Synergistic Antitumor Activity of Talazoparib and Temozolomide in Malignant Rhabdoid Tumors.

Malignant rhabdoid tumors (MRTs) are among the most aggressive and treatment-resistant malignancies affecting infants, originating in the kidney, brain, liver, and soft tissues. The 5-year event-free survival rate for these cancers is a mere 20%. In nearly all cases of MRT, the SMARCB1 gene (occasionally SMARCA4)-a pivotal component of the SWI/SNF chromatin remodeling complex-is homozygously deleted, although the precise etiology of these tumors remains unknown. While young patients with localized MRT generally show improved outcomes, especially those who are older and have early-stage disease, the overall prognosis remains poor despite optimal standard treatments. This highlights the urgent need for more effective treatment strategies. We investigated the antitumor activity of a PARP1 inhibitor (talazoparib, TLZ) combined with a DNA alkylating agent (temozolomide, TMZ) in MRT xenograft models. PARP1 is a widely targeted molecule in cancer treatment and, beyond its role in DNA repair, it participates in transcriptional regulation by recruiting chromatin remodeling complexes to modulate DNA accessibility for RNA polymerases. To widen the therapeutic window of the drug combination, we employed PEGylated TLZ (PEG~TLZ), which has been reported to reduce systemic toxicity through slow drug release. Remarkably, our findings indicate that five out of six MRT xenografts exhibited an objective response to PEG~TLZ+TMZ therapy. Significantly, the loss of SMARCB1 was found to confer a protective effect, correlating with higher expression levels of DNA damage and repair proteins in SMARCB1-deficient MRT cells. Additionally, we identified MGMT as a potential biomarker indicative of in vivo MRT response to PEG~TLZ+TMZ therapy. Moreover, our analysis revealed alterations in signaling pathways associated with the observed antitumor efficacy. This study presents a novel and efficacious therapeutic approach for MRT, along with a promising candidate biomarker for predicting tumor response.

Malignant Extrarenal Rhabdoid tumor derived from the greater omentum: A case report and literature review.

BACKGROUND: Malignant extrarenal rhabdoid tumor (MERT) is a rare and highly metastatic tumor, which is more than 75% of patients dying within 6 months of initial diagnosis, and it often leads to misdiagnosis and delayed treatment. CASE: This paper reports a 16-year-old girl who presented with the chief complaint of acute abdominal pain. She underwent laparoscopic exploration and excisional biopsy, then pathological examination and immunohistochemistry revealed "extrarenal malignant rhabdomyoma." One month after operation, she died of intra-abdominal hemorrhage and multiple organ dysfunction. CONCLUSION: MERT were often misdiagnosed and had a poor prognosis. The surgery and chemotherapy are usually beneficial to prolong the survival time of patients with MERT.

Congenital Disseminated Malignant Rhabdoid Tumor Mimicking a Vascular Lesion.

A congenital disseminated malignant rhabdoid tumor (MRT) is an exceedingly rare and aggressive pediatric cancer marked by the presence of malignant rhabdoid cells in various organs, including the brain, kidneys, and soft tissues, at birth. It is often detected prenatally or shortly post-birth. The malignancy's aggressiveness results in a bleak prognosis, offering limited treatment options and low survival rates. Early diagnosis and comprehensive medical intervention are crucial, but managing this condition is complicated by its rarity. We herein presented a case of a 37 and 1/7 week gestation male infant with a rapidly growing arm soft tissue mass within two weeks, diagnosed as an MRT. Post-delivery examinations revealed multiple lesions in the lungs, kidney, liver, and adrenal glands. Notably, chemotherapy yielded a significant improvement in the arm lesion, contrasting with other lesions showing a limited response. This observation suggests potential tumor heterogeneity, emphasizing the necessity of diverse therapeutic regimens. Our case underscores the complexities of congenital disseminated MRT, prompting a reevaluation of treatment strategies for enhanced efficacy in managing this challenging pediatric cancer.

False-Positive Asymmetrical Tongue Muscle 18F-FDG Uptake in Hypoglossal Nerve Paralysis Following Lymph Node Dissection in a Pediatric Patient with Malignant Rhabdoid Tumor of the Neck.

BACKGROUND: Although positron emission tomography combined with computed tomography (PET-CT) plays an important role in detecting various types of childhood malignancy, it has low positive predictive value, owing to the nonspecific uptake of 18F-fluorodeoxyglucose (FDG) by normal tissue in various benign conditions. CASE SUMMARY: A 5-year-old male patient with a malignant rhabdoid tumor originating in the left neck underwent primary tumor resection concurrently with ipsilateral lymph node dissection after receiving neoadjuvant chemotherapy consisting of cyclophosphamide, carboplatin, etoposide, vincristine, and doxorubicin. He later received the same adjuvant chemotherapy as well as proton therapy for the primary tumor. Sixteen months after completing the initial therapy, follow-up PET-CT revealed a novel area of glucose hypermetabolism in the right side of the tongue, which was suspected of being a recurrence. However, a physical examination and magnetic resonance imaging (MRI) demonstrated no evidence of tumor recurrence. The patient had a significant leftward deviation of the tongue, suggesting left hypoglossal nerve paralysis. Denervation of the ipsilateral intrinsic tongue muscles secondary to the treatment had caused atrophy in the ipsilateral muscles and compensatory hypertrophy in the contralateral muscles, which increased FDG uptake. Physicians should carefully confirm any diagnosis of a locally recurrent tumor because PET-CT often produces ambiguous findings.

Rhabdoid tumor predisposition syndrome: A historical review of treatments and outcomes for associated pediatric malignancies.

Rhabdoid tumor predisposition syndrome (RTPS) is a rare disorder associated with malignant rhabdoid tumor of the kidney (RTK), atypical teratoid rhabdoid tumor (ATRT), and/or other extracranial, extrarenal rhabdoid tumors (EERT), and these pediatric malignancies are difficult to treat. Presently, most of the information regarding clinical manifestations, treatment, and outcomes of rhabdoid tumors comes from large data registries and case series. Our current understanding of treatments for patients with rhabdoid tumors may inform how we approach patients with RTPS. In this manuscript, we review the genetic and clinical features of RTPS and, using known registry data and clinical reports, review associated tumor types ATRT, RTK, and EERT, closing with potential new approaches to treatment. We propose collaborative international efforts to study the use of SMARC (SWI/SNF-related, matrix-associated, actin-dependent regulator of chromatin)-targeting agents, high-dose consolidative therapy, and age-based irradiation of disease sites in RTPS.

Extracranial malignant rhabdoid tumors in children: high mortality even with the help of an aggressive clinical approach.

This paper aims to explore the epidemiology, clinical characteristics, and prognosis of extracranial malignant rhabdoid tumors (eMRTs) in children. A systematic review and meta-analysis of studies published in PUBMED, MEDLINE, Web of Science, Embase, Cochrane, and China National Knowledge Infrastructure (CNKI) was conducted. The search was limited to studies published between Jan 1, 1990 to Dec 31, 2022, with the last search done on Jan 31, 2023. We identified 496 papers through the literature search, and 12 retrospective cohort studies with 398 patients were included. The pooled age at diagnosis for malignant rhabdoid tumor of the kidney (MRTK) was 10.009 months (95%CI (7.542-12.476)), while extracranial malignant rhabdoid tumor (EERT) was 25.917 months (95%CI (17.304-34.530)). Among the 398 patients with eMRTs, chemotherapy treatment rate (86.8% (95%CI (74.4-96.0%))) was more frequently than radiotherapy treatment (45.4% (95%CI (38.1-52.6%))). The rate of metastasis in all patients was 41.4% (95%CI (33.9-48.9%)), in which the lung metastasis was occupied 70.4% (95%CI (58.0-81.6%)). SMARCB1/INI1 mutation was up to 93.2% (95%CI (81.3-99.8%)). The rate of total surgical resection was 50.4% (95%CI (35.2-65.6%)), while pooled proportion of death in all patients was 68.7% (95%CI (56.9-79.5%)).     Conclusion: EMRTs are highly malignant tumors associated with high mortality rates. The loss of SMARCB1/INI1 gene and the protein expression is observed in the vast majority of eMRTs patients. Patients that suffered MRTK are younger than patients with extrarenal EERT and are more prone to lung metastasis, but there is no significant difference in overall survival, possibly due to the higher rate of R0 resection of primary tumors in MRTK.     Trial registration: The study was registered on PROSPERO with registration number CRD42023400985. What is Known: • Malignant rhabdoid tumor (MRT) is a rare and highly malignant tumor that may originate from embryonic stem cells. The incidence of MRT is exceptionally low, estimated at 0.00006%. • Malignant rhabdoid tumor of the kidney (MRTK) and extrarenal extra-cranial malignant rhabdoid tumor (EERT) tend to manifest between 11 to 18 months of age, with a 5-year survival rate of approximately 17%-36%. What is New: • There is no comprehensive meta-analysis or large-scale case series that reported to systematically introduce the eMRTs clinic outcome and prog-nosis based on largely pooled data. • This study performed a meta-analysis through an extensive literature search and clinical data analysis in order to mainly explore the clinical characteris-tics and prognosis of eMRTs, improving the understanding of eMRTs in children..

Decoding the rhabdoid riddle in liver: A rare case of primary hepatic malignant rhabdoid tumor with a comprehensive literature review.

Malignant rhabdoid tumor of the liver is a rare, highly aggressive primary hepatic malignancy occurring primarily in infants. Establishing a definitive diagnosis is challenging due to its rarity, non-specific clinicoradiologic findings, and overlapping morphologic features. Herein, we present the cytomorphologic and immunocytochemical characteristics of a rare case of primary hepatic Malignant rhabdoid tumor (MRT) in an infant. A 5-month-old female child presented with progressively increasing firm mass in the upper abdomen, progressive pallor, sudden onset respiratory distress, and difficulty feeding. On examination, the child had massive, firm nodular hepatomegaly. Ultrasonography of the abdomen revealed a heterogeneously hypoechoic lesion in the left lobe of the liver. Serum alpha-fetoprotein levels were within normal limits. An ultrasound-guided fine-needle aspiration cytology (FNAC) from the liver mass showed predominantly dispersed large, markedly pleomorphic tumor cells with round to oval eccentrically placed nuclei, prominent nucleoli, and moderate cytoplasm. On immunocytochemistry, tumor cells showed positivity for vimentin, cytokeratin, and EMA and demonstrated a loss of INI1, confirming the diagnosis of MRT. The index report highlights the distinctive clinicopathological features of a hepatic malignant rhabdoid tumor along with the key differential diagnoses, which may pose a diagnostic conundrum. A high index of clinical suspicion and a thorough understanding of its cytomorphological and immunochemical characteristics are crucial for an accurate diagnosis.

Doxycycline hydrochloride inhibits the progress of malignant rhabdoid tumor of kidney by targeting MMP17 and MMP1 through PI3K-Akt signaling pathway.

OBJECTIVE: To identify therapeutic targets for malignant rhabdoid tumors of kidney (MRTK) and to investigate the effects and underlying mechanism of doxycycline hydrochloride on these tumors. METHODS: Gene expression and clinical data of MRTK were retrieved from the TARGET database. Differentially expressed genes (DEGs) and prognostic-related genes (PRGs) were selected through a combination of statistical analyses. The functional roles of MMP17 and MMP1 were elucidated through RNA overexpression and intervention experiments. Furthermore, in vitro and in vivo studies provided evidence for the inhibitory effect of doxycycline hydrochloride on MRTK. Additionally, transcriptome sequencing was employed to investigate the underlying molecular mechanisms. RESULTS: 3507 DEGs and 690 PRGs in MRTK were identified. Among these, we focused on 41 highly expressed genes associated with poor prognosis and revealed their involvement in extracellular matrix regulatory pathways. Notably, MMP17 and MMP1 stood out as particularly influential genes. When these genes were knocked out, a significant inhibition of proliferation, invasion and migration was observed in G401 cells. Furthermore, our study explored the impact of the matrix metalloproteinase inhibitor, doxycycline hydrochloride, on the malignant progression of G401 both in vitro and in vivo. Combined with sequencing data, the results indicated that doxycycline hydrochloride effectively inhibited MRTK progression, due to its ability to suppress the expression of MMP17 and MMP1 through the PI3K-Akt signaling pathway. CONCLUSION: Doxycycline hydrochloride inhibits the expression of MMP17 and MMP1 through the PI3K-Akt signaling pathway, thereby inhibiting the malignant progression of MRTK in vivo and in vitro.

Malignant rhabdoid tumor of kidney in an adult patient with positive family history of rhabdoid tumor: A case report and review of literature.

INTRODUCTION AND IMPORTANCE: Malignant rhabdoid tumor of kidney (MRTK) is almost exclusive to children. Only 10 cases of adult MRTK have been reported. Here, we present a case of MRTK in an adult patient and discuss its clinical findings, diagnostic challenges, and treatment outcome. We also perform literature review on this issue. CASE PRESENTATION: Our patient was a 29-year-old woman presented with fever and hematuria. She also mentioned atypical teratoid/rhabdoid tumor of cerebellum in her deceased child. Initial diagnostic work up led to left partial nephrectomy with the pathology report of high grade undifferentiated tumor. Early tumor recurrence necessitated left radical nephrectomy with extensive excision of adjacent tissues. Pathology for second specimen considering disease course and family history was MRTK. Even though chemotherapy was administered, she died few months later due to multiple metastases. CLINICAL DISCUSSION: Although diagnosis is challenging in all 11 reported cases -including our case- of adult MRTK, immunohistochemistry (i.e., negative reaction for INI-1) in conjunction with clinical and radiological findings are the main tool to reach diagnosis. Treatment options are much more diverse, ranging from surgery to immunotherapy, tyrosine kinase inhibitors, chemotherapy, and combination of these modalities. Prognosis remains dismal with the mean survival period of 7 months. CONCLUSION: Although extremely rare, MRTK might happen in adults. We report the first case of adult MRTK with positive family history of rhabdoid tumor of CNS, underscoring the importance of family history in reaching the diagnosis and highlighting the role of genetics in this rare disease.

Malignant rhabdoid tumor of the omentum in an adult male: a case report and literature review.

Malignant rhabdoid tumors (MRTs) are rare tumors with high mortality rates and poor prognoses. MRTs occur mainly in the central nervous system, kidneys, and soft tissues, but rarely in the omentum. MRTs occur more commonly in infants and children and less frequently in adults. Here, we report the first observed case of MRT in an adult omentum. A 35-year-old man with abdominal distension and pain was admitted to the emergency department. Previously, several hospitals considered patients with cirrhosis who had not received active treatment. Computed tomography and magnetic resonance imaging revealed diffuse omental thickening and massive ascites. The surgery was performed at our hospital, and the pathological diagnosis was MRT with a SMARCB1(INI-1) deletion. Postoperatively, his symptoms improved, and he underwent five cycles of chemotherapy. However, 6 months after surgery, the tumor developed liver metastases, and the patient subsequently died. Primary MRT of the greater omentum is rare, and its pathological diagnosis usually requires extensive clinicopathological evaluation of various differential diagnoses and an appropriate work-up to exclude other malignancies associated with SMARCB1 deletion. At the same time, the lack of specific signs of omental MRT and its rapid progression should alert clinicians.

Rhabdoid tumors in patients conceived following ART: is there an association?

STUDY QUESTION: In children affected by rhabdoid tumors (RT), are there clinical, therapeutic, and/or (epi-)genetic differences between those conceived following ART compared to those conceived without ART? SUMMARY ANSWER: We detected a significantly elevated female predominance, and a lower median age at diagnosis, of children with RT conceived following ART (RT_ART) as compared to other children with RT. WHAT IS KNOWN ALREADY: Anecdotal evidence suggests an association of ART with RT. STUDY DESIGN, SIZE, DURATION: This was a multi-institutional retrospective survey. Children with RT conceived by ART were identified in our EU-RHAB database (n = 11/311 children diagnosed between January 2010 and January 2018) and outside the EU-RHAB database (n = 3) from nine different countries. A population-representative German EU-RHAB control cohort of children with RTs conceived without ART (n = 211) (EU-RHAB control cohort) during the same time period was used as a control cohort for clinical, therapeutic, and survival analyses. The median follow-up time was 11.5 months (range 0-120 months) for children with RT_ART and 18.5 months (range 0-153 months) for the EU-RHAB control cohort. PARTICIPANTS/MATERIALS, SETTING, METHODS: We analyzed 14 children with RT_ART diagnosed from January 2010 to January 2018. We examined tumors and matching blood samples for SMARCB1 mutations and copy number alterations using FISH, multiplex ligation-dependent probe amplification, and DNA sequencing. DNA methylation profiling of tumor and/or blood samples was performed using DNA methylation arrays and compared to respective control cohorts of similar age (n = 53 tumors of children with RT conceived without ART, and n = 38 blood samples of children with no tumor born small for gestational age). MAIN RESULTS AND THE ROLE OF CHANCE: The median age at diagnosis of 14 individuals with RT_ART was 9 months (range 0-66 months), significantly lower than the median age of patients with RT (n = 211) in the EU-RHAB control cohort (16 months (range 0-253), P = 0.03). A significant female predominance was observed in the RT_ART cohort (M:F ratio: 2:12 versus 116:95 in EU-RHAB control cohort, P = 0.004). Eight of 14 RT_ART patients were diagnosed with atypical teratoid rhabdoid tumor, three with extracranial, extrarenal malignant rhabdoid tumor, one with rhabdoid tumor of the kidney and two with synchronous tumors. The location of primary tumors did not differ significantly in the EU-RHAB control cohort (P = 0.27). Six of 14 RT_ART patients presented with metastases at diagnosis. Metastatic stage was not significantly different from that within the EU-RHAB control cohort (6/14 vs 88/211, P = 1). The incidence of pathogenic germline variants was five of the 12 tested RT_ART patients and, thus, not significantly different from the EU-RHAB control cohort (5/12 versus 36/183 tested, P = 0.35). The 5-year overall survival (OS) and event free survival (EFS) rates of RT_ART patients were 42.9 ± 13.2% and 21.4 ± 11%, respectively, and thus comparable to the EU-RHAB control cohort (OS 41.1 ± 3.5% and EFS 32.1 ± 3.3). We did not find other clinical, therapeutic, outcome factors distinguishing patients with RT_ART from children with RTs conceived without ART (EU-RHAB control cohort). DNA methylation analyses of 10 tumors (atypical teratoid RT = 6, extracranial, extrarenal malignant RT = 4) and six blood samples from RT_ART patients showed neither evidence of a general DNA methylation difference nor underlying imprinting defects, respectively, when compared to a control group (n = 53 RT samples of patients without ART, P = 0.51, n = 38 blood samples of patients born small for gestational age, P = 0.1205). LIMITATIONS, REASONS FOR CAUTION: RTs are very rare malignancies and our results are based on a small number of children with RT_ART. WIDER IMPLICATIONS OF THE FINDINGS: This cohort of patients with RT_ART demonstrated a marked female predominance, and a rather low median age at diagnosis even for RTs. Other clinical, treatment, outcome, and molecular factors did not differ from those conceived without ART (EU-RHAB control cohort) or reported in other series, and there was no evidence for imprinting defects. Long-term survival is achievable even in cases with pathogenic germline variants, metastatic disease at diagnosis, or relapse. The female preponderance among RT_ART patients is not yet understood and needs to be evaluated, ideally in larger international series. STUDY FUNDING/COMPETING INTEREST(S): M.C.F. is supported by the 'Deutsche Kinderkrebsstiftung' DKS 2020.10, by the 'Deutsche Forschungsgemeinschaft' DFG FR 1516/4-1 and by the Deutsche Krebshilfe 70113981. R.S. received grant support by Deutsche Krebshilfe 70114040 and for infrastructure by the KinderKrebsInitiative Buchholz/Holm-Seppensen. P.D.J. is supported by the Else-Kroener-Fresenius Stiftung and receives a Max-Eder scholarship from the Deutsche Krebshilfe. M.H. is supported by DFG (HA 3060/8-1) and IZKF Münster (Ha3/017/20). BB is supported by the 'Deutsche Kinderkrebsstiftung' DKS 2020.05. We declare no competing interests. TRIAL REGISTRATION NUMBER: N/A.

Targeting EZH2 in SMARCB1-deficient sarcomas: Advances and opportunities to potentiate the efficacy of EZH2 inhibitors.

Soft tissue sarcomas (STSs) are rare mesechymal malignancies characterized by distintive molecular, histological and clinical features. Many STSs are considered as predominatly epigenetic diseases due to underlying chromatin deregulation. Discovery of deregulated functional antagonism between the chromatin remodeling BRG1/BRM-associated (BAFs) and the histone modifying Polycomb repressor complexes (PRCs) has provided novel actionable targets. In epithelioid sarcoma (ES), extracranial, extrarenal malignant rhabdoid tumors (eMRTs) and synovial sarcoma (SS), the total or partial loss of the BAF core subunit SMARCB1, driven by different alterations, is associated with PRC2 deregulation and dependency on its enzymatic subunit, EZH2. In these SMARCB1-deficient STSs, aberrant EZH2 expression and/or activity emerged as a druggable vulnerability. Although preclinical investigation supported EZH2 targeting as a promising therapeutic option, clinical studies demonstrated a variable response to EZH2 inhibitors. Actually, whereas the clinical benefit recorded in ES patients prompted the FDA approval of the EZH2 inhibitor tazemetostat, the modest and sporadic responses observed in eMRT and SS patients highlighted the need to deepen mechanistic as well as pharmacological investigations to improve drug effectiveness. We summarize the current knowledge of different mechanisms driving SMARCB1 deficiency and EZH2 deregulation in ES, eMRT and SS along with preclinical and clinical studies of EZH2-targeting agents. Possible implication of the PRC2- and enzymatic-independent functions of EZH2 and of its homolog, EZH1, in the response to anti-EZH2 agents will be discussed together with combinatorial strategies under investigation to improve the efficacy of EZH2 targeting in these tumors.

Malignant rhabdoid tumors of the vulva versus epithelioid sarcomas: a clinicopathologic, immunohistochemical, and molecular genetics study.

It has been suggested that most, if not all, extrarenal rhabdoid tumors of the vulva represent "proximal-type" epithelioid sarcomas. To better understand rhabdoid tumors of the vulva, we studied the clinicopathologic, immunohistochemical (IHC), and molecular features of 8 of these tumors and 13 extragenital epithelioid sarcomas. IHC analysis for cytokeratin AE1/AE3, EMA, S100, CD34, ERG, smooth muscle actin, desmin, and SMARCB1 (INI1) was performed. Ultrastructural study was done in one vulvar rhabdoid tumor. Next-generation sequencing of the SMARCB1 gene was performed in all cases. The 8 vulvar tumors occurred in adult women (mean age, 49 years). They were poorly differentiated neoplasms with a rhabdoid morphology. The ultrastructural study showed large amounts of intermediate filaments (10 nm). All cases had loss of expression of INI1 and were negative for CD34 and ERG. One case showed 2 SMARCB1 mutations: c.592C>T in exon 5 and c.782delG in exon 6. Follow-up revealed that 4 patients died of disease, 1 was alive with disease, and 3 were alive without evidence of disease. Epithelioid sarcomas occurred in young adults (mean age, 41 years), mostly men. Seven tumors arose in the distal extremities and the other 6 had a proximal location. They showed the characteristic "granulomatous" arrangement of the neoplastic cells. The recurrent tumors were more proximal and often showed a rhabdoid morphology. All cases had loss of expression of INI1. CD34 and ERG were expressed by 8 (62%) and 5 (38%) tumors, respectively. No SMARCB1 mutations were encountered. Follow-up revealed that 5 patients died of disease, 1 was alive with disease, and 7 were alive without evidence of disease. Based on their different morphology and biological behavior, we conclude that rhabdoid tumors of the vulva and epithelioid sarcomas are different diseases with distinct clinicopathologic features. Undifferentiated vulvar tumors with rhabdoid morphology should be classified as malignant rhabdoid tumors, rather than "proximal-type" epithelioid sarcomas.

A Rare Case of Undifferentiated Rhabdoid Carcinoma of the Colon.

Rhabdoid carcinoma of the colon is a rare type of malignancy that belongs to the family of malignant rhabdoid tumors (MRTs). This is infrequently encountered in clinical settings therefore data regarding treatment is lacking. Herein we discuss an elderly female patient who presented with severe abdominal pain in the setting of a gastrointestinal perforation. Imaging showed a large mass in the transverse colon, which was found to be an undifferentiated carcinoma of the colon with rhabdoid features. We highlight this case to discuss the clinical course of the patient, thereby adding to the limited literature that is available, as well as review the few studies that have, thus far, documented this rare presentation.

Multidisciplinary management of pediatric malignant rhabdoid tumor based on 5 years of experience at a tertiary care center.

OBJECTIVE: Malignant rhabdoid tumor (MRT) is a highly aggressive tumor that occurs mostly in young children with extremely poor prognosis. Standardized and effective treatment strategies for MRT have yet to be established because of its rarity. Here, we report our single-institutional experience involving MRT treatment. METHODS: Patients with newly diagnosed MRT between March 2016 and October 2021 were included. The clinical characteristic, treatment-related toxicities, clinical outcomes, and prognostic factor were retrospectively analyzed. RESULTS: A total of 18 patients with MRT were enrolled during the 5 years. The median age was 42.8 months (range 10 to 82 years). Among the 18 patients, 9 patients died after a median of follow-up 26 months (range 3 to 42 months). The 1-year event-free survival (EFS) and 3-year overall survival (OS) rates of the entire cohort were 63% (95% CI 46% to 74%) and 67% (95% CI 49% to 82%), respectively. Univariate analysis of patients who underwent gross or total resection followed by adjuvant chemotherapy and radiotherapy demonstrated an improvement in 1-year EFS. However, only gross resection and total resection predicted a better 3-year OS. CONCLUSIONS: Surgical excision is still the mainstream treatment for MRT. Postoperative adjuvant treatments including chemotherapy and radiotherapy contribute to improved disease control rate. Our single-institute experience may provide insights into the multimodal treatment of MRT.

RUNX1-Survivin Axis Is a Novel Therapeutic Target for Malignant Rhabdoid Tumors.

Malignant rhabdoid tumor (MRT) is a highly aggressive pediatric malignancy with no effective therapy. Therefore, it is necessary to identify a target for the development of novel molecule-targeting therapeutic agents. In this study, we report the importance of the runt-related transcription factor 1 (RUNX1) and RUNX1-Baculoviral IAP (inhibitor of apoptosis) Repeat-Containing 5 (BIRC5/survivin) axis in the proliferation of MRT cells, as it can be used as an ideal target for anti-tumor strategies. The mechanism of this reaction can be explained by the interaction of RUNX1 with the RUNX1-binding DNA sequence located in the survivin promoter and its positive regulation. Specific knockdown of RUNX1 led to decreased expression of survivin, which subsequently suppressed the proliferation of MRT cells in vitro and in vivo. We also found that our novel RUNX inhibitor, Chb-M, which switches off RUNX1 using alkylating agent-conjugated pyrrole-imidazole polyamides designed to specifically bind to consensus RUNX-binding sequences (5'-TGTGGT-3'), inhibited survivin expression in vivo. Taken together, we identified a novel interaction between RUNX1 and survivin in MRT. Therefore the negative regulation of RUNX1 activity may be a novel strategy for MRT treatment.

Clinical and prognostic analysis of 42 children with malignant rhabdoid tumor of the kidney: a 7-year retrospective multi-center study.

OBJECTIVE: To discuss the clinical and prognostic indicators of pediatric malignant rhabdoid tumor of the kidney (MRTK), and to increase the understanding of the occurrence and development of MRTK. METHODS: From July 2014 to September 2021, all cases were confirmed by postoperative pathological examination. Among the 42 patients, there were 25 males and 17 females, with a median age of 10 (1-84) months. Abdominal mass or hematuria were the main clinical manifestations. Preoperative chemotherapy was performed in 9 cases (VC). The tumor stages were stage I-IV. Preoperative metastasis was found in 9 cases; the most common site was the lung. Postoperative patients received conventional chemotherapy, including VDACE regimen and UH-1 regimen. Among the 42 children in this group, survival at follow-up in this study was 26.2%(11/42). RESULTS: Preoperative anemia was found by univariate analysis, hypertension and hypercalcemia had shorter survival time. In addition, tumor-related factors had a significant impact on survival, with incomplete tumor resection, lymph node metastasis, stage III-IV had a lower survival rate. The impact of postoperative factors on survival included postoperative complications had a lower survival rate. The children were younger than 12 months, preoperative metastasis, no chemotherapy was performed after surgery was an independent risk factor for the prognosis of MRTK. CONCLUSION: The main clinical manifestations about MRTK were abdominal mass and hematuria. Preoperative chemotherapy did not significantly improve the prognosis. Postoperative chemotherapy can significantly improve the survival rate. Diagnosis depends on clinical manifestations, imaging, histopathology, immunohistochemistry and other comprehensive judgment. Age less than 12 months, preoperative metastasis, and no postoperative chemotherapy were independent risk factors for prognosis.

Molecular Heterogeneity in Pediatric Malignant Rhabdoid Tumors in Patients With Multi-Organ Involvement.

Rhabdoid tumors (RTs) of the brain (atypical teratoid/rhabdoid tumor; AT/RT) and extracranial sites (most often the kidney; RTK) are malignant tumors predominantly occurring in children, frequently those with SMARCB1 germline alterations. Here we present data from seven RTs from three pediatric patients who all had multi-organ involvement. The tumors were analyzed using a multimodal molecular approach, which included exome sequencing of tumor and germline comparator and RNA sequencing and DNA array-based methylation profiling of tumors. SMARCB1 germline alterations were identified in all patients and in all tumors. We observed a second hit in SMARCB1 via chr22 loss of heterozygosity. By methylation profiling, all tumors were classified as rhabdoid tumors with a corresponding subclassification within the MYC, TYR, or SHH AT/RT subgroups. Using RNA-seq gene expression clustering, we recapitulated the classification of known AT/RT subgroups. Synchronous brain and kidney tumors from the same patient showed different patterns of either copy number variants, single-nucleotide variants, and/or genome-wide DNA methylation, suggestive of non-clonal origin. Furthermore, we demonstrated that a lung and abdominal metastasis from two patients shared overlapping molecular features with the patient's primary kidney tumor, indicating the likely origin of the metastasis. In addition to the SMARCB1 events, we identified other whole-chromosome events and single-nucleotide variants in tumors, but none were found to be prognostic, diagnostic, or offer therapeutic potential for rhabdoid tumors. While our findings are of biological interest, there may also be clinical value in comprehensive molecular profiling in patients with multiple rhabdoid tumors, particularly given the potential prognostic and therapeutic implications for different rhabdoid tumor subgroups demonstrated in recent clinical trials and other large cohort studies.

Establishment and characterization of NCC-MRT1-C1: a novel cell line of malignant rhabdoid tumor.

Malignant rhabdoid tumor (MRT) is a sarcoma histologically characterized by rhabdoid cells and genetically characterized by loss of function of the chromatin remodeling complex SWI/SNF induced by SMARCB1 gene deficiency. MRT mainly occurs in children, may arise in various locations, but is predominantly in the central nervous system (CNS) and kidney. Although MRT exhibits poor prognosis, standard treatment has not yet been established due to its extreme rarity. Patient-derived cancer cell lines are critical tools for basic and pre-clinical research in the development of chemotherapy. However, none of the MRT cell lines was derived from adult patients, and only one cell line was derived from the MRT of a soft tissue, despite the clinical behavior of MRT varying according to patient age and anatomic site. Herein, we reported the first cell line of MRT isolated from the soft tissue of an adult patient and named it NCC-MRT1-C1. NCC-MRT1-C1 cells showed a biallelic loss of the SMARCB1 gene. NCC-MRT1-C1 cells demonstrated rapid proliferation, spheroid formation, invasion capability in vitro, and tumorigenesis in nude mice. Screening of antitumor agents in NCC-MRT1-C1 cells resulted in the identification of six effective drugs. In conclusion, we report the first MRT cell line from the soft tissue of an adult patient. We believe that NCC-MRT1-C1 is a useful tool for developing novel chemotherapies for MRT.