I 1111111111111111 11111 lllll lllll lllll lllll lllll lllll lllll 111111111111111111
`
`US009346814B2
`
`c12) United States Patent
`Jansen et al.
`
`(10) Patent No.:
`(45) Date of Patent:
`
`US 9,346,814 B2
`May 24, 2016
`
`(54) FAP INHIBITORS
`
`(56)
`
`References Cited
`
`(71) Applicants:UNIVERSITEIT ANTWERPEN,
`Antwerpen (BE); Fox Chase Cancer
`Center, Philadelphia, PA (US)
`
`(72)
`
`Inventors: Koen Jansen, Wilrijk (BE); Ingrid De
`Meester, Wilrijk (BE); Leen Heirbaut,
`Wilrijk (BE); Jonathan D Cheng,
`Philadelphia, PA (US); Jurgen Joossens,
`Wilrijk (BE); Koen Augustyns, Wilrijk
`(BE); Pieter Van Der Veken, Wilrijk
`(BE)
`
`(73) Assignees: Universiteit Antwerp, Antwerp (BE);
`Fox Chase Cancer Center,
`Philadelphia, PA (US)
`
`( *) Notice:
`
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U.S.C. 154(b) by O days.
`
`(21) Appl. No.:
`
`14/372,798
`
`(22) PCT Filed:
`
`Jan.17,2013
`
`(86) PCT No.:
`
`PCT /EP2013/050845
`
`§ 371 (c)(l),
`(2) Date:
`
`Jul. 17, 2014
`
`(87) PCT Pub. No.: WO2013/107820
`
`PCT Pub. Date: Jul. 25, 2013
`
`(65)
`
`Prior Publication Data
`
`US 2014/0357650Al
`
`Dec. 4, 2014
`
`(30)
`
`Foreign Application Priority Data
`
`Jan. 17,2012
`Nov. 14, 2012
`
`(GB)
`(GB)
`
`1200705.0
`1220458.2
`
`(51)
`
`(2006.01)
`(2006.01)
`(2006.01)
`(2006.01)
`(2006.01)
`(2006.01)
`
`Int. Cl.
`C07D 401112
`C07D 487104
`C07D403/12
`C07D413/12
`C07D417/12
`C07D 471104
`(52) U.S. Cl.
`CPC ............ C07D 487104 (2013.01); C07D 401112
`(2013.01); C07D 403112 (2013.01); C07D
`413112 (2013.01); C07D 417112 (2013.01);
`C07D 471104 (2013.01)
`( 58) Field of Classification Search
`CPC .. C07D 401/12; C07D 403/12; C07D 413/12;
`C07D 471/04; C07D 417/12; A61K 31/401
`See application file for complete search history.
`
`U.S. PATENT DOCUMENTS
`
`8,183,280 B2 *
`8,754,107 B2 *
`2011/0230462 Al
`
`5/2012 Evans et al. ................... 514/423
`6/2014 George et al. ................. 514/326
`9/2011 Hendricks et al.
`
`FOREIGN PATENT DOCUMENTS
`
`WO
`WO
`WO
`
`9532948
`2007085895 A2
`2010/083570 Al
`
`12/1995
`8/2007
`7/2010
`
`OTHER PUBLICATIONS
`
`International Preliminary Report on Patentability completed Mar. 28,
`2014 pertaining to International Application No. PCT/EP2013/
`050845 filed Jan. 17, 2013.
`International Search Report and Written Opinion completed Jun. 10,
`2013 pertaining to International Application No. PCT/EP2013/
`050845 filed Jan. 17, 2013.
`Database Registry (Online); Chemical Abstracts Service, Columbus,
`OH, US; Feb. 1, 2000; XP002695552; Database accession No.
`1097629-86-1.
`Nitz et al., "An Excursion into the Synthesis of Potential Angiotensin
`Converting Enzyme Inhibitors", The Journal of Organic Chemistry;
`vol. 47, No. 21, Oct. 1, 1982; pp. 4029-4032; XP055053192; ISSN:
`0022-3263, DOI: 10.1021/jo00142a005.
`Opacic et al., "The Novel L- and D-Amino Acid Derivatives of
`Hydroxyurea and Hydantoins: Synthesis, X-ray Crystal Structure
`Study, and Cytostatic and Antiviral Activity Evaluations", Journal of
`Medicinal Chemistry; vol. 48, No. 2, Jan. 1, 2005, pp. 475-482;
`XP0055053198; ISSN: 0022-2623, DOI: 10.1021/jm040869i.
`Suzuki et al, "Synthesis and Central Nervous System Actions of
`Thyrotropin-Releaseing Hormone Analogues Containing
`a
`Dihydroorotic Acid Moiety", Journal of Medicinal Chemistry,
`American Chemical Society, US, vol. 33, No. 8, Jan. 1, 1990, pp.
`2130-2137, XP002186256, ISSN: 0022-2623, DOI: 10.1021/
`JM00170A014.
`Acharya, et al., Fibroblast Activation Protein: A Serine Protease
`Expressed at the Remodeling Interface in Idiopathic Pulmonary
`Fibrosis, Human Pathology, 2006, vol. 37, pp. 352-360, USA.
`
`(Continued)
`
`Primary Examiner - D M Seaman
`(74) Attorney, Agent, or Firm - Dinsmore & Shohl LLP
`
`ABSTRACT
`(57)
`The present invention relates to novel inhibitors having high
`selectivity and specificity for FAP (fibroblast activation pro(cid:173)
`tein). Said inhibitors are useful as a human and/or veterinary
`medicine, in particular for the treatment and/or prevention of
`PAP-related disorders such as but not limited to proliferative
`disorders.
`
`13 Claims, No Drawings
`
`

`

`US 9,346,814 B2
`Page 2
`
`(56)
`
`References Cited
`
`OTHER PUBLICATIONS
`
`Brokopp, et al., Fibroblast Activation Protein is Induced by Inflam(cid:173)
`mation and Degrades Type 1 Collagen in Thin-Cap Fibroatheromata,
`European Heart Journal, doi: 10.1093/eurheartj/ehq519, 2011, pp.
`1-10, UK.
`Cheng, et al., Abrogation of Fibroblast Activation Protein Enzymatic
`Activity Attenuates Tumor Growth, Molecular Cancer Therapeutics,
`mct.aacrjournals.org, American Associate for Cancer Research,
`2005, pp. 351-361, USA.
`Dienus, et al., Increased Expression of Fibroblast Activation Protein(cid:173)
`Alpha in Keloid Fibroblasts: Implications for Development of a
`Novel Treatment Option, Arch Dermatol Res, 2010, vol. 302, pp.
`725-731, Springer, USA.
`Kelly, et al., Fibroblast Activation Protein-x: A Key Modulator of the
`Microenvironment in Multiple Pathologies, Chapter 3, Department
`of Pathology and Winthrop P. Rockefeller Cancer Institute, Univer(cid:173)
`sity of Arkansas for Medical Sciences, 2012, DOI: 10.1016/B978-0-
`12, pp. 83-116, USA.
`
`Kraman, et al., Suppression of Antitumor Immunity by Stromal Cells
`Expressing Fibroblast Activation Protein-x, www.sciencemag.org,
`Science, vol. 330, Nov. 5, 2010, pp. 827-830, UK.
`Laverman, et al., Immuno-PET and Immuno-SPECT of Rheumatoid
`Arthritis with Radio labeled Anti-Fibroblast Activation Protein Anti(cid:173)
`body Correlates with Severity of Arthritis, The Journal of Nuclear
`Medicine, vol. 56, No. 5, May 2015, pp. 778-784, Netherlands.
`Lee, et al., Enhancement of Fibrinolysis by Inhibiting Enzymatic
`Cleavage of Precursor x2-antiplasmin, 2011 International Society on
`of Thrombosis
`Thrombosis
`and Haemostasis,
`Journal
`andHaemostasis, vol. 9, pp. 987-996, USA.
`Loeffler, et al., Targeting Tumor-Associate Fibroblasts Improves
`Cancer Chemotherapy by Increasing Intratumoral Drug Uptake, The
`Journal of Clinical Investigation, vol. 116, No. 7, Jul. 2006, pp.
`1955-1962, Germany.
`Santos, et al., Targeting Fibroblast Activation Protein Inhibits Tumor
`Stromagenesis and Growth in Mice, The Journal of Clinical Investi(cid:173)
`gation, vol. 119, No. 12, Dec. 2009, pp. 3613-3625, USA.
`
`* cited by examiner
`
`

`

`US 9,346,814 B2
`
`1
`FAP INHIBITORS
`
`FIELD OF THE INVENTION
`
`The present invention relates to novel inhibitors having
`high selectivity and specificity for FAP (fibroblast activation
`protein). Said inhibitors are useful as a human and/or veteri(cid:173)
`nary medicine, in particular for the treatment and/or preven(cid:173)
`tion of PAP-related disorders such as but not limited to pro(cid:173)
`liferative disorders.
`
`BACKGROUND TO THE INVENTION
`
`1. Introduction
`Fibroblast activation protein (FAP, PAP-alpha, seprase,
`alpha2 antiplasmin converting enzyme) is a Clan SC protease
`of the prolyl oligopeptidase subfamily S9b, occurring as a cell
`surface homodimer. FAP has been demonstrated to possess
`both dipeptidyl peptidase and endopeptidase activity, cata(cid:173)
`lyzed by the same active center. Its expression is associated
`with activated stromal fibroblasts and pericytes of over 90%
`of human epithelial tumors examined and with normal or
`excessive wound healing, e.g. in tissue remodeling sites or
`during chronic inflammation. The enzyme is generally not
`expressed in normal adult tissues and in nonmalignant
`tumors. 1 Several studies have tried to map the physiological
`substrate spectrum of PAP, including very recent reports that
`identify i.a. alpha2-antiplasmin, type I collagen and gelatin as
`in vitro substrates of the endopeptidase activity of FAP.2
`Analogously, Neuropeptide Y, B-type natriuretic peptide,
`substance P and peptide YY have been identified as in vitro
`substrates of the dipeptidyl peptidase activity ofFAP. 3 None(cid:173)
`theless, the relevance of these findings under in vivo condi(cid:173)
`tions remains debatable and the unambiguous definition of
`FAP's physiological substrate spectrum remains untouched
`matter so far.
`Through structure-based design studies combined with
`extensive synthetic and biochemical effort, we were able to
`establish a Structure-Activity Relationship (SAR) ofN-acy(cid:173)
`lated aminoacyl pyrrolidine inhibitors of fibroblast activation
`protein. This has led to the discovery of a novel scaffold type
`that has the potential to deliver inhibitors of PAP that combine
`low nanomolar activity with unprecedented selectivity
`toward related Clan SC proteases (dipeptidyl peptidases IV, 45
`II, 8/9 and the endopeptidase prolyl oligopeptidase (PREP,
`PO). When compared to most other classes ofreported inhibi(cid:173)
`tors of FAP, inhibitors belonging to the scaffold type
`described here have remarkable stability both in aqueous
`solution and in human plasma and retain activity and selec- 50
`tivity for FAP within the latter media. For example,
`W02007085895, W02007005991, WO2010083570,
`WO2006125227 and WO0238590 all disclose FAP inhibitors
`having a general structure closely relating to the compounds
`of the present invention. However, none of them actually 55
`discloses compounds wherein
`
`2
`ticular said feature is relevant for providing the compounds of
`the present invention with the FAP activity and selectivity as
`defined herein.
`Based on FAP' s role in (patho-)fysiology, documented
`extensively in literature, we reasonably foresee potential
`applications of our inhibitors in disease domains character(cid:173)
`ised by: (a) proliferation (including but not limited to cancer)
`(b) tissue remodelling and/or chronic inflammation (includ(cid:173)
`ing but not limited to fibrotic disease, wound healing, keloid
`10 formation, osteoarthritis, rheumatoid arthritis and related dis(cid:173)
`orders involving cartilage degradation) and (c) endocrino(cid:173)
`logical disorders (including but not limited to disorders of
`glucose metabolism). The relationship of FAP with said
`15 pathological processes is described in more detail hereafter.
`(a) FAP and Proliferative Diseases (Including but not Limited
`to Cancer).
`During the last decade, numerous reports have been pub(cid:173)
`lished that claim an important role for F AP in tumor growth
`20 and proliferation. The exact mechanism by which FAP takes
`part in these processes is unknown, but direct modulation of
`tumor growth, angiogenesis or disease progression by pro(cid:173)
`teolytic processing of growth factors, cytokines, collagenase
`activity regulating proteins and even collagen derived pro-
`25 teins, is currently the subject of intensive research.
`While awaiting the detailed functional characterization of
`the enzyme in these processes, several groups currently focus
`on FAP's status as a potential cancer biomarker which pres(cid:173)
`ence or activity in tumors could also be used for site-directed
`30 delivery of oncology drugs.4 Equally important, FAP or its
`activity are being targeted by several groups as a direct way to
`reduce tumor growth and proliferation by means of immuno(cid:173)
`therapeutic and small molecule inhibitor approaches. 5 For the
`latter, a number of in vivo proof-of-concept studies are
`35 present. These all involve the dipeptide derived boronic acid
`talabostat (PT-100, Val-boroPro) or close analogues, and
`report significant activity on tumor stromagenesis and
`growth. 6 In addition, talabostat has been evaluated as a drug in
`various clinical trials up to phase II, for the treatment of, i.a.
`40 metastatic kidney cancer, chronic lymphocytary leukemia,
`pancreatic adenocarcinoma and non-small cell lung cancer.
`While talabostat in several of these trials was able to induce
`clinical response, questions were raised with regards to the
`safety profile of the compound, potentially related to its well(cid:173)
`known lack of selectivity with respect to other Subfamily S9B
`proteases.7
`(b) FAP and Diseases Involving Tissue Remodeling and/or
`Chronic Inflammation (Including but not Limited to Fibrotic
`Disease, Wound Healing, Keloid Formation, Osteoarthritis,
`Rheumatoid Arthritis and Related Disorders Involving Carti(cid:173)
`lage Degradation, Atherosclerotic Disease and Chron's Dis-
`ease)
`Multiple reports on occurrence of significantly increased
`FAP expression and/or activity both in physiological pro(cid:173)
`cesses and in several clearly distinct disease domains, indi(cid:173)
`cate that the enzyme might play an important role during
`events characterized by tissue remodeling and/or inflamma(cid:173)
`tion. Although the exact mechanism by which FAP is alleged
`to do so has to date not been clarified, the most straightfor-
`60 ward hypothesis involves the enzyme's capability of process(cid:173)
`ing collagenase activity regulating proteins and even collagen
`derived proteins, thereby altering the composition and struc(cid:173)
`ture of the extracellular matrix (ECM) of tissues. This effect
`could be supplemented by influences on the proteolytic pro-
`65 cessing of peptide growth factors and cytokines. Similar argu(cid:173)
`ments are summoned to describe the of FAP' s role in prolif(cid:173)
`erative disease (vide supra).
`
`0-•
`
`as defined in the present invention, is a 5 to 10-membered
`N-containing aromatic or non-aromatic mono- or bicyclic
`heterocycle, wherein there are exactly 2 ring atoms between
`the N atom and X. As further detailed herein below, in par-
`
`

`

`US 9,346,814 B2
`
`3
`Significant F AP expression has been confirmed for reactive
`fibroblasts in granulation tissue of healing wounds, on stellate
`cells at the tissue remodeling interface in hepatic cirrhosis,
`and in lung tissue in idiopathic pulmonary fibrosis. 8 For
`hepatic cirrhosis (the pathological state characterized by
`fibrosis in which FAP' s involvement has been best character(cid:173)
`ized) elevated expression of PAP was observed regardless of
`the etiology of the disease (viral hepatitis-induced, alcohol(cid:173)
`induced, biliary cirrhosis). This given might suggest broad
`applicability of PAP-targeted therapy, e.g. using small mol(cid:173)
`ecule inhibitors, in disease area's involving fibrotic liver
`degeneration. 9
`F AP expression was found to be significantly increased on
`keloid fibroblasts compared to normal skin fibroblasts and
`inhibition of FAP activity with the albeit unselective (with
`respect to phylogenetically related dipeptidyl peptidases)
`irreversible inhibitor Gly-ProCP)(OPh) 2 was found to lead to a
`decrease in invasiveness. 10
`FAP expression and activity was also shown to be associ(cid:173)
`ated with rheumatoid arthritis and osteoarthritis: PAP-activ(cid:173)
`ity on the surface of chondrocytes and elevated expression
`and activity in cartilage affected by osteoarthritis were dem(cid:173)
`onstrated. FAP was also found to be present in synovial tissue
`of affected joints, and elevated expression is detected in the
`murine collagen induced arthritis model. An additional path(cid:173)
`way by which FAP could be operating in the pathogenesis and
`progression of arthritis, has been proposed to imply pro(cid:173)
`teolytic cleavage of alpha2-antiplasmin, ultimately leading to
`fibrin deposition in the joint. Notably, in a Phase 1 clinical
`dosing study with a humanized anti-PAP antibody (sibrotu(cid:173)
`zumab) for advanced and metastatic cancer, the antibody in
`three patients not only localized to tumors, but also to the
`knees and shoulders. This observation has been connected to
`early-stage arthritis, offering initial support for the in vivo
`validation of FAP as a target for arthritis and related dis(cid:173)
`eases.II
`Recently, significantly increased expression of FAP was
`reported for human Type IV-Type V aortic atheromata, com(cid:173)
`pared to type III atheromata and healthy aortae. Additionally,
`thin-cap human coronary atheromata were found to contain
`more FAP than thick-cap lesions. The enzyme's occurrence
`was found to be concentrated on smooth muscle and endot(cid:173)
`helial cells, and it could not be detected on macrophages.
`Nonetheless, macrophage burden did correlate with total FAP
`expression in the plaques. Furthermore, in vitro zymography
`revealed that PAP-mediated collagenase activity was neutral(cid:173)
`ized by an antibody directed to the enzyme's catalytic domain
`both in human atherosclerotic smooth muscle cells and in
`fibrous caps of atherosclerotic plaques. 26
`In a very recent publication, FAP was found to be overex(cid:173)
`pressed in enteric strictures of patients with Chron' s disease
`(CD) and the protein was observed to be upregulated on
`strictured CD myofibroblasts by profibrogenic stimuli, lead(cid:173)
`ing the authors of this study to propose FAP as a potential
`target for the treatment of fibrostenosing CD. I2
`In general, no in vivo or clinical results (apart from the
`mentioned) have so far been disclosed dealing with the appli(cid:173)
`cation of PAP-targeting small molecules or immunotherapeu(cid:173)
`tic strategies in disease domains mentioned under this part.
`Nonetheless, mounting in vitro evidence from literature can
`certainly be considered compelling to initiate such investiga(cid:173)
`tions.
`(c) FAP and Diseases Involving Endocrinological Disorder
`(Including but not Limited to Disorders of Glucose Metabo(cid:173)
`lism) and Diseases Involving Blood Clotting Disorders.
`A recent patent application by Gorrell et al. claims the
`utility of FAP inhibitors in the prevention and treatment of
`
`4
`metabolic abnormalities characterized by abnormal glucose
`metabolism, including diabetes mellitus and new onset dia(cid:173)
`betes. This claim is however not otherwise documented in the
`literature. I3
`Finally, blocking the activity of the soluble form of FAP
`(alpha2-antiplasmin cleaving enzyme, APCE) occurring in
`plasma, using small molecule inhibitors was found to cause
`enhanced fibrinolysis and to lead to a decrease of plasmino(cid:173)
`gen activator induced clot lysis time. This observation led the
`10 authors to state thatAPCE-inhibition might constitute a novel
`approach in thrombolytic therapy without significant risk of
`bleeding. I4
`2. Inhibitor Design
`The prime aim underlying our effort to establish detailed
`15 SAR data for N-acylated aminoacyl pyrrolidine inhibitors of
`FAP, was to identify compounds with significantly improved
`(a) chemical stability and (b) selectivity characteristics when
`compared to known FAP inhibitors, while retaining high
`affinity for the target enzyme.
`20 (a) Limited chemical stability due to intramolecular cyclisa(cid:173)
`tion is a well known problem of several currently available
`highly potent dipeptide derived boronic acids ( e.g. Val-boro(cid:173)
`Pro ). This property, caused by the combined presence of a
`nucleophilic amino terminus and an electrophilic boronic
`25 acid, puts constraints e.g. on the applicability of this com(cid:173)
`pound and its analogues at physiological pH both in vitro and
`in vivo.I 5
`(b) Selectivity with respect to related S9b proteases (DPP IV,
`DPPS/9, DPP II, PREP) is a potential point of concern for all
`30 FAP inhibitors. Due to the high degree of phylogenetic rela(cid:173)
`tionship between the S9b proteases, pharmacophores of their
`inhibitors generally display substantial overlap. This problem
`is well documented for a number of described FAP inhibitors,
`including the well known ValboroPro. Noteworthy however,
`35 for most reported FAP inhibitors incomplete and in some
`cases even no selectivity data have been reported, rendering
`existing knowledge as a starting point for selective FAP
`inhibitor discovery inadequate. Nonetheless, taking into
`account the importance of inhibitor selectivity in the frame-
`40 work of potential compound toxicity and off-target effects,
`we deemed the preparation of selective compounds an impor(cid:173)
`tant goal of our endeavours. I
`With the number of reported PAP-inhibitors being small
`and most of them belonging to the class ofboronic acids, we
`45 initially decided to focus on compounds that contain a carbo(cid:173)
`nitrile warhead in place of the boronic acid, but conserve an
`overall dipeptide derived architecture. The latter is a hallmark
`of most chemotypes of published Subfamily S9B inhibitors.
`The carbonitrile function itself is also a popular affinity-
`50 enhancing moiety in reported series of inhibitors ofDPP IV,
`D PPS, D PP9 and PREP. Compared to other warheads that are
`used in serine protease inhibitor design (e.g. -B(OH)2 ,
`--CHO, chloromethylketones, ketoamides, ... ) the rela(cid:173)
`tively mildly electrophilic carbonitrile could account for
`55 making the inhibitor more selective in vivo, a hypothesis that
`has been raised in literature earlier. I In addition, the projected
`structures' overall architecture does in principle not impose
`fundamental limitations with respect to in vivo use, as e.g.
`illustrated by the EMA-approved vildagliptin and the FDA
`60 approved saxagliptin, both inhibitors ofDPP IV. Three other
`publications are known to us that also contain carbonitrile(cid:173)
`based inhibitors of FAP, all of them including incomplete
`FAP affinity and selectivity data or, in one case, even no
`affinity at all. I 6
`Using the boundary assumptions described above, we
`decided to start an in depth investigation of the Structure(cid:173)
`Activity Relationship (SAR) of N-acylaminoacyl(2-cyan-
`
`65
`
`

`

`US 9,346,814 B2
`
`5
`opyrrolidines) as inhibitors of FAP and their selectivity
`toward dipeptidyl peptidases and PREP. 1bree main struc(cid:173)
`tural fragments within this structure were marked for inves(cid:173)
`tigation and elaboration of the SAR:
`
`Val-boroPro
`talabostat
`
`Pl
`
`R3
`
`2
`
`~
`P3 I ,,)t..
`,1_
`I ....,.0
`
`R1
`
`N
`
`6
`
`5
`
`(c) The Pl Moiety:
`We decided to investigate the influence on activity and
`selectivity of substituting the pyrrolidine ring in compounds
`with structure 1. To this end, we selected a number of different
`functional groups with different bulk size and electronic
`effects.
`In addition, we expected the obtained SAR-information
`poised to be applicable to analogous inhibitor types contain(cid:173)
`ing specific other warhead types or even no warhead, a
`10 hypothesis that we later on showed to be correct.
`We have now surprisingly found that PAP-inhibitors of
`formula I exhibit good chemical stability and high selectivity
`for FAP, rendering them very suitable for the preparation of a
`15 medicine for the treatment of various PAP-related disorders.
`In addition, our invention has the potential to deliver com(cid:173)
`pounds with high solubility and low Log D-values, a feature
`that is far from evident for dipeptide-derived compounds
`lacking a basic amino terminus and that is accounted for by
`20 the presence ofheteroatoms introduced at specific positions
`of the P3 substituent.
`
`SUMMARY OF THE INVENTION
`
`25
`
`In a first aspect, the present invention provides a compound
`of Formula I or a stereoisomer, tautomer, racemic, metabolite,
`pro- or predrug, salt, hydrate, or solvate thereof,
`
`R2
`
`P2
`
`Generic structure of
`N-acyl-glycyl(2-cyano )pyrrolidines
`
`R1 - alkanoyl-, aryloyl-, arylalkanoyl, arybulfonyl, .
`R2 ~ alkyl-, aryl-, arylalkyl, .
`R3 = methyl-, ethyl-, methylideen-, fluoro-, difluoro-, .
`
`30
`
`35
`
`40
`
`(a) the P3 Moiety:
`By attaching this moiety (via an acyl linkage) to the ami(cid:173)
`noacyl(2-cyanopyrrolidine) backbone of the inhibitor, we
`wanted to make the P2 residue non-basic and non-nucleo-
`philic, thus increasing the likeliness of inhibitor selectivity
`and higher stability with respect to the S9b dipeptidyl pepti(cid:173)
`dases. Some literature evidence existed for peptide derived
`boronic acid inhibitors that this approach might be viable,
`although no systematic studies in this direction have been 45
`carried out. In addition, a substantial number of these litera(cid:173)
`ture FAP inhibitors have been reported with only limited or
`even without selectivity data for the related dipeptidyl pepti(cid:173)
`dases. Additionally, while one might anticipate affinity
`toward dipeptidyl peptidases to be smaller, blocking the 50
`amino terminus does substantially increase the risk of selec(cid:173)
`tivity problems with respect to the endopeptidase PREP.
`Again, very limited literature information was present deal-
`ing with FAP to PREP selectivity of inhibitors with an acy(cid:173)
`lated P2 amine function. 1
`(b) the P2 Moiety:
`while several acylated glycyl(2-borono )pyrrolidines have
`been reported in literature, almost no data exist on the influ(cid:173)
`ence of other amino acid residues at the P2 position in acy- 60
`lated compounds. At the outset of our activities, substrate
`kinetics studies nonetheless indicated a rather strict prefer(cid:173)
`ence of PAP for a P2-glycine residue in substrates containing
`an acy lated P2 amino function. This given is in sharp contrast
`with a series of dipeptide-derived substrates and/or inhibitors 65
`( e.g. ValboroPro) with a free amino terminus, where the num-
`ber of tolerated P2 residues is known to be much larger.
`
`55
`
`Wherein
`R 1 and R2 are each independently selected from the group
`comprising -H, OH, -halo, C 1_6alkyl, ---O-C 1_6alkyl,
`S-C 1_6alkyl;
`R3 is selected from the group comprising -H, -CN,
`-B(OH)2 , ----C(O)alkyl, -C(O)aryl-, ----C=C----C(O)
`-C=C-S(0)2 aryl,
`----C02 H,
`-S03 H,
`aryl,
`-S02NH2 , -P03H2 , and 5-tetrazolyl;
`R4 is selected from the group comprising -H, -C 1_6alkyl,
`-0----C 1 _6alkyl, -S----C 1 _6alkyl, -Ari, and ----C 1 _6
`aralkyl; each of said ----C 1 _6alkyl being optionally substi(cid:173)
`tuted with from 1 to 3 substituents selected from -OH,
`-halo
`R5 , R6 and R7 are each independently selected from the group
`-oxo,
`comprising -H, -OH,
`-halo, -C 1_6alkyl,
`-0----C 1 _6alkyl, -S-C 1_6alkyl, -NR8R9 ,
`---OR12
`-Het2 and -Ar2 ; each of said C 1 _6alkyl being optionally
`substituted with from 1 to 3 substituents selected from
`-OH, -halo
`R8 , R9 and R 12 are each independently selected from the
`group comprising -H, -OH, -halo, -C 1_6alkyl,
`-0----C 1 _6alkyl, -S-C 1_6alkyl, and-Ar3
`R 10 , Ru, R 13 and R14 are each independently selected from
`the group comprising -H, -OH, -halo, -C 1_6alkyl,
`-0----C 1 _6alkyl, and -S----C 1_6alkyl;
`Ar1 , Ar2 andAr3 are each independently a 5- or 6-membered
`aromatic monocycle optionally comprising 1 or 2 heteroa(cid:173)
`toms selected from 0, N and S; each of said Ar1 , Ar2 and
`Ar3 being optionally and independently substituted with
`
`

`

`US 9,346,814 B2
`
`nis 0;
`
`8
`
`0-•
`
`7
`from 1 to 3 substituents selected from -NR10R 1 i, ----C 1 _6
`alkyl, -O----C 1 _6alkyl, -S-C 1_6alkyl;
`Het2 is a 5- or 6-membered non-aromatic monocycle option(cid:173)
`ally comprising 1 or 2 heteroatoms selected from 0, N and
`S; said Het2 being optionally substituted with from 1 to 3
`substituents selected from -NR13R14, -C 1_6alkyl,
`---0----C 1 _6alkyl, -S-C 1_6alkyl;
`n is 0, 1, 2, or 3
`
`0-·
`
`represents a 5 to IO-membered N-containing aromatic or
`10 non-aromatic mono- or bicyclic heterocycle, wherein there
`are exactly 2 ring atoms between the N atom and X; said
`heterocycle optionally further comprising 1, 2 or 3 heteroat(cid:173)
`oms selected from 0, N and S; and
`X represents a C atom
`The current invention further provides a compound of For-
`mula II or a stereoisomer, tautomer, racemic, metabolite, pro(cid:173)
`or predrug, salt, hydrate, or solvate thereof,
`
`15
`
`II
`
`25
`
`represents a 5 to IO-membered N-containing aromatic or
`non-aromatic mono- or bicyclic heterocycle, wherein there
`are exactly 2 ring atoms between the N atom and X; said
`heterocycle optionally further comprising 1, 2 or 3 heteroat- 20
`oms selected from 0, N and S; and
`X represents a C atom
`In a preferred embodiment, the present invention provides
`a compound according to formula I, wherein
`R 1 and R2 are each independently selected from the group
`comprising -H, and -halo;
`R3 is -CN, or -B(OH)2
`R4 is selected from the group comprising-H or-C 1_6alkyl; 30
`each of said ----C 1 _6alkyl being optionally substituted with
`from 1 to 3 substitucnts selected from -OH;
`Rs, R6 and R7 are each independently selected from the group
`comprising -H, -OH, -oxo,
`-halo, -C 1_6alkyl,
`---0----C 1 _6alkyl, Ar2 and-NRsR9 ; each of said C 1 _6alkyl
`being optionally substituted with from 1 to 3 substituents
`selected from -OH, -halo;
`Rs and R9 are each independently selected from the group
`comprising-Hand -Ar3
`Ar2 and Ar3 are each independently -phenyl optionally sub(cid:173)
`stituted with from 1 to 3-O----C 1 _6alkyl;
`n is O or 1
`
`wherein
`R 1 and R2 are each independently selected from the group
`comprising -H, OH, -halo, C 1_6alkyl, ---O-C 1_6alkyl,
`S-C 1_6alkyl;
`R3 is selected from the group comprising -H, -CN,
`-B(OH) 2 , ----C(O)alkyl, -C(O)aryl-, ----C=C----C(O)
`-C=C-S(O)2 aryl,
`----CO2 H,
`-SO3 H,
`aryl,
`-SO2NH2 , -PO3H2 , and 5-tetrazolyl
`35 R4 is selected from the group comprising -H, -C 1_6alkyl,
`-O----C 1 _6alkyl, -S----C 1 _6alkyl, -Ari, and ----C 1 _6
`aralkyl; each of said ----C 1 _6alkyl being optionally substi(cid:173)
`tuted with from 1 to 3 substituents selected from -OH,
`-halo
`40 Rs, R6 and R7 are each independently selected from the group
`-oxo,
`comprising -H, -OH,
`-halo, -C 1_6alkyl,
`-O----C 1 _6alkyl, -S----C 1 _6alkyl, -NRsR9 , and -Ar2 ;
`each of said C 1_6alkyl being optionally substituted with
`from 1 to 3 substituents selected from -OH, -halo
`45 Rs and R9 , R 10 and R 11 are each independently selected from
`the group comprising -H, -OH, -halo, -C 1_6alkyl,
`-O----C 1 _6alkyl, and -S----C 1_6alkyl;
`R 10 and R 11 are each independently selected from the group
`comprising -H, -OH, -halo, -C 1_6alkyl, -O----C 1 _6
`alkyl, -S----C 1_6alkyl, and-Ar3 ;
`Ar1 , Ar2 andAr3 are each independently a 5- or 6-membered
`aromatic monocycle optionally comprising 1 or 2 heteroa(cid:173)
`toms selected from 0, N and S; each of said Ar 1, andAr2
`being optionally and independently substituted with from 1
`to 3 substituents selected from -NR10R 11 , -C 1_6alkyl,
`-O----C 1 _6alkyl, -S-C 1_6alkyl;
`n is 0, 1, 2, or 3
`mis 1 or 2
`
`0-•
`
`50
`
`55
`
`represents a 5 to IO-membered N-containing aromatic or
`non-aromatic mono- or bicyclic heterocycle, wherein there
`are exactly 2 ring atoms between the N atom and X; said
`heterocycle optionally further comprising 1, 2 or 3 heteroat(cid:173)
`oms selected from 0, N and S; and
`X represents a C atom
`In yet another preferred embodiment, the present invention
`provides a compound according to formula I, wherein
`R 1 and R2 are each independently selected from the group 60
`comprising -H, and -F;
`R3 is -CN, and -B(OH)2
`R4 is-H;
`Rs, R6 and R7 are each independently selected from the
`group comprising -H, -oxo, -halo, ----C 1 _6alkyl, and
`-O----CF3 ;
`
`65 represents a 5 to 6-membered N-containing aromatic or non(cid:173)
`aromatic monocyclic heterocycle optionally further compris(cid:173)
`ing 1 or 2 heteroatoms selected from 0, N and S.
`
`

`

`10
`
`Illa
`
`Illb
`
`US 9,346,814 B2
`
`9
`In a preferred embodiment, the current invention provides
`a compound according to formula II, wherein
`R 1 and R2 are each independently selected from the group
`comprising -H, OH, -halo, C 1 _6alkyl, ---O-C 1_6alkyl,
`S-C 1_6alkyl;
`R3 is selected from the group comprising -H, ----CN, and
`-B(OH) 2
`R4 is-H;
`Rs, R6 and R7 are each independently selected from the group
`-halo, -C 1_6alkyl, 10
`comprising -H, -OH, -oxo,
`---0----C 1 _6alkyl, -S----C 1 _6alkyl, -NR8R9 , and -Ar2 ;
`each of said C 1 _6alkyl being optionally substituted with
`from 1 to 3 substituents selected from -OH, -halo
`R8 , R9 , R 10 and R 11 are each independently selected from the 15
`group comprising -H, -OH, -halo, -C 1_6alkyl,
`---0----C 1 _6alkyl, and -S----C 1 _6alkyl;
`Ar2 is a 5- or 6-membered aromatic monocycle optionally
`comprising 1 or 2 heteroatoms selected from 0, N and S;
`Ar2 being optionally and independently substituted with 20
`from 1 to 3 substituents selected from -NR10R 1 i, ----C 1 _6
`alkyl, -O----C 1 _6alkyl, -S-C 1_6alkyl;
`n is 0, 1, 2, or 3
`mis 1 or 2
`
`25
`
`is a 5- or 6-membered aromatic or non-aromatic monocylic
`heterocycle optionally further comprising 1 or 2 heteroatoms
`selected from 0, N and S; selected from the list comprising
`
`N~ •
`
`,,
`
`I
`
`N-N
`
`30 wherein
`R 1 and R2 are each independently selected from the group
`comprising -H, OH, -halo, C 1_6alkyl, ---O-C 1_6alkyl,
`S-C 1_6alkyl;
`35 R3 is selected from the group comprising -H, -CN,
`-B(OH) 2 , ----C(O)alkyl, -C(O)aryl-, ----C=C----C(O)
`aryl,
`-C=C-S(O)2 aryl,
`----CO2 H,
`-SO3 H,
`-SO2NH2 , -PO3H2 , and 5-tetrazolyl
`40 R4 is selected from the group comprising -H, -C 1_6alkyl,
`-O----C 1 _6alkyl, -S----C 1 _6alkyl, -Ari, and ----C 1 _6
`aralkyl; each of said ----