Thoracic Sarcoma Research Articles

Extrapleural pneumonectomy for sarcoma: Outcomes of adult patients at a specialized center.

Extrapleural pneumonectomy (EPP) is a complex surgical procedure involving en-bloc resection of the parietal and visceral pleura, lung, pericardium, and ipsilateral diaphragm. Small case series of pleural-based sarcoma of predominantly pediatric patients suggest EPP may be a life-prolonging surgical option. We aimed to describe the characteristics and outcomes of adults who underwent EPP at a specialized sarcoma center. Clinicopathologic variables, surgical details, and follow-up information were extracted for patients undergoing EPP for pleural-based sarcoma between August 2017 and December 2020. Primary outcomes were event-free survival (EFS) and overall survival (OS) from the date of EPP. Secondary outcomes were disease-free interval (DFI) prior to EPP, and early and late postoperative complications. Eight patients were identified, seven with soft tissue sarcoma and one with bone sarcoma. Patients had either localized disease with a primary thoracic sarcoma, sarcoma recurrent to the thorax, or de novo metastatic disease. All patients underwent resection of their pleural-based sarcoma by an experienced cardiothoracic surgeon, and some patients had pre or postoperative treatment. The perioperative morbidity was comparable with previously published reports of EPP performed in mesothelioma patients. At median follow-up of 22.5 months, median EFS was 6.0 months and OS was 20.7 months. Six patients (75%) had disease recurrence; five (62.5%) died of progressive disease. Two patients (25%) had not recurred: one died of a radiation-related esophageal rupture, and one was alive with no evidence of disease at 37.0 months. Characteristics of those with the longest EFS included low-grade histology and achieving a metabolic response to preoperative chemotherapy. In adults with pleural-based sarcoma, EPP is rarely curative but appears to be a feasible salvage procedure when performed at specialized centers. Patient selection is critical with strong consideration given to multimodal therapy to optimize patient outcomes. In the absence of a confirmed response to neoadjuvant treatment, long term survival is poor and EPP should not be recommended.

Cytopathological characteristics of SMARCA4-deficient thoracic undifferentiated tumors in serous effusion

Objective: To investigate the clinicopathological characteristics of SMARCA4-deficient thoracic undifferentiated tumors, and the diagnostic value of the cells in serous effusion. Methods: Eleven cases of SMARCA4-deficient tumor were collected from the Affiliated Hospital of Hebei University, China from January 2018 to July 2023, which were diagnosed using cell block of serous effusion. The clinical, histopathological, immunohistochemical and molecular genetic features were reviewed, along with related literature. Results: All the 11 patients were males with ages ranging from 54 to 77 years (median 64 years). Nine patients were smokers and two had an unknown smoking history. Most of them complained of cough and dyspnea with pleural effusion. The primary tumor sites included lung (9 cases), thoracic wall (1 case), and mediastinum (1 case), while 3 patients had a history of lung surgery. Histologically, tumor cells were large and pleomorphic, with increased nuclear-cytoplasmic ratio. They also showed round nuclei, conspicuous nucleoli, and basophilic cytoplasm in serous effusion. Immunohistochemically, tumor cells in all cases were negative for SMARCA4/BRG1, CKpan and CK7, but positive for SMARCB1/INI1. Some of the cases were positive for CD34 (7/11), synaptophysin (4/11) and SALL4 (2/11). Histologically, monotonous tumor cells formed solid sheets or anastomosing islands with poor cell adhesion and rhabdoid morphology. Brisk mitotic figures were accompanied by large areas of necrosis. Some cases focally exhibited syncytia, and some had bright cytoplasm and vesicular chromatin. The immunohistochemical profiles in the tumor tissues were consistent with those of cytology. Six cases were negative for PD-L1 (22c3). Among the 6 cases analyzed by targeted next generation sequencing, concurrent SMARCA4 and TP53 mutations were detected in all 6 cases. Some of the 6 tumors showed mutations of STK11, CDKN2A, and MET, and amplification of ERBB2, exon deletion of BRCA2, etc. Follow-up information was available in all cases and ranged from 2 to 24 months. The patients showed metastases to various sites, including lymph node, liver, kidney, adrenal gland, brain, bone and other sites. Four patients died of the tumor. The survival time of 4 patients who underwent radical resection or radiofrequency ablation was more than 13 months. Conclusions: SMARCA4-deficient thoracic sarcoma is a rare but highly aggressive tumor with dismal prognosis and rhabdomyoid features. It is difficult to diagnose this disease using only serous effusion samples. This tumor thus warrants careful consideration. Accurate diagnosis can greatly improve early diagnosis and treatment of these tumors.

Thoracic SMARCA4-deficient undifferentiated tumor: current knowledge and future perspectives.

Thoracic SMARCA4-deficient undifferentiated tumor is a newly recognized disease entity characterized as a high-grade malignant neoplasm with an undifferentiated or rhabdoid phenotype. The tumor was initially identified as a subtype of thoracic sarcoma with SMARCA4 loss, but further investigation resulted in its classification as a subtype of epithelial malignancies in the current World Health Organization classification. SMARCA4-deficient undifferentiated tumor is highly aggressive and has a poor prognosis. Because of its rarity, an optimal treatment strategy has not yet been identified. In this review, we summarize the literature on SMARCA4-deficient undifferentiated tumor in terms of its clinical characteristics, diagnosis, treatment strategy and future perspectives.

Outcome Analysis of Treatment Modalities for Thoracic Sarcomas

Background: Primary chest wall sarcomas are a rare and heterogeneous group of chest wall tumors that require multimodal oncologic and surgical therapy. The aim of this study was to review our experience regarding the surgical treatment of chest wall sarcomas, evaluating the short- and long-term results. Methods: In this retrospective single-center study, patients who underwent surgery for soft tissue and bone sarcoma of the chest wall between 1999 and 2018 were included. We analyzed the oncologic and surgical outcomes of chest wall resections and reconstructions, assessing overall and recurrence-free survival and the associated clinical factors. Results: In total, 44 patients underwent chest wall resection for primary chest wall sarcoma, of which 18 (41%) received surgery only, 10 (23%) received additional chemoradiotherapy, 7% (3) received surgery with chemotherapy, and 30% (13) received radiotherapy in addition to surgery. No perioperative mortality occurred. Five-year overall survival was 51.5% (CI 95%: 36.1–73.4%), and median overall survival was 1973 days (CI 95% 1461; -). As determined in the univariate analysis, the presence of metastasis upon admission and tumor grade were significantly associated with shorter survival (p = 0.037 and p < 0.01, respectively). Five-year recurrence-free survival was 71.5% (95% CI 57.6%; 88.7%). Tumor resection margins and metastatic disease upon diagnosis were significantly associated with recurrence-free survival (p < 0.01 and p < 0.01, respectively). Conclusion: Surgical therapy is the cornerstone of the treatment of chest wall sarcomas and can be performed safely. Metastasis and high tumor grade have a negative influence on overall survival, while tumor margins and metastasis have a negative influence on local recurrence.

Shifting from a Biological-Agnostic Approach to a Molecular-Driven Strategy in Rare Cancers: Ewing Sarcoma Archetype.

Sarcomas of the thoracic cavity are rare entities that predominantly affect children and young adults. They can be very heterogeneous encompassing several different histological entities. Ewing Sarcoma (ES) can potentially arise from every bone, soft tissue, or visceral site in the body. However, it represents an extremely rare finding when it affects the thoracic cavity. It represents the second most frequent type of thoracic sarcoma, after chondrosarcoma. ES arises more frequently in sites that differ from the thoracic cavity, but it displays the same biological features and behavior of extra-thoracic ones. Current management of ES often requires a multidisciplinary treatment approach including surgery, radiotherapy, and systemic therapy, as it can guarantee local and distant disease control, at least transiently, although the long-term outcome remains poor. Unfortunately, due to the paucity of clinical trials purposely designed for this rare malignancy, there are no optimal strategies that can be used for disease recurrence. As a result of its complex biological features, ES might be suitable for emerging biology-based therapeutic strategies. However, a deeper understanding of the molecular mechanisms driving tumor growth and treatment resistance, including those related to oncogenic pathways, epigenetic landscape, and immune microenvironment, is necessary in order to develop new valid therapeutic opportunities. Here, we provide an overview of the most recent therapeutic advances for ES in both the preclinical and clinical settings. We performed a review of the current available literature and of the ongoing clinical trials focusing on new treatment strategies, after failure of conventional multimodal treatments.

Institutional experience of using active breathing control for paediatric and teenage patients receiving thoraco-abdominal radiotherapy

IntroductionActive Breathing Control (ABC) is a motion management strategy that facilitates reproducible breath-hold for thoracic radiotherapy (RT), which may reduce radiation dose to organs at risk (OARs). Reduction of radiation-induced toxicity is of high importance in younger patients. However, there is little published literature on the feasibility of ABC in this group. The purpose of this study was to report our experience of using ABC for paediatric and teenage patients. MethodsPatients ≤18 years referred for thoracic RT using ABC at our centre from 2013–2021 were identified. Electronic records were retrospectively reviewed to obtain information on diagnosis, RT dose and technique, OAR dosimetry, tolerability of ABC, post-treatment imaging and early toxicity rates. Results12 patients completed RT and were able to comply with ABC during planning and for the duration of RT. Median age was 15.5 years (10–18 years). Diagnoses were: Hodgkin lymphoma (n = 5), mediastinal B-cell lymphoma (n = 1), Ewing sarcoma (n = 5) and rhabdomyosarcoma (n = 1). For mediastinal RT cases (n = 6), median dose delivered was 30.6Gy(19.8–40Gy), median mean heart dose was 11.4Gy(4.8–19.4Gy), median mean lung dose was 9.9Gy(5.7–14.5Gy) and mean lung V20 was 10.9%. For ipsilateral RT cases, (n = 6), median hemithorax and total doses to primary tumour were 18Gy(15–20Gy) and 52.2Gy(36–60Gy) respectively. Median mean heart dose was 19.5Gy(10.6–33.2Gy) and median mean lung dose was 17.7Gy(16.3–30.5Gy). Mean bilateral lung V20 was 39.6%. Median mean contralateral lung dose was 5.2Gy(3.5–11.6Gy) and mean contralateral lung V20 was 1.5%. At a median follow-up of 36 months, only 1 patient had symptomatic radiation pneumonitis having received further thoracic RT following relapse. ConclusionsABC is feasible and well tolerated in younger patients receiving RT. Children as young as 10 years are able to comply. Use of ABC results in OAR dosimetry which is comparable to similar data in adults and can facilitate RT for extensive thoracic sarcoma

High-grade thoracic sarcoma with HMBOX1-ALK fusion: Case report

Under the nomination of soft tissue sarcomas there are a large variety of mesenchymal neoplasms. This group of rare entities is responsible for just 1 to 2%

Epirubicin, cisplatin plus ifosfamide versus standard chemotherapeutic regimens for advanced/unresectable primary thoracic sarcomas.

Thoracic sarcomas are rare malignancies, with limited data for unresectable/advanced scenarios. Our goal is to provide insights of a three-drug chemotherapy regimen improving patient survival compared to standard regimens. Retrospective cohort analysis of patients diagnosed with unresectable/advanced primary thoracic sarcoma divided between primary pulmonary sarcomas (PPS) and chest wall sarcomas (CWS) comparing chemotherapeutical regimens efficacy. Not true soft tissue sarcomas (STS) for PPS were excluded from the analysis. Univariate and multivariate analysis performed via Cox-regression model. Progression-free survival (PFS) and overall survival (OS) analysis via Kaplan-Meier with hazard ratio (HR) obtained via Mantel-Haenszel or log rank. 157 total cases were included, from which 50 cases were PPS and 107 cases CWS. For PPS, 4 cases were excluded from the analysis as they were not true STS. The most common histology was undifferentiated sarcomas, 63% of cases were treated with E/C/I and 37% with another regimen. The E/C/I regimen demonstrated a benefit for both OS (p = 0.020) and PFS (p = 0.010) when compared to any other regimen as well as when compared to non-platinum regimens (p = 0.016 and p = 0.001). Regarding CWS, the most common histology was synovial and undifferentiated sarcomas, 55.1% were treated with E/C/I and 44.9% treated with another regimen. The E/C/I regimen did not demonstrate a benefit for OS or PFS compared to any other regimen, neither when compared to other non-platinum regimens. However, a benefit was observed in favor of E/C/I when compared to other platinum regimens in both OS (p = 0.049) and PFS (0.015). Both analyses for PPS and CWS demonstrated a benefit in favor of cisplatin therapies compared to carboplatin in both OS and PFS. This study demonstrates that platinum therapy alone does not work, and that cisplatin must be the agent of choice and it's used in combination could increase treatment response. The E/C/I regimen demonstrated a in PPS but not for CWS, this is due do their rarity of PPS and that no standard treatment is established yet. The regimen proposed here could represent a possible new standard of treatment for PPS as long as it is validated in a prospective study.

Survival prognostic factors in unresectable/advanced primary thoracic sarcomas.

BackgroundPrimary thoracic sarcomas (PTS) including primary pulmonary and chest wall sarcomas (CWS), are aggressive lung malignancies with limited information specially in an advanced/unresectable setting. Unfortunately, prognostic factors for these malignancies are not well identified.MethodsRetrospective cohort analysis of patients diagnosed with unresectable/advanced soft tissue PTS from a third level reference institute. Univariate and multivariate analysis performed via Cox-regression model. Progression-free survival (PFS) and overall survival (OS) analysis via Kaplan-Meier method.ResultsA total of 157 patients were identified, 55.4% female, mean age 51.8 years (range, 18–90 years), 19.1% tobacco exposure and 10.8% asbestos exposure. The most common performance status was Eastern Cooperative Oncology Group (ECOG) 1 (38.9%), most common clinical presentation cough (58.4%) and thoracic pain (55.4%). Undifferentiated sarcoma (37.6%) followed by synovial sarcoma (34.4%) were the most common histologies. Most patients received five chemotherapeutic cycles (37.6%), 57.3% of patients obtained a partial response and 61.1% an overall response rate (ORR). Median PFS was 9 months [95% confidence interval (CI): 8.717–9.283 months]. The multivariable analysis identified ECOG ≥2, a poorer response to chemotherapy (less number of chemotherapy cycles) and an increase Response Evaluation Criteria in Solid Tumors (RECIST) to be associated with a shorter progression-free period. Median OS was 11 months (95% CI: 10.402–11.958 months) with an ECOG ≥2 and a poorer response to chemotherapy (less number of chemotherapy cycles) associated with a shorter survival.ConclusionsAge, gender, comorbidities, tobacco and asbestos exposure, clinical presentation and histopathological diagnosis are not useful prognostic factors in unresectable/advanced PTS, however, an adequate initial ECOG, RECIST and a better response to chemotherapy should be used as prognostic factors in the management of these tumors.

TH8.6 Thoracic sarcoma: three-year data from a tertiary referral centre

Abstract Aims The rarity of thoracic sarcomas leads to challenges in their diagnosis and evidence-based management. We aim to investigate the management and outcomes of primary thoracic sarcoma patients under the care of our tertiary centre Sarcoma Service over a three-year period. Methods Data of all thoracic sarcoma patients discussed at the tertiary centre multidisciplinary meetings from 2017–2019 were collected from the local electronic database. Results 65 patients met the inclusion criteria. The most common histological subtypes were chondrosarcomas and spindle cell sarcomas. 60% of cases were high-grade sarcomas. 14 out of 19 deaths occurred in patients with high grade sarcomas (p=0.0586). 78.3% of patients underwent surgical resection, with 35.4% undergoing surgical resection as their sole treatment modality. Surgical intervention was associated with a statistically significant improvement in survival (p < 0.0001*). Clear marginal status was associated with better survival outcomes (p = 0.026*). Local recurrence was seen in 15 cases, and 93.3% of these were in high-grade sarcomas. There was no association between recurrence and marginal status. 8 of the 15 cases with recurrence received surgical intervention for the recurrence. 4 of the cases with recurrence passed away within the study time frame. Conclusion Primary resection should remain the gold standard for treatment of thoracic sarcomas due to its significant improvement in survival. Variability between outcomes and overall survival is likely multifactorial – diversity of histological subtypes, predominance of high-grade sarcomas, and a wide range of age at diagnosis. Prospectively maintained databases and cross-centre collaboration would be beneficial for future study in thoracic sarcomas.

Thoracic Sarcoma: A New Glance at the Epidemiological Characteristics of Disease in Iran from 2009 to 2014.

Background:The heterogeneity, high rate of mortality and lack of comprehensive diagnostic methods have categorized primary sarcomas of the thorax as a malignancy with dismal outcomes and unknown etiology. Given the fundamental role of epidemiological analysis in establishing management strategies, we designed a study with focus on the epidemiological characteristics of primary thoracic sarcomas in Iran.Methods:This national population-based cancer study was conducted on patients with histologically confirmed sarcoma of the thorax referred to the Iranian National Cancer Registry between 2009 and 2014. The incidence was calculated as number of cases per 100,000 person-years and was age-adjusted by the direct method using the weight of the 1960 world standard population.Results:Over a 6-year period, 1477 cases with pathologically confirmed thoracic sarcomas were registered in Iran, of which 896 were male and 581 were female. Khuzestan Province had the highest incidence of thoracic sarcomas as compared to other provinces. Malignant mesothelioma was the most common histological subtype (20.85%). Moreover, the age-standardized incidence rate (ASR) of the disease was 1.94 per 100,000 which was more common in males than females with the highest incidence rate in men aged more than 65 years.Conclusion:Our study provided valuable epidemiologic data on characteristics of thoracic sarcomas. This data can be used for strategizing preventive measures.

Immune-Desert Tumor Microenvironment in Thoracic SMARCA4-Deficient Undifferentiated Tumors with Limited Efficacy of Immune Checkpoint Inhibitors.

BackgroundThoracic SMARCA4-deficient undifferentiated tumors (SMARCA4-UT) are aggressive neoplasms. Data linking BAF alterations with tumor microenvironment (TME) and efficacy of immune checkpoint inhibitors (ICI) are contradictory. The TME of SMARCA4-UT and their response to ICI are unknown.Materials and MethodsPatients diagnosed with SMARCA4-UT in our institution were included. Immunostainings for tertiary lymphoid structures (TLS), immune cell markers, and checkpoints were assessed. Validation was performed using an independent transcriptome dataset including SMARCA4-UT, non–small cell lung cancers (NSCLC) with/without SMARCA4 mutations, and unclassified thoracic sarcomas (UTS). CXCL9 and PD-L1 expressions were assessed in NSCLC and thoracic fibroblast cell lines, with/without SMARCA4 knockdown, treated with/without interferon gamma.ResultsNine patients were identified. All samples but one showed no TLS, consistent with an immune desert TME phenotype. Four patients received ICI as part of their treatment, but the only one who responded, had a tumor with a TLS and immune-rich TME. Unsupervised clustering of the validation cohort using immune cell scores identified 2 clusters associated with cell ontogeny and immunity (cluster 1 enriched for NSCLC independently of SMARCA4 status (n = 9/10; P = .001); cluster 2 enriched for SMARCA4-UT (n = 11/12; P = .005) and UTS (n = 5/5; P = .0005). SMARCA4 loss-of-function experiments revealed interferon-induced upregulation of CXCL9 and PD-L1 expression in the NSCLC cell line with no effect on the thoracic fibroblast cell line.ConclusionSMARCA4-UT mainly have an immune desert TME with limited efficacy to ICI. TME of SMARCA4-driven tumors varies according to the cell of origin questioning the interplay between BAF alterations, cell ontogeny and immunity.

Thorahcic SMARCA4-deficient undifferentiated tumors with ganglioneuroma and enchondroma: implications for SLC7A11 and ARID1A expression: a case report

BackgroundSWI/SNF-related, matrix-associated, actin-dependent regulator of chromatin, subfamily A, member 4-deficient thoracic sarcoma (SMARCA4-DTS) is a rare disease that has recently been described as an entity. It is characterized by an aggressive clinical course and specific genetic alterations. As an immunohistological feature, the tumors are deficient in SMARCA4 and SMARCA2 and express sex-determining region Y (SRY)-box 2 (SOX2). Occasionally, there are cases that are less frequent and difficult to distinguish from SMARCA4-deficient non-small cell lung carcinoma (SMARCA4-dNSCLC). Therefore, the 5th edition of the World Health Organization (WHO) classification describes thoracic SMARCA 4-deficient undifferentiated tumors (SMARCA4-UT). In contrast, Carney’s triad is a syndrome that combines three rare soft tissue tumors: gastric leiomyosarcoma, pulmonary chondroma, and extra-adrenal paraganglioma. Protein kinase cAMP-dependent type I regulatory subunit alpha (PRKAR1A) has been proposed as the causative gene. Both diseases are valuable cases; moreover, there have been no previous reports of their coexistence.Case presentationA 43-year-old man visited our hospital because of respiratory distress. Computed tomography revealed a large mass measuring 55 mm in the upper lobe of the right lung and front mediastinum, with metastases in the surrounding lymph nodes. Needle biopsy was performed for diagnosis, and histological examination of the samples revealed monotonous epithelioid-like cells with loose binding and sheet-form proliferation. The tumor cells had distinct nuclei with some rhabdoid-like cells. Immunohistochemical analysis revealed that the tumor cells were positive for AE1AE3, SOX2, CD34, and p53 and negative for SMARCA4 and SMARCA2. The patient died 6 months after admission, without any treatment. Autopsy revealed ganglioneuroma and enchondroma suggestive of an incomplete Carney complex.ConclusionSMARCA4-UT is a rare and recently established disease. While it is difficult to diagnose, it is necessary to distinguish undifferentiated carcinoma, large cell carcinoma, Ewing sarcoma, and epithelioid sarcoma when diagnosing tumors involving the mediastinum. Moreover, cases of SMARCA4-UT with ganglioneuroma and enchondroma are very rare. We discuss and report a case of SMARCA4-UT in which we also examined ARID1A and SLC7A11expression.

Treatment-Related Thoracic Soft Tissue Sarcomas in Two US Cohorts of Breast Cancer Survivors

Treatment-Related Thoracic Soft Tissue Sarcomas in Two US Cohorts of Breast Cancer Survivors

Health-Related Quality of Life Issues Experienced by Thoracic and Breast Sarcoma Patients: A Rare and Understudied Group.

Thoracic and breast sarcomas constitute a rare subgroup within the sarcoma population. There is limited knowledge about their health-related quality of life (HRQoL) and a valid disease-specific HRQoL instrument is lacking. This qualitative study aimed to investigate the HRQoL issues experienced by a small group of thoracic and breast sarcoma patients. Semi-structured interviews with 19 thoracic and four breast sarcoma patients were conducted and thematically analysed. Physical issues mentioned by both groups were fatigue, sleep disturbances, pain, wound infections, and symptoms related to chemotherapy and radiotherapy. Tightness in the back and restrictions in performing tasks above arm height were specific physical issues for breast sarcoma patients, whereas respiratory problems were only mentioned by thoracic sarcoma patients. Body image issues, changes in mood, fear of recurrence, and living with uncertainty were important mental health issues for both subgroups. Social issues in both groups included challenges in work and relationships, financial difficulties, loss of independence, and limitations in social activities. The identified physical, mental, and social health challenges can significantly impact thoracic and breast sarcoma patients’ HRQoL. Results of this qualitative study will guide personalised supportive care for breast and thoracic sarcoma patients and help in determining the best possible HRQoL measurement strategy for sarcoma patients with different primary sarcoma locations.

NUT carcinoma of the lung.

NUT carcinoma of the thorax is a rare and very aggressive tumor, whose definition is based on the demonstration of a nuclear protein in testis (NUTM1; also known as NUT) gene fusion on 15q14 with different partners from the bromodomain-containing proteins gene family. This fusion results in an activation of MYC oncoprotein responsible for the tumor's aggressivity. NUT carcinoma arises preferentially in young adults, presenting a large thoracic mass frequently associated with lymph nodes, bone or pleural metastases. At histology, this tumor is often poorly differentiated, mainly composed of sheets of small cells with scant cytoplasm, a round nucleus with a central nucleolus. Focal areas of squamous differentiation can be observed. Mitoses and necrosis are frequent, as well as neutrophilic infiltrate. The diagnosis is based on the detection of NUT protein expression by immunohistochemistry using the rabbit monoclonal antibody C52B1 in more than 50% of the tumor nuclei. This technique offers 87% sensitivity and nearly 100% specificity with reference to FISH or RT-PCR, which confirm the NUTM1 rearrangement. The differential diagnoses include basaloid carcinoma of the lung, small cell carcinoma, thymic carcinoma (basaloid variant), SMARCA4_deficient thoracic sarcoma, other NUTM1 rearranged undifferentiated tumors, small round cell tumors, non-Hodgkin lymphoma/leukemia, and melanoma. The prognosis of NUT carcinoma remains very poor, with a median survival of 6.7 months, and 1- and 2-year overall survival rates of 30% and 19%, respectively. NUT carcinoma is often refractory to conventional chemotherapy, but ifosfamide-based regimens or BET inhibitors could represent promising therapies.

SMARCA4/BRG1 protein-deficient thoracic tumors dictate re-examination of small biopsy reporting in non-small cell lung cancer.

BackgroundSMARCA4/BRG1 protein–deficient lung adenocarcinomas and thoracic sarcoma are recently described entities that lack distinctive histological features, transcription termination factor 1 (TTF1) reactivity, and actionable driver mutations. The current diagnostic path for small lung biopsies as recommended by the World Health Organization (WHO, 2015) is likely to categorize these as non–small cell carcinoma–not otherwise specified (NSCC-NOS). The present study attempts to define the subtle but distinctive clinicopathologic features of SMARCA4/BRG1 protein-deficient thoracic tumors; highlight their unique biology; and addresses the unmet need to segregate these using a new, tissue-proficient diagnostic pathway.MethodsAll lung biopsies and those from metastatic sites in patients with suspected advanced lung cancer and classified as NSCC-NOS as per WHO (2015) guidelines were subjected to BRG1 testing by immunohistochemistry. SMARCA4/BRG1 protein–deficient thoracic tumors were evaluated by an extended immunohistochemistry panel. Predictive biomarker and programmed death–ligand 1 testing was conducted in all cases.ResultsOf 110 cases, nine were found to be SMARCA4/BRG1 protein-deficient; six were identified as SMARCA4/BRG1 protein–deficient lung adenocarcinomas, and three were SMARCA4/BRG1 protein-deficient thoracic sarcomas. The histology ranged from poorly differentiated to undifferentiated to rhabdoid. None of the cases showed significant expression of TTF1 or p40, and no actionable mutation was identified.ConclusionsIt is difficult to separate BRG1-deficient lung adenocarcinomas and thoracic sarcomas based on morphology alone. We propose a diagnostic pathway for small biopsies of thoracic tumors to segregate these distinct entities so that they can be studied more efficaciously for new biomarkers and therapeutic options.

Immune-desert tumor microenvironment in SMARCA4-deficient thoracic sarcomas with limited efficacy of immune checkpoint inhibitors.

11552 Background: SMARCA4-deficient thoracic sarcomas (SDS) are rare and aggressive sarcomas characterized by inactivating SMARCA4 mutations, with no approved treatment to date. Previous data linking SWI/SNF deficiency with tumor immune microenvironment (TME) are contradictory. While an immunogenic microenvironment and efficacy of immune checkpoint inhibitors (ICI) were described in SMARCA4-deficient small cell carcinoma of the ovary, the TME phenotype of SDS is unknown; in addition, response of patients to ICI is lacking. Methods: All consecutive patients diagnosed with SDS between 2016 and 2019 in Strasbourg University Hospital were included and clinical outcomes collected. Immunostainings for immune cell markers, immune checkpoints and tertiary lymphoid structures (TLS) were assessed on available samples. Validation was performed using an independent transcriptomes dataset of SDS (n = 12), not otherwise specified (NOS) non-small cell lung cancer (NSCLC) with/without SMARCA4 mutations (n = 14) and undifferentiated thoracic sarcoma (n = 5). Finally, chemokines (CXL9 and CXCL10) and PD-L1 expressions were assessed in NSCLC and thoracic fibroblast cell lines, treated with/without interferon gamma (IFNG). Results: Nine patients were identified and had all metastatic disease at presentation, with a median overall survival of 1.8 months (0.3-NR). Among them, 4 received ICI as part of their treatment. Out of 11 evaluated tumors samples, all but one case showed no TLS, consistent with an immune desert TME phenotype charted by low densities of CD3+ T-cells, CD8+ T-cells, CD20+ B-cells from one side and high density of CD68+ macrophage-cells from the other side. Conversely, the unique tumor with TLS aggregate showed an immune-rich TME phenotype associated with high mutational tumor burden. While the patient with TLS harboring tumor showed an exceptional long-lasting response, the 3 remaining patients without TLS had progressive disease at best response to ICI. Using an independent cohort, unsupervised clustering using immune cell scores identified two clusters tightly associated with cell ontogeny of cancer subtypes and immunity; while cluster 1 (C1) was enriched for NOS NSCLC independently from SMARCA4 status (n = 9/10; 90%) (p = 0.001), C2 was enriched for SDS (n = 11/12; 91.7%) (p = 0.005) and undifferentiated thoracic sarcomas (n = 5/5; 100%) (p = 0.0005). Finally, SMARCA4 loss of function experiments revealed upregulation of chemokines (CXL9 and CXCL10) and PD-L1 expression in the NSCLC cell line with no effect on thoracic fibroblast cell line. Conclusions: SDS harbor an immune desert TME phenotype with limited efficacy to ICI, similar to other sarcomas. Our data suggest that TME of SMARCA4-driven tumors might vary according to the cell of origin. Further studies are needed to understand the interplay between SWI/SNF mutations, cell ontogeny and immunity.

SMARCA4-deficient thoracic sarcoma revealed by metastasis to the small intestine: a diagnostic dilemma

SMARCA4-deficient thoracic sarcoma (SMARCA4-DTS) is a recently identified aggressive subtype of sarcoma. We present the case of a 44-year-old man who underwent a surgery for a perforated small intestine. Compued tomography scan revealed a tissular mediastino–pulmonary mass.Histopathological examination of the intestinal mass shown a malignant tumour with a typical epithelioid and rhabdoid cells, numerous mitoses and large necrosis. A large panel of immunohistochemistry revealed loss of SMARCA4 and SMARCA2 and allowed the diagnosis of SMARCA4-DTS. It is important to consider SMARCA4-deficient thoracic sarcoma in the differential diagnosis of tumours showing suggestive morphologic features in patients of all ages, especially in the case of metastasis associated with thoracic mass.

P89.10 Genomic Alteration Features and Targeted Therapy Opportunities of Primary Thoracic Sarcoma Patients

Primary sarcomas of the thorax are rare, which may arise in the lung, mediastinum, pleura and chest wall. Studies of comprehensive molecular characteristics and targeted therapy opportunity in thoracic sarcoma patients are lacking. Formalin fixed, paraffin embedded (FFPE) tumor tissues and matched blood samples of 30 thoracic sarcoma patients were collected for 450 cancer gene targeted next-generation sequencing (NGS) assay in a College of American Pathologists (CAP) accredited and Clinical Laboratory Improvement Amendments (CLIA) certified laboratory. Genomic alterations and tumor mutational burden (TMB) values were assessed by next-generation sequencing assay with a mean coverage of 1000X, including single base substitution, short and long insertion/deletions, copy number variations, gene fusions and rearrangements. In total, tumor samples from 30 thoracic sarcoma patients were recruited, including 16 males and 14 females with a median age of 39 (range 11-67). This cohort of patient was comprised of seven undifferentiated pleomorphic sarcoma (UPS), four spindle cell sarcoma, three inflammatory myofibroblastic tumor (IMTs), three Ewing sarcoma (ES), three myxofibrosarcoma, two pulmonary artery sarcoma, two rhabdomyosarcoma, two fibrosarcoma, two angiosarcoma, one leiomyosarcoma and one epithelioid sarcoma. The most frequently mutated genes were TP53 (33%), ATRX (27%), CDKN2A (17%), NF1 (17%), PDGFRA (17%), CCND3 (13%) and CDKN2B (13%). Cases with TP53 alterations had lower age than wild type TP53 (35 vs. 62 years, respectively, P=0.0035). The median TMB of total patients was 1.5 muts/Mb. Twelve (40%) patients harbored at least one actionable genomic alteration, including ALK, PDGFB, ROS1 rearrangement, VEGFA, PDGFRA, KDR,KIT, FGFR1, FGFR3, CDK4 amplification and CDKN2A,CDKN2B deletion. Here, we identified two patients with pulmonary IMT harboring TFG-ROS1 fusion, who achieved continuous remission following treatment with crizotinib (Figure 1). Our study revealed that approximately 40% of patients with thoracic sarcoma harbored at least one druggable genomic alteration. A broader molecular testing, such as NGS, is necessary to explore the comprehensive genetic characteristics and potential drug targets for patients with thoracic sarcoma.