Solid compositions for production of micelles for drug delivery

Abstract

The present technology relates to compositions comprising a crystalline PEG copolymer, a hydrophobic drug, and optionally a PEG homopolymer, wherein the composition is solid; the crystalline PEG copolymer has at least one crystalline PEG block and at least one polymer block other than PEG; the PEG homopolymer has a molecular weight from about 200 Da to about 800 Da; and the hydrophobic drug has a water solubility of <10 mg / mL at 25 °C. Also provided are methods of making such compositions and for making drug-delivery micelles from such compositions.

Description

SOLID COMPOSITIONS FOR PRODUCTION OF MICELLESFOR DRUG DELIVERYCROSS-REFERENCE TO RELATED PATENT APPLICATIONS

[0001] This application claims the benefit of and priority of U.S. Provisional Patent Application 63 / 535,515, filed August 30, 2023, the entire contents of which is incorporated herein by reference in its entirety.STATEMENT OF GOVERNMENT SUPPORT

[0002] This invention was made with government support under CA257837 awarded by the National Institutes of Health. The government has certain rights in the invention.FIELD

[0003] The present disclosure relates generally to solid compositions for the production of micelles for drug delivery and methods of making and using such compositions. The solid compositions include a crystalline PEG copolymer, a hydrophobic drug and optionally, a PEG homopolymer.BACKGROUND

[0004] Despite the potential advantages, a relatively small number of nanomedicine formulations have been approved for clinical use to date. The complex nature of nanomedicines compared with standard pharmaceuticals poses numerous challenges and obstacles in different stages of development. A reproducible scale-up and manufacturing process to obtain a consistent product with desired physicochemical and biological characteristics is important for any formulation, especially in the later stages of development. Polymeric micelles, formed by the self-assembly of diblock or multiblock copolymers, constitute an important subset of nanocarriers for drug delivery. Among their diverse applications, the solubilization of water-insoluble or poorly soluble drugs stands out as a key advantage. These micelles eliminate the necessity to solubilize drugs using toxic solubilizers such as ethanol or low molecular weight surfactants such as the paclitaxel delivery vehicle Cremophore EL - a derivative of castor oil. Therefore, polymeric micelles enhance the safety profile of drug formulations. Additionally, polymeric micelles offer the potential to bedesigned for controlled release of the payload and targeted drug delivery for various diseases, including cancer treatment.

[0005] Diblock copolymers self-assemble into polymeric micelles in a selective environment for one of the blocks. For instance, the formation of PEG-b-PLA micelles in water is due to the preferential interaction of the PEG block with water. When the copolymer is water-insoluble, drug-loaded polymeric micelles are fabricated by dissolving both the copolymer and drug in a non-selective organic solvent, followed by replacement of the organic solvent with water as the selective solvent for the shell forming block.

[0006] For long-term storage, the aqueous suspension of drug-loaded polymeric micelles needs to be transformed into a dehydrated solid form typically achieved by lyophilization. Nanoparticles suspended in an aqueous medium are physically unstable due to particle aggregation and fusion. They are susceptible to drug leakage due to the hydrolytic action of water on the biodegradable polymer matrix, and the formation of undesirable degradation products Water also facilitates the growth of microorganisms which renders the formulation unacceptable for administration. Therefore, the current approach for formulating most drug- loaded polymeric micelles is a two-step procedure that involves (i) the production of an aqueous suspension of drug-loaded micelles and (ii) transforming it to a dehydrated solid form through lyophilization. The drug-loaded polymeric micelles can be reconstituted through hydration before use. Only in a few cases, where the copolymer is water-soluble, a one-step freeze-drying method, which involves the use of a mixture of tert-butanol / water can be employed successfully to obtain a dehydrated solid form that produces micelles upon hydration.SUMMARY

[0007] In one aspect, the present technology provides a solid composition that can be dissolved in water to provide polymeric micelles loaded with a therapeutic and suitable for delivering the therapeutic to a subject. The compositions include a crystalline PEG copolymer, a hydrophobic drug, and optionally a PEG homopolymer, wherein the composition is solid; the crystalline PEG copolymer has at least one crystalline PEG block and at least one polymer block other than PEG; the PEG homopolymer has a molecular weight from about 200 Da to about 800 Da; and the hydrophobic drug has a water solubilityof <10 mg / mL at 25 °C. The solid compositions are produced without using lyophilization, allowing for manufacture of the solid compositions in a cost-efficient and scalable manner.

[0008] In any embodiments, the PEG copolymer may be a di-block or tri -block copolymer. In any embodiments, it may be that the at least one polymer block other than PEG is crystalline. In any embodiments, it may be that the at least one polymer block other than PEG is non-crystalline.

[0009] In any embodiments, it may be that the at least one polymer block other than PEG is poly(D,L-lactic acid) (PLA), poly(s-caprolactam) (PCL), poly(lactic-co-glycolic acid), polypropylene oxide (PPO), poly(methyl methacrylate) (PMMA), poly(N- isopropyl acrylamide) (PNIPAM), polystyrene, poly(L-lactic acid), poly(D-lactic acid).

[0010] In any embodiments, the molecular weight of the crystalline PEG copolymer may be about 1.5 kDa to about 50 kDa. In any embodiments, the molecular weight of the crystalline PEG copolymer may be about 3 kDa to about 10 kDa.

[0011] In any embodiments, the ratio of the molecular weight of the crystalline PEG bloc(s) to the molecular weight of the non-crystalline bloc(s) may be from 15: 1 to 1 : 15. In any embodiments, the ratio of the molecular weight of the crystalline PEG bloc(s) to the molecular weight of the non-crystalline bloc(s) may be from 4: 1 to 1 :4. In any embodiments, the ratio of the molecular weight of the crystalline PEG bloc(s) to the molecular weight of the non-crystalline bloc(s) may be from 5 :2 to 1 : 1.

[0012] In any embodiments, the PEG copolymer may be PEG-b-PLA.

[0013] In any embodiments, the PEG block may have a molecular weight of about 1.5 kDa to about 35 kDa and the PLA block may have a molecular weight of about 1 to about 35 kDa. In any embodiments, the PEG block may have a molecular weight of about 1.5 to about 10 kDa and the PLA block may have a molecular weight of about 1.5 to about 16 kDa. In any embodiments, the PEG block may have a molecular weight of about 4 kDa and the PLA block may have a molecular weight of about 2.2 kDa. In any embodiments, the PEG homopolymer may have a molecular weight of about 200 to about 600 Da.

[0014] In any embodiments, the composition may include about 1 wt% to about 50 wt% hydrophobic drug by total weight of the solid composition. In any embodiments, thecomposition may include about 2 wt% to about 15 wt% hydrophobic drug by total weight of the solid composition.

[0015] In any embodiments, the drug may be selected from the group consisting of paclitaxel, docetaxel, rapamycin, everolimus, selumetinib, binimetinib, gefitinib-based PROTAC 3, GDC-0623, ARRY-300, cabazitaxel, rapamycin, ICU 189150, doxorubicin, etoposide, 17-AAG, bicalutamide, embelin, suberoylanilide hydroxamic acid, P-lapachone, pifithrin-p, sagopilone, thiocoraline, ABT-263, podophyllotoxin, simvastatin, efavirenz, a platin prodrug, VE-822, AZD5363, teniposide, AZD8055, rutin, derivatives and / or conjugates of any of the foregoing, and combinations of two or more thereof. In any embodiments, the drug may be selected from the group consisting of paclitaxel, docetaxel, and rapamycin. In any embodiments, the drug may be gefitinib-based PROTAC 3.

[0016] In another aspect, a method is provided of preparing a solid composition of any embodiment of the prior aspect, where the method includes crystalizing the composition from a liquid solution of PEG homopolymer, PEG copolymer and hydrophobic drug. In any embodiments, the temperature of the liquid solution may be from 0°C to about 50°C.

[0017] In any embodiments, the method may further include crystallizing the composition isothermally. In any embodiments, the liquid solution may include about 0.5 wt% to about 20 wt% PEG copolymer. In any embodiments, the weight ratio of PEG copolymer to drug may be from 1 : 1 to 40: 1. In any embodiments, the weight ratio of PEG copolymer to drug may be from 1 : 1 to 3 : 1. In any embodiments, the crystallization may be carried out in a glass or plastic vessel. In any embodiments, the crystallization may be carried out in a polypropylene or polyethylene vessel.

[0018] In yet another aspect, a method is provided of preparing micelles that include a hydrophobic drug, wherein the method includes dissolving the composition of any aspect or embodiment disclosed herein in an amount of water effective to provide the micelles. In any embodiments, the micelles may include about 1 wt% to about 25 wt% loaded drug. In any embodiments, the micelles may have a hydrodynamic diameter of about 10 nm to about 300 nm. In any embodiments, the micelles may have a hydrodynamic diameter of about 10 nm to about 100 nm.BRIEF DESCRIPTION OF THE DRAWINGS

[0019] FIGS. 1A-1E. FIG. 1A shows the enthalpy of fusion as a function of isothermal crystallization time for an illustrative embodiment of the present technology (i.e., PEG4kDa- b-PLA2.2kDa crystals formed at 25 °C from melt or from a 5.0 wt.% solution in PEG200- 600), and FIG. IB shows the melting onset for the same crystals. FIG. 1C shows XRD patterns of the crystals collected after isothermal crystallization from a 5.0 or 1.0 wt.% PEG4kDa-b-PLA2.2kDa in liquid PEG in glass shell vials. FIG. ID shows a graph of PTX content in crystals / PTX remaining in the PEG solution. FIG. IE shows the particle size distribution for crystals obtained from a 1.0 / 0.5 / 98.5 PEG4kDa-b-PLA2.2kDa / PTX / PEG w / w / w solution. Statistical analysis: *p < 0.05, ** p < 0.01, *** p< 0.001, ****p < 0.0001.

[0020] FIG. 2 shows the effect of the solvent PEG molecular weight and the PEG4kDa concentration on the melting onset of the crystals formed isothermally from PEG4kDa in liquid PEG solution.

[0021] FIGS. 3A-3B show the XRD spectrum of liquid PEGs (FIG. 3A) and PEG4kDa- b-PLA2,2kDa (FIG. 3B)

[0022] FIGS. 4A-4C show the effect of the cooling rate of PEG4kDa-b-PLA2.2kDa / PEG solution from 60 °C to 25 °C in borosilicate glass container on particle size distribution of the suspension obtained by hydration of the copolymer crystals for each of PEG200 (FIG. 4A), PEG400 (FIG. 4B), and PEG600 (FIG. 4C).

[0023] FIG. 5A-5E: FIG. 5A shows XRD patterns of the crystals collected after isothermal crystallization from a 5.0 or 1.0 wt.% PEG4kDa- b-PLA2.2kDa in liquid PEG in polypropylene tubes. FIG. 5B is a graph of particle size distribution and FIG. 5C shows PTX content in crystals / PTX remaining in the PEG solution for crystals obtained from a PEG4kDa-b-PLA22kDa / PTX / PEG solution with 1.0 or 0.5 wt.% copolymer and 33.0 wt.% target drug loading. FIG. 5D is a graph of PTX content and FIG. 5E shows particle size distribution of micelles produced by hydration of crystals obtained from a 1.0 / 0.5 / 98.5 PEG4kDa-b-PLA22kDa / PTX / PEG w / w / w solution as a function of isothermal crystallization time. Statistical analysis: * p < 0.05, ** p < 0.01, *** p < 0.001, **** p < 0.0001.

[0024] FIGS. 6A-6B The particle size distribution of the micelles obtained through hydration of crystals attained from a 5.0 wt.% copolymer solution is shown under isothermal crystallization at 25 °C for 24 h (FIG. 6A) or a cooling rate of 1 °C / h from 60 to 25 °C in polypropylene containers (FIG. 6B).

[0025] FIGS. 7A-7F: FIG. 7A shows laser microscopy images of crystals obtained from 1.0 wt.% PEG4kDa-b-PLA2.2kDa in PEG200 or PEG600 through isothermal crystallization at 25 °C. FIG. 7B is a schematic illustration of transformation of drug-loaded crystals into drug-loaded polymeric micelles through hydration. The effect of prolonged storage of crystals at room temperature on PTX encapsulation is shown in FIG. 7C and on particle size distribution of the micelles obtained by hydrating them in FIG. 7D. The dissolution rate of the crystals represented by PTX concentration in the supernatant is shown in FIG. 7E and the particle size distribution as a function of vortex time is shown in FIG. 7F

[0026] FIGS. 8A-8F: The effect of increasing the target loading from 33.0 wt.% (1.0 / 0.5 / 98.5 Copolymer / Drug / PEG vi’ vi’ vi’) to 50.0 wt.% (1.0 / 1.0 / 98.0 Copolymer / Drug / PEG vi’ vi’ vi’) on the loading efficiency (left column (dark) 33.0 wt.%; right column (light) 50 wt.%) is shown in FIG. 8A and on the particle size distribution (solid lines 33.0 wt.%; dashed lines 50 wt.%) in FIG. 8B, for Paclitaxel-, Rapamycin-, and Docetaxel-loaded PEG4kDa-b-PLA2.2kDa micelles made using PEG200-600 at a target drug concentration of 1 mg / mL. The effect of increasing the target drug concentration from 1 mg / mL to 5 mg / mL on the physicochemical properties of drug-loaded polymeric micelles made at 50.0 wt.% target drug loading on loading efficiency (left column: 1 mg / mL in dark; right column: 5 mg / mL in light) is shown in FIG. 8C and on particle size distribution (solid lines: 1 mg / mL; dashed lines: 5 mg / mL) is shown in FIG. 8D for Paclitaxel-, Rapamycin-, and Docetaxel-loaded PEG4kDa-b-PLA2.2kDa micelles made using PEG200-600. The effect of increasing the target drug concentration from 1 mg / mL to 5 mg / mL on the loading efficiency (left column (dark) 1 mg / mL; right column (light) 5 mg / mL) is shown in FIG. 8E and on particle size distribution (solid lines 1 mg / mL; dashed lines 5 mg / mL) in FIG. 8F for Paclitaxel-, Rapamycin-, and Docetaxel-loaded PEG4kDa-b-PLA2.2kDa micelles made using PEG200-600 at 33.0 wt.% target loading.

[0027] FIGS. 9A-9B: The effect of prolonged storage of Rapamycin (RAP)- encapsulating crystals at room temperature on encapsulation efficiency is shown in FIG. 9A and on particle size distribution of the micelles obtained by hydrating them in FIG. 9B.

[0028] FIGS. 10A-10B: The effect of prolonged storage of Docetaxel (DTX)- encapsulating crystals at room temperature on encapsulation efficiency is shown in FIG. 10A and on particle size distribution of the micelles obtained by hydrating them in FIG. 10B

[0029] FIG. 11A shows the ratiometric loading efficiency and FIG. 11B shows the unimodal particle size distribution of Paclitaxel (PTX) / Rapamycin (RAP) co-loaded micelles (33.0 wt.% total target loading) demonstrate the capability of the "crystallization from supersaturated solution" method for co-formulating drug combinations.

[0030] FIG. 12A shows the ratiometric loading efficiency and FIG. 12B shows the unimodal particle size distribution of Paclitaxel (PTX) / Rapamycin (RAP) co-loaded micelles (5 mg / mL target drug concentration) produced using the "crystallization from supersaturated solution" method.

[0031] FIGS. 13A-13F demonstrate the stability of Paclitaxel-, Rapamycin-, and Docetaxel -loaded PEG4kDa-b-PLA2.2kDa micelles (33.0 wt.% target loading) at room temperature at a 1 mg / mL target concentration.

[0032] FIGS. 14A-14F: The effect of increasing the target loading from 33.0 wt.% (1.0 / 0.5 / 98.5 Copolymer / Prodrug / PEG w / w / w) to 50.0 wt.% (1.0 / 1.0 / 98.0 Copolymer / Prodrug / PEG w / w / w) on the loading efficiency (left column (dark) 33.0 wt.%; right column (light) 50.0 wt.%) is shown in FIG. 14A and on particle size distribution (solid lines 33.0 wt.%; dashed lines 50.0 wt.%) is shown in FIG. 14B for o(LA)8-Paclitaxel-, o(LA)8-Rapamycin-, and o(LA)8-Docetaxel-loaded PEG4kDa-b-PLA2.2kDa micelles prepared using PEG200-600 at a target drug concentration of 1 mg / mL. The effect of increasing the target prodrug concentration from 1 mg / mL to 5 mg / mL on the loading efficiency (left column (dark): 1 mg / mL; right column (light): 5 mg / mL) is shown in FIG. 14C and on the particle size distribution (solid lines: 1 mg / mL; dashed lines: 5 mg / mL) in FIG. 14D for o(LA)8-Paclitaxel-, o(LA)8-Rapamycin-, and o(LA)8-Docetaxel-loaded PEG4kDa-b-PLA2.2kDa micelles made using PEG200-600 at 33.0 wt.% target loading. The effect of increasing thetarget prodrug concentration from 1 mg / mL to 5 mg / mL on the loading efficiency (left column (dark): 1 mg / mL; right column (light): 5 mg / mL) is shown in FIG. 14E and on the particle size distribution (solid lines: 1 mg / mL; dashed lines: 5 mg / mL) in FIG. 14F for o(LA)8-Paclitaxel-, o(LA)8-Rapamycin-, and o(LA)8-Docetaxel-loaded PEG4kDa-b-PLA2.2kDa micelles made using PEG200-600 at 50.0 wt.% target loading.

[0033] FIGS. 15A-15B: The stability of Paclitaxel versus o(LA)8-Paclitaxel in PEG4kDa- / 1-PLA2.2kDa micelles at room temperature at a 1 mg / mL target concentration, presented by % encapsulated drug is shown in FIG. 15A and by particle size distribution over time is shown in FIG. 15B.

[0034] FIGS. 16A-16F illustrate the stability of o(LA)8-Paclitaxel-, o(LA)8-Rapamycin- , and o(LA)8-Docetaxel -loaded PEG4kDa-b-PLA2.2kDa micelles (33.0 wt.% target loading) at room temperature at a 1 mg / mL target concentration.

[0035] FIGS. 17A-17B: The effect of prolonged storage for o(LA)8-Paclitaxel- encapsulating crystals at room temperature on encapsulation efficiency is shown in FIG. 17A and on particle size distribution of the micelles obtained by hydrating them in FIG.17B

[0036] FIGS. 18A-18B: The effect of prolonged storage for o(LA)8-Rapamycin- encapsulating crystals at room temperature on encapsulation efficiency is shown in FIG. 18A and on particle size distribution of the micelles obtained by hydrating them in FIG.18B

[0037] FIGS. 19A-19B: The effect of prolonged storage for o(LA)8-Docetaxel- encapsulating crystals at room temperature on encapsulation efficiency is shown in FIG. 19A and on particle size distribution of the micelles obtained by hydrating them in FIG.19B

[0038] FIGS. 20A-20B: The dissolution rate of the crystals, represented by % initial o(LA)8-Paclitaxel detected in the solution is shown in FIG. 20A, and on particle size distribution as a function of vortex time FIG. 20B.

[0039] FIGS. 21A-21D: The viability of 4T1 cells as a function of Paclitaxel concentration at a target loading of 33.0 wt.% is shown in FIG. 21A and at 50.0 wt.% inFIG. 20B. The viability of MDA-MB-231 cells as a function of Paclitaxel concentration at a target loading of 33.0 wt.% is shown in FIG. 21C and at 50.0 wt.% in FIG. 21D.

[0040] FIG. 22A shows the effect of loading efficiency (left column: 1 mg / mL in dark; right column: 5 mg / mL in light) and FIG. 22B shows the particle size distribution (solid lines: 1 mg / mL; dashed lines: 5 mg / mL) for Gefitinib-based PROTAC 3 loaded PEG-tkiia- / ?- PLA22kDa micelles.

[0041] FIGS. 23A-23C: The impact of increasing the PLA block molecular weight in PEG-A-PLA is shown in FIG. 23 A, that of increasing the PEG block molecular weight in PEG-A-PLA is shown in FIG. 23B, and of using other copolymers such as PEG-b-PCL and PEG-b-PS in FIG. 23C, for micelle formation using the "Crystallization from Supersaturated Solution" method.DETAILED DESCRIPTION

[0042] The following terms are used throughout as defined below.

[0043] As used herein and in the appended claims, singular articles such as “a” and “an” and “the” and similar referents in the context of describing the elements (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended merely to better illuminate the embodiments and does not pose a limitation on the scope of the claims unless otherwise stated. No language in the specification should be construed as indicating any non-claimed element as essential.

[0044] As used herein, “about” will be understood by persons of ordinary skill in the art and will vary to some extent depending upon the context in which it is used. If there are uses of the term which are not clear to persons of ordinary skill in the art, given the contextin which it is used, “about” will mean up to plus or minus 10% of the particular term - for example, “about 10 wt%” would be understood to mean “9 wt% to 11 wt% ” It is to be understood that when “about” precedes a term, the term is to be construed as disclosing “about” the term as well as the term without modification by “about” - for example, “about 10 wt%” discloses “9 wt% to 11 wt%” as well as disclosing “10 wt% ”

[0045] The phrase “and / or” as used in the present disclosure will be understood to mean any one of the recited members individually or a combination of any two or more thereof - for example, “A, B, and / or C” would mean “A or B or C; A and B; A and C; B and C; or the combination of A, B, and C.”

[0046] The present technology provides pharmaceutical compositions and medicaments comprising any of one of the embodiments of the solid compositions and micelles formed therefrom including any of the drugs and / or drug conjugates disclosed herein and a pharmaceutically acceptable carrier or one or more excipients. The compositions may be used in the methods and treatments described herein. The pharmaceutical composition may include an effective amount of any of one of the embodiments of the compounds of the present technology disclosed herein. In any of the above embodiments, the effective amount may be determined in relation to a subject. “Effective amount” refers to the amount of a compound, conjugate, micelle or composition required to produce a desired effect. One example of an effective amount includes amounts or dosages that yield acceptable toxicity and bioavailability levels for therapeutic (pharmaceutical) use including, but not limited to, the treatment of cancers..

[0047] As used herein, a “subject” or “patient” is a mammal, such as a cat, dog, rodent or primate. In any embodiments, the subject is a human, e.g., a human suffering from a cancer sensitive to any drug disclosed herein, such as a cancer capable of treatment with an effective amount of a drug disclosed herein, such as paclitaxel, docetaxel, rapamycin, everolimus, selumetinib, binimetinib, gefitinib, GDC-0623, Gefitinib-based PROTAC 3, or any other drug, derivative or conjugate described herein. The term “subject” and “patient” can be used interchangeably.

[0048] In one aspect, the present technology provides solid compositions that include a crystalline PEG copolymer, and a hydrophobic drug. Optionally, the composition also contains a PEG homopolymer. As described herein, the solid compositions may bedissolved in water to form micelles loaded with the hydrophobic drug that may then be used to administer the hydrophobic drug to a patient in need thereof.

[0049] In compositions of the present technology, the crystalline PEG copolymer may be a block copolymer and has at least one crystalline PEG block and at least one polymer block other than PEG (also referred to herein as the “non-PEG block”). For example, the crystalline PEG copolymer may be a di -block or tri -block copolymer. Because the non- PEG block is more hydrophobic than the PEG block, the crystalline PEG copolymer forms micelles in aqueous solution at or above its critical micelle concentration. The crystalline PEG block of the crystalline PEG copolymer is in crystalline form (sometimes called “semicrystalline” in the art) in the present solid compositions. The non-PEG block may be crystalline or non-crystalline, so long as the crystalline PEG copolymer may be crystallized from PEG homopolymer as described herein. Thus, suitable non-PEG blocks for the crystalline PEG copolymer include but are not limited to poly(D,L-lactic acid) (PLA), poly(s-caprolactam) (PCL), poly(lactic-co-glycolic acid), polypropylene oxide (PPO), poly(methyl methacrylate) (PMMA), poly(N-isopropylacrylamide) (PNIPAM), polystyrene, poly(L-lactic acid) (PLLA), and poly(D-lactic acid) (PDLA). Examples of crystalline PEG copolymers thus include PEG-b-PPO-b-PEG (e g., PLURONIC by BASF), PEG-b-PLGA, PEG-A-PDLLA, PEG-A-PCL, PEG-A-PCL-A-PEG, PEG-A-PMM A, PEG-A-PNIPAM, PEG- A-PCL-A-PLA, PEG-A-PS, PEG-A-PLLA, PEG-A-PDLA, PEG-A-PLA, and combinations of two or more thereof. In some embodiments of the present compositions, the crystalline PEG copolymer is PEG-b-PLA (e g., from JENKEM TECHNOLOGY) Such polymers are commercially available or may be prepared according to methods known to those of skill in the art.

[0050] In the present compositions, the molecular weight of the crystalline PEG copolymer may vary so long as the copolymer may be crystallized from PEG as described herein. Suitable molecular weights for the crystalline PEG copolymer include from about 2.5 kDa to about 50 kDa, including any increment of about 100 g / mol within said range. (All polymer molecular weights referred to herein will be understood to be weight average molecular weights.) For example, the molecular weight of the crystalline PEG copolymer may be about any of 2,500, 3,000, 3,500, 4,000, 4,200, 4,400, 4,600, 4,800, 5,000, 5,200, 5,400, 5,600, 5,800, 5,500, 6,000, 6,200, 6,400, 6,500, 7,000, 7,500, 8,000, 8,500, 9,000, 9,500, 10,000, 11,000, 12,000, 13,000, 14,000, 15,000, 16,000, 17,000, 18,000, 19,000,20,000, 21,000, 22,000, 23,000, 24,000, 25,000, 30,000, 35,000, 40,000, 45,000, 50,000 Da, or a range between and including any two of the foregoing values. Thus, in some embodiments, the molecular weight of the crystalline PEG copolymer is about 2 kDa to about 10 kDa or even about 4 kDa to about 8 kDa.

[0051] Within the crystalline PEG copolymer, the PEG block may also have various molecular weights such as about 1 kDa to about 35 kDa. For example, the molecular weight of the PEG block may be about any of 1,000, 1,500, 2,000, 2,500, 3,000, 3,500, 4,000, 4,500, 5,000, 6,000, 7,000, 8,000, 9,000, 10,000, 11,000, 12,000, 13,000, 14,000, 15,000, 16,000, 17,000, 18,000, 19,000, 20,000, 21,000, 22,000, 23,000, 24,000, 25,000, 26,000, 27,000, 28,000, 29,000, 30,000, 31,000, 32,000, 33,000, 34,000, 35,000 Da or a range between and including any two of the foregoing values.

[0052] The at least one block other than PEG (non-PEG block) may also vary in molecular weight, such as from about 1.5 kDa to about 35 kDa. For example, the molecular weight of the non-PEG block may be about any of 1,500, 2,000, 2,500, 3,000, 3,500, 4,000, 4,500, 5,000, 6,000, 7,000, 8,000, 9,000, 10,000, 11,000, 12,000, 13,000, 14,000, 15,000, 16,000, 17,000, 18,000, 19,000, 20,000, 21,000, 22,000, 23,000, 24,000, 25,000, 26,000, 27,000, 28,000, 29,000, 30,000, 31,000, 32,000, 33,000, 34,000, 35,000 Da or a range between and including any two of the foregoing values. In any embodiments, the at least one block other than PEG (non-PEG block) may include PLA having molecular weight from about 1.5 kDa to about 35 kDa. For example, the molecular weight of PLA may be about any of 1,500, 2,000, 2,500, 3,000, 3,500, 4,000, 4,500, 5,000, 6,000, 7,000, 8,000, 9,000, 10,000, 11,000, 12,000, 13,000, 14,000, 15,000, 16,000, 17,000, 18,000, 19,000, 20,000, 21,000, 22,000, 23,000, 24,000, 25,000, 26,000, 27,000, 28,000, 29,000, 30,000, 31,000, 32,000, 33,000, 34,000, 35,000 Da or a range between and including any two of the foregoing values.

[0053] In the crystalline PEG copolymer, the ratio of the molecular weight of the crystalline PEG bloc(s) to the molecular weight of the non-PEG bloc(s) may be from 15: 1 to 1 : 15. For example the ratio may be 15: 1, 14: 1, 13: 1, 12: 1, 11 : 1, 10: 1, 9: 1, 8: 1, 7: 1, 6: 1, 5: 1, 4: 1, 3: 1, 5:2, 2: 1, 3:2, 5:4, 1 : 1, 4:5, 2:3, 1 :2, 2:5, 1 :3, 1 :4, 1 :5, 1 :6, 1 :7, 1 :8, 1 :9, 1 : 10, 1 : 11, 1 : 12, 1 : 13, 1 : 14, or 1 : 15, or a range between and including any two of the foregoing values. Thus, the ratio of the molecular weight of the crystalline PEG bloc(s) to the molecularweight of the non-PEG bloc(s) in some embodiments may be from 4: 1 to 1 :4 or from 5:2 to 1 : 1. In any embdoiments, the ratio of the molecular weight of the crystalline PEG bloc(s) to the molecular weight of the non-PEG bloc(s) in some embodiments may be from 4: 1 to 1 :2 or from 5:2 to 1 : 1.

[0054] In some embodiments of the present compositions, the crystalline PEG copolymer is PEG-b-PDLLA. In some embodiments, the PEG block of PEG-b-PLA has a molecular weight of about 1.5 kDa to about 35 kDa and the PL A block may have a molecular weight of about 1.5 to about 35 kDa. In some embodiments, the PEG block has a molecular weight of about 1.5 to about 10 kDa and the PLA block has a molecular weight of about 1.5 to about 16 kDa. In some embodiments, the PEG block may have a molecular weight of about 4 kDa and the PLA block has a molecular weight of about 2.2 kDa.

[0055] The present solid compositions include a hydrophobic drug having a water solubility of <10 mg / mL at 25 °C. While not wishing to be bound by theory, it is believed that the hydrophobic drug is encapsulated in the crystalline PEG copolymer. The present compositions may include about 1 wt% to about 50 wt% hydrophobic drug by total weight of the solid composition. For example, the compositions may include about any of 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, 6 wt%, 7wt%, 8 wt%, 9 wt%, 10 wt%, 11 wt%, 12 wt%, 13 wt%, 14 wt%, 15 wt%, 20 wt%, 25 wt%, 30 wt%, 35 wt%, 40 wt%, 45 wt%, 50 wt%, or a range between and including any two or the foregoing values, by total weight of the solid composition. Thus, in some embodiments, the composition includes about 2 wt% to about 15 wt% hydrophobic drug by total weight of the solid composition.

[0056] In present compositions, the drug may be selected from the group consisting of paclitaxel, docetaxel, rapamycin, everolimus, selumetinib, binimetinib, gefitinib, GDC- 0623, ARRY-300, cabazitaxel, rapamycin, ICU 189150, doxorubicin, etoposide, 17-AAG, bicalutamide, embelin, suberoylanilide hydroxamic acid, P-lapachone, pifithrin-p, sagopilone, thiocoraline, ABT-263, podophyllotoxin, simvastatin, efavirenz, a platin prodrug, VE-822, AZD5363, teniposide, AZD8055, rutin, Gefitinib-based PROTAC 3, derivatives and / or conjugates of any of the foregoing, and combinations of two or more thereof.

[0057] Paclitaxel (also referred to as “PTX”), docetaxel (also referred to as “DTX”), rapamycin (also referred to as “RAP”), and selumetinib are potent chemotherapeutic agents useful in the treatment of a variety of cancers and have the structures shown below.Selumetinib

[0058] Derivatives of such drugs refer to analogs which retain most (e.g., > 90% on a per carbon atom basis) or all of the carbon skeleton of the drug, but includes at least one modification, e.g., on a side chain. Such derivatives also retain similar but not necessarily identical activity. Thus, as used herein, a “paclitaxel derivative” is a compound that retains the carbocyclic / oxetane skeleton of paclitaxel (z.e., the taxane skeleton) but contains at least one modified side chain. In any embodiments, the modified side chain is other than the 7- hydroxyl. Paclitaxel derivatives of the present technology exhibit anti-cancer activity. For example, docetaxel is a paclitaxel derivative which contains a modification of the C-13 sidechain in which t-butyloxy carbonylamino replaces benzamido at the 3 ’-position. Other paclitaxel derivatives are known to those of skill in the art and include but are not limited to those described in Farina, V., “The chemistry and pharmacology of Taxol and itsderivatives,” Elsevier, New York, 1995 (incorporated herein by reference in its entirety and for all purposes).

[0059] As used herein, a “rapamycin derivative” or “rapalog” is a compound that retains the macrocyclic lactone ring of rapamycin, but contains at least one modified side chain while retaining a free hydroxyl group on the C-40 position or a free hydroxyl attached to a modified side chain bonded to the C-40 position (e.g., everolimus). Rapamycin derivatives of the present technology exhibit anti-cancer activity. For example, everolimus is a rapamycin derivative with the structure below. Other rapamycin derivatives are known to those of skill in the art and include but are not limited to those described in Wander, S., et al., “Next-generation mTOR inhibitors in clinical oncology: how pathway complexity informs therapeutic strategy,” J. Clin. Invest., 121(4), 1231-1241 (2011) (incorporated herein by reference).everolimus

[0060] As used herein, a “selumetinib derivative” is a compound that retains the 6,5- fused ring system of selumetinib, but contains at least one modified side chain while retaining a free hydroxyl group on the C-2’ position (e.g., binimetinib, GDC-0623, and ARRY-300). Selumetinib derivatives of the present technology exhibit anti -cancer activity. For example, binimetinib and GDC-0623 are selumetinib derivatives with the structures below. Other selumetinib derivatives are known to those of skill in the art and include but are not limited to those described in Jokinen, E., et al., “MEK and PI3K inhibition in solidtumors: rationale and evidence to date,” Ther. Adv. Med. Oncol., 7(3), 170-180 (2015) (incorporated herein by reference).

[0061] PROTAC (proteolysis targeting chimera) is a heterobifunctional molecule composed of two active domains and a linker, capable of removing specific unwanted proteins. In some embodiments, the PROTAC described herein is Gefitinib-based PROTAC3.Gefitinib-based PROTAC3

[0062] In any embodiments, the drug may be an oligolactic acid conjugate. Such conjugates are known in the art and described in, e.g., WO2017 / 158499 and WO2019 / 195164, the entire contents of which are incorporated herein by reference and for all purposes. In any embodiments, the drug conjugate may be 7-oligolactic acid conjugate of paclitaxel or a paclitaxel derivative (e.g., docetaxel) wherein the oligolactic acid comprises 2 to 24 lactic acid subunits (e.g., 8 lactic acid subunits, also referred to as“oLAs”) and is attached through an ester linkage to the oxygen of the 7-hydroxyl of the paclitaxel or paclitaxel derivative (e.g., docetaxel); a 40-oligolactic acid conjugate of rapamycin or a rapamycin derivative wherein the oligolactic acid comprises 2 to 24 lactic acid subunits (e.g., 8 lactic acid subunits) and is attached through an ester linkage to the oxygen of the 40-hydroxyl of the rapamycin or rapamycin derivative; and / or a 2’ -oligolactic acid conjugate of selumetinib or a selumetinib derivative wherein the oligolactic acid comprises 2 to 24 lactic acid subunits and is attached through an ester linkage to the oxygen of the 2’ -hydroxyl of the selumetinib or selumetinib derivative.

[0063] The present compositions optionally include a PEG homopolymer having a molecular weight of about 200 Da to about 800 Da, e.g., about 200, 300, 400, 500, 600, 700, 800, or a range between and including any two of the foregoing values. In some embodiments, the PEG homopolymer has a molecular weight of about 200 to about 600 Da. In some embodiments, the PEG homopolymer has a molecular weight of about 400 to about 600 Da. In some embodiments, the PEG homopolymer includes up to 10 wt% of the composition, e.g., 0.01 wt%, 0.05 wt%, 0.1 wt%, 0.5 wt%, 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, 10 wt%, or a range between and including any two of the forgoing values. In some embodiments, the PEG homopolymer includes 0.01 wt% to 5 wt% or to 10 wt%.

[0064] In another aspect, the present technology provides methods of preparing any of the solid compositions described herein where the method includes crystalizing the composition from a liquid solution of PEG homopolymer, a PEG copolymer (i.e., the crystalline PEG copolymer prior to crystallization), and hydrophobic drug. The PEG homopolymer, PEG copolymer, and hydrophobic drug may be any of those described herein. In some embodiments, the method includes dissolving the PEG copolymer and hydrophobic drug in the PEG homopolymer. The temperature of the liquid solution may need to be elevated above room temperature to achieve such dissolution. For example, the temperature may need to be about 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, or higher depending on the PEG copolymer used. The temperature may be a range between and including any two of the foregoing values. In some embodiments the liquid solution may be heated to a temperature sufficiently high for a period of time to “erase” the thermal history of the solution, e.g., to about 80°C for at least 5, at least 10, at least 15, or at least 30 minutes or more.

[0065] Crystallization may be accomplished by cooling the liquid solution to achieve a supersaturated solution from which the solid compositions will form. The crystallization may be isothermal, e.g., isothermal at a temperature from 0°C to about 50°C (including any temperature within that range in 1°C degree increments). Alternatively, the liquid solution may be slowly but continuously cooled from a first temperature (non-supersaturated solution of PEG copolymer) to one or more second temperatures where the solution becomes supersaturated. The cooling rate may be anywhere from 0.01°C or 0.1°C / minute to about 5°C / minute. The second temperature may be any suitable temperature where the PEG homopolymer used remains liquid. The crystallization may be carried out in any suitable vessel, including glass or plastic, e.g., a polypropylene or polyethylene vessel.

[0066] In some embodiments of the method, the liquid solution includes about 0.5 wt% to about 20 wt% PEG copolymer, e.g., about 0.5 wt%, 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, 10 wt%, 11 wt%, 12 wt%, 13 wt%, 14 wt%, 15 wt%, 16 wt%, 17 wt%, 18 wt%, 19 wt%, 20 wt% PEG copolymer or a range between and including any two of the foregoing values. In some embodiments, the weight ratio of PEG copolymer to drug is from 1 : 1 to 40: 1, e.g., 1 : 1, 3:2, 2: 1, 3: 1, 4: 1, 5: 1, 10: 1, 15: 1, 20: 1, 30: 1, 40: 1 or a range between and including any two of the foregoing values. For example, in some embodiments, the weight ratio of PEG copolymer to drug is from 1 : 1 to 3 : 1. Various amounts of the drug may be used to prepare the drug-loaded micelles. In any embodiments, the non-saturated solution may include 0.005 wt% to 50 wt% drug. For example, the non-saturated solution may include 0.005 wt%, 0.01 wt%, 0.05 wt%, 0.1 wt%, 0.2 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt%, 0.75 wt%, 1 wt%, 1.5 wt%, 2 wt%, 2.5 wt%, 3 wt%, 3.5 wt%, 4 wt%, 4.5 wt%, 5 wt%, 5.5 wt%, 6 wt%, 6.5 wt%, 7 wt%, 7.5 wt%, 8 wt%, 9 wt%, 10 wt%, 11 wt%, 12, wt% 13 wt%, 14 wt%, 15 wt%, 16 wt%, 17 wt%, 18 wt%, 19 wt%, 20 wt%, 25 wt%, 30 wt%, 35 wt%, 40 wt%, 45 wt%, 50 wt% or a range between and including any two of the foregoing values. For example, the non-saturated solution may include 0.05 wt% to 5 wt% or to 10 wt% drug.

[0067] In yet another aspect, the present technology provides methods of preparing micelles comprising a hydrophobic drug, wherein the methods include dissolving a composition as described herein in an amount of water effective to provide the micelles. That is, the amount of water must be such that the critical micelle concentration for the crystalline PEG copolymer is reached. In some embodiments, the resulting micelles includeabout 1 wt% to about 25 wt% loaded drug, e.g., about 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, 10 wt%, 15 wt%, 20 wt%, 25 wt%, or a range between and including any two of the foregoing values. In some embodiments of the method, the micelles have a hydrodynamic diameter of about 10 nm to about 300 nm, e.g., about 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 125, 150, 175, 200, 225, 250, 275, 300 nm or a range between and including any two of the foregoing values. Thus, in some embodiments, of the methods, the micelles have a hydrodynamic diameter of about 10 nm to about 100 nm.EXAMPLESMaterials and General Methods

[0068] Polyethylene glycol-b-poly(DL-lactide) (PEG-b-PLA, PEG block Mw: 4 kDa, PDLLA block Mw: 2.2 kDa) diblock copolymer was purchased from JenKem Technology (Plano, TX). Different molecular weight PEGs (200, 400, 600, and 4000 Da) were purchased from Sigma-Aldrich (St. Louis, MO). Paclitaxel, Rapamycin and Docetaxel were acquired from LC Laboratories (Woburn, MA). oligo(lactic acid)8-Paclitaxel, oligo(lactic acid)s- Rapamycin and oligo(lactic acid)8-Docetaxel were synthesized by Genesis Drug Discovery and Development (Hamilton, NJ) according to our previously published protocols.

[0069] Isothermal crystallization kinetics and crystalline structure of PEG-6-PLA.The isothermal crystallization kinetics of PEG4kDa-b-PLA2.2kDa from supersaturated solutions of the copolymer in low molecular weight PEG at room temperature was studied using differential scanning calorimetry (DSC 404 Fl Pegasus, NETZSCH, Germany). Briefly, diblock copolymer granules (5.0 wt.%) were added to liquid PEG (Mw 200-600 Da), heated to 60 °C and vortex-shaken to obtain a transparent mixture. The mixture was incubated at 60 °C for 1 h before being transferred to aluminum crucibles. The thermal history of the samples was erased by 15 min isothermal hold at 80 °C. The isothermal crystallization was then performed by cooling the samples to 25 °C and isothermal hold for various periods ranging from 0.5 to 48 h. The samples were finally heated to 80 °C in the second scan to measure the melting onset temperature and enthalpy. A heating / cooling rate of 5 °C / min was used for all the scans.

[0070] To study the crystalline structure, PEG4kDa-b-PLA2.2kDa crystals were prepared by isothermal crystallization from solution and analyzed using powder X-ray diffraction (PXRD). Briefly, a 5.0 or 1.0 wt.% PEG4kDa-b-PLA2.2kDa solution in PEG200-600 Da was prepared by heating the mixture to 60 °C vortexing and incubation for 1 h. Isothermal crystallization was conducted by transferring the samples to 25 °C in borosilicate glass or syndiotactic polypropylene containers and incubating for 72 h. The crystals were collected through centrifugation at 16000 g for 30 min and analyzed using PXRD (Bruker D8 Advance diffractometer with a Cu Ka source, A = 1.54178 A). The diffraction patterns were collected at 29 between 10-40° at a scanning rate of 57min.

[0071] Laser microscopy (LEXT OLS4000, Olympus, Japan) was used to image the morphology of the crystals in the solution.

[0072] Preparation and characterization of drug-loaded crystals and micelles. To prepare drug-loaded crystals, PTX was added to PEG-b-PLA solution in liquid PEG prior to crystallization. PEG4kDa-b-PLA2.2kDa / PTX / PEG at 1.0 or 0.5 wt.% copolymer concentration and 33.0 wt.% PTX target loading (1.00 / 0.50 / 98.50 or 0.50 / 0.25 / 99.25 copolymer / PTX / PEG w / w / w) was heated to 60 °C and vortexed to obtain a transparent mixture. After 1 h of incubation at 60 °C, the samples were transferred to 25 °C in glass shell vials or syndiotactic polypropylene microtubes and allowed to crystallize isothermally for up to 72 h. The crystals were separated via centrifugation at 16000 g for 30 min after isothermal crystallization at 25 °C and analyzed.

[0073] The PTX content in the crystals was measured through a direct or indirect method utilizing high-performance liquid chromatography (HPLC, Prominence, Shimadzu, Japan) equipped with an autosampler, a C18 column and a UV-Vis detector. In the direct method, crystals were dissolved in acetonitrile (ACN) and analyzed. PTX was detected at 228 nm absorption wavelength following injection of 10 pL sample using a 70 / 30 v / v ACN / water mixture as the mobile phase at a flow rate of 1 mL / min. The same procedure was repeated for the supernatant to obtain the ratio of PTX loaded into the crystals and of that remaining in the solution. In the indirect method, crystals were first hydrated to obtain drug-loaded particles at a target PTX concentration of 1 mg / mL considering the initial amount of PTX in the PEG solution. The samples were then analyzed for PTX content and particle size distribution. To measure PTX content, the unencapsulated drug was firstremoved by centrifugation at 10000g for 10 min. Following centrifugation, 50 pL of the supernatant of each sample was analyzed using HPLC. Dynamic light scattering (DLS, nano ZS, Malvern) was used to measure particle size distribution. The measurements were carried out at 25 °C using water as the dispersant.

[0074] The following parameters were frequently calculated / measured for different samples when a drug was present in the mixture:

[0075] The impact of isothermal crystallization period on the Paclitaxel loading efficiency and particle size distribution of micelles was investigated by collecting the PEG4kDa-b-PLA2.2kDa crystals at different time points ranging from 1 to 72 h, followed by hydration and analysis. The feasibility of long-term storage of crystals and its impact on the resulting micelles were evaluated by producing Paclitaxel-loaded PEG4kDa-b-PLA2.2kDa crystals from solution, followed by storing the crystals for 0, 15, or 30 days at room temperature, then hydrating them and analyzing the Paclitaxel loading efficiency and particle size distribution of the resulting micelles. The dissolution rate of Paclitaxel-loaded PEG4kDa- b-PLA2.2kDa crystals or the rate of their transformation to drug-loaded polymeric micelles was investigated by adding water followed by vortexing for 1, 5, 10, or 15 seconds and measuring both particle size distribution and Paclitaxel concentration in the solution.

[0076] The effects of payload, target drug loading, and target drug concentration were also examined. Paclitaxel, Rapamycin, Docetaxel, or their oligolactic acid-conjugated o(LA)s-prodrugs were incorporated into a PEG4kDa-b-PLA2.2kDa / PEG mixture at a copolymer concentration of 1.0 wt.% and drug / copolymer ratios of 1 :2 or 1 : 1 w / w, aiming for 33.0 or 50.0 wt.% target drug loading, respectively. The samples were heated to 60 °C and vortexed to obtain a transparent mixture. Following 1 hour of incubation at 60 °C, the samples were cooled to 25 °C and allowed to crystallize isothermally for up to 72 hours. The resulting crystals were separated via centrifugation at 10000 g for 20 minutes following isothermal crystallization at 25 °C. Drug-loaded polymeric micelles were then obtained by hydrating the crystals at target drug concentrations of 1 or 5 mg / mL and subsequently analyzed for loadingefficiency, particle size distribution, and stability over time. The feasibility of long-term storage of the crystals and their dissolution rate were measured for selected samples according to the protocol mentioned above. Stability was assessed by monitoring the particle size distribution and drug leakage over a 24-hour period.

[0077] To evaluate the capacity of crystals to encapsulate a combination of two drugs while preserving the initial feed ratio in the resulting micelles, Paclitaxel and Rapamycin were co-loaded into PEG4kDa-b-PLA2.2kDa at Paclitaxel / Rapamycin w / w ratios of 2: 1, 1 : 1, or 1 :2, targeting a total drug loading of 33.0 wt.%, following the same protocol described earlier. The crystals were subsequently hydrated at target drug concentrations of 1 or 5 mg / mL and analyzed for their properties.

[0078] Cell Culture and Cytotoxicity Assay

[0079] 4T1 and MDA-MB-231 cells (3* 10A4 cells / mL, 100 pL) were obtained fromAmerican Type Culture Collection (ATCC) and seeded in a 96-well plate and incubated for 24 hours at 37 °C. The cells were then treated with Paclitaxel-loaded PEG4kDa-b-PLA2.2kDa micelles prepared by crystallization from supersaturated solutions of PEG200, PEG400, or PEG600, followed by a further 72-hour incubation at 37 °C. After incubation, cell viability was evaluated using the CellTiter-Blue assay (Promega, Madison, WI).

[0080] Statistical analysis. All the measurements are reported as mean ± SD. One-way ANOVA was used to analyze statistical differences between different groups followed by Tukey’s Honest Significant Difference (HSD) as a multiple comparison test. The differences were considered significant if p < 0.05.Example 1 - PEG-6-PLA can encapsulate drug in solid form when crystallized out of a supersaturated solution

[0081] Cooling of a 5.0 wt.% PEG4kDa-b-PLA2.2kDa in liquid PEG (200-600 Da) mixture to room temperature causes turbidity over time and results in a waxy solid as a result of crystallization of the PEG block of the copolymer at reduced temperatures. In other words, a 5.0 wt.% PEG4kDa-b-PLA2.2kDa in liquid PEG attains supersaturation at 25 °C. Here, it was shown that the crystals can encapsulate a significant amount of the drug when theyprecipitate out of the solution at a temperature below the crystallization temperature of the PEG-A-PLA.

[0082] The kinetics of crystallization of PEG4kDa-b-PLA2.2kDa highly depends on the molecular weight of the PEG used as the solvent. FIG. 1A demonstrates the enthalpy of fusion as a function of the isothermal crystallization time for copolymer crystals formed at 25 °C from melt or from a 5.0 wt.% solution in PEG200, PEG400 or PEG600. To collect this data, the samples are heated above the melting point of the copolymer followed by isothermal crystallization at 25 °C. The enthalpy of fusion and the melting onset of the resulting crystals are then measured in the next heating cycle. According to the collected data, the crystallization rate is inversely proportional to the molecular weight of the solvent PEG. If a sufficient duration of crystallization is allowed, the major fraction of copolymer chains crystallizes out of the solution. This is confirmed by the comparable enthalpy of fusion of the copolymer crystallized from the solution and that of crystallization from the melt.

[0083] FIG. IB displays the effect of the molecular weight of the solvent PEG on the melting onset of the crystals formed isothermally from a 5.0 wt.% PEG4kDa-b-PLA2.2kDa in liquid PEG solution. As seen, the lower the molecular weight of the solvent PEG, the lower the melting onset of the resulting crystals from the corresponding solution. The melting onset of the copolymer crystallized from the melt was recorded as 48.3 ± 0.1 °C which is slightly lower than the measured value for PEG4kDa homopolymer i.e. 51.6 ± 1.4 °C (see FIG. 2). The presence of amorphous PLA blocks may limit the diffusion of the copolymer chains and suppress crystallization as previously reported. The crystallization from PEG600, PEG400, and PEG200 solutions yields crystals with melting onset equal to 42.7 ± 0.6, 36.5 ± 0.8 and 33.0 ± 0.4 °C, respectively. The depression of the melting point of the crystals obtained from the solution suggests the possibility of incorporation of low molecular weight PEG into the formed solid structures and / or altered crystal size as a result of differences in crystallization kinetics. A very similar trend but at higher temperatures is observed for different concentrations of PEG4kDa homopolymer in liquid PEG (see FIG. 2) suggesting the notable impact of the molecular weight of solvent PEG and the presence of PLA block on the structure and properties of the copolymer crystals obtained from solution.

[0084] XRD analysis was used to study the structure of these crystals. The crystals were collected via centrifugation after isothermal crystallization from a 5.0 or 1.0 wt.% PEG4kDa- b-PLA2.2kDa in liquid PEG in glass shell vials for 72 h. Pure liquid PEG was used as the control for each measurement (see FIGS. 3A-3B). The XRD patterns of all the crystals obtained from the 5.0 wt.% solution (FIG. 1C) showed two distinct diffraction peaks at 19.6° and 23.4° agreeing with the interplanar spacing of 4.65 A and 3.82 A, respectively. These two peaks represent (120) and (032) crystal plane diffraction of PEG, respectively, and distinctly appear in the spectrum of PEG-b-PLA crystallized from the melt as well (see FIGS. 3A-3B) The XRD pattern for crystals obtained from the PEG600 solution was slightly different from lower molecular weight solvent PEGs by exhibiting two minor peaks at 32.6° and 36.3°. These peaks have been previously reported for PEG crystals. These two peaks are present in the spectrum of PEG-A-PLA crystallized from the melt as well (see FIGS. 3A-3B). The major diffraction peaks remained consistent in the XRD patterns of the crystals obtained from the 1.0 wt.% solution when incubated in syndiotactic polypropylene containers (FIG. 1C). The variations in intensity, sharpness, and position of the peaks suggest differences in crystal structure which in turn may lead to differences in the properties of those crystals.

[0085] To investigate whether the obtained crystals can encapsulate the drug when precipitating out of the solution, 72 h isothermal crystallization was performed at 25 °C while PTX was present in the solution. The crystallization for PEG4kDa-b- PLA2.2kDa / PTX / PEG was conducted at 1.0 wt.% copolymer concentration and 33.0 wt.% PTX target loading (1.0 / 0.5 / 98.5 copolymer / PTX / PEG w / w / w) in glass shell vials and separated the crystals via centrifugation at 16000 g for 30 min. The rationale for using 1.0 wt.% copolymer was the formation of discrete crystals that were easily separable by centrifugation. Crystallization of higher concentrations produces a waxy solid or gel-like body wherein the two phases are not easily distinguishable and separable. Incomplete separation of the two phases may introduce substantial errors in the measurement of the quantity of the encapsulated PTX. However, slower kinetics of crystallization for 1.0 wt.% mixtures prolonged the crystallization process to obtain adequate crystal content. The PTX content in both crystals and supernatant was measured using HPLC. As demonstrated in FIG. ID, the PTX entrapped in crystals is 24.7 ± 1.7 %w / w of the PTX found in supernatant for PEG200 solution, 13.5 ± 1.5 %w / w for PEG400 and 10.4 ± 2.1 %w / w for PEG600.Considering the 1.0 wt.% copolymer content compared to the 98.5 wt.% liquid PEG, it can be concluded that PTX has a high propensity to partition into the formed crystals rather than remaining in the solution. The loading content for PTX entrapped in crystals obtained from 1.0 wt.% copolymer in PEG200, PEG400 and PEG600 solutions is at least 9.0 ± 0.4, 5.6 ± 0.5 and 4.5 ± 0.8 wt.%, respectively. It should be noted that while the crystallizable PEG block in PEG-b-PLA might not be well receptive of impurities, the PLA block remains amorphous and is capable of entrapping PTX. The crystal-entrapped to supernatant PTX ratio has an inverse relationship with PEG molecular weight perhaps due to the lower crystal content as a result of slower crystallization in higher molecular weight PEGs. Oneway ANOVA suggests that the effect of PEG molecular weight on this ratio is extremely significant (p < 0.0001).

[0086] It was investigated whether these PTX-loaded crystals can produce micellar PTX once hydrated. The size distribution of the particles obtained by hydration of the crystals was analyzed. The obtained crystals rapidly dissolve in water. PEG4kDa-b-PLA2.2kDa used in this study is expected to produce 25-50 nm PTX-encapsulated micelles depending on the preparation process. As seen in FIG. IE, depending on the solvent PEG molecular weight, the hydration of crystals yields a unimodal distribution of large particles, or a bimodal distribution composed of both polymeric micelles and larger particles. In other words, for all PEG molecular weights, a notable fraction of formed particles is >100 nm in size. The presence of PTX-loaded polymeric micelles in the samples obtained by hydration of the PEG400 and PEG600 derived crystals convinced us that a uniform micellar solution might be achievable under specific crystallization conditions. Subsequently, the impact of cooling rate and the nature of inner wall of the container on the outcome of particle size distribution was examined.Example 2 - PEG-6-PLA crystals can produce drug-loaded polymeric micelles upon hydration

[0087] First, the impact of the cooling rate of PEG4kDa-b-PLA2.2kDa / PEG solution from 60 °C to 25 °C on particle size distribution of the suspension obtained by hydration of PEG4kDa-b-PLA2.2kDa crystal s was investigated (see FIGS. 4A-4C). The cooling rate is a well-known variable that impacts the crystallization process mainly by altering the degree of crystallinity, crystal size and melting point. None of the examined cooling rates rangingfrom 1 to 60 °C / h yielded a uniform micellar solution. Particles of >100 nm in size appeared in the hydrated sample regardless of the solvent PEG molecular weight and the cooling rate. For most samples, polymeric micelles co-existed with these large particles which led us to believe that these two different types of nanoparticles are derived from two different solid sources.

[0088] Next, the impact of the nature of the inner wall of the solution container on particle size distribution of the suspension obtained by hydration of PEG4kDa-b-PLA2.2kDa crystals was investigated. The impact of a foreign surface on the crystallization kinetics and the resultant crystal structure and morphology is very well documented. For instance, the presence of heterogeneous surfaces can alter crystallization rate by changing the nucleation rate - especially for polymers with difficulty in homogeneous nucleation. This may result in the formation of crystals with different properties as the result of variation in crystallization process. The container was changed from borosilicate glass to syndiotactic polypropylene. The same procedure was repeated for separation of the crystals. The XRD patterns of all the crystals obtained from the 5.0 wt.% solution (FIG. 5A) showed the two diffraction peaks at 19.6° and 23.4° representing (120) and (032) crystal plane diffractions of PEG, respectively. Interestingly, the minor peak at 36.3° appeared in the XRD pattern of the crystals obtained from all molecular weight PEG solutions. In contrast to the samples prepared in borosilicate glass shell vials, the major diffraction peaks neither attenuated significantly nor disappeared in the XRD patterns of the crystals obtained from 1.0 wt.% solution when incubated in syndiotactic polypropylene containers (FIG. 5A). Furthermore, hydration of the crystals produced in polypropylene container from PEG4kDa-b-PLA2.2kDa / PTX / PEG solution (1.0 / 0.5 / 98.5 copolymer / PTX / PEG w / w / w) resulted in the formation of uniform drug- loaded polymeric micelles almost for all molecular weights of solvent PEG (FIG. 5B). When PEG200 is used as the solvent in crystallization, the resultant sample still presents a negligible peak for larger particles when hydrated. However, crystals obtained from higher molecular weights of solvent PEG yield a uniform dispersion of drug-loaded polymeric micelles. The effect of lowering the initial concentration of the copolymer from 1.0 to 0.5 wt.% on the particle size distribution of the hydrated sample was investigated and a uniform dispersion of approximately 30-40 nm micelles was still obtained for all molecular weights of the solvent PEG as displayed in FIG. 5B. When polypropylene is used for crystallization, polymeric micelles form as the dominant species even if the copolymer concentration or thecooling rate are altered significantly (see FIGS. 6A-6B). It was concluded that the nature of the inner wall plays a crucial role in the outcome of crystallization and the resulting particles obtained by hydration of those crystals.

[0089] As previously mentioned, the larger particles and polymeric micelles may be derived from two different solid sources. Recalling the XRD results (FIG. 5A), the major diffraction peaks of the crystals obtained from 1.0 wt.% solution remain unchanged when the crystallization is conducted in polypropylene containers. These crystals mainly produce uniform micelles. In contrast, using glass containers for crystallization leads to attenuated diffraction peaks and suppresses micelle formation. The combined evidence suggests that the micellar phase dominates when the collected solid consists of a highly crystalline structure.

[0090] To confirm that the PTX-loaded crystals transform into PTX-loaded polymeric micelles without drug loss, the PTX content in the polymeric micelles obtained by hydration of the crystals (indirect method) was measured and compared it with the PTX content obtained by directly dissolving the crystals in acetonitrile (direct method). As shown in FIG. 5C, for 1.0 wt.% PEG4kDa-b-PLA2.2kDa in PEG, the PTX content in the crystals obtained by the indirect method was found to be 29.2 ± 1.4, 11.0 ± 1.8 and 12.8 ± 0.6 %w / w when PEG200-600 were used as the solvent, respectively. These values are closely comparable to the ones previously obtained using the direct method. For 0.5 wt.% PEG4kDa- b-PLA2.2kDa in PEG solution, the PTX content in the crystals measured by the direct vs. the indirect method was 16.8 ± 0.1 vs. 18.9 ± 0.5, 4.7 ± 0.0 vs. 5.5 ± 0.2 and 9.4 ± 0.0 vs. 9.3 ± 1.4 ° / ow / w when PEG200-600 were used as the solvent, respectively (FIG. 5C). No significant difference (p > 0.05) was found between PTX content measured by the direct vs. the indirect method for any of the examined solvent PEGs suggesting that PTX-loaded crystals can transform into PTX-loaded polymeric micelles without drug loss. These observations are consistent with PTX as loaded into the amorphous PLA block of the copolymer.

[0091] Another important observation throughout the study was the higher PTX content of the samples obtained from PEG200. The higher PTX content in those samples was attributed to the kinetics of crystallization of the copolymer in PEG solution. To further investigate this hypothesis, a time-dependent PTX encapsulation experiment was conducted.PEG4kDa-b-PLA2.2kDa / PTX / PEG solution (1.0 / 0.5 / 98.5 copolymer / PTX / PEG w / w / w) was allowed to undergo isothermal crystallization at 25 °C. At different time points, the crystals were separated, hydrated at a target concentration of 1.0 mg / mL PTX and analyzed for PTX content and particle size distribution. The kinetics of PTX encapsulation (FIG. 5D) is very similar to the kinetics of the crystallization of the copolymer from solution (FIG. 1A). Polymeric micelles form the dominant phase for all the samples at every time point (FIG. 5E). The particle size distribution is unimodal for all samples except for a few time points in the PEG200 sample. The percentage encapsulated PTX reaches a plateau for all solvent PEGs after almost 24 h (FIG. 5D) which is in agreement to near-zero crystallization rate after this time point (FIG. 1A). The percentage encapsulated PTX reaches ~25 %w / w for micelles formed by PEG200 solution crystals and ~10 %w / w for micelles formed by PEG400 or PEG600 solution crystals at prolonged times which are consistent with the values previously measured for PTX content of the crystals. The higher rate of PTX encapsulation in the micelles obtained from PEG200 solution-derived crystals can be attributed to the faster crystallization kinetics. PEG200 solution produces a higher crystal content compared to PEG400 and 600. Similarly, PEG400-derived crystals and the resulting micelles are expected to present a higher rate of PTX encapsulation compared to PEG600-derived crystals and the corresponding micelles but as seen in FIG. 5D, both the rate of encapsulation and the final PTX content are comparable for micelles obtained by hydration of PEG400 and 600-derived crystals. It is posited that the difference in solubility of PTX in PEG400 vs. PEG600 may lead to such an observation. Higher solubility of PTX in PEG400 compared to PEG600, reduces its partitioning into the crystals. Therefore, a tradeoff between the crystallization kinetics / crystal content and PTX solubility in the solvent PEG determined the rate of encapsulation and the final PTX content is suggested. The lower the molecular weight of the solvent PEG, the faster the crystallization but also the lower the propensity of PTX to partition into the formed crystals.Example 3 - Morphology, long-term storage, and dissolution rate of the crystals

[0092] The macroscopic morphology of the obtained crystals. Polymer crystals display ordering at a variety of dimensional levels from interatomic spacings to macroscopic levels was investigated. Despite similar crystal structures confirmed by XRD patterns, crystals obtained from copolymer solutions in different PEGs revealed some differences. FIG. 7A demonstrates the laser microscope images of crystals obtained from 1.0 wt.% PEG4kDa-b-PLA2.2kDa in PEG200 or PEG600 through isothermal crystallization at 25 °C. The formation of banded spherulites is evident for both types of crystals. However, the slower kinetics of crystallization in PEG600 solution allows the uniform growth of spherulites in all directions while the crystals obtained from PEG200 exhibit an arbitrary growth. The formation of banded spherulites has been previously reported for different homopolymer and block copolymers. The formation of those banded spherulites is thought to originate from a periodic change of radial lamellar orientation or a discrete radial lamellar packing.

[0093] The system in the present study is a blend of PEG-b-PLA and low molecular weight PEGs. Overall, DSC, XRD, and microscopy confirmed the crystallization of the PEG block in the PEG-b-PLA copolymer from a blend of PEG-A-PLA and low molecular weight PEGs. Higher-order structure of crystalline block copolymers or polymer blends has been suggested to form by the interplay between two kinds of phase transitions: crystallization, and liquid-liquid phase separation (LLPS). In the case of polymer blends, crystallization-induced LLPS and LLPS-induced crystallization might occur kinetically during the structure formation. In this case, the amorphous component such as solvent PEG can either be excluded from or included in the inter-crystalline lamellar region depending on the competition between the crystallization and molecular diffusion rates. The restriction on chain mobility by tethered PEG chains bonded by amorphous PDLLA blocks has been suggested to play a key role in the crystallization and thermal behavior of PEG in PEG-b-PLA. The connectivity of amorphous PDLLA chains can significantly lower the crystallization rate of the PEG block.

[0094] The combined evidence suggests that crystallization of PEG-b-PLA in an oligomer PEG solution, containing a drug such as PTX, produces drug-loaded crystals that can transform to drug-loaded polymeric micelles once hydrated as schematically illustrated in FIG. 7B. The described method, hereafter referred to as "crystallization from supersaturated solution," can be utilized for the production of drug-containing crystals, which can be stored long-term and subsequently converted into drug-loaded polymeric micelles upon hydration and slight agitation.

[0095] Dissolving a copolymer in a non-selective solvent (e.g. acetonitrile) followed by replacement with or addition of a selective solvent (e.g. water) constructs the basis of most fabrication methods for polymeric micelles. Addition of drugs to the initial copolymer solutions results in drug encapsulation during self-assembly. The current approach forformulating drug-loaded polymeric micelles is to produce an aqueous suspension, then transform it to a solid form through lyophilization for long-term storage. Rehydration of this solid form produces drug-loaded polymeric micelles prior to administration. Current methods for fabrication of drug-loaded polymeric micelles involve the utilization of toxic organic solvents, complex procedures, and specialized equipment which present technical, safety, environmental, and economic challenges during production. Regulatory concerns such as residual solvent and the reproducibility of nanoscale properties are additional issues that determine the successful marketing of a nanomedicine. The crystals obtained from supersaturated solution of copolymer in liquid PEG can be considered as a safe alternate solid form to lyophilization. Therefore, the impact of long-term storage of these crystals on the properties of the resulted micelles next was investigated. Crystals obtained from PEG-tkiia- / ?- PLA2.2kDa / PTX / PEG solution (1.0 / 0.5 / 98.5 copolymer / PTX / PEG w / w / w) were stored at room temperature for 0, 15 or 30 days and then hydrated at a target PTX concentration of 1 mg / mL considering the initial amount of PTX in the solution. Storing the crystals for 15 or 30 days led no significant difference (p > 0.05) in encapsulated PTX (FIG. 7C) and particle size distribution (FIG. 7D) compared to day 0. The dissolution rate of these crystals by vortexagitating them in water at 5 s intervals and measuring the PTX concentration in the solution and monitoring the formation of polymeric micelles was also probed. As seen in FIG. 7E, the PTX concentration reaches a plateau after 5 s of agitation demonstrating the high dissolution rate of these crystals in water. The final concentration of PTX i.e. ~0.2 mg / mL for PEG200 and -0.1 mg / mL for PEG400 and 600 matches the expected values considering the target PTX concentration of 1 mg / mL and PTX encapsulation capability of the crystals (FIG. 5C). Particle size distribution analysis shows that 5s agitation results in formation of uniform polymeric micelles (FIG. 7F).Example 4 - Loading of various drugs into polymeric micelles at different target loadings and drug concentrations

[0096] The capability of the "crystallization from supersaturated solution" method to encapsulate different drugs in polymeric micelles was investigated under various conditions and formulation parameters. Specifically, the impact of increasing the target drug loading and target drug concentration in the aqueous medium after dissolution of the crystals on the properties of the micelles produced was studied using Paclitaxel, Rapamycin, and Docetaxel as model drugs.

[0097] First, while maintaining the PEG4kDa- ’-PLA2.2kDa concentration in PEG200-600 at 1.0 wt.%, the target loading was increased from 33.0 wt.% (1.0 / 0.5 / 98.5Copolymer / Drug / PEG w / w / w) to 50.0 wt.% (1.0 / 1.0 / 98.0 Copolymer / Drug / PEG w / w / w) and hydrated the crystals, aiming for a 1 mg / mL drug concentration in the aqueous medium. As shown in FIG. 8A, increasing the target loading in the initial supersaturated solution led to a proportional increase in the amount of drug encapsulated in the resulting polymeric micelles. For instance, using PEG200, when the target loading was increased from 33.0 wt.% to 50.0 wt.% (a 1.5-fold increase), the loading efficiency for Paclitaxel, Rapamycin, and Docetaxel increased by approximately 1.38 times (from 19.7% to 27.1%), 1.35 times (from 20.9% to 28.3%), and 1.54 times (from 19.4% to 29.9%), respectively. Increasing the target loading for all the drugs across all PEG molecular weights resulted in higher loading efficiencies. Interestingly, the average particle size also increased for all drugs and solvent PEGs when the target loading was raised (FIG. 8B). Increasing the final drug concentration in the aqueous solution to 5 mg / mL, did not result in any further change in loading efficiency (FIGs. 8C and 8D).

[0098] Next, the target loading was kept constant at 33.0 wt.% with a PEG4kDa-b- PLA2.2kDa concentration in PEG200-600 of 1.0 wt. / o and increased the target drug concentration in the aqueous medium from 1 mg / mL to 5 mg / mL. This change resulted in no significant difference in either loading efficiency (FIG. 8E) or particle size distribution (FIG. 8F) for any of the drugs or PEG molecular weights. A similar trend was observed when the target loading was fixed at 50.0 wt.% while the target concentration was increased from 1 mg / mL to 5 mg / mL (FIGs. 8C and 8D).

[0099] Notably, regardless of the type of drug, target loading, or target drug concentration in the aqueous medium, micelles derived from crystals obtained from PEG200 supersaturated solutions consistently exhibited the highest loading efficiency, followed by those from PEG600 and PEG400. These observations suggest that the conditions of the supersaturated solution, such as the concentration of different components, including the drug and the molecular weight of the solvent PEG, are more critical in determining the final properties of drug-loaded micelles than the hydration conditions.

[0100] The potential for long-term storage of Rapamycin- and Docetaxel -encapsulating crystals before hydrating them to produce drug-loaded micelles was explored next. Similarto the results for Paclitaxel (FIG. 7C and 7D), crystals were stored at room temperature for 0, 15, or 30 days and then hydrated to a target drug concentration of 1 mg / mL, based on the initial amount of drug in the solution. Storing the Rapamycin (FIGs. 9A and 9B) and Docetaxel (FIGs. 10A and 10B) crystals for 15 or 30 days led to no significant differences (p > 0.05) in encapsulated drug content (FIGs. 9A and 10A) or particle size distribution (FIGs. 9B and 10B) compared to day 0.

[0101] Finally, the capability of the method was examined for co-loading drug combinations at specific ratios consistent with the feed ratio in the supersaturated solution. Paclitaxel and Rapamycin at different ratios (2: 1, 1 : 1, and 1 :2 w / w) were added to the solution while maintaining a copolymer concentration of 1.0 wt.% and a target total drug loading of 33.0 wt.%. As shown in FIG. 11A, the ratio of the loaded drugs into the resulting micelles from crystals was consistent with the feed ratio in the initial supersaturated solution for all molecular weight solvent PEGs, and uniform micelles were produced (FIG. 11B) using the crystallization from supersaturated solution method. The co-loading can also be performed at a higher target drug concentration of 5 mg / mL while still preserving the feed ratio and producing uniform micelles (FIGs. 12A and 12B).

[0102] For some drugs, such as those used here as model drugs (z.e., Paclitaxel, Rapamycin, and Docetaxel), although the drug can be solubilized in aqueous media by polymeric micelles, incompatibility between these hydrophobic drugs and the micelle core may result in instability, with the drug remaining stable in the micelle core for only a few hours. While the crystallization from supersaturated solution method addresses the stability challenge by producing a stable solid form that can be stored for months prior to hydration, the resulting drug-loaded micelles may remain stable for only a few hours following hydration (see FIGs. 13A-13F). To address this, a platform where an oligo(lactic acid) moiety is attached to the parent drug to form an o(LA)n-prodrug, which compatibilizes the drug with the micelle core and improves the aqueous stability of the drugs had previously been introduced. Here, as the next step, the capability of the crystallization from supersaturated solution method for the production of polymeric micelles encapsulating o(LA)s-prodrugs of different drugs, namely Paclitaxel, Rapamycin, and Docetaxel was investigated. These formulations are expected not only to be stable for months in solid form but also to remain stable in aqueous media for days.

[0103] First o(LA)8-Paclitaxel, o(LA)8-Rapamycin, and o(LA)8-Docetaxelare encapsulated in PEG4kDa-b-PLA2.2kDa micelles at a target loading of 33.0 wt.% (1.0 / 0.5 / 98.5 Copolymer / Prodrug / PEG vi’ vi’ vi’) and the impact of increasing the target loading to 50.0 wt.% (1.0 / 1.0 / 98.0 Copolymer / Prodrug / PEG w / w / w) on loading efficiency and particle size distribution when the micelles were prepared at a 1 mg / mL target drug concentration in the aqueous medium was investigated (FIGs. 14A and 14B).

[0104] The first observation shows that using prodrugs instead of the parent drugs for all three model compounds, regardless of the solvent PEG molecular weight, significantly increases the loading efficiency at a given target loading. For example, at a 33.0 wt.% target loading using PEG200, the loading efficiency increased from 19.7% to 38.5% for o(LA)8- Paclitaxel compared to Paclitaxel, from 20.9% to 31.8% for o(LA)8-Rapamycin compared to Rapamycin, and from 19.4% to 32.5% for o(LA)8-Docetaxel compared to Docetaxel. A similar trend was observed across all molecular weight PEG solvents at both 33.0 and 50.0 wt.% target loadings (FIG. 14A vs. FIG. 8A), possibly due to better compatibility of the o(LA)8-prodrugs with the PLA block.

[0105] Consistent with the parent drugs, prodrug-loaded micelles derived from crystals obtained from PEG200 supersaturated solutions consistently exhibited the highest loading efficiency, followed by those from PEG600 and PEG400. Furthermore, increasing the target loading in the initial supersaturated solution across all PEG molecular weights led to a higher loading efficiency in the resulting polymeric micelles. For instance, using PEG200, when the target loading was increased from 33.0 wt.% to 50.0 wt.% (a 1.5-fold increase), the loading efficiency for o(LA)8-Paclitaxel, o(LA)8-Rapamycin, and o(LA)8-Docetaxel increased by approximately 1.16 times (from 38.5% to 44.6%), 1.55 times (from 31.8% to 49.4%), and 1.41 times (from 32.5% to 45.8%), respectively. The increase in loading efficiency was more significant for o(LA)8-Rapamycin and o(LA)8-Docetaxel compared to o(LA)8-Paclitaxel. Further studies are required to investigate the origin of this observation, but one possible explanation could be that o(LA)8-Paclitaxel already exhibits a significantly higher loading efficiency at 33.0 wt.% target loading, nearing its plateau point for loading. This may limit the additional prodrug that can be encapsulated, even with an increased amount of prodrug in the solution — essentially, it reaches its loading saturation point faster.

[0106] Similar to the parent drugs, the average particle size also increased for all prodrugs and solvent PEGs when the target loading was raised (FIG. 14B). It is important to note that the larger average particle size of prodrug-loaded micelles compared to their corresponding drug-loaded ones has been observed in our previous studies using other fabrication methods, and is not specific to the crystallization from supersaturated solution method.

[0107] A similar trend was observed for all the analyses mentioned above when the final prodrug concentration in the aqueous solution was set at 5 mg / mL, and the target loading was increased from 33.0 wt.% to 50.0 wt.%, with no significant difference in loading efficiency and particle size distribution between the 1 mg / mL and 5 mg / mL target drug concentrations (FIGs. 14C-14F) In other words, similar to the parent drugs, the conditions of the supersaturated solution, such as the concentration of different components, including the drug and the molecular weight of the solvent PEG, are more critical in determining the final properties of prodrug-loaded micelles than the hydration conditions.

[0108] Next, the impact of using prodrugs versus parent drugs on the stability of the encapsulated drug in polymeric micelles in aqueous solution at a 33.0 wt.% target loading and 1 mg / mL target drug concentration was investigated. As shown in FIG. 15A, using o(LA)8-Paclitaxel, the entire encapsulated drug remained stable for over 24 hours at room temperature, while for the parent drug, encapsulated Paclitaxel began to decrease after 2 hours, with only a negligible amount remaining after 6 hours. This pattern was consistent across all molecular weights of solvent PEG. Particle size distribution measurements (FIG. 15B) further confirmed these observations, as o(LA)8-Paclitaxel-encapsulating micelles maintained a uniform particle size distribution throughout the 24-hour period, whereas Paclitaxel-encapsulating formulations began to exhibit a non-uniform bimodal particle size distribution after 2 hours at room temperature. Similar to Paclitaxel, Rapamycin and Docetaxel prodrugs demonstrated improved stability in PEG4kDa-b-PLA2.2kDa micelles at room temperature in aqueous solution compared to the parent drugs (FIGs. 16A-16F).

[0109] The potential for long-term storage of o(LA)8-Paclitaxel-, o(LA)8-Rapamycin-, and o(LA)8-Docetaxel-encapsulating crystals before hydrating them to produce prodrug- loaded micelles was then explored. Similar to the parent drugs, crystals were stored at room temperature for 0, 15, or 30 days and then hydrated to a target prodrug concentration of 1 mg / mL, based on the initial amount of prodrug in the solution. Storing the o(LA)8-Paclitaxel(FIGs. 17A and 17B), o(LA)8-Rapamycin (FIGs. 18A and 18B), and o(LA)8-Docetaxel (FIGs. 19A and 19B) crystals for 15 or 30 days led to no significant differences (p > 0.05) in encapsulated drug content (FIGs. 17A, 18A, and 19A) or particle size distribution (FIGs. 17B, 18B, and 19B) compared to day 0.

[0110] Finally, it was investigated whether the prodrug-loaded crystals could be rapidly converted into prodrug-loaded micelles upon hydration, similar to the parent drugs. The dissolution rate of o(LA)8-Paclitaxel-encapsulating crystals was examined by vortexagitating them in water at 5 -second intervals, measuring the o(LA)8-Paclitaxel content in the solution (expressed as a percentage of the initial prodrug), and monitoring the formation of polymeric micelles. As shown in FIG. 20A, the o(LA)8-Paclitaxel content in the solution reached a plateau after 5 seconds of agitation, demonstrating the rapid dissolution rate of these crystals in water. Particle size distribution analysis indicates that 5 seconds of agitation results in the formation of uniform polymeric micelles (FIG. 20B).[OHl] Based on the evidence, the crystallization from supersaturated solution method was concluded to be effective for producing prodrug-containing crystals, which can be stored long-term and subsequently converted into drug-loaded polymeric micelles upon hydration and slight agitation, yielding a stable aqueous formulation.Example 5 - Effect on the cytotoxicity of the final product

[0112] The method described herein allows for the production of drug-loaded polymeric micelles from crystals obtained from supersaturated solutions using PEG as the solvent. The use of different PEG molecular weights or varying target loadings results in differences in the physicochemical properties of the formulations, such as loading efficiency and / or particle size distribution. The effect of altering process parameters, such as the molecular weight of the solvent PEG or target loading, on the cytotoxicity of the formulations was also investigated.

[0113] To explore this, Paclitaxel-loaded PEG4kDa-b-PLA2.2kDa micelles were produced using crystals obtained from PEG200-600 supersaturated solutions (1 wt.% copolymer) at 33.0 or 50.0 wt.% target loading, and their cytotoxicity against 4T1 and MDA-MB-231 breast cancer cell lines was assessed at different Paclitaxel concentrations. According to the results (FIGs. 21A-21D), the molecular weight of the solvent PEG has a significant impacton the cytotoxicity of the formulations against both cell lines, while the impact of target loading is less pronounced. Formulations produced using PEG200 showed the highest cytotoxicity against both cell lines across almost all concentrations tested. Paclitaxel-loaded micelles made with PEG200, regardless of the target loading, were able to kill more than 80% of 4T1 and MDA-MB-231 cells at Paclitaxel concentrations as low as 0.16 and 0.08 mg / mL, respectively. In contrast, when PEG600 was used, a Paclitaxel concentration greater than 1.25 mg / mL was required to achieve comparable cytotoxicity. Overall, the data suggest that the cytotoxicity of the samples prepared using PEG200 is the highest, followed by PEG400, and then PEG600.

[0114] This observed cytotoxicity cannot be solely attributed to the impact of PEG molecular weight on loading efficiency, as PEG600 samples consistently showed higher loading efficiency than PEG400 samples. Although PEG itself can have concentrationdependent cytotoxicity, the observed effects are unlikely to result from the cytotoxic effect of the solvent PEG for several reasons:1. While a substantial amount of PEG is used as the solvent in the described method, the majority is not incorporated into the final formulation, as the crystals are separated from the PEG solution and then hydrated to produce the drug-loaded PEG- b-PLA micelles. This process may leave behind residual amounts of low molecular weight PEG, either mixed with or incorporated into the crystals, but the PEG content in the final formulation is expected to be negligible.2. The IC50 range reported for PEG200 (e.g., 300 mg / mL against Caco-2 cells) is significantly higher than the concentrations of PEG that the cells would be exposed to in this context. Such high PEG concentrations would only be encountered if the cells were exposed to the entire supersaturated solution.3. Comparable cytotoxicity has been reported for low molecular weight PEGs, but the significantly different cytotoxicity pattern observed here suggests that the observed cytotoxicity may not be due to the direct effect of PEG on the cells.

[0115] It is hypothesized that the impact of the solvent PEG molecular weight on the cytotoxicity of the formulations may be an indirect result of its influence on the structure of the crystals and the resulting micelles. For instance, the effect of changing the molecularweight of solvent PEG on the melting onset of the resulting crystals is demonstrated (FIG. IB). Incorporation of short PEG chains into the crystals, and subsequently into the micelle structure, may influence molecular assembly and drug release.Example 6 - Loading PROTAC in polymeric micelles using the “Crystallization from Supersaturated Solution” method

[0116] Gefitinib-based PROTAC 3 is a specialized molecule designed as part of the PROTAC (Proteolysis Targeting Chimeras) strategy, which aims to selectively degrade specific proteins within cells. This compound is a conjugate of gefitinib, an EGFR (epidermal growth factor receptor) inhibitor, linked to a von Hippel-Lindau (VHL) ligand through a chemical linker. The purpose of this design is to induce the targeted degradation of EGFR by the cell's proteasome system, effectively reducing the levels of EGFR in cells that are dependent on it for growth and survival.

[0117] Gefitinib-based PROTAC 3 has shown potent activity in degrading EGFR in specific cancer cell lines, particularly those with mutations in EGFR such as HCC827 (exon 19 deletion) and H3255 (L858R mutation). This degradation activity is significant because EGFR mutations are commonly associated with resistance to conventional EGFR inhibitors in cancers like non-small cell lung cancer (NSCLC). By degrading the mutated EGFR protein rather than just inhibiting its activity, PROTACs like Gefitinib-based PROTAC 3 offer a promising therapeutic approach, especially for overcoming drug resistance. This molecule is hydrophobic and requires solubilization for effective administration. The potential application of the “Crystallization from Supersaturated Solution” method described herein was explored for loading Gefitinib-based PROTAC 3 into polymeric micelles.

[0118] Gefitinib-based PROTAC 3 was successfully loaded into PEG4kDa-b-PLA2.2kDa micelles using PEG200-600 as the solvent at a 33.0 wt.% target drug loading, with target drug concentrations of 1 and 5 mg / mL in aqueous medium. As shown in FIGs. 22A and 22B, PROTAC 3 was loaded into the polymeric micelles with a loading efficiency comparable to other drugs at both concentrations. The particle size distribution revealed a mixture of polymeric micelles, along with some larger particles, particularly when PEG200 was used as the solvent.Example 7 - Fabrication of polymeric micelles using different block copolymers with varying molecular weights

[0119] The potential of the "Crystallization from Supersaturated Solution" method for producing micelles from various block copolymers with different molecular weights was investigated. Specifically, (a) the molecular weight of the PEG block was kept at 4-5 kDa while increasing the molecular weight of the PLA block from 2.2 kDa to 3, 8, or 16 kDa in PEG-b-PLA; (b) the molecular weight of the PLA block was kept at 2.2-2.3 kDa while increasing the molecular weight of the PEG block to 7.5 kDa in PEG-b-PLA; and (c) the method was applied to prepare micelles from PEG-b-PCL (Polycaprolactone) and PEG-b- PS (polystyrene) block copolymers.

[0120] FIGs. 23A-23C demonstrates the results of using the method to prepare micelles from different molecular weights of PEG-A-PLA, as well as PEG-A-PCL and PEG-A-PS copolymers. In most cases, all molecular weight solvent PEGs produced uniform micelles, although in some instances, the samples contained a mixture of micelles and larger particles. Overall, the data suggests that the method described herein is broadly applicable to various copolymers.

[0121] The "crystallization from supersaturated solution" method described herein provides a robust and versatile platform for producing stable, drug-loaded polymeric micelles. This technique effectively encapsulates various parent drugs and their oligo(lactic acid)- prodrugs within polymeric micelles, achieving high loading efficiency while maintaining drug stability over extended storage periods. The method's flexibility in using different molecular weights of PEG as solvents and adjusting formulation parameters, such as target loading, allows for precise control over micelle properties, including particle size and loading efficiency. Furthermore, the rapid dissolution of crystals into uniform micelles upon hydration, along with the elimination of the need for freeze-drying, underscores the method's practicality for large-scale production and long-term storage. These methods hold significant promise for advancing the formulation of hydrophobic drugs in micellar systems, particularly by enhancing their stability and storage in solid form.EQUIVALENTS

[0122] While certain embodiments have been illustrated and described, a person with ordinary skill in the art, after reading the foregoing specification, can effect changes, substitutions of equivalents and other types of alterations to the conjugates and micelles of the present technology or derivatives, prodrugs, or pharmaceutical compositions thereof as set forth herein. Each aspect and embodiment described above can also have included or incorporated therewith such variations or aspects as disclosed in regard to any or all of the other aspects and embodiments.

[0123] The present technology is also not to be limited in terms of the particular aspects described herein, which are intended as single illustrations of individual aspects of the present technology. Many modifications and variations of this present technology can be made without departing from its spirit and scope, as will be apparent to those skilled in the art. Functionally equivalent methods within the scope of the present technology, in addition to those enumerated herein, will be apparent to those skilled in the art from the foregoing descriptions. Such modifications and variations are intended to fall within the scope of the appended claims. It is to be understood that this present technology is not limited to particular methods, conjugates, reagents, compounds, compositions, labeled compounds or biological systems, which can, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular aspects only, and is not intended to be limiting. Thus, it is intended that the specification be considered as exemplary only with the breadth, scope and spirit of the present technology indicated only by the appended claims, definitions therein and any equivalents thereof.

[0124] The embodiments, illustratively described herein may suitably be practiced in the absence of any element or elements, limitation or limitations, not specifically disclosed herein. Thus, for example, the terms “comprising,” “including,” “containing,” etc. shall be read expansively and without limitation. Additionally, the terms and expressions employed herein have been used as terms of description and not of limitation, and there is no intention in the use of such terms and expressions of excluding any equivalents of the features shown and described or portions thereof, but it is recognized that various modifications are possible within the scope of the claimed technology. Additionally, the phrase “consisting essentially of’ will be understood to include those elements specifically recited and thoseadditional elements that do not materially affect the basic and novel characteristics of the claimed technology. The phrase “consisting of’ excludes any element not specified.

[0125] In addition, where features or aspects of the disclosure are described in terms of Markush groups, those skilled in the art will recognize that the disclosure is also thereby described in terms of any individual member or subgroup of members of the Markush group. Each of the narrower species and subgeneric groupings falling within the generic disclosure also form part of the invention. This includes the generic description of the invention with a proviso or negative limitation removing any subject matter from the genus, regardless of whether or not the excised material is specifically recited herein.

[0126] As will be understood by one skilled in the art, for any and all purposes, particularly in terms of providing a written description, all ranges disclosed herein also encompass any and all possible subranges and combinations of subranges thereof. Any listed range can be easily recognized as sufficiently describing and enabling the same range being broken down into at least equal halves, thirds, quarters, fifths, tenths, etc. As a nonlimiting example, each range discussed herein can be readily broken down into a lower third, middle third and upper third, etc. As will also be understood by one skilled in the art all language such as “up to,” “at least,” “greater than,” “less than,” and the like, include the number recited and refer to ranges which can be subsequently broken down into subranges as discussed above. Finally, as will be understood by one skilled in the art, a range includes each individual member.

[0127] All publications, patent applications, issued patents, and other documents (for example, journals, articles and / or textbooks) referred to in this specification are herein incorporated by reference as if each individual publication, patent application, issued patent, or other document was specifically and individually indicated to be incorporated by reference in its entirety. Definitions that are contained in text incorporated by reference are excluded to the extent that they contradict definitions in this disclosure.

[0128] The present technology may include, but is not limited to, the features and combinations of features recited in the following lettered paragraphs, it being understood that the following paragraphs should not be interpreted as limiting the scope of the claims as appended hereto or mandating that all such features must necessarily be included in such claims:A. A composition comprising a crystalline PEG copolymer, a hydrophobic drug, and optionally a PEG homopolymer, wherein the composition is solid; the crystalline PEG copolymer has at least one crystalline PEG block and at least one polymer block other than PEG; the PEG homopolymer has a molecular weight from about 200 Da to about 800 Da; and the hydrophobic drug has a water solubility of <10 mg / mL at 25 °C.B. The composition of Paragraph A, wherein the PEG copolymer is a di-block or tri-block copolymer.C. The composition of Paragraph A or Paragraph B, wherein the at least one polymer block other than PEG is crystalline.D. The composition of Paragraph A or Paragraph B, wherein the at least one polymer block other than PEG is non-crystalline.E. The composition of any one of Paragraphs A-D, wherein the at least one polymer block other than PEG is poly(D,L-lactic acid) (PLA), poly(s-caprolactam) (PCL), poly(lactic-co-glycolic acid), polypropylene oxide (PPO), poly(methyl methacrylate) (PMMA), poly(N-isopropylacrylamide) (PNIPAM), polystyrene, poly(L-lactic acid), poly(D-lactic acid).F. The composition of any one of Paragraphs A-E, wherein the molecular weight of the crystalline PEG copolymer is about 1.5 kDa to about 50 kDa.G. The composition of Paragraph F, wherein the molecular weight of the crystalline PEG copolymer is about 3 kDa to about 10 kDa.H. The composition of any one of Paragraphs A-G, wherein the ratio of the molecular weight of the crystalline PEG bloc(s) to the molecular weight of the non-crystalline bloc(s) is from 15: 1 to 1 : 15.I. The composition of Paragraph H, wherein the ratio of the molecular weight of the crystalline PEG bloc(s) to the molecular weight of the non-crystalline bloc(s) is from 4: 1 to 1 :4.J. The composition of Paragraph H or Paragraph I, wherein the ratio of the molecular weight of the crystalline PEG bloc(s) to the molecular weight of the non-crystalline bloc(s) is from 5 :2 to 1 : 1.K. The composition of any one of Paragraphs A- J, wherein the PEG copolymer is PEG-b-PLAL. The composition of Paragraph K, wherein the PEG block has a molecular weight of about 1.5 kDa to about 35 kDa and the PL A block has a molecular weight of about 1 to about 35 kDa.M. The composition of Paragraph K, wherein the PEG block has a molecular weight of about 1.5 to about 10 kDa and the PLA block has a molecular weight of about 1.5 to about 16 kDa.N. The composition of Paragraph K, wherein the PEG block has a molecular weight of about 4 kDa and the PLA block has a molecular weight of about 2.2 kDa.O. The composition of any one of Paragraphs A-N, wherein the PEG homopolymer has a molecular weight of about 200 to about 600 Da.P. The composition of any one of Paragraphs A-O, wherein the composition comprises about 1 wt% to about 50 wt% hydrophobic drug by total weight of the solid composition.Q. The composition of any one of Paragraphs A-P, wherein the composition comprises about 2 wt% to about 15 wt% hydrophobic drug by total weight of the solid composition.R. The composition of any one of Paragraphs A-Q, wherein the hydrophobic drug is selected from the group consisting of paclitaxel, docetaxel, rapamycin, everolimus, selumetinib, binimetinib, gefitinib-based PROTAC 3, GDC-0623, ARRY-300, cabazitaxel, rapamycin, ICU 189150, doxorubicin, etoposide, 17-AAG, bicalutamide, embelin, suberoylanilide hydroxamic acid, P-lapachone, pifithrin-p, sagopilone, thiocoraline, ABT-263, podophyllotoxin, simvastatin, efavirenz, a platinprodrug, VE-822, AZD5363, teniposide, AZD8055, rutin, derivatives and / or conjugates of any of the foregoing, and combinations of two or more thereof.S. A method of preparing a solid composition of any one of Paragraphs A-R comprising crystalizing the composition from a liquid solution of PEG homopolymer, PEG copolymer and hydrophobic drug.T. The method of Paragraph S, wherein the temperature of the liquid solution is from 0°C to about 50°C.U. The method of Paragraph S or Paragraph T, further comprising crystallizing the composition isothermally.V. The method of any one of Paragraphs S-U, wherein the liquid solution comprises about0.5 wt% to about 20 wt% PEG copolymer.W. The method any one of Paragraphs S-V, wherein the weight ratio of PEG copolymer to drug is from 1 : 1 to 40: 1.X. The method of Paragraph W, wherein the weight ratio of PEG copolymer to drug is from 1 : 1 to 3 : 1.Y. The method of any one of Paragraphs S-X, wherein the crystallization is carried out in a glass or plastic vessel.Z. The method of Paragraph Y, wherein the crystallization is carried out in a polypropylene or polyethylene vessel.AA. A method of preparing micelles comprising a hydrophobic drug, wherein the method comprises dissolving the composition of any one of Paragraphs A-R in an amount of water effective to provide the micellesAB. The method of Paragraph AA, wherein the micelles comprise about 1 wt% to about 25 wt% loaded drug.AC. The method of Paragraph AA or Paragraph AB, wherein the micelles have a hydrodynamic diameter of about 10 nm to about 300 nm.AD. The method of Paragraph AC, wherein the micelles have a hydrodynamic diameter of about 10 nm to about 100 nm.

[0129] Other embodiments are set forth in the following claims, along with the full scope of equivalents to which such claims are entitled.

Claims

WHAT IS CLAIMED IS:

1. A composition comprising a crystalline PEG copolymer, a hydrophobic drug, and optionally a PEG homopolymer, wherein the composition is solid; the crystalline PEG copolymer has at least one crystalline PEG block and at least one polymer block other than PEG; the PEG homopolymer has a molecular weight from about 200 Da to about 800 Da; and the hydrophobic drug has a water solubility of <10 mg / mL at 25 °C.

2. The composition of claim 1, wherein the PEG copolymer is a di -block or tri -block copolymer.

3. The composition of claim 1, wherein the at least one polymer block other than PEG is crystalline.

4. The composition of claim 1, wherein the at least one polymer block other than PEG is non-crystalline.

5. The composition of claim 1, wherein the at least one polymer block other than PEG is poly(D,L-lactic acid) (PLA), poly(s-caprolactam) (PCL), poly(lactic-co-glycolic acid), polypropylene oxide (PPO), poly(methyl methacrylate) (PMMA), poly(N- isopropyl acrylamide) (PNIPAM), polystyrene, poly(L-lactic acid), poly(D-lactic acid).

6. The composition of claim 1, wherein the molecular weight of the crystalline PEG copolymer is about 1.5 kDa to about 50 kDa.

7. The composition of claim 6, wherein the molecular weight of the crystalline PEG copolymer is about 3 kDa to about 10 kDa.

8. The composition of claim 1, wherein a ratio of the molecular weight of the crystalline PEG bloc(s) to the molecular weight of the non-crystalline bloc(s) is from 15:1 to 1:15.

9. The composition of claim 8, wherein the ratio of the molecular weight of the crystalline PEG bloc(s) to the molecular weight of the non-crystalline bloc(s) is from 4: 1 to 1 :4.

10. The composition of claim 8, wherein the ratio of the molecular weight of the crystalline PEG bloc(s) to the molecular weight of the non-crystalline bloc(s) is from 5:2 to 1 : 1.

11. The composition of claim 1, wherein the PEG copolymer is PEG-b-PLA.

12. The composition of claim 11, wherein the PEG block has a molecular weight of about 1.5 kDa to about 35 kDa and the PL A block has a molecular weight of about 1 to about 35 kDa.

13. The composition of claim 11, wherein the PEG block has a molecular weight of about 1.5 to about 10 kDa and the PLA block has a molecular weight of about 1.5 to about 16 kDa.

14. The composition of claim 11, wherein the PEG block has a molecular weight of about 4 kDa and the PLA block has a molecular weight of about 2.2 kDa.

15. The composition of claim 1, wherein the PEG homopolymer has a molecular weight of about 200 to about 600 Da.

16. The composition of claim 1, wherein the composition comprises about 1 wt% to about 50 wt% hydrophobic drug by total weight of the solid composition.

17. The composition of claim 1, wherein the composition comprises about 2 wt% to about 15 wt% hydrophobic drug by total weight of the solid composition.

18. The composition of claim 1, wherein the hydrophobic drug is selected from the group consisting of paclitaxel, docetaxel, rapamycin, everolimus, selumetinib, binimetinib, gefitinib-based PROTAC 3, GDC -0623, ARRY-300, cabazitaxel, rapamycin, ICU 189150, doxorubicin, etoposide, 17-AAG, bicalutamide, embelin, suberoylanilide hydroxamic acid, P-lapachone, pifithrin-p, sagopilone, thiocoraline, ABT-263, podophyllotoxin, simvastatin, efavirenz, a platin prodrug, VE-822,AZD5363, teniposide, AZD8055, rutin, derivatives and / or conjugates of any of the foregoing, and combinations of two or more thereof.

19. A method of preparing a solid composition of any one of claims 1-18, the method comprising crystalizing the composition from a liquid solution of PEG homopolymer, PEG copolymer and hydrophobic drug.

20. The method of claim 19, wherein the temperature of the liquid solution is from 0°C to about 50°C.

21. The method of claim 19, further comprising crystallizing the composition isothermally.

22. The method of claim 19, wherein the liquid solution comprises about 0.5 wt% to about 20 wt% PEG copolymer.

23. The method of claim 19, wherein the weight ratio of PEG copolymer to drug is from 1:1 to 40:1.

24. The method of claim 23, wherein the weight ratio of PEG copolymer to drug is from 1:1 to 3:l.

25. The method of claim 19, wherein the crystallization is carried out in a glass or plastic vessel.

26. The method of claim 25, wherein the crystallization is carried out in a polypropylene or polyethylene vessel.

27. A method of preparing micelles comprising a hydrophobic drug, wherein the method comprises dissolving the composition of any one of claims 1-19 in an amount of water effective to provide the micelles.

28. The method of claim 27, wherein the micelles comprise about 1 wt% to about 25 wt% loaded drug.

29. The method of claim 27, wherein the micelles have a hydrodynamic diameter of about 10 nm to about 300 nm.

30. The method of claim 29, wherein the micelles have a hydrodynamic diameter of about 10 nm to about 100 nm.

Images