Amgen's Vectibix® did not meet the primary endpoint in a Phase III trial evaluating its use as a first-line treatment for recurrent and/or metastatic squamous cell head and neck cancer. The data showed that the addition of Vectibix to platinum-based chemotherapy did not result in a statistically significant improvement in overall survival (OS) compared to chemotherapy alone. The median OS for the Vectibix group was 11.1 months versus 9.0 months for those receiving only chemotherapy.
Secondary endpoints of progression-free survival (PFS) and objective response rate (ORR) were numerically improved but were not tested for statistical significance, the firm reports. Median PFS was 5.8 months versus 4.6 months and ORR was 36% versus 25% for the Vectibix and chemo groups, respectively.
Vectibix is a human anti-EGFR antibody indicated as a monotherapy for metastatic colorectal cancer (mCRC). It was approved in the U.S. in September 2006 for the treatment of patients with EGFR-expressing mCRC after disease progression on or following fluoropyrimidine-, oxaliplatin-, and irinotecan-containing chemotherapy regimens.
In December 2007, the European Commission granted a conditional marketing authorization for Vectibix as a monotherapy for patients with EGFR-expressing mCRC with wild-type KRAS genes after failure of standard chemotherapy regimens. In total Vectibix has been launched in over 20 countries, and applications in the rest of the world are pending, says Amgen.
In 2009, Vectibix posted $233 million in sales versus $153 million in 2008, a 52% increase. In the first two quarters of this year the drug pulled in $139 million compared to $109 million for the same period in 2009. Sales growth was driven by international demand partially as a result of recent launches, Amgen notes.
The study in head and neck cancer, called SPECTRUM, enrolled 658 patients who were randomized to receive a standard platinum-based chemotherapy (cisplatin and 5-FU) with or without Vectibix (9 mg/kg) every three weeks. Besides PFS and ORR other secondary endpoints included duration of response, time to progression, time to response, patient reported outcomes, and safety. The most frequently reported adverse events in the Vectibix plus chemotherapy arm included nausea, rash, neutropenia, and vomiting, which is what Amgen expected.