Therapy for patients with chronic phase-chronic myeloid leukemia previously treated with ⩾2 tyrosine kinase inhibitors: a systematic literature review

Background

ATP-competitive tyrosine kinase inhibitors (TKIs) are the current standard of care for patients with chronic phase-chronic myeloid leukemia (CP-CML) in the first-line and second-line (2 L) setting. Treatment after 2 L is not clearly established.

Objective

The objective of this study was to summarize the available evidence to compare the efficacy and safety of interventions in the treatment of CP-CML patients who had received ⩾2 prior TKIs.

Design

A systematic literature review was performed.

Data source and methods

A systematic literature review (SLR) of studies published until May 2021, reporting clinical outcomes in adult patients with CP-CML who had received ⩾ 2 prior TKIs was performed. Studies were identified through the database searches via Ovid platform (Embase, MEDLINE Epub Ahead of Print, In-Process and Other Non-Indexed Citations, and Cochrane Central Register of Controlled Trials), the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP), bibliographic search of relevant reviews, and proceedings from the previous 3 years of the key conferences in the field of oncology.

Results

Our search identified 38 relevant studies. Among the identified studies of the current third-line treatments, the major molecular response (MMR) rate for ponatinib was 19.0-66.7%, 23.3-25.5% for asciminib, 19.2% for omacetaxine, and 13.2% for bosutinib at 6 months. The complete cytogenetic response (CCyR) rate was 21.4-64.8% for ponatinib, 38.7-40.8% for asciminib, 18-24.2% for bosutinib, and 16.1% for omacetaxine at 6 months.

Conclusion

The findings from current SLR demonstrated the lack of data for patients with CML treated with ⩾2 TKIs. TKIs such as asciminib, ponatinib, and bosutinib are valid options for those patients. Further research is needed to identify the best treatment option for patients with CML receiving later lines of therapy.

Effect of asciminib and vitamin K2 on Abelson tyrosine-kinase-inhibitor-resistant chronic myelogenous leukemia cells

BACKGROUND

Abelson (ABL) tyrosine kinase inhibitors (TKIs) are effective against chronic myeloid leukemia (CML); however, many patients develop resistance during ABL TKI therapy. Vitamin K2 (VK2) is a crucial fat-soluble vitamin used to activate hepatic coagulation factors and treat osteoporosis. Although VK2 has demonstrated impressive anticancer activity in various cancer cell lines, it is not known whether VK2 enhances the effects of asciminib, which specifically targets the ABL myristoyl pocket (STAMP) inhibitor.

METHOD

In this work, we investigated whether VK2 contributed to the development of CML cell lines. We also investigated the efficacy of asciminib and VK2 by using K562, ponatinib-resistant K562 (K562 PR), Ba/F3 BCR-ABL, and T315I point mutant Ba/F3 (Ba/F3 T315I) cells.

RESULTS

Based on data from the Gene Expression Omnibus (GEO) database, gamma-glutamyl carboxylase (GGCX) and vitamin K epoxide reductase complex subunit 1 (VKORC1) were elevated in imatinib-resistant patients (GSE130404). UBIA Prenyltransferase Domain Containing 1 (UBIAD1) was decreased, and K562 PR cells were resistant to ponatinib. In contrast, asciminib inhibited CML cells and ponatinib resistance in a dose-dependent manner. CML cells were suppressed by VK2. Caspase 3/7 activity was also elevated, as was cellular cytotoxicity. Asciminib plus VK2 therapy induced a significantly higher level of cytotoxicity than use of each drug alone. Asciminib and VK2 therapy altered the mitochondrial membrane potential.

CONCLUSIONS

Asciminib and VK2 are suggested as a novel treatment for ABL-TKI-resistant cells since they increase treatment efficacy. Additionally, this treatment option has intriguing clinical relevance for patients who are resistant to ABL TKIs.

[Next treatment for TKI-resistant CML]

Tyrosine kinase inhibitors (TKIs) have significantly improved the prognosis of chronic myeloid leukemia (CML) in the chronic phase. However, only 50-60% of patients stay on the same TKI for 5 years, and the long-term progression-free survival rate is significantly reduced if an early molecular response is not achieved. Possible mechanisms of therapeutic resistance against BCR::ABL1 dependent clones include point mutations in the ABL1 kinase domain, BCR::ABL1 splicing variants, BCR::ABL1 overexpression, and altered pharmacokinetics by the ABC transporter. Ponatinib, the most potent inhibitor among TKIs, and the STAMP inhibitor asciminib are important drugs for overcoming BCR::ABL1-dependent resistance.

An evaluation of asciminib for patients with chronic myeloid leukemia previously treated with ≥2 Tyrosine Kinase Inhibitors

INTRODUCTION

: To date, five tyrosine kinase inhibitors (TKIs) are available for treating chronic myeloid leukemia (CML) patients in clinical practice. Despite this, a significant proportion of patients will ultimately develop failure to approved TKIs due to intolerance or resistance. Consequently, new treatment approaches are still required in this unmet clinical need. Asciminib, a first-in-class BCR::ABL1 inhibitor Specifically Targeting the ABL Myristoyl Pocket (STAMP), has the potential to overcome resistance/intolerance to prior TKI treatment.

AREAS COVERED

This review will cover the mechanism of action, pharmacokinetic profile and clinical data of asciminib based on available information from laboratory studies, clinical trials and real world evidence.

EXPERT OPINION

Recent approval of asciminib will require positioning of this drug in the treatment algorithm of CML patients failing initial TKI therapy. Available data support the lack of cross-intolerance of asciminib with other TKIs and its favorable cardiovascular toxicity profile. In addition, asciminib has demonstrated considerable efficacy in CML patients who have failed at least two TKIs, although preliminary data suggest that this efficacy may be lower in those previously exposed to ponatinib. The introduction of asciminib in clinical practice may represent an important step forward in the management of CML.

Pharmacokinetics of Asciminib in Individuals With Hepatic or Renal Impairment

Asciminib is an investigational, first-in-class, specifically targeting the ABL myristoyl pocket (STAMP) inhibitor of BCR-ABL1 with a new mechanism of action compared with approved ATP-competitive tyrosine kinase inhibitors. This report describes the findings from 2 phase 1 studies assessing the pharmacokinetic (PK) profile of a single dose of asciminib (40 mg) in individuals with impaired renal function (based on absolute glomerular filtration rate; NCT03605277) or impaired hepatic function (based on Child-Pugh classification; NCT02857868). Individuals with severe renal impairment exhibited 49%-56% higher exposure (area under the curve [AUC]), with similar maximum plasma concentration (C_max ), than matched healthy controls. Based on these findings, as per the protocol, the PK of asciminib in individuals with mild or moderate renal impairment was not assessed. In individuals with mild and severe hepatic impairment, asciminib AUC was 21%-22% and 55%-66% higher, respectively, and C_max was 26% and 29% higher, respectively, compared with individuals with normal hepatic function. Individuals with moderate hepatic impairment had similar asciminib AUC and C_max than matched healthy controls. The increase in asciminib AUC and C_max in the mild hepatic impairment cohort was mainly driven by 1 participant with particularly high exposure. Asciminib was generally well tolerated, and the safety data were consistent with its known safety profile. In summary, these findings indicate that renal or hepatic impairment has no clinically meaningful effect on the exposure or safety profile of asciminib, and support its use in patients with varying degrees of renal or hepatic dysfunction.