BACKGROUND: There is currently no curative therapy for cutaneous T cell lymphoma 
(CTCL). New therapies are therefore needed. Telomerase, the enzyme that allows 
for unrestricted cell divisions of cancer cells, is a promising target for 
cancer therapy. The telomerase-specific peptide vaccination GV1001 has shown 
promising results in previous studies. Since telomerase is expressed in 
malignant cells of CTCL, GV1001 vaccination in CTCL is a promising new 
therapeutic approach.
OBJECTIVE: We sought to investigate the efficacy of GV1001 vaccination in CTCL 
patients and characterize the induced immune response.
METHODS: Six CTCL patients were vaccinated with the GV-peptide using 
granulocyte/macrophage colony-stimulating factor as adjuvant. Objective clinical 
response and the T cell response were assessed.
RESULTS: None of the patients demonstrated objective clinical response to the 
vaccination whereas one patient showed disease progression. 1/6 patients 
acquired a GV1001-specifc T cell response with a Th1 cytokine profile and 
expression of skin-homing receptors. This hTERT-specific T cell response was not 
associated with beneficial modulation of the tumor-infiltrating leukocytes. 
Furthermore, removal of regulatory T cells did not enhance responsiveness to 
GV1001 in vitro in any of the patients analyzed.
CONCLUSIONS: Our results suggest that the GV1001 vaccination is not effective in 
CTCL patients and disease progression in 1/6 patients raises concerns about its 
safety. By analyzing skin-homing properties of GV1001-specific T cells and the 
involvement of regulatory T cells we nevertheless provide insight into 
vaccine-induced immune responses which may help to improve vaccine strategies in 
CTCL.