The present invention relates to an object comprising a composition comprising a biodegradable polymer and mitomycin C and a process for the production thereof. The invention further relates to such object for use as a drug delivery system and for preventing or treating glaucoma.

Glaucoma is the leading cause of irreversible blindness worldwide. By 2020, the prevalence of glaucoma is estimated to be around 80 million people worldwide. High intraocular pressure (IOP) is one of the most important risk factors of glaucoma. All current glaucoma treatment modalities aim at lowering IOP. Initially, this is done with eye drops and/or laser treatment. If these treatments do not have the desired effect, a surgical intervention can be performed, the so-called glaucoma filtration surgery (GFS). GFS is the last resort treatment option for glaucoma patients. Current standard GFS techniques (e.g. trabeculectomy or long-tube glaucoma implant/shunt) have been performed for several decades and are the most effective treatments to achieve sustained IOP reduction. During GFS, an artificial passage (e.g. by placing a shunt) is created for drainage of aqueous humor (AqH) from the anterior chamber into the space under the conjunctiva and Tenon’s capsule, forming a filtering bleb. This procedure will increase outflow of AqH and reduce IOP. GFS requires a substantial follow-up care and does not always lead to a permanent IOP reduction. An important complication is the development of fibrosis (scarring) of the filtering bleb, which often reduces the outflow of AqH through the operatively created drainage passage; as a consequence, IOP will rise again. This phenomenon of IOP rise after GFS is classified as a GFS- failure. This will lead to increased risk of further damage to the optic nerve. Patients may have to undergo new interventions such as a revision or a new surgery procedure and need to restart their eye drop medication.

The introduction of mitomycin C (MMC) administration to augment the outcome of trabeculectomy in the early 1990s resulted in improved long-term IOP control, presumably by its anti-fibrotic action. MMC is an alkylating agent that cross-links the DNA. In GFS, it inhibits fibroblast proliferation and endothelial cell growth. This will reduce or prevent scar formation and increase bleb survival. Application of MMC in ophthalmology, especially in glaucoma procedures, has been increasing in recent years. Currently, intraoperative MMC administration in the sub-Tenon’s space with a sponge soaked in a MMC- solution of 0.2mg/mL or 0.4mg/mL is the gold standard anti- fibrotic treatment in GFS. Unfortunately, MMC administration does not completely prevent failures of current GFS procedures. Even with intraoperative MMC application, there still is a 10% yearly GFS failure rate.

It is an objective of the present invention to provide an object that can be used as a drug delivery device (or drug delivery system) for preventing or treating glaucoma.

Accordingly, the present invention provides an object comprising a polymer composition comprising a biodegradable polymer and MMC, wherein a) the object is a mesh of fibers comprising the polymer composition or b) the object is a multilayer film comprising a first outer layer, a second outer layer and an inner layer provided between and adhered to the first outer layer and the second outer layer, wherein the inner layer comprises the polymer composition and each of the first outer layer and a second outer layer comprises a biodegradable polymer.

It was surprisingly found that the object according to the invention allows the release of MMC over a long period of time. This allows it to be used as a drug delivery device (or drug delivery system) for sustained release of MMC. In embodiments, the drug delivery device (or drug delivery system) can be implanted at an implant site in a human or animal patient. The implant site can be a natural body cavity or space or part of an organ, or a cavity or space defined and/or accessed by a surgical procedure, such as sub-conjunctival or sub-Tenon’s space of the eye. The drug delivery device (or drug delivery system) can provide for prolonged presence of MMC at the implant site, preferably during the period of wound healing. The wound healing period is a critical period for the development of a properly functioning filtration bleb. Accordingly, the object according to the invention preferably releases MMC over a period of at least 20 days, more preferably at least 25 days, more preferably at least 28 days, more preferably at least 30 days. After 28 days, the wound healing is normally completed.

The object according to the invention is soft, easy to handle and easy to implant e.g. using a forceps. Further, the biodegradable polymer can alleviate or prevent the problem of a foreign body reaction from the drug delivery device (or drug delivery system).

Preferably, the object has a size of 1.0 to 5.0 mm. Such size allows easy implanting. Herein, size of the object is understood as the largest dimension of the object. For example, when the object has a generally cylindrical shape, the diameter of the cross section of the cylinder or the height of the cylinder, whichever is larger, is in the range of 1.0 to 5.0 mm.

The present invention further provides the object according to the invention for use as an implantable drug delivery device (or drug delivery system) for sustained release of MMC. The drug delivery device (or drug delivery system) can be implanted at an implant site in a human or animal patient. The implant site can be a natural body cavity or space or part of an organ, or a cavity or space defined and/or accessed by a surgical procedure, such as sub-conjunctival or sub-Tenon’s space of the eye.

The present invention further provides the object according to the invention for preventing or treating glaucoma. The present invention further provides use of the object according to the invention for preventing or treating glaucoma.

The present invention further provides the object according to the invention for reducing intraocular pressure in an eye of a human or animal patient. The present invention further provides use of the object according to the invention for reducing intraocular pressure in an eye of a human or animal patient.

In embodiments, the object according to the invention can be a physical material body that can be seen and touched.

In embodiments, the object according to the invention can be formed from a polymer composition and MMC, wherein the polymer composition dissolves or biodegrades in the presence of an aqueous fluid, such as aqueous humor. As used herein, “aqueous fluid” is a fluid that includes, relates to, or resembles water. As used herein, “aqueous fluid” is a transparent water-like fluid that is a component of both the anterior and the posterior chambers of the eye; it is secreted from the ciliary body, which is a structure that also supports the crystalline lens of the eye.

In embodiments, the object according to the invention can be an implantable drug delivery device (or drug delivery system) or a plurality of drug delivery devices (or drug delivery systems) that holds a supply of one or more therapeutic agents and delivers the therapeutic agent(s) from the device or system over time. In embodiments, the one or more therapeutic agents can include MMC. The present invention further provides a method for preventing or treating glaucoma, comprising placing the object according to the invention into the sub-Tenon’s space of a human or animal patient.

The present invention further provides a process for making the object according to the invention, comprising the steps of: i) preparing a polymer solution of the biodegradable polymer in an organic solvent, wherein the polymer solution comprises the mitomycin C and ii) converting the polymer solution into the object according to the invention.

Biodegradable polymer

The biodegradable polymer in the polymer composition can be any non-toxic biodegradable polymer, preferably selected from the group consisting of polylactide, polyglycolide, poly(lactic-co-glycolic acid) (PLGA), polycaprolactone (PCL) and combinations thereof, more preferably selected from the group consisting of poly(lactic- co-glycolic acid), polycaprolactone and their combination.

When the object of the invention is a multilayer film, the biodegradable polymer in each of the first outer layer and a second outer layer is preferably selected from the group consisting of polylactide, polyglycolide, poly(lactic-co-glycolic acid) (PLGA), polycaprolactone (PCL) and combinations thereof, more preferably selected from the group consisting of poly(lactic-co-glycolic acid), polycaprolactone and their combination. Preferably, the biodegradable polymer in each of the first outer layer and a second outer layer is of the same type as the biodegradable polymer in the polymer composition.

In some preferred embodiments, the biodegradable polymer is polycaprolactone. This is advantageous in terms of the increased softness of the object according to the invention.

Most preferably, the biodegradable polymer is poly(lactic-co-glycolic acid). This is advantageous in that the object of the invention degrades very fast. The weight ratio between the lactic acid monomer unit and the glycolic acid monomer unit in the poly(lactic-co-glycolic acid) may e.g. be 1 :5 to 5: 1 , for example 1:1 to 5: 1.

The poly(lactic-co-glycolic acid) may be an ester terminated poly(lactic-co-glycolic acid), an acid terminated poly(lactic-co-glycolic acid) or a combination thereof. In some preferred embodiments, the poly(lactic-co-glycolic acid) is a combination of an ester terminated poly(lactic-co-glycolic acid) and an acid terminated poly(lactic-co-glycolic acid). This allows optimizing the processibility during the step of converting the polymer solution into the object according to the invention, in particular the mesh of fibers. The weight ratio between the ester terminated poly(lactic-co-glycolic acid) and the acid terminated poly(lactic-co-glycolic acid) may e.g. be 1:5 to 5:1, for example 1 :1 to 5:1.

In embodiments, the biodegradable polymer dissolves or biodegrades in the presence of an aqueous fluid, such as aqueous humor.

Mitomycin C

Mitomycin C may be mixed with other components in the composition (e.g. biodegradable polymer, organic solvent) as a technical grade mitomycin C (pure MMC) or a clinical grade mitomycin C (MMC and additives). The polymer composition in the object according to the invention may therefore comprise additives in addition to the biodegradable polymer and mitomycin C.

It was found that the use of a technical grade MMC results in a prolonged release of MMC. Although not wishing to be bound by any theory, the presence of (water-soluble) additives in the clinical grade MMC may lead to an accelerated release of MMC. Accordingly, preferably, step a) of the process for making the object according to the invention involves mixing mitomycin C in the form of mitomycin C free of additives with the organic solvent.

Preferably, the amount of mitomycin C in the polymer composition with respect to the total of the biodegradable polymer and mitomycin C in the polymer composition is 0.1 to 5.0 wt%, more preferably 0.3 to 3.5 wt%, for example 0.3 to 1.5 wt% or 1.5 to 3.5 wt%. The higher amount of the mitomycin C may lead to a stronger and faster elution of the mitomycin C from the object according to the invention.

Process

In step a) of the process for making the object according to the invention, a polymer solution of the biodegradable polymer in an organic solvent is prepared, wherein the polymer solution comprises mitomycin C. In step b) this polymer solution is subsequently converted into the object according to the invention. The process according to the invention may further comprise the step of adjusting the shape and/or the size of the object during and/or after step b). This may be performed by any known means such as by molding, punching or cutting.

The polymer solution to be subjected to step b) may comprise mitomycin C in a dissolved state or as solid particles.

Dispersion of MMC

In some embodiments, solid particles of mitomycin C are dispersed in the polymer solution. In these cases, the polymer solution is thus a dispersion of solid particles of mitomycin C in a dispersion medium which is a solution of the biodegradable polymer in the organic solvent. It was found that this advantageously results in a highly prolonged mitomycin C release and a highly increased mitomycin C stability.

This dispersion medium may be achieved by preparing a solution of the biodegradable polymer in the organic solvent and dispersing mitomycin C therein.

In these cases, the organic solvent is selected so that the biodegradable polymer dissolves in it and mitomycin C does not (completely) dissolve in it. The biodegradable polymer is rather non-polar and mitomycin C is rather polar. Accordingly, the organic solvent used for the present embodiments is preferably non-polar.

The organic solvent used for the present embodiments may be a mixture of organic solvents having different polarities. For example, the organic solvent may be a mixture of a solvent with a moderate polarity for dissolving the biodegradable polymer and a highly non-polar solvent for preventing the (complete) dissolution of the mitomycin C. The types of the moderately polar solvent and the highly non-polar solvent and their ratio can be suitably selected by the skilled person in order to prepare a dispersion in which the biodegradable polymer is sufficiently dissolved while mitomycin C sufficiently remains as solid particles.

Preferably, the organic solvent is further selected to have a suitable volatility for the step of converting the polymer solution into the object of the invention.

Particularly in the cases where the polymer solution is to be converted into a mesh of fibers, the organic solvent is preferably sufficiently volatile such that it evaporates and fibers are formed. A part of the organic solvent preferably does not evaporate during the process, and acts as a plasticizer in the mesh of fibers as well as a tackifier to allow new fibers to stick to underlying fibers. A mixture of organic solvent may be used to achieve the volatility suitable for conversion into a mesh of fibers.

Suitable examples of the organic solvent are described herein for the purpose of illustration. Based on this description, the person skilled in the art can select the suitable types and amounts of the organic solvent to achieve a dispersion of solid particles of mitomycin C in a dispersion medium which is a solution of the biodegradable polymer in the organic solvent.

Preferably, the organic solvent comprises at least one of dichloromethane and chloroform, preferably at an amount of 70 to 90 vol% with respect to the total amount of the organic solvent. They have suitable levels of polarity for dissolving the biodegradable polymer while allowing the mitomycin C to be maintained as solid particles optionally with the help of a further solvent which has a lower polarity. More preferably, the organic solvent comprises dichloromethane. Dichloromethane has a suitable level of volatility for conversion of the polymer solution into a mesh of fibers.

Preferably, the organic solvent comprises at least one of a C4-C8 alkane and a petroleum ether, preferably at an amount of 10 to 30 vol% with respect to the total amount of the organic solvent. They have sufficiently high levels of non-polarity for maintaining the mitomycin C as solid particles. Preferably, the C4-C8 alkane is a C5 or C6 alkane, preferably selected from n-pentane, iso-pentane, and n-hexane, most preferably n-pentane. Wherein n-pentane has a suitable level of volatility for conversion of the polymer solution into a mesh of fibers.

The organic solvent may comprise other non-polar solvents such as toluene, amylene, benzene and/or cyclohexane. However, the organic solvent may be substantially free of toluene, amylene, benzene and c-hexane in view of e.g. toxicity or high viscosity.

The organic solvent may comprise a plasticizer. This is particularly advantageous when the biodegradable polymer is PLGA and the polymer solution is to be converted into a mesh of fibers. The plasticizer is preferably selected from the group consisting of ethyl lactate, ethyl acetate, phenyl acetate, N,N-dimethyl formamide, toluene and dimethylsulfoxide. The amount of the plasticizer may e.g. be 100 pL to 500 pL per 1000 mg of the biodegradable polymer. Such amount will ensure that the polymer solution is converted into mesh of fibers instead of a homogeneous film. Particularly preferably, the plasticizer comprises or is ethyl lactate. It has a low volatility and stays in the mesh during its production and makes the fibers flexible and not rip or break into short fibers which would result in an unstable meshwork. Ethyl lactate is generally recognized as safe (GRAS) and thus is not expected to be a problem even if traces remain after drying. Further, it does not interfere with the degradation mechanism of the biodegradable polymer.

In some particularly preferred embodiments, the organic solvent comprises at least one of dichloromethane and chloroform and at least one of a C4-C8 alkane and a petroleum ether. Particularly preferably, the organic solvent comprises dichloromethane and n-pentane.

In some particularly preferred embodiments, the organic solvent comprises at least one of dichloromethane and chloroform and at least one of a C4-C8 alkane and a petroleum ether and further a plasticizer. Particularly preferably, the organic solvent comprises dichloromethane, n-pentane, and ethyl lactate.

The amount of the organic solvent may be selected based on the type and the molecular weight of the biodegradable polymer. The amount of the organic solvent may e.g. be 3.0 to 100 mL per 1000 mg of the biodegradable polymer. When the biodegradable polymer is PCL, the amount of the organic solvent may preferably be 1.0 to 10 vol/wt%, for example 2.1 to 8.0 vol/wt% with respect to the biodegradable polymer. When the biodegradable polymer is PLGA, the amount of the organic solvent may preferably be 3.0 to 50 mL, for example 5.0 to 30 mL, per 1000 mg of the biodegradable polymer.

Solution of mitomycin C

In some embodiments, the polymer solution is a solution of mitomycin C and the biodegradable polymer in the organic solvent.

In order to dissolve both mitomycin C and the biodegradable polymer, the organic solvent is preferably polar. For example, the organic solvent may comprise or be dichloromethane, acetone, chloroform, or N,N-dimethylacetamide. The organic solvent preferably does not comprise a highly non-polar solvent such as n-pentane. The solution may be obtained by dissolving mitomycin C in the organic solvent and dissolving the biodegradable polymer therein to obtain a solution of mitomycin C and the biodegradable polymer in the organic solvent. For example, mitomycin C may be dissolved in acetone and PLGA may be dissolved therein.

The solution may be obtained by dissolving the biodegradable polymer in the organic solvent and dissolving mitomycin C therein to obtain a solution of the mitomycin C and the biodegradable polymer in the organic solvent.

The solution may be obtained by dissolving the biodegradable polymer in a first organic solvent to obtain a first solution and dissolving mitomycin C in a second organic solvent to obtain a second solution and mixing the first solution and the second solution to obtain a solution of mitomycin C and the biodegradable polymer in the organic solvent which is a mixture of the first organic solvent and the second organic solvent. For example, PCL may be dissolved in chloroform and mitomycin C may be dissolved in N,N-dimethylacetamide and the two solutions may be mixed to obtain a solution of PCL and mitomycin C in a mixture of chloroform and N,N-dimethylacetamide. PCL may be dissolved in dichloromethane and mitomycin C may be dissolved in N,N- dimethylacetamide and the two solutions may be mixed to obtain a solution of PCL and mitomycin C in a mixture of dichloromethane and N,N-dimethylacetamide.

Mesh of fibers

In some embodiments, the object according to the invention is a mesh of fibers comprising the polymer composition. The fibers forming the mesh are made of the polymer composition comprising the biodegradable polymer and mitomycin C. The mitomycin C can be dispersed within the biodegradable polymer of the fibers. The fibers are loosely entangled or an interpenetrating polymer network to form a mesh.

The object according to the invention in the form of a mesh of fibers is highly advantageous in that it is very soft, preventing erosion of the ocular tissues. Further, it allows the release of mitomycin C over a very long period of time.

In the process for making the object in the form of a mesh of fibers, step b) may involve spraying or electrospinning the polymer solution to obtain the mesh of fibers. Spraying and electrospinning of a liquid for making a mesh of solid fibers is per se well- known and is described e.g. in Electrospinning for Drug Delivery Systems: Drug Incorporation Techniques, Manuel et.al. , https://www.intechopen.com/chapters/52962.

The invention provides the object of the invention which is a mesh of fibers comprising a polymer composition comprising a biodegradable polymer and a mitomycin C, wherein the object is obtained by a process comprising i) preparing a polymer solution of the biodegradable polymer in an organic solvent, wherein solid particles of mitomycin C are dispersed in the polymer solution and ii) converting the polymer solution into the object according to the invention, preferably wherein the biodegradable polymer is PLGA.

Multilayer structure

In some embodiments, the object according to the invention is a multilayer film comprising a first outer layer, a second outer layer and an inner layer provided between and adhered to the first outer layer and the second outer layer. The inner layer comprises the composition comprising the biodegradable polymer and mitomycin C. Each of the first outer layer and the second outer layer comprises a biodegradable polymer. The biodegradable polymer in the inner layer, the first outer layer and the second outer layer may be of the same type or of different types.

The multilayer film may consist of the first outer layer, the second outer layer and the inner layer.

The multilayer film may comprise one or more further layers. On the side of the first outer layer opposite from the side facing the inner layer, one or more further layers may be provided. Similarly, on the side of the second outer layer opposite from the side facing the inner layer, one or more further layers may be provided.

Each of the inner layer, the first outer layer and the second outer layer may be formed from a polymer solution of the biodegradable polymer with mitomycin C dissolved or dispersed in the polymer solution by any known film-making method, e.g., by solvent casting. The mitomycin C can be dispersed within the biodegradable polymer of each layer.

The obtained layers may be stacked and adhered to each other e.g. by compression molding. Thus, in the process for making the object, step b) may involve providing the first outer layer, the second outer layer and the inner layer and consolidating the first outer layer, the second outer layer and the inner layer to obtain the multilayer film.

It is noted that the invention relates to the subject-matter defined in the independent claims alone or in combination with any possible combinations of features described herein, preferred in particular are those combinations of features that are present in the claims. It will therefore be appreciated that all combinations of features relating to the composition according to the invention; all combinations of features relating to the process according to the invention and all combinations of features relating to the composition according to the invention and features relating to the process according to the invention are described herein.

It is further noted that the term ‘comprising’ does not exclude the presence of other elements. However, it is also to be understood that a description on a product/composition comprising certain components also discloses a product/composition consisting of these components. The product/composition consisting of these components may be advantageous in that it offers a simpler, more economical process for the preparation of the product/composition. Similarly, it is also to be understood that a description on a process comprising certain steps also discloses a process consisting of these steps. The process consisting of these steps may be advantageous in that it offers a simpler, more economical process.

When values are mentioned for a lower limit and an upper limit for a parameter, ranges made by the combinations of the values of the lower limit and the values of the upper limit are also understood to be disclosed.

The invention is now elucidated by way of the following examples and the figures, without however being limited thereto.

Figure 1 : Overview of all different drug delivery systems (DDSs) made from PolyCaproLactone (PCL) or Poly Lactic-co-Glycolic Acid (PLGA). Films (prototype 6 until prototype 9), Hamburgers (prototype 1 and prototype 2), and Meshworks (prototype 3, prototype 5, prototype 11 until prototype 15, and prototype 17 until prototype 20) contained either technical or clinical grade mitomycin C in solution (dissolved mitomycin C) or as solid particles (crystalized mitomycin C). Figure 2: Release kinetics (mean values; n=3) of technical grade mitomycin C (in g) in 3 different drug delivery systems (DDSs) in time; PCL-f_1% (dissolved) [prototype 6], PCL-H_0.3% (dissolved) [prototype 1], and PCL-M_2.1% (dissolved) [prototype 3],

Figure 3: Legend: Images of DDSs made of PLGA. A shows a three-layered Hamburger, B shows a Meshwork design. C is a Scanning EM image of the whole PLGA Meshwork DDS and D is a close-up of the structure in C.

Figure 4: The effect of using dissolved mitomycin C or solid particles of mitomycin C for the production of the DDS. Release (in %, corrected for the load of mitomycin C at t=0) of the release kinetics (n=3) of technical grade mitomycin C (in pg) in 2 different drug delivery systems (DDSs) in time; PCL-f_1% (dissolved) [prototype 6] and, PCL-f_1% (crystallized) [prototype 8],

Figure 5(a): Absorption spectra of the aqueous elusion from PLGA-M DDSs normalized at absorption maximum of mitomycin C at 365 nm using dissolved MMC.

Figure 5(b): Absorption spectra of the aqueous elusion from PLGA-M DDSs normalized at absorption maximum of mitomycin C at 365 nm using solid particles of MMC

Figure 6: Mean (A) and total release (in %, corrected for the load of MMC at t=0) (B) of the release kinetics (n=3) of technical grade MMC (in pg) in 3 different drug delivery systems (DDSs) in time; PCL-M_3% (crystalized) [prototype 13], PCL-M_2% (crystalized) [prototype 12], and PCL-M_1% (crystalized) [prototype 11],

Figure 7: Mean (A) and total release (in %, corrected for the load of MMC at t=0) (B) of the release kinetics (n=3) of technical grade MMC (in pg) in 3 different drug delivery systems (DDSs) in time; PLGA-M_3% (crystalized) [prototype 5], PLGA-M_2% (crystalized) [prototype 15], and PLGA-M_1% (crystalized) [prototype 14],

Figure 8: Mean (A) and total release (in %, corrected for the load of MMC at t=0) (B) of the release kinetics (n=3) of clinical grade MMC (in pg) in 3 different drug delivery systems (DDSs) in time; PLGA-M_3% (crystalized) [prototype 18], PLGA-M_1% (crystalized) [prototype 19], and PLGA- M_0.5% (crystalized) [prototype 20], Figure 9: Mean (A) and total release (in %, corrected for the load of MMC at t=0) (B) of the release kinetics (n=3) of technical or clinical grade MMC (in g) in 2 different, PCL- based, drug delivery systems (DDSs) in time; PCL-M_3% (crystalized) with technical grade MMC [prototype 13] and PCL-M_3% (crystalized) with clinical grade MMC [prototype 17],

Figure 10: Mean (A) and total release (in %, corrected for the load of MMC at t=0) (B) of the release kinetics (n=3) of technical or clinical grade MMC (in pg) in 2 different, PLGA-based, drug delivery systems (DDSs) in time; PLGA-M_3% (crystalized) with technical grade MMC [prototype 5] and PLGA-M-_3% (crystalized) with clinical grade MMC [prototype 18],

Figure 11 is a schematic illustration of an example Drug Delivery System (DDS) located at an implantation site in the eye within sub-Tenons space 150 under the conjunctiva and Tenon’s Capsule in the eye.

Material and methods

Production of DDSs

An overview of seventeen different produced drug delivery systems (DDSs), containing MMC, is shown in Figure 1. Overall, there were 3 different designs: 1. film (f), 2. hamburger (H), and 3. meshwork (M). Hamburger (H) is a three-layer film consisting of two outer layers and an inner layer provided between the two outer layers according to the invention. Meshwork (M) is a mesh of fibers according to the invention.

The DDSs of Figure 1 were loaded with MMC of TCI (technical grade MMC) or Substipharm (clinical grade MMC) in solution (dissolved) or as solid particles (herein also referred as crystalized).

Comparative experiment: Films (1% MMC dissolved or as solid particles (technical grade))

A PCL-f or PLGA-f, containing dissolved MMC (technical grade), was produced via solvent casting.

For PCL (see prototype 6 in Figure 1), 135mg PCL was dissolved in 1mL chloroform (solution 1) and 1.44mg MMC in 0.5mL N,N-dimethylacetamide (solution 2) and both solutions were mixed. For PLGA (see prototype 7 in Figure 1), 170mg PLGA was dissolved in a solution of 1 ,44mg MMC in 4mL acetone.

The solution was poured into an aluminum tray and solvents were evaporated overnight at room temperature (RT) and thereafter in a vacuum oven at 50°C overnight.

The dried film was cut into small pieces and put in the carbon steel 1.1274 mold (Height: 0.3 mm, Whole diameter: 20mm). The mold was pressed for 1 min at 120 bar (for PCL) and for 4 min at 150 bar (for PLGA) at 65 °C. After this, the compression molding step was repeated until no air bubbles were visible anymore and the film looks homogeneously colored and translucent (twice or more times).

For a PCL-f containing MMC as solid particles (see prototype 8 in Figure 1), 135mg PCL was mixed with 1.44mg MMC.

For a PLGA-f containing MMC as solid particles (see prototype 9 in Figure 1), 170mg PLGA was mixed with 1.44mg MMC.

The polymer was premolded between two layers of aluminum foil (1 min at 120 bar for PCL and for 4 min at 150 bar for PLGA at 65°C) and cut into two pieces.

The MMC powder was added in between the two sheets and it was molded and cut again (twice or more times). The cut pieces were added to the carbon steel 1.1274 mold (Height: 0.3 mm, Whole diameter: 20mm). The mold was pressed for 1 min at 120 bar (for PCL) and for 4 min at 150 bar (for PLGA) at 65 °C. After this, the compression molding step was repeated once.

After compression molding, the films were removed from the mold and smaller discs of 3mm in diameter were made by using a 3mm manual pile cutter (for the PCL-f) and a laser cutter (settings: 75% intensity, 50% speed, 3 cycles, 1000 ppi, 0.9 mm depth cut, programmed diameter outer ring: 3.4 mm, programmed diameter hole: 0.28 mm) (for the PLGA-f).

Inventive example 1 : Hamburgers (0.3% MMC (technical grade))

A hamburger (H) of PCL or PLGA was made by using compression molding (see prototype 1 and prototype 2 in Figure 1). In brief, sufficient PCL (~140mg) or PLGA (~170mg) was placed in a carbon steel 1.1274 mold (Height: 0.3 mm, Whole diameter: 20mm). The mold was placed in a preheated (65 °C for PCL and 80 °C for PLGA) hydraulic press and pressed for 1 min at 120 bar (for PCL) and 4 min at 150 bar (for PLGA).

After this, the compression molding step was repeated until no air bubbles are visible anymore and the film looks homogeneously colored and translucent (twice or more times).

Thereafter, one more PCL- or PLGA-film was made.

Next, a thin PCL- or PLGA-film, containing MMC (technical grade), was produced via solvent casting as described above for prototype 6 and 7.

Finally, the three layered hamburger (polymer | polymer + MMC | polymer) was produced by compression molding. This was done by stacking the previously prepared films in the order of polymer-sheet (PCL or PLGA), polymer (PCL or PLGA) + MMC sheet, and polymer sheet (PCL or PLGA) in the carbon steel 1.1274 mold (Height: 0.9 mm, diameter: 20mm). Thereafter, the mold with sheets was pressed at 65 °C for 1 min at 120 bar for PCL, or for 4 min at 150 bar for PLGA.

The three-layered hamburgers were then removed from the mold and smaller discs of 3mm in diameter were made by using a 3mm manual pile cutter (for the PCL-H (see prototype 1 in Figure 1)) and a laser cutter (settings: 75% intensity, 50% speed, 3 cycles, 1000 ppi, 0.9 mm depth cut, programmed diameter outer ring: 3.4 mm, programmed diameter hole (for the in vivo prototypes): 0.28 mm) (for the PLGA-H (see prototype 2 in Figure 1)).

Inventive example 2: Meshworks (0.5%, 1%, 2%, or 3% MMC (technical or clinical grade))

A soft and loose fibrous meshwork of polymer with MMC (called “Meshwork” (M)) was produced via spraying technology. For a PCL-meshwork (PCL-M) with 2.1% (PCL- M_2.1%) dissolved MMC (see prototype 3 in Figure 1), 20mg MMC was dissolved in 1mL N,N-dimethylacetamide (DMA) and 672mg PCL in 25mL dichloromethane (DCM). Both solutions were mixed well and loaded into a spray gun. For a PCL-M_3% with the MMC loaded as solid particles (see prototype 13 (technical grade MMC) and prototype 17 (clinical grade MMC) in Figure 1), we first dissolved 400mg PCL in 12.5mL DCM and 2.5mL pentane. 12 mg MMC was then added to the polymer solution. For PCL-M_2% (see prototype 12 in Figure 1), 8mg MMC was added to the polymer solution; 4mg MMC was added to the polymer solution to make PCL- M_1% (see prototype 11 in Figure 1)).

In addition, for a PLGA-M_3% with MMC loaded as solid particles (see prototype 5 (technical grade MMC) and prototype 18 (clinical grade MMC) in Figure 1), 300mg Resomer® RG 756 S (Poly(D,L-lactide-co-glycolide) ester terminated, lactide:glycolide 75:25, Mw 76,000-115,000) and 100mg Resomer® RG 753 H (Poly(D,L-lactide-co-glycolide) acid terminated, lactide:glycolide 75:25, Mw 24, DOO- 35, 000) was dissolved in 3.175mL DCM. Then, 100pL ethyl lactate and 630pL pentane was added to the solution.

Thereafter, 12mg MMC was added to the polymer solution to make PLGA-M_3% (see prototype 5 (technical grade MMC) and prototype 18 (clinical grade MMC) in Figure 1); 8mg MMC was used for PLGA-M_2% (see prototype 15 in Figure 1),

4mg MMC was used for PLGA-M_1% (see prototype 14 (technical grade MMC) and prototype 19 (clinical grade MMC) in Figure 1), and

2mg MMC was added to the polymer solution to make DDS PLGA-M_0.5% (see prototype 20 in Figure 1)).

These polymer solutions were then loaded into a spray gun. After loading of the polymer solutions, containing MMC dissolved or as solid particles, into the spray gun, the meshwork was sprayed (keeping a distance between spray gun and target of approximately 20cm, a gas pressure of 1 bar nitrogen, the highest volume per time throughput and an angle of roughly 45° towards the side wall of the target).

The meshwork was placed in a vacuum oven overnight at 40 °C. Next, we punched 3 mm diameter discs out by using a 3mm pile cutter.

In addition, PLGA-M DDSs of 5 (prototype 19) and 7 mm (prototype 20) were made.

In vitro release studies and quantification analysis

The biodegradable polymers of the DDSs of Figure 1 are configured to dissolve or biodegrade in the presence of an aqueous fluid, such as aqueous humor, over time. Furthermore, the dissolution or biodegradation of the polymer over time releases the MMC of the DDSs over time. In vitro studies were carried out to study the biodegradation of the biodegradable polymers of the DDSs of Figure 1 in the presence of an aqueous fluid and the release of MMC of the DDSs over time. All the in vitro release studies used an aqueous fluid or elution buffer of 1X PBS (pH 7.4). DDSs (n = 3 or 4 of each prototype), all prototypes, were each placed in a well of a 12-wells plate with 1.5 mL elution buffer. The 12-wells plates with the devices were placed on an orbital shaker at 120 rpm in a 37°C incubator to mimic physiological conditions. For each sampling time point, the elution buffer was collected and replaced with fresh buffer. The collected samples were stored at - 80°C.

At the day of HPLC measurement, samples were thawed and diluted 1:5 in methanol. Concentration of the diluted MMC sample was measured using high performance liquid chromatography (HPLC; 1260 Infinity Quaternary LC System, Agilent Technologies, Santa Clara, CA, USA). A C8 reverse-phase column (Symmetry C8, 100A 5 Um, 4.6 mm x 250 mm; Waters) was used with a gradient of mobile phase A:B (83.5:16.5 in 25 minutes) with an isocratic delivery at 0.9 mL/min. The mobile phase A contained 25 mM sodium phosphate (pH 5.4 adjusted with 1 N sodium hydroxide) in deionized water and mobile phase B was 50% HPLC-grade methanol (VWR, Pennsylvania, USA) with 50% HPLC-grade acetonitrile (VWR, Pennsylvania, USA). Detection was done via absorbance at a wavelength of 365 nm.

The AUC of the MMC-peaks were analyzed by using the HPLC1 -software (Agilent T echnologies). The unknown concentration of the samples of each time-point was calculated by using also a standard curve of MMC (0-1500 pM) in each HPLC-run. The release rate at each time point was calculated by dividing the amount of drug collected by the duration between two time points. The cumulative release was calculated by making a sum of the release of each time-point. The release was also plotted in a percentage by dividing the cumulative value of a specific time-point by the amount of drug loaded in each DDS at the start of the experiment.

For UV/vis-experiments, PLGA-meshwork DDSs (1% technical MMC, ca. 20 mg) were added to 1 mL aqueous buffer solution and kept at 37°C. After the indicated times, the aqueous phase was removed, diluted to 3 mL and UV/vis-spectra were taken at a Perkin Elmer Lambda 750 UV-Vis-NIR spectrophotometer. The spectra were normalized at the maximum of the absorption band of MMC in water 365 nm. After removing the aqueous phase, the vials with the meshwork were refilled with 1 mL fresh buffer solution and kept at 37°C until the next time point.

Results

Three different DPS designs

The effect of the design on the release kinetics was evaluated by studying the differences between the prototypes PCL-f_1% (dissolved MMC) [prototype 6], PCL- H_0.3% (dissolved MMC) [prototype 1], and PCL-M_2.1% (dissolved MMC) [prototype 3], that all contain technical grade MMC (see Figure 2).

The data shows that the film released MMC very fast (within 1 day); the hamburger released MMC until day 25; and the meshwork released MMC until day 65. Therefore, the multilayer film and the mesh according to the invention allows a prolonged release of MMC.

The meshwork-DDS was soft and easy to handle with a forceps. Because of the softness, this DDS appears to be more gentle with less migration for the ocular tissues after implantation, in comparison to the more rigid hamburger-DDS.

Effect of dissolved vs solid particles MMC

The effect using MMC either in solution (dissolved) or as solid particles (crystalized), for the fabrication of the DDS was investigated by comparing MMC elution kinetics of the prototypes PCL-f_1% (dissolved) [prototype 6] vs PCL-f_1% (solid particles) [prototype 8], both containing technical grade MMC.

Data showed that the films, which were made with solid particles of MMC have a longer release of MMC (36 days) than the films made with dissolved MMC. The latter DDSs were empty after one day (Figure 4).

Next, we examined the absorption spectra of the aqueous elusion from PLGA DDSs fabricated either with the use of solid particles of MMC or dissolved MMC (UV/vis- experiments).

Figure 5 shows that numerous by- products are present in the eluent of the PLGA made with dissolved MMC, and their relative concentration increases over time. In contrast, the eluent of the DDS made with solid particles of MMC showed a spectrum much resembling that of pure MMC. Taken together, on the basis of these results on elution kinetics (see Figure 4) and stability (see Figure 5), the production process of using solid particles of MMC appeared more suitable than the production process using MMC which was dissolved in a solvent.

Polymer (PCL vs PLGA)

We studied whether degradation actually occurred in the DDSs that were used for measuring the in vitro elution kinetics. The DDSs that were used to study the elution kinetics in PBS were examined after 30-90 days (of immersion in PBS at 37°C; see M&M). While DDSs made of PCL maintained their shape, the PLGA DDSs slowly degraded.

In addition, the DDSs which were implanted in rabbit eyes were analyzed. While the PCL DDSs could be retrieved relatively unaffected, when studied macroscopically, the PLGA DDS was not intact anymore when the rabbit eye was dissected after 90 days at the end of the animal experiment.

Together these data indicate that the PLGA polymer has a better biodegradability.

Effect of the % of MMC vs polymer

The effect of the % of MMC vs polymer on the elution kinetics was investigated by making three comparisons:

First, we analyzed the differences between the prototypes PCL-M_3% (solid particles) [prototype 13] vs PCL-M_2% (solid particles) [prototype 12] vs PCL-M_1% (solid particles) [prototype 11] which all contained technical grade MMC (see Figure 6).

Second, we compared PLGA-M_3% (solid particles) [prototype 5] vs PLGA-M_2% (solid particles) [prototype 15] vs PLGA-M_1% (solid particles) [prototype 14] which all contained technical grade MMC (see Figure 7).

Third, we compared PLGA-M_3% (solid particles) [prototype 18] vs PLGA-M_1% (solid particles) [prototype 19] vs PLGA-M_0.5% (solid particles) [prototype 20] which all contained clinical grade MMC (see Figure 8). The data of the different PCL-M prototypes with 3%, 2%, and 1% MMC as solid particles (technical grade) showed that a higher % of MMC vs. polymer appeared to release faster than the prototypes with the lower % of MMC vs. polymer (see Figure 6).

However, no clear difference was observed between the PLGA-M prototypes with 3%, 2%, and 1% MMC as solid particles (technical grade) (see Figure 7). This result may be explained by batch differences of MMC.

In addition, there is an increased release of MMC between 36 and 56 days (see Figure 8), which may relate to the degradation of the PLGA DDS. The data of the different PLGA-M prototypes with 3%, 1%, and 0.5% MMC as solid particles (clinical grade) showed clearly that a higher % of MMC vs. polymer releases faster than the prototypes with a lower % of MMC vs. polymer (see Figure 8).

Overall, these results suggested that a higher % of MMC vs. polymer releases faster than a lower %. This allows for fine-tuning to achieve the desired release kinetics.

Effect of technical vs clinical MMC

The effect of the use of technical vs. clinical grade MMC as solid particles (solid particles) was investigated by observing the differences between

1. PCL-M_3% (solid particles) with technical grade MMC [prototype 13] vs PCL-M_3% (solid particles) with clinical grade MMC [prototype 17] (see Figure 9), and

2. PLGA-M_3% (solid particles) with technical grade MMC [prototype 5] vs PLGA- M_3% (solid particles) with clinical grade MMC [prototype 18] (see Figure 10).

The data showed that the use of technical grade MMC or clinical grade MMC, both in PCL-M_3% and PLGA-M_3%, had an effect on the release kinetics profile (see Figure 9 (for PCL-M_3%) and Figure 10 (PLGA-M_3%)).

In general, the prototypes with the clinical grade MMC released the MMC faster than the prototypes with the technical grade MMC.

An explanation may be that the additives are more water soluble (as they may be intended to help dissolving MMC in water). This would accelerate the dissolution of MMC out of the DDS. Furthermore, it leaves channels (additive is dissolved and hidden MMC is now exposed to water). Finally, the additives may also accelerate the degradation of the polymer.

Several prototypes were implanted in rabbits. Prototypes were implanted in the eyes of normotensive rabbits during a glaucoma filtration surgery. Preliminary results indicated that implanted DDSs did not give rise to strong adverse effects or toxicity.

Exemplary DDS

Figure 11 illustrates an example DDS 100 as described herein (in schematic form) located at an implantation site in the eye within sub-Tenons space 150 under the conjunctiva and Tenon’s Capsule in the eye. A glaucoma drainage tube or shunt 200 is implanted through a tissue passageway that extends from the sub-Tenons space 150 to the anterior chamber of the eye such that the distal end 205 of the tube 200 extends into the anterior chamber of the eye and the proximal end 210 of the tube lies in the sub-Tenons space 150. The glaucoma drainage tube or shunt 200 allows for drainage (or flow) of aqueous humor from the anterior chamber of the eye into the sub-Tenons space 150. In the presence of aqueous humor that flows into the sub-Tenons space 150, the DDS 100 biodegrades and releases MMC over time as described herein.