Scientific Abstract 
SCIENTIFIC ABSTRACT 
Colorectal cancer (CRC) strikes approximately 150,000 P^ems 
States with sreater than 40% of these patients destined to die of the disease despite current 
medical management Death is commonly due to liver metastases with sequeke including 
progressive liver dysfunction. Hepatocellular cancer (HCC) strikes approximately 8,000 
patients per year in the United States and about 1.25 million worldwide. Most patients 
present with tumors that are unresectable and incurable with existing therapies. The median 
survival for CRC patients after diagnosis with liver metastases, and for HCC patients, is 
approximately 6 months or less. 
The human p53 gene is a tumor suppressor gene involved in the control of cell 
proliferadon. Loss of wild-type p53 function is associated with the uncontrolled growth of 
manv types of human cancers. The reintroduction and expression of wild-type p53 into 
p53-altered tumor cells has been shown to suppress tumor growth or induce apoptosis m 
both in vitro and in vivo models. It is estimated that greater than 50% of CRC tumors and 
between 30 to 50% of all HCC tumors have p53 alterations. 
This study seeks to evaluate the safety, biological efficacy and the effect of dose of ACN53 
treatment. ACN53 is a recombinant adenoviral vector containing the wild-type human p53 
gene. ACN53 will be administered by infusion via the hepatic artery, for the regional gene 
therapy of malignant liver tumors. Study patients will have incurable metastatic (CRC) 
malignant tumors of the liver or primary (HCC) cancer, with evidence of p53 alteration in 
their liver tumors. In vitro studies have demonstrated p53-specific antiproliferative effects 
of ACN53 on human HCC and CRC cells and in vivo studies have demonstrated p53- 
specific antiproliferative effects of ACN53 on human CRC cells. 
The ACN53 construct is a recombinant, replication-defective, adenovirus derived from 
adenovirus serotype 5 (Ad5), subgroup C. The adenoviral Ela, Elb and protein IX coding 
sequences are deleted and replaced with the p53 expression cassette. The deleted El region 
is necessary for viral replication. The virus is additionally deleted for 1.9 kb of DNA 
sequence in Early Region 3, including that sequence encoding the gpl9K protein. The p53 
expression cassette contains the human cytomegalovirus immediate early promoter- 
enhancer, the adenovirus type 2 tripartite leader sequence and a sequence encoding wild- 
ty pe p53 protein. The human cytomegalovirus immediate early promoter-enhancer directs 
robust gene expression and the adenovirus type 2 tripartite leader sequence enhances 
translational efficiency. Polyadenylation is regulated by the Elb and pIX polyadenylation 
signal. All other regulatory elements and replication origins within ACN53 are endogenous 
r . j Ad5. The recombinant adenovirus is similar to other adenoviral vectors reviewed by the 
RAC and the FDA except that it contains the additional deletion of the pIX coding 
sequence. The deletion in the pIX coding sequence is expected to reduce the frequency of 
replication competent adenovirus arising during virus production by reducing the sequence 
identity with the El sequences of the 293 production cell line. 
: he study design is an open-label, non-randomized, single-dose, dose escalation Phase I 
clinical trial anticipated to involve a maximum of 27 patients. ACN53 will be administered 
in escalating doses to successive cohorts of patients until the maximum tolerated dose is 
determined. Regional ACN53 therapy will be administered as a single bolus infusion via 
hepatic artery catheter. The route of administration of ACN53 via hepatic artery infusion is 
designed to maximize gene therapy exposure to the malignant tumors while minimizing 
exposure to normal tissues outside the liver. The clinical protocol is designed to monitor 
treatment toxicity. Another objective is to evaluate the biological efficacy, including 
efficiency and stability of gene transfer by analysis of tumor tissues following therapy. As 
an important part of this objective the phaimacokinetics of ACN53 will be studied. Clinical 
c ^^!? cc an ti- tumor efficacy will also be collected. In addition, the safety and efficacy 
of different doses levels of ACN53 will be studied. 
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Recombinant DNA Research, Volume 20 
