21.1 The specification
628 The container patent is entitled "Novel Formulations which Stabilize and Inhibit Precipitation of Immunogenic Compositions". The invention is said generally to relate to the fields of immunology, bacteriology, vaccine formulation, protein stability and process development. More particularly, the invention is said to relate to "novel formulations which inhibit precipitation of immunogenic compositions".
629 The Background of the Invention provides an important basis for understanding the invention that is described. It refers to the general acceptance in the bio-pharmaceutical arts that improving the stability of an immunogenic composition is a necessary and highly desirable goal. It gives two examples of an "immunogenic composition" being a protein immunogen and a polysaccharide-protein conjugate. The Background goes on to say (emphasis added):
...an immunogenic composition must appear fresh, elegant and professional when administered to a patient. Any changes in stability and/or physical appearance of the immunogenic composition, such as color change, clouding or haziness, may cause a patient or consumer to lose confidence in the product. Furthermore, because many immunogenic formulations are dispensed in multiple-dose containers, uniformity of dose content of the active ingredient (e.g., a polysaccharide-protein conjugate) over time must be assured (e.g., a cloudy solution can lead to a non-uniform dosage pattern). Additionally, the immunogenic composition must be active throughout its "expected" shelf life, wherein any breakdown of the immunogenic composition to an inactive or otherwise undesired form (e.g., an aggregate) lowers the total concentration of the product.
630 The Background refers to several reports in the literature suggesting that the stability of a particular immunogenic composition is at least in part dependent upon the specific protein or carrier protein. Reference is made to three publications, being Bolgiano, Ho, and an article by Ho et al entitled "Physico-Chemical and immunological examination of the termal stability of tetanus toxoid conjugate vaccines" published in 2002 in Vaccine (Volume 20) (Ho 2002). These, and about 16 other publications, are identified by their full titles and publication details at the conclusion of the specification. They are all said to be incorporated by reference into the specification. The specification later states that the reference to any publication or information in a publication, or to any matter which is said to be known, is not to be taken as an acknowledgement or admission that such material forms part of the common general knowledge.
631 The Background continues by saying that by way of example, stability analysis in Ho 2002 of meningococcal C (MenC) polysaccharides and Haemophilus influenzae type b polysaccharides, conjugated either to a tetanus toxoid or a CRM197 carrier protein, revealed different stability profiles dependent on the carrier protein. In Ho 2001, MenC-CRM197 conjugates from two different manufacturers were analysed where the MenC-CRM197 conjugates differed in their conjugation chemistry and length of conjugate polysaccharide (both having the same carrier protein, CRM197). The Background goes on (page 2 lines 7 - 11):
Data from this study further indicated that factors such as conjugation chemistry (e.g. reductive amination either directly or via a chemical spacer group), number of conjugation sites, polysaccharide chain length, pH, storage buffer, storage temperature(s) and freeze/thaw cycles also influence the stability of an immunogenic composition.
632 The Background then says that when developing a formulation for an immunogenic composition, many factors must be considered to ensure that it is safe, stable, robust and cost effective. These include (page 2 lines 14 - 23):
...chemical stability of the immunogenic composition (e.g. hydrolysis of saccharides, de-polymerization of polysaccharides, proteolysis or fragmentation of proteins), physical/thermal stability of the immunogenic composition (e.g. aggregation, precipitation, adsorption), compatibility of the immunogenic composition with the container/closure system, interactions between immunogenic composition and inactive ingredients (e.g. buffers, salts, excipients, cryoprotectants), the manufacturing process, the dosage form (e.g. lyophilized, liquid), the environmental conditions encountered during shipping, storage and handling (e.g. temperature, humidity, shear forces), and the length of time between manufacture and usage.
633 The Background then refers to the problem caused by silicone oil (page 2 lines 24 - 33):
It has been suggested in the art, that silicone oil, which induces protein secondary and tertiary conformational changes, might be responsible for the aggregation/precipitation seen in certain protein pharmaceutical preparations (Jones et al., 2005). For example, several reports in the 1980s implicated the release of silicone oil from disposable plastic syringes as the causative agent in the aggregation of human insulin [six references are then given]. Chantelau et al. (1986) observed that after three or more withdrawals from a ten-dose preparation of insulin (using a siliconized disposable syringe), the vial would begin clouding due [to] silicone oil contamination, thereby resulting in aggregation and deactivation of the insulin (Chantelau et al., 1986). Paradoxically, silicone oil is a necessary component of plastic syringes, as it serves to lubricate the rubber plunger and facilitate transfer of the plunger down the syringe barrel (i.e., silicone oil improves the syringeability of the formulation).
634 The specification later notes that the words "precipitation", "aggregation", "clouding" and "particulate formulation" may be used interchangeably and are meant to refer to any physical interaction or chemical reaction which results in the "aggregation" of a polysaccharide-protein conjugate or a protein (or polypeptide) immunogen.
635 The Background continues by noting that the use of silicone oil is not limited to syringes, as it is used as a coating for glass vials to minimise adsorption, as a lubricant to prevent conglomeration of rubber stoppers during filing procedures, as a lubricant critical to the processability/machinability of glass and elastomeric closures and as a lubricant to ease needle penetration of vial rubber stoppers. It notes that the siliconisation of such containers is not well controlled or standardised and that there is a high degree of variability of the silicone oil content from one lot to another.
636 The Background concludes:
There is therefore an ongoing need in the art for formulations which enhance stability and inhibit precipitation of immunogenic compositions.
637 It is apparent that the focus of the Background is upon the formulation of immunogenic compositions to ensure that they are stable. There are said to be many considerations relevant to producing a suitable formulation, but a particular problem is identified as arising from the use of silicone oil which might be responsible for aggregation. The literature cited is said to indicate that cloudiness results.
638 The specification then provides a Summary of the Invention which extends from page 3 to page 12. It begins (page 3 lines 12 - 17):
The present invention broadly relates to novel formulations which stabilize and inhibit precipitation of immunogenic compositions. More specifically in certain embodiments, the present invention is directed to novel formulations which inhibit precipitation of immunogenic compositions comprised in container means. In one specific embodiment, the invention is directed to novel formulations which stabilize immunogenic compositions against silicone oil interactions, shear forces, shipping agitation, and the like.
639 There follows a consistory statement for claim 1:
Thus, in certain embodiments, the present invention is directed to a siliconized container means filled with a formulation comprising (i) a pH buffered saline solution, wherein the buffer has a pKa of about 3.5 to about 7.5, (ii) an aluminium salt and (iii) one or more polysaccharide-protein conjugates wherein the polysaccharide-protein conjugate comprises one or more pneumococcal polysaccharides.
640 In this form, the invention is essentially for any formulation of one or more pneumococcal polysaccharide-protein conjugates in a siliconised container that includes pH buffered saline in the range specified and an aluminium salt. The claim is not limited to any particular protein carrier. As the expert evidence reveals, the pH buffered saline solution is to improve the stability of the formulation. The expert evidence also indicates that the pKa range of 3.5 to 7.5 is broad. As a rule of thumb, a buffer is effective within one pH unit of its pKa value. Applying the rule of thumb, Professor Petrovsky considers that the range would include pH of 2.5 to 8.5. The aluminium salt is an adjuvant that is said in the specification to enhance the immune response of the vaccine antigen.
641 The Summary of the Invention is also (emphasis added):
...directed to formulations which stabilize a polysaccharide-protein conjugate, the formulation comprising (i) a pH buffered saline solution, wherein the buffer has a pKa of about 3.5 to about 7.5, (ii) a surfactant and (iii) one or more polysaccharide-protein conjugates.
(page 3 lines 22 - 26)
642 A surfactant is a class of detergent that acts as a surface-active agent, being a compound that lowers the surface tension between either two liquids, a liquid and a solid, or a gas and a liquid. The specification later says that a surfactant is generally defined as a molecule or compound comprising a hydrophilic group or moiety and a liphoilic (hydrophobic) group or moiety, and/or a molecule, substance or compound that lowers or reduces surface tension of a solution. It is said that any surfactant or any combination of surfactants which stabilises and inhibits aggregation of an immunogenic composition may be used in the invention. It further says (page 17 lines 33 - 36):
A person of skill in the art may readily determine a suitable surfactant or surfactant combination by measuring the surface tension of a particular immunogenic composition formulation in the presence and absence of the surfactant(s).
643 Numerous other embodiments are described in the Summary of the Invention.
644 The specification then provides a Brief Description of the Figures. Figure 2 is described as showing the total antigenicity loss of the 13-valent pneumococcal conjugate vaccine (with the 13 chosen serotypes) formulated with AIPO4 (0.25mg/ml) and filled in a BD Hypak syringe after two hours, eight hours and 24 hours of agitation at 500 rpm and 2 - 8 degrees Celsius.
645 The Detailed Description of the Invention commences on page 13 and includes sections entitled Surfactants, Container Means, Adjuvants and Pharmaceutical Carriers/Excipients, Immunogens, and Examples.
646 In the introductory part, the Detailed Description provides the following broad characterisation of the invention (page 13 lines 5 - 14):
The present invention addresses an ongoing need in the art to improve the stability of immunogenic compositions such as polysaccharide-protein conjugates and protein immunogens. Thus the present invention broadly relates to novel surfactant formulations and/or novel aluminium salt formulations which stabilize and inhibit precipitation of immunogenic compositions. More particularly, the invention described hereinafter, addresses a need in the art for formulations which stabilize and inhibit particulate formation (e.g., aggregation, precipitation) of immunogenic compositions which are processed, developed, formulated, manufactured and/or stored in container means such as fermenters, bioreactors, vials, flasks, bags, syringes, rubber stoppers, tubing and the like.
647 The specification then repeats what is set out in the Background concerning the various factors that influence the stability of immunogenic compositions. It then says (page 13 lines 24 - 26):
The stability of an immunogenic composition of the invention is readily determined using standard techniques, which are well known and routine to those of skill in the art.
648 Further down the same page it provides (page 13 lines 32 - 35) (emphasis added):
As set forth in detail herein, the present invention relates to the unexpected and surprising results that formulating an immunogenic composition with a surfactant such as Tween 80 significantly enhances the stability and inhibits precipitation of an immunogenic composition.
649 The specification then says that for example, it was observed in example 1 (the text reads "example 2" but is in error) that a 13-valent pneumococcal conjugate formulated in buffered saline and filled in a single dose syringe would begin precipitating out of solution within 10 minutes at 2 - 8 degrees Celsius upon gentle agitation. The Detailed Description says (page 14 lines 5 - 14) (emphasis added):
However it was surprisingly observed that the 13vPnC, formulated in buffered saline and 0.001% Tween 80, filled in a single dose syringe and gently agitated at 2-8 degrees°C, was stable for twenty-five days with no visible signs of precipitation (data not shown). Thus, this data demonstrated that the addition of a surfactant (e.g., Tween 80) to an immunogenic composition formulation enhances the stability of the immunogenic composition.
A second stability study of the 13vPnC further confirmed that the addition of a surfactant to the formulation significantly enhanced the stability of the 13vPnC...
650 The specification then says that in other experiments it was demonstrated that the stability of an immunogenic streptococcal C5a peptidase composition was greatly enhanced when formulated with a surfactant such as Tween 80. It also notes that a 13-valent pneumococcal conjugate immunogenic composition of the invention may also be formulated with or without an adjuvant, such as aluminium phosphate. Example 4 is said to be experiments formulated with a buffer, salt and AIPO4, without the addition of a surfactant. The specification observes that in an experiment within example 4, where immunogenic compositions were formulated with and without AIPO4 in identical syringes, it was observed that the 13-valent pneumococcal conjugate, formulated without the adjuvant, sustained greater antigenicity losses than with it, referring to Figures 6 and 7.
651 The specification then provides a further statement of the invention (page 15 lines 18 - 25):
Thus, the invention as set forth herein, is directed to novel formulations which stabilize and inhibit aggregation or precipitation of immunogenic compositions such as polysaccharide-protein conjugates (e.g., a 13vPnC) and protein immunogens (e.g., a streptococcal C5a peptidase...), against the various factors which influence the stability of immunogenic compositions (e.g., shear forces, shipping agitation, silicone oil interactions, adsorption, manufacturing processes, temperature, humidity, length of time between manufacture and usage, etc.).
652 Later the specification states that "in certain other embodiments, the invention is directed to a formulation which inhibits silicone oil induced precipitation of a polysaccharide-protein conjugate comprised in a siliconized container means". The specification goes on (page 16 lines 29 - 34):
The process of aggregation (e.g., protein aggregation) is well known (but not well understood) and described in the art, and is often influenced by numerous physicochemical stresses, including heat, pressure, pH, agitation, shear forces, freeze-thawing, dehydration, heavy metals, phenolic compounds, silicon oil, denaturant and the like.
653 Later, the Detailed Description supplies a definition of an adjuvant (page 19 lines 15 - 16):
An adjuvant is a substance that enhances the immune response when administered together with an immunogen or antigen.
654 The specification then makes reference to the carrier. It says (page 20 line 28 - page 21 line 2):
In certain embodiments, the immunogenic composition formulations comprise a pharmaceutically acceptable diluent, excipient or a pharmaceutically acceptable carrier...As used herein the language "pharmaceutically acceptable carrier" is intended to include any and all solvents, dispersion media, coatings, antibacterial and antifungal agents, isotonic and absorption delaying agents, and the like, compatible with administration to humans or other vertebrate hosts. The appropriate carrier is evident to those skilled in the art and will depend in large part upon the route of administration.
655 It later says (page 21 lines 18 - 24):
The immunogenic compositions of the present invention, are not limited by the selection of conventional, physiologically acceptable carriers, diluents and excipients such as solvents, buffers, adjuvants, or other ingredients useful in pharmaceutical preparations of the types described above. The preparation of these pharmaceutically acceptable compositions, from the above-described components, having appropriate pH isotonicity, stability and other conventional characteristics is within the skill of the art.
656 The specification then addresses immunogens, and defines the term "polysaccharides" to include any antigenic saccharide element commonly used in the immunologic and bacterial vaccine arts, including, but not limited to, a "saccharide", an "oligosaccharide", a "polysaccharide", a "glycoconjugate" and others. Polysaccharides are said to be "prepared by standard techniques known to those skilled in the art". The chemical activation of the polysaccharides and subsequent conjugation to the carrier protein (that is, a polysaccharide-protein conjugate) are said to be achieved "by conventional means".
657 The Detailed Description then moves to the examples, which are said to be presented for illustrative purposes only. I have summarised the effect of example 1 above. Example 2 concerns a formulation using the protein streptococcal C5a peptidase. Example 3 concerns the 13-valent pneumococcal conjugate considered in example 1, but is said to be focussed on the influence of the siliconised container means on stability. Example 4 repeats the experiments performed in example 3, with the exception that the antigenicity of the 13-valent pneumococcal conjugate antigen was tested using a methodology similar to that described in example 1. Example 5 describes an experimental analysis of a composition including the 2086 protein, which is not presently relevant.
658 It is apparent that the disclosure of the specification is to container means whereby stability issues arising in the formulation of immunogenic compositions for use as vaccines are addressed. One aspect of the invention, emphasised in the specification, is the use of surfactants to address aggregation that arises during the course of formulation, also described as precipitation arising from silicone oil induced aggregation.