89Zr-pembrolizumab imaging as a non-invasive approach to assess clinical response to PD-1 blockade in cancer.

BACKGROUND: Programmed cell death protein 1 (PD-1) antibody treatment is standard of care for melanoma and non-small-cell lung cancer (NSCLC). Accurately predicting which patients will benefit is currently not possible. Tumor uptake and biodistribution of the PD-1 antibody might play a role. Therefore, we carried out a positron emission tomography (PET) imaging study with zirconium-89 (89Zr)-labeled pembrolizumab before PD-1 antibody treatment. PATIENTS AND METHODS: Patients with advanced or metastatic melanoma or NSCLC received 37 MBq (1 mCi) 89Zr-pembrolizumab (∼2.5 mg antibody) intravenously plus 2.5 or 7.5 mg unlabeled pembrolizumab. After that, up to three PET scans were carried out on days 2, 4, and 7. Next, PD-1 antibody treatment was initiated. 89Zr-pembrolizumab tumor uptake was calculated as maximum standardized uptake value (SUVmax) and expressed as geometric mean. Normal organ uptake was calculated as SUVmean and expressed as a mean. Tumor response was assessed according to (i)RECIST v1.1. RESULTS: Eighteen patients, 11 with melanoma and 7 with NSCLC, were included. The optimal dose was 5 mg pembrolizumab, and the optimal time point for PET scanning was day 7. The tumor SUVmax did not differ between melanoma and NSCLC (4.9 and 6.5, P = 0.49). Tumor 89Zr-pembrolizumab uptake correlated with tumor response (P trend = 0.014) and progression-free (P = 0.0025) and overall survival (P = 0.026). 89Zr-pembrolizumab uptake at 5 mg was highest in the spleen with a mean SUVmean of 5.8 (standard deviation ±1.8). There was also 89Zr-pembrolizumab uptake in Waldeyer's ring, in normal lymph nodes, and at sites of inflammation. CONCLUSION: 89Zr-pembrolizumab uptake in tumor lesions correlated with treatment response and patient survival. 89Zr-pembrolizumab also showed uptake in lymphoid tissues and at sites of inflammation.

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.

Targeting breast cancer through its microenvironment: current status of preclinical and clinical research in finding relevant targets.

It is increasingly evident that not only breast cancer cells, but also the tissue embedding these cells: the tumor microenvironment, plays an important role in tumor progression, metastasis formation and treatment sensitivity. This review focuses on the current knowledge of processes by which the microenvironment affects breast cancer, including formation of the metastatic niche, metabolic stimulation, stimulation of tumor cell migration, immune modulation, angiogenesis and matrix remodeling. The number of drugs targeting key factors in these processes is expanding, and the available clinical data is increasing. Therefore current strategies for intervention and prediction of treatment response are outlined. At present, targeting the formation of the metastatic niche and metabolic stimulation by the breast cancer microenvironment, are already showing clinical efficacy. Intervening in the stimulation of tumor cell migration and immune modulation by the microenvironment upcoming fields of great research interest. In contrast, targeting microenvironmental angiogenesis or matrix remodeling appears to be of limited clinical relevance in breast cancer treatment so far. Further research is warranted to optimize intervention strategies and develop predictive tests for the relevance of targeting involved factors within the microenvironment in order to optimally personalize breast cancer treatment.

Development of a radioiodinated apoptosis-inducing ligand, rhTRAIL, and a radiolabelled agonist TRAIL receptor antibody for clinical imaging studies.

BACKGROUND AND PURPOSE: The TNF-related apoptosis inducing ligand (TRAIL) induces apoptosis through activation of the death receptors, TRAIL-R1 and TRAIL-R2. Recombinant human (rh) TRAIL and the TRAIL-R1 directed monoclonal antibody mapatumumab are currently clinically evaluated as anticancer agents. The objective of this study was to develop radiopharmaceuticals targeting the TRAIL-R1, suitable for clinical use to help understand and predict clinical efficacy in patients. EXPERIMENTAL APPROACH: rhTRAIL was radioiodinated with (125) I, and conjugated mapatumumab was radiolabelled with (111) In. The radiopharmaceuticals were characterized, their in vitro stability and death receptor targeting capacities were determined and in vivo biodistribution was studied in nude mice bearing human tumour xenografts with different expression of TRAIL-R1. KEY RESULTS: Labelling efficiencies, radiochemical purity, stability and binding properties were optimized for the radioimmunoconjugates. In vivo biodistribution showed rapid renal clearance of [(125) I]rhTRAIL, with highest kidney activity at 15 min and almost no detectable activity after 4 h. Activity rapidly decreased in almost all organs, except for the xenografts. Radiolabelled mapatumumab showed blood clearance between 24 and 168 h and a reduced decrease in radioactivity in the high receptor expression xenograft. CONCLUSIONS AND IMPLICATIONS: rhTRAIL and mapatumumab can be efficiently radiolabelled. The new radiopharmaceuticals can be used clinically to study pharmacokinetics, biodistribution and tumour targeting, which could support evaluation of the native targeted agents in phase I/II trials.

Intravenous administration of recombinant human IL-10 suppresses the development of anti-thy 1-induced glomerulosclerosis in rats.

AIM: Interleukin-10 (IL-10) is a cytokine with potent antifibrotic and anti-inflammatory properties. However, IL-10 has a very short plasma half-life in vivo. This prompted the question whether a short intravenous treatment might have prolonged effects on more chronic processes like sclerosis. METHODS: Glomerulosclerosis was induced by anti-Thymocyte 1 (Anti-Thy 1) antibody. Four days after induction, an intravenous injection of recombinant human IL-10 (rhIL-10) was given for 3 consecutive days. Untreated rats received vehicle only (phosphate-buffered saline). Parameters of inflammation and fibrosis were assessed at protein and mRNA levels. Untreated rats showed renal histopathological changes as compared to normal rats. RESULTS: Glomerular matrix expansion and inflammatory cell influx was observed and an increase in glomerular-inducible nitric oxide synthetase and α-smooth muscle actin (α-SMA) were found on the protein level, factors that were clearly attenuated by IL-10 treatment. In particular, the decrease of matrix metalloproteinase-13 levels between days 4 and 7 was completely prevented by IL-10. In contrast, IL-10 did not significantly reduce mRNA levels for procollagen α1(1), α-SMA, and transforming growth factor 1. CONCLUSION: A short-term treatment with rhIL-10 after induction of Anti-Thy 1 antibody nephritic rats attenuated intraglomerular inflammation, and at the protein level also influenced the parameters reflecting matrix deposition and degradation. Despite in fact that IL-10 was shown to be effective in the inhibition of matrix deposition, it had no beneficial effect on proteinuria. LAY ABSTRACT: Interleukin-10 is a cytokine with potent antifibrotic and anti-inflammatory properties. Its short plasma half-life raises the question whether a short intravenous treatment might have prolonged effects on chronic disease like sclerosis. To confirm this, recombinant human interleukin-10 was used to treat glomerulosclerosis in rats. The disease was induced by Anti-Thy 1 antibody. Four days after induction, an intravenous injection of IL-10 was given for 3 consecutive days. Untreated rats received vehicle only (phosphate-buffered saline). Parameters of inflammation and fibrosis were assessed at protein and mRNA levels. In this study, untreated rats showed renal histopathological changes as compared to normal rats. Glomerular matrix expansion and inflammatory cell influx was observed, and increases in glomerular nitric oxide synthetase and α-smooth muscle actin α-SMA were found on the protein level. In contrast, treated rats clearly showed reduction of all these parameters. In particular, the decrease of anti-matrix metalloproteinase-13 (MMP-13) levels between days 4 and 7 was completely prevented by IL-10. However, IL-10 did not significantly reduce mRNA levels for procollagen α1(1), α-SMA, and TGFß-1. Based on these results, it can be concluded that a short-term treatment with rhIL-10 after induction of Anti-Thy 1 antibody in nephritic rats attenuated intraglomerular inflammation, and at the protein level also influenced the parameters reflecting matrix deposition and degradation. Despite in fact that IL-10 was shown to be effective in the inhibition of matrix deposition, it had no beneficial effect on proteinuria.

Biodistribution of 89Zr-trastuzumab and PET imaging of HER2-positive lesions in patients with metastatic breast cancer.

We performed a feasibility study to determine the optimal dosage and time of administration of the monoclonal antibody zirconium-89 ((89)Zr)-trastuzumab to enable positron emission tomography (PET) imaging of human epidermal growth factor receptor 2 (HER2)-positive lesions. Fourteen patients with HER2-positive metastatic breast cancer received 37 MBq of (89)Zr-trastuzumab at one of three doses (10 or 50 mg for those who were trastuzumab-naive and 10 mg for those who were already on trastuzumab treatment). The patients underwent at least two PET scans between days 2 and 5. The results of the study showed that the best time for assessment of (89)Zr-trastuzumab uptake by tumors was 4-5 days after the injection. For optimal PET-scan results, trastuzumab-naive patients required a 50 mg dose of (89)Zr-trastuzumab, and patients already on trastuzumab treatment required a 10 mg dose. The accumulation of (89)Zr-trastuzumab in lesions allowed PET imaging of most of the known lesions and some that had been undetected earlier. The relative uptake values (RUVs) (mean +/- SEM) were 12.8 +/- 5.8, 4.1 +/- 1.6, and 3.5 +/- 4.2 in liver, bone, and brain lesions, respectively, and 5.9 +/- 2.4, 2.8 +/- 0.7, 4.0 +/- 0.7, and 0.20 +/- 0.1 in normal liver, spleen, kidneys, and brain tissue, respectively. PET scanning after administration of (89)Zr-trastuzumab at appropriate doses allows visualization and quantification of uptake in HER2-positive lesions in patients with metastatic breast cancer.

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.

111Indium-trastuzumab visualises myocardial human epidermal growth factor receptor 2 expression shortly after anthracycline treatment but not during heart failure: a clue to uncover the mechanisms of trastuzumab-related cardiotoxicity.

AIM: Trastuzumab can induce cardiotoxicity, particularly when combined with anthracyclines. Myocardial human epidermal growth factor receptor 2 (HER2) expression may be transiently upregulated by a compensatory mechanism following cardiac stress. 111In-DTPA-trastuzumab, scintigraphy can detect HER2 positive tumour lesions, however previously, we found myocardial uptake in only 1 of the 15 anthracycline-pre-treated patients with a median of 11 months after the last anthracycline administration. To evaluate whether myocardial HER2 expression is upregulated by anthracycline-induced cardiac stress or in case of heart failure by chronic pressure or volume overload, we performed 111In-DTPA-trastuzumab scans in patients shortly after anthracyclines and with non-anthracycline-related heart failure. METHODS: Patients within 3 weeks after undergoing 4-6 cycles first-line anthracycline-based chemotherapy and patients with heart failure due to cardiac disease underwent gammacamera imaging 48 and 96 h after 111In-DTPA-trastuzumab intravenously. RESULTS: Myocardial 111In-DTPA-trastuzumab uptake was observed in 5 out of 10 anthracycline-treated patients, who all were without symptomatic cardiac dysfunction. None of the 10 heart failure patients showed myocardial uptake. CONCLUSION: Shortly after completion of anthracycline treatment, myocardial HER2 over-expression was detectable in 50% of the patients. 111In-DTPA-trastuzumab scintigraphy after anthracyclines prior to adjuvant trastuzumab potentially identifies patients susceptible for trastuzumab-related cardiotoxicity and thus may facilitate the optimal timing of trastuzumab therapy.

Molecular imaging: what can be used today.

Biochemical cellular targets and more general metabolic processes in cancer cells can be visualised. Extensive data are available on molecular imaging in preclinical models. However, innovative tracers move slowly to the clinic. This review provides information on the currently available methods of metabolic imaging, especially using PET in humans. The uptake mechanisms of tracer methods and a brief discussion of the more 'molecular' targeted methods are presented. The main focus is on the different classes of tracers and their application in various types of cancer within each class of tracers, based on the current literature and our own experience. Studies with [18F]FDG (energy metabolism), radiolabelled amino acids (protein metabolism), [18F]FLT (DNA metabolism), [11C]choline (cell membrane metabolism) as general metabolic tracer methods and [18F]DOPA (biogenic amine metabolism) as a more specific tracer method are discussed. As an example, molecular imaging methods that target the HER2 receptor and somatostatin receptor are described.

Soluble TRAIL concentrations are raised in patients with systemic lupus erythematosus.

BACKGROUND: Increased apoptosis may induce autoimmune conditions. Apoptosis is induced by binding of death receptor ligands, members of the tumour necrosis factor (TNF) superfamily, to their cognate receptors. The Fas-Fas ligand pathway has been studied extensively in relation to systemic lupus erythematosus (SLE). However, other death pathways are also considered important. TNF related apoptosis inducing ligand (TRAIL), another ligand of the TNF superfamily, induces apoptosis in sensitive cells. OBJECTIVE: To assess soluble (s) TRAIL concentrations in sera of SLE patients. METHODS: 40 SLE patients were studied (20 with active and 20 with inactive disease). Serum sTRAIL concentrations were measured by a solid phase sandwich enzyme linked immunosorbent assay. Levels in SLE patients were compared with those in patients with rheumatoid arthritis (n = 20), Wegener's granulomatosis (n = 20), and healthy controls (n = 20). RESULTS: Mean (SEM) serum sTRAIL concentration in SLE patients (936.0 (108.2) pg/ml) was higher than in healthy controls (509.4 (33.8) pg/ml; p<0.01) or in disease control patients with rheumatoid arthritis (443.8 (36.1) pg/ml, p<0.001) or Wegener's granulomatosis (357.1 (32.2) pg/ml; p<0.001). The mean serum sTRAIL concentration was 1010.2 (168.0) pg/ml for patients with inactive disease and 861.8 (138.7) pg/ml for those with active disease. sTRAIL values were not correlated with specific manifestations of the disease, such as leucopenia or lymphopenia, or with SLE disease activity index. CONCLUSIONS: Serum sTRAIL concentrations are increased SLE patients. This seems to be disease specific and could indicate a role for TRAIL in SLE pathophysiology.