Eli Lilly has announced that it will acquire gene therapy developer Adverum Biotechnologies in a deal valued at up to USD 261.7 million, signalling a push into the ophthalmology space.

Under the proposed terms, Lilly will pay USD 3.56 per share in cash, amounting to roughly USD 74.7 million upfront. In addition, shareholders could receive up to USD 8.91 per share in contingent milestone payments, dependent on U.S. regulatory approval of Adverum’s lead candidate, Ixo-vec, within seven years, and achieving more than USD 1 billion in annual global sales within ten years. Should all conditions be met, the total per-share payout would reach USD 12.47.

Adverum’s shares closed at USD 4.18 on Thursday, and rose nearly 3% to USD 4.29 in morning trading the following day.

The deal grants Lilly access to Ixo-vec, a one-time ocular gene therapy currently in late-stage trials for wet age-related macular degeneration (wAMD), a major cause of vision loss in the elderly. The wAMD treatment market in the United States—affecting around 1.5 million patients—is already crowded with frequent-injection therapies such as Roche’s Lucentis and Regeneron’s Eylea.

Several companies are striving to bring a gene therapy alternative to market, including 4D Molecular Therapeutics and the Regenxbio/AbbVie collaboration. Analysts at TD Cowen see strong blockbuster potential, estimating global sales of USD 1.3 billion by 2033, even with modest market penetration.

Earlier this year, Lilly moved in a similar direction by agreeing to acquire gene-editing firm Verve Therapeutics for up to USD 1.3 billion, targeting one-time therapies for cardiovascular disease.

Lilly expects the Adverum transaction to finalise in the fourth quarter.