Large Tumor Cells Research Articles

Polyploid cancer cells reveal signatures of chemotherapy resistance.

Therapeutic resistance in cancer significantly contributes to mortality, with many patients eventually experiencing recurrence after initial treatment responses. Recent studies have identified therapy-resistant large polyploid cancer cells in patient tissues, particularly in late-stage prostate cancer, linking them to advanced disease and relapse. Here, we analyzed bone marrow aspirates from 44 advanced prostate cancer patients and found the presence of circulating tumor cells with increased genomic content (CTC-IGC) was significantly associated with poorer progression-free survival. Single cell copy number profiling of CTC-IGC displayed clonal origins with typical CTCs, suggesting complete polyploidization. Induced polyploid cancer cells from PC3 and MDA-MB-231 cell lines treated with docetaxel or cisplatin were examined through single cell DNA sequencing, RNA sequencing, and protein immunofluorescence. Novel RNA and protein markers, including HOMER1, TNFRSF9, and LRP1, were identified as linked to chemotherapy resistance. These markers were also present in a subset of patient CTCs and are associated with recurrence in public gene expression data. This study highlights the prognostic significance of large polyploid tumor cells, their role in chemotherapy resistance, and the expression of markers tied to cancer relapse, offering new potential avenues for therapeutic development.

TMOD-11. ADVANCED MRI ANALYSIS TO ASSESS CHEMO-RADIATION RESPONSE IN PEDIATRIC EPENDYMOMA MODELS

Abstract Pediatric Ependymoma (EPN) is an aggressive brain tumor for which the benefits of chemo-radiation (CR) therapy have yet to be established. Our team has previously reported behavior patterns of EPN, including high tumor cellularity, cytological anaplasia, high mitotic index, tumor necrosis, and the presence of inflammatory cells such as M2-type macrophages. Recently, we have established advanced MRI protocols and computational algorithms for cell- and vessel-size imaging. The goal of this study is to develop advanced MRI analysis for CR response biomarkers (including tumor size, cell- and vessel-size correlates, and texture analysis) in mice with patient-derived xenografts (PDX) of pediatric EPN. Female severely immune deficient (SCID) mice were used for intracranial orthotopical inoculation of disaggregated tumors from pediatric EPN patients. All multi-parametric MRI sequences (fast spin echo, FLAIR, diffusion weighted, quantitative T2- and r2*-maps) were acquired on a Bruker 9.4 Tesla MRI scanner prior to CR, followed by 2 days and 2 weeks after CR treatment. All radiation treatment was performed using an animal image-guided precision XRAD irradiator (2Gyx5days), using MRI and CT guided EPN localization with added 30 mg/kg 5-fluoracil. All MRI analysis was performed using Bruker ParaVision software and MATLAB based modeling. The sensitivity of T2w-MRI scans was 0.2 mm for the smallest tumor detected; the median tumor volume at baseline was 2.5 mm3. Untreated mice showed rapid progression of tumor growth from small to intermediate to large EPN. The increased tumor sizes in untreated EPN were characterized by low ADC, highly elevated blood vessel density and large tumor cell size. A significant decrease in vessel size density and an increase in inflammatory cells were seen as soon as 2 days after CR therapy. The late response (2 weeks post CR) is characterized by increased ADC values and decreased cell size, resulting in significantly decreased tumor volumes.

SMARCA4-Deficient Undifferentiated Carcinoma of the Gastroesophageal Junction: A Case Report

Abstract Introduction/Objective To report a rare case of the newly characterized variant of gastric carcinoma; undifferentiated carcinoma with intact SMARCB1 (INI1) but lost SMARCA4/SMARCA2, and approach to diagnosis. Methods/Case Report A case of gastric mass extending to the gastroesophageal junction, microscopically, showing sheets of atypical, medium to large, discohesive, polygonal cells with large eccentric and pleomorphic nuclei, variably prominent nucleoli, and eosinophilic cytoplasm with brisk mitosis, in the background of marked necrosis and granulomatous inflammation. And having focally positive staining for cytokeratin and negative for melanoma, diffuse large B-cell lymphoma, high grade neuroendocrine tumor, sarcoma, rhabdoid/myoid-specific immunohistochemistry (IHC) markers. The case was further characterized with immunophenotypic, cytogenetic, and molecular findings. Results (if a Case Study enter NA) By immunohistochemistry (IHC), the large tumor cells were positive for vimentin, FLi-1 and patchy CD71. A subset of tumor cells showed CD34 positivity. The tumor cells were mainly negative (with rare focal positivity) for all cytokeratin including (CK AE1/AE3, EMA, and CK OSCAR). Tumor cells were negative for specific markers for melanoma, GIST, sarcomatous tumors, squamous cell carcinoma, hematolymphoid malignancies, and neuroendocrine tumors. EBER-ISH and HHV-8 were negative. The Ki67 showed a proliferative index of ~60%. The tumor cells demonstrated retention of INI1 (SMARCB1) with loss of both SMARCA2 and SMARCA4 by IHC. Molecular studies detected an inactivating mutation of the retinoblastoma-1 gene (RB1 I124Rfs*6) and TP53 with altered function compared to wild-type (TP53-G245S) with no mutations or deletion of SMARCB1 gene. The status of SMARCA4 gene came as indeterminate. No microsatellite Instability detected. Conclusion Our study demonstrates the challenge of diagnosing the SMARCA4/SMARCA1-deficient undifferentiating gastric carcinoma especially with negative cytokeratin stains, showing the immunohistochemistry profile of the tumor and its molecular findings in our case.

Polyploid cancer cells reveal signatures of chemotherapy resistance.

Therapeutic resistance in cancer significantly contributes to mortality, with many patients eventually experiencing recurrence after initial treatment responses. Recent studies have identified therapy-resistant large polyploid cancer cells in patient tissues, particularly in late-stage prostate cancer, linking them to advanced disease and relapse. Here, we analyzed bone marrow aspirates from 44 advanced prostate cancer patients and found the presence of CTC-IGC was significantly associated with poorer progression-free survival. Single cell copy number profiling of CTC-IGC displayed clonal origins with typical CTCs, suggesting complete polyploidization. Induced polyploid cancer cells from PC3 and MDA-MB-231 cell lines treated with docetaxel or cisplatin were examined through single cell DNA sequencing, RNA sequencing, and protein immunofluorescence. Novel RNA and protein markers, including HOMER1, TNFRSF9, and LRP1, were identified as linked to chemotherapy resistance. These markers were also present in a subset of patient CTCs and associated with recurrence in public gene expression data. This study highlights the prognostic significance of large polyploid tumor cells, their role in chemotherapy resistance, and their expression of markers tied to cancer relapse, offering new potential avenues for therapeutic development.

Polyploid cancer cells reveal signatures of chemotherapy resistance.

Therapeutic resistance in cancer significantly contributes to mortality, with many patients eventually experiencing recurrence after initial treatment responses. Recent studies have identified therapy-resistant large polyploid cancer cells in patient tissues, particularly in late-stage prostate cancer, linking them to advanced disease and relapse. Here, we analyzed bone marrow aspirates from 44 advanced prostate cancer patients and found the presence of circulating tumor cells with increased genomic content (CTC-IGC) was significantly associated with poorer progression-free survival. Single cell copy number profiling of CTC-IGC displayed clonal origins with typical CTCs, suggesting complete polyploidization. Induced polyploid cancer cells from PC3 and MDA-MB-231 cell lines treated with docetaxel or cisplatin were examined through single cell DNA sequencing, RNA sequencing, and protein immunofluorescence. Novel RNA and protein markers, including HOMER1, TNFRSF9, and LRP1, were identified as linked to chemotherapy resistance. These markers were also present in a subset of patient CTCs and associated with recurrence in public gene expression data. This study highlights the prognostic significance of large polyploid tumor cells, their role in chemotherapy resistance, and their expression of markers tied to cancer relapse, offering new potential avenues for therapeutic development.

Urothelial Carcinoma with Trophoblastic Differentiation-A Report with Review.

Urothelial carcinoma with trophoblastic differentiation is a rare type of urothelial carcinoma that poses a diagnostic challenge. A 50-year-old man presented with hematuria for 4 months duration. Ultrasonography examination showed polypoidal lesions along the right lateral wall and near the right vesicoureteric junction of the urinary bladder. The transurethral resection of the bladder tumor (TURBT) specimen showed marked necrosis and urothelial tumor cells arranged in nests, sheets, and papillae, admixed with multinucleated large cells. Deep muscle and extensive lymphovascular invasion were noted. The tumor cells were diffuse immunopositive for GATA3 and focal positive for p63 and SALL4. Large multinucleated tumor cells were immunopositive for β-hCG, GATA3, inhibin-α, and PLAP, focally positive for SALL4 while negative for p63. The patient denied further treatment and succumbed to the disease after 8 months of the TURBT procedure. We report a rare invasive urothelial carcinoma with trophoblastic differentiation and discuss the differential diagnosis and literature review.

Pseudosquamous Adenocarcinoma of the Lung: Clinicopathologic and Immunohistochemical Study of 10 Cases.

Pseudosquamous adenocarcinoma of the lung is an unusual morphologic variant of poorly differentiated non-small cell lung carcinoma that superficially resembles a squamous cell carcinoma. We have examined 10 cases of these tumors in 4 women and 6 men, aged 47 to 93 years. The tumors were all peripheral and measured from 1.5 to 5.5cm. All cases were characterized by solid nests of large polygonal tumor cells containing atypical nuclei with abundant cytoplasm and sharp cell borders, adopting a pavement-like architecture that simulated squamous cell carcinoma. Some cases demonstrated intracytoplasmic hyaline inclusions suggestive of keratinization. The nests of tumor cells often showed central comedo-like areas of necrosis. Intercellular bridges were not seen in any of the cases. The tumors often displayed marked clearing of the cytoplasm enhancing their epidermoid appearance. In 4 cases, the solid pseudosquamous areas were seen to merge with a focal lepidic adenocarcinoma component, and in 1 case, abortive microscopic foci of acinar differentiation were also noted within the tumor. One case showed focal sarcomatoid spindle cell areas. The tumor cells were negative for p40 and CK5/6 and labeled with TTF1 or Napsin-A, confirming an adenocarcinoma phenotype. Clinical follow-up information was available in 8 patients; 6 patients died of their tumors between 6 months to 11 years after diagnosis (mean: 3.1y). One patient died of complications related to surgery and one patient with a low-stage tumor died at 27 years from other causes. Solid pattern adenocarcinomas can be confused for squamous cell carcinoma and may require immunohistochemistry to determine their true phenotype.

Abstract 1991: Leiomyosarcoma poly-aneuploid cancer cells form in response to chemotherapy, contribute to chemoresistance, and lead to higher rates of metastatic recurrence

Abstract Poly-aneuploid cancer cells (PACCs) or as also known as “giant cells”, are a treatment resistant stem cell-like cancer phenotype. PACCs have been identified in numerous cancer types, and their presence appears to play a significant role in chemoresistance and poor patient outcomes. PACCs employ a multitude of polyploidization programs to enter this transient state in response to stress. After removal of stress, PACCs give rise to non-PACC progeny through potential mechanisms of neosis or depolyploidization that maintain chemotherapeutic resistance. Leiomyosarcoma (LMS) is a difficult to treat sarcoma that grows in smooth muscle that often develops chemoresistance. Here we report the first description of PACCs in LMS cell culture, LMS xenografts, and LMS patient tumor microarrays. LMS cells treated (doxorubicin, docetaxel, and gemcitabine) in vitro and in vivo lead to the development of mononucleated and multinucleated polypoid cells as the predominant phenotype via polyploidization. Polyploidization mechanisms identified included endocycling, endomitosis, and cell-cell fusion. In vitro, LMS PACCs had a significant increase in size and DNA content as well as an increase in resistance to chemotherapy as compared to parents. LMS PACCs also repopulated the culture with non-PACC LMS progeny cells. The PACC progeny cells maintained a significantly decreased (p<0.0001) response to chemotherapy compared to parent cells. PACCs were also identified in clinical samples from patients with LMS. Twenty-nine percent of samples (N=289) contained abnormally large tumor cells and fifty-eight percent contained abnormal nuclei. A positive correlation was observed in patient tumor samples between PACCs in metastatic tumors and recurrence (p=0.0277) and survival (p=0.0009) than those patient tumors without PACCs. The high rate of functional loss of TP53 in LMS (>90%) may contribute to the ability of PACCs to form abnormal, multiple nuclei. We therefore transfected LMS PACCs to express TP53 and observed an increased apoptotic response. Additionally, combining functional TP53 expression with low doses of doxorubicin increases the apoptotic response of LMS cells, potentially by targeting PACCs. LMS PACCs may contribute to the lack of response in patients with LMS. Identifying therapeutic approaches that prevent or target LMS PACCs, including TP53 replacement, may improve response to chemotherapy and improve outcomes for patients. Citation Format: Ryan Kennington, Gareth Mitchell, Emily Payne, Niraja Bhachech, Jonathan A. Fletcher, Ting Liu, Matt van de Rijn, Sarah Amend, Kenneth J. Pienta, Joshua D. Schiffman, Lisa M. Abegglen. Leiomyosarcoma poly-aneuploid cancer cells form in response to chemotherapy, contribute to chemoresistance, and lead to higher rates of metastatic recurrence [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 1991.

Large Congenital Granular Cell Tumor in the Newborn—Diagnosis and Management: Case Report and Literature Review

Large Congenital Granular Cell Tumor in the Newborn—Diagnosis and Management: Case Report and Literature Review

Association between pathological infiltrative tumor growth pattern and prognosis in patients with resected lung squamous cell carcinoma

IntroductionLung squamous cell carcinoma (LUSC) usually shows expansive growth with large tumor nests; few reports on invasive growth patterns (INF) in LUSC have been associated with poor prognosis in gastrointestinal and urothelial cancers. In this study, we examine the association between INF and the prognosis of LUSC. Materials and methodsWe analyzed INF as a potential prognostic factor in 254 consecutive patients with LUSC who underwent complete surgical resection at our hospital between 2008 and 2017. INF was classified into 3 categories based on the structure of the tumor other than the large round solid nest of tumor cells. ResultsINF was categorized as INFa in 59 patients (23 %) with only well-demarcated large solid tumor cell nests, INFb in 89 patients (35 %) with medium to small, alongside large solid nests, and INFc in 98 patients (39 %) with cord-like/small nests or isolated cells plus large or medium solid nests. No significant lymph node metastasis differences were observed between INFc and INFa/b tumors. However, in patients with p-stage I, INFc had a poorer prognosis with regard to recurrence-free survival (RFS), with a 5-year RFS rate of 53.3 %, compared to 74.9 % for INFa/b (p = 0.010). ConclusionOur study highlights a novel pathological concept of INF in LUSC, and contributed to the proposal that it is a factor indicating an unfavorable prognosis in patients with early-stage LUSC. A prospective multicenter study is warranted for INFc patients, as careful follow-up and adjuvant chemotherapy might lead to the early detection and prevention of recurrence.

Inter-Sphincteric Resection of Rectum for Ulcerated S-100 Negative Large Granular Cell Tumour

Non-neural granular cell tumor was first described in 1991 as an unusual primitive, polypoid variant of the conventional GCT (granular cell tumor). To date, this neoplasm remains as a rare entity and the cell of origin is uncertain. While the histological features are similar to the conventional (traditional) GCTs, it represents a distinct entity, as it is negative for S-100 and lacks true nerve sheath differentiation. We report here a case of a 49-year-old male patient with S-100 negative, vimentin positive large benign, ulcerated, bleeding non-neural GCT in the lower rectum. We confirmed the diagnosis histopathologically and immunohistochemically. We treated it by ISRR (Inter-Sphincteric Resection of Rectum) and primary colo-anal anastomosis. We find no other report of non-neural GCT located in the rectum in surgical literature. This is probably the first case of non-neural GCT identified in the rectum. This case report is presented here to document a non-neural GCT located in the rectum for the first time ever reported, and also to highlight the optimum best surgical approach, as we deemed here for this large ulcerated bleeding tumor in the rectum. This rectal non-neural GCT posed here as an unusual differential diagnosis from such more common neoplastic bleeding lesions in the rectum as carcinoma rectum, hemorrhoid, rectal polyp, etc. Here we like to discuss our experience, reviewing in brief the available literature implicating the biological behavior, histopathological and immunohistochemical features, differential diagnosis and therapeutic considerations of neural and non-neural GCTs. KYAMC Journal Volume: 14, No: 03, October 2023: 181-187.

Dedifferentiated Leiomyosarcoma of the Uterine Corpus with Heterologous Component: Clinicopathological Analysis of Five Consecutive Cases from a Single Institution and Comprehensive Literature Review.

Dedifferentiation is a very rare phenomenon in uterine leiomyosarcoma (LMS). The aim of this study was to comprehensively analyze the clinicopathological characteristics of uterine dedifferentiated LMS (DDLMS). We reviewed electronic medical records and pathology slides from five patients with uterine DDLMS and performed immunostaining. The mean age of the patients was 56 years. Two patients presented with abdominal discomfort, while in three cases the uterine tumors were detected on routine medical examination. The mean size of the tumors was 17.0 cm. Four patients underwent hysterectomy. The initial stages were distributed as IB (2/5), IIIC (2/5), and IVC (1/5). Post-operative concurrent chemoradiation therapy, radiation therapy, and chemotherapy were administered in one, one, and two patients, respectively. Despite post-operative treatment, three patients developed metastatic recurrences in the abdominal and pelvic organs. Recurrence-free survival time ranged between 4 and 30 months. Histologically, the differentiated areas demonstrated the classic morphology of malignant smooth muscle differentiation, whereas the dedifferentiated areas resembled undifferentiated pleomorphic sarcoma and were characterized by large pleomorphic tumor cells admixed with haphazardly arranged atypical cells with marked nuclear pleomorphism. All cases also exhibited heterologous components, including chondrosarcoma (CSA; 3/5) and rhabdomyosarcoma (2/5). In two cases, the heterologous components were initially detected in primary tumors. In three cases, the primary tumors did not exhibit any dedifferentiated or heterologous components. Instead, more than half of the recurrent tumors consisted of heterologous components. Three cases showed a sharp demarcation between the LMS and CSA components, while in two cases the dedifferentiated area imperceptibly merged with the differentiated component. Immunostaining revealed that the dedifferentiated components exhibited a lack of desmin immunoreactivity in three of the four examined cases. A subset of uterine LMS represents various amounts and types of dedifferentiation and heterologous components in both primary and recurrent tumors. Routine recognition of DDLMS and distinction from its mimickers are required for accurate diagnosis and further characterization of these rare tumors.

SPI1 Is the Master Regulator of the Small Cell Variant of Anaplastic Large Cell Lymphoma Controlled By Methylation of SPI1 Gene Promoter Region

Introduction The small cell variant of anaplastic large cell lymphoma (SC-ALCL) is a subtype of anaplastic lymphoma kinase (ALK)-positive ALCL characterized by chemoresistance and poor prognosis, necessitating novel treatment strategies. Recent advances in targeted therapies have resulted in significant responses in various chemoresistant hematological malignancies. Therefore, understanding the underlying oncogenic mechanisms and identifying potential therapeutic targets are critical for overcoming SC-ALCL. Immunohistochemically, SC-ALCL comprises two distinct tumor cell populations: small tumor cells demonstrating negative to weak ALK and CD30 protein expression, and large tumor cells with robust expression of these proteins. We previously reported that small tumor cells display particular resistance to chemotherapy; however, the mechanisms underlying chemoresistance and the molecular characteristics of small tumor cells remain elusive. This study aimed to elucidate the molecular attributes of small tumor cells and pave the way for the development of innovative treatment approaches. Methods We investigated the characteristics of small tumor cells using patient blood samples diagnosed with SC-ALCL leukemic presentation and publicly available RNA-seq data from eight ALK-positive ALCL cell lines. Small and large tumor cells were separated from blood samples based on CD30 expression using CD30 - a phycoerythrin antibody and a magnetic bead separation kit. The presence of the NPM-ALK fusion gene was confirmed in both populations by PCR analysis. Bulk RNA-seq analysis was performed on four samples: small and large tumor cells at the onset and at the first (mainly occupied by small tumor cells) and second (mainly occupied by large tumor cells) relapses. Gene set enrichment analysis was used to identify gene expression patterns in small tumor cells. Signature genes of small tumor cells were identified by filtering with the following thresholds: false discovery rate-adjusted P-value <0.05, and fold-change >2 compared to large tumor cells. The transcription factors regulating the signature genes of small tumor cells were predicted using the g:Profiler software. Result Bulk RNA sequencing analysis of the four blood samples revealed that the SPI1 gene was significantly upregulated in small tumor cells compared to that in large tumor cells. SPI1 has emerged as the highest-scoring transcription factor, regulating the expression of 570 genes that characterize small tumor cells. Approximately 70% of these signature genes overlapped with the SPI1 target genes. Furthermore, gene set enrichment analysis revealed that small tumor cells display increased anti-apoptotic gene activity and decreased cell proliferation gene activity. These observations were validated by integrated gene expression analysis using publicly available RNA-seq data from eight ALK-positive ALCL cell lines (Figure 1). The study found high expression of SPI1 and SPI1 targeted genes in small tumor cells, accompanied by low expression of anti-apoptotic genes in ALK-positive ALCL cell lines, which were more analogous to large tumor cells than small tumor cells. Single-cell RNA-seq analysis validated the high expression of the SPI1 gene in small tumor cells. To explore the mechanism regulating SPI1 gene expression, we examined DNA methylation patterns in the SPI1 promoter region using conventional bisulfite sequencing. Conventional bisulfite sequencing revealed a hypomethylated SPI1 promoter region in small tumor cells and a hypermethylated region in large tumor cells, potentially accounting for the differential SPI1 expression. Conclusion This study highlights SPI1gene as the master regulator determining the unique characteristics of small tumor cells in SC-ALCL. Furthermore, the regulation of SPI1 gene expression appeared to be mediated by DNA methylation patterns within the SPI1 promoter region. These findings pave the way for innovative treatment strategies for SC-ALCL such as SPI1 targeting therapy and methylation-based therapies, offering promising avenues for treating SC-ALCL.

Dentinogenic Ghost Cell Tumor: An Unusual Aggressive Oral Lesion

The purpose of this report was to document a case with a 1-week and 2-month follow up and contribute to the small body of existing literature to better understand this rare odontogenic tumor. There have been few aggressive and large dentinogenic ghost cell tumor case reports found in this literature.

Multiple skin lesions, especially on the legs, predict a poorer prognosis in skin lymphoma with large tumour cells.

Multiple skin lesions, especially on the legs, predict a poorer prognosis in skin lymphoma with large tumour cells.

THU373 Refractory Hypoglycemia In A Patient With Metastatic Cholangiocarcinoma: Abstract

Abstract Disclosure: M.G. Fernandez: None. D.J. Selen: None. Background: Nonislet cell tumor hypoglycemia is an uncommon but severe complication of cancer. It results from tumoral overproduction of insulin-like growth factor 2 (IGF-2), which inhibits hepatic glycogenolysis and the release of glucagon and growth hormone (GH). These three mechanisms can result in severe and refractory hypoglycemia. Clinical Case: We present a case of a 57-year-old female newly diagnosed with metastatic cholangiocarcinoma who was admitted to the hospital after an episode of syncope at home in the setting of hypoglycemia with a serum blood glucose of 17 mg/dL (N >60 mg/dL). During the hospital admission, evaluation of hypoglycemia included a normal TSH of 1.170 (reference range [RR] 0.3-5.5 mIU/ml), fasting morning cortisol of 23.3 (RR >14-15 μg/dL), and a negative sulfonylurea screen. In addition, the patient had an undetectable level of Insulin <3.0 (RR 3-25 mU/L), Beta-hydroxybutyrate <0.10 (RR 0.02-0.27 mMol/L), C-peptide <0.1 (RR 0.5-3.3 ng/ml), and Pro-insulin <1.6 (RR 3-20 pmol/L). CT of the abdomen revealed disease progression with innumerable bilateral enhanced hypoattenuating masses in the liver. Management for refractory hypoglycemia required nutrition optimization, nausea control, close glucose monitoring, IV dextrose infusion, and intermittent intravenous glucagon for episodes of severe hypoglycemia (<40 mg/dL). During the hospitalization, the patient received the first cycle of chemotherapy with gemcitabine, cisplatin, and dexamethasone. On day 10 of admission, the IGF-2 resulted at 120 ng/ml (RR 180-580ng/ml) and IGF-1<10 (RR 50-317 ng/ml) with an IGF-2/IGF-1 ratio greater than 100 (cut off>10), diagnostic of a large nonislet cell tumor as the most likely cause of her severe hypoglycemia. Artificial nutrition did not align with this patient’s goals of care, so she was discharged from the hospital with a FreeStyle Libre 2 for continuous glucose monitoring. However, two weeks later, she returned to the emergency department with hypoglycemia (<40 mg/dL), ultimately choosing to pursue hospice. Conclusion: Patients with large liver tumor burden can experience hypoglycemia due to low glycogen content in the liver. In addition, these patients can have decreased oral intake and weight loss, which confounds the clinical scenario and can delay diagnostic workup. Patients with refractory hypoglycemia and nonislet cell tumors require further evaluation for IGF-2 production, and alternative temporary nutritional options should be discussed with the patient immediately. Therapeutic options depend on the ability to treat underlying cancer. Palliative chemotherapy, surgery, or radiation can be considered to control the tumor and improve hypoglycemia for quality of life when the cancer is otherwise untreatable. Presentation: Thursday, June 15, 2023

Abstract 1151: CD6 isoforms improve CAR T cell fitness

Abstract The ability of chimeric antigen receptor (CAR) T cells to initiate and sustain an effective immune response entails a delicate balance between T-cell activation and deactivation and is key for complete tumor elimination. CD6 is a co-receptor that fine-tunes T cell receptor signal strength through a unique dual function intracellular domain. CD6 is alternatively spliced, creating isoforms that lack distinct regions which interact with activating or inhibitory adapter proteins, thereby delivering inhibitory or activating signals, respectively. We hypothesized that CAR T cell fitness, namely their ability to sustain their effector function, can be achieved by using alternatively spliced CD6 isoforms which lack exons responsible for inhibitory signaling. First, we discovered that overexpression of the canonical full-length CD6 molecule, isoform CD6A, resulted in marginal improvement of CAR T cell function, while its deletion using CRISPR/Cas9 depressed the antitumor CAR T cell functionality. This supported a net stimulatory role for CD6 in CAR T cell function. To study their effect on cellular fitness, we then synthesized and overexpressed known alternatively spliced cytoplasmic isoforms CD6B, CD6C, CD6D, CD6E, and CD6F on CAR T cells and, noted a significant tendency towards preserving the CAR T cell naïve and central memory compartments, upon tumor encounter. Overexpression of isoform CD6F, which lacks exon 9, and to a lesser extent isoforms CD6C and CD6E enhanced the short- and long-term cytotoxicity of HER2 and CD19 targeting CAR T cells when compared to CAR T cells alone or CAR T cells overexpressing, CD6A. Despite exhibiting a lower proliferation index, and lower CAR CD3ζ phosphorylation at rest, CD6F CAR T cells secreted significantly higher concentrations of the Th1 cytokine, IFN-γ, and mediated more sustained in vitro cytotoxicity long-term, with more complete elimination of large tumor cell loads. Lastly, in an orthotopic model of human glioblastoma, the adoptive transfer of CD6F HER2 CAR T cells induced a more significant but also more sustained anti-glioma effect that translated into a significant survival advantage for experimental animals. Our data support that the overexpression of the alternatively spliced CD6 isoforms improves CAR T cell fitness resulting in superior antitumor activity both in vitro and in vivo. Citation Format: Jessica S. Morris, Ahmed Z. Gad, Lea M. Godret-Miertschin, Ryan Fleischmann, Vita Salsman, Sujith K. Joseph, Nabil Ahmed. CD6 isoforms improve CAR T cell fitness [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 1151.

Epithelioid inflammatory myofibroblastic sarcoma: a pitfall in the differential diagnosis of ALK-positive anaplastic large cell lymphoma.

An 18-year-old female presented with a 4.5 cm abdominal mass. Biopsy showed sheet-like growth of large tumor cells with round to oval nuclei, 1-2 nucleoli, and abundant cytoplasm. Immunohistochemistry showed strong, uniform CD30 staining and cytoplasmic ALK staining. B-cell markers (CD20, CD79a, PAX5, kappa/lambda) and T-cell markers (CD2, CD3, CD4, CD5, CD43, granzyme B, T-cell receptor-β) were negative. Other hematopoietic markers (CD45, CD34, CD117, CD56, CD163, EBV) were negative, but CD138 was positive. Non-hematopoietic markers showed desmin positivity and negativity for S100, melan A, HBM45, PAX8, PAX2, WT1, MYO-D1, myogenin, pancytokeratin, and CAM5.2. Sequencing identified PRRC2B::ALK fusion. A diagnosis of epithelioid inflammatory myofibroblastic sarcoma (EIMS) was made. EIMS is a rare, aggressive form of inflammatory myofibroblastic tumor typically presenting in children and young adults. The tumor comprises large epithelioid cells that express ALK and often CD30. ALK-positive ALCL has a similar age range and also is a large-cell tumor expressing CD30 and ALK. Other ALK-positive neoplasms (e.g., carcinomas, ALK-positive large B-cell lymphoma, ALK-positive histiocytosis) typically lack CD30 and have distinct clinicopathologic features that aid diagnosis. Hematopathologists need to distinguish EIMS from ALK-positive ALCL, which frequently shows loss of pan-T-cell antigens. Careful morphologic evaluation for the hallmark cells of ALCL and comprehensive phenotyping are critical to avoid this diagnostic pitfall. If known, the ALK rearrangement partner gene may also provide diagnostic clues; for example PRRC2B::ALK and RANBP2::ALK occur in EIMS but not ALCL.

Tumor-Stroma Ratio in Basaloid and Conventional Laryngeal Squamous Cell Carcinoma: Prognostic Significance and Concordance in Paired Biopsies and Surgical Samples

Basaloid squamous cell carcinoma (BSCC) is a subtype of squamous cell carcinoma (SCC) associated with a poor prognosis. Tumor-stroma ratio (TSR) has been introduced as a prognostic feature in many solid tumors. TSR was investigated in a series of laryngeal BSCCs and compared with a group of stage-matched conventional SCCs (cSCCs), in both preoperative and surgical specimens, with the intent of ascertaining the more aggressive behavior of BSCC and verifying the presence of stromal-related causes. A series of 14 consecutive laryngeal BSCCs and a control group of 28 stage-matched conventional cSCCs were analyzed. A higher nodal metastasis presence was found in BSCCs (57.1% vs. 28.6%). The recurrence rate was 33.5% and 63.6% in the cSCC and BSCC groups; disease-free survival (DFS) was higher, though not significantly, in patients with cSCC. TSR, large cell nests, and tumor budding showed a moderate to very good agreement, and stroma type a good to very good agreement between biopsies and surgical specimens in the cSCC group. In the BSCC group, agreement was poor to very good for TSR and stroma type, and good to very good for large cell nests and tumor budding. Age was the only feature significant in predicting recurrence in the BSCC group (p = 0.0235). In cSCC, TSR low/stroma rich cases, when evaluated on biopsies or surgical specimens, were associated with lower DFS (p = 0.0036; p = 0.0041, respectively). Laryngeal BSCCs showed a lower DFS than cSCCs, even if statistical significance was not reached. TSR, evaluated in laryngeal biopsies and excised tumors, was prognostic in terms of DFS in cSCC but not in BSCC cases.

Diffuse Variant of Nodular Lymphocyte-Predominant Hodgkin Lymphoma in A 39-Year-Old Female: A Rare Case Report from Syria

Introduction: Nodular lymphocyte-predominant Hodgkin lymphoma (NLPHL) represents a rare subtype of Hodgkin Lymphoma that constitutes approximately 5% of all HL cases, with an annual incidence of 1-2 per 1,000,000. Histological diagnosis requires detecting the lymphocyte-predominant (LP) cells, characterized by their popcorn-like contours and distinct immunophenotypic features, including the expression of the B cell surface marker CD20, with negative expression of CD15 and CD30, within a characteristic tumoral microenvironment. Case Presentation: A 39-year-old Syrian female was admitted to our hospital due to a painless, palpable mass in the left axilla, accompanied by no other symptoms. Three months earlier, the patient noticed the mass and visited an external clinic, where she received a ten-day course of antibiotics without experiencing any improvement. Physical examination revealed a firm, round mass devoid of signs of inflammation. An ultrasonography was performed and identified six enlarged lymph nodes in the left axilla displaying signs indicative of malignancy. These nodes were surgically excised, and the subsequent microscopic examination unveiled a biphasic nodular and diffuse proliferation of small lymphocytes, follicular dendritic cells, and epithelioid histiocytes, mixed with large distinct tumor cells recognized as LP cells, that are characterized by multilobulated nuclei with finely granular chromatin and prominent nucleoli. Immunohistochemical examination demonstrated positive expression for CD20 and CD45 in the LP cells, along with CD57 in the background cells, with negative expression for CD15, CD30, and BCL6, while CD10, CD3, BCL2, and Cyclin D1 markers yielded inconclusive results. Consequently, the final diagnosis was confirmed as NLPHL-Diffuse variant. Conclusion: In our manuscript, we presented a diagnostically challenging case of NLPHL diffuse variant in a middle-aged otherwise healthy woman. This case emphasizes on the importance of thorough microscopic examination with the use of immunostaining to make an accurate histopathological diagnosis and thus to provide the best possible medical care in similar cases.