Immunotherapy in Sarcoma: Current Data and Promising Strategies

Traditionally sarcomas have been considered immunologically quiet tumours, with low tumour mutational burden (TMB) and an immunosuppressive tumour microenvironment (TME), consisting of decreased T-cell infiltration and elevated levels of H1F1α, macrophages and neutrophils.1,2 However, research has shown that a subset of sarcomas are immunologically 'hot' with either high TMB, PDL-1 expression, CD8+ T cells or presence of tertiary lymphoid structures (TLS) demonstrating sensitivity to immunotherapy.3,4 Here, we review the current evidence for immunotherapy use in bone sarcomas (BS) and soft tissue sarcomas (STS), with immune checkpoint inhibitors (ICI) and adoptive cellular therapies including engineered T-cell therapies, chimeric antigen receptor (CAR) T-cell therapies, tumour infiltrating lymphocytes (TILs) and cancer vaccines and biomarkers of response.

Cancer testis antigens: Emerging therapeutic targets leveraging genomic instability in cancer

Cancer care has witnessed remarkable progress in recent decades, with a wide array of targeted therapies and immune-based interventions being added to the traditional treatment options such as surgery, chemotherapy, and radiotherapy. However, despite these advancements, the challenge of achieving high tumor specificity while minimizing adverse side effects continues to dictate the benefit-risk balance of cancer therapy, guiding clinical decision making. As such, the targeting of cancer testis antigens (CTAs) offers exciting new opportunities for therapeutic intervention of cancer since they display highly tumor specific expression patterns, natural immunogenicity and play pivotal roles in various biological processes that are critical for tumor cellular fitness. In this review, we delve deeper into how CTAs contribute to the regulation and maintenance of genomic integrity in cancer, and how these mechanisms can be exploited to specifically target and eradicate tumor cells. We review the current clinical trials targeting aforementioned CTAs, highlight promising pre-clinical data and discuss current challenges and future perspectives for future development of CTA-based strategies that exploit tumor genomic instability.

Role of Immunotherapy in Sarcomas

Sarcomas are a group of malignancies of mesenchymal origin with a plethora of subtypes. Given the sheer heterogeneity of various subtypes and the rarity of the disease, the management of sarcomas has been challenging, with poor patient outcomes. Surgery, radiation therapy and chemotherapy have remained the backbone of treatment in patients with sarcoma. The introduction of immunotherapy has revolutionized the treatment of various solid and hematological malignancies. In this review, we discuss the basics of immunotherapy and the immune microenvironment in sarcomas; various modalities of immunotherapy, like immune checkpoint blockade, oncolytic viruses, cancer-targeted antibodies, vaccine therapy; and adoptive cell therapies like CAR T-cell therapy, T-cell therapy, and TCR therapy.

Immune Cells in the Tumor Microenvironment of Soft Tissue Sarcomas

Soft tissue sarcomas (STSs) are a rare heterogeneous group of malignant neoplasms characterized by their aggressive course and poor response to treatment. This determines the relevance of research aimed at studying the pathogenesis of STSs. By now, it is known that STSs is characterized by complex relationships between the tumor cells and immune cells of the microenvironment. Dynamic interactions between tumor cells and components of the microenvironment enhance adaptation to changing environmental conditions, which provides the high aggressive potential of STSs and resistance to antitumor therapy. Today, active research is being conducted to find effective antitumor drugs and to evaluate the possibility of using therapy with immune cells of STS. The difficulty in assessing the efficacy of new antitumor options is primarily due to the high heterogeneity of this group of malignant neoplasms. Studying the role of immune cells in the microenvironment in the progression STSs and resistance to antitumor therapies will provide the discovery of new biomarkers of the disease and the prediction of response to immunotherapy. In addition, it will help to initially divide patients into subgroups of good and poor response to immunotherapy, thus avoiding wasting precious time in selecting the appropriate antitumor agent.

Synovial sarcoma: characteristics, challenges, and evolving therapeutic strategies

Synovial sarcoma (SS) is a rare and aggressive disease that accounts for 5%-10% of all soft tissue sarcomas. Although it can occur at any age, it typically affects younger adults and children, with a peak incidence in the fourth decade of life. In >95% of cases, the oncogenic driver is a translocation between chromosomes X and 18 that leads to the formation of the SS18::SSX fusion oncogenes. Early and accurate diagnosis is often a challenge; optimal outcomes are achieved by referral to a specialist center for diagnosis and management by a multidisciplinary team as soon as SS is suspected. Surgery with or without radiotherapy and/or chemotherapy can be effective in localized disease, especially in children. However, the prognosis in the advanced stages is poor, with treatment strategies that have relied heavily on traditional cytotoxic chemotherapies. Therefore, there is an unmet need for novel effective management strategies for advanced disease. An improved understanding of disease pathology and its molecular basis has paved the way for novel targeted agents and immunotherapies that are being investigated in clinical trials. This review provides an overview of the epidemiology and characteristics of SS in children and adults, as well as the patient journey from diagnosis to treatment. Current and future management strategies, focusing particularly on the potential of immunotherapies to improve clinical outcomes, are also summarized.

Best Practices and Considerations for Clinical Pharmacology and Pharmacometric Aspects for Optimal Development of CAR-T and TCR-T Cell Therapies: An Industry Perspective

With the promise of a potentially "single dose curative" paradigm, CAR-T cell therapies have brought a paradigm shift in the treatment and management of hematological malignancies. Both CAR-T and TCR-T cell therapies have also made great progress toward the successful treatment of solid tumor indications. The field is rapidly evolving with recent advancements including the clinical development of "off-the-shelf" allogeneic CAR-T therapies that can overcome the long and difficult "vein-to-vein" wait time seen with autologous CAR-T therapies. There are unique clinical pharmacology, pharmacometric, bioanalytical, and immunogenicity considerations and challenges in the development of these CAR-T and TCR-T cell therapies. Hence, to help accelerate the development of these life-saving therapies for the patients with cancer, experts in this field came together under the umbrella of International Consortium for Innovation and Quality in Pharmaceutical Development (IQ) to form a joint working group between the Clinical Pharmacology Leadership Group (CPLG) and the Translational and ADME Sciences Leadership Group (TALG). In this white paper, we present the IQ consortium perspective on the best practices and considerations for clinical pharmacology and pharmacometric aspects toward the optimal development of CAR-T and TCR-T cell therapies.

Children's Oncology Group's 2023 blueprint for research: Soft tissue sarcomas

In the United States, approximately 850-900 children and adolescents each year are diagnosed with soft tissue sarcomas (STS). STS are divided into rhabdomyosarcoma (RMS) and non-rhabdomyosarcoma STS (NRSTS). RMS and NRSTS are risk stratified into low-, intermediate-, and high-risk categories, with 5-year survival rates of approximately 90%, 50%-70%, and 20%, respectively. Recent key achievements from the Children's Oncology Group (COG) STS Committee include the identification of new molecular prognostic factors for RMS, development and validation of a novel risk stratification system for NRSTS, successful completion of a collaborative NRSTS clinical trial with adult oncology consortia, and collaborative development of the INternational Soft Tissue SaRcoma ConsorTium (INSTRuCT). Current COG trials for RMS are prospectively evaluating a new risk stratification system that incorporates molecular findings, de-intensification of therapy for a very low-risk subgroup, and augmented therapy approaches for intermediate- and high-risk RMS. Trials for NRSTS exploring novel targets and local control modalities are in development.

Durable control of metastases in an HLA-A2+ patient with refractory melanoma after low-dose radiotherapy in combination with MAGE-A4 T cell therapy: a case report

There is no currently approved adoptive cellular therapy for solid tumors. Pre-clinical and clinical studies have demonstrated that low-dose radiotherapy (LDRT) can enhance intratumoral T cell infiltration and efficacy. This case report describes a 71-year-old female patient with rectal mucosal melanoma that had developed metastases to liver, lung, mediastinum, axillary nodes, and brain. After systemic therapies had failed, she enrolled in the radiation sub-study of our phase-I clinical trial exploring the safety and efficacy of afamitresgene autoleucel (afami-cel), genetically engineered T cells with a T cell receptor (TCR) targeting the MAGE-A4 tumor antigen in patients with advanced malignancies (NCT03132922). Prior to the infusion of afami-cel, she received concurrent lymphodepleting chemotherapy and LDRT at 5.6 Gy/4 fractions to the liver. Time to partial response was 10 weeks, and duration of overall response was 18.4 weeks. Although the patient progressed at 28 weeks, the disease was well controlled after high-dose radiotherapy to liver metastases and checkpoint inhibitors. As of the last follow-up, she remains alive over two years after LDRT and afami-cel therapy. This report suggests that afami-cel in combination with LDRT safely enhanced clinical benefit. This provides evidence for further exploring the benefit of LDRT in TCR-T cell therapy.

Innovative Breakthroughs for the Treatment of Advanced and Metastatic Synovial Sarcoma

Synovial sarcoma (SyS) is a rare aggressive soft tissue sarcoma carrying the chromosomal translocation t(X;18), encoding the fusion transcript SS18::SSX. The fusion oncoprotein interacts with both BAF enhancer complexes and polycomb repressor complexes, resulting in genome-wide epigenetic perturbations and a unique altered genetic signature. Over 80% of the patients are initially diagnosed with localized disease and have a 5-year survival rate of 70-80%, but metastatic relapse occurs in 50% of the cases. Advanced, unresectable, or metastatic disease has a 5-year survival rate below 10%, representing a critical issue. This review summarizes the molecular mechanisms behind SyS and illustrates current treatments in front line, second line, and beyond settings. We analyze the use of immune check point inhibitors (ICI) in SyS that do not behave as an ICI-sensitive tumor, claiming the need for predictive genetic signatures and tumor immune microenvironment biomarkers. We highlight the clinical translation of innovative technologies, such as proteolysis targeting chimera (PROTAC) protein degraders or adoptive transfer of engineered immune cells. Adoptive cell transfer of engineered T-cell receptor cells targeting selected cancer/testis antigens has shown promising results against metastatic SyS in early clinical trials and further improvements are awaited from refinements involving immune cell engineering and tumor immune microenvironment enhancement.

Current Landscape of Immunotherapy for Advanced Sarcoma

There is substantial heterogeneity between different subtypes of sarcoma regarding their biological behavior and microenvironment, which impacts their responsiveness to immunotherapy. Alveolar soft-part sarcoma, synovial sarcoma and undifferentiated pleomorphic sarcoma show higher immunogenicity and better responses to checkpoint inhibitors. Combination strategies adding immunotherapy to chemotherapy and/or tyrosine-kinase inhibitors globally seem superior to single-agent schemes. Therapeutic vaccines and different forms of adoptive cell therapy, mainly engineered TCRs, CAR-T cells and TIL therapy, are emerging as new forms of immunotherapy for advanced solid tumors. Tumor lymphocytic infiltration and other prognostic and predictive biomarkers are under research.

New therapeutics for soft tissue sarcomas: Overview of current immunotherapy and future directions of soft tissue sarcomas

Soft tissue sarcoma is a rare and aggressive disease with a 40 to 50% metastasis rate. The limited efficacy of traditional approaches with surgery, radiation, and chemotherapy has prompted research in novel immunotherapy for soft tissue sarcoma. Immune checkpoint inhibitors such as anti-CTLA-4 and PD-1 therapies in STS have demonstrated histologic-specific responses. Some combinations of immunotherapy with chemotherapy, TKI, and radiation were effective. STS is considered a ‘cold’, non-inflamed tumor. Adoptive cell therapies are actively investigated in STS to enhance immune response. Genetically modified T-cell receptor therapy targeting cancer testis antigens such as NY-ESO-1 and MAGE-A4 demonstrated durable responses, especially in synovial sarcoma. Two early HER2-CAR T-cell trials have achieved stable disease in some patients. In the future, CAR-T cell therapies will find more specific targets in STS with a reliable response. Early recognition of T-cell induced cytokine release syndrome is crucial, which can be alleviated by immunosuppression such as steroids. Further understanding of the immune subtypes and biomarkers will promote the advancement of soft tissue sarcoma treatment.

Immunotherapy for Soft Tissue Sarcomas: Anti-PD1/PDL1 and Beyond

Sarcomas gather a heterogeneous group of mesenchymal malignant tumors including more than 150 different subtypes. Most of them represent aggressive tumors with poor prognosis at the advanced stage, despite the better molecular characterization of these tumors and the development of molecular-driven therapeutic strategies. During the last decade, immunotherapy has been developed to treat advanced cancers, mainly thanks to immune checkpoint inhibitors (ICI) such as anti-PD1/PDL1 and later to adoptive immune cell therapies. In this review, we aim to summarize the state of the art of immunotherapy in soft tissue sarcomas (STS). Overall, the clinical trials of ICI that included a wide diversity of STS subtypes reported limited efficacy with some outlying responders. Both emerging biomarkers are of interest in selecting good candidates and in the development of combination therapies. Finally, the recent breakthroughs of innovative adoptive therapies in STS seem highly promising.

Trimodality Treatment of Extremity Soft Tissue Sarcoma: Where Do We Go Now?

OPINION STATEMENT

Extremity soft tissue sarcoma (ESTS) constitutes the majority of patients with soft tissue sarcoma (STS). Patients with localized high-grade ESTS > 5 cm in size carry a substantial risk of developing distant metastasis on follow-up. A neoadjuvant chemoradiotherapy approach can enhance local control by facilitating resection of the large and deep locally advanced tumors while trying to address distant spread by treating the micrometastasis for these high-risk ESTS. Preoperative chemoradiotherapy and adjuvant chemotherapy are often used for children with intermediate- or high-risk non-rhabdomyosarcoma soft tissue tumors in North America and Europe. In adults, the cumulative evidence supporting preoperative chemoradiotherapy or adjuvant chemotherapy remains controversial. However, some studies support a possible benefit of 10% in overall survival (OS) for high-risk localized ESTS, especially for those with a probability of 10-year OS < 60% using validated nomograms. Opponents of neoadjuvant chemotherapy argue that it delays curative surgery, compromises local control, and increases the rate of wound complications and treatment-related mortality; however, the published trials do not support these arguments. Most treatment-related side effects can be managed with adequate supportive care. A coordinated multidisciplinary approach involving sarcoma expertise in surgery, radiation, and chemotherapy is required to achieve better outcomes for ESTS. The next generation of clinical trials will shed light on how comprehensive molecular characterization, targeted agents and/or immunotherapy can be integrated into the upfront trimodality treatment to improve outcomes. To that end, every effort should be made to enroll these patients on clinical trials, when available.

TCR-engineered T cell therapy in solid tumors: State of the art and perspectives

T cell engineering has changed the landscape of cancer immunotherapy. Chimeric antigen receptor T cells have demonstrated a remarkable efficacy in the treatment of B cell malignancies in hematology. However, their clinical impact on solid tumors has been modest so far. T cells expressing an engineered T cell receptor (TCR-T cells) represent a promising therapeutic alternative. The target repertoire is not limited to membrane proteins, and intrinsic features of TCRs such as high antigen sensitivity and near-to-physiological signaling may improve tumor cell detection and killing while improving T cell persistence. In this review, we present the clinical results obtained with TCR-T cells targeting different tumor antigen families. We detail the different methods that have been developed to identify and optimize a TCR candidate. We also discuss the challenges of TCR-T cell therapies, including toxicity assessment and resistance mechanisms. Last, we share some perspectives and highlight future directions in the field.

Immunotherapy approaches for rare pediatric solid tumors: advances and future directions

PURPOSE OF REVIEW

Immunotherapy for pediatric tumors is rapidly evolving. From major successes in pediatric hematologic malignancies, immunotherapy utility increased in the pediatric solid tumor landscape. Numerous pediatric solid tumors are defined as rare with limitations in diagnosis and treatment. This review will describe four major immunotherapies used in pediatrics and discuss results seen in rare pediatric tumors. We will also briefly review the challenges of immunotherapy in solid tumors and opportunities to drive this therapy forward.

RECENT FINDINGS

Despite rare success employing immunotherapy for pediatric solid tumors, recently there have been several successes in pediatric rare solid tumors. After describing the evolving landscape of rare pediatric tumors, we will demonstrate the successes or disappointments of immunotherapy. We will describe the mechanism of four immunotherapies used in the pediatrics, followed by the published results. Finally, we will discuss the challenges and opportunities for immunotherapies in pediatric rare tumors.

SUMMARY

Pediatric rare tumors are lacking in treatment options. Despite numerous disappointments utilizing immunotherapies in the more common pediatric solid tumors, there have been several successes within the pediatric rare tumor landscape. Much work is still needed to enhance our understanding and knowledge on utilizing these immunotherapies for pediatric rare solid tumors.

Current and future concepts for the generation and application of genetically engineered CAR-T and TCR-T cells

Adoptive cell therapy (ACT) has seen a steep rise of new therapeutic approaches in its immune-oncology pipeline over the last years. This is in great part due to the recent approvals of chimeric antigen receptor (CAR)-T cell therapies and their remarkable efficacy in certain soluble tumors. A big focus of ACT lies on T cells and how to genetically modify them to target and kill tumor cells. Genetically modified T cells that are currently utilized are either equipped with an engineered CAR or a T cell receptor (TCR) for this purpose. Both strategies have their advantages and limitations. While CAR-T cell therapies are already used in the clinic, these therapies face challenges when it comes to the treatment of solid tumors. New designs of next-generation CAR-T cells might be able to overcome these hurdles. Moreover, CARs are restricted to surface antigens. Genetically engineered TCR-T cells targeting intracellular antigens might provide necessary qualities for the treatment of solid tumors. In this review, we will summarize the major advancements of the CAR-T and TCR-T cell technology. Moreover, we will cover ongoing clinical trials, discuss current challenges, and provide an assessment of future directions within the field.

Autologous T cell therapy for MAGE-A4+ solid cancers in HLA-A*02+ patients: a phase 1 trial

Affinity-optimized T cell receptors can enhance the potency of adoptive T cell therapy. Afamitresgene autoleucel (afami-cel) is a human leukocyte antigen-restricted autologous T cell therapy targeting melanoma-associated antigen A4 (MAGE-A4), a cancer/testis antigen expressed at varying levels in multiple solid tumors. We conducted a multicenter, dose-escalation, phase 1 trial in patients with relapsed/refractory metastatic solid tumors expressing MAGE-A4, including synovial sarcoma (SS), ovarian cancer and head and neck cancer ( NCT03132922 ). The primary endpoint was safety, and the secondary efficacy endpoints included overall response rate (ORR) and duration of response. All patients (N = 38, nine tumor types) experienced Grade ≥3 hematologic toxicities; 55% of patients (90% Grade ≤2) experienced cytokine release syndrome. ORR (all partial response) was 24% (9/38), 7/16 (44%) for SS and 2/22 (9%) for all other cancers. Median duration of response was 25.6 weeks (95% confidence interval (CI): 12.286, not reached) and 28.1 weeks (95% CI: 12.286, not reached) overall and for SS, respectively. Exploratory analyses showed that afami-cel infiltrates tumors, has an interferon-γ-driven mechanism of action and triggers adaptive immune responses. In addition, afami-cel has an acceptable benefit-risk profile, with early and durable responses, especially in patients with metastatic SS. Although the small trial size limits conclusions that can be drawn, the results warrant further testing in larger studies.

What's the latest with investigational drugs for soft tissue sarcoma?

INTRODUCTION

Despite extensive research undertaken in the past 20-30 years, the treatment for soft tissue sarcoma (STS) has remained largely the same, with anthracycline-based chemotherapy remaining the first choice for treating advanced or metastatic STS.

AREAS COVERED

This review focuses on newly approved drugs for STS and current research directions, including recent results of late-phase trials in patients with STS. We cover several different histological subtypes, and we discuss the role of adoptive cell transfer (ACT) therapies for the treatment of synovial and myxoid/round cell (high-grade myxoid) liposarcoma, one of the most promising areas of treatment development to date. We searched clinicaltrials.gov and pubmed.ncbi.nih.gov, as well as recent year proceedings from the annual conferences of the American Society of Clinical Oncology (ASCO), European Society for Medical Oncology (ESMO), and Connective Tissue Oncology Society (CTOS).

EXPERT OPINION

Immune-oncology drugs (IOs) show promise in certain subtypes of STS, but it is recognized that PD-1/PD-L1 axis inhibition is not enough on its own. Better trial stratifications based on the molecular categorization of different subtypes of STS are needed, and more evidence suggests that 'one size fits all' treatment is no longer sustainable in this heterogeneous and aggressive group of tumors.

The diagnosis, classification, and treatment of sarcoma in this era of artificial intelligence and immunotherapy

Soft-tissue sarcomas (STS) represent a group of rare and heterogeneous tumors associated with several challenges, including incorrect or late diagnosis, the lack of clinical expertise, and limited therapeutic options. Digital pathology and radiomics represent transformative technologies that appear promising for improving the accuracy of cancer diagnosis, characterization and monitoring. Herein, we review the potential role of the application of digital pathology and radiomics in managing patients with STS. We have particularly described the main results and the limits of the studies using radiomics to refine diagnosis or predict the outcome of patients with soft-tissue sarcomas. We also discussed the current limitation of implementing radiomics in routine settings. Standard management approaches for STS have not improved since the early 1970s. Immunotherapy has revolutionized cancer treatment; nonetheless, immuno-oncology agents have not yet been approved for patients with STS. However, several lines of evidence indicate that immunotherapy may represent an efficient therapeutic strategy for this group of diseases. Thus, we emphasized the remarkable potential of immunotherapy in sarcoma treatment by focusing on recent data regarding the immune landscape of these tumors. We have particularly emphasized the fact that the development of immunotherapy for sarcomas is not an aspect of histology (except for alveolar soft-part sarcoma) but rather that of the tumor microenvironment. Future studies investigating immunotherapy strategies in sarcomas should incorporate at least the presence of tertiary lymphoid structures as a stratification factor in their design, besides including a strong translational program that will allow for a better understanding of the determinants involved in sensitivity and treatment resistance to immune-oncology agents.

NKp44-based chimeric antigen receptor effectively redirects primary T cells against synovial sarcoma

BACKGROUND

T-cell receptor-engineered T-cell therapies have achieved promising response rates against synovial sarcoma in clinical trials, but their applicability is limited owing to the HLA matching requirement. Chimeric antigen receptor (CAR) can redirect primary T cells to tumor-associated antigens without requiring HLA matching. However, various obstacles, including the paucity of targetable antigens, must be addressed for synovial sarcoma. Ligands for natural killer (NK) cell-activating receptors are highly expressed by tumor cells.

METHODS

The surface expression of ligands for NK cell-activating receptors in synovial sarcoma cell lines was analyzed. We analyzed RNA sequencing data deposited in a public database to evaluate NKp44-ligand expression. Primary T cells retrovirally transduced with CAR targeting NKp44 ligands were evaluated for their functions in synovial sarcoma cells. Alterations induced by various stimuli, including a histone deacetylase inhibitor, a hypomethylating agent, inflammatory cytokines, and ionizing radiation, in the expression levels of NKp44 ligands were investigated.

RESULTS

Ligands for NKp44 and NKp30 were expressed in all cell lines. NKG2D ligands were barely expressed in a single cell line. None of the cell lines expressed NKp46 ligand. Primary synovial sarcoma cells expressed the mRNA of the truncated isoform of MLL5, a known cellular ligand for NKp44. NKp44-based CAR T cells specifically recognize synovial sarcoma cells, secrete interferon-γ, and exert suppressive effects on tumor cell growth. No stimulus altered the expression of NKp44 ligands.

CONCLUSION

NKp44-based CAR T cells can redirect primary human T cells to synovial sarcoma cells. CAR-based cell therapies may be an option for treating synovial sarcomas.

Immunotherapy in Sarcoma: Where Do Things Stand?

Early experiences with modern immunotherapy have been disappointing in trials of unselected sarcoma subtypes. However, remarkable efficacy has been observed with immune checkpoint inhibitors (ICIs) in a subset of patients, with the most promising outcomes to date in alveolar soft part sarcoma, cutaneous angiosarcoma, undifferentiated pleomorphic sarcoma (UPS), and dedifferentiated liposarcoma (dLPS). Adoptive cellular therapies targeting cancer testis antigens have shown promising activity, but only synovial sarcoma (SS) and myxoid/round cell liposarcomas reliably express these targets. The majority of sarcomas are immunologically "cold" with sparse immune infiltration, which may explain the poor response to immunotherapy. Current immunotherapy trials for sarcomas explore combination therapies with checkpoint inhibitors to overcome immune evasion and novel targets in adoptive cellular therapies. The role of tertiary lymphoid structures, PD-L1 expression, tumor mutational burden, microsatellite instability, and tumor lymphocytes as biomarkers for response are areas of active investigation. In this review, we highlight prior and ongoing clinical efforts to improve outcomes with immunotherapy and discuss the current state of understanding for biomarkers to select patients most likely to benefit from this approach.

Immunotherapy in soft tissue sarcoma: current evidence and future perspectives in a variegated family of different tumour

INTRODUCTION

In the last few years steps forward in the knowledge of the biology of soft tissue sarcomas (STS) has led to the development of new therapeutic strategies, including immunotherapy.

AREAS COVERED

This review outlines the recent findings on immunological features and provides a synopsis of the results of clinical trials with different immunotherapy approaches in STS, discussing criticisms and how the efficacy of immunotherapy could be improved.

EXPERT OPINION

The heterogeneity of STS has limited generalized approaches of immunotherapy in the disease. Clinical decisions should encompass a comprehensive characterization of the tumour microenvironment (TME), marked by intra-histotype diversity. Profiling of immune cells, checkpoint molecules and antigen target/HLA expression is deemed to re-shape the classical histotype classification for a selection of the most appropriate immune-based treatment. In a synergistic view, tumour-directed treatments, designed on the genetic and epigenetic histotype make-up, should be monitored for their immunomodulant effect and applied to ensure or amplify immunotherapy response. In light of the dynamic nature of the TME, this immunomonitoring should be conducted at baseline and during treatment, for improved therapeutic decisions and rational sequence of treatment combination, pursuing an immunological marker approach by histotype guidance.

Immunotherapy and Biomarkers in Sarcoma

OPINION STATEMENT

Sarcoma describes a rare and heterogeneous group of diseases. Current treatment options for metastatic sarcoma are quite limited. Conventional treatments with chemotherapy or anti-angiogenic agents result in a non-durable response and a survival rate of approximately 12 to 18 months. In addition, the benefits of such treatments remain limited in some sarcoma subtypes only. Immunotherapy is an emerging treatment for several cancer types with promising outcomes. Studies at the cellular level have shown a relatively high immunogenicity in some subtypes of sarcoma. It is therefore hypothesized that sarcoma may respond to immunotherapy. However, sarcoma is a heterogeneous disease and differences in terms of immunogenicity exist. A multitude of immune-based treatment approaches for sarcoma have been explored. This includes immune checkpoint inhibitors, therapeutic vaccines, and adoptive cell therapy. Single-agent immunotherapy has exhibited efficacy against some sarcoma subtypes, including alveolar soft-part sarcoma, angiosarcoma, and undifferentiated pleomorphic sarcoma. Combination immunotherapy appears superior to single-agent immunotherapy in terms of response, and several ongoing studies of immunotherapy using single/combination immune checkpoint inhibitors and combination with anti-angiogenesis have begun to report beneficial results. Predictive and prognostic biomarkers are also under active investigations, with particular interest in tumor-infiltrating lymphocytes or high tumor mutational burden levels. However, the information is still limited and further studies are needed.

Identification of Novel Modalities Through Bibliometric Analysis for Timely Development of Regulatory Guidance: A Case Study of T Cell Immunity

Background: The mission of medicines regulatory agencies is to ensure the timely access of innovative products for patients to improve public health. Thus, regulators should foresee evolving technologies and build expertise prior to reviewing innovative products. Novel modalities and new classes of therapeutics in biological or cell-based products represent a regulatory challenge because of knowledge gaps, as exemplified by the unexpected cytokine release syndrome in the first-in-human clinical trial of the CD28 super-agonist. Meanwhile, recent treatments harnessing T cell co-signaling pathways provide an opportunity for investigation. Therefore, this study aimed to systematically identify and evaluate novel modalities for T cell immunity to assess the need for regulatory guidance. Methods: A PubMed search was carried out using the query, "immun* AND t lymph*" to select publications. Subsequently, a citation network was created, followed by clustering and text mining to identify the modalities and classes of therapeutics under development. Results and Discussion: Analysis of the top 20 clusters revealed research domains characterized by keywords such as immune checkpoint antibody, chimeric antigen receptor (CAR)-T cells, microbiota, exosome, regulatory T cells, unconventional T cells, and vaccines. After reviewing the pharmacological concepts, clinical trial information, and available guidance, we presented a perspective on the future development of guidance for these domains. Conclusion: Bibliometric analyses identified a set of innovative modalities targeted for drug development with which regulatory guidance is going to catch up. This strategy could help in the successful development of upcoming modalities to ensure readiness for clinical application as part of horizon scanning.