Immune checkpoint inhibitors in sarcomas: in quest of predictive biomarkers

Prognostic characteristics of a six-gene signature based on ssGSEA in sarcoma

BACKGROUND

Sarcoma is a rare malignant tumor originating of the interstitial or connective tissue with a poor prognosis. Next-generation sequencing technology offers new opportunities for accurate diagnosis and treatment of sarcomas. There is an urgent need for new gene signature to predict prognosis and evaluate treatment outcomes.

METHODS

We used transcriptome data from the Cancer Genome Atlas (TCGA) database and single sample gene set enrichment analysis (ssGSEA) to explore the cancer hallmarks most associated with prognosis in sarcoma patients. Then, weighted gene coexpression network analysis, univariate COX regression analysis and random forest algorithm were used to construct prognostic gene characteristics. Finally, the prognostic value of gene markers was validated in the TCGA and Integrated Gene Expression (GEO) (GSE17118) datasets, respectively.

RESULTS

MYC targets V1 and V2 are the main cancer hallmarks affecting the overall survival (OS) of sarcoma patients. A six-gene signature including VEGFA, HMGB3, FASN, RCC1, NETO2 and BIRC5 were constructed. Kaplan-Meier analysis suggested that higher risk scores based on the six-gene signature associated with poorer OS (P < 0.001). The receiver Operating characteristic curve showed that the risk score based on the six-gene signature was a good predictor of sarcoma, with an area under the curve (AUC) greater than 0.73. In addition, the prognostic value of the six-gene signature was validated in GSE17118 with an AUC greater than 0.72.

CONCLUSION

This six-gene signature is an independent prognostic factor in patients with sarcoma and is expected to be a potential therapeutic target for sarcoma.

Immune checkpoint inhibitors in sarcomas: a systematic review

Sarcomas are tumors that originate from mesenchymal cells. The variety of sarcomas' response to chemotherapy and the wide range of prognosis reflect their heterogeneity. In order to improve the rates of response, the research has been orientated toward other forms of therapy, such as targeted therapies and immunotherapy or toward combinations of them. Immune checkpoint inhibitors (ICIs) have been the highlight of immunotherapy in the last decade. Although ICIs are already included in the guidelines of different malignancies, their clinical benefit in sarcomas is still under study. Alveolar soft part sarcomas, undifferentiated pleomorphic sarcomas and other subtypes of sarcoma with high presence of tertiary lymphoid structures tend to respond to ICIs, but further investigation is still needed. Furthermore, the search of predictive biomarkers to determine the type of sarcomas that are sensitive to ICIs is still very challenging. This review will focus on the results of clinical trials, which examine the effect of ICIs and their combination with chemotherapy, targeted therapies and other forms of immunotherapy in sarcomas.

Unlocking the potential of the tumor microenvironment for cancer therapy

The tumor microenvironment (TME) holds a crucial role in the progression of cancer. Epithelial-derived tumors share common traits in shaping the TME. The Warburg effect is a notable phenomenon wherein tumor cells exhibit resistance to apoptosis and an increased reliance on anaerobic glycolysis for energy production. Recognizing the pivotal role of the TME in controlling tumor growth and influencing responses to chemotherapy, researchers have focused on developing potential cancer treatment strategies. A wide array of therapies, including immunotherapies, antiangiogenic agents, interventions targeting cancer-associated fibroblasts (CAF), and therapies directed at the extracellular matrix, have been under investigation and have demonstrated efficacy. Additionally, innovative techniques such as tumor tissue explants, "tumor-on-a-chip" models, and multicellular tumor spheres have been explored in laboratory research. This comprehensive review aims to provide insights into the intricate cross-talk between cancer-associated signaling pathways and the TME in cancer progression, current therapeutic approaches targeting the TME, the immune landscape within solid tumors, the role of the viral TME, and cancer cell metabolism.

Molecular In-Depth Characterization of Chondrosarcoma for Current and Future Targeted Therapies

Chondrosarcoma (CHS) are heterogenous, but as a whole, represent the second most common primary malignant bone tumor entity. Although knowledge on tumor biology has grown exponentially during the past few decades, surgical resection remains the gold standard for the treatment of these tumors, while radiation and differentiated chemotherapy do not result in sufficient cancer control. An in-depth molecular characterization of CHS reveals significant differences compared to tumors of epithelial origin. Genetically, CHS are heterogenous, but there is no characteristic mutation defining CHS, and yet, IDH1 and IDH2 mutations are frequent. Hypovascularization, extracellular matrix composition of collagen, proteoglycans, and hyaluronan create a mechanical barrier for tumor suppressive immune cells. Comparatively low proliferation rates, MDR-1 expression and an acidic tumor microenvironment further limit therapeutic options in CHS. Future advances in CHS therapy depend on the further characterization of CHS, especially the tumor immune microenvironment, for improved and better targeted therapies.

The Next Frontier in Sarcoma: Molecular Pathways and Associated Targeted Therapies

Soft tissue sarcomas (STS) are a rare, complex, heterogeneous group of mesenchymal neoplasms with over 150 different histological subtypes. Treatments for this malignancy have been especially challenging due to the heterogeneity of the disease and the modest efficacy of conventional chemotherapy. The next frontier lies in discerning the molecular pathways in which these mesenchymal neoplasms arise, metastasize, and develop drug-resistance, thereby helping guide new therapeutic targets for the treatment of STS. This comprehensive review will discuss the current understanding of tumorigenesis of specific STS subtypes, including oncogenic pathway alterations involved in cell cycle regulation, angiogenesis, NOTCH signaling, and aberrant genetic rearrangements. It will then review current therapies that have been recently developed to target these pathways, including a review of ongoing clinical studies for targeted sarcoma treatment, as well as discuss new potential avenues for therapies against known molecular pathways of sarcomagenesis.

A 37-Year-Old Man with Myofibroblast Sarcoma Combined with Pleural Maculopathy: Case Report

Myofibroblastic sarcoma (MS) is a malignant tumor of soft tissue or bone that can occur in children or adults, with a high rate of recurrence and metastasis. We report a case of low-grade malignant MS of the left shoulder, diagnosed based on pathological examination and immunohistochemical staining. However, the patient had unexplained pleural maculopathy. The patient passed away 6 months after the diagnosis of myofibroblast sarcoma due to multiple metastases throughout the sarcoma. Combined with the patient's history, ancillary findings, and after MDT discussion, the patient was ultimately considered to have a high probability of myofibroblast sarcoma combined with pleural maculopathy. In conclusion, when a patient is diagnosed with myofibroblast sarcoma in combination with pleural macula, in the absence of other causative factors, a deep tissue biopsy of the pleura should be actively performed to confirm the diagnosis.

Expression and Clinical Significance of Various Checkpoint Molecules in Advanced Osteosarcoma: Possibilities for Novel Immunotherapy

OBJECTIVES

The fact that studies on anti-programmed cell death 1 (PD-1) or its relevant ligand 1 (PD-L1) have yielded such few responses greatly decreases the confidence in immunotherapy with checkpoint inhibitors for advanced osteosarcoma. We intended to characterize the expression of various checkpoint molecules with immunohistochemistry in osteosarcoma specimens and analyzed the relationship of the expression of these checkpoint molecules with patients' clinical courses.

METHODS

This study was a retrospective non-intervention study from August 1st 2017 to March 1st 2020. Immunohistochemistry for B7-H3 (CD276, Cluster of Differentiation 276), CD47 (Cluster of Differentiation 47), PD-L1 (programmed cell death ligand 1), TIM3 (mucin-domain containing-3), TGF-β (TransformingGrowth Factor β), CXCR 4 (Chemokine Receptor 4), CD27 (Cluster of Differentiation 27), IDO1 (Indoleamine 2,3-dioxygenase 1), KIRs (Killer cell Immunoglobulin-like Receptors), and SDF-1 (Stromal cell-Derived Factor-1) was performed on 35 resected osteosarcoma specimens. Patients progressed upon first-line chemotherapy with evaluable lesions were qualified for this study, and their specimens previously stored in the pathological department repository would be retrieved for analysis. Associations between the immunohischemistry markers and clinicopathological variables and survival were evaluated by the χ² displayed by cross-table, Cox proportional hazards regression model, and Kaplan-Meier plots.

RESULTS

The positive rates of B7-H3, CD47, PD-L1, TIM3, and TGF-β expression in this sample of 35 heavily treated osteosarcomas were 29% (10/35), 15% (5/35), 9% (3/35), 6% (2/35), and 6% (2/35), respectively, and diverse staining intensities were observed. Among these advanced patients, 15/35 (43%) had positive checkpoint expression, of which 33% (5/15) showed evidence of the co-expression of more than one checkpoint molecule. We did not find any obvious correlation with clinicopathological characteristics and the positive expression of these molecules.

CONCLUSIONS

The present study highlights that only a small subset of progressive osteosarcomas, which had been heavily-treated, expressed tumor immune-associated checkpoint molecules, of which B7-H3 was the most positively expressed checkpoint and might be a promising target for further osteosarcoma investigation.

Primary peritoneal hemangioendothelioma simulating an ovarian cyst: A case report and review of literature

BACKGROUND

Epithelioid hemangioendothelioma (EHE) is an extremely rare tumor with a prevalence of one in a million and a very heterogenous spectrum of disease that varies from an indolent to a metastasizing aggressive disease, with the liver, lung and bone being the primarily involved organs. Peritoneal forms of EHE are even rare, and only 12 cases have been reported to date in the literature.

CASE SUMMARY

A 66-year-old female came to our attention complaining low abdominal and perineal pain. Magnetic resonance imaging examination showed a 52 mm × 58 mm × 32 mm cystic mass with some smooth septa, simulating an ovarian cyst. Explorative laparoscopy demonstrated the presence of a peritoneal mass of augmented consistency connected with a sigmoid epiploic appendix in the right side of the Pouch of Douglas, that was surgically removed. Histological exa-mination revealed a primitive peritoneafl hemangioendothelioma. The patient easily recovered from surgery with no residual pain or discomfort. She is regularly attending a 3-years follow-up that is negative for local recurrence of disease or distant metastases.

CONCLUSION

Peritoneal form of EHE often simulates masses of other nature, as in our case. Given its unspecific clinical and radiological presentation, patients are often forced to a large series of tests and examinations before reaching a definitive diagnosis, that can only histologically made. The possibility of EHE should always be considered in case of unexplained chronic abdominal pain associated to a non-specific mass.

Molecular and clinicopathological analysis revealed an immuno-checkpoint inhibitor as a potential therapeutic target in a subset of high-grade myxofibrosarcoma

This study aimed to identify differences in genetic alterations between low- and high-grade lesions in myxofibrosarcoma (MFS) and to examine the efficacy of immune checkpoint inhibitors in 45 patients with MFS. First, genetic differences between low- and high-grade components within the same tumor were analyzed in 11 cases using next-generation sequencing. Based on the obtained data, Sanger sequencing was performed for TP53 mutations in the remaining 34 patients. Loss of heterozygosity (LOH) analysis was performed at the TP53 and RB1 loci. Immunohistochemistry was performed for FGFR3, KIT, MET, programmed death receptor ligand 1 (PD-L1), CD8, FOXP3, and mismatch repair proteins. The microsatellite instability status was also evaluated in all cases. TP53 deleterious mutations and LOH at TP53 and RB1 loci were detected significantly more frequently in high-grade than in low-grade MFS (P = 0.0423, 0.0455, and 0.0455, respectively). LOH at the RB1 locus was significantly associated with shorter recurrence-free survival in both univariate and multivariate analyses. TP53 alterations, such as mutation and LOH, were more frequently observed in low-grade areas within high-grade MFS than in pure low-grade MFS. The positive PD-L1 expression rate was 35.6% (16/45), and all these 16 cases were high-grade. A high density of both CD8+ and FOXP3+ tumor-infiltrating lymphocytes was associated with PD-L1 positivity. LOH at the RB1 locus was identified an independent adverse prognostic factor for recurrence-free survival in patients with MFS. Immune checkpoint inhibitors may be a therapeutic option for a subset of high-grade MFS.

Prognostic significance and therapeutic potentials of immune checkpoints in osteosarcoma

Although there exist manifold strategies for cancer treatment, researchers are obliged to develop novel treatments based on the challenges that arise. One of these recent treatment approaches is cancer immunotherapy, which enjoys various types of strategies itself. However, one of the most significant methods, in this regard, is employing immune checkpoint proteins (ICPs). Bone sarcomas have several subtypes, with the most common ones being chordoma, chondrosarcoma, Ewing sarcoma, and osteosarcoma. Although many aggressive treatment approaches, including radiotherapy, chemotherapy, and surgical resection, have been employed over the last decades, significantly improved outcomes have not been observed for Ewing sarcoma or osteosarcoma patients. Additionally, chordoma and chdrosarcoma resist against both radiation and chemotherapy. Accordingly, elucidating how recent therapies could affect bone sarcomas is necessary. Checkpoint inhibitors have attracted great attention for the treatment of several cancer types, including bone sarcoma. Herein, the recent advances of current immune checkpoint targets, such as anti-PD-1/PD-L1 and anti-CTLA-4 blockade, for the treatment of bone sarcoma have been reviewed.

Evaluation of PD-L1 Expression in Undifferentiated Pleomorphic Sarcomas, Liposarcomas and Chondrosarcomas

Immune checkpoint inhibitors (ICIs) such as PD1/PD-L1 blockers are an established treatment for many solid cancers. There are currently no approved ICIs for sarcomas, but satisfactory results have been seen in some patients with disseminated disease in certain histological types. Most studies on PD-L1 in sarcoma have used small specimens and there are no clear cutoff values for scoring. We investigated PD-L1 immunoreactivity in high-grade chondrosarcomas (CS), abdominal liposarcoma (LS) and undifferentiated pleomorphic sarcomas (UPS). In total, 230 tumors were stained with SP142 and SP263 assays and evaluated by two clinical pathologists. Immunoreactivity in tumor and immune cells was correlated with clinical outcome. Overall, ≥1% PD-L1 immunoreactivity in tumor cells was found in 11 CS, 26 LS and 59 UPS (SP142 assay) and in 10 CS, 26 LS and 77 UPS (SP263 assay). Most tumors exhibited ≤10% PD-L1 immunoreactivity, but a subset across all three subtypes had >50%. Kaplan-Meier survival analysis showed no significant difference in metastasis-free or overall survival in relation to PD-L1 immunoreactivity in tumor or immune cells for any subtype. As there is a lack of clinical data regarding PD-L1/PD-1 status and therapy response, it is not currently possible to establish clear cutoff values. Patients with high (>50%) PD-L1 immunoreactivity in tumor cells (TC) with the SP263 assay would be a logical group to investigate for potentially beneficial PD1/PD-L1-targeted treatment.

Improving Immunotherapy Efficacy in Soft-Tissue Sarcomas: A Biomarker Driven and Histotype Tailored Review

Anti-PD-(L)1 therapies yield a disappointing response rate of 15% across soft-tissue sarcomas, even if some subtypes benefit more than others. The proportions of TAMs and TILs in their tumor microenvironment are variable, and this heterogeneity correlates to histotype. Tumors with a richer CD8+ T cell, M1 macrophage, and CD20+ cells infiltrate have a better prognosis than those infiltrated by M0/M2 macrophages and a high immune checkpoint protein expression. PD-L1 and CD8+ infiltrate seem correlated to response to immune checkpoint inhibitors (ICI), but tertiary lymphoid structures have the best predictive value and have been validated prospectively. Trials for combination therapies are ongoing and focus on the association of ICI with chemotherapy, achieving encouraging results especially with pembrolizumab and doxorubicin at an early stage, or ICI with antiangiogenics. A synergy with oncolytic viruses is seen and intratumoral talimogene laherpavec yields an impressive 35% ORR when associated to pembrolizumab. Adoptive cellular therapies are also of great interest in tumors with a high expression of cancer-testis antigens (CTA), such as synovial sarcomas or myxoid round cell liposarcomas with an ORR ranging from 20 to 50%. It seems crucial to adapt the design of clinical trials to histology. Leiomyosarcomas are characterized by complex genomics but are poorly infiltrated by immune cells and do not benefit from ICI. They should be tested with PIK3CA/AKT inhibition, IDO blockade, or treatments aiming at increasing antigenicity (radiotherapy, PARP inhibitors). DDLPS are more infiltrated and have higher PD-L1 expression, but responses to ICI remain variable across clinical studies. Combinations with MDM2 antagonists or CDK4/6 inhibitors may improve responses for DDLPS. UPS harbor the highest copy number alterations (CNA) and mutation rates, with a rich immune infiltrate containing TLS. They have a promising 15-40% ORR to ICI. Trials for ICB should focus on immune-high UPS. Association of ICI with FGFR inhibitors warrants further exploration in the immune-low group of UPS. Finally translocation-related sarcomas are heterogeneous, and although synovial sarcomas a poorly infiltrated and have a poor response rate to ICI, ASPS largely benefit from ICB monotherapy or its association with antiangiogenics agents. Targeting specific neoantigens through vaccine or adoptive cellular therapies is probably the most promising approach in synovial sarcomas.

Clinical biomarkers in soft tissue sarcoma A comprehensive review of current soft tissue sarcoma biomarkers

Soft tissue sarcomas (STS) are a heterogeneous group of tumors that arise from mesenchymal tissue. Investigation at the molecular level has been challenging due to the rarity of STS and the number of histologic subtypes. However, recent research has provided new insight into potential genomic, proteomic, and immunological biomarkers of STS. The identification of biomarkers can improve diagnosis, prognosis, and prediction of recurrence and treatment response. This review provides an understanding of biomarkers, discussing the current status of biomarker research in STS.

Is immunotherapy in the future of therapeutic management of sarcomas?

Sarcomas are rare, ubiquitous and heterogeneous tumors usually treated with surgery, chemotherapy, target therapy, and radiotherapy. However, 25-50% of patients experience local relapses and/or distant metastases after chemotherapy with an overall survival about 12-18 months. Recently, immuno-therapy has revolutionized the cancer treatments with initial indications for non-small cell lung cancer (NSCLC) and melanoma (immune-checkpoint inhibitors).Here, we provide a narrative review on the topic as well as a critical description of the currently available trials on immunotherapy treatments in patients with sarcoma. Given the promising results obtained with anti-PD-1 monoclonal antibodies (pembrolizumab and nivolumab) and CAR-T cells, we strongly believe that these new immunotherapeutic approaches, along with an innovative characterization of tumor genetics, will provide an exciting opportunity to ameliorate the therapeutic management of sarcomas.

Immunotherapy for sarcomas

Sarcomas are a heterogeneous group of malignancies of mesenchymal origin; their molecular and genomic mechanisms differ with regard to histology. These characteristics lead to the presentation of varied immunological profiles based on the tumor microenvironment. Various immunotherapies are considered for the treatment of sarcoma. These treatments are performed either in isolation or in combination with other methods such as cytotoxic chemotherapy or the use of molecular target agents. Among these, two recently emerging immunotherapies include T-cell receptor gene therapy and immune checkpoint inhibitor therapy, which are expected to be effective for many types of sarcoma. A sarcoma with a disease-specific translocation and a limited number of mutations, such as synovial sarcoma, expresses high levels of self-antigens, like the New York esophageal squamous cell carcinoma 1, which has been targeted in T-cell receptor gene therapy. On the other hand, sarcomas with a greater number of mutations, such as undifferentiated pleomorphic sarcomas, myxofibrosarcoma and dedifferentiated liposarcomas, can be good candidates for immune checkpoint inhibitors. Among immune checkpoint inhibitor therapies, programmed cell death-1 blockade (nivolumab and pembrolizumab) and cytotoxic T-lymphocyte-associated antigen 4 blockade (ipilimumab) have been investigated most often in sarcoma. Although the sole use of immune checkpoint inhibitors provides limited efficacy, combined immunotherapy with immune checkpoint inhibitors or molecular target agents, especially antiangiogenic agents, has shown moderate results against some types of sarcoma, such as the alveolar soft part sarcoma. Several clinical trials utilizing immunotherapy, including T-cell receptor gene therapy and immune checkpoint inhibitors, in sarcomas are under progress. By clarifying the tumor microenvironment and biomarker-predictive capacity of immunotherapy in sarcomas, better clinical trials can be designed; this could lead to improved outcomes for immunotherapy in sarcoma.

Real-world experience with pembrolizumab in patients with advanced soft tissue sarcoma

Background

The goal of this study was to retrospectively analyze the efficacy and safety of pembrolizumab in the real-world treatment of soft tissue sarcoma (STS).

Methods

We analyzed 38 patients who suffered from STS and received pembrolizumab treatment from July 2017 to December 2018 in our hospital. We investigated the influence of clinical characteristics, treatment timing, and treatment protocol on objective response rate (ORR). We also investigated the factors affecting overall survival (OS) and progression-free survival (PFS), as well as the occurrence of severe adverse events (SAEs).

Results

The overall ORR was 19.4% (7/36). The ORRs of patients who received pembrolizumab treatment as first-line, second-line, and third-line therapy were 42.9% (3/7), 25.0% (4/16), and 0% (0/13), respectively, which showed marginal significance (P=0.052). Four patients (11.1%) maintained a complete response (CR) or partial response (PR) for at least 6 months with pembrolizumab monotherapy, or after withdrawal of chemotherapy or targeted therapy regimens. The median PFS was 2.9 months [95% confidence interval (CI): 2.4–3.4 months] and the median OS was 12.0 months (95% CI: 10.2–13.8 months). Cox regression analysis showed that treatment time was an independent factor affecting PFS (P=0.041), while Eastern Cooperative Oncology Group (ECOG) performance status (PS) score was the only independent factor affecting OS (P=0.028).

Conclusions

In the real world, the effectiveness of pembrolizumab in the treatment of STS was low. Some subtypes showed a limited response to pembrolizumab, including alveolar soft part sarcoma (ASPS), undifferentiated pleomorphic sarcoma (UPS), exoskeletal chondrosarcoma (ESCS), and angiosarcoma (AS), while the response in leiomyosarcoma (LMS) was low. Combination therapy may increase the risk of SAEs, especially when combined with pazopanib.

A Review of the Spectrum of Imaging Manifestations of Epithelioid Hemangioendothelioma

OBJECTIVE. The purpose of this article is to review the spectrum of imaging manifestations of epithelioid hemangioendothelioma across different organ systems and briefly describe its current treatment strategies. CONCLUSION. Epithelioid hemangioendothelioma is a rare, locally invasive neoplasm with metastatic potential. Although most commonly occurring in liver, lungs, and bones, it can also present at multiple other sites. Because of its nonspecific clinical and imaging manifestations, it is often misdiagnosed. The possibility of epithelioid hemangioendothelioma must be considered in the presence of a slowly growing mass that invades adjacent structures. Imaging can help plan percutaneous biopsy, detect sites of disease, and identify poor prognostic factors.

Activity of PD1 inhibitor therapy in advanced sarcoma: a single-center retrospective analysis

BACKGROUND

Sarcomas constitute a heterogeneous group of tumors with different clinical behaviors and variable responses to systemic therapies. Recent immunotherapy studies with PD1 inhibitors (PD1i) show promising results with use in certain soft-tissue sarcomas; however, the clinical and molecular features that best predict response to PD1i remain unclear.

METHODS

Demographic, imaging, histologic, and genetic sequencing data was collected for sarcoma patients who received nivolumab or pembrolizumab (PD1i) treatment at our institution between January 1st 2015 and April 23rd 2018. The primary objective was to determine progression-free survival (PFS) in patients with advanced sarcomas receiving PD1i. Secondary objectives included determining overall survival (OS) and assessment of characteristics associated with response to PD1i. Fifty-six patients who were treated with PD1i therapy met inclusion criteria for this study.

RESULTS

Partial response towards PD1i treatment was seen in 3 in 26 evaluable patients, but no complete responses were observed (overall response rate 11.5%). Within this group of patients, the 90 day PFS was found to be 48.8%. In patients in whom PD1 expression was known, there was a statistically significant positive correlation between expression of PD1 and longer PFS and OS rates. Patients that were treated with more than four cycles of PD1i therapy were also more likely to have a greater OS.

CONCLUSIONS

This study suggests activity of PD1i in a pretreated cohort of advanced sarcoma patients, particularly for the subset of patients with PD1 positive tumors. Our results highlight the importance of further research to better target the optimal patient population and markers of response.

Prevalence of PD-L1 expression in matched recurrent and/or metastatic sarcoma samples and in a range of selected sarcomas subtypes

We assessed the frequency of programmed death-ligand 1 (PD-L1) expression by immunohistochemistry (IHC) in a cohort of 522 sarcomas from 457 patients, incuding a subset of 46 patients with 63 matched samples from local recurrence or metastases with primary tumours and/or metachronous metastases. We also investigated the correlation of PD-L1 with the presence and degree of tumour-infiltrating lymphocytes (TILs) in a subset of cases. IHC was performed using the PD-L1 SP263 companion kit (VENTANA) on tissue microarrays from an archival cohort. Evaluation of PD-L1 and TILs was performed on full sections for a subset of 23 cases. Fisher’s exact and Mann Whitney test were used to establish significance (P <0.05). PD-L1 positive expression (≥1%) was identified in 31% of undifferentiated pleomorphic sarcomas, 29% of angiosarcomas, 26% of rhabdomyosarcomas, 18% of myxofibrosarcomas, 11% of leiomyosarcomas and 10% of dedifferentiated liposarcomas. Negative expression was present in all atypical lipomatous tumous/well-differentiated lipoasarcomas, myxoid liposarcomas, synovial sarcomas, pleomorphic liposarcomas, and Ewing sarcomas. PD-L1 IHC was concordant in 81% (38 of 47) of matched/paired samples. PD-L1 IHC was discordant in 19% (9 of 47 matched/paired samples), displaying differences in the proportion of cells expressing PD-L1 amongst paired samples with the percentage of PD-L1-positive cells increasing in the metastatic/recurrent site compared to the primary in 6 of 9 cases (67%). Significant correlation between PD-L1 expression and the degree of TILs was exclusively identified in the general cohort of leiomyosarcomas, but not in other sarcoma subtypes or in metastatic/recurrent samples. We conclude that the prevalence of PD-L1 expression in selected sarcomas is variable and likely to be clone dependent. Importantly, we demonstrated that PD-L1 can objectively increase in a small proportion of metastases/recurrent sarcomas, offering the potential of treatment benefit to immune checkpoint inhibitors in this metastatic setting.

Immunotherapy of heterogenous sarcomas: questions and strategies

PURPOSE OF REVIEW

Development of immune therapy in sarcoma faces the rarity and heterogeneity of the disease. This review analyses the data available from published clinical trials, and the new clinical strategies under assessment, developed in parallel to the exploration of biological mechanisms underlying the efficacy of immune therapy.

RECENT FINDINGS

Published data of four clinical trials assessing the efficacy of immune therapy in metastatic bone and soft-tissue sarcoma and associated translational programs are available. Response rate and progression-free survival with single-agent immune check point blockade in unselected sarcoma are low. No biomarkers of efficacy have been identified so far. To increase the efficacy of such treatments, combination of immune check point blockade with chemotherapy, radiotherapy or targeted therapy is currently assessed. Signal of specific sensibility of some histological subtypes is explored. Adoptive cell therapy or vaccine seems particularly promising in translocation-associated sarcoma.

SUMMARY

Characterization of immune environment, mechanism of action of combined regimen and identification of biomarkers will be key steps to build the next clinical trials to improve the efficacy of such strategy.

Lactate in Sarcoma Microenvironment: Much More than just a Waste Product

Sarcomas are rare and heterogeneous malignant tumors relatively resistant to radio- and chemotherapy. Sarcoma progression is deeply dependent on environmental conditions that sustain both cancer growth and invasive abilities. Sarcoma microenvironment is composed of different stromal cell types and extracellular proteins. In this context, cancer cells may cooperate or compete with stromal cells for metabolic nutrients to sustain their survival and to adapt to environmental changes. The strict interplay between stromal and sarcoma cells deeply affects the extracellular metabolic milieu, thus altering the behavior of both cancer cells and other non-tumor cells, including immune cells. Cancer cells are typically dependent on glucose fermentation for growth and lactate is one of the most heavily increased metabolites in the tumor bulk. Currently, lactate is no longer considered a waste product of the Warburg metabolism, but novel signaling molecules able to regulate the behavior of tumor cells, tumor-stroma interactions and the immune response. In this review, we illustrate the role of lactate in the strong acidity microenvironment of sarcoma. Really, in the biological context of sarcoma, where novel targeted therapies are needed to improve patient outcomes in combination with current therapies or as an alternative treatment, lactate targeting could be a promising approach to future clinical trials.

Driving innovation for rare skin cancers: utilizing common tumours and machine learning to predict immune checkpoint inhibitor response

Metastatic Merkel cell carcinoma (MCC) and cutaneous squamous cell carcinoma (cSCC) are rare and both show impressive responses to immune checkpoint inhibitor treatment. However, at least 40% of patients do not respond to these expensive and potentially toxic drugs. Development of predictive biomarkers of response and rational, effective combination treatment strategies in these rare, often frail patient populations is challenging. This review discusses the pathophysiology and treatment of MCC and cSCC, with a particular focus on potential biomarkers of response to immunotherapy, and discusses how transfer learning using big data collected from patients with common tumours can be used in combination with deep phenotyping of rare tumours to develop predictive biomarkers and elucidate novel treatment targets.

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Metastatic Merkel cell carcinoma and cutaneous squamous cell carcinoma are rare tumours.

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Immunotherapy gives impressive responses but most patients do not survive long term.

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Small patient numbers prevent extensive biomarker research in clinical trials.

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Pooled data from common and rare tumours can be used to train neural networks.

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In rare cancers, neural networks can help identify biomarkers and novel treatment targets.

Surgical Outcomes and Risk Analysis of Primary Pulmonary Sarcoma

BACKGROUND

Primary pulmonary sarcoma (PPS) is a rare malignant lung neoplasm, and there is very little medical evidence about treatment of PPS. The aim of this study is to clarify the clinical characteristics and therapeutic outcome of patients who underwent surgical resection for PPS.

METHODS

We retrospectively reviewed the records of patients who underwent surgical resection for PPS in our institution between 1995 and 2014. Cases who only underwent biopsy were excluded.

RESULTS

A total of 24 patients (18 males, 6 females), with a median age of 60 (interquartile range: 44-67) years, were analyzed. The surgical procedures performed in these patients were pneumonectomy (n = 10), lobectomy (n = 11), and wedge resection (n = 3). Complete resection was achieved in 16 patients. The pathological stages (tumor, node, metastases lung cancer classification, 8th edition) of the patients were I (n = 4), II (n = 12), III (n = 2), and IV (n = 5), and there were four cases of lymph node metastasis. The 5-year overall survival rate of the patients was 50% (95% confidence interval [CI]: 29-72). Adverse prognostic factors for overall survival were incomplete resection (hazard ratio [HR]: 4.4, 95% CI: 2.1-42), advanced pathological stage (HR 14, 95% CI: 2.8-66), higher pathological grade (HR 4.5, 95% CI: 1.2-17), and tumor size ≥ 7 cm (HR 4.7, 95% CI: 1.1-21).

CONCLUSIONS

Our series of PPS revealed that incomplete resection, advanced pathological stage, higher pathological grade, and tumor size were unfavorable factors for long-term survival.

PD-1 Inhibition Achieves a Complete Metabolic Response in a Patient with Malignant Peripheral Nerve Sheath Tumor

High-grade malignant peripheral nerve sheath tumors (MPNST) have a poor prognosis with limited responsiveness to systemic therapy. We document a case of a complete metabolic response to pembrolizumab monotherapy in metastatic disease. Tumor molecular profiling identified programmed-death ligand-1 (PD-L1) positivity. This characteristic provided a rationale for immune-checkpoint therapy. Treatment with pembrolizumab resulted in a complete metabolic response after four cycles of therapy. Patients with PD-L1-positive, metastatic MPNST may be candidates for immune-checkpoint therapy, which may produce a durable complete remission. Future study of anti-PD-1/PD-L1 therapy is warranted.

Genetic variants and copy number changes in soft tissue leiomyosarcoma detected by targeted amplicon sequencing

Aims

Leiomyosarcomas (LMSs) occur in various tissues and harbour potential for metastases. The genomic landscape of LMS is poorly understood. In an effort to improve understanding of the LMS genome, we analysed 11 LMSs of somatic soft tissue including matching tissue of normal phenotype.

Methods

DNA derived from microdissected tumour domains and matching normal tissue underwent amplicon sequencing of 409 tumour suppressors and oncogenes using the Ion Torrent Comprehensive Cancer Panel.

Results

Genomic changes were heterogeneous with few recurrent abnormalities detected. Coding variants were identified in genes involved in signal transduction, transcriptional regulation and DNA repair. There were variants in several genes related to angiogenesis and GPR124 variants (TEM5) were confirmed by immunohistochemical analysis of a LMS tissue microarray. Surprisingly, there were shared coding variants in tumour and corresponding normal tissue.

Conclusions

LMSs are a very heterogeneous population lacking recurrent somatic abnormalities. The presence of damaging mutations in normal tissue may reflect either a germline predisposition or field effect rather than tissue contamination. Hopeful therapeutic targets appear to be those related to AKT/MTOR pathway.

MSIpred: a python package for tumor microsatellite instability classification from tumor mutation annotation data using a support vector machine

Microsatellite instability (MSI) is characterized by high degree of polymorphism in microsatellite lengths due to deficiency in mismatch repair (MMR) system. MSI is associated with several tumor types and its status can be considered as an important indicator for patient prognosis. Conventional clinical diagnosis of MSI examines PCR products of a panel of microsatellite markers using electrophoresis (MSI-PCR), which is laborious, costly, and time consuming. We developed MSIpred, a python package for automatic MSI classification using a machine learning technology – support vector machine (SVM). MSIpred computes 22 features characterizing tumor somatic mutational load from mutation data in mutation annotation format (MAF) generated from paired tumor-normal exome sequencing data, subsequently using these features to predict tumor MSI status with a SVM classifier trained by MAF data of 1074 tumors belonging to four types. Evaluation of MSIpred on an independent testing set, MAF data of another 358 tumors, achieved overall accuracy of ≥98% and area under receiver operating characteristic (ROC) curve of 0.967. Further analysis on discrepant cases revealed that discrepancies were partially due to misclassification of MSI-PCR. Additional testing of MSIpred on non-TCGA data also validated its good classification performance. These results indicated that MSIpred is a robust pan-tumor MSI classification tool and can serve as a complementary diagnostic to MSI-PCR in MSI diagnosis.

MMP-9 as a Candidate Marker of Response to BRAF Inhibitors in Melanoma Patients With BRAFV600E Mutation Detected in Circulating-Free DNA

The BRAF^V600E mutation is associated with melanoma development and its detection in circulating-free DNA cannot be observed in all melanoma patients harboring this mutation in tumor specimens. Beside the circulating-free DNA BRAF^V600E mutation, other markers of therapeutic response should be identified. Matrix metalloproteinase-9 (MMP-9) could be one of them as its role as indicator of invasiveness in melanoma have been explored. In this study, MMP-9 was evaluated in melanoma cells after treatment with dabrafenib. In vitro data were validated in 26 melanoma patients, of which 14 treated with BRAF inhibitor alone and 12 treated with both BRAF and MEK inhibitors, by ELISA assay and droplet digital PCR for measuring MMP-9 serum levels and circulating-free DNA BRAF^V600E mutation, respectively. Statistical analyses were performed to evaluate the prognostic significance of MMP-9, progression-free survival (PFS) and overall survival (OS) according to the BRAF^V600E mutation and MMP-9 levels. The performed analyses showed that MMP-9 and pEKR1-2 were statistically down-regulated in melanoma cells after treatment with dabrafenib. Circulating-free DNA BRAF^V600E mutation was detected in 11 out of 26 melanoma patients showing higher levels of MMP-9 compared to those with undetectable BRAF^V600E mutation. Furthermore, higher levels of MMP-9 and circulating-free DNA BRAF^V600E mutation were associated with lower PFS and OS. Finally, the monitoring of therapy showed that MMP-9 significantly decreased at T1 and T2, but not at T-last, for the patients with detectable circulating-free DNA BRAF^V600E mutation. In conclusion, high levels of MMP-9 and circulating-free DNA BRAF^V600E mutation are associated with poor PFS and OS. MMP-9 may represent a promising indicator of response to BRAF inhibitors in combination with the detection of BRAF^V600E mutation.