Oral Presentation ESA-SRB 2023 in conjunction with ENSA

PUMA blockade protects oocytes from chemotherapy-induced depletion (#158)

Lauren R Alesi 1 , Roseanne Rosario 2 , Amy L Winship 1 , Jessica M Stringer 1 , Richard A Anderson 2 , Karla J Hutt 1
  1. Department of Anatomy & Developmental Biology, Monash Biomedicine Discovery Institute, Monash University, Clayton, VIC, Australia
  2. MRC Centre for Reproductive Health, Queen’s Medical Research Institute, University of Edinburgh, Edinburgh, United Kingdom

Irreversible ovarian damage and permanent depletion of oocytes are devastating side effects of chemotherapy, often leaving female cancer survivors infertile and at risk of premature menopause. Unfortunately, current fertility preservation options have significant drawbacks, with no strategies available to protect both fertility and long-term endocrine function1. PUMA, an apoptotic protein, triggers oocyte death following exposure to DNA-damaging insults, like chemotherapy2. In fact, genetic loss of PUMA preserves fertility post-chemotherapy without compromising offspring health3. Excitingly, a small-molecule PUMA inhibitor (PUMAi) is now available, making PUMA blockade for fertility preservation a real therapeutic possibility.

To assess whether PUMAi can prevent oocyte apoptosis post-chemotherapy, postnatal day 7 C57BL6/J mouse ovaries (n=6/group) were cultured ex vivo for 24 hours with the cyclophosphamide metabolite 4-HC (8µM) ± PUMAi (200µM). Similarly, human ovarian cortical pieces (n=5 patients) were cultured in vitro with 4-HC (2µM) ± PUMAi (200µM). Lastly, adult mice (n=6/group) received 10mg/kg PUMAi 2h before and 20h after 150mg/kg cyclophosphamide in vivo. This regimen was based on a previous study where PUMAi prevented intestinal stem cell apoptosis post-chemotherapy4.

Whilst 4-HC alone depleted primordial follicles by 87% (p<0.0001) in mice ex vivo, PUMAi rescued primordial follicles by 40% (p<0.01). Although 4-HC alone decreased the proportion of healthy primordial follicles (p<0.0001) in human ovarian tissue in vitro, PUMAi treatment restored this (p<0.05). In mice in vivo, cyclophosphamide alone reduced primordial follicles by 75% (p<0.01). Remarkably however, PUMAi rescued 50% of primordial follicles post-cyclophosphamide (p<0.05). This is extremely promising, as partial protection of just 12% of follicles in genetic PUMA knockout models sustained female fertility3,5.

These data demonstrate that PUMA blockade is a promising avenue for fertility preservation prior to chemotherapy treatment. Further studies are already underway to ensure that PUMAi does not impact the anti-tumour efficacy of chemotherapy and determine whether oocyte quality is also preserved post-treatment.

  1. Alesi LR, Nguyen Q-N, Stringer JM, Winship AL & Hutt KJ 2023. The future of fertility preservation for women treated with chemotherapy. Reproduction & Fertility, 4, e220123.
  2. Nguyen QN, Zerafa N, Liew SH, Findlay JK, Hickey M & Hutt KJ 2019. Cisplatin- and cyclophosphamide-induced primordial follicle depletion is caused by direct damage to oocytes. Molecular Human Reproduction, 25, 433-444.
  3. Nguyen QN, Zerafa N, Liew SH, Morgan FH, Strasser A, Scott CL, Findlay JK, Hickey M & Hutt KJ 2018. Loss of puma protects the ovarian reserve during DNA-damaging chemotherapy and preserves fertility. Cell Death & Disease, 9, 618.
  4. Leibowitz BJ, Yang L, Wei L, Buchanan ME, Rachid M, Parise RA, Beumer JH, Eiseman JL, Schoen RE, Zhang L & Yu J 2018. Targeting p53-dependent stem cell loss for intestinal chemoprotection. Science Translational Medicine, 10.
  5. Kerr JB, Hutt KJ, Michalak EM, Cook M, Vandenberg CJ, Liew SH, Bouillet P, Mills A, Scott CL, Findlay JK & Strasser A 2012. DNA damage-induced primordial follicle oocyte apoptosis and loss of fertility require TAp63-mediated induction of Puma and Noxa. Molecular Cell, 48, 343-352.