Human allogenic γδ T cells kill patient-derived glioblastoma cells expressing high levels of DNAM-1 ligands

CD155/PVR determines acute myeloid leukemia targeting by Delta One T cells

ABSTRACT

Relapsed or refractory acute myeloid leukemia (AML) remains a major therapeutic challenge. We have recently developed a Vδ1+ γδ T cell-based product for adoptive immunotherapy, named Delta One T (DOT) cells, and demonstrated their cytolytic capacity to eliminate AML cell lines and primary blasts in vitro and in vivo. However, the molecular mechanisms responsible for the broad DOT-cell recognition of AML cells remain poorly understood. Here, we dissected the role of natural killer (NK) cell receptor ligands in AML cell recognition by DOT cells. Screening of multiple AML cell lines highlighted a strong upregulation of the DNAM-1 ligands, CD155/pulmonary vascular resistance (PVR), CD112/nectin-2, as well as the NKp30 ligand, B7-H6, in contrast with NKG2D ligands. CRISPR-mediated ablation revealed key nonredundant and synergistic contributions of PVR and B7-H6 but not nectin-2 to DOT-cell targeting of AML cells. We further demonstrate that PVR and B7-H6 are critical for the formation of robust immunological synapses between AML and DOT cells. Importantly, PVR but not B7-H6 expression in primary AML samples predicted their elimination by DOT cells. These data provide new mechanistic insight into tumor targeting by DOT cells and suggest that assessing PVR expression levels may be highly relevant to DOT cell-based clinical trials.

Intratumoral IL-12 delivery via mesenchymal stem cells combined with PD-1 blockade leads to long-term antitumor immunity in a mouse glioblastoma model

BACKGROUND

Although PD-1 blockade is effective for treating several types of cancer, the efficacy of this agent in glioblastoma is largely limited. To overcome non-responders and the immunosuppressive tumor microenvironment, combinational immunotherapeutic strategies with anti-PD-1 need to be considered. Here, we developed IL-12-secreting mesenchymal stem cells (MSC_IL-12) with glioblastoma tropism and evaluated the therapeutic effects of anti-PD-1, MSC_IL-12, and their combination against glioblastoma.

METHODS

Therapeutic responses were evaluated using an immunocompetent mouse orthotopic model. Tumor-infiltrating lymphocytes (TILs) were analyzed using immunofluorescent imaging. Single-cell transcriptome was obtained from mouse brains after treatments.

RESULTS

Anti-PD-1 and MSC_IL-12 showed complete tumor remission in 25.0% (4/16) and 23.1% (3/13) of glioblastoma-implanted mice, respectively, and their combination yielded synergistic antitumor efficacy indicated by 50.0% (6/12) of complete tumor remission. Analyses of TILs revealed that anti-PD-1 increased CD8+ T cells, while MSC_IL-12 led to infiltration of CD4+ T cells and NK cells. Both therapies reduced frequencies of Tregs. All these aspects observed in each monotherapy group were superimposed in the combination group. Notably, no tumor growth was observed upon rechallenge in cured mice, indicating long-term immunity against glioblastoma provoked by the therapies. Single-cell RNA-seq data confirmed these results and revealed that the combined treatment led to immune-favorable tumor microenvironment-CD4+, CD8+ T cells, effector memory T cells, and activated microglia were increased, whereas exhausted T cells, Tregs, and M2 polarized microglia were reduced.

CONCLUSION

Anti-PD-1 and MSC_IL-12 monotherapies show long-term therapeutic responses, and their combination further enhances antitumor efficacy against glioblastoma via inducing immune-favorable tumor microenvironment.

Frequencies of 4 tumor-infiltrating lymphocytes potently predict survival in glioblastoma, an immune desert

BACKGROUND

GBM is an aggressive grade 4 primary brain tumor (BT), with a 5%-13% 5-year survival. Most human GBMs manifest as immunologically "cold" tumors or "immune deserts," yet the promoting or suppressive roles of specific lymphocytes within the GBM tumor microenvironment (TME) is of considerable debate.

METHODS

We used meticulous multiparametric flow cytometry (FC) to determine the lymphocytic frequencies in 102 GBMs, lower-grade gliomas, brain metastases, and nontumorous brain specimen. FC-attained frequencies were compared with frequencies estimated by "digital cytometry." The FC-derived data were combined with the patients' demographic, clinical, molecular, histopathological, radiological, and survival data.

RESULTS

Comparison of FC-derived data to CIBERSORT-estimated data revealed the poor capacity of digital cytometry to estimate cell frequencies below 0.2%, the frequency range of most immune cells in BTs. Isocitrate dehydrogenase (IDH) mutation status was found to affect TME composition more than the gliomas' pathological grade. Combining FC and survival data disclosed that unlike other cancer types, the frequency of helper T cells (Th) and cytotoxic T lymphocytes (CTL) correlated negatively with glioma survival. In contrast, the frequencies of γδ-T cells and CD56bright natural killer cells correlated positively with survival. A composite parameter combining the frequencies of these 4 tumoral lymphocytes separated the survival curves of GBM patients with a median difference of 10 months (FC-derived data; P < .0001, discovery cohort), or 4.1 months (CIBERSORT-estimated data; P = .01, validation cohort).

CONCLUSIONS

The frequencies of 4 TME lymphocytes strongly correlate with the survival of patients with GBM, a tumor considered an immune desert.

Isolation and expansion of pure and functional γδ T cells

γδ T cells are important components of the immune system due to their ability to elicit a fast and strong response against infected and transformed cells. Because they can specifically and effectively kill target cells in an MHC independent fashion, there is great interest to utilize these cells in anti-tumor therapies where antigen presentation may be hampered. Since only a small fraction of T cells in the blood or tumor tissue are γδ T cells, they require extensive expansion to allow for fundamental, preclinical and ex vivo research. Although expansion protocols can be successful, most are based on depletion of other cell types rather than γδ T cell specific isolation, resulting in unpredictable purity of the isolated fraction. Moreover, the primary focus only lies with expansion of Vδ2+ T cells, while Vδ1+ T cells likewise have anti-tumor potential. Here, we investigated whether γδ T cells directly isolated from blood could be efficiently expanded while maintaining function. γδ T cell subsets were isolated using MACS separation, followed by FACS sorting, yielding >99% pure γδ T cells. Isolated Vδ1+ and Vδ2+ T cells could effectively expand immediately after isolation or upon freeze/thawing and reached expansion ratios between 200 to 2000-fold starting from varying numbers using cytokine supported feeder stimulations. MACS/FACS isolated and PHA stimulated γδ T cells expanded as good as immobilized antibody mediated stimulated cells in PBMCs, but delivered purer cells. After expansion, potential effector functions of γδ T cells were demonstrated by IFN-γ, TNF-α and granzyme B production upon PMA/ionomycin stimulation and effective killing capacity of multiple tumor cell lines was confirmed in killing assays. In conclusion, pure γδ T cells can productively be expanded while maintaining their anti-tumor effector functions against tumor cells. Moreover, γδ T cells could be expanded from low starting numbers suggesting that this protocol may even allow for expansion of cells extracted from tumor biopsies.

γδ T cells as a potential therapeutic agent for glioblastoma

Although γδ T cells comprise a small population of T cells, they perform important roles in protecting against infection and suppressing tumors. With their distinct tissue-localizing properties, combined with their various target recognition mechanisms, γδ T cells have the potential to become an effective solution for tumors that do not respond to current therapeutic procedures. One such tumor, glioblastoma (GBM), is a malignant brain tumor with the highest World Health Organization grade and therefore the worst prognosis. The immune-suppressive tumor microenvironment (TME) and immune-evasive glioma stem cells are major factors in GBM immunotherapy failure. Currently, encouraged by the strong anti-tumoral function of γδ T cells revealed at the preclinical and clinical levels, several research groups have shown progression of γδ T cell-based GBM treatment. However, several limitations still exist that block effective GBM treatment using γδ T cells. Therefore, understanding the distinct roles of γδ T cells in anti-tumor immune responses and the suppression mechanism of the GBM TME are critical for successful γδ T cell-mediated GBM therapy. In this review, we summarize the effector functions of γδ T cells in tumor immunity and discuss current advances and limitations of γδ T cell-based GBM immunotherapy. Additionally, we suggest future directions to overcome the limitations of γδ T cell-based GBM immunotherapy to achieve successful treatment of GBM.

B7H3-targeting chimeric antigen receptor modification enhances antitumor effect of Vγ9Vδ2 T cells in glioblastoma

BACKGROUND

Glioblastoma (GBM) is a highly aggressive primary brain tumor with a poor prognosis. This study investigates the therapeutic potential of human Vγ9Vδ2 T cells in GBM treatment. The sensitivity of different glioma specimens to Vγ9Vδ2 T cell-mediated cytotoxicity is assessed using a patient-derived tumor cell clusters (PTCs) model.

METHODS

The study evaluates the anti-tumor effect of Vγ9Vδ2 T cells in 26 glioma cases through the PTCs model. Protein expression of BTN2A1 and BTN3A1, along with gene expression related to lipid metabolism and glioma inflammatory response pathways, is analyzed in matched tumor tissue samples. Additionally, the study explores two strategies to re-sensitize tumors in the weak anti-tumor effect (WAT) group: utilizing a BTN3A1 agonistic antibody or employing bisphosphonates to inhibit farnesyl diphosphate synthase (FPPS). Furthermore, the study investigates the efficacy of genetically engineered Vγ9Vδ2 T cells expressing Car-B7H3 in targeting diverse GBM specimens.

RESULTS

The results demonstrate that Vγ9Vδ2 T cells display a stronger anti-tumor effect (SAT) in six glioma cases, while showing a weaker effect (WAT) in twenty cases. The SAT group exhibits elevated protein expression of BTN2A1 and BTN3A1, accompanied by differential gene expression related to lipid metabolism and glioma inflammatory response pathways. Importantly, the study reveals that the WAT group GBM can enhance Vγ9Vδ2 T cell-mediated killing sensitivity by incorporating either a BTN3A1 agonistic antibody or bisphosphonates. Both approaches support TCR-BTN mediated tumor recognition, which is distinct from the conventional MHC-peptide recognition by αβ T cells. Furthermore, the study explores an alternative strategy by genetically engineering Vγ9Vδ2 T cells with Car-B7H3, and both non-engineered and Car-B7H3 Vγ9Vδ2 T cells demonstrate promising efficacy in vivo, underscoring the versatile potential of Vγ9Vδ2 T cells for GBM treatment.

CONCLUSIONS

Vγ9Vδ2 T cells demonstrate a robust anti-tumor effect in some glioma cases, while weaker in others. Elevated BTN2A1 and BTN3A1 expression correlates with improved response. WAT group tumors can be sensitized using a BTN3A1 agonistic antibody or bisphosphonates. Genetically engineered Vγ9Vδ2 T cells, i.e.,  Car-B7H3, show promising efficacy. These results together highlight the versatility of Vγ9Vδ2 T cells for GBM treatment.

Human gamma-delta (γδ) T cell therapy for glioblastoma: A novel alternative to overcome challenges of adoptive immune cell therapy

Glioblastoma is the most common brain malignancy with devastating prognosis. Numerous clinical trials using various target therapeutic agents have failed and recent clinical trials using check point inhibitors also failed to provide survival benefits for glioblastoma patients. Adoptive T cell transfer is suggested as a novel therapeutic approach that has exhibited promise in preliminary clinical studies. However, the clinical outcomes are inconsistent, and there are several limitations of current adoptive T cell transfer strategies for glioblastoma treatment. As an alternative cell therapy, gamma-delta (γδ) T cells have been recently introduced for several cancers including glioblastoma. Since the leading role of γδ T cells is immune surveillance by recognizing a broad range of ligands including stress molecules, phosphoantigens, or lipid antigens, recent studies have suggested the potential benefits of γδ T cell transfer against glioblastomas. However, γδ T cells, as a small subset (1-5%) of T cells in human peripheral blood, are relatively unknown compared to conventional alpha-beta (αβ) T cells. In this context, our study introduced γδ T cells as an alternative and novel option to overcome several challenges regarding immune cell therapy in glioblastoma treatment. We described the unique characteristics and advantages of γδ T cells compared to conventional αβ T cells and summarize several recent preclinical studies using human gamma-delta T cell therapy for glioblastomas. Finally, we suggested future direction of human γδ T cell therapy for glioblastomas.