FLOW CYTOMETRY SHARED RESOURCE (FCSR) ABSTRACT The UCLA Jonsson Comprehensive Cancer Center (JCCC) Flow Cytometry Shared Resource (FCSR) provides continuously updated, state-of-the-art instrumentation, expertise, and training at a reduced recharge rate to JCCC investigators whose research requires flow cytometry, mass cytometry, imaging cytometry, or cell sorting. The FCSR is one of the longest running core facilities at UCLA and it has been servicing the needs of the JCCC cancer research community since its inception in 1988. In 2015, Zoran Galic, PhD (ZY) became the FCSR Director and he oversees all of the operations of the facility. Alejandro Garcia, PhD, FCSR Co-Director and Facility Manager, is responsible for FCSR daily operations and assists Galic with long-term core planning. The FCSR currently houses an ImageStream imaging cytometer, a Helios mass cytometer, an Attune NxT flow cytometer, two LSR II cell analyzers, an LSR Fortessa cell analyzer, three Aria high-speed cell sorters, one of which is enclosed in a biocontainment hood, and a RoboSep magnetic cell separator. The FCSR also established a separate office for data analysis with two high-end computer workstations capable of processing large data sets generated by the ImageStream imaging cytometer. FCSR personnel have >80 years of combined flow cytometry experience and they provide expert guidance to JCCC investigators through one-on-one consultations, educational classes, an information-rich website, and “how-to” poster presentations. Workshops, seminars, and tutorials organized by the FCSR ensure that researchers remain on the leading edge of cytometry. The FCSR has a broad user base and during 2013 – 2018, the FCSR supported many JCCC investigator projects from all six JCCC Research Programs. JCCC member usage is 78% of the total Shared Resource usage. FCSR support activities helped to enable 333 publications, of which 175 (53%) were in high-impact (IF ≥10, or field leading) journals. FCSR leaders work with the Dean’s office in the David Geffen School of Medicine and additional centers on campus to contain costs and provide high quality services for JCCC investigator studies. During the prior project period, the FCSR supported numerous JCCC research teams to advance impactful preclinical studies to the clinic. One inter-programmatic investigation showed that a combination of an immune checkpoint inhibitor with BRAF plus MEK signaling pathway inhibitors in a mouse model of BRAF-mutant melanoma was superior to either treatment alone. Based on these results, two Phase I clinical trials and three larger industry sponsored randomized trials are underway. Separately, the FCSR supported intra-programmatic preclinical studies on checkpoint inhibitors and dendritic cell vaccines in a mouse model of intracranial glioma. Based on this work a randomized, multi-institution trial established that neoadjuvant pembrolizumab significantly extended patients overall survival compared to a control gr...