Long term results of a new treatment strategy for follicular low grade lymphoma (FLGL).

Abstract

e19035 Background: FLGL usually presents with widespread but asymptomatic lymphadenopathy, low SUVs on PET and normal LDH. It's considered incurable and standard of care has been 'watch and wait' (W&W) followed later by treatment if necessary. We have described a subset of patients that we termed clinically discordant indolent histology (“CDIH”) whose behavior is more aggressive. CDIH is defined as presence of any of these: B symptoms, high LDH, SUV >14 on PET, Ki-67 index >30% or involvement of areas such as lung, pleura, soft-tissue, CNS and bones. Our study aims to assess real-world long-term outcome of managing FLGL with and without CDIH. Methods: We analyzed 186 previously untreated FLGL cases treated at our center from June 2002-July 2023, without opting for W&W. CDIH cases typically received R-CHOP x6, then 4 FND. Non-CDIH mainly received FND-R. All received 2 years maintenance rituximab. Main objective was to assess 10-year PFS and OS of stage IV cases, comparing it in a real-world setting against our previously published MD Anderson (MDACC) data. Secondary objectives were to compare our 10-year PFS and OS in stage IV cases against historical controls based on the FLIPI-2 score. We also sought to determine prognostic value of CDIH as compared to FLIPI-2, evaluate early relapse rate (2 yrs), and assess rate of transformation to aggressive lymphoma. Results: Median age: 58 (26-93). Median follow up: 96 mos (6-261). Stage III-IV: 76%. CDIH was present in 56%. Our PFS 10 yrs for non-CDIH=96% vs CDIH=77% (p=0.002). For stage IV, PFS 10 yrs = 82% vs MDACC's 50% using FND-R. OS 10-yr= 90% vs MDACC's 85%. 67 pts were followed >10 years; a relapse occurred in only 5 (7%). Our PFS 10 yr for favorable FLIPI-2 (score 0)= 97%, for intermediate (1-2) =88%, unfavorable (3-5)= 72% (p=.15). Our PFS results were consistently superior to literature data across all FLIPI-2 scores. Transformation to DLBCL= 6/186 (3%) compared to 20-30% historical controls; 5 of 6 transformations were in cases with CDIH and 4 occurred within 3 yrs. Early (<2 yr) relapse rate= 2% in contrast with 20% literature data; all 4 early relapses were CDIH. Conclusions: Our findings emphasize several advantages of initiating treatment early and basing it on presence or absence of CDIH. Our data highlight the need to 1- identify CDIH for potential use of doxorubicin treatment. 2- CDIH as prognostic factor seems more effective than FLIPI-2. 3- PFS 10 yr results are remarkably superior to both literature controls and to our previous experience at MDACC with FND-R. 4- Only 7% relapses beyond 10 yrs suggest potential for cure, according to our results and those from MDACC. [Table: see text]