Dasatinib

Dasatinib (Spry cel) TKI Bcr-Abl, Src family kinases, c-Kit, PDGFR, EphB4 Inhibition of kinase activity - ATP-competitive, binding to an active conformation CML ALL... 

Note that application in the particular indications is usually restricted either to patients expressing the target (e.g. trastuzumab, cetuximab, lapatinib, imatinib) and/or after failure of prior therapies (e.g. cetuximab, erlotinib, lapatinib, sutinib, dasatinib). Furthermore, for cancer treatment most tyrosine kinase inhibitors are applied in combination with conventional chemotherapeutic drugs, such as fluorouracil, taxanes, platin-based regimens, anthracylines and irinotecan or radiotherapy. 

Several other inhibitors of nonreceptor PTKs are currently in development but only a few of them are studied in clinical trials. Noteworthy, Dasatinib does not only inhibit c-Abl, but also potently blocks Src activity, a property that may contribute to its beneficial clinical effects in CML. Other kinase inhibitors being developed that inhibit c-Abl and/or Src are AZD-0530, AP-23994, PD-0183805, SU-6656, and Bosutinib (SKI-606). Furthermore, peptidomimetic SH2 domain inhibitors for Src, such as AP-22408 have been designed that decrease bone resorption and may be promising drugs to treat osteoporosis and other bone diseases, such as Paget s disease and osteolytic bone metastasis. 

The M20 metabolite is a major circulating metabolite of dasatinib (SPRY CEL) in humans [77]. A large quantity of M20 was needed to serve as an analytical standard, but was not readily accessible by mammalian bioreactors or chemical synthesis. Microbial biotransformation was used to make the metabolite to support the development of dasatinib [58]. 

Selection of active strains was achieved using the 20-well screening plate system discussed in Section 9.3.3. One screening plate containing 20 actinomycetes strains in malt extract medium was incubated for 2 days at 28 °C and 275 rpm. Dasatinib (2 /xLof a 100 mM solution in DMSO) was added to each well and the plate was incubated for one additional day at 28 °C. Then 1 mL of methanol was added to each well and the plate incubated at 28 °C at 150 rpm for 10 min and centrifuged at 3000 rpm for 15 min. The supernatant was analyzed by HPLC-UV-MS. LC-UV-MS data showed M20 and M24 were produced by seven strains, from which Streptomyces sp. SC15761 was selected for scale-up based on the yield of M20 (Figure 9.8). 

Figure 9.8 Microbial biotransformation of dasatinib with Streptomyces sp. SC15761...

A 500 mL flask containing 100 mL of the malt extract medium was inoculated with 2 mL frozen stock culture of Streptomyces sp. SC 15761 and incubated for 3 days at 28 °C and 250 rpm. Then 1 mL of the resulting culture was added to each 500 mL flask (11 in total) containing 100 mL of the malt extract broth. The cultures were incubated at 28 °C and 250 rpm for 2 days. Dasatinib (200/rL of a 48.9 mg mL-1 solution in DMSO) was then added to each of the 11 flasks. The flasks were returned to the shaker and incubated for an additional 27 h at 28 °C and 250 rpm. The reaction cultures were pooled and extracted twice, once with 1000 mL of ethyl acetate and once... 

Li, W., Josephs, J.L., Skiles, G. and Humphreys, W.G. (2008) Metabolite generation via microbial biotransformation with actinomycetes rapid screening methods and synthesis of important human metabolites of two development stage compounds, BMS-587101 and dasatinib. Drug Metabolism and Disposition The Biological Fate of Chemicals, 36, 721-730. 

Dasatinib (Sprycel ) 12 inhibits Btk (IC50 = 5 nM) as well as the basal and lipopolysaccharide (LPS)-induced secretion of TNFa and IL-6 in U937 cells [65]. However, dasatinib s promiscuity [66] makes it difficult to ascribe these functional effects to direct Btk inhibition. The dasatinib-Btk(Y551E) crystal structure indicates binding to an active conformation, similar to that observed with Abl [43]. LFM-A13,13, was first described as a Btk inhibitor more than 10 years ago [67], although its poor Btk activity (IC50 = 2.5-17 /iM) and selectivity [68] require that caution be taken in interpreting functional effects. 

Pyrimidinylaminothiazole Template-Based Inhibitor BMS-354825 (Dasatinib, Sprycel )... 

BMS-354825, which has the generic name of dasatinib, entered Phase II clinical trials in December 2004 under the START (Src/Abl Tyrosine kinase inhibition Activity Research Trial) program [ 144-147]. Dosing was initiated at 70 mg twice daily with the option of increasing the dose to 90 or 100 mg or reducing the dose to 40 or 50 mg, depending on low response or toxicity. As part of the Phase I and II trials, patients were assessed for the presence of Bcr-Abl mutations prior to treatment with BMS-354825. In a study at UCLA,... 

Note added in proof On June 29, 2006 the Food and Drug Administration (FDA) granted approval for dasatinib (Sprycel) [152]. 

McCaig AM, Cosimo E, Leach MT et al (2011) Dasatinib inhibits B cell receptor signalling in chronic lymphocytic leukaemia but novel combination approaches are required to overcome additional pro-survival microenvironmental signals. Br J Haematol 153(2) 199-211... 

Dasatinib is an oral dual BCR/ABL and Src family tyrosine kinases inhibitor approved for use in patients with chronic myelogenous leukemia after ima-tinib treatment and for the treatment of Philadelphia chromosome-positive acute lymphoblastic leukemia. Maximum plasma concentrations (Cmax) of dasatinib are observed between 0.5 and 6 hours (Tmax) following oral administration. Dasatinib is extensively metabolized in humans, primarily by the cytochrome P450 enzyme 3A4. CYP3A4 was the primary enzyme responsible for the formation of the active metabolite. The overall mean terminal half-life of dasatinib is 3-5 hours. Adverse events included mild to moderate diarrhea, peripheral edema, and headache. Neutropenia and myelosuppression were common toxic effects. 

Key Words Chronie myeloid leukemia imatinib resistanee BCR-ABLl Mutations dasatinib nilotinib tyrosine kinase inhibitors... 

The two compounds in the most advanced stages of development included dasa-tinib (BMS354825, Sprycel ) and nilotinib (AMN107, Tasigna ) (Fig. 5). Dasatinib... 

The T3151 mutation has been consistently shown to retain resistance to both dasatinib and nilotinib, and to the other pyridopyrimidine derivatives previously described. These recently developed small-molecule inhibitors have a differential activity compared to IM that relates to several key structural elements of ABLl. The ABLl kinase domain is bound by IM only in its inactive confirmation (with the activation loop in the closed position) (55). Because the inactive confirmations of ABLl and SRC are distinct, IM is able to inhibit ABLl but not SRC. 

As discussed previously, the activation loop can also flip into an active state, and the pyridopyrimidine derivatives and dasatinib are able to bind ABLl whether the activation loop is in the closed or open position (inactivated or activated) (92). Thus, binding is not affected by the activation state. Dasatinib and related compounds are also smaller in size than IM, so the P-loop must undergo major conformational changes on binding with IM, whereas only minimal changes occur with dasatinib and related compounds. This dual activity of dasatinib also raises the question as to whether its broader activity may have broader effects, including potentially adverse effects in the treatment of patients. 

A phase 1 trial of dasatinib in IM-resistant Ph+ leukemias was reported last year and dosed over a range of 15-240 mg per day in once- or twice-daily doses. Complete hematologic responses were seen in 37 of 40 patients with chronic phase CML while major hematologic responses were noted in 31 of 44 patients with Ph+ ALL and blast crisis or accelerated-phase CML. 

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