TGFβ suppresses CD8+ T cell expression of CXCR3 and tumor trafficking

A landscape of checkpoint blockade resistance in cancer: underlying mechanisms and current strategies to overcome resistance

The discovery of immune checkpoints and the development of immune checkpoint inhibitors (ICI) have achieved a durable response in advanced-stage cancer patients. However, there is still a high proportion of patients who do not benefit from ICI therapy due to a lack of response when first treated (primary resistance) or detection of disease progression months after objective response is observed (acquired resistance). Here, we review the current FDA-approved ICI for the treatment of certain solid malignancies, evaluate the contrasting responses to checkpoint blockade in different cancer types, explore the known mechanisms associated with checkpoint blockade resistance (CBR), and assess current strategies in the field that seek to overcome these mechanisms. In order to improve current therapies and develop new ones, the immunotherapy field still has an unmet need in identifying other molecules that act as immune checkpoints, and uncovering other mechanisms that promote CBR.

Fibroblast activation protein-targeted near-infrared photoimmunotherapy depletes immunosuppressive cancer-associated fibroblasts and remodels local tumor immunity

BACKGROUND

Cancer-associated fibroblasts (CAFs) in the tumor microenvironment (TME) play a critical role in tumor immunosuppression. However, targeted depletion of CAFs is difficult due to their diverse cells of origin and the resulting lack of specific surface markers. Near-infrared photoimmunotherapy (NIR-PIT) is a novel cancer treatment that leads to rapid cell membrane damage.

METHODS

In this study, we used anti-mouse fibroblast activation protein (FAP) antibody to target FAP+ CAFs (FAP-targeted NIR-PIT) and investigated whether this therapy could suppress tumor progression and improve tumor immunity.

RESULTS

FAP-targeted NIR-PIT induced specific cell death in CAFs without damaging adjacent normal cells. Furthermore, FAP-targeted NIR-PIT treated mice showed significant tumor regression in the CAF-rich tumor model accompanied by an increase in CD8+ tumor infiltrating lymphocytes (TILs). Moreover, treated tumors showed increased levels of IFN-γ, TNF-α, and IL-2 in CD8+ TILs compared with non-treated tumors, suggesting enhanced antitumor immunity.

CONCLUSIONS

Cancers with FAP-positive CAFs in their TME grow rapidly and FAP-targeted NIR-PIT not only suppresses their growth but improves tumor immunosuppression. Thus, FAP-targeted NIR-PIT is a potential therapeutic strategy for selectively targeting the TME of CAF+ tumors.

Development of pharmacological immunoregulatory anti-cancer therapeutics: current mechanistic studies and clinical opportunities

Immunotherapy represented by anti-PD-(L)1 and anti-CTLA-4 inhibitors has revolutionized cancer treatment, but challenges related to resistance and toxicity still remain. Due to the advancement of immuno-oncology, an increasing number of novel immunoregulatory targets and mechanisms are being revealed, with relevant therapies promising to improve clinical immunotherapy in the foreseeable future. Therefore, comprehending the larger picture is important. In this review, we analyze and summarize the current landscape of preclinical and translational mechanistic research, drug development, and clinical trials that brought about next-generation pharmacological immunoregulatory anti-cancer agents and drug candidates beyond classical immune checkpoint inhibitors. Along with further clarification of cancer immunobiology and advances in antibody engineering, agents targeting additional inhibitory immune checkpoints, including LAG-3, TIM-3, TIGIT, CD47, and B7 family members are becoming an important part of cancer immunotherapy research and discovery, as are structurally and functionally optimized novel anti-PD-(L)1 and anti-CTLA-4 agents and agonists of co-stimulatory molecules of T cells. Exemplified by bispecific T cell engagers, newly emerging bi-specific and multi-specific antibodies targeting immunoregulatory molecules can provide considerable clinical benefits. Next-generation agents also include immune epigenetic drugs and cytokine-based therapeutics. Cell therapies, cancer vaccines, and oncolytic viruses are not covered in this review. This comprehensive review might aid in further development and the fastest possible clinical adoption of effective immuno-oncology modalities for the benefit of patients.

Expressions of CXCR3 and PD-1 on T cells and their clinical relevance in colorectal cancer

PURPOSE

Clinical application of immunotherapy represented by Programmed Death-1 (PD-1) monoclonal antibody has changed the treatment paradigm for colorectal cancer (CRC), and tumor-infiltrating T lymphocytes are critical for anti-PD-1 therapy in CRC. However, there are few studies on the relationship between the expression CXCR3 on T lymphocytes and the clinical aspects of CRC. In this study, we analyzed the expression levels of CXCR3 and PD-1 in CD8+ and CD4+ T lymphocytes in healthy donors (HDs) and patients with CRC.

METHODS

We detected the expressions of CXCR3 and PD-1 on T lymphocytes in peripheral blood of healthy donors as well as peripheral blood, tumor tissue and para-cancerous tissues of patients with CRC using flow cytometry. We also analyzed the relationship between the expressions of CXCR3 and PD-1 on T lymphocytes and the pathological characteristics of CRC using t test.

RESULTS

Expression of CXCR3 on tumor-infiltrating T lymphocytes was lower, whereas the expression of PD-1 was higher than that on para-cancerous tissues and PB in patients with CRC. In patients with lymph node metastasis of CRC, the expressions levels of CXCR3+ PD-1+ on tumor-infiltrating CD8+ and CD4+ T lymphocytes were higher than those in patients without lymph node metastasis. The levels of CXCR3+ PD-1+ expressions differed depending on the primary tumor site.

CONCLUSION

Expressions of CXCR3 and PD-1 on tumor-infiltrating T lymphocytes are related to the development of CRC and metastasis, providing clues for exploring the pathogenesis of CRC and developing new strategies for tumor immunotherapy.

Design, synthesis and evaluation of a pyrazolo[3,4-d]pyrimidine derivative as a novel and potent TGFβ1R1 inhibitor

The transforming growth factor β1 (TGFβ1)/SMAD signaling pathway regulates many vital physiological processes. The development of potent inhibitors targeting activin receptor-like kinase 5 (ALK5) would provide potential treatment reagents for various diseases. A significant number of ALK5 inhibitors have been discovered, and they are currently undergoing clinical evaluation at various stages. However, the clinical demands were far from being met. In this study, we utilized an alternative conformation-similarity-based virtual screening (CSVS) combined with a fragment-based drug designing (FBDD) strategy to efficiently discover a potent and active hit with a novel chemical scaffold. After structural optimization in the principle of group replacement, compound 57 was identified as the most promising ALK5 inhibitor. Compound 57 demonstrated significant inhibitory effects against the TGF-β1/SMAD signaling pathway. It could markedly attenuate the production of extracellular matrix (ECM) and deposition of collagen. Also, the lead compound showed adequate pharmacokinetic (PK) properties and good in vivo tolerance. Moreover, treatment with compound 57 in two different xerograph models showed significant inhibitory effects on the growth of pancreatic cancer cells. These results suggested that lead compound 57 refers as a promising ALK5 inhibitor both in vitro and in vivo, which merits further validation.

High-Dimensional Analyses Reveal IL15 Enhances Activation of Sipuleucel-T Lymphocyte Subsets and Reverses Immunoresistance

Sipuleucel-T (sip-T) is the only FDA-approved autologous cellular immunotherapy for metastatic castration-resistant prostate cancer (mCRPC). To elucidate parameters of the response profile to this therapy, we report high-dimensional analyses of sip-T using cytometry by time of flight (CyTOF) and show a lymphoid predominance, with CD3+ T cells constituting the highest proportion (median ∼60%) of sip-T, followed by B cells, and natural killer (NK) and NKT cells. We hypothesized that treatment of sip-T with homeostatic cytokines known to activate/expand effector lymphocytes could augment efficacy against prostate tumors. Of the cytokines tested, IL15 was the most effective at enhancing activation and proliferation of effector lymphocytes, as well as augmenting tumor cytotoxicity in vitro. Co-culture of sip-T with IL15 and control or prostate-relevant antigens showed substantial activation and expansion of CD8+ T cells and NKT cells in an antigen-specific manner. Adoptive transfer of IL15-treated sip-T into NSG mice resulted in more potent prostate tumor growth inhibition compared with control sip-T. Evaluation of tumor-infiltrating lymphocytes revealed a 2- to 14-fold higher influx of sip-T and a significant increase in IFNγ producing CD8+ T cells and NKT cells within the tumor microenvironment in the IL15 group. In conclusion, we put forward evidence that IL15 treatment can enhance the functional antitumor immunity of sip-T, providing rationale for combining IL15 or IL15 agonists with sip-T to treat patients with mCRPC.

Kinetics of IFNγ-Induced Cytokines and Development of Immune-Related Adverse Events in Patients Receiving PD-(L)1 Inhibitors

Immune checkpoint inhibitors (ICI) have the potential to trigger unpredictable immune-related adverse events (irAEs), which can be severe. The underlying mechanisms of these events are not fully understood. As PD-L1 is upregulated by IFN, the heightened immune activation resulting from PD-1/PD-L1 inhibition may enhance the IFN response, triggering the expression of IFN-inducible genes and contributing to irAE development and its severity. In this study, we investigated the interplay between irAEs and the expression of IFN-inducible chemokines and cytokines in 134 consecutive patients with solid tumours treated with PD-(L)1 inhibitors as monotherapy or in combination with chemotherapy or other immunotherapy agents. We compared the plasma levels of IFN-associated cytokines (CXCL9/10/11, IL-18, IL-10, IL-6 and TGFβ) at various time points (at baseline, at the onset of irAE and previous to irAE onset) in three patient groups categorized by irAE development and severity: patients with serious irAEs, mild irAEs and without irAEs after PD-(L)1 inhibitors. No differences were observed between groups at baseline. However, patients with serious irAEs exhibited significant increases in CXCL9/10/11, IL-18 and IL-10 levels at the onset of the irAE compared to baseline. A network analysis and correlation patterns highlighted a robust relationship among these chemokines and cytokines at serious-irAE onset. Combining all of the analysed proteins in a cluster analysis, we identified a subgroup of patients with a higher incidence of serious irAEs affecting different organs or systems. Finally, an ROC analysis and a decision tree model proposed IL-18 levels ≥ 807 pg/mL and TGFβ levels ≤ 114 pg/mL as predictors for serious irAEs in 90% of cases. In conclusion, our study elucidates the dynamic changes in cytokine profiles associated with serious irAE development during treatment with PD-(L)1 inhibitors. The study's findings offer valuable insights into the intricate IFN-induced immune responses associated with irAEs and propose potential predictive markers for their severity.

High-multiplex single-cell imaging analysis reveals tumor immune contexture associated with clinical outcomes after CAR T cell therapy

Chimeric antigen receptor (CAR) T cell therapy has made great progress in treating lymphoma, yet patient outcomes still vary greatly. The lymphoma microenvironment may be an important factor in the efficacy of CAR T therapy. In this study, we designed a highly multiplexed imaging mass cytometry (IMC) panel to simultaneously quantify 31 biomarkers from 13 patients with relapsed/refractory diffuse large B cell lymphoma (DLBCL) who received CAR19/22 T cell therapy. A total of 20 sections were sampled before CAR T cell infusion or after infusion when relapse occurred. A total of 35 cell clusters were identified, annotated, and subsequently redefined into 10 metaclusters. The CD4+ T cell fraction was positively associated with remission duration. Significantly higher Ki67, CD57, and TIM3 levels and lower CD69 levels in T cells, especially the CD8+/CD4+ Tem and Te cell subsets, were seen in patients with poor outcomes. Cellular neighborhood containing more immune cells was associated with longer remission. Fibroblasts and vascular endothelial cells resided much closer to tumor cells in patients with poor response and short remission after CAR T therapy. Our work comprehensively and systematically dissects the relationship between cell composition, state, and spatial arrangement in the DLBCL microenvironment and the outcomes of CAR T cell therapy, which is beneficial to predict CAR T therapy efficacy.

CD8+ T cell-based cancer immunotherapy

The immune system in humans is a defense department against both exogenous and endogenous hazards, where CD8+ T cells play a crucial role in opposing pathological threats. Various immunotherapies based on CD8+ T cells have emerged in recent decades, showing their promising results in treating intractable diseases. However, in the fight against the constantly changing and evolving cancers, the formation and function of CD8+ T cells can be challenged by tumors that might train a group of accomplices to resist the T cell killing. As cancer therapy stepped into the era of immunotherapy, understanding the physiological role of CD8+ T cells, studying the machinery of tumor immune escape, and thereby formulating different therapeutic strategies become the imperative missions for clinical and translational researchers to fulfill. After brief basics of CD8+ T cell-based biology is covered, this review delineates the mechanisms of tumor immune escape and discusses different cancer immunotherapy regimens with their own advantages and setbacks, embracing challenges and perspectives in near future.

EGR1 Mediated Reduction of Fibroblast Secreted-TGF-β1 Exacerbated CD8+ T Cell Inflammation and Migration in Vitiligo

Vitiligo is a T cell-mediated depigment skin disease caused by the complex interplay between melanocyte dysfunction, environmental stimulation, and dysregulated immune signals. Transforming growth factor-β1 (TGF-β1), which typically derives from regulatory T cells, has long been identified at low levels in the peripheral system of vitiligo patients. Here, through RNA-sequencing and transcription factor enrichment, we revealed that in response to CD8+ T cell-secreted interferon-gamma (IFN-γ), stromal fibroblast downregulates early growth response 1 (EGR1) activity, leading to TGF-β1 deficiency. The defective immune regulation loop further exacerbated local CD8+ T cell inflammation and promoted inflammatory cell migration in vitiligo. Thus, fibroblast-derived TGF-β1 plays an important stromal signal in vitiligo pathogenesis.

Oral probiotics microgel plus Galunisertib reduced TGF-β blockade resistance and enhanced anti-tumor immune responses in colorectal cancer

Transforming growth factor β (TGF-β), a versatile immunosuppressive cytokine, has gained increasing attention as a potential target for cancer immunotherapy. However, current strategies are constrained by tumor heterogeneity and drug resistance. Therapeutic probiotics, such as Escherichia coli Nissle1917 (EcN), not only regulate the gut microbiota to increase beneficial bacteria with anti-tumor effects, but also modulate immune factors within the body, thereby enhancing immunity. In this study, we developed an oral microgel delivery system of EcN@(CS-SA)2 by electrostatic interaction between chitosan (CS) and sodium alginate (SA), aiming to enhance its bioavailability in the gastrointestinal tract (GIT). Notably, EcN@(CS-SA)2 microgel showed a synergistic enhancement of the anti-tumor efficacy of Galunisertib (Gal, a TGF-β inhibitor) by inducing apoptosis and immunogenic cell death (ICD) in tumor cells, as well as promoting increased infiltration of CD8+ T cells into the tumor microenvironment (TME).

SMAD7 expression in CAR-T cells improves persistence and safety for solid tumors

Despite the tremendous progress of chimeric antigen receptor T (CAR-T) cell therapy in hematological malignancies, their application in solid tumors has been limited largely due to T-cell exhaustion in the tumor microenvironment (TME) and systemic toxicity caused by excessive cytokine release. As a key regulator of the immunosuppressive TME, TGF-β promotes cytokine synthesis via the NF-κB pathway. Here, we coexpressed SMAD7, a suppressor of TGF-β signaling, with a HER2-targeted CAR in engineered T cells. These novel CAR-T cells displayed high cytolytic efficacy and were resistant to TGF-β-triggered exhaustion, which enabled sustained tumoricidal capacity after continuous antigen exposure. Moreover, SMAD7 substantially reduced the production of inflammatory cytokines by antigen-primed CAR-T cells. Mechanistically, SMAD7 downregulated TGF-β receptor I and abrogated the interplay between the TGF-β and NF-κB pathways in CAR-T cells. As a result, these CAR-T cells persistently inhibited tumor growth and promoted the survival of tumor-challenged mice regardless of the hostile tumor microenvironment caused by a high concentration of TGF-β. SMAD7 coexpression also enhanced CAR-T-cell infiltration and persistent activation in patient-derived tumor organoids. Therefore, our study demonstrated the feasibility of SMAD7 coexpression as a novel approach to improve the efficacy and safety of CAR-T-cell therapy for solid tumors.

TGFβ-specific T cells induced by a TGFβ-derived immune modulatory vaccine both directly and indirectly modulate the phenotype of tumor-associated macrophages and fibroblasts

The tumor microenvironment (TME) of pancreatic cancer is highly immunosuppressive. We recently developed a transforming growth factor (TGF)β-based immune modulatory vaccine that controlled tumor growth in a murine model of pancreatic cancer by targeting immunosuppression and desmoplasia in the TME. We found that treatment with the TGFβ vaccine not only reduced the percentage of M2-like tumor-associated macrophages (TAMs) and cancer-associated fibroblasts (CAFs) in the tumor but polarized CAFs away from the myofibroblast-like phenotype. However, whether the immune modulatory properties of the TGFβ vaccine on TAM and CAF phenotypes are a direct consequence of the recognition and subsequent targeting of these subsets by TGFβ-specific T cells or an indirect consequence of the overall modulation induced within the TME remains unknown. Recognition of M2 macrophages and fibroblast by TGFβ-specific T cells was assessed by ELISpot and flow cytometry. The indirect and direct effects of the TGFβ vaccine on these cell subsets were evaluated by culturing M2 macrophages or fibroblasts with tumor-conditioned media or with T cells isolated from the spleen of mice treated with the TGFβ vaccine or a control vaccine, respectively. Changes in phenotype were assessed by flow cytometry and Bio-Plex multiplex system (Luminex). We found that TGFβ-specific T cells induced by the TGFβ vaccine can recognize M2 macrophages and fibroblasts. Furthermore, we demonstrated that the phenotype of M2 macrophages and CAFs can be directly modulated by TGFβ-specific T cells induced by the TGFβ vaccine, as well as indirectly modulated as a result of the immune-modulatory effects of the vaccine within the TME. TAMs tend to have tumor-promoting functions, harbor an immunosuppressive phenotype and are linked to decreased overall survival in pancreatic cancer when they harbor an M2-like phenotype. In addition, myofibroblast-like CAFs create a stiff extracellular matrix that restricts T cell infiltration, impeding the effectiveness of immune therapies in desmoplastic tumors, such as pancreatic ductal adenocarcinoma. Reducing immunosuppression and immune exclusion in pancreatic tumors by targeting TAMs and CAFs with the TGFβ-based immune modulatory vaccine emerges as an innovative strategy for the generation of a more favorable environment for immune-based therapies, such as immune checkpoint inhibitors.

Cancer-associated fibroblast spatial heterogeneity and EMILIN1 expression in the tumor microenvironment modulate TGF-β activity and CD8+ T-cell infiltration in breast cancer

Rationale: The tumor microenvironment (TME) and its multifaceted interactions with cancer cells are major targets for cancer treatment. Single-cell technologies have brought major insights into the TME, but the resulting complexity often precludes conclusions on function. Methods: We combined single-cell RNA sequencing and spatial transcriptomic data to explore the relationship between different cancer-associated fibroblast (CAF) populations and immune cell exclusion in breast tumors. The significance of the findings was then evaluated in a cohort of tumors (N=75) from breast cancer patients using immunohistochemistry analysis. Results: Our data show for the first time the degree of spatial organization of different CAF populations in breast cancer. We found that IL-iCAFs, Detox-iCAFs, and IFNγ-iCAFs tended to cluster together, while Wound-myCAFs, TGFβ-myCAFs, and ECM-myCAFs formed another group that overlapped with elevated TGF-β signaling. Differential gene expression analysis of areas with CD8+ T-cell infiltration/exclusion within the TGF-β signaling-rich zones identified elastin microfibrillar interface protein 1 (EMILIN1) as a top modulated gene. EMILIN1, a TGF-β inhibitor, was upregulated in IFNγ-iCAFs directly modulating TGFβ immunosuppressive function. Histological analysis of 75 breast cancer samples confirmed that high EMILIN1 expression in the tumor margins was related to high CD8+ T-cell infiltration, consistent with our spatial gene expression analysis. High EMILIN1 expression was also associated with better prognosis of patients with breast cancer, underscoring its functional significance for the recruitment of cytotoxic T cells into the tumor area. Conclusion: Our data show that correlating TGF-β signaling to a CAF subpopulation is not enough because proteins with TGF-β-modulating activity originating from other CAF subpopulations can alter its activity. Therefore, therapeutic targeting should remain focused on biological processes rather than on specific CAF subtypes.

Differential induction of T-cell tolerance by tumour fibroblast subsets

T-cell immunotherapy is now a first-line cancer treatment for metastatic melanoma and some lung cancer subtypes, which is a welcome clinical success. However, the response rates observed in these diseases are not yet replicated across other prominent solid tumour types, particularly stromal-rich subtypes with a complex microenvironment that suppresses infiltrating T cells. Cancer-associated fibroblasts (CAFs) are one of the most abundant and pro-pathogenic players in the tumour microenvironment, promoting tumour neogenesis, persistence and metastasis. Accumulating evidence is clear that CAFs subdue anti-tumour T-cell immunity and interfere with immunotherapy. CAFs can be grouped into different subtypes that operate synergistically to suppress T-cell function, including myofibroblastic CAFs, inflammatory CAFs and antigen-presenting CAFs, among other nomenclatures. Here, we review the mechanisms used by CAFs to induce T- cell tolerance and how these functions are likely to affect immunotherapy outcomes.

Transforming Growth Factor Beta 2 (TGFB2) and Interferon Gamma Receptor 2 (IFNGR2) mRNA Levels in the Brainstem Tumor Microenvironment (TME) Significantly Impact Overall Survival in Pediatric DMG Patients

This hypothesis-generating study characterized the mRNA expression profiles and prognostic impacts of antigen-presenting cell (APC) markers (CD14, CD163, CD86, and ITGAX/CD11c) in pediatric brainstem diffuse midline glioma (pbDMG) tumors. We also assessed the mRNA levels of two therapeutic targets, transforming growth factor beta 2 (TGFB2) and interferon gamma receptor 2 (IFNGR2), for their biomarker potentials in these highly aggressive pbDMG tumors. The expressions of CD14, CD163, and ITGAX/CD11c mRNAs exhibited significant decreases of 1.64-fold (p = 0.037), 1.75-fold (p = 0.019), and 3.33-fold (p < 0.0001), respectively, in pbDMG tumors relative to those in normal brainstem/pons samples. The pbDMG samples with high levels of TGFB2 in combination with low levels of APC markers, reflecting the cold immune state of pbDMG tumors, exhibited significantly worse overall survival outcomes at low expression levels of CD14, CD163, and CD86. The expression levels of IFNGR2 and TGFB2 (1.51-fold increase (p = 0.002) and 1.58-fold increase (p = 5.5 × 10-4), respectively) were significantly upregulated in pbDMG tumors compared with normal brainstem/pons samples. We performed multivariate Cox proportional hazards modelling that showed TGFB2 was a prognostic indicator (HR for patients in the TGFB2high group of pbDMG patients = 2.88 (1.12-7.39); p = 0.028) for poor overall survival (OS) and was independent of IFNGR2 levels, the age of the patient, and the significant interaction effect observed between IFNGR2 and TGFB2 (p = 0.015). Worse survival outcomes in pbDMG patients when comparing high versus low TGFB2 levels in the context of low IFNGR2 levels suggest that the abrogation of the TGFB2 mRNA expression in the immunologically cold tumor microenvironment can be used to treat pbDMG patients. Furthermore, pbDMG patients with low levels of JAK1 or STAT1 mRNA expression in combination with high levels of TGFB2 also exhibited poor OS outcomes, suggesting that the inclusion of (interferon-gamma) IFN-γ to stimulate and activate JAK1 and STAT1 in anti-tumor APC cells present the brainstem TME can enhance the effect of the TGFB2 blockade.

CAR-T treatment for cancer: prospects and challenges

Chimeric antigen receptor (CAR-T) cell therapy has been widely used in hematological malignancies and has achieved remarkable results, but its long-term efficacy in solid tumors is greatly limited by factors such as the tumor microenvironment (TME). In this paper, we discuss the latest research and future views on CAR-T cell cancer immunotherapy, compare the different characteristics of traditional immunotherapy and CAR-T cell therapy, introduce the latest progress in CAR-T cell immunotherapy, and analyze the obstacles that hinder the efficacy of CAR-T cell therapy, including immunosuppressive factors, metabolic energy deficiency, and physical barriers. We then further discuss the latest therapeutic strategies to overcome these barriers, as well as management decisions regarding the possible safety issues of CAR-T cell therapy, to facilitate solutions to the limited use of CAR-T immunotherapy.

TGF-β broadly modifies rather than specifically suppresses reactivated memory CD8 T cells in a dose-dependent manner

Transforming growth factor β (TGF-β) directly acts on naive, effector, and memory T cells to control cell fate decisions, which was shown using genetic abrogation of TGF-β signaling. TGF-β availability is altered by infections and cancer; however, the dose-dependent effects of TGF-β on memory CD8 T cell (Tmem) reactivation are still poorly defined. We examined how activation and TGF-β signals interact to shape the functional outcome of Tmem reactivation. We found that TGF-β could suppress cytotoxicity in a manner that was inversely proportional to the strength of the activating TCR or proinflammatory signals. In contrast, even high doses of TGF-β had a comparatively modest effect on IFN-γ expression in the context of weak and strong reactivation signals. Since CD8 Tmem may not always receive TGF-β signals concurrently with reactivation, we also explored whether the temporal order of reactivation versus TGF-β signals is of importance. We found that exposure to TGF-β before or after an activation event were both sufficient to reduce cytotoxic effector function. Concurrent ATAC-seq and RNA-seq analysis revealed that TGF-β altered ~10% of the regulatory elements induced by reactivation and also elicited transcriptional changes indicative of broadly modulated functional properties. We confirmed some changes on the protein level and found that TGF-β-induced expression of CCR8 was inversely proportional to the strength of the reactivating TCR signal. Together, our data suggest that TGF-β is not simply suppressing CD8 Tmem but modifies functional and chemotactic properties in context of their reactivation signals and in a dose-dependent manner.

Transforming Growth Factor-β Blockade in Pancreatic Cancer Enhances Sensitivity to Combination Chemotherapy

BACKGROUND & AIMS

Transforming growth factor-b (TGFb) plays pleiotropic roles in pancreatic cancer, including promoting metastasis, attenuating CD8 T-cell activation, and enhancing myofibroblast differentiation and deposition of extracellular matrix. However, single-agent TGFb inhibition has shown limited efficacy against pancreatic cancer in mice or humans.

METHODS

We evaluated the TGFβ-blocking antibody NIS793 in combination with gemcitabine/nanoparticle (albumin-bound)-paclitaxel or FOLFIRINOX (folinic acid [FOL], 5-fluorouracil [F], irinotecan [IRI] and oxaliplatin [OX]) in orthotopic pancreatic cancer models. Single-cell RNA sequencing and immunofluorescence were used to evaluate changes in tumor cell state and the tumor microenvironment.

RESULTS

Blockade of TGFβ with chemotherapy reduced tumor burden in poorly immunogenic pancreatic cancer, without affecting the metastatic rate of cancer cells. Efficacy of combination therapy was not dependent on CD8 T cells, because response to TGFβ blockade was preserved in CD8-depleted or recombination activating gene 2 (RAG2-/-) mice. TGFβ blockade decreased total α-smooth muscle actin-positive fibroblasts but had minimal effect on fibroblast heterogeneity. Bulk RNA sequencing on tumor cells sorted ex vivo revealed that tumor cells treated with TGFβ blockade adopted a classical lineage consistent with enhanced chemosensitivity, and immunofluorescence for cleaved caspase 3 confirmed that TGFβ blockade increased chemotherapy-induced cell death in vivo.

CONCLUSIONS

TGFβ regulates pancreatic cancer cell plasticity between classical and basal cell states. TGFβ blockade in orthotropic models of pancreatic cancer enhances sensitivity to chemotherapy by promoting a classical malignant cell state. This study provides scientific rationale for evaluation of NIS793 with FOLFIRINOX or gemcitabine/nanoparticle (albumin-bound) paclitaxel chemotherapy backbone in the clinical setting and supports the concept of manipulating cancer cell plasticity to increase the efficacy of combination therapy regimens.

Combined PD-L1/TGFβ blockade allows expansion and differentiation of stem cell-like CD8 T cells in immune excluded tumors

TGFβ signaling is associated with non-response to immune checkpoint blockade in patients with advanced cancers, particularly in the immune-excluded phenotype. While previous work demonstrates that converting tumors from excluded to inflamed phenotypes requires attenuation of PD-L1 and TGFβ signaling, the underlying cellular mechanisms remain unclear. Here, we show that TGFβ and PD-L1 restrain intratumoral stem cell-like CD8 T cell (TSCL) expansion and replacement of progenitor-exhausted and dysfunctional CD8 T cells with non-exhausted T effector cells in the EMT6 tumor model in female mice. Upon combined TGFβ/PD-L1 blockade IFNγhi CD8 T effector cells show enhanced motility and accumulate in the tumor. Ensuing IFNγ signaling transforms myeloid, stromal, and tumor niches to yield an immune-supportive ecosystem. Blocking IFNγ abolishes the anti-PD-L1/anti-TGFβ therapy efficacy. Our data suggest that TGFβ works with PD-L1 to prevent TSCL expansion and replacement of exhausted CD8 T cells, thereby maintaining the T cell compartment in a dysfunctional state.

Chimeric antigen receptor-modified T cells therapy in prostate cancer: A comprehensive review on the current state and prospects

Recent immunotherapy research has focused on chimeric antigen receptor-modified T cells (CAR-Ts). CAR-T therapies have been clinically applied to manage hematologic malignancies with satisfactory effectiveness. However, the application of CAR-T immunotherapy in solid tumors remains challenging. Even so, current CAR-T immunotherapies for prostate cancer (PCa) have shown some promise, giving hope to patients with advanced metastatic PCa. This review aimed to elucidate different types of prostate tumor-associated antigen targets, such as prostate-specific membrane antigen and prostate stem cell antigen, and their effects. The current status of the corresponding targets in clinical research through their applications was also discussed. To improve the efficacy of CAR-T immunotherapy, we addressed the possible applications of multimodal immunotherapy, chemotherapy, and CAR-T combined therapies. The obstacles of solid tumors were concisely elaborated. Further studies should aim to discover novel potential targets and establish new models by overcoming the inherent barriers of solid tumors, such as tumor heterogeneity and the immunosuppressive nature of the tumor microenvironment.

TGF-β broadly modifies rather than specifically suppresses reactivated memory CD8 T cells in a dose-dependent manner

Transforming growth factor β (TGF-β) directly acts on naïve, effector and memory T cells to control cell fate decisions, which was shown using genetic abrogation of TGF-β signaling. TGF-β availability is altered by infections and cancer, however the dose-dependent effects of TGF-β on memory CD8 T cell (Tmem) reactivation are still poorly defined. We examined how activation and TGF-β signals interact to shape the functional outcome of Tmem reactivation. We found that TGF-β could suppress cytotoxicity in a manner that was inversely proportional to the strength of the activating TCR or pro-inflammatory signals. In contrast, even high doses of TGF-β had a comparatively modest effect on IFN-γ expression in the context of weak and strong reactivation signals. Since CD8 Tmem may not always receive TGF-β signals concurrently with reactivation, we also explored whether the temporal order of reactivation versus TGF-β signals is of importance. We found that exposure to TGF-β prior to as well as after an activation event were both sufficient to reduce cytotoxic effector function. Concurrent ATAC-seq and RNA-seq analysis revealed that TGF-β altered ~10% of the regulatory elements induced by reactivation and also elicited transcriptional changes indicative of broadly modulated functional properties. We confirmed some changes on the protein level and found that TGF-β-induced expression of CCR8 was inversely proportional to the strength of the reactivating TCR signal. Together, our data suggest that TGF-β is not simply suppressing CD8 Tmem, but modifies functional and chemotactic properties in context of their reactivation signals and in a dose-dependent manner.

From barriers to novel strategies: smarter CAR T therapy hits hard to tumors

Chimeric antigen receptor (CAR) T cell therapy for solid tumors shows promise, but several hurdles remain. Strategies to overcome barriers such as CAR T therapy-related toxicities (CTT), immunosuppression, and immune checkpoints through research and technology are needed to put the last nail to the coffin and offer hope for previously incurable malignancies. Herein we review current literature and infer novel strategies for the mitigation of CTT while impeding immune suppression, stromal barriers, tumor heterogeneity, on-target/off-tumor toxicities, and better transfection strategies with an emphasis on clinical research and prospects.

The immunogenic radiation and new players in immunotherapy and targeted therapy for head and neck cancer

Although treatment modalities for head and neck cancer have evolved considerably over the past decades, survival rates have plateaued. The treatment options remained limited to definitive surgery, surgery followed by fractionated radiotherapy with optional chemotherapy, and a definitive combination of fractionated radiotherapy and chemotherapy. Lately, immunotherapy has been introduced as the fourth modality of treatment, mainly administered as a single checkpoint inhibitor for recurrent or metastatic disease. While other regimens and combinations of immunotherapy and targeted therapy are being tested in clinical trials, adapting the appropriate regimens to patients and predicting their outcomes have yet to reach the clinical setting. Radiotherapy is mainly regarded as a means to target cancer cells while minimizing the unwanted peripheral effect. Radiotherapy regimens and fractionation are designed to serve this purpose, while the systemic effect of radiation on the immune response is rarely considered a factor while designing treatment. To bridge this gap, this review will highlight the effect of radiotherapy on the tumor microenvironment locally, and the immune response systemically. We will review the methodology to identify potential targets for therapy in the tumor microenvironment and the scientific basis for combining targeted therapy and radiotherapy. We will describe a current experience in preclinical models to test these combinations and propose how challenges in this realm may be faced. We will review new players in targeted therapy and their utilization to drive immunogenic response against head and neck cancer. We will outline the factors contributing to head and neck cancer heterogeneity and their effect on the response to radiotherapy. We will review in-silico methods to decipher intertumoral and intratumoral heterogeneity and how these algorithms can predict treatment outcomes. We propose that (a) the sequence of surgery, radiotherapy, chemotherapy, and targeted therapy should be designed not only to annul cancer directly, but to prime the immune response. (b) Fractionation of radiotherapy and the extent of the irradiated field should facilitate systemic immunity to develop. (c) New players in targeted therapy should be evaluated in translational studies toward clinical trials. (d) Head and neck cancer treatment should be personalized according to patients and tumor-specific factors.

The diverse effects of transforming growth factor-β and SMAD signaling pathways during the CTL response

Cytotoxic T lymphocytes (CTLs) play an important role in defense against infections with intracellular pathogens and anti-tumor immunity. Efficient migration is required to locate and destroy infected cells in different regions of the body. CTLs accomplish this task by differentiating into specialized subsets of effector and memory CD8 T cells that traffic to different tissues. Transforming growth factor-beta (TGFβ) belongs to a large family of growth factors that elicit diverse cellular responses via canonical and non-canonical signaling pathways. Canonical SMAD-dependent signaling pathways are required to coordinate changes in homing receptor expression as CTLs traffic between different tissues. In this review, we discuss the various ways that TGFβ and SMAD-dependent signaling pathways shape the cellular immune response and transcriptional programming of newly activated CTLs. As protective immunity requires access to the circulation, emphasis is placed on cellular processes that are required for cell-migration through the vasculature.

Mechanistic rationales for combining immunotherapy with radiotherapy

Immunotherapy consisted mainly of immune checkpoint inhibitors (ICIs) has led to significantly improved antitumor response. However, such response has been observed only in tumors possessing an overall responsive tumor immune micro-environment (TIME), in which the presence of functional tumor-infiltrating lymphocytes (TILs) is critical. Various mechanisms of immune escape from immunosurveillance exist, leading to different TIME phenotypes in correlation with primary or acquired resistance to ICIs. Radiotherapy has been shown to induce antitumor immunity not only in the irradiated primary tumor, but also at unirradiated distant sites of metastases. Such antitumor immunity is mainly elicited by radiation's stimulatory effects on antigenicity and adjuvanticity. Furthermore, it may be significantly augmented when irradiation is combined with immunotherapy, such as ICIs. Therefore, radiotherapy represents one potential therapeutic strategy to restore anti-tumor immunity in tumors presenting with an unresponsive TIME. In this review, the generation of anti-tumor immunity, its impairment, radiation's immunogenic properties, and the antitumor effects of combining radiation with immunotherapy will be comprehensively discussed.

TGFβ control of immune responses in cancer: a holistic immuno-oncology perspective

The immune system responds to cancer in two main ways. First, there are prewired responses involving myeloid cells, innate lymphocytes and innate-like adaptive lymphocytes that either reside in premalignant tissues or migrate directly to tumours, and second, there are antigen priming-dependent responses, in which adaptive lymphocytes are primed in secondary lymphoid organs before homing to tumours. Transforming growth factor-β (TGFβ) - one of the most potent and pleiotropic regulatory cytokines - controls almost every stage of the tumour-elicited immune response, from leukocyte development in primary lymphoid organs to their priming in secondary lymphoid organs and their effector functions in the tumour itself. The complexity of TGFβ-regulated immune cell circuitries, as well as the contextual roles of TGFβ signalling in cancer cells and tumour stromal cells, necessitates the use of rigorous experimental systems that closely recapitulate human cancer, such as autochthonous tumour models, to uncover the underlying immunobiology. The diverse functions of TGFβ in healthy tissues further complicate the search for effective and safe cancer therapeutics targeting the TGFβ pathway. Here we discuss the contextual complexity of TGFβ signalling in tumour-elicited immune responses and explain how understanding this may guide the development of mechanism-based cancer immunotherapy.

Targeting CXCL9/10/11-CXCR3 axis: an important component of tumor-promoting and antitumor immunity

Chemokines are chemotactic-competent molecules composed of a family of small cytokines, playing a key role in regulating tumor progression. The roles of chemokines in antitumor immune responses are of great interest. CXCL9, CXCL10, and CXCL11 are important members of chemokines. It has been widely investigated that these three chemokines can bind to their common receptor CXCR3 and regulate the differentiation, migration, and tumor infiltration of immune cells, directly or indirectly affecting tumor growth and metastasis. Here, we summarize the mechanism of how the CXCL9/10/11-CXCR3 axis affects the tumor microenvironment, and list the latest researches to find out how this axis predicts the prognosis of different cancers. In addition, immunotherapy improves the survival of tumor patients, but some patients show drug resistance. Studies have found that the regulation of CXCL9/10/11-CXCR3 on the tumor microenvironment is involved in the process of changing immunotherapy resistance. Here we also describe new approaches to restoring sensitivity to immune checkpoint inhibitors through the CXCL9/10/11-CXCR3 axis.

The histone demethylase Utx controls CD8+ T-cell-dependent antitumor immunity via epigenetic regulation of the effector function

CD8⁺ T cells play a central role in antitumor immune responses. Epigenetic gene regulation is essential to acquire the effector function of CD8⁺ T cells. However, the role of Utx, a demethylase of histone H3K27, in antitumor immunity remains unclear. In this study, we examined the roles of Utx in effector CD8⁺ T-cell differentiation and the antitumor immune response. In a murine tumor-bearing model, an increased tumor size and decreased survival rate were observed in T-cell-specific Utx KO (Utx KO) mice compared with wild-type (WT) mice. The number of CD8⁺ T cells in tumor-infiltrating lymphocytes (TILs) was significantly decreased in Utx KO mice. We found that the acquisition of effector function was delayed and attenuated in Utx KO CD8⁺ T cells. RNA sequencing revealed that the expression of effector signature genes was decreased in Utx KO effector CD8⁺ T cells, while the expression of naïve or memory signature genes was increased. Furthermore, the expression of Cxcr3, which is required for the migration of effector CD8⁺ T cells to tumor sites, was substantially decreased in Utx KO CD8⁺ T cells. These findings suggest that Utx promotes CD8⁺ T-cell-dependent antitumor immune responses partially through epigenetic regulation of the effector function.

The role of dendritic cells in radiation-induced immune responses

Dendritic cells perform critical functions in bridging innate and adaptive immunity. Their ability to sense adjuvant signals in their environment, migrate on maturation, and cross-present cell-associated antigens enables these cells to carry antigen from tissue sites to lymph nodes, and thereby prime naïve T cells that cannot enter tissues. Despite being an infrequent cell type in tumors, we discuss how dendritic cells impact the immune environment of tumors and their response to cancer therapies. We review how radiation therapy of tumors can impact dendritic cells, through transfer of cell associated antigens to dendritic cells and the release of endogenous adjuvants, resulting in increased antigen presentation in the tumor-draining lymph nodes. We explore how tumor specific factors can result in negative regulation of dendritic cell function in the tumor, and the impact of direct radiation exposure to dendritic cells in the treatment field. These data suggest an important role for dendritic cell subpopulations in activating new T cell responses and boosting existing T cell responses to tumor associated antigens in tumor draining lymph nodes following radiation therapy. It further justifies a focus on the needs of the lymph node T cells to improve systemic anti-immunity following radiation therapy.

Mesoporous nanodrug delivery system: a powerful tool for a new paradigm of remodeling of the tumor microenvironment

Tumor microenvironment (TME) plays an important role in tumor progression, metastasis and therapy resistance. Remodeling the TME has recently been deemed an attractive tumor therapeutic strategy. Due to its complexity and heterogeneity, remodeling the TME still faces great challenges. With the great advantage of drug loading ability, tumor accumulation, multifactor controllability, and persistent guest molecule release ability, mesoporous nanodrug delivery systems (MNDDSs) have been widely used as effective antitumor drug delivery tools as well as remolding TME. This review summarizes the components and characteristics of the TME, as well as the crosstalk between the TME and cancer cells and focuses on the important role of drug delivery strategies based on MNDDSs in targeted remodeling TME metabolic and synergistic anticancer therapy.

TGF-β blocking combined with photothermal therapy promote tumor targeted migration and long-term antitumor activity of CAR-T cells

TGF-β is widely existed in tumor microenvironment, taking part in tumorigenesis process including angiogenesis, cancer associated fibroblast (CAF) proliferation, and immunosuppression. It inhibited the activation, proliferation, migration and differentiation of T cells, in which way caused a limited therapeutic effects of chimeric antigen receptor T (CAR-T) towards solid tumor such as lymphoma. To targeted block TGF-β at tumor site, we take advantages of nano-techniques to deliver TGF-β inhibitors LY2157299 (LY) towards the tumor sites, in order to help achieve a improved and long-term functions of CAR-T towards lymphoma. Based on amphipathic hydroxyethyl starch-polycaprolactone (HES-PCL), LY and photosensitizer indocyanine green (ICG) were co-loaded in HES-PCL to achieve LY/ICG@HES-PCL nanoparticle. The enhanced function of CAR-T benefited from LY/ICG@HES-PCL were verified through lymphoma Raji cells in vitro and Nod scid gamma mice engrafted with the Raji cells in vivo. LY was targeted transported to tumor site and accelerated release by mild ICG photothermal. Chemokines CXCL9/10/11 ​at the tumor site relevant to CAR-T migration and chemokines receptor CXCR3 of CAR-T could be up-regulated by LY, thus facilitated the enhanced accumulation of CAR-T at lymphoma site. T effector memory cells differentiation could also be accelerated by LY/ICG@HES-PCL. Combined therapy of LY/ICG@HES-PCL and CAR-T achieved 2.4 times higher antitumor activity and 2.7 times higher relapse inhibiting rates than CAR-T alone within 15 days and 11 days, respectively. The results suggested that LY/ICG@HES-PCL facilitated the enhanced therapeutic index of CAR-T cells towards lymphoma simply and safely, it may be further potentiated applied for other solid tumors.

Resistance to immune checkpoint inhibitors and the tumor microenvironment

Immune checkpoint inhibitors (ICIs) have contributed significantly to the treatment of various types of cancer, including skin cancer. However, not all patients respond; some patients do not respond at all (primary resistance), while others experience recurrence after the initial response (acquired resistance). Therefore, overcoming ICI resistance is an urgent priority. Numerous ICI resistance mechanisms have been reported. They are seemingly quite complex, varying from patient to patient. However, most involve T-cell activation processes, especially in the tumor microenvironment (TME). ICIs exert their effects in the TME by reactivating suppressed T cells through inhibition of immune checkpoint molecules, such as cytotoxic T-lymphocyte antigen-4 (CTLA-4) and programmed cell death protein 1 (PD-1). Thus, this review focuses on the resistance mechanisms based on the T-cell activation process. Here, we classify the main mechanisms of ICI resistance into three categories based on (1) antigen recognition, (2) T-cell migration and infiltration, and (3) effector functions of T cells. By identifying and understanding these resistance mechanisms individually, including unknown mechanisms, we seek to contribute to the development of novel treatments to overcome ICI resistance.

CXCR3 Expression Is Associated with Advanced Tumor Stage and Grade Influencing Survival after Surgery of Localised Renal Cell Carcinoma

BACKGROUND

Surgery is the standard treatment in localized renal cell carcinoma (RCC). Pembrolizumab is now approved for adjuvant therapy in high-risk patients. However, inhomogeneity of studies gives ambiguity which patient benefit most from adjuvant therapy. A high infiltration of CD8⁺ T cells is known to be linked with poor prognosis in RCC. CXCR3 is a key player of CD8⁺ T cell differentiation and infiltration. We aimed to evaluate CXCR3 as a potential marker for predicting recurrence.

METHODS

CXCR3 and immune cell subsets (CD4, CD8, CD68 and FoXP3) were measured on RCC samples by multiplex immunofluorescence (mIF) staining. Cellular localization of CXCR3 was evaluated using single-cell RNA analysis on a publicly available dataset.

RESULTS

Tumor samples of 42 RCC patients were analyzed, from which 59.5% were classified as clear-cell RCC and of which 20 had recurrence. Single-cell RNA analysis revealed that CXCR3 was predominantly expressed in intratumoral T cells and dendritic cells. CXCR3 expression was higher in advanced tumors stages (p = 0.0044) and grade (p = 0.0518), correlating significantly with a higher CD8⁺ T cell expression (p < 0.001). Patients with CXCR3^high RCCs had also a significant shorter RFS compared to CXCR3^low (median: 78 vs. 147 months, p = 0.0213). In addition, also tumor stage pT3/4 (p < 0.0001) as well as grade G3/4 (p = 0.0008) negatively influenced RFS.

CONCLUSION

CXCR3^high cell density was associated with high T cell infiltration and advanced tumor stage, worsening RFS in surgically resected RCC patients. Beside its prognostic value, CXCR3 might be a predictive biomarker to guide therapy decision for adjuvant therapy in localized RCC.

Rebalancing TGFβ1/BMP signals in exhausted T cells unlocks responsiveness to immune checkpoint blockade therapy

T cell dysfunctionality prevents the clearance of chronic infections and cancer. Furthermore, epigenetic programming in dysfunctional CD8+ T cells limits their response to immunotherapies, including immune checkpoint blockade (ICB). However, it is unclear which upstream signals drive acquisition of dysfunctional epigenetic programs, and whether therapeutically targeting these signals can remodel terminally dysfunctional T cells to an ICB-responsive state. Here we innovate an in vitro model system of stable human T cell dysfunction and show that chronic TGFβ1 signaling in posteffector CD8+ T cells accelerates their terminal dysfunction through stable epigenetic changes. Conversely, boosting bone morphogenetic protein (BMP) signaling while blocking TGFβ1 preserved effector and memory programs in chronically stimulated human CD8+ T cells, inducing superior responses to tumors and synergizing the ICB responses during chronic viral infection. Thus, rebalancing TGFβ1/BMP signals provides an exciting new approach to unleash dysfunctional CD8+ T cells and enhance T cell immunotherapies.

Hypoxia induced lactate acidosis modulates tumor microenvironment and lipid reprogramming to sustain the cancer cell survival

It is well known that solid hypoxic tumour cells oxidise glucose through glycolysis, and the end product of this pathway is fermented into lactate which accumulates in the tumour microenvironment (TME). Initially, it was proclaimed that cancer cells cannot use lactate; therefore, they dump it into the TME and subsequently augment the acidity of the tumour milieu. Furthermore, the TME acts as a lactate sink with stope variable amount of lactate in different pathophysiological condition. Regardless of the amount of lactate pumped out within TME, it disappears immediately which still remains an unresolved puzzle. Recent findings have paved pathway in exploring the main role of lactate acidosis in TME. Cancer cells utilise lactate in the de novo fatty acid synthesis pathway to initiate angiogenesis and invasiveness, and lactate also plays a crucial role in the suppression of immunity. Furthermore, lactate re-programme the lipid biosynthetic pathway to develop a metabolic symbiosis in normoxic, moderately hypoxic and severely hypoxic cancer cells. For instance: severely hypoxic cancer cells enable to synthesizing poly unsaturated fatty acids (PUFA) in oxygen scarcity secretes excess of lactate in TME. Lactate from TME is taken up by the normoxic cancer cells whereas it is converted back to PUFAs after a sequence of reactions and then liberated in the TME to be utilized in the severely hypoxic cancer cells. Although much is known about the role of lactate in these biological processes, the exact molecular pathways that are involved remain unclear. This review attempts to understand the molecular pathways exploited by lactate to initiate angiogenesis, invasiveness, suppression of immunity and cause re-programming of lipid synthesis. This review will help the researchers to develop proper understanding of lactate associated bimodal regulations of TME.

Manipulation of metabolic pathways to promote stem-like and memory T cell phenotypes for immunotherapy

Utilizing the immune system's capacity to recognize and kill tumor cells has revolutionized cancer therapy in recent decades. Phenotypic study of antitumor T cells supports the principle that superior tumor control is achieved by cells with more long-lived memory or stem-like properties as compared to terminally differentiated effector cells. In this Mini-Review, we explore recent advances in profiling the different metabolic programs that both generate and define subsets of memory T cells. We additionally discuss new experimental approaches that aim to maximize the durability and sustained antitumor response associated with memory T cells within the unique immunosuppressive conditions of the tumor microenvironment, such as engineered attempts to overcome hypoxia-induced changes in mitochondrial function, the inhibitory effects of tumor metabolites, and exploitation of more recently-defined metabolic pathways controlling T cell memory fate such as glycogen metabolism.

Molecular and therapeutic effect of CRISPR in treating cancer

Cancer has become one of the common causes of mortality around the globe due to mutations in the genome which allows rapid growth of cells uncontrollably without repairing DNA errors. Cancers could arise due alterations in DNA repair mechanisms (errors in mismatch repair genes), activation of oncogenes and inactivation of tumor suppressor genes. Each cancer type is different and each individual has a unique genetic change which leads them to cancer. Studying genetic and epigenetic alterations in the genome leads to understanding the underlying features. CAR T therapy over other immunotherapies such as monoclonal antibodies, immune checkpoint inhibitors, cancer vaccines and adoptive cell therapies has been widely used to treat cancer in recent days and gene editing has now become one of the promising treatments for many genetic diseases. This tool allows scientists to change the genome by adding, removing or altering genetic material of an organism. Due to advance in genetics and novel molecular techniques such as CRISPR, TALEN these genes can be edited in such a way that their original function could be replaced which in turn improved the treatment possibilities and can be used against malignancies and even cure cancer in future along with CAR T cell therapy due to the specific recognition and attacking of tumor.

Late-stage MC38 tumours recapitulate features of human colorectal cancer - implications for appropriate timepoint selection in preclinical studies

Anti-tumour T cell responses play a crucial role in controlling the progression of colorectal cancer (CRC), making this disease a promising candidate for immunotherapy. However, responses to immune-targeted therapies are currently limited to subpopulations of patients and specific types of cancer. Clinical studies have therefore focussed on identifying biomarkers that predict immunotherapy responses and elucidating the immunological landscapes of different cancers. Meanwhile, our understanding of how preclinical tumour models resemble human disease has fallen behind, despite their crucial role in immune-targeted drug development. A deeper understanding of these models is therefore needed to improve the development of immunotherapies and the translation of findings made in these systems. MC38 colon adenocarcinoma is a widely used preclinical model, yet how it recapitulates human colorectal cancer remains poorly defined. This study investigated the tumour-T cell immune landscape of MC38 tumours using histology, immunohistochemistry, and flow cytometry. We demonstrate that early-stage tumours exhibit a nascent TME, lacking important immune-resistance mechanisms of clinical interest, while late-stage tumours exhibit a mature TME resembling human tumours, with desmoplasia, T cell exhaustion, and T cell exclusion. Consequently, these findings clarify appropriate timepoint selection in the MC38 model when investigating both immunotherapies and mechanisms that contribute to immunotherapy resistance. Overall, this study provides a valuable resource that will enable appropriate application of the MC38 model and expedite the development and clinical translation of new immunotherapies.

Targeting TGF-β signaling in the multiple myeloma microenvironment: Steering CARs and T cells in the right direction

Multiple myeloma (MM) remains a lethal hematologic cancer characterized by the expansion of transformed plasma cells within the permissive bone marrow (BM) milieu. The emergence of relapsed and/or refractory MM (RRMM) is provoked through clonal evolution of malignant plasma cells that harbor genomic, metabolic and proteomic perturbations. For most patients, relapsed disease remains a major cause of overall mortality. Transforming growth factors (TGFs) have pleiotropic effects that regulate myelomagenesis as well as the emergence of drug resistance. Moreover, TGF-β modulates numerous cell types present with the tumor microenvironment, including many immune cell types. While numerous agents have been FDA-approved over the past 2 decades and significantly expanded the treatment options available for MM patients, the molecular mechanisms responsible for drug resistance remain elusive. Multiple myeloma is uniformly preceded by a premalignant state, monoclonal gammopathy of unknown significance, and both conditions are associated with progressive deregulation in host immunity characterized by reduced T cell, natural killer (NK) cell and antigen-presenting dendritic cell (DC) activity. TGF-β promotes myelomagenesis as well as intrinsic drug resistance by repressing anti-myeloma immunity to promote tolerance, drug resistance and disease progression. Hence, repression of TGF-β signaling is a prerequisite to enhance the efficacy of current and future immunotherapeutics. Novel strategies that incorporate T cells that have been modified to express chimeric antigen receptor (CARs), T cell receptors (TCRs) and bispecific T cell engagers (BiTEs) offer promise to block TGF-β signaling, overcome chemoresistance and enhance anti-myeloma immunity. Here, we describe the effects of TGF-β signaling on immune cell effectors in the bone marrow and emerging strategies to overcome TGF-β-mediated myeloma growth, drug resistance and survival.

Multifunctional mRNA-Based CAR T Cells Display Promising Antitumor Activity Against Glioblastoma

PURPOSE

Most chimeric antigen receptor (CAR) T-cell strategies against glioblastoma have demonstrated only modest therapeutic activity and are based on persistent gene modification strategies that have limited transgene capacity, long manufacturing processes, and the risk for uncontrollable off-tumor toxicities. mRNA-based T-cell modifications are an emerging safe, rapid, and cost-effective alternative to overcome these challenges, but are underexplored against glioblastoma.

EXPERIMENTAL DESIGN

We generated mouse and human mRNA-based multifunctional T cells coexpressing a multitargeting CAR based on the natural killer group 2D (NKG2D) receptor and the proinflammatory cytokines IL12 and IFNα2 and assessed their antiglioma activity in vitro and in vivo.

RESULTS

Compared with T cells that either expressed the CAR or cytokines alone, multifunctional CAR T cells demonstrated increased antiglioma activity in vitro and in vivo in three orthotopic immunocompetent mouse glioma models without signs of toxicity. Mechanistically, the coexpression of IL12 and IFNα2 in addition to the CAR promoted a proinflammatory tumor microenvironment and reduced T-cell exhaustion as demonstrated by ex vivo immune phenotyping, cytokine profiling, and RNA sequencing. The translational potential was demonstrated by image-based single-cell analyses of mRNA-modified T cells in patient glioblastoma samples with a complex cellular microenvironment. This revealed strong antiglioma activity of human mRNA-based multifunctional NKG2D CAR T cells coexpressing IL12 and IFNα2 whereas T cells that expressed either the CAR or cytokines alone did not demonstrate comparable antiglioma activity.

CONCLUSIONS

These data provide a robust rationale for future clinical studies with mRNA-based multifunctional CAR T cells to treat malignant brain tumors.

Bidirectional crosstalk between epithelial-mesenchymal plasticity and IFNγ-induced PD-L1 expression promotes tumour progression

Epithelial-mesenchymal transition (EMT) and immunoevasion through upregulation of programmed death-ligand 1 (PD-L1) are important drivers of cancer progression. While EMT has been proposed to facilitate PD-L1-mediated immunosuppression, molecular mechanisms of their interaction remain obscure. Here, we provide insight into these mechanisms by proposing a mathematical model that describes the crosstalk between EMT and interferon gamma (IFNγ)-induced PD-L1 expression. Our model shows that via interaction with microRNA-200 (miR-200), the multi-stability of the EMT regulatory circuit is mirrored in PD-L1 levels, which are further amplified by IFNγ stimulation. This IFNγ-mediated effect is most prominent for cells in a fully mesenchymal state and less strong for those in an epithelial or partially mesenchymal state. In addition, bidirectional crosstalk between miR-200 and PD-L1 implies that IFNγ stimulation allows cells to undergo EMT for lower amounts of inducing signal, and the presence of IFNγ accelerates EMT and decelerates mesenchymal-epithelial transition (MET). Overall, our model agrees with published findings and provides insight into possible mechanisms behind EMT-mediated immune evasion, and primary, adaptive, or acquired resistance to immunotherapy. Our model can be used as a starting point to explore additional crosstalk mechanisms, as an improved understanding of these mechanisms is indispensable for developing better diagnostic and therapeutic options for cancer patients.

Migratory Engineering of T Cells for Cancer Therapy

Adoptive cell therapy (ACT) and chimeric antigen receptor (CAR) T cell therapy in particular represents an adaptive, yet versatile strategy for cancer treatment. Convincing results in the treatment of hematological malignancies have led to FDA approval for several CAR T cell therapies in defined refractory diseases. In contrast, the treatment of solid tumors with adoptively transferred T cells has not demonstrated convincing efficacy in clinical trials. One of the main reasons for ACT failure in solid tumors is poor trafficking or access of transferred T cells to the tumor site. Tumors employ a variety of mechanisms shielding themselves from immune cell infiltrates, often translating to only fractions of transferred T cells reaching the tumor site. To overcome this bottleneck, extensive efforts are being undertaken at engineering T cells to improve ACT access to solid tumors. In this review, we provide an overview of the immune cell infiltrate in human tumors and the mechanisms tumors employ toward immune exclusion. We will discuss ways in which T cells can be engineered to circumvent these barriers. We give an outlook on ongoing clinical trials targeting immune cell migration to improve ACT and its perspective in solid tumors.

Multiplexed In Situ Spatial Protein Profiling in the Pursuit of Precision Immuno-Oncology for Patients with Breast Cancer

Immune checkpoint inhibitors (ICIs) have revolutionized the treatment of many solid tumors. In breast cancer (BC), immunotherapy is currently approved in combination with chemotherapy, albeit only in triple-negative breast cancer. Unfortunately, most patients only derive limited benefit from ICIs, progressing either upfront or after an initial response. Therapeutics must engage with a heterogeneous network of complex stromal-cancer interactions that can fail at imposing cancer immune control in multiple domains, such as in the genomic, epigenomic, transcriptomic, proteomic, and metabolomic domains. To overcome these types of heterogeneous resistance phenotypes, several combinatorial strategies are underway. Still, they can be predicted to be effective only in the subgroups of patients in which those specific resistance mechanisms are effectively in place. As single biomarker predictive performances are necessarily suboptimal at capturing the complexity of this articulate network, precision immune-oncology calls for multi-omics tumor microenvironment profiling in order to identify unique predictive patterns and to proactively tailor combinatorial treatments. Multiplexed single-cell spatially resolved tissue analysis, through precise epitope colocalization, allows one to infer cellular functional states in view of their spatial organization. In this review, we discuss-through the lens of the cancer-immunity cycle-selected, established, and emerging markers that may be evaluated in multiplexed spatial protein panels to help identify prognostic and predictive patterns in BC.

Protein Tyrosine Kinase 7 (PTK7) Promotes Metastasis in Hepatocellular Carcinoma via SOX9 Regulation and TGF-β Signaling

BACKGROUND & AIMS

Metastasis is found in most advanced hepatocellular carcinoma (HCC) patients, and it drives tumor recurrence and systemic failure. There is no effective treatment owing to its complex biological features. Many of the molecular drivers of metastasis are crucial players in normal physiology but behave unconventionally during cancer progression. Targeting these molecular drivers for therapy and differentiating them from a physiological background require a detailed examination of the novel mechanisms involved in their activation during metastasis.

METHODS

Publicly available transcriptomic data such as that of TCGA-LIHC and Gene Expression Omnibus were utilized to identify novel targets upregulated in advanced and metastatic HCC. Validation of candidates was assisted by immunohistochemistry performed on tissue microarrays derived from more than 100 HCC patients. Expression of protein tyrosine kinase 7 (PTK7) was studied under the treatment of transforming growth factor-β1 and knockdown of SRY-Box Transcription Factor 9 (SOX9) to delineate upstream regulation, while CRISPR-mediated knockout and lentiviral overexpression of PTK7 in HCC cells were performed to study their functional and signaling consequences. Manipulated HCC cells were injected into mice models either by orthotopic or tail-vein injection to observe for any in vivo pro-metastatic effects.

RESULTS

PTK7 was discovered to be the kinase most significantly upregulated in advanced and metastatic HCC, at both transcriptomic and proteomic level. Bioinformatic analyses and functional assays performed in HCC cell lines revealed transforming growth factor-β signaling and SOX9 to be important activators of PTK7 expression. Functionally, enrichment of PTK7 expression could positively regulate metastatic potential of HCC cells in vitro and in lung metastasis models performed in immunodeficient mice. The up-regulation of PTK7 recruited the epithelial-mesenchymal transition components, zinc finger protein SNAI2 (SLUG) and zinc finger E-box-binding homeobox 1 (ZEB1).

CONCLUSIONS

Our study proposes PTK7 as a novel molecular driver in metastatic HCC, particularly in a transforming growth factor-β-activated microenvironment. The preferential expression of PTK7 resulted in a previously unobserved regulatory effect on the recruitment of epithelial-mesenchymal transition components, which established PTK7 as a potential determinant of specific epithelial-mesenchymal transition status. Therefore, our data support the continual development of PTK7-targeted agents as antimetastatic therapies.

Moving beyond the T cell synapse for combination neoadjuvant immunotherapy in head and neck cancer

Patients with HPV-unrelated head and neck squamous cell carcinoma (HPV-unrelated HNSCC) show only modest benefit from treatment with PD-1 inhibitors (PD-1i). Targeting transforming growth factor β (TGF-β) may make PD-1i more effective by inducing T cell responses. In this issue of the JCI, Redman et al. performed a clinical trial in 14 patients with HPV-unrelated HNSCC using bintrafusp alfa, a bifunctional fusion protein that blocks PD-L1 and TGF-β. Primary tumors displayed pathologic responses with 5 of 14 patients having at least a partial response. While no primary tumor or metastatic lymph node demonstrated a complete pathologic response, the findings suggest that concurrent neoadjuvant inhibition of PD-L1 and TGF-β may provide a rational strategy to improve pathologic response and clinical outcome in patients with HPV-unrelated HNSCC.

Novel Cocktail Therapy Based on a Nanocarrier with an Efficient Transcytosis Property Reverses the Dynamically Deteriorating Tumor Microenvironment for Enhanced Immunotherapy

The immune checkpoint blockade (ICB) faces a low response rate in clinical cancer treatment. Chemotherapy could enhance the response rate of the ICB, but patients would suffer from side effects. The off-target toxicity could be reduced by loading the chemotherapeutic agent through nanocarriers. Therefore, we developed a polymeric carrier for doxorubicin (DOX) loading to form DOX nanoparticles (DOX NPs), which were spatiotemporally responsive to the tumor microenvironment (TME). DOX NPs had an efficient transcytosis property for deep tumor infiltration and sustained drug release ability. Unfortunately, a binary therapy of DOX NPs and ICB induces tumor adaptive resistance and causes dynamic deterioration of the TME. We propose for the first time that TGF-β1 is a major cause of tumor adaptive resistance and developed an immune cocktail therapy containing DOX NPs, ICB, and TGF-β1 gene silencing nanoparticles. This therapy successfully overcame tumor adaptive resistance by reversing the immunosuppressive TME and achieved enhanced tumor treatment efficiency.

Selective targeting of GARP-LTGFβ axis in the tumor microenvironment augments PD-1 blockade via enhancing CD8+ T cell antitumor immunity

BACKGROUND

Immune checkpoint blockade (ICB) has revolutionized cancer immunotherapy. However, most patients with cancer fail to respond clinically. One potential reason is the accumulation of immunosuppressive transforming growth factor β (TGFβ) in the tumor microenvironment (TME). TGFβ drives cancer immune evasion in part by inducing regulatory T cells (Tregs) and limiting CD8+ T cell function. Glycoprotein-A repetitions predominant (GARP) is a cell surface docking receptor for activating latent TGFβ1, TGFβ2 and TGFβ3, with its expression restricted predominantly to effector Tregs, cancer cells, and platelets.

METHODS

We investigated the role of GARP in human patients with cancer by analyzing existing large databases. In addition, we generated and humanized an anti-GARP monoclonal antibody and evaluated its antitumor efficacy and underlying mechanisms of action in murine models of cancer.

RESULTS

We demonstrate that GARP overexpression in human cancers correlates with a tolerogenic TME and poor clinical response to ICB, suggesting GARP blockade may improve cancer immunotherapy. We report on a unique anti-human GARP antibody (named PIIO-1) that specifically binds the ligand-interacting domain of all latent TGFβ isoforms. PIIO-1 lacks recognition of GARP-TGFβ complex on platelets. Using human LRRC32 (encoding GARP) knock-in mice, we find that PIIO-1 does not cause thrombocytopenia; is preferentially distributed in the TME; and exhibits therapeutic efficacy against GARP+ and GARP- cancers, alone or in combination with anti-PD-1 antibody. Mechanistically, PIIO-1 treatment reduces canonical TGFβ signaling in tumor-infiltrating immune cells, prevents T cell exhaustion, and enhances CD8+ T cell migration into the TME in a C-X-C motif chemokine receptor 3 (CXCR3)-dependent manner.

CONCLUSION

GARP contributes to multiple aspects of immune resistance in cancer. Anti-human GARP antibody PIIO-1 is an efficacious and safe strategy to block GARP-mediated LTGFβ activation, enhance CD8+ T cell trafficking and functionality in the tumor, and overcome primary resistance to anti-PD-1 ICB. PIIO-1 therefore warrants clinical development as a novel cancer immunotherapeutic.