Polyoxazoline-Based Nanovaccine Synergizes with Tumor-Associated Macrophage Targeting and Anti-PD-1 Immunotherapy against Solid Tumors

Nanovaccines; Tumor immune microenvironment; Tumor-associated macrophagesNanovacunes; Microambient immune tumoral; Macròfags associats al tumorNanovacunas; Microambiente inmune tumoral; Macrófagos asociados al tumorImmune checkpoint blockade reaches remarkable clinical responses. However, even in the most favorable cases, half of these patients do not benefit from these therapies in the long term. It is hypothesized that the activation of host immunity by co-delivering peptide antigens, adjuvants, and regulators of the transforming growth factor (TGF)-β expression using a polyoxazoline (POx)-poly(lactic-co-glycolic) acid (PLGA) nanovaccine, while modulating the tumor-associated macrophages (TAM) function within the tumor microenvironment (TME) and blocking the anti-programmed cell death protein 1 (PD-1) can constitute an alternative approach for cancer immunotherapy. POx-Mannose (Man) nanovaccines generate antigen-specific T-cell responses that control tumor growth to a higher extent than poly(ethylene glycol) (PEG)-Man nanovaccines. This anti-tumor effect induced by the POx-Man nanovaccines is mediated by a CD8+-T cell-dependent mechanism, in contrast to the PEG-Man nanovaccines. POx-Man nanovaccine combines with pexidartinib, a modulator of the TAM function, restricts the MC38 tumor growth, and synergizes with PD-1 blockade, controlling MC38 and CT26 tumor growth and survival. This data is further validated in the highly aggressive and poorly immunogenic B16F10 melanoma mouse model. Therefore, the synergistic anti-tumor effect induced by the combination of nanovaccines with the inhibition of both TAM- and PD-1-inducing immunosuppression, holds great potential for improving immunotherapy outcomes in solid cancer patients.Funding: R.S.-F. and H.F.F. thank the following funding agencies for their generous support: The project that gave rise to these results has received funding from the “la Caixa” Foundation under the grant agreements LCF/PR/HR22/52420016, LCF/PR/HR19/52160021, and LCF/TR/CD20/52700005 (R.S.-F. and H.F.F). H.F.F thanks the generous financial support from The Fundação para a Ciência e Tecnologia-Ministério da Ciência, Tecnologia e Ensino Superior (FCT-MCTES) (EXPL/MED-QUI/1316/2021, PTDC/BTM-SAL/4350/2021, UTAP-EXPL/NPN/0041/2021, UIDB/04138/2020, UIDP/04138/2020). R.S.-F. thanks to the European Research Council (ERC) PoC Grant Agreement no. 101113390 and ERC Advanced Grant Agreement no. 835227, the Israel Science Foundation (1969/18), the Melanoma Research Alliance (Established Investigator Award no. 615808 to R.S.-F.), the Israel Cancer Research Fund (ICRF) Professorship award (no. PROF-18-682), the Morris Kahn Foundation. B.C. is supported by the FCT-MCTES (Ph.D. Fellowship SFRH/BD/131969/2017). The authors also acknowledge the NIH Tetramer Core Facility for the provision of Adpgk tetramers, in addition to the Comparative Pathology Unit of IMM and the Histopathology Facility of IGC for supporting the histopathological study

Identification of ZBTB18 as a novel colorectal tumor suppressor gene through genome-wide promoter hypermethylation analysis

Background Cancer initiation and progression are driven by genetic and epigenetic changes. Although genome/exome sequencing has significantly contributed to the characterization of the genetic driver alterations, further investigation is required to systematically identify cancer driver genes regulated by promoter hypermethylation. Results Using genome-wide analysis of promoter methylation in 45 colorectal cancer cell lines, we found that higher overall methylation levels were associated with microsatellite instability (MSI), faster proliferation and absence of APC mutations. Because epigenetically silenced genes could represent important oncogenic drivers, we used mRNA expression profiling of colorectal cancer cell lines and primary tumors to identify a subset of 382 (3.9%) genes for which promoter methylation was negatively associated with gene expression. Remarkably, a significant enrichment in zinc finger proteins was observed, including the transcriptional repressor ZBTB18. Re-introduction of ZBTB18 in colon cancer cells significantly reduced proliferation in vitro and in a subcutaneous xenograft mouse model. Moreover, immunohistochemical analysis revealed that ZBTB18 is frequently lost or reduced in colorectal tumors, and reduced ZBTB18 expression was found to be associated with lymph node metastasis and shorter survival of patients with locally advanced colorectal cancer. Conclusions We identified a set of 382 genes putatively silenced by promoter methylation in colorectal cancer that could significantly contribute to the oncogenic process. Moreover, as a proof of concept, we demonstrate that the epigenetically silenced gene ZBTB18 has tumor suppressor activity and is a novel prognostic marker for patients with locally advanced colorectal cancer.Peer reviewe