Compositions for chemoembolization and methods of treatment using same

Abstract

The present disclosure relates, inter alia, to improved treatment of solid tumors using embolic polymer microspheres, and to embolic polymer microspheres comprising a polymer and an inhibitor of poly ADP ribose polymerase enzyme (PARP inhibitor), wherein the PARP inhibitor is retained within the polymer microsphere and is elutable from the microsphere in an aqueous medium, and to methods of loading the embolic polymer microspheres.

Description

[Technical field]

[0001] The present disclosure relates, inter alia, to improved treatment of solid tumors using embolic microspheres, methods for loading embolic microspheres, and drug-loaded embolic microspheres. [Background technology]

[0002] Poly(ADP-ribose) polymerases (PARPs) are involved in DNA repair. They are activated by single- and double-strand breaks in DNA and play a role in the base excision repair pathway. PARP inhibitors are currently approved (FDA) for ovarian, fallopian tube, primary peritoneal, and breast cancer, but their efficacy in other tumors has been disappointing (see, e.g., Zhang et al., Hepatology (2012) 55(6):1840-1851 and Gabrielson et al., Cancer Chemother. Pharmacol. (2015) 76:1073-1079). PARP inhibitors have demonstrated efficacy against hepatocellular carcinoma (HCC) cell lines in vitro, but have proven less effective clinically.

[0003] Certain tumors may be amenable to treatment by embolization procedures, in which an embolic material, such as a microsphere suspension, is introduced into a blood vessel that feeds the tumor, where it lodges and causes an embolism that cuts off the blood supply to the local tissue. This approach is known as transarterial embolization, or TAE. In one approach, drugs may be incorporated into the embolic material and released into the tissue surrounding the embolization. This approach is known as transarterial chemoembolization, or TACE. Embolic microspheres have been prepared from a variety of biocompatible materials, including both natural and synthetic polymers.

[0004] During TAE, tissue embolization leads to ischemia and local tissue necrosis, which has been shown in some cases to be associated with the proliferation of tumor antigen-specific T cells. For example, Lakshmana et al. (J. Immunol. (2017) 178(3):1914-1922) stated that embolization is associated with the proliferation of peripheral alpha-fetoprotein (AFP)-specific CD4-positive T cells, and that this cell proliferation is associated with the induction of tumor necrosis and ameliorative effects.

[0005] Tumor antigens recognized by T cells are thought to originate from two main groups of proteins. First, non-mutated proteins to which T cell tolerance is incomplete or de novo induced. Second, tumor-specific antigens resulting from somatic gene mutations in the tumor genome, these are the so-called neoantigens. Neoantigens are thought to arise when such somatic gene mutations are inappropriately corrected by a malfunction of the DNA damage repair process, which is common in tumor cells. Some tumor types appear to carry a large number of such somatic gene mutations. In HCC, for example, the number of such mutations in individually analyzed tumors ranged from less than 1 to more than 10 per megabase (see Schumacher and Schreiber, Science (2015) 348, 69-74). Nevertheless, in some cancers, at least, there appear to be relatively few mutations that produce neoantigens for which CD4+ or CD8+ T cell responsiveness can be detected. [Prior art documents] [Non-patent literature]

[0006] [Non-Patent Document 1] Zhang et al, Hepatology (2012)55(6):1840-1851 [Non-Patent Document 2] Gabrielson et al, Cancer Chemother.Pharmacol.(2015)76:1073-1079 [Non-Patent Document 3] J. Immunol.(2017)178(3):1914-1922 [Non-Patent Document 4] Schumacher and Schreiber, Science (2015) 348, 69-74 Summary of the Invention

[0007] The inventors believe that localized delivery of PARP inhibitors to tumors in combination with the generation of embolism, such as induced by delivery of a microsphere suspension, may provide potential for improving tumor response to the PARP inhibitor (e.g., but not limited to, reduction in tumor size or improvement in overall survival), thereby providing improved treatment of tumors or patients.

[0008] The inventors further believe that enhanced DNA damage, in combination with the presence of high local concentrations of PARP inhibitors, may open the door to increased potential for neoantigen production. The inventors further believe that there is a possibility that T cell responses to tumors (e.g., liver tumors, including HCC) may be enhanced by localized delivery of PARP inhibitors such as olaparib, and such enhanced T cell responses may lead to improved treatment of tumors. Furthermore, this response may be augmented by additional treatments that lead to DNA damage, such as radiation therapy, and / or may be further exploited by combining the localized delivery of PARP inhibitors with one or more immune checkpoint inhibitors (with or without additional DNA damage promoting agents).

[0009] In various aspects, the present disclosure relates to polymeric microspheres comprising a polymer and a PARP inhibitor, wherein the PARP inhibitor is retained within the polymeric microsphere and is elutable from the microsphere in an aqueous medium.

[0010] In some embodiments, at least a portion of the PARP inhibitor is retained within the microsphere by ionic interactions between the PARP inhibitor and the polymer and / or is physically entrapped within the polymer microsphere.

[0011] In some embodiments, such as may be used in combination with the preceding aspects and embodiments, the PARP inhibitor is elutable from the polymeric microspheres in an aqueous medium, such as phosphate buffered saline or water.

[0012] In some embodiments that may be used in combination with the preceding aspects and embodiments, the PARP inhibitor may be selected from olaparib (AZD-2281), rucaparib (PF-01367338), niraparib (MK-4827), talazoparib (BMN-673), veliparib (ABT-888), CEP9722, E7016, BGB-290, and 3-aminobenzamide.

[0013] In some embodiments, such as may be used in combination with the preceding aspects and embodiments, the polymer may have one or a combination of two or more of the following characteristics: (a) the polymer may be anionically charged at pH 7.4; (b) the polymer may be crosslinked; (c) the polymer may be in the form of a hydrogel; or (d) the polymer may be biodegradable or bioerodible.

[0014] In some embodiments, such as may be used in combination with the preceding aspects and embodiments, the polymer may be a polyester, a polysaccharide, or a biodegradable or biodegradable but non-biodegradable / bioerodible PVA polymer. For example, the polymer may be a biodegradable or bioerodible crosslinked PVA polymer or PVA copolymer, or the polymer may be poly(lactic-co-glycolic acid) (PLGA). In some of these embodiments, the ratio of lactic acid units to glycolic acid units in the PLGA is between 50:50 and 10:90.

[0015] In some embodiments that may be used in combination with the preceding aspects and embodiments, the polymer microsphere is a hydrogel polymer microsphere comprising a cross-linked polyvinyl alcohol polymer and a PARP inhibitor, where the cross-linked polyvinyl alcohol polymer has a negative charge at pH 7.4, and the PARP inhibitor is retained within the polymer microsphere and is elutable from the polymer microsphere in an aqueous medium. In some of these embodiments, the PARP inhibitor may be in particulate form within the polymer microsphere.

[0016] In some embodiments, such as those that may be used in combination with the preceding aspects and embodiments, a polymeric microsphere comprises poly(lactic-co-glycolic acid) (PLGA) and a PARP inhibitor, wherein the PARP inhibitor is retained within the polymeric microsphere and is elutable from the microsphere in an aqueous medium (e.g., based at least in part on the biodegradability or bioerodibility of the polymeric microsphere).

[0017] In various additional aspects, the present disclosure relates to a medical composition comprising a plurality of polymeric microspheres as according to any of the above aspects or embodiments. In some embodiments, the medical composition is in the form of a lyophilized powder comprising the polymeric microspheres. In some of these embodiments, the lyophilized powder further comprises a polyol protectant.

[0018] In some embodiments, the medical composition further comprises an aqueous solution in which the polymeric microspheres are suspended as hydrated polymeric microspheres.

[0019] In some embodiments, the medical composition comprises 0.1 to 50 mg of a PARP inhibitor per mL of hydrated polymer microspheres. In some embodiments, which may be used in combination with the preceding aspects and embodiments, the medical composition is an injectable composition.

[0020] In various further aspects, the present disclosure relates to a method for treating a patient having a solid tumor, the treatment comprising delivering a medical composition according to the preceding aspects and embodiments to the solid tumor, whereby the PARP inhibitor elutes from the polymer microspheres and into the tumor tissue.

[0021] In some embodiments, the composition is delivered to the tumor by local injection. In some embodiments, the composition is delivered to the tumor via one or more blood vessels that supply at least a portion of the tumor, and the polymeric microspheres lodge in the blood vessels and cause embolism, hi some of these embodiments, the composition is delivered to the tumor via a microcatheter.

[0022] In some embodiments, such as may be used in combination with the preceding aspects and embodiments, the treatment of the patient further comprises treatment with radiation therapy, which may be performed before, during, and / or after delivery of the medical composition. For example, radiation therapy may comprise external beam radiation therapy (EBRT), brachytherapy, or selective internal radiation therapy (SIRT), among others.

[0023] In some embodiments that may be used in combination with the preceding aspects and embodiments, treating a patient further comprises delivering one or more checkpoint inhibitors to a tumor. The one or more checkpoint inhibitors may be delivered locally to the tumor or systemically. The one or more checkpoint inhibitors may be delivered before, during, and / or after delivery of the medical composition.

[0024] In some embodiments, (a) the checkpoint inhibitor is selected from an inhibitor of binding of PD-1 to PD-L1, an inhibitor of binding of CTLA-4 to CD80 and / or CD86, an inhibitor of binding of LAG-3 to MHC class II, or an inhibitor of binding of TIGIT to CD112 and / or CD115; (b) the checkpoint inhibitor is selected from an antibody or antigen-binding fragment thereof that binds to PD-1, PD-L1, LAG-3, TIGIT, or CTLA-4; (c) the checkpoint inhibitor is selected from pembrolizumab, nivolumab, ipilimumab, atezolizumab, avelumab, tremelimumab, relatolimab, durvalumab; (d) the checkpoint inhibitor is selected from an antibody or antigen-binding fragment thereof that binds to TIM-3; or (e) the checkpoint inhibitor is selected from LY3321367, MBG453, and TSR-022.

[0025] In various additional aspects, the disclosure relates to a method of preparing hydrogel polymer microspheres having an encapsulated PARP inhibitor, the method comprising the steps of: (a) contacting dehydrated hydrogel polymer microspheres with a solvent solution comprising the PARP inhibitor dissolved in a first solvent, (b) recovering the microspheres produced in step (a), and (c) washing the recovered microspheres of step (b) with a second solvent, wherein the first solvent is an organic solvent suitable for dissolving the PARP inhibitor at a concentration of at least 10 mg / mL at 25° C., and the second solvent is a solvent in which the PARP inhibitor is soluble at less than 0.1 mg / mL at 25° C. In some of these embodiments, the PARP inhibitor is olaparib.

[0026] In some embodiments, the first solvent is an organic solvent. Examples of organic solvents include, for example, dimethylsulfoxide (DMSO), dimethylformamide (DMF), N-methyl-2-pyrrolidone (NMP), dimethylisosorbide (DMI), glycofurol, solketal, and combinations thereof, among others.

[0027] In some embodiments, the second solvent is an aqueous solvent, such as water, normal saline, or phosphate buffered saline. In various further aspects, the present disclosure relates to a PARP inhibitor for use in treating solid tumors, wherein the PARP inhibitor is provided in the form of a plurality of polymeric microspheres comprising the PARP inhibitor and a polymer, the polymeric microspheres including a polymeric microsphere according to any of the preceding aspects, and wherein the PARP inhibitor is retained within the polymeric microsphere and is elutable from the microsphere in an aqueous medium.

[0028] In various further aspects, the disclosure relates to the use of a PARP inhibitor in the manufacture of a therapeutic agent for the treatment of a solid tumor, wherein the PARP inhibitor is in the form of a plurality of polymeric microspheres comprising the PARP inhibitor and a polymer, the polymeric microspheres including a polymeric microsphere according to any of the preceding aspects, and wherein the PARP inhibitor is retained within the polymeric microspheres and is elutable from the microspheres in an aqueous medium. [Brief description of the drawings]

[0029] [Figure 1] FIG. 1 shows the size distribution of bland microspheres as a control and encapsulated microspheres according to an embodiment of the present disclosure. [Diagram 2] FIG. 2 shows the elution profile of olaparib-loaded microspheres in a constant flow of warm saline (flow rate 1.7 mL / min, 37° C.) in terms of eluted olaparib concentration versus time, according to an embodiment of the present disclosure. [Diagram 3] FIG. 3 shows the elution profile of olaparib-loaded microspheres in a constant flow of warm saline (flow rate 1.7 mL / min, 37° C.) in terms of total olaparib dose eluted versus time, according to an embodiment of the present disclosure. [Figure 4]FIG. 4 shows the dissolution profile of olaparib-loaded microspheres according to an embodiment of the present disclosure, as total dose of olaparib dissolved versus time under pseudo-sink conditions at 37° C. [Diagram 5] FIG. 5 shows the dissolution profile of olaparib-loaded PLGA microspheres in PBS / tween 20 at pH 7.4 at 37° C. as total drug release versus time according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0030] In a first aspect, the present disclosure provides a polymeric microsphere comprising an inhibitor of poly ADP-ribose polymerase enzyme (PARP), the PARP inhibitor being retained within the polymeric microsphere and elutable from the microsphere in an aqueous medium.

[0031] Advantageously, the PARP inhibitors are not typically covalently bound to the polymer of the microspheres and are freely elutable from the microspheres in aqueous media, particularly in ionic aqueous media such as plasma, common saline, or common phosphate buffered saline (0.01 M phosphate buffered saline (0.138 M NaCl; 0.0027 M KCl), pH 7.4).

[0032] The PARP inhibitor may be retained within the microsphere by one or more non-covalent interactions (e.g., van der Waals forces, hydrophobic interactions, and / or electrostatic interactions, including ionic interactions (also referred to as charge-charge interactions or electrostatic interactions), charge-dipole interactions, and dipole-dipole interactions, including hydrogen bonding) with the polymer and / or physical hooks within the microsphere. In various embodiments, the drug is distributed throughout the microsphere matrix, but may be present in lesser amounts near the surface than elsewhere due to the washing process during preparation. The drug may, for example, be entrapped within the polymer microsphere (e.g., as a powder and / or in crystalline or amorphous form) or may be retained within the microsphere by one or more non-covalent interactions with the polymer, e.g., by ionic interactions, particularly if the polymer and drug contain charged components.

[0033] The drug may be associated with the polymer microsphere in a number of ways, for example, by physical entrapment when the drug is mixed with the polymer during manufacture of the microsphere (e.g., when the polymer is in the form of a monolithic biodegradable or bioerodible polymer matrix such as a poly(lactic-co-glycolic acid) (PLGA) matrix), or the drug may be precipitated and / or crystallized within the polymer matrix of a preformed microsphere during the drug encapsulation process (e.g., when the drug is encapsulated in a hydrogel polymer such as cross-linked PVA (see, e.g., WO2007 / 090897A1 and WO2007 / 085615A1).

[0034] Retaining drugs within polymeric microspheres by ionic interactions is particularly useful when the drug carries, or can be induced to carry, a charge, for example by exposing the drug to an appropriately acidic or basic solution and inducing it to form a salt. Such an encapsulation mechanism is useful when the polymeric microsphere carries a charge at biological pH (pH 7.4). Drug encapsulation by precipitation and / or crystallization is useful when the drug has low stability in water.

[0035] In use, once the microspheres have been delivered, the drug will be released from the microspheres into the surrounding medium (tissue or blood), for example by bioerosion or biodegradation of the polymers forming the microspheres, or by diffusion of the drug from the polymer matrix of the microspheres, or a combination of both. For the avoidance of doubt, the term "elution" is herein deemed to encompass each or both of these mechanisms of release. Drug release may be demonstrated at biological pH (7.4) and / or in ionic media, typically in common phosphate buffered saline.

[0036] The polymer(s) forming the microspheres may be natural, synthetic, or a hybrid of natural and synthetic polymers. Any polymer suitable for retaining a drug within the polymeric microsphere in such a way that the drug is elutable from the microsphere in an aqueous medium (such as common phosphate buffered saline) may be used.

[0037] Suitable natural polymers include proteins (such as gelatin), polysaccharides (starchs, chitosans, glycogens, celluloses (such as methylcellulose, carboxymethylcellulose, or hydroxyethylcellulose)), alginic acid, and polysaccharide gums (e.g., carrageenan, guar gum, xanthan gum, gellan gum, locust bean gum, and gum arabic).

[0038] Suitable synthetic polymers include acrylates, acrylamides, acrylics, acetals, allyls, synthetic polysaccharides, methacrylates, polyamides, polycarbonates, polyesters, polyethers, polyimides, polyolefins, polyphosphates, polyurethanes, silicones, styrenes, and vinyls, or combinations and / or copolymers thereof. In some embodiments, the polymer is a homopolymer or copolymer comprising one or more monomers selected from vinyl alcohol, ethylene glycol (ethylene oxide), propylene glycol (propylene oxide), acrylates, methacrylates, acrylamides, or methacrylamides.

[0039] In some embodiments, the polymer may be a natural hydrophilic polymer and / or a synthetic hydrophilic polymer for improved biocompatibility. Suitable hydrophilic polymers include polyvinyl alcohol, acrylates and methacrylates and their salts (e.g., polyacrylic acid, polymethacrylic acid, and polymethylmethacrylate), carboxymethylcellulose, hydroxyethylcellulose, polyvinylpyrrolidone, polyethylene glycol (PEG), PEG-methacrylate, PEG-methylmethacrylate, polyacrylamide (e.g., N,N-methylene-bis-acrylamide or tris(hydroxymethyl)methacrylamide), or natural polymers (e.g., proteins or polysaccharides, such as those described herein or elsewhere, or mixtures or copolymers containing at least one of the foregoing).

[0040] In some embodiments, the hydrophilic polymer comprises or is a polyhydroxylated polymer, i.e., a polymer that comprises repeating units with one or more pendant hydroxy groups. Preferred polyhydroxylated polymers include polymers containing polyol esters of acrylates and methacrylates, such as poly(hydroxyalkyl acrylates) and poly(hydroxyalkyl methacrylates), such as poly(hydroxyethyl methacrylate); poly(hydroxyalkyl acrylamides) and poly(hydroxyalkyl methacrylamides), such as tris(hydroxymethyl) methacrylamide; poly(PEG acrylates) and poly(PEG methacrylates); polymers containing vinyl alcohol, such as poly(vinyl alcohol) polymers or (ethylene vinyl alcohol) copolymers; and polysaccharides.

[0041] In further embodiments, the hydrophilic polymer may be a polycarboxylic acid polymer, i.e., a polymer that includes repeating units with one or more pendant carboxy groups. These polymers include, for example, polyacrylic acid, polymethacrylic acid, and copolymers thereof and their salts (Group 1 metal salts or Group 2 metal salts, such as sodium, potassium, calcium, or magnesium salts, etc.).

[0042] In one embodiment, the hydrophilic polymer is in the form of a hydrogel, which is either covalently or non-covalently crosslinked. These polymers are water-swellable but poorly soluble in water. The polymers may contain more than 50% by weight of water, for example up to 99% by weight. Such polymers may contain, for example, 60% to 98% by weight of water.

[0043] In some embodiments, the polymer can be a biodegradable or bioerodible polymer, including, but not limited to, polyesters and polysaccharides (e.g., such as those mentioned elsewhere herein).

[0044] Biodegradable and / or bioerodible polymers include, but are not limited to, polylactic acids such as polylactic acid (PLA), polyglycolic acids such as polyglycolic acid (PLG), polyhydroxyalkanoates such as polyhydroxybutyrate or polyhydroxyvalerate, poly-ε-caprolactone, and copolymers of the above, such as poly(lactic acid-co-glycolic acid) (PLGA) or poly(3-hydroxybutyrate-co-3-hydroxyvalerate), among others. In one preferred embodiment, the biodegradable polymer is PLGA.

[0045] Further examples of biodegradable or bioerodible polymers include polyvinyl alcohol (PVA) polymers crosslinked with crosslinkers containing disulfide bonds (e.g., those described in WO 2012 / 101455, incorporated herein by reference), and polymers in which the PVA backbone is C 3 -C 8 A PVA polymer crosslinked with a diacid (such as alpha-ketoglutaric acid) through an ester bond to the hydroxy groups of the PVA backbone (e.g., as described in WO2020 / 003152, which is incorporated herein by reference).

[0046] In some embodiments, the polymer may include functional groups that are charged at pH 7.4. Such functional groups may have a net positive charge or a net negative charge, and thus may reversibly bind compounds with opposite net charges at biological pH (pH 7.4). A variety of charged functional groups may be used, including sulfonate, phosphate, ammonium, phosphonium, and carboxylate groups; in some embodiments, carboxylate and sulfonate groups are preferred. Anionically charged polymers at pH 7.4 are preferred. The charged polymer at pH 7.4 may be selected from a range of, for example, natural and / or synthetic polymers, hydrophilic and / or hydrophobic polymers, biostable polymers, and / or biodegradable polymers, including those mentioned above.

[0047] In some embodiments, the polymers of the polymeric microspheres can be crosslinked. Crosslinking can be based on covalent crosslinking, non-covalent crosslinking, or a combination of both. Non-covalent crosslinking includes physical crosslinking, for example, due to the entanglement of polymer chains or due to the presence of crystalline regions. Non-covalent crosslinking also includes ionic crosslinking. Ionic crosslinking can occur when charged functional groups on a polymer are crosslinked by functional groups that carry an opposite charge. In some cases, this phenomenon can be accomplished with divalent metal ions or higher valent (e.g., trivalent) metal ions, such as calcium, magnesium, or barium, among others.

[0048] Covalent cross-linking can be achieved by any method suitable for covalently linking functional groups on different chains together. If cross-linking is achieved during the polymerization stage, this can be by incorporation of difunctional monomers during polymerization. Alternatively, or in addition, cross-linking can be achieved after polymerization, for example, by reaction with a difunctional species capable of reacting with functional groups on the preferred polymer (e.g., particularly hydroxy or carboxy groups).

[0049] The crosslinker may also incorporate degradable regions (see, for example, WO 2001 / 68720) either within the crosslinker or at the end of the crosslinker (e.g., an ester bond (e.g., as described in WO 2020 / 003152)).

[0050] In one embodiment, the polymer comprises polyvinyl alcohol (PVA), for example, homopolymers and copolymers of PVA, particularly such polymers that are crosslinked with PVA moieties and charged with PVA moieties at pH 7.4.

[0051] One type of PVA polymer is a polyvinyl alcohol macromer, which has one or more ethylenically unsaturated pendant groups per molecule, which are formed by the reaction of PVA with an ethylenically unsaturated monomer. A PVA macromer can be formed, for example, by providing a PVA polymer with pendant ethylenically unsaturated groups, such as pendant vinyl groups or pendant acrylic groups. A pendant acrylic group can be provided, for example, by reacting acrylic acid or methacrylic acid with PVA to form an ester bond through some of its hydroxyl groups. Compounds having ethylenically unsaturated functional groups that can be bonded to polyvinyl alcohol are described, for example, in US 4,978,713, US 5,508,317, and US 5,583,163. In a preferred embodiment, the macromer comprises a polyvinyl alcohol backbone to which (alk)acrylaminoalkyl moieties are attached. One example of such a polymer includes PVA-N-acryloylaminoacetaldehyde dimethyl acetal (NAAADA) macromer, also known as Nelficon-B or acrylamide-PVA.

[0052] In one preferred embodiment, the macromer may be reacted with an ethylenically unsaturated monomer, optionally carrying a positive or negative charge, such as 2-acrylamido-2-methylpropanesulfonic acid (AMPS), in order to crosslink the polymer.

[0053] Such polymers and methods for making them are described in WO0168720 and WO04071495. Microspheres of such polymers are commercially available as DC Bead®, LC Bead®, Bead Block® or their radiopaque versions DC Bead® LUMI or LC Bead® LUMI (Biocompatibles, UK, Ltd).

[0054] Microspheres can be prepared in any desired size range, however, sizes ranging from about 10 μm (microns) to 2000 μm are usually preferred. Smaller sizes may pass through the capillary system and remain elsewhere beyond the embolization site. In most applications, a small size range of microspheres will be desirable to reduce aggregation during delivery and provide predictable embolization. Microspheres can be sized before or after encapsulation. For example, in the unlikely event that the encapsulation process changes the size of the unencapsulated microspheres (also referred to as native or bland), the microspheres are sized after encapsulation to provide a more accurate size range. Typically, microspheres have an average diameter size range of 10-2000 μm, more typically 20-1500 μm, and even more typically 40-900 μm. Microsphere preparations typically yield microspheres in a size range that is suited to the planned treatment, e.g., 100-300 microns, 300-500 microns, 500-700 microns, or 700-900 microns. For certain procedures, microspheres in the size range of 40-75 microns, 40-90 microns, or 70-150 microns are particularly useful, since smaller microspheres tend to reach deeper into the vascular bed.

[0055] The hydrogel microspheres may be provided in a dry form. If the microspheres are provided in a dry form, it is advantageous to incorporate a pharmacologically acceptable water-soluble polyol into the polymer before the drying step. This is particularly advantageous for hydrogels, since the water-soluble polyol protects the hydrogel matrix in the absence of water. Useful polyols are freely water-soluble sugars (such as monosaccharides or disaccharides) and sugar alcohols, such as glucose, sucrose, trehalose, mannitol and sorbitol.

[0056] The microspheres can be dried by any suitable process, however drying under vacuum, such as freeze-drying (lyophilization), has advantages since it allows the microspheres to be stored in a dry and reduced pressure state. Preferably, such microspheres have a moisture content of less than 1% wt / wt, more preferably less than 0.1% wt / wt. As described in WO2007 / 147902 (hereby incorporated by reference), storing under vacuum leads to improved rehydration. Typically, the pressure conditions under which dried microspheres are stored are less than 1 mBar (gauge pressure).

[0057] The microspheres may be imageable to aid in visualization during or after treatment. Imaging capabilities are preferably techniques including, but not limited to, ultrasound, x-ray, magnetic resonance imaging, paramagnetic resonance imaging, positron emission tomography (PET, etc.), or SPECT (single photon emission computed tomography). In various embodiments, imaging capabilities may be enhanced by including a suitable contrast agent within the microsphere or within any medium surrounding the microsphere.

[0058] In a preferred embodiment, the microspheres can be imaged by X-ray. This can be enhanced by incorporating radiopaque components into the microspheres as contrast agents, either covalently or non-covalently. Examples of non-covalently incorporated radiopaque components include particulate materials such as barium salts (e.g., see Thanoo et al J. Appl. Biomater. (1991) 2:67-72) or metals such as tantalum, or iodized oils such as Lipiodol® (e.g., EP1810698A1). The microspheres may contain covalently bound radiopaque components such as iodine or bromine (e.g., WO2015 / 033093) or bismuth (e.g., WO2018 / 093566). In one embodiment, the microspheres contain a radiopaque agent in the form of covalently bound iodine atoms. In one embodiment, such microspheres comprise PVA as described elsewhere herein, with the radiopaque agent covalently attached to the PVA backbone. Commercially available radiopaque microspheres with covalently attached iodine atoms include DC Bead Lumi® (Biocompatibles, UK, Ltd, Camberley, UK).

[0059] Poly ADP-ribose polymerase (PARP) is a family of proteins involved in many cellular processes, including DNA repair, genomic stability, and programmed cell death. This family includes PARP-1, PARP-2, and several other enzymes. Inhibitors of this enzyme are well known, and several are FDA approved and commercially available. Components for use in the microspheres of the present disclosure preferably inhibit one or more PARP family enzymes, and preferably inhibit either or both PARP-1 and PARP-2. Known PARP inhibitors include, for example, olaparib (AZD-2281), rucaparib (PF-01367338) commercially available as the camsylate salt, niraparib (MK-4827), talazoparib (BMN-673), veliparib (ABT-888), CEP9722, E7016 (GPI-21016), BGB-290, 2X-121, ABT-767, AZ-0108, JPI-547 (NOV1402), NMS-P118, NMS-P293, NT-125. Others are believed to be in the development pipeline. In some embodiments, olaparib is preferred.

[0060] PARP inhibitors can be encapsulated in microspheres in a number of ways. The drug can be entrapped in the polymer by mixing with the polymer during manufacturing. Alternatively, the drug can be precipitated and / or crystallized within the polymer matrix. This approach is useful when the PARP inhibitor has low water solubility, e.g., <0.1 mg / mL in water at 25° C. Encapsulation can be achieved by contacting the microspheres with an organic solvent suitable for dissolving the PARP inhibitor, so that the microspheres absorb the solvent. This can be achieved either by washing the microspheres several times in the solvent to exchange any aqueous suspension medium, or by swelling the lyophilized microspheres in the solvent. The solvent-swollen microspheres are then contacted with a solvent solution of the PARP inhibitor (usually in the same solvent). This solvent for the PARP inhibitor is capable of dissolving the PARP inhibitor in an amount of typically at least 10 mg / mL at 25° C., preferably at least 20, 30, or 40 mg / mL at 25° C. Preferred are embodiments in which the drug is dissolved at more than 70 mg / mL at 25° C. The microspheres are then collected after a suitable equilibration time (e.g., 15 min to 1 h) and briefly washed (e.g., 0.5 min to 1 min) in a medium in which the drug can dissolve less than 0.1 mg / mL. An aqueous solvent is typically used for this purpose and may be, for example, common saline or water. The microspheres are then lyophilized. This encapsulation process is particularly useful for hydrogel microspheres and can be used whether the microspheres are ionically charged or not. The above-mentioned encapsulation process is suitable for example for olaparib.

[0061] If the PARP inhibitor has a net charge, the drug can be encapsulated in microspheres of the opposite net charge by contacting an aqueous solution of the drug with a suspension of the microspheres until the microspheres absorb the drug, a process that typically takes 5 minutes to an hour. The microspheres can then be recovered and lyophilized if necessary.

[0062] The amount of drug encapsulated in the microspheres can be controlled, for example, by varying the amount of drug or drug concentration in the encapsulation solution and / or by varying the number of available charged functional groups on the microsphere, depending on the encapsulation method used and the solubility and / or charge on the particular PARP inhibitor used. The drug concentration in the microspheres is desirably in the range of 0.1-100 mg / mL microspheres (fully swollen in normal saline), preferably 1-50 mg / mL microspheres.

[0063] The PARP inhibitor may be provided in the form of dry microspheres, as described above, which may be assembled into an aqueous composition (e.g., using water for injection or normal saline) before use, or may be in the form of microspheres in an aqueous composition (e.g., water for injection or normal saline, etc.). A contrast agent may be added prior to injection to enhance visualization during administration. Such compositions represent further aspects of the present disclosure.

[0064] To visualize the composition during delivery and / or to adjust the density of the composition, the composition may further comprise an imaging agent suitable for use in imaging modalities including, but not limited to, X-ray, ultrasound, PET, SPET, magnetic resonance imaging, paranormal magnetic resonance imaging, nuclear medicine techniques, etc. This may be, for example, an iodine-containing imaging agent, which may be ionic or non-ionic, but is preferably non-ionic.

[0065] In a further aspect, the disclosure provides a method of treating a patient having a solid tumor, the method comprising delivering to the solid tumor a composition comprising a plurality of polymeric microspheres, e.g., hydrophilic polymeric microspheres, comprising a PARP inhibitor, the PARP inhibitor being retained within the polymeric microspheres and elutable from the microspheres in an aqueous medium, the PARP inhibitor being eluted from the microspheres into the tumor tissue. Dosages range from 1 mg / day or less to 50 mg / day or more, in some embodiments, from 2.5 mg / day to 25 mg / day, and in some cases, for example, from 5 mg / day to 10 mg / day.

[0066] The treatments presented in this disclosure have broad applicability in solid tumors. A composition comprising microspheres may be delivered by a transarterial route in TACE, where the composition is delivered to the tumor via one or more blood vessels that supply at least a portion of the tumor, and the microspheres lodge in the blood vessels, resulting in embolism. Alternatively, or in addition, the microspheres may be delivered by direct injection into the tumor, for example, to form a drug depot within the tumor.

[0067] The method has a specific use in tumors, where a suitable microcatheter can be placed to selectively deliver microspheres into the blood vessels supplying the tumor, such as the so-called "hypervascular tumors." Catheters useful for this purpose typically have an outer diameter (OD) in the range of 0.8-0.9 mm (2.4-2.8 Fr). Specific tumors include liver tumors, such as hepatocellular carcinoma (HCC), and neuroendocrine tumors (NETs) in liver and prostate tumors and metastases from colorectal cancer (mCRC). Other tumors include kidney tumors, adrenal tumors, brain tumors such as gliomas, lung tumors, pancreatic tumors, head and neck tumors, ovarian tumors, breast tumors, and testicular tumors.

[0068] Depending on the size and / or vascularity of the tumor, at least about 0.1 mL, preferably at least about 0.5 mL, of the composition containing the microspheres is delivered to the tumor. The maximum amount is usually dependent, and in the case of TACE treatment, on the size of the tumor, its vascularity and the volume of blood vessels available for embolization. Usually, the volume of the microsphere composition delivered is between about 0.1 mL and about 5 mL, more typically between about 0.2 mL and about 3 mL. Once the first vascular bed is embolized, the microsphere composition can be delivered to a second blood vessel that supplies blood to the tumor, etc. The figures presented relate to the total volume of the microsphere composition delivered to the tumor.

[0069] The treatment of the present application further includes treatment with radiation therapy, applied as external beam radiation therapy (EBRT) or selective internal radiation therapy (SIRT) or brachytherapy. The level of radiation used will depend on the sensitivity to damage, but will usually be in the range of 10-120 Gy. Radiation therapy may be administered before, during and / or after delivery of the microspheres.

[0070] The methods of the present application may further include treating the patient with one or more immune checkpoint inhibitors. These inhibitors may be delivered before, during, and / or after delivery of the microspheres. Furthermore, they may be delivered locally (i.e., within the tumor) or systemically. In one embodiment, the polymer further comprises a checkpoint inhibitor that is retained within the polymer microsphere and is elutable from the microsphere in an aqueous medium. Treatment with one or more checkpoint inhibitors may be performed in combination with radiation therapy.

[0071] Checkpoint inhibitors are well known, some currently approved for use and others in development. Checkpoint inhibitors may be selected from one or more of the following: inhibitors of PD-1 binding to PD-L1, inhibitors of CTLA-4 binding to CD-80 and / or CD86, inhibitors of LAG-3 binding to MHC-class 2 molecules and inhibitors of TIGIT binding to CD-112. Typically, the inhibitors will be selected from antibodies (particularly humanized antibodies or fully humanized monoclonal antibodies) or antigen-binding fragments thereof, which bind to PD-1, PDL-1, LAG-3, TIGIT or CTLA-4. These include, among others, pembrolizumab, nivolumab, ipilimumab, atezolizumab, avelumab, tremelimumab, the combination of leratolimab and durvalumab, etigilimab, domvanalimab, tiragolumab, vibostolimab, EOS-448, ASP837414, BMS-986207. Checkpoint inhibitors may also be selected from antibodies or antigen-binding fragments thereof that bind to TIM-3, such as LY3321367, MBG453, and TSR-022.

[0072] Checkpoint inhibitors are typically delivered according to the manufacturer's recommendations, which are typically in the range of 0.5-25 mg / kg, although as a guideline. for example, Pembrolizumab is administered at a dose of 1 to 3 mg / kg, preferably 2±0.5 mg / kg. Nivolumab is administered at a dose of 0.5 to 5 mg / kg, preferably 1 to 4 mg / kg. Ipilimumab is administered at a dose of 0.1 to 20 mg / kg IV, preferably 1 to 10 mg / kg Atezolizumab is administered at a dose of 0.5 to 2 mg / kg, preferably 1.5±0.5 mg / kg. Avelumab, 10±5mg / kg Tremelimumab is administered at a dose of 0.5 to 5 mg / kg, preferably 1±0.5 mg / kg. Durvalimumab is administered at a dose of 5 to 30 mg / kg, preferably 20±5 mg / kg. In a further embodiment of the present disclosure, a PARP inhibitor is presented for use in the treatment of solid tumors, wherein the PARP inhibitor is retained within a plurality of hydrophilic polymer microspheres and is elutable from the microspheres in an aqueous medium.

[0073] In a further embodiment of the present disclosure, there is provided the use of a PARP inhibitor in the manufacture of a therapeutic agent for the treatment of solid tumors, wherein the PARP inhibitor is retained within a plurality of hydrophilic polymer microspheres and is elutable from the microspheres in an aqueous medium.

[0074] Example 1: Encapsulation of Olaparib into PVA hydrogel microspheres The following examples use samples of DC Bead LUMI® (Biocompatibles, UK, Ltd) in various size ranges. The hydrogel microspheres contain negatively charged cross-linked PVA. The microspheres are radiopaque due to the properties of iodophenyl groups covalently attached to the PVA backbone.

[0075] 1 mL of hydrated microspheres (DC Bead LUMI®, size range 70-150 μm) were washed with DMSO (5 mL, 3 times) to replace the hydration medium. The volume of the microspheres increased with the DMSO washes but stabilized after the third wash. 2 mL of olaparib solution (120 mg / mL) dissolved in DMSO was mixed with the microspheres and equilibrated for 1 h. The olaparib solution was then removed and the microspheres were washed with saline (15 mL, 5 times) and sieved through a 40 μm cell strainer to remove drug particles. Finally, the washed microspheres were subjected to lyophilization overnight to obtain free-flowing microspheres. Table 1 shows the calculated encapsulated dose after DMSO extraction and HPLC analysis against an olaparib standard.

[0076] [Table 1]

[0077] Example 2: Encapsulation of olaparib into lyophilized PVA hydrogel microspheres. Five mL of hydrated microspheres (DC Microsphere LUMI®, size range 70-150 μm, Biocompatible, UK, Ltd) were lyophilized to remove water. The microspheres were mixed with 5 mL of DMSO-dissolved Olaparib solution (80 mg / mL) and roller mixed for 1 h. After removing the drug solution, the microspheres were washed with saline (50 mL, 3 times) and then dispensed into four vials (1.5 mL each vial). The microspheres were then lyophilized for 24 h to produce flowable microspheres. The encapsulation yield was determined according to Example 1. The residual drug in the solution was measured and the encapsulation yield was calculated as the ratio of the amount of drug encapsulated in the microspheres to the initial total amount of drug added. The results are shown in Table 2.

[0078] [Table 2]

[0079] Example 3: Bulk encapsulation process of Olaparib into PVA hydrogel microspheres 40 mL of wet DC Bead LUMI® (40-75 μM) was transferred to a Duran® bottle and excess encapsulation solution was removed. The microspheres were then washed twice in 150 mL of DMSO by agitating at 400 rpm on a plate shaker for 5 min. 40 mL of olaparib DMSO solution at 80 mg / mL was then added to the microsphere slurry, targeting a theoretical maximum encapsulation dose of 80 mg in 1 mL of microspheres. The encapsulation solution / microsphere mixture was agitated at 400 rpm on a plate shaker for 1 h. Once agitation was completed, excess encapsulation solution was removed. The encapsulated microspheres were then washed in 300 mL of 0.9% saline and agitated at 400 rpm for 5 min, after which the saline was removed. This step was repeated for a second saline wash. The encapsulated microspheres were dispensed into vials (1.5 mL each) and lyophilized. The lyophilized microspheres were then sterilized by gamma irradiation at an absorbed dose of 25 kGy.

[0080] The encapsulation efficiency of the microspheres was assessed using DMSO / saline extraction and analysis by HPLC, and the results are shown in Table 3. The average volume of the microspheres in the vials after lyophilization was found to be 0.79 mL.

[0081] [Table 3]

[0082] Reconstitution in water resulted in normal-appearing, smooth, spherical microspheres. The size distribution of control, bland, and encapsulated microspheres was determined using a microscope. The results are depicted in Figure 1, which compares the respective size histograms. After encapsulation with olaparib, the size distribution of the microspheres did not change significantly.

[0083] Example 4: Elution of Olaparib from Encapsulated Microspheres Flow-through method: The reconstituted olaparib-loaded microspheres of Example 3 were introduced into a flow-through system and the drug release was determined in warm saline at a constant flow rate (flow rate 1.7 mL / min, 37° C.) according to Swaine et al., EJPharm.Sci.(2016) 93, 351-359. The olaparib concentration in the column eluate was determined in situ in the flow cell at a wavelength of 279 nm by passing it through a UV-Vis spectrometer.

[0084] Figures 2 and 3 show the elution profiles for olaparib concentration and olaparib dose, respectively. Elution of olaparib was essentially complete within 5-6 hours. Pseudo sink, jar method (USP2 method): Olaparib-loaded microspheres (75–150 μM) were placed in 400 mL of PBS and magnetically stirred at 37 °C. After 1 h, 5 mL of the solution was replaced with fresh PBS, and the Olaparib concentration in the sample was measured by HPLC. The sample volume for each subsequent hour was 200 mL. The acquired data are shown in Figure 4.

[0085] Example 5: Suspension and catheter delivery One vial of olaparib-loaded microspheres obtained in Example 3 was reconstituted with 1 mL of water followed by 9 mL of Omnipaque® 350. The microspheres were delivered through a 24 G (1.7 Fr, 0.7 mm x 19 mm) microcatheter without any obstruction within the microcatheter.

[0086] Example 6: Preparation of PLGA / olaparib microspheres (60-150 μm) 0.4 g of PLGA (Evonik50 / 50 4A, Evonik Industries AG, Essen, Germany) and 40 mg of olaparib (MedChemExpress, Monmouth Junction, NJ, USA) were dissolved in 1.89 g of dichloromethane (DCM) in a glass vial. A 2% solids (w / w) solution of PVA (Aldrich, 146k-186kMW, Sigma-Aldrich, Saint Louis, MO, USA) in DI water in a 5 mL glass vial was stirred at 200 rpm using a magnetic stirrer. The DCM-dissolved PLGA-olaparib solution was added dropwise to the stirred PVA solution. The resulting microsphere dispersion was allowed to stir for 5 min, after which time it was transferred to a stirred solution of 150 mL of DI water. The microspheres were allowed to stir at 300 rpm (vigorously) for 4 h at room temperature. The resulting microsphere dispersion was then filtered through a 150 μm mesh filter, and the filter was rinsed three times with DI water. The microsphere dispersion was then poured through a 60 μm mesh filter. The microspheres collected on the filter were then dried overnight in a vacuum oven at room temperature.

[0087] Example 7: Determination of Olaparib content in encapsulated PGA microspheres One mg of microspheres was dissolved in 10 mL of acetonitrile (ACN) and the resulting solution was scanned using a UV-Vis spectrometer. The adsorption of olaparib was measured at a wavelength of 276 nm. The concentration of olaparib in the microspheres was determined by comparison with a series of olaparib standards. The content of olaparib in the PLGA microspheres was found to be 6.9% (w / w).

[0088] Example 8: Measurement of Olaparib release from PLGA microspheres 4 mg of microspheres were added to 10 mL of PBS / tween20 pH 7.4 (10 mM phosphate buffer, 140 mM NaCl, 2.7 mM KCl, 0.05% tween20, Calbiochem, San Diego, CA, USA) in a 15 mL centrifuge tube. The tube was placed horizontally in an incubator shaker set at 37°C and 120 rpm. The tube was removed at various time points and centrifuged (4000 rpm, 10 s). The PBS medium was removed from the tube and subjected to olaparib content analysis by UV-Vis spectroscopy at a wavelength of 276 nm. 10 mL of fresh PBS was added to the tube and the tube was placed back in the incubator until the next time point. As can be seen in Figure 5, olaparib was sustained released from the PLGA microspheres over a 14-day period.

Claims

1. A polymeric microsphere comprising a polymer and an inhibitor of the enzyme poly ADP ribose polymerase (PARP inhibitor), wherein the PARP inhibitor is retained within the polymeric microsphere and is elutable from the microsphere in an aqueous medium.

2. The polymer microsphere of claim 1, wherein at least a portion of the PARP inhibitor is retained within the microsphere by ionic interactions between the PARP inhibitor and the polymer and / or at least a portion of the PARP inhibitor is physically entrapped within the polymer microsphere.

3. 10. The polymeric microsphere of any of the preceding claims, wherein the PARP inhibitor is elutable from the polymeric microsphere in phosphate buffered saline (0.01 M phosphate buffered saline (0.138 M NaCl; 0.0027 M KCl), pH 7.4) at 37°C.

4. A polymer microsphere as described in any of the preceding claims, wherein the polymer has one or a combination of two or more of the following characteristics: (a) the polymer is anionically charged at pH 7.4; (b) the polymer is crosslinked; (c) the polymer is in the form of a hydrogel; and (d) the polymer is biodegradable or biodegradable.

5. The polymeric microsphere of any one of claims 1 to 4, wherein the polymer comprises a polyvinyl alcohol (PVA) homopolymer or a PVA copolymer.

6. The polymeric microsphere according to any one of claims 1 to 4, wherein the polymer is a polyester, a polysaccharide or a biodegradable PVA polymer.

7. The polymeric microsphere according to any one of claims 1 to 4, wherein said polymer consists of or comprises poly(lactic-co-glycolic acid) (PLGA) or is a biodegradable cross-linked PVA.

8. 2. The polymeric microsphere of any of the preceding claims, wherein the PARP inhibitor is selected from olaparib (AZD-2281), rucaparib (RF-01367338), niraparib (MK-4827), talazoparib (BMN-673), veliparib (ABT-888), CEP9722, E7016, BGB-290 and 3-aminobenzamide.

9. The polymer microsphere described in any one of claims 1 to 4, wherein the polymer microsphere is a hydrogel polymer microsphere comprising a cross-linked polyvinyl alcohol polymer or polyvinyl alcohol copolymer and the PARP inhibitor, and the cross-linked polyvinyl alcohol polymer is negatively charged at pH 7.

4.

10. 10. The polymeric microsphere of any preceding claim, further comprising a checkpoint inhibitor retained within the polymeric microsphere and elutable from the microsphere.

11. The polymer microsphere of claim 10, wherein the checkpoint inhibitor is selected from an inhibitor of PD-1 binding to PD-L1, an inhibitor of CTLA-4 binding to CD80 and / or CD86, an inhibitor of TIGIT binding to CD-112, and an inhibitor of LAG-3 binding to MHC class II.

12. The polymer microsphere of claim 10, wherein the checkpoint inhibitor is selected from an antibody or an antigen-binding fragment thereof that binds to PD-1, PD-L1, LAG-3, TIM-3, TIGIT, or CTLA-4.

13. 11. The polymeric microsphere of claim 10, wherein the checkpoint inhibitor is selected from pembrolizumab, nivolumab, ipilimumab, atezolizumab, avelumab, tremelimumab, leratolimab, durvalumab, etigilimab, dombanalimab, tiragolumab, vibostolimab, LY3321367, MBG453, and TSR-022.

14. A PARP inhibitor for use in the treatment of solid tumors, wherein the PARP inhibitor is provided within a plurality of polymer microspheres comprising the PARP inhibitor and a polymer, the PARP inhibitor being retained within the polymer microspheres and being elutable from the microspheres in an aqueous medium.

15. Use of a PARP inhibitor in the manufacture of a therapeutic agent for the treatment of solid tumors, wherein the PARP inhibitor is provided within a plurality of polymer microspheres comprising the PARP inhibitor and a polymer, the PARP inhibitor being retained within the polymer microspheres and being elutable from the microspheres in an aqueous medium.

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