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Aim: The present study aimed to conduct a series of meta-analyses to investigate the influence of imatinib trough concentration (C0), as well as ABCB1 and ABCG2 polymorphisms, on the clinical response in patients with chronic myeloid leukemia (CML). Methods: A literature search was conducted using the PubMed and Cochrane electronic databases to locate relevant papers from 2003 onward. Then, an initial meta-analysis of 14 studies involving 2184 patients was conducted to understand the effect of imatinib mesylate (IM) C0 on clinical outcome in CML patients. Subsequently, a series of meta-analyses were performed, including up to 23 studies with 2577 patients, on the effect of genetic polymorphisms of ABCB1 and ABCG2 on the clinical response to IM. Results: Meta-analysis revealed that patients who achieved a major molecular response (MMR) have a significantly higher IM C0 than those who failed to achieve an MMR. We also found that the patients who achieved a complete cytogenic response (CCyR) have a significantly higher IM C0 than those who did not achieve a CCyR. However, no significant difference in IM C0 was found between the complete molecular response and non-complete molecular response groups. Additional analysis showed that ABCG2 421 variant A allele was significantly associated with a higher rate of MMR and overall response, especially in Asian patients. Meta-analysis did not reveal a correlation between ABCB1 C3435T and C1236T polymorphisms with any clinical response to IM. However, the G2677T/A polymorphism could play a role in IM response in the recessive model. Conclusion: This meta-analysis demonstrates that there was a significant correlation between the IM trough concentration and clinical responses, especially MMR and CCyR, in CML patients. Furthermore, we found that the probability of successful treatment was correlated with the ABCG2 C421A polymorphism, at least within the Asian population. We failed to determine an association between ABCB1 polymorphisms and IM response, although the G2677T/A polymorphism might be involved. However, further large-scale investigations using more sensitive genotyping methods would be required to confirm this.

MicroRNAs are a class of short noncoding RNAs, that play a relevant role in multiple biological processes, such as differentiation, proliferation and apoptosis. Gastrointestinal stromal tumors (GIST) are considered as a paradigm of molecular biology in solid tumors worldwide, and after the discovery of specific alterations in the KIT and PDGFRA genes, they have emerged from anonymity to become a model for targeted therapy. Epigenetics have an emerging and relevant role in different steps of GIST biology such as tumorigenesis, disease progression, prognosis and drug resistance. The aim of the present review was to summarize the current evidence about the role of microRNAs in GIST, including their potential application as well as their limits.

Gastrointestinal stromal tumor (GIST) is a well-recognized and now relatively well-understood mesenchymal tumor. Before the imatinib era, the treatment of metastatic GIST was frustrating owing to its refractoriness to conventional chemotherapy and radiotherapy. After a metastatic GIST patient was granted compassionate use of imatinib in 2000, the treatment of this disease has emerged as a model for the development of other molecularly targeted therapies. In this article the authors review how tumor genotypes, in particular KIT and PDGFRA mutational analysis, have been integrated in the optimal clinical management of GIST patients. The authors also discuss the potential practical relevance of pharmacogenetics, which, integrated with therapeutic drug monitoring, should receive greater consideration, with the aim of personalized therapy.