Welcome to the Weekly Rundown where the DDN editors cover this week’s top biotech and pharma news.
Tenaya Therapeutics’ gene therapy for heart condition placed on hold
The FDA placed a clinical hold on Tenaya Therapeutics’ Phase 1b/2a trial for their gene therapy, MyPEAKTM-1, to treat hypertrophic cardiomyopathy caused by mutations in the MYBPC3 (myosin-binding protein C3, cardiac-type) gene. The condition is associated with a thickened heart muscle that increases the risk of heart failure or even sudden death. According to a statement, the FDA requested an amendment “to the protocol primarily to standardize activities related to patient monitoring and management of the immunosuppression regimen across trial sites.” For their part, Tenaya stated that the therapy has been “generally well tolerated and since the DSMB review, there have been no new meaningful safety events.” They also noted that they are collaborating with the FDA to quickly resolve the hold, and they do not anticipate any delays in milestones or development timelines. – Allison Whitten
Experimental CRISPR treatment lowers cholesterol by half in first human study
In a potential breakthrough for heart disease prevention, scientists at the Cleveland Clinic have shown that a single infusion of a CRISPR-based gene-editing therapy can sharply cut cholesterol and triglyceride levels — possibly for life. The early Phase 1 trial, led by Luke Laffin and Steven Nissen, tested the treatment in 15 patients with high cholesterol or triglycerides that persisted despite standard medications such as statins. The therapy, developed by CRISPR Therapeutics, uses CRISPR to disable the ANGPTL3 (Angiopoietin-like protein 3) gene, which normally slows the breakdown of fats in the blood by inhibiting lipoprotein and endothelial lipases. Participants receiving the highest doses saw LDL cholesterol drop by 50 percent and triglycerides by 55 percent after six months. While the small study was designed mainly to test safety, no serious side effects were reported, and results, published in The New England Journal of Medicine, suggest durable lipid control could be possible with a one-time treatment. If confirmed in larger trials, the approach could revolutionize heart disease prevention, offering a permanent alternative to daily statins or repeat injections. – Bree Foster
UK launches £60 million strategy to accelerate the end of animal testing
Animal testing in scientific research is set to be phased out more quickly under a new government strategy unveiled by Science Minister Lord Vallance. The £60 million roadmap outlines how the UK will accelerate the shift toward advanced non-animal methods such as organ-on-a-chip systems, AI-driven molecular analysis, and 3D bioprinted tissues. The plan aims to end certain regulatory tests on animals by 2026, and significantly reduce studies involving dogs and primates by 2030. Backed by new funding from the Medical Research Council, Innovate UK, and the Wellcome Trust, the initiative will establish a national hub to fast track validation and regulatory approval for alternatives, while supporting early-career training and cross-sector collaboration. “This strategy is an important step forward for animal welfare in our country. By harnessing our scientific excellence, we can deliver real benefits for animal welfare while advancing innovative research that improves lives,” said Animal Welfare Minister Baroness Hayman in the press release. – Bree Foster
FDA launches new ‘plausible mechanism pathway’ to fast-track bespoke therapies
The FDA has introduced a new regulatory framework called the “plausible mechanism pathway”, aimed at speeding the development and approval of individualized treatments for rare and ultra-rare diseases that cannot feasibly be studied in traditional clinical trials. Announced in the New England Journal of Medicine by FDA Commissioner Martin Makary and Deputy Commissioner Vinay Prasad, the pathway offers a streamlined process for therapies that target a clearly defined biological cause of disease and demonstrate early signs of efficacy and safety. The agency plans to issue joint guidance through the Center for Drug Evaluation and Research (CDER) and Center for Biologics Evaluation and Research (CBER) to outline standards for participation. Inspired in part by rapid-response cases like that of KJ Muldoon — a baby successfully treated with a CRISPR-based therapy within seven months of diagnosis — the framework establishes clear criteria for validation and follow-up, requiring data that confirm the therapy engages its target and benefits the patient without major harm. Initially focused on life-threatening or severely disabling rare conditions, the pathway could eventually extend to other diseases lacking proven treatments, potentially reshaping how bespoke genetic, cellular, and even small-molecule therapies reach patients. – Andrea Corona
Day One Biopharmaceuticals to acquire Mersana Therapeutics in deal worth up to $285 million
Day One Biopharmaceuticals has announced plans to acquire Mersana Therapeutics in a transaction valued at up to $285 million, combining cash and contingent milestone payments tied to the progress of Mersana’s antibody-drug conjugate (ADC) programs. Central to the acquisition is Emi-Le (emiltatug ledadotin; XMT-1660), Mersana’s B7-H4–targeting ADC designed to treat solid tumors such as triple-negative breast cancer using the company’s Dolasynthen platform. The deal, unanimously approved by Mersana’s board, represents an equity value of about $129 million at closing and is expected to be finalized by the end of January 2026, pending customary approvals. Once completed, Mersana will become a wholly owned subsidiary of Day One, and its stock will be delisted. Mersana CEO Marty Huber said the acquisition highlights the promise of Emi-Le and the opportunity to accelerate its development for cancers with limited treatment options, including adenoid cystic carcinoma. – Andrea Corona
Roche’s BTK inhibitor for MS shows promise in late stage trials
On Monday, Genentech, a Roche company, announced that its Bruton’s tyrosine kinase (BTK) inhibitor, fenebrutinib, led to significant reductions in relapses in relapsing multiple sclerosis (RMS) patients in a Phase 3 trial compared to teriflunomide, an FDA-approved immunomodulatory agent for RMS. They also shared data showing that fenebrutinib was at least as effective in delaying disability progression as Ocrevus, a monoclonal antibody approved as the only current therapy for primary progressive MS (PPMS). “These unprecedented results suggest that fenebrutinib could potentially become a best-in-disease medicine as the first high-efficacy, oral treatment for people with RMS or PPMS,” said Levi Garraway, Genentech’s Chief Medical Officer and Head of Global Product Development, in the press release. The promising results come after Merck and Biogen abandoned BTK inhibitors in the MS space over the last few years, while Novartis is still moving their own BTK inhibitor through the pipeline, and Sanofi’s tolebrutinib is under FDA review to treat non-relapsing, secondary progressive MS — despite a recent delay in their decision. – Allison Whitten
