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Nonviral interferon alpha gene therapy inhibits growth of established tumors by eliciting a systemic immune response
Abstract:
A plasmid expression system encoding murine IFN-alpha4 and complexed with a protective interactive noncondensing polymeric (PINC) delivery system was used for in vivo immunotherapy treatment of an immunogenic murine renal cell carcinoma, Renca, and a nonimmunogenic mammary adenocarcinoma, TS/A. Mice bearing established tumors were treated with IFN-alpha/polyvinylpyrrolidone (PVP) expression complexes via direct intratumoral injection. Up to 100% inhibition of tumor growth was observed in the treated mice. By using an optimal dose of 96 and 48 microg of formulated IFN-alpha plasmid for the treatment of Renca and TS/A, respectively, 30% (Renca) and 10% (TS/A) of the treated animals remained tumor free. Inhibition of tumor growth was dependent on activation of the immune system. The antitumor activity elicited by IFN-alpha gene therapy was abrogated when mice were selectively depleted of CD8+ T cells. By contrast, depletion of CD4+ T cells resulted in enhanced tumor rejection following IFN-alpha/PVP treatments. Finally, mice that remained tumor free following IFN-alpha gene therapy displayed immune resistance to a subsequent tumor challenge. These data provide evidence that IFN-alpha gene therapy can be used to induce an efficient antitumor response in vivo.
Insights
This study shows that interferon-alpha (IFN-alpha) gene therapy, delivered via a PINC system, effectively inhibited tumor growth in mice. This immunotherapy activated the immune system, leading to long-term tumor resistance in some animals.
Area of Science:
- * Immunotherapy and Gene Therapy
- * Oncology and Tumor Immunology
Background:
- * Established tumors, including renal cell carcinoma (Renca) and mammary adenocarcinoma (TS/A), were targeted for treatment.
- * A plasmid expression system encoding murine interferon-alpha4 (IFN-alpha4) was utilized.
- * The IFN-alpha4 plasmid was complexed with a protective interactive noncondensing polymeric (PINC) delivery system for enhanced stability and efficacy.
Purpose of the Study:
- * To evaluate the in vivo efficacy of IFN-alpha gene therapy using a PINC delivery system against murine tumors.
- * To investigate the immunological mechanisms underlying the observed antitumor responses.
- * To assess the development of immune memory following successful treatment.
Main Methods:
- * Mice with established Renca and TS/A tumors received intratumoral injections of IFN-alpha/polyvinylpyrrolidone (PVP) expression complexes.
- * Dose-optimization studies were conducted using 96 microg for Renca and 48 microg for TS/A.
- * Immune cell depletion studies (CD8+ and CD4+ T cells) were performed to elucidate the immune response pathways.
Main Results:
- * IFN-alpha/PVP treatment resulted in up to 100% inhibition of tumor growth.
- * Complete tumor eradication was achieved in 30% of Renca-treated and 10% of TS/A-treated mice.
- * Antitumor activity was dependent on CD8+ T cells, while CD4+ T cell depletion enhanced tumor rejection.
Conclusions:
- * IFN-alpha gene therapy, delivered via PINC, is a potent strategy for inducing in vivo antitumor immunity.
- * The therapy establishes immune memory, conferring resistance to subsequent tumor challenges.
- * This approach holds promise for developing effective cancer immunotherapies.