LAUSR

e14019 Background: Axi-cel is an anti-CD19 CAR T-cell therapy that can lead to long term disease control for patients with refractory LBCL including DLBCL, PMBCL, HGBL, and tFL. Beyond day 30, grade 3 or higher cytopenias were reported in 17% of patients (Locke 2019). We sought to further characterize cytopenias after axi-cel. Methods: We evaluated patients with LBCL treated with axi-cel at Moffitt from May 2015 to May 2018. Counts at apheresis and days 30, 90 and 180 after axi-cel infusion were recorded. Data was censored at date of progression, death or last follow-up. AEs were per CTCAE v4.03. Results: 52 patients were identified. Count data at each time is presented in the table. In total, 37.8% (17/45), 17.8% (8/45), and 28.9% (13/45) of patients experienced any grade 3-4 neutropenia, anemia or thrombocytopenia beyond day 30. Beyond day 30: 24.4% (11/45) received G-CSF; one (2.2%) received a TPO-agonist; none received an EPO-agonist; 15.6% (7/45) IVIG; 11.1% (5/45) PRBC; and 8.9% (4/45) platelet transfusion. 11 patients had bone marrow biopsies to evaluate cytopenias, at a median of 50 days (range 29-434) following axi-cel infusion. Median cellularity was 16.3% (range 5-45%), and 3/11 had reticulin staining indicating fibrosis. One patient, previously reported (Locke, Mol. Ther, 2017), had therapy related MDS and evidence of prior CHIP mutation. Conclusions: Prolonged neutropenia, lymphopenia, anemia, and thrombocytopenia occurred at least 180 days following axi-cel therapy in LBCL patients, in the absence of disease progression. Transfusion burden was low, and most patients recovered without an intervention.[Table: see text]