Dasatinib: A Guide to Its Use in Chronic Myeloid Leukemia in the EU

Dasatinib: a potential tyrosine kinase inhibitor to fight against multiple cancer malignancies

Dasatinib is the 2nd generation TKI (Tyrosine Kinase Inhibitor) having the potential to treat numerous forms of leukemic and cancer patients and it is 300 times more potent than imatinib. Cancer is the major cause of death globally and need to enumerate novel strategies to coping with it. Various novel therapeutics introduced into the market for ease in treating various forms of cancer. We reviewed and evaluated all the related aspects of dasatinib, which can enhance the knowledge about dasatinib therapeutics methodology, pharmacodynamic and pharmacokinetics, side effects, advantages, disadvantages, various kinds of interactions and its novel formulations as well.

[Pharmacokinetics of generic dasatinib in the management of chronic myeloid leukemia in the choronie phase]

Objective: To evaluate the pharmacokinetics and bioequivalence of generic dasatinib in patients with chronic myeloid leukemia in the choronie phase (CML-CP). Methods: Using randomized, parallel, overlapping, self-control designed study, a 100 mg dose of the reference or test tablet was given to 12 CML-CP patients who were resistant or intolerant to Imatinib and Nilotinib in a randomized two-way crossover design, and the plasma concentration of the medicine was assayed by HPLC-MS-MS. The main pharmacokinetic parameters and bioequivalence of the two formulations were evaluated. Results: The major pharmacokinetic parameters were as follows: C_max (209.01±58.69) μg/L and (223.07±79.51) μg/L, T_max (1.1±0.8) h and (1.1±0.8) h, T_1/2 (5.10±1.34) h and (4.39±0.74) h, AUC_0-τ (646.65±185.67) h·μg/L and (695.84±273.40) h·μg/L (all P>0.05); AUC_0-∝ (668.11±186.00) h·μg/L and (712.42±278.08) h·μg/L, MRT (5.32 ± 1.70) h and (4.68 ± 1.53) h (all P>0.05). Conclusion: The two formulations were bioequivalent.

A Universal Assay for Aminopeptidase Activity and Its Application for Dipeptidyl Peptidase-4 Drug Discovery

Aminopeptidases, such as dipeptidyl peptidase-4 (DPP-4, CD26), are potent therapeutic targets for pharmacological interventions because they play key roles in many important pathological pathways. To analyze aminopeptidase activity in vitro (including high-throughput screening [HTS]), in vivo, and ex vivo, we developed a highly sensitive and quantitative bioluminescence-based readout method. We successfully applied this method to screening drugs with potential DPP-4 inhibitory activity. Using this method, we found that cancer drug mitoxantrone possesses significant DPP-4 inhibitory activity both in vitro and in vivo. The pharmacophore of mitoxantrone was further investigated by testing a variety of its structural analogues.

Dasatinib first-line: Multicentric Italian experience outside clinical trials

Dasatinib was approved for the treatment of chronic phase (CP) chronic myeloid leukemia (CML) patients in first line therapy based on the demonstration of efficacy and safety reported in patients enrolled in clinical trials. We describe a multicentric Italian "real-life" experience of dasatinib used as frontline treatment outside clinical trials. One hundred and nine patients (median age 54 years) were treated from January 2012 to December 2013. Increased incidence of high risk patients were detected according to stratification (26% according to Sokal score, 19% according to Euro score and 16% according to EUTOS) when compared to company sponsored studies. Median time from diagnosis to start of dasatinib was 18 days. Ten patients received unscheduled starting dose (6 patients 50mg and 4 patients 80 mg QD), whereas 99 patients started with 100mg QD. At 3 months, 92% of patients achieved a BCR-ABL ratio less than 10%. At 6 months, the rate of CCyR was 91% and the rate of MR3 was 40%, with 8% of the patients reaching MR4.5. Ninety-three patients were evaluable at 12 months: the rate of MR3 was 62%, with MR4.5 being achieved by 19% of the patients. At a median follow-up of 12 months, 27 patients (24.7%) were receiving the drug at reduced dose. Two patients (1.8%) experienced a lymphoid blast crisis and the overall incidence of resistance was 8%. As regards safety, the major side effects recorded were thrombocytopenia, neutropenia and pleural effusions, which occurred in 22%, 10% and 8% of patients, respectively. Present results, achieved in a large cohort of patients treated outside clinical trials, further confirm the efficacy and safety of dasatinib as firstline treatment in CML.

Severe thrombocytopenia after dasatinib treatment in a patient with Philadelphia chromosome-positive chronic myeloid leukemia

Dasatinib, a second-generation tyrosine kinase inhibitor, is used for treating patients with Philadelphia chromosome (Ph) positive leukemia, especially for those who are resistant or intolerant to imatinib. The common adverse effects associated to its use include myelosuppression, nausea, diarrhea, and peripheral edema. This study reports a very rare case of a 60-year-old male who suffered from severe thrombocytopenia after dasatinib administration. The platelet count did not increase even after dasatinib had been discontinued for more than 6 months. Various means had been tried, but the count of platelet did not increase, and the result was not optimistic. This is the first report of so severe thrombocytopenia after dasatinib treatment, and the pathophysiology underlying this reaction remains unknown. We hope that this case will help remind clinicians to pay more attention to the side effect of thrombocytopenia caused by dasatinib in the future.

The role of dasatinib in the management of chronic myeloid leukemia

Dasatinib is a second-generation tyrosine kinase inhibitor (TKI) for chronic, blastic, or accelerated phase chronic myeloid leukemia (CML) patients who are resistant or intolerant to previous treatment. It potently inhibits BCR/ABL and SRC-family kinases (SRC, LCK, HCK, YES, FYN, FGR, BLK, LYN, FRK), as well as c-KIT, PDGFR-a and -b, and ephrin receptor kinase. Various clinical trials have provided evidence that it has more durable complete hematologic and cytogenetic responses, as well as more potency in imatinib-resistant or -intolerant CML, and it has also shown its advantages in newly diagnosed CML compared to imatinib. In this review, we mainly focus on the structure, mechanisms, pharmacokinetics, and pharmacogenetics of dasatinib. We also summarize clinical trials with dasatinib on CML and provide our recommendations for dasatinib in the treatment of CML.

Role of retinoic acid and platelet-derived growth factor receptor cross talk in the regulation of neonatal gonocyte and embryonal carcinoma cell differentiation

Neonatal gonocytes are direct precursors of spermatogonial stem cells, the cell pool that supports spermatogenesis. Although unipotent in vivo, gonocytes express pluripotency genes common with embryonic stem cells. Previously, we found that all-trans retinoic acid (RA) induced the expression of differentiation markers and a truncated form of platelet-derived growth factor receptor (PDGFR)β in rat gonocytes, as well as in F9 mouse embryonal carcinoma cells, an embryonic stem cell-surrogate that expresses somatic lineage markers in response to RA. The present study is focused on identifying the signaling pathways involved in RA-induced gonocyte and F9 cell differentiation. Mitogen-activated protein kinase kinase (MEK) 1/2 activation was required during F9 cell differentiation towards somatic lineage, whereas its inhibition potentiated RA-induced Stra8 expression, suggesting that MEK1/2 acts as a lineage specification switch in F9 cells. In both cell types, RA increased the expression of the spermatogonial/premeiotic marker Stra8, which is in line with F9 cells being at a stage before somatic-germline lineage specification. Inhibiting PDGFR kinase activity reduced RA-induced Stra8 expression. Interestingly, RA increased the expression of PDGFRα variant forms in both cell types. Together, these results suggest a potential cross talk between RA and PDGFR signaling pathways in cell differentiation. RA receptor-α inhibition partially reduced RA effects on Stra8 in gonocytes, indicating that RA acts in part via RA receptor-α. RA-induced gonocyte differentiation was significantly reduced by inhibiting SRC (v-src avian sarcoma [Schmidt-Ruppin A-2] viral oncogene) and JAK2/STAT5 (Janus kinase 2/signal transducer and activator of transcription 5) activities, implying that these signaling molecules play a role in gonocyte differentiation. These results suggest that gonocyte and F9 cell differentiation is regulated via cross talk between RA and PDGFRs using different downstream pathways.