Treatment outcomes and prognosis of immune checkpoint inhibitors therapy in patients with advanced thymic carcinoma: A multicentre retrospective study

The influence of PD-L1 expression levels on the efficacy of combination therapy in thymic epithelial tumors

BACKGROUND

The significant expression of PD-L1 in thymic epithelial tumors (TETs) has been confirmed, and immunotherapy and its combination therapy have been effective in TETs. However, there is no present evidence that the expression levels of PD-L1 affects the efficacy of combination therapy. Our study aimed to shed light on this relationship.

METHODS

Patients with thymic epithelial tumors (TETs) from multicenter hospitals were retrospectively identified. Objective response rate (ORR), progression-free survival (PFS), overall survival (OS), and immune-related adverse events (irAEs) in 22 patients were included. We divided the patients the 22 patients with PD-L1 test into three levels (high expression, low expression and no expression) and analyzed the relationship between the levels of PD-L1 expression and the efficacy of combination therapy.

RESULTS

Combination therapy showed an effective benefit in 22 patients with TETs, the median PFS (mPFS) was 16 months (95% CI: 8.5-23.5) and the median OS (mOS) was 38 months (95% CI: 21.5-54.5). Cox-regressive analysis found whether PD-L1 expression affected the PFS of patients (p = 0.017). Among the patients with PD-L1 expression, the levels of expression were correlated with curative effect (Kruskal-Wallis test, PFS: P = 0.012; OS: P = 0.01), and high expression group was along with better efficacy than low expression (Wilcoxon test, P = 0.01). Moreover, in 17 patients treated with immunotherapy combined with chemotherapy, the expression of PD-L1 was also associated with efficacy (Kruskal-Wallis test, p = 0.021).

CONCLUSIONS

PD-L1 expression affects the PFS of patients. High expression of PD-L1 patients with TETs responded better to combination therapy, which could provide a therapeutic option in clinic. Besides, other targeted treatments should be considered.

Rechallenge immunotherapy after immune resistance in patients with advanced thymic carcinoma

BACKGROUNDS

Immunotherapy is effective for patients with advanced thymic carcinoma (TC). However, the effectiveness of rechallenge immunotherapy in patients who are resistant to immunotherapy has not been investigated.

METHODS

Thirty-five patients with advanced TC using immunotherapy between 2016 and 2023 at Zhejiang Cancer Hospital, The Second Affiliated Hospital of Nanchang University, and Fujian Cancer Hospital were evaluated in this study. Tumor response was evaluated according to the Response Evaluation Criteria in Solid Tumors version 1.1. Progression-free survival (PFS) and overall survival (OS) were calculated using the Kaplan-Meier method.

RESULTS

A total of 35 patients were included in this study. The median PFS (mPFS) for all patients was 5.43 months and the median OS (mOS) was 16 months. After rechallenge immunotherapy, only three patients achieved partial response, resulting in an overall response rate of 16.7%, and nine patients attained stable disease, resulting in a disease control rate of 66.7%. Patients who underwent rechallenge immunotherapy had shorter mPFS compared to chemotherapy (3.53 months vs. 6.00 months, P = 0.041). In addition, the incidence of Grade 3-4 treatment-related adverse events in these patients was 22.2%.

CONCLUSION

Rechallenge immunotherapy has poor efficacy in immunotolerant TC patients.

First Report of Pembrolizumab Activity in KIT-Mutated Thymic Carcinoma

The antitumor activity of immunotherapy is strongly influenced by the presence of driver gene mutations/translocations. For this reason, knowledge of the predictive value of specific genetic alterations in relation to anti-PD(L)1 activity is highly useful for the clinical decision making process in many solid tumors, particularly in Non-Small Cell Lung Cancer. Although data on the correlation between genetic alterations and response to immunotherapy are available in the majority of common cancers, data are lacking in the subset of patients with KIT-mutated Thymic Carcinoma (TC). As a consequence, although immunotherapy is a standard treatment for TC patients, the lack of this knowledge leads to uncertainty when proposing immunocheckpoint inhibitors in this subset of patients. Here we describe the first report of a patient with KIT-mutated TC who received the anti-PD1 agent pembrolizumab, which caused a sustained partial response. This case report of a sustained partial response achieved with pembrolizumab in a patient with KIT-mutated TC after progression to chemotherapy and imatinib may be supportive during clinical decision making for this extremely rare disease.

The Rare Entity of Basaloid Thymic Carcinoma: A Multicentric Retrospective Analysis from the Italian Collaborative Group for ThYmic MalignanciEs (TYME)

BACKGROUND

thymic basaloid carcinoma (BTC) is an extremely rare tumor, and very little data are available on BTC's biology, clinical behavior, drug sensitivity, and patient outcomes.

METHODS

We performed a retrospective observational study on patients diagnosed with BTC in 11 referral centers of TYME. All BTC diagnoses were reviewed by the referring pathologist.

RESULTS

Twenty-eight patients were identified. A total of 22/28 patients were included. Eighteen patients had TNM stage I-III disease, and all underwent surgery; three patients received preoperative chemotherapy, and 10 patients received adjuvant radiotherapy. With a median follow-up of 46 (1-133) months, median overall survival (mOS) and median relapse-free survival were not reached. At 48 months, OS was 77% (95%CI 43-92), and DFS was 63% (95%CI 30-83). The median OS of the 4 patients diagnosed with metastatic disease was 7 months. Six patients received first-line systemic treatment for metastatic disease, and all showed tumor responses. Anti-tumor activity was also observed with an anti-VEGFR TKI and a multi-TKI inhibitor combined with an anti-PD1 antibody. Next-generation sequencing performed in three tumor samples did not identify actionable alterations or microsatellite instability.

CONCLUSIONS

BTC is an extremely rare tumor that usually presents as a localized disease. Patients diagnosed with stage I-III disease can achieve long-term DFS, and efforts should be made to perform radical surgical resection combined with perioperative treatment whenever appropriate. Patients with advanced disease progression have a poor prognosis despite a high response rate to systemic treatments.

Comparison of Efficacy and Safety of Different Second-line Therapies for Patients With Advanced Thymic Carcinoma

AIMS

Thymic carcinoma (TC) is a rare form of highly invasive tumors. Currently, the standard first-line therapy involves paclitaxel plus carboplatin treatment, while the recommended regimen for second-line therapy remains uncertain. The purpose of this study is to explore the second-line mode of TC patients.

MATERIALS AND METHODS

We evaluated the outcome of subjects with advanced TC between 2009 and 2023 in three medical centers, retrospectively. Tumor response was evaluated according to the Response Evaluation Criteria in Solid Tumors, version 1.1 (RECIST v1.1). Kaplan-Meier was used for calculating Progression-free survival (PFS) and overall survival (OS). The factors affecting survival in the real world were evaluated by Cox analysis.

RESULTS

Totally 136 patients were included in this study, the median PFS (mPFS) for all subjects was 5.97 months, and the median OS (mOS) was 25.03 months. According to patient's treatment modes, they are divided into monotherapy (n = 95) and combination therapy (n = 41), PFS manifested the difference between two groups (5.17 vs. 9.00 months, P = 0.043). OS also indicated a significant distinction (22.50 vs. 38.00 months, P = 0.017). Furthermore, there was a significant difference in PFS between patients using immunotherapy combined with chemotherapy and those with antivascular therapy (8.57 vs. 13.10 months, P = 0.047).

CONCLUSION

In the second-line therapy for advanced TC, the efficacy of combination therapy was better than monotherapy, especially for immunotherapy combined with antivascular therapy.

Thymic epithelial tumor medical treatment: A narrative review

Thymic epithelial tumors, a malignancy originating in the thymus, are the commonest primary neoplasm of the anterior mediastinum; however, among thoracic tumors, they have a relatively low incidence rare. Thymic epithelial tumors can be broadly classified into thymic carcinoma and thymoma. As the cornerstone of thymic tumor treatment, surgery is the preferred treatment for early-stage patients, whereas, for advanced unresectable thymic tumors, the treatment is chemoradiotherapy. Targeted therapy is less effective for thymic tumors. Moreover, the use of immune checkpoint inhibitors as another effective treatment option for advanced unresectable thymic tumors, particularly thymomas, is limited owing to immune-related adverse effects. Here, we have summarized all pertinent information regarding chemotherapy, especially preoperative neoadjuvant chemotherapy, and chemotherapy in combination with other treatments, and reviewed the effectiveness of these procedures and recent advances in targeted therapy. In addition, we analyzed the efficacy and safety of immune checkpoint inhibitors in thymic epithelial tumors, to provide a holistic treatment view.

Chemotherapy versus chemotherapy plus immune checkpoint inhibitors for the first-line treatment of unresectable thymic carcinoma: A multicenter retrospective study

Thymic carcinoma (TC) is a rare malignant tumor with a poor prognosis, and there is currently limited data on the use of immunotherapy in patients with unresectable TC. In this study, data of patients with unresectable TC diagnosed from January 2017 were retrospectively collected from multiple centers. Treatment response, progression-free survival (PFS), overall survival (OS), survival-independent prognostic factor, and adverse events (AEs) were further analyzed. As a result, a total of 93 patients with unresectable TC were enrolled, of which 54 received first-line chemotherapy, and 39 received chemotherapy plus immune checkpoint inhibitors (ICIs). The objective response rate was 50% (27/54) in the chemotherapy group and 76.9% (30/39) in the chemotherapy plus ICIs group. The chemotherapy plus ICIs group achieved significant median PFS benefit (8.8 vs. 34.9 months, p < .001) and median OS benefit (41.8 months vs. not reached, p = .025). Multivariate analysis showed that ICIs and local therapy were independent prognostic factors for PFS. In addition, 17 patients developed immune-related AEs (IRAEs), of which 15 (38.5%) had Grade 1 or 2 IRAEs and 2 (5.1%) had Grade 3 IRAEs in the chemotherapy plus ICIs group. In conclusion, the efficacy of chemotherapy plus ICIs is superior to chemotherapy, and the adverse effects are manageable in patients with unresectable TC.

Poor efficacy of immune checkpoint inhibitor treatment in advanced thymic carcinoma patients with liver metastases

Background

Although immune checkpoint inhibitor treatment for advanced thymic carcinoma exhibits promising efficacy, factors that affect the efficacy and prognosis, including metastases sites, remain uncertain.

Objectives

Our study aimed to investigate the determinants of survival among patients with advanced thymic carcinoma who underwent immunotherapy in real-world settings, with implications for clinical practice.

Designs

Different therapy regimens of immunotherapy were produced to analyze the influence of liver metastases on survival and prognosis for advanced thymic carcinoma patients.

Methods

Data for advanced thymic carcinoma patients receiving immunotherapy and their metastases sites were collected for analysis from seven different hospitals between January 2015 and January 2023. Progression-free survival (PFS) and overall survival (OS) analyses were performed using the Kaplan-Meier method. Cox analysis was used to evaluate factors influencing survival.

Results

The present study analyzed 136 advanced thymic carcinoma patients from seven different hospitals.The PFS for all patients receiving immunotherapy was 6.4 months, while the OS was 24.0 months. The objective response rate was different for patients with liver and non-liver metastases (11.9% versus 37.2%, p = 0.003). The disease control rate values were also different between the two groups (47.6% versus 80.9%, p = 0.037). The PFS for patients with liver metastases demonstrated poor immunotherapy efficacy compared to patients with non-liver metastases (3.0 versus 8.0 months, p < 0.0001). The OS was also significantly different between these two patient groups (16.1 versus 29.1 months, p = 0.009).

Conclusion

Immunotherapy had poor efficacy in advanced thymic carcinoma patients with liver metastases.

Myasthenia Gravis Associated With Pembrolizumab for Relapsed Lung Cancer After Thymoma Resection

Immunotherapy has demonstrated clinical efficacy in patients with thymic epithelial tumors; however, there is the potential risk of serious immune-related adverse events (irAEs). Here, we report a case of myasthenia gravis (MG) associated with pembrolizumab treatment that developed after thymoma resection in a patient with lung adenocarcinoma. Symptoms of MG occurred 16 days after pembrolizumab administration and progressed rapidly, necessitating mechanical ventilation and tracheostomy. Even after tumor resection, careful monitoring is crucial for patients with thymic tumors being managed with immune checkpoint therapy, particularly regarding the development of severe irAEs.

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.

Chinese expert consensus on the diagnosis and treatment of thymic epithelial tumors

Thymic epithelial tumors (TETs) are a relatively rare type of thoracic tumor, accounting for less than 1% of all tumors. The incidence of TETs is about 3.93/10000 in China, slightly higher than that of European and American countries. For resectable TETs, complete surgical resection is recommended. Radiotherapy or chemotherapy may be used as postoperative adjuvant treatment. Treatment for advanced, unresectable TETs consist mainly of radiotherapy and chemotherapy, but there is a lack of standard first- and second-line treatment regimens. Recently, targeted therapies and immune checkpoint inhibitors have shown promising outcomes in TETs. Based on the currently available clinical evidences and the opinions of the national experts, the Thymic Oncology Group of Yangtze River Delta Lung Cancer Cooperation Group (East China LUng caNcer Group, ECLUNG; Youth Committee) established this Chinese expert consensus on the clinical diagnosis and treatment of TETs, covering the epidemiology, diagnosis, treatment, prognosis and follow-up of TETs.