[ off topic, ignore ]
just parking stuff.......
[PROC. AMER. ASSOC. CANCER RES. 40, March 1999]
Copyright © 1999 by the American Association for Cancer Research
#577 Prostate tumor-specific cytolysis and tumor eradication by intravenous administration of CN787, an
attenuated replication competent adenovirus containing E3. Yu, D-C. and Henderson, D. R. Calydon, Inc.,
Sunnyvale, CA 94089. Metastatic prostate cancer is the second leading cause of U.S. male cancer-related deaths
killing an estimated 39,200 men annually. We previously described CN706, an attenuated replication competent
adenovirus (ARCATM), that eradicates tumors in nude mice with a single intratumoral injection, and we recently
described CN764, an improved ARCATM with 10,000:1 specificity for PSA(+) cells. In this communication we
report an improved virus, CN787, that retains the high selective cytotoxicity of CN764, but has improved anti-tumor
activity. CN787 was constructed by inserting the rat probasin (PB) promoter (-426 to +28) so as to drive the Ad5
E1A genes, and the minimal enhancer/promoter elements derived from the 5'-flanking region of the PSA gene (PSE)
so as to drive the Ad5 E1B genes, coupled with re-introduction of the Ad5 E3 region. In vitro studies showed that
CN787 preferentially replicates 10,000:1 in PSA(+) prostate cells (LNCaP) in comparison to a PSA(-) normal human
diploid cell strain derived from microvascular endothelial cells (hMVEC). Improved in vivo anti-tumor activity was
achieved by incorporation of the Ad5 E3 region. In vitro, CN787, compared to its E3-deleted prostate-specific virus
counterpart CN739, forms larger plaques, produces a higher virus yield, and mediates a more rapid release of
adenovirus progeny from infected cells. In vivo CN787 eradicates tumors more efficiently than CN739. In vivo
studies of CN787 in the nu/nu mouse LNCaP xenograft model shows that three tail vein intravenous administrations
within one week (1 x 1011 particles per administration) completely eliminated 300ul subcutaneous LNCaP tumors (0.3
x 109 cells) and abolished PSA production.
#578 Multimodality adenovirus vectors for cancer gene therapy. Wu, X., Okoh, V.O., Goldsmith, K., and
Garver, R.I., Jr. University of Alabama at Birmingham, Birmingham, AL 35294.
Both E1A and E1B gene products of adenoviruses (Ad) are required for Ad replication in normal cells. However, the
requirement for all E1B products is often dispensable in tumor cells. E1A can induce apoptosis and transactivate the
cytomegalovirus (CMV) immediate early gene promoter. We hypothesized that a recombinant adenovirus containing a
native E1A transcription unit would selectively replicate in neoplastic tissues and increase transgene expression. A
novel recombinant adenoviral (rAd) vector, AdE1A-tk, was constructed to contain a full E1A transcription unit and a
transgene expression cassette containing HSV-tk gene driven by the CMV promoter. Western blot analysis revealed
enhanced expression of E1A proteins and HSV-TK transgenic protein. Functional assays showed that the
transactivation activity of E1A was conserved in AdE1A-tk. In vitro replication assays demonstrated that AdE1A-tk
selectively replicated in lung cancer cell lines A549 and H1299 with 3-4 logs higher than in normal human bronchial
epithelium (NHBE). AdE1A-tk was also highly cytotoxic in cancer cell lines including A549 and H1299. Severe
cytopathic effect (CPE) was observed 48 hours postinfection at MOI 1 and the viable cell counts were reduced 55%.
This cytotoxicity was further augmented by addition of prodrug ganciclovir (GCV). It is concluded from these data that
AdE1A-tk (1) can selectively replicate in neoplastic cells, (2) is cytotoxic on the basis of both E1A and HSV-tk
products, and thus (3) may enhance the therapeutic efficacy for cancer gene therapy.
[PROC. AMER. ASSOC. CANCER RES. 40, March 1999]
Copyright © 1999 by the American Association for Cancer Research
#4156 Synergism of ionizing radiation and gene therapy with the replication competent CN706 adenovirus
in the LAPC-4 prostate cancer cell line. Ramakrishna, N.R., Rioseco-Camacho, N., Sawyers, C.L., Yu, D.C.,
Henderson, D., Simons, J.W., and DeWeese, T.L. The Johns Hopkins University Oncology Center, Baltimore, MD
21287; University of California Los Angeles School of Medicine, Los Angeles, CA 90095 and Calydon
Corporation, Sunnyvale, CA 94025.
A replication competent adenovirus CN706 preferentially replicates in PSA-positive prostate cancer cells. This vector
is being tested in a phase I clinical trial utilizing stereotactic intraprostatic injection. We tested whether the efficacy
might be augmented by combining cytoreductive gene therapy using CN706 with ionizing radiation in the PSA-positive
LAPC-4 prostate cancer cell line. XRT was administered to LAPC-4 cells in doses of 1-4 Gy prior to or following
viral infection with 0.1-10 moi of CN706. The combined effects of XRT and virus on cell growth were measured with
a growth inhibition assay. Infection of the androgen receptor wild-type LAPC-4 cells with CN706 results in dose
dependent growth inhibition and cell death. The use of virus alone or XRT alone resulted in decreased cell ATP to
approximately 35% of that seen in untreated controls at 10 days post-infection. The combination of XRT and virus
resulted in a decrease in cell ATP to approximately 8% of the untreated controls. The effect of the combination of
radiation and viral infection on growth inhibition was approximately 35% greater than expected if the actions of both
agents were purely additive. These data suggest that a combination of radiation and oncolytic virus may result in
synergistic tumoricidal effects. Isobologram analyses and further experiments are underway to determine the underlying
mechanisms for this interaction.
|
