Bosutinib: Valuable therapeutic option for the Bulgarian market

Aim of Study: This review aims to highlight that bosutinib represents a valuable alternative for patients already treated unsuccessfully with one or more other tyrosine kinase inhibitors (TKIs). Chronic myelogenous leukemia (CML) is a myeloproliferative neoplasm associated with a specific genetic abnormality resulting in a fusion protein with an active tyrosine kinase region. Therefore, TKIs were developed as a suitable treatment option. Methods: Full-text articles, abstracts, and meta-analysis comparing the efficacy and safety of the five TKIs were included in the review. Efficacy of these enhanced therapies is estimated on the basis of achievement of a complete cytogenetic response (CCyR) and this outcome is an important goal as a surrogate marker for improved survival. Results: Bosutinib's efficacy is comparable to that of imatinib in the first-line setting and with dasatinib and nilotinib as second-line therapy, while its safety profile is distinctly different. Most therapeutic guidelines for CML recommend an initiation of therapy with imatinib and application of dasatinib and nilotinib as subsequent lines. Conclusion: Bosutinib is generally not recommended despite its demonstrated efficacy and manageable toxicity. However, resistance, intolerance, specific mutations, as well as disease progression are often the reasons for the lack of sufficient response to therapy registered by the lower rates or complete absence of CCyR. Treatment options are limited for these patients.