June 23026 —
Serapha Bio has launched with $230 million in funding commitments to advance SERP-01, an investigational in vivo base editing therapy for alpha-1 antitrypsin deficiency, or AATD. The company is being formed through a reverse merger with Boundless Bio and will trade under the ticker AATD after the transaction closes.
The financing is led by RA Capital Management and RTW Investments, with participation from Janus Henderson Investors, Decheng Capital, Vivo Capital, Casdin Capital, LifeSci Venture Partners, Logos Capital, Balyasny Asset Management, and Eventide Asset Management. The funding includes a $138 million Series A financing and an additional $92 million expected to close upon completion of the merger.
SERP-01 was originally developed by YolTech Therapeutics in China and licensed to Serapha. Under the agreement, YolTech receives an upfront payment and a minority equity stake in Serapha, retains rights to SERP-01 in China, and is eligible for more than $2 billion in potential milestone payments tied to the program’s development and commercial success.
AATD is a hereditary disorder in which patients cannot produce sufficient levels of functional alpha-1 antitrypsin, or AAT, a liver-produced protein that helps protect the lungs from inflammation and tissue damage. The most common severe form of the disease is linked to the SERPINA1 E342K, or PiZZ, mutation, which causes production of misfolded Z-AAT protein. This can lead to both lung disease from AAT deficiency and liver disease from accumulation of abnormal protein.
SERP-01 is designed to correct the disease-causing SERPINA1 E342K mutation through in vivo base editing, potentially restoring production of functional AAT at physiologic levels. The therapy is being investigated as a treatment for patients with the severe PiZZ genotype, a group estimated to include up to 100,000 people in the United States.
YolTech has been enrolling patients in an investigator-initiated study of SERP-01 in Shanghai. According to Serapha, early clinical data support confidence in the therapy’s potential to restore AAT levels in patients with severe AATD. The company expects the new funding to support operations into the second half of 2029, enabling completion of Phase 2 testing and initiation of Phase 3 development.
The launch also reflects growing interest in cross-border biotech asset formation, particularly around genetic medicines developed in China and licensed into newly capitalized companies for global development. In this case, Serapha combines a China-originated in vivo base editing program with substantial U.S.-led financing and a public-market path through the Boundless Bio reverse merger.
AATD is becoming an increasingly active area for therapeutic development after decades with limited innovation. Other companies are pursuing recombinant protein, RNA editing, and gene editing approaches aimed at restoring functional AAT or reducing disease-causing Z-AAT. Serapha’s entry adds another genetic medicine strategy to the field, with a focus on permanent correction of the underlying PiZZ mutation.
If successful, SERP-01 could represent a disease-modifying approach for AATD by addressing the genetic root cause rather than relying on chronic protein augmentation. The next key milestones will include further clinical data from ongoing studies, Phase 2 execution, and preparation for potential Phase 3 development.
