(Updated Oct. 24,2025 at 12:14 PM)
BOSTON – Eli Lilly and Co. is doubling down on its investment in Boston’s Seaport District, signing a new lease that gives the pharmaceutical giant full control of the building at 645 Summer Street.
According to the Boston Business Journal (BBJ), the Indianapolis-based company (NYSE: LLY) has leased an additional 75,000 square feet in the property — bringing its total space there to 150,000 square feet and making it the sole occupant of the two-story lab facility.
The site, originally built in 1966 and renovated in 2019, was previously home to gene-editing startup Akouos, which Eli Lilly acquired in 2022. Akouos had leased half the building prior to the acquisition. The expanded facility now operates under the name Lilly Harborside Research & Development Labs, BBJ reported.
Strengthening Genetic Medicine Research
The expansion at 645 Summer Street builds on Lilly’s growing footprint in the Seaport, which already includes the Lilly Seaport Innovation Center on Necco Street — a 12-story, 346,000-square-foot hub that opened in 2024. That site serves as the company’s main base for genetic medicine research and houses the East Coast branch of Lilly Gateway Labs, its biotech incubator program.
Allison Howell, Lilly’s associate director of R&D communications, confirmed the new lease to BBJ, saying that “as Lilly’s Seaport presence continues to grow across these two sites, the need to expand at this site grew critical.”
“These research and development facilities are dedicated to advancing Lilly’s efforts in RNA and DNA-based therapies as well as discovering new drug targets to create life-changing medicines across several disease states, including diabetes, obesity, cardiovascular diseases, neurodegeneration, chronic pain, immunology and hearing health,” Howell told BBJ in an email.
A Shift from Cambridge to Boston
As BBJ noted, the opening of Lilly’s Seaport Innovation Center in 2024 marked a significant shift for the company, moving its regional R&D hub from Cambridge — long considered the heart of Greater Boston’s biotech industry — to the city’s waterfront.
With its expanded footprint at 645 Summer Street and the continued growth of its Seaport facilities, Eli Lilly is cementing its presence in one of Boston’s fastest-evolving life sciences clusters.
A Landmark Deal and Modernized Lab Space
“We’re thrilled to be building on our extensive relationship with Eli Lilly through this landmark deal at 645 Summer Street – an expansion that reflects our collective belief in the power of high-quality, purpose-built real estate to empower teams to innovate, scale, and succeed,” said Matthew Polhemus, Vice President, Leasing, at Oxford Properties. “We’ve grown alongside Eli Lilly over the years, supporting their evolving needs and ambitions in Boston’s thriving life sciences ecosystem. This deal, the largest life sciences lease signed in the city’s urban core this year, is a testament to the trust we’ve built with our customers and the shared vision we hold. At Oxford, we remain focused on creating workplace environments where future-thinking companies can succeed.”
Located in Boston’s Seaport neighborhood, 645 Summer Street is a two-story, state-of-the-art lab building designed to support advanced scientific research and development. The building recently underwent a comprehensive modernization, including LEED Gold-targeted upgrades, and offers sweeping views of the historic Reserved Channel, high-performance lab space, and a suite of wellness-focused amenities that cater to today’s research workforce.
