Zamtocabtagene autoleucel in relapsed/refractory B-NHL: 5-year follow-up of a CD20/19 tandem CAR T-cell phase 1 trial

ABSTRACT: Emerging long-term data indicate relapse rates of >50% after CD19-redirected chimeric antigen receptor (CAR) T-cell therapy in relapsed or refractory (R/R) B-cell non-Hodgkin lymphoma (B-NHL). To reduce selective pressure on the CD19 antigen, we conducted a first-in-human phase 1 clinical trial of zamtocabtagene autoleucel (zamto-cel), a noncryopreserved tandem CD20-CD19-directed CAR T-cell therapy. Two predefined dose levels (dose level 1 [DL1], 1 × 106 and DL2, 2.5 × 106 CAR+ T cells per kg bodyweight) were applied. The primary end point (EP) was the maximum tolerated dose (MTD). Secondary EPs included adverse events, best overall response (BOR), and biomarker assessments. A total of 12 patients, 6 patients per DL, were treated. No dose-limiting toxicity and no cytokine release syndrome or immune effector cell-associated neurotoxicity syndrome of grade ≥3 were observed. Thus, MTD was not reached. The BOR by investigator assessment was 75%, with 5 of 12 patients (42%) achieving complete remission (CR) until month 12 with no relapse in clinical evaluation up to 5 years after infusion. CR was associated with a higher mean maximum observed concentration of zamto-cel and detection of zamto-cel beyond month 6. Additional product characterization revealed increased expression of CD27 and CD127 along with increased expansion of CAR+ central memory T cells in patients with CR, facilitating persistence and improved outcomes in R/R B-NHL treated with zamto-cel. Based on the promising risk-to-benefit ratio, evaluation of zamto-cel at DL2 is ongoing in pivotal phase 2 clinical trials for patients with R/R aggressive B-NHL. This trial was registered at www.ClinicalTrials.gov as NCT03870945.