Analysis of PEAK and PRIME trials comparison of Vectibix and Avastin in Colorectal Cancer-Amgen

Amgen announced new data from the Phase II PEAK and Phase III PRIME studies that support the first-line use of Vectibix (panitumumab) in combination with FOLFOX, an oxaliplatin-based chemotherapy regimen, in patients with wild-type RAS (absence of exons 2, 3, or 4 KRAS or NRAS mutations) metastatic Colorectal Cancer (mCRC). The data were presented during a poster session at the 2015 American Society of Clinical Oncology (ASCO) Gastrointestinal Cancers Symposium taking place in San Francisco from 15–17 January.

In an exploratory analysis from the PEAK study (abstract #660), treatment with panitumumab compared to bevacizumab resulted in a significantly higher proportion of patients with earlier tumor shrinkage at week eight (64% vs. 45%, respectively; p=0.0232), and among responding patients, a significantly longer duration of response (11.4 vs. 8.5 months, respectively; p=0.0142) and greater depth of response (65% vs. 46%, respectively; p=0.0007). Overall response rates (ORR) appeared to be similar between panitumumab and bevacizumab. This is consistent with observed overall survival (OS) and progression-free survival (PFS) rates, and with data previously reported. The safety profile of panitumumab was consistent with previously reported studies. While the primary analysis from PEAK showed similar ORR between the panitumumab- and bevacizumab-based regimens, this exploratory analysis demonstrates that panitumumab produces early, sustained anti-tumor activity, which may in part explain the OS and PFS benefits seen with panitumumab versus bevacizumab in this trial.

A separate analysis from the Phase III PRIME study (abstract #537), demonstrated that there were no significant differences in quality of life among patients treated with panitumumab plus FOLFOX versus FOLFOX alone despite the incidence of adverse events associated with each treatment regimen. The quality of life analysis included a scale that assessed mobility, self-care, usual activities, pain/discomfort and anxiety/depression.