Greetings, welcome to Rigel Pharmaceuticals Financial Conference Call for the First Quarter 2022. At this time, all participants are in listen-only mode. A brief question-and-answer session will follow the formal presentation. As a reminder, this conference is being recorded. It is now my pleasure to introduce our first speaker, Dolly Vance, who is Rigel’s Executive Vice President, Corporate Affairs and General Counsel. Thank you. Ms. Vance, you may now begin.

Thank you. Welcome to our first quarter 2022 financial results and business update conference call. The financial press release for the first quarter was issued a short while ago and can be viewed along with the accompanying slides for this presentation in the News & Events section of our Investor Relations site on www.rigel.com. As a reminder, during today’s call, we may make forward-looking statements regarding our financial outlook and our plans and timing for regulatory and product development. 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 Annual Report on Form 10-K for the year ended December 31, 2021 and subsequent filings with the SEC, including our December 31 quarterly report on Form 10-Q on file with the SEC. Any forward-looking statements are made only as of today’s date and we undertake no obligation to update these forward-looking statements to reflect subsequent events or circumstances. At this time, I would like to turn the call over to our President and CEO, Raul Rodriguez. Raul?

Thank you, Dolly, and thank you everyone for joining today. Also with me today are Dave Santos, our Chief Commercial Officer; Dr. Wolfgang Dummer, our Chief Medical Officer; and Dean Schorno, our Chief Financial Officer. Moving on to Slide 5, we are also going to introduce you to Caroline Piatek, M.D. who is joining us on the call today. Dr. Piatek is Associate Professor of Clinical Medicine at the Jane Anne Nohl Division of Hematology at USC's Keck School of Medicine. She has deep expertise in ITP and warm autoimmune hemolytic anemia or warm AIHA. She is also investigator on the FORWARD trial, Rigel's Phase 3 clinical trial in warm AIHA. During this call, Dr. Piatek will discuss the disease state, treatment landscape, and patient journey in warm AIHA. She will also provide critical insights into how she treats warm AIHA patients and her experience in treating patients with ITP with TAVALISSE. Lastly, she will discuss how she views the opportunity for TAVALISSE in warm AIHA. I'd like to thank Dr. Piatek for joining us today and look forward to her perspectives. Beginning on Slide 6, we have made significant progress, growing our commercial hematology oncology organization while executing in several near-term value drivers in our late and mid stage pipeline. Starting with the first value driver, growing ITP sales, during the first quarter, we began to see momentum build for TAVALISSE sales in ITP with the highest quarterly demand since launch. We believe this is a direct result of our commercial initiatives. As you may recall, last year, we undertook a sales force expansion to broaden our reach, improve efficiency, and increase in-person interactions. We also secured preferred status on three major national formularies. We are pleased to see that these initiatives have translated into a positive growth trend…

Thank you, Raul. On Slide 8, you'll see our FDA approved indication, which is for adult patients with chronic immune thrombocytopenia, or cITP, who had an insufficient response to a previous treatment. Moving to Slide 9, Q1 was the second quarter in a row that we achieved a new high in bottles shipped to patients and clinics. Achieving this new high during a quarter when we have declined over the past two years was particularly good to see, especially given the typical Q1 challenges associated with reimbursement and access limitations due to COVID. We view this as a highly positive sign that we are back on a growth trajectory. Our 1836 bottles shipped to patients and clinics represented 15% growth over Q1 last year, and were driven by more new patient starts than any other quarter during COVID. Particularly, as we moved into the latter part of the quarter, we achieved net sales of $16.2 million, a 31% increase over the same quarter last year. Although the increase compared to a year ago was partially driven by the absence of an inventory drawdown, we are pleased with the positive momentum we're seeing in ITP sales. On Slide 10, you'll see how our customer interactions continued to grow above where they were in Q4 despite starting the quarter with major access challenges in Omicron. Our team accelerated our in-person customer interactions in Q1 two more than five times the number of in-person interactions that we did a year earlier. As Omicron faded, and we moved into March, we were able to have more in-person interactions than ever during the past two years, exceeding our previous high in November by more than 25%. Moving forward we expect to see a continued increase in in-person interactions creating even more opportunities for us to positively impact our customers. We believe that these increased interactions were a major driver .

Ladies and gentlemen please standby.

Thank you. Apologies for we were disconnected there momentarily. I'll ask Dave to continue and begin on slide 10 please.

Great, thank you Raul. So on Slide 10, you'll see how our customer interactions continued to grow above where they were in Q4, despite starting the quarter with major access challenges due to Omicron. Our team accelerated our in-person customer interactions in Q1 to more than five times the number of in-person interactions that we did a year earlier. As Omicron faded, and we moved into March, we were able to have more in-person interactions than ever during the past two years, exceeding our previous high in November by more than 25%. So moving forward, we expect to see a continued increase in in-person interactions, creating more opportunities for us to positively impact our customers. We believe these increased interactions were a major driver of our growing new patient starts in the latter part of Q1, and we are optimistic that the trend will continue to grow as we move through Q2. Additionally, our in-person speaker programs have continued to be an important part of spreading TAVALISSE awareness and education and we executed significantly more programs in Q1 of this year than we did in Q1 of last year. And lastly, on Slide 11, we have several additional initiatives to expand awareness of TAVALISSE and access for patients this quarter. In June we'll attend our first live ASCO meeting since 2019. We will have solid commercial and medical affairs presence there just as we did at ASH in December, and we are planning many activities to interact with customers throughout the meeting. Additionally, in our efforts to expand our patient access globally, our partner Kissei recently submitted an NDA for fostamatinib in ITP to Japan's PMDA. And lastly, in the first quarter, we continued to improve access for commercial patients in the U.S. TAVALISSE is now preferred on the National…

Thank you for that overview, Dave. I'd like to reiterate our excitement as we are getting close to top line results from our pivotal Phase 3 FORWARD trial TAVALISSE in AIHA. I will remind you of TAVALISSE's targeted mechanism of action, our Phase 2 clinical trial results and the design of the FORWARD trial on the next few slides. Slide 17 pretty much explains how and why TAVALISSE should work in AIHA. Very similar to ITP, in AIHA the human body begins to produce auto antibodies that bind to components of the red blood cells. The constant region of those antibodies for the FC region then binds to cells that carry FC receptors, for example, macrophages. The intracellular signaling downstream from the FC receptor is SYK dependent and leads to phagocytosis and destruction of the antibody bearing red blood cells. Some of the destroyed red blood cell antigens are presented to CD4+ T helper cells, which in turn again prime more B cells to making more antibodies, thus perpetuating the disease further, this B cell activation and differentiation process also immediately basic and inhibited by fostamatinib. Taken together, there is compelling scientific rationale to expect that fostamatinib works in AIHA and should not lead to broad immunosuppression, as immunosuppression is not an issue in the life safety database of almost 5000 patients treated with TAVALISSE. Slide 18. In this first clinical data set, we evaluated TAVALISSE in adult patients with warm AIHA in a Phase 2 study. 11 of 24 patients, 46% achieved the hemoglobin level greater than 10 in an increase from baseline of greater than plus 2 gm/dL by week 24. We saw substantial increases in median multibeam levels, detected as early as week two and sustained over time. The safety profile was favorable and consistent with the…

Thank you. I would mention that while achieving a statistical significance with a primary endpoint is a regulatory bar for success, it's really the totality of the data that will provide physicians with the full picture of which patients will derive meaningful benefit from the therapy. I would like to point out the significance of the secondary endpoints and improvement in hemoglobin defined in the secondary endpoints and no need for rescue therapies are clinically meaningful. Improved hemoglobin values in this disease mean our patients feel better, need less frequent monitoring, less use of rescue medications or transfusions, and less frequent hospitalization. Next slide. Okay, so let's talk some more about wAIHA. There are approximately 36,000 adults with wAIHA in the U.S. with approximately 9000 receiving first line treatment. There are about 14,300 patients requiring second or later lines of treatment. Similar to ITP patients are cycling on and off of treatments and we'll discuss more about this in a few moments. wAIHA is an autoimmune disorder characterized by low hemoglobin levels, and laboratory evidence of hemolysis. The severity of symptoms is related to the degree of anemia and includes fatigue, severe weakness, dyspnea, jaundice, splenomegaly, palpitations and other cardiovascular complications. There's an increased risk of thromboembolic events with an incidence of TEE highest early after diagnosis and more common in patients with severe hemolysis. The mortality rate is reported at 8% to 11%, which is related to vascular events including pulmonary embolism, myocardial infarction, stroke, as well as infection or sepsis related to wAIHA treatments. Based on this description, you can see that these are our sick patients. For ITP we often manage relapses in the outpatient setting. However, wAIHA patients often require hospitalization and diagnosis as well as relapse, and it can take days to potentially several weeks…

Thank you Dr. Piatek. Shifting gears now to a quick update on our ITP program. Moving to Slide 28, we continue to believe that fostamatinib can provide therapeutic benefit in COVID-19. There are several scientific pieces of external research at independent institutions. Most importantly, last year, we reported positive clinical data from the NIH NHLBI Phase 2 study in hospitalized patients with severe COVID. That data was published last fall. Additional data will be presented by collaborators at this year's ATS Conference in May. Given persistent resistance to vaccination in some places, and the possibility of new virus variants, we believe a need for effective treatment options for severely ill patients remains. We have two ongoing Phase 3 studies that will provide us with pivotal data, and if approved in this indication, TAVALISSE will be available for immediate use for these patients. Slide 29. Before I discuss our pivotal Phase 3 study, I would like to provide an update on two other trials from collaborators. For MATIS Phase 2 at the Imperial College of London and the ACTIV-4 host tissue Phase 3 study from NIH. Regarding MATIS, an independent data review board recommended not to continue fostamatinib into the second phase of the trials. That recommendation was not due to any safety concern. The focus of the study was the prevention of progression of mild to severe disease. Regarding the NIH ACTIV-4 study, an interim analysis was run on two of the three experimental drug arms of the study, and enrollment was discontinued for both. So fostamatinib is now the only remaining active arm on the study and continues to enroll patients. Rigel's own amended Phase 3 trial is also continuing. As mentioned earlier this year, we updated the inclusion criteria for the trial to focus on more severe patients…

Thank you, Wolfgang. I'm on Slide 36. For the first quarter of 2022, we shipped 1824 bottles for specialty distributors, resulting in $22.6 million of gross product sales. 1836 of those bottles were shipped to patients at clinics, while 925 bottles were made in our distribution channels at the end of the quarter. We reported net product sales and top lease of $16.2 million, a 31% increase compared to the same period in 2021. Our net product sales in TAVALISSE were accorded net investment discounts, charge backs, rebates, returns, copay assistance and other allowances of $6.4 million. Our gross to net adjustment is approximately 28.4% of gross product sales for the first quarter of 2022. Before we move on to net product sales, let me review our expectations for the second quarter of 2022. We're pleased with the strength of our bottles shipped to patients or clinics at the end of the first quarter that Dave described, and expect growth to continue as access to physicians and new patient starts continues to expand. Incrementally, we currently expect our gross to net adjustments to be approximately 30% in the second quarter of 2022. We don't typically comment on potential collaboration milestone payments due to payment variability and uncertainty. We wanted to provide a brief financial update as it relates to Kissei's NDA filing in Japan that Raul highlighted. With this filing we expect to receive a $5 million milestone in the current quarter. If approved, we would expect to receive an incremental $20 million milestone in the first quarter of 2023. We'll continue to provide updates on Kissei's progress of this important filing. On to the next slide, in addition to net product sales, Rigel's contract revenues from collaborations were $500,000 for the three months ended March 31, 2022, which consisted of $200,000 from our license agreement with Lilly and $300,000 from our collaboration agreement with Grifols. Moving on to costs and expenses, our cost of product sales was approximately $121,000 for the first quarter of 2022. Total costs and expenses were $43 million in the first quarter of 2022 versus $39.3 million in the first quarter of 2021. The increase in costs and expenses was primarily due to increased commercial activities related to the sales force expansion in late 2021, increased research and development costs for the development of Rigel's RAK1/4 inhibitor program, and increased personnel related costs and stock based compensation expense, partially offset by decreased research and development costs related to our Phase 3 clinical trial of fostamatinib for warm autoimmune hemolytic anemia, and our ongoing Phase 3 clinical trial of fostamatinib in hospitalized patients with COVID-19. Finally, we ended the quarter with cash, cash equivalents and short-term investments of $107.5 million. With that, I'd like to turn the call back over to Raul.

Thank you, Dean. Rigel's performance in the first quarter has given us a strong start to the year and we will continue to execute on our strategic priorities as you see here. Looking forward, we expect the momentum that we were seeing in the commercial front to continue into the upcoming quarters, facilitating ITP sales growth. Most importantly is our upcoming Phase 3 trial readout in warm AIHA. We're excited about this readout because it is a key step in building our hemolytic portfolio. Warm AIHA is complementary to our current commercial focus, and so will be highly synergistic and accretive. It will be great to be able to deliver a new and helpful medicine for the first time to patients suffering from warm AIHA and to do so as early as 2023. Now let's open the call to your questions and given that Dr. Piatek is with us, let's prioritize warm AIHA related questions. Operator?

Thank you. Thank you. Our first question is from the line of Eun Yang with Jefferies. Please proceed with your questions.

Thank you. I have one question to Dr. Piatek. So in Phase 3 for the trial, if I remember it correctly, patients who have actively hemolysis and also they are on some background therapy. So with the entry criteria what do you expect the placebo response to be according to Phase 3 primary endpoint?

Thank you, Eun. Dr. Piatek?

I'd like Wolfgang on this as well. But I would anticipate there would be a low response rate for placebo. And the correlate here is that in the Phase 2 data the non-responders did not achieve a hemoglobin response. So kind of using that here, we would anticipate a low response rate than the placebo for the Phase 3.

Yes, I would agree with that. We do not see patients generally just bounce up and down two units. That's a pretty large jump up from any baseline and to stay up there for three consecutive visits would be very surprising unless the patient is on an effective therapy.

Okay, and I have a question to the company. So in Phase 2, I think about 38% of patients were second line and the remainder of the patients were third or fourth line level line of therapies. And although the overall response rate was over 40, around 45% I think there was a higher response in second line patients. So my question to the company is that, in terms of baseline patient characteristics by the line of therapy in Phase 3 is it kind of similar to Phase 2?

I'll ask Wolfgang to comment.

Yes. So in general, I would say we've had probably somewhat more patients in earlier lines, because as you are aware, we are conducting this trial in the United States, but also in a number of countries in Europe, including Eastern Europe, where compounds such Rituxan for example, are a little bit less used or available. So in general, it's most likely a similar patient population, but maybe somewhat earlier line. And we do expect certainly comparable or even slightly better data from Phase 3 than what we have seen in Phase 2.

Thank you.

Our next question is from the line of Yigal Nochomovitz of Citi. ego, Please proceed with your questions.

Hi, this is Carly on for Yigal. Thanks for taking our questions. We have one for Dr. Piatek. We're wondering how the 46% response rate and the 29% durable responder rate seen in the Phase 2 study compared to experience with rituximab and other therapies currently used post steroids? And I guess if the Phase 2 data are largely replicated in the Phase 3, could you go into a bit more detail on how you would think about using TAVALISSE in your practice in terms of line of therapy? Thank you.

Thank you, Carly. Dr. Piatek?

So I mean, I think if TAVALISSE is approved, it would be the only approved medication for this indication. In the third line setting, there's a clear role. In the second line setting it would also be a reasonable choice. And I would like to see within the baseline demographics for the Phase 3, we see a lot of patients who had not received prior rituximab. So it would be beneficial to see the data there to see which -- how these patients benefit. But our anticipation similar to the ITP data is that the earlier on use TAVALISSE the higher the efficacy would be suggesting our role in the second line setting.

All right and Wolfgang of you can comment.

Yes, I would just add to that and we've sort of elaborated a little bit on this I think. The primary endpoints that was required by regulatory agencies is a very high bar. But we have a number of secondary endpoints that also capture clinical benefits. So we really think there's a substantial percentage of patients that can have clinical benefit. And it's going to be the totality of the data and Dr. Piatek will confirm that the totality of the data that will make a treatment decision and also in collaboration with the patient, a patient might want to have an oral drug over an infusion or vice versa. So I think we are well positioned to play an important role there. The last comment that I want to make is when you refer to other compounds, such as Rituxan, and if you want to make comparisons, you're free to do so, but you will need to be very, very stringent in really understanding what the endpoints are and how it's not apples to apples when you talk about overall response rates versus our primary endpoint, that's not comparable. So I believe we can certainly come out in a similar ballpark.

Okay, got it. That's, that's really helpful. And then just one sort of housekeeping question for the company. Are you able to refine the timing guidance at all for the forward data from midyear to maybe around which month this summer we could expect to see the data? Thanks so much again.

I can clarify that. I think, you know, we could tell you that it's going to be in June, to be more specific, not more specific than that though.

Okay, great. Thanks for your time.

So it's in the upcoming month.

Our next question comes from the line of Gary Nachman with BMO Capital Markets. Please proceed with your questions.

Hi. For Dr. Piatek first, when you see TAVALISSE fitting into the treatment paradigm for warm AIHA, will there be a lot of combination use with this product? And do you envision any challenges in terms of access with that? And what would it take for the product to potentially be a first line drug? Is that even a possibility over time?

Hi, thank you. I'll ask Dr. Piatek to comment, but also Dave comment because we've done some market research in that area. Go ahead.

So we don't have any data to conform on combination use. You know, the clinical trials do have washout periods and time for stability on steroids. So the potential is that it would be overlapped more closely with steroids with the effort for it to be a steroid-sparing agent. We do not have any data in the first line setting. There is a role for steroids in wAIHA just as ITP. So I -- it's hard to go beyond that.

Thank you. Dave?

Yes, Gary. One thing I would like to mention here is that it depends on where patients are relapsing. If they are in an acute setting in the hospital, sometimes it's very difficult, as we've learned from recent market research for clinicians to prescribe Rituxan and administer it in the inpatient setting. So they have to wait for the patient to be discharged and use it the outpatient setting. It's not everywhere, but certainly in the community that is happening. And so you think about a drug like fostamatinib, which could be used, starting in the inpatient setting patient takes it and moves it into the outpatient setting. And then because of its potentially rapid risk response, the ability then to taper steroids and that that appears to be very interesting to clinicians as we talk to them now.

And you saw in the slide that Dave provided earlier, there's substantial mixing and matching, including in first line therapies with AIHA. It's a little bit different than ITP in that regard.

Yes. Okay, that's helpful. And then I guess, for both Dr. Piatek and the company, for the 14.3 thousand and addressable patients in second line plus, how many of these are easy to tap into? And will there be challenges getting to any of these patients to get treated in the later lines or are they readily available for the most part, I'm curious, how much of an effort is required to increase awareness for wAIHA? Or, is it well known, then the clinicians are treating most of these patients already? Thanks,

Thank you, Gary. I'll ask Dave to comment first and then Dr. Piatek if you would like to as well.

Yes and so what I would say, Gary is just, it is 14,000 patients out there who are actively undergoing treatment every year. But it will require us to reach a broad number of physicians because, particularly in the community, it's pretty evident that clinicians see a handful of these patients over time, and they manage them and some are beyond treatment and some won't. So I think they're aware of patients that are out there. They know that if they do relapse, that they're going to need to treat them. But we will have to reach a large number of prescribers in order to get that awareness out there.

Keep in mind on that point before I ask Dr. Piatek to comment also is that it is not unlike ITP, where it's a rare disease of hematology, but not hematology and these doctors see a small number of these patients. When you add these two indications together, it becomes a much more substantial patient population within that doctor visit. As I said, substantial, almost complete overlap in the doctors who treat both of these indications. So it's something that we're knowledgeable of and experienced in handling. Dr. Piatek, anything to add beyond that?

I think that fairly covered everything that I would have said. I would just add that the multiple refractory patients often get referred to an academic center and in that setting then perhaps not net worth probably have a higher awareness.

Okay, great. Thank you.

The next question is coming from the line of Do Kim with Piper Sandler. Please proceed with your questions.

Hi, everyone, this is EK on for Do. Thanks for taking the question and congrats on the continued progress. For Dr. Piatek just a quick one, I don’t know if I might have missed it, but if you can speak on your belief of the receptivity of your colleagues and yourselves of TAVALISSE and warm AIHA, as I say, given the current dynamics of how you're treating patients and the relapse rate, there is a kind of entrenchment of sorts with current therapies and your colleagues are looking for something novel or you know, just your brief thoughts on it would be helpful for us.

Sure, so I would say that there is definitely a clinical need for targeted therapies in this disease. You can see from some of the cases we discussed that, especially in those multiple refractory patients, we really just don't know how to treat these patients and leads to that cycling through therapies with unclear efficacy. So it's kind of, it's challenging for the patients as well as the physicians to treat these types of patients. During the COVID times, we found that preference towards oral therapies, keeping our patients out of the infusion centers when possible, and a patient preference for oral treatments. So I think there definitely is a need and the targeted mechanism of action is compelling and is of interest to treating physicians.

Okay, great. So, sorry. So just a quick followup on available treatments or emerging treatments, I don't know if you have any experience with some of the different therapies that are coming down the pipe, such as like FcRn antagonists. If you are out and if you can kind of speak to what you think about the mechanisms of action for those therapies compared to TAVALISSE?

Dr. Piatek?

Sure, so I think what we're seeing is that this is a heterogeneous disease, and some patients may respond to some therapy versus another. I think it's clear that we're moving to an era of targeted therapy in this disease, but to really to contrast the different mechanisms is a little bit beyond the data that we have right now.

Yes, let me too add on is that many of these doctors and the objective for us is to have the doctors that are already using TAVALISSE for ITP. So they already know the product, they know its mechanism, they have some experience with it. And I think that will help the receptivity for a new indication AIHA, where there's even less available treatments for that indication. So I think that should help in terms of the receptivity. In part, the reason we've expanded the commercial organization last year, is to raise that awareness for TAVALISSE in ITP, so as to facilitate the receptivity for AIHA.

Okay, great, thanks for that. I have just one last question for Dean, can you tell us what happened with the non-recognition of the government revenues? I believe that's $6 million just left within those contracts and didn't see anything in the Q, is there any correlation with the timelines of the current your COVID sponsored trial or is it completely distinct from that?

Yes, thanks EK for the question. So just to remind everyone, we have a 16.5 million overall grant from the DOD, which is supportive of our Phase 3 study in COVID, which largely pays for the costs or external costs of that study. To date, we've recognized $10 million of revenue, and collected $10 million of cash. That contract specifies that over the course of the study, there are certain milestones that we get paid for and therefore, as you point out, EK, we've got $6.5 million, $6 million remaining of that $16.5 million we will incur during the future of this study, or we'll recognize the revenue and collect the cash over the course of the remainder of the study. So stay tuned, that will come out in future quarters, but there was no recognition, no milestone in Q1 as you highlight.

That sounds good. Thanks everyone.

Thank you.

The next question is coming from the line of Kalpit Patel from B. Riley. Please proceed with your questions.

Yes. Hi, thanks for taking my questions. I'll start with Dr. Piatek. For the Phase 3 trial, what is the delta that you're looking for between the active arm and the placebo arm that would be clinically meaningful in your view? I mean, is there a percentage like 20% or 30% that you would view as impressive in addition to hitting stat sig? And then I have a follow up.

Dr. Piatek do you have a comment?

There isn't a specific delta that I'm looking for in the Phase 3. What I'm interested in is, is seeing that there's a clear group of responders with durable responses. And in trying to parse out which patients derive benefit from fostamatinib and kind of sorting out those characteristics. And again, kind of highlighting that from secondary endpoints, a number of them are clinically meaningful in clinical practice.

Okay, fair enough. And then I know the protocol allows the use of rescue therapies, but the patients that received the rescue therapies, they won't be counted as a responder if it's received within a certain time period. So I guess my question for you doctor is that, if you were to receive an RBC transfusion, how long is that hemoglobin improvement good for in the real world?

So the red blood cells that these patients are transfused are also hemolyzed. So it would -- it varies a little bit, but it could be, you can see no response to maybe a response that lasts for several days, but it does not last the same duration as somebody who is transfused for another reason without hemolysis.

Okay, and that reminds you of, I just want to remind you that you have to be off of that acute therapy for at least four weeks of adoption, before you can start counting as a responder if that's clear. So like a response for a few days or even a couple of weeks of the transfusion is very unlikely making a durable responder possible.

Okay, and then one question for the company. Now, that you have three years of experience launching TAVALISSE, do you have any metrics on the median duration of treatment with real world patients? And then if you can also break down the new starts versus continued treatment in your sales metric for the latest quarter, that would be useful?

Thanks, so let's Dave to comment. I'm not sure that we provided the latter as yet, so maybe you can comment on the first how long the longevity perhaps of patients on ITP Dave?

Yes, so currently we have in the mid 50s is our persistency rate, which we've maintained for quite a while for patients at four months of therapy. So generally about five bottles is what you would say that most patients would get on therapy, if you averaged it out over all the patients. And all I would say is, when we saw this growth in Q1, it was clearly that we were putting more patients in the top of the funnel than we were actually that patients were going out at the bottom of the funnel and saying we're coming off drugs. So I -- although we're not telling you the percent of our business that is new patients right now, it's a growing percentage.

As you saw, good increase in new patient starts which I think bodes really well for future quarters as we see that entering. So we're excited about having achieved that in Q1, which is really a good place to start the year.

Okay, that's very helpful. Thank you.

Thank you.

The next question is coming from the line of Joeph Pantginis with H.C. Wainwright. Please proceed with your questions.

Hi everybody, good afternoon. Thanks for taking the question. Just wanted to ask Dr. Piatek the sort of a combination of the questions that's been asked and also Raul made a comment earlier about a lot of the same treating physicians that used to have a lease now will also look to potentially dose TAVALISSE for these patients. So I want to look at it of how you look at the evolution of the market, and you did touch upon it in certain ways. But the way I want to approach it is, if you look at the Slide 14, now this is the one that has the different bar graphs for the different lines of treatment and how heterogeneous it is. The numbers might be different, obviously, but the typical view of this chart is virtually identical to what is seen in ITP, with multiple approved therapies, and it took quite some time to be able to have the ITP community agree on different treatment guidelines. So even though TAVALISSE might be the first approved drug, which could gain obviously, good traction, presumably, do you see the heterogeneity still remaining for a while?

Okay, thanks for the question Joe. I'll ask Dave to comment and I'll add a comment afterwards.

Yes I can just say that and we're currently conducting market research almost on a daily basis at this point, talking to clinicians, and they are very interested in having something that they can use in this disease. It's not even though it has similarities to ITP. It is, it concerns them more. And sometimes these patients can get into a lot of trouble. And so they want to have new options. And so I think there's going to be a lot of very willing people to listen to the message that we're going to bring is we're shaping that message now to clinicians, when if we do have approval, and I think it's going to be very solid add to their armamentarium, which is probably a little bit different than an ITP where they had depots existing for quite a while. And probably the unmet need was not nearly as high.

But maybe a somewhat similar to the ITP market pre- exactly the place to start. And you saw how the market evolved there with the getting a predominant or very substantial share of the ITP market over the course of years. So if we could achieve anything nearly that we'd be tremendously happy.

That's definitely a good analogy. Yep.

Thank you, Joe.

Next question is from the line of Bert Hazlett with BTIG. Please proceed with your questions.

Thank you. And thank you for taking the question. But it's for Dr. Piatek. And as we consider the Phase 3 data upcoming, you'd mentioned during your initial comments, it focused on the secondary endpoints is being material as well. I'd love for you to elaborate just a bit with regard to what might be important and significant out of the secondary endpoints that we've seen previously, the rapidity response, the magnitude, or even the use of rescue meds, but a little elaboration there would be helpful? And thank you for taking the question.

Yes, sure Dr. Piatek.

Sure, so I think the secondary endpoints are a little bit inner woven. So basically, meaning that if you're seeing these hemoglobin responses, this in turn leads to less need of rescue medication. So if you're roughly thinking of hemoglobin of 7 as the usual transfusion threshold, basically at the threshold of where people are starting to feel bad. If we're getting people up closer, well above that transfusion threshold that's clinically meaningful. And improvement from baseline means, less intensive therapy, less potential need for transfusion. So what we're trying to do is kind of get our patients out of the hospital and feeling like they can do their activities of daily living or if not more than that. So the farther we can get from these numbers around 7, the better and for longer periods of time.

Thank you for that. Thank you, Bert.

Thank you. There are no further questions at this time and I'd like to turn the floor back to Mr. Raul Rodriguez for closing comments.

Thank you, and thank you, everyone for joining and for your questions on this and your continued interest in Rigel. In addition, I'd like to thank Dr. Piatek for joining us on the call and giving us her thoughts on warm autoimmune hemolytic anemia and TAVALISSE. I very much appreciate it and very helpful to all of us. As you know, we've made great progress this past quarter and we have exciting milestones coming most importantly our Phase 3 milestone in AIHA in the very near term as you know. I'd also like to thank our employees for their consistent constant commitment to improving the lives of these patients. Thank you. We look forward to updating you on our progress in future calls. Have a great day.

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