US 20150202317A1 (19) United States (12) Patent Application Publication (10) Pub. No.: US 2015/0202317 A1 Rau et al. (43) Pub. Date: Jul. 23, 2015 (54) DIPEPTDE-BASED PRODRUG LINKERS Publication Classification FOR ALPHATIC AMNE-CONTAINING DRUGS (51) Int. Cl. A647/48 (2006.01) (71) Applicant: Ascendis Pharma A/S, Hellerup (DK) A638/26 (2006.01) A6M5/9 (2006.01) (72) Inventors: Harald Rau, Heidelberg (DE); Torben A 6LX3/553 (2006.01) Le?mann, Neustadt an der Weinstrasse (52) U.S. Cl. (DE) CPC ......... A61K 47/48338 (2013.01); A61 K3I/553 (2013.01); A61 K38/26 (2013.01); A61 K (21) Appl. No.: 14/674,928 47/48215 (2013.01); A61M 5/19 (2013.01) (22) Filed: Mar. 31, 2015 (57) ABSTRACT The present invention relates to a prodrug or a pharmaceuti Related U.S. Application Data cally acceptable salt thereof, comprising a drug linker conju (63) Continuation of application No. 13/574,092, filed on gate D-L, wherein D being a biologically active moiety con Oct. 15, 2012, filed as application No. PCT/EP2011/ taining an aliphatic amine group is conjugated to one or more 050821 on Jan. 21, 2011. polymeric carriers via dipeptide-containing linkers L. Such carrier-linked prodrugs achieve drug releases with therapeu (30) Foreign Application Priority Data tically useful half-lives. The invention also relates to pharma ceutical compositions comprising said prodrugs and their use Jan. 22, 2010 (EP) ................................ 10 151564.1 as medicaments. US 2015/0202317 A1 Jul. 23, 2015 DIPEPTDE-BASED PRODRUG LINKERS 0007 Alternatively, the drugs may be conjugated to a car FOR ALPHATIC AMNE-CONTAINING rier through permanent covalent bonds. This approach is DRUGS applied to various classes of molecules, from So-called Small molecules, through natural products up to larger proteins. 0001. The present application is a continuation of U.S. patent application Ser. No. 13/574,092 filed on Jul.19, 2012, 0008 Liraglutide is an example of a peptide drug that which claims priority from PCT Patent Application No. PCT/ achieves an extended half-life by permanent covalent modi EP2011/050821 filed on Jan. 21, 2011, which claims priority fication with a palmitoyl moiety. The fatty acid alkyl chain from European Patent Application No. EP 10 151564.1 filed serves to provide albumin binding in Vivo and the palmitoy on Jan. 22, 2010, the disclosures of which are incorporated lated peptide forms an albumin complex that acts as a drug herein by reference in their entirety. reservoir in the blood stream. 0009 Albuferon is an example of a protein drug that FIELD OF THE INVENTION achieves an extended half-life by permanent covalent modi fication with another protein that in itself has a long half-life. 0002 The present invention is directed to carrier-linked The corresponding fusion protein of albumin and interferon prodrugs having temporary amide linkages between Substi alpha, Albuferon, exhibits a significantly extended half-life as tuted dipeptide moieties and aliphatic amine groups of bio compared to interferon alpha. logically active entities such as peptides, proteins, natural 0010 Many small molecule medicinal agents, like alka products or synthetic chemical compounds. Such carrier loids and anti-tumor agents, show low solubility in aqueous linked prodrugs are characterized by slow release of unmodi fluids. One way to solubilize these small molecule com fied biologically active entity. pounds is to conjugate the Small molecule compounds to 0003. It is noted that citation or identification of any docu hydrophilic (water-soluble) polymers. A variety of water ment in this application is not an admission that such docu soluble polymers, such as human serum albumin, dextran, ment is available as prior art to the present invention. lectins, poly(ethylene glycol) (PEG), poly(styrene-co-maleic 0004 Typically, carriers employed for extended time-ac anhydride), poly(N-hydroxypropylmethacrylamide), poly tion engineering in drug delivery are either used in a non (divinyl ether-co-maleic anhydride), hyaluronic acid have covalent fashion, with the drug physicochemically formu been described for this purpose (R. Duncan, Nature Rev. Drug lated into a solvent-carrier mixture, or by permanent covalent Disc., 2003, 2, 347-360). attachment of a carrier reagent to one of the drug's functional 0011 Covalent modification of biological molecules with groups. poly(ethylene glycol) has been extensively studied since the 0005. Non-covalent drug encapsulation into polymeric late 1970s. So-called PEGylated proteins have shown carriers has been applied to depot formulations for long improved therapeutic efficacy by increasing solubility, reduc acting release profiles. Typically, the drug is mixed with car ing immunogenicity, and increasing circulation half-live in rier material and processed in Such fashion, that the drug Vivo due to reduced renal clearance and proteolysis by becomes distributed inside the bulk carrier. For instance poly mer-drug aggregates may be shaped as microparticles which enzymes (see, for example, Caliceti P., Veronese F. M., Adv. are administered as an injectable Suspension or the polymer Drug Deliv. Rev. 2003, 55, 1261-1277). drug aggregates are formulated as gels which are adminis 0012 However, many biological molecules such as IFN tered in a single bolus injection. Known in the art are also alfa 2, saquinavir or Somatostatin are inactive or show liposomal formulations, where the carrier may be a polymeric decreased biological activity when a carrier is covalently or non-polymeric entity capable of Solubilizing the drug. conjugated to the drug (T. Peleg-Shulman et al., J. Med. Drug release occurs when the carrier Swells or physically Chem., 2004, 47, 4897-4904). deteriorates or chemical degradation allows diffusion of the 0013. In order to avoid shortcomings imposed by either drug to the exterior and Subsequently into the biological envi the non-covalent polymer mixtures or the permanent covalent ronment. Such chemical degradation processes may be auto attachment, it may be preferable to employ a prodrug hydrolytic or enzyme-catalyzed. An example for a marketed approach for chemical conjugation of the drug to the polymer drug based on bolus administration of a drug-polymer gel is carrier. In Such polymeric prodrugs, the biologically active Lupron Depot. An example for a marketed drug based on moieties (drugs, therapeutic, biological molecule, etc.) are Suspended microparticles is Nutropin Depot. An example for typically linked to the polymeric carrier moiety by a tempo a marketed drug based on a liposomal formulation is DOXil. rary bond formed between the carrier moiety and a hydroxy, 0006. A disadvantage of the non-covalent approach is that amino or carboxy group of the drug molecule. in order to prevent uncontrolled, burst-type release of the 0014 Prodrugs are therapeutic agents that are almost inac drug, encapsulation of the drug has to be highly efficient by tive perse but are predictably transformed into active molecu creating a sterically highly crowded environment. Restrain lar entities (see B. Testa, J. M: Mayer in Hydrolysis in Drug ing the diffusion of an unbound, water Soluble drug molecule and Prodrug Metabolism, Wiley-VCH, 2003, page 4). The requires strong van der Waals contacts, frequently mediated carrier prodrug approach may be applied in Such a fashion through hydrophobic moieties. Many conformationally sen that the drug is released in vivo from the polymer in order to sitive drugs, such as proteins or peptides, are rendered dys regain its biological activity. The reduced biological activity functional during the encapsulation process and/or during of the prodrug as compared to the released drug is of advan Subsequent storage of the encapsulated drug. In addition, tage if a slow or controlled release of the drug is desired. In Such amino-containing drugs readily undergo side reactions this case, a relatively large amount of prodrug may be admin with carrier degradation products (see, for example, D. H. Lee istered without concomitant side effects and the risk of over et al., J. Contr. Rel., 2003, 92,291-299). Furthermore, depen dosing. Release of the drug occurs over time, thereby reduc dence of the release mechanism of the drug upon biodegra ing the necessity of repeated and frequent administration of dation may cause interpatient variability. the drug. US 2015/0202317 A1 Jul. 23, 2015 00.15 Prodrug activation may occur by enzymatic or non nucleophilicity as compared to hydroxylic or phenolic enzymatic cleavage of the temporary bond between the car groups. This is particularly true for proteins and peptides rier and the drug molecule, or a sequential combination of which may contain a great variety of different reactive func both, i.e. an enzymatic step followed by a non-enzymatic tionalities, where non-selective conjugation reactions lead to rearrangement. In an enzyme-free in-vitro environment Such undesired product mixtures which require extensive charac as an aqueous buffer Solution, a temporary bond such as an terization or purification and may decrease reaction yield and ester oramide may undergo hydrolysis, but the corresponding therapeutic efficiency of the product. rate of hydrolysis may be much too slow and thus outside the 0022 Amide bonds are usually much more stable against therapeutically useful range. In an in vivo environment, hydrolysis than ester bonds, and the rate of clevage of the esterases or amidases are typically present and the esterases amide bond would be too slow for therapeutic utility in a and amidases may cause significant catalytic acceleration of carrier-linked prodrug. Therefore it is advantageous to add the kinetics of hydrolysis from twofold up to several orders of structural chemical components such as neighbouring groups magnitude (see, for example, R. B. Greenwald et al. J. Med. in order to exert control over the cleavability of the prodrug Chem. 1999, 42 (18), 3857-3867). amide bond. Such additional cleavage-controlling chemical 0016 Prodrugs fall in two classes, bioprecursors and car structures that are provided neither by the carrier entity nor by rier-linked prodrugs.