External validation of a sunitinib prognostic nomogram in patients (pts) with metastatic renal cell carcinoma (mRCC).
e15070 Background: A nomogram was previously developed from pretreatment clinical features to predict the probability of achieving 12-month progression-free survival (PFS) with sunitinib in treatment (Tx)-naïve mRCC pts from a randomized, phase 3 trial (Cancer 2008;113:1552). Here, validation and update of this nomogram using pts from a phase 2 sunitinib mRCC study (Renal EFFECT Trial) is reported, as is evaluation of its usefulness for clinical decision making. Methods: The Tx-naïve mRCC pts included in the current analysis were randomized 1:1 to sunitinib 50 mg/d on a 4-weeks-on-2-weeks-off schedule (Schedule 4/2; n=146) or 37.5 mg/d on a continuous daily dosing (CDD) schedule (n=146). The variables included in the prior nomogram and used here for validation purposes were corrected serum calcium, number of metastatic sites, hemoglobin, prior nephrectomy, presence of lung and liver metastases, ECOG performance status, thrombocytosis, time from diagnosis to treatment, alkaline phosphatase, and lactate dehydrogenase. The nomogram was updated by removing prior nephrectomy as a variable, including baseline neutrophils and presence of bone metastases, and replacing thrombocytosis with baseline platelets. Validation of the existing and updated nomograms consisted of quantification of the discrimination with the concordance index. A decision curve analysis was used to examine whether this prediction model is useful for medical decision making. Results: With comparable pt characteristics and no significant difference in PFS (8.5 vs. 7.0 months; P=0.070) between the Schedule 4/2 and CDD arms of the phase 2 trial, the combined pt population (N=292) was used to validate the existing nomogram. The overall concordance index was 0.615. Based on the decision curve analysis, the existing nomogram has clinical utility when the probability of 12-month PFS exceeds 60%. Using Schedule 4/2 pts only, the concordance index was 0.594 for the updated nomogram; however, its utility showed more variability. Conclusions: The sunitinib nomogram has been validated in a similar pt cohort; however, its clinical utility may be limited and more research is needed to refine the tool further.