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Data Support Vectibix With FOLFOX for Some Metastatic Colorectal Cancer Patients

Benefit shown in cases of wild-type RAS disease

New data from the phase 2 PEAK and phase 3 PRIME studies support the first-line use of Vectibix (panitumumab, Amgen) 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.

The data were part of a poster session at the 2015 American Society of Clinical Oncology Gastrointestinal Cancers Symposium in San Francisco from January 15 to 17.

In an exploratory analysis from the PEAK study, treatment with Vectibix compared to bevacizumab (Avastin, Genentech) resulted in a significantly higher proportion of patients with earlier tumor shrinkage at week 8 (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.

While the primary analysis from PEAK showed similar ORR between the Vectibix- and bevacizumab-based regimens, Amgen said this exploratory analysis demonstrates that Vectibix produces early, sustained antitumor 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 3 PRIME study 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.

The PEAK (Panitumumab Efficacy in Combination with mFOLFOX6 Against bevacizumab plus mFOLFOX6 in mCRC subjects with wild-type KRAS tumors) study is a global, multicenter, randomized, interventional phase 2 trial designed to compare efficacy of first-line Vectibix in combination with mFOLFOX6 versus bevacizumab in combination with mFOLFOX6 in 285 previously untreated patients with wild-type KRAS exon 2 metastatic colorectal cancer. Primary endpoints include PFS, and secondary endpoints include OS, ORR, duration of response, depth of response, and safety.

The PRIME (Panitumumab Randomized trial In combination with chemotherapy for Metastatic colorectal cancer to determine Efficacy) study is a global, multicenter, randomized phase 3 study designed to evaluate Vectibix in combination with FOLFOX versus FOLFOX alone in 1,183 patients with wild-type KRAS exon 2 metastatic colorectal cancer. Primary endpoints include PFS, and secondary endpoints include OS, ORR, duration of response, and safety.

In this analysis, quality of life (QoL) was assessed every four weeks until disease progression, and once at a safety follow-up, using the EuroQoL 5-domain health state index and overall health rating (OHR; 0–100 visual analogue scale).

Vectibix, a fully human anti-EGFR antibody, was approved in the U.S. in September 2006 as a monotherapy for the treatment of patients with EGFR-expressing metastatic colorectal cancer after disease progression after prior treatment with fluoropyrimidine-, oxaliplatin-, and irinotecan-containing chemotherapy. In May 2014, the FDA approved Vectibix for use in combination with FOLFOX as first-line treatment in patients with wild-type KRAS (exon 2) mCRC.

Source: Amgen; January 15, 2015.

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