Comparison of dynamic susceptibility contrast (DSC) using gadolinium and iron-based contrast agents in high-grade glioma at high-field MRI.

PURPOSE: To compare DSC-MRI using Gadolinium (GBCA) and Ferumoxytol (FBCA) in high-grade glioma at 3T and 7T MRI field strengths. We hypothesized that using FBCA at 7T would enhance the performance of DSC, as measured by contrast-to-noise ratio (CNR). METHODS: Ten patients (13 lesions) were assigned to 3T (6 patients, 6 lesions) or 7T (4 patients, 7 lesions). All lesions received 0.1 mmol/kg of GBCA on day 1. Ten lesions (4 at 3T and 6 at 7T) received a lower dose (0.6 mg/kg) of FBCA, followed by a higher dose (1.0-1.2 mg/kg), while 3 lesions (2 at 3T and 1 at 7T) received only a higher dose on Day 2. CBV maps with leakage correction for GBCA but not for FBCA were generated. The CNR and normalized CBV (nCBV) were analyzed on enhancing and non-enhancing high T2W lesions. RESULTS: Regardless of FBCA dose, GBCA showed higher CNR than FBCA at 7T, which was significant for high-dose FBCA (p < .05). Comparable CNR between GBCA and high-dose FBCA was observed at 3T. There was a trend toward higher CNR for FBCA at 3T than 7T. GBCA also showed nCBV twice that of FBCA at both MRI field strengths with significance at 7T. CONCLUSION: GBCA demonstrated higher image conspicuity, as measured by CNR, than FBCA on 7T. The stronger T2* weighting realized with higher magnetic field strength, combined with FBCA, likely results in more signal loss rather than enhanced performance on DSC. However, at clinical 3T, both GBCA and FBCA, particularly a dosage of 1.0-1.2 mg/kg (optimal for perfusion imaging), yielded comparable CNR.

Deciphering spatially distinct immune microenvironments in glioblastoma using ferumoxytol and gadolinium-enhanced and FLAIR hyperintense MRI phenotypes.

Background: MRI with gadolinium (Gd)-contrast agents is used to assess glioblastoma treatment response but does not specifically reveal heterogeneous biology or immune microenvironmental composition. Ferumoxytol (Fe) contrast is an iron nanoparticle that localizes glioblastoma macrophages and microglia. Therefore, we hypothesized that the use of Fe contrast improves upon standard Gd-based T1-weighted and T2/FLAIR analysis by specifically delineating immune processes. Methods: In this, HIPAA-compliant institutional review board-approved prospective study, stereotactic biopsy samples were acquired from patients with treatment-naïve and recurrent glioblastoma based on MR imaging phenotypes; Gd and Fe T1 enhancement (Gd+, Fe+) or not (Gd-, Fe-), as well as T2-Flair hyperintensity (FLAIR+, FLAIR-). Analysis of genetic expression was performed with RNA microarrays. Imaging and genomic expression patterns were compared using false discovery rate statistics. Results: MR imaging phenotypes defined a variety of immune pathways and Hallmark gene sets. Gene set enrichment analysis demonstrated that Gd+, Fe+, and FLAIR+ features were individually correlated with the same 7 immune process gene sets. Fe+ tissue showed the greatest degree of immune Hallmark gene sets compared to Gd+ or Flair+ tissues and had statistically elevated M2 polarized macrophages, among others. Importantly, the FLAIR+ Gd+ and Fe- imaging phenotypes did not demonstrate expression of immune Hallmark gene sets. Conclusions: Our study demonstrates the potential of Fe and Gd-enhanced MRI phenotypes to reveal spatially distinct immune processes within glioblastoma. Fe improves upon the standard of care Gd enhancement by specifically localizing glioblastoma-associated inflammatory processes, providing valuable insights into tumor biology.

Multiparametric magnetic resonance imaging discerns glioblastoma immune microenvironmental heterogeneity.

RATIONALE AND OBJECTIVE: Poor clinical outcomes for patients with glioblastoma are in part due to dysfunction of the tumor-immune microenvironment. An imaging approach able to characterize immune microenvironmental signatures could provide a framework for biologically based patient stratification and response assessment. We hypothesized spatially distinct gene expression networks can be distinguished by multiparametric Magnetic Resonance Imaging (MRI) phenotypes. MATERIALS AND METHODS: Patients with newly diagnosed glioblastoma underwent image-guided tissue sampling allowing for co-registration of MRI metrics with gene expression profiles. MRI phenotypes based on gadolinium contrast enhancing lesion (CEL) and non-enhancing lesion (NCEL) regions were subdivided based on imaging parameters (relative cerebral blood volume (rCBV) and apparent diffusion coefficient (ADC)). Gene set enrichment analysis and immune cell type abundance was estimated using CIBERSORT methodology. Significance thresholds were set at a p-value cutoff 0.005 and an FDR q-value cutoff of 0.1. RESULTS: Thirteen patients (eight men, five women, mean age 58 ± 11 years) provided 30 tissue samples (16 CEL and 14 NCEL). Six non-neoplastic gliosis samples differentiated astrocyte repair from tumor associated gene expression. MRI phenotypes displayed extensive transcriptional variance reflecting biological networks, including multiple immune pathways. CEL regions demonstrated higher immunologic signature expression than NCEL, while NCEL regions demonstrated stronger immune signature expression levels than gliotic non-tumor brain. Incorporation of rCBV and ADC metrics identified sample clusters with differing immune microenvironmental signatures. CONCLUSION: Taken together, our study demonstrates that MRI phenotypes provide an approach for non-invasively characterizing tumoral and immune microenvironmental glioblastoma gene expression networks.

Intravenous N-Acetylcysteine to Prevent Cisplatin-Induced Hearing Loss in Children: A Nonrandomized Controlled Phase I Trial.

PURPOSE: Cisplatin-induced hearing loss (CIHL) is common and permanent. As compared with earlier otoprotectants, we hypothesized N-acetylcysteine (NAC) offers potential for stronger otoprotection through stimulation of glutathione (GSH) production. This study tested the optimal dose, safety, and efficacy of NAC to prevent CIHL. PATIENTS AND METHODS: In this nonrandomized, controlled phase Ia/Ib trial, children and adolescents newly diagnosed with nonmetastatic, cisplatin-treated tumors received NAC intravenously 4 hours post-cisplatin. The trial performed dose-escalation across three dose levels to establish a safe dose that exceeded the targeted peak serum NAC concentration of 1.5 mmol/L (as identified from preclinical models). Patients with metastatic disease or who were otherwise ineligible were enrolled in an observation-only/control arm. To evaluate efficacy, serial age-appropriate audiology assessments were performed. Integrated biology examined genes involved in GSH metabolism and post-NAC GSH concentrations. RESULTS: Of 52 patients enrolled, 24 received NAC and 28 were in the control arm. The maximum tolerated dose was not reached; analysis of peak NAC concentration identified 450 mg/kg as the recommended phase II dose (RP2D). Infusion-related reactions were common. No severe adverse events occurred. Compared with the control arm, NAC decreased likelihood of CIHL at the end of cisplatin therapy [OR, 0.13; 95% confidence interval (CI), 0.021-0.847; P = 0.033] and recommendations for hearing intervention at end of study (OR, 0.082; 95% CI, 0.011-0.60; P = 0.014). NAC increased GSH; GSTP1 influenced risk for CIHL and NAC otoprotection. CONCLUSIONS: NAC was safe at the RP2D, with strong evidence for efficacy to prevent CIHL, warranting further development as a next-generation otoprotectant.

Safety of intra-arterial chemotherapy with or without osmotic blood-brain barrier disruption for the treatment of patients with brain tumors.

Background: Intra-arterial administration of chemotherapy with or without osmotic blood-brain barrier disruption enhances delivery of therapeutic agents to brain tumors. The aim of this study is to evaluate the safety of these procedures. Methods: Retrospectively collected data from a prospective database of consecutive patients with primary and metastatic brain tumors who received intra-arterial chemotherapy without osmotic blood-brain barrier disruption (IA) or intra-arterial chemotherapy with osmotic blood-brain barrier disruption (IA/OBBBD) at Oregon Health and Science University (OHSU) between December 1997 and November 2018 is reported. Chemotherapy-related complications are detailed per Common Terminology Criteria for Adverse Events (CTCAE) guidelines. Procedure-related complications are grouped as major and minor. Results: 4939 procedures (1102 IA; 3837 IA/OBBBD) were performed on 436 patients with various pathologies (primary central nervous system lymphoma [26.4%], glioblastoma [18.1%], and oligodendroglioma [14.7%]). Major procedure-related complications (IA: 12, 1%; IA/OBBBD: 27, 0.7%; P = .292) occurred in 39 procedures including 3 arterial dissections requiring intervention, 21 symptomatic strokes, 3 myocardial infarctions, 6 cervical cord injuries, and 6 deaths within 3 days. Minor procedure-related complications occurred in 330 procedures (IA: 41, 3.7%; IA/OBBBD: 289, 7.5%; P = .001). Chemotherapy-related complications with a CTCAE attribution and grade higher than 3 was seen in 359 (82.3%) patients. Conclusions: We provide safety and tolerability data from the largest cohort of consecutive patients who received IA or IA/OBBBD. Our data demonstrate that IA or IA/OBBBD safely enhance drug delivery to brain tumors and brain around the tumor.

[18F]-fluoromisonidazole (FMISO) PET/MRI hypoxic fraction distinguishes neuroinflammatory pseudoprogression from recurrent glioblastoma in patients treated with pembrolizumab.

Response assessment after immunotherapy remains a major challenge in glioblastoma due to an expected increased incidence of pseudoprogression. Gadolinium-enhanced magnetic resonance imaging (MRI) is the standard for monitoring therapeutic response, however, is markedly limited in characterizing pseudoprogression. Given that hypoxia is an important defining feature of glioblastoma regrowth, we hypothesized that [18F]-fluoromisonidazole (FMISO) positron emission tomography (PET) could provide an additional physiological measure for the diagnosis of immunotherapeutic failure. Six patients with newly diagnosed glioblastoma who had previously received maximal safe resection followed by Stupp protocol CRT concurrent with pembrolizumab immunotherapy were recruited for FMISO PET and Gd-MRI at the time of presumed progression. The hypoxic fraction was defined as the ratio of hypoxic volume to T1-weighted gadolinium-enhancing volume. Four patients diagnosed with pseudoprogression demonstrated a mean hypoxic fraction of 9.8 ±â€…10%. Two with recurrent tumor demonstrated a mean hypoxic fraction of 131 ±â€…66%. Our results, supported by histopathology, suggest that the noninvasive assessment of hypoxic fraction by FMISO PET/MRI is clinically feasible and may serve as a biologically specific metric of therapeutic failure.

Pharmacological reduction of coagulation factor XI reduces macrophage accumulation and accelerates deep vein thrombosis resolution in a mouse model of venous thrombosis.

BACKGROUND: Deep vein thrombosis (DVT) and post-thrombotic syndrome (PTS) remain highly prevalent despite modern medical therapy. Contact activation is a promising target for safe antithrombotic anticoagulation. The anti-factor XI (FXI) monoclonal antibody 14E11 reduces circulating levels of FXI without compromising hemostasis. The human recombinant analog, AB023, is in clinical development. The role of FXI in mediation of inflammation during DVT resolution is unknown. OBJECTIVES: Investigate the effects of pharmacological targeting of FXI with 14E11 in an experimental model of venous thrombosis. METHODS: Adult wild-type CD1 mice were treated with subcutaneous anti-FXI antibody (14E11, 5 mg/kg) versus saline prior to undergoing surgical constriction of the inferior vena cava (IVC). Mice were evaluated at various time points to assess thrombus weight and volume, as well as histology analysis, ferumoxytol enhanced magnetic resonance imaging (Fe-MRI), and whole blood flow cytometry. RESULTS: 14E11-treated mice had reduced thrombus weights and volumes after IVC constriction on day 7 compared to saline-treated mice. 14E11 treatment reduced circulating monocytes by flow cytometry and macrophage content within thrombi as evaluated by histologic staining and Fe-MRI. Collagen deposition was increased at day 3 while CD31 and smooth muscle cell actin expression was increased at day 7 in the thrombi of 14E11-treated mice compared to saline-treated mice. CONCLUSION: Pharmacologic targeting of FXI enhances the early stages of experimental venous thrombus resolution in wild-type CD1 mice, and may be of interest for future clinical evaluation of the antibody in DVT and PTS.

Diagnostic performance of DSC perfusion MRI to distinguish tumor progression and treatment-related changes: a systematic review and meta-analysis.

Background: In patients with high-grade glioma (HGG), true disease progression and treatment-related changes often appear similar on magnetic resonance imaging (MRI), making it challenging to evaluate therapeutic response. Dynamic susceptibility contrast (DSC) MRI has been extensively studied to differentiate between disease progression and treatment-related changes. This systematic review evaluated and synthesized the evidence for using DSC MRI to distinguish true progression from treatment-related changes. Methods: We searched Ovid MEDLINE and the Ovid MEDLINE in-process file (January 2005-October 2019) and the reference lists. Studies on test performance of DSC MRI using relative cerebral blood volume in HGG patients were included. One investigator abstracted data, and a second investigator confirmed them; two investigators independently assessed study quality. Meta-analyses were conducted to quantitatively synthesize area under the receiver operating curve (AUROC), sensitivity, and specificity. Results: We screened 1177 citations and included 28 studies with 638 patients with true tumor progression, and 430 patients with treatment-related changes. Nineteen studies reported AUROC and the combined AUROC is 0.85 (95% CI, 0.81-0.90). All studies contributed data for sensitivity and specificity, and the pooled sensitivity and specificity are 0.84 (95% CI, 0.80-0.88), and 0.78 (95% CI, 0.72-0.83). Extensive subgroup analyses based on study, treatment, and imaging characteristics generally showed similar results. Conclusions: There is moderate strength of evidence that relative cerebral blood volume obtained from DSC imaging demonstrated "excellent" ability to discriminate true tumor progression from treatment-related changes, with robust sensitivity and specificity.

Advances in Intraarterial Chemotherapy Delivery Strategies and Blood-Brain Barrier Disruption.

Chemotherapeutics play a significant role in the management of most brain tumors. First pass effect, systemic toxicity, and more importantly, the blood-brain barrier pose significant challenges to the success of chemotherapy. Over the last 80 years, different techniques of intraarterial chemotherapy delivery have been performed in many studies but failed to become standard of care. The purpose of this article is to review the history of intraarterial drug delivery and osmotic blood-brain barrier disruption, identify the challenges for clinical translation, and identify future directions for these approaches.

Radiation enhances the delivery of antisense oligonucleotides and improves chemo-radiation efficacy in brain tumor xenografts.

Overexpression of O6-methylguanine DNA methyltransferase (MGMT) contributes to resistance to chemo-radiation therapy (CRT) in brain tumors. We previously demonstrated that non-ablative radiation improved delivery of anti-MGMT morpholino oligonucleotides (AMONs) to reduce MGMT levels in subcutaneous tumor xenografts. We evaluate this approach to enhance CRT efficacy in rat brain tumor xenograft models. The impact of radiation on targeted delivery was evaluated using fluorescent oligonucleotides (f-ON). In vitro, f-ON was localized to clathrin-coated vesicles, endosomes, and lysosomes using confocal microscopy in T98G glioma cells. In vivo, fluorescence was detected in pre-radiated, but not non-radiated Long Evans (non-tumor bearing) rat brains. Cranial radiation (2 Gy) followed by AMONs (intravenous, 10.5 mg/kg) reduced MGMT expression by 50% in both orthotopic cerebellar D283 medulloblastoma and intracerebral H460 non-small cell lung carcinoma (NSCLC) xenograft models. To evaluate the efficacy, AMONs concurrent with CRT (2 Gy radiation plus oral 20 mg/kg temozolomide ×4 days) reduced tumor volumes in the medulloblastoma model (p = 0.012), and a similar trend was found in the NSCLC brain metastasis model. We provide proof of concept for the use of non-ablative radiation to guide and enhance the delivery of morpholino oligonucleotides into brain tumor xenograft models to reduce MGMT levels and improve CRT efficacy.

Blood-brain barrier opening by intracarotid artery hyperosmolar mannitol induces sterile inflammatory and innate immune responses.

Intracarotid arterial hyperosmolar mannitol (ICAHM) blood-brain barrier disruption (BBBD) is effective and safe for delivery of therapeutics for central nervous system malignancies. ICAHM osmotically alters endothelial cells and tight junction integrity to achieve BBBD. However, occurrence of neuroinflammation following hemispheric BBBD by ICAHM remains unknown. Temporal proteomic changes in rat brains following ICAHM included increased damage-associated molecular patterns, cytokines, chemokines, trophic factors, and cell adhesion molecules, indicative of a sterile inflammatory response (SIR). Proteomic changes occurred within 5 min of ICAHM infusion and returned to baseline by 96 h. Transcriptomic analyses following ICAHM BBBD further supported an SIR. Immunohistochemistry revealed activated astrocytes, microglia, and macrophages. Moreover, proinflammatory proteins were elevated in serum, and proteomic and histological findings from the contralateral hemisphere demonstrated a less pronounced SIR, suggesting neuroinflammation beyond regions of ICAHM infusion. Collectively, these results demonstrate ICAHM induces a transient SIR that could potentially be harnessed for neuroimmunomodulation.

Consensus recommendations for MRI and PET imaging of primary central nervous system lymphoma: guideline statement from the International Primary CNS Lymphoma Collaborative Group (IPCG).

Advanced molecular and pathophysiologic characterization of primary central nervous system lymphoma (PCNSL) has revealed insights into promising targeted therapeutic approaches. Medical imaging plays a fundamental role in PCNSL diagnosis, staging, and response assessment. Institutional imaging variation and inconsistent clinical trial reporting diminishes the reliability and reproducibility of clinical response assessment. In this context, we aimed to: (1) critically review the use of advanced positron emission tomography (PET) and magnetic resonance imaging (MRI) in the setting of PCNSL; (2) provide results from an international survey of clinical sites describing the current practices for routine and advanced imaging, and (3) provide biologically based recommendations from the International PCNSL Collaborative Group (IPCG) on adaptation of standardized imaging practices. The IPCG provides PET and MRI consensus recommendations built upon previous recommendations for standardized brain tumor imaging protocols (BTIP) in primary and metastatic disease. A biologically integrated approach is provided to addresses the unique challenges associated with the imaging assessment of PCNSL. Detailed imaging parameters facilitate the adoption of these recommendations by researchers and clinicians. To enhance clinical feasibility, we have developed both "ideal" and "minimum standard" protocols at 3T and 1.5T MR systems that will facilitate widespread adoption.

Long-Term Outcomes of Intra-Arterial Chemotherapy for Progressive or Unresectable Pilocytic Astrocytomas: Case Studies.

BACKGROUND: Progressive and/or unresectable pilocytic astrocytomas (PAs) carry a poor prognosis compared to typical PA. Early radiotherapy (RT) may have severe long-term neurocognitive side effects in this patient population. Intra-arterial (IA) chemotherapy is a viable alternative or addition to intravenous (IV) chemotherapy, which may be beneficial in avoidance of early RT. OBJECTIVE: To evaluate the safety and efficacy of IA chemotherapy in this subset of patients. METHODS: This is a retrospective review of medical records of PA patients who are treated with IA chemotherapy at Oregon Health & Science University from 1997 until 2019. Response to treatment was categorized as complete response (CR), partial response (PR), stable disease (SD), or progressive disease (PD). Progression free survival (PFS) and overall survival (OS) are also reported. RESULTS: Twelve patients were identified. All patients experienced progression prior to initiation of IA chemotherapy. The most common grade 3 or 4 toxicities related to chemotherapy were thrombocytopenia (66%), neutropenia (66%), leukopenia (50%), anemia (33%), and lymphopenia (16%). Responses achieved were CR in 1, PR in 3, SD in 7, and PD in 1. Median PFS and median OS were 16.5 and 83.5 mo, respectively. A total of 112 procedures (IA injections) were performed and 250 arteries were catheterized. There were 3 minor and no major complications attributable to procedures. CONCLUSION: This study demonstrates that IA chemotherapy can be safely used in patients with unresectable or progressive PA.

Risk Factors and Disease Course for Blood-Brain Barrier Disruption-Associated Maculopathy.

Importance: Blood-brain barrier disruption (BBBD) is a systemic therapy for malignant central nervous system (CNS) tumors that has been linked to poorly understood pigmentary maculopathy. Objectives: To examine the rate of and risk factors for the development of BBBD-associated maculopathy and to assess whether there can be visually significant progression after completion of systemic therapy. Design, Setting, and Participants: In this retrospective case series, data from February 1, 2006, through December 31, 2019, were collected from patients treated with osmotic BBBD at a single tertiary referral center who had subsequent ophthalmic evaluation. Exposures: Treatment with BBBD therapy for any malignant CNS tumor. Main Outcomes and Measures: Rate and potential risk factors for developing BBBD-associated maculopathy and changes in visual acuity and retinal imaging characteristics after completion of BBBD therapy. Results: Of 283 patients treated with BBBD and chemotherapy for a CNS malignant neoplasm, 68 (mean [SD] age, 46.0 [17.9] years; 25 [38.5%] female) had an ophthalmic examination after starting systemic therapy. After excluding 3 patients because of bilateral media opacities, pigmentary maculopathy was present in 32 of 65 patients (49.2%) treated with BBBD. The number of BBBD treatment sessions, but not age, CNS malignant cancer type, or systemic chemotherapy agent, was associated with maculopathy development (odds ratio, 1.30; 95% CI, 1.12-1.50; P = .001). After completion of BBBD therapy, progressive enlargement of geographic atrophy occurred in 5 eyes of 3 patients, and choroidal neovascularization developed in 1 eye. Conclusions and Relevance: In this case series, an association was found between BBBD-related maculopathy and the number of BBBD treatment sessions, suggesting a dose-dependent effect. In some cases, maculopathy progression, including enlargement of geographic atrophy, occurred years after completion of systemic therapy. These findings may have important implications for patient education and ophthalmic monitoring.

The clinical heterogeneity of entirely nonenhancing CNS lymphoma: a case series.

CNS lymphoma often presents with atypical imaging characteristics leading to delay in diagnosis and initiation of treatment. Among the most rarely reported of these is entirely nonenhancing CNS lymphoma, which is estimated at an incidence of about 1%. Here, we present three cases of nonenhancing CNS lymphoma in immune competent patients at both initial presentation and recurrence and in primary as well as secondary CNS lymphoma. Diffusion- and perfusion-weighted imaging was found helpful in diagnosis in some cases.

Ferumoxytol-Enhanced MRI Is Not Inferior to Gadolinium-Enhanced MRI in Detecting Intracranial Metastatic Disease and Metastasis Size.

OBJECTIVE. The goal of this intraindividual comparison study was to investigate whether ferumoxytol-enhanced MRI is as effective as standard-of-care gadolinium-enhanced MRI in detecting intracranial metastatic disease. MATERIALS AND METHODS. We retrospectively reviewed all patients who underwent imaging as part of two ongoing ferumoxytol-enhanced and gadolinium-enhanced MRI protocol studies to compare the number and size of enhancing metastatic lesions. Two neuroradiologists independently measured enhancing metastases on ferumoxytol-enhanced MR images and on control gadolinium-enhanced MR images. The number and size of metastases were compared on an intraindividual basis. Primary diagnoses were recorded. A linear mixed-effects model was used to compare differences in cubic root of volume between gadolinium-enhanced and ferumoxytol-enhanced MRI. A signed rank test was used to evaluate differences between reviewers. RESULTS. MR images from 19 patients with brain metastases were analyzed (seven with lung cancer, three with breast cancer, three with melanoma, two with ovarian cancer, one with colon cancer, one with renal cell carcinoma, one with carcinoid tumor, and one with uterine cancer). Reviewer 1 identified 77 masses on ferumoxytol-enhanced MRI and 72 masses on gadolinium-enhanced MRI. Reviewer 2 identified 83 masses on ferumoxytol-enhanced MRI and 78 masses on gadolinium-enhanced MRI. For reviewer 1, ferumoxytol-enhanced MRI showed a mean tumor size measuring 1.1 mm larger in each plane compared with gadolinium-enhanced MRI (p = 0.1887). For reviewer 2, ferumoxytol-enhanced MRI showed a mean tumor size measuring 1.0 mm larger in each plane (p = 0.2892). No significant differences in number of metastases or tumor sizes were observed between contrast agents or reviewers. CONCLUSION. Intracranial metastatic disease detection with ferumoxytol-enhanced MRI was not inferior to detection with gadolinium-enhanced MRI. Ferumoxytol-enhanced MRI could improve workup and monitoring of patients with brain metastases if gadolinium-enhanced MRI is contraindicated.

Transcriptional signatures in histologic structures within glioblastoma tumors may predict personalized drug sensitivity and survival.

BACKGROUND: Glioblastoma is a rapidly fatal brain cancer that exhibits extensive intra- and intertumoral heterogeneity. Improving survival will require the development of personalized treatment strategies that can stratify tumors into subtypes that differ in therapeutic vulnerability and outcomes. Glioblastoma stratification has been hampered by intratumoral heterogeneity, limiting our ability to compare tumors in a consistent manner. Here, we develop methods that mitigate the impact of intratumoral heterogeneity on transcriptomic-based patient stratification. METHODS: We accessed open-source transcriptional profiles of histological structures from 34 human glioblastomas from the Ivy Glioblastoma Atlas Project. Principal component and correlation network analyses were performed to assess sample inter-relationships. Gene set enrichment analysis was used to identify enriched biological processes and classify glioblastoma subtype. For survival models, Cox proportional hazards regression was utilized. Transcriptional profiles from 156 human glioblastomas were accessed from The Cancer Genome Atlas to externally validate the survival model. RESULTS: We showed that intratumoral histologic architecture influences tumor classification when assessing established subtyping and prognostic gene signatures, and that indiscriminate sampling can produce misleading results. We identified the cellular tumor as a glioblastoma structure that can be targeted for transcriptional analysis to more accurately stratify patients by subtype and prognosis. Based on expression from cellular tumor, we created an improved risk stratification gene signature. CONCLUSIONS: Our results highlight that biomarker performance for diagnostics, prognostics, and prediction of therapeutic response can be improved by analyzing transcriptional profiles in pure cellular tumor, which is a critical step toward developing personalized treatment for glioblastoma.

Maculopathy Associated With Osmotic Blood- Brain Barrier Disruption and Chemotherapy in Patients With Primary CNS Lymphoma.

BACKGROUND AND OBJECTIVE: To describe the incidence, characteristics, and risk factors of a pigmentary maculopathy in patients with primary central nervous system (CNS) lymphoma treated with blood-brain barrier disruption (BBBD) therapy. PATIENTS AND METHODS: This retrospective chart review included patients with biopsy-proven primary CNS lymphoma treated with or without BBBD therapy who underwent an ophthalmic examination after starting systemic treatment. Clinical data and all available retinal imaging were analyzed. RESULTS: Fifty-eight patients met inclusion criteria. Twenty-one of 36 patients treated with BBBD therapy had a bilateral pigmentary maculopathy. None of the 22 patients treated with conventional chemotherapy had similar changes. Additional findings in patients treated with BBBD included geographic retinal pigment epithelium atrophy, subretinal fluid, and in one case, choroidal neovascularization. Some cases of maculopathy resulted in reduced visual acuity. The presence of a pigmentary maculopathy was associated with a higher number of BBBD treatment sessions (20.1 vs 13.3, P = .016), but not vitreoretinal lymphoma involvement or intravitreal methotrexate injections. CONCLUSION: In this cohort, 58.3% of patients with primary CNS lymphoma treated with BBBD and chemotherapy were found to have a bilateral pigmentary maculopathy. This maculopathy can result in reduced visual acuity and is associated with the number of BBBD treatment sessions. [Ophthalmic Surg Lasers Imaging Retina. 2020;51:S5-S12.].

Impact of maintenance rituximab on duration of response in primary central nervous system lymphoma.

PURPOSE: The role of maintenance immunotherapy with anti-CD20 monoclonal antibody rituximab in primary central nervous system lymphoma (PCNSL) is unclear. We retrospectively reviewed the medical records of all immunocompetent adults with newly diagnosed PCNSL treated at our institution between1996 and 2017. METHODS: We identified 66 patients who attained complete response (CR) after completion of first-line regimen; 20 received maintenance therapy (maintenance therapy group) and 46 were observed with serial MRI scans without maintenance therapy (no-maintenance therapy group). RESULTS: Compared to the surveillance group, there was a significant increase in duration of survival (HR 0.27, 95% CI 0.08-0.98, P = 0.046) in the maintenance therapy group while the reduction in the risk of progression was not significant (HR: 0.61, 95% CI 0.26-1.43, P = 0.259). CONCLUSION: We are evaluating the effectiveness of maintenance immunotherapy in PCNSL in a prospective multicenter randomized clinical trial.

Toll-like Receptor 4 Signaling and Downstream Neutrophilic Inflammation Mediate Endotoxemia-Enhanced Blood-Labyrinth Barrier Trafficking.

HYPOTHESIS: Both toll-like receptor 4 (TLR4) and downstream neutrophil activity are required for endotoxemia-enhanced blood-labyrinth barrier (BLB) trafficking. BACKGROUND: Aminoglycoside and cisplatin are valuable clinical therapies; however, these drugs often cause life-long hearing loss. Endotoxemia enhances the ototoxicity of aminoglycosides and cisplatin in a TLR4 dependent mechanism for which downstream proinflammatory signaling orchestrates effector immune cells including neutrophils. Neutrophil-mediated vascular injury (NMVI) can enhance molecular trafficking across endothelial barriers and may contribute to endotoxemia-enhanced drug-induced ototoxicity. METHODS: Lipopolysaccharide (LPS) hypo-responsive TLR4-KO mice and congenitally neutropenic granulocyte colony-stimulating factor (GCSF) GCSF-KO mice were studied to investigate the relative contributions of TLR4 signaling and downstream neutrophil activity to endotoxemia-enhanced BLB trafficking. C57Bl/6 wild-type mice were used as a positive control. Mice were treated with LPS and 24 hours later cochleae were analyzed for gene transcription of innate inflammatory cytokine/chemokine signaling molecules, neutrophil recruitment, and vascular trafficking of the paracellular tracer biocytin-TMR. RESULTS: Cochlear transcription of innate proinflammatory cytokines/chemokines was increased in endotoxemic C57Bl/6 and GCSF-KO, but not in TLR4-KO mice. More neutrophils were recruited to endotoxemic C57Bl/6 cochleae compared with both TLR4 and GCSF-KO cochleae. Endotoxemia enhanced BLB trafficking of biocytin-TMR in endotoxemic C57Bl/6 cochleae and this was attenuated in both TLR4 and GCSF-KO mice. CONCLUSION: Together these results suggest that TLR4-mediated innate immunity cytokine/chemokine signaling alone is not sufficient for endotoxemia-enhanced trafficking of biocytin-TMR and that downstream neutrophil activity is required to enhance BLB trafficking. Clinically, targeting neutrophilic inflammation could protect hearing during aminoglycoside, cisplatin, or other ototoxic drug therapies.