EX-4.3



 Exhibit 4.3 

AMENDMENT NO. 1 TO 
 THE
THIRD AMENDED AND RESTATED VOTING AGREEMENT 
 THIS AMENDMENT NO. 1 TO THE THIRD AMENDED AND RESTATED VOTING AGREEMENT (this
“Amendment”) is made and effective as of May 31, 2013, by and among Akebia Therapeutics, Inc., a Delaware corporation (the “Company”), and the “Stockholders” as defined in that certain Third Amended
and Restated Voting Agreement, dated as of May 10, 2013, by and among the Company and the Stockholders a party thereto (the “Agreement”). Capitalized terms not defined herein have the meanings given them in the Agreement.

 RECITALS 

WHEREAS, on May 10, 2013, the Agreement was entered into by the Company and the Investors in connection with the transactions and
agreements contemplated in that certain Series C Preferred Stock Purchase Agreement by and between the Company and certain parties as listed therein, dated as of May 10, 2013 (the “Series C Stock Purchase Agreement” and the
transactions and agreements contemplated therein collectively the “Series C Transaction”); and 
 WHEREAS, in
connection with an Additional Closing (as defined in the Series C Stock Purchase Agreement) to the Series C Transaction dated May 31, 2013, the Company and the Stockholders holding more than the Appropriate Percentage (as defined in the
Agreement) of the shares of the Company’s Common Stock issuable upon conversion of the outstanding shares of the Company’s Preferred Stock (as defined in the Agreement) desire to amend the Agreement in accordance with the terms and
conditions more fully set forth in this Amendment. 
 NOW, THEREFORE, in consideration of the foregoing premises and the
mutual covenants hereinafter set forth, and other good and valuable consideration had and received, the parties hereto, upon the terms and subject to the conditions contained herein, hereby agree as follows: 

1. Amendments. 
 (a) Section 1.2(d)
is hereby amended by deleting it in its entirety and replacing it with the following: “(d) As Preferred Directors, two persons designated by Novo A/S (each, a “New Investor Director”).” 

(b) Section 6.8(i) is hereby amended by deleting it in its entirety and replacing it with the following: 

(i) this Agreement may not be amended or terminated and the observance of any term of this Agreement may not be waived with respect to any
Stockholder without the written consent of such Stockholder unless such amendment, termination or waiver applies to all Stockholders in the same fashion, and provided that (the following provisions of this Section 6.8(i) proviso, the
“Liability Proviso”) any amendment of Sections 3.3(c) and 3.3(d) hereof, as well as any amendment of this Liability Proviso, shall require, in addition to any other approvals required by this Section 6.8, also the approval of
(A) Satter Investment 

  
 1 








 
Management, LLC so long as Satter Investment Management, LLC or any of its Affiliates holds any Preferred Stock or Common Stock issued upon conversion of any of such Preferred Stock,
(B) Novartis Bioventures Ltd. so long as Novartis Bioventures Ltd. holds any Preferred Stock or Common Stock issued upon conversion of any of such Preferred Stock, and (C) Novo A/S so long as Novo A/S holds any Preferred Stock or Common
Stock issued upon conversion of any of such Preferred Stock; 
 (c) Section 6.8 (iv) is hereby amended by deleting it in its
entirety and replacing it with the following: 
 (iv) Section 1.2(a) of this Agreement shall not be amended or waived without the
written consent of Satter Investment Management, LLC, Section 1.2(b) of this Agreement shall not be amended or waived without the written consent of Novartis Bioventures Ltd., Section 1.2(c) shall not be amended or waived without the
written consent of Kearny Venture Partners, Section 1.2(d) shall not be amended or waived without the written consent of Novo A/S, Section 1.2(e) shall not be amended or waived without the written consent of the holders of a majority of
the outstanding shares of Common Stock (including, on an as-converted to Common Stock basis, all shares of Preferred Stock convertible into Common Stock) and Section 1.6 shall not be amended or waived without the written consent of Satter
Investment Management, LLC and Novartis Bioventures Ltd. Notwithstanding the foregoing, if any amendment, modification, termination or waiver of this section or any other section or subsection of this Agreement would deprive Satter Investment
Management, LLC, Novartis Bioventures Ltd., Kearny Venture Partners, or Novo A/S of its director designation rights (or of Duane Nash’s right to be named to the Board) under Section 1.2, then the written consent of such party or such
person (in the case of Mr. Nash) shall be required. 
 2. Miscellaneous Amendments. The Agreement is amended hereby so that any
reference therein to the Agreement shall be deemed to be a reference to the Agreement as amended by this Amendment. 
 3. Continuance of
Agreement. Except as specifically amended by this Amendment, the Agreement shall remain in full force and effect. 
 4. Governing
Law. The laws of the State of Delaware govern all matters arising out of or relating to this Amendment, including, without limitation, its interpretation, construction, performance, and enforcement, without giving effect to such state’s
conflicts of law principles or rules of construction concerning the drafter hereof. 
 5. Counterparts. This Amendment may be
executed in two or more counterparts, including by facsimile or PDF signature, each of which shall be deemed an original, but all of which together shall constitute one and the same instrument. 

[Signature Page Follows] 

  
 2 








 IN WITNESS WHEREOF, the parties hereto have caused this Amendment to be executed as of the date
first written above. 
  

			
	AKEBIA THERAPEUTICS, INC.
		
	By:	 	 /s/ Joseph H. Gardner

		 	 Joseph H. Gardner, Ph.D.
 President and Chief
Executive Officer

	
	Address:
	
	 9987 Carver Road, Suite 420

Cincinnati, OH 45242




  
 SIGNATURE PAGE TO
AMENDMENT NO. 1 TO 
 THE THIRD AMENDED AND RESTATED VOTING AGREEMENT 








 IN WITNESS WHEREOF, the parties hereto have caused this Amendment to be executed as of the date
first written above. 
  

			
	NOVARTIS BIOVENTURES LTD.
		
	By:	 	 /s/ Simon Zivi

		 	Name: Simon Zivi
		 	Title: Deputy Chairman
		
	By:	 	 /s/ Rebecca White

		 	Name: Rebecca White
		 	Title: Authorized Signatory
	
	Address:
	
	 NOVARTIS BIOVENTURES LTD.
 Attn:
Henri Simon Zivi
 131 Front Street
 Hamilton HM 12

Bermuda
  

But for mail, to: 
  

Novartis BioVentures Ltd.
 Attn: Henri Simon Zivi

PO Box HM 2899
 Hamilton HM LX Bermuda

 
 And, also send a copy to: 

 
 Novartis Venture Fund

Attn: Campbell Murray
 Five Cambridge Center, Suite 603

Cambridge, MA 02142
  




  
 SIGNATURE PAGE TO
AMENDMENT NO. 1 TO 
 THE THIRD AMENDED AND RESTATED VOTING AGREEMENT 








 IN WITNESS WHEREOF, the parties hereto have caused this Amendment to be executed as of the date
first written above. 
  

			
	VENTURE INVESTORS EARLY STAGE FUND IV LIMITED PARTNERSHIP
		
	By:	 	VIESF IV GP, LLC, its General Partner
		
	By:	 	 /s/ Paul M. Weiss

		 	 Name: Paul M. Weiss, PhD
 Title: Managing
Director

	
	Address:
	
	 505 South Rosa Road
 Madison, WI
53719-1262
 Attn: Paul Weiss, Managing Director
 Phone:
(608) 441-2700
 Fax: (608) 441-2727
 Email:
paul@ventureinvestors.com




  
 SIGNATURE PAGE TO
AMENDMENT NO. 1 TO 
 THE THIRD AMENDED AND RESTATED VOTING AGREEMENT 








 IN WITNESS WHEREOF, the parties hereto have caused this Amendment to be executed as of the date
first written above. 
  

			
	TRIATHLON MEDICAL VENTURES FUND, L.P.
		
	By:	 	Triathlon Medical Ventures, LLC
	Its:	 	General Partner
		
	By:	 	 /s/ John M. Rice

		 	 John M. Rice
 Managing Partner

	
	 Address:
  

300 E-Business Way
 Suite 200

Cincinnati, OH 45241




  
 SIGNATURE PAGE TO
AMENDMENT NO. 1 TO 
 THE THIRD AMENDED AND RESTATED VOTING AGREEMENT 








 IN WITNESS WHEREOF, the parties hereto have caused this Amendment to be executed as of the date
first written above. 
  

			
	KEARNY VENTURE PARTNERS, L.P.
		
	By:	 	/s/ Anupam Dalal
	Name: Kearny Venture Associates, LLC
	Title: its General Partner
	  
 Address:

 
 Attn: Anupam Dalal

Kearny Venture Associates LLC
 88 Kearny Street, Suite 1800

San Francisco, CA 94108-5530
  

KEARNY VENTURE PARTNERS ENTREPRENEURS FUND, L.P.

		
	By:	 	/s/ Anupam Dalal
	 Name: Kearny Venture Associates, LLC

Title: its General Partner

	  
 Address:

 
 Attn: Anupam Dalal

Kearny Venture Associates LLC
 88 Kearny Street, Suite 1800

San Francisco, CA 94108-5530




  
 SIGNATURE PAGE TO
AMENDMENT NO. 1 TO 
 THE THIRD AMENDED AND RESTATED VOTING AGREEMENT 








 IN WITNESS WHEREOF, the parties hereto have caused this Amendment to be executed as of the date
first written above. 
  

			
	THOMAS WEISEL HEALTHCARE VENTURE PARTNERS, L.P.
	
	 By:    Thomas Weisel Capital Management LLC

Title:  its Managing Member

		
	By:	 	 /s/ Anupam Dalal

	 Name: Anupam Dalal
 Title: Managing
Director
  
 Address:

 
 88 Kearny Street, Suite 1800

San Francisco, CA 94108




  
 SIGNATURE PAGE TO
AMENDMENT NO. 1 TO 
 THE THIRD AMENDED AND RESTATED VOTING AGREEMENT 








 IN WITNESS WHEREOF, the parties hereto have caused this Amendment to be executed as of the date
first written above. 
  

			
	ATHENIAN VENTURE PARTNERS III L.P.
	
	 By:    Athenian III, Ltd

Its:    General Partner

		
	By:	 	 /s/ Karl O. Elderkin

	 Name: Karl O. Elderkin
 Title:
President

	
	AVP OHIO TECHNOLOGY I L.P.
	
	 By:    AVP Ohio I, Ltd.

Its:    General Partner

		
	By:	 	 /s/ Karl O. Elderkin

	 Name: Karl O. Elderkin
 Title:
President
  
 Address:

 
 340 West State Street

Unit 29/Suite 137D
 Athens OH 45701




  
 SIGNATURE PAGE TO
AMENDMENT NO. 1 TO 
 THE THIRD AMENDED AND RESTATED VOTING AGREEMENT 








 IN WITNESS WHEREOF, the parties hereto have caused this Amendment to be executed as of the date
first written above, 
  

			
	AGECHEM VENTURE FUND L.P.
		
	By:	 	/s/ Louis Lacasse
	 Name: Louis Lacasse
 Title:
President
  
 Address:

 
 Attn: Louis Lacasse, President

1 Westmount Square, Suite 800
 Montreal, Quebec, Canada

H3Z 2P9




  
 SIGNATURE PAGE TO
AMENDMENT NO. 1 TO 
 THE THIRD AMENDED AND RESTATED VOTING AGREEMENT 








 IN WITNESS WHEREOF, the parties hereto have caused this Amendment to be executed as of the date
first written above. 
  

			
	 CINCINNATI CORNERSTONE INVESTORS

AKB, LLC

		
	By:	 	/s/ Robert W. Coy, Jr.
		 	    Robert W. Coy
		 	    President
		 	
	Address:
	
	 30 West 3rd Street, 6th
Floor
 Cincinnati, OH 45202-3559




  
 SIGNATURE PAGE TO
AMENDMENT NO. 1 TO 
 THE THIRD AMENDED AND RESTATED VOTING AGREEMENT 








 IN WITNESS WHEREOF, the parties hereto have caused this Amendment to be executed as of the date
first written above. 
  

			
	FAMILY AKEBIA INVESTMENTS LLC
		
	By:	 	/s/ Milton Berlinski
	Name: Milton Berlinski
	Title:   Managing Member
		 	
	Address:
	
	 1185 Park Avenue #11G
 New York, NY
10128




  
 SIGNATURE PAGE TO
AMENDMENT NO. 1 TO 
 THE THIRD AMENDED AND RESTATED VOTING AGREEMENT 








 IN WITNESS WHEREOF, the parties hereto have caused this Amendment to be executed as of the date
first written above. 
  

			
	MUNEER A. SATTER REVOCABLE TRUST
		
	By:	 	/s/ Muneer A. Satter
	Name: Muneer A. Satter
	Title:   Trustee


  

			
	THE SATTER FOUNDATION
		
	By:	 	/s/ Muneer A. Satter
	Name: Muneer A. Satter
	Title:   Trustee


  

			
	SATTER FAMILY TRUST
		
	By:	 	/s/ Muneer A. Satter
	Name: Muneer A. Satter
	Title:   Investment Advisor


  

			
	SATTER CHILDREN’S TRUST I
		
	By:	 	/s/ Muneer A. Satter
	Name: Muneer A. Satter
	Title:   Investment Advisor
	
	Address:
	
	 c/o Satter Investment Management, LLC

676 N. Michigan Avenue, Suite 4000
 Chicago, IL 60611

Attn: Muneer A. Satter




  
 SIGNATURE PAGE TO
AMENDMENT NO. 1 TO 
 THE THIRD AMENDED AND RESTATED VOTING AGREEMENT 








 IN WITNESS WHEREOF, the parties hereto have caused this Amendment to be executed as of the date
first written above. 
  

			
	KRISTEN HAYLER HERTEL REVOCABLE TRUST
		
	By:	 	/s/ Kristen Hayler Hertel
	Name: Kristen Hayler Hertel
	 Title:    Trustee
  

	
	Address:
	
	c/o Satter Investment Management, LLC 676 N. Michigan Avenue, Suite 4000 Chicago, IL 60611 Attn: Muncer A. Satter



  
 SIGNATURE PAGE TO
AMENDMENT NO. 1 TO 
 THE THIRD AMENDED AND RESTATED VOTING AGREEMENT 








 IN WITNESS WHEREOF, the parties hereto have caused this Amendment to be executed as of the date
first written above. 
  

			
	ANNE-CAROLE WITORT INSURANCE TRUST
		
	By:	 	/s/ Muneer A. Satter
	 Name: Muneer A. Satter
 Title:
Trustee

	
	ROSE SHEREEN FUQUA INSURANCE TRUST
		
	By:	 	/s/ Muneer A. Satter
	 Name: Muneer A. Satter
 Title:
Investment Advisor

	
	RABI H. SATTER INSURANCE TRUST
		
	By:	 	/s/ Muneer A. Satter
	 Name: Muneer A. Satter
 Title:
Investment Advisor

	
	JOHN WOOD TRUST
		
	By:	 	/s/ Muneer A. Satter
	 Name: Muneer A. Satter
 Title:
Investment Advisor
  
 Address:

 
 c/o Satter Investment Management, LLC

676 N. Michigan Avenue, Suite 4000
 Chicago, IL 60611

Attn: Muneer A. Satter




  
 SIGNATURE PAGE TO
AMENDMENT NO. 1 TO 
 THE THIRD AMENDED AND RESTATED VOTING AGREEMENT 








 IN WITNESS WHEREOF, the parties hereto have caused this Amendment to he executed as of the date
first written above. 
  

			
	ABDUS SATTER INSURANCE TRUST
		
	By:	 	/s/ Muneer A. Satter
	 Name: Muneer A. Satter
 Title:
Trustee

	
	GORDON AND BARBARA ANNE HERTEL INSURANCE TRUST
		
	By:	 	/s/ Muneer A. Satter
	 Name: Muneer A. Satter
 Title:
Trustee
  
 Address:

 
 c/o Satter Investment Management, LLC

676 N. Michigan Avenue, Suite 4000
 Chicago, IL 60611

Attn: Muneer A. Satter




  
 SIGNATURE PAGE TO
AMENDMENT NO. 1 TO 
 THE THIRD AMENDED AND RESTATED VOTING AGREEMENT