Interferon-beta gene therapy inhibits tumor formation and causes regression of established tumors in immune-deficient mice

Abstract

Despite the potential of type 1 interferons (IFNs) for the treatment of cancer, clinical experience with IFN protein therapy of solid tumors has been disappointing. IFN-beta has potent antiproliferative activity against most human tumor cells in vitro in addition to its known immunomodulatory activities. The antiproliferative effect, however, relies on IFN-beta concentrations that cannot be achieved by parenteral protein administration because of rapid protein clearance and systemic toxicities. We demonstrate here that ex vivo IFN-beta gene transduction by a replication-defective adenovirus in as few as 1% of implanted cells blocked tumor formation. Direct in vivo IFN-beta gene delivery into established tumors generated high local concentrations of IFN-beta, inhibited tumor growth, and in many cases caused complete tumor regression. Because the mice were immune-deficient, it is likely that the anti-tumor effect was primarily through direct inhibition of tumor cell proliferation and survival. Based on these studies, we argue that local IFN-beta gene therapy with replication-defective adenoviral vectors might be an effective treatment for some solid tumors.

Figure 1

(A) Either uninfected MDA-MB-468 cells (○) or cells infected with H5.110hIFNβ at 0.01% (▵), 0.03% (□), 0.1% (▿), or 0.3% (•) were injected s.c. into the flanks of nude mice, and mean tumor size was plotted versus time after tumor cell implantation. (B) Kaplan-Meier plot showing the percentage survival of mice over the observation period of 109 days. Uninfected cells (○) or H5.110hIFNβ-infected cells at 0.01% (▵), 0.03% (□), 0.1% (▿), or 0.3% (•).

Figure 2

(A) Ex vivo IFN-β gene therapy in KM12L4A cells (a), Huh7 cells (b), and ME180 cells (c). Mean tumor size was plotted versus time after tumor cell implantation. Mice were implanted with uninfected cells (■) or H5.110hIFNβ-infected cells at 1% (•) or 10% (▴). In those groups in which some mice were sacrificed, the tumor size is presented as the average with last value carried forward for the sacrificed animals. Discontinuation of plots reflects the death or sacrifice of all animals in a group. (B) Percentage survival of mice over the observation period of 70 days. a–c show the data generated with mice implanted with KM12L4A cells, Huh7 cells, and ME180 cells, respectively. Uninfected cells (■) or H5.110hIFNβ-infected cells at 1% (•) and 10% (▴).

Figure 3

Direct in vivo treatment of established MDA-MB-468 tumors. Tumors were injected with H5.110hIFNβ at 3 × 10⁹ pfu (•), 1 × 10⁹ pfu (■), 3 × 10⁸ pfu (○), 1 × 10⁸ pfu (▵), and 3 × 10⁷ pfu (▿), respectively, or with PBS (□), or with H5.110lacZ at 3 × 10⁹ pfu (⊠), 1 × 10⁹ pfu (◊), 3 × 10⁸ pfu (▴), and 1 × 10⁸ pfu (▹), respectively. Tumor sizes were measured over 14 days after the treatment injections.

Figure 4

(A) Established MDA-MB-468 tumors were injected with H5.110lacZ (Upper) or H5.110hIFNβ (Lower) at 1 × 10⁹ pfu per mouse, and tumors were harvested 4 days later. Histological analysis then was performed; hematoxylin/eosin-stained sections are shown. More apoptotic cells (indicated by the arrows) were noted in the H5.110hIFNβ-injected tumor. (B) Confirmation of apoptosis by 4′,6-diamidino-2-phenylindole staining (a and c) or direct fluorescence detection of end-labeled and fragmented genomic DNA (b and d) in tumors treated either with H5.110lacZ (a and b) or H5.110hIFNβ (c and d).