The team evaluated preoperative dendritic cell (DC) mobilization and tumor infiltration after administration of Flt3 ligand (Flt3L) to metastatic colon cancer patients.
Their findings have been reported in December's Journal of Clinical Oncology.
Twelve patients with colon cancer, metastatic to the liver or lung, were given Flt3L (20 µg/kg/d subcutaneously for 14 days for 1-3 cycles at monthly intervals) before attempted resection of metastases.
Flt3L increased dendritic cells in peripheral blood from 2.4% to 8.8%
The group discovered that after Flt3L administration, on average, the total number of leukocytes in the peripheral blood increased from 5.9 to 11.2 x 103/mm3. The percentage of CD11c+CD14- DCs in PBMCs increased from 2.4 per cent to 8.8 per cent.
Delayed-type hypersensitivity (DTH) responses to recall antigens (Candida, mumps, and tetanus) showed marginally significant increases in reactivity after Flt3L administration.
An increase in the number of DCs was observed at the periphery of the tumors of patients who had received Flt3L, compared with those of patients who had not.
Dr Michael Morse concluded that, "Flt3L is capable of mobilizing DCs into the peripheral blood of patients with metastatic colon cancer and may be associated with increases in DC infiltration in the peritumoral regions.
"The use of Flt3L to increase circulating DCs for cancer immunotherapy should be considered."