Both in vivo FSH depletion and follicular exposure to Gonadotrophin-releasing hormone analogues in vitro are not effective to prevent follicular depletion during chemotherapy in mice

Maximizing ovarian function and fertility following chemotherapy in premenopausal patients: Is there a role for ovarian suppression?

As more premenopausal patients undergo fertility preserving cancer treatments, there is an increased need for fertility counseling and ovarian sparing strategies. Many patients receive gonadotoxic chemotherapeutic agents which can put them at risk of primary ovarian insufficiency or profoundly diminished ovarian reserve. Traditionally, estradiol and follicle stimulating hormone (FSH) values have been used to evaluate ovarian function but more recently, reproductive endocrinologists have been proponents of anti-mullerian hormone (AMH) as a validated measure of ovarian potential. While the gold standard for fertility preservation remains oocyte cryopreservation, data suggest there may be additional interventions that can mitigate the gonadotoxic effects of chemotherapeutic agents. The main objectives of this focused review were to quantify the risk of primary ovarian failure associated with the most common chemotherapies used in treatment of gynecologic cancers and to evaluate and recommend potential interventions to mitigate toxic effects on ovarian function. Chemotherapeutic agents can cause direct loss of oocytes and primordial follicles as well as stromal and vascular atrophy and the extent is dependent upon mechanism of action and age of the patient. The risk of ovarian failure is the highest with alkylating agents (42.2 %), anthracyclines (<10-34 % in patients under 40 years versus 98 % in patients aged 40-49), taxanes (57.1 %) and platinum agents (50 %). Multiple trials demonstrate that gonadotropin releasing hormone (GnRH) agonists, when administered concurrently with chemotherapy, may have protective effects, with more patients experiencing resumption of a regular menstruation pattern and recovering ovarian function more quickly post-treatment. Premenopausal patients receiving chemotherapy for the treatment of gynecologic cancers should receive adequate counseling on the potential adverse effects on their fertility. Although oocyte cryopreservation remains the gold standard for fertility preservation, there is some evidence to suggest that GNRH agonists could help maintain and preserve ovarian function and should be considered.

Let-7a mimic transfection reduces chemotherapy-induced damage in a mouse ovarian transplantation model

Pharmacological approaches offer a non-invasive and promising option for fertility preservation in young female cancer patients undergoing gonadotoxic therapy. The GnRH-agonists are the only clinically available drugs in this indication, but their use and mechanisms of protection are still controversial. Recently, we have investigated new targeted drugs based on microRNA (miRNA) replacement therapy, and have identified the let-7a miRNA as candidate for fertility preservation strategies. Here, the effect of let-7a replacement during chemotherapy exposure on follicular growth and oocyte maturation capacity was investigated using a mouse ovarian-kidney transplantation model. Newborn mouse ovaries were cultured under different conditions; control, chemotherapy exposure (4-hydroperoxycyclophosphamide, 4-HC), and co-treatment with 4-HC and let-7a mimic transfection (4-HC + let-7a). The ovaries were then transplanted under the kidney capsule of recipient mice and follicular growth, survival, and oocyte in vitro maturation were assessed after 3 weeks. The results showed that the follicular pool was highest in the control group but higher in the 4-HC + let-7a group than the 4-HC group. DNA-damage/apoptosis ratios were higher in all 4-HC-exposed groups compared to control but were reduced in the 4-HC + let-7a group. In addition, the post-transplantation oocyte in vitro maturation rate was higher in the 4-HC + let-7a group compared to the 4-HC group, suggesting better oocyte quality. These results provide new information regarding the beneficial effects of let-7a replacement against chemotherapy-induced ovarian damage and open new perspectives for future in vivo applications.

Single-cell transcriptome and cell-specific network analysis reveal the reparative effect of neurotrophin-4 in preantral follicles grown in vitro

BACKGROUND

In-vitro-grow (IVG) of preantral follicles is essential for female fertility preservation, while practical approach for improvement is far from being explored. Studies have indicated that neurotrophin-4 (NT-4) is preferentially expressed in human preantral follicles and may be crucial to preantral follicle growth.

METHODS

We observed the location and expression of Tropomyosin-related kinase B (TRKB) in human and mouse ovaries with immunofluorescence and Western blot, and the relation between oocyte maturation and NT-4 level in follicular fluid (FF). Mice model was applied to investigate the effect of NT-4 on preantral follicle IVG. Single-cell RNA sequencing of oocyte combined with cell-specific network analysis was conducted to uncover the underlying mechanism of effect.

RESULTS

We reported the dynamic location of TRKB in human and mouse ovaries, and a positive relationship between human oocyte maturation and NT-4 level in FF. Improving effect of NT-4 was observed on mice preantral follicle IVG, including follicle development and oocyte maturation. Transcriptome analysis showed that the reparative effect of NT-4 on oocyte maturation might be mediated by regulation of PI3K-Akt signaling and subsequent organization of F-actin. Suppression of advanced stimulated complement system in granulosa cells might contribute to the improvement. Cell-specific network analysis revealed NT-4 may recover the inflammation damage induced by abnormal lipid metabolism in IVG.

CONCLUSIONS

Our data suggest that NT-4 is involved in ovarian physiology and may improve the efficiency of preantral follicle IVG for fertility preservation.

The cyto-protective effects of LH on ovarian reserve and female fertility during exposure to gonadotoxic alkylating agents in an adult mouse model

STUDY QUESTION

Does LH protect mouse oocytes and female fertility from alkylating chemotherapy?

SUMMARY ANSWER

LH treatment before and during chemotherapy prevents detrimental effects on follicles and reproductive lifespan.

WHAT IS KNOWN ALREADY

Chemotherapies can damage the ovary, resulting in premature ovarian failure and reduced fertility in cancer survivors. LH was recently suggested to protect prepubertal mouse follicles from chemotoxic effects of cisplatin treatment.

STUDY DESIGN, SIZE, DURATION

This experimental study investigated LH effects on primordial follicles exposed to chemotherapy. Seven-week-old CD-1 female mice were randomly allocated to four experimental groups: Control (n = 13), chemotherapy (ChT, n = 15), ChT+LH-1x (n = 15), and ChT+LH-5x (n = 8). To induce primary ovarian insufficiency (POI), animals in the ChT and ChT+LH groups were intraperitoneally injected with 120 mg/kg of cyclophosphamide and 12 mg/kg of busulfan, while control mice received vehicle. For LH treatment, the ChT+LH-1x and ChT+LH-5x animals received a 1 or 5 IU LH dose, respectively, before chemotherapy, then a second LH injection administered with chemotherapy 24 h later. Then, two animals/group were euthanized at 12 and 24 h to investigate the early ovarian response to LH, while remaining mice were housed for 30 days to evaluate short- and long-term reproductive outcomes. The effects of LH and chemotherapy on growing-stage follicles were analyzed in a parallel experiment. Seven-week-old NOD-SCID female mice were allocated to control (n = 5), ChT (n = 5), and ChT+LH-1x (n = 6) groups. Animals were treated as described above, but maintained for 7 days before reproductive assessment.

PARTICIPANTS/MATERIALS, SETTING, METHODS

In the first experiment, follicular damage (phosphorylated H2AX histone (γH2AX) staining and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) assay), apoptotic biomarkers (western blot), and DNA repair pathways (western blot and RT-qPCR) were assessed in ovaries collected at 12 and 24 h to determine early ovarian responses to LH. Thirty days after treatments, remaining mice were stimulated (10 IU of pregnant mare serum gonadotropin (PMSG) and 10 IU of hCG) and mated to collect ovaries, oocytes, and embryos. Histological analysis was performed on ovarian samples to investigate follicular populations and stromal status, and meiotic spindle and chromosome alignment was measured in oocytes by confocal microscopy. Long-term effects were monitored by assessing pregnancy rate and litter size during six consecutive breeding attempts. In the second experiment, mice were stimulated and mated 7 days after treatments and ovaries, oocytes, and embryos were collected. Follicular numbers, follicular protection (DNA damage and apoptosis by H2AX staining and TUNEL assay, respectively), and ovarian stroma were assessed. Oocyte quality was determined by confocal analysis.

MAIN RESULTS AND THE ROLE OF CHANCE

LH treatment was sufficient to preserve ovarian reserve and follicular development, avoid atresia, and restore ovulation and meiotic spindle configuration in mature oocytes exposed at the primordial stage. LH improved the cumulative pregnancy rate and litter size in six consecutive breeding rounds, confirming the potential of LH treatment to preserve fertility. This protective effect appeared to be mediated by an enhanced early DNA repair response, via homologous recombination, and generation of anti-apoptotic signals in the ovary a few hours after injury with chemotherapy. This response ameliorated the chemotherapy-induced increase in DNA-damaged oocytes and apoptotic granulosa cells. LH treatment also protected growing follicles from chemotherapy. LH reversed the chemotherapy-induced depletion of primordial and primary follicular subpopulations, reduced oocyte DNA damage and granulosa cell apoptosis, restored mature oocyte cohort size, and improved meiotic spindle properties.

LARGE SCALE DATA

N/A.

LIMITATIONS, REASONS FOR CAUTION

This was a preliminary study performed with mouse ovarian samples. Therefore, preclinical research with human samples is required for validation.

WIDER IMPLICATIONS OF THE FINDINGS

The current study tested if LH could protect the adult mouse ovarian reserve and reproductive lifespan from alkylating chemotherapy. These findings highlight the therapeutic potential of LH as a complementary non-surgical strategy for preserving fertility in female cancer patients.

STUDY FUNDING/COMPETING INTEREST(S)

This study was supported by grants from the Regional Valencian Ministry of Education (PROMETEO/2018/137), the Spanish Ministry of Science and Innovation (CP19/00141), and the Spanish Ministry of Education, Culture and Sports (FPU16/05264). The authors declare no conflict of interest.

Metformin: a novel promising option for fertility preservation during cyclophosphamide-based chemotherapy

Cyclophosphamide (CP) could cause severe gonadotoxicity via imbalanced activation of primordial follicles through PI3K/AKT/mTOR activation. Whether metformin, a widely prescribed anti-diabetes agent with mTOR inhibitory effect, could preserve ovarian function against CP toxicity is unknown. Female C57BL/6 mice were randomized into seven groups (n = 11), including control, CP-alone, CP + metformin, CP + sirolimus or everolimus, metformin-alone and sirolimus-alone groups. The duration of pharmaceutical treatment was 4 weeks. CP treatment significantly impaired ovarian function and fertility in mice. CP + metformin treatment significantly attenuated the gonadotoxicity comparing to CP-alone treatment (primordial follicle count: 17.6 ± 4.2 versus 10.3 ± 2.7 follicles/high-power field; P = 0.027). CP + metformin treatment also tended to increase antral follicular count (5.4 ± 1.1 versus 2.5 ± 1.6 follicles/section), serum AMH levels (4.6 ± 1.2 versus 2.0 ± 0.8 ng/ml) and the litter size (4.2 ± 1.3 versus 1.5 ± 1.0 mice per pregnancy), compared with CP-alone group. Expression of phospho-mTOR and the number of TUNEL-positive granulosa cells increased after CP treatment and decreased in the CP + metformin groups, suggesting the mTOR inhibitory and anti-apoptotic effects of metformin. In in-vitro granulosa cell experiments, the anti-apoptotic effect of metformin was blocked after inhibiting p53 or p21 function, and the expression of p53 mRNA was blocked with AMPK inhibitor, suggesting that the anti-apoptotic effect was AMPK/p53/p21-mediated. In conclusion, concurrent metformin treatment during CP therapy could significantly preserve ovarian function and fertility and could be a promising novel fertility preserving agent during chemotherapy. The relatively acceptable cost and well-established long-term safety profiles of this old drug might prompt its further clinical application at a faster pace.

Gonadotropin Releasing Hormone Agonists Have an Anti-apoptotic Effect on Cumulus Cells

Background: Ovaries are sensitive to chemotherapy, which may lead to early depletion of primordial follicle reserve. One strategy for gonadal function preservation is temporary ovarian suppression with Gonadotropin Releasing Hormone agonists (GnRHa) during chemotherapy. To date, GnRHa protective mechanism of action remains not fully elucidated. Methods: We collected 260 immature cumulus cell-oocyte complexes (COC) from 111 women < 38 years old, with a normal ovarian reserve. The COC were randomly assigned to the following groups: (a) control; culture with the addition of (b) GnRHa; (c) cyclophosphamide; (d) cyclophosphamide plus GnRHa. After in vitro treatments, RNA and proteins were extracted from oocytes and cumulus cells (CC), separately. Potential effects of drugs were evaluated on GnRH receptors, apoptosis pathways, ceramide pathway, and glutathione synthesis by quantitative PCR and, whenever possible, by Western blot. Results: Cyclophosphamide triggered activation of the extrinsic pathway of apoptosis mediated by BAX in CC. The co-administration of GnRHa inhibited the apoptosis pathway in CC. According to our model, the GnRHa does not directly act on oocytes, which do not express GnRH receptors. Moreover, glutathione synthesis was decreased after GnRHa treatment both in CC and oocytes. Conclusion: Our data suggest that the protective mechanisms induced by GnRHa is mediated by an anti-apoptotic effect on CC.

Consequences of chemotherapeutic agents on primordial follicles and future clinical applications

The ovarian reserve is necessary for female fertility and endocrine health. Commonly used cancer therapies diminish the ovarian reserve, thus, resulting in primary ovarian insufficiency, which clinically presents as infertility and endocrine dysfunction. Prepubertal children who have undergone cancer therapies often experience delayed puberty or cannot initiate puberty and require endocrine support to maintain a normal life. Thus, developing an effective intervention to prevent loss of the ovarian reserve is an unmet need for these cancer patients. The selection of adjuvant therapies to protect the ovarian reserve against cancer therapies underlies the mechanism of loss of primordial follicles (PFs). Several theories have been proposed to explain the loss of PFs. The "burn out" theory postulates that chemotherapeutic agents activate dormant PFs through an activation pathway. Another theory posits that chemotherapeutic agents destroy PFs through an "apoptotic pathway" due to high sensitivity to DNA damage. However, the mechanisms causing loss of the ovarian reserve remains largely speculative. Here, we review current literature in this area and consider the mechanisms of how gonadotoxic therapies deplete PFs in the ovarian reserve.

The Impact of Chemotherapy on the Ovaries: Molecular Aspects and the Prevention of Ovarian Damage

Cancer treatment, such as chemotherapy, induces early ovarian follicular depletion and subsequent infertility. In order to protect gametes from the gonadotoxic effects of chemotherapy, several fertility preservation techniques—such as oocyte or embryo cryopreservation with or without ovarian stimulation, or cryopreservation of the ovarian cortex—should be considered. However, these methods may be difficult to perform, and the future use of cryopreserved germ cells remains uncertain. Therefore, improving the methods currently available and developing new strategies to preserve fertility represent major challenges in the area of oncofertility. Animal and ovarian culture models have been used to decipher the effects of different cytotoxic agents on ovarian function and several theories regarding chemotherapy gonadotoxicity have been raised. For example, cytotoxic agents might (i) have a direct detrimental effect on the DNA of primordial follicles constituting the ovarian reserve and induce apoptosis; (ii) induce a massive growth of dormant follicles, which are then destroyed; or (ii) induce vascular ovarian damage. Thanks to improvements in the understanding of the mechanisms involved, a large number of studies have been carried out to develop molecules limiting the negative impact of chemotherapy on the ovaries.

Fertility preservation in gynecologic cancers

An increasing number of women in modern societies are delaying childbearing beyond the age of 35, and gynecologic cancers affect a significant proportion of reproductive age women who wish to preserve fertility for a future chance of childbearing. As a result, providing treatment options for fertility preservation in women with gynecologic cancer has become a crucial component of cancer survivorship care. In this review article, we discussed the current knowledge on fertility-sparing surgical approaches, as well as assisted reproductive technologies that can be utilized to preserve reproductive potential in women with cervical, endometrial, and ovarian cancer. A brief section on fertility preservation in pediatric gynecologic malignancies is also provided.

Ovarian Follicle Depletion Induced by Chemotherapy and the Investigational Stages of Potential Fertility-Protective Treatments-A Review

Ovarian follicle pool depletion, infertility, and premature menopause are all known sequelae of cancer treatment that negatively impact the quality of life of young cancer survivors. The mechanisms involved in this undesired iatrogenic ovarian damage have been intensively studied, but many of them remain unclear. Several chemotherapeutic drugs have been shown to induce direct and indirect DNA-damage and/or cellular stress, which are often followed by apoptosis and/or autophagy. Damage to the ovarian micro-vessel network induced by chemotherapeutic agents also seems to contribute to ovarian dysfunction. Another proposed mechanism behind ovarian follicle pool depletion is the overactivation of primordial follicles from the quiescent pool; however, current experimental data are inconsistent regarding these effects. There is great interest in characterizing the mechanisms involved in ovarian damage because this might lead to the identification of potentially protective substances as possible future therapeutics. Research in this field is still at an experimental stage, and further investigations are needed to develop effective and individualized treatments for clinical application. This review provides an overview of the current knowledge and the proposed hypothesis behind chemotherapy-induced ovarian damage, as well as current knowledge on possible co-treatments that might protect the ovary and the follicles from such damages.

Adjuvant gonadotropin-releasing hormone analogues for the prevention of chemotherapy-induced premature ovarian failure in premenopausal women

BACKGROUND

This is an update of the original review published in the Cochrane Database of Systematic Reviews 2011, Issue 11, and updated in 2015, Issue 4.Chemotherapy has significantly improved prognosis for women with malignant and some non-malignant conditions. This treatment, however, is associated with ovarian toxicity. The use of gonadotropin-releasing hormone (GnRH) analogues, both agonists and antagonists, may have a protective effect on the ovaries. The primary mechanism of action of GnRH analogues is to suppress the gonadotropin levels to simulate pre-pubertal hormonal milieu and subsequently prevent primordial follicles from maturation and therefore decrease the number of follicles that are more vulnerable to chemotherapy.

OBJECTIVES

To assess the efficacy and safety of GnRH analogues given before or in parallel to chemotherapy to prevent chemotherapy-related ovarian damage in premenopausal women with malignant or non-malignant conditions.

SEARCH METHODS

The search was run for the original review in July 2011, and for the first update in July 2014. For this update we searched the following databases in November 2018: the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, and the Chinese Biomedicine Database (CBM).

SELECTION CRITERIA

Randomised controlled trials (RCTs), in all languages, which examined the effect of GnRH analogues for chemotherapy-induced ovarian failure in premenopausal women, were eligible for inclusion in the review.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data and assessed trial quality using the Cochrane 'Risk of bias' tool. We analysed binary data using risk ratios (RRs) with 95% confidence intervals (CI) and for continuous data, we used the standardized mean difference (SMD) to combine trials. We applied the random-effects model in our analyses. We used the GRADE approach to produce a 'Summary of findings' table for our main outcomes of interest.

MAIN RESULTS

We included 12 RCTs involving 1369 women between the ages of 12 and 51.1 years. Participants were diagnosed with breast malignancy, ovarian malignancy, or Hodgkin's lymphoma, and most of them received alkylating, or platinum complexes, based chemotherapy. The included studies were funded by a university (n = 1), research centres (n = 4), and pharmaceutical companies (n = 1). Trials were at high or unclear risk of bias.Comparison 1: GnRH agonist plus chemotherapy versus chemotherapy aloneThe incidence of menstruation recovery or maintenance was 178 of 239 (74.5%) in the GnRH agonist group and 110 of 221 (50.0%) in the control group during a follow-up period no longer than 12 months (RR 1.60, 95% CI 1.14 to 2.24; 5 studies, 460 participants; I² = 79%; low-certainty evidence), with an overall effect favouring treatment with GnRH agonist (P = 0.006). However, we observed no difference during a follow-up period longer than 12 months between these two groups (P = 0.24). In the GnRH agonist group, 326 of 447 participants had menstruation recovery or maintenance (72.9%) in comparison to the control group, in which 276 of 422 participants had menstruation recovery or maintenance (65.4%) during a follow-up period longer than 12 months (RR 1.08, 95% CI 0.95 to 1.22; 8 studies, 869 participants; I² = 56%; low-certainty evidence).The incidence of premature ovarian failure was 43 of 401 (10.7%) in the GnRH agonist group and 96 of 379 (25.3%) in the control group (RR 0.44, 95% CI 0.31 to 0.61; 4 studies, 780 participants; I² = 0%; moderate-certainty evidence), with an overall effect favouring treatment with GnRH agonist (P < 0.00001).The incidence of pregnancy was 32 of 356 (9.0%) in the GnRH agonist group and 22 of 347 (6.3%) in the control group (RR 1.59, 95% CI 0.93 to 2.70; 7 studies, 703 participants; I² = 0%; low-certainty evidence), with no difference between groups (P = 0.09). However, we are cautious about this conclusion because there were insufficient data about whether the participants intended to become pregnant.The incidence of ovulation was 29 of 47 (61.7%) in the GnRH agonist group and 12 of 48 (25.0%) in the control group (RR 2.47, 95% CI 1.43 to 4.26; 2 studies, 95 participants; I² = 0%; low-certainty evidence) with an overall effect favouring treatment with GnRH (P = 0.001).The most common adverse effects of GnRH analogues included hot flushes, vaginal dryness, urogenital symptoms, and mood swings. The pooled analysis of safety data showed no difference in adverse effects between GnRH agonist group and control group.Comparison 2: GnRH agonist-antagonist cotreatment plus chemotherapy versus chemotherapy aloneOnly one RCT discussed GnRH agonist-antagonist cotreatment. The limited evidence showed the incidence of menstruation recovery or maintenance was 20 of 25 (80%) in both cotreatment group and control group during a 12-month follow-up period (RR 1.00, 95% CI 0.76 to 1.32; 50 participants; very low-certainty evidence), with no difference between groups (P = 1.00). In the cotreatment group, 13 of 25 participants had menstruation recovery or maintenance (52.0%) in comparison to the control group, in which 14 of 25 participants had menstruation recovery or maintenance (56.0%) during a follow-up period longer than 12 months (RR 0.93, 95% CI 0.56 to 1.55; 50 participants; very low-certainty evidence), with no difference between groups (P = 0.78). The incidence of pregnancy was 1 of 25 (4.0%) in the cotreatment group and 0 of 25 (0%) in the control group (RR 3.00, 95% CI 0.13 to 70.30; 50 participants; very low-certainty evidence), with no difference between groups (P = 0.49).

AUTHORS' CONCLUSIONS

GnRH agonist appears to be effective in protecting the ovaries during chemotherapy, in terms of maintenance and resumption of menstruation, treatment-related premature ovarian failure and ovulation. Evidence for protection of fertility was insufficient and needs further investigation. Evidence was also insufficient to assess the effect of GnRH agonist and GnRH antagonist cotreatment on ovarian protection against chemotherapy. The included studies differed in some important aspects of design, and most of these studies had no age-determined subgroup analysis. Large and well-designed RCTs with longer follow-up duration should be conducted to clarify the effects of GnRH analogues in preventing chemotherapy-induced ovarian failure, especially on different age groups or different chemotherapy regimens. Furthermore, studies should address the effects on pregnancy rates and anti-tumour therapy.

Ovarian protection with gonadotropin-releasing hormone agonists during chemotherapy in cancer patients: From biological evidence to clinical application

Survivorship issues are an area of crucial importance to be addressed as early as possible by all health care providers dealing with cancer patients. In women diagnosed during their reproductive years, the possible occurrence of chemotherapy-induced premature ovarian insufficiency (POI) is of particular concern being associated with important menopause-related symptoms, psychosocial issues as well as infertility. Temporary ovarian suppression by administering a gonadotropin-releasing hormone agonist (GnRHa) during chemotherapy has been studied to reduce the gonadotoxic impact of chemotherapy thus diminishing the chance of developing POI. Despite more than 30 years of research in both preclinical and clinical settings, the performance of this strategy has remained highly debated until recently. In particular, the potential mechanisms of action for the protective effects of GnRHa during chemotherapy are still not clearly identified. Nevertheless, important novel research efforts in the field have better elucidated the role of this option that is now endorsed for clinical use by several guidelines. This manuscript aims at providing an extensive overview of the literature on the use of temporary ovarian suppression with GnRHa during chemotherapy in cancer patients by addressing its biological rationale, the available preclinical and clinical evidence as well as the still existing grey zones in this field that future research efforts should address.