CLL-217 Patient Characteristics and Time to Next Treatment With Ibrutinib and Anti-CD20 Monotherapy as First-Line Treatment in Patients With Chronic Lymphocytic Leukemia/Small Lymphocytic Lymphoma

Context: While ibrutinib has been established as a preferred first-line (1L) treatment for chronic lymphocytic leukemia (CLL)/small lymphocytic lymphoma (SLL), anti-CD20 monotherapy (rituximab or obinutuzumab) is sometimes prescribed as symptomatic or palliative therapy. Objective: To describe and compare patient characteristics and outcomes between ibrutinib and anti-CD20 monotherapy for CLL/SLL patients who initiated a 1L of therapy in community oncology practice. Design: The nationwide electronic health record-derived deidentified database (03/04/2016-09/30/2021) was used to collect medical encounter and prescription data. Patient baseline characteristics before 1L treatment were compared between the two groups. Propensity score-based inverse probability of treatment weighting (IPTW) was used to adjust for baseline differences between groups. Kaplan-Meier (KM) analysis was used to evaluate time to next treatment (TTNT) from 1L initiation. Two subgroup analyses were performed among patients with high-risk cytogenetic markers (del17p, del11q, unmutated IGHV) and those without IGHV testing. Results: Of the 3,226 patients identified, 2,188 (67.8%) received 1L ibrutinib and 1,038 (32.2%) received a 1L anti-CD20 monotherapy. The average age was 71.4 years for ibrutinib users and 72.9 years for anti-CD20 users. Female patients were 39% of those prescribed ibrutinib and 42% of those given anti-CD20. Patients treated with ibrutinib were more likely to have high-risk cytogenetic markers (42.6% vs 27.9%). The median TTNT was not reached in ibrutinib-treated patients and 18.3 months in anti-CD20-treated patients. The hazard ratio was 0.30 (95% CI: 0.27-0.34, p<0.001) in favor of ibrutinib. In the subgroup with high-risk genetic markers, the hazard ratio was 0.26 (0.21-0.33, p<0.001). In the subgroup without IGHV testing, the hazard ratio was 0.30 (0.26-0.36, p<0.001). Conclusions: A substantial number of CLL/SLL patients received 1L treatment with anti-CD20 monotherapy in community oncology practice. The outcomes showed that ibrutinib resulted in a significantly longer duration before starting a second-line treatment compared with anti-CD20 monotherapy. This advantage was consistently demonstrated in patients with high cytogenetic risk features and without IGHV testing.