Prospective, randomized, multicenter clinical trial evaluating longitudinal changes in brain function and microstructure in first-episode schizophrenia patients treated with long-acting injectable paliperidone palmitate versus oral antipsychotics

Widespread anatomical alterations and abnormal functional connectivity have shown strong association with symptom severity in first-episode schizophrenia (FES) patients. Second-generation antipsychotic treatment might slow disease progression and possibly modify the cerebral plasticity in FES patients. However, whether a long-acting injectable antipsychotic (paliperidone palmitate [PP]), available in monthly and every-3-months formulations, is more effective than oral antipsychotics (OAP) in improving cerebral organization has been unclear. Therefore, in the current longitudinal study, we evaluated the differences in functional and microstructural changes of 68 FES patients in a randomized clinical trial of PP vs OAP. When compared to OAP treatment, PP treatment was more effective in decreasing abnormally high fronto-temporal and thalamo-temporal connectivity, as well as increasing fronto-sensorimotor and thalamo-insular connectivity. Consistent with previous studies, multiple white matter pathways showed larger changes in fractional anisotropy (FA) and mean diffusivity (MD) in response to PP compared with OAP treatment. These findings suggest that PP treatment might reduce regional abnormalities and improve cerebral connectivity networks compared with OAP treatment, and identified changes that may serve as reliable imaging biomarkers associated with medication treatment efficacy.

Sex-specific brain microstructural reorganization in irritable bowel syndrome

ABSTRACT

Preliminary evidence suggests that there are sex differences in microstructural brain organization among individuals with irritable bowel syndrome (IBS). The aim of this study was to further investigate sex-dependent differences in brain microstructure and organization in a large sample of well-phenotyped participants with IBS compared with healthy controls. We hypothesized that female patients with IBS would show evidence for increased axonal strength and myelination within and between brain regions concerned with pain and sensory processing, when compared with males with IBS. We also hypothesized that female compared with male IBS subjects show greater levels of somatic awareness and sensory sensitivity consistent with multisystem sensory sensitivity. Diffusion tensor images and clinical assessments were obtained in 100 healthy controls (61 females) and 152 IBS (107 females) on a 3T Siemens Trio. Whole brain voxel-wise differences in fractional anisotropy, mean, radial and axial diffusivity, and track density as differences in somatic awareness and sensory sensitivity were assessed using the general linear model. Female compared with male IBS participants showed extensive microstructural alterations in sensorimotor, corticothalamic, and basal ganglia circuits involved in pain processing and integration of sensorimotor information. Together with the observed increases in symptom severity, somatic awareness, and sensory sensitivity, the findings support the hypotheses that the etiology and maintenance of symptoms in females with IBS may be driven by greater central sensitivity for multiple sensory stimuli.

Federated learning enables big data for rare cancer boundary detection

Although machine learning (ML) has shown promise across disciplines, out-of-sample generalizability is concerning. This is currently addressed by sharing multi-site data, but such centralization is challenging/infeasible to scale due to various limitations. Federated ML (FL) provides an alternative paradigm for accurate and generalizable ML, by only sharing numerical model updates. Here we present the largest FL study to-date, involving data from 71 sites across 6 continents, to generate an automatic tumor boundary detector for the rare disease of glioblastoma, reporting the largest such dataset in the literature (n = 6, 314). We demonstrate a 33% delineation improvement for the surgically targetable tumor, and 23% for the complete tumor extent, over a publicly trained model. We anticipate our study to: 1) enable more healthcare studies informed by large diverse data, ensuring meaningful results for rare diseases and underrepresented populations, 2) facilitate further analyses for glioblastoma by releasing our consensus model, and 3) demonstrate the FL effectiveness at such scale and task-complexity as a paradigm shift for multi-site collaborations, alleviating the need for data-sharing.

NIMG-44. PROGNOSTIC VALUE OF PH- AND OXYGEN-SENSITIVE MRI IN GLIOMA PATIENTS

Hypoxia and tissue acidosis are two key features of the glioma microenvironment, both associated with a more aggressive phenotype through promotion of invasion, angiogenesis, and resistance to a vast number of therapies. In the current study, we demonstrate that higher levels of acidity and hypoxia in glioma are associated with worse prognosis by using simultaneous pH- and oxygen-sensitive amine chemical exchange saturation transfer spin-and-gradient echo echo-planar imaging (CEST-SAGE-EPI). A total of 159 histologically confirmed adult glioma patients (WHO grade II: N = 42; grade III: N = 38; grade IV, N = 79) were retrospectively evaluated. All patients were scanned with a custom amine CEST-SAGE-EPI MRI pulse sequence at 3T. Magnetization transfer ratio asymmetry (MTRasym) at 3ppm was used as a measure of relative acidity, R2’ was used as a surrogate of hypoxia, and their product MTRasym×R2' was used to quantify the degree of both acidity and hypoxia. Cox regression was performed to evaluate prognostic factors for OS and PFS. Univariate results suggested higher hypoxia, R2' (HR = 1.44, p = 0.0002), and higher combined measure of acidity and hypoxia, MTRasym×R2' (HR = 1.14, p = 0.0008), were associated with a shorter OS. When considering age, treatment status, and IDH mutation status as covariates, R2' and MTRasym×R2' remained significantly associated with patient OS (R2': HR = 1.27, p = 0.045; MTRasym×R2': HR = 1.17, p = 0.002). Within the treatment naïve patients, tumor acidity MTRasym, was also associated with OS (HR = 3.72, p = 0.003). R2' and MTRasym×R2' were significantly associated with PFS, both using univariate (R2': p < 0.0001; MTRasym×R2': p < 0.0001) and multivariate analyses including clinical factors (R2': p = 0.010; MTRasym×R2': p < 0.0001). In summary, tumor acidity and hypoxia measured using pH- and oxygen-sensitive metabolic MRI are significant prognostic factors in glioma.

NIMG-41. PH-WEIGHTED MOLECULAR MRI AS AN EARLY BIOMARKER OF METABOLIC RESPONSE TO IDH INHIBITION IN IDH MUTANT GLIOMAS

The current study tested the hypotheses that (1) pH-weighted MRI measurements of tumor acidity reflect glycolytic activity in human gliomas, (2) that tumor acidity, and thus glycolytic activity, differs between human IDH mutant (mIDH) and wild type gliomas, and (3) that an increase in tumor acidity, suggestive of increased glycolytic activity, occurs after inhibition of mutant IDH enzyme activity and reduction in 2HG, an oncometabolite. To test these hypotheses, we employed a custom pH-weighted amine chemical exchange saturation transfer echoplanar (CEST-EPI) technique in 152 patients with IDH mutant or wildtype glioma prior to surgery and 11 patients before and after treatment with AG120 or AG881 enrolled at our institution in a phase 1 perioperative study in patients with recurrent, non-enhancing, IDH mutant low-grade gliomas (NCT03343197). Results from image-guided biopsies in more than 100 patients demonstrated a significant correlation between MTRasym at 3ppm, a measure of tumor acidity from pH-weighted amine CEST-EPI, and expression of key glycolytic proteins including GLUT3 (R2=0.2188,P=0.0105), HK2 (R2=0.1788,P=0.0314), LDHA (R2=0.1111,P=0.0071), and MCT1 (R2=0.1228,P=0.0039) as well as ex vivo extracellular flux analysis estimates of ATP consumption from glycolysis (R2=0.6684,P=0.0021). Data suggests a significantly lower acidity (MTRasym@3ppm) within non-enhancing tumor in IDH mutant gliomas when compared to IDH wild type gliomas (P< 0.0001). Patients in a phase 1 perioperative study showed a shift toward higher tumor acidity (i.e. higher glycolytic activity) following inhibition of IDH based on 2HG suppression in resected tumors, but at levels below that of IDH wild type gliomas. Levels of 2HG within the tumor after IDH inhibition were inversely correlated with post-treatment tumor acidity (R2=0.6342, P=0.0180). Overall, results suggest mIDH gliomas have low levels of glycolytic activity, and successful inhibition of the mutant IDH enzyme results in reduction in 2HG and a measurable metabolic shift toward elevated glycolysis as evidenced using pH-weighted molecular MRI.

NIMG-45. DIFFUSION MRI AS AN EARLY BIOMARKER OF OVERALL SURVIVAL BENEFIT IN RECURRENT GLIOBLASTOMA TREATED WITH IMMUNE CHECKPOINT INHIBITORS

Diffusion magnetic resonance imaging (MRI) estimates of the apparent diffusion coefficient (ADC) has been revealed to be useful for predicting treatment response in patients with glioblastoma (GBM), with an increase in ADC indicating tumor cell death. The aim of the current study was to investigate whether quantitative changes in diffusion MRI after treatment with immune checkpoint inhibitors (ICI) could predict OS in patients with recurrent GBM. A total of 61 patients were included in this retrospective study with the following inclusion criteria: (i) diagnosis of recurrent GBM treated either with pembrolizumab or nivolumab and (ii) availability of diffusion data in pre- and post-ICI MRI. Tumor volume and median relative apparent diffusion coefficient (rADC) within enhancing tumor with respect to normal-appearing white matter were calculated. Median OS for all patients was 7.6 months (range, 1.0–30.6 months). Results showed that higher post-treatment rADC was associated with significantly longer OS (median, 372 days for rADC ≧ 1.42 versus 211 days for rADC < 1.42; P = 0.01, log-rank test), whereas tumor volume and pre-treatment rADC were not significantly associated with OS. Cox regression analysis revealed post-treatment rADC significantly influences OS (P = 0.02, univariate analysis), even after controlling for age, sex, and IDH status (P = 0.007, multivariate analysis), and additionally controlling for whether surgery was performed after ICI treatment (P = 0.049, multivariate analysis). In conclusion, a high post-treatment rADC may be an early imaging biomarker for identifying OS benefit in recurrent GBM patients receiving ICI treatment.

Cortical morphometric correlational networks associated with cognitive deficits in first episode schizophrenia

Schizophrenia (SCZ) is a chronic cognitive and behavioral disorder associated with abnormal cortical activity during information processing. Several brain structures associated with the seven performance domains evaluated using the MATRICS (Measurement and Treatment Research to Improve Cognition in Schizophrenia) Consensus Cognitive Battery (MCCB) have shown cortical volume loss in first episode schizophrenia (FES) patients. However, the relationship between morphological organization and MCCB performance remains unclear. Therefore, in the current observational study, high-resolution structural MRI scans were collected from 50 FES patients, and the morphometric correlation network (MCN) using cortical volume was established to characterize the cortical pattern associated with poorer MCCB performance. We also investigated topological properties, such as the modularity, the degree and the betweenness centrality. Our findings show structural volume was directly and strongly associated with the cognitive deficits of FES patients in the precuneus, anterior cingulate, and fusiform gyrus, as well as the prefrontal, parietal, and sensorimotor cortices. The medial orbitofrontal, fusiform, and superior frontal gyri were not only identified as the predominant nodes with high degree and betweenness centrality in the MCN, but they were also found to be critical in performance in several of the MCCB domains. Together, these results suggest a widespread cortical network is altered in FES patients and that performance on the MCCB domains is associated with the core pathophysiology of SCZ.

BIMG-11. PHARMACODYNAMIC EVALUATION OF IDH AND EGFR INHIBITION IN HUMAN GLIOMAS USING MOLECULAR MRI

Metabolic differences are inherent to specific glioma subtypes and can be altered using targeted treatments, including IDH and EGFR inhibition. Using a large cohort of patients scanned at UCLA and other centers over the last 5 years, we demonstrate that IDH, 1p19q, and EGFR alterations uniquely contribute to alterations in glycolysis and oxygen utilization using a clinically available molecular MRI technique termed amine chemical exchange saturation transfer spin-and-gradient-echo echoplanar imaging (CEST-SAGE-EPI). Our data shows that CEST-SAGE-EPI estimates of tumor acidity are strongly associated with the degree of glycolysis as evaluated with direct pH measurements, quantitative IHC, bioenergetics experiments, and correlations with 18F-FDG PET images. Data further reveals that IDH wild type gliomas have higher acidity and oxygen utilization compared with IDH mutant gliomas, 1p19q non-codeleted gliomas (astrocytomas) have higher tumor acidity compared to 1p19q codeleted gliomas (oligodendrogliomas), and EGFR amplified gliomas have higher oxygen utilization compared with non-amplified gliomas. Additionally, phase II clinical trial data suggests successful IDH inhibition results in an early and measurable increase in tumor acidity and further reduction in oxygen utilization, signifying suppression of oxidative phosphorylation and/or glutaminolysis in favor of glycolysis. Alternatively, phase II clinical trial data suggests successful EGFR inhibition with brain penetrant agents results in early reductions in tumor acidity and 18F-FDG PET uptake, consistent with a reduction in glycolysis. Data also indicates that continual increases in tumor acidity during routine follow-up after initial therapeutic changes results in uniformly worse outcomes in all tumor subtypes under all mentioned treatment scenarios.

Estimated clinical efficacy and radiographic response characteristics of PD1 inhibition in newly diagnosed and recurrent glioblastoma in clinical practice: A report from the iRANO Working Group

2521

Background: Despite concerns of immunotherapy-induced inflammatory response during PD1 inhibition, questions remain as to the true incidence of inflammatory response and potential clinical implications. The goals of the project were to use GBM patients pooled from academic centers to estimate radiographic PFS and OS, as well as determine the incidence of immunotherapy-induced inflammatory response. Methods: 152 patients with newly diagnosed (N = 57) or recurrent (N = 95) GBM treated with either nivolumab or pembrolizumab from Dana-Farber (N = 88), UCLA (N = 35) or UCSF (N = 29) were included in this study. Radiographic progression was defined by a 25% increase in bidirectional measurements according to RANO. Results: Median PFS and OS for newly diagnosed patients was 162 and 520 days, respectively, while median PFS and OS for recurrent patients was 72 and 225 days, respectively. No difference in OS was observed in recurrent patients treated with nivolumab vs. pembrolizumab (P = 0.58), but recurrent patients treated with nivolumab trended toward a longer PFS (P = 0.097). Of the recurrent patients with OS and PFS data available and radiographic progression, 95% of them progressed within 6 mos of starting treatment. Median post-progression survival (PPS) in recurrent patients with PFS < 6 mos was 151 days, while PPS for patients with PFS > 6 mos was 178 days (P = 0.51). In the 77 recurrent patients who progressed within 6 mos, 36.4% had an OS that was > 9 mos, while 63.6% had an OS < 9 mos, suggesting the majority of patients with “early progression” also died early and a minority of patients had what could be considered “immune-related inflammation”. Of the 81 recurrent patients with documented progression, only 2.5% showed stabilization within 3 mos of first progression, 30.9% died before the 3-month confirmation scan could be obtained, 24.7% showed continued tumor growth by 3 months, and 48.1% had no follow-up confirmatory imaging exams. Of the 70 patients who progressed within 6 mos and had documented death, 2.9% had disease stabilization, 31.4% died before the 3-month confirmation, and 75.7% had either documented tumor growth or had no follow-up confirmatory imaging exams. Conclusions: This study suggests immunotherapy-induced inflammation followed by a favorable PPS is uncommon in GBM. While patients treated with other types of immunotherapy may exhibit different imaging characteristics, these data provide an important basis to refine the iRANO criteria.