Discovery of a Linear Peptide for Improving Tumor Targeting of Gene Products and Treatment of Distal Tumors by IL-12 Gene Therapy

Abstract

Like many effective therapeutics, interleukin-12 (IL-12) therapy often causes side effects. Tumor targeted delivery may improve the efficacy and decrease the toxicity of systemic IL-12 treatments. In this study, a novel targeting approach was investigated. A secreted alkaline phosphatase (SEAP) reporter gene-based screening process was used to identify a mini-peptide which can be produced in vivo to target gene products to tumors. The coding region for the best peptide was inserted into an IL-12 gene to determine the antitumor efficacy. Affinity chromatography, mass spectrometry analysis, and binding studies were used to identify a receptor for this peptide. We discovered that the linear peptide VNTANST increased the tumor accumulation of the reporter gene products in five independent tumor models including one human xenogeneic model. The product from VNTANST-IL-12 fusion gene therapy increased accumulation of IL-12 in the tumor environment, and in three tumor models, VNTANST-IL-12 gene therapy inhibited distal tumor growth. In a spontaneous lung metastasis model, inhibition of metastatic tumor growth was improved compared to wild-type IL-12 gene therapy, and in a squamous cell carcinoma model, toxic liver lesions were reduced. The receptor for VNTANST was identified as vimentin. These results show the promise of using VNTANST to improve IL-12 treatments.

Safety and Efficacy of Tumor-Targeted Interleukin 12 Gene Therapy in Treated and Non-Treated, Metastatic Lesions

“…The electroporation itself did not cause any severe adverse events similar to multiple published reports [3, 12, 17, 24]. This ttIL12 pDNA strategy did not cause any severe adverse events, and there were no increases in the severity of measured metabolic or hematologic metrics compared to baseline levels.…”

“…The IL-12 cytokine shares close homology among several species including mice, monkeys, humans, and canines [12], and human IL12 has been shown to be biologically active in canines [18]. The VNTANST tumor-targeting sequence remained the same as vimentin, like IL12, is highly conserved among species [19].…”

“…However, genetic delivery methods have not yet been discovered; therefore, the same hurdles which inhibit all protein therapeutics preclude the feasibility of immunocytokines [11]. Alternatively, tumor-targeting peptides can easily be encoded into therapeutic plasmid DNA (pDNA), and the gene product can both home to distant tumors and deploy the immune-stimulating payload [12–14]. The peptide-cytokine VNTANST-IL12 can successfully perform these roles by targeting ectopically expressed cell-surface vimentin and utilizing the pleiotropic, antitumor cytokine IL12 [12, 15, 16].…”

“…Treatment with electroporation-mediated VNTANST-IL12 (ttIL12) pDNA can inhibit primary and metastatic tumor growth and development and extend survival in several syngeneic, murine models of cancer while simultaneously improving safety compared to wildtype (wt) IL12 pDNA treatments [12, 15, 17]. These results mandate further investigation, and the next step towards entering the clinical arena is determining the safety and tolerability at clinically-relevant dose levels.…”

Molecular mechanisms of oncogene-induced inflammation and inflammation-sustained oncogene activation in gastrointestinal tumors: An underappreciated symbiotic relationship

“…Pancreatitis increases patients’ chances of developing PDAC by 16-fold (70). However, PDAC patients do not have pancreatitis, which makes the link between these two diseases confusing.…”