Identification of Early Predictive Markers of Toxicity and Efficacy in Patients with DLBCL Treated with Axicabtagene Ciloleucel

Abstract

<h3>Objective</h3> CAR T cells have been extensively investigated using constructs targeting CD19+ B cells for lymphoid malignancies demonstrating efficacy (Neelapu NEJM 2018; Schuster NEJM 2018). One of the main challenges of adoptive T cell therapy are immune mediated toxicities of cytokine release syndrome (CRS) and neurotoxicity (NT). Despite impressive objective response rates, durable responses are only seen in approximately 40% of patients treated in the pivotal axicabtagene ciloleucel (axi-cel) and tisagenlecleucel trials, highlighting the need for better understanding of the mechanisms of toxicity and efficacy. We aimed to evaluate the association of early biomarkers with severe toxicity and day 90 outcomes in patients treated with commercial axi-cel in a real world setting. <h3>Methods</h3> Seventy-five patients treated with commercial axi-cel were included in this analysis. Baseline characteristics are summarized in Table 1. Patient serum samples were collected at baseline (within 30 days of conditioning chemotherapy), and then daily thereafter starting at the day of axi-cel infusion. Serum cytokine samples were analyzed using the Ella multiplex assay system. Cytokines analyzed include IL1b, IL2, IL6, IL15, TNFa, IFNg, Angiopoietin 1 and 2, as well as CRP and ferritin. Toxicities were graded daily using ASTCT consensus guidelines and retrospectively confirmed. Outcomes were evaluated at day 90 by the treating physician according to the International Working Group Response Criteria for Malignant lymphoma. P values were calculated using Wilcoxon rank sum test. <h3>Results</h3> We observed that baseline levels of CRP (p=0.0018) and Angiopoietin 2/1 ratio (p=0.0092) were associated with grade ≥3 [n=16] neurotoxicity Figure 1A-B). Baseline elevated levels of CRP (p=0.0413) and Ferritin (0.0264) were associated with more grade ≥3 CRS [n=16] (Figure 1C-D). Baseline elevated levels of CRP(p=0.0016), ferritin(p=0.0096) and IL6 (p=0.0029) were associated with poor outcomes at D90 defined as stable disease, progressive disease or death (Figure 1E-G). <h3>Conclusion</h3> We demonstrate that baseline biomarker profile can identify patients at highest risk of developing severe toxicity and/or and treatment resistance highlighting the need to validate these findings in prospective studies. Patients in this poor outcome cohort may benefit from clinical trials evaluating prophylactic agents or more combination therapies to ameliorate severe toxicities or increase response rates.