Treatment-free remission after first-line dasatinib discontinuation in patients with chronic myeloid leukaemia (first-line DADI trial): a single-arm, multicentre, phase 2 trial

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.

Incidences of Deep Molecular Responses and Treatment-Free Remission in de Novo CP-CML Patients

Simple Summary

Tyrosine kinase inhibitors (TKI) can be safely discontinued in chronic myeloid leukemia patients. Achieving a sustained deep molecular response (DMR) before stop is recommended. Currently, the proportion of patients who achieve a sustained DMR remains to be determined. Based on the follow-up of 398 patients over a ten-years period, we evaluate that 46% of them have achieved a sustained DMR. Gender, BCR-ABL1 transcript type, and disease risk scores were significantly associated with the probability of achieving a DMR. 95/398 (24%) patients stopped TKI with a probability of maintaining molecular reponse without TKI resumption of 47% at 48 months after stop. In this study, TKI duration before stop and second (nilotinib, dasatinib, bosutinib) generation frontline TKI compared to imatinib were significantly associated with a lower risk of molecular relapse after stop in patients who have achieved a sustained DMR.

Abstract

Background: Tyrosine Kinase Inhibitors (TKIs) discontinuation in patients who had achieved a deep molecular response (DMR) offer now the opportunity of prolonged treatment-free remission (TFR). Patients and Methods: Aims of this study were to evaluate the proportion of de novo chronic-phase chronic myeloid leukemia (CP-CML) patients who achieved a sustained DMR and to identify predictive factors of DMR and molecular recurrence-free survival (MRFS) after TKI discontinuation. Results: Over a period of 10 years, 398 CP-CML patients treated with first-line TKIs were included. Median age at diagnosis was 61 years, 291 (73%) and 107 (27%) patients were treated with frontline imatinib (IMA) or second- or third-generation TKIs (2–3G TKI), respectively. With a median follow-up of seven years (range, 0.6 to 13.8 years), 182 (46%) patients achieved a sustained DMR at least 24 months. Gender, BCR-ABL1 transcript type, and Sokal and ELTS risk scores were significantly associated with a higher probability of sustained DMR while TKI first-line (IMA vs. 2–3G TKI) was not. We estimate that 28% of CML-CP would have been an optimal candidate for TKI discontinuation according to recent recommendations. Finally, 95 (24%) patients have entered in a TFR program. MRFS rates at 12 and 48 months were 55.1% (95% CI, 44.3% to 65.9%) and 46.9% (95% CI, 34.9% to 58.9%), respectively. In multivariate analyses, first-line 2–3G TKIs compared to IMA and TKI duration were the most significant factors of MRFS. Conclusions: Our results suggest that frontline TKIs have a significant impact on TFR in patients who fulfill the selection criteria for TKI discontinuation.

Surrogate Markers for Treatment-Free Remission in Patients With Chronic Myeloid Leukemia

BCR-ABL1 tyrosine kinase inhibitors (TKIs) improve long-term survival of patients with chronic-phase (CP) chronic myeloid leukemia (CML). Recently, the treatment goal for patients with CML-CP became safe discontinuation of TKIs. Several clinical trials have shown that approximately half of patients who experience a durable deep molecular response during TKI treatment maintain molecular remission after discontinuation of TKIs. However, the factors responsible for successful treatment-free remission (TFR) remain unclear. This study reviews very recent TKI discontinuation studies, focusing on factors responsible for TFR in patients with CML-CP. Longer TKI treatment duration, time of deep molecular response, presence of withdrawal syndrome, deeper molecular response, lower Sokal score, interferon α treatment before TKI administration, and favorable natural killer or T-cell profiles may be associated with TFR. However, different study designs have generated inconsistent data. Further investigations are needed to identify factors that consistently favor achievement of TFR.

Silent NK/T cell reactions to dasatinib during sustained deep molecular response before cessation are associated with longer treatment-free remission

This study presents the final report of the multicenter, prospective tyrosine kinase inhibitor discontinuation study, D-STOP, after a 3-year follow-up of 54 patients with chronic CML who discontinued dasatinib after a sustained deep molecular response (DMR) for ≥2 years with dasatinib treatment. Estimated treatment-free remission (TFR) rates at 12 and 36 months were 63.0% [95% confidence interval (CI): 48.7-74.3] and 59.3% (95% CI: 45.0-71.0), respectively. CD3^- CD56⁺ NK, CD16⁺ CD56⁺ NK, and CD57⁺ CD56⁺ NK large granular lymphocyte (NK-LGL), CD8⁺ CD4^- cytotoxic T cell, and CD57⁺ CD3⁺ T-LGL cell numbers were relatively elevated throughout the 24-month consolidation only in failed patients who molecularly relapsed within 12 months. In successful patients, these subsets elevated transiently after 12 months, but returned to basal levels after 24-month consolidation. Therefore, smaller changes in NK/T, particularly the NK subset throughout consolidation, reflected higher TFR rates. TFR rates of those patients exhibiting elevation in CD3^- CD56⁺ NK >376 cells/μL, CD16⁺ CD56⁺ NK > 241 cells/μL, or CD57⁺ CD56⁺ NK-LGL >242 cells/μL during consolidation compared with others were 26.7% (8.3%-49.6%) vs 78.3% (55.4%-90.3%), HR 0.032 (0.0027-0.38; P = .0064), 31.2% (11.4%-53.6%) vs 85.0% (60.4%-94.9%), HR 0.039 (0.0031-0.48; P = .011), or 36.8% (16.5%-57.5%) vs 77.3% (53.7%-89.8%), HR 0.21 (0.065-0.69; P = .010), respectively. Therefore, silent responses of T/NK subsets to dasatinib throughout consolidation were significant for longer TFR. Elevated NK/T, particularly NK lymphocytes responsive to dasatinib, may be immunologically insufficient to maintain TFR. Their decline, subsequently replaced by altered lymphocyte population with less response to dasatinib during sustained DMR, might be immunologically significant. (D-STOP, NCT01627132).

Chronic Myeloid Leukemia Prognosis and Therapy: Criticisms and Perspectives

Ph+ chronic myeloid leukemia (CML) is a clonal myeloproliferative disease whose clinical course is characterized by progression disease from the early chronic phase (CP) to the fatal blastic phase (BP). This programmed course is closely related to the translocation t(9;22)(q22;q11) and the resulting BCR-ABL1 fusion protein (p210) that drives the leukemic transformation of hematopoietic stem cells. Therefore, the cure of CML can only pass through the abrogation of the Ph+ clone. Allogeneic stem cell transplantation (allo-SCT) and interferon-alpha (IFNα) have been proven to reduce the Ph+ clone in a limited proportion of CML population and this translated in a lower rate of progression to BP and in a significant prolongation of survival. Tyrosine-kinase inhibitors (TKIs), lastly introduced in 2000, by preventing the disease blastic transformation and significantly prolonging the survival in up to 90% of the patient population, radically changed the fate of CML. The current therapy with TKIs induces a chronicization of the disease but several criticisms still persist, and the most relevant one is the sustainability of long-term therapy with TKIs in terms of compliance, toxicity and costs. The perspectives concern the optimization of therapy according to the age, the risk of disease, the potency and the safety profiles of the TKIs. The prolongation of survival is the most important end point which should be guaranteed to all patients. The treatment free remission (TFR) is the new goal that we would like to give to an increasing number of patients. The cure remains the main objective of CML therapy.

Budget impact analysis of treatment-free remission in nilotinib-treated Japanese chronic myeloid leukemia patients

Treatment‐free remission (TFR), in which patients discontinue pharmacotherapy and remain in molecular remission, is an emerging treatment goal for patients with chronic myeloid leukemia (CML). Attainment of TFR requires an increased frequency of molecular monitoring, to ensure that patients maintain a deep molecular response. The objective of this analysis was to assess the economic impact of stopping nilotinib among Japanese TFR‐eligible patients. A Markov model evaluated the economic impact of TFR among the study population, TFR‐eligible CML patients diagnosed since 2012. The model compared patients who had discontinued tyrosine kinase inhibitor (TKI) treatment (ie, attempted TFR) with patients that continued TKI treatment. A 3‐y time horizon was modeled from a Japanese public payer perspective. Costs associated with drug treatment, hospital/physician visits, and molecular monitoring were considered. TFR‐eligible patients were calculated from Japanese CML incidence rates and efficacy was derived from nilotinib trials. Japanese co‐payment maximums were utilized to assess the patient perspective. An estimated 761 and 140 patients were eligible for first‐ and second‐line nilotinib, respectively, in 2019. Assuming that 100% of eligible patients complied, TFR was associated with cost savings of ¥7 625 174 640 (US$66 567 775) over 3 y. In scenarios with reduced willingness to attempt TFR, cost savings persisted. Achievement of TFR was estimated to markedly reduce out‐of‐pocket expenses for CML patients, regardless of the timing of relapse. Stopping nilotinib for TFR‐eligible patients in Japan may result in significant cost savings to both payers and patients. Monitoring costs contributed little to overall annual costs and decreased over time.

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.