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Responses in renal cell cancer patients in phase I clinical trials: Drug activity or spontaneous remissions? A systematic review.

6061 Background: Renal cell cancer shows a particular behavior. These tumors show great heterogeneity, from aggressive forms to indolent ones. Less than 1% can experience a spontaneous regression and it has been described that about 6% of cases may respond to placebo. It is quite frequent to include these patients in phase I chemotherapy trials, where responses are found in approximately 4% of cases and these responses are not predictive to efficacy in further phase III.


METHODS
58 novel targeted drug phase I clinical trials were systematically reviewed, between 2001-2003 publications and ASCO abstracts, 20 of them testing antiangiogenic drugs, in order to know the preliminary activity of these compounds in renal cell cancer, in terms of response rate. Combinations with well-known active drugs were excluded.


RESULTS
We found 134 cases of renal cell cancer. There were 7 partial responses (5.0%); three of them in a study with SU11248 (TKI anti VEGF, PDGF, FT-1), testing the drug in 4 renal cancer cases. Excluding this study, only 4 partial responses were seen in 130 patients (3.0%). These responses were seen in one patient (pt) treated with the farnesyl transferasa inhibitor R115777, one with PTK787 (TKI anti VEGF, PDGF, FT-1), 1 pt TKI anti EGFR, OSI-774 and 1 pt BAY 43-9006 (anti Raf kinase). Considering only antiangiogenic studies, one response was seen in 20 studies which included 66 renal cancer patients (2%); 6.0% if we consider SU11248.


CONCLUSION
Renal cell cancers present sporadic responses in several new drugs phase I clinical trials, with an exception, SU11248. No other drug shows the same degree of interesting activity. Responses seen with other drugs excluding SU11248 could not be attributed to drug activity. No significant financial relationships to disclose.