Natural Immune Reactivity-Associated Therapeutic Response in Patients with Metastatic Renal Cell Carcinoma Receiving Tumor-Infiltrating Lymphocytes and Interleukin-2-Based Therapy

Abstract

Combination therapy with systemically administered interleukin-2 (IL-2) and tumor infiltrating lymphocytes (TIL) demonstrates significant clinical activity in some patients with metastatic renal cell carcinoma (RCC). The objective of this study was to identify predictors of therapeutic response in patients with IL-2- and TIL-based immunotherapy. We characterized and compared immunologic properties of tumors, TILs, peripheral blood lymphocytes (PBLs) and sera of responding (R, n = 8) with nonresponding patients (NR, n = 9). Before undergoing nephrectomy, responding patients exhibited a higher percentage of circulating natural killer (NK) cells (CD56+ CD3-) (43 +/- 20%) as compared with nonresponders (18 +/- 16%) (p < 0.01). After nephrectomy, the CD56+ CD3-/CD56- CD3+ ratio in responding patients (pre: 2.60 +/- 2.24; post: 0.28 +/- 0.19; p < 0.05) significantly decreased and was similar to that of patients not responding to therapy (0.42 +/- 0.36). Sera from patients responding to immunotherapy, obtained before and after completion of therapy, contained natural killer (NK)-enhancing factor(s) that significantly enhanced the proliferation (3.2 x 10(3) +/- 25%/ 3.6 x 10(3) +/- 13% counts/min) and cytotoxicity [17.6 +/- 4.0/18.0 +/- 1.9 lytic units (LU)] of fresh PBLs as compared with normal serum (1.8 x 10(3) +/- 8% counts/min; 13.4 +/- 2.5 LU) or sera from nonresponders (1.6 x 10(3) +/- 25%/1.5 x 10(3) +/- 20% counts/min; 8.3 +/- 5.9/6.8 +/- 4.8 LU). In contrast to noncultured tumor suspension, IL-2 cultivation induced TIL growth, cytotoxicity, and multicytokine synthesis, and a complete clearance of tumor cells. No significant differences were observed between responders and nonresponders in the in vitro characteristics of tumor/TIL, which include the degree of intratumoral lymphocytic infiltrate, TIL expansion, specific lysis of autologous tumor, phenotype, expansion time, quantity of TIL infused, cytokine release, and degree of tumor aggressiveness. We conclude that clinical response to TIL and IL-2-based immunotherapy is associated with patients' baseline natural immune status. The percentage of circulating NK cells and the presence of serum NK-cell-enhancing factors may serve as potential predictors of response in patients with advanced RCC. The in vitro study of RCC-TIL suggests that activated TIL may provide a synergistic effect to that of administered IL-2 on activation of cellular immune response in situ, rendering a tumor eradication, while the clinical outcome is largely dependent on the pretreatment immune status of patient.