Correlation between Histopathological Prognostic Tumor Characteristics and [18F]FDG Uptake in Corresponding Metastases in Newly Diagnosed Metastatic Breast Cancer

BACKGROUND

In metastatic breast cancer (MBC), [18F]fluorodeoxyglucose positron emission tomography/computed tomography ([18F]FDG-PET/CT) can be used for staging. We evaluated the correlation between BC histopathological characteristics and [18F]FDG uptake in corresponding metastases.

PATIENTS AND METHODS

Patients with non-rapidly progressive MBC of all subtypes prospectively underwent a baseline histological metastasis biopsy and [18F]FDG-PET. Biopsies were assessed for estrogen, progesterone, and human epidermal growth factor receptor 2 (ER, PR, HER2); Ki-67; and histological subtype. [18F]FDG uptake was expressed as maximum standardized uptake value (SUVmax) and results were expressed as geometric means.

RESULTS

Of 200 patients, 188 had evaluable metastasis biopsies, and 182 of these contained tumor. HER2 positivity and Ki-67 ≥ 20% were correlated with higher [18F]FDG uptake (estimated geometric mean SUVmax 10.0 and 8.8, respectively; p = 0.0064 and p = 0.014). [18F]FDG uptake was lowest in ER-positive/HER2-negative BC and highest in HER2-positive BC (geometric mean SUVmax 6.8 and 10.0, respectively; p = 0.0058). Although [18F]FDG uptake was lower in invasive lobular carcinoma (n = 31) than invasive carcinoma NST (n = 146) (estimated geometric mean SUVmax 5.8 versus 7.8; p = 0.014), the metastasis detection rate was similar.

CONCLUSIONS

[18F]FDG-PET is a powerful tool to detect metastases, including invasive lobular carcinoma. Although BC histopathological characteristics are related to [18F]FDG uptake, [18F]FDG-PET and biopsy remain complementary in MBC staging (NCT01957332).

Paclitaxel plus Eftilagimod Alpha, a Soluble LAG-3 Protein, in Metastatic, HR+ Breast Cancer: Results from AIPAC, a Randomized, Placebo Controlled Phase IIb Trial

PURPOSE

Eftilagimod alpha (efti), a soluble lymphocyte activation gene (LAG-3) protein and MHC class II agonist, enhances innate and adaptive immunity. Active Immunotherapy PAClitaxel (AIPAC) evaluated safety and efficacy of efti plus paclitaxel in patients with predominantly endocrine-resistant, hormone receptor-positive, HER2-negative metastatic breast cancer (ET-resistant HR+ HER2- MBC).

PATIENTS AND METHODS

Women with HR+ HER2- MBC were randomized 1:1 to weekly intravenous paclitaxel (80 mg/m2) and subcutaneous efti (30 mg) or placebo every 2 weeks for six 4-week cycles, then monthly subcutaneous efti (30 mg) or placebo maintenance. Primary endpoint was progression-free survival (PFS) by blinded independent central review. Secondary endpoints included overall survival (OS), safety/tolerability, pharmacokinetics/pharmacodynamics, and quality of life. Exploratory endpoints included cellular biomarkers.

RESULTS

114 patients received efti and 112 patients received placebo. Median age was 60 years (91.6% visceral disease, 84.1% ET-resistant, 44.2% with previous CDK4/6 inhibitor treatment). Median PFS at 7.3 months was similar for efti and placebo. Median OS was not significantly improved for efti (20.4 vs. 17.5 months; HR, 0.88; P = 0.197) but became significant for predefined exploratory subgroups. EORTC QLQC30-B23 global health status was sustained for efti but deteriorated for placebo. Efti increased absolute lymphocyte, monocyte and secondary target cell (CD4, CD8) counts, plasma IFNγ and CXCL10 levels.

CONCLUSIONS

Although the primary endpoint, PFS, was not met, AIPAC confirmed expected pharmacodynamic effects and demonstrated excellent safety profile for efti. OS was not significantly improved globally (2.9-month difference), but was significantly improved in exploratory biomarker subgroups, warranting further studies to clarify efti's role in patients with ET-resistant HER2- MBC.

Glycogen synthase 1 targeting reveals a metabolic vulnerability in triple-negative breast cancer

BACKGROUND

Hypoxia-induced glycogen turnover is implicated in cancer proliferation and therapy resistance. Triple-negative breast cancers (TNBCs), characterized by a hypoxic tumor microenvironment, respond poorly to therapy. We studied the expression of glycogen synthase 1 (GYS1), the key regulator of glycogenesis, and other glycogen-related enzymes in primary tumors of patients with breast cancer and evaluated the impact of GYS1 downregulation in preclinical models.

METHODS

mRNA expression of GYS1 and other glycogen-related enzymes in primary breast tumors and the correlation with patient survival were studied in the METABRIC dataset (n = 1904). Immunohistochemical staining of GYS1 and glycogen was performed on a tissue microarray of primary breast cancers (n = 337). In four breast cancer cell lines and a mouse xenograft model of triple-negative breast cancer, GYS1 was downregulated using small-interfering or stably expressed short-hairpin RNAs to study the effect of downregulation on breast cancer cell proliferation, glycogen content and sensitivity to various metabolically targeted drugs.

RESULTS

High GYS1 mRNA expression was associated with poor patient overall survival (HR 1.20, P = 0.009), especially in the TNBC subgroup (HR 1.52, P = 0.014). Immunohistochemical GYS1 expression in primary breast tumors was highest in TNBCs (median H-score 80, IQR 53-121) and other Ki67-high tumors (median H-score 85, IQR 57-124) (P < 0.0001). Knockdown of GYS1 impaired proliferation of breast cancer cells, depleted glycogen stores and delayed growth of MDA-MB-231 xenografts. Knockdown of GYS1 made breast cancer cells more vulnerable to inhibition of mitochondrial proteostasis.

CONCLUSIONS

Our findings highlight GYS1 as potential therapeutic target in breast cancer, especially in TNBC and other highly proliferative subsets.

Molecular imaging as biomarker for treatment response and outcome in breast cancer

Molecular imaging, such as positron emission tomography (PET), is increasingly used as biomarker to predict and assess treatment response in breast cancer. The number of biomarkers is expanding with specific tracers for tumour characteristics throughout the body and this information can be used to aid the decision-making process. These measurements include metabolic activity using [18F]fluorodeoxyglucose PET ([18F]FDG-PET), oestrogen receptor (ER) expression using 16α-[18F]Fluoro-17β-oestradiol ([18F]FES)-PET and human epidermal growth factor receptor 2 (HER2) expression using PET with radiolabelled trastuzumab (HER2-PET). In early breast cancer, baseline [18F]FDG-PET is frequently used for staging, but limited subtype-specific data reduce its usefulness as biomarker for treatment response or outcome. Early metabolic change on serial [18F]FDG-PET is increasingly used in the neo-adjuvant setting as dynamic biomarker to predict pathological complete response to systemic therapy, potentially allowing de-intensification or step-up intensification of treatment. In the metastatic setting, baseline [18F]FDG-PET and [18F]FES-PET can be used as biomarker to predict treatment response, in triple-negative and ER-positive breast cancer, respectively. Metabolic progression on repeated [18F]FDG-PET appears to precede progressive disease on standard evaluation imaging; however, subtype-specific studies are limited and more prospective data are needed before implementation in clinical practice. Even though (repeated) [18F]FDG-PET, [18F]FES-PET and HER2-PEt all show promising results as biomarkers to predict therapy response and outcome, for eventual integration into clinical practice, future studies will have to clarify at what timepoint this integration has to optimally take place.

Validation of the 70-gene signature test (MammaPrint) to identify patients with breast cancer aged ≥ 70 years with ultralow risk of distant recurrence: A population-based cohort study

INTRODUCTION

When risk estimation in older patients with hormone receptor positive breast cancer (HR + BC) is based on the same factors as in younger patients, age-related factors regarding recurrence risk and other-cause mortality are not considered. Genomic risk assessment could help identify patients with ultralow risk BC who can forgo adjuvant treatment. However, assessment tools should be validated specifically for older patients. This study aims to determine whether the 70-gene signature test (MammaPrint) can identify patients with HR + BC aged ≥70 years with ultralow risk for distant recurrence.

MATERIALS AND METHODS

Inclusion criteria: ≥70 years; invasive HR + BC; T1-2N0-3M0.

EXCLUSION CRITERIA

HER2 + BC; neoadjuvant therapy. MammaPrint assays were performed following standardized protocols. Clinical risk was determined with St. Gallen risk classification. Primary endpoint was 10-year cumulative incidence rate of distant recurrence in relation to genomic risk. Subdistribution hazard ratios (sHR) were estimated from Fine and Gray analyses. Multivariate analyses were adjusted for adjuvant endocrine therapy and clinical risk.

RESULTS

This study included 418 patients, median age 78 years (interquartile range [IQR] 73-83). Sixty percent of patients were treated with endocrine therapy. MammaPrint classified 50 patients as MammaPrint-ultralow, 224 patients as MammaPrint-low, and 144 patients as MammaPrint-high risk. Regarding clinical risk, 50 patients were classified low, 237 intermediate, and 131 high. Discordance was observed between clinical and genomic risk in 14 MammaPrint-ultralow risk patients who were high clinical risk, and 84 patients who were MammaPrint-high risk, but low or intermediate clinical risk. Median follow-up was 9.2 years (IQR 7.9-10.5). The 10-year distant recurrence rate was 17% (95% confidence interval [CI] 11-23) in MammaPrint-high risk patients, 8% (4-12) in MammaPrint-low (HR 0.46; 95%CI 0.25-0.84), and 2% (0-6) in MammaPrint-ultralow risk patients (HR 0.11; 95%CI 0.02-0.81). After adjustment for clinical risk and endocrine therapy, MammaPrint-high risk patients still had significantly higher 10-year distant recurrence rate than MammaPrint-low (sHR 0.49; 95%CI 0.26-0.90) and MammaPrint-ultralow patients (sHR 0.12; 95%CI 0.02-0.85). Of the 14 MammaPrint-ultralow, high clinical risk patients none developed a distant recurrence.

DISCUSSION

These data add to the evidence validating MammaPrint's ultralow risk threshold. Even in high clinical risk patients, MammaPrint-ultralow risk patients remained recurrence-free ten years after diagnosis. These findings justify future studies into using MammaPrint to individualize adjuvant treatment in older patients.

Clinical Validity of 16α-[18F]Fluoro-17β-Estradiol Positron Emission Tomography/Computed Tomography to Assess Estrogen Receptor Status in Newly Diagnosed Metastatic Breast Cancer

PURPOSE

Determining the estrogen receptor (ER) status is essential in metastatic breast cancer (MBC) management. Whole-body ER imaging with 16α-[¹⁸F]fluoro-17β-estradiol positron emission tomography ([¹⁸F]FES-PET) is increasingly used for this purpose. To establish the clinical validity of the [¹⁸F]FES-PET, we studied the diagnostic accuracy of qualitative and quantitative [¹⁸F]FES-PET assessment to predict ER expression by immunohistochemistry in a metastasis.

METHODS

In a prospective multicenter trial, 200 patients with newly diagnosed MBC underwent extensive workup including molecular imaging. For this subanalysis, ER expression in the biopsied metastasis was related to qualitative whole-body [¹⁸F]FES-PET evaluation and quantitative [¹⁸F]FES uptake in the corresponding metastasis. A review and meta-analysis regarding [¹⁸F]FES-PET diagnostic performance were performed.

RESULTS

Whole-body [¹⁸F]FES-PET assessment predicted ER expression in the biopsied metastasis with good accuracy: a sensitivity of 95% (95% CI, 89 to 97), a specificity of 80% (66 to 89), a positive predictive value (PPV) of 93% (87 to 96), and a negative predictive value (NPV) of 85% (72 to 92) in 181 of 200 evaluable patients. Quantitative [¹⁸F]FES uptake predicted ER immunohistochemistry in the corresponding metastasis with a sensitivity/specificity of 91%/69% and a PPV/NPV of 90%/71% in 156 of 200 evaluable patients. For bone metastases, PPV/NPV was 92%/81%. Meta-analysis with addition of our data has increased diagnostic performance and narrowed the 95% CIs compared with previous studies with a sensitivity/specificity of both 86% (81 to 90 and 73 to 93, respectively).

CONCLUSION

In this largest prospective series so far, we established the clinical validity of [¹⁸F]FES-PET to determine tumor ER status in MBC. In view of the high diagnostic accuracy of qualitatively assessed whole-body [¹⁸F]FES-PET, this noninvasive imaging modality can be considered a valid alternative to a biopsy of a metastasis to determine ER status in newly MBC (ClinicalTrials.gov identifier: NCT01957332).

Radiolabeled Monoclonal Antibody Against Colony-Stimulating Factor 1 Receptor Specifically Distributes to the Spleen and Liver in Immunocompetent Mice

Macrophages can promote tumor development. Preclinically, targeting macrophages by colony-stimulating factor 1 (CSF1)/CSF1 receptor (CSF1R) monoclonal antibodies (mAbs) enhances conventional therapeutics in combination treatments. The physiological distribution and tumor uptake of CSF1R mAbs are unknown. Therefore, we radiolabeled a murine CSF1R mAb and preclinically visualized its biodistribution by PET. CSF1R mAb was conjugated to N-succinyl-desferrioxamine (N-suc-DFO) and subsequently radiolabeled with zirconium-89 (89Zr). Optimal protein antibody dose was first determined in non-tumor-bearing mice to assess physiological distribution. Next, biodistribution of optimal protein dose and 89Zr-labeled isotype control was compared with PET and ex vivo biodistribution after 24 and 72 h in mammary tumor-bearing mice. Tissue autoradiography and immunohistochemistry determined radioactivity distribution and tissue macrophage presence, respectively. [89Zr]Zr-DFO-N-suc-CSF1R-mAb optimal protein dose was 10 mg/kg, with blood pool levels of 10 ± 2% injected dose per gram tissue (ID/g) and spleen and liver uptake of 17 ± 4 and 11 ± 4%ID/g at 72 h. In contrast, 0.4 mg/kg of [89Zr]Zr-DFO-N-suc-CSF1R mAb was eliminated from circulation within 24 h; spleen and liver uptake was 126 ± 44% and 34 ± 7%ID/g, respectively. Tumor-bearing mice showed higher uptake of [89Zr]Zr-DFO-N-suc-CSF1R-mAb in the liver, lymphoid tissues, duodenum, and ileum, but not in the tumor than did 89Zr-labeled control at 72 h. Immunohistochemistry and autoradiography showed that 89Zr was localized to macrophages within lymphoid tissues. Following [89Zr]Zr-DFO-N-suc-CSF1R-mAb administration, tumor macrophages were almost absent, whereas isotype-group tumors contained over 500 cells/mm2. We hypothesize that intratumoral macrophage depletion by [89Zr]Zr-DFO-N-suc-CSF1R-mAb precluded tumor uptake higher than 89Zr-labeled control. Translation of molecular imaging of macrophage-targeting therapeutics to humans may support macrophage-directed therapeutic development.

Analyzing the Estrogen Receptor Status of Liver Metastases with [18F]-FES-PET in Patients with Breast Cancer

Background: Positron emission tomography (PET) with 16α-[¹⁸F]-fluoro-17β-estradiol ([¹⁸F]-FES) can visualize estrogen receptor (ER) expression, but it is challenging to determine the ER status of liver metastases, due to high physiological [¹⁸F]-FES uptake. We evaluated whether [¹⁸F]-FES-PET can be used to determine the ER status of liver metastases, using corresponding liver biopsies as the gold standard. Methods: Patients with metastatic breast cancer (n = 23) were included if they had undergone a [¹⁸F]-FES-PET, liver metastasis biopsy, CT-scan, and [¹⁸F]-FDG-PET. [¹⁸F]-FES-PET scans were assessed by visual and quantitative analysis, tracer uptake was correlated with ER expression measured by immunohistochemical staining and the effects of region-of-interest size and background correction were determined. Results: Visual analysis allowed ER assessment of liver metastases with 100% specificity and 18% sensitivity. Quantitative analysis improved the sensitivity. Reduction of the region-of-interest size did not further improve the results, but background correction improved ER assessment, resulting in 83% specificity and 77% sensitivity. Using separate thresholds for ER+ and ER− metastases, positive and negative predictive values of 100% and 75%, respectively, could be obtained, although 30% of metastases remained inconclusive. Conclusion: In the majority of liver metastases, ER status can be determined with [¹⁸F]-FES-PET if background correction and separate thresholds are applied.

Abstract LB037: 89ZED88082A PET imaging to visualize CD8+ T cells in patients with cancer treated with immune checkpoint inhibitor

T cell enhancing immune checkpoint inhibitors (ICI) are effective across several tumor types in a subset of patients. Insights into systemic localization of cytotoxic CD8+ T cells might support early treatment decisions. To address this, we performed a PET imaging study with a zirconium-89 (89Zr) labeled one-armed CD8-specific antibody 89ZED88082A to assess tracer performance, safety, and pharmacokinetics (PK) before and during treatment. Here we report preliminary data on uptake in tumor lesions before ICI. Methods: Patients with locally advanced or metastatic solid tumors that may benefit from ICI are eligible. In part A (imaging before treatment) and part B (imaging before and during treatment), 37 MBq (1 mCi) 89ZED88082A is administered with unlabeled one-armed antibody CED88004S to vary total protein dose. PET images are acquired at up to 4 time points: 1 h, and days (d) 2, 4, 7 post-injection followed by a tumor biopsy for CD8 immunohistochemistry and autoradiography (NCT04029181). Subsequently, patients receive atezolizumab (NCT02478099) or standard of care nivolumab ± ipilimumab. Tumor and lymph node 89ZED88082A uptake are assessed as (geometric mean) maximum standard uptake value (SUVmax), in other organs as SUVmean. Serum 89ZED88082A/CED88004S levels are measured for PK. Tumor response is according to (i)RECIST1.1. Results: For pretreatment imaging results, 32 patients (9 part A, 23 part B) were evaluable; 3 received 4 mg total tracer protein dose, 29 received 10 mg. No tracer infusion-related reactions occurred. Here we show results on d2 PET imaging with 10 mg protein dose, which was considered optimal based on superior 89Zr blood pool activity, clinical feasibility and serum antibody PK with a half-life of 28.6 h. 89ZED88082A uptake was observed within 1 h in spleen, and strong d2 imaging signal was seen across lymphoid organs including spleen (\bar{x}$ SUVmean 47.2), lymph nodes (SUVmax 4.2), bone marrow (\bar{x}$ SUVmean 5.0), small bowel and Waldeyer's ring. 89ZED88082A tumor uptake was seen at all main metastatic organ sites (overall lesion SUVmax 5.5, range 0.6-30.9) and varied across patients (\bar{x}$ per patient SUVmax 5.4, IQR 3.8-7.4). Higher tumor uptake showed a trend with better response (p=0.059) and longer PFS (p=0.033). Tumor uptake was higher in patients with mismatch-repair deficient (dMMR) than MMR proficient tumors (SUVmax 9.3 vs 4.9, p&lt;0.001). Tumors with immune desert vs CD8+ cell stromal/inflamed profile had a \bar{x}$ SUVmax of 4.7 vs 8.3 (p=0.042). In tumor biopsies, autoradiography signal and CD8 staining were linearly associated (p&lt;0.001). Conclusion: 89ZED88082A PET imaging is safe and shows high uptake in normal lymphoid organs. Uptake in tumor lesions is heterogeneous within and between patients. Tumor uptake is higher pretreatment in dMMR tumors and correlated with patient outcome. 89ZED88082A uptake on PET and by autoradiography reflects CD8 expression in tumor biopsies.

Citation Format: Laura Kist de Ruijter, Pim P. van de Donk, Jahlisa S. Hooiveld-Noeken, Danique Giesen, Alexander Ungewickell, Bernard M. Fine, Simon P. Williams, Sandra M. Sanabria Bohorquez, Mahesh Yadav, Hartmut Koeppen, Jing Jing, Sebastian Guelman, Mark T. Lin, Michael J. Mamounas, Jeffrey Eastham, Patrick K. Kimes, Andor W. Glaudemans, Adrienne H. Brouwers, Marjolijn N. Lub-de Hooge, Jourik A. Gietema, Carolina P. Schröder, Wim Timens, Mathilde Jalving, Sjoerd Elias, Sjoukje F. Oosting, Derk J. de Groot, Elisabeth G. de Vries. 89ZED88082A PET imaging to visualize CD8+ T cells in patients with cancer treated with immune checkpoint inhibitor [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr LB037.

Preclinical PET imaging of bispecific antibody ERY974 targeting CD3 and glypican 3 reveals that tumor uptake correlates to T cell infiltrate

BACKGROUND

Bispecific antibodies redirecting T cells to the tumor obtain increasing interest as potential cancer immunotherapy. ERY974, a full-length bispecific antibody targeting CD3ε on T cells and glypican 3 (GPC3) on tumors, has been in clinical development However, information on the influence of T cells on biodistribution of bispecific antibodies, like ERY974, is scarce. Here, we report the biodistribution and tumor targeting of zirconium-89 (⁸⁹Zr) labeled ERY974 in mouse models using immuno-positron emission tomography (PET) imaging.

METHODS

To study both the role of GPC3 and CD3 on the biodistribution of [⁸⁹Zr]Zr-N-suc-Df-ERY974, ⁸⁹Zr-labeled control antibodies targeting CD3 and non-mammalian protein keyhole limpet hemocyanin (KLH) or KLH only were used. GPC3 dependent tumor targeting of [⁸⁹Zr]Zr-N-suc-Df-ERY974 was tested in xenograft models with different levels of GPC3 expression. In addition, CD3 influence on biodistribution of [⁸⁹Zr]Zr-N-suc-Df-ERY974 was evaluated by comparing biodistribution between tumor-bearing immunodeficient mice and mice reconstituted with human immune cells using microPET imaging and ex vivo biodistribution. Ex vivo autoradiography was used to study deep tissue distribution.

RESULTS

In tumor-bearing immunodeficient mice, [⁸⁹Zr]Zr-N-suc-Df-ERY974 tumor uptake was GPC3 dependent and specific over [⁸⁹Zr]Zr-N-suc-Df-KLH/CD3 and [⁸⁹Zr]Zr-N-suc-Df-KLH/KLH. In mice engrafted with human immune cells, [⁸⁹Zr]Zr-N-suc-Df-ERY974 specific tumor uptake was higher than in immunodeficient mice. Ex vivo autoradiography demonstrated a preferential distribution of [⁸⁹Zr]Zr-N-suc-Df-ERY974 to T cell rich tumor tissue. Next to tumor, highest specific [⁸⁹Zr]Zr-N-suc-Df-ERY974 uptake was observed in spleen and lymph nodes.

CONCLUSION

^[89Zr]Zr-N-suc-Df-ERY974 can potentially be used to study ERY974 biodistribution in patients to support drug development.

Effects of supervised exercise during adjuvant endocrine therapy in overweight or obese patients with breast cancer: The I-MOVE study

Background

Adjuvant endocrine therapy (ET) in patients with breast cancer (BC) increases the risk of becoming less physically active. Physical inactivity is associated with a higher risk of treatment-related side effects and mortality. This study investigated whether supervised exercise increased the proportion of patients adhering to the national physical activity (PA) guideline during adjuvant ET in overweight or obese BC patients.

Methods

This multicentre single-arm clinical trial included patients with BC participating in a 12-week supervised exercise intervention. An accelerometer measured moderate to vigorous PA (MVPA) at baseline (T0), after 12 (T1) and 26 weeks (T2). The primary endpoint was change in the proportion of patients with weekly ≥150 min of MVPA at T1 compared to T0. Secondary endpoints were adherence to PA guideline at T2, metabolic syndrome (MetS), body composition, health-related quality of life (HRQoL) and BC-specific functioning and symptoms, self-reported PA, self-efficacy, exercise motivation and satisfaction with life.

Results

141 patients with a median age of 61 years and a mean BMI of 31.3 participated. Adherence to the PA guideline increased from 38.3% at T0, to 40.4% at T1 (p = .112) and 44.7% at T2 (p = .003). MetS, body composition, HRQoL, BC-specific functioning and symptoms (i.e. fatigue, dyspnoea), self-reported PA, self-efficacy, exercise motivation and satisfaction with life improved significantly over time.

Conclusions

Supervised exercise increased the proportion of BC patients adhering to the PA guideline over time. Furthermore, MetS, body composition, HRQoL and symptoms improved. Our findings highlight the clinical relevance of supervised exercise during ET in overweight BC patients.

Clinical trial information

(NCT02424292).

•

Overweight breast cancer patients on endocrine therapy can be motivated for supervised exercise.

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Supervised exercise increases adherence to the physical activity guideline.

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Metabolic syndrome and quality of life improved due to our intervention.

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Participation in supervised exercise induces persistent clinical improvements.

Value of 18F-FES PET in Solving Clinical Dilemmas in Breast Cancer Patients: A Retrospective Study

Breast cancer (BC) is a heterogeneous disease in which estrogen receptor (ER) expression plays an important role in most tumors. A clinical dilemma may arise when a metastasis biopsy to determine the ER status cannot be performed safely or when ER heterogeneity is suspected between tumor lesions. Whole-body ER imaging, such as 16α-¹⁸F-fluoro-17β-estradiol (¹⁸F-FES) PET, may have added value in these situations. However, the role of this imaging technique in routine clinical practice remains to be further determined. Therefore, we assessed whether the physician's remaining clinical dilemma after the standard workup was solved by the ¹⁸F-FES PET scan. Methods: This retrospective study included ¹⁸F-FES PET scans of patients who had (or were suspected to have) ER-positive metastatic BC and for whom a clinical dilemma remained after the standard workup. The scans were performed at the University Medical Center of Groningen between November 2009 and January 2019. We investigated whether the physician's clinical dilemma was solved, defined either as solving the clinical dilemma through the ¹⁸F-FES PET results or as basing a treatment decision directly on the ¹⁸F-FES PET results. In addition, the category of the clinical dilemma was reported, as well as the rate of ¹⁸F-FES-positive or -negative PET scans, and any correlation to the frequency of solved dilemmas was determined. Results: One hundred ¹⁸F-FES PET scans were performed on 83 patients. The clinical dilemma categories were inability to determine the extent of metastatic disease or suspected metastatic disease with the standard workup (n = 52), unclear ER status of the tumor (n = 31), and inability to determine which primary tumor caused the metastases (n = 17). The dilemmas were solved by ¹⁸F-FES PET in 87 of 100 scans (87%). In 81 of 87 scans, a treatment decision was based directly on ¹⁸F-FES PET results (treatment change, 51 scans; continuance, 30 scans). The frequency of solved dilemmas was not related to the clinical dilemma category (P = 0.334). However, the frequency of solved dilemmas was related to whether scans were ¹⁸F-FES-positive (n = 63) or ¹⁸F-FES-negative (n = 37; P < 0.001). Conclusion: For various indications, the ¹⁸F-FES PET scan can help to solve most clinical dilemmas that may remain after the standard workup. Therefore, the ¹⁸F-FES PET scan has added value in BC patients who present the physician with a clinical dilemma.

Detection of Dural Metastases Before the Onset of Clinical Symptoms by 16α-[18F]Fluoro-17β-Estradiol PET in a Patient With Estrogen Receptor-Positive Breast Cancer

ABSTRACT

We offer an illustrative case about estrogen receptor (ER) imaging (also known as 16α-[18F]fluoro-17β-estradiol ([18F]-FES) PET) and the detection of metastatic lesions in the dural region. We present a case of a woman with ER-positive metastatic breast cancer and high [18F]-FES uptake in the dural region on PET imaging, without associated clinical symptoms. These lesions were missed on [18F]-FDG PET because of physiological [18F]-FDG uptake in the brain. This case highlighted some difficulties in the interpretation of imaging of brain metastases and demonstrated the added value of [18F]-FES PET imaging. [18F]-FES PET could be used to prove the presence of ER-positive metastases in the brain.

Abstract PS3-05: Value of [18F]-FES-PET to solve clinical dilemmas in breast cancer patients: A retrospective study

Introduction: Breast cancer (BC) is a heterogeneous disease, in which estrogen receptor (ER) expression plays an important role in the majority of breast tumors. A clinical dilemma may arise when a metastasis biopsy to determine the ER status cannot be performed safely or when ER heterogeneity is suspected between tumor lesions. Whole-body ER imaging, such as 16α-[18F]-fluoro-17β-estradiol ([18F]-FES) positron emission tomography (PET), may have additional value in these situations. However, the role of this imaging technique in routine clinical practice remains to be further determined. Therefore, we assessed the value of [18F]-FES-PET in a large retrospective set of patients, by evaluating if the physicians’ clinical dilemma that remained after standard workup was solved by the [18F]-FES-PET scan. Methods: In this single center study, [18F]-FES-PET scans, performed in patients with (suspected) ER+ metastatic BC with remaining clinical dilemma after standard workup (such as computed tomography, [18F]-fluorodeoxyglucose ([18F]-FDG)-PET, bone scintigraphy, magnetic resonance imaging, or biopsy), performed at the UMCG between November 2009 and January 2019, were included. A whole-body [18F]-FES-PET scan was performed 60 min after ~200 MBq of [18F]-FES was injected intravenously. ER antagonists had to be discontinued at least 5 weeks before [18F]-FES-PET. Primary endpoint was the percentage of cases in which the referring physician’s clinical dilemma was solved based on the [18F]-FES-PET results. The dilemma was considered solved if 1) the [18F]-FES-PET provided a solution for the clinical dilemma (for example an extra metastatic site to biopsy), or 2) a treatment decision (to change or continue) was made based on the [18F]-FES-PET result. If the physician had doubts about the diagnosis after the [18F]-FES-PET examination, and additional workup was necessary for treatment decision-making, the dilemma was considered not solved. Secondary endpoints were type of clinical dilemma, and rate of [18F]-FES positive or negative PET scans (visual interpretation), related to frequency of solved dilemmas. Results: One hundred [18F]-FES-PET scans were performed in 83 patients. Clinical dilemma types were: 1) inability to determine extent of (suspected) metastatic disease with standard workup (n=52), 2) unclear disease ER status (n=31), and 3) inability to determine which primary tumor caused metastases (n=17). Dilemmas were solved by [18F]-FES-PET in 87/100 cases (87%). In these 87 cases, treatment was changed in 52 cases, and continued in 35 cases. The frequency of solved dilemmas was not related to the type of clinical dilemma. In contrast, the frequency of solved dilemmas was related to whether scans were [18F]-FES positive or negative. Out of the 63 [18F]-FES positive scans, the clinical dilemma was solved in 61 cases (97%); in 26 out of the 37 [18F]-FES negative scans (70%) the dilemma was solved (p&lt;0.001). Conclusion: In this real life study of BC patients with a clinical dilemma after standard workup, we showed that [18F]-FES-PET solved the dilemma in the large majority of cases. Relevant treatment decisions were made based on the scan, particularly in ER+ disease. This indicates that the [18F]-FES-PET can be of value to solve clinical dilemmas in BC patients. Ultimately, this can support optimal treatment in these patients and potentially improve outcome. Prospective trials are currently ongoing to further assess this.

Citation Format: Jorianne Boers, Naila Loudini, Celina L. Brunsch, Sylvia A. Koza, Erik F.J. de Vries, Andor W.J.M. Glaudemans, Geke A.P. Hospers, Carolina P. Schröder. Value of [18F]-FES-PET to solve clinical dilemmas in breast cancer patients: A retrospective study [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS3-05.

Serial [18F]-FDHT-PET to predict bicalutamide efficacy in patients with androgen receptor positive metastatic breast cancer

BACKGROUND

The androgen receptor (AR) is a potential target in metastatic breast cancer (MBC), and 16β-[¹⁸F]-fluoro-5α-dihydrotestosterone positron emission tomography ([¹⁸F]-FDHT-PET) can be used for noninvasive visualisation of AR. [¹⁸F]-FDHT uptake reduction during AR-targeting therapy reflects AR occupancy and might be predictive for treatment response. We assessed the feasibility of [¹⁸F]-FDHT-PET to detect changes in AR availability during bicalutamide treatment and correlated these changes with treatment response.

PATIENTS AND METHODS

Patients with AR + MBC, regardless of oestrogen receptor status, received an [¹⁸F]-FDHT-PET at baseline and after 4-6 weeks bicalutamide treatment. Baseline [¹⁸F]-FDHT uptake was expressed as maximum standardised uptake value. Percentage change in tracer uptake, corrected for background activity (SUV_cor), between baseline and follow-up PET scan (% reduction), was assessed per-patient and lesion. Clinical benefit was determined in accordance with Response Evaluation Criteria in Solid Tumours (RECIST) 1.1 or clinical evaluation (absence of disease progression for ≥24 weeks).

RESULTS

Baseline [¹⁸F]-FDHT-PET in 21 patients detected 341 of 515 lesions found with standard imaging and 21 new lesions. Follow-up [¹⁸F]-FDHT-PET was evaluable in 17 patients with 349 lesions, showing a decrease in median SUV_cor from 1.3 to 0.7 per-patient and lesion (P < 0.001). Median % reduction per-patient was -45% and per-lesion -39%. In patients with progressive disease (n = 11), median % reduction was -30% versus -53% for patients who showed clinical benefit (in accordance with RECIST (n = 3) or clinical evaluation (n = 3); P = 0.338).

CONCLUSION

In this feasibility study, a bicalutamide-induced reduction in [¹⁸F]-FDHT uptake could be detected by follow-up [¹⁸F]-FDHT-PET in patients with AR + MBC. However, this change could not predict bicalutamide response.

CLINICAL TRIAL INFORMATION

NCT02697032.

Image Quality and Interpretation of [18F]-FES-PET: Is There any Effect of Food Intake?

Background: High physiological 16α-[¹⁸F]-fluoro-17β-estradiol ([¹⁸F]-FES) uptake in the abdomen is a limitation of this positron emission tomography (PET) tracer. Therefore, we investigated the effect of food intake prior to PET acquisition on abdominal background activity in [¹⁸F]-FES-PET scans. Methods: Breast cancer patients referred for [¹⁸F]-FES-PET were included. Three groups were designed: (1) patients who consumed a chocolate bar (fatty meal) between tracer injection and imaging (n = 20), (2) patients who fasted before imaging (n = 20), and (3) patients without diet restrictions (control group, n = 20). We compared the physiological [¹⁸F]-FES uptake, expressed as mean standardized uptake value (SUV_mean), in the abdomen between groups. Results: A significant difference in [¹⁸F]-FES uptake in the gall bladder and stomach lumen was observed between groups, with the lowest values for the chocolate group and highest for the fasting group (p = 0.015 and p = 0.011, respectively). Post hoc analysis showed significant differences in the SUVmean of these organs between the chocolate and fasting groups, but not between the chocolate and control groups. Conclusion: This exploratory study showed that, compared to fasting, eating chocolate decreases physiological gall bladder and stomach [¹⁸F]-FES uptake; further reduction through a normal diet was not seen. A prospective study is warranted to confirm this finding.

Assessment of Bone Lesions with 18F-FDG PET Compared with 99mTc Bone Scintigraphy Leads to Clinically Relevant Differences in Metastatic Breast Cancer Management

It is unknown whether assessment of potential bone lesions in metastatic breast cancer (MBC) by ¹⁸F-FDG PET instead of ^99mTc bone scintigraphy (BS) supports clinically relevant changes in MBC management. Therefore, we retrospectively compared management recommendations based on bone lesion assessment by ¹⁸F-FDG PET plus contrast-enhanced CT (ceCT) or BS plus ceCT, for patients with newly diagnosed MBC. Methods: Baseline ceCT, BS, and ¹⁸F-FDG PET for all patients included in the IMPACT-MBC study (NCT01957332) at the University Medical Center Groningen were reviewed for bone lesions. If bone lesions were found by any imaging modality, virtual MBC management recommendations were made by a multidisciplinary expert panel, based on either ¹⁸F-FDG PET plus ceCT or BS plus ceCT. The panel had access to standard clinicopathologic information and baseline imaging findings outside the skeleton. Clinically relevant management differences between the 2 recommendations were defined either as different treatment intent (curative, noncurative, or unable to determine) or as different systemic or local treatment. If no bone lesions were found by any imaging modality, the patients were included in the analyses without expert review. Results: In total, 3,473 unequivocal bone lesions were identified in 102 evaluated patients (39% by ceCT, 26% by BS, and 87% by ¹⁸F-FDG PET). Additional bone lesions on ¹⁸F-FDG PET plus ceCT compared with BS plus ceCT led to change in MBC management recommendations in 16% of patients (95% CI, 10%-24%). BS also changed management compared with ¹⁸F-FDG PET in 1 patient (1%; 95% CI, 0%-5%). In 26% (95% CI, 19%-36%) of patients, an additional ¹⁸F-FDG PET exam was requested, because BS provided insufficient information. Conclusion: In this exploratory analysis of newly diagnosed MBC patients, ¹⁸F-FDG PET versus BS to assess bone lesions resulted in clinically relevant management differences in 16% of patients. BS delivered insufficient information in over one fourth of patients, resulting in an additional request for ¹⁸F-FDG PET. On the basis of these data, ¹⁸F-FDG PET should be considered a primary imaging modality for assessment of bone lesions in newly diagnosed MBC.

Abstract 4002: Adipose tissue supernatant of overweight ER positive breast cancer patients promotes migration of MCF-7 breast cancer cells

Introduction: Adipose tissue is a major component of the breast cancer microenvironment, and preclinical studies have suggested that adipose tissue might play a pivotal role in breast cancer progression. In this study we investigated the effect of adipose tissue from patients with ER positive breast cancer on migration of ER positive MCF-7 breast cancer cells.

Materials and Methods: Adipose tissue samples were collected from patients with ER positive breast cancer undergoing a mastectomy. In total, adipose tissue samples from 3 normal weight (BMI: 18.5-24.9) and 7 overweight breast cancer patients (BMI: 25-29.9) were collected. Samples from the mastectomy specimens were minced in small pieces, incubated in RPMI-1640 and after 48 hours (h) the supernatant was harvested. The effect of adipose tissue supernatant on the migration of MCF-7 cells was monitored in real-time for 48 h with the xCELLigence cell invasion and migration plates expressed in delta cell index (DCI). In addition, effect of adipose tissue supernatant on migration was assessed by quantification of F-actin positive lamellipodia of MCF-7 cells in a scratch assay after 24 h. In all experiments, RPMI-1640 with 1% or 20% FCS was used as a negative or positive control respectively.

Results: Supernatant of overweight patients significantly induced MCF-7 migration compared to supernatant of normal weight patients after 24 h (xCELLigence DCI: 1.22 ± 0.15 vs. 0.95 ± 0.19 (P=0.038)), 36 h (DCI 1.40 ± 0.21 vs. 0.91 ± 0.31 (P=0.019)) and 48 h (DCI 1.72 ± 0.23 vs. 0.98 ± 0.43 (P=0.007)). In addition, there was a significant difference between the overweight group and negative control at 36 h, and 48 h (DCI 1.40 ± 0.21 vs. 1.06 ± 0.12, P=0.038 and DCI 1.72 ± 0.23 vs. 1.11 ± 0.21, P=0.004 respectively). No significant difference between normal weight group and negative control was found at any of the time points. After 24 h MCF-7 cells incubated with supernatant of overweight patients developed significantly more F-actin positive lamellipodia compared to MCF-7 cells incubated with supernatant of normal weight patients (44.26 ± 3.26% vs. 25.47 ± 1.88% P&lt;0.001).

Conclusion: In this study, we showed that adipose tissue supernatant of patients with ER positive breast cancer can promote migration of MCF-7 breast cancer cells in a weight dependent manner. Whether this is the case in other breast cancer subtypes as well, and the potential clinical implication, is of interest for future studies.

Citation Format: Jie Ma, Hetty Timmer-Bosscha, Paul M. Werker, Carolina P. Schröder, Marlous Arjaans. Adipose tissue supernatant of overweight ER positive breast cancer patients promotes migration of MCF-7 breast cancer cells [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 4002.

Application of PET Tracers in Molecular Imaging for Breast Cancer

PURPOSE OF REVIEW

Molecular imaging with positron emission tomography (PET) is a powerful tool to visualize breast cancer characteristics. Nonetheless, implementation of PET imaging into cancer care is challenging, and essential steps have been outlined in the international "imaging biomarker roadmap." In this review, we identify hurdles and provide recommendations for implementation of PET biomarkers in breast cancer care, focusing on the PET tracers 2-[18F]-fluoro-2-deoxyglucose ([18F]-FDG), sodium [18F]-fluoride ([18F]-NaF), 16α-[18F]-fluoroestradiol ([18F]-FES), and [89Zr]-trastuzumab.

RECENT FINDINGS

Technical validity of [18F]-FDG, [18F]-NaF, and [18F]-FES is established and supported by international guidelines. However, support for clinical validity and utility is still pending for these PET tracers in breast cancer, due to variable endpoints and procedures in clinical studies. Assessment of clinical validity and utility is essential towards implementation; however, these steps are still lacking for PET biomarkers in breast cancer. This could be solved by adding PET biomarkers to randomized trials, development of imaging data warehouses, and harmonization of endpoints and procedures.

Distress, problems, referral wish, and supportive health care use in breast cancer survivors beyond the first year after chemotherapy completion

PURPOSE

We examined distress levels, problems, referral wish, and supportive health care use in a cross-sectional group of breast cancer survivors at two-time points with a 1-year time interval. Also, factors related to continuing elevated distress were explored.

METHODS

Breast cancer survivors, 1-5 years after chemotherapy completion, filled in the Dutch Distress Thermometer/Problem List (DT/PL) and questions on background characteristics at study inclusion (T1). DT/PL responses and health care use were discussed during semi-structured interviews. One year later, re-assessment took place (T2). The data were analyzed by descriptive and univariate analyses. Continuing elevated distress was defined as a DT score ≥ 5 at T1 and T2.

RESULTS

Seventy-three survivors completed all questionnaires (response = 84.6%). Eighteen (25%) experienced continuing elevated distress. Fatigue (T1 N = 48 (66%); T2 N = 41 (56%)) and lack of physical fitness (T1 N = 44 (60%); T2 N = 36 (49%)) were most often reported. Time since diagnosis, health care use, and practical, social, emotional and physical problems were significantly associated with continuing elevated distress. Between diagnosis and T1, N = 49(67%) used supportive healthcare services, mostly a psychologist and/or a physical/lymphedema therapist, and between T1 and T2, 39 (53%) did. At T1, 8 (11%) expressed a referral wish and at T2, 11 (16%) did.

CONCLUSIONS

Screening and management of distress, problems, and referral wish are important, even years after chemotherapy completion as a substantial proportion of breast cancer survivors continue to report elevated distress and problems. Special attention should be paid to survivors reporting physical problems, especially fatigue and lack of physical fitness, since these problems are most strongly related to continuing elevated distress.

Visual and quantitative evaluation of [18F]FES and [18F]FDHT PET in patients with metastatic breast cancer: an interobserver variability study

Purpose

Correct identification of tumour receptor status is important for treatment decisions in breast cancer. [¹⁸F]FES PET and [¹⁸F]FDHT PET allow non-invasive assessment of the oestrogen (ER) and androgen receptor (AR) status of individual lesions within a patient. Despite standardised analysis techniques, interobserver variability can significantly affect the interpretation of PET results and thus clinical applicability. The purpose of this study was to determine visual and quantitative interobserver variability of [¹⁸F]FES PET and [¹⁸F]FDHT PET interpretation in patients with metastatic breast cancer.

Methods

In this prospective, two-centre study, patients with ER-positive metastatic breast cancer underwent both [¹⁸F]FES and [¹⁸F]FDHT PET/CT. In total, 120 lesions were identified in 10 patients with either conventional imaging (bone scan or lesions > 1 cm on high-resolution CT, n = 69) or only with [¹⁸F]FES and [¹⁸F]FDHT PET (n = 51). All lesions were scored visually and quantitatively by two independent observers. A visually PET-positive lesion was defined as uptake above background. For quantification, we used standardised uptake values (SUV): SUV_max, SUV_peak and SUV_mean.

Results

Visual analysis showed an absolute positive and negative interobserver agreement for [¹⁸F]FES PET of 84% and 83%, respectively (kappa = 0.67, 95% CI 0.48–0.87), and 49% and 74% for [¹⁸F]FDHT PET, respectively (kappa = 0.23, 95% CI − 0.04–0.49). Intraclass correlation coefficients (ICC) for quantification of SUV_max, SUV_peak and SUV_mean were 0.98 (95% CI 0.96–0.98), 0.97 (95% CI 0.96–0.98) and 0.89 (95% CI 0.83–0.92) for [¹⁸F]FES, and 0.78 (95% CI 0.66–0.85), 0.76 (95% CI 0.63–0.84) and 0.75 (95% CI 0.62–0.84) for [¹⁸F]FDHT, respectively.

Conclusion

Visual and quantitative evaluation of [¹⁸F]FES PET showed high interobserver agreement. These results support the use of [¹⁸F]FES PET in clinical practice. In contrast, visual agreement for [¹⁸F]FDHT PET was relatively low due to low tumour-background ratios, but quantitative agreement was good. This underscores the relevance of quantitative analysis of [¹⁸F]FDHT PET in breast cancer.

Trial registration

ClinicalTrials.gov, NCT01988324. Registered 20 November 2013, https://clinicaltrials.gov/ct2/show/NCT01988324?term=FDHT+PET&draw=1&rank=2.

Abstract OT1-01-05: AIPAC (Active Immunotherapy PAClitaxel): A randomized, double blind, placebo controlled, multinational phase IIb trial evaluating the efficacy of eftilagimod alpha (a soluble LAG-3 fusion protein) in combination with paclitaxel in hormone receptor positive metastatic breast cancer

Background: Eftilagimod alpha (efti, previously IMP321) is a recombinant LAG-3Ig fusion protein that binds to MHC class II and mediates antigen-presenting cell (APC) activation followed by CD8 T-cell activation. Efti may lead to the activation of the dendritic cell network and to a strong anti-tumor CD8 T cell response when injected s.c. after chemotherapy at a time when these APC are loaded with tumor antigens. AIPAC (Active Immunotherapy PAClitaxel; NCT02614833) is a Phase IIb trial in hormone receptor (HR)-positive metastatic breast carcinoma patients receiving efti or placebo as adjunctive to weekly paclitaxel as a first-line chemotherapy. The randomized double blinded part (stage 2) has finished recruitment in June 2019. Primary analysis is expected Q1 2020.

Methods: This clinical trial is a placebo-controlled, double-blind, 1:1 randomized Phase IIb study aimed to enrol 226 patients at multiple centres across 7 different European countries. Patients with metastatic, HR-positive breast adenocarcinoma receiving first line chemotherapy with weekly paclitaxel and with measurable disease according to RECIST 1.1 are eligible. Patients suitable for Her2/neu targeted therapy are excluded from the trial. In the first treatment phase, paclitaxel (80 mg/m² IV at D1, D8, D15 plus efti (30 mg s.c.) or placebo at D2, D16 will be administered for 6 cycles (1 cycle = 4 weeks). This is followed by a maintenance phase in which stable or responding patients will receive efti or placebo for up to additional 52 weeks (12 injections). The primary endpoint is progression-free survival (PFS) by blinded independent central imaging review. Secondary endpoints include PFS by local assessment, overall survival, tumor response according to RECIST 1.1., time to and duration of response, duration of stable disease and quality of life.

Citation Format: Luc Dirix, Hans Wildiers, Manon T Huizing, Eveline De Cuypere, Carolina P Schröder, Anne C Armstrong, Jans Huober, Frederik Marmé, Andreas Schneeweiss, Sarah Khan, Fréderic Triebel. AIPAC (Active Immunotherapy PAClitaxel): A randomized, double blind, placebo controlled, multinational phase IIb trial evaluating the efficacy of eftilagimod alpha (a soluble LAG-3 fusion protein) in combination with paclitaxel in hormone receptor positive metastatic breast cancer [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr OT1-01-05.

Enhanced pulmonary uptake on 18F-FES-PET/CT scans after irradiation of the thoracic area: related to fibrosis?

Rationale

The use of 16α-[¹⁸F]fluoro-17β-estradiol (FES) positron emission tomography (PET) in clinical dilemmas and for therapy decision-making in lesions expressing estrogen receptors is growing. However, on a considerable number of FES PET scans, previously performed in a research and clinical setting in our institution, FES uptake was noticed in the lungs without an oncologic substrate. We hypothesized that this uptake was related to pulmonary fibrosis as a result of radiation therapy. This descriptive study therefore aimed to investigate whether radiation therapy in the thoracic area is possibly related to enhanced pulmonary, non-tumor FES uptake.

Methods

All FES-PET/CT scans performed in our institution from 2008 to 2017 were retrospectively analyzed. Scans from patients who had received irradiation in the thoracic area prior to the scan were compared to scans of patients who had never received irradiation in the thoracic area. The primary outcome was the presence of enhanced non-tumor FES uptake in the lungs, defined as visually increased FES uptake in the absence of an oncologic substrate on the concordant (contrast-enhanced) CT scan. All CT scans were evaluated for the presence of fibrosis or oncologic substrates.

Results

A total of 108 scans were analyzed: 70 scans of patients with previous irradiation in the thoracic area and 38 of patients without. Enhanced non-tumor FES uptake in the lungs was observed in 39/70 irradiated patients (56%), versus in 9/38 (24%) of non-irradiated patients. Fibrosis was present in 37 of the 48 patients with enhanced non-tumor FES uptake (77%), versus in 15 out of 60 (25%) patients without enhanced non-tumor uptake, irrespective of radiotherapy (p < 0.001).

Conclusion

After irradiation of the thorax, enhanced non-tumor uptake on FES-PET can be observed in the radiation field in a significant proportion of patients. This seems to be related to fibrosis. When observing enhanced FES uptake in the lungs, this should not be interpreted as metastases. Information on recent radiation therapy or history of pulmonary fibrosis should therefore be taken into consideration.

Consideration of breast cancer subtype in targeting the androgen receptor

The androgen receptor (AR) is a drug target in breast cancer, and AR-targeted therapies have induced tumor responses in breast cancer patients. In this review, we summarized the role of AR in breast cancer based on preclinical and clinical data. Response to AR-targeted therapies in unselected breast cancer populations is relatively low. Preclinical and clinical data show that AR antagonists might have a role in estrogen receptor (ER)-negative/AR-positive tumors. The prognostic value of AR for patients remains uncertain due to the use of various antibodies and cut-off values for immunohistochemical assessment. To get more insight into the role of AR in breast cancer, we additionally performed a retrospective pooled analysis to determine the prognostic value of the AR using mRNA profiles of 7270 primary breast tumors. Our analysis shows that a higher AR mRNA level is associated with improved disease outcome in patients with ER-positive/human epidermal growth factor receptor 2 (HER2)-negative tumors, but with worse disease outcome in HER2-positive subgroups. In conclusion, next to AR expression, incorporation of additional tumor characteristics will potentially make AR targeting a more valuable therapeutic strategy in breast cancer.

89Zr-atezolizumab imaging as a non-invasive approach to assess clinical response to PD-L1 blockade in cancer

Programmed cell death protein-1/ligand-1 (PD-1/PD-L1) blockade is effective in a subset of patients with several tumor types, but predicting patient benefit using approved diagnostics is inexact, as some patients with PD-L1-negative tumors also show clinical benefit^1,2. Moreover, all biopsy-based tests are subject to the errors and limitations of invasive tissue collection^3-11. Preclinical studies of positron-emission tomography (PET) imaging with antibodies to PD-L1 suggested that this imaging method might be an approach to selecting patients^12,13. Such a technique, however, requires substantial clinical development and validation. Here we present the initial results from a first-in-human study to assess the feasibility of imaging with zirconium-89-labeled atezolizumab (anti-PD-L1), including biodistribution, and secondly test its potential to predict response to PD-L1 blockade (ClinicalTrials.gov identifiers NCT02453984 and NCT02478099). We imaged 22 patients across three tumor types before the start of atezolizumab therapy. The PET signal, a function of tracer exposure and target expression, was high in lymphoid tissues and at sites of inflammation. In tumors, uptake was generally high but heterogeneous, varying within and among lesions, patients, and tumor types. Intriguingly, clinical responses in our patients were better correlated with pretreatment PET signal than with immunohistochemistry- or RNA-sequencing-based predictive biomarkers, encouraging further development of molecular PET imaging for assessment of PD-L1 status and clinical response prediction.

Comparative biodistribution analysis across four different 89Zr-monoclonal antibody tracers-The first step towards an imaging warehouse

Rationale: Knowledge on monoclonal antibody biodistribution in healthy tissues in humans can support clinical drug development. Molecular imaging with positron emission tomography (PET) can yield information in this setting. However, recent imaging studies have analyzed the behavior of single antibodies only, neglecting comparison across different antibodies. Methods: We compared the distribution of four ⁸⁹Zr-labeled antibodies in healthy tissue in a retrospective analysis based on the recently published harmonization protocol for ⁸⁹Zr-tracers and our delineation protocol. Results: The biodistribution patterns of ⁸⁹Zr-lumretuzumab, ⁸⁹Zr-MMOT0530A, ⁸⁹Zr-bevacizumab and ⁸⁹Zr-trastuzumab on day 4 after tracer injection were largely similar. The highest tracer concentration was seen in healthy liver, spleen, kidney and intestines. About one-third of the injected tracer dose was found in the circulation, up to 15% in the liver and only 4% in the spleen and kidney. Lower tracer concentration was seen in bone marrow, lung, compact bone, muscle, fat and the brain. Despite low tracer accumulation per gram of tissue, large-volume tissues, especially fat, can influence overall distribution: On average, 5-7% of the injected tracer dose accumulated in fat, with a peak of 19% in a patient with morbid obesity. Conclusion: The similar biodistribution of the four antibodies is probably based on their similar molecular structure, binding characteristics and similar metabolic pathways. These data provide a basis for a prospectively growing, online accessible warehouse of molecular imaging data, which enables researchers to increase and exchange knowledge on whole body drug distribution and potentially supports drug development decisions.

89Zr-trastuzumab PET supports clinical decision making in breast cancer patients, when HER2 status cannot be determined by standard work up

Background

Up-to-date information on human epidermal growth factor receptor 2 (HER2) status in breast cancer (BC) is important, as expression can vary during the course of the disease, necessitating anti-HER2 therapy adjustments. Repeat biopsies, however, are not always possible. In this feasibility trial we assessed whether ⁸⁹Zr-trastuzumab PET could support diagnostic understanding and aid clinical decision making, when HER2 status could not be determined by standard work up. Additionally, HER2 status on circulating tumour cells (CTCs) was assessed.

Patients and methods

⁸⁹Zr-trastuzumab PET was performed in patients if disease HER2 status remained unclear after standard work up (bone scan, ¹⁸F-FDG PET, CT and if feasible a biopsy). PET result and central pathologic revision of available tumour biopsies were reported to the referring physician. CTC HER2 status prior to PET was evaluated afterwards and therefore not reported. Diagnostic understanding and treatment decision questionnaires were completed by the referring physicians before, directly after and ≥ 3 months after ⁸⁹Zr-trastuzumab PET.

Results

Twenty patients were enrolled: 8 with two primary cancers (HER2-positive and HER2-negative BC or BC and non-BC), 7 with metastases inaccessible for biopsy, 4 with prior HER2-positive and -negative metastases and 1 with primary BC with equivocal HER2 status. ⁸⁹Zr-trastuzumab PET was positive in 12 patients, negative in 7 and equivocal in 1 patient. In 15/20 patients, ⁸⁹Zr-trastuzumab PET supported treatment decision. The scan altered treatment of 8 patients, increased physicians’ confidence without affecting treatment in 10, and improved physicians’ disease understanding in 18 patients. In 10/20 patients CTCs were detected; 6/10 showed HER2 expression. CTC HER2 status was not correlated to ⁸⁹Zr-trastuzumab PET result or treatment decision.

Conclusion

⁸⁹Zr-trastuzumab PET supports clinical decision making when HER2 status cannot be determined by standard work up. The impact of CTC HER2 status needs to be further explored.

Electronic supplementary material

The online version of this article (10.1007/s00259-018-4099-8) contains supplementary material, which is available to authorized users.

Abstract PD2-12: Molecular imaging for early identification of patients who benefit from palbociclib in addition to letrozole

Palbociclib plus letrozole has improved both progression free survival and overall response rate in metastatic breast cancer (MBC) patients. For response to palbociclib, the best biomarker is ER expression. 16α-[18F]Fluoro-17β-estradiol (FES) -PET allows whole body ER level assessment, and provides insight in the heterogeneity of ER expression throughout the body. We hypothesized that lesions with low uptake on FES-PET are unlikely to respond to letrozole plus palbociclib. METHODS: Post-menopausal women with ER positive MBC were eligible for this pilot study. All patients were staged with fludeoxyglucose (FDG)-PET and CT scan, and in addition a FES-PET was performed at baseline. After 8 weeks treatment an FDG-PET/CT was used for response evaluation. The primary endpoint was the relation between standard uptake value (SUV) per lesion on FES-PET to response, as measured by RECIST 1.1 criteria in case of measurable disease. In case of non-measurable bone lesions, progression was defined as an increase in SUV on FDG-PET of more than 30% per lesion compared to baseline (based on PERCIST). RESULTS: 15 patients were included of which 14 were evaluable for primary endpoint. Mean age was 50 years (range 35-76). Median number of prior therapies was 1. A total of 280 lesions were detected on conventional imaging of which 50 showed low uptake (SUV&lt;1.5) on FES-PET. 29/50 low uptake lesions showed progression based on diagnostic CT (n=9) or FDG PET (n=20). In contrast, 28/230 FES positive lesions showed progression.

 ResponseStable diseaseProgression FES uptake &gt;1.51089428230FES uptake &lt;1.57142950 11510857280

DISCUSSION: this pilot trial indicates negative predictive value of low FES uptake for response to letrozol plus palbociclib in ER positive MBC. The FES-PET may therefore be a biomarker for response for this combination treatment. This will have to be explored further in future clinical trials.

Citation Format: Venema CM, de Vries EFJ, Glaudemans AWJM, Hospers GAP, Schröder CP. Molecular imaging for early identification of patients who benefit from palbociclib in addition to letrozole [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr PD2-12.

Abstract P5-23-01: Clinical and biological characterization of male breast cancer (BC) EORTC 10085/TBCRC 029/BOOG 2013-02/BIG 2-07: Baseline results from the prospective registry

BACKGROUND: Through the International Male Breast Cancer Program, a prospective registry for male BC was created with the goals of evaluating 1) the clinical and biological features of this disease and 2) assessing feasibility of a prospective therapeutic clinical trial.

METHODS: All men, with any stage histologically proven invasive breast cancer, age 3 18 years, and newly presenting at the participating institutions (within 3 months prior) were eligible. Patients were enrolled for 30 months after activation of the first center, through February 2017. Per the study design, if &lt;100 men enrolled, the study would be considered a failure and therapeutic trials would not be pursued through this network. Epidemiologic data, staging, pathologic features, and BRCA status were collected. Treatment and outcome data collection is ongoing. Optional collection of FFPE tumor samples, blood, and QOL were performed in the US, the Netherlands, and Latin America. Clinical database lock for this report was May 30, 2017. We currently report patient and disease characteristics and will update with patterns of treatment for the presentation. Outcomes and biological samples will be analyzed in the future.

RESULTS: 557 patients were enrolled: 75% in Europe, 20% in United States, 5% in other countries. 6.3% of patients had missing forms. Median age was 67 years (range 26-92). 93% were diagnosed 2010-2017. Among patients with complete data, 79% presented with a breast mass. 88% were M0 and 12% M1. Among M0 patients: 47%, 39%, 2%, and 11% had T1, T2, T3, and T4 disease respectively; 52% were N0. Overall, 98% had ER+ disease and 11% had HER2+ cancer. 14% had grade 1, 56% had grade 2, and 30% had grade 3 tumors. Among 112 men who underwent BRCA1 testing, 1 was positive. Among 118 men who had BRCA2 testing, 18 (15%) were positive. 21% of men had prior or concurrent malignancies, with the following most common sites: prostate, non-melanoma skin, colorectal, and melanoma. The prevalence of previously identified possible risk factors for male breast cancer were: overweight/obesity (72%), former/current smoker (51%), current alcohol 31 drink daily (41%), family history of breast cancer (35%), gynecomastia (16%), history radiation exposure (8%), use of anti-androgens (1%), and use of estrogens (1%).

CONCLUSION: Through an international collaborative effort, we were able to prospectively accrue 557 patients to a male breast cancer registry. These results demonstrate feasibility of pursuing a therapeutic clinical trial in men with breast cancer. In addition, this study shows the relatively low uptake of BRCA testing, high rates of concurrent/prior malignancy, and the rates of potentially modifiable risk factors in this patient population.

Funding from Breast Cancer Research Foundation, Susan G. Komen, Dutch Pink Ribbon Foundation, Swedish Breast Cancer Association (BRO) and EBCC Council.

Citation Format: Giordano SH, Schröder CP, Poncet C, van Leeuwen-Stok E, Linderholm B, Abreu MH, Rubio I, Van Poznak C, Morganstern D, Cameron D, Vleugel MM, Smilde TJ, Bozovic-Spasojevic I, Korde L, Russell NS, den Hoed IDM, Honkoop AH, van der Velden AWG, van 't Riet M, Dijkstra N, Bogler O, Goulioti T, Hilsenbeck S, Ruddy KJ, Wolff A, van Deurzen CHM, Martens J, Bartlett JMS, Aalders K, Tryfonidis K, Cardoso F. Clinical and biological characterization of male breast cancer (BC) EORTC 10085/TBCRC 029/BOOG 2013-02/BIG 2-07: Baseline results from the prospective registry [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P5-23-01.

Abstract P5-03-06: Clinical value of 89Zr-trastuzumab PET in HER2-positive breast cancer patients with a clinical dilemma

Background: Information on human epidermal growth factor receptor 2 (HER2) is essential for management of metastatic breast cancer (mBC). In patients suspected of HER2-positive mBC, standard work up may fail to clarify whole body HER2 status. We aimed to assess whether 89Zr-trastuzumab PET can support treatment decisions in patients posing this clinical dilemma.

Methods: 89Zr-trastuzumab PET was performed as described earlier (Gaykema et al, Clin Cancer Res 2014) in patients in whom standard work up with bone scan, FDG PET, CT and if feasible a biopsy, failed to evaluate HER2 status of their disease. 89Zr-trastuzumab PET was defined positive, when at least a dominant part of the tumor load showed substantial tracer uptake (Gebhart et al, Ann Oncol 2015), when tumor tracer uptake in single lesions (except brain) was ≥ normal liver uptake or when brain metastases had a tracer uptake &gt; background. Circulating tumor cell (CTC) analysis prior to tracer injectionwas performed using the CellSearch System (Janssen Diagnostics LLC) and CTC HER2 status was assessed immunofluorescently. Questionnaires about treatment decisions were completed before, directly after and ≥3 months after 89Zr-trastuzumab PET.

Results: Twenty patients were enrolled: 8 with two primary cancers (HER2-positive and HER2-negative BC or BC and non-BC), 7 with metastases inaccessible for biopsy, 4 with prior HER2-positive and HER2-negative metastases, 1 with primary BC with equivocal HER2 status (average 4.23 HER2 gene copies/nucleus). 89Zr-trastuzumab PET was positive in 12 patients, negative in 7 and equivocal in one patient. In 15/20 patients 89Zr-trastuzumab PET supported treatment decision. The scan altered treatment of 8 patients, increased physicians' confidence without affecting treatment in 10, and improved physicians' understanding of disease in 18 patients. Ten patients had 1-99 CTCs, 6 with HER2 expression. There was no correlation between HER2 expression by CTCs and 89Zr-trastuzumab PET results or subsequent treatment decision.

Conclusion: 89Zr-trastuzumab PET, but not CTC analysis, supports clinical decision making in BC patients in whom standard work up fails to evaluate HER2 status. (Funded by the Dutch A Sister's Hope).

Citation Format: Schröder CP, Bensch F, Brouwers AH, Lub-de Hooge MN, de Jong JR, van der Vegt B, Sleijfer S, de Vries EG. Clinical value of 89Zr-trastuzumab PET in HER2-positive breast cancer patients with a clinical dilemma [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P5-03-06.

Translation of New Molecular Imaging Approaches to the Clinical Setting: Bridging the Gap to Implementation

Molecular imaging with PET is a rapidly emerging technique. In breast cancer patients, more than 45 different PET tracers have been or are presently being tested. With a good rationale, after development of the tracer and proven feasibility, it is of interest to evaluate whether there is a potential meaningful role for the tracer in the clinical setting-such as in staging, in the (early) prediction of a treatment response, or in supporting drug choices. So far, only (18)F-FDG PET has been incorporated into breast cancer guidelines. For proof of the clinical relevance of tracers, especially for analysis in a multicenter setting, standardization of the technology and access to the novel PET tracer are required. However, resources for PET implementation research are limited. Therefore, next to randomized studies, novel approaches are required for proving the clinical value of PET tracers with the smallest possible number of patients. The aim of this review is to describe the process of the development of PET tracers and the level of evidence needed for the use of these tracers in breast cancer. Several breast cancer trials have been performed with the PET tracers (18)F-FDG, 3'-deoxy-3'-(18)F-fluorothymidine ((18)F-FLT), and (18)F-fluoroestradiol ((18)F-FES). We studied them to learn lessons for the implementation of novel tracers. After defining the gap between a good rationale for a tracer and implementation in the clinical setting, we propose solutions to fill the gap to try to bring more PET tracers to daily clinical practice.

Abstract P5-01-07: Radiotherapy may induce enhanced uptake on 18F-fluoroestradiol PET scans

Introduction: Whole body imaging of 18F-fluoroestradiol (FES) uptake combined with positron emission tomography (PET) has been applied for diagnosis and prediction of therapy response in estrogen receptor (ER) positive breast cancer patients. A maximal standardized uptake value (SUVmax) of 1.5 has previously been defined as the optimal threshold for FES uptake to differentiate between ER-positive and negative tumor lesions. FES uptake in healthy tissue differs per anatomic site and can be influenced by extrinsic factors. Previous FES PET studies have suggested that radiotherapy (RTx) may cause heterogeneous enhanced uptake in lungs. The cause of this uptake has not been elucidated yet. This is an exploratory study to evaluate whether patients with RTx prior to FES PET show enhanced FES uptake in tissues in the irradiation field.

Methods: Our FES PET database was screened between 2009 and June 2015 for patients who had RTx ≤6 months before FES PET, independent of location of RTx. Irradiation fields were reconstructed and fused with the FES PET scan. The main outcome was the presence of enhanced FES uptake, defined as visually increased FES uptake above background with a SUVmax &gt;1.5 in the irradiation field in the absence of an oncologic substrate on the concordant (contrast enhanced) CT scan.

Results: A total of 133 patients were identified in the database; 29 were eligible for the study. Mean age at the first FES PET scan was 57 (SD 9) years. 28/29 patients had breast cancer, 2/28 had a concurrent other malignancy. Seventeen patients (59%) showed enhanced uptake in the RTx field. 15/17 patients were irradiated in the thoracic area, and 2/17 at the hip. Enhanced uptake was mostly located at the dorsomedial side of the lungs, or subcutaneously after thoracic- or hip RTx, respectively. Patients with normal FES uptake in the radiation field were irradiated in the pelvic/lumbal spine area (n=5), hip (n=3) or thorax (n=4). Time range between RTx and FES PET did not differ between patients with and without enhanced FES uptake (mean 50.9 days [range 0-156] vs. mean 56.8 days [range 0-178]). Systemic treatment at the time of FES PET did not differ between the patients with and without enhanced uptake. Radiation dosage in gray (Gy) was related to enhanced FES uptake, after RTx in the thoracic area or at the hip.

Conclusion: RTx can induce enhanced uptake in the irradiation field on the FES PET scan in part of the patients. Irradiation-induced FES uptake most frequently occurs in lung tissue. Therefore, physicians should keep the possibility of radiation-induced aspecific enhanced tracer uptake in mind, when interpreting FES PET scan of patients that have recently received RTx.

Citation Format: Venema CM, van der Veen SJ, Glaudemans AWJM, Schröder CP, de Vries EFJ, Hospers GAP. Radiotherapy may induce enhanced uptake on 18F-fluoroestradiol PET scans. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P5-01-07.

Abstract P6-08-01: Inverse relationships between high somatic copy number load and immune phenotypes in breast cancer

Introduction

Currently, there is no clear biomarker to predict which breast cancer patient may benefit from immunotherapy. High somatic point mutational load is thought to lead to immune activation and CD8+ T cell activation and infiltration. In addition, pre-existing CD8+ T cells distinctly located at the invasive tumor margin are associated with expression of the PD-1/PD-L1 immune inhibitory axis and may predict response to PD-1 targeted therapy. However, breast tumors are considered copy number-driven rather than mutational-driven cancers. Therefore, in order to identify which breast cancer patients may potentially benefit from immunotherapy, we investigated relations between copy number load and CD8+ T cell abundance, immune pathways and immune activation scores in a large set of publically available breast cancer expression profiles.

Methods

Functional genomic mRNA-profiling (Fehrmann et al., Nat Genet, 2015) was used to capture the downstream effect of somatic copy number alterations on gene expression levels. This method allowed using gene expression profiles to quantify somatic copy number load occurring in tumor samples in a univariate measurement called the copy number load index (CNL-index). Immune activation scores were calculated according to two known gene immune signatures (Teschendorff et al., Genome Biol, 2007 and Desmedt et al., Clin Cancer Res, 2008). Cibersort (Newman et al., Nat Methods, 2015) was applied to estimate CD8+ T cell abundance. Publicly available gene expression profiles of 7,270 primary breast cancer samples were used. The relation between CNL-index, immune activation scores and disease-free survival (DFS), defined as time from diagnosis until distant metastasis development, was assessed by multivariate cox-regression analysis including age, ER and HER2 status, tumor size, lymph node involvement, tumor grade and treatment regimen. Gene set enrichment analysis (GSEA) was applied to assess relations between immune pathways and CNL-index.

Results

In primary breast cancer, low CNL-index was found in 1,796 samples (24.7%) versus 5,474 samples with a high CNL-index (75.3%). Higher CNL-index was correlated with shorter DFS (HR 2.51, P = 1.6x10-4), whereas higher immune activation scores were associated with prolonged DFS (HR 0.199, P = 0.003 and HR 0.347, P = 0.017). CD8+ T cell abundance was negatively correlated with the CNL-index (Spearman R = -0.14, P = 8.11x10-34). GSEA showed enrichment of immune pathways amongst genes that negatively correlated with CNL-index. Subset analysis in 1,555 TNBC samples showed low CNL-index in 287 samples (18.5%) versus high CNL-index in 1,268 samples (81.5%). Similar to the entire breast cancer set, CD8+ T cell abundance and CNL-index were negatively correlated in TNBC (Spearman R = -0.11, P = 4.11x10-05). Immune pathway enrichment in genes in TNBC also negatively correlated to CNL-index.

Conclusion

High CNL-index (i.e. high copy number load) is inversely related to immunoactivation, immune pathways and CD8+ T cell abundance. This implies that in breast cancer, tumors with low CNL-index may be intrinsically sensitive to immune modulation, which warrants further confirmation in prospective trials.

This research was supported by Dutch Cancer Society Grants RUG 2010-4739 and RUG 2013-5960.

Citation Format: Bense RD, van der Vegt B, de Vries EGE, van Vugt MATM, Schröder CP, Fehrmann RSN. Inverse relationships between high somatic copy number load and immune phenotypes in breast cancer. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P6-08-01.

Molecular imaging as a tool to investigate heterogeneity of advanced HER2-positive breast cancer and to predict patient outcome under trastuzumab emtansine (T-DM1): the ZEPHIR trial

BACKGROUND

Only human epidermal growth factor receptor (HER)2 status determined by immunohistochemistry (IHC) and fluorescence in situ hybridization (FISH) has been validated to predict efficacy of HER2-targeting antibody-drug-conjugate trastuzumab emtansine (T-DM1). We propose molecular imaging to explore intra-/interpatient heterogeneity in HER2 mapping of metastatic disease and to identify patients unlikely to benefit from T-DM1.

PATIENTS AND METHODS

HER2-positive mBC patients with IHC3+ or FISH ≥ 2.2 scheduled for T-DM1 underwent a pretreatment HER2-positron emission tomography (PET)/computed tomography (CT) with (89)Zr-trastuzumab. [(18)F]2-fluoro-2-deoxy-D-glucose (FDG)-PET/CT was performed at baseline and before T-DM1 cycle 2. Patients were grouped into four HER2-PET/CT patterns according to the proportion of FDG-avid tumor load showing relevant (89)Zr-trastuzumab uptake (>blood pool activity): patterns A and B were considered positive (>50% or all of the tumor load 'positive'); patterns C and D were considered negative (>50% or all of the tumor load 'negative'). Early FDG-PET/CT was defined as nonresponding when >50% of the tumor load showed no significant reduction of FDG uptake (<15%). Negative (NPV) and positive predictive values (PPV) of HER2-PET/CT, early FDG response and their combination were assessed to predict morphological response (RECIST 1.1) after three T-DM1 cycles and time-to-treatment failure (TTF).

RESULTS

In the 56 patients analyzed, 29% had negative HER2-PET/CT while intrapatient heterogeneity (patterns B and C) was found in 46% of patients. Compared with RECIST1.1, respective NPV/PPV for HER2-PET/CT were 88%/72% and 83%/96% for early FDG-PET/CT. Combining HER2-PET/CT and FDG-PET/CT accurately predicted morphological response (PPV and NPV: 100%) and discriminated patients with a median TTF of only 2.8 months [n = 12, 95% confidence interval (CI) 1.4-7.6] from those with a TTF of 15 months (n = 25, 95% CI 9.7-not calculable).

CONCLUSIONS

Pretreatment imaging of HER2 targeting, combined with early metabolic response assessment holds great promise for improving the understanding of tumor heterogeneity in mBC and for selecting patients who will/will not benefit from T-DM1.

CLINICALTRIALSGOV IDENTIFIER

NCT01565200.

Impact of primary local treatment on the development of distant metastases or death through locoregional recurrence in young breast cancer patients

In this study, we tested the hypothesis whether breast conserving therapy (BCT) compared with mastectomy is associated with a negative outcome in terms of distant metastases or death (DMD) and investigated the relation between locoregional recurrence (LRR) and DMD in young breast cancer (BC) patients. This study included a consecutive series of 536 patients ≤40 years of age at diagnosis with pathological T1N0-3M0 BC, treated between 1989 and 2005. A multistate survival model was used to evaluate the influences of local treatment and LRR on DMD, adjusted for potential prognostic factors. Patients were treated with mastectomy (N = 213) or BCT (N = 323). Median age at diagnosis was 36.3 years, with a median follow-up of 9.0 years. The 10-year actuarial cumulative incidence of DMD was 30.6 % after mastectomy and 26.3 % after BCT (P = 0.04). In total, 81 (15 %) LRRs were observed. After BCT, patients had a threefold higher risk of LRR than after mastectomy (HR 2.9; 95 % CI 1.6-5.3). Patients with LRR had a higher risk of DMD compared with patients without LRR (HR 5.5; 95 % CI 2.1-14.5). However, BCT was not negatively associated with DMD-after-LRR (HR 0.47; 95 % CI 0.2-1.1, BCT vs mastectomy). In conclusion, although LRR significantly affected DMD, the increased risk of LRR after BCT compared with mastectomy did not lead to a worse DMD outcome in BC patients ≤40 years of age.

Bevacizumab-induced normalization of blood vessels in tumors hampers antibody uptake

In solid tumors, angiogenesis occurs in the setting of a defective vasculature and impaired lymphatic drainage that is associated with increased vascular permeability and enhanced tumor permeability. These universal aspects of the tumor microenvironment can have a marked influence on intratumoral drug delivery that may often be underappreciated. In this study, we investigated the effect of blood vessel normalization in tumors by the antiangiogenic drug bevacizumab on antibody uptake by tumors. In mouse xenograft models of human ovarian and esophageal cancer (SKOV-3 and OE19), we evaluated antibody uptake in tumors by positron emission tomographic imaging 24 and 144 hours after injection of (89)Zr-trastuzumab (SKOV-3 and OE19), (89)Zr-bevacizumab (SKOV-3), or (89)Zr-IgG (SKOV-3) before or after treatment with bevacizumab. Intratumor distribution was assessed by fluorescence microscopy along with mean vessel density (MVD) and vessel normalization. Notably, bevacizumab treatment decreased tumor uptake and intratumoral accumulation compared with baseline in the tumor models relative to controls. Bevacizumab treatment also reduced MVD in tumors and increased vessel pericyte coverage. These findings are clinically important, suggesting caution in designing combinatorial trials with therapeutic antibodies due to a possible reduction in tumoral accumulation that may be caused by bevacizumab cotreatment.

Lapatinib and 17AAG reduce 89Zr-trastuzumab-F(ab')2 uptake in SKBR3 tumor xenografts

Human epidermal growth factor receptor-2 (HER2) directed therapy potentially can be improved by insight in drug effects on HER2 expression. This study evaluates the effects of the EGFR/HER2 tyrosine kinase inhibitor lapatinib, the heat shock protein-90 inhibitor 17AAG, and their combination, on HER2 expression with in vivo HER2-PET imaging. Lapatinib and 17AAG effects on EGFR and HER2 membrane expression were determined in vitro using flow cytometry of human SKBR3 tumor cells. Effect of lapatinib on HER2 internalization was studied in vitro by (89)Zr-trastuzumab-F(ab')(2) internalization. For in vivo evaluation, (89)Zr-trastuzumab-F(ab')(2) μPET imaging was performed two times with a 7 day interval. Lapatinib was administered for 6 days, starting 1 day after the baseline scan. 17AAG was given 1 day before the second (89)Zr-trastuzumab-F(ab')(2) injection. Imaging data were compared with ex vivo biodistribution analysis and HER2 immunohistochemical staining. 17AAG treatment lowered EGFR expression by 41% (P = 0.016) and HER2 by 76% (P = 0.022). EGFR/HER2 downregulation by 17AAG was inhibited by lapatinib pretreatment. Lapatinib reduced internalization of (89)Zr-trastuzumab-F(ab')(2) with 25% (P = 0.0022). (89)Zr-trastuzumab-F(ab')(2) tumor to blood ratio was lowered 32% by lapatinib (P = 0.00004), 34% by 17AAG (P = 0.0022) and even 53% by the combination (P = 0.011). Lapatinib inhibits HER2 internalization and 17AAG lowers HER2 membrane expression. Both drugs reduce (89)Zr-trastuzumab-F(ab')(2) tumor uptake. Based on our findings, supported by previous preclinical data indicating the antitumor potency of lapatinib in combination with HSP90 inhibition, combination of these drugs deserves further investigation.

Lapatinib: clinical benefit in patients with HER 2-positive advanced breast cancer

BACKGROUND

Lapatinib, a tyrosine kinase inhibitor of human epidermal growth factor receptor 2 (HER2), has shown activity in combination with capecitabine in patients with HER2-positive advanced breast cancer progressive on standard treatment regimens. We present results on preapproval drug access for this combination in such patients occurring in the general oncology practice in the Netherlands.

METHODS

Patients with HER2-positive advanced breast cancer progressive on schedules containing anthracyclines, taxanes, and trastuzumab were eligible. Brain metastases were allowed if stable. Lapatinib 1250 mg÷day was given continuously in combination with capecitabine 1000 mg÷m2 twice daily for two weeks in a three-week cycle. Efficacy was assessed by use of response evaluation criteria in solid tumours version 1.0. Progression-free survival (PFS) and overall survival (OS) were calculated.

RESULTS

Eighty-three patients were enrolled from January 2007 until July 2008. The combination was generally well tolerated and the most common drug-related serious adverse events were nausea and÷or vomiting (5%) and diarrhoea (2%). Seventy-eight patients were evaluable for response. Clinical benefit (response or stable disease for at least 12 weeks) was observed in 50 patients (64%) of whom 15 had a partial response and 35 stable disease. The median PFS and OS were 17 weeks (95% CI: 13 to 21) and 39 weeks (95% CI: 24 to 54), respectively. For OS, higher Eastern Cooperative Oncology Group (ECOG) status (p=0.016), brain metastases at study entry (p=0.010) and higher number of metastatic sites (p=0.012) were significantly negative predictive factors.

CONCLUSION

In a patient population with heavily pretreated HER2-positive advanced breast cancer lapatinib plus capecitabine was well tolerated and offered clinical benefit.

Molecular imaging of breast cancer

Molecular imaging of breast cancer can potentially be used for breast cancer screening, staging, restaging, response evaluation and guiding therapies. Techniques for molecular breast cancer imaging include magnetic resonance imaging (MRI), optical imaging, and radionuclide imaging with positron emission tomography (PET) or single photon emission computed tomography (SPECT). This review focuses on PET and SPECT imaging which can provide sensitive serial non invasive information of tumor characteristics. Most clinical data are gathered on the visualization of general processes such as glucose metabolism with the PET-tracer [(18)F]fluorodeoxyglucose (FDG) and DNA synthesis with [18F]fluoro-L-thymidine (FLT). Increasingly more breast cancer specific targets are imaged such as the estrogen receptor (ER), growth factors and growth factor receptors. Imaging of the ER with the PET tracer 16-alpha-[(18)F]fluoro-17-beta-estradiol (FES) has shown a good correlation between FES tumor uptake and ER density. (111)In-trastuzumab SPECT to image the human epidermal growth factor receptor 2 (HER2) showed that in most patients with metastatic HER2 overexpressing disease more lesions were detected than with conventional staging procedures. The PET tracer (89)Zr-trastuzumab showed excellent, quantifiable, and specific tumor uptake. (111)In-bevacizumab for SPECT and (89)Zr-bevacizumab for PET-imaging have been developed for vascular endothelial growth factor (VEGF) imaging as an angiogenic marker. Lastly, tracers for the receptors EGFR, IGF-1R, PDGF-betaR and the ligand TGFbeta are under development. Although molecular imaging of breast cancer is still not commonly used in daily clinical practice, its application portfolio is expanding rapidly.

An in vitro model for purging of tumour cells from ovarian tissue

BACKGROUND

Cryopreservation and autografting of ovarian tissue may preserve fertility after cancer treatment, but could be hampered by tumour cell contamination. Epithelial tumour cell lysis can be obtained with cytotoxic T cell retargeting through the bispecific antibody BIS-1, with combined affinity for the T-cell receptor and epithelial glycoprotein-2 (EGP-2). Our aim was to study the concept of tumour cell purging in the setting of a suspension of ovarian tissue.

METHODS

Human ovarian tissue was brought into suspension by mechanical and enzymatic treatment. Cells of the MCF-7 breast cancer cell line and activated human lymphocytes were co- incubated for 4 h with or without BIS-1 and with or without ovarian suspension. After incubation, MCF-7 cell death and cell growth were evaluated by fluorescent cell detection and MTT assay, respectively. Ovarian tissue morphology was evaluated immunohistochemically.

RESULTS

MCF-7 cell death and cell growth inhibition increased with increasing ratios of lymphocytes to MCF-7 cells. BIS-1 addition gave further augmentation, with a maximum depletion of growing MCF-7 cells of 89% (SD 11%) versus without BIS-1, 23% (SD 15%; P < 0.001). Follicles remained morphologically intact.

CONCLUSIONS

Purging of added epithelial tumour cells from ovarian tissue with BIS-1 is possible in vitro. Morphologically, follicles remain intact after this procedure. This method may contribute to safer replacement of ovarian tissue in female cancer survivors.

Telomere length in breast cancer patients before and after chemotherapy with or without stem cell transplantation

High-dose chemotherapy and peripheral blood stem cell transplantation (PBSCT) may accelerate telomere length loss in haematopoietic stem cells. As data including pre-and post-treatment samples are lacking, we studied leukocyte telomere length and telomerase activity before and after treatment in breast cancer patients randomized to receive 5 adjuvant courses FEC (5-FU, epirubicin and cyclophosphamide) (n= 17), or 4 × FEC followed by high-dose cyclophosphamide, thiotepa, carboplatin and autologous PBSCT (n= 16). Haemoglobin, MCV, leukocyte-and platelet numbers were assessed prior to (t₀), 5 months after (t₁) and 9 months after chemotherapy (t₂); these parameters were decreased at t₁ and t₂ compared to t₀(high-dose: all parameters; standard-dose: leukocytes and platelets), and all parameters were lower after high-dose than standard-dose treatment at t₁. Paired individual leukocyte samples of t₀ and t₁ showed telomere length change (determined by telomere restricted fragment (TRF) assay) ranging from +0.8 to –2.2 kb, with a decreased TRF length in 9 patients of both groups. Telomerase activity (determined by TRAP assay) was below detection limit in leukocyte samples of t₀ and t₁. Thus, standard-and high-dose chemotherapy negatively affect haematological reconstitution in this setting. In individual patients, telomere length can be remarkably changed following haematological proliferative stress after treatment. © 2001 Cancer Research Campaign www.bjcancer.com

Purging of epithelial tumor cells from peripheral blood stem cells by means of the bispecific antibody BIS-1

Peripheral blood stem cell (PBSC) support in breast cancer patients allows high-dose chemotherapy, but tumor cell contamination of the PBSCs is a potential source of relapse. Specific carcinoma cell killing can be obtained by retargeting activated T cells with bispecific antibody BIS-1, directed against epithelial glycoprotein-2 and CD3. To purge epithelial tumor cells from the PBSCs of breast cancer patients, activation of T cells in PBSCs and T-cell retargeting by BIS-1 was studied. PBSCs, obtained by leukapheresis after chemotherapy and recombinant human granulocyte colony-stimulating factor, were cultured in the presence of PBS, interleukin-2, OKT3, or interleukin-2/OKT3 for induction of T-cell activation. Subsequently, lysis of epithelial tumor cell lines by activated T cells of PBSCs in the presence or absence of BIS-1 was assessed with the 51Cr-release assay or immunocytochemical staining. The effect on PBSC hematopoietic colony formation (HCF) was evaluated by the granulocyte macrophage colony-stimulating units assay. Prior to activation, PBSCs from breast cancer patients contained higher levels of CD8+ T cells than peripheral blood from healthy volunteers (P < 0.05). The potential of PBSCs to sustain tumor cell lysis was increased after all prior activations and was further enhanced by BIS-1. Maximal BIS-1 effect was observed after OKT3 activation of PBSCs for 72 h (P < 0.0005), inducing a >3 log depletion of tumor cells. HCF was not affected by prior OKT3 activation and/or BIS-1. In conclusion, specific tumor cell lysis by PBSCs can be obtained in vitro by OKT3 activation and BIS-1 retargeting of T cells, without affecting HCF. At present, studies are evaluating this format for future clinical application.