Michel van Kruchten

PET imaging of oestrogen receptors in patients with breast cancer

Oestrogen receptors are overexpressed in around 70% of all breast cancers, and are a target for endocrine therapy. These receptors can be visualised on PET with use of 16α-[(18)F]-fluoro-17β-oestradiol ((18)F-FES) as a tracer. Compared with biopsy, which enables assessment of individual sites, whole-body (18)F-FES-PET enables quantification of oestrogen-receptor expression in all metastases. In several studies, measurement of tumour protein expression in oestrogen receptors by (18)F-FES-PET, concurrent with biopsy, detected oestrogen-receptor-positive tumour lesions with a sensitivity of 84% and specificity of 98%. Roughly 45% of patients with metastatic breast cancer have discordant oestrogen-receptor expression across lesions (ie, (18)F-FES-positive and (18)F-FES-negative metastases). Low tumour (18)F-FES uptake in metastases can predict failure of hormonal therapy in patients with oestrogen-receptor-positive primary tumours. Finally, (18)F-FES-PET has shown that oestrogen-receptor binding capacity changes after intervention with hormonal drugs, but findings need to be confirmed. Factors other than oestrogen-receptor expression, including menopausal status and concomitant therapies, that can affect tumour (18)F-FES uptake must be taken into account.

PET Imaging of Estrogen Receptors as a Diagnostic Tool for Breast Cancer Patients Presenting with a Clinical Dilemma

16α-18F-fluoro-17β-estradiol (18F-FES) is an estrogen receptor (ER)–specific PET tracer with various potential interesting applications. The precise contribution of this technique in current clinical practice, however, has yet to be determined. Therefore, the aim of this study was to evaluate the value of 18F-FES PET in breast cancer patients presenting with a clinical dilemma. Methods: 18F-FES PET examination could be requested by referring physicians for patients with a history of ER-positive breast cancer and the presence of a clinical dilemma despite complete standard work-up. All requests for 18F-FES PET required a positive arbitration by a dedicated medical oncologist and nuclear medicine physician. The referring physician was asked to fill in validated questionnaires before, shortly after, and at more than 3 mo after 18F-FES PET to determine indication, diagnostic value, and therapeutic consequences of 18F-FES PET. To further validate 18F-FES PET findings, 18F-FES PET lesions were quantified and compared with centrally reviewed conventional imaging. Results: Thirty-three patients underwent 18F-FES PET between December 2008 and October 2010. 18F-FES PET was requested to evaluate equivocal lesions on conventional work-up (n = 21), ER status in metastatic patients (n = 10), and the origin of metastases (n = 2). 18F-FES–positive lesions were observed in 22 patients. 18F-FES PET was especially sensitive for bone metastases, detecting 341 bone lesions, compared with 246 by conventional imaging. The sensitivity for liver metastases was poor, and quantification of 18F-FES uptake in liver lesions was hampered by high physiologic background. 18F-FES uptake was highly variable between all metastases (range of standardized uptake value, 1.20–18.81), and 45% of the patients with a positive 18F-FES PET finding had both 18F-FES–positive and 18F-FES–negative metastases. 18F-FES PET improved diagnostic understanding in 88% of the patients and led to therapy change in 48% of the patients. Conclusion: With the exception of liver metastases, whole-body imaging of ER expression with 18F-FES PET can be a valuable additional diagnostic tool when standard work-up is inconclusive. 18F-FES PET supported therapy decisions by improving diagnostic understanding and providing information on ER status of tumor lesions.

Measuring residual estrogen receptor availability during fulvestrant therapy in patients with metastatic breast cancer

UNLABELLED It is unknown whether the current dose of fulvestrant, an estrogen receptor (ER) antagonist, is sufficient for maximal ER downregulation in patients with metastatic breast cancer. We performed a feasibility study to assess ER availability before and during fulvestrant. Sixteen patients with ER-positive metastatic breast cancer underwent positron emission tomography/computed tomography (PET/CT) at baseline (scan 1), day 28 (scan 2), and day 84 (scan 3) to monitor tumor [(18)F]fluoroestradiol (FES) uptake. Incomplete reduction in ER availability was predefined as <75% decrease in median tumor FES uptake and a residual standardized uptake value (SUVmax) of ≥1.5. In total, 131 FES-positive lesions were identified (median SUVmax of 2.9; range, 1.7-6.5). The median change in patients during fulvestrant treatment was -85% at scan 2, but varied widely (-99% to +60%). Fulvestrant reduced tumor FES uptake incompletely at scan 2 in 6 (38%) of the 16 patients, which was associated with early progression. SIGNIFICANCE Serial imaging of tumor estrogen uptake by FES-PET can give insight into the dose needed for ER antagonists to completely abolish ER. FES-PET showed significant residual ER availability in tumors during fulvestrant therapy in 38% of patients, which was associated with early progression.

Current and upcoming approaches to exploit the reversibility of epigenetic mutations in breast cancer

DNA methylation and histone modifications are important epigenetic modifications associated with gene (dys)regulation. The epigenetic modifications are balanced by epigenetic enzymes, so-called writers and erasers, such as DNA (de)methylases and histone (de)acetylases. Aberrant epigenetic alterations have been associated with various diseases, including breast cancer. Since aberrant epigenetic modifications are potentially reversible, they might represent targets for breast cancer therapy. Indeed, several drugs have been designed to inhibit epigenetic enzymes (epi-drugs), thereby reversing epigenetic modifications. US Food and Drug Administration approval has been obtained for some epi-drugs for hematological malignancies. However, these drugs have had very modest anti-tumor efficacy in phase I and II clinical trials in breast cancer patients as monotherapy. Therefore, current clinical trials focus on the combination of epi-drugs with other therapies to enhance or restore the sensitivity to such therapies. This approach has yielded some promising results in early phase II trials. The disadvantage of epi-drugs, however, is genome-wide effects, which may cause unwanted upregulation of, for example, pro-metastatic genes. Development of gene-targeted epigenetic modifications (epigenetic editing) in breast cancer can provide a novel approach to prevent such unwanted events. In this context, identification of crucial epigenetic modifications regulating key genes in breast cancer is of critical importance. In this review, we first describe aberrant DNA methylation and histone modifications as two important classes of epigenetic mutations in breast cancer. Then we focus on the preclinical and clinical epigenetic-based therapies currently being explored for breast cancer. Finally, we describe epigenetic editing as a promising new approach for possible applications towards more targeted breast cancer treatment.

Hormone receptors as a marker of poor survival in epithelial ovarian cancer

OBJECTIVE Androgen receptor (AR), estrogen receptor α and β (ERα, ERβ), and progesterone receptor (PR) are potential therapeutic targets in epithelial ovarian cancer. In this study we evaluate the prognostic value of these hormone receptors in ovarian cancer patients. METHODS In a prospective multicenter randomized controlled phase II trial 196 ovarian cancer patients were randomized to carboplatin/docetaxel±celecoxib. Of 121 patients sufficient tumor tissue was available for hormone receptor analysis. Tissue micro-arrays were stained for AR, ERα, ERβ, and PR. Cluster analysis was performed to identify subgroups based on hormone receptor expression profile. Receptor expression was correlated to progression-free survival (PFS) and overall survival (OS) in uni- and multivariate analysis. RESULTS AR, ERα, ERβ, and PR were expressed in respectively 10%, 31%, 73%, and 19%. In patients with synchronous metastasis tissue available (n=69 patients), discordant receptor expression was observed in 9-32%. ERβ-expression was associated with poor PFS and OS (hazard ratios 1.88 and 1.92). Clustering analysis revealed a subgroup with hormone receptor negative disease that had a favorable PFS and OS. CONCLUSION Hormone receptors are expressed in the majority of ovarian cancer tumors and may serve as therapeutic targets. Clustering analysis can reveal subgroups with different outcome, which may prove valuable in selecting patients for endocrine therapy.

Assessment of Estrogen Receptor Expression in Epithelial Ovarian Cancer Patients Using 16α-18F-Fluoro-17β-Estradiol PET/CT

The estrogen receptor α (ERα) is expressed in approximately 70% of ovarian cancer tumors. PET of tumor ERα expression with the tracer 16α-18F-fluoro-17β-estradiol (18F-FES) may be valuable to select ovarian cancer patients for endocrine therapy. The aim of this study was to evaluate the feasibility of 18F-FES PET to determine tumor ERα expression noninvasively in epithelial ovarian cancer patients. Methods: 18F-FES PET/CT was performed shortly before cytoreductive surgery. Tumor 18F-FES uptake was quantified for all lesions 10 mm or greater on CT and expressed as maximum standardized uptake value. 18F-FES PET/CT findings were compared with histology and immunohistochemistry for ERα, ERβ, and progesterone receptor. Receptor expression was scored semiquantitatively using H-scores (percentage of positive tumor cells × staining intensity). The optimum threshold to discriminate ER-positive and -negative lesions was determined by receiver-operating-characteristic analysis. Results: In the 15 included patients with suspected ovarian cancer, 32 measurable lesions greater than 10 mm were present on CT. Tumor 18F-FES uptake could be quantified for 28 lesions (88%), and 4 lesions were visible but nonquantifiable because of high uptake in adjacent tissue. During surgery, histology was obtained of 23 of 28 quantified lesions (82%). Quantitative 18F-FES uptake correlated with the semiquantitative immunoscore for ERα (ρ = 0.65, P < 0.01) and weakly with progesterone receptor expression (ρ = 0.46, P = 0.03) and was not associated with ERβ expression (ρ = 0.21, P = 0.33). The optimum threshold to discriminate ERα-positive and ERα-negative lesions was a maximum standardized uptake value greater than 1.8, which provided a 79% sensitivity, 100% specificity, and area under the curve of 0.86 (95% confidence interval, 0.70–1.00). In 2 of 7 patients with cytology/histology available at primary diagnosis and at debulking surgery, immunohistochemical ERα expression had changed over time. 18F-FES PET was in accordance with histology at debulking surgery but not at primary diagnosis, indicating that 18F-FES PET could provide reliable information about current tumor ERα status. Conclusion: 18F-FES PET/CT can reliably assess ERα status in epithelial ovarian cancer tumors and metastases noninvasively. Evaluation of the predictive value of 18F-FES PET/CT for endocrine therapy in epithelial ovarian cancer patients is warranted.

Molecular imaging for monitoring treatment response in breast cancer patients

Currently, tumour response following drug treatment is based on measurement of anatomical size changes. This is often done according to Response Evaluation Criteria in Solid Tumours (RECIST) and is generally performed every 2-3 cycles. Bone metastases, being the most common site of distant metastases in breast cancer, are not measurable by RECIST. The standard response measurement provides no insight in changes of molecular characteristics. In the era of targeted medicine, knowledge of specific molecular tumour characteristics becomes more important. A potential way to assess this is by means of molecular imaging. Molecular imaging can visualise general tumour processes, such as glucose metabolism with (18)F-fluorodeoxyglucose ((18)F-FDG) and DNA synthesis with (18)F-fluorodeoxythymidine ((18)F-FLT). In addition, an increasing number of more specific targets, such as hormone receptors, growth factor receptors, and growth factors can be visualised. In the future molecular imaging may thus be of value for personalised treatment-selection by providing insight in the expression of these drug targets. Additionally, when molecular changes can be detected early during therapy, this may serve as early predictor of response. However, in order to define clinical utility of this approach results from (ongoing) clinical trials is required. In this review we summarise the potential role of molecular imaging of general tumour processes as well as hormone receptors, growth factor receptors, and tumour micro-environment for predicting and monitoring treatment response in breast cancer patients.

Positron emission tomography imaging of oestrogen receptor-expression in endometrial stromal sarcoma supports oestrogen receptor-targeted therapy : Case report and review of the literature

Although the majority of endometrial stromal sarcomas (ESSs) express oestrogen receptor (ER), data on the efficacy of ER-targeted therapies are scarce. Using PubMed search engine we identified nine case reports and small series in a total of 25 patients reporting on the efficacy of palliative ER-targeted therapies. Literature supports the efficacy of aromatase inhibitors after the failure of progestins, but not of the partial ER-antagonist tamoxifen. Fulvestrant is a pure ER-antagonist with a distinct mechanism, of which efficacy has not yet been reported in ESS. We present a patient that underwent positron emission tomography and computed tomography (PET/CT) of ER-expression with the tracer (18)F-fluoroestradiol (FES). High levels of ER-expression provided a rationale for fulvestrant therapy. FES-PET/CT was repeated after 6 months and indicated a strong decrease in tumour FES-uptake, and 15% reduction in tumour diameters according to Response Evaluation Criteria in Solid Tumours (RECIST) criteria.

Androgen and Estrogen Receptor Imaging in Metastatic Breast Cancer Patients as a Surrogate for Tissue Biopsies

In addition to the well-known estrogen receptor (ER) and human epidermal growth factor receptor 2, the androgen receptor (AR) is also a potential drug target in breast cancer treatment. Whole-body imaging can provide information across lesions within a patient. ER expression in tumor lesions can be visualized by 18F-fluoroestradiol (18F-FES) PET, and AR expression has been visualized in prostate cancer patients with 18F-fluorodihydrotestosterone (18F-FDHT) PET. Our aim was to assess the concordance between 18F-FDHT and 18F-FES PET and tumor AR and ER expression measured immunohistochemically in patients with metastatic breast cancer. Methods: Patients with ER-positive metastatic breast cancer were eligible for the study, irrespective of tumor AR status. The concordance of 18F-FDHT and 18F-FES uptake on PET with immunohistochemical expression of AR and ER in biopsies of corresponding metastases was analyzed. Patients underwent 18F-FDHT PET and 18F-FES PET. A metastasis was biopsied within 8 wk of the PET procedures. Tumor samples with more than 10% and 1% nuclear tumor cell staining were considered, respectively, AR- and ER-positive. Correlations between PET uptake and semiquantitative immunohistochemical scoring (percentage positive cells × intensity) were calculated. The optimum threshold of SUV to discriminate positive and negative lesions for both AR and ER was determined by receiver-operating-characteristic analysis. Results: In the 13 evaluable patients, correlation (R2) between semiquantitative AR expression and 18F-FDHT uptake was 0.47 (P = 0.01) and between semiquantitative ER expression and 18F-FES uptake 0.78 (P = 0.01). The optimal cutoff for AR-positive lesions was an SUVmax of 1.94 for 18F-FDHT PET, yielding a sensitivity of 91% and a specificity of 100%; the optimal cutoff was an SUVmax of 1.54 for 18F-FES PET, resulting in a sensitivity and specificity of 100% for ER. Conclusion: 18F-FDHT and 18F-FES uptake correlate well with AR and ER expression levels in representative biopsies. These results show the potential use of whole-body imaging for receptor status assessment, particularly in view of biopsy-associated sampling errors and heterogeneous receptor expression in breast cancer metastases.

Abstract 4768: Frequency and prognostic value of hormone receptor expression in epithelial ovarian cancer.

Proceedings: AACR 104th Annual Meeting 2013; Apr 6-10, 2013; Washington, DC Introduction: Ovarian cancer (OC) is the second most common and most lethal gynecological cancer. High recurrence rate and poor prognosis underline the need to explore targeted therapies. Potential targets include hormone receptors (androgen receptor [AR], estrogen receptor α [ERα], estrogen receptor β [ERβ], and progesterone receptor [PR]). Clinical studies have shown modest effects of endocrine agents in phase II studies. Nevertheless, the role of hormones and their putative receptors in OC remains largely unknown. To further probe their role, tumor material for hormone receptor analysis was obtained from a group of patients who were treated in a prospective clinical trial. Methods: Between March 2003 and November 2008, 196 epithelial OC patients were included in a prospective multicenter randomized controlled phase II trial and assigned to carboplatin/docetaxel ± celecoxib. The majority (92.5%) of patients had high-stage disease. Histologic material for biomarker analysis was obtained from 121 patients. Histological subtypes were serous (70%), endometrioid (17%), clearcell (9%), and mucinous (4%). Mean PFS and OS were 16 and 32 months. Tissue micro arrays (4 cores/sample) were constructed and stained for AR, ERα, ERβ, and PR and scored semi-quantitatively by two independent observers. A cut-off of >10% positive staining was used to dichotomize results. Receptor expression was correlated to PFS and OS in uni- and multivariate analysis (including age, FIGO stage, grade, histological subtype, and residual disease after surgery). Results: Tumors were positive for AR, ERα, ERβ, and PR in 10%, 31%, 78%, and 21% of the cases. ERα-positivity was significantly correlated with ERβ-positivity (p = 0.021). Both ERα- and ERβ-positivity were significantly correlated with AR-positivity (p <0.001; p = 0.041). From 67 patients, also tissue of synchronous omental metastases was available. Gain of receptor expression was observed in 9-23% of the omental metastases compared to the primary tumor. Loss of receptor expression was observed in 9-19%. In multivariate analysis, ERβ staining of the primary tumor was associated with decreased PFS and OS (HR 1.85, p = 0.073; HR 2.15, p = 0.048). Conclusion: We showed that steroid receptors are present in a significant subpopulation of OC tumors and have prognostic value. Based on literature they can serve as potential targets for adjuvant and palliative endocrine therapy. Effects of endocrine therapy can probably be improved by taking into account heterogeneity of receptor expression. Evaluation of the predictive value of hormone receptor expression for response to endocrine therapy in OC therefore deserves further evaluation. Citation Format: Michel van Kruchten, Pauline W. van der Marel, Henriette J.G. Arts, Harry Hollema, Linda de Munck, Tineke van der Sluis, Hetty Timmer-Bosscha, Geke A.P. Hospers, An K.L. Reyners. Frequency and prognostic value of hormone receptor expression in epithelial ovarian cancer. [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 4768. doi:10.1158/1538-7445.AM2013-4768