Pilot Prospective Study for PET-CT Imaging in Participants With Relapsed/Refractory Acute Leukemias

Background * Acute lymphoblastic leukemia (ALL) is the most common pediatric malignancy, accounting for approximately 25 percent of all childhood cancer. ALL also spans the age spectrum and represents approximately 20 percent of adult leukemias. * Despite improved survival rates for pediatric, adolescent, and adult ALL, relapse following upfront therapy is common. The recent introduction of chimeric antigen receptor (CAR) T-cell therapies has improved outcomes compared to other available salvage regimens, but limitations to its efficacy exist. * The presence of non-central nervous system (CNS) extramedullary disease (EMD) at the time of CAR T-cell infusion is associated with lower complete remission (CR) rates compared to isolated medullary disease even with evidence of CAR trafficking to EMD sites. Despite implications for CAR therapy, the true incidence of non-CNS EMD for patients proceeding to CAR is unknown. Our retrospective study estimates the EMD rate to be as high as 21 percent. * Although 18-fludeoxyglucose (18F-FDG) positron emission tomography-computed tomography (PET-CT) is feasible and has been shown to be high yield for detection of non-CNS EMD in ALL, it is not part of standard evaluation pre-CAR T-cell therapy. * Recent studies examining the use of pre and post-infusion FDG PET-CT in patients with large cell lymphoma treated with CAR have shown Deauville response criteria, total metabolic tumor volume, and change of standardized uptake values (SUV) to be predictive of CAR T outcomes and risk of early progression. In addition to the use of PET-CT in monitoring CAR T response, circulating tumor DNA (ctDNA) has been shown risk stratify and predict outcomes in large cell lymphoma and can be detected prior to radiographic evidence of relapse. Objectives -Describe the proportion of non-CNS EMD in adult participants with relapsed/refractory BALL proceeding to CAR T-cell therapy Eligibility * Participants \>=18 years with relapsed/refractory B cell ALL who are being screened for CAR T-cell clinical trial enrollment, and * Participants \<18 with relapsed/refractory B cell ALL who are being screened for CAR T-cell clinical trial enrollment and have a clinical indication for FDG PET-CT prior to CAR infusion. Design -Pilot study to add screening FDG PET-CT as part of the pre-CAR T-cell baseline evaluation with additional imaging at day 28 and future timepoints pending evidence of non-CNS EMD on initial scan.