Immunohistochemical evaluation of epithelial ovarian carcinomas identifies three different expression patterns of the MX35 antigen, NaPi2b

• Background: To characterize the expression of the membrane transporter NaPi2b and antigen targeted by the MX35 antibody in ovarian tumor samples. The current interest to develop monoclonal antibody based therapy of ovarian cancer by targeting NaPi2b emphasizes the need for detailed knowledge and characterization of the expression pattern of this protein. For the majority of patients with ovarian carcinoma the risk of being diagnosed in late stages with extensive loco-regional spread disease is substantial, which stresses the need to develop improved therapeutic agents. Methods: The gene and protein expression of SLC34A2/NaPi2b were analyzed in ovarian carcinoma tissues by QPCR (n = 73) and immunohistochemistry (n = 136). The expression levels and antigen localization were established and compared to the tumor characteristics and clinical data. Results: Positive staining for the target protein, NaPi2b was detected for 93% of the malignant samples, and we identified three separate distribution patterns of the antigen within the tumors, based on the localization of NaPi2b. There were differences in the staining intensity as well as the distribution pattern when comparing the tumor grade and histology, the mucinous tumors presented a significantly lower expression of both the targeted protein and its related gene. Conclusion: Our study identified differences regarding the level of the antigen expression between tumor grade and histology. We have identified differences in the antigen localization between borderline tumors, type 1 and type 2 tumors, and suggest that a pathological evaluation of NaPi2b in the tumors would be helpful in order to know which patients that would benefit from this targeted therapy.

Ämnesord

MEDICIN OCH HÄLSOVETENSKAP  -- Klinisk medicin -- Cancer och onkologi (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Clinical Medicine -- Cancer and Oncology (hsv//eng)

MEDICIN OCH HÄLSOVETENSKAP  -- Klinisk medicin -- Reproduktionsmedicin och gynekologi (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Clinical Medicine -- Obstetrics, Gynaecology and Reproductive Medicine (hsv//eng)

Nyckelord

Ovarian cancer

NaPi2b expression

Monoclonal antibody

Radiotherapy

monoclonal-antibody mx35

alpha-radioimmunotherapy

cancer patients

drug conjugate

dosimetry

localization

slc34a2

pb-212-tcmc-trastuzumab

pharmacokinetics

micrometastases

Oncology

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