GO29781 phase I/II subgroup analysis: Mosunetuzumab in older patients with R/R B-NHL

Results from a post hoc subgroup analysis of the phase I/II GO29781 study (NCT02500407), evaluating mosunetuzumab in patients with relapsed/refractory (R/R) B-cell non-Hodgkin lymphoma (B-NHL), were published in the British Journal of Haematology by Thiruvengadam et al. The primary objective of this analysis was to assess the safety of mosunetuzumab in older patients (aged ≥65 years) from the overall R/R B-NHL cohort (N = 102) and the R/R follicular lymphoma (FL) cohort (n = 30). Key secondary endpoints included progression-free survival (PFS), overall survival (OS), duration of response (DoR), and time-to-next treatment (TTNT) or death in older vs younger (aged <65 years) patients with R/R FL.

Key data: In the overall R/R B-NHL cohort, treatment-related adverse events (TRAEs) of any grade were reported in 84.3% of older patients vs 87.9% of younger patients (FL cohort, 90% vs 93.3%). Grade ≥3 TRAEs were reported in 46.1% vs 48.3% of older patients vs younger patients in the R/R B-NHL cohort (FL cohort, 53.3% vs 50.0%). The most common adverse events (AEs) of any grade in older vs younger patients with R/R B-NHL were cytokine release syndrome (CRS; 33.3% vs 44.8%), fatigue (38.2% vs 26.7%), pyrexia (19.6% vs 28.4%), hypophosphatemia (21.6% vs 23.3%), headache (17.6% vs 22.4%), and nausea (13.7% vs 20.7%). Serious AEs (SAEs) were similar between older and younger patients with R/R NHL (45.1% vs 46.6%), while serious infections were more common in older patients (46.5% vs 16.4%). In patients with R/R FL, overall response rate (ORR; 86.7% vs 76.7%), complete response rate (CRR; 70.0% vs 55.0%), PFS (17.9 months vs 12.0 months), and TTNT (not reached [NR] vs 18.1 months) were numerically higher in older vs younger patients.

Key learning: Mosunetuzumab demonstrated comparable safety in older vs younger patients with R/R B-NHL and efficacy in older patients with R/R FL, supporting its use across age groups. Additional studies are warranted to evaluate safety and efficacy of mosunetuzumab in older patients with R/R B-NHL, and to identify factors associated with response.