The synergistic effect of chemo-photothermal therapies in SN-38-loaded gold-nanoshell-based colorectal cancer treatment

Aim: 7-Ethyl-10-hydroxycamptothecin (SN-38)-loaded gold nanoshells nanoparticles (HSP@Au NPs) were developed for combined chemo-photothermal therapy to treat colorectal cancer. Materials & methods: SN-38-loaded nanoparticles (HSP NPs) were prepared by the lyophilization-hydration method, and then developed into gold nanoshells. The nanoparticles were characterized and assessed for photothermal properties, cytotoxicity and hemocompatibility in vitro. In vivo anticancer activity was tested in a tumor mouse model. Results: The HSP@Au NPs (diameter 186.9 nm, zeta potential 33.4 mV) led to significant cytotoxicity in cancer cells exposed to a near-infrared laser. Moreover, the HSP@Au NP-mediated chemo-photothermal therapy displayed significant tumor growth suppression and disappearance (25% of tumor clearance rate) without adverse side effects in vivo. Conclusion: HSP@Au NPs may be promising in the treatment of colorectal cancer in the future.

KSHV transactivator-derived small peptide traps coactivators to attenuate MYC and inhibits leukemia and lymphoma cell growth

In herpesvirus replicating cells, host cell gene transcription is frequently down-regulated because important transcriptional apparatuses are appropriated by viral transcription factors. Here, we show a small peptide derived from the Kaposi’s sarcoma-associated herpesvirus transactivator (K-Rta) sequence, which attenuates cellular MYC expression, reduces cell proliferation, and selectively kills cancer cell lines in both tissue culture and a xenograft tumor mouse model. Mechanistically, the peptide functions as a decoy to block the recruitment of coactivator complexes consisting of Nuclear receptor coactivator 2 (NCOA2), p300, and SWI/SNF proteins to the MYC promoter in primary effusion lymphoma cells. Thiol(SH)-linked alkylation for the metabolic sequencing of RNA (SLAM seq) with target-transcriptional analyses further confirm that the viral peptide directly attenuates MYC and MYC-target gene expression. This study thus provides a unique tool to control MYC activation, which may be used as a therapeutic payload to treat MYC-dependent diseases such as cancers and autoimmune diseases.

Inhibiting IL-6/STAT3/HIF-1α signaling pathway suppressed the growth of infantile hemangioma

Purpose This study aimed to evaluate the expression of Interleukin 6 (IL-6) in IH patients and investigate the role of IL-6/signal transducers and activators of transduction-3 (STAT3)/hypoxia inducible factor-1α (HIF-1α) pathway in the progression of infantile hemangioma (IH). Methods Serum samples obtained from IH patients and normal infants were measured for IL-6 expression. Hemangioma-derived stem cells (HemSCs) were transfected with siRNAs targeting IL-6, HIF-1α or STAT3. And then, cell-viability assay and wound healing assay were conducted. After that, the tumor mouse model of HemSCs was established. The in vivo anticancer effect of IL-6 inhibitor was investigated. Results IH patients had much higher IL-6 levels as comparing to the healthy controls (P=0.005). HemSCs transfected with IL-6 siRNA had significantly lower viability and migration rate than normal HemSCs. And HemSCs transfected with STAT3 siRNA or HIF-1α siRNA had the similar tendency. On tumor bearing mice, IL-6 inhibitor treatment significantly delayed the tumor growth. Compared with control group, Caspase 3 was significantly increased in IL-6 inhibitor group (P<0.05), whereas Ki67 was decreased in IL-6 inhibitor group (P<0.05). In TUNEL assay, IL-6 inhibitor group had much higher apoptosis rate than control (P<0.05). Conclusion Our findings indicated that inhibiting IL-6/STAT3/HIF-1α signaling pathway could suppress IH growth.

KSHV transactivator-derived small peptide traps coactivators to attenuate MYC function and kills leukemia and lymphoma

In herpesvirus replicating cells, host cell gene transcription is frequently down-regulated because important transcriptional apparatuses are appropriated by viral transcription factors. Here, we identified a small peptide derived from the Kaposi's sarcoma-associated herpesvirus transactivator (K-Rta) sequence, which attenuates cellular c-MYC expression, reduces cell proliferation, and selectively kills cancer cell lines in both tissue culture and a xenograft tumor mouse model. Mechanistically, the peptide functions as a decoy to block the recruitment of coactivator complexes consisting of Nuclear receptor coactivator 2 (NCOA2), p300, and SWI/SNF proteins to the MYC promoter in primary effusion lymphoma cells. Thiol(SH)-linked alkylation for the metabolic sequencing of RNA (​SLAM seq) with target-transcriptional analyses further confirmed that the viral peptide directly attenuates MYC and MYC-target gene expression. This study thus provides a unique tool to control MYC activation, which may have significant potential as a therapeutic payload to treat MYC-dependent diseases such as cancers and autoimmune diseases.

Targeting Tumor Cells with Nanoparticles for Enhanced Co-Drug Delivery in Cancer Treatment

Gastric cancer (GC) is a fatal malignant tumor, and effective therapies to attenuate its progression are lacking. Nanoparticle (NP)-based solutions may enable the design of novel treatments to eliminate GC. Refined, receptor-targetable NPs can selectively target cancer cells and improve the cellular uptake of drugs. To overcome the current limitations and enhance the therapeutic effects, epigallocatechin-3-gallate (EGCG) and low-concentration doxorubicin (DX) were encapsulated in fucoidan and d-alpha-tocopherylpoly (ethylene glycol) succinate-conjugated hyaluronic acid-based NPs for targeting P-selectin-and cluster of differentiation (CD)44-expressing gastric tumors. The EGCG/DX-loaded NPs bound to GC cells and released bioactive combination drugs, demonstrating better anti-cancer effects than the EGCG/DX combination solution. In vivo assays in an orthotopic gastric tumor mouse model showed that the EGCG/DX-loaded NPs significantly increased the activity of gastric tumors without inducing organ injury. Overall, our EGCG/DX-NP system exerted a beneficial effect on GC treatment and may facilitate the development of nanomedicine-based combination chemotherapy against GC in the future.

Both T cell priming in lymph node and CXCR3-dependent migration are the key events for predicting the response of atezolizumab

Anti-PD-L1 antibodies benefit many cancer patients, even those with “non-inflamed tumor”. Determining which patients will benefit remains an important clinical goal. In a non-inflamed tumor mouse model, we found that PD-L1 was highly expressed on antigen-presenting cells (APCs) especially on CD103+ CD11c+ dendritic cells in tumor-draining lymph nodes (dLNs), suppressing T-cell priming by APCs. In this model, anti-PD-L1 antibodies enhanced T-cell priming and increased CXCR3+ activated T-cells in dLNs, which was followed by the trafficking of T-cells to tumors in response to CXCR3 ligands. As predictive biomarker, each APCs-related gene expression (AP score) alone or T-cells trafficking-related chemokine gene expression (T score) alone were still less than perfect among the 17 mouse models examined. However a combining score of AP score and T score (AP/T score) precisely identified anti-PD-L1-sensitive tumors. In the phase 3 trial of atezolizumab vs docetaxel in advanced NSCLC patients (OAK), the AP/T score could identify atezolizumab-treated NSCLC patients who achieved significant improvement in overall survival. This biomarker concept would be a clinically valuable for prediction of anti-PD-L1 antibody efficacy.

HGG-30. BRAIN PENETRANT HDAC INHIBITOR RG2833 SYNERGIZES WITH LOMUSTINE AND RADIATION TO INDUCE DIPG CELL DEATH

Diffuse intrinsic pontine glioma (DIPG) is driven by epigenetic dysregulation. The pan-HDAC inhibitor panobinostat showed pre-clinical efficacy against DIPG, but was limited by toxicity in clinical trials. RG2833 (RGFP109) is a selective HDAC1/3 inhibitor with established brain penetration. RG2833 reverses temozolomide-resistance in glioblastoma through downregulation of the NFĸB pathway. As this pathway is upregulated in DIPG and may contribute to tumorigenesis, we hypothesized that RG2833 would kill DIPG cells. We found that RG2833 treatment inhibits cell growth in the 4 to 9μM range in both autopsy and biopsy-derived DIPG cell lines (MTS assay for HSJD007 p=0.0004, JHH-DIPG1 p=0.001, SF-7761 p=0.04, SU-DIPG13 p=0.01 by t-test). Western blot confirmed on target activity by increased histone 3 acetylation at IC50 doses. RG2833 induces apoptosis (cPARP Western blot, cleaved caspase 3 immunofluorescence HSJD007 p&lt;0.003, JHH-DIPG1 p=0.0026 by t-test) and slows cell proliferation (phospho-Rb Western blot, BrdU immunofluorescence HSJD007 p=0.008, JHH-DIPG1 p=0.0002 by t-test) in multiple DIPG cell lines. RG2833 disrupts the NFĸB pathway through acetylation of p65, resulting in decreased expression of NFĸB regulated pro-survival genes (Western blot for BCL2, BCL-xL, and XIAP). In a DIPG flank tumor mouse model, treatment with RG2833 alone for 1 week suppresses flank tumor growth (p&lt; 0.005 by t-test) and induces apoptosis (Western blot for cPARP). We next assessed whether RG2833 combines synergistically with conventional therapies. We found that RG2833 has strong synergism with both lomustine and radiation to slow DIPG cell growth in vitro (ZIP synergy scores by SynergyFinder for RG2833+lomustine in JHH-DIPG1 17.8 and HSJD007 17.7, RG2833+radiation in JHH-DIPG1 9.7 and JHH-DIPG16A 10.9). Evaluation of combination treatment for apoptotic effects in vitro and in vivo are ongoing. This data identifies selective HDAC inhibitor RG2833 as a promising therapy for DIPG that combines synergistically with conventional therapies.

Tissue distribution and brain penetration of niraparib in tumor bearing mouse models and its clinical relevance.

e15066 Background: Cancer therapies that effectively cross the blood-brain barrier (BBB) to treat primary and metastatic brain tumors represent a critical unmet medical need. Brain metastasis are diagnosed in 10-40% of solid tumors and are associated with poor outcomes1. Preclinical data showed that niraparib has shown higher brain penetration as compared to other PARP inhibitors in an intact BBB setting2,3; however limited data is available to understand the penetration and residence of PARP inhibitors in a disrupted BBB setting. We conducted studies to assess the brain penetration of niraparib and olaparib in a disrupted BBB setting in an orthotopic animal tumor model. Additionally, we report tissue biodistribution of niraparib in a xenograft tumor mouse model. Methods: Brain penetration of niraparib and olaparib was assessed in GL261 orthotopic glioblastoma models. Niraparib and olaparib were dosed at 35 and 50 mg/kg once daily for 3-days, respectively. Brain tumor and contralateral normal brain region were excised following 3-day dosing. In a separate study niraparib tissue distribution in various organs was monitored in an ovarian (A2780) xenograft tumor mouse model. Several organs including tumors were excised following 5-day oral dosing of niraparib at 35mg/kg. Tissue samples were processed by homogenization followed by analysis using LC-MS/MS. Data were analyzed using non-compartmental analysis. Results: Mean drug concentrations at 2h post last dose in brain tumor region and normal contralateral brain region were 24µM and 2.15µM for niraparib compared with 0.7µM and 0.18µM for olaparib. Mean drug concentration at 24h post last dose in brain tumor region and normal contralateral region were 1.36µM and 0.53µM for niraparib compared with 0.17µM and 0.01µM for olaparib. In a A2780 xenograft tumor model tissue distribution study, niraparib demonstrated high levels of tissue penetration and retention in most perfused (lung, liver, kidney) and non-perfused tissues (tumor, ovary, pancreas). In most cases, tissues had at least 2-fold higher exposure than plasma at steady state following repeat oral dosing. Conclusions: Niraparib brain tumor tissue concentration was at least 25-fold greater than olaparib at 2h post dose. Data also suggests niraparib had better retention in brain tumor over olaparib with mean exposure as high as 1.4µM at 24h post dose (terminal phase) with just 3-days of dosing. These findings demonstrated that a favorable pharmacokinetic profile of niraparib was achieved in the disrupted BBB setting of the glioblastoma model. High penetration of niraparib in brain and other tissues along with a strong correlation with systemic exposures support the future investigation of niraparib in cancers with high incidence of brain metastasis. References: 1. Epidemiology, Biology, and Therapy; Chapter 1; 2015, Pages 3-29. 2. Oncotarget . 2018 Dec 14; 9(98): 37080–37096. 3. AACR 2019, Poster 3888.