EXHIBIT 4.4











THE SYMBOL "[****]"
DENOTES PLACES WHERE PORTIONS OF THIS DOCUMENT HAVE BEEN OMITTED PURSUANT TO A REQUEST FOR CONFIDENTIAL TREATMENT. SUCH MATERIAL
HAS BEEN FILED SEPARATELY WITH THE SECURITIES AND EXCHANGE COMMISSION.



Montreal, January 31st 2013



Ori Shilo

Deputy CEO, Finance and Operations

RedHill Biopharma Ltd.

21 Ha'arba'a St.

Tel-Aviv

64739

Israel



Re: Side Letter Agreement with RedHill
Biopharma Ltd.



Dear Mr. Shilo,



RedHill Biopharma Ltd. (“RedHill”)
and IntelGenx Corp. (“IntelGenx”) have entered into that certain Co-Development and Commercialization Agreement (the
“Agreement”), dated as of August 26th, 2010, in respect of the development of an oral film containing rizatriptan
(“Product”). IntelGenx is the current sole and legal owner of New Drug Application #205394 (“NDA”) and
Investigational New Drug #110753 (“IND”), both pertaining to the Product. RedHill and IntelGenx (collectively,
the “Parties”) hereby enter into this Side Letter Agreement to define the Parties’ respective roles and responsibilities
associated with the transfer and ownership of NDA #205394 and IND #110753 in respect of the Product.



| | 1) | Ownership and Regulatory filing. In accordance with section 4.3 of the Agreement, RedHill
will become financially responsible for the payment of the Prescription Drug User Fee Act (“PDUFA”) fee. At its sole
discretion, RedHill will either pay the PDUFA fee or seek to obtain a small business fee waiver as defined under 736(d)(1)(E) of
the FD&C Act by the FDA. Since RedHill has decided to be financially responsible for the PDUFA fee, IntelGenx shall transfer
the NDA and the IND for the Product to RedHill to enable Redhill, in accordance with section 4.9 of the Agreement, to file the
NDA application with the FDA and act as the applicant during the regulatory process.
| | -- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------















In accordance with section
4.9 of the Agreement, the joint ownership of the NDA by the Parties remains unchanged by the transfer of the NDA. Any decisions
regarding the preparation and prosecution of the NDA will be made by the Steering Committee as provided in section 4.9 of the Agreement.
For the avoidance of doubt, the responsibilities of the parties as per section 5 of the Agreement remain unchanged by the transfer
of the NDA.



| | 2) | Expenses For Completion Of Project. In addition to those costs and expenses at RedHill’s
charge identified in the R&D Budget (as defined in the Agreement), RedHill agrees to pay the expenses and costs specified in
Exhibit A, in excess of the agreed budget.
| | -- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------



| | 3) | Data Transfer.RedHill shall provide IntelGenx with a complete copy of all regulatory filings
made by RedHill and all communications, relating to the Product, with the FDA. RedHill shall not make changes to the NDA for the
Product, which would change the NDA in any form or way without prior written approval by IntelGenx. RedHill shall reasonably provide
to IntelGenx upon reasonable request, at no cost to IntelGenx, copies of all the pertinent information it has about the Product
including, but not limited to, the entire NDA file, Regulatory Activities, communications with Regulatory Authorities in the US,
Regulatory Documentation, manufacturing, supply, external service and other contracts and any and all other information whatsoever
that is relevant for the development, marketing approval, marketing and other commercialization of the Product. For the sake of
clarity, the responsibility of IntelGenx for all regulatory aspects of the Product remains intact as per the Agreement.
| | -- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------



| | 4) | NDA Transfer To Commercial Partner. The Parties agree that, upon execution of a commercialization
and licensing agreement for the Product with a commercial partner that includes the transfer of the NDA to the partner, the Parties
will transfer full NDA and IND ownership to the commercial partner on terms to be agreed at the time of entering into the agreement
with the commercial partner.
| | -- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------



| | 5) | Notification to FDA. Within ten (10) calendar days after the execution of this Side Letter
Agreement, the Parties shall execute and deliver to the FDA any and all documents necessary in order to identify RedHill as applicant
for the NDA of the Product.
| | -- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------



Page 2 of 5











| | 6) | Assistance. Both Parties agree that they should provide reasonable assistance to each other
for the preparation and filing of the NDA associated with the Product.
| | -- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------



Article 17.3 of the Agreement applies to
this Side Letter Agreement.



Unless specifically provided in this Side
Letter Agreement, the terms of the Agreement shall continue to apply.



This Side Letter Agreement may be executed
in one or more counterparts, each of which shall be deemed an original but taken together shall constitute one and the same agreement.
It may be executed by facsimile, which shall be deemed an original for all purposes.



To confirm your agreement with the terms
of this Side Letter Agreement, please sign the acknowledgement below and return it to the address listed below.



Sincerely,



|IntelGenx Corp.            |                    | RedHill Biopharma Ltd.            
|-------------------------- | ------------------ | ----------------------------------
|                           |                    |                                   
|By:                        | /s/Paul A. Simmons |                                   
|Paul A. Simmons            |                    | Ori Shilo                         
|CFO                        |                    | Deputy CEO, Finance and Operations
|Date: January 31st 2013    |                    | Date: January 31st 2013           
|                           |                    |                                   
|By:                        | /s/ Horst G. Zerbe |                                   
|Horst G. Zerbe, Ph.D., CEO |                    | Dror Ben-Asher, CEO               
|Date: January 31st 2013    |                    | Date: January 31st 2013           
|                           |                    |                                   
|6425 Abrams                |                    | 21 Ha'arba'a St.                  
|Ville St-Laurent (Qc)      |                    | Tel-Aviv                          
|H4S 1X9                    |                    | 64739                             
|Canada                     |                    | Israel                            



Page 3 of 5











Exhibit A – Additional R&D
expenses



Upon signing this Side Letter Agreement,
RedHill agrees to reimburse IntelGenx for additional R&D expenses that exceed the R&D budget as defined in the Agreement
upon the following conditions:

| | 1. | Such expenses are under the manufacturing agreement between IntelGenx and [****].
| | -- | ---------------------------------------------------------------------------------

| | 2. | Such expenses were actually accrued by [****] and were billed to IntelGenx.
| | -- | ---------------------------------------------------------------------------

| | 3. | Such expenses are in accordance with the hours proposed in the schedule entitled “Timeline
and cost estimate riza oct 25 2012.pdf” attached here to as Exhibit B.
| | -- | -----------------------------------------------------------------------------------------------------------------------------------------------------------------

| | 4. | Such expenses are only in accordance to the preparation of the NDA submission.
| | -- | ------------------------------------------------------------------------------

| | 5. | Such expenses are in accordance with the table below
| | -- | ----------------------------------------------------

| | 6. | Such expenses will not exceed the number of hours, the hourly rate and the maximum additional costs
as defined in the table below.
| | -- | ----------------------------------------------------------------------------------------------------------------------------------



|task                                      |  | Max. Number of hours |  |  | Hourly Rate |  |  | Max. additional costs |  |  | Comments | 
|----------------------------------------- |  | -------------------- |  |  | ----------- |  |  | --------------------- |  |  | -------- | 
|[****]                                    |  | [****]               |  |  | EUR [****]  |  |  | EUR [****]            |  |  |          | 
|Regulatory Support and project management |  | [****]               |  |  | EUR [****]  |  |  | EUR [****]            |  |  |          | 
|Total                                     |  | [****]               |  |  | EUR [****]  |  |  | EUR [****]            |  |  |          | 
|                                          |  |                      |  |  |             |  |  |                       |  |  |          | 



|IntelGenx Corp.         |                     | RedHill Biopharma Ltd.            
|----------------------- | ------------------- | ----------------------------------
|                        |                     |                                   
|By:                     | /s/ Paul A. Simmons |                                   
|Paul A. Simmons         |                     | Ori Shilo                         
|CFO                     |                     | Deputy CEO, Finance and Operations
|Date: January 31st 2013 |                     | Date: January 31st 2013           
|                        |                     |                                   
|                        |                     |                                   
|                        |                     |                                   
|                        |                     |                                   



Page 4 of 5











Exhibit B – Development plan



[****]



Page 5 of 5