Advanced Epithelioid Sarcoma Research Articles

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.

Pharmacology and pharmacokinetics of tazemetostat.

Tazemetostat, a novel oral selective inhibitor of enhancer of zeste homolog 2 (EZH2), was approved by the Food and Drug Administration (FDA) in 2020 for use in patients with advanced epithelioid sarcoma or relapsed/refractory (R/R) EZH2-mutated follicular lymphoma. These indications were approved by the FDA trough accelerated approval based on objective response rate and duration of response that resulted from phase 2 clinical trials. Tazemetostat competes with S-adenosylmethionine (SAM) cofactor to inhibit EZH2, reducing the levels of trimethylated lysine 27 of histone 3 (H3K27me3), considered as pharmacodynamic marker. Tazemetostat is orally bioavailable, characterized by rapid absorption and dose-proportional exposure, which is not influenced by coadministration with food or gastric acid reducing agents. It highly distributes in tissues, but with limited access to central nervous system. Tazemetostat is metabolized by CYP3A in the liver to 3 major inactive metabolites (M1, M3, and M5), has a short half-life and is mainly excreted in feces. Drug-drug interactions were shown with moderate CYP3A inhibitors as fluconazole, leading the FDA to recommend a 50% dose reduction, while studies investigating coadministration of tazemetostat with strong inhibitors/inducers are ongoing. No dosage modifications are recommended based on renal or hepatic dysfunctions. Overall, tazemetostat is the first-in-class EZH2 inhibitor approved by the FDA for cancer treatment. Current clinical studies are evaluating combination therapies in patients with several malignancies.

1941P Preliminary efficacy and safety of SHR-2554 in advanced epithelioid sarcoma: A phase II trial

1941P Preliminary efficacy and safety of SHR-2554 in advanced epithelioid sarcoma: A phase II trial

EZH2 inhibitor Tazemetostat synergizes with JQ-1 in esophageal cancer by inhibiting c-Myc signaling pathway.

EZH2, a highly conserved histone methyltransferase, plays an essential role in tumorigenesis and development. The inhibitor of EZH2 tazemetostat has been approved to treat metastatic or locally advanced epithelioid sarcoma and recurrent or refractory follicular lymphoma. However, the effect of tazemetostat alone or in combination with other drugs in esophageal cancer has not been reported. In this study, we found that EZH2 was highly expressed in esophageal cancer at both mRNA and protein levels through transcriptomic and proteomic analyses. Furthermore, the results of CCK8, colony formation, cell cycle and cell apoptosis assays revealed that tazemetostat exerted an antitumour effect on esophageal cancer cells. Mechanistically, RNA-sequencing analysis of the tazemetostat-treated cells and vehicle-treated ones suggested that tazemetostat mainly inhibited the c-Myc signaling pathway and its targets, which was validated by western blotting. JQ-1, an inhibitor of bromodomain 4, was proven to attenuate c-Myc signaling in tumors. Thus, a therapeutic strategy based on tazemetostat in combination with JQ-1 is promising. The results demonstrated that tazemetostat and JQ-1 had a synergistic effect in vitro and in vivo for esophageal cancer.

Tazemetostat synergistically combats multidrug resistance by the unique triple inhibition of ABCB1, ABCC1, and ABCG2 efflux transporters in vitro and ex vivo

ATP-binding cassette (ABC) drug efflux transporters and drug metabolizing enzymes play crucial roles in pharmacokinetic drug-drug interactions and multidrug tumor resistance (MDR). Tazemetostat (EPZ-6438, Tazverik) is a novel epigenetic drug that has been recently approved for the therapy of advanced epithelioid sarcoma and follicular lymphoma. Additionally, this medication is currently being clinically tested to treat several other cancers such as non-small cell lung cancer (NSCLC). This study aimed to investigate the inhibitory effects of tazemetostat on selected ABC transporters/cytochrome P450 3A4 (CYP3A4) enzyme to comprehensively explore its role in MDR. First, our accumulation and molecular docking studies showed that tazemetostat is a unique triple inhibitor of ABCB1, ABCC1, and ABCG2 transporters. In contrast, tazemetostat exhibited only low level of interaction with the CYP3A4 isozyme. Drug combination assays confirmed that tazemetostat is a multipotent MDR modulator able to synergize with various conventional chemotherapeutics in vitro. Subsequent caspase activity assays and microscopic staining of apoptotic nuclei proved that the effective induction of apoptosis is behind the observed synergies. Notably, a potent MDR-modulatory capacity of tazemetostat was recorded in primary ex vivo NSCLC explants generated from patients’ biopsies. On the contrary, its possible position of pharmacokinetic MDR’s victim was excluded in comparative proliferation assays. Finally, tested drug has not been identified as an inducer of resistant phenotype in NSCLC cell lines. In conclusion, we demonstrated that tazemetostat is a unique multispecific chemosensitizer, which has strong potential to overcome limitations seen in the era of traditional MDR modulators.

Abstract A022: Targeting of soft tissue sarcoma cancer stem cells improves doxorubicin-sensitivity in vitro

Abstract Soft tissue sarcomas (STS) are rare tumors encompassing over 70 distinct histopathological subtypes that share a common treatment strategy comprising surgical resection, radiation, and chemotherapy in certain situations. Disease progression and failure to respond to anthracycline based chemotherapy, a standard first-line agent, is associated with poor outcomes. Recurrence and chemo-resistance represent significant barriers to improving patient survival. We are interested in the contribution of STS cancer stem cells (STS-CSCs) to the phenomenon of chemo-resistance to doxorubicin. Specifically, we hypothesized the presence of a common genetic signature across unique STS subtypes involved in CSC-regulation that could be targeted to improve the efficacy of existing treatment regimens. To this end, STS-CSCs were profiled by flow cytometry using the Aldeflour assay. This is a well-established technique to measure the aldehyde dehydrogenase activity of cells which is high in the stem cell population. This fluorescently labels Aldefluor bright and dim cells as CSCs and non-CSCs, respectively. The abundance of the CSC population in several STS cell lines modeling dedifferentiated liposarcoma, leiomyosarcoma, and undifferentiated pleomorphic sarcoma were assessed by Aldeflour assay. In order to gain insight into the molecular pathways active in STS-CSCs, Aldeflour-bright and -dim populations were isolated by FACs and analyzed by RNA-sequencing. Gene-set enrichment analysis of genes upregulated in STS-CSCs identified a signature for the histone methyltransferase Enhancer of Zeste homolog 2 (EZH2), part of the polycomb repressive complex 2 (PRC2) responsible for H3K27 methylation. As an epigenetic modulator, increased EZH2 expression and activity potentiates decreased activity of genes involved in growth suppression and thereby has oncogenic activity. EZH2 can be inhibited with small molecules such as Tazemetostat, an approved treatment for metastatic and locally advanced epithelioid sarcoma. To test the effects of EZH2 inhibition on STS-CSCs, we first generated doxorubicin resistance STS cell lines by serial selection with increasing concentrations of doxorubicin. We identified a positive correlation between CSC abundance and doxorubicin IC50 in the resistant cell lines. Further, co-treatment of doxorubicin and tazemetostat was not only synergistic in the parent cell lines, but restored chemosensitivity in doxorubicin resistant lines. These data confirm the presence of shared genetic programs across distinct subtypes of STS that are unique to CSCs and amenable to therapeutic targeting. Citation Format: Edmond F. O'Donnell, Maria Muñoz, Lor Randall, Janai R. Carr-Ascher. Targeting of soft tissue sarcoma cancer stem cells improves doxorubicin-sensitivity in vitro [abstract]. In: Proceedings of the AACR Special Conference: Sarcomas; 2022 May 9-12; Montreal, QC, Canada. Philadelphia (PA): AACR; Clin Cancer Res 2022;28(18_Suppl):Abstract nr A022.

1258P HJM-353: A potent, selective and orally bioavailable EED inhibitor with robust anti-tumor activities

Polycomb Repressive Complex 2 (PRC2), a multimeric complex that catalyzes the methylation of histone H3 at lysine 27 with core subunits EZH2, EED and SUZ12, functions as an epigenetic modulator in regulating cell proliferation and development. Dysregulation of the PRC2 complex is implicated in hematological and solid malignancies and shown to correlate with poor prognosis in cancers. Recently EZH2 inhibitor Tazemetostat has been approved by FDA for the treatment of advanced epithelioid sarcoma and follicular lymphoma. However, acquired resistant mutations in EZH2 and complementary activation of EZH1 might impair the effectiveness of this class of PRC2 inhibitors. Targeting the allosteric subunit EED represents a new strategy to fully inhibit PRC2 activity and address the limitations of EZH2 inhibition. Herein, we report HJM-353 as an efficacious EED inhibitor for cancer therapy. In vitro activities of HJM-353 were assessed by CTG assay and Western blot in EZH2 mutant human cell lines.In vivo anti-tumor activities of HJM-353 were evaluated in DLBCL and gastric cancer xenograft models.Pharmacokinetic/pharmacodynamics correlation of HJM-353 was determined by LC-MS/MS, Western blot and Q-PCR. HJM-353 effectively reduced H3K27me3 level and inhibited cell proliferation with an IC50 of 33.8 nM in WSU-DLCL2 cells. It displayed favorable PK properties and induced complete tumor regression in KARPAS-422 derived DLBCL xenograft model. Plasma concentration of HJM-353 correlated with the inhibition of H3K27me3 and upregulation of PRC2 target genes in tumors, indicating a clear PK/PD relationship in the xenografts. In addition, HJM-353 caused tumor stasis as MAK683 did in a xKATO-III gastric xenograft model. In summary, HJM-353 is a potent, selective and orally bioavailable EED inhibitor with robust anti-tumor activities. We are developing HJM-353 for the treatment of hematological malignancies and solid tumors and expect to file an IND in the second half of 2022.

Establishment of an epithelioid sarcoma PDCs and PDX to evaluate drug sensitivity

Epithelioid sarcoma (ES) is a very rare mesenchymal malignancy. Its oncogenesis remains unknown, and few therapies are available for advanced patients. Improved therapies, such as combined therapies, are urgently needed for the treatment of advanced ES. To identify precision drugs for advanced ES patients, the sensitivity of the drugs must be screened and evaluated before they are used for treatment. In the present study, tumour tissue from an ES patient was subjected to NGS sequencing, cell culture and the construction of a PDX model. Using the early generations of tumour-derived cells, we performed a screen and found that the combined drugs ADM and trametinib exhibited coefficiency in tumour inhibition. This conclusion was further confirmed in experiments with later generations of cells and PDX models. Therefore, we suggest that early generations of tumour-derived cells be used to test the sensitivity of ES tumours to candidate drugs. Moreover, we speculate that trametinib may be combined with chemotherapy in ES patients to prolong the duration of the chemotherapeutic response.

Chemical biology and pharmacology of histone lysine methylation inhibitors

Histone lysine methylation is a post-translational modification that plays a key role in the epigenetic regulation of a broad spectrum of biological processes. Moreover, the dysregulation of histone lysine methyltransferases (KMTs) has been implicated in the pathogenesis of several diseases particularly cancer. Due to their pathobiological importance, KMTs have garnered immense attention over the last decade as attractive therapeutic targets. These endeavors have culminated in tens of chemical probes that have been used to interrogate many aspects of histone lysine methylation. Besides, over a dozen inhibitors have been advanced to clinical trials, including the EZH2 inhibitor tazemetostat approved for the treatment of follicular lymphoma and advanced epithelioid sarcoma. In this Review, we highlight the chemical biology and pharmacology of KMT inhibitors and targeted protein degraders focusing on the clinical development of EZH1/2, DOT1L, Menin-MLL, and WDR5-MLL inhibitors. We also briefly discuss the pharmacologic targeting of other KMTs.

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>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<0.05). All R (6/6) had <125,000 total neutrophils at C1D1 vs 42% (8/19) of NR; 50% (3/6) of R had >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]

Tazemetostat: EZH2 Inhibitor.

Epigenetic regulation is a novel approach to cancer treatment. Inhibition of enhancer of zeste homolog 2 (EZH2) is a method to provide targeted epigenetic regulation. Tazemetostat is a first-in-class targeted epigenetic regulator that specifically inhibits EZH2. This new FDA-approved oral treatment received accelerated approval for patients with hematologic and solid malignancies. Tazemetostat was first approved for patients 16 years and older with metastatic or locally advanced epithelioid sarcoma not eligible for complete resection based on the results of an international open-label phase II basket trial. Another open-label multicenter phase II trial led to the approval for patients with relapsed or refractory follicular lymphoma with EZH2 mutation who have received at least two prior systemic therapies or patients who have no satisfactory alternative treatment options. Tazemetostat as an oral EZH2 inhibitor provides a new effective and tolerable treatment option for these patients.

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.

Results of the phase 1b soft-tissue sarcoma (STS) portion of the global randomized, double-blind, placebo-controlled study of tazemetostat (TAZ) plus doxorubicin (DOX) as frontline therapy for advanced epithelioid sarcoma (ES).

11563 Background: ES is a rare, aggressive subtype of STS for which cytotoxic chemotherapy has limited effectiveness. TAZ, an FDA-approved EZH2 inhibitor, has shown single-agent clinical activity and a favorable safety profile in patients with metastatic or locally advanced ES. In preclinical studies, TAZ has shown synergistic antitumor activity with DOX, which is often used as frontline treatment for STS. Here, we present results of the phase 1b study (NCT04204941), designed to assess the recommended phase 3 dose (RP3D), safety, and efficacy of TAZ + DOX in patients with advanced STS. Methods: The open-label, phase 1b portion of this study enrolled adult patients with previously untreated advanced STS. A standard 3 + 3 design was used to assess TAZ 400 mg, 600 mg, and 800 mg orally twice daily in combination with DOX (75 mg/m2 intravenously on day 1 of each cycle, for up to 6 cycles) as frontline therapy. Dose-limiting toxicities (DLTs) were predefined in the protocol. The RP3D of TAZ was determined by Scientific Review Committee review of the safety and pharmacokinetic data from the phase 1b trial, with a target DLT rate of < 33%. Results: As of February 1, 2021, 16 patients are enrolled, including 2 with ES; 10 are still receiving TAZ + DOX and 6 have discontinued (5 due to disease progression, 1 due to patient withdrawal). The median age was 49.5 years (range, 29–82) and all had unresectable STS. Median (range) time on treatment was 13 (0.1–51.1+) weeks across all dose levels evaluated. Two DLTs, both of febrile neutropenia, were observed, one in the TAZ 600 mg + DOX cohort (n = 1/6, 17%), and one in the TAZ 800 mg + DOX cohort (n = 1/3, 33%). When used in combination with DOX, the RP3D of TAZ was 800 mg. Grade 3 or 4 treatment-related treatment-emergent adverse events (TR-TEAEs) occurred in 13/16 (81.3%) patients. The most common (≥ 20%) TR-TEAEs were neutropenia (n = 11, 69%), anemia (n = 10, 63%), fatigue (n = 10, 63%), stomatitis (n = 9, 56%), nausea (n = 8, 50%), febrile neutropenia (n = 7, 44%), constipation (n = 6, 38%), vomiting (n = 6, 38%), and decreased appetite (n = 5, 31%). TR-TEAEs were defined as attributable to either study agent. Conclusions: The combination of TAZ + DOX was generally well tolerated in this dose finding study in patients with advanced STS. The RP3D to be tested in the phase 3 randomized, double blind, placebo controlled study is TAZ 800 mg twice daily + DOX. The safety profile of this combination is consistent with the respective safety information for TAZ and for DOX. The TR-TEAEs include known toxicities of DOX or TAZ. Further comparison with DOX + placebo in the phase 3 trial will aid in assessing efficacy and safety of the combination of TAZ + DOX. The global phase 3 confirmatory trial will enroll patients with ES who have unresectable disease and have had no prior systemic therapy. Clinical trial information: NCT04204941.

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.

RETRACTED ARTICLE: Inhibition of EZH2 enhances the therapeutic effect of 5-FU via PUMA upregulation in colorectal cancer

Although the survival rate of patients with cancer have increased due to the use of current chemotherapeutic agents, adverse effects of cancer therapy remain a concern. The reversal of drug resistance, reduction in harmful side effects and accelerated increase in efficiency have often been addressed in the development of combination therapeutics. Tazemetostat (EPZ-6438), a histone methyltransferase EZH2 selective inhibitor, was approved by the FDA for the treatment of advanced epithelioid sarcoma. However, the effect of tazemetostat on colorectal cancer (CRC) and 5-FU sensitivity remains unclear. In this study, the enhancement of tazemetostat on 5-FU sensitivity was examined in CRC cells. Our findings demonstrated that tazemetostat combined with 5-FU exhibits synergistic antitumor function in vitro and in vivo in CRC cells. In addition, tazemetostat promotes PUMA induction through the ROS/ER stress/CHOP axis. PUMA depletion attenuates the antitumor effect of the combination therapy. Therefore, tazemetostat may be a novel treatment to improve the sensitivity of tumors to 5-FU in CRC therapy. In conclusion, the combination of 5-FU and tazemetostat shows high therapeutic possibility with reduced unfavorable effects.

Abstract PO-008: Bithioether Stapled Peptides as Allosteric Inhibitors of PRC2 function

Abstract Cancer is a genetic disease, but its development also involves multiple epigenetic alterations. Epigenetics regulates transcription by modulating chromatin architecture through different mechanisms. Hence, dysregulation of such mechanisms can result in aberrant gene expression or silencing, which in turn can lead to carcinogenesis. One of the most relevant epigenetic modifications is the methylation of lysine 27 at histone 3 (H3K27), a broadly known repressive histone mark. H3K27 methylation is incorporated by the polycomb repressive complex 2 (PRC2), a multimeric protein complex formed by four core components: EZH2, EED, SUZ12 and RbAp46/48, all of which are essential for its catalytic activity. Overexpression of PRC2 proteins, particularly of EZH2, results in hyperactivation of the complex and high levels of H3K27m3, which are associated to a myriad of human cancers. Hence, the discovery of PRC2 inhibitors is an area of active research for both the pharmaceutical industry and academic laboratories. The relevance of such compounds is highlighted by the recent accelerated approval of the first in class EZH2 inhibitor (tazemetostat, Epizyme), for the treatment of metastatic or locally advanced epithelioid sarcoma. Recent reports suggest that the interaction in between RbAp46/48 and Suz12 is crucial for both proper PRC2 assembly and function. Based on these structural considerations we have designed a series a stapled peptide inhibitors of the NBE domain of SUZ12, and thus of its association with RbAp46/48, as allosteric inhibitors of the catalytic activity of PRC2. Our lead cyclopeptide showed potent inhibition of H3K27 trimethylation in both in vitro and cellular assays, demonstrating that it is cell permeable and active in physiological conditions. Its inhibition of PRC2 catalytic activity produced a marked dose-dependent antiproliferative effect in metastatic Cakis-1 cells. Notably, in these experiments our compound was almost as effective as GSK126, a well-known orthosteric EZH2 inhibitor. We further present compelling evidences suggesting that our stapled peptide targets selectively PRC2, and more specifically, its catalytic subunit EZH2 in an allosteric fashion. To our knowledge, this bisthioether stapled peptide may well be the first example of such allosteric EZH2 inhibitors described to date. This class of compounds could be extremely valuable in addressing the resistance profiles recently reported in clinical trials with EZH2-SET domain inhibitors, in which extended dosing of these drugs have led to secondary EZH2 mutants resistant to treatment. Our compound’s unique mechanism of PRC2 inhibition, together with its potency, remarkable H3K27me3 inhibition selectivity, and low cytotoxicity to non-cancerous cells demonstrate this stapled peptide’s potential for future development of novel epigenetic cancer therapies. Citation Format: Gan Zhang, Adam Herskovits, Nissim Levy, Guillermo Gerona-Navarro. Bithioether Stapled Peptides as Allosteric Inhibitors of PRC2 function [abstract]. In: Abstracts: AACR Special Virtual Conference on Epigenetics and Metabolism; October 15-16, 2020; 2020 Oct 15-16. Philadelphia (PA): AACR; Cancer Res 2020;80(23 Suppl):Abstract nr PO-008.

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.

Clinical significance of recombinant RANBP2-ALK oncogene to radiotherapy in a case of locally advanced rectal epithelioid inflammatory myofibroblastic sarcoma: case report and review of literature

Clinical significance of recombinant RANBP2-ALK oncogene to radiotherapy in a case of locally advanced rectal epithelioid inflammatory myofibroblastic sarcoma: case report and review of literature

The Promise for Histone Methyltransferase Inhibitors for Epigenetic Therapy in Clinical Oncology: A Narrative Review.

Epigenetic processes are essential for normal development and the maintenance of tissue-specific gene expression in mammals. Changes in gene expression and malignant cellular transformation can result from disruption of epigenetic mechanisms, and global disruption in the epigenetic landscape is a key feature of cancer. The study of epigenetics in cancer has revealed that human cancer cells harbor both genetic alterations and epigenetic abnormalities that interplay at all stages of cancer development. Unlike genetic mutations, epigenetic aberrations are potentially reversible through epigenetic therapy, providing a therapeutically relevant treatment option. Histone methyltransferase inhibitors are emerging as an epigenetic therapy approach with great promise in the field of clinical oncology. The recent accelerated approval of the enhancer of zeste homolog 2 (EZH2; also known as histone-lysine N-methyltransferase EZH2) inhibitor tazemetostat for metastatic or locally advanced epithelioid sarcoma marks the first approval of such a compound for the treatment of cancer. Many other histone methyltransferase inhibitors are currently in development, some of which are being tested in clinical studies. This review focuses on histone methyltransferase inhibitors, highlighting their potential in the treatment of cancer. We also discuss the role for such epigenetic drugs in overcoming epigenetically driven drug resistance mechanisms, and their value in combination with other therapeutic approaches such as immunotherapy.