Facultad de Ciencias de la Salud

Introduction: The main goal of treatment in cancer patients is to achieve the highest therapeutic effectiveness with the least iatrogenic toxicity. Tyrosine kinase inhibitors (TKIs) are anticancer oral agents, usually administered at fixed doses, which present high inter- and intraindividual variability due to their pharmacokinetic characteristics. Therapeutic drug monitoring (TDM) can be used to optimize the use of several types of medication. Objective: We evaluated the use of TDM of TKIs in routine clinical practice through studying the variability in exposure to erlotinib, imatinib, lapatinib, and sorafenib and dose adjustment. Materials and methods: We conducted a retrospective analytical study involving patients who received treatment with TKIs, guided by TDM and with subsequent recommendation of dose adjustment. The quantification of the plasma levels of the different drugs was performed using high-performance liquid chromatography (HPLC). The Clinical Research Ethics Committee of the Hospital Quirónsalud Torrevieja approved this study. Results: The inter-individual variability in the first cycle and in the last monitored cycle was 46.2% and 44.0% for erlotinib, 48.9 and 50.8% for imatinib, 60.7% and 56.0% for lapatinib and 89.7% and 72.5% for sorafenib. Relationships between exposure and baseline characteristics for erlotinib, imatinib, lapatinib and sorafenib were not statistically significant for any of the variables evaluated (weight, height, body surface area (BSA), age and sex). Relationships between height (p = 0.021) and BSA (p = 0.022) were statistically significant for sorafenib. No significant relationships were observed between Ctrough and progression-free survival (PFS) or overall survival (OS) for any drug, except in the case of sunitinib (correlation between Ctrough and PFS p = 0.023) in the exposure–efficacy analysis. Conclusions: Erlotinib, imatinib, lapatinib and sorafenib show large inter-individual variability in exposure. TDM entails a significant improvement in exposure and enables more effective and safe use of TKIs in routine clinical practice.

La leucemia aguda linfoblástica (LAL) es una enfermedad linfoproliferativa caracterizada por la presencia de alteraciones cromosómicas y mutaciones que hacen de esta enfermedad una de las principales causas de mortalidad dentro de las neoplasias hematológicas. El Imatinib (IM) forma parte integral de la terapia de primera línea en leucemias Ph+ al ser un inhibidor específico de Bcr-Abl. Sin embargo, en LAL-B Ph+ resulta muy poco efectivo al expresarse la oncoproteína Bcr-Abl p190. Por otra parte, resultados previos de nuestro grupo demuestran que Bcr-Abl induce la degradación proteasomal del inhibidor del ciclo celular p27kip1, y la no degradación de esta proteína es suficiente para detener la progresión del ciclo celular. Además, las células que expresan Bcr-Abl son más sensibles a la inducción de apoptosis por la inhibición del proteasoma con Bortezomib (Btz) que células que no expresan dicha oncoproteína. Asimismo, el Btz es capaz de detener el crecimiento celular e inducir la apoptosis en células de LAL-T al inhibir la expresión de genes diana de Notch1. Por todo ello, en este trabajo hemos explorado el uso del inhibidor del proteasoma Btz en células de leucemia aguda linfoblástica, tanto de células B con cromosoma Philadelphia (LAL-B Ph+) como de células T (LAL-T), demostrando que este inhibidor causa parada de ciclo celular e induce apoptosis por activación de la ruta de las caspasas. Además el Btz induce una menor expresión del gen antiapoptótico Bcl-2, así como una expresión diferencial de los genes pro-supervivencia y pro-apoptoticos entre las líneas celulares estudiadas que se correlaciona directamente con la diferente sensibilidad al Btz. También, hemos visto que la resistencia al Btz tiene una relación directa con una mayor expresión del proteasoma constitutivo. Finalmente, analizamos el efecto combinado de IM y Btz en células de LAL-B Ph+ y descubrimos que el IM aumenta la sensibilidad al Btz, de tal forma que la administración secuencial del IM seguido del Btz produce un efecto sinérgico mayor que si se administran de manera conjunta los dos fármacos. Con nuestros resultados proponemos el uso del Btz para inducir apoptosis en células de LAL, especialmente cuando hay mayor expresión del inmunoproteasoma, y la administración consecutiva de IM seguido de Btz para mejorar el tratamiento de leucemias Bcr-Abl positivas. Acute Lymphoblastic Leukemia (ALL) is a lymphoproliferative disease characterized by the presence of chromosomal abnormalities and mutations that make this disease one of the leading causes of death in hematological malignancies. Imatinib (IM) has become an integral part of front-line therapy for Ph+ leukemias being a specific inhibitor of Bcr-Abl. However, it has proven to be far less efficacious in the treatment of ALL-B Ph+ expressing the p190 form of Bcr-Abl. Previous results of our group suggest that Bcr-Abl regulates proteasomal degradation of the cell-cycle inhibitor p27kip1, and the no degradation of this protein is sufficient to induce a cell-cycle arrest. In addition, Bcr-Abl-expressing cells are more sensitive to apoptosis induction by the proteasome inhibitor Bortezomib (Btz) than cells no expressing Bcr-Abl. Thus, Btz induces a cell-cycle arrest and also apoptosis in Bcr-Abl-expressing cells and not in control cells. In this study we focused on the use of the proteasome inhibitor Btz in B-cell Philadelphia chromosome positive and T-cell Acute Lymphoblastic Leukemia (ALL-B Ph+ and ALL-T) cell lines. Our results showed that Btz induced cell-cycle arrest and caspase-dependent apoptosis. Furthermore, Btz significantly induced the down-regulation of the anti-apoptotic protein BCL-2 and a differential expression of pro- and anti-apoptotic proteins between the cell lines tested, which correlated with sensitivity to Btz treatment. In line with that, we also found an increased expression of the constitutive proteasome in the Btz less sensitive cell lines. Finally, we explored the possible synergistic effects between Btz and IM in ALL-B Ph+ cell lines. We observed that IM increases the sensitivity to Btz and that the administration of IM followed by Btz produces a synergistic effect greater than when the two drugs were administrated at the same time. Based on our results we propose that Btz induces apoptosis in ALL cell lines, especially in those with an increased expression of the immunoproteasome. We also propose a sequential administration of IM followed by Btz to improve the treatment in patients with Bcr-Abl-positive leukemias.