EVIDENCE FOR LOCAL AND SYSTEMIC ACTIVATION OF IMMUNE CELLS BY PERITUMORAL INJECTIONS OF INTERLEUKIN-2 IN PATIENTS WITH ADVANCED SQUAMOUS-CELL CARCINOMA OF THE HEAD AND NECK

Interleukin 2 (IL2) was injected peritumorally and intranodally in 36 patients with unresectable squamous cell carcinoma of the head and nec k enrolled in an Eastern Cooperative Oncology Group-sponsored phase Ib trial (EST P-Z388). Groups of 6 patients received escalating doses(20 0, 2 x 10(3), 2 x 10(4), 2 x 10(5), 2 x 10(6), and 4 x 10(6) units) of IL2 daily 5 times/week for 2 weeks. Tumor biopsies were obtained befo re and after IL2 therapy. Tumor tissue was provided for histology, and the remaining fresh tissue was divided for snap-freezing in -75-degre es-C and for separation of tumor-infiltrating lymphocytes (TIL) and tu mor cells. Immunophenotyping of TIL performed on cryostat sections of paired pre- and post-IL2 biopsy tissues showed increases after IL2 the rapy in the number of T-cells (P = 0.005), natural killer (NK; CD16+) cells (P = 0.0001), CD25+ cells (P = 0.004), and HLA-DR+ cells (P = 0. 001) accumulating in the tumor stroma. In the tumor parenchyma, NK cel ls (P = 0.0001) and HLA-DR+ cells (P = 0.003) were increased after IL2 therapy. The T:NK cell ratios in the tumor stroma and parenchyma were decreased after therapy, suggesting selective accumulation of NK cell s. By flow cytometry, TIL recovered from post-IL2 biopsy tissues were enriched (P < 0.05) in CD3-CD56+ (NK) cells. In situ hybridization wit h [S-35] cDNA probes for cytokines and IL2 receptors indicated that th e numbers of cells expressing mRNA for IL2, tumor necrosis factor alph a, IL1-beta, gamma-interferon, transforming growth factor beta, and IL 2 receptor p55 or p70 were increased in post-IL2 biopsy tissues as com pared to pre-IL2 tissues. Cytolytic activity of TIL isolated from post -IL2 tissues was also increased, as determined in 4-h Cr-51 release as says against K562 targets (12 +/- 3 mean lytic units/10(7) cells +/- S EM pre-IL2 versus 46 +/- 13 post-IL2; n = 16) and against autologous t umor (13 +/- 8 versus 68 +/- 26; n = 9). Fresh TIL of one clinical res ponder showed relatively high levels (195 lytic units) of autotumor cy totoxicity after IL2 therapy versus no activity prior to therapy. In t he blood, NK and lymphokine-activated killer cell activity, and percen tages of CD3-CD56+ NK cells and of activated (CD25+) T-lymphocytes wer e increased for all doses of IL2. A significant dose-response effect w as observed for the percentage of CD3-CD56+ NK cells and lymphokine ac tivated killer cell cytotoxicity against autologous tumor, with the hi ghest values observed at the two highest doses of IL2. Our data indica te that local as well as systemic activation of antitumor effector cel ls occurred during local administration of IL2 in patients with squamo us cell carcinoma of the head and neck.