Affymetrix SNP array data for chronic lymphoblastic leukemia samples
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ABSTRACT: Ibrutinib (Ibr), an orally administered covalent inhibitor of Bruton’s kinase, has generated remarkable responses in CLL patients including those with an unfavorable cytogenetic profile. Once patients develop resistance to ibrutinib, the outcome is poor with few treatment options. To further understand the genomic mechanisms underlying Ibr resistance, we’ve performed genome wide copy number analysis of serial samples collected from nine ibrutinib-relapsed patients. Deletions of 18p often coincide with del(17p)/TP53 mutations, predispose patients to relapse.
Project description:Diffuse large B-cell lymphoma (DLBCL) and follicular lymphoma (FL) are the most prevalent B-lymphocyte neoplasms in which abnormal activation of the Bruton’s tyrosine kinase (BTK)–mediated B-cell receptor (BCR) signaling pathway contributes to pathogenesis. Ibrutinib is an oral covalent BTK inhibitor that has shown some efficacy in both indications. To improve ibrutinib efficacy through combination therapy, we first investigated differential gene expression in parental and ibrutinib-resistant cell lines to better understand the mechanisms of resistance. Ibrutinib-resistant TMD8 cells had higher BCL2 gene expression and increased sensitivity to ABT-199, a BCL-2 inhibitor. Consistently, clinical samples from ABC-DLBCL patients who experienced poorer response to ibrutinib had higher BCL2 gene expression. We further demonstrated synergistic growth suppression by ibrutinib and ABT-199 in multiple ABC-DLBCL, GCB-DLBCL, and FL lymphoma cell lines. The combination of both drugs also reduced colony formation, increased apoptosis, and inhibited tumor growth in a TMD8 xenograft model. A synergistic combination effect was also found in ibrutinib-resistant cells generated by either genetic mutation or drug treatment. Together, these findings suggest a potential clinical benefit from ibrutinib and ABT-199 combination therapy.
Project description:Diffuse large B-cell lymphoma (DLBCL) and follicular lymphoma (FL) are the most prevalent B-lymphocyte neoplasms in which abnormal activation of the Bruton’s tyrosine kinase (BTK)–mediated B-cell receptor (BCR) signaling pathway contributes to pathogenesis. Ibrutinib is an oral covalent BTK inhibitor that has shown some efficacy in both indications. To improve ibrutinib efficacy through combination therapy, we first investigated differential gene expression in parental and ibrutinib-resistant cell lines to better understand the mechanisms of resistance. Ibrutinib-resistant TMD8 cells had higher BCL2 gene expression and increased sensitivity to ABT-199, a BCL-2 inhibitor. Consistently, clinical samples from ABC-DLBCL patients who experienced poorer response to ibrutinib had higher BCL2 gene expression. We further demonstrated synergistic growth suppression by ibrutinib and ABT-199 in multiple ABC-DLBCL, GCB-DLBCL, and FL lymphoma cell lines. The combination of both drugs also reduced colony formation, increased apoptosis, and inhibited tumor growth in a TMD8 xenograft model. A synergistic combination effect was also found in ibrutinib-resistant cells generated by either genetic mutation or drug treatment. Together, these findings suggest a potential clinical benefit from ibrutinib and ABT-199 combination therapy.
Project description:Bruton’s tyrosine kinase (BTK) inhibitors such as ibrutinib represent an effective strategy for treatment of chronic lymphocytic leukemia (CLL), although ~30% of patients eventually undergo disease progression. Here we investigated the long-term modulation of the CXCR4dim/CD5bright proliferative fraction (PF) and the CXCR4bright/CD5dim resting fraction (RF) in CLL samples, and their correlation with therapeutic outcome and emergence of ibrutinib resistance. Longitudinal tracking by flow cytometry revealed that PF, initially suppressed by ibrutinib, reappeared upon early disease progression suggesting that PF evaluation could represent a sensitive and specific marker of CLL progression upon ibrutinib treatment. Transcriptomic analyses of PF at progression revealed similar proliferation signatures between pre- and post-treatment PF, demonstrating the emergence upon progression of a newly proliferating cell population.
Project description:<p>We analyzed clonal evolution in serial samples from five CLL patients who became resistant to the Bruton's tyrosine kinase (BTK) inhibitor ibrutinib, using whole-exome and deep targeted sequencing. We observe a BTK-C481S mutation in one of five patients, and multiple PLCG2 mutations in a second patient. The other patients had an expansion of clones harboring del(8p) carrying additional driver mutations (EP300, MLL2, EIF2A), with one patient developing trans-differentiation into CD19-negative histiocytic sarcoma. We calculated the growth kinetics of ibrutinib-resistant subclones and estimated the size of the resistant clones at treatment initiation, which we validated by droplet-microfluidic technology. Haplo-insufficiency of TRAIL-R, a consequence of del(8p), led to TRAIL insensitivity which may contribute to development of ibrutinib resistance. These findings demonstrate that ibrutinib therapy has the potential to lead to clonal selection and expansion of rare cell populations already present at the time of treatment initiation. They also provide insight into the heterogeneity of genetic changes associated with ibrutinib resistance, previously attributed solely to mutations in BTK and related pathway molecules.</p>
Project description:The covalent Bruton’s Tyrosine Kinase (BTK) inhibitor ibrutinib is highly efficacious against multiple B-cell malignancies. However, it also has off-target effects and multiple mechanisms of resistance, including the C481S mutation. We hypothesized that small molecule-induced BTK degradation might be able to overcome some of the limitations of traditional enzymatic inhibitors. Here, we demonstrate that BTK degradation results in more durable suppression of signaling and proliferation in cancer cells than BTK inhibition and that BTK degraders are able to efficiently degrade BTK C481S. Moreover, we generated DD-03-171, an optimized lead compound that exhibits enhanced anti-proliferative effects on mantle cell lymphoma (MCL) cells in vitro as well as efficacy in a patient-derived xenograft model of MCL. These data suggest that targeted BTK degradation is an effective therapeutic approach in treating MCL and overcoming ibrutinib resistance, thereby addressing a major unmet need in the treatment of MCL and other B-cell lymphomas.
Project description:Inhibition of Bruton’s tyrosine kinase (BTK) has proven to be highly effective in the treatment of B-cell malignancies such as chronic lymphocytic leukemia (CLL), autoimmune disorders and multiple sclerosis. Since the approval of the first BTK inhibitor (BTKi), Ibrutinib, several other inhibitors including Acalabrutinib, Zanubrutinib, Tirabrutinib and Pirtobrutinib have been clinically approved. All are covalent active site inhibitors, with the exception of the reversible active site inhibitor Pirtobrutinib. The large number of available inhibitors for the BTK target creates challenges in choosing the most appropriate BTKi for treatment. Side-by-side comparisons in CLL have shown that different inhibitors may differ in their treatment efficacy. Moreover, the nature of the resistance mutations that arise in patients appears to depend on the specific BTKi administered. We have previously shown that Ibrutinib binding to the kinase active site causes unanticipated long-range effects on the global conformation of BTK (Joseph, R.E., et al., 2020, https://doi.org/10.7554/eLife.60470). Here we show that binding of each of the five approved BTKi to the kinase active site brings about distinct allosteric changes that alter the conformational equilibrium of full-length BTK. Additionally, we provide an explanation for the resistance mutation bias observed in CLL patients treated with different BTKi and characterize the mechanism of action of two common resistance mutations: BTK T474I and L528W.
Project description:We performed whole genome profiling in order to determine the landscape of genetic alterations assoicated with a subset of CLL that is characterized by deletions in 17p The number of copy number alterations predicted shorter time to treatment among patients untreated at sampling. Chromosome 3p, 4p, and 9p were frequently deleted in del(17p) CLL and strongly associated with shorter OS. We conclude that del(17p) has a unique genomic profile characterized typically by TP53 mutation with novel CNAs and novel drivers, with increasing genomic complexity of any type associated with worse overall survival.
Project description:Cytogenetics abnormalities (CA) are known to be the preponderant prognostic factor in multiple myeloma (MM). Our team has recently developeda prognostic score based on 6 CA, where del(1p32) appears to be the second worst abnormality after del(17p). The aim of this study was to confirm the adverse impact of 1p32 deletion on newly-diagnosed multiple myeloma (NDMM) patients. Among 2551 NDMM patients, 11% were harboring del(1p32). Their overall survival (OS) was half as long as the OS of patients without del(1p32) (49 months vs. 124 months). Likewise, progression-free survival was significantly shorter. More importantly, double-deletion of the 1p32 locus conferred a dramatically poorer prognosis than a monoallelic del(1p32) (OS: 25 months vs. 60 months). As expected, the OS of del(1p32) patients significantly decreased when this abnormality was associated with other high-risk CA (del(17p), t(4;14) or gain(1q)). In the multivariate analysis, del(1p32) appeared as a negative prognostic factor; after adjustment for age and treatment, the risk of progression was 1.3 times higher among patients harboring del(1p32), and the risk of death was 1.9 times higher. At the dawn of risk-adapted treatment strategies, we have confirmed the adverse impact of del(1p32) in MM and the relevance of its assessment at diagnosis.
Project description:Bruton’s tyrosine kinase (BTK) is targeted in the treatment of B-cell disorders including leukemias and lymphomas. Currently approved BTK inhibitors, including Ibrutinib, a first-in-class covalent inhibitor of BTK, bind directly to the kinase active site. While effective at blocking the catalytic activity of BTK, consequences of drug binding on the global conformation of full-length BTK are unknown. Here we uncover a range of conformational effects in full-length BTK induced by a panel of active site inhibitors, including unexpected shifts in the conformational equilibria of the regulatory domains. Additionally, we find that a remote Ibrutinib resistance mutation, T316A in the BTK SH2 domain, drives spurious BTK activity by destabilizing the compact autoinhibitory conformation of full-length BTK, shifting the conformational ensemble away from the autoinhibited form. Future development of BTK inhibitors will need to consider long-range allosteric consequences of inhibitor binding, including the emerging application of these BTK inhibitors in treating COVID-19.
Project description:Diffuse large B cell lymphoma (DLBCL) is the most common aggressive B cell lymphoma and accounts for nearly 40% of cases of B cell non-Hodgkin lymphoma. DLBCL is generally treated with R-CHOP chemotherapy, but many patients do not respond or relapse after treatment. Here, we analyzed the therapeutic potential of the tumor suppressor microRNA-28 (miR-28) for DLBCL, alone and in combination with the Bruton’s tyrosine kinase inhibitor ibrutinib. Combination therapy with miR-28 plus ibrutinib potentiated the anti-tumor effects of monotherapy with either agent by inducing a specific transcriptional cell-cycle arrest program that impairs DNA replication. The molecular actions of miR-28 and ibrutinib synergistically impair DNA replication by simultaneous inhibition of origin activation and fork progression. Moreover, we found that downregulation of the miR-28-plus-ibrutinib gene signature correlates with better survival of ABC-DLBCL patients. These results provide evidence for the effectiveness of a new miRNA-based ibrutinib combination therapy for DLBCL and unveil the miR-28-plus-ibrutinib gene signature as a new predictor of outcome in ABC-DLBCL patients.