A meta-analysis of two randomized, double-blind, placebo-controlled, phase III studies in patients (pts) with metastatic colorectal cancer (mCRC) receiving FOLFOX4 and PTK/ZK to determine clinical benefit on progression-free survival (PFS) in high LDH pts
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abstract
3529 Background: PTK/ZK is an oral, antiangiogenic inhibitor of tyrosine kinase signaling of all known vascular endothelial growth factor receptors (VEGFR). PTK/ZK in combination with FOLFOX4 has been investigated in first line (CONFIRM 1[C1]) and second line (CONFIRM 2 [C2]) mCRC pts. Methods: In both trials, pts were randomized to receive PTK/ZK or placebo. Since high LDH and poor performance status (PS) have been shown to indicate poor prognosis in mCRC, pts were stratified by baseline serum LDH (≤ or > 1.5 X ULN) and PS (0, 1–2), yielding 4 strata per trial. Exploratory analysis of the high LDH strata in C1 indicated that these pts may derive the most benefit from PTK/ZK treatment. The purpose of this pre-planned meta-analysis of C1 and C2 is to determine whether the treatment effect of C1 and C2 are consistent. Results: Both trials showed strikingly similar results. High LDH pts comprise approximately 30% of the total pt population. PTK/ZK seems to have the same strong effect on PFS in high LDH pts in both 1st and 2nd line mCRC with a HR for PFS of 0.67 (p =0.010) for C1 and 0.63 (p < 0.001) for C2 (N=250 and N=316, respectively). The safety profile of PTK/ZK was highly consistent. The most frequent grade 3/4 AEs attributable to PTK/ZK were hypertension, diarrhea, fatigue, nausea, vomiting and dizziness. Increases in AEs associated with antiangiogenic therapy such as bowel perforations and bleeding complications were not observed in the PTK/ZK arms of both trials. In the meta-analysis, PTK/ZK effect on PFS is moderate in the overall population (HR 0.85, p-value 0.005). In contrast, the effect on PFS is strong and clinically meaningful in the high LDH population (HR 0.65, p-value < 0.001, N=566). Conclusion: This meta-analysis is the largest study of poor prognosis pts with high serum LDH in metastatic colorectal cancer. These data suggest that PTK/ZK significantly improves PFS in high LDH pts. Further evaluation of PTK/ZK in this pt population is planned. [Table: see text]
