New developments in gonadotrophin pharmacology

Review of the safety, efficacy, costs and patient acceptability of recombinant follicle-stimulating hormone for injection in assisting ovulation induction in infertile women

Anovulation is a common cause of female subfertility. Treatment of anovulation is aimed at induction of ovulation. In women with clomiphene-citrate resistant WHO group II anovulation, one of the treatment options is ovulation induction with exogenous follicle-stimulating hormone (FSH or follitropin). FSH is derived from urine or is produced as recombinant FSH. Two forms of recombinant FSH are available - follitropin alpha and follitropin beta. To evaluate the efficacy, safety, costs and acceptability of recombinant FSH, we performed a review to compare recombinant FSH with urinary-derived FSH products. Follitropin alpha, beta and urinary FSH products appeared to be equally effective in terms of pregnancy rates. Patient safety was also found to be comparable, as the incidence of side effects including multiple pregnancies was similar for all FSH products. In practice follitropin alpha and beta may be more convenient to use due to the ease of self-administration, but they are also more expensive than the urinary products.

A prospective, randomised, controlled clinical study on the assessment of tolerability and of clinical efficacy of Merional (hMG-IBSA) administered subcutaneously versus Merional administered intramuscularly in women undergoing multifollicular ovarian stimulation in an ART programme (IVF)

BACKGROUND

Multifollicular ovarian stimulation (MOS) is widely used in IVF and the compliance to treatment is deeply influenced by the tolerability of the medication(s) used and by the ease of self-administration. This prospective, controlled, randomised, parallel group open label, multicenter, phase III, equivalence study has been aimed to compare the clinical effectiveness (in terms of oocytes obtained) and tolerability of subcutaneous (s.c.) self-administered versus classical intramuscular (i.m.) injections of Merional, a new highly-purified hMG preparation.

METHODS

A total of 168 normogonadotropic women undergoing IVF were enrolled. Among them, 160 achieved pituitary suppression with a GnRH-agonist long protocol and were randomised to MOS treatment with Merional s.c. or i.m. They started MOS with a standard hMG dose between 150-300 IU, depending upon patient's age, and underwent a standard IVF procedure.

RESULTS

No statistically significant difference in the mean number of collected oocytes (primary endpoint) was observed between the two study subgroups (7.46, SD 4.24 vs. 7.86, SD 4.28 in the s.c. and i.m. subgroups, respectively). As concerns the secondary outcomes, both the pregnancy and the clinical pregnancy rates were comparable between subgroups. The incidence of adverse events was similar in the two groups (2.4% vs. 3.7%, respectively). Pain at injection site was reported only the i.m. group (13.9% of patients).

CONCLUSION

Merional may be used by s.c. injections in IVF with an effectiveness in terms of retrieved oocytes that is equivalent to the one obtained with i.m administration and with a better local tolerability. With the limitations due to the sample size af this study, s.c. and i.m. administration routes seem to have the same overall safety.

The importance of consistent FSH delivery in infertility treatment

The use of gonadotrophins for the treatment of infertility began in the 1930s following early work on the pituitary-ovarian axis and the discovery of FSH and LH. The technological development of pharmaceutical gonadotrophins over the last 60 years has shown improvements in specific activity, purity, degradation and detection of impurities. Throughout these pharmaceutical developments the gonadotrophin content of both urinary and recombinant preparations has been assessed using an animal in-vivo bioassay. This paper reviews the manufacturing history of recombinant human FSH (r-FSH) and follitropin-alfa filled-by-mass (FbM), and evaluates the impact of introducing a pharmaceutical product that is formulated and assayed by a physicochemical method for r-FSH protein content. This consistent gonadotrophin preparation offers the opportunity to reconsider protocols of induction in a new light, deciding the daily amount of r-FSH in relation to specific clinical parameters such as the mean ovarian volume (MOV), basal FSH concentration and body mass index (BMI). Preliminary data on the application of the formula 'basal FSH x BMI/MOV x (5.5/75)' gave interesting results as a new method to standardize the induction therapy. A formula is proposed for deciding the first 5 days of drug administration.

FSH isoform composition of commercial gonadotrophin preparations: a neglected aspect?

The clinical efficacy of commercial gonadotrophin preparations has been the subject of an intense debate during recent years. Arguments have primarily focused on the origin of FSH activity (urine versus recombinant derived) and whether the preparation included LH-like activity. FSH isoform composition has received little or no attention, and is usually considered to have negligible effect on clinical effectiveness. By presenting the available data on the FSH isoform composition of commercial gonadotrophin preparations, the present paper challenges this assumption. To evaluate whether the FSH isoform composition affected the efficacy of a product, a meta-analysis was performed that compared a preparation expressing an acidic isoform profile (urinary-derived Metrodin-HP) with a preparation rich in less acidic isoforms (recombinant derived Gonal F). A total of five randomized clinical trials that specifically compared these two preparations was identified and included in the analysis. All parameters relating to the direct effect of FSH on the follicle differed significantly in favour of the product rich in less acidic isoforms, while data on pregnancy outcome did not reach significance. The importance of the FSH isoform profile and whether the FSH is derived from urine or by recombinant technique is discussed in relation to clinical efficacy. It is suggested that the FSH isoform profile of commercial gonadotrophin preparations is of clinical importance and should be taken into account when evaluating efficacy.

Continued improvements in the quality and consistency of follitropin alfa, recombinant human FSH

The use of gonadotrophins for the treatment of infertility began in the 1930s following early work on the pituitary-ovarian axis and the discovery of FSH and LH. The technological development of pharmaceutical gonadotrophins over the last 40 years has shown improvements in specific activity, purity, degradation and impurities. Throughout these pharmaceutical developments the gonadotrophin content of both urinary and recombinant preparations has been assessed using an animal in-vivo bioassay. This paper reflects upon the manufacturing history of recombinant human FSH (r-hFSH) and follitropin alfa filled by mass (FbM), and evaluates the impact of introducing a pharmaceutical product that is formulated and assayed by a physicochemical method for r-hFSH protein content. It also compares the analytical consistency of follitropin alfa FbM with another commercially available r-hFSH, follitropin beta.

Compositional analyses of a human menopausal gonadotrophin preparation extracted from urine (menotropin). Identification of some of its major impurities

Recently, a highly purified human menopausal gonadotrophin preparation (HMG) was launched. The composition and purity of this HMG (Menopur); Ferring Pharmaceuticals) with a claimed 1:1 ratio of FSH and LH was determined. Three gonadotrophins were observed: FSH, LH and human chorionic gonadotrophin (HCG). The immunoactivity for HCG was three-fold higher than the immunoactivity for LH. Because of the longer half-life of HCG as compared with LH, about 95% of the in-vivo LH-receptor-mediated bioactivity is attributable to the presence of HCG. This is substantiated by biochemical analyses. To the best of the authors' knowledge, this relatively high amount of HCG can only be explained by assuming the addition of HCG from external sources, which is a well established practice for standardization purposes. In addition to gonadotrophins, a number of other proteins were detected. The amount of these impurities, as determined by reversed-phase high-performance liquid chromatography on a peak-area basis, is at least 30%. Therefore, it is concluded that this HMG preparation contains at most 70% gonadotrophins. Via a proteomics approach three major impurities were identified: leukocyte elastase inhibitor, protein C inhibitor, and zinc-alpha(2)-glycoprotein. On the basis of the results obtained in this study, a comparison is made with recombinant FSH.

Time to revolutionize the triggering of ovulation

Methods used for ovarian stimulation constantly change with advances in gonadotrophin therapy. In this Commentary, an appeal is made for more attention to the use of LH for the induction of ovulation. Its typical characteristics during the LH surge are finely balanced to induce normal ovulation and luteinization. It does not induce ovarian hyperstimulation, for example. The recent commercial availability of recombinant LH (LHr) offers a chance of escaping from the use of urinary human chorionic gonadotrophin (HCG) and its varied forms such as those with a shorter half-life. It should also avoid the weakly effective bursts of FSH and LH and weak luteal phases released associated with the use of gonadotrophin-releasing hormone agonists. Currently, large dosages of LHr are needed to match the endocrine events typical of inducing ovulation by the endogenous LH surge. In the interests of patients' safety and improved forms of luteal phase endocrinology, research should be devoted to improving the properties of rLH to make it induce surges similar to endogenous discharges. This would replace the current use of HCG to induce ovulation, with its attendant risks of ovarian hyperstimulation and luteal phase anomalies.

Ovarian responses to recombinant FSH or HMG in normogonadotrophic women following pituitary desensitization by a depot GnRH agonist for assisted reproduction

At present, there is considerable debate about the utility of supplemental LH in assisted reproduction treatment. In order to explore this, the present authors used a depot gonadotrophin-releasing hormone agonist (GnRHa) protocol combined with recombinant human FSH (rhFSH) or human menopausal gonadotrophin (HMG) in patients undergoing intracytoplasmic sperm injection (ICSI). The response to either rhFSH (75 IU FSH/ampoule; group rhFSH, 25 patients) or HMG (75 IU FSH and 75 IU LH/ampoule; group HMG, 25 patients) was compared in normo-ovulatory women suppressed with a depot triptorelin injection and candidates for ICSI. A fixed regimen of 150 IU rhFSH or HMG was administered in the first 14 days of treatment. Treatment was monitored with transvaginal pelvic ultrasonographic scans and serum measurement of FSH, LH, oestradiol, androstenedione, testosterone, progesterone, inhibin A, inhibin B and human chorionic gonadotrophin (HCG) at 2-day intervals. Although oestradiol serum concentrations on the day of HCG injection were similar, both the duration of treatment and the per cycle gonadotrophin dose were lower in group HMG. In the initial 16 days of gonadotrophin treatment, the area under the curve (AUC) of LH, oestradiol, androstenedione and inhibin B were higher in group HMG; no differences were seen for the remaining hormones measured, including the inhibin B:inhibin A ratio. The dynamics of ovarian follicle development during gonadotrophin treatment were similar in both study groups, but there were more leading follicles (>17 mm in diameter) on the day of HCG injection in the rhFSH group. The number of oocytes, mature oocytes and good quality zygotes and embryos obtained were significantly increased in the rhFSH group. It is concluded that in IVF patients undergoing pituitary desensitization with a depot agonist preparation, supplemental LH may be required in terms of treatment duration and gonadotrophin consumption. However, both oocyte, embryo yield and quality were significantly higher with the use of rhFSH.