Wednesday, May 27, 2015

A simple model-based approach to inferring and visualizing cancer mutation signatures

A simple model-based approach to inferring and visualizing cancer mutation signatures

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Saturday, May 23, 2015

Cancer therapeutic potential of combinatorial immuno- and vaso-modulatory interventions

Cancer therapeutic potential of combinatorial immuno- and vaso-modulatory interventions 

H. Hatzikirou, J. C. L. Alfonso, S. Muhle, C. Stern, S. Weiss, M. Meyer-Hermann

Currently, most of the basic mechanisms governing tumor-immune system interactions, in combination with modulations of tumor-associated vasculature, are far from being completely understood. Here, we propose a mathematical model of vascularized tumor growth, where the main novelty is the modelling of the interplay between functional tumor vasculature and effector recruitment dynamics. Parameters are calibrated on the basis of different in vivo Rag1-/- and wild-type (WT) BALB/c murine tumor growth experiments. The model analysis supports that vasculature normalization can be a plausible and effective strategy to treat cancer when combined with appropriate immuno-stimulation. We find that improved levels of functional vasculature, potentially mediated by vascular normalization or stress alleviation strategies, can provide beneficial outcomes in terms of tumor burden reduction and control. Normalization of tumor blood vessels opens a therapeutic window of opportunity to augment the anti- tumor immune responses, as well as to reduce the intratumoral immunosuppression and hypoxia due to vascular abnormalities. The potential success of normalizing tumor vasculature closely depends on the effector cell recruitment dynamics and tumor sizes. Furthermore, an arbitrary increase of initial effector cell concentration does not necessarily imply tumor control, and we evidence the existence of an optimal effector concentration range for tumor shrinkage. Based on these findings, we suggest a theory-driven therapeutic proposal that optimally combines immune- and vaso-modulatory interventions.

Thursday, May 21, 2015

A non-local model for cancer stem cells and the tumor growth paradox

A non-local model for cancer stem cells and the tumor growth paradox

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Tuesday, May 5, 2015

A stochastic individual-based model for immunotherapy of cancer

A stochastic individual-based model for immunotherapy of cancer

Martina Baar, Loren Coquille, Hannah Mayer, Michael Hölzel, Meri Rogava, Thomas Tüting, Anton Bovier 

 

We propose an extension of a standard stochastic individual-based model in population dynamics which broadens the range of biological applications. Our primary motivation is modelling of immunotherapy for malignant tumors. The main characteristics of the model are distinguishing phenotype and genotype, including environment-dependent transitions between phenotypes that do not affect the genotype, and the introduction of a competition term which lowers the reproduction rate of an individual in addition to the usual term that increases its death rate. We prove that this stochastic process converges in the limit of large populations to a deterministic limit which is the solution to a system of quadratic differential equations. We illustrate the new setup by using it to model various phenomena arising in immunotherapy. Our aim is twofold: on the one hand, we show that the interplay of genetic mutations and phenotypic switches on different timescales as well as the occurrence of metastability phenomena raise new mathematical challenges. On the other hand, we argue why understanding purely stochastic events (which cannot be obtained with deterministic systems) may help to understand the resistance of tumors to various therapeutic approaches and may have non-trivial consequences on tumor treatment protocols and demonstrate this through numerical simulations.

http://arxiv.org/abs/1505.00452