GlaxoSmithKline announced that interim results from a clinical trial in patients treated with GSK's investigational MAGE-A3 Antigen Specific Cancer Immunotherapeutic (ASCI) in Non-Small Cell Lung Cancer (NSCLC) resulted in a one third reduction in relative risk of cancer recurrence following surgery, compared to placebo.

MAGE-A3 ASCI is an investigational drug and it is not approved for use in any indication in any country at this time.

Formerly known as pharmaccines or therapeutic cancer vaccines, GSK's ASCIs aim at stimulating the patient's own immune response to attack cancer cells in a highly specific manner. This class of novel compounds is based on specific tumour antigens delivered as recombinant proteins in combination with innovative proprietary adjuvant systems specifically designed to ensure ASCIs induce a strong anti-tumour activity.

In this proof-of-concept Phase II clinical trial, all the participating patients had tumours expressing a tumour-specific antigen known as MAGE-A3, which is present in approximately 35 per cent to 50 per cent of early NSCLC.1 Although the observed 33 per cent reduction in relative risk of cancer recurrence did not meet statistical significance at this interim stage (p=0.121), the trend is very encouraging and warrants continued investigation.

These promising results from an interim analysis presented at the 2006 American Society of Clinical Oncology (ASCO) annual meeting in Atlanta, GA, represent the first proof-of-concept for activity for an ASCI approach in a double-blind, placebo-controlled clinical trial in early NSCLC.

The most commonly reported adverse events were mild local or systemic reactions observed within the 24 hours of injection. Out of 182 patients, 2 patients were withdrawn from the clinical trial due to adverse events possibly related to the MAGE-A3 treatment.

"This trial demonstrates the feasibility of developing novel cancer immunotherapies that with continuing research may expand into a new approach to cancer treatment" said Paul A. Bunn Jr., M.D., Grohne/Stapp Endowed Professor of Oncology, Professor of Medicine and Director of the University of Colorado Cancer Center, Denver, Colorado. "It represents an important step not only in finding better therapy for the most common type of lung cancer but also in exploring the broader potential of these compounds."

The study is a multi-center, randomized, double-blind, placebo-controlled Phase II trial evaluating MAGE-A3 ASCI as adjuvant therapy in patients with completely resected MAGE-A3 positive, stage IB or II NSCLC. The study randomized 182 patients to receive either MAGE-A3 ASCI or placebo.

This pre-planned interim analysis was performed at a median follow-up of 21 months. At this time, 37 of the 122 patients receiving MAGE-A3 ASCI had relapsed (30.3%); compared to 25 of the 60 patients receiving placebo (41.7%). Using a Cox regression model to adjust for the fact that patients in the different arms were enrolled in the study at different times, there was a 33 percent relative reduction in risk of cancer recurrence in patients treated with MAGE-A3 ASCI compared to placebo.2

"These first results obtained with our MAGE-A3 ASCI reinforce our belief in the potential application of the ASCI approach in the treatment of cancer", said Jean Stéphenne, President of GSK Biologicals. "Today's results demonstrate GSK's commitment to becoming a leader in this exciting new field of medicine based on our unique expertise in recombinant protein and adjuvant technology. In addition to MAGE-A3, GSK is building a broad portfolio of tumour antigens and by using the same approach, we are confident in our ability to develop a rich pipeline of ASCIs targeting in a highly specific manner many different types of cancers".

Vincent Brichard, Director Clinical Development Cancer Program at GSK Biologicals commented: "We are very encouraged by these results as they validate years of research conducted by GSK Biologicals and others into the ways to harness the immune system against cancer."

The full analysis will focus on time to recurrence, disease-free survival, overall survival, lung-cancer-related death rate as well as safety and immunogenicity. Final results are expected to be available later this year. Phase III trials are planned to begin in early 2007.