Pharmacodynamics of a single low dose of long-acting recombinant follicle-stimulating hormone (FSH-carboxy terminal peptide, corifollitropin alfa) in women with World Health Organization group II anovulatory infertility

Undissociable chemically cross-linked and single-chain gonadotropins

Undissociable gonadotropins can be obtained either by chemical cross-linking of the natural heterodimeric hormones or by expressing recombinant single-chain molecules through the fusion of their α and β polypeptide sequences. These undissociable hormones are not more active than their natural heterodimeric counterparts indicating that the β-subunit seatbelt embracing the α-subunit ensures the αβ heterodimer stability in physiological conditions. The main interests of single-chain gonadotropins are that 1/only one single plasmid is required to produce an active recombinant hormone, 2/the two subunits' domains are constantly present in equal amounts and 3/they remain in close proximity even at low concentration for forming the hormone bioactive 3D structure. These undissociable gonadotropins have been shown to exhibit excellent stability and activity but they have not yet been commercialized probably because of immunogenicity risks and cost of production. Nevertheless, they might be used as a basis for the development of chemically simpler and cheaper ligands of LH and FSH receptors.

Discovery and Preclinical Development of Orally Active Small Molecules that Exhibit Highly Selective Follicle Stimulating Hormone Receptor Agonism

An orally active follicle stimulating hormone receptor allosteric agonist would provide a preferred treatment for over 16 million infertile women of reproductive age in low complexity methods (ovulation induction-intrauterine insemination) or in high complexity methods (controlled ovarian stimulation-in vitro fertilization). We present two oral follicle stimulating hormone receptor allosteric agonist compounds that have the desired pharmacology, drug metabolism, pharmacokinetics, and safety profile for clinical use. These molecules provide a single agent suitable for ovulation induction-intrauterine insemination or controlled ovarian stimulation-in vitro fertilization that is more convenient for patients and achieves similar preclinical efficacy as rec-hFSH. TOP5668, TOP5300 were evaluated in vitro in Chinese hamster ovary cells transfected with individual glycoprotein receptors measuring cAMP (FSHR, LH/CGR, thyroid stimulating hormone receptor). TOP5668 was found to have solely follicle stimulating hormone receptor allosteric agonist activity while TOP5300 was found to have mixed follicle stimulating hormone receptor allosteric agonist and LHR-AA activity. Both compounds stimulated concentration-dependent increases in estradiol production from cultured rat granulosa cells in the presence or absence of low dose rec-hFSH, while only TOP5300 stimulated testosterone production from rat primary Leydig cells. In pooled human granulosa cells obtained from patients undergoing controlled ovarian stimulation-in vitro fertilization, TOP5300 stimulated 7-fold greater maximal estradiol response than rec-hFSH and TOP5668 was 10-fold more potent than TOP5300. Both TOP5300 and TOP5668 stimulated follicular development in immature rat to the same efficacy as recombinant follicle stimulating hormone. In mice treated with TOP5300, in the presence of low dose of follicle stimulating hormone, there were no differences in oocyte number, fertilization rate, and hatched blastocyst rate in mice with TOP5300 and low dose follicle stimulating hormone vs. reference proteins pregnant mare serum gonadotropin or high dose rec-hFSH. ADME/PK and safety profiles were favorable. In addition, there was no appreciable activity on thyroid hormones by TOP5300 in 14-days toxicological study in rat or dog. The selected lead compound, TOP5300 stimulated a more robust increase in estradiol production from granulosa-lutein cells from women with polycystic ovarian syndrome patient compared to rec-hFSH. Conclusions: Two novel oral FSHR allosteric agonist, TOP5668 and TOP5300, were found to mimic the biological activity of rec hFSH in preclinical studies. Both compounds led to folliculogenesis and superovulation in rat and mice. Specifically, TOP5300 led to a similar number of ovulated oocytes that fertilized and developed into hatched blastocysts in mice when compared to rec-hFSH. The safety profile demonstrated lack of toxicity.

Allosteric Regulation of the Follicle-Stimulating Hormone Receptor

Follicle-stimulating hormone receptor (FSHR) belongs to the leucine-rich repeat family of the G protein-coupled receptor (LGR), which includes the glycoprotein hormone receptors luteinizing hormone receptor, thyrotropin receptor, and other LGRs 4, 5, 6, and 7. FSH is the key regulator of folliculogenesis in females and spermatogenesis in males. FSH elicits its physiological response through its cognate receptor on the cell surface. Binding of the hormone FSH to its receptor FSHR brings about conformational changes in the receptor that are transduced through the transmembrane domain to the intracellular region, where the downstream effector interaction takes place, leading to activation of the downstream signaling cascade. Identification of small molecules that could activate or antagonize FSHR provided interesting tools to study the signal transduction mechanism of the receptor. However, because of the nature of the ligand-receptor interaction of FSH-FSHR, which contains multiple sites in the extracellular binding domain, most of the small-molecule modulators of FSHR are unable to bind to the orthosteric site of the receptors. Rather they modulate receptor activation through allosteric sites in the transmembrane region. This review will discuss allosteric modulation of FSHR primarily through the discovery of small-molecule modulators, focusing on current data on the status of development and the utility of these as tools to better understand signaling mechanisms.

Efficacy of corifollitropin alfa followed by recombinant follicle-stimulating hormone in a gonadotropin-releasing hormone antagonist protocol for Korean women undergoing assisted reproduction

Objective

To evaluate the effect of a gonadotropin-releasing hormone (GnRH) antagonist protocol using corifollitropin alfa in women undergoing assisted reproduction.

Methods

Six hundred and eighty-six in vitro fertilization-embryo transfer (IVF)/intracytoplasmic sperm injection (ICSI) cycles were analyzed. In 113 cycles, folliculogenesis was induced with corifollitropin alfa and recombinant follicle stimulating hormone (rFSH), and premature luteinizing hormone (LH) surges were prevented with a GnRH antagonist. In the control group (573 cycles), premature LH surges were prevented with GnRH agonist injection from the midluteal phase of the preceding cycle, and ovarian stimulation was started with rFSH. The treatment duration, quality of oocytes and embryos, number of embryo transfer (ET) cancelled cycles, risk of ovarian hyperstimulation syndrome (OHSS), and the chemical pregnancy rate were evaluated in the two ovarian stimulation protocols.

Results

There were no significant differences in age and infertility factors between treatment groups. The treatment duration was shorter in the corifollitropin alfa group than in the control group. Although not statistically significant, the mean numbers of matured (86.8% vs. 85.1%) and fertilized oocytes (84.2% vs. 83.1%), good embryos (62.4% vs. 60.3%), and chemical pregnancy rates (47.2% vs. 46.8%) were slightly higher in the corifollitropin alfa group than in the control group. In contrast, rates of ET cancelled cycles and the OHSS risk were slightly lower in the corifollitropin alfa group (6.2% and 2.7%) than in the control group (8.2% and 3.5%), although these differences were also not statistically significant.

Conclusion

Although no significant differences were observed, the use of corifollitropin alfa seems to offer some advantages to patients because of its short treatment duration, safety, lower ET cancellation rate and reduced risk of OHSS.

Long-acting FSH versus daily FSH for women undergoing assisted reproduction

BACKGROUND

Assisted reproduction techniques (ART), such as in vitro fertilisation (IVF) and intracytoplasmic sperm injection (ICSI), can help subfertile couples to create a family. It is necessary to induce multiple follicles, which is achieved by follicle stimulating hormone (FSH) injections. Current treatment regimens prescribe daily injections of FSH (urinary FSH either with or without luteinizing hormone (LH) injections or recombinant FSH (rFSH)).Recombinant DNA technologies have produced a new recombinant molecule which is a long-acting FSH, named corifollitropin alfa (Elonva) or FSH-CTP. A single dose of long-acting FSH is able to keep the circulating FSH level above the threshold necessary to support multi-follicular growth for an entire week. The optimal dose of long-acting FSH is still being determined. A single injection of long-acting FSH can replace seven daily FSH injections during the first week of controlled ovarian stimulation (COS) and can make assisted reproduction more patient friendly.

OBJECTIVES

To compare the effectiveness of long-acting FSH versus daily FSH in terms of pregnancy and safety outcomes in women undergoing IVF or ICSI treatment cycles.

SEARCH METHODS

We searched the following electronic databases, trial registers and websites from inception to June 2015: the Cochrane Central Register of Controlled Trials (CENTRAL), the Cochrane Menstrual Disorders and Subfertility Group (MDSG) Specialized Register, MEDLINE, EMBASE, PsycINFO, CINAHL, electronic trial registers for ongoing and registered trials, citation indexes, conference abstracts in the ISI Web of Knowledge, LILACS, Clinical Study Results (for clinical trial results of marketed pharmaceuticals), PubMed and OpenSIGLE. We also carried out handsearches.

SELECTION CRITERIA

We included all randomised controlled trials (RCTs) comparing long-acting FSH versus daily FSH in women who were part of a couple with subfertility and undertaking IVF or ICSI treatment cycles with a GnRH antagonist or agonist protocol.

DATA COLLECTION AND ANALYSIS

Two review authors independently performed study selection, data extraction and assessment of risk of bias. We contacted trial authors in cases of missing data. We calculated risk ratios for each outcome, and our primary outcomes were live birth rate and ovarian hyperstimulation syndrome (OHSS) rate. Our secondary outcomes were ongoing pregnancy rate, clinical pregnancy rate, multiple pregnancy rate, miscarriage rate, any other adverse event (including ectopic pregnancy, congenital malformations, drug side effects and infection) and patient satisfaction with the treatment. Trials reported all outcomes, except patient satisfaction with the treatment.

MAIN RESULTS

We included six RCTs with a total of 3753 participants and we graded the quality of the included studies as moderate. All studies included women with an indication for COS as part of an IVF/ICSI cycle with age ranging from 18 to 41 years. A comparison of long-acting FSH versus daily FSH did not show evidence of difference in effect on overall live birth rate (Risk ratio (RR) 0.95, 95% confidence interval (CI) 0.84 to 1.07; 2363 participants, eight studies; I² statistic = 44%) or OHSS (RR 1.00, 95% CI 0.74 to 1.37; 3753 participants, nine studies; I² statistic = 0%). We compared subgroups by dose of long-acting FSH. There was evidence of reduced live birth rate in women who received lower doses (60 to 120 μg) of long-acting FSH compared to daily FSH (RR 0.70, 95% CI 0.52 to 0.93; 645 participants, three studies; I² statistic = 0%). There was no evidence a difference between the groups in live births in the medium dose (150 to 180 μg) subgroup (RR 1.03, 95% CI 0.90 to 1.18; 1685 participants, four studies; I² statistic = 6%). There was no evidence of a difference between the groups in the clinical pregnancy rate (any dose), ongoing pregnancy rate (any dose), multiple pregnancy rate (any dose), miscarriage rate (low or medium dose), ectopic pregnancy rate (any dose), congenital malformation rate, congenital malformation rate; major or minor (low or medium dose).

AUTHORS' CONCLUSIONS

The use of a medium dose (150 to 180 μg) of long-acting FSH is a safe treatment option and equally effective compared to daily FSH in women with unexplained subfertility. There was evidence of reduced live birth rate in women receiving a low dose (60 to 120 μg) of long-acting FSH compared to daily FSH. Further research is needed to determine whether long-acting FSH is safe and effective for use in hyper- or poor responders and in women with all causes of subfertility.

Gonadotrophins: The future

The role of the IVF clinician is to make the ART treatment safe, patient-friendly, cost effective and at the same time offer good and high quality treatment. IVF protocols are a burden for women and are one of the potential reasons why women don’t return for subsequent cycles. Frequent injections may increase stress and also result in high error rates. Simple short treatment regimen with optimal recovery of good quality oocytes results in development of good quality embryos followed by SET in treatment and cryopreservation cycles are a less burden and result in related lesser discontinuation, side effects, treatment cycles in time and are more cost-effective.

Development of FSH analogues with longer terminal t1/2 and slower absorption to peak serum levels will increase the efficiency, decrease the side effects and also is easy to administer. This makes it convenient for the patients increasing the compliance. A certain minimum LH concentration is necessary for adequate thecal cell function and subsequent oestradiol synthesis in the granulosa cells. Adjuvant r-HLH gives clinician's precise control over the dose of LH bioactivity administered to target the therapeutic window. New parenteral, transdermal, inhaled and oral fertility drugs and regimens are currently under research and development with the objective to further simplify treatment for ART.

Structure-function relationships of glycoprotein hormones and their subunits' ancestors

Glycoprotein hormones (GPHs) are the most complex molecules with hormonal activity. They exist only in vertebrates but the genes encoding their subunits' ancestors are found in most vertebrate and invertebrate species although their roles are still unknown. In the present report, we review the available structural and functional data concerning GPHs and their subunits' ancestors.

Effect of time and dose of recombinant follicle stimulating hormone agonist on the superovulatory response of sheep

The objective of this study was to determine the superovulatory potential of a single-chain analog of human FSH (Fcα) when administered to ewes either 3 days before, or coincident with, simulated luteolysis (pessary removal [PR]). A total of 40 animals were randomly assigned to receive Fcα at doses of 0.62, 1.25, or 2.5 IU/kg of body weight (bwt) 3 days before PR or 0.31, 0.62, 1.25, or 2.5 IU/kg of bwt at PR. Control ewes received protein without FSH activity. Blood samples were collected during the periovulatory period and ovarian tissue was collected 11 days after PR. Ovulation rate did not differ from the control group in ewes receiving the smallest doses of Fcα (0.31 and 0.62 IU/kg). However, a significant superovulatory response was noted in sheep receiving Fcα at doses of 1.25 and 2.5 IU/kg and this response was comparable in animals receiving the largest dose levels of Fcα at, or 3 days before, PR. The interval between PR and the LH surge was significantly extended and the LH surges were less synchronous in animals receiving Fcα at PR when compared with animals receiving the potent FSH agonist 3 days before PR. Taken together, these data indicate that the human single-chain gonadotropin with FSH activity promotes superovulation in ewe lambs in the breeding season. A single injection of the recombinant gonadotropin 3 days before luteolysis synchronizes the LH surge. The use of the single-chain analog of FSH in assisted reproduction for domestic animals is likely to be of practical significance as an alternative to conventional gonadotropins in superovulation protocols in livestock species.

Gonadotropin therapy in assisted reproduction: an evolutionary perspective from biologics to biotech

Gonadotropin therapy plays an integral role in ovarian stimulation for infertility treatments. Efforts have been made over the last century to improve gonadotropin preparations. Undoubtedly, current gonadotropins have better quality and safety profiles as well as clinical efficacy than earlier ones. A major achievement has been introducing recombinant technology in the manufacturing processes for follicle-stimulating hormone, luteinizing hormone, and human chorionic gonadotropin. Recombinant gonadotropins are purer than urine-derived gonadotropins, and incorporating vial filling by mass virtually eliminated batch-to-batch variations and enabled accurate dosing. Recombinant and fill-by-mass technologies have been the driving forces for launching of prefilled pen devices for more patient-friendly ovarian stimulation. The most recent developments include the fixed combination of follitropin alfa + lutropin alfa, long-acting FSH gonadotropin, and a new family of prefilled pen injector devices for administration of recombinant gonadotropins. The next step would be the production of orally bioactive molecules with selective follicle-stimulating hormone and luteinizing hormone activity.

Long-acting FSH versus daily FSH for women undergoing assisted reproduction

BACKGROUND

Assisted reproduction techniques (ART) such as in vitro fertilisation (IVF) and intracytoplasmic sperm injection (ICSI) can help subfertile couples to create a family. It is necessary to induce multiple follicles; this is achieved by follicle stimulating hormone (FSH) injections. Current treatment regimens prescribe daily injections of FSH (urinary FSH with or without luteinizing hormone (LH) injections or recombinant FSH (rFSH)).Recombinant DNA technologies have produced a new recombinant molecule which is a long-acting FSH, named corifollitropin alfa (Elonva) or FSH-CTP. A single dose of long-acting FSH is able to keep the circulating FSH level above the threshold necessary to support multi-follicular growth for an entire week. The optimal dose of long-acting FSH is still being determined. A single injection of long-acting FSH can replace seven daily FSH injections during the first week of controlled ovarian stimulation (COS) and can make assisted reproduction more patient friendly.

OBJECTIVES

To compare the effectiveness of long-acting FSH versus daily FSH in terms of pregnancy and safety outcomes in women undergoing IVF or ICSI treatment cycles.

SEARCH METHODS

We searched the following electronic databases, trial registers and websites: the Cochrane Central Register of Controlled Trials (CENTRAL), the Menstrual Disorders and Subfertility Group (MDSG) Specialised Register, MEDLINE, EMBASE, PsycINFO, CINAHL, electronic trial registers for ongoing and registered trials, citation indexes, conference abstracts in the ISI Web of Knowledge, LILACS, Clinical Study Results (for clinical trial results of marketed pharmaceuticals), PubMed and OpenSIGLE (10 October 2011). We also carried out handsearches.

SELECTION CRITERIA

All randomised controlled trials (RCTs) comparing long-acting FSH versus daily FSH in women who were part of a couple with subfertility and undertaking IVF or ICSI treatment cycles with a GnRH antagonist or agonist protocol were included.

DATA COLLECTION AND ANALYSIS

Data extraction and assessment of risk of bias was independently done by two review authors. Original trial authors were contacted in the case of missing data. We calculated Peto odds ratios for each outcome; our primary outcomes were live birth rate and ovarian hyperstimulation syndrome (OHSS) rate.

MAIN RESULTS

We included four RCTs with a total of 2335 participants. A comparison of long-acting FSH versus daily FSH did not show evidence of difference in effect on overall live birth rate (Peto OR 0.92; 95% CI 0.76 to 1.10, 4 RCTs, 2335 women) or OHSS (Peto OR 1.12; 95% CI 0.79 to 1.60, 4 RCTs, 2335 women). We compared subgroups by dose of long-acting FSH. There was evidence of reduced live birth rate in women who received lower doses (60 to 120 μg) of long-acting FSH compared to daily FSH (Peto OR 0.60; 95% CI 0.40 to 0.91, 3 RCTs, 645 women). There was no evidence of effect on live births in the medium dose subgroup (Peto OR 1.03; 95% CI 0.84 to 1.27) and no evidence of effect on clinical pregnancy rate, ongoing pregnancy rate, multiple pregnancy rate, miscarriage rate or ectopic pregnancy rate.

AUTHORS' CONCLUSIONS

The use of a medium dose of long-acting FSH is a safe treatment option and equally effective compared to daily FSH. Further research is needed to determine if long-acting FSH is safe and effective for use in hyper- or poor responders and in women with all causes of subfertility.

Prospective follow-up of 838 fetuses conceived after ovarian stimulation with corifollitropin alfa: comparative and overall neonatal outcome

STUDY QUESTION

Is treatment with corifollitropin alfa, a new recombinant gonadotrophin with sustained follicle-stimulating activity, safe in terms of perinatal complications and birth defects in infants conceived following corifollitropin alfa treatment for contolled ovarian stimulation (COS)?

SUMMARY ANSWER

In terms of neonatal outcome and risk of malformations, treatment with a single dose of corifollitropin alfa during COS is as safe as treatment with daily recombinant FSH (rFSH).

WHAT IS KNOWN AND WHAT THIS PAPER ADDS

This is the first pooled analysis of individual safety data in terms of neonatal outcome and major and minor congenital malformations collected following intervention trials of corifollitropin alfa.

DESIGN

Pregnancy and follow-up studies were conducted prospectively and data were collected from all Phase II and III trials with corifollitropin alfa intervention, including two comparative randomized controlled trials (RCTs) in which patients received either a single dose of corifollitropin alfa or daily rFSH for the first 7 days of COS. Patients with ongoing pregnancies at 10 weeks after embryo transfer were followed up to labour and the health of the offspring was assessed up to 4-12 weeks after birth.

PARTICIPANTS AND SETTING

Following corifollitropin alfa treatment prior to IVF or ICSI, the health of 677 pregnant women, 838 fetuses and 806 live born infants was evaluated.

MAIN RESULTS AND THE ROLE OF CHANCE

Among 440 fetuses in the corifollitropin alfa arm and 381 fetuses in the rFSH arm of the two RCTs, there were 424 (96.4%) and 370 (98.7%) live births, respectively. Neonatal characteristics, the frequency of premature births and the incidence of infant adverse events were similar in both treatment arms. The overall incidence of any congenital malformations in live born infants was 16.3 and 17.0%, with major malformation rates of 4.0 and 5.4% in the corifollitropin alfa and rFSH groups, respectively [odds ratio (OR) for major malformations, 0.71; 95% confidence interval, 0.36-1.38]. From 838 fetuses assessed in all corifollitropin alfa intervention trials, there were 806 (96.2%) live births with a major malformation rate of 4.5% in live born infants.

BIAS, CONFOUNDING AND OTHER REASONS FOR CAUTION

Both RCTs had a double-blind and active-controlled design and the adjudication of congenital malformations was also performed in a blinded fashion. As the total number of major malformations was limited (37), the confidence interval around the OR was rather wide. GENERALISABILITY TO OTHER POPULATIONS: The similarity of corifollitropin alfa and rFSH with respect to the incidence of congenital malformations was consistent across the RCTs and pregnancy type (singleton, multiple). This suggests that this similarity could hold in general. Overall incidences, however, may depend on the definitions of malformations and rules to adjudicate these events as major or minor.

Is there a place for corifollitropin alfa in IVF/ICSI cycles? A systematic review and meta-analysis

OBJECTIVE

To evaluate the role of corifollitropin alfa, a newly developed weekly administrated long-acting recombinant FSH (rFSH), as an alternative for daily rFSH administration in women undergoing controlled ovarian stimulation in GnRH antagonist down-regulated in vitro fertilization (IVF)/intracytoplasmic sperm injection (ICSI) treatment cycles.

DESIGN

Systematic review and meta-analysis of randomized controlled trials.

SETTING

University and private centers.

PATIENT(S)

Infertile women undergoing IVF/ICSI treatment.

INTERVENTION(S)

Comparing long-acting rFSH corifollitropin alfa versus standard daily administrated rFSH in GnRH antagonist IVF/ICSI cycles.

MAIN OUTCOME MEASURE(S)

Ongoing pregnancy rate, live birth rate, clinical pregnancy rate, miscarriage rate, duration of stimulation, amount of FSH, number of retrieved oocytes, number of mature oocytes, number of embryos obtained, fertilization rate, ovarian hyperstimulation syndrome (OHSS) incidence, and adverse events. Searches (of literature through November 2011) were conducted in Medline, Embase, Science Direct, the Cochrane Library, and databases of abstracts.

RESULT(S)

Four randomized trials involving 2,326 women were included. There was no evidence of a statistically significant difference in ongoing pregnancy rate for corifollitropin alfa versus rFSH. There was evidence of increased ovarian response and risk of OHSS in corifollitropin alfa.

CONCLUSION(S)

In view of its equivalence and safety profile, corifollitropin alfa in combination with daily GnRH antagonist seems to be an alternative for daily rFSH injections in normal responder patients undergoing ovarian stimulation in IVF/ICSI treatment cycles.

Corifollitropin alfa: a review of its use in controlled ovarian stimulation for assisted reproduction

Corifollitropin alfa (Elonva®) is a fusion product of human follicle-stimulating hormone (FSH) and the C-terminal peptide of the β-subunit of human chorionic gonadotropin (hCG) produced by recombinant DNA technology. It has the same pharmacologic activity as FSH and recombinant FSH (rFSH; follitropin alfa; follitropin beta), but with a slower absorption and a longer half-life. Corifollitropin alfa is indicated as a multifollicular stimulant for women undergoing controlled ovarian stimulation using gonadotropin-releasing hormone (GnRH) antagonist-assisted reproduction protocols. In two large, randomized, double-blind, phase III trials, a single subcutaneous injection of corifollitropin alfa was no less effective as a multifollicular stimulant than seven once-daily injections of rFSH when used as part of a GnRH antagonist-assisted controlled ovarian stimulation cycle. With regard to primary endpoints, the mean number of retrieved oocytes per started cycle demonstrated that the two treatments were equivalent, and the ongoing pregnancy rate in recipients of corifollitropin alfa was noninferior to that in recipients of rFSH. The median duration of stimulation with FSH was 9 days in both treatment arms of both trials, which means that, on average, recipients of corifollitropin alfa required only 2 further days of stimulation with rFSH prior to triggering oocyte maturation with the administration of hCG. Fertilization rates were high, ranging from 66% to 68%, in recipients of corifollitropin alfa or rFSH in both trials. When used as part of a GnRH antagonist-assisted reproduction protocol, corifollitropin alfa was generally well tolerated, with a tolerability profile similar to that of rFSH. In large, pooled analyses of clinical trials, the incidence of ovarian hyperstimulation syndrome in both the corifollitropin alfa and rFSH treatment arms was consistent with that expected in the relatively young patient population. Furthermore, there were no clinically relevant differences in pregnancy complications and the incidence of infant adverse events between treatment arms. In conclusion, a single subcutaneous injection of corifollitropin alfa provides sustained multifollicular stimulation for up to a week in women undergoing controlled ovarian stimulation. Compared with seven once-daily injections of rFSH, a single injection of corifollitropin alfa achieves equivalent efficacy, and provides a well tolerated and more convenient treatment option to induce multiple follicular growth prior to assisted reproduction.

The role of corifollitropin alfa in controlled ovarian stimulation for IVF in combination with GnRH antagonist

Corifollitropin alfa is a synthetic recombinant follicle-stimulating hormone (rFSH) molecule containing a hybrid beta subunit, which provides a plasma half-life of ∼65 hours while maintaining its pharmocodynamic activity. A single injection of corifollitropin alfa can replace daily FSH injections for the first week of ovarian stimulation for in vitro fertilization. Stimulation can be continued with daily FSH injections if the need arises. To date, more than 2500 anticipated normoresponder women have participated in clinical trials with corifollitropin alfa. It is noteworthy that one-third of women did not require additional gonadotropin injections and reached human chorionic gonadotropin criterion on day 8. The optimal corifollitropin dose has been calculated to be 100 μg for women with a body weight ≤60 kg and 150 μg for women with a body weight >60 kg, respectively. Combination of corifollitropin with daily gonadotropin-releasing hormone antagonist injections starting on stimulation day 5 seems to yield similar or significantly higher numbers of oocytes and good quality embryos, as well as similar ongoing pregnancy rates compared with women stimulated with daily rFSH injections. Stimulation characteristics, embryology, and clinical outcomes seem consistent with repeated corifollitropin-stimulated assisted reproductive technologies cycles. Multiple pregnancy or ovarian hyperstimulation syndrome rates with corifollitropin were not increased over daily FSH regimen. The corifollitropin alfa molecule does not seem to be immunogenic and does not induce neutralizing antibody formation. Drug hypersensitivity and injection-site reactions are not increased. Incidence and nature of adverse events and serious adverse events are similar to daily FSH injections. Current trials do not provide information regarding use of corifollitropin alfa in anticipated hyper- and poor responders to gonadotropin stimulation. Although corifollitropin alfa is unlikely to be teratogenic, at the moment data on congenital malformations is missing.

Corifollitropin Alfa: A Novel Long-Acting Recombinant Follicle-Stimulating Hormone Agonist for Controlled Ovarian Stimulation

The advent of recombinant technology has made the production of modified proteins with desired properties possible. Corifollitropin alfa is a successful example of the first available long-acting, follicle stimulating hormone. Corifollitropin alfa has prolonged half-life and a slower absorption rate, but has the same receptor-binding and biological activity as recombinant FSH (rFSH). Its application is associated with the arrival of a novel simplified approach for controlled ovarian stimulation in IVF patients. Different studies have proven the efficiency of a single corifollitropin alfa dose to initiate and sustain multiple follicular development in a gonadotropin-releasing hormone antagonist protocol. Finally, corifollitropin alfa is well tolerated and is not correlated with serious adverse events, except for the slightly higher incidence of ovarian hyperstimulation syndrome compared with traditional management with recombinant FSH.

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.

Efficacy of native and hyperglycosylated follicle-stimulating hormone analogs for promoting fertility in female mice

OBJECTIVE

To compare the efficacy of recombinant human FSH (rhFSH) with rhFSH with four additional O-linked carbohydrates (rhFSH-CTP), rhFSH with four additional N-linked carbohydrates (rhFSH-N4), and the current gold standard for rodent ovarian stimulation, pregnant mare serum gonadotropin (PMSG), on fertility parameters in mice.

DESIGN

Animal study.

SETTING

Academic research center.

ANIMAL(S)

Adult C57Bl/6J female mice.

INTERVENTION(S)

Ovarian stimulation with 5 IU of rhFSH, rhFSH-CTP, rhFSH-N4, or PMSG. Forty-six hours later, 5 IU of hCG was injected to promote ovulation and females were mated overnight.

MAIN OUTCOME MEASURE(S)

Eggs retrieved after ovulation, in vitro embryo development, delivery rate, and litter size.

RESULT(S)

The hyperglycosylated FSH analogs, rhFSH-CTP and rhFSH-N4, enhanced ovulation and embryo maturation significantly better than rhFSH. RhFSH-N4 produced more eggs (28.5 +/- 1.9 per mouse) and embryos (17.8 +/- 1.6) compared with rhFSH-CTP (18.3 +/- 1.2 and 9.0 +/- 1.0, respectively). Treatment with rhFSH, rhFSH-N4, and PMSG produced statistically equivalent delivery rates and litter sizes. The delivery rate was surprisingly lower with rhFSH-CTP (14%) compared with PMSG (33%).

CONCLUSION(S)

Compared with rhFSH, treatment with hyperglycosylated rhFSH-CTP and rhFSH-N4 led to superior rates of ovulated eggs and subsequent in vitro embryo development. RhFSH-N4 was equivalent to PMSG, while all of the fertility parameters studied were lower with rhFSH-CTP than with PMSG therapy.

Is there a need for recombinant human luteinizing hormone (lutropin alfa) supplementation in ovarian stimulation for assisted reproduction?

Luteinizing hormone is now available as the recombinant product, lutropin alfa for the treatment of female infertility. It is necessary in the natural process of follicular growth and maturation. It is not yet clear which patients really benefit from the addition of this medication to conventional gonadotropin stimulation procedures in infertility treatment. Certainly, it has a proven benefit in patients suffering from hypogonadotropic hypogonadism (WHO I). Others may be older patients, patients with a profound gonadotropin suppression stimulated in long gonadotropin-releasing hormone agonist protocols, or patients with poor ovarian response to conventional stimulation strategies. The available data are reviewed herein.

The science behind 25 years of ovarian stimulation for in vitro fertilization

To allow selection of embryos for transfer after in vitro fertilization, ovarian stimulation is usually carried out with exogenous gonadotropins. To compensate for changes induced by stimulation, GnRH analog cotreatment, oral contraceptive pretreatment, late follicular phase human chorionic gonadotropin, and luteal phase progesterone supplementation are usually added. These approaches render ovarian stimulation complex and costly. The stimulation of multiple follicular development disrupts the physiology of follicular development, with consequences for the oocyte, embryo, and endometrium. In recent years, recombinant gonadotropin preparations have become available, and novel stimulation protocols with less detrimental effects have been developed. In this article, the scientific background to current approaches to ovarian stimulation for in vitro fertilization is reviewed. After a brief discussion of the relevant aspect of ovarian physiology, the development, application, and consequences of ovarian stimulation strategies are reviewed in detail.

FSH and folliculogenesis: from physiology to ovarian stimulation

FSH is a glycoprotein hormone consisting of two peptide subunits. The role of FSH in folliculogenesis is well known: to stimulate the formation of a large pre-ovulatory follicle that, because of its FSH-dependent maturation, is capable of ovulation and forming a corpus luteum in response to the mid-cycle surge of LH. FSH is widely used in ovarian stimulation for assisted reproduction techniques. Ovarian stimulation protocols combine the use of human menopausal gonadotrophin, urinary FSH or recombinant FSH with gonadotrophin-releasing hormone (GnRH) agonists or antagonists in order to increase oocyte number and to avoid premature LH surge. Recently, the availability of recombinant LH has permitted new stimulation protocols, combining recombinant FSH, recombinant LH and GnRH antagonists. Due to the limitations of the new Italian law in terms of the number of oocytes that can be fertilized, protocols with a softer ovarian stimulation are now considered, reducing risk of ovarian hyperstimulation syndrome, multiple pregnancies and emotional and physical burdens on the patients. Long-acting FSH preparations are also under clinical study. Knowledge of the stereochemical three-dimensional structure of FSH and its receptor will allow the study of new non-peptide orally administered molecules that fit the FSH receptors.

Clinical pharmacology of gonadotrophin preparations

The practice of ovulation induction and superovulation for IVF has progressed in many ways since the first reports of pregnancies after IVF over 25 years ago. The pharmacology of gonadotrophins has advanced alongside other developments, leading to safer, easier and more effective treatments for anovular infertility and IVF ovulation induction. This review uses current concepts of the basic physiology of gonadotrophin actions during the natural ovarian cycle as a starting point from which to assess their uses in anovulation and assisted reproduction. The relative merits of urinary and recombinant gonadotrophins are discussed, along with their uses in combination with gonadotrophin-releasing hormone agonists and antagonists.

Molecular pharmacology of gonadotropins

Gonadotropins have been studied in biological systems for decades and many of their properties are well defined. These include pharmacological properties such as affinity, stability, and pharmacokinetics also used to characterize drugs. Technologies applied to research on gonadotropins have led to the creation of hormone analogs with alterations to one or more of these proper-ties. Some of these analogs have potential therapeutic applications. A challenge to realizing this potential is the accurate prediction of how these compounds will perform in humans. This could be facilitated by advances in biological models and the understanding of specific effects of the hormones on their receptors.