FOLFIRI and sunitinib as first-line treatment in metastatic colorectal cancer patients with liver metastases - a CESAR phase II study including pharmacokinetic, biomarker, and imaging data

Background: The aim of this study was the evaluation of pharmacokinetic parameters, biomarkers, clinical outcome, and imaging parameters in metastatic colorectal cancer (mCRC) patients treated with FOLFIRI plus sunitinib. Methods: mCRC patients with liver metastases were treated with FOLFIRI and sunitinib as 1st line therapy. At protocol-defined time points, multi-contrast magnetic resonance imaging (MRI) measurements, computed tomography (CT) scans, pharmacokinetics (PK), and biomarker analyses were performed during the first and second treatment cycle. Thereafter, patients were treated until tumor progression, investigator's decision due to toxicity, or patient withdrawal. Results: 28 patients were screened, 26 were included, and 23 received at least one study medication. Full safety analysis was performed in 23 patients. Full PK and biomarker analyses were performed in 21 patients. Strong responses in tumor size reduction forced a change from the original imaging timing scheme. This unforeseen change in the timing scheme resulted in subgroups too small for meaningful statistical analysis of most imaging parameters. Thus, only a descriptive analysis of the MRI data was possible. In 21/22 patients, MRI showed a decrease of the liver metastases. Best response was partial remission (PR) in 8/17 patients. Plasma concentrations of sVEGFR-2 and sVEGFR-3 decreased in all patients. The majority of the patients developed some kind of toxicity not always deducible to FOLFIRI or sunitinib. Conclusions: Due to the observed side effect profile, FOLFIRI plus sunitinib 37.5 mg per day cannot be recommended for previously untreated mCRC.