The investigational MAGE-A3 antigen-specific cancer immunotherapeutic does not meet first co-primary endpoint in Phase III melanoma clinical trial

GlaxoSmithKline plc (LSE:GSK) today announced that an independent analysis of the DERMAi study, a Phase III randomised, blinded, placebo-controlled trial of the MAGE-A3 cancer immunotherapeutic,ii showed that the study did not meet its first co-primary endpoint as it did not significantly extend disease-free survival (DFSiii) when compared to placebo in the MAGE-A3 positive population.

The DERMA study evaluated the efficacy and safety of the MAGE-A3 cancer immunotherapeutic in Stage IIIB/C melanoma patients with macroscopic nodal disease, whose tumours expressed the MAGE-A3 gene and had their tumours removed surgically. MAGE-A3 is a tumour-specific antigen that is expressed in a variety of cancers, including melanoma with no presentation in normal cells. MAGE-A3 is expressed in about 65% of Stage III melanomas.

In line with the Inependent Data Monitoring Committee’s (IDMC) unanimous recommendation, GSK will continue the DERMA trial until the second co-primary endpoint is assessed. This endpoint, DFS in the gene signature positive sub-population, is designed to identify a subset of MAGE-A3 positive patients that may benefit from the treatment. Results from this analysis are expected in 2015. Until then, GSK will remain blinded to all safety and efficacy data.

The IDMC for the DERMA study indicated that the current review of the safety information raised no concern for the continuation of the trial.

“We want to thank all patients, their families and healthcare workers for their involvement in the trial and we remain committed to identifying a patient sub-population who may benefit from this investigational treatment,” commented Vincent Brichard, Senior Vice-President & Head of Immunotherapeutics, GSK Vaccines.

GSK is continuing to evaluate the same investigational MAGE-A3 cancer immunotherapeutic in another independent Phase III study (MAGRIT) in Non Small Cell Lung Cancer (NSCLC) following surgical removal of the primary tumour with first data anticipated in the first half of 2014.

References

i A double-blind, randomized, placebo-controlled Phase III study to assess the efficacy of recMAGE-A3 + AS15 antigen-specific cancer immunotherapeutic as adjuvant therapy in patients with MAGE-A3 positive resected stage III melanoma.(DERMA)

ii MAGE-A3 cancer immunotherapeutic consists of recombinant MAGE-A3 protein and a novel immunostimulant AS15 (a combination of QS-21 Stimulon® adjuvant, monophosphoryl lipid A, and CpG7909, a TLR-9 agonist, in a liposomal formulation). QS-21 Stimulon® adjuvant is licensed from Antigenics Inc, a wholly owned subsidiary of Agenus Inc. (NASDAQ: AGEN).

iii DFS is defined as the time from randomization to the date of first recurrence of the disease or death, whichever comes first.

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