Project Summary Due to their indolent nature, few cell lines or animal models have been established for chronic lymphocytic leukemia (CLL) and follicular lymphoma (FL) compared to other types of cancer. The primary goal of this proposal is to establish an ex vivo indolent lymphoma (iNHL) model that mimics the tumor in vivo microenvironment with faithful readouts of drug sensitivity/ resistance to enable personalized medicine. The central hypothesis is that an ex vivo model with tumor microenvironment (TME) mimicry would make iNHL behave physiologically and provide a clinical faithful model for drug testing. Guided by our preliminary data, the objective will be achieved by the following two specific aims: 1) To refine and build ex vivo iNHL models that will best support tumor cell in vivo behaviors; 2) To validate the models by correlating modeled drug response with patients’ clinical response and/or mutation profiles. In the first aim, optimized ex vivo iNHL models will be created by transducing bone marrow fibroblasts (BMF) with B-cell growth factors, mimicking different cell types found in the tumor milieu in the lymph nodes. Subsequent co-culture-induced changes in cellular behaviors will be measured including cell proliferation and adhesion that are rarely measured in the absence of suitable iNHL models. We then aim to demonstrate that the model is clinically relevant and potentially useful. We will correlate individual modeled cellular response with the clinical response and/or mutation profiles for 60 patients using each patient’s tumor cells to build a personalized therapeutic model. We believe the proposed study is innovative because a practical and clinically faithful personalized Rx model is currently non-existent for indolent lymphoma. It is anticipated that the eventual model will be fast, simple, and economical, enabling a personalized drug trial for individual patients. With the model, we seek to make a stride towards the reality of practicing personalized medicine in the clinic for the benefits of iNHL patients. Successful completion of the proposed research will deliver the following tangible benefits: 1) Models which recapitulate the iNHL-TME that enable evaluation of in vivo behaviors of refractory indolent lymphoma, not currently achievable with the lack of suitable models; 2) Practical (fast, simple, and economical) and clinically faithful models which may be used to guide individualized therapy selection in the clinic leading to direct patient benefits; 3) A large number of genetically heterogeneous tumor models which will streamline the efficiency of future drug development; and 4) A modeling approach potential applicable to other indolent as well as aggressive lymphomas.