Therapeutic administration of a synthetic CpG oligodeoxynucleotide triggers formation of anti-CpG antibodies

An Open-Label Study of Subcutaneous CpG Oligodeoxynucleotide (PF03512676) in Combination with Trastuzumab in Patients with Metastatic HER2+ Breast Cancer

OBJECTIVES

CpG ODN is a Toll-like receptor 9 agonist with immunotherapeutic potential for many cancer types, including aggressive breast cancers. There is strong interest in utilizing CpG ODN as an adjuvant to improve clinical efficacy of current treatments and immunogenicity of breast cancers not traditionally responsive to active immunotherapy, such as those that are human epidermal growth factor receptor 2 (HER2)-positive. This study aimed to study the efficacy and safety of combination CpG ODN plus anti-HER2 antibody trastuzumab treatment in patients with advanced/metastatic breast cancer.

METHODS

This single-arm, open-label phase II clinical trial treated patients (n = 6) with advanced/metastatic HER2-positive breast cancer with weekly subcutaneous CpG ODN and trastuzumab. Patients may have received any number of prior therapies to be enrolled (most enrolled at median 1 prior line of chemotherapy). Peripheral blood was collected at baseline and weeks 2, 6, 12, and 18 for immune analyses. Six patients were enrolled and 50% achieved stable disease (SD) response.

RESULTS

Median PFS was 8.3 months. Three of the six patients enrolled opted to stop treatment due to tolerability issues. Multiplex assay for cytokine measurements revealed significantly higher VEGF-D levels at week 2 compared to baseline. Peripheral blood mononuclear cells analyzed by flow cytometry showed a significant increase in monocytic MDSC between weeks 6 and 12. Patients with progressive disease tended to have higher levels of week 6 monocytic MDSC and PD-1+ T cells than patients with SD. NK cell populations did not significantly change throughout treatment.

CONCLUSIONS

CpG ODN and trastuzumab treatment of metastatic HER2 + breast cancer was safe but was not tolerable for all patients. This combination did induce potentially predictive immune profile changes in treated patients with metastatic HER2 + breast cancer, the significance of which needs to be further explored.

Maximizing TLR9 Activation in Cancer Immunotherapy with Dual-Adjuvanted Spherical Nucleic Acids

Nucleic-acid-based immune adjuvants have been extensively investigated for the design of cancer vaccines. However, nucleic acids often require the assistance of a carrier system to improve cellular uptake. Yet, such systems are prone to carrier-associated adaptive immunity, leading to difficulties in a multidose treatment regimen. Here, we demonstrate that a spherical nucleic acid (SNA)-based self-adjuvanting system consisting of phosphodiester oligonucleotides and vitamin E can function as a potent anticancer vaccine without a carrier. The two functional modules work synergistically, serving as each other's delivery vector to enhance toll-like receptor 9 activation. The vaccine rapidly enters cells carrying OVA model antigens, which enables efficient activation of adaptive immunity in vitro and in vivo. In OVA-expressing tumor allograft models, both prophylactic and therapeutic vaccinations significantly retard tumor growth and prolong animal survival. Furthermore, the vaccinations were also able to reduce lung metastasis in a B16F10-OVA model.

Homotypic targeting of immunomodulatory nanoparticles for enhanced peripheral and central immunity

OBJECTIVES

Synthetic oligodeoxynucleotides (ODNs) that contain unmethylated cytosine-phosphate-guanine (CpG) motifs serve as immune adjuvants in disease treatment. However, the poor cell permeability and safety concerns limit their medical applications, and biocompatible strategies for efficient delivery of functional CpG ODNs are highly desirable.

MATERIALS AND METHODS

Self-assembled, cell membrane-coated CpG nanoparticles (NP) are prepared, and their physicochemical properties are characterized. The uncoated and membrane-coated CpG NP are compared for their biocompatibility, cellular uptake kinetics, endocytic pathways, subcellular localization, and immunostimulatory activities in macrophages and microglia.

RESULTS

Macrophage- or microglia-derived cell membrane camouflaging alters the endocytic pathways of CpG NP, promotes their targeted delivery to the cells with homologous membrane, ensures their endosomal localization, and enhances their immunomodulatory effects.

CONCLUSIONS

We design a type of biomimetic NP consisting of self-assembled CpG NP core and cell membrane shell, and demonstrate its advantages in the modulation of peripheral and central immune cells. Our study provides a new strategy for the application of CpG ODNs.

Microarray testing in patients with systemic lupus erythematosus identifies a high prevalence of CpG DNA-binding antibodies

Objective

Many autoantibodies are known to be associated with SLE, although their role in clinical practice is limited because of low sensitivity and weak associations with clinical manifestations. There has been great interest in the discovery of new autoantibodies to use in clinical practice. In this study, we investigated 57 new and known antibodies and their potential for diagnostics or risk stratification.

Methods

Between 2014 and 2017, residual sera of all anti-dsDNA tests in the UMC Utrecht were stored in a biobank. This included sera of patients with SLE, patients with a diagnosis of another immune-mediated inflammatory disease (IMID), patients with low (non-IMID) or medium levels of clinical suspicion of SLE but no IMID diagnosis (Rest), and self-reported healthy blood bank donors. Diagnosis and (presence of) symptoms at each blood draw were retrospectively assessed in the patient records with the Utrecht Patient-Oriented Database using a newly developed text mining algorithm. Sera of patients were analysed for the presence of 57 autoantibodies with a custom-made immunofluorescent microarray. Signal intensity cut-offs for all antigens on the microarray were set to the 95th percentile of the non-IMID control group. Differences in prevalence of autoantibodies between patients with SLE and control groups were assessed.

Results

Autoantibody profiles of 483 patients with SLE were compared with autoantibody profiles of 1397 patients from 4 different control groups. Anti-dsDNA was the most distinguishing feature between patients with SLE and other patients, followed by antibodies against Cytosine-phosphate-Guanine (anti-CpG) DNA motifs (p<0.0001). Antibodies against CMV (cytomegalovirus) and ASCA (anti-Saccharomyces cerevisiae antibodies) were more prevalent in patients with SLE with (a history of) lupus nephritis than patients with SLE without nephritis.

Conclusion

Antibodies against CpG DNA motifs are prevalent in patients with SLE. Anti-CMV antibodies are associated with lupus nephritis.

Targeting Suppressive Oligonucleotide to Lymph Nodes Inhibits Toll-like Receptor-9-Mediated Activation of Adaptive Immunity

PURPOSE

This paper aims to investigate the immunoinhibitory properties of a lymph nodes-targeting suppressive oligonucleotide (ODN) for the potential treatment of autoimmune diseases or chronic inflammation.

METHODS

Synthetic suppressive ODN engineered with an albumin-binding diacyl lipid at the 5'-terminal (lipo-ODN) was synthesized. In vitro and in vivo experiments were designed to compare the immune suppressive properties of lipo-ODN and unmodified ODN. Cellular uptake and distribution, inhibition of Toll-like receptor (TLR) activation, lymph nodes (LN) draining, and the suppression of antigen-specific immune responses in an ovalbumin protein model was investigated.

RESULTS

Compared to unmodified ODN, lipid functionalized suppressive ODN demonstrated enhanced cellular uptake and TLR-9 specific immune suppression in TLR reporter cells. Additionally, injection of a low dose of lipid-modified suppressive ODN, but not the unconjugated ODN, accumulated in the draining LNs and exhibited potent inhibition of antigen-specific CD8⁺ T cell and B cell responses in vivo.

CONCLUSIONS

Targeting suppressive ODN to antigen presenting cells (APCs) in the local LNs is an effective approach to amplify the immune modulation mediated by ODN containing repetitive TTAGGG motif. This approach might be broadly applicable to target molecular adjuvants to the key immune cells in the LNs draining from disease site, providing a simple strategy to improve the efficacy of many molecular immune modulators.

Oligonucleotide-Based Drug Development: Considerations for Clinical Pharmacology and Immunogenicity

The field of oligonucleotide (OGN)-based therapeutics has been growing dramatically in the past decade, providing innovative platforms to develop agents for the treatment of a wide variety of clinical conditions. OGN agents have unique physicochemical properties and pharmacokinetic/pharmacodynamic characteristics. This review considers findings from the literature and information on new molecular entities submitted to the US Food and Drug Administration as OGN-based therapeutics. In addition, the article discusses several challenging issues from the perspective of clinical pharmacology, emphasizing the potential of immunogenicity, the effect of renal impairment on OGN exposure, drug-drug interactions, and the utility of pharmacokinetic/pharmacodynamic modeling. The field of OGN-based therapeutics is in evolution and will benefit from further studies as well as clinical experience to formulate guidelines and promote the development of this class of agents.

Isolation of Foreign Material-Free Endothelial Progenitor Cells Using CD31 Aptamer and Therapeutic Application for Ischemic Injury

Endothelial progenitor cells (EPCs) can be isolated from human bone marrow or peripheral blood and reportedly contribute to neovascularization. Aptamers are 40-120-mer nucleotides that bind to a specific target molecule, as antibodies do. To utilize apatmers for isolation of EPCs, in the present study, we successfully generated aptamers that recognize human CD31, an endothelial cell marker. CD31 aptamers bound to human umbilical cord blood-derived EPCs and showed specific interaction with human CD31, but not with mouse CD31. However, CD31 aptamers showed non-specific interaction with CD31-negative 293FT cells and addition of polyanionic competitor dextran sulfate eliminated non-specific interaction without affecting cell viability. From the mixture of EPCs and 293FT cells, CD31 aptamers successfully isolated EPCs with 97.6% purity and 94.2% yield, comparable to those from antibody isolation. In addition, isolated EPCs were decoupled from CD31 aptamers with a brief treatment of high concentration dextran sulfate. EPCs isolated with CD31 aptamers and subsequently decoupled from CD31 aptamers were functional and enhanced the restoration of blood flow when transplanted into a murine hindlimb ischemia model. In this study, we demonstrated isolation of foreign material-free EPCs, which can be utilized as a universal protocol in preparation of cells for therapeutic transplantation.

Inhibitory/suppressive oligodeoxynucleotide nanocapsules as simple oral delivery devices for preventing atopic dermatitis in mice

Here, we report a simple and low-cost oral oligodeoxynucleotide (ODN) delivery system targeted to the gut Peyer's patches (PPs). This system requires only Dulbecco's modified eagle's medium, calcium chloride, ODNs, and basic laboratory equipment. ODN nanocapsules (ODNcaps) were directly delivered to the PPs through oral administration and were taken up by macrophages in the PPs, where they induced an immune response. Long-term continuous oral dosing with inhibitory/suppressive ODNcaps (iODNcaps, "iSG3caps" in this study) was evaluated using an atopic dermatitis mouse model to visually monitor disease course. Administration of iSG3caps improved skin lesions and decreased epidermal thickness. Underlying this effect is the ability of iSG3 to bind to and prevent phosphorylation of signal transducer and activator of transcription 6, thereby blocking the interleukin-4 signaling cascade mediated by binding of allergens to type 2 helper T cells. The results of our iSG3cap oral delivery experiments suggest that iSG3 may be useful for treating allergic diseases.

Effective CpG DNA delivery using amphiphilic cycloamylose nanogels

Unmethylated CpG oligodeoxynucleotides induce inflammatory immune responses through cytokine production and have attracted increasing attention as an immunostimulator. However, there remains a challenging issue of the use of 'native CpG DNA'. In the present study, we prepared cationic nanometer-sized gels (nanogels) consisting of cycloamylose modified with cholesterol and diethylaminoethane to form hydrophobic cross-linking points and to add positively charged groups, respectively. The cationic nanogels and native CpG DNA formed nanometer-sized complexes. Complexes of native CpG DNA with cationic nanogels delivered native CpG DNA to macrophage-like cells and induced cytokine production. In addition, complexes of negative control oligonucleotides with cationic nanogels did not induce cytokine production, and the induction of cytokines using complexes of phosphorothioate-modified CpG with cationic nanogels was lower than that of native CpG DNA. These results suggest that the complex of native CpG DNA with cationic nanogels is a promising strategy for nucleic acid adjuvants.

Improving the Th1 cellular efficacy of the lead Yersinia pestis rF1-V subunit vaccine using SA-4-1BBL as a novel adjuvant

The lead candidate plague subunit vaccine is the recombinant fusion protein rF1-V adjuvanted with alum. While alum generates Th2 regulated robust humoral responses, immune protection against Yersinia pestis has been shown to also involve Th1 driven cellular responses. Therefore, the rF1-V-based subunit vaccine may benefit from an adjuvant system that generates a mixed Th1 and humoral immune response. We herein assessed the efficacy of a novel SA-4-1BBL costimulatory molecule as a Th1 adjuvant to improve cellular responses generated by the rF1-V vaccine. SA-4-1BBL as a single adjuvant had better efficacy than alum in generating CD4(+) and CD8(+) T cells producing TNFα and IFNγ, signature cytokines for Th1 responses. The combination of SA-4-1BBL with alum further increased this Th1 response as compared with the individual adjuvants. Analysis of the humoral response revealed that SA-4-1BBL as a single adjuvant did not generate a significant Ab response against rF1-V, and SA-4-1BBL in combination with alum did not improve Ab titers. However, the combined adjuvants significantly increased the ratio of Th1 regulated IgG2c in C57BL/6 mice to the Th2 regulated IgG1. Finally, a single vaccination with rF1-V adjuvanted with SA-4-1BBL+alum had better protective efficacy than vaccines containing individual adjuvants. Taken together, these results demonstrate that SA-4-1BBL improves the protective efficacy of the alum adjuvanted lead rF1-V subunit vaccine by generating a more balanced Th1 cellular and humoral immune response. As such, this adjuvant platform may prove efficacious not only for the rF1-V vaccine but also against other infections that require both cellular and humoral immune responses for protection.

Injectable, self-gelling, biodegradable, and immunomodulatory DNA hydrogel for antigen delivery

DNA nanotechnology-based nanosystems and macrosystems have attracted much attention in the biomedical research field. The nature of DNA endows these systems with biodegradable, biocompatible, and immunomodulatory properties. Here, we present an injectable hydrogel system that consists only of chemically synthesized short DNA strands, water, and salts. Several preparations of polypod-like structured DNA, or polypodna, were designed, including tri-, tetra-, penta- and hexapodna, as the building blocks of self-gelling DNA hydrogel. Under physiological conditions, properly designed polypodna preparations formed a hydrogel. The analysis of the modulus data of the hydrogel consisting of two sets of hexapodna preparations showed that this injectable hydrogel was reorganized at a time scale of 0.25s. Then, DNA hydrogel containing unmethylated cytosine-phosphate-guanine (CpG) dinucleotides was used to stimulate innate immunity through Toll-like receptor 9, the receptor for CpG DNA. Gel formation significantly increased the activity of immunostimulatory CpG DNA, retarded the clearance after intradermal injection into mice, and increased the immune responses to ovalbumin (OVA) incorporated into the hydrogel as a model antigen. OVA/CpG DNA hydrogel induced much less local or systemic adverse reactions than OVA injected with complete Freund's adjuvant or alum. GpC DNA hydrogel containing no CpG sequences was less effective, indicating the importance of immunomodulation by CpG DNA hydrogel. Thus, we have created an efficient system for sustained delivery of antigens or other bioactive compounds.

Recent progress concerning CpG DNA and its use as a vaccine adjuvant

CpG Oligonucleotides (ODN) are immunomodulatory synthetic oligonucleotides designed to specifically agonize Toll-like receptor 9. Here, we review recent progress in understanding the mechanism of action of CpG ODN and provide an overview of human clinical trial results using CpG ODN to improve the vaccines for cancer, allergy and infectious disease.

Potential capacity of aptamers to trigger immune activation in human blood

Target specific short single-stranded DNA (ssDNA) molecules, called aptamers, are auspicious ligands for numerous in vivo applications. However, aptamers are synthetic molecules, which might be recognized by the immune cells in vivo and induce an activation of the innate immune system. Thus, immune activation potential of synthetic ssDNA oligonucleotides (ODNs) was determined using a well established closed-loop circulation model. Fresh human blood was incubated at 37°C for 2 or 4 hours with ssDNA ODNs (SB_ODN) or CpG ODN as positive control. Transcriptional changes were determined by microarray analyses. Blood samples containing SB_ODN demonstrated after 4 hours a significant regulation of 295 transcripts. Amongst others, CCL8, CXCL10, CCL7 and CXCL11 were highest regulated genes. Gene Ontology terms and KEGG pathway analyses exhibited that the differentially expressed genes belong to the transcripts that are regulated during an immune and inflammatory response, and were overrepresented in TLR signaling pathway. This study shows for the first time the potential of aptamers to activate immune system after systemic application into the human blood. Thus, we highly recommend performing of these preclinical tests with potential aptamer-based therapeutics.

Trial Watch: Toll-like receptor agonists for cancer therapy

Toll-like receptors (TLRs) have long been known for their ability to initiate innate immune responses upon exposure to conserved microbial components such as lipopolysaccharide (LPS) and double-stranded RNA. More recently, this family of pattern recognition receptors has been attributed a critical role in the elicitation of anticancer immune responses, raising interest in the development of immunochemotherapeutic regimens based on natural or synthetic TLR agonists. In spite of such an intense wave of preclinical and clinical investigation, only three TLR agonists are currently licensed by FDA for use in cancer patients: bacillus Calmette–Guérin (BCG), an attenuated strain of Mycobacterium bovis that operates as a mixed TLR2/TLR4 agonist; monophosphoryl lipid A (MPL), a derivative of Salmonella minnesota that functions as a potent agonist of TLR4; and imiquimod, a synthetic imidazoquinoline that activates TLR7. One year ago, in the August and September issues of OncoImmunology, we described the main biological features of TLRs and discussed the progress of clinical studies evaluating the safety and therapeutic potential of TLR agonists in cancer patients. Here, we summarize the latest developments in this exciting area of research, focusing on preclinical studies that have been published during the last 13 mo and clinical trials launched in the same period to investigate the antineoplastic activity of TLR agonists.