Progressive Metastatic Disease Research Articles

Quantitative proteomics reveals serum proteome alterations during metastatic disease progression in breast cancer patients

BackgroundTumor recurrence and metastatic progression remains the leading cause for breast cancer related mortalities. However, the proteomes of patient- matched primary breast cancer (BC) and metastatic lesions have not yet been identified, due to the lack of clinically annotated longitudinal samples. In this study, we evaluated the global-proteomic landscape of BC patients with and without distant metastasis as well as compared the proteome of distant metastatic disease with its corresponding primary BC, within the same patient.MethodsWe performed mass spectrometry-based proteome profiling of 73 serum samples from 51 BC patients. Among the 51 patients with BC, 29 remained metastasis-free (henceforth called non-progressors), and 22 developed metastases (henceforth called progressors). For the 22 progressors, we obtained two samples: one collected within a year of diagnosis, and the other collected within a year before the diagnosis of metastatic disease. MS data were analyzed using intensity-based absolute quantification and normalized before differential expression analysis. Significantly differentially expressed proteins (DEPs; absolute fold-change ≥ 1.5, P-value < 0.05 and 30% abundance per clinical group) were subjected to pathway analyses.ResultsWe identified 967 proteins among 73 serum samples from patients with BC. Among these, 39 proteins were altered in serum samples at diagnosis, between progressors and non-progressors. Among these, 4 proteins were further altered when the progressors developed distant metastasis. In addition, within progressors, 20 proteins were altered in serum collected at diagnosis versus at the onset of metastasis. Pathway analysis showed that these proteins encoded pathways that describe metastasis, including epithelial–mesenchymal transition and focal adhesion that are hallmarks of metastatic cascade.ConclusionsOur results highlight the importance of examining matched samples from distant metastasis with primary BC samples collected at diagnosis to unravel subset of proteins that could be involved in BC progression in serum. This study sets the foundation for additional future investigations that could position these proteins as non-invasive markers for clinically monitoring breast cancer progression in patients.

Nerve growth factor inducible (VGF) is a secreted mediator for metastatic breast cancer tropism to the brain.

Brain metastases are one of the most serious clinical problems in breast cancer (BC) progression, associated with lower survival rates and a lack of effective therapies. Thus, to dissect the early stages of the brain metastatic process, we studied the impact of brain organotropic BC cells' secretomes on the establishment of the brain pre-metastatic niche (PMN). We found that BC cells with specific tropism to the brain caused significant blood-brain barrier (BBB) disruption, as well as microglial activation, in both in vitro and in vivo models. Further, we searched for a brain-organotropic metastatic signature, as a promising source for the discovery of new biomarkers involved in brain metastatic progression. Of relevance, we identified VGF (nerve growth factor inducible) as a key mediator in this process, also impacting the BBB and microglial functions both in vitro and in vivo. In a series of human breast tumors, VGF was found to be expressed in both cancer cells and the adjacent stroma. Importantly, VGF-positive tumors showed a significantly worse prognosis and were associated with HER2 (human epidermal growth factor receptor 2) overexpression and triple-negative molecular signatures. Further clinical validation in primary tumors from metastatic BC cases showed a significant association between VGF and the brain metastatic location, clearly and significantly impacting on the prognosis of BC patients with brain metastasis. In conclusion, our study reveals a unique secretome signature for BC with a tropism for the brain, highlighting VGF as a crucial mediator in this process. Furthermore, its specific impact as a poor prognostic predictor for BC patients with brain metastasis opens new avenues to target VGF to control the progression of brain metastatic disease. © 2024 The Pathological Society of Great Britain and Ireland.

Significance of concurrent evaluation of HER2 gene amplification and p53 and Ki67 expression in gastric cancer tissues.

The primary objective of this study is to explore the significance of concurrent evaluation of HER2 gene amplification and p53 and Ki67 expression in gastric cancer tissues. Fluorescence in situ hybridization (FISH) and immunohistochemistry (IHC) methodologies were used to detect HER2 gene amplification, as well as the expression levels of HER2, p53, and Ki67 proteins, across a group of 78 gastric cancer cases. The expression rate of the HER2 protein was determined to be 43.6% (34/78), with 17.9% (14/78) categorized as HER2 protein 3 + , 14.1% (11/78) as HER2 protein 2 + , and 11.5% (9/78) as HER2 protein 1 + . Using FISH technology, the HER2 gene amplification rate was identified as 19.2% (15/78), including 3 cases of HER2 gene cluster amplification, 5 cases of large granular amplification, 4 cases of punctate amplification, and 3 cases of high polysomy. The positive rate of p53 in gastric cancer cells was 52.6% (41/78), with 62.8% (49/78) of patients exhibiting a ki67 proliferation index ≤ 30, and 37.2% (29/78) accounting for a ki67 proliferation index > 30. The expression rates of the HER2 gene, p53, and ki67 in gastric cancer tissues were significantly associated with both gastric cancer staging and lymph node metastasis (P < 0.05). The HER2 gene amplification rate and gene copy number exhibit a positive correlation with the expression rates of p53 and ki67. Combining these assessments can provide crucial insights into the assessment of metastatic potential, disease progression, and prognosis of gastric tumor cells. This holds paramount importance in steering the formulation of individualized treatment strategies.

Efficacy and safety of lurbinectedin (LUR) with irinotecan (IRI) in patients (Pts) with relapsed small cell lung cancer (SCLC): Results from a phase 2 expansion cohort.

8094 Background: LUR has been approved in the US and elsewhere for treatment of adult pts with metastatic SCLC and disease progression on or after platinum-based chemotherapy. Preclinical studies found synergy for LUR with IRI (Galmarini C. Cancer Res 2013; 73: Abst 5499). The phase 1b/2 study PM1183-A-014-15 (NCT02611024) evaluated the LUR/IRI combination in pretreated pts with advanced solid tumors. The phase 1b part defined the recommended dose at LUR 2.0 mg/m2 on Day (D)1 + IRI 75 mg/m2 on D1,D8 every three weeks with primary G-CSF prophylaxis, and found promising results for the combination in SCLC pts after first-line therapy (Ponce Aix S. Ann Oncol 2019; 30: Abst 471P). Methods: Eligibility criteria for this cohort of the phase 2 part of this study included: confirmed SCLC, progression after one platinum-containing regimen, controlled brain metastases and ECOG PS ≤ 1. The primary endpoint was overall response rate (ORR). Results: 101 evaluable pts were enrolled. Baseline characteristics included: median age 63 (range, 45-77 y), 60.4% males, 76.2% ECOG PS 1, 28.7% CNS involvement, 39.6% bulky disease and 41.6% pretreated with immunotherapy. Chemotherapy-free interval (CTFI) was &lt;90 d in 51.4% of pts (26.7% had CTFI&lt;30 d. Median CTFI was 85 d (range, 0-323 d). Median number of cycles per pt was 6 (range, 1-34); 25.7% received &gt;10 cycles. Efficacy results by independent review committee are summarized in the table. Treatment-related adverse events (AEs) were observed in 99.0% of pts (grade ≥3 in 69.3%). Most relevant grade ≥3 events/abnormalities were neutropenia (52.5%), anemia (27.7%), diarrhea (19.8%), fatigue (18.8%), and febrile neutropenia (9.9%). Treatment-related SAEs occurred in 25.0% of pts and 5.0% discontinued due to treatment-related AEs. No treatment-related deaths occurred. Conclusions: The LUR/IRI combination showed promising antitumor activity and a manageable safety profile in these pts with poor prognosis, particularly those with CTFI&gt;30 d. These encouraging results reinforce the rationale for including this combination as an experimental arm in the ongoing pivotal phase 3 LAGOON trial (NCT05153239) in relapsed SCLC with CTFI&gt;30 d. Clinical trial information: NCT02611024 . [Table: see text]

Acquired resistance to immunotherapy and chemoradiation in MYC amplified head and neck cancer

The proto-oncogene MYC encodes a nuclear transcription factor that has an important role in a variety of cellular processes, such as cell cycle progression, proliferation, metabolism, adhesion, apoptosis, and therapeutic resistance. MYC amplification is consistently observed in aggressive forms of several solid malignancies and correlates with poor prognosis and distant metastases. While the tumorigenic effects of MYC in patients with head and neck squamous cell carcinoma (HNSCC) are well known, the molecular mechanisms by which the amplification of this gene may confer treatment resistance, especially to immune checkpoint inhibitors, remains under-investigated. Here we present a unique case of a patient with recurrent/metastatic (R/M) HNSCC who, despite initial response to nivolumab-based treatment, developed rapidly progressive metastatic disease after the acquisition of MYC amplification. We conducted comparative transcriptomic analysis of this patient’s tumor at baseline and upon progression to interrogate potential molecular processes through which MYC may confer resistance to immunotherapy and/or chemoradiation and used TCGA-HNSC dataset and an institutional cohort to further explore clinicopathologic features and key molecular networks associated with MYC amplification in HNSCC. This study highlights MYC amplification as a potential mechanism of immune checkpoint inhibitor resistance and suggest its use as a predictive biomarker and potential therapeutic target in R/M HNSCC.

Radiation enhancement using focussed ultrasound-stimulated microbubbles for breast cancer: A Phase 1 clinical trial.

Preclinical studies have demonstrated that tumour cell death can be enhanced 10- to 40-fold when radiotherapy is combined with focussed ultrasound-stimulated microbubble (FUS-MB) treatment. The acoustic exposure of microbubbles (intravascular gas microspheres) within the target volume causes bubble cavitation, which induces perturbation of tumour vasculature and activates endothelial cell apoptotic pathways responsible for the ablative effect of stereotactic body radiotherapy. Subsequent irradiation of a microbubble-sensitised tumour causes rapid increased tumour death. The study here presents the mature safety and efficacy outcomes of magnetic resonance (MR)-guided FUS-MB (MRgFUS-MB) treatment, a radioenhancement therapy for breast cancer. This prospective, single-center, single-arm Phase 1 clinical trial included patients with stages I-IV breast cancer with in situ tumours for whom breast or chest wall radiotherapy was deemed adequate by a multidisciplinary team (clinicaltrials.gov identifier: NCT04431674). Patients were excluded if they had contraindications for contrast-enhanced MR or microbubble administration. Patients underwent 2 to 3 MRgFUS-MB treatments throughout radiotherapy. An MR-coupled focussed ultrasound device operating at 800 kHz and 570 kPa peak negative pressure was used to sonicate intravenously administrated microbubbles within the MR-guided target volume. The primary outcome was acute toxicity per Common Terminology Criteria for Adverse Events (CTCAE) v5.0. Secondary outcomes were tumour response at 3 months and local control (LC). A total of 21 female patients presenting with 23 primary breast tumours were enrolled and allocated to intervention between August/2020 and November/2022. Three patients subsequently withdrew consent and, therefore, 18 patients with 20 tumours were included in the safety and LC analyses. Two patients died due to progressive metastatic disease before 3 months following treatment completion and were excluded from the tumour response analysis. The prescribed radiation doses were 20 Gy/5 fractions (40%, n = 8/20), 30 to 35 Gy/5 fractions (35%, n = 7/20), 30 to 40 Gy/10 fractions (15%, n = 3/20), and 66 Gy/33 fractions (10%, n = 2/20). The median follow-up was 9 months (range, 0.3 to 29). Radiation dermatitis was the most common acute toxicity (Grade 1 in 16/20, Grade 2 in 1/20, and Grade 3 in 2/20). One patient developed grade 1 allergic reaction possibly related to microbubbles administration. At 3 months, 18 tumours were evaluated for response: 9 exhibited complete response (50%, n = 9/18), 6 partial response (33%, n = 6/18), 2 stable disease (11%, n = 2/18), and 1 progressive disease (6%, n = 1/18). Further follow-up of responses indicated that the 6-, 12-, and 24-month LC rates were 94% (95% confidence interval [CI] [84%, 100%]), 88% (95% CI [75%, 100%]), and 76% (95% CI [54%, 100%]), respectively. The study's limitations include variable tumour sizes and dose fractionation regimens and the anticipated small sample size typical for a Phase 1 clinical trial. MRgFUS-MB is an innovative radioenhancement therapy associated with a safe profile, potentially promising responses, and durable LC. These results warrant validation in Phase 2 clinical trials. clinicaltrials.gov, identifier NCT04431674.

Machine-learning and mechanistic modeling of metastatic breast cancer after neoadjuvant treatment.

Clinical trials involving systemic neoadjuvant treatments in breast cancer aim to shrink tumors before surgery while simultaneously allowing for controlled evaluation of biomarkers, toxicity, and suppression of distant (occult) metastatic disease. Yet neoadjuvant clinical trials are rarely preceded by preclinical testing involving neoadjuvant treatment, surgery, and post-surgery monitoring of the disease. Here we used a mouse model of spontaneous metastasis occurring after surgical removal of orthotopically implanted primary tumors to develop a predictive mathematical model of neoadjuvant treatment response to sunitinib, a receptor tyrosine kinase inhibitor (RTKI). Treatment outcomes were used to validate a novel mathematical kinetics-pharmacodynamics model predictive of perioperative disease progression. Longitudinal measurements of presurgical primary tumor size and postsurgical metastatic burden were compiled using 128 mice receiving variable neoadjuvant treatment doses and schedules (released publicly at https://zenodo.org/records/10607753). A non-linear mixed-effects modeling approach quantified inter-animal variabilities in metastatic dynamics and survival, and machine-learning algorithms were applied to investigate the significance of several biomarkers at resection as predictors of individual kinetics. Biomarkers included circulating tumor- and immune-based cells (circulating tumor cells and myeloid-derived suppressor cells) as well as immunohistochemical tumor proteins (CD31 and Ki67). Our computational simulations show that neoadjuvant RTKI treatment inhibits primary tumor growth but has little efficacy in preventing (micro)-metastatic disease progression after surgery and treatment cessation. Machine learning algorithms that included support vector machines, random forests, and artificial neural networks, confirmed a lack of definitive biomarkers, which shows the value of preclinical modeling studies to identify potential failures that should be avoided clinically.

Association of a 40-Gene Expression Profile With Risk of Metastatic Disease Progression of Cutaneous Squamous Cell Carcinoma and Specification of Benefit of Adjuvant Radiation Therapy

PurposeAdjuvant radiation therapy (ART) for cutaneous squamous cell carcinoma (cSCC) is recommended based on a number of wide-ranging clinicopathologic features, which encompass a broad array of patients. The 40-gene expression profile (40-GEP) test classifies cSCC tumors into low (Class 1) or higher (Class 2A) or highest (Class 2B) risk of nodal and/or distant metastasis. This study's hypotheses are 1) local recurrence is associated with metastatic disease progression, and 2) 40-GEP, by identifying high risk for metastasis, could predict a metastasis-specific benefit from ART. MethodsSamples were obtained from 920 patients (ART-untreated: 496 Class 1, 335 Class 2A, 33 Class 2B; ART-treated: 11 Class 1, 35 Class 2A, 10 Class 2B) who were matched on clinical risk factors and stratified by ART status, to create 49 matched patient strata. To control for the variety of characteristics and treatment selection bias, randomly sampled pairs of matched ART and non-ART patients comprising 10,000 resampled cohorts were each analyzed for 5-year metastasis-free survival and predicted time to metastatic event. ResultsOf 96 patients experiencing local recurrence, 56.3% experienced metastasis; of those experiencing both, 88.9% had local recurrence before (75.9%) or concurrently (13.0%) with metastasis. After matching for clinicopathological risk, median 5-year disease progression rates for resampled cohorts demonstrated approximately 50% improvement for Class 2B ART-treated as compared to ART-untreated cohorts. Class 2B ART-treated cohorts had a 5-fold delay in predicted time to metastatic event and deceleration of disease progression as compared to ART-untreated cohorts (Kolmogorov-Smirnov test, p<0.01); this was not observed for Class 1 or 2A patients (p>0.05 for each). No risk factor or staging system combined with ART status identified groups that would benefit from ART as well as 40-GEP. Conclusion40-GEP identifies patients at highest risk of nodal/distant metastasis who may derive greatest benefit from ART, as well as patients who may have clinical indications for ART but are at low risk of metastasis. Compared to current guidelines, 40-GEP could provide greater specificity concerning the benefit of ART in individual patients.

Immunotherapy for gastrointestinal cancer

Cancers of gastrointestinal tract make up the largest group of solid tumour diseases in Germany. The prognosis at diagnosis is often critical. Drug therapies reduce the risk of relapse after resection and can halt the progression of metastatic disease. Immunotherapies contribute increasingly to the treatment of gastrointestinal tumours. Monoclonal antibodies (mAB) against surface receptors from the epidermal growth factor receptor family (EGFR, Her2) are well established. The effect is partly based on the interruption of the oncogenic downstream signalling cascades and partly on immune effector mechanisms such as antibody-dependent cellular cytotoxicity. In clinical practice mAB directed against programmed cell death protein 1 (PD-1), its ligand (PD-L1) and cytotoxic T-lymphocyte-associated protein-4 (CTLA-4) - so-called immune checkpoint inhibitors - play an increasing role and change the natural history of some subgroups of gastrointestinal cancers, especially those with deficient DNA mismatch repair which leads to genomic microsatellite instability.

Gamma knife radiosurgery following whole-brain radiation

In this study, we aimed to determine outcomes for patients requiring salvage stereotactic radiosurgery (SRS) who have progression of brain metastatic disease after initial treatment with whole-brain radiation (WBRT). This is a retrospective analysis of a prospective database of 112 patients who were treated with salvage SRS after experiencing failure following WBRT treatment with salvage SRS. Collectively, the patients had a median overall survival of 7 months after salvage SRS. Patients who had more than two brain metastases had a significantly shorter median survival but were not subjected to increased risk for distant brain failure. We also found that a short intervening time between WBRT and central nervous system (CNS) failure did not seem to worsen the nervous system control or reduce patient survival. Small cell lung cancer (SCLC) was associated with decreased overall survival and CNS control. In conclusion, SRS use following WBRT is safe and effective in the majority of patients. Patients with rapid failure after WBRT can be successfully salvaged with SRS. The findings also shed light on the overall poor outcomes, coupled with low median survival and high rates of CNS failure, in patients suffering multiple metastases stemming from SCLC.

Abstract 3572: Role of the gut microbiome in androgen production and prostate cancer treatment resistance

Abstract Metastatic prostate cancer is often treated via a combination of androgen deprivation therapy (ADT) and the androgen receptor axis-targeted therapies abiraterone acetate + prednisone (AA/P) or enzalutamide. Unfortunately, most individuals undergoing these treatments develop resistance, termed “castration resistance”, through an unknown mechanism. Previous studies demonstrate a potential link between the gut microbiota and the treatment efficacy of endocrine therapy in metastatic castration resistant prostate cancer (mCRPC). This may be due in part to gut bacterial communities with the machinery to synthesize androgens using mechanisms distinct from human cells. For example, the bacterial desAB genes (e.g., “desmolase”) that were first described in the gut commensal bacterial species Clostridium scindens convert cortisol and prednisone to the androgenic metabolites 11β-hydroxyandrost-4-ene-3,17-dione (11OHAD) and ∆1-adrenosterone (∆1-AT), respectively. We hypothesize that androgen synthesis by the gut microbiota promotes treatment resistance to AA/P in advanced prostate cancer. This study aims to determine if androgen-converting gut bacterial species as well as circulating and fecal androgen levels correlate with AA/P treatment response in individuals with mCRPC using a combination of metagenomics and metabolomics. We further aim to demonstrate the relationship between gut bacterial androgen production and prostate cancer treatment response using an in vivo mouse model. Metagenomic sequencing showed an imbalance in microbial communities and identified the presence of androgen-synthesizing bacteria such as C. scindens in fecal samples of individuals undergoing treatment with AA/P. We also demonstrate that the relative abundance of C. scindens, as well as other species reported to generate androgens, are significantly enriched during metastatic disease progression on AA/P. Furthermore, targeted quantitative PCR of the bacterial desmolase (desA) gene demonstrated that absolute levels of desmolase are significantly higher in AA/P non-responders relative to AA/P responders, and trended higher in individuals with rising prostate-specific antigen (PSA) versus stable PSA while on AA/P. Targeted LC/MS/MS analyses of fecal samples demonstrated the presence of testosterone, dihydrotestosterone, 11OHAD, ∆1-AT, and other androgen metabolites in association with rising PSA levels in the AA/P cohort. Furthermore, we demonstrate that C. scindens converts hydrocortisone and prednisone into 11OHAD and ∆1-AT, respectively, in vitro at 48- and 72h post-treatment, which recapitulates prior published studies. Finally, we have established a prostate cancer mouse model using a VCaP xenograft in which tumor growth was significantly inhibited by abiraterone acetate in comparison to treatment with ADT alone. Additional studies will use this mouse model to study the effects of androgen metabolism by gut bacteria on AA/P efficacy. Overall, this study ascertains the ability of the human gut microbiota to harbor androgen-synthesizing bacteria, which in turn can be an alternative source of androgens that could impact the efficacy of the anti-androgen therapies used to treat metastatic prostate cancer. Citation Format: Angelica I. Cruz Lebron, Pedro A. Balbuena-Almodóvar, Luke Mummert, Sarah Ernst, Mark Markowski, Michelle Rudek, Jason Ridlon, Karen S. Sfanos. Role of the gut microbiome in androgen production and prostate cancer treatment resistance [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 3572.

Abstract 4142: Obesity contributes to CD8+ T cell dysfunction before and after lung metastasis in a mouse model of ER+ breast cancer

Abstract Obesity is known to worsen the overall prognosis of breast cancer patients. Breast cancer patients with a body mass index (BMI) of ≥30 kg/m2 have an increased risk for metastatic disease compared to patients with a BMI in the normal range. Although immune cells like neutrophils and myeloid derived suppressor cells have been studied in breast cancer metastasis of the lung, little is known how T cell populations change before and after metastasis. To investigate these gaps, we fed 3-week-old female FVB/N mice either a low-fat diet (LFD) or high-fat diet (HFD) for 16 weeks to induce obesity. One group was set as a tumor-naïve control and the other was injected estrogen receptor positive (ER+) TC2 cells into the mammary fat pad. Tumors grew to 0.5 cm in diameter then were surgically removed. Lung tissue was collected 8 weeks after tumor removal to examine progression of metastatic disease, and T cell populations were quantified in tumor-naïve and metastatic lung tissue from obese and lean mice using flow cytometry. Lungs from naïve obese mice showed a significant increase of total CD45+ immune cells. CD8+ T cells from naive obese mice expressed higher levels of programmed cell death protein-1 (PD1), a marker of T cell dysfunction or T cell activation. Metastatic lungs also showed increases in CD45+ immune cells and PD-1+ expression on CD3+ cells and CD8+ cells. Overall, metastatic lungs showed higher levels of PD-1 expression than naïve lungs on more cell types, evidence of more immune dysfunction or activation. To further investigate how obesity alters the function of T cells, CD45+ cells were sorted from lungs from lean and obese mice with and without metastasis, and gene expression was examined using the NanoString nCounter Immune Exhaustion panel. Immune cells from the lungs of obese non-tumor-bearing mice showed increased expression of markers for increased TCR signaling. This may indicate more T cell activation which leads to exhaustion in obese naïve mice. In metastatic lungs from obese mice, immune cells showed impaired interferon and tumor necrosis factor signaling. In addition, immune cells from metastatic lungs of obese mice also had upregulated expression of genes associated with senescence which may indicate a combination of both exhaustion and senescent phenotypes are present. This was not seen in immune cells from naïve samples, indicating that obesity leads to more chronic T cell dysfunction in metastatic lungs. Overall, even without pathogenic interference, obesity contributes to more T cell signaling and impaired CD8+ T cell activation that leads to higher T cell dysfunction once metastasis is present. Citation Format: Abbey E. Williams, Lisa M. Arendt. Obesity contributes to CD8+ T cell dysfunction before and after lung metastasis in a mouse model of ER+ breast 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 4142.

Abstract 3585: DNA-PK inhibition to enhance radiation sensitivity in metastatic pancreatic neuroendocrine cancer

Abstract Gastroenteropancreatic (GEP) neuroendocrine tumors (NETs) are neoplasms originating from the gastrointestinal track and pancreas. Unfortunately, most patients at the time of diagnosis have extensive metastatic disease and are not candidates for curative surgical resection of metastatic tumors. In such cases, targeted radiation therapy (RT) can slow the progression of metastatic disease, but eventually tumors develop resistance to radiation therapy. In this study, we examined whether DNA-PK inhibition could sensitize pancreatic NETs to radiation therapy and enhance the radiation therapy effect in a preclinical model of pNET metastasis. Methods. We used 96-well clonogenic assays to evaluate the efficacy of the DNA-PK inhibitor peposertib in combination with RT in vitro in QGP-1 and BON pancreatic NET cell lines. Double-strand break-induced DNA repair was visualized with confocal laser scanning microscopy using γ-H2AX immunofluorescence after peposertib treatment alone or in combination with RT. Western blot analysis was used to confirm inhibition of DNA-PKcs (pDNA-PKcs S2056) combination RT. The efficacy of peposertib in combination with RT was evaluated in QGP-1 and BON human xenograft models in athymic nude mice and a BON preclinical lung metastasis model. Results. Clonogenic assays demonstrated absence of cytotoxicity from peposertib alone at doses below 1000 nM and a strong radiosensitizing effect at 200 nM in both QGP-1 and BON cell lines. Pretreatment with peposertib or treatment within 2 h after RT suppressed colony formation; treatment at later timepoints did not enhance radiotherapy. Immunofluorescence analysis revealed high numbers of γH2AX foci with peposertib therapy alone at 96 h or when given 2 h after RT. Western blot analysis confirmed inhibition of DNA-PK Ser2056 after RT in combination with peposertib. DNA-PK inhibition in combination with RT led to remarkable repression of pNET growth both in subcutaneous xenografts (&amp;gt;90%) and in the preclinical lung metastasis model (&amp;gt;90%). Conclusions. Our results showed several advantages of targeting DNA-PK to enhance radiation sensitivity in high-grade pNETs: (1) DNA-PK inhibition alone disrupts DNA damage response in pNETs as demonstrated by strong H2AX phosphorylation. (2) DNA-PK inhibition is most effective at enhancing radiotherapy either right before or after radiation therapy administration. This demonstrates that extended DNA-PK inhibition is not necessary to achieve marked responses during pNET radiotherapy. (3) DNA-PK inhibition 30 min before radiation therapy is sufficient to greatly reduce pNET tumor growth or metastasis progression in pNET preclinical models. In summary, selective DNA-PK inhibition provides a potent therapeutic strategy for disruption of non-homologous end joining DNA double-strand break repair and may offer a novel therapeutic approach in advanced NET radiotherapy. Citation Format: Piotr G. Rychahou, Aman Chauhan, Zeta Chow, Tadahide Izumi, Quan Chen, Eun Y. Lee, Dana Napier, Lowell Brian Anthony, Michael J. Cavnar, Courtney M. Townsend, B. Mark Evers. DNA-PK inhibition to enhance radiation sensitivity in metastatic pancreatic neuroendocrine 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 3585.

Quantitative peritumoral magnetic resonance imaging fingerprinting improves machine learning-based prediction of overall survival in colorectal cancer.

To investigate magnetic resonance imaging (MRI)-based peritumoral texture features as prognostic indicators of survival in patients with colorectal liver metastasis (CRLM). From 2007-2015, forty-eight patients who underwent MRI within 3 months prior to initiating treatment for CRLM were identified. Clinicobiological prognostic variables were obtained from electronic medical records. Ninety-four metastatic hepatic lesions were identified on T1-weighted post-contrast images and volumetrically segmented. A total of 112 radiomic features (shape, first-order, texture) were derived from a 10 mm region surrounding each segmented tumor. A random forest model was applied, and performance was tested by receiver operating characteristic (ROC). Kaplan-Meier analysis was utilized to generate the survival curves. Forty-eight patients (male:female = 23:25, age 55.3 years ± 18 years) were included in the study. The median lesion size was 25.73 mm (range 8.5-103.8 mm). Microsatellite instability was low in 40.4% (38/94) of tumors, with Ki-ras2 Kirsten rat sarcoma viral oncogene homolog (KRAS) mutation detected in 68 out of 94 (72%) tumors. The mean survival was 35 months ± 21 months, and local disease progression was observed in 35.5% of patients. Univariate regression analysis identified 42 texture features [8 first order, 5 gray level dependence matrix (GLDM), 5 gray level run time length matrix (GLRLM), 5 gray level size zone matrix (GLSZM), 2 neighboring gray tone difference matrix (NGTDM), and 17 gray level co-occurrence matrix (GLCM)] independently associated with metastatic disease progression (P < 0.03). The random forest model achieved an area under the curve (AUC) of 0.88. MRI-based peritumoral heterogeneity features may serve as predictive biomarkers for metastatic disease progression and patient survival in CRLM.

Atezolizumab plus personalized neoantigen vaccination (PGV001) in patients with urothelial cancer.

597 Background: Most patients (pts) with urothelial cancer (UC) treated with immune checkpoint inhibitors (ICIs) do not respond. Given that features associated with restrained antitumor immunity and high neoantigen burden have correlated with response to ICI, stimulating antitumor immunity with neoantigen vaccination is an attractive approach to overcome ICI resistance. This study assessed atezolizumab in combination with PGV001, a personalized genomic neoantigen vaccine, in the adjuvant and metastatic settings. Methods: This single-arm pilot study (NCT03359239) enrolled pts with UC for treatment in the adjuvant (≥pT3/pN+ who declined or were ineligible for adjuvant chemotherapy; or ≥ypT2/ypN+ after neoadjuvant chemotherapy) or metastatic (disease progression after chemotherapy, or “switch maintenance” for stable disease after chemotherapy) setting. Neoantigen prediction was performed using the OpenVax computational pipeline. After an initial priming vaccination course (cycle 1), pts received atezolizumab 1200 mg intravenously every 3 weeks for up to 12 months (adjuvant) or 24 months (metastatic) and PGV001 with poly-ICLC on subsequent days every 3 weeks during cycles 2-5 and 9. The primary endpoints were feasibility and safety, including the number of neoantigens identified and peptides synthesized per pt, vaccine production time, proportion of consented pts with prepared vaccine, and proportion of treatment-eligible pts completing the priming course. Secondary endpoints included immune monitoring of vaccine-induced neoantigen specific T cells. Results: Between 12/2018 and 8/2020 12 pts were enrolled. The median neoantigens identified per pt was 103 (range 60-388). Vaccines containing 9-10 synthetic long peptides (24-25mer) were prepared for 92% (11/12) of consented pts over a median of 153 days (95% CI 151-181 days). 100% (10/10: 4 adjuvant, 6 metastatic) of pts eligible for the treatment phase completed the priming course. All evaluated pts demonstrated the emergence of ex vivo T cell responses as reflected by IFNγ production, including circulating multi-functional CD4+ and CD8+ neoantigen-specific T cell responses upon expansion. At a median follow up of 32 months, 4/4 patients treated in the adjuvant setting were free of recurrence and 2/5 pts with metastatic UC achieved an objective response. The single pt treated in the switch maintenance setting had no evidence of disease, off all treatment, at 33 months. The most common treatment-related adverse events were grade 1 injection site reactions, fatigue, and fever. One pt developed grade 3 immune-related hepatitis. Conclusions: Atezolizumab plus PGV001 was feasible, safe, and induced neoantigen-specific T cell immunity in all evaluated pts. To our knowledge, this is the first report of combination neoantigen vaccination plus ICI in the adjuvant setting in UC. Neoantigen vaccination plus ICI warrants further evaluation. Clinical trial information: NCT03359239 .

Association of a 40-Gene Expression Profile (40-GEP) with Risk of Metastatic Disease Progression of Cutaneous Squamous Cell Carcinoma (cSCC) and Benefit of Adjuvant Radiation Therapy (ART)

Purpose: Adjuvant radiation therapy (ART) is recommended based on high-risk clinicopathologic features of cutaneous squamous cell carcinoma (cSCC), but these criteria are wide-ranging, encompassing a broad range of patients. The 40-gene expression profile (40-GEP) test is a prognostic tool which classifies cSCC tumors into low (Class 1), moderate (Class 2A), and high (Class 2B) risk of metastasis. This study determined if the metastatic risk as assessed by 40-GEP in high-risk cSCC patients predicts benefit from ART. Study: Samples were obtained from 920 patients who were matched on clinical risk factors and stratified by ART status, to create 49 matched patient strata. Randomly sampled pairs of matched ART and non-ART patients comprising 10,000 resampled cohorts were each analyzed for 5-year metastasis-free survival (nodal and/or distant events; MFS) and predicted time to metastatic event (using a standard ‘life expectancy’ algorithm). Results: Median 5-year MFS rates for the resampled cohorts demonstrated a 50% improvement, on average, for Class 2B ART-treated patient cohorts compared to Class 2B non-ART-treated patient cohorts. Class 2B ART-treated patient cohorts showed a 5-fold delay in predicted time to metastatic event and a deceleration of disease progression as compared to non-ART-treated patients (Kolmogorov-Smirnov test, p&lt;0.01), that was not observed for Class 1 or 2A patients (p&gt;0.05 for each). No risk factor or staging system combined with ART status was able to identify groups that would benefit from ART treatment as well as the 40-GEP test. Conclusions: The 40-GEP test identifies patients at highest risk of nodal or distant metastasis who are most likely to benefit from ART, as well as lower-risk cohorts who benefit less from ART. These findings provide greater specificity than current clinicopathologic guidelines on which to base decisions for ART.

A Case of Rapidly Progressive De Novo Metastatic Small‐Cell Neuroendocrine Prostate Cancer

Introduction: Neuroendocrine/small‐cell prostate cancer (NEPC) is a rare and aggressive subtype of prostate cancer, which typically develops after prolonged treatment for metastatic castration‐resistant disease, but can, less commonly, occur de novo.Case Presentation: We describe a case of de novo NEPC in a tumor with mixed pathology including acinar adenocarcinoma and neuroendocrine/small‐cell carcinoma with rapid progression of metastatic disease. Despite initiation of treatment with androgen deprivation therapy (ADT) and chemotherapy, the patient continued to exhibit progression leading to multiple complications including a large bowel obstruction and ultimately progressive hepatic metastases resulting in liver failure.Conclusion: This case illustrates the clinical presentation and highly aggressive nature of de novo NEPC. Recognizing atypical clinical progression in prostate cancer is critical for the detection of NEPC; however, despite early identification and initiation of treatment, the prognosis remains poor, thus highlighting the need for further study into NEPC biology and novel therapeutic approaches.

NCMP-21. AQP4-MOG DOUBLE-POSITIVE PARANEOPLASTIC NEUROLOGICAL SYNDROME IN A PATIENT WITH TRIPLE NEGATIVE BREAST CANCER

Abstract We report a rare case of paraneoplastic neurological syndrome (PNS) with dual seropositivity of anti-aquaporin-4 (AQP-4) and myelin oligodendrocyte glycoprotein (MOG) antibodies in a 40 year-old lady with metastatic triple negative breast cancer with involvement of mediastinal, right axillary, and supraclavicular lymph nodes. She received multiple lines of anti-neoplastic treatment including immunotherapy with pembrolizumab as well as chemotherapy with taxol, carboplatin, gemcitabine, capecitabine, cytoxan, sacituzumab and nevalbine. Paraneoplastic meningoencephalomyelitis developed 2 years after diagnosis of breast cancer and 1 year after discontinuation of immunotherapy with pembrolizumab. She first developed longitudinally extending transverse myelitis extending from T11-12 that symptomatically improved with high dose intravenous methylprednisolone. One month later she developed left optic neuritis and meningoencephalitis with new enhancing lesions in the brain and spinal leptomeninges. Cerebrospinal fluid (CSF) analysis during both episodes revealed normal glucose, protein, elevated white blood cell count. Cytology was negative for malignancy. CSF was positive for neuromyelitis optica (NMO) IgG antibody APQ-4 and autoimmune myelopathy panel was positive for MOG antibody. Patient had significant clinical and radiographic improvement after completion of plasmapheresis and intravenous immunoglobulin. There was resolution of pleocytosis on repeat CSF testing. She did not have recurrence of paraneoplastic syndrome with maintenance rituximab every six months and daily low dose prednisone. She succumbed to progressive systemic metastatic disease 4.5 years after her breast cancer diagnosis. This case demonstrates that these antibodies can occur concurrently and cause clinical features like both neuromyelitis optica spectrum disorder (NMOSD) and myelin oligodendrocyte glycoprotein antibody disease (MOGAD) in a patient with a singular type of cancer. We highlight the importance of testing for paraneoplastic etiology in cancer patients with radiographic menigoencephalomyelitis or meningitis with atypical symptoms of meningeal carcinomatosis and/or CSF profile negative for leptomeningeal carcinomatosis.

CTNI-11. THE VALUE OF STEREOTACTIC BIOPSY OF PRIMARY AND RECURRENT BRAIN METASTASES IN THE ERA OFPRECISION MEDICINE

Abstract BACKGROUND: Brain metastases (BM) represent the most frequent intracranial tumors with increasing incidence. Many primary tumors are currently treated in protocols that incorporate targeted therapies either upfront or for progressive metastatic disease. In cases with diagnostic uncertainty, both in newly diagnosed or recurrent BM, stereotactic biopsy serves as an alternative to microsurgical resection particularly whenever resection is not deemed to be safe or feasible. This retrospective study aimed to analyze both diagnostic yield and safety of an image-guided frame based stereotactic biopsy technique (STX).

Leptomeningeal Metastases in Carcinoma Rectum with Extensive Skeletal Metastasis - A Case Report

Incidence of rectal carcinoma has been rising in younger people in recent decades. Skeletal metastasis without other organ metastasis from primary rectal carcinoma is very rare, spine and the pelvis are the first sites of bony metastasis. Leptomeningeal Metastases (LM) is a very rare complication of solid tumour progression and its incidence in colorectal carcinoma is far less. A nineteen-year-old male presented in the OPD with rectal bleeding and low back pain with colonoscopic biopsy proving rectal carcinoma. MRI of pelvis revealed multiple osseous metastases to vertebrae and pelvic bones. After four cycles of palliative chemotherapy, he developed lower back pain. Repeat MRI revealed multiple lesions in the vertebrae and long bones for which he received palliative external beam radiation therapy (EBRT). Subsequently seven months later he developed meningeal metastases and received whole brain radiation and supportive care. LM in patients with primary colorectal cancer (CRC) remains an exceedingly rare complication of metastatic disease progression in CRC.&#x0D; Colorectal cancer (CRC) is the third most common cancer diagnosed in both men and women.[1] The incidence of it has been rising in young adults.[2] The common metastatic sites of CRC include the liver (57.6%), abdominal lymph nodes (48.3%), lungs (37.6%) and Peritoneum.[3,4,5] Skeletal metastasis without other organ metastasis is very rare. Bone metastasis is seen in 4.7% to 10.9% in clinical cases and often indicates advanced disease with a poor prognosis with 5-year survival rate less than 5%,[6] leading to significantly high rate of morbidity and mortality.&#x0D; Leptomeningeal Metastases (LM) or neoplastic meningitis, is an uncommon metastatic complication of solid tumour progression. Most commonly arising from breast, non-small-cell lung cancer, and melanoma with a frequency of 5% to 25%.[7] The incidence of LM in colorectal cancer (CRC) is far less than 1%.[8]&#x0D; Here we report a case of rectal carcinoma, with extensive skeletal metastases and their pattern of bone involvement, who later presented with meningeal metastases.