Advances in so-called cancer vaccines were discussed at the ESMO Symposium on Immuno-oncology in Geneva. In the most elaborate study to date on this topic, researchers are currently investigating the efficacy and safety of an active vaccine tailored to individual patients.
(ag) GAPVAC is the name of the phase I trial that was predominantly discussed at the symposium. The ambitious project is financed by the EU. It is testing two different vaccines (APVAC-1 and -2) in patients with glioblastoma and after conventional surgery. So we’re talking about “therapeutic” vaccines that don’t prevent cancer, but fight it when it’s already there. Both contain personalized antigens and should therefore be highly effective for individual patients.
Two vaccines
In all participants of the study, we identify genes expressed in the tumor, peptides on the human leukocyte antigen (HLA) (i.e., peptides recognized by T cells), cancer-specific mutations, and the ability of the immune system to generate a response to specific antigens. From this information, the following vaccines are created and administered:
APVAC-1: The first vaccine consists of peptides that researchers already have “in stock,” so to speak, since they are among 72 identified therapeutic targets in glioblastoma (i.e., overexpressed in tumor tissue). Peptide cocktails are created depending on which peptides a patient expresses and whether he or she can generate an immune response to them: For example, if a patient expresses 20 of the 72 tumor-associated target molecules and five of them generate an immune response, exactly these five are administered by vaccination. In this respect, APVAC-1 is also individualized.
APVAC-2: Here, a de novo synthesis has to take place, since APVAC-2 is supposed to consist of mutant peptides that are exclusively expressed by the respective tumor. These peptides are not kept in stock, as they are different and specific for each patient.
Personalized medicines
GAPVAC is an exceptionally elaborate and complicated study that has never been done before. Such a large effort for each individual patient is remarkable. Ultimately, the trend is moving in the direction of giving every patient his or her own medicine. For the time being, however, it remains completely unclear how the healthcare system – even taking into account the reduced follow-up costs – is supposed to cope with such an approach.
Source: “Novel cancer antigens for personalised immunotherapies”, presentation at ESMO Symposium, November 21, 2014, Geneva.
InFo ONCOLOGY & HEMATOLOGY 2014; 2(10): 3.
