Assessment Of Tumor Burden Research Articles

A Rare Case of Orbital Metastasis from Invasive Lobular Carcinoma: Challenges of 18F-FDG PET/CT and the Search for Consensus on Imaging.

Invasive lobular carcinoma (ILC) frequently underlies orbital metastasis. A 74-y-old woman, who was current with mammograms and had no cancer history, presented to her ophthalmologist with visual complaints and was found to have metastatic ILC. MRI was contraindicated, and an 18F-FDG PET/CT scan revealed a mildly hypermetabolic right orbital mass and low uptake in the left subareolar breast, suggestive of metastatic ILC. Small studies have found that in ILC, 16α-18F-fluoroestradiol and fibroblast activation protein inhibitors are more avid than 18F-FDG. There is currently no consensus regarding imaging for ILC. Many people have contraindications to MRI, and the higher rate of false-negative findings on mammography for ILC than for other breast cancers makes this patient population more vulnerable to inaccurate staging, incorrect assessment of tumor burden, and, consequently, insufficient treatment. We provide this interesting case to highlight the potential of 18F-fluoroestradiol PET/CT and fibroblast activation protein inhibitors over 18F-FDG in this breast cancer subtype.

Imaging in malignant peritoneal neoplasms.

Peritoneal malignancies encompass a diverse range of tumors originating within the peritoneum, including primary tumors such as mesothelioma and primary serous peritoneal carcinoma or secondary tumors resulting from the spread of cancers from gastrointestinal, gynecological, and extra-abdominal sources. The traditional approach of palliative care for these malignancies is being replaced by a multimodal strategies that integrates surgery with systemic or intraperitoneal chemotherapy. Notably, cytoreductive surgery combined with hyperthermic intraperitoneal chemotherapy has shown significant improvements in survival rates. Imaging is crucial in the multidisciplinary management of these tumors, aiding in diagnosis, staging, restaging, and monitoring therapy response. It is also vital for appropriate patient selection, using the acronym "PAUSE", which involves assessing tumor burden via the peritoneal carcinomatosis index, evaluating patients pre- and post-therapy, detecting complications following therapy, and predicting treatment outcomes. This review explores the imaging manifestations of peritoneal malignancies, distinguishing them from various mimics, and underscores the importance of imaging modalities such as CT, MRI, PET/CT, and PET/MRI in effective decision-making and management.

Preoperative [18F]fluoro-PEG-folate PET/CT in advanced stage epithelial ovarian cancer: A safety and feasibility study

PurposeThe selection for either primary or interval cytoreductive surgery (CRS) in patients with epithelial ovarian cancer (EOC) is currently based on imaging techniques like computed tomography (CT), [18F]fluorodeoxyglucose-positron emission tomography ([18F]FDG-PET), diffusion-weighted magnetic resonance imaging (DW-MRI) and/or diagnostic laparoscopy, but these have limitations. Folate receptor (FR)-targeted PET/CT imaging, using [18F]fluoro-PEG-folate, could improve preoperative assessment, potentially reducing unnecessary laparotomies. This paper presents the first experience with [18F]fluoro-PEG-folate PET/CT imaging in advanced stage EOC, focusing on safety, tolerability, and feasibility for reflecting the extent of disease. MethodsTolerability and safety were monitored after administration of the [18F]fluoro-PEG-folate tracer by measurements of vital function parameters (blood pressure, heart rate, peripheral oxygen saturation, respiratory rate, and temperature). In addition, (serious) adverse events were recorded. Disease burden was quantified using the Peritoneal Cancer Index (PCI) score on preoperative [18F]fluoro-PEG-folate PET/CT and during surgery. PCI scores were compared with intraoperative findings, considering histopathologic results as the gold standard. Tissue specimens were stained for FRα and FRβ. Relative uptake of the radiotracer by EOC lesions and other tissues was quantified using body weighted standardized uptake values (SUV). ResultsThe study was terminated prematurely during the interim analysis after inclusion of eight patients of whom five had completed the study protocol. Although [18F]fluoro-PEG-folate demonstrated safety, efficacy for tumor-specific imaging was limited. Despite clear FRα overexpression, low tracer uptake was observed in EOC lesions, contrasting with high uptake in healthy tissues, posing challenges in specificity and accurately assessing tumor burden. ConclusionsOverall, while [18F]fluoro-PEG-folate was well-tolerated, its clinical utility in the preoperative assessment of the extent of disease in EOC was limited. This highlights the need for further research in developing targeted imaging agents for optimal detection of EOC metastases.Trial registration: Clinicaltrials.gov, NCT05215496. Registered 31 January 2022.

Early prediction of pancreatic cancer through detection of methylated circulating DNA in blood.

e16353 Background: Pancreatic cancer represents a significant oncological challenge, contributing markedly to cancer-associated mortalities. This is attributed to the asymptomatic nature of early-stage disease, its inherently aggressive phenotype, and a notably suboptimal response to existing systemic therapies. Hence, the formulation of efficacious early diagnostic modalities for pancreatic cancer amenable to surgical resection is imperative to augment patient prognoses and enhance survival outcomes. Methods: The Infinium MethylationEPIC v2.0 BeadChip platform facilitated the examination of methylation profiles within plasma samples, while the HumanMethylation450 BeadChip array was employed for analogous analyses in corresponding tissue specimens from Taiwanese pancreatic cancer cohorts, aiding in gene selection. Subsequent methylation status verification was conducted via quantitative Methylation-Specific PCR (qMSP) on both genomic DNA and circulating cell-free DNA samples. For external methylation confirmation within a Western demographic, data from The Cancer Genome Atlas (TCGA) Portal were utilized, with further validation conducted using plasma samples from U.S. pancreatic cancer patients. Total 105 plasma from pancreatic cancer patients and healthy subjects were analyzed to calculate the candidate the accuracy, sensitivity, specificity of biomarkers for predict the pancreatic cancer. Results: The test exhibited an accuracy of 90.4%, sensitivity of 92.3%, and specificity of 90.1% in the detection of pancreatic cancer. Detection levels increased from 0% in healthy individuals to 87.5% in Stage I and 100% in Stages II, III, and IV. The CA19-9 marker displayed limited specificity with a high rate of false positives. Moreover, the test dynamically evaluated tumor burden by monitoring circulating methylated ZFP30 and FBXL7 in the plasma of breast cancer patients post-treatment. Conclusions: The analysis of plasma for methylated ZFP30 and FBXL7 provides an innovative and accurate noninvasive method that outperforms the existing blood biomarker CA19-9 for the prediction and ongoing assessment of tumor burden following treatment in pancreatic cancer.

Plasma circulating tumor DNA in patients with cutaneous squamous cell carcinoma: Initial experience.

e15034 Background: Circulating tumor DNA (ctDNA) has emerged as a potential noninvasive biomarker to assess tumor burden throughout cancer treatment and to aid in clinical decision-making. However, data on the use of ctDNA in cutaneous squamous cell carcinoma (cSCC) is currently lacking. In this study, we report our first experience with ctDNA in patients with cSCC. Methods: In this IRB-approved study at a tertiary care center, an initial cohort of patients with intermediate to high-risk cSCC had tissue and plasma sent for ctDNA analysis using Natera®’s proprietary bioinformatics pipeline. This cohort included 21 patients treated from 2023 to the present. Initial tissue samples were obtained through biopsy (i.e., excisional, punch, or shave), Mohs surgery, or surgical resection. Some patients had additional plasma sample(s) drawn later during or after the treatment course. Patients either received a “positive,” “positive below analytical range,” or “negative” result or had ‘insufficient sample’ to receive a result based on Natera®’s analysis. All patients were treated curatively with surgical resection with or without adjuvant radiation as per the standard of care. The assessment of gross disease was determined based on whether the patient had disease present on imaging or physical exam at the time of the plasma draw. A comparison of ctDNA results and the presence of gross disease was done using Fisher’s exact test. Results: Of the samples submitted for Natera® ctDNA analysis, 18/21 had sufficient tissue for analysis of tumor DNA. All 3 tumors with insufficient tissue were from biopsies (6/9 sufficient), while 12/12 of those from Mohs or surgical resection had sufficient tissue. The average tumor volume in these patients with insufficient samples for tumor analysis was relatively low (0.35 cm3) compared to those that resulted (17-30 cm3). 7/9 (78%) patients with gross disease had a positive ctDNA result, which was significantly greater than those with no gross disease (1/9 patients, 11%) (p = 0.004). Three patients in our cohort with an initially positive ctDNA result had multiple plasma draws, with all having a later draw demonstrating a negative ctDNA result after having surgery and/or radiation. Conclusions: Circulating tumor DNA is a reliable marker for patients with cSCC with a high tumor burden and is feasible in those with adequate tissue. However, in patients where it is only possible to obtain a small volume of tumor tissue and/or low tumor burden, ctDNA may be a less reliable biomarker. [Table: see text]

Towards consistency in pediatric brain tumor measurements: Challenges, solutions, and the role of artificial intelligence-based segmentation.

MR imaging is central to the assessment of tumor burden and changes over time in neuro-oncology. Several response assessment guidelines have been set forth by the Response Assessment in Pediatric Neuro-Oncology (RAPNO) working groups in different tumor histologies; however, the visual delineation of tumor components using MRIs is not always straightforward, and complexities not currently addressed by these criteria can introduce inter- and intra-observer variability in manual assessments. Differentiation of non-enhancing tumors from peritumoral edema, mild enhancement from absence of enhancement, and various cystic components can be challenging; particularly given a lack of sufficient and uniform imaging protocols in clinical practice. Automated tumor segmentation with artificial intelligence (AI) may be able to provide more objective delineations, but rely on accurate and consistent training data created manually (ground truth). Herein, this paper reviews existing challenges and potential solutions to identifying and defining subregions of pediatric brain tumors (PBTs) that are not explicitly addressed by current guidelines. The goal is to assert the importance of defining and adopting criteria for addressing these challenges, as it will be critical to achieving standardized tumor measurements and reproducible response assessment in PBTs, ultimately leading to more precise outcome metrics and accurate comparisons among clinical studies.

Abstract PO2-15-02: Personalized circulating tumor DNA (ctDNA) monitoring can early identify disease progression and predict prognosis in patients with breast cancer undergoing neoadjuvant therapy

Abstract Background: Circulating tumor DNA (ctDNA) analysis offers a non-invasive method to assess tumor burden during treatment. Although some data have been reported on the use of ctDNA in neoadjuvant therapy (NAT) for breast cancer (BC), there is a lack of data on neoadjuvant efficacy and prognosis in China specifically using tumor-informed personalized ctDNA monitoring panel. Methods: We performed personalized ctDNA analyses at different time of NAT (before, during, and after) in 19 patients with Stage IIA-IIIB BC. WES was conducted on tumor tissues, and single nucleotide variants (SNVs) (20-40) were selected for each patient to ensure accurate and sensitive detection of individual ctDNA(Shanghai OrigiMed Co., Ltd.). Results: A total of 19 BC patients, 6 HER2-negative and 13 HER2-positive, were enrolled at the Breast Center, Fourth Hospital of Hebei Medical University (China) from June 2022 to May 2023. The median age of the patients was 53 (min-max: 28-64) years old. Through WES, it was discovered that 78.5% (3377/4303) of the mutated genes were unique to each patient. Additionally, 96.1% (637/663) of the selected tumor-informed SNVs were VUS variants. These findings suggest that tumor-informed ctDNA monitoring is more effective than panel-based ctDNA monitoring in BC. Among the patients, 84% (16/19) completed baseline blood collection, 63% (12/19) completed blood collection after NAT and 42% (8/12) patients completed blood collection after the surgery. The baseline positivity rate was 100%, and the baseline ctDNA variant allele frequency was significantly associated with T stage and N stage (both p < 0.01). This suggests that designing a panel based on puncture samples is feasible for ctDNA analysis. The detection of ctDNA before surgery after NAT correlated with the postoperative ctDNA status. Patients with persistently negative ctDNA during NAT were associated with pathologic complete response (pCR), although the difference was not statistically significant due to the small sample size (n=7). In 84% of patients, dynamic changes in ctDNA aligned with imaging findings, indicating a correlation between ctDNA and disease progression. A 56-year-old patient with HER2-negative stage IIIC BC had persistent ctDNA positivity during NAT. Imaging evaluation showed disease progression, with ctDNA allele frequency increasing 18 days before detection on imaging. After surgical tumor removal, the pathology assessment revealed a change in HER2 status from negative to positive. The patient received adjuvant chemotherapy combined with HER2-targeted therapy, resulting in a transition from positive to negative ctDNA status. The disease has remained stable for nearly 9 months. A 29-year-old patient with HER2-positive stage IIIA BC underwent NAT for 8 cycles. Due to drug intolerance, the treatment was interrupted multiple times during the first 4 cycles, and ctDNA remained positive. After modifying the treatment regimen in the 5th cycle, ctDNA became negative until the patient underwent surgery. The postoperative pathology evaluation revealed a pCR. Conclusions: Personalized ctDNA monitoring is more effective than panel-based ctDNA (a predefined set of cancer-associated genes) monitoring in BC. The status of ctDNA before and after surgery following NAT may be correlated, suggesting that patients with positive ctDNA before surgery may benefit from intensive therapy. More importantly, dynamic changes in ctDNA closely align with radiological findings, enabling early detection of disease progression and guiding treatment modifications. Citation Format: Yunjiang Liu, Chao Shi, Xiangmei Zhang, Xiaofei Ren, Shang Wu, Yaxian Wang, Yue Che, Zanmei Xu, Fei Pang. Personalized circulating tumor DNA (ctDNA) monitoring can early identify disease progression and predict prognosis in patients with breast cancer undergoing neoadjuvant therapy [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO2-15-02.

ВИЗУАЛИЗАЦИЯ ПЕРИТОНЕАЛЬНОГО МЕТАСТАЗИРОВАНИЯ: ОБЗОР ЛИТЕРАТУРЫ И СОБСТВЕННЫЙ ОПЫТ

Peritoneal metastasis is typical for malignant neoplasms of the ovary, stomach, intestines and other localizations. Metastases can mimic other pathological changes. Ambiguous conclusions about the effectiveness of certain methods of visualization and differentiation of peritoneal metastasis given in the scientific literature explain the lack of a unified approach in its diagnosis. Imaging of the peritoneum directly impacts tumor burden assessment, prognosis, and treatment planning. Purpose of the study: to analyze the information content of modern methods of visualizing peritoneal metastasis, based on literature data and our own experience. Materials and methods. The study was carried out on the basis of a literature analysis of publications of the electronic search system PubMed. We also conducted our own research on the comparative effectiveness of visualization methods implemented in the conditions of the Republican Clinical Oncologic Dispensary of Ministry of Health of the Republic of Bashkortostan. Results: analysis of the literature showed that all visualization methods have certain capabilities and limitations. Diagnosis of metastases located in the small intestine and lesions less than 5 mm in size is significantly difficult. Adhesive processes in the abdominal cavity, difficult to differentiate confluent tumor masses and inflammatory changes also affect the examination results. Our own experience demonstrates the admissibility of using a combination of pelvic magnetic resonance imaging and abdominal computed tomography for preoperative visualization of peritoneal metastases. Imaging results using instrumental methods were comparable to surgical assessment. In addition to the diagnostic limitations stated in the scientific literature, we identified difficulties in interpreting the results due to the lack of criteria for assessing peritoneal pathology by radiologists. Conclusion. Thus, according to the literature, the standard for diagnosing peritoneal metastases has not been defined. Computed tomography and magnetic resonance imaging methods are relatively accessible methods for visualizing peritoneal metastasis and complement each other, taking into account the diagnostic limitations and capabilities of each. To improve the assessment of the tumor burden at the preoperative stage, it is worth considering the possibility of creating uniform protocols for describing peritoneal metastases by abdominal region by radiologists, which will significantly facilitate the assessment and treatment planning in the future.

Abstract 440: BAP1 deubiquitinates ACLY to promote lipogenesis yet predisposing cholangiocarcinoma to iron overload and ferroptosis

Abstract Background: Cholangiocarcinoma (CCA) is a highly lethal and aggressive epithelial cell malignancy of the liver and biliary tract. CCA survival remains poor and response to chemotherapy or immunotherapy is limited. We AIM to identify metabolic vulnerabilities that render CCA susceptible to ferroptosis, an iron-dependent and caspase-independent cell death driven by lipid peroxidation. Materials and Methods: We treated human and mouse CCA cell lines with ferroptosis inducers (RSL3, Erastin), inhibitors (Fer-1, Lip-1), necroptosis inhibitor and a pan-caspase inhibitor. Cell viability, intracellular and mitochondrial iron, lipid peroxidation, mitochondrial structure, and function by cell-based and biochemical assays. Gain- and loss-of-function strategies, TURBO proximity-dependent biotin identification, and metabolic techniques were used for mechanistic studies. In vivo, orthotopically implanted C57B/6 mice were treated with RSL3 or vehicle intraperitoneally, followed by assessment of tumor burden and immunophenotyping analysis. Epcam-aptamer coated nanoparticles (tMNPs) packaged with siRNA against GPX4 were used for selective ferroptosis induction. Results: We identified ferroptosis-sensitive and -resistant human and mouse CCA cells. Ferroptosis-sensitive cells, rescued by ferroptosis inhibitors but not by necroptosis or pan-caspase inhibitors, exhibited elevated intracellular free iron and mitochondrial iron overload. This led to significant mitochondrial dysfunction and structural changes associated with ferroptosis. Mitochondrial free iron triggered reactive oxygen species generation and lipid peroxidation. We identified BRCA-associated protein 1 (BAP1) as a potential driver of ferroptosis sensitivity. BAP1, mutated in 22-25% of human CCAs, is a tumor suppressor and deubiquitinase (DUB). BAP1 knockdown by siRNA protected cells from ferroptosis, while re-expression of BAP1 sensitized cells to ferroptosis. Subcellular fractionation identified BAP1 in extranuclear compartments, including mitochondria and cytosol. We found that BAP1 interacts and deubiquitinates ATP citrate lyase (ACLY), which converts iron chelator citrate to oxaloacetate and acetyl-CoA. Inhibition of mitochondrial citrate export, protected cells from iron overload and ferroptosis. In vivo, RSL3-induced ferroptosis significantly reduced tumor burden, as compared to vehicle-treated mice. RSL3-induced ferroptosis promoted an immunogenic tumor immune microenvironment. Lastly, tMNPs with siGPX4 induced marked ferroptosis of mouse CCA cells and showed maximal enrichment in liver orthotopic tumors in vivo. Conclusions: Our findings indicate that BAP1 deubiquitination of ACLY predisposes CCA cells to iron overload by exhausting citrate to support lipogenesis. CCA vulnerability to ferroptosis opens up novel therapeutic opportunities for CCA. Citation Format: Peyton Classon, Sophia Jaramillo, Danielle Carlson, Irene Yan, Tushar Patel, Sumera I. Ilyas, Rory L. Smoot, Gregory J. Gores, Davide Povero. BAP1 deubiquitinates ACLY to promote lipogenesis yet predisposing cholangiocarcinoma to iron overload and ferroptosis [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 440.

Abstract 6557: Longitudinal cell-free tumor load dynamics represent an early endpoint for immunotherapy response in non-small cell lung cancer

Abstract Background: Liquid biopsies can inform treatment strategies by rapidly and accurately assessing tumor burden; with emerging data supporting the clinical utility of circulating cell-free tumor DNA (ctDNA) as an early endpoint of immunotherapy response. Methods: We performed targeted error-correction sequencing of ctDNA (n=330) and matched white blood cell (WBC) DNA (n=109) from 109 patients with advanced non-small cell lung cancer (NSCLC) who received immune checkpoint inhibitor monotherapy (n=79) or immunotherapy-containing combination regimens (n=30). Variant cellular origin was determined using a tumor-independent WBC DNA-informed approach. The maximum mutant allele fraction (maxMAF) of tumor-derived mutations was tracked longitudinally to assess changes in total cell-free tumor load (cfTL). Results: Among 3,418 variants with resolved cellular origin, 2,452 (72%) were tumor-derived, 125 (4%) were germline, while 841 (25%) were related to clonal haematopoiesis (CH). Cell-free DNA fragments harbouring tumor-derived mutations were significantly shorter than fragments containing wild-type alleles; however, fragment length alone was insufficient to distinguish CH variants from wild-type. Overall, 97 (89%) patients with >1 detectable tumor mutation were considered for cfTL tracking and molecular response assessment. Clearance of cfTL indicated molecular response (mR) whereas persistence indicated molecular progression (mPD). Time-course analyses, aiming to establish the optimal timing for molecular response assessment, revealed that early cfTL clearance within 3-9 weeks was significantly linked to improved survival outcomes. Notably, blood tumor mutation burden above or below 16 mutations/megabase showed no association with overall survival (OS; log rank p=0.98) or progression-free survival (PFS; log rank p=0.95). Of 81 patients evaluated for early on-therapy molecular responses, 28 (35%) were classified as having an mR, while 53 (65%) patients were classified in the mPD category. The median time to mR was 5 weeks in patients receiving immune checkpoint monotherapy and 6 weeks in patients receiving chemo-immunotherapy combination regimens. Patients in the mR group achieved longer OS (log rank p=0.001) and PFS (log rank p=0.0003) compared to those with mPD. Assessment of landmark PFS at 6 months demonstrated a significant association between ctDNA molecular response and durable clinical benefit (DCB) in patients receiving immune checkpoint monotherapy (p < 0.001, Fisher’s exact test), and a numerical association with DCB in patients on chemo-immunotherapy (p=0.07, Fisher’s exact test). Conclusions: Longitudinal tracking of ctDNA provides a real-time and accurate approach for monitoring immunotherapy response. These findings underscore the clinical utility of employing ctDNA molecular response to inform clinical decision-making. Citation Format: Lavanya Sivapalan, Bahar Alipanahi, Archana Balan, Jamie E. Medina, Noushin Niknafs, Erica Peters, Jaime Wehr, Alissa Konicki, Mimi Najjar, Bryan Chesnick, Gavin Pereira, Sarah Rongione, Nisha Rao, Michael Rongione, Brittany Shavatt, Lorenzo Rinaldi, Benjamin Levy, Victor E. Velculescu, Patrick M. Forde, Valsamo Anagnostou. Longitudinal cell-free tumor load dynamics represent an early endpoint for immunotherapy response in non-small cell lung 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 6557.

Abstract 4136: Tracking metastatic dissemination and tumor growth using longitudinal imaging and ctDNA

Abstract Metastatic lung cancer is a heterogeneous disease, characterized by different patterns of clinical progression and therapy response. The scale of this heterogeneity on a lesion specific level has yet to be quantified but is of clinical importance because it may provide an indication of molecular mechanisms underpinning metastasis growth. Currently, whether metastasis growth patterns can be predicted by the primary tumor or governed by metastasis specific characteristics is not known. Furthermore, circulating tumor DNA (ctDNA) has proven useful to predict disease relapse, but how closely it reflects metastatic growth post relapse is unclear. In 104 patients enrolled in the TRACERx study with disease relapse post-surgical resection of the primary tumor, lesion volumetric dynamics were tracked in 460 metastases. Total volume growth rate (TVGR) was calculated using CT imaging performed between disease relapse and death. All patients had whole exome sequencing (WES) of the primary tumor. For 19 patients enrolled in the PEACE autopsy study WES and RNAseq from 60 metastases visible on imaging prior to death and subsequently sampled at autopsy were analyses. In 29 patients, ctDNA was used to track 200 tumor-specific mutations to assess tumor burden and detect metastatic subclones. High TVGR correlated with poor survival (hazard ratio for death 1st vs 2nd tertile was 0.21, p<0.001; 2nd vs 3rd tertile was 0.51, p=0.04). Primary tumor subclonal whole genome doubling was predictive of high TVGR. There was considerable heterogeneity in the growth rate of metastases within patients. The anatomical location of metastases contributed to this, extrathoracic soft tissue and pleura had the highest growth rates, whilst lymph node and adrenal the lowest (p<0.001). Molecular attributes differed between metastases, with fast growing metastases being enriched for proliferation pathway gene expression. It was observed that the most prevalent population of cells, or clone, in the fastest growing metastasis within a patient was exclusive to that metastasis, suggesting that genomic features that characterize the clone might support rapid growth. ctDNA tracked with tumor burden post relapse and patients with extrathoracic relapse had higher levels of ctDNA. In 9 patients, metastasis specific mutations identified at autopsy and in ctDNA, were used to determine the proportion of ctDNA shed by different metastatic sites. ctDNA subclonal fraction was found to track with changes in lesion volumes during disease progression. This work highlights significant heterogeneity in metastatic growth rates which can potentially be attributed to the presence of distinct genomic features which may dictate tumor growth rate. ctDNA accurately reproduces patterns of radiological disease progression and when combined with longitudinal imaging and tumor DNA sequencing, can accurately reconstruct the natural history of cancer evolution. Citation Format: Wing Kin Liu, Boyue Ding, Hessey Sonya, Carlos Martinez-Ruiz, Cristina Naceur-Lombardelli, Corentin Richard, Hyothaek Lee, Catarina Veiga, Kishen Patel, Ariana Huebner, Allan Hackshaw, Christopher Abbosh, Alexander M. Frankell, Gary Royle, Charles Swanton, Mariam Jamal-Hanjani. Tracking metastatic dissemination and tumor growth using longitudinal imaging and ctDNA [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 4136.

Construction of a prognostic model for hepatocellular carcinoma patients receiving transarterial chemoembolization treatment based on the Tumor Burden Score

BackgroundPatients with hepatocellular carcinoma (HCC) who undergo transarterial chemoembolization (TACE) may have varied outcomes based on their liver function and tumor burden diversity. This study aims to assess the prognostic significance of the tumor burden score (TBS) in these patients and develop a prognostic model for their overall survival.MethodsThe study involved a retrospective analysis of 644 newly diagnosed HCC patients undergoing TACE treatment. The individuals were assigned randomly to a training cohort (n = 452) and a validation cohort (n = 192). We utilized a multivariate Cox proportional risk model to identify independent preoperative predictive factors. We then evaluated model performance using the area under the curve (AUC), consistency index (c-index), calibration curve, and decision curve analysis (DCA) methods.ResultsThe multivariate analysis revealed four prognostic factors associated with overall survival: Tumor Burden Score, Tumor Extent, Types of portal vein invasion (PVI), and Child-Pugh score. The total score was calculated based on these factors. The model demonstrated strong discriminative ability with high AUC values and c-index, providing high net clinical benefits for patients. Based on the model’s scoring results, patients were categorized into high, medium, and low-risk groups. These results were validated in the validation cohort.ConclusionsThe tumor burden score shows promise as a viable alternative prognostic indicator for assessing tumor burden in cases of HCC. The new prognostic model can place patients in one of three groups, which will estimate their individual outcomes. For high-risk patients, it is suggested to consider alternative treatment options or provide the best supportive care, as they may not benefit significantly from TACE treatment.

Analytical performance validation of aPROMISE platform for prostate tumor burden, index and dominant tumor assessment with 18F-DCFPyL PET/CT. A pilot study

To validate the performance of automated Prostate Cancer Molecular Imaging Standardized Evaluation (aPROMISE) in quantifying total prostate disease burden with 18F-DCFPyL PET/CT and to evaluate the interobserver and histopathologic concordance in the establishment of dominant and index tumor. Patients with a recent diagnosis of intermediate/high-risk prostate cancer underwent 18F-DCFPyL-PET/CT for staging purpose. In positive-18F-DCFPyL-PET/CT scans, automated prostate tumor segmentation was performed using aPROMISE software and compared to an in-house semiautomatic-manual guided segmentation procedure. SUV and volume related variables were obtained with two softwares. A blinded evaluation of dominant tumor (DT) and index tumor (IT) location was assessed by both groups of observers. In histopathological analysis, Gleason, International Society of Urological Pathology (ISUP) group, DT and IT location were obtained. We compared all the obtained variables by both software packages using intraclass correlation coefficient (ICC) and Cohen’s kappa coefficient (k) for the concordance analysis. Fifty-four patients with a positive 18F-DCFPyL PET/CT were evaluated. The ICC for the SUVmax, SUVpeak, SUVmean, tumor volume (TV) and total lesion activity (TLA) was: 1, 0.833, 0.615, 0.494 and 0.950, respectively (p < 0.001 in all cases). For DT and IT detection, a high agreement was observed between both softwares (k = 0.733; p < 0.001 and k = 0.812; p < 0.001, respectively) although the concordances with histopathology were moderate (p < 0001). The analytical validation of aPROMISE showed a good performance for the SUVmax, TLA, DT and IT definition in comparison to our in-house method, although the concordance was moderate with histopathology for DT and IT.

Surgical evidence-based comparison of [68Ga]Ga-FAPI-04 PET and MRI-DWI for assisting debulking surgery in ovarian cancer patients.

Imaging assessment of abdominopelvic tumor burden is crucial for debulking surgery decision in ovarian cancer patients. This study aims to compare the efficiency of [68Ga]Ga-FAPI-04 FAPI PET and MRI-DWI in the preoperative evaluation and its potential impact to debulking surgery decision. Thirty-six patients with suspected/confirmed ovarian cancer were enrolled and underwent integrated [68Ga]Ga-FAPI-04 PET/MRI. Nineteen patients (15 stage III-IV and 4 I-II stage) who underwent debulking surgery were involved in the diagnostic efficiency analysis. The images of [68Ga]Ga-FAPI-04 PET and MRI-DWI were visually analyzed respectively. Immunohistochemistry on FAP was performed in metastatic lesions to investigate the radiological missing of [68Ga]Ga-FAPI-04 PET as well as its different performance in primary debulking surgery (PDS) and interval debulking surgery (IDS) patients. Potential imaging impact on management was also studied in 35 confirmed ovarian cancer patients. [68Ga]Ga-FAPI-04 PET displayed higher sensitivity (76.8% vs.59.9%), higher accuracy (84.9% vs. 80.7%), and lower missing rate (23.2% vs. 40.1%) than MRI-DWI in detecting abdominopelvic metastasis. The diagnostic superiority of [68Ga]Ga-FAPI-04 PET is more obvious in PDS patients but diminished in IDS patients. [68Ga]Ga-FAPI-04 PET outperformed MRI-DWI in 70.8% abdominopelvic regions (17/24), which contained seven key regions that impact the resectability and surgical complexity. MRI-DWI hold advantage in the peritoneal surface of the bladder and the central tendon of the diaphragm. Of the contradictory judgments between the two modalities (14.9%), [68Ga]Ga-FAPI-04 PET correctly identified more lesions, particularly in PDS patients (73.8%). In addition, FAP expression was independent of lesion size and decreased in IDS patients. [68Ga]Ga-FAPI-04 PET changed 42% of surgical planning that was previously based on MRI-DWI. [68Ga]Ga-FAPI-04 PET is more efficient in assisting debulking surgery in ovarian cancer patients than MRI-DWI. Integrated [68Ga]Ga-FAPI-04 PET/MR imaging is a potential method for planning debulking surgery in ovarian cancer patients.

Quantitative assessment of bone marrow infiltration and characterization of tumor burden using dual-layer spectral CT in patients with multiple myeloma.

The aim of the study was to evaluate whether virtual calcium subtraction (VNCa) image extracted from dual-layer spectral CT could estimate bone marrow (BM) infiltration with MRI as the reference standard and characterize tumor burden in patients with multiple myeloma (MM). Forty-seven patients with newly diagnosed MM were retrospectively enrolled. They had undergone whole-body low-dose dual-layer spectral CT (DLCT) and whole-body MRI within one week. VNCa images with calcium-suppressed (CaSupp) indices ranging from 25 to 95 at an interval of 10 and apparent diffusion coefficient (ADC) maps were quantitatively analyzed on vertebral bodies L1-L5 at the central slice of images. The optimal combination was selected by correlation analysis between CT numbers and ADC values. Then, it was used to characterize tumor burden by correlation analysis and receiver operating characteristic (ROC) curves analysis, including plasma cell infiltration rate (PCIR), high serum-free light chains (SFLC) ratio and the high-risk cytogenetic (HRC) status. The most significant quantitative correlation between CT numbers of VNCa images and ADC values could be found at CaSupp index 85 for averaged L1-L5 (r = 0.612, p < 0.001). It allowed quantitative evaluation of PCIR (r = 0.835, p < 0.001). It could also anticipate high SFLC ratio and the HRC status with area under the curve (AUC) of 0.876 and 0.760, respectively. The VNCa measurements of averaged L1-L5 showed the highest correlation with ADC at CaSupp index 85. It could therefore be used as additional imaging biomarker for non-invasive assessment of tumor burden if ADC is not feasible.

Circulating tumor cells in patients with cervical cancer undergoing chemoradiotherapy combined with brachytherapy.

Circulating tumor cells (CTCs) have significant potential to become an important tool for monitoring the effects of treatment in solid tumors. The present study reports the occurance of CTCs in cervical cancer (CC) patients during radical chemoradiotherapy (CRT), including brachytherapy (BRT), and during the follow-up period. Patients diagnosed with CC treated with radical CRT were included in the study (n=30). A total of 167 CTC-tests (MetaCell®) were provided at predefined testing time points during the study follow-up (e.g., before CRT, after CRT, every three months of follow-up). In parallel with CTC-testing, SCC-Ag were measured to compare their predictive values during treatment. CTCs were present in 96% (25/26) of patients at the time of diagnosis and in 61% (14/23) after treatment. Patients who relapsed during the 36-month follow-up (n=10) showed an elevation in pre-treatment CTC- numbers, similarly there was a significant increase in pre-treatment SCC-Ag. As next, an increased number of CTCs was observed approximately 12 weeks before relapse was diagnosed by standard imaging modalities (MRI, US, PET-CT) in 3 of 4 patients. In addition to standardized vital cytomorphology of enriched CTCs, quantitative PCR (qPCR) was used to inform the nature of CTCs before treatment. Analysis revealed increased SOX2 and POUSF expression in CTCs in the group of patients with recurrence (P < 0.02). Disease aggressiveness may be related to increased expression of stem cell markers, as found in samples from relapsed patients. CTCs may be an aid to assess tumor burden and disease aggressiveness. An increase in CTCs precedes an increase in SCC-Ag and confirmation of relapse by imaging, as shown in our study.

Deep learning-based whole-body characterization of prostate cancer lesions on [68Ga]Ga-PSMA-11 PET/CT in patients with post-prostatectomy recurrence.

The automatic segmentation and detection of prostate cancer (PC) lesions throughout the body are extremely challenging due to the lesions' complexity and variability in appearance, shape, and location. In this study, we investigated the performance of a three-dimensional (3D) convolutional neural network (CNN) to automatically characterize metastatic lesions throughout the body in a dataset of PC patients with recurrence after radical prostatectomy. We retrospectively collected [68Ga]Ga-PSMA-11 PET/CT images from 116 patients with metastatic PC at two centers: center 1 provided the data for fivefold cross validation (n = 78) and internal testing (n = 19), and center 2 provided the data for external testing (n = 19). PET and CT data were jointly input into a 3D U-Net to achieve whole-body segmentation and detection of PC lesions. The performance in both the segmentation and the detection of lesions throughout the body was evaluated using established metrics, including the Dice similarity coefficient (DSC) for segmentation and the recall, precision, and F1-score for detection. The correlation and consistency between tumor burdens (PSMA-TV and TL-PSMA) calculated from automatic segmentation and artificial ground truth were assessed by linear regression and Bland‒Altman plots. On the internal test set, the DSC, precision, recall, and F1-score values were 0.631, 0.961, 0.721, and 0.824, respectively. On the external test set, the corresponding values were 0.596, 0.888, 0.792, and 0.837, respectively. Our approach outperformed previous studies in segmenting and detecting metastatic lesions throughout the body. Tumor burden indicators derived from deep learning and ground truth showed strong correlation (R2 ≥ 0.991, all P < 0.05) and consistency. Our 3D CNN accurately characterizes whole-body tumors in relapsed PC patients; its results are highly consistent with those of manual contouring. This automatic method is expected to improve work efficiency and to aid in the assessment of tumor burden.

Abstract A177: In vivo TuBa-seq growth profiling identifies a differential role of the Tbx2 subfamily in oncogene-negative versus Kras-driven lung cancers

Abstract Lung adenocarcinoma (LUAD) is a complex cancer driven by diverse combinations of oncogenic and tumor suppressive events. The TBX2 subfamily genes, including TBX2, TBX3, TBX4, and TBX5, are known to play a crucial role in lung development as master transcriptional regulators. Our previous clinical and in vitro studies found that their expression is significantly suppressed in LUADs, suggesting a potential tumor suppressor role through modulating tumor methylation patterns in early tumorigenesis. However, the role of TBX2 subfamily genes in other cancer types is paradoxical, with both oncogenic and tumor suppressive effects being reported. Herein, we employed the Tumor Barcoding with Ultradeep Sequencing (Tuba-seq) and CRISPR/Cas9-mediated genome editing technologies to investigate the putative tumor suppressive role of TBX2 genes functionally and quantitatively and their downstream targets in genetically engineered mouse models of LUAD. Lung tumors were initiated by intratracheal intubation with pooled lentiviral-Cre vectors targeting each gene independently with two different sgRNAs per gene. To enable the unique identification of each tumor and its corresponding sgRNA, we utilized Lenti-sgRNA/Cre vectors harboring barcodes specific to each targeted gene. Initial assessment of tumor burden was carried out through fluorescence microscopy, lung weight measurements, and histological analysis. To simultaneously determine the number of neoplastic cells corresponding to each gene knockout, the barcoded region was amplified from genomic DNA extracted from bulk tumor-bearing lung samples and sequenced. Quantification of tumor sizes was carried at 6 and 20 weeks after tumor initiation. Hyperplasia, adenomas, and/or early adenocarcinomas within the lungs were detected among different genetic backgrounds and throughout the study time intervals. Specifically, the inactivation of Tbx2, Tbx3, Tbx4, Tbx5, and Cdh2, increased tumor initiation and growth in the oncogene-negative mouse model (n=8). However, strikingly, inactivation of Tbx3, Tbx4, and Cdh2 suppressed tumorigenesis in a KRAS-driven genetic background while Tbx2, Tbx5, and Tnfaip3, consistently exhibited tumor suppressive effects (n=9). Further investigation is needed to understand these newly discovered interactions between the TBX2 subfamily critical developmental pathway and Ras signaling in modulating lung cancer progression. These insights emphasize the importance of considering tumor suppressor phenotypic heterogeneity and their context-dependent roles when developing targeted therapeutic approaches for lung adenocarcinoma and other cancers. Citation Format: Athar Khalil, Mira Rahm, Zachary Faber, Madeline Bedrock, Xiangzhen Wei, Bindi Patel, Christopher Mcfarland. In vivo TuBa-seq growth profiling identifies a differential role of the Tbx2 subfamily in oncogene-negative versus Kras-driven lung cancers [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2023 Oct 11-15; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2023;22(12 Suppl):Abstract nr A177.

Apparent diffusion coefficient measurements of bone marrow infiltration patterns in multiple myeloma for the assessment of tumor burden - a feasibility study.

The purpose of our study was to explore and compare the tumor burden of different bone marrow infiltration patterns and evaluate the feasibility of apparent diffusion coefficient (ADC) value to identify patterns in multiple myeloma (MM). Ninety-three patients with newly diagnosed multiple myeloma and 23 controls had undergone routine magnetic resonance imaging (MRI) and diffusion-weighted MRI (DWI) from January 2019 to November 2020. Five bone marrow (BM) infiltration patterns were allocated according to routine MRI. The laboratory data and ADC values of patterns were analyzed and compared. ROC analysis was used to establish the best diagnostic ADC threshold value for identifying these patterns and distinguishing normal pattern from controls. Besides, the correlation between the ADC values of diffuse pattern and the plasma cells ratio was assessed. The values of hemoglobin, beta-2 microglobulin (β2-MG), plasma cell, M protein, the percentages of stage, high-risk fluorescence in situ hybridization, and ADC values showed significant difference among patterns. ADCmean at a specific value (368.5×10-6 mm2/s) yielded a maximum specificity (95.5%) and sensitivity (92.0%) in diagnosing MM. A specific value (335.5×10-6mm2/s) yielded a maximum specificity (84.7%) and sensitivity (88.0%) in discriminating visually normal pattern in MM from controls. There was a moderate positive correlation between the plasma cells ratio and ADCs of diffuse infiltration patterns (r = 0.648, P < 0.001). The bone marrow infiltration patterns in MM patients can indicate the tumor burden and ADC value has the ability to discriminate these patterns objectively.

Examining the Relationship and Prognostic Significance of Cell-Free DNA Levels and the PSMA-Positive Tumor Volume in Men with Prostate Cancer: A Retrospective-Prospective [68Ga]Ga-PSMA-11 PET/CT Study.

Functional imaging with prostate-specific membrane antigen (PSMA) ligands has emerged as the standard imaging method for prostate cancer (PCA). In parallel, the analysis of blood-derived, cell-free DNA (cfDNA) has been shown to be a promising quantitative biomarker of PCA aggressiveness and patient outcome. This study aimed to evaluate the relationship and prognostic value of cfDNA concentrations and the PSMA-positive tumor volume (PSMA-TV) in men with PCA undergoing [68Ga]Ga-PSMA-11 PET/CT imaging. Methods: We recruited 148 men with histologically proven PCA (mean age, 70.7 ± 7.7 y) who underwent [68Ga]Ga-PSMA-11 PET/CT (184.9 ± 18.9 MBq) and blood sampling between March 2019 and August 2021. Among these, 74 (50.0%) had hormone-sensitive PCA and 74 (50.0%) had castration-resistant PCA (CRPC). All patients provided written informed consent before blood sample collection and imaging. The cfDNA was extracted and quantified, and PSMA-expressing tumor lesions were delineated to extract the PSMA-TVs. The Spearman coefficient assessed correlations between PSMA-TV and cfDNA concentrations and cfDNA's relation with clinical parameters. The Kruskal-Wallis test examined the mean cfDNA concentration differences based on PSMA-TV quartiles for significantly correlated patient groups. Log-rank and multivariate Cox regression analyses evaluated the prognostic significance of high and low cfDNA and PSMA-TV levels for overall survival. Results: Weak positive correlations were found between cfDNA concentration and PSMA-TV in the overall group (r = 0.16, P = 0.049) and the CRPC group (r = 0.31, P = 0.007) but not in hormone-sensitive PCA patients (r = -0.024, P = 0.837). In the CRPC cohort, cfDNA concentrations significantly differed between PSMA-TV quartiles 4 and 1 (P = 0.002) and between quartiles 4 and 2 (P = 0.016). Survival outcomes were associated with PSMA-TV (P < 0.0001, P = 0.004) but not cfDNA (P = 0.174, P = 0.12), as per the log-rank and Cox regression analysis. Conclusion: These findings suggest that cfDNA might serve as a biomarker of advanced, aggressive CRPC but does not reliably reflect total tumor burden or prognosis. In comparison, [68Ga]Ga-PSMA-11 PET/CT provides a highly granular and prognostic assessment of tumor burden across the spectrum of PCA disease progression.