAD21 expression in a cohort of 94 familial breast cancers (28 BRCA1, 27 BRCA2, and 39 BRCAX) and correlated these data with genotype and clinicopathologic parameters, including survival. In these cancers, we also correlated RAD21 expression with genomic expression profiling and gene copy-number changes and miRNAs predicted to target RAD21.

RESULTS

No significant differences in nuclear RAD21 expression were observed between BRCA1 (12 (43%) of 28), BRCA2 (12 (44%) of 27), and BRCAX cancers (12 (33%) of 39 (p = 0.598). No correlation was found between RAD21 expression and grade, size, or lymph node, ER, or HER2 status (all P > 0.05). As for sporadic breast cancers, RAD21 expression correlated with shorter survival in grade 3 (P = 0.009) and but not in grade 1 (P = 0.065) or 2 cancers (P = 0.090). Expression of RAD21 correlated with poorer survival in patients treated with chemotherapy (P = 0.036) but not with hormonal therapy (P = 0.881). RAD21 expression correlated with shorter survival in BRCA2 (P = 0.006) and BRCAX (P = 0.008), but not BRCA1 cancers (P = 0.713). Changes in RAD21 mRNA were reflected by genomic changes in DNA copy number (P < 0.001) and by RAD21 protein expression, as assessed with immunohistochemistry (P = 0.047). High RAD21 expression was associated with genomic instability, as assessed by the total number of base pairs affected by genomic change (P = 0.048). Of 15 miRNAs predicted to target RAD21, mir-299-5p inversely correlated with RAD21 expression (P = 0.002).

CONCLUSIONS

Potential use of RAD21 as a predictive and prognostic marker in familial breast cancers is hence feasible and may therefore take into account the patient's BRCA1/2 mutation status.

Positron emission tomography and neoadjuvant therapy of breast cancer

The increasing use of neoadjuvant therapy for breast cancer has led to the development of early surrogate markers of response. Positron emission tomography (PET) allows noninvasive study of fundamental biologic processes in the tumor; furthermore, PET provides various markers to assess tumor response early in the course of therapy. Numerous studies have shown that changes in tumor glucose metabolism during therapy are significantly correlated with final response and patient outcome. Moreover, new PET tracers that are currently being developed or under evaluation, providing specific information on tumor characteristics or receptor expression, will assist the development of new targeted anticancer agents.

Molecular oncology and the neoadjuvant setting: the perfect blend for treatment personalization and clinical trial design

Breast cancer is a heterogeneous disease. Predictive molecular markers are crucial in patient management, but the only recommended predictive biomarkers are estrogen and progesterone receptors and HER2. There are many new targeted therapies, and although the target pathway expression is readily analyzed on conventional pathology, the dynamic response cannot be assessed and pathway expression is no guarantee it has a major driver role, even if mutated. Selecting therapies requires considering the patient, the molecular characteristics of the tumor, and the microenvironment of the tumor. Thus, the integration of molecular pathology, imaging, and early tumor biological response to therapy may provide evidence of drug activity and allow more rapid changes of therapy. The adaptive response of the tumor is a key resistance mechanism that can be assessed readily in the neoadjuvant setting. Although there are no markers that meet all surrogacy criteria, their use could provide crucial information on mechanisms of drug sensitivity/resistance. Validation of such markers requires a major emphasis on neoadjuvant trials to relate early-biomarker response to outcome.

Predictive immunohistochemical biomarkers in the context of neoadjuvant therapy for breast cancer

The adoption of personalized medicine has led to the search for prognostic and predictive markers that can be applied to individual patients to give optimal information for their clinical management. We have used samples from randomized clinical trials of hormonal and chemotherapy to identify relevant markers of sensitivity and resistance using a neoadjuvant approach by linking expression of a panel of proteins involved in growth factor receptor signaling, angiogenesis, estrogen receptor signaling, and hypoxia to individual patient response. We evaluated samples from randomized clinical trials of epirubicin with or without tamoxifen, and letrozole with or without metronomic cyclophosphamide, to study chemotherapy, hormonal therapy, and antiangiogenic effects. We present a proof of principle of this approach in identifying several key pathways that are associated with clinical and pathological response. Thus, we have shown that the hypoxia-inducible factor (HIF) pathway, mitogen activated protein kinase, and phosphorylated estrogen receptor-α can identify patients who are likely to respond to hormonal therapy and that HIF signaling is also a marker of resistance for anthracycline-based chemotherapy. To redress the role of HIF, we then evaluated samples from a randomized control trial of an anthracycline chemotherapy with and without erythropoietin. These studies demonstrate that the approach of using primary systemic therapy in breast can identify markers of response and potentially targets for rationale design of new therapies.