Merck announced that phase III clinical trials of its gastric cancer drug Erbitux fails to meet primary endpoints.

Phase III clinical trial EXPAND, which assessed Erbitux (cetuximab) in combination with cisplatin and capecitabine as a first-line treatment for patients with advanced gastric adenocarcinoma including adenocarcinoma of the gastro-esophageal junction (GEJ). The trial did not meet its primary endpoint of extending the length of time that patients live without their disease getting worse (progression-free survival - PFS), as determined by independent review.

“We are disappointed that the EXPAND trial did not show a benefit for patients with advanced gastric cancer when Erbitux was added to standard chemotherapy. Patients with advanced gastric cancer currently have few treatment choices and a poor prognosis, and we will continue to investigate other treatment options for these patients in the hope of being able to offer improved outcomes,” said lead investigator Professor Florian Lordick, MD, Klinikum Braunschweig, Hannover Medical School, Germany.

EXPAND was a multi-centre, open-label, randomized, controlled trial in 904 patients at 150 centres in 25 countries across Latin America, Europe, Asia Pacific and Japan. Patients had unresectable advanced cancer of the stomach or GEJ and had received no prior treatment with chemotherapy or radiotherapy in this setting. Usually, these patients would receive palliative chemotherapy only.

The study’s primary endpoint was PFS as determined by an independent review committee (IRC). Secondary endpoints were overall survival (OS), best overall response rate determined by IRC, safety and quality of life.

“Understandably, these results are disappointing for patients with advanced gastric cancer, and as a company we will continue to invest in oncology research and development to find new treatments for these diseases with high unmet medical need,” said Dr. Annalisa Jenkins, head of global drug development and medical for the Merck Serono division.

Erbitux is a first-in-class IgG1 monoclonal antibody targeting the epidermal growth factor receptor (EGFR). As a monoclonal antibody, the mode of action of Erbitux is distinct from standard non-selective chemotherapy treatments in that it specifically targets and binds to the EGFR. This binding inhibits the activation of the receptor and the subsequent signal-transduction pathway, which results in reducing both the invasion of normal tissues by tumour cells and the spread of tumours to new sites. It is also believed to inhibit the ability of tumour cells to repair the damage caused by chemotherapy and radiotherapy and to inhibit the formation of new blood vessels inside tumours, which appears to lead to an overall suppression of tumour growth.

The most commonly reported side effect with Erbitux is an acne-like skin rash that seems to be correlated with a good response to therapy. In approximately 5% of patients, hypersensitivity reactions may occur during treatment with Erbitux; about half of these reactions are severe.

Erbitux has already obtained marketing authorization in 92 countries. It has been approved for the treatment of colorectal cancer in 92 countries and for the treatment of squamous cell carcinoma of the head and neck (SCCHN) in 89 countries.

Merck licensed the right to market Erbitux outside the US and Canada from ImClone LLC, a wholly-owned subsidiary of Eli Lilly and Company, in 1998. In Japan, ImClone, Bristol-Myers Squibb Company and Merck jointly develop and commercialize Erbitux. Merck has an ongoing commitment to the advancement of oncology treatment and is currently investigating novel therapies in highly targeted areas.