SIXTH AMENDMENT TO OFFICE LEASE

Exhibit 10.7

SIXTH AMENDMENT TO OFFICE LEASE

THIS SIXTH AMENDMENT TO OFFICE LEASE (this “Amendment”) is made and effective as of December 22, 2006 (the “Effective Date”) by and between MAGUIRE PROPERTIES-SAN DIEGO TECH CENTER, LLC, a Delaware limited liability company (“Landlord”), and KINTERA, INC., a Delaware corporation (“Tenant”).

RECITALS

A. Landlord is the owner of that certain improved real property located at 9605 Scranton Road Drive, San Diego, California (referred to herein alternatively as “Building 1” or the “Building”). Building 1 is a part of that certain project, with all common areas and appurtenant parking facilities, commonly known as the “San Diego Tech Center” (the “Project”).

B. San Diego Tech Center, LLC, a Delaware limited liability company ( “SDTC” ), predecessor-in-interest to Calwest (defined below), as landlord, and Tenant, as tenant, entered into that certain Office Building Lease dated as of August 7, 2000 (the “Original Lease” ), as amended by (i) that certain First Amendment to Lease dated November 1, 2000 (the “First Amendment”) by and between Calwest Industrial Properties, LLC (“Calwest”), successor-in-interest to SDTC and predecessor-in-interest to Landlord, as landlord, and Tenant, as tenant, (ii) that certain Second Amendment to Lease dated June 24, 2002 (the “Second Amendment”) by and between Calwest, as landlord, and Tenant, as tenant, (iii) that certain Third Amendment to Lease dated February 13, 2004 (the “Third Amendment”) by and between Calwest, as landlord, and Tenant, as tenant, (iv) that certain Fourth Amendment to Lease dated April 1, 2005 (the “Fourth Amendment”) by and between Calwest, as landlord, and Tenant, as tenant, and (v) that certain Fifth Amendment to Lease dated December 1, 2006 (the “Fifth Amendment”) by and between Landlord, as landlord, and Tenant, as tenant. The Original Lease as amended by the First Amendment, the Second Amendment, the Third Amendment, the Fourth Amendment and the Fifth Amendment are collectively referred to herein as the “Lease” .

C. Pursuant to the Lease, Tenant has certain rights to use and occupy (i) that certain premises consisting of all of the second (2nd) Floor of the Building consisting of approximately 20,543 rentable square feet (approximately 18,345 usable square feet) (the “Second Floor Premises”), as more particularly described in the Fifth Amendment and (ii) that certain premises consisting of a portion of the third floor of the Building commonly known as Suite 310 and consisting of approximately 7,350 rentable square feet (approximately 6,608 usable square feet) (the “Suite 310 Premises”), as more particularly described in the Fifth Amendment. The Second Floor Premises and the Suite 310 Premises may from time to time be referred to herein collectively, as the “Existing Premises”.

D. Landlord and Tenant hereby desire by this Amendment to (i) add to the Existing Premises as of the First Increment Sixth Floor Premises Commencement Date, that certain space in the Building consisting of approximately 3,552 rentable square feet (the “First Increment Sixth Floor Premises”) as more particularly shown on Exhibit “A”, attached hereto, (ii) additionally add to the Premises as of the Second Increment Sixth Floor Premises Commencement Date, that certain space in the Building consisting of approximately 6,218 rentable square feet (the “Second Increment Sixth Floor Premises”) as more particularly shown on Exhibit “A” , attached hereto and (iii) further amend the Lease upon and subject to each of the terms, conditions, and provisions set forth herein. The First Increment Sixth Floor Premises and the Second Increment Sixth Floor Premises consists of approximate 9,770 rentable square feet (approximately 8,821 usable square feet) in the aggregate.

F. All capitalized terms used herein without definition are defined as set forth in the Lease.

NOW, THEREFORE, in consideration of the Recitals set forth above, the agreements set forth below and other good and valuable consideration, the receipt and sufficiency of which are hereby acknowledged, Landlord and Tenant hereby agree as follows:

1. Amendment .

1.1 Amendments to Fifth Amendment .

(a) Amendment of Substantial Completion Date and New Rent Commencement Date . The parties hereto agree that for purposes of the Fifth Amendment and the Work Letter (defined in Section 1.6, below), and for purposes of this Amendment, (a) the “Substantial Completion Date” shall be the date on which Substantial Completion (as defined in the Work Letter (defined in Section 1.6, below)) of both the Fifth Amendment Tenant Improvements (as defined in the Work Letter) and the Sixth Floor Tenant Improvements (defined in Section 1.6, below) (collectively, the “Fifth and Sixth Amendment Tenant Improvements”), occurs or is deemed to occur as provided in Section 1.2(a) of the Fifth Amendment and (b) that the New Rent Commencement Date (as defined in the Fifth Amendment) shall be the date that is five (5) days, including a weekend, after the earlier to occur of (i) the Substantial Completion Date (as defined above) and the Outside Start Date (as defined in the Fifth Amendment).

(b) Deletion of Section 1.1; Continued Use of Sixth Floor Premises . The parties hereto acknowledge and agree that Section 1.1 of the Fifth Amendment is hereafter null and void and shall be of no further force or effect. For the avoidance of doubt, the parties hereto agree that, notwithstanding anything to the contrary in the Fifth Amendment, Tenant shall have the right to continue to use and occupy the Sixth Floor Premises in accordance with this Amendment, before, during after the construction of the Fifth and Sixth Amendment Tenant Improvements.

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1.2 Addition of Sixth Floor Premises .

(a) First Increment Sixth Floor Premises .

(i) Commencing on First Increment Sixth Floor Premises Commencement Date (defined below), the First Increment Sixth Floor Premises shall be added to the Premises, and following the First Increment Sixth Floor Premises Commencement Date, all references in the Lease to “Premises” shall include the First Increment Sixth Floor Premises. The “First Increment Sixth Floor Premises Commencement Date” means the New Rent Commencement Date (as defined in Section 1.1, above).

(ii) The term of Tenant’s lease of the First Increment Sixth Floor Premises (the “First Increment Sixth Floor Premises Term”) shall commence on the First Increment Sixth Floor Premises Commencement Date and shall expire on the Extended Term Expiration Date (as defined in the Fifth Amendment).

(iii) Following the First Increment Sixth Floor Premises Commencement Date, all references in the Lease to the “Premises” shall mean and refer to the Existing Premises and the First Increment Sixth Floor Premises, collectively, and the “Premises” shall consist of a total of approximately 31,445 rentable square feet in the aggregate.

(b) Second Increment Sixth Floor Premises .

(i) Commencing on Second Increment Sixth Floor Premises Commencement Date (defined below), the Second Increment Sixth Floor Premises shall be added to the Premises, and following the Second Increment Sixth Floor Premises Commencement Date, all references in the Lease to “Premises” shall include the Second Increment Sixth Floor Premises. The “Second Increment Sixth Floor Premises Commencement Date” means the earlier to occur of (A) July 1, 2008, or (B) the date that is six (6) months after the first day upon which 275 or more persons employed by Tenant (or any subtenant or other transferee of Tenant) occupy or use the Premises. For purposes of determining when the Second Increment Sixth Floor Premises Commencement Date shall occur, Tenant shall (A) deliver to Landlord on or before the first (1 ^st ) day of each calendar month after the New Rent Commencement Date (and prior to the day that is six months after the date on which 275 or more persons employed by Tenant (or any subtenant or other transferee of Tenant) first begin occupying or using the Premises), a written notice certified by an officer of Tenant setting forth the number of persons employed by Tenant (or any subtenant or other transferee of Tenant that are at such time using or occupying the Premises and (B) shall notify Landlord promptly following the first day on which 275 or more persons employed by Tenant (or any subtenant or other transferee of Tenant) begin occupying or using the Premises. Landlord agrees that information provided by Tenant to Landlord under this Section 1.2(b)(i) shall be subject to Section 2 below treated as confidential and shall not be disclosed by Landlord other than as permitted under Section 2, below.

(ii) The term of Tenant’s lease of the Second Increment Sixth Floor Premises (the “Second Increment Sixth Floor Premises Term”) shall commence on the Second Increment Sixth Floor Premises Commencement Date and shall expire on the Extended Term Expiration Date.

(iii) Following the Second Increment Sixth Floor Premises Commencement Date, all references in the Lease to the “Premises” shall mean and refer to the Existing Premises and the Sixth Floor Premises (defined below), collectively, and the “Premises” shall consist of a total of approximately 37,663 rentable square feet in the aggregate. The “Sixth Floor Premises” means, collectively, the First Increment Sixth Floor Premises and the Second Increment Sixth Floor Premises.

1.3 Early Occupancy of Second Increment Sixth Floor Premises . Landlord hereby agrees that, Landlord shall also permit Tenant to occupy and use the Second Increment Sixth Floor Premises during the period (the “Second Increment Sixth Floor Beneficial Occupancy Period” ) after the New Rent Commencement Date and prior to the Second Increment Sixth Floor Premises Commencement Date. During the Sixth Floor Beneficial Occupancy Period, each and every term of the Lease (as amended hereby) shall apply to Tenant’s use and occupancy of the Second Increment Sixth Floor Premises; provided, however that the parties hereto acknowledge and agree that, notwithstanding Tenant’s use and occupancy of the Second Increment Sixth Floor Premises prior to the Second Increment Sixth Floor Premises Commencement Date, Tenant shall have no obligation to pay Rent or Additional Charges with respect to the Second Increment Sixth Floor Premises during the Second Increment Sixth Floor Premises Beneficial Occupancy Period.

1.4 Rent .

(a) Prior to Substantial Completion . During the portion of the Term commencing on the Effective Date and continuing through and including the New Rent Commencement

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Date (including any portion of the Extended Term (as defined in the Fifth Amendment) prior to the New Rent Commencement Date), Tenant shall continue to pay Rent to Landlord with respect to the Premises in the amounts required and in the manner required under Section 1.4(a) of the Fifth Amendment.

(b) First Increment Sixth Floor Premises . Commencing on the First Increment Sixth Floor Premises Commencement Date and continuing through the Extended Term, the Rent payable with respect to the First Increment Sixth Floor Premises shall be as follows and shall be payable in accordance with and subject to the procedures set forth in Article 4 of the Original Lease:

(c) Second Increment Sixth Floor Premises . Commencing on the Second Increment Sixth Floor Premises Commencement Date and continuing through the Extended Term, the Rent payable with respect to the Second Increment Sixth Floor Premises shall be as follows and shall be payable in accordance with and subject to the procedures set forth in Article 4 of the Original Lease:

1.5 Additional Charges . During the Term (as extended by the Extended Term), Tenant shall continue to pay to Landlord as Additional Charges, Tenant’s Building Share of Excess Building Expenses and Tenant’s Project Share of Excess Project Expenses, all in accordance with the provisions of the Lease (including, without limitation, all of the provisions of Section 1.5 of the Fifth Amendment) as amended hereby.

(a) The parties hereto agree that, as provided in Section 1.5(b) of the Fifth Amendment, during the portion of the Term commencing on the Effective Date and continuing through and including the day immediately preceding the New Rent Commencement Date (including any portion of the Extended Term prior to the New Rent Commencement Date), calculation of Tenant’s Building Share of Excess Building Expenses and Tenant’s Project Share of Excess Project Expenses shall be based on the Tenant’s Building Share and Tenant’s Project Share, respectively, as set forth in the Lease (prior to the Fifth Amendment and prior to this Amendment), notwithstanding that Tenant may be occupying premises within the Building and Project that does not compute to Tenant’s Building Share or Tenant’s Project Share (as set forth in the Lease, prior to the Fifth Amendment and this Amendment).

(b) The parties hereto acknowledge and agree that, commencing on the First Increment Sixth Floor Premises Commencement Date (notwithstanding anything in the Fifth

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Amendment to the contrary), (i) the Tenant’s Building Share (as set forth in Section 5.1(e) of the Original Lease) shall mean 19.76% (31,445 rsf/159,165 rsf) and (ii) the Tenant’s Project Share (as set forth in Section 5.1(f) of the Original Lease) shall mean 4.86% (31,445 rsf/647,229 rsf).

(c) The parties hereto acknowledge and agree that, commencing on the Second Increment Sixth Floor Premises Commencement Date (notwithstanding anything in the Fifth Amendment to the contrary), (i) the Tenant’s Building Share (as set forth in Section 5.1(e) of the Original Lease) shall mean 23.66% (37,663 rsf/159,165 rsf) and (ii) the Tenant’s Project Share (as set forth in Section 5.1(f) of the Original Lease) shall mean 5.82% (37,663 rsf/647,229 rsf).

(d) For the avoidance of doubt, the parties hereto agree that Section 1.5(e) of the Fifth Amendment shall apply to the entire Premises (i.e, the Existing Premises together with the Sixth Floor Premises (and any further expansions of the Premises that may occur after the date hereof)).

1.6 Landlord’s Construction of the Sixth Floor Tenant Improvements; Condition of the Premises; Coordination of Construction .

(a) Landlord’s sole construction obligation in connection with this Amendment is as set forth in this Amendment (and in the Work Letter as modified hereby). The parties hereto agree that: (i) the construction of its initial tenant improvements, if any, in the Sixth Floor Premises (the “Sixth Floor Tenant Improvements”) shall be governed by in the Work Letter attached as Exhibit “B” to the Fifth Amendment (the “Work Letter” ); (ii) for purposes of the Work Letter, from and after the date hereof all references in the Work Letter to the Fifth Amendment Tenant Improvements shall be deemed to be references to the Fifth and Sixth Amendment Tenant Improvements; (iii) all references in Sections 3.4(a), 3.4(b), 5.1 and Exhibit B-l of the Work Letter to the Suite 310 Premises shall be deemed to also be references to the Sixth Floor Premises and (iv) except as specifically provided otherwise in this Amendment (or in the Work Letter as amended hereby), Landlord shall have no obligation, (A) to make any improvements, alterations or other modifications to the Sixth Floor Premises, or (B) to provide Tenant any allowance, rent credit or abatement in connection with Tenant’s entering into this Amendment.

(b) In connection with Tenant’s lease of the Sixth Floor Premises, Landlord shall provide to Tenant an improvement allowance in an amount of $320,898.50. Accordingly, the Allowance Amount (as defined in the Work Letter) is hereby increased from $432,341.50 to $753,240.00.

(c) Landlord agrees that Landlord shall cause the Sixth Floor Tenant Improvements to be constructed either prior to or concurrently with the Landlord’s construction of the Second Floor Tenant Improvements (as defined in Section 1.6(b) of the Fifth Amendment) and after Landlord’s construction of the Suite 310 Tenant Improvements (as defined in Section 1.6(b) of the Fifth Amendment).

(d) Intentionally Omitted.

(e) Intentionally Omitted.

(f) The parties