Exhibit 10.1

FIFTH AMENDMENT TO LEASE

THIS FIFTH AMENDMENT TO LEASE (this “Fifth Amendment”) is made as of
September 4, 2014, by and between ARE-480 ARSENAL STREET, LLC, a Delaware
limited liability company (“Landlord”), and TETRAPHASE PHARMACEUTICALS, INC., a
Delaware corporation (“Tenant”).

RECITALS

A. Landlord and Tenant are parties to that certain Lease Agreement dated as of
November 16, 2006, as amended by that certain First Amendment to Lease dated as
of September 9, 2011, as further amended by that certain Second Amendment to
Lease dated as of March 15, 2012, as further amended by that certain Third
Amendment to Lease dated as of September 18, 2012, and as further amended by
that certain Fourth Amendment to Lease dated as of November 20, 2013 (as
amended, the “Lease”). Pursuant to the Lease, Tenant leases certain premises
consisting of approximately 15,899 rentable square feet (“Premises”) in a
building located at 480 Arsenal Street, Watertown, Massachusetts (“Building”).
The Premises are more particularly described in the Lease. Capitalized terms
used herein without definition shall have the meanings defined for such terms in
the Lease.

B. The Base Term of the Lease is currently scheduled to expire on July 31, 2015.

C. Landlord and Tenant desire to, among other things, amend the Lease to extend
the Term of the Lease through November 30, 2016.

NOW, THEREFORE, in consideration of the foregoing Recitals, which are
incorporated herein by this reference, the mutual promises and conditions
contained herein, and for other good and valuable consideration, the receipt and
sufficiency of which are hereby acknowledged, Landlord and Tenant hereby agree
as follows:

 

1. Base Term. The Base Term of the Lease is hereby extended to expire on
November 30, 2016.

 

2. Rent.

 

  a. Tenant shall continue paying Base Rent as provided in the Lease through
May 31, 2016. Commencing on June 1, 2016, Tenant shall pay Base Rent in the
amount of $57,910.87 per month through November 30, 2016.

 

  b. Tenant shall continue to pay Tenant’s Share of Operating Expenses and all
other charges as set forth in the Lease.

 

3. Miscellaneous.

 

  a. This Fifth Amendment is the entire agreement between the parties with
respect to the subject matter hereof and supersedes all prior and
contemporaneous oral and written agreements and discussions. This Fifth
Amendment may be amended only by an agreement in writing, signed by the parties
hereto.

 

  b. Landlord and Tenant each represents and warrants that it has not dealt with
any broker, agent or other person (collectively, “Broker”) in connection with
the transaction reflected in this Fifth Amendment and that no Broker brought
about this transaction. Landlord and Tenant each hereby agree to indemnify and
hold the other harmless from and against any claims by any Broker claiming a
commission or other form of compensation by virtue of having dealt with Tenant
or Landlord, as applicable, with regard to this leasing transaction.

 

LOGO [g794171g64z30.jpg]

 

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  c. This Fifth Amendment is binding upon and shall inure to the benefit of the
parties hereto, and their respective successors and assigns.

 

  d. This Fifth Amendment may be executed in any number of counterparts, each of
which shall be deemed an original, but all of which when taken together shall
constitute one and the same instrument. The signature page of any counterpart
may be detached therefrom without impairing the legal effect of the signature(s)
thereon provided such signature page is attached to any other counterpart
identical thereto except having additional signature pages executed by other
parties to this Fifth Amendment attached thereto.

 

  e. Except as amended and/or modified by this Fifth Amendment, the Lease is
hereby ratified and confirmed and all other terms of the Lease shall remain in
full force and effect, unaltered and unchanged by this Fifth Amendment. In the
event of any conflict between the provisions of this Fifth Amendment and the
provisions of the Lease, the provisions of this Fifth Amendment shall prevail.
Whether or not specifically amended by this Fifth Amendment, all of the terms
and provisions of the Lease are hereby amended to the extent necessary to give
effect to the purpose and intent of this Fifth Amendment.

[Signatures are on the next page.]

 

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IN WITNESS WHEREOF, parties hereto have executed this Fifth Amendment as of the
day the and year first above written.

 

LANDLORD:    

ARE-48O ARSENAL STREET, LLC,

a Delaware limited liability company

   

By:   ALEXANDRIA REAL ESTATE EQUITIES, L.P.,
a Delaware limited partnership,
managing member

   

By:   

  LOGO [g794171g87f19.jpg] TENANT:     LOGO [g794171g90r61.jpg]            

 

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