FIRST AMENDMENT TO OFFICE LEASE AGREEMENT

Exhibit 10.3.1

FIRST AMENDMENT TO OFFICE LEASE AGREEMENT

     THIS FIRST AMENDMENT TO OFFICE LEASE AGREEMENT (“First Amendment”) is made this 10th day of May, 2002, by and between CHASE TOWER ASSOCIATES, L.L.C., a Delaware limited liability company (“Landlord”), and CAPITALSOURCE FINANCE LLC, a Delaware limited liability company (“Tenant”).

W I T N E S S E T H:

     WHEREAS, by that certain Office Lease Agreement dated December 8, 2000 (the “Lease”), Landlord leased to Tenant, and Tenant leased from Landlord, approximately 16,799 square feet of rentable area on the twelfth (12th) floor, known as Suite 1200 (the “Original Premises”), in the building located at 4445 Willard Avenue, Chevy Chase, Maryland (the “Building”), upon the terms and conditions set forth in the Lease;

     WHEREAS, Tenant desires to lease from Landlord, and Landlord desires to lease to Tenant, an additional 7,463 rentable square feet of space located on the eleventh (11th) floor of the Building and known as Suite 1130 (the “Expansion Space”), and the parties desire to extend the term of the Lease with respect to the Original Premises upon the terms and conditions hereinafter set forth;

     WHEREAS, the Original Premises and the Expansion Space are hereinafter collectively referred to as the “Premises”; and

     WHEREAS, Landlord and Tenant desire to amend the Lease to reflect their understanding and agreement with regard to the lease of such additional space, and to otherwise amend the Lease, as more particularly set forth herein.

     NOW, THEREFORE, for and in consideration of the mutual promises herein contained, and other good and valuable consideration, the receipt and sufficiency of which are hereby acknowledged, the parties hereto mutually agree as follows:

     1. Any capitalized terms used in this First Amendment and not otherwise defined herein shall have the meanings ascribed to them in the Lease.

     2. The Term of the Lease is hereby extended for the period (such period being hereinafter referred to as the “Extension Period”) commencing on November 1, 2011 (the “Extension Period Commencement Date”) and continuing through and including August 14, 2012 (the “Extension Period Expiration Date”), as hereinafter defined, unless earlier terminated pursuant to the provisions of the Lease as modified by the provisions of this First Amendment, or pursuant to law.

     3. The definition of “Premises” in Section 1.2 of the Lease is hereby amended with respect to all periods beginning on and after the Expansion Space Commencement Date (as hereinafter defined) by inserting the following language at the end thereof:

     “Notwithstanding the foregoing, commencing on the Expansion Space Commencement Date, as hereinafter defined, the Expansion Space shall be deemed a part of the Premises, and thereafter the Premises shall consist of approximately 24,262 square feet of rentable space.”

     4. The definition of “Operating Charges Base Year” in Section 1.7 of the Lease is hereby amended by inserting the following language at the end thereof:

     “Notwithstanding the foregoing, commencing on the Expansion Space Commencement Date, as hereinafter defined, the Operating Charges Base Year shall be Calendar year 2003.”

     5. The definition of “Real Estate Taxes Base Year” in Section 1.8 of the Lease is hereby amended by inserting the following language at the end thereof:

     “Notwithstanding the foregoing, commencing on the Expansion Space Commencement Date, as hereinafter defined, the Real Estate Taxes Base Year shall be Calendar year 2003.”

     6. The definition of “Parking Permits” in Section 1.17 of the Lease is hereby amended with respect to all periods beginning on and after the Expansion Space Commencement Date (as hereinafter defined) by inserting the following language at the end thereof:

     “Notwithstanding the foregoing, commencing on the Expansion Space Commencement Date, as hereinafter defined, Tenant shall have the right to use forty-three (43) Parking Permits as provided in Article XXIV of this Lease.”

     7. As if the Expansion Space Commencement Date, as hereinafter defined, “Premises” as used in Article V of the Lease (captioned “Increase in Operating Expenses and Real Estate Taxes”) shall mean the Original Premises and the Expansion Space. Article V of the Lease is hereby amended as follows:

     (i) Section 5.2 is amended by deleting therefrom the language: “Commencing on the first anniversary of the Lease Commencement Date” and inserting in lieu thereof the language:

“Commencing on the first anniversary of the Expansion Space Commencement Date”.

     (ii) Section 5.2(b) is hereby amended by deleting all of the language therefrom and inserting in lieu thereof the following language:

“(b) If the average occupancy rate for the Building during any calendar year (including the Operating Charges Base Year and the Real Estate Taxes Base Year) is less than one hundred percent (100%) or, solely with respect to Operating Expenses, if any tenant is separately paying for (or does not require) electricity or janitorial services to be furnished to its premises, then (i) Operating Expenses for such year shall be deemed to include all additional expenses, as reasonably estimated by Landlord, which would have been incurred during such year if such average occupancy rate had been one hundred percent (100%) and if Landlord paid for electricity and

janitorial services furnished to such premises, and (ii) Real Estate Taxes for such year shall be deemed to include all additional Real Estate Taxes, as reasonably estimated by Landlord, which would have been incurred during such year if such average occupancy rate had been one hundred percent (100%). In no event shall the provisions of this paragraph be used to enable Landlord to collect from the tenants of the Building more than one hundred percent (100%) of the costs and expenses incurred by Landlord in owning, managing, maintaining, repairing, operating and cleaning the Building and the Land or more than one hundred percent (100%) of the Real Estate Taxes.”

     (iii) Section 5.3 is amended by deleting therefrom the language “Commencin