Frederike Bensch

HER3, serious partner in crime Therapeutic approaches and potential biomarkers for effect of HER3-targeting

The human epidermal growth factor receptor (HER) family members are targeted by a growing numbers of small molecules and monoclonal antibodies. Resistance against the epidermal growth factor receptor (EGFR) and HER2-targeting agents is a clinically relevant problem forcing research on optimizing targeting of the HER family. In view of its overexpression in tumors, and compensatory role in HER signaling, HER3 has gained much interest as a potential additional target within the HER family. It is the only member of the HER family lacking intrinsic tyrosine kinase activity and therefore its role in cancer has long been underestimated. Drugs that block HER3 or interfere with HER3 dimer signaling, including fully human anti-HER3 antibodies, bispecific antibodies and tyrosine kinase inhibitors (TKIs), are currently becoming available. Several compounds have already entered clinical trial. In the meantime potential biomarkers are tested such as tumor analysis of HER3 expression, functional assays for downstream effector molecules and molecular imaging techniques. This review describes the biology and relevance of HER3 in cancer, agents targeting HER3 and potential biomarkers for effect of HER3-targeting.

Associate editor: B. TeicherHER3, serious partner in crime: Therapeutic approaches and potential biomarkers for effect of HER3-targeting

The human epidermal growth factor receptor (HER) family members are targeted by a growing numbers of small molecules and monoclonal antibodies. Resistance against the epidermal growth factor receptor (EGFR) and HER2-targeting agents is a clinically relevant problem forcing research on optimizing targeting of the HER family. In view of its overexpression in tumors, and compensatory role in HER signaling, HER3 has gained much interest as a potential additional target within the HER family. It is the only member of the HER family lacking intrinsic tyrosine kinase activity and therefore its role in cancer has long been underestimated. Drugs that block HER3 or interfere with HER3 dimer signaling, including fully human anti-HER3 antibodies, bispecific antibodies and tyrosine kinase inhibitors (TKIs), are currently becoming available. Several compounds have already entered clinical trial. In the meantime potential biomarkers are tested such as tumor analysis of HER3 expression, functional assays for downstream effector molecules and molecular imaging techniques. This review describes the biology and relevance of HER3 in cancer, agents targeting HER3 and potential biomarkers for effect of HER3-targeting.

TGF-β antibody uptake in recurrent high grade glioma imaged with 89Zr-fresolimumab PET

Transforming growth factor–β (TGF-β) signaling is involved in glioma development. The monoclonal antibody fresolimumab (GC1008) can neutralize all mammalian isoforms of TGF-β, and tumor uptake can be visualized and quantified with 89Zr-fresolimumab PET in mice. The aim of this study was to investigate the fresolimumab uptake in recurrent high-grade gliomas using 89Zr-fresolimumab PET and to assess treatment outcome in patients with recurrent high-grade glioma treated with fresolimumab. Methods: Patients with recurrent glioma were eligible. After intravenous administration of 37 MBq (5 mg) of 89Zr-fresolimumab, PET scans were acquired on day 2 or day 4 after tracer injection. Thereafter, patients were treated with 5 mg of fresolimumab per kilogram intravenously every 3 wk. 89Zr-fresolimumab tumor uptake was quantified as maximum standardized uptake value (SUVmax). MR imaging for response evaluation was performed after 3 infusions or as clinically indicated. Results: Twelve patients with recurrent high-grade glioma were included: 10 glioblastomas, 1 anaplastic oligodendroglioma, and 1 anaplastic astrocytoma. All patients underwent 89Zr-fresolimumab PET 4 d after injection. In 4 patients, an additional PET scan was obtained on day 2 after injection. SUVmax on day 4 in tumor lesions was 4.6 (range, 1.5–13.9) versus a median SUVmean of 0.3 (range, 0.2–0.5) in normal brain tissue. All patients showed clinical or radiologic progression after 1–3 infusions of fresolimumab. Median progression-free survival was 61 d (range, 25–80 d), and median overall survival was 106 d (range, 37–417 d). Conclusion: 89Zr-fresolimumab penetrated recurrent high-grade gliomas very well but did not result in clinical benefit.

ImmunoPET with Anti-Mesothelin Antibody in Patients with Pancreatic and Ovarian Cancer before Anti-Mesothelin Antibody-Drug Conjugate Treatment

Purpose: Mesothelin (MSLN) is frequently overexpressed in pancreatic and ovarian cancers, making it a potential drug target. We performed an 89Zr-PET imaging study with MMOT0530A, a MSLN antibody, in conjunction with a phase I study with the antibody–drug conjugate DMOT4039A, containing MMOT0530A bound to MMAE. The aim was to study antibody tumor uptake, whole-body distribution, and relation between uptake, response to treatment, and MSLN expression. Experimental Design: Before DMOT4039A treatment, patients received 37 MBq 89Zr-MMOT0530A followed by PET/CT imaging 2, 4, and 7 days postinjection. Tracer uptake was expressed as standardized uptake value (SUV). MSLN expression was determined with immunohistochemistry (IHC) on archival tumor tissue. Results: Eleven patients were included, 7 with pancreatic and 4 with ovarian cancer. IHC MSLN expression varied from absent to strong. Suitable tracer antibody dose was 10 mg MMOT0530A and optimal imaging time was 4 and 7 days postinjection. Tumor tracer uptake occurred in 37 lesions with mean SUVmax of 13.1 (±7.5) on PET 4 days postinjection, with 11.5 (±7.5) in (N = 17) pancreatic and 14.5 (±8.7) in (N = 20) ovarian cancer lesions. Within patients, a mean 2.4-fold (±1.10) difference in uptake between tumor lesions existed. Uptake in blood, liver, kidneys, spleen, and intestine reflected normal antibody distribution. Tracer tumor uptake was correlated to IHC. Best response to DMOT4039A was partial response in one patient. Conclusions: With 89Zr-MMOT0530A-PET, pancreatic and ovarian cancer lesions as well as antibody biodistribution could be visualized. This technique can potentially guide individualized antibody-based treatment. Clin Cancer Res; 22(7); 1642–52. ©2015 AACR.

Molecular imaging for monitoring treatment response in breast cancer patients

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

Zr-89-Lumretuzumab PET Imaging before and during HER3 Antibody Lumretuzumab Treatment in Patients with Solid Tumors

Purpose: We evaluated biodistribution and tumor targeting of 89Zr-lumretuzumab before and during treatment with lumretuzumab, a human epidermal growth factor receptor 3 (HER3)–targeting monoclonal antibody. Experimental Design: Twenty patients with histologically confirmed HER3-expressing tumors received 89Zr-lumretuzumab and underwent positron emission tomography (PET). In part A, 89Zr-lumretuzumab was given with additional, escalating doses of unlabeled lumretuzumab, and scans were performed 2, 4, and 7 days after injection to determine optimal imaging conditions. In part B, patients were scanned following tracer injection before (baseline) and after a pharmacodynamic (PD)-active lumretuzumab dose for saturation analysis. HER3 expression was determined immunohistochemically in skin biopsies. Tracer uptake was calculated as standardized uptake value (SUV). Results: Optimal PET conditions were found to be 4 and 7 days after administration of 89Zr-lumretuzumab with 100-mg unlabeled lumretuzumab. At baseline using 100-mg unlabeled lumretuzumab, the tumor SUVmax was 3.4 (±1.9) at 4 days after injection. SUVmean values for normal blood, liver, lung, and brain tissues were 4.9, 6.4, 0.9 and 0.2, respectively. Saturation analysis (n = 7) showed that 4 days after lumretuzumab administration, tumor uptake decreased by 11.9% (±8.2), 10.0% (±16.5), and 24.6% (±20.9) at PD-active doses of 400, 800, and 1,600 mg, respectively, when compared with baseline. Membranous HER3 was completely downregulated in paired skin biopsies already at and above 400-mg lumretuzumab. Conclusions: PET imaging showed biodistribution and tumor-specific 89Zr-lumretuzumab uptake. Although, PD-active lumretuzumab doses decreased 89Zr-lumretuzumab uptake, there was no clear evidence of tumor saturation by PET imaging as the tumor SUV did not plateau with increasing doses. Clin Cancer Res; 23(20); 6128–37. ©2017 AACR.

A 21-Year-Old Patient With a HER2-Positive Colorectal Cancer

olorectal cancer (CRC) is one of the most common Ccancers diagnosed in men and women worldwide. In the 15to 29-year-old age group CRC accounts for about 2% of all malignancies. Like in adults, presenting symptoms are anemia, abdominal pain, bleeding, weight loss, and change in bowl habits. The clinical presentation and the primary work-up with (total) colonoscopy and a confirmatory biopsy determine further treatment and surveillance strategies. In case of suspected or proven metastatic disease, additional staging by means of laboratory assessments including tumor marker carcinoembryonic antigen (CEA), computed tomography (CT) or magnetic resonance imaging (MRI) and molecular testing (eg, RAS, BRAF) are recommended. Molecular imaging by positron emission tomography (PET) can be of value in case of potentially surgically curable disease, but also in case of a clinical dilemma with unknown/unclear primary origin of tumor and/or metastases and assessment of the receptor status.

Abstract CT017: First-in-human PET imaging with the PD-L1 antibody 89Zr-atezolizumab

Background: Programmed death-ligand 1 (PD-L1) expression has been associated with response to PD-1/PD-L1 inhibition, but responses are also seen in patients with PD-L1 negative tumors when assessed immunohistochemically (IHC) with various antibodies. To help understand these findings, we performed a first-in-human positron emission tomography (PET) imaging study with the anti-PD-L1 antibody atezolizumab labeled with zirconium-89 (89Zr) prior to treatment with atezolizumab to assess normal organ distribution and evaluate tumor tracer uptake in relation to PD-L1 IHC in archival and post-tracer tumor specimen and ultimately to treatment response. Methods: Patients with locally advanced or metastatic non-small cell lung cancer (NSCLC), bladder cancer (BC) or triple-negative breast cancer (TNBC) received 10 mg unlabeled atezolizumab plus 37 MBq 89Zr-atezolizumab (~1 mg) followed by up to 4 PET scans (1 hour, days 2, 4 and 7 post-injection (pi)). Next, after obtaining a tumor biopsy for PD-L1 IHC 8-10 days after tracer injection, patients received atezolizumab (1200 mg) i.v. once every 3 weeks until disease progression (NCT02453984 and NCT02478099). Response was assessed every 6 weeks with RECIST1.1. Normal organ tracer uptake was calculated as percentage of the injected dose/kg (%ID/kg) 4 and 7 days pi, tumor tracer uptake as maximum standardized uptake value (SUVmax) and %ID/kg 7 days pi. Tumor biopsy PD-L1 expression was assessed in tumor cells (TC) and tumor infiltrating immune cells (IC) by HistoGeneX IHC with the SP142 assay (Ventana). Results: In this ongoing trial, 16/25 patients completed the PET series and received atezolizumab at least until the first response assessment. The median follow-up of these patients is 16 weeks (6-40+, NSCLC=6, BC=8, TNBC=2). The highest normal organ 89Zr-atezolizumab uptake was seen in the spleen (16.3±3.6 %ID/kg 4 days and 17.9±3.6 %ID/kg 7 days pi), and uptake in other lymphatic organs (single normal lymph nodes and tonsil) and sites of (chronic) inflammation (e.g. chronic sinusitis and bursitis) were detected. Uptake in liver, kidney and intestine was similar to other antibodies with 7.3±1.6, 5.5±2.0 and 4.7±2.4 %ID/kg, respectively, 7 days pi. Tumor SUVmax ranged between 1.6 and 46.0 (1.8-12.4 %ID/kg), with an up to 9-fold difference within patients, and 4-fold difference between patients. In 4 biopsied lesions with IC/TC 0, 89Zr-atezolizumab uptake calculated as SUVmax was 10.0±3.6 (7.1±1.6 %ID/kg). At this time only 4 biopsies had a IHC score of 2+ on either IC or TC, and there were no biopsies with a score of 3+, limiting the ability to determine correlation of PD-L1 IHC to imaging data. Conclusion: 89Zr-atezolizumab imaging showed high uptake in normal spleen, other normal lymphoid organs and regions of inflammation. Uptake in tumor lesions was heterogeneous within and between patients and even PD-L1 IHC 0 tumors showed clear tracer uptake. Citation Format: Frederike Bensch, Elly van der Veen, Annelies Jorritsma, Marjolijn Lub-de Hooge, Ronald Boellaard, Sjoukje Oosting, Carolien Schroder, Jeroen Hiltermann, Anthonie van der Wekken, Harry Groen, Bernard Fine, Nathan McKnight, Sandra Sanabria Bohorquez, Simon Williams, Luisa Veronese, Christoph Mancao, Adrienne H. Brouwers, Elisabeth de Vries. First-in-human PET imaging with the PD-L1 antibody 89Zr-atezolizumab [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr CT017. doi:10.1158/1538-7445.AM2017-CT017

Abstract OT3-2-01: IMPACT: IMaging PAtients for Cancer drug selecTion – Metastatic breast cancer (MBC)

Background: Therapy of newly identified MBC is largely based on estrogen receptor (ER) and human epidermal growth factor receptor 2 (HER2) status. Optimal receptor information should be up-to-date and preferably from the whole body, given receptor conversion over time and intra-patient tumor heterogeneity. Novel molecular imaging by means of 18F-fluoroestradiol (FES)- and 89Zr-trastuzumab-PET/CT is a non-invasive, patient friendly way to obtain such information. Comprehensive prospective data comparing novel molecular imaging, metastasis biopsy and blood biomarkers, are needed to assess clinical utility for optimal therapy guidance and response prediction. Trial design: The IMPACT-MBC trial (NCT01957332), is a multicenter prospective cohort study, supported by the Dutch Cancer Society-Alpe d’HuZes, in which n=200 newly diagnosed MBC patients will be entered. Prior to start of treatment patients will undergo i) standard MBC work up including bone scan, diagnostic CT and 18F-fluorodeoxyglucose(FDG)-PET/CT, ii) a metastasis biopsy, for standard (immuno)pathology and DNA sequencing, iii) 18F-FES- and 89Zr-trastuzumab-PET/CT to assess whole-body metastatic ER and HER2 status, and iv) blood sampling (CTCs, ctDNA, germline DNA, 89Zr-radioactivity measurements). Treatment advice will be based on standard work up and experimental PET scans. Tumor response is assessed by a 2 week 18F-FDG-PET/CT (experimental) and an 8 week diagnostic CT (standard; primary outcome). Eligibility criteria: All newly diagnosed non-rapidly progressive MBC patients with measurable or clinical evaluable (bone only) disease can be enrolled, regardless of primary tumor ER and HER2 status. Patients should be eligible for systemic therapy, but not require immediate start of chemotherapy. A histological biopsy of a metastatic lesion should be safely obtainable. Excluded are pregnant or lactating women and patients with a prior allergic reaction to immunoglobulins. Specific aims: i) To assess the (added) clinical utility of 18F-FES- and 89Zr-trastuzumab-PET/CT, in the setting of MBC at first presentation, in relation to other diagnostics, ii) to assess the relation of experimental 18F-FES-, 89Zr-trastuzumab- and 2 week 18F-FDG-PET/CT with (progression free) survival and iii) to assess the cost-effectiveness of the experimental PET/CT scans. Statistical methods: IMPACT-MBC aims to model the predictive value of several tests (novel molecular imaging, biopsy and blood biomarkers) in combination, by means of multivariable regression-model based techniques, combined with state-of-the-art methods for estimating the added value of novel tests to existing information (e.g. NRI, IDI). All these analyses will be employed both on (predicting responsiveness on) a patient- and metastasis level. Present accrual and target accrual: The IMPACT-MBC trial was opened for accrual at the University Medical Center (UMC) Groningen, in August 2013. Accrual rate is as anticipated 2-3 patients/month/center. The two other participating centers, Radboud MC Nijmegen and VUmc Amsterdam recently opened. It is anticipated that accrual of patients will be finalized in 2016. Citation Format: Frederike Bensch, Adrienne Brouwers, Andor Glaudemans, Johan de Jong, Erik de Vries, Winette van de Graaf, Eline Boon, Wim Oyen, Lioe-Fee de Geus-Oei, Eric Visser, Erik van Helden, Willemien Menke-van der Hoeven van Oordt, Henk Verheul, Otto Hoekstra, Jim Janssen, Marc Huisman, Sjoerd Elias, Carl Moons, Liesbeth de Vries, Carolien Schroder. IMPACT: IMaging PAtients for Cancer drug selecTion – Metastatic breast cancer (MBC) [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr OT3-2-01.

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.