Abstract 2490: CD40 ligand expressing recombinant vaccinia virus (rVV40L) modulation of central memory CD8-mediated immune response

In cancer immunotherapy, induction of tumor-reactive CD8+ T cells displaying phenotypic and functional profile of central memory T cells (TCM) is associated with favorable prognosis. A key element in the generation of TCM CD8+ cells is represented by the help provided by CD4+ T cells during the priming of naïve CD8+ T cells. In particular CD40 ligand (CD40L) expressed and/or secreted by activated CD4+ T cells triggers CD40 receptor expressed on antigen presenting cells (APCs) thereby enhancing their antigen presentation capacity. In order to bypass the requirement of CD4+ T cells we generated a non-replicating recombinant vaccinia virus encoding human CD40L (rVV40L) and compared its ability to shape CD8-mediated immune response to soluble CD40L recombinant protein (sCD40L).

In this regard, our data clearly underline the different biological properties of membrane-bound CD40L, as provided by rVV40L infection, as compared to its soluble form, in CD14+ APCs activation. Notably, considering expression of IL-12p40, IFN-a and -b genes, cytokines of proven relevance for memory T cell induction, rVV40L-infection was much more potent than s40L-treatment alone or combine with WT infection. In parallel, s40L-stimulation induced a much more significant expression of IL-10 and indoleamine-2, 3-dioxygenase (IDO) genes encoding immunosuppressive factors. Considering a panel of molecules involved in the generation of the immunological synapse with T cells on CD14+ cells, rVV40L appeared to promote a less intense up regulation of CD80 co-stimulatory molecules but, most importantly, only a minor increase of programmed death ligand-1 (PD-L1). Therefore, gene expression and phenotypic profiles suggested that rVV40L-infected CD14+ cells might be highly effective APC in the induction of TCM CD8+ cells. Indeed, a single in vitro stimulation of naïve CD8+ T cells by rVV40L-infected CD14+ cells, in the absence of CD4+ T cells, was able to promote the rapid generation of central memory TAA (MAGE and MART-1) specific CD8+ T cells. These TCM were characterized by the typical central memory phenotype, as indicated by co-expression of CD45RO, CD62L and IL-7Ra, and by the high proliferative potential upon antigen recognition.

Collectively our data indicate that rVV40L efficiently modulates the quality of different APC signals delivered during the formation of the immunological synapse with CD8+ T cells. These in-vitro observations validate the strong clinical potential of our recombinant vaccinia virus constructs co-expressing CD40L for cancer immunotherapies.

Citation Format: Emanuele Trella, Evangelos Panopoulos, Nermin Raafat, Chantal Mengus, Emmanuel Traunecker, Swantje Heidtmann, Michael Heberer, Daniel Oertli, Giulio Cesare Spagnoli, Paul Zajac. CD40 ligand expressing recombinant vaccinia virus (rVV40L) modulation of central memory CD8-mediated immune response. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2490. doi:10.1158/1538-7445.AM2015-2490

Bioreactor-engineered cancer tissue-like structures mimic phenotypes, gene expression profiles and drug resistance patterns observed "in vivo"

Anticancer compound screening on 2D cell cultures poorly predicts "in vivo" performance, while conventional 3D culture systems are usually characterized by limited cell proliferation, failing to produce tissue-like-structures (TLS) suitable for drug testing. We addressed engineering of TLS by culturing cancer cells in porous scaffolds under perfusion flow. Colorectal cancer (CRC) HT-29 cells were cultured in 2D, on collagen sponges in static conditions or in perfused bioreactors, or injected subcutaneously in immunodeficient mice. Perfused 3D (p3D) cultures resulted in significantly higher (p < 0.0001) cell proliferation than static 3D (s3D) cultures and yielded more homogeneous TLS, with morphology and phenotypes similar to xenografts. Transcriptome analysis revealed a high correlation between xenografts and p3D cultures, particularly for gene clusters regulating apoptotic processes and response to hypoxia. Treatment with 5-Fluorouracil (5-FU), a frequently used but often clinically ineffective chemotherapy drug, induced apoptosis, down-regulation of anti-apoptotic genes (BCL-2, TRAF1, and c-FLIP) and decreased cell numbers in 2D, but only "nucleolar stress" in p3D and xenografts. Conversely, BCL-2 inhibitor ABT-199 induced cytotoxic effects in p3D but not in 2D cultures. Our findings advocate the importance of perfusion flow in 3D cultures of tumor cells to efficiently mimic functional features observed "in vivo" and to test anticancer compounds.

Abstract 2024: Resistance of colorectal cancer cells to 5-FU treatment in three dimensional cell culture models under perfusion involves BCL-2

Assessment of the effectiveness of chemotherapeutic compounds in bidimensional cell cultures poorly mimics resistance development and the tumor-microenvironment complexity in vivo. In this study we addressed the suitability of a perfused bioreactor to sustain colorectal cancer cell growth and to test established treatment regimens in an in-vitro setting as compared to normal cell culture or xenografts of the same cell line.

By culturing the HT29 colorectal cancer cell line in 3D on collagen scaffolds tissue-like structures characterized by a heterogeneous pattern of proliferating and apoptotic cells closely resembling xenografts from the same cell line as generated in immunodeficient mice could be successfully established. CDX2, a colorectal cancer tumor-marker , was expressed in 3D static and perfused cultures, but not in 2D cultures. Upon perfusion, homogeneous seeding on scaffolds could be obtained and significantly higher numbers of tumor cells were recovered, as compared to static cultures (13.7 fold increase, p&lt;0.0001).

After 48 hours treatment with clinically relevant concentrations of 5-FU no effect on numbers of cells cultured in 3D under perfusionand as xenografts was observed, as compared to a 55.8% inhibition of 2D cultures. The fraction of Ki67 negative cells (G0 cell phase), was increased after a 48 hours treatment in the 3D perfused and xenografts, but it reached again levels similar to untreated cells after 96 hours. In contrast,cells surviving n 2D cell cultures remained largely positive for Ki67. Importantly, in perfused cultures we could only observe a marginal effect on the expression of BCL-2, TRAF1, FLIP apoptosis resistance genes, as compared to a significant down regulation of their expression in 2D cell cultures and 3D static conditions. In the same line, a combination of ABT-199, a new clinically approved BCL-2 inhibitor, and 5-FU induced additional cytostatic and cytotoxic effects in 3D perfused but not in 2D cell cultures (83.3% inhibition vs. 39.8% p=0.003).

Notably, we found that BCL-2 expression in tissues from neoadjuvant treated patients with resistance to treatment was higher than in stage and grade matched colorectal cancers from untreated patients or patients responding to treatment.

Cultures in perfused bioreactors offer the possibility of generating tumour tissue-like structures over a short time period. These structures are characterized by sensitivity to chemotherapeutic treatments similar to that of xenografted tumors and significantly different from standard 2D cellular assays.In particular, our data suggest that inhibition of BCL-2 in combination with 5-FU treatment in colorectal cancer could be endowed with therapeutic potential.

Citation Format: Christian Hirt, Adam Papadimitropoulos, Evangelos Panopoulos, Valentina Mele, Manuele Muraro, Eleonora Cremonesi, Raoul Droeser, Chantal Mengus, Michael Heberer, Daniel Oertli, Giandomenica Iezzi, Paul Zajac, Serenella Eppenberger-Castori, Luigi Tornillo, Luigi Terracciano, Ivan Martin, Giulio Spagnoli. Resistance of colorectal cancer cells to 5-FU treatment in three dimensional cell culture models under perfusion involves BCL-2. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 2024. doi:10.1158/1538-7445.AM2014-2024

Abstract 2843: Recombinant Vaccinia virus expressing CD40L: a multipotent antitumor immunogenic reagent

Recombinant vaccinia virus (rVV) is one of the most immunogenic viral vectors. Its immunogenicity can be further modulated by the insertion of transgenes or deletion of viral genes which are involved in immune responses or specific cellular pathways. We generated a rVV encoding human CD154 (CD40L) and confirmed an efficient licensing of antigen presenting cells (APC), upon infection with a non-replicating (psoralen UV-inactivated) CD40L-rVV, as demonstrated by increased expression of (i) surface ligand/receptors (MHC I/II, CD80), (ii) Th1 cytokines (IL-12, IL-15, TNFa) and most importantly (iii) an increased capacity to stimulate TAA specific CTL proliferation. The hereby presented results are further characterizing some aspects of the pleiotropic roles in immuno-oncology of CD40 triggering via CD40L expressing recombinant vaccinia virus.

One of the immuno-modulatory functions of CD40L-CD40 is to play a key role during CD8+ priming for the generation of memory responses. Using sorted naive CD8+ Tcells (CD45RA+CD62L+) primed with allogeneic CD14+ infected with rVV 40L we observed an increased central memory phenotype (CD45RO+ CD62L+) as compared to culture primed with wild type virus infected cells. Moreover, rVV-CD40L stimulation of CD14+ cells also led to the inhibition of co-cultured tumor cells’ proliferation, correlating with increased TNFα expression. Finally, apoptosis of CD40+ tumor cell lines was induced upon direct infection with this CD40L non-replicating recombinant virus.

These data are confirming the potent capacities of recombinant vaccinia viruses expressing CD40L to efficiently trigger multiple CD40 mediated anti-tumor pathways. Not only this vector enhances the generation of tumor specific CD8+ T cells effector and memory responses, but it also promotes anti-tumoral functions of innate immune cells and is even able to directly induce apoptosis in CD40+ tumor cells. These in-vitro observations underline the strong clinical potential of recombinant vaccinia virus expressing CD40L in cancer viro- and immunotherapies.

Citation Format: Evangelos Panopoulos, Emanuele Trella, Nermin Raafat, Chantal Mengus, Giulio Spagnoli, Paul Zajac. Recombinant Vaccinia virus expressing CD40L: a multipotent antitumor immunogenic reagent. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2843. doi:10.1158/1538-7445.AM2013-2843

Soluble CD40 ligand as a biomarker for storage-related preanalytic variations of human serum

There are currently no appropriate and sensitive biomarkers available to assess preanalytic variations in human biological fluids stored in biobanks. We identified soluble CD40 ligand (sCD40L) as the first ubiquitous biomarker to show an on-off response in serum exposed to moderate or elevated room temperature conditions. We used immunoenzyme assays to monitor the sCD40L response after 12 h storage at 37 degrees C or 48 h at 20 degrees C. Our findings show that prolonged storage of serum samples at elevated room temperature can be determined by the absence of detectable sCD40L.