Sarcomatoid-variant renal cell carcinoma: treatment outcome and survival in advanced disease

OBJECTIVES

Sarcomatoid variant is a spindle cell phenotype of renal cell carcinoma (RCC), which is associated with a poor prognosis. We reviewed outcomes of systemic therapy for metastatic, sarcomatoid-variant RCC.

METHODS

Clinical features, treatment outcome, and survival were evaluated in 63 patients with sarcomatoid-variant metastatic RCC (47 clear cell, 16 nonclear cell). Initial systemic treatment included antiangiogenesis-targeted therapy (n=34), cytokines (n=20), and chemotherapy (n=9).

RESULTS

Five of 63 patients (8%) achieved an objective response to the first systemic treatment: 1 (5%) to cytokine and 4 (12%) to sunitinib-targeted therapy. Median progression-free survival for 63 patients was 3 months (95% confidence interval), and median overall survival was 10 months (95% confidence interval). The median progression-free survival for patients treated with sunitinib versus all others was 4.4 months versus 2 months (P=0.03), and 3 months for patients with clear-cell histology versus 1.6 months for nonclear-cell histology (P=0.004).

CONCLUSIONS

Metastatic sarcomatoid-variant RCC was associated with a poor response to systemic therapy. Sunitinib treatment resulted in a modest response rate, but studies to characterize the underlying tumor biology of sarcomatoid-variant RCC, to assess outcome to targeted agents, and to develop novel treatment strategies are warranted.

Sunitinib: a novel tyrosine kinase inhibitor. A brief review of its therapeutic potential in the treatment of renal carcinoma and gastrointestinal stromal tumors (GIST)

Sunitinib malate is a novel oral multitargeted tyrosine kinase inhibitor with antitumor and antiangiogenic activities. Sunitinib was recently approved in first-line treatment for patients with advanced renal cell carcinoma (RCC) and for the treatment of patients with gastrointestinal stromal tumors (GIST) after disease progression or intolerance to imatinib mesylate therapy. We report the very interesting results of the phase II trials after cytokin failure and of the randomized recent trial of sunitinib versus cytokin-based therapy in first-line treatment for patients with metastatic RCC, as well as the promising results of the recent trials on patients with GIST after disease progression or intolerance to imatinib mesylate therapy. Oral sunitinib demonstrates a high level of efficacy with acceptable tolerability with the 50 mg daily for 4 weeks followed by 2 weeks off schedule; a continuous schedule could be of interest. Hypertension and asthenia are the most common side effects with sunitinib. Regardless of these encouraging results, studies investigating sunitinib in first-line treatment (for patients with GIST), adjuvant and neoadjuvant settings are awaited, as well as trials using sunitinb in combination with chemotherapy or other targeted therapies. Clinical trials investigating sunitinib in other tumor types are ongoing.

Sunitinib: from rational design to clinical efficacy

Sunitinib (SU011248) is an oral small molecular tyrosine kinase inhibitor that exhibits potent antiangiogenic and antitumor activity. Tyrosine kinase inhibitors such as SU6668 and SU5416 (semaxanib) demonstrated poor pharmacologic properties and limited efficacy; therefore, sunitinib was rationally designed and chosen for its high bioavailability and its nanomolar-range potency against the antiangiogenic receptor tyrosine kinases (RTKs)--vascular endothelial growth factor receptor (VEGFR) and platelet-derived growth factor receptor (PDGFR). Sunitinib inhibits other tyrosine kinases including, KIT, FLT3, colony-stimulating factor 1 (CSF-1), and RET, which are involved in a number of malignancies including small-cell lung cancer, GI stromal tumors (GISTs), breast cancer, acute myelogenous leukemia, multiple endocrine neoplasia types 2A and 2B, and familial medullary thyroid carcinoma. Sunitinib demonstrated robust antitumor activity in preclinical studies resulting not only in tumor growth inhibition, but tumor regression in models of colon cancer, non-small-cell lung cancer, melanoma, renal carcinoma, and squamous cell carcinoma, which were associated with inhibition of VEGFR and PDGFR phosphorylation. Clinical activity was demonstrated in neuroendocrine, colon, and breast cancers in phase II studies, whereas definitive efficacy has been demonstrated in advanced renal cell carcinoma and in imatinib-refractory GISTs, leading to US Food and Drug Administration approval of sunitinib for treatment of these two diseases. Studies investigating sunitinib alone in various tumor types and in combination with chemotherapy are ongoing. The clinical benchmarking of this small-molecule inhibitor of members of the split-kinase domain family of RTKs will lead to additional insights regarding the biology, potential biomarkers, and clinical utility of agents that target multiple signaling pathways in tumor, stromal, and endothelial compartments.