Distant Metastatic Sites Research Articles

Weaving the nest: extracellular matrix roles in pre-metastatic niche formation.

The discovery that primary tumors condition distant organ sites of future metastasis for seeding by disseminating tumor cells through a process described as the pre-metastatic niche (PMN) formation revolutionized our understanding of cancer progression and opened new avenues for therapeutic interventions. Given the inherent inefficiency of metastasis, PMN generation is crucial to ensure the survival of rare tumor cells in the otherwise hostile environments of metastatic organs. Early on, it was recognized that preparing the "soil" of the distal organ to support the outgrowth of metastatic cells is the initiating event in PMN development, achieved through the remodeling of the organ's extracellular matrix (ECM). Remote restructuring of ECM at future sites of metastasis under the influence of primary tumor-secreted factors is an iterative process orchestrated through the crosstalk between resident stromal cells, such as fibroblasts, epithelial and endothelial cells, and recruited innate immune cells. In this review, we will explore the ECM changes, cellular effectors, and the mechanisms of ECM remodeling throughout PMN progression, as well as its impact on shaping the PMN and ultimately promoting metastasis. Moreover, we highlight the clinical and translational implications of PMN ECM changes and opportunities for therapeutically targeting the ECM to hinder PMN formation.

A disease registry study to prospectively observe treatment patterns and outcomes in patients with HER2+ unresectable locally advanced or metastatic breast cancer (aBC): Interim results of the ESTHER study (NCT02393924).

e13039 Background: Over the last decade the standard-of-care treatment for patients with HER2+ aBC has included anti-HER2 therapies often combined with chemotherapy. These approaches have shown efficacy in clinical trials which have recruited patients in restricted populations defined by lines of therapy and previous treatments. There are few data regarding the long-term outcomes of patients treated with these regimens, including those with brain metastases. We conducted a prospective, multicentre non-interventional study to observe anti-cancer treatment regimens and clinical outcomes in patients with HER2 positive aBC. Methods: Adult patients diagnosed with HER2-positive aBC within the last 6 months were included. No specific treatment approach or course was mandated by the protocol. Source data was taken from the patient’s chart and other medical records, then reported by means of an electronic data collection system. Data regarding treatment received, efficacy (progression-free and overall survival (PFS), response rates (RR) and development of CNS metastases) and safety (including cardiac toxicity) were captured. Results: Between February 2015 and April 2018, 311 eligible patients were recruited with median age 57 years (24-96). At diagnosis of aBC the most common distant metastatic sites were bone (n = 145;47%), liver (n=117;38%), lung (n=100;32%) and brain (n=21;7%). First line treatment was with pertuzumab (P)/trastuzumab(T)/chemotherapy (n=212;68%), T/chemotherapy (n=45;14%), other T combinations without P (n=19;6%), Trastuzumab Emtansine regimens without T or P (n=16;5%) (19; 5% other combinations). Patients’ status as of cut-off date for this analysis (28th Feb 2022, median follow-up 44.1 months) is shown. The median PFS of patients treated in the 1st, 2nd and 3rd lines was 26.7 months, 10.7 months and 8.6 months. At the time of this analysis an additional 60 patients (19%) had developed brain metastases during first line. The number of patients starting 2nd, 3rd and 4th line treatment with brain metastases were 28 (22%), 17 (40%), 7 (37%) respectively. Conclusions: In routine clinical practice, as reflected by this registry, at least 40% of patients who initiate first line therapy for advanced breast cancer do not proceed to 3rd line therapy, and brain metastases become increasingly common. These findings have implications for selection of optimal 2nd and 3rd line treatment. Clinical trial information: ISRCTN02393924 . [Table: see text]

A rapidly-growing erythematous nodule on the right upper neck

A rapidly-growing erythematous nodule on the right upper neck

Metaplastic Breast Carcinoma in U.S. Population: Racial Disparities, Survival Benefit of Adjuvant Chemoradiation and Future Personalized Treatment with Genomic Landscape.

In this population-based study, we aim to identify factors that are influential on the survival outcome in MBC and investigate novel molecular approaches in personalized disease management. The data of this study were collected from the SEER database from 2000-2018. A total of 5315 cases were extracted from the database. The data were evaluated for demographics, tumor characteristics, metastasis, and treatment. Survival analysis was completed by using SAS software for multivariate analysis, univariate analysis, and non-parametric survival analysis. The molecular data with the most common mutations in MBC were extracted from the Catalogue of Somatic Mutations in Cancer (COSMIC) database. The mean age at the time of presentation was 63.1 with a standard deviation (SD) of 14.2 years. Most patients were White (77.3%) with 15.7% Black patients, 6.1% Asian or Pacific Islander, and 0.5% American Indian. Histologically, most of the reported tumors were grade III (74.4%); 37% of the cases were triple negative (ER-, PR- and HER2-), whereas the hormone status was unknown in 46% of the cases. Spread was localized in 67.3% of patients while 26.3% had regional spread and 6.3% had distant metastases. Most tumors were unilateral (99.9%) and between 20-50 mm in size (50.6%). The lungs were the most common site for distant metastasis at diagnosis (3.42%) followed by bone (1.94%), liver (0.98%), and brain (0.56%). A combination of surgery, chemotherapy, and radiation therapy was the most common treatment with a cause-specific survival rate of 78.1% (95% CI = 75.4-80.4). The overall survival rate at 5 years was 63.6% (95% confidence interval (CI) = 62.0-65.1) with a cause-specific survival of 71.1% (95% CI = 69.5-72.6). Cause-specific survival was found to be 63.2% (95% CI = 58.9-67.1) in Black patients as compared to 72.4% (95% CI = 70.1-74.1) in White patients. Black patients also presented with higher rates of grade III disease, distant metastasis, and larger tumor size. On multivariate analysis, age > 60, grade III+, metastasis, and tumor size > 50 mm were associated with worse survival. The most common mutations in MBC identified in COSMIC data were TP53, PIK3CA, LRP1B, PTEN, and KMT2C. Though rare, MBC is aggressive, with poor prognosis associated with high-grade tumors, metastasis, tumor size over 50 mm, and advanced age at the time of presentation. Overall, Black women had worse clinical outcomes. MBC is difficult to treat and carries a poor prognosis that affects various races disproportionately. Continued enhancement of treatment strategies to foster more individualized care as well as continued enrollment in clinical trials are needed to improve outcomes among patients with MBC.

Survival analysis and prognosis of patients with breast cancer with pleural metastasis.

Breast cancer (BC) is the most common malignant cancer. The prognosis of patients differs according to the location of distant metastasis, with pleura being a common metastatic site in BC. Nonetheless, clinical data of patients with pleural metastasis (PM) as the only distant metastatic site at initial diagnosis of metastatic BC (MBC) are limited. The medical records of patients who were hospitalized in Shandong Cancer Hospital between January 1, 2012 and December 31, 2021 were reviewed, and patients eligible for the study were selected. Survival analysis was conducted using Kaplan-Meier (KM) method. Univariate and multivariate Cox proportional-hazards models were used to identify prognostic factors. Finally, based on these selected factors, a nomogram was constructed and validated. In total, 182 patients were included; 58 (group A), 81 (group B), and 43 (group C) patients presented with only PM, only lung metastasis (LM), and PM combined with LM, respectively. The KM curves revealed no significant difference in overall survival (OS) among the three groups. However, in terms of survival after distant metastasis (M-OS), the difference was significant: patients with only PM exhibited the best prognosis, whereas those with PM combined with LM exhibited the worst prognosis (median M-OS: 65.9, 40.5, and 32.4 months, respectively; P = 0.0067). For patients with LM in groups A and C, those with malignant pleural effusion (MPE) exhibited significantly worse M-OS than those without MPE. Univariate and multivariate analyses indicated that primary cancer site, T stage, N stage, location of PM, and MPE were independent prognostic factors for patients with PM without other distant metastasis. A nomogram prediction model incorporating these variables was created. According to the C-index (0.776), the AUC values of the 3-, 5-, and 8-year M-OS (0.86, 0.86, and 0.90, respectively), and calibration curves, the predicted and actual M-OS were in good agreement. BC patients with PM only at the first diagnosis of MBC exhibited a better prognosis than those with LM only or PM combined with LM. We identified five independent prognostic factors associated with M-OS in this subset of patients, and a nomogram model with good predictive efficacy was established.

Patterns of Distant Metastasis in Head and Neck Cancer in a Tertiary Care Centre.

Objectives/Hypothesis To find out the frequency and location of distant metastasis in head and neck malignancies. Our study also aims to find out the most common site leading to distant metastasis and the management of these distant metastasis cases. Methods 1558 patients treated for head and neck malignancy between 2017 and 2021 were retrospectively reviewed. The frequency and proportions were used to produce descriptive statistics. Results The highest number of head and neck malignancy cases were reported in the oral cavity which included 943 cases (60.52%). Patients with distant metastasis (M1) accounted for 4.73 percent of all cases (n = 90). Nasopharyngeal malignancy cases showed the highest M1 frequency (29.03%), whereas oral cavity patients had the lowest frequency (2.75%). The most common site of distant metastasis was in the lung (64%) followed by bone (18%) and the liver (11%). CT scan of the neck and thorax was the most commonly used diagnostic modality. The most common histopathological finding was squamous cell carcinoma (85%). Multimodality treatment was employed for most of the detected cases. Conclusion Distant metastasis at presentation is rare in head and neck cancer. The rate of distant metastasis in the present study was 4.73%, with the lung being the most common site. The overall survival of these patients depends on a variety of factors and more studies are needed in this regard.

Abscopal responses in patients with metastatic melanoma involving skin and subcutaneous tissues treated with intralesional IL2 plus BCG.

Cutaneous melanoma is relatively common with increasing incidence and significant mortality. While the mainstay of therapy is surgical, patients with stage III and IV disease fare poorer than those with early-stage disease and often benefit from adjuvant therapies. While systemic immunotherapy has changed the landscape of melanoma treatment, for some patients systemic toxicities related to these treatments prohibit successful administration or completion of therapy. Moreover, it is becoming increasingly evident that nodal, regional, and in-transit disease appears to be resistant to systemic immunotherapy relative to responses observed in distant metastatic disease sites. In this scenario, intralesional immunotherapies may offer benefit. In this case series, we describe the use of intralesional IL-2 and BCG at our institution in ten patients with in-transit plus or minus distant cutaneous metastatic melanoma over the last twelve years. All patients received intralesional IL2 and BCG. Both treatments were very well tolerated with only grade 1/2 adverse events. In our cohort, complete clinical response was 60% (6/10), progressive disease in 20% (2/10), and no response in 20% (2/10) of patients. The overall response rate (ORR) was 70%. The median overall survival was 35.5 months and mean overall survival 43 months in this cohort. Herein we further highlight the clinical, histopathological, and radiological course of two complete responders, showing evidence of an abscopal effect with resolution of distant untreated metastasis. Together, this limited data supports the safe and effective use of intralesional IL2 and BCG for the treatment of metastatic or in-transit melanoma in this challenging patient cohort. To our knowledge, this is the first formal study to report on this combination therapy for the treatment of melanoma.

Predictive factors of distant metastasis in surgically treated HPV-positive tonsil cancer.

Human papilloma virus (HPV)-related tonsil cancer is associated with favorable outcomes. The purpose of this study was to define factors affecting distant metastasis in patients with surgically treated HPV-positive tonsil cancer. The present study enrolled 76 patients diagnosed with HPV-positive tonsil cancer who underwent primary surgery between January 2010 and December 2021. Twelve (15.7%) patients experienced a distant failure with a median follow-up time of 43 months. Sites of distant metastasis included the lung (n = 10), liver (n = 1), and brain (n = 1). Upon multivariate analysis, an advanced T stage (odds ratio [OR]: 13.94, 95% confidence interval [CI]: 1.29-149.863, p = 0.003) and margin involvement (OR: 5.96, 95% CI: 1.33-26.76, p = 0.02) were independent predictors of distant metastases. The five-year disease-specific survival for the entire cohort was 85%. The multivariate analysis confirmed that distant metastasis (hazard ratio [HR]: 12.688, 95% CI: 3.424-47.016; p < 0.001) and margin involvement (HR: 6.243; 95% CI: 1.681-23.191; p = 0.006) were significant factors associated with the five-year disease-specific survival. HPV-positive tonsil cancer patients with an advanced T stage and a positive surgical margin have a substantial risk of distant metastases. Distant metastasis and margin involvement are factors that affect their survival.

Metastasis-Directed Local Therapy of Hepatic Oligometastasis from Colorectal Cancer and Future Perspective in Radiation Therapy.

Introduction of the concept for oligometastasis led to wide application of metastasis-directed local ablative therapies for metastatic colorectal cancer (CRC). By application of the metastasis-directed local ablative therapies including surgical resection, radiofrequency ablation (RFA), and stereotactic ablative body radiotherapy (SABR), the survival outcomes of patients with metastatic CRC have improved. The liver is the most common distant metastatic site in CRC patients, and recently various metastasis-directed local therapies for hepatic oligometastasis from CRC (HOCRC) are widely used. Surgical resection is the first line of metastatic-directed local therapy for HOCRC, but its eligibility is very limited. Alternatively, RFA can be applied to patients who are ineligible for surgical resection of liver metastasis. However, there are some limitations such as inferior local control (LC) compared with surgical resection and technical feasibility based on location, size, and visibility on ultrasonography of the liver metastasis. Recent advances in radiation therapy technology have led to an increase in the use of SABR for liver tumors. SABR is considered complementary to RFA for patients with HOCRC who are ineligible for RFA. Furthermore, SABR can potentially result in better LC for liver metastases > 2-3 cm compared with RFA. In this article, the previous studies regarding curative metastasis-directed local therapies for HOCRC based on the radiation oncologist's and surgeon's perspective are reviewed and discussed. In addition, future perspectives regarding SABR in the treatment of HOCRC are suggested.

Canine squamous cell carcinoma: Electrochemotherapy association with surgery and correlation with overall survival.

Squamous cell carcinoma (SCC) is an important malignancy in dogs, due to its incidence and clinical presentation, which can be of locally aggressive single or multiple lesions with a metastatic potential. The objective of this investigation was to evaluate SCC response to treatment, anatomopathological and immunohistochemical characteristics, disease-free interval and overall survival time. 54 dogs with histopathologically diagnosed SCC were included in this study. Their mean age was 9.16 years with a range of 1-14 years. Of the 54 animals in the study, 34 (65.4%) had white skin and white fur coats. There was a significant correlation between fur coat colour and the development of tumours in areas of sun exposure (p=.001). Animals with tumours in areas of the body exposed to the sun had longer overall survival time than animals with tumours in areas not associated with sun exposure (p=.001). Surgery combined with electrochemotherapy (ECT) yielded a survival rate 32% higher than using a surgical approach alone (HR=0.32, p=.038, IC=0.11-0.94). ECT, with or without surgery, had an objective response rate of 90.9%. Local lymph node and/or distant site metastasis at diagnosis, or at some point during follow-up, occurred in 34.6% (18/52) of animals. Animals with tumours in sun exposed locations had more aggressive histopathological characteristics but had longer overall survival time. This is probably due to individualised therapeutic treatment with both surgery and ECT.

Prognosis of thyroid carcinoma patients with osseous metastases: an SEER-based study with machine learning.

Osseous metastasis (OM) is the second most common site of thyroid cancer distant metastasis and presents a poor prognosis. Accurate prognostic estimation for OM has clinical significance. Ascertain the risk factors for survival and develop an effective model to predict the 3-year, 5-year overall survival (OS) and cancer-specific survival (CSS) for thyroid cancer patients with OM. We retrieved the information of patients with OMs between 2010 and 2016 from the Surveillance, Epidemiology, and End Result Program. The Chi-square test, and univariate and multivariate Cox regression analyses were performed. Four machine learning (ML) algorithms, which were most commonly used in this field, were applied. A total of 579 patients having OMs were eligible. Advanced age, tumor size ≥ 40mm, combined with other distant metastasis were associated with worse OS in DTC OMs patients. Radioactive iodine (RAI) significantly improved CSS in both males and females. Among four ML models [logistic regression, support vector machines, extreme gradient boosting, and random forest (RF)], RF had the best performance [area under the receiver-operating characteristic curve: 0.9378 for 3-year CSS, 0.9105 for 5-year CSS, 0.8787 for 3-year OS, 0.8909 for 5-year OS]. The accuracy and specificity of RF were also the best. RF model shall be used to establish an accurate prognostic model for thyroid cancer patients with OM, not only from the SEER cohort but also intended for all thyroid cancer patients in the general population, which may be applicable in clinical practice in the future.

Abstract P4-07-01: Overall survival with locoregional surgery in de novo metastatic breast cancer

Abstract Background: Breast cancer remains the most frequent type of cancer in women, with de novo metastatic breast cancer (dnMBC) accounting for approximately 6-10% of patients. Advances in treatment of dnMBC have led to an increase in overall survival (OS), but the role of locoregional surgery remains unclear. Aim: To determine the value of locoregional surgery compared with no surgery on OS of women with dnMBC Settings and design: This study was designed as a randomized clinical study and was approved by the Ethics Committee of the Ethics Committee of Cangzhou Clinical College of Integrated Traditional Chinese and Western Medicine of Hebei Medical University (NO.20200212). Methods: Patient characteristics were previously reported in ASCO2022. Eighty-six patients with dnMBC were randomised to surgery of the primary tumor followed by systemic therapy (surgery group) or to primary systemic therapy without surgery (non-surgery group), by a computer generated block randomisation sequence. Randomisation was stratified by site of distant metastases, number of metastatic lesions, and molecular subtypes. Follow-up visits were conducted during treatment, monthly in first year, every 3 months thereafter. The primary endpoint was overall survival analysed by intention to treat. The stratified log-rank test and Cox proportional hazards model were used to compare OS between groups. The level for significance was set at p&amp;lt; 0.05. All analyses were performed with STATA 17. Results: Between Jan 3, 2019, and Mar 29, 2021, of the 103 women presenting with dnMBC, we randomly assigned 86 patients: 44 to surgery of the primary tumor followed by systemic therapy and 42 to primary systemic therapy without surgery. At data cut-off of Dec 1, 2021, median follow-up was 27 months with 44 deaths (surgery group n=21, non-surgery group n=23). The 2-year OS was 45.2% without and 52.3% with locoregional surgery (hazard ratio=0.59; 95% CI, 0.32 to 1.12; p = 0.11). The median OS was 25.5 months (95% CI, 23.52 to 29.38) in non-surgery group and 33 months (95% CI, 27.43 to 34.53) in surgery group. Conclusions: Our prospective randomized trial showed that compared with non-surgery counterparts, locoregional surgery does not improve OS of patients with dnMBC. Large, well-designed studies involving a large number of cases, multi-institution trials and longer follow-up are needed to verify the finding. Citation Format: Ren Chongxi, Sun Jianna, Kong Lingjun. Overall survival with locoregional surgery in de novo metastatic breast cancer [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P4-07-01.

Discordance of HER2-Low between Primary Tumors and Matched Distant Metastases in Breast Cancer.

We examined differences in HER2 expression between primary tumors and distant metastases, particularly within the HER2-negative primary breast cancer cohort (HER2-low and HER2-zero). The retrospective study included 191 consecutive paired samples of primary breast cancer and distant metastases diagnosed between 1995 and 2019. HER2-negative samples were divided into HER2-zero (immunohistochemistry [IHC] score 0) and HER2-low (IHC score 1+ or 2+/in situ hybridization [ISH]-negative). The main objective was to analyze the discordance rate between matched primary and metastatic samples, focusing on the site of distant metastasis, molecular subtype, and de novo metastatic breast cancer. The relationship was determined by cross-tabulation and calculation of Cohen's Kappa coefficient. The final study cohort included 148 paired samples. The largest proportion in the HER2-negative cohort was HER2-low [primary tumor 61.4% (n = 78), metastatic samples 73.5% (n = 86)]. The discordance rate between the HER2 status of primary tumors and corresponding distant metastases was 49.6% (n = 63) (Kappa -0.003, 95%CI -0.15-0.15). Development of a HER2-low phenotype occurred most frequently (n = 52, 40.9%), mostly with a switch from HER2-zero to HER2-low (n = 34, 26.8%). Relevant HER2 discordance rates were observed between different metastatic sites and molecular subtypes. Primary metastatic breast cancer had a significantly lower HER2 discordance rate than secondary metastatic breast cancer [30.2% (Kappa 0.48, 95%CI 0.27-0.69) versus 50.5% (Kappa 0.14, 95% CI -0.03-0.32)]. This highlights the importance of evaluating potentially therapy-relevant discordance rates between a primary tumor and corresponding distant metastases.

Predicting the site of distant metastases in breast cancer

Background. Distant organ tumor dissemination is a major cause of breast cancer-related deaths. Breast cancer can metastasize to several organs, and the most frequent metastatic sites include the bones, lungs and liver. There is a question what factors can influence the direction of spread of tumor cells to a particular organ.Material and Methods. We summarized the data available in the world literature on methods for prediction of the localization of distant metastases in breast cancer patients.Results. We divided the factors associated with the localization of distant metastases into two main groups: clinicopathological parameters of breast cancer patients and molecular features of tumor microenvironment and tumor cells (primary tumor and circulating tumor cells) or its derivates – exosomes. From our point of view, the most powerful clinicopathological factor predicting the distant metastasis site is a molecular subtype of primary tumor. We can conclude that luminal (HR+/HER2-) tumors are often characterized by single metastases and bones are the most common metastatic site, while TNBC and HER2-enriched tumors often metastasize to multiple sites, most commonly brain and liver. However, several authors did not reveal these associations in their studies. It likely indicates the existence of other factors that significantly affect the organotropism of metastasis. Numerous studies demonstrate the association of different molecules expressed on tumor cells with organotropic metastasis. However, these data are very fragmentary and rather contradictory.Conclusion. The found associations are common to all participants of metastatic cascade, but remains unclear which factors are essential and crucial in determining the direction of metastasis.

Molecular subtypes predict the preferential site of distant metastasis in advanced breast cancer: a nationwide retrospective study.

This study aimed to explore possible associations between molecular subtypes and site of distant metastasis in advanced breast cancer (ABC). 3577 ABC patients were selected from 21 hospitals of seven geographic regions in China from 2012-2014.A questionnaire was designed to collect medical information regarding demographic characteristics, risk factors, molecular subtype, recurrence/metastasis information, and disease-free survival (DFS). The cancers were classified into Luminal A, Luminal B, HER2-enriched and Triple Negative subtypes. Chi-square test and multivariate Cox proportional hazard models were performed to explore the associations between molecular subtypes and distant metastasis sites. A total of 2393 cases with molecular subtypes information were finally examined. Patients with Luminal A (51.1%) and Luminal B (44.7%) were most prone to bone metastasis, whereas liver metastasis was more frequently observed in HER2-enriched ABC patients (29.1%).The cumulative recurrence and metastasis rates of ABC patients at 36 months of DFS were the most significant within molecular types, of which Triple Negative was the highest (82.7%), while that of Luminal A was the lowest (58.4%). In the adjusted Cox regression analysis, Luminal B, HER2-enriched and Triple Negative subtypes increased the risk of visceral metastasis by 23%, 46% and 87% respectively. In addition, Triple Negative patients had a higher probability of brain metastasis (HR 3.07, 95% CI: 1.04-9.07). Molecular subtypes can predict the preferential sites of distant metastasis, emphasizing that these associations were of great help in choices for surveillance, developing appropriate screening and cancer management strategies for follow-up and personalized therapy in ABC patients.

Abstract B024: TBX2highmiR-375-3plowRBPJhigh signaling drives prostate cancer bone metastatic phenotype via exosomes

Abstract Recent studies have shown that exosome secretion by prostate cancer (PCa) cells fosters multiple facets of PCa progression and metastasis, mediated in particular through exosomal micro RNAs (miRs) that dictate gene expression changes. However, the molecular mechanisms through which exosomal miRs orchestrate bone remodeling that facilitates the establishment of a pre-metastatic niche (PMN) at the distant metastatic site i.e. bone remain elusive. We have identified that TBX2, a transcription factor that we previously reported plays a key role in PCa metastasis, represses miR-375-3p thereby resulting in de-repression/upregulation of its target RBPJ, an effector of Notch signaling and an established driver of PCa metastasis. Further, the unbiased identification of miR-375-3p as the topmost miR repressed by TBX2, in combination with experiments that genetically manipulate miR-375-3p in the context of TBX2 modulation, point to a crucial biological function of miR-375-3p as a key mediator in RBPJ regulation exerted by TBX2. In addition, the study highlights a dual level of RBPJ regulation by TBX2/miR-375-3p signaling i.e. via: a) gene expression changes at the intra-cellular or autocrine level, and b) gene expression changes at the distant site of bone metastasis through inter-cellular/endocrine communication via exosomes. Further, the study implicates TBX2high primary PCa cells in directing bone remodeling activity at the distant metastatic site in a paracrine mode via exosomes in addition to our previously reported role of TBX2 in mediating bone remodeling in an autocrine mode that occurs following metastatic dissemination. Taken together, our study unravels the role of TBX2/miR-375-3p/RBPJ signaling in PCa bone metastatic progression. Citation Format: Girijesh Kumar Patel, Sayanika Dutta, Hamed Khedmatgozar, Manisha Tripathi, Srinivas Nandana. TBX2highmiR-375-3plowRBPJhigh signaling drives prostate cancer bone metastatic phenotype via exosomes [abstract]. In: Proceedings of the AACR Special Conference: Cancer Metastasis; 2022 Nov 14-17; Portland, OR. Philadelphia (PA): AACR; Cancer Res 2022;83(2 Suppl_2):Abstract nr B024.

Abstract PR017: Differences in melanoma lipid metabolism among distinct metastatic sites

Abstract Metastasis is a very inefficient process in which few disseminated cancer cells survive. We developed a patient-derived xenograft assay in which melanomas engraft and spontaneously metastasize (Quintana Nature 456:593-598). Using this assay, we discovered that melanoma cells experience a spike in reactive oxygen species during metastasis and that distant metastasis is limited by oxidative stress (Piskounova Nature 527:186-191). Successfully metastasizing cells undergo reversible metabolic changes during metastasis that increase oxidative stress resistance. For example, melanoma cells in lymph experience less oxidative stress and form more metastases than melanoma cells in the blood (Ubellacker Nature 585:113-120). This is true in both patient-derived melanomas growing in immunocompromised mice and mouse melanomas growing in syngeneic immunocompetent mice. Cells metastasizing through blood, but not lymph, appear to undergo ferroptosis, a form of cell death marked by lipid oxidation. Multiple differences between lymph fluid and blood plasma may contribute to this difference in oxidative stress, including higher levels of oleic acid in lymph. Oleic acid is a monounsaturated fatty acid that protects melanoma cells from ferroptosis, apparently by reducing the abundance of oxidizable polyunsaturated fatty acids (PUFAs) in phospholipids. In the current study we found that some PUFAs sensitize melanoma cells to lipid peroxidation and cell death more than others. Moreover, we analyzed the lipid profiles of common sites of distant metastasis – liver, brain, kidney, pancreas, bone marrow, lung, and liver – and found that the PUFA compositions of these tissues varies significantly. This raises the possibility that metastasizing melanoma cells may incorporate more PUFAs into their phospholipid membranes and exhibit increased ferroptosis sensitivity in some metastatic sites as compared to others. We found that melanoma cells isolated from metastatic sites by flow cytometry had higher levels of PUFAs in their phospholipid membranes compared to those isolated from subcutaneous tissues. These cells isolated from distal sites also exhibited higher levels of lipid ROS and contained higher levels of oxidized lipid species compared to subcutaneous tumors. These data suggest that the lipid metabolism of metastatic tumors reflects both lipid availability in the metastatic site as well as cell-intrinsic differences in lipid metabolism, both of which contribute to lipid ROS. Both cell-intrinsic and cell-extrinsic lipid metabolism likely influence the ability of melanoma cells to survive in distinct metastatic sites during metastasis. Citation Format: Thomas P. Mathews, Sarah Muh, Arin B. Aurora, Sean J. Morrison. Differences in melanoma lipid metabolism among distinct metastatic sites [abstract]. In: Proceedings of the AACR Special Conference: Cancer Metastasis; 2022 Nov 14-17; Portland, OR. Philadelphia (PA): AACR; Cancer Res 2022;83(2 Suppl_2):Abstract nr PR017.

Size-advantage of monovalent nanobodies against the macrophage mannose receptor for deep tumor penetration and tumor-associated macrophage targeting.

Rationale: Nanobodies (Nbs) have emerged as an elegant alternative to the use of conventional monoclonal antibodies in cancer therapy, but a detailed microscopic insight into the in vivo pharmacokinetics of different Nb formats in tumor-bearers is lacking. This is especially relevant for the recognition and targeting of pro-tumoral tumor-associated macrophages (TAMs), which may be located in less penetrable tumor regions. Methods: We employed anti-Macrophage Mannose Receptor (MMR) Nbs, in a monovalent (m) or bivalent (biv) format, to assess in vivo TAM targeting. Intravital and confocal microscopy were used to analyse the blood clearance rate and targeting kinetics of anti-MMR Nbs in tumor tissue, healthy muscle tissue and liver. Fluorescence Molecular Tomography was applied to confirm anti-MMR Nb accumulation in the primary tumor and in metastatic lesions. Results: Intravital microscopy demonstrated significant differences in the blood clearance rate and macrophage targeting kinetics of (m) and (biv)anti-MMR Nbs, both in tumoral and extra-tumoral tissue. Importantly, (m)anti-MMR Nbs are superior in reaching tissue macrophages, an advantage that is especially prominent in tumor tissue. The administration of a molar excess of unlabelled (biv)anti-MMR Nbs increased the (m)anti-MMR Nb bioavailability and impacted on its macrophage targeting kinetics, preventing their accumulation in extra-tumoral tissue (especially in the liver) but only partially influencing their interaction with TAMs. Finally, anti-MMR Nb administration not only allowed the visualization of TAMs in primary tumors, but also at a distant metastatic site. Conclusions: These data describe, for the first time, a microscopic analysis of (m) and (biv)anti-MMR Nb pharmacokinetics in tumor and healthy tissues. The concepts proposed in this study provide important knowledge for the future use of Nbs as diagnostic and therapeutic agents, especially for the targeting of tumor-infiltrating immune cells.

Oral Squamous Cell Carcinoma Metastasising to Unusual Sites: A Case Series of Four Cases

Oral cancer ranks as the sixth most common malignancy worldwide, with Squamous Cell Carcinoma (SCC) being the predominant type observed in the head and neck region. Incidence and mortality rates of SCC have significantly increased over the past few decades. Smoking and tobacco chewing are the most common aetiological factors, predominantly affecting elderly males. Distant metastasis at the time of diagnosis is a rare occurrence, typically disseminating through blood vessels or lymphatics. The lungs are the most frequent site for distant metastasis, followed by bone, mediastinal nodes, and occasionally the liver. However, in our cases, we observed metastasis to uncommon sites, excluding the liver. Accurate diagnosis necessitates the correlation with clinical history, radiological, histopathological, and immunohistochemical findings. Despite employing various surgical and radiotherapeutic modalities, distant metastasis diminishes the chances of survival, successful treatment, and worsens the prognosis. This article presents four cases of oral SCC that exhibited metastasis to unusual sites. Two cases had a primary tumour in the left lateral border of the tongue, with distant metastasis to the breast and skin (chest wall), while the other two cases had a primary tumour in the left buccal mucosa and left mandibular region, with distant metastasis to the kidney and liver.

An Elusive Case of Pleural Effusion

The incidence of distant metastasis in head and neck Squamous Cell Carcinoma (SCC) is relatively low. The most frequently involved sites for distant metastasis are lungs, followed by bone and liver. The most important predictive factors for distant metastasis appear to be site of the primary tumour (hypopharynx), advanced T- and N-classification, locoregional control and histologic grade. A 61- year-old male, chronic smoker, presented with complaints of grade 4 mMRC (Modified Medical Research Council) dyspnoea. He had left-sided buccal mucosal SCC (locally advanced) and was on palliative chemotherapy. He had undergone treatment for pulmonary tuberculosis seven years back. He was tachypneic and clinical examination revealed absent breath sounds in the left hemithorax. Chest radiograph showed a massive left pleural effusion which was found to be exudative after therapeutic thoracocentesis. Cytology tests were negative for malignant cells. Positron Emission Tomography (PET) scan showed uptake along the left pleura (SUV Max-5.06) and left buccal mucosa (SUV Max -4.1). Thoracoscopic frozen section pleural biopsy revealed metastatic squamous cell carcinomatous deposits in the pleura. On table pleurodesis was done with doxycycline. The patient was continued on palliation with no recurrent effusion. However, he succumbed to the disease after eight months. This case report describes a rare case of malignant pleural effusion from a primary buccal mucosal SCC without any concurrent lung involvement.