Johanns, Tanner M.

Introduction Approximately 50% of patients with uveal melanoma develop metastatic disease, most commonly involving the liver, and prognosis remains poor. Immunoembolization (IE) is an established liver-directed therapy for patients with liver-dominant metastatic uveal melanoma (mUM), though comparative data with other regional therapies remain limited. We present a single-center retrospective analysis of IE in hepatic mUM and compare outcomes with those reported in the Phase 3 FOCUS trial evaluating melphalan via percutaneous hepatic perfusion. Methods All patients with liver-dominant mUM treated with IE between 2010 and 2023 at our institution were included. Clinical records were reviewed for demographics, tumor characteristics, treatment details, and outcomes. The primary endpoint was disease control rate (DCR), defined as complete response (CR), partial response (PR), or stable disease (SD). Secondary endpoints included progression-free survival (PFS) and overall survival (OS), with subgroup analyses based on prior systemic therapy exposure. Descriptive statistics were used for analysis. Results Forty-three patients (62.8% female; median age 62 years; all Caucasian) underwent 249 IE procedures (mean 5.8 procedures per patient) over a median treatment duration of 9.1 months. Choroidal primaries accounted for 95.3% of cases, and 90.7% had liver-only metastases. The overall DCR was 27.9% (CR 4.7%, PR 20.9%, SD 2.3%), while 62.8% experienced disease progression. Median PFS was 0.85 months, and median OS was 32.7 months. One- and two-year OS rates were 69.8% and 55.8%, respectively. In subgroup analysis, patients who had received prior systemic therapy (n=12) demonstrated improved outcomes compared with treatment-naïve patients, with longer median PFS (29.9 vs. 7.2 months) and higher 2-year OS (60.0% vs. 47.0%). Compared with outcomes reported in the FOCUS trial, IE demonstrated shorter median PFS (0.85 vs. 9.0 months) and lower DCR (27.9% vs. 73.6%), but longer median OS (32.7 vs. 20.5 months). Discussion IE produced overall survival outcomes comparable to hepatic melphalan delivery despite lower radiographic response rates. Notably, patients previously treated with systemic therapy experienced improved outcomes, suggesting a potential sequencing effect. These findings support IE as a viable liver-directed therapy for liver-dominant mUM. Prospective, multicenter trials are warranted to clarify optimal sequencing strategies and enhance therapeutic outcomes.

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 Glioblastoma is a highly lethal malignancy with dismal overall survival and near universal recurrence despite maximal multimodal therapy. Patients with unmethylated O6-methylguanine methyltransferase (MGMT) promoters do not derive survival benefit from adjuvant temozolomide. Immunotherapies have revolutionized cancer care; however, this modality has yet to translate into survival benefits in glioblastoma in part due to both local and systemic immunosuppressive states. Here, we report the results of a phase 1 clinical trial (NCT04015700) evaluating the safety and feasibility of GNOS-PV01, a personalized DNA vaccination platform that safely immunized against up to 40 patient-specific neoantigens in a clinically relevant timescale following surgical resection and radiation for MGMT-unmethylated glioblastoma patients. Multisector tumor sampling at time of resection enabled personalized and spatially representative neoantigen identification through an established pipeline. In the nine participants receiving vaccines, there were no unexpected toxicities or serious adverse events with a median vaccine delivery time of 10 weeks post-radiation. The vaccination was strongly immunogenic and induced activation and expansion of both local infiltrating CD8+ and CD4+ T-cells and circulating peripheral T-cells. T-cell receptor sequencing revealed both expanded pre-existing populations as well as novel neoantigen-specific populations, suggesting that vaccination both reinvigorates pre-existing immunity and generates novel immune reactivity. We developed a new technology to profile T-cells at single-nuclei resolution from frozen tissue revealing that vaccination altered gene expression signatures involved in inflammatory response and lymphocyte activation in the tumor microenvironment. Exposure to dexamethasone greatly suppressed immune reactivity, while PD-1 blockade enhanced local immune responses. With respect to efficacy, one third of patients survived longer than 24 months with one long-term survivor living >40 months from time of diagnosis, exceeding survival of recently published trials. Thus, our study demonstrates the safety, feasibility, and preliminary clinical efficacy of a personalized multivalent neoantigen vaccination platform in a devastating cancer.

e21600 Background: Uveal melanoma (UM), the most common intraocular malignancy in the U.S., metastasizes in 50% of patients, frequently to the liver (~90%) with poor prognosis (median overall survival [mOS] 1 year). Metastatic UM (mUM) literature is limited (due to its rarity/complexity) and management remains challenging, as standard therapies—liver-directed approaches (e.g. transarterial chemoembolization [TACE]) and systemic therapy with tebentafusp (limited to HLA-A*02:01-positivity)—offer limited efficacy, with no durable responses or significant survival benefits. Interestingly, Delcath’s recent FOCUS Phase 3 trial demonstrated the efficacy of the melphalan/Hepatic Delivery System for unresectable mUM, with an objective response rate (ORR) of 36.3%, 1-year OS of 80%, and median progression-free survival (PFS) of 9 months. Here, we present a large retrospective study of liver-predominant mUM treated with immunoembolization (IE) at a tertiary academic center. This study provides valuable data to the underreported mUM literature. We also compare our findings with Delcath’s trial to contextualize results and identify clinical factors influencing treatment response and prognosis. Methods: We retrospectively reviewed charts of mUM patients treated with IE (age ≥18 years, 2010–2023). Data collected included demographics, clinical/pathology/molecular details, and management/outcomes. Subgroup analysis on prior systemic therapy use was performed (similar to Delcath). The primary outcome was OS at 12 and 24 months. Results: 43 patients were included (100% White, 62.8% female, median age 62). Most had choroidal type (95.3%), hepatic-only metastases (90.7%), and were treatment-naïve before IE (72.1%). Across 249 IE procedures (5.8 per patient, mean duration 9.1 months), we observed median PFS and OS of 9.2 and 23 months, respectively - comparable to Delcath’s trial (9 and 20.5 months). Despite higher disease progression in our study (62.8% vs. 25.3%) and lower best clinical response (27.9% vs. 73.7%), 1-year (67% vs. 80%) and 2-year OS rates (49% vs. 43%) were similar. Subgroup analysis revealed better outcomes in previously treated patients (n = 12) compared to treatment-naïve patients (n = 31), with improved median PFS (29.9 vs. 7.2 months) and 1- and 2-year OS (75% vs. 65% and 58.3% vs. 41.9%, respectively). This contrasts with Delcath’s findings, where prior therapy did not significantly affect PFS or OS. Median PFS was comparable in treatment-naïve groups (7.2 vs. 9 months) but markedly improved in our previously treated group (29.9 vs. 9.2 months). Conclusions: We highlight IE’s comparable efficacy to Delcath’s melphalan/Hepatic Delivery System regarding mUM PFS and OS, with added benefits for previously treated patients. While our findings advance understanding of mUM management, more prospective studies are needed to improve therapeutic strategies/patient outcomes.

5069 Background: Ra-223 improves the overall survival in patients with mCRPC to the bone. We assessed the safety of standard-of-care Ra-223 in combination with peposertib, a DNA-dependent protein kinase inhibitor, with or without avelumab, an anti-PD-L1 antibody. Methods: Patients with mCRPC and two or more skeletal metastases identified by bone scintigraphy with or without lymph node metastases up to 3 cm in size, but no visceral metastases, were eligible. Progression after progression after at least one androgen receptor pathway inhibitor or taxane was required. Phase 1 consisted of a two-step sequential safety lead-in using a 3+3 design. Step 1 combined 6 standard cycles of Ra-223 (55 kBq/kg), with increasing doses of peposertib: 50, 100, and 200 mg PO bid on days 3-26 of each cycle. Step 2 combined Ra-223 with the maximum tolerated dose of peposertib and added standard avelumab 800 mg IV every 14 days, starting at cycle 2 of Ra-223. Results: A total of 9 patients participated in Step 1, where the maximum tolerated peposertib dose of 200 mg PO bid with Ra-223 was deemed tolerable. A total of 6 patients participated in Step 2 and the combination of Ra-223, peposertib at 200 mg PO bid, and standard avelumab was deemed tolerable. Of the 15 patients in Phase 1, none experienced grade 4 or higher treatment-related toxicities, while 7 experienced grade 3 toxicities, including neutropenia (1), anemia (1), cardiac chest pain (1), fall (1), maculopapular rash (2), and lymphopenia (2). The median (Q1, Q3) PSA velocity from the beginning to the end of treatment was lower for Step 2 versus Step 1: 2.1 (-0.1, 4.6) versus 23.5 (18.6, 77.1) ng/mL/month (p = 0.0067). OS and PFS were calculated with the limitation that the Phase 1 was non-randomized. Median OS was not reached for Step 2, as only 1 of 6 patients had died, versus 15.2 months for Step 1, where 8 out of 9 patients had died (p = 0.0537). The patient who died in Step 2 discontinued therapy prematurely after 3 cycles due to progression and survived 15.2 months (the 5 alive completed all 6 cycles). The median radiographic PFS was 7 months for Step 2 versus 12.7 months for Step 1 (p = 0.8910). Conclusions: The combination of Ra-223 and peposertib, with or without avelumab was well tolerated. The triplet combination showed the most promising results at this early evaluation. We continue to accrue in the randomized Phase II portion of the trial. Clinical trial information: NCT04071236 .

Abstract Lymphopenia following chemoradiation for high grade gliomas (HGG) is common and is associated with decreased survival. NT-I7 (efineptakin alfa) is a long-acting analog of the lymphocyte pro-survival cytokine, interleukin-7. Our Phase I dose-escalation study of 19 patients with HGG demonstrated early elevations in CD4+ and CD8+ T cells in the first 4 weeks after administration of NT-I7. In this study, we explored the diversity and potential functionality of the NT-I7-expanded T cell population. A subset of 4 subjects with glioblastoma multiforme (GBM) treated at 720 µg/kg of NT-I7 during adjuvant temozolomide in our study (NCT03687957) underwent Cellular Indexing of Transcriptomes and Epitopes by Sequencing (CITE-seq) of peripheral blood. CITE-seq with TCR clonotype sequencing (10x Genomics 5’) permitted simultaneous tracking of the T cell phenotype at the protein level, individual T cell clones, and gene expression dynamics between 4 timepoints: pre-treatment, and post-treatment weeks 1, 2, and 13. Here, we report the results of differential expression analyses between timepoints and patient-specific differences in T cell clonotype expansions. Both CD4+ and CD8+ T cells in our study patients had increased expression of T cell activation markers LTB, CISH, and CD74. CD8+ T cell subsets demonstrated additional elevations in genes important in cytotoxic function (granzymes (GZMA, GZMB) and perforin (PRF1)), MHC Class II expression (HLA-DRA, HLA-DRB1), and AP-1 transcription factor subunits (JUND, JUN, JUNB, FOS, FOSB). After excluding known viral antigen clonotypes, 2 of 4 patients demonstrated TCR clonotype expansion. Notably, nearly all the expanded TCR clonotypes were found within CD8+ T cells, but not CD4+ T cells. NT-I7 promotes activation, cytotoxic function, and selective clonotype expansion of CD8+ T cells in patients with HGG. This, combined with its role in increased CD4+ T cell counts, suggests NT-I7 may be a powerful tool to restore immune function after treatment-associated lymphopenia in HGG.

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 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.