Increasing the purity, potency and specificity of ebv-specific T cells to improve the treatment of EBV-positive lymphoma

Results Although T2LP-specific EBVSTs could be generated from healthy-donors, we were unable to consistently generate EBVSTs with significant T2LP specificity from patients. We hypothesized that patient T cells were anergic to antigen expressed within tumors, and since IL-15 has been shown to rescue tolerant or anergic T cells, we replaced IL-4 with IL-15 (in combination with IL-7). This improved antigen specificity up to 10-fold. Further dose optimization showed significant advantages in cytolytic activity, proliferation and antigen specificity with higher dose of IL-15. We achieved higher fold expansion (3 fold mean increase in absolute EBVST numbers) and enhanced specificity for T2LPs (high vs. low IL-15 concentration: EBNA1: 156±218 vs. 13±33, LMP-1: 130±223 vs. 33±68, LMP-2: 518±466 vs. 88±122 and BARF-1: 109±147 vs. 24±40; SFC/10 cells; n=11). High dose IL-15 also increased the frequency of central memory T cells in the final T cell product (36.81±17 vs. 19.09±13 % vs.13.81±22 % (IL-15 Hi vs. IL-15 Lo vs. IL-4) in combination with Il-7). EBVSTs manufactured using all three conditions were used to treat 20 patients with multiply relapsed, EBVpositive lymphoma; as adjuvant therapy after stem cell transplantation or chemotherapy in 9 patients and as treatment for disease in 11 patients. All patients in remission at the time of infusion, remain in remission. Of patients with active disease at the time of infusion, there was one stable disease among 4 patients who received IL-4/7-expanded T cells, one PR and one CR in 3 patients who received low does IL-15/7-expanded T cells and two CRs and one PR among 4 patients whose T cells were expanded in high dose IL-15 (one is too early to assess).