Semisynthetic Saponin Research Articles

Adjuvant activity of tubeimosides by mediating the local immune microenvironment.

Rhizoma Bolbostemmatis, the dry tuber of Bolbostemma paniculatum, has being used for the treatment of acute mastitis and tumors in traditional Chinese medicine. In this study, tubeimoside (TBM) I, II, and III from this drug were investigated for the adjuvant activities, structure-activity relationships (SAR), and mechanisms of action. Three TBMs significantly boosted the antigen-specific humoral and cellular immune responses and elicited both Th1/Th2 and Tc1/Tc2 responses towards ovalbumin (OVA) in mice. TBM I also remarkably facilitated mRNA and protein expression of various chemokines and cytokines in the local muscle tissues. Flow cytometry revealed that TBM I promoted the recruitment and antigen uptake of immune cells in the injected muscles, and augmented the migration and antigen transport of immune cells to the draining lymph nodes. Gene expression microarray analysis manifested that TBM I modulated immune, chemotaxis, and inflammation-related genes. The integrated analysis of network pharmacology, transcriptomics, and molecular docking predicted that TBM I exerted adjuvant activity by interaction with SYK and LYN. Further investigation verified that SYK-STAT3 signaling axis was involved in the TBM I-induced inflammatory response in the C2C12 cells. Our results for the first time demonstrated that TBMs might be promising vaccine adjuvant candidates and exert the adjuvant activity through mediating the local immune microenvironment. SAR information contributes to developing the semisynthetic saponin derivatives with adjuvant activities.

Potentiating pneumococcal glycoconjugate vaccine PCV13 with saponin adjuvant VSA-1.

VSA-1 is a semisynthetic saponin adjuvant prepared from naturally occurring Momordica saponin and capable of stimulating antigen-specific humoral and cellular immune responses. Its immunostimulating activity in enhancing the immune responses induced by the clinical glycoconjugate pneumococcal vaccine PCV13 is compared with QS-21 in female BALB/c mice. Both VSA-1 and QS-21 boosted IgG and opsonic antibodies titers against seven selected serotypes, including serotypes 3, 14, and 19A that are involved in most PCV13 breakthroughs. Since VSA-1 is much more accessible and of lower toxicity than QS-21, it can be a practical saponin immunostimulant to be included in a new glycoconjugate pneumococcal vaccine formulation.

Structure-Activity Relationship Study of Momordica Saponin II Derivatives as Vaccine Adjuvants.

VSA-2 is a recently developed semisynthetic saponin immunostimulant. It is prepared by incorporating a terminal-functionalized side chain to the branched trisaccharide domain at the C3 position of Momordica saponin II (MS II) isolated from the seeds of perennial Momordica cochinchinensis Spreng. Direct comparison of VSA-2 and the clinically proven saponin adjuvant QS-21 shows that VSA-2 is comparable to QS-21 in enhancing humoral and cellular immune responses. Structure-activity relationship studies show that structural changes in the side chain have a significant impact on saponins' adjuvant activity. However, with the VSA-2 molecular framework intact, the new VSA-2 analogues with various substitution(s) at the terminal benzyl group of the side chain retain the ability of potentiating antigen-specific humoral and cellular responses.

1238. The Novel Semisynthetic Saponin Adjuvant TQL1055 Enhances the Antibody Response to Pertussis Vaccine with an Improved Tolerability Profile over QS-21

BackgroundAcellular pertussis vaccines are better tolerated but less immunogenic than older whole cell vaccines. Novel adjuvants may be useful to enhance their immunogenicity. First-generation natural saponins are potent immuno-enhancers but are highly reactogenic. The novel semisynthetic saponin TQL1055 was evaluated for its potential to enhance the immunogenicity of a commercially available acellular pertussis vaccine as part of a National Institute of Allergy and Infectious Disease (NIAID) funded project.MethodsGroups of 10 female C57BL/6J mice were immunized subcutaneously (SC) with Adacel® (containing 0.5 mcg pertussis toxin antigen) alone or in combination with QS-21 at 20 mcg/dose or TQL1055 at 50 mcg/dose on Days 0 and 28. Serum antibody titer to pertussis antigen was determined by ELISA (Alpha Diagnostics) at Days 0, 28, and 42 and geometric mean titers (GMT) in IU/mL were determined. Body weights were measured serially for 7 days after dose 1.ResultsAt 28 days following dose 1, mice receiving TQL1055 had an anti-pertussis toxin IgG GMT of 8492, compared with 2263 in mice receiving QS-21 (p = 0.005). At Day 42, 14 days after dose 2, the GMTs increased to 18719 in the TQL1055 group and 10851 in the QS-21 group (p = 0.0653 vs TQL1055 dose 2; p = 0.6038 vs TQL1055 dose 1). Mice in the Adacel and TQL1055 groups gained weight steadily after dose 1, while mice in the QS-21 group had an average weight loss of 10% from baseline at 3 days after dose 1 (p < 0.0001).Figure 1: TQL1055 Enhances the Antibody Response to Adacel® (Commercial Acellular Pertussis Vaccine) in C57BL/6J Female Mice Figure 2: TQL1055 Shows Enhanced Tolerability (measured by decreased weight loss) Compared to QS-21 Following Subcutaneous Injection in C57BL/6J Female Mice ConclusionTQL1055 enhanced the antibody response to a commercial acellular pertussis vaccine to a greater degree than QS-21. Additionally, TQL1055 was better tolerated than QS-21, with no weight loss after vaccination. These findings suggested that TQL1055 may improve the performance of acellular pertussis vaccines without an increase in reactogenicity.DisclosuresChloe Buzz, BS, Adjuvance Technologies (Employee) Sean R. Bennett, MD PhD, Adjuvance Technologies (Employee) Phil Livingston, MD, Adjuvance Technologies (Consultant, Shareholder) Eric Farris, PhD, Adjuvance Technologies (Employee) Tyler Martin, MD, Adjuvance Technologies (Employee, Shareholder)

1237. Robust Adjuvant Activity and Dose-sparing Potential of the Novel Semisynthetic Saponin Adjuvant TQL1055 for Seasonal and Pandemic Influenza

BackgroundVaccination against both seasonal and pandemic influenza requires effective adjuvants to maximize the utility of limited antigen and to enhance immunogenicity in hyporesponsive at-risk populations. First-generation natural saponins are potent immuno-enhancers but are reactogenic and have supply constraints. As part of a NIH-funded project, the novel semisynthetic saponin TQL1055 was evaluated for its potential to augment the immunogenicity of influenza antigens.Figure 1: TQL1055 Enhances the Antibody Response to a Recombinant Antigen Influenza Vaccine (Flublok®) and Exhibits Antigen Dose-Sparing Effects Figure 2: TQL1055 Exhibits Improved Systemic Tolerability Over QS-21. MethodsGroups of 10 C57BL/6J mice were immunized subcutaneously (SC) with Flublok® (H3N2 antigen) alone at either a 4.5 mcg or 1.1 mcg dose, or at a 1.1 mcg dose in combination with 10, 30 or 100 mcg TQL1055 on Days 0 and 21. Sera were analyzed at days 0, 21 and 42 by ELISA for H3N2-specific IgG. Body weights were measured serially.ResultsA 2-dose series of 1.1 mcg Flublok with TQL1055 elicited anti-H3N2 antibodies in all mice. This effect was TQL1055 dose-dependent, with GMTs of 2178 in the 10 mcg group, 13674 in the 30 mcg group and 48959 in the 100 mcg group. The GMT in all TQL1055 groups was higher than the GMT of 176 in the group receiving 4.5 mcg of Flublok alone. Mice receiving TQL1055 gained weight steadily after immunization, compared with a maximum weight loss of >10% in mice receiving 20 mcg of QS-21.ConclusionTQL1055 exhibits robust adjuvant activity for influenza antigens, demonstrating a dose-sparing effect and improved systemic tolerability compared with QS-21. Taken together, these finding support further evaluation of its potential as an adjuvant for influenza vaccines.DisclosuresChloe Buzz, BS, Adjuvance Technologies (Employee) Eric Farris, PhD, Adjuvance Technologies (Employee) Sean R. Bennett, MD PhD, Adjuvance Technologies (Employee) Pat Frenchick, PhD, Adjuvance Technologies (Consultant) Tyler Martin, MD, Adjuvance Technologies (Employee, Shareholder)

Synthesis, Modification and Biological Activity of Diosgenyl β-d-Glycosaminosides: An Overview.

Saponins are a structurally diverse class of natural glycosides that possess a broad spectrum of biological activities. They are composed of hydrophilic carbohydrate moiety and hydrophobic triterpenoid or steroid aglycon. Naturally occurring diosgenyl glycosides are the most abundant steroid saponins, and many of them exhibit various pharmacological properties. Herein, we present an overview of semisynthetic saponins syntheses–diosgenyl β-d-glycosaminosides (d-gluco and d-galacto). These glycosides possess a 2-amino group, which creates great possibilities for further modifications. A wide group of glycosyl donors, different N-protecting groups and various reaction conditions used for their synthesis are presented. In addition, this paper demonstrates the possibilities of chemical modifications of diosgenyl β-d-glycosaminosides, associated with functionalisation of the amino group. These provide N-acyl, N-alkyl, N,N-dialkyl, N-cinnamoyl, 2-ureido and 2-thiosemicarbazonyl derivatives of diosgenyl β-d-glycosaminosides, for which the results of biological activity tests (antifungal, antibacterial, anti-cancer and hemolytic) are presented.

Identification of a Noncanonical Necrotic Cell Death Triggered via Enhanced Proteolysis by a Novel Sapogenol Derivative.

Small molecules which activate distinct cell death pathways have promising high potential for anticancer drug research. Especially, regulated necrosis draws attention as an alternative cell death mechanism to overcome the drug resistance. Here, we report that a new semisynthetic saponin analogue (AG-08) triggers necrotic cell death with unprecedented pathways. AG-08-mediated necrosis depends on enhanced global proteolysis involving calpains, cathepsins, and caspases. Moreover, AG-08 generates several alterations in lysosomal function and physiology including membrane permeabilization, redistribution toward the perinuclear area, and lastly excessive tubulation. As a consequence of lysosomal impairment, the autophagic process was abolished via AG-08 treatment. Collectively, in addition to its ability to induce necrotic cell death, which makes AG-08 a promising candidate to cope with drug resistance, its unique activity mechanisms including autophagy/lysosome impairment and enhancement of proteolysis leading a strong death capacity emphasizes its potential for anticancer drug research.

Structural Effect on Adjuvanticity of Saponins.

We have prepared a number of saponin-based vaccine adjuvant candidates. These unnatural saponins have a different terminal-functionalized side chain incorporated into the glucuronic acid unit that is attached to a triterpenoid core at its C3 position. The semisynthetic saponin adjuvants have shown significantly different immunostimulatory activities, suggesting that the structure of the side chain, triterpenoid core, and oligosaccharide domain together orchestrate saponin adjuvant's potentiation of immune responses. Among these new adjuvant candidates, VSA-2 (5b), a derivative of Momordica saponin (MS) II, showed consistent enhancement of immunoglobulin G2a (IgG2a) production when it was in formulation with either ovalbumin or recombinant hemagglutinin B (rHagB) antigen. With rHagB antigen, it induced a significantly higher IgG2a response than the positive control GPI-0100, a well-studied semisynthetic saponin adjuvant mixture derived from Quillaja saponaria Molina saponins, known for its ability to induce a balanced Th1/Th2 immunity. These results confirm that Momordica saponins are a viable natural source to provide potent saponin adjuvants after simple chemical derivatization and identify VSA-2 (5b) as another MS-based promising immunostimulant lead owing to its distinctive ability in potentiating the IgG2a response.

An investigation of the antileishmanial properties of semi-synthetic saponins.

Leishmaniasis is a neglected tropical disease caused by insect-vector borne protozoan parasites of the, Leishmania species. Whilst infection threatens and affects millions of the global poor, vaccines are absent and drug therapy limited. Extensive efforts have recently been made to discover new leads from small molecule synthetic compound libraries held by industry; however, the number of new chemical entities identified and entering development as anti-leishmanials has been very low. This has led to increased interest in the possibility of discovering naturally derived compounds with potent antileishmanial activity which may be developed towards clinical applications. Plant-derived triterpenoid and steroidal saponins have long been considered as anti-microbials and here we describe an investigation of a library of 137 natural (9) and semi-synthetic saponins (128) for activity against Leishmania mexicana, a causative agent of cutaneous leishmaniasis. The triterpenoid sapogenin, hederagenin, readily obtained in large quantities from Hedera helix (common ivy), was converted into a range of 128 derivatives. These semi-synthetic compounds, as well as saponins isolated from ivy, were examined with a phenotypic screening approach to identify potent and selective anti-leishmanial hits. This led to the identification of 12 compounds, including the natural saponin gypsogenin, demonstrating high potency (ED50 < 10.5 μM) against axenic L. mexicana amastigotes, the mammalian pathogenic form. One of these, hederagenin disuccinate, was sufficiently non-toxic to the macrophage host cell to facilitate further analyses, selectivity index (SI) > 10. Whilst this was not active in an infected cell model, the anti-leishmanial properties of hederagenin-derivatives have been demonstrated, and the possibility of improving the selectivity of natural hederagenin through chemical modification has been established.

N-Aminoacyl and N-hydroxyacyl derivatives of diosgenyl 2-amino-2-deoxy-β-d-glucopyranoside: Synthesis, antimicrobial and hemolytic activities

Diosgenyl 2-amino-2-deoxy-β-d-glucopyranoside is a semisynthetic saponin with antimicrobial and antitumor activities. To search for more effective analogues, N-aminoacyl and N-hydroxyacyl derivatives of this saponin were synthesized conventionally and with microwave assistance, and tested against the human pathogenic fungi and Gram-positive and Gram-negative bacteria. None of the tested compounds exhibit activity against Gram-negative bacteria. Almost all of the synthesized N-aminoacyl saponins exhibit antifungal activity and act effectively against Gram-positive bacteria, some better than the parent compound. The best acting saponins are the same size and possess sarcosine or l- or d-alanine attached to the parent glucosaminoside. Shorter and longer aminoacyl residues are less advantageous. d-Alanine derivative is the most effective against Gram positive bacteria. Structure-activity relationship (SAR) analysis indicates that the free α-amino group in aminoacyl residue is necessary for antimicrobial activities of the tested saponins. (N-Acetyl)aminoacyl and N-hydroxyacyl analogs are inactive. Measurements of the hemolytic activities demonstrate that the best acting saponins are not toxic towards human red blood cells.

Influenza virosomes supplemented with GPI-0100 adjuvant: a potent vaccine formulation for antigen dose sparing

Adjuvants can stimulate vaccine-induced immune responses and can contribute decisively to antigen dose sparing when vaccine antigen production is limited, as for example during a pandemic influenza outbreak. We earlier showed that GPI-0100, a semi-synthetic saponin derivative with amphiphilic structure, significantly stimulates the immunogenicity and protective efficacy of influenza subunit vaccine administered via a systemic route. Here, we evaluated the adjuvant effect of GPI-0100 on a virosomal influenza vaccine formulation. In contrast to influenza subunit vaccine adjuvanted with GPI-0100, virosomal vaccine supplemented with the same dose of GPI-0100 provided full protection of mice against infection at the extremely low antigen dose of 2 × 8 ng hemagglutinin. Overall, adjuvanted virosomes elicited higher antibody and T-cell responses than did adjuvanted subunit vaccine. The enhanced immunogenicity of the GPI-0100-adjuvanted virosomes, particularly at low antigen doses, is possibly due to a physical association of the amphiphilic adjuvant with the virosomal membrane. These results show that a combination of GPI-0100 and a virosomal influenza vaccine formulation is highly immunogenic and allows the use of very low antigen doses without compromising the protective potential of the vaccine.

Evaluation of novel saponins from Psammosilene tunicoides and their analogs as immunomodulators

Two original oleanane-type triterpenoid saponins, tunicosaponin A (TSA) and tunicosaponin E (TSE) were isolated from the roots of Psammosilene tunicoides. Four semi-synthetic saponin derivatives, TSA1, TSA2, TSA3, and TSA4, were synthesized from TSA; two derivatives TSE1 and TSE2 were prepared from TSE. Through comparing their hemolytic activity and effects on ovalbumin (OVA)-induced IgG response with those of Quil A, TSA2 was selected as a lead candidate to evaluate acute and hepatotoxic toxicities and adjuvant potentials on the cellular and humoral immune responses of ICR mice against OVA. TSA2 had lower hemolytic activity than Quil A and TSA (P<0.001). Furthermore, TSA2 did not cause any mortality and side effects when mice were administered subcutaneously at a dose up to 1.6mg. Moreover, no significant hepatotoxic effect was observed in TSA2 groups in doses ranging from 0.05mg to 0.8mg. The Con A-, LPS-, and OVA-induced splenocyte proliferation, OVA-specific antibody levels (IgG, IgG1, IgG2a and IgG2b) and IFN-γ, TNF-α, IL-2, IL-4 and IL-5 in serum were significantly enhanced by TSA2 (25μg/mouse). The present study of structure–activity relationship indicates that the hydrophobicity of the ester/amide chains bonds to the carboxyl group of the glucuronic acid residue at position C-3 of the triterpene aglycone and the type of sugar chain at C-28 position of saponin could affect the potential of toxicity and adjuvant. Our findings demonstrate that TSA2 possesses higher adjuvant activities with less adverse effects and should be further explored as an immunomodulator for immune responses.

Preclinical evaluation of the saponin derivative GPI-0100 as an immunostimulating and dose-sparing adjuvant for pandemic influenza vaccines

With the current global influenza vaccine production capacity the large demand for vaccines in case of a pandemic can only be fulfilled when antigen dose sparing strategies are employed. Here we used a murine challenge model to evaluate the potential of GPI-0100, a semi-synthetic saponin derivative, to serve as a dose-sparing adjuvant for influenza subunit vaccine. Balb/c mice were immunized with different doses of A/PR8 (H1N1) subunit antigen alone or in combination with varying doses of GPI-0100. The addition of GPI-0100 significantly stimulated antibody and cellular immune responses, especially of the Th1 phenotype. Furthermore, virus titers detected in the lungs of mice challenged one week after the second immunization were significantly reduced among the animals that received GPI-0100-adjuvanted vaccines. Remarkably, adjuvantation of subunit vaccine with GPI-0100 allowed a 25-fold reduction in hemagglutinin dose without compromising the protective potential of the vaccine.

Abstract A138: Vaccination with HPV 16 L2E6E7 with GPI-0100 adjuvant elicits protective humoral as well as cell-mediated immune responses

Abstract A138 L1 virus-like particle (VLP) vaccines provide effective protection against Human papillomavirus (HPV) type from which the L1 was derived via the induction of neutralizing antibodies. While partial protection can occur against very closely related types, it is generally type-restricted and necessitates highly multivalent L1 VLP vaccines to obtain broad coverage. The minor capsid protein, L2, is emerging as an attractive alternative cross-protective antigen. Unfortunately, neither L1 VLP nor L2-based vaccines are effective against pre-existing disease, suggesting the need to develop therapeutic vaccines. Unlike the capsid proteins, the E6 and E7 oncoproteins are both required to maintain and expressed throughout cervical intraepithelial neoplasia (CIN) and cancer. TA-CIN, a vaccine comprising the HPV16 L2, E6 and E7 in a single tandem fusion protein, attempts to combine the advantages of broad cross-protection against HPV transmission with therapeutic responses targeting HPV16 early proteins. Here we test TA-CIN formulated along with GPI-0100, a semi-synthetic quillaja saponin analog, that was developed to promote both humoral and cellular immune responses. TA-CIN administered subcutaneously to mice three times at monthly intervals (125μg of clinical-grade protein) with 50μg GMP-grade GPI-0100 was found to elicit high titer antibodies that effectively neutralized not only HPV16 but also other oncogenic HPV types including HPV18, HPV31, HPV45, HPV58. Similarly, vaccination of pigtail macaques (Macaca nemestrina) with TA-CIN (three doses of 125μg of TA-CIN with 1000μg GMP-grade GPI-0100 at monthly intervals) was well tolerated and induced serum antibodies that neutralized HPV16, HPV18, and HPV31 in vitro. Notably, vaccination of mice with TA-CIN protected them from cutaneous HPV16 challenge as effectively as HPV16 L1 VLP. Combination of TA-CIN along with adjuvant GPI-0100 enhanced production of E7-specific, interferon gamma producing CD8+ T cell precursors by 20-fold. Vaccination with TA-CIN in adjuvant GPI-0100 completely prevented tumor growth after challenge with 5 x 104 HPV16-transformed TC-1 tumor cells. Protection of the mice immunized with TA-CIN plus GPI-0100 against TC-1 in a prophylactic setting was significantly more effective than TA-CIN alone or GPI-0100 alone. Patients vaccinated with TA-CIN alone develop weak HPV neutralizing antibody and E6/E7-specific T cell responses. GPI-0100 has been used safely as an adjuvant in several human trials suggesting that the combination of TA-CIN and GPI-0100 warrants further study. Citation Information: Cancer Prev Res 2008;1(7 Suppl):A138.

Evaluation of widely consumed botanicals as immunological adjuvants

Background Many widely used botanical medicines are claimed to be immune enhancers. Clear evidence of augmentation of immune responses in vivo is lacking in most cases. To select botanicals for further study based on immune enhancing activity, we study them here mixed with antigen and injected subcutaneously (s.c.). Globo H and GD3 are cell surface carbohydrates expressed on glycolipids or glycoproteins on the cell surface of many cancers. When conjugated to keyhole limpet hemocyanin (KLH), mixed with an immunological adjuvant and administered s.c. the magnitude of the antibody responses against globo H, GD3 and KLH depend largely on the potency of the adjuvant. We describe here the results obtained using this s.c. immunization model with seven botanicals purported to have immune stimulant effects. Methods Groups of 5–10 mice were immunized with globo H–KLH or GD3–KLH mixed with botanical, saline or positive control immunological adjuvant, s.c. three times at 1 week intervals. Antibody responses were measured 1 and 2 weeks after the 3rd immunization. The following seven botanicals and fractions were tested: (1) H-48 (Honso USA Co.), (2) Coriolus versicolor raw water extract, purified polysaccharide-K (PSK) or purified polysaccharide-peptide (PSP) (Institute of Chinese Medicine (ICM)), (3) Maitake extract (Yukiguni Maitake Co. Ltd. and Tradeworks Group), (4) Echinacea lipophilic, neutral and acidic extracts (Gaia Herbs), (5) Astragalus water, 50% or 95% ethanol extracts (ICM), (6) Turmeric supercritical (SC) or hydro-ethanolic (HE) extracts (New Chapter) or 60% ethanol extract (ICM) and (7) yeast β-glucan (Biotec Pharmacon). Purified saponin extract QS-21 (Antigenics) and semisynthetic saponin GPI-0100 (Advanced BioTherapies) were used as positive control adjuvants. Sera were analyzed by ELISA against synthetic globo H ceramide or GD3 and KLH. Results Consistent significant adjuvant activity was observed after s.c. vaccination with the Coriolus extracts (especially PSK), a 95% ethanol extract of Astragalus and yeast β-glucan, and (to a lesser extent) Maitake. Antibodies against KLH in all cases and against globo H in most cases were induced by these botanicals. Little or no adjuvant activity was demonstrated with H-48 or Echinacea extracts or the Astragalus water extract. Experiments with GD3–KLH as immunogen confirmed the adjuvant activity of the Coriolus, yeast β-glucan and Astragalus extracts. While extraction with ethanol concentrated the active ingredients in Astragalus, it had no impact on Coriolus where the 90% ethanol precipitate and solute were equally active. Conclusions Some, but not all, botanicals purported to be immune stimulants had adjuvant activity in our model. PSK and Astragalus were surprisingly active and are being further fractionated to identify the most active adjuvant components.

A new semisynthetic ocotillol-type saponin and resuscitation of haemorrhagic shock

A new ocotillol-type saponin (PGQ) has been semisynthesised from 20(S)-ginsenoside Rg3 for the first time, in with a yield of 73%, by oxidation and cyclisation of the side-chain. Its structure was characterised by IR, HR-MS, 1H NMR, 13C NMR, 1H-1H COSY, DEPT, HMBC and HMQC spectroscopy as 3-O-[β-d-glucopyranosyl-(1-2)-β-d-glucopyranosyl]-dammar- 20S,24S-epoxy-3β,12β,25-triol (1). The saponin produced a beneficial effect on resuscitation of haemorrhagic shock as follows: first, it could significantly rise increased mean arterial pressure; second, it could increased blood oxygen content; third, it could markedly decreased serum lipoperoxidase and increased superoxide dismutase (SOD) activities. Thus, the saponin had the effect of an anti-haemorrhagic shock.

A bivalent conjugate vaccine in the treatment of biochemically relapsed prostate cancer: a study of glycosylated MUC-2-KLH and Globo H-KLH conjugate vaccines given with the new semi-synthetic saponin immunological adjuvant GPI-0100 OR QS-21

GPI-0100 is a semi-synthetic saponin with modifications designed to augment stability and diminish toxicity. Two batches of GPI-0100 (the second with higher purity) were tested with doses ranging between 100 and 5000 μg in groups of five treated prostate cancer patients who had no evidence of disease except for rising PSA levels. GPI-0100 was mixed with a bivalent vaccine containing the glycolipid Globo H and the glycosylated mucin MUC2 conjugated to keyhole limpet hemocyanin (KLH). All doses were well tolerated and antibody titers against Globo H and MUC-2 escalated with the increasing dose levels. At the 5000 μg dose level in this patient population, toxicity remained minimal with only occasional grade II local toxicity at vaccination sites and occasional sporadic grade I elevations in ALT. Compared with a subsequent trial with the same bivalent vaccine plus QS-21 at the maximal tolerated dose of 100 μg, the 5000 μg dose of GPI-0100 produced comparable antibody titers.

Effect of immunological adjuvant combinations on the antibody and T-cell response to vaccination with MUC1–KLH and GD3–KLH conjugates

A year ago we described a comparison of 19 immunological adjuvants for their ability to augment antibody and T-cell responses against vaccines containing two cancer antigens, GD3 ganglioside and MUC1 peptide, covalently attached to keyhole limpet hemocyanin (KLH). As in our previous experience, the saponin fraction QS-21 was the most potent single adjuvant but several other adjuvants also had potent adjuvant activity. Induction of an immune response against cancer antigens is generally difficult because these antigens are autoantigens. To get maximal benefit from the adjuvant component of cancer vaccines we have now tested whether combinations of the optimal adjuvants induced an improved immune response compared to QS-21 alone. Since over the intervening year a new semi-synthetic saponin adjuvant (GPI-0100) containing the dodecylamide derivative of hydrolyzed naturally-occurring saponins had become available, this was tested as well. Twelve different adjuvant combinations and GPI-0100 were compared for their ability to augment (1) antibody responses against GD3 and MUC1 and (2) T-cell responses against GD3, MUC1 and KLH. GPI-0100 and five adjuvant combinations were superior to QS-21 alone for induction of IgM and IgG antibodies against MUC1 and/or GD3: QS-21 plus bacterial nucleotide CpG, QS-21 plus monophosphoryl lipid A (MPL), QS-21 plus non-ionic block copolymer CRL-1005, QS-21 plus Titermax and Titermax plus CpG. Antibody responses were documented both by ELISA against purified antigens and by FACS for cell surface reactivity. There was no evidence for T-cell immunity against GD3 or MUC1. The antibody responses against GD3 and MUC1 were, however, strongly correlated with IFN-γ release and DTH against KLH. These results demonstrate that combinations of immunological adjuvants are able to augment antibody and T-cell responses to these conjugates beyond that attainable with QS-21 alone, and again confirm the absolute necessity of potent adjuvants or adjuvant combinations for optimal immunogenicity with conjugate vaccines.

A semisynthetic Quillaja saponin as a drug delivery agent for aminoglycoside antibiotics.

The purpose of this study was to investigate the utility of a purified, semisynthetic saponin, DS-1, prepared by deacylation of a naturally occurring saponin from the bark of the Quillaja saponaria Molina tree, as a permeation enhancer for mucosal delivery of the aminoglycosides, gentamicin and tobramycin. Gentamicin or tobramycin formulations, with and without DS-1, were administered to rats nasally, ocularly, and rectally. Serum aminoglycoside levels following mucosal application were compared with those administered intramuscularly. Gentamicin formulations, with and without DS-1, were administered intranasally to mice 60 minutes after a lethal bacterial challenge. To ascertain nasal irritation potential, DS-1 nosedrops were administered to rats twice daily for 7 days in the right nostril only. Comparison of the left (internal control) and right nostril was made with a control group that received only buffer. Significant transport across mucous membranes was only observed in formulations containing DS-1. This effect on drug delivery was transient. Administration of an intranasal gentamicin/DS-1 formulation reversed the lethal bacterial challenge in mice, demonstrating that biological activity was retained after absorption. Nasal irritation was not observed in groups receiving DS-1 nosedrops, which were identical to control groups. DS-1 has potential as a transmucosal delivery agent for the aminoglycoside antibiotics.