Pacritinib

Pacritinib

A Jak2 inhibitor potentially for the treatment of acute myeloid Leukemia and myelofibrosis.

ONX-0803; SB-1518
CAS No. 937272-79-2

472.57868 g/mol, C₂₈H₃₂N₄O₃

S*Bio Pte Ltd. and concert innovator

11-(2-pyrrolidin-1-ylethoxy)-14,19-dioxa-5,7,26-triazatetracyclo(19.3.1.1(2,6).1(8,12))heptacosa-1(25),2(26),3,5,8,10,12(27),16,21,23-decaene

• (16E)-11-[2-(1-Pyrrolidinyl)ethoxy]-14,19-Dioxa-5,7,27-triazatetracyclo[19.3.1.12,6.18,12]heptacosa-1(25),2,4,6(27),8,10,12(26),16,21,23-decaene
• 11-(2-pyrrolidin-1-yl-ethoxy)-14,19-dioxa-5,7,26-triaza-tetracyclo[19.3.1.1(2,6).1(8,12)]heptacosa-1(25),2(26),3,5,8,10,12(27),16,21,23-decaene
• SB-1518|||(16E)-11-[2-(1-Pyrrolidinyl)ethoxy]-14,19-dioxa-5,7,27-triazatetracyclo[19.3.1.12,6.18,12]heptacosa-1(25),2,4,6(27),8,10,12(26),16,21,23-decaene

Pacritinib (INN^[1]) is a macrocyclic Janus kinase inhibitor that is being developed for the treatment of myelofibrosis. It mainly inhibits Janus kinase 2 (JAK2). The drug is in Phase III clinical trials as of 2013.^[2] The drug was discovered in Singapore at the labs of S*BIO Pte Ltd. It is a potent JAK2 inhibitor with activity of IC₅₀ = 23 nM for the JAK2WT variant and 19 nM for JAK2V617F with very good selectivity against JAK1 and JAK3 (IC₅₀ = 1280 and 520 nM, respectively).^[3][4] The drug is acquired by Cell Therapeutics, Inc. (CTI) and Baxter international and could effectively address an unmet medical need for patients living with myelofibrosis who face treatment-emergent thrombocytopenia on marketed JAK inhibitors.^[5]

Pacritinib is an orally bioavailable inhibitor of Janus kinase 2 (JAK2) and the JAK2 mutant JAK2V617F with potential antineoplastic activity. Oral JAK2 inhibitor SB1518 competes with JAK2 for ATP binding, which may result in inhibition of JAK2 activation, inhibition of the JAK-STAT signaling pathway, and so caspase-dependent apoptosis. JAK2 is the most common mutated gene in bcr-abl-negative myeloproliferative disorders; the JAK2V617F gain-of-function mutation involves a valine-to-phenylalanine modification at position 617. The JAK-STAT signaling pathway is a major mediator of cytokine activity.

Pacritinib is an orally bioavailable inhibitor of Janus kinase 2 (JAK2) and the JAK2 mutant JAK2V617F with potential antineoplastic activity. Oral JAK2 inhibitor SB1518 competes with JAK2 for ATP binding, which may result in inhibition of JAK2 activation, inhibition of the JAK-STAT signaling pathway, and so caspase-dependent apoptosis. JAK2 is the most common mutated gene in bcr-abl-negative myeloproliferative disorders; the JAK2V617F gain-of-function mutation involves a valine-to-phenylalanine modification at position 617. The JAK-STAT signaling pathway is a major mediator of cytokine activity.

The compound 11-(2-pyrrolidin-1-yl-ethoxy)-14,19-dioxa-5,7,26-triaza-tetracyclo[19.3.1.1(2,6).1(8,12)]heptacosa-1(25),2(26),3,5,8,10,12(27),16,21,23-decaene (Compound I) was first described in PCT/SG2006/000352 and shows significant promise as a pharmaceutically active agent for the treatment of a number of medical conditions and clinical development of this compound is underway based on the activity profiles demonstrated by the compound.

• In the development of a drug suitable for mass production and ultimately commercial use acceptable levels of drug activity against the target of interest is only one of the important variables that must be considered. For example, in the formulation of pharmaceutical compositions it is imperative that the pharmaceutically active substance be in a form that can be reliably reproduced in a commercial manufacturing process and which is robust enough to withstand the conditions to which the pharmaceutically active substance is exposed.
• In a manufacturing sense it is important that during commercial manufacture the manufacturing process of the pharmaceutically active substance be such that the same material is reproduced when the same manufacturing conditions are used. In addition it is desirable that the pharmaceutically active substance exists in a solid form where minor changes to the manufacturing conditions do not lead to major changes in the solid form of the pharmaceutically active substance produced. For example it is important that the manufacturing process produce material having the same crystalline properties on a reliable basis and also produce material having the same level of hydration.
• In addition it is important that the pharmaceutically active substance be stable both to degradation, hygroscopicity and subsequent changes to its solid form. This is important to facilitate the incorporation of the pharmaceutically active substance into pharmaceutical formulations. If the pharmaceutically active substance is hygroscopic (“sticky”) in the sense that it absorbs water (either slowly or over time) it is almost impossible to reliably formulate the pharmaceutically active substance into a drug as the amount of substance to be added to provide the same dosage will vary greatly depending upon the degree of hydration. Furthermore variations in hydration or solid form (“polymorphism”) can lead to changes in physico-chemical properties, such as solubility or dissolution rate, which can in turn lead to inconsistent oral absorption in a patient.
• Accordingly, chemical stability, solid state stability, and “shelf life” of the pharmaceutically active substance are very important factors. In an ideal situation the pharmaceutically active substance and any compositions containing it, should be capable of being effectively stored over appreciable periods of time, without exhibiting a significant change in the physico-chemical characteristics of the active substance such as its activity, moisture content, solubility characteristics, solid form and the like.
• In relation to 11-(2-pyrrolidin-1-yl-ethoxy)-14,19-dioxa-5,7,26-triaza-tetracyclo[19.3.1.1(2,6).1(8,12)]heptacosa-1(25),2(26),3,5,8,10,12(27),16,21,23-decaene initial studies were carried out on the hydrochloride salt and indicated that polymorphism was prevalent with the compound being found to adopt more than one crystalline form depending upon the manufacturing conditions. In addition it was observed that the moisture content and ratio of the polymorphs varied from batch to batch even when the manufacturing conditions remained constant. These batch-to-batch inconsistencies and the exhibited hygroscopicity made the hydrochloride salt less desirable from a commercial viewpoint.
• Accordingly it would be desirable to develop one or more salts of 11-(2-pyrrolidin-1-yl-ethoxy)-14,19-dioxa-5,7,26-triaza-tetracyclo[19.3.1.1(2,6).1(8,12)]heptacosa-1(25),2(26),3,5,8,10,12(27),16,21,23-decaene which overcome or ameliorate one or more of the above identified problems.

PATENT

US 2011263616

http://www.google.com/patents/US20110263616

PATENT

http://www.google.com/patents/US8415338

Representative Procedure for the Synthesis of Compounds Type (XVIIId) [3-(2-Chloro-pyrimidin-4-yl)-phenyl]-methanol (XIIIa2)

Compound (XIIIa2) was obtained using the same procedure described for compound (XIIIa1); LC-MS (ESI positive mode) m/z 221 ([M+H]⁺).

4-(3-Allyloxymethyl-phenyl)-2-chloro-pyrimidine (XVa2)

Compound (XVa2) was obtained using the same procedure described for compound (XVa1); LC-MS (ESI positive mode) m/z 271 ([M+H]⁺).

[4-(3-Allyloxymethyl-phenyl)-pyrimidin-2-yl]-[3-allyloxymethyl-4-(2-pyrrolidin-1-yl-ethoxy)-phenyl]-amine (XVIId1)

Compound (XVIId1) was obtained using the same procedure described for compound (XVIIb1); LC-MS (ESI positive mode) m/z 501.

Macrocycle Example 3 Compound 13

Compound (13) was obtained using the same procedure described for compound (1) HPLC purity at 254 nm: 99%; LC-MS (ESI positive mode) m/z 473 ([M+H]⁺); ¹H NMR (MeOD-d₄) δ 8.79 (d, 1H), 8.46 (d, 1H), 8.34-8.31 (m, 1H), 7.98-7.96 (m, 1H), 7.62-7.49 (m, 2H), 7.35 (d, 1H), 7.15-7.10 (m, 1H), 7.07-7.02 (m, 1H), 5.98-5.75 (m, 2H, 2×=CH), 4.67 (s, 2H), 4.67 (s, 2H), 4.39-4.36 (m, 2H), 4.17 (d, 2H), 4.08 (d, 2H), 3.88-3.82 (m, 2H), 3.70 (t, 2H), 2.23-2.21 (m, 2H), 2.10-2.07 (m, 2H).

References

• “International Nonproprietary Names for Pharmaceutical Substances (INN) List 104” (PDF). WHO Drug Information 24 (4): 386. 2010.
• 2
• “JAK-Inhibitoren: Neue Wirkstoffe für viele Indikationen”. Pharmazeutische Zeitung (in German) (21). 2013.
• 3
• William, A. D.; Lee, A. C. -H.; Blanchard, S. P.; Poulsen, A.; Teo, E. L.; Nagaraj, H.; Tan, E.; Chen, D.; Williams, M.; Sun, E. T.; Goh, K. C.; Ong, W. C.; Goh, S. K.; Hart, S.; Jayaraman, R.; Pasha, M. K.; Ethirajulu, K.; Wood, J. M.; Dymock, B. W. (2011). “Discovery of the Macrocycle 11-(2-Pyrrolidin-1-yl-ethoxy)-14,19-dioxa-5,7,26-triaza-tetracyclo[19.3.1.1(2,6).1(8,12)]heptacosa-1(25),2(26),3,5,8,10,12(27),16,21,23-decaene (SB1518), a Potent Janus Kinase 2/Fms-Like Tyrosine Kinase-3 (JAK2/FLT3) Inhibitor for the Treatment of Myelofibrosis and Lymphoma”. Journal of Medicinal Chemistry 54 (13): 4638–58. doi:10.1021/jm200326p. PMID 21604762.
• 4
• Poulsen, A.; William, A.; Blanchard, S. P.; Lee, A.; Nagaraj, H.; Wang, H.; Teo, E.; Tan, E.; Goh, K. C.; Dymock, B. (2012). “Structure-based design of oxygen-linked macrocyclic kinase inhibitors: Discovery of SB1518 and SB1578, potent inhibitors of Janus kinase 2 (JAK2) and Fms-like tyrosine kinase-3 (FLT3)”. Journal of Computer-Aided Molecular Design 26 (4): 437–50. doi:10.1007/s10822-012-9572-z. PMID 22527961.
• 5

http://www.pmlive.com/pharma_news/baxter_licenses_cancer_drug_from_cti_in_$172m_deal_519143

Pacritinib

Systematic (IUPAC) name
(16E)-11-[2-(1-Pyrrolidinyl)ethoxy]-14,19-dioxa-5,7,26-triazatetracyclo[19.3.1.12,6.18,12]heptacosa-1(25),2(26),3,5,8,10,12(27),16,21,23-decaene
Clinical data
Legal status	Investigational
Routes of administration	Oral
Identifiers
ATC code	None
PubChem	CID: 46216796
ChemSpider	28518965
ChEMBL	CHEMBL2035187
Synonyms	SB1518
Chemical data
Formula	C28H32N4O3
Molecular mass	472.58 g/mol

///////

c1cc2cc(c1)-c3ccnc(n3)Nc4ccc(c(c4)COC/C=C/COC2)OCCN5CCCC5

C1CCN(C1)CCOC2=C3COCC=CCOCC4=CC=CC(=C4)C5=NC(=NC=C5)NC(=C3)C=C2