A natural product, Piperlongumine (PL), increases tumor cells sensitivity to NK cell killing.

Natural Killer (NK) cells are components of innate immune surveillance against transformed cells. NK cell immunotherapy has attracted attention as a promising strategy for cancer treatment, whose antitumor effects, however, require further improvement. The use of small molecules with immunomodulatory potentials and selective tumor-killing possesses the potential to complement immunotherapy. This study demonstrated that Piperlongumine (PL), a natural alkaloid obtained from long pepper fruit, alone has antitumor and anti-proliferative potential on all the tested tumors in vitro. PL pretreatment of tumor cells also potentiates their susceptibility to NK cell cytolysis at the doses where NK cell functions were preserved. Importantly, PL suppresses both NK -sensitive MHC-I -deficient and MHC-I -sufficient tumor growth in vivo. Mechanistically, PL induces misfolded proteins, impedes autophagy, increases ROS and tumor conjugation with NK cells. Furthermore, PL enhances the expression of NK cell-activating receptors on NK cells and its ligands on tumor cells, possibly leading to increased susceptibility to NK cell killing. Our findings showed the antitumor and immunomodulatory potential of PL, which could be explored to complement NK cell immunotherapy for cancer treatment.

Novel Chinese Angelica Polysaccharide Biomimetic Nanomedicine to Curcumin Delivery for Hepatocellular Carcinoma Treatment and Immunomodulatory Effect.

BACKGROUND: Using natural polysaccharides from Traditional Chinese Medicine as nanodrug delivery systems have considerable potential for tumor diagnostics and therapeutics. PURPOSE: On the basis of targeted therapy and combining the advantages of natural polysaccharides (angelica polysaccharide, APS) and natural Chinese medicine (curcumin, Cur) to design functionalized nanoparticles to improve the therapeutic through cell membrane encapsulation and immunotherapy. STUDY DESIGN AND METHODS: Cur-loaded, glycyrrhetic acid (GA)-APS-disulfide bond (DTA)-Cur nanomicelle (GACS-Cur), which were prepared by the dialysis method. GACS-Cur was encapsulated with the membranes from red blood cells (RBCm) termed GACS-Cur@RBCm, which were prepared by the principle of extrusion using a miniature extruder. The developed formulations were subjected to various in vitro and in vivo evaluation tests. RESULTS: The resulting APS nanocarriers supported a favorable drug-loading capacity, biocompatibility, and enhanced synergistic anti-hepatoma effects both in vitro and in vivo. After administration in mice, in vivo imaging results showed that the GACS-Cur and RBCm-coated groups had an obvious stronger tumor tissue targeting ability than the control treatment groups. Additionally, the immunomodulatory effect increased IL-12, TNF-α and IFN-γ expression and CD8+ T cell infiltration (1.9-fold) than that of the saline group. Notably, in comparison with hyaluronic acid (HA) nanocarriers, APS nanocarriers possess higher anti-hepatoma efficiency and targeting capabilities and, thus, should be further studied for a wide range of anti-cancer applications. CONCLUSION: Our data demonstrated that APS nanocarriers encapsulated with erythrocyte membrane mighty be a promising clinical method in the development of efficacy, safety and targeting of liver cancer therapy.

Six-step etoposide desensitization protocol: A pediatric, adolescent, and young adult case series.

Etoposide administration can be complicated by hypersensitivity reactions. Desensitization may provide a strategy to prevent hypersensitivity recurrence. One challenge with desensitization is regimen complexity. This case series describes 12 pediatric, adolescent, and young adult patients who received a simplified six-step etoposide desensitization protocol. This protocol contains 50% fewer titration steps compared with previously described protocols and eliminates infusion rate changes during titration. Simplified titration may minimize risk of error during administration and improve safety. This protocol was tolerated by 92% of patients. Given increasing frequency and duration of drug shortages, a simplified desensitization protocol provides a valuable treatment option.

Immunomodulation of Chinese Herbal Medicines on NK cell populations for cancer therapy: A systematic review.

ETHNOPHARMACOLOGICAL RELEVANCE: Immunomodulation has become a crucial modality for cancer treatment. Chinese Herbal Medicines (CHMs) are expected as adjuvant therapy for immunomodulation against cancer, but face the key challenge of poor scientific evidence. Changes of natural killer (NK) cells on numbers and/or cytotoxicity are a novel respect to evaluate the immunomodulation of CHMs. AIM OF THE STUDY: The purpose of this review is to investigate the immunomodulation of Chinese Herbal Medicines (CHMs) on NK cell populations for cancer therapy. MATERIALS AND METHODS: A systematic review was conducted and outside mainstream electronic databases were screened for potential reference articles. This review tried to report and critically analyzed all the correlative studies, especially these clinical trials (3 CHM extracts and 11 CHM formulas). RESULTS: Evidence-based functions of CHMs against cancer could be summarized as: (1) enhancement of NK cells activity or relative percentage; (2) prevention of tumor growth and metastasis; (3) relief on side-effects or complications of therapeutic strategies (i.e. chemotherapy, radiotherapy and resection). Briefly, most of cellular studies and two thirds animal studies were based on the extract or components of single herbs, whilst most of clinical trials were keen on formula or prescription of CHMs. The main components of CHMs were demonstrated active on promoting the cytotoxicity of NK cells, including Angelica sinensis, Ganoderma lucidum, Panax ginseng, Radix Astragali, Lentinus edodes, etc. CONCLUSIONS: This comprehensive review demonstrated NK cells activity was positively associated with quality of life but not survival benefit of cancer patients. Thus exploring the roles of NK cells in adjuvant therapy against cancer is confirmed to be beneficial to explore the underlying relationship between immunomodulation and quality of life.

Tumour sensitization via the extended intratumoural release of a STING agonist and camptothecin from a self-assembled hydrogel.

Tumours with an immunosuppressive microenvironment respond poorly to therapy. Activation of the stimulator of interferon genes (STING) pathway can enhance intratumoural immune activation, but STING agonists are associated with high toxicity and degrade prematurely, which limits their effectiveness. Here, we show that the extended intratumoural release of the STING agonist cyclic di-AMP transforms the tumour microenvironment from immunosuppressive to immunostimulatory, increasing the efficacy of antitumour therapies. The STING agonist was electrostatically complexed with nanotubes comprising a peptide-drug conjugate (a peptide that binds to the protein neuropilin-1, which is highly expressed in tumours, and the chemotherapeutic agent camptothecin) that self-assemble in situ into a supramolecular hydrogel. In multiple mouse models of murine tumours, a single low dose of the STING agonist led to tumour regression and increased animal survival, and to long-term immunological memory and systemic immune surveillance, which protected the mice against tumour recurrence and the formation of metastases. Locally delivered STING agonists could help to reduce tumour immunosuppression and enhance the efficacy of a wide range of cancer therapies.

The extracts of Astragalus membranaceus overcome tumor immune tolerance by inhibition of tumor programmed cell death protein ligand-1 expression.

A polysaccharide isolated from the radix of Astragalus membranaceus, called PG2, used in traditional Chinese medicine, with potential hematopoiesis inducing and immunomodulation activities. PG2 extracted from A. membranaceus has been demonstrated as a novel alternative medicine for cancer patients. Recently, we demonstrated that PG2 enhanced chemotherapy through bystander effect and reduced the expression of indoleamine 2, 3-dioxygenase 1 in tumor cells. Many tumors have been proven to have a high expression of programmed cell death protein ligand-1 (PD-L1), which binds with programmed cell death protein-1(PD-1) in immune cells, thus causing immune tolerance within the tumor microenvironment. With decreased expression of PD-L1, increased immune response can be observed, which might be helpful when developing tumor immunotherapy. The antitumor therapeutic effect mediated by PG2 may associate with an inflammatory immune response at the tumor site. However, the molecular mechanism that by which PG2 inhibits PD-L1 is still incompletely known. The expression of PD-L1 was decreased after tumor cells were treated with PG2. In addition, the cell signaling pathway in tumor cells was evaluated by Western blotting analysis after PG2 treatment. PG2 can downregulate the expression of PD-L1 on the cell surface via the protein kinase B (Akt)/mammalian target of rapamycin (mTOR)/ribosomal protein S6 kinase beta-1 (p70S6K) pathway. In conclusion, our results indicate that PG2 inhibits PD-L1 expression and plays a crucial role in immunotherapy, which might be a promising strategy combined with other treatments.

Improvement of heavy and light chain assembly by modification of heavy chain constant region 1 (CH1): Application for the construction of an anti-paclitaxel fragment antigen-binding (Fab) antibody.

Formation of disulfide bonds between heavy and light chains is challenge for production of recombinant immunoglobulin G (IgG) and fragment antigen-binding (Fab). Insufficient formation of the bond influences productive yield and quality of recombinant IgG and Fab. To investigate how amino acid sequences of the first heavy chain constant region (CH1) effect on assembly between heavy chain (VH-CH1 or Fd) and light chain (VL-CL), the CH1 gene sequence of an anti-paclitaxel fragment antigen-binding (anti-PT Fab IgG2a) was modified using the splicing by overlap extension-polymerase chain reaction (SOE-PCR) to be gene sequences encoding amino acid sequence of IgG1, IgG2b, and IgG3 subtypes. These anti-PT Fabs were expressed in Escherichia coli and silkworm larva expression systems. The efficiency of the assembly between VH-CH1 and VL-CL was evaluated. Based on sodium dodecyl sulfate polyacrylamide gel electrophoresis and Western blot analysis, assembly between heavy of IgG1 subtype and light chain was found to be superior over other subtypes using all tested expression systems. Furthermore, reactivity analysis using an enzyme-linked immunosorbent assay (ELISA) revealed that anti-PT Fab IgG1 subtype showed the highest reactivity against target compound paclitaxel. The folding efficiency and reactivity of the anti-PT Fab was influenced by CH1 amino acid sequence, which raises the possibility that this modification can be applied to improve recombinant Fab production.

Development of a Competitive Time-Resolved Fluoroimmunoassay for Paclitaxel.

INTRODUCTION: Paclitaxel (Tax) is a diterpene alkaloid isolated from Taxus species and has proved clinically effective in treating a number of malignancies. Current quantitative analytical methods for Tax such as high-performance liquid chromatography (HPLC) often involve complicated sample preparation procedures with low recovery rates. OBJECTIVE: To establish a rapid and sensitive time-resolved fluoroimmunoassay (TRFIA) for measuring Tax in Taxus materials with convenient sample preparation and a high recovery rate. METHODS: Rabbit anti-mouse IgG was coated onto a 96-well microplate, which was then incubated with standard solutions of Tax and anti-Tax monoclonal antibody 3A3. A Eu3+ -labelled conjugate of Tax and human serum albumin was used as the tracer. The luminescent system was enhanced with a solution containing 2-naphthoyltrifluoroacetone. RESULTS: The established TRFIA showed a linear response within the Tax concentration range of 3.2 to 80 ng/mL, with a limit of detection of 1.4 ng/mL. The intra- and inter-assay coefficient of variation of the assay was 9.6% and 9.7%, respectively, with an average recovery rate from spiked samples of 108.5%. Tax contents in Taxus samples were determined using both the established TRFIA system and a previously established enzyme-linked immunosorbent (ELISA), and the results of two assays were well correlated. CONCLUSION: This TRFIA system shows a high sensitivity, precision and accuracy for detection of Tax. This assay, which is convenient and less time-consuming, allows rapid analysis of Tax and provides another option for Tax measurement for quality control of Taxus materials and products. Copyright © 2017 John Wiley & Sons, Ltd.

Development of an indirect competitive enzyme-linked immunosorbent assay (icELISA) using highly specific monoclonal antibody against paclitaxel.

Paclitaxel, the major active component of the yew tree, is used as an important anti-cancer agent. To obtain the monoclonal antibody (MAb) against paclitaxel for paclitaxel determination using immunoassay, 7-xylosyltaxol was conjugated to the carrier protein bovine serum albumin (BSA) to construct the immunogen, and the ratio of hapten in XylTax-BSA conjugate was determined by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. After immunization of mice with this conjugate, hybridomas secreting MAbs against paclitaxel were obtained by fusing the splenocytes with the mouse myeloma cell line SP2/0. After hybridoma screening, the anti-paclitaxel MAb 3A3 was obtained, which showed a relatively high specificity to paclitaxel (cross-reactivities against other naturally occurred taxanes: 7-xylosyltaxol, 31.8%; cephalomannine, 6.17%; baccatin III, 10-deacetyl-baccatin III, 1-hydroxybaccatin I, 13-acetyl-9-dihydrobaccatin III and 1-acetoxyl-5-deacetyl-baccatin I, <0.11%). Using the MAb 3A3, we established an indirect competitive enzyme-linked immunosorbent assay (icELISA) for paclitaxel determination with a detection range of 0.098-312.5 µg ml(-1). Determination of paclitaxel contents in various yew tree samples with this icELISA resulted in recovery rates ranging from 92 to 94.8%, and intra- and inter-assay variations of 3.6 and 4.7%, respectively. This icELISA provides a valuable method of paclitaxel determination for various purposes.

Cell-targeting fusion constructs containing recombinant gelonin.

Therapeutic agents capable of targeting tumor cells present as established tumors and micrometastases have already demonstrated their potential in clinical trials. Immunotoxins targeting hematological malignancies and solid tumors have additionally demonstrated excellent clinical activity. This review focuses on our design and characterization studies of constructs composed of recombinant gelonin toxin fused to either growth factors or single-chain antibodies targeting solid tumor cells, tumor vasculature or hematological malignancies. These agents demonstrate cytotoxicity at nanomolar or sub-nanomolar levels. All of these constructs display impressive selectivity and specificity for antigen-bearing target cells in vitro and in vivo and are excellent clinical trial candidates.

Safety of higher dosages of Viscum album L. in animals and humans--systematic review of immune changes and safety parameters.

BACKGROUND: Viscum album L extracts (VAE, mistletoe) and isolated mistletoe lectins (ML) have immunostimulating properties and a strong dose-dependent cytotoxic activity. They are frequently used in complementary cancer treatment, mainly to improve quality of life, but partly also to influence tumour growth, especially by injecting VAE locally and in high dosage. The question is raised whether these higher dosages can induce any harm or immunosuppressive effects. METHODS: Systematic review of all experiments and clinical studies investigating higher dosages of VAE in animals and humans (Viscum album > 1 mg in humans corresponding to > 0.02 mg/kg in animals or ML > 1 ng/kg) and assessing immune parameters or infections or adverse drug reactions. RESULTS: 69 clinical studies and 48 animal experiments reported application of higher doses of VAE or ML and had assessed immune changes and/or harm. In these studies, Viscum album was applied in dosages up to 1500 mg in humans and 1400 mg/kg in animals, ML was applied up to 6.4 µg/kg in humans and in animals up to 14 µg/kg subcutaneously, 50 µg/kg nasally and 500 µg/kg orally. A variety of immune parameters showed fluctuating or rising outcomes, but no immunosuppressive effect. Side effects consisted mainly of dose-dependent flu-like symptoms (FLS), fever, local reactions at the injection site and various mild unspecific effects. Occasionally, allergic reactions were reported. After application of high doses of recombinant ML, reversible hepatotoxicity was observed in some cases. CONCLUSIONS: Application of higher dosages of VAE or ML is not accompanied by immunosuppression; altogether VAE seems to exhibit low risk but should be monitored by clinicians when applied in high dosages.

Development of an enzyme-linked immunosorbent assay system to determine the presence of antibodies specific for taxane structures.

Taxanes, which are widely used in treatment of numerous cancer types, are well-known to induce hypersensitivity reactions (HSR), especially in the case of paclitaxel. Although the cause of the HSR is commonly thought to be a non-immunological direct effect of the diluent which is used to dissolve paclitaxel, some reports suggest the possibility of the presence of an immunological reaction to the common taxane structure. The aim of this study was to establish a method to determine the presence of anti-taxane antibodies in body fluids of patients who have previously received paclitaxel, in order to estimate the risk of the occurrence of HSR to other taxane compounds, such as docetaxel. To prepare an enzyme-linked immunosorbent assay (ELISA) plate for determining taxanes, 10-deacetylbaccatin III (DAB) was first succinylated by use of dimethylaminopyridine and succinic anhydride in dried pyridine. After the succinylation reaction, three different products were obtained, and these were confirmed as 7-succinoyl DAB (7-DAB), 10-succinoyl DAB (10-DAB), and 7,10-disuccinoyl DAB (7,10-DAB) by (1)H-NMR analysis. Each of these three products was conjugated with bovine serum albumin (BSA), and adsorbed on an ELISA plate. By using a commercially available anti-taxane monoclonal antibody as a model antibody, the detection limit of the anti-taxane antibodies on the 7-DAB-BSA-, 10-DAB-BSA-, and 7,10-DAB-BSA-conjugated ELISA plate was estimated as 0.3, 1 and 10 ng/ml, respectively. The ELISA system established in this study may therefore be useful for estimating the risk of HSR to taxanes in a patient prior to the use of these drugs.

Selective formation of covalent protein heterodimers with an unnatural amino acid.

We report a strategy for the generation of heterodimeric protein conjugates using an unnatural amino acid with orthogonal reactivity. This paper addresses the challenges of site-specificity and homogeneity with respect to the synthesis of bivalent proteins and antibody-drug conjugates. There are numerous antibody-drug conjugates in preclinical and clinical development, yet these are based either on nonspecific lysine coupling chemistry or on disulfide modification made difficult by the large number of cysteines in antibodies. Here, we describe a recombinant approach that can be used to rapidly generate a variety of constructs with defined conjugation sites. Moreover, this methodology results in homogeneous antibody conjugates whose biological, physical, and pharmacological properties can be quantitatively assessed and subsequently optimized. As proof of concept, we have generated anti-Her2 Fab-Saporin conjugates that demonstrate excellent potency in vitro.

Maytansine and cellular metabolites of antibody-maytansinoid conjugates strongly suppress microtubule dynamics by binding to microtubules.

Maytansine is a potent microtubule-targeted compound that induces mitotic arrest and kills tumor cells at subnanomolar concentrations. However, its side effects and lack of tumor specificity have prevented successful clinical use. Recently, antibody-conjugated maytansine derivatives have been developed to overcome these drawbacks. Several conjugates show promising early clinical results. We evaluated the effects on microtubule polymerization and dynamic instability of maytansine and two cellular metabolites (S-methyl-DM1 and S-methyl-DM4) of antibody-maytansinoid conjugates that are potent in cells at picomolar levels and that are active in tumor-bearing mice. Although S-methyl-DM1 and S-methyl-DM4 inhibited polymerization more weakly than maytansine, at 100 nmol/L they suppressed dynamic instability more strongly than maytansine (by 84% and 73%, respectively, compared with 45% for maytansine). However, unlike maytansine, S-methyl-DM1 and S-methyl-DM4 induced tubulin aggregates detectable by electron microscopy at concentrations ≥2 µmol/L, with S-methyl-DM4 showing more extensive aggregate formation than S-methyl-DM1. Both maytansine and S-methyl-DM1 bound to tubulin with similar K(D) values (0.86 ± 0.2 and 0.93 ± 0.2 µmol/L, respectively). Tritiated S-methyl-DM1 bound to 37 high-affinity sites per microtubule (K(D), 0.1 ± 0.05 µmol/L). Thus, S-methyl-DM1 binds to high-affinity sites on microtubules 20-fold more strongly than vinblastine. The high-affinity binding is likely at microtubule ends and is responsible for suppression of microtubule dynamic instability. Also, at higher concentrations, S-methyl-DM1 showed low-affinity binding either to a larger number of sites on microtubules or to sedimentable tubulin aggregates. Overall, the maytansine derivatives that result from cellular metabolism of the antibody conjugates are themselves potent microtubule poisons, interacting with microtubules as effectively as or more effectively than the parent molecule.

Maytansinoid-antibody conjugates induce mitotic arrest by suppressing microtubule dynamic instability.

Maytansine and its analogues (maytansinoids) are potent microtubule-targeted compounds that inhibit proliferation of cells at mitosis. Antibody-maytansinoid conjugates consisting of maytansinoids (DM1 and DM4) attached to tumor-specific antibodies have shown promising clinical results. To determine the mechanism by which the antibody-DM1 conjugates inhibit cell proliferation, we examined the effects of the cleavable anti-EpCAM-SPP-DM1 and uncleavable anti-EpCAM-SMCC-DM1 conjugates on MCF7 human breast tumor cells. We also examined the effects of the free maytansinoids, maytansine and S-methyl DM1 (a version of DM1 that is stable in cell culture medium), for comparison. Both the conjugates and free maytansinoids potently inhibited MCF7 cell proliferation at nanomolar and subnanomolar concentrations, respectively, by arresting the cells in mitotic prometaphase/metaphase. Arrest occurred in concert with the internalization and intracellular processing of both conjugates under conditions that induced abnormal spindle organization and suppressed microtubule dynamic instability. Microtubule depolymerization occurred only at significantly higher drug concentrations. The results indicate that free maytansinoids, antibody-maytansinoid conjugates, and their metabolites exert their potent antimitotic effects through a common mechanism involving suppression of microtubule dynamic instability.

Engineering and biological characterization of VB6-845, an anti-EpCAM immunotoxin containing a T-cell epitope-depleted variant of the plant toxin bouganin.

The clinical development of immunotoxins in the treatment of solid tumors has been impeded in part, by the induction of an immune response directed primarily against the toxin moiety. Bouganin, a type I ribosome inactivating protein isolated from the leaf of Bougainvillea spectabilis Willd, was mutated to remove the T-cell epitopes while preserving the biological activity of the wild-type molecule. The T-cell epitope-depleted variant of bouganin (de-bouganin) was genetically linked to an anti-epithelial cell adhesion molecule (EpCAM) Fab moiety via a peptidic linker containing a furin proteolytic site to create the fusion construct VB6-845. To determine the optimal construct design for VB6-845, several dicistronic units where de-bouganin was genetically linked to either the N-terminal or C-terminal of either the heavy or light chain were engineered. Only the C-terminal variants expressed the full-length molecule. An in vitro assessment of the biological activity of VB6-845 showed that it bound and selectively killed EpCAM-positive cell lines with a greater potency than many commonly used chemotherapeutic agents. In vivo efficacy was demonstrated using an EpCAM-positive human tumor xenograft model in SCID mice with the majority of the mice treated being tumor free at the end of the study.

Antitumor and immunomodulating effects of polysaccharides isolated from Solanum nigrum Linne.

We have examined the effects of the crude polysaccharides isolated from Solanum nigrum Linne (SNL-P) in vitro and in vivo against U14 cervical cancer. SNL-P showed no antiproliferative effects in vitro at a dose up to 1 mg/ml. In vivo administration with SNL-P (90, 180, 360 mg/kg b.w., p.o.) decreased the number of ascites tumor cells and prolonged the survival time of U14 cervical-cancer-bearing mice. FACScan flow cytometer analysis showed that most of the ascites tumor cells were arrested in G2/M phase of cell cycle and the ratio of CD4+/CD8+ peripheral blood T-lymphocyte subpopulations were restored following treatment of SNL-P. Furthermore, the treatment with SNL-P also caused a significant increment in IFN-gamma (p < 0.01, 90, 180 and 360 mg/kg b.w.) and a remarkable decrease in Il-4 (p < 0.01, 90, 180 mg/kg b.w.; p < 0.05, 360 mg/kg b.w.) by the method of ELISA. These data showed that SNL-P possess potent antitumor activity and SNL-P might exert antitumor activity via activation of different immune responses in the host rather than by directly attacking cancer cells on the U14 cervical cancer bearing mice. Thus, SNL-P could be used as an immunomodulator and an anticancer agent.