Todd James - Senior Director, IR & Corporate Communications Habib Dable - President & CEO Kevin McLaughlin - CFO Matthew Sherman - Chief Medical Officer.

Geoffrey Porges - Leerink Partners Carter Gould - UBS Andrew Berens - Morgan Stanley Alethia Young - Credit Suisse Mike King - JMP Securities Christopher Marai - Nomura Whitney Ijem - JP Morgan Edward White - FBR & Company.

Good day ladies and gentlemen and welcome to the Acceleron First Quarter Earnings Conference Call. At this time all participants are in a listen-only mode. Later we will conduct a question-and-answer session and instructions will be given at that time. [Operator Instructions] As a reminder, this conference is being recorded.

I would now like to hand the floor over to Todd James, Head of Investor Relations and Corporate Communication at Acceleron. Please go ahead, Sir..

Thanks, and welcome, everyone, to Acceleron's first quarter 2017 earnings conference call. The press release reporting our financial results, in addition to the presentation for today's webcast, are available on the investor's media page of the corporate website at www.acceleronpharma.com.

In addition to our financial and operational results, we'll be reviewing highlights from our luspatercept Phase 2 presentation from the 14th International Symposium on MDS that took place over the weekend in Valencia, Spain. The full conference presentation is available in the science section of our website.

Joining me in the room today are Habib Dable, our Chief Executive Officer; Matthew Sherman, our Chief Medical Officer; Kevin McLaughlin, our Chief Financial Officer and Chris Rovaldi, Senior Vice President, Operations and Program Management.

As a reminder, we will be making forward-looking statements regarding our financial outlook in addition to regulatory and product development plans and research activities. These statements are subject to risks and uncertainties that may cause actual results to differ from those forecasted.

A description of these risks can be found in our most recent Form 10-K on file with the SEC. I would now like to return call over to Habib Dable, our Chief Executive Officer..

Thank you, Todd. Good morning, everyone and thanks for joining us today. It's clearly an exciting time at Acceleron with recently provided program updates over the past few weeks and additional updates announced this morning. Based on faster than expected rates of patient requirement in the MEDALIST and BELIEVE Phase 3 studies year-to-date at Celgene.

Our luspatercept collaboration partner recently announced that we expect full patient enrollment to be achieved this quarter versus our previous guidance of the second half of 2017. This should now put us in the position to report top line results from the Phase 3 trials by the middle of 2018.

We at Celgene also announced that we plan to initiate a new Phase 3 trial with luspatercept and first-line lower risk MDS patient in early 2018. This decision is supported by results presented over the weekend at the MDS Symposium that Matt will be discussing later on this call.

For the ACE-083 program, we announced plans to initiate a second Phase 2 trial in neurological disease called Charcot-Marie-Tooth disease, or CMT that causes muscle weakness in specific muscles. We expect this two part Phase 2 study to begin in the middle of this year with the part one dose escalation results available in 2018.

Our team recently hosted an educational webinar to discuss the background on CMT and our Phase 2 trial design. We were joined by a leading neuromuscular expert, Dr. David Walk [ph], Associate Professor of Neurology and Director of the ALS and CMC Centers of Excellence at the University of Minnesota Medical Center.

A reply of this event is available in the events and presentation section of the investor's media page on our corporate website. While we are working on ACE-083 trial start-up activities in CMT, enrollment and treatment are ongoing in the part one dose escalation stage of our Phase 2 trial in Facioscapulohumeral Muscular Dystrophy or FSHD.

I'll now turn the call over to Matthew Sherman, our Chief Medical Officer, to review highlights from our luspatercept two presentations at the MDS from this past weekend..

Thanks Hadib, hi, everyone. Our team just returned from a 14th International Symposium on MDS that was held in Valencia, Spain, from May 3 through May 6. There were two clinical luspatercept presentation at the conference.

We had a Phase 2 PACE study update that was presented by Uwe Platzbecker from Dresden Germany, one of our principal investigators for the study. We also highlighted the poster presentation that discussed the Pk/Pd response relationship of luspatercept in MDS patients.

The Phase 2 trial presentation focused on the lower risk MDS expansion cohort patients not eligible for our ongoing MEDALIST Phase 3 study.

The new expansion cohort patients include erythropoiesis stimulating agent or ESA naïve patients where ring sideroblast positive with baseline erthyropoetin levels below 200 and ring sideroblast negative patients with any baseline EPO level regardless of VSA experience.

We refer to patients with these baseline features as first-line lower risk MDS patients. Before going into our data, I would like to provide some context by outlining results from two ESA Phase 3 studies presented in 2016.

On the left side of the slide, we are showing the darbepoetin alpha Phase 3 study, primary outcome measure, the International Working Group's Hematologic Improvement in the response or IWG HI-E which is at least a 1.5 gram per deciliter increase in hemoglobin sustained for eight weeks.

In this 147 patient Phase 3 trial, 14.7% or 11 out of 75 patients in the active arm net the primary endpoint. All 11 responders had baseline EPO levels below 100 and there were zero responders above 100 EPO levels of baseline. Only one of the 11 responders had a baseline transfusion burden.

27 out of 28 patients entered the study with a baseline transfusion burden do not meet the primary endpoint response. On the right side of the slide, we are viewing the Epoetin Alpha Phase 3 primary endpoint analysis. This study also used the IWG HI-E response criteria as the primary endpoint.

In this 130 patient Phase 3 trial, 31.8% or 27 out of 85 patients in the active arm meet the primary endpoint. This study stratified responders by baseline EPO levels above or below 200 with all 27 responders having baseline EPO levels below 200 and zero responders above 200.

These results led to Epoetin Alpha recent approval in France for the subset of lower risk patients with baseline EPO levels under 200. It is also important to note the low placebo response rates in each of these studies.

On this slide we've broken down response rates in our luspatercept Phase 2 by ESA exposure with patients either having received prior ESA treatment or never received an ESA and are ESA naïve.

When looking at the IWG HI-E response criteria, 51% of ESA naïve patients treated with luspatercept achieved this clinically meaningful response criteria; this is the similar response rate to patients who have had prior ESA treatment.

On the right side of the slide, we are evaluating red blood cell or RBC transfusion dependence response which is derived as a period greater than or equal to eight weeks without receiving transfusions.

48% of ESA naïve patients treat with luspatercept achieved transfusion independence while 33% of prior ESA treated patients also achievement transfusion independence. The swimling [ph] chart on this slide shows patient response by duration of RBC transfusion independence for ESA naïve patients receiving luspatercept treatment.

Each line represents a patient's treatment period. A solid blue section of the line identifies the transfusion-free period of at least eight weeks. RBC transfusion events are shown with red dots for each patient. The right facing arrows at the end of some of the lines means that treatment is still ongoing.

The median duration of transfusion independence is 8.7 months with a range of two to 27 months. On this slide we are looking at luspatercept response rates in RS negative patients regardless of ESA experience stratified by baseline EPO levels.

In the RS negative patients, 6 of the 14 are 43% of patients achieved the HI-E response; and 4 out of 7 or 57% achieved RBC transfusion independence. At baseline EPO levels above 500, RS negative patient response rates dropped significantly. Let me summarize the key takeaways from our Phase 2 update.

We achieved high response rates in the lower risk EPO level bans where physicians currently use ESAs off-label, including both RS positive and negative patients. These results compare favorably through historical rates of response with ESA treatment.

More specifically in RS negative patients, response rates are high in patients based on EPO levels below 500. Luspatercept was generally well tolerated for patients on treatment upto and now exceeding 24 months of drug exposure.

These updated Phase 2 results support the decision to expand luspatercept's clinical development into a first-line lower risk MDS Phase 3 trial in early 2018. I will now turn the call over to Kevin McLaughlin, our Chief Financial Officer, to run through the financials for the quarter..

Thanks, Matt. Our cash, cash equivalents and investments as of March 31, 2017 were $213.2 million. This compares to December 31, 2016 cash, cash equivalents and investments of $234.4 million.

As a reminder, we believe that our existing cash, cash equivalents and investments will be sufficient to fund our projected operating requirements into the second half of 2019.

Collaboration revenue for the first quarter was $3.7 million, the revenue is all from our Celgene partnership and is primarily due to cost sharing revenue of $3.6 million related to expenses incurred by the company in support of our partnered programs.

Total cost and expenses for the first quarter were $29.5 million, this includes R&D expenses of $21.7 million and G&A expenses of $7.8 million. Other income net for the first quarter was $500,000, primarily due to interest income. The company posted a net loss for the first quarter ended March 31, 2017 of $25.4 million.

I will now turn the presentation back over to Habib for final remarks..

Thanks Kevin. So looking ahead we expect several key milestones over the next 12 to 18 months. For luspatercept program, we expect to complete enrollment in both, the MEDALIST Phase 3 trial in MDS and the BELIEVE Phase 3 trial in beta-thalassemia in the second quarter of 2017.

In addition to our ongoing Phase 3 studies, we plan on initiating three clinical trials with luspatercept. In early 2018, we expect to initiate a Phase 3 trial and first-line lower risk MDS patients.

Phase 3 trials in myelofibrosis and in non-transfusion dependent beta-thalassemia are planned to begin by year-end and we're also expecting to report additional Phase 2 study results at medical conferences throughout the year.

I would like to note that given the Phase 2 MDS update this last weekend at the MDS Symposium, our MDS presentation at E-HI [ph] next month will be about a two month update. We look forward to providing a larger update at ASH [ph] in December.

Turning to ACE-083, we anticipate having initial data from the Part 1 dose escalation arm of the Phase 2 FSHD trial by late 2017. This update will include results from dose cohort 1. Our trial and CMC will start mid-year with Part 1 results expected in 2018.

Moving to dalantercept in RCC [ph], based on recently reaching this 82nd PFS event which is the prespecified number event determining results for the primary endpoint, we now expect to report topline results on the primary outcome measure of progression free survival this quarter.

We also continue working towards initiating a Phase 1 healthy volunteer study of ACE-2494. Finally, given all of our recent progress in the clinic, we now plan to host a research and development day later this year to discuss our ongoing preclinical research and provide additional details for some of our planned clinical trials.

Stay tuned for further event details over the next few months. And with that, I will open the call to questions.

Operator?.

[Operator Instructions] Our first question comes from the line of Geoffrey Porges from Leerink Partners..

Thank you very much and congratulations on the results in ESA naïve and low-risk MDS, very interesting. First, I don't know if you could give us a sense of what proportion of low-risk MDS patients have baseline EPO less than 500; just to help us in sort to mentioning this opportunity.

And secondly, the summer plots that you presented for the patients who are transfusion independent for eight weeks have a concentration of transfusions when patients fail, they seem to be repeated transfusion; so wondering is that to be expected and do you believe that there is any loss of activity of the drug with prolonged exposure or are you seeing any neutralizing antibodies to the drug [indiscernible] and activating it? I mean my last question is a does [ph] question which is, you use -- appear to be using wide-based dosing but would you envisage ultimately having standardized dosing and would dosing differ between the low risk and ESA naïve and the ESA experienced populations? Thanks.

Apologies for all the questions..

Thanks, Geoff. So with the details of the study, I will hand it over to Matt, and then I'll follow up with that in terms of the population in terms of the percentages. .

Hi Geoffrey, this is Matt. So let me take the second question you're asking, which related to win-win class and the transfusion seen sometimes in patients after they'd have a prolonged period of transfusion dependence.

As you know, the average age of onset of MDS patients is that 70 years in our study, the median age was 72 years in patients are often to the Phase 2 trial. So the disease in the elderly many patients have co morbidities. And so if you look out over several years in these patient's history has often-other medical illnesses of problems that arise.

So might be related to a periods of infection for example, when patient might have -- have a bacterial oral affection they're sick they need a boost in transfusions a period of time.

More specifically for one of our patients there was a period of GI bleeding, that was unrelated to the drug that occurred to another issue and that requires some transfusions as well. So it is those kinds of events that account for these small bursts of transfusion, we've not seen any drop off of the efficacy of the drug though over time. .

Great, thanks. .

And then in terms of weight based dosing question, I think we’re very comfortable with the Pk/Pd modeling that we've done for this protein to show that the efficacy that we're seeing does require weight base dosing, so there's no plan to do flat in the near future must have or so..

And then, Geoff, regarding your question regarding the percentages patient below EPOS 500, we estimated the majority of those patients that will be from zero to 500 probably somewhere around 70% to 80%..

Right, thanks very much for all the answers, appreciate it..

Thank you, and our next question comes from the line of Carter Gould with UBS..

Good morning guys, thanks for taking my questions.

I guess first one on the frontline MDS study, the language being used there fairly broad in first-line treatment, somewhat delicate given the partnership with Celgene but can you definitively answer will there be RS negative patient enrolled in that study? And should we expect any sort of cut off of based on EPO level and in terms of inclusion criteria.

And then secondly, just any comment on the duration you've seen so far in the RS negative segment relative to what we see in RS-positive segment. Thank you..

Hi Carter, this is Matt. So yes, right now describing the frontline study because I think really it builds on the excitement that we've seen in this, yes they may be of population, there's -- there is tremendous enthusiasm that came out of the -- the Symposium meeting in Valencia just over last week and this weekend.

Highlighting which covers up as one of the leading drug now and phase three development, living into the frontline setting sets us up for going head-to-head to and ESA therapy. The data that we generated ratios with very roust rates we are seeing with patients in baseline EPO levels within 500, which is the majority of patients.

ESA-naive population both importantly both are as positive in ours negative patients. The duration of responses although it's still early days, there is not sure that there's a significant difference between those two populations.

So if you move forward with this program, there will be more details forthcoming, those will be able to update folks on the specifics of the status line and collaboration with Celgene now towards later this year as -- as we have the details so to discuss..

Thank you..

Our next question comes from the line of Andrew Berens with Morgan Stanley..

Hi guys, thanks a lot for taking the question. My question on efficacy of the RS-negative population have been answered but I have a couple questions on the safety. You mentioned in the press release that there were several occasions of anxiety that were classified grade three and drug related.

Can you give us some color on that that, and is there any mechanism that could suggest this is related to something the drug is doing. Thanks..

Hi Andrew, again this is Matt. So safety profile that this drug actually been very, very well tolerated over the multiple years now that it's been in our many years now been in development.

So the small numbers of related great three adverse events that we admitted, have not been anything that we can say specifically related to the mechanism of the drug. Then again the currents of those generally have been very low frequency. .

Okay, but was there a reason that the investigator determine on the drug related, I think that's what the [indiscernible]?.

Yes, I mean that this is again always in the eyes of the investigators understanding of the patient, that generally the temporal relationship of the event to the administration of the drug but it's -- it's and it's much more of an art than a science.

And there really requires a randomized control trial to -- to delineate whether or not any of these really have an increased frequency. And treatment population versus the control population. They have to know not -- not reach the level of being a serious adverse event, so they were generally more -- more tolerated by patients..

Okay. Is that something that is those two pro-fusion cited beyond this patient population. .

Yes, certainly given the elderly population they have a number of co morbidities as well too so.

Now with cardiovascular disease being a primary issue among these patients could have that active, cardiovascular disease such as the recent MRI but they certainly have had -- many of them have had long standing history so hypertension, atherosclerotic heart disease, [indiscernible]; altogether not a surprise that there would be the currents of other adverse events just over the concourse of patient participation into a multi-year clinical trial.

.

Okay, thanks a lot, appreciate it. .

Thank you, and our next question comes from the line of Alethia Young from Credit Suisse. .

Hey guys, thanks for taking our questions. Maybe just one if you had any kind of hypothesis on why they are as negative and hyper baseline didn't exhibit response, just anything kind of that you're hypothesizing in there and then I just wondered as relating to the -- two luspatercept which can roll faster than expectation.

Was it consist of dynamic that kind of that -- the traffic and minimum awareness of physicians or kind of what drove your faster timeline enrollment? Thanks..

Hi Alethia, this is Matt.

So for the first question regarding to the lack of response in patients with high baseline EPO level, I think that really does reflect the stage of their disease, those -- those with patients who really bone marrow, almost consider to be burned out marrow, they've been flocked significantly with their own endogenous EPO levels in there -- they've tried to overcome the ineffective erythropoiesis to the point where it's pretty much exhaustion of the marrow.

So that setting luspatercept has had limited activity as does ESA and certainly as does any other therapy trying to increase red blood cells. So not necessarily surprised more reflection of the advanced nature of those patients disease.

Regarding the -- accelerated enrollment of -- rapid enrollment of the Phase 3 trial, again I think it really reflects just the building enthusiasm momentum with opportunity for luspatercept patient opportunity, also reflect those other very limited options for these patients.

So together that really drove a much more rapid uptake of -- of participation, and recognizing even with the randomized control placebo controlled trial, which sometimes limitations to enrollment many patients obviously recognizing may not want to be on the placebo age but given the lack of opportunities and the excitement building for luspatercept, we were thrilled with -- with the enrollment.

.

Thank you..

Thank you. And our next question comes from a line of Mike King with JMP Securities..

Good morning guys, thanks for taking my question and let me also add my congrats on the data that you presented over the weekend.

I was wondering you started keep drawing down on this RS-negative population, but I'm just wondering if -- I understand Matt your explanation for one of them may not be responding to luspatercept in the setting, I just want to -- is there any read through perhaps to myelofibrosis, it's not quite the same situation but you do have an exhausted marrow in NMS [ph] but you've still seen some pretty interesting responses there, so I am just wondering how we reconcile those two findings.

.

Hi Mike, so yes, first in regards to your question what I think you're referring to is not a RS-negative patient, RS-negative patient with high EPO level. .

Yes. .

And that context thinking about marrow, I think it is very different situation though in the myelofibrosis, in the myelofibrosis patients their marrows aren't actually highly reactive marrows accounts with the fibrotic nature in -- in their in their marrow.

So they as we showed last year you're -- you're quite familiar with the data that we presented with [indiscernible], you know, high degree of erythropoietin response in patients who had really advanced and that that was the investigator initiated trial that was done by surgical for cellstack at MD Anderson.

And on that basis, certainly moving ahead to initiate the Phase 2 trial of luspatercept in patients with myelofibrosis, so still I believe there's a high degree of enthusiasm optimism right now to be working with NMF [ph] patience, very distinct disease than MDS..

Thank you for taking the question. All the others I pondered where answered, so thank you..

Thank you and our next question comes from a line of Christopher Marai from Nomura..

Hi, good morning, thanks for taking my question.

Maybe will take it over to a [indiscernible] I am just wondering if we could further elaborate perhaps on the addition of CMT muscle weakness is really a -- is really an issue for some of these patience and do you expect that the volume enhancement that you are going to see [indiscernible] with muscle weakness.

And perhaps you can point to data that might suggest your approach is differentiated in that respect to other myelofibrosis? Thank you. .

Hi Chris, let me answer the question about them the -- the role of ACE-083 and CMT and make a comparison to FSHD as well too.

So these are two neuromuscular diseases that we targeted now for Phase 2 trials to investigate the role of ACE-083, ACE-083 first is a broader acting agent in just a myostat inhibitor; so as we discussed inhibits multiple negative ligands they can regulate muscle growth and functions.

But these six diseases are distinct I think there is two pronged approach to the important ones to recognize from an FSH dystrophy there is an impairment in the muscle itself it is a muscle dystrophy.

So our expectations to increase muscle strength in that setting, in CMP the muscles impact is just the innovation for the nerve to the muscle that isn't here. So the muscle itself is relatively healthy into undergoes atrophy after no prolonged period of this innovation.

So that's setting again increasing the volume, the strength, the function of the existing muscle to help those patients overcome their impairment. We had a webinar a month and a half ago, about the study, I think it's really informative for folks to actually try to listen to some of the details that were preserved by Dr.

David Walk [ph] but these are patients were pretty troubled by their -- by their illness the foot drop presenting with a high step gate [ph] leading to trips and falls in these patients, without any therapeutic available for these patients other than just the orthopedic bracing of their -- of their ankle there's quite incoherent in their mobility.

So the ability of FSHD to increase strength I expect will be very significant benefit, for these patients.

I guess I should also mention the ongoing pre-clinical [ph] work that we've done as well have supported the role of the ACE-083 to increase muscle function across a wide number of preclinical models and different neurological diseases, so again that adds to the evidence from the potential benefit for the agent in these Phase 2 trials..

So just to be clear you expect not only you'll see the volume on enhancement with your myostat inhibition but also an increasing in strength?.

Exactly, so the trials in designing two part trials, there's an open label there somewhere both trials are similar in designing, first an open label part of the trial which has a small dose escalation opponent and in that part we're going to be focusing primarily on muscle volume, the primary activity as we demonstrated on healthy volunteers, and in part two randomized and placebo-controlled and in that setting not only muscle volume will be evaluated, but also muscle strength using fixed stress testing and hands on a monetary testing and a number of functional outcome measures.

I think as the as the trials will move along will spend a little more time talking on the important of these outcome measures.

These include things such as a six minute walk test you are familiar with that, but also the 10 meter walk run of [indiscernible] test, activity measures of the upper extremities called pull test which is performance of the upper limbs and basically in the CMP population, a test called the burden balance test. And this is a 14 component test.

Looking at patients ability to have -- have a good balance either by standing or sitting on one foot, turning in 360 degrees. So really quite sophisticated testing of their muscle function.

Furthermore, both of these studies we're actually looking at that the patient gate, so we are using highly sophisticated gate analyses to measure their ability to -- to improve their emulation. So I think I will excited to see the state as a -- as a young fold [ph] the over the next year. .

Okay thank you. .

Thank you and our next question comes from the line of [indiscernible] from Citi..

Hi guys, thank you so much for taking my question, and then congratulations on the data presented over the weekend.

So for the ESA-naive I know you said you're going to talk about details later, I was just curious since you've presented both HIV and transfusion dependent data could you talk about what the potential primary point could be and also for myelofibrosis, just wondering when we can hear more about the trial design mainly but what patient population you wish to target, thank you so much.

.

Again, this is Matt answering the question.

So good questions but I don't think I have a lot of information right now to share with you, as we get further along with this specifics of the design for the command study in the first line MDS patient population to be able to talk specifically, my end point would be and the specifics of the patient population, I know people would want to look forward to the specific eligibility criteria that we certainly shown the -- the range of activity we've seen in the lower Phase [ph] level of patience and ESA-Naive population as well too, but I think that that's as far as we can talk about the specifics today, but stay tuned later in this year.

In terms of myelofibrosis, I think it's really similar as we get a little closer, get a little bit more keyed up to be giving a Phase 3 trial, I think together with our partners Celgene will be able to align the -- the eligibility criteria in the specific end point and the study population for the MF study as well too. .

Okay, great thank you.

Can I sneak in just one more question about the launch itself; just wondering how we will receive the data, is there any likelihood of the data at ASCO or do you expected press release the data now that it's been advanced from second half to the second quarter?.

Yes.

So I can start to let people know where we are with that study if I can jump in about how the data will be released too, but we did talk about we -- we reached our 82nd PSFGN [ph] as that was prospectively prescribed in the study designed to do the analysis for the top line results, to show the effect of luspatercept combination with exutinib [ph] versus single agent exutinib [ph] plus placebo.

We've met a second event and we also completed the enrollment of 130 patients, so just now doing the analysis. And we can talk about that when we have the data presented..

Sure..

So we are at database analysis now, we've already passed through the late breaker time period for [indiscernible]; so you could expect that would just be a press release from us outlining the top line results. .

Okay, thank you so much. .

Thank you and our next question comes from the line of Whitney Ijem from JP Morgan. .

Thank you for taking the question. I guess one quick one for me and just on ACE-083 and FSHD data later this year how do you tend to communicate that and to last question should we expect that press release or medical commenter or that in [indiscernible] event, how should we be thinking about that. .

Hey Whitney, it is Todd.

Yes they're multiple muscle conferences in the second half of the year but most likely we will just end up giving out a top line press release on dose cohort 1, late in the year and then you could expect further details from that potentially at the muscular dystrophy association conference in March or one of the muscle conferences early in 2018 for dose cohort 1..

Okay, thanks. .

Thank you and our next question comes from a line of Ed White with FBR & Company..

Hi guys thanks for taking my question, I think there most my questions have been asked, so I'll just ask on the luspatercept Phase 2 data I the first line lower risk MDS patients, are you going to have continue following patients and provide an update on expansion studies every six months like you're doing with the earlier study -- Phase 2 study. .

Hi Ed, thanks for the question, so yes that was actually exactly the plan just put into context when we did the first part of the Phase 2 study we had a total of 58 patients from the first part through the first extension cohort.

The second extension cohort including RS-negative patients was probably 50 additional patient, 31 of those patients were available for this update at the Symposium meeting.

So we anticipate approximately 24 patients that we will have data so -- there will be [indiscernible] obviously for 2017 to include the remaining patients who are enrolled, as well as showing the extension; you know, the durability of activity on these patients as we have done over surplus years for the first cohort of patients..

Okay, great. Thanks, that's all I have..

Thank you. [Operator Instructions] Our next question comes from the line of Paul Choi with Barclays..

Hi guys, thanks for taking the question. This is Jason on for Paul. Let me also extend my congratulations for the data.

Just a few quick questions, I know we've revisited the EPO question but you know, with regards to response, does that mean that if the patient has kind of higher and higher base line levels of EPO there is less of an effect? Or is it kind of just the step-wise function where around 400/500 -- the efficacy goes away? And then, just regards to your [indiscernible] products, kind of curious, there are couple of patients who -- it looks like are continuing therapy even though they had a robust response, if you could just shed a little light onto that, you know, why -- why patient might have discontinued? Thanks so much..

Hi Jason, so -- yes, in regard to your first question about EPO level; it's really tends -- it tends to be more of a drop-off, so when we showed the data with various cuts of baseline EPO levels, less than 200 and then the grouping between 200 and 500; you know, there was very little difference in the response rate for the HI-E response; over 63% of less than 200 versus 53% for the 200 to 500 baseline EPO population.

Greater than 500 though it did drop down to 27%, so it's that cut-off of 500 that -- less [indiscernible]; you know, we've seen this drop-off inactivity.

Yes, Phase really are much more active though in a much lower range there and as we highlighted the Phase 3 trials for Darbepoetin and Epoetin, you know, there the activity is very much limited to baseline EPO levels, less than 100 or perhaps upto 200 but really not even indicative for patients between 200 and 500 grams [ph], so we have -- I think a clear benefit in that patient population.

In terms of [indiscernible], you know, there are patients who dropout for various reasons, sometimes -- you know, I don't want to really go into the details where the patients plot [ph] but sometimes it's obviously just due to social reasons for patients participating in the clinical trials, travelling, again these are older populations sort of coming in with a frequency of visits and trying to make that trip.

It was I think in Germany, you know, CARE for MDS patients is lot more centralized as many of these patients travelling 50, 60, 100 kilometers to get to their clinic for treatment, so part of that I think, you know, it has an impact on the patients involvement in the trial overtime..

Awesome. Thank you so much for taking the questions..

Thank you. And our next question comes from the line of Mike King with JMP Securities. Mike, your line is open, could you check the mute button please..

Sorry about that, can you hear me now?.

Yes, sir. Please go ahead..

My apologies.

Just wanted to -- sorry, again, [indiscernible] in front of efficacy you guys have seen buy just curious Matt, it's just been the answer of the previous question, you talked about sort of social reason for patient withdrawing from the trial; I'm just wondering is there for patients who stop responding, is there a biological underpinning to that? Do they stop making colony forming units or is it more about patient decision to -- you know, I've been response and I feel good about that, I can move on.

I'm just wondering if we can ascribe different reasons for why patients didn't continue on the trial?.

Hi Mike. So they said several of them were just for social reasons for the patients willing to participate in the co-trials such as this and given their age.

You know, sometimes it was disease progression; you know, these patients do have progressing unrelated to -- well, they can maintain their anemia but -- I'm sorry, their hematologic response to luspatercept but they can have progression of other underlying MDS.

So there is other reasons obviously for these patients coming off study; but this is -- you know, this didn't seem untoward compared to other studies that we've looked at in terms of patients discontinuing..

Alright, okay..

I mean as a physician who has treated MDS in the past too, I think this kind of activities is fairly impressive activity and I think that was reflected by the enthusiasm that both the investigators from the trial, as well as from the general MBS community appreciate it at the MDS Symposium Conference given the very limited options that these patients have.

It was clearly very enthusiastic reception for the data at the meeting in Valencia..

Alright, thank you..

Thanks Mike..

Thank you. And that concludes our question-and-answer session for today. I would like to turn the conference back to Acceleron management for any closing comments..

Yes, thank you, operator. So obviously an awful lot of interest and excitement over the recent data announcement. So I thank you all for your questions and I do look forward to meeting with you at some future investor conferences and medical meetings as we head into December month and wishing you all a great day. Thanks everybody..

Thank you..