Vaccination is a powerful method against diseases. According to the World Health Organization (WHO), around 2.5 million children's lives are saved each year due to the availability of vaccines against a variety of antigens. Vaccines are not only used in a preventive manner but also therapeutically as well e.g. in oncology or in Alzheimer's disease. The immune system works by first capturing antigens, subsequently amplifying a complex network of specialized cells that are adept at clearing pathogens, and ultimately creating an immunological memory of that agent in the event of future exposure. Antigen presenting cells, (APCs), such as B cells, macrophages and dendritic cells (DCs), take up antigens and process these and present fragments of these antigens on the surface through MHC class I and II pathways for recognition by the T-cell receptors present on the T-cells. DCs are unique in their ability to activate naive T cells. Dendritic Cells (DC) play therefore a central role in the vaccination process. This process of antigen presentation typically takes place in the regional lymph node after chemokine dependent migration of the antigen loaded DC. Also, antigen presenting cells (APCs) perceive danger signals from cells and offer co-stimulatory signals through co-stimulatory molecules present on their surface for recognition by receptors on recirculating T-cells to initiate an immune response in the lymph node. Upon encountering the danger signals, immature DCs change to a mature stage where they present the antigen on their surface. This step is usually concurrent with the migration of DCs from peripheral tissue to the lymph node for T-cell activation. It is believed that soon after antigen presentation, the DCs undergo apoptosis in the lymph nodes.
In addition, to antigens, vaccine composition often comprise adjuvants. Adjuvants are agents that enhance or boost the immune response of a recipient to a administered antigen. For instance, subunit vaccines, require the addition of adjuvants for a proper immune response.
Nanoparticles and microparticles have been used in vaccine compositions. Biodegradable nanoparticles comprising of poly (D,L-lactic-co-glycolic-acid) (PLGA) have been used to encapsulate antigens or adjuvants. Also polystyrene beads with ovalbumin (OVA) have been tested.
It was disclosed that Micelles (Peptide Cross-linked micelles-PCMs) PCMs that are composed of block copolymers and encapsulate immuno stimulatory DNA in the core and bind peptide antigens through disulphide linkages. In the presence of a high concentration of glutathione they deliver antigenic peptides and immuno stimulatory DNA to APCs (Hao et al, Int J Nanomedicine. 2006; 1:97-103, Hirosue et al, Vaccine 28 (2010) 7897-7906). However, disulphide bridges do not allow for controlled release.
However, the use of nanoparticles in vaccination still has several bottlenecks. It is e.g. required that sufficient antigens should be presented to dendritic cells (DC) in a way that leads to a sufficient immune activation. Thereby preferably avoiding tolerance or auto immunity. Often, several vaccinations are needed to require long immunisation.
Furthermore, for each purpose, the vaccine composition needs optimisation. It requires, the appropriate selection of immunisation methods and/or adjuvants. It depends very much on the type of use, preventive, or therapeutic. Moreover, one tries to avoid unwanted side effects such as autoimmune disease, and tolerance.
It is also seen that the majority of nanoparticles are taken up by macrophages upon administration while the target is preferably DCs. Another disadvantage of the current nano- and microparticle is that they comprise physically encapsulated antigen and/or adjuvant, i.e. the antigen and/or adjuvant is not covalently entrapped by the nano- or microparticle. This means that there is no or minimal control over the release profile while this is crucial for best immune system presentation/activation. It is often seen that there is a burst release of the antigen and/or adjuvant when the particles are administered because of the inherent biological instability of the nano- or microparticles of the prior art. The release of the antigen and/or adjuvant takes place at the site of administration instead of the site/cells where it is most useful to present the adjuvant and antigen. Furthermore, the nanoparticles in the prior art themselves are all physical assemblies, meaning the forces holding the particle together are physical forces and not covalent linked, and thus often these particle are unstable. In addition, antigens and/or adjuvants are mostly physically adsorbed to the nanoparticle surface, which is much less stable than covalent bonding and does not allow for a controlled release or to a much lower extent. Moreover, although the nanoparticles themselves are described as single molecular entities, the structural integrity of these nanoparticles is largely unknown, because of the method of production and the physical assembly and encapsulation. Often, these nanoparticles to a large extent disrupt after administration to the animals. The instability of the nanoparticle, may result in that not all antigen is associated with the carrier. For example, it was shown that 25% of the OVA was not associated with the liposomes. Trimethylchitosan (TMC) nanoparticles and showed a burst release of approx. 20% OVA within the first day, followed by no further detectable release of OVA over three weeks. Similarly, PLGA microspheres produced an immediate OVA burst release, which amounted to 32% and 10% of the total dose for the microspheres loaded with OVA alone or with both OVA and CpG, respectively. No further protein release was detectable during the subsequent three weeks. (Mohanan et al, J. Control Rel (2010) vol 147:3; 342-349).
Another disadvantage is that the production of the nanoparticle may affect the antigen structure, e.g. see the advantages and disadvantages of nanoparticle preparation methods (Kunda et al, Pharm Res (2013) 30:325-341).
It appears that the uptake of nanoparticle in target cells is largely size and composition dependent, thus requiring full control of the size and composition. For many nanoparticles, and methods of production in the prior art however it is not possible to control the size and/or composition. Indeed, most of the particles of the prior art show a large distribution in size, thereby rendering a vaccine composition based on the particles heterogeneous, or requiring further purification. Furthermore for vaccination purposes there has to be a tight control over the encapsulation of antigen and/or adjuvant, and/or attachment of the targeting agent to ensure batch to batch reproducibility. Most of the nanoparticles in the prior art do not enable such a tight control, and are therefore not suitable for vaccination purposes and to generate a robust therapeutic response.
Often, for the nanoparticles of the prior art, the immune response is not long enough, e.g. because of the burst release, and thus additional boosting schedules are required for sufficient immune response.
WO2010/138193 is directed to compositions of synthetic nanocarriers that may target sites of action in cells, such as antigen presenting cells and comprise immunomodulatory agents that dissociate from the synthetic nanocarriers in a pH sensitive manner. The synthetic nanocarriers of WO2010/138193 are preferentially taken up by APCs. Upon being taken up by the APC, the synthetic nanocarriers are presumed to be endocytosed into an endosomal/lysosomal compartment where the pH becomes more acidic, as opposed to the neutral pH outside the cells. Under these conditions, the immunomodulatory agent exhibits a pH sensitive dissociation from the synthetic nanocarrier and is released from the synthetic nanocarrier. The immunomodulatory agent is then free to interact with receptors associated with the endosome/lysosome and stimulate a desired immune response. However WO2010/138193 does not discloses cross-linking of the polymers when the immunomodulatory agent is present. There is no disclosure of a system wherein the immunomodulatory agent is covalently entrapped into the nanoparticle. In WO2010/138193 particles are made by first conjugating the immunomodulatory agent to the polymer and then make nanoparticles of the immunomodulatory agent-polymer complex. The system of WO2010/138193 thus requires different routes for conjugation for each different immunomodulatory agent.
US2009/011993 is directed to particles that deliver active agents such as vaccines, immune modulatory agents and/or drugs that target antigen presenting cells. US2009/011993 discloses a new type of hydrophobic polymers comprising ketal groups in the polymer backbone wherein the ketal groups are arranged in a way such that both oxygen atoms are located in the polymer backbone. US2009/011993 discloses the use of an external crosslinking agent to cross-link the polymers to the immune modulatory agents, and does not disclose a crosslinking step of the polymers in the presence of immune modulatory agents.
Unfortunately there seems to be no universal formulation that can be universally be applied to various (subunit) vaccines. For most systems of the prior art, the particles and conjugation needs an optimisation for each different immunomodulatory agent. This requires extensive research for each new particle with a another immunomodulatory agent, and creates differences between the different immunomodulatory agents. The optimum formulation preferably depends on the type of response required for protective immunity and the intended route of administration. Various formulation aspects, such as particles size, choice of adjuvant, and co-localization of antigen and adjuvant, are preferably adjusted based on the selected administration route. The nanoparticles described in the prior art may be suitable for one particular antigen and/or adjuvant and for one particular route of administration, but are often unsuitable for another antigen/adjuvant and/or other route of administration. Thus for different vaccination routes, each time a different nanoparticle has to be developed.
WO 2010/033022 and WO2013/002636 disclose a controlled release system comprising drugs such as dexamethasone and paclitaxel, however they do not disclose that antigens and/or adjuvants may be entrapped in the polymeric matrix particles.
WO2012/039602 discloses biodegradable linker molecules that may be used in a covalent polymer matrix particle such as disclosed in WO 2010/033022 and WO2013/002636. WO2012/039602 does not disclose antigens or adjuvants in such a system.
It is therefore an object of the present invention to provide a vaccination composition. It is furthermore an object of the present invention to provide a vaccination composition that is easily adjustable for different administration routes. In addition, the vaccination composition preferably provides a system with covalent bonding of an antigen and/or adjuvant thereby ensuring full control over the local and time-spatial exposure to adjuvant or antigen. Another object of the invention is to provide a vaccination composition comprising nano- and/or microparticles. Furthermore, another object of the present invention is to provide a vaccine composition wherein the controlled release particles have a narrow size distribution. Yet another object of the invention is to provide a vaccination composition that may accommodate different antigens and/or adjuvants, e.g. both hydrophilic and hydrophobic compounds and over a large size range. Moreover, another object of the invention is to provide a vaccination composition wherein the release of the adjuvant and/or antigen can be controlled. Another object of the invention is to provide a vaccination composition wherein each entrapped adjuvant and/or antigen has its own unique release profile. Even another object of the present invention is to provide a vaccination composition that comprises targeting agents covalently attached to the particle, e.g. to its surface. The targeting agent may direct the particle of the present invention to the cells or site of interest, such as APCs. Moreover, another object of the invention is to provide a vaccination system wherein the antigen and/or adjuvant may be encapsulated but may also be present on the surface of a particle or both. Yet another object of the invention is to provide method for producing the vaccination composition that is safe and/or non-destructive for the antigen and/or adjuvant.
The present invention provides a vaccination composition that meets one or more of the above mentioned objects.