Sener, Uğur

Abstract Cerebrospinal fluid (CSF) has emerged as a valuable liquid biopsy source for glioma biomarker discovery and validation. CSF produced within the ventricles circulates through the subarachnoid space, where the composition of glioma-derived analytes is influenced by the proximity and anatomical location of sampling relative to tumor, in addition to underlying tumor biology. The substantial gradients observed between lumbar and intracranial CSF compartments for tumor-derived analytes underscore the importance of sampling site selection. Moreover, radiographic features, such as tumor-CSF contact and blood-brain barrier disruption, are critical covariates that may affect biomarker detection and the abundance of plasma-derived analytes in CSF, respectively. Longitudinal intracranial CSF sampling, enabled by access devices like Ommaya reservoirs, may offer a window into treatment response and disease progression, though variability in analyte yield, sample volumes, and the dynamic effects of surgical resection pose challenges. This review critically evaluates the anatomic, radiographic, and longitudinal factors, or “time-space continuum,” that impact glioma CSF biomarker abundance. Practical considerations for longitudinal CSF biobanking, including access device placement and collection, are also reviewed. Key takeaways and recommendations for CSF glioma biomarker discovery and validation are provided as a “hitchhiker’s guide” based on our collective experience, along with resources for investigators aiming to develop CSF biobanking at their institutions.

Abstract Purpose: Current methods for glioma response assessment are limited. This study aimed to assess the technical and clinical feasibility of molecular profiling using longitudinal intracranial cerebrospinal fluid (CSF) from patients with gliomas. Experimental Design: Adults with gliomas underwent longitudinal intracranial CSF collection via Ommaya reservoirs or ventriculoperitoneal shunts. Cell-free DNA (cfDNA) was extracted and analyzed using PredicineCARE for cancer variant profiling and/or PredicineSCORE for low-pass whole-genome sequencing. Results: Five patients (two females and three males; median age, 40 years; range, 32–64 years) underwent longitudinal intracranial CSF collection via Ommaya reservoirs (n = 4) or ventriculoperitoneal shunts (n = 1). In total, 47 CSF samples were obtained (median volume, 4.00 mL; 0.5–5 mL). Forty-one samples (87.2%) yielded sufficient cfDNA for testing. Patient-specific tumor-associated variant allelic frequencies (VAF), and thus tumor fraction, decreased in pre- versus postchemoradiation samples, including through pseudoprogression. These also increased with radiographic progression in three patients, although identifying the time of definitive disease progression from MRIs was a significant limitation. In two patients with isocitrate dehydrogenase (IDH)–mutant gliomas, decreasing IDH1 VAF after resection and chemoradiation correlated with decreased CSF D-2-hydroxyglutarate levels (0.64× and 0.62×, respectively, for the first patient and 0.01× and 0.07× for the other patient), although D-2-hydroxyglutarate and IDH1 VAF were not concordant in one patient thereafter. Moreover, the copy-number burden decreased below the limit of quantification during treatment and increased above the limit at progression. Conclusions: Longitudinal intracranial CSF cfDNA can be obtained in patients with gliomas during their disease course. However, before deploying this technique, numerous questions and challenges should be answered.

Abstract BACKGROUND Central nervous system (CNS) tumors are frequently characterized by physical disabilities, and treatment is often associated with side effects, as well as financial toxicity and loss of income owing to disease-related neurological deficits. Treatment at centers with specialized neuro-oncology care is associated with an overall survival benefit. However, access to such centers can be limited for many patients. Telehealth services represent an option for improving access to specialized care. During the COVID-19 pandemic public health emergency (PHE), regulatory and reimbursement changes provided patients improved access to neuro-oncology by telehealth. METHODS We retrospectively analyzed our institutional utilization of telehealth visits in the neuro-oncology vs solid tumor oncology practice after the COVID-19 pandemic. RESULTS Between July 2020 and April 2021, telehealth represented 24.1% of all neuro-oncology visits compared to 13.3% for all solid tumor groups. Between May 2021 and April 2023, telehealth visits remained frequent in neuro-oncology compared to solid tumor groups (34.6% vs 15.2%). Utilization rates declined across the practice in the year following expiration of the COVID-19 PHE in May 2023, though remained high for neuro-oncology at 34.1% vs 15.2% for solid tumor groups. Overall, telehealth visit utilization for neuro-oncology has remained more than double that of the oncology practice as a whole. CONCLUSIONS The striking difference between telehealth visit utilization in neuro-oncology compared with general medical oncology indicates that patients with CNS tumors, and those that provide care for these patients, have come to depend on this mode of care delivery. Even after expiration of the COVID-19 PHE, telehealth use remains high in neuro-oncology at our institution. Prospective evaluation to determine the safety of and clinical outcomes associated with telehealth visits for individuals with CNS tumors are critically needed. Such data may promote regulatory and reimbursement reform enabling broader adoption, service sustainability, and improved access to specialized care.

Abstract BACKGROUND Pineocytoma is a rare pineal parenchymal WHO grade 1 tumor, typically well-managed with surgical resection alone. With gross total resection (GTR), 91% 1-year and 84% 5-year survival rates have been reported. Recurrent pineocytoma is rare and optimal management in that setting is unknown, in part owing to the rarity of the condition. METHODS We report an atypical course of pineocytoma in a 58-year-old male involving metastatic disease. RESULTS A pineal mass was identified upon MRI of the brain obtained for vision changes. Patient underwent GTR, pathology was consistent with pineocytoma, WHO grade 1. Ki-67 labeling index was low at 1-2%. Despite low-grade pathology, two years later, surveillance imaging demonstrated recurrence in the pineal region and a second lesion in the right thalamus. The patient underwent gamma knife surgery (GKRS) to both lesions. Three years later, he developed three new lesions in the right cerebellum and again underwent GKRS. Subsequent surveillance imaging identified new lesions in the right cerebellum and along ventricular walls, treated with further GKRS. Nine years after initial diagnosis, focal nodular leptomeningeal metastases were discovered, along with progression at the primary tumor site. Patient was treated with GKRS to the nodular deposits followed by pembrolizumab. Further disease progression as noted despite immunotherapy. Patient was treated with 6 cycles of temozolomide chemotherapy and at further progression 3 cycles of lomustine. Upon additional progression, further radiation therapy was administered with bevacizumab to reduce risk of radiation necrosis. Patient remains on surveillance 13 years after initial diagnosis with visual changes and mild headache representing only clinical issues. CONCLUSIONS Although exceedingly rare, pineocytoma is capable of metastasizing to brain parenchyma and the leptomeninges, as demonstrated in our patient. However, our case demonstrates prolonged survival is possible even in the setting of relentlessly progressive metastatic disease with utilization of multimodality treatment.

Abstract BACKGROUND Meningiomas are the most common primary intracranial tumors, typically managed with surgical resection and/or radiation therapy. Systemic therapy options are limited and reserved for cases refractory to conventional interventions. Cyclin dependent kinase (CDK) proteins are key cell cycle regulators. CDK inhibitors are clinically available, approved for treatment of breast cancer and in clinical trials for meningioma. METHODS We present a case where a patient with incidentally-discovered intracranial meningioma undergoing CDK inhibitor therapy with ribociclib for breast cancer experienced a radiographic response. RESULTS A 73-year-old female was diagnosed with estrogen receptor (ER) positive, progesterone receptor (PR) positive, HER2 negative metastatic invasive ductal carcinoma of the breast. She was treated with estrogen receptor antagonist fulvestrant and CDK 4/6 inhibitor ribociclib. MRI of the brain performed for disease staging demonstrated an extraaxial, dural-based, homogenously enhancing mass along the left posterior petrous ridge consistent with a meningioma. Two-month interval scan demonstrated a marginal decrease in size of the mass (15.6x18.3 mm to 15.4x17.5 mm). Systemic disease related to breast cancer concurrently improved. Two years later, with ongoing fulvestrant and ribociclib therapy, a repeat MRI brain demonstrated further decrease in size of the meningioma (13.4x16.8 mm). CONCLUSIONS Hormonally-directed therapies previously demonstrated limited benefit for meningiomas despite PR/ER positivity reported for these tumors. However, CDK 4/6 inhibitors abemaciclib and ribociclib have demonstrated activity in treatment of recurrent grade 2/3 meningiomas. The radiographic response noted in our case suggests there may be a role for systemic therapy even in treatment-naive cases that may not be amenable to surgical resection or radiation therapy.

Abstract INTRODUCTION Lymphopenia attributed to postoperative chemoradiotherapy (CRT) can accelerate tumor recurrence and contribute to poor prognosis in GBM. We hypothesize that short course (1-2 weeks) CRT can mitigate lymphopenia compared to standard course and may provide immune benefits for future combination therapy. METHODS GBM patients were randomized on a multi-site phase II study comparing short course (35Gy/5Fx or 40Gy/10Fx depending on target volume) (Arm A) versus standard dose fractionation (60Gy/30Fx or 40Gy/15Fx, Arm B). All patients received concurrent and adjuvant temozolomide (TMZ). This unplanned interim analysis evaluates changes of absolute lymphocyte count (ALC), CD4 and CD8 prospectively at 3-timepoints: baseline (prior to CRT), end of CRT, and 1-month post-CRT. RESULTS To date, 72 patients enrolled (34 Arm A, 38 Arm B). Median age 66 (35-86), ECOG 0-2. Patients characteristics as followed in Arm A vs. Arm B, respectively: female 47% vs. 42%, MGMT promotor methylated 31% vs. 34%, steroid use 46% vs. 45%, ALC 1310 cells/mm3 (330 –9730) vs. 1480 (750 –7750), CD4 531 cells/mm3 (86 –1368) vs. 662 (318 –1671), and CD8 151 cells/mm3 (56 –940) vs. 272 (68 –875). Lymphocytes data were collected in 49 patients (21 Arm A, 28 Arm B). There were signficantly fewer reductions of ALC, CD4 and CD8 in Arm A. Median ALC changes were 95% and 99% of baseline (Arm A) vs 52% and 61% of baseline (Arm B) at the end of CRT and 1-month post-CRT, respectively (p<0.01). Median CD4 changes 93% and 96% of baseline (Arm A) vs 51% and 49% (Arm B), and median CD8 changes 97% and 98% of baseline (Arm A) vs 57% and 71% (Arm B) at the end of CRT and 1-month post-CRT, respectively (p<0.05). CONCLUSIONS This interim analysis suggests that short course RT could reduce treatment-related lymphopenia and immune suppression compared to standard RT, thus could be potentially beneficial to combine with immunotherapy.

Abstract BACKGROUND Lynch syndrome is caused by pathogenic germline variants in the DNA mismatch repair (MMR) genes, predisposing individuals to malignancies, including glioblastoma (GBM). MMR-deficient tumors are resistant to monofunctional alkylators such as temozolomide but not to bifunctional alkylators such as the nitrosourea lomustine. Anti-programmed cell death protein 1 (PD1) immune checkpoint inhibitor (ICI) pembrolizumab represents another treatment option, which is approved by the United States Food and Drug Administration (FDA) for the treatment of mismatch repair deficient cancers. METHODS We present a patient with multifocal GBM and Lynch syndrome who experienced rapid progression following standard-of-care chemoradiation, followed by durable responses to lomustine and then to pembrolizumab. RESULTS A 58-year-old man with Lynch syndrome (MSH2 mutation) and prior history of colon cancer presented with seizures. Magnetic resonance imaging (MRI) brain identified right frontal and left parietal masses. Right frontal tumor was resected; pathology was consistent with GBM, IDH wildtype, MGMT-unmethylated. Both lesions were treated with radiation therapy (60 Gy, 30 fractions) with concurrent and adjuvant temozolomide. After two cycles of adjuvant temozolomide, his left parietal tumor progressed and was subtotally resected, followed by four cycles of lomustine (stopped due to myelotoxicity). He remained progression-free for 15 months. Surveillance MRI identified new enhancement involving the left frontal lobe, left periventricular white matter, and right internal auditory canal, concerning for leptomeningeal dissemination. MRI spine identified no additional lesions. Cerebrospinal fluid cytology was negative for tumor cells on two occasions. Patient was treated with pembrolizumab. He remains on treatment with stable disease four months after ICI initiation and 31 months after GBM diagnosis. CONCLUSIONS Patients with MMR-deficient GBM resist standard chemoradiation. Alternatives such as nitrosourea or ICI therapy may achieve durable responses. While data is insufficient to administer these agents as upfront therapy in this specific setting, both should be considered as options for recurrent disease.

Abstract Improved response assessment methods are needed for patients with gliomas. Intracranial cerebrospinal fluid (CSF) is longitudinally accessible and provides an abundance source of candidate biomarkers, such as cell-free DNA (cfDNA), for disease monitoring. To evaluate the clinical feasibility of molecular profiling from longitudinal intracranial CSF, CSF was acquired from patients with CSF access devices, including Ommaya reservoirs and ventriculoperitoneal shunts. cfDNA was extracted and analyzed via PredicineCARE (Next Generation sequencing) or PredicineSCORE (low pass whole genome sequencing). Five patients (2 females, 3 males; median age: 40 years, range 32-64 years) underwent longitudinal intracranial CSF collection via Ommaya reservoirs (n=4) or VP shunt (n=1). In total, forty-eight CSF samples were obtained (median volume: 4.00 mL; 0.5-5 mL), with 39 samples (81.3%) yielding sufficient cfDNA for variant profiling. Our initial findings suggest that tumor fraction increased by 6.28x, 2.87x, and 8.31x with radiographic progression in three patients. Tumor fraction decreased by 0.08x and 0.04x in two patients with paired immediate pre-versus-post chemoradiation samples. Despite ongoing pseudoprogression in one patient, tumor fraction decreased to unmeasurable levels from a post-resection baseline of 0.26. Patient-specific tumor-associated variant allelic frequencies (VAFs), including TP53, PTEN, TERT, and CDKN2A/B, decreased within individual patients after resection and chemoradiation. In two patients with isocitrate dehydrogenase (IDH) mutant gliomas, decreasing IDH1 VAF after resection and chemoradiation correlated with decreased CSF D-2-hydroxyglutarate (D-2-HG) levels (0.64x and 0.62x, respectively, for the first patient, and 0.01x and 0.07x for the other patient). Both CSF IDH1 VAF and CSF D-2-HG increased a patient who had radiographic progression (2.56x and 9.21x, respectively). Moreover, CNB decreased below the limit of quantification during treatment and increased above the limit at progression. In conclusion, longitudinal CSF cfDNA can feasibly be obtained via CSF access devices in patients with gliomas during their disease course toward evaluating candidate monitoring biomarkers.

Abstract While serial sampling of glioma tissue is rarely performed before recurrence, cerebrospinal fluid (CSF) can be acquired serially to evaluate candidate monitoring and pharmacodynamic biomarkers in patients with gliomas. However, the impact of key variables to consider in longitudinal CSF, including anatomical location and post-surgical changes, remains unknown. To that end, pre- versus post-resection intracranial CSF samples from patients with gliomas were obtained at early (1-16 days; n=20) or delayed (86-153 days; n=11) timepoints, as well as lumbar-versus-intracranial glioma CSF samples (n=14). Using aptamer-based proteomics, we identified significant differences in the glioma CSF proteome between lumbar, subarachnoid, and ventricular CSF. Indeed, intracranial CSF in paired lumbar/intracranial samples had nearly 1600 unique aptamers, regardless of which intracranial location was compared to the paired lumbar CSF, including in enrichment style analyses that evaluated the overlap between protein states. Importantly, resection had a significant, evolving longitudinal impact on the CSF proteome, with subsets of proteins associated with early versus delayed post-resection changes, many of which were enriched for inflammatory-related pathways. Interestingly, despite increased contamination from surgical debris, enrichment for plasma-associated proteins decreased with resection (FDR: 0.000), suggesting that a portion of the baseline glioma panel could be derived from plasma-originating analytes due to blood-brain barrier disruption. Despite these challenges, our data still revealed preliminary candidate monitoring biomarkers, such as brevican, that increased with progression (example patient: fold-change of 3.58x and 2.08x through lomustine and bevacizumab, respectively), but not pseudoprogression (Fold change less than 1.5). Serial intracranial CSF samples suggested the early potential for disease monitoring and evaluation of pharmacodynamic impact of targeted therapies, including bevacizumab and pembrolizumab. In conclusion, our available data to date suggest that the intracranial glioma CSF proteome provides an abundant and evolving source of candidate biomarkers to longitudinally discern the impact of resection and systemic treatments.

Abstract BACKGROUND Fatigue is among the most common symptoms managed by patients with cancer. Hypothalamic pituitary axis dysfunction has an established role in a subset of patients with fatigue. Our primary aim was to longitudinally assess the impact of hypothalamic radiation exposure to patient self-reported fatigue. METHODS We included a sample of patients who received radiation therapy treated at a single institution from 2014-2024. The PROMIS-10 questionnaire (“How would you rate your fatigue on average,” scale 1-5) was used in standard clinical practice, with measures from 6 time points over 2 years. We performed descriptive statistics. Linear mixed models were used to assess the impact of hypothalamic radiation dose on fatigue scores. Mixed models were controlled for gender, age, time, tumor category (CNS vs. non-CNS), and modality (photon vs. proton). Models were fit with random intercepts for each Patient ID. RESULTS 1092 patients (43% female) with a median age of 54 years (range: 18-92) were included. Most patients were treated for CNS cancer (76%), with about 50% each photon and proton. Median hypothalamus radiation dose was 1306 cGy (range: 0.01-6138). Mean baseline fatigue (2.4) increased after treatment (2.7) remaining elevated at 3- and 6-months post-treatment (2.6, 2.5), returning near baseline at 1- and 2-years post-treatment (2.4, 2.3). Higher radiation dose (Estimate (SE): 0.014 (0.006), p=0.0266) and CNS cancer treatment (0.11 (0.051), p=0.0319) were significant predictors of higher fatigue in the mixed model. Male patients (-0.16 (0.042), p=0.0001) and time (-0.003 (0.0016), p=0.0398) were associated with lower fatigue. Age and treatment modality were not significant predictors of fatigue. CONCLUSIONS We found that higher hypothalamic radiation dose was related to more self-reported fatigue, which peaked by 6 months. This effect was seen more prominently in female patients and those treated for CNS disease. Treatment modality and age did not influence fatigue scores.