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. 2011 Jul;122(1):171-7.
doi: 10.1016/j.ygyno.2011.03.002. Epub 2011 Mar 30.

High-grade, chemotherapy-resistant primary ovarian carcinoma cell lines overexpress human trophoblast cell-surface marker (Trop-2) and are highly sensitive to immunotherapy with hRS7, a humanized monoclonal anti-Trop-2 antibody

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High-grade, chemotherapy-resistant primary ovarian carcinoma cell lines overexpress human trophoblast cell-surface marker (Trop-2) and are highly sensitive to immunotherapy with hRS7, a humanized monoclonal anti-Trop-2 antibody

Joyce Varughese et al. Gynecol Oncol. 2011 Jul.

Abstract

Objective: We evaluated the expression of human trophoblast cell-surface marker (Trop-2) and the potential of hRS7, a humanized monoclonal anti-Trop-2 antibody, as a therapeutic agent against chemotherapy-resistant ovarian disease.

Methods: Trop-2 expression was evaluated by immunohistochemistry (IHC) in 50 ovarian serous papillary carcinoma specimens. Trop-2 expression was also evaluated by real-time PCR (qRT-PCR) and flow cytometry in a total of 6 primary ovarian cancer cell lines derived from patients with chemotherapy-resistant disease. Sensitivity to hRS7 antibody-dependent cellular cytotoxicity (ADCC) was tested in standard 5-hour ⁵¹Cr-release assays. The effect of serum and interleukin-2 (IL-2) on hRS7-mediated ADCC was also studied.

Results: Trop-2 expression was found in 41 of 50 (82%) tumor tissues tested by IHC. 83% (5 of 6) of the ovarian cancer cell lines tested by qRT-PCR and flow cytometry demonstrated high Trop-2 expression. All primary ovarian cancer cell lines expressing Trop-2 were highly sensitive to hRS7-mediated ADCC in vitro (range of killing: 19.3% to 40.8%) (p<0.001). Negligible cytotoxicity against chemotherapy-resistant ovarian cancers was seen in the absence of hRS7 or in the presence of rituximab control antibody (range of killing: 1.1% to 8.9%). Human serum did not significantly inhibit hRS7-mediated cytotoxicity while incubation with IL-2 in addition to hRS7 further increased the cytotoxic activity (p=0.04).

Conclusions: Trop-2 is highly expressed in chemotherapy-resistant ovarian cancer cell lines at mRNA and protein levels. Primary ovarian carcinoma cell lines are highly sensitive to hRS7-mediated cytotoxicity in vitro. hRS7 may represent a novel therapeutic agent for the treatment of high-grade, chemotherapy-resistant ovarian cancer.

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Figures

Figure 1
Figure 1
Representative immunohistochemical staining for Trop-2. A) normal ovarian tissue (0/1+ staining, magnification 20×), B) ovarian cancer (1+ staining, magnification 20×), C) ovarian cancer (2+ staining, magnification 20×), D) ovarian cancer (3+ staining, magnification 20×).
Figure 2
Figure 2
Representative cytotoxicity experiments using hRS7 against CC-ARK-1 (top panel), OSPC-ARK-4 (middle panel), and OSPC-ARK-3 (bottom panel) cell lines. High levels of hRS7-induced cytotoxicity were evident against CC-ARK-1 and OSPC-ARK-4 (top and middle panels) with effectors to target ratios of both 25:1 and 50:1. In contrast, decreased cytotoxicity was noted in OSPC-ARK-3 (bottom panel) consistent with decreased levels of Trop-2 expression by qRT-PCR and flow cytometry. In all cell lines tested, no significant cytotoxicity was detected in the absence of hRS7 or in the presence of rituximab control MAb.
Figure 3
Figure 3
Collective data representing effect of low doses of interleukin-2 (IL-2) in combination with hRS7 on ADCC on primary ovarian cancer cell lines (top panel). hRS7-mediated ADCC was significantly increased in the presence of low doses of IL-2. No significant increase in cytotoxicity was detected after 5 hours of IL-2 treatment in the absence of hRS7 or in the presence of rituximab control MAb. Representative cytotoxicity experiments adding human serum to hRS7 against CC-ARK-1 (middle panel) and CC-ARK-2 (bottom panel). Addition of physiological concentrations of IgG (i.e., heat-inactivated serum diluted 1:2) to PBL in the presence of hRS7 did not significantly decrease the degree of ADCC. The addition of untreated serum to PBL in the presence of hRS7 significantly increased hRS7-mediated ADCC in CC-ARK-2 (bottom panel) suggesting a peculiar sensitivity of this cell line to complement-dependent cytotoxicity.

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References

    1. Jemal A, Siegel R, Xu J, Ward E. Cancer statistics, 2010. CA Cancer J Clin. 2010;60:277–300. - PubMed
    1. Cho KR, Shih I. Ovarian cancer. Annu Rev Pathol. 2009;4:287–313. - PMC - PubMed
    1. Martin LP, Schilder RJ. Management of recurrent ovarian carcinoma: current status and future directions. Semin Oncol. 2009;36:112–125. - PubMed
    1. Lipinski M, Parks DR, Rouse RV, Herzenberg LA. Human trophoblast cell-surface antigens defined by monoclonal antibodies. Proc Natl Acad Sci USA. 1981;78:5147–5150. - PMC - PubMed
    1. Miotti S, Canevari S, Menard S, Mezzanzanica D, Porro G, Pupa SM, et al. Characterization of human ovarian carcinoma-associated antigens defined by novel monoclonal antibodies with tumor-restricted specificity. Int J Cancer. 1987;39:297–303. - PubMed

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