Huang, Jiayi

Abstract Purpose: Standard care for high-grade gliomas (HGG) involves maximal surgical resection followed by radiation and temozolomide. Postoperative adjuvant therapy frequently causes lymphopenia, which is associated with poor prognosis. Interleukin 7 (IL7) is essential for lymphocyte development, homeostasis, and survival. NT-I7 (efineptakin alfa), a long-acting recombinant IL7, reverses lymphopenia and improves survival in murine glioma models. However, the safety, maximum tolerated dose (MTD), and impact of NT-I7 on immune cells in patients with HGG remain unknown. Patients and Methods: We conducted a phase I trial (NCT03687957) examining the MTD and effect of NT-I7 on lymphocytes in patients with newly diagnosed HGG. The primary endpoint was dose-limiting toxicity; secondary endpoints included absolute lymphocyte count (ALC) changes over time, overall response, progression-free survival, and overall survival. Exploratory endpoints included immune profiling at different time points using single-cell RNA sequencing (scRNA-seq) in a subset of patients. Results: NT-I7 was well tolerated with a MTD of 720 µg/kg. Moreover, NT-I7 significantly increased ALCs for more than 12 weeks in duration. Early elevations in CD4+, CD8+ T cells and NK cells further coincided with increased TNF and CXCL9 cytokine levels. Comprehensive immune profiling of peripheral blood T cells revealed selective clonotype expansion within CD8+, but not CD4+, T cells following NT-I7 administration. Finally, a subset of our patients with MGMT promoter–unmethylated glioblastoma, which are typically associated with a poorer prognosis, demonstrated promising clinical responses. Conclusions: NT-I7 has the potential to maintain and increase lymphocyte counts in patients with HGG and warrants further investigation, particularly in combination with immune-based therapies.

Abstract BACKGROUND Lymphopenia, a common finding in patients with high-grade gliomas (HGGs), is associated with poor outcomes including worse survival, fatigue, and in some cases, increased opportunistic infections. Interleukin-7 (IL-7) is a cytokine crucial for lymphocyte survival and proliferation. We previously demonstrated long-acting IL-7 (rhIL-7-hyFc, efineptakin alfa, NT-I7) increases absolute lymphocyte counts (ALCs) and extends survival in preclinical murine models of HGG. Here, we report results using rhIL-7-hyFc to effectively reduce lymphopenia in patients with HGG. METHODS We performed a phase II randomized, placebo-controlled, double-blind study of rhIL-7-hyFc in patients with newly diagnosed HGGs (82% IDH-wildtype glioblastoma in both groups). Patients received rhIL-7-hyFc (720mcg/kg) or placebo one-week post-radiation and temozolomide, with subsequent doses at weeks 13, 25, and 37. The primary endpoint was ALC four weeks post-initial administration; exploratory endpoints included CD4 count, progression-free survival (PFS), and overall survival (OS). RESULTS We enrolled 22 patients (median age 59.5 years, range 33-74; 40.9% female) with HGG. Both groups exhibited comparable demographics, including MGMT methylation status, and received a median of 2 doses of rhIL-7-hyFc or placebo. At 4 weeks, the pre-specified primary endpoint, ALC significantly increased relative to baseline in the treatment group, compared to placebo (median percent change=148% vs. 16.7%, p=0.007), as did CD4 count (121% vs. 10.5%, p=0.011). There were no treatment-related grade 4/5 adverse events. Exploratory endpoints of PFS and OS will be reported at time of conference. CONCLUSIONS rhIL-7-hyFc is safe and effective in improving ALC and CD4 count in patients with newly diagnosed HGG undergoing temozolomide and concurrent radiation therapy. This study was powered to meet the primary endpoint; larger trials will likely be required to demonstrate clinical efficacy. Nevertheless, these data support the continued exploration of rhIL-7-hyFc as an adjunct to standard therapy to mitigate lymphopenia and potentially extend survival for patients with HGG.

Abstract INTRODUCTION Immunotherapy has not improved survival in recurrent GBM (rGBM). Indoleamine 2,3 dioxygenase 1 (IDO1), highly expressed in ~90% of patients with malignant glioma, is a rate-limiting enzyme that catabolizes tryptophan (Trp) into kynurenine (Kyn) and enables immune escape. METHODS We hypothesized combining therapies targeting immunosuppressive pathways with cytotoxic and antiangiogenic therapies would overcome tumor-related immunosuppression. This was an open-label Phase II study of two regimens: Arm A consisted of retifanlimab (anti-PD1, 500mg IV Q4W) + bevacizumab (10mg/kg IV Q2W) + HFRT (3.5Gy/day x 10) in patients with IDH1/2-WT rGBM. Regimen B added the IDO inhibitor, epacadostat (400mg po BID), initiated prior to HFRT. Key inclusion criteria included dexamethasone ≤ 4 mg/day. The primary endpoint was overall survival (OS) at 9 months (OS-9). 24 evaluable patients were required to detect an OS-9 of 60% with 80% power, compared to 38% in historical controls (bevacizumab alone) by 1-sided 1-sample log rank test at alpha=0.1. RESULTS We previously reported Arm A. Here, we present results from Arm B. 25 of the 27 patients enrolled to regimen B were evaluable: median age 58years (23-71); 28% female; 23% MGMT promotor methylated; median KPS 90 (70 - 100); a median of 6 cycles of epacadostat as of May 2024 (1 - 13). 18 of 25 died with a median follow up 9.23 months. Median PFS was 7.52 months (95%CI: 5.52-9.43). Median OS was 9.5 months (95%CI 8.08-11.96). Regimen B met its primary endpoint with OS-9 of 61.07% (95%CI: 38.23-77.65%). There were 5 possible immune-related grade 3+ toxicities to date (2 ALT/AST increase; 3 rash). CONCLUSIONS Retifanlimab, epacadostat, HFRT, and bevacizumab in rGBM is well-tolerated, with encouraging OS and PFS at the time of submission. Arm B met its primary endpoint. Further studies are warranted to identify biomarkers to predict long-term responders.

2015 Background: Effective treatments for recurrent meningiomas following radiation therapy (RT) are limited. Inhibitors of the programmed-death-1 (PD-1) or programmed-death ligand-1 (PD-L1) pathway have shown modest activity for these tumors in single-arm phase 2 studies. This study aims to evaluate the immunological effects of combining anti-PD-L1 (avelumab) with proton beam therapy (PBT) for recurrent radiation-relapsed meningiomas. Methods: Recurrent grade 1-3 meningiomas that failed prior surgery and RT were treated with neoadjuvant avelumab (10 mg/kg IV biweekly for 6 doses) plus hypofractionated PBT (20 Gy over 5 fractions), followed by surgery and additional adjuvant avelumab (up to 6 doses). Blood samples were collected pre-avelumab, at week 4, and before surgery. Eligibility criteria include age ≥ 18 years, KPS ≥ 60, surgery suitability, dexamethasone dose ≤ 4mg daily, normal organ function; no prior anti-PD1/PDL1 therapy, and absence of autoimmunity. RNA-sequencing (RNAseq) and multiplex immunofluorescence (MxIF) were performed on pre- and post-avelumab tumor tissues; blood samples underwent multiplex flow cytometry (MxFC). Results: Between March 2018 to March 2023, 9 patients (22% grade 1, 56% grade 2, and 22% grade 3) were enrolled in the study. All completed neoadjuvant therapy, one forwent surgery due to dramatic radiological response, and two did not complete adjuvant avelumab (due to patient preference and infusion reaction). There was no dose-limiting toxicity or unexpected toxicity. After a median follow-up of 43.0 month and a minimum follow-up of 21.7 months, 8 patients have progressed, and 2 patients with progression have died. The median progression-free survival (PFS) was 19.1 months (95% CI: 15.2-23.0), with the median overall survival not yet reached. Three patients demonstrated notably prolonged PFS (37.7, 58.5 months, and ongoing). RNAseq showed significant increase in T-cell and macrophage gene expression in post-treatment tissues compared to pre-treatment. MxIF revealed a marked increase in T-cell and CD68+ macrophage infiltration in the long-PFS patients’ post-treatment tissues, a pattern not observed in the short-PFS patients. Particularly, the long-PFS patients’ post-treatment tissues displayed increased infiltration of CD68+HLADR+ macrophages, likely of M1-phenotype. In contrast, the pre- and post-treatment tissues from the short-PFS patients predominantly featured CD206+ macrophages, likely of M2-phenotype. A trend towards increased number of primed T cells in the peripheral blood was observed in the long-PFS patients at week 4. Conclusions: Avelumab combined with RT may induce an immunological response in some radiation-relapsed meningioma patients, leading to prolonged remission. Further investigations with larger prospective studies and predictive biomarkers are warranted. Clinical trial information: NCT03267836 .

Abstract RTOG 9402 demonstrated procarbazine (P), lomustine (CCNU/C), and vincristine (V), collectively PCV, added to radiation therapy significantly improved survival for patients with newly diagnosed anaplastic oligodendroglial tumors. The improvement was most pronounced in 1p19q codeleted cases, and to a lesser extent, IDH-mutant cases, with no survival benefit in cases with neither biomarker. Analogous results were observed in other phase III trials. However, vincristine (V) can cause substantial toxicity and requires intravenous administration, both negatively affecting quality of life, with debatable contribution to PCV efficacy. As a randomized trial comparing PCV to PC is unlikely to be conducted, we explored correlations between survival and V-dosing in patients randomized to PCV in RTOG 9402. We performed post-hoc analyses of all evaluable participants (n = 143) randomized to PCV on RTOG 9402, supplemented by restricting the analyses to the chemosensitive molecular subsets (IDH-mutant and/or 1p/19q codeleted, n = 118). Total V dose by quartile (Q) was calculated. Survival from six months post-randomization was compared among V dose groups, adjusting for age, extent of resection (EOR), and Karnofsky Performances Status (KPS) in a Cox proportional hazards model. Higher V dose received correlated with longer survival in multivariate analyses (n = 134, median-Q3 vs. < Q1, HR 0.40 (0.22, 0.73), p = 0.003; ≥Q3 vs. < Q1, HR 0.39 (0.22, 0.72), p = 0.002). Excluding chemoresistant cases (IDH wild-type/not codeleted), survival was also significantly longer in evaluable participants receiving the highest doses of vincristine (≥Q3 vs. < Q1 HR 0.42 (0.21,0.81), p = 0.01). In this post-hoc analysis, higher overall V-dose received correlated with longer survival in evaluable patients with anaplastic oligodendroglial tumors receiving PCV chemotherapy in RTOG 9402. Of note, as vincristine dosing was not assigned by randomization, confounding due to differences in patient characteristics among V dose groups cannot be ruled out. Caution should be exercised when considering discarding V from the PCV regimen.

Abstract BACKGROUND Differentiating radiation necrosis from tumour progression after radiation therapy (RT) for brain metastases (BM) remains clinically challenging, and accurate imaging is crucial to prevent unnecessary surgery or unwarranted changes in therapy. 18F-Fluciclovine is a PET radiopharmaceutical with low background uptake in the brain and increased uptake in BM. The PURSUE study (NCT04410367) aimed to establish image interpretation criteria (IIC) for detecting suspected recurrent BM after RT using 18F-fluciclovine PET, based on several measures of lesion uptake. MATERIAL AND METHODS Across 7 US sites, 23 patients with solid tumour BM and a previously irradiated ‘reference’ lesion equivocal for recurrence on MRI who were scheduled for craniotomy underwent 18F-fluciclovine PET (185 MBq) <42 days post-MRI and 1-21 days pre-craniotomy. Three independent, blinded readers qualitatively rated lesion 18F-fluciclovine uptake as ‘mild’ (up to blood pool), ‘moderate’ (above blood pool to parotid gland), or ‘marked’ (above parotid gland). The primary endpoint was the diagnostic performance of different thresholds of lesion uptake on qualitative (visual) reads vs central histopathology. Secondary endpoints included diagnostic performance, based on different thresholds, of quantitative (e.g., lesion standardized uptake value [SUV]), and dynamic measures. A committee, including two independent imaging physicians, reviewed all data to establish the IIC, which were subsequently used to evaluate the diagnostic performance of 18F-fluciclovine. RESULTS All 23 reference lesions underwent histopathological analysis, with 10 (43%) being pathologically confirmed BM recurrence. The highest performing qualitative measure of 18F-fluciclovine lesion uptake was ‘marked’, rendering 92-100% and variable (40-80%) across readers. SUVmax was a reader-independent, high-performing quantitative metric (AUC 0.87, SUVmax threshold 4.8, 80% sensitivity, 85% specificity). Dynamic measures did not add diagnostic value. Thus, the committee established IIC as: "Lesions with 18F-fluciclovine uptake of a SUVmax equal to or greater than 4.8, or visually greater than the parotid gland, should be considered suspicious for recurrence. Otherwise, recurrence should be considered unlikely." Application of these IIC resulted in 80% sensitivity, 77-85% specificity, 73-80% positive predictive value, and 83-85% negative predictive value across readers. CONCLUSION PURSUE is the first prospective, multicentre study to define IIC for 18F-fluciclovine PET for accurate identification of suspected recurrent BM after RT, verified by histopathology. In this initial cohort, the IIC convey excellent diagnostic performance for 18F-fluciclovine and will help evaluate 18F-fluciclovine PET in future studies. This study was sponsored by Blue Earth Diagnostics Ltd.

Abstract BACKGROUND After radiation therapy (RT) for brain metastases (BM), differentiating radiation necrosis from tumor recurrence remains challenging. PURSUE (NCT04410367) evaluated various measures of lesion 18F-fluciclovine uptake to establish image interpretation criteria (IIC) for 18F-fluciclovine-PET to accurately diagnose recurrent BM. METHODS Patients with solid tumor BM and a previously irradiated ‘reference’ lesion equivocal for recurrence on MRI who were scheduled for craniotomy underwent 18F-fluciclovine-PET (185 MBq) <42 days post-MRI and 1-21 days pre-craniotomy. Lesion 18F-fluciclovine uptake was qualitatively rated as ‘mild’ (up to blood pool), ‘moderate’ (above blood pool to parotid gland), or ‘marked’ (above parotid gland) by three independent blinded readers. The primary endpoint was diagnostic performance of different uptake thresholds on qualitative reads vs central histopathology. Secondary endpoints included diagnostic performance, based on different thresholds, of quantitative (e.g., lesion standardized uptake value [SUV]) and dynamic measures. IIC were determined by committee and subsequently used to assess the diagnostic performance of 18F-fluciclovine. RESULTS All 23 reference lesions from 23 enrolled patients underwent histopathological analysis; 10 (43%) were pathologically-confirmed BM recurrence. The highest performing qualitative measure was ‘marked’, rendering 92-100% sensitivity and 40-80% specificity across readers. SUVmax was a reader-independent, high-performing quantitative metric (AUC 0.87, SUVmax threshold 4.8, 80% sensitivity, 85% specificity). Dynamic measures did not add diagnostic value. Thus, IIC was established as: “Lesions with 18F-fluciclovine uptake of SUVmax equal to or greater than 4.8, or visually greater than the parotid gland, should be considered suspicious for recurrence. Otherwise, recurrence should be considered unlikely.” Application of the IIC resulted in 80% sensitivity, 77-85% specificity, 73-80% PPV, and 83-85% NPV across the readers. CONCLUSIONS PURSUE is the first prospective, multicenter trial to establish IIC for 18F-fluciclovine-PET for suspected recurrent BM after RT, verified by histopathology. Finalized IIC demonstrated excellent diagnostic performance for 18F-fluciclovine and will help evaluate 18F-fluciclovine-PET in future studies.

2001 Background: Differentiating radiation necrosis from tumor progression remains one of the most commonly encountered and clinically challenging scenarios after radiation therapy (RT) for brain metastases (BM). PURSUE (NCT04410367) evaluated the diagnostic performance of 18F-fluciclovine, an amino acid PET radiopharmaceutical, based on various lesion metrics, to establish image interpretation criteria (IIC) for suspected recurrent BM after RT. Methods: Patients with solid tumor BM were enrolled across 7 US sites if they had a previously irradiated ‘reference’ lesion equivocal on MRI for recurrence and were planned for craniotomy. 18F-Fluciclovine PET (185 MBq) took place <42 days post-MRI and 1-21 days pre-craniotomy. The primary endpoint was the diagnostic performance (sensitivity, specificity, positive-, and negative-predictive value [PPV/NPV]) of different thresholds of lesion 18F-fluciclovine uptake on qualitative, visual reads vs central histopathological analysis. Lesion 18F-fluciclovine uptake was assessed qualitatively by 3 independent blinded readers who visually rated the uptake as ‘mild’ (up to blood pool), ‘moderate’ (above blood pool to parotid), or ‘marked’ (above parotid). Secondary endpoints included the diagnostic performance based on different thresholds of quantitative (e.g., lesion SUV) and dynamic measures of uptake. A committee, including 2 expert imaging physicians independent to PURSUE, reviewed all data in round-table meetings to establish the IIC, which were subsequently used to assess diagnostic performance. Results: All 23 reference lesions in 23 subjects underwent histopathological analysis, with 10 (43%) confirmed as recurrent tumor. The highest performing qualitative measure was ‘marked’, rendering a sensitivity of 92-100%, with variable specificity of 40-80% across readers. SUVmax was a reader-independent, high-performing quantitative metric on ROC analysis (AUC 0.87, SUVmax threshold 4.8 conferring a sensitivity of 80% and specificity of 85%). Dynamic measures did not provide added diagnostic value. After analyzing these metrics, the committee established IIC as: Lesions with 18F-fluciclovine uptake of a SUVmax equal to or greater than 4.8, or visually greater than the parotid gland, should be considered suspicious for recurrence. Otherwise, recurrence should be considered unlikely. Application of the IIC resulted in a sensitivity of 80%, specificity of 77-85%, PPV of 73-80%, and NPV of 83-85% across the readers. Conclusions: This is the first prospective multicenter trial to evaluate PET characteristics of suspected recurrent BM after RT, verified by histopathology. Qualitative and quantitative IIC show 18F-fluciclovine to be a high-performing diagnostic tool. These IIC will help evaluate the diagnostic performance of 18F-fluciclovine PET in future trials. Clinical trial information: NCT04410367 .

Abstract INTRODUCTION Immunotherapies targeting PD-1 in recurrent glioblastoma (rGBM) have shown limited activity. We hypothesize combining therapies targeting immunosuppressive pathways with cytotoxic and antiangiogenic therapies will improve survival. This nonrandomized, noncomparative Phase II study examines safety and efficacy of an anti-PD-1 monoclonal antibody (retifanlimab), hypofractionated radiotherapy (HFRT), and bevacizumab, with or without an IDO1 inhibitor (epacadostat), in patients with rGBM. METHODS This is an open-label Phase II study of two regimens. Regimen A examines retifanlimab (500mg IV Q4W) + bevacizumab (10mg/kg IV Q2W) + HFRT (3.5Gy/day x 10) in patients with IDH1/2-WT rGBM. Regimen B adds epacadostat. Key inclusions include dexamethasone ≤ 4 mg/day and reirradiation candidacy. The primary endpoint is overall survival (OS) probability at 9 months (OS-9). An increase of OS-9 from 38% (bevacizumab alone) to 60% was considered clinically relevant and required 24 efficacy evaluable patients. RESULTS Regimen A accrual is complete; interim results are as follows: 26 rGBM enrolled, with 24 evaluable [median age 64.2 years (42.1-81.8); 29% female; 29% MGMT promotor methylated; 33.3% with multi-focal disease; median KPS 90 (70-100); median baseline dexamethasone 0 mg (0-4) and ALC 1,000 cells/µl (300-3,700)]. Patients received a median of 6 cycles as of May 2022 (2-24). Median follow-up is 16.0 months. Interim median PFS is 7.0 months (95%CI: 4.5~11.1) and median OS is 12.2 months (95%CI 7.1~18.0). Regimen A met primary endpoint with OS-9 of 67% (95%CI: 44~82%). Overall response rate is currently 58% (95%CI: 36.94~77.2%). There were five possible immune-related grade 3+ toxicities to date (n = 1 each colitis, vomiting, and seizure; n = 2 diarrhea). Regimen B is enrolling. CONCLUSIONS Interim analysis suggests combination retifanlimab, HFRT, and bevacizumab in rGBM is generally well-tolerated, with encouraging OS and PFS at the time of submission. Correlative analysis is ongoing and will be presented at the meeting.

Abstract BACKGROUND Radiation Therapy Oncology Group 9802 was a phase III trial for patients with centrally confirmed LGG (WHO grade II). Participants ³ 40 years or those with neurosurgeon defined less than gross total resection (GTR) were randomized to radiotherapy (RT) +/- PCV. In a separate cohort, adults age &lt; 40 years with neurosurgeon defined GTR were observed by MRI every 6 months without adjuvant therapy. At last report, outcome for the observation cohort was immature with median follow-up of only 4.4 years. Here, we present mature outcomes for the observation arm. METHODS Eligible adults (as above) were observed by MRI every 6 months. OS and PFS were estimated by Kaplan-Meier method and estimated hazard ratios to characterize the prognostic variables. RESULTS There were 111 eligible patients (median age 30; median KPS = 100). Median follow-up was 16.1 years with 71 (64%) alive at the last follow-up. 79 patients (71%) had progressed with median PFS of 6.9 years. 5, 10, and 15 year-PFS and OS rates were 54%, 39%, 28% and 94%, 77%, and 65%. 1p19q status was codeleted in 32%, IDH1/2 mutant in 78% and MGMT promoter methylated in 39% of tested cases. Multivariate Cox analyses showed that preoperative tumor size ³ 4 cm (HR = 2.43 for PFS, p = 0.001; HR = 2.58 for death, p = 0.016) and residual disease on imaging ³ 1 cm (HR = 2.97 for PFS, P &lt; 0.001; HR = 2.02 for death, p = 0.05) were associated with worse outcomes. Analyses based on molecular results will be presented. CONCLUSION A subset of low-grade gliomas can be observed after the initial resection based on younger age, smaller tumor size, and no residual disease on neuroimaging. This can likely be further refined by prognostic molecular markers. Patients with the most favorable prognostic factors can avoid or delay the acute and long-term side effects of RT and chemotherapy for several years.