Immune adjuvant therapy using Bacillus Calmette-Guérin cell wall skeleton (BCG-CWS) in advanced malignancies: A phase 1 study of safety and immunogenicity assessments

The cell wall skeleton of Bacillus Calmette-Guérin (BCG-CWS) is a bioactive component that is a strong immune adjuvant for cancer immunotherapy. BCG-CWS activates the innate immune system through various pattern recognition receptors and is expected to elicit antigen-specific cellular immune responses when co-administered with tumor antigens. To determine the recommended dose (RD) of BCG-CWS based on its safety profile, we conducted a phase I dose-escalation study of BCG-CWS in combination with WT1 peptide for patients with advanced cancer.The primary endpoint was the proportion of treatment-related adverse events (AEs) at each BCG-CWS dose. The secondary endpoints were immune responses and clinical effects. A BCG-CWS dose of 50, 100, or 200 μg/body was administered intradermally on days 0, 7, 21, and 42, followed by 2 mg of WT1 peptide on the next day. For the escalation of a dose level, 3 + 3 design was used.Study subjects were 18 patients with advanced WT1-expressing cancers refractory to standard anti-cancer therapies (7 melanoma, 5 colorectal, 4 hepatobiliary, 1 ovarian, and 1 lung). Dose-limiting toxicity occurred in the form of local skin reactions in 2 patients at a dose of 200 μg although no serious treatment-related systemic AEs were observed. Neutrophils and monocytes transiently increased in response to BCG-CWS. Some patients demonstrated the induction of the CD4 T cell subset and its differentiation from the naïve to memory phenotype, resulting in a tumor response.The RD of BCG-CWS was determined to be 100 μg/body. This dose was well tolerated and showed promising clinical effects with the induction of an appropriate immune response.

Enhancement of Th1 immune responses to recombinant influenza nucleoprotein by Ribi adjuvant

A broad coverage influenza vaccine against multiple viral strains based on the viral nucleoprotein (NP) is a goal pursued by many laboratories. If the goal is to formulate the vaccine with recombinant NP it is essential to count on adjuvants capable of inducing cellular immunity. This work have studied the effect of the monophosphoryl lipid A and trehalose dimycolate, known as the Ribi Adjuvant System (RAS), in the immune response induced in mice immunized with recombinant NP. The NP was formulated with RAS and used to immunize BALB/c mice. Immunizations with NP-RAS increased the humoral and cellular immune responses compared to unadjuvanted NP. The predominant antibody isotype was IgG2a, suggesting the development of a Th1 response. Analysis of the cytokines from mice immunized with NP-RAS showed a significant increase in the production of IFN-g and a decreased production of IL-10 and IL-4 compared to controls without RAS. These results are similar to those usually obtained using Freund’s adjuvant, known to induce Th1 and CTL responses when co-administered with purified proteins, and suggest that a similar approach may be possible to enhance the performance of a T-cell vaccine containing NP.

Evaluation of lipopolysaccharide and capsular polysaccharide as subunit vaccines against experimental melioidosis

Burkholderia pseudomallei is the causative agent of melioidosis, which is a major cause of morbidity and mortality in endemic regions. Currently there is no human vaccine against melioidosis. In this study, LPS or capsular polysaccharide was used to immunize BALB/c mice. The different polysaccharide antigens induced antibody responses. Mice vaccinated with LPS developed predominantly IgM and IgG3 responses. Contrastingly, mice vaccinated with capsular polysaccharide developed a predominantly IgG2b response. After immunization, mice were challenged by the intra-peritoneal route and an increased mean time to death was observed compared with unvaccinated controls. Immunization with LPS provided an optimal protective response. Mice challenged by the aerosol route showed a small increase in the mean time to death compared with the unvaccinated controls. The passive transfer of antigen from immunized into naïve mice provided protection against a subsequent challenge. This study is the first time antigens protective by active immunization have been identified and suggests that polysaccharides have potential as vaccine candidates against melioidosis.

Protective immunity to vaccinia virus induced by vaccination with multiple recombinant outer membrane proteins of intracellular and extracellular virions

Infectious intracellular and extracellular forms of vaccinia virus have different outer membrane proteins, presenting multiple targets to the immune system. We investigated the immunogenicity of soluble forms of L1, an outer membrane protein of the intracellular mature virus, and of A33 and B5, outer membrane proteins of the extracellular enveloped virus. The recombinant proteins, in 10-microg amounts mixed with a Ribi- or saponin-type adjuvant, were administered subcutaneously to mice. Antibody titers to each protein rose sharply after the first and second boosts, reaching levels that surpassed those induced by percutaneous immunization with live vaccinia virus. Immunoglobulin G1 (IgG1) antibody predominated after the protein immunizations, indicative of a T-helper cell type 2 response, whereas live vaccinia virus induced mainly IgG2a, indicative of a T-helper cell type 1 response. Mice immunized with any one of the recombinant proteins survived an intranasal challenge with 5 times the 50% lethal dose of the pathogenic WR strain of vaccinia virus. Measurements of weight loss indicated that the A33 immunization most effectively prevented disease. The superiority of protein combinations was demonstrated when the challenge virus dose was increased 20-fold. The best protection was obtained with a vaccine made by combining recombinant proteins of the outer membranes of intracellular and extracellular virus. Indeed, mice immunized with A33 plus B5 plus L1 or with A33 plus L1 were better protected than mice immunized with live vaccinia virus. Three immunizations with the three-protein combination were necessary and sufficient for complete protection. These studies suggest the feasibility of a multiprotein smallpox vaccine.

Enhancement of antigen-specific immunity via the TLR4 ligands MPL adjuvant and Ribi.529

MPL (Corixa) adjuvant is a chemically modified derivative of lipopolysaccharide that displays greatly reduced toxicity while maintaining most of the immunostimulatory activity of lipopolysaccharide. MPL adjuvant has been used extensively in clinical trials as a component in prophylactic and therapeutic vaccines targeting infectious disease, cancer and allergies. With over 33,000 doses administered to date, MPL adjuvant has emerged as a safe and effective vaccine adjuvant. Recently, scientists at Corixa Corporation have developed a library of synthetic lipid A mimetics (aminoalkyl glucosaminide 4-phosphates) with demonstrated immunostimulatory properties. Similar to MPL adjuvant, these synthetic compounds signal through Toll-like receptor 4 to stimulate the innate immune system. One of these compounds, Ribi.529 (RC-529), has emerged as a leading adjuvant with a similar efficacy and safety profile to MPL adjuvant in both preclinical and clinical studies.

Reduced cerebral infection of Neospora caninum-infected mice after vaccination with recombinant microneme protein NcMIC3 and ribi adjuvant

C57BL/6 mice were vaccinated with a bacterially expressed and purified polyhistidine-tagged full-length version of the microneme protein NcMIC3 (recNcMIC3) emulsified in Ribi Adjuvant System (RAS). Subsequently, they were challenged by intraperitoneal inoculation of 2 x 10(6) live Neospora caninum tachyzoites. As controls, groups of mice received phosphate-buffered saline (PBS)-RAS alone (adjuvant control) or were treated with PBS before infection (infection control). The protective effect of vaccination was assessed by Neospora-specific polymerase chain reaction (PCR), immunohistochemical investigation of brain tissue, and serological means (enzyme-linked immunosorbent assay). Assessment by PCR performed on DNA from different organs revealed that in all treatment groups parasite DNA could only be detected in brain tissue. According to the PCR results. the recNcMIC3 vaccine conferred protection to 75% of mice (n = 16 in 2 independent experiments), whereas application of PBS-RAS and of PBS alone resulted in protection of 12.5% and 0% of mice, respectively (n = 16 as above). Mice in the PBS-treated infection control group were affected by evident clinical signs of neosporosis starting on day 6 postinfection (p.i.). Conversely, none of the animals treated with either PBS-RAS or recNcMIC3 exhibited any symptoms until day 21 p.i. Immunohistochemical staining of paraffin-embedded brain tissue sections confirmed the protective effect of recNcMIC3 vaccination. Quantitative Neospora-specific real-time PCR revealed that infection intensities were lower in the brain tissues of recNcMIC3-vaccinated mice compared with PBS-RAS-treated adjuvant control mice. Serological analysis showed that the protective effect observed in recNcMIC3-vaccinated mice was associated with a Th2-type IgG1 antibody response directed against native NcMIC3 and a mixed IgG1-IgG2a antibody response directed against the recombinant antigen itself. Taken together, these results demonstrated that recombinant NcMIC3 vaccine confers a significant protectivity against experimentally induced cerebral neosporosis in mice.

Antigenicity of Mycobacterium paratuberculosis superoxide dismutase in mice

Mycobacterium paratuberculosis (MPT) is the etiologic agent of paratuberculosis. The disease is prevalent in cattle worldwide, and exacts a heavy financial toll. Effective control requires the development of acellular vaccines offering a better protection than the current available vaccines without side effects and allowing the discrimination between infected and vaccinated animals. We studied the immune response of mice to the MPT superoxide dismutase (SOD) alone or adjuvanted by Ribi. We cloned, overexpressed and purified this antigen in Escherichia coli. Spleen cells from immunized mice, after exposure to recombinant MPT SOD (MPT rSOD), produced significant levels of IFNgamma, TNFalpha and IL-6. IFNgamma and TNFalpha production was increased by the addition of Ribi. In contrast, low levels of NO, IL-4 and IL-10 were secreted by spleen cells culture from immunized mice. The immunoglobulin isotype distribution analysis showed that Ribi adjuvant clearly induced a significantly higher anti-MPT rSOD antibody production of all classes tested and decreased the IgG1/IgG2a ratio thus improving the Th1 response. Delayed-type hypersensitivity responses in mice footpads were observed only in mice immunized with MPT rSOD emulsified in Ribi. Vaccination of MPT rSOD emulsified with Ribi induced both a Th2 and Th1 type of immune response with the later slightly more pronounced. The results presented here on the immunogenicity of MPT SOD suggest that this antigen should be further tested as a candidate antigen for a future acellular vaccine against paratuberculosis.

Immune responses and side effects of five different oil-based adjuvants in mice

In this study, five different oil based adjuvants were compared to assess efficacy and side effects. Mice were injected subcutaneously (s.c.) or intraperitoneally (i.p.) with a weak immunogen (synthetic peptide) emulsified in Freund's adjuvant (FA), Specol, RIBI, TiterMax or Montanide ISA50. Efficacy of adjuvants was evaluated based on their properties to induce peptide specific IgG1, IgG2a and total IgG antibodies, native protein cross-reactive antibodies and cytokine production. Side effects were evaluated based on clinical and behavioural abnormalities, and (histo)pathological changes. Although marked differences in isotype profile and height of titre are observed among the different adjuvants used, we found that FA, Montanide ISA50 and Specol worked equally well in the s.c. and i.p. route, TiterMax functioned only when given i.p. and RIBI also did not perform up to par. The number of cytokine (interferon-gamma and interleukin-4) producing spleen cells was significantly higher after injection of RIBI compared with other adjuvants. Injection of FA or TiterMax resulted in severe pathological changes while after RIBI injection minimal changes were observed. In conclusion, high peptide specific antibody levels with limited side effects can be obtained by s.c. injection of peptide combined with Montanide ISA50 or Specol as alternatives to FA.

Former poison gas workers and cancer: incidence and inhibition of tumor formation by treatment with biological response modifier N-CWS

Mustard gas is known to have mutagenic and carcinogenic effects on animal and human cells. In this report, 1,632 male Japanese who worked in poison gas factories at some time between the years 1927 and 1945 were studied to determine comparative risk for development of cancer, the reference population being data on Japanese males overall. The standardized mortality ratio (SMR) for lung cancer in workers directly and indirectly involved in the production of mustard gas was significantly elevated. In addition, SMR for lung cancer in worker who had worked for more than 5 years was also significantly elevated. Thus, poison gas workers who had engaged in the production of mustard gas or related work for more than 5 years are a high-risk group for lung cancer. Under the cancer preventive program, Nocardia rubra cell-wall skeleton (N-CWS) was administered to 146 former poison gas workers. During a 4.5 year observation period, development of cancers was found in 7 treated workers and 17 untreated controls. After elimination of the influence of smoking level, a significant suppression of development of cancers was noted in the N-CWS-treated workers as compared to the untreated controls. Although the molecular mechanisms of carcinogenesis in former poison gas workers remains unclear, our study proposes the possible effect of biological response modifiers in the prevention of cancer development in high-risk human subjects.

Evaluation of several adjuvants as alternatives to the use of Freund's adjuvant in rabbits

In three experiments we evaluated several types of adjuvants as an alternative to Freund's adjuvant (FA). In the first experiment three adjuvant preparations (a water-in-oil emulsion (Specol), a combination preparation of monophosphoryl lipid A + trehalose dimycolate + cell wall skeleton and a non-ionic block polymer surfactant (TiterMax)) were evaluated. The adjuvants were combined with three different types of weak immunogenic antigens (synthetic peptide, glycolipid and particulate antigen) and administered following the intramuscular and subcutaneous route. The evaluation was based on clinical, pathological and immunological parameters. The animals did not appear to be severely or chronically impaired by the experiment. After injection of the RIBI adjuvant, side effects of the same severity as with FA were induced, while low antibody titers were produced. TiterMax caused few side effects, while antibody responses were very low. In comparing Specol and FA, Specol had far fewer adverse effects than FA. However, Specol had immunostimulating properties of the same level as FA. In the second experiment, the effect of injected volume of FA on side effects and antibody titer was studied. Immunization of rabbits with a total of 0.5 ml FA at different sites does not seem to increase the immune response when compared with the immune response seen after injection of 0.5 ml FA at one site. However side effects were seen in all the animals. In the third experiment, the side effects following intradermal (i.d.) injection of the adjuvants were studied. After i.d. injection of FA or RIBI, undesirable effects were found. No side effects occurred after i.d. injection of Specol or TiterMax. From the studies it is concluded that Specol is an alternative to FA for hyperactivation of the immune response in rabbits.

Clinical usefulness of continuous administration of Nocardia rubra cell wall skeleton (N-CWS) in diffuse panbronchiolitis (DPB)

Eight patients with diffuse panbronchiolitis (DPB) who had repeated intractable airway infections were continuously treated with Nocardia rubra cell wall skeleton (N-CWS), a biological response modifier. As a result, subjective symptoms were reduced in 6 patients. Antibiotics therapy could be discontinued completely in two patients and the dose of antibiotics could be reduced considerably in two other patients. No adverse reactions in relation to N-CWS were observed. These results suggest that N-CWS is effective in treating erythromycin-resistant DPB.