Treatment-Free Remission: the New Goal in CML Therapy

Which Is the Best Tyrosine Kinase Inhibitor for Newly Diagnosed Chronic Myelogenous Leukemia?

The choice of frontline therapy for a patient with chronic phase chronic myeloid leukemia (CP-CML) can have a profound effect on the long-term clinical outcome. Currently, five tyrosine kinase inhibitors (TKIs-imatinib, dasatinib, nilotinib, bosutinib, and asciminib) are available for frontline therapy, but no single TKI is optimal for all patients. EUTOS long-term survival (ELTS) risk score, comorbidities, and treatment-free remission (TFR) priority are the key determinants of frontline TKI selection. Higher ELTS score, low age and comorbidity score, and a high priority for achievement of TFR would all favor the frontline use of a more potent TKI than imatinib. However, no TKI has improved survival compared with imatinib. In children with CP-CML, imatinib, dasatinib, and nilotinib have similar long-term efficacy, with ease of administration and impact of toxicities on quality of life being key considerations. Recent adult trials of reduced-dose dasatinib frontline showed that efficacy may be equivalent to standard-dose dasatinib with a better tolerability and safety profile, but experience is limited in patients with high-risk ELTS scores. The ASC4FIRST trial has confirmed that tolerability and molecular response with asciminib are superior to those with both imatinib and the second-generation (2G)-TKIs. While the overall treatment failure rate was lower with asciminib, the rate of BCR::ABL1 mutations that emerged with asciminib appeared to be higher. The risk of emergent mutations appears to be highly associated with the presence of ASXL1 mutations in the CML cells at diagnosis, but more work is needed to understand the implications of this finding.

Asciminib in patients with newly diagnosed chronic myeloid leukemia: results from the Japanese subgroup of ASC4FIRST

INTRODUCTION

The phase III ASC4FIRST study (NCT04971226) demonstrated superior efficacy and favorable safety and tolerability for asciminib against investigator-selected tyrosine kinase inhibitors (IS-TKI) in newly diagnosed chronic myeloid leukemia (CML). Results of a subgroup analysis in Japanese patients are presented here.

METHODS

Adult patients were randomized 1:1 to asciminib or IS-TKI following stratification by European Treatment and Outcome Study long-term survival risk score and prerandomization-selected TKI (imatinib and second-generation [2G] TKI strata). At week 48, major molecular response (MMR) rate in all patients and imatinib stratum (primary endpoints) were assessed along with MR4.0, MR4.5, and safety (cutoff: November 28, 2023).

RESULTS

In Japanese patients (asciminib, n = 21; IS-TKI, n = 17 [imatinib/2G TKI, n = 8/9]), the MMR rate was higher with asciminib (81.0%) than IS-TKI (47.1%), and versus imatinib (asciminib: 100%; imatinib: 25.0% [imatinib stratum]). More patients on asciminib than IS-TKI achieved MR4.0 (57.1% vs. 11.8%) and MR4.5 (28.6% vs. 5.9%). Fewer grade ≥ 3 adverse events (AEs; 42.9%, 50.0%, and 55.6%) and AEs leading to treatment discontinuation (0%, 37.5%, and 11.1%) occurred with asciminib than imatinib or 2G TKI.

CONCLUSION

Outcomes in Japanese patients were consistent with the ASC4FIRST overall population. Asciminib may be a therapy of choice for Japanese patients with CML.

Chemotherapeutic potential of radotinib against blood and solid tumors: A beacon of hope in drug repurposing

Tyrosine kinase inhibitors (TKIs) represent a pivotal class of targeted therapies in oncology, with multiple generations developed to address diverse molecular targets. Imatinib is the first TKI developed to target the BCR-ABL1 chimeric protein, which is the key driver oncogene implicated in Philadelphia chromosome-positive chronic myeloid leukemia (CML). Several second-generation tyrosine kinase inhibitors (2GTKIs), such as nilotinib, dasatinib, bosutinib, and radotinib (RTB), followed the groundbreaking introduction of imatinib. RTB occupies the unique position of being the least explored member of this class. While nilotinib, dasatinib, and bosutinib have garnered significant attention and extensive research focus, RTB remains relatively uncharted in comparison to its counterparts. Fundamental drug characteristics, such as the pharmacokinetic and pharmacodynamic properties of RTB, remain unavailable in existing sources. Compared to other 2GTKIs, RTB has been less utilized in combinatorial drug studies, and no investigations have been reported on its effects on solid tumors to date. However, the effects of RTB have been studied in acute myeloid leukemia (AML), multiple myeloma (MM), Parkinson's disease, and idiopathic pulmonary fibrosis (IPF). Although RTB has been investigated in some conditions, these studies are still in their preliminary stages and are comparatively lesser than studies on other 2GTKIs. This review is the first attempt that extensively presents a compilation of data on RTB and describes its therapeutic potential against blood and solid tumors. Further investigations on RTB could expand its chemotherapeutic usage in various solid tumors and enhance the possibility of drug repurposing in cancer therapy.

Hsa_circ_0006010 and hsa_circ_0002903 in peripheral blood serve as novel diagnostic, surveillance and prognostic biomarkers for disease progression in chronic myeloid leukemia

BACKGROUND

In the era of tyrosine kinase inhibitor (TKI) treatment, the progression of chronic myeloid leukemia (CML) remains a significant clinical challenge, and genetic biomarkers for the early identification of CML patients at risk for progression are limited. This study explored whether essential circular RNAs (circRNAs) can be used as biomarkers for diagnosing and monitoring CML disease progression and assessing CML prognosis.

METHODS

Peripheral blood (PB) samples were collected from 173 CML patients (138 patients with chronic phase CML [CML-CP] and 35 patients with accelerated phase/blast phase CML [CML-AP/BP]) and 63 healthy controls (HCs). High-throughput RNA sequencing (RNA-Seq) was used to screen dysregulated candidate circRNAs for a circRNA signature associated with CML disease progression. Quantitative real-time PCR (qRT-PCR) was used for preliminary verification and screening of candidate dysregulated genes, as well as subsequent exploration of clinical applications. Receiver operating characteristic (ROC) curve analysis, Spearman's rho correlation test, and the Kaplan-Meier method were used for statistical analysis.

RESULTS

The aberrant expression of hsa_circ_0006010 and hsa_circ_0002903 during CML progression could serve as valuable biomarkers for differentiating CML-AP/BP patients from CMP-CP patients or HCs. In addition, the expression levels of hsa_circ_0006010 and hsa_circ_0002903 were significantly associated with the clinical features of CML patients but were not directly related to the four scoring systems. Furthermore, survival analysis revealed that high hsa_circ_0006010 expression and low hsa_circ_0002903 expression indicated poor progression-free survival (PFS) in CML patients. Finally, PB hsa_circ_0006010 and hsa_circ_0002903 expression at diagnosis may also serve as disease progression surveillance markers for CML patients but were not correlated with PB BCR-ABL1/ABL1IS.

CONCLUSIONS

Our study demonstrated that PB levels of hsa_circ_0006010 and hsa_circ_0002903 may serve as novel diagnostic, surveillance, and prognostic biomarkers for CML disease progression and may contribute to assisting in the diagnosis of CML patients at risk for progression and accurate management of advanced CML patients.

Asciminib in Patients With CML-CP Previously Treated With ≥ 2 Tyrosine Kinase Inhibitors: 96-Week Results From the Japanese Subgroup Analysis of the ASCEMBL Study

Asciminib is a first-in-class BCR::ABL1 inhibitor that Specifically Targets the ABL1 Myristoyl Pocket (STAMP). It is approved worldwide and in Japan for chronic myeloid leukemia in chronic phase (CML-CP) with resistance or intolerance to previous tyrosine kinase inhibitor (TKI) therapy. In the Phase 3 ASCEMBL study, patients with CML-CP who received ≥ 2 prior ATP-competitive TKIs were randomized (2:1) to asciminib 40 mg twice-daily or bosutinib 500 mg once-daily. Here, we report the 96-week results of the subgroup analysis of Japanese patients (asciminib, n = 13; bosutinib, n = 3) in the ASCEMBL study. The MMR rate at Week 96 was 46.2% in asciminib-treated patients, increasing from Weeks 24 and 48. Patients who achieved MMR at Week 24 remained in MMR up to the Week 96 cutoff. While a high proportion of patients treated with asciminib remained on treatment at cutoff, none randomized to bosutinib were on treatment at Week 96. Despite the longer duration of exposure to asciminib, its safety and tolerability continued to be favorable with no new or worsening safety findings. Overall, the efficacy and safety outcomes in the Japanese subgroup were comparable with the ASCEMBL global study population, which supports the use of asciminib in Japanese patients with previously treated CML-CP.

Efficacy and safety of flumatinib in the treatment of newly diagnosed chronic myeloid leukemia in the chronic phase: A real-world single-center retrospective study, with a focus on premature drug discontinuation

PURPOSE

To assess the real-world efficacy and safety of flumatinib as first-line and post-line treatments for chronic myeloid leukemia in the chronic phase (CML-CP).

RESULTS

Among 141 patients receiving flumatinib as first-line and post-line treatment, the 12-month major molecular response (MMR) rates were 69.4% and 67.6%, respectively. The median time to response was 6 and 10.5 months, respectively. In post-line treatment, the early molecular response (EMR) of flumatinib as second-line is significantly superior to that of third-line treatment (3-month EMR rate: 79.2% vs. 39.3%, P<0.001; 3-month MMR rate: 45.8% vs. 21.4%, P=0.033). Contrastively, patients who switched to flumatinib due to intolerance had significantly higher MMR rates at 3, 6, and 12 months compared to patients who switched due to inadequate response (60.6% vs. 24.2%, P=0.003; 66.7% vs. 36.0%, P=0.027; 84.2% vs. 50.0%, P=0.038). Premature drug discontinuation was observed in 28.4% of the patients. Grades 3-4 hematologic adverse events (AEs) were identified as independent risk factors for premature drug discontinuation. Patients who discontinued treatment and those who previously received only imatinib therapy had a poorer molecular response and failure-free survival.

CONCLUSIONS

Flumatinib demonstrates favorable efficacy and safety. Treatment discontinuation can result in a poorer molecular response and long-term prognosis.

Managing and treating COVID-19 in patients with hematological malignancies: a narrative review and expert insights

Patients with hematologic malignancies (HMs) are at a significantly higher risk of contracting COVID-19 and experiencing severe outcomes compared to individuals without HMs. This heightened risk is influenced by various factors, including the underlying malignancy, immunosuppressive treatments, and patient-related factors. Notably, immunosuppressive regimens commonly used for HM treatment can lead to the depletion of B cells and T cells, which is associated with increased COVID-19-related complications and mortality in these patients. As the pandemic transitions into an endemic state, it remains crucial to acknowledge and address the ongoing risk for individuals with HMs. In this review, we aim to summarize the current evidence to enhance our understanding of the impact of HMs on COVID-19 risks and outcomes, identify particularly vulnerable individuals, and emphasize the need for specialized clinical attention and management. Furthermore, the impaired immune response to COVID-19 vaccination observed in these patients underscores the importance of implementing additional mitigation strategies. This may include targeted prophylaxis and treatment with antivirals and monoclonal antibodies as indicated. To provide practical guidance and considerations, we present two illustrative cases to highlight the real-life challenges faced by physicians caring for patients with HMs, emphasizing the need for individualized management based on disease severity, type, and the unique circumstances of each patient.

Exploration of treatment-free remission in CML, based on molecular monitoring

BACKGROUND

Typical chronic myelogenous leukemia (CML) is a myeloproliferative neoplasm caused by t(9; 22)(q34; q11) translocation. This chromosomal translocation forms the BCR::ABL1 fusion gene. The tyrosine kinase encoded by the BCR::ABL1 is considered to be the main pathogenic diver. BCR::ABL1 is not only a therapeutic target, but also a monitoring target. Monitoring of BCR::ABL1 reveals the progression of the disease and guides the next treatment. Now for CML, the target of treatment has been focused on treatment-free remission (TFR).

METHODS

We conducted a literature review of current developments of treatment-free remission and molecular monitoring methods.

RESULTS

More effective and sensitive CML monitoring methods such as digital droplet PCR (ddPCR) and next generation sequencing (NGS) have further studied the measurable residual disease (MRD) and clonal heterogeneity, which provides strong support for the exploration of TFR. We discussed some of the factors that may be related to TFR outcomes at the molecular level, along with some monitoring strategies.

CONCLUSION

Currently, predictive indicators for treatment-free remission outcomes and recurrence are lacking in clinical practice. In future, treatment-free remission research should focus on combining the clinical indicators with molecular monitoring and biological markers to personalize patient conditions and guide clinicians to develop individualized treatment plans, so that more patients with CML can achieve safer and stabler treatment-free remission.

Overcoming BCR::ABL1 dependent and independent survival mechanisms in chronic myeloid leukaemia using a multi-kinase targeting approach

BACKGROUND

Despite improved patient outcome using tyrosine kinase inhibitors (TKIs), chronic myeloid leukaemia (CML) patients require life-long treatment due to leukaemic stem cell (LSC) persistence. LSCs reside in the bone marrow (BM) niche, which they modify to their advantage. The BM provides oncogene-independent signals to aid LSC cell survival and quiescence. The bone-morphogenetic pathway (BMP) is one pathway identified to be highly deregulated in CML, with high levels of BMP ligands detected in the BM, accompanied by CML stem and progenitor cells overexpressing BMP type 1 receptors- activin-like kinases (ALKs), especially in TKI resistant patients. Saracatinib (SC), a SRC/ABL1 dual inhibitor, inhibits the growth of CML cells resistant to the TKI imatinib (IM). Recent studies indicate that SC is also a potent ALK inhibitor and BMP antagonist. Here we investigate the efficacy of SC in overcoming CML BCR::ABL1 dependent and independent signals mediated by the BM niche both in 2D and 3D culture.

METHODS

CML cells (K562 cell line and CML CD34+ primary cells) were treated with single or combination treatments of: IM, SC and the BMP receptors inhibitor dorsomorphin (DOR), with or without BMP4 stimulation in 2D (suspension) and 3D co-culture on HS5 stroma cell line and mesenchymal stem cells in AggreWell and microfluidic devices. Flow cytometry was performed to investigate apoptosis, cell cycle progression and proliferation, alongside colony assays following treatment. Proteins changes were validated by immunoblotting and transcriptional changes by Fluidigm multiplex qPCR.

RESULTS

By targeting the BMP pathway, using specific inhibitors against ALKs in combination with SRC and ABL TKIs, we show an increase in apoptosis, altered cell cycle regulation, fewer cell divisions, and reduced numbers of CD34+ cells. Impairment of long-term proliferation and differentiation potential after combinatorial treatment also occurred.

CONCLUSION

BMP signalling pathway is important for CML cell survival. Targeting SRC, ABL and ALK kinases is more effective than ABL inhibition alone, the combination efficacy importantly being demonstrated in both 2D and 3D cell cultures highlighting the need for combinatorial therapies in contrast to standard of care single agents. Our study provides justification to target multiple kinases in CML to combat LSC persistence.

Real-world Management of CML: Outcomes and Treatment Patterns

PURPOSE OF REVIEW

Chronic myeloid leukemia (CML) is a disease that previously signified a poor prognosis, but treatment options and outcomes have improved over the last several decades. Despite this, challenges remain in optimal management in clinical practice, as the characteristics in trial populations differ from patients who are treated in a real-world setting. This review describes recent updates in real-world treatment patterns and outcomes in patients with CML.

RECENT FINDINGS

Several analyses describing real-world practice patterns show that tyrosine kinase inhibitors (TKIs) are the most commonly prescribed agents in multiple lines of therapy. First-generation (1G) and second-generation (2G) TKIs are the most commonly prescribed, even in the third line and beyond. Third-generation (3G) TKIs are typically utilized in patients with resistant disease who are younger with fewer comorbidities. Hematopoietic stem cell transplant (HSCT) is utilized significantly less, given other treatment options available. The goals of treatment with CML have shifted to quality of life, cost savings, and treatment-free response (TFR). Despite clear guidelines for attempting TFR, discontinuation practice patterns remain inconsistent. TKIs are the mainstay of CML treatment, including those in later lines of therapy. In real-world practice, several challenges still remain with regard to optimal management. Specifically, ideal sequencing of treatments, side effect profiles of tyrosine kinase inhibitors (TKIs), current role and timing of transplant, and adherence to recommendations for attempting to achieve a treatment-free response (TFR). A national registry could characterize these practice patterns in order to find ways to optimize care for CML patients.

Setting up a network of comprehensive care for patients with chronic myeloid leukemia: Lessons learned from Tanzania

Over the last 2 decades, the introduction of targeted therapies and the advances in the detection of BCR::ABL1 oncogene have dramatically improved comprehensive care for patients with Chronic myeloid leukemia (CML). The once deadly malignancy has now transformed into a chronic disease with an overall patient survival approaching that of the age-matched general population. While excellent prognoses have been reported among CML patients in high-income countries, it is unfortunately not the same for those living in low and middle-income (LMIC) countries such as Tanzania. This disparity is largely contributed by barriers associated with the provision of comprehensive care including early diagnosis, access to treatment, and regular monitoring of the disease. In this review, we will share our experiences and lessons learned in setting up a network of comprehensive care for patients with CML in Tanzania.

Asciminib in the Treatment of Philadelphia Chromosome-Positive Chronic Myeloid Leukemia: Focus on Patient Selection and Outcomes

Tyrosine kinase inhibitors (TKIs) have significantly changed the treatment of chronic myeloid leukemia (CML) and improved outcomes for patients with CML in chronic phase (CML-CP) and accelerated phase (AP). Now armed with numerous effective therapeutic options, clinicians must consider various patient- and disease-specific factors when selecting the most appropriate TKI across lines of therapy. While most patients with CML expected to have a near-normal life expectancy due to the success of TKIs, emphasis has expanded beyond response and survival to include factors like quality of life, tolerability, and long-term toxicity management. Importantly, a subset of patients can achieve sustained deep molecular response and can attain treatment-free remission. Despite these successes, unmet needs remain related to CML treatment, including the persistent challenge of treatment resistance and intolerance, broadening treatment options for patients with resistance mutations or serious comorbidities, and focus on specific populations such as children and young adults. In particular, the only previously available treatments for patients with CML-CP with the T315I mutation were ponatinib, olverembatinib (exclusively approved for use in China at the time of this writing), omacetaxine, and hematopoietic stem cell transplantation. Asciminib has entered the CML treatment landscape as a new option for adult patients with CML-CP who have received ≥2 prior TKIs or those with the T315I mutation. Asciminib's unique mechanism of action, Specifically Targeting the ABL Myristoyl Pocket, sets it apart from traditional adenosine triphosphate-competitive TKIs. While asciminib may overcome unmet needs for patients with CML-CP and continues to be studied in other novel settings, guidance on how to integrate asciminib in treatment algorithms is needed. This review focuses on clinical data and how asciminib can overcome current unmet needs, discusses how to individualize patient selection, and highlights future directions to investigate asciminib in earlier lines of therapy and in children and adolescents.

Myelofibrosis at diagnosis is associated with the failure of treatment-free remission in CML patients

The management of patients with chronic myeloid leukemia (CML) has been revolutionized by the introduction of tyrosine kinase inhibitors (TKIs), which induce deep molecular responses so that treatment can eventually be discontinued, leading to treatment-free remission (TFR) in a subset of patients. Unfortunately, leukemic stem cells (LSCs) often persist and a fraction of these can again expand in about half of patients that attempt TKI discontinuation. In this study, we show that presence of myelofibrosis (MF) at the time of diagnosis is a factor associating with TFR failure. Fibrotic transformation is governed by the action of several cytokines, and interestingly, some of them have also been described to support LSC persistence. At the cellular level, these could be produced by both malignant cells and by components of the bone marrow (BM) niche, including megakaryocytes (MKs) and mesenchymal stromal cells (MSCs). In our cohort of 57 patients, around 40% presented with MF at diagnosis and the number of blasts in the peripheral blood and BM was significantly elevated in patients with higher grade of MF. Employing a CML transgenic mouse model, we could observe higher levels of alpha-smooth muscle actin (α-SMA) in the BM when compared to control mice. Short-term treatment with the TKI nilotinib, efficiently reduced spleen weight and BCR::ABL1 mRNA levels, while α-SMA expression was only partially reduced. Interestingly, the number of MKs was increased in the spleen of CML mice and elevated in both BM and spleen upon nilotinib treatment. Analysis of human CML-vs healthy donor (HD)-derived MSCs showed an altered expression of gene signatures reflecting fibrosis as well as hematopoietic support, thus suggesting MSCs as a potential player in these two processes. Finally, in our cohort, 12 patients qualified for TKI discontinuation, and here we observed that all patients who failed TFR had BM fibrosis at diagnosis, whereas this was only the case in 25% of patients with achieved TFR, further supporting the link between fibrosis and LSC persistence.

Molecular BCR::ABL1 Quantification and ABL1 Mutation Detection as Essential Tools for the Clinical Management of Chronic Myeloid Leukemia Patients: Results from a Brazilian Single-Center Study

Chronic myeloid leukemia (CML) is a well-characterized oncological disease in which virtually all patients possess a translocation (9;22) that generates the tyrosine kinase BCR::ABL1 protein. This translocation represents one of the milestones in molecular oncology in terms of both diagnostic and prognostic evaluations. The molecular detection of the BCR::ABL1 transcription is a required factor for CML diagnosis, and its molecular quantification is essential for assessing treatment options and clinical approaches. In the CML molecular context, point mutations on the ABL1 gene are also a challenge for clinical guidelines because several mutations are responsible for tyrosine kinase inhibitor resistance, indicating that a change may be necessary in the treatment protocol. So far, the European LeukemiaNet and the National Comprehensive Cancer Network (NCCN) have presented international guidelines on CML molecular approaches, especially those related to BCR::ABL1 expression. In this study, we show almost three years' worth of data regarding the clinical treatment of CML patients at the Erasto Gaertner Hospital, Curitiba, Brazil. These data primarily comprise 155 patients and 532 clinical samples. BCR::ABL1 quantification by a duplex-one-step RT-qPCR and ABL1 mutations detection were conducted. Furthermore, digital PCR for both BCR::ABL1 expression and ABL1 mutations were conducted in a sub-cohort. This manuscript describes and discusses the clinical importance and relevance of molecular biology testing in Brazilian CML patients, demonstrating its cost-effectiveness.

Project Confirm: Accelerated Drug Approvals for Chronic Myeloid Leukemia

The FDA has an accelerated approval program for drugs that have been identified as promising treatments for serious conditions when the available data suggest that the benefits outweigh the foreseeable risks. All of the currently available treatment options for chronic myeloid leukemia (CML) initially went through the accelerated approval program. Here, a group of academic CML experts, patient panelists, and members from the FDA convened to discuss the utility of the accelerated approval program as it pertains to CML, and the utility of this program in future drug development in this disease. The results of that discussion are summarized here.

Prospective monitoring of chronic myeloid leukemia patients from the time of TKI discontinuation: the fate of peripheral blood CD26+ leukemia stem cells

Introduction: In chronic myeloid leukemia (CML), about half of the patients achieving a deep and stable molecular response with tyrosine kinase inhibitors (TKIs) may discontinue TKI treatment without disease recurrence. As such, treatment-free remission (TFR) has become an ambitious goal of treatment. Given the evidence that deepness and duration of molecular response are necessary but not sufficient requisites for a successful TFR, additional biological criteria are needed to identify CML patients suitable for efficacious discontinuation. Leukemia stem cells (LSCs) are supposed to be the reservoir of the disease. Previously, we demonstrated that residual circulating CD34+/CD38-/CD26+ LSCs were still detectable in a consistent number of CML patients during TFR. Methods: CML LSCs could be easily identified by flow-cytometry as they express the CD34+/CD38-/CD26+ phenotype. In this study, we explored the role of these cells and their correlation with molecular response in a cohort of 109 consecutive chronic phase CML patients prospectively monitored from the time of TKI discontinuation. Results: After a median observation time of 33 months from TKI discontinuation, 38/109 (35%) patients failed TFR after a median time of 4 months, while 71/109 (65%) patients are still in TFR. At TKI discontinuation, peripheral blood CD26+LSCs were undetectable in 48/109 (44%) patients and detectable in 61/109 (56%). No statistically significant correlation between detectable/undetectable CD26+LSCs and the rate of TFR loss was found (p = 0.616). The incidence of TFR loss based on the type of TKI treatment was statistically significant for imatinib treatment compared to that of nilotinib (p = 0.039). Exploring the behavior of CD26+LSCs during TFR, we observed fluctuating values that were very variable between patients, and they were not predictive of TFR loss. Discussion: Up to date, our results confirm that CD26+LSCs are detectable at the time of TKI discontinuation and during TFR. Moreover, at least for the observation median time of the study, the persistence of "fluctuating" values of residual CD26+LSCs does not hamper the possibility to maintain a stable TFR. On the contrary, even patients discontinuing TKI with undetectable CD26+LSCs could undergo TFR loss. Our results suggest that factors other than residual LSCs "burden" playing an active role in controlling disease recurrence. Additional studies evaluating CD26+LSCs' ability to modulate the immune system and their interaction in CML patients with very long stable TFR are ongoing.

Dose optimization strategy of the tyrosine kinase inhibitors imatinib, dasatinib, and nilotinib for chronic myeloid leukemia: From clinical trials to real-life settings

With the advent of tyrosine kinase inhibitors (TKIs), the treatment prospects of chronic myeloid leukemia (CML) have changed markedly. This innovation can lengthen the long-term survival of patients suffering from CML. However, long-term exposure to TKIs is accompanied by various adverse events (AEs). The latter affect the quality of life and compliance of patients with CML, and may lead to serious disease progression (and even death). Recently, increasing numbers of patients with CML have begun to pursue a dose optimization strategy. Dose optimization may be considered at all stages of the entire treatment, which includes dose reduction and discontinuation of TKIs therapy. In general, reduction of the TKI dose is considered to be an important measure to reduce AEs and improve quality of life on the premise of maintaining molecular responses. Furthermore, discontinuation of TKIs therapy has been demonstrated to be feasible and safe for about half of patients with a stable optimal response and a longer duration of TKI treatment. This review focuses mainly on the latest research of dose optimization of imatinib, dasatinib, and nilotinib in CML clinical trials and real-life settings. We consider dose reduction in newly diagnosed patients, or in optimal response, or for improving AEs, either as a prelude to treatment-free remission (TFR) or as maintenance therapy in those patients unable to discontinue TKIs therapy. In addition, we also focus on discontinuation of TKIs therapy and second attempts to achieve TFR.

SOHO State of the Art Updates and Next Questions | Update on Treatment-Free Remission in Chronic Myeloid Leukemia (CML)

Tyrosine kinase inhibitor (TKI) discontinuation, also known as treatment-free remission (TFR) is currently one of the main goals of chronic myeloid leukemia (CML) therapy. TKI discontinuation should be considered in eligible patients for several reasons. Specifically, TKI therapy is associated with reduced quality of life, long-term side effects, and a heavy financial burden on both the patients and society. TKI discontinuation is a particularly important goal for younger patients diagnosed with CML because of the treatment's effects on their growth and development in addition to potential long-term side-effects. Numerous studies with thousands of patients have demonstrated the safety and feasibility of attempting TKI discontinuation in a select group of patients who have achieved a sustained deep molecular remission. With current TKIs, approximately 50% of patients will be eligible for attempting TFR of which only 50% will achieve a successful TFR. Therefore, in reality, only 20% of patients with newly diagnosed CML will achieve a successful TFR, and the majority of patients will need to continue TKI therapy indefinitely. However, several ongoing clinical trials are investigating treatment options for patients to achieve deeper remission with the ultimate goal of a cure, which is defined as being off drug with no evidence of disease.

Chronic Myeloid Leukemia, from Pathophysiology to Treatment-Free Remission: A Narrative Literature Review

Chronic myeloid leukemia (CML) is one of the most common leukemias occurring in the adult population. The course of CML is divided into three phases: the chronic phase, the acceleration phase, and the blast phase. Pathophysiology of CML revolves around Philadelphia chromosome that constitutively activate tyrosine kinase through BCR-ABL1 oncoprotein. In the era of tyrosine kinase inhibitors (TKIs), CML patients now have a similar life expectancy to people without CML, and it is now very rare for CML patients to progress to the blast phase. Only a small proportion of CML patients have resistance to TKI, caused by BCR-ABL1 point mutations. CML patients with TKI resistance should be treated with second or third generation TKI, depending on the BCR-ABL1 mutation. Recently, many studies have shown that it is possible for CML patients who achieve a long-term deep molecular response to stop TKIs treatment and maintain remission. This review aimed to provide an overview of CML, including its pathophysiology, clinical manifestations, the role of stem cells, CML treatments, and treatment-free remission.

A Systematic Review on Second Treatment-Free Remission (TFR) Attempt in Chronic Myeloid Leukemia (CML): Can it be Applied in Clinical Practice?

The prognosis and life expectancy of chronic myeloid leukemia (CML) patients have improved significantly with the launch of first tyrosine kinase inhibitor (TKI), imatinib. Maintaining at least one major molecular response in CML patients without the use of TKI is known as treatment-free remission (TFR). The safety of the first TFR (TFR1) effort has been reported by numerous studies. However, some patients relapse during TFR1. A second TFR (TFR2) can be tried again in those patients. This systematic review aims to evaluate individual patient characteristics for a TFR2, factors predicting successful TFR2, monitoring, consequences of the cessation of TKI, and studies about TFR2. We identified 5 studies related TFR2. The results showed that the first failed TKI discontinuation attempt is not an indicator of a second TKI discontinuation failure. TKIs could safely and successfully be discontinued for a second time in chronic phase CML patients despite a TFR1 failure. The most important factors for estimating TFR2 success are the speed of molecular relapse and the TKI-free duration after the first TKI discontinuation attempt. New trends in the management of CML patients are reducing the side effects of treatment, lessening the financial burden, and improving the quality of life of patients as CML has developed into a manageable chronic disease rather than an aggressive cancer. Although there are many studies and guidelines on TFR1, there are few studies on TFR2 and predictive factors. More data is still needed regarding TFR2 attempt in patients with CML.

Cross-Domain Text Mining to Predict Adverse Events from Tyrosine Kinase Inhibitors for Chronic Myeloid Leukemia

Tyrosine kinase inhibitors (TKIs) are prescribed for chronic myeloid leukemia (CML) and some other cancers. The objective was to predict and rank TKI-related adverse events (AEs), including under-reported or preclinical AEs, using novel text mining. First, k-means clustering of 2575 clinical CML TKI abstracts separated TKIs by significant (p < 0.05) AE type: gastrointestinal (bosutinib); edema (imatinib); pulmonary (dasatinib); diabetes (nilotinib); cardiovascular (ponatinib). Next, we propose a novel cross-domain text mining method utilizing a knowledge graph, link prediction, and hub node network analysis to predict new relationships. Cross-domain text mining of 30+ million articles via SemNet predicted and ranked known and novel TKI AEs. Three physiology-based tiers were formed using unsupervised rank aggregation feature importance. Tier 1 ranked in the top 1%: hematology (anemia, neutropenia, thrombocytopenia, hypocellular marrow); glucose (diabetes, insulin resistance, metabolic syndrome); iron (deficiency, overload, metabolism), cardiovascular (hypertension, heart failure, vascular dilation); thyroid (hypothyroidism, hyperthyroidism, parathyroid). Tier 2 ranked in the top 5%: inflammation (chronic inflammatory disorder, autoimmune, periodontitis); kidney (glomerulonephritis, glomerulopathy, toxic nephropathy). Tier 3 ranked in the top 10%: gastrointestinal (bowel regulation, hepatitis, pancreatitis); neuromuscular (autonomia, neuropathy, muscle pain); others (secondary cancers, vitamin deficiency, edema). Results suggest proactive TKI patient AE surveillance levels: regular surveillance for tier 1, infrequent surveillance for tier 2, and symptom-based surveillance for tier 3.

Digital Droplet PCR in Hematologic Malignancies: A New Useful Molecular Tool

Digital droplet PCR (ddPCR) is a recent version of quantitative PCR (QT-PCR), useful for measuring gene expression, doing clonality assays and detecting hot spot mutations. In respect of QT-PCR, ddPCR is more sensitive, does not need any reference curve and can quantify one quarter of samples already defined as "positive but not quantifiable". In the IgH and TCR clonality assessment, ddPCR recapitulates the allele-specific oligonucleotide PCR (ASO-PCR), being not adapt for detecting clonal evolution, that, on the contrary, does not represent a pitfall for the next generation sequencing (NGS) technique. Differently from NGS, ddPCR is not able to sequence the whole gene, but it is useful, cheaper, and less time-consuming when hot spot mutations are the targets, such as occurs with IDH1, IDH2, NPM1 in acute leukemias or T315I mutation in Philadelphia-positive leukemias or JAK2 in chronic myeloproliferative neoplasms. Further versions of ddPCR, that combine different primers/probes fluorescences and concentrations, allow measuring up to four targets in the same PCR reaction, sparing material, time, and money. ddPCR is also useful for quantitating BCR-ABL1 fusion gene, WT1 expression, donor chimerism, and minimal residual disease, so helping physicians to realize that "patient-tailored therapy" that is the aim of the modern hematology.