I've been trying to follow news on this vaccine because I'm in the trial for it. It seems like good news for the vaccine may be forthcoming soon. So let's keep our fingers crossed that the Phase III trial data is as pivotal as they hope it will be. If it is, it'll be great for those with Stage III resectable melanoma who are MAGE-A3 positive. If I remember correclty from the literature I got at the beginning of the trial, about 65% of melanomas test positive for MAGE-A3.
GlaxoSmithKline: MAGE-A3 (Phase III/NSCLC & Melanoma)
Success Could Open Up a New Platform; 40% Probability of Success with Global Sales Estimate of £1.2B in 2018
GlaxoSmithKline (GSK) could be a beneficiary in an emerging area which utilizes the understanding of cancer as an immune disease. GSK’s candidate is MAGE - A3, an antigen-specific cancer immunotherapy (ASCI), which has shown interesting phase II data. Pivotal phase III data in NSCLC and melanoma are expected in 2013. We see 5%-10% GSK NPV upside on positive data, and minimal downside on negative data given consensus expectations.
We expect pivotal phase III data for MAGE-A3 in mid-2013. This applies to MAGRIT (NSCLC) and DERMA (melanoma) studies, which are both event-driven. As the MAGE-A3 antigen is not expressed in normal cells in the body, the MAGE-A3 ASCI only targets cancer cells. The MAGE-A3 ASCI is highly specific for its antigen, and as a result the product has low potential to harm noncancerous tissues that lack the antigen. The minimal side-effects and good tolerability seen in the clinical trial program of MAGE-A3 (and other cancer immunotherapies) are particularly encouraging when compared to chemotherapy which often has toxic, poison-like side-effects (nausea, vomiting, hair loss, bone marrow depletion, etc.). MAGE-A3 therefore has potential not just as a product but also as a platform, as proving utility in adjuvant NSCLC or melanoma might open the road for GSK to treating perhaps dozens of cancer types with vaccines.
While we acknowledge that cancer vaccines are currently a high-risk area of development, reflected in our 40% modeled probability of success and £1.2bn 2018 global sales estimate, we see several reasons for optimism in the product: (1) phase II studies showed strong trends to MAGE-A3 improvements on survival (DFS, OS); (2) all MAGE-A3 trials so far show impressive safety; (3) phase III studies have much more power to show statistical benefits than the phase II studies; (4) GSK has used gene profiling information to potentially identify responders; and (5) GSK has used more powerful adjuvants (immune boosters) which produce higher-quality results in its phase III trials.
For now, the potential and the risks are high for MAGE-A3 (and the business division that could emerge at GSK if the product works). Consensus does not model MAGE-A3 generally, so we see little scope for downside.