Clinical approach to the evaluation of sperm-cervical mucus interactions

ZB-06, a vaginal film containing an engineered human contraceptive antibody (HC4-N), demonstrates safety and efficacy in a phase 1 postcoital test and safety study

BACKGROUND

With an unplanned pregnancy rate of 50% or more in many countries, there is an urgent need for contraceptives that are more accessible and acceptable. To meet the growing demand for new contraceptives, ZabBio developed ZB-06, a vaginal film containing HC4-N, a human contraceptive antibody that inactivates sperm.

OBJECTIVE

This study aimed to assess the potential contraceptive activity of the ZB-06 film using a surrogate assessment for contraceptive efficacy, the postcoital test. We also assessed clinical safety of film use among healthy heterosexual couples. Serum, cervical mucus, and vaginal fluid HC4-N antibody concentrations and sperm agglutination potency were determined after single film use. Changes in the concentration of soluble proinflammatory cytokines and vaginal Nugent score after film use were measured as subclinical safety endpoints.

STUDY DESIGN

This was a phase 1, first-in-woman, open-label, proof-of-concept, postcoital test and safety study.

RESULTS

A total of 20 healthy women were enrolled in the study, and 8 heterosexual couples completed all study visits. The product was safe for both female participants and their male sexual partners. The postcoital test performed on ovulatory cervical mucus at baseline (no product use) revealed a mean of 25.9 (±30.6) progressively motile sperm per high-power field. After use of a single ZB-06 film before intercourse, this number dropped to 0.04 (±0.06) progressively motile sperm per high-power field (P<.0001). At the follow-up postcoital test visit approximately 1 month later (no product use), a mean of 47.4 (±37.4) progressively motile sperm per high-power field was observed, indicating contraceptive reversibility.

CONCLUSION

A single dose of the ZB-06 film applied before intercourse was safe and met efficacy surrogate benchmarks of excluding progressively motile sperm from ovulatory cervical mucus. These data indicate that ZB-06 is a viable contraceptive candidate warranting further development and testing.

The postcoital test in the development of new vaginal contraceptives†

Postcoital tests (PCTs) have been used for over a century in the clinical evaluation of infertile couples, and for nearly 70 years in the evaluation of new vaginal contraceptive products. PCTs have been largely replaced by more modern methods in the study of infertility, but they remain the most useful way to obtain preliminary data on the effectiveness of vaginal contraceptive products. The World Health Organization has described important aspects of the procedure. It involves collection of cervical mucus at a certain time point after intercourse and the counting and characterization of sperm found in the mucus. A wide range of progressively motile sperm (PMS) has been associated with pregnancy rates in infertility studies. Eligibility for contraceptive trials includes the requirement that couples achieve a certain threshold number of PMS per high power field at midcycle in a baseline cycle without the test product. The primary endpoint, or definition of a satisfactory result in test cycles, is predefined. A literature review identified 10 PCT studies of vaginal contraceptives involving nine test products. Phase II trials of vaginal contraceptives have not been deemed feasible in the development of any vaginal contraceptive to date. A PCT study of a test product can be predictive of contraceptive efficacy, although ultimate contraceptive effectiveness is influenced by the ease of use of the product, along with patient compliance. PCT results similar to results seen with products that later showed satisfactory performance in efficacy trials is the best indicator of likely success of a test product.

Comparative in vitro spermicidal activity of chelating agents and synergistic effect with nonoxynol-9 on human sperm functionality

Nonoxynol-9 (N-9), a nonionic surfactant, exerts both spermicidal and anti-viral activities and is the most widely used spermicide. Although N-9 has been regarded as an efficient spermicidal agent for barrier contraception, it has been reported to cause vaginal irritation and allergic vaginitis, and its spermicidal action in the vaginal mucus may be limited. To address these problems, the spermicidal activity of several chelating agents against human semen and their synergistic effect on the spermicidal activity of N-9 were evaluated using computer-assisted semen analysis and a cervical mucus penetration test. Carbopol 934P, chosen as a polymer base for dispersion of N-9 and chelating agent, was also evaluated for its potential spermicidal activity. Chelating agents, such as ethylenediaminetetraacetic acid (EDTA), ethylene bis(oxyethylenenitrilo)tetraacetic acid, and gramicidin, had spermicidal activity against human sperm at the tested concentration range and exerted spermicidal activity within mucus, impeding sperm penetration to the extended cervical space. A synergistic effect was shown between N-9 and EDTA on sperm motility. In dose-response curves, 0.1% EDTA significantly increased binding affinity constant and spermicidal potency of N-9 and reduced the concentration of N-9 at which 50% of the maximum response was observed from 144.5 to 66.4 (micrograms/mL). A synergistic effect was also shown between EDTA and carbopol 934P polymer on inhibition of sperm penetration through the cervical mucus. Therefore, EDTA can be used as a supplementary agent and potentiator for N-9. Development of a carbopol 934P-based drug delivery system for dual controlled release of N-9 in combination with chelating agents seems to be a promising approach for increasing the efficacy of fertility control.

Human in vitro fertilization in couples with unexplained infertility and a poor postcoital test

The results of in vitro fertilization (IVF) with the husband's semen were compared in 3 groups of fully investigated infertile couples. In those with tubal infertility (n = 43) 194 out of 273 (71.1%) oocytes were fertilized, at least 1 oocyte being fertilized in 42 of the 43 couples (97%). In couples with unexplained infertility and a 'good' postcoital test (PCT) (n = 9), 39 out of 64 (61.5%) oocytes were fertilized in 8 of the 9 (88%) couples. In couples with unexplained infertility and a 'poor positive' PCT despite normal semen analysis, 16 out of 44 (36.3%) oocytes were fertilized in 5 of the 6 (83%) couples. These results show a good correlation between in vivo sperm penetration of cervical mucus and human IVF in couples with unexplained infertility.

Follicle size by ultrasound versus cervical mucus quality: normal and abnormal patterns in spontaneous cycles

Ultrasound (US) has been demonstrated to be the method of choice for diagnosing luteinized unruptured follicle syndrome and to be a valuable adjuvant in the assessment of luteal phase defect. In this prospective study, the use of US with postcoital testing (PCT) is evaluated. Fifty control infertility patients were examined with serial US for follicle dynamics in conjunction with PCT. Standard curves for follicle dynamics versus cervical mucus quality (Insler score) were calculated. Eighteen patients referred for abnormal mucus underwent similar evaluation. Their follicle dynamics versus mucus quality were compared with those of the controls. The findings were: (1) there is a predictable relationship between follicle size and mucus quality, (2) the majority of patients with abnormal mucus have normal follicular dynamics, and (3) a minority of patients with abnormal mucus have either a narrow mucus window or abnormal follicular dynamics. In addition, US was found to be cost-effective in the overall fertility evaluation.

Efficacy of human menopausal gonadotropins as therapy for abnormal cervical mucus

Traditional therapies for abnormal cervical mucus, other than timed intrauterine insemination, are noteworthy for being ineffectual. Patients (n = 27) with documented abnormal Insler scores in repetitive cycles and failure to conceive with traditional treatments were screened with conjugated equine estrogens (CEE) for estrogen responsiveness of the cervix. Only 5 patients were found unresponsive. Seventeen patients with CEE-responsive cervices then were treated with human gonadotropins (hMG), initially 1 ampule days 5 to 11. If the mucus failed to improve, the hMG was increased to standard doses. Eight patients responded to 1 ampule hMG with improved mucus and conception. The remainder required 2 ampules hMG. In patient cycles with corrected cervical mucus, the viable fecundibility (fv) was 0.35. This is significantly higher than predicted for this population (fv = 0.09; P less than 0.01). In all, 14 of 17 patients conceived viable pregnancies during hMG treatment. It is concluded that graduated hMG is efficacious in treating patients with abnormal cervical mucus responsive to CEE. It is preferable to either in vitro fertilization or gamete intrafallopian transfer, based on both cost and efficacy for most patients.

Intracervical versus intrauterine insemination: correlation of outcome with antecedent postcoital testing

Thirty-four infertile women alternated cycles of intracervical insemination (ICI) with whole ejaculate homologous semen (mean, 3.2 cycles/patient) versus intrauterine insemination (IUI) with washed sperm (mean, 3.4 cycles/patient). Twenty of the 34 women had prior postcoital tests consistently demonstrating less than or equal to 3 motile sperm per high-powered field (HPF). Six of those 20 conceived during IUI cycles (30.0%); 0 conceived during ICI cycles (P = 0.06, Mantel-Haenszel chi-square test). The pregnancy rate per IUI cycle was 6/72 (8.3%), compared with 0/66 (0.0%) per ICI cycle, a statistically significant difference (P = 0.04, Fisher's exact chi-square test). Fourteen of 34 women had prior postcoital tests consistently demonstrating greater than or equal to 5 motile sperm per HPF. One of the 14 conceived during an IUI cycle (7.1%), and 2 conceived during ICI cycles (14.3%), a difference that was not significant. The pregnancy rate per IUI cycle was 1/42 (2.4%), compared with 2/42 (4.8%) per ICI cycle (not significant). IUI may be helpful in the management of infertility associated with relatively poor postcoital tests (less than or equal to 3 motile sperm per HPF) but not with relatively good postcoital tests (greater than or equal to 5 motile sperm per HPF).

Important semen parameters during postcoital testing

One hundred and sixty-two females who attended our infertility clinic were selected according to the quality of their cervical mucus. Only mucus of extremely high quality was used in the study to determine the influence of different semen parameters on the postcoital test results. All mucus samples were evaluated 8 h following coitus. The results of the postcoital tests were divided into group I (less than 7 spermatozoa per 400 X magnification) and group II (greater than 7 spermatozoa per 400 X magnification). The results of the statistical analysis indicated the order of importance of the different semen parameters during postcoital testing. By using the stepwise discriminant analyses, it was calculated that the sperm concentration and forward progression rate of the spermatozoa are discriminating factors between the two groups.

Human sperm velocity and postinsemination cervical mucus test in the evaluation of the infertile couple

Homologous artificial insemination (AIH) followed by postinsemination cervical mucus test (PIT) was performed in 100 couples in a prospective study to evaluate suspected cervical or male factor infertility. A portion of the ejaculate was submitted for standard semen analysis as well as turbidimetric analysis of sperm velocity. In a review of 333 cases evaluated for infertility, the average sperm velocity in a normal semen analysis was 96.5 mu/sec, for those with normal postcoital test (PCT) 96.6 mu/sec, and in those that established a pregnancy 91.6 mu/sec. These are significantly higher than the values obtained for abnormal semen analysis and abnormal PCT (64.6 and 63.6 mu/sec, respectively; p less than 0.001). Patients with normal PIT (WHO criteria for normal PCT consisting of greater than or equal to 7 motile sperm/hpf) had sperm velocity of 87 mu/sec compared to velocities of 46 mu/sec for abnormal PIT (p less than 0.001). Four of the five patients with abnormal PIT (in spite of normal semen analysis and normal cervical mucus) had sperm velocities less than 75 mu/sec. Likewise, all 8 patients who had normal PIT in spite of abnormal semen analysis had sperm velocities greater than 75 mu/sec, even though the sperm motility was below normal in 5 of them. Sperm velocity is a more sensitive indicator of sperm function when compared to standard semen analysis results.

Unexplained infertility

To recapitulate, four questions must be raised when the couple has been evaluated and found to be normal: (1) Was the infertility evaluation complete in terms of modern standards? (2) Were the results of studies and observations appropriately interpreted? (3) Has a factor which was considered within normal limits and compatible with fertility at the onset of the workup changed during the course of the evaluation? (4) How accessible for evaluation are processes necessary for conception which occur within the reproductive tract? Both members of the couple as well as the managing physician are frustrated and plagued by feelings of inadequacy when no positive findings can be identified during the course of an infertility evaluation. This situation obviously requires of the physician a combination of delicacy, patience, and considerable attention to each detail of the evaluation which has just been completed. The material herein was designed to raise suggestions for approaches to such couples when faced with the designation of "unexplained infertility."

Early conception in patients with untreated mild endometriosis

The purpose of this paper is to report the reproductive experience in 31 infertile patients with mild endometriosis who were not treated by surgery or medication. A series of 31 cases of laparoscopically diagnosed mild endometriosis were followed up without therapy for a period of 36 months. Ten patients received artificial insemination by donor (AID) because of male-related infertility; 21 patients had well-timed postcoital tests and monitored ovulation cycles. Life-table analysis of conceptions was used for presentation of the pregnancy rate. The group of patients whose husbands were azoospermic had a 90% pregnancy rate within 18 months, with a mean of 3.5 treatment cycles for pregnancy. The nonazoospermic couples had a 47.6% pregnancy rate within 18 months, with a mean of 7.2 monitored cycles for pregnancy. The calculated median delays for the series of patients who conceived were 1.9 cycles. The whole series (n = 31) of patients with mild endometriosis had an 8.3% monthly pregnancy rate within 18 months and a 61.2% cumulative pregnancy rate within 18 months. We have come to the conclusion that mild endometriosis does not interfere with female fertility, and patients with this extent of disease should not be treated for a trial period of at least 18 months as an alternative to more aggressive therapy.

Postcoital testing in women during menotropin therapy

The authors were interested in determining the predictive value of postcoital testing in women who undergo human menopausal gonadotropin (hMG) therapy for the induction of ovulation. Fifty consecutive patients were studied whose husbands had acceptable semen analyses; 24 of the patients conceived. Postcoital testing was done after hMG stimulation on the day human chorionic gonadotropins (hCG) were given or the day before. All but one patient had excellent cervical mucus quality. Sperm characteristics in cervical mucus were analyzed in regard to overall motility, number of active sperm per high-power field (HPF), and quality of movement. These data were correlated with outcome in terms of conception. A linear correlation could be shown between overall motility and pregnancy outcome once at least 40% motility was present; no pregnancy occurred in patients with 20% or less sperm motility. Once five or more active sperm/HPF were noted, the chance of pregnancy was about 60%; this chance was not increased with higher density rates. In all but one patient who conceived, sperm with maximum quality (+3 motility) were noted. Data were compiled in a postcoital score (range 0 to 12). Patients with a high score had a pregnancy rate of 70%, patients with an intermediate score, 23%, and none of the seven women with low scores conceived. Because menotropin therapy is costly, demanding, and potentially risky, it is suggested that one utilize results of postcoital testing as a guide in decisions about the continuation of such therapy.

The infertile patient. Guidelines for successful workup

The key to a successful infertility workup is to follow a protocol carefully and completely. After preliminary history taking and physical examination, tests are carried out systematically to investigate all possible ovulatory, cervical, tubal, and endometrial factors. A basal body temperature chart is essential for proper timing of tests, and a flow sheet helps keep track of results. Thorough evaluation of the man is also needed to identify possible causative factors.