Abstract PD7-07: Failure of goserelin to prevent chemotherapy-induced damage to ovarian reserve

Abstract

Abstract Objective The effectiveness of GnRH analogs (GnRHa) in preserving ovarian reserve and fertility against chemotherapy-induced damage is still being debated. Prior studies generally used menstruation as an outcome measure, which is an unreliable surrogate for fertility. Cyclophosphamide is one of the key components of most commonly utilized adjuvant and neo-adjuvant chemotherapy protocols in breast cancer. Ovarian reserve is made up of quiescent primordial follicles, which are irreversibly damaged by gonadotoxic chemotherapy agents such as cyclophosphamide (Cy) via the induction of double strand DNA breaks (DSBs) that trigger apoptotic oocyte death (Soleimani et al, Aging 2011). There is currently no data on whether GnRHa co-treatment would block chemo-induced primordial follicle DNA damage. We conducted this animal study to determine whether co-administration of a GnRHa would protect cyclophosphamide-induced primordial follicle death and DNA damage. If ovarian suppression by GnRHa does not protect chemotherapy-induced damage to ovarian reserve, then there would be no biological basis for utilizing this strategy for fertility preservation. Design Experimental animal study. Materials and Methods After unilateral oophorectomy, 4-week-old FVB mice received daily 200 mg/kg Cy injections either alone for 3 days (n=4) or with 250 μg/kg Goserelin co-treatment (n=4) starting 3 days before and continuing the duration of chemotherapy. The remaining ovary was recovered at the end of chemotherapy for analysis. Ovaries were fixed and serially sectioned at 5 μm, and every 10th section was analyzed. Primordial (pdf) density, oocyte DSBs (by γH2AX) and apoptotic cell death pathway activation (AC3) were determined by immunostaining and compared between the pre- and post-chemo ovaries of each mice in a paired analysis, as well as between the 2 groups post-chemo. Results Results are summarized in table-1. In both the Cy-only and Cy+GnRHa groups, pdf densities declined significantly compared to pre-chemo (p= 0.003). However, there was no difference between the post-chemo pdf densities of the two groups. Likewise, both Cy and Cy+GnRHa resulted in significantly increased oocyte DNA damage and apoptotic death (p<0.01) compared to baseline readings. However, post-chemo incidence of oocyte DNA damage and apoptotic death were similar between the Cy and Cy+GnRHa groups (p= 0.69 and 0.78, respectively). Impact of GnRHa on Chemo-Induced Ovarian Damage Pre-chemoCyCy+GnRHaCy vs. Pre-chemoCy+GnRHa vs. Pre-chemoCy vs. Cy+GnRHaPdf Density (/mm3)1,300±25.8685±128.4640±121.3<0.01<0.010.8γ-H2AX+ Pdf (%)12.3±0.0871.2±6.975±5.8<0.01<0.010.69AC3+ Pdf (%)053.6±0.638.1±0.06<0.01<0.010.78Pdf: primordial follicle. Data are presented as mean ±SE. P <0.05considered as statistically significant. Conclusions This animal study provides the first direct histologic and molecular evidence that GnRHa co-treatment does not prevent chemotherapy-induced damage to ovarian reserve including potentially mutagenic DNA DSBs in oocytes. Taken together with the recent clinical data utilizing more reliable ovarian reserve markers such as the anti-mullerian hormone (Demeestere et al, J Clin Oncol, 2016), ovarian suppression via GnRHa should not be recommended for the protection of ovarian reserve.(Supported by NIH RO1 HD053112). Citation Format: Oktay K, Taylan E, Sugishita Y, Kawahara T, Suzuki N. Failure of goserelin to prevent chemotherapy-induced damage to ovarian reserve [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr PD7-07.