Safety and efficacy of nilotinib in adult patients with chronic myeloid leukemia: a post-marketing surveillance study in Korea

Background

Nilotinib is a tyrosine kinase inhibitor approved by the Ministry of Food and Drug Safety for frontline and 2nd line treatment of Philadelphia chromosome-positive chronic myeloid leukemia (Ph⁺ CML). This study aimed to confirm the safety and efficacy of nilotinib in routine clinical practice within South Korea.

Methods

An open-label, multicenter, single-arm, 12-week observational post-marketing surveillance (PMS) study was conducted on 669 Korean adult patients with Ph⁺ CML from December 24, 2010, to December 23, 2016. The patients received nilotinib treatment in routine clinical practice settings. Safety was evaluated by all types of adverse events (AEs) during the study period, and efficacy was evaluated by the complete hematological response (CHR) and cytogenetic response.

Results

During the study period, AEs occurred in 61.3% (410 patients, 973 events), adverse drug reactions (ADRs) in 40.5% (271/669 patients, 559 events), serious AEs in 4.5% (30 patients, 37 events), and serious ADRs in 0.7% (5 patients, 8 events). Furthermore, unexpected AEs occurred at a rate of 6.9% (46 patients, 55 events) and unexpected ADRs at 1.2% (8 patients, 8 events). As for the efficacy results, CHR was achieved in 89.5% (442/494 patients), and minor cytogenetic response or major cytogenetic response was achieved in 85.8% (139/162 patients).

Conclusion

This PMS study shows consistent results in terms of safety and efficacy compared with previous studies. Nilotinib was well tolerated and efficacious in adult Korean patients with Ph⁺ CML in routine clinical practice settings.

Intolerance to tyrosine kinase inhibitors in chronic myeloid leukemia: Definitions and clinical implications

Tyrosine kinase inhibitor (TKI) treatment targeting breakpoint cluster region-Abelson murine leukemia virus, the cause of chronic myeloid leukemia (CML), has revolutionized therapy for patients with this disease. The majority of patients with CML maintain favorable responses with long-term imatinib therapy; however, the availability of the second-generation TKIs nilotinib and dasatinib limits the need for patients intolerant to imatinib to continue with therapy. Unfortunately, there is currently no standard definition of intolerance to imatinib. Common Toxicity Criteria for grading adverse events, designed to identify acute toxicities, are often used to determine intolerance. However, because CML therapies are long-term, patient quality of life may provide a better measure of true intolerance. Several general methods of quantifying patient quality of life are in use for patients with CML, and a CML-specific variant of the M. D. Anderson Symptom Inventory is in development. An appropriate and consistent definition of intolerance will provide clinicians with an algorithm for managing their patients with severe or chronic adverse events during treatment with imatinib. As more long-term data become available for newer TKIs, the definition of intolerance in the context of CML treatment will continue to evolve to maximize the likelihood of durable responses and superior quality of life for patients.

Tyrosine kinase inhibitors: the first decade

The treatment of chronic myeloid leukemia (CML) drastically changed with the introduction of imatinib mesylate, a Bcr-Abl1 tyrosine kinase inhibitor (TKI), in 1998. By directly targeting this leukemogenic protein kinase, imatinib affords patients with CML sustained chromosomal remissions, which translate into prolonged survival. However, there has been concern over the emergence of resistance to imatinib, and some patients fail to respond or are intolerant of imatinib therapy because of untoward toxicity. This has spurred interest in developing novel TKIs to overcome the mechanisms of resistance that lead to treatment failure-most importantly, Bcr-Abl1 kinase domain mutations. Two of these second-generation TKIs, nilotinib and dasatinib, are approved worldwide for the treatment of CML after imatinib failure or intolerance. Although these agents are active, they fail in many patients because of the development of highly resistant mutations such as the T315I, against which several novel agents are currently being tested in clinical trials. This review provides an account of the progress made in the field of TKI therapy for CML over the past decade.

Practical considerations for the management of patients in the tyrosine kinase inhibitor era

Most tyrosine kinase inhibitor (TKI)-associated adverse events are easily managed by symptomatic relief, although dose reductions or interruptions may be necessary in some patients. Long-term follow-up of early clinical trials has shown that the majority of imatinib-associated adverse events generally occur early, and the incidence decreases over the course of therapy, making imatinib the treatment of choice for long-term administration. A lack of patient adherence to imatinib, due to the occurrence of adverse events or for other reasons, can decrease response rates, and may cause resistance or disease relapse. Patient adherence to TKI therapies is a critical consideration for successful, long-term management of patients with chronic myeloid leukemia (CML). In patients who remain intolerant to imatinib, the differing tolerability profiles of second-generation TKIs should be considered when determining a therapeutic course of action. Throughout the course of therapy for CML, early and successful management of adverse events will increase dose optimization and patient adherence, and thereby optimize responses.

Class effects of tyrosine kinase inhibitors in the treatment of chronic myeloid leukemia

Tyrosine kinase inhibitors have revolutionized the treatment of chronic myeloid leukemia (CML), offering patients several targeted therapeutic options that provide the possibility of sustained remissions and prolonged survival. With the availability of imatinib, nilotinib and dasatinib, physicians must weigh the efficacy and safety profile of each agent when choosing the best therapeutic option for individual patients. Each agent targets tyrosine kinases within the cell uniquely to cause the desired antiproliferative effect. In addition to inhibiting the BCR-ABL kinase, imatinib and nilotinib target the same array of other tyrosine kinases, including c-KIT and platelet-derived growth factor receptor (PDGFR), albeit with differing potencies. While targeting BCR-ABL with the highest potency among approved agents in CML, dasatinib also targets a broad array of off-target kinases, including SRC family members, PDGFR and EPHB4. The differences in kinase inhibition profiles among these agents in vitro probably account for the differing clinical safety profiles of these agents. This paper reviews the various kinases inhibited by imatinib, nilotinib and dasatinib, and describes the potential impact of kinase inhibition on the efficacy and safety of each agent.

Management of the advanced phases of chronic myelogenous leukemia in the era of tyrosine kinase inhibitors

Imatinib has revolutionised the management of chronic phase chronic myelogenous leukemia (CML). Unfortunately it has had less of an impact on the management of the advanced phases of CML. These historically difficult-to-treat phases of disease remain largely resistant to therapy. Even when responses are obtained with the tyrosine kinase inhibitors, they are brief, particularly in blast phase (BP) disease. Allogeneic stem cell transplantation is the only curative option for these patients and should be considered early as an integral part of the treatment plan. But transplant outcomes are dependent on cytogenetic and gross disease burden at the time of transplant. This review will compare and contrast the various tyrosine kinase- and non-tyrosine kinase inhibitor-based treatments for accelerated and BP CML before allogeneic transplantation.