Exhibit 24

                               POWER OF ATTORNEY

The undersigned hereby makes, constitutes and appoints AstraZeneca PLC as its
true and lawful attorney-in-fact and agent, with full power of substitution and
re-substitution for it and in its name, place and stead, in any and all
capacities, to execute and deliver any Schedule 13G, Schedule 13D, Forms 3, 4 or
5, or any amendments, restatements, supplements, and/or exhibits thereto,
required to be filed with the U.S. Securities and Exchange Commission under the
Securities Exchange Act of 1934, as amended, on behalf of the undersigned with
regard to any securities owned by the undersigned; and, in connection with the
foregoing, to execute and deliver all documents, acknowledgements, consents and
other agreements and to take such further action as may be necessary or
convenient in order to more effectively carry out the intent and purpose of the
foregoing.

Dated: October 12, 2012

                                        ASTRAZENECA AB

                                        By:   /s/ Jan-Olof Jacke
                                           -------------------------------------
                                        Name: Jan-Olof Jacke
                                        Title: Authorized Signatory