Search

The central nervous system (CNS) antigen-presenting cell (APC) that primes antitumor CD8+ T-cell responses remains undefined. Elsewhere in the body, the conventional dendritic cell 1 (cDC1) performs this role. However, steady-state brain parenchyma cDC1 are extremely rare; cDCs localize to the choroid plexus and dura. Thus, whether the cDC1 play a function in presenting antigen derived from parenchymal sources in the tumor setting remains unknown. Using preclinical glioblastoma (GBM) models and cDC1-deficient mice, we explored the presently unknown role of cDC1 in CNS antitumor immunity. We determined that, in addition to infiltrating the brain tumor parenchyma itself, cDC1 prime neoantigen-specific CD8+ T cells against brain tumors and mediate checkpoint blockade-induced survival benefit. We observed that cDC, including cDC1, isolated from the tumor, the dura, and the CNS-draining cervical lymph nodes harbored a traceable fluorescent tumor antigen. In patient samples, we observed several APC subsets (including the CD141+ cDC1 equivalent) infiltrating glioblastomas, meningiomas, and dura. In these same APC subsets, we identified a tumor-specific fluorescent metabolite of 5-aminolevulinic acid, which fluorescently labeled tumor cells during fluorescence-guided GBM resection. Together, these data elucidate the specialized behavior of cDC1 and suggest that cDC1 play a significant role in CNS antitumor immunity.

Supplementary Figures and Tables.

The central nervous system (CNS) antigen-presenting cell (APC) that primes antitumor CD8+ T-cell responses remains undefined. Elsewhere in the body, the conventional dendritic cell 1 (cDC1) performs this role. However, steady-state brain parenchyma cDC1 are extremely rare; cDCs localize to the choroid plexus and dura. Thus, whether the cDC1 play a function in presenting antigen derived from parenchymal sources in the tumor setting remains unknown. Using preclinical glioblastoma (GBM) models and cDC1-deficient mice, we explored the presently unknown role of cDC1 in CNS antitumor immunity. We determined that, in addition to infiltrating the brain tumor parenchyma itself, cDC1 prime neoantigen-specific CD8+ T cells against brain tumors and mediate checkpoint blockade-induced survival benefit. We observed that cDC, including cDC1, isolated from the tumor, the dura, and the CNS-draining cervical lymph nodes harbored a traceable fluorescent tumor antigen. In patient samples, we observed several APC subsets (including the CD141+ cDC1 equivalent) infiltrating glioblastomas, meningiomas, and dura. In these same APC subsets, we identified a tumor-specific fluorescent metabolite of 5-aminolevulinic acid, which fluorescently labeled tumor cells during fluorescence-guided GBM resection. Together, these data elucidate the specialized behavior of cDC1 and suggest that cDC1 play a significant role in CNS antitumor immunity.

Clonal clustering assignments generated from sciClone.

SMA-560 Composite

Supplementary Figure S1. Mutation Spectra of each subclonal population. Supplementary Figure S2. Somatic Copy Number calls. Top: Primary, Middle: C7-T2 Metastasis, Bottom: T7-8 Metastasis. Supplementary Figure S3. Mutation signatures derived for each subclone independently. Supplementary Figure S4: Expression of immune-related genes.

Supplementary Figure from Characterization of the Genomic and Immunologic Diversity of Malignant Brain Tumors through Multisector Analysis

GL261 Composite

Supplementary Table from Characterization of the Genomic and Immunologic Diversity of Malignant Brain Tumors through Multisector Analysis

The “cancer immunogenomics” paradigm has facilitated the search for tumor-specific antigens over the last 4 years by applying comprehensive cancer genomics to tumor antigen discovery. We applied this methodology to identify tumor-specific “neoantigens” in the C57BL/6-derived GL261 and VM/Dk-derived SMA-560 tumor models. Following DNA whole-exome and RNA sequencing, high-affinity candidate neoepitopes were predicted and screened for immunogenicity by ELISPOT and tetramer analyses. GL261 and SMA-560 harbored 4,932 and 2,171 nonsynonymous exome mutations, respectively, of which less than half were expressed. To establish the immunogenicities of H-2Kb and H-2Db candidate neoantigens, we assessed the ability of the epitopes predicted in silico to be the highest affinity binders to activate tumor-infiltrating T cells harvested from GL261 and SMA-560 tumors. Using IFNγ ELISPOT, we confirmed H-2Db–restricted Imp3D81N (GL261) and Odc1Q129L (SMA-560) along with H-2Kb–restricted E2f8K272R (SMA-560) as endogenous tumor-specific neoantigens that are functionally immunogenic. Furthermore, neoantigen-specific T cells to Imp3D81N and Odc1Q129L were detected within intracranial tumors as well as cervical draining lymph nodes by tetramer analysis. By establishing the immunogenicities of predicted high-affinity neoepitopes in these models, we extend the immunogenomics-based neoantigen discovery pipeline to glioblastoma models and provide a tractable system to further study the mechanism of action of T cell–activating immunotherapeutic approaches in preclinical models of glioblastoma. Cancer Immunol Res; 4(12); 1007–15. ©2016 AACR.

Despite some success in secondary brain metastases, targeted or immune-based therapies have shown limited efficacy against primary brain malignancies such as glioblastoma (GBM). Although the intratumoral heterogeneity of GBM is implicated in treatment resistance, it remains unclear whether this diversity is observed within brain metastases and to what extent cancer cell–intrinsic heterogeneity sculpts the local immune microenvironment. Here, we profiled the immunogenomic state of 93 spatially distinct regions from 30 malignant brain tumors through whole-exome, RNA, and T-cell receptor sequencing. Our analyses identified differences between primary and secondary malignancies, with gliomas displaying more spatial heterogeneity at the genomic and neoantigen levels. In addition, this spatial diversity was recapitulated in the distribution of T-cell clones in which some gliomas harbored highly expanded but spatially restricted clonotypes. This study defines the immunogenomic landscape across a cohort of malignant brain tumors and contains implications for the design of targeted and immune-based therapies against intracranial malignancies.Significance:This study describes the impact of spatial heterogeneity on genomic and immunologic characteristics of gliomas and brain metastases. The results suggest that gliomas harbor significantly greater intratumoral heterogeneity of genomic alterations, neoantigens, and T-cell clones than brain metastases, indicating the importance of multisector analysis for clinical or translational studies.This article is highlighted in the In This Issue feature, p. 1

Co-expression of immune checkpoints in murine glioma

Purpose: T-cell dysfunction is a hallmark of glioblastoma (GBM). Although anergy and tolerance have been well characterized, T-cell exhaustion remains relatively unexplored. Exhaustion, characterized in part by the upregulation of multiple immune checkpoints, is a known contributor to failures amid immune checkpoint blockade, a strategy that has lacked success thus far in GBM. This study is among the first to examine, and credential as bona fide, exhaustion among T cells infiltrating human and murine GBM.Experimental Design: Tumor-infiltrating and peripheral blood lymphocytes (TILs and PBLs) were isolated from patients with GBM. Levels of exhaustion-associated inhibitory receptors and poststimulation levels of the cytokines IFNγ, TNFα, and IL2 were assessed by flow cytometry. T-cell receptor Vβ chain expansion was also assessed in TILs and PBLs. Similar analysis was extended to TILs isolated from intracranial and subcutaneous immunocompetent murine models of glioma, breast, lung, and melanoma cancers.Results: Our data reveal that GBM elicits a particularly severe T-cell exhaustion signature among infiltrating T cells characterized by: (1) prominent upregulation of multiple immune checkpoints; (2) stereotyped T-cell transcriptional programs matching classical virus-induced exhaustion; and (3) notable T-cell hyporesponsiveness in tumor-specific T cells. Exhaustion signatures differ predictably with tumor identity, but remain stable across manipulated tumor locations.Conclusions: Distinct cancers possess similarly distinct mechanisms for exhausting T cells. The poor TIL function and severe exhaustion observed in GBM highlight the need to better understand this tumor-imposed mode of T-cell dysfunction in order to formulate effective immunotherapeutic strategies targeting GBM. Clin Cancer Res; 24(17); 4175–86. ©2018 AACR.See related commentary by Jackson and Lim, p. 4059

Cytokine production across immunologic compartments

Gating strategy for tumor infiltrating lymphocytes

Immune checkpoint and cytokine expression on human GBM CD4+ TIL

T cell counts per gram of tumor across tumor models

Memory phenotype of human GBM TIL

T cell exhaustion in brain metastases models

Patient and Control Characteristics

Background Gliomas are the most common primary brain tumor in adults. Current treatments involve surgery, radiation, and temozolomide (TMZ) chemotherapy; however, prognosis remains poor and new approaches are required. Circadian medicine aims to maximize treatment efficacy and/or minimize toxicity by timed delivery of medications in accordance with the daily rhythms of the patient. We published a retrospective study showing greater anti-tumor efficacy for the morning, relative to the evening, administration of TMZ in patients with glioblastoma. We conducted this prospective randomized trial to determine the feasibility, and potential clinical impact, of TMZ chronotherapy in patients with gliomas (NCT02781792). Methods Adult patients with gliomas (WHO grade II-IV) were enrolled prior to initiation of monthly TMZ therapy and were randomized to receive TMZ either in the morning (AM) before 10 am or in the evening (PM) after 8 pm. Pill diaries were recorded to measure compliance and FACT-Br quality of life (QoL) surveys were completed throughout treatment. Study compliance, adverse events (AE), and overall survival were compared between the two arms. Results A total of 35 evaluable patients, including 21 with GBM, were analyzed (18 AM patients and 17 PM patients). Compliance data demonstrated the feasibility of timed TMZ dosing. There were no significant differences in AEs, QoL, or survival between the arms. Conclusions Chronotherapy with TMZ is feasible. A larger study is needed to validate the effect of chronotherapy on clinical efficacy.

Background Following chemoradiotherapy for high-grade glioma (HGG), it is often challenging to distinguish treatment changes from true tumor progression using conventional MRI. The diffusion basis spectrum imaging (DBSI) hindered fraction is associated with tissue edema or necrosis, which are common treatment-related changes. We hypothesized that DBSI hindered fraction may augment conventional imaging for earlier diagnosis of progression versus treatment effect. Methods Adult patients were prospectively recruited if they had a known histologic diagnosis of HGG and completed standard-of-care chemoradiotherapy. DBSI and conventional MRI data were acquired longitudinally beginning 4 weeks post-radiation. Conventional MRI and DBSI metrics were compared with respect to their ability to diagnose progression versus treatment effect. Results Twelve HGG patients were enrolled between August 2019 and February 2020, and 9 were ultimately analyzed (5 progression, 4 treatment effect). Within new or enlarging contrast-enhancing regions, DBSI hindered fraction was significantly higher in the treatment effect group compared to progression group (P = .0004). Compared to serial conventional MRI alone, inclusion of DBSI would have led to earlier diagnosis of either progression or treatment effect in 6 (66.7%) patients by a median of 7.7 (interquartile range = 0–20.1) weeks. Conclusions In the first longitudinal prospective study of DBSI in adult HGG patients, we found that in new or enlarging contrast-enhancing regions following therapy, DBSI hindered fraction is elevated in cases of treatment effect compared to those with progression. Hindered fraction map may be a valuable adjunct to conventional MRI to distinguish tumor progression from treatment effect.

Despite some success in secondary brain metastases, targeted or immune-based therapies have shown limited efficacy against primary brain malignancies such as glioblastoma (GBM). Although the intratumoral heterogeneity of GBM is implicated in treatment resistance, it remains unclear whether this diversity is observed within brain metastases and to what extent cancer cell–intrinsic heterogeneity sculpts the local immune microenvironment. Here, we profiled the immunogenomic state of 93 spatially distinct regions from 30 malignant brain tumors through whole-exome, RNA, and T-cell receptor sequencing. Our analyses identified differences between primary and secondary malignancies, with gliomas displaying more spatial heterogeneity at the genomic and neoantigen levels. In addition, this spatial diversity was recapitulated in the distribution of T-cell clones in which some gliomas harbored highly expanded but spatially restricted clonotypes. This study defines the immunogenomic landscape across a cohort of malignant brain tumors and contains implications for the design of targeted and immune-based therapies against intracranial malignancies. Significance: This study describes the impact of spatial heterogeneity on genomic and immunologic characteristics of gliomas and brain metastases. The results suggest that gliomas harbor significantly greater intratumoral heterogeneity of genomic alterations, neoantigens, and T-cell clones than brain metastases, indicating the importance of multisector analysis for clinical or translational studies. This article is highlighted in the In This Issue feature, p. 1

Many groups have reported lymphatic and glymphatic structures in animal and human brains, but tracer injection into the human brain to demonstrate real-time lymphatic drainage and mapping has not been described. We enrolled patients undergoing standard-of-care resection or stereotactic biopsy for suspected intracranial tumors. Patients received peritumoral injections of 99mTc-tilmanocept followed by planar or tomographic imaging. Fourteen patients with suspected brain tumors were enrolled. One was excluded from analysis because of tracer leakage during injection. There was no drainage of 99mTc-tilmanocept to regional lymph nodes in any of the patients. On average, after correcting for radioactive decay, 70.7% (95% CI: 59.9%, 81.6%) of the tracer in the injection site and 78.1% (95% CI: 71.1%, 85.1%) in the whole-head on the day of surgery remained the morning after, with variable radioactivity in the subarachnoid space. The retained fraction was much greater than expected based on the clearance rate from non-brain injection sites. In this pilot study, the lymphatic tracer 99mTc-tilmanocept was injected into the brain parenchyma, and there was no drainage outside the brain to the cervical lymph nodes. Our work demonstrates an inefficiency of drainage from peritumoral brain parenchyma and highlights a therapeutic opportunity to improve immunosurveillance of the brain.

BackgroundAdoptive cellular therapies with chimeric antigen receptor T cells have revolutionized the treatment of some malignancies but have shown limited efficacy in solid tumors such as glioblastoma and face a scarcity of safe therapeutic targets. As an alternative, T cell receptor (TCR)–engineered cellular therapy against tumor-specific neoantigens has generated significant excitement, but there exist no preclinical systems to rigorously model this approach in glioblastoma.MethodsWe employed single-cell PCR to isolate a TCR specific for the Imp3D81Nneoantigen (mImp3) previously identified within the murine glioblastoma model GL261. This TCR was used to generate the Mutant Imp3-Specific TCR TransgenIC (MISTIC) mouse in which all CD8 T cells are specific for mImp3. The therapeutic efficacy of neoantigen-specific T cells was assessed through a model of cellular therapy consisting of the transfer of activated MISTIC T cells and interleukin 2 into lymphodepleted tumor-bearing mice. We employed flow cytometry, single-cell RNA sequencing, and whole-exome and RNA sequencing to examine the factors underlying treatment response.ResultsWe isolated and characterized the 3×1.1C TCR that displayed a high affinity for mImp3 but no wild-type cross-reactivity. To provide a source of mImp3-specific T cells, we generated the MISTIC mouse. In a model of adoptive cellular therapy, the infusion of activated MISTIC T cells resulted in rapid intratumoral infiltration and profound antitumor effects with long-term cures in a majority of GL261-bearing mice. The subset of mice that did not respond to the adoptive cell therapy showed evidence of retained neoantigen expression but intratumoral MISTIC T cell dysfunction. The efficacy of MISTIC T cell therapy was lost in mice bearing a tumor with heterogeneous mImp3 expression, showcasing the barriers to targeted therapy in polyclonal human tumors.ConclusionsWe generated and characterized the first TCR transgenic against an endogenous neoantigen within a preclinical glioma model and demonstrated the therapeutic potential of adoptively transferred neoantigen-specific T cells. The MISTIC mouse provides a powerful novel platform for basic and translational studies of antitumor T-cell responses in glioblastoma.

BackgroundGlioblastoma is a fatal disease despite aggressive multimodal therapy. PD-1 blockade, a therapy that reinvigorates hypofunctional exhausted CD8 T cells (Tex) in many malignancies, has not shown efficacy in glioblastoma. Loss of CD4 T cells can lead to an exhausted CD8 T-cell phenotype, and terminally exhausted CD8 T cells (Texterm) do not respond to PD-1 blockade. GL261 and CT2A are complementary orthotopic models of glioblastoma. GL261 has a functional CD4 T-cell compartment and is responsive to PD-1 blockade; notably, CD4 depletion abrogates this survival benefit. CT2A is composed of dysfunctional CD4 T cells and is PD-1 blockade unresponsive. We leverage these models to understand the impact of CD4 T cells on CD8 T-cell exhaustion and PD-1 blockade sensitivity in glioblastoma.MethodsSingle-cell RNA sequencing was performed on flow sorted tumor-infiltrating lymphocytes from female C57/BL6 mice implanted with each model, with and without PD-1 blockade therapy. CD8+and CD4+T cells were identified and separately analyzed. Survival analyses were performed comparing PD-1 blockade therapy, CD40 agonist or combinatorial therapy.ResultsThe CD8 T-cell compartment of the models is composed of heterogenous CD8 Texsubsets, including progenitor exhausted CD8 T cells (Texprog), intermediate Tex, proliferating Tex, and Texterm. GL261 is enriched with the PD-1 responsive Texprogsubset relative to the CT2A and CD4-depleted GL261 models, which are composed predominantly of the PD-1 blockade refractory Textermsubset. Analysis of the CD4 T-cell compartments revealed that the CT2A microenvironment is enriched with a suppressive Tregsubset and an effector CD4 T-cell subset that expresses an inhibitory interferon-stimulated (Isc) signature. Finally, we demonstrate that addition of CD40 agonist to PD-1 blockade therapy improves survival in CT2A tumor-bearing mice.ConclusionsHere, we describe that dysfunctional CD4 T cells are associated with terminal CD8 T-cell exhaustion, suggesting CD4 T cells impact PD-1 blockade efficacy by controlling the severity of exhaustion. Given that CD4 lymphopenia is frequently observed in patients with glioblastoma, this may represent a basis for resistance to PD-1 blockade. We demonstrate that CD40 agonism may circumvent a dysfunctional CD4 compartment to improve PD-1 blockade responsiveness, supporting a novel synergistic immunotherapeutic approach.

BACKGROUND The blood brain barrier (BBB) remains a potential barrier to central nervous system (CNS) penetration of novel immunotherapies in recurrent glioblastoma (rGBM). Laser interstitial thermal therapy (LITT) was recently demonstrated to induce BBB disruption. When combined with anti-PD1 blockade, LITT may therefore potentiate host T-cell mediated cytotoxicity. This phase I/II study aims to evaluate the safety and efficacy of combining LITT and the PD-1 inhibitor pembrolizumab for rGBM. METHODS Phase I treated eligible bevacizumab-naïve high grade glioma patients with LITT and the anti-PD1 inhibitor pembrolizumab at 3 dose levels (100, 150, and 200 mg IV Q3W; 3 patients at each level), while phase II was restricted to rGBM patients only with the recommended phase II dose (RP2D) of pembrolizumab. Phase II was initially designed to randomize rGBM to either pembrolizumab or pembrolizumab+LITT but was later amended to receive only pembrolizumab+LITT after 16 patients were randomized (10 pembrolizumab+LITT arm, 6 pembrolizumab-alone arm). Progression-free survival (PFS) and overall survival (OS) were evaluated using the Kaplan Meier method, and adverse events (AE) documented. RESULTS Phase I enrolled 9 patients (7 rGBM and 2 anaplastic astrocytomas, 33% IDH-mut, 44% MGMTp-methylated) with no dose limiting toxicities (DLT), prompting selection of 200mg Q3W as the RP2D. Phase II interim analysis included 34 rGBM patients (9% IDH-mut, 50% MGMTp-methylated; 6 receiving pembrolizumab alone and 28 pembrolizumab+LITT) plus two Phase I rGBM patients who received RP2D. On per-protocol analysis, pembrolizumab+LITT cohort had improved PFS (median PFS 10.5 months vs 2.1 months) and OS (median OS 11.4 months vs 5.2 months) than pembrolizumab alone. A single treatment-related grade 3 AE was noted (respiratory infection). CONCLUSION: LITT may be safely combined with pembrolizumab for rGBM with promising clinical outcomes on interim analysis. Enrollment for Phase II, correlative studies, and continued AE documentation are ongoing. Clinical Trial ID NCT02311582.

BackgroundTumor neoantigens are epitopes derived from tumor-specific mutations. Such mutations can be incorporated in personalized vaccines to prime T cell responses against tumor specific antigens. DNA vaccines delivered with electroporation have recently shown strong CD8 and CD4 T cell responses in clinical trials. In preclinical studies, DNA-encoded neoantigen vaccines have shown induction of CD8 T cells against 50% of predicted high affinity epitopes with the ability to impact tumor growth.MethodsTwo resection samples from a patient with IDH+ MGMT-methylated anaplastic astrocytoma were subject to whole exome and transcriptome sequencing. Epitopes derived from 27 neoantigens and 3 shared tumor-associated antigens were prioritized and included in a personalized vaccine. The patient was treated with surgery, radiotherapy and temozolomide starting June 2018 and received the first dose of the personalized vaccine in June 2019 under a compassionate use single patient IND application with the FDA.ResultsAs of July 23rd, 2021, the patient has received 11 doses of the DNA personalized vaccine. No serious adverse events have been reported. Related adverse events are limited to grade 1 injection site reactions. The patient remains progression-free 37 months after surgery and 25 months after starting vaccination. Three weeks following the 3rd dose, a hyperintense image on the tumor bed was identified, which disappeared on the following MRI, 2 weeks following dose 5, being catalogued as pseudo progression. Ex vivo ELISpot have identified T cell responses to 28/30 epitopes (93.3%), including 25/27 (92.6%) neoantigens and 3/3 (100%) shared antigens. Flow cytometry analysis has determined that T cell responses are 92.3% CD8 and 69.2% CD4 (30.8% CD8 only; 61.5% both CD8 and CD4; and 7.7% CD4 only).ConclusionsThis compassionate use treatment in an adjuvant setting demonstrates manufacturing feasibility, safety, tolerability, immunogenicity, and suggests potential for persistent clinical response of DNA encoded personalized vaccines. The data supports further investigation of DNA-encoded personalized vaccines into newly diagnosed high-grade gliomas.Ethics ApprovalThe study was approved by Washington University's IRB. The participant gave informed consent before taking part in the study.

Malignant gliomas are the most common primary brain cancer diagnosed and still carry a poor prognosis despite aggressive multimodal management. Despite the continued advances in immunotherapy for other cancer types, however, there remain no FDA approved immunotherapies for cancers such as glioblastoma. OF the many approaches being explored, cancer vaccine programs are undergoing a renaissance due to the technological advances and personalized nature of their contemporary design. Neoantigen vaccines are a form of immunotherapy involving the use of DNA, mRNA, and proteins derived from non-synonymous mutations identified in patient tumor tissue samples to stimulate tumor-specific T-cell reactivity leading to enhance tumor targeting. In the last several years, the study of neoantigens as a therapeutic target has increased, with the routine workflow implementation of comprehensive next generation sequencing and in silico peptide binding prediction algorithms. Several neoantigen vaccine platforms are being evaluated in clinical trials for malignancies including melanoma, pancreatic cancer, breast cancer, lung cancer, and glioblastoma, among others. In this review, we will review the concept of neoantigen discovery using cancer immunogenomics approaches in glioblastoma and explore the disease-specific issues being addressed in the design of effective personalized cancer vaccine strategies.

The central nervous system (CNS) antigen presenting cell (APC) which primes anti-tumor CD8+ T cell responses remains undefined. Elsewhere, the conventional dendritic cell 1 (cDC1) performs this role. However, steady-state brain cDC1 are rare; cDC localize to choroid plexus and dura. Using preclinical glioblastoma models and cDC1-deficient mice, we explored the role of cDC1 in CNS anti-tumor immunity. We determined that cDC1 mediate checkpoint blockade-induced survival benefit and prime neoantigen-specific CD8+ T cells against brain tumors. We observed that cDC, including cDC1, isolated from the tumor, the dura, and the CNS-draining cervical lymph nodes harbored a traceable fluorescent tumor-antigen. In patient samples, we observed several APC subsets (including the CD141+ cDC1-equivalent) infiltrating glioblastomas, meningiomas, and dura. In these same subsets, we identified a tumor-specific fluorescent metabolite of 5- aminolevulinic acid, which labels tumor cells during fluorescence-guided glioblastoma resection. Together, these data elucidate the specialized behavior of cDC1 and suggest cDC1 play a significant role in CNS anti-tumor immunity.One Sentence SummaryCNS cDC1 engage in previously undefined behavior to establish immune responses against brain tumors.

The introduction of immune checkpoint blockade (ICB) and BRAF-MEK inhibitors has substantially improved outcomes in patients with metastatic melanoma. However, several challenging factors may hinder the efficacy of ICB in patients with symptomatic intracranial metastatic melanoma who are immunosuppressed due to the use of steroids prior to the administration of ICB. This has resulted in the exclusion of patients treated with high dose steroid at baseline from the majority of ICB clinical trials. In addition, despite the high efficacy of BRAF-MEK inhibitors in BRAF-mutant intracranial metastatic melanoma, most tumors will eventually progress. This demonstrates a gap in addressing the best management in such patients. Here, we present a case demonstrating our approach in this patient population., Tweetable abstract Management of symptomatic BRAF-mutated intracranial melanoma.

Purpose Glioblastoma (GBM) remains incurable, despite state-of-the-art treatment involving surgical resection, chemotherapy, and radiation. GBM invariably recurs as a highly invasive and aggressive phenotype, with the majority of recurrences within the radiation therapy treatment field. Although a large body of literature reporting on primary GBM exists, comprehensive studies of how prior irradiation alters recurrent tumor growth are lacking. An animal model that replicates the delayed effects of radiation therapy on the brain microenvironment, and its impact on the development of recurrent GBM, would be a significant advance. Methods and Materials Cohorts of mice received a single fraction of 0, 20, 30, or 40 Gy Gamma Knife irradiation. Naive, nonirradiated mouse GBM tumor cells were implanted into the ipsilateral hemisphere 6 weeks postirradiation. Tumor growth was measured by magnetic resonance imaging, and animal survival was assessed by monitoring weight loss. Magnetic resonance imaging results were supported by hemotoxylin and eosin histology. Results Tumorous lesions generated from orthotopic implantation of nonirradiated mouse GBM tumor cells into irradiated mouse brain grew far more aggressively and invasively than implantation of these same cells into nonirradiated brain. Lesions in irradiated brain tissue were significantly larger, more necrotic, and more vascular than those in control animals with increased invasiveness of tumor cells in the periphery, consistent with the histologic features commonly observed in recurrent high-grade tumors in patients. Conclusions Irradiation of normal brain primes the targeted cellular microenvironment for aggressive tumor growth when naive (not previously irradiated) cancer cells are subsequently introduced. The resultant growth pattern is similar to the highly aggressive pattern of tumor regrowth observed clinically after therapeutic radiation therapy. The mouse model offers an avenue for determining the cellular and molecular basis for the aggressiveness of recurrent GBM.

Neoantigens are novel peptide sequences resulting from somatic mutations in tumors that upon loading onto major histocompatibility complex (MHC) molecules allow recognition by T cells. Accurate neoantigen identification is thus critical for designing cancer vaccines and predicting response to immunotherapies. Neoantigen identification and prioritization relies on correctly inferring whether the presenting peptide sequence can successfully induce an immune response. As the majority of somatic mutations are SNVs, changes between wildtype and mutant peptide are subtle and require cautious interpretation. An important, yet underappreciated, variable in neoantigen-prediction pipelines is the mutation position within the peptide relative to its anchor positions for the patient’s specific HLA alleles. While a subset of peptide positions are presented to the T-cell receptor for recognition, others are responsible for anchoring to the MHC, making these positional considerations critical for predicting T-cell responses. However, a systematic method for determining anchor locations for the wide range of HLA alleles present in the population and application of these to evaluate MT/WT peptide pairs arising in tumors has not been reported. As a result, many neoantigen studies have either failed to adequately consider this crucial factor or have used conventional assumptions to guide their neoantigen identification process. Here, we provide a computational workflow for predicting anchor locations for a wide range of HLA alleles, using a reference dataset generated from clinical and The Cancer Genome Atlas (TCGA) patient samples. We calculated high probability anchor positions for different peptide lengths for over 300 common HLA alleles. Analysis of these results showed clusters of different anchor trends among the HLA alleles analyzed. A subset of these HLA anchor results were orthogonally validated using protein crystallography structures. Analysis of 923 tumor samples showed that 7-41% of neoantigen candidates were potentially misclassified in the neoantigen selection process and can be rescued using allele-specific knowledge of anchor positions. These anchor predictions are currently undergoing experimental validation using both peptide-MHC stability assays as well as fluorescence-based competition binding assays. By incorporating our anchor prediction results into neoantigen prediction pipelines, such as pVACtools, we hope to formalize and streamline the identification process for relevant clinical studies. Citation Format: Huiming Xia, Joshua McMichael, Michelle Becker-Hapak, Onyinyechi C. Onyeador, Rico Buchli, Ethan McClain, Patrick Pence, Suangson Supabphol, Megan M. Richters, Anamika Basu, Cody A. Ramirez, Cristina Puig-Saus, Kelsy C. Cotto, Jasreet Hundal, Susanna Kiwala, S. Peter Goedegebuure, Tanner M. Johanns, Gavin P. Dunn, Antoni Ribas, Christopher A. Miller, William Gillanders, Todd A. Fehniger, Obi L. Griffith, Malachi Griffith. Computational prediction of MHC anchor locations guide neoantigen prediction and prioritization [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5639.

Background: Oncolytic viruses selectively infect tumors and activate antitumor immune responses via innate and adaptive pathways, leading to immunogenic cell death and potentiating the efficacy of immune checkpoint inhibitors. MEDI9253 is a recombinant Newcastle disease virus (NDV) that incorporates a human transgene encoding the immunostimulatory cytokine interleukin (IL)-12, which leads to tumor cell lysis and localized IL-12 expression. Preclinical studies show that MEDI9253 induces PD-L1 expression and recruits innate and adaptive immune cells to the tumor microenvironment (TME) and indicate that its antitumor activity is enhanced by concurrent PD-L1 blockade. This clinical study is evaluating intravenous (IV) MEDI9253 in combination with the anti-PD-L1 antibody durvalumab in patients with selected advanced solid tumors. Methods: This is a phase I, multicenter, open-label, dose escalation and dose expansion trial (NCT04613492) enrolling patients with microsatellite-stable colorectal cancer (MSS-CRC), renal cell carcinoma (RCC) or melanoma. Eligibility criteria include progressed/refractory disease or intolerance to all prior lines of therapy with proven survival benefit for recurrent/metastatic disease. Patients must have life expectancy ≥12 weeks by GRIm score; histologically documented disease; adequate performance status (ECOG 0-1); adequate organ function; and presence of RECIST v1.1 measurable disease amenable to repeated biopsy. Exclusion criteria include untreated/uncontrolled metastatic CNS involvement. Patients must take precautions to prevent the theoretical risk of NDV transmission to humans and birds. The trial will enroll up to ~192 patients across 30 centers globally. The dose escalation phase will evaluate a single dose of IV MEDI9253 with sequential IV durvalumab, then multiple-dose cohorts of up to 4 ascending dose levels of MEDI9253 with sequential or concurrent durvalumab. The dose expansion phase will include 3 cohorts of ~20 patients, each enrolling a single tumor type. In both phases, durvalumab will be dosed for up to 2 years or until disease progression, clinical deterioration, withdrawal of consent or unacceptable toxicity. Pretreatment and on-treatment tumor biopsies are required for patients in multiple-dose cohorts. The primary objectives are evaluating the safety, tolerability and incidence of dose-limiting toxicities of MEDI9253 and identifying the optimal dose/schedule in combination with durvalumab. Secondary objectives include assessing initial efficacy (response and progression-free survival by RECIST v1.1, and overall survival), pharmacodynamics in the TME, immunogenicity, and pharmacokinetics (viremia and IL-12). The trial is recruiting. Citation Format: Noelia Purroy, Nicholas Durham, Marc Phillips, Maureen M. Hattersley, Lindsey Jung, Diwakar Davar, Dmitriy Zamarin, Tanner M. Johanns, Igor Puzanov. First-in-human trial of intravenous MEDI9253, an oncolytic virus, in combination with durvalumab in patients with advanced solid tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr CT218.

We compared the performance of two 96-well multiplex immunoassay platforms in assessing plasma cytokine concentrations in patients with glioblastoma (GBM; n = 27), individuals with melanoma, breast or lung cancer metastases to the brain (n = 17), and healthy volunteers (n = 11). Assays included a bead-based fluorescence MILLIPLEX® assay/Luminex (LMX) platform and 4 planar electrochemiluminescence kits from Meso Scale Discovery (MSD). The LMX kit evaluated 21 cytokines and the 3 MSD kits evaluated 20 cytokines in total, with 19 overlapping human cytokines between platforms (GM-CSF, IFNγ, IL-1β, IL-2, IL-4, IL-5, IL-6, IL-7, IL-8, IL-10, IL-12p70, IL-13, IL-17A, IL-21, IL-23, MIP-1α, MIP-1β, MIP-3α, TNFα). The MSD platform had lower LLoQs (lower limits of quantification) than LMX for 17/19 cytokines, and higher LLoQs for IFN-γ and IL-21. The ULoQs were higher in LMX versus MSD assays for 17/19 shared analytes, but lower than MSD for IL-17A and IL-21. With LMX, all 19 shared analytes were quantifiable in each of 55 samples. Although MSD recombinant protein standard curves indicated lower LLoQs than LMX for most cytokines, MSD detected 7/19 (37%) native analytes in

Purpose/Objective(s) Immune checkpoint inhibitors (CPIs) and BRAF inhibitors (BIs) are standard treatments for metastatic melanoma and have intracranial activity against melanoma brain metastases (MBMs). However, optimal use of CPI/BI with radiation therapy (RT) is not well established. This study evaluates the current practice pattern of how these systemic therapies are chosen and combined with either whole brain radiation therapy (WBRT) or stereotactic radiosurgery (SRS) for MBMs. The study also examines if upfront SRS+CPI results in superior intracranial control (IC) than upfront SRS without CPI or upfront CPI/BI followed by salvage RT. Materials/Methods Patients with MBMs who received their first course of intracranial RT with between 1/2014 and 12/2019 at a tertiary cancer center were retrospectively reviewed. Patients with leptomeningeal disease and MBMs from non-cutaneous melanoma were excluded. Prior exposure before MBM diagnosis and concomitant use of CPIs/BIs within 3 months of RT were evaluated. Binary logistic regression was performed to determine predictors of SRS or CPI use. Cox regression analysis was used to assess the association with IC, which was calculated from the time of MBM diagnosis to the first intracranial progression after upfront MBM treatment. Results A total of 123 patients with MBMs with a median age of 61 (IQR: 51-69) were identified, and 55% were BRAF-mutant. There were 75 patients (61%) with 1-4 MBMs, 31 patients (25%) with 5-10 MBMs, and 17 (14%) patients with > 10 MBMs. Before MBM diagnosis, 30% had prior CPI and 18% had prior BI. For the upfront MBM treatment, 64% received SRS (66% with CPI and 23% with BI), 27% received WBRT (42% with CPI and 30% with BI), 9% received upfront CPI/BI. The baseline characteristics were balanced between the patients who received upfront SRS and upfront CPI/BI except patients who received upfront CPI/BI were more likely to have a BRAF mutation (82% vs. 49%, P = 0.04). The median follow-up was 8.7 mo (IQR: 2.8-22) for all patients and 32 mo (IQR: 18-45) for living patients. For patients who received upfront CPI/BI, 73% underwent salvage SRS and 27% with salvage WBRT at a median of 5.7 mos [IQR: 3.0-7.7] after MBM diagnosis. Fewer number of MBMs, higher KPS, and craniotomy were significant predictors of SRS use on multivariable logistic regression. For the upfront SRS cohort, treatment after 2016, BRAF-wild type status, and prior CPI exposure were associated with higher likelihood of concomitant CPI use with SRS. After adjusting for the number of MBMs, upfront SRS+CPI was associated with higher IC than upfront SRS without CPI (HR: 0.43, 95% CI: 0.22-0.84, P = 0.02). Upfront SRS+ CPI also trended towards a higher IC than upfront CPI/BI with salvage RT (HR: 0.54, 95% CI: 0.27-1.1, P = 0.07) after adjusting for the number of MBMs. Conclusion Upfront SRS with concomitant CPI was the most frequently used approach to treat newly diagnosed favorable MBMs and may yield superior IC than upfront SRS without CPI or upfront CPI/BI. Author Disclosure R. Chin: None. K. Chen: None. C.D. Abraham: None. C.G. Robinson: Research Grant; Varian. Consultant; Varian, AstraZeneca, EMD Serono. Advisory Board; Radialogica. Stock Options; Radialogica. S.M. Perkins: I serve on the Medical Advisory Committee for Mevion Medical Systems and receive compensation for this role.; Mevion Medical Systems. T.M. Johanns: None. L.F. Hernandez-Aya: None. J.W. Keller: None. J. Dowling: None. K. Rich: None. M. Chicoine: None. A.H. Kim: None. G.P. Dunn: None. G. Ansstas: None. J. Huang: None.

Background Optimal management for recurrent IDH-mutant glioma after radiation therapy (RT) is not well-defined. This study assesses practice patterns for managing recurrent IDH-mutant astrocytoma (Astro) and 1p/19q codeleted oligodendroglioma (Oligo) after RT and surveys their clinical outcomes after different salvage approaches. Methods Ninety-four recurrent Astro or Oligo patients after RT who received salvage systemic therapy (SST) between 2001 and 2019 at a tertiary cancer center were retrospectively analyzed. SST was defined as either alkylating chemotherapy (AC) or nonalkylating therapy (non-AC). Overall survival (OS) and progression-free survival (PFS) were calculated using the Kaplan-Meier method from the start of SST. Multivariable analysis (MVA) was conducted using Cox regression analysis. Results Recurrent Oligo (n = 35) had significantly higher PFS (median: 3.1 vs 0.8 years, respectively, P = .002) and OS (median: 6.3 vs 1.5 years, respectively, P < .001) than Astro (n = 59). Overall, 90% of recurrences were local. Eight-three percent received AC as the first-line SST; 50% received salvage surgery before SST; approximately 50% with local failure >2 years after prior RT received reirradiation. On MVA, non-AC was associated with worse OS for both Oligo and Astro; salvage surgery was associated with improved PFS and OS for Astro; early reirradiation was associated with improved PFS for Astro. Conclusions Recurrent radiation-relapsed IDH-mutant gliomas represent a heterogeneous group with variable treatment approaches. Surgery, AC, and reirradiation remain the mainstay of salvage options for retreatment.

Neoantigens are novel peptide sequences resulting from sources such as somatic mutations in tumors. Upon loading onto major histocompatibility complex (MHC) molecules, they can trigger recognition by T cells. Accurate neoantigen identification is thus critical for both designing cancer vaccines and predicting response to immunotherapies. Neoantigen identification and prioritization relies on correctly predicting whether the presenting peptide sequence can successfully induce an immune response. As the majority of somatic mutations are single nucleotide variants, changes between wildtype and mutated peptides are typically subtle and require cautious interpretation. A potentially underappreciated variable in neoantigen-prediction pipelines is the mutation position within the peptide relative to its anchor positions for the patient’s specific MHC molecules. While a subset of peptide positions are presented to the T-cell receptor for recognition, others are responsible for anchoring to the MHC, making these positional considerations critical for predicting T-cell responses. We computationally predicted high probability anchor positions for different peptide lengths for 328 common HLA alleles and identified unique anchoring patterns among them. Analysis of 923 tumor samples shows that 6-38% of neoantigen candidates are potentially misclassified and can be rescued using allelespecific knowledge of anchor positions. A subset of anchor results were orthogonally validated using protein crystallography structures. Representative anchor trends were experimentally validated using peptide-MHC stability assays and competition binding assays. By incorporating our anchor prediction results into neoantigen prediction pipelines, we hope to formalize, streamline and improve the identification process for relevant clinical studies.One Sentence SummaryNeoantigen prediction accuracy is significantly influenced by the mutation position within the neoantigen and its relative position to the patient’s allele-specific MHC anchor locations.

Background The ongoing SURPASS trial (NCT04044859) evaluates safety and efficacy of next-generation ADP-A2M4CD8 SPEAR T-cells co-expressing the CD8α co-receptor with the engineered MAGE-A4c1032T cell receptor (TCR). Methods First-in-human trial in HLA-A*02 positive patients (pts) with advanced cancers expressing MAGE-A4 antigen by immunohistochemistry. Eligible pts undergo apheresis, T-cells are isolated, transduced with a Lentiviral vector containing the MAGE-A4c1032 TCR and CD8α co receptor, and expanded. Expansion, transduction level, cellular composition and function of the manufactured product (MP) are assessed in vitro. Prior to infusion, pts receive lymphodepletion with fludarabine 30 mg/m2/day for 4 days and cyclophosphamide 600 mg/m2/day for 3 days. Results As of 16 July 2020, 5 pts (1 with MRCLS, 2 with esophagogastric junction [EGJ] cancers, 1 with ovarian cancer, and 1 with head and neck cancer) were treated with ADP-A2M4 CD8 (range ~1 to 5.7 billion transduced cells). No DLTs or SAEs have been reported. To date, 1 pt with EGJ cancer had a partial response (PR per RECIST) and has had progression-free survival >6 months. One pt with head and neck cancer also had a PR. All other pts have had best overall response of stable disease.MP expanded by an average of 15.3 fold during manufacturing (range 5.9 to 25.6-fold). On average, 43% of T-cells in the MP expressed the TCR (range 23 to 63%). The fraction of CD4+ cells in the final MP varied (range 45 to 84%). Co-expression of the MAGE-A4 TCR and CD8α in CD4+ T-cells in the patient MP enabled CD4+ T-cells to kill tumor target cells directly in vitro. MAGE-A4 expression in tumor biopsies varied (H-score range 55 to 300). Transduced T-cells were detected in peripheral blood of all pts. IFN-gamma increased transiently in the serum of 1 pt who responded. Conclusions ADP-A2M4CD8 SPEAR T-cells have shown an acceptable safety profile and pts with EGJ cancer and head and neck cancer have demonstrated evidence of antitumor activity. Translational data and early clinical results indicate that co-expression of the CD8α co-receptor on CD4+ SPEAR T-cells may increase the potency of the product by conferring additional killing activity to the helper T-cell subset. This dose escalation trial is ongoing and updated clinical and translational data will be presented. Trial Registration NCT04044859 Ethics Approval The trial was conducted in accordance with the principles of the Declaration of Helsinki and the International Conference on Harmonization Good Clinical Practice guidelines and was approved by local authorities. An independent ethics committee or institutional review board approved the clinical protocol at each participating center. All the patients provided written informed consent before study entry.

Encouraging clinical results using immune checkpoint therapies to target the PD-1 axis in a variety of cancer types have paved the way for new immune therapy trials in brain tumor patients. However, the molecular mechanisms that regulate expression of the PD-1 pathway ligands, PD-L1 and PD-L2, remain poorly understood. To address this, we explored the cell-intrinsic mechanisms of constitutive PD-L1 and PD-L2 expression in brain tumors. PD-L1 and PD-L2 expression was assessed by flow cytometry and qRT-PCR in brain tumor cell lines and patient tumor-derived brain tumor-initiating cells (BTICs). Immunologic effects of PD-L2 overexpression were evaluated by IFN-γ ELISPOT. CD274 and PDCD1LG2 cis-regulatory regions were cloned from genomic DNA and assessed in full or by mutating and/or deleting regulatory elements by luciferase assays. Correlations between clinical responses and PD-L1 and PD-L2 expression status were evaluated in TCGA datasets in LGG and GBM patients. We found that a subset of brain tumor cell lines and BTICs expressed high constitutive levels of PD-L1 and PD-L2 and that PD-L2 overexpression inhibited neoantigen specific T cell IFN-γ production. Characterization of novel cis-regulatory regions in CD274 and PDCD1LG2 lead us to identify that GATA2 is sufficient to drive PD-L1 and PD-L2 expression and is necessary for PD-L2 expression. Importantly, in TCGA datasets, PD-L2 correlated with worse clinical outcomes in glioma patients.. By perturbing GATA2 biology, targeted therapies may be useful to decrease inhibitory effects of PD-L2 in the microenvironment.

Glioblastoma is a devastating disease with a dismal prognosis. While recent advancements in cancer immunotherapy have led to improvements in treating other types of cancer, patients with glioblastoma have not benefited from these new therapies and techniques. Fortunately, neurosurgeons and oncologists at Washington University School of Medicine conducting a cutting edge clinical trial are looking to overcome these persistent challenges in treating glioblastoma through combining a personalized vaccine with new immunotherapy drugs.