Booster vaccination of non-small cell lung cancer (NSCLC) patients with MAGEA3 protein and AS02B adjuvant

Abstract

3015 Background: We have previously reported results of a phase II trial of recombinant ProtD/MAGE-3/His (MAGEA3) protein 300μg administered IM every three weeks for 4 doses with or without adjuvant AS02B to NSCLC patients following resection of MAGEA3 positive disease (JI, 172:3289, 2004). We found that the presence of adjuvant was essential for the development of strong humoral and cellular responses against selected MAGEA3 epitopes. Methods: 14 of the original 18 patients received booster vaccinations. Patients who still had no evidence of disease for up to two years after receiving their original MAGEA3 protein regimen (7 in cohort 1 without adjuvant, 7 in cohort 2 with adjuvant), received 4 additional doses of MAGEA3 protein with adjuvant. T cell immunomonitoring was extended to encompass any MAGEA3 epitope using full length antigen, and the scope of analysis of humoral responses was widened. Results: After just one boost injection, 6 of the 7 patients originally vaccinated with MAGEA3 protein plus adjuvant reached the peak of antibody titers to MAGEA3 attained during the first vaccination and went on to develop a stronger response than during the first cycle. In addition, the spectrum of CD4+ and CD8+ T cells against various new and known epitopes widened with booster vaccination. In contrast, only 3/7 patients originally vaccinated with MAGEA3 protein alone seroconverted to low-titered MAGEA3 responses and showed very limited CD4+ and no CD8+ T cell reactivity, despite now receiving antigen in the presence of adjuvant. Conclusions: These results underscore the importance of proper antigen priming using an adjuvant for generating persistent B and T cell memory, allowing for typical booster responses with re-immunization. In contrast, absence of adjuvant at priming may compromise further immunization attempts. These data provide immunological rationale for vaccine design in light of recently reported favorable clinical findings in NSCLC patients following vaccination with MAGEA3 protein plus adjuvant AS02B (GSK, ASCO 2005). No significant financial relationships to disclose.