Carolien P. Schröder

Intraoperative Near-Infrared Fluorescence Tumor Imaging with Vascular Endothelial Growth Factor and Human Epidermal Growth Factor Receptor 2 Targeting Antibodies

Fluorescence imaging is currently attracting much interest as a method for intraoperative tumor detection, but most current tracers lack tumor specificity. Therefore, this technique can be further improved by tumor-specific detection. With tumor-targeted antibodies bound to a radioactive label, tumor-specific SPECT or PET is feasible in the clinical setting. The aim of the present study was to apply antibody-based tumor detection to intraoperative optical imaging, using preclinical in vivo mouse models. Methods: Anti–vascular endothelial growth factor (VEGF) antibody bevacizumab and anti–human epidermal growth factor receptor (HER) 2 antibody trastuzumab were labeled with the near-infrared (NIR) fluorescence dye IRDye 800CW. Tumor uptake of the fluorescent tracers and their 89Zr-labeled radioactive counterparts for PET was determined in human xenograft–bearing athymic mice during 1 wk after tracer injection, followed by ex vivo biodistribution and pathologic examination. Intraoperative imaging of fluorescent VEGF- or HER2-positive tumor lesions was performed in subcutaneous tumors and in intraperitoneal dissemination tumor models. Results: Tumor-to-background ratios, with fluorescent imaging, were 1.93 ± 0.40 for bevacizumab and 2.92 ± 0.29 for trastuzumab on day 6 after tracer injection. Real-time intraoperative imaging detected tumor lesions at even the submillimeter level in intraperitoneal dissemination tumor models. These results were supported by standard histology, immunohistochemistry, and fluorescence microscopy analyses. Conclusion: NIR fluorescence–labeled antibodies targeting VEGF or HER2 can be used for highly specific and sensitive detection of tumor lesions in vivo. These preclinical findings encourage future clinical studies with NIR fluorescence–labeled tumor-specific antibodies for intraoperative-guided surgery in cancer patients.

89Zr-Bevacizumab PET of Early Antiangiogenic Tumor Response to Treatment with HSP90 Inhibitor NVP-AUY922

Angiogenesis is a critical step in tumor development, in which vascular endothelial growth factor (VEGF) is a key growth aspect. Heat shock protein 90 (HSP90), a molecular chaperone, is essential for the activity of key proteins involved in VEGF transcription. Currently, no biomarkers to predict the effect of, or monitor, HSP90 inhibition therapy in individual patients exist. 89Zr-bevacizumab PET provides a noninvasive tool to monitor tumor VEGF levels. The aim of this study was to investigate 89Zr-bevacizumab PET for early antiangiogenic tumor response evaluation of treatment with the new HSP90 inhibitor NVP-AUY922. In xenografts of A2780 and its cisplatin-resistant CP70 human ovarian cancer subline, 89Zr-bevacizumab small-animal PET was performed before and after NVP-AUY922 treatment and verified with histologic response and ex vivo tumor VEGF levels. Compared with pretreatment values, 2 wk of NVP-AUY922 treatment decreased 89Zr-bevacizumab uptake by 44.4% (P = 0.0003) in A2780 xenografts, whereas tumor uptake was not affected in CP70 xenografts. The same pattern was observed in A2780 and CP70 tumor VEGF levels, measured with enzyme-linked immunosorbent assay, and mean vessel density after NVP-AUY922 treatment. These findings coincided with reduction in the proliferation rate, assessed by Ki67 staining, in A2780 tumor tissue only. Conclusion: 89Zr-bevacizumab PET was in line with the antiangiogenic response and direct antitumor effects after NVP-AUY922 treatment, supporting the specificity of 89Zr-bevacizumab PET as a sensitive technique to monitor the antiangiogenic response of HSP90 inhibition in vivo.

89Zr-Bevacizumab PET Imaging in Primary Breast Cancer

Vascular endothelial growth factor (VEGF)-A is overexpressed in most malignant and premalignant breast lesions. VEGF-A can be visualized noninvasively with PET imaging and using the tracer 89Zr-labeled bevacizumab. In this clinical feasibility study, we assessed whether VEGF-A in primary breast cancer can be visualized by 89Zr-bevacizumab PET. Methods: Before surgery, breast cancer patients underwent a PET/CT scan of the breasts and axillary regions 4 d after intravenous administration of 37 MBq of 89Zr-bevacizumab per 5 mg. PET images were compared with standard imaging modalities. 89Zr-bevacizumab uptake was quantified as the maximum standardized uptake value (SUVmax). VEGF-A levels in tumor and normal breast tissues were assessed with enzyme-linked immunosorbent assay. Data are presented as mean ± SD. Results: Twenty-five of 26 breast tumors (mean size ± SD, 25.1 ± 19.8 mm; range, 4–80 mm) in 23 patients were visualized. SUVmax was higher in tumors (1.85 ± 1.22; range, 0.52–5.64) than in normal breasts (0.59 ± 0.37; range, 0.27–1.69; P < 0.001). The only tumor not detected on PET was 10 mm in diameter. Lymph node metastases were present in 10 axillary regions; 4 could be detected with PET (SUVmax, 2.66 ± 2.03; range, 1.32–5.68). VEGF-A levels in the 17 assessable tumors were higher than in normal breast tissue in all cases (VEGF-A/mg protein, 184 ± 169 pg vs. 10 ± 21 pg; P = 0.001), whereas 89Zr-bevacizumab tumor uptake correlated with VEGF-A tumor levels (r = 0.49). Conclusion: VEGF-A in primary breast cancer can be visualized by means of 89Zr-bevacizumab PET.

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.

Detection of micrometastatic breast cancer by means of real time quantitative RT-PCR and immunostaining in perioperative blood samples and sentinel nodes

The aim of our study was to detect micrometastatic breast cancer by epithelial glycoprotein‐2 (EGP‐2) and cytokeratin 19 (CK19), using immunostaining and real time quantitative reverse transcriptase‐polymerase chain reaction (qRT‐PCR). Fifty‐eight breast cancer patients, 52 primary tumors, 75 sentinel nodes (SN) and 149 peripheral blood (PB) samples (from before, during and 4 days after operation) were examined. Immunostaining was performed with antibodies directed against EGP‐2 and CK19. Detection limits were one Michigan Cancer Foundation‐7 (MCF‐7) breast cancer cell line cell/2.106 leukocytes (immunostaining) and one MCF‐7 cell/106 leukocytes qRT‐PCR. Control noncancer lymph nodes (n = 10) showed nonspecific CK19 staining, but were qRT‐PCR negative; control healthy volunteer PB (n = 11) was always negative. Primary tumor samples, all positive with immunostaining, showed a wide variation of EGP‐2 (>104 fold) and CK19 mRNA expression (>103 fold). SN (n = 19) from 16 patients were tumor‐positive with routine haematoxylin‐eosin (H&E) and/or immunostaining. SN tumor presence was positively correlated to qRT‐PCR expression, but 3 tumor‐positive SN were false negative with qRT‐PCR. Three SN were qRT‐PCR positive, while tumor negative with H&E and/or immunostaining. No immunostaining positive PB was observed, but 19 patients (33%) had one or more qRT‐PCR positive PB samples. We concluded that primary tumors have varying expressions of EGP‐2 and CK19 mRNA. Both markers can be used in qRT‐PCR to obtain adequate sensitivity for single tumor cell detection. In SN, immunostaining appears more sensitive/specific than H&E or qRT‐PCR for tumor detection. No immunostaining positivity was found in PB, while 33% of patients had qRT‐PCR positive PB. The clinical value of these findings will have to be clarified.

Zr-89-trastuzumab and Zr-89-bevacizumab PET to Evaluate the Effect of the HSP90 Inhibitor NVP-AUY922 in Metastatic Breast Cancer Patients

Purpose: HSP90 chaperones have key client proteins that are involved in all hallmarks of breast cancer growth and progression. The primary aim of this clinical trial was to evaluate the feasibility of using 89Zr-trastuzumab PET (for HER2-positive breast cancer) or 89Zr-bevacizumab PET [for estrogen receptor (ER)–positive breast cancer] to determine in vivo degradation of client proteins caused by the novel HSP90 inhibitor NVP-AUY922. Experimental Design: Of note, 70 mg/m2 NVP-AUY922 was administered intravenously in a weekly schedule to patients with advanced HER2 or ER-positive breast cancer. Biomarker analysis consisted of serial PET imaging with 2[18F]fluoro-2-deoxy-D-glucose (FDG), 89Zr-trastuzumab, or 89Zr-bevacizumab. Response evaluation was performed according to RECIST1.0. FDG, 89Zr-trastuzumab, and 89Zr-bevacizumab distributions were scored visually and quantitatively by calculating the maximum standardized uptake values (SUVmax). In blood samples, serial HSP70 levels, extracellular form of HER2 (HER2-ECD), and pharmacokinetic and pharmacodynamic parameters were measured. Results: Sixteen patients (ten HER2-positive and six ER-positive tumors) were included. One partial response was observed; seven patients showed stable disease. SUVmax change in individual tumor lesions on baseline versus 3 weeks 89Zr-trastuzumab PET was heterogeneous and related to size change on CT after 8 weeks treatment (r2 = 0.69; P = 0.006). Tumor response on 89Zr-bevacizumab PET and FDG-PET was not correlated with CT response. Conclusions: NVP-AUY922 showed proof-of-concept clinical response in HER2-amplified metastatic breast cancer. Early change on 89Zr-trastuzumab PET was positively associated with change in size of individual lesions assessed by CT. Clin Cancer Res; 20(15); 3945–54. ©2014 AACR.

Internet-based support programs to alleviate psychosocial and physical symptoms in cancer patients: a literature analysis.

In this review the effect of internet-based support programs on psychosocial and physical symptoms resulting from cancer diagnosis and treatment is analyzed. Selection of studies was based on the following criteria: (non-)randomized controlled trials, performed in adult cancer patients, comparing quantitative psychosocial and/or physical outcomes of an internet-based support program with (a) comparison group(s). Literature search yielded 2032 studies of which 16 fulfilled the eligibility criteria. Three different internet-based support programs were identified: social support groups, online therapy for psychosocial/physical symptoms, and online systems integrating information, support, and coaching services. Outcomes improved by these programs in nine studies. Especially fatigue, social support, and distress improved, regardless of the program type. All online systems showed positive effects, mainly for social support and quality of life. This analysis indicates that internet-based support programs are effective in improving psychosocial and physical symptoms in cancer patients.

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.

Antibody Positron Emission Tomography Imaging in Anticancer Drug Development

More than 50 monoclonal antibodies (mAbs), including several antibody-drug conjugates, are in advanced clinical development, forming an important part of the many molecularly targeted anticancer therapeutics currently in development. Drug development is a relatively slow and expensive process, limiting the number of drugs that can be brought into late-stage trials. Development decisions could benefit from quantitative biomarkers, enabling visualization of the tissue distribution of (potentially modified) therapeutic mAbs to confirm effective whole-body target expression, engagement, and modulation and to evaluate heterogeneity across lesions and patients. Such biomarkers may be realized with positron emission tomography imaging of radioactively labeled antibodies, a process called immunoPET. This approach could potentially increase the power and value of early trials by improving patient selection, optimizing dose and schedule, and rationalizing observed drug responses. In this review, we summarize the available literature and the status of clinical trials regarding the potential of immunoPET during early anticancer drug development.