Thymic neoplasms: an update on the use of chemotherapy and new targeted therapies. A literature review

Immunotherapy of thymic epithelial tumors: molecular understandings and clinical perspectives

Immunotherapy has emerged to play a rapidly expanding role in the treatment of cancers. Currently, many clinical trials of therapeutic agents are on ongoing with majority of immune checkpoint inhibitors (ICIs) especially programmed death receptor 1 (PD-1) and its ligand 1 (PD-L1) inhibitors. PD-1 and PD-L1, two main immune checkpoints, are expressed at high levels in thymic epithelial tumors (TETs) and could be predictors of the progression and immunotherapeutic efficacy of TETs. However, despite inspiring efficacy reported in clinical trials and clinical practice, significantly higher incidence of immune-related adverse events (irAEs) than other tumors bring challenges to the administration of ICIs in TETs. To develop safe and effective immunotherapeutic patterns in TETs, understanding the clinical properties of patients, the cellular and molecular mechanisms of immunotherapy and irAEs occurrence are crucial. In this review, the progress of both basic and clinical research on immune checkpoints in TETs, the evidence of therapeutic efficacy and irAEs based on PD-1 /PD-L1 inhibitors in TETs treatment are discussed. Additionally, we highlighted the possible mechanisms underlying irAEs, prevention and management strategies, the insufficiency of current research and some worthy research insights. High PD-1/PD-L1 expression in TETs provides a rationale for ICI use. Completed clinical trials have shown an encouraging efficacy of ICIs, despite the high rate of irAEs. A deeper mechanism understanding at molecular level how ICIs function in TETs and why irAEs occur will help maximize the immunotherapeutic efficacy while minimizing irAEs risks in TET treatment to improve patient prognosis.

Efficacy and safety of treatments for advanced thymic carcinoma after failure of first-line platinum-based chemotherapy: A systematic literature review and meta-analysis

Thymic carcinoma (TC) is a rare cancer and patients failing initial chemotherapy (relapse/refractory) face limited therapeutic options given no approved options or consensus standard of care. This study aimed to identify and summarize clinical outcomes of all regimens evaluated in clinical trials of relapsed or refractory patients. Interventional trials enrolling advanced TC patients who failed first-line chemotherapy and reported outcomes in this group were eligible for inclusion in our systemic literature review (SLR). Between-study heterogeneity was assessed to determine the feasibility of pooling specific studies and treatments. Objective response rate (ORR), overall survival (OS), progression-free survival (PFS), and duration of response (DOR) endpoints were of interest for meta-analysis. Nineteen trials were identified in the SLR. Three trials with one or two TC patients were removed from our assessment to reduce publication bias. Response rates among studies with at least ten TC patients varied from 9 % to 38 %. Pooled ORRs in patients receiving S-1 (46 patients), sunitinib (46 patients), or pembrolizumab (66 patients) were 28 %, 24 %, and 21 %, respectively. Prolonged duration of response with pembrolizumab was observed with a pooled median of 23.8 months (95 % confidence interval [CI]: 12, not reached). Median PFS of five months or greater was reported in patients treated with sunitinib, lenvatinib, pembrolizumab, capecitabine + gemcitabine, everolimus, or S-1. Median OS of 20 months or greater was reported in trials evaluating S-1 or pembrolizumab; this endpoint was not reached in trials evaluating lenvatinib, regorafenib, or sunitinib. Generalizability of treatment effects is challenging in the research of rare diseases and meta-analysis of clinical outcomes may help to increase precision and relevance of results to the larger TC population. Our study found limited treatment options upon relapse, demonstrating a need for further investigations into novel therapeutics and well-powered clinical trials to better inform on optimal treatments.

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.

Stage-related outcome for thymic epithelial tumours

BACKGROUND

Thymic epithelial tumours (TETs) are characterized by a wide variety of biological behaviors. Radical resection and stage are strong prognostic factors. Aim of this study is to review our Single Center Experience.

METHODS

One hundred and seventy-seven patients observed in the period from January 2000 to December 2016 were included in the study. Data regarding clinicopathologic features, treatment, and survival were collected. Stage-related clinical standpoints and therapeutic options were also evaluated.

RESULTS

Non-surgical treatment was primarily performed in 15 (8.47%), unresectable disease was intraoperatively found in 12 cases (7.4%). The analysis of 150 patients undergoing curative surgery revealed 70 stage I TET (46.66%), 49 stage II (32.66%), 19 stage III (12.66%), 6 stage IVa (4%) and 6 stage IVb (4%) at the first hospital admission. Histology identified 12 A thymoma (8%), 38 AB (25.33%), 24 B1 (16%), 50 B2 (33.33%), 19 B3 (12.66%) and 7 carcinomas (4.66%). The mean follow up time was 84.14 months (sd = 61.68 months). Disease relapse occurred in 13 patients (8.78%) at a mean period of 78.85 months (sd = 60.87 months) after surgery. Exitus due to thymoma happened in 6 cases (4.05%) after a mean survival of 56.02 months (sd = 25.17 months). The 5-year overall survival rate was 0.94 (95%CI 0.88-0.97) and the 5-year disease-free survival rate was 0.90 (95%CI 0.83-0.94). The 5-year overall survival rates were 96.1% (95% CI, 89.9-98.5%) for the early stages and 87.4% (95% CI, 65.6-95.8%) for the advanced stages (p = 0.670). The 5-year disease-free survival rates resulted being 98.8% (95% CI, 92.3-99.8%) for the early stages and 59.8% (95% CI, 37.8-76.2%) for the advanced stages (p < 0.001).

CONCLUSIONS

Advanced stage TETs are characterized by higher mortality and recurrence rates. Although technically demanding, surgery, as part of multimodality therapy, could prolong survival. Iterative surgical treatment of recurrences is a viable option for selected patients.

TRIAL REGISTRATION

The study was approved by the Institutional Review Board of Perugia and Terni University Hospitals [Code T1003] and was retrospectively registered.

Carbonic anhydrase 9 expression is associated with poor prognosis, tumor proliferation, and radiosensitivity of thymic carcinomas

Introduction

Thymic epithelial tumors (TETs) comprise several histologies of thymoma and thymic carcinomas (TCs), and TC frequently metastasizes and causes death. We therefore aimed here to identify key molecules closely related to prognosis and their biological roles in high-risk TETs, particularly TCs.

Results

RNA sequence analysis demonstrated that hypoxia-related genes were highly expressed in TETs. The expression of the hypoxia-related gene CA9 was noteworthy, particularly in TCs. Immunohistochemical analysis revealed that CA9 was expressed in 81.0% of TCs and 20.7% of all TET samples. CA9 expression was significantly associated with Masaoka stage, WHO classification, and recurrence-free survival after tumor resection (P = 0.005). The down-regulation of CA9 transcription in TC cell lines by small interfering RNAs significantly inhibited CA9 expression, which inhibited proliferation and increased sensitivity to irradiation.

Conclusions

CA9 expression may serve as a significant prognostic marker of TETs and therefore represents a potential target for the development of novel drugs and radiation-sensitizing therapy designed to improve the outcomes of patients with TCs.

Materials and Methods

We performed comprehensive transcriptome sequencing of 23 TETs and physiologic thymic specimens to identify genes highly and specifically expressed in high-risk TETs, particulary TCs. We performed immunohistochemical analysis of 179 consecutive surgically resected TETs to evaluate the significance of the association of protein expression with clinicopathological features and prognosis. The biological significance of the most promising prognostic marker was further studied using the TC cell lines, Ty-82 and MP57.

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.

High CTLA-4 expression correlates with poor prognosis in thymoma patients

Thymomas, tumors that arise from epithelial cells of the thymus gland, are the most common neoplasms of the anterior mediastinum, with an incidence rate of approximately 2.5 per million/year. Cytotoxic T Lymphocyte Antigen 4 (CTLA-4 or CD152) exerts inhibitory activity on T cells, and since its oncogenic role in the progression of different types of tumors, it has emerged as a potential therapeutic target in cancer patients. In this study, we assessed the expression of CTLA-4 both at mRNA and protein levels in paraffin embedded-tissues from patients with thymomas. Furthermore, we evaluated the relationship between CTLA-4 expression and the clinical-pathologic characteristics and prognosis in patients with thymomas. Sixty-eight patients with median age corresponding to 62 years were included in this analysis. Thymomas were classified accordingly to the WHO and Masaoka-Koga for histochemical analysis and for prognostic significance. A statistical difference was found between CTLA-4 mRNA levels in human normal thymus compared with thymoma specimens. CTLA-4 expression was statistically found to progressively increase in A, B1, B2, AB and it was maximal in B3 thymomas. According to Masaoka-Koga pathological classification, CTLA-4 expression was lower in I, IIA and IIB, and higher in invasive III and IV stages. By confocal microscopy analysis we identified the expression of CTLA-4 both in tumor cells and in CD45+ tumor-infiltrating leukocytes, mainly in B3 and AB thymomas. Finally, CTLA-4 overexpression significantly correlates with reduced overall survival in thymoma patients and in atypical thymoma subgroup, suggesting that it represents a negative prognostic factor.

Postoperative Radiotherapy in Locally Invasive Malignancies of the Thymus: Patterns of Care and Survival

INTRODUCTION

Our purpose was to determine the overall survival (OS) benefit of postoperative radiotherapy (PORT) in patients with advanced thymic malignancies and the associated predictors of PORT receipt.

METHODS

We queried the National Cancer Data Base for all stage II to III thymic malignancies. Trends in PORT use over time were analyzed using least squares linear regression. Factors predictive of PORT and OS were identified by using multivariate logistic and Cox regression analysis, respectively.

RESULTS

We identified 1156 patients between 2004 and 2012 who met the inclusion criteria. The utilization of PORT was found to increase over the study period by 41% (37% to 52% [p = 0.01]). On multivariate analysis, the factors found to be the most predictive of receipt of PORT were positive surgical margins (adjusted OR = 1.98 [p < 0.01]) and treatment at a nonacademic facility (adjusted OR = 1.44 [p = 0.01]). The 5-year OS was superior for patients receiving PORT compared with for those who did not (83% versus 79%, p = 0.03). Receipt of PORT was associated with a trend toward decreased risk for death on multivariate analysis (hazard ratio = 0.75 [p = 0.09]). In addition, a positive macroscopic margin was the most important predictor of survival (hazard ratio = 3.48 [p < 0.01]). On subgroup analysis, patients with thymic carcinoma and WHO histologic types A and AB were associated with an OS benefit with PORT, whereas types B1, B2, and B3 were not. Patients with positive margins were not associated with an OS benefit with PORT.

CONCLUSIONS

The use of PORT in patients with advanced thymic malignancies is increasing over time and is determined by both clinical and demographic factors. Receipt of PORT was associated with improved OS. The OS benefit with PORT was dependent on the WHO histologic type.

New findings on thymic epithelial tumors: Something is changing

Thymic epithelial tumors (TETs) are uncommon neoplasms with a wide range of anatomical, clinical, histological and molecular malignant entities. To date the management of TETs within clinical practice is based on a multimodal therapeutic strategy including surgery, chemotherapy and radiotherapy with a multidisciplinary approach and prognostic evaluation is mainly based on Masaoka staging and World Health Organization classification. Therefore novel strategies are needed, especially for refractory and/or recurrent TETs and for thymic carcinomas that present a poor prognosis. Personalized approaches are currely being developed and molecular targets are emerging from recent integrated genomic analyses. Targeted therapy will represent an important treatment option for TETs with an aggressive histology. To date, data indicate that vascular endothelial growth factor molecules, insulin-like growth factor 1 receptor, cyclin-dependent kinases and mammalian target of rapamycin may be potentially useful as targeted biological therapies.

Thymic carcinoma patients with myasthenia gravis exhibit better prognoses

BACKGROUND

Thymic carcinoma is an aggressive mediastinal neoplasm with a poor prognosis, but the factors that contribute to its prognosis are not completely understood. Myasthenia gravis (MG) can coexist with thymic carcinoma with low incidence, but the effect MG has on thymic carcinoma prognosis is unknown. Here, we investigated the prognostic factors of thymic carcinoma and the influence of MG on patients with this disease.

METHODS

Between January 1996 and December 2012, 49 patients were diagnosed with thymic carcinoma and surgically treated at our institution. Clinical data and survival information were recorded and systematically reviewed. Kaplan-Meier survival curves were generated, and independent prognostic factors were identified by Cox's proportional hazard model.

RESULTS

Complete resection was achieved in 30 patients (61.2 %), and incomplete resection was performed on the other 19 patients (38.8 %). Six of the 49 patients with thymic carcinoma also presented with MG (12.2 %). Interestingly, these 6 patients exhibited much better prognoses when compared to the other 43 patients. Patients with MG also had significantly smaller tumors (P = 0.045), earlier Masaoka stage (P = 0.048), and higher complete resection rates (P = 0.042). However, multivariate analysis demonstrated that complete resection was the only independent predictor for overall survival (OS) (P < 0.001).

CONCLUSIONS

The OS of patients with thymic carcinoma depends on complete resection, but patients with MG also demonstrate improved prognoses. MG patients have higher rates of complete surgical resection, which may account for their better prognoses. Patients with MG have unique features that may aid in the clinical management of these patients.

Thymic cancer mimicking a metastasis of testicular seminoma

A 48-year-old man presented with a left testicular mass. Computed tomography showed an anterior mediastinal tumor, with positive uptake in positron emission tomography images. Radical orchiectomy was performed; the histology was seminoma. Thus, a diagnosis of testicular seminoma with thymic metastasis (stage III) was made and he underwent four courses of bleomycin, etoposide and cisplatin chemotherapy. The tumor shrank from 2.5 to 1.4 cm, but grew to 1.9 cm 1 month after the fourth course. He underwent two courses of paclitaxel, ifosfamide and cisplatin chemotherapy, followed by the resection of mediastinal tumor, the histopathological diagnosis of which was thymic cancer. Adjuvant radiation therapy was administered and no recurrences were evident at 1 year postoperatively. This is the first reported case of thymic cancer coexisting with stage I testicular seminoma.