FOLR1 and neoplasm: It is noteworthy that both trials have been conducted using the anti-FRα murine monoclonal antibody MOv18 (see further discussion of this antibody below) and that in the OC/TR trial almost all the patients developed a HAMA response that precluded further treatment [134] and in the CAR trial an inhibitory factor developed in the serum of three of six patients tested over the period of treatment, which significantly reduced the ability of gene-modified T cells to respond against FRα positive tumor cells [133].