Exposure-response analysis of rilotumumab in gastric cancer: the role of tumour MET expression.

BACKGROUND: Rilotumumab, an investigational, monoclonal antibody, inhibits MET-mediated signalling. In a randomized phase 2 trial of rilotumumab±epirubicin/cisplatin/capecitabine in gastric or oesophagogastric junction cancer, patients receiving rilotumumab showed a trend towards improved survival, especially in MET-positive patients, but no clear dose-response relationship was observed. Exposure-response and biomarker analyses were used for dose selection and to differentiate patient subpopulations that may benefit most from treatment. Here, we analyse rilotumumab exposure-survival and exposure-safety and the impact of MET expression on these relationships. METHODS: Individual rilotumumab exposure parameters were generated using population pharmacokinetic modelling. Relationships among rilotumumab dose (7.5 and 15 mg kg(-1)), exposure, and clinical outcomes (progression-free survival (PFS) and overall survival (OS)) were evaluated with Cox regression models and Kaplan-Meier plots. MET status and other baseline covariates were evaluated in subgroup and multivariate analyses. Treatment-emergent adverse events were summarised by exposure. RESULTS: Among MET-positive patients, higher rilotumumab exposure, vs placebo and low exposure, was associated with improved median PFS (80% CI: 7.0 (5.7-9.7) vs 4.4 (2.9-4.9) and 5.5 (4.2-6.8) months) and OS (13.4 (10.6-18.6) vs 5.7 (4.7-10.2) and 8.1 (6.9-11.1) months) without increased toxicity. No rilotumumab benefit was seen among MET-negative patients. CONCLUSIONS: Rilotumumab had an exposure-dependent treatment effect in patients with MET-positive gastric or oesophagogastric junction cancer.

Polymerase chain reaction with single-sided specificity: analysis of T cell receptor delta chain.

In the polymerase chain reaction (PCR), two specific oligonucleotide primers are used to amplify the sequences between them. However, this technique is not suitable for amplifying genes that encode molecules where the 5' portion of the sequences of interest is not known, such as the T cell receptor (TCR) or immunoglobulins. Because of this limitation, a novel technique, anchored polymerase chain reaction (A-PCR), was devised that requires sequence specificity only on the 3' end of the target fragment. It was used to analyze TCR delta chain mRNA's from human peripheral blood gamma delta T cells. Most of these cells had a V delta gene segment not previously described (V delta 3), and the delta chain junctional sequences formed a discrete subpopulation compared with those previously reported.

A consensus primer to amplify both alpha and beta chains of the human T cell receptor.

The use of reverse transcriptase in conjunction with the polymerase chain reaction (RT-PCR) has proven invaluable in the analysis of the T cell receptor (TCR) repertoire of different populations of T cells. However, the presence of a variable region in the T cell receptor has hindered the design of primers for the 5' end of the TCR cDNA. We describe the design and use of a degenerate consensus primer that allows amplification of both the alpha and beta chains of the human TCR. We have used this primer in the analysis of the TCR distribution of T cell clones, peripheral blood lymphocytes and lymphocytes residing in tissue. In addition, the primer has allowed the identification of an alternative splice site in the beta chain constant region which cannot translate into a functional constant region. We have found the primer to be easy to use, sensitive and specific.

Increased expression of interleukin-8 mRNA in ulcerative colitis and Crohn's disease mucosa and epithelial cells.

: Interleukin-8 (IL-8) is a chemotactic cytokine (chemokine), which both attracts and activates granulocytes. IL-8 could have a central function in the initiation and perpetuation of the inflammatory bowel diseases (IBD), due to its relative resistance to inactivation and long half-life in vivo. Using a quantitative reverse transcriptase polymerase chain reaction (RT-PCR) assay, we have observed elevated levels of IL-8 mRNA in colonic mucosal sections obtained from surgically resected specimens from ulcerative colitis (UC) and Crohn's disease (CD) patients with actively inflamed mucosa. The level of IL-8 mRNA expression in the intestinal mucosal biopsies from UC and CD patients was much greater in involved as opposed to noninvolved mucosal sections. The highest expression of IL-8 mRNA detected by RT-PCR was in UC mucosa and in isolated intestinal epithelial cells from UC patients. Increased IL-8 production by cells in IBD intestinal mucosa as well as IBD epithelial cells may be involved in the continuous attraction and activation of granulocytes in the inflamed intestine in both UC and CD patients. Chemokines, such as IL-8, are potent chemoattractant molecules and may have a central role in the augmentation and perpetuation of inflammation in IBD.

Stem cell transplantation for metastatic breast cancer: analysis of tumor contamination.

The purpose of this study was to determine the efficacy, engraftment kinetics, effect of bone marrow tumor contamination, and safety of high-dose therapy and granulocyte-colony stimulating factor (G-CSF) mobilized peripheral blood progenitor cell (PBPC) support for patients with responding metastatic breast cancer. Forty two patients underwent G-CSF (10 microg/kg) stimulated PBPC harvest. PBPC and bone marrow aspirates were analyzed by histologic and immunocytochemical methods for tumor contamination. Thirty-seven patients received high-dose therapy consisting of cyclophosphamide 6 g/m2, thiotepa 500 mg/m2, and carboplatin 800 mg/m2 (CTCb) given as an infusion over 4 d followed by PBPC reinfusion and G-CSF (5 microg/kg) support. No transplant related deaths or grade 4 toxicity was recorded. CD34+ cells/kg infused was predictive of neutrophil and platelet recovery. With a median follow-up of 38 months, three year survival was 44% with relapse-free survival of 19%. Histological bone marrow involvement, found in 10 patients, was a negative prognostic factor and was associated with a median relapse-free survival of 3.5 months. Tumor contamination of PBPC by immunohistochemical staining was present in 22.5% of patients and found not to be correlated with decreased survival. G-CSF stimulated PBPC collection followed by a single course of high dose chemotherapy and stem cell infusion with G-CSF stimulated marrow recovery leads to rapid, reliable engraftment with low toxicity and promising outcome in women with responding metastatic breast cancer.

Evidence for transposition of dispersed repetitive DNA families in yeast.

Dispersed repetitive DNA sequences from yeast (Saccharomyces cerevisiae) nuclear DNA have been isolated as molecular hybrids in lambdagt. Related S. cerevisiae strains show marked alterations in the size of the restriction fragments containing these repetitive DNAs. "Ty1" is one such family of repeated sequences in yeast and consists of a 5.6 kilobase (kb) sequence including a noninverted 0.25 kb sequence of another repetitious family, "delta", on each end. There are about 35 copies of Ty1 and at least 100 copies of delta (not always associated with Ty1) in the haploid genome. A few Ty1 elements are tandem and/or circular, but most are disperse and show (along with delta) some sequence divergence between repeat units. Sequence alterations involving Ty1 elements have been found during the continual propagation of a single yeast clone over the course of a month. One region with a large number of delta sequences (SUP4) also shows a high frequency of sequence alterations when different strains are compared. One of the differences between two such strains involves the presence or absence of a Ty1 element. The novel joint is at one inverted pair of delta sequences.

RNA from the yeast transposable element Ty1 has both ends in the direct repeats, a structure similar to retrovirus RNA.

The RNA homologous to the yeast transposable element Ty1 is one of the more abundant poly(A)+ RNAs in many strains of the yeast Saccharomyces cerevisiae. The 5' and 3' ends of Ty1 RNA have been determined from analysis of cDNA. The 5' end is 245 bases into the left delta sequence measured from the left side of the Ty1 element. The delta sequence is a direct repeat of about 340 base pairs present at each end of the Ty1 element. The Ty1 transcription includes 93-97 bases of the left delta sequence and continues through the entire internal portion of the element and through about 295 bases of the right delta sequence before reaching the 3' end located 38-46 bases from the right side of the right delta sequence. Because the delta sequences present at each end of a single Ty1 element have identical or very similar DNA sequences, these end points for Ty1 RNA raise several questions about the expression of Ty1 elements. First, what are the initiation and termination signals, because the Ty1 transcript must read through a DNA sequence that is identical to the 3' end at about 50 bases from the 5' end? Second, why is the direction of transcription of the Ty1 element opposite to that of genes that are overexpressed after the insertion of a Ty1 element? Third, because the Ty1 RNA itself has direct repeats of about 45 bases, a structure analogous to retrovirus RNAs, is the Ty1 RNA an intermediate in the transposition of Ty1?

A mathematical approach to the analysis of diversity in antibody gene families.

In this article, we develop a mathematical approach for the analysis of diversity in antibody gene families. This approach is arrived at by examing two general questions about protein populations: (1) What is a relative measure of the diversity exhibited by one protein family when compared with a second? (2) What is the probability that two protein populations were derived from a single common population? These quantitative approaches permit a variety of precise evolutionary, genetic, and developmental questions to be asked of antibody gene families. Using this methodology, we demonstrate that the diversity in mouse K-immunoglobulin chains is considerably greater than in their human K counterparts. We also show that the variable (Vl) regions of light chains associated with IgG and IgA immunoglobulins in the mouse appear to have been derived from a common population of Vl genes. This approach also can be used to analyse sequence data from other informational multigene families.

Human T-cell-receptor delta chain: genomic organization, diversity, and expression in populations of cells.

The locus of the delta chain of the human T-cell receptor has been isolated and examined. Three D (diversity) regions and two J (joining) regions are present on the 5' side of the C (constant) region. The closest V (variable) region to the constant region is V delta 2, which in the germ line is found on the 3' side of the constant region in an inverted direction. The genomic structure of the human locus closely parallels its mouse counterpart. Several cDNA sequences and a series of rearranged genomic sequences are compared which demonstrate an enormous potential diversity in the junctional region, between the variable region and the joining region. We find the predominant utilization of the PEER variable region in thymic polyclonal gamma delta cell lines and in some peripheral blood gamma delta cell lines. Thus, the delta chain may have relatively limited variable-region diversity but a large junctional-region diversity. The implications of this observation are discussed.

Gene transfer studies of T cell receptor-gamma delta recognition. Specificity for staphylococcal enterotoxin A is conveyed by V gamma 9 alone.

gamma delta T cells bearing the V gamma 9 gene segment have been shown to recognize staphylococcal enterotoxin A (SEA) and a range of other Ags including mycobacterial Ags. We have established an experimental system to analyze the recognition properties of human TCR-gamma delta on a molecular level by transferring the receptor from its original T cell into a Jurkat T cell host that does not express an endogenous TCR. Three groups of transfectants that express the same delta-chain, V delta 1, but different gamma-chains (V gamma 9-J2-C gamma 2, V gamma 3-J2-C gamma 2, and V gamma 9-JP-C gamma 1) together with the endogenous CD3 were obtained. The transfectant T cells each expressing different gamma delta receptors all produced IL-2 after stimulation with plastic bound anti-CD3 Ab, but only those expressing V gamma 9 responded to stimulation with SEA in the presence of an autologous lymphoblastoid B cell line. In addition, transfectants that expressed V delta 2 combined with V gamma 9 could also respond to SEA. These results indicate that the V gamma 9 portion of the receptor, independent of the J region and C region or the delta-chain, is responsible for recognizing SEA.

Monocyte-chemoattractant protein 1 gene expression in intestinal epithelial cells and inflammatory bowel disease mucosa.

BACKGROUND: Monocyte-chemoattractant protein 1 (MCP-1) activates macrophages and increases the migration of monocytes into tissue during inflammation. It was hypothesized that MCP-1 expression is involved in intestinal inflammation. METHODS: MCP-1 protein was detected by immunohistochemistry and immunoprecipitation. Biological activity of MCP-1 was assessed using a chemotactic assay. MCP-1 messenger RNA (mRNA) levels were measured by quantitative reverse-transcription polymerase chain reaction. RESULTS: In normal mucosa, MCP-1 was predominantly present in surface epithelium. In contrast, inflamed mucosa from patients with ulcerative colitis or Crohn's disease contained multiple cells immunoreactive for MCP-1, including spindle cells, mononuclear cells, and endothelial cells. Furthermore, MCP-1 mRNA expression was markedly increased in inflamed intestinal biopsy specimens from patients with inflammatory bowel disease. MCP-1 was detected in isolated intestinal epithelial cells and in conditioned media from Caco-2 cells. Caco-2 cell-conditioned media stimulated monocyte chemotaxis activity that was inhibited by anti-MCP-1 antibodies. Constituitive MCP-1 mRNA levels in Caco-2 cells were up-regulated by interleukin 1 beta and down-regulated by dexamethasone. CONCLUSIONS: In addition to lamina propria macrophages, endothelial cells, and spindle cells, intestinal epithelial cells are able to produce MCP-1. MCP-1 is expressed constitutively in the intestinal colonic mucosa and is up-regulated during inflammation.

Identification and sequence of a fourth human T cell antigen receptor chain.

Thymus-derived lymphocytes (T cells) use clonally distributed antigen receptors to recognize peptide fragments associated with products of the major histocompatibility complex (MHC) (refs 1-4). On most murine and human T cells the T cell receptor (TCR) is composed of disulphide-linked alpha and beta chains (TCR alpha/beta), each of which contains constant and variable domains, and which are associated with the invariant chains of the CD3 complex. It has been demonstrated, however, that a distinct CD3-associated TCR is expressed on a small subset of T cells or immature thymocytes which fail to express either CD4 or CD8 (refs 7-14), the molecules associated with class II or class I MHC antigen recognition. Instead of TCR alpha/beta, these cells express heterodimers of gamma and delta chains (TRC gamma/delta). The genes encoding alpha, beta, and gamma have been isolated and characterized. A new murine T cell receptor (Cx) gene which undergoes rearrangement and expression early during T cell ontogeny has recently been identified 5' of the murine J alpha C alpha gene locus. Here we isolate and sequence the homologous transcript from PEER, a human cell line that expresses a TCR gamma/delta, and show that it encodes a protein with characteristic V, D, J, and C segments. Using probes derived from this transcript, we have shown that both PEER and MOLT-13, another TCR gamma/delta-expressing cell line, rearrange this locus and express two sizes of transcripts differing in the 3' untranslated region. Using a synthetic peptide derived from the deduced C region sequence, we have prepared antisera that precipitates the delta chain of the TCR from both PEER and MOLT-13, thus demonstrating that Cx and its human homologue code for the delta chain of the TCR.