Analysis of upfront resection or stereotactic radiosurgery for local control of solid and cystic cerebellar hemangioblastomas

OBJECTIVE

The purpose of this study was to identify rates of and risk factors for local tumor progression in patients who had undergone surgery or radiosurgery for the management of cerebellar hemangioblastoma and to describe treatments pursued following tumor progression.

METHODS

The authors conducted a retrospective single-center review of patients who had undergone treatment of a cerebellar hemangioblastoma with either surgery or stereotactic radiosurgery (SRS) between 1996 and 2019. Univariate and multivariate regression analyses were performed to examine factors associated with local tumor control.

RESULTS

One hundred nine patients met the study inclusion criteria. Overall, these patients had a total of 577 hemangioblastomas, 229 of which were located in the cerebellum. The surgical and SRS cohorts consisted of 106 and 123 cerebellar hemangioblastomas, respectively. For patients undergoing surgery, tumors were treated with subtotal resection and gross-total resection in 5.7% and 94.3% of cases, respectively. For patients receiving SRS, the mean target volume was 0.71 cm3 and the mean margin dose was 18.0 Gy. Five-year freedom from lesion progression for the surgical and SRS groups was 99% and 82%, respectively. The surgical and SRS cohorts contained 32% versus 97% von Hippel-Lindau tumors, 78% versus 7% cystic hemangioblastomas, and 12.8- versus 0.56-cm3 mean tumor volumes, respectively. On multivariate analysis, factors associated with local tumor progression in the SRS group included older patient age (HR 1.06, 95% CI 1.03-1.09, p < 0.001) and a cystic component (HR 9.0, 95% CI 2.03-32.0, p = 0.001). Repeat SRS as salvage therapy was used more often for smaller tumor recurrences, and no tumor recurrences of < 1.0 cm3 required additional salvage surgery following repeat SRS.

CONCLUSIONS

Both surgery and SRS achieve high rates of local control of hemangioblastomas. Age and cystic features are associated with local progression after SRS treatment for cerebellar hemangioblastomas. In cases of local tumor recurrence, salvage surgery and repeat SRS are valid forms of treatment to achieve local tumor control, although resection may be preferable for larger recurrences.

Adverse radiation effect versus tumor progression following stereotactic radiosurgery for brain metastases: Implications of radiologic uncertainty

BACKGROUND

Adverse radiation effect (ARE) following stereotactic radiosurgery (SRS) for brain metastases is challenging to distinguish from tumor progression. This study characterizes the clinical implications of radiologic uncertainty (RU).

METHODS

Cases reviewed retrospectively at a single-institutional, multi-disciplinary SRS Tumor Board between 2015-2022 for RU following SRS were identified. Treatment history, diagnostic or therapeutic interventions performed upon RU resolution, and development of neurologic deficits surrounding intervention were obtained from the medical record. Differences in lesion volume and maximum diameter at RU onset versus resolution were compared with paired t-tests. Median time from RU onset to resolution was estimated using the Kaplan-Meier method. Univariate and multivariate associations between clinical characteristics and time to RU resolution were assessed with Cox proportional-hazards regression.

RESULTS

Among 128 lesions with RU, 23.5% had undergone ≥ 2 courses of radiation. Median maximum diameter (20 vs. 16 mm, p < 0.001) and volume (2.7 vs. 1.5 cc, p < 0.001) were larger upon RU resolution versus onset. RU resolution took > 6 and > 12 months in 25% and 7% of cases, respectively. Higher total EQD2 prior to RU onset (HR = 0.45, p = 0.03) and use of MR perfusion (HR = 0.56, p = 0.001) correlated with shorter time to resolution; larger volume (HR = 1.05, p = 0.006) portended longer time to resolution. Most lesions (57%) were diagnosed as ARE. Most patients (58%) underwent an intervention upon RU resolution; of these, 38% developed a neurologic deficit surrounding intervention.

CONCLUSIONS

RU resolution took > 6 months in > 25% of cases. RU may lead to suboptimal outcomes and symptom burden. Improved characterization of post-SRS RU is needed.

Epigenetic reprogramming shapes the cellular landscape of schwannoma

Mechanisms specifying cancer cell states and response to therapy are incompletely understood. Here we show epigenetic reprogramming shapes the cellular landscape of schwannomas, the most common tumors of the peripheral nervous system. We find schwannomas are comprised of 2 molecular groups that are distinguished by activation of neural crest or nerve injury pathways that specify tumor cell states and the architecture of the tumor immune microenvironment. Moreover, we find radiotherapy is sufficient for interconversion of neural crest schwannomas to immune-enriched schwannomas through epigenetic and metabolic reprogramming. To define mechanisms underlying schwannoma groups, we develop a technique for simultaneous interrogation of chromatin accessibility and gene expression coupled with genetic and therapeutic perturbations in single-nuclei. Our results elucidate a framework for understanding epigenetic drivers of tumor evolution and establish a paradigm of epigenetic and metabolic reprograming of cancer cells that shapes the immune microenvironment in response to radiotherapy.

Targeted gene expression profiling predicts meningioma outcomes and radiotherapy responses

Surgery is the mainstay of treatment for meningioma, the most common primary intracranial tumor, but improvements in meningioma risk stratification are needed and indications for postoperative radiotherapy are controversial. Here we develop a targeted gene expression biomarker that predicts meningioma outcomes and radiotherapy responses. Using a discovery cohort of 173 meningiomas, we developed a 34-gene expression risk score and performed clinical and analytical validation of this biomarker on independent meningiomas from 12 institutions across 3 continents (N = 1,856), including 103 meningiomas from a prospective clinical trial. The gene expression biomarker improved discrimination of outcomes compared with all other systems tested (N = 9) in the clinical validation cohort for local recurrence (5-year area under the curve (AUC) 0.81) and overall survival (5-year AUC 0.80). The increase in AUC compared with the standard of care, World Health Organization 2021 grade, was 0.11 for local recurrence (95% confidence interval 0.07 to 0.17, P < 0.001). The gene expression biomarker identified meningiomas benefiting from postoperative radiotherapy (hazard ratio 0.54, 95% confidence interval 0.37 to 0.78, P = 0.0001) and suggested postoperative management could be refined for 29.8% of patients. In sum, our results identify a targeted gene expression biomarker that improves discrimination of meningioma outcomes, including prediction of postoperative radiotherapy responses.

Adjuvant Chemoradiotherapy within One Year of Resection for Molecularly Defined Astrocytoma

PURPOSE/OBJECTIVE(S)

Treatments for diffuse low-grade gliomas (LGG) are controversial. Level I evidence supports the use of adjuvant radiotherapy (RT) and PCV chemotherapy for histologic LGG, but integration of molecular biomarkers in recent WHO classification and the emergence of temozolomide chemotherapy for gliomas necessitates additional investigation of the optimal treatment and timing of postoperative interventions. We hypothesized molecularly-defined LGG (IDH-mutant astrocytoma (astro) and IDH-mutant, 1p/19q-codeleted oligodendroglioma (oligo)) may have different clinical outcomes following adjuvant RT (aRT) with chemotherapy (aRT+chemo) vs observation or chemo alone.

MATERIALS/METHODS

A retrospective analysis of consecutive adult patients diagnosed with WHO Grade 2 astrocytoma or oligodendroglioma who underwent initial resection at a single institution from January 1998 to November 2017 was performed. Wilcoxon rank sum and Chi-squared tests were used to compare continuous and categorical variables, respectively. Survival analyses were performed using the Kaplan-Meier method and Cox proportional hazards models. Patients without clinical progression or death were censored at the date of last follow-up. Pre-operative and post-operative T2 FLAIR hyperintense tumor volumes were quantified using 3D Slicer to calculate extent of resection (EOR).

RESULTS

A total of 342 patients with molecularly-defined LGG (178 astro, 164 oligo) were identified with a median follow up of 9.1 yr. 171 (50%) patients received RT during their treatment course, of which 31 (18%) were treated with aRT within 1 year of diagnosis. The median aRT dose was 54 Gy (range: 40-60 Gy). aRT was more likely for astro (58%) vs oligo (41%, p = 0.001) and for patients who had resections with lower median EOR (88% vs 95%, p = 0.014). 53 patients (15%) were treated with chemo alone, and 136 patients (40%) were treated with aRT+chemo. Temozolomide was used for 161 patients (85%). For astro, aRT+chemo was associated with longer PFS (median 14.9 yr) compared to observation (4.8 yr, p = 0.05), aRT without chemo (5.2 yr, p = 0.01), or chemo alone (4.7 yr, p = 0.02). For oligo, aRT+chemo was associated with longer PFS (median not reached) compared to aRT without chemo (1.6 yr, p = 0.03), but not when compared to observation (median not reached, p = 0.47), or chemo alone (7.9 yr, p = 0.45). Multivariate analysis showed preoperative tumor volume, EOR, and aRT+chemo (but not aRT or chemo alone) were independently associated with astro PFS compared to observation. Propensity matching based on pre-operative tumor volume, EOR, and age demonstrated longer astro PFS after aRT+chemo (14.9 yr) compared to observation or chemo alone (4.5 yr, p = 0.015), without significant difference in OS (18.2 vs. 11.5 yr, p = 0.40).

CONCLUSION

Retrospective data from a single institution support the use of adjuvant radiotherapy with chemotherapy for patients with molecular astrocytomas, while the role of this approach for oligodendrogliomas is unclear in this cohort.

Mutational Status and Clinical Outcomes Following Systemic Therapy with or without Focal Radiation for Resected Melanoma Brain Metastases

BACKGROUND

Brain metastases occur frequently in advanced melanoma and traditionally require surgery and radiation therapy. New evidence demonstrates that systemic therapies are effective for controlling metastatic melanoma brain metastases. This study evaluated outcomes after resection of melanoma brain metastases treated with systemic therapy, with or without focal radiotherapy.

METHODS

All patients received immunotherapy or BRAF/MEK inhibitors preoperatively or in the immediate 3 months postoperatively. Resection cavity failure, distant central nervous system progression, and adverse radiation effects were reported in the presence and absence of focal radiotherapy using the Kaplan-Meier method.

RESULTS

Between 2011 and 2020, 37 resection cavities in 29 patients met criteria for analysis. Of lesions, 22 (59%) were treated with focal radiotherapy, and 15 (41%) were treated with targeted therapy or immunotherapy alone. The 12- and 24-month freedom from local recurrence was 64.8% (95% confidence interval [CI] 42.1%-99.8%) and 46.3% (95% CI 24.5%-87.5%), respectively, for systemic therapy alone and 93.3% (95% CI 81.5%-100%) at both time points for focal radiotherapy (P = 0.01). On univariate analysis, focal radiotherapy was the only significant factor associated with reduction of local recurrence risk (hazard ratio 0.10, 95% CI 0.01-0.85; P = 0.04). There were no significant differences in central nervous system progression-free survival or overall survival between patients who received systemic therapy plus focal radiotherapy compared with systemic therapy alone. BRAF mutation status was reviewed for either the brain metastasis (n = 9 patients, 31%) or the primary site (n = 20 patients, 69%), and patients harboring BRAFV600E mutations had worse progression-free survival (P = 0.043).

CONCLUSIONS

Focal radiotherapy with systemic therapy for resected melanoma brain metastases significantly decreased resection cavity recurrence compared with systemic therapy alone. BRAF mutation status correlated with poorer outcomes.

Stereotactic Radiosurgery for Primary Central Nervous System Lymphoma

Background Primary central nervous system lymphoma (PCNSL) is rare, with a treatment backbone that typically includes high-dose methotrexate-based chemotherapy, with radiation often reserved for persistent or progressive disease. In this study, we report the outcomes of stereotactic radiosurgery (SRS) in patients with PCNSL to potentially defer whole brain radiotherapy (WBRT) or as salvage after WBRT. Methodology We performed a single-institution, retrospective review of 20 patients with PCNSL who received single-fraction or fractionated SRS to 32 lesions between September 1992 and July 2019. Results The median age at SRS was 67 years (interquartile range (IQR) = 56-74 years). The median Karnofsky Performance Status (KPS) at SRS was 80 (IQR = 50-80). In total, 18 (90%) patients received methotrexate-based chemotherapy prior to SRS, with a median of eight cycles (IQR = 5-10). A total of 10 patients received SRS for recurrent disease after chemotherapy and/or WBRT, nine patients received SRS for the persistent disease after chemotherapy alone, and one patient received up-front SRS. Overall, five patients received SRS following WBRT. The median SRS dose was 16 Gy (IQR = 14-22.5 Gy) in one fraction (IQR = 1-5 fractions). Eight patients (40%) were treated with consolidative pomalidomide or lenalidomide following SRS. The local control rate was 100% (32/32 lesions at a median follow-up of 15 months). In total, 13 of 16 (81%) patients with available follow-up experienced distant brain recurrence. The median time to distant failure following SRS was 10 months (IQR = 1-16 months). Three patients received salvage SRS, and three patients received salvage WBRT. The median overall survival from diagnosis was 39 months (95% confidence interval = 24-54 months). KPS at the time of SRS was significantly correlated with time to progression (p = 0.002). The use of lenalidomide or pomalidomide after SRS was associated with improved overall survival after SRS (three vs. 14 months, p = 0.035). Consolidative etoposide and cytarabine after initial methotrexate-based chemotherapy was also associated with improved survival following SRS (eight vs. 47 months, p = 0.028). Conclusions SRS offers effective local tumor control for patients with PCNSL; however, the majority of patients experience distant progression. SRS may have a role in the salvage setting for patients with recurrence after WBRT, or allow deferral of WBRT in select patients, although systemic therapy appears to strongly influence outcomes in this cohort.

Adverse radiation effect and freedom from progression following repeat stereotactic radiosurgery for brain metastases

OBJECTIVE

The authors previously evaluated risk and time course of adverse radiation effects (AREs) following stereotactic radiosurgery (SRS) for brain metastases, excluding lesions treated after prior SRS. In the present analysis they focus specifically on single-fraction salvage SRS to brain metastases previously treated with SRS or hypofractionated SRS (HFSRS), evaluating freedom from progression (FFP) and the risk and time course of AREs.

METHODS

Brain metastases treated from September 1998 to May 2019 with single-fraction SRS after prior SRS or HFSRS were analyzed. Serial follow-up magnetic resonance imaging (MRI) and surgical pathology reports were reviewed to score local treatment failure and AREs. The Kaplan-Meier method was used to estimate FFP and risk of ARE measured from the date of repeat SRS with censoring at the last brain MRI.

RESULTS

A total of 229 retreated brain metastases in 124 patients were evaluable. The most common primary cancers were breast, lung, and melanoma. The median interval from prior SRS/HFSRS to repeat SRS was 15.4 months, the median prescription dose was 18 Gy, and the median duration of follow-up imaging was 14.5 months. At 1 year after repeat SRS, FFP was 80% and the risk of symptomatic ARE was 11%. The 1-year risk of imaging changes, including asymptomatic RE and symptomatic ARE, was 30%. Among lesions that demonstrated RE, the median time to onset was 6.7 months (IQR 4.7-9.9 months) and the median time to peak imaging changes was 10.1 months (IQR 5.6-13.6 months). Lesion size by quadratic mean diameter (QMD) showed similar results for QMDs ranging from 0.75 to 2.0 cm (1-year FFP 82%, 1-year risk of symptomatic ARE 11%). For QMD < 0.75 cm, the 1-year FFP was 86% and the 1-year risk of symptomatic ARE was only 2%. Outcomes were worse for QMDs 2.01-3.0 cm (1-year FFP 65%, 1-year risk of symptomatic ARE 24%). The risk of symptomatic ARE was not increased with tyrosine kinase inhibitors or immunotherapy before or after repeat SRS.

CONCLUSIONS

RE on imaging was common after repeat SRS (30% at 1 year), but the risk of a symptomatic ARE was much less (11% at 1 year). The results of repeat single-fraction SRS were good for brain metastases ≤ 2 cm. The authors recommend an interval ≥ 6 months from prior SRS and a prescription dose ≥ 18 Gy. Alternatives such as HFSRS, laser interstitial thermal therapy, or resection with adjuvant radiation should be considered for recurrent brain metastases > 2 cm.

Resection with intraoperative cesium-131 brachytherapy as salvage therapy for recurrent brain tumors

OBJECTIVE

The authors' objective was to examine the safety and efficacy of salvage intracranial cesium-131 brachytherapy in combination with resection of recurrent brain tumors.

METHODS

The authors conducted a retrospective chart review of consecutive patients treated with intraoperative intracranial cesium-131 brachytherapy at a single institution. Permanent suture-stranded cesium-131 seeds were implanted in the resection cavity after maximal safe tumor resection. The primary outcomes of interest were local, locoregional (within 1 cm), and intracranial control, as well as rates of overall survival (OS), neurological death, symptomatic adverse radiation effects (AREs), and surgical complication rate graded according to Common Terminology Criteria for Adverse Events version 5.0.

RESULTS

Between 2016 and 2020, 36 patients received 40 consecutive cesium-131 implants for 42 recurrent brain tumors and received imaging follow-up for a median (interquartile range [IQR]) of 17.0 (12.7-25.9) months. Twenty patients (55.6%) with 22 implants were treated for recurrent brain metastasis, 12 patients (33.3%) with 16 implants were treated for recurrent atypical (n = 7) or anaplastic (n = 5) meningioma, and 4 patients (11.1%) were treated for other recurrent primary brain neoplasms. All except 1 tumor (97.6%) had received prior radiotherapy, including 20 (47.6%) that underwent 2 or more prior radiotherapy treatments and 23 (54.8%) that underwent prior resection. The median (IQR) tumor size was 3.0 (2.3-3.7) cm, and 17 lesions (40.5%) had radiographic evidence of ARE prior to salvage therapy. Actuarial 1-year local/locoregional/intracranial control rates for the whole cohort and patients with metastases and meningiomas were 91.6%/83.4%/47.9%, 88.8%/84.4%/45.4%, and 100%/83.9%/46.4%, respectively. No cases of local recurrence of any histology (0 of 27) occurred after gross-total resection (p = 0.012, log-rank test). The 1-year OS rates for the whole cohort and patients with metastases and meningiomas were 82.7%, 79.1%, and 91.7%, respectively, and the median (IQR) survival of all patients was 26.7 (15.6-36.4) months. Seven patients (19.4%) experienced neurological death from progressive intracranial disease (7 of 14 total deaths [50%]), 5 (13.9%) of whom died of leptomeningeal disease. Symptomatic AREs were observed in 9.5% of resection cavities (n = 4), of which 1 (2.4%) was grade 3 in severity. The surgical complication rate was 16.7% (n = 7); 4 (9.5%) of these patients had grade 3 or higher complications, including 1 patient (2.4%) who died perioperatively.

CONCLUSIONS

Cesium-131 brachytherapy resulted in good local control and acceptable rates of symptomatic AREs and surgical complications in this heavily pretreated cohort, and it may be a reasonable salvage adjuvant treatment for this patient population.

MMAP-10 ADVERSE RADIATION EFFECT AFTER STEREOTACTIC RADIOSURGERY AND IMMUNOTHERAPY/TARGETED THERAPY FOR MELANOMA BRAIN METASTASES

BACKGROUND

Safety of immunotherapy (IO) and targeted therapy (TT) with stereotactic radiosurgery (SRS) in melanoma brain metastases (MBM) treatment remains incompletely understood. We aim to identify whether timing of IO/TT in relation to SRS impacts rates of adverse radiation effect (ARE) in MBM.

METHODS

Retrospective review of patients with MBM treated with SRS and IO/TT within three months prior and one year after SRS, from 2011-2021 at a single institution with at least two months MRI follow-up, identified 108 patients with 939 unique MBM meeting criteria. ARE was confirmed on independent imaging review. Concurrent IO/TT was defined as receiving IO/TT within 4 weeks before or after SRS. Data analysis was performed with the univariate cox proportional hazard model and Kaplan-Meier method.

RESULTS

Median radiographic follow-up from time of SRS was 16months. IO/TT was initiated prior to SRS for 681 (72.5%) metastases and after SRS for 258 (27.5%) metastases. 837 (89.1%) metastases received concurrent IO/TT. Most common IO agents were ipilimumab (n=416), nivolumab (n=448), and pembrolizumab (n=203). Most common TT agents were dabrafenib (n=548), trametinib (n=540), and vemurafenib (n=81). 2-year local progression-free survival (PFS), distant intracranial PFS, and overall survival were 94.1%, 33.3%, and 55.2%, respectively. 55 (5.9%) metastases in 33 (30.6%) patients experienced ARE. Median time to ARE was 5mo (IQR 4-9mo). Of those who experienced ARE, 22 (66.7%) patients were symptomatic and treated with steroids; 12 (36.4%) patients underwent surgical intervention. ARE rates were not impacted by concurrent vs nonconcurrent IO/TT (5.5% vs 4.9%, p=0.34) nor IO/TT initiation pre vs post SRS (6.0% vs 5.4%, p=0.61).

CONCLUSION

IO/TT in conjunction with SRS resulted in low ARE rates as compared to historical controls in the pre-IO/TT era. Timing of IO/TT in relation to SRS may not significantly impact ARE rates in MBM treatment.

Recurrent Radiation-Induced Cavernous Malformation After Gamma Knife Stereotactic Radiosurgery for Brain Metastasis

Cavernous malformations are a rare complication of radiation therapy reported most commonly as a late complication after cranial irradiation for pediatric malignancies. However, cavernous malformations after stereotactic radiosurgery in adult patients are not well characterized. We present a case of a 67-year-old female with metastatic breast cancer who received Gamma Knife stereotactic radiosurgery for brain metastases and developed a cavernous malformation at the site of a treated metastasis 30 months after treatment. She underwent resection and did well until 55 months later, when she developed symptomatic recurrence of cavernous malformation without evidence of tumor recurrence, requiring repeat resection. This represents the first reported case of radiation-induced cavernous malformation treated with stereotactic radiosurgery for brain metastases, who later developed a recurrence of the cavernous malformation. As patients with brain metastases are living longer and are increasingly treated with stereotactic radiosurgery, awareness of cavernous malformation as a potential complication and the risk of recurrence is critical to ensure appropriate diagnosis and management.

Long-Term Report of a Comprehensive Molecular and Genomic Analysis in NRG Oncology/RTOG 0424: A Phase II Study of Radiation and Temozolomide in High-Risk Grade II Glioma

PURPOSE

This study sought to determine the prognostic significance of the WHO-defined glioma molecular subgroups along with additional alterations, including MGMT promoter methylation and mutations in ATRX, CIC, FUBP1, TERT, and TP53, in NRG/RTOG 0424 using long-term follow-up data.

METHODS

Mutations were determined using an Ion Torrent sequencing panel. 1p/19q co-deletion and MGMT promoter methylation were determined by Affymetrix OncoScan and Illumina 450K arrays. Progression-free survival (PFS) and overall survival (OS) were estimated using the Kaplan-Meier method and tested using the log-rank test. Hazard ratios were calculated using the Cox proportional hazard model. Multivariable analyses (MVAs) included patient pretreatment characteristics.

RESULTS

We obtained complete molecular data to categorize 80/129 eligible patients within the WHO subgroups. Of these, 26 (32.5%) were IDHmutant/co-deleted, 28 (35%) were IDHmutant/non-co-deleted, and 26 (32.5%) were IDHwild-type. Upon single-marker MVA, both IDHmutant subgroups were associated with significantly better OS and PFS (P values < .001), compared with the IDHwild-type subgroup. MGMT promoter methylation was obtained on 76 patients, where 58 (76%) were methylated and 18 (24%) were unmethylated. Single-marker MVAs demonstrated that MGMT promoter methylation was statistically significant for OS (P value < .001) and PFS (P value = .003). In a multimarker MVA, one WHO subgroup comparison (IDHmutant/co-deleted v IDHwild-type) was significant for OS (P value = .045), whereas MGMT methylation did not retain significance.

CONCLUSION

This study reports the long-term prognostic effect of the WHO molecular subgroups, MGMT promoter methylation, and other mutations in NRG/RTOG 0424. These results demonstrate that the WHO molecular classification and MGMT both serve as strong prognostic indicators, but that MGMT does not appear to add statistically significant prognostic value to the WHO subgrouping, above and beyond IDH and 1p/19q status.

Adverse radiation effects in volume-staged radiosurgery for large arteriovenous malformations: a multiinstitutional study

OBJECTIVE

The optimal treatment paradigm for large arteriovenous malformations (AVMs) is controversial. One approach is volume-staged stereotactic radiosurgery (VS-SRS). The authors previously reported efficacy of VS-SRS for large AVMs in a multiinstitutional cohort; here they focus on risk of symptomatic adverse radiation effects (AREs).

METHODS

This is a multicentered retrospective review of patients treated with a planned prospective volume staging approach to stereotactically treat the entire nidus of an AVM, with volume stages separated by intervals of 3-6 months. A total of 9 radiosurgical centers treated 257 patients with VS-SRS between 1991 and 2016. The authors evaluated permanent, transient, and total ARE events that were symptomatic.

RESULTS

Patients received 2-4 total volume stages. The median age was 33 years at the time of the first SRS volume stage, and the median follow-up was 5.7 years after VS-SRS. The median total AVM nidus volume was 23.25 cm3 (range 7.7-94.4 cm3), with a median margin dose per stage of 17 Gy (range 12-20 Gy). A total of 64 patients (25%) experienced an ARE, of which 19 were permanent. Rather than volume, maximal linear dimension in the Z (craniocaudal) dimension was associated with toxicity; a threshold length of 3.28 cm was associated with an ARE, with a 72.5% sensitivity and a 58.3% specificity. In addition, parietal lobe involvement for superficial lesions and temporal lobe involvement for deep lesions were associated with an ARE.

CONCLUSIONS

Size remains the dominant predictor of toxicity following SRS, but overall rates of AREs were lower than anticipated based on baseline features, suggesting that dose and size were relatively dissociated through volume staging. Further techniques need to be assessed to optimize outcomes.

Abstract PO-073: Mutational status and clinical outcomes following systemic therapy and focal radiation for melanoma brain metastases

Brain metastases are the most common intracranial neoplasm yet clinical outcomes remain poor. The purpose of this study was to evaluate the efficacy of multimodal therapy comprising surgery followed by focal radiation, and/or systemic therapy and elucidate clinically significant biomarkers for resected melanoma brain metastases. Forty consecutive patients with newly diagnosed melanoma brain metastases who underwent surgical resection and targeted mutational analysis at UCSF between 2011 and 2020 were identified. Demographic, clinical, and outcome data were extracted from the medical record and institutional cancer registry. Surgical cavity local recurrence free survival (LRFS), intracranial progression free survival (PFS) and overall survival (OS) were estimated using the Kaplan-Meier method. The median age of patients in this cohort was 58 years (range: 27-75 years) with median MRI follow up of 13.15 months. Twenty patients (50%) were treated with concurrent stereotactic radiation (1-5 fractions) and systemic therapy while 16 patients (40%) were treated with systemic therapy only. Mutational testing demonstrated the most common pathogenic variant was BRAF V600E, found in 16 patients (40%), while the remaining 24 patients (60%) did not harbor this mutation. Microsatellite instability (MSI) estimation was available for 8 patients (20%), all of which were found to be MSI low (&lt;2%). Median LRFS was significantly improved with combined focal radiation and systemic therapy compared to systemic therapy alone (NR versus 15 months, p=0.01; log-rank test). Patients harboring BRAF V600E mutations had worse intracranial PFS compared to those without V600E mutation (4 months versus 12 months, p=0.048; log-rank test), as well as a trend toward worse OS (NR vs 13 months, p=0.09; log-rank test). Systemic agent choice was heterogeneous, with 24 patients (60%) treated with immunotherapy alone, 12 patients (30%) treated with dual BRAF/MEK inhibitor therapy alone, and the remainder treated with mixed regimens (10%) with no differences in efficacy or toxicity between these subgroups. Our results suggest combined focal radiation and systemic therapy is effective for melanoma brain metastases. Moreover, specific molecular alterations such as BRAF V600E mutation are associated with poorer outcomes, and all brain metastases in our cohort were MSI low. Limitations of our study include its retrospective nature, limited sample size, and heterogeneity of systemic regimens, and future prospective validation and multiplatform genomic analysis are needed to build on our findings.

Citation Format: Harish N. Vasudevan, Matthew S. Susko, Lijun Ma, Jean L. Nakamura, David R. Raleigh, Lauren Boreta, Shannon Fogh, Philip V. Theodosopoulos, Michael W. McDermott, Katy K. Tsai, Penny K. Sneed, Steve E. Braunstein. Mutational status and clinical outcomes following systemic therapy and focal radiation for melanoma brain metastases [abstract]. In: Proceedings of the AACR Virtual Special Conference on Radiation Science and Medicine; 2021 Mar 2-3. Philadelphia (PA): AACR; Clin Cancer Res 2021;27(8_Suppl):Abstract nr PO-073.

A Prognostic Gene-Expression Signature and Risk Score for Meningioma Recurrence After Resection

BACKGROUND

Prognostic markers for meningioma are needed to risk-stratify patients and guide postoperative surveillance and adjuvant therapy.

OBJECTIVE

To identify a prognostic gene signature for meningioma recurrence and mortality after resection using targeted gene-expression analysis.

METHODS

Targeted gene-expression analysis was used to interrogate a discovery cohort of 96 meningiomas and an independent validation cohort of 56 meningiomas with comprehensive clinical follow-up data from separate institutions. Bioinformatic analysis was used to identify prognostic genes and generate a gene-signature risk score between 0 and 1 for local recurrence.

RESULTS

We identified a 36-gene signature of meningioma recurrence after resection that achieved an area under the curve of 0.86 in identifying tumors at risk for adverse clinical outcomes. The gene-signature risk score compared favorably to World Health Organization (WHO) grade in stratifying cases by local freedom from recurrence (LFFR, P < .001 vs .09, log-rank test), shorter time to failure (TTF, F-test, P < .0001), and overall survival (OS, P < .0001 vs .07) and was independently associated with worse LFFR (relative risk [RR] 1.56, 95% CI 1.30-1.90) and OS (RR 1.32, 95% CI 1.07-1.64), after adjusting for clinical covariates. When tested on an independent validation cohort, the gene-signature risk score remained associated with shorter TTF (F-test, P = .002), compared favorably to WHO grade in stratifying cases by OS (P = .003 vs P = .10), and was significantly associated with worse OS (RR 1.86, 95% CI 1.19-2.88) on multivariate analysis.

CONCLUSION

The prognostic meningioma gene-expression signature and risk score presented may be useful for identifying patients at risk for recurrence.

EPCO-36. GENOMIC INSTABILITY AND TRANSCRIPTOMIC SIGNATURES UNDERLYING EPIGENETIC MENINGIOMA SUBGROUPS REVEALS MECHANISMS OF IMMUNE INFILTRATION AND THERAPEUTIC VULNERABILITIES

BACKGROUND

Meningioma treatments are limited due to incomplete understanding of meningioma biology. To address this, we performed multiplatform molecular profiling on 565 meningiomas with comprehensive clinical data to define genomic drivers and identify therapeutic vulnerabilities.

METHODS

DNA methylation profiling was performed on meningiomas from UCSF (n=200, discovery) and Hong Kong University (n=365, validation). Median follow-up was 5.6 years, and there were 388/142/35 WHO grade I/II/III meningiomas. Copy number variants (CNVs) were calculated for all meningiomas, and RNA sequencing was performed on UCSF meningiomas. Cell type deconvolution, metagenomics, CRISPR, and pharmacology were used for mechanistic and functional validation.

RESULTS

Unsupervised hierarchical clustering of differentially methylated DNA probes revealed that meningiomas were comprised of 3 epigenetic subgroups associated with good, intermediate, and poor outcomes, with representation from all WHO grades in each subgroup. Meningiomas from the subgroup with the best outcomes (52% WHO grade I) were distinguished by recurrent gain of Chr5. Meningiomas from the subgroup with intermediate outcomes (31% WHO grade II) were distinguished by genomic stability, enrichment of innate immune genes, and immune infiltration in the setting of endogenous retroviral gene re-expression, a mechanism of immune recruitment. The most aggressive subgroup of meningiomas (57% WHO grade III) was distinguished by genomic instability, including recurrent loss of Chr22q harboring NF2, and decreased immune infiltration. Consistently, NF2 suppression in primary meningioma cells derived from immunogenic meningiomas decreased expression of innate immune genes critical for immune recruitment, suggesting a novel immunostimulatory function of NF2. The most aggressive subgroup of meningiomas were further distinguished by activation of the mitogenic FOXM1 transcriptional program, and recurrent loss of Chr9p harboring CDKN2A/B, which rendered primary meningioma cells from this subgroup susceptible to CDK4/6 inhibitors.

CONCLUSIONS

Meningiomas are comprised of 3 epigenetic subgroups defined by genetic mechanisms driving immune infiltration in the tumor microenvironment and meningioma cell proliferation.

BIOM-52. A PROGNOSTIC GENE EXPRESSION RISK SCORE FOR MENINGIOMA

BACKGROUND

Clinical biomarkers for identifying patients at risk for recurrence after resection of meningioma are lacking and are needed for guiding adjuvant therapy. The aim of this study was to identify a prognostic gene expression signature for meningioma.

METHODS

Targeted gene expression analysis was performed on a discovery dataset of 96 meningiomas with suitable tissue identified from a retrospective institutional biorepository. Recurrence was dichotomized based on the median time to local recurrence (TTR). With median follow-up of 6.4 years, the discovery dataset was enriched for clinical endpoints of local recurrence (58%), mortality (42%), and disease-specific mortality (49% of deaths). A 266 gene expression panel was used to interrogate the discovery dataset, and a prognostic gene signature and risk score was generated using prediction analysis for microarrays (PAM) and elastic net regression. The risk score was validated using gene expression data (GSE58037) from 56 meningiomas resected at an independent institution (20% local recurrence, 18% mortality, median follow-up 5.4 years).

RESULTS

A 36-gene signature was identified achieving an AUC of 0.86 for TTR faster than the median in the discovery cohort. A risk score between 0 and 1 based on this signature was strongly associated with shorter TTR (F-test, P&lt; 0.0001), and on multivariate Cox regression (MVA), was independently associated with recurrence (RR 1.56 per 0.1 increase, 95% CI 1.30–1.90, P&lt; 0.0001) and mortality (RR 1.32 per 0.1 increase, 1.07–1.64, P=0.01) after adjusting for WHO grade, age, extent of resection, and sex. Similarly, in the validation dataset, the gene risk score was correlated with shorter TTR (P=0.002) and associated with mortality on MVA (RR 1.86 per 0.1 increase, 1.19–2.88, P=0.005) after adjustment for WHO grade.

CONCLUSIONS

The prognostic meningioma gene expression risk score presented here could be useful in identifying patients at higher risk of progression after resection.

Temporal Dynamics of Pseudoprogression After Gamma Knife Radiosurgery for Vestibular Schwannomas-A Retrospective Volumetric Study

BACKGROUND

The optimal observation interval after the radiosurgical treatment of a sporadic vestibular schwannoma, prior to salvage intervention, is unknown.

OBJECTIVE

To determine an optimal postradiosurgical treatment interval for differentiating between pseudoprogression and true tumor growth by analyzing serial volumetric data.

METHODS

This single-institution retrospective study included all sporadic vestibular schwannomas treated with Gamma Knife radiosurgery (Eketa AB, Stockholm, Sweden; 12-13 Gy) from 2002 to 2014. Volumetric analysis was performed on all available pre- and posttreatment magnetic resonance imaging scans. Tumors were classified as "stable/decreasing," "transient enlargement", or "persistent growth" after treatment, based on incrementally increasing follow-up durations.

RESULTS

A total of 118 patients included in the study had a median treatment tumor volume of 0.74 cm3 (interquartile range [IQR] = 0.34-1.77 cm3) and a median follow-up of 4.1 yr (IQR = 2.6-6.0 yr). Transient tumor enlargement was observed in 44% of patients, beginning at a median of 1 yr (IQR = 0.6-1.4 yr) posttreatment, with 90% reaching peak volume within 3.5 yr, posttreatment. Volumetric enlargement resolved at a median of 2.4 yr (IQR 1.9-3.6 yr), with 90% of cases resolved at 6.9 yr. Increasing follow-up revealed that many of the tumors initially enlarging 1 to 3 yr after stereotactic radiosurgery ultimately begin to shrink on longer follow-up (45% by 4 yr, 77% by 6 yr).

CONCLUSION

Tumor enlargement within ∼3.5 yr of treatment should not be used as a sole criterion for salvage treatment. Patient symptoms and tumor size must be considered, and giving tumors a chance to regress before opting for salvage treatment may be worthwhile.

Dose response and architecture in volume staged radiosurgery for large arteriovenous malformations: A multi-institutional study

BACKGROUND

Optimal treatment paradigm for large arteriovenous malformations (AVMs) is controversial. Volume-staged stereotactic radiosurgery (VS-SRS) provides an effective option for these high-risk lesions, but optimizing treatment for these recalcitrant and rare lesions has proven difficult.

METHODS

This is a multi-centered retrospective review of patients treated with a planned prospective volume staging approach to stereotactically treat the entire nidus of an AVM with volume stages separated by intervals of 3-6 months. A total of 9 radiosurgical centers treated 257 patients with VS-SRS between 1991 and 2016. We evaluated near complete response (nCR), obliteration, cure, and overall survival.

RESULTS

With a median age of 33 years old at the time of first SRS volume stage, patients received 2-4 total volume stages and a median follow up of 5.7 years after VS-SRS. The median total AVM nidus volume was 23.25 cc (range: 7.7-94.4 cc) with a median margin dose per stage of 17 Gy (range: 12-20 Gy). Total AVM volume, margin dose per stage, compact nidus, lack of prior embolization, and lack of thalamic location involvement were all associated with improved outcomes. Dose >/= 17.5 Gy was strongly associated with improved rates of nCR, obliteration, and cure. With dose >/= 17.5 Gy, 5- and 10-year cure rates were 33.7% and 76.8% in evaluable patients compared to 23.7% and 34.7% of patients with 17 Gy and 6.4% and 20.6% with <17 Gy per volume-stage (p = 0.004). Obliteration rates in diffuse nidus architecture with <17 Gy were particularly poor with none achieving obliteration compared to 32.3% with doses >/= 17 Gy at 5 years (p = 0.007). Comparatively, lesions with a compact nidus architecture exhibited obliteration rates at 5 years were 10.7% vs 9.3% vs 26.6% for dose >17 Gy vs 17 Gy vs >/=17.5 Gy.

CONCLUSION

VS-SRS is an option for upfront treatment of large AVMs. Higher dose was associated with improved rates of nCR, obliteration, and cure suggesting that larger volumetric responses may facilitate salvage therapy and optimize the chance for cure.

Stereotactic Radiosurgery to More Than 10 Brain Metastases: Evidence to Support the Role of Radiosurgery for Ideal Hippocampal Sparing in the Treatment of Multiple Brain Metastases

BACKGROUND

Brain metastases are a common occurrence, with literature supporting the treatment of a limited number of brain metastases with stereotactic radiosurgery (SRS), as opposed to whole brain radiotherapy (WBRT). Less well understood is the role of SRS in patients with ≥10 brain metastases.

METHODS

Patients treated with SRS to ≥10 brain metastases without concurrent WBRT between March 1999 and December 2016 were reviewed. Analysis was performed for overall survival, treated lesion freedom from progression (FFP), freedom from new metastases (FFNMs), and adverse radiation effect. Hippocampal volumes were retrospectively generated in patients treated with up-front SRS for evaluation of dose volume metrics.

RESULTS

A total of 143 patients were identified with 75 patients having up-front SRS and 68 patients being treated as salvage therapy after prior WBRT. The median number of lesions per patient was 13 (interquartile range [IQR], 11-17). Median total volume of treatment was 4.1 cm³ (IQR, 2.0-9.9 cm³). The median 12-month FFP for up-front and salvage treatment was 96.8% (95% confidence interval [CI], 95.5-98.1) and 83.6% (95% CI, 79.9-87.5), respectively (P < 0.001). Twelve-month FFNMs for up-front and salvage SRS was 18.8% (95% CI, 10.9-32.3) versus 19.2% (95% CI, 9.7-37.8), respectively (P = 0.90). The mean hippocampal dose was 150 cGy (IQR, 100-202 cGy).

CONCLUSIONS

Excellent rates of local control can be achieved when treating patients with >10 intracranial metastases either in the up-front or salvage setting. Hippocampal sparing is readily achievable with expected high rates of new metastatic lesions in treated patients.

Comprehensive Molecular Profiling Identifies FOXM1 as a Key Transcription Factor for Meningioma Proliferation

Meningioma is the most common primary intracranial tumor, but the molecular drivers of aggressive meningioma are incompletely understood. Using 280 human meningioma samples and RNA sequencing, immunohistochemistry, whole-exome sequencing, DNA methylation arrays, and targeted gene expression profiling, we comprehensively define the molecular profile of aggressive meningioma. Transcriptomic analyses identify FOXM1 as a key transcription factor for meningioma proliferation and a marker of poor clinical outcomes. Consistently, we discover genomic and epigenomic factors associated with FOXM1 activation in aggressive meningiomas. Finally, we define a FOXM1/Wnt signaling axis in meningioma that is associated with a mitotic gene expression program, poor clinical outcomes, and proliferation of primary meningioma cells. In summary, we find that multiple molecular mechanisms converge on a FOXM1/Wnt signaling axis in aggressive meningioma.

Using multiplatform molecular profiling, Vasudevan et al. comprehensively define the molecular profile of aggressive meningioma. They identify genomic, epigenomic, and transcriptomic mechanisms that converge on a FOXM1/Wnt signaling axis in aggressive meningioma that is associated with meningioma cell proliferation and is a marker of poor clinical outcomes across molecular subgroups.

Integrated models incorporating radiologic and radiomic features predict meningioma grade, local failure, and overall survival

Background

We investigated prognostic models based on clinical, radiologic, and radiomic feature to preoperatively identify meningiomas at risk for poor outcomes.

Methods

Retrospective review was performed for 303 patients who underwent resection of 314 meningiomas (57% World Health Organization grade I, 35% grade II, and 8% grade III) at two independent institutions, which comprised primary and external datasets. For each patient in the primary dataset, 16 radiologic and 172 radiomic features were extracted from preoperative magnetic resonance images, and prognostic features for grade, local failure (LF) or overall survival (OS) were identified using the Kaplan–Meier method, log-rank tests and recursive partitioning analysis. Regressions and random forests were used to generate and test prognostic models, which were validated using the external dataset.

Results

Multivariate analysis revealed that apparent diffusion coefficient hypointensity (HR 5.56, 95% CI 2.01–16.7, P = .002) was associated with high grade meningioma, and low sphericity was associated both with increased LF (HR 2.0, 95% CI 1.1–3.5, P = .02) and worse OS (HR 2.94, 95% CI 1.47–5.56, P = .002). Both radiologic and radiomic predictors of adverse meningioma outcomes were significantly associated with molecular markers of aggressive meningioma biology, such as somatic mutation burden, DNA methylation status, and FOXM1 expression. Integrated prognostic models combining clinical, radiologic, and radiomic features demonstrated improved accuracy for meningioma grade, LF, and OS (area under the curve 0.78, 0.75, and 0.78, respectively) compared to models based on clinical features alone.

Conclusions

Preoperative radiologic and radiomic features such as apparent diffusion coefficient and sphericity can predict tumor grade, LF, and OS in patients with meningioma.

Direct and indirect costs associated with stereotactic radiosurgery or open surgery for medial temporal lobe epilepsy: Results from the ROSE trial

OBJECTIVE

To determine whether a less-invasive approach to surgery for medically refractory temporal lobe epilepsy is associated with lower health care costs and costs of lost productivity over time, compared to open surgery.

METHODS

We compared direct medical costs and indirect productivity costs associated with treatment with stereotactic radiosurgery (SRS) or anterior temporal lobectomy (ATL) in the ROSE (Radiosurgery or Open Surgery for Epilepsy) trial. Health care use was abstracted from hospital bills, the study database, and diaries in which participants recorded health care use and time lost from work while seeking care. Costs of use were calculated using a Medicare costing approach used in a prior study of the costs of ATL. The power of many analyses was limited by the sample size and data skewing.

RESULTS

Combined treatment and follow-up costs (in thousands of US dollars) did not differ between SRS (n = 20, mean = $76.6, 95% confidence interval [CI] = 50.7-115.6) and ATL (n = 18, mean = $79.0, 95% CI = 60.09-103.8). Indirect costs also did not differ. More ATL than SRS participants were free of consciousness-impairing seizures in each year of follow-up (all P < 0.05). Costs declined following ATL (P = 0.005). Costs tended to increase over the first 18 months following SRS (P = 0.17) and declined thereafter (P = 0.06). This mostly reflected hospitalizations for SRS-related adverse events in the second year of follow-up.

SIGNIFICANCE

Lower initial costs of SRS for medial temporal lobe epilepsy were largely offset by hospitalization costs related to adverse events later in the course of follow-up. Future studies of less-invasive alternatives to ATL will need to assess adverse events and major costs systematically and prospectively to understand the economic implications of adopting these technologies.