Heterologous Prime-Boost Vaccination with a Peptide-Based Vaccine and Viral Vector Reshapes Dendritic Cell, CD4+ and CD8+ T Cell Phenotypes to Improve the Antitumor Therapeutic Effect

Heterologous prime-boost settings with a protein vaccine and the viral vector vesicular stomatitis virus, both expressing tumor-associated antigens (KISIMA-TAA and VSV-GP-TAA), have been previously shown to generate potent antitumor immunity. In the cold TC-1 model (HPV antigen) and the immune-infiltrate MC-38 model (Adpgk, Reps1 and Rpl18 neo-antigens), we further investigated pivotal immune cells that educate CD8+ T cells. Heterologous prime-boost vaccination induced a superior antitumor response characterized by the increase in number and functionality of antigen-specific CD8+ T cells, recruitment of cross-presenting dendritic cells, and polarization of CD4+ T cells towards an antitumor Th1 phenotype within the tumor and tumor-draining lymph nodes, turning the cold TC-1 tumor into a hot, inflamed tumor. In the inflamed MC-38 tumor model, treatment combination markedly prolonged the overall survival of mice. Treatment with multi-epitope vaccines also induced high frequencies of multiple antigen specificities in the periphery and in the tumor. Prime-boost treatment reduced tumor-infiltrating regulatory CD4+ T cells whilst increasing cross-presenting dendritic cells in tumor-draining lymph nodes. In conclusion, heterologous prime-boost vaccination possesses the ability to induce a potent anti-tumor response in both immune-excluded and immune-infiltrated mouse tumor models. Additionally, this study highlights the design of a multi-epitope vaccine for cancer immunotherapy

Targeting self- and neoepitopes with a modular self-adjuvanting cancer vaccine

Induction of a potent CD4 and CD8 T-cell response against tumor-specific and tumor-associated antigen is critical for eliminating tumor cells. Recent vaccination strategies have been hampered by an inefficacious and low amplitude immune response. Here we describe a self-adjuvanted chimeric protein vaccine platform to address these challenges, characterized by a multidomain construction incorporating (i) a cell penetrating peptide (CPP) allowing internalization of several multiantigenic Major Histocompatibility Complex (MHC)-restricted peptides within (ii) the multiantigenic domain (Mad) and (iii) a TLR2/4 agonist domain (TLRag). Functionality of the resulting chimeric protein is based on the combined effect of the above-mentioned three different domains for simultaneous activation of antigen presenting cells and antigen cross-presentation, leading to an efficacious multiantigenic and multiallelic cellular immune response. Helper and cytotoxic T-cell responses were observed against model-, neo- and self-antigens, and were highly potent in several murine tumor models. The safety and the immunogenicity of a human vaccine candidate designed for colorectal cancer treatment was demonstrated in a non-human primate model. This newly engineered therapeutic vaccine approach is promising for the treatment of poorly infiltrated tumors that do not respond to currently marketed immunotherapies

Enhancing Antitumor Immune Responses by Optimized Combinations of Cell-penetrating Peptide-based Vaccines and Adjuvants

Cell penetrating peptides (CPPs) from the protein ZEBRA are promising candidates to exploit in therapeutic cancer vaccines, since they can transport antigenic cargos into dendritic cells and induce tumor-specific T cells. Employing CPPs for a given cancer indication will require engineering to include relevant tumor-associated epitopes, administration with an appropriate adjuvant, and testing for antitumor immunity. We assessed the importance of structural characteristics, efficiency of in vitro transduction of target cells, and choice of adjuvant in inducing the two key elements in antitumor immunity, CD4 and CD8 T cells, as well as control of tumor growth in vivo. Structural characteristics associated with CPP function varied according to CPP truncations and cargo epitope composition, and correlated with in vitro transduction efficiency. However, subsequent in vivo capacity to induce CD4 and CD8 T cells was not always predicted by in vitro results. We determined that the critical parameter for in vivo efficacy using aggressive mouse tumor models was the choice of adjuvant. Optimal pairing of a particular ZEBRA-CPP sequence and antigenic cargo together with adjuvant induced potent antitumor immunity. Our results highlight the irreplaceable role of in vivo testing of novel vaccine constructs together with adjuvants to select combinations for further development.Molecular Therapy (2016); doi:10.1038/mt.2016.134

Identification of VHY/Dusp15 as a Regulator of Oligodendrocyte Differentiation through a Systematic Genomics Approach

<div><p>Multiple sclerosis (MS) is a neuroinflammatory disease characterized by a progressive loss of myelin and a failure of oligodendrocyte (OL)-mediated remyelination, particularly in the progressive phases of the disease. An improved understanding of the signaling mechanisms that control differentiation of OL precursors may lead to the identification of new therapeutic targets for remyelination in MS. About 100 mammalian Protein Tyrosine Phosphatases (PTPs) are known, many of which are involved in signaling both in health and disease. We have undertaken a systematic genomic approach to evaluate PTP gene activity in multiple sclerosis autopsies and in related <em>in vivo</em> and <em>in vitro</em> models of the disease. This effort led to the identification of Dusp15/VHY, a PTP previously believed to be expressed only in testis, as being transcriptionally regulated during OL differentiation and in MS lesions. Subsequent RNA interference studies revealed that Dusp15/VHY is a key regulator of OL differentiation. Finally, we identified PDGFR-beta and SNX6 as novel and specific Dusp15 substrates, providing an indication as to how this PTP might exert control over OL differentiation.</p> </div

PTPs the most strongly modulated during EAE in mice spinal cord and cerebellum.

<p>Number of PTP genes significantly modulated during the EAE time course in the spinal cord and in the cerebellum has been monitored and represented in two graphics. The number of PTP genes modulated increases dramatically over time. At day 28, the number of PTP genes modulated decreases until a basal level in cerebellum but remains high in the spinal cord. The highest fold changes in gene expression versus Sham animals have been reported in the table. Most of these PTPs have already been described in inflammatpry processes. Statistical analysis were performed using student <i>t-</i>test.</p

Phosphatase activity of GST-tagged full length Dusp15/VHY.

<p>A. Dusp15 phosphatase activity was assessed using the DiFMUP (6,8-difluoro-4-methyumbelliferyl phosphate) assay at the experimentally optimal enzyme concentration of 4 ng/mL. B. Optimal pH activity (pH 6) was determined by testing a pH range from pH 3 to 8. C. and D. Activity of Dusp15/VHY on phospho-peptides substrates corresponding respectively to pY₁₁₉ and pY₇₇₁ dephosphorylation sites of SNX6 (NED(pY₁₁₉)AGYIIPPAP) and PDGFR-β (IESSN(pY₇₇₁)MAPYD). VHY/Dusp15 was used at 4 ng/mL at pH6 and activity was detected using the Malachite Green phosphate detection assay. OD, Optical Density at 620 nm. Dissociation constant (Km) was calculated as the substrate concentration needed to reach V_max/2 and expressed as Mean ± S_EM of three different experiments.</p

Correlation chart between MBP expression and dusp15 expression over a time course of differentiation in olineu.

<p>Values expressed as fold induction <i>versus</i> undifferentiated controls (starting cultures) and correspond to the Mean ± SD of two different experiments (n = 2). Dusp15/VHY expression increases with time and correlates with MBP expression during the first steps of Oli-neu differentiation then Dusp15 expression reaches a maximum at 15 h prior to the MBP expression peak occurring at 24 h.</p

Literature data for expression of selected PTPs in purified cells from rodent brain.

a<p>Data extracted from GEO dataset GSE9566: GSM241928 (56A); GSM241929 (61D); GSM241930 (69E); GSM241931 (72A); GSM241932 (79E); GSM241933 (80O); GSM241934 (80P); GSM241935 (80Q); GSM241936 (81A); GSM241937 (81B). Samples designations correspond to the one used by the cited authors. Cell types were purified from post-natal mouse forebrains using FACS analysis. For more details see <i>Cahoy et al</i>, 2007.</p>b<p>Data extracted from Geo dataset GDS2379: GSM138218-GSM138222 (n = 5); GSM138223-GSM138229 (n = 4). OL cell types were purified from post-natal P7 rats using FACS analysis. For more details see Nielsen <i>et al</i>, 2006.</p

Ten-point standardized rating scale for EAE clinical score monitoring.

<p>The final score for each animal is determined by the addition of all the above mentioned categories. Note: Score  =  15 for dead animal.</p

Clinical data of MS and control autopsies included in the study.

*<p><i>CWM</i>: Control white matter; <i>CGM</i>: Control gray matter; <i>NAWM</i>: Normal appearing white matter; <i>WML</i>: White matter lesioned; <i>NAGM</i>: Normal appearing gray matter; <i>GML</i>: Gray matter lesioned.</p