Abstracts Clinical Lymphoma, Myeloma & Leukemia September 2023 S442 diffuse large B-cell lymphoma (DLBCL). The benefit of ibrutinib in relapsed/refractory PCNSL was weighed against the MTX toxicity profile in elderly patients. We initiated ibrutinib+rituximab while inpatient and continued oral ibrutinib therapy upon discharge. He demonstrated clinical improvement, shrinkage of brain lesions on MRI, and PET negativity. Conclusions: Our approach can be replicated at other institutions with repeat occurrences of drug shortages to ensure equitable distribution to avoid delays and lack of treatment. Weekly or more frequent pharmacy-led communications and open dialogue amongst specialists provide a sound approach to triaging chemotherapies during shortages. Specifically for CNS lymphoma/leukemia, reasonable regimens to consider are rituximab-Ara-C for younger, fit patients, and ibrutinib±rituximab for older, less fit patients. Keywords: aggressive B-cell lymphoma, ABCL, methotrexate shortage, PCNSL, CNS lymphoma/leukemia, ibrutinib, cytarabine (ara-c) ABCL-600 Diagnostic Utility of the 18F‑FDG PET/CT Scan in EBV‑Positive Solid Organ Transplant Patients at Risk for Post‑Transplant Lymphoproliferative Disorder Hua-Jay Cherng MD, Kathleen Capaccione MD, PhD, Hong Ma MD, Sachin Jambawalikar PhD, Evelyn Orlando MD, Maegan Ford MD, MPH, Patrick Gould MD, Brian Cuzzo MD, Andrew Lipsky MD, Barbara Pro MD, Jennifer Amengual MD Columbia University Medical Center, New York, USA Post-transplant lymphoproliferative disorder (PTLD) is a major complication and source of morbidity and mortality following solid organ transplantation (SOT). Epstein-Barr virus (EBV) infection in B-cells that proliferates in the setting of posttransplant immunosuppression is a major contributing factor to PTLD. Early detection and pathologic confirmation of PTLD are pivotal for successful treatment. Unfortunately, PTLD spans a heterogenous spectrum of diseases and subtypes with oftentimes nonspecific clinical presentations. 18F-flurodeoxyglucose-positron emission tomography/computed tomography (18F-FDG PET/ CT) is a powerful diagnostic modality in PTLD because of its high sensitivity for lymphomatous infiltration. 18F-FDG PET/CT scans are often performed at our center in the setting of concerning EBV reactivation which raises a clinical suspicion for PTLD. However, SOT patients are also at risk for non-PTLD causes of 18F-FDGavid lesions, such as atypical infections, other malignancies, or benign reactive lymph node changes. Furthermore, the frequent extranodal presentation of PTLD can lead to suboptimal detection in these cases. This study was designed to characterize the diagnostic performance of 18F-FDG PET/CT in EBV+ SOT patients at risk for PTLD, including the utility of standard and novel radiographic metrics. We identified 2273 patients with no age exclusions who received a SOT at our institution and subsequently developed EBV viremia after 2010, then identified patients who had an 18F-FDG PET/CT scan performed for suspicion or staging of newly diagnosed PTLD. Patients with scans performed for unrelated reasons or those with confirmed PTLD who only had scans after treatment were excluded. In total, we identified 135 patients with a pathologic diagnosis of PTLD and a baseline 18F-FDG PET/CT and another 109 patients who had an 18F-FDG PET/CT performed for PTLD workup but were never diagnosed with PTLD during follow-up. A total of 1836 SOT patients without PTLD were never worked up with an 18F-FDG PET/CT scan. Of these, 153/1836 (8%) patients received rituximab without a scan for various reasons, including EBV viremia or allograft rejection. Analyses on the sensitivity and specificity of 18F-FDG PET/CT scans for PTLD and qualitative, semi-quantitative, and radiomics features with respect to diagnostic performance are planned. Keywords: post-transplant lymphoproliferative disorder, PET/CT scan, diagnosis, EBV ABCL-612 Real‑World Outcomes in Patients With Relapsed or Refractory (r/r) Aggressive Large B‑Cell Lymphoma (LBCL) Treated With Chemo‑Immunotherapy Loretta J. Nastoupil MD1, Clark Andersen MS1, Amy Ayers MPH1, Yucai Wang MD, PhD2, Thomas M. Habermann MD2, Dai Chihara MD, PhD1, Brad S. Kahl MD3, Brian K. Link MD4, Sabarish Ayyappan MD4, Jonathon B. Cohen MD5, Peter Martin MD6, Izidore S. Lossos MD7, Carla Casulo MD8, Ruitao Lin PhD1, Ziyi Li PhD, MPH1, Melissa A. Larson MS2, Matthew J. Maurer DMSc2, Lynn Huynh DrPH, MPH, MBA9, Chi Gao DSc9, Ramya Ramasubramanian PhD, MPH9, Mei Sheng Duh DSc, MPH9, Alex Mutebi PhD10, Tongsheng Wang MSc, MS10, Monika Jun MPH10, Anthony Wang PhD, MPH11, Rajesh Kamalakar MS11, Anupama Kalsekar PhD10, James R. Cerhan MD, PhD2, Christopher R. Flowers MD1 1MD Anderson Cancer Center, Houston, USA. 2Mayo Clinic, Rochester, USA. 3Washington University School of Medicine in St. Louis, St. Louis, USA. 4University of Iowa Carver College of Medicine, Iowa City, USA. 5Emory University, Atlanta, USA. 6Weill Medical College of Cornell Medicine, New York, USA. 7University of Miami Health System, Miami, USA. 8University of Rochester Medical Center, Rochester, USA. 9Analysis Group, Inc., Boston, USA. 10Genmab, Princeton, USA. 11AbbVie, Inc., Chicago, USA Objective: The treatment landscape for LBCL has evolved dramatically in recent years with the introduction of chimeric antigen receptor (CAR) T-cell therapy and novel agents. However, chemo-immunotherapy (CIT) remains a standard of care (SOC) for patients with r/r disease after ≥2 previous lines of therapy. This study characterized real-world clinical outcomes of LBCL patients who received CIT in the third or later line (3L+) of therapy. Design: A multi-site retrospective observational study was conducted using data for patients in the Lymphoma Epidemiology of Outcomes (LEO) Consortium of Real-World Evidence (CReWE) cohort (1/1/2015–2/15/2023) who were treated with CIT in 3L+ at one of eight academic centers. CIT regimens included salvage/ palliative
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