Patent Description:
The present invention relates to methods for the quantitative determination of human serum albumin (HSA) monomer in virus-containing, in particular flavivirus, pharmaceutical compositions. The present invention also relates to the use of the methods in the quality control of virus-containing pharmaceutical compositions. In a further aspect the present invention also relate to the use of the inventive methods for monitoring the long-term stability of the HSA monomer in virus-containing pharmaceutical formulations.

Vaccines for protection against viral infections have been effectively used to reduce the incidence of human disease. One of the most successful technologies for viral vaccines is to immunize animals or humans with a weakened or attenuated virus strain (a "live attenuated virus"). The limited viral replication is sufficient to express the full repertoire of viral antigens and can generate potent and long-lasting immune responses to the virus. Thus, upon subsequent exposure to a pathogenic virus strain, the immunized individual is protected from the disease. These live attenuated viral vaccines are among the most successful vaccines used in public health.

Dengue disease is a mosquito-borne disease caused by infection with a dengue virus. Dengue virus infections can lead to debilitating and painful symptoms, including a sudden high fever, headaches, joint and muscle pain, nausea, vomiting and skin rashes. To date, four serotypes of dengue virus have been identified: dengue-l (DENV-l), dengue-<NUM> (DENV-<NUM>), dengue-<NUM> (DENV-<NUM>) and dengue-<NUM> (DENV-<NUM>). Dengue virus serotypes <NUM>-<NUM> can also cause dengue hemorrhagic fever (DHF) and dengue shock syndrome (DSS). In the most severe cases, DHF and DSS can be life threatening. Dengue viruses cause <NUM>-<NUM> million cases of debilitating dengue fever, <NUM>,<NUM> cases of DHF/DSS, and more than <NUM>,<NUM> deaths each year, a large portion of which are children. All four dengue virus serotypes are endemic throughout the tropical regions of the world and constitute the most significant mosquito-borne viral threat to humans there. Dengue viruses are transmitted to humans primarily by Aedes aegypti mosquitoes, but also by Aedes albopictus mosquitoes. Infection with one dengue virus serotype results in life-long protection from re-infection by that serotype, but does not prevent secondary infection by one of the other three dengue virus serotypes. In fact, previous infection with one dengue virus serotype may lead to an increased risk of severe disease (DHF/DSS) upon secondary infection with a different serotype.

Takeda has developed a tetravalent dengue vaccine candidate (TAK-<NUM>). This product is now approved as QDENGA® in Indonesia. The tetravalent dengue virus composition is a dengue virus composition comprising four different immunogenic components from the four different dengue serotypes DENV-<NUM>, DENV-<NUM>, DENV-<NUM> and DENV-<NUM>, comprising four different live, attenuated dengue viruses, each representing one dengue serotype, and which aims to stimulate immune responses to all four dengue serotypes.

Virus-containing pharmaceutical formulations frequently contain human serum albumin (HSA) as stabilizer of the active ingredients. Physical instability or denaturation of a protein often involves unfolding of the molecule. The unfolded protein is susceptible to further inactivation by aggregation. Aggregation usually leads to reduced bioactivity and immunogenic reactions, possibly because of increased molecular weight and unacceptable physical characteristics, such as the turbidity and opalescence, which gives the product undesirable properties. Like most large proteins, albumin also undergoes aggregation, the storage temperature being the main induction factor.

For quality control and reliable manufacture of vaccines including live attenuated viruses it is of utmost importance to determine the amount of HSA, in particular in its monomeric form, for example in the monovalent Bulk Drug Substance (BDS), and tetravalent vaccine drug product (DP). The determination of the amount of HSA can also be used as an in process control test (IPC) during manufacture.

In the prior art numerous techniques such as capillary electrophoresis, mass spectrometry, light scattering, size-exclusion chromatography and analytical ultracentrifugation are known for the determination of protein molecular weight of proteins. However, there is no validated method for the quantitative determination of HSA monomer in virus-containing pharmaceutical formulations, in particular for flavirus-containing vaccine formulations.

<CIT> describes in the examples a size-exclusion chromatography for the determination of HSA monomer in a composition comprising nanoparticles comprising albumin and paclitaxel. Neither the mobile phase composition nor the pH value are disclosed.

One technical problem underlying the present invention is therefore to provide such a validated method for the quantitative determination of HSA monomer, wherein the method is accurate, precise, specific and/or robust. The method shall be useful in routine methods for quality control of virus-containing complex pharmaceutical formulations.

The technical problems underlying the invention are solved by the provision of the subject-matter as defined in the claims.

According to a first aspect, the present invention provides a method for the quantitative determination of human serum albumin (HSA) monomer in a liquid composition comprising at least one virus and at least one pharmaceutically acceptable carrier other than HSA, wherein the method comprises the steps of:.

In a second aspect the present invention provides the use of the inventive method in the quality control of an in-process monovalent drug substance, a bulk monovalent drug substance and/or a final tetravalent drug product.

In a third aspect the present invention provides the use of the inventive method for monitoring the long-term stability of the HSA monomer in virus-containing pharmaceutical formulations.

In a fourth aspect the present invention provides a quality control for vaccines containing live, attenuated dengue virus comprising performing the method according to the present invention and at least one further method selected from the group consisting of identity assay, immunofocus assay, visual inspection, determination of reconstitution time or resuspendability of lyophilisates, sterility test, test for bacterial endotoxins, determination of host cell DNA, determination of pH, colorimetric determination of water, determination of osmolality, determination of the content of one or more excipient(s).

The inventors surprisingly found that the claimed method could be validated for pharmaceutical industry purposes, because it is accurate, precise, specific and robust. Since the viruses contained in the pharmaceutical formulations contain relevant amounts of different structural and non-structural proteins such as for dengue viruses e.g. the envelope protein, the pre-membrane protein, the capsid protein and, the non-structural proteins NSl, NS2A, NS2B, NS3, NS4A, NS4B, NS5 proteins, it would have been expected that these different proteins would provide relevant background complicating the analysis of HSA, in particular in its monomeric form.

This is further supported by the findings of <NPL> determining that size-exclusion HPLC does not resolve albumin from several other proteins in complex samples such as urine. The authors outlined that the albumin peak resolved by this technique, although predominantly composed of albumin, contains several coeluting globulins that would contribute to overestimation of albumin concentration by size-exclusion HPLC. The skilled person would have assumed to encounter similar problems for present complex sample comprising multiple proteins from the virus and potential fragments thereof.

The deliberate choice of the particular column material and mobile phase composition according to the present invention resulted in the provision of an excellent method. This is further improved in specific embodiments by the deliberate choice of a specific injection volume and specific flow rate which also contribute to the excellent separation capability of the present method as shown in the examples.

Where the term "comprise" or "comprising" is used in the present description and claims, it does not exclude other elements or steps. For the purpose of the present invention, the term "consisting of" is considered to be an optional embodiment of the term "comprising". If hereinafter a group is defined to comprise at least a certain number of embodiments, this is also to be understood to disclose a group which optionally consists only of these embodiments.

Where an indefinite or a definite article is used when referring to a singular noun e.g. "a" or "an", "the", this includes a plural form of that noun unless specifically stated.

Vice versa, when the plural form of a noun is used it refers also to the singular form.

Furthermore, the terms first, second, third or (a), (b), (c) and the like in the description and in the claims are used for distinguishing between similar elements and not necessarily for describing a sequential or chronological order.

In the context of the present invention any numerical value indicated is typically associated with an interval of accuracy that the person skilled in the art will understand to still ensure the technical effect of the feature in question. As used herein, the deviation from the indicated numerical value is in the range of ± <NUM>%, and preferably of ± <NUM>%. The aforementioned deviation from the indicated numerical interval of ± <NUM>%, and preferably of ± <NUM>% is also indicated by the terms "about" and "approximately" used herein with respect to a numerical value.

According to the first aspect, the present invention provides a method for the quantitative determination of human serum albumin (HSA) monomer in a liquid composition comprising at least one virus and at least one pharmaceutically acceptable carrier other than HSA, wherein the method comprises the steps of:.

In a preferred embodiment the at least one virus is selected from a flavivirus. Flaviviruses include dengue virus, Yellow Fever virus, Japanese Encephalitis virus, Murray Valley encephalitis virus and West Nile virus. In a more preferred embodiment the flavivirus is a dengue virus.

"An attenuated virus" herein means that the virus has a reduced replication capacity and/or a reduced infectivity in host cells compared to wild-type virus. The replication capacity and/or infectivity may be determined in vitro in suitable cell systems or in vivo in suitable animal models. Attenuation may be achieved by serial passaging of the virus in a foreign host such as in tissue culture, embryonated eggs or live animals. Alternatively, attenuation may be performed by chemical agents.

"Live attenuated" viruses are important for use in viral vaccines, since the live attenuated virus generates a stronger immune response compared to an inactivated virus. As used herein, the term "live attenuated virus" can refer to e.g. a chimeric virus or a non-chimeric virus.

In embodiments where the flavivirus composition comprises more than one live, attenuated virus, the composition in a preferred embodiment comprises at least one chimeric live attenuated flavivirus. More preferably, the composition comprises one chimeric flavivirus and three non-chimeric flaviviruses. Particularly preferred, the composition comprises live, attenuated DENV-<NUM>, DENV-<NUM> and DENV-<NUM> viruses and a chimeric DENV-<NUM>/DENV-<NUM> chimeric virus.

In an alternative preferred embodiment the composition comprises at least two chimeric live, attenuated viruses and at least one non-chimeric flavivirus. More preferably, the composition comprises a live, attenuated DENV-<NUM> virus, a chimeric DENV-<NUM>/DENV-<NUM> virus, a chimeric DENV-<NUM>/DENV-<NUM> virus and a chimeric DENV-<NUM>/DEN-<NUM> virus.

"Dengue virus" herein includes any wild-type or dengue virus mutant. The mutant may naturally occur or obtained by genetic engineering of the wild-type virus. The genetic modifications include additions, deletions, insertions and/or substitutions. The modifications are not particularly limited.

The term "dengue virus" also includes chimeras with genetic information from at least one further virus. The chimera may contain genetic information from another flavivirus such as Yellow Fever virus, Japanese Encephalitis virus, Murray Valley encephalitis virus and West Nile virus. Preferably, the chimera includes at least the E gene from another dengue virus strain.

Most preferably, the term "dengue chimera" is a dengue/dengue chimera derived from two different dengue viruses. Multivalent compositions comprising three or tetravalent compositions comprising four dengue/dengue chimeras are particularly envisaged.

The dengue virus is a single stranded, positive sense RNA virus of the family flaviviridae. The family flaviviridae includes three genera, flavivirus, hepacivirus and pestivirus. The genus flavivirus contains highly pathogenic and potentially hemorrhagic fever viruses, such as yellow fever virus and dengue virus, encephalitic viruses, such as Japanese encephalitis virus, Murray Valley encephalitis virus and West Nile virus, and a number of less pathogenic viruses.

The flavivirus genome comprises in <NUM>' to <NUM>' direction:.

The viral structural proteins are C, prM and E, and the nonstructural proteins are NSl to NS5. The structural and nonstructural proteins are translated as a single polyprotein and processed by cellular and viral proteases.

The dengue virus also includes dengue virus chimera comprising more than one dengue virus subtype. Suitable variants of dengue virus chimera are described in detail in <CIT>. The disclosure of which is incorporated herein by reference. Preferably, the methods according to the invention are used for determining the virus titer of the dengue virus variants TDV-<NUM>, TDV-<NUM>, TDV-<NUM> and TDV-<NUM> outlined below.

The term also includes dengue virus chimera comprising genetic information from another flavivirus. Preferably, the other flavivirus is selected from Japanese encephalitis virus, Tick-borne encephalitis virus, West Nile virus, Yellow fever virus and Zika virus.

"Dengue virus vaccine composition" herein includes monovalent compositions comprising only a single dengue virus or a dengue virus chimera. It also includes a flavivirus chimera comprising at least the E gene from dengue virus. The term also includes multivalent composition comprising more than one single dengue virus or chimera or flavivirus chimera comprising at least the E gene from dengue virus. Preferably, the multivalent compositions include dengue virus from more than one subtype, wherein the subtype is selected from DENV-<NUM>, DENV-<NUM>, DENV-<NUM> and DENV-<NUM>. More preferably, the multivalent composition is a tetravalent composition comprising dengue viruses and/or chimeras from each dengue virus subtype.

The dengue virus structural envelope (E) protein and pre-membrane (prM) protein have been identified as the primary antigens that elicit a neutralizing protective antibody response. For creation of the tetravalent dengue vaccine (TDV), TDV-<NUM> was modified by replacing the nucleic acid sequence encoding the DENV-<NUM> prM and E glycoproteins with the nucleic acid sequence encoding the corresponding wild type prM and E glycoproteins from the DENV-<NUM>, DENV-<NUM>, and DENV-<NUM> wild type strains DENV-<NUM><NUM>, DENV-<NUM><NUM> or DENV-<NUM><NUM> virus, respectively, using standard molecular genetic engineering methods (<NPL>).

"at least one pharmaceutically acceptable carrier other than HSA". The skilled person is aware of pharmaceutically acceptable carriers suitable for the preparation of pharmaceutical formulations, in particular liquid formulations or formulations to be lyophilized. The term includes any suitable diluent or excipient including any pharmaceutical agent that does not in itself induce the production of antibodies harmful to the individula receiving the composition, and which may be administered without undue toxicity.

The term includes, but is not limited to : vehicle solvents such as water, alcohol, glycerin, propylene glycol; co-solvents such as glycerol, propylene glycol, ethanol, polyethylene glycols; surfactants such as anionic, cationic, zwitterionic or nonionic. The term also includes preservatives and viscosity modifiers or suspending agents. The term further includes substances to stabilize pH, or to function as adjuvants, wetting agents, or emulsifying agents, which can serve to improve the effectiveness of the vaccine. Preferably, the pharmaceutically acceptable carrier other than HSA is selected from the group consisting of trehalose, poloxamer, urea, arginine hydrochloride, tromethamine, Tris-hydrochloride, chloride salts, and phosphate salts or any combination thereof. Preferably, trehalose is α,α-trehalose dihydrate. Preferably, poloxamer is poloxamer <NUM>, also known by its trade names Pluronic F127 and Synperonic PE/F127. Preferably, the chloride salts may comprise or consist of one or both of potassium chloride and sodium chloride. Preferably, the phosphate salts may comprise or consist of one or both of potassium dihydrogen phosphate and disodium hydrogen phosphate.

In one preferred such embodiment, the excipients are a combination of trehalose, at least one poloxamer, and human serum albumin. More preferably, the excipients are a combination of trehalose, poloxamer, human serum albumin, chloride salts, and phosphate salts. Most preferably, the excipients are a combination of α,α-trehalose dihydrate, poloxamer <NUM>, human serum albumin, potassium chloride, sodium chloride, potassium dihydrogen phosphate, and disodium hydrogen phosphate.

In another preferred such embodiment, the excipients are a combination of trehalose, at least one poloxamer, urea, arginine hydrochloride, tromethamine, Tris-hydrochloride and human serum albumin. More preferably, the excipients are a combination of trehalose, poloxamer, urea, arginine hydrochloride, tromethamine, human serum albumin, chloride salts and phosphate salts. Preferably, the chloride salts comprise or consist of sodium chloride and potassium chloride. Preferably, the phosphate salts comprise or consist of potassium dihydrogen phosphate and disodium hydrogen phosphate. Most preferably, the excipients are a combination of α,α-trehalose, poloxamer <NUM>, urea, L-arginine hydrochloride, tromethamine, Tris-hydrochloride, human serum albumin, potassium dihydrogen phosphate, disodium hydrogen phosphate, potassium chloride and sodium chloride.

The liquid composition may be obtained by mixing the one or more virus with a pharmaceutically acceptable carrier in a suitable solvent. The liquid composition herein includes a reconstituted lyophilized composition. Reconstitution may be achieved with a suitable solvent or buffer.

Size-exclusion chromatography columns may be obtained commercially or be prepared by the skilled person. The column material according to the present invention is a silica gel to which diol residues are covalently bound. Preferably, the diol residues are dihydroxypropyl residues. Such a modified column material is commercially available e.g. as YMC-Pack Diol (YMC Co. This material available as Pack Diol-<NUM>, Diol-<NUM>, Diol-<NUM> and Diol-<NUM>. Preferably, the material is YMC Pack Diol-<NUM>.

The column is preferably installed in an HPLC system which are commercially available such as e.g. Thermo Fisher/Dionex HPLC system with UV detector (DAD).

The column temperature is preferably about <NUM>±<NUM>. As injection volume of the liquid composition, preferably about <NUM> to <NUM>µL, more preferably about <NUM>µL.

Prior to the application of the liquid composition, the column material may be washed and equilibrated. (b) performing size-exclusion chromatography with a mobile phase comprising a phosphate salt and a sulfate salt at a pH value from about <NUM> to about <NUM>;.

Preferably, the mobile phase comprises about <NUM> to about <NUM> phosphate buffer with about <NUM> to about <NUM> sodium sulfate at a pH value from about <NUM> to about <NUM>. More preferably, the mobile phase consists of about <NUM> phosphate buffer with about <NUM> sodium sulfate at a pH value of about <NUM>.

Preferably, the size exclusion chromatography is performed in an isocratic manner, i.e. without changing the mobile phase.

In one preferred embodiment the size-exclusion chromatography in step (b) is performed at a flow rate of about <NUM> to about <NUM>/min. More preferably, the flow rate is about <NUM>/min. (c) detecting the UV absorption of the HSA monomer at the outlet of the column; and.

In one preferred embodiment the used detector is a diode array detector (DAD). Preferably, the absorption of the eluate at a wavelength of about <NUM> to about <NUM>, more preferably of about <NUM> is detected. Before a complex sample is separated by size-exclusion chromatography the retention time of HSA monomer of standard solutions is determined.

Preferably, at a flow rate of <NUM>/min the HSA monomer elutes with a retention time of the peak at about <NUM> to <NUM>; at a flow rate of <NUM>/min the HSA monomer elutes with a retention time of the peak at about <NUM> to about <NUM>; at a flow rate of <NUM>/min with a retention time of the peak at about <NUM> to about <NUM>.

As can be seen from the appended <FIG>, the HSA monomer peak is baseline separated from the further peaks in the chromatogram. (d) calculating the amount of HSA monomer from the area under the curve (AUC) of the detected signal.

The calculation of the amount of the HSA monomer may be carried out any suitable HPLC software may be used, in which the mathematical relationship between the inserted substance quantity and the determined peak area of the HSA peak is stored.

Preferably, the Chromeleon software (Thermo Fisher, Inc. ) may be used.

In one more preferred embodiment the inventive method comprises the steps of.

In a further aspect the present invention provides the use of the inventive method in the quality control of a virus preparation containing HSA or a vaccine composition containing HSA. The reliable determination of HSA monomer is highly relevant at different stages of the vaccine manufacturing and filling of the final product. In addition, it is important for assessing the HSA monomer concentration of the monovalent drug substance and before and after the final formulation of the tetravalent drug product.

The determination of HSA monomer is also relevant for HSA containing buffers used for the preparation of the final virus containing buffers. Preferably, the method according to the present invention may be used for the determination of the HSA monomer in the Fixed Excipient Buffer (FEB) or in the Variable Excipient Buffer (VEB).

The composition of the FEB is <NUM>/L α,α-trehalose, dihydrate, <NUM>/L Kolliphor P407 (F127), <NUM>/L HSA, <NUM> potassium dihydrogen phosphate, <NUM> disodium hydrogen phosphate, dihydrate, <NUM> potassium chloride and <NUM> sodium chloride. The composition of the VEB (utilizing a <NUM> % HSA stock solution) is <NUM>/L α,α-trehalose, dihydrate, <NUM>/L Kolliphor P407 (F127), <NUM>/L HSA, <NUM> potassium dihydrogen phosphate, <NUM> disodium hydrogen phosphate, dihydrate, <NUM> potassium chloride and <NUM> sodium chloride.

In a further aspect the present invention provides the use of the inventive method for monitoring the long-term stability of the HSA monomer in virus-containing pharmaceutical formulations. It is also of utmost importance to monitor the long-term stability of the HSA monomer to determine the relevant shelf-life of the virus-containing pharmaceutical composition.

In a further aspect the present invention provides a quality control for vaccines containing live, attenuated dengue virus comprising performing the method according to the present invention and at least one further method selected from the group consisting of identity assay, immunofocus assay, visual inspection, determination of reconstitution time or resuspendability of lyophilisates, sterility test, test for bacterial endotoxins, determination of host cell DNA, determination of pH, colorimetric determination of water, determination of osmolality, determination of the content of one or more excipient(s).

In an embodiment, the quality control method comprises or consists of the method of the first aspect of the invention and at least two further methods selected from the group consisting of identity assay, immunofocus assay, visual inspection, determination of reconstitution time or resuspendability of lyophilisates, sterility test, test for bacterial endotoxins, determination of host cell DNA, determination of pH, colorimetric determination of water, determination of osmolality, determination of the content of one or more excipient(s). In an embodiment, the quality control method comprises or consists of the method of the first aspect of the invention and at least three further methods selected from the group consisting of identity assay , immunofocus assay, visual inspection, determination of reconstitution time or resuspendability of lyophilisates, sterility test, test for bacterial endotoxins, determination of host cell DNA, determination of pH, colorimetric determination of water, determination of osmolality, determination of the content of one or more excipient(s). In an embodiment, the quality control method comprises or consists of the method of the first aspect of the invention and at least four further methods selected from the group consisting of identity assay, immunofocus assay, visual inspection, determination of reconstitution time or resuspendability of lyophilisates, sterility test, test for bacterial endotoxins, determination of host cell DNA, determination of pH, colorimetric determination of water, determination of osmolality, determination of the content of one or more excipient(s). In an embodiment, the quality control method comprises or consists of the method of the first aspect of the invention and at least five further methods selected from the group consisting of identity assay, immunofocus assay, visual inspection, determination of reconstitution time or resuspendability of lyophilisates, sterility test, test for bacterial endotoxins, determination of host cell DNA, determination of pH, colorimetric determination of water, determination of osmolality, determination of the content of one or more excipient(s). In an embodiment, the quality control method comprises or consists of the method of the first aspect of the invention and at least six further methods selected from the group consisting of identity assay, immunofocus assay, visual inspection, determination of reconstitution time or resuspendability of lyophilisates, sterility test, test for bacterial endotoxins, determination of host cell DNA, determination of pH, colorimetric determination of water, determination of osmolality, determination of the content of one or more excipient(s). In an embodiment, the quality control method comprises or consists of the method of the first aspect of the invention and at least seven further methods selected from the group consisting of identity assay, immunofocus assay, visual inspection, determination of reconstitution time or resuspendability of lyophilisates, sterility test, test for bacterial endotoxins, determination of host cell DNA, determination of pH, colorimetric determination of water, determination of osmolality, determination of the content of one or more excipient(s). In an embodiment, the quality control method comprises or consists of the method of the first aspect of the invention and at least eight further methods selected from the group consisting of identity assay, immunofocus assay, visual inspection, determination of reconstitution time or resuspendability of lyophilisates, sterility test, test for bacterial endotoxins, determination of host cell DNA, determination of pH, colorimetric determination of water, determination of osmolality, determination of the content of one or more excipient(s). In an embodiment, the quality control method comprises or consists of the method of the first aspect of the invention and at least nine further methods selected from the group consisting of identity assay, immunofocus assay, visual inspection, determination of reconstitution time or resuspendability of lyophilisates, sterility test, test for bacterial endotoxins, determination of host cell DNA, determination of pH, colorimetric determination of water, determination of osmolality, determination of the content of one or more excipient(s). In an embodiment, the quality control method comprises or consists of the method of the first aspect of the invention and all of identity assay, immunofocus assay, visual inspection, determination of reconstitution time or resuspendability of lyophilisates, sterility test, test for bacterial endotoxins, determination of host cell DNA, determination of pH, colorimetric determination of water, determination of osmolality, determination of the content of one or more excipient(s).

In one embodiment, the one or more excipients may be selected from the group consisting of trehalose, poloxamer, urea, arginine hydrochloride, tromethamine, Tris-hydrochloride, human serum albumin, chloride salts, and phosphate salts or any combination thereof. Preferably, trehalose is α,α-trehalose dihydrate. Preferably, poloxamer is poloxamer <NUM>, also known by its trade names Pluronic F127 and Synperonic PE/F127. Preferably, the chloride salts may comprise or consist of one or both of potassium chloride and sodium chloride. Preferably, the phosphate salts may comprise or consist of one or both of potassium dihydrogen phosphate and disodium hydrogen phosphate.

In another preferred such embodiment, the excipients are a combination of trehalose, at least one poloxamer, urea, arginine hydrochloride, tromethamine, Tris-hydrochloride, and human serum albumin. More preferably, the excipients are a combination of trehalose, poloxamer, urea, arginine hydrochloride, tromethamine, human serum albumin, chloride salts and phosphate salts. Preferably, the chloride salts comprise or consist of sodium chloride.

The invention is further described in the following examples which are solely for the purpose of illustrating specific embodiments of the invention, and are also not to be construed as limiting the scope of the invention in any way.

The following Examples are included to demonstrate certain aspects and embodiments of the invention as described in the claims. It should be appreciated by those of skill in the art, however, that the following description is illustrative only and should not be taken in any way as a restriction of the invention.

The methods used to generate the chimeric dengue strains TDV-<NUM>, -<NUM> and -<NUM> were standard molecular cloning and DNA engineering methods and are described in <NPL>.

The amino acid sequences of TDV-<NUM> to TDV-<NUM> used in the present example are shown in Table <NUM> above and the accompanying sequence listing.

A size exclusion high-pressure liquid chromatography (SE-HPLC) method is used to identify and measure the amounts of HSA in TDV drug product. Samples are analyzed using a <NUM>-minute isocratic method using <NUM> phosphate buffer at pH <NUM> containing <NUM> sodium sulfate as the mobile phase at a flow rate of <NUM>/minute. The reconstituted lyophilized drug product material is injected as neat sample into the YMC-Pack-Diol <NUM> (<NUM> × <NUM>, <NUM>, <NUM> pore size) size exclusion column which is monitored at UV <NUM>. HSA separates into the monomer, dimer and oligomer peaks under these conditions. Accurate quantitation is achieved by comparing the test sample peak area to an external standard curve, prepared using albumin standards and assayed at the same time. The monomer concentration is reported in mg/mL.

Drug product formulations are targeted to contain <NUM>/mL of HSA and are analyzed as neat samples. External standards are prepared to obtain the concentration range <NUM>-<NUM>/mL in Mobile Phase Buffer (MPB) [<NUM> Phosphate buffer/<NUM> sodium sulfate, pH <NUM>].

The aliquoted stock HSA standard is filtered through a <NUM> PES filter immediately before analysis. The aliquot is drawn up completely into the syringe and filtered. <NUM> of the filtrate is discarded and <NUM> is collected into a <NUM>-mL Eppendorf tube.

Reference solutions are prepared with mobile phase buffer (MPB) to obtain the concentration range <NUM>/mL to <NUM>/mL using the dilution scheme given below in Table <NUM>. Solution <NUM> to Solution <NUM> are used as standards for analysis.

Reference Solution <NUM> (<NUM>/mL of HSA in mobile phase buffer) is used.

The lyophilizate DP vial (<NUM>/mL) is removed from cold storage and re-suspension is performed by pipetting <NUM>µL of TDV diluent (<NUM> NaCl) into the opened vial. The reconstituted drug product sample is transferred into HPLC vials. Each sample is taken in two HPLC vials and each vial is injected twice for analysis.

A qualified high pressure chromatographic system equipped with a UV detector. The instrument operating parameters are listed in Table <NUM>.

The determination of the content is carried out using the Chromeleon software (any suitable HPLC software may be used), in which the mathematical relationship between the inserted substance quantity and the determined peak area of the HSA peak is stored. Prior to data evaluation, the chromatograms are checked to ensure that automatic integration is performed in the correct manner.

The formula is applied for Standard Solution <NUM> (<NUM>/mL) through <NUM> (<NUM>/mL), which are used for the calibration curve.

The HSA content in the sample solutions is calculated based on the calibration curve according to the following formula: <MAT>.

For each sample, <NUM> individual results are obtained which is averaged to generate one result.

It could be shown that the above described method is accurate, specific and robust for the monovalent drug substance, the tetravalent drug product and the filled and finished product. The method has accordingly been validated as a release assay for the quality control in the pharmaceutical industry.

A sumary of the obtained results is shown below in Table <NUM>:.

<NUM>µL to <NUM>µL DPV024-<NUM> BDS have been used as injection volumes.

The observed amount obtained at varied injection volumes were analyzed using basic statistics and using linear regression using ADAPT.

Results are summarised in (Table <NUM>) and linear regression results are given in (Table <NUM>).

The overall %CV corresponding to injection precision across <NUM> injection volumes ranged from <NUM>% - <NUM> % for DPV024-<NUM> BDS sample.

Linear regression analysis using varied injection volumes against Observed Amounts showed a good correlation coefficient (r) value of <NUM> corresponding to a strong linear response for the DPV024-<NUM> BDS sample. Changing the injection volume did not have any impact on the chromatograms or the retention time of the peaks. The overall % CV based on injection precision ranged from <NUM>% to <NUM> % for the two samples used. The result is shown in <FIG>.

The volume analyzed was 2x lower, (<NUM>. 5x and 2x) higher than the standard injection volume of <NUM>µl. Thus either of the volumes above and below the standard injection volume can be used to carry out the analysis demonstrating the method robustness.

Neat samples were evaluated using <NUM> different flow rates [<NUM>/min, <NUM>/min, <NUM>/min (standard flow rate), <NUM>/min and <NUM>/min] using DPV024-<NUM> BDS.

The peak areas obtained at varied flow rates were analyzed using basic statistics and using linear regression using ADAPT.

Results are summarised in Table <NUM> and linear regression results are given in Table <NUM>.

The overall %CV corresponding to flow precision across <NUM> different flow rates ranged from <NUM>% -<NUM> % for DPV024-<NUM> BDS sample.

As can be seen, the retention time of the HSA monomer depends on the applied flow rate. A flow rate of <NUM>/min was considered to be optimal for the validation of the method.

Linear regression analysis using varied flow rates against peak areas a good correlation coefficient (r) value of <NUM> for the DPV024-<NUM> BDS sample corresponding to a strong linear response. The overall % CV based on injection precision ranged from <NUM>% to <NUM> % for the two samples used. The result is shown in <FIG>.

Claim 1:
A method for the quantitative determination of human serum albumin (HSA) monomer in a liquid composition comprising at least one virus and at least one pharmaceutically acceptable carrier other than HSA, wherein the method comprises the steps of:
(a) applying the liquid composition on a size-exclusion chromatography column, wherein the column material comprises diol residues coupled to a silica gel;
(b) performing size-exclusion chromatography with a mobile phase comprising a phosphate salt and a sulfate salt at a pH value from about <NUM> to about <NUM>;
(c) detecting the UV absorption of the HSA monomer at the outlet of the column; and
(d) calculating the amount of HSA monomer from the area under the curve (AUC) of the detected signal.