391: Breaching the IBD efficacy ceiling, and sham surgeries

What It Covers

The Readout Loud covers two major biotech stories: UniCure's regulatory standoff with the FDA over sham surgery requirements for its Huntington's disease gene therapy, and Spire Therapeutics CEO Cameron Turtle explaining how combination biologics aim to break IBD's 30% remission ceiling.

Key Questions Answered

• •IBD Efficacy Ceiling: Every approved IBD drug class — including biologics like Entyvio and Skyrizi — achieves clinical remission in only roughly 25–30% of patients. Combination therapies targeting multiple disease pathways simultaneously show additive efficacy without apparent additive safety risks, making them the most viable strategy to push remission rates meaningfully above that ceiling.
• •Combination Therapy Benchmarking: Johnson & Johnson's VEGA trial established the first randomized proof that combining two biologics yields additive IBD remission rates, reaching just under 50%. Spire's hypothesis is that replacing weaker components — specifically TNF inhibitors — with superior mechanisms like alpha-4-beta-7 or TL1A could add 10 or more percentage points on top of that benchmark.
• •TL1A as a Pipeline-in-a-Product Target: TL1A inhibitors are being evaluated across up to seven distinct indications in 2025, including rheumatoid arthritis, psoriatic arthritis, axial spondyloarthritis, atopic dermatitis, and MASH. This broad applicability — comparable to Humira's multi-indication profile — explains why Blackstone committed $400 million to back a single TL1A program developed by Teva and Sanofi.
• •Combination Pricing Strategy: Payers currently reject off-label dual-biologic combinations because they require covering two branded drugs at double the cost with no combined clinical data. Spire's approach — co-formulating two antibodies into one branded product dosed four times annually — is designed to be priced comparably to a single biologic, making payer approval and cost-effectiveness arguments substantially more straightforward.
• •FDA Regulatory Whipsaw in Rare Disease: The shift from Peter Marks to Vinay Prasad at FDA's cell and gene therapy division represents a move from permissive, flexible approval standards to a significantly higher evidentiary bar. Rare disease developers should anticipate stricter controlled trial requirements — including controversial sham surgery controls — rather than relying on historical comparator data for approval.