Microsphere-based drug delivery platform for delivery of immunotherapeutic agents

Abstract

The present disclosure relates to biodegradable polymeric microspheres comprising a biodegradable polymer and an immunotherapeutic agent selected from the group consisting of a poly ADP ribose polymerase inhibitor (PARP inhibitor) and / or a Toll-like receptor (TLR) agonist, wherein (a) 50% of the total amount of the immunotherapeutic agent in the biodegradable polymer microspheres is released from the biodegradable polymer microspheres to a PBS solution containing 0.05% of Tween 20 at 37 DEG C at a certain time point between 3 days and 14 days; (b) releasing the immunotherapeutic agent with the dry weight of 1 mg / g to 100 mg / g from the biodegradable polymer microspheres to a PBS solution containing 0.05% of Tween 20 at 37 DEG C at a certain time point between 3 days and 14 days; or (c) satisfies both (a) and (b). Other aspects of the present disclosure relate to methods of using such microparticles and kits comprising such microparticles.

Description

Cross Reference to Related Applications

[0001] This application claims priority to U.S. Provisional Patent Application No. 63 / 492,063, filed March 24, 2023, the disclosure of which is incorporated herein by reference. BACKGROUND

[0002] In many cancer indications, immunotherapy has rapidly become the standard of care. However, only a small fraction of patients respond to this therapy. Recently, the focus of research has shifted to developing more effective combination therapies and immunomodulators. It is known that many of these new generation immunotherapies are capable of inducing potent anti-tumor immune responses. However, the systemic delivery of these immunotherapeutic agents is hindered by strong off-target toxicities. Therefore, there is a need for a drug delivery system that can deliver immunotherapeutic agents to the target tumor in a targeted and controllable manner, thereby increasing the efficacy while reducing or eliminating off-target toxicities. SUMMARY

[0003] In some aspects, the present disclosure relates to microspheres comprising a biodegradable polymer and an immunotherapeutic agent selected from a poly ADP ribose polymerase inhibitor (PARP inhibitor) and / or a Toll-like receptor (TLR) agonist, wherein 50% of the total amount of the immunotherapeutic agent in the biodegradable polymer microspheres is released from the biodegradable polymer microspheres into a PBS solution containing 0.05% Tween 20 at 37°C at a time point between 3 days and 14 days.

[0004] In some aspects, which can be used in combination with the above aspects, the present disclosure relates to microspheres comprising a biodegradable polymer and an immunotherapeutic agent selected from a poly ADP ribose polymerase inhibitor (PARP inhibitor) and / or a Toll-like receptor (TLR) agonist, wherein 1 mg / g of microspheres dry weight to 100 mg / g of microspheres dry weight of the immunotherapeutic agent is released from the biodegradable polymer microspheres into a PBS solution containing 0.05% Tween 20 at 37°C at a time point between 3 days and 14 days.

[0005] In some embodiments, which can be used in combination with the above aspects and embodiments, the immunotherapeutic agent is dispersed throughout the particle in the form of nanoparticles having a size of 100 nm to 2000 nm.

[0006] In some embodiments, which can be used in combination with the above aspects and embodiments, the biodegradable polymer microspheres contain 3% to 10% by weight of the immunotherapeutic agent, based on the dry weight of the biodegradable polymer microspheres.

[0007] In some embodiments, which can be used in combination with the above aspects and embodiments, the biodegradable polymer microspheres have a diameter of 30 microns to 200 microns.

[0008] In some embodiments, which can be used in combination with the above aspects and embodiments, the immunotherapeutic agent is released by bulk erosion and hydrolysis.

[0009] In some embodiments, which can be used in combination with the above aspects and embodiments, the biodegradable polymer is a biodegradable polyester.

[0010] In some embodiments, which can be used in combination with the above aspects and embodiments, the biodegradable polymer consists of or comprises poly(lactide-co-glycolide) (PLGA). In some of these embodiments, the ratio of lactide units to glycolide units in the PLGA is 60:40 to 40:60, typically 50:50. In some of these embodiments, the PLGA comprises carboxy-terminated PLGA, or the PLGA comprises a mixture of carboxy-terminated PLGA and ester-terminated PLGA.

[0011] In some embodiments, which can be used in combination with the above aspects and embodiments, the biodegradable polymer microspheres further comprise a pharmaceutical excipient selected from the group consisting of a preservative, an isotonicity modifier, a viscosity modifier, a pH modifier, a contrast agent, a detergent, and / or a sugar or sugar alcohol.

[0012] In some embodiments, which can be used in combination with the above aspects and embodiments, the biodegradable polymer microspheres are provided in dry form.

[0013] In some embodiments, which can be used in combination with the above aspects and embodiments, the biodegradable polymer microspheres are provided in an aqueous liquid.

[0014] In some embodiments, which can be used in combination with the above aspects and embodiments, the biodegradable polymer microspheres are provided in a vial or a syringe.

[0015] In some aspects, the present disclosure relates to a kit comprising: (a) biodegradable polymer microspheres according to the above aspects and embodiments; and (b) any one, any two, any three, any four, any five, or all six of: a syringe barrel, a vial, a needle, a catheter, a guidewire, or an injectable liquid.

[0016] In some aspects, the present disclosure relates to a method of treating a patient having a solid tumor, the method comprising delivering to the solid tumor biodegradable polymer microspheres according to the above aspects and embodiments.

[0017] In some implementations, biodegradable polymer microspheres are delivered by direct injection into the tumor.

[0018] In some embodiments, biodegradable polymer microspheres are delivered to one or more blood vessels supplying at least a portion of the tumor, and at least a portion of the biodegradable polymer microspheres remain in the blood vessel to form an embolus.

[0019] In some embodiments that can be used in conjunction with the above aspects and implementation methods, the method further includes treating the solid tumor with radiotherapy.

[0020] These and other aspects, embodiments, and advantages of this disclosure will become apparent to those skilled in the art upon reading the following detailed description and claims. BRIEF DESCRIPTION OF DRAWINGS

[0021] FIG. 1 This is a photomicrograph of biodegradable polymer microspheres prepared according to the embodiments of this disclosure.

[0022] FIG. 2 The diagram shows the drug release kinetics of imiquimod-containing biodegradable polymer microspheres and olaparib-containing biodegradable polymer microspheres in PBS Tween solution at 37°C, according to embodiments of the present disclosure. Detailed Implementation

[0023] In various respects, this disclosure relates to biodegradable polymer microspheres loaded with immunotherapeutic agents of interest. These biodegradable polymer microspheres can be used to deliver immunotherapeutic agents to solid tumors, for example, by direct injection or as an embolic agent via one or more blood vessels supplying the tumor. This approach enables targeted and controlled delivery of potent immunotherapeutic agents, thereby improving efficacy at the target site while reducing off-target toxicity.

[0024] In some embodiments, this disclosure relates to biodegradable polymer microspheres comprising a biodegradable polymer and an immunotherapeutic agent, wherein at 37°C, 50% of the total immunotherapeutic agent in the biodegradable polymer microspheres is released from the biodegradable polymer microspheres into a PBS solution containing 0.05% Tween 20 at some time point between 3 and 14 days. In some embodiments, the immunotherapeutic agent released at 3 days is less than 50%, less than 40%, less than 30%, or less than 25%, and / or at 14 days is greater than 50%, greater than 60%, greater than 70%, or greater than 80%.

[0025] In some embodiments, the present disclosure relates to biodegradable polymer microspheres comprising a biodegradable polymer and an immunotherapeutic agent, wherein between 1 mg and 100 mg of the immunotherapeutic agent per 1 gram of microspheres dry weight (e.g., between 1 mg, 2 mg, 5 mg, 10 mg, 25 mg, 50 mg, 100 mg per 1 gram of microspheres dry weight) is released from the biodegradable polymer microspheres into a PBS solution containing 0.05% Tween 20 at some point between 3 days and 14 days.

[0026] In some embodiments, the immunotherapeutic agents for use in the present disclosure include poly ADP ribose polymerase (PARP) inhibitors and / or Toll-like receptor (TLR) agonists.

[0027] Examples of PARP inhibitors include olaparib (AZD-2281), rucaparib (PF-01367338), niraparib (MK-4827), talazoparib (BMN-673), veliparib (ABT-888), CEP 9722, E7016, BGB-290, and 3-aminobenzamide, among others.

[0028] Examples of TLR agonists include TLR3, TLR4, TLR7, TLR8, and TLR9 agonists. More specific TLR agonists include TLR7 / 8 agonists selected from imidazoquinoline derivatives (IMDs) (e.g., imiquimod, resiquimod (R848), gardiquimod, 852-A (PF-4878691), MEDI9197, and the like), cinnolone derivatives (e.g., visatolimod (GS-9620)), 8-oxo-adenine derivatives (e.g., AZD-8848 and the like), TMX-202, benzazol analogues (e.g., motolimod (VTX-2337) and the like), and pyrimidine analogues (e.g., selgantolimod (GS-9688) and the like), among others. More specific TLR9 agonists include CpG oligodeoxynucleotides (e.g., atotolimod and the like), lefitolimod (MGN1703), and tilsotolimod, among others.

[0029] In some embodiments, the immunotherapeutic agents for use in the present disclosure include small molecule (i.e., molecular weight less than 3000 daltons) PARP inhibitors and / or TLR agonists.

[0030] In some embodiments, the immunotherapeutic agent is dispersed throughout the biodegradable polymer microspheres in the form of particles. For example, the immunotherapeutic agent can be in the form of nanoparticles having a size of 100 nanometers to 2000 nanometers, more typically 250 nanometers to 1000 nanometers, or other sizes. Such particle sizes can be obtained, for example, by grinding the immunotherapeutic agent to the desired size.

[0031] Biodegradable polymer microspheres can be prepared by a variety of known techniques by those skilled in the art, such as single and double emulsion techniques, solvent evaporation techniques, suspension polymerization techniques, solvent extraction techniques, and combinations thereof. In particular embodiments, including the embodiments described herein, emulsion-solvent evaporation techniques are employed to prepare the biodegradable polymer microspheres. The biodegradable polymer microspheres of the present disclosure are particularly suitable for embolization because the size of the microspheres can be controlled by sieving or other fractionation techniques. Furthermore, because the biodegradable polymer microspheres are spherical in shape, unwanted aggregation can be avoided.

[0032] Biodegradable polymer microspheres can have a wide range of drug loading. In some embodiments, the biodegradable polymer microspheres contain 1% to 20% by weight of the immunotherapeutic agent, more typically 3% to 10% by weight of the immunotherapeutic agent, based on dry weight.

[0033] Biodegradable polymer microspheres can have a wide range of particle sizes. For example, the biodegradable polymer microspheres can have a diameter of 10 micrometers to 500 micrometers, typically 30 micrometers to 200 micrometers, more typically 60 micrometers to 150 micrometers.

[0034] Biodegradable polymer microspheres can undergo biodegradation in vivo by a variety of processes, including bulk erosion and surface erosion.

[0035] Biodegradable polymer microspheres comprise one or more biodegradable polymers. In some embodiments, the biodegradable polymer undergoes degradation by hydrolysis. In some embodiments, the biodegradable polymer is a biodegradable polyester.

[0036] Examples of biodegradable polyesters include polylactides (such as poly(lactide) (PLA)), polyglycolides (such as poly(glycolide) (PLG)), polyhydroxyalkanoates (such as poly(hydroxybutyrate) or poly(hydroxyvalerate)), polylactones (such as poly-γ-butyrolactone, poly-δ-valerolactone, or poly-ε-caprolactone), poly(alkylene dicarboxylates) (such as poly(butylene succinate) or poly(butylene adipate)), poly(p-dioxanone), poly(trimethylenecarbonate), and copolymers comprising two, three, or a single combination of any of the foregoing polymers, including poly(lactide-co-glycolide) (PLGA), poly(3-hydroxybutyrate-co-3-hydroxyvalerate), and poly(butylene succinate-co-adipate), among others.

[0037] In some embodiments, the biodegradable polymer microspheres comprise one or more biodegradable polyesters in an amount of 80-99% by weight (dry weight), and more typically 90-97% by weight (dry weight).

[0038] The biodegradable polyesters can have a variety of molecular weights, such as a number average molecular weight of 500 to 250,000 Daltons, and in some embodiments, 1000 to 20,000 Daltons.

[0039] The biodegradable polyesters can have a variety of end group functionalities, including polyesters containing one or more carboxyl end groups (e.g., carboxyl-terminated PLGA, which contains carboxyl end groups), polyesters containing one or more ester end groups (e.g., ester-terminated PLGA, including methyl-ester terminated PLGA, ethyl-ester terminated PLGA, propyl-ester terminated PLGA, and the like), or polyesters containing one or more hydroxyl groups.

[0040] The biodegradable copolyesters can have a variety of monomer ratios. For example, a biodegradable copolyester containing two monomers can have a monomer ratio of 1 :99, 10:90, 25:75, 35:65, 50:50, 65:35, 75:25, 90:10, or 99:1 (i.e., a range between any of the two ratios described above).

[0041] In certain advantageous embodiments, the biodegradable polymer microspheres comprise two or more biodegradable polyesters. Examples include: (a) a combination of biodegradable polyesters formed from different monomers (e.g., a combination of PLA and PLGA, and the like); (b) a combination of biodegradable polyesters formed from the same monomers but having different molecular weights; (c) a combination of biodegradable polyesters formed from the same monomers but having different end groups (e.g., a combination of carboxyl-terminated PLGA and ester-terminated PLGA, and the like); (d) a combination of biodegradable copolyesters formed from the same monomers but having different monomer ratios (e.g., a combination of 50:50 PLGA and 75:25 PLGA, and the like); (e) a combination of any two or all three of (b), (c), and (d) above.

[0042] The biodegradable polymer microspheres of the present disclosure can be stored and transported as a sterile dry composition. The dry composition can be, for example, shipped in a syringe, vial, ampoule, catheter, or other container (e.g., any container that can be used in conjunction with a needle or delivery catheter). Prior to administration, the dry composition can be mixed with a suitable liquid carrier (e.g., sterile water for injection, normal saline, phosphate buffered saline, a solution containing an imaging contrast agent, and the like). In this manner, the concentration of biodegradable polymer microspheres in the composition to be injected can be adjusted at the discretion of the medical practitioner responsible for the procedure, depending on the particular application. One or more containers containing the liquid carrier can also be provided and shipped with the dry particles in a kit.

[0043] The biodegradable polymer microspheres can be stored in a sterile liquid suspension containing the biodegradable polymer microspheres and an aqueous or non-aqueous liquid, so long as unacceptable degradation does not occur (which is related to the polymer properties, solution properties, shelf life requirements, etc.). As with the dry compositions, the liquid suspensions can be stored, for example, in syringes, vials, ampoules, catheters, or other containers. The liquid suspensions can also be mixed with a suitable liquid carrier (e.g., sterile water for injection, normal saline, phosphate buffered saline, solutions containing contrast media, etc.) prior to administration, and the concentration of biodegradable polymer microspheres in the suspension to be injected can be reduced prior to injection, if desired by the medical personnel in charge. One or more containers of liquid carrier can also be provided in a kit.

[0044] The dry composition or liquid suspension containing the biodegradable polymer microspheres can also optionally contain other agents, such as agents selected from the group consisting of imaging agents, isotonicity adjusting agents, suspending agents, wetting agents, pH adjusting agents, and coloring agents. Examples of imaging agents include: (a) fluorescent dyes, such as fluorescein, indocyanine green, or fluorescent proteins (e.g., green, blue, cyan fluorescent proteins); (b) contrast agents for magnetic resonance imaging (MRI), including contrast agents containing elements that form paramagnetic ions, such as gadolinium (III), manganese (II), iron (III), and compounds containing these ions, including chelates, such as gadolinium ions chelated with diethylenetriaminepentaacetic acid; (c) contrast agents for ultrasound imaging, including organic and inorganic echogenic particles (i.e., particles that increase reflected ultrasound energy) or organic and inorganic anechogenic particles (i.e., particles that decrease reflected ultrasound energy); (d) contrast agents for near-infrared (NIR) imaging, which can be selected to impart near-infrared fluorescence properties to the hydrogels of the present disclosure, thereby enabling deep tissue imaging and device labeling, such as near-infrared sensitive nanoparticles, such as gold nanoshells, carbon nanotubes (e.g., nanotubes with hydroxyl or carboxyl groups, such as partially oxidized carbon nanotubes), dye-containing nanoparticles (such as dye-doped nanofibers and dye-encapsulated nanoparticles), and semiconductor quantum dots, among others, and near-infrared sensitive dyes, such as cyanine dyes, squarine dyes, phthalocyanines, porphyrin derivatives, and boron-dipyrromethene (BODIPY) analogs, among others; (e) imageable radioisotopes, including 99mTc, 201Th, 51Cr, 67Ga, 68Ga, 111In, 64Cu, 89Zr, 59Fe, 42K, 82Rb, 24Na, 45Ti, 44Sc, 51Cr, and 177Lu, among others; (f) radiographic contrast agents, such as metallic particles (e.g., tantalum, tungsten, rhenium, niobium, molybdenum particles and alloys thereof, which can be spherical or non-spherical), non-ionic radiographic contrast agents (such as iohexol, iodixanol, ioversol, iopamidol, ioversol, or iopromide), ionic radiographic contrast agents (such as diatrizoic acid, iodized poppycarmine, metrizoic acid, or ioxaglate), and iodinated oils (including ethyl iodophylate, trade name ).

[0045] Examples of other agents also include isotonicity adjusting agents, such as sugars (e.g., dextrose, lactose, etc.), polyols (e.g., glycerol, propylene glycol, mannitol, sorbitol, etc.), and inorganic salts (e.g., potassium chloride, sodium chloride, etc.), among others; suspending agents, including various surfactants, wetting agents, and polymers (e.g., albumin, polyethylene oxide (PEO), polyvinyl alcohol, block copolymers, etc.), among others; and pH adjusting agents, including various buffer solutes. Examples of coloring agents include Brilliant Blue (e.g., Food, Drug, and Cosmetic Brilliant Blue, also known as FD&C Blue No. 1), Indigo Carmine (also known as FD&C Blue No. 2), Indigo Carmine Lake, FD&C Blue No. 1 Lake, and methylene blue (also known as methylene blue chloride), among others.

[0046] In various embodiments, the present disclosure provides kits comprising one or more delivery devices for delivering the biodegradable polymer microspheres of the present disclosure to a subject. Such kits can comprise one or more of the following: a syringe barrel (which can or can not be filled with the biodegradable polymer microspheres described herein); a vial (which can or can not be filled with the biodegradable polymer microspheres described herein); a needle; a flexible tube (e.g., a catheter); a guidewire; and an injectable liquid (such as water for injection, normal saline, phosphate buffered saline, a solution containing an imaging contrast agent, etc.). Where a catheter is provided, the catheter can be used to inject the biodegradable polymer microspheres into a blood vessel of a patient, and a guidewire can be used to position the catheter within the blood vessel. Whether the biodegradable polymer microspheres are contained in a syringe, vial, or other reservoir, they can be provided in the form of a dry composition or a liquid suspension as described above.

[0047] In various embodiments, the compositions comprising the biodegradable polymer microspheres of the present disclosure are sterile. The compositions can be sterilized by any method known in the art, for example, by sterilization via radiation (such as gamma, beta, or X-ray radiation). In certain embodiments, the biodegradable polymer microspheres are aseptically prepared using aseptic techniques.

[0048] In other aspects, the present disclosure provides methods of treating a patient having a solid tumor, the method comprising delivering to the solid tumor a composition comprising the biodegradable polymer microspheres of the present disclosure (e.g., a liquid suspension of the biodegradable polymer microspheres). Examples of solid tumors include liver tumors, pancreatic tumors, uterine tumors, brain tumors, kidney tumors, bone tumors, breast tumors, bladder tumors, prostate tumors, colon tumors, lung tumors, oral and / or neck tumors, esophageal tumors, endometrial tumors, ovarian tumors, stomach tumors, and the like. The amount of immunotherapeutic agent delivered to a solid tumor will vary, for example, depending on the particular immunotherapeutic agent being administered, the type of tumor, the size of the tumor, the patient’s condition, and the like. In some embodiments, the solid tumor can also be treated with radiation therapy.

[0049] Methods of administration of the biodegradable polymer microspheres include transdermal techniques as well as other effective routes of administration.

[0050] For example, in some embodiments, a composition comprising the biodegradable polymer microspheres of the present disclosure can be delivered by direct injection into a tumor. For example, the biodegradable polymer microspheres can be delivered through a 24 gauge or finer needle.

[0051] In some embodiments, the composition comprising biodegradable polymer microspheres of the present disclosure is delivered to one or more blood vessels (e.g., a blood supplying artery) that supply at least a portion of the tumor with blood, wherein at least a portion of the biodegradable polymer microspheres lodge in the blood vessel to form an embolus. For example, the biodegradable polymer microspheres can be delivered through a catheter sized 1.2 French and above.

[0052] Once delivered to the tumor, the immunotherapeutic agent is released locally by hydrolysis-based biodegradation of the biodegradable polymer microspheres. Subsequently, the immunotherapeutic agent is delivered in a local, controlled manner over a period of days to weeks. This enables the local immunotherapeutic agent dose to be maintained within the immunotherapeutic window while minimizing systemic distribution. Examples

[0053] The examples used the following PLGA products, which were purchased from Evonik Industries AG, Essen, Germany: RG 501H, a carboxyl-terminated poly(D,L-lactide-co-glycolide) with a molar ratio of lactide to glycolide of 50:50 and an intrinsic viscosity of 0.8-0.16 deciliters / gram; RG 502, an ester-terminated poly(D,L-lactide-co-glycolide) with a molar ratio of lactide to glycolide of 50:50, a weight average molecular weight (Mw) of 7000-17000, and an intrinsic viscosity of 0.16-0.24 deciliters / gram; RG 502H, a carboxyl-terminated poly(D,L-lactide-co-glycolide) with a molar ratio of lactide to glycolide of 50:50, a weight average molecular weight (Mw) of 7000-17000, and an intrinsic viscosity of 0.16-0.24 deciliters / gram; and RG 503H, a carboxyl-terminated poly(D,L-lactide-co-glycolide) with a molar ratio of lactide to glycolide of 50:50 and an intrinsic viscosity of 0.16-0.24 deciliters / gram.

[0054] The PLGA (weight ratio of RG 501H to RG 502 was 50:50 when preparing the imiquimod microspheres; weight ratio of RG 501H to RG 502H was 50:50 for 2A samples or weight ratio of RG 501H to RG 503H was 50:50 for 4A samples when preparing the olaparib microspheres) was dissolved in dichloromethane (DCM) to form a 2-milliliter PLGA solution with a concentration of <25% weight / volume of PLGA in the solution. The PLGA was allowed to dissolve under ambient temperature with stirring for 30 minutes.

[0055] The immunotherapeutic agent (Imiquimod or Olaparib) was ground in dichloromethane (DCM) to a size of 500-1000 nanometers and then added to the PLGA solution in different amounts, up to 12% of the weight of PLGA in the solution, forming a PLGA / immunotherapeutic agent organic solution.

[0056] The surfactant / stabilizer (e.g., polyvinyl alcohol (PVA)) was dissolved in water (e.g., sterile water or deionized water) to form a 5 milliliter PVA solution with a concentration of 2% weight / volume. The PVA was dissolved by stirring vigorously at a temperature up to 80 °C for 1 hour or until complete dissolution, forming a PVA aqueous solution.

[0057] The PLGA / immunotherapeutic agent organic solution was added to the PVA aqueous solution by dropwise addition or through a graduated needle at ambient temperature while stirring at 300 revolutions per minute. The resulting mixture was then homogenized for 5 minutes, forming an oil-in-water emulsion. The emulsion was diluted with sterile water by a factor of about 2 and incubated overnight at ambient temperature (25 °C) with stirring at 150 revolutions per minute.

[0058] The resulting microsphere mixture was then added to 250 milliliters of a 1% PVA solution and incubated at 31 °C with stirring at 80 revolutions per minute for 48 hours. The liquid phase was decanted and the biodegradable polymer microspheres were washed with 100 milliliters of sterile water. This washing step was repeated 3 times. The resulting microspheres were then filtered through a 150 micron screen and then through an 80 micron or 100 micron woven nylon mesh, resulting in particles with a size of 80-150 microns or 100-150 microns. The fractionated particles were vacuum dried at ambient temperature for >12 hours. FIG. 1

[0059] The resulting microsphere mixture was then added to 250 milliliters of a 1% PVA solution and incubated at 31 °C with stirring at 80 revolutions per minute for 48 hours. The liquid phase was decanted and the biodegradable polymer microspheres were washed with 100 milliliters of sterile water. This washing step was repeated 3 times. The resulting microspheres were then filtered through a 150 micron screen and then through an 80 micron or 100 micron woven nylon mesh, resulting in particles with a size of 80-150 microns or 100-150 microns. The fractionated particles were vacuum dried at ambient temperature for >12 hours.

[0060] Preparation of acetate buffer (pH ~ 4): 0.93 grams of sodium acetate and 2.321 milliliters of glacial acetic acid were dissolved in 500 milliliters of water.

[0061] Determination of the content of the immunotherapeutic agent in the biodegradable polymer microspheres: About 1 milligram of biodegradable polymer microspheres was weighed in a vial, 10 milliliters of 1:1 acetonitrile (ACN): acetate buffer was added, the biodegradable polymer microspheres were dissolved, and a UV-visible spectrum was taken (for Imiquimod, detection wavelengths = 241 nanometers or 319 nanometers; for Olaparib, detection wavelength = 253 nanometers), and the concentration of the immunotherapeutic agent (micrograms / milliliter solution) was calculated using the slope of the previously determined immunotherapeutic agent standard. The weight percent of the immunotherapeutic agent in the biodegradable polymer microspheres was calculated from this concentration. The results of the determination showed that the content of Imiquimod in the biodegradable polymer microspheres was about 7% weight / volume and the content of Olaparib was about 5% weight / volume.​

[0062] Determination of drug release kinetics from biodegradable polymer microspheres: About 1 mg of biodegradable polymer microspheres was weighed in a centrifuge tube, 10 mL of PBS Tween solution was added, and incubated at 37 °C at 120 rpm on a shaker. For each target time point (e.g., 3 days, 7 days, 10 days, 14 days, 21 days), the biodegradable polymer microspheres were centrifuged, and the medium was aspirated. Subsequently, 5 mL of 1 : 1 acetonitrile (ACN): acetate buffer (pH 4) was added directly to the biodegradable polymer microspheres, and UV-Vis spectroscopy was performed. The weight percent of the remaining immunotherapeutic agent in the biodegradable polymer microspheres was calculated using the measured immunotherapeutic agent concentration. Drug release kinetics results are shown in FIG. 2 Cross Reference to Related Applications BRIEF DESCRIPTION OF DRAWINGS FIG. 1 FIG Figure 6.

Claims

1. Biodegradable polymer microspheres comprising a biodegradable polymer and an immunotherapeutic agent, said immunotherapeutic agent being selected from poly-ADP-ribose polymerase inhibitors (PARP inhibitors) and / or Toll-like receptor (TLR) agonists, wherein: (a) 50% of the total amount of immunotherapy agent in the biodegradable polymer microspheres is released from the biodegradable polymer microspheres into a PBS solution containing 0.05% Tween 20 at 37°C at some time point between 3 and 14 days; (b) 1 mg / g dry weight to 100 mg / g dry weight of immunotherapy agent is released from the biodegradable polymer microspheres into a PBS solution containing 0.05% Tween 20 at 37°C at some time point between 3 and 14 days. Or (c) both (a) and (b) are satisfied.

2. The biodegradable polymer microspheres according to claim 1, wherein the immunotherapeutic agent is dispersed throughout the particles in the form of nanoparticles, the nanoparticles having a size of 100 nanometers to 2000 nanometers.

3. The biodegradable polymer microspheres according to claim 1 or claim 2, wherein the biodegradable polymer microspheres contain 3% to 10% by weight of an immunotherapeutic agent based on the dry weight of the biodegradable polymer microspheres.

4. The biodegradable polymer microspheres according to any one of claims 1-3, wherein the diameter of the biodegradable polymer microspheres is from 30 micrometers to 200 micrometers.

5. The biodegradable polymer microspheres according to any one of claims 1-4, wherein the immunotherapeutic agent is released through bulk erosion and hydrolysis.

6. The biodegradable polymer microspheres according to any one of claims 1-5, wherein the biodegradable polymer is a biodegradable polyester.

7. The biodegradable polymer microspheres according to any one of claims 1-6, wherein the biodegradable polymer is composed of or contains poly(lactide-co-glycolic acid) (PLGA).

8. The biodegradable polymer microspheres according to claim 7, wherein the ratio of lactide units to glycolide units in the PLGA is 60:40 to 40:

60.

9. The biodegradable polymer microspheres according to claim 7, wherein the ratio of lactide units to glycolide units in the PLGA is 50:

50.

10. The biodegradable polymer microspheres according to any one of claims 7-9, wherein the PLGA comprises terminal carboxyl PLGA.

11. The biodegradable polymer microspheres according to any one of claims 7-9, wherein the PLGA comprises a mixture of terminal carboxyl PLGA and terminal ester PLGA.

12. The biodegradable polymer microspheres according to any one of claims 1-11, further comprising a pharmaceutical excipient selected from: preservatives, isotonic modifiers, viscosity modifiers, pH modifiers, contrast agents, detergents, or sugars or sugar alcohols.

13. The biodegradable polymer microspheres according to any one of claims 1-12, wherein the biodegradable polymer microspheres are provided in a dry form.

14. The biodegradable polymer microspheres according to any one of claims 1-12, wherein the biodegradable polymer microspheres are provided in an aqueous liquid.

15. The biodegradable polymer microspheres according to any one of claims 1-14, wherein the biodegradable polymer microspheres are provided in a vial or syringe.

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