Spruce readies December filing for MPS IIIB enzyme therapy as it reworks financing

Spruce Biosciences used its third-quarter 2026 results, published on 9 November, to reaffirm that it will file a Biologics License Application for tralesinidase alfa (TA-ERT) in December. The submission will ask the US Food and Drug Administration for conditional clearance in mucopolysaccharidosis type IIIB (MPS IIIB). The company's case will rely on a laboratory marker, heparan sulfate nonreducing end measured in cerebrospinal fluid (CSF HS-NRE), rather than a clinical outcome. The information available does not include revenue, pricing or peak-sales figures for the product.

Alongside the regulatory timetable, the company has tidied up its balance sheet. On 6 November it amended its loan agreement with Avenue, lifting the sum available under the facility's second tranche to $15 million and lengthening the period in which it pays interest only. The information available does not give the new end date for that period, or any other changed terms.

Spruce has also placed its CRHX-101 antibody programme in a separate subsidiary, Adrenyx Biosciences. The new company has drawn $5 million from a convertible note facility that can reach $10 million. The information available does not say who provided the notes or on what conversion terms.

On the clinical side, Spruce started a US expanded access programme this month. It plans to open the TrAnsform confirmatory study in December, a trial the FDA asked for. As general context, the FDA's accelerated pathway lets drugs for serious conditions reach the market on a surrogate endpoint judged reasonably likely to predict benefit, with confirmatory evidence required afterwards.