Protective anti-tumor vaccination against glioblastoma expressing the MHC class II transactivator CIITA

Robust differentiation of NK cells from MSLN.CAR-IL-15-engineered human iPSCs with enhanced antitumor efficacy against solid tumors

Human induced pluripotent stem cells (iPSCs) offer a promising source for chimeric antigen receptor (CAR)-engineered natural killer (NK) products. However, complex iPSC-NK (iNK) manufacturing challenges clinical use. Here, we identified LiPSC-GR1.1 as a superior iPSC line for iNK production. By engineering LiPSC-GR1.1 with a mesothelin (MSLN)-targeting CAR and interleukin-15 (IL-15), we achieved robust differentiation of iPSCs into mature activated iNK cells with enhanced tumor killing efficacy, superior tumor homing, and vigorous proliferation. Single-cell transcriptomic analysis revealed that transforming growth factor-β (TGF-β)-producing tumor cells up-regulated major histocompatibility complex molecules and down-regulated MSLN post-CAR-IL-15 iNK treatment. Tumor-infiltrating CAR-IL-15 iNK cells exhibited high levels of CAR, IL-15, and NK-activating receptors, negligible checkpoint exhaustion markers, and extremely low levels of NK suppressive factors CISH, TGFBR2, and BATF, enabling them to sustain activation, metabolic fitness, and effective tumor killing within TGF-β-rich hypoxic tumor microenvironment. Overall, we developed MSLN.CAR-IL-15-engineered GR1.1-iNK therapy with enhanced antitumor efficacy for solid tumor treatment.

Adenoviral delivery of the CIITA transgene induces T-cell-mediated killing in glioblastoma organoids

The immunosuppressive nature of the tumor microenvironment poses a significant challenge to effective immunotherapies against glioblastoma (GB). Boosting the immune response is critical for successful therapy. Here, we adopted a cancer gene therapy approach to induce T-cell-mediated killing of the tumor through increased activation of the immune system. Patient-based three-dimensional (3D) GB models were infected with a replication-deficient adenovirus (AdV) armed with the class II major histocompatibility complex (MHC-II) transactivator (CIITA) gene (Ad-CIITA). Successful induction of surface MHC-II was achieved in infected GB cell lines and primary human GB organoids. Infection with an AdV carrying a mutant form of CIITA with a single amino acid substitution resulted in cytoplasmic accumulation of CIITA without subsequent MHC-II expression. Co-culture of infected tumor cells with either peripheral blood mononuclear cells (PBMCs) or isolated T-cells led to dramatic breakdown of GB organoids. Intriguingly, both wild-type and mutant Ad-CIITA, but not unarmed AdV, triggered immune-mediated tumor cell death in the co-culture system, suggesting an at least partially MHC-II-independent process. We further show that the observed cancer cell killing requires the presence of either CD8+ or CD4+ T-cells and direct contact between GB and immune cells. We did not, however, detect evidence of activation of canonical T-cell-mediated cell death pathways. Although the precise mechanism remains to be determined, these findings highlight the potential of AdV-mediated CIITA delivery to enhance T-cell-mediated immunity against GB.

Highlighting recent achievements to advance more effective cancer immunotherapy

From 17 to 19th October 2024, the XXI Italian Network for Bio-Immunotherapy of Tumors Meeting (NIBIT) took place in Palermo, in the marvelous historical location of Teatro Politeama, under the auspices of the Italian Association of Medical Oncology (AIOM), Italian Association of Cancer Research (AIRC), Fondazione Pezcoller, Italian Alliance against Cancer (ACC), Italian Lymphoma Foundation (FIL), Grazia Focacci Foundation and Melagioco Foundation. The conference covered a spectrum of topics ranging from target discovery to therapeutic advances in immuno-oncology, bringing world-renowned experts to present groundbreaking innovations in basic, translational, and clinical cancer research. Six sessions focused on cellular therapies, digital pathology, vaccines, tertiary lymphoid structures, and microenvironment in order to get deep insights on how to personalize diagnosis and therapies in the clinical setting. Young investigators had the opportunity to meet and greet their mentors, promoting the synergy of the academic and industrial sectors within the national and international panorama, discussing the application of artificial intelligence on multi-specific antibodies, drug conjugates, and antibody fusion proteins that are advancing the efficacy of precision medicine and minimizing off-target effects.

Non-Immune-Mediated, p27-Associated, Growth Inhibition of Glioblastoma by Class-II-Transactivator (CIITA)

BACKGROUND

Previous works have shown that the expression of Class-II-Transactivator (CIITA) in tumor cells reduces the growth of glioblastoma (GB) in animal models, but immune effects cannot solely explain this. Here, we searched for immune-independent effects of CIITA on the proliferation of GB.

METHODS

Murine GL261 and human U87, GM2 and GM3 malignant glioma cells were transfected with CIITA. NSG (immunodeficient) and nude (athymic) mice were injected in the striatum with GL261-wildtype (-WT) and -CIITA, and tumor growth was assessed by immunohistology and luminescence reporter genes. Clonogenic, sphere-formation, and 3D Matrigel-based in vitro growth assays were performed to compare the growth of WT versus CIITA-expressing murine and human cells. Bulk RNA sequencing and RT2 qRT-PCR profiler arrays were performed on these four cell lines to assess RNA expression changes following CIITA transfection. Western blot analysis on several proliferation-associated proteins was performed.

RESULTS

The intracerebral growth of murine GL261-CIITA cells was drastically reduced both in immunodeficient and athymic mice. Tumor growth was reduced in vitro in three of the four cell types. RNA sequencing and RT2 profiler array experiments revealed a modulation of gene expression in the PI3-Akt, MAPK- and cell-cycle regulation pathways following CIITA overexpression. Western blot analysis showed an upregulation of p27 in the growth-inhibited cells following this treatment. PDGFR-beta was downregulated in all cells. We did not find consistent regulation of other proteins involved in GB proliferation.

CONCLUSIONS

Proliferation is drastically reduced by CIITA in GB, both in vivo and in vitro, notably in association with p27-mediated inhibition of cell-cycle pathways.

An oncolytic HSV-1 vector induces a therapeutic adaptive immune response against glioblastoma

BACKGROUND

Glioblastoma (GBM) is the most frequent and aggressive brain tumor in adults with the lowest survival rates five years post-diagnosis. Oncolytic viruses (OVs) selectively target and damage cancer cells, and for this reason they are being investigated as new therapeutic tools also against GBM.

METHODS

An oncolytic herpes simplex virus type 1 (oHSV-1) with deletions in the γ34.5 neurovirulence gene and the US12 gene, expressing enhanced green fluorescent protein (EGFP-oHSV-1) as reporter gene was generated and tested for its capacity to infect and kill the murine GL261 glioblastoma (GBM) cell line. Syngeneic mice were orthotopically injected with GL261cells. Seven days post-implantation, EGFP-oHSV-1 was administered intratumorally. Twenty-one days after parental tumor challenge in the opposite brain hemisphere, mice were sacrified and their brains were analysed by immunohistochemistry to assess tumor presence and cell infiltrate.

RESULTS

oHSV-1 replicates and induces cell death of GL261 cells in vitro. A single intracranial injection of EGFP-oHSV-1 in established GL261 tumors significantly prolongs survival in all treated mice compared to placebo treatment. Notably, 45% of treated mice became long-term survivors, and rejected GL261 cells upon rechallenge in the contralateral brain hemisphere, indicating an anamnestic antitumoral immune response. Post-mortem analysis revealed a profound modification of the tumor microenvironment with increased infiltration of CD4 + and CD8 + T lymphocytes, intertumoral vascular collapse and activation and redistribution of macrophage, microglia, and astroglia in the tumor area, with the formation of intense fibrotic tissue suggestive of complete rejection in long-term survivor mice.

CONCLUSIONS

EGFP-oHSV1 demonstrates potent antitumoral activity in an immunocompetent GBM model as a monotherapy, resulting from direct cell killing combined with the stimulation of a protective adaptive immune response. These results open the way to possible application of our strategy in clinical setting.

Integrative transcriptome analysis reveals the molecular events underlying impaired T-cell responses in EGFR-mutant lung cancer

EGFR mutations are critical oncogenic drivers in lung adenocarcinoma (LUAD). However, the mechanisms by which they impact the tumor microenvironment (TME) and tumor immunity are unclear. Furthermore, the reasons underlying the poor response of EGFR-mutant (EGFR-MU) LUADs to immunotherapy with PD-1/PD-L1 inhibitors are unknown. Utilizing single-cell RNA (sc-RNA) and bulk RNA sequencing datasets, we conducted high-dimensional weighted gene coexpression network analysis to identify key genes and immune-related pathways contributing to the immunosuppressive TME. EGFR-MU cancer cells downregulated MHC class I genes to evade CD8+ cytotoxic T cells, expressed substantial levels of MHC class II molecules, and engaged with CD4+ regulatory T cells (Tregs). EGFR-MU tumors may recruit Tregs primarily through the CCL17/CCL22/CCR4 axis, leading to a Treg-enriched TME. High levels of MHC class II-positive cancer-associated fibroblasts and tumor endothelial cells were found within EGFR-MU tumors. Owing to the absence of costimulatory factors, they may inhibit rather than activate the tumor antigen-specific CD4+ T-cell response, contributing further to immune suppression. Multiplex immunohistochemistry analyses in a LUAD cohort confirmed increased expression of MHC class II molecules in cancer cells and fibroblasts in EGFR-MU tumors. Our research elucidates the highly immunosuppressive TME in EGFR-MU LUAD and suggests potential targets for effective immunotherapy.

Novel vaccination strategies based on optimal stimulation of CD4+ T helper cells for the treatment of oral squamous cell carcinoma

Oral Squamous Cell Carcinoma (OSCC) is the most common malignant tumor of the oral cavity. Despite recent advances in the field of oral cancer therapy, including the introduction of immunotherapeutic approaches, the 5-year survival rate remains steadily assessed around 50%. Thus, there is an urgent need for new therapeutic strategies. After the characterization of the immune phenotype of three human OSCC cell lines (CAL-27, SCC-25, and SCC-4) and one mouse OSCC cell line (MOC2) showing their similarities to resected patient tumors, we explored for the first time an experimental preclinical model of therapeutic vaccination with mouse OSCC MOC2 cell line stably expressing MHC class II antigens after CIITA gene transfection (MOC2-CIITA). Mice injected with MOC2-CIITA reject or strongly retard tumor growth; more importantly, vaccinated animals that fully reject MOC2-CIITA tumors display anti-tumor immunological memory protective against challenge with parental MOC2 tumor cells. Further experiments of adoptive cell transfer or in vivo cell depletion show that both CD4+ and CD8+ T lymphocytes prove fundamental in tumor rejection. This unprecedented approach for oral cancer opens the way for possible future translation of novel immunotherapeutic strategies to the human setting for the treatment of this tumor.

Engineering Challenges and Opportunities in Autologous Cellular Cancer Immunotherapy

The use of a patient's own immune or tumor cells, manipulated ex vivo, enables Ag- or patient-specific immunotherapy. Despite some clinical successes, there remain significant barriers to efficacy, broad patient population applicability, and safety. Immunotherapies that target specific tumor Ags, such as chimeric Ag receptor T cells and some dendritic cell vaccines, can mount robust immune responses against immunodominant Ags, but evolving tumor heterogeneity and antigenic downregulation can drive resistance. In contrast, whole tumor cell vaccines and tumor lysate-loaded dendritic cell vaccines target the patient's unique tumor antigenic repertoire without prior neoantigen selection; however, efficacy can be weak when lower-affinity clones dominate the T cell pool. Chimeric Ag receptor T cell and tumor-infiltrating lymphocyte therapies additionally face challenges related to genetic modification, T cell exhaustion, and immunotoxicity. In this review, we highlight some engineering approaches and opportunities to these challenges among four classes of autologous cell therapies.

Limited Effects of Class II Transactivator-Based Immunotherapy in Murine and Human Glioblastoma

BACKGROUND

The major histocompatibility complex type II is downregulated in glioblastoma (GB) due to the silencing of the major transcriptional regulator class II transactivator (CIITA). We investigated the pro-immunogenic potential of CIITA overexpression in mouse and human GB.

METHODS

The intracerebral growth of wildtype GL261-WT cells was assessed following contralateral injection of GL261-CIITA cells or flank injections with GL261-WT or GL261-CIITA cells. Splenocytes obtained from mice implanted intracerebrally with GL261-WT, GL261-CIITA cells or phosphate buffered saline (PBS) were transferred to other mice and subsequently implanted intracerebrally with GL261-WT. Human GB cells and (syngeneic) GB-infiltrating immune cells were isolated from surgical samples and co-cultured with GB cells expressing CIITA or not, followed by RT-qPCR assessment of the expression of key immune regulators.

RESULTS

Intracerebral vaccination of GL261-CIITA significantly reduced the subsequent growth of GL261-WT cells implanted contralaterally. Vaccination with GL261-WT or -CIITA subcutaneously, however, equivalently retarded the intracerebral growth of GL261 cells. Adoptive cell transfer experiments showed a similar antitumor potential of lymphocytes harvested from mice implanted intracerebrally with GL261-WT or -CIITA. Human GB-infiltrating myeloid cells and lymphocytes were not activated when cultured with CIITA-expressing GB cells. Tumor-infiltrating NK cells remained mostly inactivated when in co-culture with GB cells, regardless of CIITA.

CONCLUSION

these results question the therapeutic potential of CIITA-mediated immunotherapy in glioblastoma.

The NLR member CIITA: Master controller of adaptive and intrinsic immunity and unexpected tool in cancer immunotherapy

Human nucleotide-binding oligomerization domain (NOD)-like receptors (NLR) include a large family of proteins that have important functions in basic physio-pathological processes like inflammation, cell death and regulation of transcription of key molecules for the homeostasis of the immune system. They are all characterized by a common backbone structure (the STAND ATPase module consisting in a nucleotide-binding domain (NBD), an helical domain 1 (HD1) and a winged helix domain (WHD), used by both prokaryotes and eukaryotes as defense mechanism. In this review, we will focus on the MHC class II transactivator (CIITA), the master regulator of MHC class II (MHC-II) gene expression and the founding member of NLR. Although a consistent part of the described NLR family components is often recalled as innate or intrinsic immune sensors, CIITA in fact occupies a special place as a unique example of regulator of both intrinsic and adaptive immunity. The description of the discovery of CIITA and the genetic and molecular characterization of its expression will be followed by the most recent studies that have unveiled this dual role of CIITA, key molecule in intrinsic immunity as restriction factor for human retroviruses and precious tool to induce the expression of MHC-II molecules in cancer cells, rendering them potent surrogate antigen presenting cells (APC) for their own tumor antigens.