In Vivo Expansion And Activation Of T Cells As Immunotherapy For Refractory Neuroblastoma: A Phase 1 Study

Introduction:CD3+ + T cells comprise 2% to 5% of circulating T cells with V9V2+ cells the dominant circulating subtype. V9V2+ cells recognize non-peptide phosphoantigens and stress-associated NKG2D ligands expressed on malignant cells. Strategies that incorporate the tumoricidal properties of T cells represent a promising immunotherapeutic strategy for treatment of solid malignancies including neuroblastoma (NB). In this prospective, non-randomized Phase I trial, we assessed whether circulating V9V2+ cells could be safely expanded using intravenous ZOL (Zoledronate [Zometa((R))]) and subcutaneous Interleukin-2 (IL-2) in patients with refractory NB.Methods:Patients 2 to 21 years of age with refractory neuroblastoma with no known curative therapeutic options received ZOL on day 1, and IL-2 on days 1 to 5 and 15 to 19 of each 28-day cycle (n = 4). Lymphocyte immunophenotyping was assessed weekly. Immunophenotyping studies from the treatment group were compared with healthy pediatric controls (n = 16; range, 5y-15y) and of untreated NB disease controls (n = 9; range, 4m-18y).Results:Treatment was well tolerated with no unexpected grade 3 and 4 toxicities. Lymphocyte subset counts did not differ significantly between volunteers and disease controls with the exception of + T cell counts that were significantly higher in healthy volunteers (212+93 vs. 89+42, P = 0.05). Study patients showed increases in circulating + T cell count (3-10 fold) after the first week, increasing into the range seen in healthy volunteers (125+37, P = 0.1940). Interestingly, all ZOL+IL-2 treated patients showed significant increases in CD3+CD4+CD27(hi)CD127(dim) T cells that rose weekly in 2 patients throughout the 4 weeks of observation (maximum 41% and 24% of total CD3+CD4+ T cells, respectively).Conclusions:In summary, combined ZOL and IL-2 is well tolerated and restored + T cell counts to the normal range with a moderate expansion of Natural Killer cells. Progressive increases in circulating CD4+ T cells with a regulatory phenotype cells may offset beneficial effects of this therapy.