NK cells mediate Flt3 ligand-induced protection of dendritic cell precursors in vivo from the inhibition by prostate carcinoma in the murine bone marrow metastasis model

Multiple observations suggest that suppression of the dendritic cell (DC) system might be one of the mechanisms used by the tumors to escape immune response. However, no in vivo data are available to support these in vitro observations. Here we have shown that murine prostate cancer inhibits DC generation (dendropoiesis) from the bone marrow precursors in the in vivo model in mice injected intrafemorally with RM1 prostate adenocarcinoma cells. Phenotyping of DC, generated from in vivo RM1-treated bone marrow cells, revealed a significant inhibition of dendropoiesis assessed as a percentage of CD11c+MHCII+, CD11c+CD86+, and CD11c+CD80+ cells. The stimulatory capacity of these DCs to induce T cell proliferation was also markedly decreased. Notably, Flt3 ligand-based therapy reversed the inhibitory effects of prostate cancer on dendropoiesis in vivo in wild-type and C.B-17 SCID (T and B cell deficient) mice, but not in SCID beige (T, B, and NK cell deficient) animals, suggesting a key role of NK cells in Flt3 ligand-mediated protection of dendropoiesis from tumor-induced inhibition in vivo. Thus, these data demonstrate that prostate cancer inhibits DC hematopoietic precursors in vivo in the bone marrow and this effect could be abolished by a systemic administration of growth factor Flt3 ligand.     

Phase I and pharmacodynamic study of 17-(allylamino)-17-demethoxygeldanamycin in adult patients with refractory advanced cancers.

PURPOSE: The primary objective was to establish the dose-limiting toxicity (DLT) and recommended phase II dose of 17-(allylamino)-17-demethoxygeldanamycin (17AAG) given twice a week. EXPERIMENTAL DESIGN: Escalating doses of 17AAG were given i.v. to cohorts of three to six patients. Dose levels for schedule A (twice weekly x 3 weeks, every 4 weeks) were 100, 125, 150, 175, and 200 mg/m(2) and for schedule B (twice weekly x 2 weeks, every 3 weeks) were 150, 200, and 250 mg/m(2). Peripheral blood mononuclear cells (PBMC) were collected for assessment of heat shock protein (HSP) 90 and HSP90 client proteins. RESULTS: Forty-four patients were enrolled, 32 on schedule A and 12 on schedule B. On schedule A at 200 mg/m(2), DLTs were seen in two of six patients (one grade 3 thrombocytopenia and one grade 3 abdominal pain). On schedule B, both patients treated at 250 mg/m(2) developed DLT (grade 3 headache with nausea/vomiting). Grade 3/4 toxicities seen in >5% of patients were reversible elevations of liver enzymes (47%), nausea (9%), vomiting (9%), and headache (5%). No objective tumor responses were observed. The only consistent change in PBMC proteins monitored was a 0.8- to 30-fold increase in HSP70 concentrations, but these were not dose dependent. The increase in PBMC HSP70 persisted throughout the entire cycle of treatment but returned to baseline between last 17AAG dose of cycle 1 and first 17AAG dose of cycle 2. CONCLUSIONS: The recommended phase II doses of 17AAG are 175 to 200 mg/m(2) when given twice a week and consistently cause elevations in PBMC HSP70.     

Effects of in vivo recombinant methionyl human granulocyte colony- stimulating factor on the neutrophil response and peripheral blood colony-forming cells in healthy young and elderly adult volunteers

Recombinant granulocyte colony stimulating factor (G-CSF) was administered daily for 14 days to healthy young (Y) (20 to 30 years) and elderly (O) (70 to 80 years) volunteers to evaluate the effects of age on the neutrophil (polymorphonuclear leukocytes, PMN) responses. Thirty-eight volunteers were randomized to receive 0 micrograms, 30 micrograms, or 300 micrograms per day. Baseline neutrophil counts (ANC), peak ANCs, and the rate of attaining the peak ANC were similar in both age groups at both doses. The peak ANC was increased 5-fold at 30 micrograms and 15-fold at 300 micrograms in both the young and elderly. Daily tests of PMN function, as measured by an automated chemiluminescence system, showed nearly identical responses to several agonists for both age groups. Marrow proliferative activity as reflected by the percentage of cells in the marrow neutrophil mitotic pool also increased similarly for both age groups at both doses. In contrast, there was an age-related change in blood colony formation as measured by the blood CFU-GM assay. Compared with controls at the 30 micrograms dose, mean colony formation was increased 2-fold in the young versus no change in the elderly and at the 300 micrograms dose 24- fold in the young versus 12-fold in the elderly. These studies indicate that neutrophil responses to rhG-CSF are equivalent in healthy young and elderly volunteers but the mobilization of progenitor cells, as measured by the CFU-GM assay appears to differ substantially.