Intrauterine enzyme replacement therapies for lysosomal storage disorders: Current developments and promising future prospects

Lysosomal storage disorders (LSDs) are a group of monogenic condition, with many characterized by an enzyme deficiency leading to the accumulation of an undegraded substrate within the lysosomes. For those LSDs, postnatal enzyme replacement therapy (ERT) represents the standard of care, but this treatment has limitations when administered only postnatally because, at that point, prenatal disease sequelae may be irreversible. Furthermore, most forms of ERT, specifically those administered systemically, are currently unable to access certain tissues, such as the central nervous system (CNS), and furthermore, may initiate an immune response. In utero enzyme replacement therapy (IUERT) is a novel approach to address these challenges evaluated in a first-in-human clinical trial for IUERT in LSDs (NCT04532047). IUERT has numerous advantages: in-utero intervention may prevent early pathology; the CNS can be accessed before the blood-brain barrier forms; and the unique fetal immune system enables exposure to new proteins with the potential to prevent an immune response and may induce sustained tolerance. However, there are challenges and limitations for any fetal procedure that involves two patients. This article reviews the current state of IUERT for LSDs, including its advantages, limitations, and potential future directions for definitive therapies.

Prenatal Somatic Cell Gene Therapies: Charting a Path Toward Clinical Applications (Proceedings of the CERSI-FDA Meeting)

We are living in a golden age of medicine in which the availability of prenatal diagnosis, fetal therapy, and gene therapy/editing make it theoretically possible to repair almost any defect in the genetic code. Furthermore, the ability to diagnose genetic disorders before birth and the presence of established surgical techniques enable these therapies to be delivered safely to the fetus. Prenatal therapies are generally used in the second or early third trimester for severe, life-threatening disorders for which there is a clear rationale for intervening before birth. While there has been promising work for prenatal gene therapy in preclinical models, the path to a clinical prenatal gene therapy approach is complex. We recently held a conference with the University of California, San Francisco-Stanford Center of Excellence in Regulatory Science and Innovation, researchers, patient advocates, regulatory (members of the Food and Drug Administration), and other stakeholders to review the scientific background and rationale for prenatal somatic cell gene therapy for severe monogenic diseases and initiate a dialogue toward a safe regulatory path for phase 1 clinical trials. This review represents a summary of the considerations and discussions from these conversations.

The impact of a short cervix and funneling on the outcome in singleton pregnancies treated with an Arabin-pessary or a McDonald cerclage

OBJECTIVE

The presence of sonographic funneling is a co-predictor of spontaneous preterm birth (sPTB). The aim of this study was to assess the outcome in patients with a short cervix and funneling after a McDonald cerclage or an Arabin pessary.

METHODS

We retrospectively analyzed data of 238 singleton pregnancies with cervical shortening <25 mm subclassified by either isolated cervical shortening (n = 105) or cervical shortening and additional funneling (n = 133). In the group of isolated cervical shortening, a total of 93 patients had received a cervical pessary and 12 had McDonald cerclage. In the group of patients with additional funneling, 98 had received a cervical pessary and 35 had a cerclage. We evaluated PTB rates <28, <32, <34, and <37 weeks as well as prolongation of gestation, birth weight, and admission to NICU.

RESULTS

In the pessary groups (n = 191), funneling resulted in a significantly higher rate of PTB before 34 weeks as compared to patients with isolated cervical shortening (26.5 versus 8.6%, p=.0066). Similarly, in the cerclage groups (n = 47), funneling resulted in an absolute increase of PTB, albeit not significant (37.1 versus 0%, p=.1435) due to the smaller number. There were no significant differences in terms of prevention of PTB before 34 weeks in patients treated with pessary or cerclage, neither in the group of patients with isolated shortening nor in the group of patients with additional funneling (p=.9771 and p=.3916, respectively). However, in patients with funneling, we demonstrated a significantly lower neonatal admission rate in the pessary arm (n = 27, 27.6%) as compared to the cerclage arm (n = 31, 88.6%) (p = .0002). Similarly, the NICU admission time was shorter in both pessary groups -with and without funneling - as compared to patients treated with cerclage (p = .0000).

CONCLUSION

Pessary placement and cerclage should optimally be considered before the presence of funneling. Furthermore, there were lower rates of neonatal admission during pregnancy and a shorter admission time of babies after birth when mothers received a cervical pessary as compared to the group with cervical cerclage.

Combined treatment of McDonald cerclage and Arabin-pessary: a chance in the prevention of spontaneous preterm birth?

Background: Patients with cervical shortening obtained by transvaginal ultrasound and/or previous preterm delivery are at increased risk for preterm birth in the current pregnancy. The aim of the present cohort study was to compare the rate of preterm birth and early neonatal parameters in patients at risk and screening patients who received either a cerclage or a combined treatment of cerclage and cervical pessary.Methods: A retrospective cohort study was conducted from March 2005 to March 2017 including all patients in our department which received a McDonald cerclage or a combined treatment of McDonald cerclage and an Arabin pessary. A total of 81 women with singleton pregnancies were considered the final sample of this cohort study, of whom 34 patients received a cerclage and 47 patients received a cerclage combined with a pessary. Patients "at risk" with a history of preterm birth at <37 weeks of gestation, late-term abortion, conization, or cervical cerclage in a previous pregnancy because of a cervical shortening <10th percentile and women with no inherent historic risk factors but a current cervical length <3rd percentile (screening group) were analyzed separately. We defined delivery <34 weeks of gestation as the primary outcome. Secondary outcomes were preterm birth (PTB) <28, <32, and <37 weeks of gestation, admission to the neonatal intensive care unit (NICU), neonatal admission time, birthweight, and prolongation of the gestation.Results: There were no differences between the two study groups with regard to baseline characteristics. Delivery <34 weeks of gestation occurred in 32.4 and 27.7% of patients treated with cerclage versus combined treatment respectively (p = .48). Similarly, there was no difference in the rate of preterm birth at <28, <32, or <37 weeks of gestation. The mean neonatal admission time at the neonatal intensive care unit was shorter in the combined treatment group versus in the cerclage group (p = .02). There was a trend for higher birthweight (2368 g ± 962 vs. 2650 g ± 1063) in favor of the combined treatment arm (p = .077).Conclusion: The combined treatment of cerclage with an Arabin pessary seems to be a considerable alternative in the prevention of spontaneous PTB (sPTB), especially for patients with cervical length <3rd percentile, and in particular for patients with amnion prolapse in terms of birthweight and neonatal admission time.