Merck Serono, a division of Merck KGaA, Darmstadt, Germany, announced the initiation of its global phase-III clinical study of the therapeutic cancer vaccine Stimuvax (BLP25 liposome vaccine, L-BLP25) in patients with advanced, inoperable breast cancer. The STRIDEa study will determine if Stimuvax can extend progression-free survival in patients treated with hormonal therapy who have hormone receptor-positive, locally advanced, recurrent or metastatic breast cancer. Overall survival, quality of life, tumour response and safety will also be assessed in this study. The Stride study will be supervised by an expert Steering Committee and is sponsored by Merck Serono, which is leading the development of Stimuvax.

Stride will enrol more than 900 patients with advanced breast cancer at an estimated 180 sites in over 30 countries - within North America, Europe, Asia and Australia; the principal investigator is Dr Lawrence Shulman, chief medical officer and senior vice president for Medical Affairs, Dana-Farber Cancer Institute, Boston, USA.

"Advanced-stage breast cancer remains an ultimately fatal and challenging disease and we urgently need new treatment options," said Dr Shulman. "If the results from the phase-III Stride study prove positive, this could make a difference for patients with hormone receptor-positive metastatic breast cancer."

Stimuvax is an investigational therapeutic cancer vaccine designed to stimulate the body's immune system to identify and target cancer cells that express MUC1, an antigen commonly expressed in breast cancer as well as in other common cancer types such as non-small cell lung cancer (NSCLC), multiple myeloma, and colorectal, prostate and ovarian cancers.

"The initiation of the Stride study is an enormous step forward in clinical breast cancer research and represents our continued commitment to developing Stimuvax within a robust clinical trial programme across several cancer types. We are very excited that Stimuvax will now be tested in two different cancer types in phase-III," said Dr Oliver Kisker, senior vice-president, Global Clinical Development Unit Oncology, Merck Serono.

The phase-III programme for Stimuvax was initiated following results from a randomized phase-IIb study of 171 patients with inoperable stage IIIb NSCLC, in which Stimuvax showed a trend towards extending median overall survival from 13.3 months for patients receiving best supportive care (BSC) to 30.6 months for patients receiving Stimuvax plus BSC.2,3 Reported side effects included mild-to-moderate flu-like symptoms, gastrointestinal disturbances and mild injection-site reactions. A further long-term safety analysis in 16 patients receiving prolonged treatment with Stimuvax from 2.0 to 8.2 years showed the most common treatment-related adverse events were injection-site reactions (ISRs) with no evidence of autoimmune reactions. These data also show that the occurrence of ISRs decreased with long-term therapy (>1 year).

Stimuvax was the first investigational cancer vaccine to enter phase-III clinical testing in NSCLC with the February 2007 launch of the START study, which will involve more than 1,300 patients with unresectable stage III NSCLC, who were stable or responding after chemoradiotherapy.

Merck is investigating the use of Stimuvax (BLP25 Liposome Vaccine) in the treatment of NSCLC. The vaccine was granted fast-track status in September 2004 by the FDA.