500 Forge, a three-story life science building at Arsenal Yards, refinanced with a Tishman Speyer mezzanine loan
Watertown, MA, August 16, 2025
Tishman Speyer closed a $25.2 million mezzanine loan to refinance 500 Forge at Arsenal Yards, paired with a $94.0 million senior loan from LBBW. The financing, provided to a joint venture led by Boylston Properties with institutional investors advised by J.P. Morgan Asset Management, primarily retired a 2021 construction loan and funded leasing costs tied to a new Mariana Oncology lease. This marks the first investment from Tishman Speyer’s new real estate debt platform. 500 Forge is a three‑story, 162,000 sq ft life science building completed in 2023 and now fully leased to life science tenants.
A joint venture led by Boylston Properties and institutional investors advised by J.P. Morgan Asset Management closed a refinancing package for 500 Forge in Watertown, Massachusetts, anchored by a $25.2 million mezzanine loan provided by Tishman Speyer and a $94.0 million senior loan from Landesbank Baden‑Württemberg (LBBW). The transaction marks the first investment from Tishman Speyer’s newly launched real estate debt platform and was arranged by JLL Capital Markets’ Debt Advisory team.
The financing package was structured to retire a 2021 construction loan for the fully leased asset and to fund leasing costs associated with a newly executed lease by Mariana Oncology, a subsidiary of Novartis. JLL Capital Markets advisers Brett Paulsrud, Henry Schaffer and Geoff Goldstein led the debt advisory work on the refinancing.
The deal is significant for two reasons: it demonstrates early activity from Tishman Speyer’s real estate debt platform, which is targeting institutional‑quality projects across major U.S. cities, and it shows continued investor demand for purpose‑built life science real estate in the Boston suburbs. The new platform will underwrite mezzanine loans, preferred equity, construction financing and loan portfolio acquisitions.
500 Forge sits within the broader Arsenal Yards mixed‑use campus on the edge of West Cambridge and Allston. The three‑story building was completed in 2023, totals roughly 162,000 square feet, and is now fully leased. Current tenants include Mariana Oncology, Orna Therapeutics and AvenCell Therapeutics. The building delivers advanced lab and office space with interior ceiling heights ranging from 15 to 18 feet, outdoor balconies and covered parking.
Proceeds from the mezzanine and senior loans were deployed primarily to retire the original construction financing for the fully leased asset and to cover contractual leasing costs tied to Mariana Oncology’s newly executed lease.
Arsenal Yards is a mixed‑use, innovation‑driven campus offering more than one million square feet of labs, offices, retail, restaurants and wellness amenities. The master plan includes a cluster of retail and dining destinations, a seven‑screen theater, over 300 residences, a 150‑room hotel and extensive public realm improvements that connect to the nearby Watertown‑Cambridge multi‑use bike path and a revitalized Arsenal Park. Some lab space occupies an original 1800s Arsenal building that features soaring 25‑foot ceilings.
Boylston Properties recently announced that cell therapy developer SQZ Biotech signed a 63,477‑square‑foot lease at Arsenal Yards and will substantially expand its footprint after completing a $72 million Series C and an expanded clinical and commercial collaboration with Roche. Brokerage teams representing the SQZ deal included Cushman & Wakefield’s local executives serving ownership and Newmark Knight Frank brokers representing the tenant. Market observers note that this is part of a cluster of life science leasing momentum in Watertown, with multiple new transactions over the past 18 months.
The Arsenal Yards development is being advanced by Boylston Properties, Wilder and J.P. Morgan. Boylston Properties is a Boston‑based developer with decades of experience in mixed‑use, residential, hotel, corporate and lab buildings in Greater Boston. Wilder is a privately held, owner‑managed retail development, management and leasing firm. J.P. Morgan Asset Management is cited as a global asset manager with broad institutional relationships.
Tishman Speyer’s new debt platform is focused on large, institutional projects in major U.S. markets and will offer debt products that include mezzanine loans, preferred equity, construction financing and purchases of loan portfolios. In Boston, Tishman Speyer is active with the Harvard Enterprise Research Campus in Allston and has previously delivered life science projects through its Breakthrough Properties joint venture, including The 105. Breakthrough Properties also holds sites such as 232 A Street and One Canal in East Cambridge.
Mezzanine lender: Tishman Speyer.
Senior lender: Landesbank Baden‑Württemberg (LBBW).
Borrower: joint venture led by Boylston Properties with institutional investors advised by J.P. Morgan Asset Management.
Debt advisory arrangers: JLL Capital Markets — Brett Paulsrud, Henry Schaffer and Geoff Goldstein.
Observers will be watching how Tishman Speyer’s debt platform deploys capital across mezzanine and preferred structures, and whether the lender expands into construction financing and loan portfolio acquisitions in other U.S. life science and institutional markets. Locally, future leasing at Arsenal Yards and completion of surrounding components of the master plan will signal further validation of Watertown’s growing life science cluster.
The refinancing combined a $25.2 million mezzanine loan from Tishman Speyer and a $94.0 million senior loan from Landesbank Baden‑Württemberg (LBBW).
The borrower is a joint venture led by Boylston Properties alongside institutional investors advised by J.P. Morgan Asset Management.
Proceeds will primarily retire the 2021 construction loan for the fully leased asset and fund leasing costs tied to Mariana Oncology’s new lease.
500 Forge is a three‑story, ~162,000‑square‑foot lab and office building within Arsenal Yards, completed in 2023 and now fully leased to life science tenants.
The mezzanine loan represents the first investment from Tishman Speyer’s new real estate debt platform, which targets institutional projects and offers various debt and equity products.
Yes. SQZ Biotech signed a 63,477‑square‑foot lease and plans to expand at Arsenal Yards after a recent Series C financing and an expanded collaboration with Roche.
| Feature | Details |
|---|---|
| Mezzanine lender | Tishman Speyer — $25.2M |
| Senior lender | Landesbank Baden‑Württemberg (LBBW) — $94.0M |
| Borrower | JV led by Boylston Properties with institutional investors advised by J.P. Morgan Asset Management |
| Property | 500 Forge — three stories, ~162,000 sq ft, completed 2023, fully leased |
| Tenants | Mariana Oncology (Novartis subsidiary), Orna Therapeutics, AvenCell Therapeutics |
| Primary uses of proceeds | Retire 2021 construction loan; fund leasing costs tied to Mariana Oncology’s lease |
| Refinancing arrangers | JLL Capital Markets Debt Advisory — Brett Paulsrud, Henry Schaffer, Geoff Goldstein |
| Tishman Speyer debt platform focus | Institutional‑quality projects in major U.S. cities; mezzanine loans, preferred equity, construction financing, loan portfolio acquisitions |
| Related local leasing | SQZ Biotech — 63,477 sq ft lease at Arsenal Yards; recent $72M Series C and expanded collaboration with Roche |
| Arsenal Yards overview | Mixed‑use campus with 1M+ sq ft of labs/offices/retail, historic building lab spaces, amenities and improved public realm |
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