MT95‐4, a fully humanized antibody raised against aminopeptidase N, reduces tumor progression in a mouse model

Abstract

Aminopeptidase N (APN/CD13) is involved in tumor cell invasion and tumor angiogenesis and is considered a promising therapeutic target in the treatment of cancer. To develop a novel monoclonal antibody-based cancer therapy targeting APN/CD13, we established a fully humanized anti-APN/CD13 monoclonal antibody, MT95-4. In vitro, MT95-4 inhibited APN/CD13 enzymatic activity on the tumor cell surface and blocked tumor cell invasion. B16 mouse melanoma cells stably expressing human APN/CD13 were also established and were inoculated s.c. or injected i.v. into nude mice. We found that expression of human APN/CD13 in murine melanoma cells increased the size of subcutaneous tumors, extent of lung metastasis and degree of angiogenesis in the subcutaneous tumors; these tumor-promoting and angiogenesis-promoting characteristics were reduced by the i.p. administration of MT95-4. To further verify the specificity of MT95-4 for neutralization of APN/CD13 activity, MT95-4 was administered into NOD/SCID mice inoculated s.c. with H1299 or PC14 cells, which exhibit high expression of APN/CD13, or with A549 cells, which exhibit weak expression of APN/CD13. MT95-4 reduced tumor growth and angiogenesis in mice bearing H1299-derived and PC14-derived tumors, but not in mice bearing A549-derived tumors. These results suggested that the antitumor and anti-angiogenic effects of MT95-4 were dependent on APN/CD13 expression in tumor cells. Given that MT95-4 is the first fully humanized monoclonal antibody against APN/CD13, MT95-4 should be recognized as a promising candidate for monoclonal antibody therapy against tumors expressing APN/CD13.

Allosteric inhibition of aminopeptidase N functions related to tumor growth and virus infection

“…Our results verify the critical role of APN dynamics in CoV infection and catalysis, and demonstrate that the open APN structure is inactive in peptide hydrolysis. Anti-APN antibodies that inhibit APN activity and reduce tumor growth 25,33 likely block ectodomain movements. The allosteric inhibition of APN functions shown here using viral proteins and drugs is likely to be due to suppression of APN transient conformational states, as shown for other enzymes 34 .…”

Aminopeptidase N/CD13 as a potential therapeutic target in malignant pleural mesothelioma

“…To examine the efficacy of APN/CD13 as a therapeutic target in MPM, we tested the antitumour effect of MT95-4, a fully humanised anti-APN/CD13 mAb established in our laboratory [25], in an orthotopic implantation mouse model of MPM, using MPM cells exhibiting high or low APN/CD13 expression. We found that MT95-4 administration suppressed tumour progression and angiogenesis only in tumours exhibiting high APN/CD13 expression.…”

“…MT-95-4 was developed in our laboratory as previously reported [25] and cisplatin was purchased from Nippon Kayaku (Tokyo, Japan). Male severe combined immunodeficient (SCID) mice (6 weeks old) were purchased from CLEA Japan (Osaka, Japan).…”

“…Quantitative real-time PCR RNA extraction, reverse transcription to cDNA and real-time quantitative PCR were performed as previously described [25]. The primers used were Hs00174265_m1 for APN/CD13, Hs00900055_m1 for vascular endothelial growth factor (VEGF) and 4352935E for β-actin (all from Applied Biosystems, Framingham, MA, USA).…”

Mesoporous Silica Nanocarriers with Cyclic Peptide Gatekeeper: Specific Targeting of Aminopeptidase N and Triggered Drug Release by Stimuli‐Responsive Conformational Transformation

“…H1299 and A549 cells have been shown to express high and low levels of APN, respectively . Similarly, we found that APN was overexpressed in H1299, but not in A549 cells (Figure S6).…”