Catalyst Pharmaceuticals 報告了 2023 年第二季度的強勁財務業績,這得益於其藥物 FIRDAPSE 的成功以及 FYCOMPA 的貢獻。該季度總收入為 9960 萬美元,較去年同期大幅增長。
Catalyst 上調了 2023 年的淨收入指引,並宣布將 Vamorolone 添加到其產品組合中。他們提供了有關擴大 FIRDAPSE 在日本使用的努力以及正在進行的業務開發活動的最新信息。 Catalyst 致力於擴大 LEMS 患者使用 FIRDAPSE 的機會,並致力於全球擴張。
他們還獲得了 FYCOMPA 和 Vamorolone 的權利。該公司對實現修訂後的收入指引充滿信心,並討論了未來的戰略。在電話會議期間,他們討論了有關 FIRDAPSE 患者線索和潛在推出 Vamorolone 的問題。他們還討論了 FYCOMPA 的劇本趨勢和銷售隊伍轉型。
Catalyst 期望保持穩定的利潤,並致力於幫助更多患者接受治療。他們的目標是增加使用 FIRDAPSE 的患者數量並減少患者停藥。
使用警語:中文譯文來源為 Google 翻譯,僅供參考,實際內容請以英文原文為主
Operator
Hello, and welcome to the Catalyst Pharmaceuticals Second Quarter 2023 Financial Results Conference Call and Webcast. (Operator Instructions) As a reminder, this conference is being recorded. It's now my pleasure to turn the call over to your host, Chief Financial Officer, Ali Grande. Please go ahead, Ali.
Alicia Grande - CAO, VP, Treasurer & CFO
Good morning, everyone, and thank you for joining our conference call to discuss Catalyst's Second Quarter 2023 Financial Results and Corporate Highlights. Leading the call today is Patrick McEnany, Chairman and Chief Executive Officer. We are also joined by Dr. Steven Miller, our Chief Operating Officer and Chief Scientific Officer and Jeffrey Del Carmen, our Chief Commercial Officer. Before we begin, I want to remind you that in our remarks this morning and in the Q&A session, we will make statements about expected future results, which may be forward-looking statements for purposes of federal securities laws. These statements relate to our current expectations, estimates and projections and do not guarantee future performance. They involve risks, uncertainties and assumptions that are difficult to predict and may prove not to be accurate. Actual results may vary from the expectations contained in our forward-looking statements. Forward-looking statements should be considered only in conjunction with the detailed information contained in our SEC filings, including the risk factors described in our 2022 annual report on Form 10-K.
At this time, I'll turn the call over to Pat.
Patrick J. McEnany - Co-Founder, Chairman, President & CEO
Thanks, Ali, and welcome, everyone, to our second quarter 2023 results conference call. Catalyst's outstanding results for the second quarter of 2023 reflect FIRDAPSE strong organic growth performance, meaningful comp revenue contributions and continued execution excellence. Our achievements reinforce our confidence for sustained growth and further underscore the exceptional execution capabilities across all functional areas of our business.
At this time, I'll present key highlights of our quarterly results. We achieved total revenues of $99.6 million during the quarter, representing 87.5% growth year-over-year. The strong performance reflects FIRDAPSE product net revenues of $64.9 million, achieving a net revenue increase of 22.3% year-over-year. We are confident about the continued growth expectations for FIRDAPSE based on our recent initiatives targeting oncologists to treat the subset of LEMS patients suffering from small cell lung cancer as well as more recent LEMS epidemiology data that Jeff will discuss.
Total revenues were bolstered by FYCOMPAs second quarter net product revenue contribution of $34.6 million, the first full quarter under the Catalyst umbrella. Non-GAAP net income for the second quarter was $60.4 million or $0.57 per basic share and $0.53 per diluted share. This excludes from GAAP net income, noncash stock-based compensation, depreciation, amortization of intangible assets in our income tax provision. The expenses related to the amortization of the intangible assets associated with the acquisition of FYCOMPA and Ruzurgi are approximately $8.5 million for the quarter and $3.3 million in noncash stock-based compensation. GAAP net income for the second quarter was $37.8 million or $0.36 per basic share and $0.33 per diluted share. We ended the quarter with cash and cash equivalents of $178.8 million. Several factors, including continued strong underlying demand for FIRDAPSE from both autoimmune and small cell lung cancer limb patients as well as continued diagnosis of new LEMS patients provides us with the confidence to raise our total net revenue guidance for 2023, up between $380 million to $390 million. Ali will provide more detailed financial highlights during her discussions in this call.
Our operational synergies have been strong, and we are pleased by the efficiencies and enthusiasm demonstrated by our teams in achieving the successful commercial and medical affairs integration of FYCOMPA into our product portfolio. With the integration nearly complete, we are focused on realizing the product's full potential.
In July, we further diversified Catalyst product portfolio with the addition of Vamorolone, a promising dissociated anti-inflammatory steroid candidate for the treatment of Duchenne Muscular Dystrophy, or DMD, a devastating rare neuromuscular disease. As part of the DMD treatment regimen, steroids such as prednisone are commonly administered in addition to other therapies and are known to have notable side effect burden. Vamorolone has the potential to be an innovative new treatment option to address this important unmet need. In clinical studies, Vamorolone demonstrated efficacy with a significant reduction of steroid-associated side effects and benefits for both health, bone health, growth in height and behavior, along with reduced cardiovascular and preliminary risk longer term.
Vamorolone has been granted orphan drug and fast track designation and assigned a PDUFA action date of October 26, 2023. If approved, it would serve as a meaningful advancement to the current DMD standard of care treatment paradigm and represent a pivotal reflection point for the company's growth potential. We anticipate the commercial launch in Q1 of 2024 based on the current time line.
Lastly, with regard to Vamorolone, we'll have more details to provide in our third quarter conference call regarding our commercial launch details, financial impact and expectations for the near and longer term. I want to take this opportunity to make several accounting points on the Vamorolone loan program. We believe that we will take a onetime third quarter charge of $75 million for the acquisition of the Vamorolone license as that expense is considered in process R&D because Vamorolone is not as of yet FDA-approved or commercial. Also, as part of the transaction, we made an approximate $15 million investment in Santhera, representing approximately 11% ownership in Santhera. That investment will be recorded on the balance sheet and marked to the market at the end of each quarter. Additionally, we anticipate a modest increase in OpEx in the second half of this year as we prepare for the anticipated launch of Vamorolone in Q1 of next year. Steve, Jeff and Ali will have more to say about the Vamorolone program shortly.
Last week, we submitted the supplemental NDA to the FDA, seeking to increase the maximum daily dose of FIRDAPSE from 80 to 100 milligrams. We believe that a substantial number of LEMS patients may benefit from an approved increased dosage, and we are confident that this has the potential to address an important need for these patients. In Japan, our Japanese partner, DyDo Pharma continued to make meaningful progress with its ongoing Phase III study of FIRDAPSE or amifampridine. In mid-July, they reported positive interim Phase III results, and we now anticipate the NDA submission to the PMDA in Japan by the end of this year.
Upon submitting the NDA for FIRDAPSE in Japan, our territorial rights to develop a market FIRDAPSE under the license with [SERB] previously BioMarin, expands to include key markets in Asia, Australia, South and Central America. We plan to use this expansion to accelerate our global growth strategy for FIRDAPSE. First, in the targeted markets like China and South Korea before evaluating and pursuing others. Initiatives are underway to identify potential partners in these targeted territories as part of our strategic plan. We look forward to providing further updates on these activities after the NDA submission in Japan.
Clearly, we've been very busy on the business development front, as I discussed earlier. We continue to successfully execute our portfolio expansion efforts as well as our continuing effort to identify additional assets for potential acquisition or in-licensing in the rare neurology and epilepsy therapeutic areas and expand the geographical footprint of our existing products. We are reviewing additional therapies at our commercial stage and/or late-stage product development.
As Jeff will discuss, the recent in-licensing of Vamorolone is a synergistic addition to our FIRDAPSE commercial and medical affairs teams, which will enable Catalyst to provide high levels of service to both DMD physicians and patients and highlights part of our strategy to add new products that leverage our expertise, capabilities in rare disease infrastructure. Our investments in the 2 new assets obtained this year aligned with our capital allocation priorities. Our fiscal discipline has enabled us to fully fund these programs in the entirety using available cash reserves. Our operational and commercial performance continues to fortify our growing cash position, providing a strong foundation to support our future growth initiatives. We expect to have an event-driven second half of the year that started with the closing of the license for Vamorolone in July. The submission of the supplemental NDA to the FDA last week to increase the maximum daily dose of FIRDAPSE from 80 to 100 milligrams per day and just several months away now from a PDUFA action date of October 26 for Vamorolone as well as the NDA submission in Japan by DyDo Pharma by year-end.
As we move forward in the second half of this year and into next year, our business plan is fairly straightforward. Continue to grow the FIRDAPSE and FYCOMPA brands, defend vigorously all of our intellectual property, prepare for a highly successful launch of Vamorolone, geographic expansion of our FIRDAPSE footprint and to bring in another product or company, ideally an epilepsy program.
This past quarter, we are pleased to announce the appointment of Tamar Thompson to Catalyst Board of Directors. Her knowledge and experience in rare diseases, health policy and government affairs will add valuable insights to our Board and strategic planning. I want to take this time to acknowledge and thank our very patient-centric and dedicated team here at Catalyst for all that they do every day to improve the lives of people that are suffering with rare neurological conditions.
I'll now turn the call over to Jeff Del Carmen, our Chief Commercial Officer, who will update you on our commercial activities.
Jeffrey Del Carmen - Chief Commercial Officer
Thanks, Pat, and good morning, everyone. We are very pleased with the Q2 combined net revenue of $99.6 million, fueled by FIRDAPSE's all-time high $64.9 million revenues and meaningful FYCOMPA revenue contributions of $34.6 million, positioning Catalyst well to achieve our revised revenue guidance of $380 million to $390 million.
I'd like to begin by discussing our progress with FIRDAPSE, the only FDA-approved treatment for LEMS. Q2 net sales of $64.9 million represents a 22% increase quarter over the same quarter last year and a 12.8% increase quarter-over-quarter, a direct result of steady new patient starts and low discontinuation rates. As a reminder, LEMS is a chronic condition, so patients typically remain on treatment once diagnosed.
Prescription approval rates were greater than 90% across all payers, government or private commercial insurers. Patients enrolled in Catalyst pathways, including those who are covered by Medicare and accessing foundation assistance had an average co-pay of less than $2 per month. Sustained organic growth will be driven by several key areas. First, we have a pipeline of greater than 450 patients that are diagnosed with LEMS that are not yet on FIRDAPSE. Approximately 50% of new enrollments are generated from these leads. We have identified additional sources for potential new LEMS patients that will enable us to maintain a high level of quality leads for the foreseeable future.
Next, our LEMS education programs have resulted in a significant increase in voltage-gated calcium channel antibody tests, which shorten the diagnostic journey for LEMS patients and lead to more patients being eligible for treatment with FIRDAPSE. It is important to note that we provide these tests at no cost to patients through a partnership with the National Laboratory. Additionally, our focused educational efforts to thoracic oncologists are working as we continue to see an increase in the number of diagnosed small cell lung cancer LEMS patients. The oncology thought leader liaisons have actively focused on the top 30 thoracic oncology centers to accelerate the diagnosis of small cell lung cancer LEMS patients.
Currently, we assess that greater than 80% of small cell lung cancer LEMS patients are undiagnosed, representing a significant opportunity for growth. We are pleased to report that in the coming weeks, the results from a quantitative small cell lung cancer LEMS market size analysis will be presented at an upcoming leading lung conference, which will provide further insight into the small cell lung cancer LEMS patient population. This analysis is part of an initiative to reassess the LEMS market size, which may increase the overall prevalence above 3,000 LEMS patients in the U.S. We hope to provide an update later in Q3.
Now I would like to provide some highlights of our progress with FYCOMPA. We swiftly executed the seamless integration of FYCOMPA into our newly established epilepsy franchise. While we are still in the early stages, FYCOMPA commercialization is progressing well and in line with our expectations. We successfully onboarded and trained 27 FYCOMPA regional account managers equipped with the necessary tools and knowledge to hit the ground running for their first full quarter with Catalyst. We are encouraged by the continued adoption of FYCOMPA as well as the overwhelming support from key opinion leaders and advocacy within the epilepsy community. Q2 net revenues for FYCOMPA were $34.6 million, which adds further confidence toward achieving our FYCOMPA full year 2023 revenue estimate of $130 million. As I have mentioned, adding FYCOMPA to our portfolio is an ideal strategic fit for our existing commercial infrastructure with a 45% overlap in FYCOMPA and FIRDAPSE prescribers an increased share of voice that will benefit both franchises in driving growth. We will begin to fully leverage this overlap later this year.
Let's turn to Vamorolone, a promising best-in-class associative anti-inflammatory steroid treatment for DMD. The U.S. prevalence for DMD is estimated to be between 11,000 and 13,000 patients. Corticosteroids are the current standard of care for treating DMD. Of patients currently being treated for DMD, approximately 75% of these patients receive concomitant steroid treatment. However, steroid treatment is associated with significant side effects. We believe Vamorolone, if approved, would offer an advancement to the current treatment paradigm addressing an important unmet need for DMD patients and caregivers. If approved by the PDUFA date of October 26, 2023, we expect a commercial launch in the first quarter of 2024. We plan to integrate Vamorolone into our neuromuscular franchise, where we can leverage the team's demonstrated capabilities, commercial expertise and experience. We anticipate minimal sales and marketing personnel expansion with fewer than 10 additional team members required. If approved, Vamorolone will be supported by our best-in-class Catalyst Pathways program to help ensure that all eligible patients can access the product.
In summary, we are very pleased with Q2 results and confident in achieving our revised 2023 revenue guidance of $380 million to $390 million. Additionally, we will leverage our demonstrated commercial capabilities as we prepare for the expected launch of Vamorolone. I want to thank the entire team at Catalyst for their unwavering commitment to patients and look forward to a successful second half of 2023.
I will now turn the call over to Dr. Steven Miller, our Chief Operating Officer and Chief Scientific Officer, for an update on R&D activities.
Steven Miller
Thanks, Jeff. Our clinical development and regulatory strategy for FIRDAPSE continues to focus on expanding access to all LEMS patients, enhancing the FIRDAPSE patent to state to maximize its commercial potential and integrating the newly acquired FYCOMPA and Vamorolone products into Catalyst's organization.
First, I would like to discuss our development efforts to increase the indicated maximum dose of FIRDAPSE from 80 milligrams per day to 100 milligrams per day. Catalyst has now submitted a supplementary NDA to the FDA for this change to the maximum daily dose. While there can be no assurance of acceptance or approval of this sNDA, barring any significant issues with the submission, Catalyst anticipates completion of the agency's review in the first quarter of 2024. Currently, there are a number of LEMS patients who are already being treated at 100-milligram daily dosage of FIRDAPSE after their physician worked with the pharmacy and insurance providers to justify the higher dose. Other patients on the current indicated maximum dose of 80 milligrams per day and their physicians have expressed a desire to increase the patient's daily doses to 100 milligrams to optimize therapy. And this supplement, if approved, will help those patients. Based on our Type C meeting with the FDA in May of this year, we believe that our submission strategy constitutes an acceptable basis for seeking a 100-milligram maximum daily dosage for FIRDAPSE.
Regarding our global expansion, we anticipate that DyDo Pharma, our partner in Japan, will submit their NDA for FIRDAPSE Pharmaceuticals and Medical Devices Agency, or PMDA, by the end of 2023. We estimate that there are about 1,200 to 1,300 LEMS patients in Japan. Submissions of this type typically take about 10 months to review by the PMDA, but there can be no assurance that such a submission will be found approvable within this 10-month period. As previously reported, Catalyst acquired U.S. rights to FYCOMPA or perampanel, which is the first and only approved AMPA receptor antagonist or inhibitor. FYCOMPA is approved as an antiseizure medication to treat partial onset seizures with or without secondarily generalized seizures in people with epilepsy who are 4 years of age or older and with other medicines to treat primary generalized tonic-clonic seizures in people with epilepsy who are 12 years of age or older.
As previously reported in March, an article published in Epilepsia showed that perampanel effectively reduces seizures in patients with 8 different rare genetic epilepsies. In the second quarter, researchers published 4 abstracts highlighting FYCOMPA that were subsequently presented both at the 2023 AAM meeting in Boston this quarter and virtually. These were encore presentation sponsored by Eisai, who continues to hold the rights to FYCOMPA in countries and regions outside the U.S. The published abstracts detail the results from 4 independent clinical studies further documenting the uses of perampanel in both focal and generalized epilepsy across a diverse range of patients, including those with a history of psychiatric and behavioral events underaged patients and patients with seizures linked to Lennox-Gastaut Syndrome or LGS. Just this month, researchers published 3 papers summarizing studies of the first safety and efficacy of FYCOMPA in pediatric patients; second, a study on the use of IV FYCOMPA as an alternative to oral FYCOMPA and epilepsy patients. And third, a global pooled real-world extension study focusing on perampanel efficacy and safety by age group when treating focal and generalized epilepsy.
Taken as a whole, all these academic research activity highlights the interest in FYCOMPA's unique mechanism of action, its potential to treat a variety of rare and refractory epilepsies and the ongoing evolution of the epilepsy field toward precision medicine and identification and treatment of rare epilepsies in an area of great interest to Catalyst.
Next, I would like to discuss our recent in-licensing of Vamorolone for the treatment of Duchenne Muscular Dystrophy or DMD from Santhera for the North American territory. Vamorolone is a promising dissociative anti-inflammatory steroid treatment for DMD. In clinical studies, Vamorolone demonstrated efficacy with a significant reduction of corticosteroid associated side effects and benefits for bone health, growth and behavior, offering the potential to address an important unmet medical need in DMD patients. Vamorolone has received FDA orphan drug and Fast Track designations and has been granted a PDUFA action date of October 26, 2023. The FDA has also granted Vamorolone rare pediatric disease designation.
DMD is a rare genetic disorder occurring in about 600 male newborns each year. The prevalence is about 11,000 to 13,000 patients and is gradually increasing as the available treatments continue to increase the survival of patients suffering from this tragic disease. DMD is a condition that weaken skeletal and heart muscle that quickly gets worse with time and is the most common form of muscular dystrophy. It is an X-linked genetic defect to the dystrophin gene and like virtually all X-linked diseases, almost exclusively affects males. Approximately 30% of the patients are amenable to one of the approved exon skipping therapies with the other 70% needing other treatments like corticosteroids. However, even the patients treated with exon skipping treatments continue to meet other treatments like corticosteroids at some level. The majority of DMD cases are inherited for their mother, who is the defective gene carrier, but approximately 30% of the cases are due to new spontaneous genetic mutations that happen randomly and are not inherited.
The Parent Project for Muscular Dystrophy or PPMD reported just this month that an average age of diagnosis is 4.2 years, and the average initiation of corticosteroid use is 5.9 years with 83% of patients taking corticosteroids daily and the remainder taking corticosteroids on a less frequent basis, presumably for safety leases. This report was based on a registry of 5,498 patients spanning 15 years of treatment. It is anticipated that Vamorolone may be a safer and routine clinical use and may lead to earlier initiation of therapy closer to the time of diagnosis and more regular use during therapy.
Earlier this year, [Jaffer Shah] (inaudible) in a meta-analysis of published clinical data for Vamorolone hypothesized how Vamorolone may exhibit better safety profile than other corticosteroids. Vamorolone is a first-in-class steroidal anti-inflammatory drug in that it lacks an oxygen functional group at the 11 position of the steroid ring system. This omitted oxygen functionality is one of 5 molecular interaction sites with the glucocorticoid receptor, thus altering Vamorolone's interaction with this receptor type. This difference sets it apart from all other approved and researched medications in the corticosteroid class.
In animal models, Vamorolone retains the anti-inflammatory properties of steroid medications but lacks its side effects such as growth retardation, bone morbidities and muscular atrophy as a result of this difference. Furthermore, numerous corticosteroids, such as prednisone and Deflazacort, act as agonists of the mineral corticoid receptor, raising blood pressure and volume via the renin-angiotensin system.
In contrast, in preclinical models, Vamorolone has the same activity as the approved Eplerenone or spironolactone drugs, which are both potent antagonist of the mineral corticoid receptors, thus eliminating mineral corticoid side effects in Vamorolone therapy. In summary, Vamorolone may optimize traditional steroidal anti-inflammatory activity while eliminating most of the glucocorticoid and mineral corticoid side effects due to its unique binding and agonism or antagonism of the various corticosteroid receptors. Overall, Vamorolone has the potential to be a differentiated treatment for DMD with a desirable profile in comparison to the current standard of care options, addressing an important unmet medical need for DMD patients starting at an early age.
Moving on to our medical information function. Catalyst's Neuromuscular Medical Science Liaisons, or MSLs, are continuing to reach out to oncology health care providers to build relationships to provide education about the importance of testing their patients for LEMS in order to expand the use of FIRDAPSE by those patients. Oncologists that already treat LEMS in their practices have found that patients treated with FIRDAPSE maintain muscle strength, improving the patients and physicians perception of well-being and the patient's ability to maintain functional mobility. All these domains are critical for the patient's quality of life.
As previously reported, Catalyst has also onboarded the new FYCOMPA MSL team and their new director, all with prior epilepsy experience to support FYCOMPA. FYCOMPA is a mature product for which extensive published information and real-world data is available, including the publications and abstracts I previously mentioned. The MSL team will bring this information to health care providers that treat epilepsy and also address any questions that those physicians may have about using FYCOMPA.
Additionally, Catalyst FYCOMPA MSL team attends epilepsy conferences like AES and IEC in order to keep FYCOMPA in the minds of epilepsy treaters as a potential option for epilepsy treatment. With the in-licensing of Vamorolone, Catalyst will be adding 4 new MSLs specializing in Duchenne muscular dystrophy. Due to the unique mechanistic features of Vamorolone, it has and continues to be an active area of research that will result in an ongoing stream of useful medical information that should be disseminated to doctors so that they can continue to optimize the treatment of their DMD patients. Future updates will be provided as medical information programs are developed and implemented for Vamorolone. As a service to the physician community, Catalyst provides support for the development of continuing medical education or CME programs that are part of the formal ongoing education of health care providers. Catalyst has, over the past 3 years, provided support for 3 CME programs for various aspects of the diagnosis, treatment and management of LEMS. Over this period of time, thousands of health care providers have utilized the CME programs learning modules and hundreds of them are taking CME tests each quarter in order to be granted CME credit toward maintenance of their medical licenses.
In the fourth quarter of 2022, we sponsored a new CME program that targeted oncologists that treat small cell lung cancer due to the correlation between [missed] cancer and associated LEMS. In just over 4 additional months since the use of this course was last reported, almost 100 additional oncology health care providers have taken the CME test for credit. In short, these programs are popular with LEMS treaters and based on the CME test-taking frequency appear to be a valuable part of their ongoing medical education.
At this time, I would like to turn the call over to Alicia Grande, our CFO.
Alicia Grande - CAO, VP, Treasurer & CFO
Thanks, Steve. The results from Catalyst second quarter of 2023 kept us on pace for another year of exceptional financial performance and strong execution. On the business development front, we continue to be busy as we enter into an agreement for the North American license rights for Vamorolone. It is important to note that the Vamorolone transaction did not close until July in the third quarter of 2023.
Our total revenues for the second quarter of 2023 were $99.6 million, an 87.5% increase when compared to total revenues of $53.1 million for the second quarter of 2022. Product revenues net for the second quarter of 2023 from our lead product FIRDAPSE was $64.9 million, a 22.3% increase year-over-year compared to $53 million for the second quarter of 2022. Product revenue net for FYCOMPA was $34.6 million for the second quarter of 2023. Net income before taxes for the second quarter of 2023 was $48.5 million, a 71.8% increase year-over-year compared to $28.2 million for the second quarter of 2022.
We reported GAAP net income for the second quarter of 2023 of $37.8 million or $0.36 per basic and $0.33 per diluted share, an increase of 74.7% year-over-year compared to GAAP net income for the second quarter of 2022 and to $21.6 million or $0.21 per basic and $0.20 per diluted share. Non-GAAP net income for the second quarter of 2023 was $60.4 million or $0.57 per basic and $0.53 per diluted share, which excludes from GAAP net income, the income tax provision of $10.8 million, amortization of intangible assets related to our acquisitions of Ruzurgi FYCOMPA of $8.5 million, stock-based compensation expense of $3.3 million and depreciation of $82,000. This compares to non-GAAP net income for the second quarter of 2022, $30.3 million or $0.29 per basic and $0.28 per diluted share, which excludes from GAAP net income, the income tax revision of $6.6 million stock-based compensation of $2 million and depreciation of $37,000. The above represents an approximately 99.2% increase of non-GAAP net income year-over-year.
Amortization of intangible [acquired] in connection with both the FYCOMPA and the Ruzurgi products was approximately $8.5 million for the second quarter of 2023. We did not have any amortization in the comparable 2022 quarter as we have not acquired either product during the second quarter of 2022. We expect intangible amortization for our acquired products to be approximately $8.5 million for the third quarter of 2023.
Subsequent to the second quarter, during July 2023, we closed the North American license acquisition of Vamorolone and paid approximately $75 million upon closing. We believe this amount will be recorded as a onetime charge to research and development expenses during the third quarter of 2023 and will not impact future intangible amortization. However, it will significantly increase research and development expenses for the third quarter of 2023, making it not comparable to prior periods.
Our effective tax rate for the second quarter of 2023 on an annualized basis was 21.5% compared to 23.7% for the second quarter of 2022. For 2023, the difference to the statutory federal income tax rate of 21% was primarily driven by state income taxes and anticipated annual permanent differences, offset by the orphan drug tax credit claims. The effective tax rate is affected by manufacturers, including the number of stock options exercised in any given period and is likely to fluctuate in future periods. Cost of sales expenses were approximately $12 million in the second quarter of 2023 compared to $7.6 million in the second quarter of 2022 and consisted primarily of royalties. As a reminder, royalties for FIRDAPSE increased by 3% when net product sales exceed $100 million in any calendar year.
In 2023, this threshold was met during the second quarter, making related royalties trend up for the second quarter. We expect all FIRDAPSE net product sales for the remaining of the year to be subject to the higher royalty rate. Cost of sales related to FYCOMPA in 2023 is exclusive of amortization of intangible assets. Research and development expenses were $4 million in both the second quarters of 2023 and 2022. As previously discussed, we expect a significant increase in R&D expenses during the third quarter of 2023 for the onetime expense of $75 million related to the acquisition of the North American license rights for Vamorolone during July 2023. Vamorolone is a late-stage drug candidate with a PDUFA date of October 26, 2023.
SG&A expenses for the second quarter of 2023 totaled $28.4 million compared to $12.9 million in Q2 2022. SG&A expenses increased slightly as a percentage of total operating expenses to 54% for Q2 2023 compared to 53% (inaudible). The overall increase of SG&A expenses in the second quarter of 2023 was principally due to expenses related to FYCOMPA, such as commercial expenses under the transitional services agreement, selling expenses and an increase in headcount, principally for the sales and marketing force hired during May 2023.
As reported, we ended the quarter with cash and cash equivalents of $178.8 million. As a reminder, subsequent to the quarter, during July 2023, we used approximately $75 million of our available cash in connection to the license acquisition of the North American rights for Vamorolone and approximately $15 million for a strategic investment in common stock of the licensed [source], Santhera.
In addition, we paid $10 million under our research license upon the first anniversary of the transaction also occurring in July 2023. We believe our current funds continue to allow us the financial flexibility to fund our existing R&D programs meet our potential contractual obligations and support our strategic initiatives and portfolio expansion efforts, leading to future growth and value creation. In the event, the FDA approved a morale on its PDUFA date in the fourth quarter as we anticipate, Catalyst will owe $36 million in milestones under our agreement with Santhera. More detailed information and analysis of our second quarter 2023 financial performance may be found in our quarterly report on Form 10-Q, which was filed with the Securities and Exchange Commission yesterday, August 9, and can be found on our Investor Relations page on our website at www.catalystpharma.com.
And with that, I'll turn the call over to Pat.
Patrick J. McEnany - Co-Founder, Chairman, President & CEO
Thanks, Ali. In closing, the first half of 2023 has been a remarkable period of accomplishments for the company demonstrated by our success in executing on our strategic vision. As we advance into the second half of this year, we are well poised for sustained momentum to capitalize on our expanded product portfolio and have a sound strategy for our company's future.
I want to thank our Catalyst team, partners and collaborators for their hard work and ongoing commitment to the patient communities. I'm proud of our accomplishments that align with our core mission to deliver value to patients, health care providers and shareholders. At this time, I'd like to turn the call over to the operator to open the line for questions.
Operator
(Operator Instructions) Our first question today is coming from Joe Catanzaro from Piper Sandler.
Joseph Michael Catanzaro - Director & Senior Biotech Analyst
Of course, I want to congratulate you, Pat, on all your success you've had and hope you enjoy a well-deserved retirement. I had 2 questions. Maybe first on FIRDAPSE, it seems that the patient lead pool is holding pretty steady at around 450 patients. Just wanted to know if that lead pool is coming solely from your VGCC testing or are there other sources? And if you have the data, do you know how that lead pool splits between autoimmune and small cell lung cancer patients? And I guess as a follow-up, I think last quarter, you said around 25% of new enrollments came from tumor LEMS. So, wondering if you could speak to that dynamic in 2Q.
Patrick J. McEnany - Co-Founder, Chairman, President & CEO
Thanks, Joe, and thanks for your kind wishes about retirement. Yes, great quarter. Good questions. Jeff, do you want to take the question with regarding to the lead pool?
Jeffrey Del Carmen - Chief Commercial Officer
Sure. So, Joe, when you mentioned the 450 working leads, where we're getting those leads, we've identified new sources and a lot of those are stemming from the increase in the VGCC testing. We partner with National Laboratories that they provide us some leads of patients that had positive VGCC antibody test. So, we know the patients that most likely have LEMS. And then that's when our field force goes and tries to help these patients if FIRDAPSE is the appropriate treatment for those patients. They work directly with the health care providers. So that's where we do that, but we continually source new leads and new -- find new ways to maintain that 450 because we know it's very important in ultra-orphan disease to identify the patients.
As far as the mix goes, the vast majority of these leads are the autoimmune or the non-small cell lung cancer LEMs patients. But we are seeing an increase in the number of these leads that also have small cell lung cancer. And that's what's giving us a validation that all the efforts we're putting out there, the educational efforts and the resources are paying off because we're able to help these patients get diagnosed. I hope that helps, Joe.
Joseph Michael Catanzaro - Director & Senior Biotech Analyst
That's really helpful. Maybe my follow-up is on Vamorolone. I just wanted to see if you could contextualize the future potential launch. And I guess more specifically, Jeff, I think you said there are about 75% of DMD patients that are currently receiving steroids. So just wondering if there are expectations that you would see patients switching, and if so, to what extent and what drives that?
Patrick J. McEnany - Co-Founder, Chairman, President & CEO
Jeff, do you want to take that as well?
Jeffrey Del Carmen - Chief Commercial Officer
Sure. So, Joe, we'll provide more details about the launch probably on our Q3 conference call. But yes, you're correct. And it's about 70% or so of DMD patients are on steroids as the backbone of treatment for DMD. And we do feel like there is a value proposition with V0amorolone versus what's available in the market. And we do feel that some of these patients will like to switch over to Vamorolone when available.
Patrick J. McEnany - Co-Founder, Chairman, President & CEO
Joe, we'll have a lot more to talk about on our third quarter call after the PDUFA date, October 26. So, we're working on our launch details now, budgets, forecast. And I think that we'll be far more informative about our path forward with Vamorolone on that call.
Operator
The next question is coming from Joon Lee from Truist Securities.
Leszek Sulewski - Associate
This is Les on for June. I actually just wanted to echo Joe's comments and congrats to you, Pat, on the retirement, well deserved. So just in regard to FYCOMPA, what are your thoughts on the recent script trends? And could you provide any sort of update on the sales force transition? I have a follow-up.
Patrick J. McEnany - Co-Founder, Chairman, President & CEO
Jeff, do you want to take that?
Jeffrey Del Carmen - Chief Commercial Officer
Sure. Les, the transition has been extremely smooth. Integration is the way we wanted it. It was swift and effective. Now as far as the numbers, we forecasted a flat for FYCOMPA versus 2022. And we've met those expectations. Great news is in the recent 4-week rolling 4-week data from new prescriptions, we are seeing a stabilization and actually a slight growth for the first time. And so, we know our efforts are working. We will continue to analyze how our marketing resources are gaining traction, but we're very confident they will be effective. And the other part is I mentioned it earlier, we're so confident about FYCOMPA because of the overwhelming support that we've received from key opinion leaders and also the advocacy out there. So, it's been a great transition, and we're confident about the future FYCOMPA.
Leszek Sulewski - Associate
That's helpful. And in regard to the cadence for the second half of the year, do you have a little bit more visibility now on FIRDAPSE that gives you, I guess, some sort of comfort level into the guidance? And what do you think about the gross margins as we exit the year? Beginning first half was around 88%, do you think you can achieve that for the second half? And then what's the additional ramp-up in SG&A for the number of sales force that you identified for the Vamorolone launch?
Patrick J. McEnany - Co-Founder, Chairman, President & CEO
Yes, I'll take the last one first, Les. We're not ready to talk about the increase in SG&A yet. As I mentioned, we're putting together the plan. We do believe, obviously, there's going to be an uptick in OpEx in the second half of the year as Jeff starts to add a few more to as a commercial team and marketing team and a few of the MSLs.
With regard to margins, we expect that our margins will stay pretty close to where they are now. They've been fairly consistent year-to-year. And then your first point being the -- what we see in the second half and what gives us confidence with regard to our revised guidance was that -- and we never deviated even in Q1 to talk about the seasonality of most ultra-rare disease drugs. And we experienced that. But despite that, for the first half, FIRDAPSE revenues were up 28% year-over-year, 2023 versus 2022. So consistent with what we've said all along. And remember, with ultra-rare disease drugs, the growth is not necessarily linear because patients are hard to find. Patients are hard to get on therapy once they're found. And so, it's a little bit of a sawtooth, but we're very confident in achieving our guidance and hopefully towards the high end of that guidance for the second half of this year.
Operator
Your next question is coming from Charles Duncan from Cantor Fitzgerald.
Charles Cliff Duncan - Research Analyst
Yes. -- team -- first of all, congrats on the (inaudible) and for you, Pat, congrats on the decision regarding the near-term transition. Sorry for the technical issue. So, congrats on the guidance raise, congrats, Pat to you in your transition -- near-term transition. I had a couple of questions. First of all, with regard to FIRDAPSE, I guess I'm wondering, Jeff, if you had one thing that you would like to see in terms of the future for FIRDAPSE, would it be new patients or increased persistence for FIRDAPSE? And then I had a question regarding FYCOMPA, but I'll wait for your answer on FIRDAPSE.
Jeffrey Del Carmen - Chief Commercial Officer
Sure. I mean the persistence is already very high, Charles, over 90%. So, our focus is really helping more patients get on treatment because we know these patients will benefit from FIRDAPSE. So that's the primary goal.
Charles Cliff Duncan - Research Analyst
Do you have any internal metrics by which you measure that and what your kind of goal number is, if you will, not necessarily granularity, but kind of a percent by this time next year?
Jeffrey Del Carmen - Chief Commercial Officer
We do have an internal goal that, as you know, we have not disclosed how many patients on specific patient count. But yes, we do have that goal, and it's really about getting the net new patients. So, the discontinuation on an annual rate is also very low at about 80%, or I'm sorry, 20% on an annual basis, 20% discontinuation and making sure ensuring that we get a lot of new enrollments per month. So that's what we look at. It's more of net new patients coming in.
The other thing I wanted to add is I mentioned in the script, the revised assessment of the LEMS prevalence in the U.S. It's going to be an important part for us and help us grow well into the future, helping some of these patients. I mentioned it also that greater than 80% of these small cell lung cancer lens patients are unfortunately undiagnosed with LEMS. So that is one of our key focus areas is educating these thoracic oncologists that when small cell and cancer patients are diagnosed have symptoms similar to LEMS symptoms that they do a paraneoplastic panel that includes VGCC antibody test. That's what we're excited about. But we look forward to sharing more information about the increased prevalence here later this quarter.
Charles Cliff Duncan - Research Analyst
Very good. Sorry, I missed those prepared remarks, I'm juggling calls. A quick question on FYCOMPA. I'm wondering if you could provide some color on the synergies that you're seeing in terms of marketing sales and back office efforts relative to FIRDAPSE for FYCOMPA.
Patrick J. McEnany - Co-Founder, Chairman, President & CEO
Jeff?
Jeffrey Del Carmen - Chief Commercial Officer
Yes. So, Charles, it's interesting. We've had a lot of anecdotes from the field and we're just so incredibly thankful that the collaboration is there between the 2 sales forces really. And I know you mentioned the back office, but when you look at some of the FIRDAPSE we've had so many physicians, probably 80%-plus of our physicians have only prescribed once. That talks about that speaks volumes about the ultra-rare part of LEMS, that they're only 3,000 patients out there. So, physicians may only see one patient. So, when you have the FYCOMPA [RAM] that's out there speaking to a physician by FYCOMPA and then it comes up about LEMS, then they have a question they actually collaborate with the RAM from the FIRDAPSE side and say the physician wants to talk to you about this. And we've seen successes where physicians that we did not have targeted that a FYCOMPA RAM went in there connected the 2 and then a LEMS patient was put on FIRDAPSE.
So that's just a quick example of how we can leverage this overlap. And in the back office, it's the same thing. You have speaker programs, or you have lunches with some offices that why not bring both RAMS into that appointment. So, all those things, the collaboration, the overlap and the synergies are great and what we expected, if not more.
Patrick J. McEnany - Co-Founder, Chairman, President & CEO
Charles, remember, we -- the FYCOMPA RAMS have only been on board with us a couple of months. So, they're getting their with catalyst. And I expect in the second half and into next year, we'll see a lot more cross promotion between the 2 products and the 2 teams. We're excited about the synergistic effect of this acquisition for us.
Operator
We have reached the end of our question-and-answer session. I'd like to turn the floor back over to Pat for any further or closing comments.
Patrick J. McEnany - Co-Founder, Chairman, President & CEO
Thank you, everyone, for joining our call today, and we look forward to providing updates on our continued process. Thank you. Have a great day.
Operator
That does conclude today's teleconference and webcast. You may disconnect your line at this time and have a wonderful day. We thank you for your participation today.