Efficacy and safety of dasatinib versus imatinib in the East Asian subpopulation of the DASISION trial of newly diagnosed chronic myeloid leukemia in chronic phase

Management and Risk Factors for Pleural Effusion in Japanese Patients with Chronic Myeloid Leukemia Treated with First-line Dasatinib in Real-world Clinical Practice

Objective Pleural effusion (PE) is a common adverse event that occurs during dasatinib therapy for chronic myeloid leukemia (CML). However, the pathomechanism of PE and appropriate management of Asian patients with CML have not been elucidated. This study investigated the incidence rate, risk, and appropriate management of PE in Asian patients with CML treated with dasatinib. Methods We retrospectively collected data on patients in the chronic phase of CML who received first-line dasatinib therapy and were registered in the CML-Cooperative Study Group database. Patients We identified 44 cases of PE in a series of 89 patients and analyzed previously reported risk factors and effective management of PE. Results A univariate analysis revealed that age, diabetes mellitus, chronic renal failure, hypertension, the history of cardiovascular events, and dasatinib dose were significantly associated with PE. A multivariate analysis revealed that age ≥65 years old was the only independent risk factor for PE. Dasatinib dose reduction and switching to a tyrosine kinase inhibitor showed a statistically significant difference in effectively reducing PE volume compared to single diuretic use. Conclusion Although further studies are warranted, our observations showed that advanced age is a significant risk factor for PE, and tyrosine kinase inhibitor dose reduction or replacement of dasatinib may be an effective management strategy for PE in Asian CML patients who received first-line treatment with dasatinib in real-world clinical practice.

Real-world efficacy and safety outcomes of imatinib treatment in patients with chronic myeloid leukemia: An Australian experience

Tyrosine kinase inhibitors (TKI) have revolutionized the treatment of chronic myeloid leukemia (CML), but patients still experience treatment-limiting toxicities or therapeutic failure. To investigate the real-world use and outcomes of imatinib in patients with CML in Australia, a retrospective cohort study of patients with CML commencing imatinib (2001-2018) was conducted across two sites. Prescribing patterns, tolerability outcomes, and survival and molecular response were evaluated. 86 patients received 89 imatinib treatments. Dose modifications were frequently observed (12-month rate of 58%). At last follow-up, 62 patients (5-year rate of 55%) had permanently discontinued imatinib treatment, of which 44 switched to another TKI (5-year rate of 46%). Within 3 months of starting imatinib, 43% (95% CI, 32%-53%) of patients experienced imatinib-related grade ≥3 adverse drug reactions (ADRs). Higher comorbidity score, lower body weight, higher imatinib starting dose, and Middle Eastern or North African ancestry were associated with a higher risk of grade ≥3 ADR occurrence on multivariable analysis (MVA). Estimated overall survival and event-free survival rates at 3 years were 97% (95% CI, 92%-100%) and 81% (95% CI, 72%-92%), respectively. Cumulative incidence of major molecular response (MMR) at 3 years was 63% (95% CI, 50%-73%). On MVA, imatinib starting dose, ELTS score, BCR-ABL1 transcript type, pre-existing pulmonary disease, and potential drug-drug interactions were predictive of MMR. In conclusion, imatinib induced deep molecular responses that translated to good survival outcomes in a real-world setting, but was associated with a higher incidence of ADRs, dose modifications and treatment discontinuations than in clinical trials.

Efficacy and Safety of Generic Dasatinib in Patients With Newly Diagnosed Chronic Myeloid Leukemia in Chronic Phase: A Multicenter Prospective Study in China

BACKGROUND

Brand-name dasatinib was approved for newly diagnosed chronic myeloid leukemia-chronic phase (CML-CP) patients due to its deeper and faster molecular response than imatinib. Generics, as the alternative, low-cost forms, are much in demand. This study aimed to evaluate the efficacy and safety of generic dasatinib (Yinishu) as a first-line treatment in CML-CP.

MATERIALS AND METHODS

This was a prospective, multicenter, single-arm study from May 2016 to October 2018 with a 2-year follow-up analysis. All patients were given 100 mg/d (initial dose) of the generic dasatinib once a day. The primary endpoint was the major molecular response (MMR) calculated based on the BCR-ABL1 gene mutation rate of ≤ .1% at 12 months.

RESULTS

Among 55 patients in CP observed for at least 3 months, 80.4% achieved MMR at 12 months. The cumulative MR4.5 was 58.2% by 24 months. Responses occurred rapidly, with 69.1% of patients achieving complete cytogenetic response (CCyR) by 3 months and 70.9% achieving CCyR by 6 months. The estimated 2-year PFS and OS were both 96%, with a median follow-up time of 24 months. Grade 3 neutropenia occurred in 8.5% of patients, and thrombocytopenia occurred in 11.9% of patients. Nonhematologic toxicity was usually mild and manageable. Pleural effusion occurred in 20.3% of patients, and only 1 patient (1.7%) had a grade 3 pleural effusion. No grade 4 adverse events were observed.

CONCLUSION

Generic dasatinib is an effective option for newly diagnosed CML-CP patients, producing an MMR early in a greater number of patients during their therapy.

Simultaneous quantification of dasatinib, nilotinib, bosutinib, and ponatinib using high-performance liquid chromatography-Photodiode array detection

Background

Dasatinib, nilotinib, and bosutinib, second‐generation tyrosine kinase inhibitors (TKIs), and ponatinib, a third‐generation TKI, are approved pharmaceuticals used in the treatment of chronic myeloid leukemia (CML). Although liquid chromatography‐tandem mass spectrometry assays for simultaneous quantification of the four TKIs in human serum have been reported in the literature, a high‐performance liquid chromatography (HPLC) assay that simultaneously quantifies these compounds has not yet been developed. This study aims to establish and validate an efficient HPLC analytical method using a photodiode array (PDA) detector for the simultaneous quantification of the four TKIs.

Methods

Calibration standards were prepared by serial dilution of serum samples containing the four TKIs, followed by solid‐phase extraction. The four TKIs were eluted in order within 10 min using a binary HPLC gradient system.

Results

The calibration ranges were 2–500 ng/ml for dasatinib, 100–5000 ng/ml for nilotinib, and 10–500 ng/ml for bosutinib and ponatinib. Intra‐day and inter‐day precision and accuracy values were found to be in accordance with the U.S. Food and Drug Administration guidelines. The recovery rates were 92.9%–96.0%, 80.7%–86.1%, 91.6%–99.0%, and 86.4%–92.6% for dasatinib, nilotinib, bosutinib, and ponatinib, respectively.

Conclusion

To the best of our knowledge, this is the first report of an HPLC‐PDA analytical method that allows efficient simultaneous quantification of the four TKIs in the serum of patients with CML. We believe that the method developed herein can improve the efficiency of therapeutic drug monitoring in patients with CML in clinical practice.

Safety profile of bosutinib in Japanese versus non-Japanese patients with chronic myeloid leukemia: a pooled analysis

Bosutinib has been investigated in multiple clinical trials globally, including Japan, for treatment of chronic myeloid leukemia (CML). A pooled analysis of seven Pfizer-sponsored clinical trials evaluated the safety of bosutinib in Japanese (n = 138) vs non-Japanese (n = 1210) patients with CML. First-line bosutinib was administered in 54.3% vs 41.4% of patients, and second-line or later bosutinib in the remainder. Median treatment duration was 1.4 vs 2.3 years, and median relative dose intensity 78.1% vs 90.0%. Any-grade treatment-emergent adverse events (TEAEs) occurred in 100.0% vs 98.9% (grade ≥ 3: 81.9% vs 75.2%). In both groups, the most common TEAEs relevant to bosutinib were gastrointestinal (92.8% vs 84.7%), liver function (72.5% vs 34.8%), rash (63.8% vs 37.4%), and myelosuppression (55.1% vs 50.7%). TEAEs led to dose reduction in 65.2% vs 50.6%, dose interruption in 78.3% vs 68.8%, and permanent treatment discontinuation in 30.4% vs 25.4% of patients. The safety profile of bosutinib in Japanese patients was generally consistent with that in non-Japanese patients, despite a higher incidence of gastrointestinal, liver function, and rash events. TEAEs were largely manageable with dose modifications and supportive care in both groups. These data may help optimize TEAE management and outcomes in Japanese patients receiving bosutinib for CML. Trial registration ClinicalTrials.gov: NCT02130557, NCT03128411, NCT00574873, NCT00261846, NCT01903733, NCT00811070, NCT02228382.

Comparison of Dasatinib- and Imatinib-Related Cardiotoxic Adverse Events in Japanese Patients With Chronic Myeloid Leukemia and Gastrointestinal Stromal Tumor

Background: Despite the beneficial effects of BCR-ABL1 tyrosine kinase inhibitors (TKIs) in the treatment of chronic myeloid leukemia (CML), they may also cause adverse events (AEs), especially cardiovascular toxicity. The incidence of TKI-induced AEs may vary among ethnic groups, and there is little specific information for Japanese patients.

Methods and Results: Sixty-nine consecutive patients who were started on treatment with dasatinib (n=25) or imatinib (n=44) for CML or gastrointestinal stromal tumor (GIST) between December 2008 and December 2019 were retrospectively recruited to the study. We determined the prevalence of AEs through October 2020 and compared the incidence of AEs between the 2 drugs. Baseline characteristics were comparable between the 2 groups. However, compared with the imatinib-treated group, the dasatinib-treated group had a higher incidence of congestive heart failure (CHF; 20.0% vs. 2.3%; P=0.04), pleural effusion (48% vs. 20.5%; P=0.03), pericardial effusion (24% vs. 4.6%; P=0.02), QT prolongation (4 vs. 0 patients; P=0.02), and pulmonary hypertension (3 vs. 0 patients; P=0.04). In the dasatinib-treated group, CHF tended to be associated with tricuspid valve regurgitation pressure gradient, and pleural effusion was observed in all patients. All-cause mortality and other cardiovascular events did not differ significantly between the 2 groups.

Conclusions: Cardiotoxic AEs occurred more frequently in Japanese patients with CML and GIST treated with dasatinib than imatinib.

The effect of imatinib and nilotinib on blood calcium and blood potassium levels in chronic myeloid leukemia patients: a literature review

Imatinib and nilotinib are first-line treatments for chronic myeloid leukemia (CML) patients, which act specifically against target cells. However, these drugs may cause side effects, such as electrolyte disturbances. This literature review aimed to provide a comparison of the effects of imatinib and nilotinib on blood potassium and calcium levels. It also summarized their hypothetical mechanism. A comprehensive electronic search of the different databases was conducted using ‘chronic myeloid leukemia’, ‘tyrosine kinase inhibitors’, ‘imatinib’, ‘nilotinib’, ‘potassium’, ‘calcium’, ‘electrolytes’ as keywords. This review used PubMed- MEDLINE, Cochrane Library, and Google Scholar as the source databases. Sixteen articles published from 2006 to 2020 were reviewed. Changes in blood potassium levels range from increased to decreased levels, while changes in blood calcium levels range from the lower normal values to below normal values (hypocalcemia). Tyrosine kinase inhibitors (TKIs), including imatinib and nilotinib, have a non-specific target, namely plateletderived growth factor receptor (PDGFR), which indirectly affects blood potassium and calcium levels in CML patients. The clinical manifestations of these changes vary from being visible only in laboratory tests to displaying a variety of clinical signs and symptoms.

Efficacy and safety of bosutinib versus imatinib for newly diagnosed chronic myeloid leukemia in the Asian subpopulation of the phase 3 BFORE trial

Bosutinib is approved in the United States, Europe, Japan, and other countries for treatment of newly diagnosed chronic phase (CP) chronic myeloid leukemia (CML), and CML resistant/intolerant to prior therapy. In the phase 3 BFORE trial (Clinicaltrials.gov, NCT02130557), patients were randomized 1:1 to first-line bosutinib or imatinib 400 mg once daily. We examined efficacy, safety, and patient-reported outcomes of bosutinib vs imatinib and pharmacokinetics of bosutinib in the Asian (n = 33 vs 34) and non-Asian (n = 235 vs 234) subpopulations of BFORE followed for at least 24 months. At the data cutoff date, 72.7 vs 66.7% of Asian and 70.6 vs 66.4% of non-Asian patients remained on treatment. The major molecular response rate at 24 months favored bosutinib vs imatinib among Asian (63.6 vs 38.2%) and non-Asian (60.9 vs 52.6%) patients, as did the complete cytogenetic response rate by 24 months (86.7 vs 76.7%, 81.5 vs 76.3%). Treatment-emergent adverse events in both subpopulations were consistent with the primary BFORE results. Trough bosutinib concentration levels tended to be higher in Asian patients. Health-related quality of life was maintained after 12 months of bosutinib in both subpopulations. These results support bosutinib as a first-line treatment option in Asian patients with CP CML.

Chronic myeloid leukemia-from the Philadelphia chromosome to specific target drugs: A literature review

Chronic myeloid leukemia (CML) is a myeloproliferative neoplasm and was the first neoplastic disease associated with a well-defined genotypic anomaly - the presence of the Philadelphia chromosome. The advances in cytogenetic and molecular assays are of great importance to the diagnosis, prognosis, treatment, and monitoring of CML. The discovery of the breakpoint cluster region (BCR)-Abelson murine leukemia (ABL) 1 fusion oncogene has revolutionized the treatment of CML patients by allowing the development of targeted drugs that inhibit the tyrosine kinase activity of the BCR-ABL oncoprotein. Tyrosine kinase inhibitors (known as TKIs) are the standard therapy for CML and greatly increase the survival rates, despite adverse effects and the odds of residual disease after discontinuation of treatment. As therapeutic alternatives, the subsequent TKIs lead to faster and deeper molecular remissions; however, with the emergence of resistance to these drugs, immunotherapy appears as an alternative, which may have a cure potential in these patients. Against this background, this article aims at providing an overview on CML clinical management and a summary on the main targeted drugs available in that context.

Appropriate Starting Dose of Dasatinib Based on Analyses of Dose-Limiting Toxicities and Molecular Responses in Asian Patients With Chronic Myeloid Leukemia

BACKGROUND

Dasatinib is administered at a fixed starting dosage of 100 mg once daily regardless of patient-specific factors. However, such fixed dosing may not be optimal for the treatment of Asian patients with chronic myeloid leukemia in chronic phase (CP-CML).

PATIENTS AND METHODS

The dose-limiting toxicities (DLTs) and molecular responses (MRs) of dasatinib therapy were evaluated using clinical data obtained from 102 patients newly diagnosed with CP-CML at 17 hospitals in South Korea.

RESULTS

By 36 months after the initiation of a fixed dose regimen of dasatinib 100 mg once daily as the first-line therapy, 55.9% of patients experienced at least one type of DLT. The 3 most frequent DLTs were thrombocytopenia (45.5%), pericardial or pleural effusion (30.9%), and anemia (7.3%). Patients with higher dasatinib dose adjusted for body weight (Dose/BW) had a greater rate of DLT occurrence (logit [P] = 1.58 × [Dose/BW] - 2.27, P = .03). As median Dose/BW increased from 1.23 to 2.00 mg/kg, the rate of DLT occurrence increased from 43.5% to 66.7% (P = .03). However, Dose/BW did not affect the achievement rate of major MR (60.9% to 69.6%, P = .92).

CONCLUSION

The starting dosage of dasatinib may need to be reduced (eg, 80 mg once daily or lower) for Asian patients with CP-CML, especially with lighter BW, to alleviate the risk of DLT occurrence without compromising the achievement of MR.

Influence of proton pump inhibitors and H2-receptor antagonists on the efficacy and safety of dasatinib in chronic myeloid leukemia patients

We evaluated the effect of proton pump inhibitors (PPIs) and H2-receptor antagonists (H2RAs) on the efficacy and safety of dasatinib for chronic-phase chronic myeloid leukemia (CP-CML). Retrospective analyses were performed for patients with CP-CML who received dasatinib at seven hospitals between April 2009 and December 2016. Seventy-three patients were identified, 16 of whom received PPIs or H2RAs concurrently with dasatinib. Major molecular response at 12 months was observed in 13 of 13 patients (100%) with concurrent PPIs or H2RAs (combination group), and in 23 of 51 patients (45.1%) who received only dasatinib (dasatinib-alone group; P < 0.001). Deep molecular response at 12 months was observed in four of six patients (66.7%) in the combination group, and seven of 38 patients (18.4%) in the dasatinib-alone group (P = 0.027). Dasatinib chemotherapy was stopped after 18 months for 25 patients (43.9%) from the dasatinib-alone group, but for none from the combination group. Combination treatment with PPIs or H2RAs did not reduce the efficacy of dasatinib. PPIs and H2RAs reduce the incidence of dasatinib discontinuation due to adverse events and increase the efficacy of dasatinib chemotherapy for patients.

Phase III Clinical Trial (RERISE study) Results of Efficacy and Safety of Radotinib Compared with Imatinib in Newly Diagnosed Chronic Phase Chronic Myeloid Leukemia

Purpose: Radotinib is a second-generation BCR-ABL1 tyrosine kinase inhibitor (TKI) approved in Korea for chronic phase chronic myeloid leukemia (CML-CP) in patients newly diagnosed or with insufficient response to other TKIs. This study was conducted to evaluate the efficacy and safety of radotinib as first-line therapy for CML-CP.Experimental Design: This multinational, open-label study assigned patients (1:1:1) to one of two twice-daily radotinib doses, or imatinib daily. The primary endpoint was major molecular response (MMR) by 12 months.Results: Two hundred forty-one patients were randomized to receive radotinib 300 mg (n = 79) or 400 mg twice-daily (n = 81), or imatinib 400 mg daily (n = 81). MMR rates by 12 months were higher in patients receiving radotinib 300 mg (52%) or radotinib 400 mg twice-daily (46%) versus imatinib (30%; P = 0.0044 and P = 0.0342, respectively). Complete cytogenetic response (CCyR) rates by 12 months were higher for radotinib 300 mg (91%) versus imatinib (77%; P = 0.0120). Early molecular response at 3 months occurred in 86% and 87% of patients receiving radotinib 300 mg and radotinib 400 mg, respectively, and 71% of those receiving imatinib. By 12 months, no patients had progression to accelerated phase or blast crisis. Most adverse events were manageable with dose reduction.Conclusions: Radotinib demonstrated superiority over imatinib in CCyR and MMR in patients newly diagnosed with Philadelphia chromosome-positive CML-CP. This trial was registered at www.clinicaltrials.gov as NCT01511289 Clin Cancer Res; 23(23); 7180-8. ©2017 AACR.

Dasatinib: A Review in Chronic Myeloid Leukaemia and Ph+ Acute Lymphoblastic Leukaemia

Dasatinib (Sprycel^®) is an orally administered, small molecule inhibitor of multiple tyrosine kinases. In the phase 3 DASISION trial, dasatinib 100 mg once daily resulted in deeper and faster cytogenetic and molecular responses than imatinib 400 mg once daily in patients with newly diagnosed, chronic-phase chronic myeloid leukaemia (CML), although there was no significant between-group difference in progression-free survival (PFS) or overall survival (OS) in the longer term. In the phase 3 CA180-034 trial, a regimen of dasatinib 100 mg once daily provided the most favourable benefit-risk profile in patients with imatinib-resistant or -intolerant chronic-phase CML. In the phase 3 CA180-035 trial, a regimen of dasatinib 140 mg once daily demonstrated efficacy in patients with accelerated- or blast-phase CML or Ph+ acute lymphoblastic leukaemia (ALL) resistant or intolerant to imatinib. Dasatinib had an acceptable tolerability profile. In conclusion, dasatinib is an important option for the treatment of patients with newly diagnosed chronic-phase CML and for imatinib-resistant or -intolerant patients with chronic- or advanced-phase CML or Ph+ ALL.

Dasatinib versus imatinib in Japanese patients with newly diagnosed chronic phase chronic myeloid leukemia: a subanalysis of the DASISION 5-year final report

The international phase III DASISION trial demonstrated improved efficacy of dasatinib versus imatinib in treatment-naive patients with chronic myeloid leukemia in the chronic phase (CML-CP). We report efficacy and safety outcomes in a Japanese population from the final, 5-year follow-up of DASISION. At the end of the study, 77% (20/26) of dasatinib-treated and 61% (14/23) of imatinib-treated patients remained on initial therapy. Improved responses were observed in Japanese patients who received dasatinib versus imatinib (complete cytogenetic response: 96 vs 87%; major molecular response: 88 vs 74%; BCR-ABL1 ≤0.0032% International Scale [MR^4.5]: 58 vs 52%). In patients who achieved BCR-ABL1 ≤10% at 3 months, 5-year progression-free survival and overall survival rates were high with dasatinib (96 and 96%) and imatinib (88 and 100%). The majority of adverse events were grade 1/2 in Japanese patients. Pleural effusion occurred more frequently in dasatinib-treated Japanese patients versus all patients (42 vs 28%), with no treatment discontinuations. Overall, in Japanese patients, dasatinib maintained its safety profile and had higher or comparable response and survival outcomes compared with imatinib or with all patients in DASISION. These findings demonstrate the long-term efficacy and tolerability of dasatinib and support frontline treatment of Japanese patients with CML-CP with dasatinib.

Is Adherence to Imatinib Mesylate Treatment Among Patients with Chronic Myeloid Leukemia Associated with Better Clinical Outcomes in Qatar?

BACKGROUND

Despite the revolutionary success of introducing tyrosine kinase inhibitors (TKIs), such as imatinib mesylate (IM), for treating chronic myeloid leukemia (CML), a substantial proportion of patients' treatments fail.

AIM

This study investigates the correlation between patient adherence and failure of TKIs' treatment in a follow-up study.

METHODS

This is a follow-up study of a new cohort of CML patients. Adherence to IM is assessed using the Medication Event Monitoring System (MEMS 6 TrackCap, AARDEX Ltd). The 9-item Morisky Medication Adherence Scale, medication possession ratio (MPR) calculation, and the electronic medical records are used for identifying potential factors that influence adherence. Clinical outcomes are assessed according to the European Leukemia Net 2013 guidelines via reverse transcriptase quantitative polymerase chain reaction measurement of the level of BCR-ABL1 transcripts in peripheral blood. Response is classified at the hematological, cytogenetic, and molecular levels into optimal, suboptimal, or failure.

RESULTS

A total of 36 CML patients (5 citizens and 31 noncitizen residents) consented to participate in the study. The overall mean MEMS score was 89. Of the 36 patients, 22 (61%) were classified as adherent (mean: 95) and 14 (39%) were classified as nonadherent (mean: 80.2). Adherent patients were significantly more likely to obtain optimal response (95%) compared to the nonadherent group (14.3%; P < 0.0001). The rate of poor adherence was as high as 39% using MEMS, which correlates with 37% treatment failure rate. The survey results show that 97% of patients increased the IM dose by themselves when they felt unwell and 31% of them took the missing IM dose when they remembered. Other factors known to influence adherence show that half of patients developed one or more side effects, 65% of patients experienced lack of funds, 13% of patients declared unavailability of the drug in the NCCCR pharmacy, and 72% of patients believed that IM would cure the disease. The MPR results reveal that 16% of patients had poor access to treatment through the hospital pharmacy.

DISCUSSION AND CONCLUSION

This is the first prospective study to evaluate CML patients' adherence and response to IM in Qatar. The high rate of treatment failure observed in Qatar is explained by poor adherence. An economic factor (unaffordable drug prices) is one of the main causes of nonadherence and efforts should be made locally to improve access to medication for cancer diseases. Other risk factors associated with poor adherence could be improved by close monitoring and dose adjustment. Monitoring risk factors for poor adherence and patient education that include direct communication between the health-care teams, doctors, nurses, pharmacists, and patients are essential components for maximizing the benefits of TKI therapy and could rectify this problem. The preliminary results show that patients' response to treatment may be directly linked to patients' adherence to treatment. However, further in-depth and specific analysis may be necessary in a larger cohort.

Association of pleural effusion with an early molecular response in patients with newly diagnosed chronic-phase chronic myeloid leukemia receiving dasatinib: Results of a D-First study

Despite the efficacy and safety of dasatinib treatment for chronic-phase chronic myeloid leukemia (CML-CP), adverse effects such as pleural effusion (PE) are still a serious concern. We determined the clinical significance of PE incidence using patient data derived from the D-First clinical study. In the present study, chest radiography and quantification of specific lymphocyte subsets were performed routinely after initiation of dasatinib treatment. Among 52 patients with newly diagnosed CML-CP, 17 (33%) developed PE within 18 months after initial dasatinib administration, but all cases were moderate (Grade 1, 10 patients; Grade 2, 7 patients). CD56+ lymphocyte counts at 1 month correlated significantly with the incidence of PE, whereas lymphocytosis did not. The major molecular response (MMR) rate at 3 months (although not at later times) was significantly higher in PE-positive patients than PE-negative patients (59% versus 24%, respectively; P=0.013). Deep molecular response rates did not differ significantly between the PE groups at any time point during the observation period. Our results suggest that an immune-mediated mechanism involving natural killer cells underlies the development of PE in patients receiving dasatinib for 18 months. This mechanism likely promotes transient tumor regression in patients newly diagnosed with CML-CP.

Therapeutic drug monitoring of imatinib, nilotinib, and dasatinib for patients with chronic myeloid leukemia

Imatinib, nilotinib, and dasatinib are tyrosine kinase inhibitors (TKIs) that have become first-line treatments for Philadelphia chromosome-positive chronic myeloid leukemia (CML). According to European LeukemiaNet recommendations, the clinical response of CML patients receiving TKI therapy should be evaluated after 3, 6, and 12 months. For patients not achieving a satisfactory response within 3 months, the mean plasma concentration for the three months of TKI administration must be considered. In TKI therapy for CML patients, therapeutic drug monitoring is a new strategy for dosage optimization to obtain a faster and more effective clinical response. The imatinib plasma trough concentration (C₀) should be set above 1000 ng/mL to obtain a response and below 3000 ng/mL to avoid serious adverse events such as neutropenia. For patients with a UGT1A1*6/*6, *6/*28, or *28/*28 genotype initially administered 300-400 mg/d, a target nilotinib C₀ of 500 ng/mL is recommended to prevent elevation of bilirubin levels, whereas for patients with the UGT1A1*1 allele initially administered 600 mg/d, a target nilotinib C₀ of 800 ng/mL is recommended. For dasatinib, it is recommended that a higher Cmax or C₂ (above 50 ng/mL) to obtain a clinical response and a lower C₀ (less than 2.5 ng/mL) to avoid pleural effusion be maintained by once daily administration of dasatinib. Although at present clinicians consider the next pharmacotherapy from clinical responses (efficacy/toxicity) obtained by a fixed dosage of TKI, the TKI dosage should be adjusted based on target plasma concentrations to maximize the efficacy and to minimize the incidence of adverse events.

Hsp90 Inhibitors for the Treatment of Chronic Myeloid Leukemia

Chronic myeloid leukemia (CML) is a hematological malignancy that arises due to reciprocal translocation of 3' sequences from c-Abelson (ABL) protooncogene of chromosome 9 with 5' sequence of truncated break point cluster region (BCR) on chromosome 22. BCR-ABL is a functional oncoprotein p210 that exhibits constitutively activated tyrosine kinase causing genomic alteration of hematopoietic stem cells. BCR-ABL specific tyrosine kinase inhibitors (TKIs) successfully block CML progression. However, drug resistance owing to BCR-ABL mutations and overexpression is still an issue. Heat-shock proteins (Hsps) function as molecular chaperones facilitating proper folding of nascent polypeptides. Their increased expression under stressful conditions protects cells by stabilizing unfolded or misfolded peptides. Hsp90 is the major mammalian protein and is required by BCR-ABL for stabilization and maturation. Hsp90 inhibitors destabilize the binding of BCR-ABL protein thus leading to the formation of heteroprotein complex that is eventually degraded by the ubiquitin-proteasome pathway. Results of many novel Hsp90 inhibitors that have entered into various clinical trials are encouraging. The present review targets the current development in the CML treatment by availing Hsp90 specific inhibitors.

Routine therapeutic drug monitoring of tyrosine kinase inhibitors by HPLC-UV or LC-MS/MS methods

Analytical methods using high performance liquid chromatography coupled to ultraviolet detection (HPLC-UV) or liquid chromatography-tandem mass spectrometry (LC-MS/MS) have been reported for the quantification of oral tyrosine kinase inhibitors (TKIs) such as imatinib, nilotinib, and dasatinib in biological fluids. An LC-MS/MS method can simultaneously assay multiple TKIs and their metabolites with high sensitivity and selectivity for low plasma concentrations less than 1 ng/mL. For quantification of imatinib, nilotinib, and dasatinib, a limit of quantification (LOQ) of less than 10 ng/mL, 10 ng/mL, and 0.1 ng/mL, respectively, in the clinical setting is necessary. Because simpler and more cost-efficient methodology is desired for clinical analysis, plasma concentrations of imatinib and nilotinib (target trough concentrations of 1000 ng/mL and 800 ng/mL, respectively) could be assayed by an HPLC-UV method after comparison with results obtained from the standard LC-MS/MS method. However, in the quantification of dasatinib, the LC-MS/MS method that has high sensitivity and selectivity and is free from interference by endogenous impurities is superior to the HPLC-UV method. Highly precise analytical methods are needed for individualized treatment via dose adjustment of oral anticancer drugs, in particular those with low target plasma concentrations less than 10 ng/mL.

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.