Survivin-Targeting Antisense Oligonucleotides in Cancer Therapy.

Survivin (BIRC5) is a key inhibitor of apoptosis that is highly overexpressed in many cancers, where it promotes tumour cell survival, mitotic progression, and resistance to therapy. Because survivin is largely absent from normal adult tissues, it represents a selective and promising target for cancer treatment. Antisense oligonucleotides (ASOs) provide a precise approach to silence survivin by targeting its transcripts. Preclinical studies have shown that ASO-mediated reduction of survivin is associated with increased cancer cell death, inhibition of tumour growth, and enhanced sensitivity to other treatments. Early-phase clinical trials of survivin-targeting ASOs have shown evidence of target engagement but ultimately failed to demonstrate consistent clinical benefit and/or encountered dose-limiting toxicities, which hindered their further development. This review outlines survivin's central role in cancer biology, the principles of ASO therapeutics (sequence design, mechanisms of action, chemical modifications, and delivery strategies), and the progress in preclinical and clinical development of survivin-targeting ASOs, while also discussing key challenges that may contribute to their clinical limitations, including inefficient delivery, off-target effects, and systemic toxicities. Collectively, the current status of survivin-targeting ASOs underscores the need for synergistic optimization of delivery platforms and molecular chemistry to improve efficacy and safety, thereby enabling their use in personalised and combination cancer treatment approaches.