The CIGB-370 recombinant polypeptide is antiangiogenic and antimetastatic in vitro and antiproliferative in vivo in xenograft mouse models with human tumor cells. The antibody response of this bacterial biomolecule can cause inmunoenadverse reactions and alters the effectiveness of the drug during its study in humans. The validation of two tiered heterogeneous immunoassays with CIGB-370 coated directly on the solid phase and revealed with protein A-peroxidase was performed. One was a screening immunoassay and the other was a competitive immunoassay confirming of specificity. With these immunoassays, plasma samples were evaluated. These samples were extracted in a retrospective clinical trial of 18 cancer patients who received an infusion of three doses of CIGB-370 (1.8, 3.7, and 6.1 mg/m2) intravenously over 1 hour, twice in a week for 4 weeks. The calculated screening and confirmation cut-point were floating. These immunoassays detected antibodies to CIGB-370 and not to other contaminants of process or product or of human plasma. The intra- and inter-assay coefficients of variation of the immunoassays were less than 20%. The sensitivity of these immunoassays allowed for the detection of a prevalence of anti CIGB-370 antibodies higher than 82%. The prevalence of patients with induced antibodies was significantly higher than that of patients with pre-existing anti-CIGB-370 antibodies. This tiered immunoassay methodology with adequate specificity, sensitivity, selectivity and precision allows for the detection of anti-CIGB-370 antibodies in cancer patients treated with CIGB-370 with or without structural modifications in an initial clinical trial and makes it possible to study clinical relevance of these antibodies.
