Ultragenyx Pharmaceutical today proposed to acquire Dimension Therapeutics for approximately $138 million—nearly two thirds above the price offered by Regenxbio last month—setting up a potential bidding war for the gene therapy developer.

At $5.50 per share cash, Ultragenyx’ offer is 61% higher than Regenxbio’s $3.41-per-share all-stock deal for Dimension, valued at about $85 million and announced on August 25.

“We share Dimension's vision for bringing transformational new therapies to patients with rare genetic diseases and believe that bringing our two companies together would accelerate the process of bringing important new therapies to market for patients,” Ultragenyx CEO and president Emil D. Kakkis, M.D., Ph.D., said in a statement.

Dr. Kakkis is also a scientific advisor to Dimension.

“This transaction provides a compelling opportunity to create value by leveraging Ultragenyx's advanced clinical and regulatory expertise as well as its rare metabolic disease commercial infrastructure to advance Dimension's rare disease–focused gene therapies and bring much needed new treatments to market,” Dr. Kakkis added.

Regenxbio had not commented on Ultragenyx’ offer at deadline.

Ultragenyx said its offer represented a premium of more than 358% to Dimension's share price as of August 24, the day before the company joined Regenxbio in announcing their deal—as well as premiums of 24% and 48% over the implied value of Regenxbio’s offer based on Regenxbio’s last closing price and trailing 20-trading-day, volume-weighted average price as of September 15.

“Our all-cash offer provides meaningfully greater value and certainty to Dimension shareholders compared to the proposed all-stock acquisition by Regenxbio,” Dr. Kakkis added. “We believe Ultragenyx and its product candidates are highly complementary to Dimension's and present no competitive overlap, giving us confidence that we could combine our two companies quickly and seamlessly.”

Ultragenyx added that it anticipated that it could satisfy customary closing conditions and complete its tender “as soon as 25 business days after merger agreement signing.”

Rare Disease, Hemophilia Candidates

The company that completes a deal will add to its pipeline Dimension’s DTX301 and DTX401 candidates—as well as Dimension’s DTX201, a gene therapy candidate for hemophilia A

DTX301 is a gene therapy candidate for ornithine transcarbamylase (OTC) deficiency that uses Regenxbio’s novel adeno-associated virus (AAV) NAV® AAV8 vector to deliver a copy of the OTC gene to liver cells. DTX401 is a gene therapy candidate for glycogen storage disease type Ia (GSDIa), in which an NAV AAV8 vector is used for delivering a copy of the glucose-6-phosphatase (G6Pase) gene to liver cells. Both have been designated as orphan drugs in the U.S. and Europe—and both have been developed under exclusive licenses previously granted to Dimension by Regenxbio.

DTX201 is being developed and commercialized through an up-to-$252 million collaboration with Bayer launched in 2014.

Earlier this year, Dimension halted development of DTX101, a AAVrh10-based gene therapy candidate for moderate/severe-to-severe hemophilia B, after disappointing Phase I/II data convinced the company that it would not meet the minimum target product profile for continued development or future commercialization.

NAV includes novel AAV vectors, such as rAAV7, rAAV8, rAAV9, and rAAVrh10. NAV technology was discovered in the lab of Regenx’ scientific founder James M. Wilson, M.D., Ph.D., director of the gene therapy program at the University of Pennsylvania. Dr. Wilson also chairs Dimension’s Scientific Advisory Council, and serves as clinical development editor of Human Gene Therapy, a journal published by GEN publisher Mary Ann Liebert Inc.

Dr. Wilson and Human Gene Therapy Editor-in-Chief Terence R. Flotte, M.D., are among members of Dimension’s Scientific Advisory Council.

Previous articleFat-Modifying Enzyme May Be Key to Cancer and Metabolic Diseases
Next articleCRISPR Identifies Rare Type of Glycosylation Critical for Cancer