Combination gene therapy with adenoviral vector-mediated HSV-tk+GCV and IL-12 in an orthotopic mouse model for prostate cancer

Abstract

We previously demonstrated signi®cant therapeutic activities associated with adenoviral vector-mediated Herpes Simplex Virus/thymidine kinase (AdHSV-tk) with ganciclovir (GCV) in situ gene therapy in the RM-1 orthotopic mouse prostate cancer model and interleukin-12 (AdmIL-12) in situ gene therapy in the RM-9 orthotopic mouse prostate model for prostate cancer. In both protocols, local cytotoxicity and activities against pre-established lung metastases were demonstrated. To test whether combined AdHSV-tk GCV IL-12 gene therapy would lead to enhanced therapeutic effects when compared to either treatment alone, we used RM-9 mouse prostate cancer cells in both orthotopic and preestablished lung metastases models of prostate cancer. Combined treatment with a single injection of optimal doses of AdHSV-tk GCV or AdmIL-12 led to signi®cantly increased suppression of orthotopic tumor growth. IL-12 gene therapy alone was more effective than AdHSV-tk GCV in suppressing spontaneous lymph node metastases and pre-established lung metastases but combination gene therapy did not result in additional anti-metastatic activities. Combination gene therapy also did not achieve signi®cantly better animal survival compared to AdHSV-tk GCV or AdmIL-12 alone. Analysis of localized antitumor activities demonstrated that AdHSV-tk GCV therapy induced higher levels of necrosis compared to AdmIL-12 or combination therapy. However, both treatments alone and combination therapy produced similar increases in apoptotic index. To address the possible mechanisms of locally co-operative cytotoxic activities, we analyzed the systemic natural killer (NK) response and the numbers of tumor-in®ltrating immune cells using quantitative immunohistochemical analysis. AdHSV-tk GCV therapy alone led to detectable increases in iNOS-positive cells, CD4 and CD8 T-cells and moderately increased numbers of F4/80 (macrophage selective)-positive cells within treated tumors. In contrast, AdmIL-12 elicited a highly robust pattern of tumor in®ltration for all four of these immune cells that was in general mimicked by combination therapy. Further analysis of the accumulation of transforming growth factor-b1 (TGF-b1) immunohistochemical staining demonstrated that AdHSV-tk GCV treatment, but not AdmIL-12 treatment, produced cancer cell-associated increases in this cytokine relative to control Ad-b-gal injections. Interestingly, local injection with AdHSV-tk GCV induced signi®cant splenocyte-derived NK cell cytolytic

Route of administration influences the antitumor effects of bone marrow-derived dendritic cells engineered to produce interleukin-12 in a metastatic mouse prostate cancer model

“…2,19,20 Further, we demonstrated that in situ adenoviral vector-mediated IL-12 combined with B7-1 gene therapy was significantly more effective in delaying orthotopic tumor growth and inducing partial or complete regression than adenoviral vector-mediated IL-12 alone. 19 Since DC are potent professional APC with the capacity to induce tumorspecific CTL activity and potent antitumor effects, we reasoned that IL-12 gene-modified DC may offer an alternative and potentially more potent immuno-gene therapy by providing enhanced APC functions.…”

The antitumor activity of TRAIL and IL-24 with replicating oncolytic adenovirus in colorectal cancer

“…The combination of Ad-IL-2 and Ad-IL-12, 41 Ad-Bax and Ad-TRAIL, 30 Ad-tk and immunotherapy or antiangiogenic therapy has been studied. [42][43][44][45] All the above experiments have got good antitumor effect, but experimental data about complete eradication of the tumor masses in all studied animals have not been published. In this study, we constructed tumor selective replicating adenoviral vector ZD55 that can replicate and induce CPE similar to ONYX-015 and two therapeutic genes IL-24 and TRAIL were incorporated into this vector separately.…”

Therapeutic effects of adoptive splenocyte transfer following in situ AdIL-12 gene therapy in a mouse prostate cancer model

“…Enhancement of a cellular immune response through the direct delivery of specific immunostimulatory cytokine genes into prostate tumors has antitumor and antimetastatic effects in preclinical models. [16][17][18]20,21 The in situ delivery of cytokine genes such as IL-12 that can promote Th1-mediated tumor cell cytotoxicity takes advantage of viable tumor cells at the site of treatment for maximal generation of tumor-associated antigens. Since peptides derived from the treated prostate cancer act as a vaccine, this approach can be termed in situ adenoviral vector-mediated gene-modified active vaccination.…”

“…[18][19][20] The construction and purification of the adenoviral vectors AdIl-12, AdIL-12/ B7 and Adbgal have been described. [16][17][18][19]21 Mice Male 129/Sv mice were used at 12-16 weeks of age. All mice were maintained in facilities approved by the American Association for Accreditation of Laboratory Animal Care, and all animal studies were conducted in accordance with the principles and procedures outlined in the NIH's Guide for the Care and Use of Laboratory Animals.…”