Chronic Myelogenous Leukemia: Pregnancy in the Era of Stopping Tyrosine Kinase Inhibitor Therapy

Outcome after short exposure to tyrosine kinase inhibitors in pregnant female patients with chronic myeloid leukemia

Unintended pregnancy for female patients with chronic myeloid leukemia (CML) raises the discussion of treatment choices due to the teratogenicity of tyrosine kinase inhibitor (TKI). We report 51 accidental pregnant CML chronic phase (CP) patients with TKI withdrawal immediately after pregnancy from December 2010 to February 2024 to observe the effect of short exposure to TKI on the fetus and the infant outcomes. 59 pregnancies resulted in 100% normal childbirth without birth abnormalities. The median TKI exposure duration was 4 (4-20) weeks in 58 pregnancies, and one pregnancy avoided TKI exposure due to treatment discontinuation of the patient with treatment-free remission (TFR). All newborns had normal birth weight except one premature infant with low birth weight less than the 10th percentile. Up to now, all the children are in good health. 13 (25.5%) and 30 (58.8%) patients had achieved major molecular response (MMR) and deep molecular response (DMR) at pregnancy, respectively. After TKI discontinuation, loss of MMR and complete hematologic response occurred in 6 (46.2%) and 2 (25.0%) patients at delivery, respectively. 38 patients resumed TKI treatment after delivery, and 13 patients without DMR loss sustained TFR after delivery. The median time to regain MMR and DMR were 3 (2-6) months and 6 (1-28) months, respectively. These results demonstrate that TKI discontinuation during pregnancy is feasible for CML-CP patients, and short TKI exposure of pregnant patients has little influence on children's growth and development.

Evaluation of contraception methods in chronic myeloid leukemia patients: A Turkish multicenter study

BACKGROUND AND AIM

Chronic myeloid leukemia (CML) incidence has recently increased in younger individuals. With time, given the nature of the disease and available therapies, as well as the existing paucity and inconsistency of advice, worries about fertility have surfaced. With all these clear unknowns, we designed this study to raise awareness among both physicians and CML patients about whether male and female patients of childbearing age were using contraception at the time of diagnosis, and if so, which methods they were using. In this context, this study aimed to evaluate the contraception methods in patients with CML.

MATERIALS AND METHODS

Eighteen centres from Turkey participated in the study. Male and female patients of childbearing age diagnosed with chronic and accelerated phase CML between the years 2000 and 2024 were evaluated retrospectively.

RESULTS

Of the two hundred and thirty-two patients included, one hundred and twenty-five (53.9%) of these patients were female and 107 (46.1%) were male. At diagnosis, all female patients were in the childbearing age, and male patients were sexually active. The median age at diagnosis of the patients was 38 (range, 18-77) years. Eighty-six (68.8%) female patients were using any contraception method, while this was 53.2% (n = 57) among male patients.

CONCLUSION

In conclusion, since CML patients are diagnosed at an earlier age and the desire of these patients to have children, adequate information and evaluation should be provided regarding fertility and contraception issues, especially in female patients, from the moment of diagnosis.

Male Fertility and Fatherhood in Chronic Myeloid Leukemia: Current Understanding and Future Perspectives

Chronic myeloid leukemia (CML), while traditionally a disease of the elderly, has recently risen in incidence among younger patients. Hence, fertility concerns have emerged considering the disease process and treatments, especially with the current scarce and conflicting recommendations. This review explores the impact of CML treatments including the first-line tyrosine kinase inhibitors (TKIs) and other treatments on male fertility in chronic myeloid leukemia (CML) patients. The aim of this review was to compile the available evidence on male fertility to ultimately tailor treatment plans for male CML patients for whom fertility and future chances for conception pose a concern. The data available on the conventional and newer TKIs to address fertility concerns were reviewed, particularly the potential long- and short-term effects. Also, the possible side effects on subsequent generations were a crucial focus point of this review to reach a more comprehensive CML management approach. We found and compared the evidence on TKIs approved to treat CML. We also reported the effects of hydroxyurea, interferon, and transplantation, which are considered second-line treatments. Our findings suggest that these drugs might have an undiscovered effect on fertility. More research with larger sample sizes and longer follow-up periods is essential to solidify our understanding of these effects.

Importance of TKI treatment duration in treatment-free remission of chronic myeloid leukemia: results of the D-FREE study

Treatment-free remission (TFR) is a new goal for patients with chronic myeloid leukemia in chronic phase (CML-CP) with a sustained deep molecular response (DMR) to treatment with tyrosine kinase inhibitors (TKIs). However, optimal conditions for successful TFR in patients treated with second-generation (2G)-TKIs are not fully defined. In this D-FREE study, treatment discontinuation was attempted in newly diagnosed CML-CP patients treated with the 2G-TKI dasatinib who achieved BCR-ABL1 levels of ≤ 0.0032% (MR4.5) on the international scale (BCR-ABL1IS) and maintained these levels for exactly 1 year. Of the 173 patients who received dasatinib induction therapy for up to 2 years, 123 completed and 60 (48.8%) reached MR 4.5. Among the first 21 patients who maintained MR4.5 for 1 year and discontinued dasatinib, 17 experienced molecular relapse defined as loss of major molecular response (BCR-ABL1IS > 0.1%) confirmed once, or loss of MR4 (BCR-ABL1IS > 0.01%) confirmed on 2 consecutive assessments. The estimated molecular relapse-free survival rate was 16.7% at 12 months. This study was prematurely terminated according to the protocol's safety monitoring criteria. The conclusion was that sustained DMR for just 1 year is insufficient for TFR in CML-CP patients receiving dasatinib for less than a total of 3 years of treatment.

Acute leukemias in pregnant women: Results of a retrospective study at a local tertiary-care hospital in Japan

Leukemia may rarely develop in a woman during pregnancy, posing clinical challenges to the patient, fetus, family, and medical staff managing malignancy and pregnancy. We retrospectively analyzed cases of pregnancy-associated leukemia consecutively diagnosed and treated at a local tertiary-care hospital in Nagano, Japan, over the past 20 years. Five cases were identified among 377,000 pregnancies in the area (one in every 75,000 pregnancies), all involving acute leukemia (three acute myelogenous leukemia [AML] and two acute lymphoblastic leukemia [ALL]). The cases were diagnosed in the first trimester (n = 1), second trimester (n = 3), or third trimester (n = 1). There were no apparent pregnancy-associated delays in diagnosing and treating the cases. Three patients underwent induction chemotherapy during pregnancy, two of whom eventually delivered healthy babies. One of the five patients chose abortion before chemotherapy initiation. Two cases showing high-risk features at the diagnosis (AML with an FLT3-ITD mutation [n = 1] and relapsed ALL [n = 1]) eventually died despite consolidative allogeneic hematopoietic stem cell transplantation. Our results suggested that patients with pregnancy-associated acute leukemia can be treated similarly to nonpregnant patients, although pregnancy imposes particular clinical challenges that should be resolved with multidisciplinary care.

Family Planning and Pregnancy in Patients with Chronic Myeloid Leukemia

PURPOSE OF REVIEW

The goal of this review is to summarize what is known about pregnancy in women with chronic myeloid leukemia (CML): there are very few guidelines regarding how to treat women who are pregnant at the time of CML diagnosis, and similarly, few guidelines regarding family planning for women already on tyrosine kinase inhibitor therapy who might want to start family planning.

RECENT FINDINGS

Most patients with CML achieve excellent control with first line tyrosine kinase inhibitor therapy that includes either imatinib, dasatinib, nilotinib, or bosutinib. For men, tyrosine kinase inhibitor (TKI) therapy does not affect sperm number or function, and female partners of men on therapy who become pregnant do not have an increased risk of miscarriage or babies with fetal malformation. However, for women, all TKIs are teratogenic and should be avoided at least in the first trimester of pregnancy. However, a small study suggests that women who have achieved a stable deep response therapy can safely stop therapy prior to a planned pregnancy and may not need any intervention during the pregnancy. Another small study suggests that nilotinib and imatinib have the lowest rate of transfer across the placenta. Providing well-documented guidelines for women with CML is challenging as TKI therapy is teratogenic. However, valuable information can be gained from small series of patients as summarized here.

Tyrosine Kinase Inhibitor discontinuation in Chronic Myeloid Leukemia: eligibility criteria and predictors of success

TKI discontinuation proved to be safe and feasible in patients with CML with deep and durable molecular responses, introducing an additional treatment goal for these patients beyond overall survival. However, treatment interruption is a safe procedure only with appropriate patient selection and monitoring. Clinical and biological factors associated with better outcomes do not yet offer a precise stratification of patients according to their risk of relapse. This article aims at reviewing the leading studies present in the field in order to define eligibility criteria for discontinuation and predictors of success.

How I Treat Chronic Phase Chronic Myelogenous Leukemia

When imatinib, the first tyrosine kinase inhibitor (TKI) developed for use in chronic myelogenous leukemia (CML) was approved in 2001, the treatment of this disease was forever changed. Significant reductions in the molecular burden of disease were seen with the first generation TKI imatinib and with the addition of dasatinib (2006), nilotinib (2007), bosutinib (2012) and ponatinib (2013), deeper and more rapid reductions were noted. Physicians could begin to tailor TKI therapy to individual patients, and patients who did not respond to or could not tolerate first line therapy now had options. Importantly, the number of patients who developed accelerated or blast phase disease decreased dramatically. Research in CML continues to evolve and by presenting illustrative cases, this article will review some of the newer aspects of clinical care in this disease. Updated information regarding bosutinib and asciminib, the latter currently in clinical trials, will be presented; bosutinib is of particular interest as the drug's transit through the United States Food and Drug Administration (FDA) highlights the question of what is considered optimal response to TKI therapy. The challenge of understanding the cardiac safety data of ponatinib and the unique dosing schedule based on individual response will be discussed. Lastly, two cases will focus on features of TKI treatment that -remarkably- have become part of the treatment algorithm: family planning for women with CML and stopping therapy after meeting a specific treatment milestone.

Management of chronic myeloid leukemia during pregnancy among patients treated with a tyrosine kinase inhibitor: a single-Center experience

Tyrosine kinase inhibitors (TKIs) are teratogenic. Chronic myeloid leukemia (CML) is increasingly identified in younger patients who wish to conceive, the management of CML during pregnancy is challenging. We reviewed 51 pregnancies involving 37 patients (30 women, 10 with >1 pregnancy and 7 men) who were either diagnosed with CML during pregnancy or receiving TKI at the time of conception. Ten women were involved in >1 pregnancies. Fifteen women were diagnosed with CML during pregnancy: 10 were treated with hydroxyurea (n = 5), interferon-alfa (n = 3), leukapheresis (n = 1), or nilotinib (n = 1). There were 14 (82%) healthy babies born on term including 2 sets of twins, 2 spontaneous miscarriages (12%), and 1 elective abortion (6%). Within 1 month of delivery or abortion, all women started TKI and achieved MR4.5 (n = 6) and MMR (n = 8) within 3-48 months. One patient, treated with interferon during pregnancy, died of blast phase within 2 months. Four of the 14 remaining women later conceived 5 other pregnancies while on TKI (3 unplanned, 2 planned). Twenty-six patients (7 men; 19 women) conceived while on TKI, with a total of 36 pregnancies. Fifteen women had 20 unplanned pregnancies while receiving TKI and discontinued immediately upon recognition of pregnancy. The median time of TKI exposure was 3 weeks (range, 2-11). Five pregnancies ended in miscarriages and 3 in elective abortion. All 7 men fathered 7 full-term healthy babies. Of 20 babies born to men and women (including one set of twins), 1 had minor abnormality. Seven women lost their responses during pregnancy but at the end of pregnancy all but 2 resumed TKI and regained responses. Seven women involved in 9 planned pregnancies discontinued TKI prior to conception for a median of 4 months (range, 1-20); 3 lost responses during pregnancy. Only 5 patients resumed therapy after delivery. Outcomes were 6 full-term healthy babies, one premature, and two miscarriages. Conception among CML patients while on TKI could be uncomplicated. While patients may lose response following treatment interruption, nearly all regain response upon resuming therapy. Therapy during pregnancy is rarely needed.

Managing chronic myeloid leukemia for treatment-free remission: a proposal from the GIMEMA CML WP

Several papers authored by international experts have proposed recommendations on the management of BCR-ABL1+ chronic myeloid leukemia (CML). Following these recommendations, survival of CML patients has become very close to normal. The next, ambitious, step is to bring as many patients as possible into a condition of treatment-free remission (TFR). The Gruppo Italiano Malattie EMatologiche dell'Adulto (GIMEMA; Italian Group for Hematologic Diseases of the Adult) CML Working Party (WP) has developed a project aimed at selecting the treatment policies that may increase the probability of TFR, taking into account 4 variables: the need for TFR, the tyrosine kinase inhibitors (TKIs), the characteristics of leukemia, and the patient. A Delphi-like method was used to reach a consensus among the representatives of 50 centers of the CML WP. A consensus was reached on the assessment of disease risk (EUTOS Long Term Survival [ELTS] score), on the definition of the most appropriate age boundaries for the choice of first-line treatment, on the choice of the TKI for first-line treatment, and on the definition of the responses that do not require a change of the TKI (BCR-ABL1 ≤10% at 3 months, ≤1% at 6 months, ≤0.1% at 12 months, ≤0.01% at 24 months), and of the responses that require a change of the TKI, when the goal is TFR (BCR-ABL1 >10% at 3 and 6 months, >1% at 12 months, and >0.1% at 24 months). These suggestions may help optimize the treatment strategy for TFR.

Preservation of fertility in patients with hematological malignancies

Oncofertility is the medical field that bridges oncology and reproduction that seeks to give healthcare providers and patients the opportunity to optimize residual fertility. The treatment for hematological malignancies carries gonadal toxicity, so that the preservation of fertility should be considered in all patients in childhood, adolescence and young adulthood. Most patients who receive only chemotherapy remain fertile, whereas those who receive regimens consisting of high-dose alkylating agents or total body irradiation can develop permanent infertility. In postpubertal patients, there are established methods for preserving fertility, such as the cryopreservation of sperm, oocytes and embryos. Although ideally performed before the initiation of gonadotoxic treatment, these procedures for fertility preservation can be performed any time prior to the loss of gonadal function. In contrast, a standard option is not available in prepubertal patients, and the preservation of fertility must be sought through experimental methods. Future advances in reproductive medicine may overcome this limitation. Gonadal tissue cryopreservation might be performed in the hope that sperm or mature oocytes could later be extracted from cryopreserved tissue. Healthcare providers, including hematologists, reproductive endocrinologists, nurses, clinical psychotherapists and embryologists, need to optimize the patient's fertility through shared decision-making while always remaining aware of the rapidly progressing developments in reproductive medicine.

Chronic Myeloid Leukemia in Children: Challenges and Opportunities : Based on 7th Dr. I. C. Verma Excellence Award for Young Pediatricians Delivered as Oration on 29th Sept. 2019

Treatment with tyrosine kinase inhibitors (TKI) is an effective therapy for children and adolescents with chronic phase of chronic myeloid leukemia (CML). For the majority of patients with CML in low- and middle-income countries (LMIC), imatinib is the TKI of choice for reasons of cost, availability, and experience. Children are exposed to therapy for a greater proportion of their lifetime as compared to adults. The adverse effects of prolonged administration of TKI is a subject of ongoing research, as more experience is collected. Therapy with TKI is currently considered to be life-long. Trials on stopping treatment are ongoing to explore if it may be feasible in selected patients, as reported in adults. Growth-failure is a concerning adverse effect. Currently, it seems unclear if the final height attained is within the expected range of the mid-parenteral height and growth standards. Whether the children will achieve a normal height at the end of their growth potential or remain below the predicted range is critical to decide if therapeutic interventions (E.g., growth hormone therapy, or interruption in TKI) should be considered during the period of growth potential. Research on CML in children is at a relatively slow pace, largely due to the rarity of the disease. This provides a unique opportunity for research in population-dense LMICs, as several tertiary centers tend to have a sizable cohort of children and adolescents with CML on follow-up. This narrative summarises the challenges and opportunities in dealing with CML in children, particularly in reference to a center in LMIC.

Treatment-free remission in patients with chronic myeloid leukaemia

In the past few years, international treatment guidelines for chronic myeloid leukaemia have incorporated recommendations for attempting discontinuation of treatment with tyrosine-kinase inhibitors (TKIs) outside of the setting of a clinical trial with the aim of a treatment-free remission (TFR). Physicians involved in the treatment of chronic myeloid leukaemia need to be sufficiently well informed to guide patients through decision-making about the discontinuation of treatment with TKIs targeting BCR-ABL1 by providing a balanced assessment of the potential risks and benefits of stopping or continuing therapy. These guidelines also seek to ensure that the risks associated with being off treatment are kept to a minimum. In this Review, we summarize the clinical studies of TFR and how their results can guide routine clinical practice with a focus on specific aspects such as molecular monitoring and the pregnancy-specific risks associated with a TFR attempt in female patients. We also address the development of predictors of outcome after TKI discontinuation and present strategies that warrant further consideration to enable more patients to enter TFR.

Successful Planned Pregnancy through Vitrified-Warmed Embryo Transfer in a Woman with Chronic Myeloid Leukemia: Case Report and Literature Review

A 35-year-old female patient with chronic myeloid leukemia (CML) wanted to have a child. She had been treated with imatinib and had achieved major molecular remission, after which imatinib was intentionally discontinued, and interferon-α treatment was initiated. After three failed cycles of artificial insemination with her husband’s semen, the patient underwent treatment with assisted reproductive technology. After two cycles of in vitro fertilization, two embryos (8-cell stage and blastocyst) were cryopreserved. The patient again had elevated major BCR-ABL mRNA levels; thus, infertility treatment was discontinued. After 18 months of dasatinib treatment, major molecular remission was again observed, and the patient underwent vitrified–warmed embryo transfer with a single blastocyst. After that, she became pregnant. Discontinuation of tyrosine kinase inhibitors combined with the timely initiation of infertility treatments, including assisted reproductive technology, might thus be useful for treating women with CML who wish to become pregnant.

[Fertility and disease outcomes in patients with chronic myeloid leukemia]

Objective: To explore Fertility and disease outcomes in patients with chronic myeloid leukemia (CML) . Methods: Clinical and fertility outcomes of male (from Jul. 1998 to Feb. 2018) and female CML (from Sep. 2009 to Feb. 2018) patients were retrospectively analyzed at Peking University People's Hospital. Results: A total of 49 male CML patients and their spouses were enrolled. Before their spouses conceived, 34 patients were receiving tyrosine kinase inhibitor (TKI) imatinib, 9 with nilotinib, and 6 with dasatinib. At the time of conception, the median age of these male patients was 32 years (range, 25-48 years) , and the median TKI treatment duration was 36 months (range, 0.2-198 months) . One male patient having achieved complete hematologic response yet discontinuing TKI for a year developed a disease progression to blast crisis. The other 48 patients sustained stable disease. The total conception times were 61 and finally 55 infants were born including one with premature birth, two with low birth weight, and one with hypospadias receiving surgery. The other 18 female patients after pregnancy were enrolled. Two patients developed spontaneous abortions. Two received induced abortions. Fourteen gave birth to healthy infants without congenital malformation. The interval from diagnosis of CML to initiation of TKI was 4 months (range, 0.3-16 months) . During a median follow-up of 45 months (range from 7-114 months) , the estimated complete cytogenetic response (CCyR) rate, major molecular response (MMR) rate and molecular response(4.5) (MR(4.5)) rate by 5 years were 88.9%, 85.3% and 35.1%, respectively. The estimated failure-free survival, progression-free survival and overall survival were 64.2%, 90.9% and 90.9%, respectively. All 14 babies developed as normal. Conclusions: It seems that TKIs do not affect pregnancy outcome in the spouses of male CML patients, suggesting that withdrawal of TKIs is not necessary. Female CML patients have good pregnancy and disease outcomes in the TKI era.

Early Management of CML

PURPOSE OF REVIEW

The marked improvement in clinical outcomes for patients with chronic myeloid leukaemia (CML) can be solely attributed to the introduction of targeted therapies against the fusion oncoprotein, BCR-ABL1. However, patient responses, although generally positive, remain heterogenous. Careful drug selection, ensuring the optimal TKI, is chosen for each patient and involves a complex decision process which incorporates consideration of numerous factors.

RECENT FINDINGS

For some patients, with disease characteristics that indicate adverse intrinsic disease biology, more potent BCR-ABL1 inhibition is often appropriate, whereas other patients with major co-morbidities will benefit from a less aggressive approach to avoid life-shortening toxicities. For the vast majority of patients, the long-term goal of therapy will be the achievement of a deep molecular response and subsequent treatment-free remission and this consideration will play a large part in the drug selection process. We explore early management of CML, from the first presentation through to frontline therapy selection.

Planned Pregnancy in Female Patients with Chronic Myeloid Leukemia Receiving Tyrosine Kinase Inhibitor Therapy

BACKGROUND

The aim of this study was to explore outcomes of planned pregnancy in female patients with chronic myeloid leukemia (CML) on tyrosine kinase inhibitors (TKIs).

MATERIALS AND METHODS

Data of female patients proceeding with a planned pregnancy were retrospectively reviewed.

RESULTS

A total of 17 patients with CML who achieved at least a major molecular response (MMR) during imatinib (n = 13) or nilotinib (n = 4) therapy prior to a planned pregnancy were enrolled. At the time of TKI interruption, six were in MMR, two in molecular response 4 (MR4), and nine in molecular response 4.5 (MR4.5). TKI therapy was discontinued 6 weeks (range, 2-15 weeks) before conception in 4 patients and at gestational age of 4 weeks (range, 2-5 weeks) after determination of pregnancy in 13 patients. Apart from 1 patient who suffered a spontaneous abortion, 16 patients delivered uneventfully. A total of 10 patients lost MMR after stopping TKIs; 8 lost molecular response 2, and 3 lost complete hematological response. Log-rank analyses showed achieving MR4 (p = .030) or MR4.5 (p = .031), complete cytogenetic response duration ≥3.5 years (p = .049), and MMR duration ≥3.5 years (p = .040) were significantly associated with longer MMR-failure-free survival during TKI interruption.

CONCLUSION

Planned pregnancy might be pragmatic in female patients with CML on TKIs. Achieving deep molecular response and, importantly, MMR duration ≥3.5 years were significantly associated with maintaining MMR during pregnancy.

IMPLICATIONS FOR PRACTICE

Female patients with chronic myeloid leukemia on tyrosine kinase inhibitors (TKIs) wishing to conceive are currently advised to discontinue TKIs before conception. However, the ideal degree and duration of response before stopping TKI, in addition to whether there will be any adverse effect caused by a short exposure of TKI, is unknown. Data of 17 female patients, who achieved at least a major molecular response (MMR) before TKI interruption, was revised, and it was found that achieving deep molecular response and MMR duration ≥3.5 years was significantly associated with maintaining MMR during pregnancy. This provides direct evidence for a planned pregnancy strategy, and stopping TKI immediately after determination of pregnancy in female patients might be pragmatic.

The effect of tyrosine kinase inhibitor interruption and interferon use on pregnancy outcomes and long-term disease control in chronic myeloid leukemia

The management of CML in pregnancy is challenging with the need to balance disease control against potential teratogenic effects of TKI therapy. In this multi-center case-cohort study of 16 women in chronic phase, CML ceased TKI treatment pre- or post-conception during their first pregnancy. Thirteen patients were on imatinib; 9 ceased their TKI prior to conception and 7 ceased at pregnancy confirmation. Twelve patients had achieved either MMR or better at time of TKI cessation. Eleven women lost MMR during pregnancy and two patients lost CHR. Fourteen women reestablished MMR on TKI recommenced. The depth molecular response prior to conception appeared to correlate well with restoration of disease control on TKI recommencement though duration of MMR did not appear to be as important. While interruption of TKI treatment for pregnancy usually leads to loss of molecular response, loss of hematological response is uncommon and disease control is reestablished with resumption of therapy in the majority of women.

Successful pregnancies in patients with BCR-ABL-positive leukemias treated with interferon-alpha therapy during the tyrosine kinase inhibitors era

BACKGROUND

Management of pregnant patients with BCR-ABL-positive leukemia is challenging. Managing a patient who has been diagnosed while pregnant requires a different approach as compared to a patient who plans to become pregnant while on the treatment with tyrosine kinase inhibitor (TKI). Interferon (IFN)-alpha is a useful option in both situations due to teratogenic potential of TKIs.

METHODS

We presented a series of 12 successful pregnancies in 11 women with BCR-ABL-positive leukemia, whose leukemia was managed with IFN-alpha throughout their pregnancy.

RESULTS

All children have normal growth and development. All patients remained at least in hematological response and could start or resume TKI after delivery or breastfeeding.

CONCLUSION

Because of the increased risk of teratogenicity and spontaneous abortion in female patient with pregnancy, when receiving TKI, IFN-alpha can be considered a safe drug to be administered throughout pregnancy and could represent the drug of choice in this situation during the era of TKI therapy.