Amgen has 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 was 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 Vectibix compared to bevacizumab (Avastin) resulted in a significantly higher proportion of patients with earlier tumour shrinkage at week eight (64% vs. 45%, respectively; 95% CI, p=0.0232), and among responding patients, a significantly longer duration of response (11.4 vs. 8.5 months, respectively; 95% CI, p=0.0142) and greater depth of response (65% vs. 46%, respectively; p=0.0007). Overall response rates (ORR) appeared to be similar between Vectibix 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 Vectibix was consistent with previously reported studies.
"These analyses help deepen our understanding of how Vectibix works when added to a standard first-line chemotherapy for the treatment of wild-type RAS metastatic colorectal cancer," said Sean E. Harper, executive vice president of R&D at Amgen. "Our Vectibix clinical trial program continues to yield new insights regarding biomarkers and drug sequencing."
While the primary analysis from PEAK showed similar ORR between the Vectibix- and bevacizumab-based regimens, this exploratory analysis demonstrates that Vectibix produces early, sustained anti-tumor activity, which may in part explain the OS and PFS benefits seen with Vectibix 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 Vectibix 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.
