Abstract SY27-03: Biomarker-guided development of novel multi-peptide cancer vaccines - from discovery to phase lll trials.
2013-04-01

Abstract Translational research and the clinical development of therapeutic cancer vaccines require strong scientific rationale in order to better understand the mode-of-action and to incorporate the lessons learned in the optimization of cancer vaccines by (i) selecting appropriate immunomodulators to generate more effective vaccine regimens, (ii) combining vaccine regimens and standard-of-care therapeutics with synergistic potential and (iii) identifying patient populations that may have a better chance of responding to the vaccine. Here we demonstrate how preclinical and clinical immune response markers combined with cellular and serum biomarkers that define the immune regulatory environment were utilized as guiding tools in the development of three novel multi-peptide vaccines in renal cell cancer (IMA901), colorectal cancer (IMA910) and glioblastoma (IMA950). All three vaccine products comprise multiple tumor-associated peptides (TUMAPs) confirmed, by mass spectrometry, to be naturally presented in human cancer tissue. Each vaccine was selected using differential transcriptomics approaches and validated by in vitro analysis of immunogenicity with artificial antigen-presenting cells followed by in vivo analysis of immune responses in clinical trials. The vaccines contain HLA class I and II-restricted peptides designed to elicit CD8+ cytotoxic and CD4+ helper T-cell responses, respectively. IMA901 is a novel renal cell cancer (RCC) vaccine consisting of 9 HLA class I and 1 HLA class II TUMAPs with the majority of peptides confirmed to be naturally presented on and shared between RCC tissues. Consecutive independent Phase I and II clinical studies were conducted in HLA-A*02+ advanced/metastatic RCC patients (total 96) receiving repeated intradermal vaccinations with IMA901 plus human granulocyte-macrophage colony-stimulating factor (GM-CSF). The two studies demonstrated an association between overall survival and multiple vaccine-induced T-cell responses and an impact of single-dose cyclophosphamide (300 mg/m2) on regulatory T cells (Tregs) and overall survival. Furthermore, two myeloid-derived suppressor cell (MDSC) populations (CD14+ HLA-DR−/low and CD14− CD11b+ CD15+) were significantly negatively associated with survival in vaccinated RCC patients. The knowledge acquired in these trials was used to design a randomized, controlled Phase III study. Recruitment of 339 advanced/metastatic first-line RCC patients was recently completed. IMA901 is combined with the tyrosine kinase inhibitor sunitinib based on the findings that sunitinib down-modulates the two MDSC populations described above. Furthermore, in this Phase III study, the relevance of two serum biomarkers (Apoliprotein A1 and CCL17) found in the Phase II study to be associated with immune response and OS will be prospectively explored (Walter, Weinschenk et al., Nat Med 2012). IMA910 is a novel colorectal cancer (CRC) vaccine consisting of 10 HLA class I and 3 HLA class II TUMAPs with the majority of peptides confirmed to be naturally presented on and shared between CRC tissues. A Phase I/II trial was conducted in 92 HLA-A*02+ advanced colorectal cancer patients with stable (SD) or responding (PR/CR) disease after 12 weeks of first-line oxaliplatin-based therapy. Thereafter, first-line oxaliplatin-based chemotherapy was stopped and patients received a single dose of cyclophosphamide to reduce Tregs followed by repeated intradermal vaccinations with IMA910 plus GM-CSF (first cohort; n=66) with or without topically applied imiquimod (second cohort; n=26). IMA910 elicited immune responses towards multiple class I (in 43% of the subjects) and class II TUMAPs (65%). Similarly to the IMA901 vaccine trial in RCC, such vaccine-induced CD8+ as well as CD4+ T-cell responses to multiple TUMAPs were associated with increased overall survival. Patients who additionally received imiquimod were more often multi-peptide class I responders (p=0.016) as determined by intracellular cytokine staining (ICS) assay and showed a modestly (two-fold) increase of T-cell freqencies (p=0.12) as determined by HLA multimer assay. Interestingly, the same two populations of MDSC as described above in renal cell cancer patients were negatively associated with vaccine-induced immune response and overall survival implying a potential generalized role of these two MDSC populations. Further development of this vaccine is planned in a setting where an MDSC-modulating standard-of-care (e.g. chemotherapy) is applied. IMA950 is a novel glioblastoma vaccine consisting of 9 HLA class I and 2 HLA class II TUMAPs with the majority of peptides confirmed to be naturally presented on and shared between glioblastoma tissues. A Phase I study sponsored by Cancer Research UK is currently ongoing in the United Kingdom. A total of 45 newly diagnosed glioblastoma patients will be treated. The study is expected to complete recruitment in the first quarter of 2013. The primary objectives of this first-in-man study are to assess the safety, tolerability and immunogenicity of IMA950 plus GM-CSF when given alongside standard chemoradiotherapy followed by adjuvant chemotherapy with temozolomide. Patients enter the trial into one of two cohorts (start of vaccination either prior to or after initial chemoradiotherapy) in order to determine potential differences in the immune response in these two cohorts. First immunomonitoring data indicate a high immune as well as multi-TUMAP response rate in the study population. Updated and unpublished immune data will be presented at the meeting. Analysis of the in vitro immunogenicity data obtained from healthy donors during the discovery phases of these programs and comparison of these data with the in vivo immunogenicity data obtained in the clinical trials demonstrated that in all four clinical trials in a total of approx. 200 patients the in vitro data correlated with the in vivo data. This implies that such a standardized in vitro assay system may be utilized in future to further optimize vaccine regimens by selecting the most immunogenic novel peptides before entering clinical trials. In conclusion, we suggest that use of preclinically well characterized naturally presented tumor antigens combined with systematic clinical immunomonitoring and cellular/serum biomarker screening will be helpful to guide rational development of novel cancer vaccines. Citation Format: Harpreet Singh-Jasuja, Steffen Walter, Toni Weinschenk, Alexandra Kirner, Andrea Mayer-Mokler, Norbert Hilf, Oliver Schoor, Pierre-Yves Dietrich, James Richtie, Roy Rampling, Frank Mayer, Arnulf Stenzl, Brian Rini, Carsten Reinhardt, Hans-Georg Rammensee. Biomarker-guided development of novel multi-peptide cancer vaccines - from discovery to phase lll trials. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr SY27-03. doi:10.1158/1538-7445.AM2013-SY27-03