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Background: VEGF-A is the most potent pro-angiogenic factor and is upregulated in a variety of tumors. Therapies were developed to neutralize VEGF signalling, such as Bevacizumab (Bev). Despite promising pre-clinical results, the average response rate to Bev is reduced for most cancers, with significant side effects. In breast cancer (BC) several studies and a meta-analysis have also confirmed a limited i efficacy in unselected populations. Lack of predictive biomarkers prevents a good patient selection. As such guidelines consider Bev only in a minority of cases. Additionally, depending on the individual tumor, VEGF-A can either block or promote metastasis. In this context, an assay able to predict individual responses to Bev, including its impact on metastasis would prove of great value. Methods: We developed an assay, using zebrafish xenografts(zX), where tumor response and the impact on angiogenesis and metastasis (mets) can be readily analysed. By using Triple negative BC (TNBC) cell line models (Hs578T and MDA-MB-468) and zebrafish patient derived xenografts(zPDX) we evaluated the impact of Bev on proliferation, apoptotis, tumor size, angiogenesis and metastasis. Results: a) Human TNBC cell lines display different tumoral features in zX: Hs578T presented the most vascularized tumors (vessel density ~32.4%) and the lowest metastatic capacity (2.6% of xenografts presented mets, n=77). In contrast, MDA-MB-468 that only recruits blood vessels to the base of the tumor, showed a higher metastatic potential (42.5%, n=87). No direct correlation between vessel density and metastasis could be seen. b) zX were able to reveal different individual tumor responses to Bev in 4 days. Analysis of cell death revealed higher apoptosis rate in Hs578T xenografts (1.6-fold, p Conclusions: Our results show that the zebrafish larvae xenografts have enough resolution to display differential tumor responses to Bev in TNBC models and zPDX in just 4 days. We propose zebrafish cancer xenografts as a promising fast in vivo platform for Bev screening, allowing analysis of personalized responses. Citation Format: Cátia Almeida, Raquel Mendes, Joana Mourato Ribeiro, Maria João Cardoso, Fátima Cardoso, Miguel Godinho Ferreira, Rita Fior. Zebrafish xenografts as a fast screening platform for bevacizumab impact on tumor growth, angiogenesis and micrometastasis in breast cancer [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P1-03-04.

Cancer is as unique as the person fighting it. With the exception of a few biomarker-driven therapies, patients go through rounds of trial-and-error approaches to find the best treatment. Using patient-derived cell lines, we show that zebrafish larvae xenotransplants constitute a fast and highly sensitive in vivo model for differential therapy response, with resolution to reveal intratumor functional cancer heterogeneity. We screened international colorectal cancer therapeutic guidelines and determined distinct functional tumor behaviors (proliferation, metastasis, and angiogenesis) and differential sensitivities to standard therapy. We observed a general higher sensitivity to FOLFIRI [5-fluorouracil(FU)+irinotecan+folinic acid] than to FOLFOX (5-FU+oxaliplatin+folinic acid), not only between isogenic tumors but also within the same tumor. We directly compared zebrafish xenografts with mouse xenografts and show that relative sensitivities obtained in zebrafish are maintained in the rodent model. Our data also illustrate how KRAS mutations can provide proliferation advantages in relation to KRASWT and how chemotherapy can unbalance this advantage, selecting for a minor clone resistant to chemotherapy. Zebrafish xenografts provide remarkable resolution to measure Cetuximab sensitivity. Finally, we demonstrate the feasibility of using primary patient samples to generate zebrafish patient-derived xenografts (zPDX) and provide proof-of-concept experiments that compare response to chemotherapy and biological therapies between patients and zPDX. Altogether, our results suggest that zebrafish larvae xenografts constitute a promising fast assay for precision medicine, bridging the gap between genotype and phenotype in an in vivo setting. info:eu-repo/semantics/publishedVersion

Summary The stereotypic left-right (LR) asymmetric distribution of internal organs is due to an asymmetric molecular cascade in the lateral plate mesoderm (LPM) that is originated at the embryonic node. In chicken embryos, molecular asymmetries at Hensen's node are created by leftward cell movements that occur transiently. What terminates these movements, and, moreover, what is the impact of prolonging them on the LR asymmetry cascade? We show that leftward movements last longer when N-cadherin function is blocked and cease prematurely when N-cadherin is overexpressed on the right side of the node. The prolonged leftward movements lead to loss of asymmetric expression of fgf8 and nodal at the node region. This originates an abnormal expression of the asymmetric genes cer1 and snai1 in the LPM, resulting in mispositioned hearts. We conclude that N-cadherin stops the leftward cell movements and that this termination is an essential step in the establishment of LR asymmetry.