CELESTIMO: A phase III trial evaluating the efficacy and safety of mosunetuzumab plus lenalidomide versus rituximab plus lenalidomide in patients with relapsed or refractory follicular lymphoma who have received ≥ 1 line of systemic therapy.

Abstract

TPS7588 Background: Despite significant progress with first-line immunochemotherapy, most patients with follicular lymphoma (FL) will eventually relapse with increasing refractoriness and decreasing duration of response to subsequent therapy lines (Rivas-Delgado et al. 2019). Mosunetuzumab (M) is a CD20xCD3 bispecific antibody that engages and redirects T-cells to eliminate malignant B cells (Sun et al. 2015). In an ongoing, pivotal Phase I/II trial of M monotherapy, patients with relapsed/refractory (R/R) FL who have received ≥2 prior treatment lines achieve deep and durable responses (NCT02500407; Budde et al. ASH 2021). Preliminary data from a Phase Ib study have suggested favorable safety and promising activity of M in combination with lenalidomide (Len), a potent immunomodulatory agent that has shown additive/synergistic activity with an anti-CD20 antibody in R/R indolent lymphoma (Leonard et al. 2019), in patients with R/R FL who have received ≥1 prior therapy (NCT04246086; Morschhauser et al. ASH 2021). The chemotherapy-free M-Len combination may represent a promising outpatient therapy option for future management of patients with R/R FL. The randomized, multicenter Phase III study has been initiated. Methods: CELESTIMO (NCT04712097) is a randomized, multicenter, open-label Phase III study evaluating the efficacy and safety of M-Len versus rituximab plus Len (R-Len) in patients with previously treated R/R FL. Patients must have histologically documented CD20+ FL (Grades 1–3a) requiring systemic therapy and have received ≥1 prior line of systemic therapy. Patients are randomized (1:1) to receive M-Len (M intravenously [IV] on Days [D] 1, 8 and 15 of Cycle [C] 1 [21-day cycle] and D1 of C2–12 [28-day cycles], plus Len orally [PO] on D1–21 of C2–12) or R-Len (R IV on D1, 8, 15 and 22 of C1 then on D1 of C3, 5, 7, 9, and 11, plus Len PO on D1–21 of C1–12 [all 28-day cycles]), and stratified by disease progression within 24 months of initial treatment (yes/no), number of prior lines of therapy (1 versus ≥2), and refractoriness to anti-CD20 therapy (refractory/non-refractory). The primary endpoint is progression-free survival (PFS) assessed by independent review committee; secondary endpoints include investigator-assessed PFS, complete and objective response, overall survival, and safety. Biomarkers predictive of response to M-Len and R-Len will also be investigated as exploratory endpoints. The study started recruitment in 2021 and plans to enroll ̃400 patients from approximately 16 countries and 150 sites globally. Clinical trial information: NCT04712097.