Trotabresib, an oral potent bromodomain and extraterminal inhibitor, in patients with high-grade gliomas: A phase I, "window-of-opportunity" study

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.

Direct synthesis of N-trifluoromethyl amides via photocatalytic trifluoromethylamidation

N-CF3 amides are promising targets for pharmaceutical and agrochemistry. Unfortunately, there is a defluorination problem of N-CF3 amine starting materials when using common amide bond formation method. Recently, elegant alternative approaches emerged. However, none have used the well known amidyl radical chemistry to directly prepare N-CF3 amides. We describe here a convenient preparation of N-(N-CF3 imidoyloxy) pyridinium salts and their applications as efficient trifluoromethylamidyl radical precursors in photocatalytic trifluoromethylamidations of (hetero)arenes, alkenes, alkynes, silylenol ethers, and isocyanides. The rapid construction of diverse N-CF3 amides, particularly the synthesis of cyclic N-CF3 amides, demonstrates the uniqueness and flexibility of the method. This method is expected to provide a platform for directly synthesizing N-CF3 amides and to inspire the discovery of more redox molecular systems that can handle challenging trifluoromethylamidations.

Unlocking the Radiosensitizing Potential of MYC Inhibition in Neuroendocrine Malignancies

The MYC family of transcription factors-comprising c-MYC, N-MYC, and L-MYC-plays a pivotal role in oncogenesis, driving cancer progression and resistance to therapy. While MYC proteins have long been considered challenging drug targets due to their intricate structures, recent advances have led to the development of promising inhibitors. This review explores the role of MYC overexpression in promoting radiation therapy resistance in aggressive neuroendocrine malignancies through multiple mechanisms, including increased tumor cell invasion, enhanced DNA damage repair and oxidative stress management, prosurvival autophagy, survival of circulating tumor cells, angiogenesis, awakening from dormancy, and modulation of chronic inflammation and host immunity. Paradoxically, MYC overexpression can also enhance radiosensitivity in certain cancer cells by driving proapoptotic pathways, such as reactive oxygen species-induced DNA damage that overwhelms cellular repair mechanisms, ultimately leading to cell death. Additionally, we provide a comprehensive summary of direct MYC inhibitors, detailing their current stage of preclinical and clinical development as novel anticancer therapeutics. This review highlights the role of MYC in cancer metastasis and radiation therapy resistance while examining the potential of MYC inhibitors as radiosensitizers in adult and pediatric neuroendocrine malignancies, including small cell lung cancer, large cell neuroendocrine lung cancer, Merkel cell carcinoma, neuroendocrine-differentiated prostate cancer, neuroblastoma, central nervous system embryonal tumors, and medulloblastoma.

Design of Selective BRD4 Inhibitors for the Treatment of Autosomal Dominant Polycystic Kidney Disease

Epigenetic modulation plays a pivotal role in restraining tumor progression by governing gene expression and protein function. Autosomal dominant polycystic kidney disease (ADPKD), characterized by neoplastic-like progression, can be managed by inhibiting cyst expansion. Of note, the epigenetic regulator BRD4 has been implicated in ADPKD's development. Our prior research unveiled a class of (pyrazol-3-yl) pyrimidin-4-amine compounds as potent BRD4 inhibitors with additional kinase inhibition, which might induce unwanted biological activities. To address this, this study focused on creating selective BRD4 inhibitors through structure-guided design, minimizing off-target kinase interactions. Specifically, compound 23 emerged as an efficacious and selective BRD4 inhibitor in cellular and embryonic kidney models of ADPKD, along with encouraging outcomes in murine models. Collectively, these results highlight the therapeutic potential of targeted BRD4 inhibition as a safe and efficacious strategy for managing ADPKD.

Targeting lysine acetylation readers and writers

Lysine acetylation is a major post-translational modification in histones and other proteins that is catalysed by the 'writer' lysine acetyltransferases (KATs) and mediates interactions with bromodomains (BrDs) and other 'reader' proteins. KATs and BrDs play key roles in regulating gene expression, cell growth, chromatin structure, and epigenetics and are often dysregulated in disease states, including cancer. There have been accelerating efforts to identify potent and selective small molecules that can target individual KATs and BrDs with the goal of developing new therapeutics, and some of these agents are in clinical trials. Here, we summarize the different families of KATs and BrDs, discuss their functions and structures, and highlight key advances in the design and development of chemical agents that show promise in blocking the action of these chromatin proteins for disease treatment.

Epigenetic reprogramming in pediatric gliomas: from molecular mechanisms to therapeutic implications

Brain tumors in children and adults differ greatly in patient outcomes and responses to radiotherapy and chemotherapy. Moreover, the prevalence of recurrent mutations in histones and chromatin regulatory proteins in pediatric and young adult gliomas suggests that the chromatin landscape is rewired to support oncogenic programs. These early somatic mutations dysregulate widespread genomic loci by altering the distribution of histone post-translational modifications (PTMs) and, in consequence, causing changes in chromatin accessibility and in the histone code, leading to gene transcriptional changes. We review how distinct chromatin imbalances in glioma subtypes impact on oncogenic features such as cellular fate, proliferation, immune landscape, and radio resistance. Understanding these mechanisms of epigenetic dysregulation carries substantial implications for advancing targeted epigenetic therapies.

Updates for newly diagnosed and recurrent glioblastoma: a review of recent clinical trials

PURPOSE OF REVIEW

Glioblastoma (GBM) is the most common and devastating primary malignant brain tumor. We summarize recent advances in radiotherapy, immunotherapy, and targeted therapy approaches for the treatment of newly diagnosed and recurrent glioblastoma. We also introduce ongoing clinical trials.

RECENT FINDINGS

Recent clinical trials have explored multiple novel strategies to treat GBM including the use of oncoviruses, chimeric antigen receptor (CAR) T cell therapy, vaccines, radiotherapy, and novel drug delivery techniques to improves drug penetrance across the blood brain barrier. Approaches to improve drug delivery to brain tumors have the potential to expand treatment options of existing therapies that otherwise have poor brain tumor penetrance. Immunotherapy has been of keen interest in both newly diagnosed and recurrent glioblastoma. Vaccines SurVaxM and DCVax-L have shown initial promise in phase II and III trials, respectively. CAR T cell therapy trials are in their early phases but hold promise in both newly diagnosed and recurrent glioblastoma.

SUMMARY

Although progress to improve outcomes for GBM patients has been modest, multiple novel strategies utilizing combination therapies, focused ultrasound to improve drug delivery, and novel immunotherapies are underway.

BRD4 Degradation Enhanced Glioma Sensitivity to Temozolomide by Regulating Notch1 via Glu-Modified GSH-Responsive Nanoparticles

Temozolomide (TMZ) serves as the principal chemotherapeutic agent for glioma; nonetheless, its therapeutic efficacy is compromised by the rapid emergence of drug resistance, the inadequate targeting of glioma cells, and significant systemic toxicity. ARV-825 may play a role in modulating drug resistance by degrading the BRD4 protein, thereby exerting anti-glioma effects. Therefore, to surmount TMZ resistance and achieve efficient and specific drug delivery, a dual-targeted glutathione (GSH)-responsive nanoparticle system (T+A@Glu-NP) is designed and synthesized for the co-delivery of ARV-825 and TMZ. As anticipated, T+A@Glu-NPs significantly enhanced penetration of the blood-brain barrier (BBB), facilitated drug uptake by glioma cells, and exhibited efficient accumulation in brain tissue. Additionally, T+A@Glu-NPs exhibited augmented efficacy against glioma both in vitro and in vivo through the induction of apoptosis, inhibition of proliferation, and cell cycle arrest. Furthermore, mechanistic exploration revealed that T+A@Glu-NPs degraded the BRD4 protein, leading to the downregulation of Notch1 gene transcription and the inhibition of the Notch1 signaling pathway, thereby augmenting the therapeutic efficacy of glioma chemotherapy. Taken together, the findings suggest that T+A@Glu-NPs represents a novel and promising therapeutic strategy for glioma chemotherapy.

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.

Bromodomain proteins as potential therapeutic targets for B-cell non-Hodgkin lymphoma

BACKGROUND

B-cell non-Hodgkin lymphoma (B-NHL) is the most common type of lymphoma and is significantly heterogeneous among various subtypes. Despite of considerable advancements in treatment strategies for B-NHL, the prognosis of relapsed/refractory patients remains poor.

MAIN TEXT

It has been indicated that epigenetic dysregulation is critically associated with the pathogenesis of most hematological malignancies, resulting in the clinical targeting of epigenetic modifications. Bromodomain (BRD) proteins are essential epigenetic regulators which contain eight subfamilies, including BRD and extra-terminal domain (BET) family, histone acetyltransferases (HATs) and HAT-related proteins, transcriptional coactivators, transcriptional mediators, methyltransferases, helicases, ATP-dependent chromatin-remodeling complexes, and nuclear-scaffolding proteins. Most pre-clinical and clinical studies on B-NHL have focused predominantly on the BET family and the use of BET inhibitors as mono-treatment or co-treatment with other anti-tumor drugs. Furthermore, preclinical models of B-NHL have revealed that BET degraders are more active than BET inhibitors. Moreover, with the development of BET inhibitors and degraders, non-BET BRD protein inhibitors have also been designed and have shown antitumor activities in B-NHL preclinical models. This review summarized the mechanism of BRD proteins and the recent progress of BRD protein-related drugs in B-NHL. This study aimed to collect the most recent evidences and summarize possibility on whether BRD proteins can serve as therapeutic targets for B-NHL.

CONCLUSION

In summary, BRD proteins are critical epigenetic regulatory factors and may be potential therapeutic targets for B-NHL.

Sequential Inhibition of PARP and BET as a Rational Therapeutic Strategy for Glioblastoma

PARP inhibitors (PARPi) hold substantial promise in treating glioblastoma (GBM). However, the adverse effects have restricted their broad application. Through unbiased transcriptomic and proteomic sequencing, it is discovered that the BET inhibitor (BETi) Birabresib profoundly alters the processes of DNA replication and cell cycle progression in GBM cells, beyond the previously reported impact of BET inhibition on homologous recombination repair. Through in vitro experiments using established GBM cell lines and patient-derived primary GBM cells, as well as in vivo orthotopic transplantation tumor experiments in zebrafish and nude mice, it is demonstrated that the concurrent administration of PARPi and BETi can synergistically inhibit GBM. Intriguingly, it is observed that DNA damage lingers after discontinuation of PARPi monotherapy, implying that sequential administration of PARPi followed by BETi can maintain antitumor efficacy while reducing toxicity. In GBM cells with elevated baseline replication stress, the sequential regimen exhibits comparable efficacy to concurrent treatment, protecting normal glial cells with lower baseline replication stress from DNA toxicity and subsequent death. This study provides compelling preclinical evidence supporting the development of innovative drug administration strategies focusing on PARPi for GBM therapy.

Therapeutic targeting of BET bromodomain and other epigenetic acetylrecognition domain-containing factors

Development of cancer therapies targeting chromatin modifiers and transcriptional regulatory factors is rapidly expanding to include new targets and novel targeting strategies. At the same time, basic molecular research continues to refine our understanding of the epigenetic mechanisms regulating transcription, gene expression, and oncogenesis. This mini-review focuses on cancer therapies targeting the chromatin-associated factors that recognize histone lysine acetylation. Recently reported safety and efficacy are discussed for inhibitors targeting the bromodomains of bromodomain and extraterminal domain (BET) family proteins. In light of recent results indicating that the transcriptional regulator BRD4-PTEFb can function independently of BRD4's bromodomains, the clinical trial performance of these BET inhibitors is placed in a broader context of existing and potential strategies for targeting BRD4-PTEFb. Recently developed therapies targeting bromodomain-containing factors within the SWI/SNF (BAF) family of chromatin remodeling complexes are discussed, as is the potential for targeting the bromodomain-containing transcription factor TAF1 and the YEATS acetylrecognition domain-containing factor GAS41. Recent findings regarding the selectivity and combinatorial specificity of acetylrecognition are highlighted. In conclusion, the potential for further development is discussed with a focus on proximity-based therapies targeting this class of epigenetic factors.

Advanced tumor electric fields therapy: A review of innovative research and development and prospect of application in glioblastoma

BACKGROUND

Glioblastoma multiforme (GBM) is an aggressive malignant tumor with a high mortality rate and is the most prevalent primary intracranial tumor that remains incurable. The current standard treatment, which involves surgery along with concurrent radiotherapy and chemotherapy, only yields a survival time of 14-16 months. However, the introduction of tumor electric fields therapy (TEFT) has provided a glimmer of hope for patients with newly diagnosed and recurrent GBM, as it has been shown to extend the median survival time to 20 months. The combination of TEFT and other advanced therapies is a promising trend in the field of GBM, facilitated by advancements in medical technology.

AIMS

In this review, we provide a concise overview of the mechanism and efficacy of TEFT. In addition, we mainly discussed the innovation of TEFT and our proposed blueprint for TEFT implementation.

CONCLUSION

Tumor electric fields therapy is an effective and highly promising treatment modality for GBM. The full therapeutic potential of TEFT can be exploited by combined with other innovative technologies and treatments.

RAPID resistance to BET inhibitors is mediated by FGFR1 in glioblastoma

Bromodomain and extra-terminal domain (BET) proteins are therapeutic targets in several cancers including the most common malignant adult brain tumor glioblastoma (GBM). Multiple small molecule inhibitors of BET proteins have been utilized in preclinical and clinical studies. Unfortunately, BET inhibitors have not shown efficacy in clinical trials enrolling GBM patients. One possible reason for this may stem from resistance mechanisms that arise after prolonged treatment within a clinical setting. However, the mechanisms and timeframe of resistance to BET inhibitors in GBM is not known. To identify the temporal order of resistance mechanisms in GBM we performed quantitative proteomics using multiplex-inhibitor bead mass spectrometry and demonstrated that intrinsic resistance to BET inhibitors in GBM treatment occurs rapidly within hours and involves the fibroblast growth factor receptor 1 (FGFR1) protein. Additionally, small molecule inhibition of BET proteins and FGFR1 simultaneously induces synergy in reducing GBM tumor growth in vitro and in vivo. Further, FGFR1 knockdown synergizes with BET inhibitor mediated reduction of GBM cell proliferation. Collectively, our studies suggest that co-targeting BET and FGFR1 may dampen resistance mechanisms to yield a clinical response in GBM.

From signalling pathways to targeted therapies: unravelling glioblastoma's secrets and harnessing two decades of progress

Glioblastoma, a rare, and highly lethal form of brain cancer, poses significant challenges in terms of therapeutic resistance, and poor survival rates for both adult and paediatric patients alike. Despite advancements in brain cancer research driven by a technological revolution, translating our understanding of glioblastoma pathogenesis into improved clinical outcomes remains a critical unmet need. This review emphasises the intricate role of receptor tyrosine kinase signalling pathways, epigenetic mechanisms, and metabolic functions in glioblastoma tumourigenesis and therapeutic resistance. We also discuss the extensive efforts over the past two decades that have explored targeted therapies against these pathways. Emerging therapeutic approaches, such as antibody-toxin conjugates or CAR T cell therapies, offer potential by specifically targeting proteins on the glioblastoma cell surface. Combination strategies incorporating protein-targeted therapy and immune-based therapies demonstrate great promise for future clinical research. Moreover, gaining insights into the role of cell-of-origin in glioblastoma treatment response holds the potential to advance precision medicine approaches. Addressing these challenges is crucial to improving outcomes for glioblastoma patients and moving towards more effective precision therapies.

BF3 ⋅Et2 O-Catalyzed Selective C-4 Alkylation of Isoquinolin-1(2H)-ones Employing p-Quinone Methides

The direct C-4 alkylation of isoquinolin-1(2H)-one moiety is a challenging transformation in organic synthesis. Here we present a practical and efficient synthesis of C-4 alkylated isoquinolin-1(2H)-ones through conjugate addition of isoquinolin-1(2H)-ones to p-quinone methides for the first time. The process is facilitated by Lewis acid catalysis and this operationally straightforward, mild, metal-free and one-pot transformation provides a wide range of C-4 alkylated isoquinolin-1(2H)-ones at ambient temperature in good to excellent yields.

BRD4: New Hope in the Battle Against Glioblastoma

The BET family proteins, comprising BRD2, BRD3 and BRD4, represent epigenetic readers of acetylated histone marks that play pleiotropic roles in the tumorigenesis and growth of multiple human malignancies, including glioblastoma (GBM). A growing body of investigation has proven BET proteins as valuable therapeutic targets for cancer treatment. Recently, several BRD4 inhibitors and degraders have been reported to successfully suppress GBM in preclinical and clinical studies. However, the precise role and mechanism of BRD4 in the pathogenesis of GBM have not been fully elucidated or summarized. This review focuses on summarizing the roles and mechanisms of BRD4 in the context of the initiation and development of GBM. In addition, several BRD4 inhibitors have been evaluated for therapeutic purposes as monotherapy or in combination with chemotherapy, radiotherapy, and immune therapies. Here, we provide a critical appraisal of studies evaluating various BRD4 inhibitors and degraders as novel treatment strategies against GBM.

BET inhibitor trotabresib in heavily pretreated patients with solid tumors and diffuse large B-cell lymphomas

Bromodomain and extraterminal proteins (BET) play key roles in regulation of gene expression, and may play a role in cancer-cell proliferation, survival, and oncogenic progression. CC-90010-ST-001 (NCT03220347) is an open-label phase I study of trotabresib, an oral BET inhibitor, in heavily pretreated patients with advanced solid tumors and relapsed/refractory diffuse large B-cell lymphoma (DLBCL). Primary endpoints were the safety, tolerability, maximum tolerated dose, and RP2D of trotabresib. Secondary endpoints were clinical benefit rate (complete response [CR] + partial response [PR] + stable disease [SD] of ≥4 months' duration), objective response rate (CR + PR), duration of response or SD, progression-free survival, overall survival, and the pharmacokinetics (PK) of trotabresib. In addition, part C assessed the effects of food on the PK of trotabresib as a secondary endpoint. The dose escalation (part A) showed that trotabresib was well tolerated, had single-agent activity, and determined the recommended phase 2 dose (RP2D) and schedule for the expansion study. Here, we report long-term follow-up results from part A (N = 69) and data from patients treated with the RP2D of 45 mg/day 4 days on/24 days off or an alternate RP2D of 30 mg/day 3 days on/11 days off in the dose-expansion cohorts (parts B [N = 25] and C [N = 41]). Treatment-related adverse events (TRAEs) are reported in almost all patients. The most common severe TRAEs are hematological. Toxicities are generally manageable, allowing some patients to remain on treatment for ≥2 years, with two patients receiving ≥3 years of treatment. Trotabresib monotherapy shows antitumor activity, with an ORR of 13.0% (95% CI, 2.8-33.6) in patients with R/R DLBCL (part B) and an ORR of 0.0% (95% CI, 0.0-8.6) and a CBR of 31.7% (95% CI, 18.1-48.1) in patients with advanced solid tumors (part C). These results support further investigation of trotabresib in combination with other anticancer agents.

Bromodomain and extraterminal protein-targeted probe enables tumour visualisation in vivo using positron emission tomography

Bromodomain and extraterminal (BET) proteins, a family of epigenetic regulators, have emerged as important oncology drug targets. BET proteins have not been targeted for molecular imaging of cancer. Here, we report the development of a novel molecule radiolabelled with positron emitting fluorine-18, [¹⁸F]BiPET-2, and its in vitro and preclinical evaluation in glioblastoma models.

Trotabresib (CC-90010) in combination with adjuvant temozolomide or concomitant temozolomide plus radiotherapy in patients with newly diagnosed glioblastoma

Background

Standard-of-care treatment for newly diagnosed glioblastoma (ndGBM), consisting of surgery followed by radiotherapy (RT) and temozolomide (TMZ), has improved outcomes compared with RT alone; however, prognosis remains poor. Trotabresib, a novel bromodomain and extraterminal inhibitor, has demonstrated antitumor activity in patients with high-grade gliomas.

Methods

In this phase Ib, dose-escalation study (NCT04324840), we investigated trotabresib 15, 30, and 45 mg combined with TMZ in the adjuvant setting and trotabresib 15 and 30 mg combined with TMZ+RT in the concomitant setting in patients with ndGBM. Primary endpoints were to determine safety, tolerability, maximum tolerated dose, and/or recommended phase II dose (RP2D) of trotabresib. Secondary endpoints were assessment of preliminary efficacy and pharmacokinetics. Pharmacodynamics were investigated as an exploratory endpoint.

Results

The adjuvant and concomitant cohorts enrolled 18 and 14 patients, respectively. Trotabresib in combination with TMZ or TMZ+RT was well tolerated; most treatment-related adverse events were mild or moderate. Trotabresib pharmacokinetics and pharmacodynamics in both settings were consistent with previous data for trotabresib monotherapy. The RP2D of trotabresib was selected as 30 mg 4 days on/24 days off in both settings. At last follow-up, 5 (28%) and 6 (43%) patients remain on treatment in the adjuvant and concomitant settings, respectively, with 1 patient in the adjuvant cohort achieving complete response.

Conclusions

Trotabresib combined with TMZ in the adjuvant setting and with TMZ+RT in the concomitant setting was safe and well tolerated in patients with ndGBM, with encouraging treatment durations. Trotabresib 30 mg was established as the RP2D in both settings.