GlaxoSmithKline's MAGE-A3 cancer immunotherapeutic fails to hit goals of Phase III lung cancer trial

GlaxoSmithKline announced Thursday that a late-stage study of its experimental MAGE-A3 antigen-specific cancer immunotherapeutic (ASCI) in patients with non-small-cell lung cancer (NSCLC) failed to meet either its first or second co-primary endpoints. Vincent Brichard, head of immunotherapeutics at the company's vaccines unit, said "we are disappointed" in the results, but "remain committed to the effort to identify a sub-population of NSCLC patients who may benefit from this investigational treatment."

The MAGRIT trial randomised 2312 patients with Stage IB, II and IIIA completely resected NSCLC, whose tumours expressed the MAGE-A3 gene, to receive MAGE-A3 ASCI or placebo over a period of 27 months. GlaxoSmithKline noted that in the study, the cancer immunotherapeutic did not significantly extend disease-free survival (DFS) versus placebo in either the overall study population or among those who did not receive chemotherapy.

The drugmaker indicated it will continue the study in order to assess the third co-primary endpoint, which is DFS in a gene-signature-positive sub-population, with results expected in 2015. According to the company, MAGE-A3 is expressed in approximately one third of tumours in patients diagnosed with Stage IB-IIIA NSCLC. GlaxoSmithKline added that the trial's independent data monitoring committee concluded that its review of the current safety information raised no specific concern for the continuation of the study.

In September last year, the company reported that MAGE-A3 ASCI failed to meet its first co-primary endpoint of significantly extending DFS compared to placebo in a Phase III trial of patients with melanoma. GlaxoSmithKline is continuing the DERMA study to evaluate whether a gene signature can identify a subset of patients with melanoma that would benefit from the cancer immunotherapeutic, with results expected next year. MAGE-A3 ASCI contains Agenus' QS-21 Stimulon adjuvant.

Commenting on the latest results, Citigroup analyst Andrew Baum said expectations for MAGE-A3 ASCI were low because earlier studies showed a lack of T-cell response to the injection, a sign that the immune system may not be reacting. "We continue to estimate a 10-percent probability that GlaxoSmithKline's MAGE-A3 vaccine could result in a significant benefit in a gene-signature-defined population," he remarked, adding that sales of the product could reach 216 million pounds ($356 million) in 2022.

For related analysis, see ViewPoints: Cautious analysts proven correct as GlaxoSmithKline's cancer vaccine fails to deliver in NSCLC and In Focus: Can GlaxoSmithKline deliver on the promise of cancer vaccines?

To read more Top Story articles, click here.