Diagnosis and Monitoring of Chronic Myeloid Leukemia: Chiang Mai University Experience

Comparative Clinical Outcomes and Safety of Generic Versus Original Imatinib in the Treatment of Chronic Myeloid Leukemia: A Real-World Cohort Study from Thailand

Background/Objectives: Imatinib, a first-generation tyrosine kinase inhibitor, is the standard treatment for chronic myeloid leukemia (CML). Although generic formulations have improved access, concerns regarding their efficacy and safety remain. This study aimed to compare the clinical outcomes and adverse events of original and generic imatinib in patients with CML in Thailand. Methods: We conducted a retrospective cohort study of patients with chronic-phase CML receiving frontline imatinib at Chiang Mai University Hospital between January 2012 and September 2022. Treatment responses, event-free survival (EFS), overall survival (OS), and adverse events were also analyzed. Results: Among the 71 patients, 46 (64.8%) received original imatinib, and 25 (35.2%) received generic imatinib. The median follow-up period was 80.3 months (IQR: 52.0-106.4). At 12 months, there were no significant differences in the cumulative complete cytogenetic response (73.3% vs. 70.8%, p = 0.825) or major molecular response (35.6% vs. 41.7%, p = 0.618). Although EFS was not significantly different between the groups, OS was significantly longer in patients receiving original imatinib (p < 0.001). Conclusions: Although early treatment responses and EFS were similar, generic imatinib was associated with an inferior OS. These findings highlight the need for close monitoring and further evaluation of long-term outcomes when using generic formulations.

Practical Laboratory Tools for Monitoring of BCR-ABL1 Transcripts and Tyrosine Kinase (TK) Domain Mutations in Chronic Myeloid Leukemia Patients Undergoing TK Inhibitor Therapy: A Single-Center Experience in Thailand

Objective:

The genetic hallmark of CML is known as the appearance of t(9;22)(q34.1;q11.2) (BCR-ABL1) which is present in more than 95% of cases. Here, we demonstrated practical laboratory tools for monitoring of BCR-ABL1 transcripts in chronic myeloid leukemia patients undergoing TK inhibitor therapy.

Methods:

Real time quantitative PCR and direct sequencing were performed for monitoring of BCR-ABL1 transcripts in 245 treated CML.

Results:

At month 3 after first time point of monitoring, we found that 89% (218/245), 2% (5/245), and 9% (22/245) of patients are determined as optimal, warning, and failure response, respectively. The responses to TKI were slightly decreased at months 6 as following 73% optimal (180/245), 18% warning (43/245), and 9% failure response (22/245). Additionally, responses to TKI were gradually decreased at month 12 after first time point of monitoring as following 65% optimal (160/245), 13% warning (31/245), and 22% failure (54/245). We could detect 20% (49/245) of patients positive for BCR-ABL1 TKD mutations. Interestingly, one third (17 of 49) of TKD mutated cases were positive for compound/polyclonal mutation patterns. While major molecular response were observed in the majority of patients without TKD mutation, resistant to TKI were detected in patients with T315I mutation (n = 9; % mean IS = 8.1510, % median IS = 9.7000), compound/polyclonal mutations with T315I (n = 9; % mean IS = 13.0779, % median IS = 5.404), and other TKD mutations (n = 14; % mean IS = 8.1416, % median IS = 1.060), respectively.

Conlusion:

These practical laboratory techniques provided a more comprehensive understanding of CML progression during drug therapy and could be of benefit in earlier prognosis.

Droplet digital PCR for BCR/ABL(P210) detection of chronic myeloid leukemia: A high sensitive method of the minimal residual disease and disease progression

OBJECTIVE

This study intended to establish a droplet digital PCR (dd-PCR) for monitoring minimal residual disease (MRD) in patients with BCR/ABL (P210)-positive chronic myeloid leukemia (CML), thereby achieving deep-level monitoring of tumor load and determining the efficacy for guided clinically individualized treatment.

METHODS

Using dd-PCR and RT-qPCR, two cell suspensions were obtained from K562 cells and normal peripheral blood mononuclear cells by gradient dilution and were measured at the cellular level. At peripheral blood (PB) level, 61 cases with CML-chronic phase (CML-CP) were obtained after tyrosine kinase inhibitor (TKI) treatment and regular follow-ups. By RT-qPCR, BCR/ABL (P210) fusion gene was undetectable in PB after three successive analyses, which were performed once every 3 months. At the same time, dd-PCR was performed simultaneously with the last equal amount of cDNA. Ten CML patients with MR4.5 were followed up by the two methods.

RESULTS

At the cellular level, consistency of results of dd-PCR and RT-qPCR reached R²  ≥ 0.99, with conversion equation of Y = 33.148X^1.222 (Y: dd-PCR results; X: RT-qPCR results). In the dd-PCR test, 11 of the 61 patients with CML (18.03%) tested positive and showed statistically significant difference (P < .01). In the follow-up of 10 CML patients who were in MR4.5. All patients were loss of MR4.0, and 4 were tested positive by dd-PCR 3 months earlier than by RT-qPCR.

CONCLUSION

In contrast with RT-qPCR, dd-PCR is more sensitive, thus enabling accurate conversion of dd-PCR results into internationally standard RT-qPCR results by conversion equation, to achieve a deeper molecular biology-based stratification of BCR/ABL(P210) MRD. It has some reference value to monitor disease progression in clinic.