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At least 19 recordsLinked to original sources
PubMed2005

Action of the Src family kinase inhibitor, dasatinib (BMS-354825), on human prostate cancer cells.

Src family kinases (SFK) are currently being investigated as targets for treatment strategies in various cancers. The novel SFK/Abl inhibitor, dasatinib (BMS-354825), is a promising therapeutic agent with oral bioavailability. Dasatinib has been shown to inhibit growth of Bcr-Abl-dependent chronic myeloid leukemia xenografts in nude mice. Dasatinib also has been shown to have activity against cultured human prostate and breast cancer cells. However, the molecular mechanism by which dasatinib acts on epithelial tumor cells remains unknown. In this study, we show that dasatinib blocks the kinase activities of the SFKs, Lyn, and Src, in human prostate cancer cells at low nanomolar concentrations. Moreover, focal adhesion kinase and Crk-associated substrate (p130(CAS)) signaling downstream of SFKs are also inhibited at similar concentrations of dasatinib. Consistent with inhibition of these signaling pathways, dasatinib suppresses cell adhesion, migration, and invasion of prostate cancer cells at low nanomolar concentrations. Therefore, dasatinib has potential as a therapeutic agent for metastatic prostate cancers harboring activated SFK and focal adhesion kinase signaling.

Cell Adhesion↗
PubMed2006

Dasatinib (BMS-354825) pharmacokinetics and pharmacodynamic biomarkers in animal models predict optimal clinical exposure.

PURPOSE: Chronic myeloid leukemia (CML) is caused by reciprocal translocation between chromosomes 9 and 22, forming BCR-ABL, a constitutively activated tyrosine kinase. Imatinib mesylate, a selective inhibitor of BCR-ABL, represents current frontline therapy for CML; however, emerging evidence suggests that drug resistance to imatinib may limit its long-term success. To improve treatment options, dasatinib (BMS-354825) was developed as a novel, oral, multi-targeted kinase inhibitor of BCR-ABL and SRC family kinases. To date, dasatinib has shown promising anti-leukemic activity in preclinical models of CML and in phase I/II clinical studies in patients with imatinib-resistant or imatinib-intolerant disease. EXPERIMENTAL DESIGN: The pharmacokinetic and pharmacodynamic biomarkers of dasatinib were investigated in K562 human CML xenografts grown s.c. in severe combined immunodeficient mice. Tumoral levels of phospho-BCR-ABL/phospho-CrkL were determined by Western blot. RESULTS: Following a single oral administration of dasatinib at a preclinical efficacious dose of 1.25 or 2.5 mg/kg, tumoral phospho-BCR-ABL/phospho-CrkL were maximally inhibited at approximately 3 hours and recovered to basal levels by 24 hours. The time course and extent of the inhibition correlated with the plasma levels of dasatinib in mice. Pharmacokinetic/biomarker modeling predicted that the plasma concentration of dasatinib required to inhibit 90% of phospho-BCR-ABL in vivo was 10.9 ng/mL in mice and 14.6 ng/mL in humans, which is within the range of concentrations achieved in CML patients who responded to dasatinib treatment in the clinic. CONCLUSIONS: Phospho-BCR-ABL/phospho-CrkL are likely to be useful clinical biomarkers for the assessment of BCR-ABL kinase inhibition by dasatinib.

Adaptor Proteins, Signal Transducing↗
PubMed2006

Identification of potential biomarkers for measuring inhibition of Src kinase activity in colon cancer cells following treatment with dasatinib.

Elevated levels of Src kinase expression have been found in a variety of human epithelial cancers. Most notably in colon cancer, elevated Src expression correlates with malignant potential and is also associated with metastatic disease. Dasatinib (BMS-354825) is a novel, orally active, multi-targeted kinase inhibitor that targets Src family kinases and is currently under clinical evaluation for the treatment of solid tumors. However, the effects of dasatinib on epithelial tumors are not fully understood. We show that concentrations of dasatinib that inhibit Src activity do not inhibit proliferation in 10 of 12 colon cancer cells lines. However, inhibition of integrin-dependent adhesion and migration by dasatinib correlated with inhibition of Src activity, suggesting that dasatinib may have anti-invasive or anti-metastatic activity and antiproliferative activity in epithelial tumors. Using phospho-specific antibodies, we show that inhibition of Src activity in colon cancer cell lines correlates with reduced phosphorylation of focal adhesion kinase and paxillin on specific Src-dependent phosphorylation sites. We have validated the use of phospho-specific antibodies against Src Tyr(419) and paxillin Tyr(118) as biomarkers of dasatinib activity in vivo. Colon carcinoma-bearing mice treated with dasatinib showed a decrease in both phospho-Src Tyr(419) and phospho-paxillin Tyr(118) in peripheral blood mononuclear cells, which correlated with inhibition of Src activity in the colon tumors. Thus, peripheral blood mononuclear cells may provide a useful surrogate tissue for biomarker studies with dasatinib using inhibition of Src Tyr(419) and paxillin Tyr(118) phosphorylation as read-outs of Src activity.

Animals↗
PubMed2006

Dasatinib (BMS-354825) inhibits KITD816V, an imatinib-resistant activating mutation that triggers neoplastic growth in most patients with systemic mastocytosis.

Mastocytosis is associated with an activating mutation in the KIT oncoprotein (KITD816V) that results in autophosphorylation of the KIT receptor in a ligand-independent manner. This mutation is inherently resistant to imatinib and, to date, there remains no effective curative therapy for systemic mastocytosis associated with KITD816V. Dasatinib (BMS-354825) is a novel orally bioavailable SRC/ABL inhibitor that has activity against multiple imatinib-resistant BCR-ABL isoforms in vitro that is presently showing considerable promise in early-phase clinical trials of chronic myeloid leukemia (CML). Pharmacokinetic analysis suggests that high nanomolar concentrations of dasatinib can be achieved safely in humans. In this study, we demonstrate significant inhibitory activity of dasatinib against both wild-type KIT and the KITD816V mutation in the nanomolar range in in vitro and cell-based kinase assays. Additionally, dasatinib leads to growth inhibition of a KITD816V-harboring human masto-cytosis cell line. Significantly, dasatinib selectively kills primary neoplastic bone marrow mast cells from patients with systemic mastocytosis while sparing other hematopoietic cells. Computer modeling suggests that the KITD816V mutation destabilizes the inactive conformation of the KIT activation loop to which imatinib binds, but it is not predicted to impair binding of KIT by dasatinib. Based upon our results, further evaluation of dasatinib for the treatment of systemic masto-cytosis in clinical trials is warranted. Moreover, dasatinib may be of clinical utility in other disease settings driven by activating KIT mutations.

Animals↗
PubMed2006

Cotreatment with vorinostat (suberoylanilide hydroxamic acid) enhances activity of dasatinib (BMS-354825) against imatinib mesylate-sensitive or imatinib mesylate-resistant chronic myelogenous leukemia cells.

PURPOSE: We determined the effects of vorinostat [suberoylanilide hydroxamic acid (SAHA)] and/or dasatinib, a dual Abl/Src kinase (tyrosine kinase) inhibitor, on the cultured human (K562 and LAMA-84) or primary chronic myelogenous leukemia (CML) cells, as well as on the murine pro-B BaF3 cells with ectopic expression of the unmutated and kinase domain-mutant forms of Bcr-Abl. EXPERIMENTAL DESIGN: Following exposure to dasatinib and/or vorinostat, apoptosis, loss of clonogenic survival, as well as the activity and levels of Bcr-Abl and its downstream signaling proteins were determined. RESULTS: Treatment with dasatinib attenuated the levels of autophosphorylated Bcr-Abl, p-CrkL, phospho-signal transducer and activator of transcription 5 (p-STAT5), p-c-Src, and p-Lyn; inhibited the activity of Lyn and c-Src; and induced apoptosis of the cultured CML cells. Combined treatment of cultured human CML and BaF3 cells with vorinostat and dasatinib induced more apoptosis than either agent alone, as well as synergistically induced loss of clonogenic survival, which was associated with greater depletion of Bcr-Abl, p-CrkL, and p-STAT5 levels. Cotreatment with dasatinib and vorinostat also attenuated the levels of Bcr-AblE255K and Bcr-AblT315I and induced apoptosis of BaF3 cells with ectopic expression of the mutant forms of Bcr-Abl. Finally, cotreatment of the primary CML cells with vorinostat and dasatinib induced more loss of cell viability and depleted Bcr-Abl or Bcr-AblT315I, p-STAT5, and p-CrkL levels than either agent alone. CONCLUSIONS: As shown here, the preclinical in vitro activity of vorinostat and dasatinib against cultured and primary CML cells supports the in vivo testing of the combination in imatinib mesylate-sensitive and imatinib mesylate-resistant CML cells.

Animals↗
PubMed2006

Dasatinib (BMS-354825) selectively induces apoptosis in lung cancer cells dependent on epidermal growth factor receptor signaling for survival.

Mutations of the epidermal growth factor receptor (EGFR) selectively activate Akt and signal transducer and activator of transcription (STAT) pathways that are important in lung cancer cell survival. Src family kinases can cooperate with receptor tyrosine kinases to signal through downstream molecules, such as phosphatidylinositol 3-kinase/PTEN/Akt and STATs. Based on the importance of EGFR signaling in lung cancer, the known cooperation between EGFR and Src proteins, and evidence of elevated Src activity in human lung cancers, we evaluated the effectiveness of a novel orally bioavailable Src inhibitor dasatinib (BMS-324825) in lung cancer cell lines with defined EGFR status. Here, we show that cell fate (death versus growth arrest) in lung cancer cells exposed to dasatinib is dependent on EGFR status. In cells with EGFR mutation that are dependent on EGFR for survival, dasatinib reduces cell viability through the induction of apoptosis while having minimal apoptotic effect on cell lines with wild-type (WT) EGFR. The induction of apoptosis in these EGFR-mutant cell lines corresponds to down-regulation of activated Akt and STAT3 survival proteins. In cell lines with WT or resistant EGFR mutation that are not sensitive to EGFR inhibition, dasatinib induces a G(1) cell cycle arrest with associated changes in cyclin D and p27 proteins, inhibits activated FAK, and prevents tumor cell invasion. Our results show that dasatinib could be effective therapy for patients with lung cancers through disruption of cell growth, survival, and tumor invasion. Our results suggest EGFR status is important in deciding cell fate in response to dasatinib.

Apoptosis↗
PubMed2006

Dasatinib: BMS 354825.

Dasatinib [BMS 354825] is an orally active, small molecule, dual inhibitor of both SRC and ABL kinases that is under development with Bristol-Myers Squibb for the treatment of patients with chronic myelogenous leukaemia (CML) and imatinib-acquired resistance/intolerance. While imatinib remains a frontline therapy for CML, patients with advanced disease frequently develop resistance to imatinib therapy through multiple mechanisms. These mechanisms include insufficient potency at therapeutic doses, activation of alternate oncogenic pathways, and overexpression of the multidrug-resistant gene. One of the possible causes of imatinib-acquired resistance is associated with increased expression of the SRC-related kinase Lyn and loss of BCR-ABL dependence arising from sequence mutations. In December 2005, Bristol-Myers Squibb announced that it has completed the rolling NDA submission to the US FDA for dasatinib in the treatment of CML in chronic, accelerated or blast phases, as well as Philadelphia chromosome-positive (Ph+) acute lymphoblastic leukaemia (ALL) in patients with resistance or intolerance to prior treatment. At the Bristol-Myers Squibb R&D Day in May 2005, the company stated that it plans to evaluate dasatinib in solid tumours. In in vitro assays, dasatinib induced apoptosis and had potent activity in the imatinib-resistant tumour cells lines and CML patient specimens. It effectively inhibited the proliferation of cells expressing nearly all imatinib-resistant isoforms. In vivo, dasatinib has shown efficacy, with no apparent toxicity, when administered orally in SCID mice with xenografts of imatinib-sensitive and resistant human CML cells lines. Dasatinib is also undergoing preclinical evaluation for its potential as a therapy against multiple myeloma. Bristol-Myers Squibb has a composition-of-matter patent covering this research approach that will expire in 2020.

Animals↗
PubMed2007

BCR-ABL mutant kinetics in CML patients treated with dasatinib.

Dasatinib is efficient in vitro against most of CML cells harboring ABL kinase domain mutations and induces high rates of response in imatinib-resistant CML patients. Here, we monitored the mutated BCR-ABL transcripts during the follow-up of 12 CML patients treated with dasatinib. We identified four groups of patients based on their sensitivity to dasatinib. Clinical responses were correlated to the in vitro sensitivity of BCR-ABL mutants to dasatinib, however, some discrepancies were observed in a subfraction of CML patients, suggesting subtle differences between in vitro observations and clinical entities and/or the onset of other mechanisms responsible for dasatinib resistance.

Adult↗
PubMed2006

Dasatinib (BMS-354825), a dual SRC/ABL kinase inhibitor, inhibits the kinase activity of wild-type, juxtamembrane, and activation loop mutant KIT isoforms associated with human malignancies.

Activating mutations of the activation loop of KIT are associated with certain human neoplasms, including the majority of patients with systemic mast cell disorders, as well as cases of seminoma, acute myelogenous leukemia (AML), and gastrointestinal stromal tumors (GISTs). The small-molecule tyrosine kinase inhibitor imatinib mesylate is a potent inhibitor of wild-type (WT) KIT and certain mutant KIT isoforms and has become the standard of care for treating patients with metastatic GIST. However, KIT activation loop mutations involving codon D816 that are typically found in AML, systemic mastocytosis, and seminoma are insensitive to imatinib mesylate (IC50 > 5-10 micromol/L), and acquired KIT activation loop mutations can be associated with imatinib mesylate resistance in GIST. Dasatinib (formerly BMS-354825) is a small-molecule, ATP-competitive inhibitor of SRC and ABL tyrosine kinases with potency in the low nanomolar range. Some small-molecule SRC/ABL inhibitors also have potency against WT KIT kinase. Therefore, we hypothesized that dasatinib might inhibit the kinase activity of both WT and mutant KIT isoforms. We report herein that dasatinib potently inhibits WT KIT and juxtamembrane domain mutant KIT autophosphorylation and KIT-dependent activation of downstream pathways important for cell viability and cell survival, such as Ras/mitogen-activated protein kinase, phosphoinositide 3-kinase/Akt, and Janus-activated kinase/signal transducers and activators of transcription. Furthermore, dasatinib is a potent inhibitor of imatinib-resistant KIT activation loop mutants and induces apoptosis in mast cell and leukemic cell lines expressing these mutations (potency against KIT D816Y >> D816F > D816V). Our studies suggest that dasatinib may have clinical efficacy against human neoplasms that are associated with gain-of-function KIT mutations.

Amino Acid Substitution↗
PubMed2005

Dasatinib (BMS-354825) tyrosine kinase inhibitor suppresses invasion and induces cell cycle arrest and apoptosis of head and neck squamous cell carcinoma and non-small cell lung cancer cells.

PURPOSE: Epithelial tumors, including non-small cell lung cancer (NSCLC) and head and neck squamous cell carcinoma (HNSCC), present clinical challenges. One potential target for systemic therapy is Src family nonreceptor tyrosine kinases, which are overexpressed in these tumors and induce pleiotropic effects, including increased proliferation, enhanced survival, stimulation of angiogenesis, and changes in motility. Dasatinib (BMS-354825), an ATP-competitive, small molecule tyrosine kinase inhibitor, suppresses the activity of these kinases at subnanomolar concentrations. Therefore, we tested the antitumor effects of this inhibitor in vitro to determine whether in vivo analyses were warranted. EXPERIMENTAL DESIGN: The antitumor effects of dasatinib on HNSCC and NSCLC cells were evaluated using assays to measure cell cycle progression, apoptosis, migration, and invasion. Western blotting was used to monitor its effects on cell signaling. RESULTS: Dasatinib inhibited migration and invasion in all cell lines and induced cell cycle arrest (blocking the G1-S transition) and apoptosis in some lines. The effects on migration and invasion correlated with the inhibition of Src and downstream mediators of adhesion [e.g., focal adhesion kinase (FAK), p130, and paxillin], and the cell cycle effects and apoptosis correlated with the induction of p27 and the dephosphorylation of Rb. Dasatinib also induced morphologic changes that were consistent with an upstream role for Src in regulating focal adhesion complexes. CONCLUSIONS: This study showed that Src inhibition in HNSCC and NSCLC has antitumor effects in vitro. This suggests that dasatinib would have therapeutic activity against these tumors. Clinical studies in these tumor types are warranted.

Adenosine Triphosphate↗
PubMed2006

Dasatinib (BMS-354825) targets an earlier progenitor population than imatinib in primary CML but does not eliminate the quiescent fraction.

Dasatinib (BMS-354825), a novel dual SRC/BCR-ABL kinase inhibitor, exhibits greater potency than imatinib mesylate (IM) and inhibits the majority of kinase mutations in IM-resistant chronic myeloid leukemia (CML). We have previously demonstrated that IM reversibly blocks proliferation but does not induce apoptosis of primitive CML cells. Here, we have attempted to overcome this resistance with dasatinib. Primitive IM-resistant CML cells showed only single-copy BCR-ABL but expressed significantly higher BCR-ABL transcript levels and BCR-ABL protein compared with more mature CML cells (P = .031). In addition, CrKL phosphorylation was higher in the primitive CD34(+)CD38(-) than in the total CD34(+) population (P = .002). In total CD34(+) CML cells, IM inhibited phosphorylation of CrKL at 16 but not 72 hours, consistent with enrichment of an IM-resistant primitive population. CD34(+)CD38(-) CML cells proved resistant to IM-induced inhibition of CrKL phosphorylation and apoptosis, whereas dasatinib led to significant inhibition of CrKL phosphorylation. Kinase domain mutations were not detectable in either IM or dasatinib-resistant primitive CML cells. These data confirm that dasatinib is more effective than IM within the CML stem cell compartment; however, the most primitive quiescent CML cells appear to be inherently resistant to both drugs.

Adaptor Proteins, Signal Transducing↗
PubMed2006

Comparison of imatinib mesylate, dasatinib (BMS-354825), and nilotinib (AMN107) in an N-ethyl-N-nitrosourea (ENU)-based mutagenesis screen: high efficacy of drug combinations.

BMS-354825 (dasatinib) and AMN107 (nilotinib) are potent alternate Abl inhibitors with activity against many imatinib mesylate-resistant BCR-ABL kinase domain (KD) mutants, except T315I. We used N-ethyl-N-nitrosourea (ENU)-exposed Ba/F3-p210(BCR-ABL) cells to compare incidence and types of KD mutants emerging in the presence of imatinib mesylate, dasatinib, and nilotinib, alone and in dual combinations. Although ENU is expected to induce mutations in multiple proteins, resistant clones were almost exclusively BCR-ABL KD mutant at relevant concentrations of nilotinib and dasatinib, consistent with a central role of KD mutations for resistance to these drugs. Twenty different mutations were identified with imatinib mesylate, 10 with nilotinib (including only 1 novel mutation, E292V) and 9 with dasatinib. At intermediate drug levels the spectrum narrowed to F317V and T315I for dasatinib and Y253H, E255V, and T315I for nilotinib. Thus, cross-resistance is limited to T315I, which is also the only mutant isolated at drug concentrations equivalent to maximal achievable plasma trough levels. With drug combinations maximal suppression of resistant clone outgrowth was achieved at lower concentrations compared with single agents, suggesting that such combinations may be equipotent to higher-dose single agents. However, sequencing uniformly revealed T315I, consistent with the need for a T315I inhibitor, to completely block resistance.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed2006

Dasatinib (BMS-354825) is active in Philadelphia chromosome-positive chronic myelogenous leukemia after imatinib and nilotinib (AMN107) therapy failure.

Developing strategies to counteract imatinib resistance constitutes a challenge in chronic myelogenous leukemia (CML). Therapy with the tyrosine kinase inhibitors nilotinib (AMN107) and dasatinib (BMS-354825) has produced high rates of hematologic and cytogenetic response. Src kinase activation has been linked to Bcr-Abl-mediated leukemogenesis and CML progression. In addition to binding Abl kinase with less stringent conformational requirements than imatinib, dasatinib is a potent Src kinase inhibitor. In the current study, we report on 23 patients with CML (19 of them in accelerated or blastic phases) treated with dasatinib after treatment failure with both imatinib and nilotinib. More than half (13; 57%) of 23 patients responded to dasatinib: 10 (43%) had a complete hematologic response (CHR), including 7 (30%) who had a cytogenetic response (2 complete, 4 partial, and 1 minor). These results suggest that dasatinib may be active in some patients after failure with both imatinib and nilotinib.

Adult↗
PubMed2006

Dasatinib induces complete hematologic and cytogenetic responses in patients with imatinib-resistant or -intolerant chronic myeloid leukemia in blast crisis.

The prognosis for patients with chronic myeloid leukemia (CML) in myeloid blast crisis (MBC) or lymphoid blast crisis (LBC) remains poor. Although imatinib can induce responses in a subset of these patients, resistance to the drug develops rapidly. Dasatinib is a novel, oral, multitargeted kinase inhibitor of BCR-ABL and SRC family kinases. After promising phase 1 results, we report the results of phase 2 clinical trials of dasatinib in patients with imatinib-resistant or -intolerant blast crisis CML (MBC, n = 74; LBC, n = 42). At the 8-month follow-up, dasatinib induced major hematologic responses (MaHRs) in 34% and 31% of MBC- and LBC-CML patients and major cytogenetic responses (MCyRs) in 31% and 50% of these patients, respectively. Most (86%) of these MCyRs were complete cytogenetic responses (CCyRs). Responses were rapid and durable: 88% and 46%, respectively, of MBC- and LBC-CML patients achieving MaHR had not experienced disease progression at the 8-month follow-up. Response rates were similar in patients with and without BCR-ABL mutations known to confer resistance to imatinib. Dasatinib was well tolerated. Nonhematologic adverse events were mild to moderate. Cytopenias were common and could be managed by dose modification. Dasatinib is highly active and produces hematologic and cytogenetic responses in a significant number of patients with imatinib-resistant or -intolerant MBC- and LBC-CML. These trials were registered at www.clinicaltrials.gov as #CA180006 and #CA180015.

Administration, Oral↗
PubMed2006

Dasatinib induces notable hematologic and cytogenetic responses in chronic-phase chronic myeloid leukemia after failure of imatinib therapy.

Although imatinib induces marked responses in patients with chronic myeloid leukemia (CML), resistance is increasingly problematic, and treatment options for imatinib-resistant or -intolerant CML are limited. Dasatinib, a novel, highly potent, oral, multitargeted kinase inhibitor of BCR-ABL and SRC family kinases, induced cytogenetic responses in a phase 1 study in imatinib-resistant or -intolerant CML and was well tolerated. Initial results are presented from a phase 2 study of 186 patients with imatinib-resistant or -intolerant chronic-phase CML (CML-CP) designed to further establish the efficacy and safety of dasatinib (70 mg twice daily). At 8-months' follow-up, dasatinib induced notable responses, with 90% and 52% of patients achieving complete hematologic and major cytogenetic responses (MCyR), respectively. Responses were long lasting: only 2% of patients achieving MCyR progressed or died. Importantly, comparable responses were achieved by patients carrying BCR-ABL mutations conferring imatinib resistance. Dasatinib also induced molecular responses, reducing BCR-ABL/ABL transcript ratios from 66% at baseline to 2.6% at 9 months. Nonhematologic adverse events were generally mild to moderate, and most cytopenias were effectively managed with dose modifications. Cross-intolerance with imatinib was not evident. To conclude, dasatinib induces notable responses in imatinib-resistant or -intolerant CML-CP, is well tolerated, and represents a promising therapeutic option for these patients. This trial was registered at www.clinicaltrials.gov as CA180013.

Adult↗
PubMed2006

Dasatinib in imatinib-resistant Philadelphia chromosome-positive leukemias.

BACKGROUND: The BCR-ABL tyrosine kinase inhibitor imatinib is effective in Philadelphia chromosome-positive (Ph-positive) leukemias, but relapse occurs, mainly as a result of the outgrowth of leukemic subclones with imatinib-resistant BCR-ABL mutations. We evaluated dasatinib, a BCR-ABL inhibitor that targets most imatinib-resistant BCR-ABL mutations, in patients with chronic myelogenous leukemia (CML) or Ph-positive acute lymphoblastic leukemia (ALL). METHODS: Patients with various phases of CML or with Ph-positive ALL who could not tolerate or were resistant to imatinib were enrolled in a phase 1 dose-escalation study. Dasatinib (15 to 240 mg per day) was administered orally in four-week treatment cycles, once or twice daily. RESULTS: A complete hematologic response was achieved in 37 of 40 patients with chronic-phase CML, and major hematologic responses were seen in 31 of 44 patients with accelerated-phase CML, CML with blast crisis, or Ph-positive ALL. In these two phases, the rates of major cytogenetic response were 45 percent and 25 percent, respectively. Responses were maintained in 95 percent of patients with chronic-phase disease and in 82 percent of patients with accelerated-phase disease, with a median follow-up more than 12 months and 5 months, respectively. Nearly all patients with lymphoid blast crisis and Ph-positive ALL had a relapse within six months. Responses occurred among all BCR-ABL genotypes, with the exception of the T315I mutation, which confers resistance to both dasatinib and imatinib in vitro. Myelosuppression was common but not dose-limiting. CONCLUSIONS: Dasatinib induces hematologic and cytogenetic responses in patients with CML or Ph-positive ALL who cannot tolerate or are resistant to imatinib. (ClinicalTrials.gov number, NCT00064233 [ClinicalTrials.gov].).

Adolescent↗
PubMed2006

The structure of Dasatinib (BMS-354825) bound to activated ABL kinase domain elucidates its inhibitory activity against imatinib-resistant ABL mutants.

Chronic myeloid leukemia (CML) is caused by the constitutively activated tyrosine kinase breakpoint cluster (BCR)-ABL. Current frontline therapy for CML is imatinib, an inhibitor of BCR-ABL. Although imatinib has a high rate of clinical success in early phase CML, treatment resistance is problematic, particularly in later stages of the disease, and is frequently mediated by mutations in BCR-ABL. Dasatinib (BMS-354825) is a multitargeted tyrosine kinase inhibitor that targets oncogenic pathways and is a more potent inhibitor than imatinib against wild-type BCR-ABL. It has also shown preclinical activity against all but one of the imatinib-resistant BCR-ABL mutants tested to date. Analysis of the crystal structure of dasatinib-bound ABL kinase suggests that the increased binding affinity of dasatinib over imatinib is at least partially due to its ability to recognize multiple states of BCR-ABL. The structure also provides an explanation for the activity of dasatinib against imatinib-resistant BCR-ABL mutants.

Animals↗
PubMed2006

Targeting ABL and SRC kinases in chronic myeloid leukemia: experience with dasatinib.

Mutations within the ABL kinase domain and overexpression of SRC family kinases have been identified among the known mechanisms of resistance to imatinib in chronic myeloid leukemia (CML). The development of agents with dual inhibitory activity against SRC and ABL kinases is one approach to overcome imatinib resistance. One such agent, dasatinib (formerly BMS-354825), is approximately 300-fold more potent against BCR-ABL than imatinib, and is active against all tested ABL mutant isoforms, except for T315I. Dasatinib has demonstrated high efficacy in Phase I and II studies in patients with CML following failure of imatinib therapy. Studies exploring the efficacy of dasatinib as front-line therapy in patients with BCR-ABL-expressing hematologic malignancies are underway.

Benzamides↗