Mersana Therapeutics (MRSN) Leerink Global Healthcare Conference 2025 summary

Company overview and platform innovation

• Focuses on antibody-drug conjugates (ADCs) for oncology, aiming to address limitations of existing MMAE and topo-based platforms.

• Developed a proprietary auristatin payload to avoid neutropenia, neuropathy, ocular toxicity, myelosuppression, and ILD.

• Platform enables targeting both established and novel antigens with improved safety and efficacy.

Lead program (MME/B7-H4 ADC) clinical progress

• MME is the lead clinical asset, using the Dolasynthen platform, with ongoing expansion in triple negative breast cancer (TNBC) and post-topo patients.

• Fast track designation received for breast cancer post-topo, addressing a growing patient population with limited options.

• Demonstrated a differentiated safety profile, with reversible grade 3 AST increases and manageable proteinuria.

• Achieved a 23% confirmed response rate in heavily pretreated, B7-H4-positive patients, including TNBC post-topo.

Safety and mitigation strategies

• Proteinuria observed at higher doses is reversible and not associated with renal failure; managed by protocol amendments and prophylactic ACE/ARB use.

• Treatment interruptions due to proteinuria are being addressed to enable higher dosing and potentially improved efficacy.

• Collaboration with onco-nephrologists led to better understanding and management of podocytopathy.