In June 2012, the Company entered into a master lease for the Company’s office in Boston, Massachusetts, which was originally set to expire in August 2016, but was renewed through August 31, 2021. On April 22, 2021, the Company extended its lease for a portion of office space in Boston. The renewal of the portion of the Company's office space was originally set to expire on August 31, 2021, but was extended through August 31, 2026. As of December 31, 2022, and December 31, 2021, a total security deposit of $0.1 million is included in deposits on the Company’s balance sheet. In December 2021, the Company made the decision to move its operations away from its former corporate office in Boston. As described in Note 3, Summary of Significant Accounting Policies, the Company's change in the intended use of the Boston office represented an indicator of impairment. The Company determined the aggregate carrying value of the asset group (approximately $1.4 million as of December 31, 2021) was in excess of the aggregate estimated fair value and recorded an impairment charge of $0.6 million to the right-of-use asset and approximately $0.1 million to associated property and equipment during the year ended December 31, 2021. The fair value was determined based on the amount and timing of estimated net future cash flows, discounted at a risk-adjusted rate of 10%.

On March 12, 2019, the Company entered into a lease agreement for office and lab space in Houston, Texas at MD Anderson through April 2021. Under the terms of the lease agreement, the Company leases approximately 1,038 square feet and was required to make rental payments

at an average monthly rate of approximately $2 thousand through April 2021. On October 15, 2019, the Company entered into a lease agreement for additional office and laboratory space in Houston through February 2027. Under the terms of the lease, the Company leases from MD Anderson, approximately 8,443 square feet and is initially required to make rental payments of approximately $17 thousand per month through February 2027, subject to an annual base rent increase of approximately 3.0% throughout the term. Effective April 7, 2020, the Company leased an additional 5,594 square feet from MD Anderson. The Company is initially required to make rental payments of approximately $12 thousand per month through February 2027, subject to an annual base rent increase of approximately 3.0% throughout the term.

On December 15, 2020, the Company entered into a second agreement with MD Anderson to lease additional space on MD Anderson’s campus (the “2020 Lease”). The Company is initially required to make rental payments of approximately $37 thousand per month through April 2028, subject to an annual base rent increase of approximately 3.0% throughout the term beginning in April 2023. The 2020 Lease may be extended for one additional five-year term at the Company's election.

In April 2022, the Company modified the 2020 Lease, which reduced the Company's leased space from 18,111 square feet to 3,228 square feet. As a result, the associated lease liability and right-of-use asset were remeasured to $0.4 million based on revised lease payments. A gain of $0.1 million was recorded on the lease modification during the year ended December 31, 2022. The Company is initially required to make payments of approximately $7 thousand per month through April 2028, subject to an annual base rent increase of approximately 3.0% throughout the term. The 2020 Lease may be extended for one additional five-year term at the Company's election.

The components of lease expense were as follows:


	Year Ended December 31,
($ in thousands)	2022			2021
Operating lease cost	$	756		$	1,394
Total lease cost	$	756		$	1,394
Weighted-average remaining lease term (years)		4.13			5.58
Weighted-average discount rate		8.26	%		8.00	%

The Company paid $0.8 million for amounts included in the measurement of the lease liabilities for the year-ended December 31, 2022. The Company did not recognize new operating lease assets obtained in exchange for operating lease liabilities for the year-ended December 31, 2022.

As of December 31, 2022, the maturities of the Company’s operating lease liabilities were as follows (in thousands):


Maturity of Lease Liabilities	Operating Leases
2023		757
2024		780
2025		804
2026		712
2027		158
Thereafter		31
Total lease payments		3,242
Less: imputed interest		(496	)
Present value of lease payments	$	2,746

In June 2022, the Company executed an agreement to sub-sublease 4,772 square feet of subleased office space in Boston. The term of the sub-sublease is from July 1, 2022 to June 30, 2025 and provides the sub-subtenant with an option to extend through to July 31, 2026. For the year ended December 31, 2022, the Company recognized $0.1 million in lease income, which is classified within other income (expense), net in the Statement of Operations. Under the current terms of the agreement, lease income for the remainder of the sub-sublease term is expected to be $0.2 million in 2023, $0.2 million in 2024 and $0.1 million in 2025.