Tigilanol tiglate is an oncolytic small molecule that induces immunogenic cell death and enhances the response of both target and non-injected tumors to immune checkpoint blockade.

BACKGROUND: Tigilanol tiglate (TT) is a protein kinase C (PKC)/C1 domain activator currently being developed as an intralesional agent for the treatment of various (sub)cutaneous malignancies. Previous work has shown that intratumoral (I.T.) injection of TT causes vascular disruption with concomitant tumor ablation in several preclinical models of cancer, in addition to various (sub)cutaneous tumors presenting in the veterinary clinic. TT has completed Phase I dose escalation trials, with some patients showing signs of abscopal effects. However, the exact molecular details underpinning its mechanism of action (MoA), together with its immunotherapeutic potential in oncology remain unclear. METHODS: A combination of microscopy, luciferase assays, immunofluorescence, immunoblotting, subcellular fractionation, intracellular ATP assays, phagocytosis assays and mixed lymphocyte reactions were used to probe the MoA of TT in vitro. In vivo studies with TT used MM649 xenograft, CT-26 and immune checkpoint inhibitor refractory B16-F10-OVA tumor bearing mice, the latter with or without anti-programmed cell death 1 (PD-1)/anti-cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) mAb treatment. The effect of TT at injected and non-injected tumors was also assessed. RESULTS: Here, we show that TT induces the death of endothelial and cancer cells at therapeutically relevant concentrations via a caspase/gasdermin E-dependent pyroptopic pathway. At therapeutic doses, our data demonstrate that TT acts as a lipotoxin, binding to and promoting mitochondrial/endoplasmic reticulum (ER) dysfunction (leading to unfolded protein responsemt/ER upregulation) with subsequent ATP depletion, organelle swelling, caspase activation, gasdermin E cleavage and induction of terminal necrosis. Consistent with binding to ER membranes, we found that TT treatment promoted activation of the integrated stress response together with the release/externalization of damage-associated molecular patterns (HMGB1, ATP, calreticulin) from cancer cells in vitro and in vivo, characteristics indicative of immunogenic cell death (ICD). Confirmation of ICD in vivo was obtained through vaccination and rechallenge experiments using CT-26 colon carcinoma tumor bearing mice. Furthermore, TT also reduced tumor volume, induced immune cell infiltration, as well as improved survival in B16-F10-OVA tumor bearing mice when combined with immune checkpoint blockade. CONCLUSIONS: These data demonstrate that TT is an oncolytic small molecule with multiple targets and confirms that cell death induced by this compound has the potential to augment antitumor responses to immunotherapy.

Novel peptide-based oncolytic vaccine for enhancement of adaptive antitumor immune response via co-engagement of innate Fcγ and Fcα receptors.

BACKGROUND: Cancer immunotherapy relies on using the immune system to recognize and eradicate cancer cells. Adaptive immunity, which consists of mainly antigen-specific cytotoxic T cells, plays a pivotal role in controlling cancer progression. However, innate immunity is a necessary component of the cancer immune response to support an immunomodulatory state, enabling T-cell immunosurveillance. METHODS: Here, we elucidated and exploited innate immune cells to sustain the generation of antigen-specific T cells on the use of our cancer vaccine platform. We explored a previously developed oncolytic adenovirus (AdCab) encoding for a PD-L1 (Programmed-Death Ligand 1) checkpoint inhibitor, which consists of a PD-1 (Programmed Cell Death Protein 1) ectodomain fused to an IgG/A cross-hybrid Fc. We coated AdCab with major histocompatibility complex (MHC-I)-restricted tumor peptides, generating a vaccine platform (named PeptiCab); the latter takes advantage of viral immunogenicity, peptide cancer specificity to prime T-cell responses, and antibody-mediated effector functions. RESULTS: As proof of concept, PeptiCab was used in murine models of melanoma and colon cancer, resulting in tumor growth control and generation of systemic T-cell-mediated antitumor responses. In specific, PeptiCab was able to generate antitumor T effector memory cells able to secrete various inflammatory cytokines. Moreover, PeptiCab was able to polarize neutrophils to attain an antigen-presenting phenotype by upregulating MHC-II, CD80 and CD86 resulting in an enhanced T-cell expansion. CONCLUSION: Our data suggest that exploiting innate immunity activates T-cell antitumor responses, enhancing the efficiency of a vaccine platform based on oncolytic adenovirus coated with MHC-I-restricted tumor peptides.

Metformin Alters Tumor Immune Microenvironment, Improving the Outcomes of Breast Cancer Patients With Type 2 Diabetes Mellitus.

This study investigated the clinical effect of metformin on breast cancer patients with preexisting type 2 diabetes mellitus (T2DM). We analyzed 177 patients with T2DM who underwent breast cancer surgery and assessed tumor-associated macrophages (TAMs) and tumor-infiltrating lymphocytes (TILs) in patients who underwent tumor resection with or without metformin treatment using multiplex immunohistochemistry (IHC). Patients who received metformin either pre- or postoperatively exhibited reduced distant organ recurrence and improved postoperative recurrence-free survival compared to those of patients who did not. Additionally, in a subgroup of 40 patients receiving preoperative systemic therapy, metformin treatment was associated with increased rates of pathological complete response. IHC analysis revealed significantly lower levels of cluster of differentiation (CD) 68(+) CD163(+) M2-type TAMs (p < 0.01) but higher CD3(+) and CD8(+) TIL densities in the metformin-treated group compared with the same parameters in those without metformin treatment, with a significant difference in the CD8(+)/CD3(+) TIL ratio (p < 0.01). Despite the constraints posed by our small sample size, our findings suggest a potential role for metformin in modulating the immunological microenvironment, which may contribute to improved outcomes in diabetes patients with breast cancer.

Inflamed immune phenotype predicts favorable clinical outcomes of immune checkpoint inhibitor therapy across multiple cancer types.

BACKGROUND: The inflamed immune phenotype (IIP), defined by enrichment of tumor-infiltrating lymphocytes (TILs) within intratumoral areas, is a promising tumor-agnostic biomarker of response to immune checkpoint inhibitor (ICI) therapy. However, it is challenging to define the IIP in an objective and reproducible manner during manual histopathologic examination. Here, we investigate artificial intelligence (AI)-based immune phenotypes capable of predicting ICI clinical outcomes in multiple solid tumor types. METHODS: Lunit SCOPE IO is a deep learning model which determines the immune phenotype of the tumor microenvironment based on TIL analysis. We evaluated the correlation between the IIP and ICI treatment outcomes in terms of objective response rates (ORR), progression-free survival (PFS), and overall survival (OS) in a cohort of 1,806 ICI-treated patients representing over 27 solid tumor types retrospectively collected from multiple institutions. RESULTS: We observed an overall IIP prevalence of 35.2% and significantly more favorable ORRs (26.3% vs 15.8%), PFS (median 5.3 vs 3.1 months, HR 0.68, 95% CI 0.61 to 0.76), and OS (median 25.3 vs 13.6 months, HR 0.66, 95% CI 0.57 to 0.75) after ICI therapy in IIP compared with non-IIP patients, respectively (p<0.001 for all comparisons). On subgroup analysis, the IIP was generally prognostic of favorable PFS across major patient subgroups, with the exception of the microsatellite unstable/mismatch repair deficient subgroup. CONCLUSION: The AI-based IIP may represent a practical, affordable, clinically actionable, and tumor-agnostic biomarker prognostic of ICI therapy response across diverse tumor types.

Efficacy and safety of autologous tumor-infiltrating lymphocytes in recurrent or refractory ovarian cancer, colorectal cancer, and pancreatic ductal adenocarcinoma.

BACKGROUND: Tumor-infiltrating lymphocyte (TIL) therapy has shown efficacy in metastatic melanoma, non-small cell lung cancer, and other solid tumors. Our preclinical work demonstrated more robust CD8 predominant TIL production when agonistic anti-4-1BB and CD3 antibodies were used in early ex vivo TIL culture. METHODS: Patients with treatment-refractory metastatic colorectal (CRC), pancreatic (PDAC) and ovarian (OVCA) cancers were eligible. Lymphodepleting chemotherapy was followed by infusion of ex vivo expanded TIL, manufactured at MD Anderson Cancer Center with IL-2 and agonistic stimulation of CD3 and 4-1BB (urelumab). Patients received up to six doses of high-dose IL-2 after TIL infusion. Primary endpoint was evaluation of objective response rate at 12 weeks using Response Evaluation Criteria in Solid Tumors version 1.1 with secondary endpoints including disease control rate (DCR), duration of response, progression-free survival (PFS), overall survival (OS), and safety. RESULTS: 17 patients underwent TIL harvest and 16 were treated on protocol (NCT03610490), including 8 CRC, 5 PDAC, and 3 OVCA patients. Median age was 57.5 (range 33-70) and 50% were females. Median number of lines of prior therapy was 2 (range 1-8). No responses were observed at 12 weeks. Ten subjects achieved at least one stable disease (SD) assessment for a DCR of 62.5% (95% CI 35.4% to 84.8%). Best response included prolonged SD in a patient with PDAC lasting 17 months. Median PFS and OS across cohorts were 2.53 months (95% CI 1.54 to 4.11) and 18.86 months (95% CI 4.86 to NR), respectively. Grade 3 or higher toxicities attributable to therapy were seen in 14 subjects (87.5%; 95% CI 61.7% to 98.4%). Infusion product analysis showed the presence of effector memory cells with high expression of CD39 irrespective of tumor type and low expression of checkpoint markers. CONCLUSIONS: TIL manufactured with assistance of 4-1BB and CD3 agonism is feasible and treatment is associated with no new safety signals. While no responses were observed, a significant portion of patients achieved SD suggesting early/partial immunological effect. Further research is required to identify factors associated with resistance and functionally enhance T cells for a more effective therapy.

Cell membrane-anchored and tumor-targeted IL-12 T-cell therapy destroys cancer-associated fibroblasts and disrupts extracellular matrix in heterogenous osteosarcoma xenograft models.

BACKGROUND: The extracellular matrix (ECM) and cancer-associated fibroblasts (CAFs) play major roles in tumor progression, metastasis, and the poor response of many solid tumors to immunotherapy. CAF-targeted chimeric antigen receptor-T cell therapy cannot infiltrate ECM-rich tumors such as osteosarcoma. METHOD: In this study, we used RNA sequencing to assess whether the recently invented membrane-anchored and tumor-targeted IL-12-armed (attIL12) T cells, which bind cell-surface vimentin (CSV) on tumor cells, could destroy CAFs to disrupt the ECM. We established an in vitro model of the interaction between osteosarcoma CAFs and attIL12-T cells to uncover the underlying mechanism by which attIL12-T cells penetrate stroma-enriched osteosarcoma tumors. RESULTS: RNA sequencing demonstrated that attIL12-T cell treatment altered ECM-related gene expression. Immunohistochemistry staining revealed disruption or elimination of high-density CAFs and ECM in osteosarcoma xenograft tumors following attIL12-T cell treatment, and CAF/ECM density was inversely correlated with T-cell infiltration. Other IL12-armed T cells, such as wild-type IL-12-targeted or tumor-targeted IL-12-T cells, did not disrupt the ECM because this effect depended on the engagement between CSV on the tumor cell and its ligand on the attIL12-T cells. Mechanistic studies found that attIL12-T cell treatment elevated IFNγ production on interacting with CSV+ tumor cells, suppressing transforming growth factor beta secretion and in turn upregulating FAS-mediated CAF apoptosis. CAF destruction reshaped the tumor stroma to favor T-cell infiltration and tumor inhibition. CONCLUSIONS: This study unveiled a novel therapy-attIL12-T cells-for targeting CAFs/ECM. These findings are highly relevant to humans because CAFs are abundant in human osteosarcoma.

Comparative analysis of immune infiltrates in head and neck cancers across anatomical sites.

BACKGROUND: The response rate to immune checkpoint inhibitors targeting programmed cell death 1 (PD-1) receptor is 13%-18% for patients with recurrent or metastatic head and neck squamous cell carcinoma (HNSCC). Detailed understanding of the tumor immune microenvironment (TIME) is crucial in order to explain and improve this response rate. HNSCCs arise at various anatomical locations including the oral cavity, hypopharynx, larynx and oropharynx. Studies directly comparing immune infiltration between anatomical sites are scarce. Since the distinct locations could drive deviating microenvironments, we questioned whether the immune composition varies across these HNSCC sites. METHODS: Here, we characterized the TIME of 76 fresh tumor specimens using flow cytometry and performed single-cell RNA-sequencing on nine head and neck tumor samples. RESULTS: We found major differences in the composition of the TIME between patients. When comparing anatomical sites: tumors originating from the oral cavity had higher T cell infiltrates than tumors from other anatomical sites. The percentage of tumor-infiltrating T-lymphocytes positive for the immune checkpoint PD-1 varied considerably between patients, with the highest fraction of PD-1+ T cells found in larynx squamous cell carcinomas (SCCs). While we had hypothesized that the anatomical sites of tumor origin would drive sample clustering, our data showed that the type of TIME was more dominant and was particularly driven by the fraction of T cells positive for PD-1. Moreover, a high proportion of PD-1+ CD8+ T cells associated with an improved overall survival. Using single-cell RNA-sequencing, we observed that PD-1 expression was highest in the CD8-ENTPD1 tissue resident memory T cell/exhausted T cell and CD4-CXCL13 type 1 T helper cell clusters. CONCLUSIONS: We found that oral cavity SCCs had the highest frequencies of T cells. We also observed considerable interpatient heterogeneity for PD-1 on T cells, with noticeably higher frequencies of PD-1+ CD4+ T helper cells in larynx SCCs. Within the entire cohort, a higher fraction of CD8+ T cells positive for PD-1 was linked to improved overall survival. Whether the fraction of PD-1+ T cells within the TIME enables immune checkpoint inhibitor response prediction for patients with head and neck cancer remains to be determined.

RCAd-LTH-shPD-L1, a double-gene recombinant oncolytic adenovirus with enhanced antitumor immunity, increases lymphocyte infiltration and reshapes the tumor microenvironment.

BACKGROUND: With the successful development of modern immunotherapy, immune checkpoint inhibitors (ICIs) are currently considered potential therapeutic options for patients with cancer. However, the therapeutic potential of ICIs in human cancer is mainly limited by their systemic toxicity and low response rate, which suggests the necessity of local drug delivery with an effective vector and reshaping the immunosuppressive tumor microenvironment (TME) to enhance ICI therapy. Here, we constructed a novel double-gene recombinant oncolytic adenovirus named RCAd-LTH-shPD-L1 based on the RCAd virus platform armed with a DNA fragment encoding an anti-VEGF antibody and shRNA to inhibit PD-L1 expression. METHODS: The correct assembly of RCAd-LTH-shPD-L1 was characterized by analyzing its secretion, antigen specificity, and replication using western blotting, ELISA and quantitative PCR, respectively. The in vitro effects of RCAd-LTH-shPD-L1 on cell proliferation, vasculogenic, and cell migration were assessed. Antitumor effects and therapeutic mechanisms were evaluated in vivo using immunodeficient and humanized immune system mouse models. The TME was studied by ELISA, immunohistochemistry and flow cytometry. RESULTS: RCAd-LTH-shPD-L1 cells secreted anti-VEGF antibodies and inhibited the expression of PD-L1 in cancer cells. Moreover, RCAd-LTH-shPD-L1 exerted a specific cytotoxic effect on human cancer cells, but not on murine cancer cells or normal human cells. RCAd-LTH-shPD-L1 elicited a more potent antitumor effect in an immunodeficient mouse model and a humanized immune system mouse model than RCAd-shPD-L1, as demonstrated by the significant decrease in tumor growth. Furthermore, RCAd-LTH-shPD-L1 modulated the TME, which led to lymphocyte infiltration and alteration of their immune phenotype, as characterized by downregulation of anoxic factor HIF-1α and angiogenesis marker CD31, upregulation of cytokine such as IFN-γ, IL-6 and IL-12. CONCLUSIONS: In summary, our data demonstrated that the localized delivery of anti-VEGF antibodies and shPD-L1 by engineered RCAd-LTH-shPD-L1 is a highly effective and safe strategy for cancer immunotherapy. Moreover, the data underscore the potential of combining local virotherapy and anti-angiogenic therapy with ICIs as an effective TME therapy for poorly infiltrating tumors.

Biomarkers of pembrolizumab efficacy in advanced anal squamous cell carcinoma: analysis of a phase II clinical trial and a cohort of long-term responders.

BACKGROUND: Recent trials suggest that programmed cell death 1 (PD-1)-directed immunotherapy may be beneficial for some patients with anal squamous cell carcinoma and biomarkers predictive of response are greatly needed. METHODS: This multicenter phase II clinical trial (NCT02919969) enrolled patients with metastatic or locally advanced incurable anal squamous cell carcinoma (n=32). Patients received pembrolizumab 200 mg every 3 weeks. The primary endpoint of the trial was objective response rate (ORR). Exploratory objectives included analysis of potential predictive biomarkers including assessment of tumor-associated immune cell populations with multichannel immunofluorescence and analysis of circulating tumor tissue modified viral-human papillomavirus DNA (TTMV-HPV DNA) using serially collected blood samples. To characterize the clinical features of long-term responders, we combined data from our prospective trial with a retrospective cohort of patients with anal cancer treated with anti-PD-1 immunotherapy (n=18). RESULTS: In the phase II study, the ORR to pembrolizumab monotherapy was 9.4% and the median progression-free survival was 2.2 months. Despite the high level of HPV positivity observed with circulating TTMV-HPV DNA testing, the majority of patients had low levels of tumor-associated CD8+PD-1+ T cells on pretreatment biopsy. Patients who benefited from pembrolizumab had decreasing TTMV-HPV DNA scores and a complete responder's TTMV-HPV DNA became undetectable. Long-term pembrolizumab responses were observed in one patient from the trial (5.3 years) and three patients (2.5, 6, and 8 years) from the retrospective cohort. Long-term responders had HPV-positive tumors, lacked liver metastases, and achieved a radiological complete response. CONCLUSIONS: Pembrolizumab has durable efficacy in a rare subset of anal cancers. However, despite persistence of HPV infection, indicated by circulating HPV DNA, most advanced anal cancers have low numbers of tumor-associated CD8+PD-1+ T cells and are resistant to pembrolizumab.

LRP11 promotes stem-like T cells via MAPK13-mediated TCF1 phosphorylation, enhancing anti-PD1 immunotherapy.

BACKGROUND: Tumor-infiltrating T cells enter an exhausted or dysfunctional state, which limits antitumor immunity. Among exhausted T cells, a subset of cells with features of progenitor or stem-like cells has been identified as TCF1+ CD8+ T cells that respond to immunotherapy. In contrast to the finding that TCF1 controls epigenetic and transcriptional reprogramming in tumor-infiltrating stem-like T cells, little is known about the regulation of TCF1. Emerging data show that elevated body mass index is associated with outcomes of immunotherapy. However, the mechanism has not been clarified. METHODS: We investigated the proliferation of splenic lymphocytes or CD8+ T cells induced by CD3/CD28 stimulation in vitro. We evaluated the effects of low-density lipoprotein (LDL) and LRP11 inhibitors, as well as MAPK13 inhibitors. Additionally, we used shRNA technology to validate the roles of LRP11 and MAPK13. In an in vivo setting, we employed male C57BL/6J injected with B16 cells or MC38 cells to build a tumor model to assess the effects of LDL and LRP11 inhibitors, LRP11 activators, MAPK13 inhibitors on tumor growth. Flow cytometry was used to measure cell proportions and activation status. Molecular interactions and TCF1 status were examined using Western blotting. Moreover, we employed RNA sequencing to investigate the effects of LDL stimulation and MAPK13 inhibition in CD8+ T cells. RESULTS: By using a tumor-bearing mouse model, we found that LDL-induced tumor-infiltrating TCF1+PD1+CD8+ T cells. Using a cell-based chimeric receptor screening system, we showed that LRP11 interacted with LDL and activated TCF1. LRP11 activation enhanced TCF1+PD1+CD8+ T-cell-mediated antitumor immunity, consistent with LRP11 blocking impaired T-cell function. Mechanistically, LRP11 activation induces MAPK13 activation. Then, MAPK13 phosphorylates TCF1, leading to increase of stem-like T cells. CONCLUSIONS: LRP11-MAPK13-TCF1 enhanced antitumor immunity and induced tumor-infiltrating stem-like T cells.

CXCL10 and Nrf2-upregulated mesenchymal stem cells reinvigorate T lymphocytes for combating glioblastoma.

BACKGROUND: Lack of tumor-infiltrating T lymphocytes and concurrent T-cell dysfunction have been identified as major contributors to glioblastoma (GBM) immunotherapy resistance. Upregulating CXCL10 in the tumor microenvironment (TME) is a promising immunotherapeutic approach that potentially increases tumor-infiltrating T cells and boosts T-cell activity but is lacking effective delivery methods. METHODS: In this study, mesenchymal stem cells (MSCs) were transduced with a recombinant lentivirus encoding Cxcl10, Nrf2 (an anti-apoptosis gene), and a ferritin heavy chain (Fth) reporter gene in order to increase their CXCL10 secretion, TME survival, and MRI visibility. Using FTH-MRI guidance, these cells were injected into the tumor periphery of orthotopic GL261 and CT2A GBMs in mice. Combination therapy consisting of CXCL10-Nrf2-FTH-MSC transplantation together with immune checkpoint blockade (ICB) was also performed for CT2A GBMs. Thereafter, in vivo and serial MRI, survival analysis, and histology examinations were conducted to assess the treatments' efficacy and mechanism. RESULTS: CXCL10-Nrf2-FTH-MSCs exhibit enhanced T lymphocyte recruitment, oxidative stress tolerance, and iron accumulation. Under in vivo FTH-MRI guidance and monitoring, peritumoral transplantation of CXCL10-Nrf2-FTH-MSCs remarkably inhibited orthotopic GL261 and CT2A tumor growth in C57BL6 mice and prolonged animal survival. While ICB alone demonstrated no therapeutic impact, CXCL10-Nrf2-FTH-MSC transplantation combined with ICB demonstrated an enhanced anticancer effect for CT2A GBMs compared with transplanting it alone. Histology revealed that peritumorally injected CXCL10-Nrf2-FTH-MSCs survived longer in the TME, increased CXCL10 production, and ultimately remodeled the TME by increasing CD8+ T cells, interferon-γ+ cytotoxic T lymphocytes (CTLs), GzmB+ CTLs, and Th1 cells while reducing regulatory T cells (Tregs), exhausted CD8+ and exhausted CD4+ T cells. CONCLUSIONS: MRI-guided peritumoral administration of CXCL10 and Nrf2-overexpressed MSCs can significantly limit GBM growth by revitalizing T lymphocytes within TME. The combination application of CXCL10-Nrf2-FTH-MSC transplantation and ICB therapy presents a potentially effective approach to treating GBM.

Timed adoptive T cell transfer during chemotherapy in patients with recurrent platinum-sensitive epithelial ovarian cancer.

BACKGROUND: The presence of T cells and suppressive myeloid cells in epithelial ovarian cancer (EOC) correlate with good and bad clinical outcome, respectively. This suggests that EOC may be sensitive to adoptive cell therapy with autologous tumor-infiltrating lymphocytes (TIL), provided that immunosuppression by myeloid-derived suppressor cells and M2 macrophages is reduced. Platinum-based chemotherapy can alleviate such immunosuppression, potentially creating a window of opportunity for T cell-based immunotherapy. METHODS: We initiated a phase I/II trial (NCT04072263) in patients with recurrent platinum-sensitive EOC receiving TIL during platinum-based chemotherapy. TILs were administered 2 weeks after the second, third and fourth chemotherapy course. Patients were treated in two cohorts with or without interferon-α (IFNa), as conditioning and TIL support regimen. The primary endpoint was to evaluate the feasibility and safety according to CTCAE V.4.03 criteria and the clinical response and immune modulatory effects of this treatment were evaluated as secondary endpoints. RESULTS: Sixteen patients were enrolled. TIL could be successfully expanded for all patients. TIL treatment during chemotherapy without IFNa (n=13) was safe but the combination with IFNa added to the chemotherapy-induced toxicity with 2 out of 3 patients developing thrombocytopenia as dose-limiting toxicity. Fourteen patients completed treatment with a full TIL cycle and were further evaluated for clinical and immunological response. Platinum-based chemotherapy resulted in reduction of circulating myeloid cell numbers and IL-6 plasma levels, confirming its immunosuppression-alleviating effect. Three complete (CR), nine partial responses and two stable diseases were recorded, resulting in an objective response rate of 86% (Response Evaluation Criteria In Solid Tumors V.1.1). Interestingly, progression free survival that exceeded the previous platinum-free interval was detected in two patients, including an exceptionally long and ongoing CR in one patient that coincided with sustained alleviation of immune suppression. CONCLUSION: TIL therapy can be safely combined with platinum-based chemotherapy but not in combination with IFNa. The chemotherapy-mediated reduction in immunosuppression and the increase in platinum-free interval for two patients warrants further exploration of properly-timed TIL infusions during platinum-based chemotherapy, possibly further benefiting from IL-2 support, as a novel treatment option for EOC patients.

MDR1-EXPRESSING CD4+ T CELLS WITH TH1.17 FEATURES RESIST TO NEOADJUVANT CHEMOTHERAPY AND ARE ASSOCIATED WITH BREAST CANCER CLINICAL RESPONSE.

BACKGROUND: Multidrug resistance-1 (MDR1) transporter limits the intracellular accumulation of chemotherapies (paclitaxel, anthracyclines) used in breast cancer (BC) treatment. In addition to tumor cells, MDR1 is expressed on immune cell subsets in which it confers chemoresistance. Among human T cells, MDR1 is expressed by most CD8+ T cells, and a subset of CD4+ T helper (Th) cells. Here we explored the expression, function and regulation of MDR1 on CD4+ T cells and investigated the role of this population in response to neoadjuvant chemotherapy (NAC) in BC. METHODS: Phenotypic and functional characteristics of MDR1+ CD4 Th cells were assessed on blood from healthy donors and patients with BC by flow cytometry. These features were extended to CD4+ Th cells from untreated breast tumor by flow cytometry and RNA-sequencing (RNA-seq). We performed in vitro polarization assays to decipher MDR1 regulation on CD4 Th cells. We evaluated in vitro the impact of chemotherapy agents on MDR1+ CD4+ Th cells. We analyzed the impact of NAC treatment on MDR1+ CD4+ Th cells from blood and tumors and their association with treatment efficacy in two independent BC cohorts and in a public RNA-seq data set of BC tumor biopsies before and after NAC. Finally, we performed single cell (sc) RNAseq of blood CD4+ memory T cells from NAC-treated patients and combined them with an scRNAseq public data set. RESULTS: MDR1+ CD4 Th cells were strongly enriched in Th1.17 polyfunctional cells but also in Th17 cells, both in blood and untreated breast tumor tissues. Mechanistically, Tumor growth factor (TGF)-ß1 was required for MDR1 induction during in vitro Th17 or Th1.17 polarization. MDR1 expression conferred a selective advantage to Th1.17 and Th17 cells following paclitaxel treatment in vitro and in vivo in NAC-treated patients. scRNAseq demonstrated MDR1 association with tumor Th1.17 and Th with features of cytotoxic cells. Enrichment in MDR1+ CD4+ Th1.17 and Th17 cells, in blood and tumors positively correlated with pathological response. Absence of early modulation of Th1.17 and Th17 in NAC-resistant patients, argue for its use as a biomarker for chemotherapy regimen adjustment. CONCLUSION: MDR1 favored the enrichment of Th1.17 and Th17 in blood and tumor after NAC that correlated to clinical response.

Unraveling the impact of sialic acids on the immune landscape and immunotherapy efficacy in pancreatic cancer.

BACKGROUND: Pancreatic ductal adenocarcinoma (PDAC) is one of the deadliest cancers. Despite the successful application of immune checkpoint blockade in a range of human cancers, immunotherapy in PDAC remains unsuccessful. PDAC is characterized by a desmoplastic, hypoxic and highly immunosuppressive tumor microenvironment (TME), where T-cell infiltration is often lacking (immune desert), or where T cells are located distant from the tumor islands (immune excluded). Converting the TME to an immune-inflamed state, allowing T-cell infiltration, could increase the success of immunotherapy in PDAC. METHOD: In this study, we use the KPC3 subcutaneous PDAC mouse model to investigate the role of tumor-derived sialic acids in shaping the tumor immune landscape. A sialic acid deficient KPC3 line was generated by genetic knock-out of the CMAS (cytidine monophosphate N-acetylneuraminic acid synthetase) enzyme, a critical enzyme in the synthesis of sialic acid-containing glycans. The effect of sialic acid-deficiency on immunotherapy efficacy was assessed by treatment with anti-programmed cell death protein 1 (PD-1) and agonistic CD40. RESULT: The absence of sialic acids in KPC3 tumors resulted in increased numbers of CD4+ and CD8+ T cells in the TME, and reduced frequencies of CD4+ regulatory T cells (Tregs) within the T-cell population. Importantly, CD8+ T cells were able to infiltrate the tumor islands in sialic acid-deficient tumors. These favorable alterations in the immune landscape sensitized sialic acid-deficient tumors to immunotherapy, which was ineffective in sialic acid-expressing KPC3 tumors. In addition, high expression of sialylation-related genes in human pancreatic cancer correlated with decreased CD8+ T-cell infiltration, increased presence of Tregs, and poorer survival probability. CONCLUSION: Our results demonstrate that tumor-derived sialic acids mediate T-cell exclusion within the PDAC TME, thereby impairing immunotherapy efficacy. Targeting sialic acids represents a potential strategy to enhance T-cell infiltration and improve immunotherapy outcomes in PDAC.

MCT4 blockade increases the efficacy of immune checkpoint blockade.

BACKGROUND & AIMS: Intratumoral lactate accumulation and acidosis impair T-cell function and antitumor immunity. Interestingly, expression of the lactate transporter monocarboxylate transporter (MCT) 4, but not MCT1, turned out to be prognostic for the survival of patients with rectal cancer, indicating that single MCT4 blockade might be a promising strategy to overcome glycolysis-related therapy resistance. METHODS: To determine whether blockade of MCT4 alone is sufficient to improve the efficacy of immune checkpoint blockade (ICB) therapy, we examined the effects of the selective MCT1 inhibitor AZD3965 and a novel MCT4 inhibitor in a colorectal carcinoma (CRC) tumor spheroid model co-cultured with blood leukocytes in vitro and the MC38 murine CRC model in vivo in combination with an antibody against programmed cell death ligand-1(PD-L1). RESULTS: Inhibition of MCT4 was sufficient to reduce lactate efflux in three-dimensional (3D) CRC spheroids but not in two-dimensional cell-cultures. Co-administration of the MCT4 inhibitor and ICB augmented immune cell infiltration, T-cell function and decreased CRC spheroid viability in a 3D co-culture model of human CRC spheroids with blood leukocytes. Accordingly, combination of MCT4 and ICB increased intratumoral pH, improved leukocyte infiltration and T-cell activation, delayed tumor growth, and prolonged survival in vivo. MCT1 inhibition exerted no further beneficial impact. CONCLUSIONS: These findings demonstrate that single MCT4 inhibition represents a novel therapeutic approach to reverse lactic-acid driven immunosuppression and might be suitable to improve ICB efficacy.

Discovery of a glucocorticoid receptor (GR) activity signature correlates with immune cell infiltration in adrenocortical carcinoma.

BACKGROUND: Adrenocortical carcinoma (ACC) is a rare and highly aggressive endocrine malignancy, of which >40% present with glucocorticoid excess. Glucocorticoids and glucocorticoid receptor (GR) signaling have long been thought to suppress immunity and promote tumor progression by acting on immune cells. Here, we provide new insights into the interaction between GR signaling activity and the immune signature of ACC as a potential explanation for immune escape and resistance to immunotherapy. METHODS: First, GR immunohistochemical staining and immunofluorescence analysis of tumor-infiltrating lymphocyte (CD4 T, CD8 T cells, natural killer (NK) cells, dendritic cells and macrophages) were performed in 78 primary ACC tissue specimens. Quantitative data of immune cell infiltration in ACC were correlated with clinical characteristics. Second, we discovered a GR activity signature (GRsig) using GR-targeted gene networks derived from global gene expression data of primary ACC. Finally, we identified two GRsig-related subtypes based on the GRsig and assessed the differences in immune characteristics and prognostic stratification between the two subtypes. RESULTS: GR was expressed in 90% of the ACC tumors, and CD8+ cytotoxic T lymphocytes were the most common infiltrating cell type in ACC specimens (88%, 8.6 cells/high power field). GR expression positively correlated with CD8+ T cell (Phi=0.342, p<0.001), CD4+ T cell (Phi=0.280, p<0.001), NK cell (Phi=0.280, p<0.001), macrophage (Phi=0.285, p<0.001), and dendritic cell (Phi=0.397, p<0.001) infiltration. Clustering heatmap analysis also displayed high immune cell infiltration in GR high-expressing tumors and low immune cell infiltration in GR-low tumors. High GR expression and high immune cell infiltration were significantly associated with better survival. Glucocorticoid excess is associated with low immune cell abundance and unfavorable prognosis. A GRsig comprizing n=34 GR-associated genes was derived from Gene Expression Omnibus/The Cancer Genome Atlas (TCGA) data sets and used to define two GRsig-related subtypes in the TCGA cohort. We demonstrated distinct differences in the immune landscape and clinical outcomes between the two subtypes. CONCLUSION: GR expression positively correlates with tumor-infiltrating immune cells in ACC. The GRsig could serve as a prognostic biomarker and may be helpful for prognosis prediction and response to immunotherapy. Consequently, targeting the GR signaling pathway might be pivotal and should be investigated in clinical studies.

Neoantigen-specific CD4+ tumor-infiltrating lymphocytes are potent effectors identified within adoptive cell therapy products for metastatic melanoma patients.

BACKGROUND: Adoptive cell therapy (ACT) with tumor-infiltrating lymphocytes (TILs) is a promising immunotherapeutic approach for patients with advanced solid tumors. While numerous advances have been made, the contribution of neoantigen-specific CD4+T cells within TIL infusion products remains underexplored and therefore offers a significant opportunity for progress. METHODS: We analyzed infused TIL products from metastatic melanoma patients previously treated with ACT for the presence of neoantigen-specific T cells. TILs were enriched on reactivity to neoantigen peptides derived and prioritized from patient sample-directed mutanome analysis. Enriched TILs were further investigated to establish the clonal neoantigen response with respect to function, transcriptomics, and persistence following ACT. RESULTS: We discovered that neoantigen-specific TIL clones were predominantly CD4+ T cells and were present in both therapeutic responders and non-responders. CD4+ TIL demonstrated an effector T cell response with cytotoxicity toward autologous tumor in a major histocompatibility complex class II-dependent manner. These results were validated by paired TCR and single cell RNA sequencing, which elucidated transcriptomic profiles distinct to neoantigen-specific CD4+ TIL. CONCLUSIONS: Despite methods which often focus on CD8+T cells, our study supports the importance of prospective identification of neoantigen-specific CD4+ T cells within TIL products as they are a potent source of tumor-specific effectors. We further advocate for the inclusion of neoantigen-specific CD4+ TIL in future ACT protocols as a strategy to improve antitumor immunity.

KLRG1 marks tumor-infiltrating CD4 T cell subsets associated with tumor progression and immunotherapy response.

Current methods for biomarker discovery and target identification in immuno-oncology rely on static snapshots of tumor immunity. To thoroughly characterize the temporal nature of antitumor immune responses, we developed a 34-parameter spectral flow cytometry panel and performed high-throughput analyses in critical contexts. We leveraged two distinct preclinical models that recapitulate cancer immunoediting (NPK-C1) and immune checkpoint blockade (ICB) response (MC38), respectively, and profiled multiple relevant tissues at and around key inflection points of immune surveillance and escape and/or ICB response. Machine learning-driven data analysis revealed a pattern of KLRG1 expression that uniquely identified intratumoral effector CD4 T cell populations that constitutively associate with tumor burden across tumor models, and are lost in tumors undergoing regression in response to ICB. Similarly, a Helios-KLRG1+ subset of tumor-infiltrating regulatory T cells was associated with tumor progression from immune equilibrium to escape and was also lost in tumors responding to ICB. Validation studies confirmed KLRG1 signatures in human tumor-infiltrating CD4 T cells associate with disease progression in renal cancer. These findings nominate KLRG1+ CD4 T cell populations as subsets for further investigation in cancer immunity and demonstrate the utility of longitudinal spectral flow profiling as an engine of dynamic biomarker discovery.

Inhibition of tumor intrinsic BANF1 activates antitumor immune responses via cGAS-STING and enhances the efficacy of PD-1 blockade.

BACKGROUND: BANF1 is well known as a natural opponent of cyclic GMP-AMP synthase (cGAS) activity on genomic self-DNA. However, the roles of BANF1 in tumor immunity remain unclear. Here, we investigate the possible impact of BANF1 on antitumor immunity and response to immunotherapy. METHODS: The Cancer Genome Atlas public data were analyzed to evaluate the relevance of the expression of BANF1, patients' survival and immune cell infiltration. We monitored tumor growth and explored the antitumor efficacy of targeting tumor-intrinsic BANF1 in combination with anti-programmed cell death protein-1 (PD-1) in MC38 or B16F10 tumor models in both immunocompetent and immunodeficient mice. Flow cytometry, immunofluorescence and T cells depletion experiments were used to validate the role of BANF1 in tumor immune microenvironment reprogramming. RNA sequencing was then used to interrogate the mechanisms how BANF1 regulated antitumor immunity. RESULTS: We show that upregulated expression of BANF1 in tumor tissues is significantly associated with poor survival and is negatively correlated with immune cell infiltration. Deficiency of BANF1 in tumor cells markedly antagonizes tumor growth in immunocompetent but not immunocompromised mice, and enhances the response to immunotherapy in murine models of melanoma and colon cancer. In the immunotherapy clinical cohort, patients with high BANF1 expression had a worse prognosis. Mechanistically, BANF1 knockout activates antitumor immune responses mediated by cGAS-synthase-stimulator of interferon genes (cGAS-STING) pathway, resulting in an immune-activating tumor microenvironment including increased CD8+ T cell infiltration and decreased myeloid-derived suppressor cell enrichment. CONCLUSIONS: BANF1 is a key regulator of antitumor immunity mediated by cGAS-STING pathway. Therefore, our study provides a rational that targeting BANF1 is a potent strategy for enhancing immunotherapy for cancer with BANF1 upregulation.

C1q+ tumor-associated macrophages contribute to immunosuppression through fatty acid metabolic reprogramming in malignant pleural effusion.

BACKGROUND: Although immune checkpoint blockade (ICB) therapy has shown remarkable benefits in cancers, a subset of patients with cancer exhibits unresponsiveness or develop acquired resistance due to the existence of abundant immunosuppressive cells. Tumor-associated macrophages (TAMs), as the dominant immunosuppressive population, impede the antitumor immune response; however, the underlying mechanisms have not been fully elucidated yet. METHODS: Single-cell RNA sequencing analysis was performed to portray macrophage landscape and revealed the underlying mechanism of component 1q (C1q)+ TAMs. Malignant pleural effusion (MPE) of human and mouse was used to explore the phenotypes and functions of C1q+ TAMs. RESULTS: C1q+ TAMs highly expressed multiple inhibitory molecules and their high infiltration was significantly correlated with poor prognosis. C1q+ TAMs promote MPE immunosuppression through impairing the antitumor effects of CD8+ T cells. Mechanistically, C1q+ TAMs enhance fatty acid binding protein 5 (FABP5)-mediated fatty acid metabolism, which activate transcription factor peroxisome proliferator-activated receptor-gamma, increasing the gene expression of inhibitory molecules. A high-fat diet increases the expression of inhibitory molecules in C1q+ TAMs and the immunosuppression of MPE microenvironment, whereas a low-fat diet ameliorates these effects. Moreover, FABP5 inhibition represses the expression of inhibitory molecules in TAMs and tumor progression, while enhancing the efficacy of ICB therapy in MPE and lung cancer. CONCLUSIONS: C1q+ TAMs impede antitumor effects of CD8+ T cells promoting MPE immunosuppression. Targeting C1q+ TAMs effectively alleviates the immunosuppression and enhances the efficacy of ICB therapy. C1q+ TAMs subset has great potential to be a therapeutic target for cancer immunotherapy.