UPDATE: Lilly, Astellas circle Sangamo assets as biotech files for bankruptcy

Sangamo Files for Bankruptcy, Sells Key Assets to Lilly and Astellas

Sangamo Therapeutics has filed for voluntary Chapter 11 bankruptcy, initiating a court-supervised reorganization and asset sale. The biotech is laying off 51 employees, representing 40% of its workforce, while retaining 77 staff to continue work on programs central to bids from Eli Lilly and Astellas. Lilly is eyeing Sangamo’s capsid delivery, zinc finger, and modular integrase platforms, along with the ST-506 prion disease program. Astellas is bidding for isaralgagene civaparvovec (ST-920), a pivotal-stage gene therapy for Fabry disease, for which Sangamo began a rolling BLA submission in December 2025. Both companies are serving as "stalking horse bidders." Another asset, giroctocogene fitelparvovec for hemophilia A, is also expected to be sold after Pfizer terminated its licensing deal.

• Sangamo Therapeutics has initiated voluntary Chapter 11 bankruptcy proceedings to facilitate a court-supervised reorganization and asset sale. This strategic move includes a significant workforce reduction of 51 employees, approximately 40% of its team. However, 77 staffers will be retained to ensure continuity for key programs that are central to the acquisition bids from Eli Lilly and Astellas, aiming to maximize value through the bankruptcy process.
• Eli Lilly is positioned to acquire several of Sangamo's advanced technology platforms, specifically its capsid delivery, zinc finger, and modular integrase platforms. Additionally, Lilly is bidding for the ST-506 prion disease program, an AAV-based gene therapy designed using Sangamo's STAC-BBB technology. This builds upon a prior collaboration where Lilly paid $18 million upfront for STAC-BBB, with potential milestones up to $1.4 billion, highlighting Lilly's continued interest in Sangamo's gene therapy capabilities.
• Astellas has made a stalking horse bid for isaralgagene civaparvovec (ST-920), Sangamo's most advanced asset. This pivotal-stage gene therapy targets Fabry disease, a rare genetic disorder. Positive Phase 1/2 data previously demonstrated improved kidney function at 52 weeks for patients. Sangamo commenced a rolling Biologics License Application (BLA) submission for ST-920 with the FDA in December 2025, continuing data submission in March 2026, and is seeking accelerated approval.
• Beyond the Lilly and Astellas deals, Sangamo plans to sell giroctocogene fitelparvovec, a late-stage gene therapy for hemophilia A. This candidate previously had Pfizer's support, but the licensing agreement was terminated in late 2024, impacting Sangamo's financial stability. The current bankruptcy filing and asset sales are a direct result of Sangamo's comprehensive review of strategic alternatives, aiming to provide a clear framework for value-maximizing transactions amidst its financial challenges.

Addressing Unmet Needs in Fabry Disease Treatment

Current therapeutic options for Fabry disease — principally enzyme replacement therapy (ERT) and the pharmacological chaperone migalastat — have meaningfully advanced patient management, yet neither approach fully corrects the underlying enzymatic deficiency or reliably halts disease progression. Significant gaps persist across efficacy, patient eligibility, biomarker reliability, and mechanistic understanding, collectively limiting the ceiling of therapeutic benefit achievable with existing modalities.

• ERT fails to prevent long-term organ complications in most patients. Despite demonstrated benefits on cardiac, renal, and neurological endpoints, long-term ERT treatment does not fully revert Fabry disease pathology, and cardiac, renal, and cerebrovascular complications continue to develop in the majority of patients over time.

• Clinical response to ERT is highly dependent on timing of initiation. Patients with advanced end-organ damage respond suboptimally to ERT compared with those who initiate therapy prior to the development of irreversible organ fibrosis, underscoring the critical importance of early diagnosis and treatment.

• Key unresolved questions surround ERT optimization. Outstanding issues include the optimal dosing regimen, the ideal therapeutic window for treatment initiation, and the clinical impact of anti-drug antibodies — all of which remain inadequately defined.

• ERT imposes a substantial practical and financial burden. Lifelong intravenous infusion schedules are burdensome for patients, and the cost-effectiveness of ERT is increasingly being questioned in the literature.

• Migalastat is restricted to patients with amenable mutations, and real-world amenability data are inconsistent. The chaperone is only applicable to a subset of patients harboring specific genetic variants, and emerging real-world evidence has raised concerns that in vitro amenability designations do not always translate to in vivo clinical response — contrasting with results from pivotal clinical trials. Additionally, the neurological effects of migalastat have not been formally studied.

• Pharmacodynamic biomarkers lack sufficient reliability. The utility of α-galactosidase A activity and globotriaosylsphingosine (lyso-Gb3) as response biomarkers remains unclear, complicating therapeutic monitoring and endpoint selection in both clinical practice and trial design.

• Tissue biodistribution of ERT is suboptimal. Preclinical data indicate that agalsidase beta is predominantly sequestered in the liver and spleen — organs not primarily affected in Fabry disease — raising concerns about target tissue delivery, and extrapolation of murine pharmacokinetic data to humans has proven unsuccessful.

• The pathophysiological mechanisms driving organ damage remain poorly understood. The ambiguity surrounding Fabry disease-mediated end-organ injury directly hinders the rational development of next-generation therapeutic strategies aimed at disease modification beyond enzymatic replacement.

Pioneering Gene Editing Assets Find New Homes Amidst Biotech Reorganization

The news of Sangamo Therapeutics filing for Chapter 11 bankruptcy and initiating an asset sale marks a poignant moment for the field of gene editing. As a pioneer in developing therapies based on zinc finger DNA-binding protein (ZFP) technology, Sangamo has been at the forefront of exploring potentially curative treatments for a range of genetic and infectious diseases, including lysosomal storage disorders and HIV. This reorganization underscores the immense capital requirements and inherent risks associated with bringing groundbreaking genomic medicines from concept to commercialization.

However, this event is not merely a story of a biotech's struggle; it's also a testament to the enduring value of its scientific contributions. The strategic interest from pharmaceutical giants like Eli Lilly and Astellas highlights the continued belief in the potential of gene editing. Lilly's pursuit of Sangamo's foundational platforms—including capsid delivery, zinc finger, and modular integrase technologies—suggests a long-term vision to integrate these core capabilities into its broader drug discovery and development efforts. This move could significantly bolster Lilly's footprint in genomic medicine, providing versatile tools for future therapeutic innovation.

Similarly, Astellas' bid for isaralgagene civaparvovec (ST-920), a pivotal-stage gene therapy for Fabry disease, represents a more immediate strategic play. Acquiring a late-stage asset in a rare disease indication offers a potential fast track to market entry and strengthens Astellas' rare disease portfolio. This type of acquisition reflects a broader trend where larger companies are seeking to de-risk their pipelines by acquiring advanced programs from smaller biotechs that have navigated early-stage development.

Despite these strategic opportunities, inherent risks remain. The zinc finger nuclease (ZFN) technology, while innovative, operates within a competitive and rapidly evolving gene editing landscape. Furthermore, even pivotal-stage gene therapies like ST-920 carry clinical and regulatory uncertainties, as evidenced by the complexities seen in other gene therapy programs. The challenges faced by Sangamo, including prior partnership terminations, serve as a reminder of the significant hurdles in developing and commercializing these complex, high-cost therapies. Ultimately, this reorganization signifies a critical juncture, where pioneering gene editing assets are finding new homes, potentially accelerating their path to patients under the stewardship of larger, more resourced pharmaceutical companies.