Ibrutinib plus RICE or RVICI for relapsed/refractory mature B-cell non-Hodgkin lymphoma in children and young adults:SPARKLE trial

Part 1 results of the open-label, randomized, global phase 3 SPARKLE trial supported continued assessment of ibrutinib with either modified rituximab, ifosfamide, carboplatin, and etoposide (RICE) or rituximab, vincristine, ifosfamide, carboplatin, idarubicin, and dexamethasone (RVICI) in pediatric patients with relapsed/refractory (R/R) mature B-cell non-Hodgkin lymphoma (B-NHL). We report final results of Part 2 evaluating the efficacy of ibrutinib plus RICE or RVICI vs RICE/RVICI alone. Patients aged 1 to 30 years (initial diagnosis \u3c18 years) were randomized 2:1 to receive ibrutinib with or without RICE/RVICI. Primary endpoint was event-free survival (EFS) based on independent committee-confirmed events. Fifty-one patients were enrolled. Median age was 15 years; Burkitt lymphoma, Burkitt leukemia, and Burkitt-like lymphoma (total: 45%) and diffuse large B-cell lymphoma/primary mediastinal B-cell lymphoma (51%) were the most common subtypes. At the preplanned interim analysis, median EFS was 6.1 vs 7.0 months with ibrutinib plus RICE/RVICI vs RICE/RVICI, respectively (hazard ratio, 0.9; 90% confidence interval, 0.5-1.6; P = .387); further enrollment was ceased. With ibrutinib plus RICE/RVICI vs RICE/RVICI, median overall survival was 14.1 vs 11.1 months, overall response rate was 69% vs 81%, and 46% vs 44% proceeded to stem cell transplantation. In both treatment arms, 100% of patients experienced grade ≥3 treatment-emergent adverse events. No EFS benefit was seen with ibrutinib. Salvage was generally poor in patients who received prior rituximab, regardless of treatment arm. No new safety signals were observed. Ibrutinib exposure in pediatric patients fell within the target range of exposure in adults. Trial is registered on www.clinicaltrials.gov (NCT02703272)

Robust estimation of bacterial cell count from optical density

Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data

Molecular regulation of VEGFR-2 expression and activation in endothelial cells

Thesis (Ph.D.)--Boston University PLEASE NOTE: Boston University Libraries did not receive an Authorization To Manage form for this thesis or dissertation. It is therefore not openly accessible, though it may be available by request. If you are the author or principal advisor of this work and would like to request open access for it, please contact us at [email protected]. Thank you.Angiogenesis, a hallmark step in tumor growth and metastasis, is primarily driven by the action of vascular endothelial growth factor (VEGF) on its receptor, VEGFR-2. Central to its regulation, the abundance of VEGFR-2 on the surface of endothelial cells determines VEGF's ability to stimulate vasculogenesis and pathological angiogenesis. By using a yeast two-hybrid system we have identified PDCL3 (Phosducin like 3) as a novel VEGFR-2 interacting protein that serves as a chaperone protein. PDCL3 expression is highly up-regulated in pathological neovascularization in a mouse model of oxygen-induced proliferative retinopathy and its expression correlates with VEGFR-2 expression. Knockdown of PDCL3 in endothelial cells significantly reduced hypoxia-induced expression of VEGFR-2. Further studies showed that PDCL3 binds to both nascent and mature VEGFR-2 through recognition of its juxtamembrane (JM) domain. Preventing binding of PDCL3 to the JM domain, and manipulating expression of PDCL3 by over-expression and siRNA in endothelial cells, showed that PDCL3 controls the abundance of VEGFR-2 through inhibition of its ubiquitination and degradation. Various in vivo and in vitro angiogenesis assays showed that PDCL3 activity is required for VEGF-mediated endothelial cell proliferation, capillary tube formation, and angiogenesis in developing zebrafish embryos. Further investigation of the molecular mechanisms of VEGFR-2 protein homeostasis revealed that its PEST domain controls degradation and ubiquitination of mature VEGFR-2. The data demonstrate that β-Trcp1 ubiquitin E3 ligase is recruited to the PEST domain and mediates ubiquitination and degradation of VEGFR-2. The PEST domain via phospho-Y1173 also contributes to activation of p38 mitogen-activated protein kinase (p38 MAPK), which results in the stabilization of VEGFR-2. The work demonstrates that VEGFR-2 protein homeostasis in endothelial cells is controlled at multiple levels involving co-chaperone functions of PDCL3, βTrcp1 ubiquitin E3 ligase and p38 MAPK pathway

Immune restoration with ibrutinib plus venetoclax in first-line chronic lymphocytic leukemia : the phase 2 CAPTIVATE study

Fundació CarrerasThis study was supported by Pharmacyclics LLC, an AbbVie Company.We evaluated immune cell subsets in patients with chronic lymphocytic leukemia (CLL) who received first-line therapy with 3 cycles of ibrutinib then 13 cycles of ibrutinib plus venetoclax in the minimal residual disease (MRD) cohort of the CAPTIVATE study (NCT02910583). Patients with Confirmed undetectable MRD (uMRD) were randomly assigned to placebo or ibrutinib groups; patients without Confirmed uMRD were randomly assigned to ibrutinib or ibrutinib plus venetoclax groups. We compared immune cell subsets in samples collected at 7 time points with age-matched healthy donors. CLL cells decreased within 3 cycles after venetoclax initiation; from cycle 16 onward, levels were similar to healthy donor levels (HDL; ≤0.8 cells per μL) in patients with Confirmed uMRD and slightly above HDL in patients without Confirmed uMRD. By 4 months after cycle 16, normal B cells had recovered to HDL in patients randomly assigned to placebo. Regardless of randomized treatment, abnormal counts of T cells, classical monocytes, and conventional dendritic cells recovered to HDL within 6 months (median change from baseline −49%, +101%, and +91%, respectively); plasmacytoid dendritic cells recovered by cycle 20 (+598%). Infections generally decreased over time regardless of randomized treatment and were numerically lowest in patients randomly assigned to placebo within 12 months after cycle 16. Sustained elimination of CLL cells and recovery of normal B cells were confirmed in samples from patients treated with fixed-duration ibrutinib plus venetoclax in the GLOW study (NCT03462719). These results demonstrate promising evidence of restoration of normal blood immune composition with ibrutinib plus venetoclax

Immune restoration with ibrutinib plus venetoclax in first-line chronic lymphocytic leukemia: the phase 2 CAPTIVATE study.

We evaluated immune cell subsets in patients with chronic lymphocytic leukemia (CLL) who received first-line therapy with 3 cycles of ibrutinib then 13 cycles of ibrutinib plus venetoclax in the minimal residual disease (MRD) cohort of the CAPTIVATE study (NCT02910583). Patients with Confirmed undetectable MRD (uMRD) were randomly assigned to placebo or ibrutinib groups; patients without Confirmed uMRD were randomly assigned to ibrutinib or ibrutinib plus venetoclax groups. We compared immune cell subsets in samples collected at 7 time points with age-matched healthy donors. CLL cells decreased within 3 cycles after venetoclax initiation; from cycle 16 onward, levels were similar to healthy donor levels (HDL; ≤0.8 cells per μL) in patients with Confirmed uMRD and slightly above HDL in patients without Confirmed uMRD. By 4 months after cycle 16, normal B cells had recovered to HDL in patients randomly assigned to placebo. Regardless of randomized treatment, abnormal counts of T cells, classical monocytes, and conventional dendritic cells recovered to HDL within 6 months (median change from baseline -49%, +101%, and +91%, respectively); plasmacytoid dendritic cells recovered by cycle 20 (+598%). Infections generally decreased over time regardless of randomized treatment and were numerically lowest in patients randomly assigned to placebo within 12 months after cycle 16. Sustained elimination of CLL cells and recovery of normal B cells were confirmed in samples from patients treated with fixed-duration ibrutinib plus venetoclax in the GLOW study (NCT03462719). These results demonstrate promising evidence of restoration of normal blood immune composition with ibrutinib plus venetoclax

Hypoxia-induced expression of phosducin-like 3 regulates expression of VEGFR-2 and promotes angiogenesis

Expression and activation of vascular endothelial growth factor receptor 2 (VEGFR-2) by VEGF ligands are the main events in the stimulation of pathological angiogenesis. VEGFR-2 expression is generally low in the healthy adult blood vessels, but its expression is markedly increased in the pathological angiogenesis. In this report, we demonstrate that phosducin-like 3 (PDCL3), a recently identified chaperone protein involved in the regulation of VEGFR-2 expression, is required for angiogenesis in zebrafish and mouse. PDCL3 undergoes N-terminal methionine acetylation, and this modification affects PDCL3 expression and its interaction with VEGFR-2. Expression of PDCL3 is regulated by hypoxia, the known stimulator of angiogenesis. The mutant PDCL3 that is unable to undergo N-terminal methionine acetylation was refractory to the effect of hypoxia. The siRNA-mediated silencing of PDCL3 decreased VEGFR-2 expression resulting in a decrease in VEGF-induced VEGFR-2 phosphorylation, whereas PDCL3 over-expression increased VEGFR-2 protein. Furthermore, we show that PDCL3 protects VEGFR-2 from misfolding and aggregation. The data provide new insights for the chaperone function of PDCL3 in angiogenesis and the roles of hypoxia and N-terminal methionine acetylation in PDCL3 expression and its effect on VEGFR-2

Clinical impact of ibrutinib plus R-CHOP in untreated DLBCL co-expressing BCL2 and MYC in the phase 3 PHOENIX trial

Diffuse large B-cell lymphoma (DLBCL), with high coexpression of BCL2 and MYC proteins (DE lymphoma), is considered an adverse prognostic indicator associated mostly with non-germinal center B-cell–like (non-GCB) DLBCL. BCL2/MYC overexpression is associated with B-cell receptor (BCR) pathway activation; consequently, DE DLBCL may be sensitive to BCR inhibitors. We assessed whether high BCL2/MYC coexpression by RNA sequencing could identify a patient subset responsive to ibrutinib using baseline biopsies from the PHOENIX trial, which evaluated the addition of ibrutinib to rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP) in untreated non-GCB DLBCL. BCL2/MYC RNA expression was correlated with lower event-free survival (EFS) and overall survival (OS) using Kaplan–Meier estimates with Cox regression and log-rank testing. In total, 234 of 766 (30.5%) patients had high BCL2/MYC coexpression: 123 of 386 (31.9%) received ibrutinib plus R-CHOP and 111 of 380 (29.2%) received R-CHOP. EFS was superior with ibrutinib plus R-CHOP compared with R-CHOP alone in patients with high BCL2/MYC coexpression, but there was no significant impact on OS. However, EFS and OS showed clinically meaningful improvement with ibrutinib plus R-CHOP over R-CHOP alone in patients aged &lt;60 years with high BCL2/MYC coexpression. We observed a significant association between high BCL2/MYC coexpression and activated B-cell-like and MYD88 L265P/CD79B-mutated subtypes of DLBCL. Consequently, high BCL2/MYC coexpression identified a subset of non-GCB DLBCL that may be preferentially responsive to ibrutinib and warrants further investigation. This trial was registered at www.clinicaltrials.gov as #NCT01855750. </p