Exhibit 4.23



Amendment 1.3 to Agreement dated 26thDec ’08 signed by and between



Dr. Reddy’s Laboratories Limited

Bollaram Road, Miyapur,

Hyderabad 500 049

India

(Hereinafter referred to as “Dr. Reddy’s”)



And



Prana Biotechnology Ltd

Level 2, 369 Royal Parade, Parkville Victoria,
3052

Australia

(Hereinafter referred to as “Prana”)



Dr. Reddy’s and Prana are collectively
referred to as the “PARTIES”





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This amendment will include the following additional and amended
clauses in the above mentioned Agreement (plus amendments) and will be in effect from 14 February 2012 onwards.



|1. | Terms to be included                                           
|-- | ---------------------------------------------------------------
|i. | The following new clause-12 in Appendix
    A of the Agreement:



“12. Sub-Project 4A: Qualification of Dr Reddy’s
Reference Standard in comparison with IDT Reference Standard

| | a) | Dr. Reddy’s will analyse the Dr Reddy’s Reference Standard (CDDQ5RS1101) and the IDT Reference Standard (DA102301.1) side-by-side using Dr Reddy’s methods.            
| | -- | -----------------------------------------------------------------------------------------------------------------------------------------------------------------------
| | b) | This will include:                                                                                                                                                     
| |    | i.                                                                                                                                                                     
| |    | ii.                                                                                                                                                                    
| |    | iii.                                                                                                                                                                   
| |    | iv.                                                                                                                                                                    
| |    | v.                                                                                                                                                                     
| |    | vi.                                                                                                                                                                    
| |    | vii.                                                                                                                                                                   
| |    | viii.                                                                                                                                                                  
| |    | ix.                                                                                                                                                                    
| | c) | Related Substances analysis to be performed in one sequence. Same tests to be performed on same day or in same sequence for reference standards of Dr. Reddy’s and IDT.



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| | d) | Report containing all raw data and comments on comparability of the two Reference Standards to be provided. This should be an addendum to the existing Reference Standard report titled “Report on PBT2 reference standard preparation (I-CDDQ-10-0318)”.
| | -- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------



|ii.  | The following description of new Sub-Project 4A under Sub-Project Pricing in clause 3 of the Agreement                  
|---- | ------------------------------------------------------------------------------------------------------------------------
|     |                                                                                                                         
|     | “Sub-Project 4A: Qualification of Dr Reddy’s Reference Standard in comparison with IDT Reference Standard – USD 4,000/-”
|     |                                                                                                                         
|iii. | The following description of new Sub-Project payment terms in clause 3 of the Agreement                                 
|     |                                                                                                                         
|     | “Sub-Project 4A:                                                                                                        
|     |                                                                                                                         
|     | ●                                                                                                                       
|     |                                                                                                                         
|2.   | Terms to be varied                                                                                                      
|i.   | The current numbering of the following clause heading in Appendix A of the Agreement, as amended in Amendment 10:       



“12. Sub-Project 6: Stability Study (48 months)”



is amended as follows



“13. Sub-Project 6: Stability Study (48 months)”



All other terms and conditions of the original
Agreement dated 26th Dec’08 and those included in Amendments 1 to 12 remain unchanged.



In witness whereof, the parties hereto have signed this Agreement



|Signed for and on behalf of      |  | Signed for and on behalf of    
|-------------------------------- |  | -------------------------------
|Dr. Reddy’s Laboratories Limited |  | Prana Biotechnology Ltd.       
|                                 |  |                                
|                                 |  |                                
|Signature                        |  | Signature                      
|Name: Manoj Mehrotra             |  | Name: Dianne Angus             
|                                 |  |                                
|                                 |  |                                
|Witness Signature                |  | Witness Signature              
|Witness Name: Vikas Tripathi     |  | Witness Name: Elisabeth Gautier





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