Loncastuximab tesirine in Chinese patients with relapsed or refractory diffuse large B-cell lymphoma: a multicenter, open-label, single-arm, phase II trial.

Patients with relapsed or refractory (R/R) diffuse large B-cell lymphoma (DLBCL) have a poor prognosis. Loncastuximab tesirine (Lonca), an antibody conjugate targeting CD19, has demonstrated significant clinical benefit in R/R DLBCL in a global phase II LOTIS-2 study. In the China bridging pivotal phase II OL-ADCT-402-001 study, eligible patients aged ≥18 years with R/R DLBCL who had failed ≥2 lines of systemic therapies were enrolled and treated every 3 weeks with 150 μg/kg Lonca for two cycles; then 75 μg/kg for subsequent cycles (up to 1 year). The primary endpoint was overall response rate (ORR) assessed by an independent review committee. Primary analyses for efficacy and safety were performed on the patients who received at least one treatment and had at least 6 months of follow-up following an initial documented response. As of data cutoff, 64 patients received Lonca (median 4.0 cycles; range, 1-17). The median number of prior lines of therapies was 3.0 (range, 2-12). The ORR was 51.6% (95% confidence interval [CI]: 38.7-64.2), and the complete response rate was 23.4%. Hematological events accounted for the majority of the most common (≥15%) grade ≥3 treatment-emergent adverse events (TEAE), in which increased γ-glutamyltransferase (25.0%), and hypokalaemia (18.8%) also were reported. Serious TEAE were reported in 35 of 64 patients with four fatal TEAE. In conclusion, Lonca monotherapy demonstrated clinically meaningful efficacy and was well-tolerated in heavily pretreated Chinese patients with R/R DLBCL, which was consistent with the results of the LOTIS-2 study in Caucasian patients.