Startseite Kongressberichte & Archiv 45th Annual Meeting of the European Society for Blood and Marrow Transplantation (EBMT) Oral Session 9: Late-breaking abstracts OS9-4 - EFFECTIVE CANCER IMMUNOTHERAPY WITH ERBB2-CAR-ENGINEERED CYTOKINE-INDUCED KILLER (CIK) CELLS IN HIGH-RISK SOFT TISSUE SARCOMAS

Michael Merker1, Juliane Wagner1, Vida Meyer1, Evelyn Ullrich1, Thomas Klingebiel1, Winfried S. Wels2, Peter Bader1, Eva Rettinger1 1University Hospital Frankfurt, Department for Children and Adolescents, Frankfurt, Germany, 2Institute for Tumor Biology and Experimental Therapy, Georg-Speyer-Haus, Frankfurt, Germany

Background: Pediatric patients with high-risk alveolar rhabdomyosarcoma (aRMS) above the age of 10 years cannot be cured by conventional therapies. Immune cells targeting ErbB2 with a chimeric antigen receptor (CAR) were recently considered for these patients. Cytokine-induced killer (CIK) cells already capable of natural killer (NK)-like anti-tumor capacity additionally redirected with an ErbB2 CAR may provide overall disease control in these high-risk tumors.
Methods: ErbB2-CAR modified CIK cells were generated from conventional CIK cells (WT-CIK) by lentiviral gene transduction on day 4 of culture. The codon-optimized CAR sequence consists of an IgG heavy-chain signal peptide, an ErbB2-specific antibody fragment scFv (FRP5) and a modified CD8α hinge region, as well as CD28 transmembrane and intracellular domains and a CD3ζ intracellular domain. 1x105 luciferase gene-transduced RH30 (aRMS) cells were engrafted in immunodeficient NOD/SCID/γc-(NSG) mice. Mice were randomly selected into 5 different treatment groups (DBPS on day +1, 2.5x106 WT-CIK or ErbB2 CAR-CIK cells on days +1 and +36, 2.5x106 WT-CIK or ErbB2 CAR-CIK cells on days +22 and +57). Mice were monitored by bioluminescence imaging (BLI) until day +100. Tumor engraftment and immune cell homing at tumor sites were analyzed by FACS, chimerism and immunohistochemistry analyses.
Results: Human RMS xenografts were established in all mice treated with DBPS only. Control-mice showed a median survival of 62 days. Human RMS was identified in all analyzed organs, with the highest tumor burden seen in livers of DBPS-treated mice.
Mice injected with WT or ErbB2-CAR CIK cells on days +1 and +36 showed a significant improved (p < 0.014 and p < 0.01) disease-free survival, respectively. Furthermore, no signs of tumor engraftment were shown by BLI in ErbB2 CAR-CIK cell treated mice while some of the mice treated with WT-CIK cells developed positive tumor signals between weeks 7 and 10. In 4 out of 6 (64%) WT- and in all (8 of 8, 100%) CAR-CIK cells treated mice no residual tumor cells were identified by PCR-based analysis. In contrast, tumor cells were detectable in all mice with delayed anti-tumor treatment applied on day +22 and +57. However, tumor growth was lower in these groups. Correspondingly, BLI showed delayed tumor engraftment in mice with WT- and even more with CAR-CIK cell treatment given on day 22. Treatment on day 22 resulted in a significantly improved survival of ErbB2-CAR CIK cell treated mice (p < 0.01), while survival was not improved after WT-CIK cell infusion (p > 0.07). Within all treatment groups, immune cells were detected by chimerism and FACS analyses. FACS analyses showed a significant increase of NK-like T cells (p < 0.01 and < 0.05, WT- and ErbB2-CAR CIK cells). Additionally, a higher, but not significant, amount of effector memory and stem cell memory T cells were detected.
Conclusions: These pre-clinical in vivo results indicate that ErbB2- CAR redirection of CIK cells improves both homing and NK-like cytotoxicity of CIK cells in the presence of ErbB2-positive tumors, implying that this therapy may represent a step forward in the treatment of patients with resistant, relapsed and advanced RMS.
Disclosure: Michael Merker, Juliane Wagner, Vida Meyer, Thomas Klingebiel, Winfried S. Wels and Eva Rettinger have nothing to declare. Peter Bader declares the following potential conflicts of interest: Novartis (consultancy: included expert testimony, speaker bureau, Honoraria), Medac (Research Funding, Patents and Royalties), Riemser (Research Funding), Neovii (Research Funding), Amgen (Honoraria).