Pfetin as a prognostic biomarker in gastrointestinal stromal tumor: novel monoclonal antibody and external validation study in multiple clinical facilities.

OBJECTIVE

The clinical course of gastrointestinal stromal tumor (GIST) spans a wide spectrum from a curable disorder to a highly malignant disease that leads to metastasis and death. To develop prognostic modalities for GIST patients, we developed a mouse monoclonal antibody against pfetin, the prognostic value of which has been previously reported.

METHODS

The reactivity of the monoclonal antibody against pfetin was examined by western blotting and immunohistochemistry.

RESULTS

Western blotting demonstrated that the monoclonal antibody was specific to pfetin. The immunohistochemical study demonstrated that the 5-year disease-free survival rate was 93.2% and 94.5% for GIST patients with pfetin-positive tumors and 70.0% and 80.7% for those with pfetin-negative tumors in the 159 cases from the National Cancer Center Hospital (P < 0.0001) and in the 100 cases from Niigata University Medical and Dental Hospital (P < 0.0001), respectively. Uni- and multivariate analyses revealed that pfetin expression was a powerful prognostic factor among the clinico-pathological parameters examined.

CONCLUSIONS

These results establish pfetin as a practical prognostic marker for GIST patients after surgery. Pfetin may also present a novel therapeutic target to prevent recurrence of GIST.