Tazemetostat in advanced epithelioid sarcoma with loss of INI1/SMARCB1: an international, open-label, phase 2 basket study

EZH2 inhibition and 5-azacytidine enhance antitumor immunity in PTEN-deficient glioblastoma by activation viral mimicry response

BACKGROUND

PTEN-deficient glioblastoma (GBM) is characterized by an immunosuppressive tumor microenvironment (TME), therapeutic resistance, and poor prognosis. Emerging evidence suggests that dysregulation of the endogenous retrovirus (ERV)-MAVS-IFN pathway may contribute to immune evasion in cancer, but its role in PTEN-deficient GBM remains unclear.

METHODS

Using flow cytometry and single-cell RNA sequencing, we analyzed the immune landscape of PTEN-deficient GBM. We evaluated the effects of 5-azacytidine (5-AZA) monotherapy and its combination with EZH2 inhibition (EZH2i) on ERV reactivation, type I interferon (IFN) responses, and TME remodeling. Mechanistic studies focused on H3K27me3-mediated epigenetic regulation of ERV expression.

RESULTS

We found that PTEN deficiency suppresses type I IFN responses by impairing viral mimicry through dysregulation of the ERV-MAVS-IFN pathway, thereby sustaining an immunosuppressive TME. While 5-AZA alone failed to reactivate ERVs or overcome therapeutic resistance, combining it with EZH2i synergistically restored robust type I IFN signaling. This combination therapy reduced H3K27me3 levels, promoting ERV transcriptional activation and enhancing 5-AZA-induced viral mimicry. Consequently, the dual treatment reprogrammed the TME to boost antitumor immunity and suppress tumor progression.

CONCLUSIONS

Our study demonstrates that PTEN-deficient GBM evades immune surveillance by suppressing the ERV-MAVS-IFN axis. The combination of EZH2i and 5-AZA overcomes this resistance by epigenetically reactivating viral mimicry, offering a promising therapeutic strategy to enhance antitumor immunity and improve outcomes in patients with PTEN-deficient GBM.

Epigenetic regulation of histone modifications in glioblastoma: recent advances and therapeutic insights

Glioblastoma (GBM) is the most common primary malignant brain tumor, characterized by its aggressive behavior, limited treatment options, and poor prognosis. Despite advances in surgery, radiotherapy, and chemotherapy, the median survival of GBM patients remains disappointingly short. Recent studies have underscored the critical role of histone modifications in GBM malignant progression and therapy resistance. Histones, protein components of chromatin, undergo various modifications, including acetylation and methylation. These modifications significantly affect gene expression, thereby promoting tumorigenesis and resistance to therapy. Targeting histone modifications has emerged as a promising therapeutic approach. Numerous pre-clinical studies have evaluated histone modification agents in GBM, including histone deacetylase inhibitors and histone methyltransferase inhibitors. These studies demonstrate that modulating histone modifications can alter gene expression patterns, inhibit tumor growth, induce apoptosis, and sensitize tumor cells to conventional treatments. Some agents have advanced to clinical trials, aiming to translate preclinical efficacy into clinical benefit. However, clinical outcomes remain suboptimal, as many agents fail to significantly improve GBM patient prognosis. These challenges are attributed to the complexity of histone modification networks and the adaptive responses of the tumor microenvironment. This review provides a comprehensive overview of epigenetic regulation mechanisms involving histone modifications in GBM, covering their roles in tumor development, tumor microenvironment remodeling, and therapeutic resistance. Additionally, the review discusses current clinical trials targeting histone modifications in GBM, highlighting successes, limitations, and future perspectives.

Effect of Cytochrome P450 3A Inhibition and Induction by Itraconazole and Rifampin on Tazemetostat Pharmacokinetics in Patients With Advanced Malignancies

This study (NCT04537715) investigated itraconazole (strong cytochrome P450 [CYP] 3A inhibitor) and rifampin (strong CYP3A inducer) on tazemetostat pharmacokinetics. In Part 1, patients received tazemetostat 400 mg orally on Days 1, 15, and 36, and 400 mg twice daily on Days 3-14 and Days 21-35. Itraconazole 200 mg orally once daily was administered on Days 18-38. In Part 2, patients received tazemetostat 800 mg orally once daily on Days 1, 15, and 24, and 800 mg twice daily on Days 3-14 and Days 17-23. Rifampin 600 mg orally once daily was administered on Days 17-25. Twenty-one patients in each part completed had plasma concentrations quantified for pharmacokinetic assessments. Itraconazole coadministration resulted in higher tazemetostat exposures after single doses (Day 21/Day 1) and steady state (Day 36/Day 15). Compared with tazemetostat alone, itraconazole increased mean maximum plasma concentration (Cmax) and area under the concentration-time curve from time 0 to 12 hours (AUC0-12h) by 2.00- and 3.12-fold, respectively, after single doses. Following twice-daily dosing, itraconazole increased mean steady-state Cmax and AUC0-12h by 1.86- and 2.47-fold, respectively. Rifampin coadministration decreased tazemetostat steady-state (Cmax) and AUC0-12h by approximately 84% (Day 24/Day 15). Itraconazole increased tazemetostat exposure by 2-3-fold, and rifampin decreased tazemetostat exposure by 84%, indicating that coadministration of tazemetostat with strong CYP3A inhibitors or inducers should be avoided.

Molecular mechanisms of viral oncogenesis in haematological malignancies: perspectives from metabolic reprogramming, epigenetic regulation and immune microenvironment remodeling

Haematological malignancies are one of the most common tumors, with a rising incidence noted over recent decades. Viral infections play significant roles in the pathogenesis of these malignancies globally. This review delves into the contributions of various known viruses-specifically Epstein-Barr virus (EBV), human immunodeficiency virus (HIV), human T-cell leukemia virus type 1 (HTLV-1), Kaposi's sarcoma-associated herpesvirus (KSHV), human cytomegalovirus (HCMV), hepatitis B virus (HBV), hepatitis C virus (HCV), and human papillomavirus (HPV)-in the development of haematological malignancies. These viruses are shown to drive tumorigenesis through mechanisms, such as metabolic reprogramming, epigenetic modifications, and remodeling of the immune microenvironment. By directly disrupting fundamental cellular functions and altering metabolic and epigenetic pathways, these viruses foster an immune milieu that supports both viral persistence and tumor growth. A thorough understanding of these viral oncogenic processes is crucial not only for etiological discovery but also for developing targeted interventions. This review emphasizes the need for continued research into the specific ways these viruses manipulate the host cell's metabolic and epigenetic environments, aiming to provide insights that could guide future advancements in treatment modalities.

Extra-Axial Poorly Differentiated Chordoma Initially Misdiagnosed as Epithelioid Sarcoma

Poorly differentiated chordoma is an exceedingly rare, aggressive subtype of chordoma. These tumors typically arise in the axial skeleton of young patients, most commonly the skull base, followed by the cervical spine. Herein, we present a 60-year-old patient with longstanding knee pain and nondiagnostic imaging, initially thought to be due to osteoarthritis. No discrete mass-forming lesion was identified by radiology. Synovial histology at the time of arthroplasty revealed a multinodular proliferation of epithelioid-to-histiocytoid cells with a moderate amount of eosinophilic-to-clear, vacuolated cytoplasm. Scattered cells with high-grade nuclear atypia were present. A diagnosis of metastatic carcinoma was considered due to immunohistochemical positivity for keratin and GATA3. However, a diagnosis of epithelioid sarcoma was rendered based on clinical context, morphology, and loss of immunohistochemical expression for SMARCB1 (INI1). However, upon re-review of the tumor, brachyury was retrospectively added to the immunohistochemistry panel and showed strong positivity, thus prompting amendment of the initial diagnosis of epithelioid sarcoma to extra-axial poorly differentiated chordoma. Given the rarity of this diagnosis, molecular testing was performed which revealed a unique SMARCB1 molecular profile with a single-nucleotide variant in addition to the commonly reported loss of chromosome 22q. This report of an ultra-rare sarcoma in an uncommon anatomic site highlights multiple potential pitfalls in the diagnosis of poorly differentiated chordoma, emphasizes the importance of brachyury immunohistochemistry in rendering a correct interpretation, and underscores an opportunity for further molecular analysis to better define the molecular profile of this entity.

CA-125 as a Biomarker in Renal Medullary Carcinoma: Integrated Molecular Profiling, Functional Characterization, and Prospective Clinical Validation

PURPOSE

Renal medullary carcinoma (RMC) is a highly aggressive malignancy defined by the loss of the SMARCB1 tumor suppressor. It mainly affects young individuals of African descent with sickle cell trait, and it is resistant to conventional therapies used for other renal cell carcinomas. This study aimed to identify potential biomarkers for early detection and disease monitoring of RMC.

EXPERIMENTAL DESIGN

Integrated profiling of primary untreated RMC tumor tissues and paired adjacent kidney controls was performed using RNA sequencing and histone chromatin immunoprecipitation sequencing. The expression of serum cancer antigen 125 (CA-125), was prospectively evaluated in 47 patients with RMC. Functional studies were conducted in RMC cell lines to assess the effects of SMARCB1 reexpression.

RESULTS

MUC16, encoding for CA-125, was identified as one of the top upregulated genes in RMC tissues, with concomitant enrichment of active histone marks H3K4me3 and H3K27ac at its promoter. Elevated serum CA-125 levels were found in 31 of 47 (66%) patients with RMC and correlated significantly with metastatic tumor burden (P = 0.03). Functional studies in RMC cell lines demonstrated that SMARCB1 reexpression significantly reduced MUC16 expression.

CONCLUSIONS

The correlation between serum CA-125 levels and metastatic burden suggests that CA-125 is a clinically relevant biomarker for RMC. These findings support further exploration of CA-125 for disease monitoring and targeted therapeutics in RMC.

EZH1/EZH2 inhibition enhances adoptive T cell immunotherapy against multiple cancer models

Tumor resistance to chimeric antigen receptor T cell (CAR-T) and, in general, to adoptive cell immunotherapies (ACTs) is a major challenge in the clinic. We hypothesized that inhibiting the tumor drivers' methyltransferases EZH2 and EZH1 could enhance ACT by rewiring cancer cells to a more immunogenic state. In human B cell lymphoma, EZH2 inhibition (tazemetostat) improved the efficacy of anti-CD19 CAR-T by enhancing activation, expansion, and tumor infiltration. Mechanistically, tazemetostat-treated tumors showed upregulation of genes related to adhesion, B cell activation, and inflammatory responses, and increased avidity to CAR-T. Furthermore, tazemetostat improved CAR- and TCR-engineered T cell efficacy in multiple liquid (myeloma and acute myeloid leukemia) and solid (sarcoma, ovarian, and prostate) cancers. Lastly, combined EZH1/EZH2 inhibition (valemetostat) further boosted CAR-T efficacy and expansion in multiple cancers. This study shows that EZH1/2 inhibition reprograms tumors to a more immunogenic state and potentiates ACT in preclinical models of both liquid and solid cancers.

Epigenetic targeting of PGBD5-dependent DNA damage in SMARCB1-deficient sarcomas

Despite the potential of targeted epigenetic therapies, most cancers do not respond to current epigenetic drugs. The Polycomb repressive complex EZH2 inhibitor tazemetostat was recently approved for the treatment of SMARCB1-deficient epithelioid sarcomas, based on the functional antagonism between PRC2 and loss of SMARCB1. Through the analysis of tazemetostat-treated patient tumors, we recently defined key principles of their response and resistance to EZH2 epigenetic therapy. Here, using transcriptomic inference from SMARCB1-deficient tumor cells, we nominate the DNA damage repair kinase ATR as a target for rational combination EZH2 epigenetic therapy. We show that EZH2 inhibition promotes DNA damage in epithelioid and rhabdoid tumor cells, at least in part via its induction of the transposase-derived PGBD5. We leverage this collateral synthetic lethal dependency to target PGBD5-dependent DNA damage by inhibition of ATR but not CHK1 using elimusertib. Consequently, combined EZH2 and ATR inhibition improves therapeutic responses in diverse patient-derived epithelioid and rhabdoid tumors in vivo. This advances a combination epigenetic therapy based on EZH2-PGBD5 synthetic lethal dependency suitable for immediate translation to clinical trials for patients.

SMARCB1-deficient poorly differentiated testicular carcinoma: a case report

In the present study, a 36-year-old male presented with left scrotal enlargement without an obvious cause, accompanied by a feeling of heaviness. Imaging examinations revealed a left testicular malignancy, the patient underwent left testicular mass removal,and the postoperative pathology results revealed a highly malignant germ cell tumor, with a tendency toward poorly differentiated embryonal carcinoma or seminoma. After surgery, the condition of the patient deteriorated rapidly, and distant tumor metastasis occurred. Lymph node puncture pathology results revealed poorly differentiated carcinoma consistent with SMARCB1/INI-1 deletion. Despite the use of chemotherapy, radiotherapy, immunotherapy and targeted therapy, the patient died 11 months after surgery. To the best of our knowledge, this is the first case report of a SMARCB1/INI1-deficient Poorly differentiated testicular carcinoma, which is very similar to testicular spermatocytic carcinoma in clinical diagnosis and deserves differentiation for future clinical diagnoses.This report provides important insights into the diagnosis and treatment of SMARCB1/INI1-deficient testicular malignancy. SMARCB1 is a crucial tumor suppressor gene, and its deficiency is closely associated with the development of various malignant tumors. The identification of this case suggests that future research should further explore the molecular mechanisms of SMARCB1-deficient tumors, particularly their role in testicular malignancies. Additionally, the diagnostic process of this case highlights that SMARCB1/INI1-deficient tumors can be clinically very similar to spermatocytic carcinoma of the testis, which can easily lead to misdiagnosis. Therefore, future clinical practice should emphasize the detection of SMARCB1/INI1 expression status, especially in the context of highly aggressive and rapidly progressing testicular malignancies, where immunohistochemical testing for SMARCB1/INI1 should be considered to confirm the diagnosis. In terms of treatment, this case demonstrates the highly aggressive nature and resistance to conventional therapies of SMARCB1/INI1-deficient tumors. Despite the patient receiving multiple treatments, disease progression could not be halted. This underscores the need for the development of novel therapeutic strategies targeting SMARCB1/INI1-deficient tumors, such as combinations of immune checkpoint inhibitors and targeted therapies, or other emerging immunotherapeutic approaches. Moreover, the treatment course of this patient also reflects the importance of individualized treatment plans. Future research should further explore precision medicine strategies based on tumor genetic profiles to improve patient survival rates and quality of life.

Polycomb repressive complex 2 (PRC2) pathway's role in cancer cell plasticity and drug resistance

Polycomb Repressive Complex 2 (PRC2) is a central regulator of gene expression via the trimethylation of histone H3 on lysine 27. This epigenetic modification plays a crucial role in maintaining cell identity and controlling differentiation, while its dysregulation is closely linked to cancer progression. PRC2 silences tumor suppressor genes, promoting cell proliferation, metastasis, epithelial-mesenchymal transition, and cancer stem cell plasticity. Enhancement of zeste homolog 2 (EZH2) overexpression or gain-of-function mutations have been observed in several cancers, including lymphoma, breast, and prostate cancers, driving aggressive tumor behavior and drug resistance. In addition to EZH2, other PRC2 components, such as embryonic ectoderm development (EED) and suppressor of zeste 12, are essential for complex stability and function. EED, in particular, enhances EZH2 activity and has emerged as a therapeutic target. Inhibitors like MAK683 and EED226 disrupt EED's ability to maintain PRC2 activity, thereby reducing H3K27me3 levels and reactivating tumor suppressor genes. Valemetostat, a dual inhibitor of both EZH2 and EED, has shown promising results in aggressive cancers like diffuse large B-cell lymphoma and small-cell lung cancer, underlining the therapeutic potential of targeting multiple PRC2 components. PRC2's role extends beyond gene repression, as it contributes to metabolic reprogramming in tumors, regulating glycolysis and lipid synthesis to fuel cancer growth. Furthermore, PRC2 is implicated in chemoresistance, particularly by modulating DNA damage response and immune evasion. Tazemetostat, a selective EZH2 inhibitor, has demonstrated significant clinical efficacy in EZH2-mutant cancers, such as non-Hodgkin lymphomas and epithelioid sarcoma. However, the compensatory function of enhancer of zeste homolog 1 (EZH1) in some cancers requires dual inhibition strategies, as seen with agents like UNC1999 and Tulmimetostat, which target both EZH1 and EZH2. Given PRC2's multifaceted role in cancer biology, its inhibition represents a promising avenue for therapeutic intervention. The continued development of PRC2 inhibitors and exploration of their use in combination with standard chemotherapy or immunotherapy has great potential for improving patient outcomes in cancers driven by PRC2 dysregulation.

Systemic Treatment in Soft Tissue Sarcomas: Are We Making a Difference?

Soft tissue sarcomas [STSs] are rare tumors of mesodermal origin that arise in diverse tissues such as muscles, fat, and nerves. There are over 100 subtypes of STS, each with distinct clinical behaviors and responses to treatment. Recent advances in treatment have moved towards histology-specific approaches, emphasizing the integration of pathological, immunohistochemical, and molecular features to guide treatment. Localized STS is primarily treated with surgery, often supplemented by neoadjuvant or adjuvant radiation and/or chemotherapy. However, about half of patients with localized disease will progress to an advanced stage, which is typically managed with systemic therapies including anthracycline-based chemotherapy such as doxorubicin or epirubicin. Despite these treatments, the survival rates for most subtypes of advanced metastatic STS remain relatively low. While anthracycline-based chemotherapy remains the mainstay of treatment, ongoing research into the biology of STSs is enhancing our understanding and approach to these complex tumors with an expansion beyond chemotherapy to include targeted therapy and immunotherapy to improve response rates and survival outcomes. This review focuses on STS other than gastrointestinal stromal tumors [GISTs], examines the current systemic treatment strategies, highlights recent advances, and explores future directions in the systemic therapy of sarcoma patients.

From pathogenesis to precision medicine: Transformative advances in research and treatment of ameloblastoma

Odontogenic neoplasms of the jaw are dominated by ameloblastoma (AM), a locally aggressive epithelial tumor with a significant propensity for recurrence. The World Health Organization's 2022 update to the AM classification system underscores recent progress in comprehending its underlying mechanisms and refining clinical approaches. Contemporary research has yielded significant insights into the genetic underpinnings of AM, paving the way for the development of precision-based treatment strategies. Advanced genetic profiling has revealed a significant frequency of BRAF (V-raf murine sarcoma viral oncogene homolog) V600E and SMO (Smoothened) gene alterations in AM. Importantly, therapeutic interventions specifically designed to target these genetic aberrations, including BRAF and MEK pathway blockers, have shown encouraging results in terms of both effectiveness and tolerability, as documented in individual case reports and small-scale clinical investigations. This comprehensive review summarizes the recent modifications to the World Health Organization's categorization of AMs, explores progress in elucidating their underlying molecular pathways, and evaluates emerging targeted treatment modalities. Our objective is to present a thorough synthesis of contemporary scientific discoveries and therapeutic interventions, potentially paving the way for more efficacious and individualized clinical management protocols for this complex neoplasm.

Bioavailability, Metabolism, and Excretion of [14C]-Tazemetostat in Patients With B-Cell Lymphomas or Advanced Solid Tumors

This open-label, multicenter study (NCT03010982) evaluated the absolute bioavailability, characterized the disposition and metabolism, and investigated the metabolic profile of tazemetostat, a US Food and Drug Administration-approved inhibitor of enhancer of zeste homolog 2, following intravenous and oral [14C]-labeled and unlabeled tazemetostat in patients with B-cell lymphomas or advanced solid tumors. Patients received oral tazemetostat 800 mg twice daily for 14 days. On Day 15, patients received tazemetostat 800-mg tablets in a fasted state followed by an intravenous microdose of 12 µg [14C]-tazemetostat. On Day 16, patients received a [14C]-tazemetostat 800-mg solution with a meal, then continued tazemetostat 800 mg twice daily. Blood, plasma, urine, and fecal samples were collected for pharmacokinetic analyses, and recovery and excretion of the radioactivity of [14C]-labeled/unlabeled tazemetostat and its metabolites. The median absolute bioavailability was 31.8% (range, 20.2%-49.8%). Notable plasma components were EPZ-6930, unchanged tazemetostat, EPZ006931, and EPZ034163, accounting for 31.8%, 22.4%, 11.0%, and 3.5% of total drug-related exposure, respectively. Recovery of radiolabeled material ranged from 93.2% to 94.7%, with most excreted doses recovered within 48 hours in urine and by 96 hours in feces. Fecal elimination represented the principal route of elimination with a mean of 78.9% of the administered radioactive dose and renal excretion accounted for 15.4%.

Characterizing Cardiotoxicity of FDA-Approved Soft Tissue Sarcoma Targeted Therapies and Immune Checkpoint Inhibitors: A Systematic Review

Background: Soft tissue sarcomas (STS) are aggressive cancers that show increasing response to novel targeted-therapies and immune-checkpoint-inhibitors. Despite anecdotal reports of cardiovascular adverse events (AEs) and major adverse cardiovascular events (MACE) potentially hindering their utility, the true cardiotoxic profile of these novel-therapies in STS has been largely understudied. Methods: We assessed the incidence and severity of AEs and MACE of contemporary FDA-approved targeted and immune-based therapies for STS, using data from landmark clinical trials supporting FDA-approval. We also analyzed data from the FDA adverse-event-reporting-system-(FAERS) for FDA-approved STS targeted and immune-based therapies for comparative real-world validation. Results: Overall, 12 clinical trials supporting FDA-approval of STS targeted-therapies and immune-checkpoint-inhibitors, incorporating 1249 patients, were identified. These clinical trials revealed 751 AEs including, hypertension (382, 50.87%), atrial fibrillation (3, 0.40%), myocardial infarction (2, 0.27%), cardiac failure (congestive included) (9, 1.20%), and cardiac failure (heart failure included) (7, 0.93%). Compared to placebo, those treated saw higher MACE (OR: 3.27, p < 0.001). The FAERS data showed 489 reported AEs including hypertension (275, 56.24%), atrial fibrillation (31, 6.34%), myocardial infarction (15, 3.07%), and cardiac failure (congestive included) (30, 6.13%). Programmed death-ligand 1 (PD-L1) inhibitors had the highest probability of AEs (0.65, 1.17), followed by tyrosine kinase inhibitors (0.66, 0.11), tropomyosin receptor kinase inhibitors (0.25, 0.13), mammalian target of rapamycin inhibitors (0.21, 0.09), and enhancer of zeste homologue 2 inhibitors (0.11, 0.06). Proportions were calculated from the samples in clinical trials supporting FDA-approval and FAERS, respectively. Conclusions: In this investigation, contemporary FDA-approved therapies for STS are associated with increased risk of AEs.

Epigenetic drugs in cancer therapy

Genetic and epigenetic modifications of DNA are involved in cancer initiation and progression. Epigenetic modifications change chromatin structure and DNA accessibility and thus affect DNA replication, DNA repair and transcription. Epigenetic modifications are reversible and include DNA methylation, histone acetylation and histone methylation. DNA methylation is catalysed by DNA methyltransferases, histone acetylation and deacetylation are catalysed by histone acetylases and deacetylases, while histone methylation is catalysed by histone methyltransferases. Epigenetic modifications are dysregulated in several cancers, making them cancer therapeutic targets. Epigenetic drugs (epi-drugs) which are inhibitors of epigenetic modifications and include DNA methyltransferase inhibitors (DNMTi), histone deacetylase inhibitors (HDACi), histone methyltransferase inhibitors (HMTi) and bromodomain and extra-terminal motif protein inhibitors (BETi), have demonstrated clinical success as anti-cancer agents. Furthermore, the combination of epi-drugs with standard chemotherapeutic agents has demonstrated promising anti-cancer effects in pre-clinical and clinical settings. In this review, we discuss the role of epi-drugs in cancer therapy and explore their current and future use in combination with other anti-cancer agents used in the clinic. We further highlight the side effects and limitations of epi-drugs. We additionally discuss novel delivery methods and novel tumour epigenetic biomarkers for the screening, diagnosis and development of personalised cancer treatments, in order to reduce off-target toxicity and improve the specificity and anti-tumour efficacy of epi-drugs.

Ossifying fibromyxoid tumours: A case series

BACKGROUND

Ossifying fibromyxoid tumour is a rare mesenchymal soft tissue sarcoma with uncertain differentiation and variable metastatic potential.

PATIENTS AND METHODS

This study offers a retrospective analysis of 23 patients diagnosed with OFMT between 1993 and 2024.

RESULTS

The tumours most commonly arose in the extremities and trunk, with all patients undergoing surgical resection of the primary tumour. Immunohistochemical analysis frequently revealed the expression of S100 protein and desmin, while next-generation sequencing identified PHF1 rearrangements in 83 % of patients with available NGS, notably PHF1::EP400 and PHF1::TFE3 fusions. Five patients experienced local recurrence, and four developed metastatic disease. There is no prospective data to guide decision making with regards to systemic therapy, and doxorubicin-based regimens demonstrate limited efficacy. However, the potential role of epigenetic dysregulation in OFMT tumorigenesis opens exciting avenues for treatment. In this cohort, one patient exhibited a remarkably durable response to a combination of gemcitabine, which inhibits DNA methylation, and dacarbazine, following rapid tumour progression on doxorubicin.

CONCLUSIONS

Given the limited clinical experience with OFMT, multidisciplinary tumour boards are crucial for tailoring individualized treatment strategies. This study contributes to the growing body of literature on OFMT, providing a foundation for future research.

Roles and mechanisms of histone methylation in vascular aging and related diseases

The global aging trend has posed significant challenges, rendering healthcare for older adults a crucial focus in medical research. Among the numerous health concerns related to aging, vascular aging and dysfunction are important risk factors and underlying causes of age-related diseases. Histone methylation and demethylation, which are involved in gene expression and cellular senescence, are closely associated with the occurrence and development of vascular aging. Consequently, this review aimed to identify the role of histone methylation in the pathogenesis of vascular aging and its potential for treating age-related vascular diseases and provided new insights into therapeutic strategies targeting the vascular system.

Relapse-free survival in a pediatric patient with recurrent EZH2-mutant melanoma treated with adjuvant tazemetostat

Enhancer of zeste homolog 2 (EZH2) is an essential epigenetic regulator of H3K27 histone methylation and is mutated or overexpressed in a wide variety of cancers. In melanoma, EZH2 overexpression contributes to excessive trimethylation of H3K27 on tumor suppressor genes and has been proposed to be a mechanism of tumor progression and metastasis. EZH2-targeted therapies have been successfully used to treat patients with follicular lymphoma and epithelioid sarcoma, but their clinical use in melanoma has not been described. Here, we describe a pediatric patient with multiply relapsed melanoma harboring an EZH2 A692V missense mutation, treated adjuvantly with the EZH2 inhibitor tazemetostat, who experienced a prolonged relapse-free survival.

A first-in-human phase 1/2 dose-escalation study of MAK683 (EED inhibitor) in patients with advanced malignancies

PURPOSE

MAK683, a first-in-class and highly selective allosteric inhibitor of the embryonic ectoderm development subunit of polycomb repressive complex 2, has shown sustained antitumor activity in tumor xenograft models. This first-in-human phase 1/2 study evaluated the safety, pharmacokinetics (PK), and clinical activity of single-agent MAK683 in advanced malignancies.

METHODS

MAK683 was administered fasted once daily or twice daily continuously in 28-day treatment cycles. Safety assessments included the nature of dose-limiting toxicities (DLTs) and the incidence and severity of adverse events (AEs) and serious AEs. The PK profile of MAK683 was assessed in sequential blood samples of cycles 1-6, and pharmacodynamic profiles were measured by H3K27me3 changes from baseline.

RESULTS

Overall, 139 patients (clear cell carcinoma of the ovary [CCCO], 9 [6.5%]; castration-resistant prostate cancer [CRPC], 22 [15.8 %]; diffuse large B-cell lymphoma [DLBCL], 31 [22.3%]; epithelioid sarcoma [ES], 17 [12.2 %]; gastric cancer [GC], 37 [26.6 %]; nasopharyngeal carcinoma [NPC], 17 [12.2 %]; SWI/SNF-mutated sarcoma, 6 [4.3 %]) received MAK683. Median duration of exposure was 57 days (range: 4-1006). Fifteen patients experienced 22 DLTs including thrombocytopenia (4.9 %) and febrile neutropenia (3.3 %). MAK683-related AEs were reported in 98 patients (70.5 %); 43 patients had grade 3/4 drug-related AEs, including neutropenia, thrombocytopenia, and anemia. MAK683 was quickly absorbed, with peak plasma concentrations ranging from 0.975 to 4.08 h. Median progression-free survival was 1.9 months (90 % confidence interval [CI]: 1.8-2.3), and overall response rate was 5.8 % (90 % CI: 2.52-11.03 %). Clinical activity was observed in patients with advanced DLBCL and ES.

CONCLUSION

Overall, MAK683 treatment was well tolerated, and clinical activity was observed in patients with advanced DLBCL and ES.

CLINICAL TRIAL INFORMATION

NCT02900651.

"From Drowning to Treading Water": Adolescents and Young Adults Living with Incurable and Indolent Metastatic Soft Tissue Sarcoma for More than Two Years

INTRODUCTION

Adolescent/young adult (AYA) patients with metastatic soft tissue sarcoma (STS) typically face a dismal prognosis. However, a subset of patients with incurable disease lives beyond two years. Due to the rarity of diagnoses and inherent heterogeneity within this population, a paucity of data exists regarding the experiences of AYAs with an indolent course (and how to best capture these experiences). With increasing biological insight and clinical experience, including the use of targeted or immune therapies, it is anticipated that more such patients will experience prolonged survival. Our pilot study aimed to describe the clinical characteristics and illness experiences of AYAs with incurable yet indolent metastatic STS who were living two years after their diagnoses. Our exploratory aim was to generate a conceptual framework that could subsequently be tested in a multi-center study with a larger cohort of patients.

MATERIALS AND METHODS

Patients with metastatic incurable STS, aged 15-39 years at diagnosis, and at least two years from diagnosis, were eligible. Patients were recruited over a two-year period at a quaternary children's hospital with a comprehensive AYA oncology program. Participants completed a demographic form and PROMIS short form questionnaires for seven domains and answered an open-ended question. Responses to open-ended questions were coded independently by two authors and utilized to generate themes. Clinical variables were collected from medical records.

RESULTS

Five patients completed questionnaires. Mean age was 29.4 years (18.5-39.8 years) at diagnosis and 34 years (23.2-45.7 years) at study. Three patients were female; two were male; four were White; and one was Black/African American. Diagnoses included ASPSCR1::TFE3 alveolar soft part sarcoma; WWTR1::CAMTA1 epithelioid hemangioendothelioma; INI-1 deficient epithelioid sarcoma; EWSR1::NR4A3 extra-skeletal myxoid chondrosarcoma; and low-grade ARHGAP23::FER spindle cell malignancy, a novel fusion-driven sarcoma. Mean time since diagnosis was 4.5 years (2.6-6 years), and mean treatment duration was 4.2 years (1.5-6 years). On average, patients received 4.8 lines (range 2-8 lines) of antineoplastic therapy. All patients received at least one targeted therapy or immune checkpoint inhibitor. Patients reported increased fatigue and anxiety and decreased physical function compared to the standardized US reference population. Themes emerging from qualitative responses included managing physical symptoms, navigating feelings of guilt and inadequacy, self-reflection generating gratitude, and changing illness experiences over time.

CONCLUSIONS

AYA patients living with incurable metastatic soft tissue sarcoma for more than two years were treated with multiple lines of antineoplastic therapy longitudinally. PROMIS data identified fatigue, anxiety, and decreased physical function within this population. Exploratory thematic analysis of qualitative responses generated concepts that could be further tested in an expanded cohort of patients.

Safety profile of EZH2 inhibitors for cancer: a systematic review and meta-analysis

Objective

To evaluate the safety profiles of EZH2-targeted inhibitors in cancer treatment, focusing on treatment-related adverse events (TRAEs) across various clinical trials.

Methods

We conducted a systematic review and meta-analysis using data from clinical trials involving EZH2 inhibitors reported up to May 31, 2024. Databases searched included PubMed, Embase, CENTRAL (Cochrane Central Register of Controlled Trials), and ClinicalTrials.gov. Studies included were those involving patients treated with EZH2 inhibitors as monotherapy or in combination, specifically detailing the incidence of TRAEs. Data on all-grade TRAEs, grade 3 or higher TRAEs, and severe TRAEs were extracted and analyzed using random-effects models.

Results

Our systematic review and meta-analysis included 22 studies encompassing 1,002 patients who met the inclusion criteria. TRAEs were commonly observed during EZH2 inhibitor therapy, affecting 86% of patients (95% CI [79-94%]%; I2 = 89.5%). The incidence of grade 3 or higher TRAEs was 33% (95% CI [21-44%]; I2 = 93.5%), while severe TRAEs occurred in 15% of the cases (95% CI [9-22%]; I2 = 87.5%). The most frequently reported grade 3 or higher TRAEs in the pooled analysis were neutropenia (8%), thrombocytopenia (8%), and anemia (6%). Specifically, for tazemetostat, the most common grade 3 or higher TRAE was neutropenia (5%). For SHR2554, the most prevalent grade 3 or higher TRAEs were thrombocytopenia (17%), neutropenia (8%), and anemia (7%). Notably, treatment-related fatalities were rare, with only 0.9% of patients experiencing potentially fatal outcomes due to therapy.

Conclusion

EZH2 inhibitors demonstrate a manageable safety profile with a low incidence of severe TRAEs, emphasizing their potential as safe therapeutic options in cancer treatment. The low rate of severe TRAEs and the rare occurrences of treatment-related deaths support the continued clinical use and further investigation of EZH2 inhibitors.

Tazemetostat, a Selective EZH2 Inhibitor, in Combination with Pembrolizumab for Recurrent or Metastatic Head and Neck Squamous Cell Carcinoma: A Phase 1 Trial

Objectives: The primary aim of this phase 1 trial is to establish the recommended phase 2 dose (RP2D) of tazemetostat given with a fixed dose of pembrolizumab in patients with recurrent or metastatic head and neck squamous cell carcinomas (RM-HNSCCs). Methods: A 3 + 3 dose-escalation phase 1 design was used to assess three dose-levels of tazemetostat (400, 600, and 800 mg orally, twice daily) with pembrolizumab (200 mg intravenously). Cycle 1 was 35 days (tazemetostat days 1-35; pembrolizumab day 15). Subsequent cycles were 21 days (tazemetostat days 1-21; pembrolizumab day 1). Dose-limiting toxicity (DLT), assessed during cycle 1, was defined as study-drug-related grade 4 neutropenia or thrombocytopenia, grade 3 febrile neutropenia, or grade 3-4 non-hematologic adverse events (AEs). Patients had to have completed cycle 1 to be evaluable for the DLT assessment; otherwise, an equal number of additional patients were enrolled. The RP2D was defined as the highest dose level in which zero of three or less than or equal to one of six patients experienced a DLT. Results: Twelve patients were enrolled: three on 400 mg, three on 600 mg, and six on the 800 mg dose level of tazemetostat. Three patients on the 800 mg dose level did not complete cycle 1 and were not evaluable for DLT. In the other nine patients, DLTs did not occur during cycle 1. In all 12 patients, the most common AEs included anemia (10 patients), fatigue (eight), and hyponatremia (seven). Conclusions: Among the patients with RM-HNSCCs, the RP2D of tazemetostat was 800 mg and administered twice daily when given with pembrolizumab.

A novel case of glial transdifferentiation in renal medullary carcinoma brain metastasis

Renal medullary carcinoma is a rare undifferentiated tumor of the kidney associated with sickle cell trait and characterized by INI1 (SMARCB1) loss. Although metastasis to lungs, lymph nodes, and bone is commonly reported, distant spread to the central nervous system almost never occurs. Here we present an unusual case of a patient with renal medullary carcinoma with metastasis to the brain following treatment which included tazemetostat, an EZH2 inhibitor. The metastatic brain lesion harbored morphologic, immunohistochemical, and methylation profile supportive of a primary CNS phenotype with loss of the trimethylated lysine 27 residue of histone 3 while maintaining INI1 loss and a specific gene fusion shared with the patient's tumor prior to initiation of tazemetostat therapy. Therefore, given the common genetic signatures in the brain metastasis and the patient's prior tumor, this case represents a rare event of glial transdifferentiation in a brain metastasis of renal medullary carcinoma following the use of an epigenetic modulator. As renal medullary carcinoma has been known to cleverly utilize adaptive mechanisms for survival, we propose that such cell plasticity seen in this case may have been provoked by the use of a drug that alters the epigenetic signature of the tumor cells. Thus, careful assessment of tumor biology following novel therapeutic treatment options must be performed in order to note such unexpected consequences of treatment.

Genetic and epigenetic characterization of sarcoma stem cells across subtypes identifies EZH2 as a therapeutic target

High-grade soft tissue sarcomas (STS) are a heterogeneous and aggressive set of cancers. Failure to respond anthracycline chemotherapy, standard first-line treatment, is associated with poor outcomes. We investigated the contribution of STS cancer stem cells (STS-CSCs) to doxorubicin resistance. We identified a positive correlation between CSC abundance and doxorubicin IC50. Utilizing patient-derived samples from five sarcoma subtypes we investigated if a common genetic signature across STS-CSCs could be targeted. We identified Enhancer of Zeste homolog 2 (EZH2), a member of the polycomb repressive complex 2 (PRC2) responsible for H3K27 methylation as being enriched in CSCs. EZH2 activity and a shared epigenetic profile was observed across subtypes and targeting of EZH2 ablated the STS-CSC population. Treatment of doxorubicin-resistant cell lines with tazemetostat resulted in a decrease in the STS-CSC population. These data confirm the presence of shared genetic programs across distinct subtypes of CSC-STS that can be therapeutically targeted.

SarkoLife: quality of life in patients undergoing multimodal soft tissue sarcoma treatment

OBJECTIVE

To assess the tolerability of multimodal therapy in soft tissue sarcoma patients, particularly with regard to their quality of life and level of distress.

MATERIALS AND METHODS

A retrospective cohort study enrolled individuals receiving sarcoma therapy at the sarcoma center of the University of Tuebingen between 2017 and 2022. Participants completed an online survey that included the EORTC's questionnaire (QLQ-C30), coupled with the distress thermometer and demographic inquiries. The primary emphasis was on comparing three distinct modalities: Radiation, Chemotherapy and Surgery. The data were analysed performing one-way ANOVA.

RESULTS

A total of 237 patients were included in the study. There was a significant difference (p < 0.001) in quality of life according to the EORTC scores (high score = high quality of life) between the different treatments: chemotherapy (mean: 26.8 [standard deviation: 19.5]), radiotherapy (51.0 [21.5]), and surgery (46.9 [28.3]). Similarly, a statistically significant discrepancy (p < 0.001) was found in average distress levels (high score = high level of distress) corresponding to each treatment type: radiation (5.0 [2.7]), surgery (6.0 [2.9]), and chemotherapy (7.4 [2.4]). The rates of patients willing to undergo the same treatment varied across groups, with the highest percentage observed in the surgery group (94.2%), followed by radiation (87.4%), and chemotherapy (73.5%).

CONCLUSION

Patients receiving multimodal therapy for soft tissue often find chemotherapy particularly demanding. Impairment of both quality of life and physical well-being is more likely and tends to be more severe compared with radiation or surgery. These observations should be taken into consideration when consenting patients and offering treatment plans.

Exploring oncogenic roles and clinical significance of EZH2: focus on non-canonical activities

The enhancer of zeste homolog 2 (EZH2) is a catalytic component of Polycomb repressive complex 2 (PRC2) mediating the methylation of histone 3 lysine 27 (H3K27me3) and hence the epigenetic repression of target genes, known as canonical function. Growing evidence indicates that EZH2 has non-canonical roles that are exerted as PRC2-dependent and PRC2-independent methylation of non-histone proteins, and methyltransferase-independent interactions of EZH2 with various proteins contributing to gene expression regulation and alterations in the protein stability. EZH2 is frequently mutated and/or its expression is deregulated in various cancer types. The cancer sensitivity to inhibitors of EZH2 enzymatic activity and state-of-the-art approaches to deplete EZH2 with chemical degraders are discussed. This review also presents the clinical trials in various phases that evaluate the use of EZH2 inhibitors, both as monotherapy and in combination with other agents for the treatment of patients with diverse types of cancers.

Outcomes of SWI/SNF complex-deficient sinonasal carcinomas in a Southeast Asian cohort

BACKGROUND

SWI/SNF complex-deficient sinonasal carcinomas are rare, genetically distinct, and aggressive entities.

METHODS

SMARCB1 and SMARCA4 immunohistochemistry was retrospectively performed on a cohort of undifferentiated, poorly differentiated, and poorly defined sinonasal carcinomas. Survival outcomes were compared between SMARCB1/SMARCA4 (SWI/SNF complex)-deficient and -retained groups.

RESULTS

Eight SWI/SNF complex-deficient (six SMARCB1-deficient, two SMARCA4-deficient) cases were identified among 47 patients over 12 years. Triple-modality treatment was more frequently utilized in SWI/SNF complex-deficient carcinomas than in SWI/SNF complex-retained carcinomas (71.4% vs. 11.8%, p = 0.001). After a median follow-up of 21.3 (IQR 9.9-56.0) months, SWI/SNF complex-deficient sinonasal carcinomas showed comparable recurrence rates (57.1% vs. 52.9%, p = 0.839), time-to-recurrence (7.3 [IQR 6.6-8.3] vs. 9.1 [IQR 3.9-17.4] months, p = 0.531), and overall survival (17.7 [IQR 11.8-67.0] vs. 21.6 [IQR 8.9-56.0] months, p = 0.835) compared to SWI/SNF complex-retained sinonasal carcinomas.

CONCLUSION

Triple-modality treatment may improve survival in SWI/SNF complex-deficient sinonasal carcinomas.

Recent Advances in enhancer of zeste homolog 2 Inhibitors: Structural insights and therapeutic applications

Enhancer of Zeste Homolog 2 (EZH2) is overexpressed in many malignancies and plays a critical role in cancer progression. Therefore, it is considered a promising target for therapeutic intervention. Although several EZH2 inhibitors have entered clinical trials, only one has received FDA approval. In this review, we focus on the latest advancements in highly selective and potent dual-targeting EZH2 inhibitors, as well as proteolysis-targeted chimeras (PROTACs) and hydrophobic tagging (HYT) degraders. These novel compounds have been developed to address the existing gaps in the management of abnormal EZH2 expression. Notably, EZH2 inhibitors have shown great efficacy in antitumor therapy and have also demonstrated promising results in antiviral, anti-inflammatory, antisclerotic, bone protection, and nerve injury pain applications. The insights gained from this analysis could provide valuable guidance for future drug design and optimization of EZH2 inhibitors, potentially expediting the discovery of new inhibitors or degraders targeting EZH2.

UK guidelines for the management of soft tissue sarcomas

Soft tissue sarcomas (STS) are rare tumours arising in mesenchymal tissues and can occur almost anywhere in the body. Their rarity, and the heterogeneity of subtype and location, means that developing evidence-based guidelines is complicated by the limitations of the data available. This makes it more important that STS are managed by expert multidisciplinary teams, to ensure consistent and optimal treatment, recruitment to clinical trials, and the ongoing accumulation of further data and knowledge. The development of appropriate guidance, by an experienced panel referring to the evidence available, is therefore a useful foundation on which to build progress in the field. These guidelines are an update of the previous versions published in 2010 and 2016 [1, 2]. The original guidelines were drawn up by a panel of UK sarcoma specialists convened under the auspices of the British Sarcoma Group (BSG) and were intended to provide a framework for the multidisciplinary care of patients with soft tissue sarcomas. This iteration of the guidance, as well as updating the general multidisciplinary management of soft tissue sarcoma, includes specific sections relating to the management of sarcomas at defined anatomical sites: gynaecological sarcomas, retroperitoneal sarcomas, breast sarcomas, and skin sarcomas. These are generally managed collaboratively by site specific multidisciplinary teams linked to the regional sarcoma specialist team, as stipulated in the recently published sarcoma service specification [3]. In the UK, any patient with a suspected soft tissue sarcoma should be referred to a specialist regional soft tissues sarcoma service, to be managed by a specialist sarcoma multidisciplinary team. Once the diagnosis has been confirmed using appropriate imaging and a tissue biopsy, the main modality of management is usually surgical excision performed by a specialist surgeon, combined with pre- or post-operative radiotherapy for tumours at higher risk for local recurrence. Systemic anti-cancer therapy (SACT) may be utilised in cases where the histological subtype is considered more sensitive to systemic treatment. Regular follow-up is recommended to assess local control, development of metastatic disease, and any late effects of treatment.

Synthetic lethal strategies for the development of cancer therapeutics

Synthetic lethality is a genetic phenomenon whereby the simultaneous presence of two different genetic alterations impairs cellular viability. Importantly, targeting synthetic lethal interactions offers potential therapeutic strategies for cancers with alterations in pathways that might otherwise be considered undruggable. High-throughput screening methods based on modern CRISPR-Cas9 technologies have emerged and become crucial for identifying novel synthetic lethal interactions with the potential for translation into biologically rational cancer therapeutic strategies as well as associated predictive biomarkers of response capable of guiding patient selection. Spurred by the clinical success of PARP inhibitors in patients with BRCA-mutant cancers, novel agents targeting multiple synthetic lethal interactions within DNA damage response pathways are in clinical development, and rational strategies targeting synthetic lethal interactions spanning alterations in epigenetic, metabolic and proliferative pathways have also emerged and are in late preclinical and/or early clinical testing. In this Review, we provide a comprehensive overview of established and emerging technologies for synthetic lethal drug discovery and development and discuss promising therapeutic strategies targeting such interactions.

Proximal and Classic Epithelioid Sarcomas are Distinct Molecular Entities Defined by MYC/GATA3 and SOX17/Endothelial Markers, Respectively

Epithelioid sarcoma (ES) is a rare tumor hallmarked by the loss of INI1/SMARCB1 expression. Apart from this alteration, little is known about the biology of ES. Despite recent advances in treatment, the prognosis of ES remains unsatisfactory. To elucidate the molecular underpinnings of ES, and to identify diagnostic biomarkers and potential therapeutic vulnerabilities, we performed an integrated omics profiling (RNA sequencing and methylation array) of 24 primary, untreated ESs. Transcriptome and methylome analysis identified 2 distinct molecular clusters that essentially corresponded to the morphologic variants of ES, classic ES (C-ES) and the more aggressive proximal ES (P-ES). The P-ES group was characterized by hyperactivation of GATA3 and MYC pathways, with extensive epigenetic rewiring associated with EZH2 overexpression. Both DNA methylation and gene expression analysis indicated a striking similarity with the "MYC subgroup" of atypical teratoid/rhabdoid tumor, another SMARCB1-deficient tumor, implying a shared molecular background and potential therapeutic vulnerabilities. Conversely, the C-ES group exhibited an endothelial-like molecular profile, with expression of vascular genes and elevated proangiogenic SOX17 signaling. Immunohistochemistry validated the overexpression of the chromatin regulators GATA3 (9/12 vs 0/16) and EZH2 (7/7 vs 2/6) in P-ESs, and of the vascular factors SOX17 (8/8 vs 1/10) and N-cadherin (5/9 vs 0/10) in C-ESs. Therefore, these molecules emerge as potential diagnostic tools to fill the gap represented by the lack of ES subtype-specific biomarkers. In summary, our study shows that P-ES and C-ES represent distinct molecular entities defined by MYC/GATA3 and SOX17/endothelial molecular traits, respectively. Besides providing insights into the biology of ES, our study pinpoints subtype-specific biomarkers and potential therapeutic vulnerabilities.

Epigenomic heterogeneity as a source of tumour evolution

In the past decade, remarkable progress in cancer medicine has been achieved by the development of treatments that target DNA sequence variants. However, a purely genetic approach to treatment selection is hampered by the fact that diverse cell states can emerge from the same genotype. In multicellular organisms, cell-state heterogeneity is driven by epigenetic processes that regulate DNA-based functions such as transcription; disruption of these processes is a hallmark of cancer that enables the emergence of defective cell states. Advances in single-cell technologies have unlocked our ability to quantify the epigenomic heterogeneity of tumours and understand its mechanisms, thereby transforming our appreciation of how epigenomic changes drive cancer evolution. This Review explores the idea that epigenomic heterogeneity and plasticity act as a reservoir of cell states and therefore as a source of tumour evolution. Best practices to quantify epigenomic heterogeneity and explore its various causes and consequences are discussed, including epigenomic reprogramming, stochastic changes and lasting memory. The design of new therapeutic approaches to restrict epigenomic heterogeneity, with the long-term objective of limiting cancer development and progression, is also addressed.

Recent advances in sarcoma therapy: new agents, strategies and predictive biomarkers

Soft tissue and bone sarcomas are a heterogenous group of uncommon mesenchymal tumors with high unmet needs for novel therapeutic and diagnostic strategies. Despite many challenges that persist, innovative therapeutics are emerging. Here we provide a review of the studies presented at the 2024 American Society of Clinical Oncology annual meeting that were focused on sarcoma. There were many outstanding studies that were reported at the meeting. We begin by discussing the clinical studies on soft tissue sarcoma (STS) that included multiple histology subtypes, followed by highlighting developments in cellular therapy, before delving into specific STS histologic subtypes followed by a section covering the studies that were focused on predictive biomarkers. We conclude by discussing the studies in bone sarcomas. Some of the studies discussed here are likely to be practice changing. Some of the early-phase clinical trials have shown encouraging results.

Progress Toward Epigenetic Targeted Therapies for Childhood Cancer

Among the most significant discoveries from cancer genomics efforts has been the critical role of epigenetic dysregulation in cancer development and progression. Studies across diverse cancer types have revealed frequent mutations in genes encoding epigenetic regulators, alterations in DNA methylation and histone modifications, and a dramatic reorganization of chromatin structure. Epigenetic changes are especially relevant to pediatric cancers, which are often characterized by a low rate of genetic mutations. The inherent reversibility of epigenetic lesions has led to an intense interest in the development of epigenetic targeted therapies. Additionally, the recent appreciation of the interplay between the epigenome and immune regulation has sparked interest in combination therapies and synergistic immunotherapy approaches. Further, the recent appreciation of epigenetic variability as a driving force in cancer evolution has suggested new roles for epigenetic therapies in limiting plasticity and resistance. Here, we review recent progress and emerging directions in the development of epigenetic targeted therapeutics and their promise across the landscape of childhood cancers.

Pharmacological Advancements of PRC2 in Cancer Therapy: A Narrative Review

Polycomb repressive complex 2 (PRC2) is known to regulate gene expression and chromatin structure as it methylates H3K27, resulting in gene silencing. Studies have shown that PRC2 has dual functions in oncogenesis that allow it to function as both an oncogene and a tumor suppressor. Because of this, nuanced strategies are necessary to promote or inhibit PRC2 activity therapeutically. Given the therapeutic vulnerabilities and associated risks in oncological applications, a structured literature review on PRC2 was conducted to showcase similar cofactor competitor inhibitors of PRC2. Key inhibitors such as Tazemetostat, GSK126, Valemetostat, and UNC1999 have shown promise for clinical use within various studies. Tazemetostat and GSK126 are both highly selective for wild-type and lymphoma-associated EZH2 mutants. Valemetostat and UNC1999 have shown promise as orally bioavailable and SAM-competitive inhibitors of both EZH1 and EZH2, giving them greater efficacy against potential drug resistance. The development of other PRC2 inhibitors, particularly inhibitors targeting the EED or SUZ12 subunit, is also being explored with the development of drugs like EED 226. This review aims to bridge gaps in the current literature and provide a unified perspective on promising PRC2 inhibitors as therapeutic agents in the treatment of lymphomas and solid tumors.

Pediatric Central Nervous System Embryonal Tumors: Presentation, Diagnosis, Therapeutic Strategies, and Survivorship-A Review

Central nervous system (CNS) embryonal tumors represent a diverse group of neoplasms and have a peak incidence in early childhood. These tumors can be located anywhere within the CNS, and presenting symptoms typically represent tumor location. These tumors display distinctive findings on neuroimaging and are staged using magnetic resonance imaging of the brain and spine as well as evaluation of cerebrospinal fluid. Diagnosis is made based on an integrated analysis of histologic and molecular features via tissue sampling. Risk stratification is based on integration of clinical staging and extent of resection with histologic and molecular risk factors. The therapeutic approach for these tumors is multimodal and includes surgery, chemotherapy, and radiation, tailored to the individual patient factors (including age) and specific tumor type. Comprehensive supportive care including management of nausea, nutrition support, pain, fertility preservation, and mitigation of therapy-related morbidity (including hearing protection) is imperative through treatment of CNS embryonal tumors. Despite advances in therapy and supportive care, the long-term consequences of current treatment strategies are substantial. Integration of less toxic, molecularly targeted therapies and a comprehensive, multidisciplinary approach to survivorship care are essential to improving survival and the overall quality of life for survivors.

Outcomes of SMARCB1-deficient sinonasal carcinoma: Largest single-center cross-sectional study

BACKGROUND

We evaluate outcomes of SMARCB1-deficient sinonasal carcinomas in the largest single-institution study.

METHODS

Retrospective cross-sectional study of patients with SMARCB1-deficient sinonasal carcinoma between 1998 and 2024. Disease-specific survival (DSS) and recurrence-free probability (RFP) at 1 and 5 years were measured by Kaplan-Meier method.

RESULTS

There were 47 patients with a median age of 53. Initial pathological diagnosis was altered in 33%. Twelve (34%) patients received neoadjuvant chemotherapy, with one partial response. Curative surgical approach was undertaken in 73%. Definitive chemoradiation was administered in 20%. DSS at 1 and 5 years was 93% and 45%, respectively. RFP at 1 and 5 years was 73% and 33%, respectively. On multivariate analysis, cranial nerve involvement (p = 0.01 for DSS) remained significantly worse for DSS and overall survival.

CONCLUSIONS

SMARCB1-deficient tumors had limited response to neoadjuvant chemotherapy. Cranial nerve involvement was associated with worse prognosis. Optimal treatment is unclear. Surgery should be offered to patients with resectable disease.

SMARCB1-deficient malignant neoplasm of the pancreas with heterogeneous morphologies that cannot be classified into existing histologic types

A 50-year-old male with a pancreatic tail tumor underwent distal pancreatectomy. At 14 and 27 months after the primary surgery, metachronous liver metastases were identified and partial hepatectomies were performed for each. Pathologic findings of the primary pancreatic tumor were heterogeneous, but they essentially categorized into two components based on their cytologic features: (i) clear cell component and (ii) epithelioid cell component. The metastatic hepatic tumor was entirely composed of the epithelioid cell component. SMARCB1 expression was lost by immunohistochemistry and heterozygous deletion of SMARCB1 was identified by fluorescence in situ hybridization for both the primary and metastatic tumors. Targeted DNA sequencing of a metastatic hepatic tumor sample was performed and SMARCB1 loss was identified. Based on the morphologic, immunohistochemical, and molecular analyzes, the present case was difficult to classify into any of the existing entities. SMARCB1 deficiency might play a key role in the tumorigenesis.

Epigenetics-targeted drugs: current paradigms and future challenges

Epigenetics governs a chromatin state regulatory system through five key mechanisms: DNA modification, histone modification, RNA modification, chromatin remodeling, and non-coding RNA regulation. These mechanisms and their associated enzymes convey genetic information independently of DNA base sequences, playing essential roles in organismal development and homeostasis. Conversely, disruptions in epigenetic landscapes critically influence the pathogenesis of various human diseases. This understanding has laid a robust theoretical groundwork for developing drugs that target epigenetics-modifying enzymes in pathological conditions. Over the past two decades, a growing array of small molecule drugs targeting epigenetic enzymes such as DNA methyltransferase, histone deacetylase, isocitrate dehydrogenase, and enhancer of zeste homolog 2, have been thoroughly investigated and implemented as therapeutic options, particularly in oncology. Additionally, numerous epigenetics-targeted drugs are undergoing clinical trials, offering promising prospects for clinical benefits. This review delineates the roles of epigenetics in physiological and pathological contexts and underscores pioneering studies on the discovery and clinical implementation of epigenetics-targeted drugs. These include inhibitors, agonists, degraders, and multitarget agents, aiming to identify practical challenges and promising avenues for future research. Ultimately, this review aims to deepen the understanding of epigenetics-oriented therapeutic strategies and their further application in clinical settings.

A novel mutation in SMARCB1 associated with adult Coffin-Siris syndrome and meningioma

SMARCB1 encodes a core subunit of the SWI/SNF chromatin remodeling complex, which plays a crucial role in the regulation of gene expression. Germline mutations in the SMARCB1 gene have been linked to early childhood Coffin-Siris syndrome type 3 (CSS3), a rare congenital malformation syndrome characterized by severe developmental delay and intellectual disability. In this study, we report a family of two adult CSS3 patients with a novel missense SMARCB1 mutation (c.1091A>C, p.Lys364Thr) identified through whole-exome sequencing (WES). Both patients exhibit selective difficulties in verbal learning and experience language delays. Additionally, the development of meningioma is confirmed in one of the patients. Mechanistic studies suggest that this missense mutation may abnormally activate the MAPK signaling pathway, which is implicated in the pathogenesis of tumor progression and neurodevelopmental disorders. This is the first reported case of a germline mutation in the SMARCB1 gene associated with both CSS3 and meningioma, thereby expanding the phenotypic spectrum of SMARCB1-related disorders.

Progresses and Pitfalls of Epigenetics in Solid Tumors Clinical Trials

Epigenetic dysregulation has long been recognized as a significant contributor to tumorigenesis and tumor maintenance, impacting all recognized cancer hallmarks. Although some epigenetic drugs have received regulatory approval for certain hematological malignancies, their efficacy in treating solid tumors has so far been largely disappointing. However, recent advancements in developing new compounds and a deeper understanding of cancer biology have led to success in specific solid tumor subtypes through precision medicine approaches. Moreover, epigenetic drugs may play a crucial role in synergizing with other anticancer treatments, enhancing the sensitivity of cancer cells to various anticancer therapies, including chemotherapy, radiation therapy, hormone therapy, targeted therapy, and immunotherapy. In this review, we critically evaluate the evolution of epigenetic drugs, tracing their development from initial use as monotherapies to their current application in combination therapies. We explore the preclinical rationale, completed clinical studies, and ongoing clinical trials. Finally, we discuss trial design strategies and drug scheduling to optimize the development of possible combination therapies.

Inhibiting EZH2 targets atypical teratoid rhabdoid tumor by triggering viral mimicry via both RNA and DNA sensing pathways

Inactivating mutations in SMARCB1 confer an oncogenic dependency on EZH2 in atypical teratoid rhabdoid tumors (ATRTs), but the underlying mechanism has not been fully elucidated. We found that the sensitivity of ATRTs to EZH2 inhibition (EZH2i) is associated with the viral mimicry response. Unlike other epigenetic therapies targeting transcriptional repressors, EZH2i-induced viral mimicry is not triggered by cryptic transcription of endogenous retroelements, but rather mediated by increased expression of genes enriched for intronic inverted-repeat Alu (IR-Alu) elements. Interestingly, interferon-stimulated genes (ISGs) are highly enriched for dsRNA-forming intronic IR-Alu elements, suggesting a feedforward loop whereby these activated ISGs may reinforce dsRNA formation and viral mimicry. EZH2i also upregulates the expression of full-length LINE-1s, leading to genomic instability and cGAS/STING signaling in a process dependent on reverse transcriptase activity. Co-depletion of dsRNA sensing and cytoplasmic DNA sensing completely rescues the viral mimicry response to EZH2i in SMARCB1-deficient tumors.

The oncogenic axis YAP/MYC/EZH2 impairs PTEN tumor suppression activity enhancing lung tumorigenicity

The tumor suppressor PTEN (phosphatase and tensin homolog deleted in chromosome 10) is genetically deleted or downregulated in many cancer types. Loss of PTEN protein expression is frequently found in lung cancer while genetic alterations are less abundant. PTEN expression is regulated at multiple genetic and epigenetic levels and even partial reduction of its expression increases cancer occurrence. We show that YAP and TAZ cooperate with EZH2, and MYC to transcriptionally repress onco-suppressor genes, including PTEN, in non-small cell lung cancer (NSCLC) cells. YAP/TAZ-EZH2-MYC transcriptional regulators form a nuclear complex that represses PTEN transcription, while their combinatorial targeting restores PTEN expression, attenuates NSCLC cell growth, and prevents compensatory responses induced by single treatments. Datasets analysis of NSCLC patients revealed that PTEN expression is negatively correlated to YAP/TAZ, EZH2 and MYC and that low expression of PTEN is predictive of poor prognosis, especially at earlier stages of the disease. These findings highlight the repressive role of the YAP/TAZ-EZH2-MYC axis on tumor-suppressor genes and offer a potential therapeutic strategy for lung cancer patients with low PTEN levels.

CCN6 Suppresses Metaplastic Breast Carcinoma by Antagonizing Wnt/β-Catenin Signaling to Inhibit EZH2-Driven EMT

Metaplastic breast carcinomas (mBrCA) are a highly aggressive subtype of triple-negative breast cancer with histologic evidence of epithelial-to-mesenchymal transition and aberrant differentiation. Inactivation of the tumor suppressor gene cellular communication network factor 6 (CCN6; also known as Wnt1-induced secreted protein 3) is a feature of mBrCAs, and mice with conditional inactivation of Ccn6 in mammary epithelium (Ccn6-KO) develop spindle mBrCAs with epithelial-to-mesenchymal transition. Elucidation of the precise mechanistic details of how CCN6 acts as a tumor suppressor in mBrCA could help identify improved treatment strategies. In this study, we showed that CCN6 interacts with the Wnt receptor FZD8 and coreceptor LRP6 on mBrCA cells to antagonize Wnt-induced activation of β-catenin/TCF-mediated transcription. The histone methyltransferase EZH2 was identified as a β-catenin/TCF transcriptional target in Ccn6-KO mBrCA cells. Inhibiting Wnt/β-catenin/TCF signaling in Ccn6-KO mBrCA cells led to reduced EZH2 expression, decreased histone H3 lysine 27 trimethylation, and deregulation of specific target genes. Pharmacologic inhibition of EZH2 reduced growth and metastasis of Ccn6-KO mBrCA mammary tumors in vivo. Low CCN6 is significantly associated with activated β-catenin and high EZH2 in human spindle mBrCAs compared with other subtypes. Collectively, these findings establish CCN6 as a key negative regulator of a β-catenin/TCF/EZH2 axis and highlight the inhibition of β-catenin or EZH2 as a potential therapeutic approach for patients with spindle mBrCAs.  Significance: CCN6 deficiency drives metaplastic breast carcinoma growth and metastasis by increasing Wnt/β-catenin activation to upregulate EZH2, identifying EZH2 inhibition as a mechanistically guided treatment strategy for this deadly form of breast cancer.

Progress in the clinical development of investigational systemic agents for recurrent and metastatic nasopharyngeal carcinoma

INTRODUCTION

Nasopharyngeal carcinoma (NPC) remains an endemic disease in certain parts of the world, with many patients presenting with advanced disease on diagnosis. Chemotherapy had remained the standard of care with minimal progress made until recent years. This review aims to provide an overview of recent significant breakthroughs and up-and-coming novel strategies in treating this deadly disease.

AREAS COVERED

This review focuses on the latest clinical development of promising investigational agents in the treatment of advanced NPC. These include anti-vascular agents, signaling pathways inhibitors and immunotherapy.

EXPERT OPINION

The addition of immune-checkpoint inhibitors (CPI) to platinum-based chemotherapy has undoubtedly changed the therapeutic landscape of R/M NPC in the first-line setting. This leaves much room for further research on the optimal treatment strategy in subsequent-line settings, likely including the addition of CPI to anti-vascular agents or novel CPI combinations, with or without chemotherapy as a backbone. Other potential approaches include optimal CPI maintenance therapy after first-line CPI-chemotherapy combination. Potential novel agents on the horizons are antibody-drug conjugates, bi-specific antibodies and signaling inhibitors, with several phase II/III studies currently underway.

Epigenetic age acceleration is a distinctive trait of epithelioid sarcoma with potential therapeutic implications

Recently, DNA methylation clocks have been proven to be precise age predictors, and the application of these clocks in cancer tissue has revealed a global age acceleration in a majority of cancer subtypes when compared to normal tissue from the same individual. The polycomb repressor complex 2 plays a pivotal role in the aging process, and its targets have been shown to be enriched in CpG sites that gain methylation with age. This complex is further regulated by the chromatin remodeling complex SWItch/Sucrose Non-Fermentable and its core subunit, notably the tumor suppressor gene SMARCB1, which under physiological conditions inhibits the activity of the polycomb repressor complex 2. Hence, the loss of function of core members of the SWItch/sucrose non-fermentable complex, such as the tumor suppressor gene SMARCB1, results in increased activity of polycomb repressor complex 2 and interferes with the aging process. SMARCB1-deficient neoplasms represent a family of rare tumors, including amongst others malignant rhabdoid tumors, atypical teratoid and rhabdoid tumors, and epithelioid sarcomas. As aging pathways have recently been proposed as therapeutic targets for various cancer types, these tumors represent candidates for testing such treatments. Here, by deriving epigenetic age scores from more than 1000 tumor samples, we identified epigenetic age acceleration as a hallmark feature of epithelioid sarcoma. This observation highlights the potential of targeting aging pathways as an innovative treatment approach for patients with epithelioid sarcoma.

PPARγ and C/EBPα enable adipocyte differentiation upon inhibition of histone methyltransferase PRC2 in malignant tumors

Loss of terminal differentiation is a hallmark of cancer and offers a potential mechanism for differentiation therapy. Polycomb repressive complex 2 (PRC2) serves as the methyltransferase for K27 of histone H3 that is crucial in development. While PRC2 inhibitors show promise in treating various cancers, the underlying mechanisms remain incompletely understood. Here, we demonstrated that the inhibition or depletion of PRC2 enhanced adipocyte differentiation in malignant rhabdoid tumors and mesenchymal stem cells, through upregulation of peroxisome proliferator-activated receptor gamma (PPARG) and CEBPA. Mechanistically, PRC2 directly represses their transcription through H3K27 methylation, as both genes exhibit a bivalent state in mesenchymal stem cells. KO of PPARG compromised C/EBPα expression and impeded the PRC2 inhibitor-induced differentiation into adipocytes. Furthermore, the combination of the PPARγ agonist rosiglitazone and the PRC2 inhibitor MAK683 exhibited a higher inhibition on Ki67 positivity in tumor xenograft compared to MAK683 alone. High CEBPA, PLIN1, and FABP4 levels positively correlated with favorable prognosis in sarcoma patients in The Cancer Genome Atlas cohort. Together, these findings unveil an epigenetic regulatory mechanism for PPARG and highlight the essential role of PPARγ and C/EBPα in the adipocyte differentiation of malignant rhabdoid tumors and sarcomas with a potential clinical implication.

EZH2-Mediated H3K27 Trimethylation in the Liver of Mice Is an Early Epigenetic Event Induced by High-Fat Diet Exposure

BACKGROUND/OBJECTIVES

Methyltransferase EZH2-mediated H3K27me3 is involved in liver inflammation and fibrosis, but its role in hepatic metabolic derangements is not yet clearly defined. We investigated if a high-fat diet (HFD) induced early changes in EZH2 expression and H3K27 me3 in the liver of mice.

METHODS

Five-week-old mice were fed an HFD or a low-fat diet (Control) for 2 weeks (2 W) or 8 weeks (8 W). Body weight was recorded weekly. Glycemia and oral glucose tolerance were assessed at baseline and after 2 W-8 W. Finally, livers were collected for further analysis.

RESULTS

As expected, mice that received 8 W HFD showed an increase in body weight, glycemia, and liver steatosis and an impairment in glucose tolerance; no alterations were observed in 2 W HFD mice. Eight weeks of HFD caused hepatic EZH2 nuclear localization and increased H3 K27me3; surprisingly, the same alterations occurred in 2 W HFD mice livers, even before overweight onset. We demonstrated that selective EZH2 inhibition reduced H3K27me3 and counteracted lipid accumulation in HUH-7 cells upon palmitic acid treatment.

CONCLUSIONS

In conclusion, we point to EZH2/H3K27me3 as an early epigenetic event occurring in fatty-acid-challenged livers both in vivo and in vitro, thus establishing EZH2 as a potential pharmacological target for metabolic derangements.

Translation of oncolytic viruses in sarcoma

Sarcomas are a rare and highly diverse group of malignancies of mesenchymal origin. While sarcomas are generally considered resistant to immunotherapy, recent studies indicate subtype-specific differences in clinical response to checkpoint inhibitors (CPIs) that are associated with distinct immune phenotypes present in sarcoma subtypes. Oncolytic viruses (OVs) are designed to selectively infect and kill tumor cells and induce intratumoral immune infiltration, enhancing immunogenicity and thereby sensitizing tumors to immunotherapy. Herein we review the accumulated clinical data evaluating OVs in sarcoma. Small numbers of patients with sarcoma were enrolled in early-stage OV trials as part of larger solid tumor cohorts demonstrating safety but providing limited insight into the biological effects due to the low patient numbers and lack of histologic grouping. Several recent studies have investigated talimogene laherparepvec (T-VEC), an approved oncolytic herpes simplex virus (HSV-1), in combination therapy regimens in sarcoma patient cohorts. These studies have shown promising responses in heavily pre-treated and immunotherapy-resistant patients associated with increased intratumoral immune infiltration. As new and more potent OVs enter the clinical arena, prospective evaluation in subtype-specific cohorts with correlative studies to define biomarkers of response will be critical to advancing this promising approach for sarcoma therapy.

High Content Screening Assay of Inhibitors of the Legionella Pneumophila Histone Methyltransferase RomA in Infected Cells

Resistance to anti-microbial agents is a world-wide health threat. Thus, there is an urgent need for new treatments. An alternative approach to disarm pathogens consists in developing drugs targeting epigenetic modifiers. Bacterial pathogens can manipulate epigenetic regulatory systems of the host to bypass defences to proliferate and survive. One example is Legionella pneumophila, a Gram-negative intracellular pathogen that targets host chromatin with a specific, secreted bacterial SET-domain methyltransferase named RomA. This histone methyltransferase specifically methylates H3 K14 during infection and is responsible for changing the host epigenetic landscape upon L. pneumophila infection. To inhibit RomA activity during infection, we developed a reliable high-content imaging screening assay, which we used to screen an in-house chemical library developed to inhibit DNA and histone methyltransferases. This assay was optimised using monocytic leukemic THP-1 cells differentiated into macrophages infected with L. pneumophila in a 96- or 384-well plate format using the Opera Phenix (Perkin Elmer) confocal microscope, combined with Columbus software for automated image acquisition and analysis. H3 K14 methylation was followed in infected, single cells and cytotoxicity was assessed in parallel. A first pilot screening of 477 compounds identified a potential starting point for inhibitors of H3 K14 methylation.