title: Targeted cancer immunotherapy via combination of designer bispecific antibody and novel gene-engineered T cells.
abstract: BACKGROUND
  Redirection of T lymphocytes against tumor antigens can induce dramatic regression of advanced stage malignancy. The use of bispecific antibodies (BsAbs) that bind both the T-cell receptor (TCR) and a target antigen is one promising approach to T-cell redirection. However, BsAbs indiscriminately bind all CD3+ T-cells and trigger TCR activation in the absence of parallel costimulatory signals required to overcome T-cell unresponsiveness or anergy.
  
  
  METHODS
  To address these limitations, a combination platform was designed wherein a unique BsAb referred to as frBsAb exclusively engages T-cells engineered to express a novel chimeric receptor comprised of extracellular folate receptor fused to intracellular TCR and CD28 costimulatory signaling domains in tandem; a BsAb-binding immune receptor (BsAb-IR). As a surrogate TCR, the BsAb-IR allows for concomitant TCR and costimulatory signaling exclusively in transduced T-cells upon engagement with specific frBsAbs, and can therefore redirect T-cells on command to desired antigen. Human primary T-cells were transduced with lentiviral vector and expanded for 14-18 days. BsAb-IRs were harvested and armed with frBsAbs to test for redirected cytotoxicity against CD20 positive cancer cell lines.
  
  
  RESULTS
  Using frBsAbs specific for CD20 or HER2, the lytic activity of primary human T-cells expressing the BsAb-IR was specifically redirected against CD20+ leukemic cells or HER2+ epithelial cancer cells, respectively, while non-engineered T-cells were not activated. Notably, elimination of the CD28 costimulatory domain from the BsAb-IR construct significantly reduced frBsAb-redirected antitumor responses, confirming that frBsAbs are capable of delivering simultaneous TCR activation and costimulatory signals to BsAb-IR T-cells.
  
  
  CONCLUSIONS
  In summary, our results establish the proof of concept that the combination of BsAbs with optimized gene-engineered T-cells provides the opportunity to specify and augment tumor antigen-specific T-cell activation and may improve upon the early success of conventional BsAbs in cancer immunotherapy.
authors.affiliation: Department of Obstetrics and Gynecology, Ovarian Cancer Research Center, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA. katu@upenn.edu.
authors.forename: Katarzyna
authors.initials: K
authors.lastname: Urbanska
authors.affiliation: Department of Obstetrics and Gynecology, Ovarian Cancer Research Center, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA. ralynn@upenn.edu.
authors.forename: Rachel C
authors.initials: RC
authors.lastname: Lynn
authors.affiliation: Department of Obstetrics and Gynecology, Ovarian Cancer Research Center, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA. caitlin.stashwick@uphs.upenn.edu.
authors.forename: Caitlin
authors.initials: C
authors.lastname: Stashwick
authors.affiliation: Department of Oncology, Wayne State University, Detroit, MI, USA. thakur@karmanos.org.
authors.forename: Archana
authors.initials: A
authors.lastname: Thakur
authors.affiliation: Department of Oncology, Wayne State University, Detroit, MI, USA. luml@karmanos.org.
authors.forename: Lawrence G
authors.initials: LG
authors.lastname: Lum
authors.affiliation: Department of Pathology and Laboratory Medicine, Abramson Cancer Center, Perelman School of Medicine, University of Pennsylvania, 3400 Civic Center Blvd, Bldg 421, Smilow CTR, Rm 08-103, Philadelphia, PA, 19104-5156, USA. poda@mail.med.upenn.edu.|Department of Obstetrics and Gynecology, Ovarian Cancer Research Center, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA. poda@mail.med.upenn.edu.
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Powell
mesh_terms: D018033:Antibodies, Bispecific / Q000627:therapeutic use*; D002460:Cell Line; D005818:Genetic Engineering; D006801:Humans; D007167:Immunotherapy; D009369:Neoplasms / Q000628:therapy*; D013601:T-Lymphocytes / Q000276:immunology*
chemical_list: D018033:Antibodies, Bispecific