Fusion of apoptosis-related protein Cytochrome c with anti-HER-2 single-chain antibody targets the suppression of HER-2+ breast cancer

Cancer treatment has gradually developed from toxic chemotherapy to targeted therapy with fewer side effects. Approximately 30% of breast cancer patients overexpress human epidermal growth factor receptor 2 (HER-2). Previous studies have successfully produced single-chain antibodies (scFv) targeting HER-2+ breast cancer; however, scFv have poor stability, easy aggregation and a shorter half-life, which have no significant effect on targeting therapy. Moreover, scFv has been considered as a drug delivery platform that can kill target cells by effector molecules. However, the functional killing domains of immunotoxins are mainly derived from plant or bacterial toxins, which have a large molecular weight, low tissue permeability and severe side effects. To address these concerns, we designed several apoptotic immune molecules to replace exogenous toxins using endogenous apoptosis-related protein DNA fragmentation factor 40 (DFF40) and tandem-repeat Cytochrome c base on caspase-3 responsive peptide (DEVD). Our results suggest that DFF40 or Cytc fusion scFv specifically targets HER-2 overexpressing breast cancer cells (SK-BR-3 and BT-474) rather than HER-2 negative cells (MDA-MB-231 and MCF-7). Following cellular internalization, apoptosis-related proteins inhibited tumour activity by initiating endogenous apoptosis pathways, which significantly reduced immunogenicity and toxic side effects. Therefore, we suggest that immunoapoptotic molecules may become potential drugs for targeted immunotherapy of breast cancer.

Inhibition of the Wnt/β-catenin pathway enhances antitumor immunity in ovarian cancer

Background:

The Wnt/β-catenin pathway is linked to tumorigenesis in a variety of tumors and promotes T cell exclusion and resistance to checkpoint inhibitors. We sought to determine whether a small molecule inhibitor of this pathway, WNT974, would impair tumor growth, affect gene expression patterns, and improve the immune response in human and murine ovarian cancer models.

Methods:

Human ovarian cancer cells were treated with WNT974 in vitro. RNAseq libraries were constructed and differences in gene expression patterns between responders and nonresponders were compared to The Cancer Genome Atlas (TCGA). Mice with subcutaneous or intraperitoneal ID8 ovarian cancer tumors were treated with WNT974, paclitaxel, combination, or control. Tumor growth and survival were measured. Flow cytometry and β-TCR repertoire analysis were used to determine the immune response.

Results:

Gene expression profiling revealed distinct signatures in responders and nonresponders, which strongly correlated with T cell infiltration patterns in the TCGA analysis of ovarian cancer. WNT974 inhibited tumor growth, prevented ascites formation, and prolonged survival in mouse models. WNT974 increased the ratio of CD8⁺ T cells to T regulatory cells (Tregs) in tumors and enhanced the effector functions of infiltrating CD4⁺ and CD8⁺ T cells. Treatment also decreased the expression of inhibitory receptors on CD8⁺ T cells. Combining WNT974 with paclitaxel further reduced tumor growth, prolonged survival, and expanded the T cell repertoire.

Conclusions:

These findings suggest that inhibiting the Wnt/β-catenin pathway may have a potent immunomodulatory effect in the treatment of ovarian cancer, particularly when combined with paclitaxel.

212Pb-labeled B7-H3-targeting antibody for pancreatic cancer therapy in mouse models

INTRODUCTION

We recently validated monoclonal antibody (mAb) 376.96 as an effective carrier for targeted α-particle radioimmunotherapy (RIT) with ²¹²Pb in ovarian cancer mouse models. In this study, we tested the binding of radiolabeled mAb 376.96 to human pancreatic ductal adenocarcinoma (PDAC) cells and localization in xenografts in immune-deficient mice and evaluated ²¹²Pb-labeled 376.96 (²¹²Pb-376.96) for PDAC therapy.

METHODS

In vitro Scatchard assays assessed the specific binding of ²¹²Pb-376.96 to human PDAC3 adherent differentiated cells and non-adherent cancer initiating cells (CICs) dissociated from tumorspheres. In vitro clonogenic assays were used to measure the proliferation of adherent PDAC3 cells and CIC-enriched tumorspheres treated with ²¹²Pb-376.96 or the irrelevant isotype-matched ²¹²Pb-F3-C25. Mice bearing patient derived pancreatic cancer Panc039 xenografts were i.v. injected with 0.17-0.70 MBq ²¹²Pb-376.96 or isotype control ²¹²Pb-F3-C25, and used for biodistribution and tumor growth inhibition studies. Mice bearing orthotopic PDAC3 xenografts were i.v. co-injected with ^99mTc-376.96 and ¹²⁵I-F3-C25 and used for biodistribution studies.

RESULTS

²¹²Pb-376.96 specifically bound to PDAC3 adherent and dissociated tumorsphere CICs; K_d values averaged 9.0 and 21.7 nM, respectively, with 10⁴-10⁵ binding sites/cell. ²¹²Pb-376.96 inhibited the clonogenic survival of PDAC3 cells or CICs dissociated from tumorspheres 3-6 times more effectively than isotype-matched control ²¹²Pb-F3-C25. Panc039 s.c. tumors showed significantly higher uptake of ²¹²Pb-376.96 (14.0 ± 2.1% ID/g) compared to ²¹²Pb-F3-C25 (6.5 ± 0.9% ID/g, p < .001) at 24 h after dosing. Orthotopic PDAC3 tumors showed significantly higher uptake of ^99mTc-376.96 (6.4 ± 1.8% ID/g) compared to ¹²⁵I-F3-C25 (3.9 ± 0.9% ID/g, p < .05) at 24 h after dosing. Panc039 tumor growth was significantly inhibited by ²¹²Pb-376.96 compared to ²¹²Pb-F3-C25 or non-treated control tumors (p < .05).

CONCLUSION

Our results provide evidence for the efficacy of B7-H3 targeted RIT against preclinical models of pancreatic ductal adenocarcinoma (PDAC) and support future studies with ²¹²Pb-376.96 in combination with chemotherapy to potentiate efficacy against PDAC.

Niclosamide and its analogs are potent inhibitors of Wnt/β-catenin, mTOR and STAT3 signaling in ovarian cancer

Epithelial ovarian cancer (EOC) is the leading cause of gynecologic cancer mortality worldwide. Platinum-based therapy is the standard first line treatment and while most patients initially respond, resistance to chemotherapy usually arises. Major signaling pathways frequently upregulated in chemoresistant cells and important in the maintenance of cancer stem cells (CSCs) include Wnt/β-catenin, mTOR, and STAT3. The major objective of our study was to investigate the treatment of ovarian cancer with targeted agents that inhibit these three pathways. Here we demonstrate that niclosamide, a salicylamide derivative, and two synthetically manufactured niclosamide analogs (analog 11 and 32) caused significant inhibition of proliferation of two chemoresistant ovarian cancer cell lines (A2780cp20 and SKOV3Trip2), tumorspheres isolated from the ascites of EOC patients, and cells from a chemoresistant patient-derived xenograft (PDX). This work shows that all three agents significantly decreased the expression of proteins in the Wnt/β-catenin, mTOR and STAT3 pathways and preferentially targeted cells that expressed the ovarian CSC surface protein CD133. It also illustrates the potential of drug repurposing for chemoresistant EOC and can serve as a basis for pathway-oriented in vivo studies.

Targeting the Wnt/β-catenin pathway in primary ovarian cancer with the porcupine inhibitor WNT974

Preclinical studies in ovarian cancer have demonstrated upregulation of the Wnt/β-catenin pathway promoting tumor proliferation and chemoresistance. Our objective was to evaluate the effect of the Wnt/β-catenin pathway inhibitor, WNT974, in primary ovarian cancer ascites cells. Ascites cells from patients with papillary serous ovarian cancer were isolated and treated with 1 μM WNT974±100 μM carboplatin. Viability was evaluated with the ATPlite assay. The IC50 was calculated using a dose-response analysis. Immunohistochemistry (IHC) was performed on ascites cells and tumor. Expression of R-spondin 2 (RSPO2), RSPO3, PORCN, WLS, AXIN2, and three previously characterized RSPO fusion transcripts were assessed using Taqman assays. Sixty ascites samples were analyzed for response to WNT974. The ascites samples that showed a decrease in ATP concentration after treatment demonstrated no difference from the untreated cells in percent viability with trypan blue staining. Flow cytometry demonstrated fewer cells in the G2 phase and more in the G1 and S phases after treatment with WNT974. Combination therapy with WNT974 and carboplatin resulted in a higher percentage of samples that showed ≥30% reduction in ATP concentration than either single drug treatment. IHC analysis of Wnt pathway proteins suggests cell cycle arrest rather than cytotoxicity after WNT974 treatment. QPCR indicated that RSPO fusions are not prevalent in ovarian cancer tissues or ascites. However, higher PORCN expression correlated to sensitivity to WNT974 (P=0.0073). In conclusion, WNT974 produces cytostatic effects in patient ascites cells with primary ovarian cancer through inhibition of the Wnt/β-catenin pathway. The combination of WNT974 and carboplatin induces cytotoxicity plus cell cycle arrest in a higher percentage of ascites samples than with single drug treatment. RSPO fusions do not contribute to WNT974 sensitivity; however, higher PORCN expression indicates increased WNT974 sensitivity.

Abstract POSTER-THER-1402: Overcoming platinum resistance in ovarian cancer with niclosamide

Objective: Niclosamide, a salicyclamide derivative and FDA approved teniacide, exhibits potent effects against ovarian cancer in vitro by inhibiting the Wnt/β-catenin, STAT3, and mTOR pathways. Unfortunately, its low bioavailability as a chemotherapeutic agent in vivo necessitates investigation of analogs with improved pharmacokinetics and pharmacodynamics. The objective of this study was to investigate the role of targeting the Wnt/β-catenin and STAT3 pathways with niclosamide and niclosamide analogs (C-11 and C-32) in platinum-sensitive and -resistant ovarian cancer cell lines, primary ovarian cancer ascites cell populations, and tumor tissues. In addition, carboplatin and/or LLL12, a novel STAT3 inhibitor effective against ovarian cancer, were used in combination with niclosamide and its analogs to test for synergistic cytotoxicity. Methods: Two ovarian cancer cell lines A2780, SKOV3ip1 and their chemo-resistant derivatives, A2780.cp20 and SKOV3ip2.TRip2, were treated with niclosamide or C-11 or C-32 (0.1 to 5 μM) alone or in combination with carboplatin (5 to 150 μM) or LLL12 (0.1 nM - 10 µM). Tumorspheres were isolated from the ascites of ovarian cancer patients who underwent surgery. Tumor slices were prepared from freshly obtained ovarian cancer specimens. ATPLite assay was performed to measure cytotoxicity in cell lines, tumorspheres, and tumor slices. Western blot was used to assess expression of proteins implicated in the Wnt, mTOR, and STAT3 pathways. β-catenin signaling activity was measured using the TOPflash reporter assay. Results: All four cell lines were sensitive to niclosamide, C-11, and C-32 with similar IC50 values. Additive cytotoxicity was seen when niclosamide or its analogs were combined with carboplatin or LLL12 in the cell lines, tumorspheres, and tumor tissues. Ex vivo and in vitro samples from the same patient demonstrated similar cytotoxicity with niclosamide, C-11, and C-32 treatment. Synergism was also seen between carboplatin and LLL12 in vitro. The TOPflash assay showed that the combination of niclosamide (0.4 μM) and LLL12 (0.25 μM) decreased β-catenin activity more than either agent alone, suggesting that there is crosstalk between the STAT3 and Wnt/β-catenin pathways. Wnt/β-catenin, STAT3, and mTOR pathway target proteins (LRP6, pLRP6, Axin2, and Survivin) were downregulated with niclosamide and C-32 treatment, and to a greater degree with C-11. Conclusion: Combination treatment with niclosamide, or its analogs, with carboplatin or LLL12 induced greater cytotoxicity than either agent alone in ovarian cancer cell lines, primary tumorspheres, and tumor slices. The synergistic cytotoxicity seen in platinum-resistant cell lines with niclosamide, or its analogs, in combination with carboplatin suggest that targeting the Wnt/ β-catenin and STAT3 pathways may prove effective in overcoming chemoresistance in patients with platinum resistant ovarian cancer.

Citation Format: Rebecca C. Arend, MD, Abhishek Gangrade, Christen L. Walters Haygood, MD, Chandrika Kurpad, Brandon J. Metge, Rajeev S. Samant, PhD, Pui-Kai Li, PhD, Yonghe Li, PhD, Deepak Bhasin, PhD, Charles Landen, MD, Ronald Alvarez, MD, J. Michael Straughn, MD, Donald J. Buchsbaum, PhD. Overcoming platinum resistance in ovarian cancer with niclosamide [abstract]. In: Proceedings of the 10th Biennial Ovarian Cancer Research Symposium; Sep 8-9, 2014; Seattle, WA. Philadelphia (PA): AACR; Clin Cancer Res 2015;21(16 Suppl):Abstract nr POSTER-THER-1402.

Abstract 2517: STAT3 inhibition by LLL12 in combination with niclosamide and chemotherapy in ovarian cancer

Objective:

Chemoresistance and recurrence invariably develop in the treatment of ovarian cancer, despite initial response to chemotherapy. Recent studies have shown that signal transducer and activator of transcription-3 (STAT3) signaling is associated with recurrence and development of chemoresistance in ovarian cancer. A novel small molecule, LLL12, has been shown to inhibit STAT3 in many solid tumors including colon, breast, and glioma. Niclosamide, an FDA approved salicyclamide derivative used for the treatment of tapeworm infections, has also been shown to inhibit STAT3 and other pathways including mTOR, Wnt, NfkB. Therefore, the objective of this study was to investigate LLL12 alone and in combination with niclosamide and/or chemotherapy as a potential treatment for ovarian cancer.

Methods:

Ovarian cancer cell lines A2780 and SKOV3ip2 and their carboplatin and paclitaxel chemoresistant derivatives A2780.cp20, SKOV3ip2.TR were initially treated with LLL12 alone (0.1 nM - 10 µM). These cell lines were treated with the IC50 values for LLL12 alone in combination with niclosamide (0.1 - 5 µM). Ascites was collected from a patient undergoing surgery for ovarian cancer and treated concurrently with LLL12 (0.5 - 10 μM) and carboplatin (25 - 100 μM). Cell viability was assessed using the ATP-lite assay. All samples were assayed in quadruplicate and reported as the mean ± SE.

Results:

Combination treatment with LLL12 and niclosamide produced increased cytotoxicity compared to LLL12 alone in all ovarian cancer cell lines. Treatment with chemotherapy and LLL12 showed additive cytotoxicity in the patient-derived tumorspheres. The IC50 dose of LLL12 against A2780 cells was 0.2 ± .06 but when this dose was combined with 1 µM of niclosamide, 100% cytotoxicity was achieved; 1 µM of niclosamide alone produced 80% cytotoxicity. With the A2780.cp20 cell line, LLL12 had an IC50 of 0.79 ± µM, but with 1 µM of niclosamide there was 100% cell kill, and 80% with niclosamide alone. Both SKOV3 and SKOV3ip2.TR cell lines had higher IC50 values for LLL12 (4.25 µM ± 2.1 and 2.29 µM ± 1.4, respectively) and an additive effect was achieved in both cell lines when LLL12 was combined with niclosamide. In the patient sample, a dose of 50 µM of carboplatin alone killed 10% of cells, and 10 µM of LLL12 killed 50%, The combination of 10 µM of LLL12 and 50 µM of carboplatin killed 80% of the cells; therefore an additive cytotoxicity was seen with carboplatin and LLL12.

Conclusion:

This study demonstrates that the STAT3 inhibitor, LLL12, is active against ovarian cancer cell lines and tumorspheres from a patient sample. Future animal xenograft studies will elucidate more about its activity in combination with other agents such as niclosamide and chemotherapy.

Citation Format: Rebecca C. Arend, Christen L. Walters Haygood, Chandrika Kurpad, Abhishek Gangrade, Pui-Kai Li, Yonghi Li, Deepak Bhasin, J. Michael Straughn, Donald J. Buchsbaum. STAT3 inhibition by LLL12 in combination with niclosamide and chemotherapy in ovarian cancer. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 2517. doi:10.1158/1538-7445.AM2014-2517

Abstract 4677: Niclosamide analogs for treatment of ovarian cancer

Objective: Niclosamide has shown promising activity against ovarian cancer in vitro;, however, it has low bioavailability in vivo. Thus, we investigated the cytotoxicity of niclosamide analogs in combination with carboplatin in ovarian cancer cell lines and against ovarian cancer patient ascites cells.

Methods: Tumorspheres were isolated from ascites collected from 8 patients undergoing ovarian cancer surgery at UAB. Tumorspheres were plated at 10,000 cells per 50 µL into low attachment plates. Eight patient samples were treated concurrently with niclosamide analog 11 (0.1 µM - 5 µM) and carboplatin (5 - 150 μM), while four 4 patient samples were treated with analog 32 (0.1 µM - 5 µM) and carboplatin (5 - 100 μM). After 48 hours, cells were analyzed for viability using the ATPlite assay. Analogs 11 and 32 were also assayed in combination with carboplatin against ovarian cancer cell lines, A2780, A2780.cp20, SKOV3ip2, and SKOV3ip2.TR.

Results: IC50 values for analog 11 ranged from 0.5 - 1 μM in the 8 patient ascites samples. With 150 μM carboplatin alone, patient samples had 40-80% cytotoxicity. In combination with analog 11 at 1 μM, 100% of cells were killed with 100 μM carboplatin in the 8 patient ascites samples. In the established ovarian cancer cell lines, cytotoxicity approached 100% at a dose of 3 - 5 μM of analog 11. In the 4 patient samples treated with analog 32, IC50 values ranged from 0.4 μM - 3 μM. With 100 μM carboplatin alone, patient samples had 40-80% cytotoxicity. In combination with 100 μM carboplatin, nearly 100% of cells were killed at a dose of 1 μM of analog 32. In the cell lines, IC50 values for analog 32 ranged from 0.9 - 2.5 μM. With combination treatment, there was increased cytotoxicity in the chemoresistant cells, A2780.cp20 and SKOV3ip2, compared to carboplatin alone.

Conclusion: These niclosamide analogs produced cytotoxicity both alone and in combination with carboplatin against ovarian cancer cells and tumorspheres from patient ascites. Future studies will evaluate the PK/PD of the analogs.

Citation Format: Christen L. Walters Haygood, Rebecca C. Arend, Pui-Kai Li, Yonghe Li, Chandrika Kurpad, Abhishek Gangrade, John M. Straughn, Donald Buchsbaum. Niclosamide analogs for treatment of ovarian cancer. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 4677. doi:10.1158/1538-7445.AM2014-4677

The Effect of Phosphatidylserine on T Cell and Dendritic Cell Function (90.2)

Phosphatidylserine (PS) is a phospholipid of plasma membrane. PS is located in the inner leaflet of plasma membrane but turns to outer leaflet when cell death program is initiated. It has been demonstrated that PS on apoptotic cells plays an important role in modulating immune responses. However, whether apoptotic cells release soluble PS which may subsequently affect immunocytes is not known. Recently, we found that apoptotic cells released soluble PS to the culture media which could block the binding of anti-PS antibody to apoptotic cells. To address how soluble PS influences T cell and dendritic cell function, we examined the effect of water-soluble PS (Avanti Polar Lipids, &gt;95% purity with no endotoxin) on T cell proliferation, and monocyte-derived dendritic cell (DC) cytokine and chemokine production. Our results demonstrated that PS suppressed T cell proliferation in a significant dose-dependent manner. However, PS appeared not affecting T cell early activation based on the normal up-regulation of CD69. On DCs, PS did not induce any cytokine or chemokine production. However, PS significantly altered LPS-stimulated DC cytokine and chemokine producing profiles. We found that PS enhanced LPS-induced IL-1beta, IL-alpha, GM-CSF and IL-6, but suppressed IL-10, IL-12p40 as well as most chemokines tested. There was no significant influence on DC maturation. Our findings indicate that the apoptotic cells may modulate immune responses through releasing soluble PS. The mechanisms of PS effect on T cells and DCs are being investigated.