Andreas Wicki

The potential role of podoplanin in tumour invasion.

Podoplanin is a small mucin-like transmembrane protein, widely expressed in various specialised cell types throughout the body. Here, we revisit the mechanism of podoplanin-mediated tumour invasion. We compare molecular pathways leading to single and collective cell invasion and discuss novel distinct concepts of tumour cell invasion.

NCAM‐induced focal adhesion assembly: a functional switch upon loss of E‐cadherin

Loss of expression of the cell–cell adhesion molecule E‐cadherin is a hallmark of epithelial–mesenchymal transition (EMT) in development and in the progression from epithelial tumours to invasive and metastatic cancers. Here, we demonstrate that the loss of E‐cadherin function upregulates expression of the neuronal cell adhesion molecule (NCAM). Subsequently, a subset of NCAM translocates from fibroblast growth factor receptor (FGFR) complexes outside lipid rafts into lipid rafts where it stimulates the non‐receptor tyrosine kinase p59Fyn leading to the phosphorylation and activation of focal adhesion kinase and the assembly of integrin‐mediated focal adhesions. Ablation of NCAM expression during EMT inhibits focal adhesion assembly, cell spreading and EMT. Conversely, forced expression of NCAM induces epithelial cell delamination and migration, and high NCAM expression correlates with tumour invasion. These results establish a mechanistic link between the loss of E‐cadherin expression, NCAM function, focal adhesion assembly and cell migration and invasion.

Exendin-4–Based Radiopharmaceuticals for Glucagonlike Peptide-1 Receptor PET/CT and SPECT/CT

Strong overexpression of glucagonlike peptide-1 (GLP-1) receptors in human insulinoma provides an attractive target for imaging. The first clinical trials demonstrated that GLP-1 receptor SPECT/CT using [Lys40(Ahx [6-aminohexanoic acid]-DOTA-111In)NH2]-exendin-4 can localize hardly detectable insulinomas. However, [Lys40(Ahx-DOTA-111In)NH2]-exendin-4 imaging has drawbacks related to the use of 111In in that it is costly and carries a relatively high radiation burden for the patient. The aim of this study was the preclinical evaluation of [Lys40(Ahx-DOTA-68Ga)NH2]-exendin-4 for PET/CT and [Lys40(Ahx-hydrazinonicotinamide [HYNIC]-99mTc)NH2]-exendin-4 for SPECT/CT. Methods: Internalization, biodistribution, dosimetry, and imaging studies were performed in the Rip1Tag2 mouse model of pancreatic β-cell carcinogenesis and compared with our gold standard [Lys40(Ahx-DOTA-111In)NH2]-exendin-4. Poly-glutamic acid and Gelofusine, a gelatin-based plasma expander, were used for renal uptake reduction studies. Results: The tumor uptake of [Lys40(Ahx-DOTA-68Ga)NH2]-exendin-4 was 205 ± 59 percentage injected activity per gram of tissue at 4 h. Other GLP-1 receptor–positive organs showed more than 4.8 times lower radioactivity uptake. [Lys40(Ahx-HYNIC-99mTc/ethylenediaminediacetic acid [EDDA])NH2]-exendin-4, compared with its 111In- and 68Ga-labeled sister compounds, showed significantly less tumor and organ uptake. The significantly lower tumor and organ uptake of [Lys40(Ahx-HYNIC-99mTc/EDDA)NH2]-exendin-4 did not result in inferior tumor-to-organ ratios or reduced image quality. All radiopeptides tested showed a high tumor-to-background ratio, resulting in the visualization of small tumors (maximum diameter between 1.0 and 3.2 mm) by SPECT and PET. The only exception was the kidneys, which also showed high uptake. This uptake could be reduced by 49%−78% using poly-glutamic acid, Gelofusine, or a combination of the 2. The estimated effective radiation dose was 3.7 μSv/MBq for [Lys40(Ahx-HYNIC-99mTc/EDDA)NH2]-exendin-4, which was 8 times less than that for [Lys40(Ahx-DOTA-68Ga)NH2]-exendin-4 and 43 times less than that for [Lys40(Ahx-DOTA-111In)NH2]-exendin-4. Conclusion: These promising pharmacokinetic and imaging data show that [Lys40(Ahx-DOTA-68Ga)NH2]-exendin-4 and [Lys40(Ahx-HYNIC-99mTc/EDDA)NH2]-exendin-4 are suitable candidates for clinical GLP-1 receptor imaging studies.

[Lys40(Ahx-DTPA-111In)NH2]-Exendin-4 is a highly efficient radiotherapeutic for glucagon-like peptide-1 receptor-targeted therapy for insulinoma.

Purpose: Although metabolic changes make diagnosis of insulinoma relatively easy, surgical removal is hampered by difficulties in locating it, and there is no efficient treatment for malignant insulinoma. We have previously shown that the high density of glucagon-like peptide-1 receptors (GLP-1R) in human insulinoma cells provides an attractive target for molecular imaging and internal radiotherapy. In this study, we investigated the therapeutic potential of [Lys40(Ahx-DTPA-111In)NH2]-Exendin-4, an 111In-labeled agonist of GLP-1, in a transgenic mouse model of human insulinoma. Experimental Design: [Lys40(Ahx-DTPA-111In)NH2]-Exendin-4 was assessed in the Rip1Tag2 mouse model of pancreatic β-cell carcinogenesis, which exhibits a GLP-1R expression comparable with human insulinoma. Mice were injected with 1.1, 5.6, or 28 MBq of the radiopeptide and sacrificed 7 days after injection. Tumor uptake and response, the mechanism of action of the radiopeptide, and therapy toxicity were investigated. Results: Tumor uptake was >200% injected activity per gram, with a dose deposition of 3 Gy/MBq at 40 pmol [Lys40(Ahx-DTPA-111In)NH2]-Exendin-4. Other GLP-1R–positive organs showed ≥30 times lower dose deposition. A single injection of [Lys40(Ahx-DTPA-111In)NH2]-Exendin-4 resulted in a reduction of the tumor volume by up to 94% in a dose-dependent manner without significant acute organ toxicity. The therapeutic effect was due to increased tumor cell apoptosis and necrosis and decreased proliferation. Conclusions: The results suggest that [Lys40(Ahx-DTPA-111In)NH2]-Exendin-4 is a promising radiopeptide capable of selectively targeting insulinoma. Furthermore, Auger-emitting radiopharmaceuticals such as 111In are able to produce a marked therapeutic effect if a high tumor uptake is achieved.

Targeting Tumor-Associated Endothelial Cells: Anti-VEGFR2 Immunoliposomes Mediate Tumor Vessel Disruption and Inhibit Tumor Growth

Purpose: Angiogenesis is a key process in tumor progression. By binding VEGF, VEGF receptor-2 (VEGFR2) is a main signaling transducer in tumor-associated angiogenesis. Accordingly, therapeutic approaches against the VEGF/VEGFR2 signaling axis have been designed. However, an efficient and specific chemotherapeutic targeting of tumor-associated endothelial cells has not yet been achieved. Experimental Design: We have employed anti-VEGFR2 antibodies covalently linked to pegylated liposomal doxorubicin (PLD) to specifically ablate tumor-associated endothelial cells in the Rip1Tag2 mouse model of insulinoma, in the MMTV-PyMT mouse model of breast cancer, and in the HT-29 human colon cancer xenograft transplantation model. Results: In each model, anti-VEGFR2–targeted immunoliposomes (ILs) loaded with doxorubicin (anti-VEGFR2-ILs-dox) were superior in therapeutic efficacy to empty liposomes, empty anti-VEGFR2-ILs, antibodies alone, and PLD. Efficacy was similar to that of the oral VEGFR1, -2, and -3 inhibitor PTK787. Detailed histopathologic and molecular analysis revealed a strong antiangiogenic effect of anti-VEGFR2-ILs-dox, and the observed antiangiogenic therapy was significantly more efficient in reducing tumor burden in well-vascularized transgenic mouse models as compared with the less-vascularized xenograft model. Conclusions: Anti-VEGFR2 ILs provide a highly efficient approach to selectively deplete VEGFR2-expressing tumor vasculature. They offer a novel and promising anticancer strategy. Clin Cancer Res; 18(2); 454–64. ©2011 AACR.

Systemic inflammation in a melanoma patient treated with immune checkpoint inhibitors—an autopsy study

BackgroundImmune checkpoint inhibitors targeting cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) and programmed cell death protein 1 (PD-1) have been recently approved for treatment of patients with metastatic melanoma and non-small cell lung cancer (NSCLC). Despite important clinical benefits, these therapies are associated with a diverse spectrum of immune-related adverse events (irAEs) that are typically transient, but occasionally severe or even fatal.Case presentationThis autopsy case illustrates that clinically overt irAEs may represent only a fraction of the total spectrum of immune-related organ pathology in patients treated with immune checkpoint inhibitors. We report a comprehensive analysis of systemic irAE pathology based on the autopsy of a 35-year-old female patient with metastatic melanoma treated first with ipilimumab and then nivolumab. The clinical course was characterized by a mixed tumor response with regression of skin and lung metastases and fatal progression of metastatic disease in the small bowel, peritoneum and brain. During therapy with ipilimumab, radiographic features of immune-related pneumonitis were noted. The autopsy examination established a sarcoid-like granulomatous reaction of the lung, pulmonary fibrosis and diffuse alveolar damage. Importantly, a clinically unapparent but histologically striking systemic inflammation involving the heart, central nervous system, liver and bone marrow was identified. Severe immune-related end-organ damage due to lymphocytic myocarditis was found.ConclusionsAutopsy studies are an important measure of quality control and may identify clinically unapparent irAEs in patients treated with immunotherapy. Pathologists and clinicians need to be aware of the broad spectrum of irAEs for timely management of treatment-related morbidity.

Acquired Resistance to Clinical Cancer Therapy: A Twist in Physiological Signaling

Although modern therapeutic strategies have brought significant progress to cancer care in the last 30 years, drug resistance to targeted monotherapies has emerged as a major challenge. Aberrant regulation of multiple physiological signaling pathways indispensable for developmental and metabolic homeostasis, such as hyperactivation of pro-survival signaling axes, loss of suppressive regulations, and impaired functionalities of the immune system, have been extensively investigated aiming to understand the diversity of molecular mechanisms that underlie cancer development and progression. In this review, we intend to discuss the molecular mechanisms of how conventional physiological signal transduction confers to acquired drug resistance in cancer patients. We will particularly focus on protooncogenic receptor kinase inhibition-elicited tumor cell adaptation through two major core downstream signaling cascades, the PI3K/Akt and MAPK pathways. These pathways are crucial for cell growth and differentiation and are frequently hyperactivated during tumorigenesis. In addition, we also emphasize the emerging roles of the deregulated host immune system that may actively promote cancer progression and attenuate immunosurveillance in cancer therapies. Understanding these mechanisms may help to develop more effective therapeutic strategies that are able to keep the tumor in check and even possibly turn cancer into a chronic disease.

Diet and cancer

Large claims have been made for the effectiveness of particular diets in preventing cancer or inhibiting its progression. However, more recent clinical studies have not confirmed this. Instead it seems that rather than specific dietary constituents, total calories influence cancer incidence and progression. In this review article, we summarise and interpret the available evidence for links between diet and cancer.

Kras in metastatic colorectal cancer

Kras, a small intracellular GTPase, is a central intermediary of the epidermal growth factor receptor (EGFR) and other tyrosine kinase receptor pathways. Increased EGFR and Kras signalling is involved in colorectal carcinogenesis and tumour progression. Mutations of Kras result in the loss of its GTPase activity and thus in a constitutive activation of Kras signalling. Kras mutations are found in 30-60% of colorectal cancers. The concordance between Kras mutations in the primary tumour and related metastatic sites is high. Since mutation of Kras confers resistance to anti-EGFR-antibody therapy, it is critical to assess Kras mutational status in colorectal cancer patients. Anti-EGFR-antibody therapy improves survival in patients with metastatic colorectal cancer and wild-type Kras.

Large-scale manufacturing of GMP-compliant anti-EGFR targeted nanocarriers: Production of doxorubicin-loaded anti-EGFR-immunoliposomes for a first-in-man clinical trial

We describe the large-scale, GMP-compliant production process of doxorubicin-loaded and anti-EGFR-coated immunoliposomes (anti-EGFR-ILs-dox) used in a first-in-man, dose escalation clinical trial. 10 batches of this nanoparticle have been produced in clean room facilities. Stability data from the pre-GMP and the GMP batch indicate that the anti-EGFR-ILs-dox nanoparticle was stable for at least 18 months after release. Release criteria included visual inspection, sterility testing, as well as measurements of pH (pH 5.0-7.0), doxorubicin HCl concentration (0.45-0.55 mg/ml), endotoxin concentration (<1.21 IU/ml), leakage (<10%), particle size (Z-average of Caelyx ± 20 nm), and particle uptake (uptake absolute: >0.50 ng doxorubicin/μg protein; uptake relatively to PLD: >5 fold). All batches fulfilled the defined release criteria, indicating a high reproducibility as well as batch-to-batch uniformity of the main physico-chemical features of the nanoparticles in the setting of the large-scale GMP process. In the clinical trial, 29 patients were treated with this nanoparticle between 2007 and 2010. Pharmacokinetic data of anti-EGFR-ILs-dox collected during the clinical study revealed stability of the nanocarrier in vivo. Thus, reliable and GMP-compliant production of anti-EGFR-targeted nanoparticles for clinical application is feasible.