Clinical development of IDH1 inhibitors for cancer therapy

Identification of relevant features using SEQENS to improve supervised machine learning models predicting AML treatment outcome

BACKGROUND AND OBJECTIVE

This study has two main objectives. First, to evaluate a feature selection methodology based on SEQENS, an algorithm for identifying relevant variables. Second, to validate machine learning models that predict the risk of complications in patients with acute myeloid leukemia (AML) using data available at diagnosis. Predictions are made at three time points: 90 days, six months, and one year post-diagnosis. These objectives represent fundamental steps toward the development of a tool to assist clinicians in therapeutic decision-making and provide insights into the risk factors associated with AML complications.

METHODS

A dataset of 568 patients, including demographic, clinical, genetic (VAF), and cytogenetic information, was created by combining data from Hospital 12 de Octubre (Madrid, Spain) and Instituto de Investigación Sanitaria La Fe (Valencia, Spain). Feature selection based on an enhanced version of SEQENS was conducted for each time point, followed by the comparison of four classifiers (XGBoost, Multi-Layer Perceptron, Logistic Regression and Decision Tree) to assess the impact of feature selection on model performance.

RESULTS

SEQENS identified different relevant features for each prediction horizon, with Age, TP53, - 7/7Q, and EZH2 consistently relevant across all time points. The models were evaluated using 5-fold cross-validation, XGBoost achieve the highest average ROC-AUC scores of 0.81, 0.84, and 0.82 for 90-day, 6-month, and 1-year predictions, respectively. Generally, performance remained stable or improved after applying SEQENS-based feature selection. Evaluation on an external test set of 54 patients yielded ROC-AUC scores of 0.72 (90-day), 0.75 (6-month), and 0.68 (1-year).

CONCLUSIONS

The models achieved performance levels that suggest they could serve as therapeutic decision support tools at different times after diagnosis. The selected variables align with the European LeukemiaNet (ELN) 2022 risk classification, and the SEQENS-based feature selection effectively reduced the feature set while maintaining prediction accuracy.

Resistance to immunotherapy in non-small cell lung cancer: Unraveling causes, developing effective strategies, and exploring potential breakthroughs

Over the last two decades, advancements in deciphering the intricate interactions between oncology and immunity have fueled a meteoric rise in immunotherapy for non-small cell lung cancer, typified by an explosive growth of immune checkpoint inhibitors. However, resistance to immunotherapy remains inevitable. Herein we unravel the labyrinthine mechanisms of resistance to immunotherapy, characterized by their involvement of nearly all types of cells within the body, beyond the extrinsic cancer cells, and importantly, such cells are not only (inhibitory or excitatory, or both) signal recipients but also producers, acting in a context-dependent manner. At the molecular level, these mechanisms underlie genetic and epigenetic aberrations, which are regulated by or regulate various protein kinases, growth factors, and cytokines with inherently dynamic and spatially heterogeneous properties. Additionally, macroscopic factors such as nutrition, comorbidities, and the microbiome within and around organs or tumor cells are involved. Therefore, developing therapeutic strategies combined with distinct action informed by preclinical, clinical, and real-world evidence, such as radiotherapy, chemotherapy, targeted therapy, antibody-drug conjugates, oncolytic viruses, and cell-based therapies, may stand as a judicious reality, although the ideality is to overcome resistance point-by-point through a novel drug. Notably, we highlight a realignment of treatment aims, moving the primary focus from eliminating cancer cells -- such as through chemotherapy and radiotherapy -- to promoting immune modulation and underscore the value of regulating various components within the host macro- or micro-environment, as their effects, even if seemingly minimal, can cumulatively contribute to visible clinical benefit when applied in combination with ICIs. Lastly, this review also emphasizes the current hurdles scattered throughout preclinical and clinical studies, and explores evolving directions in the landscape of immunotherapy for NSCLC.

Chondrosarcoma: New Molecular Insights, Challenges in Near-Patient Preclinical Modeling, and Therapeutic Approaches

Chondrosarcoma (CS), the second most common malignant bone tumor after osteosarcoma, accounts for 20-30% of all malignant bone tumors. It mainly affects adults, middle-aged, and elderly people. The CS family includes various entities displaying peculiar biological, genetic, and epigenetic characteristics and clinical behaviors. Conventional CS is the most common subtype. High-grade, dedifferentiated, and mesenchymal CS, as well as unresectable and metastatic CS, exhibit poor prognoses due to their intrinsic resistance to radiotherapy and chemotherapy, underscoring the urgent need for novel therapeutic strategies. CS research is dealing with several challenges. Experimental studies can rely on animal and patient-derived models, but the paucity of representative near-patient preclinical models has hampered predictive drug screening research. This review describes the main clinical and molecular features of CS subtypes, discussing recent data on the genetic alterations and molecular mechanisms involved in CS pathogenesis and progression. The review provides an overview of the current in vitro and in vivo CS models, discusses their advantages and limitations, and highlights the recent efforts in the development of new targeted therapies against CS dependencies, including IDH1/2 mutations, NAD+ dependency, and SIRT1-HIF-2α axis, or exploring DR5 targeting, antiangiogenic therapies, epigenetic drugs, and immunological approaches. All such strategies, in combination with advanced preclinical modeling and personalized multi-omic profiling, hold promise for improving the survival of patients with advanced CS.

Contrast-Enhanced Computed Tomography-Based Machine Learning Radiomics Predicts IDH1 Expression and Clinical Prognosis in Head and Neck Squamous Cell Carcinoma

RATIONALE AND OBJECTIVES

Isocitrate dehydrogenase 1 (IDH1) is a potential therapeutic target across various tumor types. Here, we aimed to devise a radiomic model capable of predicting the IDH1 expression levels in patients with head and neck squamous cell carcinoma (HNSCC) and examined its prognostic significance.

MATERIALS AND METHODS

We utilized genomic data, clinicopathological features, and contrast-enhanced computed tomography (CECT) images from The Cancer Genome Atlas and the Cancer Imaging Archive for prognosis analysis and radiomic model construction. The selection of optimal features was conducted using the intraclass correlation coefficient, minimum redundancy maximum relevance, and recursive feature elimination algorithms. A radiomic model for IDH1 prediction and radiomic score (RS) were established using a gradient-boosting machine. Associations between IDH1 expression, RS, clinicopathological variables, and overall survival (OS) were determined using univariate and multivariate Cox proportional hazards regression analyses and Kaplan-Meier curves.

RESULTS

IDH1 emerged as a distinct predictive factor in patients with HNSCC (hazard ratio [HR] 1.535, 95% confidence interval [CI]: 1.117-2.11, P = 0.008). The radiomic model, built on eight optimal features, demonstrated area under the curve values of 0.848 and 0.779 in the training and validation sets, respectively, for predicting IDH1 expression levels. Calibration and decision curve analyses validated the model's suitability and clinical utility. RS was significantly associated with OS (HR=2.22, 95% CI: 1.026-4.805, P = 0.043).

CONCLUSION

IDH1 expression is a significant prognostic marker. The developed radiomic model, derived from CECT features, offers a promising approach for diagnosing and prognosticating HNSCC.

PCK1 as a target for cancer therapy: from metabolic reprogramming to immune microenvironment remodeling

Recently, changes in metabolites and metabolism-related enzymes related to tumor cell proliferation, metastasis, drug resistance, and immunosuppression have become a research hotspot, and researchers have attempted to determine the clinical correlation between specific molecular lesions and metabolic phenotypes. Convincing evidence shows that metabolic reprogramming is closely related to the proliferation, invasion, metastasis, and poor prognosis of malignant tumors. Therefore, targeting metabolic reprogramming is a new direction for cancer treatment. However, how molecular alterations in tumors contribute to metabolic diversity and unique targeting dependencies remains unclear. A full understanding of the underlying mechanisms of metabolic reprogramming in cancer may lead to better identification of therapeutic targets and the development of therapeutic strategies. Evidence for the importance of PCK1, a phosphoenolpyruvate carboxykinase 1, in tumorigenesis and development is accumulating. PCK1 can regulate cell proliferation and metastasis by remodeling cell metabolism. Additionally, PCK1 has "nonclassical" nonmetabolic functions, involving the regulation of gene expression, angiogenesis, epigenetic modification, and other processes, and has an impact on cell survival, apoptosis, and other biological activities, as well as the remodeling of the tumor immune microenvironment. Herein, we provide a comprehensive overview of the functions of PCK1 under physiological and pathological conditions and suggest that PCK1 is a potential target for cancer therapy. We also propose a future exploration direction for targeting PCK1 for cancer therapy from a clinical perspective. Finally, in view of the collective data, the results of our discussion suggest the potential clinical application of targeted PCK1 therapy in combination with chemotherapy and immunotherapy for cancer treatment.

Therapeutic implications of the metabolic changes associated with BRAF inhibition in melanoma

Melanoma metabolism can be reprogrammed by activating BRAF mutations. These mutations are present in up to 50% of cutaneous melanomas, with the most common being V600E. BRAF mutations augment glycolysis to promote macromolecular synthesis and proliferation. Prior to the development of targeted anti-BRAF therapies, these mutations were associated with accelerated clinical disease in the metastatic setting. Combination BRAF and MEK inhibition is a first line treatment option for locally advanced or metastatic melanoma harboring targetable BRAF mutations. This therapy shows excellent response rates but these responses are not durable, with almost all patients developing resistance. When BRAF mutated melanoma cells are inhibited with targeted therapies the metabolism of those cells also changes. These cells rely less on glycolysis for energy production, and instead shift to a mitochondrial phenotype with upregulated TCA cycle activity and oxidative phosphorylation. An increased dependence on glutamine utilization is exhibited to support TCA cycle substrates in this metabolic rewiring of BRAF mutated melanoma. Herein we describe the relevant core metabolic pathways modulated by BRAF inhibition. These adaptive pathways represent vulnerabilities that could be targeted to overcome resistance to BRAF inhibitors. This review evaluates current and future therapeutic strategies that target metabolic reprogramming in melanoma cells, particularly in response to BRAF inhibition.

The Interplay between Autophagy and Mitochondria in Cancer

Besides producing cellular energy, mitochondria are crucial in controlling oxidative stress and modulating cellular metabolism, particularly under stressful conditions. A key aspect of this regulatory role involves the recycling process of autophagy, which helps to sustain energy homeostasis. Autophagy, a lysosome-dependent degradation pathway, plays a fundamental role in maintaining cellular homeostasis by degrading damaged organelles and misfolded proteins. In the context of tumor formation, autophagy significantly influences cancer metabolism and chemotherapy resistance, contributing to both tumor suppression and surveillance. This review focuses on the relationship between mitochondria and autophagy, specifically in the context of cancer progression. Investigating the interaction between autophagy and mitochondria reveals new possibilities for cancer treatments and may result in the development of more effective therapies targeting mitochondria, which could have significant implications for cancer treatment. Additionally, this review highlights the increasing understanding of autophagy's role in tumor development, with a focus on modulating mitochondrial function and autophagy in both pre-clinical and clinical cancer research. It also explores the potential for developing more-targeted and personalized therapies by investigating autophagy-related biomarkers.

Dual-targeted NAMPT inhibitors as a progressive strategy for cancer therapy

In mammals, nicotinamide phosphoribosyltransferase (NAMPT) is a crucial enzyme in the nicotinamide adenine dinucleotide (NAD+) synthesis pathway catalyzing the condensation of nicotinamide (NAM) with 5-phosphoribosyl-1-pyrophosphate (PRPP) to produce nicotinamide mononucleotide (NMN). Given the pivotal role of NAD+ in a range of cellular functions, including DNA synthesis, redox reactions, cytokine generation, metabolism, and aging, NAMPT has become a promising target for many diseases, notably cancer. Therefore, various NAMPT inhibitors have been reported and classified as first and second-generation based on their chemical structures and design strategies, dual-targeted being one. However, most NAMPT inhibitors suffer from several limitations, such as dose-dependent toxicity and poor pharmacokinetic properties. Consequently, there is no clinically approved NAMPT inhibitor. Hence, research on discovering more effective and less toxic dual-targeted NAMPT inhibitors with desirable pharmacokinetic properties has drawn attention recently. This review summarizes the previously reported dual-targeted NAMPT inhibitors, focusing on their design strategies and advantages over the single-targeted therapies.

A Ketogenic Diet Sensitizes Pancreatic Cancer to Inhibition of Glutamine Metabolism

Pancreatic cancer is the third leading cause of cancer death in the United States, and while conventional chemotherapy remains the standard treatment, responses are poor. Safe and alternative therapeutic strategies are urgently needed 1 . A ketogenic diet has been shown to have anti-tumor effects across diverse cancer types but will unlikely have a significant effect alone. However, the diet shifts metabolism in tumors to create new vulnerabilities that can be targeted (1). Modulators of glutamine metabolism have shown promise in pre-clinical models but have failed to have a marked impact against cancer in the clinic. We show that a ketogenic diet increases TCA and glutamine-associated metabolites in murine pancreatic cancer models and under metabolic conditions that simulate a ketogenic diet in vitro. The metabolic shift leads to increased reliance on glutamine-mediated anaplerosis to compensate for low glucose abundance associated with a ketogenic diet. As a result, glutamine metabolism inhibitors, such as DON and CB839 in combination with a ketogenic diet had robust anti-cancer effects. These findings provide rationale to study the use of a ketogenic diet with glutamine targeted therapies in a clinical context.

Advances in pediatric gliomas: from molecular characterization to personalized treatments

Pediatric gliomas, consisting of both pediatric low-grade (pLGG) and high-grade gliomas (pHGG), are the most frequently occurring brain tumors in children. Over the last decade, several milestone advancements in treatments have been achieved as a result of stronger understanding of the molecular biology behind these tumors. This review provides an overview of pLGG and pHGG highlighting their clinical presentation, molecular characteristics, and latest advancements in therapeutic treatments.  Conclusion: The increasing understanding of the molecular biology characterizing pediatric low and high grade gliomas has revolutionized treatment options for these patients, especially in pLGG. The implementation of next generation sequencing techniques for these tumors is crucial in obtaining less toxic and more efficacious treatments. What is Known: • Pediatric Gliomas are the most common brain tumour in children. They are responsible for significant morbidity and mortality in this population. What is New: • Over the last two decades, there has been a significant increase in our global understanding of the molecular background of pediatric low and high grade gliomas. • The implementation of next generation sequencing techniques for these tumors is crucial in obtaining less toxic and more efficacious treatments, with the ultimate goal of improving both the survival and the quality of life of these patients.

Comprehensive Immunogenomic Profiling of IDH1-/2-Altered Cholangiocarcinoma

PURPOSE

Isocitrate dehydrogenase (IDH)1/2 genomic alterations (GA) occur in 20% of intrahepatic cholangiocarcinoma (iCCA); however, the immunogenomic landscape of IDH1-/2-mutated iCCA is largely unknown.

METHODS

Comprehensive genomic profiling (CGP) was performed on 3,067 cases of advanced iCCA. Tumor mutational burden (TMB), PD-L1 expression (Dako 22C3), microsatellite instability (MSI), and genomic loss of heterozygosity (gLOH) as a surrogate marker for homologous recombination deficiency were examined. RNA sequencing of 73 patient samples was analyzed for differences in stromal/immune cell infiltration, immune marker expression, and T-cell inflammation. Tissue microarray arrays were subjected to multiplex immunohistochemistry and colocalization analysis in 100 surgical samples. Retrospective clinical data were collected for 501 patients with cholangiocarcinoma to examine median overall survival (mOS) in IDH1/2+ versus IDHwt.

RESULTS

Of 3,067 iCCA cases subjected to CGP, 426 (14%) were IDH1+ and 125 (4%) were IDH2+. IDH1 GA included R132C (69%) and R132L/G/S/H/F (16%/7%/4%/3%/<1%). IDH2 GA occurred at R172 (94.4%) and R140 (6.6%). No significant difference was seen in median gLOH between IDH1+ versus IDHwt iCCA (P = .37), although patterns of comutations differed. MSI-High (P = .009), TMB ≥10 mut/Mb (P < .0001), and PD-L1 positivity were lower in IDH1/2+ versus IDHwt iCCA. Resting natural killer cell population, CD70, and programmed cell death 1 expression were significantly higher in non-IDH1-mutated cases, whereas V-set domain containing T-cell activation inhibitor 1 (B7-H4) expression was significantly higher in IDH1+. No significant difference in mOS was observed between IDH1/2+ versus IDHwt patients.

CONCLUSION

Significant differences in GA and immune biomarkers are noted between IDH1/2+ and IDHwt iCCA. IDH1-/2-mutated tumors appear immunologically cold without gLOH. These immunogenomic data provide insight for precision targeting of iCCA with IDH alterations.

Chondrosarcoma With Pulmonary Metastatic Calcifications: A Case Report and Review of the Literature

A chondrosarcoma with pulmonary metastatic calcifications is a rarely reported phenomenon. This report discusses chondrosarcomas and their clinical features, diagnosis, and treatment, using as an example the case of a 55-year-old female with a right pelvic chondrosarcoma that developed over 10 years. In the last two years, the patient had increasing pulmonary findings, including pulmonary nodules, ground glass opacities, and likely pulmonary metastatic calcifications. The objective of this report is to explore chondrosarcomas and their pattern of metastatic presentation, with the hope of improving recognition of the disease and streamlining treatment.

Glutamine addiction and therapeutic strategies in pancreatic cancer

Pancreatic cancer remains one of the most lethal diseases worldwide owing to its late diagnosis, early metastasis, and poor prognosis. Because current therapeutic options are limited, there is an urgent need to investigate novel targeted treatment strategies. Pancreatic cancer faces significant metabolic challenges, principally hypoxia and nutrient deprivation, due to specific microenvironmental constraints, including an extensive desmoplastic stromal reaction. Pancreatic cancer cells have been shown to rewire their metabolism and energy production networks to support rapid survival and proliferation. Increased glucose uptake and glycolytic pathway activity during this process have been extensively described. However, growing evidence suggests that pancreatic cancer cells are glutamine addicted. As a nitrogen source, glutamine directly (or indirectly via glutamate conversion) contributes to many anabolic processes in pancreatic cancer, including amino acids, nucleobases, and hexosamine biosynthesis. It also plays an important role in redox homeostasis, and when converted to α-ketoglutarate, glutamine serves as an energy and anaplerotic carbon source, replenishing the tricarboxylic acid cycle intermediates. The present study aims to provide a comprehensive overview of glutamine metabolic reprogramming in pancreatic cancer, focusing on potential therapeutic approaches targeting glutamine metabolism in pancreatic cancer.

Isocitrate Dehydrogenase 1 Mutation and Ivosidenib in Patients With Acute Myeloid Leukemia: A Comprehensive Review

Acute myeloid leukemia (AML) arises from immature myeloid progenitors, resulting in a stem-cell-like proliferative state. This leads to excessive pools of immature cells that cannot function, which usually happens at the cost of the production of mature functional cells, leading to deleterious consequences. The management of AML has intensified as newer targeted therapies have come into existence owing to deeper genetic analysis of the disease and patients. Isocitrate dehydrogenase (IDH) is a cytosolic enzyme that is a part of the Krebs cycle and is extremely important in maintaining the homeostasis of the cell. It is produced by two different genes: IDH1 and IDH2. Ivosidenib has been associated with IDH1 inhibition and has been studied in numerous cancers. This review highlights the studies that have dealt with ivosidenib, an IDH1 inhibitor, in AML, the side effect profile, and the possible future course of the drug. After a scoping review of the available literature, we have identified that studies have consistently shown positive outcomes and that ivosidenib is a promising avenue for the management of AML. But it also has to be kept in mind that resistance to IDH inhibitors is on the rise, and the need to identify ways to circumvent this is to be addressed.

Hsa_circRNA_0084043 promoting tumorigenesis in glioma through miR-577 sponging

Circular RNAs (circRNAs) are important non-coding RNAs (ncRNAs) involved in the development of multiple human diseases, especially cancers. circRNA_0084043 is significantly involved in the progression of melanoma. However, whether circRNA_0084043 is associated with glioma remains unknown. In this study, the upregulation of circRNA_0084043 in glioma and the association between circRNA_0084043 and glioma grade were identified. Our results showed that circRNA_0084043 is significantly involved in the proliferative, migratory, and invasive capacities of glioma cells. The results obtained from starBase, luciferase reporter assays, RNA immunoprecipitation assays, and RNA pull-down assays demonstrated that circRNA_0084043 acts as a direct sponge for miR-577. TargetScan algorithm was used to identify potential miR-577 targets, it was found that sorting nexin 5 (SNX5) is a candidate bound to miR-577. Finally, cell experiments testified that circRNA_0084043 enhanced growth, migration and invasion of glioma through the regulation of miR-577-mediated SNX5. Taken together, we concluded that circRNA_0084043 in the miR-577/SNX5 axis can be used as a candidate target for glioma therapy.

Emerging therapies in cancer metabolism

Metabolic reprogramming in cancer is not only a biological hallmark but also reveals treatment vulnerabilities. Numerous metabolic molecules have shown promise as treatment targets to impede tumor progression in preclinical studies, with some advancing to clinical trials. However, the intricacy and adaptability of metabolic networks hinder the effectiveness of metabolic therapies. This review summarizes the metabolic targets for cancer treatment and provides an overview of the current status of clinical trials targeting cancer metabolism. Additionally, we decipher crucial factors that limit the efficacy of metabolism-based therapies and propose future directions. With advances in integrating multi-omics, single-cell, and spatial technologies, as well as the ability to track metabolic adaptation more precisely and dynamically, clinicians can personalize metabolic therapies for improved cancer treatment.

Targeting wild-type IDH1 enhances chemosensitivity in pancreatic cancer

Pancreatic cancer (PC) is one of the most aggressive types of cancer, with a five-year overall survival rate of 11% among all-comers. Current systemic therapeutic options are limited to cytotoxic chemotherapies which have limited clinical efficacy and are often associated with development of drug resistance. Analysis of The Cancer Genome Atlas showed that wild-type isocitrate dehydrogenase (wtIDH1) is overexpressed in pancreatic tumors. In this study, we focus on the potential roles of wtIDH1 in pancreatic cancer chemoresistance. We found that treatment of pancreatic cancer cells with chemotherapy induced expression of wtIDH1, and this serves as a key resistance factor. The enzyme is protective to cancer cells under chemotherapy-induced oxidative stress by producing NADPH and alpha-ketoglutarate to maintain redox balance and mitochondrial function. An FDA-approved mutant IDH1 inhibitor, ivosidenib (AG-120), is actually a potent wtDH1 inhibitor under a nutrient-deprived microenvironment, reflective of the pancreatic cancer microenvironment. Suppression of wtIDH1 impairs redox balance, results in increased ROS levels, and enhances chemotherapy induced apoptosis in pancreatic cancer vis ROS damage in vitro. In vivo experiments further revealed that inhibiting wtIDH1 enhances chemotherapy anti-tumor effects in patient-derived xenografts and murine models of pancreatic cancer. Pharmacologic wtIDH1 inhibition with ivosidenib represents an attractive option for combination therapies with cytotoxic chemotherapy for patients with pancreatic cancer. Based on these data, we have initiated phase Ib trial combining ivosidenib and multi-agent chemotherapy in patients with pancreatic cancer (NCT05209074).

Metabolic reprograming of cancer as a therapeutic target

Our understanding of metabolic reprogramming in cancer has tremendously improved along with the technical progression of metabolomic analysis. Metabolic changes in cancer cells proved much more complicated than the classical Warburg effect. Previous studies have approached metabolic changes as therapeutic and/or chemopreventive targets. Recently, several clinical trials have reported anti-cancer agents associated with metabolism. However, whether cancer cells are dependent on metabolic reprogramming or favor suitable conditions remains nebulous. Both scenarios are possibly intertwined. Identification of downstream molecules and the understanding of mechanisms underlying reprogrammed metabolism can improve the effectiveness of cancer therapy. Here, we review several examples of the metabolic reprogramming of cancer cells and the therapies targeting the metabolism-related molecules as well as discuss practical approaches to improve the next generation of cancer therapies focused on the metabolic reprogramming of cancer.

Proteomics separates adult-type diffuse high-grade gliomas in metabolic subgroups independent of 1p/19q codeletion and across IDH mutational status

High-grade adult-type diffuse gliomas are malignant neuroepithelial tumors with poor survival rates in combined chemoradiotherapy. The current WHO classification is based on IDH1/2 mutational and 1p/19q codeletion status. Glioma proteome alterations remain undercharacterized despite their promise for a better molecular patient stratification and therapeutic target identification. Here, we use mass spectrometry to characterize 42 formalin-fixed, paraffin-embedded (FFPE) samples from IDH-wild-type (IDHwt) gliomas, IDH-mutant (IDHmut) gliomas with and without 1p/19q codeletion, and non-neoplastic controls. Based on more than 5,500 quantified proteins and 5,000 phosphosites, gliomas separate by IDH1/2 mutational status but not by 1p/19q status. Instead, IDHmut gliomas split into two proteomic subtypes with widespread perturbations, including aerobic/anaerobic energy metabolism. Validations with three independent glioma proteome datasets confirm these subgroups and link the IDHmut subtypes to the established proneural and classic/mesenchymal subtypes in IDHwt glioma. This demonstrates common phenotypic subtypes across the IDH status with potential therapeutic implications for patients with IDHmut gliomas.

Monitoring response to a clinically relevant IDH inhibitor in glioma-Hyperpolarized 13C magnetic resonance spectroscopy approaches

Background

Mutant isocitrate dehydrogenase (IDHmut) catalyzes 2-hydroxyglutarate (2HG) production and is considered a therapeutic target for IDHmut tumors. However, response is mostly associated with inhibition of tumor growth. Response assessment via anatomic imaging is therefore challenging. Our goal was to directly detect IDHmut inhibition using a new hyperpolarized (HP) 13C magnetic resonance spectroscopy-based approach to noninvasively assess α-ketoglutarate (αKG) metabolism to 2HG and glutamate.

Methods

We studied IDHmut-expressing normal human astrocyte (NHAIDH1mut) cells and rats with BT257 tumors, and assessed response to the IDHmut inhibitor BAY-1436032 (n ≥ 4). We developed a new 13C Echo Planar Spectroscopic Imaging sequence with an optimized RF pulse to monitor the fate of HP [1-13C]αKG and [5-12C,1-13C]αKG with a 2.5 × 2.5 × 8 mm3 spatial resolution.

Results

Cell studies confirmed that BAY-1436032-treatment leads to a drop in HP 2HG and an increase in HP glutamate detectable with both HP substrates. Data using HP [5-12C,1-13C]αKG also demonstrated that its conversion to 2HG is detectable without the proximal 1.1% natural abundance [5-13C]αKG signal. In vivo studies showed that glutamate is produced in normal brains but no 2HG is detectable. In tumor-bearing rats, we detected the production of both 2HG and glutamate, and BAY-1436032-treatment led to a drop in 2HG and an increase in glutamate. Using HP [5-12C,1-13C]αKG we detected metabolism with an signal-to-noise ratio of 23 for 2HG and 17 for glutamate.

Conclusions

Our findings point to the clinical potential of HP αKG, which recently received FDA investigational new drug approval for research, for noninvasive localized imaging of IDHmut status.

Most recent update of preclinical and clinical data on radioresistance and radiosensitivity of high-grade gliomas-a radiation oncologist's perspective

PURPOSE

This review article discusses the studies concerning advances in radiotherapy of high-grade gliomas published in the second half of 2021.

METHODS

A literature search was performed in PubMed using the terms ("gliom* and radio*") and time limits 1 July 2021-31 December 2021. The articles were then manually selected for relevance to the analyzed topics.

RESULTS

Considerable progress has been made in the preclinical field on the mechanisms of radioresistance and radiosensitization of high-grade gliomas (HGG). However, fewer early-phase (I/II) clinical trials have been performed and, of the latter, even fewer have produced results that justify moving to phase III. In the 6‑month period under consideration, no studies were published that would lead to a change in clinical practice and the overall survival (OS) of patients remained similar to that of 2005, the year in which it increased significantly for the last time thanks to introduction of the alkylating agent temozolomide.

CONCLUSION

After 17 years of stalemate in improving the OS of patients with HGG, an in-depth analysis of the causes should be carried out in order to identify whether the research efforts conducted so far, including in the radiotherapeutic field, have been the most effective or require improvement. In our opinion, in addition to the therapeutic difficulties related to the biology of HGG tumors (e.g., high infiltrating capacity, multiple resistance mechanisms, blood-brain barrier), some public research policy choices may also play a role, especially in consideration of the limited interest of the pharmaceutical industry in the field of rare cancers.

Wild-type IDH1 inhibition enhances chemotherapy response in melanoma

BACKGROUND

Alternative treatment strategies in melanoma beyond immunotherapy and mutation-targeted therapy are urgently needed. Wild-type isocitrate dehydrogenase 1 (wtIDH1) has recently been implicated as a metabolic dependency in cancer. The enzyme protects cancer cells under metabolic stress, including nutrient limited conditions in the tumor microenvironment. Specifically, IDH1 generates NADPH to maintain redox homeostasis and produces α-ketoglutarate to support mitochondrial function through anaplerosis. Herein, the role of wtIDH1 in melanoma is further explored.

METHODS

The expression of wtIDH1 was determined by qRT-PCR, and Western blot in melanoma cell lines and the effect of wtIDH1 on metabolic reprogramming in melanoma was interrogated by LC-MS. The impact of wtIDH1 inhibition alone and in combination with chemotherapy was determined in cell culture and mouse melanoma models.

RESULTS

Melanoma patients express higher levels of the wtIDH1 enzyme compared to normal skin tissue, and elevated wtIDH1 expression portends poor patient survival. Knockdown of IDH1 by RNA interference inhibited cell proliferation and migration under low nutrient levels. Suppression of IDH1 expression in melanoma also decreased NADPH and glutathione levels, resulting in increased reactive oxygen species. An FDA-approved inhibitor of mutant IDH1, ivosidenib (AG-120), exhibited potent anti-wtIDH1 properties under low magnesium and nutrient levels, reflective of the tumor microenvironment in natura. Thus, similar findings were replicated in murine models of melanoma. In light of the impact of wtIDH1 inhibition on oxidative stress, enzyme blockade was synergistic with conventional anti-melanoma chemotherapy in pre-clinical models.

CONCLUSIONS

These results demonstrate the clinical potential of wtIDH1 inhibition as a novel and readily available combination treatment strategy for patients with advanced and refractory melanoma. Schematic shows increased wild-type IDH1 expression and activity as an adaptive response to metabolic stress induced by chemotherapy.

Emerging role of ferroptosis in glioblastoma: Therapeutic opportunities and challenges

Glioblastoma (GBM) is the most common malignant craniocerebral tumor. The treatment of this cancer is difficult due to its high heterogeneity and immunosuppressive microenvironment. Ferroptosis is a newly found non-apoptotic regulatory cell death process that plays a vital role in a variety of brain diseases, including cerebral hemorrhage, neurodegenerative diseases, and primary or metastatic brain tumors. Recent studies have shown that targeting ferroptosis can be an effective strategy to overcome resistance to tumor therapy and immune escape mechanisms. This suggests that combining ferroptosis-based therapies with other treatments may be an effective strategy to improve the treatment of GBM. Here, we critically reviewed existing studies on the effect of ferroptosis on GBM therapies such as chemotherapy, radiotherapy, immunotherapy, and targeted therapy. In particular, this review discussed the potential of ferroptosis inducers to reverse drug resistance and enhance the sensitivity of conventional cancer therapy in combination with ferroptosis. Finally, we highlighted the therapeutic opportunities and challenges facing the clinical application of ferroptosis-based therapies in GBM. The data generated here provide new insights and directions for future research on the significance of ferroptosis-based therapies in GBM.

Limited nutrient availability in the tumor microenvironment renders pancreatic tumors sensitive to allosteric IDH1 inhibitors

Nutrient-deprived conditions in the tumor microenvironment (TME) restrain cancer cell viability due to increased free radicals and reduced energy production. In pancreatic cancer cells a cytosolic metabolic enzyme, wild-type isocitrate dehydrogenase 1 (wtIDH1), enables adaptation to these conditions. Under nutrient starvation, wtIDH1 oxidizes isocitrate to generate α-ketoglutarate (αKG) for anaplerosis and NADPH to support antioxidant defense. In this study, we show that allosteric inhibitors of mutant IDH1 (mIDH1) are potent wtIDH1 inhibitors under conditions present in the TME. We demonstrate that low magnesium levels facilitate allosteric inhibition of wtIDH1, which is lethal to cancer cells when nutrients are limited. Furthermore, the Food & Drug Administration (FDA)-approved mIDH1 inhibitor ivosidenib (AG-120) dramatically inhibited tumor growth in preclinical models of pancreatic cancer, highlighting this approach as a potential therapeutic strategy against wild-type IDH1 cancers.

Novel Radioiodinated and Radiofluorinated Analogues of FT-2102 for SPECT or PET Imaging of mIDH1 Mutant Tumours

Isocitrate dehydrogenases (IDHs) are metabolic enzymes commonly mutated in human cancers (glioma, acute myeloid leukaemia, chondrosarcoma, and intrahepatic cholangiocarcinoma). These mutated variants of IDH (mIDH) acquire a neomorphic activity, namely, conversion of α-ketoglutarate to the oncometabolite D-2-hydroxyglutarate involved in tumourigenesis. Thus, mIDHs have emerged as highly promising therapeutic targets, and several mIDH specific inhibitors have been developed. However, the evaluation of mIDH status, currently performed by biopsy, is essential for patient stratification and thus treatment and follow-up. We report herein the development of new radioiodinated and radiofluorinated analogues of olutasidenib (FT-2102) as tools for noninvasive single photon emission computed tomography (SPECT) or positron emission tomography (PET) imaging of mIDH1 up- and dysregulation in tumours. Nonradiolabelled derivatives 2 and 3 halogenated at position 6 of the quinolinone scaffold were synthesised and tested in vitro for their inhibitory potencies and selectivities in comparison with the lead compound FT-2102. Using a common organotin precursor, (S)-[¹²⁵I]2 and (S)-[¹⁸F]3 were efficiently synthesised by radio-iododemetallation and copper-mediated radiofluorination, respectively. Both radiotracers were stable at room temperature in saline or DPBS solution and at 37 °C in mouse serum, allowing future planning of their in vitro and in vivo evaluations in glioma and chondrosarcoma models.