Patient-derived xenograft platform for metastatic melanoma: a model for studying resistance to targeted therapy.

The therapeutic landscape of melanoma is rapidly changing. While targeted inhibitors yield significant responses, their clinical benefit is often limited by the early onset of drug resistance. This motivates the pursuit to establish more durable clinical responses, by developing combinatorial therapies. But while potential new combinatorial targets steadily increase in numbers, they cannot possibly all be tested in patients. Similarly, while genetically engineered mouse melanoma models have great merit, they do not capture the enormous genetic diversity and heterogeneity typical in human melanoma. Furthermore, whereas in vitro studies have many advantages, they lack the presence of micro-environmental factors, which can have a profound impact on tumor progression and therapy response. This prompted us to develop an in vivo model for human melanoma that allows for studying the dynamics of tumor progression and drug response, with concurrent evaluation and optimization of new treatment regimens. Here, we present a collection of patient-derived xenografts (PDX), derived from BRAFV600E, NRASQ61 or BRAFWT/NRASWT melanoma metastases. The BRAFV600E PDX melanomas were acquired both prior to treatment with the BRAF inhibitor vemurafenib and after resistance had occurred, including six matched pairs. We find that PDX resemble their human donors' melanomas regarding biomarkers, chromosomal aberrations, RNA expression profiles, mutational spectrum and targeted drug resistance patterns. Mutations, previously identified to cause resistance to BRAF inhibitors, are captured in PDX derived from resistant melanomThis melanoma PDX platform represents a comprehensive public resource to study both fundamental and translational aspects of melanoma progression and treatment in a physiologically relevant setting. Overall design: Melanoma samples pre and post Vemurafenib treatment from patient and matching patient derived xenografts (PDX)

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Kluin RJC, Kemper K, Kuilman T, de Ruiter JR, Iyer V, Forment JV, Cornelissen-Steijger P, de Rink I, Ter Brugge P, Song JY, Klarenbeek S, McDermott U, Jonkers J, Velds A, Adams DJ, Peeper DS, Krijgsman O