ImmTAC-redirected tumour cell killing induces and potentiates antigen cross-presentation by dendritic cells

Antigen cross-presentation by dendritic cells (DCs) is thought to play a critical role in driving a polyclonal and durable T cell response against cancer. It follows, therefore, that the capacity of emerging immunotherapeutic agents to orchestrate tumour eradication may depend on their ability to induce antigen cross-presentation. ImmTACs [immune-mobilising monoclonal TCRs (T cell receptors) against cancer] are a new class of soluble bi-specific anti-cancer agents that combine pico-molar affinity TCR-based antigen recognition with T cell activation via a CD3-specific antibody fragment. ImmTACs specifically recognise human leucocyte antigen (HLA)-restricted tumour-associated antigens, presented by cancer cells, leading to T cell redirection and a potent anti-tumour response. Using an ImmTAC specific for a HLA-A*02-restricted peptide derived from the melanoma antigen gp100 (termed IMCgp100), we here observe that ImmTAC-driven melanoma-cell death leads to cross-presentation of melanoma antigens by DCs. These, in turn, can activate both melanoma-specific T cells and polyclonal T cells redirected by IMCgp100. Moreover, activation of melanoma-specific T cells by cross-presenting DCs is enhanced in the presence of IMCgp100; a feature that serves to increase the prospect of breaking tolerance in the tumour microenvironment. The mechanism of DC cross-presentation occurs via 'cross-dressing' which involves the rapid and direct capture by DCs of membrane fragments from dying tumour cells. DC cross-presentation of gp100-peptide-HLA complexes was visualised and quantified using a fluorescently labelled soluble TCR. These data demonstrate how ImmTACs engage with the innate and adaptive components of the immune system enhancing the prospect of mediating an effective and durable anti-tumour response in patients.

Abstract 3528: IMCmage1: A novel bi-specific biologic re-directing T cells to kill MAGE-A3/A6 presenting cancers

In a minority of cancer patients immunotherapy has shown the capacity to eradicate tumours leading to clinical remission and the promise of a cure. In the majority of patients however, a cure remains elusive due to active immune evasion by cancers; HLA-down-regulation and immunosuppression are two of the known mechanisms adopted by cancers to promote their survival and proliferation. To overcome these challenges we have developed bi-specific soluble biologics termed ImmTACs (Immune mobilising mTCR against cancer) to re-direct the immune system to recognise and kill cancers. Antigenic peptide fragments presented by HLA molecules on the surface of cancer cells constitute the largest class of cancer associated targets. T cells scan the HLA-peptide (pHLA) antigens being presented to them; sufficient recognition by the harboured T Cell Receptor (TCR) will result in T cell activation and killing of the antigen presenting cell. In cancer patients this process is inefficient partly due to the low affinity TCRs expressed by tumour specific T cells and the low abundance of pHLA on cancers. ImmTACs comprise a soluble TCR with an enhanced affinity for cancer associated pHLA (targeting end) fused to an anti-CD3 scfv, enabling potent T cell re-direction (effector end). Our pipeline constitutes a number of ImmTACs targeting various antigen pHLA complexes relevant to numerous cancer indications. IMCmage1 is a novel ImmTAC targeting MAGE-A3168-176 in the context of HLA-A1. MAGE-A3 is a well validated cancer testis antigen expressed in a variety of cancers including myeloma, NSCLC, prostate cancer, melanoma, bladder cancer, oesophageal cancer and others. IMCmage1 re-directs T cells from cancer patients or healthy donors to kill a range of MAGE positive cell-lines in vitro; this activity is observed against cells presenting as few as 40 epitopes per cell and is coupled with the release of pro-inflammatory cytokines including IFNα, TNFα, IL-2, MIP1α and others. We also demonstrate that IMCmage1 specifically targets and kills the myeloma associated population within CD138+ cells extracted from the marrow of a stage III myeloma patient. IMCmage1 specificity was confirmed by exposure to a panel of HLA-A1 MAGE negative primary cells derived from various organs such as the heart, skin, lung and others; no significant activity was detected. A phase I clinical trial in multiple myeloma to assess tolerability and establish a maximum tolerated dose is planned to commence in Q2 2012.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 3528. doi:1538-7445.AM2012-3528

Gene expression profiling in male genital lichen sclerosus

Male genital lichen sclerosus (MGLSc) has a bimodal distribution in boys and men. It is associated with squamous cell carcinoma (SCC). The pathogenesis of MGLSc is unknown. HPV and autoimmune mechanisms have been mooted. Anti extracellular matrix protein (ECM)1 antibodies have been identified in women with GLSc. The gene expression pattern of LSc is unknown. Using DNA microarrays we studied differences in gene expression in healthy and diseased prepuces obtained at circumcision in adult males with MGLSc (n = 4), paediatric LSc (n = 2) and normal healthy paediatric foreskin (n = 4). In adult samples 51 genes with significantly increased expression and 87 genes with significantly reduced expression were identified; paediatric samples revealed 190 genes with significantly increased expression and 148 genes with significantly reduced expression. Concordance of expression profiles between adult and paediatric samples indicates the same disease process. Functional analysis revealed increased expression in the adult and child MGSLc samples in the immune response/cellular defence gene ontology (GO) category and reduced expression in other categories including genes related to squamous cancer. No specific HPV, autoimmune or squamous carcinogenesis-associated gene expression patterns were found. ECM1 and CABLES1 expression were significantly reduced in paediatric and adult samples respectively.

Bi-specific TCR anti-CD3 fusion for the immunotherapy of malignant melanoma (156.16)

The human immune system can theoretically identify malignant cells by ‘scanning’ peptide antigens presented on the cell surface by Class I HLA molecules, and indeed many cancer patients generate CD8 cyto-toxic T cell responses to tumour-specific antigens. However, the majority of patients fail to clear tumours, since T cell avidity for self-antigens tends to be weak, and cancer cells employ escape mechanisms for avoiding destruction by T cells. We have engineered novel, bi-functional protein therapeutics termed ImmTACs which re-direct the immune system to target and destroy tumour cells with a high degree of potency and specificity. IMCgp100 comprises a soluble, high affinity T cell Receptor specific for the HLA-A2 presented melanoma-associated epitope gp100 280-288, fused to an anti-CD3 scFv domain. The anti-CD3 moiety activates a polyclonal T cell response when targeted to melanoma cells presenting as few as twenty gp100 epitopes, predominantly through activation of effector memory CD8 lymphocytes, leading to killing of the tumour cells. Extensive in vitro testing of IMCgp100 with a panel of tumour cells and normal human tissue cells demonstrates pico-Molar potency against cancer cells and specificity for HLA-A2 gp100 positive cells. The agent is able to inhibit tumour growth in mouse xenograft models. A phase I dose-escalation trial in late stage melanoma patients was initiated in October 2010 and interim results will be presented at this meeting.

Facteurs du choix de la voie d’abord des hystérectomies pour lésions utérines bénignes (prolapsus et indications obstétricales exclus)

OBJECTIVES

We searched for the factors determining the type of hysterectomy (vaginal, laparoscopy or laparotomy) performed in women with supposedly benign uterine disease.

MATERIAL AND METHOD

We conducted a retrospective study of 101 consecutive hysterectomies performed on voluminous uteruses, prolapsus and obstetrical indications excluded. The following factors likely to have influenced the decisions were examined: patient age, nulliparity, menopausal status, history of laparotomy, uterus weight, narrow vagina, nature of uterus lesions, associated unilateral or bilateral annexectomy, complications.

RESULTS

The frequencies were: vaginal route 58.4% (average uterine weight 249.4 g, range 93-1149 g), laparoscopic preparation 37.6% (average uterine weight 348 g, range 92-818 g), and laparotomy 4% (average uterine weight 586.2 g, range 112-1216 g). Factors determining type of hysterectomy were uterine weight (and therefore volume) (p < 0.05), nulliparity (p < 0.04), narrow vagina probed by compulsory Schuchardt incision (p < 0.02), associated annexectomy (p < 0.01). No other factors were significantly determinant. The vaginal route appears to be highly preferred.

CONCLUSION

Vaginal hysterectomy is clearly the most preferred and practiced. Laparoscopy may be helpful for vaginal hysterectomy and laparotomy is exceptional.

LAG-3 (CD223) reduces macrophage and dendritic cell differentiation from monocyte precursors

Major histocompatibility complex (MHC) class II molecules expressed on monocytes may play a role in the control of differentiation of antigen-presenting cells. A soluble LAG-3 (CD223) molecule (sLAG-3) is a natural, high-affinity ligand for MHC class II. It is known to induce maturation of monocyte-derived dendritic cells in vitro and is used as a vaccine adjuvant to induce CD4 T helper type 1 responses and CD8 T-cell responses in vivo. Here, we demonstrate that sLAG-3 (but not an MHC class II-specific monoclonal antibody) reduces the differentiation of monocytes into macrophages in the presence of granulocyte-macrophage colony-stimulating factor (GM-CSF) as well as their differentiation into dendritic cells in the presence of GM-CSF and interleukin-4, as shown by a decrease in CD14 and CD1a expression, respectively. Dendritic cells derived from monocytes in the presence of sLAG-3 showed impaired antigen-presentation function, as assessed by the reduced capability to induce proliferation of T cells. Our results suggest that activated LAG-3(+) lymphocytes present at sites of inflammation may reduce the differentiation of monocytes into macrophages or fully competent antigen-presenting dendritic cells, thus limiting the magnitude of the ongoing T-cell immune responses.

Targeting of the dual oxidase 2 N-terminal region to the plasma membrane

Dual oxidase 2 (Duox2) is a cell surface glycoprotein that probably provides thyroperoxidase with the H2O2 required to catalyze thyroid hormone synthesis. No functional H2O2-generating system has yet been obtained after transfecting Duox2 into non-thyroid cell lines, because it is retained in the endoplasmic reticulum (ER). We investigated the level of maturation of various Duox2 truncated proteins in an attempt to identify the region of Duox2 responsible for its remaining in the ER. Duox2-Q686X mutant, corresponding to the N-terminal ectodomain including the first putative transmembrane domain, was expressed in different cell lines. Carbohydrate content analysis revealed that complex type-specific Golgi apparatus (GA) oligosaccharides were present on pig Duox2-Q686X, whereas human truncated Duox2 carried only high mannose-type sugar chains characteristic of the ER. Further characterization using surface biotinylation and flow cytometry assays indicated that pig Duox2-Q686X was present at the plasma membrane, whereas human Duox2-Q686X remained inside the cell. The replacement of the last 90 residues of the human Duox2-Q686X with the pig equivalent region allowed the chimerical peptide to reach the Golgi apparatus. Pig mutants containing the complete first intracellular loop with or without the second transmembrane domain accumulated in the ER. These findings show that 1) the human Duox2-Q686X region encompassing residues 596-685 prevents mutant exportation from the ER and 2) there is a pig Duox2 retention domain in the first intracellular loop. In addition, missense mutations of four cysteines (Cys-351, -370, -568, or -582) completely inhibited the emergence of pig Duox2-Q686X from the ER compartment, indicating their importance in Duox2 maturation.

MHC class II signal transduction in human dendritic cells induced by a natural ligand, the LAG-3 protein (CD223)

On encountering a danger signal, dendritic cells (DCs) undergo a complex maturation process and become specialized in antigen presentation. We previously reported that engagement of major histocompatibility complex (MHC) class II molecules located on immature DCs in membrane rafts by lymphocyte activation gene-3 (LAG-3; CD223) leads to DC maturation. In contrast, exposure of DCs to class II-specific monoclonal antibodies (mAbs) did not lead to maturation. Here, we have investigated the signal transduction pathways involved in the LAG-3-induced maturation of human monocyte-derived DCs. We first show that areas of raft aggregation (both cholesterol rich and CDw78 microdomains) could be visualized using a soluble LAG-3 protein and confocal microscopy. Engagement of class II molecules by both its natural ligand LAG-3 and class II mAb induces rapid protein phosphorylation of phospholipase Cgamma2 (PLCgamma2) and p72syk as well as activation of phosphatidyl inositol 3-kinase/Akt, p42/44 extracellular signal-regulated protein kinase, and p38 mitogen-activated protein kinase pathways. Studies using inhibitors demonstrate that these 3 pathways are all important in inducing the maturation process of LAG-3-stimulated DCs. When class II molecules were ligated with LAG-3 versus specific antibody, differences in the phosphorylation pattern of c-Akt were observed. Thus, MHC class II signaling in DCs involves several pathways that have to be finely regulated to lead to cell activation and maturation.

MHC class II engagement by its ligand LAG-3 (CD223) leads to a distinct pattern of chemokine and chemokine receptor expression by human dendritic cells

Upon stimulation by infectious agent products, dendritic cells (DC) become activated, express high levels of class I and class II antigens, CD80, CD86 and CD83 and migrate to secondary lymphoid organs where they can prime naive CD4-helper and CD8-cytotoxic T-cells. Cognate CD4(+) T-cell help mediated by CD40L along with DC stimulation with another T-cell effector molecule, termed lymphocyte activated gene-3 (LAG-3 or CD223, a ligand for MHC class II) have been shown to induce this maturation process. Both CD40L and LAG-3 have been used as vaccine adjuvants to induce CTL and CD4 Th1 responses. Here, we studied the effect of a soluble LAG-3Ig molecule on the chemokine and chemokine receptor profile of human immature monocyte-derived DC. LAG-3Ig, unlike CD40L, induced an inflammatory signal in terms of IL-8 and MIP-1alpha/CCL3 production and, in contrast to LPS, induced production of chemokines (MDC/CCL22 and TARC/CCL17) known to direct the migration of maturing DC to lymph nodes. In LAG-3-matured DC, surface expression of CCR5 (a receptor for MIP-1alpha/CCL3) was down-regulated and CCR7 (a receptor for MIP-3beta and SLC) was up-regulated. However, LAG-3-matured, but not LPS- or CD40L-matured DC retained their capacity to migrate in chemotaxis chambers and to respond to MIP-1alpha. Altogether, these data represent the first evidence that MHC class II signaling may affect DC migration to secondary lymphoid tissues.

Acrolein toxicity: comparative in vitro study with lung slices and pneumocytes type II cell line from rats

Toxicological effects of acrolein have been studied in precision-cut rat lung slices and in L2 cells, a rat pneumocyte II cell line. These two models were cultured for 24 h with or without acrolein (0-100 microM in L2 cells; 0-200 microM in lung slices). Treatment with this pneumotoxicant produced a concentration dependent decrease in intracellular ATP levels. Acrolein concentrations higher than 50 microM induced ATP decrease in slices, while this decrease occurred from 10 microM acrolein in L2 cells. Detoxification marker evaluations showed that mostly the glutathione pathway was altered after acrolein treatment in both models. Intracellular glutathione (GSH) levels were drastically increased with an acrolein concentration of 10 microM. This increase was concomitant with glutathione-S-transferase (GST) and glutathione reductase (GRED) activities in L2 cells. After this strong increase, these enzymatic activities as well as GSH levels were quickly decreased. In precision-cut rat lung slices, the induction of the glutathione pathway was less clear-cut. A bell-shaped dose response curve was observed with a maximum for 5 microM acrolein for GST and GRED activities. These differences between acrolein toxic ranges could be explained by the presence of an active detoxification pathway in slices compared to its relative lack in L2 cells.

Endocrine and hemodynamic responses to dopamine infusion in the guinea-pig: effects of ACE inhibition with perindopril

The effects of dopamine on plasma renin-angiotensin-aldosterone system vasopressin levels and blood pressure were studied in anesthetized guinea-pig. The inhibition of the angiotensin converting enzyme with perindopril permitted assessment of the role of the renin-angiotensin system. In perindopril-treated guinea-pigs, the activity of angiotensin-converting enzyme was decreased by 90% with simultaneous increases in plasma renin activity and angiotensin I concentration; aldosterone and vasopressin levels, blood pressure and heart rate were not modified. Dopamine depressed mean arterial pressure by 30% and increased heart rate (8%) in controls. Dopamine infusion did not affect either plasma renin activity or angiotensin I concentration or angiotensin-converting enzyme activity in control animals. But in perindopril pretreated animals it further increased plasma renin activity (88%) and angiotensin I concentration (35%). Finally, in controls, dopamine infusion increased plasma vasopressin concentrations (91%) whereas this increase did not occur in perindopril treated animals.

Cardiovascular and hormonal responses to ANP infusion in the guinea-pig: effects of angiotensin-converting enzyme inhibition with perindopril

In the guinea-pig, perindopril inhibited plasma angiotensin converting enzyme (ACE) by 90% when given orally at 2 mg/kg/day during 10 days. Mean blood pressure and plasma aldosterone, cortisol and vasopressin concentrations were not modified by this treatment, while plasma renin activity (PRA) and plasma angiotensin I concentrations increased significantly. The same parameters were studied using a constant intravenous 30 min-infusion of atrial natriuretic peptide (ANP) (0.1 micrograms.kg-1min-1). This dose of ANP infused to anesthetized guinea-pigs induced a significant decrease in mean blood pressure (about -20%) in control and in perindopril treated animals. In ANP infused animals, plasma aldosterone and cortisol concentrations decreased similarly in both groups by about -50%, whereas plasma vasopressin concentrations increased in controls (+169%) but not in perindopril treated guinea-pigs. An increase in PRA and plasma angiotensin I concentrations was observed in both groups after the infusion of ANP. Thus, when ANP demonstrated an potent hypotensive effect a concomitant increase in PRA occurred. The rise observed in vasopressin concentration in control animals was probably mediated by angiotensin II. The fall in plasma aldosterone and cortisol concentrations observed after ANP infusion demonstrated a direct potent action of ANP at the adrenal levels.

Lack of effect of perindopril on plasma and adrenal corticosteroids in the guinea pig during the estrous cycle and under contraceptive treatment

We studied changes in cortisol, aldosterone, progesterone, estrogens and cholesterol in cyclic female guinea-pigs and in animals under contraceptive, treated or not with an inhibitor of angiotensin converting enzyme (ACE): perindopril. Perindopril decreased ACE by 80% without affecting steroid profiles. Peak value for plasma progesterone occurred at meta-estrus and diestrus. It disappeared under contraceptive treatment. The very low levels of estrogens in the female guinea pig remained unchanged in all cases. Plasma cortisol concentrations were higher at pro-estrus and estrus whereas plasma aldosterone concentrations remained constant during the estrous cycle and under contraceptive treatment. Furthermore, aldosterone did not change under perindopril treatment despite the decrease of the activity of ACE. The contraceptive treatment decreased plasma cholesterol levels. Under perindopril treatment, this drop was amplified. No change was detected in adrenal steroid concentrations, except for progesterone which decreased under contraceptive treatment.

Muscarinic receptors of the albino rabbit ciliary process

Muscarinic receptor binding sites were identified in membranes prepared from albino rabbit ciliary processes, using the muscarinic antagonist [3H]L-quinuclidinyl benzylate as the radioligand. Analysis of saturation binding experiments demonstrated that [3H]L-quinuclidinyl benzylate bound to an apparent homogeneous population of binding sites with a Kd value of 6.4 pm and a Bmax value of 155 fmol mg-1 protein. Seventy percent (70%) of binding sites showed high affinity for pirenzepine, i.e. belonged to the M1 subtype. In contrast, AF-DX 116 was unable to discriminate between subtypes of muscarinic binding sites in this tissue. Carbachol caused a dose-dependent increase in phosphatidylinositol turnover (EC50 = 154 microM) in ciliary processes. A maximum stimulation of 652% of basal activity was obtained following a 45 min incubation with 10 mM carbachol. The potency of muscarinic antagonists to block the carbachol-induced response was comparable to that found for M1 receptors in other tissues. Oxotremorine and pilocarpine behaved like partial agonists in this assay. The carbachol-induced increase in phosphatidylinositol turnover was also observed in a suspension of epithelial cells from ciliary processes and it was blocked by atropine; thus, indicating the presence of muscarinic receptors functionally coupled to phosphatidylinositol turnover in these cells.

Alpha 1-adrenoceptors in the albino rabbit ciliary process

3H-Prazosin and 3H-rauwolscine binding sites were identified in a membrane suspension prepared from albino rabbit iris + ciliary body. Scatchard analysis of saturation binding experiments demonstrated that both 3H-prazosin and 3H-rauwolscine bind to a single population of binding sites with KD values of 0.87 nM and 5.33 nM, respectively. Bmax values of 65.7 and 198 fmol/mg protein were obtained for 3H-prazosin and 3H-rauwolscine, respectively. Displacement studies by several adrenergic agonists and antagonists indicated that 3H-prazosin and 3H-rauwolscine labelled alpha 1- and alpha 2-adrenoceptors, respectively, in the iris + ciliary body. Epinephrine, norepinephrine and phenylephrine were able to stimulate the synthesis of 3H-inositol phosphates in ciliary processes labelled with 3H-inositol, with EC50 values of 2.4, 12 and 10 microM, respectively. The corresponding maximum stimulations of basal activity were 433, 430 and 283%, respectively. Phenylephrine behaved like a partial agonist in this assay. The norepinephrine response could be potently antagonized by prazosin (Ki = 27 nM), with rauwolscine being 285-fold less potent. An epithelial cell suspension was prepared from the ciliary process. Stimulation of phosphatidylinositol turnover by norepinephrine (0.1 mM) was observed, and this could be blocked by prazosin (10 microM), thus, indicating the presence of alpha 1-adrenoceptors, coupled to phosphatidylinositol turnover, in epithelial cells of the rabbit ciliary process.