Immunohistochemical expression of carbonic anhydrase IX assessed over time and during treatment in renal cell carcinoma

The immunotherapy cohort consisted of 120 patients treated with IL-2-based immunotherapy. All patients were prospectively enrolled in phase II trials and all had lowor intermediate-dose IL-2 with or without interferon α (IFNα ) and histaminedihydrochloride [7]. Paraffin-embedded baseline and on-treatment tumour biopsy material was available from 52 of these 120 patients. Among the 52 patients, 23 patients had three biopsies evaluable and 29 had two evaluable biopsies. The core-needle biopsies (18 G cutting-needle) were collected by standard ultrasound-guided procedures. Biopsies were taken before treatment (baseline) and at predefined time points according to the treatment schedule (on treatment), to coincide with the outpatient visits. As the biopsies derive from different treatment schedules, the time points vary slightly. The first, second and third biopsy was always taken from the same tumour site, either the primary tumour or a metastatic lesion. All studies were conducted in accordance with the Helsinki declaration II and approved by the local ethics committee and the Danish Medical Agency.