title: EphA2 immunoconjugate as molecularly targeted chemotherapy for ovarian carcinoma.
abstract: BACKGROUND
  EphA2 is overexpressed in many types of human cancer but is absent or expressed at low levels in normal epithelial tissues. We investigated whether a novel immunoconjugate containing an anti-EphA2 monoclonal antibody (1C1) linked to a chemotherapeutic agent (monomethyl auristatin phenylalanine [MMAF]) through a noncleavable linker maleimidocaproyl (mc) had antitumor activity against ovarian cancer cell lines and tumor models.
  
  
  METHODS
  Specificity of 1C1-mcMMAF was examined in EphA2-positive HeyA8 and EphA2-negative SKMel28 ovarian cancer cells by antibody binding and internalization assays. Controls were phosphate-buffered saline (PBS), 1C1, or control IgG-mcMMAF. Viability and apoptosis were investigated in ovarian cancer cell lines and tumor models (10 mice per group). Antitumor activities were tested in the HeyA8-luc and SKOV3ip1 orthotopic mouse models of ovarian cancer. Endothelial cells were identified by use of immunohistochemistry and anti-CD31 antibodies. All statistical tests were two-sided.
  
  
  RESULTS
  The 1C1-mcMMAF immunoconjugate specifically bound to EphA2-positive HeyA8 cells but not to EphA2-negative cells and was internalized by HeyA8 cells. Treatment with 1C1-mcMMAF decreased the viability of HeyA8-luc cells in an EphA2-specific manner. In orthotopic mouse models, treatment with 1C1-mcMMAF inhibited tumor growth by 85%-98% compared with that in control mice (eg, for weight of HeyA8 tumors, 1C1-mcMMAF = 0.05 g and control = 1.03 g; difference = 0.98 g, 95% confidence interval [CI] = 0.40 to 1.58 g; P = .001). Even in bulkier disease models with HeyA8-luc cells, 1C1-mcMMAF treatment, compared with control treatment, caused regression of established tumors and increased survival of the mice (eg, 1C1-mcMMAF vs control, mean = 60.6 days vs 29.4 days; difference = 31.2 days, 95% CI = 27.6 to 31.2 days; P = .001). The antitumor effects of 1C1-mcMMAF therapy, in SKOV3ip1 tumors, for example, were statistically significantly related to decreased proliferation (eg, 1C1-mcMMAF vs control, mean = 44.1% vs 55.8% proliferating cells; difference = 11.7%, 95% CI = 2.45% to 20.9%; P = .01) and increased apoptosis of tumor cells (eg, 1C1-mcMMAF vs control, mean = 8.6% vs 0.9% apoptotic cells; difference = 7.7%, 95% CI = 3.8% to 11.7%; P < .001) and of mouse endothelial cells (eg, 1C1-mcMMAF vs control, mean 2.8% vs 0.4% apoptotic endothelial cells; difference = 2.4%, 95% CI = 1.4% to 4.6%; P = .034).
  
  
  CONCLUSIONS
  The 1C1-mcMMAF immunoconjugate had antitumor activity in preclinical models of ovarian carcinoma.
authors.affiliation: Department of Gynecologic Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA.
authors.forename: Jeong-Won
authors.initials: JW
authors.lastname: Lee
authors.forename: Hee Dong
authors.initials: HD
authors.lastname: Han
authors.forename: Mian M K
authors.initials: MM
authors.lastname: Shahzad
authors.forename: Seung Wook
authors.initials: SW
authors.lastname: Kim
authors.forename: Lingegowda S
authors.initials: LS
authors.lastname: Mangala
authors.forename: Alpa M
authors.initials: AM
authors.lastname: Nick
authors.forename: Chunhua
authors.initials: C
authors.lastname: Lu
authors.forename: Robert R
authors.initials: RR
authors.lastname: Langley
authors.forename: Rosemarie
authors.initials: R
authors.lastname: Schmandt
authors.forename: Hye-Sun
authors.initials: HS
authors.lastname: Kim
authors.forename: Shenlan
authors.initials: S
authors.lastname: Mao
authors.forename: John
authors.initials: J
authors.lastname: Gooya
authors.forename: Christine
authors.initials: C
authors.lastname: Fazenbaker
authors.forename: Dowdy
authors.initials: D
authors.lastname: Jackson
authors.forename: David A
authors.initials: DA
authors.lastname: Tice
authors.forename: Charles N
authors.initials: CN
authors.lastname: Landen
authors.forename: Robert L
authors.initials: RL
authors.lastname: Coleman
authors.forename: Anil K
authors.initials: AK
authors.lastname: Sood
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D000970:Antineoplastic Agents / Q000494:pharmacology* / Q000627:therapeutic use; D017209:Apoptosis / Q000187:drug effects; D015153:Blotting, Western; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D005260:Female; D005455:Fluorescent Antibody Technique; D006801:Humans; D018796:Immunoconjugates / Q000494:pharmacology* / Q000627:therapeutic use; D007150:Immunohistochemistry; D020287:In Situ Nick-End Labeling; D051379:Mice; D009842:Oligopeptides / Q000494:pharmacology* / Q000627:therapeutic use; D010051:Ovarian Neoplasms / Q000188:drug therapy* / Q000276:immunology*; D019408:Platelet Endothelial Cell Adhesion Molecule-1 / Q000032:analysis; D018809:Proliferating Cell Nuclear Antigen / Q000032:analysis; D036104:Receptor, EphA2 / Q000032:analysis / Q000037:antagonists & inhibitors* / Q000276:immunology; D023041:Xenograft Model Antitumor Assays
chemical_list: D000911:Antibodies, Monoclonal; D000970:Antineoplastic Agents; D018796:Immunoconjugates; D009842:Oligopeptides; D019408:Platelet Endothelial Cell Adhesion Molecule-1; D018809:Proliferating Cell Nuclear Antigen; D036104:Receptor, EphA2; C495575:monomethyl auristatin E