What Is the Optimal Dose and Schedule for Dasatinib in Chronic Myeloid Leukemia: Two Case Reports and Review of the Literature

Long-term follow-up of efficacy and safety in elderly patients with chronic myeloid leukemia treated with intermittent low dose dasatinib therapy

Intermittent low dose dasatinib therapy brought about a beneficial effect in elderly patients with chronic-phase chronic myeloid leukemia (CML-CP) without inducing severe adverse events (AEs). An 85-year-old male patient, who received twice-weekly, thrice-weekly, or four-times-weekly administration of 20 mg/day dasatinib after once-weekly administration, achieved a major molecular response two years after the start of dasatinib treatment and later sometimes achieved a deep molecular response, maintaining the efficacy for 11 years. The mean daily dose ranged from 5.7 mg to 11.4 mg. Furthermore, a 79-year-old male patient, who received thrice-weekly or every other day administration of 20 mg/day dasatinib after once-weekly administration, achieved a deep molecular response at four and half years after the start of dasatinib treatment. The mean daily dose is 8.6 mg. Intermittent low dose dasatinib therapy appears to be feasible in elderly patients with CML-CP. The goal of treatment in elderly patients with CML-CP appears to be different from that in younger patients, since they often suffer from serious AEs in the case of standard dose tyrosine kinase inhibitor therapy, followed by the dose reduction or cessation of treatment.

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.

Evaluation of Medication Adherence and Pharmacokinetics of Dasatinib for Earlier Molecular Response in Japanese Patients With Newly Diagnosed Chronic Myeloid Leukemia: A Pilot Study

BACKGROUND

Tyrosine kinase inhibitors markedly improve the survival for patients with chronic myeloid leukemia (CML). However, a decrease in adherence leads to undesired therapeutic outcomes. In this study, the relationships among adherence, pharmacokinetics, response, and adverse effects for dasatinib treatment were prospectively investigated.

METHODS

This study was a prospective cohort study of patients with newly diagnosed CML at 4 general hospitals and 1 university hospital. Patients started to receive dasatinib 100 mg once daily. A Medication Event Monitoring System was used to assess medication adherence and the medication possession ratio during the 12 months. Plasma concentrations of dasatinib were measured using liquid chromatograph-tandem mass spectrometry (LC-MS/MS), and therapy responses were assessed at 3, 6, and 12 months after treatment.

RESULTS

Ten patients were included. An extremely high medication adherence for dasatinib was observed; the median medication possession ratio was 99.4%. All 9 CML patients with breakpoints in the major BCR-ABL achieved major molecular response (MMR; major BCR-ABL transcript level below 0.1% on the International Scale) within 12 months, and 5 achieved MMR within 6 months. The receiver operating characteristic curve analysis revealed that the cutoff value for the dasatinib area under the concentration-time curve was 336.1 ng × h/mL (accuracy 88.9%, sensitivity 80.0%, specificity 100%, and receiver operating characteristic curve-area under the concentration-time curve 0.800) for achieving MMR within 6 months. Two patients had interrupted dasatinib treatment because of pleural effusion and diarrhea with intestinal edema, respectively. These edematous adverse events developed after plasma dasatinib Cmin surpassed 3.0 ng/mL.

CONCLUSIONS

A Medication Event Monitoring System was applied for the direct evaluation of oral dasatinib adherence for the first time, and the clinical effect of dasatinib was investigated under the strict monitoring of patient adherence. Although this study had a small sample size, the plasma concentration monitoring of dasatinib is considered to be useful to predict an earlier molecular response with fewer edematous adverse events.

3D culture enhances chemoresistance of ALL Jurkat cell line by increasing DDR1 expression

Three dimensional (3D) culture has gradually become a research hotspot in the field of drug screening, stem cell research, and tissue engineering due to its more physiological-like morphology and function. In this study, we compared the differences of cell proliferation, population, protein expression and chemoresistance profiles between two dimensional (2D) and 3D culture of acute lymphoblastic leukemia (ALL) Jurkat cell line. Polycaprolactone (PCL) is used for 3D culture owing to its biochemical properties and compatibility. Culturing of ALL Jurkat cell line in collagen type I coated polycaprolactone scaffold for 168 h increased cell proliferation, attachment, as well as the drug resistance to cytarabine (Ara-C) and daunorubicin (DNR) without changing the original CD2⁺CD3⁺CD4^+dimCD8⁻CD34⁻CD45^+dim phenotype, compared to uncoated PCL scaffold and tissue culture plate systems. Molecularly, increased chemoresistance is associated with the upregulation of discoidin domain receptor 1 (DDR1) and transcription factor STAT3. Inhibition of DDR1 activity by DDR1-specific inhibitor DDR-IN-1 accelerated cell death in the presence of Ara-C, DNR or their combination. These results demonstrated that 3D culture enhances chemoresistance of ALL Jurkat cell line by increasing DDR1 expression. Importantly, the cell adhesion-mediated drug resistance induced by DDR1 in the scaffold was similar to the clinical situation, indicating the 3D culture of cancer cells recapitulate the in vivo tumor environment and this platform can be used as a promising pre-clinic drug-screen system.

A systematic review of non-standard dosing of oral anticancer therapies

Background

The use of oral systemic anticancer therapies (SACT) has increased and led to improved cancer survival outcomes, particularly with the introduction of small molecule targeted agents and immunomodulators. Oral targeted SACT are, however, associated with toxicities, which might result in reduced quality of life and non-adherence. To reduce treatment-related toxicity, the practice of non-standard dosing is increasing; however guidance to govern this practice is limited. A systematic review was conducted to identify evidence of, and outcomes from, non-standard dosing of oral SACT in oncology and malignant haematology.

Methods

A comprehensive search of 78 oral SACT was conducted in the following databases: MEDLINE®, EMBASE®, Cochrane Library©, and Cumulative Index to Nursing and Allied Health Literature (CINAHL©). Studies were selected based on predefined inclusion/exclusion criteria, and were critically appraised. Extracted data were tabulated to summarise key findings. Due to diversity of study designs and heterogeneity of reported outcomes, studies were categorised and evidence was synthesised in three main themes: dose interruption; dose reduction; and other dosing strategies.

Results

Thirty-four studies were eligible for inclusion: four clinical trials, fifteen cohort studies and fifteen case reports. Evidence for non-standard dosing was reported for eleven oral SACT. Dose interruptions were the most commonly reported strategy (14 studies); nine studies reported dose reductions; and eleven reported other dosing strategies. Eight retrospective cohort studies reported dose interruption of sunitinib in renal cell carcinoma and showed either similar or improved responses and survival outcomes, and fewer or equivalent high grade toxicities, compared to the standard schedule. Four cohort studies retrospectively evaluated dose reductions of imatinib, gefitinib or erlotinib, for chronic myeloid leukaemia and non-small cell lung cancer, respectively. Other dosing strategies included alternate-day dosing. The quality of the evidence was limited by the small sample size in many studies, retrospective study designs, and lack of reported toxicity and/or QoL outcomes.

Conclusions

This review identified limited evidence to support current non-standard dosing strategies, but some of findings, e.g. dose interruption of sunitinib, warrant further investigation in large-scale prospective clinical trials.

Electronic supplementary material

The online version of this article (10.1186/s12885-018-5066-2) contains supplementary material, which is available to authorized users.

Dasatinib dose management for the treatment of chronic myeloid leukemia

Chronic myeloid leukemia (CML) has evolved into a chronic disease that is managed with tyrosine kinase inhibitor therapy. Now that long-term survival has been achieved in patients with CML, the focus of treatment has shifted to dose optimization, with the goal of maintaining response while improving quality of life. In this review, the authors discuss optimizing the dose of the second-generation tyrosine kinase inhibitor dasatinib. Once-daily dosing regimens for dasatinib in the first and later lines of treatment were established through long-term (5-year and 7-year) trials. Recently published data have indicated that further dose optimization may maintain efficacy while minimizing adverse events. Results obtained from dose optimization and discontinuation trials currently in progress will help practitioners determine the best dose and duration of dasatinib for patients with CML, because treatment decisions will be made through continued discussions between physicians and patients. Cancer 2018;124:1660-72. © 2018 The Authors. Cancer published by Wiley Periodicals, Inc. on behalf of American Cancer Society. This is an open access article under the terms of the Creative Commons Attribution-NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.

Theory and practice of clinical pharmacodynamics in oncology drug development

The clinical development of molecularly targeted cancer therapies is enhanced by proof of mechanism of action as well as proof of concept, which relate molecular pharmacodynamics to efficacy via changes in cancer cell biology and physiology resulting from drug action on its intended target. Here, we present an introduction to the field of clinical pharmacodynamics, its medical and laboratory aspects, and its practical incorporation into clinical trials. We also describe key success factors that are useful for judging the quality of clinical pharmacodynamic studies, including biopsy quality and suitability, specimen handling, assay fitness-for-purpose, and reagent quality control. This introduction provides not only context for the following articles in this issue, but also an appreciation of the role of well-conducted clinical pharmacodynamic studies in oncology drug development.