Examining the Outcomes of Watchful Waiting (WW) Among US Patients with Advanced Stage Follicular Lymphoma (FL)
Authors: Sinha Rajni , Byrtek Michelle , DeJoubner Nutan J. , Nooka Ajay K. , Taylor Michael , Cerhan James R , Friedberg Jonathan , Ziemiecki Ryan M , Hirata Jamie H. , Link Brian K , Flowers Christopher R 
Published: October 2019

Abstract
Abstract 775

Introduction:
WW has been an initial strategy for advanced stage FL because randomized trials showed no clear benefit for immediate initiation of therapy with single agent alkylators when compared to deferring therapy (Brice, JCO 1997; Ardeshna, Lancet 2003), although a recent trial raises questions about WW in the era of rituximab (R) based frontline therapies (Ardeshna, ASH Meeting 2010).

Methods:
The NLCS is a prospective, multicenter, observational study collecting data on 2,738 newly diagnosed pts with FL diagnosed from 2004–2007 at 265 US sites (80% non-academic). Initial management decisions were made by the treating physician and were categorized as WW (for pts who did not receive therapy in the 90 period following diagnoses and were coded by physicians as WW) or active therapy (AT) including: R alone, R-chemotherapy (RChemo), or other. Baseline clinical factors and treatment setting were compared for WW and AT pts using multivariable logistic regression. Kaplan-Meier (KM) estimation and Cox models were used to evaluate progression-free survival (PFS), time to 2nd and 3rd line management strategy (TT2, TT3), transformation-free survival (TFS), PFS following 1st AT, and overall survival (OS). Due to differences between WW and AT groups, adjusted Cox regression models are presented for the primary analysis of study endpoints controlling for sex, community vs. academic practice site, FL grade, and FLIPI. All time to event analyses were calculated from the 90 day period following diagnosis to allow enrollment in WW, and PFS was calculated from the starting point to the clinician's recording of progressive disease (PD) or death.

Results:
Among 1,737 pts presenting with stage III/IV FL in the analysis population, 237 underwent WW and 1,500 received AT immediately following diagnosis including: 241 pts treated with R, 1046 with RChemo, 26 with radiation, and 187 other therapies. Multivariable logistic regression demonstrated that the following pt characteristics were predictive of selection of WW rather than initial AT: age > 60 years, no B-symptoms, FL grade 1 or 2, ECOG PS = 0, ≤1 extranodal sites involved, and LDH ≤ULN (all p < 0.05). Median PFS and TT2 were 27 and 35 months for WW, and 64 months and not reached for AT. With a median follow-up of 55 months, 17% of WW pts and 19% of AT pts have died, with no significant difference in OS between WW and AT (p = 0.31). Compared with WW, RChemo improved PFS: adjusted Hazard Ratio (HR) = 0.36, TFS: HR=0.65, TT2: HR=0.48, and TT3: HR=0.53, all p<0.01. For most of the 145 WW pts that later initiated an AT, PD was recorded as the reason for treatment (83%). ATs following WW were: R (51, 35%), RCVP (21, 14%), RCHOP (16, 11%), R + other chemo (23, 16%), investigational (15, 10%), chemo alone (9, 6%), radiation (8, 6%), BMT (1, 1%), or other therapy (1, 1%). The median PFS for R was 42 months when given at diagnosis and 55 months when given following WW. The median PFS for RChemo was 71 months when given at diagnosis and 37 months when given following WW. After adjustment for FLIPI, FL grade, sex, practice setting, and type of treatment, WW adversely affected PFS following 1st AT, H=2.02, p <0.0001.

Conclusions:
FL pts in the US who undergo initial WW are treated at a median of nearly 3 years. Median PFS following RChemo, but not R is shorter when utilized after period of WW than at diagnosis – albeit in different clinical circumstances. Additional follow-up is needed to assess the tradeoff of this time without therapy with as yet no observable differences in OS.

Disclosures:
Sinha: CELGENE: Research Funding. Friedberg:Genentech: Consultancy, Membership on an entity's Board of Directors or advisory committees. Link:Genentech: Consultancy. Flowers:Spectrum: Consultancy, Research Funding; Millennium/Takeda: Consultancy, Research Funding; Celgene: Consultancy, Research Funding; Genentech/Roche (unpaid): Consultancy; Novartis: Research Funding; Seattle Genetics: Consultancy.