LEASES
Operating Leases
On September 7, 2021, the Company entered into an indenture of lease (the “1050 Waltham Lease”) with Revolution Labs Owner LLC (the “Landlord”), pursuant to which the Company is leasing approximately 35,662 square feet of office, laboratory and vivarium space located at 1050 Waltham Street, Lexington, Massachusetts (the “Premises”) for its new principal executive office. Base rent was initially fixed at $0.2 million per month and will increase by approximately 3% per annum until the 1050 Waltham Lease expires on November 30, 2031. The Company is obligated to reimburse the Landlord for certain variable costs, including its proportional share of taxes and operating expenses which are not included in the measurement of the 1050 Waltham Lease liability. In connection with its entry into the 1050 Waltham Lease, the Company has provided the Landlord a letter of credit in the amount of approximately $1.2 million, which is recognized as restricted cash within other assets on the consolidated balance sheets. The Company has the option to extend the term of the 1050 Waltham Lease for a period of an additional 5 years. As of December 31, 2025, the Company has no reasonable certainty that this option to extend will be exercised.
In July 2024, the Company entered into a sublease (the “Sublease Agreement”) with Accent Therapeutics, pursuant to which the Company has sublet approximately 20,000 square feet of office and laboratory space located at 1050 Waltham Street, Lexington, Massachusetts, expanding the Company's existing headquarters. Accordingly, the Sublease Agreement for the premises was determined to be classified as an operating lease. Upon commencement of the sublease, the Company recorded an ROU asset of $5.7 million and a lease liability of $5.7 million. The term of the sublease commenced on July 1, 2024 (the "Sublease Commencement Date"). The Sublease Agreement has a term of 5 years and 3 months, measured from the Sublease Commencement Date.
The Company’s obligation for the payment of base rent for the premises began on the Sublease Commencement Date. Base rent was initially fixed at $71.00 per rentable square foot and the Company is only required to pay base rent on 17,500 square feet for the first year of the sublease. The Sublease Agreement also provides for three months of free rent. Base rent will increase by approximately 3% per annum until the Sublease Agreement expires on September 30, 2029.
In connection with its entry into the Sublease Agreement and as a security deposit, the Company provided Accent Therapeutics a letter of credit in the amount of approximately $0.2 million on the Sublease Commencement Date.
The components of the lease cost as of December 31, 2025 and 2024 consisted of the following (in thousands):
YEAR ENDED DECEMBER 31,
20252024
Operating lease cost $4,231 $3,521 
Short-term lease cost281 — 
Variable payments2,0471,554
Total lease cost$6,559 $5,075 
Other information as of December 31, 2025 and 2024 (in thousands):
DECEMBER 31,
20252024
Cash paid for amounts included in the measurement of lease liabilities
        Operating cash flows from operating leases
$3,800 $3,026 
Right-of-use assets obtained in exchange for new operating lease liabilities$— $5,737 

The weighted-average remaining lease term and discount rate for the leases as of December 31, 2025 and 2024 were as follows:
DECEMBER 31,
20252024
Weighted-average remaining lease term — operating leases5.36.3
Weighted-average discount rate — operating leases10.3 %10.3 %
Maturities of operating lease liabilities at December 31, 2025 are as follows (in thousands):
MATURITY OF LEASE LIABILITY
2026$4,002 
20274,125 
20284,251 
20293,983 
20302,903 
20312,734 
Total lease payments21,998 
Less: imputed interest(5,115)
Total operating lease liabilities$16,883 
Included in the consolidated balance sheet:
Current portion of lease liabilities$2,408 
Lease liabilities14,475 
Total operating lease liabilities$16,883 

About Leases Disclosures

Lease disclosures under ASC 842 provide a comprehensive view of a company's leased asset portfolio, including the split between operating and finance leases, discount rates used to present-value future payments, and the maturity schedule of lease obligations. This section reveals a significant source of off-balance-sheet commitments that were largely hidden before the current standard.

Key signals: the weighted-average discount rate affects the size of recorded lease liabilities — a higher rate reduces the reported obligation, so compare the chosen rate against the company's incremental borrowing rate. The operating versus finance lease mix affects both EBITDA and operating income presentation. Watch the maturity table for concentration risk: large payment cliffs in specific years may create cash flow pressure. Variable lease payments excluded from the liability measurement represent real obligations that do not appear on the balance sheet. Compare total lease costs against prior-year operating lease expense to assess the true economic burden.