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    Abstract:
    Sunitinib is considered a first-line therapeutic option for patients with advanced clear cell renal cell carcinoma (ccRCC). Despite sunitinib's clinical efficacy, patients eventually develop drug resistance and disease progression. Herein, we tested the hypothesis whether initial sunitinib resistance may be transient and could be overcome by dose increase. In selected patients initially treated with 50 mg sunitinib and presenting with minimal toxicities, sunitinib dose was escalated to 62.5 mg and/or 75 mg at the time of tumor progression. Mice bearing two different patient-derived ccRCC xenografts (PDX) were treated 5 days per week with a dose-escalation schema (40-60-80 mg/kg sunitinib). Tumor tissues were collected before dose increments for immunohistochemistry analyses and drug levels. Selected intrapatient sunitinib dose escalation was safe and several patients had added progression-free survival. In parallel, our preclinical results showed that PDXs, although initially responsive to sunitinib at 40 mg/kg, eventually developed resistance. When the dose was incrementally increased, again we observed tumor response to sunitinib. A resistant phenotype was associated with transient increase of tumor vasculature despite intratumor sunitinib accumulation at higher dose. In addition, we observed associated changes in the expression of the methyltransferase EZH2 and histone marks at the time of resistance. Furthermore, specific EZH2 inhibition resulted in increased in vitro antitumor effect of sunitinib. Overall, our results suggest that initial sunitinib-induced resistance may be overcome, in part, by increasing the dose, and highlight the potential role of epigenetic changes associated with sunitinib resistance that can represent new targets for therapeutic intervention.
    Keywords:
    Acquired resistance
    Transient (computer programming)
    Sunitinib is an oral multitargeted tyrosine kinase inhibitor with antiangiogenic properties used for treatment of renal cell carcinoma and gastrointestinal stromal tumors at a dose of 50 mg/day consecutively for 4 weeks followed by 2 weeks off per cycle. At present, no data are available on the early prediction of sunitinib response in renal cell carcinoma. We report a clinical case of a patient with metastatic renal cell carcinoma diagnosed with 11 C-acetate PET and conventional CT and treated with sunitinib. Partial and complete remission documented by CT was preceded by early functional tumor inhibition shown by 11 C-acetate-PET after only 14 days of therapy. This case report highlights some interesting points related to the potential role of a novel non-FDG PET tracer, 11 C-acetate, in the early prediction of the response to targeted therapies in metastatic renal cell carcinoma.
    Citations (29)
    This chapter summarizes the findings of one of the earliest trials of targeted therapy with a protein kinase inhibitor in patients with previously untreated, metastatic renal cell carcinoma who received either systemic sunitinib or interferon alfa. The study found better progression-free survival and overall survival in patients who received sunitinib. Diarrhea was the most common adverse event in the sunitinib group and was much more frequent compared to the interferon alfa group
    Interferon alfa
    Renal cell carcinoma(RCC) has three characteristics including high metastatic,prone to relapse and resistant to conventional chemotherapy.And immunotherapy is just efficiency to minority patients.With the development of the molecular biology of RCC,research of targeting therapy of the metastatic RCC has developed quickly.Sunitinib which is one of the molecular targeting agents has made a great efficacy in RCC.But we should pay more attention on its adverse reactions and complications.
    Targeted Therapy
    Kidney cancer
    Citations (0)
    Concerns have been raised about possible theoretical risk of thrombosis and bleeding with sunitinib (anti-vascular endothelial cell growth factor agent) therapy used for treatment of metastatic renal cell carcinoma. We present the first case of stroke in an older man with metastatic renal cell carcinoma, on sunitinib therapy.
    Stroke
    Citations (6)
    Renal cell carcinoma (RCC) is responsible for 4% of all neoplasms in adults and for 80% of all primary renal tumors. Metastatic RCC is resistant to all cytotoxic agents and generally prognosis is poor. However, the clinical behavior of RCC is unpredictable, and late recurrences of disease can occur even after several years from the initial surgical approach, so response to the currently available targeted agents is uncertain, due to the lack of reliable prognostic and predictive factors. We report the case of a patient who developed a metastatic recurrence of RCC 16 years after primary treatment, in spite of metastatic disease at diagnosis. At the time of relapse, the disease showed a surprisingly long-term response to Sunitinib, which is maintained after 74 months of treatment. This case report highlights the unpredictable behavior of RCC and underlines the presence of a subset of patients with metastatic RCC achieving long-term response to Sunitinib, despite poor clinical features. In this subset of patients, an important clinical question arises about the appropriate duration of treatment and the need to continue it indefinitely.
    Citations (3)