A phase 2 study of axicabtagene ciloleucel in relapsed or refractory large B-cell lymphoma in Japan: 1-year follow-up and biomarker analysis

Axicabtagene ciloleucel (axi-cel) is an autologous, CD19-targeting chimeric antigen receptor T‑cell therapy. We recently reported the 3-month follow-up results of a phase 2, multicenter, open‑label, single-arm study of axi-cel in Japanese patients with relapsed or refractory (R/R) large B-cell lymphoma (LBCL) (JapicCTI-183914). Here, we present 1-year efficacy and safety data and biomarker analysis data regarding mechanisms of resistance to axi-cel. Primary and secondary endpoints included investigator-assessed objective response rate (ORR), serious adverse events, and treatment-emergent adverse events. Axi-cel pharmacokinetics were also examined. Biomarker analysis was performed by cytokine measurement, immunohistochemistry, RNA sequencing, and whole-exome sequencing. At a median follow-up of 13.4 months, ORR was 86.7% (13/15 patients), and the complete response (CR) rate improved to 53.3% (8/15 patients) due to response conversion. Seven patients experienced disease progression, and one achieved CR after re-treatment with axi-cel. No new safety concerns were detected. Plausible resistance mechanisms to axi-cel varied among patients but included CD19 downregulation, programmed death-ligand 1 upregulation, and increased macrophage and angiogenesis signatures. The 1-year efficacy and safety of axi-cel were confirmed in Japanese patients with R/R LBCL. Resistance to treatment may involve multiple factors, including target antigen loss and an unfavorable tumor environment. Clinical trial registration: Japan Clinical Trials Information; JapicCTI-183914.