Greetings and welcome to the Prosensa Holding N.V. Third Quarter 2013 Earnings Conference Call. At this time, all participants are in a listen-only mode. A brief question-and-answer session will follow the formal presentation. (Operator Instructions) As a reminder, this conference is being recorded. I'll now turn the conference over to Celia Economides, Director of Investor Relations and Corporate Communications at Prosensa. Thank you, Ms. Economides. You may begin.

Thank you, operator, and thank you for joining us. On behalf of Prosensa, I would like to welcome everyone to our third quarter earnings call which ended on September 30, 2013. With me today are Hans Schikan, Chief Executive Officer, Berndt Modig, Chief Financial Officer, and joining us for the Q&A are Giles Campion, Chief Medical Officer, and Luc Dochez, Chief Business Officer. Earlier today, we issued a press release containing results for the third quarter of 2013 which is available on our website at Prosensa.com. We will also file our full third quarter interim financial statements and management discussion and analysis with the SEC. During today's call, we may make forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. These include statements about our future expectations, clinical developments and regulatory timelines, the potential success of our product candidates and financial projections. Actual results may differ materially from those indicated by these statements. Forward-looking statements during this call include statements around our exon skipping drug pipeline, our financial position, and our collaboration with GSK. Such forward-looking information involves risks and uncertainties that could significantly affect expected results. These risks and uncertainties are discussed in the Company’s SEC filings including, but not limited to, the Company’s Form 6-K containing the Q3 press release and certain sections of the Company’s registration statement on Form F-1. In addition, any forward-looking statements represent our views only as of today and should not be relied upon as representing our views as of any subsequent date. While we may elect to update these forward-looking statements at some point in the future, we specifically disclaim any obligation to do so even if our views change. With that, let me pass the call over to Hans.

Thank you, Celia, and good morning and good afternoon everyone. As Celia stated, this is our second quarterly earnings call as a newly public company. As we close out the year, we would like to provide you with an update on our current portfolio, where we stand with our lead exon skipping compound drisapersen, and provide an update on our financials. Our third quarter was marked by a number of scientific presentations and by the release of the Phase III results of drisapersen with our collaboration partner GSK who obtained an exclusive and worldwide license to develop and commercialize drisapersen from Prosensa. On the 20th of September, together with GSK, we announced that the Phase III clinical study, DMD114044 or also called DEMAND III of drisapersen, an investigational antisense oligonucleotide for the treatment of duchenne muscular dystrophy with an amenable mutation, did not meet the primary endpoint of a statistically significant improvement in the 6-minute walking distance test compared to placebo. These results were disappointing in view of encouraging results in three separate earlier studies. The first one concerns a long-term open-label study, DMD114673, where data have been generated for almost four years, and two exploratory placebo-controlled studies of which DMD114117 or DEMAND II shows the clinically meaningful and statistically significant outcome on the primary endpoint, the 6-minute walk test, after 25 weeks of treatment. The treatment effect was maintained after 49 weeks of treatment with p-value of 0.051. The other placebo-controlled study, DMD114876 or DEMAND V, shows a clinically meaningful though not statistically significant outcome. Together with GSK, we are working diligently to complete a full [inaudible] of drisapersen treatments across all these studies. GSK has indicated that these analyses should be complete by the end of the year. This allows also include analyses of pooled results from the various drisapersen studies. Needless to say, this news was also incredibly disappointing to the DMD patient community worldwide who are in great need for a treatment for this devastating disease. We want to confirm that we remain committed to drisapersen and the overall DMD program and will continue to work closely with GSK on the overall program and this additional data analysis. To-date, more than 300 patients have participated in the clinical studies of drisapersen globally and we are actively working with key patient groups, both in the U.S. and Europe, to provide them with as much information as possible as we learn more. As you are aware, DMD is one of the most prevalent rare genetic diseases globally affecting up to 1-in-3,500 boys and it's invariably fatal. There is currently no approved disease-modifying therapy for DMD. Thus, research and development of possible treatment options is of critical importance for boys and their families affected by DMD. This has driven us to develop a portfolio of products targeting DMD and continues to drive us to find treatment. We remain steadfast in our commitment to work closely with patient groups and to provide as much information about the drisapersen program as soon as possible. In recent months, Prosensa has had a number of presentations on our extensive DMD portfolio and the study of the natural history of the disease at key scientific and medical meetings, which further reinforces the depth and breadth of our R&D capabilities. On the 25th of September, at the DIA/FDA Oligonucleotide based Therapeutics Conference, Dr. Craig McDonald of UC Davis Children's Hospital presented for the first time data from DEMAND V study, DMD114876, a Phase II exploratory study to assess two doses of drisapersen in the treatment of ambulant boys with DMD. At the 6mg/kg/week dose, drisapersen showed a 27 meter benefit over placebo on the 6-minute walk test, which was clinically meaningful but not statistically significant. Summary results from this study, DEMAND V study, were also published on the GSK Clinical Study Register this past Friday. As we have previously reported, our investigational DMD portfolio includes six identified compounds, all of which have received orphan drug status in the United States and the European Union. Outside of drisapersen, we remain excited about the other compounds in our DMD portfolio and the progress we are making in the study on the natural history of the disease. Beyond drisapersen, we have five additional compounds that could address other existing sub-populations of DMD patients. We believe the results from the additional drisapersen data analysis will help inform our follow-on programs. While we anticipate these evaluations could enable more robust studies for our follow-on programs, it may affect the timing for these studies. On the 6th of September, we announced dosing of the first patient in our Phase 1/II clinical trial of PRO053, the Company's fourth compound in the clinic for DMD. PRO053 induces exon 53 skipping and may be applicable to approximately 8% of all DMD patients. This is an open-label study designed to assess the safety, efficacy, tolerability and pharmacokinetics of multiple doses of PRO053 in a subset of patients with DMD. The primary outcome measure of the study will be change from baseline in the six-minute walk test after 48 weeks of treatment. A number of secondary outcome measures will also be assessed, including safety, muscle function and strength, and functional outcome based on a questionnaire. The initial dose-finding portion of the study will be conducted at several clinical trial sites in Europe. The study may then be extended to additional territories in and outside of Europe. PRO044, which is our next most advanced product candidate after drisapersen, addresses a separate sub-population of DMD patients by inducing exon 44 skipping and is intended for approximately 6% of all DMD patients. PRO044 is in Phase I/II clinical development in Europe to assess the safety and efficacy of the medication for DMD patients with a mutation around exon 44 in the DNA of the dystrophin protein. Data from this study was presented at the World Muscle Society Congress in Asilomar, California this past October. An extension study is anticipated to begin in 2014. PRO045, which may have around 8% of all DMD patients, entered clinical trials in the first quarter of 2013. PRO052 and PRO055, intended for respectively 4% and 2% of all DMD patients, are in advanced preclinical development. Furthermore, together with GSK, we have embarked upon a global study to evaluate the natural history of DMD. This study is aiming to enrol up to 250 patients across the U.S., Europe and Latin America and we believe it may be very helpful for comparative purposes for the product candidates which we are developing in less prevalent patient populations with DMD. We recently announced the successful enrolment of the 100th patient in Natural History Study. The goal of this observational study is to characterize DMD at various stages of progression using the same measures used in ongoing clinical studies, such as the 6-minute walk test. No medication is being tested in this study. Patients in the study are assessed every six months for a period of three years to measure their muscle strength and function, in addition to how the disease affects their quality of life as the condition evolves over time. Investigators are observing the patients as they perform various physical tests, and assess their quality of life through survey questions. Furthermore, certain biomarkers are measured through blood and urine samples to investigate a possible correlation to disease progression. We anticipate that this study can ultimately help inform the design of future studies, capture biomarkers of safety and disease progression and to provide comparative data for the development of rare exons for which formal controlled trials may not feasible. I would now like to turn the call over to our CFO, Berndt Modig, who will discuss financial highlights for the quarter. Berndt?

Thank you, Hans. The consolidated financial statements of Prosensa have been prepared in accordance with IFRS as issued by the International Accounting Standards Board, IASB. The consolidated financial statements are presented in euros which is the Company’s functional and presentation currency. Prosensa's cash and cash equivalents as of September 30, 2013 were €86.7 million compared to €40.7 million as of December 31, 2012. Our cash consumption excluding cash flows from financing in the first three quarters of 2013 was €17.8 million. Revenue was €2.4 million for the third quarter 2013 and €6.8 million for the nine months of 2013 compared to €2.3 million and €5.5 million for the comparable periods in 2012, mainly due to a decrease in license income of €0.6 million and an increase in collaboration revenue of €0.7 million for the third quarter of 2013, and increased collaboration revenue of €1.4 million for the nine months ended September 30, 2013. Research and development expense was €4.9 million in the third quarter 2013 and €13.5 million for the nine months ended September 2013, compared to €3.7 million and €10.2 million for the comparable periods in 2012. Research and development expense mainly increased for the third quarter of 2013 as well as for the nine months ended September 30 due to ongoing Phase I/II study of PRO045 and PRO053. General and administrative expense was €1.9 million in the third quarter 2013 compared to €0.9 million in the comparable period in 2012. General and administrative expense was €5.8 million for the nine months of 2013 compared to €2.9 million for the comparable period in 2012. The increase is primarily due to share-based compensation expenses of €0.7 million and additional cost associated with operating as a public company. In the nine months period ended September 30, 2013, we also incurred €1.4 million in expenses recorded in G&A related to the IPO. Net loss for the third quarter 2013 was €4.3 million and €12.5 million for the nine months ended September 30, 2013, compared to €1.8 million and €6.9 million for the comparable periods in 2012. The outcome of the currently ongoing evaluation of drisapersen may have a material impact on our development plans and accordingly our operating expenses and cash consumption in the upcoming periods. We expect to be able to provide more detailed financial guidance once the drisapersen analysis has been completed and more is known as we move forward. I will now turn the call back over to Hans for some closing remarks. Hans?

Thank you, Berndt, and thanks to everyone for joining the call today. Again, we remain committed to be the pioneer in the DMD space and working very closely with key patient groups and experts in the field to further develop our innovative portfolio. We look forward to updating you as we know more. I now would like to turn the call back to the operator who will open the line for questions.

(Operator Instructions) Our first question comes from Joseph Schwartz with Leerink Swann. Please proceed with your question. Joseph P. Schwartz: I was wondering, when we get the results of your pre-specified post-talk analysis, what other plans or information will you communicate at that time, for example will you be giving us any update on your communications with regulators or your plans to do so?

As we mentioned in the prepared comments of this call, the analysis are currently ongoing in full swing. We are really working very closely with GSK in analyzing the data and looking at various perspectives on a number of parameters in there. So far the comment has been made that by the end of this year, we expect that these analysis will be finalized and completed, but in terms of what they actually will then encompass and when there will be any communication about it, so far no guidance has been given there, but the work is ongoing with full commitment and we are, as I mentioned, very, very busy with analyzing all the data. We have received numerous suggestions from the fields, both from key opinion leaders, from experts in DMD, from peer companies, from the patient community, from the financial community as well, and I really would like to thank everybody for thinking with us in the work which is currently ongoing, but it is premature to already give any guidance on what will be coming out of the analyses. And I'm having Giles Campion, our Chief Medical Officer, is sitting next to me here. Giles, maybe you can comment a little bit on the various things we are looking at in these analyses without of course giving any further guidance that we don't know about yet.

Thank you, Hans. There are a number of things that we would be looking at in terms of a proper analysis. As far as the Phase III study itself is concerned, the influence of known factors that affects the primary outcome, the 6-minute walk test including baseline 6-minute walk and age, and also looking at other markers such as the CK. We have the opportunity to be able to put together the other studies that we have carried out in this program, including the 876 study, the 117 study and the pooled analyses, and again to look at some of these sub-populations of patients to try and identify those that might respond. Joseph P. Schwartz: Okay, thanks. And could you walk us through some other scenarios that you could see, not applying any probabilities of course, but I would think the different outcomes that result from this analysis after you discuss the data in more detail with GSK could include, whether or not you are going to file or run another trial, are there any other potential scenarios here?

Joe, of course you will understand that it's premature to give any guidance on potential outcomes while the analyses are ongoing. So I would not like to read or attach any likelihood or probability to the various scenarios which I will be thinking second, but indeed, of course the most positive outcome would be that based on the current analysis of data ongoing and having discussed the data with the regulators, there may be a path forward based on the current data set, and again I am not attaching any likelihood or probability here but that is a hypothetical scenario. And of course that remains to be seen whether there should be follow-on studies or not or whether there should be post or pre-clinical studies, that's all in the scenario of an outcome which would provide a path forward for drisapersen. And the other side of this fraction of course would be that the ongoing analyses would not lead to positive risk-benefit relationship for drisapersen and then the compound will not be developed for it. But again, just answering your question on various scenarios, the analyses are ongoing and it is too premature to say which scenario will be applicable in any outcome of the analyses which are ongoing. Joseph P. Schwartz: Okay, great. Thanks. I appreciate you taking my questions.

Our next question is from Kumar Raja of Citigroup. Please proceed with your question.

This is Kumar R. in for Yaron Werber. Thank you for taking my question. So for the follow-on programs, when does the GSK need to opt-in, and also how much flexibility do you have in adapting this follow-on trials based on the analysis of the drisapersen data?

As we mentioned in our prepared remarks, we currently have beyond the drisapersen, three more compounds in clinical development at this moment and then two other compounds in advanced preclinical development, and of course what we would like to do is to learn as much as possible from the ongoing analyses of drisapersen, those in terms of patient populations, those in terms of endpoints. So, all these things are going to be taken into account in the further follow-up of the study programs which we are having right now. Your question about GSK, GSK has indeed an opt-in right on a number of those programs. They have the global exclusive option on PRO044 on the moment that option criteria are met. They also have an opt-in right on either PRO045 or PRO053 depending on which compounds will meet the option criteria first, and if GSK decides to opt-in for such a compound, that will then again be an exclusive global option or license, although we have then as Prosensa the possibility to opt-in for that specific compound and to exercise commercial rights in select European territory, and that same principle applies for PRO052 and PRO055 as well. So I think those are the two answers to your question, and maybe Giles, you want to give a little bit more insight into what essential outcomes there could be, how we could learn from the drisapersen analysis for our future programs.

I think the advantage of the drisapersen program is that it's unprecedented in terms of scope and number of patients. So I think it gives us a great opportunity to learn more about the disease of many placebo patients there and will help us gain insights in terms of how we may need to adapt to, if at all, our follow-on program. So clearly those analyses are not only important in terms of deciding the right product for drisapersen but also will help guide the subsequent programs as we continue to conduct studies.

Our next question is from the line of Chris Marai of Wedbush. Please proceed with your question.

Thanks for the update. I was wondering if you could help us on a few questions. Number one, the follow-on compounds and specifically PRO044, it appeared to look more potent than drisa in terms of production of dystrophin. I was wondering if you could elaborate on how these compounds might differ from drisapersen so that we could kind of understand where these may lead us in the future. And then also given the difficulties with the 6-minute walk test in DMD and the variability in these patient populations, how have your FDA interactions been going with respect to any flexibility on the sub-group analysis or other flexibility in analyzing your results?

First of all, regarding the follow-on compounds, PRO044 and PRO045 and PRO053, all of which are in the clinic and do have a higher efficiency in the skip of the [development actions] (ph). If you go back in time, PRO051 was licensed together with the know-how and the patents from Leiden University Medical Center and Prosensa embarked on this long journey, and PRO045 and PRO053 as the most recent compounds going into the clinic, were developed by Prosensa as part of the collaboration with GSK. So, as you know the relationship with GSK started in October 2009 and throughout the years we have received milestone payments which also have facilitated us to develop PRO045 and PRO053 and PRO044 to the states where they currently are. And certainly in the case of PRO045 and PRO053, our discovery process of selecting these compounds for further clinical development has been fairly rigorous. We have developed and synthesized up to 60 compounds in order to pick the best compounds for further clinical development. So, the process by which those compounds have been identified and selected has been more rigorous you could say than for PRO051, and don't misunderstand me, I'm not discounting here PRO051 assets, but just to explain how we have pioneered and how we have developed over time a rich portfolio of compounds. So that's about the first part, and maybe Giles wants to add a few comments about PRO044 as well as about the findings there and the question of Chris about its higher potency or [issued] (ph) potency?

The only thing I would say is that as far as the initial Phase I/II study was concerned, I would just remind people on the call that this was just five weeks of dosing, so weekly dosing. So I think the key endpoint for the all these developments at least for the time being is the clinical endpoint. So I wouldn't read too much in terms of the dystrophin. We are using that as you know and as we said after the results of the 117 dystrophin results, as more as a kind of mechanism of action rather than definitive endpoint. The 6-minute walk we still feel is an important endpoint, to get to another part of your question regarding interaction with the regulators. I think certainly the emerging data that have come from some of the publications of Craig McDonald I think have emphasized its utility in terms of ability to predict subsequent markdowns and outcomes. It is also being – there's been an effort there to kind of [indiscernible] clinical meaningful differences and other important aspect of determining any clinical endpoint. There is variability, and I hope that with the work that we're doing in terms of looking at sub-populations, we may understand more about that variability and how to minimize the effects and potentially looking at it with other parameters. One thing that we are doing in terms of our follow-on studies is looking at our biomarkers and of course imaging, which may be important.

And just to emphasize what Giles was saying regarding the regulatory interactions, I would like to remind everyone on the call that we are very happy that GSK obtained Breakthrough Therapy designation with drisapersen earlier this year, and even though it has been rightly mentioned by the FDA that by no means this is an easier way of having a pathway to approval, by no means, but it will allow for preclinical and good interactions with the FDA, and of course we hope that that will be the case as well in the situation with the vast database we have now of the Phase III and the previous studies in totality. But you can understand that actually we do not comment upon the regulatory interactions with the FDA as such. They are confidential in nature.

Our next question is from the line of Debjit Chattopadhyay of Emerging Growth. Please proceed with your question.

Couple of questions, if I may. First, in terms of the follow-on compounds, if they do have a higher skipping efficiency, what does that mean in terms of the side effect profile of the underlying chemistry?

The short answer is, we don't know yet of course because that's indeed – that's premature to make any definite predictions on that, but the process by which these compounds were identified and selected were through a large number of design sequences of oligos. Again, that then goes in a number of various [phases] (ph), and finally having a number of these compounds go into preclinical safety studies as well, trying to lead in the best compounds and with the knowledge of where they emerge. Giles, would you give some feedback on that as well.

Yes, in terms of the process, designing these oligos now is something that we have gained a lot of experience, and Judith van Deutekom, the VP of Discovery, has been working on this area for 15 years. And so she has now built up a lot of experience in terms of oligo design. We started with about 60 oligos, look for the most effective in terms of efficiency of skipping, and then we have a number of criteria to deal with some of the compounds on the basis of their characteristics and various safety tests, so that we end up with the best compound. So I think we have a much more rigorous process of selection of our optimum candidate. And the importance of having increased efficacy or efficiency of exon skipping gives us the potential of having a larger therapeutic margin. However, I would reiterate what Hans just said that that really has to be proven in the clinic, and that's what we are trying to do now.

In terms of 6-minute walk test, the test has been now kind of caught in the spotlight for the wrong reasons, and FDA is basically looking at whether 48 weeks is enough you need to go to 96 weeks, any thoughts on what that changed, why they are thinking about 96 weeks and does it even make sense given Natural History's data?

It's difficult to make comments about the thinking of the FDA of course, but again, if you go to what we have observed in the DEMAND II study, where we saw after 25 weeks of treatment, in the 6-minute walk test, we saw explicitly significant and clinically meaningful outcome in that study on a clinical [indiscernible] outcome parameter and that effect was maintained at 49 weeks and p-value of 0.051. So I think we had shown that with 25, or in this case 49, weeks of treatment, a clinically meaningful effect can be achieved. The same counts for the 876 study, DEMAND V study, where we saw after 24 weeks of treatment we saw a 27 meters differentiation between the 6 mg/kg treatment and placebo, and albeit it was not a statistically significant outcome but it is very encouraging and supportive of the other placebo-controlled study. So of course if we [do longer on the] (ph) treatment then one will get more information, and we have had the moment apart from the long-term extension study where a small group of boys, in total of 12 boys, were treated for up to four years at a 673 study where some boys could walk at the beginning of this extension study, and of those 10 boys, eight boys can still walk today, and if you then look at the other extension study, the largest study which we have, that's the so-called 349 study, where boys who were in the 117 study or in the DEMAND III 044 study, those boys could go to the extension study which is the 349 study and that data is being generated as well and that will provide a lot of insight into longer-term exposure for boys who previously were participating in a lot of the placebo-controlled studies.

Hans, one last question, supposing the worst possible outcome with drisapersen that there is no path forward to take drisapersen back to the clinic again, would you then consider partnering with your competitor on the other exon 051, at least on the European segment?

It's rather hypothetical at this moment in place because we really are in the midst of these analyses, and as I mentioned, we are very committed to leave no stone unturned to try to find out whether there is a way forward here for boys affected by DMD. We see that same level of commitment with GSK and that should be our very first priority at this moment in time, to really understand whether and how we can understand the Phase III results in the larger context of all studies done with drisapersen. That process is ongoing right now. So I would like to leave it there and not speculate on potential or other outcomes of this analysis.

(Operator Instructions) At this time, there are no additional questions. I will now turn the floor back to Hans for closing comments.

Thank you very much, operator, and thank you all again for joining this call. As mentioned, we will keep you updated as data are progressing and when we are in a possibility to do so. For now, thanks for your interest in Prosensa. Good day, good afternoon, good morning.

Thank you. This concludes today's teleconference. You may disconnect your lines at this time. Thank you for your participation.