The Public Repository of Xenografts enables discovery and randomized phase II-like trials in mice

More than 90% of drugs with preclinical activity fail in human trials, largely due to insufficient efficacy. We hypothesized that adequately powered trials of patient-derived xenografts (PDX) in mice could efficiently define therapeutic activity across heterogeneous tumors. To address this hypothesis, we established a large, publicly available repository of well-characterized leukemia and lymphoma PDXs that undergo orthotopic engraftment, called the Public Repository of Xenografts (PRoXe). PRoXe includes all de-identified information relevant to the primary specimens and the PDXs derived from them. Using this repository, we demonstrate that large studies of acute leukemia PDXs that mimic human randomized clinical trials can characterize drug efficacy and generate transcriptional, functional, and proteomic biomarkers in both treatment-naive and relapsed/refractory disease

Complex Interactions in Student Teaching: Lost Opportunities for Learning

Student teaching is a cornerstone of teacher preparation, yet it remains one of the most difficult experiences to understand. Calls for an ecological approach to research on student teaching prompted this study in which the experience is examined from the perspective of the three key triad members. Using activity theory, this study explores how their interactions in specific contexts shaped opportunities for student teachers to learn to teach language arts. The findings reveal that all members of the triad were simultaneously operating in multiple settings and facing competing demands that shaped their actions and stances. Consequently, there were numerous instances of lost opportunities for student teachers to learn to teach, including sparse feedback on teaching subject matter and few links to methods courses, plus limited opportunities to develop identities as teachers. The structures that frame student teaching and its participants have deep roots in the cultures of universities and schools that must be considered if student teaching is to maximize its potential