KAYOKO KIKUCHI

Introduction: Infertility is estimated to affect 8% to 12% of reproductive-aged couples worldwide. While approximately 85% of infertile couples have an identified cause, the remaining 15% suffer physically and emotionally from unexplained intractable infertility. In recent years, maternal-to-fetal immunological abnormalities have attracted attention as mechanisms that differ from the conventional factors contributing to infertility and pregnancy loss. A T-helper 2 (Th2)-dominant immune state has been proposed as a maternal immune alteration to eliminate rejection and induce tolerance to a semi-allogeneic fetus. An imbalance in Th1 responses would not induce adequate maternal immune tolerance to the fetus or early embryos. Tacrolimus, widely used as an immunosuppressant agent in solid organ transplant recipients, is expected to suppress maternal rejection and promote tolerance to early embryos after assisted reproductive technology by modulating the immunological environment of the preimplantation endometrium. We planned an exploratory clinical trial to determine the efficacy, safety, and dosage of tacrolimus in women with intractable infertility. Methods and analysis: This is a multicenter, 2-dose, single-group controlled trial in infertile women who failed to achieve a chemical pregnancy despite multiple in vitro fertilization (IVF) and embryo transfer (ET) treatment cycles. The following 2 key selection criteria were set: no underlying factors of infertility despite appropriate evaluation and presence of Th1-dominant immune state, defined as a Th1/Th2 cell ratio ≥ 10.3 in the peripheral blood. A total of 26 eligible participants are randomly assigned (in a 2:1 ratio) to receive immunosuppressive therapy with oral tacrolimus at a daily dose of 2 mg or 4 mg. Tacrolimus is administered for 16 days starting from 2 days before ET. The primary endpoint is the presence of clinical pregnancy 3 weeks after IVF/ET treatment, and the secondary endpoint is the presence of biochemical pregnancy 2 weeks after IVF/ET treatment. Safety evaluation and biomarker discovery for tacrolimus treatment in infertile women will be conducted simultaneously. Trial registration number: Japan Registry of Clinical Trials (jRCT; jRCTs031220235).

Introduction Patent ductus arteriosus (PDA) causes severe morbidity in premature infants. Although the use of indomethacin is the standard therapy for PDA, it is sometimes not applicable because of its adverse effects, such as renal and platelet dysfunctions. Paracetamol has emerged as an alternative to indomethacin owing to its excellent safety profile in infants. Of the recently reported case series and clinical trials on the use of paracetamol for PDA, there are few reports in Japan on paracetamol use in preterm infants. Furthermore, indications for the use of paracetamol for PDA have not been approved for use in PDA. While the safety of intravenous paracetamol therapy in case series of preterm infants treated for haemodynamically significant PDA (hsPDA) has been reported, studies which were conducted to compare paracetamol to indomethacin are limited. We, therefore, intend to investigate the hypothesis that intravenous administration of paracetamol has superior safety over indomethacin. Methods and analysis Multicentre open-label randomised controlled trial for intravenous administration of paracetamol for PDA in preterm infants. The inclusion criteria are (1) hsPDA, (2) gestational age from 24 to 34 weeks and birth weight (BW) from 500 to 2000 g, (3) enrolment between 24 hours and 7 days from birth and (4) obtaining parental consent. The primary outcome is renal dysfunction within 48 hours from the last dose of the study drug. Enrolled patients fulfilling all the inclusion criteria are randomly allocated to either intravenous paracetamol or intravenous indomethacin. This trial requires 110 patients. Ethics and dissemination The clinical trial would follow Japan’s Clinical Trials Act. The trial protocol was approved by the Clinical Research Review Board of Saitama Medical University (approval number: 222001). A written informed consent would be obtained from one of the parents. The results are expected to be published in a scientific journal. Trial registration number jRCTs031220386. Protocol version 31 March 2022, version 1.0.