Detection of p53 gene change and serum antibody level in phase II clinical trial of ad p53 gene therapy

Abstract

To determine the alteration of p53 gene in tumor tissues and to monitor the immunoresponsiveness to anti adenovirus in patients following treatment of recombinant adenovirus-p53 (Adp53, SBN-1) combined with radiation. Tumor tissues were collected from 22 patients with malignant tumors at advanced stage before and after treatment with recombinant adenovirus-p53 (Adp53, SBN-1) combined with radiation. Immunohistochemistry was used to detect the p53 expression. Microdissection, PCR, and denaturation high performance liquid chromatography (DHPLC), and DNA sequencing were used to detect the mutation of p53 gene. The levels of the anti-adenovirus antibody SBN-1, IgG and IgM in the serum were detected by using ELISA. p53 positive staining was shown in the nuclei of tumor cells in 6 of 15 tumor samples showing the increase of stability of protein caused by gene mutation. DHPLC and DNA sequencing showed point mutation in 7 of 22 tumor samples. Six of the 7 cases with p53 gene mutation showed complete and partial remission at the degree > 50%, and the 8 cases without p53 gene mutation only showed partial remission or stability of condition. The IgG positive rate was 50% (8/ 16), showing that 50% of the patients had been infected by adenovirus (mainly the types 3, 7, and 11) before. The IgM positive rate was 6% (1/16), showing that most of the patients had not been infected by adenovirus (mainly the types 3, 7, and 11) at that time. The anti-SBN-1 antibody was negative in all patients before the rAd-53 therapy and became positive since the 4th week after the beginning of treatment and the intensity of positivity increased along with the time. An effective gene diagnosis system for detecting the p53 gene alteration has been developed.