B-cell receptor (BCR) signaling is a critical pathway in the pathogenesis of several B-cell malignancies, including chronic lymphocytic leukemia (CLL), and can be targeted by inhibitors of BCRassociated kinases, such as Bruton tyrosine kinase (Btk). PCI-32765, a selective, irreversible Btk inhibitor, is a novel, molecularly targeted agent for patients with B-cell malignancies, and is particularly active in patients with CLL. In this study, we analyzed the mechanism of action of PCI-32765 in CLL, using in vitro and in vivo models, and performed correlative studies on specimens from patients receiving therapy with PCI-32765. PCI-32765 significantly inhibited CLL cell survival, DNA synthesis, and migration in response to tissue homing chemokines (CXCL12, CXCL13 IntroductionChronic lymphocytic leukemia (CLL), the most common leukemia in western societies, is characterized by the accumulation of mature, CD5 ϩ CD23 ϩ monoclonal B lymphocytes in the blood, secondary lymphatic tissues, and the bone marrow. 1 Proliferating CLL cells, which account for approximately 0.1% to 1% of the CLL clone, 2 are typically found within microanatomical structures called proliferation centers or pseudofollicles, 3 where CLL cells interact with accessory cells (ie, stromal cells or T cells), thereby receiving survival and growth signals. 4 Such external signals from the leukemia microenvironment can supplement intrinsic oncogenic lesions, thereby promoting maintenance and expansion of the CLL clone. 3,5,6 Among the various external stimuli in the tissue microenvironments, B-cell receptor (BCR) activation and signaling, particularly in lymphatic tissues, 6 is a central pathologic mechanism, even though the precise mechanism of BCR stimulation and the nature of the antigen(s) that activate the BCRs remain obscure. 1,7 The most direct evidence for the importance of BCR signaling in CLL comes from recent comparative gene expression profiling (GEP) data that revealed BCR signaling as the most prominent pathway activated in CLL cells isolated from lymphatic tissues. 6 These GEP changes displayed remarkable similarity to GEP changes of CLL cells cocultured with monocyte-derived nurselike cells (NLC), 8 a system for studying the impact of the lymphatic tissue microenvironment in CLL in vitro. Additional evidence for the importance of BCR signaling in CLL comes from the observation that important CLL risk factors have functional links to the BCRs. The mutation status of the IgV H segments of the BCR distinguishes "mutated" (M-CLL) from "unmutated" CLL (U-CLL), with a low or high risk for disease progression, respectively, each accounting for approximately 50% of the patients. ZAP-70 is predominantly expressed in U-CLL cases, 9 and ZAP-70 expression is associated with enhanced BCR signaling. 10 Furthermore, CLL patients express restricted sets of BCRs, as determined by BCR sequencing. These BCRs have immunoglobulin (Ig) heavy-chain variable (V) gene sequences that are identical or stereotyped in subsets of patients, 11,12 suggesting that these BCR...

Highly porous titanium structures are widely used for maxillofacial and orthopedic surgery because of their excellent mechanical properties similar to those of human bone and their facilitation of bone ingrowth. In contrast to common methods, the generation of porous titaniumproducts by selective electron beam melting (SEBM), an additive manufacturing technology, overcomes difficulties concerning the extreme chemical affinity of liquid titanium to atmospheric gases which consequently leads to strongly reduced ductility of the metal. The purpose of this study was to assess the suitability of a smooth compact and a porous Ti-6Al-4V structure directly produced by the SEBM process as scaffolds for bone formation. SEBM-processed titanium implants were placed into defects in the frontal skull of 15 domestic pigs. To evaluate the direct contact between bone and implant surfaces and to assess the ingrowth of osseous tissue into the porous structure, microradiographs and histomorphometric analyses were performed 14, 30, and 60 days after surgery. Bone ingrowth increased significantly during the period of this study. After 14 days the most outer regions of the implants were already filled with newly formed bone tissue (around 14%). After 30 days the bone volume inside the implants reached almost 30% and after 60 days abundant bone formation inside the implants attained 46%. During the study only scarce bone-implant contact was found around all implants, which did not exceed 9% around compact specimens and 6% around porous specimens after 60 days. This work demonstrates that highly porous titanium implants with excellent interconnectivity manufactured using the SEBM method are suitable scaffolds for bone ingrowth. This technique is a good candidate for orthopedic and maxillofacial applications.

The aim of the study was to assess the suitability of different Ti-6Al-4V surfaces produced by the electron beam melting (EBM) process as matrices for attachment, proliferation, and differentiation of human fetal osteoblasts (hFOB 1.19). Human osteoblasts were cultured in vitro on smooth and rough-textured Ti-6Al-4V alloy disks. By means of cell number and vitality and SEM micrographs cell attachment and proliferation were observed. The differentiation rate was examined by using quantitative real-time PCR analysis for the gene expression of alkaline phosphatase (ALP), type I collagen (Coll-I), bone sialoprotein (BSP) and osteocalcin (OC). After 3 days of incubation there was a significant higher vitality (p < 0.02) and proliferation (p < 0.02) of hFOB cells on smooth surfaces (R(a) = 0.077 microm) and compact surfaces with adherent partly molten titanium particles on the surface (R(a) /= 56.9 microm) reduced proliferation of hFOB cells. Surface characteristics of titanium can easily be changed by EBM in order to further improve proliferation.

In addition to HLA, recent genome-wide association studies (GWASs) of Hodgkin's lymphoma (HL) have identified susceptibility loci for HL at 2p16.1, 8q24.21 and 10p14. In this study, we perform a GWAS meta-analysis with published GWAS (totalling 1,465 cases and 6,417 controls of European background), and follow-up the most significant association signals in 2,024 cases and 1,853 controls. A combined analysis identifies new HL susceptibility loci mapping to 3p24.1 (rs3806624; P ¼ 1.14 Â 10 À 12 , odds ratio (OR) ¼ 1.26) and 6q23.3 (rs7745098; P ¼ 3.42 Â 10 À 9 , OR ¼ 1.21). rs3806624 localizes 5 0 to the EOMES (eomesodermin) gene within a p53 response element affecting p53 binding. rs7745098 maps intergenic to HBS1L and MYB, a region previously associated with haematopoiesis. These findings provide further insight into the genetic and biological basis of inherited susceptibility to HL.

Discovery of Bruton's tyrosine kinase (BTK) mutations as the cause for X-linked agammaglobulinemia was a milestone in understanding the genetic basis of primary immunodeficiencies. Since then, studies have highlighted the critical role of this enzyme in B-cell development and function, and particularly in B-cell receptor signaling. Because its deletion affects mostly B cells, BTK has become an attractive therapeutic target in autoimmune disorders and B-cell malignancies. Ibrutinib (PCI-32765) is the most advanced BTK inhibitor in clinical testing, with ongoing phase III clinical trials in patients with chronic lymphocytic leukemia and mantle-cell lymphoma. In this article, we discuss key discoveries related to BTK and clinically relevant aspects of BTK inhibitors, and we provide an outlook into clinical development and open questions regarding BTK inhibitor therapy.