Incidence and clinical importance of BCR-ABL1 mutations in Iranian patients with chronic myeloid leukemia on imatinib

Association of SLC22A1,SLCO1B3 Drug Transporter Polymorphisms and Smoking with Disease Risk and Cytogenetic Response to Imatinib in Patients with Chronic Myeloid Leukemia

OBJECTIVE

To determine whether polymorphisms of SLC22A1 and SLCO1B3 genes could predict imatinib (IM) response and chronic myeloid leukemia (CML) risk.

METHODS

We genotyped SLC22A1 (c.480G > C, c.1222A > G) and SLCO1B3 (c.334T > G, c.699G > A) polymorphisms in 132 patients with CML and 109 sex- and age-matched healthy subjects. The patients were evaluated for cytogenetic response by standard chromosome banding analysis (CBA).

RESULTS

Polymorphism analysis showed significant increased risk of IM resistance for SLC22A1c.1222AG (P = .03; OR = 2.2), SLCO1B3c.334TT/TG genotypes (P = .007; OR = 4.37) and 334T allele (P = .03; OR = 2.86). The double combinations of SLC22A1c.480CC and c.1222AG polymorphisms with SLCO1B3c.334TT/TG were significantly associated with complete cytogenetic response (CCyR) (P <.05; OR> 7). The interaction between all polymorphisms and smoking were associated with CML development and IM resistance (P ≤.04; OR> 3).

CONCLUSIONS

Our study results suggest the influence of SLC22A1 and SLCO1B3 polymorphisms and the interaction of smoking on CML development and IM response.

Imatinib Efficacy, Safety and Resistance in Iranian Patients with Chronic Myeloid Leukemia: A Review of Literature

Background: Imatinib is the gold standard in the treatment of chronic myeloid leukemia (CML) patients. Resistance to imatinib is interfering with patients’ responses and their survivals.

Materials and Methods: We designed a systematic search to find relevant studies by applying appropriate keywords in PubMed, Web of science, Scopus, Ovid, ProQuest, Science direct and Google scholar for English studies. We also investigated the aforementioned terms’ correspondence in Magiran, Scientific information database (SID) and Google scholar for Persian articles.

Results: 25 studies were selected for final analysis. Reported hematologic responses from adult studies ranged 86-99% and major molecular responses were estimated in 38.84% of our patients within 12 months of treatment. The most frequent reported adverse drug reactions (ADRs) were edema (n=5 studies, 100%) and fatigue and nausea (n=4 studies, 80%); ADR per capita ratio was 1.46. Only one study informed ADRs in pediatrics demonstrating 93% of patients experienced ADRs after receiving imatinib. Most of the Studies (n=4, 67% from 7 studies) considered BCR/ABL point mutation as main reason of imatinib resistance. Drug-binding site and P-loop regions were two common sites for BCR/ABL point mutation.

Conclusion: Imatinib as the first line treatment for CML has been associated with proper and durable responses in Iranian adults and children CML patients. Moreover, Imatinib life-threatening adverse effects were reported uncommon. Various responses to modified regimens have been reported in resistant patients; therefore, individualized treatment based on mutation type could be recommended.

Glutathione S-transferase gene polymorphic sequence variations: Association with risk and response to Imatinib among Chronic Myeloid Leukemia patients of Kashmir

INTRODUCTION

Glutathione S-transferase (GST) gene deletion or polymorphic sequence variations lead to decreased enzyme activity that influences susceptibility and response to tyrosine kinase inhibitors in chronic myeloid leukemia (CML). We aimed to analyze relation of different GST gene sequence variants with susceptibility and response to Imatinib in CML.

MATERIAL AND METHODS

A total of 150 CML cases and equal number of age and gender matched healthy controls were genotyped for five GST polymorphisms by multiplex-PCR and PCR-RFLP techniques. BCR-ABL1 transcripts were quantified by quantitative Real Time PCR (qRT-PCR).

RESULTS

GSTT1, GSTO1, and GSTO2 SNPs revealed no association, while as GSTM1_null genotype was observed to protect against the development of CML (OR = 0.53, P = .01). GSTP1 variant genotypes AG (OR = 2.1, P = .003) and GG (OR = 5.6, P < .001), significantly associated with increased risk of CML. Combined genotype analysis showed protective impact of GSTT1_present /GSTM1_null (OR = 0.44, P = .003) while as GSTT1_present /GSTP1-GG (OR = 6.92, P < .001) and GSTM1_present /GSTP1-GG (OR = 6.33, P < .001), significantly increased CML risk. GSTM1_null genotype individually and in combination with GSTT1_present associated with superior rate of major molecular response (MMR) and event free survival (EFS) (log-rank P = .029). GSTO2-AG+GG genotype associated with significantly inferior MMR rates at 3, 6, and 12 months. Also, patients with GSTO2-GG genotype showed significantly reduced EFS (log-rank P = .025). Multivariate analysis confirmed GSTM1_null as a better (HR:0.19, P = .029) and GSTO2-GG genotype as an independent poor prognostic factor (HR:2.29, P = .037).

CONCLUSION

GSTM1_null genotype seems to have a better prognostic role while GSTP1 variants significantly increase CML risk. Also, results support a correlation between disease outcome and GSTO2 polymorphism.

ABL Kinase Domain Mutations in Iranian Chronic Myeloid Leukemia Patients with Resistance to Tyrosine Kinase Inhibitors

OBJECTIVE

Tyrosine kinase inhibitors (TKIs) are considered standard first-line treatment in patients with chronic myeloid leukemia. Because ABL kinase domain mutations are the most common causes of treatment resistance, their prevalence and assessment during treatment may predict subsequent response to therapy.

METHODS

The molecular response in Bcr-Abl1IS was tested via quantitative real-time polymerase chain reaction. We used the direct sequencing technique to discover the mutations in the ABL kinase domain. The IRIS trial established a standard baseline for measurement - (100% BCR-ABL1 on the 'international scale') and a major molecular response (good response to therapy) was defined as a 3-log reduction in the amount of BCR-ABL1 - 0.1% BCR-ABL1 on the international scale.

RESULTS

We observed 11 different mutations in 13 patients, including E255K, which had the highest mutation rate. A lack of hematologic response was found in 22 patients, who showed a significantly higher incidence of mutations.

CONCLUSION

Detection of kinase domain mutations is a reliable method for choosing the best treatment strategy based on patients' conditions, avoiding ineffective treatments, and running high-cost protocols in patients with acquired resistance to TKIs.

Influence of glutathione S-transferases (GSTM1, GSTT1, and GSTP1) genetic polymorphisms and smoking on susceptibility risk of chronic myeloid leukemia and treatment response

Background

Glutathione S‐transferases (GSTs) polymorphisms may impact on chronic myeloid leukemia (CML) risk or heterogeneous responses to Imatinib mesylate (IM). The aim of this study was to evaluate the correlation between GSTs polymorphisms and CML risk, treatment response.

Methods

We genotyped GSTM1, GSTT1 null deletion polymorphisms, and GSTP1 Ile105Val polymorphism by PCR methods and BCR‐ABL transcripts were analyzed by qRT‐PCR in 104 CML patients and 104 sex‐ and age‐matched healthy individuals.

Results

Individual analysis showed significant association of GSTM1 (p = 0.008; OR = 0.46; 95% CI: 0.26–0.82) and GSTP1 genes (p = 0.04; OR = 1.56; 95% CI: 1.016–2.423) with CML risk. The combined analysis indicated that GSTM1 null/GSTT1 present, GSTM1‐null/GSTP1M*(AG/GG) as well as GSTT1 present/ GSTP1M* genotype were associated with CML risk (ORg(‐):2.28; 95% CI: 1.29–4.04; ORgg: 2.85; 95% CI: 1.36–5.97; OR(‐)g: 1.75; 95% CI: 0.99–3.06, respectively). The proportion of CML cancer attributable to the interaction of smoking and GSTM1 null, GSTT1null, and GSTP1 M* was 42%, 39%, and 13%, respectively. Patients with GSTM1‐null and GSTP1 AG/GG genotype had significantly a lower rate of MMR achievement (p = 0.00; p = 0.009 respectively). Event‐free survival (EFS) percentage was similar between GSTM1 null and GSTM1 present patients (p = 0.21).

Conclusion

Our study suggests the influence of GSTM1 and GSTP1 polymorphisms on CML risk and treatment response. The interaction between GSTs polymorphisms and smoking plays a significant role on CML susceptibility.