The Parties [***] as set forth in the attached GSK-5 Development Plan.
Isis will be responsible for, and will use Commercially Reasonable Efforts to perform, Isis' activities under the GSK-5 Development Plan and will be responsible for all costs and expenses associated therewith, except to the extent such costs and expenses have otherwise been allocated to GSK under Section 1, Section 3.c or Section 5 of this Amendment No. 4.
Isis will consider in good faith any changes to the GSK-5 Development Plan that are requested by GSK that do not require the Parties to make a Material Amendment to the GSK-5 Development Plan to affect such a change.
The initial agreed-upon GSK-5 Development Plan is attached to this Amendment No. 4 as Attachment 1.
Until GSK exercises its Option for the GSK-5 Program in accordance with the Agreement (as amended by this Amendment No. 4), GSK will be responsible for and will use Commercially Reasonable Efforts to perform the activities allocated to GSK under the GSK-5 Development Plan, and shall be responsible for payment of all costs and expenses related to GSK's conduct of such activities.