Glofitamab monotherapy retreatment in patients with heavily pre-treated relapsed or refractory (R/R) non-Hodgkin lymphoma (NHL): Results from a phase I/II study.
Authors: Bartlett Nancy L. , Dickinson Michael , Hutchings Martin , Carlo-Stella Carmelo , Wu Shang-Ju , Leppä Sirpa , Trneny Marek , Corradini Paolo , Offner Fritz , Mulvihill Estefania , Bottos Alessia , Chohan Saibah , Baumlin Pauline , Relf James , Lundberg Linda , Bachy Emmanuel 
Published: June 2024

7020 Background: Fixed-duration glofitamab, a CD20xCD3 T-cell engaging bispecific antibody with a novel 2:1 configuration, has demonstrated efficacy and manageable safety in a Phase I/II study (NCT03075696) in heavily pre-treated patients (pts) with R/R NHL (Dickinson. N Engl J Med 2022). We report efficacy and safety data for pts with R/R NHL retreated with glofitamab monotherapy after response to initial glofitamab treatment. Methods: Pts who completed initial treatment and achieved complete response (CR), partial response (PR), or stable disease were eligible for retreatment after documented progression. Initial treatment included obinutuzumab pre-treatment (Gpt) 7 days before the first glofitamab dose, then glofitamab intravenously at either a fixed dose of 0.015–25mg (14- or 21-day cycles) or step-up dosing (2.5mg, then 10mg in Cycle [C] 1, followed by a target dose of 16 or 30mg [C2 onward, 21- day cycles]) for up to 12 cycles. Retreatment was administered at the escalation dose received or at the highest glofitamab dose cleared in the study at time of retreatment, with Gpt 7 days before the first glofitamab dose. As with initial treatment, retreatment was permitted for 12 cycles or until progression or unacceptable toxicity, whichever occurred first. Results: As of Sept 4, 2023, 13 pts (diffuse large B-cell lymphoma [DLBCL], n=4; follicular lymphoma [FL], n=4; mantle cell lymphoma [MCL], n=2; transformed FL [trFL], n=2; high grade B-cell lymphoma, n=1) had received glofitamab retreatment (retreatment dose: 10mg, n=1; 10/16mg, n=1; 2.5/10/30mg, n=11). Median age was 63.0 years (range: 44–81). With initial treatment, 9 pts had CR and 4 pts had PR (best response by investigator). Median time from end of initial treatment to initiation of retreatment was 13.0 months (range: 4.1–27.4). Median number of retreatment cycles received was 5 (range: 2–12). During retreatment, 9 pts (69.2%) responded: CR, 38.5% (FL, n=2; trFL, n=1; MCL, n=2); PR, 30.8% (FL, n=1; trFL, n=1; DLBCL, n=2). Of the 5 pts with CR at retreatment, 3 pts had CR and 2 pts had PR with initial treatment. Of the 4 pts with PR at retreatment, 3 pts had CR and 1 pt had PR with initial treatment. Median retreatment follow-up time was 25.9 months and 5 pts had responses ongoing at data cut-off (FL, n=2; MCL, n=2; trFL, n=1). The safety profile for glofitamab retreatment was consistent with prior reports of glofitamab monotherapy in R/R NHL (Hutchings. J Clin Oncol 2021). Cytokine release syndrome occurred in 7 pts (53.8%; all Grade 1/2). Exploratory data on B-cell pharmacodynamics, CD20 expression, and T-cell status before retreatment will be presented. Conclusions: Glofitamab monotherapy retreatment was efficacious in heavily pre-treated pts with R/R NHL who responded to initial glofitamab treatment before subsequent progression. The safety profile was consistent with that of initial treatment. Clinical trial information: NCT03075696 .