Thorsten Persigehl

Epidermal Growth Factor Receptor Mutation in Lung Adenocarcinomas: Relationship with CT Characteristics and Histologic Subtypes

PURPOSE To retrospectively identify quantitative computed tomographic (CT) features that correlate with epidermal growth factor receptor (EGFR) mutation in surgically resected lung adenocarcinomas stratified by the International Association for the Study of Lung Cancer (IASLC), American Thoracic Society (ATS), and European Respiratory Society (ERS) classification in an East Asian cohort of patients known to have a high prevalence of EGFR mutations. MATERIALS AND METHODS An institutional review board approved this study and waived informed consent. In 153 surgically resected lung adenocarcinomas, EGFR mutation was determined by direct DNA sequencing. Histologic subtype was classified according to IASLC/ATS/ERS classification of lung adenocarcinoma. At preoperative chest CT, the percentage of ground-glass opacity (GGO) volume and total tumor volume of each tumor were measured by using a semiautomated algorithm. Distribution of EGFR mutation according to histologic subtype, percentage of GGO volume, and total tumor volume was evaluated by using the Fisher exact test, the Student t test, trend analysis, and multiple logistic regression analysis. RESULTS Exon 21 missense mutation was more frequent in lepidic predominant adenocarcinomas than in other histologic subtypes (odds ratio, 3.44; 95% confidence interval: 1.53, 7.74; P = .003). GGO volume percentage in tumors with exon 21 missense mutation (61.7% ± 31.9 [standard deviation]) was significantly higher than that in EGFR wild-type tumors (30.0% ± 38.5) (P = .0001) and exon 19-mutated tumors (28.9% ± 37.7) (P = .0006). A significant trend of prevalence of exon 21 missense mutation increasing along with increasing GGO volume (P = .0008) was found. CONCLUSION GGO volume percentage in tumors with exon 21 missense mutation was significantly higher than that in tumors with other EGFR mutation status. This can be related to the fact that exon 21 missense mutation was significantly more frequent in lepidic predominant adenocarcinomas, including adenocarcinoma in situ, minimally invasive adenocarcinoma, and lepidic predominant invasive adenocarcinoma, according to IASLE/ATS/ERS classification.

Infarction of tumor vessels by NGR-peptide-directed targeting of tissue factor: experimental results and first-in-man experience.

We induced thrombosis of blood vessels in solid tumors in mice by a fusion protein consisting of the extracellular domain of tissue factor (truncated tissue factor, tTF) and the peptide GNGRAHA, targeting aminopeptidase N (CD13) and the integrin alpha(v)beta(3) (CD51/CD61) on tumor vascular endothelium. The designed fusion protein tTF-NGR retained its thrombogenic activity as demonstrated by coagulation assays. In vivo studies in mice bearing established human adenocarcinoma (A549), melanoma (M21), and fibrosarcoma (HT1080) revealed that systemic administration of tTF-NGR induced partial or complete thrombotic occlusion of tumor vessels as shown by histologic analysis. tTF-NGR, but not untargeted tTF, induced significant tumor growth retardation or regression in all 3 types of solid tumors. Thrombosis induction in tumor vessels by tTF-NGR was also shown by contrast enhanced magnetic resonance imaging (MRI). In the human fibrosarcoma xenograft model, MRI revealed a significant reduction of tumor perfusion by administration of tTF-NGR. Clinical first-in-man application of low dosages of this targeted coagulation factor revealed good tolerability and decreased tumor perfusion as measured by MRI. Targeted thrombosis in the tumor vasculature induced by tTF-NGR may be a promising strategy for the treatment of cancer.

Heterogeneous Mechanisms of Primary and Acquired Resistance to Third-Generation EGFR Inhibitors.

Purpose: To identify novel mechanisms of resistance to third-generation EGFR inhibitors in patients with lung adenocarcinoma that progressed under therapy with either AZD9291 or rociletinib (CO-1686). Experimental Design: We analyzed tumor biopsies from seven patients obtained before, during, and/or after treatment with AZD9291 or rociletinib (CO-1686). Targeted sequencing and FISH analyses were performed, and the relevance of candidate genes was functionally assessed in in vitro models. Results: We found recurrent amplification of either MET or ERBB2 in tumors that were resistant or developed resistance to third-generation EGFR inhibitors and show that ERBB2 and MET activation can confer resistance to these compounds. Furthermore, we identified a KRASG12S mutation in a patient with acquired resistance to AZD9291 as a potential driver of acquired resistance. Finally, we show that dual inhibition of EGFR/MEK might be a viable strategy to overcome resistance in EGFR-mutant cells expressing mutant KRAS. Conclusions: Our data suggest that heterogeneous mechanisms of resistance can drive primary and acquired resistance to third-generation EGFR inhibitors and provide a rationale for potential combination strategies. Clin Cancer Res; 22(19); 4837–47. ©2016 AACR.

Inhibition of tumor growth by RGD peptide-directed delivery of truncated tissue factor to the tumor vasculature.

Selective activation of blood coagulation in tumor vessels with subsequent tumor infarction is a promising anticancer strategy. To this end, a fusion protein consisting of the extracellular domain of tissue factor [truncated tissue factor (tTF)] was fused to the peptide GRGDSP selectively targeting αv-integrins on tumor endothelial cells. tTF-RGD retained its thrombogenic and integrin-binding activity in vitro. In vivo studies in mice bearing human adenocarcinomas (CCL185), melanoma (M21), and fibrosarcoma (HT1080) revealed that i.v. administration of tTF-RGD induced thrombotic occlusion of tumor vessels resulting in tumor growth retardation or regression in all three types of solid tumors. No apparent side effects, such as thrombosis, in other organs or other treatment-related toxicities were observed. Reduced tumor blood flow in tTF-RGD–treated animals as determined by contrast-enhanced magnetic resonance imaging underlines the proposed mechanism. In conclusion, we consider RGD peptide–directed delivery of tTF as alternative to previously used antibody fusion proteins. Small peptide-directed delivery of coaguligands does not cause immunologic side effects and those caused by accumulation in the reticuloendothelial system. This is the first report to describe the induction of selective thrombosis in tumor vessels by RGD peptide–directed delivery of tTF, which may be a promising strategy for the treatment of cancer.

A Synergistic Interaction between Chk1- and MK2 Inhibitors in KRAS-Mutant Cancer

KRAS is one of the most frequently mutated oncogenes in human cancer. Despite substantial efforts, no clinically applicable strategy has yet been developed to effectively treat KRAS-mutant tumors. Here, we perform a cell-line-based screen and identify strong synergistic interactions between cell-cycle checkpoint-abrogating Chk1- and MK2 inhibitors, specifically in KRAS- and BRAF-driven cells. Mechanistically, we show that KRAS-mutant cancer displays intrinsic genotoxic stress, leading to tonic Chk1- and MK2 activity. We demonstrate that simultaneous Chk1- and MK2 inhibition leads to mitotic catastrophe in KRAS-mutant cells. This actionable synergistic interaction is validated using xenograft models, as well as distinct Kras- or Braf-driven autochthonous murine cancer models. Lastly, we show that combined checkpoint inhibition induces apoptotic cell death in KRAS- or BRAF-mutant tumor cells directly isolated from patients. These results strongly recommend simultaneous Chk1- and MK2 inhibition as a therapeutic strategy for the treatment of KRAS- or BRAF-driven cancers.

Assessment of Tumor Size Reduction Improves Outcome Prediction of Positron Emission Tomography/Computed Tomography After Chemotherapy in Advanced-Stage Hodgkin Lymphoma

PURPOSE Positron emission tomography (PET) after chemotherapy can guide consolidating radiotherapy in advanced-stage Hodgkin lymphoma (HL). This analysis aims to improve outcome prediction by integrating additional criteria derived by computed tomography (CT). PATIENTS AND METHODS The analysis set consisted of 739 patients with residues≥2.5 cm after chemotherapy from a total of 2,126 patients treated in the HD15 trial (HD15 for advanced stage Hodgkins disease: Quality assurance protocol for reduction of toxicity and the prognostic relevance of fluorodeoxyglucose-positron-emission tomography [FDG-PET] in the first-line treatment of advanced-stage Hodgkins disease) performed by the German Hodgkin Study Group. A central panel performed image analysis and interpretation of CT scans before and after chemotherapy as well as PET scans after chemotherapy. Prognosis was evaluated by using progression-free survival (PFS); groups were compared with the log-rank test. Potential prognostic factors were investigated by using receiver operating characteristic analysis and logistic regression. RESULTS In all, 548 (74%) of 739 patients had PET-negative residues after chemotherapy; these patients did not receive additional radiotherapy and showed a 4-year PFS of 91.5%. The 191 PET-positive patients (26%) receiving additional radiotherapy had a 4-year PFS of 86.1% (P=.022). CT alone did not allow further separation of patients in partial remission by risk of recurrence (P=.9). In the subgroup of the 54 PET-positive patients with a relative reduction of less than 40%, the risk of progression or relapse within the first year was 23.1% compared with 5.3% for patients with a larger reduction (difference, 17.9%; 95% CI, 5.8% to 30%). CONCLUSION Patients with HL who have PET-positive residual disease after chemotherapy and poor tumor shrinkage are at high risk of progression or relapse.

Prediction of antiangiogenic treatment efficacy by iron oxide enhanced parametric magnetic resonance imaging

Rationale and Objectives:Tools for monitoring modern target-specific antiangiogenic and antivascular therapies are highly desirable because treatment strategies are time consuming, expensive, and yet sometimes ineffective. Therefore, the aim of this experimental study was to evaluate the predictive value of steady-state ultrasmall particles of iron oxide (USPIO; SH U 555 C)-enhanced magnetic resonance imaging (MRI) for early assessment of antivascular tumor-treatment effectiveness. Methods:Mice were inoculated with an HT-1080 fibrosarcoma xenograft and subjected to target-specific antivascular therapy using a selective thrombogenic vascular-targeting agent (truncated tissue factor fused to RGD peptide) or saline as control. Four to 8 hours after treatment, the USPIO-induced change in the transverse relaxation rate &Dgr;R2* was measured by MRI, and the vascular volume fraction (VVF) was calculated by calibrating &Dgr;R2* of the tumor by &Dgr;R2* of muscle tissue. Treatment response was defined by histologic grading of vascular thrombosis and tumor necrosis. Results:After thrombogenic treatment, half of the HT-1080 xenograft-bearing animals showed only minor (=nonresponder) whereas the other half showed extensive tumor thrombosis (=responders). For responders, a significant decrease of &Dgr;R2* and VVF was observed compared with the control group (&Dgr;R2*: controls: 16 ± 1 s−1 vs. responder: 4 ± 2 s−1; P < 0.001) whereas &Dgr;R2* and VVF remained nearly unchanged for nonresponders (&Dgr;R2*: nonresponder 14 ± 2 s−1). VVF and &Dgr;R2* values correlated inversely with the histologic grading of vascular thrombosis and tumor necrosis (VVF: r = −0.8; &Dgr;R2*: r = −0.71; P < 0.01). Conclusion:USPIO-enhanced MRI allows a noninvasive, early assessment of treatment efficacy of thrombogenic vascular-targeting agents.

Near-infrared imaging of the breast using omocianine as a fluorescent dye: results of a placebo-controlled, clinical, multicenter trial.

Objectives:To evaluate the efficacy of the near-infrared (NIR) dye Omocianine in a placebo-controlled, dose-escalating multicenter trial for the detection of malignant breast lesions by using a NIR imaging system. Materials and Methods:The study was approved by the ethical review board of Berlin and Münster,, and all participants provided written informed consent. Fifty-two consecutive patients were examined with NIR imaging before, during, and after intravenous injection of Omocianine. Three-dimensional absorption and fluorescence diffuse optical tomography scans were recorded simultaneously on a prototype NIR imaging unit (Computed Tomography Laser Mammography, Imaging Diagnostic Systems, Inc., Ft. Lauderdale, FL). Two readers assessed the images in consensus and assigned visibility scores to lesions seen on the absorption and absorption-corrected fluorescence diffuse optical tomography mammograms. Imaging results were compared with histopathologic findings. To analyze whether lesion detection rate for malignant lesions depended on the size of the lesion, lesions were dichotomized into those measuring less than 20 mm and those measuring 20 mm or more. Moreover, the shortest diameter between the center of the target lesions and the skin was measured on axial optical mammography data. Results:There were a total of 53 target lesions. Histopathologically, 22 target lesions were diagnosed as benign and 31 target lesions as malignant. In the absorption mode, a detection rate of 11.8% for benign and 44.4% for malignant lesions across all dose groups was found. In the fluorescence mode, a detection rate of 17.6% was revealed for benign and 55.6% for malignant lesions across all dose groups. For dose group 0.1 mg/kg, a detection rate of 100% was found for malignant lesions in the fluorescence mode and 71.4% in the absorption mode. Across all dose groups in the fluorescence mode, detection rate for malignant target lesions in breasts smaller than the median axial breast diameter of 12.8 cm was higher with 69.2% than in median diameters ≥12.8 cm with 46.2%. Omocianine-enhanced fluorescence optical mammography allowed a better detection of more superficially located lesions, with detection rates for a lesion-skin distance <20 mm of 63.6%, for <30 mm of 47.4% and for ≥30 mm of 25%. Malignant target lesions with a diameter ≥20 mm were slightly better detected with 61.5% in contrast to suspicious lesions <20 mm with 53.8%. Optimal imaging time points varied strongly among the different target lesions and Omocianine dose groups, with a mean optimal time point for malignant lesions at 188 ± 385 minutes. Conclusion:Preliminary data suggest that fluorescence imaging after Omocianine administration has the potential to detect malignant breast lesions. As our study showed considerable variations in the detection of breast cancer at different fluorophore concentrations ranging from 20% to 100%, future work needs to be done to assess the suitable dose for NIR imaging.

Optical techniques for the molecular imaging of angiogenesis

The process of angiogenesis, an essential hallmark for tumour development as well as for several inflammatory diseases and physiological phenomena, is of growing interest for diagnosis and therapy in oncology. In the context of biochemical characterisation of key molecules involved in angiogenesis, several targets for imaging and therapy could be identified in the last decade. Optical imaging (OI) relies on the visualisation of near infrared (NIR) light, either its absorption and scattering in tissue (non-enhanced OI) or using fluorescent contrast agents. OI offers excellent signal to noise ratios due to virtually absent background fluorescence in the NIR range and is thus a versatile tool to image specific molecular target structures in vivo. This work intends to provide a survey of the different approaches to imaging of angiogenesis using OI methods in preclinical research as well as first clinical trials. Different imaging modalities as well as various optical contrast agents are briefly discussed.

Tumor Blood Volume Determination by Using Susceptibility-corrected ΔR2* Multiecho MR

PURPOSE To evaluate a susceptibility-corrected multiecho magnetic resonance (MR) relaxometry technique for an accurate and robust determination of DeltaR2* as a noninvasive surrogate parameter of the perfused tumor blood volume. MATERIALS AND METHODS All experiments were approved by the institutional animal care committee. In a glass tube phantom with different superparamagnetic iron oxide (SPIO) particle concentrations and at tumor mice xenografts with DU-4475, HT-1080, and MDA-MB-435 tumors (n = 15 total, n = 5 per model) with different degrees of neovascularization after injection of different ultrasmall SPIO (USPIO) doses changes of the transverse relaxation rate (DeltaR2*) were determined by using a fixed echo time (TE) of 22 msec and a susceptibility-corrected multigradient-echo technique. The mean DeltaR2* value and the vascular volume fraction (VVF) of each tumor was determined and compared with independent in vivo fluorescent tumor perfusion measurements and histologic analysis helped determine microvessel density (MVD). Statistical differences were tested by using analysis of variance and linear correlations. RESULTS For the phantom study, DeltaR2* maps calculated with a fixed TE of 22 msec showed a higher standard deviation of the noise index compared with the susceptibility-corrected multiecho technique. For the xenograft model, mean tumor DeltaR2* values (+/- standard error of the mean) showed significant differences between the various tumors (eg, DU-4475: 12.3 sec(-1) +/- 2.67, HT-1080: 36.47 sec(-1) +/- 5.84, and MDA-MB-435: 64.01 sec(-1) +/- 8.87 at 80 mumol of iron per kilogram; P < .05). DeltaR2* values increased dose dependently and in a linear fashion, resulting in reproducibly stable VVF measurements. Fluorescent tumor perfusion measurements and MVD counts corroborated the MR results. CONCLUSION Susceptibility-corrected multiecho MR relaxometry allows a highly accurate and robust determination of DeltaR2* and VVF with an excellent dynamic range for tumor characterization at clinically relevant doses of USPIO.