Frequency of expression and generation of T-cell responses against antigens on multiple myeloma cells in patients included in the GMMG-MM5 trial

// Michael Schmitt 1, * , Angela G. Huckelhoven 1, * , Michael Hundemer 1 , Anita Schmitt 1 , Susanne Lipp 1 , Martina Emde 1 , Hans Salwender 2 , Mathias Hanel 3 , Katja Weisel 4 , Uta Bertsch 1 , Jan Durig 5 , Anthony D. Ho 1 , Igor Wolfgang Blau 6 , Hartmut Goldschmidt 1, 7 , Anja Seckinger 1 and Dirk Hose 1 1 Universitatsklinikum Heidelberg, Medizinische Klinik V, Heidelberg, Germany 2 Department of Internal Medicine II, Asklepios Klinik Altona, Hamburg, Germany 3 Department of Internal Medicine III, Klinikum Chemnitz GmbH, Chemnitz, Germany 4 Department of Hematology, Oncology and Immunology, University of Tubingen, Tubingen, Germany 5 Department of Hematology, University Hospital Essen, Essen, Germany 6 Medical Clinic III Hematology and Oncology, Charite University Medicine Berlin, Berlin, Germany 7 Nationales Centrum fur Tumorerkrankungen, Heidelberg, Germany * These authors contributed equally to this work Correspondence to: Dirk Hose, email: dirk.hose@med.uni-heidelberg.de Keywords: tumor associated antigens, T cells, immunogenicity, multiple myeloma, RNA-sequencing Received: May 20, 2016      Accepted: July 13, 2016      Published: August 11, 2016 ABSTRACT Background: Raising T-cell response against antigens either expressed on normal and malignant plasma cells (e.g. HM1.24) or aberrantly on myeloma cells only (e.g. cancer testis antigens, CTA) by vaccination is a potential treatment approach for multiple myeloma. Results: Expression by GEP is found for HM1.24 in all, HMMR in 318/458 (69.4%), MAGE-A3 in 209/458 (45.6%), NY-ESO-1/2 in 40/458 (8.7%), and WT-1 in 4/458 (0.8%) of samples with the pattern being confirmed by RNA-sequencing. T-cell-activation is found in 9/26 (34.6%) of patient samples, i.e. against HM1.24 (4/24), RHAMM-R3 (3/26), RHAMM1-8 (2/14), WT-1 (1/11), NY-ESO-1/2 (1/9), and MAGE-A3 (2/8). In 7/19 T-cell activation responses, myeloma cells lack respective antigen-expression. Expression of MAGE-A3 , HMMR and NY-ESO-1/2 is associated with adverse survival. Experimental design: We assessed expression of HM1.24 and the CTAs MAGE-A3 , NY-ESO-1/2 , WT-1 and HMMR in CD138-purified myeloma cell samples of previously untreated myeloma patients in the GMMG-MM5 multicenter-trial by gene expression profiling (GEP; n = 458) and RNA-sequencing ( n = 152) as potential population regarding vaccination trials. We then validated the feasibility to generate T-cell responses ( n = 72) against these antigens by IFN-γ EliSpot-assay ( n = 26) related to antigen expression ( n = 22). Lastly, we assessed survival impact of antigen expression in an independent cohort of 247 patients treated by high-dose therapy and autologous stem cell transplantation. Conclusions: As T-cell responses can only be raised in a subfraction of patients despite antigen expression, and the number of responses increases with more antigens used, vaccination strategies should assess patients’ antigen expression and use a “cocktail” of peptide vaccines.