Metastatic Neuroendocrine Cancer Research Articles

Identification and In Vivo Validation of Unique Anti-Oncogenic Mechanisms Involving Protein Kinase Signaling and Autophagy Mediated by the Investigational Agent PV-10.

PV-10 is a 10% formulation of rose bengal sodium that has potent immunotherapeutic and anti-cancer activity against various tumors, including metastatic melanoma and refractory neuroblastoma. Currently, PV-10 is undergoing clinical testing for refractory metastatic neuroendocrine cancer and melanomas. However, preclinical investigation of PV-10 activity and its mechanisms against phenotypically and molecularly diverse adult solid tumors had not been conducted. In a panel of human cell lines derived from breast, colorectal, head and neck, and testicular cancers, we demonstrated that PV-10 induces cytotoxicity by apoptotic and autophagic pathways involving caspase-mediated PARP cleavage, downregulation of SQSTM1/p62, and upregulation of beclin-1. Treatment with PV-10 also consistently reduced phosphorylation of WNK1, which has been implicated in cancer cell migration and autophagy inhibition. By wound healing assay, PV-10 treatment inhibited the migration of cancer cells. Finally, significant inhibition of tumor growth was also noted in tumor-bearing mice treated with PV-10 by intralesional or systemic administration. In addition to known PV-10-mediated tumor-specific cytotoxic effects, we identified the mechanisms of PV-10 and provide new insights into its effect on autophagy and metastasis. Our data provide essential mechanism-based evidence and biomarkers of activity to formulate clinical studies of PV-10 in the future.

Polyomavirus-positive Merkel cell carcinoma: the beginning of the beginning.

Merkel cell carcinoma (MCC) is an aggressive, fast-growing, highly metastatic neuroendocrine skin cancer. The Merkel cell polyomavirus (MCPyV) is an oncogenic driver in the majority of MCC tumors. In this issue of the JCI, Hansen and authors report on their tracking of CD8+ T cells reactive to MCPyV T antigen (T-Ag) in the peripheral blood of 26 patients with MCC who were undergoing frontline anti-programmed cell death protein-1 (anti-PD-1) immunotherapy. They discovered unique T cell epitopes and used the power of bar-coded tetramers to portray immune checkpoint inhibitor-induced immunogenicity as a predictor of clinical response. These findings provide the foundation for therapeutic possibilities for MCC, including vaccines and adoptive T cell- and T cell receptor-driven (TCR-driven) treatments.

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 (>90%) and in the preclinical lung metastasis model (>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.

Which cancer? Clinical decision making in a case of concurrent metastatic neuroendocrine tumour and breast cancer

Which cancer? Clinical decision making in a case of concurrent metastatic neuroendocrine tumour and breast cancer

Retifanlimab: a breakthrough for the management of Merkel cell carcinoma

Merkel cell carcinoma (MCC) is a rare, highly metastatic cutaneous neuroendocrine cancer originating from specialized Merkel cells, which are responsible for touch sensation in the skin. It is characterized by a firm, rapidly expanding nodule on sun-exposed skin areas, especially the head and neck. It has a high mortality rate, with reported overall survival rates ranging from 14% for distant disease to 51% for local disease. In March 2023, retifanlimab (Zynyz) received accelerated U.S. Food and Drug Administration (FDA) approval for treating adults with metastatic or recurrent locally advanced MCC. This drug offers a first-line response against MCC by improving the body’s immune response against cancer cells. This article aims to provide updated guidelines on the properties, dosing, and mechanism of action while discussing its use for the management of adults.

Chemotherapy efficacy in metastatic neuroendocrine colorectal cancer

AIM: to evaluate the effectiveness of first-line chemotherapy in patients with colorectal neuroendocrine cancer (NEC).PATIENTS AND METHODS: a retrospective study included patients with metastatic colorectal NEC (2000-2020). The main analyzed parameter was the response rate to treatment according to the RECIST criteria, depending on the regimen used in the first line. The overall survival was additional parameter.RESULTS: the study included 27 patients (13 with initial stage IV disease and 14 with progression after primary radical treatment). Ten patients in the 1st line underwent chemotherapy according to the EP scheme, 4 — XELOX, 2 — FOLFIRI, 2 — Irinotecan and Cisplatin, 1 — Samarium, 1 — Nivolumab, 1 — 5-FU-LV. Most often, the treatment effect (partial response or stabilization) was observed against the background of chemotherapy according to the EP scheme — in 60% of patients. The median OS was 7 months.CONCLUSION: the use of chemotherapy according to the EP regimen is the preferred options for the treatment of metastatic colorectal NEC. The median OS in this group of patients remains extremely low, and new clinical trials are needed.

Therapeutic blocking of VEGF binding to neuropilin-2 diminishes PD-L1 expression to activate antitumor immunity in prostate cancer.

Prostate cancers are largely unresponsive to immune checkpoint inhibitors (ICIs), and there is strong evidence that programmed death-ligand 1 (PD-L1) expression itself must be inhibited to activate antitumor immunity. Here, we report that neuropilin-2 (NRP2), which functions as a vascular endothelial growth factor (VEGF) receptor on tumor cells, is an attractive target to activate antitumor immunity in prostate cancer because VEGF-NRP2 signaling sustains PD-L1 expression. NRP2 depletion increased T cell activation in vitro. In a syngeneic model of prostate cancer that is resistant to ICI, inhibition of the binding of VEGF to NRP2 using a mouse-specific anti-NRP2 monoclonal antibody (mAb) resulted in necrosis and tumor regression compared with both an anti-PD-L1 mAb and control immunoglobulin G.This therapy also decreased tumor PD-L1 expression and increased immune cell infiltration. We observed that the NRP2, VEGFA, and VEGFC genes are amplified in metastatic castration-resistant and neuroendocrine prostate cancer. We also found that individuals with NRP2High PD-L1High metastatic tumors had lower androgen receptor expression and higher neuroendocrine prostate cancer scores than other individuals with prostate cancer. In organoids derived from patients with neuroendocrine prostate cancer, therapeutic inhibition of VEGF binding to NRP2 using a high-affinity humanized mAb suitable for clinical use also diminished PD-L1 expression and caused a substantial increase in immune-mediated tumor cell killing, consistent with the animal studies. These findings provide justification for the initiation of clinical trials using this function-blocking NRP2 mAb in prostate cancer, especially for patients with aggressive disease.

Abstract 4504: Targeting cMYC in metastatic castration resistant and neuroendocrine prostate cancer

Abstract Prostate cancer is the most common cancer in men and the second leading cause of cancer death among men in the United States according to the National Cancer Institute. Current treatment modalities involve prostatectomy, androgen receptor blockade and supportive/palliative care. Despite these treatment options, metastatic castration resistant prostate cancer and neuroendocrine prostate cancer still have very dismal clinical outcomes. Therefore, there is a need to understand the biology of the aggressive prostate cancer subtypes to identify novel targetable molecules. The castration resistant prostate cancer, neuroendocrine prostate cancer and the metastatic prostate cancers that recur have c-MYC amplification. These cancers are not responsive to androgen blockade or deprivation therapy. Attempts to target c-MYC have been difficult due to the intrinsic disordered nature of c-MYC. Various approaches have been attempted to control c-MYC; namely RNAi which has high off target effects, anti-sense oligonucleotides (ASO) which have low cellular penetrance and needs phosphorothioate modification, G-quadruplex inhibitors which are unspecific as they block POLII, the BRD4 and CDK inhibitors which are indirect inhibitors of c-MYC. Only OmoMyc a bHLH domain mutant with enhanced leucine zipper dimerization is in phase 1 trials with limited bioavailability. To explore the possibility of targeting c-MYC in these difficult-to-treat prostate cancers, we transfected C4-2B, a cellular model of metastatic castration resistant prostate cancer, with engineered destabilized 3‘UTR AU rich element of c-MYC. We found that we degraded c-MYC transcript and protein and killed the cancer cells. Taken together, we offer preliminary evidence that we can directly target c-MYC and inhibit these difficult-to-treat cancers. In vivo studies to validate these findings are ongoing. Citation Format: Chidiebere U. Awah, Olorunseun O. Ogunwobi. Targeting cMYC in metastatic castration resistant and neuroendocrine prostate cancer. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 4504.

Abstract 5661: Pre-clinical development of a dopamine receptor 2, PD-1, and CD47 trispecific antibody for the treatment of solid tumors

Abstract Multispecific antibodies can have multiple independent mechanisms of action to achieve better clinical outcomes in cancers with high unmet medical needs. Here we describe the preclinical development of a trispecific antibody (KJ-101) targeting dopamine receptor 2 (DRD2), PD-1, and CD47. DRD2 is a G protein-coupled receptor upregulated in many cancer types where it correlates with decreased patient survival. In pre-clinical studies, DRD2 is associated with cancer cell stemness and tumor growth. Clinical responses were achieved with small molecules targeting DRD2 and dopaminergic drugs for neuroendocrine tumors. In SCLC, representing 15% of lung cancers, 60-70% of patients showed high expression of DRD2. Checkpoint inhibition has shown some efficacy in lung cancer where PD-L1 inhibitors were approved as first-line therapy in SCLC. SCLC patients rapidly fail chemotherapy, develop resistance to treatment and metastases. These observations suggest a link between DRD2 expression and resistance to treatment, making this receptor an attractive target for multispecific antibody therapy. The VHH components of KJ-101 (anti-DRD2, anti-PD-1 and anti-CD47) produce multiple effects to achieve a strong anti-tumor activity. The anti-DRD2 VHH induces intracellular signaling and suppresses tumor growth via ADCC. Treatment with anti-DRD2 antibody significantly suppressed tumor growth in the DRD2-positive NCI-H510A SCLC model in SCID mice. The anti-PD-1 VHH restores T cell function, and the anti-CD47 VHH recruits T cells without their generalized activation and blocks the interaction between CD47 and SIRPα. The KJ-101 anti-tumor efficacy was tested in several in vivo immuno-oncology xenograft models of human SCLC or TNBC, reconstituted with human PBMC or with CD34+ hemopoietic stem cells. KJ-101 treatment led to tumor regression in the TNBC model, blocked metastases formation in CD34+ humanized NCG mice bearing established NCI-H69 tumors, and blocked metastases formation and increased survival in tail vein metastatic models of SCLC. KJ-101 is produced at a high yield (6 g/L) in a manufacturing cell line. Conventional purification yields 99% purity and notably displays high stability under accelerated stability testing. In conclusion, the trispecific KJ-101 antibody has strong in vivo anti-tumor activity mediated via multiple mechanisms of action, is easily expressed and purified, and is very stable. Together, this data supports the clinical development of KJ-101 in advanced metastatic neuroendocrine cancer indications, including SCLC. Citation Format: Shugang Yao, Hiba Zahreddine, Dominic Hou, Elijus Undzys, Liying Gong, Richard Wargachuk, Xiaowei Wang, Alex Zhou, Lucy Lai, Luis A. Da Cruz, David Young. Pre-clinical development of a dopamine receptor 2, PD-1, and CD47 trispecific antibody for the treatment of solid tumors. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5661.

Prognostic Evaluation of Metastatic Castration Resistant Prostate Cancer and Neuroendocrine Prostate Cancer with [68Ga]Ga DOTATATE PET-CT.

Objectives: Prostate cancer is well known to express high levels of somatostatin receptors and preliminary data suggests that PET imaging with the somatostatin analog, [68Ga]Ga-DOTATATE, may allow for whole body staging of patients with metastatic castration resistant prostate cancer (mCRPC) and neuroendocrine prostate cancer (NePC). This study explores the utility of [68Ga]Ga-DOTATATE PET-CT to identify metastatic deposits in men with mCRPC and NePC and prognosticate disease progression. Methods: [68Ga]Ga-DOTATATE PET-CT was performed in 17 patients with mCRPC and of those, 2/17 had NePC. A semiquantitative analysis with standardized uptake values (SUV) (e.g., SUVmax, SUVmean) was performed for each metastatic lesion and reference background tissues. [68Ga]Ga-DOTATATE uptake in metastatic deposits was further classified as: mild (less than liver), moderate (up to liver average), or marked (greater than liver). Serial prostate-specific antigen measurements and patient survival were followed up to 3 years after PET imaging to assess response to standard of care treatment. Results: All patients had at least one metastatic lesion with identifiable [68Ga]Ga-DOTATATE uptake. Marked [68Ga]Ga-DOTATATE uptake was found in 7/17 patients, including both NePC patients, and all were non-responders to systemic therapy and died within the follow up period, with a mean time to death of 8.1 months. Three patients had mild [68Ga]Ga-DOTATATE uptake, and all were responders to systemic therapy and were alive 36 months after [68Ga]Ga-DOTATATE imaging. Conclusions: [68Ga]Ga-DOTATATE is able to identify mCRPC and NePC metastatic deposits, and lesions with [68Ga]Ga-DOTATATE uptake > liver may portend poor outcomes in patients with mCRPC.

LBODP064 A Rare Case Of Paraneoplastic Cushing Syndrome Associated With Pulmonary Carcinoid Tumor

Abstract A 67-year-old female with a history of primary pulmonary carcinoid tumor with metastasis to the liver presented with shortness of breath and generalized weakness. On presentation, her vital signs were BP 170/100 mm Hg, pulse 99/min, RR 18/min, O2 saturation 85% on room air. Physical exam was significant for diffuse rhonchi in bilateral lungs. Initial labs showed marked hypokalemia with K+ 2.5 and HCO3- 42. CT scans showed increased numbers of nodules and sizes in the lungs and numerous large liver masses. The adrenal glands and aldosterone-to-renin ratio were within normal limits. A random cortisol level was 113.14 ug/dL (2.50-12.50) with a concomitant elevated ACTH level of 353.6 pg/mL (7.2-63.3), while brain MRI was negative for pituitary or metastatic lesion. A liver mass biopsy revealed a transformation into a high-grade neuroendocrine tumor with a Ki-67 of 32%. A low dose dexamethasone suppression test showed a cortisol level of 66. 08. Interpreting this result and the imaging studies, it was determined that hypercortisolism was secondary to ectopic ACTH production. This clinical presentation and findings supported her cancer transformation to a functional metastatic neuroendocrine cancer with a paraneoplastic syndrome previously unknown. She was started on spironolactone as a potassium-sparing diuretic, itraconazole to inhibit cortisol synthesis based on inpatient formulary at that time, and combination chemotherapy with cisplatin and etoposide. Over the next few weeks, she developed signs of Cushing syndrome with leg swelling, facial puffiness, proximal muscle weakness, muscle loss, easy bruising, abdominal striae, coccydynia, glucose intolerance, and acid reflux. She had complications of peptic ulcer disease with bleeding, Clostridium difficile colitis, bacterial pneumonia, persistent hypokalemia, hypomagnesemia, and chemotherapy-induced anemia and severe thrombocytopenia. A repeat cortisol level was >150. 00 ug/dL despite the uptritation of itraconazole, suggesting not so much success. With insurance approval, she was started on ketoconazole, on which the cortisol levels on Days 5, 12, and 19 were 114.74 ug/dL, 126.84 ug/dL, and 118.42 ug/dL, respectively. Given uncontrolled hypercortisolism, a novel cortisol synthesis inhibitor, osilodrostat, was ordered and approved. However, two days later, the patient required another hospitalization for respiratory failure and severe sepsis from Coronavirus Disease 2019 pneumonia and Acinetobacter radioresistens bacteremia, and she passed away. This case highlights the therapeutic challenge of managing a late presentation of Cushing syndrome from ectopic ACTH production secondary to the progression of metastatic lung cancer. As such, clinicians should periodically consider screening for the subclinical-Cushing syndrome to diagnose such cases early, preventing such consequences of overt Cushing syndrome. Presentation: No date and time listed

Abstract 1121: Identification and in vivo validation of unique anti-oncogenic properties and mechanisms involving protein kinase signalling and autophagy mediated by the investigational new agent PV-10

Abstract Introduction: PV-10 (10% Rose Bengal) is a small molecule agent previously shown to have potent immunotherapeutic and anti-tumor activities against a number of tumors including metastatic melanoma and refractory neuroblastoma, and is currently undergoing clinical testing as a single-agent for refractory metastatic neuroendocrine cancer (NCT02693067) and in combination with checkpoint inhibitors for metastatic melanoma (NCT02557321) and metastatic uveal melanoma (NCT00986661). We have previously determined that PV-10 induces cell death at pharmacologically relevant concentrations in a panel of phenotypically diverse adult solid tumor cell lines. However, the molecular consequences of this phenomenon have not yet been fully elucidated. In this study, we investigated the target validation and modulation of PV-10 on protein kinase signalling and their associated impact on specific oncogenic pathways in these tumor cells. Methods: A panel of human tumor cell lines derived from breast (MCF-7, T-47D, MDA-MB-231), colorectal (LoVo, T-84), head and neck (CAL-27, Detroit-562, FaDu, UM-SCC-1), and testicular (NCC-IT, NTERA-2, TCAM-2) tissues were treated with PV-10 and their cytotoxic and pro-apoptotic effects were described. Protein kinase profiling was performed using the human phospho-kinase antibody array (#ARY003C, R&D Systems). Western blotting was used to investigate autophagic markers and protein kinase activity. Cell migration inhibition was determined by wound healing assay following treatment with a sublethal dose of PV-10 or pan-WNK inhibitor WNK463. Tumor xenograft studies were carried out according to established protocols. Results: Treatment with PV-10 leads to consistent inhibition of WNK lysine deficient protein kinase 1 (WNK1) phosphorylation based on protein kinase profiling of drug-treated cancer cells when compared with vehicle-treated cells. WNK1 has been implicated as an inhibitor of autophagy and a promoter of cell migration and invasion in several cancers. Western blot analysis showed that PV-10 leads to the downregulation of SQSTM1/p62, upregulation of Beclin-1, and conversion of LC3B-I into LC3B-II, indicating activation of autophagy. PV-10 was also found to significantly inhibit the migration of cancer cells similar to the inhibitor WNK463. Significant tumor regression and target modulation was noted in tumor-bearing animals treated with PV-10. Conclusion: In addition to the known activity of PV-10 to mediate tumor-specific immune responses and cytotoxic effects in neoplasms, we have identified novel therapeutic targets for PV-10, such as WNK1, and provide new insights into its effect on autophagy and metastasis. Our data provide essential mechanism-based evidence and biomarkers of activity to formulate effective PV-10 backbone clinical studies in the future. Citation Format: Son Tran, Satbir Thakur, Mohit Jain, Chunfen Zhang, Aru Narendran. Identification and in vivo validation of unique anti-oncogenic properties and mechanisms involving protein kinase signalling and autophagy mediated by the investigational new agent PV-10 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1121.

The Andrographolide Analogue 3A.1 Synergizes with Taxane Derivatives in Aggressive Metastatic Prostate Cancers by Upregulation of Heat Shock Proteins and Downregulation of MAT2A-Mediated Cell Migration and Invasion.

Conventional treatment with taxanes (docetaxel-DTX or cabazitaxel-CBZ) increases the survival rates of patients with aggressive metastatic castration-resistant prostate cancer (mCRPC); however, most patients acquire resistance to taxanes. The andrographolide analog, 19-tert-butyldiphenylsilyl-8,7-epoxy andrographolide (3A.1), has shown anticancer activity against various cancers. In this study, we investigated the effect of 3A.1 alone and in combination with DTX/CBZ against mCRPC and their mechanism of action. Exposure to 3A.1 alone exhibited a dose- and time-dependent antitumor activity in mCRPC. Chou-Talalay's combination index (CI) values of all 3A.1 + TX combinations were less than 0.5, indicating synergism. Co-treatment of 3A.1 with TX reduced the required dose of DTX and CBZ (P < 0.05). Caspase assay (apoptosis) results concurred with in vitro cytotoxicity data. RNA sequencing (RNAseq), followed by ingenuity pathway analysis (IPA), identified that upregulation of heat-shock proteins (Hsp70, Hsp40, Hsp27, and Hsp90) and downregulation of MAT2A as the key player for 3A.1 response. Furthermore, the top treatment-induced differentially expressed genes (DEGs) belong to DNA damage, cell migration, hypoxia, autophagy (MMP1, MMP9, HIF-1α, Bag-3, H2AX, HMOX1, PSRC1), and cancer progression pathways. Most importantly, top downregulated DEG MAT2A has earlier been shown to be involved in cell migration and invasion. Furthermore, using in silico analysis on the Cancer Genome Atlas (TCGA) database, this study found that MAT2A and highly co-expressed (r > 0.7) genes, TRA2B and SF1, were associated with worse Gleason score and nodal metastasis status in prostate adenocarcinoma patients (PRAD-TCGA). Immunoblotting, comet, and migration assays corroborated these findings. These results suggest that 3A.1 may be useful in increasing the anticancer efficacy of taxanes to treat aggressive PCa. SIGNIFICANCE STATEMENT: The andrographolide analogue, 19-tert-butyldiphenylsilyl-8,7-epoxy andrographolide (3A.1), showed anticancer activity against metastatic castration-resistant and neuroendocrine variant prostate cancers (mCRPC/NEPC). Additionally, 3A.1 exhibited synergistic anticancer effect in combination with standard chemotherapy drugs docetaxel and cabazitaxel in mCRPC/NEPC. Post-treatment gene expression studies revealed that heat shock proteins (Hsp70, Hsp40, Hsp27, and Hsp90) and MAT2A are important in the mechanism of 3A.1 action and drug response. Furthermore, DNA damage, cell migration, hypoxia, and autophagy were crucial pathways for the anticancer activity of 3A.1.

177Lu-dotatate use in chronic kidney disease patients: A single center experience

Background: Peptide receptor radionuclide therapy with 177Lu-dotatate is a novel therapy for metastatic neuroendocrine cancers. It undergoes reabsorption at the proximal tubule; after the breakdown of the peptide fragment, 177Lu is retained and continues its decay process exposing the nephron to continuous low dose radiation. Pivotal NETTER-1 trial did not include patients with eGFR &lt;50 and so its effects in CKD patients is not known. Methods: We performed a retrospective chart review of all consecutive adult patients that received 177Lu-dotatate over 1 year at Mayo Clinic, Rochester. We analyzed renal and hematological laboratory data obtained prior to each of four treatment cycles and at 3- and 6-month post completion of all treatment. We defined CKD as eGFR &lt;60 ml/min and AKI as creatinine increase of ⩾0.3 from baseline by AKIN criteria. Results: Overall 86 patients were included in the study with 39 (45%) with known CKD. About three patients had CKD, four with eGFR of 20–30 ml/min. About 4 (4.6%) patients had AKI and the predominant cause being hypotension. Among the CKD patients the average eGFR improved after the first cycle of PRRT therapy from baseline of 49 (13) to 53.5 (17) ml/min ( p = 0.01) with no significant decline of renal function noted at 3- and 6-months post treatment follow up. Rate of thrombocytopenia and leukopenia were significantly more in the CKD patients starting even after single treatment. No drug dose correlation was noted. Conclusion: Patients with CKD are at a higher risk of hematological toxicity especially with thrombocytopenia and require close monitoring and ongoing dose adjustment. Ongoing safety studies to assess the long-term impact of 177Lu-dotatate on the kidney are needed.

ZNF507 affects TGF-\u03b2 signaling via TGFBR1 and MAP3K8 activation in the progression of prostate cancer to an aggressive state

BackgroundThe progression of prostate cancer (PC) to the highly aggressive metastatic castration-resistant prostate cancer (mCRPC) or neuroendocrine prostate cancer (NEPC) is a fatal condition and the underlying molecular mechanisms are poorly understood. Here, we identified the novel transcriptional factor ZNF507 as a key mediator in the progression of PC to an aggressive state.MethodsWe analyzed ZNF507 expression in the data from various human PC database and high-grade PC patient samples. By establishment of ZNF507 knockdown and overexpression human PC cell lines, we assessed in vitro PC phenotype changes including cell proliferation, survival, migration and invasion. By performing microarray with ZNF507 knockdown PC cells, we profiled the gene clusters affected by ZNF507 knockdown. Moreover, ZNF507 regulated key signal was evaluated by dual-luciferase reporter and chromatin immunoprecipitation (ChIP) assays. Finally, we performed xenograft and in vivo metastasis assay to confirm the effect of ZNF507 knockdown in PC cells.ResultsWe found that ZNF507 expression was increased, particularly in the highly graded PC. ZNF507 was also found to be associated with metastatic PC of a high grade. Loss- or gain-of-function–based analysis revealed that ZNF507 promotes the growth, survival, proliferation, and metastatic properties of PC (e.g., epithelial-mesenchymal transition) by upregulating TGF-β signaling. Profiling of gene clusters affected by ZNF507 knockdown revealed that ZNF507 positively regulated the transcription of TGFBR1, MAP3K8, and FURIN, which in turn promoted the progression of PC to highly metastatic and aggressive state.ConclusionsOur findings suggest that ZNF507 is a novel key regulator of TGF-β signaling in the progression of malignant PC and could be a promising target for studying the development of advanced metastatic PCs.

Pre-clinical evaluation of PV-10 for in vitro anti-tumor activity in refractory and high-risk adult solid tumors.

e14544 Background: PV-10 (10% rose bengal disodium; 4,5,6,7-tetrachloro-2’,4’,5’,7’-tetraiodofluorescein) is a novel therapeutic agent previously shown to have potent anti-tumor activity following intratumoral injection in melanoma and refractory neuroblastoma, and currently is undergoing clinical testing as a single-agent for refractory metastatic neuroendocrine cancer (NCT02693067) and in combination with checkpoint inhibitors for metastatic melanoma (NCT02557321) and metastatic uveal melanoma (NCT00986661). Given the established clinical efficacy of PV-10 in adult melanoma and hepatic cancers via intratumoral injection, there is a need to evaluate the therapeutic potential of PV-10 in high-risk and refractory adult solid tumors via systemic administration. Our study aims to identify the clinical potential of systemically-delivered PV-10 by first generating prerequisite in vitro data for adult malignancies. Methods: Cytotoxicity assays were performed using the Alamar Blue assay to study the effects of PV-10 in vitro 96-hours post-treatment against a panel of adult solid tumor cell lines derived from breast (MCF-7, T-47D, MDA-MB-231), colorectal (HCT-116, LoVo, T-84), head and neck (CAL-27, Detroit-562, FaDu, UM-SCC-1), and testicular (NCC-IT, NTERA-2, TCAM-2) tissues. Light microscopy and Western blotting were used to investigate apoptosis induction and target modulation in tumor cells after PV-10 treatment. Results: In vitro results from our study demonstrate that PV-10 is cytotoxic at pharmacologically relevant concentrations across the indicated cell lines. Specifically, tumor cell lines originating from testicular tissues were highly sensitive to PV-10 treatment (Mean ± SD IC50: 37.5 ± 16.4 µM; n = 3) compared to breast (117.5 ± 71.0 µM; n = 3), colorectal (64.79 µM; n = 3), and head and neck (106.6 ± 29.2 µM; n = 4) cell lines. Western blot analyses showed dose- and time-dependent activation of pro-apoptotic protein markers in caspase-3 and PARP cleavage, indicating drug-induced apoptosis. Conclusions: This study provides the first pre-clinical results of PV-10 as a novel systemically-delivered therapeutic agent for a range of high-risk and refractory adult solid tumors. Data obtained from our in vitro experiments using a broad repertoire of cell lines that represent diverse molecular and phenotypic subtypes of solid tumors in adults can serve as prerequisite pre-clinical data to establish clinical testing in these populations.

Severe Cyclical Hypercortisolism Due to Metastatic Neuroendocrine Cancer Initially Diagnosed as Colon Cancer

Case Description: A 65 year-old male with initial diagnosis of metastatic colon cancer based on liver biopsy presented for evaluation of severe hypercortisolism with 24-hour urinary free cortisol (UFC) of 1184 mcg/day after presenting to his Oncologist in December 2019 requesting evaluation for muscle weakness and weight gain. On re-evaluation in March, his cortisol had dramatically improved with 24-hr UFC of 120 mcg/day and ACTH of 84 pg/mL and had resolved with 24-hr UFC of 32.6 mcg/day by May.A 2 cm pancreatic lesion was noted during cancer staging; a second opinion was obtained on the liver biopsy which was interpreted as metastatic neuroendocrine tumor, possibly of pancreatic origin. The patient was started on FOLFINIRNOX in December 2019. This was transitioned to carboplatin and etoposide after the revised diagnosis and was continued through May with regression of liver lesions on followup imaging. A 68 Ga-DOTATATE PET CT confirmed uptake in the pancreas, retroperitoneal lymph nodes, and thyroid. A thyroid ultrasound was obtained which did not meet FNA criteria.Given the chronologic association between cortisol levels and chemotherapy response we were suspicious for ectopic Cushing’s syndrome due to metastatic neuroendocrine cancer and the patient was followed for recurrence. In September, the patient endorsed leg weakness and hyperglycemia and was found to have a 24-hr UFC of 4731 mcg/day and an 8 am cortisol of 102 mcg/dL.The patient developed severe hypokalemia requiring admission and was restarted on chemotherapy with moderate improvement in cortisol levels and symptoms. Given the degree of cortisol elevation, we recommended bilateral adrenalectomy, for which the patient established care at a more specialized center.Discussion: Ectopic Cushing’s syndrome is an uncommon variety of ACTH-dependent Cushing’s syndrome caused by CRH or ACTH-producing tumors. The more aggressive form is associated with small-cell lung cancer while the chronic form is associated with indolent tumors.Cyclical Cushing’s syndrome is a rare cause of hypercortisolism characterized by cyclical variations in cortisol levels. The pathophysiology of the cyclical variation is unclear. About half of cases are caused by pituitary corticotrophs but up to 26% can be attributed to ectopic ACTH production, typically due to indolent tumors rather than aggressive malignancies.We present a case of cyclical hypercortisolism with an initial diagnosis of colon cancer. On further review, the cyclical hypercortisolism was likely associated with chemotherapy response. Reevaluation of surgical pathology was consistent with metastatic neuroendocrine cancer, the likely source of ectopic ACTH.Our case highlights the importance of maintaining a broad differential when considering cases of cyclical cortisol elevation, including consideration of concurrent chemotherapy for seemingly unrelated malignancies.

Metastatic Breast Neuroendocrine Cancer in Pregnancy: A Case of an Oncologic Emergency and a Review of Literature

Abstract Breast neuroendocrine carcinoma is a rare entity. It constitutes less than 0.5% of breast malignancies, and is usually diagnosed in older women. The occurrence of this type in young patients during pregnancy is extremely rare. Only 2 cases were previously reported. Both were diagnosed at earlier stage with the appearance of a palpable breast mass. Hereby, we present the case of a young patient at 28 weeks’ gestation admitted for severe diffuse back pain and neurologic deficit due to spinal cord compression at the level of C5 vertebra, and nerve root compression at the level of L5 vertebrae. To the best of our knowledge, this is the first case of oncologic emergency during pregnancy due to a metastatic poorly differentiated breast carcinoma with neuroendocrine differentiation in the absence of a detectable primary focus of malignancy in the breast. We also discuss the management and the obstetrical outcome of this patient.

Albumin-bilirubin grade as a prognostic indicator for patients with non-hepatocellular primary and metastatic liver malignancy undergoing Yttrium-90 radioembolization using resin microspheres.

Studies have shown that the albumin-bilirubin (ALBI) grade can be a superior prognosticator for patients undergoing Yttrium-90 (Y90) glass microsphere radioembolization for hepatocellular carcinoma (HCC) compared to the Child-Pugh (CP) scoring system. Less is known about the applicability of this score in non-hepatocellular malignancies using Y90 resin microspheres. This study evaluates the ALBI grade's ability to predict overall survival and biochemical toxicity in patients undergoing resin Y90 radioembolization and body surface area dosimetry (BSA) for non-hepatocellular primary and metastatic liver malignancies compared to the CP class and Model for End-Stage Liver Disease (MELD) score. A retrospective review of patients with intrahepatic metastatic colorectal and neuroendocrine cancers and cholangiocarcinoma undergoing resin radioembolization from 2006-2015 at a single tertiary medical center was performed. ALBI, MELD, and CP scores were compared and correlated with biochemical toxicity and overall survival. There was a significant difference in overall survival between CP class A and class B liver function (P=0.04) for the entire patient cohort. ALBI grade (P=0.36) and MELD score (P=0.19) were not independently associated with survival. When stratified by CP class, the ALBI grade revealed a trend for survival difference in CP class B (P=0.05). Baseline ALBI grade was associated with post-procedural albumin reduction (P=0.01) and bilirubin elevation (P=0.007). ALBI grade predicted post-procedural biochemical toxicity, but did not predict survival after resin radioembolization of non-hepatocellular liver malignancies using BSA dosimetry. Given the heterogeneity of this study population, dedicated prospective analyses are required.

582 The discovery of new therapeutic combinations for Merkel cell carcinoma by small-molecule synergy screening

Merkel cell carcinoma (MCC) is a rare and highly metastatic neuroendocrine skin cancer. The majority of MCC tumors are virus positive (VP-MCC) and are associated with integrated Merkel cell polyomavirus, whereas the remainder of MCC are virus-negative (VN-MCC) tumors that are characterized by ultraviolet light associated mutations. Metastatic MCC is treated by immunotherapy or chemotherapy. Conventional chemotherapy is usually unbeneficial in MCC, and although immune checkpoint inhibitor (ICI) therapy can be effective, it is contraindicated in many patients and others have disease progression despite immunotherapy.