Elevated Serum Megakaryocyte Potentiating Factor as a Predictor of Poor Survival in Patients with Mesothelioma and Primary Lung Cancer

Background: There is an urgent need for a companion assay to work with mesothelin-targeted therapeutic agents and for noninvasive and accurate prognostication of malignant mesothelioma (MM) patients. We report the development and validation of a blood-based assay for megakaryocyte potentiating factor (MPF) and the evaluation of its effectiveness for prognosis in MM and lung cancer patients. Methods: Using electrochemiluminescence technology, we developed a sensitive MPF assay and performed both analytical and clinical validations. Further, the effectiveness of the MPF assay in predicting prognosis was evaluated for 95 MM and 272 lung cancer patients. Results: We performed comprehensive analytical and clinical validation, including precision and accuracy, interference, preanalytical variables, sensitivity, and specificity for mesothelioma. In MM patients, increased serum MPF is a predictor of poor survival with a hazard ratio (HR) = 2.46 (log-rank P = 0.003; n = 95). In refractory MM patients, increased MPF is a strong predictor of poor outcome with an HR = 6.12 (log-rank P = 0.0007; n = 57). In a lung cancer patient cohort, increased MPF is a predictor of poor survival, with an HR = 1.57 (log-rank P = 0.003; n = 272). Conclusions: The MPF assay has robust technical characteristics, with strong analytic and clinical validation. Clinical studies indicate that increased serum MPF is a predictor of poor survival for MM patients, throughout the course of the disease. Increased MPF is also associated with poor overall survival for patients with newly diagnosed lung cancer.