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The targeting of gene transfer at the cell-entry level is one of the most attractive challenges in vector development. However, attempts to redirect adenovirus vectors to alternative receptors by engineering the capsid-coding region have shown limited success, because the proper targeting ligands on the cells of interest are generally unknown. To overcome this limitation, we have constructed a random peptide library displayed on the adenoviral fiber knob, and have successfully selected targeted vectors by screening the library on cancer cell lines in vitro. The infection of targeted vectors was considered to be mediated by specific receptors on target cells. However, the expression levels and kinds of cell surface receptors may be substantially different between in vitro culture and in vivo tumor tissue. Here, we screened the peptide display-adenovirus library in the peritoneal dissemination model of AsPC-1 pancreatic cancer cells. The vector displaying a selected peptide (PFWSGAV) showed higher infectivity in the AsPC-1 peritoneal tumors but not in organs and other peritoneal tumors as compared with a non-targeted vector. Furthermore, the infectivity of the PFWSGAV-displaying vector for AsPC-1 peritoneal tumors was significantly higher than that of a vector displaying a peptide selected by in vitro screening, indicating the usefulness of in vivo screening in exploring the targeting vectors. This vector-screening system can facilitate the development of targeted adenovirus vectors for a variety of applications in medicine.

Multiple primitive intracranial tumors with different histological characteristics are uncommon. Although coexistence of a medulloblastoma with glial tumors has been reported in children, medulloblastoma is rarely found in adults, especially those older than 40 years of age. We present an extremely rare case of a medulloblastoma developing in a 40-year-old male undergoing maintenance chemotherapy for anaplastic astrocytoma for 21 months after radiotherapy. Initially, he complained of intractable epilepsy characterized by complex partial seizures. Magnetic resonance imaging (MRI) revealed a slightly enhanced mass lesion in the left insula region. He underwent subtotal removal of the tumor and it was histologically diagnosed as anaplastic astrocytoma. After 19 months of treatment with temozolomide (TMZ) and radiotherapy, he presented with vertigo and headache. A homogeneously enhanced mass had developed in the left cerebellar hemisphere. He received gross total resection of the second tumor, pathologically diagnosed as medulloblastoma. In conclusion, this is the first case report of an adult medulloblastoma coexisting with anaplastic astrocytoma.