Patterns and Outcomes of Infused Therapy for Chronic Lymphocytic Leukemia (CLL) in a Medicare Population.
Authors: Griffiths Robert , Reyes Carolina , Gleeson Michelle , Knopf Kevin , Danese Mark 
Published: October 2019

Abstract
Abstract 4409

Introduction
Initial treatment for CLL can include observation only or treatment with one or more drugs, depending on stage at diagnosis and risk category. Little is known about the use and outcomes of infused therapy for CLL in routine clinical practice in the Medicare population (age≥65).

Objectives
The objectives were to identify patterns and outcomes of initial infused therapy, in routine clinical practice, in a cohort of Medicare patients diagnosed with CLL.

Patients and Methods
The source of data was the Surveillance, Epidemiology, and End Results (SEER) database linked to Medicare claims. Patients were included if they were diagnosed with CLL between January 1, 1999 and December 31, 2005, enrolled in Medicare parts A and B, and had at least one year of Medicare coverage prior to CLL diagnosis to allow calculation of an NCI Comorbidity Index score at baseline. They were followed until December 31, 2006 or death, whichever came first. Intravenous agents used as part of initial infused therapy, including chemotherapy and immunotherapy (rituximab), were identified through Medicare claims. Cox proportional hazards models were used to identify factors associated with receiving infused therapy, and factors associated with improved survival among those receiving infused therapy. Separate survival analyses were performed for those who began initial infused therapy within, versus after, 180 days of CLL diagnosis.

Results
There were 6,645 patients who met the study inclusion criteria. The average (and median) age at diagnosis was 77 years; 55% were male gender; 88% were white race; and 37% had an NCI Comorbidity Index ≥ 1. During the study period, infused therapy was provided to 2,335 (35%) patients, and the median time to initial treatment was 41 weeks (mean 73 weeks). As initial infused therapy, 1,046/2,335 (45%) received rituximab with or without chemotherapy; and 1,289 (55%) received chemotherapy alone. The most common chemotherapy agents were fludarabine (42%) and vincristine (11%). There was no difference in the mean time to initial treatment between those who received and those who did not receive rituximab (74 and 72 weeks respectively: p=0.62). In multivariate analysis of factors associated with time to initial infused therapy, age ≥ 80 (compared to 66-69) was associated with a significantly longer time to treatment (HR:0.78; p<0.001), while male gender (HR:1.27; p<0.001), Hispanic race/ethnicity (compared to white: HR:1.27; p=0.05), and later year of CLL diagnosis all were associated with shorter time to treatment. Adjusting for patient demographic and clinical characteristics, in the group of patients who began initial infused therapy after 180 days following diagnosis (n=1,253), therapy that included rituximab was associated with a statistically significantly lower mortality rate (HR: 0.73; p<0.01) compared to chemotherapy alone. This was also the case for patients treated in the first 180 days after diagnosis, where infused therapy including rituximab was associated with a 29% lower mortality rate than chemotherapy alone (p<0.001).

In a large cohort of Medicare patients diagnosed with CLL, who were followed for up to 8 years, approximately one third received infused therapy. Among those who received infused therapy, use of rituximab with or without chemotherapy was associated with lower mortality than chemotherapy alone.

Disclosures:
Griffiths: Genentech Inc: Consultancy. Off Label Use: Rituximab. Reyes:Genentech Inc: Employment. Gleeson:Genentech Inc: Consultancy. Knopf:Genentech Inc: Consultancy. Danese:Genentech Inc: Consultancy.