Transepithelial transport across the blood-testis barrier.

The blood-testis barrier protects developing germ cells by limiting the entry of xenobiotics into the adluminal compartment. There is strong evidence that the male genital tract can serve as a sanctuary site, an area of the body where tumors or viruses are able to survive treatments because most drugs are unable to reach therapeutic concentrations. Recent work has classified the expression and localization of endogenous transporters in the male genital tract as well as the discovery of a transepithelial transport pathway as the molecular mechanism by which nucleoside analogs may be able to circumvent the blood-testis barrier. Designing drug therapies that utilize transepithelial transport pathways may improve drug disposition to this sanctuary site. Strategies that improve disposition into the male genital tract could reduce the rate of testicular relapse, decrease viral load in semen, and improve therapeutic strategies for male fertility.

LAPS-FSH: a new and effective long-acting follicle-stimulating hormone analogue for the treatment of infertility.

Although several long-acting follicle-stimulating hormone (FSH) therapies have been developed to enhance the ovarian response, a disadvantage of FSH therapy is its relatively short half-life, which requires women to receive one to two injections per day for almost 2 weeks. In the present study, we developed a novel FSH analogue by conjugating recombinant human FSH (rhFSH) and the constant region of the human immunoglobulin G4 fragment via non-peptidyl linkers. The efficacy of the FSH analogue was evaluated in vitro by cAMP level assessments, pharmacokinetic studies and a determination of ovarian weight and by comparing these findings with the results from other FSH analogues. In addition, the total number of antral and Graafian follicles was determined after 7 days of treatment with control, 6µgkg(-1) follitropin ß, 6, 12 or 42µgkg(-1) corifollitropin α or 3, 6 or 12µgkg(-1) long acting protein/peptide discovery-follicle-stimulating hormone (LAPS-FSH). As a result, the animals treated with 12µgkg(-1) LAPS-FSH produced additional and larger healthy follicles. These data demonstrate that LAPS-FSH promotes growth and inhibits atresia of the ovarian follicle compared with other available drugs, suggesting that our new drug enhances the efficacy and duration of treatment. It is expected that our new FSH analogue will result in a higher chance of pregnancy in patients who are unresponsive to other drugs.

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.

Corifollitropin alfa, a long-acting follicle-stimulating hormone agonist for the treatment of infertility.

Corifollitropin alfa is being developed by Schering-Plough Corp as an injectable, long-acting follicle-stimulating hormone (FSH) agonist for the treatment of infertility. A single dose of corifollitropin alfa could initiate and sustain multifollicular growth in patients undergoing controlled ovarian stimulation, such as during in vitro fertilization or intracytoplasmic sperm injection. The agent comprises an alpha-subunit, which is identical to that of FSH, and a beta-subunit, which is produced by the fusion of the C-terminal peptide from the beta-subunit of chorionic gonadotropin to the beta-subunit of FSH. Corifollitropin alfa has a longer half-life compared with FSH and thus requires less frequent dosing. The drug was well tolerated and does not appear to be associated with any serious adverse events or the formation of antibodies. The initial results from a large, phase III, double-blind clinical trial indicated that the ongoing pregnancy rate achieved with corifollitropin alfa treatment was high and similar to the rate established with daily treatment of recombinant FSH. The number of oocytes retrieved following the administration of corifollitropin alfa was slightly higher compared with the number observed with daily recombinant FSH treatment. Thus, corifollitropin alfa has the potential to serve as a viable fertility agent and to gain a place in the infertility market.