Metastatic Epithelioid Sarcoma Research Articles

19 Phase II Trial of Ubamatamab in MUC16-Expressing SMARCB1-Deficient Renal Medullary Carcinoma and Epithelioid Sarcoma

Abstract Background Mucin 16 (MUC16) is a large integral membrane glycoprotein that is highly expressed in malignancies such as ovarian cancer but only at low abundance in epithelial cells of normal tissues. Proteolytic cleavage of cell surface MUC16 results in the shedding of its extracellular portion, known as cancer antigen 125 (CA-125), into the bloodstream and a short, membrane-associated C-terminal MUC16 domain that remains on the cell surface. Renal medullary carcinoma (RMC) and epithelioid sarcoma (ES) are aggressive SMARCB1-deficient malignancies found to have elevated serum CA-125 levels in 70-80% of cases. Our preclinical studies suggest that upregulation of MUC16 upon SMARCB1 loss is a viable and attractive tumor target for SMARCB1-deficient malignancies such as ES and RMC. Ubamatamab is a human IgG4-based anti-MUC16 x anti-CD3 bispecific antibody that specifically targets the cell surface bound C-terminal MUC16 domain and can thus induce T cell–redirected killing of tumor cells even in the presence of high concentrations of CA-125. It would thus be a rationale therapy to use in SMARCB1-deficient malignancies expressing MUC16, including those such as RMC known to downregulate MHC Class I as a resistance mechanism to conventional immunotherapy. This is because CD3-targeting bispecific antibodies such as ubamatamab replace conventional signal 1 by engaging T cells regardless of MHC class I expression. As proof of concept, a 20-year-old patient with metastatic SMARCB1-negative ES expressing high levels of serum CA-125 achieved a durable (12+ months) partial response to ubamatamab after progressing on multiple prior therapies, including EZH2 inhibition with tazemetostat as well as anti-PD1/CTLA4 immune checkpoint inhibition with nivolumab plus ipilimumab. The patient reported Grade 2 CRS, pleural effusion, and pericardial effusion, all of which resolved without intervention1. This serves as proof-of-concept for the ability of CD3-targeted bispecifics to overcome resistance to immune checkpoint inhibition. Given this strong preclinical and clinical evidence, we have developed a phase II clinical trial of ubamatamab alone or in combination with the anti-PD1 immune-checkpoint inhibitor cemiplimab in patients with MUC16-expressing RMC and ES who have progressed on at least one line of prior therapy. Up to 20 patients will be enrolled from each disease cohort (ES and RMC) for a total of up to 40 patients. Patients enrolled in Stage I of the trial will receive ubamatamab monotherapy. Patients with disease progression on ubamatamab monotherapy during Stage I can proceed to stage II, which will evaluate the combination of ubamatamab with cemiplimab combination. The co-primary endpoints will be objective response rate (ORR) at any time during the trial and disease control rate (DCR) through 18 weeks. Secondary endpoints will include overall survival, progression-free survival, duration of response, and safety. All endpoints will be analyzed and reported separately for each disease cohort (RMC and ES), and for each Stage (ubamatamab monotherapy and combination ubamatamab with cemiplimab). The trial will utilize the time-to-event Bayesian Optimal Phase II (TOP) design, which maximizes statistical power with well-controlled type I errors. For patients with ES, the joint null hypotheses are that the objective response rate (ORR) is 15% and the disease control rate (DCR) is 26%. The regimen will be promising if either ORR is greater than 15% or DCR is greater than 26% with 69.6% power to declare this an interesting regimen if ORR is 30% and the DCR is 43%. For patients with RMC, the joint null hypotheses are that the objective response rate (ORR) is 15% and the disease control rate (DCR) is 15%. The regimen will be promising if either ORR is greater than 15% or DCR is greater than 15% with 71.4% power to declare this an interesting regimen if ORR is 30% and the DCR is 30%. Pre- and post-treatment correlative analyses will be performed in blood and tumor biopsy tissues to identify changes in specific immune cell subsets and elucidate the dynamic evolution of tumor and immune cell compartments as well as their spatial relationships following ubamatamab alone or in combination with cemiplimab. References 1 Revon-Riviere G, Chami R, Mills D, et al. Mucin 16 (cancer antigen 125) Expression in Epithelioid Sarcoma leads to Single-Patient Study with Bispecific T-Cell Engager Ubamatamab (Mucin16xCD3): A Bench-To-Bedside Experience. Connective Tissue Oncology Society, Nov 16–19, 2022, Vancouver, Canada.

Identification and characterization of the rat in-vivo and in-vitro metabolites of tazemetostat using LC-QTOF-MS

In drug discovery, metabolite profiling unveils biotransformation pathways and potential toxicant formation, guiding selection of candidates with optimal pharmacokinetics and safety profiles. Tazemetostat (TAZ) is employed in treating locally advanced or metastatic epithelioid sarcoma. Identification of drug metabolites are of significant importance in improving safety, efficacy and reduced toxicity of drugs. The current study aimed to investigate the comprehensive metabolic fate of TAZ using different in vivo (rat) and in vitro (RLM, HLM, HS9) models. For in vivo studies, drug was orally administered to Sprague–Dawley rats with subsequent analysis of plasma, feces and urine samples. A total of 21 new metabolites were detected across various matrices and were separated on Phenomenex kinetex C18 (2.5 μm; 150 × 4.6 mm) column using acetonitrile and 0.1% formic acid in water as mobile phase. LC-QTOF-MS/MS and NMR techniques were employed to identify and characterize the metabolites from extracted samples. The major metabolic routes found in biotransformation of TAZ were hydroxylation, N-dealkylation, N-oxidation, hydrogenation, hydrolysis and N-acetylation. In silico toxicity revealed potential immunotoxicity for TAZ and few of its metabolites. This research article is the first time to discuss the complete metabolite profiling including identification and characterization of TAZ metabolites as well as its biotransformation mechanism.

Efficacy and safety of SHR-2554 in advanced epithelioid sarcoma: A phase 2 trial.

11549 Background: Epithelioid sarcoma (ES) is a rare and aggressive subtype of soft-tissue sarcoma. The loss of SMARCB1 (INI1) expression which leads to oncogenic dependence on the transcriptional repressor EZH2 has been observed in over 90% of ES. Patients (pts) with metastatic ES have a poor prognosis. We investigated the efficacy and safety of SHR-2554, an oral selective EZH2 inhibitor, in pts with refractory ES. Methods: To be eligible for inclusion, pts had to fulfill the following criteria: 8 years or older; histologically confirmed advanced or metastatic ES with loss of INI1 or upregulated mRNA level of EZH2; progressive disease after at least one line of doxorubicin-containing chemotherapy; the presence of measurable disease according to RECIST 1.1; an ECOG performance status of 0-1. Pts received SHR2554 (350 mg, bid, po) until disease progression or unacceptable toxicity. The primary endpoint was progression-free rate at 12 weeks. A Simon two-stage design was applied. If there were 3 pts remaining progression-free at 12 weeks within the first 9 pts, the cohort would expand to 17 pts and the outcome would be positive if more than 7 pts remained progression-free at 12 weeks. Results: Between Jul 2021 and Dec 2023, a total of 17 pts were enrolled and received at least 1 dose of SHR-2554. The median age was 32 years (range 8-57) and 41.2% were males. 9 (52.9%) pts had received immunotherapy targeting PD-1/L1 and 6 (35.3%) pts had received anti-angiogenesis therapy before enrollment. The median line of previous treatment was 2 (range 1-4). Loss of INI1 was confirmed in 14 (82.4%) pts. Tumor response was evaluated in 14 pts at data cutoff. 9 (64.3%) of 14 pts remained progression-free at 12 weeks. The primary endpoint was met. Based on investigator assessment, 3 (21.4%) of 14 pts achieved partial response and 8 (57.1%) pts had stable disease as best response. Adverse events (AEs) were generally mild. The most common treatment-related hematological AEs were anaemia, platelet count decreased and hyperuricaemia. Conclusions: SHR-2554 showed promising efficacy and an acceptable safety profile in pts with refractory ES, warranting further investigation. Clinical trial information: ChiCTR2100046099.

HH2853, an EZH1/2 inhibitor, in patients with epithelioid sarcoma: Preliminary results from the phase 1 part of a first-in-human phase I/II study.

11562 Background: Epithelioid sarcoma (ES) is a rare and aggressive subtype of soft-tissue sarcoma. Over 90% of tumors have lost INI1 expression, leading to oncogenic dependence on the transcriptional repressor EZH2. Tazemetostat (an EZH2 inhibitor) has been approved by FDA for clinical use in ES. HH2853 is a novel selective EZH1/2 dual inhibitor, which has demonstrated superior anti-tumor efficacy to tazemetostat in INI1-loss preclinical models. Methods: This is a first-in-human, open-label, multi-center, Phase (Ph) I/II study in patients (pts) with relapsed/refractory non-Hodgkin lymphomas or advanced solid tumors. Ph I is composed of two parts: dose escalation and dose extension part. Local pathologically documented, advanced recurrent or metastatic ES pts who received prior systemic anti-tumor therapies or have no standard therapy are eligible. HH2853 was administered orally twice daily (BID) on a continuous 28-day treatment cycle. Safety and clinical activity of HH2853 were assessed in pts with ES from the Ph I part. Results: Between Dec 2, 2021 and Nov 7, 2022, 32 pts with pre-treated ES were enrolled to three dose levels (400, 600, and 800 mg BID) from 4 sites in China. Median prior lines of therapy was two. 12 (37.5%) pts received ≥3 lines of prior therapies. 30 (93.8%) pts had documented loss of INI1 expression by local immunohistochemical analysis. There were 18 (56.3%) pts with proximal subtype. As of Jan 4, 2023, at a median treatment duration of 124 days, the most common treatment-related adverse events (TRAE) were diarrhea (59.4%), blood bilirubin increased (43.8%), white blood cell count (WBC) decreased (34.4%), rash (31.3%), anemia (25.0%), hypokalemia (21.9%), and platelet count (PLT) decreased (21.9%). TRAEs of ≥Grade 3 included diarrhea, WBC decreased, anemia, hypokalemia, and neutrophil count decreased (6.2%, each), and blood bilirubin increased, PLT decreased, blood creatine phosphokinase increased, and hyperglycemia (3.1%, each). TRAEs leading to dose interruption or reduction were reported in 21.9% and 12.5% pts, respectively. No TRAE led to dose discontinuation or death. Tumor responses were observed from 400 to 800 mg BID. Overall response rate (ORR) was 15.6% (5/32) per investigator assessment according to RECIST 1.1. Three pts had unconfirmed response waiting to be confirmed at the next scheduled assessment, expecting to bring the total ORR to 25% [95% CI 11.5 – 43.4]. Median time to response was 1.9 months. One patient with complete response (CR) has responded for 222 days from the initial response. Disease control rate (DCR) (DCR = CR + partial response + stable disease at 6 weeks) was 78.1% [95% CI 60-90.7]. Conclusions: HH2853 showed an acceptable safety profile and promising anti-tumor activity in heavily pretreated ES pts with a wide therapeutic window, providing evidence for further investigation. Clinical trial information: NCT04390737 .

(368) Stuttering Priapism: A Rare Manifestation of Underlying Malignancy

Abstract Introduction First described by Peacock in 1938, malignant priapism (MP) is defined as persistent erection in the absence of sexual stimulation or other triggering factors. The proposed mechanism is due to neoplastic invasion of cavernous sinuses and venous system resulting in poor outflow and painful penile engorgement. Though rare, MP due to penile tumors has been described in cases of hematologic malignancies, primary penile neoplasms, local invasion from urologic primary tumors including prostate and bladder cancer, and penile metastasis from other primary sources. Objective Here we describe a case of metastatic epithelioid sarcoma that presented with recurrent priapism. Methods An otherwise healthy 43 year old male presented with two weeks of intermittent priapism. Initially thought to be traumatic in nature, the patient was managed conservatively with penile irrigation and phenylephrine. Though the patient achieved some improvement in his pain, full detumescence was never achieved. Approximately one month later the patient elected for placement of an inflatable penile prosthesis (IPP) due to persistent incomplete detumescence. At the time of surgery, extensive corporal induration was noted bilaterally. Upon entry into the corpora, copious purulent material was expressed from the tissues and the decision was made to abort the case. Prior to closure, several representative biopsies were collected. Results Blood gas performed at initial presentation was consistent with low flow priapism. Doppler studies showed intact arterial blood flow to the penis bilaterally and pelvic MRI was negative for penile injury though asymmetric enhancement of the corpora was noted incidentally. Surgical pathology revealed an unclassified malignancy and increased proliferation concerning for metastasis. A PET scan was performed which was consistent with widely metastatic disease with mets to the liver, lung, bone, muscles, adrenal glands, brain, and penis. Percutaneous biopsy of an abdominal mass confirmed the diagnosis of epithelioid sarcoma. Despite palliative chemotherapy and radiation the patient succumbed to his cancer just two months after diagnosis. Conclusions Epithelioid sarcoma is a rare soft tissue neoplasm primarily affecting young adult males and representing less than 1% of soft tissue sarcomas. Even rarer is the incidence of metastatic penile tumors, with fewer than 500 cases reported in the literature since 1850. A literature review by Lin YH et al based on reports from 2006 to 2011 suggested that the true incidence of penile metastasis may be higher given that 12% of penile metastasis may be asymptomatic and discovered only at autopsy. To our knowledge, this is the first case of widely metastatic epithelioid sarcoma presenting with priapism secondary to penile metastasis. Disclosure No

Functional genomic analysis of epithelioid sarcoma reveals distinct proximal and distal subtype biology.

BackgroundMetastatic epithelioid sarcoma (EPS) remains a largely unmet clinical need in children, adolescents and young adults despite the advent of EZH2 inhibitor tazemetostat.MethodsIn order to realise consistently effective drug therapies, a functional genomics approach was used to identify key signalling pathway vulnerabilities in a spectrum of EPS patient samples. EPS biopsies/surgical resections and cell lines were studied by next‐generation DNA exome and RNA deep sequencing, then EPS cell cultures were tested against a panel of chemical probes to discover signalling pathway targets with the most significant contributions to EPS tumour cell maintenance.ResultsOther biologically inspired functional interrogations of EPS cultures using gene knockdown or chemical probes demonstrated only limited to modest efficacy in vitro. However, our molecular studies uncovered distinguishing features (including retained dysfunctional SMARCB1 expression and elevated GLI3, FYN and CXCL12 expression) of distal, paediatric/young adult‐associated EPS versus proximal, adult‐associated EPS.ConclusionsOverall results highlight the complexity of the disease and a limited chemical space for therapeutic advancement. However, subtle differences between the two EPS subtypes highlight the biological disparities between younger and older EPS patients and emphasise the need to approach the two subtypes as molecularly and clinically distinct diseases.

Lerociclib diminishes stemness in pediatric sarcoma cell lines.

e22010 Background: The outcomes for children with osteosarcoma and synovial sarcoma remain poor and are even worse for metastatic or relapsed disease. Those who do survive frequently suffer from long-term toxicities from current standard-of-care therapies. It is evident novel therapeutics are warranted to improve the outcomes for patients with these difficult tumors. Stem cell-like cancer cells (SCLCCs) are a subpopulation of tumor cells thought to be responsible for treatment resistance, development of metastases and tumor recurrence, making the targeting of this cell population critical. We sought to evaluate the effect of lerociclib, a CDK4/6 inhibitor, on pediatric sarcoma cell stemness. Methods: We investigated two established human osteosarcoma cells lines (U2-OS and MG-63), two metastatic synovial sarcoma patient-derived xenografts (PDXs) (COA-30 and COA-79) and a metastatic epithelioid sarcoma PDX (COA-171). Cells were treated with the CDK4/6 inhibitor, lerociclib, at concentrations below the known LD50. Synovial sarcoma stemness markers Octamer-binding transcription factor 4 (Oct4), homeobox protein Nanog, SOX 2 and nestin were evaluated by qPCR. CD117, a marker of stemness in osteosarcoma cells, was examined by flow cytometry. Finally, long-term passaged U2-OS and MG-63 cells were placed in low attachment serum-free conditions, and tumorsphere formation was evaluated using extreme limiting dilution assay (ELDA) in all cell lines. Results: Lerociclib treatment significantly decreased abundance of Oct4 (by 54%), Nanog (by 29%), SOX 2 (by 60%) and nestin (by 63%) mRNA in COA-30 synovial sarcoma cells. Cell surface expression of CD117 decreased from 17% to 11% in MG-63 cells when treated with lerociclib 2μM. Treatment of all cell types with lerociclib led to significantly decreased tumorsphere formation (Table). Conclusions: Treatment with lerociclib led to a decrease in mRNA abundance in known synovial sarcoma stem cell markers, a decrease in CD117 cell surface expression in osteosarcoma cells and decreased the ability of cells to form tumorspheres. These findings indicate lerociclib leads to decreased sarcoma cell stemness, which plays a key role in tumor progression and recurrence and should be further investigated for potential translation to the clinical setting.[Table: see text]

EZH2 Inhibitors Suppress Colorectal Cancer by Regulating Macrophage Polarization in the Tumor Microenvironment

EZH2 inhibitors (EZH2i), a class of small-molecule inhibitors that target EZH2 to exert anti-tumor functions, have just been approved by the US Food and Drug Administration (FDA) in treatment of adults and adolescents with locally advanced or metastatic epithelioid sarcoma. The application of EZH2i in several solid tumors is still in different stages of clinical trials and needs to be further validated. As a key epigenetic regulator, besides its role in controlling the proliferation of tumor cells, EZH2 has been implicated in the regulation of various immune cells including macrophages. But there are still controversial research results at present. Colorectal cancer (CRC) is a common malignant tumor that highly expresses EZH2, which has the third highest incidence and is the second leading cause of cancer-related death worldwide. Studies have shown that the numbers of M2-type tumor-associated macrophages (TAMs) are highly associated with the progression and metastasis of CRC. In the current study, we aim to investigate how EZH2 modulates the polarization of macrophages in the tumor microenvironment (TME) of CRC, and compare the role of two different EZH2 inhibitors, EPZ6438 and GSK126. We applied a 3D culture method to demonstrate that EZH2i did indeed suppress the proliferation of CRC cells in vitro. In vivo, we found that the percentage of CD206+ macrophages of the TME was decreased under the treatment of EPZ6438, but it increased upon GSK126 treatment. Besides, in the co-culture system of macrophages and CRC cells, EPZ6438 led to significant elevation of M1 markers and reduction of M2 markers. Furthermore, mechanistic studies validated by ChIP-qPCR demonstrated that EZH2i inhibit EZH2-mediated H3K27me3 levels on the promoters of STAT3, an essential transcription factor for M1 macrophage polarization. Therefore, our data suggested that EZH2i not only suppress CRC cell proliferation directly, but also regulate macrophage by skewing M2 into effector M1 macrophage to exert a tumor suppressive effect. Moreover, our study provided new insight for better understanding of the role of two kinds of EZH2i: EPZ6438 and GSK126, which may pave the way in treating CRC by targeting cancer cells and immune cells via this epigenetic approach in the future.

Abstract 696: Phototheranostics of epithelioid sarcoma by targeting CD44 or EGFR

Abstract Introduction: Epithelioid sarcoma (ES) is a rare yet high-grade and highly aggressive soft tissue neoplasm first identified by Enzinger in 1970.1 ES has high reported recurrence and metastasis rates (around 70% and 50%, respectively).2 Unresectable locally advanced and metastatic ES are usually chemoresistant and generally fatal.3 Here, we extended our previous near-infrared photoimmunotherapy (NIR-PIT) study,4 to develop antibody photosensitizer conjugates based on two monoclonal antibodies (mAbs) binding to CD44 or EGFR, both overexpressed on ES tumor cell surface. We conducted cellular studies and established animal models to evaluate the specificity and efficacy of the two mAb conjugates in binding, detecting and eliminating ES. Method: CD44, EGFR mAb or its IgG isotype control was conjugated with a NIR phthalocyanine dye, IR700, to form CD44-IR700, EGFR-IR700 and IgG-IR700, respectively. A bilateral ES tumor model was established by inoculating 1×106 VAESBJ cells in 0.05 ml of Hank's balanced salt solution on either flank of athymic Balb/c (nu/nu) female mouse. Subsequently, 100 μg of CD44-IR700 or EGFR-IR700 or IgG-IR700 was injected intravenously (i.v.), and NIR fluorescence images of IR700 in mice were obtained over a 24-h period (n = 4 per group). For PIT, tumor-bearing mice (n = 4 or 5 per group) received two i.v. injections of 100 μg of CD44-IR700 or EGFR-IR700 at a one-week interval, and tumors were exposed to NIR light exposure at 200 J/cm2 at 24h p.i. Tumor diameters were measured over 3 weeks. IgG-IR700 and PBS-injected mice were used as controls. Results and Discussion: We confirmed CD44 and EGFR overexpression in VAESBJ cells by flow cytometry. Both CD44-IR700 and EGFR-IR700 demonstrated target-specific binding to VAESBJ and cell death when activated by NIR light. Compared to EGFR-IR700, CD44-IR700 exhibited a higher potency in cellular PIT and had a much lower IC50 value. CD44-IR700 and EGFR-IR700 both exhibited preferential accumulation in VAESBJ tumors and showed approximately two to threefold higher retention compared to IgG-IR700. CD44-IR700 or EGFR-IR700 injection combined with NIR light exposure resulted in significant tumor growth delay in VAESBJ tumors compared to the IgG-IR700 or PBS group. Reduction of CD44 and EGFR levels were observed in the corresponding CD44-IR700 or EGFR-IR700-treated tumors as evidenced by flow cytometry and western blotting studies. Our data collectively demonstrate the specificity and efficacy of CD44 or EGFR-based PIT as novel therapeutic approaches that can be integrated into an intraoperative setting for achieving clear tumor margins in localized ES or applied as a standalone therapy for inoperable locally advanced and recurrent ES.

Tazemetostat– A Drug review

Epithelioid sarcoma affects three in 10 million people, usually teenagers and young adults. Tumours grow under the skin of the extremities or they can affect the trunk, head, or neck. It grows slowly, but can infiltrate surrounding tissues, later on, it frequently metastasis to lymph nodes. For advanced case, doxorubicin-based chemotherapy regimen is recommended. In January 2020, FDA approved the first-in-class, small molecule enhancer of zeste homolog 2 (EZH2) inhibitor, tazemetostat (Tazverik) to treat adults and paediatric patients aged 16 years and older with locally advanced or metastatic epithelioid sarcoma not suitable for complete resection. The recommended dosage is 800 mg twice daily until disease progression or unacceptable toxicity. The first-in-human study of tazemetostat was a phase 1 open-label multi-centered dose-escalation study. Tazemetostat is having an oral bioavailability of approximately 33%. Apparent volume of distribution at steady-state (Vss/F) is 1230 L (46%) with 88% bound to human plasma proteins. Metabolism takes place via CYP3A. 15% and 79% of radioactivity is excreted through urine and feces respectively. ≥20% of the adverse reactions and above was fatigue, pain, constipation, nausea, anorexia and vomiting. This article summarizes the history, chemistry, physical properties, mechanism of action, indications, and drug–drug interactions of tazemetostat and we also discuss briefly the results of various clinical trials.

Real-world outcomes of patients with locally advanced or metastatic epithelioid sarcoma.

BackgroundLimited data are available on the real‐world effectiveness and safety of systemic therapies for advanced (surgically unresectable and/or metastatic) epithelioid sarcoma (ES).MethodsA retrospective medical records review was conducted in patients with advanced ES who were initiating first‐line or ≥2 lines of systemic therapy (2000‐2017) at 5 US cancer centers. The real‐world overall response rate (rwORR), the duration of response (rwDOR), the disease control rate (rwDCR) (defined as stable disease for ≥32 weeks or any duration of response), and progression‐free survival (rwPFS) were assessed by radiology reports. Overall survival (OS), rwDOR, and rwPFS were estimated from the time therapy was initiated using the Kaplan‐Meier method. Serious adverse events were assessed.ResultsOf 74 patients (median age at diagnosis, 33 years; range, 10.6‐76.3 years), 72% were male, and 85% had metastatic disease. The median number of lines of therapy was 2 (range, 1‐7 lines of therapy), and 46 patients (62%) received ≥2 lines of systemic therapy. First‐line regimens were usually anthracycline‐based (54%) or gemcitabine‐based (24%). For patients receiving first‐line systemic therapy, the rwORR was 15%, the rwDCR was 20%, the median rwDOR was 3.3 months (95% CI, 2.1‐5.2 months), the median rwPFS was 2.5 months (95% CI, 1.7, 6.9 months), and the median OS was 15.2 months (95% CI, 11.4‐21.7 months). For those who received ≥2 lines of systemic therapy, the rwORR was 9%, the rwDCR was 20%, the median rwDOR was 4.5 months (95% CI, 0.7‐5.6 months), and the median rwPFS was 6.0 months (95% CI, 3.2‐7.4 months). Over one‐half of patients (51.4%) experienced an adverse event, most frequently febrile neutropenia (14%), pain (10%), anemia, dyspnea, fever, thrombocytopenia, or transaminitis (5% each).ConclusionsSystemic therapies demonstrate limited efficacy in patients with advanced ES and have associated toxicities.

Tazemetostat for Advanced Epithelioid Sarcoma: Current Status and Future Perspectives

Epithelioid sarcoma (ES) is an aggressive ultra-rare soft-tissue sarcoma marked by SMARCB1/INI1 deficiency. SMARCB1/INI1 deficiency leads to elevated expression of EZH2, a component of polycomb repressive complex 2, which mediates gene silencing by catalyzing H3K27me3. Tazemetostat is an oral, SAM-competitive inhibitor of EZH2, whose blockade prevents the methylation of histone H3K27, thus decreasing the growth of EZH2 mutated or over-expressing cancer cells. Tazemetostat has been approved for the treatment of patients aged 16 years and older with metastatic or advanced ES not eligible for complete resection, based on the positive results of a single-arm Phase II basket study. Tazemetostat though represents a new treatment option for ES patients, although clinical/molecular predictors of response are still to be identified. The combination of tazemetostat with other drugs like doxorubicin and immunotherapeutic agents is currently under investigation in ES patients.

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.

Tazemetostat: First Approval.

Tazemetostat (Tazverik™), a first-in-class, small molecule enhancer of zeste homolog 2 (EZH2) inhibitor, received accelerated approval in January 2020 in the USA for the treatment of adults and adolescents aged ≥16years with locally advanced or metastatic epithelioid sarcoma not eligible for complete resection. Developed by Epizyme, in collaboration with Eisai, it is the first therapy to be approved specifically for the treatment of epithelioid sarcoma in the USA. The recommended dosage regimen is 800mg twice daily, administered orally with or without food, until disease progression or unacceptable toxicity. Tazemetostat is also undergoing clinical development in various countries worldwide for use in several other tumour types, including diffuse large B-cell lymphoma and mesothelioma, with the US FDA accepting a New Drug Application and granting priority review for its use in the treatment of follicular lymphoma. This article summarizes the milestones in the development of tazemetostat leading to this first approval for the treatment of adults and adolescents aged ≥ 16years with locally advanced or metastatic epithelioid sarcoma not eligible for complete resection.

1687P - Real-world outcomes of patients with locally advanced or metastatic epithelioid sarcoma

BackgroundLimited data are available on effectiveness and safety of systemic therapies for treatment of advanced (unresectable and/or metastatic) epithelioid sarcoma (ES). This natural history study collected real-world (rw) data on outcomes of ES patients (pts) receiving at least first-line (1L) or 2 or more lines (2L+) of systemic therapies. MethodsRetrospective chart review was conducted in pts with advanced ES who initiated systemic therapy between 2000-2017 at 5US cancer centers. Due to unavailability of RECIST assessment, rw overall response rate (rwORR) was assessed by review of radiology reports. rw disease control rate (rwDCR) was defined as percent of pts with response of any duration or stable disease ≥32 wks. Median rw duration of response (rwDOR), rw progression-free survival (rwPFS) and overall survival (OS) were estimated from start of therapy by Kaplan-Meier method. The index date for time-to-event endpoints was the start of first-line treatment. Adverse events (AEs) resulting in treatment modification, discontinuation, hospitalization, permanent sequelae or death, were abstracted. ResultsOf 74 eligible pts, 53 (71.6%) were male, and 63 (85.1%) had metastatic ES. INI1/BAF47 was not expressed in 90.2% of 41 tumors tested. Mean age at advanced ES diagnosis was 36.4 years. Anthracycline-based (54.1%) and gemcitabine-based (24.3%) regimens were most common in 1L. Median (range) number of lines of therapy received was 2 (1-7). 1L rwORR was 14.9%, rwDCR was 20.3%, rwDOR was 14.5 wks, and median OS was 66.3 wks. The table shows 1L and 2L+ results. Over 50% of pts had an AE; most frequently febrile neutropenia (13.5%), pain (9.5%), anemia, dyspnea, fever, thrombocytopenia and transaminitis (5.4% each). ConclusionsCurrently available systemic therapies are not specific for advanced ES, have a limited response durability and low tolerability. This is the largest US-based rw study that provides benchmarking treatment efficacy and safety data for development of standard of care therapies for ES.Table1687P Real-world outcomes by line of therapyTable1L N=742L+ N=46rwORR (95% CI), %14.9 (7.7-25.0)9.4 (4.4-17.1)Median rwDOR (95% CI), wks14.5 (9.1-22.6)19.6 (3.1-24.3)rwDCR (95% CI), %20.3 (11.8-31.2)19.8 (12.4-29.2)Median rwPFS (95% CI), wks11.0 (7.3-29.9)26.0 (13.9-32.0)Median OS (95% CI), wks66.3 (49.6-94.1)43.3 (33.6-78.3) Legal entity responsible for the studyEpizyme, Inc. FundingEpizyme, Inc. DisclosureM.M. Gounder: Advisory / Consultancy, Travel / Accommodation / Expenses: Epizyme; Honoraria (self), Advisory / Consultancy: Karyopharm; Honoraria (self), Advisory / Consultancy: Daiichi; Honoraria (self): TRACON; Honoraria (self): Amgen. P. Merriam: Advisory / Consultancy: Lilly. S.R. Patel: Advisory / Consultancy, Research grant / Funding (self): Janssen; Advisory / Consultancy: PharmaMar; Advisory / Consultancy: MJ Hennessey/Onc Live; Advisory / Consultancy: Novartis; Advisory / Consultancy: Immune D; Research grant / Funding (self): Eisai; Research grant / Funding (self): Blueprint Medicines; Research grant / Funding (self): Bavarian Nordic. R. Chugh: Advisory / Consultancy: Epizyme, Janssen ,EMD Serono; Research grant / Funding (institution): AADi (Institution), Novartis (Institution), Lilly (Institution), Medivation (Institution), Advenchen (Institution), Epizyme (Institution), Plexiconn (Institution), Pfizer (Institution); Research grant / Funding (self): Portoia Pharmaceuticals. M. Thorton: Research grant / Funding (self): Epizyme; Advisory / Consultancy: Biologics Consulting Group; Shareholder / Stockholder / Stock options: Ziopharm, Novavax, Zogenix. B.A. Van Tine: Advisory / Consultancy, Research grant / Funding (institution): Epizyme. A.H. Abdelhamid: Research grant / Funding (institution): Dubai Harvard Foundation. P. Joshi: Full / Part-time employment: Epizyme. J. Whalen: Full / Part-time employment: Epizyme. J. Yang: Shareholder / Stockholder / Stock options, Full / Part-time employment: Epizyme. A. Rajarethinam: Shareholder / Stockholder / Stock options, Full / Part-time employment: Epizyme. M.S. Duh: Research grant / Funding (self): Epizyme, Novartis, GlaxoSmithKline, Janssen, Pfizer, Bayer, Taiho Pharmaceutical; Speaker Bureau / Expert testimony: AbbVie. P.J. Bobbili: Research grant / Funding (self): Epizyme, Novartis, AstraZeneca, GlaxoSmithKline. C.L. Cavanaugh: Research grant / Funding (institution): Epizyme, GlaxoSmithKline, NovoNordisk, Merck, Eisai, AstraZeneca. L. Huynh: Research grant / Funding (institution): Epizyme, Novartis, Pfizer, Taiho Pharmaceutical; Travel / Accommodation / Expenses: Novartis. T. Totev: Research grant / Funding (institution): Epizyme, Novartis, Takeda (formerly Shire). G. Demetri: Shareholder / Stockholder / Stock options: Blueprint Medicines, Merrimack G1 Therapeutics; Caris Life Sciences; Chapions Oncology; Besson Phramceuticals; Advisory / Consultancy: Novartis, Pfizer, EMD Serono, Jannsen, Ignyta, Loxo, Mirati Therapeutics, Epizyme, PharmaMar, Daiichi Sankyo, WIRB-copernicus group, Ziopharm Oncology, Polaris, Bluprint Medicines, Merrimack, G1 Therapeutics, Caris Life Sciences, Champions Oncology, Besso; Research grant / Funding (institution): Bayer, Novartis, Pfizer, Jannsen, Ignyta, Loxo, AbbVie, Epizyme, AdaptImmune.; Licensing / Royalties: Novartis. All other authors have declared no conflicts of interest.

Safety and efficacy of tazemetostat, a first-in-class EZH2 inhibitor, in patients (pts) with epithelioid sarcoma (ES) (NCT02601950).

11003 Background: ES is a rare soft tissue sarcoma that metastasizes in approximately 30% to 50% of cases. More than 90% of ES tumors lack expression of INI1, an important component of epigenetic regulation. Loss of INI1 function allows another epigenetic modifier, EZH2, to become an oncogenic driver in tumor cells. Tazemetostat, a first-in-class, selective, oral inhibitor of EZH2, has demonstrated tumor regression and favorable safety in phase 1/2 trials. Methods: Data from a phase 2 open-label, multicenter trial of pts with locally advanced or metastatic ES are reported. Efficacy was assessed with primary and secondary endpoints including objective response rate (ORR) by RECIST 1.1, disease control rate (DCR; objective confirmed response of any duration or stable disease [SD] lasting ≥32 weeks), duration of response (DOR), progression-free survival (PFS), overall survival (OS); safety and tolerability were also evaluated. Results: As of September 17, 2018, 62 INI1-negative ES pts were enrolled and treated with tazemetostat 800 mg BID. The median number of prior lines of therapy was 1 (range: 0-9). There were 9/62 (15%) confirmed partial responses (PRs) with an ORR of 15% and DCR of 26%. The DOR ranged from 7.1+ weeks to 103.0+ weeks (median: not reached) with a median OS of 82.4 weeks (95% CI: 47.4, not estimable) for all 62 pts. Tazemetostat was generally well tolerated. Treatment-emergent adverse events (TEAEs) were generally mild to moderate with the most commonly reported adverse events (AEs; ≥10% incidence) regardless of attribution being fatigue (24/62; 39%), nausea (22/62; 35%), and cancer pain (20/62; 32%). Any treatment-related TEAEs of grade ≥3 were reported in 10/62 (16%) pts. TEAEs grade ≥3 reported in ≥2 pts included anemia (6%) and decreased weight (3%). There were no drug-related deaths and a low discontinuation rate (1.7%). Conclusions: In the largest prospective clinical trial of ES to date, tazemetostat achieved disease control in 26% of pts with advanced ES who entered this study. Durable clinical response of the drug was documented. Tazemetostat demonstrated favorable safety with few pts with treatment-related AEs grade ≥3. Clinical trial information: NCT02601950.

Different subtypes of epithelioid sarcoma and their clinical implication: long-term multi-institutional experience with a rare sarcoma.

Epithelioid sarcoma (ES) is a very rare soft-tissue sarcoma with a high tendency of recurrence and metastasis. We analyzed clinical features of ES and aimed to identify the potential role of radio- and chemotherapy in ES. Fifty-five patients diagnosed with ES between 1997 and 2014 were enrolled from seven tertiary hospitals in Korean Cancer Research Group. The clinical variables were retrospectively reviewed and analyzed. Forty-six (84%) patients underwent surgical resection of ES, and among them, 27 experienced recurrence. In these patients, resection margin status and adjuvant radiotherapy were independent prognostic factors for longer recurrence-free survival (RFS), while adjuvant chemotherapy did not influence RFS. Twenty-two (40%) patients received palliative chemotherapy for metastatic or recurrent ES, and in these patients, palliative chemotherapy was the only independent prognostic factor for longer overall survival. Intriguingly, the clinical benefit of radio- and chemotherapy was observable only in proximal ES, but not in extremity ES, indicating that subtypes of ES might respond to radio- or chemotherapy differently. Proximal ES seems to benefits more from active anticancer treatment than conventional extremity ES. The aggressive characteristics of proximal ES could be overcome with an optimal multimodal treatment.

Vinorelbine-based chemotherapy in metastatic epithelioid sarcoma.

e22549Background: Epithelioid sarcoma (ES) is a rare soft tissue sarcoma subtype, with poor and short-term responses to conventional, doxorubicin-based chemotherapy (Jones et al, Am J Clin Oncol 20...

Metastatic epithelioid sarcoma revealed with 18F-FDG PET/CT imaging

Metastatic epithelioid sarcoma revealed with 18F-FDG PET/CT imaging

Stabilization of multiple metastatic epithelioid sarcoma under treatment with sunitinib malate

Stabilization of multiple metastatic epithelioid sarcoma under treatment with sunitinib malate