Sunitinib in patients with advanced thymic malignancies: Cohort from the French RYTHMIC network

Autoimmunity in thymic epithelial tumors: a not yet clarified pathologic paradigm associated with several unmet clinical needs

Thymic epithelial tumors (TETs) are rare mediastinal cancers originating from the thymus, classified in two main histotypes: thymoma and thymic carcinoma (TC). TETs affect a primary lymphoid organ playing a critical role in keeping T-cell homeostasis and ensuring an adequate immunological tolerance against "self". In particular, thymomas and not TC are frequently associated with autoimmune diseases (ADs), with Myasthenia Gravis being the most common AD present in 30% of patients with thymoma. This comorbidity, in addition to negatively affecting the quality and duration of patients' life, reduces the spectrum of the available therapeutic options. Indeed, the presence of autoimmunity represents an exclusion criteria for the administration of the newest immunotherapeutic treatments with checkpoint inhibitors. The pathophysiological correlation between TETs and autoimmunity remains a mystery. Several studies have demonstrated the presence of a residual and active thymopoiesis in adult patients affected by thymomas, especially in mixed and lymphocytic-rich thymomas, currently known as type AB and B thymomas. The aim of this review is to provide the state of art in regard to the histological features of the different TET histotype, to the role of the different immune cells infiltrating tumor microenvironments and their impact in the break of central immunologic thymic tolerance in thymomas. We discuss here both cellular and molecular immunologic mechanisms inducing the onset of autoimmunity in TETs, limiting the portfolio of therapeutic strategies against TETs and greatly impacting the prognosis of associated autoimmune diseases.

An Overview of the Use of Anti-Angiogenic Agents in the Treatment of Thymic Epithelial Tumors

Angiogenesis significantly influences the carcinogenesis of thymic epithelial tumors (TET). Both thymomas and thymic carcinoma (TC) overexpress VEGF-A and VEGFR-1 and -2. This review aims to provide an appraisal of the use of anti-angiogenics in the treatment of TET. The literature research identified 16 studies that were deemed eligible for further analysis. Seven studies assessed the clinical efficacy of sunitinib and five studies the use of apatinib and/or anlotinib. The multicenter Japanese phase II REMORA trial investigated the efficacy of lenvatinib, which is a multi-targeted inhibitor of VEGFR, FGFR, RET, c-Kit, and other kinases. The objective response rate was 38% (25.6-52%), which is the highest documented in TET that progressed after first-line chemotherapy. Anti-angiogenic agents may be useful in the treatment of TET, which are not amenable to curative treatment. Their toxicity profile seems to be acceptable. However, angiogenesis inhibitors do not appear to have a major influence on either thymomas or TC, although multikinase inhibitors may have some effect on TC. The current evidence suggests that the most active agent is lenvatinib, whereas sunitinib could be proposed as an acceptable second-line therapy for TC. Further research concerning the combination of immune checkpoint inhibitors with anti-angiogenic drugs is warranted.

Immunotherapy and Targeted Therapies Efficacy in Thymic Epithelial Tumors: A Systematic Review

BACKGROUND

Thymic epithelial tumors (TET) are rare neoplasms of the anterior mediastinum. Surgery is the mainstay treatment for resectable TET, whereas systemic treatments are reserved for unresectable and metastatic tumors. The development of new treatments, such as immune checkpoint inhibitors (ICI) and targeted therapies, with promising results in other types of solid tumors, has led to the investigation of their potential efficacy in TET. The study of tumor microenvironments (TME) is another field of investigation that has gained the interest of researchers. Taking into account the complex structure of the thymus and its function in the development of immunity, researchers have focused on TME elements that could predict ICI efficacy.

MATERIALS AND METHODS

The primary objective of this systematic review was to investigate the efficacy of ICI in TET. Secondary objectives included the toxicity of ICI, the efficacy of targeted therapies in TET, and the evaluation of the elements of TME that may be predictive factors of ICI efficacy. A literature search was conducted in February 2023 using the Ovid Medline and SciVerse Scopus databases.

RESULTS

2944 abstracts were retrieved, of which 31 were retained for the systematic review. Five phase II and one retrospective study assessed ICI efficacy. The overall response rate (ORR) varied from 0% to 34%. Median progression-free survival (PFS) ranged from 3.8 to 8.6 months, being lower in thymic carcinoma (TC) (3.8-4.2 months). Median overall survival (OS) ranged from 14.1 to 35.4 months. Treatment-related adverse events occurred in 6.6% to 27.3% of patients. Sixteen studies assessed targeted therapies. The most active molecule was lenvatinib, with 38% ORR in patients with TC while no activity was detected for imatinib, erlotinib plus bevacizumab, and saracatinib. Ten studies assessed TME elements that could predict ICI efficacy. Four studies focused on the tumor-infiltrating immune cells suggesting improved outcomes in patients with TC and high tumor-infiltrating lymphocyte densities. Another study showed that CD8+, CD20+, and CD204+ tumor-infiltrating immune cells in cancer stroma might be prognostic biomarkers in TC. Another study identified the immune-related long non-coding RNAs as a predictor of response to ICI. Tumor mutational burden was identified as a predictive factor of ICI efficacy in one study.

CONCLUSIONS

Despite study heterogeneity, this review shows that ICI could be a therapeutic option for selected patients with TET that are not amenable to curative radical treatment after first-line chemotherapy.

Current Treatment Approaches for Thymic Epithelial Tumors

Thymic epithelial tumors (TETs), including thymoma, thymic carcinoma and neuroendocrine tumors, are uncommon tumors that originate from the epithelial cells of the thymus. Nevertheless, despite their rarity, they represent the most common tumor type located in the anterior mediastinum. Therapeutic choices based on staging and histology may include surgery with or without neoadjuvant or adjuvant therapy represented by chemotherapy, radiotherapy or chemo-radiotherapy. For patients with advanced or metastatic TETs, platinum-based chemotherapy remains the standard first-line treatment; however, some new drugs and combinations are currently under evaluation. In any case, proper management of patients with TETs requires a multidisciplinary team approach to personalize care for each patient.

Thymic Epithelial Tumors: An Evolving Field

Despite their rarity, thymic epithelial tumors (TETs) have attracted much interest over the years, leading to an impressive number of histological and staging classifications. At present, TETs are divided by the WHO classification into four main subtypes: type A, type AB, and type B thymomas (subdivided into B1, B2, and B3), and thymic carcinomas, going from the more indolent to the most aggressive ones. Among many debated staging proposals, the TNM and the Masaoka-Koga staging systems have been widely accepted and used in routine practice. The four-tiered histological classification is symmetrically mirrored by the molecular subgrouping of TETs, which identifies an A-like and an AB-like cluster, with frequent GTF2I and HRAS mutations; an intermediate B-like cluster, with a T-cell signaling profile; and a carcinoma-like cluster comprising thymic carcinomas with frequent CDKN2A and TP53 alterations and a high tumor molecular burden. Molecular investigations have opened the way to tailored therapies, such as tyrosine kinase inhibitors targeting KIT, mTOR, and VEGFR, and immune-checkpoints that have been adopted as second-line systemic treatments. In this review, we discuss the crucial events that led to the current understanding of TETs, while disclosing the next steps in this intriguing field.

Emerging therapies in thymic epithelial tumors (Review)

Thymic epithelial tumors (TETs), including thymomas and thymic carcinomas, are rare malignancies arising from the thymus gland. The optimal management requires a multidisciplinary approach. Standard first-line systemic treatment involves cytotoxic chemotherapeutic regimens; however, alternative options for systemic treatment are required. Current research focuses on the unique profile of immune-related pathogenic mechanisms of TETs, involving an overlap with certain autoimmune phenotypes, as well as on determining the landscape of oncogenic molecular alterations and the role of tumor angiogenesis. The aim of the present review is to summarize the current clinical investigation on immunotherapy and targeted agents in the management of TETs. Regarding immune checkpoint inhibitors, efficacy results are promising in certain subsets of patients; however, caution is required concerning their toxicity. Anti-angiogenic agents, mainly potent small-molecule inhibitors, have demonstrated antitumor activity in TETs, whereas other targeted agents, including KIT inhibitors and epigenetic agents, are associated with encouraging, yet still modest results for unselected populations, in the absence of predictive biomarkers. Future research should focus on identifying predictive biomarkers for patients with TETs, and should implement multicenter collaborations and appropriate clinical trials tailored for rare tumor types.

The efficacy of small molecule anti-angiogenic drugs in previously treated Thymic carcinoma

BACKGROUND

Antiangiogenic drugs have shown initial efficacy in the treatment of advanced thymic carcinomas (TCs); however, data are limited. In this study, we provide real-world data relating to the efficacy of antiangiogenic drugs for the treatment of patients with TCs.

METHODS

We retrospectively collected data on clinical progress after first-line chemotherapy in TCs patients who were treated with small molecule antiangiogenic drugs at our institution between January 2010 and December 2021. Tumor response was evaluated according to version 1.1 of the Response Evaluation Criteria in Solid Tumors. Progression free survival and overall survival were calculated using the Kaplan-Meier method.

RESULTS

Of the 17 patients enrolled, 13 (76.5%) received apatinib and four (23.5%) anlotinib monotherapy with an objective response rate of 23.5%. Eleven (64.7%) patients had stable disease. The median follow-up period was 46.0 months (95% confidence interval [CI], 33.0-59.0 months). The median progression survival and overall survival were 7.9 months (95% CI, 6.5-9.3) and 47.0 months (95% CI, 35.4-58.6), respectively. In the 13 patients receiving apatinib, the median PFS was 7.0 months (95% CI, 5.0-9.0), compared with 8.0 months (95% CI, 2.7-13.3 months) for patients in the anlotinib group (P = 0.945). The most common grade 3 adverse events (AEs) were hypertension (n = 3, 23.1%), followed by proteinuria and hand-foot syndrome (HFS, n = 2, 15.4%). There were no grade 4 AEs although eight patients (47.1%) required mid-course discontinuation.

CONCLUSION

For refractory TCs, small molecule antiangiogenic drugs are efficacious as second- or post-line treatments. The toxicity of antiangiogenic therapy is manageable.

Continuous sunitinib schedule in advanced platinum refractory thymic epithelial neoplasms: A retrospective analysis from the ThYmic MalignanciEs (TYME) Italian collaborative group

BACKGROUND

Thymic epithelial tumors (TETs) are rare diseases, with diverse clinical behaviour and prognosis. Intermittent dosing sunitinib represents the gold-standard systemic treatment following platinum-based chemotherapy. To ensure more homogeneous drug exposure, continuous daily dosing (CDD) sunitinib is utilised in other malignancies; however, no data exist in patients with TETs.

METHODS

We retrospectively examined data from patients with platinum-resistant TETs receiving CDD sunitinib 37.5 mg between 1 May 2017 and 31 May 2022 within the Italian collaborative group for ThYmic MalignanciEs. Primary end-points were median progression-free survival, overall response rate (ORR), median duration of response and major treatment-related adverse events.

RESULTS

A total of 20 consecutive patients (12 thymic carcinoma [TC], 6 B3, and 2 B2 thymoma) were evaluated. Among the 19 patients evaluable for response, ORR was 31.6% (95% CI, 12.5%-56.5%). Among patients with TC, one complete response, four partial responses, and four stable diseases were observed (ORR 41%).The overall median progression-free survival was 7.3 months (95% CI, 4.5-10.3): 7.3 months (95% CI, 4.4-NA) within patients with thymoma and 6.8 months (95% CI, 2.8-10.3) in patients with TC; median duration of response was 10.3 months (95% CI, 2.8-NA). CDD was associated with a manageable toxicity profile. Six patients (30%) experienced >G2 toxicity, nine required dose reduction and three discontinued treatment due to adverse events.

CONCLUSIONS

CDD sunitinib showed a relevant antitumor activity and confirmed a good toxicity profile. Similar effectiveness and a better toxicity profile as compared with intermittent dosing historical data suggest that this schedule should be considered.

Investigational drugs for the treatment of thymic cancer: a focus on phase 1 and 2 clinical trials

INTRODUCTION

Thymic epithelial tumors (TETs) are rare tumors of thymic epithelial cells. Treatment options for advanced disease patients who failed standard platinum-based chemotherapy are limited.

AREAS COVERED

Phase I and II trials published in the last five years testing new systemic treatments for advanced TET patients are discussed, as well as ongoing trials. A PubMed database literature review was conducted for articles published between January 2016 and December 2021, and ongoing clinical trials were retrieved from ClinicalTrials.gov database.

EXPERT OPINION

The most promising classes of new drugs in TET patients are angiogenesis inhibitors and immune checkpoint antibodies (ICIs). Sunitinib and Lenvatinib showed response rates of 26% and 38%, respectively, and ICIs showed durable responses in 20-25% in thymic carcinoma patients (TCs). Both approaches are mainly active in TCs, therefore new treatment options for thymomas is an unmet medical need.Two major new therapeutic strategies are ICIs combinations with other drugs and drugs that target pathways that are dysregulated in TETs.Future challenges include the development of preclinical models to help identify novel targets and test new treatment strategies, and randomized clinical trials to provide reliable evidence based on survival endpoints.

Therapeutic options in thymomas and thymic carcinomas

INTRODUCTION

Radical surgery is the best therapeutic option for thymic malignancies. However, patients with advanced or recurrent thymic malignancies often require chemotherapy or radiotherapy. Since thymic malignancies are rare cancers, the efficacy and safety of treatments have been verified based on small Phase 2 trials or retrospective studies.

AREA COVERED

We comprehensively reviewed the treatment strategies for thymic malignancies, including surgery, radiotherapy, and pharmacotherapy, including cytotoxic chemotherapy, molecular-targeted therapy, and immunotherapy. Additionally, we reviewed specific situations, such as pleural dissemination, central nervous system metastasis, and paraneoplastic syndrome.

EXPERT OPINION

Cytotoxic chemotherapy remains the standard option in pharmacotherapy. However, multikinase inhibitors, such as sunitinib and lenvatinib, and immune checkpoint inhibitors including pembrolizumab have been developed to treat thymic carcinomas. Now, a Phase 2 study is evaluating whether lenvatinib plus pembrolizumab benefits patients with type B3 thymoma or thymic carcinoma. Phosphatidylinositol 3-kinase/AKT/ mammalian target of rapamycin inhibitors may contribute to disease control and octreotide scan is only applicable to somatostatin analogues. Although the genomic characteristics of thymic malignancies have been analyzed, few actionable mutations have been detected in general. The development of a treatment strategy using combination pharmacotherapy is anticipated.

The Use of Sunitinib as Maintenance Therapy in a Pediatric Patient With a Poorly Differentiated Thymic Carcinoma

BACKGROUND

Thymic carcinomas are rare aggressive mediastinal tumors with a median survival of 2 years.

OBSERVATION

We present a pediatric patient who was diagnosed with metastatic thymic carcinoma and showed continuous improvement of his primary mass and lung metastases with a regimen of cisplatin/docetaxel followed by long-term maintenance therapy with sunitinib for over 5 years.

CONCLUSIONS

This report demonstrates a long-term positive treatment effect using chemotherapy followed by sunitinib in an advanced thymic carcinoma. We are not aware of other reports of pediatric patients with metastatic thymic carcinoma treated with sunitinib maintenance who maintained a durable response for this prolonged period of time.

The Never-Ending History of Octreotide in Thymic Tumors: A Vintage or A Contemporary Drug?

Simple Summary

Thymic epithelial tumors are rare tumors frequently associated with paraneoplastic syndromes, the most common being myasthenia gravis and pure red cell aplasia. While patients with limited-stage cancer can often undergo resolutive surgery, advanced surgically unresectable and metastatic tumors can be refractory to first-line platinum-based treatment and represent a medical challenge. Somatostatin receptor expression was documented in thymic tumors both in vivo and in vitro and represents the rationale for therapeutic use. Despite single-case reports and three single-arm phase II studies, as well as the inclusion of somatostatin analogs in National Comprehensive Cancer Network guidelines, the role of these drugs in thymic epithelial tumors is still rather undefined.

Abstract

Thymic epithelial tumors are rare tumors usually presenting as a mass located in the anterior mediastinum and/or with symptoms deriving from associated paraneoplastic syndromes. Unresectable platinum-refractory tumors are often treated with alternative regimens, including chemotherapeutic agents as well as chemo-free regimens. The most popular unconventional therapy is represented by the somatostatin analog octreotide, which can be used alone or with prednisone. The in vivo expression of somatostatin receptors documented by imaging with indium-labeled octreotide or gallium-68 Dotapeptides, the successful use of octreotide and prednisone in a chemo-refractory patient, and, thereafter, the experiences from a case series have enforced the idea that this treatment merits consideration—as proved by its inclusion in the National Comprehensive Cancer Network guidelines. In the present review, we analyze the preclinical basis for the therapeutic use of somatostatin and prednisone in refractory thymic tumors and discuss the available studies looking at future perspectives.

Thymic tumours and their special features

Thymic tumours are rare thoracic malignancies, that may be aggressive and difficult to treat. The pillars of the management include pathological review, consideration of differential diagnoses, staging and multidisciplinary discussion. Assessment of resectability is key to drive the treatment sequencing. Association with autoimmune diseases, especially myasthenia gravis, is observed, which impacts the oncological management. Networks are being built at the national and international levels. This article provides an overview of the most recent findings in the diagnosis, staging, histology, and management strategies of thymic tumours.

Thymic tumours are rare and heterogeneous tumours. Management is based on multidisciplinary discussion and networking.https://bit.ly/3kYAZ7u

Salvage Chemotherapy in Patients with Previously Treated Thymic Carcinoma

Thymic carcinoma is a rare neoplasm, and it is difficult to achieve complete remission with systemic chemotherapy. In advanced or recurrent thymic carcinoma, platinum-based chemotherapy is chosen as the first-line setting; however, it remains unclear which regimen is better to improve its outcome. It remains unknown whether salvage chemotherapy should be administered to patients with platinum-based chemotherapy-refractory thymic carcinoma. Currently, several clinical studies have investigated the efficacy of second-line settings for advanced thymic carcinoma. As cytotoxic agents, S-1, amrubicin, pemetrexed, docetaxel, paclitaxel, and gemcitabine have been reported as prospective phase II studies or retrospective studies. The overall response rates (ORRs) of S-1, amrubicin, and pemetrexed were 25-50%, 11-44.4%, and 9-10%, respectively. Molecular targeting drugs, such as sunitinib, everolimus, and lenvatinib, also provide clinical effectiveness with tolerability after the failure of platinum-based regimens. Based on the results of the prospective phase II study, the ORR, median progression-free survival, and median overall survival were 16.6% and 5.6 months, respectively, in everolimus, 26% and 7.2 months, respectively, in sunitinib, and 38% and 9.3 months, respectively, in lenvatinib. Although it is difficult to compare each study, lenvatinib appears to be better in increasing efficacy as a second-line setting. However, each study had a small sample size, which may have biased the results of their studies. Further investigation is warranted to elucidate the therapeutic significance of salvage chemotherapy in advanced thymic carcinoma in a large-scale study.

Resound Trial: A phase 2 study of regorafenib in patients with thymoma (type B2-B3) and thymic carcinoma previously treated with chemotherapy

BACKGROUND

Angiogenesis has an important role in thymic epithelial tumors (TETs). Regorafenib inhibits vascular endothelial growth factor receptors (VEGFRs), platelet-derived growth factor receptor β (PDGFR-β), and fibroblast growth factor receptors (FGFRs). This study explored the activity of regorafenib as monotherapy in patients with advanced or recurrent B2-B3 thymoma (T) and thymic carcinoma (TC) previously treated with platinum-containing chemotherapy.

METHODS

A Fleming single-arm, single-stage, phase 2 trial to evaluate the activity of regorafenib (160 mg once a day by mouth for 3 weeks on/1 week off) was planned. The study was designed to reject the null hypothesis of an 8-week progression-free survival (PFS) rate ≤25% with a type I error of 0.10 and a statistical power of 80% at the alternative hypothesis of an 8-week PFS rate of ≥50% (≥8 of 19 evaluable patients progression-free at 2 months).

RESULTS

From June 2016 to November 2017, 19 patients were enrolled (11T/8TC). We observed partial response (PR) in 1 patient (1T) (5.3%), stable disease (SD) in 14 patients (9T/5TC) (73.7%), and progressive disease in 2 patients (1T/1TC) (10.5%), with a disease control rate of 78.9%. According to Choi-criteria, 13 patients (68.4%) achieved PR, and 2 patients SD (10.5%). The median PFS was 9.6 months whereas median overall survival was 33.8 months. The 8-week PFS rate was 78.9% (15 of 19 patients). Grade 3-4 treatment-related adverse events were observed in 10 patients (52.6%).

CONCLUSIONS

The primary end point of this study was reached. The high rate of PR (Choi-criteria) suggests antitumor activity of regorafenib in TETs. On the basis of survival outcomes, the efficacy of regorafenib should be further evaluated in larger studies.

Future Perspective of Chemotherapy and Pharmacotherapy in Thymic Carcinoma

Simple Summary

Thymic carcinoma is a rare cancer, and its biology remains largely unknown. Although complete surgical resection is a standard treatment for thymic carcinoma, systemic chemotherapy is frequently administered in metastatic or recurrent cases. Given the rarity, therapeutic agents are often confirmed on the basis of the results of phase II trials or retrospective studies. Platinum-based combination chemotherapy has long been employed for treating thymic carcinoma. Recently, biomarkers have been explored, and molecular profiles and major oncogenic pathways have gradually been revealed by next-generation sequencing, resulting in the development of targeted therapies. Moreover, clinical trials assessing combination therapy with immune checkpoint inhibitors are ongoing and are expected to be efficacious for treating thymic epithelial tumors. We reviewed the current role of systemic chemotherapy, including targeted therapies and immune checkpoint inhibitors, considering recent findings regarding its biology.

Abstract

Thymic carcinoma is a rare cancer that arises from thymic epithelial cells. Its nature and pathology differ from that of benign thymoma, presenting a poorer prognosis. If surgically resectable, surgery alone or surgery followed by chemoradiotherapy or radiotherapy is recommended by the National Comprehensive Cancer Network Guidelines. Metastatic and refractory thymic carcinomas require systemic pharmacotherapy. Combined carboplatin and paclitaxel, and cisplatin and anthracycline-based regimens have been shown a fair response rate and survival to provide a de facto standard of care when compared with other drugs employed as first-line chemotherapy. Cytotoxic agents have been pivotal for treating thymic carcinoma, as little is known regarding its tumorigenesis. In addition, genetic alterations, including driver mutations, which play an important role in treatments, have not yet been discovered. However, molecular pathways and biomarker studies assessing thymic epithelial tumors have been reported recently, resulting in the development of new agents, such as molecular targeted agents and immune checkpoint inhibitors. As treatment options are currently limited and the prognosis remains poor in metastases and recurrent thymic carcinoma, genetic alterations need to be assessed. In the present review, we focused on the current role of targeted therapies and immune checkpoint inhibitors in treating thymic carcinoma.

Genomic clustering analysis identifies molecular subtypes of thymic epithelial tumors independent of World Health Organization histologic type

Further characterization of thymic epithelial tumors (TETs) is needed. Genomic information from 102 evaluable TETs from The Cancer Genome Atlas (TCGA) dataset and from the IU-TAB-1 cell line (type AB thymoma) underwent clustering analysis to identify molecular subtypes of TETs. Six novel molecular subtypes (TH1-TH6) of TETs from the TCGA were identified, and there was no association with WHO histologic subtype. The IU-TAB-1 cell line clustered into the TH4 molecular subtype and in vitro testing of candidate therapeutics was performed. The IU-TAB-1 cell line was noted to be resistant to everolimus (mTORC1 inhibitor) and sensitive to nelfinavir (AKT1 inhibitor) across the endpoints measured. Sensitivity to nelfinavir was due to the IU-TAB-1 cell line’s gain-of function (GOF) mutation in PIK3CA and amplification of genes observed from array comparative genomic hybridization (aCGH), including AURKA, ERBB2, KIT, PDGFRA and PDGFB, that are known upregulate AKT, while resistance to everolimus was primarily driven by upregulation of downstream signaling of KIT, PDGFRA and PDGFB in the presence of mTORC1 inhibition. We present a novel molecular classification of TETs independent of WHO histologic subtype, which may be used for preclinical validation studies of potential candidate therapeutics of interest for this rare disease.

The role of angiogenetic single-nucleotide polymorphisms in thymic malignancies and thymic benign lesions

Background

We previously showed that selected single-nucleotide-polymorphisms (SNPs) of genes involved in angiogenesis influence the aggressiveness of thymic epithelial tumors (TETs). This study analyzes their role in TETs and in thymic benign lesions, in order to investigate potential correlation with risk and outcome.

Methods

Genomic DNA was extracted from paraffin-embedded tissue of 92 patients, undergoing surgery at our Institution. We investigated by Real-Time PCR the SNPs of the following genes: platelet-derived growth factor receptor-α (PDGFRα), hypoxia-inducible factor-1α (HIF-1α), vascular endothelial growth factor A (VEGF-A), vascular endothelial growth factor receptor-2 and 3 (VEGF-2, VEGFR-3), excision repair cross-complementation group-1 (ERCC1).

Results

Fifty-seven TETs and 35 thymic benign lesions were included into the study. Frequency of SNPs was as follows: rs2057482 C, rs11158358 C and rs11549465 C polymorphisms of HIF1-a: thymomas < general population (P=0.008, P=0.007, and P=0.044 respectively). HIF1-a alleles: general population > study groups, rs1951795C SNP (P=0.026 for benign lesions and P=0.0007 for thymomas), rs10873142T SNP (P=0.008 and P=0.001 respectively), rs12434438 A SNP (P=0.034 and P=0.0007) and rs2301113A SNP (P=0.027 and P=0.010). rs699947C polymorphism of VEGF-A: benign lesions > general population (P=0.012).

Conclusions

This is the first study investigating the angiogenetic polymorphisms in thymic benign lesions and TETs. SNPs analysis may represent a further asset in identification of patients who could benefit from anti-angiogenetic therapy.

Durable efficacy of anlotinib in a patient with advanced thymic squamous cell carcinoma after multiline chemotherapy and apatinib: A case report and literature review

Thymic carcinoma is a rare and highly aggressive mediastinal tumor. Most patients are diagnosed at surgically unresectable stages. Current prospective and retrospective studies have indicated that platinum and anthracycline‐based chemotherapy are the first choice drugs of first‐line therapy for advanced thymic carcinoma. However, there is no optimal treatment after progression for patients who have undergone first‐line and subsequent chemotherapy. Anlotinib, a novel small molecule tyrosine kinase multitarget inhibitor, was approved by the China Food and Drug Administration as a third‐line treatment for advanced non‐small cell lung cancer (NSCLC) in May 2018. Herein we report a case of an advanced thymic squamous cell carcinoma patient harboring EGFR exon 20 insertion who had previously received multiline therapy, including chemotherapy, radiotherapy as well as antiangiogenic therapy. Also as an angiogenesis inhibitor, anotinib had controlled his mediastinal mass after failure of the apatinib treatment. To date, over 23 months of progression‐free survival (PFS) and six years of overall survival (OS) have been achieved. Compared with apatinib, the adverse reactions have been mild and tolerable and the patient's quality of life has improved. To our knowledge, this is the first report where anlotinib has been effective in controlling the progression of thymic carcinoma. In the multiline treatment of advanced thymic carcinoma, anlotinib appears to show great potential when utilized as a salvage treatment.

Everolimus in the treatment of metastatic thymic epithelial tumors

INTRODUCTION

There is emerging evidence to support the use of mTOR inhibitor everolimus in patients with advanced, relapsed-refractory thymic epithelial tumors (TETs). However, patient selection and identifying predictive biomarkers of response remains a challenge. Here, we describe a single-center experience with everolimus in patients with TETs and provide detailed molecular analysis of their thymic tumors.

MATERIALS AND METHODS

Data on all patients with advanced TETs who were prescribed everolimus at Stanford University were retrospectively assessed. Time to treatment failure (TTF) and overall survival (OS) were calculated. STAMP, a 130-gene targeted next generation sequencing (NGS) panel, was performed on each tumor sample.

RESULTS

Twelve patients with thymoma (T) and three with thymic carcinoma (TC) treated with everolimus were included. Patients had been heavily pre-treated with an average of three prior lines of therapy. Three patients discontinued treatment due to adverse events. The average TTF was 14.7 months in T and 2.6 months in TC with median OS of 27.6 months in the entire cohort (NR T and 5.3 months TC). Two patients with paraneoplastic autoimmune diseases had improvement in autoimmunity on everolimus. Pathogenic mutations were observed in 4/15 (27 %) of patients and includedTP53, KEAP1 and CDKN2A. Several variants of unknown significance in key genes responsible for modulating tumor response to mTOR inhibition were also found.

CONCLUSION

As previously reported in a prospective trial, patients with previously treated advanced TETs appear to benefit from everolimus in this single institution cohort. Moreover, there was a manageable toxicity profile and no cases of everolimus-induced pneumonitis. A targeted NGS panel revealed several pathogenic mutations but there was no association between detectable tumor mutations and time to treatment failure in this cohort.

Thymic Malignancy-Updates in Staging and Management

Thymomas are relatively indolent tumors that present with locally advanced disease in 30% of the patients. Thymic carcinoma is a more aggressive histology with shorter disease-free and overall survival. Early-stage tumors are managed best with complete resection. Multimodal therapy is the standard of care for locally advanced tumors and neoadjuvant therapy may help improve respectability. Stage and complete resection are the strongest prognostic factors for long-term survival. Based on early experience, targeted and immunotherapies have shown limited promise in advanced disease.

[Treatment of Recurrent Thymoma]

胸腺瘤是一种具有恶性潜能的疾病，完整切除后的复发率为10%-30%。复发性胸腺瘤的治疗策略及标准未达成一致，治疗方式包括再次手术治疗、化疗、放疗、靶向治疗及免疫治疗等，至今存在着争议。在这篇综述中，通过回顾既往的文献，总结了复发性胸腺瘤的不同治疗方法的适应证、疗效以及预后，以期给复发性胸腺瘤治疗标准的制定提供一些参考。

Immune biomarkers in thymic epithelial tumors: expression patterns, prognostic value and comparison of diagnostic tests for PD-L1

Background

Immunotherapy is currently under investigation in B3 Thymoma (TB3) and Thymic Carcinoma (TC). PD-L1 expression has been evaluated on a limited number of patients with selected antibodies. We aimed to analyze cohort of TB3 and TC with a panel of antibodies to assess the prevalence of PD-L1 expression, its prognostic value and to set up a reproducible test.

Methods

We retrospectively studied 103 patients samples of FFPE histologically confirmed TB3 (n = 53) and TC (n = 50) by expert pathologists within the RYTHMIC national network. We compared PD-L1, PD1, CD8 and PD-L2 expression and performed correlation with tumor types and patients outcomes. Four PD-L1 antibodies were tested, three of them validated as companion tests in lung cancer, one tested on two automates on whole section of tumors. We evaluated the percentage and intensity of both epithelial and immune stained cells.

Results

TB3 epithelial cells had a higher and more diffuse expression of PD-L1 than TC regardless the antibodies tested (p < 0.0001). Three out of four antibodies targeting PD-L1 tested on the DAKO autostainer gave similar staining. Concordance between antibodies was lower for PD-L1 staining on immune cells with no significant difference between TB3 and TC except on E1L3N antibody. PD-L2 antibody stained no tumor epithelial cells. High PD-L1 expression was correlated with a better overall survival for TB3 and was not correlated with tumor staging.

Conclusion

Frequent PD-L1 expression, particularly in TB3, paves the way for immunotherapy in TET (Thymic Epithelial Tumor). Otherwise, we have set up three reproducible LDT (laboratory-developed test) for four PD-L1 antibodies.

Thymic malignancies: emerging systemic therapies

PURPOSE OF REVIEW

The management of thymic malignancies is based on multidisciplinary collaboration. Systemic agents may be administered as an exclusive treatment if local treatment is not achievable. Novel and innovative agents are needed. Integrated genomic analyses reported the activation of targetable signaling pathways in thymomas and thymic carcinomas.

RECENT FINDINGS

Phase II trials reported the antitumor activity of phosphatidylinositol 3-kinase/mechanistic target of rapamycin kinase inhibitors, cyclin dependent kinase inhibitors, and antiangiogenic agents in advanced, refractory thymic malignancies. Meanwhile, a major challenge is the use of immune checkpoint inhibitors, given the frequent association of those tumors with autoimmune disorders.

SUMMARY

Although those innovative agents were assessed in phase II trials reporting on variable antitumor efficacy in terms of response and survival, in selected and limited cohorts of patients, a better understanding of systemic treatment sequences in a real-life setting is mandatory to analyze the actual efficacy of each line of treatment one after another, define the best clinical-pathological selection of patients for the administration of chemotherapy, targeted agents, and immunotherapy, and develop individualized decision-making to optimize the survival of patients with advanced thymic malignancies.

Optimal management of thymic malignancies: current perspectives

Thymic epithelial tumors (TETs) belong to orphan oncology. The incidence of TETs is about 1.3–3.2 cases per million worldwide. Following pathology, evolution and prognosis are variable. The World Health Organization classification distinguishes thymomas and thymic carcinomas. TETs are composed of thymic epithelial tumoral cells and normal lymphocytes. The mean age at diagnosis is 50–60 years-old. There are no identified risk factors. TETs are frequently associated with paraneoplastic syndromes as myasthenia gravis. The complete R₀ surgical resection is the most significant prognosis factor on survival. In 2010, the French National Institute of Cancer labeled the RYTHMIC network as a specific tumor board including thoracic surgeons, oncologist, and radiation therapist to define standard of care for the management of TETs. The aim of the review was to update knowledge to optimize the standard of care.

Systemic treatments for thymoma and thymic carcinoma: A systematic review

Thymic tumours are rare diseases that for most of the cases are cured with surgery and eventually adjuvant radiotherapy. However, about 30% of patients present with advanced stage or relapsing tumours, which require administration of chemotherapy. While cisplatin-adriamycin-cyclophosphamide combination is regularly prescribed, other drugs have been assessed in the literature. Our aim is to evaluate the effectiveness (response rate) of systemic treatments, whatever the therapeutic line, including chemotherapy, targeted therapies and immunotherapies, in thymoma and thymic carcinoma, using the principles of evidence-based medicine. A systematic review was designed using the PICO system, by an experienced librarian and clinicians' experts in thoracic oncology, through the Ovid Medline system. Only phase II-IV trials and retrospective studies including at least 14 patients treated with the same regimen were considered. Articles were independently selected by at least two investigators. Fifty-five eligible articles were retrieved. Sixty% were dealing with platinum-based regimens, mainly cisplatin, and showed overall similar activity (mostly response rate above 50%) independently of the line of treatment or histological type (thymoma versus thymic carcinoma). Non-platinum based regimens included octreotide-prednisone and capecitabine-gemcitabine. Promising data of immunotherapy with antiPDL1 antibody (pembrolizumab) requires confirmation. Based on available data, the most popular and active regimens are cisplatin-anthracycline (CAP or ADOC) or cisplatin-etoposide combinations that should be recommended when considering first-line chemotherapy in thymoma or thymic carcinoma.

RELEVENT Trial: Phase II Trial of Ramucirumab, Carboplatin, and Paclitaxel in Previously Untreated Thymic Carcinoma/B3 Thymoma With Area of Carcinoma

Thymic epithelial tumors are rare malignancies. Thymic carcinoma represents about 20% of all thymic epithelial tumors and has aggressive behavior, with a greater tendency to metastatic spread. Thymic carcinoma is often diagnosed in advanced stages for which systemic treatment is the main therapeutic option. The association of chemotherapy and antiangiogenic agents in the first-line setting has never been investigated in this very rare cancer. However, preclinical and clinical evidence has suggested that inhibition of angiogenesis could be beneficial. The RELEVENT trial is a multicenter, open-label, single-arm, phase II study aimed at investigating the activity and safety of ramucirumab combined with paclitaxel and carboplatin in chemotherapy-naive patients affected by thymic carcinoma or B3 thymoma with area of carcinoma. The primary endpoint of the trial is the overall response rate. Progression-free survival, overall survival, and safety are secondary endpoints. Patient-reported outcomes will be collected at each visit. The mutational status of a subset of genes, polymorphisms, and selected micro-RNA expression will be evaluated.

Systemic Therapy in Advanced Thymic Epithelial Tumors: Insights from the RYTHMIC Prospective Cohort

INTRODUCTION

Thymic epithelial tumors (TETs) are rare malignancies that may be aggressive and difficult to treat. In the advanced setting, systemic treatments may be delivered as primary therapy before surgery or definitive radiotherapy, as exclusive treatment when no focal treatment is feasible, or in the setting of recurrences. Réseau tumeurs THYMIques et Cancer (RYTHMIC) is the nationwide network for TETs in France. The objective of the study was to describe the modalities and analyze the efficacy of systemic treatments for patients with advanced TETs included in the RYTHMIC prospective database hosted by the French Thoracic Cancer Intergroup.

METHODS

All consecutive patients for whom systemic treatment was discussed at the RYTHMIC multidisciplinary tumor board from 2012 to 2015 and who received at least one cycle of treatment were included. The main end points were objective response and progression-free survival (PFS).

RESULTS

A total of 236 patients were included in this analysis. Of those 236 patients, 91 received primary chemotherapy, leading to response rates of 83% for thymomas and 75% for thymic carcinomas and a median PFS of 23.2 months. A strong predictor of longer PFS was histologic type of thymoma (p < 0.001). Exclusive chemotherapy was delivered to 54 patients. The response rates were 31% for thymomas and 37% for thymic carcinomas. The median PFS was 6.2 months, and it was correlated to response rate (p = 0.001). Systemic therapy for a first, second, third, and fourth recurrence was delivered to 114, 81, 51, and 27 patients, respectively. The response rates ranged between 15% and 39% for thymomas and 4% to 21% for thymic carcinomas. The median PFS times were 7.7, 6.2, 5.9, and 6.5 months, respectively.

CONCLUSION

Patients with advanced thymic malignancies may receive multiple lines of systemic therapy, with an opportunity for clinically relevant PFS rates for which objective response may be a surrogate. Our real-life study provides landmark efficacy data that are needed when designing clinical trials to assess innovative agents.

Paraneoplastic immune-mediated neutropenia in a dog following thymoma excision with later development of metastatic thymic carcinoma treated with toceranib phosphate

A thymoma was an incidental finding in a seven-year-old, female neutered, crossbred dog referred for an acute hepatopathy. Excision of the thymoma was performed via median sternotomy, and 11 weeks later the dog presented with severe neutropenia. The bone marrow was hypercellular, and paraneoplastic immune-mediated neutropenia was diagnosed following exclusion of other causes. The neutrophil count increased to normal within seven days of treatment with prednisolone, which was subsequently tapered. A caudal mediastinal mass was documented 17 months following initial thymoma excision, and pleural and mediastinal metastases were evident on CT. Cytology was consistent with carcinoma. Following the prescription of toceranib phosphate, there was stable disease on CT at eight weeks and six months. At 12 months there was severe locoregional progression and the dog died nine days thereafter. Postmortem examination showed diffuse metastatic carcinoma of the caudal mediastinum, parietal pleura and diaphragm, and histopathology/immunohistochemistry was most consistent with thymic carcinoma.

Metastatic Thymic Carcinoma with Long Survival After Treatment with Sunitinib

Thymic carcinomas are the most aggressive histological subtype of thymic tumors with limited data to guide correct management. No standard treatments are available for patients with advanced thymic carcinoma after progressing while on platinum-based chemotherapy. We present a case of a patient with metastatic thymic carcinoma with an unusual response and favorable evolution after receiving treatment with sunitinib, obtaining a progression-free survival of 23 months, much higher than reported to date. We review the literature on the efficacy of sunitinib in metastatic thymic carcinoma after progression to first-line treatment with platinum combinations.

In vitro evaluation of sunitinib loaded bioresorbable microspheres for potential application in arterial chemoembolization

Drug-loadable bioresorbable microspheres (BRMS) are designed for treating hypervascular tumors through chemoembolization, thereby reducing systemic side effects via controllable local delivery. The present study investigated the degradation and loading capability of bioresorbable microspheres with an anti-angiogenic agent, sunitinib, and then evaluated the release profiles in different media (PBS, 10μg/mL and 4mg/mL lysozyme solutions), and tested catheter deliverability as well as potential antiangiogenic effects of the loaded microspheres. The dry weight of the BRMS showed a consistent decrease over the period of incubation in a 10μg/mL lysozyme solution with 61.3% mass remaining on day 21. Sunitinib was loaded efficiently onto the microspheres, with smaller sizes exhibiting a slightly faster loading and release rate. At 2h, the loading percentages were 99.28%, 97.95%, and 94.39% for 100-300, 300-500, and 500-700μm microspheres, respectively. At 8h, the percentage of drug released were 78.4±5.8%, 71.7±0.3%, and 67.0±2.9% for 100-300, 300-500, and 500-700μm microspheres under static medium conditions, respectively. Under replacing-medium conditions, the presence of 10μg/mL lysozyme slightly delayed the drug release while 4mg/mL lysozyme significantly facilitated the drug release from the microspheres as compared with PBS solution. Confocal imaging revealed an even distribution of sunitinib throughout the microspheres. Drug loaded microspheres were delivered through microcatheters smoothly without any clogging. Sunitinib retained its efficacy at reducing the viability of human endothelial cells after elution from the microspheres. Thus, these bioresorbable microspheres are promising for arterial chemoembolization.

Tumor-Associated Macrophages as Target for Antitumor Therapy

It is well known that the microenvironment of solid tumors is rich in inflammatory cells that influence tumor growth and development. Macrophages, called tumor-associated macrophages (TAMs), are the most abundant immune cell population present in tumor tissue. Several studies have demonstrated that the density of TAMs is associated with a poor prognosis and positively correlates with tumor growth. Several studies have proved that TAMs may activate and protect tumor stem cells, stimulate their proliferation as well as promote angiogenesis and metastasis. Furthermore, TAMs-derived cytokines and other proteins, such as CCL-17, CCL-22, TGF-β, IL-10, arginase 1, and galectin-3, make a significant contribution to immunosuppression. Since TAMs influence various aspects of cancer progression, there are many attempts to use them as a target for immunotherapy. The numerous studies have shown that the primary tumor growth and the number of metastatic sites can be significantly decreased by decreasing the population of macrophages in tumor tissue, for example, by blocking recruitment of monocytes or eliminating TAMs already present in the tumor tissue. Moreover, there are attempts at reprogramming TAMs into proinflammatory M1 macrophages or neutralizing the protumoral products of TAMs. Another approach uses TAMs for anticancer drug delivery into the tumor environment. In this review, we would like to summarize the clinical and preclinical trials that were focused on macrophages as a target for anticancer therapies.

Thymic Epithelial Tumors phenotype relies on miR-145-5p epigenetic regulation

BACKGROUND

Thymoma and thymic carcinoma are the most frequent subtypes of thymic epithelial tumors (TETs). A relevant advance in TET management could derive from a deeper molecular characterization of these neoplasms. We previously identified a set of microRNA (miRNAs) differentially expressed in TETs and normal thymic tissues and among the most significantly deregulated we described the down-regulation of miR-145-5p in TET. Here we describe the mRNAs diversely regulated in TETs and analyze the correlation between these and the miRNAs previously identified, focusing in particular on miR-145-5p. Then, we examine the functional role of miR-145-5p in TETs and its epigenetic transcriptional regulation.

METHODS

mRNAs expression profiling of a cohort of fresh frozen TETs and normal tissues was performed by microarray analysis. MiR-145-5p role in TETs was evaluated in vitro, modulating its expression in a Thymic Carcinoma (TC1889) cell line. Epigenetic transcriptional regulation of miR-145-5p was examined by treating the TC1889 cell line with the HDAC inhibitor Valproic Acid (VPA).

RESULTS

Starting from the identification of a 69-gene signature of miR-145-5p putative target mRNAs, whose expression was inversely correlated to that of miR-145-5p, we followed the expression of some of them in vitro upon overexpression of miR-145-5p; we observed that this resulted in the down-regulation of the target genes, impacting on TETs cancerous phenotype. We also found that VPA treatment of TC1889 cells led to miR-145-5p up-regulation and concomitant down-regulation of miR-145-5p target genes and exhibited antitumor effects, as indicated by the induction of cell cycle arrest and by the reduction of cell viability, colony forming ability and migration capability. The importance of miR-145-5p up-regulation mediated by VPA is evidenced by the fact that hampering miR-145-5p activity by a LNA inhibitor reduced the impact of VPA treatment on cell viability and colony forming ability of TET cells. Finally, we observed that VPA was also able to enhance the response of TET cells to cisplatin and erlotinib.

CONCLUSIONS

Altogether our results suggest that the epigenetic regulation of miR-145-5p expression, as well as the modulation of its functional targets, could be relevant players in tumor progression and treatment response in TETs.