Evaluation der pharmakologischen Wirkung des neuen Antimetabolit-Bisphosphonat-Konjugats 5-FdU-Alendronat auf die ossäre Metastasierung des Mammakarzinoms auf zellulärer Ebene sowie am kliniknahen Mausmodell

Ziel dieser Dissertation ist es, den neuen kombinierten Wirkstoff 2'-Desoxy-5-Fluoruridin-Alendronat (5-FdU-ale) anhand von in vitro und in vivo durchgeführten Versuchen auf seine Wirksamkeit gegenüber der Entstehung und des Wachstums von Knochenmetastasen beim metastasierenden Mammakarzinom zu testen. 5-FdU-ale setzt sich aus dem Zytostatikum 2'-Desoxy-5-Fluoruridin (5-FdU) und dem Aminobisphosphonat Alendronat zusammen. Dieses Molekül vereinigt somit die hohe Knochenaffiniät (bone targeting) des Alendronats und die zytostatische Komponente des 5-FdU in sich und wirkt so potentiell hochspezifisch und mit wenigen systemischen Nebenwirkungen gegen Knochenmetastasen. In vitro wurde an humanen Mammakarzinomzellen einerseits ein Zellviabilitätsassay (MTT-Test) zur Toxizitätsprüfung und andererseits eine FACS-Analyse zur Untersuchung der Auswirkungen der einzelnen Medikamente auf den Zellzyklus durchgeführt. Zur in vivo Evaluation wurde ein kliniknahes Mausmodell verwendet. Den Mäusen wurden zu Versuchsbeginn die humanen Mammakarzinomzellen intrakardial appliziert und so ein metastasierendes Tumorgeschehen imitiert. In wöchentlichen Intervallen wurden den Versuchstieren die Medikamente 5-FdU-ale, 5-FdU oder Alendronat gespritzt. Eine Kontrollgruppe erhielt keine Medikation. Nach 5 Wochen wurden die Tiere euthanasiert, ihre Seren gewonnen und Tibiae und Femora zur histologischen Aufarbeitung präpariert. Die entstandenen Knochenmetastasen der Knieregionen wurden anhand eines histomorphometrischen Verfahrens an histologischen Schnitten analysiert. Knochenstoffwechselparameter wie das osteoblastenspezifische Osteocalcin und die von aktivierten Osteoklasten gebildete Tartrat-resistente saure Phosphatase (TRAP) wurden anhand enzymatischer Immunadsorptionsverfahren aus den Seren der Tiere bestimmt. Die lokale Osteoklastenaktivität an der Tumor-Korikalis-Grenze wurde zusätzlich anhand einer immunhistochemischen TRAP-Färbung der Knochen bestimmt

Endogenous TRAIL-R4 critically impacts apoptotic and non-apoptotic TRAIL-induced signaling in cancer cells

Binding of TRAIL to its death domain-containing receptors TRAIL-R1 and TRAIL-R2 can induce cell death and/or pro-inflammatory signaling. The importance of TRAIL and TRAIL-R1/R2 in tumor immune surveillance and cancer biology has meanwhile been well documented. In addition, TRAIL has been shown to preferentially kill tumor cells, raising hope for the development of targeted anti-cancer therapies. Apart from death-inducing receptors, TRAIL also binds to TRAIL-R3 and TRAIL-R4. Whereas TRAIL-R3 is lacking an intracellular domain entirely, TRAIL-R4 contains a truncated death domain but still a signaling-competent intracellular part. It is assumed that these receptors have anti-apoptotic, yet still not well understood regulatory functions. To analyze the significance of the endogenous levels of TRAIL-R4 for TRAIL-induced signaling in cancer cells, we stably knocked down this receptor in Colo357 and MDA-MB-231 cells and analyzed the activation of apoptotic and non-apoptotic pathways in response to treatment with TRAIL. We found that TRAIL-R4 affects a plethora of signaling pathways, partly in an opposite way. While knockdown of TRAIL-R4 in Colo357 strongly increased apoptosis and reduced clonogenic survival, it inhibited cell death and improved clonogenic survival of MDA-MB-231 cells after TRAIL treatment. Furthermore, TRAIL-R4 turned out to be an important regulator of the expression of a variety of anti-apoptotic proteins in MDA-MB-231 cells since TRAIL-R4-KD reduced the cellular levels of FLIPs, XIAP and cIAP2 but upregulated the levels of Bcl-xL. By inhibiting Bcl-xL with Navitoclax, we could finally show that this protein mainly accounts for the acquired resistance of MDA-MB-231 TRAIL-R4-KD cells to TRAIL-induced apoptosis. Analyses of non-apoptotic signaling pathways revealed that in both cell lines TRAIL-R4-KD resulted in a constitutively increased activity of AKT and ERK, while it reduced AKT activity after TRAIL treatment

CDK4/6 Inhibitors in Advanced HR+/HER2 - Breast Cancer: A Multicenter Real-World Data Analysis

CDK4/6 inhibitors (CDK4/6i) combined with endocrine therapy are considered standard-of-care for first-line therapy of patients with hormone receptor positive, HER2 negative, advanced breast cancer (HR+/HER2- ABC). Superiority of combination therapy over endocrine monotherapy has been demonstrated in a multitude of randomized controlled trials (RCTs) in phase III and IV. However, RCTs reflect clinical reality only to a limited extent, as narrow inclusion criteria lead to a selected patient collective. Here, we present real-world data (RWD) on CDK4/6i treatment in patients with HR+/HER2- ABC at four certified German university breast cancer centers.This study was supported by Novartis Pharma GmbH as part of the “ERIC” (“Excellent Researchers in Breast Cancer”) project

ADAM17—A Potential Blood-Based Biomarker for Detection of Early-Stage Ovarian Cancer

Ovarian cancer has the highest mortality rate among gynecological tumors. This is based on late diagnosis and the lack of early symptoms. To improve early detection, it is essential to find reliable biomarkers. The metalloprotease ADAM17 could be a potential marker, as it is highly expressed in many solid tumors, including ovarian and breast cancer. The aim of this work is to evaluate the relevance of ADAM17 as a potential diagnostic blood-based biomarker in ovarian cancer. Ovarian cancer cell lines IGROV-1 and A2780, as well as primary patient-derived tumor cells obtained from tumor tissue and ascitic fluid, were cultured to analyze ADAM17 abundance in the culture supernatant. In a translational approach, a cohort of 117 well-characterized ovarian cancer patients was assembled and ADAM17 levels in serum and corresponding ascitic fluid were determined at primary diagnosis. ADAM17 was quantified by enzyme-linked immunosorbent assay (ELISA). In the present study, ADAM17 was detected in the culture supernatant of ovarian cancer cell lines and primary cells. In addition, ADAM17 was found in serum and ascites of ovarian cancer patients. ADAM17 level was significantly increased in ovarian cancer patients compared to an age-matched control group (p < 0.0001). Importantly early FIGO I/II stages, which would not have been detected by CA-125, were associated with higher ADAM17 concentrations (p = 0.007). This is the first study proposing ADAM17 as a serum tumor marker in the setting of a gynecological tumor disease. Usage of ADAM17 in combination with CA-125 and other markers could help detect early stages of ovarian cancer