Notice of Pre-AIA or AIA Status
The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA .
Continued Examination Under 37 CFR 1.114
A request for continued examination under 37 CFR 1.114, including the fee set forth in 37 CFR 1.17(e), was filed in this application after final rejection. Since this application is eligible for continued examination under 37 CFR 1.114, and the fee set forth in 37 CFR 1.17(e) has been timely paid, the finality of the previous Office action has been withdrawn pursuant to 37 CFR 1.114. Applicant's submission filed on 1/21/2026 has been entered.
Status of Claims
Cancelled: 4-5 and 20-21
New: 24
Examined Herein: 1-3, 6-19, 22-24
Priority
Priority to GB1821049.2 filed on 12/21/2018 and PCT/EP2019/086716 filed on 12/20/2019 is
acknowledged.
Information Disclosure Statement
The information disclosure statement (IDS) submitted on 6/18/2021, 11/18/2022, and 12/11/2023 is in compliance with the provisions of 37 CFR 1.97. Accordingly, the information disclosure statement is being considered by the examiner.
Drawings
The drawings filed on 6/18/2021 are accepted.
Withdrawn Rejections
The rejection of claims 1-10, 17-19, 22, and 23 under 35 U.S.C. 103 over Healey and Sigvardsson are hereby withdrawn in view of Applicant’s amendments to claim 1, which narrows the pH and buffer concentration to a range not taught or suggested by Healey and Sigvardsson.
Claim Rejections - 35 USC § 112
The following is a quotation of 35 U.S.C. 112(b):
(b) CONCLUSION.—The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the inventor or a joint inventor regards as the invention.
Claim 24 rejected under 35 U.S.C. 112(b) as being indefinite for failing to particularly point out and distinctly claim the subject matter which the inventor or a joint inventor regards as the invention.
Claim 24 recites the limitation “wherein the target microbubble concentration after refrigerated storage is 6-10 µL/mL.” There is insufficient antecedent basis for this limitation in the claim. Claim 1 does not state that the contrast agent is refrigerated or stored.
Claim Rejections - 35 USC § 103
The following is a quotation of 35 U.S.C. 103 which forms the basis for all obviousness rejections set forth in this Office action:
A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102, if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains. Patentability shall not be negated by the manner in which the invention was made.
The factual inquiries for establishing a background for determining obviousness under 35 U.S.C. 103 are summarized as follows:
1. Determining the scope and contents of the prior art.
2. Ascertaining the differences between the prior art and the claims at issue.
3. Resolving the level of ordinary skill in the pertinent art.
4. Considering objective evidence present in the application indicating obviousness or nonobviousness.
Claims 1-3, 6-9, 23, and 24 are rejected under 35 U.S.C. 103 as being unpatentable over Gupte (US 2014/0234224 A1, Published 8/21/2014).
With respect to claim 1, Gupte discloses a contrast agent in an aqueous dispersion comprising:
phospholipid-stabilized nanobubbles of perfluorocarbon (perfluorodecalin),
wherein:
the nanobubbles comprise a gas core enclosed by a single phospholipid monolayer membrane having a net neutral charge (phosphatidylcholine)
the nanobubbles having a median size of 0.183-0.236 μm
the nanobubbles are stabilized by a membrane of phospholipid; and
a buffering agent (glycine) at a concentration of ~8 mM
wherein:
the contrast agent has a bulk pH of 8.4 (which falls within the scope of “a bulk pH of about 8.75 to about 9.25.” Note: The specification defines the term “about” as ± 0.1 to 0.5; Specification, 0038). [Gupte, 0199-0204, Example 14]
With respect to claim 2, the limitation "...is suitable for long term storage" recites a non-limiting description. This limitation does not limit the claim to a particular structure. As a result, the scope of claim 1 is not limited by this language. Still, Gupte discloses the contrast agent is suitable for long-term storage. [Gupte, 0079, 0081]
With respect to claim 3, the limitation “…is suitable for use in a clinical setting” recites a non-limiting description. This limitation does not limit the claim to a particular structure. As a result, the scope of claim 1 is not limited by this language. Still, Gupte discloses the composition is suitable for using a clinical setting. [Gupte, 0132-0133]
With respect to claim 7, Gupte discloses the composition further comprises a tonicity agent, glycerol.
With respect to claim 8, Gupte discloses the composition further comprises a viscosity agent, glycerol.
With respect to claim 23, the limitation “wherein the buffering agent is added to the aqueous dispersion to adjust the bulk pH of the aqueous dispersion to a pH of from about 8.9 to about 9.1 when measured at 5°C” recites a product by process. The patentability of a product does not depend on its method of production. If the product in the product-by-process claim is the same as or obvious from a product of the prior art, the claim is unpatentable even though the prior product was made by a different process. The prior art discloses the limitations of claim 1. Therefore, it is immaterial if the contrast agent was produced by a process different than the process claimed. The burden now shifts to applicant to come forward with evidence establishing a nonobvious difference between the claimed product and the prior art product.
With respect to claim 24, the limitation “wherein the target microbubble concentration after refrigerated storage is 6-10 µL/mL” recites an intended result but does not limit the claim to a particular structure (i.e. a previously refrigerated ultrasound contrast agent). As a result, the scope of claim 1 is not limited by this language.
Gupte does not explicitly disclose the phospholipid membrane has a net negative charge or the nanobubbles have a median size of 1 to 6 µm or the pefluorocarbon is perflurorobutane, perfluoropropane, or pefluopentane.
However, with respect to claim 1 and 6, Gupte discloses the phospholipid/emulsifying agent may be selected from a group including, hydrogenated phosphatidylserine or hydrogenated phosphatidylinositol. [Gupte, 0047, 0051] Hydrogenated phosphatidylserine and hydrogenated phosphatidylinositol have a negative net charge.
Moreover, with respect to claim 1, Gupte discloses the nanobubbles may have a particle size of between about 0.1 um and about 5 µm. [Gupte, 0026]
With respect to claim 9, Gupte discloses the perflurocarbon for use in the composition may be perfluoropentane. [Gupte, 0020]
Modifying the contrast agent disclosed by Gupte by replacing phosphatidylcholine with hydrogenated phosphatidylserine or hydrogenated phosphatidylinositol and adjusting the particle size of the bubbles to 0.1-5 µm results in the contrast agent of claim 1 and 6. Identical compositions must have identical properties and the modified composition disclosed by Gupte is substantially identical to the claimed composition. Therefore, the composition disclosed by Gupte would be expected to yield the same functional properties, including having a bulk pH of about 8.75 to about 9.25 when measured at 5°C.
Further modifying the contrast agent disclosed by Gupte by replacing perfluorodecalin with perfluoropentane, results in the contrast agent of claim 9.
It would be obvious to one of ordinary skill in the art to modify the contrast agent disclosed by Gupte by replacing phosphatidylcholine with hydrogenated phosphatidylserine or hydrogenated phosphatidylinositol and have a reasonable expectation of success. Gupte discloses a contrast agent comprising a phospholipid/emulsifying agent, phosphatidylcholine. Gupte further discloses the phospholipid/emulsifying agent may be selected from a group including hydrogenated phosphatidylserine or hydrogenated phosphatidylinositol. In view of this express teaching, it is reasonable to expect that hydrogenated phosphatidylserine or hydrogenated phosphatidylinositol may function as the phospholipid/emulsifying agent in the contrast agent disclosed by Gupte. One would have been motivated to do so because substituting art-recognized equivalents known for the same purpose is prima facie obvious. MPEP 2144.06(II). In the present case, Gupte discloses hydrogenated phosphatidylcholine, lysophosphatidylcholine, phosphatidylserine, and phosphatidylinositol are each phospholipids, surfactants, and emulsifying agents. [Gupte, 0046, 0047, 0051] Therefore, it is prima facie obvious to substitute one known surfactants/emulsifying agent suitable for use in the composition (phosphatidylcholine) with another (hydrogenated phosphatidylserine or hydrogenated phosphatidylinositol).
It would be obvious to one of ordinary skill in the art to modify the contrast agent disclosed by Gupte by adjusting the particle size of the bubbles to 0.1-5 µm and have a reasonable expectation of success. Gupte discloses a contrast agent, wherein the particles have an effective average particle size 0.183-0.236 μm. Gupte further discloses the effective average particle size of the particles may be between about 0.1 μm and about 5 μm. In view of this express teaching, it is reasonable to expect particles of the contrast agent may achieve a particle size between about 0.1 μm and about 5 μm. One would have been motivated to do so because it is prima facie obvious to combine references when some advantage or expected beneficial result would have been produced by their combination. MPEP 2144(II). In the present case, Gupte discloses particles having an effective average size of between about 0.1 μm and about 5 μm improves oxygen delivery to tissue by two mechanisms: 1) facilitated diffusion through blood plasma from the hemoglobin in RBC's to the tissue and 2) delivery of oxygen to tissues that are not accessible to RBC's or free hemoglobin (e.g. through partially thrombosed vessels or partially collapsed capillaries). [Gupte, 0149] Therefore, one would have been motivated by the expectation that the adjusted particle size would enable the contrast agent disclosed by Gupte to exhibit improved oxygen delivery to tissue.
It would be obvious to one of ordinary skill in the art to modify the contrast agent disclosed by Gupte by replacing perfluorodecalin with perfluoropentane and have a reasonable expectation of success. Gupte discloses a contrast agent comprising a perfluorinated compound, perfluorodecalin. Gupte further discloses the perfluorinated compound may be selected from a group including dodecafluoropentane (perfluoropentane). In view of this express teaching, it is reasonable to expect that perfluoropentane may function as the perfluorinated compound in the contrast agent disclosed by Gupte. One would have been motivated to do so because substituting art-recognized equivalents known for the same purpose is prima facie obvious. MPEP 2144.06(II). In the present case, Gupte discloses perfluorodecalin and perfluoropentane are perfluorinated compounds preferred for use in the composition. [Gupte, 0020 0037] Therefore, it is prima facie obvious to substitute one known perfluorinated compounds preferred for use in the composition (perfluorodecalin) with another (perfluoropentane).
Claims 1-3, 6-10, and 22-24 are rejected under 35 U.S.C. 103 as being unpatentable over Cuthbertson (US 2003/0104359 A1, Published 6/5/2003), in view of Paul (US 2007/0110713 A1, Published 5/17/2007).
With respect to claim 1, Cuthbertson discloses a contrast agent in an aqueous dispersion comprising:
phospholipid-stabilized microbubbles of perfluorocarbon (perfluorobutane)
wherein:
the microbubbles comprise a gas core enclosed by a single phospholipid monolayer membrane having a net negative charge (DSPS or HEPS);
the microbubbles having a median size of 1 to 5 µm;
the microbubbles are stabilized by a membrane of phospholipid; and
wherein:
the contrast agent has a bulk pH of 9 (which falls within the scope of “a bulk pH of about 8.75 to about 9.25.” Note: The specification defines the term “about” as ± 0.1 to 0.5; Specification, 0038). [Cuthbertson, 0094-0102, 0160]
With respect to claim 2, the limitation "...is suitable for long term storage" recites a non-limiting description. This limitation does not limit the claim to a particular structure. As a result, the scope of claim 1 is not limited by this language.
With respect to claim 3, the limitation “…is suitable for use in a clinical setting” recites a non-limiting description. This limitation does not limit the claim to a particular structure. As a result, the scope of claim 1 is not limited by this language.
With respect to claim 6, Cuthbertson discloses the membrane of phospholipid is DSPS or HEPS.
DSPS and HEPS have a net negative charge. [Cuthbertson, 0098, 0160]
With respect to claim 7, Cuthbertson discloses the contrast agent further comprises a tonicity agent, glycerol. [Cuthbertson, 0098]
With respect to claim 8, Cuthbertson discloses the contrast agent further comprises a viscosity agent, glycerol. [Cuthbertson, 0098]
With respect to claim 9, Cuthbertson discloses the perfluorocarbon is perfluorobutane. [Cuthbertson, 0098]
With respect to claim 10, Cuthbertson discloses the perfluorocarbon is perfluorobutane and the phospholipid is hydrogenated egg phosphatidyl serine. [Cuthbertson, 0098, 0160]
With respect to claim 22, Cuthbertson discloses the phospholipid is hydrogenated egg phosphatidyl serine. [Cuthbertson, 0098, 0160]
With respect to claim 23, the limitation “wherein the buffering agent is added to the aqueous dispersion to adjust the bulk pH of the aqueous dispersion to a pH of from about 8.9 to about 9.1 when measured at 5°C” recites a product by process. The patentability of a product does not depend on its method of production. If the product in the product-by-process claim is the same as or obvious from a product of the prior art, the claim is unpatentable even though the prior product was made by a different process. The prior art discloses the limitations of claim 1. Therefore, it is immaterial if the contrast agent was produced by a process different than the process claimed. The burden now shifts to applicant to come forward with evidence establishing a nonobvious difference between the claimed product and the prior art product.
With respect to claim 24, the limitation “wherein the target microbubble concentration after refrigerated storage is 6-10 µL/mL” recites an intended result but does not limit the claim to a particular structure (i.e. a previously refrigerated ultrasound contrast agent). As a result, the scope of claim 1 is not limited by this language.
Cuthbertson does not disclose the contrast comprises (b) a buffering agent selected from the group consisting of Tris, diethanolamine, glycine, and triethanolamine, at a concentration of 5-10 mM.
However, with respect to claim 1, Paul discloses TRIS buffer, specifically 10mM TRIS, is a biocompatible buffering agent capable of adjusting a pharmaceutical formulation to a pH of 8 to 9. [Paul, 0147]
Modifying the contrast agent disclosed by Cuthbertson by adding a buffering agent, 10 mM TRIS, results in the composition of claim 1. Identical compositions must have identical properties and the modified composition disclosed by Cuthbertson and Paul is substantially identical to the claimed composition. Therefore, the composition disclosed by Gupte would be expected to yield the same functional properties, including having a bulk pH of about 8.75 to about 9.25 when measured at 5°C.
It would be obvious to one of ordinary skill in the art to modify the contrast agent disclosed by Cuthbertson by adding 10 mM TRIS buffer and have a reasonable expectation of success. Cuthbertson discloses a contrast agent that is adjusted to have a bulk pH of 9. Paul discloses TRIS buffer, specifically 10 mM Tris, is a buffering agent capable of adjusting a formulation to a pH of 8 to 9. Accordingly, the combined teachings of Cuthbertson and Paul suggest that 10 mM TRIS buffer may be used to adjust the formulation disclosed by Cuthbertson to a bulk pH of 9. Therefore, it is reasonable to expect the contrast agent disclosed by Cuthbertson may be modified by adding 10 mM TRIS buffer. One would have been motivated to do so because it is prima facie obvious to combine references when some advantage or expected beneficial result would have been produced by their combination. MPEP 2144(II). In the present case, Cuthbertson discloses the contrast agent is a biocompatible and pharmaceutical formulation. [Cuthbertson, 0017, 0033] Paul discloses buffers, including 10mM TRIS, are employed in pharmaceutical compositions to ensure the pH of the composition is suitably adjusted and buffered in order to be appropriate for use in humans or animals, preferably at a physiological or slightly basic pH (between about pH 8 to about pH 9). [Paul, 0147] Therefore, one would have been motivated by the expectation that adding 10 mM TRIS buffer to the biocompatible and pharmaceutical formulation disclosed by Cuthbertson, would enable the pH of the biocompatible and pharmaceutical formulation to be adjusted and buffered appropriately for use in humans or animals.
Claims 1-3, 6-9, 17-19, 23, and 24 are rejected under 35 U.S.C. 103 as being unpatentable over Klaveness (US 2004/0141922 A1, Published 7/22/2004), in view of Paul (US 2007/0110713 A1, Published 5/17/2007).
With respect to claim 1, Klaveness discloses a contrast agent in an aqueous dispersion comprising:
phospholipid-stabilized microbubbles of perfluorocarbon (perfluorobutane)
wherein:
the microbubbles comprise a gas core enclosed by a single phospholipid monolayer membrane having a net negative charge (DSPS);
the microbubbles having a median size of 1 to 5 µm or 1 to 7 µm;
the microbubbles are stabilized by a membrane of phospholipid; and
wherein:
the contrast agent has a bulk pH of 9 (which falls within the scope of “a bulk pH of about 8.75 to about 9.25.” Note: The specification defines the term “about” as ± 0.1 to 0.5; Specification, 0038). [Klaveness, 0421-0428, 0600-0608]
With respect to claim 2, the limitation "...is suitable for long term storage" recites a non-limiting description. This limitation does not limit the claim to a particular structure. As a result, the scope of claim 1 is not limited by this language. Still, Klaveness discloses the agent is suitable for long-term storage. [Klaveness, 0044]
With respect to claim 3, the limitation “…is suitable for use in a clinical setting” recites a non-limiting description. This limitation does not limit the claim to a particular structure. As a result, the scope of claim 1 is not limited by this language. Still, Klaveness discloses the agent is suitable for use in a clinical setting. [Klaveness, 0002, 0014]
With respect to claim 6, Klaveness discloses the membrane of phospholipid is DSPS.
DSPS has a net negative charge. [Klaveness, 0424, 0604]
With respect to claim 7, Klaveness discloses the contrast agent further comprises a tonicity agent, glycerol. [Klaveness, 0424, 0604]
With respect to claim 8, Klaveness discloses the contrast agent further comprises a viscosity agent, glycerol. [Klaveness, 0424, 0604]
With respect to claim 9, Klaveness discloses the perfluorocarbon is perfluorobutane. [Klaveness, 0604]
With respect to claim 17, Klaveness discloses a method comprising injecting the ultrasound contrast agent into the tissue of a subject and carrying out an ultrasound scan of said tissue. [Klaveness, 0002, 0008, 0009, 0018, 0049, 0105]
With respect to claim 18, Klaveness discloses a method comprising injecting the ultrasound contrast agent into the tissue of a subject, carrying out an ultrasound scan of said tissue, and generating an image of said tissue. [Klaveness, 0002, 0008, 0009, 0018, 0049, 0105]
With respect to claim 19, Klaveness discloses a method comprising injecting the ultrasound contrast agent into the tissue of a subject, carrying out an ultrasound scan of said tissue, and generating an image of said tissue. [Klaveness, 0002, 0008, 0009, 0018, 0049, 0105] The limitation “…and assessing said image in order to make a diagnosis” is not owed patentable weight because an assessment is a mental process, not an inventive step.
With respect to claim 23, the limitation “wherein the buffering agent is added to the aqueous dispersion to adjust the bulk pH of the aqueous dispersion to a pH of from about 8.9 to about 9.1 when measured at 5°C” recites a product by process. The patentability of a product does not depend on its method of production. If the product in the product-by-process claim is the same as or obvious from a product of the prior art, the claim is unpatentable even though the prior product was made by a different process. The prior art discloses the limitations of claim 1. Therefore, it is immaterial if the contrast agent was produced by a process different than the process claimed. The burden now shifts to applicant to come forward with evidence establishing a nonobvious difference between the claimed product and the prior art product.
With respect to claim 24, the limitation “wherein the target microbubble concentration after refrigerated storage is 6-10 µL/mL” recites an intended result but does not limit the claim to a particular structure (i.e. a previously refrigerated ultrasound contrast agent). As a result, the scope of claim 1 is not limited by this language.
Klaveness does not disclose the contrast comprises (b) a buffering agent selected from the group consisting of Tris, diethanolamine, glycine, and triethanolamine, at a concentration of 5-10 mM.
However, with respect to claim 1, Paul discloses TRIS buffer, specifically 10mM TRIS, is a biocompatible buffering agent capable of adjusting a pharmaceutical formulation to a pH of 8 to 9. [Paul, 0147]
Modifying the contrast agent disclosed by Klaveness by adding a buffering agent, 10 mM TRIS, results in the composition of claim 1. Identical compositions must have identical properties and the modified composition disclosed by Klaveness and Paul is substantially identical to the claimed composition. Therefore, the composition disclosed by Gupte would be expected to yield the same functional properties, including having a bulk pH of about 8.75 to about 9.25 when measured at 5°C.
It would be obvious to one of ordinary skill in the art to modify the contrast agent disclosed by Klaveness by adding 10 mM TRIS buffer and have a reasonable expectation of success. Klaveness discloses a contrast agent that is adjusted to have a bulk pH of 9. Paul discloses TRIS buffer, specifically 10 mM Tris, is a buffering agent capable of adjusting a formulation to a pH of 8 to 9. Accordingly, the combined teachings of Klaveness and Paul suggest that 10 mM TRIS buffer may be used to adjust the formulation disclosed by Klaveness to a bulk pH of 9. Therefore, it is reasonable to expect the contrast agent disclosed by Klaveness by adding 10 mM TRIS buffer. One would have been motivated to do so because it is prima facie obvious to combine references when some advantage or expected beneficial result would have been produced by their combination. MPEP 2144(II). In the present case, Klaveness discloses the contrast agent is a biocompatible and pharmaceutical formulation. [Klaveness, 0008, 0014, 0015, 0044, 0050, 0062] Paul discloses buffers, including 10mM TRIS, are employed in pharmaceutical compositions to ensure the pH of the composition is suitably adjusted and buffered in order to be appropriate for use in humans or animals, preferably at a physiological or slightly basic pH (between about pH 8 to about pH 9). [Paul, 0147] Therefore, one would have been motivated by the expectation that adding 10 mM TRIS buffer to the biocompatible and pharmaceutical formulation disclosed by Klaveness would enable the pH of the biocompatible and pharmaceutical formulation to be adjusted and buffered appropriately for use in humans or animals.
Claims 11-14 and 16 are rejected under 35 U.S.C. 103 as being unpatentable over Schneider (US 2006/0034770 A1, Published 2/16/2006), in view of Dyvik (US 2002/0039556 A1, Published 4/4/2002).
With respect to claim 11, 12, 13, and 16, Schneider discloses a method for preparing an ultrasound contrast agent, comprising the following steps:
Homogenizing perfluorocarbon continuously in a sterile aqueous dispersion of phospholipid to generate phospholipid-stabilized microbubbles of perfluoropentane dispersed in an aqueous dispersion; [Schneider, 0210]
Adjusting the size distribution of microbubbles in the aqueous dispersion to a median size in the range from 1.12-1.94 µm; [Schneider, 0210, 0211, Table 1]
Adding a tonicity agent, mannitol, to the aqueous dispersion; [Schneider, 0210]
Adjusting the concentration of microbubbles in the aqueous dispersion to achieve a target concentration of microbubble of about 0.736-3.82 µL/mL; [Schneider, 0210, 0211, Table 1] and
Dispensing the aqueous dispersion into a vial and flushing the headspace of the vial with perfluorobutane, [Schneider, 0211]
wherein the ultrasound contrast agent is in an aqueous dispersion. [Scneider, 0211]
With respect to claim 14, the limitation “…wherein the ultrasound contrast agent is for long-term storage and/or is ready to use in a clinical setting” recites a non-limiting description. The limitation does not require steps to be performed or limit the claim to a particular structure. Therefore, the scope of claim 11 is not limited by this language.
Schneider further discloses the ultrasound contrast agent produced by the aforementioned method is injectable and may be administered to a mammalian subject via intravenous injection. [Schneider, 0017, 0280]
Schneider does not disclose the method comprises a step of (iv) Adding a buffering agent selected from the group consisting of TRIS, diethanolamine, glycine, and triethanolamine to the aqueous dispersion to adjust the bulk pH of the aqueous dispersion to a pH of from about 8.75 to about 9.25 when measured at 5°C, wherein the buffering agent has a concentration of 5-10 mM.
However, Dyvik discloses that adding a buffer system comprising a water-soluble amine having a pH at 15°C of less than or equal to 9.5 stabilizes a substantially saturated phospholipid composition. [Dyvik, 0011] Dyvik further defines phospholipid compositions as liposomes or microbubble formulations. [Dyvik, 0035] Dyvik discloses a reduced degree of hydrolysis of the phospholipid is observed when compared with formulations not including the specified buffer system. [Dyvik, 0019] Additionally, Dyvik discloses the water-soluble amines which may be employed as buffers include TRIS, diethanolamine, and triethanolamine. [Dyvik, 0028] Dyvik discloses these buffers may have a concentration of 2mM to 200 mM. [Dyvik, 0032] Dyvik additionally discloses the buffer system provides the compositions with a pH of 6.0 to 9.5 at room temperature (15° C). [Dyvik, 0018]
Modifying the method disclosed by Schneider by adding a step of (iv) adding a buffering agent, TRIS, with a concentration of 5 mM to 200 mM, to the aqueous dispersion to adjust the bulk pH of the aqueous dispersion to a pH of about 8.5 to 9.8 at 5°C (which correlates to about 6.0 to 9.5 at 15°C), results in the method of claim 11. The pH of TRIS is temperature-dependent; the pH is higher at low temperatures compared to the pH at higher temperatures. The pH of TRIS changes about -0.028 per degree lower than 25°C. Therefore, the buffer system disclosed by Dyvik which provides the compositions with a pH of 6.0 to 9.5 at 15°C, provides a pH of about 6.3 to 9.8 at 5° C.
It would be obvious to one of ordinary skill in the art to modify the method disclosed by Schneider further including the step of (iv) adding a buffering agent, TRIS, with a concentration of 5 mM to 200 mM, to the aqueous dispersion to adjust the bulk pH of the aqueous dispersion to a pH of about 8.5 to 9.8 at 5°C and have a reasonable expectation of success. Schneider discloses a method for preparing an ultrasound contrast agent comprising generating phospholipid-stabilized microbubbles, wherein the phospholipid is hydrogenated egg phosphatidylcholine. Hydrogenated egg phosphatidylcholine is a substantially saturated phospholipid. Dyvik discloses that adding a buffer system comprising TRIS, diethanolamine, or triethanolamine at a concentration of 2 mM to 200 mM to a substantially saturated phospholipid composition (i.e. a phospholipid stabilized microbubble formulation), stabilizes the composition. Dyvik discloses this buffer system provides the composition with a pH of 6.0 to 9.5 at 15° C. Since the pH of TRIS is temperature dependent and changes about -0.028 per degree lower than 25°C, a pH of 6.0 to 9.5 at 15°C is equivalent to a pH of about 6.3 to 9.8 at 5° C. So, Schneider discloses a method for preparing an ultrasound contrast agent comprising a substantially saturated phospholipid, hydrogenated egg phosphatidylcholine, and Dyvik establishes that adding a buffer system, like 2 mM to 200 mM TRIS, diethanolamine, or triethanolamine buffer stabilizes a substantially saturated phospholipid composition by providing the composition with a pH of about 8.5 to 9.8 at 5°C. Thus, the combined teachings of Schneider and Dyvik suggest that adding 5 mM to 200 mM TRIS buffer will stabilize the ultrasound contrast agent prepared in the method disclosed by Schneider and provide the agent with a pH of about 8.5 to 9.8 at 5°C. Therefore, it is reasonable to expect the method disclosed by Schneider may be modified in the manned described above. One would have been motivated to do so because it is prima facie obvious to combine references when some advantage or expected beneficial result would have been produced by their combination. MPEP 2144(II). In the instant case, Dyvik discloses that adding a buffer system comprising a water-soluble amine, like TRIS, reduces the degree of hydrolysis of a phospholipid in a formulation compared to formulations not including the specified buffer system. [Dyvik, 0011, 0018, 0019] Thus, one would have been motivated by the expectation that the aforementioned modification would reduce the degree of hydrolysis of the phospholipid in the ultrasound contrast agent prepared according to the method disclosed by Schneider.
Claims 11 and 14-16 are rejected under 35 U.S.C. 103 as being unpatentable over Dugstad, in view of Dyvik.
With respect to claim 11, 15, and 16, Dugstad discloses a method for preparing an ultrasound contrast agent comprising the following steps:
Homogenizing perfluorobutane continuously in a sterile aqueous dispersion of phospholipid, hydrogenated egg phosphatidylserine, to generate phospholipid-stabilized microbubbles of perfluorobutane dispersed in an aqueous dispersion; [Dugstad, 0073-0075]
Adjusting the size distribution of microbubbles in the aqueous dispersion to a median size of 3.83 µm via sonication; [Dugstad, Page 28, Line 22-24] [Dugstad, 0075]
(VI) Dispensing the aqueous dispersion into a vial and flushing the headspace of the vial with perfluorobutane. [Dugstad, 0075]
(V) Adjusting the concentration of microbubbles in the aqueous dispersion to achieve a target concentration of microbubbles of about 6 µL/mL; and [Dugstad, 0077 & Table 2.1]
wherein, the method does not include a step of freeze-drying.
With respect to claim 14, the limitation “…wherein the ultrasound contrast agent is for long-term storage and/or is ready to use in a clinical setting” recites a non-limiting description. The limitation does not require steps to be performed or limit the claim to a particular structure. Therefore, the scope of claim 11 is not limited by this language. Still, Dugstad discloses the ultrasound contrast agent is ready to use in a clinical setting. [Dugstad, 0030]
Dugstad does not disclose the method comprises a step of (iv) Adding a buffering agent selected from the group consisting of TRIS, diethanolamine, glycine, and triethanolamine to the aqueous dispersion to adjust the bulk pH of the aqueous dispersion to a pH of from about 8.75 to about 9.25 when measured at 5°C, wherein the buffering agent has a concentration of 5-10 mM.
However, Dyvik discloses that adding a buffer system comprising a water-soluble amine having a pH at 15°C of less than or equal to 9.5 stabilizes a substantially saturated phospholipid composition. [Dyvik, 0011] Dyvik further defines phospholipid compositions as liposomes or microbubble formulations. [Dyvik, 0035] Dyvik discloses a reduced degree of hydrolysis of the phospholipid is observed when compared with formulations not including the specified buffer system. [Dyvik, 0019] Additionally, Dyvik discloses the water-soluble amines which may be employed as buffers include TRIS, diethanolamine, and triethanolamine. [Dyvik, 0028] Dyvik discloses these buffers may have a concentration of 2 mM to 200 mM. [Dyvik, 0032] Dyvik additionally discloses the buffer system provides the compositions with a pH of 6.0 to 9.5 at room temperature (15° C). [Dyvik, 0018]
Modifying the method disclosed by Dugstad by adding a step of (iv) adding a buffering agent, TRIS, with a concentration of 5 mM to 200 mM, to the aqueous dispersion to adjust the bulk pH of the aqueous dispersion to a pH of about 8.5 to 9.8 at 5°C (which correlates to about 6.0 to 9.5 at 15°C), results in the method of claim 11. The pH of TRIS is temperature-dependent; the pH is higher at low temperatures compared to the pH at higher temperatures. The pH of TRIS changes about -0.028 per degree lower than 25°C. Therefore, the buffer system disclosed by Dyvik which provides the compositions with a pH of 6.0 to 9.5 at 15°C, provides a pH of about 6.3 to 9.8 at 5° C.
It would be obvious to one of ordinary skill in the art to modify the method disclosed by Dugstad by further including the step of (iv) adding a buffering agent, TRIS, with a concentration of 5 mM to 200 mM, to the aqueous dispersion to adjust the bulk pH of the aqueous dispersion to a pH of about 8.5 to 9.8 at 5°C and have a reasonable expectation of success. Dugstad discloses a method for preparing an ultrasound contrast agent comprising generating phospholipid-stabilized microbubbles, wherein the phospholipid is hydrogenated egg phosphatidylcholine. Hydrogenated egg phosphatidylcholine is a substantially saturated phospholipid. Dyvik discloses that adding a buffer system comprising TRIS, diethanolamine, or triethanolamine at a concentration of 2 mM to 200 mM to a substantially saturated phospholipid composition, stabilizes the composition. Dyvik discloses that adding a buffer system comprising TRIS, diethanolamine, or triethanolamine at a concentration of 2 mM to 200 mM to a substantially saturated phospholipid composition (i.e. a phospholipid stabilized microbubble formulation), stabilizes the composition. Dyvik discloses this buffer system provides the composition with a pH of 6.0 to 9.5 at 15° C. Since the pH of TRIS is temperature dependent and changes about -0.028 per degree lower than 25°C, a pH of 6.0 to 9.5 at 15°C is equivalent to a pH of about 6.3 to 9.8 at 5° C. So, Dugstad discloses a method for preparing an ultrasound contrast agent comprising a substantially saturated phospholipid, hydrogenated egg phosphatidylcholine, and Dyvik establishes that adding a buffer system, like 2 mM to 200 mM TRIS, diethanolamine, or triethanolamine buffer stabilizes a substantially saturated phospholipid composition by providing the composition with a pH of about 8.5 to 9.8 at 5°C. Therefore, it is reasonable to expect the method disclosed by Dugstad may be may be modified in the manned described above. One would have been motivated to do so because it is prima facie obvious to combine references when some advantage or expected beneficial result would have been produced by their combination. MPEP 2144(II). In the instant case, Dyvik discloses that adding a buffer system comprising a water-soluble amine, like TRIS, reduces the degree of hydrolysis of a phospholipid in a formulation compared to formulations not including the specified buffer system. [Dyvik, 0011, 0018, 0019] Thus, one would have been motivated by the expectation that the aforementioned modification would reduce the degree of hydrolysis of the phospholipid in the ultrasound contrast agent prepared according to the method disclosed by Dugatad.
Response to Arguments
Applicant’s arguments with respect to 1-10, 17-19, 22, and 23 under 35 U.S.C. 103 over Healey and Sigvardsson have been considered but are moot because the new ground of rejection does not rely Healey or Sigvardsson for any teaching or matter specifically challenged in the argument.
Applicant's arguments with respect to claims 11-14 and 16 under 35 U.S.C. 103 as being over Schneider and Dyvik and claims 11 and 14-16 under 35 U.S.C. 103 over Dugstad and Dyvik filed 1/21/2026 have been fully considered but they are not persuasive.
Applicant asserts “Applicant does not assume or assert that pH values measured at different temperatures are interchangeable, and the cited art is evaluated based solely on the pH values it reports at the temperatures specified therein, without any inference, conversion, or extrapolation from pH values measured at other temperatures.” [Remarks 1/21/2026, Page 7, Paragraph 5]
Applicant’s own specification explicitly asserts that pH measured at different temperatures are interchangeable (i.e., cannot be correlated or converted).
“The pH of Tris is temperature-dependent. At low temperatures, the pH of Tris is higher than at higher temperatures. For example, if a Tris buffer has a pH of 8.26 at 5° C., the Tris buffer will have a pH of 7.7 at 25° C. and a pH of 7.4 at 37° C. Storage of an ultrasound contrast agent is preferably done in a refrigerated space, i.e. at a temperature of approx. 3-6° C., which helps maintain the physical and chemical stability of the ultrasound contrast agent.” [PGPUB US 2022/0096666 A1, 0037]
“…Sonazoid having a bulk pH of 7.5 at 5° C. (corresponding to about pH 7 at room temperature since the pH of Tris is temperature dependent, as described elsewhere herein)… Sonazoid having a bulk pH of 8.5 at 5° C. (corresponding to about pH 8 at room temperature)…” [PGPUB US 2022/0096666 A1, 0094]
Moreover, a POSITA would be able to evaluate the cited art without any inference, conversion, or extrapolation from pH values measured at other temperatures because Sigvardsson discloses how to convert TRIS buffer pH across temperatures.
Applicant asserts the following:
“Thus, the references address different technical problems (injectable ultrasound contrast vs. organ preservation), operate in different physicochemical environments (dynamic insonation vs. static perfusion), and cannot reasonably be combined without impermissible hindsight.” [Remarks 1/21/2026, Page 8, Paragraph 4]
“While Dyvik teaches that water-soluble amine buffers such as TRIS, diethanolamine, and triethanolamine may reduce hydrolysis in bulk phospholipid systems, its teachings are anchored in broad buffer concentrations of 2-200 mM and pH 6.0-9.5 at 15 °C, and do not relate to the narrow 5-10 mM range or the alkaline 8.75-9.25 at 5 °C window required by claim 11. Although microbubbles are mentioned among various formulation types, Dyvik's buffer teachings address bulk phospholipid stability and autoclave behavior, not phospholipid-stabilized perfluorocarbon microbubble dispersions, and provide no guidance on gas-lipid interfacial chemistry, refrigerated microbubble stability, or microbubble median size and concentration.” [Remarks 1/21/2026, Page 11, Paragraph 2]
A reference is analogous art to the claimed invention if: (1) the reference is from the same field of endeavor as the claimed invention (even if it addresses a different problem); or (2) the reference is reasonably pertinent to the problem faced by the inventor (even if it is not in the same field of endeavor as the claimed invention). MPEP 2141.01(a). Accordingly, since the claimed invention is drawn to a dispersion that uses a TRIS buffer system and “Sigvardsson teaches maintaining pH at 7.0-7.8 at 25 °C using TRIS and notes only a modest increase of approximately +0.2 pH units when cooled to 5 °C,” then Sgivardson is a reference that is reasonably pertinent to the problem faced by the inventor. Furthermore, since the claimed invention is drawn to a phospholipid-stabilized microbubble dispersion, and “Dyvik's buffer teachings address bulk phospholipid stability” and “microbubbles are mentioned,” then Dyvik is a reference that is reasonably pertinent to the problem faced by the inventor.
Most importantly, “In order for a reference to be proper for use in an obviousness rejection under 35 U.S.C. 103, the reference must be analogous art to the claimed invention.” MPEP 2141.01(a). References need not be analogous to each other.
Applicant asserts “However, Dyvik teaches broad bulk solution concentration ranges of 2-200 mM and pH values of 6.0-9.5 at 15 °C, not 8.75-9.25 at 5 °C. Dyvik provides no suggestion to select only 5-10 mM of TRIS, diethanolamine, glycine, or triethanolamine for use in a phospholipid-stabilized microbubble dispersion, let alone to reach the narrow claimed alkaline pH at 5 °C.” [Remarks 1/21/2026, Page 10, Paragraph 3]
In the case where the claimed ranges "overlap or lie inside ranges disclosed by the prior art" a prima facie case of obviousness exists. MPEP 2144.05(I). Therefore, a POSITA need not select “only 5-10 mM of TRIS, diethanolamine, glycine, or triethanolamine for use in a phospholipid-stabilized microbubble dispersion.”
Furthermore, the pH of TRIS buffer is known in the art to be temperature dependent. This is not a property of TRIS buffer discovered by the Applicant. Accordingly, a POSITA would understand a pH of about 6.0 to 9.5 at 15°C is equivalent to a pH of about 8.5 to 9.8 at 5°C. Applicant’s own specification explicitly acknowledges and relies upon the temperature-pH dependence of TRIS buffer as an advantage of the claimed invention. Applicant cannot simultaneously rely on the well understood relationship of TRIS buffer as a feature of their invention while arguing that a POSITA would not understand or apply that same relationship when evaluating the prior art.
Applicant asserts the following:
“The Examiner's attempt to rely on Tris temperature-dependence is similarly unavailing. Dyvik reports pH only at 15 °C for broad buffer concentrations and provides no teaching on pH at 5 °C, no disclosure of 5-10 mM TRIS, and no basis to infer that such low concentrations would yield a bulk pH of 8.75-9.25 in a microbubble system.” [Remarks 1/21/2026, Page 11, Paragraph 3]
“Even accepting Dyvik's general hydrolysis-reduction teaching, nothing in the cited art suggests selecting TRIS, diethanolamine, glycine, or triethanolamine at 5-10 mM to achieve 8.75-9.25 at 5 °C, nor that such conditions would stabilize microbubble median size (1-6 µm) or target concentration (6-10 µL/mL) after refrigerated storage (~5 °C) at which the claimed pH is defined.” [Remarks 1/21/2026, Page 11, Paragraph 3]
The pH of TRIS buffer is known in the art to be temperature dependent. This is not a property of TRIS buffer discovered by the Applicant. Accordingly, a POSITA would understand a pH of about 6.0 to 9.5 at 15°C is equivalent to a pH of about 8.5 to 9.8 at 5°C. Applicant’s own specification explicitly acknowledges and relies upon the temperature-pH dependence of TRIS buffer as an advantage of the claimed invention. Applicant cannot simultaneously rely on the well understood relationship of TRIS buffer as a feature of their invention while arguing that a POSITA would not understand or apply that same relationship when evaluating the prior art.
Applicant asserts “Buffer behavior in bulk aqueous phases cannot be applied to colloidal microbubble dispersions, where curvature, charge screening, and gas-lipid interactions materially alter pH microenvironments and stability.” [Remarks 1/21/2026, Page 11, Paragraph 3]
Arguments presented by applicant cannot take the place of evidence in the record. MPEP 2145(I). Applicant has not demonstrated that curvature, charge screening, and gas-lipid interactions materially alter pH microenvironments and stability in the present case. Still, Applicant is encouraged to provide evidence demonstrating that these factors materially alter buffer behavior in colloidal microbubble dispersions such that a POSITA would therefore consider the buffer teachings disclosed by Dyvik inapplicable to the claimed invention.
Applicant asserts “Microbubbles with a phosphatidylserine membrane entrapping perfluorobutane gas are not equivalent to a phospholipid alone. The stability of phospholipids in bulk solution does not predict the stability of a phosphatidyl membrane surrounding a gas core. The gas-lipid interface introduces unique stresses, curvature effects, and ionic interactions absent in bulk phospholipid systems. Therefore, prior art teachings on phospholipid stability cannot reasonably be extrapolated to predict the claimed microbubble stability under the specific conditions of pH 8.9- 9.1 at 5 °C with the recited buffers at 5-10 mM. This structural and functional distinction underpins the unexpected results observed in maintaining microbubble integrity and concentration under the refrigerated storage conditions (~5 °C) at which the claimed pH is defined.” [Remarks 1/21/2026, Page 12, Paragraph 2]
“In determining the differences between the prior art and the claims, the question under 35 U.S.C. 103 is not whether the differences themselves would have been obvious, but whether the claimed invention as a whole would have been obvious.” MPEP 2141.02(I). Applicant suggests that the prior are teachings cannot reasonably be extrapolated under the specific claimed conditions, as if a POSITA would recognize the prior art teachings are broadly applicable except under these precise conditions. This reasoning is unsupported.
Additionally, Applicant repeatedly uses the term “predict.” Conclusive proof of efficacy is not required to show a reasonable expectation of success. MPEP 2143.02(I). A POSITA need not guarantee that the claimed microbubble stability can be achieved under the claimed conditions. The prior art teachings on phospholipid stability provide the requisite degree of predictability required to establish a prima facie case of obviousness.
Moreover, Applicant’s allegations of unexpected results are not persuasive for the following reasons:
“Any differences between the claimed invention and the prior art may be expected to result in some differences in properties. The issue is whether the properties differ to such an extent that the difference is really unexpected.” MPEP 716.02.
Applicant’s specification states:
“Literature data relating to liposome dispersions suggest that phospholipid hydrolysis is influenced by pH (Grit et al, Biochim. Biophys. Acta, 1167, 49-55, 1993). However, buffers that are used with liposomes are not necessarily compatible with microbubbles and stability data obtained with liposomes are not necessarily transferable to phospholipid-stabilised microbubbles, since phospholipid-stabilised microbubbles are different from liposomes in several ways.” [PGPUB US 2022/0096666 A1, 0092]
Accordingly, Applicant’s own specification acknowledges that pH influences phospholipid stability in liposomes, and this teaching could extend to the claimed phospholipid-stabilized microbubbles. Applicant was motivated to investigate this hypothesis and arrived at the conclusion that pH also influences phospholipid stability in phospholipid-stabilized microbubbles. This does not constitute an unexpected result, as Applicant acknowledged that the result may or may not occur. "Expected beneficial results are evidence of obviousness of a claimed invention, just as unexpected results are evidence of unobviousness thereof." MPEP 716.02(c)(II). Therefore, Applicant has not demonstrated that the observed stability differs to such an extent that it is truly unexpected.
“Evidence of unexpected results must be weighed against evidence supporting prima facie obviousness in making a final determination of the obviousness of the claimed invention.” MPEP 716.02(c)(I).
“Where the unexpected properties of a claimed invention are not shown to have a significance equal to or greater than the expected properties, the evidence of unexpected properties may not be sufficient to rebut the evidence of obviousness.” MPEP 716.02(c)(I).
The evidence “must compare the claimed subject matter with the closest prior art to be effective to rebut a prima facie case of obviousness. MPEP 716.02(e)
Applicant has not compared the claimed invention with the closest prior art. One cannot assert that the claimed invention achieves a result that the prior art would not be expected to achieve without first establishing what result the prior art is expected to achieve. Therefore, the evidence provided by the Applicant is not sufficient to rebut the prima facie case of obviousness of record.
“Whether the unexpected results are the result of unexpectedly improved results or a property not taught by the prior art, the "objective evidence of nonobviousness must be commensurate in scope with the claims which the evidence is offered to support." In other words, the showing of unexpected results must be reviewed to see if the results occur over the entire claimed range.” MPEP 716.02(d)
The data compares two test dispersions:
(1) one buffered aqueous dispersion of Sonazoid having a bulk pH of 7.5 at 5° C. (corresponding to about pH 7 at room temperature since the pH of Tris is temperature dependent, as described elsewhere herein), and
(2) one buffered aqueous dispersion of Sonazoid having a bulk pH of 8.5 at 5° C. (corresponding to about pH 8 at room temperature).
5 mM TRIS buffer was used to control and stabilize the pH of both dispersions. FIG. 2 shows the degree of degradation of phospholipids due to hydrolysis in the samples. FIG. 3 shows the volume concentration of the microbubbles during storage at 5° C. up to 6 months.
Notably, the data is not drawn to dispersions with a pH of 8.75 to 10.0 when measured at 5°C, dispersions prepared with 5 mM to 10 mM diethanolamine, glycine, or triethanolamine, and/or dispersions prepared with a concentration other than 5 mM TRIS buffer. Therefore, the data does not contemplate the specific conditions of pH 8.9-9.1 at 5 °C (or 8.75-9.25) with the recited buffers at 5-10 mM, let alone show unexpectedly superior results under these conditions.
Conclusion
Any inquiry concerning this communication or earlier communications from the examiner should be directed to KAILA A CRAIG whose telephone number is (703)756-4540. The examiner can normally be reached Monday-Friday 0800-1600.
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/K.A.C./Examiner, Art Unit 1618
/Michael G. Hartley/Supervisory Patent Examiner, Art Unit 1618
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