The Company leases office and laboratory space in Wilmington, Delaware under a noncancelable lease (the “Lease”), which expires in December 2022. The Lease was amended during the third quarter of 2021 to include additional office and laboratory space to accommodate the Company’s growth. The Company has an option to renew the Lease for an additional 1-year period. This option to extend was not recognized as part of the Company’s measurement of the right-of-use asset and operating lease liability as of December 31, 2021. The discount rate used to account for the Company’s operating lease under ASC 842 is the Company’s estimated incremental borrowing rate of 10.0%.

The future minimum lease payments under the Lease at December 31, 2021 are as follows:

(in thousands)
2022	$	1,836
Total undiscounted lease payments		1,836
Less imputed interest		(96	)
Current lease liability	$	1,740

During the fourth quarter of 2021, the Company entered into a lease agreement (the Chestnut Run Lease) with a commencement date of the earlier of (i) the Landlord Work Substantial Completion Date (as such term is defined in the Chestnut Run Lease), or (ii) the date the Company takes possession of the premises for the conduct of the Company’s business (the Commencement Date). The Chestnut Run Lease premises includes approximately 81,000 square feet, located at Chestnut Run Plaza in Wilmington, Delaware (the Premises). The Premises contains both office and lab space the Company intends to use for administrative, research and development and other activities. Upon the Chestnut Run Lease commencement, the Company will recognize a right-of-use asset and operating lease liability in accordance with ASC 842. The Chestnut Run Lease has an initial term of 162 months with 3 five-year extension options and certain expansion rights. The aggregate estimated rent payments due over the initial term of the Chestnut Run Lease is approximately $33.8 million. The estimated rent payments due over the next five years is as follows:

(in thousands)
2022	$	-
2023		840
2024		2,141
2025		2,350
2026		2,409
Thereafter		26,098

The Company paid a security deposit in the form of a letter of credit of $4.0 million which is included in the balance sheet as restricted cash as of December 31, 2021. The security deposit may be reduced to $0.5 million over time in accordance with the terms of the Chestnut Run Lease.

In June 2021, the Company entered into a 12-month noncancelable lease, which commenced on July 1, 2021 and will expire on June 30, 2022, and has remaining lease payments of approximately $0.2 million in 2022. The Company adopted the short-term lease election as afforded by ASC 842 and did not recognize a right-of-use asset and operating lease liability related to this short-term lease.

Rent expense for the years ended December 31, 2021 and 2020 was $1.8 million and $1.2 million, respectively.

The Company entered into employment agreements with key personnel providing for compensation and severance in certain circumstances, as defined in the respective employment agreements.

The Company sponsors a 401(k) defined‑contribution plan covering all employees. Participants are permitted to contribute up to 100% of their eligible annual pretax compensation up to an established federal limit on aggregate participant contributions. The Company provides a safe harbor match with a maximum amount of 3% of the participant’s compensation. During 2021 the Company made matching contributions of $0.5 million. The Company did not make any matching contributions in 2020.

In September 2021, the Company entered into a research collaboration agreement estimated to last for approximately one year (the “Darwin Health Agreement”) with Darwin Health, Inc. (“DarwinHealth”). Under the terms of the Darwin Health Agreement, DarwinHealth will utilize their drug discovery technologies and certified methodologies in precision oncology to advance and accelerate clinical development for certain of the Company’s programs across a broad range of tumor subtypes. The Company will pay DarwinHealth a total of $3.0 million in three equal installments over the one-year term (the “Research Term”) to fund the research and, if the Company adopts any of DarwinHealth’s development ideas, the Company will be responsible for the development, manufacturing, and commercialization of any such products. For the year ended December 31, 2021, research and development expense related to this agreement recognized in the statement of operations was $1.0 million. In addition to research funding, DarwinHealth is eligible to receive future research, development and regulatory milestones of up to $3.0 million for each product candidate and is also eligible to receive tiered royalties in the low single digits on net sales of each product developed using DarwinHealth’s development technologies or methods. However, within eighteen-months following the Research Term, the Company, in its sole discretion, may notify DarwinHealth that it will not utilize its development ideas and will be entitled to receive a refund of $0.5 million.

The Company enters into agreements with contract research organizations (“CROs”) to assist in the performance of research and development activities. Expenditures to CROs will represent a significant cost in clinical development for the Company.