Rent expense was $47,000 and $46,000 for the three months ended June 30, 2022 and 2021, respectively. Rent expense was $93,000 and $87,000 for the six months ended June 30, 2022 and 2021, respectively.

From May 2019 through April 30, 2022, the Company leased 4,677 square feet of office space in San Diego, California. On April 18, 2022, the Company entered into a sublease agreement for office space of 3,748 square feet in San Diego, California which expires on July 31, 2023 (the “San Diego Lease”). Base rent under the San Diego Lease is approximately $157,000 annually and the monthly rent expense is being recognized on a straight-line basis over the term of the lease.

The San Diego Lease is included in the accompanying condensed consolidated balance sheet at the present value of the lease payments. As the San Diego Lease does not have an implicit interest rate, the present value reflects a 10.0% discount rate which is the estimated rate of interest that the Company would have to pay in order to borrow an

amount equal to the lease payments on a collateralized basis over a similar term and in a similar economic environment. The Company recognized a net operating lease right-of-use asset and an aggregate lease liability of $157,000 as of June 30, 2022. The weighted average remaining lease term was 1.1 years.

Maturities of the lease liability due under this lease agreement as of June 30, 2022, are as follows (in thousands):


Maturity of lease liability	Operating Lease
2022	$	79
2023 (7 months)		92
Total lease payments		171
Less imputed interest		(14	)
Lease liability		157
Less current portion of lease liability		(144	)
Lease liability	$	13

Effective in September 2019, the Company and Shanghai Pharmaceutical (USA) Inc. (“SPH USA”), the Company’s largest stockholder and an affiliate of two of the Company’s directors, entered into a Materials and Supply and Services Agreement (“SPH USA Services Agreement”). Pursuant to the SPH USA Services Agreement, the Company and SPH USA have executed and expect to continue to execute various statements of work for the transfer to SPH USA of key reagents and other materials, and for the supply of certain services by the Company to SPH USA, as contemplated under and in furtherance of a license and distribution agreement between the parties (see Note 4). The Company recorded amounts receivable from SPH USA, in prepaid and other assets, related to statements of work totaling $0.1 million and $0.4 million as of June 30, 2022 and December 31, 2021, respectively. The Company has an agreement with SPH USA for certain rights to the greater China area (see Note 4).