AT THE AAN 2016 ANNUAL MEETING
VANCOUVER (FRONTLINE MEDICAL NEWS) – Three types of drugs commonly used to treat multiple sclerosis (MS) appear to have a generally good safety profile when administered before and during early pregnancy, suggest a trio of studies reported at the annual meeting of the American Academy of Neurology.
Exposure to interferon-beta during the first trimester did not increase the risks of miscarriage, congenital anomalies, or birth weight. And although use of natalizumab led to higher odds of spontaneous abortion as compared with interferon-beta or no therapy, the absolute rate still fell within that of the general population. Pregnancies occurring weeks to years after treatment with alemtuzumab also had rates of spontaneous abortion, birth defects, and stillbirth on par with population values.
All three drugs fall in a gray area when it comes to use in pregnancy, with a Food and Drug Administration designation of category C, indicating that animal studies have shown adverse effects on the fetus and adequate, quality human data are lacking, but potential benefits may outweigh potential harms in pregnancy. The studies’ findings are therefore likely to be informative to women of reproductive age, a group disproportionately affected by MS.
“It’s very important to collect as much data as possible about potential exposure risks with disease-modifying therapy in pregnancy,” session comoderator Dr. Jennifer Graves , a neurologist at the Multiple Sclerosis Center at University of California–San Francisco Medical Center and UCSF Benioff Children’s Hospital, San Francisco, said in an interview.
“However, all studies have the limitation of sample size,” she added. “The majority of serious adverse effects – teratogenicity, major birth defects – may be less than 1 in 500 [in frequency]. So this is something that puts all of these studies into context because we just don’t have that many pregnancies that have been exposed to some of these agents.” The method whereby miscarriages are ascertained can also influence findings.
Nonetheless, this research is critical for women and their physicians when it comes to making decisions about treatment, Dr. Graves maintained. “Although pregnancy may be protective for many women with MS, many do need treatment during their pregnancy to prevent severe relapses due to various factors. Collecting this type of information is important.”
Interferon-beta safety
In the first study, investigators led by Dr. Sandra Thiel of Ruhr University Bochum and the Heinrich Heine University Düsseldorf, both in Germany, analyzed data from the German Multiple Sclerosis and Pregnancy Registry.
They studied pregnancies among women who had at least 12 months of postpartum follow-up. Exposure to interferon-beta (brand names Rebif, Avonex, Betaseron, and Extavia) was defined as injection of the drug at any time after the last menstrual period.
In all, 251 pregnancies exposed to interferon-beta were compared with 194 pregnancies not exposed to any disease-modifying drugs. The median duration of exposure in the former group was 32 days, indicating that most women stopped the drug soon after discovering they were pregnant, Dr. Thiel noted.
Study results, reported at the meeting and recently published (Mult Scler. 2016 Feb 26. doi: 10.1177/1352458516634872 ), showed that the rate of miscarriage was 9.96% in the exposed group and 7.73% in the unexposed group, and the rate of congenital anomalies among live births was 3.08% and 5.52%.
In analyses using propensity score adjustment, there were no significant differences between groups in the odds of live birth, spontaneous abortion, congenital anomalies, preterm birth, cesarean section, or small for gestational age, or in mean infant birth weight.
Of note, the women whose pregnancies were not exposed to any disease-modifying therapy had a higher rate of relapse during pregnancy when compared with counterparts whose pregnancies were exposed to interferon-beta (27.3% vs. 14.3%).
“Taken together with the existing literature, our study provides further reassurance that interferon-beta treatment can be safely continued up until the time when women with MS become pregnant,” Dr. Thiel concluded. The safety profile seen “is consistent with the pharmacologically plausible safety of interferon-beta, as interferon-beta is a huge molecule that cannot pass the placental barrier.”
“Since the vast majority of women stopped the interferon-beta treatment during the first trimester of pregnancy, we cannot draw any conclusions about the safety of interferon-beta later in pregnancy,” she cautioned. “Another limitation is the variability in the gestational week of entry into the cohort, as later than first-trimester inclusion can lead to an underestimation of early events, particularly spontaneous abortions.”
Natalizumab safety
In the second study, Dr. Maria Pia Amato , Department of NEUROFARBA, Section of Neurosciences, University of Florence, Italy, and her colleagues with the Italian MS Study Group assessed pregnancy outcomes after exposure to natalizumab (Tysabri). This antibody targets alpha-4 integrins, which play a role in a variety of pregnancy processes and in fetal hematopoiesis and cardiac development, she noted.
They identified women for the study using two sources: the prospective Italian Pregnancy Dataset of consecutive female patients with MS referred to 25 centers and a cohort of women from an Italian interferon-beta study.
In all, they compared 65 pregnancies exposed to natalizumab (any treatment from 8 weeks before the start of the last menstrual period onward), 88 exposed to interferon-beta as a control, and 339 not exposed to either. The mean duration of natalizumab exposure was 1.16 weeks, and the mean duration of interferon-beta exposure was 4.6 weeks.
Results showed that the rate of spontaneous abortion was higher for natalizumab-exposed pregnancies, at 18.5%, than for interferon-beta–exposed pregnancies, at 8%, and for nonexposed pregnancies, at 6.5% (P = .006). But the timing of these abortions was similar, at about 8 weeks of gestation.
In adjusted analyses, natalizumab exposure was still associated with an elevated risk of spontaneous abortion when compared with interferon-beta or no exposure (odds ratio, 3.9). However, the 18.5% rate seen with the antibody fell within the range for the Italian general population of 4.8% to 21.1%.
Infants in the natalizumab group had the lowest birth weight and length, while infants in the interferon-beta group had the youngest gestational age. The groups did not differ significantly with respect to the incidence of birth defects; however, with a single defect seen in each, the study was underpowered to assess differences in this outcome.
Data additionally showed that discontinuation of natalizumab in advance of pregnancy led to an uptick in relapses, with 30% of women having a relapse, according to Dr. Amato. “This increase started during the first trimester of pregnancy and culminated in the second trimester of pregnancy. All the women were retreated soon after delivery with natalizumab, and disease activity returned to the pre-pregnancy period level with resumption of the drug.”
“Patients and clinicians should discuss together and balance the potential risks to the fetus with natalizumab exposure with the potential risks to the mother of disease reactivation during pregnancy,” she recommended, cautioning that the findings were based on first-trimester exposure of short duration. “Decisions should be made case by case on the basis of the disease activity in a specific patient and the availability of alternative treatment, and whether to use a conservative approach, stopping the drug and respecting the washout period, or in a few cases, an active approach, continuing the drug till conception or even discuss continuing the drug during pregnancy.”
Alemtuzumab safety
In the third study, investigators led by Dr. Jiwon Oh of the division of neurology at the University of Toronto analyzed outcomes of pregnancies among women who had been treated with alemtuzumab ( Lemtrada ), an antibody that targets CD52.
Treatment with alemtuzumab leads to depletion of lymphocytes followed by reconstitution of the immune system with a less inflammatory profile. “This is thought to contribute to the durable efficacy in the absence of continuous treatment with alemtuzumab,” she explained. “This durable efficacy and the fact that you may not need to redose is relevant when you are thinking about pregnancy in patients with MS, just because this is a drug that is given in two different cycles and may not need to be readministered.”
Although the antibody becomes undetectable in serum about 30 days after administration, it is unclear whether the ongoing immune reconstitution has any impact on subsequent pregnancy, Dr. Oh said.
The investigators pooled data from the phase II CAMMS223 trial and the phase III CARE-MS I and CARE-MS II trials of alemtuzumab and their extension phases. Women enrolled in the trials were required to use effective contraception during treatment and for the next 6 months.
Dr. Oh reported interim results based on 200 pregnancies among 137 women. Most pregnancies occurred at least 4 months after the last dose of alemtuzumab; only four occurred within 1 month and another four occurred 1 to 3 months after the last dose.
Among the 181 completed pregnancies with known outcomes, 67.4% resulted in live births. Another 21.5% ended in spontaneous abortion. “Although this is on the higher end of normal, it is still in keeping with what is seen in the general population,” Dr. Oh noted.
The rate of stillbirth was 0.6%, also at the upper end of the range seen for the general population. Finally, 10.5% of the pregnancies ended in elective abortion.
There were no congenital anomalies or birth defects among the live-born infants. One was seen in an electively terminated pregnancy (26 months after the last dose), and another was seen in a stillbirth (4 years after the last dose).
“Two out of 200 is 1%, and this is actually lower than what is normally seen in the general population, approximately 3% to 7%,” Dr. Oh commented.
“To date, there is no indication of an increased risk for congenital anomalies or birth defects in infants,” she summarized. “There has also been no indication of increased rates of spontaneous abortion in women who become pregnant, but obviously, these data are limited because we don’t necessarily have a control group.”
“Based on the pharmacokinetics of alemtuzumab and labeling guidelines, women of childbearing potential should continue to use contraception for 4 months after receiving a course of alemtuzumab,” Dr. Oh concluded. “There is an international Alemtuzumab Pregnancy Exposure Registry that is open and enrolling patients who become pregnant between the first dose of alemtuzumab and 4 months after the last infusion, and hopefully this will give us more information to confirm some of the observations that we see here.”
Dr. Thiel disclosed that she had no relevant conflicts of interest; the German Multiple Sclerosis and Pregnancy registry was partly supported by Bayer Healthcare, Biogen Idec Germany, Merck Serono, Novartis Pharma, Teva Pharma, and Sanofi-Aventis/Genzyme Pharmaceuticals. Dr. Amato disclosed that she has received research grants and honoraria as a speaker from and is a member of advisory boards for Bayer, Biogen Idec, Merck Serono, Novartis, Sanofi Genzyme, Teva, Almirall, and Roche; the study did not receive any financial support. Dr. Oh disclosed that she serves on the scientific advisory boards or is a speaker for Biogen Idec, EMD Serono, Genzyme, Novartis, Roche, and Teva; the study was supported by Genzyme and Bayer Healthcare.
