Long lasting efficacy of sorafenib in a heavily pretreated patient with thymic carcinoma

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.

Emerging therapies in thymic epithelial tumors (Review)

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

Apatinib in patients with recurrent or metastatic thymic epithelial tumor: a single-arm, multicenter, open-label, phase II trial

BACKGROUND

Thymic epithelial tumors (TETs) are rare malignancies and the treatment options are limited. We aimed to evaluate the efficacy and safety of apatinib, an angiogenesis inhibitor, in advanced TETs.

METHODS

This was an open-label, single-arm, phase II trial at three centers in China. Patients with TET who had progressed after failure of at least one line of platinum-based chemotherapy were enrolled. Patients received apatinib 500 mg orally per day. The primary endpoint was objective response rate (ORR). Secondary endpoints were progression-free survival (PFS), overall survival (OS), disease control rate (DCR), and safety.

RESULTS

From June 29, 2017, to April 18, 2019, 25 patients were enrolled. At data cut off (September 30, 2021), one patient achieved complete response, nine achieved partial response, and 11 achieved stable disease, with an ORR of 40% (95% CI 21-61%) and DCR of 84% (95% CI 64-95%). The median PFS was 9.0 (95% CI 5.4-12.6) months. The median OS was 24.0 (95% CI 8.2-39.8) months. All patients reported treatment-related adverse events (TRAEs). Grade 3 TRAEs occurred 26 times in 15 patients. No grade 4 or 5 toxicities occurred.

CONCLUSIONS

This is the first trial of apatinib for the treatment of TETs. Apatinib showed promising antitumor activity and the toxicities were tolerable and manageable.

The role of targeted therapy in thymic carcinoma

Thymic carcinoma is a rare entity and can be distinguished from benign thymomas by their aggressive nature and poor prognosis. The National Comprehensive Cancer Network guidelines recommend resection followed by adjuvant platinum-based chemotherapy for resectable tumors. However, the outcomes for metastatic or relapsed thymic carcinomas are poor with no regimen showing a consistent benefit. Moreover, the relative rarity of these tumors makes clinical trials difficult. Molecular analysis of thymomas shows a high incidence of genetic mutations and targeted therapy holds promise. We will briefly outline and review the current role of targeted therapy in thymic cancer.

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

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

Targeted therapy for thymic epithelial tumors: a new horizon? Review of the literature and two cases reports

Surgical resection remains the cornerstone of therapy for early-stage thymic epithelial tumors (TETs), while in advanced or recurrent forms, a multimodality approach incorporating radiation and chemotherapy is required. Given the absence of effective treatment options for metastatic/refractory TETs and the poor related prognosis, there is a compelling need to identify promising 'drugable' molecular targets. Initial reports of activity from targeted agents in TETs derived from anecdotal cases have been often associated with specific activating mutations. Only in recent years, several agents have been formally investigated into prospective clinical trials, with varying success rates. We reviewed the literature on targeted therapy in TETs along with two cases of thymoma achieving striking responses to sorafenib in combination with lapatinib.

c-kit mutation-positive advanced thymic carcinoma successfully treated as a mediastinal gastrointestinal stromal tumor: A case report

Thymic carcinoma is an exceptionally rare tumor, which has a very poor prognosis, differing from thymoma. Although cytotoxic chemotherapy is commonly used to treat advanced thymic carcinoma, its effectiveness has not been found to be sufficient. There are several reports that thymic carcinoma also harbors an oncogenic driver mutation, similar to lung cancer. A patient with a c-kit mutation-positive thymic carcinoma received imatinib followed by sunitinib consecutively, which are both c-Kit inhibitors. Although the patient had achieved long-term disease control for 21 months, the primary lesion and pulmonary metastases had increased in size by November, 2014. Following failure of imatinib treatment, the patient received sunitinib, a multiple kinase inhibitor, initiated in December, 2014. Following administration of sunitinib, a computed tomography scan revealed a partial response and the disease was effectively controlled with continued sunitinib treatment for 6 months, up to June, 2015. The patient achieved long-term disease control (~27 months) with imatinib followed by sunitinib. The efficacy of consecutive molecular-targeted therapy for thymic carcinoma was demonstrated in this case. Therefore, thymic carcinoma with oncogenic driver mutations should be treated with molecular-targeted agents rather than with cytotoxic drugs, and it may be suitable to treat c-kit mutation-positive thymic carcinoma as a mediastinal gastrointestinal stromal tumor.

Do thymic malignancies respond to target therapies?

A best evidence topic in cardiothoracic surgery was written according to a structured protocol. The question addressed was 'Do thymic malignancies respond to target therapies?' Altogether, 347 papers were found using the reported search, of which, in our opinion, 16 papers represented the best evidence to answer the clinical question. The authors, journal, date and country of publication, patient group studied, study type, relevant outcomes and results of these papers were tabulated. We did not find any randomized controlled trials on target therapies for the thymic malignancies, due to the very small incidence of this tumour, and it seems unlikely that there will be any such trials in the foreseeable future. Three studies on target therapies showed that several cases of thymic malignancies were reported to have partial response (PR) to epidermal growth factor receptor tyrosine kinase inhibitors such as cetuximab and erlotinib, whereas, one study on erlotinib and another on gefitinib showed no activity. Proto-oncogene c-KIT (KIT) mutant thymic carcinomas were noted to benefit from target therapies, implying that systematic sequencing of KIT in thymic carcinoma tumours may be warranted for optimal patient selection. A study that investigated the efficacy of cixutumumab, a fully human IgG1 monoclonal antibody that binds to insulin-like growth factor 1 receptor, indicated that relapsed thymomas tended to respond, whereas thymic carcinoma did not. The antiangiogenesis agent belinostat had modest antitumour activity in heavily pretreated thymoma, but no response to thymic carcinoma was found. Several cases with metastatic thymic carcinoma showed that multitargeted kinase inhibitors, such as sunitinib and sorafenib, were effective. We concluded that, as the side-effects of the agents were tolerable in almost all reported cases, target therapies can be an option for patients with heavily pretreated thymoma.

Available evidence and new biological perspectives on medical treatment of advanced thymic epithelial tumors

Thymic epithelial tumors (TETs) are rare primary mediastinal tumors arising from thymic epithelium. Their rarity and complexity hinder investigations of their causes and therapy development. Here, we summarize the existing knowledge regarding medical treatment of these tumors, and thoroughly review the known genetic aberrations associated with TETs and the present status of potential biological treatments. Epidermal growth factor receptor (EGFR), stem-cell factor receptor, insulin-like growth factor-1 receptor (IGF1R), and vascular endothelial growth factors (VEGF-A, VEGF-B, and VEGF-2) are overexpressed in TETs. EGFR overexpression in TETs is associated with higher stage, and IGF1R overexpression has poor prognostic value. Data indicate that anti-IGF1R monoclonal antibodies, and inhibitors of angiogenesis, somatostatin receptors, histone deacetylase, mammalian target of rapamycin, and cyclin-dependent kinases may be active against TETs. Continued investigations in this field could lead to advancement of targeted and biological therapies for TETs.

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

Thymic malignancies represent a wide range of clinical, histological and molecular entities, with probably considerable heterogeneity even among tumors of the same histotype. Systemic chemotherapy with cisplatin-based regimens continues to represent the standard of care in metastatic or inoperable refractory/recurrent diseases and ADOC regimen (including cisplatin, doxorubicin, vincristine and cyclophosphamide) demonstrated the longer overall response rate and median survival in the first line setting, although no randomized trial is available; and there is still a lack of standard treatment after first-line failure. To date research efforts are focused on translational studies on molecular pathways involved in thymic tumors carcinogenesis, aimed to better understand and predict the efficacy of chemotherapy and targeted therapy. Recent molecular characterization includes identification of a number of oncogenes, tumor suppressor genes, chromosomal aberrations, angiogenic factors, and tumor invasion factors involved in cellular survival and proliferation and in tumor growth. The use of biologic drugs is currently not recommended in a routine practice because there are limited data on their therapeutic role in thymic epitelial tumors. Because of the lack of data from adequate-sized, prospective trials are required for validation and the enrolment of patients with advanced disease into available clinical trials has to be encouraged.

Phase I study of the safety, pharmacokinetics and antitumor activity of famitinib

PURPOSE

To evaluate the safety, tolerability, pharmacokinetics and antitumor activities of famitinib (famitinib L-malate), a novel oral multitargeting tyrosine kinase inhibitor that acts against vascular endothelial growth factor receptor-2, platelet-derived growth factor receptor, stem cell factor receptor (c-kit), FMS-like tyrosine kinase-3 receptor and protooncogene tyrosine kinase receptor in patients with advanced solid cancer.

METHODS

Patients received once daily oral famitinib. Doses were increased from 4 to 8, 13, 20, 27, 24, 25 and eventually 30 mg. Each cycle was defined as 28 days. The pharmacokinetic profile and various biomarkers were evaluated during the first cycle. Antitumor efficacy was evaluated every 8 weeks.

RESULTS

Fifty-four patients were evaluable for safety and efficacy. Dose-limiting toxicities were observed in 2 of 3 patients at 30 mg. The dose-limiting toxicities observed in the first cycle of famitinib treatment included hypertension, hand-foot skin reaction and diarrhea. Grade 3 hypertriglyceridemia/hypercholesterolemia and proteinuria were notable side effects in the subsequent treatment cycles. Other common side effects included bone marrow suppression, oral mucositis, fatigue, pain, elevated transaminase or bilirubin, peripheral sensory disturbance and hypothyroidism, most of which were mild to moderate in severity. Pharmacokinetic studies revealed no significant accumulation of famitinib or its major metabolite, M3. The half-lives of famitinib and M3 were approximately 28.7-33.8 and 41.3-47.7 h, respectively. Food demonstrated a minimal effect on the pharmacokinetics of famitinib. Eight partial responses were determined, including 6 cases of renal cell carcinoma, 1 case of gastrointestinal stromal tumor (GIST) and 1 case of alveolar soft part sarcoma. Fourteen patients demonstrated stable disease with various degrees of tumor shrinkage.

CONCLUSIONS

Famitinib is generally well tolerated. Famitinib demonstrates a wide spectrum of antitumor activities, which warrants further study in renal cell carcinoma, GIST, hepatocellular carcinoma and soft tissue sarcoma. The recommended dose for future phase II clinical trials is 25 mg.