Cancer therapies frequently cause irreversible ovarian damage, depleting the finite reserve of oocytes and leading to infertility and premature menopause in female survivors. This presents a major health challenge for the increasing number of young women surviving cancer, as no current strategies protect both fertility and long-term health post-treatment1. Our previous landmark studies revealed chemotherapy directly damages oocyte DNA and induces apoptosis2, with PUMA identified as the key mediator of oocyte loss3. Notably, our recent work presented at ESA-SRB-ANZBMS-2024 demonstrated that small molecule PUMA inhibition robustly protects oocytes in preclinical mouse and human models. Here, we assessed the impacts of PUMA inhibition on chemotherapy efficacy, and whether oocyte quality and offspring health are preserved long-term.
To test if blocking PUMA-mediated apoptosis affects tumour cell survival, human breast cancer cells (MDA-MB-231) were incubated with PUMA inhibitor (PUMAi; 0-250µM) ± an IC50 concentration of cyclophosphamide derivative 4-HC (5µM). After 48h, 4-HC alone reduced viability to 54% (p<0.0001) and co-treatment with PUMAi did not increase cell survival, with viability remaining at ~50% across all concentrations. Similarly, patient-derived breast cancer organoids (HBC14) were exposed to PUMAi (0-100µM) ± 4-HC (5µM) on days 1, 3 and 5. After 48h, no changes in viability were observed after PUMAi co-treatment, confirming that PUMA inhibition does not compromise chemotherapy efficacy in vitro.
To evaluate fertility and offspring health, mice (n=10/group) received 150mg/kg cyclophosphamide ± 10mg/kg PUMAi, and were bred for three litters. While average litter sizes were similar, cyclophosphamide alone dramatically impacted offspring health, with only 28% of pups surviving past PN5 versus 69% from control-treated dams (p<0.001). Strikingly, PUMAi improved survival to 54% (p<0.05), indicating oocyte quality and offspring health are effectively preserved.
Together, these data demonstrate that PUMA inhibition is a promising avenue for oncological fertility preservation, strongly warranting further investigation with other chemotherapeutic agents.