Chemotherapy Definitions and Policies for Thymic Malignancies

Survival Outcome After Surgery in Patients With Thymoma Distant Recurrence

OBJECTIVE

The aim of this study is to describe characteristics and survival outcome of patients who underwent surgical treatment for distant thymoma relapse according to the definition of the International Thymic Malignancy Interest Group.

METHODS

Data of patients affected by thymoma recurrence from four different institutions were collected and retrospectively reviewed. Patients with locoregional metastases who underwent nonsurgical therapies and with incomplete data on follow-up were excluded. According to the International Thymic Malignancy Interest Group distant recurrence definition, patients with recurrence due to hematogenic localization were included. Clinical and pathologic characteristics were described using descriptive statistics, whereas survival outcome was calculated using Kaplan-Meier curves and Cox regression analysis.

RESULTS

The analysis was conducted on 40 patients. A single localization was present in 13 patients, the relapse was intrathoracic in 28 cases (70%), and lung involvement was found in 26 cases. The liver was operated in seven cases, whereas other kinds of abdominal involvement were detected in eight cases. Adjuvant treatment was administered in 22 cases (55%).Five- and 10-year overall survival (OS) were 67% and 30%, respectively. Univariable analysis identified as significant favorable factor a low-grade histology (A, B1, B2): five-year OS at 92.3% versus 53.3% in high-grade (B3-C) (p = 0.035). Site of recurrence and number of localization did not influence the prognosis, but in patients with adjuvant therapy administration, there was a survival advantage also if not statistically significant: five-year OS 84.8% versus 54.5% in patients without adjuvant therapy (p = 0.101).Multivariable analysis confirmed as independent prognostic factor low-grade histology: hazard ratio = 0.176, 95% confidence interval 0.042-0.744, p = 0.018.

CONCLUSIONS

Our study revealed a good survival outcome in patients who underwent surgery for distant thymoma recurrence, independently from the number and site of the relapse localization. Patients with A, B1, or B2 histology presented a significantly better survival than patients with B3-C.

Artificial intelligence-powered spatial analysis of tumor-infiltrating lymphocytes as a biomarker in locally advanced unresectable thymic epithelial neoplasm: A single-center, retrospective, longitudinal cohort study

BACKGROUND

Thymic epithelial tumors (TET) are rare malignancies and lack well-defined biomarkers for neoadjuvant therapy. This study aimed to evaluate the clinical utility of artificial intelligence (AI)-powered tumor-infiltrating lymphocyte (TIL) analysis in TET.

METHODS

Patients initially diagnosed with unresectable thymoma or thymic carcinoma who underwent neoadjuvant therapy between January 2004 and December 2021 formed our study population. Hematoxylin and eosin-stained sections from the initial biopsy and surgery were analyzed using an AI-powered spatial TIL analyzer. Intratumoral TIL (iTIL) and stromal TIL (sTIL) were quantified and their immune phenotype (IP) was identified.

RESULTS

Thirty-five patients were included in this study. The proportion of patients with partial response to neoadjuvant therapy was higher in the group with nondesert IP in preneoadjuvant biopsy (63.6% vs. 17.6%, p = 0.038). A significant increase in both iTIL (median 22.18/mm2 vs. 340.69/mm2 , p < 0.001) and sTIL (median 175.19/mm2 vs. 531.02/mm2 , p = 0.004) was observed after neoadjuvant therapy. Patients with higher iTIL (>147/mm2 ) exhibited longer disease-free survival (median, 29 months vs. 12 months, p = 0.009) and overall survival (OS) (median, 62 months vs. 45 months, p = 0.002). Patients with higher sTIL (>232.1/mm2 ) exhibited longer OS (median 62 months vs. 30 months, p = 0.021).

CONCLUSIONS

Nondesert IP in initial biopsy was associated with a better response to neoadjuvant therapy. Increased infiltration of both iTIL and sTIL in surgical specimens were associated with longer OS in patients with TET who underwent resection followed by neoadjuvant therapy.

Risk factor analysis of thymoma resection and its value in guiding clinical treatment

BACKGROUND

In this study, relationships between clinicopathologic characteristics and progression-free survival (PFS) of patients after thymomectomy were analyzed to provide valuable suggestions regarding the treatment of thymoma.

METHODS

Data from 187 thymoma patients undergoing surgery at Beijing Tongren Hospital between January 1, 2006, and December 31, 2015, were retrospectively reviewed. We explored the risk factors for PFS among sex, age, thymoma-associated MG, completeness of resection, histologic type and TNM stage, and investigated their interrelationship.

RESULTS

Among the 187 patients, 18 patients (9.63%) had tumor recurrence/metastasis, and all of whom had in situ recurrence or pleural metastasis, and most of them (10 of 18 patients) had MG symptoms that reappeared or were aggravated. Fifteen patients (8.02%) died, and myasthenic crisis was a leading cause. Based on Cox regression analysis, only age (HR = 3.16; 95% CI: 1.44-6.91; p = 0.004) and the completeness of resection (HR = 9.03; 95% CI: 2.58-31.55; p = 0.001) were independent risk factors for PFS. Furthermore, we found that the completeness of resection was related to the histologic type (p = 0.009) and TNM stage (p < 0.001) by Fisher's exact test.

CONCLUSIONS

The results of this cohort study remind us that we should pay attention to the reappearance or aggravation of MG after thymoma resection, because it is the leading cause of death and may indicate tumor progression. Furthermore, completeness of resection was related to the histologic type and TNM stage, but it was the independent risk factors of thymoma. Therefore, R0 resection is critical to the prognosis of thymoma.

Nomogram based on TNM stage to predict the prognosis of thymic epithelial tumors (TETs) patients undergoing extended thymectomy

Background

Thymomas and thymic carcinoma are thymic epithelial tumors (TETs) of the anterior mediastinum. On the basis of The AJCC 8th Edition of TNM classification, no prognostic prediction model has been established for TETs patients undergoing surgical resection. In this study, based on data from Qilu Hospital of Shandong University, we identified prognostic factors and developed a nomogram to predict the prognosis for TETs patients undergoing extended thymectomy.

Methods

Patients with TETs who underwent thymectomy between 2010 and 2020 were consecutively enrolled. An analysis of multivariate Cox regression and stepwise regression using the Akaike information criterion (AIC) was conducted to identify prognostic factors, and a nomogram for TETs was derived from the results of these analyses. The model was validated internally with the Kaplan-Meier curves, ROC curves and calibration curves.

Results

There were 350 patients with TETs enrolled in the study, and they were divided into a training group (245,0.7) and a validation group (105,0.3). Age, histological type, tumor size, myasthenia gravis, and TNM stage were independent prognostic factors for CSS. The Kaplan-Meier curves showed a significant difference between high nomorisk group and low nomorisk group. A nomogram for CSS was formulated based on the independent prognostic factors and exhibited good discriminative ability as a means of predicting cause-specific mortality, as evidenced by the area under the ROC curves (AUCs) of 3-year, 5-year, and 10-year being 0.946, 0.949, and 0.937, respectively. The calibration curves further revealed excellent consistency between the predicted and actual mortality when using this nomogram.

Conclusion

There are several prognostic factors for TETs. Based on TNM stage and other prognostic factors, the nomogram accurately predicted the 3-, 5-, and 10-year mortality rates of patients with TETs in this study. The nomogram could be used to stratify risk and optimize therapy for individual patients.

Bevacizumab in combination with paclitaxel and platinum for previously treated advanced thymic epithelial tumors

There are no optimal regimens for advanced thymic epithelial tumors (TETs) when frontline chemotherapy fails. In this study, we aimed to assess the activity of Bevacizumab in combination with a routine chemotherapeutic regimen. Patients with advanced TETs who had failed after previous chemotherapy were enrolled in this study. Paclitaxel (160 mg/m²) and cisplatin (70 mg/m²) or carboplatin (area under the curve, 6) plus Bevacizumab (7.5 mg/kg) were intravenously injected on day 1.The treatment was repeated every 3 weeks until the disease progressed or intolerable toxicities occurred. Between March 2018 and August 2020, a total of 49 patients (21 thymoma and 28 thymic carcinoma) received the new treatment. There were 28 men and 21 women with a median age of 50 years (range: 21-73 years). The median number of cycles was 3 (range: 1-6) per patient. The objective response rate (ORR) for all patients was 43% (21/49). The ORRs for thymoma and thymic carcinoma were 24% and 57%, respectively. The median progression-free survival for thymoma and thymic carcinoma was 6 and 8 months, respectively. Hematological toxicities were the main side effects. Paclitaxel and platinum plus Bevacizumab showed promising effects in refractory or relapsed advanced TETs without severe toxicity. Even when applied as salvage therapy, this regimen resulted in a better ORR than frontline chemotherapy.

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

Sphingomonas and Phenylobacterium as Major Microbiota in Thymic Epithelial Tumors

The microbiota has been reported to be closely associated with carcinogenesis and cancer progression. However, its involvement in the pathology of thymoma remains unknown. In this study, we aimed to identify thymoma-specific microbiota using resected thymoma samples. Nineteen thymoma tissue samples were analyzed through polymerase chain reaction amplification and 16S rRNA gene sequencing. The subjects were grouped according to histology, driver mutation status in the GTF2I gene, PD-L1 status, and smoking habits. To identify the taxa composition of each sample, the operational taxonomic units (OTUs) were classified on the effective tags with 97% identity. The Shannon Index of the 97% identity OTUs was calculated to evaluate the alpha diversity. The linear discriminant analysis effect size (LEfSe) method was used to compare the relative abundances of all the bacterial taxa. We identified 107 OTUs in the tumor tissues, which were classified into 26 genera. Sphingomonas and Phenylobacterium were identified as abundant genera in almost all the samples. No significant difference was determined in the alpha diversity within these groups; however, type A thymoma tended to exhibit a higher bacterial diversity than type B thymoma. Through the LEfSe analysis, we identified the following differentially abundant taxa: Bacilli, Firmicutes, and Lactobacillales in type A thymoma; Proteobacteria in type B thymoma; Gammaproteobacteria in tumors harboring the GTF2I mutation; and Alphaproteobacteria in tumors without the GTF2I mutation. In conclusion, Sphingomonas and Phenylobacterium were identified as dominant genera in thymic epithelial tumors. These genera appear to comprise the thymoma-specific microbiota.

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.

Antitumor effect of dimethyl itaconate on thymic carcinoma by targeting LDHA-mTOR axis

AIMS

Thymic carcinoma is a rare type of cancer without an established standard pharmaceutical treatment. This study investigated the antitumor effect of dimethyl itaconate (DI), a cell-permeable derivative of itaconate, on human thymic carcinoma cell line.

MAIN METHODS

Human thymic carcinoma cell line Ty82 was used to evaluate the effect of DI on cell viability. Western blotting and immunohistochemistry were performed to determine the molecular mechanism of antitumor effects of DI on Ty82.

KEY FINDINGS

DI suppressed cell growth and promoted apoptosis of Ty82. The suppressive effect of DI on Ty82 was mediated by the downregulation of lactate dehydrogenase A (LDHA), and the subsequent decrease in the activity of mechanistic target of rapamycin (mTOR). DI exhibited synergistic antitumor effects with a specific inhibitor of large neutral amino acid transporter 1 (LAT1), an amino acid transporter currently being investigated as a novel target for cancer therapy.

SIGNIFICANCE

Our findings demonstrate that DI is a novel potential strategy for thymic carcinoma treatment.

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.

Radiotherapy for thymic epithelial tumours: a review

Thymic epithelial tumours (TETs) represent a rare disease, yet they are the most common tumours of the anterior mediastinum. Due to the rare occurrence of TETs, evidence on optimal treatment is limited. Surgery is the treatment of choice in the management of TETs, while the role of postoperative radiotherapy (PORT) remains unresolved. PORT remains debated for thymomas, especially in completely resected stage II tumours, for which PORT may be more likely to benefit in the presence of aggressive histology (WHO subtype B2, B3) or extensive transcapsular invasion (Masaoka-Koga stage IIB). For stage III thymoma, evidence suggests an overall survival (OS) benefit for PORT after complete resection. For incompletely resected thymomas stage II or higher PORT is recommended. Thymic carcinomas at any stage with positive resection margins should be offered PORT. Radiotherapy plays an important role in the management of unresectable locally advanced TETs. Induction therapy (chemotherapy or chemoradiation) followed by surgery may be useful for locally advanced thymic malignancies initially considered as unresectable. Chemotherapy only is offered in patients with unresectable, metastatic tumours in palliative intent, checkpoint inhibitors may be promising for refractory diseases. Due to the lack of high-level evidence and the importance of a multidisciplinary approach, TETs should be discussed within a multidisciplinary team and the final recommendation should reflect individual patient preferences.

Immunotherapy vs platinum for advanced or metastatic thymic carcinoma: A protocol for systematic review and meta analysis

BACKGROUND

Thymic carcinoma is a rare malignancy, and platinum-based chemotherapy has not previously been established as a standard treatment for advanced or metastatic thymic carcinoma. With the breakthrough and progress of immunotherapy, the possibility of curing thymic carcinoma has greatly increased. Some clinical trials have reported that compared with traditional platinum-based chemotherapy, the use of programmed death 1 and programmed death ligand 1 inhibitors alone can benefit patients and effectively prolong their overall survival. We compare the efficacy of single immunotherapy with traditional platinum-based chemotherapy in a systematic review and meta-analysis to provide a reliable basis for clinicians.

METHODS

Pubmed (Medline), Web of Science, Embase, Cochrane Central Register of Controlled Trials, and Google Scholar will be searched for relevant randomised controlled trials, quasi- randomised controlled trials, and Hi-Q(high quality) prospective cohort trials published or unpublished in any language before March 1, 2021. Subgroup analysis will be performed in tumor pathological stage and ethnicity. INPLASY registration number: INPLASY2020110060.

RESULTS

The results of this study will be published in a peer-reviewed journal.

CONCLUSION

The results of this systematic review and meta-analysis will provide a basis for clinicians to formulate the best chemotherapy regimen for patients, as well as a research clue for clinical researchers in this field. The results of this study will expand the treatment options for thymic carcinoma, but due to the nature of the disease and intervention, large sample clinical trials are not abundant, so we will include some high-quality small sample trials, which may cause high heterogeneity.

INPLASY REGISTRATION NUMBER

INPLASY2020110060.

A Rare Case of a High-Grade Thymic Squamous Cell Carcinoma Presenting as Cardiac Tamponade

Thymic tumors (for example, thymomas, thymic carcinomas, and thymic neuroendocrine tumors) are rare tumors. Thymic carcinomas are aggressive thymic epithelial neoplasms with a poor prognosis. Cardiac tamponade as a presenting complaint of malignant thymic carcinoma is rare.

A 64-year-old woman presented to the emergency department with complaints of progressive exertional dyspnea and chest discomfort. On physical examination, she had diminished breath sounds at the left lung base. The chest x-ray showed a mediastinal widening, significant cardiomegaly, and pleural effusion. CT scan of the chest revealed a dominant mediastinal mass, left-sided pleural effusion, and pericardial effusion. Transthoracic echocardiogram showed 3 cm circumferential pericardial effusion, with evidence of cardiac tamponade. An emergent pericardiocentesis and thoracentesis were done. A core needle biopsy of the mediastinal mass revealed a high-grade non-keratinizing squamous cell thymic carcinoma. Immunohistochemistry staining was positive for pan-cytokeratin, high molecular weight cytokeratin, CK 5/6, E-cadherin, p63, epithelial membrane antigen (EMA), and BerEp4. The patient had repeated hospital admissions due to recurrent malignant pericardial effusion and left pleural effusion. The patient was planned for radiation and chemotherapy with oncology.

In our review of literature, the primary squamous cell thymic carcinoma presenting initially as a cardiac tamponade was found to be a rare event. Early diagnosis and treatment are of utmost importance given the aggressive clinical course culminating in to poor outcome.

Primary Driver Mutations in GTF2I Specific to the Development of Thymomas

Thymomas are rare mediastinal tumors that are difficult to treat and pose a major public health concern. Identifying mutations in target genes is vital for the development of novel therapeutic strategies. Type A thymomas possess a missense mutation in GTF2I (chromosome 7 c.74146970T>A) with high frequency. However, the molecular pathways underlying the tumorigenesis of other thymomas remain to be elucidated. We aimed to detect this missense mutation in GTF2I in other thymoma subtypes (types B). This study involved 22 patients who underwent surgery for thymomas between January 2014 and August 2019. We isolated tumor cells from formalin-fixed paraffin-embedded tissues from the primary lesions using laser-capture microdissection. Subsequently, we performed targeted sequencing to detect mutant GTF2I coupled with molecular barcoding. We used PyClone analysis to determine the fraction of tumor cells harboring mutant GTF2I. We detected the missense mutation (chromosome 7 c.74146970T>A) in GTF2I in 14 thymomas among the 22 samples (64%). This mutation was harbored in many type B thymomas as well as type A and AB thymomas. The allele fraction for the tumors containing the mutations was variable, primarily owing to the coexistence of normal lymphocytes in the tumors, especially in type B thymomas. PyClone analysis revealed a high cellular prevalence of mutant GTF2I in tumor cells. Mutant GTF2I was not detected in other carcinomas (lung, gastric, colorectal, or hepatocellular carcinoma) or lymphomas. In conclusion, the majority of thymomas harbor mutations in GTF2I that can be potentially used as a novel therapeutic target in patients with thymomas.

Lenvatinib in patients with advanced or metastatic thymic carcinoma (REMORA): a multicentre, phase 2 trial

BACKGROUND

Thymic carcinoma is a rare malignant disease and standard treatment for advanced or metastatic thymic carcinoma previously treated with platinum-based chemotherapy has not been established. Lenvatinib is a novel multi-targeted inhibitor of VEGFR, FGFR, RET, c-Kit, and other kinases. The aim of this trial was to assess the activity and safety of lenvatinib as a second-line treatment in thymic carcinoma.

METHODS

This single-arm, phase 2 trial done in eight institutions in Japan (five cancer centres, two medical university hospitals, and one public hospital) enrolled patients with pathologically confirmed unresectable advanced or metastatic thymic carcinoma that progressed following at least one platinum-based chemotherapy. Key inclusion criteria were age 20 years or older, at least one measurable lesion as defined by the Response Evaluation Criteria in Solid Tumors version 1.1, and an Eastern Cooperative Oncology Group performance status of 0 or 1. Patients received 24 mg of lenvatinib orally once daily in 4-week cycles until disease progression or occurrence of unacceptable adverse events. The primary endpoint was objective response rate evaluated at the data cutoff date (Feb 22, 2019), by independent central review in the intention-to-treat population. This trial is registered on JMACCT, JMA-IIA00285, and on UMIN-CTR, UMIN000026777.

FINDINGS

Between April 21, 2017, and Feb 22, 2018, 42 patients were enrolled and all patients were included in the activity and safety analysis. The median follow-up period was 15·5 months (IQR 13·1-17·5). The objective response rate was 38% (90% CI 25·6-52·0, p<0·0001). 16 (38%) of 42 patients had a partial response and 24 (57%) had stable disease. The most frequent grade 3 treatment-related adverse events were hypertension (27 [64%]) and palmar-plantar erythrodysaesthesia syndrome (three [7%]). No patient died from adverse events.

INTERPRETATION

The activity and safety of lenvatinib in patients with advanced or metastatic thymic carcinoma was confirmed. These results suggest that lenvatinib could become a standard treatment option for patients with previously treated advanced or metastatic thymic carcinoma.

FUNDING

Center for Clinical Trials, Japan Medical Association.

CD20+ tumor-infiltrating immune cells and CD204+ M2 macrophages are associated with prognosis in thymic carcinoma

Thymic carcinoma is a rare malignant disease with no standard systemic chemotherapy. The purpose of the present study was to investigate tumor‐infiltrating immune cells (TIIC) in the tumor microenvironment (TME), focusing on the impact of TIIC and program death‐ligand 1 (PD‐L1) expression on clinical outcomes in thymic cancer. Patients with thymic carcinoma resected between 1973 and 2017 were investigated. The tissue specimens were analyzed through immunohistochemical staining to elucidate the prognostic effects of TIIC, their ratios and PD‐L1 in a preliminary cohort (n = 10). The density of TIIC as well as PD‐L1 expression was evaluated in intraepithelial and tumor‐stromal areas on the representative whole section of tumors. The immune factors showing significant association with disease‐free survival (DFS) were evaluated in the total cohort (n = 42). TIIC in the preliminary population showed no significant difference between the two groups. However, CD8, CD20, CD204, FOXP3 and CD20/CD204 ratio demonstrated a tendency to act as predictive markers for recurrence. In the total cohort, significant differences were observed for CD8⁺, CD20⁺ and CD204⁺ cells in tumor islets, and for CD8⁺, CD20⁺ and FOXP3⁺ cells as well as the CD8/CD204 and CD20/CD204 ratios in the stroma, indicating their prognostic effect. The prognostic effect of the PD‐L1 expression in tumor cells could not be established, possibly because of intratumoral heterogeneity. CD8, CD20 and CD204 positive TIIC in stroma were identified as possible better prognostic biomarkers, considering the heterogeneity of other biomarkers. The present study paves the way for exploring strategies of combination immunotherapy targeting B cell immunity in thymic carcinoma.

PD-L1 expression level in different thymoma stages and thymic carcinoma: a meta-analysis

BACKGROUND

The immune checkpoint ligand, programmed cell death 1 ligand 1 (PD-L1), is expressed in various tumors and associated with response to drugs that target programmed cell death protein 1. Previous studies have estimated the level of PD-L1 expression among different stages of thymoma and thymic carcinoma to evaluate its potential use as a diagnostic factor; however, its varying expression level has been problematic. We conducted this meta-analysis of published literature to evaluate PD-L1 expression in thymomas and thymic carcinomas.

METHODS

We analyzed 12 studies that included 320 patients with type A/AB/B1 thymoma, 225 patients with type B2/B3 thymoma, and 180 patients with thymic carcinoma.

RESULTS

No difference in PD-L1 expression level was found between the B2/B3 vs C groups (odds ratio [OR], 0.67; 95% confidence interval [CI], 0.26, 1.76; p = 0.42). However, the heterogeneity was very high (I² = 78%), and a significant difference was found between groups A/AB/B1 and B2/B3 (OR, 0.22; 95% CI, 0.12, 0.41; p < 0.001), with a relatively low heterogeneity (I² = 55%).

CONCLUSION

PD-L1 positivity might be a useful factor to differentiate type A/AB/B1 thymoma from type B2/B3 and thymic carcinoma. This result might be valuable for potential anti PD-L1 treatment in thymoma and thymic carcinoma.

PD-L1 Expression and Tumor-Infiltrating Lymphocytes in Thymic Epithelial Neoplasms

Thymic epithelial tumors (TETs) are rare malignant mediastinal tumors that are difficult to diagnose and treat. The programmed death 1 (PD-1) receptor and its ligand (PD-L1) are expressed in various malignant tumors and have emerged as potential immunotherapeutic targets. However, the immunobiology of TETs is poorly understood. We evaluated PD-L1 expression and the presence of tumor-infiltrating lymphocytes (CD8 and CD3 expression) in surgical TET specimens from 39 patients via immunohistochemistry and determined their relation to clinicopathological parameters. Cases with membranous reactivity of the PD-L1 antibody in ≥1% of tumor cells were considered positive. Positive PD-L1 expression was observed in 53.9% of cases. Histologically, PD-L1 expression was positive in 2/6 type A, 2/6 type AB, 3/9 type B1, 4/4 type B2, 5/6 type B3, and 5/8 type C TET cases. Thus, the number of cases with PD-L1 expression and the percent expression of PD-L1 were significantly higher in more aggressive thymomas (type B2 or B3). CD3+ and CD8+ tumor-infiltrating lymphocytes were diffusely and abundantly distributed in all cases. These data suggest that a PD-1/PD-L1 blockade is a promising treatment for TETs, with more beneficial treatment effects for aggressive thymomas such as type B2 or B3.

Immune checkpoints in thymic epithelial tumors: challenges and opportunities

Thymic malignancies are rare mediastinal cancers, classified according to the World Health Organization's histopathologic classification which distinguishes thymomas from thymic carcinomas. One key consideration when discussing immunotherapy for thymic epithelial tumors is that one-third of patients diagnosed with thymomas present at the time of diagnosis with autoimmune disorders, the most common being myasthenia gravis. The first step in the understanding of autoimmunity in thymic epithelial tumors is to distinguish true autoimmune disorders from paraneoplastic syndromes; besides pathophysiology, clinical correlates, impact on oncological management and survival may differ strongly. Autoimmune disorders are related to a deregulation in the physiological role of the thymus (i.e. to induce central tolerance to tissue self-antigens) through control of differentiation and subsequent positive and negative selection of immature T cells; from a clinical standpoint, in thymomas, once autoimmune disorders are present, they may not regress significantly after thymectomy. PD-L1 expression, while observed in more than 90% of epithelial cells of the normal thymus with a medullar tropism respecting Hassall's corpuscles, has also been identified in thymomas and thymic carcinomas using various immunohistochemistry protocols. Immune checkpoint inhibitors of the PD-1/PD-L1 axis have been assessed in advanced and metastatic thymic epithelial tumors, mainly thymic carcinomas. Several case reports have been published, and four trials have assessed the efficacy and safety of these inhibitors. Immunotherapy is not standard given the frequent occurrence of severe autoimmune disorders, and clinical trials are ongoing.

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Thymic malignancies are rare tumors.

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Advanced, metastatic and refractory thymic tumors may be treated with chemotherapy.

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Autoimmune disorders, such as myasthenia gravis, are observed in 30% of cases.

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PD-L1 expression is a hallmark of thymic epithelial cells.

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Immunotherapy is not standard, given the occurrence of autoimmune disorders.

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.

Nomogram to predict thymoma prognosis: A population-based study of 1312 cases

Background

A thymoma is a common cancer within the anterior mediastinum; however, the prognostic characteristics have not been established. The aim of this study was to identify the prognostic factors and develop a nomogram for the prognostic prediction of patients with thymoma based on data from the Surveillance, Epidemiology, and End Results (SEER) database.

Methods

Patients with thymomas diagnosed between 1983 and 2014 were selected. Overall survival (OS) was estimated using the Kaplan–Meier method with the log‐rank test. Univariate and multivariate Cox proportional hazards regression analyses were performed to identify the independent prognostic factors, from which a nomogram for thymomas was created. External validation of the nomogram was performed using data from our center.

Results

A total of 1312 patients with thymomas were enrolled. Age, tumor size, Masaoka–Koga stage, chemotherapy administered, and surgery type were independent prognostic factors for OS. A nomogram for OS was formulated based on the independent prognostic factors and validated using an internal bootstrap resampling approach, which showed that the nomogram exhibited a sufficient level of discrimination according to the C‐index in training (0.713, 95% confidence interval 0.685–0.741) and (0.746, 95% confidence interval 0.625–0.867) validation cohorts.

Conclusion

Several prognostic factors for thymomas were identified. The nomogram developed in this study accurately predicted the 5‐year and 10‐year OS rates of patients with thymomas based on individual characteristics. Risk stratification using the survival nomogram could optimize individual therapy and follow‐up.

Activation of the mTOR/ Akt pathway in thymic epithelial cells derived from thymomas

The pathogenesis of thymic epithelial tumors remains poorly elucidated. The PIK3/Akt/mTOR pathway plays a key role in various cancers; interestingly, several phase I/II studies have reported a positive effect of mTOR inhibitors in disease control in thymoma patients. A major limit for deciphering cellular and molecular events leading to the transformation of thymic epithelial cells or for testing drug candidates is the lack of reliable in vitro cell system. We analyzed protein expression and activation of key players of the Akt/ mTOR pathway namely Akt, mTOR, and P70S6K in eleven A, B and AB thymomas as well as in normal thymuses. While only Akt and phospho-Akt were expressed in normal thymuses, both Akt and mTOR were activated in thymomas. Phospho-P70S6K was expressed in all thymic tumors whatever their subtypes, and absent in normal thymus. Interestingly, we report the activation of Akt, mTOR and P70S6 proteins in primary thymic epithelial cells maintained for short period of time after their derivation from seven AB and B thymomas. Finally, we showed that rapamycin (100 nM) significantly reduced proliferation of thymoma- derived epithelial cells without inducing cell death. Our results suggest that the activation of the Akt/ mTOR pathway might participate to the cell proliferation associated with tumor growth. Ultimately, our data enhance the potential role of thymic epithelial cells derived from tissue specimens for in vitro exploration of molecular abnormalities in rare thymic tumors.

Best practices for the management of thymic epithelial tumors: A position paper by the Italian collaborative group for ThYmic MalignanciEs (TYME)

Thymic epithelial tumors (TETs) are a heterogenous group of rare tumors, with a complex histopatological classification. Furthermore, the recent introduction of the first TNM staging system, that is scheduled to replace the Masaoka-Koga system, may create further difficulties in TET management, that remains challenging. Several guidelines for treatment of TETs are available and provide recommendations based mainly on non randomized trials and retrospective or limited series. Often the lack of evidence leads to formulation of indications based on expert opinions. As for other rare cancers it is crucial to create networks to coordinate the work among centres involved in treatment of these diseases in order to offer the best diagnostic and therapeutic tools. For this purpose, in 2014 a network named TYME (ThYmic MalignanciEs), was founded in Italy with the aim of improving care and research in TETs. In September 2017 a panel of multidisciplinary experts from TYME network and from other Italian centres strongly involved in TET diagnosis and treatment convened a first Italian Expert meeting together with representatives of association for patients affected by rare thoracic cancers Tu.To.R, to explore how these tumors are managed in the different centres of Italy compared to ESMO guidelines. In this paper we summarize the issues discussed during that meeting and we propose recommandations based on Masaoka Koga and the new TNM staging system.

Cytoreductive Pleurectomy and Intrathoracic Chemohyperthermia for Pleural Relapse of Thymomas

Several surgical procedures, from debulking to extrapleural pneumonectomy, may be applied for stage IVa Masaoka thymomas, but their efficiency is still controversial. Case studies have favored R₀ resection as the cornerstone of multimodal therapy for locoregional metastatic extension. This report describes a standardized procedure combining a cytoreductive surgical procedure and intrathoracic chemohyperthermia on a 46-year-old patient presenting with B2 thymoma and synchronous unilateral pleural metastasis.

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.

Pembrolizumab for Patients With Refractory or Relapsed Thymic Epithelial Tumor: An Open-Label Phase II Trial

PURPOSE

Limited treatment options exist for patients with thymic epithelial tumor (TET) whose disease progresses after platinum-based chemotherapy. We conducted a phase II study of pembrolizumab in patients with TET to evaluate its efficacy and safety.

METHODS

Patients with histologically confirmed TET whose disease progressed after at least one line of platinum-based chemotherapy were eligible for the study. Patients were excluded if they had an active autoimmune disease requiring systemic treatment within the past year or documented history of clinically severe autoimmune disease. Patients received 200 mg of pembrolizumab intravenously every 3 weeks until tumor progression or unacceptable toxicity. The primary objective of response rate was assessed every 9 weeks by investigators.

RESULTS

Of 33 patients enrolled, 26 had thymic carcinoma and seven had thymoma. Of seven thymoma, two (28.6%; 95% CI, 8.2% to 64.1%) had partial response, and five (71.6%) had stable disease. Of 26 thymic carcinoma, five (19.2%; 95% CI, 8.5% to 37.9%) had partial response and 14 (53.8%) had stable disease. The median progression-free survival was 6.1 months for both groups. The most common adverse events of any grade included dyspnea (11; 33.3%), chest wall pain (10; 30.3%), anorexia (seven; 21.2%), and fatigue (seven; 21.2%). Five (71.4%) of seven patients with thymoma and four (15.4%) of 26 patients with thymic carcinoma reported grade ≥ 3 immune-related adverse events, including hepatitis (four; 12.1%), myocarditis (three; 9.1%), myasthenia gravis (two; 6.1%), thyroiditis (one; 3.0%), antineutrophil cytoplasmic antibody-associated rapidly progressive glomerulonephritis (one; 3.0%), colitis (one; 3.0%), and subacute myoclonus (one; 3.0%).

CONCLUSIONS

Pembrolizumab showed encouraging antitumor activity in patients with advanced TET. Given the high incidence of autoimmunity, additional studies are needed to identify those who can benefit from pembrolizumab without immune-related adverse events.

Thymic tumors and immune checkpoint inhibitors

Thymoma and thymic carcinoma, known as the most common features of thymic epithelial tumors (TETs), are thoracic malignancies displaying varied clinical features and prognosis. These neoplasms being frequently ineligible for surgical complete resection as a curative treatment because of extensive tumor spread, effectual nonsurgical treatments are needed; however, an optimal chemotherapeutic regimen has not been identified, although some regimens have been shown to be active. Immunotherapy is effective for other malignancies and may be promising as a therapeutic alternative for refractory TETs. Thus far, several studies have determined the expression of programmed death ligand 1 (PD-L1) and programmed death 1 (PD-1) in TETs, including its clinicopathological and prognostic significance. The results have been conflicting due to the different immunohistochemical antibodies employed and distinct cutoff values. However, many authors identified abundant PD-L1 expression in TETs, which is considered as an important predictive factor for therapeutic effect of PD-1 inhibitors in other malignant tumors. In some clinical trials, an acceptable clinical efficacy of PD-1 inhibitor for TETs has been reported as expected; however, concerns regarding immunological adverse events have been raised. To optimize these therapeutic agents for refractory TETs, additional studies which evaluate clinical availabilities of immunotherapeutic drugs and characterize their basic mechanisms of action against immunotherapeutic targets are both urgently required.

Neuroendocrine tumors of the thymus: the oncologist point of view

Thymic malignancies represent a heterogeneous group of rare thoracic cancers, which are classified according to the World Health Organization (WHO) histopathologic classification that distinguishes thymomas from thymic carcinomas and neuroendocrine tumors; neuroendocrine thymic tumors (NETTs) exhibit the same histological spectrum as in other anatomical locations, although with different frequencies. NETTs represent around 2% of all neuroendocrine tumors, and about 5% of all thymic malignancies. Overall, the management of patients with NETTs tumors requires continuous multidisciplinary expertise at any step of the disease progression. Systemic treatment relies on cytotoxic chemotherapy, as well as on somatostatin analogues and everolimus. Systemic treatment may be delivered in a curative-intent approach, for patients presenting with locally-advanced tumor at the time of diagnosis, with invasion of intra-thoracic neighboring structures. In such cases, chemotherapy has been used in an induction setting, to reduce the tumor burden-possibly allowing subsequent surgery and/or radiotherapy-or as a postoperative treatment if the tumor was resectable upfront, to reduce the risk of recurrence and achieve prolonged disease control. Systemic therapies are also a palliative-intent treatment of unresectable, metastatic, and recurrent NETTs. Chemotherapy may then be an option for aggressive disease, but somatostatin analogues and everolimus are suitable as well. Alternative options are emerging through clinical trials. As no dedicated study has ever been conducted, recommendations for systemic treatment in NETTs have been mostly based on retrospective cohorts of limited numbers patients, especially in the advanced disease setting, and expert opinion based on experience from primary pulmonary, as well as gastro-intestinal neuroendocrine tumors, for which clinical trials have been conducted.

Multidisciplinary management of thymic carcinoma

Thymic carcinomas represent approximately 10% of thymic tumors. In our approach to patients with thymic carcinoma, we emphasize multimodality treatment with close communication between the pathologist, thoracic surgeon, medical oncologist, and radiation oncologist. Given the paucity of high-quality clinical research data, treatment decisions are guided by a small amount of prospective trial data, retrospective reports, and clinical experience. Surgical management of thymic carcinoma must account for the more aggressive biology, higher degree of local invasion of neighboring structures, greater propensity for nodal metastasis, and higher risk of distant metastatic disease. Although surgical resection remains the most important component in the management of localized thymic tumors, radiation therapy (RT) may be used as adjuvant therapy after surgical resection or as the definitive treatment modality in patients who are deemed unresectable because of medical comorbidities or technical reasons. Systemic therapy for thymic carcinoma is used in two clinical scenarios: preoperative treatment and palliative therapy. First-line, platinum-based chemotherapy regimens are associated with response rates between 22% and 75%. Recent data from targeted therapy trials do not reveal a clear role for targeted therapies for patients with thymic carcinoma.

Correlation between S-1 treatment outcome and expression of biomarkers for refractory thymic carcinoma

BACKGROUND

Thymic carcinoma is a rare cancer with minimal evidence of a survival benefit following chemotherapy. An oral fluoropyrimidine of S-1, however, is the recommended active cytotoxic chemotherapy agent for refractory thymic carcinoma based on a case series, whereas sunitinib or everolimus are recommended as molecular-targeted agents based on Phase II trials. We retrospectively investigated the efficacy of S-1 for refractory thymic carcinoma and performed a biomarker analysis.

METHODS

We assessed the clinicopathological variables of 14 consecutive patients who underwent S-1 for refractory thymic carcinoma and correlated the clinical outcomes with potential biomarkers using paraffin-embedded cancer tissues of eight patients in the cohort.

RESULTS

A total of 178 thymic malignancies were identified, of whom 14 patients included 12 cases of squamous cell carcinoma, one lymphoepithelioma-like carcinoma, and one undifferentiated carcinoma. Six patients exhibited a partial response (42.9 %: 95 % confidence interval [CI], 21.4-67.4) and the disease control rate was 85.7 % (60.0-96.0 %). After a median follow-up of 24.2 months, the median progression-free survival was 8.1 months (range, 2.6-12.2 months), and median overall survival was 30.0 months (range, 6.2-41.9 months). No significant correlation between biomarker expression and response was noted. However, thymidine synthase (TS)/dihydropyrimidine dehydrogenase and TS/orotate phosphoribosyltransferase were observed.

CONCLUSIONS

S-1 for refractory thymic carcinoma offered clinical activity and achieved an 85 % disease control rate. Although the biomarkers did not correlate with clinical outcome, the study results showed efficacy of S-1 as a cytotoxic chemotherapy for refractory thymic carcinoma, which warrants future investigation.

Clinicopathologic and Prognostic Implications of Programmed Death Ligand 1 Expression in Thymoma

BACKGROUND

Programmed death ligand 1 (PD-L1) has been reported to be expressed in various malignancies and is considered to be a prognostic factor and an immunotherapeutic target. The aim of this study was to characterize PD-L1 expression in thymoma and determine statistical associations between this expression and clinical features.

METHODS

We reviewed formalin-fixed, paraffin-embedded tissue specimens from 82 thymoma cases accumulated at Kurume University, the majority of which achieved surgical complete resection. Expression of PD-L1 was evaluated by immunohistochemistry. Statistical associations between PD-L1 expression and clinicopathologic features were evaluated by using χ(2) test and Fisher's exact test. Disease-free survival and overall survival curves were established by the Kaplan-Meier method and compared using a log-rank test. Predictive factors for disease-free survival after complete resection were analyzed by using a Cox proportional hazards model in univariate and multivariate analysis.

RESULTS

Overall, 44 thymoma cases (54%) revealed high PD-L1 expression. High PD-L1 expression was statistically associated with Masaoka stage III/IV disease (p = 0.043) and World Health Organization type B2 or B3 thymoma (p = 0.044). Disease-free survival after complete resection in high PD-L1 expression was significantly worse than that in low PD-L1 expression (p = 0.021), although there was no significant difference in overall survival (p = 0.957). Multivariate analysis also revealed high PD-L1 expression as an independent risk factor for recurrence (p = 0.008).

CONCLUSIONS

Characterization of PD-L1 expression in thymoma should enable more effective clinical approaches, including prognostic stratification of patients and potential use of anti-PD-L1 antibody immunotherapy.

Gemcitabine in patients previously treated with platinum-containing chemotherapy for refractory thymic carcinoma: radiographic assessment using the RECIST criteria and the ITMIG recommendations

BACKGROUND

The key drugs for chemotherapy of thymic carcinoma are gradually being revealed in phase II and conventional retrospective studies. Gemcitabine is regarded as one of these key drugs according to the findings of clinical trials in which it was combined with capecitabine. However, the activity of single-agent gemcitabine concerning refractory thymic carcinoma remains unclear.

PATIENTS AND METHODS

We conducted a retrospective review of the medical records of refractory thymic carcinoma patients previously treated with platinum-containing chemotherapy between 1980 and 2014.

RESULTS

Of all 11 patients in this study, the objective response rate regarding gemcitabine was 36.4 % [95 % confidence interval (CI) 15.2-64.6] using the RECIST criteria and the response criteria proposed by the ITMIG. The median progression-free survival time was 4.3 months (95 % CI 0.7-11.0). The survival time from the start of gemcitabine treatment was 28.5 months (95 % CI 5.5-47.8), and from the start of first-line chemotherapy was 46.5 months (95 % CI 7.3-47.8).

CONCLUSIONS

Gemcitabine achieved a moderate response and has the potential to be used as a key drug for thymic carcinoma. Some patients treated with gemcitabine demonstrated prolonged cancer control even in later lines of chemotherapy.

Docetaxel for platinum-refractory advanced thymic carcinoma

OBJECTIVE

Thymic carcinoma is a rare mediastinal neoplasm. While platinum-based chemotherapy has been reported to be effective for advanced thymic carcinoma in a first-line setting, little information is available regarding the benefits of salvage chemotherapy for platinum-refractory thymic carcinoma. This study assessed the efficacy and safety profiles of docetaxel monotherapy for platinum-refractory thymic carcinoma.

METHODS

A total of 13 thymic carcinoma patients treated with docetaxel monotherapy in a second- or later-line setting between January 2003 and April 2014 were retrospectively reviewed. The median age was 61 years (range, 41-75 years).

RESULTS

The overall response rate and disease control rate were 31% [95% confidence interval (CI), 6-56%] and 77% (95% CI, 54-100%), respectively. The median progression-free survival and overall survival after docetaxel monotherapy were 5.5 months (95% CI, 2.3-6.5 months) and 24.0 months (95% CI, 9.4-31.2 months), respectively. The most common Grade ≥3 toxicity was neutropenia (62%). No incidents of febrile neutropenia and no treatment-related deaths were recorded.

CONCLUSIONS

This retrospective analysis demonstrated that docetaxel was active against platinum-refractory thymic carcinoma with acceptable toxicities. Docetaxel monotherapy might be a promising therapeutic option for patients with platinum-refractory thymic carcinoma.

Response to cytotoxic chemotherapy in patients previously treated with palliative-intent chemotherapy for advanced thymic carcinoma

BACKGROUND

Clinical efficacy of second- and later-line chemotherapy for patients with thymic carcinoma previously treated with chemotherapy remains uncertain; limited data are available about this carcinoma because of its rarity. The aim of this study was to investigate effective chemotherapy for patients with thymic carcinoma previously treated with chemotherapy using a retrospective analysis of responses and times to event.

PATIENTS AND METHODS

We conducted a retrospective review of the medical records of 23 advanced thymic carcinoma patients previously treated with palliative-intent chemotherapy between 1980 and 2014 in our institution. Clinical demographic characteristics, agents, response, and time to treatment failure for each treatment line and overall survival were reviewed. Factors expected to be associated with survival rates were analyzed. Differences in survival were assessed using Kaplan-Meier analysis and univariate and multivariate Cox proportional hazards regression analyses.

RESULTS

The study included 13 men (56.5%) and 10 women (43.5%). The median age at diagnosis was 58.5 years. The most common histological subtypes were squamous cell carcinoma (16 patients [69.6%]), followed by neuroendocrine carcinoma (4 patients [17.4%]). The objective response rates of first-, second-, third-, and fourth-line chemotherapy were 60.9%, 39.1%, 23.1%, and 25.0%, respectively. The median survival time was 18.8 months (95% confidence interval, 7.5-40.9 months). Uni- and multivariate analyses of all assessed variables failed to identify any statistically significant indicators of overall survival.

CONCLUSION

Patients with thymic carcinoma previously treated with palliative-intent chemotherapy might respond to second- or later-lines of cytotoxic chemotherapy.

Key components of chemotherapy for thymic malignancies: a systematic review and pooled analysis for anthracycline-, carboplatin- or cisplatin-based chemotherapy

Purpose

Thymic malignancies, comprising thymoma and thymic carcinoma, are rare. Consequently, optimal chemotherapy for advanced thymic malignancies remains controversial. Platinum-based chemotherapy is currently the consensus treatment based on the results of single-arm phase II trials and retrospective investigations. However, comparison of cisplatin-based and carboplatin-based chemotherapy has yet to be undertaken; the effectiveness of the addition of anthracycline also remains uncertain.

Methods

In the present study, clinical trials and retrospective data regarding platinum-based chemotherapy were analyzed. The endpoint was the response rate to each chemotherapy. For advanced thymoma, we compared platinum with anthracycline-based chemotherapy and platinum with non-anthracycline-based chemotherapy. For advanced thymic carcinoma, anthracycline-based versus non-anthracycline-based chemotherapy and carboplatin-based versus cisplatin-based chemotherapy were compared. This analysis included a retrospective study of response of advanced thymic carcinoma to irinotecan and cisplatin in our institution.

Results

The response rate for the 314 patients from 15 studies with advanced thymoma, including both prospective and retrospective data, was 69.4 % [95 % confidence interval (CI) 63.1–75.0 %] for platinum with anthracycline-based chemotherapy and 37.8 % (95 % CI 28.1–48.6 %; p < 0.0001) for platinum with non-anthracycline-based chemotherapy. The response rates after anthracycline-based and non-anthracycline-based chemotherapy for advanced thymic carcinoma were similar (41.8 vs. 40.9 %; p < 0.91), whereas the response rates after cisplatin-based and carboplatin-based chemotherapy for advanced thymic carcinoma differed significantly (53.6 vs. 32.8 %; p = 0.0029) in 206 patients from 10 studies.

Conclusions

Platinum with anthracycline-based chemotherapy is an optimal combination for advanced thymoma. For advanced thymic carcinoma, cisplatin-based chemotherapy may be superior to carboplatin-based chemotherapy.

Management of thymic tumors: a European perspective

Thymic tumors are rare mediastinal tumors, which are considered as orphan diseases due to their low prevalence. The most recent histologic classification divides thymic tumors into thymomas, thymic carcinomas (TC) and neuroendocrine thymic tumors (NETT). Until recently, clinical research on thymic tumors has been primarily represented by single-institution experiences usually scattered over a long time period in order to accumulate a sufficient number of patients for clinical analysis. Europe has played a pivotal role in the advancement of the clinical research on thymus in the past years. In the last decade, there has been an increased interest in thymic malignancies in the scientific community. The European Society of Thoracic Surgeons (ESTS), the most representative society of general thoracic surgeons in the world, established a dedicated thymic working group in 2010 with the intent to provide a platform among ESTS members with a specific interest in thymic malignancies. The present review is intended to provide, through the description of the activity of the ESTS thymic working group and its published results, an overview of the European contribution to the thymic research. A brief overview of the state-of-the-art of clinical presentation, diagnosis, staging and histologic classification of thymic tumors is also provided, along with the most recent therapeutic advancements.

Invasive thymoma disseminated into the pleural cavity: mid-term results of surgical resection

OBJECTIVES

The optimal strategy for pleural dissemination of advanced thymoma remains controversial, while a potential benefit from macroscopic clearance of disseminations has been reported. In this study, we review our mid-term results of surgical resection of pleural disseminations of invasive thymoma.

METHODS

Data from patients with pleural dissemination synchronously or metachronously to primary invasive thymoma who underwent surgical resection from 1991 to 2012 at our institute were retrospectively reviewed.

RESULTS

Of 136 thymoma patients who underwent surgery during the study period, 13 consecutive patients with pleural dissemination (synchronous: 7, metachronous: 6) with a median age of 49 years (range: 27-78 years) at the time of dissemination resection were identified. No patients presented with haematogenous metastases. Operative procedures included the thorough resection of visible disseminated nodules in 11 patients and extrapleural pneumonectomy (EPP) in 2 patients. The median number of resected nodules was 6 (range: 1-52). The median follow-up was 948 days (range: 38-4025 days). One patient died of postoperative bleeding, but there were no tumour-related deaths during the study period. Pleural recurrence was found in 9 cases, including 2 EPP cases, and among them, 3 underwent repeated resection. The overall survival and the recurrence-free survival ratio at 5 years was 92.3 and 33.3%, respectively. Five patients, including 2 repeated resection cases, remained tumour-free at the final observation.

CONCLUSIONS

Resection of pleural dissemination of invasive thymoma can be performed in selected patients and may offer optimal local control as part of a multimodal strategy.