Targeting KIFC1 Promotes Senescence in Soft Tissue Sarcoma via FXR1-Dependent Regulation of MAD2L1 mRNA Stability.

Patients diagnosed with soft tissue sarcoma (STS) often present at intermediate to advanced stages, with inherently limited therapeutic options available. There is an urgent need to identify novel therapeutic targets. In this study, by screening STS data from the Cancer Genome Atlas (TCGA) and Genotype Tissue Expression (GTEx) databases, KIFC1 is identified as a potential biomarker and a promising therapeutic target for STS. Notably, a significant increase in KIFC1 levels, which exhibited a strong correlation with a poor prognosis in STS patients is observed. The findings revealed that knockout of KIFC1 suppressed STS growth both in vitro and in vivo. Furthermore, KIFC1 is found to regulate cellular senescence in STS, which has not been reported before. that targeting KIFC1 induced cellular senescence via interacting with FXR1, an RNA-binding protein is discovered, thereby further stabilizing MAD2L1 mRNA in an m6A-dependent manner. Additionally, the suppression of KIFC1 markedly diminished the growth of patient-derived xenografts (PDX) and triggered senescence. This study provides the first evidence that KIFC1 inhibition induces cellular senescence through MAD2L1, underscoring KIFC1 as a novel prognostic biomarker and a potential therapeutic target for STS.

FGFR4-specific CAR-T cells with inducible caspase-9 suicide gene as an approach to treat rhabdomyosarcoma.

Metastatic rhabdomyosarcoma is associated with poor survival and unsatisfactory treatment outcomes. Therefore, new immunotherapeutic methods are urgently required. Fibroblast growth factor receptor 4 (FGFR4), a new therapeutic target for rhabdomyosarcoma, plays a crucial role in its onset and development. This study aimed to generate FGFR4 single-chain variable fragment-based chimeric antigen receptor (CAR) T cells without causing evident toxicity and incorporating an inducible caspase-9 (iCasp9) suicide gene system to enhance their safety. FGFR4 antigen expression was evaluated in normal murine tissues, normal human tissues, and specimens from patients with rhabdomyosarcoma. Combined with a 4-1BB co-stimulatory domain, a CD3ζ signaling domain, and an iCasp9 suicide gene, CAR-T cells with an FGFR4-specific single-chain variable fragment were developed. The specific cytotoxic effects, T-cell proliferation, cytokine secretion, apoptosis induction by chemical dimerization (AP20187), and toxicity of FGFR4 CAR-T cells were investigated in vitro and in vivo. FGFR4 CAR-T cells generated a variety of immune-promoting cytokines, including tumor necrosis factor α, interleukin 2, and interferon γ, and displayed effective cytotoxic activity against FGFR4-overexpressing rhabdomyosarcoma cells in vitro. FGFR4 CAR-T cells were relatively effective against FGFR4-overexpressing rhabdomyosarcoma, with tumor regression and poor survival in a subcutaneous xenograft model. The iCasp9 gene was incorporated into FGFR4 CAR-T cells and it was demonstrated that effective and reliable suicide gene activity depends on the administration of AP20187. By making use of the cross-reaction of FGFR4 CAR-T cells with murine FGFR4 in a syngeneic tumor model, this study found that FGFR4 CAR-T cells could regulate the growth of tumors without evident toxicity. Our study demonstrates that FGFR4 is a prospective target for CAR-T cell therapy in rhabdomyosarcoma without serious on-target off-tumor toxicity. FGFR4 CAR-T cells with the iCasp9 suicide gene system as a safety switch to limit toxicity may broaden the clinical applications of cellular therapy.

Anlotinib as a maintenance treatment for advanced soft tissue sarcoma after first-line chemotherapy (ALTER-S006): a multicentre, open-label, single-arm, phase 2 trial.

Background: No standard maintenance treatment has been obtained to prolong the response duration of soft tissue sarcoma (STS) after first-line chemotherapy. In this study, we aimed to evaluate the efficacy and safety of anlotinib as a maintenance treatment after chemotherapy in STS. Methods: In this multicentre, open-label, single-arm phase 2 trial, patients with advanced STS who achieved partial response or stable disease after first-line anthracycline-based chemotherapy were enrolled between April 2019 and January 2022. All patients received anlotinib as a maintenance treatment. The primary endpoint was progression-free survival (PFS) of anlotinib maintenance treatment. Other endpoints included overall survival (OS), objective response rate (ORR), disease control rate (DCR) and safety. This study is registered with ClinicalTrials.gov, NCT03890068. Findings: At the data cut-off date (August 8, 2022), 49 patients were enrolled, including 17 with liposarcoma (35%) and 15 with leiomyosarcoma (31%). After a median follow-up of 17.1 months (IQR 9.0-27.2), the median PFS from the beginning of maintenance treatment was 9.1 months (95% CI 5.7-12.5), and the median OS was not reached, and the 1-year OS rate for anlotinib maintenance treatment was 98.0%. The best ORR and DCR were 16% (8/49, 95% CI 7-30) and 94% (46/49, 95% CI 83-99), respectively. Most of the treatment-related adverse events were grade 1-2. Of the grade 3-4 adverse events, the most common were hypertension (10%) and hand-foot syndrome reaction (6%). Interpretation: Postchemotherapy maintenance treatment with anlotinib exhibits promising efficacy and tolerable toxicity in patients with advanced STS. Funding: Chia Tai Tianqing Pharmaceutical Group Co., Ltd., the National Key Research and Development Program of China, and the National Natural Science Foundation of China.

Phase 1 clinical trial to assess safety and efficacy of NY-ESO-1-specific TCR T cells in HLA-A∗02:01 patients with advanced soft tissue sarcoma.

New York esophageal squamous cell carcinoma-1 (NY-ESO-1)-specific T cell receptor (TCR) T cell therapy is effective in tumors with NY-ESO-1 expression, but a safe and effective TCR-T cell therapeutic protocol remains to be improved. Here, we report a phase 1 investigational new drug clinical trial with TCR affinity-enhanced specific T cell therapy (TAEST16001) for targeting NY-ESO-1. Enrolled patients receive TAEST16001 cell infusion after dose-reduced lymphodepletion with cyclophosphamide (15 mg/kg/day × 3 days) combined with fludarabine (20 mg/m2/day × 3 days), and the TCR-T cells are maintained with low doses of interleukin-2 injection post-adoptive transfer. Analysis of 12 patients treated with the regimen demonstrates no treatment-related serious adverse events. The overall response rate is 41.7%. The median progression-free survival is 7.2 months, and the median duration of response is 13.1 months. The protocol of TAEST16001 cells delivers a safe and highly effective treatment for patients with advanced soft tissue sarcoma (ClinicalTrials.gov: NCT04318964).

Genomic Profiling of Radiation-Induced Sarcomas Reveals the Immunologic Characteristics and Its Response to Immune Checkpoint Blockade.

PURPOSE: Radiation-induced sarcomas (RIS) have a poor prognosis and lack effective treatments. Its genome and tumor microenvironment are not well characterized and need further exploration. EXPERIMENTAL DESIGN: Here, we performed whole-exome sequencing (WES) and mRNA sequencing (mRNA-seq) on patients with RIS and primary sarcomas (WES samples 46 vs. 48, mRNA-seq samples 16 vs. 8, mainly in head and neck), investigated the antitumor effect of programmed cell death protein 1 (PD-1) blockade in RIS patient-derived xenograft models, and analyzed clinical data of patients with RIS treated with chemotherapy alone or combined with an anti-PD-1 antibody. RESULTS: Compared with primary sarcomas, RIS manifested different patterns of copy-number variations, a significantly higher number of predicted strong MHC-binding neoantigens, and significantly increased immune cell infiltration. Clinical data showed that the combinatorial use of chemotherapy and PD-1 blockade achieved a higher objective response rate (36.67% vs. 8.00%; P = 0.003), longer overall survival (31.9 months vs. 14.8 months; P = 0.014), and longer progression-free survival (4.7 months vs. 9.5 months; P = 0.032) in patients with RIS compared with single chemotherapy. CONCLUSIONS: Elevated genomic instability and higher immune cell infiltrations were found in RIS than in primary sarcomas. Moreover, higher efficacy of chemotherapy plus PD-1 blockade was observed in animal experiments and clinical practice. This evidence indicated the promising application of immune checkpoint inhibitors in the treatment of RIS.

The inflammatory-nutritional score and nomogram for R0 resected head and neck soft tissue sarcoma.

OBJECTIVES: To explore the predictive value of inflammatory-nutritional score (INS) and a nomogram for survivals in head and neck soft tissue sarcoma (HNSTS) patients with negative resection margins (R0). METHODS: Clinical characteristics and hematological features of 315 HNSTS patients underwent R0 surgery were analyzed. RESULTS: The 5-year overall survival (OS) rate, 3-year recurrence-free survival rate and disease-free survival (DFS) rate were 77.3%, 61.0% and 55.4%, respectively. High INS was associated with a deep tumor location (p < 0.001), high tumor grade (p < 0.001), and advanced AJCC stage (p < 0.001). The low-risk group (INS 0) exhibited a higher 5-year OS rate and 3-year DFS rate than others (87.6% vs. 81.3% vs. 53.3%, p < 0.001; 62.2% vs. 56.9% vs. 37.9%, p = 0.007). The INS (p = 0.023), tumor depth (p < 0.001), pT classification (p = 0.022), pN classification (p < 0.001) and tumor grade (p < 0.001) were independent survival predictors. Moreover, a novel nomogram for predicting OS was generated and assessed by the concordance index, exhibiting a better performance than the p7TNMG classification alone (p < 0.001). CONCLUSIONS: For R0 resected HNSTS patients, the oncological outcomes can be predicted using the INS system and a specific nomogram.

Phase I study of pegylated liposomal doxorubicin and cisplatin in patients with advanced osteosarcoma.

PURPOSE: The repeated use of doxorubicin is limited due to dose-limiting cardiac toxicity. Pegylated liposomal doxorubicin (PEG-LD, Duomeisu) has a reduced cardiac toxicity. This phase I study aimed to investigate the maximum tolerated doses (MTDs) and dose-limiting toxicities (DLTs) of the PEG-LD and cisplatin combination in patients with metastatic and recurrent osteosarcoma. METHODS: Patients were given PEG-LD at a dose of 40, 50, or 60 mg/m2 on day 1 of each 21-day cycle, according to a 3 + 3 approach for dose escalation. Cisplatin was administered as a fixed dose of 100 mg/m2 for every cycle. Toxicities and tumor response were observed. RESULTS: A total of 15 patients were enrolled in this trial, and nine of the patients had received prior doxorubicin. The MTD of PEG-LD was reached at 50 mg/m2 in this regimen, with neutropenic fever and stomatitis as DTLs. The main adverse event (AE) was myelosuppression. The most common non-hematological AEs were vomiting, hypoproteinemia, stomatitis and transient sinus arrhythmia. Grade 3-4 toxicity was neutropenia, leukopenia, thrombocytopenia, anemia and stomatitis in the whole cohort. All the AEs were relieved after symptomatic and supportive treatment. Totally, the overall response rate was 13.3% and disease control rate was 66.7%. For the six patients who have not received prior doxorubicin, one partial response and five stable diseases were observed. CONCLUSION: We provide the data showing that PEG-LD 50 mg/m2 combined with cisplatin 100 mg/m2 demonstrated an acceptable safety profile and promising clinical activity in advanced osteosarcoma, which merits further evaluation in phase II studies. TRIAL REGISTRATION: ChiCTR1900021550.

New nomograms to predict overall and cancer-specific survival of angiosarcoma.

OBJECTIVE: This study was designed to establish and validate promising and reliable nomograms for predicting the survival of angiosarcoma (AS) patients. METHODS: The Surveillance, Epidemiology, and End Results database was queried to collect the clinical information of 785 AS patients between 2004 and 2015. Data were split into a training cohort (n = 549) and a validation cohort (n = 236) without any preference. Univariate Cox and multivariate Cox regression analyses were performed to analyze the clinical parameters. Independent prognostic factors were then identified. Two nomograms were constructed to predict overall survival (OS) and cancer-specific survival (CSS) at 3 and 5 years. Finally, the models were evaluated using concordance indices (C-indices), calibration plots, and decision curve analysis (DCA). RESULTS: Based on the inclusion and exclusion criteria, 785 individuals were included in this analysis. Univariate and multivariate Cox regression analyses revealed that age, tumor size, and stage were prognostic factors independently associated with the OS of AS. Tumor site, tumor size, and stage were associated with the CSS of AS. Based on the statistical results and clinical significance of variables, nomograms were built. The nomograms for OS and CSS had C-indices of 0.666 and 0.654, respectively. The calibration curves showed good agreement between the predictive values and the actual values. DCA also indicated that the nomograms were clinically useful. CONCLUSION: We established nomograms with good predictive ability that could provide clinicians with better predictions about the clinical outcomes of AS patients.

Frequent amplification of HDAC genes and efficacy of HDAC inhibitor chidamide and PD-1 blockade combination in soft tissue sarcoma.

BACKGROUND: The advent of immune checkpoint therapy has been a tremendous advance in cancer treatment. However, the responses are still insufficient in patients with soft tissue sarcoma (STS). We aimed to identify rational combinations to increase the response to immune checkpoint therapy and improve survival. METHODS: Whole-exome sequencing (WES) was performed in 11 patients with liposarcoma. Somatic copy number alterations (SCNAs) were analyzed at the gene level to identify obvious amplification patterns in drug-target genes. The expression and prognostic value of class I histone deacetylases (HDACs) was evaluated in 49 patients with sarcoma in our center and confirmed in 263 sarcoma samples from The Tumor Cancer Genome Atlas (TCGA) database. Q-PCR, flow cytometry and RNA-seq were performed to determine the correlations between class I HDACs, chidamide and PD-L1 in vitro and in vivo. The efficacy of combining chidamide with PD-1 blockade was explored in an immunocompetent murine model and a small cohort of patients with advanced sarcoma. Western blot, ChIP assay and dual luciferase assessment were applied in the mechanistic study. RESULTS: The HDAC gene family was frequently amplified in STS. SCNAs in the HDAC gene family were extensively amplified in 8 of 11 (73%) patients with liposarcoma, based on a drug-target gene set, and we verified amplification in 76.65% (197/257) of cases by analyzing TCGA sarcoma cohort. Class I HDAC expression is associated with a poor prognosis for patients with STS, and its inhibition is responsible for promoting apoptosis and upregulating of programmed cell death ligand 1 (PD-L1). The HDAC class I inhibitor chidamide significantly increases PD-L1 expression, increased the infiltration of CD8+ T cells and reduced the number of MDSCs in the tumor microenvironment. The combination of chidamide with an anti-PD-1 antibody significantly promotes tumor regression and improves survival in a murine model. Moreover, chidamide combined with the anti-PD-1 antibody toripalimab is effective in patients with advanced and metastatic sarcoma, and the side effects are tolerable. Mechanistically, chidamide increases histone acetylation at the PD-L1 gene through the activation of the transcriptional factor STAT1. CONCLUSIONS: The combination of chidamide and anti-programmed cell death 1 (PD-1) therapy represents a potentially important strategy for STS.

Tumor metastasis: Mechanistic insights and therapeutic interventions.

Cancer metastasis is responsible for the vast majority of cancer-related deaths worldwide. In contrast to numerous discoveries that reveal the detailed mechanisms leading to the formation of the primary tumor, the biological underpinnings of the metastatic disease remain poorly understood. Cancer metastasis is a complex process in which cancer cells escape from the primary tumor, settle, and grow at other parts of the body. Epithelial-mesenchymal transition and anoikis resistance of tumor cells are the main forces to promote metastasis, and multiple components in the tumor microenvironment and their complicated crosstalk with cancer cells are closely involved in distant metastasis. In addition to the three cornerstones of tumor treatment, surgery, chemotherapy, and radiotherapy, novel treatment approaches including targeted therapy and immunotherapy have been established in patients with metastatic cancer. Although the cancer survival rate has been greatly improved over the years, it is still far from satisfactory. In this review, we provided an overview of the metastasis process, summarized the cellular and molecular mechanisms involved in the dissemination and distant metastasis of cancer cells, and reviewed the important advances in interventions for cancer metastasis.

Chimeric antigen receptor-modified T-cell therapy for platelet-derived growth factor receptor α-positive rhabdomyosarcoma.

BACKGROUND: New immunotherapeutic approaches are urgently needed for metastatic rhabdomyosarcoma, which is associated with poor survival and unsatisfactory treatment outcomes. Platelet-derived growth factor receptor α (PDGFRA) plays an essential role in the onset and development of rhabdomyosarcoma and is a new potential therapeutic target for rhabdomyosarcoma. The objective of this study was to generate humanized PDGFRA single-chain variable fragment-based chimeric antigen receptor (CAR)-modified T cells (CAR-T cells) against PDGFRA-positive rhabdomyosarcoma. METHODS: PDGFRA antigen expression was evaluated in specimens from patients with rhabdomyosarcoma. CAR-T cells containing a PDGFRA-specific single-chain variable fragment was developed in combination with a 4-1BB costimulatory domain and a CD3-ζ signaling domain. Specific cytotoxic effects of PDGFRA CAR-T cells, T-cell proliferation, and cytokine secretion were investigated in vitro and in vivo. RESULTS: PDGFRA CAR-T cells produced large amounts of immune-promoting cytokines, including interleukin 2, tumor necrosis factor α, and interferon γ, and exhibited efficient cytotoxic activity toward human PDGFRA-overexpressing rhabdomyosarcoma cells in vitro. In a subcutaneous xenograft model, CAR-T cells were more effective against PDGFRA-overexpressing rhabdomyosarcoma than against rhabdomyosarcoma with low PDGFRA expression in terms of tumor regression and patient survival. Expanded CAR-T cells also were detected in peripheral blood. CONCLUSIONS: The current study demonstrates for the first time that the PDGFRA antigen is a promising target for CAR-T-cell therapy in rhabdomyosarcoma and likely in a wide spectrum of other PDGFRA-expressing cancers.

ALKATI interacts with c-Myc and promotes cancer stem cell-like properties in sarcoma.

Soft tissue sarcoma (STS) is a highly malignant tumor with limited targeted therapies. A novel anaplastic lymphoma kinase (ALK) transcript, ALKATI, was identified recently and could be targeted by ALK inhibitors in melanoma. However, the clinical and functional role of aberrant ALKATI expression in STS remains unknown. Here we demonstrate that as a new ALK transcript, ALKATI is frequently found in STS. ALKATI expression correlates with a lower probability of progression-free survival in STS patients. Compared with the other ALK isoforms, ALKATI expresses not only in the cytoplasm, but also in the nucleus of sarcoma cells. Functionally, overexpression of ALKATI promoted cancer stem cell (CSC)-like properties in sarcoma cells by promoting sphere formation and upregulating the expression of stem cell markers. Moreover, the ALK inhibitors not only suppressed the oncogenic functions of ALKATI but also attenuated ALKATI-induced CSC-like properties by reducing the expression of stem cell markers such as c-Myc, ABCG2, BMI1, and OCT4 both in vitro and in vivo. Furthermore, ALKATI interacted with c-Myc and increased the binding of c-Myc to the ABCG2 promoter, resulting in the induction of stem cell-like properties. Together, these findings indicate that ALKATI may be a potential prognostic marker and therapeutic target for STS patients harboring such ALK aberrations.

The Impact of Unplanned Excision on the Outcomes of Patients With Soft Tissue Sarcoma of the Trunk and Extremity: A Propensity Score Matching Analysis.

BACKGROUND: Unplanned excision (UPE) of soft tissue sarcoma (STS) is often chosen in the early phase by general physicians without any radiological evaluation. PURPOSE: The present study aimed to evaluate the impact of UPE on the clinical outcomes of patients with STS of the trunk and extremity. MATERIALS AND METHODS: Patients with STS of the trunk and extremity who underwent R0 resection between 1998 and 2016 were included and divided into the UPE and planned excision (PE) groups. Propensity score matching (PSM) was used to control the selection bias. The endpoints were disease-specific survival (DSS), local recurrence-free survival (LRFS), and metastasis-free survival (MFS). RESULTS: In total, 458 patients (277 males, 181 females; median age: 43 years) were included: 329 (71.8%) in the PE group and 129 (28.2%) in the UPE group. The follow-up time ranged from 7.1 to 313.78 months, with a median of 112.18 months. UPE patients were more likely to have a smaller or superficial lesion and were more frequently administered adjuvant therapy. After PSM, compared with the PE group, the UPE group had a longer LRFS (P=0.015), but there was no difference between the two groups regarding DSS and MFS. Residual disease was observed in 77.5% of the re-resected specimens in the UPE group and was a risk factor for DSS (P = 0.046) and MFS (P = 0.029) but was not associated with local recurrence (LR) (P=0.475) or LRFS (P=0.334). Moreover, we found no difference in DSS, LRFS or MFS according to the interval from UPE to definitive resection. CONCLUSION: STS treated with UPE had distinct characteristics. Patients who undergo UPE followed by an additional wide R0 resection have similar oncological survival compared to patients who undergo an initial PE, although the high incidence of residual tumor in the UPE group leads to an unfavorable clinical course.

LAG-3 expression on tumor-infiltrating T cells in soft tissue sarcoma correlates with poor survival.

OBJECTIVE: To elucidate the role and prognostic significance of lymphocyte activation-gene-3 (LAG-3) in soft tissue sarcoma (STS). METHODS: The expression of LAG-3 in patient and matched normal blood samples was analyzed by flow cytometry. The localization and prognostic values of LAG-3+ cells in 163 STS patients were analyzed by immunohistochemistry. In addition, the expression of tumor-infiltrating CD3+ T, CD4+ T, and CD8+ T cells and their role in the prognosis of STS were evaluated by immunohistochemistry. The effect of LAG-3 blockade was evaluated in an immunocompetent MCA205 fibrosarcoma mouse model. RESULTS: Peripheral CD8+ and CD4+ T cells from STS patients expressed higher levels of LAG-3 than those from healthy donors. LAG-3 expression in STS was significantly associated with a poor clinical outcome (P = 0.038 ) and was correlated with high pathological grade (P < 0.001), advanced tumor stage ( P = 0.016). Additionally, LAG-3 expression was highly correlated with CD8+ T-cell infiltration (r = 0.7034, P < 0.001). LAG-3 was expressed in murine tumor-infiltrating lymphocytes, and its blockade decreased tumor growth and enhanced secretion of interferon-gamma by CD8 + and CD4+ T cells. CONCLUSIONS: LAG-3 blockade may be a promising strategy to improve the effects of targeted therapy in STS.

Comparison of the MAID (AI) and CAV/IE regimens with the predictive value of cyclic AMP-responsive element-binding protein 3 like protein 1 (CREB3L1) in palliative chemotherapy for advanced soft-tissue sarcoma patients.

Background: Palliative chemotherapy is currently the first-line treatment for advanced soft tissue sarcoma. The purpose of this study was to compare the efficacies of the MAID (AI) and CAV/IE alternating regimens in advanced soft-tissue sarcoma patients. Since resistances to ADM-based chemotherapy and toxicity from doxorubicin are frequently observed in clinical practice, we investigated the association between CREB3L1 expression and survival in advanced soft-tissue sarcomas patients treated with doxorubicin-based palliative chemotherapy. Methods: The cohort under investigation comprised 152 patients who underwent doxorubicin-based first-line palliative chemotherapy for advanced soft-tissue sarcoma at our institution between January 2010 and April 2017. Immunohistochemical analysis and the reverse transcription polymerase chain reaction were used to determine the expression of CREB3L1 in soft-tissue sarcoma specimens prior to first-line palliative chemotherapy. Univariate and multivariate analyses were performed on chemotherapy regimens and CREB3L1 expression levels. The relationship between CREB3L1 expression and survival was also analyzed. Results: The CAV/IE alternating regimen yielded favorable outcomes for response and survival in patients compared with those who received MAID (AI) treatment. The most common toxicity of grades 3 and 4 was leukopenia (58.5 % in the MAID (AI) regimen; 37.1 % in the CAV/IE regimen). The incidence of febrile neutropenia after CAV/IE treatment (7.1 %) was lower than after MAID (AI) treatment (13.4 %). Grade 3 neuralgia was observed in 1.2 % of patients receiving the MAID regimen versus 8.6 % in patients receiving the CAV/IE regimen. High CREB3L1 expression was observed in 48 of 152 patients (31.6 %). Overall survival was significantly higher for CREB3L1 high-expression patients than for CREB3L1 low-expression patients, especially for those also treated with the MAID (AI) regimen. The CREB3L1 expression level was identified as an independent prognostic factor for survival by multivariate analysis. Conclusions: Our study suggests that the CAV/IE alternating regimen may be associated with a better response and more favorable survival than the MAID (AI) regimen in advanced soft-tissue sarcoma patients. Furthermore, the CREB3L1 expression level may predict the efficacy and survival of doxorubicin-based palliative chemotherapy for advanced soft-tissue sarcoma.

PD-L1 Expression Is Associated with FOXP3+ Regulatory T-Cell Infiltration of Soft Tissue Sarcoma and Poor Patient Prognosis.

Background: Programmed death ligand-1(PD-L1) functions as a negative mediator of immune response through different pathways in anti-tumor immunity. Recent studies have reported that PD-L1 plays a pivotal role in the function of regulatory T-cells (Tregs). Although increases in FOXP3+ Tregs infiltration and PD-L1 expression have been revealed in several cancers, their correlation with soft tissue sarcoma remains unknown. Methods: We included 163 cases of soft tissue sarcoma who were diagnosed and underwent extensive and radical resection at the Sun Yat-sen University Cancer Center, Guangzhou, China, from 2000-2010. PD-L1 and FOXP3 expression was evaluated by immunohistochemistry. Correlation between their expressions and associations with clinicopathological features were studied. Results: Among 163 STS samples, 19 (11.7%) exhibited PD-L1 positivity, and 41 (25.2%) cases expressed high FOXP3+ Treg infiltration. Significant correlation between PD-L1 expression and FOXP3+Treg infiltration in STS was identified (r=0.450, p<0.001). In univariate analysis, PD-L1 expression was significantly associated with high tumor grade and the age of patients, while the presence of FOXP3+ in tumor infiltrating Tregs was significantly associated with the age of patients, high tumor stage, higher tumor grade and tumor depth. Multivariate analysis revealed PD-L1 and FOXP3 as independent prognostic indicators significantly associated with OS and DFS. Conclusions: Our study revealed that PD-L1 and FOXP3+Tregs may work synergistically in promoting immune evasion of the tumors in soft tissue sarcoma. A combined strategy to block PD-L1/PD-1 with simultaneous depletion of Tregs may show promise in enhancing the therapeutic efficacy of these patients.