Increased chemotherapy-induced ovarian reserve loss in women with germline BRCA mutations due to oocyte deoxyribonucleic acid double strand break repair deficiency

Abstract

Objective: To assess whether woman who have BRCA mutations (WBM) experience more declines in ovarian reserve after chemotherapy treatment, as it induces oocyte death by deoxyribonucleic acid (DNA) damage, and BRCA mutations result in DNA damage repair deficiency.

Design: Longitudinal cohort study.

Setting: Academic centers.

Patient(s): The 108 evaluable women with breast cancer were stratified into those never tested (negative family history; n = 35) and those negative (n = 59) or positive (n = 14) for a pathogenic BRCA mutation.

Intervention(s): Sera were longitudinally obtained before and 12-24 months after chemotherapy treatment, assayed for antimüllerian hormone (AMH), and adjusted for age at sample collection.

Main outcome measure(s): Ovarian recovery, defined as the geometric mean of the after chemotherapy age-adjusted AMH levels compared with baseline levels.

Result(s): Compared with the controls, the before chemotherapy treatment AMH levels were 24% and 34% lower in those negative or positive for BRCA mutations, consistent with accelerated ovarian aging in WBM. The WBM had a threefold difference in AMH recovery after chemotherapy treatment (1.6%), when compared with BRCA negative (3.7%) and untested/low risk controls (5.2%). Limiting the analysis to the most common regimen, doxorubicin and cyclophosphamide followed by paclitaxel, showed similar results. These findings were mechanistically confirmed in an in vitro mouse oocyte BRCA knockdown bioassay, which showed that BRCA deficiency results in increased oocyte susceptibility to doxorubicin.

Conclusion(s): Women who have pathogenic BRCA mutations are more likely to lose ovarian reserve after chemotherapy treatment, suggesting an emphasis on fertility preservation. Furthermore, our findings generate the hypothesis that DNA repair deficiency is a shared mechanism between aging, infertility, and cancer.

Clinical trial registration number: NCT00823654.

Keywords: BRCA; chemotherapy; fertility preservation; ovarian insufficiency; ovarian reserve.

Copyright © 2020 American Society for Reproductive Medicine. Published by Elsevier Inc. All rights reserved.

Figures

FIGURE 1

Patient selection flow chart. From the parent study, 43 women did not qualify because they did not follow up after the initial encounter or received tamoxifen only. In the remaining 164 with at least one follow up, 19 did not have a sample 12–24 months after chemotherapy, 16 had a very low baseline AMH, and 21 were aged ≥43 years at baseline. The remaining 108 women were eligible to participate. Oktay. BRCA and chemotherapy-induced ovarian damage. Fertil Steril 2020.

FIGURE 2

Adjusted baseline antiMüllerian hormone (AMH) and ovarian recovery in women with breast cancer after receiving gonadotoxic chemotherapy, as defined by the geometric mean AMH adjusted levels at 12–24 months, stratified by BRCA mutation testing status. (A) Each woman’s AMH level was divided by the expected level based on her age at baseline testing. The expected value in the not tested group that were used for the regression analysis will, by definition, have an expected geometric mean ratio of 1.00 (dotted line). The solid horizontal lines indicate the geometric mean values for not tested and negative controls and the BRCA mutation positive group (1.00, 0.76, and 0.66). Analysis of variance with a linear contrast (−1, 0, 1) showed that these differences approached statistical significance (P = .07). (B) 108 women with all included chemotherapy regimens. Each woman’s AMH levels at 12, 18, and 24 months (when available) were divided by the expected level based on her age at sample collection and plotted on the vertical logarithmic axis. The solid horizontal lines indicate the geometric mean values for the not tested and negative controls and the BRCA mutation positive group (3.7%, 5.2%, and 1.6%). The dashed line at 4.6% shows the geometric mean for the not tested and BRCA negative groups combined, which is significantly different from the recovery in women with an identified deleterious BRCA1 and/or BRCA2 mutation (two-group analysis of variance, F = 4.89, P = .03). (C) Same data with restriction to doxorubicin cyclophosphamide + paclitaxel treatment, reducing the numbers from 108–83. The solid horizontal lines indicate the geometric mean values for the not tested and negative controls and the BRCA positive group (3.2%, 4.7%, and 1.3%). The dashed line shows the geometric mean for the not tested and negative groups combined (4.1%), which is significantly different from the recovery in women with an identified deleterious BRCA1 and/or BRCA2 mutation (two-group analysis of variance, F = 4.2, P = .04). Oktay. BRCA and chemotherapy-induced ovarian damage. Fertil Steril 2020.

FIGURE 3

BRCA1 deficiency results in oocyte sensitivity to chemotherapy in a mouse bioassay. FVB mice oocytes were treated with doxorubicin (100 μg/mL) for 1 hour after sham, scrambled small interfering ribonucleic acid (siRNA), or siRNA microinjection to silence BRCA1 in the oocytes. Oocyte survival was assessed 8 hours later. (A) Significant increase (P = .003) in the percentage of oocyte death was observed in the BRCA silenced group (128 oocytes from 8 mice) when compared to the sham (110 oocytes from 8 mice) and scrambled-siRNA-injected group (118 oocytes from 8 mice). Representative differential interference contrast images of the sham (B), scrambled siRNA (C) and BRCA1 siRNA-treated (D) oocytes are shown after doxorubicin exposure. White arrows point to representative viable and red arrows point to nonviable oocytes. Oktay. BRCA and chemotherapy-induced ovarian damage. Fertil Steril 2020.