Impact of Individual Comorbidities on Treatment Outcomes in Chronic Lymphocytic Leukemia

• Published in: Blood 2018-11, Vol.132 (Supplement 1), p.4848-4848
• Main Authors: Gordon, Max J., Churnetski, Michael C, Alqahtani, Hamood, Rivera, Xavier Issac, Kittai, Adam, Bruss, Nur, Hoff, Sheila, Choi, Michael Y., Cohen, Jonathon B., Persky, Daniel, Park, Byung, Danilov, Alexey V
• Format: Article
• Language: English
• ISSN: 0006-4971; 1528-0020
• DOI: 10.1182/blood-2018-99-113917

Introduction: Chronic lymphocytic leukemia (CLL) is a common leukemia which tends to occur late in life. Comorbidities are common, and the iwCLL guidelines recommend their assessment in patients (pts) enrolled on clinical trials. The Cumulative Illness Rating Scale (CIRS) is a rigorous tool designed to evaluate the burden of comorbidities, which has been employed in therapeutic studies. Our group and others demonstrated that CIRS score predicts survival in pts with CLL treated with either chemo-immunotherapy (CIT) or novel kinase inhibitors (KI; ibrutinib) (Manda et al, 2016 & Gordon et al, 2018). However, CIRS has not become part of common clinical practice, in part due to complexities in scoring. It is also unknown whether all of the 14 organ systems included in the score carry equal weight to determine prognosis. Here we report the impact of specific comorbidities from a multicenter retrospective cohort of CLL pts treated with either CIT or KI. Methods: We conducted a retrospective analysis of pts with CLL treated at five US academic medical centers between 2000 and 2017. CIRS score was calculated as in Salvi et al, 2008. Random forest (RF) was used to assess specific comorbidities' impact on overall survival (OS) and event-free survival (EFS, defined as time to new therapy, disease progression or death). We adapted two separate approaches to investigate the RF variable selection process: variable Importance (VIMP), a property related to variable misspecification, and Minimal Depth (MD), a property derived from the construction of trees within the forest. Best variables were those selected consistently as top 3 in both VIMP and MD on the 500 RF repetitions. Because hepatic and renal comorbidities were rare they were excluded. OS and EFS were assessed by Kaplan-Meier estimates and Cox proportional hazard model adjusted for performance status and age. Significance was assessed with log-rank test. Results: 398 pts were included in the final analysis. The median age was 63 years (range, 30-93). 50% of pts (n=198) had a high CIRS score (≥7). 184 pts (46%) had comorbidities assessed in relapsed setting. For all pts, the most common treatments included ibrutinib (n=145; 37%), fludarabine-containing regimens (n=104; 26%) and bendamustine (n=39; 10%). Complex karyotype was observed in 3.5% (n=14) and 10.6% (n=42) of pts had del(17p). Pts with comorbidities (CIRS ≥7) demonstrated shortened survival following therapy, with 5-year OS of 64% vs 89% (p