The Targeted Immunocytokine L19-IL2 Efficiently Inhibits the Growth of Orthotopic Pancreatic Cancer

Abstract

Purpose: Effective control of pancreatic cancer has been hampered primarily by the lack of tumor specificity of current treatment modalities. The highly specific antibody-mediated delivery of therapeutic agents to the tumor microenvironment might overcome this problem. We therefore investigated the therapeutic efficacy of the targeted immunocytokine L19-Interleukin-2 (L19-IL2), consisting of the human single-chain Fv antibody L19, which is highly specific for the extradomain B (ED-B) of fibronectin, and the human cytokine IL-2, in pancreatic cancer. Experimental Design: Therapeutic effects of L19-IL-2, IL-2, and gemcitabine on tumor growth and metastasis were evaluated in orthotopic mouse models for pancreatic cancer. Immunohistochemistry was done to define ED-B expression, tumor necrosis, apoptosis, proliferation, and invasion of macrophages and natural killer (NK) cells. NK cells were depleted by i.v. injection of an anti-asialo-GM-1antibody. Results: ED-B is selectively expressed in human pancreatic cancer and in primary tumors and metastases of the mouse models. L19-IL-2 therapy was clearly superior to untargeted IL-2 or gemcitabine and inhibited tumor growth and metastasis with remarkable long-term tumor control. Therapeutic effects were associated with the induction of extensive tumor necrosis and inhibition of tumor cell proliferation. Immunohistochemistry revealed an increase of macrophages and NK cells in the tumor tissue, suggesting immune-mediated mechanisms. The functional relevance of NK cells for the therapeutic effect of the targeted immunocytokine L19-IL-2 was confirmed by NK cell depletion, which completely abolished its antitumor efficacy. Conclusions: These preclinical results strongly encourage the initiation of clinical studies using L19-IL-2 in pancreatic cancer.

Radiotherapy Combined with the Immunocytokine L19-IL2 Provides Long-lasting Antitumor Effects

“…For the models presented in this study, no additional benefit was observed for the use of the single treatment with L19-IL2 in comparison with IL2 treatment. This is in contradiction with the results from previous studies, showing that L19-IL2 provides a stronger antitumor effect compared with equimolar dosing of untargeted IL2 in an F9 teratocarcinoma or a human pancreatic carcinoma xenograft model (16,42). This might be explained by the use of different mouse strains, tumor models, and treatment schedules.…”

Antitumor effects of EMAP II against pancreatic cancer through inhibition of fibronectin-dependent proliferation

“…Although this model may represent a somewhat different tumor microenvironment and likely lacks similar metastatic pathways compared to an orthotopic model, it does provide accurate monitoring and measurement of tumor size within an angiogenesis-dependent tumor progression scenario that functionally combines xenografted tumor cells with host stroma. Excessive FN expression has been reported in human pancreatic cancers as well as in the tumor microenvironment of subcutaneous and orthotopic experimental pancreatic cancer models, 13,14,29 indicating the possibly important implications of the observed EMAP II effect on FN-induced tumor progression.…”

“…A recent study demonstrated the effectiveness of an immunocytokine targeting the extradomain B of FN for inhibition of experimental pancreatic cancer, in part dependent on the selective expression of this FN domain in malignant tissues. 29 We observed that EMAP II treatment caused an obvious decrease in expression of both host and tumor Acarregui (University of Iowa, Iowa City, IA) and were grown on Type I Collagen (BD Biosciences, Bedford, MA) coated plates in E-Stim media supplemented with epidermal growth factor and endothelial cell growth supplement (BD Biosciences) at 37°C in a humidified 5% CO 2 atmosphere.…”

A Chemically Defined Trifunctional Antibody–Cytokine–Drug Conjugate with Potent Antitumor Activity

“…Antibodydrug conjugates (ADC) are armed versions of monoclonal antibodies, which may deliver a highly potent cytotoxic agent at the tumor site, thus helping spare normal tissues (19,20). Similarly, a large number of proinflammatory cytokines have been genetically fused to tumor-targeting recombinant antibodies, yielding fusion proteins (termed "immunocytokines") which display a potent therapeutic activity in mouse models of the disease and encouraging results in patients with cancer (6,7,9,11,14,15,(21)(22)(23)(24)(25)(26)(27).…”