RESUMEN
The rearranged during transfection (RET) gene encodes a protein tyrosine kinase. RET alterations by point mutations and gene fusions were found in diverse cancers. RET fusions allow abnormal expression and activation of the oncogenic kinase, whereas only a few of RET point mutations found in human cancers are known oncogenic drivers. Earlier studies of RET-targeted therapy utilized multi-targeted protein tyrosine kinase inhibitors (TKIs) with RET inhibitor activity. These multi-targeted TKIs often led to high-grade adverse events and were subject to resistance caused by the gatekeeper mutations. Recently, two potent and selective RET TKIs, pralsetinib (BLU-667) and selpercatinib (LOXO-292), were developed. High response rates to these selective RET inhibitors across multiple forms of RET alterations in different types of cancers were observed in clinical trials, demonstrating the RET dependence in human cancers harboring these RET lesions. Pralsetinib and selpercatinib were effective in inhibiting RETV804L/M gatekeeper mutants. However, adaptive mutations that cause resistance to pralsetinib or selpercatinib at the solvent front RETG810 residue have been found, pointing to the need for the development of the next-generation of RET TKIs.
RESUMEN
Pazopanib is a protein tyrosine kinase inhibitor that limits tumor growth through angiogenesis inhibition. The use of other protein tyrosine kinase inhibitors, specifically sunitinib, within non-clear cell renal cell carcinoma (nccRCC) has led to increased survival with a decreased adverse event profile. The data for the treatment of nccRCC is limited, with most studies evaluating the use of sunitinib. Therefore, the evaluation of pazopanib is of particular clinical interest in the treatment of nccRCC. The objective of this systematic review was to assess the efficacy and safety of pazopanib for nccRCC. PubMed (1946 to April 2019) and Embase (1947 to April 2019) were queried using the search term combination: protein tyrosine kinase inhibitor or pazopanib and non clear cell renal cell carcinoma or non-clear cell renal cell carcinoma. Studies evaluating clinical outcomes of pazopanib for nccRCC were included, represented by 3 retrospective cohort studies and 1 single-arm, open-label prospective study. In patients with advanced or metastatic nccRCC, treatment with pazopanib resulted in positive effects for multiple markers of efficacy, including progression-free survival, overall survival, and objective response rates. The median duration of follow-up ranged from 11.8 months to 24.4 months. Pazopanib was well-tolerated in most studies. The most commonly reported adverse events were fatigue, diarrhea, and hypertension. Pazopanib appears to be an effective and safe option for the treatment of advanced or metastatic nccRCC. Future investigation with larger randomized controlled trials is warranted to further define the role of pazopanib in patients with nccRCC.