Non-enhancing Regions Research Articles

CTNI-51. A PHASE 0/1 STUDY OF BDTX-1535 IN RECURRENT GLIOBLASTOMA (GBM) PATIENTS WITH EGFR ALTERATIONS OR FUSIONS

Abstract BACKGROUND Alterations to epidermal growth factor receptor (EGFR) occur frequently in high-grade gliomas (HGG) and are critical to its pathogenesis. This Phase 0/1 study evaluates pharmacokinetic (PK), pharmacodynamic (PD), and clinical response to an ATP-competitive, irreversible EGFR inhibitor, BDTX-1535, in recurrent HGG patients with EGFR alterations and/or fusions. MATERIALS/METHODS Recurrent HGG patients with EGFR alterations (Arm A) or EGFR fusions (Arm B) received 5 days of BDTX-1535 at 200 mg/daily (cohort 1) or 400 mg/every other day (cohort 2) prior to planned resection at 2-4 hours following the final dose. In the Phase 0 component of the study, total and unbound drug concentrations were measured in tumor tissue (gadolinium (Gd) enhancing and non-enhancing regions), cerebrospinal fluid (CSF), and plasma using validated LC-MS/MS methods. A PK ‘trigger’ was defined as unbound drug concentration above 1 nM and 4.1 nM in Gd non-enhancing tumor in patients with EGFR mutations and amplification, respectively, determined eligibility for Phase 1 therapeutic dosing. PD response was assessed by quantification of percentage of positive pEGFR, pERK and MIB-1 cells in the surgical tumor tissue compared to baseline pre-treatment tissue. RESULTS Eleven recurrent HGG patients were enrolled (Arm A, n=11; Arm B, n=0). Mean unbound concentrations of BDTX-1535 in non-enhancing tumor regions were 11.9 nM and 18.8 nM in cohorts 1 and 2, respectively. Eight of nine (88.9%) evaluable patients exceeded the PK threshold and qualified for Phase 1. Suppression of pEGFR and MIB1 was observed in 55% and 67% of patients, respectively. No serious adverse events related to BDTX-1535 were observed. At the time of submission, median PFS and OS have not yet been reached. CONCLUSIONS BDTX-1535 is well-tolerated in recurrent HGG patients, achieves pharmacologically relevant concentrations in non-enhancing tumor tissue, and is associated with suppression of EGFR signaling. Efficacy data accompanying this PK/PD response will be reported.

CTNI-50. CLINICAL EFFICACY AND PK/PD RESPONSE IN A PHASE 0/2 STUDY OF NIRAPARIB PLUS RADIOTHERAPY FOR NEWLY-DIAGNOSED, MGMT-UNMETHYLATED GLIOBLASTOMA

Abstract BACKGROUND Poly (ADP-ribose) polymerase (PARP) mediates DNA damage response; niraparib is a PARP1/2-selective inhibitor. This Phase 0/2 study evaluates tumor pharmacokinetics (PK), pharmacodynamics (PD), and clinical efficacy of niraparib plus fractionated radiotherapy in newly diagnosed, O6-methylguanine methyltransferase (MGMT)-unmethylated glioblastoma (GBM). METHODS Newly-diagnosed GBM patients received 4 days of niraparib (300/200 mg QD) prior to planned resection 3-5 (cohort 1) or 8-10 hours (cohort 2) following the last dose. Tumor tissue (gadolinium-enhancing and non-enhancing regions), cerebrospinal fluid (CSF), and plasma were collected. Total and unbound drug concentrations were measured using validated LC-MS/MS methods. PARP inhibition was assessed by quantification of PAR induction after ex vivo irradiation vs non-irradiated control. A PK response was defined as unbound [niraparib] > 5-fold biochemical IC50 (19 nM) in non-enhancing tumor. Patients with MGMT-unmethylated tumors and a PK response were eligible for Phase 2 dosing of niraparib plus radiotherapy followed by niraparib monotherapy. RESULTS All Phase 0 patients (n=46) met the PK threshold. The mean unbound concentrations of niraparib in non-enhancing tumor regions were 335.1 nM (cohort 1; n=43) and 331.9 nM (cohort 2; n=3). Ex vivo PAR suppression was observed in 73% of the patients (24/33). 71.4% patients with unmethylated tumors were enrolled into Phase 2. Five patients in Phase 2 experienced Grade 4 thrombocytopenia related to niraparib and all adverse events resolved without sequelae. At a mean clinical follow-up of 13.4 months, median overall survival was 20.3 months. CONCLUSIONS Niraparib achieves pharmacologically relevant concentrations in non-enhancing, newly-diagnosed GBM tissue. Accompanying PD effects were observed in tumor tissue, no new safety signals were observed, and clinical outcomes were promising. A global Phase 3, open-label, randomized 2-arm study comparing niraparib versus temozolomide in adult patients with newly diagnosed, MGMT-unmethylated glioblastoma is underway.

NIMG-59. COMPARATIVE ANALYSIS OF LONG-TERM GLIOBLASTOMA SURVIVORS USING MACHINE LEARNING GENERATED RADIO-PATHOMIC METRICS

Abstract BACKGROUND Glioblastoma (GBM) remains the most devastating central nervous system malignancy with poor overall survival (OS), even with gross total resection (GTR) and chemoradiation. Identifying factors associated with long-term survival (LTS) in GBM patients is challenging but crucial for improving prognostic models. This study compares an internal dataset of the top 10% long-term survivors of GBM (n=14) against a combined external cohort of 528 GBM patients who underwent GTR. METHODS We used a previously published machine learning-generated radio-pathomic model based on autopsy tissue as ground-truth to generate whole-brain maps of cell density and tumor probability maps (TPM) using conventional preoperative MRI sequences in both our internal dataset and a combined external cohort of GBM patients who underwent GTR from the UCSF-PDGM-v2 and UPenn-GBM databases. We then analyzed clinical and radio-pathomic metrics, including cell density and TPM values within contrast-enhancing (CE) and FLAIR hyperintense regions. Statistical comparisons were performed using t-tests. RESULTS Cell density metrics showed significant differences, with lower cell density in contrast-enhancing regions (t-value: 4.709, p<0.001; median: 1559 vs. 1959) and in FLAIR hyperintense regions (t-value: 3.585, p<0.001; median: 1356 vs. 1568) within the LTS group. TPM metrics also showed significant differences, with lower TPM values in contrast-enhancing regions (t-value: 3.312, p<0.001; median: 0.71 vs. 0.72) and in non-enhancing regions (t-value: 2.606, p<0.01; median: 0.68 vs. 0.69) in the LTS group. CONCLUSION Our comparative analysis reveals distinct radio-pathomic characteristics associated with long-term survival in GBM patients. Reduced cell density and lower TPM values in both contrast-enhancing and FLAIR hyperintense regions are significantly correlated with long-term survival. These findings suggest that integrating radio-pathomic data may enhance prognostic models and warrants further studies evaluating the relationship of these markers and OS.

CTNI-58. A PHASE 0/2 TRIAL OF ABEMACICLIB PLUS LY3214996 IN RECURRENT GLIOBLASTOMA

Abstract BACKGROUND This Phase 0/2 study (NCT04391595) evaluates tumor pharmacokinetics (PK), tumor pharmacodynamics (PD), and clinical efficacy of abemaciclib, a CDK4 and 6 inhibitor, plus LY3214996, an ERK 1/2 inhibitor, in recurrent glioblastoma (rGBM). METHODS Adult rGBM patients (n=42) with intact RB, >30% pERK expression, and CDKN2A/B deletion or CDK4/6 amplification received six days of abemaciclib plus LY3214996 prior to a planned resection. Time-escalation cohorts (3-5 and 7-9 hour intervals from last dose to tumor resection) identified the optimal time interval (OTI). Subsequent Phase 0 patients had tumor tissue (gadolinium [Gd]-enhancing and nonenhancing regions), cerebrospinal fluid (CSF), and plasma collected at the OTI. Total and unbound drug concentrations were measured using validated LC-MS/MS methods. Tumor PD was compared to matched archival or pre-treatment biopsied tissue. A PK ‘trigger’ (i.e., unbound concentration > 5 x IC50) was set for each drug. Gd-nonenhancing tumor demonstrating PK response to both drugs qualified patients for the Phase 2 component of the study. RESULTS Forty two patients were accrued to Phase 0 and no dose-limiting toxicities were observed. Median unbound concentrations in Gd-nonenhancing tumor regions were 31 nM and 10 nM for abemaciclib and LY3214996, respectively. Tumor RB, RSK phosphorylation, and tumor proliferation (MIB-1) decreased in (47.5%), (25%) and (72.5%) patients, respectively. Nine of the 40 (22.5%) patients exceeded PK thresholds for both abemaciclib (12 nM) and LY3214996 (25 nM), qualifying them for Phase 2. Here, median PFS and median OS were 2.4 and 7.2 months, respectively. CONCLUSION Abemaciclib and LY3214996 achieved pharmacologically-relevant concentrations in Gd-non-enhancing GBM tissue in 80% and 30% of the patients, respectively. Suppression of the RB pathway and tumor proliferation, but not ERK pathway was observed. Inadequate CNS penetration and tumor PD modulation by LY3214996 contributed to the unremarkable clinical efficacy profile of this drug combination. Targeted ERK inhibition remains an unmet need in experimental GBM therapy.

TMIC-14. RAPID EARLY PROGRESSION IN GLIOBLASTOMA: A COMPREHENSIVE REVIEW OF CLINICAL, IMAGING AND HISTOPATHOLOGICAL FEATURES

Abstract BACKGROUND In glioblastoma patients, Rapid Early Progression (REP) refers to tumour growth between the time of surgery and postoperative chemoradiotherapy. Despite its high incidence relatively little is known about it. The aim of this study was to characterise REP using a combination of clinical, imaging and histopathology data. METHODS Ethical approval was obtained. Supratentorial IDH-wildtype glioblastomas undergoing gross-total resection (GTR) between 2015-2021 were included. REP was defined as a nodular increase in enhancement located within or around the surgical cavity, occurring within 6 weeks of surgery, that was not accounted for by initial areas of diffusion-restriction. REP cases were propensity-score matched to controls on baseline characteristics. Imaging was compared using mean apparent diffusion coefficient (ADC) and T1-postcontrast radiomics. Tissue analyses included DNA methylation subtyping and immunohistochemistry for markers of T-cells (CD3), microglia (P2RY12) and proliferation (PHH3). RESULTS REP occurred in 8/60 GTR cases (13%) and these patients were matched to 16 controls. REP cases had a worse preoperative performance status (median Eastern Cooperative Oncology Group [ECOG] 2 vs. 1), overall-survival (p=0.038) and progression-free survival (p = 0.029). REP was more common in patients over 65 years (27%) and significantly fewer REP patients received radical postoperative chemoradiotherapy (p=0.023). REP and control cases were well matched with respect to preoperative T1-postcontrast radiomics and mean ADC in enhancing (p=0.99) and non-enhancing regions (p=0.67). There was no relative excess of any one DNA methylation subtype in REP cases. The two groups had a similar proportion of T-cells (p=0.81), but REP cases had a trend towards a higher proportion of microglia (31% vs. 17%; p=0.22), and a lower proliferation rate (3% vs. 9%; p=0.19). CONCLUSION REP cases had a worse performance status from diagnosis and received less radical postoperative chemoradiotherapy protocols compared to controls, yielding a significantly shorter median OS/PFS. Differences in immune landscape and proliferation rate should be further investigated.

Prognostic nomogram model based on quantitative metrics of subregions surrounding residual cavity in glioblastoma patients

BackgroundThe hyperintensity area surrounding the residual cavity on postoperative fluid-attenuated inversion recovery (FLAIR) image is a potential site for glioblastoma (GBM) recurrence. This study aimed to develop a nomogram using quantitative metrics from subregions of this area, prior to chemoradiotherapy (CRT), to predict early GBM recurrence.MethodsAdult patients with GBM diagnosed between October 2018 and October 2022 were retrospectively analyzed. Quantitative metrics, including the mean, maximum, minimum, median values, and standard deviation of FLAIR signal intensity (SI) (measured using 3D-Slicer software), were extracted from the following subregions surrounding the residual cavity on post-contrast T1-weighted (CE-T1WI)-FLAIR fusion images: the enhancing region (ER), non-enhancing region (NER), and combined ER + NER. Independent prognostic factors were identified using Cox regression and least absolute shrinkage and selection operator (LASSO) analyses and were incorporated into the prediction nomogram model. The model’s performance was evaluated using the C-index, calibration curves, and decision curves.ResultsA total of 129 adult GBM patients were enrolled and randomly assigned to a training (n = 90) and a validation cohorts (n = 39) in a 7:3 ratio. Sixty-nine patients experienced postoperative recurrence. Cox regression analysis identified subventricular zone involvement, the median FLAIR intensity in the ER, the rFLAIR (relative FLAIR intensity compared to the contralateral normal region) of ER + NER, and corpus callosum involvement as independent prognostic factors. For predicting recurrence within 1 year after surgery, the nomogram model had a C-index of 0.733 in the training cohort and 0.746 in the validation cohort. Based on the nomogram score, post-operative GBM patients could be stratified into high- and low-risk for recurrence.ConclusionsNomogram models which based on quantitative metrics from FLAIR hyperintensity subregions may serve as potential markers for assessing GBM recurrence risk. This approach could enhance clinical decision-making and provide an alternative method for recurrence estimation in GBM patients.

DSC-PWI presurgical differentiation of grade 4 astrocytoma and glioblastoma in young adults: rCBV percentile analysis across enhancing and non-enhancing regions

PurposeThe presurgical discrimination of IDH-mutant astrocytoma grade 4 from IDH-wildtype glioblastoma is crucial for patient management, especially in younger adults, aiding in prognostic assessment, guiding molecular diagnostics and surgical planning, and identifying candidates for IDH-targeted trials. Despite its potential, the full capabilities of DSC-PWI remain underexplored. This research evaluates the differentiation ability of relative-cerebral-blood-volume (rCBV) percentile values for the enhancing and non-enhancing tumor regions compared to the more commonly used mean or maximum preselected rCBV values.MethodsThis retrospective study, spanning 2016–2023, included patients under 55 years (age threshold based on World Health Organization recommendations) with grade 4 astrocytic tumors and known IDH status, who underwent presurgical MR with DSC-PWI. Enhancing and non-enhancing regions were 3D-segmented to calculate voxel-level rCBV, deriving mean, maximum, and percentile values. Statistical analyses were conducted using the Mann-Whitney U test and AUC-ROC.ResultsThe cohort consisted of 59 patients (mean age 46; 34 male): 11 astrocytoma-4 and 48 glioblastoma. While glioblastoma showed higher rCBV in enhancing regions, the differences were not significant. However, non-enhancing astrocytoma-4 regions displayed notably higher rCBV, particularly in lower percentiles. The 30th rCBV percentile for non-enhancing regions was 0.705 in astrocytoma-4, compared to 0.458 in glioblastoma (p = 0.001, AUC-ROC = 0.811), outperforming standard mean and maximum values.ConclusionEmploying an automated percentile-based approach for rCBV selection enhances differentiation capabilities, with non-enhancing regions providing more insightful data. Elevated rCBV in lower percentiles of non-enhancing astrocytoma-4 is the most distinguishable characteristic and may indicate lowly vascularized infiltrated edema, contrasting with glioblastoma’s pure edema.

Niraparib efficacy in patients with newly-diagnosed glioblastoma: Clinical readout of a phase 0/2 "trigger" trial.

2002 Background: Poly (ADP-ribose) polymerase (PARP) mediates DNA damage response; niraparib is an investigational PARP1/2-selective inhibitor. This Phase 0 study evaluates newly-diagnosed glioblastoma (GBM) tumor pharmacokinetics (PK) and pharmacodynamics (PD), graduating patients with O6-methylguanine methyltransferase (MGMT) unmethylated tumors into a therapeutic regimen of niraparib plus fractionated radiotherapy when PK threshold is met. Methods: Presumed newly-diagnosed GBM patients received 4 days of niraparib (300/200 mg QD) prior to planned resection 3-5 (cohort 1) or 8-10 hours (cohort2) following the last dose. Tumor tissue (Gadolinium enhancing and non-enhancing regions), cerebrospinal fluid (CSF), and plasma were collected. Total and unbound niraparib concentrations were measured using validated LC-MS/MS methods. PARP inhibition was assessed by quantification of PAR induction after ex vivo irradiation of surgical vs non-irradiated tissue. A PK ‘trigger’ determined eligibility for the Phase 2 component of the study and was defined as unbound [niraparib] > 5-fold biochemical IC50 (i.e., 19 nM) in non-enhancing tumor. Patients with MGMT unmethylated tumors in excess of the PK threshold were eligible for Phase 2 dosing of niraparib plus radiotherapy followed by a maintenance phase of niraparib monotherapy. Results: All Phase 0 patients (n=46) met the PK threshold. In non-enhancing tumor regions, the mean unbound concentration of niraparib was 335.1 nM (n=43) for cohort 1 and 331.9 nM (n=3) for cohort 2. PAR suppression after ex vivo radiation was observed in 73% of the patients (24/33). Nineteen of 27 (70.3%) patients with unmethylated tumors were enrolled into Phase 2. Five patients in Phase 2 experienced Grade 4 thrombocytopenia related to niraparib. All adverse events resolved without sequelae. At time of data cutoff, median progression-free survival was 11.7 months. Mature overall survival (OS) data will be reported for the first time. Conclusions: Niraparib achieves pharmacologically relevant concentrations in non-enhancing, newly-diagnosed GBM tissue in excess of any other studied PARP inhibitor. Accompanying PD effects were observed in patient tumor tissue. For the first time, we report on the clinical efficacy of the study. A global Phase 3, open-label, randomized 2-arm study comparing niraparib versus temozolomide in adult patients with newly diagnosed, MGMT unmethylated glioblastoma is being planned. Clinical trial information: NCT05076513 .

A phase 0/1 trigger trial of BDTX-1535 in patients with recurrent high-grade glioma (HGG) with EGFR alterations or fusions.

2069 Background: This Phase 0/1 clinical trial evaluates the pharmacokinetic (PK), pharmacodynamic (PD), and clinical response of recurrent high-grade glioma (HGG) patients with EGFR alterations and/or fusions to the ATP-competitive, irreversible EGFR inhibitor, BDTX-1535. Methods: Recurrent HGG patients with EGFR alterations (Arm A) or EGFR fusions (Arm B) received 5 days of BDTX-1535 (200 mg) prior to planned resection at 2-4 hours following the final dose. In the Phase 0 component of the study, total and unbound drug concentrations were measured in tumor tissue (Gadolinium enhancing and non-enhancing regions), cerebrospinal fluid (CSF), and plasma using validated LC-MS/MS methods. A PK ‘trigger’, defined as unbound drug concentration above 5-fold biochemical IC50 in Gadolinium (Gd)-nonenhancing tumor, determined eligibility for Phase 1. PD response was assessed by quantification of percentage of positive pEGFR, pERK and MIB-1 cells in the surgical tumor tissue compared to baseline pre-treatment tissue. Patients with tumors exceeding the PK threshold for unbound drug concentration were eligible for expansion phase therapeutic dosing of BDTX-1535. Results: A total of 7 patients with recurrent glioblastoma (Arm A) were enrolled in the Phase 0 component of the study. Two patients were excluded from PK analysis due to pseudoprogression. The mean unbound concentrations of BDTX-1535 in Gd-enhancing and nonenhancing tumor regions were 16.0 nM and 10.5 nM respectively. Four of five (80%) evaluable patients exceeded the PK threshold. The suppression of pEGFR and MIB1 was observed in 40% and 60% of patients, respectively. No serious adverse events were observed among patients in the Phase 1 component of the study and a clinical readout is planned in Q2 2024. Conclusions: BDTX-1535 is well-tolerated in recurrent HGG patients, achieves pharmacologically relevant concentrations in Gd-nonenhancing tumor tissue and is associated with suppression of EGFR signaling. Clinical trial information: NCT06072586 .

Diagnosis of benign and malignant peripheral lung lesions based on a feature model constructed by the random forest algorithm for grayscale and contrast-enhanced ultrasound.

To construct a predictive model for benign and malignant peripheral pulmonary lesions (PPLs) using a random forest algorithm based on grayscale ultrasound and ultrasound contrast, and to evaluate its diagnostic value. We selected 254 patients with PPLs detected using chest lung computed tomography between October 2021 and July 2023, including 161 malignant and 93 benign lesions. Relevant variables for judging benign and malignant PPLs were screened using logistic regression analysis. A model was constructed using the random forest algorithm, and the test set was verified. Correlations between these relevant variables and the diagnosis of benign and malignant PPLs were evaluated. Age, lesion shape, size, angle between the lesion border and chest wall, boundary clarity, edge regularity, air bronchogram, vascular signs, enhancement patterns, enhancement intensity, homogeneity of enhancement, number of non-enhancing regions, non-enhancing region type, arrival time (AT) of the lesion, lesion-lung AT difference, AT difference ratio, and time to peak were the relevant variables for judging benign and malignant PPLs. Consequently, a model and receiver operating characteristic curve were constructed with an AUC of 0.92 and an accuracy of 88.2%. The test set results showed that the model had good predictive ability. The index with the highest correlation for judging benign and malignant PPLs was the AT difference ratio. Other important factors were lesion size, patient age, and lesion morphology. The random forest algorithm model constructed based on clinical data and ultrasound imaging features has clinical application value for predicting benign and malignant PPLs.

Single-nucleus expression characterization of non-enhancing region of recurrent high-grade glioma.

Non-enhancing (NE) infiltrating tumor cells beyond the contrast-enhancing (CE) bulk of tumor are potential propagators of recurrence after gross total resection of high-grade glioma. We leveraged single-nucleus RNA sequencing on 15 specimens from recurrent high-grade gliomas (n = 5) to compare prospectively identified biopsy specimens acquired from CE and NE regions. Additionally, 24 CE and 22 NE biopsies had immunohistochemical staining to validate RNA findings. Tumor cells in NE regions are enriched in neural progenitor cell-like cellular states, while CE regions are enriched in mesenchymal-like states. NE glioma cells have similar proportions of proliferative and putative glioma stem cells relative to CE regions, without significant differences in % Ki-67 staining. Tumor cells in NE regions exhibit upregulation of genes previously associated with lower grade gliomas. Our findings in recurrent GBM paralleled some of the findings in a re-analysis of a dataset from primary GBM. Cell-, gene-, and pathway-level analyses of the tumor microenvironment in the NE region reveal relative downregulation of tumor-mediated neovascularization and cell-mediated immune response, but increased glioma-to-nonpathological cell interactions. This comprehensive analysis illustrates differing tumor and nontumor landscapes of CE and NE regions in high-grade gliomas, highlighting the NE region as an area harboring likely initiators of recurrence in a pro-tumor microenvironment and identifying possible targets for future design of NE-specific adjuvant therapy. These findings also support the aggressive approach to resection of tumor-bearing NE regions.

CTNI-22. A PHASE 0/2 ‘TRIGGER’ TRIAL OF NIRAPARIB IN PATIENTS WITH NEWLY-DIAGNOSED GLIOBLASTOMA

Abstract BACKGROUND Poly (ADP-ribose) polymerase (PARP) mediates DNA damage response; niraparib is an investigational PARP1/2-selective inhibitor. This Phase 0 study evaluates newly-diagnosed glioblastoma (GBM) tumor pharmacokinetics (PK) and pharmacodynamics (PD), graduating patients with O6-methylguanine methyltransferase (MGMT) unmethylated tumors into a therapeutic regimen of niraparib plus fractionated radiotherapy when PK threshold is met. METHODS Presumed newly-diagnosed GBM patients received 4 days of niraparib (300/200 mg QD) prior to planned resection 3-5 or 8-12 hours following the last dose. Tumor tissue (enhancing and non-enhancing regions), cerebrospinal fluid (CSF), and plasma were collected. Total and unbound niraparib concentrations were measured using validated LC-MS/MS methods. PARP inhibition was assessed by quantification of PAR induction after ex vivo irradiation of surgical vs non-irradiated tissue. A PK ‘trigger’ determined eligibility for the therapeutic expansion phase and was defined as unbound [niraparib] > 5-fold biochemical IC50 (i.e., 19 nM) in non-enhancing tumor. Patients with MGMT unmethylated tumors and positive PK were eligible for phase 2 dosing of niraparib plus radiotherapy followed by a maintenance phase of niraparib. RESULTS All phase 0 patients (n = 44) met the PK threshold. In non-enhancing tumor regions, the mean unbound concentration of niraparib was 226.7 nM (n = 38). PAR suppression after ex vivo radiation was observed in 71% of the patients (20/28). Eighteen out of 26 patients with unmethylated tumors enrolled in phase 2. Five of the 18 initial patients in phase 2 experienced grade 4 thrombocytopenia related to niraparib. All adverse events were resolved without sequelae. For patients who completed at least 6 months of follow-up, PFS6 was 64% (n = 11) with 9.2-month median follow-up. Median follow-up for all patients (n = 18) was 4.2 months with 8 patients remaining on treatment and 2 patients ongoing PFS6 follow-up. CONCLUSIONS Niraparib achieves pharmacologically-relevant concentrations in non-enhancing, newly-diagnosed GBM tissue in excess of any other studied PARP inhibitor.

A Combined Phase 0/2 "Trigger" Trial of Niraparib in Combination with Radiation in Patients with Newly-Diagnosed Glioblastoma

Poly ADP-ribose (PAR) polymerase (PARP) mediates DNA damage response. Niraparib is an investigational PARP1/2-selective inhibitor. We conducted a combined phase 0/2 study to evaluate niraparib pharmacokinetics (PK) and pharmacodynamics (PD) in patients with newly-diagnosed glioblastoma (GBM), graduating patients to a phase 2 study evaluating a therapeutic regimen of niraparib with concurrent conventionally-fractionated radiotherapy (RT) in O6-methylguanine methyltransferase (MGMT) unmethylated tumors exceeding a prespecified PK threshold in non-enhancing tumor. Patients with presumed newly-diagnosed GBM were enrolled in a phase 0 study receiving 4 days of niraparib (300 or 200 mg QD) prior to planned resection 3-5 or 8-12 hours following the last dose. Tumor tissue (enhancing and non-enhancing regions), cerebrospinal fluid (CSF), and plasma were collected. Total and unbound niraparib concentrations were measured using validated LC-MS/MS methods. PARP inhibition was assessed by quantification of PAR induction after 10 Gy ex vivo irradiation in surgical tissue compared to non-irradiated control tissue. A PK 'trigger' determined eligibility for the therapeutic phase 2 expansion portion of the study. This was defined as unbound [niraparib] > 5-fold biochemical IC50 (i.e., 19 nM) in non-enhancing tumor. Patients with MGMT unmethylated tumors exceeding this PK threshold were eligible for expansion phase dosing of niraparib with concurrent RT followed by a maintenance phase of niraparib. Patients with MGMT methylated tumors were not eligible for the expansion phase and proceeded with temozolomide (TMZ) plus RT followed by maintenance TMZ. RT dose was 60 Gy in 30 fractions using volumetric-modulated arc therapy (VMAT). All 29 patients enrolled in the phase 0 portion of the study met the PK threshold. In non-enhancing regions, the mean unbound concentration of niraparib was 258.2 nM. The suppression of PAR levels after ex vivo RT was observed in 79% of the patients (17/22). Sixteen patients had unmethylated tumors, and of those, 11 patients enrolled in phase 2. Five of the 6 initial patients enrolled in phase 2 experienced thrombocytopenia related to niraparib, and 3/5 cases were deemed serious and life-threatening. Consequently, starting dose in both phases was lowered to 200 mg, and no serious AEs were observed thereafter. At a median follow-up of 8.1 months [range: 6.0-12.9 months], 6-month PFS was 64% with 4 patients remaining on treatment and 5 patients ongoing survival follow-up. Niraparib achieves pharmacologically-relevant concentrations in non-enhancing, newly-diagnosed GBM tissue in excess of any other studied PARP inhibitor. When delivered with concurrent RT, niraparib was well-tolerated, with low rates of grade 3+ toxicity. Initial clinical efficacy data are encouraging.

PH-Weighted amine chemical exchange saturation transfer echo planar imaging visualizes infiltrating glioblastoma cells.

Given the invasive nature of glioblastoma, tumor cells exist beyond the contrast-enhancing (CE) region targeted during treatment. However, areas of non-enhancing (NE) tumors are difficult to visualize and delineate from edematous tissue. Amine chemical exchange saturation transfer echo planar imaging (CEST-EPI) is a pH-sensitive molecular magnetic resonance imaging technique that was evaluated in its ability to identify infiltrating NE tumors and prognosticate survival. In this prospective study, CEST-EPI was obtained in 30 patients and areas with elevated CEST contrast ("CEST+" based on the asymmetry in magnetization transfer ratio: MTRasym at 3 ppm) within NE regions were quantitated. Median MTRasym at 3 ppm and volume of CEST + NE regions were correlated with progression-free survival (PFS). In 20 samples from 14 patients, image-guided biopsies of these areas were obtained to correlate MTRasym at 3 ppm to tumor and non-tumor cell burden using immunohistochemistry. In 15 newly diagnosed and 15 recurrent glioblastoma, higher median MTRasym at 3ppm within CEST + NE regions (P = .007; P = .0326) and higher volumes of CEST + NE tumor (P = .020; P < .001) were associated with decreased PFS. CE recurrence occurred in areas of preoperative CEST + NE regions in 95.4% of patients. MTRasym at 3 ppm was correlated with presence of tumor, cell density, %Ki-67 positivity, and %CD31 positivity (P = .001; P < .001; P < .001; P = .001). pH-weighted amine CEST-EPI allows for visualization of NE tumor, likely through surrounding acidification of the tumor microenvironment. The magnitude and volume of CEST + NE tumor correlates with tumor cell density, degree of proliferating or "active" tumor, and PFS.

Adaptive enhancement design of triply periodic minimal surface lattice structure based on non-uniform stress distribution

The Schwarz primitive triply periodic minimal surface (P-type TPMS) lattice structures are widely used. However, these lattice structures have weak load-bearing capacity compared with other cellular structures. In this paper, an adaptive enhancement design method based on the non-uniform stress distribution in structures with uniform thickness is proposed to design the P-type TPMS lattice structures with higher mechanical properties. Two types of structures are designed by adjusting the adaptive thickness distribution in the TPMS. One keeps the same relative density, and the other keeps the same of non-enhanced region thickness. Compared with the uniform lattice structure, the elastic modulus for the structure with the same relative density increases by more than 17%, and the yield strength increases by more than 10.2%. Three kinds of TPMS lattice structures are fabricated by laser powder bed fusion (L-PBF) with 316L stainless steel to verify the proposed enhanced design. The manufacture-induced geometric deviation between the as-design and as-printed models is measured by micro X-ray computed tomography (µ-CT) scans. The quasi-static compression experimental results of P-type TPMS lattice structures show that the reinforced structures have stronger elastic moduli, ultimate strengths, and energy absorption capabilities than the homogeneous P-TPMS lattice structure.

A phase 0 pharmacokinetic trigger trial of infigratinib in patients with recurrent high-grade glioma.

2051 Background: This Phase 0 trial evaluates tumor pharmacokinetic (PK) and pharmacodynamic (PD) responses of fibroblast growth factor receptor (FGFR) inhibitor, infigratinib, in participants with recurrent high-grade glioma carrying FGFR1 K656E or FGFR3 K650E mutation or FGFR3-TACC3 translocation. Patients with high unbound drug concentrations in the gadolinium-nonenhancing tumor region were graduated to a therapeutic regimen of infigratinib. Methods: Recurrent high-grade glioma patients received 7 days of infigratinib (125 mg QD) prior to planned resection at 7-9 hours following the last dose. Tumor tissue (enhancing and nonenhancing regions), cerebrospinal fluid (CSF), and plasma were collected. Total and unbound infigratinib concentrations were measured using validated LC-MS/MS methods. A PK ‘trigger’ determined eligibility for the therapeutic expansion phase and was defined as unbound [infigratinib] &gt; 5-fold biochemical IC50 (i.e., 5 nM) in non-enhancing tumor. PD response was assessed by quantification of percentage of positive pERK, MIB-1, and Cleaved Caspase 3 cells in the surgical tissue compared to baseline archival/biopsy tissue. Patients with tumors exceeding the PK threshold for unbound drug concentration were eligible for expansion phase therapeutic dosing of infigratinib. Results: Seven patients were enrolled into the Phase 0 study with 3 patients who met the PK threshold continued to the expansion phase. In non-enhancing tumor region, the mean unbound concentration of infigratinib was 3.5 nM (n=7). The mean non-enhancing tumor-to-plasma coefficient for unbound drug (Kp,uu) was calculated to be 1.4. The suppression of pERK levels and MIB-1 levels was observed in 17% (1/6) and 67% (4/6) of the patients, respectively. At a median follow-up of 16.3 months [range: 2.8-18.7 months], the median progression-free survival (PFS) was 2.8 months (n=3). One patient remains on treatment. No grade 3+ toxicities were observed, and no adverse events resulted in discontinuation of therapy. Conclusions: Despite relatively high unbound tumor-to-plasma (Kp,uu) value, infigratinib achieves sub-optimal unbound drug concentration in the non-enhancing brain tumor tissue. Pharmacodynamic response with archival tissue as comparator did not reveal inhibition of pERK. Clinical trial information: NCT04424966 .

A phase 0/2 trigger trial of niraparib in patients with newly diagnosed glioblastoma.

2069 Background: Poly (ADP-ribose) polymerase (PARP) mediates DNA damage response; niraparib is an investigational PARP1/2-selective inhibitor. This Phase 0 study evaluates newly-diagnosed glioblastoma (GBM) tumor pharmacokinetics (PK) and pharmacodynamics (PD), graduating patients with O6-methylguanine methyltransferase (MGMT) unmethylated tumors into a therapeutic regimen of niraparib plus fractionated radiotherapy when high unbound drug concentrations are present in gadolinium-nonenhancing tumor. Methods: Patients with presumed newly-diagnosed GBM were enrolled in a phase 0 study receiving 4 days of niraparib (300/200 mg QD) prior to planned resection 3-5 or 8-12 hours following the last dose. Tumor tissue (enhancing and non-enhancing regions), cerebrospinal fluid (CSF), and plasma were collected. Total and unbound niraparib concentrations were measured using validated LC-MS/MS methods. PARP inhibition was assessed by quantification of PAR induction after 10 Gy ex vivo irradiation in surgical tissue compared to non-irradiated control tissue. A PK ‘trigger’ determined eligibility for the therapeutic expansion phase and was defined as unbound [niraparib] &gt; 5-fold biochemical IC50 (i.e., 19 nM) in non-enhancing tumor. Patients with MGMT unmethylated tumors exceeding this PK threshold were eligible for expansion phase dosing of niraparib plus radiotherapy followed by a maintenance phase of niraparib. Results: All patients (n=35) enrolled in the phase 0 portion of the study met the PK threshold. In non-enhancing tumor regions, the mean unbound concentration of niraparib was 253.2 nM in 32 evaluable GBM patients. The suppression of PAR levels after ex vivo radiation was observed in 75% of the patients (18/24). Eleven out of 18 patients with unmethylated tumors enrolled in phase 2. Five of the 6 initial patients enrolled in phase 2 experienced thrombocytopenia related to niraparib, and 3/5 cases were deemed serious and life-threatening. Consequently, starting dose in both phases was lowered to 200 mg, and no serious AEs were observed thereafter. At a median follow-up of 8.1 months [range: 6.0-12.9 months], PFS6 was 64% (n=11) with 4 patients remaining on treatment and 5 patients ongoing survival follow-up. Conclusions: Niraparib achieves pharmacologically-relevant concentrations in non-enhancing, newly-diagnosed GBM tissue in excess of any other studied PARP inhibitor. Clinical trial information: NCT05076513 .

Abstract 1507: Multiregional sampling of high grade glioma identifies regional biologic signatures

Abstract High grade gliomas (HGG) are aggressive primary brain malignancies typified by diffuse invasion, genetic heterogeneity, and a universally fatal outcome. MRI-defined contrast-enhancing (CE) tumor burden serves as the clinical standard that guides maximal surgical resection and post-therapy response assessment. However, HGGs also comprise an invasive non-enhancing (NE) tumor margin that extends beyond the CE core and harbors the cells that contribute to recurrence. Sampling restrictions have hindered the comprehensive study of these NE HGG cell populations driving tumor progression. Herein, we present an integrated multi-omic analysis of 313 spatially matched multi-regional CE and NE tumor biopsies from 68 HGG patients, performing whole exome and RNA sequencing of both IDH wild-type and IDH mutant HGGs. We report spatially restricted molecular profiles in IDH-mutant HGG, highlighting a concern for sampling bias given the importance of molecular diagnosis and prognostication in IDH-mutant HGG. Regardless of IDH status, we found that NE tumor regions harbored the highest proportion of private mutations, which reflects an increased development of regional genomic complexity in infiltrative tumor. The multiregional genomic profiling of our IDH wild-type HGG cohort reveals that EGFR and NF1 somatic alterations occur as mutually exclusive events in 98.7% of tumors. However, we resolved rare low allele frequency co-alterations of EGFR and NF1 within the NE region. We find this co-occurrence enriched in recurrent tumors, pointing to the early emergence of NF1 inactivation in the NE regions. We constructed genomic models predictive of recurrent disease from both NE and CE regions, which highlight the occurrence of clonal EGFR copy number alterations and NF1 loss as clonal or subclonal events, respectively, emphasizing the regional and temporal complexity of well-studied canonical driver alterations. We detailed the spatially unique acquisition of multiple distinct EGFR alterations giving rise to intra-tumoral EGFR mosaicism, a challenge in the implementation of EGFR directed therapies. Our study also identified two transcriptomic clusters delineated by the significant overrepresentation of neuronal (NEU) and glycolytic/plurimetabolic (GPM) pathway-based functional states in the NE region. NE regions of the NEU subtype harbor the greatest proportion of private mutations, suggesting these infiltrative tumor cells accumulate alterations without clonal expansion. GPM populations conversely displayed a less branched phylogeny and were transcriptionally enriched in immune cell signatures. This phenotypic dichotomy between GPM and NEU populations supports the growing body of evidence that invasive GBM cells either take on a neuronal phenotype for active invasion or a more metabolic phenotype involving interaction with astrocytes, other glial cells, and infiltrating immune cells. Citation Format: Mylan R. Blomquist, Leland S. Hu, Fulvio D'Angelo, Taylor M. Weiskittel, Francesca P. Caruso, Shannon P. Fortin Ensign, Christopher Sereduk, Gustavo De Leon, Lee Curtin, Javier Urcuyo, Ashlynn Gonzalez, Ashley Nespodzany, Teresa Noviello, Jennifer M. Eschbacher, Kris A. Smith, Peter Nakaji, Bernard R. Bendok, Richard S. Zimmerman, Chandan Krishna, Devi Patra, Naresh Patel, Mark Lyons, Kliment Donev, Maciej Mrugala, Alyx Porter, Anna Lasorella, Kristin R. Swanson, Michele Ceccarelli, Antonio Iavarone, Nhan L. Tran. Multiregional sampling of high grade glioma identifies regional biologic signatures [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 1507.

Aneurysm wall enhancement, hemodynamics, and morphology of intracranial fusiform aneurysms.

Intracranial fusiform aneurysms (IFAs) are considered to have a complex pathophysiology process and poor natural history. The purpose of this study was to investigate the pathophysiological mechanisms of IFAs based on the characteristics of aneurysm wall enhancement (AWE), hemodynamics, and morphology. A total of 21 patients with 21 IFAs (seven fusiform types, seven dolichoectatic types, and seven transitional types) were included in this study. Morphological parameters of IFAs were measured from the vascular model, including the maximum diameter (Dmax), maximum length (Lmax), and centerline curvature and torsion of fusiform aneurysms. The three-dimensional (3D) distribution of AWE in IFAs was obtained based on high-resolution magnetic resonance imaging (HR-MRI). Hemodynamic parameters including time-averaged wall shear stress (TAWSS), oscillatory shear index (OSI), gradient oscillatory number (GON), and relative residence time (RRT) were extracted by computational fluid dynamics (CFD) analysis of the vascular model, and the relationship between these parameters and AWE was investigated. The results showed that Dmax (p = 0.007), Lmax (p = 0.022), enhancement area (p = 0.002), and proportion of enhancement area (p = 0.006) were significantly different among three IFA types, and the transitional type had the largest Dmax, Lmax, and enhancement area. Compared with the non-enhanced regions of IFAs, the enhanced regions had lower TAWSS but higher OSI, GON, and RRT (p < 0.001). Furthermore, Spearman's correlation analysis showed that AWE was negatively correlated with TAWSS, but positively correlated with OSI, GON, and RRT. There were significant differences in AWE distributions and morphological features among the three IFA types. Additionally, AWE was positively associated with the aneurysm size, OSI, GON, and RRT, while negatively correlated with TAWSS. However, the underlying pathological mechanism of the three fusiform aneurysm types needs to be further studied.

Differentiation of Pilocytic Astrocytoma from Glioblastoma using a Machine-Learning framework based upon quantitative T1 perfusion MRI

Background and purposeDifferentiation of pilocytic astrocytoma (PA) from glioblastoma is difficult using conventional MRI parameters. The purpose of this study was to differentiate these two similar in appearance tumors using quantitative T1 perfusion MRI parameters combined under a machine learning framework. Materials and methodsThis retrospective study included age/sex and location matched 26 PA and 33 glioblastoma patients with tumor histopathological characterization performed using WHO 2016 classification. Multi-parametric MRI data were acquired at 3 T scanner and included T1 perfusion and DWI data along with conventional MRI images. Analysis of T1 perfusion data using a leaky-tracer-kinetic-model, first-pass-model and piecewise-linear-model resulted in multiple quantitative parameters. ADC maps were also computed from DWI data. Tumors were segmented into sub-components such as enhancing and non-enhancing regions, edema and necrotic/cystic regions using T1 perfusion parameters. Enhancing and non-enhancing regions were combined and used as an ROI. A support-vector-machine classifier was developed for the classification of PA versus glioblastoma using T1 perfusion MRI parameters/features. The feature set was optimized using a random-forest based algorithm. Classification was also performed between the two tumor types using the ADC parameter. ResultsT1 perfusion parameter values were significantly different between the two groups. The combination of T1 perfusion parameters classified tumors more accurately with a cross validated error of 9.80% against that of ADC's 17.65% error. ConclusionThe approach of using quantitative T1 perfusion parameters based upon a support-vector-machine classifier reliably differentiated PA from glioblastoma and performed better classification than ADC.