Long-term Survivors Research Articles

Patient-reported persistent lymphedema and peripheral neuropathy among long-term breast cancer survivors in theCarolina Breast Cancer Study.

Improved breast cancer treatment has lengthened survival but also has long-term impacts. Lymphedema and peripheral neuropathy are treatment-related sequelae that extend into survivorship. Co-occurrence of these conditions may further impair functional well-being. Few studies have estimated the burden of these conditions among diverse survivors. Carolina Breast Cancer Study Phase 3 enrolled survivors diagnosed between 2008 and 2013 in North Carolina. Black and younger women (aged <50 years at diagnosis) were oversampled. With the use of ≥10 years of follow-up data, the prevalence of persistent lymphedema, peripheral neuropathy, and their co-occurrence was assessed. Prevalence differences (PDs) and 95% confidence intervals (CIs) were assessed according to patient and disease characteristics. A total of 1688 survivors were included, with an average of 11.1 years (SD, 0.6) postdiagnosis. The prevalence of persistent lymphedema, peripheral neuropathy, and their co-occurrence was 18.7%, 27.7%, and 8.8%, respectively. Lymphedema was higher among those receiving a mastectomy and with >5 lymph nodes removed, and peripheral neuropathy was higher among women treated with taxane-based chemotherapy. Co-occurrence was higher among women with >5 lymph nodes removed (vs. <5; PD, 5.4; 95% CI, 2.1 to 8.8) and those treated with taxane-based chemotherapy (vs. no chemotherapy; PD, 6.8; 95% CI, 3.9 to 9.7). The burden of lymphedema (PD, 2.7; 95% CI, 0.9 to 6.3) and peripheral neuropathy (PD, 5.8; 95% CI, 1.7 to 9.9) was higher among Black than White women. The prevalence of lymphedema (PD, 1.8; 95% CI, -1.5 to 5.1) and peripheral neuropathy (PD, 4.6; 95% CI, 0.8 to 8.4) was elevated among younger compared to older women. Lymphedema and peripheral neuropathy affect a substantial proportion of survivors. Interventions are needed to reduce this burden.

A defective cure rate quantile regression model for male breast cancer data

In this article, we particularly address the problem of assessing the impact of different prognostic factors, such as clinical stage and age, on the specific survival times of men with breast cancer when cure is a possibility. To this end, we developed a quantile regression model for survival data in the presence of long-term survivors based on the generalized Gompertz distribution in a defective version, which is conveniently reparametrized in terms of the q-th quantile and then linked to covariates via a logarithm link function. This proposal allows us to obtain how each variable affects the survival times in different quantiles. In addition, we are able to study the effects of covariates on the cure rate as well. We consider Markov Chain Monte Carlo methods to develop a Bayesian analysis in the proposed model and we evaluate its performance through Monte Carlo simulation studies. Finally, we illustrate the application of our model in a data set about male breast cancer from Brazil analyzed for the very first time.

Clinicopathological predictive factors in long-term survivors who underwent surgery for pancreatic ductal adenocarcinoma: A single-center propensity score matched analysis.

Long-term survivors (LTSs) after pancreatic resection of pancreatic ductal adenocarcinoma (PDAC) represent a particular subgroup of patients that remains poorly understood. The primary endpoint was to identify clinicopathological factors associated with LTSs after pancreatic resection for PDAC. This was a retrospective study of patients who had undergone pancreatic resection for PDAC. Long survival was defined as a patient who survived at least 60months. Patients were divided in two groups: LTS and short-term survivor (STS). The two groups were compared regarding epidemiological, clinical, and pathological data. Propensity score matching (PSM) was used to reduce selection bias with a 1:2 ratio. Multivariable analysis of significative predictive factors before and after PSM was done. Three hundred and thirty-three patients were enrolled: 46 (13.8%) in the LTS group and 287 (86.2%) in the STS group. Using PSM, 138 patients were analyzed: 46 in the LTS group and 92 in the STS group. At the multivariate analysis of significative predictive factor after PSM, adjuvant chemotherapy, well-differentiated tumors (G1), and R0 status were related to long-term survival (p=0.052, 0.010 and p=0.019, respectively). Kaplan-Meier survival curves confirmed these data. Additionally, Kaplan-Meier survival curves showed that pathological stage I was a favorable factor with respect to stage II, III, and IV. Long-term survival is possible after pancreatic cancer resection, even if in a small percentage. Significant predictors of long-term survival are administration of adjuvant chemotherapy, American Join Committee on Cancer stage I, well-differentiated tumor (G1), and R0 resection.

Abstract PR017: A T-cell signature in circulating cell-free DNA at time of diagnosis predicts response to checkpoint inhibition

Abstract Immune checkpoint inhibitors (ICI) are increasingly used as first line of treatment in a range of cancer types, owing to their efficacy and advantageous toxicological profile. Currently, PD-L1 expression and tumor mutation burden (TMB) are the most common biomarkers to select patients for ICI treatment, yet response to ICI remains highly variable between patients, necessitating more accurate early predictors of treatment response. Circulating cell-free DNA (cfDNA) originates from dying cells throughout the body, each molecule carrying unique epigenetic features of its cell-type of origin. Most studies on cfDNA focus on tumor-derived fragments for diagnostics or minimal residual disease detection. However, variations in the contribution of immune cells and other stromal cell populations could provide important clues to classify a tumor with respect to treatment. To address this, we collected tumor and adjacent normal tissue as well as cfDNA from the blood of 33 patients enrolled in the LUD2015-005 trial in which ICI were administered to patients with non-resectable esophageal adenocarcinoma (EAC) for four weeks, before adding standard-of-care chemotherapy (ICI+CTX). For each patient, we took samples at diagnosis, before ICI+CTX, during and at the end of treatment. Tissue and cfDNA samples were sequenced using TET-Assisted Pyridine-borane Sequencing (TAPS), a method recently developed in Oxford which provides genome-wide high-depth, base- resolution DNA methylation and mutation information from low-input samples. We then selected a representative set of high-purity tumor tissue samples and combined them with whole- genome TAPS data from 9 healthy blood cell types and 5 gastrointestinal tissues to generate a GI-specific atlas of cell-type specific methylation. This atlas allows us to accurately quantify the contribution of tumor and 14 healthy cell types to the cfDNA collected from each patient at each timepoint. Strikingly, the presence of T-cell derived cfDNA at time of diagnosis (tDNA) is a strong positive predictive marker of overall survival (p=0.0024). In contrast, the fraction of tumor-resident T-cells, estimated by either bulk tissue TAPS or RNA sequencing, correlated only weakly with treatment response in this cohort, indicating that T-cell activity is more accurately captured by tDNA. Furthermore, we find that patients with a combination of high TMB and high tDNA have an 80% 2-year survival probability, as opposed to below 25% for others, suggesting that tDNA is derived from T-cells actively engaging tumor cells with high neoantigen load. In summary, we demonstrate that T-cell turnover, as reflected in differential methylation in a set of marker regions spanning only 24kb, is a promising biomarker of treatment response, especially when combined with neoantigen load: in the presented cohort, all but one long-term survivors (alive at last follow up &amp;gt; 3 years after diagnosis) were tDNA positive with high TMB. This demonstrates the power of cfDNA composition analysis for risk stratification in ICI treatment. Citation Format: Phil Xie, Zohar Etzioni, Chun-Xiao Song, Richard P Owen, Mark R Middleton, Xin Lu, Benjamin Schuster-Boeckler. A T-cell signature in circulating cell-free DNA at time of diagnosis predicts response to checkpoint inhibition [abstract]. In: Proceedings of the AACR Special Conference: Liquid Biopsy: From Discovery to Clinical Implementation; 2024 Nov 13-16; San Diego, CA. Philadelphia (PA): AACR; Clin Cancer Res 2024;30(21_Suppl):Abstract nr PR017.

Abstract 4147601: Associations between Accelerated Aging Phenotypes with Cancer-Specific and Cardiovascular-Specific Mortality in Long-Term Cancer Survivorship

Background: The consequences of cancer and anti-cancer treatments are often described as representing an “accelerated aging” phenotype. However, little is known about how the “accelerated aging” phenotype affects mortality risks in long-term cancer survivors. Purpose: To investigate the association between accelerated aging phenotype and cause-specific mortality in a sample of long-term cancer survivors Methods: Data for cancer survivors (CS) were extracted from the National Health and Nutrition Examination Survey between the years 1999-2010. Participants missing vital data and those diagnosed with multiple cancers, childhood cancers, cancer within the previous 5 years, or skin cancer were excluded. Mortality outcomes were collected from the National Death Index through December 2019. The Phenotype Age score was derived from blood biochemistry measures such as albumin, creatinine, and c-reactive protein. Accelerated Aging (AA) was defined as a Phenotype Age greater than the participants’ chronological age. CS were grouped by time since diagnosis: 5-10, 10-15, 15-20, and ≥20 years. Within each group, hazard ratios (HR) were derived from competing-risk hazard regression for the AA phenotype association with cancer-specific and cardiovascular-specific mortality. Regressions were modeled with participant age as the time-scale to account for the predictive nature of chronological age. Results: A total of 875 CS (65.6±12.9 years, 62% female, 31% non-white, 15.6±9.4 years from cancer diagnosis) were included. The most common cancer types were prostate (16%) and breast (21%) cancer. There were 107 cancer and 113 cardiovascular deaths over a 10.8±4.6 year follow-up. The AA phenotype was significantly associated with cardiovascular-specific mortality in each survivor group (all p&lt;0.05). Conversely, the AA phenotype was only significantly associated with cancer-specific mortality in the 5-10 years of survivorship group (p=0.01). Results are displayed in Figure 1, along with cubic splines fit to the HR of each survivorship group. Conclusions: Present results suggest that the AA phenotype may demonstrate time-dependent associations with cancer-specific and cardiovascular-specific risks, two leading causes of death in CS.

Abstract 4136040: Wearable Device-Measured Physical Activity and Incident Cardiovascular Diseases In Cancer Survivors

Background: Cardiovascular diseases (CVD) is the leading cause of non-cancer mortality among cancer survivors. Despite the known benefits of physical activity on cardiovascular health in the general population, evidence regarding post-diagnosis physical activity and CVD risk among cancer survivors is limited. Objectives: To explore the associations of wearable device-measured moderate-to-vigorous intensity physical activity (MVPA) with CVD risk in long-term cancer survivors. Methods: The retrospective analysis involved a prospective cohort of 6109 cancer survivors without CVD from the UK Biobank accelerometry subsample. Cancer diagnoses were obtained from national cancer registries (International Classification of Diseases-10 [ICD-10], C00-C97, except for non-melanoma skin cancer, in situ, and non-well-defined cancers), and participants were followed up through December 31, 2022. A machine-learning algorithm was utilized to categorize MVPA into four groups based on guideline-recommend MVPA duration (0-75 min/week, 75-150 min/week, 150-300 min/week, ≥300 min/week). Results: Over a median follow-up of 7.88 years, there were 539 incident CVD events, including 361 incident CAD events, 155 incident HF events, and 109 incident stroke events. A clear inverse linear dose-response relationship between MVPA volume and the incidence of CVD was observed (P for nonlinear=0.49), with no maximal threshold for the benefits. Adjusted CVD incidence rates (95% confidence intervals [CIs]) across MVPA groups (0-75 min/week, 75-150 min/week, 150-300 min/week, ≥300 min/week) were 15.30 (12.90, 18.10), 13.50 (11.00, 16.40), 12.00 (10.20, 14.10), and 9.86 (8.35, 11.60) per 1000 person-years, respectively. Adjusted hazard ratios (95% CI) for CVD, CAD, HF, and stroke in the highest MVPA group (≥300 min/week) compared with those with the lowest MVPA group (0-75 min/week) were 0.63 (0.49, 0.80), 0.68 (0.51, 0.91), 0.66 (0.42,1.06), 0.72 (0.42, 1.23), respectively. Conclusions: Findings from the UK Biobank study suggest that longer durations of MVPA are associated with reduced incident CVD risk in cancer survivors, particularly in CAD risk reduction, underscoring the potential for physical activity to serve as a key component in cardio-oncology care.

Abstract 4136755: Associations of Pulmonary Hypertension and Lung Cancer: A Prospective Cohort Study of Half a Million UK Biobank Participants

Background: Pulmonary hypertension (PH) and lung cancer (LC) are both significant public health issues with substantial morbidity and mortality. Recent studies suggest potential associations between pulmonary vascular diseases and LC due to shared risk factors and pathophysiological mechanisms, yet comprehensive research in large populations is scarce. Methods: This prospective cohort study utilized data from the UK Biobank, with baseline assessment between 2006 and 2010 and follow-up until November 30, 2023, for England and Scotland, and May 31, 2022, for Wales. We included 6,425 participants with LC, identified using linked cancer registry data, and followed them for the incidence of PH over a period of 10 years. We adjusted for potential confounders including age, ethnics, sex, smoking status, BMI, and histologic subtypes of LC. Statistical analyses were performed using Time-dependent Cox proportional hazards models to estimate the associations between PH and LC. Results: Of 502,173 participants in this prospective cohort, 6,425 were diagnosed with LC, while 494,451 did not receive the LC diagnosis. The prevalence of PH in the LC cohort and the no-LC cohort were 0.64% (1,494 of 3,142 women [47.55%]) and 2.40% (59 of 154 women [38.31%]), respectively, with significant difference between the two groups (p&lt;0.001). In the LC cohort, the mortality rates of patients without PH and with PH were 69.18% and 77.92% (p=0.020). Among the patients diagnosed with LC and PH, 33.12% were diagnosed with LC after PH (PH-LC), while 66.88% were diagnosed with LC before PH (LC-PH). And the mortality rates of the PH-LC group and the LC-PH group were 78.43% and 77.67%, respectively, with no significant difference between the two groups (p=0.915). Time-dependent Cox regression analysis showed that PH shows an increasing trend in risk (5th year HR: 3.22, 95% CI: 2.09-4.99, p-value &lt; 0.001), highlighting its significant impact on LC long-term prognosis. Conclusion: To conclude, the presence of PH significantly increased the risk of mortality in participants with LC, especially for the long-term LC survivors. And certain percentage of patients were diagnosed with LC before PH, but they had no significant difference between the patients with LC after PH.

Abstract 4118444: Right Ventricular Contractile Reserve and Right Ventricular-Pulmonary Arterial Coupling Are Impaired in Long-Term Survivors of Childhood Cancers

Background: Childhood cancer survivors are at risk of right ventricular (RV) dysfunction in relation to cardiac toxicity due to chemotherapy and radiation therapy. This study tested the hypothesis that RV contractile reserve and RV-pulmonary arterial (PA) coupling are altered in long-term survivors of childhood cancers. Methods: Thirty survivors (60% men) aged 24.3 ± 5.2 years at 15.3 ± 6.3 years after completion of chemotherapy and thirty healthy control subjects (47% men) were studied. Resting and submaximal supine bicycle stress echocardiography was performed for assessment of RV fractional area change (FAC), tricuspid annular plane systolic excursion (TAPSE), left ventricular (LV) and RV longitudinal strain, mitral and tricuspid annular velocities and myocardial acceleration during isovolumic contraction (IVA). The slope of the RV force-frequency relationship was derived from the change in IVA with the change in heart rate during exercise (△IVA/△heart rate), while RV-PA coupling was determined by the ratio between TAPSE and pulmonary arterial acceleration time indexed to RV ejection time (PAATi). Results: At rest, tricuspid annular systolic velocity and RV systolic strain were significantly lower in survivors ( P &lt; 0.05 for both), while RV FAC, TAPSE and IVA were similar between the two groups ( P &gt; 0.05 for all). During submaximal exercise testing, all RV systolic functional indices were significantly lower in survivors than controls ( P &lt; 0.05 for all). The slope of the RV force-frequency relationship was significantly flatter in survivors compared to controls (0.038 ± 0.002 vs 0.059 ± 0.003 m/sec 2 beats/min, P &lt; 0.001). For RV-PA coupling, TAPSE/PAATi was similar between survivors and controls at baseline but became significantly lower in survivors during submaximal exercise ( P = 0.002). Conclusions: The RV contractile reserve and RV-PA coupling are impaired during exercise in long-term survivors of childhood cancers. Future studies aimed at determining the clinical and prognostic significance of these impairments are warranted.

PATH-66. MOLECULAR FEATURES RELATED TO LONG-TERM SURVIVAL IN GLIOBLASTOMA

Abstract Glioblastoma Multiforme (GBM) remains the most common malignant primary brain tumor in adults, with a dismal prognosis that rarely exceeds beyond 2 years of survival despite multimodal treatment. While small fractions of GBM patients seem to display extended survival, the underlying mechanisms for this peculiarity remain largely unknown. Previously published investigations of long-term survivors (LTS) usually incorporate small numbers of patients, non-uniform definition of LTS and rarely provide a comprehensive molecular analysis. With advances in multi-omics technologies and their integration with disease diagnostics, numerous prognostic molecular markers have been proposed. So far, only O6-methylguanine-DNA-methyltransferase (MGMT) gene promotor hypermethylation was linked to outcome and therapy response. We aim to investigate omics characteristics associated with LTS. Molecularly confirmed Isocitrate Dehydrogenase (IDH) wildtype GBM patients, &amp;gt;18 years old, operated and treated at our institution between 2013 and 2020 and living ≥5 years post-diagnosis (LTS = 62) or 1-2 years (STS = 62) were identified. Clinical and demographic characteristics were matched. Tumor tissues was analyzed with targeted next generation sequencing (NGS) and compared between LTS and STS. In addition, methylation analysis was done for all LTS. Results will be presented. We hope to shed a broader light on the molecular drivers behind the LTS in GBM patients, that will provide prognostic markers and potential targets for novel treatments.

CTNI-65. DETERMINANTS OF LONG-TERM SURVIVAL IN PATIENTS WITH IDH-MUTANT GLIOMAS

Abstract BACKGROUND Survival times of patients with IDH-mutant gliomas is variable and can extend to decades. Many studies only provide progression-free rather than overall survival times and prognostic factors remain ill-defined. Here we explored clinical disease characteristics of long-term survivors within a large cohort of patients with extended follow-up. METHODS This single-center, retrospective analysis included 114 patients with IDH-mutant glioma that either died due to tumor-related causes or survived at least 15 years after first diagnosis. Patient characteristics, outcomes, and prognostic factors were stratified by short- (&amp;lt; 15 years) versus long-term (≥ 15 years) survival. Initial diagnosis was (re-)classified according to the WHO 2016 classification. Uni- and multivariate analyses were performed. RESULTS Overall, 66 patients (58%) were diagnosed with astrocytoma and 48 patients (42%) with oligodendroglioma. Median follow-up of the survivors was 16.6 years (range 15-28.9). 62 tumor-related deaths (54%) had been reported at database closure. Patients that died before reaching 15 years survival time had been diagnosed with astrocytoma in 41 (72%) and oligodendroglioma in 16 cases (28%). The long-term survivor cohort comprised 25 patients (44%) with astrocytoma and 32 patients (56%) with oligodendroglioma. Long-term survival was associated with grade 2 histology (p &amp;lt; 0.01), smaller tumor volumes (p &amp;lt; 0.01), and lack of contrast enhancement (p = 0.02). 41 long-term survivors (72%) were initially monitored by a wait-and-scan strategy as opposed to 16 patients (28%) in the cohort of short-term survival (p&amp;lt;0.01). In patients with oligodendroglioma, a higher KPS was associated with longer survival (HR 0.25; 95% CI 0.02-0.67; p = 0.05). Tumor resection (HR 0.43; 95% CI 0.22-0.86; p = 0.02) and wait-and-scan strategies (HR 0.34; 95% CI 0.14-0.79; p = 0.01) were associated with longer survival in patients with astrocytoma. CONCLUSION Tumor resection followed by a wait-and-scan strategy may yield excellent survival times, especially in patients with IDH-mutant grade 2 astrocytoma. Age appears not be an important predictor for survival in patients with IDH-mutant gliomas.

BIOM-63. LONG-TERM SURVIVAL AND MOLECULAR CHARACTERIZATION OF IDH-WILDTYPE GLIOBLASTOMA IN AN ASIAN COHORT

Abstract BACKGROUND Glioblastoma (GB), the most aggressive form of brain tumor, presents a significant clinical challenge with a devastating prognosis. Globally, the median overall survival (OS) for GB is typically 12-15 months, largely due to its inherent resistance to chemotherapy and radiotherapy. However, some patients exhibit prolonged survival, and their specific demographic and genomic characteristics remain poorly defined. Understanding the clinical profile of these exceptional responders holds great promise for informing improved management strategies for GB. METHODS In a retrospective two-center study conducted in Hong Kong (IRB: UW 21-189), we recruited 80 patients diagnosed with IDH wildtype glioblastoma. All patients underwent next-generation sequencing as part of their treatment. Long-term survivor (LTS) was defined as &amp;gt;=36 months from diagnosis, while medium-term survivor (MTS) was defined as &amp;gt;=18 months, and &amp;lt;18 months as short-term survivors (STS). When appropriate, descriptive statistics were used to report frequency with percentage or median with range. Fisher’s exact test was employed to analyze categorical variables, while continuous variables were assessed using the Kruskal-Wallis test. All statistical analyses were conducted using R (version 4.2.3). Result: Among the cohort of 80 recruited patients, the median survival was 18.8 months (95% CI 17.2-24.8). Notably, 21% (n=17) were LTS, 31% (n=25) were MTS, and 48% (n=38) were STS. A statistically significant variation (p &amp;lt; 0.05) was evident across three groups: gender distribution, the number of resections performed, the proportion of patients receiving genomic-guided treatment, and their participation in clinical trials. However, no significant difference was observed in MGMT promoter status and ECOG score. CONCLUSION Identifying these clinical factors enhances the clinical management of GB. The implications of these findings underscore the potential importance of incorporating genomic-guided treatment in both local and global clinical practices in GB.

RADT-38. CLINICAL, MOLECULAR AND IMAGING FEATURES ASSOCIATED WITH LONG TERM SURVIVAL IN GLIOBLASTOMA PATIENTS

Abstract INTRODUCTION Glioblastoma (GBM) is the most common malignant brain tumor in adults and has poor prognosis despite standard of care treatment. Nevertheless, certain patients surpass survival expectations. This study seeks to identify the clinical, molecular, and imaging characteristics of GBM associated with extended patient survival. METHODS In this retrospective cohort study, we examined records of adult GBM patients (WHO 2016 classification) treated at Thomas Jefferson University Hospital from 2010 to 2023. Exclusion criteria included a preoperative Karnofsky Performance Status (KPS) below 60 and treatment with hypo-fractionated radiation therapy. Patients were categorized into two groups: short-term survivors (STS), who survived less than 36 months from diagnosis, and long-term survivors (LTS), who survived more than 36 months. We reviewed patient charts and pathology reports for comprehensive clinical and molecular data. For radiomics analysis, tumor segmentation was performed using CaPTk software on the initial diagnostic MRI (T1 pre and post-contrast, FLAIR and T2 sequences). The relationship between overall survival of more than three years was analyzed with univariable logistic models for potential predictors using R statistical software. RESULTS Of the cohort of 210 patients, 37 (17.6%) survived beyond three years. The median age at diagnosis was 55 years (range; 29-79) Twenty-two patients were male and 15 were female. Twenty-two percent had IDH mutation and 65% had MGMT methylation. Factors associated with long-term survival included younger age at diagnosis (p =0.007), MGMT hypermethylation (p =0.019), IDH mutation (p=0.001), absence of TERT mutation (p = 0.002), higher average number of adjuvant temozolomide cycles (10 vs. 5; p = 0.005), and smaller volume of enhancing tumor on T1 post-contrast imaging segmentation (p=0.022). But there was no significant difference in FLAIR abnormality or necrotic core volumes between the groups. CONCLUSION In our cohort of GBM patients, patients diagnosed at a younger age, MGMT hypermethylation, IDH mutation, absence of TERT mutation, receiving more cycles of adjuvant temozolomide treatment, and smaller enhancing tumor volume on preoperative T1 post-contrast imaging were associated with longer survival. Future research involving larger cohorts and validation of our findings is needed.

EXTH-69. DEVELOPMENT OF A NOVEL, HUMAN ANTIBODY TO IMPROVE ONCOLYTIC VIRUS THERAPY FOR GLIOBLASTOMA

Abstract Glioblastoma (GBM) is the most aggressive, malignant, primary brain tumor with abysmal overall survival. GBM is regarded as an “immune cold” tumor due to poor immune cell infiltration and immunosuppressive signaling in the tumor microenvironment (TME). Oncolytic herpes virus (oHSV) therapy has emerged as a possible therapeutic avenue for solid tumors such as GBM. We have observed that oHSV-treated tumor cells release extracellular ATP (eATP) which functions as immunostimulatory signaling molecule. In the TME, eATP is rapidly hydrolyzed into immunosuppressive adenosine by ectoenzymes CD39 and CD73. Using global CD73 knock out (CD73KO) mice or a function-blocking murine antibody, we found that blocking CD73 activity improves oHSV therapy in vivo. Intracranial tumor-bearing CD73KO mice respond significantly better to oHSV therapy than wild type (WT). These long-term survivors also rejected a subsequent tumor challenge, demonstrating development of a memory response. scRNA-seq revealed significantly increased immune cell infiltration in CD73KO mice compared to WT. We evaluated cellular crosstalk using CellChat and uncovered a major CCL-directed signaling pathway in the CD73KO mice. Furthermore, we identified a novel, human CD73 antibody from panning an scFv phage display library derived from human tonsils. This antibody, Ab6, demonstrated functional inhibition of purified CD73 and very high binding affinity for CD73. Co-culture of human GBM cells treated with OV and Ab6 and donor PBMCs resulted in increased tumor cell death. Additionally, human DCs exposed to Ab6 and OV-treated conditioned media were better able to activate T cells. To evaluate in vivo efficacy of this novel antibody, we have generated custom humanized CD73 knock-in mice wherein human CD73 has replaced murine CD73. We are currently evaluating the efficacy of Ab6 and oHSV in these mice against intracranial glioma. These results will support the translation of Ab6 as a potential immune therapeutic to add to the arsenal against brain tumors.

CSIG-25. MAPK/ERK SIGNALING IN GLIOMAS MODULATES INTERFERON RESPONSES, PROMOTES TUMOR-MICROGLIA CROSSTALK, AND CONFERS SUSCEPTIBILITY TO ANTI-PD-1 AND ANTI-CTLA-4 IMMUNOTHERAPY

Abstract While immune checkpoint blockade (ICB) is not effective in unselected glioblastoma (GBM) patients, we previously established that MAPK/ERK signaling is associated with overall survival following anti-PD-1 and anti-CTLA-4 treatment in recurrent GBM. However, the causal relationship between MAPK/ERK signaling and susceptibility to ICB, as well as the mechanisms underlying this association, remain to be determined. We conducted in vivo kinome-wide CRISPR/Cas9 screenings in murine gliomas to identify key regulators of susceptibility to anti-PD-1 and CD8+ T-cell response and performed survival studies to validate the most relevant hits. Additionally, paired scRNA-seq with p-ERK staining, spatial transcriptomics, and ex-vivo slice culture of BRAFV600E mutant GBM tumors treated with BRAFi/MEKi were used to determine the causal relationship between MAPK signaling, tumor cell immunogenicity, and modulation of microglia phenotype. Our CRISPR/Cas9 screening results identified the MAPK pathway, particularly the RAF-MEK-ERK pathway, as the most critical modulator of glioma susceptibility to anti-tumoral immunity across all kinases. Survival studies showed that mice bearing high p-ERK gliomas exhibited prolonged survival with anti-PD-1 treatment, which was not seen when ERK phosphorylation diminished. MAPK activation in murine gliomas led to durable anti-tumoral immunity upon implant re-challenge, with memory T cell infiltration in long-term survivors. Elevated p-ERK in glioma cells was associated with interferon responses and antigen presentation. Moreover, in BRAFV600E human GBM cells with ERK1/2 knockout and in slice cultures of human BRAFV600E GBM tissue analyzed by spatial transcriptomics, we observed modulation of interferon responses by the MAPK/ERK pathway. Notably, in slice cultures from BRAFV600E mutant GBM, BRAFi/MEKi treatment disrupted the interaction between tumor cells and tumor-associated macrophages/microglia. In conclusion, the MAPK/ERK pathway is a critical driver of GBM susceptibility to anti-tumoral immunity, modulating the interferon responses and antigen-presenting machinery in glioma cells, as well as tumor cell interaction with the microenvironment.

TMIC-54. OHSV-MEDIATED NOTCH BLOCKADE FOR BRAIN TUMORS

Abstract Primary brain tumors such as glioblastoma (GBM) are refractory to current standard-of-care, and so there is an urgent need to develop novel therapies to treat brain tumors. NOTCH is a cell-cell communication pathway that is exploited by GBM stem cells to bypass treatment. The role of NOTCH signaling in tumor growth and resistance is well studied, but the significance of this pathway for immunotherapy of GBM is not very well understood. We have recently shown that NOTCH activation with viro-immunotherapy contributes to tumor regrowth and induces recruitment of monocytic MDSC cells into the tumor, which limit optimal immune activation to kill tumor cells. Herein, we evaluated the impact of blocking NOTCH signaling using two different peptides: NIX1 and NIX2 that can interfere with NOTCH ligand binding with their receptors. Both NIX1 and NIX2 could effectively block the ligation of NOTCH ligands with Notch receptors in the tumor microenvironment. Secretion of both NIX1 and NIX2 was confirmed by western blot (WB) and ELISA. Functionality of NIX1 and NIX2 to block NOTCH signaling was assessed by western blot analysis for NOTCH cleaved intracellular domain (NICD). RNA sequencing and PCR based assays were utilized to evaluate the impact of NIX1 and NIX2 on global pathways that were enriched. Gene therapy using oncolytic immunotherapy vectors revealed that both NIX1 and NIX2 could suppress NOTCH signaling. In vitro, NIX1 and NIX2 did not increase the benefit of viro-immunotherapy. Treatment of mice bearing intracranial tumors with NIX1 or NIX2 armed viro-immunotherapy revealed a significant increase in therapeutic benefit with some long-term survivors. Both NIX1 and NIX2-expressing viruses induced macrophage migration relative to unarmed viro-immunotherapy in two different glioma models. Role of macrophages in guiding therapeutic benefit is currently being explored.

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&amp;lt;0.001; median: 1559 vs. 1959) and in FLAIR hyperintense regions (t-value: 3.585, p&amp;lt;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&amp;lt;0.001; median: 0.71 vs. 0.72) and in non-enhancing regions (t-value: 2.606, p&amp;lt;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.

CTIM-34. EFFECTS OF NEOADJUVANT IMMUNE CHECKPOINT INHIBITION ON PEDIATRIC AND ADULT HIGH-GRADE GLIOMAS

Abstract High-grade gliomas (HGG) are lethal tumors with few long-term survivors affecting adult and pediatric patients. Studies investigating immune checkpoint inhibition (ICI) suggest administration of neoadjuvant anti-PD1 blockade (neo-aPD1) enhances local and systemic anti-tumor responses. This data is supported by increased T cell density in the tumor and proportion of cytotoxic T cells in peripheral blood. In a previous randomized clinical trial, neo-aPD1 improved survival in adult with recurrent glioblastoma. In this study, we utilized multiplex immunofluorescence (mIF), and single-cell RNA sequencing (scRNA-seq) to investigate the effects of neoadjuvant ICI on the TME and compare between pediatric and adult populations. Tissue samples from adult patients with recurrent GBM treated with neo-aPD1 (n=22) or adjuvant only therapy (n=5) were obtained from our UCLA off-label neo-PD1 study. Tissue samples were also obtained from pediatric patients with recurrent/progressive HGG treated with neoadjuvant ICI from the ongoing Pediatric Neuro-Oncology Consortium study PNOC19. Samples included diagnostic tissue from two patients and on study surgery tissue from four patients. All tissue samples were subjected to mIF and underwent imaging analysis to assess immune cell infiltration by quantifying lymphoid and myeloid cell densities across the two treatment groups. Our preliminary findings elucidated a trend of higher T cell infiltration in adult neoadjuvant compared to adjuvant-only treated patients (median density 58.11 vs 15.15 T-cells/mm2). Compared to their adult counterparts, neoadjuvant ICI treated pediatric patients had even more robust total T cell infiltration (median density 268.10 vs 58.11 T-cell/mm2, pediatric vs adult respectively). scRNA-seq analysis revealed a greater enrichment of monocytic macrophages in the pediatric population compared to tissue resident microglia in the adults. This early data requires analysis of additional samples to better understand differences in the anti-tumor immune response between adult and pediatric recurrent/progressive HGG patients.

SURG-49. INVESTIGATING LITT-BASED COMBINATION THERAPIES IN PRECLINICAL GLIOMA MODELS

Abstract BACKGROUND Laser interstitial thermal therapy (LITT) is a minimally invasive means of tumor cyto-destruction with the potential for additional clinical benefits, such as altering the blood-brain barrier or the brain tumor microenvironment (TME). Using a murine model of GBM, we utilized a clinically relevant laser ablation model to identify and exploit immune TME changes after LITT to generate therapies that improve mouse survival, with the potential for rapid clinical translation. METHODS Right frontal lobe implantation of the immune “cold” SB28 murine glioma cells were performed in C57BL/6J mice. Tumor location was verified by MRI followed by stereotactic insertion of a paired fiberoptic laser and thermocouple to perform real-time hyperthermic ablation with temperature monitoring. Pulsed laser application maintained a peri-lesional temperature of 44°C for 150-180 seconds. Following LITT (or sham surgery), spectral flow cytometry was used to profile the immune TME. Survival studies were performed using a combination of LITT and immune modulating therapies. RESULTS Laser ablation alone provided a survival benefit compared to sham surgery (median survival: 29 vs 22.5 days, P&amp;lt;0.0001) in in glioma-bearing mice. Survival studies combining LITT with anti-PD1 lacked a significant response in the SB28 model but showed some long-term survivors. Flow cytometry performed on brain tissue post-LITT days 3 and 7 demonstrated little to no change in CD4+/CD8+ T cell responses but did show an increase in neutrophils, which expressed TLR2 and 4. The TME showed negligible numbers of phagocytic cells with obvious tumor cell uptake post-LITT. Using these results, we generated strategies for LITT-based combination immune therapies. Survival studies are ongoing using combinations of LITT/anti-PD1 with neutrophil depletion, inhibition of anti-CD47, and addition of broad TLR2/4 agonists as a neutrophil stimulus. CONCLUSIONS A clinically relevant immunocompetent murine LITT model enables the generation of novel treatment strategies with potential for rapid clinical translation.

NCOG-30. FACTORS ASSOCIATED WITH COGNITIVE IMPAIRMENT IN LONG-TERM IDH-MUTANT GLIOMA SURVIVORS

Abstract BACKGROUND Cognitive deficits are less frequent in patients with IDH mutant (IDHm) than wild-type glioma at time of diagnosis, but less is known about factors that influence cognition for long-term survivors. We evaluated long-term neuropsychological outcomes of patients with IDHm glioma. METHODS Patients with IDHm glioma who underwent clinical neuropsychological assessment at Massachusetts General Hospital 3+ years after diagnosis were included and compared to a previously published cohort of IDHm patients tested prior to surgery/diagnosis (Wefel et al., 2016). RESULTS Sixty-three patients were included for analysis (54% male; median age 45 [range 21-75], 16 years of education, and 7 years from diagnosis [range 3-28]). Thirty-eight patients (60%) had astrocytoma and 24 (40%) had oligodendroglioma; 28 (44%) were grade 2, 31 (49%) grade 3, and 4 (6%) grade 4. Fifty-five patients (87%) received radiation and 51 (81%) received chemotherapy. Cognitive impairment (defined as Z score ≤-1.5 on at least two tests) was present in 30 patients (48%) and was associated with lower scores in neurologic aspects of quality of life (QoL; p&amp;lt;0.01), grade 3/4 relative to grade 2 (p=0.01), older age (p=0.03), left-sided lateralization (p=0.02), and less education (p=0.01). Prior radiation (p=0.07) and photon relative to proton radiation (p=0.06) trended toward poorer function. Tumor type, disease duration, and extent of resection were not significant factors (p&amp;gt;0.05). Compared to the pre-diagnosis IDHm cohort, impairment was significantly more common on tests of processing speed and language. Learning/memory, executive, and visuospatial function trended toward more frequent impairment but were not significant. Attention had comparable frequency of impairment. CONCLUSIONS In this cohort of IDHm glioma survivors, neurocognitive deficits were common, related to QoL, and associated with some expected clinical factors, but not length of survival. These findings emphasize the need for future research on interventions aimed at supporting patients’ neurocognitive abilities and QoL.

IMMU-38. LEVERAGING INNATE IMMUNE SENSORS TO GENERATE DURABLE ANTI-GLIOMA ADAPTIVE IMMUNE RESPONSES

Abstract Glioblastoma harbors a tumor microenvironment (TME) that is mostly devoid of T cell effector infiltration but is dominated by immune suppressive microglia, macrophages, and myeloid-derived suppresser cells. The innate immune cells in the TME have impaired phagocytosis and antigen presentation and are inadequate for triggering the subsequent immune activating signals needed for anti-tumor effector responses. Phagocytic activity can also be blocked by the upregulation of CD47 on the tumor cells. In the immune checkpoint resistant Qki-/- Pten-/- P53-/- (QPP) glioma model, intratumoral treatment with the synthetic cyclic di-nucleotide STING agonist IACS-8803 (8803) induces global immunological reprogramming and long-term survival resistant to tumor rechallenge. More specifically, in the infiltrating myeloid stroma 8803 increases costimulatory protein CD86 while reducing the expression of suppressive markers CD163 and CD206. Conventional type 1 dendritic cells are increased in both the TME (p&amp;lt;0.05) and the draining cervical lymph node (p&amp;lt;0.01). Intratumoral infiltration of both CD8 T (p&amp;lt;0.05) and NK (p&amp;lt;0.001) cells increases. However, only T cells, but not NK cells, are necessary for 8803 therapeutic activity when assessed with in vivo NK cell depletion studies and treatment in the RAG-/- background. STING activation increases microglial phagocytic capacity, but also induces a compensatory increase in SIRPα expression (p&amp;lt;0.001) – the ligand for CD47. 8803 synergizes with anti-CD47 blockade to enhance microglia phagocytosis of QPP glioblastoma cells in vitro. Finally, the combination of 8803 and anti-CD47 synergizes to extend both median survival and the fraction of long-term survivors in orthotopic QPP-bearing mice (QPP8v; vehicle control MS=39d, anti-CD47 MS=40d, 8803 MS=67d 20% long-term survival, 8803 + anti-CD47 MS=107.5d 40% long-term survival). These data demonstrate that 8803 induces proinflammatory conversion of the glioblastoma TME, generates T cell-dependent survival benefits in QPP-bearing mice, and synergizes with anti-CD47 blockade to enhance microglia phagocytosis of glioblastoma cells and extend survival in QPP-bearing mice.