Patient Tumor Biopsies Research Articles

Targeting transforming growth factor-β1 by methylseleninic acid/seleno-L-methionine in clear cell renal cell carcinoma: Mechanisms and therapeutic potential.

Clear cell renal cell carcinoma (ccRCC) poses a significant global health challenge as its incidence continues to rise, resulting in a substantial annual mortality rate. Major clinical challenges to current ccRCC treatments include high drug-resistance rates as well as dose-limiting adverse events; underlining the need to identify additional 'druggable' targets. TGF-β1, VEGF, and PD-L1 are potential therapeutic targets in ccRCC. This study analyzed their expression in human ccRCC cell lines and patient tumor biopsies. Data obtained from western blotting demonstrated higher levels of TGF-β1 and PD-L1 and lower levels of VEGF in sarcomatoid ccRCC cell lines compared to non-sarcomatoid ccRCC cell lines. In patient samples, TGF-β1 was significantly upregulated in both non-sarcomatoid and sarcomatoid ccRCC tumors. It was demonstrated through two assays (cellular thermal shift assay and a size exclusion assay) that methylseleninic acid (MSA) binds specifically and directly to TGF-β1. MSA treatment significantly downregulated TGF-β1, PD-L1, and VEGF in a dose- and time-dependent manner in both non-sarcomatoid and sarcomatoid ccRCC cell lines. Seleno-L-methionine (SLM) treatment in a nude mouse xenograft model showed a significant tumor growth inhibition and TGF-β1 downregulation at non-toxic doses. These findings suggest that selenium-mediated downregulation of TGF-β1, PD-L1, and VEGF could be a viable therapeutic strategy for ccRCC.

Tumor-derived G-CSF induces an immunosuppressive microenvironment in an osteosarcoma model, reducing response to CAR.GD2 T-cells

Sarcomas are rare, mesenchymal tumors, representing about 10–15% of all childhood cancers. GD2 is a suitable target for chimeric antigen receptor (CAR) T-cell therapy due to its overexpression in several solid tumors. In this preclinical study, we investigated the potential use of iCasp9.2A.GD2.CAR-CD28.4–1BBζ (CAR.GD2) T-cells as a treatment option for patients who have GD2-positive sarcomas and we sought to identify factors shaping hostile tumor microenvironment in this setting. GD2 expression was evaluated by flow-cytometry on primary tumor biopsies of pediatric sarcoma patients. GD2 expression in sarcoma cells was also evaluated in response to an enhancer of zeste homolog 2 (EZH2) inhibitor (Tazemetostat). The antitumor activity of CAR.GD2 T-cells was evaluated both in vitro and in vivo preclinical models of orthotopic and/or metastatic soft-tissue and bone sarcomas. GD2 expression was detected in 55% of the primary tumors. Notably, the Osteosarcoma and Alveolar Rhabdomyosarcomas subtypes exhibited the highest GD2 expression levels, while Ewing sarcoma showed the lowest. CAR.GD2 T-cells show a significant tumor control both in vitro and in vivo models of GD2-expressing tumors. Pretreatment with an EZH2 inhibitor (Tazemetostat) upregulating GD2 expression, sensitizes GD2dim sarcoma cells to CAR.GD2 T-cells cytotoxic activity. Moreover, in mouse models of disseminated Rhabdomyosarcomas and orthotopic Osteosarcoma, CAR.GD2 T-cells showed both a vigorous anti-tumor activity and long-term persistence as compared to un-transduced T-cells. The presence of immunosuppressive murine myeloid-derived suppressor (MDSC) cells significantly reduces long-term anti-tumour activity of infused CAR.GD2 T-cells. Tumor-derived G-CSF was found to be one of the key factors driving expansion of immunosuppressive murine and human MDSC, thus indirectly limiting the efficacy of CAR.GD2 T-cells. Our preclinical data strongly suggest that CAR.GD2 T-cells hold promise as a potential therapeutic option for the treatment of patients with GD2-positive sarcomas. Strategies to tackle hostile immunosuppressive MDSC are desirable to optimize CAR.GD2 T-cell activity.

TMET-30. ONCOLYTIC HSV REWIRES METABOLISM TO PROMOTE ANTITUMOR IMMUNITY THROUGH REDUCTIVE CARBOXYLATION AND FERROPTOSIS

Abstract Cancer cells autonomously rewire metabolism to meet increased bioenergetic demands. Oncolytic HSVs (oHSVs) are attenuated Herpes simplex type 1 derived viruses that lyse tumor cells releasing damage-associated molecules triggering antitumor immunity. Currently one oHSV-1 derived virus is approved for melanoma treatment in the USA and another for recurrent GBM in Japan. While several other viruses are being evaluated in clinical trials for safety and efficacy, an understanding of the impact of oHSV therapy on cancer cell metabolism is largely unexplored. A detailed understanding of how oHSV impact tumor cell metabolism and oxidative stress is important to understand the unique susceptibilities that can further be exploited to improve the therapeutic index. Here, we analyzed transcriptomic changes in tumor biopsies of recurrent high-grade glioma patients treated with oHSV. RNA-seq data obtained from pre- and post-G207 treated biopsies from phase-Ib study patients (NCT00028158) revealed enrichment in pathways related to citric acid cycle, oxidative phosphorylation, and glutamate metabolism. We confirmed these changes by RNA sequencing of oHSV-infected patient derived GBM cells. Mechanistically, oHSV hijacked cellular glucose metabolism to increase oxidative phosphorylation and modulated cellular glutamine metabolism towards reductive carboxylation and reduced free glutathione, collectively contributing to increased ROS generation. Kinome profiling revealed PKC activation upon treatment with oHSV. Increased ROS combined with reduced glutathione, and PKC activation promoted ferroptotic cell death characterized by increased lipid peroxidation and smaller, ruptured mitochondria, and contributed to immunotherapy by this treatment. IDH mutant tumors that block reductive carboxylation were resistant to oHSV-induced ferroptotic cell death and did not benefit from oHSV-induced antitumor benefit. Together, this study presents avenues to enhance antitumor immunity by oHSV therapy.

Fecal, duodenal, and tumor microbiota composition of esophageal carcinoma patients, a longitudinal prospective cohort.

The microbiome has been associated with chemotherapy and immune checkpoint inhibitor efficacy. How this pertains to resectable esophageal carcinoma is unknown. Our aim was to identify microbial signatures in resectable esophageal carcinoma associated with response to neoadjuvant chemoradiotherapy with or without an immune checkpoint inhibitor. From 2 prospectively collected esophageal carcinoma cohorts (n = 172 in total) treated with neoadjuvant chemoradiotherapy alone (n = 132) or a combination of neoadjuvant chemoradiotherapy and an immune checkpoint inhibitor (n = 40), fecal samples were available at baseline, during treatment, and presurgery. Additionally, in the immune checkpoint inhibitor-treated patients, tumor and duodenal snap frozen biopsies were collected over time. Fecal, tumor, and duodenal DNA were extracted for 16S ribosomal RNA sequencing. Associations were investigated between microbiome composition pathological complete response and progression-free survival (PFS). There was a statistically significant shift in the microbiota profile of the fecal, tumor, and duodenal microbiota over time. In the total cohort, patients with a pathological complete response had a stable fecal alpha diversity, while the diversity of poor responders decreased during treatment (P = .036). Presurgery, lower alpha diversity (<4.12) was related to worse PFS (log-rank P = .025). Baseline tumor biopsies of patients with short PFS had more Fusobacterium. A low baseline duodenal alpha diversity (<3.96) was associated with worse PFS (log-rank P = .012). Lower intestinal alpha diversity was associated with worse response and survival of esophageal carcinoma patients. In tumor biopsies, Fusobacterium was more abundant in patients with poor PFS. After further mechanistic validation, these findings may aid in response prediction and the design of novel microbiome modulating treatments for esophageal carcinoma patients.

Abstract PO5-14-06: Transcriptomics-based drug screening in 3D ex vivo patient-derived breast cancer model and patient biopsy for personalized therapy

Abstract Breast cancer is a leading cause of cancer-related mortality for women worldwide. Hormone receptor-positive (HR+) breast tumors, which represent 70% of all breast cancer cases, are treated with endocrine therapy. However, not all patients benefit from this treatment regimen because of patient-to-patient variation. Therefore, high throughput drug screening system is warranted to enable personalized medicine. Patient-derived organoids, which serve as a screening platform, lose their hormone receptors and response upon ex vivo culturing, and may not be adequate models for HR+ breast tumors. Moreover, unidentified biological components in the widely-used basement membrane matrix, Matrigel, result in high batch-to-batch variations and poor reproducibility in organoid cultures. Here, we propose a hydrogel-based 3D ex vivo model with defined structural and chemical properties to test hormone and drug sensitivity of HR+ breast tumors from patient-derived xenografts (PDXs) and patient tumor biopsies using microfluidics. Our data demonstrate the feasibility of this model to preserve cell proliferation and hormone receptor expression over 7 days. We also demonstrate that responses to hormones and FDA-approved drugs are faithfully maintained in this model. Finally, to establish a high throughput hormone and drug testing workflow with transcriptomic readout, we multiplexed barcoded- and drug-treated tumor samples in a single experiment with bulk RNA-sequencing. Our preliminary data demonstrate patient-specific responses to hormones and drugs that correspond to patient genetic mutation profiles, treatment history, disease stages and subtypes. This platform also enables testing of drugs in clinical trials that shows promising therapeutic outcomes for breast cancer, such as CDK4/6i, AKTi, PARPi, mTORi and their combination with endocrine therapy, thanks to the high throughput of the screening system and the low consumption of patient-derived or patient tissue. Given the capability of combining this physiologically-relevant 3D ex vivo model with RNA-seq for HR+ breast tumors, this platform holds potential for high throughput compound testing and transcriptomic profiling of patient biopsies for personalized medicine. Citation Format: Yueyun Zhang, Carlos Henrique Venturi Ronchi, Giovanna Ambrosini, Yuanlong Liu, Patrick Aouad, Daria Matvienko, Christoph Merten, Cathrin Brisken. Transcriptomics-based drug screening in 3D ex vivo patient-derived breast cancer model and patient biopsy for personalized therapy [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO5-14-06.

Prevalence and effect of PIK3CA H1047R somatic mutation among Indian head and neck cancer patients

PIK3CA is one among the several mutated genes in cancer, including head and neck squamous cell carcinoma (HNSCC). H1047R is a hotspot somatic mutation in PIK3CA that occurs most frequently in several forms of cancers. Distribution of PIK3CA H1047R mutation in Indian HNSCC patients was screened and its effect on disease progression and response to treatment was analysed in this study. Genomic DNA was extracted from tumour biopsies of HNSCC patients (n = 48) and polymerase chain reaction coupled restriction fragment length polymorphism (PCR-RFLP) technique was used to screen for the mutation. Overall survival (OS) and Progression-free survival (PFS) of the patients were calculated in order to study effect of this mutation on survival and response to treatment respectively. Results showed that irrespective of patients’ criteria, twenty-five patients (52 %) carried a heterozygous form of mutation (His/Arg) and the rest (48 %) were wild type (His/His). The mean OS of the cohort with the mutation was 20.451 months (SE ± 1.710 months) while 26.31 months (SE ± 2.431) was in wild type population. PFS of the patients with the mutation was 18.612 months (SE ± 2.072), and for the wild type population, it was 26.31 months (SE ± 2.431). These observations suggest that Indian HNSCC patients with PIK3CA H1047R mutation have poor prognosis.

Correlation of IDH1 gene expression error in breast tumor biopsy in patients with invasive ductal carcinoma.

One of the most important cancers in terms of worldwide prevalence is breast tumors, which have been less investigated in correlation with the enzyme Isocitrate Dehydrogenase 1 (IDH1) gene. The aim of this study was that expression of this gene could have significant effects on the progression of metastasis and invasive disease in breast cancer patients. We used the molecular method of RT-PCR with SYBR-Green to analyze breast tumor tissue from patients with metastasis and non-metastasis, the latter confirmed by the pathology department of Shohada-e Tajrish Hospital (serving as a control group). Also, patients population and its relationship with the degree of tumor in the IDH1 gene was investigated. The IDH1 gene has shown high expression in patients with metastatic breast cancer rather than in patients with non-metastatic breast cancer. The metastatic samples were compared with non-metastatic samples for IDH1 mRNA expression. In this research work, 72.5% (29 samples) were up-regulated in comparison to 27.5% of samples (11 samples) that did not exhibit high expression (P=0.000). This study examined the IDH1 gene expression, suggesting that changes in this gene's expression could impact the prognosis of breast cancer. However, further research is needed to draw definitive conclusions.

Prognostic value of p14ARF expression in diffuse large B cell lymphoma

The p14ARF-Hdm2-p53 signaling pathway targets tumor growth suppression, inhibits clonal proliferation, and maintains genome stability. It is inactivated in most human malignancies. The p14ARF protein is one of the main participants in the cascade. The aim of the study was to determine the prognostic value of the number of p14ARF-expressing tumor cells in biopsies of patients with diffuse large B cell lymphoma (DLBCL). Material and methods. The formalin-fixed paraffin embedded samples of tumor tissue of 104 patients with newly diagnosed DLBCL were included to the study. The relative number of cells expressing p14ARF was determined by immunohistochemical and morphometric methods. Differences in the content of p14ARF-positive tumor cells between groups of patients divided according to clinical and laboratory parameters were determined using the Mann–Whitney U test. Prediction of an unfavorable response to therapy was carried out using binary logistic regression with calculation of the odds ratio and 95 % confidence interval; variables were selected using Wald backward elimination method. The risk of an event occurring was calculated using Cox regression analysis. Results. The content of p14ARF-positive cells is higher in tumor biopsies of patients with high and high-intermediate risk according to the international prognostic index than in patients with low and lowintermediate risk. A relationship between an increase in the number of p14ARF-positive tumor cells, the absence of a complete response to first-line R-CHOP therapy, and an increased risk of death in patients with DLBCL has been established. Conclusions. The studied marker p14ARF can be used as an additional morphological predictor of the unfavorable course of DLBCL.

Cytosolic DNA sensor AIM2 promotes KRAS-driven lung cancer independent of inflammasomes.

Constitutively active KRAS mutations are among the major drivers of lung cancer, yet the identity of molecular co-operators of oncogenic KRAS in the lung remains ill-defined. The innate immune cytosolic DNA sensor and pattern recognition receptor (PRR) Absent-in-melanoma 2 (AIM2) is best known for its assembly of multiprotein inflammasome complexes and promoting an inflammatory response. Here, we define a role for AIM2, independent of inflammasomes, in KRAS-addicted lung adenocarcinoma (LAC). In genetically defined and experimentally induced (nicotine-derived nitrosamine ketone; NNK) LAC mouse models harboring the KrasG12D driver mutation, AIM2 was highly upregulated compared with other cytosolic DNA sensors and inflammasome-associated PRRs. Genetic ablation of AIM2 in KrasG12D and NNK-induced LAC mouse models significantly reduced tumor growth, coincident with reduced cellular proliferation in the lung. Bone marrow chimeras suggest a requirement for AIM2 in KrasG12D-driven LAC in both hematopoietic (immune) and non-hematopoietic (epithelial) cellular compartments, which is supported by upregulated AIM2 expression in immune and epithelial cells of mutant KRAS lung tissues. Notably, protection against LAC in AIM2-deficient mice is associated with unaltered protein levels of mature Caspase-1 and IL-1β inflammasome effectors. Moreover, genetic ablation of the key inflammasome adapter, ASC, did not suppress KrasG12D-driven LAC. In support of these invivo findings, AIM2, but not mature Caspase-1, was upregulated in human LAC patient tumor biopsies. Collectively, our findings reveal that endogenous AIM2 plays a tumor-promoting role, independent of inflammasomes, in mutant KRAS-addicted LAC, and suggest innate immune DNA sensing may provide an avenue to explore new therapeutic strategies in lung cancer.

Abstract 177: Targeting murine or human KLRG1 exerts potent anti-tumor efficacy involving both CD8T cells and NK cells

Abstract Clinical response to anti-PD-1 immunotherapy is correlated with patients who have a T cell-inflamed tumor microenvironment. Some patients with immune cell infiltration fail to respond, and some patients experiencing an initial clinical response develop acquired resistance. It is likely that additional immune-regulatory pathways need to be targeted to expand the efficacy of immunotherapies. To identify a broader array of therapeutic relevant immunotherapy molecules in T cell-inflamed tumors, our lab utilized gene expression profiling to characterize tumor antigen-specific dysfunctional CD8+ T cells in the tumor microenvironment. One molecule that was found to be overexpressed on these CD8+ T cells was C-type lectin inhibitory receptor, KLRG1. KLRG1 is an ITIM domain-containing receptor mostly explored on NK cells, and the known ligands are N- and E- cadherins which are broadly expressed in solid cancers. Analysis of single cell RNA-Seq data from tumor biopsies of melanoma patients classified as responders or non-responders to anti-PD-1 therapy revealed significantly higher expression of KLRG1 expression on tumor-infiltrating T cell subsets in non-responders, suggesting a possible salvage immune suppressive role. To determine the potential functional relevance of KLRG1 on tumor control, we generated KLRG1 knockout (KO) mice, then implanted tumors and assessed tumor growth rate in vivo. KLRG1 KO mice showed markedly slowed B16 melanoma tumor growth compared to WT mice, arguing it is a critical negative regulator of anti-tumor immunity. Both antigen-specific CD8+ T cells and NK cells were expanded in these tumors, and depletion of CD8+ T cells or NK cells eliminated this tumor control. Genetic deletion of N-cadherin from B16 cells also resulted in slowed tumor growth, suggesting that tumor cells are providing the functionally relevant ligand. To assess the degree of inhibitory function of human KLRG1, we generated a humanized KLRG1 knock-in mouse model. We confirmed that human KLRG1 can biochemically interact with murine cadherins. Knock-in mice with the humanized KLRG1 protein had significantly increased tumor growth compared to both WT and KLRG1 KO mice, indicating a stronger immunosuppressive effect of human KLRG1 compared to murine KLRG1. An antagonistic antibody blocking interaction of human KLRG1 with its ligands was generated, which potentiated human T cell activation in vitro. Administration of anti-human KLRG1 Ab to tumor-bearing humanized KLRG1 mice led to markedly reduced tumor growth. In summary, our data support KLRG1 as a functionally critical negative regulator of the anti-tumor immune response and that blocking KLRG1-cadherin interactions has potential as a therapeutic candidate. Citation Format: Tyler A. Jones, Stephen Sinicrope, Kei Yasuda, Jan Pinkas, Thomas F. Gajewski. Targeting murine or human KLRG1 exerts potent anti-tumor efficacy involving both CD8T cells and NK cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 177.

Abstract 7023: Application of exclusive liquid repellency for low input CUT&amp;Tag histone analyses in prostate cancer spheroids

Abstract Introduction/Background: Epigenetic alterations, including histone modifications and DNA methylation, drive treatment resistance and lethal prostate cancer. However, epigenetic assays typically require thousands of cells and are difficult to scale for patient tumor biopsies. While identifying these alterations is possible in cell lines, these analytes are more difficult to follow in clinical settings. Patient-derived organoids have emerged as viable intermediaries to investigate the changing chromatin landscape during the progression toward treatment-emergent prostate cancer. This report seeks to adapt the Cleavage Under Targets and Tagmentation (CUT&amp;Tag) assay for use on a microfluidic technology to eliminate cell loss associated with complex, multi-step epigenetic assays to facilitate analysis of low input prostate cancer spheroids. Methods: The Oil Immersed Lossless Total Analysis System (OIL-TAS) is an exclusive liquid repellency (ELR) platform that passes magnetic bead-bound analytes through immiscible phases to separate and extract analytes of interest while eliminating traditional centrifugation and wash steps that lead to sample loss. This platform enables adaptation of complex molecular assays such as CUT&amp;Tag for lossless sample manipulation. We focus on the analysis of histone modifications in rare cells utilizing antibodies for H3K27 acetylation and methylation. Comparison of LNCaP prostate cancer cell lines harvested from either 2D cell culture or 3D spheroids was performed to evaluate the sensitivity and specificity of this integrated assay. Results: The macroscale CUT&amp;Tag assay has been performed with inputs of 25,000 nuclei from LNCaP spheroids with greater yields than similar inputs from 2D LNCaP cell culture. Yield increases have also been seen when performing the assay with inputs &amp;lt;10,000 nuclei in microscale on the OIL-TAS relative to the macroscale. Utilizing the OIL-TAS platform with spheroid inputs will allow for more sensitive investigation of histone modifications. Conclusions: Integration of 3D, humanized models of tumor growth into the CUT&amp;Tag assay will enable discovery of differential epigenetic regulation within patient-derived organoids or complex co-culture studies. Establishing baseline epigenetic landscapes among these intermediary models will enable a new platform for drug testing. Utilization of the OIL-TAS platform will allow for miniaturization of the assay down to 1,000 cell inputs and enable multiparametric RNA-seq, EM-seq, and CUT&amp;Tag-seq of the same patient samples for longitudinal study. Citation Format: Zachary J. Kauffman, Kevin Koesser, Kyle T. Helzer, Jamie M. Sperger, Marina N. Sharifi, Chao Li, Erika Heninger, Xavier Hazelberg, Cole Gilsdorf, Shuang G. Zhao, Duane S. Juang, David J. Beebe, Joshua M. Lang. Application of exclusive liquid repellency for low input CUT&amp;Tag histone analyses in prostate cancer spheroids [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 7023.

Molecular assessment of intratumoral immune cell subsets and potential mechanisms of resistance to odronextamab, a CD20×CD3 bispecific antibody, in patients with relapsed/refractory B-cell non-Hodgkin lymphoma

BackgroundPatients with relapsed/refractory B-cell non-Hodgkin lymphoma (R/R B-NHL) have a significant need for effective treatment options. Odronextamab is an Fc-silenced, human, CD20×CD3 bispecific antibody that targets CD20-expressing cells via T-cell-mediated...

Radiotherapy induces an increase in serum antioxidant capacity reflecting tumor response

Background and purposeRadiotherapy (RT) is a mainstay component of treatment for patients with head and neck squamous cell carcinoma (HNSCC), but responses vary. As RT relies upon oxidative damage, antioxidant expression in response to RT-induced reactive oxygen species (ROS) could compromise treatment response. We aimed to examine local and systemic antioxidant responses to increased RT-induced ROS in relation to treatment success. Materials and methodsNuclear factor erythroid 2-related factor 2 (NRF2), the main antioxidant transcription factor, was immunofluorescently stained in FaDu cells and in tumor biopsies of patients with oral cavity/oropharynx HNSCC before and after five fractions of RT. Besides, total antioxidant capacity (TAC) was analyzed in HNSCC tumor cells in vitro and in serum of HNSCC patients before, during, and after RT. ResultsData revealed an increase in NRF2 expression and TAC in head and neck cancer cells in vitro over the course of 5 daily fractions of 2 Gy. In accordance, also in patients’ tumors NRF2 expression increased, which was associated with increased serum TAC during RT. Increasing serum TAC was related to impaired local tumor control. ConclusionRadiation induced NRF2 expression and upregulated TAC, which may compromise the effect of RT-induced ROS. Changes in serum TAC during RT could serve as a novel predictor of treatment outcome in HNSCC patients.Medical Ethics Review Committee (CMO) approval – CMO number: 2007/104.

Digitally assessed lymphocyte infiltration in rectal cancer biopsies is associated with pathological response to neoadjuvant therapy

A frequently used treatment strategy in locally advanced rectal cancer (RC) is neoadjuvant therapy followed by surgery. Patients treated with neoadjuvant therapy achieve varying pathological response, and currently, predicting the degree of response is challenging. This study examined the association between digitally assessed histopathological features in the diagnostic biopsies and pathological response to neoadjuvant therapy, aiming to find potential predictive biomarkers. 50 patients with RC treated with neoadjuvant chemotherapy and/or radiotherapy followed by surgery were included. Deep learning-based digital algorithms were used to assess the epithelium tumor area percentage (ETP) based on H&E-stained slides, and to quantify the density of CD3+ and CD8+ lymphocytes, as well as the CD8+/CD3+ lymphocyte percentage, based on immunohistochemically stained slides, from the diagnostic tumor biopsies. Pathological response was assessed according to the Mandard method. A good pathological response was defined as tumor regression grade (TRG) 1–2, and a complete pathological response was defined as Mandard TRG 1. Associations between the ETP and lymphocyte densities in the diagnostic biopsies and the pathological response were examined. The density of CD8+ lymphocytes, and the CD8+/CD3+ lymphocyte percentage, were associated with both good and complete response to neoadjuvant therapy, while the density of CD3+ lymphocytes was associated with complete response. The ETP did not correlate with response to neoadjuvant therapy. It is well-known that infiltration of lymphocytes in colorectal cancer is a prognostic biomarker. However, assessment of CD8+ and CD3+ lymphocytes in the diagnostic tumor biopsies of patients with RC may also be useful in predicting response to neoadjuvant therapy.

Modulation of the Btla-HVEM Axis to Enhance CAR T Cell Immunotherapy Against Cancer

Introduction: The efficacy of adoptive T cell immunotherapies against cancer, such as chimeric antigen receptor (CAR) T cells, is severely blunted by the immunosuppressive tumor microenvironment (TME). We sought to investigate the role of the TME in cancer resistance to effector T cells in order to define actionable targets to enhance CAR T cell immunotherapies. We initially used Hodgkin lymphoma (HL) as an ideal tumor model since it is characterized by a TME that is profoundly infiltrated by immunosuppressive cells, and then we expanded our findings to multiple cancer models. We first sought to identify the dominant interactions of immunosuppressive cellular compartments and effector T cells by analyzing single-cell RNA sequencing data on a total of 26 (4 exploratory + 22 validation) HL patient tumor biopsies. Using the CellPhoneDB algorithm, we inferred that the ligand B- and T-lymphocyte attenuator (BTLA) on effector T cells and the receptor Herpesvirus entry mediator (HVEM, TNFRSF14) on immunosuppressive cells (e.g., regulatory T cells, monocytes) strongly interact in the TME and promote T cell dysfunction ( Fig 1a). Akin to the canonical checkpoint PD1, BTLA recruits two potent tyrosine phosphatases, SHP-1 and SHP-2, to disable early T cell activation. Thus, we rationalized that BTLA expression on T cells might reduce their anti-tumor function. We hypothesized that deleting BTLA in CAR T cells would abolish BTLA-HVEM trans interactions at the immunological synapse and unleash the cytotoxic potential of CAR T cells. Methods and Results: We first generated BTLA KO anti-CD30 CAR T (CART30) cells against HL. To test their function in vivo, 15x10 6 HDLM-2 (CD30+HVEM+ HL) cells were subcutaneously implanted into NSG mice on day 0, and on day 62, 3x10 5 CAR30+ T cells were infused intravenously. Our results demonstrated that BTLA KO significantly enhances the function of anti-CD30 CAR T cells in HVEM+ HL ( Fig 1b), as assessed via tumor size (caliper) and CART30 expansion in the peripheral blood (flow cytometry). Additionally, we generated BTLA KO 4-1BBζ CART19 cells, which showed greater in vivo anti-tumor function in a subcutaneous tumor model of DLBCL (CD19+ HVEM+ OCI-Ly18). Serum collected from OCI-Ly18-bearing NSG mice infused with BTLA KO CART19 was enriched in effector cytokines (e.g., TNF, IFNγ, IL-2) as measured by Luminex. We then extended these findings into HVEM+ solid tumor models. BTLA KO improved tumor control in vitro in short-term killing experiments (Incucyte SX5) for both CAR and TCR T cells, respectively directed against prostate cancer (HER2+ PC-3) and melanoma (GP-100+ DM-6). Importantly, we demonstrated that BTLA KO in primary BALB/c-derived murine CAR T cells enhances tumor control in A20 murine lymphoma. In this model, BTLA KO tumor-infiltrating CAR T cells showed substantially reduced exhaustion in the TME relative to wild-type CAR T cells. Mechanistically, we showed that targeted mutations in BTLA intracellular tyrosine motifs effectively reduce the recruitment of SHP-1/2 and preserve the docking domain of the pro-stimulatory Grb2, thus maintaining high NFAT signaling and increased persistence in vivo. These effects were dependent on the expression of HVEM on tumor cells. Finally, we found that high BTLA RNA expression in tisagenlecleucel infusion products correlates with poor response to treatment in patients with DLBCL and FL (NCT02030834). Conclusion: Our results reveal a critical role of the BTLA-HVEM axis in inhibiting CAR T cell function, and demonstrate that CRISPR-Cas9 deletion of BTLA leads to enhanced anti-tumor efficacy in multiple models of cancer. The key mechanism is the reduction of SHP-1/2 recruitment and the consequent increase in CAR T cell activation. The results of this study will be translated into a first in human clinical trial of BTLA-deficient CAR T cells for relapsed or refractory cancer.

Detection of Tumor DNA in Bronchoscopic Fluids in Peripheral NSCLC: A Proof-of-Concept Study

IntroductionDNA genotyping from plasma is a useful tool for molecular characterization of NSCLC. Nevertheless, the false-negative rate justifies the development of methods with higher sensitivity, especially in difficult-to-reach peripheral lung tumors. MethodsWe aimed at comparing molecular analysis from the supernatant of guide sheath flush fluid collected during radial-EndoBronchial UltraSound (r-EBUS) bronchoscopy with plasma sampling and tumor biopsies in patients with peripheral NSCLC. The DNA was genotyped using high-throughput sequencing or the COBAS mutation test. There were 65 patients with peripheral lung tumors subjected to concomitant sampling of guide sheath flush supernatant, plasma tumor DNA, and tumor biopsy and cytology using r-EBUS. There were 33 patients (including 24 newly diagnosed with having NSCLC) with an identifiable tumor mutation in the primary lesion selected for the comparative analysis. ResultsGuide sheath flush-based genotyping yielded a mutation detection rate of 61.8% (17 of 24 mutated EGFR, one of two ERBB2, one of one KRAS, one of one MAP2K, one of four MET, and zero of one STK11), compared with 33% in plasma-based genotyping (p = 0.0151). Furthermore, in eight of 34 r-EBUS without tumor cells on microscopic examination, we were able to detect the mutation in four paired guide sheath flush supernatant, compared with only two in paired plasma. ConclusionThe detection of tumor DNA in the supernatant of guide sheath flush fluid collected during r-EBUS bronchoscopy represents a sensitive and complementary method for genotyping NSCLC.

Abstract PO-095: TGF-β carrying exosomes in plasma of HNSCC as potential biomarkers of disease progression in patients with HNSCC

Abstract Background: The contribution of TGFβ+ exosomes, now referred to as small extracellular vesicles (sEV), in plasma of cancer patients to disease progression has been unclear. Levels of TGFβ in plasma often do not correlate with clinicopathological data, and TGFβ can exert dual (yin-yang) effects as a tumor promoter and a tumor inhibitor. We evaluated the potential of tumor-derived sEV dubbed TEX to serve as liquid tumor biopsy in patients with HNSCC. Methods: Plasma was obtained from 3 different cohorts of patients with HNSCC (n=97) and HDs (n=22). Clinicopathology/demographic data were available for all patients. sEV were isolated by ultrafiltration/size exclusion chromatography (SEC) from plasma or cell supernatants. TGF-β levels in plasma were assessed by ELISA; TGF-β expression in tissues was studied by IHC and immunoblots; immunoblots, flow cytometry and LC-MS/MS were used to measure TGF-β in isolated sEV. TGFB1 gene expression was analyzed using the TCGA Head and Neck Cancer database (n=520 cases and 44 NC). TGF-β signaling and activity of EVs were quantified in the reporter cell (MFB-F11) proliferation assays. Changes of TGF-β expression levels in plasma, tissues and sEV during carcinogenesis were studied in an orthotopic 4NQO mouse model. Results: Using the TCGA we found high expression levels of the vesiculation genes regulating EV production/release and of the TGFB1 gene expression in HNSCC. In the 4NQO orthotopic model of OSCC, cancer progression correlated with TGF-β accumulations in tumor tissues and a significant increase in circulating TGF-β+ sEV. In HNSCC patients, TGF-β levels and activity in plasma and TGF-β expression levels in tumor tissues were significantly elevated relative to controls but did not correlate with clinicopathologic data, tumor burden or disease outcome. TEX produced by HNSCC cell lines carried TGF-β and initiated Smad3 signaling in reporter cells. TGF-β inhibitors blocked this signaling. High TGFβ abundance in sEV was confirmed by proteomics and by RNAseq using the TCGA data base. Levels of TGF-β expression in sEV, sEV numbers and TGF-β activity of sEV were significantly elevated in HNSCC patients vs HDs’ sEV and correlated with tumor stage and LN involvement. Conclusions: TEX and sEV from HNSCC patients’ plasma carry TGF-β which reflects disease progression in HNSCC patients and in a mouse model of oral carcinogenesis. Neither plasma levels of TGF-β (ELISA) nor levels of TGF-β expression in the tumor (IHC) correlated with disease progression. Only sEV-associated TGF-β correlates with tumor burden and shows promise as a non-invasive biomarker of HNSCC progression and response to therapy. Citation Format: Nils Ludwig, Saigopalakrishna S. Yerneni, Theresa L. Whiteside. TGF-β carrying exosomes in plasma of HNSCC as potential biomarkers of disease progression in patients with HNSCC [abstract]. In: Proceedings of the AACR-AHNS Head and Neck Cancer Conference: Innovating through Basic, Clinical, and Translational Research; 2023 Jul 7-8; Montreal, QC, Canada. Philadelphia (PA): AACR; Clin Cancer Res 2023;29(18_Suppl):Abstract nr PO-095.

Considerations on surgical strategies and associated risk profiles for endoscopic tumor biopsies within the third ventricle and periaqueductal region

IntroductionNeuroendoscopic techniques have proven to be a successful and minimally-invasive technique for tumor biopsies within the third ventricle in pediatric patients. However, a comprehensive assessment of associated surgical strategies, techniques, and morbidity is essential to optimize patient outcomes.MethodsThis retrospective study analyzed full endoscopic tumor biopsies in pediatric patients with tumors in the third ventricle and periaqueductal region. Data from 1995 to 2022 were collected from medical records, imaging, and intraoperative video documentation.ResultsIn this study, 16 shear endoscopic tumor biopsies were performed using the transventricular transforaminal approach. Tumors were located in the anterior or mid part of the third ventricle (50%) or in the periaqueductal and pineal recess region (50%). Preoperative hydrocephalus was seen in 81.25%. Tumor biopsies were harvested successfully in all cases. Simultaneous ETV was performed in 12 (75%) cases and additional septostomy in 3 (18.75%). Significant intraoperative bleeding occurred in 3 cases (18.75%). All bleeding situations could be successfully managed with continuous irrigation. Histopathology revealed astrocytoma as the predominant diagnosis (75%). No new neurologic deficits were observed, except for one case of transient oculomotor nerve paralysis after ETV. Hydrocephalus persisted in 18.6% of all cases with the need of urgent ventriculoperitoneal shunting in two patients.ConclusionIn conclusion, neuroendoscopy emerges as an effective technique for tumor biopsies within the third ventricle in pediatric patients, offering the added advantage of simultaneous treatment of obstructive hydrocephalus. However, it is essential to acknowledge the specific intra- and postoperative risks associated with various surgical strategies. The safe management and achievement of favorable clinical results demand extensive experience and expertise.

SAMHD1 expression is a surrogate marker of immune infiltration and determines prognosis after neoadjuvant chemotherapy in early breast cancer.

The lack of validated surrogate biomarkers is still an unmet clinical need in the management of early breast cancer cases that do not achieve complete pathological response after neoadjuvant chemotherapy (NACT). Here, we describe and validate the use of SAMHD1 expression as a prognostic biomarker in residual disease in vivo and in vitro. SAMHD1 expression was evaluated in a clinical cohort of early breast cancer patients with stage II-III treated with NACT. Heterotypic 3D cultures including tumor and immune cells were used to investigate the molecular mechanisms responsible of SAMHD1 depletion through whole transcriptomic profiling, immune infiltration capacity and subsequent delineation of dysregulated immune signaling pathways. SAMHD1 expression was associated to increased risk of recurrence and higher Ki67 levels in post-NACT tumor biopsies of breast cancer patients with residual disease. Survival analysis showed that SAMHD1-expressing tumors presented shorter time-to-progression and overall survival than SAMHD1 negative cases, suggesting that SAMHD1 expression is a relevant prognostic factor in breast cancer. Whole-transcriptomic profiling of SAMHD1-depleted tumors identified downregulation of IL-12 signaling pathway as the molecular mechanism determining breast cancer prognosis. The reduced interleukin signaling upon SAMHD1 depletion induced changes in immune cell infiltration capacity in 3D heterotypic in vitro culture models, confirming the role of the SAMHD1 as a regulator of breast cancer prognosis through the induction of changes in immune response and tumor microenvironment. SAMHD1 expression is a novel prognostic biomarker in early breast cancer that impacts immune-mediated signaling and differentially regulates inflammatory intra-tumoral response.

The minimally invasive transventricular endoscopic approach to third ventricular lesions in pediatric patients—all-rounder with limitations?

IntroductionThe surgical management of third ventricular lesions poses unique challenges, requiring careful consideration of various approaches and techniques. This study focuses on the transventricular transforaminal endoscopic approach and aims to provide insights into its indications, limitations, technical nuances, and potential complications in pediatric patients.MethodsA retrospective analysis was conducted using data from a 13-year period on pediatric patients who were subjected to transforaminal endoscopic surgery for third ventricular lesions. The study utilized a prospectively maintained internal database, extracting demographic data, preoperative assessment, surgical details, and postoperative follow-up information. The surgical technique is presented in detail, and exemplary case reports highlight relevant surgical considerations.ResultsOut of 578 endoscopic transforaminal procedures, 24 surgeries were performed on pediatric patients with third ventricular lesions. Performed procedures consisted of cyst resection (13 cases), solid tumor resection (4 cases), and tumor biopsies with CSF pathway restoration (7 cases). The mean age at the time of surgery was 7.6 years. Postoperatively, 14 patients showed transient nausea and vomiting (58.3%); 10 patients showed pneumocephalus on postoperative MRI (41.7%). No emergency postoperative re-interventions nor perioperative mortality were observed.ConclusionThe endoscopic transventricular transforaminal approach is a safe approach for lesion resection, CSF pathway restoration, and tumor biopsy in pediatric patients with third ventricle lesions. The author’s results support the use of this minimally invasive technique as an alternative to more extensive approaches, particularly to the interforniceal interhemispheric approach. However, surgical success is highly dependent to the individual surgeon’s experience and moreover to a suitable indication setting. Careful preoperative planning and knowledge of the approaches’ pro and cons is mandatory for successful application of this approach.