Integrase Interactor Research Articles

A rare case of pineoblastoma – Case report

Pineoblastoma is a very rare and aggressive malignant tumor of pineal gland. We report a case of 12-year-old male patient presented to S.V.P. tertiary care hospital with complain of progressive loss of vision in both eyes with nausea and headache. On examination bilateral upward gaze palsy was present. The magnetic resonance imaging report revealed possibility of pineal Germinoma. The patient underwent ventriculoperitoneal shunt insertion surgery for obstructive hydrocephalus and suboccipital craniectomy for tumor resection. The Histopathological examination report stated the tumor as Pineoblastoma, Grade IV. Immunohistochemistry studies were positive for synaptophysin and Integrase interactor-1 (INI-1) markers with high ki-67 labelling index and negative for CD-117 and Glial fibrillary acid protein (GFAP) markers. Microscopic and Immuno histochemisty findings are important to differentiate pineoblastoma from other pineal region tumors.

Atypical Teratoid/Rhabdoid Tumor with Retained SMARCB1 (INI1) Expression and Rare SMARCA4 Gene Mutation: A Case Report of a Pediatric Patient

Atypical teratoid/rhabdoid tumors (AT/RT) are highly aggressive tumors of the central nervous system (CNS), accounting for 1–3% of all pediatric CNS tumors. In general, AT/RTs are associated with biallelic inactivation of SMARCB1, resulting in the loss of expression of the integrase interactor 1 (INI1) protein. In this report, we describe the clinical course of an infant patient who presented with fatigue, postprandial vomiting, and disability of left side movement. Histological examination revealed classical features indicative of rhabdoid tumors, yet an atypical immunohistochemical profile with preserved INI1 expression was observed. Molecular diagnostics further elucidated the presence of a heterozygous frameshift variant, SMARCA4 c.2693del, p.(Asn898Thrfs*12), underscoring the distinctive genetic foundations of the case. Surgical resection of the tumor was administered with subsequent chemotherapy to the patient, but the condition worsened dynamically, and a decision was made to give the patient palliative therapy. We report on a patient with AT/RT caused by a rare mutation of the SMARCA4 gene and an aggressive course of disease to provide more information and characteristics of these tumors.

Efficacy of immune checkpoint inhibitors in SMARCA4-deficient and TP53 mutant undifferentiated lung cancer.

The present study was conducted to characterize the clinicopathologic characteristics, immunohistochemical staining results, and immune checkpoint inhibitors (ICIs) efficacy in patients with SMARCA4-deficient/TP53 mutant lung cancer. Patients diagnosed with advanced or metastatic undifferentiated lung cancer harboring SMARCA4-deficient and TP53 mutations, however, without targetable sensitive mutations were retrieved from the electronic medical record system. Descriptive statistics were used to describe the baseline characteristics and clinical features including age, gender, eastern cooperative oncology group performance status, disease stage, smoking status, chief complaint, site of the primary mass, tumor size, gross type, symptoms, local invasion, and metastatic sizes. Immunological markers and potential drive genes were detected by immunohistochemical staining and next generation sequencing. Efficacy and safety profile of ICIs in included patients was evaluated with progression-free survival and overall survival. Between January 2019 and September 2022, there were 4 patients included within the inclusion criteria in the present study. Biomarkers including CK, CK7, and integrase interactor 1 were detected positive, however, other immunological markers including CK20, CD56, P63, P40, NapsinA, TTF-1, CgA, Syn, BRG1, or PD-L1 were detected negative among them. Results of next generation sequencing panel were failed to discover any targetable sensitive mutations. A total of 4 mutation types of TP53, including p.C141Y, p.S240G, p.E339X (terminator acquired), and p.L130F detected for the patients, respectively. Microsatellite stability status, as well as low tumor mutation burden was identified among all the patients. Median progression-free survival for ICIs as first line treatment and median overall survival were 3.25 months (range from 1.3 to 6.8 months), and 6.0 months (range from 2.7 to 9.6 months), respectively. Our results indicated that advanced lung cancer patients harboring co-occurring SMARCA4-deficient/TP53 mutations might respond to ICIs treatment, though within negative programmed cell death-ligand 1 expression or low tumor mutation burden. However, hyperprogressive disease by ICIs may also happen for such patients. The mutation types of TP53 might play a role during the exposure of ICIs, however, need further identification in basic experiments.

SMARCB1-Deficient Sinonasal Carcinoma–A Case Report and Literature Review

Switch/sucrose non-fermentable-related matrix-associated actin-dependent regulator of chromatin subfamily B member 1 (SMARCB1)-deficient sinonasal carcinoma is a rare subtype of sinonasal undifferentiated carcinoma (SNUC). Due to the highly aggressive nature of the disease course, it is important to diagnose early and use multimodal treatments in the course of the disease. Two main morphologic patterns are commonly identified under the microscope: plasmacytoid/rhabdoid and basaloid. Furthermore, it demonstrates a total absence of integrase interactor 1 expression upon immunohistochemical staining. Here, we present two cases of SMARCB1-deficient sinonasal carcinoma with contrasting outcomes.

Characterization of Switch/Sucrose Nonfermenting Complex Proteins and Nestin Expression in a Cohort of Pediatric Central Nervous System Tumors.

Tumors of the central nervous system (CNS) in pediatric patients have undergone significant diagnostic refinement through the use of immunohistochemistry (IHC) and molecular techniques. The utility of these novel IHC antibodies has been demonstrated with the inactivation of the switch/sucrose nonfermenting (SWI/SNF) chromatin-remodeling complex in the diagnosis of atypical teratoid/rhabdoid tumors, predominantly through the loss of integrase interactor 1 (INI1; SMARCB1 ). Alternatively, these tumors may have inactivation of brahma-related gene 1 (BRG1; SMARCA4 ) in a subset of cases. The role of other SWI/SNF component proteins and their expression in pediatric brain tumors is not well established. Nestin, an intermediate filament, has been shown to be present in some pediatric CNS tumors, but of uncertain diagnostic and prognostic significance. We sought to explore the immunohistochemical expression profile for common SWI/SNF subunits and nestin in a pediatric CNS tumor cohort. Using a 118-sample tissue microarray, we performed IHC for INI1, BRG1, brahma (BRM), ARID1A, ARID1B, polybromo 1, and nestin. In 19 cases, INI1 was lost and BRG1 was lost in 2 cases. Interestingly, 6 cases originally diagnosed as primitive neuroectodermal tumors showed isolated loss of BRM. Other SWI/SNF proteins did not provide further diagnostic resolution. Nestin was positive in 76.2% of INI1/BRG1-deficient tumors, compared with 29.1% in INI1/BRG1-intact tumors yielding a sensitivity of 76.2%, specificity of 68.0%, and a P value of <0.001, but nestin positivity did not correlate specifically with poor outcomes. In conclusion, we confirm the utility of BRG1 IHC in the workup of pediatric CNS tumors, which may facilitate a difficult diagnosis when conventional markers are inconclusive, or as a first-line marker in cases where intraoperative smears are suggestive of atypical teratoid/rhabdoid tumor. Although nestin expression was associated with SWI/SNF inactivation, it did not yield statistically significant diagnostic or prognostic information in our study. Interestingly, we identified 6 tumors with isolated BRM IHC loss, the significance of which is uncertain but warrants further investigation.

Exiguous and Scarce-SMARCB1 Deficient Medullary Renal Cell Carcinoma

Switch / sucrose non fermentable (SWI/SNF) related, matrix associated, actin dependent regulator of chromatin subfamily B member 1 (SMARCB1) deficient medullary renal cell carcinoma is an exceptionally discerned, aggressive carcinoma associated with deficiency of SMARCB1 or integrase interactor 1(INI1).

Gum Arabic nanoformulation rescues neuronal lesions in bromobenzene-challenged rats by its antioxidant, anti-apoptotic and cytoprotective potentials

Bromobenzene (BB) is a hazardous environmental contaminant because of its multiple routes of exposure and the toxicity of its bio-derivates. It could elicit neuronal alterations by stimulating redox imbalance and apoptotic pathways. Gum Arabic (GA) protected the hippocampus of a type 2 diabetic rat model from cognitive decline. Whether gum Arabic nanoemulsion (GANE) can increase the neuroprotectant potency of GA in fighting BB-associated neurological lesions is the question to be answered. To accomplish this objective, 25 adult male Wistar rats were randomly and equally assigned into five groups. Control received olive oil (vehicle of BB). BB group received BB at a dose of 460mg/kg BW. Blank nanoemulsion (BNE) group supplemented with BNE at 2mL of 10% w/v aqueous suspension/kg BW. GANE group received GANE at a dose of 2mL of 10% w/v aqueous suspension/kg BW. BB + GANE group exposed to BB in concomitant with GANE at the same previous doses. All interventions were carried out daily by oral gavage for ten consecutive days. BB caused a marked increase in malondialdehyde and succinate dehydrogenase together with a marked decrease in reduced glutathione, glutathione peroxidase, glutathione reductase, superoxide dismutase, catalase, and lactate dehydrogenase in the brain. BB was accompanied by pathological deteriorations, amyloidosis, and reduced immuno-expression of integrase interactor 1 in the hippocampal region. Administration of GANE was beneficial in reversing the aforementioned abnormalities. These results pave the road for further discovery of nano-formulated natural products to counter the threats of BB.

Analysis of 18 cases of malignant rhabdoid tumor in children

Objective: To investigate the clinical characteristics, treatment and prognosis of malignant rhabdoid tumor (MRT) in children. Methods: Clinical data total of 18 children with MRT treated in the Department of Hematology and Oncology, Children's Hospital, the First Affiliated Hospital of Zhengzhou University between June 2015 to June 2021 were analyzed retrospectively. The patients were grouped according to age, gender, tumor type, clinical stage and other factors.Progression free survival (PFS) and overall survival (OS) were calculated by Kaplan-Meier method, survival differences among different groups were compared by Log-rank test, and prognostic factors were analyzed by Cox regression model. Results: Among the 18 patients, there were 5 males and 13 females. The age of disease onset was 30.5 (12.0, 75.0) months, the tumor diameter was (80±29) mm, and no integrase interactor 1 (INI-1) expression was detected by immunohistochemistry. There were 7 cases of malignant rhabdoid tumor of the kidney (MRTK), 6 cases of atypical teratoid rhabdoid tumor (ATRT) and 5 cases of extrarenal extracranial rhabdoid tumor (EERT). At the time of early diagnosis, 12 patients were clinically stage Ⅲ-Ⅳ, 11 patients had local or distant metastasis, and 4 patients had metastasis during treatment. Surgical excision is the preferred treatment. There were 3 cases with preoperative puncture biopsy, 13 cases with complete resection, 4 cases with partial resection, and 1 case without operation. Thirteen patients were treated with the domestic conventional chemotherapy regimen for Wilms' tumor, medulloblastoma and rhabdomyosarcoma, and 5 patients were treated with the international conventional chemotherapy regimen. Nine patients received radiotherapy, including 1 case of MRTK, 4 cases of ATRT and 4 cases of EERT. By the end of follow-up in January 2022, 7 patients survived and 11 patients died. The 3-year PFS and OS rates were (8±8) % and (14±12) %. Log-rank test showed that the 5-year OS of EERT group was higher than ATRT and MRTK groups (χ²=16.31, P<0.001), the tumor diameter <80 mm group was higher than that of the ≥80 mm group (χ²=4.49, P=0.034), and the radiotherapy group was higher than no radiotherapy group (χ²=3.97, P=0.046). The differences were statistically significant. There was no significant difference in the influence of tumor type, age, tumor diameter, radiotherapy and chemotherapy on OS by Cox regression model (all P>0.05). Log-rank test showed that the 3-year PFS of EERT group was higher than ATRT and MRTK groups (χ²=11.14, P=0.004),>3 years group was higher than ≤3 years group (χ²=10.10, P=0.001), the differences were statistically significant. Tumor type, clinical stage, tumor diameter, age, tumor rupture and radiotherapy were included in the Cox regression model, and the results showed that clinical stage (HR=0.49, 95%CI 0.26-0.94, P=0.031), tumor diameter (HR=8.67, 95%CI 1.84-40.89, P=0.006), age (HR=0.01, 95%CI 0.00-0.15, P=0.001) had statistical significance on PFS. Conclusions: MRT is one of the most aggressive and fatal cancers in early childhood and infancy. There is no standard treatment and the prognosis is extremely poor. Clinical stage, tumor size and age are risk factors for disease progression.

Commentary on: SMARCB1 as a novel diagnostic and prognostic biomarker for osteosarcoma.

In the last couple of decades, biomarkers have been on the rise for diagnostic and predictive value. There has been a rush to identify new markers using new technologies and drug repurposing approaches. SMARCB1 acronym arises from the SWI/SNF (SWItch/Sucrose Non-Fermentable)-related Matrix-associated Actin-dependent Regulator of Chromatin subfamily B member 1 (SMARCB1). It is a molecule, whose role is associated with the sucrose metabolism. SMARCB1 is also called INI1 (Integrase Interactor 1). The molecule was discovered in the mid-1990s. Its role as a loss-of-function marker for malignant rhabdoid tumors (MRT) of renal and extrarenal origin has enormously expanded the spectrum of involved neoplasms since that time. Several tumors have been characterized by genetic aberrations in the SMARCB1 gene. They include reduction in expression, loss of expression, and mosaic expression. Most of the tumors are sarcomas, but a variegated group of tumors with mixed phenotypes has also been delineated. It is well known that the outcome of patients harboring genetic aberrations in the SMARCB1 gene has been poor. Guo et al. reported that reduced SMARCB1 expression occurred in 70% of osteosarcomas. Their data significantly correlated with poor neoadjuvant response. These authors emphasize a shorter progression-free and overall survival of the patients demonstrating an altered expression of this gene. Interestingly, mRNA in silico analysis established that SMARCB1 expression correlates with the response to chemotherapy of osteosarcoma patients, but there was no reliable correlation between SMARCB1 expression level and metastasis, response to neoadjuvant therapy, overall survival, and progression-free survival. The study involved a tissue microarray (TMA) on bone tumors that may limit the full evaluation of the gene expression. Nevertheless, Guo et al.’s study is remarkable. It expands the list of the tumors harboring an altered SMARCB1 gene expression and suggests that this marker should be investigated in every pathology workup for potential predictive value. On the other side, much work needs to be done if we hope that we strive to provide additional therapeutic strategies for osteosarcoma patients with altered SMARCB1 gene expression.

Update on phase 1 study of tazemetostat, an enhancer of zeste homolog 2 inhibitor, in pediatric patients with relapsed or refractory integrase interactor 1–negative tumors.

10040 Background: A defining feature of malignant rhabdoid tumors (MRTs), epithelioid sarcoma (ES), and poorly differentiated chordomas (PDC) is loss of integrase interactor 1 (INI1) expression, which induces dependence on enhancer of zeste homolog 2 (EZH2). Tazemetostat (TAZ) is a selective EZH2 inhibitor approved by the US Food and Drug Administration for patients (pts) aged ≥16 y with metastatic or locally advanced ES ineligible for complete resection. Pediatric dose escalation and interim efficacy and safety data for the dose expansion were previously reported. Updated efficacy, safety, subgroup analyses, and translational results are reported here. Methods: NCT02601937 is a phase 1 multicenter study evaluating TAZ monotherapy ≤2400 mg/m2 daily in pediatric pts with relapsed or refractory INI1− tumors (MRT, atypical teratoid rhabdoid tumor [ATRT], select tumors with rhabdoid features, other INI1− tumors, and SS18-SSX synovial sarcoma). Primary endpoint for dose expansion was objective response rate (ORR). Secondary endpoints included safety/tolerability, duration of response (DOR), progression-free survival (PFS), and overall survival. Selected exploratory flow data using 250,000 cells from peripheral blood were available for up to 25 pts. Results: Phase 1 enrolled 109 pts (escalation, n=46; expansion, n=63; Table) with mean ages of 5.4 y in the dose escalation and 7.4 y in the dose expansion. ORRs were 7% (3/46) in the dose escalation and 14% (9/63) in the dose expansion. Per tumor category in the dose expansion, ORRs were 24% (5/21) ATRT, 33% (2/6) PDC, 22% (2/9) ES, and 0% in non–CNS RTs (n=21) and other tumors (n=6). ORR for pts with prior radiotherapy was 14% (11/80) vs 3% (1/29) with prior radiotherapy ( P&gt;0.05). In the dose expansion, median PFS was 8 wk (95% CI: 8–13), OS was 21 wk (95% CI: 13–38), and DOR was 35 wk (95% CI: 24–121). Grade 3–4 treatment-related treatment-emergent adverse event rates were 15% (7/46) in the dose escalation and 22% (14/63) in dose expansion. Differences between responders (R) and nonresponders (NR) at C1D1 for neutrophil counts were significant ( P&lt;0.05). All R (6/6) had &lt;125,000 total neutrophils at C1D1 vs 42% (8/19) of NR; 50% (3/6) of R had &gt;50,000 total CD3 T cells vs 0% (0/19) of NR. Conclusions: TAZ showed promising antitumor activity in ATRT, ES, and PDC. Potential synergism between prior radiotherapy and TAZ requires further investigation. TAZ was generally well tolerated. The biological/clinical significance of differences in peripheral blood cell counts between R and NR at C1D1 needs further investigation. Clinical trial information: NCT02601937. [Table: see text]

Establishment of Organoids From Human Epithelioid Sarcoma With the Air-Liquid Interface Organoid Cultures

BackgroundAlthough biological resources are essential for basic and preclinical research in the oncological field, those of sarcoma are not sufficient for rapid development of the treatment. So far, some sarcoma cell lines have been established, however, the success rate was low and the established sarcoma types were frequently biased. Therefore, an efficient culture method is needed to determine the various types of sarcomas. Organoid culture is a 3-dimentional culture method that enables the recapitulation of the tumor microenvironment and the success rate reported is higher than the 2-dimentional culture. The purpose of this study was to report our newly established organoids from human epithelioid sarcoma using the air-liquid interface organoid culture method.MethodsWe treated 2 patients with epithelioid sarcoma in our institute. The remaining sarcoma specimens after surgical resection were embedded in collagen type 1 gels according to the air-liquid interface organoid culture method. After serial passages, we xenografted the organoids to NOD-scid IL2Rgnull (NSG) mice. Using the developed tumors, we performed histological and genomic analyses to compare the similarities and differences with the original epithelioid sarcoma from the patient.ResultsOrganoids from the epithelioid sarcoma could be serially cultured and maintained in collagen type 1 gels for more than 3 passages. Developed orthotopic tumor xenografts were detected in the NSG mice. After the process was repeated severally, the patient derived organoid lines from the epithelioid sarcoma were established. The established organoids showed loss of integrase interactor 1 expression with polymerase chain reaction and immunohistochemical analyses. The xenografted organoids of the epithelioid sarcoma had histologically similar phenotypes with the original tumor and genetically resembled it to some degree.ConclusionsThe present study demonstrated 2 novel established organoid models of epithelioid sarcoma, and our organoid models could be used to investigate the molecular pathogenesis and develop a novel treatment.

Painful, erythematous, and ulcerated nodules on the thigh

A 27-year-old man with no significant past medical history presented due to concern for bumps on his leg that had persisted for several months. On physical examination, multiple firm pink nodules ranging from 1 to 3 cm were observed on the lateral aspect of the left thigh, some of which were ulcerated (Fig 1). An excisional biopsy was performed, which revealed spindled-to-epithelioid cells with infiltrative borders and focal neutrophilic infiltrate (Fig 2). The lesional cells stained for pancytokeratin (AE1/AE3), CD31, ETS-related gene (ERG), and integrase interactor 1 (INI1), and were negative for CD34, S100, and factor XIIIa (Fig 3).

Clinical Diagnosis and Treatment Analyses on SMARCB1 (Integrase Interactor 1)–Deficient Sinonasal Carcinoma: Case Series with Systematic Review of the Literature

This study aims to improve the understanding of SMARCB1 (integrase interactor 1)-deficient sinonasal carcinoma (SDSC) by analyzing its clinical features, treatment strategies, and prognosis. Sixty-nine patients were included in this research: 15 new cases from Beijing Tongren Hospital and 54 previously reported cases. We analyzed and summarized patients' epidemiologic data, clinical features, and treatment regimens. Main outcomes were overall survival (OS) and recurrence-free survival (RFS). Univariate and multivariate analyses were performed using a Cox regression model for OS and RFS. SDSC was more common in men than women with a median age of 52 years (range, 21-89 years). Epistaxis (40.0%) and headache (36.7%) were the major symptoms. The most common affected paranasal sinus was the ethmoid sinus (58.0%). For TNM stage, 66.7% cases were first diagnosed as T4N0M0. The tumor cells were complete loss of integrase interactor 1 in all cases by immunohistochemical analysis. However, 72.5% patients were first misdiagnosed initially. The 1-year, 3-year, and 5-year OS and RFS were 85.3%, 51.8%, 47.8%; and 56.8%, 38.2%, and 35.3%, respectively. The RFS of comprehensive treatment based on surgery was better than that of systemic therapy without surgery (P < 0.05). In addition, the OS and RFS of surgery with chemoradiotherapy was better than that of surgery with radiotherapy (P < 0.05). Univariate and multivariate analysis identified treatment modality as an independent prognostic factor for patients with SDSC. Immunohistochemical analysis of SDSC during initial biopsy can prevent delays in diagnosis and treatment. Radical surgery resection combined with chemoradiotherapy may be the preferred treatment modality.

Brahma-related gene 1 has time-specific roles during brain and eye development.

During development, gene expression is tightly controlled to facilitate the generation of the diverse cell types that form the central nervous system. Brahma-related gene 1 (Brg1, also known as Smarca4) is the catalytic subunit of the SWItch/sucrose nonfermentable (SWI/SNF) chromatin remodeling complex that regulates transcription. We investigated the role of Brg1 between embryonic day 6.5 (E6.5) and E14.5 in Sox2-positive neural stem cells (NSCs). Being without major consequences at E6.5 and E14.5, loss of Brg1 between E7.5 and E12.5 resulted in the formation of rosette-like structures in the subventricular zone, as well as morphological alterations and enlargement of neural retina (NR). Additionally, Brg1-deficient cells showed decreased survival in vitro and in vivo. Furthermore, we uncovered distinct changes in gene expression upon Brg1 loss, pointing towards impaired neuron functions, especially those involving synaptic communication and altered composition of the extracellular matrix. Comparison with mice deficient for integrase interactor 1 (Ini1, also known as Smarcb1) revealed that the enlarged NR was Brg1 specific and was not caused by a general dysfunction of the SWI/SNF complex. These results suggest a crucial role for Brg1 in NSCs during brain and eye development.

INI1-negative colorectal undifferentiated carcinoma with rhabdoid features and postoperative rapidly growing liver metastases: a case report and review of the literature

BackgroundMalignant tumors with rhabdoid features are extremely rare. They can occur in various organs, including the gastrointestinal tract, with common clinical features of high malignancy and poor prognosis.Case presentationA 41-year-old man visited our hospital complaining of lower abdominal pain and fever. Computed tomography (CT) revealed two wall-thickening lesions in the rectum and sigmoid colon, with the latter invading the small intestine and abdominal wall. Lymph nodes were swollen in the sigmoid mesocolon and at the roots of the inferior mesenteric artery. Colonoscopy revealed a circular type 3 lesion in the sigmoid colon and a semicircular type 2 lesion in the rectum. Biopsies of the sigmoid colon and rectum lesions revealed poorly and moderately differentiated adenocarcinoma cells, respectively. The sigmoid colon, rectum, invaded small intestine, and abdominal wall were resected; lymph node dissection was also performed. Histopathological finding of the sigmoid colon lesion revealed that the tumor cells had poor connectivity with each other, and each cell had eosinophilic cytoplasm and a polymorphic nucleus. These characteristics are termed rhabdoid features, because the morphology of these cells is similar to that of rhabdomyosarcoma tumor cells. Immunohistochemical examination showed that the tumor cells were positive for both epithelial (cytokeratin AE1/AE3) and mesenchymal cell markers (vimentin); however, they were negative for integrase interactor 1 (INI1). Therefore, the sigmoid colorectal cancer was diagnosed as an INI1-negative undifferentiated carcinoma with rhabdoid features. The patient continued to experience high fever after surgery; thus, we performed an abdominal CT scan that revealed cystic lesions in the liver 4 days after surgery. These were absent in the positron emission tomography (PET)-CT scan performed 14 days before surgery. These tumors grew rapidly, and fine needle aspiration cytology revealed that they were undifferentiated carcinomas compatible with metastatic lesions from the undifferentiated carcinoma with rhabdoid features from the sigmoid colon. Chemotherapy was administered but was not effective. The patient died 60 days after surgery.ConclusionsINI1-negative colorectal undifferentiated carcinomas with rhabdoid features are extremely rare, have high histological malignancy, and a poor prognosis. Chemotherapy is not effective. Effective systemic therapy is desired.

The Novel Histone Deacetylase Inhibitor, OBP-801, Induces Apoptosis in Rhabdoid Tumors by Releasing the Silencing of NOXA.

Rhabdoid tumor is an aggressive, early childhood tumor. Biallelic inactivation of the SWI/SNF-related matrix-associated actin-dependent regulator of chromatin subfamily B member 1 (SMARCB1)/integrase interactor 1 (INI1) gene is the only common genetic feature in rhabdoid tumors. Loss of SMARCB1 function results in downregulation of several tumor suppressor genes including p16, p21, and NOXA The novel histone deacetylase inhibitor, OBP-801, induces p21 and has shown efficacy against various cancers. In our study, OBP-801 strongly inhibited the cell growth of all rhabdoid tumor cell lines in WST-8 assay. However, Western blotting and cell-cycle analysis revealed that OBP-801 did not activate the P21-RB pathway in some cell lines. p21 knockout indicated that p21 did not dominate the OBP-801 antitumor effect in rhabdoid tumor cell lines. We discovered that OBP-801 induced NOXA expression and caspase-dependent apoptosis in rhabdoid tumor cell lines independent of TP53. Chromatin immunoprecipitation assay showed that OBP-801 acetylated histone proteins and recruited RNA polymerase II to the transcription start site (TSS) of the NOXA promotor. Moreover, OBP-801 recruited BRG1 and BAF155, which are members of the SWI/SNF complex, to the TSS of the NOXA promotor. These results suggest that OBP-801 epigenetically releases the silencing of NOXA and induces apoptosis in rhabdoid tumors. OBP-801 strongly inhibited tumor growth in human rhabdoid tumor xenograft mouse models in vivo Terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling and cleaved caspase-3 were stained in tumors treated with OBP-801. In conclusion, OBP-801 induces apoptosis in rhabdoid tumor cells by epigenetically releasing the silencing of NOXA, which is a key mediator of rhabdoid tumor apoptosis. The epigenetic approach for NOXA silencing with OBP-801 is promising for rhabdoid tumor treatment.

Epithelioid Sarcoma-From Genetics to Clinical Practice.

Epithelioid sarcoma is a mesenchymal soft tissue sarcoma often arising in the extremities, usually in young adults with a pick of incidence at 35 years of age. Epithelioid sarcoma (ES) is characterized by the loss of SMARCB1/INI1 (integrase interactor 1) or other proteins of the SWI/SNF complex. Two distinct types, proximal and distal, with varying biology and treatment outcomes, are distinguished. ES is known for aggressive behavior, including a high recurrence rate and regional lymph node metastases. An optimal long-term management strategy is still to be defined. The best treatment of localized ES is wide surgical resection. Neo-adjuvant or adjuvant radiotherapy may be recommended, as it reduces the local recurrence rate. Sentinel lymph node biopsy should be considered in ES patients. Patients with metastatic ES have a poor prognosis with an expected median overall survival of about a year. Doxorubicin-based regimens are recommended for advanced ES. Tazemetostat, an EZH2 methyltransferase, has shown promising results in ES patients. Novel therapies, including immunotherapy, are still needed.

Phase I study of tazemetostat, an enhancer of zeste homolog-2 inhibitor, in pediatric pts with relapsed/refractory integrase interactor 1-negative tumors.

10525 Background: Absence of integrase interactor 1 (INI1) expression is a defining molecular feature of rhabdoid tumors (RT), epithelioid sarcoma (ES), and chordomas, inducing dependence on enhancer of zeste homolog-2 (EZH2). Tazemetostat (TAZ) is a selective EZH2 inhibitor approved by the FDA for treatment of patients (pts) ≥16 yrs with metastatic or locally advanced ES ineligible for complete resection. Data from a Phase 1 (Ph1) pediatric dose-escalation study (Ph1a) of TAZ were previously reported; herein we report interim efficacy and safety from the Ph1 pediatric dose-expansion study (Ph1b). Methods: NCT02601937 is a Ph1, multicenter study in pts 6 months – 18 yrs evaluating TAZ administered BID at 1200 mg/m2 in Ph1b, per Ph1a recommendation. Ph1b cohorts enrolled pts based on tumor type: Atypical teratoid RT (ATRT), RT, and other INI1-negative tumors (including ES and chordoma). The Ph1b primary endpoint was overall response rate (ORR). Secondary endpoints included safety/tolerability, duration of response (DOR), and survival. Results: Ph1b has enrolled 47 pts who received TAZ oral suspension. Across all tumor types, ORR was 17% (Table). Responses were observed in ATRT (4/21), chordoma (2/4), and ES (2/7); 1 pt dosed at 520mg/m2 and 7pts at 1200mg/m2. In the ATRT cohort, 19% of pts responded to TAZ with a median DOR of 6.5 months. The median DOR has not yet been reached in the other cohorts, with ongoing responses in 3 pts. TAZ was generally well tolerated with no drug-related deaths. Most common adverse events (AE) include vomiting, nausea, and cough. During Ph1b enrollment, 1 pt with chordoma (dosed at TAZ 900 mg/m2 for 15 months in Ph1a) developed a secondary malignancy (T-cell lymphoblastic lymphoma). In response, the pediatric recommended Ph2 dose was revised to limit exposure in pts without CNS involvement to 520 mg/m2 TAZ (maximum dosing of 1 yr after response, pts to go off-treatment until disease progression). Conclusions: Interim results indicate TAZ is generally well tolerated in children with an AE profile similar to adults. Pt enrollment in the non-ATRT, INI1-negative cohorts is ongoing. TAZ shows promising anti-tumor activity in a subset of pediatric tumors, including ATRT, chordoma, and ES. Clinical trial information: NCT02601937. [Table: see text]

MON-262 A Case of the Suprasellar Atypical Teratoid Rhabdoid Tumor (ATRT) Presenting in an Adult Treated with Intrathecal Chemotherapy

Background: Atypical teratoid rhabdoid tumors (ATRTs) are highly malignant tumors that usually present as a posterior fossa mass in children less than 3 years old. Only 38 cases have been reported in adults. They are also typically located in the supratentorial region. In none of the reported cases of suprasellar ATRT in the adult, intrathecal chemotherapy (via ommaya) has been used. Clinical case: A 70-year-old woman presented with a severe headache and magnetic resonance imaging (MRI) revealed a suprasellar mass measuring 2.9 x 2.1 x 3.0 cm. Shortly after her presentation, she developed an acute 3rd nerve palsy, and repeat MRI found dramatic interval growth. A transsphenoidal approach for biopsy/resection was attempted, but the lesion was not accessible via this corridor. She then underwent a right frontotemporal craniotomy and subsequently developed panhypopituitarism, including diabetes insipidus. Pathology revealed poorly differentiated malignant cells. Immunohistochemistry was positive for synaptophysin, Epithelial Membrane Antigen (EMA), Tumor protein p53, and negative for integrase interactor 1 (INI-1 antibody) with loss of expression in tumor nuclei with positive internal control in endothelial cells. These findings confirmed the diagnosis of ATRT. The Ki-67 index was 60% consistent with a highly proliferative tumor. One month later, she developed acute mental status change. Repeat computed tomography, and MRI showed recurrence of the tumor at the same location with new leptomeningeal enhancement involving the left facial nerve. Multimodal treatment was instituted, consisting of intraventricular/intrathecal chemotherapy with etoposide and topotecan plus fractionated external beam cranial irradiation (30 Gy in 10 fractions). She continued to deteriorate, and following consultation with her family, she was transferred to hospice care and died six months following her initial surgery. Conclusion: This is the first case of adult suprasellar ATRT that has been treated with intrathecal chemotherapy. There is no consensus on the best combination of chemotherapy, and often the St. Jude’s protocol used in the treatment of pediatric ATRT is used. In line with the biological behavior reported for this tumor in children and adults in different locations, the tumor was very aggressive, resulting in the patient’s death only after 6 months from the diagnosis despite aggressive surgical and medical treatment. Reference: 1. Athale, U. H., J. Duckworth, I. Odame, and R. Barr. 2009. Childhood atypical teratoid rhabdoid tumor of the central nervous system: a meta‐analysis of observational studies. J. Pediatr. Hematol. Oncol. 31:651-663. 2. Shonka N, Armstrong T (2011) Atypical teratoid/rhabdoid tumors in adults: A case report and treatment-focused review. J Clin Med Res 3: 85-92.

Loss of Integrase Interactor 1 (INI1) Expression in a Subset of Differentiated Thyroid Cancer

Alterations in the switching defective/sucrose non-fermenting (SWI/SNF) chromatin-remodeling complex are enriched in advanced thyroid cancer. Integrase interactor 1 (INI1), encoded by the SMARCB1 gene on the long arm of chromosome 22, is one of the core subunits of the SWI/SNF complex. INI1 immunohistochemistry is frequently used for the diagnosis of malignant rhabdoid neoplasms. In the present study, we found normal and benign thyroid tissues generally had diffusely intense nuclear immunostaining. Loss of INI1 immunohistochemical expression was observed in 8% of papillary thyroid cancer and 30% of follicular thyroid cancer. Furthermore, loss of INI1 expression was associated with extrathyroidal extension (p < 0.001) and lymph node metastasis (p = 0.038). Analysis of The Cancer Genome Atlas database revealed that SMARCB1 underexpression was associated with the follicular variant subtype and aneuploidy in papillary thyroid cancer. We speculate that SMARCB1 is an important effector in addition to NF2 and CHEK2 inactivation among thyroid cancers with chromosome 22q loss.