WT1 peptide-loaded dendritic cell vaccine (Medinet)

Leukocyte apheresis is necessary in various cellular therapies. However, maintenance of a stable flow rate during leukocyte apheresis is often difficult, even in patients or donors without major problems. Despite this, predictive methods and evidence regarding the reality of the situation are limited. We conducted a retrospective analysis involving adult patients who required leukocyte apheresis for the treatment of neoplasms using WT1‐pulsed dendritic cell vaccine. Monocytes were separated from apheresis products to obtain dendritic cells. All the patients were pre‐evaluated based on laboratory and chest X‐ray findings and subjected to an identical apheresis procedure. The occurrence of poor blood collecting flow during leukocyte apheresis was monitored, and the frequency, clinical information, and associated risk factors were analyzed. Among 160 cases, poor blood collecting flow was observed in 53 cases (33.1%) in a median time of 54 min (range, 2–127 min) post‐initiation of leukocyte apheresis. Owing to difficulty in obtaining higher collecting flow, a longer procedure time was required, and in some cases, the scheduled apheresis cycles could not be completed. Consequently, the number of harvested monocytes was low. Multivariable analysis indicated that female patients have an increased risk of poor inlet flow rate. Furthermore, prolonged QT dispersion (QTD) calculated using Bazett's formula was found to be a risk factor. Although the patients did not present any major problems during leukocyte apheresis, poor blood collecting flow was observed in some cases. Sex and pre‐evaluated QTD might be useful predictors for these cases; however, further prospective evaluation is necessary.

Wilms' tumor 1 (WT1) is a tumor-associated antigen highly expressed in cancer. We examined the safety of WT1-peptide pulsed dendritic cell (WT1-DC) vaccine in combination with chemotherapy in patients with surgically resected pancreatic cancer.

Eight patients with resectable pancreatic cancer undergoing surgery either combined with S-1 or S-1 plus gemcitabine therapy were enrolled. Immunohistochemical analysis of WT1 was performed in 34 cases of pancreatic cancer.

No serious side-effects were observed, except grade I fever in five and grade I reactions at the injection site in all patients. WT1-specific cytotoxic T-lymphocytes were detected in seven patients, and WT1 and human leukocyte antigen class I antigens were positive in all 34 cases.

Our study clarified the safety and potential acquisition of immunity after vaccination targeting WT1. Further efficacy of WT1-DC vaccine to improve prognosis would be determined by a prospective clinical trial for resectable pancreatic cancer.