**4. Recombinant luteinizing hormone**

The advent of recombinant DNA technology eventually led to the availability of recombinant LH in clinical practice (80). Urinary isolation of LH is an inefficient process, with 60-250 IU/mg of protein isolate (81). Conversely, recombinant LH contains 20,000 – 30,000 IU/mg of protein (81). The pharmacodynamics of recombinant and urinary derived LH preparations show similar clearance, half-life, and concentration curves (16, 81). The pharmacodynamics profiles of rLH are similar whether it is administered subcutaneously or intramuscular and it does not impact the pharmacodynamics of co-administered rFSH (82- 84). In hypogonadotropic hypogonadal patients, a dose of 75IU of rLH has been demonstrated to promote adequate folliculogenesis when administered with FSH (85). rLH has potential advantages over the LH activity in hMG in that there is less risk of protein contamination and allergic reaction and it allows for the LH dose to be specifically adjusted without affecting the FSH dose.

There are numerous RCT evaluating rLH plus rFSH versus rFSH alone, but the data is complicated by significant heterogeneity between the trials (29, 30, 36-41, 86-95). The fact that the rLH dose can be administered at a separate starting time and doses from the rFSH dose has allowed researchers and clinicians to be more varied in the approach to rLH administration as compared to hMG. While this has allowed for the investigation of interesting protocols, it makes interpretation and meta-analysis of the data more complex. rLH has been investigated as a priming agent started up to 7 day prior to rFSH administration, as an early follicular phase agent beginning on days 1-3 of rFSH, and as a late follicular agent starting day 5-8. The dosing of rLH has also varied from 75IU to 300IU per day or as a fixed ratio to the FSH dose.

Three RCT have shown higher implantation or pregnancy rates in women receiving rLH supplementation (24, 38, 94). Patients with an inadequate response to rFSH alone have also been shown to benefit from the addition of 150IU of rLH as compared to increasing the FSH dose by 150IU (39). However, the vast majority of RCT evaluating rLH have failed to show an improvement in clinical pregnancy when compared to rFSH alone (29, 30, 36, 37, 40, 41, 86-89, 91, 92, 95). The majority of these trials were underpowered to detect for small differences in pregnancy outcomes between the study arms.

The Use of rLH, HMG and hCG in Controlled Ovarian Stimulation for Assisted Reproductive Technologies 63

2. rLH decreases the amount of rFSH needed for ovarian stimulation

3. It is uncertain if the addition of rLH increases pregnancy outcomes in ART

trials investigating the ability of hCG to replace LH for ovarian stimulation.

days, and 1,250 IU in a single dose on cycle day two (100-103).

hCG and LH have a significant degree of structural homology and both act on the LH receptor. hCG has a 6-8 fold affinity for the LH receptor as compared to LH only. Glycosylation additions to hCG also give it a longer half-life than LH. This has resulted in

Two studies have reported the use of hCG in the early follicular phase of ovarian stimulation (100, 101). These trials and two case reports have used various dosing strategies to deliver the hCG, including 200 IU per day for four or seven days, 50 IU per day for 14

In one trial, the addition of hCG resulted in significantly greater highly quality embryos (85% versus 47%) and pregnancy rates (46% versus 31%) (100). Overall, there is a lack of randomized controlled data evaluating the use of hCG from the early follicular phase, but

hCG has been evaluated as a mid-to-late cycle supplement to rFSH stimulation cycles in six trials. The dose of hCG utilized was 200IU per day in five trials and 250IU in another (104- 109). All trials were initiated with rFSH only for stimulation with hCG added when the follicles were between 12-14mm in size. Five of the trials reported a significantly higher estradiol level on the day of hCG in patients randomized to receive hCG stimulation, with increases in estradiol ranging from 700-1500 pg/ml (104-107, 109). A study by Filicori *et al.* further demonstrated a significantly higher fertilization rate in patients receiving hCG versus rFSH only (74% versus 48%) (104). The remainder of the trials did not show any differences in outcomes with hCG with regards to fertilization, implantation, or pregnancy (105-107, 109). These RCT total 614 patients and demonstrate that the addition of hCG results in higher estradiol levels and at least comparable ART outcomes to rFSH stimulation

In a retrospective analysis, Van Horne *et al.* demonstrated that the addition of daily hCG (50-100 IU per day) to a rFSH only stimulation protocol resulted in a decrease in average FSH administration by 1000IU per patient and resulted in a cost savings of \$600 in a military healthcare facility (110). In a subsequent publication, this same group demonstrated that low dose hCG was effective at significantly improving implantation rates (54% vs. 19%) and live-birth rates (64% vs. 25%) in patients who had endogenous LH levels ≤ 0.5 IU/L, while it had no benefit in patients with LH levels >0.5 IU/L (58). A metaanalysis of over 1,000 patients has demonstrated that the addition of hCG to ovarian

**4.1. Summary points**

1. rLH increases serum estradiol

what data is available is promising.

only.

**5. Human chorionic gonadotropin:** 

Four meta-analyses have been done to compare the outcomes of RCTs evaluating the use of rLH in ovarian stimulation (96-99). Kolibianakis *et al.* demonstrated no difference in live birth with the use of rLH, including in sub-analysis of early and mid-follicular administration or GnRH antagonist and agonist administration (97). Baruffi *et al.* did demonstrated a higher serum estradiol on the day of hCG (+514 pg/ml) and a higher number of MII oocytes retrieved (+0.88) with the use or rLH, but these differences did not translate into improve clinical pregnancy (96). In the largest meta-analysis, Mochtar *et al.*  demonstrated a trend towards improved live birth with rLH, but the result did not reach statistical significance (OR 1.22, 95%CI 0.95-1.56) (98). However, pooled analysis did show an improvement in live birth for poor responders who were stimulated with rLH (OR 1.85, 95% CI1.10-3.11) (98). rLH was shown to have increased estradiol, fewer days of stimulation, and lower FSH administration in a fourth meta-analysis, although once again no improvement in pregnancy outcomes was demonstrated (99).


**Table 2.** Meta-analyses comparing rLH plus rFSH versus rFSH only.

The data from the RCT and meta-analyses evaluating rLH is similar to that of hMG in showing a reduction in the amount of FSH required for stimulation and an increase in serum estradiol. However, these data differ in that they do not show a convincing increase in pregnancy outcomes. It is possible that this is due to the smaller numbers in the rLH meta-analysis. Only the Mochtar *et al.* paper had a power similar to that of the hMG metaanalysis to detect for live birth as an outcome. The heterogeneity within the design and results of the rLH studies themselves also is associated with a decreased power to detect for pregnancy outcomes and a wide confidence interval. It is also possible that the differences seen in the meta-analyses between rLH and hMG is not only statistical, but also due to the differences in the pharmaceuticals themselves. Differences in the glycosylation of LH between urinary and recombinant preparations and the addition of hCG to urinary preparations may lead to fundamental differences in biologic action which affect clinical results.
