THE THROMBOCYTOPENIA CASE STUDY 36.4 Modeling drug effects on thrombopoiesis 36.4.1 Toxicity modeling: IL-11 36.4.2 Efficacy modeling: Thrombopoietin (TPO) 36.4.3 Modeling combination therapy: Chemotherapy and TPO support 36.5 Using the validated model for improving drug efficacy/toxicity profile 36.5.1 Model validation using retrospective human study results: IL-11 and TPO 36.5.2 Model validation in prospective animal trials: TPO applied to the Virtual Mouse and Virtual Monkey 36.5.3 Predicting the optimal toxicity/efficacy ratio in monkeys: TPO 36.6 Using the thrombopoiesis model for predicting an unknown animal toxicity mechanism 36.7 Transition to Phase I 36.8 Conclusion References 36.1 36.1.1 Biomathematics and its use for rationalizing drug treatment strategies: a short historyA new synthesis of ecology and 'hard' biology, called biomathematics, emerged in the second half of the 20th century in the scientific community. Its role was to rationalize complex biological processes. Thus, in contrast to experimental biologists, who work at the microscopic cellular level and develop analytic tools that are analogous to the stills camera in photography, biomathematicians develop formulae, which effectively animate these shots, allowing us to understand the dynamics of the complex process we are investigating. Biomathematics has enabled the development of a range of new theories dealing with significant problems of disease progression and control, hitherto beyond the reach of 'snap shot', experimental biology.