Cytotoxic activity and cell specificity of a novel LHRH peptide drug conjugate, D‐Cys6‐LHRH vedotin, against ovarian cancer cell lines

Abstract Ovarian cancer is the most deadly female gynaecological malignancy in developed countries and new treatments are urgently needed. The luteinising hormone releasing hormone (LHRH) peptide drug conjugate Zoptarelin doxorubicin is one such potential new drug modality that entered clinical trials for treating LHRH receptor‐positive gynaecological cancers. However, development stopped after disappointing Phase 3 results in 2017. We believe the lack of efficacy was due to linker instability and payload potency. In this work, we replaced its linker‐toxin with vedotin (MC‐VC‐PABC‐MMAE), yielding the novel peptide drug conjugate D ‐Cys6‐LHRH vedotin. A GI 50 and cell specificity comparison against cancerous and non‐cancerous ovarian cell lines showed significantly superior bioactivity and selectivity over Zoptarelin doxorubicin (GI 50 4 vs. 453 nM) and other chemotherapeutic drugs used for treating ovarian cancers. Our results suggest D ‐Cys6‐LHRH vedotin can potentially be used as a treatment for ovarian cancer.