CD4+ T cell exhaustion leads to adoptive transfer therapy failure which can be prevented by immune checkpoint blockade

Cytotoxic CD8⁺ T cell exhaustion is one of the mechanisms underlying the tumor immune escape. The paradigm-shifting immune checkpoint therapy can mitigate CD8⁺ T lymphocyte exhaustion, reinvigorate the anticancer immunity, and achieve durable tumor regression for some patients. Emerging evidence indicates that CD4⁺ T lymphocytes also have a critical role in anticancer immunity, either by directly applying cytotoxicity toward cancer cells or as a helper to augment CD8⁺ T cell cytotoxicity. Whether anticancer CD4⁺ T lymphocytes undergo exhaustion during immunotherapy of solid tumors remains unknown. Here we report that melanoma antigen TRP-1/gp75-specific CD4⁺ T lymphocytes exhibit an exhaustion phenotype after being adoptively transferred into mice bearing large subcutaneous melanoma. Exhaustion of these CD4⁺ T lymphocytes is accompanied with reduced cytokine release and increased expression of inhibitory receptors, resulting in loss of tumor control. Importantly, we demonstrate that PD-L1 immune checkpoint blockade can prevent exhaustion, induce proliferation of the CD4⁺ T lymphocytes, and consequently prevent tumor recurrence. Therefore, when encountering an excessive amount of tumor antigens, tumor-reactive CD4⁺ T lymphocytes also enter the exhaustion state, which can be prevented by immune checkpoint blockade. Our results highlight the importance of tumor-specific CD4⁺ T lymphocytes in antitumor immunity and suggest that the current immune checkpoint blockade therapy may achieve durable anticancer efficacy by rejuvenating both tumor antigen-specific CD8⁺ T lymphocytes and CD4⁺ T lymphocytes.     

Complement receptor C5aR1 blockade reprograms tumor-associated macrophages and synergizes with anti-PD-1 therapy in gastric cancer

In gastric cancer (GC), the therapeutic response of immune checkpoint blockade (ICB) remains suboptimal. Targeting myeloid cell checkpoints might be feasible as adjuvant to current ICB regimens. We sought to evaluate the crucial role of C5aR1⁺ TAMs in regulating antitumor immunity and the efficacy of combinatorial treatment with antiprogrammed cell death protein-1 (PD-1) and C5aR1 blockade. Here, we found that C5aR1 was predominantly expressed on macrophages and high level of C5aR1⁺ TAMs infiltration could predict poor prognosis and inferior chemotherapeutic response. The flow cytometry (FCM) and single-cell RNA-seq (scRNA-seq) data revealed that C5aR1⁺ TAMs exhibited immunosuppressive property which might contribute to CD8⁺ T cell dysfunction. Blockade of C5aR1 could diminish the immunosuppressive function of TAMs and led to reinvigorated CD8⁺ T cells mediated antitumor immunity. Moreover, using in vitro intervention experiment based on fresh GC surgical specimens, we discovered that C5aR1 blockade exert a synergistic effect when combined with PD-1 inhibitor for tumor clearance. Our study demonstrated that C5aR1 is a critical myeloid checkpoint and plays a crucial role in regulating the immunosuppressive property of TAMs and CD8⁺ T cell immune tolerance. C5aR1 blockade reprograms TAMs and reinvigorated the cytotoxicity of CD8⁺ T cells, thus improving the efficacy of anti-PD-1 therapy for tumor eradication in GC.     

Relationship between the expressions of PD-L1 and tumor-infiltrating lymphocytes in oral squamous cell carcinoma

Tumor-infiltrating lymphocytes (TILs) are considered to represent immune reactions of the host to a malignant tumor. Programmed death receptor ligand-1 (PD-L1) is a surface protein that blocks the function of T lymphocytes and is expressed on cancer cells. Tumor-associated fibroblasts (TAFs), which influence tumor growth have also been reported to express PD-L1 and thus inhibit TILs. In the present study, we investigated the densities of CD4⁺/CD8⁺ TILs, PD-L1 expression of tumor cells and TAFs in oral squamous cell carcinoma (OSCC). Forty-five cases of OSCC were selected. We evaluated PD-L1 expression and the infiltration degree of each lymphocyte by immunohistochemical examination. These data were analyzed in connection with clinicopathological factors. Peritumoral CD8⁺ TILs were observed in every patient with OSCC, and their densities were correlated with lymph node metastasis (P < 0.001), tumor size (P = 0.003), and clinical stage (P < 0.001). PD-L1 expression on OSCC cells was observed in 39 cases and was associated with the lower density of intratumoral CD8⁺ TILs (P = 0.047). PD-L1 expression of tumors <4 cm in size was correlated with the histological grade of the tumor (P = 0.022). TAFs were positive for PD-L1 in 18 cases. Peritumoral TILs were significantly associated with tumor size, lymph node metastasis and clinical stage. Though PD-L1 expressed by OSCC cells did not affect patients’ survival, its correlation with decreased number of intratumoral TILs suggests that the development of a strategy to block the interactions of PD-L1 with TIL would be a useful tool for inhibiting tumor growth.     

Immunotherapies targeting neoantigens are effective in PD-1 blockade-resistant tumors

Only a small fraction of tumor-infiltrating lymphocytes can specifically recognize and attack cancer cells in PD-1/PD-L1 blockade therapy. Here, we investigate approaches to expand the neoantigen-specific CD8⁺ T cells to overcome the difficulties in treating PD-1/PD-L1 blockade-resistant tumors. Mutation-associated neoepitopes of murine nonsmall cell lung cancer ASB-XIV were estimated by whole-exome and RNA sequencing and predicted by MHC-I binding affinity (FPKM >1) in silico. Using ASB-XIV-specific CD8⁺ T cells, we screened a panel of 257 neoepitope peptides derived from ASB-XIV missense and indel mutations. Mutated Phf3 peptide (mPhf3) was successfully identified as an immunogenic neoepitope. Prophylactic mPhf3-DC vaccination inhibited ASB-XIV tumor growth through CD8⁺ T cell-mediated antitumor immunity. Combining the mPhf3-DC vaccine and anti-PD-1 treatment elicited robust antitumor activity through the induction of mPhf3-specific CD8⁺ T cells in the tumor microenvironment. Furthermore, the adoptive transfer of mPhf3-specific CD8⁺ T cells eradicated ASB-XIV tumors. Likewise, the combination of mutated Cdt1 peptide (mCdt1)-DC vaccine and anti-PD-1 treatment or adoptive transfer of mCdt1-specific CD8⁺ T cells also led to significant regression of PD-1 blockade-resistant murine gastric YTN16 tumors. In conclusion, a novel immunogenic neoepitope of ASB-XIV was identified for immunotherapy targeting neoantigens. Identification of immunogenic neoantigens can extend the therapeutic strategies by increasing the frequency of neoantigen-specific T cells, even for PD-1/PD-L1 blockade-resistant tumors.     

Hyperprogressive disease during PD-1/PD-L1 blockade in patients with non-small-cell lung cancer

BackgroundImmune checkpoint blockade with Programmed cell death 1 (PD-1)/PD-L1 inhibitors has been effective in various malignancies and is considered as a standard treatment modality for patients with non-small-cell lung cancer (NSCLC). However, emerging evidence show that PD-1/PD-L1 blockade can lead to hyperprogressive disease (HPD), a flair-up of tumor growth linked to dismal prognosis. This study aimed to evaluate the incidence of HPD and identify the determinants associated with HPD in patients with NSCLC treated with PD-1/PD-L1 blockade.Patients and methodsWe enrolled patients with recurrent and/or metastatic NSCLC treated with PD-1/PD-L1 inhibitors between April 2014 and November 2018. Clinicopathologic variables, dynamics of tumor growth, and treatment outcomes were analyzed in patients with NSCLC who received PD-1/PD-L1 blockade. HPD was defined according to tumor growth kinetics (TGK), tumor growth rate (TGR), and time to treatment failure (TTF). Immunophenotyping of peripheral blood CD8⁺ T lymphocytes was conducted to explore the potential predictive biomarkers of HPD.ResultsA total of 263 patients were analyzed. HPD was observed in 55 (20.9%), 54 (20.5%), and 98 (37.3%) patients according to the TGK, TGR, and TTF. HPD meeting both TGK and TGR criteria was associated with worse progression-free survival [hazard ratio (HR) 4.619; 95% confidence interval (CI) 2.868–7.440] and overall survival (HR, 5.079; 95% CI, 3.136–8.226) than progressive disease without HPD. There were no clinicopathologic variables specific for HPD. In the exploratory biomarker analysis with peripheral blood CD8⁺ T lymphocytes, a lower frequency of effector/memory subsets (CCR7⁻CD45RA⁻ T cells among the total CD8⁺ T cells) and a higher frequency of severely exhausted populations (TIGIT⁺ T cells among PD-1⁺CD8⁺ T cells) were associated with HPD and inferior survival rate.ConclusionHPD is common in NSCLC patients treated with PD-1/PD-L1 inhibitors. Biomarkers derived from rationally designed analysis may successfully predict HPD and worse outcomes, meriting further investigation of HPD.     

Intratumoral CD39+CD8+ T Cells Predict Response to Programmed Cell Death Protein-1 or Programmed Death Ligand-1 Blockade in Patients With NSCLC

IntroductionProgrammed cell death protein-1 (PD-1) and programmed death-ligand 1 (PD-L1) blockade is currently widely used in the treatment of metastatic NSCLC. Despite available biomarker stratification, clinical responses vary. Thus, the search for novel biomarkers with improved response prediction is ongoing. Previously, using mass cytometry or cytometry by time-of-flight (CyTOF), our group demonstrated that CD39⁺CD8⁺ immune cells represent tumor antigen-specific, cytotoxic T cells in treatment-naive NSCLC. We hypothesized that accurate quantitation of this T cell subset would predict immunotherapy outcome.MethodsTo translate this to a clinical setting, the present study compared CyTOF data with a range of clinically relevant methods, including conventional immunohistochemistry (IHC), multiplex IHC or immunofluorescence (mIHC), and gene expression assay by NanoString.ResultsQuantification using mIHC but not conventional IHC or NanoString correlated with the CyTOF results. The specificity and sensitivity of mIHC were then evaluated in a separate retrospective NSCLC cohort. CD39⁺CD8⁺ T cell proportion, as determined by mIHC, successfully stratified responders and nonresponders to PD-1 or PD-L1 inhibitors (objective response rate of 63.6%, compared with 0% for the negative group). This predictive capability was independent from other confounding factors, such as total CD8⁺ T cell proportion, CD39⁺ lymphocyte proportion, PD-L1 positivity, EGFR mutation status, and other clinicopathologic parameters.ConclusionsOur results suggest that the mIHC platform is a clinically relevant method to evaluate CD39⁺CD8⁺ T cell proportion and that this marker can serve as a potential biomarker that predicts response to PD-1 or PD-L1 blockade in patients with NSCLC. Further validation in additional NSCLC cohorts is warranted.     

Induction of myeloid‐derived suppressor cells by tumor exosomes

Myeloid‐derived suppressor cells (MDSCs) promote tumor progression. The mechanisms of MDSC development during tumor growth remain unknown. Tumor exosomes (T‐exosomes) have been implicated to play a role in immune regulation, however the role of exosomes in the induction of MDSCs is unclear. Our previous work demonstrated that exosomes isolated from tumor cells are taken up by bone marrow myeloid cells. Here, we extend those findings showing that exosomes isolated from T‐exosomes switch the differentiation pathway of these myeloid cells to the MDSC pathway (CD11b⁺Gr‐1⁺). The resulting cells exhibit MDSC phenotypic and functional characteristics including promotion of tumor growth. Furthermore, we demonstrated that in vivo MDSC mediated promotion of tumor progression is dependent on T‐exosome prostaglandin E2 (PGE2) and TGF‐β molecules. T‐exosomes can induce the accumulation of MDSCs expressing Cox2, IL‐6, VEGF, and arginase‐1. Antibodies against exosomal PGE2 and TGF‐β block the activity of these exosomes on MDSC induction and therefore attenuate MDSC‐mediated tumor‐promoting ability. Exosomal PGE2 and TGF‐β are enriched in T‐exosomes when compared with exosomes isolated from the supernatants of cultured tumor cells (C‐exosomes). The tumor microenvironment has an effect on the potency of T‐exosome mediated induction of MDSCs by regulating the sorting and the amount of exosomal PGE2 and TGF‐β available. Together, these findings lend themselves to developing specific targetable therapeutic strategies to reduce or eliminate MDSC‐induced immunosuppression and hence enhance host antitumor immunotherapy efficacy. © 2008 Wiley‐Liss, Inc.     

Nodal metastasis in cervical cancer occurs in clearly delineated fields of immune suppression in the pelvic lymph catchment area

In cervical cancer, high frequencies of regulatory T cells (Tregs) and immunosuppressive PD-L1⁺CD14⁺ antigen-presenting cells dominate the microenvironment of tumor-positive lymph nodes (LN+). It is unknown whether this is restricted to LN+ or precedes metastasis, emanating from the primary tumor and spreading through tumor-draining lymph nodes (TDLNs). To investigate immunosuppression in the lymphatic basin of cervical tumors, all dissected TDLNs of five cervical cancer patients (in total 9 LN+ and 74 tumor-negative lymph nodes (LN−)) were analyzed for FoxP3⁺ Tregs, CD8⁺ T cells, HLA-DR⁺- and PD-L1⁺ myeloid cells by immunohistochemistry.Tregs and PD-L1⁺ cells were found to form an immunosuppressive cordon around metastatic tumor cells. Importantly, whereas high HLA-DR⁺- and PD-L1⁺ cell rates were strongly associated with LN+, elevated Treg levels and decreased CD8⁺ T cell/Treg ratios were found similar in LN+ and adjacent LN−, as compared to LN− at more distant anatomical localizations. These data suggest that delineated fields of Treg-associated immune suppression in anatomically co-localized TDLNs enable metastasis by creating metastatic niches. This may be of importance for decision-making regarding (surgical) intervention in cervical cancer. Future efforts should include the implementation of immunotherapeutic regimens to overcome this immune suppression, establish loco-regional control and halt systemic tumor spread.     

The proportion of circulating CD45RO+CD8+ memory T cells is correlated with clinical response in melanoma patients treated with ipilimumab

BackgroundImmune checkpoint blockade (ICB) has been a breakthrough in the treatment of metastatic melanoma. But with only about 20–40% long-term responders and severe side-effects in about 12–17%, finding predictive markers for treatment response is of great interest.MethodsWe prospectively assessed clinical data, haematologic parameters and freshly isolated peripheral blood mononuclear cells of 30 patients treated with ipilimumab (n = 21) and pembrolizumab (n = 9) prior to the first 4 cycles with ICB and before the first tumour assessment.ResultsWe discovered that the baseline levels of CD45RO⁺CD8⁺ T cells significantly differed among the patients. Thirteen (43%) of our patients had normal baseline levels of CD45RO⁺CD8⁺ T cells, whereas 17 (57%) patients were low on CD45RO⁺CD8⁺ T cells. The baseline levels of CD45RO⁺CD8⁺ T cells correlated significantly with the response to ipilimumab but not pembrolizumab. Patients with baseline levels of lower/equal 25% of CD45RO⁺CD8⁺ T cells did not respond to treatment with ipilimumab. Phenotyping the CD8⁺ T cells in patients treated with ipilimumab revealed an activated HLA-DR⁺CD25⁻ phenotype, implying antigen non-specific stimulation. The levels of the HLA-DR⁺CD25⁻CD8⁺ T cells were significantly higher in patients with a normal baseline of CD45RO⁺CD8⁺ T cells and even increased significantly during treatment. Furthermore, proliferation of melanoma antigen recognized by T cells 1 (MART-1)-specific CD8⁺ T cells was not observed. Patients with normal baseline levels of CD45RO⁺CD8⁺ T cells showed a significant longer overall survival when treated with ipilimumab but not pembrolizumab.ConclusionPatients with normal baseline levels of CD45RO⁺CD8⁺ T cells respond significantly more frequently to treatment with ipilimumab and the CD8⁺ T cells appear to be antigen non-specifically activated. The baseline level of CD45RO⁺CD8⁺ T cells represents a promising factor as biomarker for the prediction of the response to ipilimumab.     

Cancer cell-derived exosomal miR-20a-5p inhibits CD8+ T-cell function and confers anti-programmed cell death 1 therapy resistance in triple-negative breast cancer

Circulating miRNAs (cirmiRNAs) can be packaged into the exosomes, participating in intercellular communication, which affects the malignant progression and therapy resistance of triple-negative breast cancer (TNBC). Currently, immune checkpoint inhibitors that regulate T-cell function, especially antibodies against programmed cell death 1 (PD-1) or its ligand PD-L1, are emerging as new promising therapy for TNBC patients. However, only very limited patients showed complete or partial response to anti-PD-1 treatment. Dysfunction of CD8⁺ T cells is one of the key reasons for the immune escape of TNBC. The regulation of exosome-derived cirmiRNAs on CD8⁺ T cells in TNBC deserves more investigation. Here, the cirmiR-20a-5p level was significantly upregulated in the plasma of TNBC patients and culture supernatant of TNBC cells. High abundance of cirmiR-20a-5p was correlated with a worse prognosis of TNBC. cirmiR-20a-5p was secreted in the form of exosomes by TNBC cells. Exosomal cirmiR-20a-5p was internalized into CD8⁺ T cells and resulted into the dysfunction of CD8⁺ T. A mechanism study uncovered that cirmiR-20a-5p targeted the nuclear protein ataxia-telangiectasia (NPAT) and decreased NPAT expression in CD8⁺ T cells. An in vivo xenograft mouse model showed that cirmiR-20a-5p conferred TNBC to anti-PD-1 treatment resistance. Collectively, these findings indicated that cirmiR-20a-5p released by TNBC cells via exosome promotes cancer cell growth and leads to the immunosuppression by inducing CD8⁺ T cell dysfunction. This study suggests that targeting cirmiR-20a-5p might be a novel strategy for overcoming the resistance of TNBC to anti-PD-1 immunotherapy.     

Stromal PD-L1–Positive Regulatory T cells and PD-1–Positive CD8-Positive T cells Define the Response of Different Subsets of Non–Small Cell Lung Cancer to PD-1/PD-L1 Blockade Immunotherapy

Introduction

Inhibition of programmed cell death-1 (PD-1) and its ligand programmed death ligand 1 (PD-L1) by using an immune checkpoint inhibitor has emerged as a promising immunotherapy for NSCLC. The correlation of PD-L1 expression in tumor cells with treatment outcomes has been reported in many pivotal trials; however, the relationship remains unclear. Here, we demonstrate that those patients with both high density of PD-1–positive CD8 and PD-L1–positive CD4-positive CD25-positive (PD-1^hi PD-L1^hi) regulatory T cells (Tregs) have a better response to PD1/PD-L1 blockade.

Colorectal cancer exosomes induce lymphatic network remodeling in lymph nodes

The lymphatic network remodeling may guide tumor metastasis in a sentinel lymph node (SLN). Although tumor-derived exosomes have been demonstrated to modify the microenvironment in adjacent organs and initiate a premetastatic niche, their influence on the lymphatic network in SLNs has not been explained. Here, we show that CT26 cell exosomes (Exo) promote the proliferation of lymphatic endothelial cells and the formation of lymphatic network in SLN, facilitating the SLN metastasis of colorectal cancer (CRC). Uptake of Exo by macrophages promoted VEGFC secretion both in vivo and in vitro. Exo increased the frequency of F4/80⁺ macrophages in the SLN. Macrophage ablation by clodrosome prevented the exosomal effect on lymphatic network remodeling and SLN metastasis. Exosomal IRF-2 was highly expressed in serum exosomes isolated from CRC patients with LN metastasis relative to patients without LN metastasis and healthy controls. Mechanistically, exosomal IRF-2 induced the release of VEGFC by macrophages. An IRF-2 knockdown attenuated the lymphatic network remodeling in the SLN and suppressed the SLN metastasis. Our data suggest that exosomal IRF-2 remodels the lymphatic network in an SLN and may predict the development of CRC LN metastases.     

Clinical Significance of PD-L1 Expression and CD8-Positive Tumor-Infiltrating Lymphocytes in Patients with Cavitary Lung Adenocarcinoma

Cavitary lung cancer is a rare type of lung cancer. Generally, the relationship between cavitary lung adenocarcinoma (LUAD) and specific immune checkpoints remains unknown. In this study, we aimed to detect the expression of programmed cell death ligand-1(PD-L1) and the density of CD8-positive (CD8⁺) tumor-infiltrating lymphocytes (TILs) to evaluate their clinicopathological significance in the case of patients with cavitary LUAD. This study included 65 patients with cavitary LUAD. Patient specimens were obtained from surgery. The expression of PD-L1 protein and CD8⁺ TIL status was detected by traditional immunohistochemistry and multiplex quantitative immunofluorescence technology. The correlation of PD-L1 expression and CD8⁺ TIL status was assessed along with clinicopathological parameters. This included evaluation of overall survival in cavitary LUAD patients based on the follow-up data. High expression of PD-L1 protein was detected in the cancerous tissues of cavitary LUAD patients, whose positive rate was recorded at 44.6% (29/65). PD-L1 expression level was significantly related with the lymph node (P = 0.001), TNM stage (P = 0.024), and CD8⁺ TIL status (rs = −0.272, P = 0.025). High PD-L1 expression indicated high mortality rate (P < 0.001); however, the CD8⁺ TIL group showed better survival in cavitary LUAD patients (P = 0.011). This phenotype, with high PD-L1 expression and low CD8⁺ TILs, can predict poorer overall survival of patients with cavitary LUAD compared with the other phenotypes. Moreover, CD8⁺ TIL level was an independent good prognosis factor. Initially, we reported that PD-L1 is upregulated in cavitary LUAD patients and that high expression of PD-L1 negatively correlates with CD8⁺ TIL status. High PD-L1 expression and low CD8⁺ TILs can predict decreased overall survival of patients with cavitary LUAD.     

Expression of PD-L1 in tumor-associated nerves correlates with reduced CD8+ tumor-associated lymphocytes and poor prognosis in prostate cancer

To investigate immune profile consisting of stromal PD-L1 expression, inhibitory or non-T-cell inflamed tumor microenvironment that may predict response to anti-PD-L1/PD-1 immunotherapy in prostate cancer, we validated the specificity of a PD-L1 monoclonal antibody (E1L3N) and identified PD-L1 specific expression in prostatic stromal nerve cells. PD-L1 expression was analyzed in 73 primary prostate cancers and 7 castration-resistant prostate cancers (CRPC) by immunohistochemistry (IHC) and resulting data from primary prostate cancers were correlated with tumor-associated lymphocytes (TALs), clinicopathological characteristics and clinical outcome. PD-L1 was expressed in the tumor cells in only one primary prostate cancer case and none of the CRPC. However, PD-L1 was frequently observed in the nerve branches in the tumor-associated stroma (69 of 73 cases, 94.5%), supported by colocalization with axonal marker PGP9.5. FoxP3-, CD3- and CD8-positive T lymphocytes were observed in 74.6% (47/63), 98.4% (62/63) and 100% (61/61) of the cases, respectively. The density of PD-L1⁺ tumor-associated nerves (TANs) was inversely correlated with that of CD8⁺ TALs. Higher density of PD-L1⁺ TANs was significantly associated with biochemical recurrence (BCR) in Kaplan–Meier survival analysis (p = 0.016). In both univariate and multivariate Cox analysis, the density of PD-L1⁺ TANs was independently prognostic of BCR. In conclusion, PD-L1 expression is rare in prostate tumor cells but prevalent in TANs and negatively correlated with CD8⁺ TALs. Neuro-immunological interaction may be a contribution to immune-suppressive microenvironment. Combinatorial treatment regimen designs to neural PD-L1 and TALs should be warranted in future clinical application of anti-PD-L1/PD-1 immunotherapy in prostate cancer.     

Concurrent High PD-L1 Expression and CD8+ Immune Cell Infiltration Predict PD-1 Blockade Efficacy in Advanced EGFR-Mutant NSCLC Patients

ObjectivesThe effectiveness of PD-1 blockade therapy in advanced epidermal growth factor receptor (EGFR)-mutant non-small cell lung cancer (NSCLC) is limited. We investigated whether patient characteristics, PD-L1 expression, and immune cell (IC) status in the tumor microenvironment (TME) were associated with PD-1 blockade therapy outcomes.Materials and methodsWe retrospectively reviewed patients with advanced EGFR-mutant NSCLC treated with PD-1 blockade (nivolumab or pembrolizumab) between January 2016 and March 2018. The PD-L1 expression tumor proportion score (TPS) and types and distribution of ICs (CD8, PD-1, CD204, tumoral, and stromal) in the TME were analyzed.ResultsAmong 57 EGFR-mutant NSCLC patients treated with PD-1 blockade, 39 patients had sufficient tissues for analyzing the TME. The overall response rate (ORR) of PD-1 blockade was 12.3%. Only tumoral CD8 positive (CD8⁺) IC status was significantly associated with the response (median tumoral CD8⁺ICs: 299/mm² vs. 115/mm², P < .01). Among the 6 patients with concurrent high PD-L1 expression (TPS: ≥ 50%)/high tumoral CD8⁺ ICs (≥ 205/mm²), 5 (83.3%) showed a response and a significantly longer progression-free survival (PFS) (PFS: 9.4M vs. 1.8M, P < .01). In contrast, none of the 7 patients with high PD-L1 expression/low tumoral CD8⁺ICs (<205/mm²) showed a response.ConclusionConcurrent high PD-L1 expression and high tumoral CD8⁺ ICs could predict the response and longer PFS of PD-1 blockade therapy in EGFR-mutant patients.     

Chemokine C-C motif ligand 21 synergized with programmed death-ligand 1 blockade restrains tumor growth

Programmed death-ligand 1 (PD-L1) blockade has revolutionized the prognosis of several cancers, but shows a weak effect on pancreatic cancer (PC) due to poor effective immune infiltration. Chemokine C-C motif ligand 21 (CCL21), a chemokine promoting T cell immunity by recruiting and colocalizing dendritic cells (DCs) and T cells, serves as a potential antitumor agent in many cancers. However, its antitumor response and mechanism combined with PD-L1 blockade in PC remain unclear. In our study, we found CCL21 played an important role in leukocyte chemotaxis, inflammatory response, and positive regulation of PI3K-AKT signaling in PC using Metascape and gene set enrichment analysis. The CCL21 level was verified to be positively correlated with infiltration of CD8⁺ T cells by the CIBERSORT algorithm, but no significant difference in survival was observed in either The Cancer Genome Atlas or the International Cancer Genome Consortium cohort when stratified by CCL21 expression. Additionally, we found the growth rate of allograft tumors was reduced and T cell infiltration was increased, but tumor PD-L1 abundance elevated simultaneously in the CCL21-overexpressed tumors. Then, CCL21 was further verified to increase tumor PD-L1 level through the AKT-glycogen synthase kinase-3β axis in human PC cells, which partly impaired the antitumor T cell immunity. Finally, the combination of CCL21 and PD-L1 blockade showed superior synergistic tumor suppression in vitro and in vivo. Together, our findings suggested that CCL21 in combination with PD-L1 blockade might be an efficient and promising option for the treatment of PC.     

The tetraspanins CD151 and Tspan8 are essential exosome components for the crosstalk between cancer initiating cells and their surrounding

Tspan8 and CD151 are metastasis-promoting tetraspanins and a knockdown (kd) of Tspan8 or CD151 and most pronounced of both tetraspanins affects the metastatic potential of the rat pancreatic adenocarcinoma line ASML. Approaching to elaborate the underlying mechanism, we compared ASML^wt, -CD151^kd and/or Tspan8^kd clones. We focused on tumor exosomes, as exosomes play a major role in tumor progression and tetraspanins are suggested to be engaged in exosome targeting.ASML-CD151/Tspan8^kd cells poorly metastasize, but regain metastatic capacity, when rats are pretreated with ASML^wt, but not ASML-CD151^kd and/or -Tspan8^kd exosomes. Both exosomal CD151 and Tspan8 contribute to host matrix remodelling due to exosomal tetraspanin-integrin and tetraspanin-protease associations. ASML^wt exosomes also support stroma cell activation with upregulation of cytokines, cytokine receptors and proteases and promote inflammatory cytokine expression in hematopoietic cells. Finally, CD151-/Tspan8-competent exosomes support EMT gene expression in poorly-metastatic ASML-CD151/Tspan8^kd cells. These effects are not seen or are weakened using ASML-CD151^kd or -Tspan8^kd exosomes, which is at least partly due to reduced binding/uptake of CD151- and/or Tspan8-deficient exosomes.Thus, CD151- and Tspan8-competent tumor exosomes support matrix degradation, reprogram stroma and hematopoietic cells and drive non-metastatic ASML-CD151/Tspan8^kd cells towards a motile phenotype.     

RAB27B-activated secretion of stem-like tumor exosomes delivers the biomarker microRNA-146a-5p,which promotes tumorigenesis and associates with an immunosuppressive tumor microenvironment in colorectal cancer

The dynamic cell–cell communication is essential for tissue homeostasis in normal physiological circumstances and contributes to a diversified tumor microenvironment. Although exosomes are extracellular vesicles that actively participate in cell–cell interaction by shutting cellular components, impacts of tumor exosomes in the context of cancer stemness remain elusive. Here, we expand colorectal cancer stem cells (CRCSCs) as cancer spheroids and demonstrate that the β-catenin/Tcf-4-activated RAB27B expression is required for the secretion of CRCSC exosomes. In an exosomal RNA sequencing analysis, a switch of exosomal RNA species from retrotransposons to microRNAs (miRNAs) is identified upon expanding CRCSCs. miRNA-146a-5p (miR-146a) is the major miRNA in CRCSC exosomes and exosomal miR-146a promotes stem-like properties and tumorigenicity by targeting Numb in recipient CRC cells. Among 53 CRC patients, those with abundant exosomal miR-146a expression in serum exhibits higher miR-146a^High/Numb^Low CRCSC traits, an increased number of tumor-filtrating CD66(+) neutrophils and a decreased number of tumor-infiltrating CD8(+) T cells. Our study elucidates a unique mechanism of tumor exosome-mediated stemness expansion.     

The immune response‐related mutational signatures and driver genes in non‐small‐cell lung cancer

Immune checkpoint blockade (ICB) therapy has achieved remarkable clinical benefit in non‐small‐cell lung cancer (NSCLC), but our understanding of biomarkers that predict the response to ICB remain obscure. Here we integrated somatic mutational profile and clinicopathologic information from 113 NSCLC patients treated by ICB (CTLA‐4/PD‐1). High tumor mutation burden (TMB) and neoantigen burden were identified significantly associated with improved efficacy in NSCLC immunotherapy. Furthermore, we identified apolipoprotein B mRNA editing enzyme, catalytic polypeptide‐like (APOBEC) mutational signature was markedly associated with responding of ICB therapy (log‐rank test, P = .001; odds ratio (OR), 0.18 [95% CI, 0.06‐0.50], P < .001). The association with progression‐free survival remained statistically significant after controlling for age, sex, histological type, smoking, PD‐L1 expression, hypermutation, smoking signature and mismatch repair (MMR) (HR, 0.30 [95% CI, 0.12‐0.75], P = .010). Combined high TMB with APOBEC signature preferably predict immunotherapy responders in NSCLC cohort. The CIBERSORT algorithm revealed that high APOBEC mutational activity samples were associated with increased infiltration of CD4 memory activated T cells, CD8⁺ T cells and natural killer (NK) cells, but reduced infiltration of regulatory T cells. Besides, individual genes mutation of IFNGR1 or VTCN1 were only found in responders; however, the PTEN mutation was only found in non‐responders (Fisher's exact test, all P < .05). These findings may be applicable for guiding immunotherapy for patients with NSCLC.     

Programmed cell death ligand-1 (PD-L1) expression combined with CD8 tumor infiltrating lymphocytes density in non-small cell lung cancer patients

Cancer immunotherapy targeting programmed cell death-1/programmed cell death ligand-1 (PD-1/PD-L1) pathway has shown promising results in treatment of non-small cell lung cancer (NSCLC) patients. T cells play a major role in tumor-associated immune response. This study aimed to investigate PD-L1 expression alone and combined with CD8 tumor infiltrating lymphocytes (TILs) density in relation to clinicopathologic parameters and survival in NSCLC patients. Immunohistochemical analysis was used to evaluate PD-L1 expression and CD8 TILs density in 55 NSCLC patients. PD-L1 immunopositivity was detected in 36 (65.5%) of NSCLC cases. PD-L1 expression was significantly related to high tumor grade (p value?=?0.038) and low CD8 TILs density (p value?=?0.004), whereas no significant relations were detected between PD-L1 expression and tumor stage (p value?=?0.121), overall survival (OS) (p value?=?0.428) and progression-free survival (PFS) (p value?=?0.439). Among PD-L1/CD8 TILs density groups, PD-L1⁺/CD8^Low group was significantly associated with high tumor grade compared to PD-L1^?/CD8^high group (pairwise p?=?0.016). PD-L1⁺/CD8^Low group was significantly related to advanced tumor stage compared to PD-L1⁺/CD8^high and PD-L1^?/CD8^Low groups (pairwise p?=?0.001 and 0.013 respectively). PD-L1^?/CD8^high group exhibited the best OS and PFS whereas PD-L1⁺/CD8^low group had the poorest OS and PFS (p value?=?0.032 and 0.001 respectively). Assessment of PD-L1 combined with CD8 TILs density, instead of PD-L1 alone, suggested important prognostic relevance in NSCLC patients.