Biological evaluation of both enantiomers of fluoro-thalidomide using human myeloma cell line H929 and others

<div><p>Over the last few years, thalidomide has become one of the most important anti-tumour drugs for the treatment of relapsed-refractory multiple myeloma. However, besides its undesirable teratogenic side effect, its configurational instability critically limits any further therapeutic improvements of this drug. In 1999, we developed fluoro-thalidomide which is a bioisostere of thalidomide, but, in sharp contrast to the latter, it is configurationally stable and readily available in both enantiomeric forms. The biological activity of fluoro-thalidomide however, still remains virtually unstudied, with the exception that fluoro-thalidomide is not teratogenic. Herein, we report the first biological evaluation of fluoro-thalidomide in racemic and in both (<i>R</i>)- and (<i>S</i>)-enantiomerically pure forms against (<i>in vitro</i>) H929 cells of multiple myeloma (MM) using an annexin V assay. We demonstrate that all fluoro-thalidomides inhibited the growth of H929 MM cells without any <i>in-vivo</i> activation. Furthermore, we report that the enantiomeric forms of fluoro-thalidomide display different anti-tumour activities, with the (<i>S</i>)-enantiomer being noticeably more potent. The angiogenesis of fluoro-thalidomides is also investigated and compared to thalidomide. The data obtained in this study paves the way towards novel pharmaceutical research on fluoro-thalidomides.</p></div