Multicenter phase 2 trial of atezolizumab plus obinutuzumab and PET-adapted nodal radiotherapy for treatment-naïve follicular lymphoma

Standard first-line chemoimmunotherapy for follicular lymphoma (FL) yields high efficacy but serious toxicity in 65% of patients. The multicenter phase 2 FLUORO trial in Australia evaluated 6 cycles of atezolizumab and obinutuzumab with PET-adapted ultra-low-dose radiotherapy (RT; 4Gy) to all PET-avid sites after cycle 2, followed by 2 years of obinutuzumab maintenance, in high tumor burden treatment-naïve FL. Sixteen patients were enrolled (median age 53 years; 94% intermediate-high FLIPI score). The primary endpoint of complete respons was achieve in 93% (95% CI 70-99) with objective response rate 100% (75-100). With a median follow-up of 41 months, the median progression-free survival and overall survival were not reached, with 3-year rates of 80% and 100%, respectively. Grade 3 or 4 adverse events occurred in 31% of patients. The authors conclude that the novel multimodality combination of atezolizumab, obinutuzumab, and low-dose RT demonstrated promising efficacy and safety in treatment-naïve FL.