Improved Homing of Antigen-Specific T Cells to Hodgkin’s Disease (HD) Tumor Cells by Forced Expression of CCR4 Receptor

One crucial requirement for the success of any adoptive T cell transfer is that the effector T cells should migrate efficiently to the tumor site. Such an effect has been documented following adoptive transfer of Epstein-Barr virus specific cytotoxic T cells (EBV-CTLs). Antigenic stimulus from (normal and malignant) cells persistently infected with EBV led to expansion and sustained survival, and was also associated with activity against the EBV+ HD tumors. Since most HD patients have tumors that are EBV- but CD30+, we attempted to extend this approach by incorporating a CD30 chimeric receptor (CD30CAR) into the EBV-CTLs. Pre-clinical animal studies showed that CD30CAR+ EBV-CTLs readily migrated to EBV+/CD30+ tumors, but had limited capacity to localize to EBV−/CD30+ tumor cells. The likeliest explanation for this observation is that EBV- HD tumors produce the chemokine TARC, which attracts Th2 and regulatory T cells, but has little effect on EBV-CTLs, since these express low levels of the TARC receptor, CCR4. We hypothesized that forced expression of CCR4 by redirected EBV-CTLs would improve their homing to the EBV−/CD30+ HD cells. The full length of CCR4 receptor was cloned into the SFG retroviral vector and used to transduce both activated T cells and EBV-CTLs obtained from 6 and 4 healthy donors, respectively. Expression of CCR4 was 12±8% on activated T cells (mainly on CD4+ cells, 12±6%) and 4±5% on EBV-CTLs. After transduction with a CCR4, but not a control vector, expression of CCR4 increased to 53±24% (CD4+ 27±15% and CD8+ 17±9%) on activated T cells and 30±19% on EBV-CTLs. We then evaluated the capacity of control and transgenic T cells and EBV-CTLs to migrate in response to TARC, using a trans-well migration assay. Migration was tested against different CD30+ tumor lines producing TARC at low (Karpas wild type, 2000pg/mL), measured by ELISA. The percent of cells migrating in the trans-well assay was significantly increased for CCR4 transgenic CD8+ selected T cells (54±11% with Karpas/TARC vs. 8±2% with media vs. 8±4% with Karpas-wt). Migration of control OKT3/28 blasts was less than 15% in all the conditions. Migration was significantly inhibited by the addition of antibody blocking TARC (7 days. These data suggest that the migration of CARCD30 EBV-CTL to EBV−/CD30+ HD can be augmented by co-expressing the CCR4 receptor.