Preclinical targeting of the tumor microenvironment:Possibilities and consequences

Gemetastaseerde ziekte is momenteel de hoofdoorzaak van alle aan kanker gerelateerde sterfte. Dit onderstreept het belang van het vinden van nieuwe behandelstrategieën. Onlangs bleek dat het normale weefsel dat de tumor omgeeft, de tumormicro-omgeving, een belangrijke rol speelt bij tumorgroei en metastasering. Door nieuwe behandelopties te richten tegen zowel de kankercellen als de tumormicro-omgeving, kan de effectiviteit van huidige therapieën mogelijk worden verbeterd. Voor de ontwikkeling van een dergelijke nieuwe behandeloptie, is het noodzakelijk om moleculaire factoren in de tumormicro-omgeving te identificeren. Twee potentiële factoren zijn transforming growth factor (TGF)-β en vascular endothelial growth factor (VEGF). In preklinische modellen bestaande uit stromale- en borstkankercellen wordt de tumor met zijn micro-omgeving nagebootst. Deze in vitro en in vivo modellen laten zien dat stromale cellen nodig zijn voor het TGF-β gemedieerde anti-borstkankereffect van het bisfosfonaat zoledronaat. Daarnaast wordt de preklinische ontwikkeling van een TGF-β tracer beschreven. Bij deze techniek wordt een radioactief gelabeld antilichaam afgebeeld met positron emissie tomografie (PET). Middels deze TGF-β tracer kon de aanwezigheid van TGF-β in tumoren worden afgebeeld. Voor VEGF werd het effect van anti-VEGF therapie op geneesmiddelopname geëvalueerd met behulp van PET beeldvorming. Anti-VEGF therapie vermindert de opname van andere geneesmiddelen in twee verschillende preklinische modellen. Concluderend beschrijft dit proefschrift preklinisch onderzoek naar de mogelijkheden en consequenties van therapieën gericht op factoren in de tumormicro-omgeving

Human stromal cells are required for an anti-breast cancer effect of zoledronic acid

Previous studies suggested that bisphosphonate zoledronic acid exerts an antitumor effect by interacting with the microenvironment. In this study, we aimed to elucidate the mechanism behind the anti-breast cancer effect of zoledronic acid.Here we showed that zoledronic acid did not influence in vitro human breast cancer cell survival, but did affect human stromal cell survival. Breast cancer cell death in co-culture with stromal cells was analyzed in vitro by fluorescent microscopy and flowcytometry analysis. In co-culture, the addition of stromal cells to breast cancer cells induced tumor cell death by zoledronic acid, which was abolished by transforming growth factor (TGF)-beta. In the in vivo chicken chorioallantoic membrane model, zoledronic acid reduced the breast cancer cells fraction per tumor only in the presence of human stromal cells. Zoledronic acid decreased TGF-beta excretion by stromal cells and co-cultures. Moreover, supernatant of zoledronic acid treated stromal cells reduced phospho-Smad2 protein levels in breast cancer cells. Thus, zoledronic acid exerts an anti-breast cancer effect via stromal cells, accompanied by decreased stromal TGF-beta excretion and reduced TGF-beta signaling in cancer cells.</p

VEGF pathway targeting agents, vessel normalization and tumor drug uptake:from bench to bedside

Vascular endothelial growth factor (VEGF) pathway targeting agents have been combined with other anticancer drugs, leading to improved efficacy in carcinoma of the cervix, stomach, lung, colon and rectum, ovary, and breast. Vessel normalization induced by VEGF pathway targeting agents influences tumor drug uptake. Following bevacizumab treatment, preclinical and clinical studies have shown a decrease in tumor delivery of radiolabeled antibodies and two chemotherapeutic drugs. The decrease in vessel pore size during vessel normalization might explain the decrease in tumor drug uptake. Moreover, the addition of bevacizumab to cetuximab, or panitumumab in colorectal cancer patients or to trastuzumab in breast cancer patients, did not improve efficacy. However, combining bevacizumab with chemotherapy did increase efficacy in some cancer types. Novel biomarkers to select patients who may benefit from combination therapies, such as the effect of an angiogenesis inhibitor on tumor perfusion, requires innovative trial designs and large clinical trials. Small imaging studies with radiolabeled drugs could be used in the interphase to gain further insight into the interplay between VEGF targeted therapy, vessel normalization and tumor drug delivery

Adipose tissue supernatant of overweight ER positive breast cancer patients promotes migration of MCF-7 breast cancer cells

Introduction: Adipose tissue is a major component of the breast cancer microenvironment, and preclinical studies have suggested that adipose tissue might play a pivotal role in breast cancer progression. In this study we investigated the effect of adipose tissue from patients with ER positive breast cancer on migration of ER positive MCF-7 breast cancer cells. Materials and Methods: Adipose tissue samples were collected from patients with ER positive breast cancer undergoing a mastectomy. In total, adipose tissue samples from 3 normal weight (BMI: 18.5-24.9) and 7 overweight breast cancer patients (BMI: 25-29.9) were collected. Samples from the mastectomy specimens were minced in small pieces, incubated in RPMI-1640 and after 48 hours (h) the supernatant was harvested. The effect of adipose tissue supernatant on the migration of MCF-7 cells was monitored in real-time for 48 h with the xCELLigence cell invasion and migration plates expressed in delta cell index (DCI). In addition, effect of adipose tissue supernatant on migration was assessed by quantification of F-actin positive lamellipodia of MCF-7 cells in a scratch assay after 24 h. In all experiments, RPMI-1640 with 1% or 20% FCS was used as a negative or positive control respectively. Results: Supernatant of overweight patients significantly induced MCF-7 migration compared to supernatant of normal weight patients after 24 h (xCELLigence DCI: 1.22 ± 0.15 vs. 0.95 ± 0.19 (P=0.038)), 36 h (DCI 1.40 ± 0.21 vs. 0.91 ± 0.31 (P=0.019)) and 48 h (DCI 1.72 ± 0.23 vs. 0.98 ± 0.43 (P=0.007)). In addition, there was a significant difference between the overweight group and negative control at 36 h, and 48 h (DCI 1.40 ± 0.21 vs. 1.06 ± 0.12, P=0.038 and DCI 1.72 ± 0.23 vs. 1.11 ± 0.21, P=0.004 respectively). No significant difference between normal weight group and negative control was found at any of the time points. After 24 h MCF-7 cells incubated with supernatant of overweight patients developed significantly more F-actin positive lamellipodia compared to MCF-7 cells incubated with supernatant of normal weight patients (44.26 ± 3.26% vs. 25.47 ± 1.88% P&lt;0.001). Conclusion: In this study, we showed that adipose tissue supernatant of patients with ER positive breast cancer can promote migration of MCF-7 breast cancer cells in a weight dependent manner. Whether this is the case in other breast cancer subtypes as well, and the potential clinical implication, is of interest for future studies. Citation Format: Jie Ma, Hetty Timmer-Bosscha, Paul M. Werker, Carolina P. Schröder, Marlous Arjaans. Adipose tissue supernatant of overweight ER positive breast cancer patients promotes migration of MCF-7 breast cancer cells [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 4002

Transforming growth factor (TGF)-beta expression and activation mechanisms as potential targets for anti-tumor therapy and tumor imaging

Cancer remains one of the leading causes of death in the developed countries and cancer mortality is expected to rise globally. Despite encouraging developments regarding targeted drugs, the most prevalent cancer mortality remains metastatic disease. Therefore, drugs that target cancer progression, invasion and metastasis are clearly needed. One of the most interesting targets in this setting is transforming growth factor beta (TGF-beta). TGF-beta can promote tumor growth, invasion and metastasis. However, TGF-beta also has a physiological, opposing role: maintaining tissue homeostasis and suppression of tumor progression. The window of effective TGF-beta targeting is therefore evidently small, which poses a clear challenge in selecting patients at the right time. Despite this complexity, several TGF-beta inhibitors are currently in clinical development, modulating TGF-beta production, activation or signaling. Still, specificity and long term toxicity remain unclear, emphasizing the importance of careful monitoring of clinical trials. Development and application of these drugs in the clinic require adequate insight and evaluation methods for the role of TGF-beta during tumor invasion and metastasis. In this review, presently available methods for clinical evaluation will be discussed, such as an ex vivo stimulation assay, TGF-beta response signature and molecular imaging techniques. Future clinical trials incorporating the validation of these evaluation methods will show which method will be most predictive and suitable for clinical application. (C) 2012 Elsevier Inc. All rights reserved

Bevacizumab-Induced Normalization of Blood Vessels in Tumors Hampers Antibody Uptake

<p>In solid tumors, angiogenesis occurs in the setting of a defective vasculature and impaired lymphatic drainage that is associated with increased vascular permeability and enhanced tumor permeability. These universal aspects of the tumor microenvironment can have a marked influence on intratumoral drug delivery that may often be underappreciated. In this study, we investigated the effect of blood vessel normalization in tumors by the antiangiogenic drug bevacizumab on antibody uptake by tumors. In mouse xenograft models of human ovarian and esophageal cancer (SKOV-3 and OE19), we evaluated antibody uptake in tumors by positron emission tomographic imaging 24 and 144 hours after injection of Zr-89-trastuzumab (SKOV-3 and OE19), Zr-89-bevacizumab (SKOV-3), or Zr-89-IgG (SKOV-3) before or after treatment with bevacizumab. Intratumor distribution was assessed by fluorescence microscopy along with mean vessel density (MVD) and vessel normalization. Notably, bevacizumab treatment decreased tumor uptake and intratumoral accumulation compared with baseline in the tumor models relative to controls. Bevacizumab treatment also reduced MVD in tumors and increased vessel pericyte coverage. These findings are clinically important, suggesting caution in designing combinatorial trials with therapeutic antibodies due to a possible reduction in tumoral accumulation that may be caused by bevacizumab cotreatment. (C) 2013 AACR.</p>