Uhm, Joon H.

Abstract Purpose Bevacizumab is an effective treatment for radiation necrosis; dose dependent radiographic and edema response data are lacking. Methods Multicenter, retrospective cohort study of adult patients with primary central nervous system tumors or brain metastases who received bevacizumab for radiation necrosis between June 2021 and July 2024. Patients were grouped by bevacizumab dose (7.5 mg/kg vs 10 mg/kg administered every three weeks). Primary outcome was edema response, assessed by a blinded neuro-oncologist. Secondary outcomes included contrast enhancing disease response, clinical response, adverse events, treatment discontinuation, and re-dosing for recurrent radiation necrosis. Analyses were performed with and without adjustment for tumor type. Results 104 patients were included (7.5 mg/kg, n = 53; 10 mg/kg, n = 51). Edema response differed between dosing groups in unadjusted analyses (p = 0.032), favoring the 7.5 mg/kg cohort; however, this association was attenuated after adjustment for tumor type. Contrast enhancing disease response did not differ between groups in either unadjusted or adjusted analyses (p = 0.43). Clinical response was higher in the 7.5 mg/kg group (65.2% vs 37.8%, p = 0.013). Tumor type differed significantly between cohorts (p < 0.001), with more primary CNS tumors in the 10 mg/kg group. Rates of adverse events, treatment discontinuation, and re-dosing were similar. Conclusions While lower-dose bevacizumab was associated with greater edema reduction in unadjusted analyses, this effect was attenuated after accounting for tumor type. Importantly, 7.5 mg/kg dosing appeared sufficient for achieving edema control and contrast enhancing disease response. These findings support an individualized approach to bevacizumab dosing in radiation necrosis and highlight the need for prospective, tumor-stratified studies.

Abstract Background: Glioma diagnosed during pregnancy and pregnancy following glioma treatment present complex management challenges. The safety of glioma treatment during pregnancy is not well established. The ability to counsel patients on timing of conception after treatment remains limited. The aim of this study was to review our institution’s experience with glioma during and before pregnancy. Methods: In this single-institution study, we retrospectively identified patients diagnosed with glioma during or prior to pregnancy and reviewed treatment course and maternal and neonatal outcomes. Results: Twenty-one female patients were included in our study. Glioma diagnoses included 12 high-grade tumors and 9 low-grade tumors. Cohort A consisted of 8 patients who presented with glioma during pregnancy, of which, 7 underwent glioma treatment during pregnancy. All pregnancies in cohort A were without significant maternal complications and resulted in delivery of a healthy neonate. Cohort B consisted of 13 patients who experienced pregnancy after a prior diagnosis of glioma, totaling 23 pregnancies. Antepartum course was complicated by seizure in three pregnancies. Functionally inconsequential anatomic abnormalities in childhood offspring of cohort B occurred in 5 (27.8%) of the pregnancies. Four of the offspring with anatomic abnormalities had exposure to TMZ prior to conception. Conclusions: In this retrospective series, diagnosis of glioma before or during pregnancy was associated with generally favorable maternal, fetal and childhood outcomes. We observed a higher-than-expected rate of anatomic abnormalities in the post-diagnosis cohort, though none carried meaningful functional consequences. These findings add to the limited literature exploring maternal and fetal outcomes in patients with glioma.

Abstract Background Isocitrate dehydrogenase-1 (IDH-1) inhibitor ivosidenib and dual-IDH1/2 inhibitor vorasidenib have demonstrated clinical activity in the treatment of IDH-mutant gliomas. We evaluated the efficacy of vorasidenib in patients with prior exposure to ivosidenib. Methods Retrospective review of patients with IDH-mutant glioma treated with vorasidenib who had prior treatment with ivosidenib. Previous treatments, radiographic response, and adverse events were collected and analyzed descriptively. Results Twenty-nine patients (median age 42, 34% female) were evaluated. Tumor types included IDH-mutant astrocytoma (grade 2 n = 9, 31%; grade 3 n = 3, 10%; grade 4 n = 3, 10%) and oligodendroglioma (grade 2 n = 10, 34%; grade 3 n = 4, 14%). Treatments received prior to ivosidenib included surgical resection (n = 23, 79%), radiation (n = 16, 55%), temozolomide (n = 15, 52%), procarbazine, lomustine, vincristine (PCV, n = 2, 7%), bevacizumab (n = 3, 10%), lomustine (n = 2, 7%), and pembrolizumab (n = 1, 3%). Four patients received additional treatment in between ivosidenib and vorasidenib treatment. Ten of 16 (63%) patients who experienced disease progression on ivosidenib achieved stable disease and remain on vorasidenib, while 6 (37%) had continued progression. Eleven patients with stable disease on ivosidenib transitioned to vorasidenib following FDA approval and remained without progression. Two patients who transitioned to vorasidenib due to ivosidenib-related adverse effects (diarrhea and fatigue) experienced symptom resolution and maintained disease stability. Conclusions Vorasidenib demonstrated clinical efficacy in patients with IDH-mutant gliomas previously treated with ivosidenib. Notably, stable patients who transitioned maintained disease stability, while some of those with progressive disease achieved stabilization with vorasidenib. These findings support vorasidenib as a viable therapeutic option following ivosidenib exposure.

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 &gt;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 &gt; 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 &gt;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.

9523 Background: Primary Central Nervous System (CNS) Melanoma is a rare and aggressive malignancy, comprising 1% of melanoma cases and 0.07% of brain tumors. Due to its rarity, its natural history, molecular features and optimal management remain poorly defined. Methods: We retrospectively reviewed patients at our institution between January 1998 and October 2025 with primary CNS melanoma or melanocytoma with melanoma transformation. Clinical characteristics, molecular profiling, treatments and survival outcomes were collected. Overall survival (OS) and progression free survival (PFS) were estimated using Kaplan-Meier curves. Results: Nineteen patients were identified, including eight (42%) with melanocytoma to melanoma transformation. Median time of transformation was 34.4 months. Thirteen (68%) patients were female with a median age at diagnosis of 59.3 years. Common presenting symptoms were sensory disturbances (58%), pain (53%), motor deficits (37%) and nausea or vomiting (32%). At diagnosis, location of disease was spinal (n=12), intracranial (n=6) and multifocal (n=1). Thirteen patients had leptomeningeal involvement. Molecular profiling was performed in 15 patients, revealing mutations in GNAQ (n=7), GNA11 (n=3), CKIT (n=2), BAP1 (n=1), EIF1AX (n=1), and BRAF v600 (n=1). Thirteen (68%) patients underwent subtotal resection (STR), five (26%) gross total resection (GTR) and one radiation only. Median resected tumor size was 1.7 cm. Seventeen (94%) patients had recurrence at a median of 9.1 months, and four patients underwent repeat surgery. Fourteen (74%) patients received adjuvant radiation and 14 (74%) received immunotherapy, most commonly ipilimumab with nivolumab (71%). Nine patients received chemotherapy: temozolomide (n=5), bevacizumab (n=2) and one each of intrathecal IL-2, tebentafusp, imatinib and encorafenib with binimetininb. Four patients received chemotherapy before immunotherapy. Median OS from diagnosis of CNS melanocytoma or melanoma was 50.9 months (13.4 – 80). Median OS from time of transformation to melanoma or CNS melanoma diagnosis was 24.0 months (11.9 – NA). One-, three- and five-year OS rates were 73%, 53% and 40% respectively. GTR was associated with increased median OS compared to STR (80.0 vs 19.7 months, p= 0.02). Age at diagnosis, immunotherapy, chemotherapy, adjuvant radiation, STR with or without radiation, disease location, leptomeningeal involvement, tumor size >3cm and presence of GNAQ mutation were not associated with survival. Median PFS was 3 months with chemotherapy and 5.7 months with immunotherapy. Conclusions: To our knowledge, this is the largest single center study of primary CNS melanoma. Outcomes remain poor, with survival primarily associated with GTR. The predominance of GNAQ and GNA11 alterations with rare BRAF v600 mutations highlight the distinct biology of primary CNS melanoma and need for novel targeted therapies.

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: Pembrolizumab has been increasingly used off label for recurrent gliomas, yet biomarkers predicting response are poorly defined. Gliomas exhibit substantial molecular heterogeneity across Glioblastoma, IDH-wildtype (GBM), Astrocytoma, IDH-Mutant (A-IDHm), and Oligodendroglioma, 1p/19q co-deleted (OLIGO), which may influence immunotherapy efficacy. This study aimed to identify molecular predictors of progression-free survival (PFS) in recurrent glioma patients treated with pembrolizumab. Methods: Adults ≥18 years with recurrent glioma receiving ≥2 cycles of pembrolizumab between 2014 - 2024 were retrospectively identified across Mayo Clinic. Next-generation sequencing (NGS) reports were reviewed and archival tumor tissue resected prior to pembrolizumab initiation was analyzed when available. Comprehensive molecular profiling was performed using the Mayo Clinic Solid Tumor Panel which employs the Illumina Tru-Sight Oncology 500 High-Throughput NGS assay. Progression was assessed using RANO 2.0 criteria. Genomic alterations (clinically relevant sequences and/or copy-number variants) were evaluated using the Kaplan-Meier method, with differences in PFS compared using the log-rank test. Results: Thirty-three patients were included [median (range) age: 44.0 (21-76) years; 63.6% male]. The interval between tumor tissue sampling and pembrolizumab initiation was 9.9 (0.9-176.1) months, and median treatment duration was 2.8 (1.4-10.4) months. Median PFS for the overall cohort was 2.4 (0.8-15.2) months, and median overall survival from pembrolizumab initiation was 6.9 (0.9-48.2) months. Patients with OLIGO (n=8) had a longer PFS [4.6 (1.9-15.2) months] than either A-IDHm [n=11; PFS 2.1 (1.1-4.4) months] or GBM [n=14; PFS 2.3 (0.8-9.2) months]. Within OLIGO, CDKN2A/B heterozygous deletion (n=3) predicted a shorter PFS (3.9 vs 10.9 months; p=0.0462), while in A-IDHm, FANC mutation (n=2) was associated with a longer PFS (4.17 vs 1.61 months; p=0.0224). No significant associations with PFS were observed for other altered genes or pathways evaluated, including but not limited to Tumor Mutational Burden, EGFR, RB1, TP53, FUBP1, NF 1 or 2, PTEN, PDGFRA, PIK3CA, PIK3R1, CDK4, KRAS, MLH1, MLH2, MSH6 genomic alterations or CDKN2A/B homozygous deletion (all p&gt;0.05). Conclusions: Pembrolizumab shows limited overall efficacy in recurrent gliomas, however, exploratory analyses identified several subtype-specific genomic alterations that may correlate with PFS. These hypothesis-generating findings highlight the potential influence of underlying tumor biology on immunotherapy response and warrant further validation in larger, prospective cohorts. Citation Format: Shameel Shafqat, Muhammad Asad Maqbool, Hussam Al Kateb, Terry C. Burns, Jian L. Campian, Shannon P. Fortin Ensign, Evanthia Galanis, Julie E. Hammack, Cristaine M. Ida, Mitch L. Klebig, Timothy J. Kaufmann, Autumn C. Moon, Maciej M. Mrugala, Bryan J. Neth, Alyx B. aPorter, Michael W. Ruff, Ugur T. Sener, Wendy J. Sherman, Joon H. Uhm, Rachael A. Vaubel, Sani H. Kizilbash. Molecular correlates of progression-free survival in recurrent gliomas treated with pembrolizumab [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 5253.

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.