LONG‐TERM RESPONSES WITH LONCASTUXIMAB TESIRINE: UPDATED RESULTS FROM LOTIS‐2, THE PIVOTAL PHASE 2 STUDY IN PATIENTS WITH RELAPSED/REFRACTORY DIFFUSE LARGE B‐CELL LYMPHOMA

Introduction: Patients (pts) with diffuse large B-cell lymphoma (DLBCL) who relapse after stem cell transplant or chimeric antigen receptor therapy are refractory to second-line have poor prognosis and few treatment options (Chow et al., 2019). For these pts, long-term disease control manageable toxicity is the goal. Loncastuximab tesirine (loncastuximab tesirine-lpyl; Lonca), an anti-CD19 antibody conjugated a pyrrolobenzodiazepine dimer, demonstrated single-agent antitumor activity in LOTIS-2, pivotal phase 2 study heavily pretreated pts relapsed/refractory (R/R) DLBCL (Caimi 2021). In previously presented follow-up analyses (median follow-up: 7.8 months [mo; range: 0.3, 31.0]), durable responses Lonca were observed duration of response [mDOR]: 13.4 mo; median complete [CR]: not reached [NR]; Zinzani al. ICML, Here, we present updated efficacy safety from LOTIS-2 (NCT03589469) R/R treated Lonca, including subsets CR. Methods: was multicenter, open-label, single-arm monotherapy ≥2 prior systemic therapies. administered every 3 weeks (150 µg/kg for cycles; 75 thereafter). The primary endpoint overall rate (Lugano 2014 criteria). Secondary endpoints included DOR; CR rate; relapse-free, progression-free (PFS; measured start therapy), survival (OS). Efficacy performed all CR, event-free (no progressive death) ≥1 years (yr) cycle 1, day 1. Results: As final data cutoff (15 September 2022; mo [range: 42.6]), 70 (48%) 145 achieved 36 (25%) CR; 16 (44%) 11 (31%) yr, respectively. Median numbers doses 12.5 13.0 All yr censored at end. Among mDOR (95% CI: 6.9, -), mPFS 4.9 (2.9, 8.3), mOS 9.5 (6.7, 11.5). mDOR, mPFS, NR (Figure 1). All-grade treatment-emergent adverse events occurring ≥30% increased gamma-glutamyltransferase (42%), neutropenia (40%), thrombocytopenia (33%). Conclusions: continued demonstrate durable, profile; 31% no evidence new anticancer post-Lonca. Further needed identify factors predictive Lonca. Keywords: aggressive non-Hodgkin lymphoma, molecular targeted therapies Encore Abstract—previously submitted EHA 2023 research funded by: ADC Therapeutics SA Conflicts interests pertinent abstract P. F. Caimi Consultant advisory role: Genmab, Bristol-Myers Squibb/Celgene, Genentech, Takeda, MEI Pharma, Therapeutics, Novartis, Kite Pharma W. Z. Ai Acrotech Biopharma, BeiGene, Kymera Nurix Research funding: J. Alderuccio Genentech Honoraria: OncLive, OncInfo Other remuneration: immediate family member has served on boards of, Puma Biotechnology, Inovio Pharmaceuticals, Agios Forma Foundation Medicine K. M. Ardeshna Bristol Myers Squibb, Gilead, Novartis Hamadani AbGenomics, Celgene Corporation, Incyte Janssen R&D, Omeros, Pharmacyclics, TeneoBio, Verastem Astellas Spectrum Takeda speakers’ bureau, AstraZeneca, Sanofi Genzyme B. Hess Squibb/Celgene S. Kahl AbbVie, Celgene/BMS, TG HUTCHMED, MEI, MTEM, Kite, Epizyme, Incyte, Eli Lilly BeiGene Radford BMS, Stock ownership: AstraZeneca (spouse) speaker Seattle Genetics, Solh Partner Amgen, Genetics A. Stathis Lilly, Bayer, Roche, Oncology, Pfizer, Cellestia, Debiopharm Group, Merck/Merck Sharp & Dohme, Loxo, Philogen L. EUSA Merck Sanofi, Verastem, Sandoz bureau committee Celltrion, Janssen-Cilag, Kyowa Kirin, Servier, Y. Wang Employment leadership position: Johnson (immediate member) Qin Therapeutics. C. Xu Carlo-Stella Celgene/Bristol Karyopharm, Scenic Biotech Celgene, Gilead Sciences, Roche