Inhibitors and Their Uses

The present invention relates to inhibitors of PPP1 R15A and PPP1 R15B and their use in therapy.

Background to the Invention

The reversible phosphorylation of proteins controls virtually all aspects of cell and organismal function, allowing cells to adapt to sudden changes through the antagonistic action of kinases and phosphatases. Consequently, targeting phosphorylation offers a broad range of therapeutic opportunities and kinases have arisen as the most prevalent drug targets in today's pharmaceutical research with more than 3000 approved and experimental drugs. However, while targeting phosphatases should in principle be as attractive as kinases, the therapeutic potential of phosphatases has been overlooked. The majority of protein phosphorylation occurs on serine and threonine and selective serine/threonine dephosphorylation is achieved by hundreds of different dimeric or trimeric holoenzymes assembled from one of only a few catalytic subunits combined with one amongst hundreds of diverse regulatory subunits (Heroes et al., FEBS Journal, 280, 584-595, 2012). Thus, inhibition of the catalytic component of the holoenzyme such as PP1c results in inhibition of hundreds of phosphatases and is toxic. Since selectivity is an important property for drug development, the promiscuity of catalytic phosphatases has led them to acquire the reputation of being undruggable.

Phosphorylation of the a subunit of elF2a is the first line of defense against a variety of stresses and is thereby a central component of two partly overlapping signaling pathways: the Unfolded Protein Response (UPR) and the Integrated Stress Response (ISR). To reverse elF2a phosphorylation, mammalian cells have two elF2a phosphatases. The elF2a phosphatases are dimeric holoenzymes that share a catalytic subunit PP1c with about 200 other phosphatases, and are bound to one of two related regulatory subunits: PPP1 R15A (Novoa et al., The Journal of Cell Biology, 153, 1345-1355, 2001), a stress inducible protein or PPP1 R15B, which is constitutively expressed (Jousse et al., The Journal of Cell Biology, 163, 767-775, 2003).

Recently, the feasibility of inhibiting selectively a serine/threonine phosphatase has been demonstrated. Guanabenz (Tsaytler et al., Science, 332, 91-94, 201 1 ; Tsaytler and Bertolotti, FEBS Journal, 280, 766-770, 2012) and its derivatives, some of which are disclosed in WO2014108520 (Medical Research Council), were found to selectively inhibit PPP1 R15A/GADD34, a stress-induced regulatory subunit of the serine/threonine protein phosphatase 1 , and was proposed as a treatment for diseases associated with protein misfolding stress.

PPP1 R15A inhibition selectively inhibits the stress-induced elF2a phosphatase composed of PPP1 R15A and PP1 , while sparing the highly related and constitutive phosphatase

PPP1 R15B-PP1. PPP1 R15A inhibition prolongs elF2a phosphorylation in stressed cells and this results in prolonging translation attenuation in stressed cells. As a consequence, chaperone availability is increased in stressed cells because the chaperones that are normally engaged in assisting the folding of newly synthetized proteins become available when translation is decreased. This favors protein folding and rescues cells from protein proteostasis defects. Thus, in principle, PPP1 R15A inhibitors could treat mammalian diseases involving protein misfolding stress. Inhibition of PPP1 R15A in mammals has an attractive therapeutic potential because inhibition of PPP1 R15A is predicted to be safe as PPP1 R15A/GADD34 knock-out mice are largely indistinguishable from wild-type mice (Marciniak et al., Genes & Development, 78, 3066-3077, 2004). However, the number of therapeutic indications that can be treated with PPP1 R15A inhibitors is predicted to be restricted to diseases where PPP1 R15A is expressed and where PPP1 R15A is in the disease mode of action. Thus, inhibition of PPP1 R15A may be powerful and safe but will be restricted to diseases involving PPP1 R15A.

Regardless of the limitations associated with PPP1 R15A inhibition, the approach of restoring proteostasis by fine tuning translation to increase chaperone availability is in theory powerful, straightforward and applicable to correct a broad range of diseases involving misfolded proteins. As noted above, the use of PPP1 R15A inhibitors will be restricted to diseases where PPP1 R15A is expressed and where PPP1 R15A is in the disease mode of action. This represents a serious limitation. Thus alternative approaches, of broad therapeutic potential, are needed and the present invention seeks to provide these.

Summary of the Invention

Compounds which inhibit PPP1 R15A and PPP1 R15B can advantageously be used to treat a wider range of diseases than compounds which selectively inhibit PPP1 R15A.

In a first aspect, the present invention provides compounds of formula IA:

(ΙΑ)

or a pharmaceutically acceptable salt thereof, wherein:

Xa is N or CR2a;

Ya is N or CR4a;

R1a is H, F, CI or Br;

R2a Rsa R4a R5a egch jnc|epenc|entiy represent H, F or CI;

with the proviso that:

when Xa and Ya represent CR2a and CR4a respectively and R2a and R4a are both H:

R1a is not F, CI or Br when R3a and R5a both represent H;

R5a is not F or CI when R1a is CI and R2a is H;

R3a is not F when R1a is CI and R5a is H;

R3a is not CI when R1a and R5a are both H or when R1a is CI and R5a is H;

R1a, R3a and R5a are not all H;

R1a is not CI when R3a is H and R5a is F;

when Xa represents CH and Ya represents CR4a wherein R4a is CI:

R1a and R5a are not both CI;

R3a is not CI when R1a and R5a are CI;

when Xa represents CR2a and Ya represents CR4a and R2a and R4a are both CI, R1a, R3a and R5a are not all H.

In one embodiment, Xa represents CR2a and Ya represents CR4a, wherein R2a and R4a each independently represent H, F or CI.

In one embodiment, three of R1a, R2a, R3a, R4a and R5a represent CI or F and two of R1a, R2a R3a, R4a and R5a represent H, optionally wherein at least one of R1a, R2a, R3a, R4a and R5a is F.

In one embodiment, three of R1a, R2a, R3a, R4a and R5a represent CI and two of R1a, R2a, R3a, R4a and R5a represent H.

In one embodiment, R3a is CI or F and R1a, R2a, R4a and R5a are independently selected from H, F and CI, wherein two of R1a, R2a, R4a and R5a are selected from F and CI and two of R1a, R2a, R4a and R5a is H.

In one embodiment, R5a is H.

In one embodiment, the compound of formula IA is in the E-isomer form.

A second aspect of the invention relates to com ounds of formula IB:

(IB)

or a pharmaceutically acceptable salt thereof, wherein:

Xb is N or CR2b;

Yb is N or CR4b;

R1 b is H, F, CI or Br;

R2b R3b R4b Rsb egch independently represent H, F or CI;

with the proviso that:

when Xb and Yb both represent N, R1 b and R3b are not both CI;

R1 b is not Br when Xb is CR2b and R2b is CI;

when R3b and R4b are both H, R1 b and R2b are not both CI;

when Xb is CR2b and R2b and R3b are both H, R1 b is not CI when Yb is CR4b and R4b is F; when Xb is CR2b and Yb is CR4b, R1 b, R2b, R3b, R4b and R5b are not all H;

when Xb is CR2b and Yb is CR4b and R2b, R3b, R4b and R5b are H, R1 b is not CI;

when Xb is CR2b and Yb is CR4b and R2b, R3b and R4b are H, R1 b is not CI when R5b is F; for use in the treatment of a disease state alleviated by the inhibition of PPP1 R15A and

PPP1 R15B.

In one embodiment, Xb represents CR2b and Yb represents CR4b, wherein R2b and R4b each independently represent H, F or CI.

In one embodiment, three of R1 b, R2b, R3b, R4b and R5b represent CI and two of R1 b, R2b, R3b, R4b and R5b represent H.

In one embodiment, three of R1 b, R2b, R3b, R4b and R5b represent CI or F and two of R1 b, R2b, R3b, R4b and R5b represent H, optionally wherein at least one of R1 b, R2b, R3b, R4b and R5b is F.

In one embodiment, R3b is CI or F and R1 b, R2b, R4b and R5b are independently selected from H, F and CI, wherein three of R1 b, R2b, R4b and R5b are selected from F and CI and one of R1 b, R2b, R4b and R5b is H.

In one embodiment, R5a is H.

In one embodiment, the compound of formula IB is in the E-isomer form.

A further aspect of the invention relates to compounds of formula IA for use in therapy.

A further aspect of the invention relates to compounds of formula I A or formula IB for use in the treatment of a disease state alleviated by the inhibition of PPP1 R15A and PPP1 R15B.

A further aspect of the invention relates to use of a compound of formula IA or formula IB in the preparation of a medicament for treating a disease state alleviated by the inhibition of PPP1 R15A and PPP1 R15B.

A further aspect of the invention relates to methods of treating a disease state alleviated by the inhibition of PPP1 R15A and PPP1 R15B in a subject in need thereof, said method comprising administering a therapeutically effective amount of a compound of formula IA or IB.

In one embodiment, the disease state alleviated by the inhibition of PPP1 R15A and

PPP1 R15B is a disorder associated with accumulation of misfolded proteins or proteostatsis disorder.

In a further embodiment, the disease is Huntington's disease, Parkinson's disease, a tauopathy, a protein trafficking disease or a myelin disorder.

In another embodiment, the disease is any polyglutamine disorder.

In a further embodiment, the disease is Distal hereditary motor neuropathy with mutations in the chaperone HSJ1.

A further aspect of the invention relates to pharmaceutical compositions comprising a compound of formula IA or formula IB as described above, admixed with a suitable pharmaceutically acceptable diluent, excipient or carrier.

Brief description of the Figures

Certain embodiments of the present invention will now be described, by way of example only, with reference to the drawings in which:

Figure 1 shows the selective binding of a R15B inhibitor of Example 1 to R15B-PP1 over R15A-PP1.

Figure 2 shows that a selective R15B inhibitor of Example 1 induces a transient

phosphorylation of elF2a in cells in the absence of stress and induces expression of R15A in cells.

Figure 3 shows that a selective R15B inhibitor of Example 1 protects cells from stress.

Figure 4 shows the effects of a selective R15B inhibitor on elF2a phosphorylation following stress. The compound of Example 1 prolongs e\F2 phosphorylation following stress at times where R15A is not yet expressed.

Figure 5 shows the tissue distribution of a compound of Example 1 which exhibits extensive tissue distribution.

Figure 6 shows that the treatment of mice with a compound of Example 1 (10 mg/kg) is not toxic.

Figure 7 shows that the treatment of mice with a compound of Example 1 (10 mg/kg) does not cause the side effects of Guanabenz

Figure 8 shows the induction of R15A in a mammal following treatment with a compound of Example 1.

Figure 9 shows the effectiveness of a R15B inhibitor of Example 1 in preventing disease in a mammal. The example used in Figure 8 is Huntington's disease using the mouse model HD82Gln (Schilling et al., Hum. Mol. Genet., 8, 387-407, 1999). WT: wild-type mice. Tg: HD82Gln.

Figure 10 shows myelin internodes in red (rod shaped) from cultured dorsal root ganglia (DRG) and nuclei in blue (spherical 'blob' shaped) in of the indicated genotype treated with vehicle or compound of Example 1. The myelin internodes in the PMP22-mutant mice are shorter. Treatment with a compound of Example 1 increased the length of myelin internodes in mutant DRG revealing that it improved myelination.

Figure 11 shows blood glucose levels in obese mice db/db animals (n=5 per condition) following treatment with compound of Example 1.

Figure 12 shows protein synthesis rates for a selective R15A inhibitor (1st column -guanabenz (GBZ)), a selective R15B inhibitor (2nd column - compound 16 (TST3)), a combination of GBZ and TST3 (3rd column), and an R15A/B inhibitor (4th column - compound 10). The figure shows that a selective R15A inhibitor doesn't inhibit protein synthesis in unstressed cell. A selective R15B inhibitor transiently inhibits protein synthesis in unstressed cells. Combining an R15A and an R15B inhibitor results in a persistent inhibition of protein synthesis. Likewise, an R15A/B inhibitor persistently inhibits protein synthesis. Y axis shows the relative rates of protein synthesis. X axis shows time following addition of the compounds (10 μΜ), in hours (h).

Figure 13 shows an immunoblot showing that an R15A/B inhibitor (compound 10 at 20μΜ) induces expression of ATF4, confirming the compound is on-target effect. Time after the addition of the compound to cells in culture is shown underneath the ATF4 immunoblot (0, 2, 5, 7.5 h).

Detailed Description of the Invention

In a first aspect, the present invention provides compounds of formula IA:

(IA)

or a pharmaceutically acceptable salt thereof, wherein:

Xa is N or CR2a;

Ya is N or CR4a;

R1a is H, F, CI or Br;

R2a Rsa R4a R5a egch jnc|epenc|entiy represent H, F or CI;

with the proviso that:

when Xa and Ya represent CR2a and CR4a respectively and R2a and R4a are both H:

R1a is not F, CI or Br when R3a and R5a both represent H;

R5a is not F or CI when R1a is CI and R2a is H;

R3a is not F when R1a is CI and R5a is H;

R3a is not CI when R1a and R5a are both H or when R1a is CI and R5a is H;

R1a, R3a and R5a are not all H;

R1a is not CI when R3a is H and R5a is F;

when Xa represents CH and Ya represents CR4a wherein R4a is CI:

R1a and R5a are not both CI;

R3a is not CI when R1a and R5a are CI;

when Xa represents CR2a and Ya represents CR4a and R2a and R4a are both CI, R1a, R3a and R5a are not all H.

In one embodiment, R1a is F, CI or Br.

In another embodiment, R3a is F or CI.

In another embodiment, R5a is H.

In one embodiment, when Xa represents CR2a and Ya represents CR4a, two of R1a, R2a, R3a, R4a and R5a represent CI.

In one embodiment, when Xa represents CR2a and Ya represents CR4a, one of R1a, R2a, R3a, R4a and R5a represents CI and one of R1a, R2a, R3a, R4a and R5a represents F.

In one embodiment, when Xa represents CR2a and Ya represents CR4a, one of R1a, R2a, R3a, R4a and R5a represents CI and one of R1a, R2a, R3a, R4a and R5a represents Br.

In one embodiment, R1a and R3a both represent CI.

In one embodiment, when Xa represents CR2a and Ya represents CR4a, three of R1a, R2a, R3a R4a and R5a represent CI and two of R1a, R2a, R3a, R4a and R5a represent H.

In one embodiment, when Xa represents CR2a and Ya represents CR4a, two of R1a, R2a, R3a, R4a and R5a represent CI, one of R1a, R2a, R3a, R4a and R5a represents F, and two of R1a, R2a, R3a, R4a and R5a represent H.

In one embodiment, when Xa represents CR2a and Ya represents CR4a, two of R1a, R2a, R3a, R4a and R5a represent F, one of R1a, R2a, R3a, R4a and R5a represents CI and two of R1a, R2a, R3a, R4a and R5a represent H.

In one embodiment, three of R1a, R2a, R3a, R4a and R5a represent CI or F and two of R1a, R2a, R3a, R4a and R5a represent H, optionally wherein at least one of R1a, R2a, R3a, R4a and R5a is F.

In one embodiment, when Xa represents CR2a and Ya represents CR4a, R3a is CI or F, two of

R1 a R2a R4a a nd R5a se|ected from p and C| and of R1 a R2a R4a a nd R5a re prese nt

H.

In one embodiment, when Xa represents N, R1a and R3a both represent CI.

In one embodiment,

Xa is CR2a;

Ya is CR4a;

R1a is H, F, CI or Br;

R2a, R3a and R4a each independently represent H, F or CI;

R5a represents H;

with the proviso that:

when Xa and Ya represent CH:

R1a is not F, CI or Br when R3a and R5a both represent H;

R5a is not F or CI when R1a is CI and R2a is H;

R3a is not F when R1a is CI and R5a is H;

R3a is not CI when R1a and R5a are both H or when R1a is CI and R5a is H;

R1a, R3a and R5a are not all H;

R1a is not CI when R3a is H and R5a is F;

when Xa represents CH and Ya represents CR4a wherein R4a is CI:

R1a and R5a are not both CI;

R3a is not CI when R1a and R5a are CI;

when Xa represents CR2a and Ya represents CR4a and R2a and R4a are both CI, R1a, R3a and R5a are not all H.

In one embodiment, the compound of formula IA is in the E-isomer form.

In a second aspect, the present invention provides compounds of formula IB for use in the treatment of a disease state alleviated b the inhibition of PPP1 R15A and PPP1 R15B:

(IB)

or a pharmaceutically acceptable salt thereof, wherein:

Xb is N or CR2b;

Yb is N or CR4b;

R1 b is H, F, CI or Br;

R2b R3b R4b Rsb egch independently represent H, F or CI;

with the proviso that:

when Xb and Yb both represent N, R1a and R3b are not both CI;

R1 b is not Br when Xb is CR2b and R2b is CI;

when R3b and R4b are both H, R1 b and R2b are not both CI;

when Xb is CR2b and R2b and R3b are both H, R1 b is not CI when Yb is CR4b and R4b is F; when Xb is CR2b and Yb is CR4b, R1 b, R2b, R3b, R4b and R5b are not all H;

when Xb is CR2b and Yb is CR4b and R2b, R3b, R4b and R5b are H, R1 b is not CI;

when Xb is CR2b and Yb is CR4b and R2b, R3b and R4b are H, R1 b is not CI when R5b is F; when Xb is CR2b wherein R2b is CI and Yb is CR4b wherein R4b is H, R1 b is not CI when R3b, R4b and R5b are H, or when R3b and R4b are H and R5b is CI.

In one embodiment, Xb represents CR2b and Yb represents CR4b. In an alternative embodiment, Xb and Yb both represent N. In an alternative embodiment, Xb represents N and Yb represents CR4b.

The compounds of formula IB are R15A and R15B inhibitors.

In one embodiment, R1 b represents F, CI or Br.

In another embodiment, R3b represents F or CI.

In another embodiment, R5b is H.

In one embodiment, when Xb represents CR2b and Yb represents CR4b, two of R1 b, R2b, R3b, R4b and R5b represent CI.

In one embodiment, when Xb represents CR2b and Yb represents CR4b, one of R1 b, R2b, R3b, R4b and R5b represents CI and one of R1 b, R2b, R3b, R4b and R5b represents F.

In one embodiment, R1 b and R3b both represent CI.

In one embodiment, when Xb represents CR2b and Yb represents CR4b, three of R1 b, R2b, R2 R4b and R5b represent CI.

In one embodiment, when Xb represents CR2b and Yb represents CR4b, two of R1 b, R2b, R3b,

R4b and R5b represent CI and one of R1 b, R2b, R3b, R4b and R5b represents F.

In one embodiment, when Xb represents CR2b and Yb represents CR4b, two of R1 b, R2b, R3b,

R4b and R5b represent F and one of R1 b, R2b, R3b, R4b and R5b represents CI.

In one embodiment, three of R1a, R2a, R3a, R4a and R5a represent CI or F and two of R1a, R2£

R3a, R4a and R5a represent H, optionally wherein at least one of R1a, R2a, R3a, R4a and R5a is

F.

In one embodiment, when Xb represents N, R1 b and R3b both represent CI.

In one embodiment,

Xb is CR2b;

Yb is CR4b;

R1 b is H, F, CI or Br;

R2b, R3b and R4b each independently represent H, F or CI;

R5b is H;

with the proviso that:

when Xb and Yb both represent N, R1a and R3b are not both CI;

R1 b is not Br when Xb is CR2b and R2b is CI;

when R3b and R4b are both H, R1 b and R2b are not both CI;

when Xb is CR2b and R2b and R3b are both H, R1a is not CI when Yb is CR4b and R4b is F; when Xb is CR2b and Yb is CR4b, R1 b, R2b, R3b, R4b and R5b are not all H;

when Xb is CR2b and Yb is CR4b and R2b, R3b, R4b and R5b are H, R1 b is not CI;

when Xb is CR2b and Yb is CR4b and R2b, R3b and R4b are H, R1 b is not CI when R5b is F; when Xb is CR2b wherein R2b is CI and Yb is CR4b wherein R4b is H, R1 b is not CI when R3b,

R4b and R5b are H, or when R3b and R4b are H and R5b is CI.

In one embodiment, the compound of formula IA is in the E-isomer form.

The term "PPP1 R15A" is used interchangeable with the term "R15A" and the term

"PPP1 R15B" is used interchangeably with the term "R15B". An inhibitor of PPP1 R15A and PPP1 R15B may be referred to as "R15A/B", "R15AB" or "AB" throughout.

Compounds described herein include:

The E isomer forms of the compounds listed above are particularly preferred:

NH

HN NH,

Compound 1 (E)

CI

(E)-2-((4-chlorophenyl)methylene)hydrazine-1- carboximidamide

NH

HN NH,

Compound 2 (E)

CI

(E)-2-((2,4-dichloropyrimidin-5- ethylene)hydrazine-1-carboximidamide

NH

HN NH,

Compound 3 (E)

CI

(E)-2-(3,4,5-trichlorobenzylidene)hydrazine-1- carboximidamide

carboximidamide

Novel compounds of formula IA include:

Compound 2: 2-((2,4-dichloropyrimidin-5-yl)methylene)hydrazine-1 -carboximidamide Compound 3: 2-(3, 4, 5-trichlorobenzylidene)hydrazine-1 -carboximidamide

Compound 4: 2-(2, 4, 5-trichlorobenzylidene)hydrazine-1 -carboximidamide

Compound 5: 2-(3,5-dichloro-4-fluorobenzylidene)hydrazine-1 -carboximidamide Compound 6: 2-(2, 3, 4-trichlorobenzylidene)hydrazine-1 -carboximidamide

Compound 7: 2-(2,4-dichloro-5-fluorobenzylidene)hydrazine-1 -carboximidamide Compound 9: 2-(2-bromo-3-chlorobenzylidene)hydrazine-1 -carboximidamide Compound 13: 2-(2,4-dichloro-3-fluorobenzylidene)hydrazine-1 -carboximidamide Compound 14: 2-(2,3-dichloro-4-fluorobenzylidene)hydrazine-1- carboximidamide Compound 18: 2-(4,5-dichloro-2-fluorobenzylidene)hydrazine-1 -carboximidamide Compound 20: 2-(2-chloro-5-fluorobenzylidene)hydrazine-1 -carboximidamide Comopund 22: 2-((2,6-dichloropyridin-3-yl)methylene)hydrazine-1 -carboximidamide Compound 25: 2-(2-chloro-3-fluorobenzylidene)hydrazine-1 -carboximidamide Compound 27: 2-(2-chloro-3,4-difluorobenzylidene)hydrazine-1 -carboximidamide Compound 29: 2-(2-chloro-3,5-difluorobenzylidene)hydrazine-1 -carboximidamide Compound 32: 2-(2-chloro-4,5-difluorobenzylidene)hydrazine-1-carboximidamide

Novel compounds of formula IA may be selected from the following E isomer forms:

Compound 2(E): (E)-2-((2,4-dichloropyrimidin-5-yl)methylene)hydrazine-1-carboximidamide Compound 3(E): (E)-2-(3,4,5-trichlorobenzylidene)hydrazine-1-carboximidamide

Compound 4(E): (E)-2-(2,4,5-trichlorobenzylidene)hydrazine-1-carboximidamide

Compound 5(E): (E)-2-(3,5-dichloro-4-fluorobenzylidene)hydrazine-1-carboximidamide Compound 6(E): (E)-2-(2,3,4-trichlorobenzylidene)hydrazine-1-carboximidamide

Compound 7(E): (E)-2-(2,4-dichloro-5-fluorobenzylidene)hydrazine-1-carboximidamide Compound 8(E): (E)-2-(4-chloro-3-fluorobenzylidene)hydrazine-1-carboximidamide

Compound 9(E): (E)-2-(2-bromo-3-chlorobenzylidene)hydrazine-1-carboximidamide

Compound 10(E : (E)-2-(2,3,5-trichlorobenzylidene)hydrazine-1-carboximidamide

Compound 1 1 (E : (E)-2-(3,4-dichlorobenzylidene)hydrazine-1-carboximidamide

Compound 13(E : (E)-2-(2,4-dichloro-3-fluorobenzylidene)hydrazine-1-carboximidamide Compound 14(E' : (E)-2-(2,3-dichloro-4-fluorobenzylidene)hydrazine-1- carboximidamide Compound 15(E : (E)-2-(3-chloro-4-fluorobenzylidene)hydrazine-1 -carboximidamide Compound 16(E' : (E)-2-(2,3-dichlorobenzylidene)hydrazine-1 -carboximidamide

Compound 18(E : (E)-2-(4,5-dichloro-2-fluorobenzylidene)hydrazine-1 -carboximidamide Compound 20(E : (E)-2-(2-chloro-5-fluorobenzylidene)hydrazine-1 -carboximidamide Compound 21 (E : (E)-2-((2-chloropyridin-3-yl)methylene)hydrazine-1 -carboximidamide Compound 22(E : (E)-2-((2,6-dichloropyridin-3-yl)methylene)hydrazine-1 -carboximidamide Compound 23(E : (E)-2-(3-fluorobenzylidene)hydrazine-1 -carboximidamide

Compoud 24(E) (E)-2-(3-chlorobenzylidene)hydrazine-1 -carboximidamide

Compound 25(E : (E)-2-(2-chloro-3-fluorobenzylidene)hydrazine-1 -carboximidamide Compound 26(E : (E)-2-(2,5-dichlorobenzylidene)hydrazine-1 -carboximidamide

Compound 27(E : (E)-2-(2-chloro-3,4-difluorobenzylidene)hydrazine-1 -carboximidamide Compound 29(E : (E)-2-(2-chloro-3,5-difluorobenzylidene)hydrazine-1 -carboximidamide Compound 30(E : (E)-2-(3-chloro-2-fluorobenzylidene)hydrazine-1 -carboximidamide Compound 31 (E : (E)-2-(2, 3, 6-trichlorobenzylidene)hydrazine-1 -carboximidamide

Compound 32(E : (E)-2-(2-chloro-4,5-difluorobenzylidene)hydrazine-1 -carboximidamide Comopund 34(E : (E)-2-(3,5-dichlorobenzylidene)hydrazine-1 -carboximidamide

In a preferred embodiment, the compound of formula IA is selected from compound 3, i.e. 2-(3, 4, 5-trichlorobenzylidene)hydrazine-1 -carboximidamide, and compound 4, i.e. 2-(2,4,5-trichlorobenzylidene)hydrazine-1-carboximidamide, in particular the compound of formula IA is selected from (E)-2-(3, 4, 5-trichlorobenzylidene)hydrazine-1 -carboximidamide and (E)-2-(2, 4, 5-trichlorobenzylidene)hydrazine-1 -carboximidamide.

In one embodiment, the compound of formula IA is (E)-2-(3,4,5-trichlorobenzylidene)hydrazine-1-carboximidamide.

I another embodiment, the compound of formula IA is (E)-2-(2,4,5-trichlorobenzylidene)hydrazine-1-carboximidamide.

Compounds of formula IB may be selected from the following:

Compound 1 (E): (E)-2-((4-chlorophenyl)methylene)hydrazine-1-carboximidamide

Compound 3(E): (E)-2-(3,4,5-trichlorobenzylidene)hydrazine-1-carboximidamide

Compound 4(E): (E)-2-(2,4,5-trichlorobenzylidene)hydrazine-1-carboximidamide

Compound 5(E): (E)-2-(3,5-dichloro-4-fluorobenzylidene)hydrazine-1-carboximidamide Compound 6(E): (E)-2-(2,3,4-trichlorobenzylidene)hydrazine-1-carboximidamide

Compound 7(E): (E)-2-(2,4-dichloro-5-fluorobenzylidene)hydrazine-1-carboximidamide Compound 8(E): (E)-2-(4-chloro-3-fluorobenzylidene)hydrazine-1-carboximidamide

Compound 10(E (E)-2-(2,3,5-trichlorobenzylidene)hydrazine-1-carboximidamide

Compound 1 1 (E (E)-2-(3,4-dichlorobenzylidene)hydrazine-1-carboximidamide

Compound 12(E (E)-2-(2,4-dichlorobenzylidene)hydrazine-1-carboximidamide

Compound 13(E (E)-2-(2,4-dichloro-3-fluorobenzylidene)hydrazine-1-carboximidamide Compound 14(E (E)-2-(2,3-dichloro-4-fluorobenzylidene)hydrazine-1- carboximidamide Compound 15(E (E)-2-(3-chloro-4-fluorobenzylidene)hydrazine-1-carboximidamide Compound 17(E' (E)-2-(2-fluorobenzylidene)hydrazine-1 -carboximidamide

Compound 18(E (E)-2-(4,5-dichloro-2-fluorobenzylidene)hydrazine-1 -carboximidamide Compound 21 (E (E)-2-((2-chloropyridin-3-yl)methylene)hydrazine-1 -carboximidamide Compound 22(E (E)-2-((2,6-dichloropyridin-3-yl)methylene)hydrazine-1 -carboximidamide Compound 23(E (E)-2-(3-fluorobenzylidene)hydrazine-1 -carboximidamide

Compound 24(E (E)-2-(3-chlorobenzylidene)hydrazine-1 -carboximidamide

Compound 25(E (E)-2-(2-chloro-3-fluorobenzylidene)hydrazine-1 -carboximidamide Compound 26(E (E)-2-(2,5-dichlorobenzylidene)hydrazine-1 -carboximidamide

Compound 27(E (E)-2-(2-chloro-3,4-difluorobenzylidene)hydrazine-1 -carboximidamide Compound 29(E (E)-2-(2-chloro-3,5-difluorobenzylidene)hydrazine-1 -carboximidamide Compound 30(E (E)-2-(3-chloro-2-fluorobenzylidene)hydrazine-1 -carboximidamide Compound 32(E (E)-2-(2-chloro-4,5-difluorobenzylidene)hydrazine-1 -carboximidamide

In a preferred embodiment, the compound of formula IB is selected from compound 3, i.e. (E)-2-(3,4,5-trichlorobenzylidene)hydrazine-1-carboximidamide, and compound 4, i.e. (E)-2-(2, 4, 5-trichlorobenzylidene)hydrazine-1 -carboximidamide.

In one embodiment, the compound of formula IB is (E)-2-(3,4,5-trichlorobenzylidene)hydrazine-1-carboximidamide.

In another embodiment, the compound of formula IB is (E)-2-(2,4,5-trichlorobenzylidene)hydrazine-1-carboximidamide.

In one embodiment, the compounds of formula IB inhibit PPP1 R15A and PPP1 R15B.

Inhibition of PPP1 R15A and PPP1 R15B can be determined from binding analysis. For example, binding can be analysed using SPR (surface plasmon resonance) to obtain KD values. A PPP1 R15A and PPP1 R15B inhibitor may be defined as a compound where the difference in KD values between R15A and R15B is no more than about 3 fold. In particular, the difference in KD values between R15A and R15B is no more than about 2 fold. For example, the affinity for one target over the other is less than about 3 fold, in particular, less than about 2 fold. A "selective inhibitor" may be defined as a compound where the difference in KD values between R15A and R15B is greater than 3 fold, or even more preferably 10 or 20 fold.

In cells, the compounds of formula IB inhibit protein synthesis. Unlike Guanabenz, an R15A inhibitor which doesn't inhibit protein synthesis in untressed cells (Tsaytler et al., Science, 332, 91-94, 2011), or an R15B inhibitor which transiently inhibits protein synthesis , the combination of an R15A and R15B inhibitor leads to a persistent inhibition of protein synthesis (Figure 12). Likewise, an inhibitor of R15A and R15B (compound 10) persistently inhibits protein synthesis (Figure 12). ATF4 is induced by the inhibitor of R15A and R15B, confirming that the compounds are on-target (Figure 13).

Described herein is the use of compounds of formula (I), or pharmaceutically acceptable salts thereof, as PPP1 R15B selective inhibitors:

(I)

wherein

X is N or CR2;

Y is N or CR4;

R1 , R2, R3 and R4 are independently selected from H, CI or F;

with the proviso that:

when X is CR2 and Y is CR4 the compound of formula I is at least mono-substituted;

when R3 is CI, R2 is not CI;

when both R1 and R4 are CI, R2 is not CI;

when the compound of formula I is di-substituted, X is CR2, Y is CR4 and R1 is CI, R3 is not CI;

when R4 is CI and the compound of formula I is di-substituted, R2 is not CI;

when R1 is F, R2 is not CI;

when X or Y is N and the compound of formula I is mono-substituted, R1 is not CI;

when X is CR2, Y is CR4 and the compound of formula I is mono-substituted, R1 is not F or CI.

The PPP1 R15B selective inhibitor, or a pharmaceutically acceptable salt thereof, may be selected from:

carboximidamide

Salts and Esters

The compounds described herein can be present as salts or esters, in particular pharmaceutically acceptable salts or esters.

Pharmaceutically acceptable salts of the compounds described herein include suitable acid addition or base salts thereof. A review of suitable pharmaceutical salts may be found in Berge et al., J Pharm Sci, 66, 1-19 (1977). Salts which are not pharmaceutically or veterinarily acceptable may still be valuable as intermediates.

Esters are formed either using organic acids or alcohols/hydroxides, depending on the functional group being esterified.

Enantiomers/T automers

In all aspects of the present invention previously discussed, the invention includes, where appropriate all enantiomers, diastereoisomers and tautomers of the compounds of the invention. The person skilled in the art will recognise compounds that possess optical properties (one or more chiral carbon atoms) or tautomeric characteristics. The

corresponding enantiomers and/or tautomers may be isolated/prepared by methods known in the art. Enantiomers are characterised by the absolute configuration of their chiral centres and described by the R- and S-sequencing rules of Cahn, Ingold and Prelog. Such conventions are well known in the art (e.g. see 'Advanced Organic Chemistry', 3rd edition, ed. March, J., John Wiley and Sons, New York, 1985).

Stereo and Geometric Isomers

Some of the compounds of the invention may exist as stereoisomers and/or geometric isomers - e.g. they may possess one or more asymmetric and/or geometric centres and so may exist in two or more stereoisomeric and/or geometric forms. The present invention contemplates the use of all the individual stereoisomers and geometric isomers of those inhibitor agents, and mixtures thereof. The terms used in the claims encompass these forms, provided said forms retain the appropriate functional activity (though not necessarily to the same degree).

The present invention also includes all suitable isotopic variations of the agent or a pharmaceutically acceptable salt thereof. An isotopic variation of an agent of the present invention or a pharmaceutically acceptable salt thereof is defined as one in which at least one atom is replaced by an atom having the same atomic number but an atomic mass different from the atomic mass usually found in nature. Examples of isotopes that can be incorporated into the agent and pharmaceutically acceptable salts thereof include isotopes of hydrogen, carbon, nitrogen, oxygen, phosphorus, sulfur, fluorine and chlorine such as 2H, 3H, 13C, 14C, 15N, 170, 180, 31 P, 32P, 35S, 18F and 36CI, respectively. Certain isotopic variations of the agent and pharmaceutically acceptable salts thereof, for example, those in which a radioactive isotope such as 3H or 14C is incorporated, are useful in drug and/or substrate tissue distribution studies. Tritiated, i.e., 3H, and carbon-14, i.e., 14C, isotopes are

particularly preferred for their ease of preparation and detectability. Further, substitution with isotopes such as deuterium, i.e., 2H, may afford certain therapeutic advantages resulting from greater metabolic stability, for example, increased in vivo half-life or reduced dosage requirements and hence may be preferred in some circumstances. For example, the invention includes compounds of formula I where any hydrogen atom has been replaced by a deuterium atom. Isotopic variations of the agent of the present invention and

pharmaceutically acceptable salts thereof of this invention can generally be prepared by conventional procedures using appropriate isotopic variations of suitable reagents.

Prodrugs

The invention further includes the compounds of the present invention in prodrug form, i.e. covalently bonded compounds which release the active parent drug according to any of the exemplified compounds in vivo. Such prodrugs are generally compounds of the invention wherein one or more appropriate groups have been modified such that the modification may be reversed upon administration to a human or mammalian subject. Reversion is usually performed by an enzyme naturally present in such subject, though it is possible for a second agent to be administered together with such a prodrug in order to perform the reversion in vivo. Examples of such modifications include ester (for example, any of those described above), wherein the reversion may be carried out be an esterase etc. Other such systems will be well known to those skilled in the art.

Solvates

The present invention also includes solvate forms of the compounds of the present invention. The terms used in the claims encompass these forms.

Polymorphs

The invention further relates to the compounds of the present invention in their various crystalline forms, polymorphic forms and (an)hydrous forms. It is well established within the pharmaceutical industry that chemical compounds may be isolated in any of such forms by slightly varying the method of purification and or isolation form the solvents used in the synthetic preparation of such compounds.

THERAPEUTIC APPLICATIONS

The compounds described herein have potential therapeutic applications in treating and preventing various diseases and disorders.

One aspect of the invention relates to compounds of formula IA for use in therapy.

Another aspect of the invention relates to a method of treating a subject having a disorder associated with accumulation of misfolded proteins or perturbation of protein homeostasis, wherein the method comprises administering to the subject a therapeutically effective amount of a compound the invention.

Another aspect of the invention relates to a method of treating a subject having a disease state alleviated by the inhibition of PPP1 R15A and PPP1 R15B, wherein the method comprises administering to the subject a therapeutically effective amount of a compound the invention.

A further aspect of the invention relates a method of preventing a disorder associated with accumulation of misfolded proteins or perturbation of protein homeostasis in a subject, wherein the method comprises administering to the subject a therapeutically effective amount of a compound of the invention.

A further aspect of the invention relates a method of preventing a disease state alleviated by the inhibition of PPP1 R15A and PPP1 R15B in a subject, wherein the method comprises administering to the subject a therapeutically effective amount of a compound of the invention.

Another aspect of the invention relates to compounds of formula IA and formula IB for use in the treatment or prevention of a disorder associated with accumulation of misfolded proteins or perturbation of protein homeostasis.

Another aspect of the invention relates to compounds of formula IA and formula IB for use in the treatment or prevention of a disease state alleviated by the inhibition of PPP1 R15A and PPP1 R15B.

Yet another aspect of the invention relates to use of a compound of formula I A and IB in the manufacture of a medicament for the treatment or prevention of a disorder associated with accumulation of misfolded proteins or perturbation of protein homeostasis.

Yet another aspect of the invention relates to use of a compound of formula I A and IB in the manufacture of a medicament for the treatment or prevention of a disease state alleviated by the inhibition of PPP1 R15A and PPP1 R15B.

PPP1 R15A and PPP1 R15B related diseases are diseases that can be ameliorated by inhibiting PPP1 R15A and PPP1 R15B. These include disorders associated with accumulation of misfolded proteins or perturbation of protein homeostasis (proteostasis) such as

Huntington's disease, Parkinson's disease, Alzheimer's disease, ataxias and other polyglutamine disorders as well as retinal degeneration, glaucoma, amyotrophic lateral sclerosis (ALS) and prion diseases; disorders associated with aggregation of the

microtubule-associated protein tau and include Alzheimer's disease, amyotrophic lateral sclerosis and parkinsonism-dementia complex, argyrophilic grain disease, chronic traumatic encephalopathy, corticobasal degeneration, diffuse neurofibrillary tangles with calcification (DNTC), Down's syndrome, familial British dementia (FBD), familial Danish dementia (FDD), frontotemporal dementia and parkinsonism linked to chromosome 17 (FTDP-17),

frontotemporal lobar degeneration (FTLD), Gerstmann-Straussler-Scheinker disease, Gaudeloupean parkinsonism, myotonic dystrophy, neurodegeneration with brain iron accumulation, Niemann-Pick disease type C, non-Guamanian motor neuron disease with neurofibrillary tangles, Pick's disease, postencephalitic parkinsonism, prion protein cerebral amyloid angiopathy, progressive subcortical gliosis, progressive supranuclear palsy, SLC9A6- related mental retardation, subacute sclerosing panencephalitis, tangle-only dementia, and white matter tauopathy with globular glial includsions; myelin disorders, such as multiple sclerosis, Pelizaeus-Merzbacher disease, vanishing white matter disease, acute disseminated encephalomyelitis, periventricular leukomalacia, periventricular white matter injury, Tabes Dorsalis, Devic's disease, optic neuritis, progressive multifocal

leukoencephalopathy, transverse myelitis, chronic inflammatory demyelinating

polyneuropathy!, anti-MAG peripheral neuropathy, adrenoleukodystrophy,

adrenomyeloneuropathy, diffuse white matter injury, Guillain-Barre Syndrome, central pontine myelinolysis, inherited demyelinating diseases such as leukodystrophy, and Charcot Marie Tooth disease; diseases caused by the misfolding or trafficking defects of any protein made in the endoplasmic reticulum (ER), such as cystic fibrosis, congenital hypothyroid goieter, familial neurohypophyseal diabetes, procollagen biosynthesis disorders including osteogenesis imperfect, hypercholesterolemia, alpha-1 antitrypsin deficiencies, lysomal disorder, retinis pigmentosa (RP), and inflammatory bowel disease; metabolic diseases, such as diabetes, Wolcott-Rallison syndrome, obesity, insulin resistance, hyperlipidemia, fatty liver disease and atherosclerosis; cancer; aging; inflammation; and other disorders including rheumatoid arthritis, type-1 diabetes and vitiligo.

In one preferred embodiment, the compounds described herein are for use in treating disorders associated with pathological UPR or ISR and/or defects in protein homeostasis.

As used herein, the term "method" refers to manners, means, techniques and procedures for accomplishing a given task including, but not limited to, those manners, means, techniques and procedures either known to, or readily developed from known manners, means, techniques and procedures by practitioners of the chemical, pharmacological, biological, biochemical and medical arts.

The term "therapeutically effective amount" refers to that amount of the compound being administered which will relieve to some extent one or more of the symptoms of the disease of disorder being treated.

Herein, the term "treating" includes abrogating, substantially inhibiting, slowing or reversing the progression of a disease or disorder, substantially ameliorating clinical symptoms of a disease or disorder or substantially preventing the appearance of clinical symptoms of a disease or disorder.

The phrase "manufacture of a medicament" includes the above described compound directly as the medicament in addition to its use in a screening programme for further active agents or in any stage of the manufacture of such a medicament.

Diseases with potential protein or peptide misfolding and/or aggregation in their mode of action

Disease-causing proteins are expressed throughout life but degenerative diseases are mostly late-onset. This suggests that the different disease-causing proteins gradually become detrimental over time. While it is now well established that misfolded proteins cause distinct degenerative diseases, why they accumulate remains largely unclear. Cells normally strive to ensure that proteins are correctly folded and indeed all cells have powerful and sophisticated protein quality control systems that very efficiently handle potentially harmful proteins for decades. However, the protein quality control mechanisms seem to gradually fail with age, leading to the accumulation of misfolded proteins with the resulting catastrophic consequences for cells and organisms. These misfolded/aggregated proteins or peptides can be present inside or outside the cell and can be found at any location. In principle, boosting the natural cellular defences against misfolded proteins should represent a generic approach to reduce the pathology in diverse protein misfolding diseases where

misfolded/aggregation prone proteins are present in the pathology. The present invention describes such an approach and demonstrates both its safety and efficacy in a mammal.

Neurodegenerative diseases such as Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD), ataxias and other polyglutamine disorders, tauopathies as well as, retinal degeneration, glaucoma, amyotrophic lateral sclerosis (ALS) and prion diseases are devastating and affect an increasing number of individuals in the ageing population. These diseases are clinically diverse but share a common mechanism. They are caused by the progressive dysfunction and death of specific nerve cells in selective regions of the brain due to the accumulation of specific proteins of aberrant shape. The misfolded and

aggregation prone proteins include, but are not restricted to: Αβ42, α-synuclein, TAU, TDP-43, TLS/FUS, SOD1 , Huntingtin and other proteins with polyglutamine expansion, prions and the translation product(s) of C90RF72.

The Applicant has demonstrated that the compound of Example 1 selectively inhibits PPP1 R15B-PP1 , correcting a protein misfolding disease in mice. Inhibitors of PPP1 R15B described herein therefore have therapeutic applications in the treatment of a variety of diseases where a misfolded protein is involved and in particular with an accumulation of misfolded proteins. Inhibitors of PPP1 R15A and PPP1 R15B, such as the compounds of formula IB, are also expected to have application in the treatment of diseases where a misfolded protein is involved.

The present invention provides for the therapy of polyglutamine disorders.

Huntington's disease belongs to a broader group of disorders, "polyglutamine disorders", characterized by expansion of CAG codons translated in glutamine in unrelated proteins. Huntington's disease is caused by an expansion in the gene encoding Huntingtin; Spinal and bulbar muscular atrophy, Dentalorubral-pallidoluysian atrophy, and Spinocerebellar ataxias are caused by expansion in genes encoding Androgen Receptor, Atrophin 1 , Ataxin 1 , 2, 3, a-voltage dependent calcium channel subunit and TBP respectively. CAG expansion is translated in polyglutamine and causes aggregation of the affected protein. Accordingly, prevention and/or treatment of polyglutamine disorders such as these are within the scope of the invention.

As an example, the Applicant has shown that the compound of Example 1 ameliorates Huntington's disease in a mammal. Thus, without wishing to be bound by theory, it is believed that an inhibitor of PPP1 R15B has a protective effect against diverse diseases caused by misfolded/aggregated proteins such as but not restricted to Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD), ataxias and other polyglutamine disorders as well as, retinal degeneration, glaucoma, Amyotrophic Lateral Sclerosis (ALS), tauopathies and prion diseases. Inhibitors of PPP1 R15A and PPP1 R15B, such as the compounds of formula IB, are expected to have the same effect.

The diseases include any diseases where misfolding/aggregation is involved with the proteins known today and described above but will also apply to new proteins and perhaps new diseases in the future.

In a preferred embodiment, the invention provides for the therapy of proteostasis diseases.

In another embodiment, the compounds described herein are for use in treating a disease where accumulation of misfolded proteins is involved in the mode of action.

In a further embodiment, the disease or disorder is Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD), ataxias or other polyglutamine disorder, retinal degeneration, glaucoma, Amyotrophic Lateral Sclerosis (ALS), tauopathies or a prion disease.

In a particular embodiment, the compounds described herein are for use in the treatment of Huntington's disease.

In another particular embodiment, the compounds described herein are for use in the treatment of Parkinson's disease.

In one embodiment, the disease or disorder is associated with aggregation of the

microtubule-associated protein tau.

The Applicant has demonstrated that the compound of Example 1 selectively inhibits

PPP1 R15B-PP1 , correcting a protein misfolding disease in mice. PPP1 R15B inhibitors can also be useful to prevent or stop the progression of diseases that are caused by the same mechanism: accumulation of misfolded proteins. Inhibitors of PPP1 R15A and PPP1 R15B, such as the compounds of formula IB, are also expected to have this application.

Examples of such diseases include, Alzheimer's disease, amyotrophic lateral sclerosis and, parkinsonism and dementia, argyrophilic grain disease, chronic traumatic encephalopathy, corticobasal degeneration, diffuse neurofibrillary tangles with calcification (DNTC), Down's syndrome, familial British dementia (FBD), familial Danish dementia (FDD), frontotemporal dementia and parkinsonism linked to chromosome 17 (FTDP-17) (caused by MAPT mutations), frontotemporal lobar degeneration (FTLD) (some cases caused by C90RF72 mutations), Gerstmann-Straussler-Scheinker disease, Gaudeloupean parkinsonism, myotonic dystrophy, neurodegeneration with brain iron accumulation, Niemann-Pick disease, type C, non-Guamanian motor neuron disease with neurofibrillary tangles, Pick's disease, postencephalitic parkinsonism, prion protein cerebral amyloid angiopathy, progressive subcortical gliosis, progressive supranuclear palsy, SLC9A6-related mental retardation, subacute sclerosing panencephalitis, tangle-only dementia, white matter tauopathy with globular glial inclusions.

In one embodiment, the disease is a myelin disorder.

Myelin is an abundant protein of both the central and peripheral nervous system. It is produced by two cell types: oligodendrocytes in the central nervous system and Schwann cells in the peripheral nervous system. Myelin forms a sheath around axons to insure the speed of conduction of electrical impulses along an axon, and to prevent electrical current from dissipating from the axon. Myelin function is essential for the nervous system.

Myelin disorders affect more than 2.5 million people worldwide and are defined as any disease associated with damage in myelin. Myelin disorders are manifested by diverse symptoms including but not restricted to motor impairments, sensory impairments, cognitive dysfunction, emotional disturbances, and impaired coordination.

There are many demyelinating disorders, the most common of which is multiple sclerosis (MS). Multiple sclerosis is an autoimmune disease affecting the brain and spinal cord resulting in demyelination in the brain. In addition to MS, other demyelinating disorders include but are not limited to Pelizaeus-Merzbacher disease and vanishing white matter disease, acute disseminated encephalomyelitis, periventricular leukomalacia,

periventricular white matter injury, Tabes Dorsalis, Devic's disease, optic neuritis, progressive multifocal leukoencephalopathy, transverse myelitis, chronic inflammatory demyelinating polyneuropathy, anti-MAG peripheral neuropathy, adrenoleukodystrophy, adrenomyeloneuropathy, diffuse white matter injury, Guillain-Barre Syndrome, central pontine myelinolysis, inherited demyelinating diseases such as leukodystrophy, and Charcot Marie Tooth (CMT) disease.

CMT disease is a group of myelin neuropathies caused by mutations in a number of genes. Mutations in the peripheral myelin protein PMP22 are the most common causes of CMT. A mutation in PMP22 (Trembler-J) causes the misfolding of PMP22 and results in a disease in mice that resembles CMT in human due to defects in myelin in the peripheral nervous system. The Applicants have demonstrated that the compound of Example 1 can improve myelination in explants from neuropathic mice. The Applicants have demonstrated that improving myelination in explants from neuropathic mice predicts efficacy in a mammal (Das et al. Science, 2015). Therefore the compound of Example 1 will be useful in treating CMT in mammals and other myelin disorders where it is known that the mechanisms are similar and involve the elF2a pathway (Lin and Popko, Nat. Neurosci., 72, 379-385, 2009) and is anticipated that inhibitors of PPP1 R15A and PPP1 R15B, such as the compounds of formula (I), will also be useful in treating CMT.

In one embodiment, the compounds described herein are for use in treating a myelin disorder.

In another embodiment, the compounds described herein are for use in treating Charcot Marie Tooth disease.

In a further embodiment, the compounds described herein are for use in treating myelin disorders of the central nervous system, for example, multiple sclerosis. It is known that the mechanisms of CMT and MS are similar with an exhaustion of myelin producing cells (Schwann cells in CMT and oligodendrecytes in MS) and involve pathological signalling of the elF2a-RRR1 R15A pathway (Lin and Popko, Nat. Neurosci., 72, 379-385, 2009). Since the Applicants have demonstrated that Example 1 is effective in a myelinopathy and have also demonstrated the bioavailability of a compound of Example 1 in both the central and peripheral nervous system (Figure 5), it is anticipated that PPP1 R15B inhibitors, and inhibitors of PPP1 R15A and PPP1 R15B such as the compounds of formula IB, will be useful in treating multiple sclerosis.

In one embodiment, the disease is a disease arising as a consequence of a mutation in a protein resulting in its misfolding and mislocalisation or trafficking defects.

The Applicants have demonstrated that the compound of Example 1 can rescue defects caused by one misfolded protein, PMP22, synthetized in the endoplasmic reticulum (ER). Due to the mechanism of action (decreasing translation to increase folding) an inhibitor of PPP1 R15B, and an inhibitor of PPP1 R15A and PPP1 R15B, will also be useful for the treatment of diseases due to the misfolding or trafficking defects of any protein made in the ER, including transmembrane or secreted proteins.

Examples of such diseases include: cystic fibrosis caused by mutations impairing folding of the transmembrane protein (CFTR); congenital hypothyroid goitre with thyroglobulin deficiency due to the misfolding and/or trafficking defect of the hormone thyroglobulin;

familial neurohypophyseal diabetes insipidus caused by misfolding and absence of circulating arginine vasopressin (this may also include certain forms of genetically inherited nephrogenic diabetes insipidus); procollagen biosynthesis disorders where the disease is caused by a failure to fold, assemble and synthetize collagen, such as, but not restricted to, osteogenesis imperfect; more generally, any genetic diseases of connective tissues where protein misfolding/ lack of synthesis or mislocalization is in the mode of action such as growth plate dysplasia associated with defects of proteins from extracellular matrix;

hypercholesterolemia, with molecular defects caused by mutations in the LDL receptor causing lack of synthesis, altered intracellular transport, or abnormal function; Alpha-1 antitrypsin deficiencies due to the misfolding of alpha 1 antitrypsin; lysomal disorder due to misfolding of proteins associated for lysosomal function such as Gaucher disease and Niemann-Pick disease and Anderson-Fabry disease; retinis pigmentosa (RP), which is the most common form of hereditary retinal degeneration caused by the misfolding of rhodopsin proteins, their ER retention and the resulting ER stress and cell death; and inflammatory bowel disease which is associated with ER stress.

For the same reasons, an inhibitor of PPP1 R15B or an inhibitor of PPP1 R15A and

PPP1 R15B, such as the compounds of formula IB, can be used to treat the following disorders, associated with pathological UPR and/or defects in a transmembrane protein (Lin and Popko, Nat. Neurosci., 72, 379-385, 2009). These disorders include, but are not restricted to Pelizaeus-Merzbacher disease associated with mutations in the membrane proteolipid protein (PLP) gene, and vanishing white matter (VWM) disease as well as multiple sclerosis, a common myelin disorder.

In one embodiment, the compounds described herein are for use in the treatment of diseases arising from a mutation in a protein resulting in the protein's misfolding and mislocalisation or trafficking defects.

In a another embodiment, the disease arising from a mutation in a protein resulting in the protein's misfolding and mislocalisation or trafficking defects is selected from cystic fibrosis, congenital hypothyroid goitre, familial neurohypophyseal diabetes insipidus, procollagen biosynthesis disorders such as osteogenesis, hypercholesterolemia, alpha-1 antitrypsin deficiencies, lysomal disorders such as Gaucher disease, Niemann-Pick disease and Anderson-Fabry disease, retinis pigmentosa and inflammatory bowel disease.

In one embodiment, the disease is a metabolic disease.

It is known that metabolic diseases such as diabetes, obesity, insulin resistance, hyperlipidemia, fatty liver disease, and atherosclerosis are associated with pathological ER stress and it is believed that pharmacological modulators of the UPR may have therapeutic benefit (Cao and Kaufman, 2012, Curr Biol, vol. 22 (16)). However, as no PPP1 R15B

inhibitors were previously available and PPP1 R15B inhibition was predicted to be

deleterious, and furthermore, since it is challenging to inhibit phosphatases, it was unclear whether PPP1 R15B could be a therapeutic target in metabolic diseases.

The inventors have demonstrated that the compound of Example 1 can ameliorate a metabolic disorder in a mammal (Figure 1 1). Therefore, PPP1 R15B inhibitors will be useful to treat metabolic disorders such as, but not restricted to diabetes, obesity, fatty liver disease, and atherosclerosis. It is also expected that inhibitors of PPP1 R15A and

PPP1 R15B, such as the compounds of formula (I), will also be useful in treating metabolic disorders.

In one embodiment, the compounds described herein are for use in the treatment of metabolic disorders.

In a preferred embodiment, the metabolic disorder is selected from diabetes, obesity, fatty liver disease, and atherosclerosis.

PPP1 R15B selective inhibitors are also useful in the treatment of other disorders including rheumatoid arthritis, diabetes, Wolkott Rallison syndrome, inflammatory bowel disease and vitiligo, which involve UPR in their mechanism of action (Cao and Kaufman, 2012, Curr Biol, vol. 22 (16)). PPP1 R15A and PPP1 R15B inhibitors, such as the compounds of formula (I) are also expected to be useful in treatment of these disorders.

Cancer

In one embodiment, a compound described herein is for use in treating cancer.

Cancer cells have high metabolic requirement and their proliferation relies on efficient protein synthesis. Translation initiation plays a crucial role in controlling protein homeostasis, differentiation, proliferation and malignant transformation. Increasing translation initiation contributes to cancer initiation and conversely, decreasing translation initiation could reduce tumor growth (Donze et al., 1995, EM BO J, 14, 3828- 34; Pervin et al., 2008, Cancer Res, 68, 4862-74; Chen et al., 2011 , Nat Chem Biol, 7, 610-6). Without wishing to be bound by theory, it is believed that inhibiting PPP1 R15A and PPP1 R15B could reduce translation in tumor cells and thus reduce tumor growth.

Aging

There is abundant literature showing that reducing protein synthesis increases life span (Tavernarakis, 2008, Trends Cell Biol, 18(5), 228-235. Therefore it is reasonable to predict that reducing protein synthesis by inhibiting PPP1 R15A and PPP1 R15B will increase lifespan.

Inflammation

Salubrinal is an inducer of elF2a phosphorylation and is thought to inhibit R15A and R15B phosphatases by an unknown mechanism. Salubrinal was found to suppress inflammation (Hamamura et al., 2015, Cellular Signalling, 27(4), 828-835). However, Salubrinal cannot be used in human due to toxicity issues. It is reasonable to anticipate that the R15A/B inhibitors disclosed here will be a potential therapy for diseases involving inflammation.

A non exhaustive set of examples of diseases associated with inflammation are: arthritis, ulcerative colitis and inflammatory bowel disease, infections associated with inflammation, fibrosis, neurodegenerative diseases associated with inflammation or broadly any human diseases associated with inflammation.

In particular, diseases associated with inflammation include: rheumatoid arthritis; multiple sclerosis; inflammatory bowel disease (IBD), which is a term mainly used to describe two conditions, ulcerative colitis and Crohn's disease; diabetes; lupus nephritis; autoimmune inner ear disease (AIED); cystic fibrosis; Graves disease; myocarditis; autoimmune hepatitis; Alzheimer's disease; Parkinson's disease; scleroderma; Gall Bladder Disease; Hashimoto's Thyroiditis; autoimmune reaction originating in the gut triggered by antibodies against thyroid enzymes and proteins; Guillain-Barre autoimmune attack of the nervous system often triggered by autoimmune response to external stressors such as vaccinations; Polymyalgia Rheumatica; leukemia; and asthma.

Anit-Viral Agents

The compounds described herein may be used as anti-viral agents. Protein synthesis is required for viral replication. Having shown that AB inhibitors inhibit protein synthesis, it is reasonable to anticipate that they will block viral replication and be useful to prevent infectious disease in human. Indeed, by way of example, it has been previously shown that salubrinal, an inducer of elF2a phosphorylation blocks the replication of Herpex simplex virus (Boyce, M., et al. (2005) Science 307(571 1), 935-939). However, Salubrinal cannot be used in human due to toxicity issues. Therefore, the R15A/B inhibitors disclosed herein may have a therapeutic advantage over other translation inhibitors.

The Applicants have shown that a PPP1 R15B inhibitor can prevent Huntington's disease. PPP1 R15B is constitutively expressed and is therefore a more broadly applicable disease target. It is reasonable to anticipate that AB inhibitors administered at a dose such that targets are only inhibited by short pulses will prevent most (if not all) protein misfolding diseases.

PHARMACEUTICAL COMPOSITIONS

According to a further aspect of the invention there is provided a pharmaceutical composition comprising a compound described herein for use in therapy combined with any

pharmaceutically acceptable carrier, adjuvant or vehicle.

The term "pharmaceutical composition" in the context of this invention means a composition comprising an active agent and additionally one or more pharmaceutically acceptable excipients.

Suitable pharmaceutically acceptable excipients are known to those skilled in the art and generally include an acceptable composition, material, carrier, diluent or vehicle suitable for administering a compound of the invention to an animal.

In one embodiment the animal is a mammal. In another embodiment the mammal is human.

Pharmaceutical formulations include those suitable for oral, topical (including dermal, buccal, ocular and sublingual) rectal or parenteral (including subcutaneous, intradermal,

intramuscular and intravenous), nasal, intra-ocularly and pulmonary administration e.g., by inhalation. The formulation may, where appropriate, be conveniently presented in discrete dosage units and may be prepared by any of the methods well known in the art of pharmacy.

Dosages may be varied depending on the requirements of the patient, the severity of the condition being treated and the characteristics of the active ingredient being employed.

Determination of the effective dose is within the remit of the skilled person, without undue burden. Suitable dosage forms for administration to mammals, including humans are typically in the range of up to 100mg/kg body weight, or may be 0.1 mg/kg, 10mg/kg,

20mg/kg, 30mg/kg for example.

According to a further aspect of the invention, there is provided a process for the preparation of a pharmaceutical composition as described above, the process comprising bringing the active compound(s) into association with the carrier, for example by admixture.

In general, the formulations are prepared by uniformly and intimately bringing into association the active agent with liquid carriers or finely divided solid carriers or both, and then if necessary shaping the product. The invention extends to methods for preparing a pharmaceutical composition comprising bringing a compound disclosed herein in conjunction or association with a pharmaceutically acceptable carrier or vehicle. All methods include the step of bringing into association an active compound with liquid carriers or finely divided solid carriers or both and then, if necessary, shaping the product into the desired

formulation.

COMBINATIONS

In a particularly preferred embodiment, the one or more compounds of the invention are administered in combination with one or more other active agents, for example, existing drugs available on the market. In such cases, the inhibitors of the invention may be administered consecutively, simultaneously or sequentially with the one or more other active agents.

Combining a compound which is a R15A inhibitor with a compound which is a R15B inhibitor results in the same advantageous properties as a compound which inhibitors both R15A and R15B. Therefore, one aspect of the present invention provides a combination of a R15A inhibitor compound and a R15B inhibitor compound. The combination is useful in the treatment of a disease state alleviated by the inhibition of PPP1 R15A and PPP1 R15B, for example, a disorder associated with accumulation of misfolded proteins or proteostatsis disorder. The combination may be guanabenz, a known R15A inhibitor, and (E)-2-(2,3-dichlorobenzylidene)hydrazine-1-carboximidamide (compound 16), a R15B inhibitor.

Drugs in general are more effective when used in combination. In particular, combination therapy is desirable in order to avoid an overlap of major toxicities, mechanism of action and resistance mechanism(s). Furthermore, it is also desirable to administer most drugs at their maximum tolerated doses with minimum time intervals between such doses. The major advantages of combining drugs are that it may promote additive or possible synergistic effects through biochemical interactions and also may decrease the emergence of resistance.

Beneficial combinations may be suggested by studying the inhibitory activity of the test inhibitors with agents known or suspected of being valuable in the treatment of a particular disorder. This procedure can also be used to determine the order of administration of the agents, i.e. before, simultaneously, or after delivery. Such scheduling may be a feature of all the active agents identified herein.

EXAMPLES

Preparation of the compounds according to the present invention

The compounds according to the present invention can be prepared according to the following procedures, which are shown in respect of the E isomeric forms. From these methods it will be known to the skilled person how other isomeric forms, or the racemate, could be obtained.

Compound 1 - (E)-2-((4-chlorophenyl)methylene)hydrazine-1 -carboximidamide

CLAIMS

1. A compound of formula IA:

(IA)

or a pharmaceutically acceptable salt thereof, wherein:

Xa is N or CR2a;

Ya is N or CR4a;

R1a is H, F, CI or Br;

R2a Rsa R4a R5a egch jnc|epenc|entiy represent H, F or CI;

with the proviso that:

when Xa and Ya represent CH:

R1a is not F, CI or Br when R3a and R5a both represent H;

R5a is not F or CI when R1a is CI and R2a is H;

R3a is not F when R1a is CI and R5a is H;

R3a is not CI when R1a and R5a are both H or when R1a is CI and R5a is H;

R1a, R3a and R5a are not all H; or

R1a is not CI when R3a is H and R5a is F;

when Xa represents CH and Ya represents CR4a wherein R4a is CI:

R1a and R5a are not both CI;

R3a is not CI when R1a and R5a are CI;

when Xa represents CR2a and Ya represents CR4a and R2a and R4a are both CI, R1a, R3a and R5a are not all H.

2. The compound according to claim 1 , wherein Xa represents CR2a and Ya represents CR' wherein R2a and R4a each independently represent H, F or CI.

3. The compound according to claim 1 or claim 2, wherein three of R1a, R2a, R3a, R4a and R: represent CI or F and two of R1a, R2a, R3a, R4a and R5a represent H, optionally wherein at least one of R1a, R2a, R3a, R4a and R5a is F.

4. The compound according to claim 1 or claim 2, wherein three of R1a, R2a, R3a, R4a and R: represent CI and two of R1a, R2a, R3a, R4a and R5a represent H.

5. The compound according to claim 1 or claim 2, wherein R3a is CI or F, and R1a, R2a, R4a and R5a are independently selected from H, F and CI, wherein two of R1a, R2a, R4a and R5a are selected from F and CI and two of R1a, R2a, R4a and R5a represent H.

6. The compound according to any preceding claim, wherein R5a represents H.

7. The compound according to any preceding claim, wherein the compound is in the E-isomer form.

8. The compound according to claim 1 , wherein the compound is selected from

(E)-2-((2,4-dichloropyrimidin-5-yl)methylene)hydrazine-1-carboximidamide

(E)-2-(3,4,5-trichlorobenzylidene)hydrazine-1-carboximidamide

(E)-2-(2,4,5-trichlorobenzylidene)hydrazine-1-carboximidamide

(E)-2-(3,5-dichloro-4-fluorobenzylidene)hydrazine-1-carboximidamide

(E)-2-(2,3,4-trichlorobenzylidene)hydrazine-1-carboximidamide

(E)-2-(2,4-dichloro-5-fluorobenzylidene)hydrazine-1-carboximidamide

(E)-2-(4-chloro-3-fluorobenzylidene)hydrazine-1-carboximidamide

(E)-2-(2-bromo-3-chlorobenzylidene)hydrazine-1-carboximidamide

(E)-2-(2,3,5-trichlorobenzylidene)hydrazine-1-carboximidamide

(E)-2-(3,4-dichlorobenzylidene)hydrazine-1-carboximidamide

(E)-2-(2,4-dichloro-3-fluorobenzylidene)hydrazine-1-carboximidamide

(E)-2-(2,3-dichloro-4-fluorobenzylidene)hydrazine-1- carboximidamide

(E)-2-(3-chloro-4-fluorobenzylidene)hydrazine-1-carboximidamide

(E)-2-(2,3-dichlorobenzylidene)hydrazine-1 -carboximidamide

(E)-2-(4,5-dichloro-2-fluorobenzylidene)hydrazine-1 -carboximidamide

(E)-2-(2-chloro-5-fluorobenzylidene)hydrazine-1 -carboximidamide

(E)-2-((2-chloropyridin-3-yl)methylene)hydrazine-1-carboximidamide

(E)-2-((2,6-dichloropyridin-3-yl)methylene)hydrazine-1 -carboximidamide

(E)-2-(3-fluorobenzylidene)hydrazine-1 -carboximidamide

(E)-2-(3-chlorobenzylidene)hydrazine-1 -carboximidamide

(E)-2-(2-chloro-3-fluorobenzylidene)hydrazine-1-carboxirnidarnide

(E)-2-(2,5-dichlorobenzylidene)hydrazine-1-carboximidamide

(E)-2-(2-chloro-3,4-difluorobenzylidene)hydrazine-1-carboximidamide

(E)-2-(2-chloro-3,5-difluorobenzylidene)hydrazine-1-carboximidamide

(E)-2-(3-chloro-2-fluorobenzylidene)hydrazine-1-carboximidamide

(E)-2-(2,3,6-trichlorobenzylidene)hydrazine-1-carboximidamide

(E)-2-(2-chloro-4,5-difluorobenzylidene)hydrazine-1-carboxirnidamide

(E)-2-(3,5-dichlorobenzylidene)hydrazine-1-carboximidamide

or a pharmaceutically acceptable salt thereof.

9. A compound of formula IB for use the treatment of a disease state alleviated by the inhibition of PPP1 R15A and PPP1 R15B,

(IB)

or a pharmaceutically acceptable salt thereof, wherein:

Xb is N or CR2b;

Yb is N or CR4b;

R1 b is H, F, CI or Br;

R2b R3b R4b Rsb egch independently represent H, F or CI;

with the proviso that:

when Xb and Yb both represent N, R1 b and R3b are not both CI;

R1 b is not Br when Xb is CR2b and R2b is CI;

when R3b and R4b are both H, R1 b and R2b are not both CI;

when Xb is CR2b and R2b and R3b are both H, R1 b is not CI when Yb is CR4b and R4b when Xb is CR2b and Yb is CR4b, R1 b, R2b, R3b, R4b and R5b are not all H;

when Xb is CR2b and Yb is CR4b and R2b, R3b, R4b and R5b are H, R1 b is not CI;

when Xb is CR2b and Yb is CR4b and R2b, R3b and R4b are H, R1 b is not CI when R5b i when Xb is CR2b wherein R2b is CI and Yb is CR4b wherein R4b is H, R1 b is not CI when R3b, R4b and R5b are H, or when R3b and R4b are H and R5b is CI.

10. The compound for use according to claim 9, wherein Xb represents CR2b and Yb represents CR4b, wherein R2b and R4b each independently represent H, F or CI.

1 1. The compound for use according to claim 9 or claim 10, wherein three of R1 b, R2b, R3b, R4b and R5b represent CI or F and two of R1 b, R2b, R3b, R4b and R5b represent H, optionally wherein at least one of R1 b, R2b, R3b, R4b and R5b represents F.

12. The compound for use according to claim 9 or claim 10, wherein three of R1 b, R2b, R3b, R4b and R5b represent CI and two of R1 b, R2b, R3b, R4b and R5b represent H.

13. The compound for use according to claim 9 or claim 10, wherein R3b is CI or F and R1 b, R2b, R4b and R5b are independently selected from H, F and CI, wherein two of R1 b, R2b, R4b and R5b are selected from F and CI and two of R1 b, R2b, R4b and R5b is H.

14. The compound for use according to any one of claims 9 to 13, wherein R5b is H.

15. The compound for use according to any one of claims 9 to 14, wherein the compound is in the E-isomer form.

16. The compound for use according to claim 9, wherein the compound is selected from: (E)-2-((4-chlorophenyl)methylene)hydrazine-1-carboximidamide

(E)-2-(3,4,5-trichlorobenzylidene)hydrazine-1-carboximidamide

(E)-2-(2,4,5-trichlorobenzylidene)hydrazine-1-carboximidamide

(E)-2-(3,5-dichloro-4-fluorobenzylidene)hydrazine-1-carboximidamide

(E)-2-(2,3,4-trichlorobenzylidene)hydrazine-1-carboximidamide

(E)-2-(2,4-dichloro-5-fluorobenzylidene)hydrazine-1-carboximidamide

(E)-2-(4-chloro-3-fluorobenzylidene)hydrazine-1-carboximidamide

(E)-2-(2,3,5-trichlorobenzylidene)hydrazine-1-carboximidamide

(E)-2-(3,4-dichlorobenzylidene)hydrazine-1-carboximidamide

(E)-2-(2,4-dichlorobenzylidene)hydrazine-1-carboximidamide

(E)-2-(2,4-dichloro-3-fluorobenzylidene)hydrazine-1-carboximidamide

(E)-2-(2,3-dichloro-4-fluorobenzylidene)hydrazine-1- carboximidamide

(E)-2-(3-chloro-4-fluorobenzylidene)hydrazine-1-carboximidamide

(E)-2-(2-fluorobenzylidene)hydrazine-1 -carboximidamide

(E)-2-(4,5-dichloro-2-fluorobenzylidene)hydrazine-1-carboximidarnide

(E)-2-((2-chloropyridin-3-yl)methylene)hydrazine-1-carboximidarnide

(E)-2-((2,6-dichloropyridin-3-yl)methylene)hydrazine-1-carboximidamide

(E)-2-(3-fluorobenzylidene)hydrazine-1-carboximidamide

(E)-2-(3-chlorobenzylidene)hydrazine-1-carboximidamide

(E)-2-(2-chloro-3-fluorobenzylidene)hydrazine-1-carboximidamide

(E)-2-(2,5-dichlorobenzylidene)hydrazine-1-carboximidamide

(E)-2-(2-chloro-3,4-difluorobenzylidene)hydrazine-1-carboxirnidarnide

(E)-2-(2-chloro-3,5-difluorobenzylidene)hydrazine-1-carboxirnidarnide

(E)-2-(3-chloro-2-fluorobenzylidene)hydrazine-1-carboximidamide

(E)-2-(2-chloro-4,5-difluorobenzylidene)hydrazine-1-carboxirnidarnide

or a pharmaceutically acceptable salt thereof.

17. The compound according to claim 1 or compound for use according to claim 9, which is (E)-2-(3,4,5-trichlorobenzylidene)hydrazine-1-carboximidamide or a pharmaceutically acceptable salt thereof.

18. The compound according to claim 1 or compound for use according to claim 9, which is (E)-2-(2,4,5-trichlorobenzylidene)hydrazine-1-carboximidamide or a pharmaceutically acceptable salt thereof.

19. A compound as defined in any one of claims 1 to 8, 17 or 18, for use in the treatment of a disorder associated with accumulation of misfolded proteins or a proteostatsis disorder.

20. The compound for use according to claim 19, wherein the disorder is associated with PPP1 R15A and PPP1 R15B.

21. The compound for use according to any one of claims 9 to 18, wherein the disorder is a disorder associated with accumulation of misfolded proteins or a proteostatsis disorder.

22. The compound for use according to any one of claims 19 to 21 , wherein the disorder is selected from Alzheimer's disease, Parkinson's disease, Huntington's disease, other polyglutamine disorders and tauopathies.

23. A pharmaceutical composition comprising a compound as defined in any one of claims 1 to 9, 17 or 18, in combination with a pharmaceutically acceptable excipient.

24. Use of a compound of formula IA as defined in any one of claims 1 to 8, 17 or 18 in the preparation of a medicament for treating a disorder associated with accumulation of misfolded proteins or a proteostatsis disorder.

25. A method of treating a disorder associated with accumulation of misfolded proteins or a proteostatsis disorder in a subject in need thereof, said method comprising administering a therapeutically effective amount of a compound of formula IA as defined in any one of claims 1 to 8, 17 or 18.