Circulating protein biomarkers of pharmacodynamic activity of sunitinib in patients with metastatic renal cell carcinoma: modulation of VEGF and VEGF-related proteins

Surgical resection of isolated retroperitoneal lymph node recurrence of renal cell carcinoma following nephrectomy

PURPOSE

Durable survival has been reported following the resection of solitary metachronous metastasis of renal cell carcinoma at sites including the lung, bone and adrenal. We report our experience with resection of isolated retroperitoneal lymph node recurrence.

MATERIALS AND METHODS

Patients who underwent surgical resection of isolated metachronous recurrence of renal cell carcinoma in the retroperitoneal lymph nodes following radical nephrectomy for pT(any)N(any)M0 tumors were identified (group 1). Progression-free and cancer specific survival were estimated using the Kaplan-Meier method and compared to survival in patients who had pT(any)N+M0 disease at nephrectomy (group 2) and in patients who underwent complete resection of a solitary metachronous metastasis at other sites (group 3).

RESULTS

A total of 15 patients underwent resection of isolated retroperitoneal lymph node recurrence of renal cell carcinoma. Median time from nephrectomy to resection was 10.3 months (range 3 to 159). No patient received systemic therapy before resection. Recurrence was asymptomatic in all except 1 patient. No intraoperative or postoperative mortality occurred. Six patients subsequently died of renal cell carcinoma at a median of 18 months (range 6 to 33.6) following resection. Median progression-free survival in groups 1 to 3 was 9.1, 8.7 and 15.6 months, while median cancer specific survival was 33.3, 20.8 and 46.9 months, respectively.

CONCLUSIONS

Resection of isolated retroperitoneal lymph node recurrence may be associated with survival rates approaching those of resection of solitary metastasis at other sites. The decreased time to progression relative to patients with resected metastasis at other sites likely reflects the aggressive biology of nodal disease.

Phase II Study of Sunitinib Malate, an Oral Multitargeted Tyrosine Kinase Inhibitor, in Patients With Metastatic Breast Cancer Previously Treated With an Anthracycline and a Taxane

Purpose

Sunitinib is an oral, multitargeted tyrosine kinase inhibitor that inhibits vascular endothelial growth factor receptor (VEGFR), platelet-derived growth factor receptor, stem cell factor receptor (KIT), and colony-stimulating factor-1 receptor. This phase II, open-label, multicenter study evaluated sunitinib monotherapy in patients with metastatic breast cancer (MBC).

Patients and Methods

Sixty-four patients previously treated with an anthracycline and a taxane received sunitinib 50 mg/d in 6-week cycles (4 weeks on, then 2 weeks off treatment). The primary end point was objective response rate. Plasma samples were obtained for pharmacokinetic and biomarker analysis.

Results

Seven patients achieved a partial response (median duration, 19 weeks), giving an overall response rate of 11%. Three additional patients (5%) maintained stable disease for ≥ 6 months. Median time to progression and overall survival were 10 and 38 weeks, respectively. Notably, responses occurred in triple negative tumors and HER2-positive, trastuzumab-treated patients. Thirty-three patients (52%) required dose interruption during ≥ 1 cycle, and 25 patients required dose reduction (39%). Thirty-six patients (56%) had dose modifications due to adverse events (AEs). Treatment was associated with increases in plasma VEGF and decreases in soluble VEGFRs and KIT. The most common AEs were fatigue, nausea, diarrhea, mucosal inflammation, and anorexia. Most AEs were mild to moderate (grade 1 to 2) in severity and were effectively managed with dose delays or reductions.

Conclusion

Sunitinib is active in patients with heavily pretreated MBC. Most AEs were of mild-to-moderate severity and manageable with supportive treatment and/or dose modification. Further studies in breast cancer are warranted.

Predicting outcome to VEGF-targeted therapy in metastatic clear-cell renal cell carcinoma: data from recent studies

Attempts to predict outcome in patients with metastatic clear-cell renal cell carcinoma (RCC) have conventionally been based on pretherapy clinical factors such as performance status, disease-free interval, number of metastatic sites and several laboratory variables. These factors were developed before the era of VEGF-targeted therapy. Recent analysis from trials with anti-VEGF agents indicate that these factors continue to be of major importance in patient prognostication. Additionally, several serum and molecular markers, many of which relate to certain alterations of the von Hippel-Lindau pathway, are currently being investigated. Responses to VEGF-targeted agents appear to be related to a greater modulation of serum VEGF and soluble VEGF receptor levels. The impact of von Hippel-Lindau gene status on response to VEGF-targeted therapy was tested in a large study and was not found to predict a higher response rate to these agents. However, a subset of von Hippel-Lindau mutations that predict a 'loss of function' of the von Hippel-Lindau gene seem to have the best response to these agents. Future prognostic models will incorporate molecular markers with clinical variables to refine prognosis and prediction in metastatic clear-cell RCC patients treated with novel VEGF-targeted agents. These models, if externally and prospectively validated, will culminate in the rational selection of patients for specific VEGF-directed therapeutics.

Vascular endothelial growth factor-mediated decrease in plasma soluble vascular endothelial growth factor receptor-2 levels as a surrogate biomarker for tumor growth

Vascular endothelial growth factor (VEGF) is a potent proangiogenic protein that activates VEGF receptor (VEGFR) tyrosine kinases expressed by vascular endothelial cells. We previously showed that one of these receptors, VEGFR-2, has a truncated soluble form (sVEGFR-2) that can be detected in mouse and human plasma. Because activation of VEGFR-2 plays an important role in tumor angiogenesis, clinical interest in monitoring plasma sVEGFR-2 levels in cancer patients has focused on its potential exploitation as a surrogate biomarker for disease progression as well as assessing efficacy/activity of antiangiogenic drugs, particularly those that target VEGF or VEGFR-2. However, no preclinical studies have been done to study sVEGFR-2 during tumor growth or the mechanisms involved in its modulation. Using spontaneously growing tumors and both localized and metastatic human tumor xenografts, we evaluated the relationship between sVEGFR-2 and tumor burden as well as underlying factors governing protein level modulation in vivo. Our results show an inverse relationship between the levels of sVEGFR-2 and tumor size. Furthermore, using various methods of VEGF overexpression in vivo, including cell transfection and adenoviral delivery, we found plasma sVEGFR-2 decreases to be mediated largely by tumor-derived VEGF. Finally, in vitro studies indicate VEGF-mediated sVEGFR-2 modulation is the result of ligand-induced down-regulation of the VEGFR-2 from the cell surface. Taken together, these findings may be pertinent to further clinical exploitation of plasma sVEGFR-2 levels as a surrogate biomarker of VEGF-dependent tumor growth as well as an activity indicator of antiangiogenic drugs that target the VEGFR system.