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

SOHO State of the Art Updates and Next Questions: Chronic Myeloid Leukemia and Pregnancy: "Per Aspera Ad Astra"

Chronic myeloid leukemia (CML) has evolved from an invariably fatal disease to a chronic disorder that can be treated with targeted drugs and allows survival expectations approaching age-matched controls. Thus, pregnancy and conception in CML should not be precluded anymore; however, to ensure the well-being of both the mother and the developing fetus careful planning and management are required. Tyrosine Kinase Inhibitors (TKIs) are not genotoxic or carcinogenic but can pose a risk to the developing fetus, due to their teratogenic potential. The risk depends on the TKI and the stage of fetal development during exposure. Teratogenic risk is high in the first trimester of pregnancy when the baby's organs and structures are forming (5-12 weeks). If a female patient is on therapy it is advisable to stop therapy at the first positive pregnancy test (3-5 weeks) to maximize the length of treatment-free, and ideally to not treat until delivery. If needed, the medication plan during pregnancy may be adjusted. Interferons can be used at any time, imatinib and nilotinib have a reduced placental crossing and could be carefully used after 16 weeks, whereas dasatinib crosses the placenta and can induce problems throughout the whole gestation. Management of pregnancy in CML is complex. This manuscript is an update of the state of the art allowing healthcare providers to be informed of the different situations that can occur and their governance.

Chronic myeloid leukemia diagnosed in pregnancy: management and outcome of 87 patients reported to the European LeukemiaNet international registry

The management of chronic myeloid leukemia (CML) diagnosed during pregnancy is a rare and challenging situation. We report the treatment and outcome of 87 cases diagnosed in chronic phase from 2001-2022 derived from the largest international observational registry, supported by the European LeukemiaNet (ELN), of 400 pregnancies in 299 CML women. Normal childbirth occurred in 76% without an increased rate of birth abnormalities or life-threatening events, including in patients untreated or treated with interferon-α and/or imatinib in 2nd-3rd trimester. The low birth weight rate of 12% was comparable to that seen in the normal population. Elective and spontaneous abortions occurred in 21% and 3%, respectively. The complete hematologic response rate before labor was 95% with imatinib and 47% with interferon only. No disease progression during pregnancy was observed, 28% of the patients switched their therapy at varying times after delivery. Treatment options balance the efficacy and safety for mother and infant: interferon-α can commence in the 1st trimester and continued throughout in cases of good disease control and tolerability. Because of limited placental crossing, selected tyrosine kinase inhibitors (imatinib and nilotinib) seem to be safe and effective options in 2nd and 3rd trimester while hydroxycarbamide offers few benefits.

Managing women of child-bearing age with chronic myeloid leukaemia: safety and treatment considerations

INTRODUCTION

TKIs are paradigmatic in CML management and offer patients the prospect of a normal life expectancy. As a consequence, the focus of both the clinician and patient has shifted to considerations of quality of life, including the ability to parent children. Unfortunately, TKIs are teratogenic so that alternative treatment options may be required during pregnancy to adequately control disease and minimise risk.

AREAS COVERED

In this review, we summarise and provide an overview of the literature on the management of CML in women of child-bearing age. We discuss the various treatment options as well as their advantages, disadvantages and safety considerations. We discuss CML in the context of: 1) planned pregnancies with CML 2) unplanned pregnancies with CML 3) CML diagnosed during pregnancy.

EXPERT OPINION

Confidence in managing pregnancy and CML continues to grow. In the majority of cases, with careful planning and counselling, no treatment is required and disease control can be safely regained after pregnancy ends. In those who require treatment various options are available, and there is growing evidence to suggest that some TKIs may be safe in the later stages of pregnancy.

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.

Treatment of CML in pregnancy

Since the introduction of tyrosine kinase inhibitors (TKIs) at the beginning of the millennium, the outlook for patients with chronic myeloid leukemia (CML) has improved remarkably. As such, the question of life expectancy and survival has become less problematic while quality of life and family planning have become more so. While TKIs are the cornerstone of CML management, their teratogenicity renders them contraindicated during pregnancy. In recent years, patients who satisfy standardized criteria can stop TKI therapy altogether, and indeed, in eligible patients who wish to become pregnant, these objectives overlap. However, not all patients satisfy these criteria. Some pregnancies are unplanned, and a number of patients are pregnant when diagnosed with CML. In these patients the way forward is less clear, and there remains a paucity of good evidence available to guide treatment. In this article, we summarize the relevant literature and provide a framework for clinicians faced with the challenge of managing CML and pregnancy.

Leukemia Stem Cells as a Potential Target to Achieve Therapy-Free Remission in Chronic Myeloid Leukemia

Leukemia stem cells (LSCs, also known as leukemia-initiating cells) not only drive leukemia initiation and progression, but also contribute to drug resistance and/or disease relapse. Therefore, eradication of every last LSC is critical for a patient's long-term cure. Chronic myeloid leukemia (CML) is a myeloproliferative disorder that arises from multipotent hematopoietic stem and progenitor cells. Tyrosine kinase inhibitors (TKIs) have dramatically improved long-term outcomes and quality of life for patients with CML in the chronic phase. Point mutations of the kinase domain of BCR-ABL1 lead to TKI resistance through a reduction in drug binding, and as a result, several new generations of TKIs have been introduced to the clinic. Some patients develop TKI resistance without known mutations, however, and the presence of LSCs is believed to be at least partially associated with resistance development and CML relapse. We previously proposed targeting quiescent LSCs as a therapeutic approach to CML, and a number of potential strategies for targeting insensitive LSCs have been presented over the last decade. The identification of specific markers distinguishing CML-LSCs from healthy HSCs, and the potential contributions of the bone marrow microenvironment to CML pathogenesis, have also been explored. Nonetheless, 25% of CML patients are still expected to switch TKIs at least once, and various TKI discontinuation studies have shown a wide range in the incidence of molecular relapse (from 30% to 60%). In this review, we revisit the current knowledge regarding the role(s) of LSCs in CML leukemogenesis and response to pharmacological treatment and explore how durable treatment-free remission may be achieved and maintained after discontinuing TKI treatment.

Chemotherapy Can Interfere in Implantation in In-vitro Fertilization

Improvement in cancer treatments has allowed more women to plan a pregnancy once the disease is cured. The effects of chemotherapy on ovaries are well proven but those on the uterus, especially the endometrium and embryo implantation are still unknown. Usage of newer tyrosine kinase inhibitors such as nilotinib has revolutionized the management of leukemias. Although nilotinib has been reported to be safe in pregnancy, further studies are needed to evaluate its effect on the process of embryo implantation, especially in women undergoing in-vitro fertilization. We report a case where successful pregnancy outcome was achieved after stoppage of nilotinib before embryo transfer in a woman who had previous four failed attempts while on nilotinib and no other obvious cause of implantation failure. Despite optimal endometrial thickness and receptivity, the pale appearance of endometrium on hysteroscopy was attributed to be a possible effect of nilotinib and prompted us to withhold it.

Combination Therapies in Chronic Myeloid Leukemia for Potential Treatment-Free Remission: Focus on Leukemia Stem Cells and Immune Modulation

Although tyrosine Kinase Inhibitors (TKI) has revolutionized the treatment of chronic myeloid leukemia (CML), patients are not cured with the current therapy modalities. Also, the more recent goal of CML treatment is to induce successful treatment-free remission (TFR) among patients achieving durable deep molecular response (DMR). Together, it is necessary to develop novel, curative treatment strategies. With advancements in understanding the biology of CML, such as dormant Leukemic Stem Cells (LSCs) and impaired immune modulation, a number of agents are now under investigation. This review updates such agents that target LSCs, and together with TKIs, have the potential to eradicate CML. Moreover, we describe the developing immunotherapy for controlling CML.

Fertility considerations in targeted biologic therapy with tyrosine kinase inhibitors: a review

PURPOSE

To review the impact of tyrosine kinase inhibitors (TKIs) on fertility in men and women, embryo development, and early pregnancy, and discuss considerations for fertility preservation in patients taking TKIs.

METHODS

A comprehensive literature search using the PubMed database was performed through February 2021 to evaluate the current literature on imatinib, nilotinib, dasatinib, and bosutinib as it relates to fertility and reproduction. Published case series were analyzed for pregnancy outcomes.

RESULTS

TKIs adversely affect oocyte and sperm maturation, gonadal function, and overall fertility potential in a self-limited manner. There are insufficient studies regarding long-term consequences on fertility after discontinuation of TKIs. A total of 396 women and 236 men were on a first- or second-generation TKI at the time of conception. Of the women with detailed pregnancy and delivery outcomes (n = 361), 51% (186/361) resulted in a term birth of a normal infant, 4.3% (16/361) of pregnancies had a pregnancy complication, and 5% (20/361) of pregnancies resulted in the live birth of an infant with a congenital anomaly. About 22% of pregnant women (87/396) elected to undergo a termination of pregnancy, while 16% (63/396) of pregnancies ended in a spontaneous abortion. In contrast, of the 236 men, 87% conceived pregnancies which resulted in term deliveries of normal infants. Elective terminations, miscarriage rate, pregnancy complication rate, and incidence of a congenital malformation were all less than those seen in females (4%, 3%, 2%, and 2.5%, respectively).

CONCLUSION

Women should be advised to avoid conception while taking a TKI. Women on TKIs who are considering pregnancy should be encouraged to plan the pregnancy to minimize inadvertent first trimester exposure. In women who conceive while taking TKIs, the serious risk of relapse due to discontinuation of TKI should be balanced against the potential risks to the fetus. The risk of teratogenicity to a fathered pregnancy with TKI use is considerably lower. Fertility preservation for a woman taking a TKI can be considered to plan a pregnancy with a minimal TKI-free period. With careful monitoring, providers may consider a TKI washout period followed by controlled ovarian stimulation to cryopreserve oocytes or embryos, with a plan to resume TKIs until ready to conceive or to transfer an embryo to achieve pregnancy quickly. Fertility preservation is also indicated if a patient on TKI is requiring a gonadotoxic therapy or reproductive surgery impacting fertility.

Chronic Myeloid Leukemia: Modern therapies, current challenges and future directions

Chronic myeloid leukemia (CML) is a myeloproliferative neoplasm caused by a reciprocal translocation [t(9;22)(q34;q11.2)] that leads to the fusion of ABL1 gene sequences (9q34) downstream of BCR gene sequences (22q11) and is cytogenetically visible as Philadelphia chromosome (Ph). The resulting BCR/ABL1 chimeric protein is a constitutively active tyrosine kinase that activates multiple signaling pathways, which collectively lead to malignant transformation. During the early (chronic) phase of CML (CP-CML), the myeloid cell compartment is expanded, but differentiation is maintained. Without effective therapy, CP-CML invariably progresses to blast phase (BP-CML), an acute leukemia of myeloid or lymphoid phenotype. The development of BCR-AB1 tyrosine kinase inhibitors (TKIs) revolutionized the treatment of CML and ignited the start of a new era in oncology. With three generations of BCR/ABL1 TKIs approved today, the majority of CML patients enjoy long term remissions and near normal life expectancy. However, only a minority of patients maintain remission after TKI discontinuation, a status termed treatment free remission (TFR). Unfortunately, 5-10% of patients fail TKIs due to resistance and are at risk of progression to BP-CML, which is curable only with hematopoietic stem cell transplantation. Overcoming TKI resistance, improving the prognosis of BP-CML and improving the rates of TFR are areas of active research in CML.

Tyrosine kinase inhibitors and pregnancy in chronic myeloid leukemia: opinion, evidence, and recommendations

With survival expectation that of age-matched controls and given excellent response and worldwide access to tyrosine kinase inhibitors (TKI), family planning is increasingly important for a considerable fraction of patients with chronic myeloid leukemia (CML). The potential for therapy discontinuation ("treatment free remission") can afford the opportunity for a CML patient in deep response to plan and carry a pregnancy to full term without any therapeutic interventions. However, the reality of pregnancy desired or occurring when patients are not eligible for treatment-free remission raises the discussion of therapy choices during pregnancy. To date there are no official guidelines available to assist patients and clinicians with these decisions. This first position paper aims to analyze information published and presented surrounding this challenging area, with focus on different scenarios of disease burden and time from CML diagnosis, including CML discovered during pregnancy and pregnancy during CML treatment. An updated review, supported by data and presented together with authors' joint recommendations, is aimed to counsel the practical management of CML patients and pregnancy.

Chronic Myeloid Leukemia, Version 2.2021, NCCN Clinical Practice Guidelines in Oncology

Chronic myeloid leukemia (CML) is defined by the presence of Philadelphia chromosome (Ph) which results from a reciprocal translocation between chromosomes 9 and 22 [t(9;22] that gives rise to a BCR-ABL1 fusion gene. CML occurs in 3 different phases (chronic, accelerated, and blast phase) and is usually diagnosed in the chronic phase. Tyrosine kinase inhibitor therapy is a highly effective first-line treatment option for all patients with newly diagnosed chronic phase CML. This manuscript discusses the recommendations outlined in the NCCN Guidelines for the diagnosis and management of patients with chronic phase CML.

The effect of imatinib administered in the prenatal period on testis development in rats

BACKGROUND

The purpose of this study was to examine the effects of exposure to imatinib in the prenatal period on testis development in rats.

METHODS

Although all the study groups received intraperitoneal imatinib on prenatal days 1-8, no pregnancy occurred in the Imatinib-80 group. Immunohistochemical analysis, TUNEL, c-kit and PDGF staining revealed no difference between the groups in terms of positivity scoring.

RESULTS

A significant decrease was detected in total sperm counts in the Imatinib-20 group compared to the control group, but the sperm count was higher in the Imatinib-60 group than in the Imatinib-20 group. At biochemical measurements, the drug increased oxidative stress in the testis and serum in the Imatinib-20 group, but caused a decrease in tissue in the Imatinib-60 group. Thiol measurements revealed a decrease in the testis and serum in the Imatinib-60 group, while an increase in serum measurements was observed in the Imatinib-40 group. Analysis revealed no difference between the groups in terms of protamine and histone gene expression levels in testis tissue exposed to imatinib.

CONCLUSION

Our findings show that prenatal exposure to imatinib can lead to histopathological and biochemical changes in testis tissue, but that no adverse effect occurs in nuclear maturation of germ cells during spermiogenesis.

European LeukemiaNet 2020 recommendations for treating chronic myeloid leukemia

The therapeutic landscape of chronic myeloid leukemia (CML) has profoundly changed over the past 7 years. Most patients with chronic phase (CP) now have a normal life expectancy. Another goal is achieving a stable deep molecular response (DMR) and discontinuing medication for treatment-free remission (TFR). The European LeukemiaNet convened an expert panel to critically evaluate and update the evidence to achieve these goals since its previous recommendations. First-line treatment is a tyrosine kinase inhibitor (TKI; imatinib brand or generic, dasatinib, nilotinib, and bosutinib are available first-line). Generic imatinib is the cost-effective initial treatment in CP. Various contraindications and side-effects of all TKIs should be considered. Patient risk status at diagnosis should be assessed with the new EUTOS long-term survival (ELTS)-score. Monitoring of response should be done by quantitative polymerase chain reaction whenever possible. A change of treatment is recommended when intolerance cannot be ameliorated or when molecular milestones are not reached. Greater than 10% BCR-ABL1 at 3 months indicates treatment failure when confirmed. Allogeneic transplantation continues to be a therapeutic option particularly for advanced phase CML. TKI treatment should be withheld during pregnancy. Treatment discontinuation may be considered in patients with durable DMR with the goal of achieving TFR.

Fertility preservation in patients with hematologic malignancies and recipients of hematopoietic cell transplants

Patients with hematologic malignancies and those undergoing hematopoietic cell transplantation (HCT) face a complex set of challenges when considering options for fertility preservation (FP). There are no standard options for prepubertal children, and women with hematologic malignancies may not be eligible for standard FP options. Fortunately, initial therapies for most blood cancers are not highly gonadotoxic, affording an important opportunity for postremission counseling and referrals to fertility specialists. These patients face a high risk of relapse, and many will be referred for autologous or allogeneic HCT, which carries an extremely high risk of infertility. The expanding indications for HCT to include benign hematologic disorders as well as autoimmune diseases mandate that all hematologists are familiar with these risks. Oncofertility researchers are continually pushing the boundaries of what may be possible for our patients; in the meantime, communication and shared decision-making between hematologists and patients, as well as program-building, education, and outreach are essential to ensure that these patients, many of whom will be cured, maintain all of their options for a fulfilling life after intensive therapy.