Cytopenias after Chimeric Antigen Receptor T-Cells (CAR-T) Infusion; Patterns and Outcomes

Patients with relapsed/refractory diffuse large B-cell lymphoma (DLBCL) have poor treatment outcomes when treated with traditional chemoimmunotherapy. Superior outcomes have been observed with the 2 CAR-T cell products approved by the US FDA; tisagenlecleucel (CTL109) and axicabtagene ciloleucel (Axi-cel) with 12 months overall survival rates of 49% and 59% respectively. The 2 major acute toxicities of these therapies are cytokine release syndrome (CRS) and neurotoxicity. The incidence of grade 3 or higher neutropenia, anemia, and thrombocytopenia was 78%, 43%, and 38% in patients treated with axi-cel. Little is known regarding the patterns and outcomes of these cytopenias. Here we present our preliminary experience on the patterns and outcomes of cytopenias in 32 patients who received commercially-available CAR-T cell therapy at our institution. We retrospectively reviewed all DLBCL patients receiving either CTL109 or axi-cel between January and September 2018 at our institution. All patients received a conditioning regimen of low-dose cyclophosphamide and fludarabine, followed by CAR-T infusion. Persistent cytopenias were defined as incomplete absolute neutrophil count ( 9 /L), Hb ( 9 /L) recovery after day 28 of CAR-T cell infusion. Treatment response was assessed with PET-CT imaging and classified according to International Working Group Criteria. The median age of patients was 59 years (range, 23-80); 63% were male, 4 patients (13%) received CTL109 and 28 (87%) received axi-cel. Twenty-two patients (69%) had a 3 month follow up imaging for assessment of response, of whom 7 patients (32%) achieved complete response (CR), 6 patients (27%) achieved partial response (PR), and 9 patients (41%) had progressive disease (PD). Persistent neutropenia was observed in 3 patients (9%), while persistent thrombocytopenia was seen in 21 cases (65%) and persistent anemia was the most common with a frequency of 72% (23/32 cases). Median time to neutrophil, platelet and Hb recoveries were 11 days (range, 5-218 days), 59.5 days (range, 4-241 days), and 76 days (range, 0-218 days), respectively. Filgrastim was used in 15 (47%) patients to facilitate neutrophil recovery. Twenty-three patients (72%) experienced neurotoxicity, of whom 11 (34%) had grade 3-4 toxicity. The frequency of CRS was 94% (29 out of 32 patients), with grade 3-4 CRS observed in 4 cases (12.5%). We observed no significant association between CRS and persistent cytopenias. In our preliminary series of 32 patients, persistent anemia and thrombocytopenia were more common than neutropenia after CAR-T cell therapy. However, most of these patients required growth factor support for neutrophil recovery. Longer duration of follow up is necessary to determine the impact of persistent cytopenias on outcomes and survival after CAR-T cell therapy.