Boundless Bio agrees to reverse merger with Serapha Bio in $230M gene‑editing deal

Biotech oncology spinout Boundless Bio (Nasdaq:
BOLD) has agreed to merge with private biotech Serapha Bio in an all‑stock reverse merger, making Serapha the controlling owner of the combined company.

Serapha Bio is a clinical‑stage gene‑editing company developing SERP‑01, an in vivo base‑editing therapy for Alpha‑1 Antitrypsin Deficiency (AATD).

Under the terms, pre‑merger Serapha equityholders will own about 96.3% of the combined company, while existing Boundless Bio equityholders will own about 3.7% and receive a pre‑closing cash dividend of roughly $44–$48 million.

The combined company will be named Serapha Bio and is expected to trade on Nasdaq under the ticker AATD, with the deal slated to close in Q4 2026, pending stockholder and regulatory approvals.

Concurrent financing of about $230 million (including Serapha’s Series A and a PIPE) is expected to fund SERP‑01 into the second half of 2029, while Boundless’s oncology asset BBI‑940 will be wound down after early clinical data showed lower‑than‑expected human exposure.