Prosensa actively working on re-dosing drisapersen and regulatory path forward

CureDuchenne is pleased to share the following information from Prosensa.

Dear Patient Group Representative,

As we continue to receive all of the materials, data and know-how from GSK regarding the drisapersen clinical data set, we continue to actively work on re-dosing and engage with regulators to determine a path forward for drisapersen. We remain on track to re-dosing the first cohort of boys in the 3rd quarter of this year and to communicating around a regulatory path forward for drisapersen before the end of June.

As communicated during the UPPMD webinar on March 25th, re-dosing will likely take a staged approach, under a new treatment protocol or via an expanded access program, which is often country dependent. In a first wave, we plan to initiate dosing at sites in both North America and Europe and we have already started to work with the sites and investigators to execute these plans. As these plans have not yet finalized, we cannot provide more detail at this particular time. We realize that this is a very difficult period for the boys and families and we are working as quickly as possible to provide access to drisapersen and determine a path forward. As soon as we have concrete information on re-dosing we will communicate our plans in a timely manner. For your information, the recent webinar is accessible at http://ir.prosensa.eu/events.cfm (under additional information on the event). Prosensa will also provide an update on drisapersen during the American Academy of Neurology (AAN) 2014 Annual Meeting on April 30th and will continue to finalize the transfer of all data and materials from GSK over the next few weeks.

We have been following the recent communication in the DMD community and are encouraged that there seems to be a certain regulatory flexibility with respect to potential pathways for investigational products for the treatment of DMD. Prosensa is in contact with regulators in both Europe and the US with the aim to obtain their input into the regulatory path forward for drisapersen and we expect to communicate on this before the end of June. We feel positive about the FDA’s commitment to DMD and their willingness to work closely with all key stakeholders and consider flexible approaches to expedite the availability of treatment options for DMD. Prosensa is dedicated to do what it takes to enable long term access to drisapersen and our follow-on products as novel treatments for DMD. We are determined to accomplish this as soon as possible.

We will keep you informed on all of the above. Please do not hesitate to contact us for questions!

With kind regards,

Giles Campion, MD —Chief Medical Officer and SVP Research & Development

Claire Leyten, PharmD — Manager Patient Group Relations and primary point of contact for enquiries from patients and their families (patientinfo@prosensa.nl)