GlaxoSmithKline's cancer drug candidate fails endpoint in melanoma

UK pharma giant GlaxoSmithKline (LSE: GSK) and partner US biotech firm Agenus (Nasdaq: AGEN) this morning (September 5) announced that the Phase III DERMA study of investigational MAGE-A3 antigen-specific cancer immunotherapeutic in melanoma did not meet the first co-primary endpoint of significantly extend disease-free survival when compared to placebo in the overall MAGE-A3 positive trial population. GSK’s shares drifted 1.7% lower to 1637.68 pence in mid-morning trading.

In line with the Independent 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 DERMA study evaluated the efficacy and safety of the MAGE-A3 cancer immunotherapeutic in Stage IIIB/C melanoma patients with macroscopic nodal disease, whose tumors expressed the MAGE-A3 gene and had their tumors removed surgically. MAGE-A3 is a tumor-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.