Clinical pharmacology of recombinant human luteinizing hormone: Part II. Bioavailability of recombinant human luteinizing hormone assessed with an immunoassay and an in vitro bioassay

Analytical Investigation of the Profile of Human Chorionic Gonadotropin in Highly Purified Human Menopausal Gonadotrophin Preparations

Highly purified human menopausal gonadotropin (HP-hMG [Menopur®, Ferring Pharmaceuticals, Saint-Prex, Switzerland]) contains a 1:1 ratio of follicle-stimulating hormone (FSH) and luteinizing hormone (LH). This analysis aimed to assess gonadotropin (FSH, LH and hCG) abundance in HP-hMG and clarify the source of hCG by assessing the presence of sulfated glycans, which are diagnostic for pituitary hCG forms due to their distinct glycosylation patterns. Additionally, the purity of each sample, their specific components, and their oxidation levels were assessed. HP-hMG samples (three of Menopur® and two of Menogon® Ferring Pharmaceuticals, Saint-Prex, Switzerland) were included in the current analyses. Brevactid® (urinary hCG; Ferring Pharmaceuticals, Saint-Prex, Switzerland) and Ovidrel® (recombinant hCG; Merck KGaA, Darmstadt, Germany) were used as control samples. Glycopeptide mapping and analysis of impurities were carried out by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Oxidation was assessed through reducing peptide mapping using LC-MS/MS. The FSH and LH in the HP-hMG samples showed sulfated glycans, while no signals of sulfated glycopeptides were detected on any site of the beta subunit of hCG. HP-hMG test samples presented the same hCG glycan distribution as the control sample (placental hCG, Brevactid®) extracted from the urine of pregnant women, suggesting a non-pituitary source of hCG. Protein impurities were estimated to constitute approximately 20-30% of the entire HP-hMG protein content in the test samples. More than 200 non-gonadotropin proteins were identified in the HP-hMG test samples, of which several were involved in embryonic development or pregnancy. The alpha subunit of the tested samples was strongly oxidized, with a relative abundance of 20% of the total gonadotropin content. Without taking into account all the protein impurities, the beta subunit of LH was detected only in traces (0.9-1.2%) in all tested HP-HMG samples, confirming the data obtained by intact molecule analysis, while high levels of beta hCG (18-47%) were observed. Advanced molecular analysis of HP-hMG indicates a primarily placental origin of hCG, as evidenced by the absence of hCG sulfated glycans and the predominance of placental non-sulfated hCG in LH activity. The analysis revealed 20-30% of protein impurities and a significant presence of oxidized forms in the HP-hMG samples. These findings are critical for understanding the quality, safety, and clinical profile of HP-hMG.

Comparative Analysis of Commercial Immunoassays for the Determination of Total, Intact, and Nonintact Luteinizing Hormone in Urine

BACKGROUND

In our recent publications, we reported the identification of three different molecular forms of total luteinizing hormone (LH) in urine, the intact LH, the free beta-subunit (LHβ), and its core fragment of LHβ (LHβcf), the latter two establishing the nonintact portion of LH. Following the discontinuation of the Delfia immunofluorometric assay (IFMA) (Wallac, PerkinElmer Finland, Finland), a leading method for detecting urinary LH for 30 years, this study seeks to assess the efficacy of three alternative commercial immunoassays in identifying various forms of U-LH.

METHODS

Diluted urine samples underwent gel filtration to separate them into fractions, each containing different forms of LH. These were then assayed using Delfia IFMA, Architect LH (Abbott, USA), Elecsys LH Cobas (Roche, Switzerland), and Immulite 2000 LH (Siemens, Germany) immunoassays.

RESULTS

Both Delfia and Immulite assays detected total U-LH, that is, all three forms of U-LH, including intact LH, LHβ, and LHβcf. Cobas detected only intact LH and LHβ, whereas Architect detected solely the intact LH.

CONCLUSIONS

Immulite assay can be an alternative tool to detect all forms of urinary LH, a feature likely to be instrumental in developing noninvasive, practical, and scalable solutions for evaluating total U-LH changes during minipuberty in neonates, during the onset of central puberty in peripubertal children, puberty-associated disorders in adolescents, and the fertility window in women, with a special focus on postpeak changes.

Urine Sampling Protocol Recommendations for Reliable Determination of Total Urinary Luteinizing Hormone Immunoreactivity in the Pediatric Population

This study investigates day-to-day variations in urinary luteinizing hormone (U-LH) concentrations in children, focusing on potential minimization or correction methods. 95 children and adolescents (51 boys, 44 girls, ages 5-17) provided daytime and evening urine samples for U-LH determinations over three consecutive days. No consistent day-to-day differences in U-LH levels were observed, although random variations, particularly in adolescents aged 13 or older, were noted. The net inter-assay CV% for U-LH changes over three days showed high variability, averaging 24.6% to 28.0% for boys and 21.6% to 27.3% for girls, independent of sex, collection time, or U-LH level. To reliably determine total urinary luteinizing hormone immunoreactivity in the pediatric population, it is advisable to collect multiple first-morning voided samples for at least three consecutive days as an interim solution, pending the development of a standardized protocol or correction method for varying urine composition. Strict adherence, especially for adolescents aged 13 or older, is vital.

Novel Concepts for Inducing Final Oocyte Maturation in In Vitro Fertilization Treatment

Infertility affects one in six of the population and increasingly couples require treatment with assisted reproductive techniques. In vitro fertilization (IVF) treatment is most commonly conducted using exogenous FSH to induce follicular growth and human chorionic gonadotropin (hCG) to induce final oocyte maturation. However, hCG may cause the potentially life-threatening iatrogenic complication "ovarian hyperstimulation syndrome" (OHSS), which can cause considerable morbidity and, rarely, even mortality in otherwise healthy women. The use of GnRH agonists (GnRHas) has been pioneered during the last two decades to provide a safer option to induce final oocyte maturation. More recently, the neuropeptide kisspeptin, a hypothalamic regulator of GnRH release, has been investigated as a novel inductor of oocyte maturation. The hormonal stimulus used to induce oocyte maturation has a major impact on the success (retrieval of oocytes and chance of implantation) and safety (risk of OHSS) of IVF treatment. This review aims to appraise experimental and clinical data of hormonal approaches used to induce final oocyte maturation by hCG, GnRHa, both GnRHa and hCG administered in combination, recombinant LH, or kisspeptin. We also examine evidence for the timing of administration of the inductor of final oocyte maturation in relationship to parameters of follicular growth and the subsequent interval to oocyte retrieval. In summary, we review data on the efficacy and safety of the major hormonal approaches used to induce final oocyte maturation in clinical practice, as well as some novel approaches that may offer fresh alternatives in future.

Human Chorionic Gonadotropin: The Pregnancy Hormone and More

To thoroughly review the uses of human chorionic gonadotropin (hCG) related to the process of reproduction and also assess new, non-traditional theories. Review of the international literature and research studies. hCG and its receptor, LH/CGR, are expressed in numerous sites of the reproductive tract, both in gonadal and extra-goanadal tissues, promoting oocyte maturation, fertilization, implantation and early embryo development. Moreover, hCG seems to have a potential role as an anti-rejection agent in solid organ transplantation. Future research needs to focus extensively on the functions of hCG and its receptor LH/CGR, in an effort to reveal known, as well as unknown clinical potentials.

Pharmacokinetics of Lidocaine Hydrochloride Administered with or without Adrenaline for the Paravertebral Brachial Plexus Block in Dogs

Adrenaline is known to prolong the duration of local anesthesia but its effects on the pharmacokinetic processes of local anesthetic drugs are not fully understood. Our objective was to develop a compartmental model for quantification of adrenaline’s impact on the pharmacokinetics of perineurally-injected lidocaine in the dog. Dogs were subjected to paravertebral brachial plexus block using lidocaine alone or adrenalinated lidocaine. Data was collected through a prospective, randomised, blinded crossover protocol performed over three periods. Blood samples were collected during 180 minutes following block execution. Compartmental pharmacokinetic models were developed and their goodness-of-fit were compared. The lowering effects of adrenaline on the absorption of lidocaine were statistically determined with one-sided tests. A one-compartment disposition model with two successive zero-order absorption processes best fitted our experimental data. Adrenaline decreased the peak plasma lidocaine concentration by approximately 60% (P < 0.001), decreased this local anesthetic’s fast and slow zero-order absorption rates respectively by 50% and 90% (P = 0.046, and P < 0.001), which respective durations were prolonged by 90% and 1300% (P < 0.020 and P < 0.001). Lidocaine demonstrated a previously unreported atypical absorption profile following its paravertebral injection in dogs. Adrenaline decreased the absorption rate of lidocaine and prolonged the duration of its absorption.

Clinical Applications of Gonadotropins in the Male

The pituitary gonadotropins, luteinizing hormone (LH), and follicle-stimulating hormone (FSH) play a pivotal role in reproduction. The synthesis and secretion of gonadotropins are regulated by complex interactions among several endocrine, paracrine, and autocrine factors of diverse chemical structure. In men, LH regulates the synthesis of androgens by the Leydig cells, whereas FSH promotes Sertoli cell function and thereby influences spermatogenesis. Gonadotropins are complex molecules composed of two subunits, the α- and β-subunit, that are noncovalently associated. Gonadotropins are decorated with glycans that regulate several functions of the protein including folding, heterodimerization, stability, transport, conformational maturation, efficiency of heterodimer secretion, metabolic fate, interaction with their cognate receptor, and selective activation of signaling pathways. A number of congenital and acquired abnormalities lead to gonadotropin deficiency and hypogonadotropic hypogonadism, a condition amenable to treatment with exogenous gonadotropins. Several natural and recombinant preparations of gonadotropins are currently available for therapeutic purposes. The difference between natural and the currently available recombinant preparations (which are massively produced in Chinese hamster ovary cells for commercial purposes) mainly lies in the abundance of some of the carbohydrates that conform the complex glycans attached to the protein core. Whereas administration of exogenous gonadotropins in patients with isolated congenital hypogonadotropic hypogonadism is a well recognized therapeutic approach, their role in treating men with normogonadotropic idiopathic infertility is still controversial. This chapter concentrates on the main structural and functional features of the gonadotropin hormones and how basic concepts have been translated into the clinical arena to guide therapy for gonadotropin deficit in males.

A review of luteinising hormone and human chorionic gonadotropin when used in assisted reproductive technology

Gonadotropins extracted from the urine of post-menopausal women have traditionally been used to stimulate folliculogenesis in the treatment of infertility and in assisted reproductive technology (ART). Products, such as human menopausal gonadotropin (hMG), consist not only of a mixture of the hormones, follicle-stimulating hormone (FSH), luteinising hormone (LH) and human chorionic gonadotropin (hCG), but also other biologically active contaminants, such as growth factors, binding proteins and prion proteins. The actual amount of molecular LH in hMG preparations varies considerably due to the purification process, thus hCG, mimicking LH action, is added to standardise the product. However, unlike LH, hCG plays a different role during the natural human menstrual cycle. It is secreted by the embryo and placenta, and its main role is to support implantation and pregnancy. More recently, recombinant gonadotropins (r-hFSH and r-hLH) have become available for ART therapies. Recombinant LH contains only LH molecules. In the field of reproduction there has been controversy in recent years over whether r-hLH or hCG should be used for ART. This review examines the existing evidence for molecular and functional differences between LH and hCG and assesses the clinical implications of hCG-supplemented urinary therapy compared with recombinant therapies used for ART.

Luteinizing hormone and human chorionic gonadotropin: origins of difference

Luteinizing hormone (LH) and human chorionic gonadotropin (hCG) are widely recognized for their roles in ovulation and the support of early pregnancy. Aside from the timing of expression, however, the differences between LH and hCG have largely been overlooked in the clinical realm because of their similar molecular structures and shared receptor. With technologic advancements, including the development of highly purified and recombinant gonadotropins, researchers now appreciate that these hormones are not as interchangeable as once believed. Although they bind to a common receptor, emerging evidence suggests that LH and hCG have disparate effects on downstream signaling cascades. Increased understanding of the inherent differences between LH and hCG will foster more effective diagnostic and prognostic assays for use in a variety of clinical contexts and support the individualization of treatment strategies for conditions such as infertility.

Outcome from consecutive ICSI cycles in patients treated with recombinant human LH and those supplemented with urinary hCG-based LH activity during controlled ovarian stimulation in the long GnRH-agonist protocol

Clinical results were compared in a well-established, assisted reproduction program during the cross-over from highly purified (HP)-human menopausal gonadotropin (hMG) to rhFSH/rhLH. We included the last 33 patients treated with HP-hMG and the first 33 patients receiving rhFSH/rhLH for ovarian stimulation in their first intracytoplasmic sperm injection cycle. Patient baseline characteristics were almost identical in the two groups. Ovarian stimulation characteristics (days of stimulation, total amount of FSH administered using a modest initial loading dose of 150 IU/d, patients with oocyte retrieval) were similar for the two groups. However, the number of total and leading follicles and E2 serum levels on the human chorionic gonadotropin injection day were significantly higher in the rhFSH/rhLH group. The oocyte yield was significantly higher in the rhFSH/rhLH group as well as the number of metaphase II oocytes, difference almost reaching the statistical significance. The number of oocytes fertilized was also higher in patients receiving rhFSH/rhLH treatment. Implantation and clinical pregnancy rates were similar in both the study groups. It is concluded that in women undergoing controlled ovarian hyperstimulation under pituitary suppression for ART, the recombinant combined product containing FSH and LH in a fixed 2:1 ratio is more effective than HP-hMG in terms of follicle development, oocyte yield and quality, and fertilization rates.

Does exogenous LH in ovarian stimulation improve assisted reproduction success? An appraisal of the literature

A review of the scientific literature on the use of exogenous LH in assisted reproductive technology was performed by searching the MEDLINE, PubMed and Cochrane online databases. Scientific evidence was reviewed comparing recombinant FSH-only protocols to protocols supplemented with exogenous LH activity: human menopausal gonadotrophin (HMG), recombinant LH and mid-follicular human chorionic gonadotrophin (HCG). Studies were further compared based on pituitary suppression with gonadotrophin- releasing hormone (GnRH) antagonist and agonist protocols. Primary focus was given to randomized controlled trials and meta-analyses. Data from hypogonadotrophic hypogonadal patients demonstrated the importance of LH activity for success of assisted reproduction treatment. However, the majority of normogonadotrophic patients had adequate endogenous LH to successfully drive ovarian steroidogenesis and oocyte maturation. Exogenous LH supplementation was consistently associated with higher peak oestradiol concentrations. The use of HMG in long GnRH agonist cycles was associated with a 3–4% increase in live birth rate. There was insufficient evidence to make definitive conclusions on the need for exogenous LH activity in GnRH antagonist cycles or the benefit of recombinant LH and HCG protocols. Poor responders and patients 35 years of age and older may benefit from exogenous LH.

Who needs LH in ovarian stimulation?

LH plays a key role in the intermediate-late phases of folliculogenesis. Although ovarian stimulation is efficiently achieved in most cases by the administration of exogenous FSH alone, specific subgroups of women may benefit from LH activity supplementation during ovarian stimulation. Some authors have found improved outcome with LH activity supplementation in advanced reproductive age women. Experience suggests that in about 10-12% of young normogonadotrophic patients treated with a gonadotrophin-releasing hormone agonist (GnRH-a) long protocol plus recombinant FSH human (r-hFSH), a 'steady response' is observed. In this subgroup of women, a higher number of oocytes is retrieved when daily LH activity supplementation is given from stimulation day 8, if compared with the standard FSH dose increase. Another subgroup of patients who may benefit from LH activity supplementation are those at risk for poor ovarian response treated with GnRH antagonist. Recent data demonstrate that in these women, when GnRH is administered in a flexible protocol, the concomitant addition of recombinant human LH improves the number of mature oocytes retrieved, when compared with the standard GnRH-a flare-up protocol. Thus, well calibrated LH administration improves the ovarian outcome in patients >35 years, in those showing an initial abnormal ovarian response to r-hFSH monotherapy, and in 'low prognosis' women treated with GnRH antagonists.

Glycosylation of therapeutic proteins: an effective strategy to optimize efficacy

During their development and administration, protein-based drugs routinely display suboptimal therapeutic efficacies due to their poor physicochemical and pharmacological properties. These innate liabilities have driven the development of molecular strategies to improve the therapeutic behavior of protein drugs. Among the currently developed approaches, glycoengineering is one of the most promising, because it has been shown to simultaneously afford improvements in most of the parameters necessary for optimization of in vivo efficacy while allowing for targeting to the desired site of action. These include increased in vitro and in vivo molecular stability (due to reduced oxidation, cross-linking, pH-, chemical-, heating-, and freezing-induced unfolding/denaturation, precipitation, kinetic inactivation, and aggregation), as well as modulated pharmacodynamic responses (due to altered potencies from diminished in vitro enzymatic activities and altered receptor binding affinities) and improved pharmacokinetic profiles (due to altered absorption and distribution behaviors, longer circulation lifetimes, and decreased clearance rates). This article provides an account of the effects that glycosylation has on the therapeutic efficacy of protein drugs and describes the current understanding of the mechanisms by which glycosylation leads to such effects.

Effects of recombinant human LH and hCG on serum and urine LH and androgens in men

CONTEXT

The administration of gonadotrophins is prohibited in sport but the effect in men of recently available recombinant hCG and LH on serum and urine concentrations of gonadotrophins and androgens has not been systematically evaluated in the antidoping context.

OBJECTIVE

To determine the time-course of recombinant LH (rhLH) and hCG (rhCG) on blood and urine hormone profiles in men to develop effective tests to detect rhLH and rhCG doping.

DESIGN

Two randomized controlled studies with a 2 x 2 factorial design.

SETTING

Academic research centre.

PARTICIPANTS

Healthy male volunteers aged 18-45 years.

INTERVENTIONS

In the rhLH study, men were randomized into (i) either of two single doses of rhLH (75 IU or 225 IU), and (ii) suppression of endogenous LH and testosterone by nandrolone or no suppression. In the rhCG study, men were randomized into (i) either of two single doses of rhCG (250 or 750 microg), and (ii) suppression of endogenous LH and testosterone by nandrolone decanoate (ND) or no suppression. ND suppression comprised a single dose of 200 mg ND 3 days prior to, and in the rhCG study an additional dose 1 day after gonadotrophin injection.

MAIN OUTCOME MEASURES

Serum and urine hCG, LH, T, T : LH ratio, urine epitestosterone (E) and urine T : E ratio.

RESULTS

Neither rhLH dose produced a significant increase in serum or urine LH or T or in the T : E or T : LH ratios regardless of ND-induced suppression of endogenous LH and T. Nor did an even higher dose (750 IU) in three healthy men with unsuppressed gonadal axis. These findings were confirmed with two different commercial LH immunoassays together with adjustment for any influence of urine sediment and dilution. Both rhCG doses produced a steep, dose-proportional increase in serum and urine hCG with increases in serum and urine T and suppression of serum and urine LH, regardless of hCG dose. Serum but not urine T was lowered by ND suppression. The T : LH ratio showed a progressive increase unrelated to rhCG dose or ND suppression, whereas both rhCG and ND suppression minimally increased T : E ratio.

CONCLUSIONS

Both rhCG doses produce a striking increase in serum hCG and T with suppression of serum LH but, at single doses up to 750 IU, rhLH has no influence on serum or urine LH or T. Effective rhLH doping, which relies on a sustained increases in endogenous T, would require much higher and more frequent daily rhLH doses. Use of LH immunoassays optimized for serum to detect rhLH doping by urine LH measurement requires more standardization and validation and, at present, is unreliable. The T : LH ratio is, however, a useful screening test for hCG doping although its utility requires further evaluation.

Drug delivery for in vitro fertilization: rationale, current strategies and challenges

In vitro fertilization has experienced phenomenal progress in the last thirty years and awaits the additional refinement and enhancement of medication delivery systems. Opportunity exists for the novel delivery of gonadotropins, progesterone and other adjuvants. This review highlights the rationale for various medications, present delivery methods and introduces the status of novel ideas and possibilities.

Administration of follitropin alfa and lutropin alfa combined in a single injection: a feasibility assessment

BACKGROUND

Gonadotrophins are routinely administered in assisted reproductive technology (ART) treatment protocols. Recombinant human follicle-stimulating hormone (r-hFSH; follitropin alfa) and recombinant human luteinizing hormone (r-hLH; lutropin alfa) can be administered individually or in a fixed combination. The ability to vary the FSH to LH dose ratio in a single injection without compromising the bioactivity of either gonadotrophin or generating losses of active principle is important for physicians and patients alike.

METHODS

This study investigated whether follitropin alfa (GONAL-f ), as lyophilized powder for reconstitution or solution from the GONAL-f (filled-by-mass [FbM]) Prefilled Pen, could be used to reconstitute Pergoveris TM (follitropin alfa/lutropin alfa 150 IU/75 IU) lyophilized powder. In Ratio Groups 1 and 2, the r-hFSH:r-hLH ratio was 3:1; in Ratio Groups 3 and 4, the ratios of r-hFSH:r-hLH were 5:1 and 8:1, respectively. The protein content and bioactivity of each mixed solution were evaluated. The r-hFSH and r-hLH content was determined using reverse-phase high performance liquid chromatography. The biological activity of r-hFSH and r-hLH was assessed using the Steelman-Pohley and Van Hell in vivo bioassays in rats, respectively.

RESULTS

Follitropin alfa/lutropin alfa 150 IU/75 IU lyophilized powder could be successfully mixed with follitropin alfa 75 IU FbM solution that was either reconstituted from lyophilized powder or injected directly from the prefilled pen to create solutions with ratios of r-hFSH and r-hLH from 3:1 to 8:1. The measured content of r-hFSH and r-hLH corresponded favourably with the target protein content in Ratio Groups 1-4. The in vivo target and measured bioactivity of r-hFSH and r-hLH were also closely matched in all Ratio Groups.

CONCLUSION

Follitropin alfa lyophilized powder or solution can be accurately mixed with follitropin alfa/lutropin alfa 150 IU/75 IU lyophilized powder to enable physicians to administer ratios of r-hFSH and r-hLH in the IU range from 3:1 to 8:1. Mixing of recombinant formulations offers flexibility for patients receiving follitropin alfa and lutropin alfa for ART protocols in clinical practice.

Lutropin alfa

Lutropin alfa is the first and only recombinant human form of luteinizing hormone (LH) developed for use in the stimulation of follicular development. Dose-finding studies revealed a significant dose-dependent increase in the rate of optimal follicular development among women with hypogonadotropic hypogonadism and profound LH deficiency (<1.2 IU/L) who received subcutaneous lutropin alfa 0-225 IU/day plus follitropin alfa. Similarly, in a double-blind, randomized study, the rate of optimal follicular development was significantly higher in women with hypogonadotropic hypogonadism and profound LH deficiency receiving subcutaneous lutropin alfa 75 IU/day plus follitropin alfa than in those receiving placebo plus follitropin alfa. Lutropin alfa with follitropin alfa may also be of benefit in certain subgroups of normogonadotropic women (e.g. those with an inadequate response to prior follitropin alfa monotherapy, those aged >or=35 years, and those with profound LH downregulation or who required excessive exogenous follitropin alfa). However, one study in older women (>or=35 years) did not show any advantage of lutropin alfa supplementation. Once-daily subcutaneous lutropin alfa was generally well tolerated in hypogonadotropic hypogonadal women, with the majority of adverse events being of mild to moderate severity.

New insights into the evolution of chorionic gonadotrophin

The glycoprotein hormones luteinizing hormone (LH) and chorionic gonadotrophin (CG) are crucial for reproduction, as LH induces sex hormone production and ovulation, and CG is essential for the establishment of pregnancy and fetal male sexual differentiation. Both consist of two heterodimeric peptides of which the alpha-subunit is common to both hormones whereas the beta-subunit is hormone-specific. The CGB gene was derived from LHB by gene duplication and frame shift mutation that led to a read-through into the formerly 3'-untranslated region, giving rise to the carboxyl-terminal peptide. Owing to nucleotide changes within the 5'-region of CGB, a new transcriptional start site and regulatory region was gained. These changes led to the specific expression of CGB in the placenta and its decrease in the pituitary. Recent findings on gonadotrophins led to an extended model for the sequence of events in the evolution of the CGB gene in primates and its tissue-specific expression.

Exploiting LH in ovarian stimulation

During intermediate-late phases of human folliculogenesis, LH plays a key role in promoting steroidogenesis and growth of the leading follicle. Ovarian stimulation for assisted reproduction techniques usually consists of administering exogenous FSH in a low LH environment. Although an impairment in LH-dependent paracrine activities would be expected, multiple follicular growth is efficiently achieved in almost all patients. Thus, there appears to be a discrepancy between classical folliculogenesis models and data from IVF. This study examines the 'interface' between basic endocrinological and clinical evidence, in an attempt to answer two questions: is there an LH therapeutic window, and if there is, how can this be exploited in the practice of assisted reproduction? It also reviews the evidence that specific subgroups of women may benefit from LH supplementation during ovarian stimulation.

Who needs LH in ovarian stimulation?

LH plays a key role in the intermediate-late phases of folliculogenesis. Although ovarian stimulation is efficiently achieved in most cases by the administration of exogenous FSH alone, specific subgroups of women may benefit from LH activity supplementation during ovarian stimulation. Some authors have found improved outcome with LH activity supplementation in advanced reproductive age women. Experience suggests that in about 10-12% of young normogonadotrophic patients treated with a gonadotrophin-releasing hormone agonist (GnRH-a) long protocol plus recombinant FSH human (r-hFSH), a 'steady response' is observed. In this subgroup of women, a higher number of oocytes is retrieved when daily LH activity supplementation is given from stimulation day 8, if compared with the standard FSH dose increase. Another subgroup of patients who may benefit from LH activity supplementation are those at risk for poor ovarian response treated with GnRH antagonist. Recent data demonstrate that in these women, when GnRH is administered in a flexible protocol, the concomitant addition of recombinant human LH improves the number of mature oocytes retrieved, when compared with the standard GnRH-a flare-up protocol. Thus, well calibrated LH administration improves the ovarian outcome in patients >35 years, in those showing an initial abnormal ovarian response to r-hFSH monotherapy, and in 'low prognosis' women treated with GnRH antagonists.

Biochemical and functional aspects of gonadotrophin-releasing hormone and gonadotrophins

Reproductive function in mammals is governed by the hypothalamic-pituitary-gonadal axis, which conforms a functional unit. Sexual maturation and the subsequent development of reproductive competence depend on the precise and coordinated function of this axis. The components of the reproductive axis communicate each other through endocrine signals. The hypothalamus synthesizes gonadotrophin-releasing hormone or GnRH, which in turn stimulates synthesis and secretion of the pituitary gonadotrophins, follicle-stimulating hormone (FSH) and luteinizing hormone (LH). The ovarian follicles and the interstitial and Sertoli cells of the testis are the targets for these pituitary signals. Under gonadotrophic stimulation, the gonads produce and secrete several steroid and non-steroid (polypeptide) factors, which in turn regulate in different ways the function of the hypothalamic-pituitary axis. An episodic and pulsatile mode of secretion of hormonal signals characterize (as in other endocrine systems) the function of the reproductive axis, particularly that of the hypothalamic-pituitary unit. The target cell response, and consequently the harmonic function of the corresponding gland, will depend on the adequate dynamics of this pulsatile secretion. The function of each component of the reproductive axis is strongly influenced by locally-produced signals acting either in a paracrine or autocrine manner; these particular signals represent fine-tuning regulation systems that eventually amplify or restrain the magnitude of response to a particular endocrine signal, providing additional mechanisms for tissue homeostasis and a better functional plasticity of the target gland. The design and rational use of novel therapeutic strategies for an optimal exogenously-controlled reproductive function largely depend on the detailed knowledge of the hypothalamic-pituitary-gonadal axis function and the structure and mechanism of action of those factors and signals involved in its regulation.

Hemodynamic changes induced by urinary human chorionic gonadotropin and recombinant luteinizing hormone used for inducing final follicular maturation and luteinization

OBJECTIVE

To compare the safety of recombinant human luteinizing hormone (LH) with that of urinary hCG in terms of the hemodynamic changes when they are used to induce final follicular maturation in patients undergoing in vitro fertilization (IVF). A secondary end point was efficacy in terms of IVF outcome.

DESIGN

Prospective, randomized clinical trial.

SETTING

University teaching hospital.

PATIENT(S)

Thirty IVF patients.

INTERVENTION(S)

Ovarian stimulation was induced with FSH under pituitary suppression. Patients were randomized to receive either hCG or recombinant human LH as a trigger of oocyte maturation (5,000 IU) and for luteal phase support (5,000 IU, 2,500 IU, and 2,500 IU on the day of follicular aspiration, 2 days later, and 5 days later, respectively).

MAIN OUTCOME MEASURE(S)

Mean arterial pressure, cardiac output, peripheral vascular resistance, and serum levels of progesterone, plasma concentrations of aldosterone, norepinephrine, and plasma renin activity were measured in all patients on postovulatory day 7 of the spontaneous menstrual cycle preceding IVF (baseline) and 7 days after the hCG/recombinant human LH ovulatory injection during the IVF cycle.

RESULT(S)

Ovarian response and IVF outcome (pregnancy rate, 60%) were similar in both treatment groups. On the seventh day after hCG/recombinant human LH administration, the peripheral vascular resistance was significantly lower and serum progesterone concentrations significantly higher in the hCG group as compared with the recombinant human LH group. The percentage change from baseline values during IVF cycles in all hemodynamic and neurohormonal variables investigated was higher (albeit not statistically different) in the group treated with hCG vs. the group treated with recombinant human LH.

CONCLUSION(S)

Recombinant human LH is associated with less intense circulatory changes than hCG when it is given to induce final follicular maturation and luteal phase support in IVF procedures.

[Ovarian stimulation: is exogenous LH necessary in all patients?]

FSH and LH play an essential but different role in the growth of ovarian follicles during the cycle. In stimulation protocols, good follicular development is obtained in most patients treated with FSH alone whereas the role of LH is more complex and controversial. Clinical and pre-clinical studies have shown that optimal follicular development is obtain if (i) exposure to endogenous and/or exogenous LH is sufficient ("threshold" concept) and (ii) exposure to LH is not excessive ("ceiling" concept). The recombinant luteinizing hormone (r-hLH, Luveris) is the only available stand-alone preparation of LH. Its characteristics are a high specific activity, the absence of undesirable proteins and an excellent batch to batch consistency. Luveris is indicated in association with FSH for stimulating follicular development in LH and FSH deficient women (defined by an endogenous LH level < 1.2 UI/l). In this subgroup of patients, the therapeutic benefit of exogenous LH at a daily dose of 75 IU is only observed when endogenous serum LH is below than 1.2 IU/l: LH threshold concept. In ART, the combination of exogenous LH at a daily dose from 75 to 150 IU and recombinant FSH improved the ovarian stimulation results only in a minority of patients (5 to 17%). On the opposite, studies conducted in OMS I and II patients showed that high doses of exogenous LH lead to atresia of secondary follicles. So, a daily dose of exogenous LH greater than 225 IU had a deleterious effect on follicular growth: LH ceiling concept.

The effectiveness and safety of recombinant human LH to support follicular development induced by recombinant human FSH in WHO group I anovulation: evidence from a multicentre study in Spain

BACKGROUND

Until recently, human menopausal gonadotrophin (HMG), a urinary extract containing a fixed combination of LH and FSH, was the only source of exogenous LH for women with hypogonadotrophic hypogonadism undergoing ovulation induction with gonadotrophins. Recombinant human LH (rLH) is now available for clinical use, providing a new treatment option but clinical data on its use are scanty. Therefore, the aim of the present study was to investigate the efficacy and safety of rLH combined with recombinant FSH (rFSH) to induce follicular development and ovulation in World Health Organization (WHO) group I anovulatory women.

METHODS

We included in this multicentre study 38 hypogonadotrophic anovulatory (WHO group I) women. Patients received 150 IU/day rFSH and 75 IU/day rLH (with the possibility of dose adjustment) as a single s.c. injection for up to three cycles with a total of 84 treatment cycles.

RESULTS

Sufficient follicular growth was observed in 79 (94%) out of 84 initiated cycles. The 75 IU rLH dose was found to be effective in most treatment cycles (94%) and only five cycles in three patients required daily dose increase. Overall, HCG was administered to trigger ovulation in 67 (80%) of the 84 cycles while it was withheld in 12 cycles (14%) due to ovarian hyper-response and five cycles (6%) were cancelled for insufficient follicular growth. The pregnancy rate per started treatment cycle and per cycle given HCG was 18 and 22.4% respectively. Pregnancy was achieved by 15 (39.5%) of the 38 patients. Mild to moderate ovarian hyperstimulation syndrome occurred in three patients. Local tolerance was good.

CONCLUSIONS

This study confirms that combined rFSH and rLH treatment induces follicular growth, ovulation and pregnancy in a good proportion of hypogonadotrophic anovulatory patients and is well tolerated. The doses of 150 IU rFSH and 75 IU rLH daily seem the most appropriate but in a small minority of patients doses >75 IU rLH/day may be necessary.

Human recombinant luteinizing hormone is as effective as, but safer than, urinary human chorionic gonadotropin in inducing final follicular maturation and ovulation in in vitro fertilization procedures: results of a multicenter double-blind study

In a prospective, comparative, dose-finding study, the minimal effective dose of recombinant human LH (rhLH) required to induce final follicular maturation and early luteinization in patients undergoing in vitro fertilization and embryo transfer was determined. In addition, the efficacy and safety of rhLH were compared with urinary human CG (u-hCG). A total of 259 infertile women, aged 18-39 yr, were enrolled in the study. After pituitary desensitization using a GnRH agonist, rhFSH was administered for ovarian stimulation. Patients then received either rhLH or u-hCG to achieve final follicular maturation. The doses of rhLH administered were 5,000, 15,000, 30,000, or 15,000 + 10,000 IU (second injection administered 3 days after the first injection; 129 patients), and those of u-hCG were consistently 5,000 IU (121 patients). Ovum pick-up was performed 34--38 h after rhLH or u-hCG injection. After fertilization in vitro, up to three embryos were replaced in the uterine cavity. The numbers of oocytes retrieved after u-hCG or rhLH administration were not significantly different between the four different doses of rhLH, when compared with each corresponding u-hCG group, nor when compared with the pool of all u-hCG groups. Similarly, there were no statistically significant differences in: the number of oocytes retrieved per follicle with a diameter of over 10 mm on the day of u-hCG or rhLH administration; the number of patients with at least one oocyte retrieved; oocyte nuclear maturity; oocyte potential for fertilization; the number of embryos; the number of total, biochemical, and clinical pregnancies; and the embryo implantation rate. However, in many of these parameters, the lowest dose of rhLH seemed suboptimal when compared with the higher dose. In terms of safety, rhLH was well tolerated at a dose of up to 30,000 IU. Moderate ovarian hyperstimulation syndrome (OHSS) was reported in 12.4% of patients who received u-hCG and 12.0% of patients who received two injections of rhLH. No moderate or severe OHSS was reported in patients who received a single dose of rhLH up to 30,000 IU. The results show that a single dose of rhLH is effective in inducing final follicular maturation and early luteinization in in vitro fertilization and embryo transfer patients and is comparable with 5,000 IU u-hCG. A single dose of rhLH results in a highly significant reduction in OHSS compared with hCG. The dose of rhLH giving the highest efficacy to safety ratio was between 15,000 and 30,000 IU.

Effects of human recombinant luteinizing hormone and follicle-stimulating hormone in patients with acquired hypogonadotropic hypogonadism: study of Sertoli and Leydig cell secretions and interactions

Experimental data suggest that FSH-stimulated Sertoli cells can enhance LH-induced Leydig cell testosterone (T) production. The function of Leydig and Sertoli cells can be selectively studied by using recombinant human LH (rhLH) and recombinant human FSH (rhFSH) in patients with complete gonadotropin deficiency. The aim of the present study was to assess the secretion of testicular T, estradiol (E2), and inhibin B and the physiological relevance of the Sertoli-Leydig cell interaction in man. For that purpose, six patients with acquired complete hypogonadotropic hypogonadism received the following treatments for three periods of 1 month in a random order: 1) rhLH, 900 IU/day sc; 2) rhFSH, 150 IU/day sc; and 3) combined rhLH/rhFSH treatments. Each treatment period was separated by a washout period of 15 days. Plasma LH, FSH, T, E2, and inhibin B were measured before and every 10 days during each treatment. During rhLH administration, mean plasma LH levels rose significantly from 0.4 +/- 0.2 IU/L to 11.7 +/- 1.2 IU/L (P < 0.01) and plasma FSH levels did not change. rhFSH administration induced a significant increase in plasma FSH levels (from 0.5 +/- 0.4 to 12.1 +/- 1.4 IU/L; P < 0.01), whereas mean plasma LH levels remained low. Mean plasma E2 levels were unchanged during rhFSH treatment, but they increased significantly during rhLH from 22 +/- 4 to 54 +/- 8 pmol/L (P < 0.01) and during rhLH plus rhFSH administration. rhFSH treatment induced a sustained elevation of mean plasma inhibin B levels from 58 +/- 13 to 175 +/- 25 pg/mL (P < 0.01), similar to the increase occurring during rhFSH plus rhLH administration. In contrast, mean plasma inhibin B levels did not increase during rhLH administration. Finally, a similar and significant increase in mean plasma T levels occurred during both rhLH and rhLH plus rhFSH treatment from 0.9 +/- 0.3 to 5.4 +/- 0.7 nmol/L (P < 0.01) and from 1.0 +/- 0.4 to 6.0 +/- 0.9 nmol/L (P < 0.01), respectively. In contrast, during rhFSH treatment mean plasma T levels remained unchanged when compared with baseline.

IN CONCLUSION

1) the increase of plasma E2 induced by rhLH and the absence of effect of rhFSH confirm that Leydig cells are the major site of testicular E2 production in man; 2) the secretion of inhibin B is increased by rhFSH and not by rhLH, and, thus, Sertoli cells seem to be the main source of inhibin B production; and 3) the increase of plasma T induced by rhLH is not enhanced by rhFSH. These results suggest that the stimulatory effect of FSH on Leydig cell steroidogenesis by a Sertoli cell paracrine factor does not seem to play a major physiologic role in man.

The role of gonadotropins in follicular development and their use in ovulation induction protocols for assisted reproduction

During the 1960s, hypogonadotropic patients with polycystic ovary syndrome and those with clomiphene citrate resistance were the first to achieve pregnancy after urinary human menopausal gonadotropin (hMG) administration plus preovulatory human chorionic gonadotropin injection, with cumulative pregnancy rates ranging from 40% to 80% after six to 12 treatment cycles. Ever since, dramatically more progress has been achieved regarding methods and medication in assisted conception techniques, involving both a rapidly increased number of subfertile couples, as well as many practitioners in obstetrics and gynecology. The purpose of this review was to highlight the most crucial historical steps of this remarkable process, by emphasizing the role of gonadotropins in ovulation induction protocols according to the various clinical categories of subfertile patients. In the late 1970s, urinary hMG was the most widely used gonadotropin for ovarian stimulation during in vitro fertilization-embryo transfer for assisted reproduction. The often concurrent problems of premature luteinizing hormone (LH) surges and premature luteinizations, and thus cancellations of the cycles, were efficiently overcome by 'reversible medical hypophysectomy', performed by gonadotropin releasing hormone (GnRH) analogs, introduced in 1982. According to its initiation and duration, GnRH analog use was divided into three protocols: the long, most widely used, protocol, which was the best for suppression of endogenous, high tonic LH levels, especially in polycystic ovary syndrome and normogonadotropic patients; and the short and ultra-short protocols, which were mainly used in poor responders to ovarian stimulation treatment, older or hypergonadotropic patients with ovarian failure, because of the well-known 'flare-up phenomenon'. Recently, GnRH antagonists, which directly do not permit GnRH action by binding to the GnRH gonadotropic cell receptors, have been used, but no final results from large, multicenter clinical trials that are still being undertaken have yet been achieved. Various sub-products of urinary hMG have been produced since the 1980s, with the intention of eliminating most or all of the LH, such as a form with a 3:1 proportion ratio between follicle stimulating hormone (FSH) and LH, as well as a form resulting in the removal of almost all of the LH, the 'pure' urinary FSH. Finally, in the mid-1990s, recombinant pure FSH was produced in vitro from hamster ovarian cell cultures. The theoretical basis for the broad use of pure urinary FSH and recombinant FSH is that the very low endogenous LH levels after pituitary desensitization are sufficient for proper theca steroidogenesis; still, data in the literature and clinical experience may be controversial upon that issue. From the clinical point of view, clinicians nowadays tend to stimulate polycystic ovary syndrome patients with recombinant FSH plus the application of GnRH analogs in a long protocol. However, in poor responders, patients in whom ovulation is resistant to clomiphene citrate, those older than 40 years or hypergonadotropic patients with ovarian failure, urinary hMG, because endogenous LH levels are obviously not sufficient for proper steroidogenesis in the theca cells of the follicles of these patients, is necessary in add to the administration of GnRH analogs in a short or ultra-short protocol. Regarding normogonadotropic women (the majority of patients), most authors agree with the long-protocol application of GnRH analogs. In these patients, it is not certain whether recombinant FSH alone is sufficient for the best possible induction or whether exogenous LH administration in the form of urinary hMG still remains necessary.

Time-course effects of human recombinant luteinizing hormone on porcine Leydig cell specific differentiated functions

Since recombinant hormones are considered as safer and more reliable in their bioactivity than extractive hormones, the recently available human recombinant luteinizing hormone (r-hLH), will probably replace hCG in the near future, for clinical purposes. This prompted us to investigate whether or not, and by which mechanisms, r-hLH can induce a desensitization of signal transduction and/or an up-regulation of steroidogenic capacity in Leydig cells. The effects of a 30 min to 24 h exposure to r-hLH (10(-9) M) on the differentiated functions of cultured immature porcine Leydig cells were studied by measuring the following parameters: LH/hCG receptor number and mRNA, hCG-, cholera toxin- and forskolin-induced cAMP production, G protein alphas subunit content of the membrane, hCG-, cholera toxin-, forskolin-, 8Br-cAMP-, 22R-OH-cholesterol-, progesterone-, 170H-progesterone-, DHEA-, delta4-androstenedione-induced testosterone secretion and StAR, 3beta-HSD, cytochrome P-450scc and P-450c17 mRNAs. hCG binding sites and LH/hCG receptor mRNA were slowly down regulated by r-hLH, reaching 47+/-1 and 18+/-7% of control at 24 h, respectively. Down-regulation of both hCG- and cholera toxin-induced cAMP production occurred earlier and was more marked, and at 24 h represented only 2.7+/-0.5 and 12.5+/-3.6% of control. Due to the synergistic effect of r-hLH and forskolin on cAMP production, the forskolin-induced cAMP was higher in r-hLH treated than in control cells, but this response also declines with time and was, at 24 h, only 32% of that observed at 30 min. This decreased cAMP production was associated with a less marked decline in the amount of membrane content of Galphas protein. The testosterone production in response to hCG, cholera toxin, forskolin and 8Br-cAMP declined to reach a nadir at 6 h but increased thereafter and at 24 h was significantly higher than in control cells. In contrast, the conversion of several precursors into testosterone remained stable or increased slightly during the first hours of r-hLH treatment and significantly increased at 24 h and this was associated with an increase of StAR, 3beta-HSD, P-450scc and P-450c17 mRNAs. Taken together, the present results indicate that, despite the marked down-regulation of transmembrane signaling, r-hLH increased the steroidogenic capacity of Leydig cells by increasing the expression of several genes encoding the proteins involved in testosterone synthesis.

Pharmacokinetic and pharmacodynamic interactions between recombinant human luteinizing hormone and recombinant human follicle-stimulating hormone

OBJECTIVE

To assess the pharmacokinetics of a recombinant human LH preparation and its pharmacokinetic and pharmacodynamic interactions with recombinant human follicle-stimulating hormone (FSH).

DESIGN

Prospective, randomized cross-over study.

SETTING

Phase I clinical research environment.

PATIENT(S)

Twelve healthy pituitary down-regulated females.

INTERVENTION(S)

Subjects received 150 IU of s.c. recombinant human LH and FSH, either alone or in combination, followed by recombinant human LH and FSH once daily for 7 days.

MAIN OUTCOME MEASURE(S)

Pharmacokinetic parameters, ovarian follicle development.

RESULT(S)

No pharmacokinetic interaction between recombinant human LH and FSH was observed, with no significant difference in baseline-corrected maximal observed concentration over baseline, area under the concentration-time curve from t = 0 to t = 24 hours, or time to maximal concentration after single doses alone or in combination. After daily administration, the mean accumulation ratio was 1.6 for LH and 2.9 for FSH, with absorption and terminal phase half-life estimates of 4 and 11 hours for LH and 8 and 16 hours for FSH, respectively. Combined administration of FSH and LH for 7 days was effective in stimulating ovarian follicular development and steroidogenesis, with large interindividual variability related to ovarian sensitivity.

CONCLUSION(S)

A new recombinant human LH preparation has a low accumulation ratio at steady-state and no pharmacokinetic or pharmacodynamic interactions with recombinant human FSH.