Harmony Biosciences (HRMY) Q4 2022 Earnings Call Transcript

Harmony Biosciences (HRMY -0.17%)
Q4 2022 Earnings Call
Feb 21, 2023, 8:30 a.m. ET

Contents:

• Prepared Remarks
• Questions and Answers
• Call Participants

Prepared Remarks:

Operator

Good morning, everyone. My name is Todd, and I will be your conference operator today. At this time, I would like to welcome everyone to Harmony Biosciences' fourth-quarter and full-year 2022 financial results conference call. All participants have been placed on mute to prevent any background noise.

After the speakers' remarks, there will be a question-and-answer session. [Operator instructions] Please be advised that today's conference may be recorded. [Operator instructions] I will now turn the call over to Luis Sanay, head of investor relations. Please go ahead.

Luis Sanay -- Head of Investor Relations

Thank you, operator. Good morning, everyone, and thank you for joining us today as we review Harmony Biosciences' fourth-quarter and full-year 2022 financial results and provide a business update. Before we start, I encourage everyone to go to the Investors section of our website to find the materials that accompany our discussion today, including a reconciliation of our GAAP to non-GAAP financial measures. At this stage of our life cycle, we believe non-GAAP financial results better represent the underlying business performance.

Our presenters on today's call are; Dr. Jeffrey Dayno, interm CEO and chief medical officer; Jeffrey Dierks, chief commercial officer; and Sandip Kapadia, chief financial officer. Moving on to Slide 2. As a reminder, we will be making forward-looking statements today which are based on our current expectations and beliefs.

These statements are subject to certain risks and uncertainties. Our actual results may differ materially, and we undertake no obligation to update these statements even if circumstances change. We encourage you to consult the risk factors referenced in our SEC filings for additional details. I would now like to turn the call over to Dr.

Jeffrey Dayno. Jeff?

Jeff Dayno -- Chief Medical Officer and Interim Chief Executive Officer

Thank you, Luis, and thank you, everyone, for joining our conference call today. We delivered another strong quarter in Q4, finishing the year with continued momentum in our commercial business for WAKIX, as well as in the advancement of our clinical development programs for pitolisant. We are excited for 2023 and remain confident in the ongoing execution of our three-pillar growth strategy to further evolve Harmony into a leading rare disease company focused on delivering innovative therapies for patients living with rare neurological diseases. Harmony remains a growth story with a focus on advancement of our life cycle management programs for pitolisant and acquisition of new assets to build out our pipeline to drive additional growth.

With that as our focus, I am excited to lead the company forward. After 12 years as a practicing neurologist taking care of patients, followed by 25 years in the industry touching every aspect of the business, I bring a unique perspective to the development and commercialization of innovative treatments that address major unmet medical needs. I have seen the impact that these treatments can have on patients and their families, and I'm proud of the progress we've made. I also know that Harmony is poised for continued growth with our goal to help even more patients living with rare neurological diseases.

I will now briefly highlight our progress on each of the three pillars of our growth strategy in the context of Q4 2022 performance. Starting with pillar one, which is to optimize the commercial performance of WAKIX. We delivered WAKIX net revenue for the fourth-quarter and full-year 2022 of 128.3 million and 437.9 million respectively representing an increase of 41% and 43% year over year. Our performance reflects the strong commercial execution by our team, the underlying demand for WAKIX, and the significant unmet need that remains in the narcolepsy market.

For 2023, we expect continued growth for WAKIX and believe that the vast market opportunity, which remains in narcolepsy, along with a differentiated product profile of WAKIX, provides us with the ability to grow wake up for years to come. At Harmony, this also translates into an opportunity to help even more adult patients living with narcolepsy. Moving to pillar two, which is to expand the clinical utility of pitolisant beyond narcolepsy. We are extremely pleased with the progress that we've made across all our pipelines and life cycle management programs, and I will provide more details on these during the clinical update later in the call.

Briefly, in idiopathic hypersomnia, or IH, we continue to see strong momentum in our Phase 3 INTUNE study. This opportunity, if successful, could be the next potential new indication for pitolisant. In Prader-Willi syndrome, or PWS, we are analyzing the full data set from our Phase 2 proof-of-concept study in preparation for an end-of-Phase 2 meeting with the FDA. It is our intent to advance the PWS program to a Phase 3 trial.

Overall, our life cycle management programs for pitolisant in total could address unmet medical needs and up to 100,000 diagnosed patients living with IH, PWS, and myotonic dystrophy. An opportunity that is successful would more than double our diagnosed-patient opportunity. We are committed to advancing these development programs and are hopeful that these efforts could lead to additional new indications for pitolisant and address the unmet medical needs in these patient populations. And finally, pillar three, acquiring new assets through business development to expand our portfolio beyond WAKIX.

Our dedicated business development team has been actively assessing the landscape as it is our intent to build out a broad pipeline of rare orphan neurology assets and our assets in other neurological diseases where we can leverage our existing expertise and infrastructure. To achieve this, we intend to leverage our strong financial position to acquire additional assets across a range of development stages, including both early and later stage, with the potential to launch both during and after the WAKIX life cycle. We are in a solid position to execute on pillar three as our business fundamentals with WAKIX remain strong, and we ended the year with approximately 346 million in cash, cash equivalents, and investment securities. Overall, I'm extremely pleased with the progress that our team has made on our three-pillar growth strategy.

We remain very confident in WAKIX being a potential $1 billion plus franchise in the coming years by our narcolepsy and additional indications and are truly excited for 2023, during which, our team will remain focused on executional excellence. I will now turn the call over to Jeffrey Dierks, our chief commercial officer, to provide more details on our commercial performance. Jeff?

Jeff Dierks -- Chief Commercial Officer

Thanks, Jeff. Q4 represented another strong quarter performance for WAKIX, and 2022 full-year performance demonstrated strong overall growth and momentum in our underlying business fundamentals. Net revenue for the fourth quarter was $128.3 million, representing a 41% increase from the same quarter prior year. Full-year 2022 net revenue was $437.9 million, which representative 43% increase from full year 2021.

Our strong performance reflects not only the resilience and commitment of our team, but also speaks to the strong underlying demand for WAKIX. I'd like to take a moment to highlight a few of our underlying business fundamentals on Slide 5 that drove our performance in the fourth quarter of 2022. The average number of patients on WAKIX increased to approximately 4,900 in the fourth quarter of 2022. The growth in Q4 continues to reflect how the meaningfully differentiated product profile aligns to the unmet needs in the narcolepsy market.

Growth in the average number of patients on WAKIX was driven by the following factors. Harmony field sales and person engagement with healthcare professionals in their office staff remain strong in the fourth quarter. Approximately 85% of all Harmony field sales engagement with healthcare professionals in their office staff were in-person in the fourth quarter. The accessibility of our field sales team with healthcare professionals in their office staff allowed for further education and engagement, helping to drive growth in the depth and breadth of the WAKIX prescriber base.

We saw further growth in the number of new writers of WAKIX, as well as growth in prescribing from existing writers in the fourth quarter of 2022. Growth in new prescribers is driven by both writers and traditional narcolepsy treatments, as well as healthcare professionals who had been reluctant to prescribe other available narcolepsy treatments that are scheduled as controlled substances, including the approximate 1,000 prescribers we added to our call plan earlier in 2022. Existing prescribers of WAKIX continue to find new adult patients with narcolepsy in their practices. Both naive patients, as well as existing patients currently in other treatment with residual symptoms of excessive daytime sleepiness or cataplexy.

The continued growth in both the depth and breadth of our prescriber base demonstrates the broad clinical utility of WAKIX and the broad narcolepsy patient opportunity for the brand. Our performance in Q4 reflects the contribution of our field sales force expansion from earlier in 2022. Our expanded team was able to reach more narcolepsy treating healthcare professionals with greater frequency to educate them on the meaningfully differentiated product profile of WAKIX helping drive the growth that we saw in new and existing writers in Q4. Now, in the third quarter of our expansion, the benefits of our expanded field sales team are now reflected in our base business.

And we're excited about the impact we've seen from our entire award-winning sales team. Looking ahead, we believe there is still a significant opportunity for growth in the years to come for WAKIX and adult narcolepsy, and recent market research commissioned by Harmony reinforces our belief. Research conducted with 70 healthcare professionals with and without experience with WAKIX show that more than 95% of healthcare professionals with WAKIX experience stated they would rate the same or increase prescribing of WAKIX in the next six months and nearly half of those who would not prescribe WAKIX to date stated an intent to prescribe WAKIX in the next six months. We believe our growth will persist as we enter our fourth year of commercialization in this rare orphan-patient population in 2023.

We will continue to tap into the large remaining opportunity in narcolepsy as the market allows around the typical seasonal dynamics at the pharmaceutical industry as a whole experience each year. We expect typical seasonal pair dynamics and normalization of trade inventory in Q1, followed by stronger prescription demand in the second quarter, summer seasonality with fewer patient visits in Q3, and a stronger Q4 as patients look to fill their prescriptions before the end of the year. In summary, we are extremely pleased that the growth in WAKIX, and we believe are strong performance highlights the need for the meaningfully differentiated product profile of WAKIX and affirms our confidence in the future growth opportunity for WAKIX in adult narcolepsy. We continue to believe that WAKIX is a potential billion-dollar plus franchise opportunity in narcolepsy and additional indications and are excited about our ability to help additional adult patients living with narcolepsy and other rare diseases in the future.

I'll now turn the presentation back over to Jeff Dayno for an update on our clinical development programs. Jeff?

Jeff Dayno -- Chief Medical Officer and Interim Chief Executive Officer

Thank you, Jeff. Moving to pillar two of our company growth strategy, to expand the clinical utility of pitolisant toward potential new indications and additional patient populations living with rare neurological diseases as shown on Slide 6, which depicts our development pipeline. Starting with our development program in idiopathic hypersomnia, which we are very excited about. We continue to see strong momentum in our Phase 3 registrational trial in adult patients with IH known as the INTUNE study.

We now have approximately 85% of our clinical trial sites active and patient enrollment is progressing well. If this Phase 3 trial is successful, it could represent the next new indication for WAKIX in adult patients with IH. We plan to provide an enrollment update later in the year. For PWS, as I mentioned in my opening comments, we received a full dataset from our Phase 2 proof-of-concept trial at the end of last year.

As you may recall, last November, we announced that the top-line data showed a positive signal on the primary outcome of excessive daytime sleepiness in this trial. We are currently analyzing the full data set in preparation for an end-of-Phase 2 meeting with the FDA to discuss the trial results. It is our intent to advance the PWS program to a Phase 3 trial, and we will provide an update on our progress later this year. In addition, our plan is to present the findings of the Phase 2 proof-of-concept trial at a future medical meeting and submit the full results for publication to a scientific journal.

Moving on to our development program in myotonic dystrophy, or DM, enrollment continues in our Phase 2 proof-of-concept study in adult patients with type 1 myotonic dystrophy or DM 1. We anticipate top-line data from this phase two proof-of-concept study in the fourth quarter of 2023. Regarding pediatric narcolepsy and a pediatric indication for WAKIX, our partner Bioprojet received a positive opinion from the European Medicines Agency's, or EMA, Committee for Medicinal Products for Human Use, or CHMP, last month with an approval for a pediatric narcolepsy indication expected by the EMA within 60 days of the positive-CHMP opinion. We will now work with Bioprojet on a path forward toward the submission of a supplemental NDA for pediatric narcolepsy to the FDA.

Finally, regarding our efforts in pursuit of pediatric exclusivity, which represents a different regulatory pathway compared to gaining a pediatric indication, we received feedback from the FDA and additional guidance based on that request for a pediatric written request, which we submitted in the third quarter of 2022. Based on this feedback, we will now prepare a proposed pediatric study request and submit it to FDA to gain alignment with the agency in our pursuit of pediatric exclusivity for WAKIX. We will provide an update on our interactions with the FDA later this year. To conclude, we have made significant progress in advancing our clinical development programs with pitolisant and look forward to providing you with further updates later this year.

I also want to take a moment to thank all the patients and their families who are participating in our clinical trials, as well as the clinical investigators for all of their efforts and commitment in helping us to advance our development programs for pitolisant. I will now turn the call over to our CFO, Sandip Kapadia, for an update on our financial performance. Sandip?

Sandip Kapadia -- Chief Financial Officer

Thank you, Jeff. And good morning, everyone. This morning, we issued our fourth-quarter press release and filed our 10-K, where you'll find the details of our fourth-quarter and full-year 2022 financial and operating results. Our financial performance is also shown on Slide 7, Slide 8 and Slide 9.

We finished the year strong and delivered growth across several of our key metrics. We reported strong net revenue growth for the quarter and full year, as well as achieved our second full year of profitability. In addition, we continue to generate cash from operations and remain well positioned to execute on our three-pillar growth strategy. Let me take a moment to take you through our results in detail.

For the fourth quarter of 2022, we reported net revenues of 128.3 million, compared to 91.2 million in the prior-year quarter representing a growth at 41%. On a full-year basis, we delivered net revenues of 437.9 million, a 43% increase over 2021. Our performance reflects the strong underlying demand for WAKIX. In the fourth quarter of 2022, operating expenses were 53.8 million, compared to 44.8 million in the prior quarter, with full-year 2022 operating expenses of 234.2 million.

The higher operating expenses were primarily driven by ongoing commercialization of WAKIX and advancement of our clinical development programs. Operating income improved both on a quarterly and yearly basis. We reported fourth-quarter 2022 operating income of 47.6 million, compared to 28.6 million in the prior-year quarter, representing an increase of 66%. On a full-year basis, operating income was 120.2 million, compared to 87.5 million in 2021, representing a year-over-year increase of 37%.

Non-GAAP adjusted net income for the fourth quarter of 2022 was 61.9 million, or $1.1 per diluted share, compared to 30.4 million, or $0.50 per diluted share, in the prior-year quarter. Non-GAAP adjusted net income for the full year of 2022 was 183.5 million, or $3 per diluted share, reflecting our strong revenue growth and prudent expense management. We believe non-GAAP adjusted net income better reflects the underlying business performance. Please see our press release for a reconciliation of GAAP to non-GAAP results.

During the fourth quarter of 2022, we generated approximately 27 million of cash from operations and ended the year with 345.7 million of cash, cash equivalents, and investment securities. On a full-year basis, we generated approximately 145 million of cash from operations, excluding the $30 million licensing fee part of the 2022 LCA with Bioprojet that was paid in the fourth quarter, cash from operations for the fourth quarter and full year were approximately 57 million and 175 million respectively. Regarding the outlook of our business, we have demonstrated consistent performance for the past three years across several of our key metrics and feel this is sufficient to appropriately model our business. For the full year of 2023, we expect another strong year of revenue growth for WAKIX and remain confident in WAKIX being a potential 1 billion plus franchise in the years to come along with narcolepsy and other indications.

With respect to Q1, we expect the typical industrywide headwinds from higher gross and net deductions and normalization of trade inventories. However, we do expect strong year-over-year net revenue growth for Q1. With respect to expenses, we expect to continue to invest in R&D and SG&A as we advance our clinical development programs and support the strong commercialization of WAKIX. And finally, a comment on our tax rate.

We have used up the majority of our net operating losses, and thus, we expect our go-forward tax rate to be in the mid- to high-20% range. In conclusion, we're very pleased with our strong financial performance, which further strengthens our company profile of growth and profitability, enabling us to execute on our three-pillar growth strategy. And with that, I'd like to turn the call back to Jeff for his closing remarks. Jeff?

Jeff Dayno -- Chief Medical Officer and Interim Chief Executive Officer

Thank you, Sandip. In summary, our strong performance in 2022 positions us well to execute on our strategy. With a strong commercial performance and anticipated future growth of WAKIX in narcolepsy serving as our foundation, we look to our life cycle management programs to drive additional growth for Harmony in the coming years. With active pitolisant development programs in idiopathic hypersomnia, Prader-Willi Syndrome, and Myotonic dystrophy, along with HBS-102, Harmony is poised to extend our value proposition beyond narcolepsy into other rare diseases with diagnosed-patient populations collectively that exceed 100,000 patients, which would more than double our diagnosed-patient opportunity.

Couple this with development programs for our new pitolisant based assets and an opportunity to introduce new treatment options for people living with narcolepsy and potentially other rare neurological diseases, we are excited about the future growth potential for the organization. And we have deep talent across our organization and a solid balance sheet and are effectively positioned to achieve the next level of growth. This concludes our planned remarks for today. Thank you for joining our call.

And I will now turn the call back over to the operator to facilitate the Q&A session. Operator, can you please open the call to questions?

Questions & Answers:

Operator

Yes, sir. [Operator instructions] We'll take our first question from Francois Brisebois with Oppenheimer.

Franc Brisebois -- Oppenheimer and Company -- Analyst

Hi, thanks for taking my questions, and congrats on the quarter. Just a couple of here. I was just wondering, any thoughts going forward? I know we've talked about the growth, the revenue and the commercial opportunity here has been pretty linear. But I was just wondering any thoughts about at this point, it's been launched for a while.

Any thoughts about giving certain guidance?

Jeff Dayno -- Chief Medical Officer and Interim Chief Executive Officer

Good morning, Franc. Thanks for your question. In terms of guidance, so, I think that our underlying business fundamentals remain strong. And as you heard in our remarks for this year, we expect continued growth for WAKIX and believe that the large market opportunity remains in narcolepsy.

And along with the differentiated product profile WAKIX, it provides us the ability to grow the brand for years to come. And with that, I'll ask Sandip to comment a little further around your question.

Sandip Kapadia -- Chief Financial Officer

Thanks, Jeff. You know, Franc, overall, we've demonstrated, as you mentioned, pretty consistent performance over the past three years. And we feel that that's sufficient in terms of at least for modeling purposes going forward. And again, we continue to believe there's a large untapped opportunity.

So, there's certainly growth for many years to come. And I think we're continuing to remain confident in the outlook for WAKIX. We think it's a potential plus franchise in the coming years with narcolepsy and other indications.

Franc Brisebois -- Oppenheimer and Company -- Analyst

OK, thank you very much. And then just on the seasonality of first quarter, I know it's kind of a normal thing in this space that happens. But I think last year, there might have been a little different aspect to it that affected the number of patients added on, not just the gross to net, but on the number of patients may be related to the pandemic. I just wanted to make sure in terms of the outlook, is this something that you would expect again or is this more of a natural gross-to-net kind of impact here?

Jeff Dayno -- Chief Medical Officer and Interim Chief Executive Officer

Yes, sure. Franc. I'm going to ask Jeff Dierks to comment on that question. Go ahead, Jeff.

Jeff Dierks -- Chief Commercial Officer

Good morning, Franc. Yes. So, to answer your question, we do expect to face the same seasonal payer dynamics that you expect to see in Q1 every year. The higher gross, the nets, the higher copay, Medicare out of pocket support, inventory normalization, and the traditional typical prescription reauthorization headwinds.

We did have a couple of one-time events last year, which we do not anticipate this year. As Sandip and Jeff has shared looking into Q1 we do expect year-over-year growth in the quarter and continued growth in the average number of patients for WAKIX and as we interact fourth year of commercialization, as Sandip has shared, we kind of have an anticipated rhythm to our business. We've been able to demonstrate that for the last three years. And we're really excited about the growth opportunity in '23 and for years to come.

And I think our current performance really affirms our long-term growth outlook for the brand.

Franc Brisebois -- Oppenheimer and Company -- Analyst

OK, great. And just I'll cheat here and sneak a quick one here. I just feel like I have to. Any color on the CEO search guidance for a permanent CEO, or is this potentially an interim turning into permanent for Jeff here?

Jeff Dayno -- Chief Medical Officer and Interim Chief Executive Officer

Yeah, Franc. Let me let me respond to that. Thanks for the question. So, obviously, with regards to the CEO position, this is a board decision.

And I won't speak on behalf of the board. And we'll provide an update as appropriate once the board shares their plan on this issue. But that being said, the board has expressed their confidence in myself and the full management team, and we're all focused on the business in hand and executing on our three-pillar growth strategy. And as I've shared, Harmony remains a growth story and our focus on the advancement of our life cycle management programs for pitolisant, acquisition of new assets and business development to build out our pipeline, in addition to our strong underlying business fundamentals of WAKIX in narcolepsy.

So, with that is our focus, I'm well positioned to lead the company forward. And I'm really excited to work with a very talented management team and the broad talent across our organization.

Franc Brisebois -- Oppenheimer and Company -- Analyst

Perfect. Thank you very much. Congrats on the quarter again.

Jeff Dayno -- Chief Medical Officer and Interim Chief Executive Officer

Thanks, Franc.

Operator

Thank you. Our next question comes from David Amsellem with Piper Sandler.

David Amsellem -- Piper Sandler -- Analyst

Hey, thanks, guys. Just have a couple. So, first, just curious if you can talk about how many of the WAKIX prescribers are actually enrolled in the oxybate REMS? And what I'm trying to get at here is the extent to which you're capturing docs and patients who are oxybate resistant or oxybate hesitant. So, can you talk about that mix? That's number one.

And then number two is a longer-term question. As you think about the potential availability way down the road of orexin agonist or a product like axons reboxetine, how do you think that impacts the longer-term trajectory of WAKIX if at all? Thank you.

Jeff Dayno -- Chief Medical Officer and Interim Chief Executive Officer

Sure, David, thanks for your questions. With regards to the oxybate REMS and the HCPs in that, it's a really interesting dynamic. And I'll let Jeff Dierks to comment on that really interesting dynamic, but our physician universe that we're covering is much broader compared to the number of docs in the oxybate REMS. And, Jeff, do you want to expand on that?

Jeff Dierks -- Chief Commercial Officer

Sure. Thanks, David. So, when you're looking at WAKIX prescribers, to your point, we have penetrated the vast majority of the oxybate REMS enrolled healthcare professionals. And based on publicly available data, there's probably about 4,000-ish, that are in that area.

But to Jeff Dayno's point, we're also penetrating into that 5,500 other healthcare professionals that are not REMS enrolled, and that really allows us to tap into a broader patient opportunity. And that really speaks to the differentiated product profile. The fact that it's nonscheduled, you can write the product with a refill. So, we believe that even with what's going on in the oxybate marketplace with generics and potential launch of Avadel's FT218 in the future, we're well positioned for continued growth, and we're really excited about the growth opportunity that we're seeing within the oxybate REMS enrolled doctors, as well as those that are beyond that space.

And from a patient population, we've disclosed publicly that there are a subset of patients that are on both oxybate and WAKIX. It's looking in the teens, the low double digits. Certainly, we do capture patients that are treatment resistant to stimulants to wake promoting agents to oxybate. So, WAKIX really has a very unique profile that can really help in that treatment algorithm, whether you've had experience with those traditionally scheduled products that are controlled substances or naive to WAKIX.

Thinking about the future landscape, David, I think given the uniqueness of WAKIX, we're well positioned both in the short term and in the long term for continued sustainable growth. I think the fact that it's a nonscheduled treatment options, we talked about, it's the only nonscheduled treatment option approved for both EDS and cataplexy. We have pharmacokinetic data that can show it can be used concomitantly with wake hormone agent modafinil and oxybate. So, the profile is well positioned for healthcare professionals.

And lastly, as you know that this is a very difficult disease to manage. This is very much a polypharmacy market. And I do believe that from what I understand that the synergistic benefits of looking through and within hypocretin and histamine, I think WAKIX is well positioned as future potential products come into the marketplace. It's a big opportunity, lots of brands.

And I think what you see every year, David is all boats rise, all brands are growing, and we're really excited about the difference that we're making in the lives of people living with narcolepsy.

Jeff Dayno -- Chief Medical Officer and Interim Chief Executive Officer

Yeah, David. I would just say that in terms of your second question, we keep a close eye obviously on development programs with the new assets. And as we all know, yes, the Orexin agonist and Orexin is sort of the next novel target in the field. Those programs are early.

And, obviously, there are connections between histamine neurons and hypocretin neurons, mechanistically to what Jeff was saying. Reboxetine, not necessarily a novel mechanism in terms of how that operates. But we will keep a close eye on those programs. And WAKIX will continue to be a differentiated product profile in this market and I think able to use other as monotherapy or concomitant with other treatments now and in the future.

David Amsellem -- Piper Sandler -- Analyst

OK. Helpful. Thank you.

Jeff Dayno -- Chief Medical Officer and Interim Chief Executive Officer

Thanks, David.

Operator

Thank you. Our next question comes from Chris Howerton with Jefferies.

Jeff Dayno -- Chief Medical Officer and Interim Chief Executive Officer

Good morning, Chris.

Chris Howerton -- Jefferies -- Analyst

Yeah. Hey, good morning. Thanks so much for taking the questions. I guess I had two.

One was on kind of the -- I know we talked a little bit around the first-quarter dynamics. But I guess I was wondering, you know, with respect to plan resets, would you expect that to impact existing patients or the addition of new patients in terms of the first-quarter numbers? So, that's question one. And then question two is if you could just give us a little more color around the status of the pediatric narcolepsy package. Can you remind us, are you going to do any clinical work, Or is it just sufficient to take the Bioprojet data to the FDA? Thanks so much.

Jeff Dayno -- Chief Medical Officer and Interim Chief Executive Officer

Sure. Thanks for your question, Chris. Jeff will address on the Q1 dynamics.

Jeff Dierks -- Chief Commercial Officer

Good morning, Chris. So, your question in terms of the seasonal pair dynamics impacting new or existing. Typically what you see across all farm and across the industry, typical headwinds are with the reauthorizations. So, as insurance reset, and you're a chronic patient, on medication year over year that resets, whether you're taking a proton pump inhibitor, cholesterol, diabetes, antidepressant, narcolepsy.

So, what you see is you do get some headwinds in January. One in four Americans changes insurance every year. So, there's going to be paperwork turn, reauthorizations come up. You also have a subset of existing patients.

That's something traditionally felt in January, you get beyond that in February. We traditionally start to see a very strong March coming out of the first quarter leading into a stronger Q2. But even with that Q1 seasonality, Chris, we've talked about, we do expect revenue growth on a year-over-year basis for Q1 and continued growth in the average number of patients on WAKIX in Q1.

Jeff Dayno -- Chief Medical Officer and Interim Chief Executive Officer

Thanks, Jeff. And, Chris, with regards to your second question about the pediatric indication, let me let me provide some clarity on this. And I think, as we shared on the call, our partner Bioprojet received a positive opinion from the CHMP last month, and they're expecting an approval for pediatric indication in Europe within about the next month or two. So, with that, we're working with Bioprojet on a path forward to prepare a supplemental NDA to submit to FDA for pediatric indication.

That will not require any additional development work with regards to potential indication. But we will need to take sort of the European filing and prepare a submission that's appropriate for the FDA. But while that's happening, I also want to comment on a parallel path with regards to pursuing pediatric exclusivity, which is a different regulatory pathway. And for that, we have been engaged with FDA, have gotten feedback last month on what that would require.

And that would require additional clinical development work, which is what needs to be done to get pediatric exclusivity. There is discussion about what trial or trials is needed. So, we've had that engagement. And based on that feedback, the clinical team is preparing the regulatory team, what's called a proposed pediatric study request.

We submit that to the FDA to gain alignment of what needs to be done to gain pediatric exclusivity for WAKIX. So, we'll provide an update on those interactions later in the year. But as a reminder, the main commercial opportunity is in obtaining pediatric exclusivity which would afford us if we're successful there additional six months of patent protection on the back end of the IP.

Chris Howerton -- Jefferies -- Analyst

Yes. No, that's extremely helpful. Thank you to both the Jeffs.

Jeff Dayno -- Chief Medical Officer and Interim Chief Executive Officer

Thanks, Chris.

Operator

Thank you. Our next question comes from Charles Duncan with Cantor Fitzgerald.

Charles Duncan -- Cantor Fitzgerald -- Analyst

Hey, good morning, Jeff and team. Thanks for taking the questions, and congrats on a great quarter. I had a quick commercial question and then a pipeline. Yes, excuse me.

Regarding the commercial question, average patience on, I guess I'm wondering if you can provide any additional color on what you were most impressed with. Were they new patients being prescribed or persistents? That's a commercial question. Then I'll come back around to the pipeline.

Jeff Dayno -- Chief Medical Officer and Interim Chief Executive Officer

OK. All right. Thank you for questions Charles, Jeff [Technical difficulty] average number of patients and where they're coming from?

Jeff Dierks -- Chief Commercial Officer

Sure. And thank you for the question, Charles. I would say I'm equally impressed with the continued addition of new patients. Again, we're entering a new year four.

We continue to see strong top-line prescription demand. But we're also seeing very good retention on patients, right, consistent within the category. For those patients that are staying on WAKIX, we're looking at 90% plus compliance rates, which, when patients really find the right treatment in this category, you do see patients take their medication as prescribed by their doctor. So, we're just finishing up year three.

Personally, for me, I'm really impressed with both of those metrics. I think our award-winning sales team continues to deliver quarter over quarter. As Jeff shared, we have an extremely talented team here. You've got 200 plus strong that are all working to help these patients.

So, I'm pleasantly pleased with both of those metrics. And I anticipate that I'll be pleased with those metrics moving forward each quarter.

Charles Duncan -- Cantor Fitzgerald -- Analyst

OK. And then regarding the pipeline for pitolisant TAM expansion, I guess I'm wondering if you think about idiopathic hypersomnia versus PWS? What are you most interested in? Seems like idiopathic hypersomnia in a Phase 3 should be top of mind. But can we look to PWS top line here in that or actual presentation of the data and articulation of next steps to kind of raise the profile of that particular program versus IH for the potential for pitolisant going forward?

Jeff Dayno -- Chief Medical Officer and Interim Chief Executive Officer

Yes, Charles. It's a great question. So, first of all, I would say that, obviously, both of those patient populations are important because they both have a significant unmet medical need, number one. Of the two, obviously, idiopathic hypersomnia is the near-term opportunity for us and also the larger market opportunity, about 40,000 patients diagnosed.

So, we're really excited about that program. We see significant interest from both the patient community and the physician community in our clinical trial sites. So, we'll provide an update later in the year on enrollment progress, but significant momentum, near-term opportunity on significant market size. But with regards to Prader-Willi syndrome, a pediatric rare neurodevelopmental disorder, also an important development program for us about 15,000 to 20,000 patients diagnosed with PWS in the U.S., and we're actively engaged in preparing and the Phase 2 briefing document, we'll put in a meeting request and look forward to good productive interactions with FDA on advancing that development program to a Phase 3 trial.

So, both are important and to address unmet needs in those patient populations as well as the advancement of our development programs.

Charles Duncan -- Cantor Fitzgerald -- Analyst

OK. Thanks for taking the questions, Jeff.

Operator

Thank you. Our next question comes from Corinne Jenkins with Goldman Sachs.

Corinne Jenkins -- Goldman Sachs -- Analyst

Good morning. Two for me. Maybe first, can you just share more color on the market research you cited particularly I'm interested in what these positions looks like, whether they were primarily sleep specialists or general psychiatrists and what their average patient volume was? And then the other question is separately, as you think about business development and your capacity to do that, how do you think about appropriate leverage targets for the business? Thanks.

Jeff Dayno -- Chief Medical Officer and Interim Chief Executive Officer

Thanks, Corinne. So, Jeff, do you want to take the first question?

Jeff Dierks -- Chief Commercial Officer

Sure. So, Corinne it was a primary market research that we conducted back in November of 2022. Again, we included 70 healthcare professionals with and without experience. So, there was no patient criteria to be eligible because we did want to look into both those who had not yet prescribed WAKIX, as well as those that had prescribed WAKIX.

Specialties included sleep specialists, neurologists, pulmonologist, psychiatrists, and some primary care doctors. And some of the specific questions that we asked them that I cited in our prepared remarks is we asked a healthcare professional how they saw their prescribing of WAKIX changing in the next six months. And as I shared the results demonstrated of those individuals with WAKIX experience, more than 95% of them stated that they would increase or stay the same what they're prescribing. And of those individuals, a subset that had not yet prescribed almost 50% of those healthcare professionals stated and intend to prescribe WAKIX in the next six months.

And so, we're really excited about what these data affirm in our belief in the future growth opportunity for WAKIX and adult narcolepsy. Jeff, back to you for the second question.

Jeff Dayno -- Chief Medical Officer and Interim Chief Executive Officer

Thanks, Jeff. Yes. Corinne, your question about business development, so, first of all, a few comments, and then I'll turn it over to Sandip for his thoughts. So, we have a dedicated business development team and continues to be really active evaluating the BD landscape and potential opportunities.

Importantly we're in a solid financial position to execute on business development. We have a strong cash position, as we said, approximately 346 million at year-end last year. And also, BD continues to be an important priority for us. It's a target-rich environment.

But we're also remaining disciplined in our approach to business development. We want to be strategic in our approach in our decision making. So, when we do announce a deal, it'll make sense, it'll be a good fit for Harmony. In terms of our capacity, and I'll turn it over to Sandip for some thoughts there.

Sandip Kapadia -- Chief Financial Officer

Sure. Jeff. As you mentioned, we have 346 million approximately, of cash, cash equivalents. I think the other thing is, we continue to generate positive cash flow from operations as I mentioned in my call.

Last quarter with beyond the 30 million that we paid out to Bioprojet, but we generated about 57 million there incremental cash. So, we will be generating cash going forward, I think clearly the profile of the company provides us the opportunity to look at leverage. And I think the way I think about it is, look, we also have, in addition, we also have the $100 million delay draw from Blackstone that we could also draw on, which would also be additional debt capital. And generally, as I think about it, I think much as an asset as much closer to market.

There is, I'd be more comfortable with taking on additional leverage. I think it's an earlier asset. We could probably pay it from what we have internally in the cash generation. I think, our ability as we get our top line grows and we have increased profitability also gives us even the cash flow to be able to look at multiple different options and not only just leverage, but there are many other options that we could certainly consider as a company.

Corinne Jenkins -- Goldman Sachs -- Analyst

Thanks, Sandip.

Jeff Dayno -- Chief Medical Officer and Interim Chief Executive Officer

Thanks, Corinne.

Operator

Thank you. Our next question comes from Ami Fadia with Needham.

Ami Fadia -- Needham and Company -- Analyst

Good morning. Congrats on the nice quarter. And I've got two questions. Firstly, can you talk about where you see some [Technical difficulty] for WAKIX in the upcoming quarters? And can you give us some type of qualitative color on how many patients per quarter you might be able to add in 2023? In the past, you've talked about 300 to 400 patient adds per quarter.

If you could comment on that, that would be helpful. And then secondly, as you think about life cycle management for WAKIX, you've expanded your partnership with Bioprojet. Can you talk about what type of life cycle you might have in mind, and where might be the unmet need in say narcolepsy for a different type of formulation of WAKIX? That would be helpful. Thanks.

Jeff Dayno -- Chief Medical Officer and Interim Chief Executive Officer

Sure. Ami. Thanks for the question. Can you repeat the first one.

We lost you for a few seconds there on your first question?

Ami Fadia -- Needham and Company -- Analyst

Sure, the first question is, if you could sort of qualitatively give us a sense of where growth will come from for WAKIX? You'd expanded your reach for your sales force last year, and sounds like you're seeing the benefits of that come through. So, going forward, where do you see growth come? And also in that -- sort of in that context, if you could talk about the number of patient adds up coming up in the upcoming quarters, whether you think 300 to 400 patient adds could be maintained going forward? Thanks.

Jeff Dayno -- Chief Medical Officer and Interim Chief Executive Officer

OK. Sure, Ami. All right. All right.

Jeff Dierks, want to respond to that?

Jeff Dierks -- Chief Commercial Officer

Sure. So, Ami, for your first question just in terms of looking at where we see growth coming from the future. I think as we've shared, there's still a large patient opportunity remaining. And I think where we see growth coming from, we anticipate we're still going to be continuing to add new prescribers on a very regular basis quarter over quarter.

We also expect growth within existing prescribers. Certainly, we know that there are appropriate patients, adult patients living with narcolepsy and those practices as well, that have yet to have a discussion with their healthcare professional about WAKIX. So, with our expanded field sales team, we can now reach the target group of about 9,500 narcolepsy-treating healthcare professionals. So, we see growth coming from both new, as well as existing writers.

So, it continued growth in depth and breadth of our prescriber base. With respect to average patient growth, obviously we're not providing guidance looking forward. But as Sandip shared, if you look backwards three years, we've been relatively consistently delivering. And I think that's probably a good thing to point back to.

We still are very bullish on our ability to continue to grow. We're going to continue to tap into that opportunity as the market allows. Certainly, we've talked about the Q1 seasonal dynamics and some of the headwinds that we would anticipate and implications on patient adds there. We've talked about the second quarter and traditional stronger prescription growth.

Traditionally, in the third quarter, you see less patient visits with a little bit of summer seasonality for chronic conditions where most patients take vacations. They are not in their offices. But in the fourth quarter, you get a lot of those patients coming back in. So, you should expect that traditional rhythm that we've seen in the last three years, and we anticipate that in 2023 moving on, if that helps.

Jeff Dayno -- Chief Medical Officer and Interim Chief Executive Officer

Yes. thanks, Jeff. And, Ami, with regard to your second question and our partnership with Bioprojet and the licensing agreement for new consultant-based assets, so, our thinking around that our strategy is obviously pitolisant as a novel molecule with a novel mechanism of action, and WAKIX performing well in the marketplace, we're looking at opportunities and currently working with Bioprojet in new enhanced formulations, which will give us an opportunity potentially for new IP around some of the innovation in the formulation aspect of that and opportunity to explore the dosage range more and, obviously, extend the runway for further development. Thoughts there where we could initially extend the narcolepsy franchise out further with new IP using the new pitolisant based assets, we could take the current development programs that we're working on now, and then eventually move them to new formulations with a longer runway and longer opportunity in the market.

As well as pitolisant continues to be an interesting molecule and the potential is through developing programs in additional and new patient populations based on its mechanism of action, working through histamine, not just around EDS, but other symptoms we're exploring in our current programs, fatigue as an outcome, as well as the potential impact on cognition. So, with more time in new pitolisant-based assets, that is the strategy, and that's the current thinking.

Ami Fadia -- Needham and Company -- Analyst

That's very helpful. Thank you.

Jeff Dayno -- Chief Medical Officer and Interim Chief Executive Officer

Thanks, Ami.

Operator

Thank you. Our next question comes from Graig Suvannavejh with Mizuho Securities.

Graig Suvannavejh -- Mizuho Securities -- Analyst

Hey, thank you very much. Congrats on a great 2022. I've got two questions. My first is just on the opex.

The opex came in a bit lighter than we were looking for. It seems to be the lightest. It was seen in several quarters. So, just wondering, maybe, Sandip, if you could provide us some modeling assistance, how you're looking at 2023.

And then my second question, it does go back to the current company philosophy around providing guidance. You had mentioned that you feel that you've got a good understanding of the rhythmicity of the business. The drug will be going into its fourth year of launch. So, just wondering why at this point in time, you're not comfortable providing forward-looking guidance at least on revenue.

Thanks.

Jeff Dayno -- Chief Medical Officer and Interim Chief Executive Officer

Sandip, want to address Graig's questions? So, first on opex.

Sandip Kapadia -- Chief Financial Officer

Yes, sure. Just regarding the opex, I think there was nothing unusual I would say in the fourth quarter. Generally, I mean, ebbs and flows with our activity overall. As we think about 2023, we'll see an evolution in our expense base -- is growing, like, for example, on the SG&A side through additional commercialization activities that we put on.

And then, I think on the R&D, it's really the enrollment in our Phase 3 program for IH, which will drive some increases overall. But I would say that it's more gradual increases as opposed to step changes during the quarters. And then, finally, as I mentioned, I think the other thing we want to make sure investors are also looking at is the tax rate overall. We've -- given our success and profitability, we've generated nice profitability, which obviously meant that we used up most of our NOLs.

So, we would expect go-forward tax rate, too. to be in the mid- to upper 20% range. And I think finally, just operating margin, we would expect that to improve as well as our top line grows.

Jeff Dayno -- Chief Medical Officer and Interim Chief Executive Officer

Yes. Thank you. Graig, second question about guidance. And Graig, just we feel the underlying business fundamentals are strong, and we do see -- you mentioned sort of the remit of the business and the consistency in the performance and the key metrics that are provided and when Jeff Dierks talked about the commercial performance.

So I think that's the feeling at this time and Sandip, further thoughts on guidance.

Sandip Kapadia -- Chief Financial Officer

Yeah. Look, I mean, we've shown a nice consistent history. So, we thought that, that was appropriate in terms of being able to model the future. And I think, look, historically, we've seen even the analyst community in this past quarter pretty close within 1 million or so of our actual results.

So, we feel there's a strong understanding by the investor base of our business. It's relatively consistent. We have one product and certainly continue to be confident in the outlook as there's additional growth opportunities both Jeffs discussed. And clearly, the potential to be 1 billion-plus franchise in the coming years in narcolepsy.

And I think we'll continue to evolve that over time. And certainly, we could, in the future, look at more formally providing guidance.

Graig Suvannavejh -- Mizuho Securities -- Analyst

Thank you very much for taking my questions. Congrats again.

Jeff Dayno -- Chief Medical Officer and Interim Chief Executive Officer

Thanks, Graig.

Operator

Thank you. Our next question comes from Danielle Brill with Raymond James.

Danielle Brill -- Raymond James -- Analyst

Hi, guys. Good morning. Thanks for the questions. I guess first is a follow-up to the last one.

Are you comfortable then with 2023 estimates? I think it's around 580 million for the year. And then just to get a bit more granularity on how we should be thinking about our models, what are your expected trends in average revenue per patient and discontinuation rates in 2023? Thank you.

Jeff Dayno -- Chief Medical Officer and Interim Chief Executive Officer

[Inaudible] Sandip start off to address that, and I think Jeff Dierks can sort of provide more color on your second question, Danielle.

Sandip Kapadia -- Chief Financial Officer

Sure. Look, I won't specifically comment, obviously, on 2023 consensus, but I think, as I mentioned, [Inaudible] historically, contestants has for the last many quarters, it's been pretty close to our vicinity of our sales. So, I believe the investment community can hopefully model our business. So, we feel good about the work that you and others are doing to help inform investors overall and continue to look at opportunities.

And certainly, we'll evaluate that as we go forward.

Jeff Dayno -- Chief Medical Officer and Interim Chief Executive Officer

Jeff, you want to -- on Danielle's second question?

Jeff Dierks -- Chief Commercial Officer

Sure. So, Danielle, with respect to average revenue per patient, so it's kind of a function of our patient assistance program and percentage of patients on free goods and one of the things that we've seen is a relatively consistent demand for our patient assistance program throughout 2022. And as we continue to grow, the average number of patients with a consistent PAP demand, you're going to see potentially some slight increases in average revenue per patient as PAP is going to represent a smaller percentage of the overall patients on WAKIX now. Obviously, in the first quarter, there are some other factors as we talked about higher gross and net that you might not see.

But as we continue to grow the average number of patients over time and we have a relatively consistent demand for PAP, you would anticipate a slight increase to the average revenue per patient over time as our overall patient base grows. The second part of your question with respect to discontinuation rates, it's been relatively consistent since our launch, and when we shared publicly available data that about 30% to 50% of all patients on all treatment options by the end of 12 months tend to discontinue any of the medicines in this category, WAKIX has traditionally, and we've seen over the past three years, being in that range. Obviously, it's a chronic condition when patients are out 12-plus months, you might see a small percentage of those patients fall off in any chronic condition. But I would anticipate what you've seen historically in our patient base, we're anticipating similar patient -- patient medication behavior moving forward.

Danielle Brill -- Raymond James -- Analyst

That's helpful. Thank you.

Jeff Dayno -- Chief Medical Officer and Interim Chief Executive Officer

Thanks, Danielle.

Operator

Thank you. At this time, I show no further questions in queue. I would now like to turn the call back to Jeff Dayno for any additional or closing remarks.

Jeff Dayno -- Chief Medical Officer and Interim Chief Executive Officer

Thank you, Todd. And thanks everyone for your interest in Harmony. We finished 2022 on a strong note and look to build on that momentum in 2023 as we execute on our three-pillar growth strategy. We look forward to updating you on our progress on future calls.

Thank you, and have a great day.

Operator

[Operator signoff]

Duration: 0 minutes

Call participants:

Luis Sanay -- Head of Investor Relations

Jeff Dayno -- Chief Medical Officer and Interim Chief Executive Officer

Jeff Dierks -- Chief Commercial Officer

Sandip Kapadia -- Chief Financial Officer

Franc Brisebois -- Oppenheimer and Company -- Analyst

David Amsellem -- Piper Sandler -- Analyst

Chris Howerton -- Jefferies -- Analyst

Charles Duncan -- Cantor Fitzgerald -- Analyst

Corinne Jenkins -- Goldman Sachs -- Analyst

Ami Fadia -- Needham and Company -- Analyst

Graig Suvannavejh -- Mizuho Securities -- Analyst

Danielle Brill -- Raymond James -- Analyst

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