The prognostic value of tumor-associated macrophages in leiomyosarcoma: a single institution study

Immunotherapy and Radiotherapy Combinations for Sarcoma

Sarcomas are a heterogeneous group of bone and soft tissue tumors. Survival outcomes for advanced (unresectable or metastatic) disease remain poor, so therapeutic improvements are needed. Radiotherapy plays an integral role in the neoadjuvant and adjuvant treatment of localized disease as well as in the treatment of metastatic disease. Combining radiotherapy with immunotherapy to potentiate immunotherapy has been used in a variety of cancers other than sarcoma, and there is opportunity to further investigate combining immunotherapy with radiotherapy to try to improve outcomes in sarcoma. In this review, we describe the diversity of the tumor immune microenvironments for sarcomas and describe the immunomodulatory effects of radiotherapy. We discuss studies on the timing of radiotherapy relative to immunotherapy and studies on the radiotherapy dose and fractionation regimen to be used in combination with immunotherapy. We describe the impact of radiotherapy on the tumor immune microenvironment. We review completed and ongoing clinical trials combining radiotherapy with immunotherapy for sarcoma and propose future directions for studies combining immunotherapy with radiotherapy in the treatment of sarcoma.

Predictive Biomarkers of Pathological Response to Neoadjuvant Chemoradiotherapy for Locally Advanced Soft Tissue Sarcomas

BACKGROUND

Marginally resectable and unresectable soft tissue sarcomas (STS) remain a therapy challenge due to the lack of highly active treatment. The aim of the study was to identify a biomarker to predict the pathological response (PR) to preplanned treatment of these STSs.

METHODS

In the phase II clinical trial (NCT03651375), locally advanced STS patients received preoperative treatment with a combination of doxorubicin-ifosfamide chemotherapy and 5 × 5 Gy radiotherapy. PR to the treatment was classified using the European Organization for Research and Treatment of Cancer-Soft Tissue and Bone Sarcoma Group recommendations. We have chosen HIF-1α, CD163, CD68, CD34, CD105, and γH2AFX proteins, rendering different biological phenomena, for biomarker study.

RESULTS

Nineteen patients were enrolled and in four cases a good PR was reported. The high expression of HIF-1α before surgery showed a negative correlation with PR, which means a poor response to therapy. Furthermore, the samples after surgery had decreased expression of HIF-1α, which confirmed the correlation with PR. However, high expression of γH2AFX positively correlated with PR, which provides better PR. The high number of positive-staining TAMs and the high IMVD did not correlate with PR.

CONCLUSIONS

HIF1α and γH2AFX could be potential biomarkers for PR prediction after neoadjuvant treatment in STS.

Therapeutic advances in leiomyosarcoma

Leiomyosarcoma is an aggressive mesenchymal malignancy and represents one of the most common subtypes of soft tissue sarcomas. It is characterized by significant disease heterogeneity with variable sites of origin and diverse genomic profiles. As a result, the treatment of advanced leiomyosarcoma is challenging. First-line therapy for metastatic and/or unresectable leiomyosarcoma includes anthracycline or gemcitabine based regimens, which provide a median progression-free survival time of about 5 months and overall survival time between 14-16 months. Effective later-line therapies are limited. Molecular profiling has enhanced our knowledge of the pathophysiology driving leiomyosarcoma, providing potential targets for treatment. In this review, we explore recent advances in our understanding of leiomyosarcoma tumor biology and implications for novel therapeutics. We describe the development of clinical trials based on such findings and discuss available published results. To date, the most promising approaches for advanced leiomyosarcoma include targeting DNA damage repair pathways and aberrant metabolism associated with oncogenesis, as well as novel chemotherapy combinations. This review highlights the recent progress made in the treatment of advanced leiomyosarcoma. Ongoing progress is contingent upon further development of clinical trials based on molecular findings, with careful consideration for clinical trial design, strong academic collaborations, and prospective correlative analyses.

Systemic Inflammatory Indices in Second-Line Soft Tissue Sarcoma Patients: Focus on Lymphocyte/Monocyte Ratio and Trabectedin

A second-line standard of treatment has not yet been identified in patients with soft tissue sarcomas (STS), so identifying predictive markers could be a valuable tool. Recent studies have shown that the intratumoral and inflammatory systems significantly influence tumor aggressiveness. We aimed to investigate prognostic values of pre-therapy neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), lymphocyte-to-monocyte ratio (LMR), systemic inflammatory index (SII), progression-free survival (PFS), and overall survival (OS) of STS patients receiving second-line treatment. In this single-center retrospective analysis, ninety-nine patients with STS were enrolled. All patients received second-line treatment after progressing to anthracycline. PFS and OS curves were calculated using the Kaplan-Meier method of RNA sequencing, and CIBERSORT analysis was performed on six surgical specimens of liposarcoma patients. A high NLR, PLR, and SII were significantly associated with worse PFS (p = 0.019; p = 0.004; p = 0.006). Low LMR was significantly associated with worse OS (p = 0.006). Patients treated with Trabectedin showed a better PFS when the LMR was low, while patients treated with other regimens showed a worse PFS when the LMR was low (p = 0.0154). The intratumoral immune infiltrates analysis seems to show a correlation between intratumoral macrophages and LMR. PS ECOG. The metastatic onset and tumor burden showed prognostic significance for PFS (p = 0.004; p = 0.041; p = 0.0086). According to the histologies, PFS was: 5.7 mo in liposarcoma patients vs. 3.8 mo in leiomyosarcoma patients vs. 3.1 months in patients with other histologies (p = 0.053). Our results confirm the prognostic role of systemic inflammatory markers in patients with STS. Moreover, we demonstrated that LMR is a specific predictor of Trabectedin efficacy and could be useful in daily clinical practice. We also highlighted a possible correlation between LMR levels and the percentage of intratumoral macrophages.

Macrophage numbers in the marginal area of sarcomas predict clinical prognosis

Even when treated comprehensively by surgery, chemotherapy, and radiotherapy, soft-tissue sarcoma has an unfavorable outcome. Because soft-tissue sarcoma is rare, it is the subject of fewer clinicopathological studies, which are important for clarifying pathophysiology. Here, we examined tumor-associated macrophages in the intratumoral and marginal areas of sarcomas to increase our knowledge about the pathophysiology. Seventy-five sarcoma specimens (not limited to a single histological type), resected at our institution, were collected, and the number of CD68-, CD163-, and CD204-positive macrophages in the intratumoral and marginal areas was counted. We then performed statistical analysis to examine links between macrophage numbers, clinical factors, and outcomes. A high number of macrophages positive for all markers in both areas was associated with worse disease-free survival (DFS). Next, we divided cases according to the FNCLCC classification (Grade 1 and Grades 2/3). In the Grade 1 group, there was no significant association between macrophage number and DFS. However, in the Grade 2/3 group, high numbers of CD163- and CD204-positive macrophages in the marginal area were associated with poor DFS. By contrast, there was no significant difference between the groups with respect to high or low numbers of CD68-, CD163-, or CD204-positive macrophages in the intratumoral area. Multivariate analysis identified the number of CD163- and CD204-positive macrophages in the marginal area as an independent prognostic factor. Macrophage numbers in the marginal area of soft-tissue sarcoma may better reflect clinical behavior.

Immune-cell infiltration in high-grade soft tissue sarcomas; prognostic implications of tumor-associated macrophages and B-cells

BACKGROUND

Soft tissue sarcomas are rare, morphologically, and genetically heterogenous. Though the tumors display abundant tumor stroma with infiltrating immune cells, the prognostic impact of various immunologic markers in sarcoma remains poorly defined. We aimed to characterize the immune landscape of a treatment-naïve cohort of soft tissue sarcoma of the extremities and the trunk wall with correlations to metastasis-free survival.

MATERIALS AND METHODS

We surveyed immunohistochemical expression patterns for CD163, CD20, CD3, CD8, and FOXP3 in 134 adult high-grade leiomyosarcomas, liposarcomas, and synovial sarcomas.

RESULTS

Macrophages outnumbered tumor-infiltrating lymphocytes. High CD163 infiltration was identified in 49% of the tumors and was overrepresented (66%) in leiomyosarcoma compared to liposarcoma (46%) and synovial sarcoma (9%). Tumor-grade also correlated with CD163 positivity with high expression in 53% of the high-grade lesions and 28% in low-grade tumors. Infiltrating CD3, CD8 and FOXP3-positive T-cells were significantly more prevalent in leiomyosarcomas than in liposarcomas/synovial sarcomas. CD20⁺ B-cells were identified only in 14% of the STS. Correlation to established prognostic factors revealed a correlation between CD163⁺ macrophages and necrosis and predicted an increased risk of metastases. No correlation between CD20⁺ B-cells and known prognostic factors could be established, though CD20⁺ B-cells infiltration predicted improved overall survival.

CONCLUSION

We confirm that tumor-infiltrating macrophages outnumber tumor-infiltrating lymphocytes in soft tissue sarcoma and signify an increased risk of metastasis. CD20⁺ B-cells are scarce in STS and correlate to improved survival. To date, immunotherapeutic strategies directed against T-cells have shown limited effect in soft tissue sarcoma. Our observations suggest that immunomodulatory agents focusing on macrophages may be worthwhile for further investigations in this tumor type. Further studies exploring the prognostic and predictive significance of CD20⁺ B cells are warranted.

Regorafenib for the Treatment of Sarcoma

OPINION STATEMENT

Sarcomas are a rare group of tumors with many subtypes, conventionally classified into soft-tissue sarcomas and bone sarcomas. Chemotherapeutic regimens form the mainstay of systemic therapy but are not well defined beyond the first-line setting and clinical outcomes are variable. Tyrosine kinase inhibitors (TKIs), with a broad inhibition profile which have been shown to target tumor angiogenesis, have an established role in the treatment of sarcomas without characteristic driver alterations. One such TKI, regorafenib, has been evaluated in sarcomas and clinical data are discussed in this review. An overview of regorafenib data from five phase 2 and one phase 1b clinical trials in over 10 sarcoma subtypes (both soft-tissue and bone) in adult and pediatric patients is reviewed. Regorafenib demonstrated clinical benefit in patients with non-adipocytic soft-tissue sarcomas, osteosarcoma and Ewing sarcoma who had progressed on prior therapy. Patients with otherwise limited treatment options may therefore benefit from regorafenib therapy.

Novel Therapeutics in the Treatment of Uterine Sarcoma

Uterine sarcomas reflect the diversity of sarcoma as a whole. The most common histologies include leiomyosarcoma, high- and low-grade endometrial stromal sarcoma, and adenosarcoma. These are clinically and biologically heterogeneous diseases that are challenging to treat in the advanced setting. Recent advances in our understanding of the cancer biology of uterine sarcomas has improved diagnostic evaluation and therapeutic management. Promising approaches for patients with advanced uterine leiomyosarcoma include targeting DNA damage repair pathways and depleting immunosuppressive macrophage populations. A subset of endometrial stromal sarcomas harbor potentially actionable alterations in the Wnt, cyclin D-CDK4/6-Rb, and MDM2-p53 pathways. There remains an urgent need to translate molecular findings into prospective clinical trials of novel agents for patients with these diseases; progress will depend on academic collaborations and enrollment of patients with uterine sarcoma in biomarker-driven basket studies.

A Phase 1/2 Trial Combining Avelumab and Trabectedin for Advanced Liposarcoma and Leiomyosarcoma

PURPOSE

Leiomyosarcoma (LMS) and liposarcoma (LPS) frequently express PD-L1 but are generally resistant to PD-1/PD-L1 inhibition (ICI). Trabectedin is FDA-approved for LMS and LPS. This study aimed to evaluate the safety and efficacy of trabectedin with anti-PD-L1 antibody avelumab in patients with advanced LMS and LPS.

PATIENTS AND METHODS

A single-arm, open-label, Phase 1/2 study tested avelumab with trabectedin for advanced LMS and LPS. The phase I portion evaluated safety and feasibility of trabectedin (1, 1.2 and 1.5 mg/m2) with avelumab at standard dosing. Primary endpoint of the phase II portion was objective response rate (ORR) by RECIST 1.1. Correlative studies included T-cell receptor sequencing (TCRseq), multiplex immunohistochemistry, and tumor gene expression.

RESULTS

33 patients were evaluable; 24 with LMS (6 uterine and 18 non-uterine) and 11 with LPS. In Phase 1, dose limiting toxicities (DLTs) were observed in 2 of 6 patients at both trabectedin 1.2 and 1.5 mg/m2. The recommended Phase 2 dose (RP2D) was 1.0 mg/m2 trabectedin and 800 mg avelumab. Of 23 patients evaluable at RP2D, three (13%) had partial response (PR), ten (43%) had stable disease (SD) as best response. 6-month PFS was 52%; median PFS was 8.3 months. Patients with PR had higher Simpson Clonality score on TCRseq from peripheral blood mononuclear cells (PBMC) versus those with SD (0.182 vs 0.067, p = 0.02) or PD (0.182 vs 0.064, p = 0.01).

CONCLUSIONS

Although the trial did not meet the primary ORR endpoint, PFS compared favorably to prior studies of trabectedin warranting further investigation.

Immunologic constant of rejection signature is prognostic in soft-tissue sarcoma and refines the CINSARC signature

BACKGROUND

Soft-tissue sarcomas (STSs) are heterogeneous and aggressive tumors, with high metastatic risk. The immunologic constant of rejection (ICR) 20-gene signature is a signature of cytotoxic immune response. We hypothesized that ICR might improve the prognostic assessment of early-stage STS.

METHODS

We retrospectively applied ICR to 1455 non-metastatic STS and searched for correlations between ICR classes and clinicopathological and biological variables, including metastasis-free survival (MFS).

RESULTS

Thirty-four per cent of tumors were classified as ICR1, 27% ICR2, 24% ICR3, and 15% ICR4. These classes were associated with patients' age, pathological type, and tumor depth, and an enrichment from ICR1 to ICR4 of quantitative/qualitative scores of immune response. ICR1 class was associated with a 59% increased risk of metastatic relapse when compared with ICR2-4 class. In multivariate analysis, ICR classification remained associated with MFS, as well as pathological type and Complexity Index in Sarcomas (CINSARC) classification, suggesting independent prognostic value. A prognostic clinicogenomic model, including the three variables, was built in a learning set (n=339) and validated in an independent set (n=339), showing greater prognostic precision than each variable alone or in doublet. Finally, connectivity mapping analysis identified drug classes potentially able to reverse the expression profile of poor-prognosis tumors, such as chemotherapy and targeted therapies.

CONCLUSION

ICR signature is independently associated with postoperative MFS in early-stage STS, independently from other prognostic features, including CINSARC. We built a robust prognostic clinicogenomic model integrating ICR, CINSARC, and pathological type, and suggested differential vulnerability of each prognostic group to different systemic therapies.

Trabectedin plus durvalumab in patients with advanced pretreated soft tissue sarcoma and ovarian carcinoma (TRAMUNE): an open-label, multicenter phase Ib study

PURPOSE

Trabectedin has shown pre-clinical synergy with immune-checkpoint inhibitors in pre-clinical models.

EXPERIMENTAL DESIGN

TRAMUNE is a phase Ib study investigating trabectedin combined with durvalumab trough a dose-escalation phase and two expansion cohorts (soft tissue sarcoma and ovarian carcinoma). Trabectedin was given at three dose levels (1 mg/m2, 1.2 mg/m2 and 1.5 mg/m2) on day 1, in combination with durvalumab, 1120 mg on day 2, every 3 weeks. The primary endpoints were the recommended phase II dose (RP2D) of trabectedin combined with durvalumab and the objective response rate (ORR) as per RECIST 1.1. The secondary endpoints included safety, 6-month progression-free rate (PFR), progression-free survival (PFS), overall survival, and biomarker analyses.

RESULTS

40 patients were included (dose escalation: n=9; STS cohort: n=16; ovarian cohort: n=15, 80% platinum resistant/refractory). The most frequent toxicities were grade 1-2 fatigue, nausea, neutropenia, and alanine/aspartate aminotransferase increase. One patient experienced a dose-limiting toxicity at dose level 2. Trabectedin at 1.2 mg/m2 was selected as the RP2D. In the STS cohort, 43% of patients experienced tumor shrinkage, the ORR was 7% (95% CI 0.2 - 33.9) and the 6-month PFR 28.6% (95% CI 8.4-58.1). In the ovarian carcinoma cohort, 43% of patients experienced tumor shrinkage, the ORR was 21.4% (95% CI 4.7 - 50.8) and the 6-month PFR 42.9% (95% CI 17.7 - 71.1). Baseline levels of PD-L1 expression and CD8-positive T-cell infiltrates were associated with PFS in ovarian carcinoma patients.

CONCLUSIONS

Combining trabectedin and durvalumab is manageable. Promising activity is observed in platinum-refractory ovarian carcinoma patients.

Novel Insights into the Immunotherapy of Soft Tissue Sarcomas: Do We Need a Change of Perspective?

Soft tissue sarcomas (STSs) are rare mesenchymal tumors. With more than 80 histological subtypes of STSs, data regarding novel biomarkers of strong prognostic and therapeutic value are very limited. To date, the most important prognostic factor is the tumor grade, and approximately 50% of patients that are diagnosed with high-grade STSs die of metastatic disease within five years. Systemic chemotherapy represents the mainstay of metastatic STSs treatment for decades but induces response in only 15–35% of the patients, irrespective of the histological subtype. In the era of immunotherapy, deciphering the immune cell signatures within the STSs tumors may discriminate immunotherapy responders from non-responders and different immunotherapeutic approaches could be combined based on the predominant cell subpopulations infiltrating the STS tumors. Furthermore, understanding the immune diversity of the STS tumor microenvironment (TME) in different histological subtypes may provide a rationale for stratifying patients according to the TME immune parameters. In this review, we introduce the most important immune cell types infiltrating the STSs tumors and discuss different immunotherapies, as well as promising clinical trials, that would target these immune cells to enhance the antitumor immune responses and improve the prognosis of metastatic STSs patients.

Resistance to Immune Checkpoint Blockade in Uterine Leiomyosarcoma: What Can We Learn from Other Cancer Types?

The onset of immune checkpoint blockade (ICB) therapy over the last decade has transformed the therapeutic landscape in oncology. ICB has shown unprecedented clinical activity and durable responses in a variety of difficult-to-treat cancers. However, despite these promising long-term responses, a majority of patients fail to respond to single-agent therapy, demonstrating primary or acquired resistance. Uterine leiomyosarcoma (uLMS) is a rare high-risk gynecological cancer with very limited treatment options. Despite research indicating a strong potential for ICB in uLMS, a clinical trial assessing the response to immunotherapy with single-agent nivolumab in advanced-stage uLMS showed no clinical benefit. Many mechanisms of resistance to ICB have been characterized in a variety of tumor types, and many more continue to be uncovered. However, the mechanisms of resistance to ICB in uLMS remain largely unexplored. By elucidating and targeting mechanisms of resistance, treatments can be tailored to improve clinical outcomes. Therefore, in this review we will explore what is known about the immunosuppressive microenvironment of uLMS, link these data to possible resistance mechanisms extrapolated from other cancer types, and discuss potential therapeutic strategies to overcome resistance.

Role of Tumor-Associated Macrophages in Sarcomas

Simple Summary

Recent studies have shown the pro-tumoral role of tumor-associated macrophages (TAMs) not only in major types of carcinomas but also in sarcomas. Several types of TAM-targeted drugs have been investigated under clinical trials, which may represent a novel therapeutic approach for bone and soft-tissue sarcomas.

Abstract

Sarcomas are complex tissues in which sarcoma cells maintain intricate interactions with their tumor microenvironment. Tumor-associated macrophages (TAMs) are a major component of tumor-infiltrating immune cells in the tumor microenvironment and have a dominant role as orchestrators of tumor-related inflammation. TAMs promote tumor growth and metastasis, stimulate angiogenesis, mediate immune suppression, and limit the antitumor activity of conventional chemotherapy and radiotherapy. Evidence suggests that the increased infiltration of TAMs and elevated expression of macrophage-related genes are associated with poor prognoses in most solid tumors, whereas evidence of this in sarcomas is limited. Based on these findings, TAM-targeted therapeutic strategies, such as inhibition of CSF-1/CSF-1R, CCL2/CCR2, and CD47/SIRPα, have been developed and are currently being evaluated in clinical trials. While most of the therapeutic challenges that target sarcoma cells have been unsuccessful and the prognosis of sarcomas has plateaued since the 1990s, several clinical trials of these strategies have yielded promising results and warrant further investigation to determine their translational benefit in sarcoma patients. This review summarizes the roles of TAMs in sarcomas and provides a rationale and update of TAM-targeted therapy as a novel treatment approach for sarcomas.

Immune Checkpoint Inhibitory Therapy in Sarcomas: Is There Light at the End of the Tunnel?

Soft tissue and bone sarcomas are a very heterogeneous group of tumors with many subtypes for which diagnosis and treatment remains a very challenging task. On top of that, the treatment choices are limited, and the prognosis of aggressive sarcomas remains poor. Immune checkpoint inhibitors (ICIs) have drawn a lot of attention last years because of their promising response rates and their durable effects. ICIs are currently widely used in the daily routine practice for the treatment of a different malignancies, such as melanoma, Hodgkin lymphoma, and non-small cell lung carcinoma. Still, ICIs are not included in the standard treatment protocols of the different sarcoma types. However, a plethora of clinical trials investigates the clinical benefit of ICIs in sarcomas. There is clear need to develop predictive biomarkers to determine which sarcoma patients are most likely to benefit from immune checkpoint blockade. This review will focus on (i) the clinical trial results on the use of ICIs in different sarcoma types; and on (ii) possible biomarkers predictive for the effectiveness of these drugs in sarcomas.

Immunotherapeutic strategies for sarcoma: current perspectives

There are more than 100 sarcoma subtypes, each of which is uncommon and challenging to diagnose. Most patients with locally advanced and unresectable sarcomas are still treated with cytotoxic chemotherapy and have low long-term survival. Therefore, novel therapeutic methods are needed to improve the prognosis of patients with sarcomas. Immunotherapy is increasingly recognized as have an essential role in the treatment of malignant tumors. Emerging strategies, such as immune checkpoint inhibitors, vaccines, and adoptive cell therapies have been investigated for the treatment of sarcomas. Advances in these immunotherapies have provided a better understanding of how immuno-oncology can be best applied to the treatment of sarcomas, including their potential as adjuvant therapies in combination strategies. In this review, we discuss the immune microenvironment and how it relates to immunoresponsiveness, focusing on the advances in immunotherapy (immune checkpoint inhibitors, vaccines and adoptive cell therapies), the use of which will hopefully lead to improved outcomes for patients with sarcomas.

Tumor-associated macrophages and macrophage-related immune checkpoint expression in sarcomas

Early trials for immune checkpoint inhibitors in sarcomas have delivered mixed results, and efforts to improve outcomes now look to combinatorial strategies with novel immunotherapeutics, including some that target macrophages. To enhance our understanding of the sarcoma immune landscape, we quantified and characterized tumor-associated macrophage infiltration and expression of the targetable macrophage-related immune checkpoint CD47/SIRPα across sarcoma types. We surveyed immunohistochemical expression of CD68, CD163, CD47, and SIRPα in tissue microarrays of 1242 sarcoma specimens (spanning 24 types). Non-translocation sarcomas, particularly undifferentiated pleomorphic sarcoma and dedifferentiated liposarcoma, had significantly higher counts of both CD68+ and CD163+ macrophages than translocation-associated sarcomas. Across nearly all sarcoma types, macrophages outnumbered tumor-infiltrating lymphocytes and CD163+ (M2-like) macrophages outnumbered CD68+ (M1-like) macrophages. These findings were supported by data from The Cancer Genome Atlas, which showed a correlation between increasing macrophage contributions to immune infiltration and several measures of DNA damage. CD47 expression was bimodal, with most cases showing either 0% or >90% tumor cell staining, and the highest CD47 scores were observed in chordoma, angiosarcoma, and pleomorphic liposarcoma. SIRPα scores correlated well with CD47 expression. Given the predominance of macrophage infiltrates over tumor-infiltrating lymphocytes, the bias toward M2-like (immunosuppressive) macrophage polarization, and the generally high scores for CD47 and SIRPα, macrophage-focused immunomodulatory agents, such as CD47 or IDO-1 inhibitors, may be particularly worthwhile to pursue in sarcoma patients, alone or in combination with lymphocyte-focused agents.

An immunosuppressive macrophage profile attenuates the prognostic impact of CD20-positive B cells in human soft tissue sarcoma

Background

Immune cells can regulate disease progression and response to treatment in multiple tumor types, but their activities in human soft tissue sarcoma are poorly characterized.

Methods

Marker-defined immune cell subsets were characterized from a tumor microenvironmental perspective in two independent cohorts of human soft tissue sarcoma by multiplex IHC, quantitative PCR and/or bioinformatics.

Results

B cell profiling revealed a prognostic role for CD20 protein (cohort 1, 33 patients) and MS4A1 gene expression (cohort 2, 265 patients). Multiplex IHC and gene correlation analysis supported a role in antigen presentation, immune cell differentiation and T cell activation. The prognostic role of MS4A1 expressing B cells was only observed in an IL10^low, PTGS2^low or CD163^low tumor microenvironment according to the transcriptomic data. IL10 levels consistently correlated with the M2-like macrophage marker CD163, which also defined the majority of macrophages. A polarization of these cells toward a pro-tumoral phenotype was further supported by lack of correlation between CD163 and M1 markers like NOS2, as well as by low abundance of CD80 positive cells in tissue.

Conclusions

Analysis of CD20/MS4A1 expression in soft tissue sarcoma merits further attention as a promising candidate prognostic tool for survival, but not in patients with a pronounced immunosuppressive tumor microenvironment. Macrophages are ubiquitous and polarized toward a protumoral phenotype. This provides a rationale for further studies on B cell function and immunotherapy targeting M2-polarized macrophages.

Electronic supplementary material

The online version of this article (10.1007/s00262-019-02322-y) contains supplementary material, which is available to authorized users.

More Than 50 Subtypes of Soft Tissue Sarcoma: Paving the Path for Histology-Driven Treatments

Sarcomas are a diverse group of cancers with mesenchymal origin. Although sarcomas comprise less than 1% of cancers, there are more than 50 different subtypes that are quite different from one another in terms of both their biology and clinical behavior. Historically, the need for adequate patient numbers in clinical trials has pushed sarcoma researchers to lump these very different malignancies together and treat the patients using a "one-size-fits-all" approach. However, with improvements in our scientific understanding, we are finally ready for a histology-tailored therapeutic approach to these complex diseases. In this review, we discuss key advances in our understanding of the biology underlying selected sarcoma subtypes and how targeting these subtypes is relevant therapeutically with respect to both molecularly targeted agents as well as immunotherapy.

Emerging Targeted and Immune-Based Therapies in Sarcoma

Soft tissue and bone sarcomas are malignancies of mesenchymal origin, and more than 50 subtypes are defined. For most sarcomas, locally advanced or unresectable disease is still treated with cytotoxic chemotherapy. Recently, our understanding of subtype-specific cancer biology has expanded, and it has revealed distinct molecular alterations responsible for tumor initiation and progression. These findings have motivated the development of targeted therapies that are being evaluated in subtype-specific or biomarker-driven clinical trials. Indeed, the spectrum of targeted drug development in sarcoma now spans many of the most active paradigms in cancer research and includes agents that target cancer-related vulnerabilities in receptor tyrosine kinases and intracellular signaling pathways, epigenetics, metabolism, nuclear-cytoplasmic transport, and many others. Our understanding of the sarcoma immune microenvironment and heterogeneous mechanisms of tumor immune evasion has also expanded. Although a subset of sarcomas appears inflamed and responsive to immune checkpoint blockade with programmed death 1 (PD-1) targeted agents, novel immunotherapies and combinations likely will be needed for most subtypes. A variety of approaches—including targeting immune checkpoints other than PD-1; modulating tumor-associated macrophage phenotype from tumor-promoting to tumor-suppressive status; using cellular-based therapies, such as chimeric antigen and high-affinity T-cell receptors to deepen the adaptive immune response; and reinvigorating older approaches, such as vaccines and oncolytic virus-based treatments—are being investigated. The goal of these new approaches is to harness subtype-specific insights into cancer and immune biology to bring more effective and less toxic treatments to the clinic for the benefit of patients with sarcoma.

Immune checkpoint inhibitors in sarcomas: in quest of predictive biomarkers

Sarcomas are a rare group of tumors of mesenchymal origin. Metastatic sarcomas are often difficult to treat and unresponsive to standard radio- and chemotherapy, resulting in a poor survival rate for patients. Novel treatments with immune checkpoint inhibitors have been proven to prolong survival of patients with a variety of cancers, including metastatic melanoma, lung, and renal cell carcinoma. Since immune checkpoint inhibitors could provide a novel treatment option for patients with sarcomas, clinical trials investigating their efficacy in these group of tumors are ongoing. However, the discrimination of patients that are the most likely to respond to these treatments is still an obstacle in the design of clinical trials. In this review, we provide a brief overview of the mechanisms of action of immune checkpoint inhibitors and discuss the proposed biomarkers of therapy response, such as lymphocytic infiltration, intratumoral PD-L1 expression, and mutational load in sarcomas.

T-cell infiltration and clonality correlate with programmed cell death protein 1 and programmed death-ligand 1 expression in patients with soft tissue sarcomas

BACKGROUND

Patients with metastatic sarcomas have poor outcomes and although the disease may be amenable to immunotherapies, information regarding the immunologic profiles of soft tissue sarcoma (STS) subtypes is limited.

METHODS

The authors identified patients with the common STS subtypes: leiomyosarcoma, undifferentiated pleomorphic sarcoma (UPS), synovial sarcoma (SS), well‐differentiated/dedifferentiated liposarcoma, and myxoid/round cell liposarcoma. Gene expression, immunohistochemistry for programmed cell death protein (PD‐1) and programmed death‐ligand 1 (PD‐L1), and T‐cell receptor Vβ gene sequencing were performed on formalin‐fixed, paraffin‐embedded tumors from 81 patients. Differences in liposarcoma subsets also were evaluated.

RESULTS

UPS and leiomyosarcoma had high expression levels of genes related to antigen presentation and T‐cell infiltration. UPS were found to have higher levels of PD‐L1 (P≤.001) and PD‐1 (P≤.05) on immunohistochemistry and had the highest T‐cell infiltration based on T‐cell receptor sequencing, significantly more than SS, which had the lowest (P≤.05). T‐cell infiltrates in UPS also were more oligoclonal compared with SS and liposarcoma (P≤.05). A model adjusted for STS histologic subtype found that for all sarcomas, T‐cell infiltration and clonality were highly correlated with PD‐1 and PD‐L1 expression levels (P≤.01).

CONCLUSIONS

In the current study, the authors provide the most detailed overview of the immune microenvironment in sarcoma subtypes to date. UPS, which is a more highly mutated STS subtype, provokes a substantial immune response, suggesting that it may be well suited to treatment with immune checkpoint inhibitors. The SS and liposarcoma subsets are less mutated but do express immunogenic self‐antigens, and therefore strategies to improve antigen presentation and T‐cell infiltration may allow for successful immunotherapy in patients with these diagnoses. Cancer 2017;123:3291‐304. © 2017 The Authors. Cancer published by Wiley Periodicals, Inc. on behalf of American Cancer Society. This is an open access article under the terms of the Creative Commons Attribution NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.

To the author's knowledge, the current study provides the most comprehensive characterization of the sarcoma tumor immune microenvironment to date through the use of gene expression analysis, immunohistochemistry, and T‐cell receptor sequencing. The results demonstrate that some sarcoma subtypes, such as synovial sarcoma, are immunologically quiet, whereas others, such as undifferentiated pleomorphic sarcoma, are highly inflammatory and could be susceptible to immune checkpoint inhibition.

Immunotherapy with single agent nivolumab for advanced leiomyosarcoma of the uterus: Results of a phase 2 study

BACKGROUND

Immunotherapy has changed the therapeutic landscape in oncology. Advanced uterine leiomyosarcoma (ULMS) remains an incurable disease in most cases, and despite new drug approvals, improvements in overall survival have been modest at best. The goal of this study was to evaluate programmed-death 1 (PD-1) inhibition with nivolumab in this patient population.

METHODS

This single-center phase 2 trial completed enrollment between May and October 2015. Patients received 3 mg/kg of intravenous nivolumab on day 1 of each 2-week cycle until disease progression or unacceptable toxicity. The primary endpoint was objective response rate. We assessed PD-1, PD-ligand 1 (PD-L1), and PD-L2 expression in archival tumor samples and variations in immune-phenotyping of circulating immune cells during treatment.

RESULTS

Twelve patients were enrolled in the first stage of the 2-stage design. A median of 5 (range, 2-6) 2-week cycles of nivolumab were administered. Of the 12 patients, none responded to treatment. The overall median progression-free survival was 1.8 months (95% confidence interval, 0.8-unknown). The study did not open the second stage due to lack of benefit as defined by the statistical plan. Archival samples were available for 83% of patients. PD-1 (>3% of cells), PD-L1, and PD-L2 (>5% and >10% of tumor cells, respectively) expression were observed in 20%, 20%, and 90% of samples, respectively. No significant differences were observed between pre- and posttreatment cell phenotypes.

CONCLUSION

Single-agent nivolumab did not demonstrate a benefit in this cohort of previously treated advanced ULMS patients. Further biomarker-driven approaches and studies evaluating combined immune checkpoint-modulators should be considered. Cancer 2017;123:3285-90. © 2017 American Cancer Society.

Immunotherapy for Soft Tissue Sarcoma: Tomorrow Is Only a Day Away

Despite the advances taking place for patients with many types of cancer, to date there has been little success in meeting the great need for novel treatments of advanced soft tissue sarcoma with effective immunologic therapies. Here, we review recent clinical and preclinical data that indicate immune responses against sarcomas occur spontaneously and can also be successfully provoked. Efforts to manipulate the sarcoma immune microenvironment have the potential to eradicate disease and may also sensitize tumors to other tumor-targeted immunotherapeutic approaches. Other approaches, including vaccines and genetic engineering of T cells, offer a promising opportunity to actively direct cytotoxic lymphocytes toward antigen-bearing sarcomas. Drawing parallels with recent advances made in other cancer types, we identify ways in which sarcomas can be included in the ongoing immunotherapy revolution.

Tumor-infiltrating dendritic cells in cancer pathogenesis

Dendritic cells (DCs) play a pivotal role in the tumor microenvironment, which is known to affect disease progression in many human malignancies. Infiltration by mature, active DCs into the tumors confers an increase in immune activation and recruitment of disease-fighting immune effector cells and pathways. DCs are the preferential target of infiltrating T cells. However, tumor cells have means of suppressing DC function or of altering the tumor microenvironment in such a way that immune-suppressive DCs are recruited. Advances in understanding these changes have led to promising developments in cancer-therapeutic strategies targeting tumor-infiltrating DCs to subdue their immunosuppressive functions and enhance their immune-stimulatory capacity.