Good afternoon, ladies and gentlemen and welcome to the aTyr Pharma's fourth quarter and full 2018 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. As a reminder to our audience, this conference is being recorded for replay purposes. It is now my pleasure to hand the conference over to Jill Broadfoot, aTyr's Chief Financial Officer. Ms. Broadfoot, you may begin.

Thank you, Carmen and good afternoon everyone and thank you for joining us today to discuss aTyr's fourth quarter and year-end 2018 operating results and corporate update. We are joined today by Dr. Sanjay Shukla, our President and CEO. Sanjay will provide an update on our corporate strategy and the clinical development of ATYR1923. I will then review the financial results before handing it back to Sanjay to open it up for the question-and-answer session. Before we begin, I would like to remind everyone that except for statements of historical facts, the statements made by management and responses to questions on this conference call are forward-looking statements under the Safe Harbor provisions of the Private Securities Litigation Reform Act of 1995. These statements involve risks and uncertainties that can cause actual results to differ materially from those in such forward-looking statements. Please see the forward-looking statements disclaimer on the Company's earnings press release issued after the close of market today as well as the Risk Factors in the Company's SEC filings and included in our most recent annual report on Form 10-K and quarterly reports on Form 10-Q. Undue reliance should not be placed on forward-looking statements, which speak only as of the date they are made and as facts and circumstances underlying these forward-looking statements may change. Except as required by law, aTyr Pharma disclaims any obligation to update these forward-looking statements to reflect future information, events or circumstances. I will now turn the call over to Sanjay.

Thank you, Jill and good afternoon, everyone. During the fourth quarter of 2018, we took a significant step forward in the development of our lead therapeutic candidate, ATYR1923. In October, we announced the selection of pulmonary sarcoidosis as the first disease indication for clinical development of 1923. We believe that by modulating the activity of key immune cells involved in this disease, 1923 has the potential to down-regulate inflammation in pulmonary sarcoidosis patients, thereby preventing further clinical morbidity and progression of disease. In December, we initiated a Phase Ib/IIa clinical trial evaluating 1923 for the treatment of pulmonary sarcoidosis. Importantly, we are running this trial in collaboration with the Foundation for Sarcoidosis Research and its Clinical Studies Network, which is providing critical assistance with trial site initiation and patient recruitment. This collaboration will promote the efficient execution of this important first-in-patient study. We are currently in the process of patient enrollment and are bringing trial sites online. As a reminder, this study is a multiple ascending dose, placebo controlled, first-in-patient study of ATYR1923 that has been designed to evaluate the safety, tolerability, steroid-sparing effect, immunogenicity, and PK of multiple doses of 1923 as well as to evaluate established clinical endpoints and potential biomarkers to assess preliminary efficacy. 36 patients will be enrolled into three staggered multiple dose cohorts at doses of 1, 3, and 5 milligrams per kilogram and randomized two to one to receive either 1923 or placebo. These are the top three doses that we evaluated in our single ascending dose Phase I study and we believe each of these doses have therapeutic potential based on our translational efficacy data. Study drug will be administered by IV every four weeks for a total of six doses. Follow-up visits are planned for approximately four weeks following the last infusion.…

Thank you, Sanjay. Research and development expenses were 3.5 million and 20.4 million for the three and 12-month periods ending December 31, 2018 compared to 5.3 million and 30.1 million for the three and nine-month periods ending December 31, 2017. The decreases were primarily related to the completion of pre-clinical and clinical studies related to ATYR1923 and ATYR1940 in 2017 and related manufacturing expenses along with a decrease in personnel related costs. The decrease was partially offset by an increase in 1.1 million related to the initiation of our ATYR1923 Phase Ib/IIa clinical trial. General and administrative expenses were 2.4 million and 12.4 million for the three and 12-month periods ended December 31, 2018 compared to 5.9 million and 17.1 million for the three and nine-month periods ending December 31, 2017. The decreases were primarily related to a reduction in personnel related costs and professional fees. As we mentioned in our last earnings call, net of our debt payments, we entered this year burning approximately 10 million per quarter in Q417 and exited the year, burning approximately 6 million per quarter in Q418. Our cash burn is in line with our expectations and I’m very pleased with our reduction in operating expenses. As of December 31, 2018, we had 49.5 million in cash, cash equivalents and investments. Our net cash position was approximately 33.5 million as of December 31, 2018. Our total net cash position includes approximately 16 million in debt from our loan facility. Looking forward to 2019, we believe our cash burn will continue to stay steady with an anticipated burn of 23 million to 25 million, net of debt. Now, I'd like to turn the call back over to Sanjay before we open it up to Q&A.

Thanks, Jill. So in closing, during 2018, we made notable progress on a number of fronts, both clinically and operationally and we enter 2019 with significant momentum. We are fast approaching an inflection point for our Company later this year with interim results from our ongoing proof-of-concept Phase Ib/IIa trial of ATYR1923, which, if positive, will usher in a new era for our Company. We appreciate your interest and continued support. At this time, Jill and I will be happy to take your questions.

[Operator Instructions] And our first question is from Joel Beatty with Citi.

Good afternoon. This is Shawn Egan calling in for Joel. Thank you for taking my questions. Could you maybe frame your expectations for success for your interim look in 4Q? I know that you'll be looking at a number of meaningful endpoints for this indication such as like FVC and PET, skin lesions and steroid utilization. Are any of these more meaningful than others in your view and what type of signals would give you confidence going forward?

Great. Thanks, Shawn. Nice to talk to you again. I think what we'll be looking for in Q4 is, of course, kind of an interim look on where we are, and from a starting point, this is a safety and tolerability study, first and foremost. So I think those initial clues around how the safety of 1923 is holding up, in particular in a multiple ascending dose trial, will be important for us to talk about. You highlighted a number of efficacy endpoints that we're looking at. I think one of the things we're really keen to determine here is whether or not 1923 can have a steroid sparing effect. So I think any kind of initial trends that we see improvement of steroid utilization in particular in those early cohorts will be important. With some of those other biomarkers and those endpoints that you pointed out, we may need to wait until final study results. PET scans might be an area where depending on the number of patients we enroll at that time, that's another intriguing trend that we could look at. So I think when we think about the fourth quarter, I'll be providing an update a little bit more about what to expect once we get a little bit more into our trial and we approach fourth quarter.

Great. In regards to the steroid sparing effect, could you talk about how the trial is designed? Are both placebo and treated patients going to receive the taper and then just incremental increase in steroid will be given when patient's experience coughing or -- is that roughly how it works?

Correct, Correct. So you've got it there that in the sense that, all patients whether they receive 1923 or placebo are going to be knocked down over the first 50 days of the trial. So they'll be, in essence, made unwell by being put on 5 milligrams, and then we'll be looking for kind of a real-world clinical component here around depending on how folks cough and shortness of breath trend. The clinicians will have to titrate their steroids back up. We believe those patients on 1923 will be much better controlled at those lower doses of steroids rather than the placebo patients, which we know historically will not be able to be managed at that 5 mg dose and will more than likely have to go right back up to their previous pre-entry dose.

Great. That makes a lot of sense. And you mentioned two other indications that you guys might be pursuing in the future CT-ILD and pneumonitis. Are any of the endpoints in the Phase I/IIb kind of more or less -- to have more or less read through to those indications?

Similar endpoints, however, slightly different in the sense that these are interstitial lung diseases that also have a very pro-inflammatory component, but movement with these diseases may require you to look at something like high-res CT, for example, a bit more than PET. You may be looking again at FVC like we are looking in our trial. They may have different biomarkers of interest to follow, and I also think the relative sensitivity of these patients to therapy may require a longer trial, but I do think based on our knowledge and our engagement with the pulmonary experts, they see those two as two very, very strong indications for us to move into after we develop PoC in a pulmonary sarcoidosis population.

[Operator Instructions] And our next question is from Katherine Xu with William Blair.

Sorry, is this for me?

Yes.

Okay. Sorry about that, I was -- I'm sorry about that. So, this is Katherine with William Blair. So, Sanjay, I'm just wondering in fourth quarter, when you talk about the interim analysis, do you think you can get to 24 patients in that time or is it going to be 12? And also for CSL partnership, I wonder what kind of indications and also what synthetases they are? Can you confirm they are not histadyl-tRNA and what indications are potentially contemplated for those programs? Thank you.

Sure, Katherine. Good questions. I'll start from the top there. Regarding the number of patients, I'll look to update the market mid-year to just let folks know whether it's closer to 12 patients, 15, I really don't know at this point, but I do think that once we kind of get into the season of the trial and progress a little bit more, I'll have a better handle on the number of patients to expect interim results. Again, that's predicated on enrollment over the first half of this year. So I'm going to come back to you on that probably next quarter. With regard to the CSL collaboration, number one, I'll confirm, it does not include histidyl-tRNA synthetase. We haven't disclosed the four tRNA synthetases that we'll be working on, but I can confirm here it's not HARS, HARS is not one of them of these four, these are four different opportunities. When you talk about where this can go and what indications, it's a little bit early, but I will tell you that CSL's kind of goal and how they've sort of reframed their company, as a company that was really known to be more of a plasma therapeutics leader, now they're really looking more in areas of immunology, hematology, neuroscience, and neurology. So as you can imagine, these are areas that we believe that should we follow up on some of the signals that we think are part of this portfolio, that's the kind of areas that we would be looking to target. With regard to specific disease indications, it's a little bit early, but maybe that provides you a little bit of the sort of buckets that aTyr and CSL is thinking about.

Katherine, does that answer your question?

Yes. Thank you very much.

Thank you. And I'm not showing any further questions in the queue. I would like to pass the call back to Sanjay for his final remarks.

Sure. Well, thank you everyone for joining our call this afternoon. We'll look forward to providing you more information at our next quarterly update in May. Thank you again.

Ladies and gentlemen, thank you for participating in today's conference. This concludes the program and you may all disconnect. Have a wonderful day.