In June 2012, the Company entered into a master lease for the Company’s corporate office headquarters in Boston, Massachusetts, which was originally set to expire in August 2016, but renewed through August 31, 2021. As of September 30, 2021 and December 31, 2020, a total security deposit of $0.1 million is included in deposits on the Company’s balance sheet.

On April 22, 2021, the Company extended its lease for a 9,800 square foot portion of its office space in Boston. The renewal for its office space was originally set to expire on August 31, 2021, but has now been extended through August 2026. Under the terms of the renewal, the Company is required to make rental payments of approximately $26,000 per month.

On January 30, 2018, the Company entered into a lease agreement for office space in Houston, Texas, at MD Anderson. Under the terms of the Houston lease agreement, the Company leased approximately 210 square feet and were required to make rental payments at an average monthly rate of approximately $1,000. This lease was terminated effective March 31, 2020.

On March 12, 2019, the Company entered into a lease agreement, or the First Houston Lease, for office and lab space in Houston, Texas at MD Anderson through April 2021. Under the terms of the First Houston Lease agreement, the Company leased approximately 1,038 square feet and was required to make rental payments at an average monthly rate of approximately $2,000 through April 2021. On October 15, 2019, the Company entered into a lease agreement, or the Second Houston Lease, for additional office space in Houston through February 2027. Under the terms of the Second Houston Lease, the Company leases from MD Anderson, approximately 8,443 square feet and is initially required to make rental payments of approximately $17,000 per month through February 2027, subject to an annual base rent increase of approximately 3.0% throughout the term. Effective April 13, 2020, the Company leased an additional 5,584 square feet from MD Anderson. The Company is initially required to make rental payments of approximately $12,000 per month through February 2027, subject to an annual base rent increase of approximately 3.0% throughout the term.

Effective December 15, 2020, the Company leased an additional 35,482 square feet from MD Anderson. The Company is initially required to make rental payments of approximately $37,000 per month through April 2028, subject to an annual base rent increase of approximately 3.0% throughout the term beginning in April 2023.

The components of lease expense were as follows:


	Three Months Ended September 30,						For the Nine Months Ended September 30,
(in thousands)	2021			2020			2021			2020
Operating lease cost	$	352		$	267		$	1,113		$	768
Total lease cost	$	352		$	267		$	1,113		$	768
Weighted-average remaining lease term (years)		5.71		4.99				5.71		4.99
Weighted-average discount rate		8.00	%		8.00	%		8.00	%		8.00	%

Effective June 1, 2020, the Company entered into a noncancelable lease for a period of less than a year with monthly payments of approximately $10,000 that is not subject to right of use asset recognition under ASC 842. Effective September 1, 2020, the Company added additional space to the noncancelable lease for a period of less than a year with monthly payments now totaling approximately $15,000. Rent expense was zero and $5,000 during the three and nine months ended September 30, 2021, respectively. As of September 30, 2021, this lease has been terminated and the Company has no further obligation.

As of September 30, 2021, the future minimum lease payments of the Company’s operating lease obligations for the years ended December 31, were as follows (in thousands):


2021 (excluding the nine months ended September 30, 2021)	$	273
2022		1,102
2023		1,132
2024		1,166
2025		1,201
Thereafter		1,873
Total lease payments		6,747
Less: Imputed interest and adjustments		(1,329	)
Present value of lease payments	$	5,418