1 Center of Reproductive Medicine, Hôpital Jean Verdier, Bondy, France, 2 IVF & Genetics, Athens, Greece, 3 Lin Professional Clinic, Haifa, Israel, 4 Hospital Clinic de Barcelona, Barcelona, Spain, 5 Edinburgh Royal Infirmary, Edinburgh, UK and 6 Hospital Universitario La Fe, Valencia, Spain
7 To whom correspondence should be addressed at: Center of Reproductive Medicine, Hôpital Jean Verdier, Av du 14 Juillet, Bondy, 93143, France. Email: jean-noel.hugues{at}jvr.ap-hop-paris.fr
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Abstract |
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Key words: anovulation/follicular growth/recombinant human FSH/recombinant human LH
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Introduction |
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However, although follicular growth can be induced by FSH in the total absence of LH, there is also some evidence that optimal follicular development requires a minimal exposure to LH to ensure adequate estradiol (E2) production, full oocyte maturity, follicular rupture and the ability for granulosa cells to be luteinized in response to hCG (Couzinet et al., 1988; Glasier et al., 1988
; Shoham et al., 1991
; Balasch et al., 1995
). As demonstrated in patients suffering from severe deficiency in LH and FSH, daily injections of low doses of recombinant human LH (rLH; 75 IU) are required to ensure optimal follicular maturation (European Recombinant Human LH Study Group, 1998
).
LH receptors appear on granulosa cells that have been adequately stimulated by FSH and the developing follicle becomes increasingly dependent on LH (Richards et al., 1987). In the granulosa cells of the pre-ovulatory follicle, aromatase is functionally coupled to the LH receptors such that LH directly regulates follicular estrogen secretion (Zeleznik and Hillier, 1984
; Zeleznik, 2001
). Consequently, substitution of FSH by LH therapy in the late follicular phase is able to maintain adequate steroidogenesis (Sullivan et al., 1999
) and even final stages of follicular maturation (Balasch and Fábregues, 2003
).
On the other hand, the concept of an LH ceiling was initially based upon clinical observations that follicles exposed to inappropriately high concentrations of LH enter atresia or become prematurely luteinized, and oocyte development may be compromised (Howles et al., 1986; Chappel and Howles, 1991
; Jacobs, 1991
). The dose dependence of this LH effect was illustrated by studies in vitro: low-dose treatment with LH serves generally to enhance steroidogenesis without inhibiting DNA synthesis, but high-dose LH causes enhanced synthesis of progesterone, suppression of aromatase activity and inhibition of cell growth (Overes et al., 1992
; Yong et al., 1992
). Thus, developing follicles appear to have finite requirements for stimulation by LH, beyond which normal development ceases.
Whereas each follicle has a threshold beyond which it must be stimulated by FSH to initiate pre-ovulatory development (Brown, 1978), it may also have a ceiling within which it should be stimulated by LH, above which normal development is terminated (Hillier, 1993
). During the second half of the follicular phase, as plasma FSH concentrations decline, the LH-dependent phase of pre-ovulatory follicular development only proceeds normally if LH is present at concentrations beneath this ceiling value (Hillier, 2000
). When the ceiling is exceeded at the mid-cycle surge of LH, further division of granulosa cells would cease as luteinization proceeds (Hillier, 1994
).
In this respect, the potential effect of LH administration in controlling the number of developing follicles deserves clinical investigation. Recently, Loumaye et al. (2003) provided evidence that rLH alone can trigger follicular growth arrest in WHO group I or II anovulatory patients. Therefore, rLH may be of particular use in treatment regimens that aim to achieve mono-ovulation for conception in vivo. However, the optimal dose of rLH required to induce atresia of secondary follicles is still not established.
The objective of this prospective, randomized, double-blind, multicentre study was to evaluate the effects of four different doses of rLH administered in the late follicular phase and to establish the minimal effective dose required to promote maturation and ovulation of a single follicle while inducing atresia in secondary follicles.
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Materials and methods |
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Study design
The study was conducted according to Good Clinical Practice guidelines, and ethical committee approval was obtained to conduct the study in all participating centres.
To be eligible, patients were to have been stimulated with urinary FSH (uFSH) or recombinant FSH (rFSH) for ovulation induction and have started FSH treatment within 5 days of spontaneous or induced menstruation. The starting dose of FSH was chosen to achieve follicular recruitment without exceeding a daily dose of 150 IU according to the BMI. Women were enrolled in the study if they were experiencing an excessive follicular response to FSH stimulation treatment attested by the presence on ultrasound of at least three follicles 1115 mm in diameter, but no follicles >15 mm in diameter at any point during stimulation with FSH. Patients were then randomized to receive rLH or placebo in combination with 37.5 IU of rFSH daily from the day of randomization (S1) until the criteria for hCG administration were reached, or for a maximum of 7 days (S7). The treatment period could be interrupted before completion if obvious regression of all follicles was recorded or if the patient was at risk of developing ovarian hyperstimulation syndrome (OHSS). A single injection of hCG (5000 IU) was given within 36 h of the last rLH or placebo/rFSH injection if monitoring by ultrasound showed a maximum of two follicles with a mean diameter 16 mm and if the total follicular number and the serum E2 levels were not indicative of OHSS risk.
Randomization and medications used
Either urinary FSH (Metrodin® or Metrodin HP®; Serono, Switzerland) or rFSH (Gonal F®; Serono) were used for the initial part of the ovarian stimulation cycle, prior to randomization. Doses of rLH (Luveris®; Serono) were selected for each patient in a randomized fashion, without any stratification per treatment group. Subcutaneous administration of 37.5 IU rFSH in addition to the rLH or placebo injection was performed in every case, whatever the amount of FSH used during the stimulation period prior to randomization.
rLH/rFSH administration was started on the day of randomization (S1), once eligibility had been confirmed and the patient had given her informed consent for entry into the study. Patients were randomized to one of the following treatments, all administered daily by subcutaneous injection: (i) placebo; (ii) 6.8 µg (150 IU) rLH; (iii) 13.6 µg (300 IU) rLH; (iv) 30 µg (660 IU) rLH; (v) 60 µg (1325 IU) rLH. rLH or placebo treatment assigned to each patient was determined according to a computer-generated randomization list stratified by centre. A single injection of 5000 IU hCG (Profasi®; Serono) was given when the criteria for triggering ovulation were met, as described above.
Monitoring
Monitoring was primarily performed by vaginal ultrasonography. The examinations were performed weekly prior to the administration of rLH/placebo and daily during the treatment period. All follicles with a mean diameter (i.e. the mean of the two longest perpendicular diameters) >10 mm were recorded according to their size. Whenever possible, the individual growth over time of each follicle with a diameter 11 mm was recorded.
Blood samples were taken for local E2 measurements during the whole period and for retrospective analysis of E2, progesterone, LH and inhibin A and B, prior to administration of rLH/placebo and on a daily basis up to the day of hCG administration (or the last day of gonadotrophin treatment if no hCG was administered). The luteal phase was assessed and monitored by measuring progesterone serum values between day 6 and day 8 post-hCG.
Hormone assays
All assays were performed at a central laboratory: LCG Bioscience Clinical (Science Department, Bourn Hall Clinic, Bourn, Cambridge, UK). Serum FSH and LH were measured using a validated, commercially available immunoradiometric assay (IRMA) method (MAIAClone; Serono). The limit of quantification for serum FSH and LH was 1 IU/l. Serum E2, progesterone, inhibin A and inhibin B were measured using validated commercially available immunoassays. Centralized immediate safety biochemistry and haematology analyses were performed by Covance CLS (Covance Central Laboratory Services SA, Switzerland, Australia and USA).
Study endpoints and sample size calculation
The primary efficacy endpoint of the study was the proportion of patients who received hCG and who had exactly one follicle 16 mm in diameter. The main secondary efficacy endpoints were: (i) proportion of patients who received hCG according to the protocol criteria; (ii) mean number of pre-ovulatory follicles (
16 mm in diameter) on the day of hCG; (iii) mean number of medium-sized follicles (between 11 and 15 mm in diameter); (iv) difference between the number of baseline follicles compared with the number of pre-ovulatory follicles on the day of hCG; (v) longitudinal follicular growth (where possible); (vi) frequency of ovulation (luteal phase progesterone levels
25 nmol/l); (vii) clinical pregnancy rate and outcome.
It was planned to enrol a total of 150 evaluable patients (30 patients per group). This number was based upon the results obtained from previous studies carried out in the same patient population, assuming 80% power and 5% significance level (two-sided) for the proportion of patients/cycle with exactly one follicle 16 mm in diameter.
Statistical methods
The statistical method used depended on the nature of the variable analysed. As one of the main objectives of the study was to find the minimal effective dose of rLH, the primary analysis carried out was that of a dose relationship, with a linear modelling using treatment received as a factor for comparison. A parametric model (logistic regression) was computed in order to perform the dose relationship and subsequent pairwise comparisons. Paired comparisons were carried out between placebo and each of the doses of rLH and then between each rLH dose and each of the subsequent dosing regimes. All secondary endpoints were analysed using the same methods of statistical analysis described above. Other statistical tests such as analysis of variance, logistic regression, exact logistic regression, CochranMantelHaenszel or Fisher's exact test were used as appropriate. Due to observed differences between treatment groups in BMI and dose of FSH prior to randomization, the analysis of the primary endpoint was adjusted for these parameters in order to better evaluate treatment effect.
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Results |
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The main demographic parameters of the 147 analysed patients were statistically balanced between treatment groups as regards past medical history, current medical condition, associated infertility factors, obstetric history, and baseline hormonal parameters. A total of 132 (89.8%) patients had been previously stimulated with clomiphene citrate and/or gonadotrophins (Table I). The proportion of previously stimulated cycles (mean of 3.2 clomiphene citrate and mean of 2.0 gonadotrophin cycles) was also balanced between treatment groups.
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The primary efficacy endpoint of the study was the proportion of patients who received hCG and who had exactly one follicle 16 mm in diameter on that day. Of the 147 randomized patients, 34 (23.1%) met these two criteria. Within the treatment groups, the proportion of patients meeting these criteria ranged from 13.3% in the placebo group to 32.1% in the 30 µg rLH group (Table II). After controlling for BMI and the dose of FSH, pairwise comparison of the 30 µg rLH group versus placebo showed a significant difference (P=0.048).
Table II shows the secondary efficacy endpoints for the 94 patients who received hCG according to the protocol criteria (maximum of two follicles with a mean diameter 16 mm). The proportion of these patients was slightly higher in the 30 µg rLH-treated group than in the 60 µg rLH-treated group. The number of follicles
16 mm in diameter on the day of hCG ranged from one to two with 1.6±0.5 follicles in all the rLH groups and 1.8±0.4 follicles in the placebo group. This difference did not achieve significance. Furthermore, the number of small follicles (410 mm) was not significantly different between treatment groups.
If we consider the hormonal parameters at the time of hCG administration (Table III), the statistical analysis showed no significant difference for E2 values but significantly higher mean levels for LH in the 60 µg rLH group compared with placebo (P=0.007). Inhibin A and B mean values on the day of hCG administration were not significantly different between groups. However, significant differences in inhibin B were detected 2 days before hCG administration, due to a high inhibin B level in the placebo group (1223.3±1185.5 pg/ml, compared with 537.3±460.1 pg/ml in the 6.8 µg group (P=0.013 versus placebo), 557.5±459.8 pg/ml in the 30 µg group (P=0.031) and 500.0±561.5 pg/ml in the 60 µg group (P=0.012).
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The pregnancy rate was evaluated in the overall population. Twenty-seven of the 147 (18.4%) patients had at least one serum hCG >10 IU/l. Within treatment groups, the proportion of patients ranged from 10.3% in the 60 µg rLH group to 28.6% in the 30 µg rLH group, while being 20% in the placebo group, 18.8% in the 6.8 µg rLH group and 14.3% in the 13.6 µg rLH group. The difference between treatment groups was not significant. Among the 23 clinically pregnant patients, 17 (73.9%) had exactly one fetal sac seen on ultrasound scan, while five (21.7%) had two fetal sacs, and one (4.3%) had three fetal sacs. Distribution of patients according to the number of sacs was balanced across treatment groups. Although the proportion of patients who had two fetal sacs was higher in the 30 µg rLH group, the statistical analysis did not show any particular dose relationship. Of the 23 patients who had a clinical pregnancy, one had both an intrauterine and extrauterine pregnancy. This was surgically treated. Another patient had a miscarriage after visualization of a fetal sac.
Safety evaluation
All 153 patients who received treatment were included in the safety analysis.
Local tolerability reactions were reported for 26 (17.0%) patients. Swelling and bruising were the most frequent types of reactions. Five (3.3%) patients had OHSS: two in the 6.8 µg rLH group and one each in the 13.6, 30 and 60 µg rLH groups. Four OHSS events were of mild severity and one was graded as a severe event. Overall, there was no statistically significant difference in OHSS between LH-supplemented patients (5/117 or 4.3%) versus those women receiving placebo (0/30) (P=0.6, Fisher's exact test). The proportion of patients who had adverse events was balanced between groups, as well as distribution of severity and relationship with study drug. No patients had clinically abnormal values for any of the haematology and biochemistry parameters on days 68 post-hCG. Analyses of anti-rLH antibodies were negative for the overall population.
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Discussion |
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Our data extend the LH ceiling concept to clinical practice and confirm the results of a recently published pilot study (Loumaye et al., 2003). In that study, WHO group II anovulatory patients were given placebo, or 225 or 450 IU rLH, without addition of any FSH support, if they presented an over-response to FSH, defined by the presence of four or more follicles that were
8 and <13 mm in diameter. Follicular growth arrest was only observed in patients treated with rLH (5/12), as attested by a reduction in the adjusted mean number of follicles
14 mm in diameter. Moreover, while placebo treatment was not associated with significant changes in serum E2 levels, administration of rLH alone led to a further increase in serum E2 levels, as previously described by Sullivan et al. (1999)
. However, some patients with follicle regression presented a sharp decline in serum E2 levels, which could be related to the absence of FSH support during the late follicular phase.
Our study was set up to establish the minimal effective dose required to induce atresia of secondary follicles, whilst supporting the growth of a dominant follicle to pre-ovulatory conditions. To facilitate this, a low dose of FSH was added to the rLH/placebo treatment. According to our data, 30 µg rLH seems to be the most appropriate dose to reduce the size of the developing cohort. Indeed, the proportion of patients who received hCG and who had exactly one follicle 16 mm in diameter was significantly higher among patients treated with 30 µg rLH compared with the placebo group. No statistically significant dose effects were detected for these secondary outcome measures, possibly because of the relatively small number of patients in each group. Even if we cannot exclude the possibility that the reduction in the FSH dose may have contributed to follicular atresia, it seems to be unlikely due to the pharmacokinetic and pharmacodynamic properties of FSH preparations (Le Cotonnec et al., 1994
). Therefore, our data suggest that 30 µg rLH is the minimal effective dose required to induce arrest of large follicle development.
Another report on the consequences of LH activity on the dynamics of folliculogenesis has been previously reported by Filicori et al. (2002). In that study, administration of increasing doses of hCG (from 50 to 200 IU) from the mid-follicular phase can significantly reduce the number of small follicles without any change in the number of large follicles.
However, many discrepancies exist on the design of these experiments and may explain the opposite conclusion. First, the difference in the pharmacokinetic properties of the drugs used may account for the divergent effects. Indeed, the half-life of hCG is much longer than that of LH (36 versus 11 h) (Trinchard-Lugan et al., 2002
). Second, the design of the study performed by Filicori et al. differed from our own because a hypogonadotrophic state was induced prior to ovarian stimulation through a GnRH agonist administration. Therefore, the considerable difference in endogenous LH secretion resulting from these two protocols means that the effectiveness of exogenous LH supplementation cannot be strictly compared. Most importantly, in Filicori et al.'s study, administration of hCG preparations was started on a fixed day (day 7) of the ovarian stimulation, without any criteria of follicular growth. As LH receptors only appear on differentiated granulosa cells (Richards et al., 1987
), it is uncertain whether the effects of hCG preparations on follicular growth were actually related to a direct LH effect on granulosa cells.
The purpose of our study was to address the issue of the direct effects of LH on follicular growth. Therefore, rLH was administered when follicles reached 1115 mm in diameter (i.e. when LH receptors are constantly expressed on differentiated granulosa cells) (Richards et al., 1987). However, while this design allowed us to more specifically assess the direct effect of LH supplementation on follicular growth, we cannot exclude that the parallel stimulatory effect of LH on androgen secretion may also interfere with the control of follicular growth.
Another interesting finding from our study concerns the dose-related effect of LH on the luteinization process of granulosa cells. Our data clearly indicate that administration of rLH at a daily dose up to 30 µg does not induce premature luteinization. In contrast, a dose of 60 µg rLH was consistently associated with an increase in progesterone values. These findings provide evidence for a pivotal role of LH in the process of luteinization, and for an LH ceiling effect at >30 µg daily dose.
While other studies reported a relationship between the administered dose of FSH and follicular phase progesterone values (Ubaldi et al., 1996; Filicori et al., 2002
), our results strongly suggest that LH plays a key role in this process. They also show that the dual effects of LH on the luteinization process and on the control of follicular growth are not equivalent, as the dose required to exert control upon follicular growth is slightly lower than that effective to induce luteinization. Our results contrast with the data provided by Filicori et al. (2002)
, who reported a slight but significant increase of progesterone values in the whole group of patients treated with hCG and did not observe any dose-dependent effect of hCG preparations. This discrepancy may be related to the different pharmacokinetic properties of both preparations. They also emphasize that conclusions drawn from studies using hCG preparations cannot be applied to those performed with rLH.
Finally, our study shows that, while the clinical pregnancy rate was slightly higher in patients treated with 30 µg rLH, the increase in progesterone secretion induced by a dose of 60 µg rLH may have accounted for the reduction in the pregnancy rate of that group. No clear benefit was observed on the risk of multiple pregnancy rate. This may be related to the small number of patients in each treatment group and further studies are required to investigate whether addition of LH bioactivity is actually effective to prevent the risk of multiple pregnancy.
In summary, this randomized, placebo-contolled, dose-finding study shows that, in patients over-responding to FSH during ovulation induction, doses of rLH up to 30 µg/day are well tolerated in the late follicular phase and appear to increase the proportion of patients developing a single dominant follicle. Our data support the LH ceiling concept, whereby addition of a high dose of LH is able to control follicular growth by inducing atresia of developing follicles.
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Acknowledgements |
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Notes |
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References |
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Submitted on March 4, 2004; resubmitted on October 14, 2004; accepted on November 9, 2004.