Increases in serum TARC/CCL17 levels are associated with progression-free survival in advanced melanoma patients in response to dendritic cell-based immunotherapy.

INTRODUCTION: Changes in the levels of serum cytokines and growth factors are associated with response to therapy. We examined cytokine, chemokine, and growth factor levels in serum collected from normal volunteers or metastatic melanoma patients receiving dendritic cell-based immunotherapy. MATERIALS AND METHODS: Using an array for 42 cytokines, chemokines, or growth factors, sera from normal controls and metastatic melanoma patients at baseline and week 4 were analyzed for qualitative changes. Quantitative determination of the levels of the chemokine thymus and activation-regulated chemokine (TARC/CCL17) was determined by enzyme-linked immunosorbent assay (ELISA). RESULTS: Significant qualitative differences were noted in serum cytokine, chemokine, and growth factor levels of metastatic melanoma patients versus the normal controls at baseline. The results also demonstrated a significant decrease in the level of angiogenin (P = 0.026) and a significant increase in TARC/CCLl7 (P = 0.008) from week 0 to week 4 which was associated with improved overall survival (P = 0.059). Higher TARC/CCL17 levels were observed by ELISA at week 4 and a log-rank comparison revealed a significant association between high serum TARC/CCL17 levels at week 4 and progression-free survival (P = 0.005). Receiver-operator characteristic analysis revealed that week 4 serum TARC/CCL17 levels were predictive of progression-free and overall survival, indicating that serum TARC/CCL17 might be of predictive value of response to dendritic cell-based anti-melanoma immunotherapy.

Human allogeneic and murine xenogeneic dendritic cells are cytotoxic to human tumor cells via two distinct pathways.

Human monocyte-derived dendritic cells (DCs), stimulated with granulocyte-macrophage colony-stimulating factor and interleukin-4 for 1 week, major histocompatibility complex killed human tumor cells in 24-hour cytotoxicity assays. These immature DCs were >90% CD11c, major histocompatibility complex class II(+), but <1% were CD83(+) cells. Within 24 hours, these DCs ingested tumor membranes. The DC cells also lysed Jurkat lymphoma cells, but not Jurkat cells genetically knocked out of the Fas-associated death domain (FADD) or caspase-8. DC2.4, a cloned murine DC line, also displayed cytotoxicity toward U-251 cells, although these murine DCs were less potent than human DC. DC2.4 did not kill Jurkat cells, rat T9 glioma cells, or human Caco-2 colon cancer cells, suggesting that a unique receptor or ligand interaction exists between the DC and U-251 cells. This interaction was destroyed by the paraformaldehyde fixation of the tumor cells. Supernatants from the cultures of DC2.4 and tumor cells were analyzed by the Griess reaction for signs of nitric oxide (NO) production. Augmented NO production occurred in DC2.4/U-251 and DC2.4/Jurkat cultures but was not seen in the human DC/U-251 cultures. These studies suggest that DCs possess different mechanisms of tumoricidal activity.

Lack of elevation of serum S100B in patients with metastatic melanoma as a predictor of outcome after induction with an autologous vaccine of proliferating tumor cells and dendritic cells.

Serum levels of S100B and/or lactate dehydrogenase (LDH) are putative tumor markers in melanoma. Early changes in such markers may correlate with a positive immune response to vaccine therapy. In patients with metastatic melanoma, S100B and LDH serum levels were measured at baseline, and 1 week after 3 weekly subcutaneous injections of investigational, patient-specific vaccines consisting of autologous dendritic cells loaded with antigens from irradiated proliferating autologous tumor cells, and suspended in granulocyte macrophage colony-stimulating factor. There was a poor correlation between S100B and LDH levels at baseline (p = 0.324). Fourteen (14) patients with measurable disease had higher S100B (p = 0.0456) and LDH (p = 0.0013) levels than 31 patients who lacked measurable disease at that time. Fourteen (14) deceased patients (median survival, 13 months) had a mean baseline S100B of 0.62 mug/L (95% confidence interval [CI] 0.00-1.66) and LDH of 815 U/L (95% CI 222-1408); 31 surviving patients (median follow-up, 35.4 months) had mean S100B of 0.07 mug/L (95% CI 0.00-0.23; p = 0.006) and LDH of 442 U/L (95% CI 296-588; p = 0.002). Elevated baseline levels of LDH and S100B were each predictive of inferior progression-free survival (PFS) and overall survival (OS) (both p < 0.0001), but S100B was a better predictor for PFS than LDH. Changes in LDH between baseline and week 4 were not predictive of survival, but an increase in S100B predicted for inferior OS ( p = 0.039). Both LDH and S100B are predictive tumor markers in patients with metastatic melanoma. This is the first study to examine the changes in serum levels of LDH and S100B in response to an autologous tumor-cell vaccine.