Questions concerning tyrosine kinase-inhibitor therapy and transplants in chronic phase chronic myeloid leukaemia

Haematopoietic stem cell transplantation after reduced intensity conditioning in children and adolescents with chronic myeloid leukaemia: A prospective multicentre trial of the I-BFM Study Group

This prospective multicentre trial evaluated the safety and the efficacy of a thiotepa/melphalan-based reduced intensity conditioning (RIC) haematopoietic stem cell transplantation (HSCT) in children and adolescents with chronic myeloid leukaemia (CML) in chronic phase (CP). Thirty-two patients were transplanted from matched siblings or matched unrelated donors. In 22 patients, HSCT was performed due to insufficient molecular response or loss of response to first- or second-generation tyrosine kinase inhibitor (TKI), with pretransplant BCR::ABL1 transcripts ranging between 0.001% and 33%. The protocol included a BCR::ABL1-guided intervention with TKI retreatment in the first year and donor lymphocyte infusions (DLI) in the second-year post-transplant. All patients engrafted. The 1-year transplant-related mortality was 3% (confidence interval [CI]: 0%-6%). After a median follow-up of 6.3 years, 5-year overall survival and event-free survival are 97% (CI: 93%-100%) and 91% (CI: 79%-100%) respectively. The current 5-year leukaemia-free survival with BCR::ABL1 <0.01% is 97% (CI: 88%-100%) and the current TKI- and DLI-free survival is 95% (CI: 85%-100%). The incidence of chronic graft-versus-host disease (GvHD) was 32%, being severe in four patients (13%). At last follow-up, 31 patients are GvHD-free and have stopped immunosuppression. RIC HSCT following pretreatment with TKI is feasible and effective in children and adolescents with CP-CML with an excellent disease-free and TKI-free survival.

Successful maintenance of a sustained molecular response in CML patients receiving low-dose tyrosine kinase inhibitors

Background

The development of tyrosine kinase inhibitor (TKI) therapy has positively impacted the survival rates of patients with chronic myeloid leukemia (CML). It is common in medical practice to adjust the dosage of TKI downward because of TKI-associated adverse events, financial burden, comorbidity, or an attempt at treatment-free remission.

Objectives

This investigation sought to explore the feasibility of employing a reduced dosage of TKI for treating CML.

Design

This was a retrospective study.

Methods

Patients with CML in its chronic phase who had been on a reduced dose of TKI for a minimum of 3 months for various reasons in a practical clinical environment, irrespective of molecular response, were included. Regular molecular monitoring was performed, and changes in adverse events were recorded after dose reduction.

Results

This research included a total of 144 participants. Upon reducing the dosage, 136 of 144 patients achieved major molecular response or deeper, and 132 of 144 achieved molecular response 4 (MR4). Following a median observation period of 16 months, the calculated 1- and 2-year survival rates free from MR4 failure were estimated to be 96.5% (95% CI: 90.8-98.7) and 90.5% (95% CI: 81.3-95.3), respectively. MR4 failure-free survival was better in patients with longer MR4 durations (⩾34 months) before dose reduction (p = 0.02). The median interval from dose reduction to MR4 loss was 15 months. Improved TKI-associated adverse events after dose reduction were observed in 61.3% of patients.

Conclusion

Lowering the TKI dose can effectively preserve a deep molecular response over time while relieving adverse events caused by TKIs.

Chronic myeloid leukaemia: Biology and therapy

Chronic myeloid leukaemia (CML) is caused by BCR::ABL1. Tyrosine kinase-inhibitors (TKIs) are the initial therapy. Several organizations have reported milestones to evaluate response to initial TKI-therapy and suggest when a change of TKI should be considered. Achieving treatment-free remission (TFR) is increasingly recognized as the optimal therapy goal. Which TKI is the best initial therapy for which persons and what depth and duration of molecular remission is needed to achieve TFR are controversial. In this review we discuss these issues and suggest future research directions.

Real-world experience with ponatinib therapy in chronic phase chronic myeloid leukemia: impact of depth of response on survival and prior exposure to nilotinib on arterial occlusive events

We surveyed the performance of ponatinib, as salvage therapy, in a real-world setting of chronic phase chronic myeloid leukemia (CML-CP). Among 55 consecutive patients (median age 49 years) with relapsed/refractory CML-CP, 35 (64%) had failed ≥3 tyrosine kinase inhibitors (TKIs), 35 (64%) were pre-treated with nilotinib, and 14 (28%) harbored ABL1T315I. At start of ponatinib (median dose 30 mg/day), 40 patients were already in complete hematologic (CHR), 4 in complete cytogenetic (CCyR), 3 in major molecular (MMR) remission, while 8 had not achieved CHR (NR). Ponatinib improved the depth of response in 13 (33%), 3 (75%), 2 (66%), and 4 (50%) patients with CHR, CCyR, MMR, and NR, respectively (p = 0.02). At a median follow-up of 42 months, 13 (23%) deaths, 5 (9%) blast transformations, and 25 (45%) allogeneic transplants were recorded. Five/10-year post-ponatinib survival was 77%/58% with no significant difference when patients were stratified by allogeneic transplant (p = 0.94), ponatinib-induced deeper response (p = 0.28), or a post-ponatinib ≥CCyR vs CHR remission state (p = 0.25). ABL1T315I was detrimental to survival (p = 0.04) but did not appear to affect response. Prior exposure to nilotinib was associated with higher risk of arterial occlusive events (AOEs; 11% vs 0%; age-adjusted p = 0.04). Ponatinib starting/maintenance dose (45 vs 15 mg/day) did not influence either treatment response or AOEs. Our observations support the use of a lower starting/maintenance dose for ponatinib in relapsed/refractory CML-CP but a survival advantage for deeper responses was not apparent and treatment might not overcome the detrimental impact of ABL1T315I on survival. The association between prior exposure to nilotinib and a higher risk of post-ponatinib AOEs requires further validation.

Quality-of-life, mental health, and perspective on TKI dose reduction as a prelude to discontinuation in chronic phase chronic myeloid leukemia

BACKGROUND

Treatment-free remission (TFR) has become the main target for chronic myeloid leukemia (CML). Tyrosine kinase inhibitors (TKI) dose optimization is crucial in managing adverse events, and improving adherence in clinical practice. In persons achieving a deep molecular response (DMR), some data suggest TKI dose reduction before discontinuation does not change success rate of achieving TFR, but this is controversial. However, data on quality-of-life (QoL) and mental health in CML patients with full-dose TKI, low-dose TKI, and TKI discontinuation are limited. Moreover, recent evidence indicating the feasibility of TKI dose reduction and discontinuation after dose reduction, which may change CML patients' perspectives on TKI discontinuation.

METHODS

We conducted a cross-sectional study using online questionnaires to explore the QoL, mental health in patients with diverse TKI dose, and perspective on TKI dose reduction as a prelude to discontinuation.

RESULTS

1450 responses were included in the analysis. 44.3% of respondents reported a moderate-to-severe impact of TKI treatment on their QoL. 17% of respondents had moderate-to-severe anxiety. 24.4% of respondents had moderate-to-severe depression. In 1326 patients who had not discontinued their medication, 1055 (79.6%) patients reported they would try TKI discontinuation because of concerns over side effects of long-term medication (67.9%), financial burden (68.7%), poor QoL (77.9%), pregnancy needs (11.6%), anxiety and depression while taking TKI (20.8%), inconvenience of TKI treatment (22.2%). 613 of 817 (75.0%) patients on full-dose TKI therapy indicated they preferred trying a dose reduction before discontinuing TKI therapy after dose reduction compared with 31 (3.8%) preferring no dose reduction before stopping.

CONCLUSIONS

TKI dose reduction showed a significant improvement of patients' QoL and mental health, comparable to the effect of TKI discontinuation. Most patients indicated they preferred dose reduction before stopping TKI therapy. In clinical practice, TKI dose reduction can be considered as a bridge from full-dose treatment to discontinuation. Our results showed that tyrosine kinase inhibitors (TKI) dose reduction showed a significant improvement of patients' quality-of-life and mental health, comparable to the effect of TKI discontinuation. Most patients desire to discontinue TKI in the future. TKI discontinuation after dose reduction is more acceptable compared to discontinuing it directly. In clinical practice, TKI dose reduction can be considered as a bridge from full-dose treatment to discontinuation. Please do not hesitate to contact me in case further clarification is needed with this submission.

Evaluation of physician guideline adherence and areas for improvement in managing patients with chronic myeloid leukemia: a cross-sectional survey

The experience of a physician at a clinical center is among the critical factors in managing chronic myeloid leukemia (CML) during its treatment with tyrosine kinase inhibitors (TKIs). The authors conducted a cross-sectional questionnaire to investigate barriers to physician use of published evidence-based guidelines in CML management in a real-world setting. Among the participating physicians (N = 407), 99.8% of physicians reported that CML guidelines were useful; however, only 62.9% of physicians reported that they follow guidelines in real-time. Although 90.7% of physicians prefer second-generation TKIs as the first-line treatment, imatinib (88.2%) remains the most widely administered TKI in the first-line setting. Only 50.6% of physicians switched the treatment when patients failed to achieve early molecular response (at 3 months), whereas 70.3% of physicians switched the treatment when patients' response to TKI was inadequate at 6 months and/or 12 months. Moreover, only 43.5% of physicians considered treatment-free remission (TFR) as one of the top 3 goals for their patients. The major concern to obtain TFR was patients' adherence. This study demonstrated that CML management was generally in line with the current guidelines, but some of the details at the point of care are needed to be improved in CML.

Jak2/STAT6/c-Myc pathway is vital to the pathogenicity of Philadelphia-positive acute lymphoblastic leukemia caused by P190BCR-ABL

BACKGROUND

The Philadelphia chromosome encodes the BCR-ABL fusion protein, which has two primary subtypes, P210 and P190. P210 and P190 cause Philadelphia-positive chronic myeloid leukemia (Ph+ CML) and Philadelphia-positive acute lymphoblastic leukemia (Ph+ ALL), respectively. The Ph+ ALL is more malignant than Ph+ CML in disease phenotype and progression. This implies the key pathogenic molecules and regulatory mechanisms caused by BCR-ABL in two types of leukemia are different. It is reported that STAT6 was significantly activated only in P190 transformed cells. However, the potential role and the mechanism of STAT6 activation in Ph+ ALL and its activation mechanism by P190 are still unknown.

METHODS

The protein and mRNA levels of STAT6, c-Myc, and other molecules were measured by western blot and quantitative real-time PCR. The STAT6 inhibitor AS1517499 was used to specifically inhibit p-STAT6. The effect of p-STAT6 inhibition on Ph+ CML and Ph+ ALL cells was identified by CCK-8 and FCM assay. Dual luciferase reporter and ChIP assay were performed to confirm the direct binding between STAT6 and c-Myc. The impact of STAT6 inhibition on tumor progression was detected in Ph+ CML and Ph+ ALL mouse models.

RESULTS

Our results demonstrated that P210 induced CML-like disease, and P190 caused the more malignant ALL-like disease in mouse models. STAT6 was activated in P190 cell lines but not in P210 cell lines. Inhibition of STAT6 suppressed the malignancy of Ph+ ALL in vitro and in vivo, whereas it had little effect on Ph+ CML. We confirmed that p-STAT6 regulated the transcription of c-Myc, and STAT6 was phosphorylated by p-Jak2 in P190 cell lines, which accounted for the discrepant expression of p-STAT6 in P190 and P210 cell lines. STAT6 inhibition synergized with imatinib in Ph+ ALL cells.

CONCLUSIONS

Our study suggests that STAT6 activation plays an essential role in the development of Ph+ ALL and may be a potential therapeutic target in Ph+ ALL. Video abstract.