We have a total of four operating leases as of March 31, 2022 with remaining lease terms of approximately 4 to 8 years.

In June 2021, we entered into a sublease agreement for office space in Seattle, Washington (“Seattle Sublease”), which we use as our corporate headquarters. The Seattle Sublease commenced on July 1, 2021 and continues for a period of 58 months. The aggregate estimated base rent payments due over the remaining term of the Seattle Sublease is approximately $5.0 million.

As of March 31, 2022, we are subleasing approximately 112,000 square feet in one of our facilities. Sublease income was $2.0 million and $1.4 million for the three months ended March 31, 2022 and 2021, respectively, which was netted against rent expense. Total sublease income to be earned, in aggregate, will be approximately $63.1 million over the remaining term of the sublease agreement.

We maintain a letter of credit as security for a facility lease that expires in 2029. The letter of credit is collateralized by a certificate of deposit in the amount of $1.8 million, which is classified as long-term restricted cash in our condensed consolidated balance sheet as of March 31, 2022. Additionally, we maintain a letter of credit as a security deposit for a facility lease that expires in 2026. The letter of credit is collateralized by a certificate of deposit in the amount of $0.3 million, which is classified as long-term restricted cash in our condensed consolidated balance sheet as of March 31, 2022.

The maturity of our operating lease liabilities as of March 31, 2022 is as follows (in thousands):

Undiscounted Lease Payments	Amounts
2022 (remaining nine months)	$	5,684
2023		7,716
2024		7,871
2025		8,030
2026		7,179
Thereafter		18,934
Total undiscounted lease payments		55,414
Present value adjustment		(12,372	)
Total net lease liability	$	43,042
Net lease liability - current	$	4,581
Net lease liability - non-current		38,461
Total net lease liability	$	43,042

Rent expense recognized for operating leases was $2.3 million and $2.1 million for the three months ended March 31, 2022 and 2021, respectively. Variable lease payments, including non-lease components such as common area maintenance fees, recognized as rent expense for operating leases were $0.8 million and less than $0.6 million for the three months ended March 31, 2022 and 2021, respectively.

The following summarizes additional information related to our operating leases:

	March 31, 2022		December 31, 2021
Weighted-average remaining lease terms (in years)
Operating leases		7.2		7.4
Weighted-average discount rate
Operating leases	7.5%		7.5%

In the ordinary course of business, we enter into agreements that may include indemnification provisions. Pursuant to such agreements, we may indemnify, hold harmless and defend an indemnified party for losses suffered or incurred by the indemnified party. Some of the provisions will limit losses to those arising from third party actions. In some cases, the indemnification will continue after the termination of the agreement. The maximum potential amount of future payments we could be required to make

under these provisions is not determinable. We have never incurred material costs to defend lawsuits or settle claims related to these indemnification provisions. We have also entered into indemnification agreements with our directors and officers that require us, among other things, to indemnify them against certain liabilities that may arise by reason of their status or service as directors or officers to the fullest extent permitted by Delaware corporate law. We currently maintain directors’ and officers’ liability insurance.

From time to time, we may become involved in litigation relating to claims arising from the ordinary course of business. Management believes that there are no actions pending against us currently, the ultimate disposition of which would have a material adverse effect on our results of operations, financial condition or cash flows.

We have various manufacturing, clinical, research and other contracts with vendors in the conduct of the normal course of our business. All contracts are terminable, with varying provisions regarding termination. If a contract with a specific vendor were to be terminated, we would only be obligated for the products or services that we had received at the time the termination became effective as well as non-cancelable and non-refundable obligations, including payment obligations for costs or expenses incurred by the vendor for products or services before the termination became effective. In the case of terminating a clinical trial agreement at a particular site, we would also be obligated to provide continued support for appropriate medical procedures at that site until completion or termination.