Lukas, Rimas V.

Abstract Background: Glioblastoma recurrence is inevitable despite aggressive surgical resection of contrast enhancing (CE) tumor. Unlike the deep molecular characterization of CE glioblastoma, unresected infiltrating tumor, representing minimal residual disease (MRD) has not been well profiled. Increasingly, clinical trials are being conducted in the MRD setting for glioblastoma patients, necessitating understanding of unresected infiltrating tumor for targeted therapeutic development. Methods: Visium HD spatial transcriptomics was used to profile a cohort of newly diagnosed, treatment-naïve glioblastoma patients that underwent supramaximal resection, with both core and infiltrating in situ components. Spatial profiles generated expression signatures of infiltrative and CE tumor. For in silico prediction of therapeutics targeting the MRD, expression signatures of infiltrative and CE tumor were compared with drug perturbation signatures from the NIH L1000 database using the sRGES method to predict reversal of disease expression patterns. IC50 data from human cell lines were aggregated from the Genomics of Drug Sensitivity in Cancer or individual study data while blood-brain barrier (BBB) penetrance was predicted using the CNS-MPO approach. Findings: Infiltrative tumor expression profiles were enriched for genes corresponding to neural and oligodendrocyte progenitor like cells. In contrast CE glioblastoma displayed mesenchymal and astrocytic programs, suggesting spatial concentration of glioblastoma states within MRD and CE tumor. For CE glioblastoma, proteasome inhibitors and glucocorticoid receptor agonists were predicted to have the highest antitumor activity. In contrast, histone deacetylase inhibitors (HDACi) were highly ranked for MRD while exhibiting low predicted efficacy in CE tumor. Synergy analysis of drug candidates provided multiple dual treatment options for both the CE and MRD contexts. Conclusions: Cumulatively, these data indicate that the resected tumor does not reflect the MRD state, providing clarity on why targeted therapeutics for glioblastoma have not been particularly successful. Spatial profiling of the MRD demonstrates vulnerability to unique drug targets, which if utilized in the correct setting could confer greater survival benefit. Citation Format: Harrshavasan Congivaram, Shashwat Tripathi, Mateo Gomez, Katy McCortney, Ching Man Wai, Ruochen Du, Thomas K. Sears, Jianzhong Zhang, Daniel J. Brat, Craig M. Horbinski, Mark W. Youngblood, Jared T. Ahrendsen, Adam M. Sonabend, Stephen T. Magill, Matthew C. Tate, Maciej S. Lesniak, Sean Sachdev, Timothy Sita, Priya Kumthekar, Karan Dixit, Robin Buerki, Ditte Primdahl, Mustafa Khasraw, John de Groot, David A. Reardon, Rimas V. Lukas, Roger Stupp, Amy B. Heimberger. In silico screening of therapeutics candidates targeting minimal residual disease in glioblastoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 1 (Regular Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(7 Suppl):Abstract nr 2496.

Abstract BACKGROUND Glioblastoma (GBM) is highly aggressive with poor prognosis, especially in recurrent cases where treatments are limited. Intra-arterial (IA) Yttrium-90 (Y90) microsphere therapy, FDA-approved for hepatocellular carcinoma, offers the potential for targeted radiotherapy in recurrent GBM (rGBM). The FRONTIER trial evaluated the safety and feasibility of IA Y90-glass microsphere treatment for rGBM under an FDA Investigational Device Exemption. Materials and METHODS This prospective, single-arm, multi-center study included patients with rGBM in non-dominant, non-eloquent regions. The primary endpoint was 30-day incidence of treatment-related limiting toxicities (primarily ≥grade 3 non-hematologic, with exclusions). Secondary endpoints included adverse event (AE) rate, neurological changes, technical success (PET absorbed dose within ±20% of target), and efficacy. Treatment regions, defined via cerebral angiography-MRI fusion to cover the recurrent lesion, were targeted with 40±4Gy. Post-treatment evaluations included MRI, Y90-PET, and neurological assessments. RESULTS The procedure was well-tolerated by all twelve subjects and discharge occurred the following day with no decline in neurologic status. No limiting toxicities or device-related AEs were reported. Five patients experienced 8 procedure-related AEs (6 Grade 1, 2 Grade 3). Technical success was 100%, with post-treatment Y90-PET derived median absorbed dose of 41.5 Gy to the treatment region (median volume 80.3 cc). The median tumor absorbed dose was considerably higher at 124.2 Gy (median tumor volume 5.8 cc), indicating preferential tumor perfusion. At 2 months, 67% had stable disease, and 33% showed reduced T1-contrast enhancing volume within the treated area. Median progression-free survival was 3.1 (95% CI 0.92-NE) and overall survival (OS) was 9.3 months (95% CI 5.0-NE) from Y90 treatment. Exploratory analysis revealed a significant OS benefit for patients receiving a tumor absorbed dose above the median (11.9 vs 5.7 months, p=0.0073). CONCLUSION Results from this initial cohort suggest IA Y90-microsphere therapy is technically feasible and well-tolerated in rGBM. Further investigation is warranted.

Abstract AIMS Glioblastoma (GBM) has a poor prognosis, which is compounded by an increase in treatment-related toxicity with age. TTFields are electric fields that exert physical forces to disrupt cellular processes critical for cancer cell viability. Subgroup analysis of the phase 3 EF-14 study demonstrated TTFields therapy to be well-tolerated in patients ≥65 years with newly diagnosed (nd) GBM. We report safety data in elderly patients from a global post- marketing surveillance (PMS) analysis of patients with central nervous system (CNS) malignancies receiving TTFields. METHOD PMS data was collected from patients receiving TTFields (October 2011–March 2022) in North America, Europe, Middle East, Africa, and Japan. Adverse events (AEs) were categorized using MedDRA version 25.1. RESULTS Overall, 25,898 patients were included (diagnoses: ndGBM [68%], recurrent GBM [26%], anaplastic astrocytoma/oligodendroglioma [4%], other [2%]). Of these, 7808 patients (30%) were elderly (>65 years). 75% of elderly patients experienced ≥1 AE, with 57% related to TTFields; comparable frequencies to the overall population (73% and 56%, respectively). The most common treatment-related AE in elderly patients was skin reaction (45%; overall population: 43%). Incidence of treatment-related fall and fracture in elderly patients was 1% and <1%, respectively. Incidence of treatment-related ‘quality-of-life decreased’ was 2% (elderly and overall). No systemic toxicities were reported, regardless of age group. CONCLUSIONS These real-world data demonstrate TTFields has a tolerable safety profile in elderly patients with CNS malignancies, consistent with elderly subgroup data from EF-14, and with no new safety signals. Most AEs were localised, manageable, mild–moderate skin reactions.

Abstract BACKGROUND TTFields are electric fields that exert physical forces to disrupt cellular processes critical for cancer cell viability and tumor progression. TTFields therapy is approved for adults with recurrent (r) and newly diagnosed (nd) glioblastoma (GBM), based on the phase 3 EF-11 (TTFields 200 kHz) and EF-14 studies (TTFields therapy 200 kHz + temozolomide), respectively, which showed clinical benefit without increase in systemic adverse events (AEs). Pediatric patients were not included in the EF-11 and EF-14 studies. Here, we present pediatric safety data from an updated global post-marketing surveillance (PMS) analysis of patients with brain tumors treated with TTFields therapy, over an 11-year timeframe. METHODS Unsolicited PMS data from patients with brain tumors who received TTFields therapy from October 2011-March 2022 in North America, Europe, Middle East, Africa, and Japan were included. AEs were categorized using MedDRA version 25.1. RESULTS Overall, 25,898 patients were included. Diagnoses were ndGBM (68%), rGBM (26%), anaplastic astrocytoma/oligodendroglioma (4%) and other (2%). Two-thirds of patients were male. The analysis included 93 (0.4%) pediatric/adolescent patients (<18 years). In pediatric patients, 62% experienced ≥1 AE, with 53% related to TTFields therapy; these values were comparable with the overall population (73% and 56%, respectively). The most common treatment-related AEs in pediatric patients were: skin reaction (39%), heat sensation (14%), and headache (12%); and in the overall population were: skin reaction (43%), electric sensation (14%), and heat sensation (12%). CONCLUSIONS This long-term, global, real-world data analysis, including pediatric patients with brain tumors, demonstrates a tolerable safety profile of TTFields therapy, consistent with pivotal clinical studies. There were no major differences in AEs between pediatric and adult patients and no new safety signals identified in the pediatric population. Consistent with the overall dataset, most AEs in pediatric patients were localized mild–moderate skin events, which are typically easily managed.

2049 Background: Glioblastoma (GBM) has a poor prognosis. Standard treatments are associated with systemic toxicity, further increasing the disease burden in this patient population. Tumor Treating Fields (TTFields) are electric fields that disrupt cancer cell processes which affect cancer cell viability, and are generated by a portable, wearable device which is locoregional and noninvasive. TTFields therapy was approved by the FDA for the treatment of newly diagnosed (nd) and recurrent (r) GBM based on the phase 3 EF-14 (TTFields therapy 200 kHz + temozolomide) and EF-11 (TTFields 200 kHz) studies, respectively. TTFields therapy is also approved for pleural mesothelioma. We report an updated global, post-marketing surveillance (PMS) safety analysis of patients with CNS malignancies treated with TTFields therapy over an 11-year timeframe. This analysis represents the largest dataset of TTFields therapy use to date. Methods: Unsolicited safety data were collected from routine post-marketing activities for patients (N = 25,898) in North America, Europe, Middle East and Africa and Japan, from October 2011 to March 2022. AEs were stratified by diagnosis, age, and sex and categorized using MedDRA version 25.1. Results: Diagnoses were ndGBM (68%), rGBM (26%), anaplastic astrocytoma/oligodendroglioma (4%) and other (2%). Baseline demographics were reflective of real-world practice: median (range) age was 59 (3–103) years; two-thirds of patients were male. Most (69%) patients were 18–65 years; 0.4% were < 18 years, and 30% were > 65 years. All-cause and TTFields-related AEs occurred in 18,798 (73%) and 14,599 (56%), patients, respectively. The most common device-related AE was skin reaction (43% patients overall). There were no major differences in occurrence of this AE between pediatric, adult, and elderly groups (39%, 42%, and 45%, respectively), or between males and females (41% and 46%, respectively). The incidence of device-related skin reactions was higher in ndGBM than rGBM (46% vs 34%, respectively), in line with previous reports. Only 405 (2%) of patients overall reported an AE of treatment-related ‘quality-of-life decreased’. In line with the phase 3 studies, there were no treatment-related systemic AEs. Conclusions: In this updated global PMS safety analysis, TTFields therapy demonstrated a tolerable safety profile in patients with CNS malignancies, with no new safety findings. In line with previous real-world and clinical data, most AEs were localized, non-serious skin events, which were consistent between age groups. Such events can typically be managed easily using prophylaxis and topical therapies, together with optimization of caregiver techniques. Importantly, no TTFields therapy-related systemic AEs were detected.

Abstract Patients with glioblastoma (GBM) face poor outcomes; the 5-year survival rate is 7% with standard of care treatments, which are frequently associated with systemic toxicity. Tumor Treating Fields (TTFields) are electric fields that disrupt critical cancer cell processes. The TTFields therapy device consists of a portable electric field generator and arrays placed on the patient’s scalp, thus delivery is locoregional and noninvasive. Currently, TTFields therapy is approved for recurrent and newly diagnosed GBM, based on the phase 3 EF-11 (TTFields 200 kHz) and EF-14 studies (TTFields therapy 200 kHz + temozolomide), respectively. These studies confirmed that TTFields therapy had a tolerable safety profile with mild-to-moderate localized skin adverse events (AEs) being the most common related AEs. Here, we present an updated analysis of the largest global real-world evidence dataset of patients with brain tumors receiving TTFields therapy over an 11-year time period. Unsolicited safety data were obtained from routine post-marketing activities, including published literature and interactions with patients, caregivers, and healthcare professionals. Safety data were grouped according to age, diagnosis, and sex. AEs were categorized using MedDRA version 25. Data from 25,898 patients were included in this analysis; median age was 59 years (range: 3-103) for patients with known age. Diagnoses were ndGBM (67.7%), rGBM (26.1%), anaplastic astrocytoma/oligodendroglioma (4.2%) and other (2.1%). Most (n=17,817, 68.8%) patients were 18-65 years of age; n=93 (0.4%) were pediatric/adolescent patients (&lt;18 years), and n=7,808 (30.2%) were elderly patients (&gt;65 years). For 130 patients (0.5%) age was not known. Two-thirds of patients were male, which reflects the preponderance of CNS tumors in males. Most patients were based in North America (72.1%), followed by Europe, the Middle East and Africa (23.3%), and Japan (4.6%). Overall, 72.4% of patients experienced at least one AE, with 55.9% being related to TTFields therapy. The most common AEs (overall and related to TTFields therapy) were skin reactions (42.0%), electric (tingling) sensations (13.5%), and heat (warmth) sensations (11.8%). The percentage of patients experiencing ≥1 AE in the pediatric/adolescent, 18-65, and elderly groups was 63.4%, 74.6%, and 68.4%, respectively. The percentage of females and males experiencing ≥1 AE was 75.2% and 70.9%, respectively. These long-term, real-world data from the largest global dataset of patients with brain tumors using TTFields therapy to date demonstrate a tolerable safety profile consistent with pivotal clinical studies. There were no new safety signals, and most AEs were manageable localized mild-moderate skin events that can be resolved. The distribution of AEs between age and sex was similar, with broad applicability among different patient groups. Citation Format: Maciej M. Mrugala, Wenyin Shi, Fabio Iwamoto, Rimas V. Lukas, Joshua D. Palmer, John H. Suh, Martin Glas. Patients with glioblastoma (GBM) treated with tumor treating fields (TTFields) therapy: post-marketing safety data over the last decade [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3221.

AbstractAccurate pathologic diagnoses and molecularly informed treatment decisions for a wide variety of cancers depend on robust clinical molecular testing that uses genomic, epigenomic, and transcriptomic-based tools. Nowhere is this more essential than in the workup of brain tumors, as emphasized by the incorporation of molecular criteria into the 2016 World Health Organization classification of central nervous system tumors and the updated official guidelines of the National Comprehensive Cancer Network. Despite the medical necessity of molecular testing in brain tumors, access to and utilization of molecular diagnostics is still highly variable across institutions, and a lack of reimbursement for such testing remains a significant obstacle. The objectives of this review are (i) to identify barriers to adoption of molecular testing in brain tumors, (ii) to describe the current molecular tools recommended for the clinical evaluation of brain tumors, and (iii) to summarize how molecular data are interpreted to guide clinical care, so as to improve understanding and justification for their coverage in the routine workup of adult and pediatric brain tumor cases.