Sanofi SA / Skyhawk Therapeutics Inc.

Oncology and Immunology (RNA-Splicing Modulation)

2147.5M US cases/yr · $45.0B Global autoimmune + targeted oncology small-molecule market 2023 · ~30% Share of human genes affected by alternative splicing disease biology

Disease Overview

The Sanofi-Skyhawk collaboration targets previously undruggable oncology and immunology proteins via RNA splicing modulation — a small-molecule mechanism pioneered commercially by Spinraza (nusinersen, Biogen) in SMA and validated systemically by Risdiplam (Evrysdi, Roche). In oncology, splicing-modulator candidates target exon inclusion/exclusion in transcripts that regulate tumor suppressor function, MYC-driven transcription, and splicing-factor-mutant cancers (SF3B1-mutant MDS/CLL affects ~4,000-7,000 U.S. annual cases). Immunology applications include autoimmune disease where splicing dysregulation drives pathogenic isoform expression, with addressable populations spanning lupus (~200,000 U.S. prevalent), IBD (~3M U.S. prevalent), and MS (~1M U.S. prevalent). Sanofi has publicly articulated specialty care as a growth priority post-Dupixent (>$11B 2023 sales) and views novel modalities against historically intractable intracellular targets as a strategic pipeline gap. Skyhawk's SkySTAR platform is one of only a handful of dedicated RNA-splicing drug-discovery engines with demonstrated small-molecule tractability against targets outside the SMN-splicing paradigm. Pricing for approved splicing modulators has clustered in the $300K-700K annual range for orphan indications, suggesting meaningful revenue per asset if any program reaches commercial approval in rare oncology or immunology populations.

Competitive Landscape

The RNA splicing modulator competitive landscape is thin but deepening. Approved precedents are Spinraza (nusinersen, Biogen/Ionis) antisense oligonucleotide for SMA, Evrysdi (risdiplam, Roche/PTC) the first oral small-molecule splicing modulator, and H3B-8800 (formerly Eisai, discontinued) which established MBNL/SF3B1 proof-of-concept in MDS. Clinical-stage small-molecule competitors to Skyhawk include Remix Therapeutics (REMIX platform, partnered with Johnson & Johnson and Roche), Expansion Therapeutics (FAST platform, Novartis and Lilly partnerships), and PTC Therapeutics' extended splicing pipeline beyond Evrysdi. Oncology-focused splicing players include Nurix Therapeutics (ligand-mediated degraders overlapping splicing targets) and specific SF3B1 modulator programs at Broad spinouts. Sanofi's positioning leverages the collaboration to access splicing-modulator optionality across its core specialty care franchise (multiple myeloma via Sarclisa, immunology via Dupixent/Kevzara), while Skyhawk retains platform independence for non-oncology/immunology indications.