Strike 3 for MAGE-A3: GSK Cancer Vaccine Misses Third Endpoint
GlaxoSmithKline (GSK) said today it will halt its Phase III MAGRIT trial of its MAGE-A3 in non-small cell lung cancer (NSCLC) after acknowledging the experimental cancer vaccine missed its third co-primary endpoint—nearly two weeks after missing the first two, forcing the company to chalk up the drug as a late-stage failure.
GSK said it was stopping the trial “after establishing that it will not be possible to identify a subpopulation of gene-signature positive NSCLC patients that may benefit from the treatment.” That assessment came 13 days after the company reported that MAGE-A3 failed to meet the other two co-primary endpoints: MAGE-A3 did not significantly extend disease-free survival (DFS) when compared to placebo in either the overall MAGE-A3 positive population or in MAGE-A3-positive patients who did not receive chemotherapy.
According to GSK, a preplanned independent third-party analysis of a proportion of the data collected to identify a gene signature classifier concluded that the drug’s treatment effect was insufficient, thus assessment of the third co-primary endpoint was not feasible. However, the trial’s Independent Data Monitoring Committee (IDMC) saw no specific safety concern following its review of the current safety information revealed, and that the data it did see was in line with the known safety information for MAGE-A3.
“While we are extremely disappointed to learn that this trial did not have a positive outcome for the patients who participated in this trial, we are very grateful to its participants,” Vincent Brichard, svp and head of immunotherapeutics, GSK Vaccines, said in a statement. We hope that the data generated in this trial will advance our understanding of the science of immunotherapeutics, and ultimately toward development of new therapies.”
MAGRIT was intended to evaluate the efficacy and safety of MAGE-A3 in Stage IB, II and IIIA completely resected NSCLC patients whose tumors expressed the MAGE-A3 gene. MAGRIT enrolled 2,312 MAGE-A3-positive patients across more than 400 sites in 34 countries worldwide.
MAGE-A3 is a tumor-specific antigen expressed in a variety of cancers but not in normal cells.
GSK added that it was continuing another Phase III trial for MAGE-A3—DERMA, which is designed to evaluate whether a gene signature can identify a subpopulation of melanoma patients that would benefit from the same investigational MAGE-A3 cancer immunotherapeutic. DERMA followed GSK’s readout of data for the first co-primary endpoint in September 2013, namely DFS in the overall MAGE-A3-positive population.
Work is progressing on a mathematical model—the gene signature classifier—to allow assessment of DFS in the gene signature population, the second co-primary endpoint in DERMA, the company said. The trial’s outcome is expected to be available in 2015.