Differential prognostic impact of stratified additional chromosome abnormalities on disease progression among Malaysian chronic myeloid leukemia patients undergoing treatment with imatinib mesylate.

The emergence of additional chromosome abnormalities (ACAs) in chronic myeloid leukemia (CML) patients during treatment with a tyrosine kinase inhibitor (TKI) regime is generally associated with resistance to treatment and a sign of disease progression to accelerated phase or blast phase. We report the type, frequency, and differential prognostic impact of stratified ACAs with treatment response in 251 Malaysian CML patients undergoing TKI therapy. ACAs were observed in 40 patients (15.9%) of which 7 patients (17.5%) showed ACAs at time of initial diagnosis whereas 33 patients (82.5%) showed ACAs during the course of IM treatment. In order to assess the prognostic significance, we stratified the CML patients with ACAs into four groups, group 1 (+8/+Ph), group 2 (hypodiploidy), group 3 (structural/complex abnormalities); group 4 (high-risk complex abnormalities), and followed up the disease outcome of patients. Group 1 and group 2 relatively showed good prognosis while patients in group 3 and group 4 had progressed or transformed to AP or blast phase with a median survival rate of 12 months after progression. Novel ACAs consisting of rearrangements involving chromosome 11 and chromosome 12 were found to lead to myeloid BP while ACAs involving the deletion of 7q or monosomy 7 led toward a lymphoid blast phase. There was no evidence of group 2 abnormalities (hypodiploidy) contributing to disease progression. Compared to group 1 abnormalities, CML patients with group 3 and group 4 abnormalities showed a higher risk for disease progression. We conclude that the stratification based on individual ACAs has a differential prognostic impact and might be a potential novel risk predictive system to prognosticate and guide the treatment of CML patients at diagnosis and during treatment.

Application of HRM Analysis in Detection of PDGFRA Exon 10 Polymorphism in CML Patients with Imatinib Resistance

@#Introduction: Imatinib mesylate has been widely used as a standard treatment for chronic myeloid leukemia (CML). It acts as a selective competitive inhibitor of the BCR-ABL tyrosine kinase. Despite the excellent efficacy on CML treatment, some patients developed resistance to the treatment. Mutation in the PDGFRA may be one of the factors involved in the mechanism of resistance that affects the response to imatinib. The mutational status of PDGFRA is highly relevant for prognosis and treatment prediction in CML patients. Thus, this study is intended to establish and validate a High Resolution Melting (HRM) analysis for PDGFRA exon 10 c.1432 T>C polymorphism in CML patients. Methods: High resolution melting (HRM) analysis was used to identify the c.1432 T > C polymorphism in PDGFRA exon 10 (n =86; response = 43; resistance = 43). The results from HRM analysis were compared and validated with Sanger sequencing. The association between the polymorphism and treatment response was assessed by statistical analysis using binomial logistic regression analysis. Results: HRM analyses showed two different melt curves. One curve followed the shape of the reference, homozygous wild type (TT) and the other curve showed a different melting profile than the reference with the TC genotype (heterozygous variant). The results revealed that heterozygous variant (TC) genotype showed a high risk of acquiring resistance with an OR of 3.795; 95% CI: 1.502-9.591, with a statistically significant association, p = 0.005. HRM analysis also showed 100% sensitivity and specificity in the detection of PDGFRA exon 10. Conclusion: The HRM analysis of PDGFRA exon 10 c.1432 T>C was successfully established. The exon 10 c.1432 T>C polymorphism shows a higher risk for the development of resistance toward imatinib treatment.

Commemorating the 40-Year Journey of the School of Medical Sciences, Universiti Sains Malaysia

@#The School of Medical Sciences of Universiti Sains Malaysia (USM) is the launching pad for this journal. From the school’s humble beginning at the USM Main Campus in Pulau Pinang, Malaysia, it has grown in stature at its current location in the USM Health Campus, Kubang Kerian, Kelantan, Malaysia. Commemorating its 40th anniversary, this editorial aims to recollect, although not exhaustively, the wealth of returns for the USM, as well as for the nation, which the school has managed to deliver in that period. Resolute to its vision and mission, this article highlights the outstanding accomplishments in various core aspects of the school’s academic, research and professional growth as we continually strive to train globally competitive and compassionate medical graduates, medical specialists and scientists, skilled to serve nation’s needs and broader markets worldwide. Currently guided by the Malaysian Higher Education Blueprint (2015–2025), the school shall remain ingenious in its duties in the many more years to come, as we head for a world-class trajectory.

Potential use of cord blood for Hb E hemoglobinopathy screening programme using capillary electrophoresis

Background: Thalassemia and hemoglobinopathies are inherited red blood cell disorders found worldwide. Hemoglobin (Hb) E disorder is one of the hemoglobinopathies known to have the high prevalence in South East Asia. Most of transfusion-dependent thalassemias were genotypically compound heterozygous Hb E/ β-thalassemia. In Malaysia, the national screening program for thalassemia was implemented for early pregnancy or secondary school girls; however many participants do not turn-up and missed the screening test. Screening for thalassemia using samples from cord blood is an alternative choice as it is a readily available source of blood and hence early detection of the disease. The purpose of this study was to determine the potential use of cord blood for the screening of HbE hemoglobinopathy by using capillary electrophoresis (CE). Methods: Cord blood samples were collected from 300 newborns of healthy mothers. Hematological parameters were determined and hemoglobin quantitation for all cord blood samples were performed using capillary electrophoresis system (CES) and high performance liquid chromatography (HPLC). Results: Majority of cord blood samples (63%) revealed Hb AF followed by Hb AFA2 (20%). Hb AFE was detected in 10.7% with the mean value of Hb E ranging from 2.3%-11.1%. Conclusion: Hemoglobin E was detected in cord blood using capillary electrophoresis system. It can be recommended in areas where Hb E/β is prevalent. Implementation of a screening strategy using CE on cord blood sampling will identify the disease early. With regular follow-up on these patients, the status of their disease can be determined earlier and appropriate management implemented.

Association of genotypes and haplotypes of multi-drug transporter genes ABCB1 and ABCG2 with clinical response to imatinib mesylate in chronic myeloid leukemia patients.

The introduction and success of imatinib mesylate (IM) has become a paradigm shift in chronic myeloid leukemia (CML) treatment. However, the high efficacy of IM has been hampered by the issue of clinical resistance that might due to pharmacogenetic variability. In the current study, the contribution of three common single nucleotide polymorphisms (SNPs) of ABCB1 (T1236C, G2677T/A and C3435T) and two SNPs of ABCG2 (G34A and C421A) genes in mediating resistance and/or good response among 215 CML patients on IM therapy were investigated. Among these patients, the frequency distribution of ABCG2 421 CC, CA and AA genotypes were significantly different between IM good response and resistant groups (P=0.01). Resistance was significantly associated with patients who had homozygous ABCB1 1236 CC genotype with OR 2.79 (95%CI: 1.217-6.374, P=0.01). For ABCB1 G2677T/A polymorphism, a better complete cytogenetic remission was observed for patients with variant TT/AT/AA genotype, compared to other genotype groups (OR=0.48, 95%CI: 0.239-0.957, P=0.03). Haplotype analysis revealed that ABCB1 haplotypes (C1236G2677C3435) was statistically linked to higher risk to IM resistance (25.8% vs. 17.4%, P=0.04), while ABCG2 diplotype A34A421 was significantly correlated with IM good response (9.1% vs. 3.9%, P=0.03). In addition, genotypic variant in ABCG2 421C>A was associated with a major molecular response (MMR) (OR=2.20, 95%CI: 1.273-3.811, P=0.004), whereas ABCB1 2677G>T/A variant was associated with a significantly lower molecular response (OR=0.49, 95%CI: 0.248-0.974, P=0.04). However, there was no significant correlation of these SNPs with IM intolerance and IM induced hepatotoxicity. Our results suggest the usefulness of genotyping of these single nucleotide polymorphisms in predicting IM response among CML patients.

BCR-ABL kinase domain mutations, including 2 novel mutations in imatinib resistant Malaysian chronic myeloid leukemia patients-Frequency and clinical outcome.

Discovery of imatinib mesylate (IM) as the targeted BCR-ABL protein tyrosine kinase inhibitor (TKI) has resulted in its use as the frontline therapy for chronic myeloid leukemia (CML) across the world. Although high response rates are observed in CML patients who receive IM treatment, a significant number of patients develop resistance to IM. Resistance to IM in patients has been associated with a heterogeneous array of mechanisms of which point mutations within the ABL tyrosine kinase domain (TKD) are the frequently documented. The types and frequencies of mutations reported in different population studies have shown wide variability. We screened 125 Malaysian CML patients on IM therapy who showed either TKI refractory or resistance to IM to investigate the frequency and pattern of BCR-ABL kinase domain mutations among Malaysian CML patients undergoing IM therapy and to determine the clinical significance. Mutational screening using denaturing high performance liquid chromatography (dHPLC) followed by DNA sequencing was performed on 125 IM resistant Malaysian CML patients. Mutations were detected in 28 patients (22.4%). Fifteen different types of mutations (T315I, E255K, G250E, M351T, F359C, G251E, Y253H, V289F, E355G, N368S, L387M, H369R, A397P, E355A, D276G), including 2 novel mutations were identified, with T315I as the predominant type of mutation. The data generated from clinical and molecular parameters studied were correlated with the survival of CML patients. Patients with Y253H, M351T and E355G TKD mutations showed poorer prognosis compared to those without mutation. Interestingly, when the prognostic impact of the observed mutations was compared inter-individually, E355G and Y253H mutations were associated with more adverse prognosis and shorter survival (P=0.025 and 0.005 respectively) than T315I mutation. Results suggest that apart from those mutations occurring in the three crucial regions (catalytic domain, P-loop and activation-loop), other rare mutations also may have high impact in the development of resistance and adverse prognosis. Presence of mutations in different regions of BCR-ABL TKD leads to different levels of resistance and early detection of emerging mutant clones may help in decision making for alternative treatment. Serial monitoring of BCR-ABL1 transcripts in CML patients allows appropriate selection of CML patients for BCR-ABL1 KD mutation analysis associated with acquired TKI resistance. Identification of these KD mutations is essential in order to direct alternative treatments in such CML patients.