GlaxoSmithKline (GSK) today reported the second Phase III failure in six months for its cancer vaccine candidate MAGE-A3, saying it did not meet its first or second co-primary endpoint in the MAGRIT trial assessing the therapeutic in non- small cell lung cancer (NSCLC).

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, GSK said.

“We are disappointed that the trial did not demonstrate a benefit for overall MAGE-A3 positive patient population, but we remain committed to the effort to identify a sub-population of NSCLC patients who may benefit from this investigational treatment,” Vincent Brichard, svp and head of immunotherapeutics for GSK Vaccines, said in a statement.

GSK did not detail MAGRIT data, saying it remained blinded “to allow for unbiased generation of a mathematical model to assess the third co-primary endpoint.”

The company said MAGRIT will continue in order to allow assessment of that co-primary endpoint, identification of a subset of MAGE-A3 positive patients that may benefit from the treatment with the cancer vaccine. Results from a final analysis of that endpoint are expected in 2015.

GSK cited a finding from the trial’s Independent Data Monitoring Committee (IDMC), whose review of safety information raised no specific concern for the continuation of the trial and was “in line with the known safety information for the MAGE-A3 cancer immunotherapeutic.”

MAGRIT was designed to evaluate the efficacy and safety of the MAGE-A3 cancer immunotherapeutic in Stage IB, II and IIIA completely resected NSCLC patients whose tumors expressed the MAGE-A3 gene. Patients were given up to 13 intramuscular injections of either the immunotherapeutic or placebo over 27 months.

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.

In September, MAGE-A3 failed its first co-primary endpoint in the Phase III DERMAi trial of 1,345 melanoma patients by showing no statistically significant extension of disease-free survival compared with placebo in the overall MAGE-A3 positive population.

GSK has continued DERMA, evaluating whether a gene signature can identify a subpopulation of melanoma patients that would benefit from the cancer immunotherapeutic. According to the company, work is progressing on a mathematical model intended to allow assessment of DFS in the gene signature population, the second co-primary endpoint in the study. The outcome is expected in 2015.

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