The Efficacy of Reduced-dose Dasatinib as a Subsequent Therapy in Patients with Chronic Myeloid Leukemia in the Chronic Phase: The LD-CML Study of the Kanto CML Study Group

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.

Population Pharmacokinetics and Pharmacogenetics Analyses of Dasatinib in Chinese Patients with Chronic Myeloid Leukemia

AIMS

Dasatinib, a second-generation tyrosine kinase inhibitor of BCR-ABL 1, used for first-line treatment of Philadelphia chromosome-positive chronic myeloid leukemia (CML), exhibits high pharmacokinetic (PK) variability. However, its PK data in Chinese patients with CML remains rarely reported to date. Thus, we developed a population pharmacokinetic (PPK) model of dasatinib in Chinese patients and identified the covariate that could explain the individual variability of PK for optimal individual administration.

METHODS

PPK modeling for dasatinib was performed based on 754 plasma concentrations obtained from 140 CML patients and analysis of various genetic and physicochemical parameters. Modeling was performed with nonlinear mixed-effects (NLME) using Phoenix NLME. The finally developed model was evaluated using internal and external validation. Monte Carlo simulations were used to predict drug exposures at a steady state for various dosages.

RESULTS

The PK of dasatinib were well described by a two-compartment with a log-additive residual error model. Patients in the current study had a relatively low estimate of CL/F (126 L/h). A significant association was found between the covariate of age and CL/F of dasatinib, which was incorporated into the final model. None of the genetic factors was confirmed as a significant covariate for dasatinib. The results of external validation with 140 samples from 36 patients were acceptable. Simulation results showed significantly higher exposures in elderly patients.

CONCLUSIONS

This study's findings suggested that low-dose dasatinib would be better suited for Chinese patients, and the dosage can be appropriately reduced according to the increase of age, especially for the elderly.

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.

On the road to treatment-free remission in chronic myeloid leukemia: what about 'the others'?

INTRODUCTION

The treatment of chronic myeloid leukemia (CML) has been drastically changed by the approval of tyrosine kinase inhibitors (TKIs). CML is now managed as a chronic disease requiring both long-term treatment and close molecular monitoring in the majority of patients.

AREAS COVERED

Evidence suggests that in a substantial number of patients who have achieved a stable deep molecular response (DMR), TKI treatment can be safely discontinued without loss of response. Therefore, treatment-free remission (TFR), through the achievement of a DMR, is increasingly regarded as a feasible treatment goal in about 20% to 40% CML patients. Nevertheless, a proportion of patients with chronic-phase CML treated with TKIs remain in stable MMR and do not achieve a DMR.

EXPERT OPINION

We provide prospective views on how it is possible to optimize treatment for patients in stable MMR but not in DMR in order to finalize the therapeutic strategy.

Is There a Role for Dose Modification of TKI Therapy in CML?

Purpose of Review

For patients with chronic phase chronic myeloid leukemia (CP-CML), there is an increasing focus on personalization of therapy with dose modifications of tyrosine kinase inhibitors (TKIs) to reduce side effects and maintain efficacy. Dose reductions are also being considered in clinical trials prior to treatment-free remission (TFR) attempts.

Recent Findings

Recent retrospective analyses of large clinical trials show that dose modification/reduction is safe. Efficacy is generally maintained and side effects are improved. Clinical trials such as DESTINY have demonstrated that dose reduction is safe for patients in deep molecular remission and may be considered prior to a TFR attempt.

Summary

Dose modifications are widely used to prevent and manage the toxicities of TKIs. With adequate monitoring, dose optimization is safe, reduces side effects, and improves quality-of-life for patients. Clinical trials of dose optimization are currently recruiting across all approved TKIs and will lead to further personalization of therapy for CP-CML patients in the future.