Tacrolimus treatment in reproductive failures

Immunotherapy for repeated implantation failure (RIF) following in vitro fertilization (IVF), particularly treatment with the calcineurin inhibitor tacrolimus-has now been used for roughly a decade since its initial report. In that initial series, the clinical pregnancy rate was 64.0 %; however, acceptance was slow. A recent re-evaluation at our center yields a similarly high clinical pregnancy rate of 57.1 %. In our earlier cohort, 37.7 % of RIF cases showed Th1/Th2 cell ratio suggestive of immune-mediated rejection; a more recent survey found a comparable proportion (35.9 %), indicating that approximately one-third of RIF may involve an immune component. Tacrolimus has also shown promise in immunologically mediated recurrent pregnancy loss (RPL), and its potential indications may extend to preventing obstetric complications such as abruptio placentae, hypertensive disorders of pregnancy (HDP), and HELLP syndrome. We summarize our experience, situate it within the evolving literature, and outline priorities for confirmatory trials.