Studies on DC subsets in blood and organs in man are vital and likely to be demanding. Conventional vaccination” strategies in contrast do not allow precise targeting. Many strategies have been attempted to make such vaccines nevertheless work, for example, through the use of antigen in various formats in conjunction with

novel adjuvants. Recombinant vectors (which may preferentially reach DC) and prime-boost regimens are also explored as approaches to optimization (for review see 22). I would like to address a few items that are of general relevance: (i) A recent alarming finding is that patients treated check details with either Canvaxin™ (made up of three melanoma cell line lysates+BCG) or a GM-2+QS21 vaccine (composed of a ganglioside antigen+saponin as adjuvant) experienced worse clinical outcome than the control arm in large phase III melanoma

trials 23. Immunomonitoring data are currently not available in order to rationalize the negative results (e.g. tolerance induction because of insufficient DC targeting and suboptimal maturation?). These results, however, caution that in case of vaccines, clinically promising phase II data (particularly if based on comparison with historical controls) have to be supplemented by solid immunomonitoring and demonstration of T-cell (not only B-cell) immunogenicity before going on to phase III studies, in order to avoid exacerbating patients’ disease. DC BIBW2992 in vitro vaccination,” i.e. active immunization by adoptive transfer of DC, either enriched/isolated from peripheral blood or generated ex vivo from (CD34+ or more often CD14+) precursors offers the possibility to monitor and address variables crucial for an optimized T-cell immunogenicity, notably aspects of DC biology most relevant for immunogenicity (e.g. DC type, maturation status, migratory

capacity, and antigen loading) as well as important vaccination logistics such as DC number, route, and frequency of vaccination. The first DC vaccination study was published in 1996 and used rare DC isolated directly ex vivo from peripheral blood to immunize B-cell lymphoma patients against their tumor-specific idiotype protein 31. By March 2010, almost 300 papers have Benzatropine been published reporting on 4422 patients treated (not all under Good Clinical Practice (GCP) conditions: primarily melanoma 32, 33 and prostate cancer 34 patients – 1301 and 510 patients, respectively). Most trials employed monocyte-derived DC (MoDC), which were most often generated from monocytes by culture in GM-CSF+IL-4 over approximately 6 days to obtain immature DC, followed by exposure to monocyte-conditioned medium or its mimic (cocktail composed of TNF-α+IL-1β+IL-6+PGE2) for 1–2 days, to yield “cocktail”-matured DC. Short-term culture methods have also been described 35, but appears to be more variable in inducing stably differentiated DC and probably for this reason, have not been explored extensively in trials.