Ruff, Michael W.

Abstract BACKGROUND The IDH inhibitor vorasidenib was FDA-approved for treatment of IDH-mutant grade 2 gliomas in August 2024. We evaluated vorasidenib in patients with grade 3 and 4 IDH-mutant gliomas who would not have been eligible for the INDIGO trial. METHODS Retrospective review of patients with grade 3 or 4 IDH-mutant gliomas treated with vorasidenib between 9/1/24 and 5/31/25. Prior treatments, radiographic response, adverse events and seizure control were collected for each patient. RESULTS Thirty-two patients (median age 39.5, 46.9% female) met inclusion criteria. Tumor types included grade 3 oligodendroglioma (11, 34.4%), grade 3 astrocytoma (13, 40.6%) and grade 4 astrocytoma (8, 25%). Thirty patients had contrast-enhancement; 2 patients had non-enhancing tumor. Prior treatments included surgical resection (30, 93.8%), radiation (27, 84.4%), cytotoxic chemotherapy (25, 78.1%), bevacizumab (5, 15.6%), pembrolizumab (3, 9.4%), and ivosidenib (8, 25%). Four patients (12.5%) were naïve to systemic treatment at the time of vorasidenib initiation. Median duration of vorasidenib was 101.5 days (range 18-255) with 19 patients still on vorasidenib at the time of last follow-up. Seventeen patients (53.1%) had stable disease, 11 (34.4%) had progressive disease, 2 (6.3%) did not yet have response assessment, and 2 (6.3%) died. Grade 1 transaminitis occurred in 12 patients with no high grade transaminitis. Two patients developed lymphopenia; both were heavily pre-treated with multiple alkylating agents; no other hematologic toxicity was noted. One patient developed myalgias leading to vorasidenib discontinuation. Nine patients had fatigue, 4 headaches, 2 nausea, 2 decreased appetite. In patients with a history of epilepsy, there were no reported seizures. CONCLUSIONS Vorasidenib was well-tolerated in this heavily pre-treated cohort of grade 3–4 IDH-mutant gliomas, with low-grade transaminitis and fatigue being the most common toxicities. Preliminary results show disease stability in 53.1% of patients after a median of 3.5 months. Conclusions are limited by short-interval follow-up.

Abstract Glioblastoma, IDH-wildtype (GBM), and primary central nervous system lymphoma (PCNSL) are two aggressive brain tumors with distinct treatment strategies but overlapping imaging features on MRI. Accurate preoperative differentiation remains a clinical challenge, due to their overlapping imaging features, even when advanced MRI techniques are employed. This study explored deep learning approaches leveraging multi-sequence MRI to distinguish GBM from PCNSL. Models were developed utilizing 146 PCNSL cases, which were matched to146 GBM by age, sex and year of diagnosis. A 3D-DenseNet121 convolutional neural network was trained using two analytical strategies: (i) loss-based model selection and (ii) ensemble prediction using five-fold cross-validation. Model performance was evaluated on an independent validation set of 256 GBM and 37 PCNSL from the same institution as well as 36 PCNSL cases from an external institution. All MRIs were preprocessed using the FeTS pipeline. Using the independent validation cohort, area under the receiver operating characteristic curve (AUC) and 95% confidence intervals (CI) were computed overall and stratified by demographic characteristics. Using both T1 post-contrast (T1Gd) and T2-weighted images, the loss-based model achieved AUC=0.83 (95% CI: 0.77-0.88) and the ensemble model yielded an AUC=0.82 (95% CI: 0.76-0.89). Model performance was similar across males and females; however, model performance was better for subjects older than 50 years of age versus younger than 50. When using only T1Gd images, the loss-based model dropped to AUC=0.55 (95% CI: 0.48-0.63), whereas the ensemble model had AUC=0.79 (95% CI: 0.72-0.85). Models trained with only T2 images achieved AUCs of 0.67 (95% CI: 0.60-0.73) (loss-based) and 0.75 (95% CI: 0.69-0.82) (ensemble). These results highlight the added value of the multi-sequence input. Our results confirm the feasibility of using automated deep learning models to differentiate GBM from PCNSL. Notably, the model generalized well to external MRI data, emphasizing its potential utility as a diagnostic aid in real-world clinical workflows.

Abstract OBJECTIVE To demonstrate that Prostate-specific membrane antigen (PSMA) PET imaging, though primarily used in prostate cancer surveillance, can reveal PSMA uptake in non-prostatic tumors due to neovascular PSMA expression. BACKGROUND PSMA PET imaging is increasingly used for staging and monitoring prostate cancer. However, PSMA uptake is not exclusive to prostate carcinoma and may be observed in non-prostatic malignancies, including glioblastoma, due to neovascular expression. CASE REPORT We present a 67-year-old gentleman with metastatic prostate carcinoma, diagnosed in 2014 and treated with neoadjuvant Lupron, prostatectomy, and salvage radiation. In 2019, he developed nodal recurrence in retroperitoneal and bilateral iliac chain nodes, treated with lymphadenopathy, six cycles of Taxotere-based chemotherapy, and consolidative proton beam radiation (56.25 Gy/25 fractions). He later developed progression to the right proximal humerus and left coracoid process, treated with stereotactic body radiation therapy (25Gy/5 fractions). Follow-up PSMA PET/CT revealed no systemic abnormalities but showed a new PSMA-avid lesion in the right medial temporal lobe. Brain MRI confirmed a 3.5 x 1.7 x 2.5 cm ring-enhancing, intra-axial lesion with edema. The patient was asymptomatic. PSA was undetectable on abiraterone/prednisone and leuprolide. He underwent right frontotemporal craniotomy and resection. Pathology confirmed Glioblastoma, IDH-wildtype, CNS WHO Grade 4 with focal epithelioid features and positive MGMT promoter methylation. He received standard-of-care treatment with radiation, temozolomide, and TTF device. Surveillance PSMA PET and MRI showed no residual brain avidity or progression. Discussion: PSMA is a type II transmembrane glycoprotein expressed by prostatic and various non-prostatic tissues. In healthy brain parenchyma, PSMA expression is typically absent but is overexpressed in neovasculature of high-grade gliomas, including glioblastoma, IDH-wildtype, allowing for radiotracer uptake, as seen in this case. CONCLUSION This case illustrates the potential role of PSMA as a diagnostic tool, as it allows for easy identification of glioblastoma neovasculature, as demonstrated in our case report.

Abstract The 2021 WHO classification redefined glioblastoma IDH-wildtype (GBM), integrating histopathological and tumor molecular features. Diffuse astrocytic glioma lacking histologic features of necrosis and microvascular proliferation are classified as (molecular) GBM if the tumor is IDH- and H3-wildtype and has one or more additional tumor molecular alterations: TERT promoter mutation, EGFR amplification, or +7/-10. Due to the absence of histopathological features of classic GBM and presentation without enhancement on MRI in approximately 50% of cases, molecular GBM frequently resemble low-grade IDH-mutant gliomas. We hypothesized that MRI-based deep learning models could distinguish IDH-mutant glioma from molecular GBM. We retrospectively identified 97 individuals with molecular GBM, who were matched to 97 individuals with IDH-mutant glioma by age, sex, year of diagnosis, and enhancement on MRI. Of the 97 IDH-mutant gliomas, 51% were 1p/19q codeleted, 42% grade 2, 47% grade 3, and 10% grade 4. Preoperative postcontrast T1-weighted (T1C) and T2-weighted (T2) MRI sequences were used to train a 3D-DenseNet121 model. The model was validated on an independent prospective set of 150 IDH-mutant gliomas and 71 molecular GBM. The MRI-based deep learning model achieved an area under the receiver operator curve (AUC) of 0.75 (95% CI: 0.68-0.82) in the prospective validation set. Sex-stratified AUCs were 0.72 (95% CI: 0.59-0.85) for females and 0.76 (95% CI: 0.68-0.85) for males. Age stratified AUCs were 0.71 (95% CI: 0.60-0.83) for patients under 55 years of age and 0.64 (95% CI: 0.50-0.79) for patients older than 55. These results suggest that discriminative MRI features of IDH-mutant glioma and molecular GBM exist and can be identified from deep learning models. However, radiographic ambiguity exists and underscores the need for further optimization of the deep learning architecture or by integrating additional non-invasive modalities. For example, future work entails integrating germline variants into the model, including rs55705857, which is a causal variant for IDH-mutant glioma. With further validation and integration of multi-modal data, a noninvasive tool may support more personalized decision-making.

Abstract BACKGROUND High grade astrocytoma with piloid features (HGAP) is a newly recognized tumor with a distinct DNA methylation profile. Its clinical course, treatment response, and outcomes remain poorly understood. METHODS We conducted a retrospective cohort study across three Mayo Clinic sites including adults with a HGAP diagnosis confirmed by DNA methylation profiling. RESULTS 17 patients were included (median age 38 years, Q1, Q3: 29–59; 9 male). DNA methylation-based tumor classification using the NCI/Bethesda classifier (v2) indicated a match to HGAP with high confidence (calibrated score >0.9) in 14 cases and was suggestive in 3 cases. All had MAPK pathway alterations (NF-1 mutation in 11, FGFR1 mutation in 2, KIAA1549::BRAF fusion in 2, FGFR1 transcript variant suggestive of internal tandem duplication in 1, KANK2::NTRK2 fusion in 1). All tumors also had CDKN2A/B homozygous deletion and 9 lost ATRX expression. Tumors were infratentorial (n=8), supratentorial (n=7), and spinal (n=2) at initial presentation. First line treatment included surgery followed by chemoradiation with temozolomide (n=12), surgery followed by radiation (n=4), radiation alone (n=1), and surgery alone (n=1). Gross total resection was achieved in 3/17, 8/17 had subtotal resection and 5/17 had biopsy. 14/17 received a median RT dose of 5700 cGy (range, 4005–6000) in 30 fractions. The median follow-up duration was 34.9 months. 8 patients experienced disease progression. The median progression-free survival (mPFS) was 30.3 months (95% CI: 15.4–NR). 6/8 underwent surgery; 3/8 underwent RT. Systemic therapies were administered in 5/8 (lomustine, bevacizumab, pembrolizumab, temozolomide, trametinib, tovorafenib). 3/17 patients died due to progressive disease with an OS of 54.2, 94.6 and 17.4 months, respectively. The mOS for the whole cohort was 54.2 months (95% CI: 54.2-NR). CONCLUSION While the optimal management of this newly recognized entity has yet to be established, our cohort demonstrates a clinical behavior consistent with CNS WHO grade 3, aligning with current WHO interpretations.

Abstract BACKGROUND The Response Assessment in Neuro-Oncology (RANO) was recently updated to RANO 2.0, which no longer requires follow-up imaging to confirm progression in recurrent glioma patients recieving immunotherapy, as previously recommended by iRANO. This study evaluates the utility of RANO 2.0 to determine whether radiographic progression on initial post-treatment MRI is sufficient to guide timely discontinuation of ineffective therapy. METHODS This retrospective study, conducted at Mayo Clinic, included patients ≥18 years receiving ≥2 cycles of off-label pembrolizumab for recurrent glioma between 1/1/2014 – 5/1/2025. Radiographic response was assessed using the first MRI performed ≥30 days after pembrolizumab initiation. Progression was defined as a ≥25% increase in the product of perpendicular diameters of the lesion, clear progression of non-measurable disease, new lesion appearance, clinical deterioration, or death. For suspected pseudo-progression, sequential MRIs were reviewed; if progression was confirmed, the original date was used. RESULTS Sixty-two patients were included (mean age: 46.1 years; 64.5% male), receiving pembrolizumab for a median duration of 2.8 (1.4 – 19.4) months. Median time to initial radiographic response assessment was 1.6 (1.1 – 3.5) months, and progression-free survival was 2.3 (0.7 – 15.2) months. Thirty-seven (59.7%) patients were identified with progression at initial evaluation. Among them, 11 were initially suspected of pseudo-progression, and continued pembrolizumab: 3 received additional radiation, 2 initiated bevacizumab, while 6 remained on their prior regimens [pembrolizumab only (3); pembrolizumab with bevacizumab (3)]. However, all were subsequently confirmed to have true progression, with a median delay of 1.4 (0.7 – 7.1) months until pembrolizumab discontinuation. No true pseudo-progression cases were observed. CONCLUSIONS Our findings support the clinical applicability of RANO 2.0 in recurrent glioma patients receiving pembrolizumab. Initial radiographic progression reliably predicted true progression, suggesting limited value in confirmatory follow-up imaging. Early recognition of treatment failure may reduce delays in initiating salvage therapies, along with associated toxicity and cost.

Abstract BACKGROUND Tovorafenib is a type II rapidly accelerated fibrosarcoma (RAF) kinase inhibitor approved by the FDA in 2024 for relapsing or chemotherapy-refractory pediatric low-grade gliomas with mutations or alterations in the gene BRAF. There is potential for the use of this drug outside the pediatric population. We present a single institution case series of adults with CNS tumors with mutations or alterations in BRAF treated (off-label) with tovorafenib. METHODS Chart review. RESULTS 8 adult (age >18) patients were treated with tovorafenib at our institution between March 2024 and June 2025. Age range was 21-66 years old (median age 42). The population included 5 males and 3 females. Indications for treatment were pilocytic astrocytoma (n = 2), high grade astrocytoma with piloid features (HGAP) (n = 2), Erdheim-Chester disease (n = 2), pleomorphic xanthoastrocytoma (n = 1), and otherwise unclassified low-grade glioma (n = 1). All patients had mutations or alterations in BRAF including KIAA1549 fusion (n = 4), V600E mutation (n = 3), or GAB2 fusion (n = 1). Radiographic response to therapy was seen in 5/8 patients with 3 cases of radiographic stability (though one patient later progressed) and 2 cases of decrease in tumor size (in a pilocytic astrocytoma and in an HGAP). Both cases of decreased tumor size after treatment were in tumors with KIAA1549 fusions. Adverse effects of tovorafenib included fatigue (n=2), headache, myalgias, diplopia, cytopenias, and transaminitis (n=1). 3/8 patients had to pause or stop treatment due to adverse effects (intolerable headache, cytopenias, and transaminitis respectively). CONCLUSION Tovorafenib is a promising new treatment for CNS tumors with BRAF mutations or alterations. Our single institution case series suggests the efficacy of this drug for multiple tumor types in adults. Certain tumor subtypes such as KIAA1549 fusions may be more likely to benefit from this treatment.

Abstract BACKGROUND Bevacizumab, an anti-vascular endothelial growth factor (VEGF) monoclonal antibody, has emerged as a treatment for radiation necrosis. Doses ranging from 2.5 mg/kg to 15 mg/kg have been utilized however the optimal dosing remains inadequately studied. METHODS Retrospective review of adult patients with central nervous system tumors or brain metastasis treated with bevacizumab from 6/29/2021 to 7/31/2024. Patients were divided into those who received bevacizumab 7.5 mg/kg every 21 days and those who received bevacizumab 10 mg/kg every 21 days. The primary outcome was radiographic response as assessed by a blinded neuro-oncologist. Secondary outcomes included clinical response as documented in clinical notes, major adverse events including hemorrhage and thromboembolic events and re-dosing for recurrence of radiation necrosis beyond the 4 initially planned doses. RESULTS 104 patients were included (median age 59.3 years, 55% male); 53 patients in the 7.5 mg/kg group and 51 patients in the 10 mg/kg group. In the 7.5 mg/kg group, 1 patient had a complete response (CR), 16 patients had a partial response (PR), 32 patients had stable disease (SD), 3 patients had progression of disease, and 1 patient did not have repeat imaging. Of the 51 patients in the 10 mg/kg group, 3 patients had a CR, 10 patients had a PR, 27 patients had SD, 5 patients had progression of disease, and 6 patients did not have repeat imaging. There was no statistically significant difference in radiographic response between the two dosing groups (p = 0.42). Clinical response rates were higher in the 7.5 mg/kg group (65.2% vs 37.8%, p = 0.013). Major adverse events and need for re-dosing for radiation necrosis recurrence were comparable. CONCLUSION Bevacizumab 7.5 mg/kg was equally as efficacious as 10 mg/kg in terms of radiographic response and may offer a better clinical response for patients with radiation necrosis.

Abstract BACKGROUND Cognitive symptoms are common among cancer patients treated with intracranial radiation but inadequately assessed and suboptimally treated, owing in part to the time-consuming and resource-intensive nature of formal neuropsychological testing. Through remote administration of brief cognitive assessments and symptom-directed interventions, decentralization uniquely addresses this problem. METHODS In this single-site phase 2 fully decentralized clinical trial (NCT06377696), patients treated with radiation therapy (RT) for primary or metastatic brain tumors undergo cognitive evaluations with the application, Mayo Test Drive, and the Short Test of Mental Status (STMS; via telehealth or in person), at baseline and every three months for one year. Participants are provided wearable devices for health promotion. Half the participants are randomized to metformin to evaluate this agent’s efficacy in treating RT-related cognitive symptoms. Target enrollment is 100 participants. RESULTS Seventy-three patients (median age 45.5, 46% female) with brain tumors who received RT were enrolled May 2024 to May 2025. In this unplanned interim analysis, we evaluated the impact of decentralization on study participation. Thirty-six participants (49%) reported a primary residence greater than 150 miles from our institution. Seven patients were consented remotely, the remainder in person. Of 380 study-related visits (201 STMS, 179 treatment toxicity checks) 216 (57%) were completed by telehealth. Thirty-two of 336 (9.5%) study-related lab draws were completed at locations outside our institution. Wearable device data was continuously collected, with median 3022 steps tracked per patient per day on study. 190/250 (76%) quality-of-life surveys sent digitally were completed to date. CONCLUSION Decentralization implemented as part of this clinical trial enabled participation despite significant distance from our institution and facilitated study-related assessments through digital solutions, eliminating the need for travel. Our findings demonstrate the feasibility of conducting a fully decentralized supportive care trial in neuro-oncology, which can increase participation and accelerate evaluation of novel therapeutics.

Abstract BACKGROUND Bevacizumab, an anti-VEGF monoclonal antibody, has become a mainstay in the management of malignant gliomas. Multiple bevacizumab biosimilars have been approved since initial FDA approval of the reference agent and have seen widespread use due to reduced cost. However, real-world data evaluating comparability between reference and biosimilar agents have remained limited. METHODS We performed a retrospective analysis of patients treated with reference bevacizumab (Avastin) versus those receiving bevacizumab-bvzr, a widely used biosimilar agent (Zirabev) for the management of malignant glioma at our institution between 2019 and 2022. RESULTS A total of 161 patients were included in our final analysis; 97 received reference drug (Avastin) while 64 received the biosimilar agent (Zirabev). Demographics and baseline clinical characteristics between the two groups were similar. We performed survival analysis with post-progression survival (PPS) to ensure against lead-time bias. PPS was similar between the Avastin (median PPS 496 days) and Zirabev (median PPS 513 days) groups on univariate analysis (p=0.7654). Similarly, on multivariate Cox regression, there were no differences in PPS when comparing Avastin and Zirabev (HR 1.0673, p=0.6986). MGMT promoter methylation (HR 0.5709, p=0.0238), age at cancer diagnosis (HR 1.0356, p=0.0009), total dose of bevacizumab received (HR 0.9975, p=0.0087) and treatment with anticoagulation (HR 1.8086, p=0.0372) were significantly associated with PPS. Rates of therapy-related adverse effects were also similar between those receiving the reference drug and biosimilar agent (OR 0.9043, p=0.7824). However, concomitant treatment with antiplatelet therapy (OR 3.1447, p=0.0150) or anticoagulant therapy (OR 4.9069, p=0.0010) were significantly associated with increased risk for adverse effects. CONCLUSIONS Bevacizumab-bvzr demonstrated similar clinical efficacy and safety profile compared to reference bevacizumab in our institutional cohort. Concomitant treatment with antiplatelet therapy (OR 3.1447, p=0.0150) or anticoagulation (OR 4.9069, p=0.0010) were significantly associated with increased risk for adverse effects.