[Signature page to follow]

Akcea’s Right to Participate in the Funding of Development of the Product. At any time beginning on the Closing Date until  [***], Akcea will have the conditional right to elect to participate in the funding of the Development of the Product with Pfizer under the Development Plan pursuant to this Section 2.3.4. If Akcea provides written notice of such election to Pfizer prior to [***] (a “Notice of Interest”), then the Parties will negotiate in good faith the terms and conditions of Akcea’s participation in the funding of the Development of the Product with Pfizer under the Development Plan for a period of [***], including certain [***] terms for [***]. If Akcea (a) gives notice that it does not wish to participate in the funding of the Development of the Product with Pfizer under the Development Plan, (b) fails to give a timely Notice of Interest, or (c) gives a timely Notice of Interest but the Parties cannot mutually agree on the terms upon which Akcea will participate in the funding of the Development of the Product with Pfizer under the Development Plan by the [***] following the delivery of such notice, then (i) Akcea’s right to participate in the funding of the Development of the Product with Pfizer under the Development Plan pursuant to this Section 2.3.4 will automatically terminate, and (ii) Pfizer will continue to be solely responsible for the Development of the Product, including all funding, in accordance with the Development Plan.