A STABLE IMMUNOGENIC COMPOSITION FOR FROZEN STORAGE

Abstract: An injectable vaccine composition comprising an immunogenic conjugate in an emulsion containing advantageous oily vehicles is disclosed as suitable for frozen storage; moreover, a water-in-oil emulsion composition is found to enhance immunogenicity after storage at about -18 DEG C.

Description: STABLE IMMUNOGENIC COMPOSITION FOR FROZEN STORAGE This application claims pπoπty from the provisional application Serial No 60/173,022 which was filed on December 23, 1999 Field of Invention The invention is directed to a stable formulated immunogenic emulsion containing a combination of an antigen and an immunogenic earner protein More particularly, the invention is directed to a frozen emulsion which advantageously protects the lmmunogen dunng long-term storage Background of Invention Immunization methodology has developed from the earlier methods of vaccination against invasive organisms or particles as an effective means for generating an immune defense to more recent approaches for regulating or controlling the physiological functions and reactions of the body The immunogenic constructs can be administered in the form of an emulsion, also containing an oily vehicle and adjuvant for potentiation on the immune response as well as emulsifying and emulsion-stabilizing agents The immunogenic emulsions are usuallv either the oil-in-water or water-in-oil vanety Although water-in-oil emulsions have posed stability problems dependent on mateπals. salts, temperature and other factors water-in-mineral oil emulsions have increasingly served as effective vehicles for vaccines The best known emulsions of this type are known in the literature as the Freund's Adjuvants which have become effectively the emulsion standard The Complete Freund's Adjuvant differs from the Incomplete Freund's Adjuvant in that the Complete Freund's Adjuvant compnses immune response potentiating tuberculin mycobactenum However, since these mineral oil-based adjuvant forms are not well tolerated by the parentally immunized subject, different, more amenable, forms have been introduced especially for human use For example, U S Patent No 4,708,753 to Forsberg discloses a water-in-oil emulsion with a minor amount of emulsifying agent wherein the oil phase is continuous U S Patent No 4,808,334 to Ezaki, et al is directed to a process for compositions which are sterilized at high temperature and emulsified U S Patent No 4,960,814 to Wan et al discloses a process to prepare a water-in-oil emulsion or, more particularlv a water-in-hvdrophobic polvmer emulsion Injectable water-m-oil vaccine emulsions of low reactogemcitv containing Montanide ISA 703 with 1 8% AMS are disclosed in co-assigned U S Patents No 5 023,077 5,468 494 and No 5 688,506 U S Patents No 5 422 109 and No 5 424 067 to Brancq, et al disclose an injectable vaccine emulsion compnsing emulsifVing agent wherein the oil phase is continuous U S Patent No 4 808 334 to Ezaki, et al is directed to a process for compositions which are sterilized at high temperature and emulsified U S Patent No 4,960 814 to Wan et al discloses a process to prepare a water-in-oil emulsion or, more particularlv a water-in-hydrophobic poKmer emulsion Injectable water-in-oil vaccine emulsions of low reactogemcitv containing Montanide ISA 703 with 1 8% AMS are disclosed m co-assigned U S Patents No 5 023,077, 5,468 494 and No 5,688,506 U S Patents No 5,422 109 and No 5 424 067 to Brancq, et al disclose an injectable vaccine emulsion compnsing including e Drakeol Markol or anv mixture of squalene and squalane U S Patent No 5 88^ 90 to Hunter et al discloses injectable compositions of water-in-oil emulsions (and water- oil-water multiple emulsions) where the oilv phase of the vaccine adjuvants can include squalene mostlv together with a lesser amount of squalane Under appropriate conditions immunization compositions can be enhanced by combining them with the immunological adjuvant consisting of a saline suspension of l zed filamentous Amvcolate bacteria cells Emulsions are formed in several different ways, such as, e g , bv mechanical action or spontaneousK Stabilization of water-m-oil emulsions formulated with a hormone peptide immunogen should preferably be achieved without applying heat, x-rav, cross-linking agents, lrπtating or toxic solvents and oils in order to be pharmaceutically acceptable Emulsion formulations of immunogens such as, e g , anti-peptide hormone are effective components of vaccination success Anti-peptide hormone vaccines are herein defined as conjugates of an immunogenic carrier protein to a peptide hormone antigen comprising a hormone-immunomimic peptide An important practical consideration for applications of the anti-hormone vaccine technology is the shelf-life of the water-in-oil emulsion-based immunogemc composition after its manufacture and before its end use The present refrigerated shelf-life of such formulated emulsions is about 3-6 months at about 4°C In view of the expense of the immunogen and need for the immunogenic composition to be available for extended periods of time of treatment, it has been found desirable to obtain long term stable storage capability The major limiting factor of a prolonged storage of the formulated emulsion vaccine has been the elution of lmmunomimic peptide from the immunogemc earner It has now been discovered that there are several adjuvant oily substances useful as vehicles for emulsions which have been stable when frozen stored for a considerable time. SUMMARY OF THE INVENTION The present invention provides an emulsified immunogenic composition which has the advantageous capability of long-term frozen storage. According to an embodiment of the invention, it has been discovered that certain emulsified immunogenic compositions provide long-term frozen storage stability. It has been further discovered that the frozen storage of the emulsion according to the invention may be extended for more than the usual time, such as about one half year, to about one year or more. The frozen storage capability of the inventive emulsion composition compnses metabolizable oily substances of vehicles which are pharmaceutically acceptable. The inventive emulsion can be formulated with an oily substance or vehicles containing a mixture of squalene and squalane. More particularly, an oily substance according to the present invention for producing an immunogenic emulsion which is stable during frozen storage over a wide range of freezing temperature, is selected from Montanide ISA 25, Montanide ISA 703. Montanide ISA 719, or Montanide ISA 720. Specifically, the emulsion compositions according to this invention are found stable at the temperatures -18°, -23° and -70°C. Furthermore, the inventive composition can provide stable storage capability for an immunogen which may comprise epitopes of non-peptide or peptide antigenic moietes. One of the embodiments of the present invention comprises a stable water-in-oil emulsion comprising a peptide hormone or peptide fragment thereof which is conjugated to an immunogenic carrier protein. .Another embodiment of the invention comprises stable oil-in-water emulsion. The conjugate in the inventive water-in-oil emulsion may comprise a synthetic hormone- immunomimic peptide linked to an immunogenic carrier. A use of the composition includes parenteral administration. For example, in accordance with the invention, an injectable immunogen emulsion is formulated for immunization of an animal or human against its own hormone epitopes, comprising an emulsion with an aqueous phase comprising an antigen having low or negligible immunogenicity which is conjugated to an immunogenic protein carrier and an oily vehicle comprising a metabolizable oily substance or a mixture of different suitable oily substances. _> Furthermore, according to the invention the emulsion mixture remains stable after several cycles of freezing and thawing The inventive emulsion containing the suitable oily substances have been found to be stable after undergoing several freeze/thaw cycles In particular, the pharmaceutically acceptable oil vehicle comprises a mixture of metabolizable squalene and squalane. and surfactant additives, such as emulsifiers and emulsion stabilizers Furthermore, the squalene and/ or squalane mixture can comprise one or more vehicles selected from the group consisting of Montanide ISA 25, Montamde ISA 703, Montanide ISA 719, and Montamde ISA 720 According to embodiment, a surfactant emulsifier can be Mannide monooleate and a surfactant emulsion stabilizer can be polyoxy-40-hydrogenated castor oil An embodiment of the invention provides a stable emulsion suitable for frozen storage containing a gastrin peptide or fragment thereof conjugated to an immunogenic earner Another embodiment provides a stable emulsion suitable for frozen storage containing a GnRH epitope or part thereof conjugated to an immunogenic carrier An inventive embodiment can provide a stable emulsion suitable for frozen storage containing a gastrin 1 epitope or a gastrin 34 epitope, which is conjugated to an immunogenic earner, such as, e g , diphtheria toxoid, tetanus toxoid, bovine serum albumin, or keyhole limpet hemocyanin, horseshoe crab hemocyamn, ovalbumin, dextran, or immunogemc fragments thereof Another preferred embodiment provides a stable emulsion suitable for frozen storage containing a synthetic gonadotropin releasing hormone (GnRH) peptide or fragment thereof, which is conjugated to an immunogenic carrier, such as e g , diphtheria toxoid, tetanus toxoid, bovine serum albumin, keyhole limpet hemocvanin, horseshoe crab hemocvanin. ovalbumin or immunogemc fragments thereof Moreover, the frozen emulsion of this invention would remain stable for a storage penod ranging up to at least 12 months at freezing temperatures ranging from about -18°C to about -80°C The preferred frozen emulsions of this invention remain stable for a storage period of at least 12 months at temperatures of about -18°C, -23 °C or -70°C One of the embodiments of the invention compnses a stable emulsion suitable for frozen storage compnsing Montanide ISA 703, Montamde ISA 719 or Montamde ISA 720, which compnses pharmaceutically acceptable components, as descnbed below For example, the formulated emulsion may contain Montamde ISA 703, Montamde ISA 719 or Montanide ISA 720 and a synthetic G17 peptide-spacer analogue conjugated to an immunogemc moiety In particular, an emulsion can contain Montamde ISA 703 and human G17(l-9)-DT conjugate Analigunot of the emulsion may contain about 0 5 mg ml of conjugate Furthermore, it has been found that the immunogenic emulsion of the invention remains active when stored for an extended period at a temperature ranging from about -18° C to about -80°C. even after several freeze/thaw cycles in succession For example, the emulsion globules can remain at about 97% of droplet size of less than 1 um diameter after five freeze/thaw cycles from -18° C Furthermore, the emulsion of this embodiment compnses an intact conjugate immunogen content of about 97 5% after five -18° C freeze/thaw cycles or about 97 5% after five -70° C freeze/thaw cycles In addition, the formulated stable emulsion globules of the embodiment have retained at least 97% of their onginal size during frozen storage at least for 12 months It has been found that the anti-gastπn immunogenic emulsion of the invention surpnsingly shows an improved anti-gastnn immunogenicity after one freezing/thawing cycle at - 18° C Thus, the improved immunogemcity of the inventive emulsion will significantly increase the antibody titer as compared to the starting material BRIEF DESCRIPTION OF THE DRAWINGS Fig 1 illustrates the results of percent purity of hG17 (9)-DT conjugate in the aqueous phase extract from the emulsion after storage at -70°, -18°. 4° and 25°C, analyzed by exclusion chromatography with a TSK-GEL G3000SW X Column, Fig 2 illustrates the results of the matenal of Fig 1 bv exclusion chromatography with a TSK-GEL G2000SW column, Fig 3 illustrates percent conjugate release rate of the emulsion stored for up to 12 months at 4°C, Fig 4 illustrates the conjugate release rate at 25°C. Fig 5 illustrates the conjugate release rate at -70°C, Fig 6 illustrates the conjugate release rate at -18°C, Fig 7 illustrates the immunogemcity of emulsion after storage at 4°C for zero, 3, 6 and 12 months, Fig 8 illustrates the immunogemcity of emulsion after storage at 25°C for zero, 3 6 and 12 months, Fig 9 illustrates the immunogemcity of emulsion after storage at -70°C for zero, 3. 6 and 12 months, Fig 10 illustrates the lmmunogemcitv of emulsion after storage at - 18°C for zero 3, 6 and 12 months Fig 1 1 illustrates the local tolerance or reactogemcitv ot emulsion stored at 4°C for zero, 3 6 and 1 months Fig 12 illustrates the local tolerance or reactogemcitv of emulsion stored at 25°C for zero, 3 6 and 1 months Fig 13 illustrates the local tolerance or reactogemcitv of emulsion stored at -70°C for zero 3 6 and 12 months and Fig 14 illustrates the local tolerance or reactoge citv of emulsion stored at -18°C for zero 3 6 and 12 months DETAILED DESCRIPTION OF THE INVENTION According to this inv ention immunizations against non-peptide and peptide antigens have utilized emulsions of an aqueous phase containing an immunomimic epitope conjugated to a pharmaceutically acceptable immunogenic earner and a lipid phase containing a pharmaceutically acceptable oilv substance wherein the emulsions are formulated so as to be stable during storage with repeated freezing/thawing cycles Pharmaceutically acceptable oily vehicles are metabolizable and understood to be well tolerated systemically by the human as well as less irritating at the injection site of the human bv showing low reactogemcitv In accordance with the expenments described below the emulsions compnse oil-in-water, water-in-oil and water-in-oil-m-water configurations Immunogenic emulsions hav e been disclosed m e g L S Patent Nos 422 109 5,424 067 885 590 5 109 026, 4 708 753 4 808 334 and 4 960 814 w hich are incorporated herein in their entirety bv reference More specifically immunizations with Gastnn or GnRH immunogens in the form of injectable water-in-oil emulsions have been descnbed in co-assigned U S Patent No 5 468 494, 5,023,077, 5,609 870 and 5 688 506 which are herewith incorporated in this application by reference in their entirety Although freezing the emulsion was onginally employed as a gentle method to separate the conjugate-beanng aqueous phase from the emulsion for easier sampling and analvsis the emulsions preparations according to this invention surpnsingly did not break down even when expired to several freeze-thaw cycles This stability under the repeated freeze/thaw stress was all the more surpnsing because frozen storage of emulsions had not been previously considered an option Freezing and thawing was generally held to be detnmental to the stability of emulsions, perhaps leading to disruption of conjugates and aggregation or separation of emulsion components Moreover when it was also found that solutions of conjugates in PBS (phosphate buffered saline) could be frozen with little loss of integrity of the conjugate of an immunogemc earner coupled peptide, experiments were conducted to determine if it was also possible to stably store the frozen formulated emulsion For example, the anti-gastπn formulated emulsion was tested bv storage at about -70° C (as provided by a deep freezer) or about -18° C (as provided by a general freezer temperature) Accordingly, the emulsions of this invention have been formulated so as to keep the vaccine intact in long-term frozen storage In the context of the anti-hormane immunogemc embodiment of this invention, the conjugated lmmunogens can be synthetic peptides or fragments thereof, which may also be extended with spacer peptides, covalently attached to immunogemc protein earners The immunogenic carrier can be diphtheria toxoid, tetanus toxoid. a solvent extract of filamentous Amvcolate or H Pertussis keyhole limpet hemocvanin horseshoe crab hemocvanin bovine serum albumin, ovalbumin or dextran or immunogemc fragments thereof Dextran is a purified polysacchaπde product of Leuconostoc mesenteroides strain B-512 The prefened oligosacchaπde molecular weights of 64,000-76,000 are used as conjugate earner Other immunization enhancing additives include aluminum phosphate which serve as adsorbents for DT or TT The peptide or the fragment of the peptide is selected to compnse an lmmunomimic region of the target hormone epitope The immunogemc conjugates are administered in the foim of injectable water-in-oil or oil-m-water emulsions Comparative tests described below have demonstrated that certain metabolizable Montanide ISA preparations (Seppic, France) has been stable dunng frozen storage at -23°C or -70°C The select group of Montanide ISA. preparations include Montanide ISA 25, Montamde ISA 703, Montanide ISA 719 and Montanide ISA 720 In particular, pharmaceutically acceptable Montamde ISA 703 has been found an especially useful oily vehicle for forming a stable emulsion that is effective for immunogenic compositions Alternatively, other metabolizable combinations of squalene/squalane and additives can be utilized which are less irritating or more gentle, and thus more amenable to the human A composition according to this invention comprising 0 5 mg/ml of the above descnbed immunogemc conjugates in Montamde ISA 703 has been found to form a stable emulsion which is suitable for storage at temperatures below the freezing point In fact, as descnbed below, the formulated vaccine emulsion was found to remain stable when frozen for several months, up to at least about one year Thawed-out emulsions maintained visual integnty Storage of immunogemc emulsions at different temperatures and after one or more freeze-thaw cycles under the storage conditions descnbed below, did not significantly affect the conjugate mtegπty or cause oil phase separation in the emulsion In fact the emulsion globules did not show any significant aggregation, did not undergo a significant shift in a size distribution, or a significant loss of desirable uniformitv of conformation by exceeding the preferred initial 1 urn size In addition, the immunogemcity of the emulsion was significantly increased after at least one frozen storage cycle at -18° C More specifically, immunization with the frozen sample stored at -18° C was found to generate antibody titers which are about twice that of the emulsion which was not frozen Immunization emulsions suitable for frozen storage can be used with any of the anti- gastπn or anti-GnRH immunogemc conjugates, disclosed in U S Patent No 5 023 077 and 5.688,506 respectively The following examples illustrate the analysis of the inventive emulsions on the basis of certain cntena for their stabi tv Examples 1 and 2 employed the same preparations of emulsion The analysis included several categones such as appearance, particle size of the emulsion globules, conjugate immunogen purity in the extracted aqueous phase, release rate of con j ugate from emulsion in vitro, as well as immunogemcity and injection site tolerance in vivo Example 1 - Freeze-Thaw Cycles 1 Preparation of Emulsions The following procedure for forming an immunogenic emulsion is descnbed in the co- assigned U S Patent No 5,023,077 In particular, the immunogemc hormone peptide conjugate (l e , gastπn peptide immunogen conjugate) was dissolved in phosphate buffered saline at pH 7 2 ("PBS") to produce the initial aqueous phase The initial aqueous phase of the conjugate was dissolved in PBS at a concentration of 1 882 mg/ml The stenle emulsion was prepared by combimng the aqueous phase containing the conjugate with sterile nontoxic or non-irritant oily vehicle phase, such as, e g , Montamde ISA 703, at a ratio of 70 30 oil to aqueous phase (w/w) to comprise the final immunogemc emulsion concentration of 0 5 mg/ml In accordance with the present protocol, emulsions were prepared by mixing 410 ml in the Silverson 500 ml mixing head, at 8,000 φm for 4 minutes using Montamde ISA 703 as vehicle, the con j ugate was hG17(l- 9)Ser9-DT 2 Freeze-Thaw Treatments The vials (10 per temperature tested) were stored at -70°C (Ultra-Low Freezer), and - 18°C (standard freezer) The samples were assessed for their appearance (Tables A and B), globule size (Table C), and conjugate concentration and puπtv The vials with frozen emulsions were removed from the respectiv e freezers and allowed to come to room temperature The vials were mixed by moderate shaking One vial from each temperature was kept at 4 °C for testing, while the others were used to repeat the freeze/thaw procedure at the respective temperatures The vials were subjected to 0-5 freeze-thaw cycles 3 Appearance The appearance of the emulsion was noted immediately after samples were removed from either - ~ O° or -18°C. and again after thawing to room temperature and mixed by shaking When stored at -70°C, all components of the emulsion appeared frozen No difference in appearance was found between the frozen and subsequently thawed emulsions and the pre-freezing emulsion control Re-suspension by shaking was not required to maintain the original appearance However, not all components of the emulsion were frozen when stored at -18°C There was a noticeable difference between the frozen and subsequently thawed emulsions in appearance from the emulsion pnor to freezing But only moderate shaking was required for uniform re- suspension of the emulsion Following a specific number of freeze/thaw cycles (as indicated), the samples were stored at 4°C Under these conditions the samples maintained a white semi-viscous appearance with no signs of settling or separation Table A Appearance of Samples Frozen at -70°C ' Dunng the initial pan of the thaw process a very slight lav er of oil was visible above the emulsion when the \ lal was tipped side to side However, this oil was not \ isible once the sample had fully equilibrated to room temperature Table B Appearance of Samples Frozen at - 18°C approximately 10-20% of total volume of liquid m vial 4 Globular Size Distribution (Table O Globule size determination was performed on all samples from both freezing temperatures and the cold storage non-frozen control (4°C) There was no change in globule size distnbution after one freeze/thaw cvcle, although, there was a slight increase in the percentage of globule size greater than lμm. ranging up to 2 5% after 5 freeze/thaw cycles Table C Globule Size Distnbution Results 5 HPLC Analysis To analyze the conjugate in the emulsions by HPLC, the conjugate-bearing aqueous phase was first extracted from the emulsion by treatment of an aliquot of emulsion with an equal volume of isobutanol Following centπfugation (4,000 x g for 10 min ) to separate the aqueous and oil phases, the aqueous phase was collected and tested bv HPLC The HPLC conditions were flow rate = 0 5 ml/min butter = PBS, pH = 7 2, run duration = 35 mm , sample volume = 0 010ml, column = TSK-GEL® G3000 SW ι (10 mm x 300 mm), room temperature, injection volume =sample v olume The integrated data from the analyses was used to calculate the punty (% intact) of the conjugate extracted from the emulsions A retained aliquot of the aqueous phase (used to prepare the anti-gastnn immunogen) was used as an aqueous control for concentration determination (Stock conjugate lot no G1297-5) Comparison of the chromatograms for samples subjected to five freeze/thaw cycles with chromatograms for the control showed that freezing had no effect upon the elution profile of conjugate in the sample Moreover, under both storage conditions, there were no changes in conjugate concentration or purity after 5 freeze/thaw cycles, as seen in Tables 4 and 5 Table D Conjugate Concentration and Puntv by HPLC analysis -70 °C Table E Conjugate concentration and Puntv by HPLC analysis — 18°C By the parameters tested, the only change observed was in globule size distnbution, although it remained well within the specification of 60% less than l μm in size (observed 97 5% less than 1 μm at 5 freeze/thaw cycles) Therefore these storage conditions are acceptable for emulsions under the test cntena of this studv Example 2 - Long Term Storage A study was conducted to assess the stability of the inventive anti-gastπn immunogemc emulsion (e g , hG17(l -9) Ser 9-DT conjugate) when stored at -70°, - 18°, 4° and 25°C for a penod of 1 year The mixture was prepared and emulsified under aseptic conditions 10 emulsion sample vials were stored at each temperature The immunogenic concentration was 0 5 mg/ml emulsion volume At specified intervals, including at Time 0 (start of experiment), 1 week, 2 weeks, 1 month. 2 months 3 months 4 months 5 months, 6 months, 9 months and 12 months one sample vial was removed from each storage temperature and analyzed for appearance, emulsion globule size and conjugate puntv The conjugate release from the emulsion and the immunogemcity of the emulsion was analyzed at 0, 1, 3, 6, and 12 months The results of this expeπment regarding conjugate release and immunogemcity after storage at the four different temperatures are summanzed below Reference is taken to the protocol and data which are provided in the Tables below and in the figures 1 Appearance (Table 1 ) The appearance was assessed bv the following protocol ( 1 ) Remove one vial of emulsion from each storage temperature (2) Record the appearance of the emulsion samples (3) Allow samples to thaw to room temp for approximately one hour (4) Shake all emulsion samples bv hand for _ 7.--_• . minutes (5 ) Record the appearance of the emulsion samples After stabilization at each storage temperature, the appearance of the emulsion was visually assessed at each test storage temperature and compared to the initial emulsion at Time 0 The results can be summanzed. as follows Sample of initial emulsion (Time 0) Homogeneous, white, semi-viscous liquid Sample at -70°C White homogenous solid No change upon storage for 12 months Sample at - 18°C Clear amber oil layer on top of the frozen white homogeneous solid No further change upon storage for 12 months Sample at 4° C Homogeneous, white, semi-viscous liquid. No change upon storage for 12 months Sample at 25°C Homogeneous, white, semi-viscous liquid After 5 months of storage, a small amount of creaming became apparent (ι e , settling of aqueous phase droplets in the oil continuous phase ) .After 12 months storage, the creaming had progressed slowly, with a small oil layer visible on top of the emulsion After the emulsion sample vials were removed from storage, allowed to thaw/stabilize to room temperature and shaken by hand, all samples regained their original appearance, as a white , semi-viscous liquid Subsequent tests were run on the emulsion after wanning the samples to room temperature and gentle shaking I ΛBI Γ IΛ FMUI S1ON ΛI ΛI_ΛN ( I CO c CD 00 H H c H m tn 4- X m m H c r m κ> O) 'I ABLE IB EMULSION APPEARANCE 2 Emulsion Globule Size (Table 2) It was found that the test emulsions are stable upon storage at cold temperatures However, it was necessary to resuspend the aqueous phase droplets by shaking (after equilibration at room temperature) prior to use The proportion of aqueous phase droplets with a diameter > 1 μm was determined by microscopy There was no sigmficant change in the globule size distribution over the 12 month period for the emulsion when stored at -70°C, -18°C and 4°C (see Table 2) But the emulsion stored at 25°C underwent a significant shift towards larger globules resulting in an increased proportion of droplets with a diameter > 1 μm. from 1 1% at time 0 to 28 1% after 12 months storage Thus the results showed that the aqueous phase droplets were stable at -70°C, - 18°C and 4°C. but much less stable at 25°C Table 21 Emulsion Globule Size 3 Comugate Puntv (Tables 3 and 4) The aqueous phase was extracted from the formulated emulsion for the punty analysis of the conjugate, as described in Example 1 , Item 3 Puntv was determined as the proportion of mtact conjugate present in each test sample bv measuring the extracted aqueous phase by size exclusion chromatography in an HPLC system Two columns, with diffenng separatory charactenstics, were used in the analysis (the TSK-GEL® G2000SW and TSK-GEL® G3000SWXL columns) Almost identical results were obtained with each column as tabulated below A retained sample of the aqueous phase, stored at 4°C, served as a control Summary Initial (Time 0) Conjugate puntv of 99 3% Sample at -70°C No significant change after 12 months (from 99 3% to 98 9%) (Change = -0 4%) Sample at -18°C Minimal change, from 99 3% to 98 5% after 12 months (Change = -0 8%) Sample at 4°C Change from 99 3% to 95 5% after 12 months (Change = -3 8% ) Sample at 25°C Significant change, from 99 3% to 89 0% after 12 months (Change = -10 3% ) Conclusion The conjugate purity was most stable at -70°C and -18°C, less stable at 4°C and much less stable at 25°C The conjugate purity at the vanous time points assessed bv HPLC chromatography is summarized in Tables 3 and 4 Data were obtained from a G3000SWXL or G2000S column respectively Table 3 (G3000 SWXL) Table 4 (G 2000SW 4 Coniuaate Release Rate from Emulsion The rate of conjugate release from the formulated test emulsion prepared m Example 2 and was determined by stirnng the emulsion in the presence of buffer and measuring the amount of hG17(l -9) Ser 9-DT released from the emulsion into the buffer at intervals of up to 1 month. Samples of approximately 0 05 ml were taken every 7 days and assessed by Radioimmunoassay (R1A) Materials FTA Hemagglutination Buffer (Becton Dickenson Microbiology Systems. Cockevsville. MD). Bovine Serum Albumin. Fraction V ("BSA") (e g , ICN Biochemicals. Costa Mesa. CA), Sodium azide. NaN * (M W 65 02) (e g , Mallinckrodt Inc . Pans. KY). 12 x 75 mm disposable glass tubes. ι :; l-labeled hG17 CNEN), Antι-hG17 monoclonal antibodv mix equal volumes of Mab # 400- 1 2. 3 4 ( 1 100 = 40 ul Mab in 16 ml buffer). 10 ml Reacti- Vials with triangular stir bars autoclaved. Reacti-therm heater/ stirrer (Pierce). Centntuge ( e g Sorvall RT6000 Refπgerated Centrifuge, with HI 000 rotor head). Supplemented calf serum ("SCS " ), heat activated, sterile filtered (GIBCO). Polyethylene glycol PEG (M W 8000) (e.g , Sigma) Reagent Solutions: (1 ) 5% (WΛ1 NaN-, 5 00 g NaN, were dissolved in 100 ml punfied water. (2) 1% (W V) BSA with 0 02% NaN, in FTA ("/ BSA solution " ) 9 23 g FTA and 10 g of BSA were dissolved in approximately 750 ml of purified water, 4 ml 5% NaN-, were added and the volume adjusted to 1 000 liter with water (3) 6 5% (W/V) BSA with 0 05% NaN-, in FTA ("6.5% BSA in FTA solution i 1 846 g FTA. 13 g BSA were dissolved in approximately 190 ml of Dunfieα water. 2 ml of 5% NaN, were added and the volume was adjusted to 200 ml with purified water, and steπle filtered (4) A solution of 25% w/v PEG -<- 0 02 % NaN-. (PEG MW 8.000, 250 g/L) was prepared Method A Emulsion Release Test CERT") 1 2 30 ml of stenle 6 5% BSA in FTA solution was added to sterile 10 ml Reacti- Vials, each containing a stir bar 2 The solution was overlaid with 0 200 ml stenle Anti-gastπn immunogen emulsion and the vial contents were stirred rapidly at 37°C, n = 4 vials 3 At vanous intervals, stirnng was stopped and the vials were centnfuged (1.500 x g = 2.600 rpm) for 10 minutes at room temperature to separate the emulsion from the FTA 4 50 μl samples of 6 5% BSA in FT solution were obtained aseptically from each vial under the laminar flow hood and stirring was reinitiated until the next sample time when the sampling procedure was repeated B ERT Radioimmune assay ( R1A ) The concentration of hGl 7-DT in each sample was determined bv inhibition RIA as follows 1 To 12 x 75 mm glass tubes is added (duplicate samples) a 100 ul RIA buffer (1 % BSA solution) RIA buffer was also used for all sample/reagent dilutions b 100 ul of stock hGl 7-DT inhibitor in a dilution series of (in ng/ml) 0 - 35 4 - 50 - 70 7 - 100 - 141 4 - 200 - 282 8 - 400 - 565 7 - 800, to establish a standard curve The 1 88 mg/ml G17-DT stock was used to dilute 1600 ng/ml (a 1 1 175 dilution), followed bv serial 1/v 2 dilutions For the blank (0 ng/ml) tubes add 100 ul of buffer was used instead Alternatively c 100 ul of diluted sample buffer was used from the emulsion release samples The dilutions were emploved dependent on the concentration of the emulsion The dilutions were adjusted with increased time, according to the rate at which conjugate was released from the Anti-gastnn immunogen into the buffer For example, dilutions of 1 5 to 1 100 were used at first, thereafter, the dilutions are increased based upon the results of the previous sample d Sample a quots of 100 μl of 12 'l-labeled hGl 7 (1 1 500 CPM added per tube) are measured Total counts added were αetermined from two 100 ul samples e The 100 ul aliquot of anti-gastnn Mab was used at a predetermined dilution of about 25% binding efficacy 2 The contents were mixed and incubated at room temperature for 2 hours 3 100 μl of cold (1-8°C) SCS was added tube and mixed 4 500 μl of cold (1 -8°C) 25% PEG was added to each tube and mixed until precipitated 5 The tubes were immediately centrifuged for 30 minutes 2700 x g (3,600 rpm with the Sorvall RT6000 HI 000 rotor), at 4 °C 6 Supernatants were aspirated and discarded 7 The vials were counted in an automatic gamma-counter (Wallac Model 1470 Wizard, Seπal # 4700248 Aphton equipment ≠ EQ0024) C Data Analysis The standard inhibition curve was plotted (counts bound versus inhibitor added), from which the quantity of hGl 7-DT in the emulsion release test FTA samples was determined The cumulative percent of hGl 7-DT release was also calculated, relative to the starting quantity, for each sample time % Released = Total Released x 100 Total Conjugate Added The Total Conjugate Added is the quantity present in the anti-gastnn immunogen added to the vial. Total Released = quantity of released conjugate in the vial + quantity of released conjugate removed from the vial due to sampling Quantity of released conjugate in the vial = (concentration on dav n ) x (volume of buffer remaining in vial on dav /; ) Where day n was the sampling day for which the % released was determined Quantity of released conjugate removed from the vial = [(cone, in buffer in first sample) x (0.05 ml) + + (cone, in buffer on day tι-1) x (0 05 ml)] Results Release Rate (Table 5) Initial control sample (Time 0) The release rate of conjugate from freshly made emulsion was determined A maximum of 46% of conjugate was released. These data were compared to the release rate plots of emulsion for each storage temperature tested (see Fig. 3-6). Sample at -70°C (Fig 5) Similar release kinetics were observed for samples stored for 0, 1, 3 and 6 months. No significant change was observed after 6 months. Samples stored for 12 months were found to release conjugate at a slightly higher rate and up to a higher total level than each of the other storage time points The conjugate release rate and total quantity of conjugate released from emulsion stored for 12 months differed from the time emulsion release rate to a greater degree than did the emulsion stored for shorter periods of time But in view of the differences between the initial data and those of emulsion stored for 3 and 6 months, the 12 month data do not significantly deviate from the shorter storage emulsions. Sample at -18°C (Fig. 6) ' There was no consistent pattern of conjugate release rate in an emulsion stored for shofler penods No change over 12 months storage. Sample at 4°C (Fig. 3) There is no consistent change or pattern of conjugate release for emulsion stored for each time period Thus, there is no significant change of release over the 12 month test period. Sample at 25°C (Fig. 4) Samples stored for 1 , 3, 6 and 12 months released conjugate a somewhat slower rate, and to a lower total level than the initial time zero sample value. However, there was no discernible declining trend of release rates with increased storage time as the release curves in Fig 4 essentially overlap However, in this assay, storage at 25°C altered the conjugate retaining behavior of the emulsion Table 5 EMULSION CONJUGATE RELEASE RATE - SUMMARY In view of the results from the release rate tests it was concluded that the behavior of the emulsion in the release assav was not significantly altered bv storage at anv of the four select temperatures See Figures 3-6 and Table 5 in suppoπ of this conclusion 5 Immunogemcity ( Figs 7- 10 ) Immunogenicitv was assessed on samples stored for 0. 3. 6 and 12 months at the temperatures indicated below, in rabbits (female) by measuring serum antι-hG17 antibody titers in a direct binding ELISA on days 0 14, 28. 42. 56. 70 and 84 (Bleeding the animals prior to injection on injection dates) The immunogemcity data generated bv freshly made emulsion (Time 0) was compared to that obtained by testing the stored material at the vanous temperatures (see Figs. 7-10) The dosmg schedule provided for i m injections of 0 25 ml (0 125 mg) emulsion sample on day 0, 28 and 6 Sample at -70°C (Fig 9) The immunogenicitv of emulsions stored at -70°C was variable. Antiboov levels for emulsion stored 3 months were lower tnan those at Time 0 while antibody levels for emulsion stored 6 months were slightly higher at intermediate time periods but reached the same peak value on day 84 Antibody levels at 12 months were two-fold higher than Time 0 Sample at - 18°C (Fig 10) Storage at - 18°C consistently enhanced the immunogemcity by two-fold o er the staπing mateπal for emulsion held for all three incubation times This was an unexpected finding Sample at 4°C (Fig 7) No change in immunogenicitv was observed for emulsion stored at 4°C, indicating that immunogemcity was unaffected Sample at 25°C (Fig 8) Storage at 25°C resulted in vanable immunogemcity charactenstics Antibody levels at 3 months were lower than Time 0 .Antibody levels at 6 months were two-fold higher than Time 0 antibody levels at 12 months were similar to Time 0 at intermediate time penods. but lower bv dav 84 Conclusion The immunogemcity response was unaffected bv storage at 4°C Storage at - 18°C increased immunogenicitv The finding that it was possible to enhance immunogenicitv by a single freeze-thaw cvcle (freezing at -18°C) was unexpected Although storage at -70°C and 25°C resulted in more variable responses there was no clear trend that might be predictive for length of feasible storage time in addition immunogenicitv was not altered from the Time 0 control Local Tolerance (Figs 1 1-14) Gross injection site examinations were performed on each injection site on the euthamzed subject animals on dav 84 for pathology analysis Injection site reactions were scored on a scale of 0 to 3 where 0 is normal tissue appearance and 3 is extensive in inflammation through the injected muscle The mean muscle reaction scores which assess tolerance at the injection depot (reactogemcitv ) increased with the injection number and correlated with the mean antibody titers It was found that the reaction scores for emulsions held at each storage temperature were not significantly different For example Sample at -70°C The mean injection site scores for sites 1 to 3 were 0 1 0 6 and 1 1, respectively Sample at -18°C The mean injection site scores for sites 1 to 3 were 0 2 0 7 and 1 5, respectively Sample at 4X The mean injection site scores for sites 1 to 3 were 0 3 0 6 and 1 5 respectivelv Sample at 25 " C The mean injection site scores tor sites 1 to 3 were 0 3 0 8 and 1 6 respectivelv Conclusion Storage temperature had no significant effect on the tissue local tolerance Example 3 Comparative expenments have been performed to investigate formulations of an immunogenic emulsion utilizing different oily vehicles to test storage stability at 4°C and when subjected to freeze-thaw cycles at -70°C/22°C and -23°C/22°C Specifically, the antigastπn immunogen G17(l-9)-DT, was mixed with different vehicles and subjected to freeze-thaw cvcles at -70°C and -23°C Immunogens were prepared as listed in Table 6 Accordingly, a conjugate preparation of hG17(9)-DT (Peninsula Lab ) was mixed with an adjuvant selected from various formulations of oily substances such as different Montamde ISA preparations ( Seppic France), SB62(SmιthKlιne Beecham. U K ). Freund s Adiuvant. incomplete (GIBCO Lab . Grand Island. NY), and Freund's Adiuvant complete DIFCO Lab Detroit. MI) The buffered oilv adjuvants are also referred to as oilv vehicles in the test emulsions of this disclosure The emulsion aqueous pnase was in PBS (pH 7 2), and the SBAS3 adiuvant (the formulated SB62 ) was buffered in l OmM P0 4 . 150mM NaCl, pH 6 8 Except for SBAS3 w nich has a 3ml volume test emulsions were prepared at about 10ml quantitv at 0 5mg/ml (w/w ) conjugate concentration The test emulsions were distributed in eleven vials of 0 9ml fill volume w hile the SBAS3 emulsion was distributed in 0 27ml a quots All the test emulsions were prepared bv weight and mixed using a standard hand mixing procedure in which the components are rapidly transferred between two svnnges connected by 3- wav stopcock The pnvsical measurements of the text preparations are set for in Table 6 Speciπcallv tne emulsions were mixeo in various wavs ( see Table 6 ) Oilv phase vehicles Montanide ISA 25. 28 and 35 were admixed to the aqueous phase Montanide ISA 206 206D and 264 were prepared bv mixing after heating the aqueous phase and the oilv vehicles to 30°C in a water bath Aqueous phase was admixed to Montanide ISA 703. 719, and 720 to prepare injectable water-in-oil emulsions SBAS3 emulsion as prepared bv diluting the stock aqueous phase in SB buffer, and admixing the aqueous phase to the SB62 adjuvant to produce an oil-in-water emulsion For further comparison a water-in-oil emulsion was produced bv adding half of the aqueous phase to Freund s aoiuvant mixing Doth portions and then adding the rest of the aαueous phase and mixing everything again One sample vial of each test emulsion was stored at 4°C Five vials of each test emulsion were frozen either at about -70°C (GMP Ultra-Low freezer) or at about - 18°C to -25°C (standard, cnest freezer) The actual temperature observed during the later storage was -23°C (see Table 7) When the vials were frozen thoroughly they were removed from the respective freezers and allowed to thaw to room temperature One sample vial of each temperature and emulsion was retained for analysis and the remaining samples were refrozen at the respective aforementioned temperatures The test formulations were analvzed for appearance after storage at 4°C. as well as when first frozen, secondlv after thawing but without shaking, and finally after shaking the vials with the thawed emulsions The results of the comparative study are displayed in Tables 7 and 8, below Summary of Comparative Test Emulsions It is clear from the data that not all emulsion formulations show the stable storabi ty according to this invention Accordingly, the emulsions capable of withstanding freezing have been found to include Montamde ISA 25. 719 and 720 in addition to substances described in Examples 1 and 2 Thus, an oil-in-water emulsion of antι-G17 immunogen in Montamde ISA 25 (emulsion #1) has been found stable at -70°C and -23°C Water-in-oil emulsions with Montanide ISA 703, 719 and 720 (emulsions 1, 8, 9 and 10, respectively) have been found stable during frozen storage at -70°C and -23 °C However, of the other emulsions tested, none were stable at all three storage temperatures (ι_e_ -70°C, -23 °C, and ^4°C ) Table 7 Stability Test of Anti-G 17 Emulsions with Different Vehicles Subjected to Ft eeze/Thaw Cycles at -70°C and -23"C CO c C- CO H H C H m GO I m rπ H c m tυ O) Table 8 Stability Test ol Anti-G 17 Emulsions with Different Vehicles Stored at 4°C (A CD (A H H C H m O _. x o m rπ _σ c m r co

Claims: WHAT IS CLAIMED IS 1 A stable immunogenic emulsion composition suitable for frozen storage compnsing an emulsion which compnses an aqueous phase containing an immunomimic epitope conjugated to an immunogenic protein earner and a pharmaceuticallv acceptable oilv vehicle which supports a stable emulsion dunng frozen storage 2 The composition according to claim 2, wherein the immunomimic epitope is a non-peptide moiety 3 The composition according to claim 1 , wherein the immunomimic epitope is a peptide 4 The composition according to claim 3, wherein the immunomimic peptide contains the epitope of gastrin 5 The composition according to claim 3 or 4, wherein the epitope is selected from the group consisting of gastrin 17 ("G17") and gastrin 34 ("G34") 6 The composition according to claim 1, wherein the immunomimic peptide contains the epitope of gonadotropin releasing hormone (GnRH) 7 The composition according to claim 1, wherein the immunogenic protein earner is a foreign protein capable of evoking an effective immune response 8 The composition according to claim 1 or 7, wherein the immunogenic protein is selected from the group consisting of diphthena toxoid, tetanus toxoid, keyhole limpet hemocyanin, horseshoe crab hemocyanin, bovine serum albumin, extract of filamentous anvcoiate extract of H Pertussis, and dextran 9 The composition according to claim 1 wherein the oilv vehicle comprises squalene and/or squalane 10 The composition according to claim 1 or 9, wherein the oily vehicle compnses Montanide ISA 703, Montanide ISA 25, Montanide ISA 719, or Montamde ISA 720 1 1 The composition according to claim 1 or 9, wherein the oily vehicle compnses Montanide ISA 703 12 The composition according to claim 1, wherein the emulsion compnses the conjugate as an aqueous solution and the oily vehicle in equal volumes 13 The composition according to claim 1, wherein the emulsion comprises the conjugate as an aqueous solution and the oily vehicle in unequal volumes 14 The composition according to claim 1 wherein the frozen storage lasts at least one year 15 The composition according to claim 1, wherein the conjugate comprises a spacer peptide linking the immunomimic peptide to the immunogenic protein earner 16 An injectable immunogenic emulsion formulated for frozen storage compnsing (a) an aqueous phase compnsing a hormone peptide or fragment thereof which is conjugated to an immunogenic protein earner, and (b) an oily vehicle comprising a pharmaceutically acceptable oil or a mixture of pharmaceutically acceptable oils, wherein the emulsion is stable during frozen storage 17 The emulsion according to claim 16 wherein the aqueous phase and the oily vehicle are present at a weight ratio of about 70 30 for an oil-in- water emulsion 18 The emulsion according to claim 16 wherein the aqueous phase and the oily vehicle are present at a weight ratio of about 30 70 for a water-in-oil emulsion 19 The injectable emulsion of claim 16 wherein the frozen storage compnses a temperature ranging from about -18°C to about -80°C 20 The injectable emulsion of claim 16, wherein the frozen storage compnses a temperature of about -18°C 21 The injectable of claim 16, wherein the frozen compnses a temperature of about -70°C 22 The injectable emulsion of claim 16, wherein the long term frozen storage ranges from 3- 12 months 23 The injectable emulsion of claim 16, wherein after frozen storage at about -18°C, the emulsion exhibits a significant immunogenicitv increase 24 The injectable emulsion of claim 16 which has been sterile filtered 25 The injectable emulsion of claim 16, wherein the hormone peptide or fragment thereof compnses an epitope of gastrin 26 The injectable emulsion of claim 16, wherein the hormone peptide or fragment thereof compnses an epitope of G17 27 The injectable emulsion of claim 16, wherein the hormone peptide or fragment thereof compnses an epitope of G34 28 The injectable emulsion of claim 16, wherein the hormone peptide or fragment thereof compnses an epitope of the human GnRH 29 The injectable emulsion of claim 16, wherein the immunogenic protein earner is selected from diphthena toxoid ("DT"), tetanus toxoid ("TT"), bovine serum albumin ("BSA"), keyhole limpet hemocvanin ("KHC"), extracts of H Pertussis extract of filamentous Amvcolate, dextran, horseshoe crab hemocyanin, and ovalbumin 30 The injectable emulsion of claim 16 wherein the emulsion compnses a G17 peptide fragment ranging from amino acid 1 -9 of the amino terminal sequence which is conjugated at the ninth ammo acid through a spacer to the DT earner 31 The injectable emulsion of claim 16 wherein after storage at about - 18°C the emulsion is effective in significantly increasing the antι-G17 antibodv titer in an immunized animal 32 The composition according to claim 1 wherein the emulsion stored at about -18°C exhibits an increased immunogenicitv 33 A method for prolonged stable storage of an immunogen or vaccine compnsing prepaπng a composition as claimed in claim 1 34 The method for prolonged storage of an immunogen or vaccine according to claim 16, wherein the composition compnses an iniectable formulated immunogenic emulsion which is stored frozen

Inventors: BLACKBURN PETER, GRIMES STEPHEN, BLACKBURN, PETER, GRIMES, STEPHEN
Applicants: APHTON CORP, APHTON CORPORATION
Application year: 2000
Main classification: A61K9
IPC codes: A61K9, A61K38, A61K39, A61K47