Dr. Maria Pia Amato
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.
Dr. Jiwon Oh
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).