Phase II clinical and pharmacokinetic study of aflibercept in patients with previously treated metastatic colorectal cancer.

PURPOSE

Aflibercept is a recombinant fusion protein of the VEGF receptor (VEGFR) 1 and VEGFR2 extracellular domains. We assessed the safety and efficacy of aflibercept in patients with metastatic colorectal cancer (MCRC) who had received at least one prior palliative regimen.

EXPERIMENTAL DESIGN

Seventy-five patients were enrolled onto this two-stage phase II trial in two cohorts, bevacizumab naïve (n = 24) and prior bevacizumab (n = 51). Aflibercept was administered at 4 mg/kg i.v. in two-week cycles. The primary endpoint was a combination of objective response rate and 16-week progression-free survival (PFS).

RESULTS

In the bevacizumab-naïve cohort (n = 24), the best response was stable disease for 16 weeks or more in five of 24 patients. In the prior bevacizumab cohort (n = 50), one patient achieved a partial response and six patients had stable disease for 16 weeks or more. The median PFS in the bevacizumab-naïve and prior bevacizumab cohorts was two months [95% confidence interval (CI): 1.7-8.6 months] and 2.4 months (95% CI: 1.9-3.7 months), respectively. Median overall survival (OS) was 10.4 months (95% CI: 7.6-15.5) and 8.5 months (95% CI: 6.2-10.6), respectively. The most common grade 3 or higher treatment-related adverse events were hypertension, proteinuria, fatigue, and headache. Ten patients discontinued study treatment due to toxicity. Mean free to VEGF-bound aflibercept ratio was 1.82, suggesting that free aflibercept was present in sufficient amount to bind endogenous VEGF.

CONCLUSION

Aflibercept showed limited single-agent activity in patients with pretreated MCRC with moderate toxicity. Further study of aflibercept with chemotherapy is ongoing.