Loncastuximab tesirine in relapsed/refractory diffuse large B-cell lymphoma: long-term efficacy and safety from the phase II LOTIS-2 study

Abstract

Therapies that demonstrate durable, long-term responses with manageable safety and tolerability are needed for patients with relapsed/refractory diffuse large B-cell lymphoma (R/R DLBCL). Loncastuximab tesirine (loncastuximab tesirine-lpyl [Lonca]), an anti-CD19 antibody conjugated to a potent pyrrolobenzodiazepine dimer, demonstrated single-agent antitumor activity in the pivotal phase II LOTIS-2 study in heavily pretreated patients with R/R DLBCL. Here we present updated efficacy and safety analyses from LOTIS-2, performed for all patients and in subsets of patients with a complete response (CR), including patients with CR who were event-free (no progressive disease or death) for ≥1 year and ≥2 years from cycle 1, day 1 of treatment. Lonca was administered every 3 weeks (0.15 mg/kg for 2 cycles; 0.075 mg/kg for subsequent cycles). As of the final data cutoff (September 15, 2022; median follow-up: 7.8 months [range, 0.3-42.6]), 70 of 145 (48.3%) patients achieved an overall response. Thirty-six (24.8%) patients achieved CR, of which 16 (44%) and 11 (31%) were event-free for ≥1 year and ≥2 years, respectively. In the all-treated population, the median overall survival was 9.5 months; the median progression-free survival was 4.9 months. Among patients with CR, median overall survival and progression-free survival were not reached, with 24-month overall and progression-free survival rates of 68.2% (95% CI: 50.0-81.0) and 72.5% (95% CI: 48.2-86.8), respectively. No new safety concerns were detected. With additional follow-up, Lonca continued to demonstrate durable, long-term responses with manageable safety and tolerability in patients with CR (clinicaltrials gov. Identifier: NCT03589469).

Figure 1.

Duration of response. Duration of response curve for the all-treated population (N=145) and the subsets of patients with a best response of complete response (CR) (N=36) and partial response (PR) (N=34). Reasons for censor included stem cell transplant. CI: confidence interval; NR: not reached.

Figure 2.

Kaplan–Meier curve. (A) Progression-free survival curve of the all-treated population (N=145) and the subset of patients with a best response of complete response (CR) (N=36). (B) Overall survival curve of the all-treated population and the subset of patients with a best response of CR. (C) Relapse-free survival curve of patients with a best response of CR. Reasons for censor in progression-free survival and relapse-free survival analyses included stem cell transplant. CI: confidence interval; NR: not reached.

Figure 3.

Swimmer plot of patients with complete response. Each bar represents 1 patient in the study. Response was determined by an independent review. SCT: stem cell transplant.