Dendritic cells (DCs) are the professional antigen-presenting cells of the immune system. As such they are currently used in clinical vaccination protocols in cancer patients, and both immunological and clinical responses have been observed. For these therapies accurate delivery to target organs is essential. Correct delivery and subsequent migration of vaccinated DCs to regional lymph nodes is of paramount importance for effective stimulation of the immune system. Currently it is not known what the best route of administration is for DC vaccines.

Using magnetically labeled DCs, we investigate the potential of MRI cell tracking to monitor DC therapy. This is investigated in stage III/IV melanoma patients in whom a regional lymph node dissection is scheduled. Autologous monocyte-derived DCs are labeled with the clinically approved superparamagnetic iron oxide (SPIO) formulation Endorem and 111In-oxine and injected either in the skin or directly in lymph nodes under ultrasound guidance. Two days after vaccination patients are monitored with scintigraphy and MR imaging. Lymph nodes are then resected. Subsequently patients receive 3 more vaccination with DCs. During and after therapy immune responses against the used melanoma peptides are monitored.

Inclusion criteria:

Histologically documented evidence of melanoma

Stage III-IV melanoma according to the 2001 AJCC criteria

Radical lymph node dissection planned, either with curative (stage III) or palliative (stage IV) intent

Melanoma expressing gp100 (compulsory) and tyrosinase (non-compulsory)

HLA-A2.1 phenotype according to lymphocyte HLA typing

ECOG performance status 0-1, life expectancy > 3 months

Age 18-75 years

Interval since last prior chemotherapy, immunotherapy or radiotherapy at least 4 weeks, no residual toxicity of prior treatment.

WBC > 3.0 x 109/l, lymphocytes > 0.8 x 109/l, platelets > 100 x 109/l, serum creatinine < 150 μmol/l, serum bilirubin < 25 μmol/l

Written informed consent

Expected adequacy of follow-up

Exclusion criteria:

No clinical signs of CNS metastases, in patients with a clinical suspicion of other metastases diagnostic tests should be performed to exclude this.

No concomitant use of corticosteroids or other immunosuppressive agents

No history of second malignancy within the last 5 years. Adequately treated basal carcinoma of skin or carcinoma in situ of cervix is acceptable within this period

No serious concomitant disease, no active infections. No autoimmune disease or organ allografts, no clinical suspicion of HIV or Hepatitis B

No contra-indications for MRI-scanning: claustrophobia, pacemaker or pacemaker threads, cerebral clips or artificial heartvalves, internal hearing prosthesis No known allergy to shell fish (contains KLH)

No pregnant or lactating women