The role of liquid biopsy in the management of concurrent Hodgkin lymphoma and ovarian carcinoma treated with nivolumab

The simultaneous occurrence of Hodgkin lymphoma (HL) and ovarian carcinoma (OC) is rare and presents unique challenges in diagnosis and treatment. Circulating tumour DNA (ctDNA) offers a minimally invasive method for detecting minimal residual disease in both malignancies. We present the case of a 42-year-old woman with relapsed HL and advanced high-grade serous OC, treated with nivolumab, a PD-L1 inhibitor. After surgery and chemotherapy for OC, she received salvage therapy for cHL, including autologous stem cell transplantation. During the therapy, the patient was monitored using PET/CT and ctDNA analysis. CtDNA analysis detected a Hodgkin-driven compound mutation in the STAT6 gene (N417Y/N421S) allowing early relapse detection and treatment adjustments, detected progression of the disease led to nivolumab initiation. The mutation was used to monitor minimal residual disease (MRD). For ovarian carcinoma, presence of the BRAF V600E mutation as the marker was detected from archival paraffin-embedded ovarian tissue collected at the time of diagnosis, during ctDNA monitoring, BRAF V600E associated with OC remained undetectable, aligning with remission. This case highlights the potential of ctDNA to improve monitoring of concurrent malignancies, especially during immunotherapy, where PET/CT may lead to false-positive results. It is the first reported case of nivolumab treatment for chemo-refractory relapsed HL and OC, demonstrating the utility of ctDNA in managing dual malignancies.