Introduction:

The Cuban vaccine CIMAvax-EGF® is useful in non-small cell lung cancer (NSCLC) patients with high serum concentrations of epidermal growth factor ([EGF]), the current predictor of response. However, the discrimination between healthy individuals and NSCLC patients by [EGF], which determines the diagnostic accuracy and efficacy of the biomarker, is questionable. The controversy occurs mainly due to methodological deficiencies in its estimation.

Methods:

This work presents a new methodology for the quantification of human serum EGF, aimed at controlling the factors causing bias and variability in the estimates. The approach includes the development of the quantification kit UMELISA EGF®, the standardization of sera separation, and the normalization of [sEGF] regarding platelets count, as well as its interpretation.

Results:

The study revealed that patients and controls differ only by circulating EGF, measured in sera separated 1h after phlebotomy ([EGF]1h) and not by the total EGF in platelets, estimated in sera collected 4h after blood draw ([EGF]4h). Several variables related to EGF, with discriminatory power (diagnostic value) and potentiality as a biomarker, were identified. Specially circulating ([EGF]1h) and platelet-retained EGF ([EGF]4h-[EGF]1h), both normalized by platelets count, discriminate better patients from healthy controls than circulating or total EGF. Conclusions, the greater discriminatory capacity of the normalized variables indicates their more direct relationship with the biology of the tumor, compared to the current efficacy biomarker; as well as its better performance in predicting the response to anti-EGF/EGFR therapies and to the CIMAvax-EGF® in particular; which, together with the safety and low cost of the UMELISA EGF® test, suggests its possible use in the screening and early diagnosis of the disease in populations at risk.

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