Primary Tumor Specimens Research Articles

Installment of Automation and Modernized Culture Methods Updates a Drug-Sensitivity Screening Platform and Paves the Way to Next-Generation of Precision Medicine

Since the field of drug discovery has seen a rise in the use of primary tumor specimens (PTS) derived from patients with hematological malignancies as live materials in ex vivo drug treatments in late 2010s, they have discovered many intriguing phenotypes of AML cells that can lead to therapeutic insights of this disease category. However, when we consider the fact that current methods in ex vivo drug screenings are not using the most updated culture and cell processing methodology, it is highly expected that modernization of cell processing and analyzing procedures will enable us to detect phenotypes of PTS at a higher resolution. Herein, we have installed our own updated methods in multimodal categories. Even though the number of primary tumor specimens in the screening cohort is not comparable to the ones in other studies using AML PTS, (24 cases of AML, 3 cases of CML, and 1 case of MPN, while we ongoingly recruit more cells), our approach is characterized by its full-automation both in cell processing and data acquisitions using multicolor flow cytometry, as well as updated ex vivo culture methods after optimization using different culture media. We harvested cells for flow cytometry as of day 0, 3, and 6. In a monotherapy section, 24 compounds (6 conventional chemotherapy drugs, 10 epigenetic inhibitors, 4 kinase inhibitors including a FLT3 inhibitor, 3 signal transduction inhibitors, and Venetoclax) were included, while 3 different combination therapies (IDR+ AraC, Ven + 5-Aza, and Ven + AraC) were performed using 6x6 matrix layouts. Drugs were prepared in 384-well plates using a computationally controlled drug dispenser. Using those updated systems, we could discover; 1) Those fully-automated high-throughput platform needs their own optimizations regarding seeding numbers, liquid handling methods, and optimal plastic vessels with low inherent variations of results. 2) PTS are well tolerable to up to 6 days of ex vivo culture 3) Choosing optimal time points for each of the drugs ensures more accurate representation of their drug activities. For example, epigenetic inhibitors have tendency to show better results on day 6 rather than day 3. 4) Multicolor flow cytometry provides previously unseen differences in drug activity profiles upon different clusters, which had not been visible from bulk-grade sensitivity profiling, such as colorimetric viability assay. Those specimens were genetically profiled by whole genome/ exome sequencing, as well as other multi-omics analyses (Bulk RNA seq, methylome analysis, and scRNA seq). 5) Optimizations of ex vivo culture methods not only ensure our better quality of these 6-day drug effects, but also extend the possibility of PTS for further applications by allowing leukemia stem cell fractions to be maintained in vitro for longer periods of time. They include long-term culture and ex vivo expansion of leukemic stem cells using the most updated serum-free liquid culture, and further gene modifications using various vectors. Collectively, our platform for DSS confers next-generation use of primary patient-derived biomaterials so that even a small- to middle-sized group can conduct these complexed assays to test their hypotheses based on primary specimens, which had been possible only in high-volume multi-institutional alliances.

Biomarker Study for Selecting Neoadjuvant Chemotherapy Regimens Based on Prognostic Prediction Using Gastric Cancer Biopsy Specimens from a Phase II Randomized Controlled Trial.

The randomized phase II COMPASS trial revealed that neither the regimen nor the number of courses of preoperative neoadjuvant chemotherapy (NAC) for locally advanced gastric cancer (GC) significantly influence overall survival (OS). However, the impact of NAC regimens on OS may vary from patient to patient. The aim of this study was to identify biomarkers that can predict more appropriate individualized NAC regimens for improved prognosis using biopsy specimens from the COMPASS trial. RNA was extracted from endoscopic biopsy specimens of primary tumors obtained prior to NAC and real-time PCR analysis of 127 genes was conducted to identify those significantly affecting survival in the context of specific NAC regimens. THBS1, MSI1, and IGF2BP3 were identified as significant factors for stratifying survival among different NAC regimens, with statistically significantly interaction p values. Immunohistochemical analysis confirmed that the protein levels of THBS1, MSI1, and IGF2BP3 strongly correlated with their gene expression levels, validating these proteins as reliable biomarkers. This study effectively identified THBS1, MSI1, and IGF2BP3 as promising biomarkers for personalizing NAC regimens in patients with locally advanced GC. By tailoring NAC based on these biomarkers, it is possible to enhance survival outcomes and advance personalized treatment strategies. The findings underscore the potential for incorporating biomarker-guided approaches into clinical trials, aiming to refine and optimize NAC regimens for improved patient-specific treatment efficacy.

Distribution characteristics of immune infiltration and lymphovascular invasion in patients with breast cancer skin recurrence

BackgroundTo assess the distribution characteristics of immune infiltration and lymphovascular invasion in breast cancer skin recurrence patients.MethodsWe retrospectively analyzed the clinicopathological data of patients who underwent radical surgery for primary breast cancer and experienced skin recurrence between January 2001 and April 2019. Immune and lymphovascular biomarkers were quantified in primary breast cancers, skin lesions and visceral metastatic lesions. Differences in biomarkers distribution between matched tissues were statistically analyzed using the Wilcoxon signed-rank test and Kruskal–Wallis one-way ANOVA.ResultsA total of 71 female breast cancer patients were reviewed in this study. Our study found that the expression levels of various lymphocyte immune markers in primary tumor specimens were higher than those in skin recurrences. The expression of CD8, CD57 and CD31 in primary breast cancer was higher than those in the skin. Compared to visceral metastatic lesions, D2-40 was highly expressed in the skin, while CD8 tended to decrease. In the skin specimens, the expression of CD8 (P < 0.001), FOXP3 (P = 0.006) and CD68 (P < 0.001) in the intratumoral area was higher, while the expression of CD57 (P < 0.001) was higher in the peritumoral area. Analyzing specimens from the same patient at different time points of skin progression, it was found that the expression of peritumoral CD4 decreased (P = 0.044) as the disease progressed. The low expression of D2-40 and CD163 in the skin lesions suggested a decrease in DFS.ConclusionThe immune microenvironment of breast cancer skin recurrence may be in a state of suppression, and this suppression may intensify with disease progression. The pattern of skin recurrence may be more inclined toward lymphatic invasion. Our study provides new insights into the biological behaviors of this disease and its response to immunotherapy.

Claudin-1 in head and neck squamous cell carcinoma

Introduction. The objective response rate to immunotherapy is limited in recurrent/metastatic head and neck squamous cell carcinoma (HNSCC) patients, whose prognosis is still dismal. Few prognostic factors are clinically available, mostly related to patient or disease characteristics. Gene expression signatures offer better prognostic abilities but are mainly used in research. One such GE model classifies HNSCC into 6 clusters with different prognoses. Claudin-1 (CLDN1), which influences tumor microenvironment and immune cell infiltration, has emerged as a potential target, especially in cancers like HNSCC with high CLDN1 expression. Methods. A single-center cohort of 100 loco-regionally advanced HNSCC patients from the BD2Decide observational study was analyzed. Patients were selected to balance long-term survivors and deceased patients, including HPV-negative and HPV-positive cases. Primary tumor specimens underwent GE analysis using Affymetrix ClariomD chips. Primary endpoint was overall survival (OS). Results. The cohort comprised 100 HNSCC patients with a median age of 60 years, predominantly men (76%). Median OS and DFS were 94.24 and 42.79 months, respectively. CLDN1 expression varied significantly among primary sites, being highest in hypopharynx cancers. Differences in expression were not significant when stratified by HPV status or clinical stage. CLDN1 expression differed across the 6 transcriptomic clusters, with the highest levels in clusters associated with mesenchymal and hypoxic features. Higher CLDN1 expression correlated with shorter OS (HR 3, p=0.0023) and DFS (HR 2.14, p=0.02). Conclusion. CLDN1 expression is heterogeneous in HNSCC and carries prognostic significance. It is highest in tumors with HPV-like biology and hypoxic environments, and lowest in immune-sensitive clusters. High CLDN1 is a negative prognostic factor and a promising therapeutic target. Anti-CLDN1 treatments could improve outcomes of CLDN1+ HNSCC patients, and combination therapies with ICIs might overcome resistance in CLDN1- cases. These findings support the need for clinical studies on anti-CLDN1 therapies.

Biphasic co-detection of melanoma aneuploid tumor cells and tumor endothelial cells in guidance of specifying the field cancerized surgical excision margin and administering immunotherapy

An optimum safety excision margin (EM) delineated by precise demarcation of field cancerization along with reliable biomarkers that enable predicting and timely evaluating patients’ response to immunotherapy significantly impact effective management of melanoma. In this study, optimized biphasic “immunofluorescence staining integrated with fluorescence insitu hybridization” (iFISH) was conducted along the diagnosis-metastasis-treatment-cellular MRD axis to longitudinally co-detect a full spectrum of intact CD31− aneuploid tumor cells (TCs), CD31+ aneuploid tumor endothelial cells (TECs), viable and necrotic circulating TCs (CTCs) and circulating TECs (CTECs) expressing PD-L1, Ki67, p16 and Vimentin in unsliced specimens of the resected primary tumor, EM, dissected sentinel lymph nodes (SLNs) and peripheral blood in an early-stage melanoma patient. Numerous PD-L1+ aneuploid TCs and TECs were detected at the conventional safety EM (2 cm), quantitatively indicating the existence of a field cancerized EM for the first time. Contrary to highly heterogeneous PD-L1 expression and degrees of Chr8 aneuploidy in TCs and TECs in the primary lesions as well as CTCs and CTECs in peripheral blood, almost all TCs and TECs in SLNs and EM were homogeneously PD-L1+ haploid cells. Dynamic monitoring and cellular MRD assessment revealed that, in contrast to PD-L1+ CTCs being responsive to the immune checkpoint inhibitor (ICI-anti-PD-1), multiploid (≥pentasomy 8) PD-L1+ and Ki67+ CTECs were respectively resistant to ICI-sensitized T cells. In therapeutically stressed lymphatic and hematogenous metastatic cascades, stratified phenotypic and karyotypic profiling of iFISH tissue and liquid biopsied TCs, TECs, CTCs and CTECs in future large-cohort studies will enable appropriate re-specification of the optimal safety EM and distribution mapping of in-depth characterized, subcategorized target cells to help illustrate their metastatic relevance, ultimately improving risk stratification and clinical intervention of tumor progression, metastases, therapy resistance and cancer relapse.

MDB-19. THE 3D CHROMATIN LANDSCAPE OF MEDULLOBLASTOMA

Abstract BACKGROUND Medulloblastoma (MB) is a highly malignant childhood cerebellar tumor comprised of four molecularly and clinically distinct subgroups. Sporadic yet subgroup-specific genetic and epigenetic landscapes suggest that higher-order chromatin topology may contribute to distinct subgroup identities and disease biology. Herein, we investigated the 3D chromatin landscape of MB by performing genome-wide chromosome conformation capture (Hi-C) across molecular subgroups using a cohort of n=24 patient-derived xenografts and primary tumor specimens, aiming to elucidate regulatory mechanisms facilitated by genome organization. METHODS Integrative analyses were adapted to incorporate a wide variety of sample-paired datasets. Chromatin contact matrices generated from Hi-C allowed for the mapping of active/inactive compartments (A/B compartments), topologically associated domains (TADs), and distal pairwise chromatin contacts (loops). Topological insights of chromatin architecture were complemented with whole-genome sequencing, RNA-seq, ATAC-seq, DNA methylation, CTCF and histone modification (H3K27ac/H3K27me3) ChIP-seq datasets to dissect mechanisms of gene regulation. RESULTS Unsupervised analysis revealed that chromatin compartmentalization is subgroup stratified. Gene loci contained in subgroup-unique active compartments correspondingly exhibited subgroup-specific chromatin contact patterns, adopted open chromatin conformations, and remained transcriptionally active. As an example, LIN28B resides within a Group 3-specific ‘A’ compartment where its local topology displays higher complexity compared to that of other subgroups. This consequentially facilitates a Group 3-unique loop connecting the LIN28B promoter with a distal enhancer, resulting in subgroup-specific transcriptional upregulation. Targeted displacement of CTCF that anchors and stabilizes chromatin looping at the LIN28B locus was sufficient to alter its transcriptional activity. Using similar lines of investigation, mechanistic insights into the topological determinants of known enhancer-hijacking events, including GFI1, GFI1B and PRDM6, were resolved. CONCLUSIONS Pioneering this integrative approach centered on comprehensive Hi-C maps, our study provides a high-resolution blueprint of the 3D chromatin landscape defining MB subgroups, informing the mechanistic basis of recurrent driver gene activation, and disclosing putative subgroup-specific vulnerabilities.

GCT-22. MEDICAL AND SURGICAL VARIABLES ASSOCIATED WITH RELAPSE IN CENTRAL NERVOUS SYSTEM (CNS) NONGERMINOMATOUS GERM CELL TUMORS (NGGCTS): SECONDARY ANALYSIS OF STRATUM 1 OF THE CHILDREN’S ONCOLOGY GROUP ACNS1123 PHASE 2 CLINICAL TRIAL

Abstract BACKGROUND ACNS1123 was a Phase 2 trial that evaluated the survival benefit of whole ventricular irradiation (WVI) instead of craniospinal irradiation in children with localized CNS NGGCTs who achieved a complete/partial radiographic response (CR/PR) to induction chemotherapy with negative tumor markers (beta-HCG/AFP) in serum and cerebrospinal fluid (CSF). Patients who did not achieve a CR/PR were considered inevaluable and removed from study therapy post-induction. METHODS In unplanned, exploratory analyses, we evaluated the association of age &amp;lt;15/&amp;gt;15-years at diagnosis, tumor location (pineal/suprasellar/bifocal/ventricular), tumor markers (beta-HCG/AFP) in serum and cerebrospinal fluid (CSF) at baseline (&amp;gt;/&amp;lt;1000), and rate of decline during induction in CR/PR and &amp;lt;CR/PR patients. Since most evaluable patients with relapse experienced distant failure in the spine, we assessed the impact of surgical variables, such as endoscopic third ventriculostomy (ETV)/biopsy/resection/combination, on spinal relapse in patients with or without disease progression. RESULTS 66 of 107 eligible patients achieved CR/PR with negative tumor markers while 41 patients did not. Bifocal tumors appeared to demonstrate a higher hazard for disease progression compared to suprasellar tumors (Hazard Ratio=5.4; p=0.0279). Otherwise, we did not find an association with progression-free-survival for any of the analyzed medical variables. Of 66 evaluable patients who received WVI, eight patients experienced relapse, with all patients demonstrating disease in the spine. No significant association was detected between any surgical variable (ETV/biopsy/resection) and spinal failure among evaluable patients who did or did not relapse; however, we had very limited power for these analyses due to very few events. CONCLUSION Current reliance on conventional parameters appears inadequate to identify biomarkers of response as well as relapse. Innovative approaches such as comprehensive genomic profiling of primary and recurrence tumor specimens could inform somatic clonal evolution and potential targeted therapies.

MYC and HSF1 Cooperate to Drive PLK1 inhibitor Sensitivity in High Grade Serous Ovarian Cancer.

Ovarian cancer is a deadly female cancer with high rates of recurrence. The primary treatment strategy for patients is platinum-based therapy regimens that almost universally develop resistance. Consequently, new therapeutic avenues are needed to overcome the plateau that current therapies have on patient outcomes. We describe a gene amplification involving both HSF1 and MYC, wherein these two genes on chromosome 8q are co-amplified in over 7% of human tumors that is enriched to over 30% of patients with ovarian cancer. We further found that HSF1 and MYC transcriptional activity is correlated in human tumors and ovarian cancer cell lines, suggesting they may cooperate in ovarian cancer cells. CUT&RUN for HSF1 and MYC in co-amplified ovarian cancer cells revealed that HSF1 and MYC have overlapping binding at a substantial number of locations throughout the genome where their binding peaks are near identical. Consistent with these data, a protein-protein interaction between HSF1 and MYC was detected in ovarian cancer cells, implying these two transcription factors have a molecular cooperation. Further supporting their cooperation, growth of HSF1-MYC co-amplified ovarian cancer cells were found to be dependent on both HSF1 and MYC. In an attempt to identify a therapeutic target that could take advantage of this dependency on both HSF1 and MYC, PLK1 was identified as being correlated with HSF1 and MYC in primary human tumor specimens, consistent with a previously established effect of PLK1 on HSF1 and MYC protein levels. Targeting PLK1 with the compound volasertib (BI-6727) revealed a greater than 200-fold increased potency of volasertib in HSF1-MYC co-amplified ovarian cancer cells compared to ovarian cancer cells wild-type HSF1 and MYC copy number, which extended to several growth assays, including spheroid growth. Volasertib, and other PLK1 inhibitors, have not shown great success in clinical trials and this study suggests that targeting PLK1 may be viable in a precision medicine approach using HSF1-MYC co-amplification as a biomarker for response.

EFFECT-neo: A phase 3 study of pembrolizumab plus chemotherapy versus chemotherapy as neoadjuvant therapy in patients with resectable locally advanced head and neck squamous cell carcinoma.

TPS6123 Background: There is still a huge need for treatment of operable locally advanced head and neck squamous cell carcinoma (LA HNSCC). Multiple phase 2 studies have shown that PD-1 combined with chemotherapy has good short-term efficacy, especially the pathological complete response (pCR) rate exceeds 30%, which is also considered to be an important factor in the survival benefit that neoadjuvant immune therapy may bring. The randomized, open-label, phase 3 EFFECT-neo study (NCT06102395) will evaluate efficacy and safety of pembrolizumab plus chemotherapy versus chemotherapy as neoadjuvant therapy in patients with resectable LA HNSCC. Methods: Patients with untreated LA HNSCC who met the inclusion criteria will be randomly assigned 1:1 to two treatment arms. Experimental group will be given 2 cycles of pembrolizumab (200mg d1, Q3W) + chemotherapy (perfer TPF regimens) . Control group will undergo 2 cycles of chemotherapy. Both two arms should finish imaging evaluation, and If the result is CR after neoadjuvant treatment, radiotherapy (RT) (60-70Gy) ± chemotherapy (investigator's choice) will be given as adjuvant treatment; if the result are PR or SD, surgery (within 2 weeks) will be performed, and then RT ± chemotherapy will be given. If the imaging evaluation is PD, patients will be received standard treatment. Enrolled patients must closely monitor the adverse reactions of chemotherapy and record the time, grade, treatment measures, outcomes, etc. All patients will be reviewed every 3 months for 1 year; after 1 year, they were reviewed every 6 months for 3 years; patient recurrence and survival data were recorded. Eligibility criteria will include age ≥18 years; untreated with immunotherapy, resectable, stage III/IVB HNSCC (AJCC Cancer Staging Manual, 8th edition); ECOG performance status 0-2; and the investigators believe that patients can safely receive pembrolizumab combined with chemotherapy in neoadjuvant chemotherapy. Randomization treatment will continue until disease progression, unacceptable toxicity, or decision to withdraw. Primary end points is pCR, defined as the absence of residual invasive squamous cell carcinoma within the primary tumor specimen on resection/needle biopsy (Patients with CR imaging results will undergo multi-point biopsy). Secondary end points include objective response rate, 1-year and 2-year event-free survival rates, 2-year overall survival rate, functional preservation rate, safety and Karnofsky performance status. Recruitment is ongoing and will continue until 272 patients are enrolled. Clinical trial information: NCT06102395 .

Neoadjuvant immunotherapy for oropharynx cancer: Correlative studies and long-term outcomes from the CIAO trial.

6059 Background: CIAO (Checkpoint Inhibitors Assessment in Oropharynx cancer) was a window of opportunity trial evaluating the anti-PD-L1 durvalumab (durva) with or without the anti-CTLA-4 tremelimumab (treme) prior to surgery in 28 oropharynx squamous cell carcinoma (OPC) patients (pts). Here we report correlative analyses and long-term survival outcomes. Methods: A total of 28 OPC pts were randomized to receive durva (n=14) or durva plus treme (n=14) for 2 cycles prior to surgery. Adjuvant radiotherapy with or without concomitant chemotherapy was recommended based on pathology findings, per standard of care. Efficacy and safety results have been previously reported. Whole exome sequencing (WES), RNA sequencing (seq), and TCR-seq were performed on available pre- and post-treatment primary tumor specimens. Circulating HPV was quantified pre-treatment and longitudinally. Associations with objective response (OR) to therapy per RECIST were determined using either Fisher’s exact test (binary variables) or rank-sum test (continuous variables). Multiple comparisons were corrected for by the Benjamini and Hochberg method. Disease-free survival (DFS) was defined as the time from surgery to recurrence or death. Results: Of the 28 enrolled pts, 20 were newly diagnosed and 8 had locoregional recurrent disease; 25 were HPV-positive. The OR rate per RECIST was 43%. Efficacy was equivalent in both arms. Responders tended to be of younger age (p=0.02). At the DNA level, baseline tumor mutation burden was not associated with response, but mutational contraction post-treatment was more often observed among responders (p=0.02). There were no statistically significant differentially expressed genes between responders and non-responders, however, immune deconvolution revealed that a low inferred tumor neutrophil-to-leukocyte ratio was associated with response (p=0.01). TCR-seq revealed 8 TCR motifs enriched in responders at 25% false discovery rate. Serum HPV levels significantly decreased in responders after treatment (p=0.02). With a median follow-up from surgery of 59.6 months (range 14.9-71.5 months; data cut-off 1/19/24), none of the 20 patients with newly diagnosed OPC had recurrence and all remain alive at the last contact date (DFS=100%). Of the 9 patients with recurrent OPC, 3 had subsequent distant recurrence and died of disease (median DFS=5.7 years, overall DFS=66.7%). Conclusions: Responses to neoadjuvant checkpoint inhibitors was associated with tumor mutational contraction and a low baseline neutrophil-to-leukocyte ratio in OPC. Eight TCR motifs were enriched in responders. Serum HPV level dynamics was associated with tumor burden and may be useful in response monitoring. DFS outcomes were favorable in both newly diagnosed and recurrent cohorts.

Proteogenomic characterization of difficult-to-treat breast cancer with tumor cells enriched through laser microdissection

BackgroundBreast cancer (BC) is the most commonly diagnosed cancer and the leading cause of cancer death among women globally. Despite advances, there is considerable variation in clinical outcomes for patients with non-luminal A tumors, classified as difficult-to-treat breast cancers (DTBC). This study aims to delineate the proteogenomic landscape of DTBC tumors compared to luminal A (LumA) tumors.MethodsWe retrospectively collected a total of 117 untreated primary breast tumor specimens, focusing on DTBC subtypes. Breast tumors were processed by laser microdissection (LMD) to enrich tumor cells. DNA, RNA, and protein were simultaneously extracted from each tumor preparation, followed by whole genome sequencing, paired-end RNA sequencing, global proteomics and phosphoproteomics. Differential feature analysis, pathway analysis and survival analysis were performed to better understand DTBC and investigate biomarkers.ResultsWe observed distinct variations in gene mutations, structural variations, and chromosomal alterations between DTBC and LumA breast tumors. DTBC tumors predominantly had more mutations in TP53, PLXNB3, Zinc finger genes, and fewer mutations in SDC2, CDH1, PIK3CA, SVIL, and PTEN. Notably, Cytoband 1q21, which contains numerous cell proliferation-related genes, was significantly amplified in the DTBC tumors. LMD successfully minimized stromal components and increased RNA–protein concordance, as evidenced by stromal score comparisons and proteomic analysis. Distinct DTBC and LumA-enriched clusters were observed by proteomic and phosphoproteomic clustering analysis, some with survival differences. Phosphoproteomics identified two distinct phosphoproteomic profiles for high relapse-risk and low relapse-risk basal-like tumors, involving several genes known to be associated with breast cancer oncogenesis and progression, including KIAA1522, DCK, FOXO3, MYO9B, ARID1A, EPRS, ZC3HAV1, and RBM14. Lastly, an integrated pathway analysis of multi-omics data highlighted a robust enrichment of proliferation pathways in DTBC tumors.ConclusionsThis study provides an integrated proteogenomic characterization of DTBC vs LumA with tumor cells enriched through laser microdissection. We identified many common features of DTBC tumors and the phosphopeptides that could serve as potential biomarkers for high/low relapse-risk basal-like BC and possibly guide treatment selections.

Abstract PO3-19-06: MRD Assay evaluates Recurrence and response via a tumor Informed Assessment: MARIA-Breast Observational Trial

Abstract Background: Detectable ctDNA in patients with solid tumors has been associated with disease prognosis pre-treatment, assessing response to therapy in the form of minimal residual disease (MRD), and monitoring for recurrence after curative intent treatment. Utilizing patient-specific genomic mutation profiling of an individual’s cancer from a tissue sample, in conjunction with the patient’s germline DNA, to create a personalized sequencing panel to analyze for a subset of these genetic mutations from ctDNA in blood is a strategy that has high sensitivity for detecting MRD. Studies have shown that pretreatment levels of ctDNA using this approach are a potential early indicator of disease recurrence after surgery, that ctDNA clearance may be an early predictor of favorable outcomes and has been shown to correlate with pathologic complete response (Forde et al. N Engl J Med. 2022, PMID:35403841), and that this approach has high sensitivity for detecting recurrence for patients in advance of the current standard of care (Abbosh et al. Cancer Res (2020) 80 (16_Supplement): CT023). Methods: This is a multi-site, prospective, observational trial in the United States of 200 patients with early stage breast cancer using a patient-specific tumor-informed MRD assay for ctDNA analysis. Participants are asked to provide study specimens prior to initial treatment intervention, after curative intent surgical resection, during adjuvant therapy (as applicable) and pre-recurrence follow-up. ctDNA will be analyzed with an NGS-based, tumor-informed MRD assay that identifies somatic mutations from DNA obtained from the patient’s tumor tissue, subtracts germline variants via NGS-based analysis of the patient’s germline DNA, and detects a selected set of between 18-50 tumor-specific ctDNA in their blood. All primary tumor specimens will undergo full exome sequencing using the Personalized Cancer Monitoring (PCM) assay. Impact of results of this CLIA-approved MRD assay on clinical decision making will be captured. The primary objective is to assess the ability of MRD to predict post-treatment recurrence. Further objectives are to correlate MRD status with pathologic complete response, determine the lead time to detection of recurrence compared to standard of care, and the association of MRD status with overall survival. Active enrollment started in March, 2022. Support: Invitae. Clinical trial information: NCT05219734. Citation Format: Edward Esplin, Kelli Swan, Lee Ifhar, Brandie Heald, Sarah Nielsen, Daniel Pineda-Alvarez, William O'Callaghan, Robert Daber, Darrel Ross, Carlos Vieira, Aadel Chaudhuri, W. Korn. MRD Assay evaluates Recurrence and response via a tumor Informed Assessment: MARIA-Breast Observational Trial [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO3-19-06.

Abstract PO2-16-04: Proteogenomic characterization of non-luminal A versus luminal A breast cancer tumor cells enriched by laser microdissection

Abstract Introduction: Breast cancer (BC) is classified into four widely-accepted intrinsic subtypes based on PAM (Prediction Analysis of Microarray) 50 gene expression profiles: Luminal A (LumA), Luminal B (LumB), Her2-enriched (Her2) and basal-like (Basal). Recent multi-omic studies of human BC have identified many potential therapeutic biomarkers for these subtypes and have also revealed the extensive molecular heterogeneity of the disease. Patients with LumA tumors generally have better outcomes because these tumors are typically slower-growing and responsive to hormone therapy. However, there is still considerable variation in the clinical outcomes of patients with non-LumA tumors. Here, we strive to understand the proteogenomic characteristics of intrinsically-defined non-LumA tumors in reference to LumA tumors. Methods: A total of 117 retrospectively-collected, untreated primary breast tumor specimens, with a focus on non-LumA subtypes, were selected from the Clinical Breast Care Project and consented using a HIPAA-compliant, IRB-approved protocol. The study cohort had a median patient follow-up of 9.3 years, enabling clinical outcome-related analyses. Immunohistochemistry (IHC) subtyping was used to enrich the cohort with non-LumA subtypes. Breast tumors were embedded in OCT (Optimal Cutting Temperature) compound and processed by laser microdissection (LMD) to enrich for tumor cells. DNA, RNA, and protein were simultaneously extracted from each tumor using the illustra triplePrep kit. Paired-end RNA sequencing and whole genome sequencing (WGS) were performed for 117 and 99 tumors, respectively, using the Illumina HiSeq platform. Quantitative global proteomics and phosphoproteomic analyses were performed on 112 and 50 tumors, respectively, using isobaric TMT 6-plex labeling with the “universal reference” strategy. Results: We observed significantly lower stromal, immune and microenvironment scores in non-basal-like tumors, especially the LumA subtype from LMD-processed samples, compared to that of the same tumors but bulk-processed in TCGA-breast cancer study. There was also significantly lower stromal gene expression in LMD LumA compared to TCGA LumA. Unlike a recent report on proteomics clustering of bulk-processed tumors, we did not observe a stromal-enriched cluster, probably because the use of LMD minimized stromal components. Many common patterns of somatic mutations were observed among non-LumA tumors, such as dominant TP53 mutations and 5q deletion, suggesting a potentially common cell-of-origin for non-LumA tumors, such as an ER negative cancer stem cell or progenitor cell for these tumor subtypes. Cell proliferation-associated genes were amplified and proliferation pathways strongly enriched in non-LumA tumors. In addition to this, we identified two distinct phosphoproteomic profiles for relapsed and relapse-free basal-like BC. Moreover, we also identified 17 differentially expressed phosphopeptides that could identify cases of relapsed and relapse-free basal-like BC with a significant difference in progression-free interval of surviving cases. Conclusion: This study provides an integrated proteogenomic characterization of non-LumA vs LumA tumor specimens enriched for cancer cells. We identified many common features of non-LumA tumors and also identified phosphopeptides that could serve as potential biomarkers for less aggressive basal-like BC and possibly guide treatment selections. Disclaimer: The contents of this publication are the sole responsibility of the author(s) and do not necessarily reflect the views, opinions or policies of USUHS, HJF, the DoD or the Departments of the Army, Navy or Air Force or the DOE or PNNL. Mention of trade names, commercial products, or organizations does not imply endorsement by the U.S. Government. Citation Format: Praveen Kumar Raj Kumar, Xiaoying Lin, Tao Liu, Lori Sturtz, Marina Gritsenko, Vladislav Petyuk, Tyler Sagendorf, Brenda Deyarmin, Jianfang Liu, Anupama Praveen-Kumar, Guisong Wang, Jason McDermott, Anil Shukla, Ronald Moore, Matthew Monroe, Bobbie-Jo Webb-Robertson, Jeffrey Hooke, Leigh Fantacone-Campbell, Brad Mostoller, Leonid Kvecher, Jennifer Kane, Jennifer Melley, Stella Somiari, Patrick Soon-Shiong, Richard Smith, Richard Mural, Karin Rodland, Craig Shriver, Albert Kovatich, Hai Hu. Proteogenomic characterization of non-luminal A versus luminal A breast cancer tumor cells enriched by laser microdissection [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO2-16-04.

DNA variants detected in primary and metastatic lung adenocarcinoma: a case report and review of the literature.

Non-small cell lung cancer (NSCLC) has been found to have recurrent genetic abnormalities, and novel therapies targeting these aberrations have improved patient survival. In this study, specimens from benign tissue, primary tumors, and brain metastases were obtained at autopsy from a 55-year-old White female patient diagnosed with NSCLC and were examined using next-generation sequencing (NGS) and chromosomal microarray assay (CMA). No genetic aberrations were noted in the benign tissue; however, NGS identified a mutation in the KRAS proto-oncogene, GTPase (KRAS): KRAS exon 2 p.G12D in primary and metastatic tumor specimens. We observed 7 DNA copy number aberrations (CNAs) in primary and metastatic tumor specimens; an additional 7 CNAs were exclusively detected in the metastatic tumor specimens. These DNA alterations may be genetic drivers in the pathogenesis of the tumor specimen from our patient and may serve as biomarkers for the classification and prognosis of NSCLC.

Abstract 5516: Aberrant activation and perpetuation of lung wound response facilitates osteosarcoma metastasis

Abstract Introduction: The mechanisms that allow tumor cells to integrate with unfamiliar parenchymal cells within hostile distant tissues during metastatic colonization remain poorly defined. Nowhere are these mechanisms more important than in osteosarcoma-a pediatric bone tumor where metastases cause nearly all osteosarcoma related deaths and occur almost exclusively in the lung. The purpose of this study was to define the cellular and molecular events that facilitate osteosarcoma lung colonization to devise novel therapeutic strategies that prevent and treat metastasis. Experimental Approach: We generated experimental lung metastases using a panel of immunocompetent murine and human xenograft osteosarcoma models. A combination of immunohistochemistry, single cell RNA sequencing, and spatial transcriptomics were used to define the metastatic niche. Relevant findings were validated in human primary tumor, lung metastasis, and normal lung tissue specimens. Results: Disseminated osteosarcoma cells physically associate with alveolar epithelial cells and trigger changes in surrounding epithelial cells that are characteristic of the aberrant, non-resolving wound response seen in non-malignant lung diseases such as idiopathic pulmonary fibrosis (IPF). This process drives the accumulation of fibrotic epithelial cells and scar-associated macrophages confined within a dense fibronectin-based matrix. Anti-fibrotic tyrosine kinase inhibitors used to treat patients with IPF (nintedanib) prevent the observed fibrogenic changes and inhibit metastatic colonization. Epithelial-osteosarcoma paracrine signaling is dominated by an inflammatory cytokine milieu that facilitates this transition towards fibrosis. Blocking one of the dominant paracrine signals with a recombinant IL1 receptor antagonist (anakinra) has similar effects on both fibrosis and metastatic colonization. Conclusions: Our study demonstrates that tumor interactions with host stromal cells are critical for metastasis. Metastatic colonization requires transformation of the local lung microenvironment into a fibrotic, non-resolving, cytokine-rich, wound-like state that is both provoked and sustained by tumor-epithelial interactions. These insights have identified several potential therapeutic approaches to prevent metastatic colonization and treat established metastases. Citation Format: James Brandon Reinecke, Amy C. Gross, Maren Cam, Leyre Jimenez Garcia, Matthew V. Cannon, Ryan D. Roberts. Aberrant activation and perpetuation of lung wound response facilitates osteosarcoma metastasis [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 5516.

Abstract 2522: Predictive value of tumor mutational burden (TMB) in patients with metastatic microsatellite-stable (MSS) colorectal cancer (CRC) given first-line oxaliplatin-based chemotherapy and immune checkpoint blockade (ICB)

Abstract Purpose: Most CRC patients harbor primarily non-immunogenic MSS tumor. The randomized METIMMOX trial (NCT03388190) examined if patients with previously untreated, unresectable abdominal metastases from MSS-CRC may achieve therapeutic efficacy from short-course oxaliplatin-based chemotherapy (FLOX) and sequential ICB (nivolumab) repeatedly. Half of study patients assigned to this experimental treatment had significantly extended progression-free survival (PFS) while the other half had shortened PFS, compared to the control-group patients given standard FLOX chemotherapy with median PFS 9.3 months. Here we explored if somatic mutations (mut) unveiled by next-generation sequencing might provide insights into responsiveness to the METIMMOX regimen. Procedures: Patients had MSS-CRC with infradiaphragmatic metastases deemed unresectable and were eligible for first-line oxaliplatin-based therapy. They were randomly assigned to the control group of FLOX (oxaliplatin, 5-fluorouracil, folinic acid) Q2W or the experimental group of alternating 2 cycles each of FLOX Q2W and nivolumab Q2W, with prespecified break periods. Radiologic response assessment was done every 8 weeks with PFS as the primary endpoint. Diagnostic tumor biopsies and baseline metastasis biopsies were sequenced with the TruSight Oncology 500 assay. TMB was calculated using only coding, non-synonymous single-nucleotide variants and insertions/deletions with variant allele frequency ≥5% and sequencing depth ≥50 ×, applying the effective panel size as the megabases (Mb) denominator. Results: Sequencing data were acquired from 20 experimental-group patients with median PFS 7.9 months (minimum 2.0, maximum 41.6). Median TMB was 5.1 mut/Mb (minimum 0.8, maximum 11.8), concordant in patient-paired primary tumor and metastasis specimens. The TMB was associated with treatment outcome; the higher TMB, the better PFS with hazard ratio 0.83 (95% confidence interval (CI) 0.70-0.98; p = 0.026, Cox regression) for a PFS event with increasing TMB. TMB cut-off as low as 5.0 mut/Mb distinguished between patient groups (p = 0.007, log-rank test) with median PFS 34.9 months (95% CI 10.6-59.2; TMB&amp;gt;5, n = 10) and median PFS 4.6 months (95% CI 2.7-6.5; TMB≤5, n = 10). In the TMB&amp;gt;5 group, 8/10 were KRAS- or BRAF-mutant cases. In the TMB≤5 group, 9/10 metastasis specimens were RAS/BRAF-wildtype cases. Conclusions: TMB &amp;gt;5 mut/Mb was associated with tumor KRAS or BRAF driver mutation and remarkably long PFS in first-line treatment of patients with abdominal metastases from MSS-CRC with alternating short-course oxaliplatin-based chemotherapy and ICB. Citation Format: Anne Hansen Ree, Paula A. Bousquet, Hilde L. Nilsen, Torben Lüders, Shixiong Wang, Tina Visnovska, Diana L. Bordin, Eirik Høye, Hanne M. Hamre, Christian Kersten, Eva Hofsli, Marianne G. Guren, Halfdan Sorbye, Kjersti Flatmark, Sebastian Meltzer. Predictive value of tumor mutational burden (TMB) in patients with metastatic microsatellite-stable (MSS) colorectal cancer (CRC) given first-line oxaliplatin-based chemotherapy and immune checkpoint blockade (ICB) [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 2522.

Abstract 7623: Biomarker study to personalized neoadjuvant chemotherapy using preoperative gastric cancer specimens of biopsy from the COMPASS trial, a phase II randmazed controlled trial

Abstract Background and Aim: The results of COMPASS, a randomized phase II trial, suggest that preoperative adjuvant chemotherapy (NAC) regimen or course for locally advanced gastric cancer (GC) does not affect overall survival (OS). However, we hypothesized that some NAC regimens may be more effective for OS on a case-by-case basis. Furthermore, we searched for biomarkers, assuming that further improvement in the outcome of locally advanced GC could be expected if appropriate NAC regimens could be selected using biomarkers before treatment initiation. Materials and Methods: RNA was extracted from endoscopic biopsy specimens of primary tumors collected prior to NAC administration in COMPASS patients, and real-time polymerase chain reaction (PCR) of 127 genes was performed to identify genes with significant (P &amp;lt; 0.05) interaction P values for survival with each regimen and stratified OS with each regimen. Genes were identified and biomarkers were searched at the protein level using immunohistochemical analysis. Results: The THBS1, MSI1, and IGF2BP3 genes were identified as genes whose expression levels significantly (P &amp;lt; 0.05) stratified survival for each regimen and had significant (P &amp;lt; 0.05) interaction P values. Furthermore, a strong correlation was observed between each gene and THBS1, MSI1, and IGF2BP protein expression by immunohistochemical analysis, confirming that protein expression levels by immunohistochemical analysis are also useful as biomarkers. Conclusion: Using endoscopic biopsy specimens prior to NAC for locally advanced GC, biomarkers were identified to select NAC regimens over predicted OS. The results of this study may guide the conduct of clinical trials of individualized treatment of NAC using biomarkers. Citation Format: Takashi Oshima. Biomarker study to personalized neoadjuvant chemotherapy using preoperative gastric cancer specimens of biopsy from the COMPASS trial, a phase II randmazed controlled trial [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 7623.

Abstract 7047: Comparative analysis of transcriptomic and immunological profiles in treatment-naïve black and non-Hispanic White women with high-grade serous ovarian cancer

Abstract Background: Ovarian cancer is a highly lethal gynecological malignancy and high-grade serous histology (HGSOC) accounts for the majority of cases. Platinum-based chemotherapy is the primary treatment. Notably, Black women face the highest mortality-to-incidence ratio across all ethnic groups. This study investigated transcriptomic and immunological differences in tumors from Black compared to NHW women that might explain the poor clinical outcomes observed within this patient cohort. Methods: We collected primary tumor specimens from 36 Black and 31 treatment-naïve NHW patients. After RNA isolation, RNA sequencing (RNA-seq) identified differentially expressed transcripts and Enrichr performed pathway enrichment studies. To confirm the observed gene expression differences, we employed quantitative reverse transcription PCR (qRT-PCR), western blotting, and multiplex immunohistochemistry (mIHC). Additionally, we conducted cell proliferation, colony formation, and cell viability assays to functionally validate potential target genes of interest. Results: Our findings revealed 277 genes with significant differential expression between Black and NHW patients (FDR-adjusted p-value &amp;lt; 0.05). Among these, 103 coding genes were up-regulated, while 81 coding genes were down-regulated in tumors from Black compared to NHW patients. Gene Ontology analyses of these significantly differentially expressed genes highlighted enriched pathways related to DNA damage response, including the insulin receptor (INSR) gene, p53/apoptosis signaling components such as Forkhead box proteins A1 (FOXA1) and FOXB1, as well as genes involved in the cholesterol/lipid modulation pathway, including Low-density lipoprotein (LDL) receptor and Stearoyl-CoA Desaturase (SCD). Notably, silencing INSR and FOXA1 enhanced sensitivity to platinum-based drugs and inhibited cell growth and colony formation. Furthermore, we identified differences in the proportions of key immune cell types between the two patient groups, with tumors from Black patients exhibiting a significantly lower proportion of CD4+ Naïve T-cells and CD4+ regulatory T-cells (Tregs). Conclusions: Overall, our study reveals significant differential gene expression patterns between HGSOC tumors from Black and NHW patients, as well as differences in the proportions of immune cell types. These discoveries provide valuable insights into the biological mechanisms underlying the disparities in outcomes observed between black and NHW patients afflicted with HGSOC. It is critical to further investigate how these biological differences affect clinical outcomes and treatment response in Black women. Citation Format: Hao Huang, Russel Keathley, Ujin Kim Kim, Horacio Cardenas, Ping Xie, Jianjun Wei, Guangyuan Zhao, Emma L. Barber, Ernst Lengyel, Kenneth P. Nephew, Victoria Bae-Jump, Bin Zhang, Daniela Matei. Comparative analysis of transcriptomic and immunological profiles in treatment-naïve black and non-Hispanic White women with high-grade serous ovarian cancer [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 7047.

Abstract 2758: Stemness subtype gastric cancer accelerate hematogenous metastasis

Abstract Oncogenic progression and metastasis correlate with the acquisition of stem cell-like characteristics and the loss of differentiated phenotype. Poorly differentiated primary tumors often lead to unfavorable oncologic outcomes due to a heightened likelihood of metastasis to distant organs across various cancers. However, the relationship between stemness traits and metastasis in gastric cancer (GC) remains insufficiently explored. In this investigation, we analyzed bulk RNA-sequencing from microdissected primary tumor specimens and clinical data to pinpoint molecular subtypes linked to distant organ metastasis. Transcriptomic data from patient-derived xenograft (PDX) samples and available single-cell RNA datasets validated our bulk RNAseq findings. Comprehensive analysis highlighted the molecular traits of GC tied to hematogenous metastasis. Microdissection of primary tumor FFPE samples facilitated bulk RNA sequencing, encompassing samples from 33 metastatic and 31 metastasis-free patients, with 8 paired normal samples. Most samples contained less than 10% of tumor microenvironment (TME) components like fibroblasts, endothelial cells, and immune cells. Using non-negative matrix factorization (NMF) clustering, we achieved unsupervised subtyping of the gastric cancer gene expression matrix. Permutation tests based on subsampling indicated consistent high-level cophenetic coefficients at k=2, suggesting robust bifurcation of transcriptomic data into two clusters. One showed augmented stemness traits while the other emphasized differentiated mucosal genes, labeled as stemness and differentiated subtypes, respectively. GSEA highlighted a significant boost in the Hallmark angiogenesis score in the stemness subtype, not attributed to endothelial cell infiltration as verified by CIBERSORTx. This subtype also exhibited a marked decrease in hematogenous metastasis-free survival (HMFS) (p=0.008, log-rank test). Further, PDX samples were scrutinized. Post classification of the PDX graft expression matrix via logistic regression, we examined the endothelial cell fraction, determined by CIBERSORTx. Stemness subtype PDX grafts revealed a significant elevation in the host (mouse) endothelial cell fraction (p&amp;lt;0.05). In addition, stemness PDX patient showed significant decreased HMFS (p = 0.03). We also categorized the pseudobulk expression matrix of malignant cells into stemness or differentiated subtypes using GSE183904 scRNA cohort. scRNA sample analysis consistently presented an elevated endothelial cell fraction in the stemness GC subtype. The outcomes suggest a propensity for angiogenesis in the TME of the stemness subtype of GC. In conclusion, our findings demonstrate that the stemness subtype of GC accelerates hematogenous metastasis, as evidenced through clinical data, bulk RNAseq, PDX, and scRNAseq data. Citation Format: Seungho Lee, Jaeun Yoo, Seungbok Lee, Hyun Myong Kim, Kyoungyun Jeong, Yie-Ri Yoo, Ji-Yeon Shin, Kyoung Un Park, Hye Seung Lee, Seong-Ho Kong, Do Joong Park, Hyuk-Joon Lee, Han-Kwang Yang. Stemness subtype gastric cancer accelerate hematogenous metastasis [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 2758.

Abstract B032: Use of patient-derived organoids to model tumor evolution in response to chemotherapy

Abstract Serous endometrial and ovarian cancers represent significant morbidity and mortality for gynecologic cancers due to the high rate of resistance to chemotherapy and recurrence after treatment. Among the many reasons for poor outcomes is a lack of preclinical models that reflect the complex heterogeneity across patients. Our objective was to create patient-derived organoid (PDO) models of serous endometrial and ovarian cancer and examine how genomic profiles evolve in response to standard therapy. This study was performed in four PDO models of serous gynecologic cancer, including serous endometrial, high grade and low grade serous ovarian, and high grade serous fallopian tube. We first compared genomic alterations in the primary tumors and PDOs using a 484-gene NGS panel (NovoPM 2.0, Novogene). A large overlap in single nucleotide variants (SNVs), copy number variations (CNVs) and indels was observed between primary tumor tissue and the corresponding PDO model. For example, there was an average of 175 shared SNVs between each primary tumor and PDO model and &amp;lt;20 unique variants in the PDO that were not present in primary tumor specimen. For the patient with serous fallopian tube cancer, we were further able to generate PDO models from tumor tissue acquired from three different sites: ovary, omentum, and ascites fluid. We found that 217 SNVs were shared among the PDOs from the three sites, with only 2-11 variants unique to each location. Interestingly, eight unique CNVs were detected in the ovary and ascites PDOs but not in the metastatic (omentum) PDO. We next exposed each PDO to a short 3-day pulse of carboplatin+paclitaxel to create chemoexposed models. The rationale for this duration of exposure is that clinical response in patients has been shown to correlate with drug response at 72 hrs in PDO models of ovarian cancer. As expected, all chemoexposed PDOs were more resistant to chemotherapy as compared to treatment-naïve counterparts. Genomic analysis of the treatment-naïve vs. chemoexposed PDOs revealed acquisition of new variants, such as a p53 mutation in the serous endometrial model after the pulse of chemotherapy. Finally, we compared drug sensitivity of the treatment-naïve vs. chemoexposed PDOs to agents used in the adjuvant and recurrent settings. The chemoexposed models yielded different drug profiles, with some showing increased sensitivity and others increased resistance. Taken together, these data substantiate that PDO models retain tumor heterogeneity, exhibited by the different genomic profiles and varying chemosensitivity. In addition, PDO models can be used to model the genomic and drug response profiles that arise in response to chemotherapy. Citation Format: Andreea Newtson, Emily Symons, Paige Malmrose, Eric Devor, Samantha Parks, Craig Rush, Jessica Andrew-Udoh, Haley Losh, Jay Gertz, Kristina Thiel, Kimberly Leslie. Use of patient-derived organoids to model tumor evolution in response to chemotherapy [abstract]. In: Proceedings of the AACR Special Conference on Endometrial Cancer: Transforming Care through Science; 2023 Nov 16-18; Boston, Massachusetts. Philadelphia (PA): AACR; Clin Cancer Res 2024;30(5_Suppl):Abstract nr B032.