Tumors Of Origin Research Articles

Physico-chemical characterization of the tumour microenvironment of pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is a highly aggressive lethal malignancy that accounts for more than 90% of pancreatic cancer diagnoses. Our research is focused on the physico-chemical properties of the tumour microenvironment (TME), including its tumoural extracellular matrix (tECM), as they may have an important impact on the success of cancer therapies. PDAC xenografts and their decellularized tECM offer a great material source for research in terms of biomimicry with the original human tumour. Our aim was to evaluate and quantify the physico-chemical properties of the PDAC TME. Both cellularized (native TME) and decellularized (tECM) patient-derived PDAC xenografts were analyzed. A factorial design of experiments identified an optimal combination of factors for effective xenograft decellularization. Our results provide a complete advance in our understanding of the PDAC TME and its corresponding stroma, showing that it presents an interconnected porous architecture with very low permeability and small pores due to the contractility of the cellular components. This fact provides a potential therapeutic strategy based on the therapeutic agent size.

Transformation of G1-G2 neuroendocrine tumors to neuroendocrine carcinomas following peptide receptor radionuclide therapy.

We observed that some patients with well-differentiated neuroendocrine tumors (NET) who received peptide receptor radionuclide therapy (PRRT) with Lutetium-177 (177Lu) DOTATATE developed rapid disease progression with biopsy-proven histologic transformation to neuroendocrine carcinoma (NEC), an outcome that has not been previously described. Therefore, we conducted a retrospective review of all patients with well-differentiated G1-G2 NET who received at least one cycle of PRRT with (177Lu) DOTATATE at our center from January 2019 to December 2020. Among 152 patients, we identified 7 patients whose NET transformed to NEC. Median time from start of PRRT to transformation was 8.2 months (range: 2.6-14.4 months). All patients whose tumors underwent transformation had pancreatic tail as the primary site and had prior chemotherapy with temozolomide. No differences in the incidence of transformation were observed according to gender, race, original tumor grade, or number of prior therapies. Six patients received treatment with platinum and etoposide after transformation with two patients having partial response as best response. All patients with transformation died from progressive disease with median overall survival (OS) after transformation of 3.3 months (95% CI 2.1-4.4). Molecular testing of transformed NEC identified mutation(s) in TP53 and/or ATM in all cases. Transformation of NET to NEC following PRRT is associated with aggressive course and dismal prognosis. Patients with pancreatic tail as the primary site who had prior therapy with temozolomide may be at a higher risk. Further investigation is necessary to determine the best treatment sequence in this patient population.

Intrapericardial nonfunctional paraganglioma: a case report and literature review

Abstract Objectives Paraganglioma (PGL) is a rare extra-adrenal neuroendocrine tumor, and intrapericardial PGL is extremely rare. We report a rare case of intrapericardial nonfunctional PGL, which may be used as a reference for further analysis. Case presentation This article presents the case of a 65-year-old woman with a 2-year history of lower extremity pain. Ultrasound revealed a hypoechoic mass adjacent to the right atrium, compressing and narrowing the right atrium. Computed tomography (CT) showed a low-density mass with marked enhancement suggestive of a solitary fibrous tumor or a vasogenic tumor of pericardial origin. Cardiac magnetic resonance imaging (MRI) confirmed the location and provided a primary diagnosis of solitary fibrous tumor, hemangioma, or hemangiosarcoma. The patient eventually underwent pericardial tumor resection, and the diagnosis of PGL was confirmed by postoperative histopathology. Conclusions Pathology is considered the gold standard for the diagnosis of PGL. Imaging examinations can provide valuable information for the diagnosis and management of intrapericardial PGL, and surgery remains the treatment of choice.

Integrating cfDNA liquid biopsy and organoid-based drug screening reveals PI3K signaling as a promising therapeutic target in colorectal cancer

BackgroundThe current precision medicine relies on biomarkers, which are mainly obtained through next-generation sequencing (NGS). However, this model failed to find effective drugs for most cancer patients. This study tried to combine liquid biopsy with functional drug tests using organoid models to find potential drugs for cancer patients.MethodsColorectal cancer (CRC) patients were prospectively enrolled and blood samples were collected from patients before the start of treatment. Targeted deep sequencing of cfDNA samples was performed using a 14-gene panel. Gastrointestinal (GI) cancer organoids were established and PI3K and mTOR inhibitors were evaluated on organoid models.ResultsA total of 195 mutations were detected across 58 cfDNA samples. The most frequently mutated genes were KRAS, TP53, PIK3CA, and BRAF, all of which exhibited higher mutation rates than tissue biopsy. Although 81% of variants had an allele frequency of less than 1%, certain mutations in KRAS, TP53, and SMAD4 had high allele frequencies exceeding 10%. Notably, among the seven patients with high allele frequency mutations, six had metastatic tumors, indicating that a high allele frequency of ctDNA could potentially serve as a biomarker of later-stage cancer. A high rate of PIK3CA mutation (31 out of 67, or 46.3%) was discovered in CRC patients, suggesting possible tumor progression mechanisms and targeted therapy opportunities. To evaluate the value of anti PI3K strategy in GI cancer, different lines of GI cancer organoids were established. The organoids recapitulated the morphologies of the original tumors. Organoids were generally insensitive to PI3K inhibitors. However, CRC-3 and GC-4 showed response to mTOR inhibitor Everolimus, and GC-3 was sensitive to PI3Kδ inhibitor Idelalisib. The CRC organoid with a PIK3CA mutation showed greater sensitivity to the PI3K inhibitor Alpelisib than wildtype organoids, suggesting potential treatment options for the corresponding patients.ConclusionLiquid biopsy holds significant promise for improving precision treatment and tumor prognosis in colorectal cancer patients. The combination of biomarker-based drug prediction with organoid-based functional drug sensitivity assay may lead to more effective cancer treatment.

Abstract A006: Cancer origin tracing and timing in two high risk prostate cancers using multisample whole genome analysis: Potential clinical value

Abstract Prostate cancer (PrCa) genomic heterogeneity causes resistance to therapies such as androgen deprivation. Such heterogeneity can be deciphered in the context of evolutionary principles, but current clinical trials do not include evolution as an essential feature. Understanding the evolution of an individual PrCa through serial analysis in space and time may be more important than identifying actionable targets for therapy from single samples as in current practice. The most prominent recent example of this is our recent evolution-based discovery of subclone eradication in a metastatic PrCa, with subsequent identification of a novel method to compare eradicated and resistant subclones to better resolve actionable targets for therapy. Whether or not analysis of genomic data in an evolutionary context in primary prostate cancer can provide unique added value in the research and clinical domains remains an open question. We used novel processing techniques to obtain whole genome data together with 3D anatomic and histomorphologic analysis in two men (GP5 and GP12) with high risk PrCa undergoing radical prostatectomy. A total of 22 whole genome-sequenced sites (16 primary cancer foci and 6 lymph node metastatic) were analyzed using evolutionary reconstruction tools and spatio-evolutionary models. Probability models were used to trace spatial and chronological origins of the primary tumor and metastases, chart their genetic drivers, and distinguish metastatic and non-metastatic subclones. In patient GP5, CDK12 inactivation was among the first mutations, leading to a PrCa tandem duplicator phenotype and initiating the cancer around age 50, followed by rapid cancer evolution after age 57, and metastasis around age 59, five years prior to prostatectomy. In patient GP12, accelerated cancer progression was detected after age 54, and metastasis occurred around age 56, three years prior to prostatectomy. Multiple metastasis-originating events were identified in each patient and tracked anatomically. Metastasis from prostate to lymph nodes occurred strictly ipsilaterally in all 12 detected events. In this pilot, metastatic subclone content analysis appears to substantially enhance identification of key drivers. Evolutionary analysis’ potential impact on therapy selection appears positive in these pilot cases. Taken together with our recent discovery that solid tumor subclones can be eradicated, and that comparison of eradicated and resistant subclones could guide therapy, we believe the case for embarking on clinical trials testing evolutionary-analysis informed PrCa care is compelling. PrCa evolutionary analysis allows tracking of anatomic site of origin, timing of cancer origin and spread, and distinction of metastatic-capable from non-metastatic subclones. This enables better identification of actionable targets for therapy. If extended to larger cohorts, it appears likely that similar analyses could add substantial biological insight and clinically relevant value. Citation Format: Anssi Nurminen, Serafiina Jaatinen, Sinja Taavitsainen, Gunilla Högnäs, Tom Lesluyes, Naser Ansari-Pour, Teemu Tolonen, Kerstin Haase, Antti Koskenalho, Matti Kankainen, Juho Jasu, Hanna Rauhala, Jenni Kesäniemi, Tiia Nikupaavola, Paula Kujala, Irina Rinta-Kiikka, Jarno Riikonen, Antti Kaipia, Teemu Murtola, Teuvo L. Tammela, Tapio Visakorpi, Matti Nykter, David C. Wedge, Peter Van Loo, G. Steven Bova. Cancer origin tracing and timing in two high risk prostate cancers using multisample whole genome analysis: Potential clinical value [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Translating Cancer Evolution and Data Science: The Next Frontier; 2023 Dec 3-6; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84(3 Suppl_2):Abstract nr A006.

Efficacy and safety of the combination of cisplatin plus nab-paclitaxel and nivolumab with radiotherapy after maximal tumor resection in non-metastatic muscle invasive bladder cancer (CNN-BC trial).

TPS723 Background: The therapeutic gold standard for muscle invasive bladder cancer (MIBC) is radical cystectomy (RC) preceded by neoadjuvant chemotherapy when appropriate. However, RC is a major surgery procedure with 13% rate of severe complication and a perioperative mortality rate of about 1.5 - 5 %. Trimodal therapy (TMT) is a “bladder sparing” option alternative to RC. TMT consists of complete transurethral bladder tumor resection (TURBT) followed by a combination of systemic chemotherapy and locoregional radiotherapy (RT), with the option of “salvage” cystectomy in case of local treatment failure. Immunotherapy with anti-PD1/PD-L1 monoclonal antibody significantly improves survival of metastatic BC patients, and it seems to potentiate the activity of RT without increased toxicity. Therefore, we investigate the role of a multimodal TMT strategy to increase the disease-free survival (DFS) and avoid or delay RC in non-metastatic MIBC pts. Methods: CNN-BC trial (NCT05203913) is a phase 2, open-label, mono-institutional study evaluating the activity and safety of TMT with cisplatin, nab-paclitaxel and nivolumab as systemic therapy in non-metastatic MIBC pts. Eligible pts should have undergone complete TURBT with diagnosis of T2-T3 N0M0 urothelial carcinoma, and no evidence of lymph nodes or metastatic disease at FDG-PET within 6 weeks from the start of treatments. TMT consists of nivolumab (480 mg IV every 4 weeks for a total of 13 doses), weekly nab-paclitaxel (60mg/m2) plus cisplatin (20mg/m2) administered concurrently with RT (60Gy in 25 fractions over 5 weeks on original bladder tumor, plus a concomitant boost of 50Gy in 25 fractions on whole bladder and pelvic nodes). The primary endpoint is the 1-year DFS rate, defined as the rate of survival free of recurrence in pelvic nodes or bladder, or appearance of distant metastases. Secondary endpoints include: the rate of pts who require salvage cystectomy, the rate of locoregional complete response (CR) and of locoregional DFS, median DFS, safety, and quality of life. Exploratory biomarkers analysis will be performed. The trial is actively recruiting. Clinical trial information: NCT05203913 .

Abstract A060: Organoid Culture as a Unique Resource for Studying Aggressive Triple Negative Breast Cancer in African American

Abstract Introduction Triple negative breast cancer (TNBC) among women with African ancestry has been shown to be more aggressive than in women of European ancestry. However, the root cause for this disparity is not fully understood. In our previous studies, we show that the gene expression in the breast cancer stem cells of TNBC tumors was differential based on Western sub-Saharan ancestry. To study the role of African ancestry in the biology of TNBC, we have developed patient-derived organoids (PDO) from African (Ghanaian) and African American tumors that will be available for research. Organoid culture has the capacity to mimic the physiological tissue organization and functionality and has been used as an invaluable tool for disease modeling and drug discovery. Objective The objective is to develop and characterize PDOs based on African TNBC that will serve as a renewable source of African tumors for breast cancer research. Methods Through our international collaboration called Precision Medicine for Aggressive Breast Cancers (PMABC), we obtained fresh patient tumors from continental Africa (Ghana) and African American tumors from Henry Ford Health. PDOs were developed form both primary tumors and patient-derived xenografts (PDX). Tissues were processed using the Miltenyi Gentle Mac. The cells were seeded in a 12-well plate coated with Matrigel. Developed organoids are characterized using single cell RNA sequencing as well as 10X spatial sequencing Results We have successfully developed organoids using frozen tissues from both West African and African American breast patients. We have successfully established four (4) organoid lines from individual primary breast cancer tissues and one PDX. The organoids are passaged after every 7-14 days, and the highest passage so far is passage number 12 for the organoids from primary tissues and passage number 15 for the PDXs. We are in the process of characterizing the developed organoids using single-cell assay in comparisons to their primary tumor of origin. Conclusion Establishment of organoids has helped us have a renewable source of tumor for studying the aggressive TNBC among Women with African ancestry. We aim to use the organoids to identify tumor biomarkers for treating aggressive TNBC that disproportionately affects women of western sub Saharan ancestry. Citation Format: Moses Kamita, Kurt Fernando, Sylvester Antwi, Forster Amponsah-Manu, Josephine Nsaful, Kafui Akakpo, Jessica Bensenhaver, Kwabena Agbedinu, Michael Nortey, Nelson Affram, Mohammed Sheriff, Cassandra Mills, Alex Mremi, Jieoma Aja, Moses Dokurugu, Haythem Ali, Eleanor Walker, Max Wicha, Evelyn Jiagge. Organoid Culture as a Unique Resource for Studying Aggressive Triple Negative Breast Cancer in African American [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Breast Cancer Research; 2023 Oct 19-22; San Diego, California. Philadelphia (PA): AACR; Cancer Res 2024;84(3 Suppl_1):Abstract nr A060.

Histopathologic and immunophenotypic characterization of patient-derived pediatric malignant hepatocellular tumor xenografts (PDXs)

Advances in targeted therapies for pediatric hepatocellular tumors have been limited due to a paucity of clinically relevant models. Establishment and validation of intrahepatic patient-derived xenograft (PDX) models would help bridging this gap. The aim of this study is to compare the histomorphologic and immunophenotypic fidelity of patient tumors and their corresponding intrahepatic PDX models. Murine PDX models were established by intrahepatic implantation of patient tumors. Pathology slides from both patients and their corresponding PDX models were reviewed and quantitatively assessed for various histologic components and immunophenotypic markers. Ten PDX models were successfully established from nine patients with pre- (n=3) and post- (n=6) chemotherapy samples; diagnosed of hepatoblastoma (n=8) and hepatocellular neoplasm, not otherwise specified (n=1). Two of nine (22.2%) patients showed ≥75% fetal component; however, the corresponding PDX models did not maintain this fetal differentiation. High grade histology was seen in three patients (33.3%) and overrepresented in six PDX models (60%). Within the subset of three PDXs that were further characterized, significant IHC concordance was seen in all 3 models for CK7, CK19, Ki-67, and p53; and 2 of 3 models for Sox9 and Beta-catenin. GPC-3 and GS showed variable to moderate concordance, while Hepar was the least concordant. Our study shows that in general, the PDX models appear to represent the higher-grade component of the original tumor and show significant concordance for Ki-67, making them appropriate tools for testing new therapies for the most aggressive, therapy-resistant tumors.

Establishment of Nomogram for Prediction of Hearing Preservation after Retrosigmoid Approach in Patients with Vestibular Schwannoma.

To derive and validate a prognostic nomogram for the prediction of hearing preservation (HP) after retrosigmoid approach (RSA) in patients with vestibular schwannoma (VS) and further assist in clinical decision-making. Retrospective study. Tertiary referral center. A total of 111 patients diagnosed with VS with serviceable hearing from January 2013 to March 2023. All patients underwent surgery via RSA, and hearing outcomes were reviewed 2 weeks postoperatively. Preoperative and postoperative hearing were analyzed and stratified according to the American Academy of Otolaryngology-Head and Neck Surgery (AAO-HNS). In multivariate analysis of the primary group, preoperative hearing, tumor size, and tumor origin were significantly related to postoperative HP ( p = 0.029, p = 0.043, and p = 0.018, respectively). Factors derived from the multivariate analysis were all assembled into the nomogram. The receiver operating characteristic (ROC) curves showed good predictive accuracy of the nomogram model in both primary and validation groups with area under the ROC curve (AUC) values of 0.802 and 0.797, respectively. Independent predictors of postoperative HP in patients with VS were selected to create the nomogram. The nomogram was able to stratify patients into different risk groups and assist in clinical decision making.

Oral Lymphangioma: An Original Series of Three Cases with Review

Lymphangiomas are benign hamartomatous tumors of lymphatic origin which results from sequestration of lymphhatic tissues that do not communicate with other lymphatic channels. They may occur with hemangiomas and have high predilections for head and neck region (50-70%). They may occur at birth (60-70%) or till two years of age (90%) and rarely in adults. The most common site of occurrence in the mouth is dorsum of tongue being followed by lips, buccal mucosa, soft palate and floor of mouth. Tongue lymphangioma may present as localized or diffused growth that may result in macroglossia, impaired speech and difficulty in mastication. There are different treatment options; surgical excision being the most effective mode of treatment. Here we have reported three different cases of oral lymphangiomas, two of which occurring in the tongue and one in the buccal mucosa.

Follicular adenoma with a papillary architecture originating from an ectopic thyroid gland: a case report

BackgroundFollicular adenomas with papillary architecture are rare tumors of thyroid origin and are composed of completely encapsulated follicular cells with a papillary architecture lacking the nuclear characteristics of papillary carcinoma. Herein, we present a case of follicular adenoma with papillary architecture originating from an ectopic thyroid gland, diagnosed from a mass in the submandibular region.Case PresentationA 70-year-old woman was referred to our hospital with the chief complaint of a painless left submandibular mass that had been present for one year. The patient underwent left submandibular dissection for therapy and diagnosis. Microscopically, papillary lesions with fibrovascular cores were observed in the interior, and the epithelial cells were cylindrical in shape with eosinophilic cytoplasm, round or oval nuclei, with no pathological features, leading to a diagnosis of papillary carcinoma or follicular carcinoma. The mass was diagnosed as a follicular thyroid adenoma with papillary architecture. This is the first report of a follicular adenoma with a papillary architecture originating from an ectopic thyroid gland.ConclusionThis experience suggests that follicular adenoma should be included in the differential diagnosis of ectopic thyroid tumors.

Extensive Chest Wall Metastasis Revealing Follicular Thyroid Carcinoma

Introduction: Chest wall tumors are a heterogeneous group of rare lesions, arising from any soft tissue or bony structure in the thoracic cavity. They may present as primary or metastatic tumors. Metastatic chest wall tumor from a primary thyroid carcinoma is extremely rare. Case report: We report a challenging case of a 69 years-old female patient, with a follicular thyroid carcinoma revealed by chest wall tumor measuring 81 x 64 x 64 cm. The patient underwent a biopsy of the chest wall mass concluding to thyroid tumoral origin, then she had a total thyroidectomy and lymph node dissection. A tumorectomy of the chest wall lesion is planned before RAI therapy. Conclusions: The case of a metastatic lesion originating from a primary thyroid carcinoma not previously known is one manifestation of the condition defined as occult thyroid carcinoma. Metastatic follicular thyroid cancer has poor prognosis, especially when metastases are the first manifestation revealing the diagnosis, which is a sign of advanced disease stage with limited chances of achieving remission.

Research progress of CTC, ctDNA, and EVs in cancer liquid biopsy

Circulating tumor cells (CTCs), circulating tumor DNA (ctDNA), and extracellular vehicles (EVs) have received significant attention in recent times as emerging biomarkers and subjects of transformational studies. The three main branches of liquid biopsy have evolved from the three primary tumor liquid biopsy detection targets—CTC, ctDNA, and EVs—each with distinct benefits. CTCs are derived from circulating cancer cells from the original tumor or metastases and may display global features of the tumor. ctDNA has been extensively analyzed and has been used to aid in the diagnosis, treatment, and prognosis of neoplastic diseases. EVs contain tumor-derived material such as DNA, RNA, proteins, lipids, sugar structures, and metabolites. The three provide different detection contents but have strong complementarity to a certain extent. Even though they have already been employed in several clinical trials, the clinical utility of three biomarkers is still being studied, with promising initial findings. This review thoroughly overviews established and emerging technologies for the isolation, characterization, and content detection of CTC, ctDNA, and EVs. Also discussed were the most recent developments in the study of potential liquid biopsy biomarkers for cancer diagnosis, therapeutic monitoring, and prognosis prediction. These included CTC, ctDNA, and EVs. Finally, the potential and challenges of employing liquid biopsy based on CTC, ctDNA, and EVs for precision medicine were evaluated.

MHC-I upregulation safeguards neoplastic T cells in the skin against NK cell-mediated eradication in mycosis fungoides

Cancer-associated immune dysfunction is a major challenge for effective therapies. The emergence of antibodies targeting tumor cell-surface antigens led to advancements in the treatment of hematopoietic malignancies, particularly blood cancers. Yet their impact is constrained against tumors of hematopoietic origin manifesting in the skin. In this study, we employ a clonality-supervised deep learning methodology to dissect key pathological features implicated in mycosis fungoides, the most common cutaneous T-cell lymphoma. Our investigations unveil the prominence of the IL-32β–major histocompatibility complex (MHC)-I axis as a critical determinant in tumor T-cell immune evasion within the skin microenvironment. In patients’ skin, we find MHC-I to detrimentally impact the functionality of natural killer (NK) cells, diminishing antibody-dependent cellular cytotoxicity and promoting resistance of tumor skin T-cells to cell-surface targeting therapies. Through murine experiments in female mice, we demonstrate that disruption of the MHC-I interaction with NK cell inhibitory Ly49 receptors restores NK cell anti-tumor activity and targeted T-cell lymphoma elimination in vivo. These findings underscore the significance of attenuating the MHC-I-dependent immunosuppressive networks within skin tumors. Overall, our study introduces a strategy to reinvigorate NK cell-mediated anti-tumor responses to overcome treatment resistance to existing cell-surface targeted therapies for skin lymphoma.

177Lu]Lu-DOTA-TATE in newly diagnosed patients with advanced grade 2 and grade 3, well-differentiated gastroenteropancreatic neuroendocrine tumors: Primary analysis of the phase 3 randomized NETTER-2 study.

LBA588 Background: Currently, there is no universally accepted first line (1L) therapy for higher grade, well-differentiated gastroenteropancreatic neuroendocrine tumors (GEP-NETs) and an unmet medical need remains in these patients (pts). Radioligand therapy (RLT) is an innovative cancer treatment that crosses the traditional domains of systemic, radiation or surgical therapies. The Phase 3 NETTER-2 study (NCT03972488) evaluated [177Lu]Lu-DOTA-TATE (hereafter 177Lu-DOTATATE) as 1L treatment in pts with Grade (G) 2 and G3 advanced GEP-NETs. This is the first trial to assess 1L RLT in any solid tumor. Methods: Eligible pts were newly diagnosed with somatostatin receptor-positive high G2 or G3 (Ki-67 ≥10% and ≤55%) advanced GEP-NETs within the last 6 months prior to enrollment. Pts were randomized (2:1) to receive 4 cycles of 177Lu-DOTATATE (4 × 7.4 GBq) plus 30 mg octreotide long-acting release (LAR) at 8-weekly intervals during 177Lu-DOTATATE treatment then every 4 weeks (177Lu-DOTATATE arm), or 60 mg octreotide LAR every 4 weeks (control arm), stratified by grade (G2 vs G3) and tumor origin (pancreas vs other). The primary endpoint was progression-free survival (PFS), centrally assessed using RECIST 1.1. Objective response rate (ORR), a key secondary endpoint, was tested hierarchically after PFS. Results: Overall, 226 pts were randomized to the 177Lu-DOTATATE (n = 151) or control (n = 75) arms. Most tumors originated in the pancreas (54.4%) or small intestine (29.2%); G3 tumors were reported in 35.0% of pts. Median cumulative dose of 177Lu-DOTATATE was 29.2 GBq, with 87.8% of pts receiving all 4 doses. Median PFS (95% confidence interval [CI]) was significantly prolonged by ~14.3 months from 8.5 months (7.7, 13.8) in the control arm to 22.8 months (19.4, not estimable) in the 177Lu-DOTATATE arm; stratified hazard ratio 0.276 (95% CI: 0.182, 0.418; p < 0.0001). The ORR was significantly higher in the 177Lu-DOTATATE arm (43.0%) vs the control arm (9.3%); stratified odds ratio 7.81 (95% CI: 3.32, 18.4; p < 0.0001). PFS and ORR results were consistent across all pre-specified demographic and prognostic subgroups. Among adverse events of special interest to RLT, G3/4 leukopenia, anemia and thrombocytopenia occurred in ≤3 pts each in the 177Lu-DOTATATE arm. One case of myelodysplastic syndrome was reported (177Lu-DOTATATE arm). Conclusion: 177Lu-DOTATATE significantly prolonged PFS and demonstrated a clinically meaningful ORR, compared with high-dose octreotide LAR, in pts with newly diagnosed advanced G2 and G3 GEP-NETs. Safety was in line with the established profile of 177Lu-DOTATATE. This is the first randomized study to demonstrate efficacy of RLT as 1L treatment in any malignancy and will change clinical practice. Further investigations of RLT as a therapeutic option in other settings is warranted. Clinical trial information: NCT03972488 .

Real-world data of TAS-102 therapy in refractory metastatic colorectal cancer (mCRC): The experience of the University Hospital of Montreal (CHUM).

137 Background: Colorectal cancer poses a substantial healthcare burden due to its elevated rates of diagnosis and mortality. Managing refractory metastatic cases remains a challenge in our practice due to the paucity of therapeutic options. Treatment with Trifluridine-Tipiracil (TAS-102) prolonged overall survival among patients (pts) with mCRC. This study investigates the efficacy of TAS-102 therapy in this patient population and explores various prognostic factors influencing clinical outcomes. Methods: We retrospectively reviewed the data of 53 patients with refractory mCRC treated with at least 1 cycle of TAS-102 at CHUM between March 2018 and January 2023. Multivariate and univariate analyses were employed to evaluate the impact of age, number of prior treatments, presence of KRAS mutation, gender, tumor origin, and Eastern Cooperative Oncology Group (ECOG) performance status on progression-free survival (PFS) and overall survival (OS). Survival analysis was conducted using the Kaplan-Meier method, and Cox regression analysis assessed prognostic factors. Results: The median age was 61 years (23-82), and 27 pts (50.9%) were females. Twenty-two pts (41.5%) had their primary tumor located in the left colon, 17 pts (32.1%) had right-sided tumors, and 14 pts (26.4%) with rectal tumors. 52% of pts received TAS-102 after 2 lines of therapy and 43% beyond third line. The performance status was: ECOG 0/1 in 46 pts (86.8%), and ECOG 2 in 7 pts (13.2%). In our refractory mCRC pts, median PFS was 3 months and median OS 7 months. Univariate analysis demonstrated no significant differences in PFS or OS based on patient sex, KRAS mutation status, tumor sidedness, or the number of prior treatments. In univariate and multivariate analysis ECOG 0/1 pts compared to ECOG 2 pts had a significant improvement in both PFS (HR = 0.33; p = 0.0511) and OS (HR = 0.21; p = 0.0086). Conclusions: In our real-world experience, clinical outcomes were comparable to the findings from the RECOURSE trial, suggesting improved PFS and OS with TAS-102 in heavily pre-treated mCRC patients. ECOG performance status remains a significant prognostic factor and underscores its importance in treatment decisions for this patient population.

Clinicopathological features and clinical outcomes in individuals with Krukenberg tumors of colorectal origin.

191 Background: Krukenberg tumors (KT) are metastases to the ovary generally originating from a gastrointestinal primary such as colorectal carcinoma. The prognosis is poor with KT, and clinicopathological features associated with clinical outcomes have not been extensively studied. The study aimed to investigate the associations of clinicopathological features with outcomes in patients with KT of colorectal carcinoma (CRC) origin. Methods: This retrospective study utilized medical records and patient registries to identify 160 patients with a confirmed histopathological diagnosis of KT at Stanford University Medical Center between 2000 and 2020. Data collection included demographics, historical, clinicopathological, treatment and outcome variables. The primary tumor type was (N, %): CRC (101, 63.1%); gastric (24, 15%), breast (13, 8.1%); small bowel (10, 6.2%), other (12, 7.5%). Statistical analysis was performed using Chi-squared, Mann-Whitney U, and log-rank Kaplan-Meier analysis. Results: Analysis of the CRC cohort subdivided by location of the primary, N: 45 vs. 56, right colon (R) vs. left colon (L) revealed no significant difference in median age at diagnosis of KT, race/ethnicity, oligometastatic disease, histopathological differentiation or ovarian tumor volume. Patients with R vs L sided CRC primaries had a higher proportion of synchronous presentation at the time of KT diagnosis (75.6% vs 41.1%, R vs L, p<0.001). Time to progression was not different, but overall survival (OS) was shorter in R CRC (767 vs. 1246 days, R vs. L, p <0.01). By Kaplan-Meier analysis, patients with R CRC had a shorter OS (log-rank p=0.016). In the subgroup with unilateral KT, R sided CRC primaries involved the R ovary (85%) whereas L-sided CRC primaries involved the L ovary (70%) ( χ2, p<0.002). Patient with bilateral (B) versus unilateral (U) had a larger ovarian tumor volume (2,073cm3 vs. 307 cm3, p<0.01) but no difference in oligometastatic disease, chronicity, time to progression or overall survival. There was no statistical difference (p=0.93) between the association of bilateral KT inter-ovarian tumor size and CRC Laterality within individual patients. Conclusions: In this study, KT tumors predominantly originate from CRC. The clinical features of R versus L CRC, such as chronicity and OS are conveyed prognostically in patients with KT. Individuals with L CRC exhibited a better overall prognosis compared to those with R CRC. In patients with unilateral KT metastasis to ipsilateral ovary is significantly associated with location of CRC and is suggestive of a retrograde lymphatic or transcoelomic route of metastatic spread. Further studies are needed to confirm these findings and to elucidate ovarian organ tropism mediators that facilitate development and growth in metastatic ovarian cancer.

Real-world effectiveness and safety of pembrolizumab in mismatch repair-deficient (dMMR) gastrointestinal non-colorectal tumors.

733 Background: The KEYNOTE-158 trial demonstrated durable clinical efficacy with pembrolizumab in long-term follow-up of previously treated unresectable or metastatic MSI-H/dMMR non-colorectal cancer. Our study, the GAIN study, aims to evaluate effectiveness and safety of pembrolizumab in dMMR Gastrointestinal Non-Colorectal Tumors in real-world clinical practice. Methods: We conducted a multicenter, retrospective, observational study on patients with Mismatch Repair-Deficient (dMMR) Gastrointestinal Non-Colorectal Tumors treated with pembrolizumab in real-world practice at six university hospitals affiliated with the Galician Research Group on Digestive Tumors (GiTUD) in Northwest Spain. Results: Between January 2018 and April 2023, 35 patients were enrolled. The median age was 66 years (range 33-88), with 54.3% being male. Tumor locations included 23 (65.7%) gastroesophageal adenocarcinomas, 3 (8.6%) pancreatic adenocarcinomas, 2 (5.7%) duodenal adenocarcinomas, 2 (5.7%) intrahepatic cholangiocarcinoma, 2 (5.7%) jejune adenocarcinomas, 2 (5.7%) esophageal squamous cell carcinomas, and 1 (2.8%) tumor of unknown origin. 54.3% of tumors were poorly differentiated. The most frequent alteration was the loss of MLH1-PMS2 expression (71.4%). By tumor location, 100% of gastroesophageal, jejune, and unknown origin tumors showed MLH1-PMS2 loss; while 100% of duodenal, pancreatic, and biliary tumors exhibited MSH2-MSH6 loss. All patients received pembrolizumab, with 57.1% having no prior metastatic disease treatment, 80% having ECOG PS0-1, and 31.4% having hepatic metastases. Among 33 evaluable patients, the overall response rate (ORR) was 81.8% (including 30.3% complete response) and the disease control rate (DCR) was 90.9%. Specifically, in gastroesophageal adenocarcinomas, the ORR was 81%, and the DCR was 90.5%. In the overall population, the median progression-free survival (PFS) was 34.76 months (95% CI 5.33 – 64.19 months), and the median overall survival (OS) was 39.75 months (95% CI 4.33-75.18 months). Treatment was well-tolerated; only 3 patients discontinued treatment due to nephritis, sarcoidosis-like symptoms, or diarrhea. No treatment-related deaths occurred. Conclusions: Our study underscores the real-world effectiveness of pembrolizumab in patients with dMMR Gastrointestinal Non-Colorectal Tumors. The high ORR, DCR, and favorable safety profile support its use in this challenging patient group, providing valuable real-world evidence for clinical decision-making.

Comprehensive genomic profiling of squamous cell carcinoma of unknown primary presenting with liver metastases.

755 Background: Carcinomas of unknown primary (CUPs) are comprised of metastatic cancers for which a primary tumor of origin cannot be identified despite a full diagnostic workup. They frequently present with liver metastases, which portend a poor prognosis. Strategies employing comprehensive genomic profiling (CGP) to identify targeted treatments for CUPs have shown potential. Despite this, the molecular landscape of squamous cell carcinomas of unknown primary (SCCUPs) remains poorly defined. This study describes the results of CGP testing in patients with SCCUPs identified in the Foundation Medicine, Inc. database, with a focus on those with liver involvement. Methods: Cases of SCCUPs with FoundationOne CDx (F1CDx) assay results were identified based on a reported diagnosis of CUP and the presence of SCC histology. Cases then underwent central pathologist review and were excluded if a known primary site could be determined based on histology and disease location. Cases with liver involvement were selected based on the site of tissue biopsy. Genomic analyses of identified cases were assessed using the FoundationCORE database. Results: Sixty-nine cases of SCCUP presenting with liver involvement were identified. Alterations were observed in 102 of 324 (31.5%) genes evaluated by the F1CDx assay in at least 1 patient. The most frequently altered genes were TP53 (66.7%) , CDKN2A (33.3%) , CDKN2B (23.2%) , KRAS (21.7%; 0% G12C) , PIK3CA (18.8%), NFE2L2 (11.6%), SOX2 (11.6%), M2M2 (10.1%), and MTAP (10.1%). No patients had microsatellite instability-high disease, only 6 (8.7%) patients had a tumor mutational burden (TMB) ≥ 10, and 11 (15.9%) patients had evidence of HPV infection. Among 33 patients with available PDL-1 testing results, 7 (21.2%) had high-positive expression. An additional 374 cases of SCCUP were identified with involvement outside of the liver. Compared to these cases, patients presenting with liver involvement had less genomic alterations per tumor (5.10 vs 6.71, p=0.005), and were less likely to have TMB ≥ 10 (8.7% vs 38.0%; odds ratio [OR] 0.16, p<0.001). KRAS mutations were observed in 21.7% of those presenting with liver metastases compared to 8.3% of other SCCUP patients (OR 3.07, p=0.07). Conclusions: SCCUPs presenting with liver metastases had reduced numbers of genomic alterations and decreased TMB compared to other SCCUPs, suggesting these tumors may be less likely to respond to immunotherapy. Despite this, 36.2% of these patients had at least one alteration that could potentially guide targeted treatment decisions including entry into biomarker-driven clinical trials. Interestingly, there was a trend toward increased KRAS alterations in those with liver metastases. To our knowledge, this is the first report that describes the genomic landscape of SCCUPs presenting with liver metastases.

Patient-derived biliary tract cancer organoid biobank: Is personalized medicine utilizing organoids feasible for patients with cholangiocarcinoma?

533 Background: Cholangiocarcinoma (CC) is an aggressive malignancy with an all stage 5-year survival rate of less than 15%. Preclinical research is of pivotal importance to acquire a deeper understanding of CC and improve outcomes. The establishment of CC organoids has previously been described to be difficult due to fewer driver mutations and limitations in the ability to mimic tumor microenvironment. The aim of this study was to develop a successful culturing system for CC organoids that preserves intratumoral heterogeneity, and in turn, to determine the feasibility of personalized medicine in patients with CC using organoids. Methods: From 2020-2023, 75 CC tumor samples were prospectively collected from 65 patients. The tumors were sequenced using MSK-IMPACT, a targeted next generation sequencing (NGS) platform. Samples were processed, and organoids were generated and cultured following a standardized protocol. The organoids were grown in three different types of enriched media (M1, M2, and M3). Once cultures were adequately expanded, organoid lines were sequenced using MSK-IMPACT and/or MiSeq, a benchtop NGS platform. Mutations of the organoid line were compared to that of the tumor of origin to determine tumor enrichment. To ascertain genotypic association with organoid formation, we examined frequencies of driver mutations of interest. Logistic regression was used to assess the univariate association between mutations of interest and organoid establishment. Two-sided p-values less than 0.05 were considered to be significant. Results: Of the 75 samples collected, 24 (32%) were extrahepatic CC tumors, and the remaining were of intrahepatic origin. 92% of the samples were collected from primary tumors, and 71% of the samples were chemotherapy naïve. 64 samples successfully grew organoids. Upon evaluation of MSK-IMPACT and MiSeq data, 11 of the 64 samples were noted to retain the mutations of the tumor of origin in organoid culture; the overall success rate of tumor organoid formation was 14.6% (11/75). Tumor enrichment of organoid lines was most commonly achieved using M3 (9 out of 11 samples), the median passage at which tumor enrichment occurred was 8 (interquartile range (IQR) 2-10), indicating that the approximate median time to tumor organoid formation was 16 weeks (IQR 4-20 weeks). There was no statistically significant association between driver mutations and organoid establishment. Conclusions: Intratumoral heterogeneity of cholangiocarcinoma is maintained in organoid culture. This preclinical model potentially recapitulates the clinical features of the disease seen in humans. However, prolonged duration and low success rate of tumor enrichment makes it a less appealing avenue for personalized medicine.