Predictors of response and survival in a large cohort of 319 Waldenström macroglobulinemia patients treated with ibrutinib monotherapy

Bruton tyrosine kinase (BTK) inhibitors are the only FDA-approved treatments for Waldenström macroglobulinemia (WM). Factors prognostic of survival and predictive of response to BTK inhibitors remained to be clarified. We evaluated 319 patients with WM to identify predictive and prognostic factors on ibrutinib monotherapy. Logistic and Cox proportional-hazard regression models were fitted for response and survival. Multiple imputation analyses were used to address bias associated with missing data. Major (partial response or better) and deep responses (very good partial response or better) were attained in 78% and 28% of patients. CXCR4 mutations were associated with lower odds of major (OR 0.2, 95% CI 0.1-0.5; p<0.001) and deep response (OR 0.3, 95% CI 0.2-0.6; p=0.001). CXCR4 mutations (HR 2.0, 95% CI 1.2-3.4; p=0.01) and platelet count 100 K/uL or less (HR 2.5, 95% CI 1.3-4.9; p=0.007) were associated with worse progression-free survival (PFS). We proposed a scoring system using these two factors. The median PFS for patients with zero, one and two risk factors were not reached, 5 years and 3 years (p<0.001). Patients with two risk factors had HR 2.2 (95% CI 1.3-3.8; p=0.004) compared with one factor, and patients with one factor had HR 2.3 (95% CI 1.1-5.1; p=0.03) compared with zero factors. Age 65 years or older was the only factor associated with overall survival (HR 3.2, 95% CI 1.4-7.0; p=0.005). Multiple imputation analyses did not alter our results. Our study confirms the predictive and prognostic value of CXCR4 mutations in patients with WM treated with ibrutinib monotherapy.

The Role of Bruton’s Kinase Inhibitors in Chronic Lymphocytic Leukemia: Current Status and Future Directions

The use of the Bruton’s tyrosine kinase (BTK) inhibitors has changed the management and clinical history of patients with chronic lymphocytic leukemia (CLL). BTK is a critical molecule that interconnects B-cell antigen receptor (BCR) signaling. BTKIs are classified into two categories: irreversible (covalent) inhibitors and reversible (non-covalent) inhibitors. Ibrutinib is the first irreversible BTK inhibitor approved by the U.S. Food and Drug Administration in 2013 as a breakthrough therapy in CLL patients. Subsequently, several studies evaluated the efficacy and safety of new agents with reduced toxicity when compared with ibrutinib. Two other irreversible, second-generation BTK inhibitors, acalabrutinib and zanubrutinib, were developed to reduce ibrutinib-mediated adverse effects. Additionally, new reversible BTK inhibitors are currently under development in an early phase studies to improve their activity and to diminish adverse effects. This review summarizes the pharmacology, clinical efficacy, safety, dosing, drug-drug interactions associated with the treatment of CLL with BTK inhibitors, and examines its further implications.

Infectious complications in patients with chronic lymphocytic leukemia treated with bruton’s tyrosine kinase inhibitors

The aim of this study is to analyze the scientific literature data on the frequency and characteristics of infectious complications during the treatment of patients with lymphoproliferative diseases with a new class of drugs, selective inhibitors of Brutons tyrosine kinase (BTK). This work describes the indications for appointing these drugs as well as the participation of BTK in the development and activation of B cells. We have studied the main characteristics of BTK inhibitors used in clinical practice and associated disorders in the activity of off-target tyrosine kinases. The work describes the main types of known infectious complications developing during the treatment with the drugs of this group, the period of their appearance, and characteristic pathogens.

The Development of BTK Inhibitors: A Five-Year Update

Bruton’s tyrosine kinase (BTK) represented, in the past ten years, an important target for the development of new therapeutic agents that could be useful for cancer and autoimmune disorders. To date, five compounds, able to block BTK in an irreversible manner, have been launched in the market, whereas many reversible BTK inhibitors (BTKIs), with reduced side effects that are more useful for long-term administration in autoimmune disorders, are under clinical investigation. Despite the presence in the literature of many articles and reviews, studies on BTK function and BTKIs are of great interest for pharmaceutical companies as well as academia. This review is focused on compounds that have appeared in the literature from 2017 that are able to block BTK in an irreversible or reversible manner; also, new promising tunable irreversible inhibitors, as well as PROTAC molecules, have been reported. This summary could improve the knowledge of the chemical diversity of BTKIs and provide information for future studies, particularly from the medicinal chemistry point of view. Data reported here are collected from different databases (Scifinder, Web of Science, Scopus, Google Scholar, and Pubmed) using “BTK” and “BTK inhibitors” as keywords.

Design And Synthesis Of Novel Pyrazolopyrimidine-Based Derivatives As Reversible BTK Inhibitors With Potent Antiproliferative Activity In Mantle Cell Lymphoma

Development of Bruton’s tyrosine kinase (BTK) inhibitors is of great value and significance in the treatment of B-cell malignancies and autoimmune diseases. Herein, a novel class of pyrazolopyrimidine-based BTK inhibitors were designed and evaluated in mantle cell lymphoma (MCL) cell lines. We demonstrated that target compounds had made great progress in improvement of antiproliferative activity compared to lead compound. Compounds 13c, 13g, 13h, 13l, 13n and 13o demonstrated effectively antiproliferative activity in MCL cells lines with single-digit micromolar potency. Furthermore, compound 13l specifically disturbed mitochondrial membrane potential and increased reactive oxygen species level in Z138 cells in a dose-dependent manner. 13l induced cell apoptosis through the caspase 3- mediated apoptotic pathway in Z138 cells. Overall, this study provides valuable lead compounds for developing antitumor agents.

Single-Cell Sequencing Demonstrates Complex Resistance Landscape in CLL and MCL Treated with BTK and BCL2 Inhibitors

The genomic landscape of resistance to targeted agents (TAs) used as monotherapy in chronic lymphocytic leukemia (CLL) is complex and often heterogeneous at the patient level. To gain insight into the clonal architecture of acquired genomic resistance to BTK inhibitors and BCL2 inhibitors in CLL, particularly in patients carrying multiple resistance mutations, we performed targeted single-cell DNA sequencing of eight patients who developed progressive disease (PD) on TAs (either class). In all cases, analysis of single-cell architecture revealed mutual exclusivity between multiple resistance mutations to the same TA class, variable clonal co-occurrence of multiple mutations affecting different TAs in patients exposed to both classes, and a phenomenon of multiple independent emergences of identical nucleotide changes leading to canonical resistance mutations. We also report the first observation of established BCL2 resistance mutations in a patient with mantle cell lymphoma (MCL) following PD on sequential monotherapy, implicating BCL2 as a venetoclax resistance mechanism in MCL. Taken together, these data reveal the significant clonal complexity of CLL and MCL progression on TAs at the nucleotide level and confirm the presence of multiple, clonally independent, mechanisms of TA resistance within each individual disease context.