Expression of thymidine phosphorylase in primary human renal cell carcinoma by ELISA method

Recent aspects of sunitinib therapy in patients with metastatic clear-cell renal cell carcinoma: a systematic review of the literature

Sunitinib is an orally available inhibitor of multiple tyrosine-kinase receptors approved for the treatment of advanced clear-cell renal cell carcinoma (ccRCC), a disease which has habitually had a very poor patient survival rate. Although it has become the most widely used drug for this disease, it remains not completely clear the best treatment strategy with these agent. The aim of this review is to highlight the most recent and interesting aspects of the research on treatment of advanced ccRCC with sunitinib and eventually determine alternative treatment schedule to reduce the incidence of side effects; we also wanted to review recent biomarkers able to predict response to therapy and also to point out the mechanism of acquired resistance to this drug.

Thymidine phosphorylase as a prognostic factor in renal cell carcinoma

The purpose of the current study was to clarify further the clinicopathologic significance of thymidine phosphorylase (TP) expression in renal cell carcinoma (RCC). TP expression was evaluated with immunohistochemistry assays using monoclonal anti-TP antibody in formalin-fixed, paraffin-embedded archived specimens of 70 patients with radically operated nonmetastatic RCC (M0 by TNM classification). Semiquantitative analysis, using a scoring system for staining pattern and staining intensity was used. Univariate analysis showed that the characteristics that carried the prognostic significance for survival were age as continuous characteristic (chi-square log-rank test P = 0.0121), TP expression (P = 0.0061), histologic grade (P < 0.0001), and stage (P = 0.0244). In multivariate analysis (by Cox proportional hazards regression analysis), the factors significant for survival were age (HR 1.09; 95% CI 1.03-1.14), stage (HR 2.76; 95% CI 1.27-6.07), and histologic grade (HR 7.91; 95% CI 2.11-29.7), TP did not show independent significant value (HR 0.68; 95% CI 0.19-2.50). However, TP had strong correlation with histologic grade (P = 0.818). In conclusion, TP expression level in RCC is strongly correlated with histologic grade, which is one of well-known prognostic factors in RCC, but TP had no independent prognostic value.

Phase II trial of capecitabine and rHu-interferon-alpha-2a in patients with metastatic renal cell carcinoma, limited efficacy, and moderate toxicity

BACKGROUND

Capecitabine is an orally administered fluoropyrimidine that is converted to 5-fluorouracil by thymidine phosphorylase. In view of the recognized synergism of fluoropyrimidines with interferon-alpha (IFNalpha), a Phase II study to characterize the toxicity and efficacy of the combination of capecitabine and rHuIFNalpha-2a for the treatment of patients with renal cell carcinoma (RCC) was conducted.

PATIENTS AND METHODS

Eligible patients had metastatic RCC, measurable disease, and no prior systemic therapy. A total of 32 patients were entered into the study. Histologic subtypes included clear cell (n = 28) and nonclear cell (n = 2). Histology was unknown for 2 patients. The first 14 patients were treated with capecitabine 1,000 mg/m(2) twice daily on days 1-14 and 22-36, combined with IFNalpha-2a 3.0 MU/m(2) subcutaneously 3 times weekly. Because of toxicity requiring dose reductions during the first cycle, the capecitabine dose was reduced to 825 mg/m(2) twice daily on days 1-14 and 22-36 in the subsequent 18 patients.

RESULTS

Responses were seen in 4 of 32 patients (12%) (95% confidence interval 4% to 29%), with 1 complete response and 3 partial responses. There were 3 responses that occurred at the higher capecitabine starting dose level. Median response duration was 12 months (range 4.6-15.0). There were 12 patients (38%) who had stable disease for at least 2 cycles (duration 2.9 to 33.6+ months). One-year survival was 63%. Toxicity was moderate to severe and required dose reductions in 88% of patients. There were 23 patients who had grade > or =3 toxicity.

CONCLUSION

The combination of capecitabine and IFNalpha-2a has limited activity in metastatic RCC and is associated with moderate-to-severe toxicity.

High levels of thymidine phosphorylase as an independent prognostic factor in renal cell carcinoma

BACKGROUND

We investigated whether thymidine phosphorylase (TP) protein level in renal cell carcinoma (RCC) correlates with clinicopathological characteristics and clinical outcomes.

METHODS

TP protein level was measured in 116 RCC specimens and in 90 non-neoplastic kidney tissues using a sandwich-type enzyme-linked immunosolvent assay.

RESULTS

The median TP protein level in RCC tissues was 9.76-fold (range, 3.2-933.9) higher than those in non-neoplastic kidney tissues (P < 0.0001). TP protein level was correlated with T classification, histological grade and mode of infiltration. TP as a prognostic variable was studied using a logistic regression model. TP at higher levels (128 U/mg protein or greater) would play a role as an independent prognostic factor (odds ratio, 13.73; 95% confidence interval, 2.09-90.41; P = 0.0064).

CONCLUSION

TP at high levels can be regarded as an unfavorable independent prognostic factor. These results may pave a way for a novel approach to effective treatment of RCC.

The significance of thymidine phosphorylase/platelet-derived endothelial cell growth factor activity in renal cell carcinoma

BACKGROUND

Thymidine phosphorylase (TP) is identical to platelet-derived endothelial cell growth factor (PDECGF) and has angiogenic activity. Little is known about the significance of TP/PDECGF activity in patients with renal cell carcinoma (RCC). The authors examined the enzymatic activity of TP in 66 RCC specimens and investigated the association between the level of TP activity and the stage/grade status of patients with RCC. Furthermore, the authors examined the correlation between TP/PDECGF activity and prognosis.

METHODS

TP activity levels in nonfixed, fresh-frozen RCC specimens and in specimens of normal kidney were determined using a thin-layer chromatography assay.

RESULTS

The activity of TP was approximately 3.5-fold greater in RCC specimens compared with normal kidney specimens. TP activity in patients with Stage III-IV RCC was 2.6-fold greater compared with TP activity in patients with Stage I-II RCC. In addition, the level of TP activity was correlated with a higher grade of RCC. Patients who had RCC with low TP activity had a longer postoperative disease-specific survival compared with patients who had RCC with high TP activity in the 5-year follow-up.

CONCLUSIONS

The current study is the first to demonstrate a correlation between levels of TP activity and both disease progression and a higher grade of RCC. It also is the first to show that elevated TP activity in patients with RCC predicts a poor prognosis. The results suggest that high TP/PDECGF activity may be associated with the malignant potential of RCC and that TP/PDECGF may be a molecular therapeutic target in patients with RCC.