Boundless Bio与Serapha达成全股权合并交易

SAN DIEGO and NEW YORK, June 23, 2026 (GLOBE NEWSWIRE) -- Boundless Bio, Inc. (Nasdaq: BOLD) and Serapha Bio, Inc., a privately held biotechnology company developing an investigational in vivo base editing therapy for Alpha-1 Antitrypsin Deficiency (AATD), today announced that they have entered into a definitive merger agreement pursuant to which Serapha will combine with Boundless Bio in an all-stock merger. Prior to the closing, Boundless Bio expects to declare a cash dividend to pre-merger Boundless stockholders. Upon completion of the transaction, the combined company plans to operate under the name Serapha Bio, Inc. and is expected to trade on Nasdaq under the ticker symbol “AATD”.

In support of the proposed merger, Serapha has secured commitments for pre-closing private investments of approximately $230 million from a syndicate of investors co-led by RA Capital Management and RTW Investments and includes participation by Janus Henderson Investors, Decheng Capital, Vivo Capital, Casdin Capital, LifeSci Venture Partners, Logos Capital, Balyasny Asset Management, and Eventide Asset Management, of which approximately $138 million has already been funded in a Series A financing. The additional $92 million in funding is expected to close substantially concurrently with the merger, subject to customary closing conditions.

The combined company’s cash and cash equivalents balance at closing, including the funds from the private placement, is expected to fund Serapha’s operations into the second half of 2029 and provide runway through Phase 2 completion and Phase 3 initiation for SERP-01.

“This transaction provides Serapha with the public-market platform and capital to advance SERP-01 through a U.S. clinical program with conviction,” said Roderick Wong, MD, Managing Partner and Chief Investment Officer at RTW Investments. “The early clinical data generated with SERP-01 give us confidence that this is a potentially best-in-class base editing therapy that can restore AAT to physiologic levels in patients with the most severe form of this disease.”

Serapha licensed SERP-01, developed as YOLT-202 in Greater China, from YolTech Therapeutics in June 2026, in exchange for an upfront cash payment and a minority equity stake in Serapha. YolTech is also eligible to receive regulatory and commercial milestones totaling over $2 billion and tiered royalties on net sales of SERP-01. YolTech has been enrolling AATD patients in an Investigator-Initiated Trial (IIT) in Renji Hospital, Shanghai, China and retains development and commercialization rights for the Greater China territory.

“SERP-01 has a highly differentiated clinical profile, and, with this financing and merger agreement, Serapha is well positioned to deliver meaningful benefit for the up to 100,000 Americans – and many more around the world – who suffer from the life-threatening effects of severe AATD,” said Rajeev Shah, Managing Partner at RA Capital. “Serapha will hit the ground running with company building support from RTW Investments and RA Capital, including RA Capital’s Blackbird clinical development accelerator.”

“Since our founding, Boundless has pioneered a novel approach rooted in extrachromosomal DNA (ecDNA) biology to attempt to treat some of the most aggressive and difficult cancers. While we’ve deepened our understanding of ecDNA’s foundational role in certain cancers, the early clinical data for BBI-940 did not support continuing to advance this program,” said Zachary Hornby, President and Chief Executive Officer of Boundless Bio. “I am incredibly proud of our Boundless Bio team and their rigorous advancement of our novel science over the past seven years. We believe this transaction represents a strong opportunity to deliver meaningful value for our stakeholders, while providing Serapha with a public-market platform to advance novel therapies for people with rare diseases.”

The combined company will focus on the development and commercialization of Serapha’s lead clinical-stage candidate, SERP-01, for the treatment of severe AATD. AATD is a hereditary disorder most commonly caused by the SERPINA1 E342K point mutation, which causes the liver to produce a misfolded form of AAT, known as Z-AAT, in place of the normal M-AAT. The resulting toxic accumulation of Z-AAT polymers in the liver can lead to hepatitis, fibrosis, and cirrhosis, while reduced levels of functional AAT in circulation leave the lungs vulnerable to progressive emphysema and COPD. There is estimated to be up to 100,000 individuals with the severe PiZZ genotype in the United States, and current treatment is limited to supportive care, liver transplantation for end-stage disease, and weekly intravenous augmentation therapy that does not address the underlying liver pathology.

SERP-01 is an investigational in vivo base editing therapy designed to correct the SERPINA1 E342K mutation at its source. By restoring production of functional M-AAT while reducing toxic Z-AAT, SERP-01 has the potential to address both the liver and lung manifestations of the disease with a single administration.

The Proposed Transaction

Under the terms of the merger agreement, as of the closing and subject to the assumptions and adjustments set forth in the merger agreement, the pre-merger Boundless Bio stockholders are expected to own approximately 3.7% of the combined company and the pre-merger Serapha stockholders (inclusive of those investors participating in the pre-closing financings) are expected to own approximately 96.3% of the combined company. Prior to closing, Boundless Bio expects to declare a cash dividend to pre-merger Boundless Bio stockholders to distribute excess net cash, which is currently expected to be approximately $44 to $48 million, subject to adjustment based on Boundless Bio’s net cash at closing and the terms of the merger agreement.

The transaction has received unanimous approval by the Board of Directors of both companies and is expected to close in the fourth quarter of 2026, subject to certain closing conditions, including, among others, approval by the stockholders of each company, approval of the Nasdaq listing application, the effectiveness of a registration statement to be filed with the U.S. Securities and Exchange Commission (SEC) to register the securities to be issued in connection with the proposed merger, expiration, or termination of the waiting period under the Hart-Scott-Rodino Antitrust Improvements Act of 1976, as amended, if applicable, and the satisfaction of other customary closing conditions.

Lucid Capital Markets is serving as exclusive financial advisor and Latham & Watkins LLP is serving as legal counsel to Boundless Bio. Wedbush Securities Inc. is serving as exclusive financial advisor and Gibson, Dunn & Crutcher LLP and Goodwin Procter LLP are serving as legal counsel to Serapha.

Conference Call Information
Boundless Bio and Serapha Bio will host a joint conference call and webcast on June 23, 2026 at 8:30 a.m. ET. Please access the presentation by clicking on the following link: https://edge.media-server.com/mmc/p/w8sgnrsw