Canadian evidence-based guideline for frontline treatment of chronic lymphocytic leukemia: 2022 update

Treatment of Chronic Lymphocytic Leukemia in the Personalized Medicine Era

Chronic lymphocytic leukemia is a lymphoproliferative disorder marked by the expansion of monoclonal, mature CD5+CD23+ B cells in peripheral blood, secondary lymphoid tissues, and bone marrow. The disease exhibits significant heterogeneity, with numerous somatic genetic alterations identified in the neoplastic clone, notably mutated TP53 and immunoglobulin heavy chain mutational statuses. Recent studies emphasize the pivotal roles of genetics and patient fragility in treatment decisions. This complexity underscores the need for a personalized approach, tailoring interventions to individual genetic profiles for heightened efficacy. The era of personalized treatment in CLL signifies a transformative shift, holding the potential for improved outcomes in the conquest of this intricate hematologic disorder. This review plays a role in elucidating the evolving CLL treatment landscape, encompassing all reported genetic factors. Through a comprehensive historical analysis, it provides insights into the evolution of CLL management. Beyond its retrospective nature, this review could be a valuable resource for clinicians, researchers, and stakeholders, offering a window into the latest advancements. In essence, it serves as a dynamic exploration of our current position and the promising prospects on the horizon.

Canadian evidence-based guideline for treatment of relapsed/refractory chronic lymphocytic leukemia

Following the recent publication of Canadian evidence-based guidelines for frontline treatment of chronic lymphocytic leukemia (CLL), the same group of clinicians developed guidelines for CLL in the relapsed/refractory (R/R) setting. The treatment of R/R CLL has changed significantly in the past few years, with many novel therapeutics available to hematologists across the country. These guidelines aim to standardize the management of CLL in the relapsed/refractory setting, using the best evidence currently available.

Clinical Outcomes in a Large Canadian Centralized CLL Clinic Based on Treatment and Molecular Factors over a Decade

FISH cytogenetics, TP53 sequencing, and IGHV mutational status are increasingly used as prognostic and predictive markers in chronic lymphocytic leukemia (CLL), particularly as components of the CLL International Prognostic Index (CLL-IPI) and in directing therapy with novel agents. However, testing outside of clinical trials is not routinely available in Canada. As a centralized CLL clinic at CancerCare Manitoba, we are the first Canadian province to evaluate clinical outcomes and survivorship over a long period of time, incorporating the impact of molecular testing and the CLL-IPI score. We performed a retrospective analysis on 1315 patients diagnosed between 1960 and 2018, followed over a 12-year period, where 411 patients had molecular testing and 233 patients had a known CLL-IPI score at the time of treatment. Overall, 40.3% (n = 530) of patients received treatment, and 47.5% (n = 252) of patients received multiple lines of therapy. High-risk FISH and CLL-IPI (4-10) were associated with higher mortality (HR 2.03, p = 0.001; HR 2.64, p = 0.002), consistent with other studies. Over time, there was an increase in the use of targeted agents in treated patients. The use of Bruton's tyrosine kinase inhibitors improved survival in patients with unmutated IGHV and/or TP53 aberrations (HR 2.20, p = 0.001). The major cause of death in patients who received treatment was treatment/disease-related (32%, n = 42) and secondary malignancies (57%, n = 53) in those who were treatment-naïve. Our data demonstrate the importance of molecular testing in determining survivorship in CLL and underpinning the likely immune differences in outcomes for those treated for CLL.

A Non-Canonical Role for the Glycosyltransferase Enzyme UGT2B17 as a Novel Constituent of the B Cell Receptor Signalosome

In chronic lymphocytic leukemia (CLL), an elevated glycosyltransferase UGT2B17 expression (UGT2B17^HI) identifies a subgroup of patients with shorter survival and poor drug response. We uncovered a mechanism, possibly independent of its enzymatic function, characterized by an enhanced expression and signaling of the proximal effectors of the pro-survival B cell receptor (BCR) pathway and elevated Bruton tyrosine kinase (BTK) phosphorylation in B-CLL cells from UGT2B17^HI patients. A prominent feature of B-CLL cells is the strong correlation of UGT2B17 expression with the adverse marker ZAP70 encoding a tyrosine kinase that promotes B-CLL cell survival. Their combined high expression levels in the treatment of naïve patients further defined a prognostic group with the highest risk of poor survival. In leukemic cells, UGT2B17 knockout and repression of ZAP70 reduced proliferation, suggesting that the function of UGT2B17 might involve ZAP70. Mechanistically, UGT2B17 interacted with several kinases of the BCR pathway, including ZAP70, SYK, and BTK, revealing a potential therapeutic vulnerability. The dual SYK and JAK/STAT6 inhibitor cerdulatinib most effectively compromised the proliferative advantage conferred by UGT2B17 compared to the selective BTK inhibitor ibrutinib. Findings point to an oncogenic role for UGT2B17 as a novel constituent of BCR signalosome also connected with microenvironmental signaling.

Population-level impact of ibrutinib for chronic lymphocytic leukemia in British Columbia, Canada

Ibrutinib has dramatically changed the treatment landscape for chronic lymphocytic leukemia (CLL) since its availability in British Columbia (BC), Canada in 2014. We analyzed patterns of use and real-world survival outcomes in 370 patients who received ibrutinib for first-line (1 L, n = 35) and relapsed/refractory (R/R, n = 335) CLL between 2014-2018 in BC. Dose reductions and interruptions were frequent in 32% and 27%, respectively. With a median follow-up of 27.6 months, 35% of patients discontinued ibrutinib, primarily for adverse events (AEs) rather than progressive disease. Over the course of treatment, 87% of patients experienced at least one adverse event. The 2-year overall survival (OS) and event-free survival (EFS) were excellent at 83.9% and 76.1%, respectively, with medians not reached. However, patients who discontinued ibrutinib had a median OS of 32.5 months and median EFS of only 3.8 months from time of discontinuation, highlighting the need to minimize toxicity in the real-world.