FOLFOX plus panitumumab or FOLFOX alone as additive therapy following R0/1 resection of RAS wild-type colorectal cancer liver metastases: The PARLIM trial (AIO KRK 0314).

3553 Background: This trial investigates the addition of panitumumab to chemotherapy with fluorouracil/ folinic acid and oxaliplatin (FOLFOX) in a 2:1 randomized, controlled, open label, phase II trial in RAS wild-type colorectal cancer patients with R0/1-resected liver metastases. Methods: The primary endpoint was progression-free survival (PFS) two years after randomisation. The experimental arm (12 wks of biweekly mFOLFOX6 plus panitumumab followed by 12 wks of panitumumab alone) was considered active if the 2-year-PFS rate was ≥65%. Based on historical data, a 2-year-PFS rate of 50% was estimated in the control arm (12 wks of biweekly FOLFOX). The trial was performed with a power of 80% and an alpha of 0.05. Secondary endpoints included overall survival (OS) and toxicity. The trial is registered with ClinicalTrials.gov, NCT01384994. Results: The full analysis set consists of 70 patients (pts) in the experimental arm and 36 pts in the control arm. The 2-year-PFS rate was 34.3% with FOLFOX plus panitumumab and failed to meet the primary endpoint. The 2-year-PFS rate in the control arm was 25%. In the experimental arm, a more favourable outcome was observed with regard to PFS (HR: 0.72, 95%CI 0.45-1.17; P = 0.18) and OS (HR: 0.76 (95% CI 0.34-1.71, P = 0.51) which did, however, not reach the level of significance. Updated data including toxicity and subgroup analyses might be presented at the meeting Conclusions: The PARLIM trial clearly failed to demonstrate a PFS rate of 65% after resection of colorectal liver metastases 2 years after randomisation, potentially indicating that the generally high frequency of recurrence and the choice of primary endpoint did not correspond in this study population. However, a trend for improved PFS and OS by the addition of panitumumab to 12 wks of FOLFOX followed by 12 wks panitumumab maintenance therapy may support future trials with ant-EGFR antibodies in this specific treatment setting. Clinical trial information: NCT01384994.