Is it possible to discontinue imatinib mesylate therapy in Chronic Myeloid Leukemia patients with undetectable BCR/ABL? A case report and a review of the literature

Psychological Factors Affecting the Willingness to Accept a Possible Tyrosine Kinase Inhibitor (TKI) Discontinuation in Chronic Myeloid Leukaemia (CML) Patients

PURPOSE

Patients with chronic myeloid leukemia (CML) who present a sustained deep molecular response (DMR) for a stable period of time might benefit from discontinuing tyrosine kinase inhibitors (TKIs). A significant number of patients seem able to reach this stage due to the availability of TKIs. However, many patients remain reluctant about TKI discontinuation and may refuse treatment interruption. The purpose of this study was to explore the clinical and psycho-cognitive factors that may influence the decision to discontinue TKI therapy, thereby gaining a better understanding of patients' viewpoints on TKI discontinuation.

PATIENTS AND METHODS

One hundred and nineteen patients diagnosed with CML aged between 34 and 69 were enrolled (67 males and 52 females). Different clinical information and psycho-cognitive aspects such as attitude toward risk behaviours, risk preferences, need for cognitive closure, and tendency to resist to changes were assessed through the administration of a battery of questionnaires.

RESULTS

A higher tendency toward risk behaviours and the tendency to focus on possible gain in the short term rather than on losses might represent important predictors for the willingness to accept TKI discontinuation. Possible relapses following interruption of the therapy are the most common reason for concern. Furthermore, lower levels of resistance to change and having previously experienced the desire to interrupt the therapy might lead patients to accept a higher probability of relapse risk when facing such a decision.

CONCLUSION

TKI discontinuation appears appealing and challenging at the same time for many CML patients, and different factors may influence this decision. Psychology plays a crucial role in assisting physician-patient communication and informed decision-making.

Present and future of molecular monitoring in chronic myeloid leukaemia

Currently, physicians treating chronic myeloid leukaemia (CML) patients can rely on a wide spectrum of therapeutic options: the best use of such options is essential to achieve excellent clinical outcomes and, possibly, treatment-free remission (TFR). To accomplish this, proper integration of expert clinical and laboratory monitoring of CML patients is fundamental. Molecular response (MR) monitoring of patients at defined time points has emerged as an important success factor for optimal disease management and BCR-ABL1 kinase domain mutation screening is useful to guide therapeutic reassessment in patients who do not achieve optimal responses to tyrosine kinase inhibitor therapy. Deeper MRs might be associated with improved long-term survival outcomes. More importantly, they are considered a gateway to TFR. In molecular biology, novel procedures and technologies are continually being developed. More sophisticated molecular tools and automated analytical solutions are emerging as CML treatment endpoints and expectations become more and more ambitious. Here we provide a critical overview of current and novel methodologies, present their strengths and pitfalls and discuss what their present and future role might be.

The choice dilemma in chronic hematological conditions: Why choosing is not only a medical issue? A psycho-cognitive perspective

Research in cognitive psychology focused on risk perception and decision making was shown to facilitate treatment choice and patient's satisfaction with decision in a number of medical conditions, increasing perceived alliance between patient and physician, and adherence to treatment. However, this aspect has been mostly neglected in the literature investigating choice of treatment for chronic hematological conditions. In this paper, a patient centered model and a shared decision making (SDM) approach to treatment switch in chronic hematological conditions, in particular chronic myeloid leukemia, atrial fibrillation, and β-thalassemia is proposed. These pathologies have a series of implications requiring important decisions about new available treatments. Although new generation treatments may provide a significant improvement in patient's health and health-related quality of life (HrQoL), a significant percentage of them is uncertain about or refuse treatment switch, even when strongly suggested by healthcare guidelines. Possible cognitive and emotional factors which may influence decision making in this field and may prevent appropriate risk-and-benefits evaluation of new treatment approaches are reviewed. Possible adaptive strategies to improve quality of care, patient participation, adherence to treatment and final satisfaction are proposed, and implications relatively to new treatment options available are discussed.

Rationale and protocol of CML study: cognitive and emotional impact of discontinuation of therapy in patients with chronic myeloid leukemia

INTRODUCTION

Discontinuation of therapy can be proposed to patients with chronic myelogenous leukemia (CML) who reach a sustained deep molecular response (DMR) for a minimum and stable period. Today, a considerable number of patients reach a sustained DMR, especially when they are treated with the latest drugs. Although new-generation treatments may provide significant improvement in terms of patient health and health-related quality of life, many patients are uncertain about discontinuation and may refuse a treatment switch.

METHODS

This study is an observational research project aimed at investigating, from a psychological point of view, possible cognitive and emotional components that can influence treatment discontinuation and treatment decisions in a cohort sample of 120 CML patients.

RESULTS

The expected results indicate that cognitive and emotional factors may influence decision-making in this setting and may prevent appropriate risk-and-benefit evaluation of new treatment approaches.

CONCLUSIONS

This is the first study that will analyze in depth all possible psychological variables that can interfere with the medical decision process of treatment discontinuation in CML, providing new insights for clinical practice.

Age and dPCR can predict relapse in CML patients who discontinued imatinib: the ISAV study

Imatinib is effective for the treatment of chronic myeloid leukemia (CML). However even undetectable BCR-ABL1 by Q-RT-PCR does not equate to eradication of the disease. Digital-PCR (dPCR), able to detect 1 BCR-ABL1 positive cell out of 10(7) , has been recently developed. The ISAV study is a multicentre trial aimed at validating dPCR to predict relapses after imatinib discontinuation in CML patients with undetectable Q-RT-PCR. CML patients under imatinib therapy since more than 2 years and with undetectable PCR for at least 18 months were eligible. Patients were monitored by standard Q-RT-PCR for 36 months. Patients losing molecular remission (two consecutive positive Q-RT-PCR with at least 1 BCR-ABL1/ABL1 value above 0.1%) resumed imatinib. The study enrolled 112 patients, with a median follow-up of 21.6 months. Fifty-two of the 108 evaluable patients (48.1%), relapsed; 73.1% relapsed in the first 9 months but 14 late relapses were observed between 10 and 22 months. Among the 56 not-relapsed patients, 40 (37.0% of total) regained Q-RT-PCR positivity but never lost MMR. dPCR results showed a significant negative predictive value ratio of 1.115 [95% CI: 1.013-1.227]. An inverse relationship between patients age and risk of relapse was evident: 95% of patients <45 years relapsed versus 42% in the class ≥45 to <65 years and 33% of patients ≥65 years [P(χ(2) ) < 0.0001]. Relapse rates ranged between 100% (<45 years, dPCR+) and 36% (>45 years, dPCR-). Imatinib can be safely discontinued in the setting of continued PCR negativity; age and dPCR results can predict relapse.

Molecular monitoring

More and more potent therapeutic approaches demand more and more sophisticated response monitoring. Soon after the introduction of the first tyrosine-kinase inhibitor (TKI) for chronic myeloid leukemia (CML) treatment, real time quantitative polymerase chain reaction (RQ-PCR) became the gold standard to follow the kinetics of reduction of disease burden and allow prognostic stratification. Continuous therapeutic improvement has led to increasingly ambitious treatment endpoints (now culminating in the possibility of achieving treatment free remission), which, in turn, has led to more and more refined measurement and definition of molecular response (MR) levels. Here, we will review the evolution of molecular response definitions and terminology, how specific MR levels currently provide key checkpoints in the context of optimal patient management, how molecular monitoring can best be performed nowadays and what future trends for further technological improvement can be.

Patient preferences for stopping tyrosine kinase inhibitors in chronic myeloid leukemia

BACKGROUND

We used an interview-assisted survey of patients with chronic myeloid leukemia (cml) at a single tertiary care centre to explore patient reactions to and preferences for, and the risk-acceptability of, stopping tyrosine kinase inhibitor (tki) treatment.

METHODS

The study included patients with confirmed cml currently being treated with a tki. The survey was conducted by structured interview using a standard form. Patient preferences were explored in a case-based scenario using 0%-100% visual analog scales and 5-point Likert scales. Data were analyzed using proportions for dichotomous variables and medians and interquartile ranges for continuous variables.

RESULTS

Of 63 patients approached, 56 completed the survey. Participant responses suggest that the idea of stopping tki use is appealing to many patients if there is a chance of long-term stable disease and a high probability of response upon restarting a tki. Participants were more likely to stop their tki as the risk of relapse decreased. Participants reported loss of disease control and failure of disease to respond to treatment as important concerns if they chose to stop their tki.

CONCLUSIONS

Given the current 60% estimated rate of relapse after discontinuation of tki therapy, most patients with cml chose to continue with tki. However, at the lower relapse rates reported with second-generation tkis, participants were more undecided, demonstrating a basic understanding of risk. Contrary to our hypothesis, neither compliance nor occurrence of side effects significantly affected patient willingness to stop their tki.

Discontinuation of tyrosine kinase inhibitors in chronic myeloid leukemia: when is this a safe option to consider?

Mrs G is a 54-year-old woman with a diagnosis of chronic-phase chronic myeloid leukemia dating back 8 years. She had a low-risk Sokal score at diagnosis and was started on imatinib mesylate at 400 mg orally daily within one month of her diagnosis. Her 3-month evaluation revealed a molecular response measured by quantitative RT-PCR of 1.2% by the International Scale. Within 6 months of therapy, she achieved a complete cytogenetic response, and by 18 months, her BCR-ABL1 transcript levels were undetectable using a quantitative RT-PCR assay with a sensitivity of ≥ 4.5 logs. She has maintained this deep level of response for the past 6.5 years. Despite her excellent response to therapy, she continues to complain of fatigue, intermittent nausea, and weight gain. She is asking to discontinue imatinib mesylate and is not interested in second-line therapy. Is this a safe and reasonable option for this patient?

Is going for cure in chronic myeloid leukemia possible and justifiable?

After more than a decade of treatment of chronic myeloid leukemia (CML) patients with the BCR-ABL tyrosine kinase inhibitor imatinib, and despite the impressive clinical results of this targeted therapeutic, many questions remain unresolved. One major question is how to cure CML, and the next step for the future will be to address this key issue. CML is a good model of cancer. The fact that the majority of CML patients who respond very well but discontinue tyrosine kinase inhibitors later show evidence of molecular recurrence focuses attention on the need for further research on leukemic stem cells. The challenge now is to understand why, after stopping treatment, the leukemia recurs in some patients but not in others. If we win this battle, this progress will certainly benefit the treatment and management of other leukemias and solid tumors and will validate this new topic.

Chronic myeloid leukemia stem cells in the era of targeted therapies: resistance, persistence and long-term dormancy

Targeted therapies of chronic myeloid leukemia (CML) using tyrosine kinase inhibitors (TKI) have profoundly changed the natural history of the disease with a major impact on survival. Molecular monitoring with BCR-ABL quantification shows that a status of undetectable molecular residual disease (UMRD) is obtained in a significant minority of patients. However, it remains unclear whether these patients are definitively cured of their leukemia. Imatinib mesylate withdrawal trials have demonstrated the rapid appearance of the malignant clone in the majority of the patients whereas some patients remain in a state of UMRD. It has clearly been demonstrated that the most primitive stem cells are refractory to all TKIs used in clinical practice. In addition, long-term dormancy is one of the most fundamental characteristics of hematopoietic stem cells. In this context, we have recently undertaken a systematic analysis of the bone marrow stem cell compartment in several patients in durable UMRD. We have demonstrated the long-term persistence of a considerable amount of BCR-ABL-expressing stem cells, even in the absence of relapse. The phenomenon of long-term leukemic stem cell dormancy is of major importance in CML and one of the key questions in cancer biology in general. We discuss, here, the potential mechanisms, including intrinsic and microenvironmental factors, that control the response of leukemic stem cells (LSCs) to targeted therapies and potential novel strategies currently in progress with a curative intent. Moreover, we propose a molecular evaluation of the residual LSC compartment in selected patients in order to develop rational TKI-cessation strategies in CML.

Low BCR-ABL expression levels in hematopoietic precursor cells enable persistence of chronic myeloid leukemia under imatinib

BCR-ABL overexpression and stem cell quiescence supposedly contribute to the failure of imatinib mesylate (IM) to eradicate chronic myeloid leukemia (CML). However, BCR-ABL expression levels of persisting precursors and the impact of long-term IM therapy on the clearance of CML from primitive and mature bone marrow compartments are unclear. Here, we have shown that the number of BCR-ABL-positive precursors decreases significantly in all bone marrow compartments during major molecular remission (MMR). More importantly, we were able to demonstrate substantially lower BCR-ABL expression levels in persisting MMR colony-forming units (CFUs) compared with CML CFUs from diagnosis. Critically, lower BCR-ABL levels may indeed cause IM insensitivity, because primary murine bone marrow cells engineered to express low amounts of BCR-ABL were substantially less sensitive to IM than BCR-ABL-overexpressing cells. BCR-ABL overexpression in turn catalyzed the de novo development of point mutations to a greater extent than chemical mutagenesis. Thus, MMR is characterized by the persistence of CML clones with low BCR-ABL expression that may explain their insensitivity to IM and their low propensity to develop IM resistance through kinase point mutations. These findings may have implications for future treatment strategies of residual disease in CML.

BCR-ABL transcript dynamics support the hypothesis that leukemic stem cells are reduced during imatinib treatment

PURPOSE

Imatinib induces a durable response in most patients with Philadelphia chromosome-positive chronic myeloid leukemia, but it is currently unclear whether imatinib reduces the leukemic stem cell (LSC) burden, which may be an important step toward enabling safe discontinuation of therapy. In this article, we use mathematical models of BCR-ABL levels to make inferences on the dynamics of LSCs.

EXPERIMENTAL DESIGN

Patients with at least 1 BCR-ABL transcript measurement on imatinib were included (N = 477). Maximum likelihood methods were used to test 3 potential hypotheses of the dynamics of BCR-ABL transcripts on imatinib therapy: (i) monoexponential, in which there is little, if any, decline in BCR-ABL transcripts; (ii) biexponential, in which patients have a rapid initial decrease in BCR-ABL transcripts followed by a more gradual response; and (iii) triexponential, in which patients first exhibit a biphasic decline but then have a third phase when BCR-ABL transcripts increase rapidly.

RESULTS

We found that most patients treated with imatinib exhibit a biphasic decrease in BCR-ABL transcript levels, with a rapid decrease during the first few months of treatment, followed by a more gradual decrease that often continues over many years.

CONCLUSIONS

We show that the only hypothesis consistent with current data on progenitor cell turnover and with the long-term, gradual decrease in the BCR-ABL levels seen in most patients is that these patients exhibit a continual, gradual reduction of the LSCs. This observation may explain the ability to discontinue imatinib therapy without relapse in some cases.

Malignancies occurring during therapy with tyrosine kinase inhibitors (TKIs) for chronic myeloid leukemia (CML) and other hematologic malignancies

Success of tyrosine kinase inhibitors (TKIs) in chronic myeloid leukemia (CML) has given patients hope for a long disease-free-survival. A longer survival raises the question of late effects, including development of another malignancy. Records of 1445 patients with CML/myeloproliferative neoplasm or other hematologic malignancies treated with TKIs were reviewed to investigate frequency and characteristics of second malignancies (other than acute myeloid leukemia, acute lymphocytic leukemia, or myelodysplastic syndrome). The number of second cancers was compared with the number expected from the Surveillance, Epidemiology, and End Results database. After a median follow-up of 107 months (range, 13-362 months) after CML/myeloproliferative neoplasm diagnosis, 66 patients (4.6%) developed 80 second cancers, including skin (31%), prostate (15%), melanoma (13%), digestive system (10%), kidney (4%), thyroid (4%), breast (3%), chronic lymphocytic leukemia (3%), hepatobiliary (3%), and other cancers (14%). Excluding nonmelanoma skin cancers, 55 second cancers were seen in 51 (3.5%) of all patients treated. The risk of second cancer was lower than expected (observed-to-expected ratio, 0.6; 95% confidence interval, 0.44-0.81). Second cancers occur in a small percentage of patients receiving therapy with TKIs for hematologic malignancies, mostly CML. No evidence at the moment suggests that exposure to TKIs increases the risk of developing second cancers.

Uncommon or delayed adverse events associated with imatinib treatment for chronic myeloid leukemia

Imatinib, a tyrosine kinase inhibitor, is the first-line therapy for chronic myeloid leukemia (CML). The majority of patients continue treatment for their lifespan because discontinuation generally results in relapse. Many patients treated with imatinib experience adverse events (AEs) at some time during their treatment. Commonly encountered AEs and their management are well known. However, in addition to the common AEs with imatinib, there is a significant number of patients who display either uncommon or delayed AEs. These events can involve cardiac, renal, or dermatologic problems, and fluid retention. Herein, we review these less-than-common side effects and the hazard of administering imatinib during pregnancy. While chronic treatment with imatinib has revolutionized CML prognosis, physicians should be aware of both the common and uncommon adverse reactions.

NCCN Task Force report: tyrosine kinase inhibitor therapy selection in the management of patients with chronic myelogenous leukemia

The advent of imatinib has dramatically improved outcomes in patients with chronic myelogenous leukemia (CML). It has become the standard of care for all patients with newly diagnosed chronic-phase CML based on its successful induction of durable responses in most patients. However, its use is complicated by the development of resistance in some patients. Dose escalation might overcome this resistance if detected early. The second-generation tyrosine kinase inhibitors (TKIs) dasatinib and nilotinib provide effective therapeutic options for managing patients resistant or intolerant to imatinib. Recent studies have shown that dasatinib and nilotinib provide quicker and potentially better responses than standard-dose imatinib when used as a first-line treatment. The goal of therapy for patients with CML is the achievement of a complete cytogenetic response, and eventually a major molecular response, to prevent disease progression to accelerated or blast phase. Selecting the appropriate TKI depends on many factors, including disease phase, primary or secondary resistance to TKI, the agent's side effect profile and its relative effectiveness against BCR-ABL mutations, and the patient's tolerance to therapy. In October 2010, NCCN organized a task force consisting of a panel of experts from NCCN Member Institutions with expertise in the management of patients with CML to discuss these issues. This report provides recommendations regarding the selection of TKI therapy for the management of patients with CML based on the evaluation of available published clinical data and expert opinion among the task force members.

Excellent outcomes of children with CML treated with imatinib mesylate compared to that in pre-imatinib era

Allogeneic hematopoietic stem cell transplantation (HSCT) and tyrosine kinase inhibitor have revolutionized the treatment of patients with chronic myeloid leukemia (CML). In this study, the clinical impact of HSCT and imatinib mesylate (IM) was retrospectively analyzed in 28 children with CML treated in our institutes from 1984 to 2008. Twelve patients were given oral IM. At 36 months after initiation of IM therapy, the complete cytogenetic response rate was 90.9%, and the major molecular response rate was 36.4%. Sixteen children received allogeneic HSCT without administration of IM. The stage of disease at transplantation was: first chronic phase (n = 10), second chronic phase (n = 2), accelerated phase (n = 2), and blastic crisis (n = 2). The progression rate was significantly lower in patients treated with IM than in those treated without IM (0 vs. 28.6%, p = 0.006). In summary, the survival outcomes of pediatric patients with CML were dramatically improved by treatment with IM compared to HSCT.

Discontinuation of imatinib in patients with chronic myeloid leukaemia who have maintained complete molecular remission for at least 2 years: the prospective, multicentre Stop Imatinib (STIM) trial

BACKGROUND

Imatinib treatment significantly improves survival in patients with chronic myeloid leukaemia (CML), but little is known about whether treatment can safely be discontinued in the long term. We aimed to assess whether imatinib can be discontinued without occurrence of molecular relapse in patients in complete molecular remission (CMR) while on imatinib.

METHODS

In our prospective, multicentre, non-randomised Stop Imatinib (STIM) study, imatinib treatment (of >2 years duration) was discontinued in patients with CML who were aged 18 years and older and in CMR (>5-log reduction in BCR-ABL and ABL levels and undetectable transcripts on quantitative RT-PCR). Patients who had undergone immunomodulatory treatment (apart from interferon α), treatment for other malignancies, or allogeneic haemopoietic stem-cell transplantation were not included. Patients were enrolled at 19 participating institutions in France. In this interim analysis, rate of relapse was assessed by use of RT-PCR for patients with at least 12 months of follow-up. Imatinib was reintroduced in patients who had molecular relapse. This study is registered with ClinicalTrials.gov, number NCT00478985.

FINDINGS

100 patients were enrolled between July 9, 2007, and Dec 17, 2009. Median follow-up was 17 months (range 1-30), and 69 patients had at least 12 months follow-up (median 24 months, range 13-30). 42 (61%) of these 69 patients relapsed (40 before 6 months, one patient at month 7, and one at month 19). At 12 months, the probability of persistent CMR for these 69 patients was 41% (95% CI 29-52). All patients who relapsed responded to reintroduction of imatinib: 16 of the 42 patients who relapsed showed decreases in their BCR-ABL levels, and 26 achieved CMR that was sustained after imatinib rechallenge.

INTERPRETATION

Imatinib can be safely discontinued in patients with a CMR of at least 2 years duration. Imatinib discontinuation in this setting yields promising results for molecular relapse-free survival, raising the possibility that, at least in some patients, CML might be cured with tyrosine kinase inhibitors.

Outcome of 125 children with chronic myelogenous leukemia who received transplants from unrelated donors: the Japan Marrow Donor Program

Because of a small number of patients, only a few studies have addressed the outcome of bone marrow transplantation (BMT) in children with Philadelphia chromosome-positive (Ph+) chronic myelogenous leukemia (CML), who receive graft from a volunteer-unrelated donor (VUD), especially after practical application of imatinib mesylate. The outcomes of BMT from a VUD in 125 children with Ph+ CML were retrospectively reviewed. Patients were identified through the Japan Marrow Donor Program as having undergone BMT between 1993 and 2005 and were aged 1-19 years at the time of transplant (median age, 14 years). The probabilities of 5-year overall survival (OS) and leukemia-free survival (LFS) were 59.3% and 55.5%, respectively. Multivariate analysis identified the following unfavorable survival factors: infused total nucleated cell dose<314 x 10(6) /kg (relative risk [RR]=2.43; 95% confidence interval [CI]=1.33-4.44; P=.004), advanced phase (RR=2.43; 95% CI=1.37-4.31; P=.004), and no major cytogenetic response (MCyR) at the time of BMT (RR=6.55; 95% CI=1.98-21.6; P=.002). Of the 17 patients treated with imatinib, 15 (88%) achieved MCyR at the time of BMT, and this group had an excellent 5-year OS of 81.9%. Disease phase, infused total nucleated cell dose, and cytogenetic response were independent risk factors for survival of unrelated BMT. These findings provide important information for assessing the indications for and improving outcome in unrelated BMT for the treatment of pediatric CML.