LAUSR

Background & Aim Background Reduced CD34 cell viability following cryopreservation is associated with suboptimal engraftment in stem cell transplantation. Collection of extra hematopoietic progenitor cells (HPC) can compensate for the potential loss, but subjects patients to unnecessary procedures, and drives up healthcare costs. Aim The goal of this study was to identify variables available on the day of HPC collection that help predict the likelihood of a significant post-thaw drop in viable CD34 cells (vCD34). A prediction model was generated to recommend appropriate extra-day collections. Methods, Results & Conclusion Methods We collected data on 235 consecutive autologous HPC apheresis collections in a single pediatric hospital and analyzed variables that are patient-related, product-related, and technical in nature (Table 1). Both continuous and discrete variables were analyzed and used to construct a prediction model with a false negative rate (missing a call to predict a significant drop in vCD34%) of zero. Results In 5.5% of apheresis products, post-thaw vCD34% decreased by >50%, 15% had 25-50% drop, 29% showed 50%) post-thaw vCD34% decrease included a diagnosis of Hodgkin lymphoma and a low mononuclear cell (MNC) percentage. A simple algorithm combining these three factors correctly identified 9 out of 11 (81%) unnecessary repeat collections, and did not miss any patients for whom a recollection was necessary. Retrospective analysis suggests that using this algorithm, 33% of repeat collections could be avoided. Conclusion Low CD45 nMFI of CD34+ cells is a novel marker of poor post-thaw CD34 cell recovery. A predictive model that combines CD45 nMFI, Hodgkin lymphoma disease status, and MNC percentage has shown good power for predicting unnecessary repeat collections in our patient population. Our predictive model of post-thaw CD34 cell recovery, implemented as a clinical support tool, could help spare unnecessary procedures in a significant percentage of patients. Prospective validation of the algorithm is ongoing, and data will be presented at the meeting.