ALBERT

Description: Multiple myeloma (MM) expands in the bone marrow and causes devastating bone destruction by enhancing osteoclastic bone resorption in its vicinity, suggesting a close interaction between MM cells and osteoclasts (OCs). Here, we show that peripheral blood mononuclear cell-derived OCs enhanced growth and survival of primary MM cells as well as MM cell lines more potently than stromal cells, and that OCs protected MM cells from apoptosis induced by serum depletion or doxorubicin. OCs produced osteopontin (OPN) and interleukin 6 (IL-6), and adhesion of MM cells to OCs increased IL-6 production from OCs. In addition, IL-6 and OPN in combination enhanced MM cell growth and survival. However, the effects of OCs on MM cell growth and survival were only partially suppressed by a simultaneous addition of anti–IL-6 and anti-OPN antibodies and were completely abrogated by inhibition of cellular contact between MM cells and OCs. These results demonstrate that OCs enhance MM cell growth and survival through a cell-cell contact-mediated mechanism that is partially dependent on IL-6 and OPN. It is suggested that interactions of MM cells with OCs augment MM growth and survival and, thereby, form a vicious cycle, leading to extensive bone destruction and MM cell expansion.

Description: Background: The human leukocyte antigen (HLA)-G molecule exhibits limited tissue distribution and exerts multiple immunoregulatory functions. Recent studies indicate an ectopic up-regulation in tumor cells which may favor their escape from antitumor immune responses. The role of HLA-G in B cell chronic lymphocytic leukemia (B-CLL) has not been defined. Experimental design: HLA-G expression was studied retrospectively in circulating B-CLL cells from 47 patients by flow cytometry using the MEM/G9 monoclonal antibody. Results: The proportion of leukemic cells expressing HLA-G varied from 1% to 54%. Patients with 〈 23% HLA-G positive cells (according to ROC analysis; designated as the HLA-G negative group) had a significantly longer progression-free survival (PFS) time than patients with 〉 23% of positive cells (median PFS 120 versus 23 months, p=0.0001). Multivariate analysis revealed that HLA-G expression (hazard ratio 4.81; p=0.002) was next to the initial staging according to Binet (hazard ratio 8.6; p=0.0001) the best independent prognostic factor compared to other known prognostic factors like ZAP-70 status (hazard ratio 3.6; p=0.029) or CD38 status (hazard ratio 1.83; p=0.37). Humoral and cellular immunosuppression was significantly more prominent in HLA-G positive as compared to HLA-G negative patients group (median immunglobuline G (g/l) 4.3 versus 7.3; median total T-cells (per μl) 824 versus 2540). Conclusions: In B-CLL the level of HLA-G expression is correlated with the degree of immunosuppression and prognosis. To our knowledge this is the first report that describes an association of HLA-G antigen expression and the course of the disease in B-CLL patients. Thus, HLA-G may contribute to the impairment of immune responses against tumor cells and infections. These findings need to be confirmed in a prospective study.

Description: We have investigated the role of the Rho and Rac family small guanine triphosphate (GTP) exchange factors (RhoGEFs), Vav1 and Vav2, in the activation of platelets by the immunoreceptor tyrosine-based activation motif (ITAM)–coupled collagen receptor GPVI and by the G protein–coupled receptor agonist thrombin. The glycoprotein VI (GPVI)–specific agonist collagen-related peptide (CRP) and thrombin stimulated tyrosine phosphorylation of Vav1 but not Vav2 in human platelets. Surprisingly, however, CRP did not activate the low-molecular-weight G protein Rac and stimulated only a small increase in activity of p21-associated kinase 2 (PAK2), despite the fact that both proteins are regulated downstream of Vav1 in other cells. Further, activation of Rac and PAK2 by thrombin was maintained in platelets from mice deficient in Vav1. Activation of phospholipase C (PLC) by GPVI and thrombin was unaltered in Vav1-, Vav2-, and Vav1/Vav2-deficient platelets. A weak inhibition of late-stage aggregation to CRP and thrombin was observed in platelets deficient in Vav1 but not Vav2, whereas spreading on fibrinogen was not changed. The present results demonstrate that neither Vav1 nor Vav2 lie upstream of PLC or Rac in platelets, highlighting an important difference in their role in signaling by ITAM-coupled receptors in other cell types. The present study has provided evidence for a possible role of Vav1 but not Vav2 in the later stages of platelet aggregation.

Description: Background:Ibrutinib, a potent inhibitor of Bruton's tyrosine kinase, is indicated for the treatment of mantle cell lymphoma, chronic lymphocytic leukemia/small lymphocytic lymphoma (including 17p deletion), and Waldenström's macroglobulinemia. Because ibrutinib is extensively cleared by cytochrome P450 (CYP) 3A4, concomitant treatment with CYP3A inhibitors has been shown to increase ibrutinib exposure in healthy adults. However, sparse PK data from uncontrolled phase 2 studies with moderate CYP3A inhibitors showed a lower magnitude of drug-drug interactions (DDI) than observed in studies with healthy subjects or in silico simulations under nonfasted conditions (data on file). This phase 1 study was conducted to evaluate potential DDIs between ibrutinib and CYP3A inhibitors in patients with B-cell malignancies and to confirm recommended dose adjustments. Methods: This was an open-label, multicenter, DDI study of ibrutinib with erythromycin (moderate CYP3A inhibitor) and voriconazole (strong CYP3A inhibitor) in patients (≥ 18 years) with relapsed/refractory B-cell malignancy. During the first treatment cycle, patients received an oral dose of 560 mg ibrutinib on days 1-4 (steady-state) and days 14-18. On days 5-13 and 19-27, the dose was reduced to 140 mg ibrutinib and combined with erythromycin (500 mg tid on days 5-11) and then with voriconazole (200 mg bid on days 19-25). On PK sampling days (days 4 [alone], 11 [with erythromycin], and 25 [with voriconazole]), ibrutinib was administered 30 min before a standard breakfast. On these PK sampling days, the morning doses of voriconazole and erythromycin were administered 1 hr prior to ibrutinib and together with ibrutinib, respectively. PK samples were taken pre- and up to 24 hr postdose; key PK parameters were summarized for ibrutinib, PCI-45227 (ibrutinib metabolite), erythromycin, and voriconazole. After completion of the DDI assessment during cycle 1, patients continued treatment with ibrutinib monotherapy at therapeutic doses. Safety was evaluated throughout the study. Results:All patients (N = 26) completed the PK assessments in cycle 1; 54% were men, and the median age was 65 years. The geometric mean ratio (GMR) for dose-normalized maximum concentration (Cmax) and area under the plasma concentration-time curve from time 0 to 24 hr (AUC24h) for ibrutinib was 3.35 and 2.99, respectively, when given in combination with erythromycin (Table). When ibrutinib was coadministered with voriconazole, the GMR for Cmax and AUC24h was 6.71 and 5.74, respectively (Table). Four out of 26 patients showed either no interaction between ibrutinib and erythromycin or a lower ibrutinib exposure (AUC ratios 0.27-0.99). Three of these 4 patients also displayed minimal interaction with voriconazole (AUC ratios 1.08-1.96); baseline ibrutinib AUCs for the 3 patients were at the high end of the range, indicating lower CYP3A abundance and thus less impact from CYP inhibition. Physiologically-based PK modeling under fed conditions predicted a 5.5- and 7.1-fold increase in the GMR for ibrutinib Cmax and AUC, respectively, when dosed with erythromycin and an increase of 6.3- and 7.6-fold, respectively, when dosed with voriconazole. The simulated interaction factor for voriconazole is contained in the 90% CI of the observed GMRs (borderline for AUC), whereas the model over-predicted Cmax and AUC by ~50% and ~130%, respectively. Treatment-emergent adverse events (TEAEs) were reported in 22/26 patients (85%); The most common TEAEs (all causality, ≥ 10% of patients) were diarrhea (27%); neutropenia (23%); abdominal pain, fatigue, pyrexia, and thrombocytopenia (15% each); anemia, dry mouth, cough, dyspnea, and hypertension (12% each). Drug-related TEAEs ≥ grade 3 were neutropenia (15.4%); hypertension (7.7%); and diarrhea, thrombocytopenia, herpes zoster, cough, dyspnea, atrial fibrillation, and cardiac failure (3.8% each). Conclusions:PK data indicate that 140 mg ibrutinib, when combined with a moderate or strong CYP3A inhibitor, achieved exposures generally consistent with those after a 560 mg dose given alone. Coadministration of 140 mg ibrutinib with erythromycin or voriconazole demonstrated an acceptable safety profile, and the adverse event profile was consistent with the ibrutinib safety profile at therapeutic doses. These findings support the 140 mg/day ibrutinib dose when given in combination with erythromycin or voriconazole. Disclosures de Jong: Janssen: Employment. Hellemans:Janssen: Employment, Equity Ownership. De Wilde:Janssen: Employment. Patricia:Janssen: Employment. Masterson:Janssen: Employment. Osmanov:Seattle Genetics: Research Funding. Cordoba:Janssen: Research Funding, Speakers Bureau. Panizo:Roche Pharmaceuticals: Speakers Bureau; Janssen: Membership on an entity's Board of Directors or advisory committees; Takeda: Membership on an entity's Board of Directors or advisory committees. de Zwart:Janssen: Employment. Snoeys:Janssen: Employment, Equity Ownership. Chauhan:Janssen: Consultancy. Jiao:Janssen: Employment. Sukbuntherng:Pharmacyclics, LLC: Employment, Equity Ownership; Global Blood Therapeutics: Equity Ownership. Ouellet:Janssen: Employment.

Description: Multiple myeloma (MM) cells cause devastating bone destruction by activating osteoclasts in the bone marrow milieu. However, the mechanism of enhanced bone resorption in patients with myeloma is poorly understood. In the present study, we investigated a role of C-C chemokines, macrophage inflammatory protein (MIP)–1α and MIP-1β, in MM cell-induced osteolysis. These chemokines were produced and secreted by a majority of MM cell lines as well as primary MM cells from patients. Secretion of MIP-1α and MIP-1β correlated well with the ability of myeloma cells to enhance osteoclastic bone resorption both in vitro and in vivo as well as in MM patients. In osteoclastogenic cultures of rabbit bone cells, cocultures with myeloma cells as well as addition of myeloma cell-conditioned media enhanced both formation of osteoclastlike cells and resorption pits to an extent comparable to the effect of recombinant MIP-1α and MIP-1β. Importantly, these effects were mostly reversed by neutralizing antibodies against MIP-1α and MIP-1β, or their cognate receptor, CCR5, suggesting critical roles of these chemokines. We also demonstrated that stromal cells express CCR5 and that recombinant MIP-1α and MIP-1β induce expression of receptor activator of nuclear factor-κB (RANK) ligand by stromal cells, thereby stimulating osteoclast differentiation of preosteoclastic cells. These results suggest that MIP-1α and MIP-1β may be major osteoclast-activating factors produced by MM cells.

Description: Wiskott Aldrich syndrome (WAS) is an X-linked recessive disorder associated with abnormalities in platelets and lymphocytes giving rise to thrombocytopenia and immunodeficiency. WAS is caused by a mutation in the gene encoding the cytoskeletal protein (WASp). Despite its importance, the role of WASp in platelet function is not established. WASp was recently shown to undergo tyrosine phosphorylation in platelets after activation by collagen, suggesting that it may play a selective role in activation by the adhesion molecule. In the present study, we show that WASp is heavily tyrosine phosphorylated by a collagen-related peptide (CRP) that binds to the collagen receptor glycoprotein (GP) VI, but not to the integrin 2β1. Tyrosine phosphorylation of WASp was blocked by Src family kinase inhibitors and reduced by treatment with wortmannin and in patients with X-linked agammaglobulinemia (XLA), a condition caused by a lack of functional expression of Btk. This indicates that Src kinases, phosphatidylinositol 3-kinase (PI 3-kinase), and Btk all contribute to the regulation of tyrosine phosphorylation of WASp. The functional importance of WASp was investigated in 2 WAS brothers who show no detectable expression of WASp. Platelet aggregation and secretion from dense granules induced by CRP and thrombin was slightly enhanced in the WAS platelets relative to controls. Furthermore, there was no apparent difference in morphology in WAS platelets after stimulation by these agonists. These observations suggest that WASp does not play a critical role in intracellular signaling downstream of tyrosine kinase-linked and G protein-coupled receptors in platelets.

Description: Light transmission aggregometry (LTA) is used worldwide for the investigation of heritable platelet function disorders (PFDs), but interpretation of results is complicated by the feedback effects of ADP and thromboxane A2 (TxA2) and by the overlap with the response of healthy volunteers. Over 5 years, we have performed lumi-aggregometry on 9 platelet agonists in 111 unrelated research participants with suspected PFDs and in 70 healthy volunteers. Abnormal LTA or ATP secretion test results were identified in 58% of participants. In 84% of these, the patterns of response were consistent with defects in Gi receptor signaling, the TxA2 pathway, and dense granule secretion. Participants with defects in signaling to Gq-coupled receptor agonists and to collagen were also identified. Targeted genotyping identified 3 participants with function-disrupting mutations in the P2Y12 ADP and TxA2 receptors. The results of the present study illustrate that detailed phenotypic analysis using LTA and ATP secretion is a powerful tool for the diagnosis of PFDs. Our data also enable subdivision at the level of platelet-signaling pathways and in some cases to individual receptors. We further demonstrate that most PFDs can be reliably diagnosed using a streamlined panel of key platelet agonists and specified concentrations suitable for testing in most clinical diagnostic laboratories.

Description: The hyaluronan-mediated motility receptor (HMMR/Rhamm) is overexpressed in numerous tumor types, including acute lymphoid leukemia and acute myeloid leukemia (AML). Several studies have reported the existence of T-cell responses directed against HMMR in AML patients that are linked to better clinical outcome. Therefore, we explored the use of HMMR-specific TCRs for transgenic expression in lymphocytes and their in vivo impact on HMMR+ solid tumors and disseminated leukemia. We obtained TCRs via an in vitro priming approach in combination with CD137-mediated enrichment. Recipient lymphocytes expressing transgenic TCR revealed the specific tumor recognition pattern seen with the original T cells. Adoptive transfer experiments using a humanized xenograft mouse model resulted in significantly retarded solid tumor outgrowth, which was enhanced using IL-15–conditioned, TCR-transgenic effector memory cells. These cells also showed an increased potency to retard the outgrowth of disseminated AML, and this was further improved using CD8-enriched effector memory cells. To define a safe clinical setting for HMMR-TCR gene therapy, we analyzed transgenic T-cell recognition of hematopoietic stem cells (HSCs) and found on-target killing of HLA-A2+ HSCs. Our findings clearly limit the use of HMMR-TCR therapy to MHC- mismatched HSC transplantation, in which HLA-A2 differences can be used to restrict recognition to patient HSCs and leukemia.

Description: Despite potential clinical importance, target cells for mother-to-child transmission of HIV-1 have not yet been identified. Cord blood–derived CD4+ T cells are largely naive and do not express CCR5, the mandatory coreceptor for transmitted HIV-1 R5 strains in infants. In the present study, we demonstrate that in the human fetal and infant gut mucosa, there is already a large subset of mucosal memory CD4+CCR5+ T cells with predominantly a Th1 and Th17 phenotype. Using next-generation sequencing of the TCRβ chain, clonally expanded T cells as a hallmark for memory development predominated in the gut mucosa (30%), whereas few were found in the lymph nodes (1%) and none in cord blood (0%). The gut mucosal fetal and infant CD4+ T cells were highly susceptible to HIV-1 without any prestimulation; pol proviral DNA levels were similar to infected phytohemagglutinin-stimulated adult PBMCs. In conclusion, in the present study, we show that extensive adaptive immunity is present before birth and the gut mucosa is the preferential site for memory CD4+ T cells. These CD4+CCR5+ T cells in the infant mucosa provide a large pool of susceptible cells for ingested HIV-1 at birth and during breastfeeding, indicating a mucosal route of mother-to-child transmission that can be targeted in prevention strategies.