Upstream Bio Inc

Our corporate headquarters is presently located in Waltham, Massachusetts, where we lease and occupy 16,801 square feet of office space. The initial term of the lease expires on November 1, 2027, with an option to extend the lease for an additional three years thereafter. We previously leased and occupied 8,146 square feet of office space and subleased an additional 3,405 square feet of office space in Waltham, Massachusetts. The initial term of this lease and sublease expired on June 30, 2023 and 2024, respectively, with an option to continue each thereafter on a month to month basis unless terminated by either party upon written notice. In July 2024, we provided written notice of our intent to terminate this lease and sublease.

We believe that our leased premises will be sufficient for our needs for the foreseeable future. To meet the future needs of our business, we may lease additional or alternate space, and we believe suitable additional or alternative space will be available in the future on commercially reasonable terms.