Pre-clinical safety evaluation of heat shock protein 65–MUC1 peptide fusion protein

Novel molecules as the emerging trends in cancer treatment: an update

As per World Health Organization cancer remains as a leading killer disease causing nearly 10 million deaths in 2020. Since the burden of cancer increases worldwide, warranting an urgent search for anti-cancer compounds from natural sources. Secondary metabolites from plants, marine organisms exhibit a novel chemical and structural diversity holding a great promise as therapeutics in cancer treatment. These natural metabolites target only the cancer cells and the normal healthy cells are left unharmed. In the emerging trends of cancer treatment, the natural bioactive compounds have long become a part of cancer chemotherapy. In this review, we have tried to compile about eight bioactive compounds from plant origin viz. combretastatin, ginsenoside, lycopene, quercetin, resveratrol, silymarin, sulforaphane and withaferin A, four marine-derived compounds viz. bryostatins, dolastatins, eribulin, plitidepsin and three microorganisms viz. Clostridium, Mycobacterium bovis and Streptococcus pyogenes with their well-established anticancer potential, mechanism of action and clinical establishments are presented.

Preclinical evaluation of recombinant HFMD vaccine based on enterovirus 71 (EV71) virus-like particles (VLP): Immunogenicity, efficacy and toxicology

Enterovirus 71 (EV71) is one of the major causative agents for hand, foot and mouth disease (HFMD) in children. Currently, three inactivated EV71 vaccines have been approved by Chinese government. We previously demonstrated that recombinant EV71 virus-like particles (VLP) produced in Pichia pastoris can be produced at a high yield with a simple manufacturing process, and the candidate vaccine elicited protective humoral immune responses in mice. In present study, the nonclinical immunogenicity, efficacy and toxicity of the EV71 vaccine was comprehensively evaluated in rodents and non-human primates. The immunogenicity assessment showed that EV71 VLPs vaccine elicited high and persistent neutralizing antibody responses, which could be comparable with a licensed inactivated vaccine in animals. The immune sera of vaccinated mice also exhibited cross-neutralization activities to the heterologous subtypes of EV71. Both passive and maternal antigen specific antibodies protected the neonatal mice against the lethal EV71 challenge. Furthermore, nonclinical safety assessment of EV71 VLP vaccine showed no signs of systemic toxicity in animals. Therefore, the excellent immunogenicity, efficacy and toxicology data supported further evaluation of the VLP-based EV71 vaccine in humans.

Mycobacteria-Based Vaccines as Immunotherapy for Non-urological Cancers

The arsenal against different types of cancers has increased impressively in the last decade. The detailed knowledge of the tumor microenvironment enables it to be manipulated in order to help the immune system fight against tumor cells by using specific checkpoint inhibitors, cell-based treatments, targeted antibodies, and immune stimulants. In fact, it is widely known that the first immunotherapeutic tools as immune stimulants for cancer treatment were bacteria and still are; specifically, the use of Mycobacterium bovis bacillus Calmette-Guérin (BCG) continues to be the treatment of choice for preventing cancer recurrence and progression in non-invasive bladder cancer. BCG and also other mycobacteria or their components are currently under study for the immunotherapeutic treatment of different malignancies. This review focuses on the preclinical and clinical assays using mycobacteria to treat non-urological cancers, providing a wide knowledge of the beneficial applications of these microorganisms to manipulate the tumor microenvironment aiming at tumor clearance.

Preclinical safety evaluation of recombinant adeno-associated virus 2 vector encoding human tumor necrosis factor receptor-immunoglobulin Fc fusion gene

Recombinant adeno-associated virus (rAAV) 2 vector gene therapy offers promise for the healing of Rheumatoid arthritis. To support the clinical development of the candidate gene therapeutic product in China, a comprehensive preclinical safety assessment of rAAV2 encoding human TNF receptor-immunoglobulin Fc fusion gene (rAAV2/human TNFR:Fc), were conducted in 3 species of experimental animals. No abnormal findings were observed in mice following single intravenous administration with test article. Compared with the control group, no differences in mean body weight, food consumption in rats and monkeys following the repeated intraarticular administration with rAAV2/human TNFR:Fc. There were also no significant adverse effects due to treatment noted by clinical chemistry, hematology and pathology assessments. After intraarticular administration with rAAV2/human TNFR:Fc, the vector DNA initially distributed to spleen, lymph nodes, and joint synovium. The vector DNA cleared rapidly as it could be detected mainly at the site of injection by 91 d post-administration (182 d for monkey). Taken together, localized delivery of rAAV2/human TNFR:Fc showed no significant toxicity in mice, rats, and monkeys, which support the planned clinical evaluation of this product.

Pre-clinical toxicity and immunogenicity evaluation of a MUC1-MBP/BCG anti-tumor vaccine

Mucin 1 (MUC1), as an oncogene, plays a key role in the progression and tumorigenesis of many human adenocarcinomas and is an attractive target in tumor immunotherapy. Our previous study showed that the MUC1-MBP/BCG anti-tumor vaccine induced a MUC1-specific Th1-dominant immune response, simulated MUC1-specific cytotoxic T lymphocyte killing activity, and could significantly inhibit MUC1-expression B16 cells' growth in mice. To help move the vaccine into a Phase I clinical trial, in the current study, a pre-clinical toxicity and immunogenicity evaluation of the vaccine was conducted. The evaluation was comprised of a single-dose acute toxicity study in mice, repeat-dose chronic toxicity and immunogenicity studies in rats, and pilot toxicity and immunogenicity studies in cynomolgus monkeys. The results showed that treatment with the MUC1-MBP/BCG anti-tumor vaccine did not cause any organ toxicity, except for arthritis or local nodules induced by BCG in several rats. Furthermore, the vaccine significantly increased the levels of IFN-γ in rats, indicating that Th1 cells were activated. In addition, the results showed that the MUC1-MBP/BCG anti-tumor vaccine induced a MUC1-specific IgG antibody response both in rats and cynomolgus monkeys. Collectively, these data are beneficial to move the MUC1-MBP/BCG anti-tumor vaccine into a Phase I clinical trial.

Dendritic cells primed with protein-protein fusion adjuvant

To develop efficient T cell priming cancer vaccines, various recombinant fusion proteins have been developed by fusing a tumor antigen with a protein capable of stimulating or targeting dendritic cells (DC), the most important antigen-presenting cells for inducing CD8(+) cytotoxic T lymphocytes (CTL) which can efficiently kill tumor cells expressing the tumor antigen. The DC-stimulating or DC-targeting proteins, including granulocyte/macrophage colony-stimulating factor (GM-CSF), anti-DEC-205 monoclonal antibodies, flagellin, and heat shock proteins (HSP), function as promising intermolecular adjuvants. Herein, we describe in vitro assays on human DC pulsed with HSP fusion proteins, which might be useful in preclinical studies for the screening and assessment of candidate cancer vaccines.

A safety study of inactivated Enterovirus 71 vaccine

Enterovirus 71 (EV71) is one of the major causative agents for hand, foot and mouth disease (HFMD) in childhood. Nowadays, HFMD or EV71 infections have already become an important public health issue throughout the world. Vaccination may be the most effective measure to control the transmission of the virus. Therefore, to pave EV71 vaccine into human clinical trial, in the present study a comprehensive preclinical safety assessment of inactivated EV71 vaccine including single- and repeat-dose toxicity studies were conducted in rats and cynomolgus monkeys. No abnormal findings were observed in rats following single intramuscular administration with EV71 vaccine (640 U). The results also showed no obvious systemic toxicities from four repetitive intramuscular injections, with a 14-d interval, of two dosages of EV71 vaccine in the two animal species. Antinuclear antibody response was not detected after the repeated administrations. Histopathological examination demonstrated the minimal to severe inflammatory changes in muscle tissues of the injection sites in EV71 vaccine-injected animals and most of findings have been improved over time. Furthermore, test article could induce highly EV71-specfic neutralizing antibody response in both animal species. Taken together, these data suggested a favorable safety profile for inactivated EV71 vaccine and supported this product to enter human phase I clinical trial.

MUC1-based recombinant Bacillus Calmette-Guerin vaccines as candidates for breast cancer immunotherapy

IMPORTANCE OF THE FIELD

The challenge in breast cancer vaccine development is to find the best combination of antigen, adjuvant and delivery system to produce a strong and long-lasting immune response. Mucin 1 (MUC1) is a potential candidate target for breast cancer immunotherapy. Bacillus Calmette-Guerin (BCG) is used widely in human vaccines. Furthermore, it can potentially offer unique advantages for developing a safe and effective multi-vaccine vehicle. Due to these properties, the development of MUC1 based recombinant BCG (rBCG) vaccines for breast cancer immunotherapy has gained great momentum in recent years.

AREAS COVERED IN THIS REVIEW

Our aim is to discuss the recent progress in MUC1-based breast cancer immunotherapy and to highlight the advantages of MUC1-based rBCG vaccines as the new breast cancer vaccines.

WHAT THE READER WILL GAIN

Several promising MUC1-based rBCG vaccines have been shown to induce MUC1-specific antitumor immune responses in pre-clinical studies. This review updates and evaluates this very important and rapidly developing field, and provides a critical perspective and information source for its potential clinical applications.

TAKE HOME MESSAGE

MUC1-based rBCG vaccines have been shown to elicit an effective anti-tumor immune response in vivo demonstrating its potential utility in breast cancer treatment.

Purification of clinical-grade recombinant HSP65-MUCI fusion protein

HSP65-MUCI is a fusion protein between BCG (Bacille Calmette-Guerin)-derived HSP65 (heat-shock protein 65) and human MUCI (mucin I) VNTR (variable number of tandem repeats)-domain peptides that has shown antitumour efficacy. China's Food and Drug Administration has recently approved a Phase I clinical trial using HSP65-MUCI for the treatment of MUCI-positive breast cancer. In order to produce sufficient quantities of clinical-grade HSP65-MUCI, we established a pilot-scale purification scheme comprising two steps of column chromatography: HIC (hydrophobic-interaction chromatography) and IEX (ion-exchange chromatography). The pH values of the buffers used in homogenization and HIC were adjusted to pH 9.0 to maintain protein stability and prevent protein degradation. Using this manufacturing process, we obtained clinical-grade HSP65-MUCI with a yield of 400 mg per 70 g of wet cell pellet and >96% purity.

Immunization with two recombinant Bacillus Calmette-Guérin vaccines that combine the expression of multiple tandem repeats of mucin-1 and colony stimulating-factor suppress breast tumor growth in mice

PURPOSE

Mucin-1 (MUC1) is a breast tumor-associated antigen. However, clinical trials with MUC1 showed that, with respect to its expression levels, MUC1 is a relatively poor immunogen in human beings. Evidence showed that MUC1-specific immunodominant B and T cell epitopes are derived from the variable-number tandem repeat (VNTR) region. Therefore, immunotherapy that targets multiple VNTRs may induce anti-MUC1 immune responses. GM-CSF has been shown to increase the percentage and activity of antigen-presenting cells. In this study, we constructed two recombinant Bacillus Calmette-Guérin (BCG) vaccines that combine the expression of multiple tandem repeats of MUC1 and CSF. The effect of two novel breast cancer vaccines (rBCG-MVNTR4-CSF and rBCG-MVNTR8-CSF) on the growth of breast tumor on hu-PBL-SCID mice was evaluated.

METHODS

We coupled VNTRs (4 and 8) of MUC1 with GM-CSF (MVNTR4-CSF and MVNTR8-CSF). The MVNTR4-CSF and MVNTR8-CSF were inserted into the pDE22 plasmid and transformed into competent BCG by electroporation. The effect of both BCG vaccines on the growth of breast tumor on hu-PBL-SCID mice was evaluated.

RESULTS

The growth of MUC1-positive breast tumors from hu-PBL-SCID mice immunized with two vaccines was significantly inhibited.

CONCLUSIONS

rBCG-MVNTR4-CSF and rBCG-MVNTR8-CSF vaccines may be good candidates for breast tumor immunotherapy.