Lehrer, Eric J.

Abstract Background The current treatment of glioblastoma involves resection followed by radiotherapy (RT) and temozolomide. Rapid early progression (REP) of tumor in the surgery-to-radiotherapy interval (SRI) has been described using categorical or semi-quantitative assessments and is associated with inferior clinical outcomes. This study seeks to establish and validate a quantitative definition for REP and examine how REP could inform future therapy. Methods Volumes of tumor and resection cavity at 3 time points—preoperative, postoperative and RT-planning (pre-RT)—were contoured among patients who had undergone standard of care. A minimal, but clinically appreciable, threshold for defining REP based on change in tumor volume was established, validated, and subsequently used to assess actionable predictors of REP and its prognostic value. Results An increase of >2 cc in volume or a new satellite tumor between the post-operative to planning MRI was found to be a sensitive, pragmatic, and statistically significant cutoff for REP (P = .002). Actionable predictors such as SRI of 6 weeks and a > 5 cc residual immediate post-operative tumor volume were found to be statistically significant predictors of REP. REP was also found to be a statistically significant prognostic indicator for overall survival (P = .002) and progression-free survival. Conclusion These findings support that an increase in tumor volume between post-operative and pre-RT MRI of >2 cc is the ideal working definition of REP in this clinical setting. Furthermore, REP could serve as a prognostic ­biomarker to track treatment response. Additionally, 2 actionable predictors of REP, post-op residual tumor volume and SRI, are identified.

e14017 Background: The role of stereotactic radiosurgery (SRS) is well established in the setting of one to four brain metastases (BM), offering effective control with reduced neurocognitive toxicity compared with whole-brain radiotherapy (WBRT). However, for patients with five or more BM, the optimal radiation strategy remains uncertain, and comparative outcome data are limited. We performed a systematic review and meta-analysis to compare overall survival (OS) between SRS and WBRT in patients with ≥ 5 BM. Methods: A systematic review was conducted to identify comparative studies of SRS versus WBRT in patients with ≥5 brain metastases. Retrospective and prospective studies reporting median OS with available cohort sizes were included. Comparative survival was summarized using pooled ratios of median survival within a random-effects meta-analytic framework. Results: Five comparative studies were included, comprising 226 patients treated with SRS and 261 treated with WBRT, including both retrospective and prospective cohorts. Sample-size–weighted summary (with reported medians) showed median OS was 8.1 months with SRS and 7.7 months with WBRT. Pooled analysis demonstrated no significant difference in OS between treatment strategies (ratio of median survival, 1.03; 95% CI, 0.73–1.46; p = 0.81). Conclusions: Among patients with ≥5 BM, SRS and WBRT were associated with comparable OS. These data suggest that OS alone may not guide treatment choice in this population, emphasizing the importance of careful patient selection. As focal therapies are increasingly incorporated into clinical practice for patients with higher intracranial disease burden, prospective, multi-institutional randomized clinical trials are needed to better define optimal management strategies. Summary of included studies reporting median overall survival (OS). Study Study Design SRS (n) WBRT (n) Median OS in SRS cohort (months) Median OS in WBRT cohort (months) Kim et al., 2009 Retrospective 29 39 5.6 7.2 Mizuno et al., 2019 Retrospective 24 20 7.3 7 .2 Li et al., 2020 Prospective, randomized 35 34 7.8 8.9 Bodensohn et al., 2023 Prospective, non-randomized 40 70 10.4 6.5 Aizer et al., 2025 Prospective, randomized 98 98 8.3 8.5

e14016 Background: Postoperative stereotactic radiosurgery (SRS) is utilized following resection of brain metastases (BM), however use is limited by target delineation uncertainty and an increased risk of leptomeningeal disease (LMD). Preoperative SRS allows for precise targeting and is being increasingly utilized in treatment paradigms of resectable BM. Reported outcomes across studies are promising and there are several phase 3 trials which are underway. Therefore, we pooled multiple studies and conducted a meta-analysis to estimate 1-year local control (LC), LMD incidence, and overall survival (OS) following single-fraction preoperative SRS for resectable BM. Methods: We systematically searched PubMed, Embase, and Scopus to identify studies of single-fraction preoperative SRS for resectable BM. For each cohort, data for 1-year LC, 1-year LMD, and 1-year OS, along with corresponding sample sizes, were extracted. A proportion-based meta-analysis was performed to derive pooled estimates and 95% confidence intervals (CIs), with between-study heterogeneity quantified using I². Results: Ten studies published between 2016 and 2025, including both prospective trials and retrospective cohorts, met the inclusion criteria. There were 617 patients treated with single-fraction preoperative SRS. The median age was 60.8 years (range 58-65 years), and the median prescribed dose was 15.8 Gy (range 14.5-17.0 Gy). The pooled 1-year LC rate was 81.9% (95% CI, 76.9-85.9; I² = 43.4%). The pooled 1-year incidence of LMD was 4.6% (95% CI, 2.8-7.4; I² = 0%), and the pooled 1-year OS rate was 60.2% (95% CI, 55.5-64.8; I² = 0%). Sensitivity analyses showed stable pooled estimates, with no single study driving the results. Conclusions: Single-fraction preoperative SRS is associated with low rates of LMD and acceptable LC and OS. In the context of historically reported postoperative SRS outcomes, these results suggest that preoperative SRS represents a promising strategy in selected patients. Randomized trials are needed to define the comparative role and optimal patient selection for preoperative SRS, with ongoing studies (NCT05341739, NCT03741673) expected to clarify its role in the management of resectable BM. Study characteristics and reported outcomes of single-fraction preoperative SRS for BM. Study Study design Number of patients Median age (years) Median dose (Gy) 1-year LTC (%) 1-year LMD (%) 1 year OS (%) Agarwal, 2024 Trial 47 59 NR NR 4.8 NR Higazy, 2025 Trial 35 61 17 82 2.86 NR Li, 2022 Retrospective 24 64 NR 87.6 NR NR Mallela, 2024 Retrospective 26 64.5 NR 77.2 NR NR Murphy, 2024 Trial 35 63 NR 76.6 NR 59 Patel, 2018 Retrospective 12 57.5 NR 49.1 10 74.1 Patel, 2016 Retrospective 66 58.2 14.5 84.1 3.2 NR Prabhu, 2025 Retrospective 124 NR 17 87.2 1.7 64.5 Prabhu, 2025 Retrospective 183 NR 15 86.4 7.3 58.1 Prabhu, 2020 Retrospective 65 NR NR 77.1 4.2 56.3

Abstract Background Vorasidenib is Food and Drug Administration‐approved for treatment of grade 2 isocitrate dehydrogenase (IDH)–mutant gliomas and has demonstrated a benefit in progression‐free survival compared to a placebo. This study assessed the cost‐effectiveness of this treatment strategy compared to standard treatment: observation or chemoradiation (CRT). Methods The authors used an integrated Markov model to compare quality‐adjusted life‐years (QALY) gained and cost‐effectiveness of patients with IDH‐mutated low‐grade glioma (LGG) treated with vorasidenib, observation, or CRT. Outcomes were expressed as incremental cost‐effectiveness ratios (ICERs) per QALY gained. Treatment is considered cost‐effective if it meets the commonly accepted willingness‐to‐pay threshold of $100,000 per QALY gained. Results Based on model parameters, vorasidenib demonstrated an ICER of $356,756 per QALY when compared to CRT. When compared to observation, vorasidenib demonstrated an improved ICER of $215,191 per QALY. On one‐way sensitivity analysis compared to observation, median cost of vorasidenib and median overall survival were most likely to affect ICER with only marginal changes on analysis of other model factors. For ICER to become ≤$100,000 compared to observation, the cost of vorasidenib would need to drop to below $14,072 monthly or have a median survival gain of at least 11.9 years. The probabilistic sensitivity analysis demonstrated that vorasidenib was favored in none of 5000 Monte Carlo iterations. Conclusion Using the best available data, the current price of vorasidenib does not meet commonly accepted cost‐effectiveness thresholds in treatment of IDH‐mutated LGGs.

Abstract Background Isocitrate dehydrogenase (IDH)-mutant gliomas are infiltrative tumors with limited treatment options at recurrence. Early studies suggest IDH inhibition has therapeutic activity. We evaluated clinical outcomes associated with IDH-1 inhibitor ivosidenib in recurrent IDH-1-mutant gliomas and molecular predictors of response. Methods We retrospectively analyzed adults treated with ivosidenib from January 2021 to August 2025 with predominantly recurrent, pretreated CNS WHO grade 2-4 astrocytoma IDH-mutant or grade 2-3 oligodendroglioma, IDH-mutant and 1p/19q codeleted. Prior anticancer treatments, toxicities, enhancement status at ivosidenib initiation, and genomic alterations were collected. The primary endpoint was progression-free survival (PFS); secondary analyses evaluated associations between PFS, genomic complexity, and CDKN2A/B homozygous deletion. Results Ninety-two adults, median age 43, were included: 61 astrocytomas and 31 oligodendrogliomas, mostly grade 2. Before ivosidenib, 69 had surgery, 64 chemotherapy, and 64 radiation. Median time from diagnosis to ivosidenib was 4.8 years, with median of two prior progressions. Median treatment duration was 5.8 months. Median PFS was 15.2, 4.6, and 2.1 months for astrocytoma grades 2-4, 14.0 and 6.9 months for oligodendroglioma grades 2-3. Increasing genomic complexity was associated with shorter PFS in univariate analysis. Patients without CDKN2A/B homozygous deletion had median PFS of 19.2 months. Two patients with homozygous deletion had median PFS of 0.6 months. Conclusions In this retrospective analysis of predominantly recurrent IDH-1-mutant glioma, ivosidenib was associated with longer PFS in lower-grade, non-enhancing tumors that received little or no prior anticancer treatment and less complex genomic profiles. These findings support a context-dependent benefit of IDH inhibition in recurrent disease.

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 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 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.