Embryotoxicity and maternal serum concentrations of medroxyprogesterone acetate (MPA) in baboons (Papio cynocephalus)

In an in-vitro model using human fetal membranes, 17-α hydroxyprogesterone caproate is not an optimal progestogen for inhibition of fetal membrane weakening

BACKGROUND

The progestogen 17-α hydroxyprogesterone caproate (17-OHPC) is 1 of only 2 agents recommended for clinical use in the prevention of spontaneous preterm delivery, and studies of its efficacy have been conflicting. We have developed an in-vitro model to study the fetal membrane weakening process that leads to rupture in preterm premature rupture of the fetal membranes (pPROM). Inflammation/infection associated with tumor necrosis factor-α (TNF-α) induction and decidual bleeding/abruption associated thrombin release are leading causes of preterm premature rupture of the fetal membranes. Both agents (TNF-α and thrombin) cause fetal membrane weakening in the model system. Furthermore, granulocyte-macrophage colony-stimulating factor (GM-CSF) is a critical intermediate for both TNF-α and thrombin-induced fetal membrane weakening. In a previous report, we demonstrated that 3 progestogens, progesterone, 17-alpha hydroxyprogesterone (17-OHP), and medroxyprogesterone acetate (MPA), each inhibit both TNF-α- and thrombin-induced fetal membrane weakening at 2 distinct points of the fetal membrane weakening pathway. Each block both the production of and the downstream action of the critical intermediate granulocyte-macrophage colony-stimulating factor.

OBJECTIVE

The objective of the study was to characterize the inhibitory effects of 17-OHPC on TNF-α- and thrombin-induced fetal membrane weakening in vitro.

STUDY DESIGN

Full-thickness human fetal membrane fragments from uncomplicated term repeat cesarean deliveries were mounted in 2.5 cm Transwell inserts and cultured with/without 17-alpha hydroxyprogesterone caproate (10^-9 to 10^-7 M). After 24 hours, medium (supernatant) was removed and replaced with/without the addition of tumor necrosis factor-alpha (20 ng/mL) or thrombin (10 U/mL) or granulocyte-macrophage colony-stimulating factor (200 ng/mL). After 48 hours of culture, medium from the maternal side compartment of the model was assayed for granulocyte-macrophage colony-stimulating factor and the fetal membrane fragments were rupture strength tested.

RESULTS

Tumor necrosis factor-alpha and thrombin both weakened fetal membranes (43% and 62%, respectively) and increased granulocyte-macrophage colony-stimulating factor levels (3.7- and 5.9-fold, respectively). Pretreatment with 17-alpha hydroxyprogesterone caproate inhibited both tumor necrosis factor-alpha- and thrombin-induced fetal membrane weakening and concomitantly inhibited the induced increase in granulocyte-macrophage colony-stimulating factor in a concentration-dependent manner. However, contrary to our prior reports regarding progesterone and other progestogens, 17-alpha hydroxyprogesterone caproate did not also inhibit granulocyte-macrophage colony-stimulating factor-induced fetal membrane weakening.

CONCLUSION

17-Alpha hydroxyprogesterone caproate blocks tumor necrosis factor-alpha- and thrombin-induced fetal membrane weakening by inhibiting the production of granulocyte-macrophage colony-stimulating factor. However, 17-alpha hydroxyprogesterone caproate did not also inhibit granulocyte-macrophage colony-stimulating factor-induced weakening. We speculate that progestogens other than 17-alpha hydroxyprogesterone caproate may be more efficacious in preventing preterm premature rupture of the fetal membranes-related spontaneous preterm birth.

Pre- and postnatal development in the cynomolgus monkey following administration of ABT-874, a human anti-IL-12/23p40 monoclonal antibody

BACKGROUND

ABT-874 is an anti-IL-12/23 monoclonal antibody that binds to the p40 subunit of human IL-12 and IL-23. As part of its preclinical safety assessment, studies were conducted to assess its potential effects on pre- and postnatal development in cynomolgus monkeys.

METHODS

In the embryo-fetal development studies, ABT-874 was administered once weekly subcutaneously to adult female cynomolgus monkeys at doses of 0, 5, 25, or 100 mg/kg during gestation days (GD) 20 to 48. Fetuses were examined for external, visceral, and skeletal development on GD 100 or 150. In the pre- and postnatal study, ABT-874 was administered once weekly subcutaneously to adult female cynomolgus monkeys at doses of 10, 50, or 200 mg/kg from GD 20 through postpartum day 182. Infants were examined from birth up to 9 months of age for morphological and functional development. Potential effects on the infant immune system were evaluated by immunophenotyping of peripheral blood lymphocytes and by T-dependent antibody response to KLH.

RESULTS

There was no ABT-874-related maternal toxicity or adverse effects on fetuses or infants. ABT-874 was present in maternal and fetal serum at GD 100 and 150, and in infant serum through day 63 postbirth. ABT-874 was also present at low levels in breast milk through postpartum day 175.

CONCLUSIONS

Exposure of cynomolgus monkey fetuses and infants to ABT-874 had no adverse effects on embryo-fetal or postnatal development.

Nongenital malformations following exposure to progestational drugs: The last chapter of an erroneous allegation

In the late 1960s and 1970s, a number of epidemiological studies were published indicating that pregnant women who were exposed to an array of sex steroids delivered infants with an increased incidence of nongenital congenital malformations. Because of these publications, the Food and Drug Administration (FDA), in conjunction with various pharmaceutical companies, labeled the therapeutic exposure of progestational drugs and contraceptives in pregnant women as a risk factor for limb-reduction defects (LRDs) and congenital heart defects (CHDs). Subsequently there was a rapid decrease in the exposure of pregnant women to these drugs and the initiation of numerous lawsuits alleging that a particular progestational drug was responsible for a child's nongenital congenital malformation. Wilson and Brent (1981) published an article indicating that epidemiological and animal studies of these drugs, and basic science did not support the package insert's warnings. Many new and previous animal and epidemiological studies did not support the FDA box warning. In 1987 the FDA held a hearing in which the FDA, the Teratology Society, the Centers for Disease Control and Prevention, the American College of Obstetrics and Gynecology, and other organizations supported the position that progestational agents did not result in nongenital malformations. An editorial appeared in Teratology congratulating the FDA for removing the warning label on oral contraceptives regarding nongenital malformations. In 1999 the FDA published new wording for package inserts that removed warnings for nongenital malformations for all progestational agents. In spite of the recent changes in the package inserts, lawsuits have alleged that progestational drugs cause nongenital malformations. It took 22 years from the time a box warning was required by the FDA until the warnings were removed in 1999. The 1999 FDA publication, which is a scholarly and objective document, should put an end to 2 decades of concern and anxiety for pregnant women or women of reproductive age. Could scientists, the pharmaceutical companies, or the FDA have prevented the mislabeling of progestational drugs with regard to their teratogenic risks? Was the epidemiological or teratology community at fault because they did not critique and respond to the early publications? Did the FDA act too slowly? The epidemiologic analyses, animal studies, and basic science principles have been reviewed, and it is obvious that clinically utilized progestational drugs do not cause nongenital malformations (i.e., LRDs and CHDs).

Toxicology of depot medroxyprogesterone acetate

Depo-Provera (depot-medroxyprogesterone acetate or DMPA), administered either subcutaneously or intramuscularly, has undergone a thorough toxicological evaluation in a number of animal species. DMPA has been tested in short- and long-term toxicity studies in rodents, rabbits, and monkeys. It has been examined for its effects on reproduction in mice, rats, and rabbits, and for carcinogenic potential in rats, mice, beagle dogs, and rhesus monkeys. Genotoxicity tests have been performed in vitro and in vivo. This paper describes the toxicology data submitted to the US FDA in support of the New Drug Application (NDA) for Depo-Provera as well as data published in the literature. When interpreted in the light of the available pharmacokinetic information, these data demonstrate that DMPA is not significantly different from other contraceptive progestogens in its toxic and tumorigenic potential.

Effect of gestational sex steroid exposure on limb development and endochondral ossification in the pregnant C57Bl/6J mouse: I. Medroxyprogesterone acetate

Although data supporting the teratogenic potential of intrauterine progestin exposure is lacking, concern persists among some individuals within the scientific community that these drugs have the potential for nongenital teratogenesis, especially with regard to limb reduction defects. Our laboratory has been interested in the ontogeny of steroid receptors in the developing embryo and in the role of steroid-receptor interactions in limb development, particularly the process of endochondral ossification. Since limb reduction defects can be produced from abnormal processes that are operative during organogenesis or during midgestation (vascular disruption) we have designed an animal study whereby embryos were exposed to sex steroids throughout organogenesis and fetal development. The present study assesses the effects of medroxyprogesterone acetate (MPA) on intrauterine endochrondral bone development specifically, as well as overall embryo-fetal development. Primagravid C57Bl/6J mice were treated via subdermal pellets which deliver MPA at dosages of 5.0, 50.0, and 500.0 mg/kg/day on gestational days 7 through 19. These doses were 25-, 250-, and 2,500-fold higher on a mg/kg basis than the human dose equivalent (HDE). No increases in nongenital malformations were noted at any evaluated MPA dosage level. At 25 X the HDE, MPA did not influence endochondral bone development as evidenced by a lack of significant effects on assessed bone growth parameters. In the 250- and 2,500-fold HDE dosage groups, MPA was shown to exert an embryotoxic effect inducing 48 and 100% resorptions respectively. Mean embryo weights/litter were significantly reduced by MPA exposure at 250 X the HDE. Intrauterine exposure to 250 X the MPA HDE induced reductions in humeral and femoral diaphyseal length in proportion to a reduction in overall growth. The data demonstrate that MPA, administered at dosages of up to several orders of magnitude in excess of the HDE and which permitted embryo survival, did not induce increases in the frequency of nongenital teratogenesis at any dose or gestational stage. Importantly, limb reduction defects were not noted even in instances where the dosage of MPA induced an inhibition of endochondral bone growth.

Central nervous system malformations induced by triamcinolone acetonide in nonhuman primates: pathology

Triamcinolone acetonide (TAC) was administered to pregnant macaques (Macaca mulatta [15] and M. radiata [7]) during gestational days (GD) 23 to 41 using various dosing schedules. A daily dose of 10 mg/kg is approximately equal to 100 x the human dose equivalent. The brains of the fetuses and infants were studied grossly and histologically. All cases displayed either the mild form of the TAC-induced syndrome (craniofacial dysmorphia, cranium bifidum occultum, meningocele, and mild distortion of the midbrain) or the more severe form (occipital encephalocele, hydrocephalus, severe distortion of the midbrain or midbrain "beaking," shunting of cerebrospinal fluid, and craniofacial malformations). The dysmorphology was dose-related, with severity increasing at higher doses or with increased numbers of treatments. Individual cases were assessed for the severity of the syndrome by comparison of like components between groups. The lesions observed were morphologically comparable to those described in spontaneous human cases; the TAC-induced occipital encephaloceles were associated with brainstem and cerebellar abnormalities, and, with the less severe form of the syndrome, brainstem abnormalities were occasionally present, with occipital meningoceles. Controversy exists concerning the significance and temporal development of the midbrain changes. However, the associated alteration in aqueduct conformation may have been responsible for functional compromise and ensuing hydrocephalus.

Embryotoxicity of sex steroidal hormones in nonhuman primates: II. Hydroxyprogesterone caproate, estradiol valerate

Two sex steroid compounds which have been used clinically for parenteral supportive therapy of pregnancy were examined for embryotoxic effects in rhesus and cynomolgus macaques. Hydroxyprogesterone caproate (HPC) alone or in combination with estradiol valerate (EV) were administered intramuscularly (i.m.) to pregnant monkeys at 7-day intervals between 20 and 146 days of gestation and fetuses were examined following cesarean section at 150 +/- 2 days. HPC alone was tested in both species at doses ranging from 0.01 X to 10 X the human dose equivalent (HDE); only rhesus monkeys were exposed to the HPC + EV combination at 0.1 X to 10 X HDE. Total embryolethality resulted following the administration of HPC alone and combined with EV at 1 X and 10 X HDE in rhesus monkeys; the level of abortions in cynomolgus monkeys exposed to HPC (0.1 X to 1 X HDE) was comparable to controls. A small number of nonspecific malformations and developmental variations observed in cynomolgus fetuses after HPC exposure were considered to be incidental findings. No anomalies were found in surviving rhesus monkey fetuses treated with HPC + EV. The results indicate that long-term in utero exposure to the progestin, HPC, alone or in combination with EV in rhesus and cynomolgus monkeys, is embryolethal but not teratogenic at doses up to ten times the human therapeutic dose.