Temozolomide Therapy Research Articles

Targeting Retinaldehyde Dehydrogenases to Enhance Temozolomide Therapy in Glioblastoma

Glioblastoma (GB) is an aggressive malignant central nervous system tumor that is currently incurable. One of the main pitfalls of GB treatment is resistance to the chemotherapeutic standard of care, temozolomide (TMZ). The role of aldehyde dehydrogenases (ALDHs) in the glioma stem cell (GSC) subpopulation has been related to chemoresistance. ALDHs take part in processes such as cell proliferation, differentiation, invasiveness or metastasis and have been studied as pharmacological targets in cancer treatment. In the present work, three novel α,β-acetylenic amino thiolester compounds, with demonstrated efficacy as ALDH inhibitors, were tested in vitro on a panel of six human GB cell lines and one murine GB cell line. Firstly, the expression of the ALDH1A isoforms was assessed, and then inhibitors were tested for their cytotoxicity and their ability to inhibit cellular ALDH activity. Drug combination assays with TMZ were performed, as well as an assessment of the cell death mechanism and generation of ROS. A knockout of several ALDH genes was carried out in one of the human GB cell lines, allowing us to discuss their role in cell proliferation, migration capacity and resistance to treatment. Our results strongly suggest that ALDH inhibitors could be an interesting approach in the treatment of GB, with EC50 values in the order of micromolar, decreasing ALDH activity in GB cell lines to 40–50%.

P16.10.A UNRAVELING THE CLINICAL IMPLICATIONS OF TRIM24::NTRK2 FUSION GENE IN PEDIATRIC HIGH-GRADE GLIOMA: A CASE STUDY

Abstract BACKGROUND High-grade gliomas are among the deadliest of all childhood cancers and the leading cause of cancer-related mortality in children. The standard treatment is resection followed by chemotherapy, most often temozolomide and radiation therapy. Unfortunately, there is no evidence that temozolomide influences survival in pediatric patients and only a limited number of new drugs have been identified for specific subgroups of tumors. The identification of fusion genes as possible drivers of the disease offers an opportunity for targeted therapies. We present a case of a six-year-old patient with a novel TRIM24::NTRK2 fusion positive epithelioid glioblastoma with subsequent relapses. METHODS We investigated the ramification of this fusion and evolution of the tumor through whole genome sequencing, RNA-sequencing and DNA methylation profiling, and studied the effect of the patient’s treatment using patient-derived cell cultures. RESULTS Our studies show that the TRIM24::NTRK2 fusion has oncogenic abilities but loses its importance as the tumor evolves. In addition, we demonstrate an increased drug resistance over time, further indicating the diminished driver function of the fusion. CONCLUSION The use of resequencing revealed parallel development of tumor subclones with different genomic alterations, highlighting the importance of genomic profiling from various parts of the tumor. FUNDING This work was supported by the Swedish Research Council, the Swedish Childhood Cancer Foundation, and the Swedish Cancer Society

KINOME-WIDE SYNTHETIC LETHAL SCREEN IDENTIfiES PANK4 AS A MODULATOR OF TEMOZOLOMIDE RESISTANCE IN GLIOBLASTOMA

Abstract AIMS Temozolomide (TMZ) represents the cornerstone of glioblastoma (GBM) therapy. However, acquisition of resistance limits its therapeutic potential. The human kinome is an undisputable source of druggable targets, still, current knowledge remains confined to a limited fraction of it, with a multitude of under-investigated proteins yet to be characterised. We aimed to uncover synthetic lethal partners of TMZ in GBM that could enhance the effect of TMZ, thus improving TMZ therapy response. METHOD A kinome-wide RNAi screen was performed in a TMZ-resistant GBM cell model. A panel of several TMZ-resistant and patient-derived GBM cell lines was implemented for in vitro validation of our findings through several phenotypic assays. In vivo TMZ-resistant GBM xenografts and immunohistochemical (IHC) analysis of IDH- wildtype GBM specimens were employed to assess the clinical relevance of our findings. Tandem Mass Tag (TMT)-based quantitative proteomic studies were undertaken to elucidate the underlying mechanisms. RESULTS Following a kinome-wide RNAi screen, pantothenate kinase 4 (PANK4) was uncovered as a modulator of TMZ resistance in GBM. Validation of PANK4 across various TMZ-resistant GBM cell models, patient-derived GBM cell lines, tissue samples, as well as in vivo studies, corroborated the potential translational significance of these findings. Moreover, PANK4 expression is induced during TMZ treatment, and its expression is associated with a worse clinical outcome. A Tandem Mass Tag (TMT)-based quantitative proteomic approach revealed that PANK4 abrogation leads to a significant downregulation of numerous proteins with central roles in cellular detoxification and cellular response to oxidative stress. Mechanistically, as cells undergo genotoxic stress during TMZ exposure, PANK4 depletion represents a crucial event that can lead to accumulation of intracellular reactive oxygen species (ROS) and subsequent cell death. CONCLUSION Our study provides novel insights into chemoresistance in GBM and unveils a previously unreported role for PANK4 in mediating therapeutic resistance to TMZ in GBM.

Functional germline variants in DNA damage repair pathways are associated with altered survival in adults with glioma treated with temozolomide.

Temozolomide (TMZ) treatment has demonstrated, but variable, impact on glioma prognosis. This study examines associations of survival with DNA repair gene germline polymorphisms among glioma patients who did and did not have TMZ treatment. Identifying genetic markers which sensitize tumor cells to TMZ could personalize therapy and improve outcomes. We evaluated TMZ-related survival associations of pathogenic germline SNPs and genetically predicted transcript levels within 34 DNA repair genes among 1504 glioma patients from the UCSF Adult Glioma Study and Mayo Clinic whose diagnoses spanned pre- and post-TMZ eras within the major known glioma prognostic molecular subtypes. Among those who received TMZ, 5 SNPs were associated with overall survival, but not in those who did not receive TMZ. Only rs2308321-G, in MGMT , was associated with decreased survival (HR=1.21, p=0.019) for all glioma subtypes. Rs73191162-T (near UNG ), rs13076508-C (near PARP3 ), rs7840433-A (near NEIL2 ), and rs3130618-A (near MSH5 ) were only associated with survival and TMZ treatment for certain subtypes, suggesting subtype-specific germline chemo-sensitization. Genetically predicted elevated compared to normal brain expression of PNKP was associated with dramatically worse survival for TMZ-treated patients with IDH -mutant and 1p/19q non-codeleted gliomas (p=0.015). Similarly, NEIL2 and TDG expressions were associated with altered TMZ-related survival only among certain subtypes. Functional germline alterations within DNA repair genes were associated with TMZ sensitivity, measured by overall survival, among adults with glioma, these variants should be evaluated in prospective analyses and functional studies. We observed SNPs associated with glioma survival, specific to cases receiving TMZ An MGMT variant may reduce glioma survival indirectly through myelosuppression Decreased genetic PNKP expression in the brain may sensitize cells to TMZ. The introduction of temozolomide (TMZ) as a part of standard-of-care in the treatment of gliomas marked the last notable increase in patient survival. However, the effectiveness of TMZ is not universal, and can result in serious complications. The mechanism of action behind the drug is the introduction of damaging methyl groups across the tumor genome and leveraging of DNA damage repair (DDR) mechanisms to signal programmed cell death. Previous literature has identified that defects in DDR mechanisms can alter TMZ sensitivity. Using a unique dataset that spans the pre- and post-TMZ eras, we demonstrate that germline variation in DDR-related genes may have significant impact on overall survival for patients treated with TMZ, with no effects observed in the pre-TMZ era. This suggests that germline variants in these DDR genes could be used to personalize TMZ therapy to improve patient survival.

Temozolomide Therapy in Management of Refractory Pituitary Adenomas: A Case Series of 39 Patients

The management of refractory pituitary adenomas (RPA) presents significant challenges. This study aimed to evaluate the long-term treatment outcomes of patients with RPA managed with temozolomide (TMZ) and to identify potential biomarkers for predicting TMZ treatment response. This retrospective case series included patients with RPA who underwent transsphenoidal surgery (TSS) or craniotomy at a comprehensive medical center in China between January 2014 and December 2021. Thirty-nine patients with RPA (median age 42 years; 23 males (59%)) were treated with TMZ for a median of 9 cycles. The median follow-up was 34.4 months. Complete response (CR) was observed in 2 patients, partial response (PR) in 11 patients, stable disease (SD) in 9, progressive disease (PD) in 11, and death in 6 patients. MGMT (O6-methylguanine DNA methyltransferase) levels were significantly lower in patients with CR, PR, or SD compared to those with PD or mortality, with mean values of 24.2% and 58.1, respectively. MSH6 (MutS homologs 6) levels were significantly higher in patients with CR, PR, or SD compared to those with PD or mortality, with mean values of 64.2% and 36.9%, respectively. Patients who received concomitant TMZ and external beam radiotherapy showed a significant tumor size reduction of 178,837mm3 (p<0.001) compared to those treated with TMZ alone. TMZ demonstrates promising efficacy in eliciting tumor responses in patients with PRA. MGMT and MSH6 have emerged as potential biomarkers for predicting treatment response. Furthermore, radiation with concurrent TMZ may significantly improve outcomes in patients with RPA.

The Role of Systemic Therapies in the Treatment of Grades 1-4 Gliomas.

The primary treatment for gliomas typically involves tumor resection followed by adjuvant radiotherapy, with increasing emphasis on chemotherapy and molecularly targeted drugs. This study aimed to review and summarize the literature on the systemic therapy of malignant gliomas.Chemotherapy may be considered in grades 2 and 3 gliomas, especially when mutations in 1p19q-codeletion are detected. The beneficial impact of adding chemotherapy to radiotherapy (PCV: procarbazine, lomustine, vincristine) has also been demonstrated. In grade 4 glioblastoma multiforme (GBM), wild-type isocitrate dehydrogenase (IDH) status showed the best treatment outcomes with temozolomide (TMZ) in patients with O-6-methylguanine-DNA methyltransferase (MGMT)promoter methylation. Prolonging adjuvant TMZ therapy improves treatment outcomes compared to the standard 6-cycle adjuvant therapy. Bevacizumab (BEV) monotherapy can improve progression-free survival and maintain the initial quality of life. Despite advancements in GBM treatment, outcomes remain unsatisfactory, with a median survival of 14-16 months. Further research is still needed regarding the systemic treatment of central nervous system gliomas.

Implementing a Standardized Educational Tool for Patients With Brain Tumors Undergoing Concurrent Temozolomide and Radiation Therapy.

Patients diagnosed with glioblastoma multiforme (GBM) often undergo concurrent temozolomide and radiation therapy. Antineoplastic medication nonadherence continues to be an issue for patients with cancer. This quality improvement project aimed to institute an evidence-based standardized educational tool for patients with GBM undergoing concurrent temozolomide and radiation therapy. To assess medication adherence, patients completed the Brief Adherence Rating Scale at the end of the last radiation therapy visit. Patients and providers completed satisfaction surveys. Data analysis from the administered Brief Adherence Rating Scale demonstrated a mean of 99.3% (N = 13) medication adherence among participants. Median medication adherence was demonstrated to be 100%, with scores ranging from 93% to 100%.

Gastrodin Liposomes Block Crosstalk between Astrocytes and Glioma Cells via Downregulating Cx43 to Improve Antiglioblastoma Efficacy of Temozolomide.

The crosstalk between glioma cells and astrocytes plays a crucial role in developing temozolomide (TMZ) resistance of glioblastomas, together with the existence of the BBB contributing to the unsatisfactory clinical treatment of glioblastomas. Herein, we developed a borneol-modified and gastrodin-loaded liposome (Bo-Gas-LP), with the intent of enhancing the efficacy of TMZ therapy after intranasal administration. The results showed that Bo-Gas-LP improved GL261 cells' sensitivity to TMZ and prolonged survival of GL261-bearing mice by blocking the crosstalk between astrocytes and glioblastoma cells with the decrease of Cx43. Our study showed that intranasal Bo-Gas-LP targeting the crosstalk in glioblastoma microenvironments proposed a promising targeted therapy idea to overcome the current therapeutic limitations of TMZ-resistant glioblastomas.

Integrative single-cell and bulk transcriptome analyses identify a distinct pro-tumor macrophage signature that has a major prognostic impact on glioblastomas

Glioblastoma (GBM) is a highly heterogeneous disease with poor clinical outcomes. To comprehensively dissect the molecular landscape of GBM and heterogeneous macrophage clusters in the progression of GBM, this study integrates single-cell and bulk transcriptome data to recognize a distinct pro-tumor macrophage cluster significantly associated with the prognosis of GBM and develop a GBM prognostic signature to facilitate prior subtypes. Leveraging glioma single-cell sequencing data, we identified a novel pro-tumor macrophage subgroup, marked by S100A9, which might interact with endothelial cells to facilitate tumor progression via angiogenesis. To further benefit clinical application, a prognostic signature was established with the genes associated with pro-tumor macrophages. Patients classified within the high-risk group characterized with enrichment in functions related to tumor progression, including epithelial-mesenchymal transition and hypoxia, displays elevated mutations in the TERT promoter region, reduced methylation in the MGMT promoter region, poorer prognoses, and diminished responses to temozolomide therapy, thus effectively discriminating between the prognostic outcomes of GBM patients. Our research sheds light on the intricate microenvironment of gliomas and identifies potential molecular targets for the development of novel therapeutic approaches.

Neuroradiological, genetic and clinical characteristics of histone H3 K27-mutant diffuse midline gliomas in the Kansai Molecular Diagnosis Network for CNS Tumors (Kansai Network): multicenter retrospective cohort

This study aims to elucidate the clinical and molecular characteristics, treatment outcomes and prognostic factors of patients with histone H3 K27-mutant diffuse midline glioma. We retrospectively analyzed 93 patients with diffuse midline glioma (47 thalamus, 24 brainstem, 12 spinal cord and 10 other midline locations) treated at 24 affiliated hospitals in the Kansai Molecular Diagnosis Network for CNS Tumors. Considering the term “midline” areas, which had been confused in previous reports, we classified four midline locations based on previous reports and anatomical findings. Clinical and molecular characteristics of the study cohort included: age 4–78 years, female sex (41%), lower-grade histology (56%), preoperative Karnofsky performance status (KPS) scores ≥ 80 (49%), resection (36%), adjuvant radiation plus chemotherapy (83%), temozolomide therapy (76%), bevacizumab therapy (42%), HIST1H3B p.K27M mutation (2%), TERT promoter mutation (3%), MGMT promoter methylation (9%), BRAF p.V600E mutation (1%), FGFR1 mutation (14%) and EGFR mutation (3%). Median progression-free and overall survival time was 9.9 ± 1.0 (7.9–11.9, 95% CI) and 16.6 ± 1.4 (13.9–19.3, 95% CI) months, respectively. Female sex, preoperative KPS score ≥ 80, adjuvant radiation + temozolomide and radiation ≥ 50 Gy were associated with favorable prognosis. Female sex and preoperative KPS score ≥ 80 were identified as independent good prognostic factors. This study demonstrated the current state of clinical practice for patients with diffuse midline glioma and molecular analyses of diffuse midline glioma in real-world settings. Further investigation in a larger population would contribute to better understanding of the pathology of diffuse midline glioma.

Pharmacological Modulation of the Cytosolic Oscillator Affects Glioblastoma Cell Biology

The circadian system is a conserved time-keeping machinery that regulates a wide range of processes such as sleep/wake, feeding/fasting, and activity/rest cycles to coordinate behavior and physiology. Circadian disruption can be a contributing factor in the development of metabolic diseases, inflammatory disorders, and higher risk of cancer. Glioblastoma (GBM) is a highly aggressive grade 4 brain tumor that is resistant to conventional therapies and has a poor prognosis after diagnosis, with a median survival of only 12–15 months. GBM cells kept in culture were shown to contain a functional circadian oscillator. In seeking more efficient therapies with lower side effects, we evaluated the pharmacological modulation of the circadian clock by targeting the cytosolic kinases glycogen synthase kinase-3 (GSK-3) and casein kinase 1 ε/δ (CK1ε/δ) with specific inhibitors (CHIR99021 and PF670462, respectively), the cryptochrome protein stabilizer (KL001), or circadian disruption after Per2 knockdown expression in GBM-derived cells. CHIR99021-treated cells had a significant effect on cell viability, clock protein expression, migration, and cell cycle distribution. Moreover, cultures exhibited higher levels of reactive oxygen species and alterations in lipid droplet content after GSK-3 inhibition compared to control cells. The combined treatment of CHIR99021 with temozolomide was found to improve the effect on cell viability compared to temozolomide therapy alone. Per2 disruption affected both GBM migration and cell cycle progression. Overall, our results suggest that pharmacological modulation or molecular clock disruption severely affects GBM cell biology.

Amino-acid PET as a prognostic tool after post Stupp protocol temozolomide therapy in high-grade glioma patients

PurposeThis study aimed to evaluate the prognostic performance of amino-acid PET in high-grade gliomas (HGG) patients at the time of temozolomide (TMZ) treatment discontinuation, after the Stupp protocol.MethodsThe analysis included consecutive HGG patients with dynamic [18F]FDOPA PET imaging within 3 months of the end of TMZ therapy, post-Stupp protocol. Static and dynamic PET parameters, responses to RANO criteria for MRI and clinical and histo-molecular factors were correlated to progression-free (PFS).ResultsThirty-two patients (59.4 [54.0;67.6] years old, 13 (41%) women) were included. Static PET parameters peak tumor-to-background ratio and metabolic tumor volume (respective thresholds of 1.9 and 1.5 mL) showed the best 84% accuracies for predicting PFS at 6 months (p = 0.02). These static PET parameters were also independent predictor of PFS in multivariate analysis (p ≤ 0.05).ConclusionIn HGG patients having undergone a Stupp protocol, the absence of significant PET uptake after TMZ constitutes a favorable prognostic factor.

A simple and rapid in vitro assay foridentification of direct inhibitors of O6-methylguanine-DNA methyltransferase.

O6-Methylguanine-DNA methyltransferase (MGMT) is a DNA repair enzyme that is overexpressed in certain tumors and is associated with resistance to the DNA alkylating agent temozolomide. MGMT inhibitors show potential in combating temozolomide resistance, but current assays for MGMT enzyme activity and inhibition, primarily oligonucleotide-based and fluorescent probe-based, are laborious and costly. The clinical relevance of temozolomide therapy calls for more convenient methodologies to study MGMT inhibition. Here, we extended the application of SNAP-Capture magnetic beads to develop a novel MGMT inhibition assay that demonstrated efficacy not only with known MGMT inhibitors, but also with the aldehyde dehydrogenase inhibitor, disulfiram. The assay uses standard fluorescence microscopy as a simple and reliable detection method, and is translationally applicable in drug discovery programs.

Extraction of Unstructured Electronic Health Records to Evaluate Glioblastoma Treatment Patterns.

Data on lines of therapy (LOTs) for cancer treatment are important for clinical oncology research, but LOTs are not explicitly recorded in electronic health records (EHRs). We present an efficient approach for clinical data abstraction and a flexible algorithm to derive LOTs from EHR-based medication data on patients with glioblastoma multiforme (GBM). Nonclinicians were trained to abstract the diagnosis of GBM from EHRs, and their accuracy was compared with abstraction performed by clinicians. The resulting data were used to build a cohort of patients with confirmed GBM diagnosis. An algorithm was developed to derive LOTs using structured medication data, accounting for the addition and discontinuation of therapies and drug class. Descriptive statistics were calculated and time-to-next-treatment (TTNT) analysis was performed using the Kaplan-Meier method. Treating clinicians as the gold standard, nonclinicians abstracted GBM diagnosis with a sensitivity of 0.98, specificity 1.00, positive predictive value 1.00, and negative predictive value 0.90, suggesting that nonclinician abstraction of GBM diagnosis was comparable with clinician abstraction. Of 693 patients with a confirmed diagnosis of GBM, 246 patients contained structured information about the types of medications received. Of them, 165 (67.1%) received a first-line therapy (1L) of temozolomide, and the median TTNT from the start of 1L was 179 days. We described a workflow for extracting diagnosis of GBM and LOT from EHR data that combines nonclinician abstraction with algorithmic processing, demonstrating comparable accuracy with clinician abstraction and highlighting the potential for scalable and efficient EHR-based oncology research.

T-antigen as a biomarker of progression-free survival in patients with glioblastoma.

Glioblastoma (GBM) is one of the most aggressive brain tumors and often leads to poor outcomes. Studies have indicated that glycan levels are significantly correlated with the pathogenesis and development of cancers. However, whether glycan levels can serve as diagnostic or prognostic biomarkers in GBM remains unclear. We obtained glycomic profiles in tissue and serum samples from 55 individuals with GBM using a well-established lectin biochip platform probing with 11 specific lectins. Our univariate analysis showed that 5 out of the 11 lectin-probed glycans (LPGs) were significantly higher in GBM tissues than in peri-tumoral tissues. After logistic regression analyses, only the Jacalin-probed T-antigen difference between the two groups remained significant (p = 0.037). Moreover, survival-related analyses showed that the level of Jacalin-probed T-antigen was significantly associated with the progression-free survival (p = 0.038) of patients. However, none of the LPG levels were correlated with the overall survival or the chemosensitivity to temozolomide therapy. The correlation coefficient analysis showed a moderate-to-strong correlation in the Jacalin-probed T-antigen levels between GBM tissues and serum samples, indicating its potential usefulness as a non-invasive GBM progression biomarker. Glycomics analyses can be helpful in the prediction of GBM recurrences and may provide information useful for GBM glycan-based target therapies or vaccine development.

Temozolomide therapy in an aggressive ACTH-producing pituitary tumour

Temozolomide therapy in an aggressive ACTH-producing pituitary tumour

First parechovirus reported case in Saudi Arabia in hospitalized immunocompromised adult patient

Human parechovirus, a member of the Picornaviridae family (PeVs), can lead to severe infections, including severe meningitis, meningoencephalitis, and sepsis-like syndrome. We report a case of human parechovirus-related encephalitis in a 52-year-old woman diagnosed with glioblastoma multiforme. She underwent surgical resection in June 2022. Unfortunately, her disease recurred, and she underwent a second resection in August 2022, followed by radiation therapy and Temozolomide therapy. She presented to the hospital with acute confusion followed by seizures, necessitating intubation for airway support. A cerebrospinal fluid (CSF) sample was obtained and processed using the Biofire FilmArray, which reported the detection of HSV-1. Despite being on Acyclovir, the patient did not show signs of improvement. Consequently, a second CSF sample was obtained and sent for next-generation sequencing (NGS), which returned a positive result for Parechovirus. In this presented case, the patient exhibited symptoms of an unknown infectious cause. The utilization of NGS and metagenomic analysis helped identify Parechovirus as the primary pathogen present, in addition to previously identified HSV. This comprehensive approach facilitated a thorough assessment of the underlying infection and guided targeted treatment. In conclusion, the application of NGS techniques and metagenomic analysis proved instrumental in identifying the root cause of the infection.

Utility of clinical and MR imaging parameters for prediction and monitoring of response to capecitabine and temozolomide (CAPTEM) therapy in patients with liver metastases of neuroendocrine tumors.

This study explores the predictive and monitoring capabilities of clinical and multiparametric MR parameters in assessing capecitabine and temozolomide (CAPTEM) therapy response in patients with neuroendocrine tumors (NET). This retrospective study (n = 44) assessed CAPTEM therapy response in neuroendocrine liver metastases (NELM) patients. Among 33 monitored patients, as a subgroup of the overall study cohort, pretherapeutic and follow-up MRI data (size, apparent diffusion coefficient [ADC] values, and signal intensities), along with clinical parameters (chromogranin A [CgA] and Ki-67%), were analyzed. Progression-free survival (PFS) served as the reference. Responders were defined as those with PFS ≥ 6 months. Most patients were male (75%) and had G2 tumors (76%) with a pancreatic origin (84%). Median PFS was 5.7 months; Overall Survival (OS) was 25 months. Non-responders (NR) had higher Ki-67 in primary tumors (16.5 vs. 10%, p = 0.01) and increased hepatic burden (20% vs. 5%, p = 0.007). NR showed elevated CgA post-treatment, while responders (R) exhibited a mild decrease. ADC changes differed significantly between groups, with NR having decreased ADCmin (-23%) and liver-adjusted ADCmean/ADCmean liver (-16%), compared to R's increases of ADCmin (50%) and ADCmean/ADCmean liver (30%). Receiver operating characteristic (ROC) analysis identified the highest area under the curve (AUC) (0.76) for a single parameter for ∆ ADC mean/liver ADCmean, with a cut-off of < 6.9 (76% sensitivity, 75% specificity). Combining ∆ Size NELM and ∆ ADCmin achieved the best balance (88% sensitivity, 60% specificity) outperforming ∆ Size NELM alone (69% sensitivity, 65% specificity). Kaplan-Meier analysis indicated significantly longer PFS for ∆ ADCmean/ADCmean liver < 6.9 (p = 0.024) and ∆ Size NELM > 0% + ∆ ADCmin < -2.9% (p = 0.021). Survival analysis emphasizes the need for adapted response criteria, involving combined evaluation of CgA, ADC values, and tumor size for monitoring CAPTEM response in hepatic metastasized NETs.

Abstract CT201: Phase 2 clinical trial of OKN-007 in recurrent malignant glioma

Abstract Background: OKN-007 is a novel nitrone anti-cancer agent. OKN-007 plus Temozolomide (TMZ) increased survival in glioma-bearing mice compared to TMZ alone. Furthermore, OKN-007 increased TMZ sensitivity in both TMZ-sensitive and TMZ-resistant cell lines. Following a phase I study in recurrent glioblastoma (rGBM), we initiated a phase 2 clinical trial (NCT04388475) of OKN-007 combined with TMZ to examine the efficacy, safety, and pharmacokinetic properties of OKN-007 combined with TMZ. Here, we report the safety and efficacy findings of this ongoing trial. Methods: This is a multi-center, open label phase 2 clinical trial in first or second rGBM WHO Grade (Gr) IV. Adult patients with rGBM previously treated with standard radiation and chemotherapy (Stupp regimen) were eligible. Any second-line therapy was acceptable, excluding bevacizumab. Patients were treated with OKN-007, administered intravenously, at 60 mg/kg, three times weekly for 12 weeks, then twice weekly for 12 weeks, then once weekly until progression. TMZ was administered orally, at a dose of 150 mg/m2 (Cycle 1) or 200 mg/m2 (subsequent cycles). An initial 3-patient safety lead-In cohort established the safety of the OKN-007 and TMZ combination in this patient population. Kaplan-Meier analysis was used to determine progression-free (PFS) and overall survival (OS). Additionally, a comparative analysis of PFS and OS for a matched external control rGBM population treated with lomustine in other formal randomized clinical trials was performed. Results: 57 patients were enrolled at study completion. Of 57 patients enrolled, there were no adverse events (AEs) deemed as a dose-limiting toxicity in the safety Lead-In cohort with 3 patients. Median age was 56 years (range, 29-82), and 41 patients were treated with one line of prior anti-cancer therapy and 15 were treated with two prior lines. Eighteen patients experienced 46 SAEs and of these 9 (Gr3 nausea, Gr2 vomiting, Gr3 fatigue, Gr2 infusion related reaction, Gr3 acute liver injury, Gr3 generalized weakening upper and lower extremities, Gr3 bilirubin increase, Gr3 AST and ALT increase) were deemed to be possibly related to administration of OKN-007. For 56 patients receiving the combination of OKN-007 and TMZ, median PFS was 2.2 (95% CI, 1.6-3.6) months vs. 1.8 (95% CI, 1.7-1.9) months in control patients. Median OS was 9.7 (95% CI 7.6-12.5) months vs. 7.2 (95% CI, 6.8-7.8) months (Cox hazard ratio (HR) = 0.68, p = 0.034). 6-month PFS rate was 23.6% (95% CI, 13.5-35.4) vs. 13.0% (95% CI, 10.0-16.4) and 12-month OS rate was 38.1% (95% CI, 25.1-50.9) vs. 26.3% (95% CI, 22.0-30.8), respectively. Conclusions: Our data indicate that the combination therapy of OKN-007 and TMZ appears safe and, compared to standard lomustine therapy, may prolong OS in rGBM. Citation Format: James Battiste, Glenn Lesser, Santosh Kesari, Varun Monga, Tobias Walbert, Kaylyn Sinicrope, Burt Nabors, Jason Schroeder, Eric Wong, Barry D. Anderson, Hyun Sook Kim, Shinwook Kang. Phase 2 clinical trial of OKN-007 in recurrent malignant glioma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr CT201.

Abstract 1441: Establishing a novel clinically relevant disease model of glioblastoma

Abstract Introduction: GBM is the most common primary malignancy of the CNS. Historically pre-clinical models have failed to predict response in humans, despite promising preclinical data. Moreover, current models seldom incorporate surgical resection and/or standard of care chemotherapy treatment. These models also commonly employ young animals exclusively, whose immune contexture differs from older patients. We therefore sought to establish an improved, orthotopic, preclinical GBM model, which better recapitulates patient response to standard-of-care and targeted treatments. Methods: NFpp10a-Luc2 GBM cells were orthotopically implanted into C57BL/6-mice (aged[&amp;gt;18months] and young[6-8weeks]) and weekly bioluminescence imaging performed to monitor tumor growth. Overall survival (OS) and tumor growth were assessed in response to (1) Surgical Resection, (2) Temozolomide (TMZ) (3) anti-PD1 (4) neoadjuvant anti-PD1 and (5) Regorafenib (REGO) therapy. Tissue collected post-mortem underwent bulk RNA sequencing followed by analysis via microenvironment cell population counter (MCP) and gene set enrichment (GSEA) to determine changes in the GBM-TME following treatment. Results: We demonstrated OS advantage in aged mice undergoing surgical resection (Resection:33.5 days vs Non-Resection: 18 days; p=0.0166) and observed age to be a significant prognostic factor (Young:62 days vs Aged: 22 days; p=0.0002). Subsequently, we observed that TMZ and anti-PD1 monotherapies had no impact on NFpp10-Luc2 growth (p=0.9001, p=0.7933) or survival (p=0.3035, p=0.6328). Neoadjuvant anti-PD1 treated mice demonstrated no significant survival advantage compared to IgG control (33 days vs 35 days; p=0.9429). Lastly, REGO treatment demonstrated a trend towards improved OS vs Vehicle (p=0.096). MCP analysis revealed both neoadjuvant anti-PD1 and REGO treatment induced influx of CD8+ T cells, B cells and monocytes into the TME, with neoadjuvant anti-PD1 associated with an upregulation of CXCR3 (p=0.0045). Conclusions: We have, for the first time, established and characterized response of the NFpp10a-C57BL/6 model to surgical resection, TMZ, anti-PD1 and REGO therapy in both young and aged mice. We have shown the model is markedly insensitive to intervention with chemotherapy and immune checkpoint therapy, mirroring what is seen clinically in patients. The model may therefore be employed in future pre-clinical studies to guide clinical trials in the setting of mesenchymal GBM. Citation Format: Kate Connor, Kieron White, James Clerkin, Kieron Sweeney, Liam Shiels, Thomas van Brussel, Ingrid Arijs, Diether Lambrechts, Gautam Shankar, Frederik de Smet, Stephen G. Maher, Laure Marignol, Patrick Dicker, Jochen Prehn, David O'Brien, Annette T. Byrne. Establishing a novel clinically relevant disease model of glioblastoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1441.