Outcomes of <scp>CD19 CAR</scp> T in Transformed Indolent Lymphoma Compared to De Novo Aggressive Large B‐Cell Lymphoma

Chimeric antigen receptor (CAR) T-cell therapy has revolutionized treatment of aggressive large B-cell lymphoma (aLBCL). Patients with transformed indolent non-Hodgkin lymphoma (tiNHL) were included in key CAR trials, but outcomes of CAR for this distinct, historically high-risk group are poorly understood. We conducted a multicenter retrospective study of 1182 patients with aLBCL receiving standard-of-care CAR T between 2017 and 2022, including 338 (29%) with tiNHL. Rates of grade ≥ 3 cytokine release syndrome (CRS) were similar between tiNHL and de novo cohorts (7% vs. 8%, p = 0.6), while grade ≥ 3 immune effector cell-associated neurotoxicity syndrome was lower in tiNHL (21% vs. 27%, p = 0.02). Overall response rate was similar in both cohorts (83% vs. 81%, p = 0.3), while complete response rate was higher in tiNHL (67% vs. 59%, p = 0.017). With a median follow-up of 22.3 months, the progression/relapse-free (PFS) and overall survival (OS) were similar between the tiNHL and de novo cohorts (24-month PFS 41% [95% CI: 35%-46%] vs. 38% [95% CI: 35%-42%]; 24-month OS 58% [95% CI: 52%-63%] vs. 52% [95% CI: 48%-56%], respectively). After adjusting for key risk factors, there was a trend toward a lower hazard of disease progression, relapse or death post-CAR for tiNHL patients compared to de novo aLBCL patients (HR: 0.84 [95% CI: 0.69-1.0], p = 0.07). Elevated LDH, advanced stage, prior bendamustine within 12 months of CAR, receipt of bridging therapy, CNS involvement, and ≥ 3 prior lines of therapy were each associated with inferior PFS. In conclusion, CAR T therapy is highly effective with an acceptable toxicity profile in patients with tiNHL.