Mononuclear-cell immunisation in prevention of recurrent miscarriages
: a randomised trial
Carol Ober, Theodore Kirrison, Randall R
Odem, Randall B Barnes, D Ware Branch, Mary
D Stephenson, Beverly Baron, Mary Ann Walker,
James R Scott, James R Schreiber
THE LANCET Vol 354 : 365-69 July31, 1999
Summary
Background Couples with unexplained recurrent miscarriage
may have an alloimmune abnormality that prevents
the mother from developing immune response
essential for the survival of the genetically
foreign conceptus. Immunisation with paternal
mononuclear cells is used as a treatment
for such alloimmune-mediated pregnancy losses.
However, the published results on this treatment
are conflicting. In this study (the Recurrent
Miscarriage [REMIS] study), we investigated
whether paternal mononuclear cell immunisation
improves the rate of successful pregnancies.
Methods Women who had had three or more spontaneous
abortions of unknown cause were enrolled
in a doubled-blind, multicentre, randomised
clinical trial. 91 were assigned immunisation
with paternel mononuclear cells (treatment)
and 92 immunisation with sterille saline
(control). The primary outcomes were the
inability to achieve pregnancy within 12
months of randomisation, or a pregnancy which
terminated before 28 weeks of gestation (failure);
and pregnancy of 28 or more weeks of gestarion
(success). Two analyses were done: one included
all women (intention to treat), and the other
included only those who became pregnant.
Findings Two women in each group received no treatment,
and eight (three treatment, five control)
were censored after an interim analysis.
In the analysis of all randomised women who
completed the trial, the success rate was
31/86(36%) in the treatment group and 41/85(48%)
in the control group (odds ratio 0.60 [95%
CI 0.33-1.12], p=0.108). In the analysis
of pregnant women only, the corresponding
success rates were 31/68(46%) and 41/63(65%;
odds ratio 0.45 [0.22-0.91], p=0.026). The
result were unchanged after adjustment for
maternal age, number of previous miscarriages,
and whether or not the couple had had a previous
viable pregnancy. Similar results were obtained
in a subgroup analysis of 133 couples with
no previous livebirth.
Interpretation Immunisation with paternal mononuclear cells
does not improve pregnancy outcomes in women
with unexplained recurrent miscarriage. This
therapy should not be offered as a treatment
for pregnancy loss.
Introduction
About 15% of clinically recognised pregnancies
are spontaneously aborted; thus, miscarriage
is the most common complication of human
pregnancy. Although most miscarriages are
sporadic, recurrent miscarriage (three or
more spontaneous abortions) occurs in 0.5-1.0%
of couples. In most women who experience
recurrent miscarriage, no cause can be identified.
Alloimmune mechanisms that prevent mothers
from developing immunological responses essential
for the survival of the semiallogeneic pregnancy
have been proposed as the cause of some or
all of these losses. On the basis of animal
models of abortion and studies of human organ
transplant survival, immunisation with paternal
white cells was proposed as a treatment for
alloimmune-mediated pregnancy loss. This
immunotherapy is offered by many medical
centres in the USA and elsewhere, although
its efficacy remains controversial. Published
trials and meta-analyses of published and
unpublished studies have yielded conflicting
results, indocating the need for largr randomised
trials. The purpose of this multicentre,
randomised, double-blind trial, the Recurrent
Miscarriage Study (REMIS), was to assess
the efficacy of immunisation with paternal
monomuclear cells as a treatment for unexplained
recurrent miscarriage.
Methods (È—ªj
Results
183 women were randomly assigned treatment
or placebo (figure 1). Two in each group
were disqualified: before immunisation, results
of screening indicated that one was pregnant
and one had a blood-group incompatibility;
two other couples decided not to take part
after randomisation (but before immunisation),
one because the husband was positive for
cytomegalovirus antibodies, and one for personal
reasons. 131(73.2%) of the 179 women became
pregnant within 12 months of randomisation,
40(22.3%) did not, and for eight the result
was indeterminate. Among the 131 pregnant
women, 72(55%) delivered and 59(49%) had
miscarriages. Among the 59 pregnancy failures,
five were ectopic, 31 were pre-embryonic,
17 were embryonic, and six were fetal.
The distribution of demographic and pregnancy
history variables in the treatment and control
groups is shown in table1. The groups were
similar except that a higher proportion of
women in the treatment group had had a previous
livebirth (p=0.054). This variable, along
with maternal age, and number of previous
losses, were included as covariates in subsequent
analysis.
In the intention-to-treat analysis, the
success rate was 36% in the treatment group
and 48% in the control group (table2; odds
ratio 0.60 [95% CI 0.33-1.12], p=0.108).
The corresponding analysis adjusted for maternal
age, number of previous miscarriages, and
previous livebirth gave a similar odds ratio
(0.54 [0.28-1.02], p=0.056). None of the
covariate effects reached satatistical significance,
although a previous livebirth was associated
with greater odds of success, of marginal
significance (2.05 [0.96-4.35], p=0.062).
Kaplan-Meier-estimated pregnancy rates did
not differ significantly between the groups:
78% in the treatment group and 72% in the
control group (log rank p=0.232).
In the analyses that included pregnant women
only, the success rate was 46% in the treatment
group and 65% in the control group (odds
ratio 0.45 [0.22-0.91], p=0.026). The corresponding
analysis adjusted for covariates again gave
a similar odds ratio (0.40 [0.19-0.84], p=0.015).
In this analysis, the number of previous
pregnancy losses had a significant effect
on success rate (odds ratio 0.75 per additional
loss [0.58-0.99], p=0.040). The treatment
effects were also similar among the participating
centres (data non shown).
Analyses were repeated for couples with
primary recurrent miscarriages-ie, couples
without a previous livebirth. The results
again favoured the control group, with success
rates in the intention-to-treat analysis
of 18/59(30%) in the treated group and 32/70(46%)
in the cintrols (odds ratio 0.52 [0.25-1.08].adjusted
p=0.082).Among pregnant patients, success
rates were 18/46(39%) and 32/51(63%) in the
treatment and control groups, respectively
(0.37 [0.16-0.86], adjusted p=0.021). In
the treatment group, 26% of patients developed.
HLA antibodies after immunisation. There
was no evident association between success
rate and HLA-antibody status (31% and 30%
for patients with and without HLA antibodies
after immunisation, respectively, p=1.0).
The distriutions of time from pregnancy
to miscarriage in the treatment and control
groups are shown in figure 2. The mean durarion
of gestation at the time of misacarriage
was 8.9 weeks (SD 4.5) and 6.2 weeks(1.5)
in the treatment and control groups, respectively
(p=0.002). The duration of gestation at which
miscarriage occurred was before 10 weeks
in all patients in the control group, whereas
six(16%) of 37 losses in the treatment group
occurred after 10 weeks of gestation. The
timing of pregnancy loss by stage of development
is shown in the tabke 3. Ectopic, pre-embryonic,
and embryonic loss rates did not differ significantly
between the treatment and control group (p=0.320,
0.564, and 0.162, respectively), but the
rate of fetal loss was significantly greater
in the treatment group (p=0.036).
Chromosome studies in the products of conception
were successful for 21 of the 59 abortuses.
Seven(33%) of the 21 abortuses on which cytogenetic
studies were done had abnormal karyotypes;
all were in the treatment group (table 3).
Four additional fetuses in the treatment
group had abnormalities: two had a cystic
hygroma; one had an omphalocele, a tracheo-oesophageal
fistula, duodenal atresia, and a single umblical
artery; and one had an abnormal triple screen
(ƒ¿-fetoprotein, unconjugated oestriol, and
human chorionic gonadotropin).
There were no pregnancy losses or fetal
deaths after 28 weeks of gestation. There
were no differences with respect to delivery
statistics between infants born to mothers
in the treatment group (31 liveborn) and
those born to mothers in the control group
(41 liveborn). The mean gestational ages
at delivery were 39.2 weeks (SD1.7: range
35.6-44.4) in the treatment group and 39.4
weeks (1.3; 36.4-41.0) in the control group
(p=0.698). The mean birthweights in the two
groups were 3395g (623; 2241-4592) and 3353g
(491; 2381-4479), respectively (p=0.755).
Sex ratio (M/F) was 0.82 in the treatment
group and 0.86 in the control group (p=1.0).
Discussion
In the REMIS study, the pregnancy success
rate was higher in the control group than
in patients immunised with paternal monomuclear
cells, irrespective of whether all randomised
patients or only patients achieving a pregnancy
were considered, or whether or not patients
with previous liveborn children were excluded. In addition,
outcomes were similar among patients in the
treatment group irrespective of whether they
developed HLA antibodies after immunisation.
Thus, we found no evidence of benefit from
immunisation with paretnal monomuclear cells
for prevention of recurrent miscarriage.
Furthermore, higher rates of pregnancy loss
omong patients immunised with paternal cells
than those immunised with saline suggests
that immunotherapy with paternal monomuclear
cells may increase the rate of clinically
recognised pregnancy losses.
The higher rate of miscarriage in the treatment
group was associated with losses occurring
later in gestation. Indeed, all losses occurring
after 9 weeks of gestation were in the treatment
group (figure 2). All chromosomal and other
abnormalities also occurred in the treatment
group. However, this finding probably reflects
the greater chance of identifying fetal tissues
in the products of conception later in gestation,
and the larger number of later pregnancy
losses in the treatment group. For example,
in this study, chromosome analyses were successful
in five(16%) of 31 pre-embryos, 11(65%) of
17 embryos, and four(67%) of six fetuses
(table 3). Extrapolation of epidemiological
studies of chromosome abnormalities in abortuses
suggests that a significant proportion of
the earlier losses were chromosomally abnormal.
However, without knowledge of the chromosomal
status of all abortuses we cannot confine
our analyses to chromosomally normal pregnansies.
Nevertheless, given the almost identical
maternal age distribution among the treatment
group (table 1), the occurrence of chromosome
abnormalities should have been randomly distributed
among the groups.
The results of this study difer from those
of the smaller clinical trial by Mowbray
and cokkeagues. Althoough we followed an
almost identical protocol, there were some
differences between the studies. First, the
previous study used matermal monomuclear
cells from 10mL blood as the control treatment,
whereas we used sterile saline. Because of
the lower than expected pregnancy success
rate in the control group in that study (37%),
we chose to use saline, as in the trial of
Cauchi and colleagues. Second, Mowbray and
colleagues' trial did not provide first-trimester
supportive therapy. The use of saline as
a placebo and the provision of supportive
therapy in the first trimester could account
for the greater success rate in our control
group than in Mowbray and colleagues' study
(65 vs 37%, respectively, among pregnant
women), although the success rate in our
control group is similar to success rate
reported in epidemiological and cohort studies
of women with recurrent miscarriage. However,
these differences in our protocols are unlikely
to account for the disparity in success rates
in the treatment groups between the two studies
(46 vs 77%, respectively, among pregnant
patients). On the other hand, differences
in experimental design and analysis could
explain some of the differences between our
studies. Mowbray and colleagues used a fully
sequential design (stopping early) and did
not analyse by intention to treat, as we
did, which may have biased the outcome if
either pregnancy rates or rates of preclinical
pregnancy losses differed between the two
groups. Also, when 18 more patients in Mowbray
and colleagues' study (analysed by Jeng and
colleagues) were followed up after their
trial had stopped, the treatment effect was
lower, and the differences between treated
patients and controls were not significant.
In one meta-analysis, which included published
and unpublished data from the study of Mowbray
and colleagues and from several additional
randomised trials, a small but significant
effect in favour of leucocyte immunotherapy
was found. In this analysis, the success
rates in treated women ranged from 62% to
77% (pooled sample, 68.4%). Results were
reported on a relative-risk scale-ie, as
the ratio of livebirth rates in treated and
control groups. In that paper, two analysis
teams worked independently and arrived at
estimated ratios of 1.16 (95% CI 1.01-1.34)
and 1.21 (1.04-1.37), respectively. In a
1995 meta-analysis including updated data
from these trials, the effect of immunotherapy
did not reach significance (livebirth rate
ratio 1.12 [0.97-1.31] ). If the results
from our trial are added to these data, the
estimated livebirth rate ratio falls to 1.04
(0.91-1.20). A test for heterogeneity of
the results across the trials was not significant
(p=0.320).
In this study, immunisation with paternal
mononuclear cells did not improve pregnancy
outcome in women with recurrent miscarriage.
Despite a history of unexplained recurrent
miscarriage, nearly 65% of control patients
who became pregnant had a successful pregnancy.
We found a higher rate of miscarriage and
a greater gestational age at the time of
loss in immunised women who became pregnant.
Because of the lack of benefit, we recommend
against this intervention as a treatment
for unexplained recurrent miscarriage.