Natural Killer and T Cell Infiltration in Canine Osteosarcoma: Clinical Implications and Translational Relevance

Metastatic osteosarcoma has a bleak prognosis in both humans and dogs, and there have been minimal therapeutic advances in recent decades to improve outcomes. Naturally occurring osteosarcoma in dogs is shown to be a highly suitable model for human osteosarcoma, and limited data suggest the similarities between species extend into immune responses to cancer. Studies show that immune infiltrates in canine osteosarcoma resemble those of human osteosarcoma, and the analysis of tumor immune constituents as predictors of therapeutic response is a promising direction for future research. Additionally, clinical studies in dogs have piloted the use of NK transfer to treat osteosarcoma and can serve as valuable precursors to clinical trials in humans. Cytotoxic lymphocytes in dogs and humans with osteosarcoma have increased activation and exhaustion markers within tumors compared with blood. Accordingly, NK and T cells have complex interactions among cancer cells and other immune cells, which can lead to changes in pathways that work both for and against the tumor. Studies focused on NK and T cell interactions within the tumor microenvironment can open the door to targeted therapies, such as checkpoint inhibitors. Specifically, PD-1/PD-L1 checkpoint expression is conserved across tumors in both species, but further characterization of PD-L1 in canine osteosarcoma is needed to assess its prognostic significance compared with humans. Ultimately, a comparative understanding of T and NK cells in the osteosarcoma tumor microenvironment in both dogs and humans can be a platform for translational studies that improve outcomes in both dogs and humans with this frequently aggressive disease.

OXPHOS Promotes Apoptotic Resistance and Persistence in TH17 cells

Apoptotic cell death is a cell-intrinsic, immune tolerance mechanism that regulates the magnitude and resolution of T cell-mediated responses. Evasion of apoptosis is critical for the generation of memory T cells, as well as autoimmune T cells, and knowledge of the mechanisms that enable resistance to apoptosis will provide insight into ways to modulate their activity during protective and pathogenic responses. IL-17-producing CD4 T cells (TH17s) are long-lived, memory cells. These features enable their role in host defense, chronic inflammatory disorders, and anti-tumor immunity. A growing number of reports now indicate that TH17s in vivo require mitochondrial oxidative phosphorylation (OXPHOS), a metabolic phenotype that is poorly induced in vitro. To elucidate the role of OXPHOS in TH17 processes, we developed a system to polarize TH17s that metabolically resembled their in vivo counterparts. We discovered that directing TH17s to use OXPHOS promotes mitochondrial fitness, glutamine anaplerosis, and an anti-apoptotic phenotype marked by high BCL-XL and low BIM. Through competitive co-transfer experiments and tumor studies, we further revealed how OXPHOS protects TH17s from cell death while enhancing their persistence in the periphery and tumor microenvironment. Together, our work demonstrates a non-classical role of metabolism in regulating TH17 cell fate and highlights the potential for therapies that target OXPHOS in TH17-driven diseases.

Frequency of Neuroendocrine Tumor Studies: Using Latent Dirichlet Allocation and HJ-Biplot Statistical Methods

Background: Neuroendocrine tumors (NETs) are severe and relatively rare and may affect any organ of the human body. The prevalence of NETs has increased in recent years; however, there seem to be more data on particular types, even though, despite the efforts of different guidelines, there is no consensus on how to identify different types of NETs. In this review, we investigated the countries that published the most articles about NETs, the most frequent organs affected, and the most common related topics. Methods: This work used the Latent Dirichlet Allocation (LDA) method to identify and interpret scientific information in relation to the categories in a set of documents. The HJ-Biplot method was also used to determine the relationship between the analyzed topics, by taking into consideration the years under study. Results: In this study, a literature review was conducted, from which a total of 7658 abstracts of scientific articles published between 1981 and 2020 were extracted. The United States, Germany, United Kingdom, France, and Italy published the majority of studies on NETs, of which pancreatic tumors were the most studied. The five most frequent topics were t_21 (clinical benefit), t_11 (pancreatic neuroendocrine tumors), t_13 (patients one year after treatment), t_17 (prognosis of survival before and after resection), and t_3 (markers for carcinomas). Finally, the results were put through a two-way multivariate analysis (HJ-Biplot), which generated a new interpretation: we grouped topics by year and discovered which NETs were the most relevant for which years. Conclusions: The most frequent topics found in our review highlighted the severity of NETs: patients have a poor prognosis of survival and a high probability of tumor recurrence.

Impact of the First Generation of Children’s Oncology Group Clinical Trials on Clinical Practice for Wilms Tumor

Refinements in surgery, radiation therapy, and chemotherapy since the mid-20th century have resulted in a survival rate exceeding 90% for patients with Wilms tumor (WT). Although this figure is remarkable, a significant proportion of patients continue to have event-free survival (EFS) estimates of <75%, and nearly 25% of survivors experience severe chronic medical conditions. The first-generation Children’s Oncology Group (COG) renal tumor trials (AREN ‘0’), which opened to enrollment in 2006, focused on augmenting treatment regimens for WT subgroups with predicted EFS <75% to 80%, including those with the adverse prognostic marker of combined loss of heterozygosity (LOH) at chromosomes 1p/16q, pulmonary metastasis with incomplete lung nodule response after 6 weeks of chemotherapy, bilateral disease, and anaplastic histology. Conversely, therapy was reduced for patient subgroups with good outcomes and potential for long-term toxicity, such as those with lung metastasis with complete lung nodule response after 6 weeks of chemotherapy. This article summarizes the key findings of the first-generation COG renal tumor studies and their implications for clinical practice.

Diagnostic possibilities and limitations of urgent intraoperative pathologicanatomical studies in oncogynecology

Introduction. One of the variants of intravital pathological and anatomical diagnostics is intraoperative pathological and anatomical ("urgent") examination, which serves for tumor process verification. Urgent intraoperative pathological and anatomical examination is widely used when there are certain differential diagnostic difficulties and limitations of instrumental methods of examination.The purpose of the study — to analyze the possibilities, limitations and the accuracy of "urgent" pathologic and anatomical diagnostics in oncogynecological diseases. Materials and methods. We retrospectively analyzed medical records of 378 inpatients treated in the gynecologic oncology department of CHOKZO and NM for the period from January 2016 to January 2021. Results and discussion. Urgent histological examination was used to diagnose ovarian tumors (82%, n=310); to evaluate the extent of a tumor process in uterine body cancer, ovarian cancer, cervical cancer (peritoneal carcinomatosis, ingrowth into adjacent tissues and organs) (15%, n=57); less often to evaluate resection margin ablation in cervical cancer, uterine body cancer (3%, n=11). In a comparison of conclusions after urgent morphological examination and conduction of material, discrepancies were registered only in hypodiagnostic ovarian tumors (in 5.8% of all "urgent" ovarian tumor studies, n=18), when the question about the malignancy potential of a process cannot be reliably decided. The reliability of intraoperative morphological verification of the process is 94.2%. The sensitivity is 96%, specificity is 97%, which is consistent with the results of other studies. Conclusions. Intraoperative morphological diagnosis is a highly specific and highly sensitive method of investigation. There are limitations of this diagnostic method depending on the volume of tissue material, quality of cryostat sections, as well as tumor features (e.g., ovarian masses) consisting of heterologous morphological areas. A compliant, multidisciplinary approach is required to successfully meet the challenges of intraoperative examination.

EPCT-20. TECHNICAL FEASIBILITY SODIUM (23NA) MRI OF PEDIATRIC GLIOMAS

Pediatric glioma response to novel targeted therapy can be heterogeneous on conventional proton (1H) MRI. Sodium concentration, as measured with 23Na MRI in adult brain tumors can provide complementary assessment of tumor proliferation to conventional MRI. However, 23Na MRI pediatric brain tumor studies are lacking. Determine the technical feasibility of performing sodium23Na MRI on pediatric glioma patients. Prospective study of an immunotherapy trial for newly diagnosed and recurrent gliomas (high-grade gliomas, low-grade gliomas, brainstem gliomas) in which participants were imaged with 23Na MRI at 3.0 Tesla. The participants (n=26, 14 males) with median age of 11 years (range = 4–23 years of age) were prospectively evaluated with sodium. 23Na MRI is technically feasible in the pediatric population and can distinguish different types of pediatric gliomas at baseline.

EMBR-15. PRC2 COMPLEX ENFORCES NEURONAL LINEAGE AND SUPPRESSES TUMOR GROWTH IN SHH MEDULLOBLASTOMA

Hyperactivation of Sonic Hedgehog (SHH) signaling pathway drives tumor progression in the largest medulloblastoma subgroup. During cerebellar development, promoters of SHH target genes show inhibitory trimethylation of histone H3 at lysine 27 (H3K27me3), mediated by the Polycomb Repressive Complex 2 (PRC2). Here, we explored the regulation of cerebellar growth and medulloblastoma tumorigenesis by PRC2 complex components EED and EZH2. For developmental studies, we conditionally deleted Eed or Ezh2 in the Atoh1 lineage that gives rise to the cerebellar granule neuron progenitors (CGNP) that are cells of origin for SHH medulloblastomas. For tumor studies, we bred the conditional Eed- or Ezh2-deleted mouse lines with mice genetically engineered to develop SHH medulloblastoma. Our developmental studies showed that Eed was absolutely required for cerebellar growth. Eed-deleted CGNPs underwent aberrant, myocyte-like differentiation and spontaneous apoptosis, resulting in cerebellar hypoplasia. In contrast, Ezh2 deletion produced no developmental phenotype, despite blocking all H3K27me3 in CGNPs. Our tumor studies showed that Eed-deleted medulloblastomas similarly showed aberrant, myocyte differentiation, but unlike CGNPs, did not undergo widespread apoptosis. Eed-deleted medulloblastomas progressed more rapidly than control tumors, indicating that the inappropriate, muscle-like differentiation did not slow tumor growth. Ezh2-deleted medulloblastomas similarly progressed more rapidly than controls. Our data show that the PRC2 complex acts to enforce neuronal lineage commitment in both development and tumorigenesis and to restrain tumor growth in SHH medulloblastoma. Myocyte differentiation in Eed-deleted tumors suggests that PRC2 loss of function may contribute to the medullomyoblastomas that have been observed in patients. The differences in developmental phenotype show that EZH2 and EED functions are non-identical and can be dissociated, while similar increase in tumor progression show tumor suppressive functions for both EED and EZH2.

RLIP Depletion Induces Apoptosis Associated with Inhibition of JAK2/STAT3 Signaling in Melanoma Cells

The incidence of malignant melanoma, a neoplasm of melanocytic cells, is increasing rapidly. The lymph nodes are often the first site of metastasis and can herald systemic dissemination, which is almost uniformly fatal. RLIP, a multi-specific ATP-dependent transporter that is over-expressed in several types of cancers, plays a central role in cancer cell resistance to radiation and chemotherapy. RLIP appears to be necessary for cancer cell survival because both in-vitro cell culture and in-vivo animal tumor studies show that the depletion or inhibition of RLIP causes selective toxicity to malignant cells. RLIP depletion/inhibition triggers apoptosis in cancer cells by inducing the accumulation of endogenously formed glutathione-conjugates. In our in-vivo studies, we administered RLIP antibodies or antisense oligonucleotides to mice bearing subcutaneous xenografts of SKMEL2 and SKMEL5 melanoma cells and demonstrated that both treatments caused significant xenograft regression with no apparent toxic effects. Anti-RLIP antibodies and antisense, which respectively inhibit RLIP-mediated transport and deplete RLIP expression, showed similar tumor regressing activities, indicating that the inhibition of RLIP transport activity at the cell surface is sufficient to achieve anti-tumor activity. Furthermore, RLIP antisense treatment reduced levels of RLIP, pSTAT3, pJAK2, pSrc, Mcl-1, and Bcl2, as well as CDK4 and cyclin B1, and increased levels of Bax and pAMPK. These studies indicate that RLIP serves as a key effector in the survival of melanoma cells and is a valid target for cancer therapy. Overall, compounds that inhibit, deplete, or downregulate RLIP will function as wide-spectrum agents to treat melanoma, independent of common signaling pathway mutations.