Ibrutinib-based therapy reinvigorates CD8 T cells compared to chemoimmunotherapy: immune-monitoring from the E1912 trial

Bruton's tyrosine kinase Inhibitors (BTKis) that target B cell receptor signaling have led to a paradigm shift in CLL treatment. BTKis have been shown to reduce abnormally high CLL-associated T cell counts and the expression of immune checkpoint receptors concomitantly with tumor reduction. However, the impact of BTKi therapy on T cell function has not been fully characterized. Here, we performed longitudinal immunophenotypic and functional analysis of pre- and on-treatment (6- and 12-months) peripheral blood samples from patients in the phase 3 E1912 trial comparing ibrutinib-rituximab to fludarabine, cyclophosphamide and rituximab (FCR). Intriguingly, we report that despite reduced overall T cell counts, higher numbers of T cells including effector CD8+ subsets at baseline and at the 6-month time-point associated with no infections and favorable progression-free survival (PFS) in the ibrutinib-rituximab arm. Assays demonstrated enhanced anti-CLL T cell killing function during ibrutinib-rituximab, including a switch from predominantly CD4+ T-cell:CLL immune synapses at baseline to increased CD8+ lytic synapses on-therapy. Conversely, in the FCR arm, higher T cell numbers correlated with adverse clinical responses and showed no functional improvement. We further demonstrate the potential of exploiting rejuvenated T cell cytotoxicity during ibrutinib-rituximab using the bispecific antibody glofitamab - supporting combination immunotherapy approaches

Measurable residual disease does not preclude prolonged progression-free survival in CLL treated with ibrutinib

E1912 was a randomized phase 3 trial comparing indefinite ibrutinib plus six cycles of rituximab (IR) to six cycles of fludarabine, cyclophosphamide and rituximab (FCR) in untreated younger patients with CLL. We describe measurable residual disease (MRD) levels in E1912 over time and correlate them with clinical outcome. Undetectable MRD rates (\u3c 1 CLL cell per 104 leukocytes) were 29.1%, 30.3%, 23.4% and 8.6% at 3, 12, 24 and 36 months for FCR, and significantly lower at 7.9%, 4.2% and 3.7% at 12, 24 and 36 months for IR, respectively. Undetectable MRD at 3, 12, 24 and 36 months was associated with longer progression-free survival (PFS) for the FCR arm with hazard ratios (MRD detectable / MRD undetectable) of 4.29 (95% CI 1.89 - 9.71), 3.91 (95% CI 1.39 - 11.03), 14.12 (95% CI 1.78 - 111.73), and not estimable (no events among those with undetectable MRD), respectively. For the IR arm, patients with detectable MRD did not have significantly worse PFS compared to those in whom MRD was undetectable; however, PFS was longer for those with MRD levels of less than 10-1 compared to those with MRD levels above this threshold. Our observations provide additional support for the use of MRD as a surrogate endpoint for PFS in patients receiving FCR. For patients on indefinite ibrutinib-based therapy, PFS did not differ significantly by undetectable MRD status, while those with MRD less than 10-1 tend to have longer PFS, although continuation of ibrutinib is very likely required to maintain treatment efficacy

Preneoplastic Alterations Define CLL DNA Methylome and Persist through Disease Progression and Therapy

Most human cancers converge to a deregulated methylome with reduced global levels and elevated methylation at select CpG islands. To investigate the emergence and dynamics of the cancer methylome, we characterized genome-wide DNA methylation in pre-neoplastic monoclonal B cell lymphocytosis (MBL) and chronic lymphocytic leukemia (CLL), including serial samples collected across disease course. We detected the aberrant tumor-associated methylation landscape at CLL diagnosis and found no significantly differentially methylated regions in the high-count MBL-to-CLL transition. Patient methylomes showed remarkable stability with natural disease and post-therapy progression. Single CLL cells were consistently aberrantly methylated, indicating a homogeneous transition to the altered epigenetic state, and a distinct expression profile together with MBL cells compared to normal B cells. Our longitudinal analysis reveals the cancer methylome to emerge early, which may provide a platform for subsequent genetically-driven growth dynamics and together with its persistent presence suggests a central role in the normal-to-cancer transition

Polygenic risk score and risk of monoclonal B-cell lymphocytosis in caucasians and risk of chronic lymphocytic leukemia (CLL) in African Americans

Monoclonal B-cell lymphocytosis (MBL) is a precursor to CLL. Other than age, sex, and CLL family-history, little is known about factors associated with MBL risk. A polygenic-risk-score (PRS) of 41 CLL-susceptibility variants has been found to be associated with CLL risk among individuals of European-ancestry(EA). Here, we evaluate these variants, the PRS, and environmental factors for MBL risk. We also evaluate these variants and the CLL-PRS among African-American (AA) and EA-CLL cases and controls. Our study included 560 EA MBLs, 869 CLLs (696 EA/173 AA), and 2866 controls (2631 EA/235 AA). We used logistic regression, adjusting for age and sex, to estimate odds ratios (OR) and 95% confidence intervals within each race. We found significant associations with MBL risk among 21 of 41 variants and with the CLL-PRS (OR = 1.86, P = 1.9 × 10-29, c-statistic = 0.72). Little evidence of any association between MBL risk and environmental factors was observed. We observed significant associations of the CLL-PRS with EA-CLL risk (OR = 2.53, P = 4.0 × 10-63, c-statistic = 0.77) and AA-CLL risk (OR = 1.76, P = 5.1 × 10-5, c-statistic = 0.62). Inherited genetic factors and not environmental are associated with MBL risk. In particular, the CLL-PRS is a strong predictor for both risk of MBL and EA-CLL, but less so for AA-CLL supporting the need for further work in this population