Biggest changeSuch forward-looking statements include statements about the benefits to be derived from NUPLAZID ® (pimavanserin), DAYBUE (trofinetide) and our drug candidates, the potential market opportunities for NUPLAZID and DAYBUE and our drug candidates, our strategy for the commercialization of NUPLAZID and DAYBUE, our plans for exploring and developing NUPLAZID and DAYBUE for indications other than PDP or Rett syndrome, respectively, and the commercialization of DAYBUE in jurisdictions other than the U.S., our plans and timing with respect to seeking regulatory approvals, the potential commercialization of any of our drug candidates that receive regulatory approval, the progress, timing, results or implications of clinical trials and other development activities involving NUPLAZID, DAYBUE and our drug candidates, our strategy for discovering, developing and, if approved, commercializing drug candidates, our existing and potential future collaborations, our estimates of future payments, revenues and profitability, our estimates regarding our capital requirements, future expenses and need for additional financing, the potential or expected impacts of geopolitical and macroeconomic developments, possible changes in legislation, and other statements that are not historical facts, including statements which may be preceded by the words “believes,” “expects,” “hopes,” “may,” “will,” “plans,” “intends,” “estimates,” “could,” “should,” “would,” “continues,” “seeks,” “aims,” “projects,” “predicts,” “pro forma,” “anticipates,” “potential” or similar words.
Biggest changeSuch forward-looking statements include statements about the benefits to be derived from our products and our product candidates, the potential market opportunities for our products and our drug candidates, our strategy for the commercialization of our products, our plans for exploring and developing our products for additional indications, the commercialization of DAYBUE or trofinetide in jurisdictions other than the U.S., our plans and timing with respect to seeking regulatory approvals, the potential commercialization of any of our product candidates that receive regulatory approval, the progress, timing, results or implications of clinical trials and other development milestones and activities involving our products and our product candidates, our strategy for discovering, developing and, if approved, commercializing our product candidates, our existing and potential future collaborations, our estimates of future payments, revenues and profitability, our estimates regarding our capital requirements, future expenses and needs for additional financing, the potential or expected impacts of geopolitical and macroeconomic developments, possible changes in legislation, and other statements that are not historical facts, including statements which may be preceded by the words “aims,” “anticipates,” “believes,” “continue,” “could,” “estimates,” “expects,” “hopes,” “intends,” “may,” “plans,” “potential” “predicts,” “pro forma,” “projects,” “seeks,” “should,” “will,” “would,” or similar words.
The following table provides a summary of activity with respect to our sales allowances and accruals for the year ended December 31, 2023 (in thousands): Distribution Fees, Discounts & Chargebacks Co-Pay Assistance Rebates, Data Fees & Returns Total Balance at December 31, 2022 $ 10,923 $ (340 ) $ 26,046 $ 36,629 Provision related to current period sales 97,797 3,979 113,011 214,787 Credits/payments for current period sales (85,641 ) (4,499 ) (26,957 ) (117,097 ) Credits/payments for prior period sales (10,923 ) 340 (26,046 ) (36,629 ) Balance at December 31, 2023 $ 12,156 $ (520 ) $ 86,054 $ 97,690 68 Cost of Product Sales Cost of product sales was $41.6 million and $10.2 million in 2023 and 2022, respectively, or approximately 6% and 2% of net product sales, respectively.
The following table provides a summary of activity with respect to our sales allowances and accruals for the year ended December 31, 2023 (in thousands): Distribution Fees, Discounts & Chargebacks Co-Pay Assistance Rebates, Data Fees & Returns Total Balance at December 31, 2022 $ 10,923 $ (340 ) $ 26,046 $ 36,629 Provision related to current period sales 97,797 3,979 113,011 214,787 Credits/payments for current period sales (85,641 ) (4,499 ) (26,957 ) (117,097 ) Credits/payments for prior period sales (10,923 ) 340 (26,046 ) (36,629 ) Balance at December 31, 2023 $ 12,156 $ (520 ) $ 86,054 $ 97,690 Cost of Product Sales Cost of product sales was $41.6 million and $10.2 million in 2023 and 2022, respectively, or approximately 6% and 2% of net product sales, respectively.
However, subsequent changes in estimates may result in a material change in our accruals, which could also materially affect our balance sheet and results of operations. Chargebacks : Chargebacks are discounts and fees that relate to contracts with government and other entities purchasing from the SDs at a discounted price.
However, subsequent changes in estimates may result in a material change in our accruals, which could also materially affect our balance sheet and results of operations. 67 Chargebacks : Chargebacks are discounts and fees that relate to contracts with government and other entities purchasing from the SDs at a discounted price.
We believe the following critical accounting policies and estimates describe the more significant judgments and estimates used in the preparation of our consolidated financial statement. 66 Product Sales, Net We sell NUPLAZID through SPs and SDs.
We believe the following critical accounting policies and estimates describe the more significant judgments and estimates used in the preparation of our consolidated financial statement. Product Sales, Net We sell NUPLAZID through SPs and SDs.
Our future capital requirements will depend on, and could increase significantly as a result of, many factors, including: • the costs of acquiring additional product candidates or research and development programs; • the scope, prioritization and number of our research and development programs; • the ability of our collaborators and us to reach the milestones and other events or developments triggering payments under our collaboration or license agreements, or our collaborators’ ability to make payments under these agreements; • our ability to enter into new collaboration and license agreements; • the progress in, and the costs of, our ongoing and planned development activities for pimavanserin, post-marketing studies for DAYBUE to be conducted over the next several years, and ongoing and planned commercial activities for NUPLAZID and DAYBUE; • the costs of our development activities for our early-stage pipeline programs; • the costs of commercializing NUPLAZID and DAYBUE, including the maintenance and development of our sales and marketing capabilities; • the costs of establishing, or contracting for, sales and marketing capabilities for our product candidates; 70 • the amount of U.S. product sales from NUPLAZID and DAYBUE; • the costs of preparing applications for regulatory approvals for DAYBUE in jurisdictions other than the U.S., for NUPLAZID in additional indications other than PDP and for other product candidates, as well as the costs required to support review of such applications; • the costs of manufacturing and distributing NUPLAZID and DAYBUE for commercial use in the U.S.; • our ability to obtain regulatory approval for, and subsequently generate product sales from, NUPLAZID for the negative symptoms of schizophrenia, or from DAYBUE, and our product candidates; • the extent to which we are obligated to reimburse collaborators or collaborators are obligated to reimburse us for costs under collaboration agreements; • the costs involved in filing, prosecuting, enforcing, and defending patent claims and other intellectual property rights; • the costs of maintaining or securing manufacturing arrangements for clinical or commercial production of pimavanserin, trofinetide or other product candidates; and • the costs associated with litigation, including the costs incurred in defending against any product liability claims that may be brought against us related to NUPLAZID or DAYBUE.
Our future capital requirements will depend on, and could increase significantly as a result of, many factors, including: • the costs of acquiring additional product candidates or research and development programs; • the scope, prioritization and number of our research and development programs; • the ability of our collaborators and us to reach the milestones and other events or developments triggering payments under our collaboration or license agreements, or our collaborators’ ability to make payments under these agreements; • our ability to enter into new collaboration and license agreements; • the progress in, and the costs of, our ongoing and planned development activities for pimavanserin, post-marketing studies for DAYBUE to be conducted over the next several years, and ongoing and planned commercial activities for our products; • the costs of our development activities for our product candidates; • the costs of commercializing our products, including the maintenance and development of our sales and marketing capabilities; • the costs of establishing, or contracting for, sales and marketing capabilities for our product candidates; • the amount of U.S. product sales from our products; • the costs of preparing applications for regulatory approvals for DAYBUE in jurisdictions other than the U.S., for NUPLAZID in additional indications other than PDP and for other product candidates, as well as the costs required to support review of such applications; • the costs of manufacturing and distributing our products for commercial use in the U.S.; • our ability to obtain regulatory approval for, and subsequently generate product sales from, NUPLAZID for the negative symptoms of schizophrenia, or from DAYBUE, and our product candidates; • the extent to which we are obligated to reimburse collaborators or collaborators are obligated to reimburse us for costs under collaboration agreements; 71 • the costs involved in filing, prosecuting, enforcing, and defending patent claims and other intellectual property rights; • the costs of maintaining or securing manufacturing arrangements for clinical or commercial production of pimavanserin, trofinetide or other product candidates; and • the costs associated with litigation, including the costs incurred in defending against any product liability claims that may be brought against us related to our products.
As such, we are not materially exposed to any financing, liquidity, market, or credit risk that could arise if we had engaged in these relationships. Recent Accounting Pronouncements See Item 15 of Part IV, “Notes to Consolidated Financial Statements—Note 2—Summary of Significant Accounting Policies.” 72
As such, we are not materially exposed to any financing, liquidity, market, or credit risk that could arise if we had engaged in these relationships. Recent Accounting Pronouncements See Item 15 of Part IV, “Notes to Consolidated Financial Statements—Note 2—Summary of Significant Accounting Policies.” 73
Thus the cost of sales as a percentage of net sales of DAYBUE for the year ended December 31, 2023 was affected by use of the initial pre-launch inventory, which was previously expensed as research and development expense, and is referred to as zero cost inventories.
Thus the cost of sales as a percentage of net sales of DAYBUE for the year ended December 31, 2024 and 2023 were affected by use of the initial pre-launch inventory, which was previously expensed as research and development expense, and is referred to as zero cost inventories.
We cannot forecast with any degree of certainty which product opportunities will be subject to future collaborative or licensing arrangements, when such arrangements will be secured, if at all, and to what degree any such arrangements would affect our development plans and capital requirements.
We cannot forecast with any degree of certainty which product candidates will be subject to future collaborative or licensing arrangements, when such arrangements will be secured, if at all, and to what degree any such arrangements would affect our development plans and capital requirements.
We do not expect our cost of product sales for DAYBUE to increase significantly as a percentage of net product sales in future periods as we continue to produce inventory for future sales. We expect to finish selling the zero cost inventories of DAYBUE in 2024.
We do not expect our cost of product sales for DAYBUE to increase significantly as a percentage of net product sales in future periods as we continue to produce inventory for future sales. We expect to finish selling the zero cost inventories of DAYBUE in 2025.
Also included in selling, general and administrative expenses are fees paid to external service providers to support our commercial activities associated with NUPLAZID and DAYBUE, professional fees associated with legal and accounting services, costs associated with patents and patent applications for our intellectual property and charitable donations to independent charitable foundations that support Parkinson’s disease patients generally.
Also included in selling, general and administrative expenses are fees paid to external service providers to support our commercial activities associated with our products, professional fees associated with legal and accounting services, costs associated with patents and patent applications for our intellectual property and charitable donations to independent charitable foundations that support Parkinson’s disease patients generally.
The FDA approved DAYBUE in March 2023 for the treatment of Rett syndrome and we launched the product in the United States in April 2023. Cost of Product Sales Cost of product sales consists of third-party manufacturing costs, freight, and indirect overhead costs associated with sales of NUPLAZID and DAYBUE.
The FDA approved DAYBUE in March 2023 for the treatment of Rett syndrome and we launched the product in the United States in April 2023. Cost of Product Sales Cost of product sales consists of third-party manufacturing costs, freight, and indirect overhead costs associated with sales of our products.
Financial Operations Overview Product Revenues Net product sales consist of sales of NUPLAZID and DAYBUE. The FDA approved NUPLAZID in April 2016 for the treatment of hallucinations and delusions associated with PDP and we launched the product in the United States in May 2016.
Financial Operations Overview Product Revenues Net product sales consist of sales of our products. The FDA approved NUPLAZID in April 2016 for the treatment of hallucinations and delusions associated with PDP and we launched the product in the United States in May 2016.
Cost of product sales as a percentage of net product sales for NUPLAZID remains flat in 2023 as compared to 2022.
Cost of product sales as a percentage of net product sales for NUPLAZID remained flat in 2023 as compared to 2022.
While our current development efforts are primarily focused on advancing the development of pimavanserin for the treatment of the negative symptoms of schizophrenia and the development of ACP-101, ACP-204 and other early-stage programs, we anticipate that we will make determinations as to which programs to pursue and how much funding to direct to each program on an ongoing basis in response to the scientific and clinical success of each product candidate, as well as an ongoing assessment of the commercial potential of each opportunity and our financial position.
While our current development efforts are primarily focused on advancing the development of ACP-101, ACP-204 and other early-stage product candidates, we anticipate that we will make determinations as to which programs to pursue and how much funding to direct to each program on an ongoing basis in response to the scientific and clinical success of each product candidate, as well as an ongoing assessment of the commercial potential of each candidate and our financial position.
Information in the following discussion for a yearly period means for the year ended December 31 of the indicated year. Overview Background We are a biopharmaceutical company focused on the development and commercialization of innovative medicines that address unmet medical needs in CNS disorders and rare diseases.
Information in the following discussion for a yearly period means for the year ended December 31 of the indicated year. Overview Background We are a biopharmaceutical company focused on the development and commercialization of innovative medicines that address unmet medical needs in CNS disorders and rare diseases. We have two core franchises in neuroscience and neuro-rare diseases.
We anticipate that our quarterly and annual results of operations will be impacted for the foreseeable future by several factors, including the progress and timing of expenditures related to our commercial activities associated with NUPLAZID and DAYBUE and the extent to which we generate revenue from product sales, our development of pimavanserin for the negative symptoms of schizophrenia, our further development of our early-stage pipeline programs and the progress and timing of expenditures related to studies of DAYBUE pursuant to our post-marketing commitments.
We anticipate that our quarterly and annual results of operations will be impacted for the foreseeable future by several factors, including the progress and timing of expenditures related to our commercial activities associated with our products and the extent to which we generate revenue from product sales, our development of pimavanserin for the negative symptoms of schizophrenia, our further development of our early-stage product candidates and the progress and timing of expenditures related to studies of DAYBUE pursuant to our PMRs.
Net cash provided by operating activities was $16.7 million in 2023 compared to net cash used in operating activities of $114.0 million in 2022 and $125.7 million in 2021.
Net cash provided by operating activities was $157.7 million in 2024 compared to net cash provided by operating activities of $16.7 million in 2023 and net cash used in operating activities of $114.0 million in 2022.
Rett syndrome also occurs in boys, albeit far less frequently. Typically, between six to eighteen months of age, patients experience a period of rapid decline with loss of purposeful hand use and spoken communication and inability to independently conduct activities of daily living. Symptoms also include seizures, hand movements or stereotypies, disorganized breathing patterns, scoliosis and sleep disturbances, among others.
Typically, between six to eighteen months of age, patients experience a period of rapid decline with loss of purposeful hand use and spoken communication and inability to independently conduct activities of daily living. Symptoms also include seizures, hand movements or stereotypies, disorganized breathing patterns, scoliosis and sleep disturbances, among others.
For example, due to geopolitical and macroeconomic developments, including the Ukraine-Russia military conflict and related sanctions, and the ongoing conflict in Israel and surrounding areas, the global credit and financial markets have experienced extreme volatility and disruptions, including diminished liquidity and credit availability, declines in consumer confidence, declines in economic growth, increases in unemployment rates and uncertainty about economic stability.
For example, due to geopolitical and macroeconomic developments, including the Ukraine-Russia military conflict and related sanctions, the ongoing conflicts in the Middle East, tariffs and trade tensions, the global credit and financial markets have experienced extreme volatility and disruptions, including diminished liquidity and credit availability, declines in consumer confidence, declines in economic growth, increases in unemployment rates and uncertainty about economic stability.
We cannot predict with certainty what the full impact that geopolitical and macroeconomic developments, including the ongoing military conflict between Ukraine and Russia and the ongoing conflict in Israel and surrounding areas may have on our business, results of operations, financial condition and prospects.
We cannot predict with certainty what the full impact that geopolitical and macroeconomic developments, including the ongoing military conflict between Ukraine and Russia and in the Middle East, and tariffs and trade tensions may have on our business, results of operations, financial condition and prospects.
Due to these fluctuations, we believe that the period-to-period comparisons of our operating results are not a good indication of our future performance. Comparison of the Years Ended December 31, 2023 and 2022 Product Sales, Net Net product sales, comprised of NUPLAZID and DAYBUE, were $726.4 million and $517.2 million for the years ended December 31, 2023 and 2022, respectively.
Due to these fluctuations, we believe that the period-to-period comparisons of our operating results are not a good indication of our future performance. 68 Comparison of the Years Ended December 31, 2024 and 2023 Product Sales, Net Net product sales, comprised of our products, were $957.8 million and $726.4 million for the years ended December 31, 2024 and 2023, respectively.
Net product sales of NUPLAZID were $549.2 million and $517.2 million in 2023 and 2022, respectively. The increase in net product sales of NUPLAZID of $32.0 million was due to the growth in NUPLAZID unit sales as well as a higher average net selling price in NUPLAZID in 2023 compared to 2022.
Net product sales of NUPLAZID were $609.4 million and $549.2 million in 2024 and 2023, respectively. The increase in net product sales of NUPLAZID of $60.2 million was due to the growth in NUPLAZID unit sales as well as a higher average net selling price in NUPLAZID in 2024 compared to 2023.
We have entered into various collaboration, licensing and merger agreements which generally include upfront license fees, development and commercial milestone payments upon achievement of certain clinical and commercial development and annual net sales milestones, as well as royalties calculated as a percentage of net product sales, with rates that vary by agreement.
In such event, we would not be liable for the full amount of the agreement. 72 We have entered into various collaboration, licensing and merger agreements which generally include upfront license fees, development and commercial milestone payments upon achievement of certain clinical and commercial development and annual net sales milestones, as well as royalties calculated as a percentage of net product sales, with rates that vary by agreement.
The decrease in net cash provided by financing activities in 2022 relative to 2021 was primarily due to a decrease in proceeds resulting from the exercise of employee stock options.
This decrease in net cash provided by financing activities in 2024 relative to 2023 was attributable primarily to a decrease in proceeds resulting from the exercise of employee stock options. The increase in net cash provided by financing activities in 2023 relative to 2022 was primarily due to an increase in proceeds resulting from the exercise of employee stock options.
We anticipate that the level of cash used in our operations will fluctuate in future periods depending on the levels of spending required for our ongoing and planned commercial activities for NUPLAZID and DAYBUE, our ongoing and planned development activities for pimavanserin for the negative symptoms of schizophrenia, ACP-101 as a treatment for Prader-Willi syndrome and ACP-204 as a treatment for ADP, studies to be conducted pursuant to our post-marketing commitments, our ongoing and planned development activities for other early-stage pipeline programs and strategic business development to further expand our portfolio.
We anticipate that the level of cash used in our operations will fluctuate in future periods depending on the levels of spending required for our ongoing and planned commercial activities for our products, our ongoing and planned development activities for pimavanserin for the negative symptoms of schizophrenia, ACP-101 as a treatment for PWS and ACP-204 as a treatment for ADP, studies to be conducted pursuant to our PMRs, our ongoing and planned development activities for other early- and late-stage product candidates and strategic business development to further expand our portfolio.
We expect that our cash, cash equivalents, and investment securities will be sufficient to fund our planned operations through and beyond the next 12 months. We may require additional financing in the future to fund our operations.
We expect that our cash, cash equivalents and investment securities, as well as funds generated by anticipated sales of our products, will be sufficient to fund our planned operations through and beyond the next 12 months. We may require additional financing in the future to fund our operations.
The decrease in net cash provided by investing activities in 2023 compared to 2022 was primarily due to milestone payment of $40 million to Neuren and decreased net sale and maturities of investment securities. The increase in net cash provided by investing activities in 2022 compared to 2021 was primarily due to increased net maturities of investment securities.
The decrease in net cash provided by investing activities in 2023 compared to 2022 was primarily due to milestone payment of $40 million to Neuren and decreased net sale and maturities of investment securities. Net cash provided by financing activities decreased to $6.8 million in 2024 compared to $25.1 million in 2023 and $8.2 million in 2022.
At this time, due to the risks inherent in regulatory requirements and clinical development, we are unable to estimate with certainty the costs we will incur for the ongoing or additional development of pimavanserin for the negative symptoms of schizophrenia or to support the commercialization of DAYBUE, as well as the further development of our early-stage pipeline programs.
At this time, due to the risks inherent in regulatory requirements and clinical development, we are unable to estimate with certainty the costs we will incur to support the commercialization of DAYBUE, as well as the further development of our early-stage product candidates.
For restricted stock units requiring satisfaction of both market and service conditions, the estimated fair values are generally expensed over the longest of the explicit, implicit and derived service periods. Performance-based stock awards vest upon the achievement of certain pre-defined company-specific performance-based criteria.
For restricted stock units requiring satisfaction of both market and service conditions, the estimated fair values are generally expensed over the longest of the explicit, implicit and derived service periods.
However, subsequent changes in estimates may result in a material change in our accruals, which could also materially affect our balance sheet and results of operations. 67 Stock-Based Compensation The fair value of each employee stock option and each employee stock purchase plan right granted is estimated on the grant date under the fair value method using the Black-Scholes valuation model, which requires us to make a number of assumptions including the estimated expected life of the award and related volatility.
Stock-Based Compensation The fair value of each employee stock option and each employee stock purchase plan right granted is estimated on the grant date under the fair value method using the Black-Scholes valuation model, which requires us to make a number of assumptions including the estimated expected life of the award and related volatility.
Our primary uses of cash and operating expenses relate to paying employees and consultants, administering clinical trials, marketing our products, and providing technology and facility infrastructure to support our operations.
Our primary uses of cash and operating expenses relate to paying employees and consultants, administering clinical trials, marketing our products, and providing technology and facility infrastructure to support our operations. We also make investments in our office and laboratory facilities to enable continued expansion of our business.
We also enter into short-term agreements with various vendors and suppliers of goods and services in the normal course of operations through purchase orders or other documentation, or that are undocumented except for an invoice. Such short-term agreements are generally outstanding for periods less than a year and are settled by cash payments upon delivery of goods and services.
In addition to operating leases, we enter into certain other long-term commitments for goods and services that are outstanding for periods greater than one year. We also enter into short-term agreements with various vendors and suppliers of goods and services in the normal course of operations through purchase orders or other documentation, or that are undocumented except for an invoice.
We use external service providers to manufacture our product candidates and for the majority of the services performed in connection with the preclinical and clinical development of pimavanserin, trofinetide, and our early-stage programs.
In addition, we expect to incur increased research and development expenses as a result of advancement of our early-stage product candidates. We use external service providers to manufacture our product candidates and for the majority of the services performed in connection with the preclinical and clinical development of our product candidates.
Income Tax Expense Because we maintain a full valuation allowance against our net deferred tax assets, income tax expense is expected to primarily consist of current federal and state tax expense as a result of taxable income anticipated or incurred in certain jurisdictions.
During the year ended December 31, 2024, we sold the PRV to a third party for the aggregate net proceeds of $146.5 million. 66 Income Tax Expense Because we maintain a full valuation allowance against our net deferred tax assets, income tax expense is expected to primarily consist of current federal and state tax expense as a result of taxable income anticipated or incurred in certain jurisdictions.
The following table summarizes our research and development expenses for the years ended December 31, 2023, 2022, and 2021 (in thousands): Years Ended December 31, 2023 2022 2021 Costs of external service providers: NUPLAZID (pimavanserin) $ 55,527 $ 62,746 $ 73,696 DAYBUE (trofinetide) 32,065 62,300 39,814 ACP-101 11,887 2,085 — ACP-204 43,768 16,898 2,569 Early-stage programs 26,789 45,803 33,395 Upfront and milestone payments* 102,500 88,741 10,999 Subtotal 272,536 278,573 160,473 Internal costs 61,675 60,422 56,973 Stock-based compensation 17,408 22,580 21,969 Total research and development expenses $ 351,619 $ 361,575 $ 239,415 _____________________ * Includes upfront and milestone consideration as well as transaction costs associated with acquired in-process research and development.
To the extent that external expenses are not attributable to a specific project, they are allocated proportionally to each of the projects. 65 The following table summarizes our research and development expenses for the years ended December 31, 2024, 2023, and 2022 (in thousands): Years Ended December 31, 2024 2023 2022 Costs of external service providers: NUPLAZID (pimavanserin) $ 34,369 $ 55,527 $ 62,746 DAYBUE (trofinetide) 30,677 32,065 62,300 ACP-101 30,401 11,887 2,085 ACP-204 54,389 43,768 16,898 Early-stage product candidates 44,703 26,789 45,803 Upfront and milestone payments* 34,500 102,500 88,741 Subtotal 229,039 272,536 278,573 Internal costs 60,110 61,675 60,422 Stock-based compensation 14,100 17,408 22,580 Total research and development expenses $ 303,249 $ 351,619 $ 361,575 _____________________ * Includes upfront and milestone consideration as well as transaction costs associated with acquired in-process research and development.
Expense related to these performance-based stock awards is generally recognized ratably over the expected performance period once the pre-defined performance-based criteria for vesting becomes probable. See also Item 15 of Part IV, “Notes to Consolidated Financial Statements—Note 2—Summary of Significant Accounting Policies” for further discussion of our assumptions and estimates related to our stock-based compensation.
The fair value of these PSUs is estimated using a Monte Carlo model. Expense related to these PSUs is recognized ratably over the three-year measurement period. See also Item 15 of Part IV, “Notes to Consolidated Financial Statements—Note 2—Summary of Significant Accounting Policies” for further discussion of our assumptions and estimates related to our stock-based compensation.
There was a similar level of clinical spend and business development investment year over year. Selling, General and Administrative Expenses Selling, general and administrative expenses increased to $406.6 million in 2023, including $48.0 million in stock-based compensation expense, from $369.1 million in 2022, including $44.5 million in stock-based compensation expense.
Selling, General and Administrative Expenses Selling, general and administrative expenses increased to $406.6 million in 2023, including $48.0 million in stock-based compensation expense, from $369.1 million in 2022, including $44.4 million in stock-based compensation expense.
As of December 31, 2023, we may be required to make milestone payments up to $3.4 billion in the aggregate. These payments are contingent upon achieving future development, regulatory and commercial milestones. We are also required to make royalty payments in connection with the sale of products developed under those agreements.
As of December 31, 2024, we may be required to make milestone payments up to $4.0 billion in the aggregate. $1.1 billion payments are contingent upon achieving future development and regulatory milestones, and $2.9 billion payments are contingent upon achieving future commercial milestones.
The following table provides a summary of milestone payments that Neuren is eligible to receive based on the achievement of certain sales milestones under the terms of the expanded agreement: Territory First Commercial Sales Milestones Total Sales Milestones Europe $35 million (Rett syndrome) $10 million (2 nd indication) Up to $170 million Japan $15 million (Rett syndrome) $4 million (2 nd indication) Up to $110 million Rest of World __ Up to $83 million In addition to the treatment of hallucinations and delusions associated with the PDP, we believe that pimavanserin has the potential as a treatment of the negative symptoms of schizophrenia.
The following table provides a summary of milestone payments that Neuren is eligible to receive based on the achievement of certain sales milestones under the terms of the expanded agreement: Territory First Commercial Sales Milestones Total Sales Milestones Europe $35 million (Rett syndrome) $10 million (2 nd indication) Up to $170 million Japan $15 million (Rett syndrome) $4 million (2 nd indication) Up to $110 million Rest of World __ Up to $83 million In addition to these commercial products, we have a portfolio of product candidates and research programs that are designed to address significant unmet medical needs in CNS disorders and rare diseases.
The decrease in net cash used in operating activities in 2022 relative to 2021 was primarily due to an increase in our net revenues as well as decreased sales and marketing costs, partially offset by increased research and development costs.
The increase in net cash provided by operating activities in 2024 relative to 2023 was primarily due to an increase in our net revenues, decreased research and development costs and proceeds from sale of a non-financial asset , partially offset by increased sales and marketing costs .
In November 2023, we initiated a Phase 2 study evaluating the efficacy and safety of ACP-204 for the treatment of hallucinations and delusions associated with ADP. ACP-204 is a new chemical entity for which we hold the worldwide rights.
In November 2023, we initiated a Phase 2 study evaluating the efficacy and safety of ACP-204 for the treatment of hallucinations and delusions associated with ADP. We plan to initiate an additional Phase 2 study of ACP-204 in LBDP in the third quarter of 2025.
Under the terms of the 2018 agreement, Neuren received an upfront payment of $10.0 million and is eligible to receive milestone payments of up to $400.0 million based on the achievement of certain development and sales milestones for Rett syndrome in North America, of which, $50 million has been paid to date.
The FDA approval of DAYBUE for the treatment of Rett syndrome was based on the positive results from our pivotal Phase 3 LAVENDER study which demonstrated statistically significant improvement over placebo for both co-primary endpoints as well as the key secondary endpoint. 63 Under the terms of the 2018 agreement, Neuren received an upfront payment of $10.0 million and is eligible to receive milestone payments of up to $400.0 million based on the achievement of certain development and sales milestones for Rett syndrome in North America, of which, $50 million has been paid to date.
Contingent on the level of business development activities we may complete as well as pipeline programs we may advance, we may continue to incur operating losses for the next few years as we incur significant research and development costs and costs for continued commercialization of NUPLAZID and DAYBUE.
As of December 31, 2024, we had an accumulated deficit of approximately $2.2 billion. Contingent on the level of business development activities we may complete as well as pipeline programs we may advance, we may incur operating losses as we incur significant research and development costs and costs for continued commercialization of our products.
Net cash provided by investing activities totaled $32.0 million in 2023 compared to net cash provided by investing activities of $73.2 million in 2022 and net cash used in investing activities of $71.1 million in 2021.
Net cash used in investing activities totaled $30.5 million in 2024 compared to net cash provided by investing activities of $32.0 million in 2023 and net cash provided by investing activities of $73.2 million in 2022. The increase in net cash used in investing activities in 2024 compared to 2023 was primarily due to increased net purchases of investment securities.
However, we do not expect that the cost of sales as a percentage of net sales of DAYBUE will increase significantly once we commence the sales of full cost inventories. 64 Research and Development Expenses Our research and development expenses have consisted primarily of fees paid to external service providers, salaries and related personnel expenses, facilities and equipment expenses, and other costs incurred related to pre-commercial product candidates.
Research and Development Expenses Our research and development expenses have consisted primarily of fees paid to external service providers, salaries and related personnel expenses, facilities and equipment expenses, and other costs incurred related to pre-commercial product candidates. We charge all research and development expenses to operations as incurred.
Liquidity and Capital Resources We have funded our operations primarily with revenues from sales of NUPLAZID and DAYBUE since their approvals, and through sales of our equity securities and interest income.
The increase in selling, general and administrative expenses was primarily due to increased commercial costs associated with the DAYBUE launch, partially offset by reductions in expenses associated with NUPLAZID. Liquidity and Capital Resources We have funded our operations primarily with revenues from sales of our products since their approvals, and through sales of our equity securities and interest income.
We completed enrollment in ADVANCE-2 and expect that top-line results will be available in the first quarter of 2024. 63 In June 2023, we announced that we added a new Phase 3 development candidate to our rare disease portfolio, ACP-101 (intranasal carbetocin), for the treatment of hyperphagia (an intense persistent sensation of hunger accompanied by food preoccupations, an extreme drive to consume food, food-related behavior problems, and a lack of normal satiety) in PWS.
Our most advanced product candidate is ACP-101 (intranasal carbetocin) for the treatment of hyperphagia in PWS, a neuro rare disease. Hyperphagia is an intense persistent sensation of hunger accompanied by food preoccupations, an extreme drive to consume food, food-related behavior problems, and a lack of normal satiety.
We have fulfilled three of the four studies. The fourth commitment has been completed and we are awaiting FDA’s acknowledgement and acceptance. In connection with the FDA approval of DAYBUE, we are required to conduct post-marketing work, including a clinical study of renal impairment in healthy volunteers, nonclinical carcinogenicity studies, and nonclinical in vitro drug interaction studies.
Our research and development activities have focused on pimavanserin, trofinetide, ACP-101, ACP-204 and other earlier-stage product candidates. In connection with the FDA approval of DAYBUE, we are required to conduct post-marketing work, including a clinical study of renal impairment in healthy volunteers, nonclinical carcinogenicity studies, and nonclinical in vitro and clinical in vivo drug interaction studies.
In May 2023, we subleased our 2 nd floor of corporate office space in San Diego with a total minimum sublease income of $18.4 million. In addition to operating leases, we enter into certain other long-term commitments for goods and services that are outstanding for periods greater than one year.
As of December 31, 2024 we have long-term contractual obligations related to our operating leases of $59.4 million. In May 2023, we subleased our 2 nd floor of corporate office space in San Diego with a total minimum sublease income of $18.4 million.
As actual costs become known to us, we adjust our accruals. To date, our estimates have not differed materially from the actual costs incurred.
As actual costs become known to us, we adjust our accruals. To date, our estimates have not differed materially from the actual costs incurred. However, subsequent changes in estimates may result in a material change in our accruals, which could also materially affect our balance sheet and results of operations.
We acquired worldwide rights to develop and commercialize ACP-101 with the acquisition of Levo Therapeutics in June 2022. In November 2023, we initiated the Phase 3 COMPASS PWS study evaluating the efficacy and safety of ACP-101 for the treatment of hyperphagia in PWS.
In November 2023, we initiated the Phase 3 COMPASS PWS study evaluating the efficacy and safety of ACP-101 for the treatment of hyperphagia in PWS. Our next most advanced product candidate is ACP-204 for the treatment of ADP.
We have a portfolio of commercial stage products, in-development product opportunities, and research programs that are designed to address significant unmet needs in CNS disorders and rare diseases. In order to achieve significant long-term growth, we will develop our current portfolio, expand our pipeline of early- and late-stage programs through strategic business development, and invest in targeted internal research efforts.
In order to achieve significant long-term growth, we plan to develop our current portfolio, expand our pipeline of early- and late-stage product candidates and expand into areas of rare disease that are adjacent to our existing franchises, including through strategic business development, and make use of our internal capabilities and knowledge.
Similarly, we are unable to estimate with certainty the costs we will incur for post-marketing studies that we committed to conduct in connection with FDA approval of DAYBUE. 65 We expect our research and development expenses will continue to be substantial as we conduct studies pursuant to our post-marketing commitments and pursue the development of pimavanserin for the negative symptoms of schizophrenia and the further development of ACP-101, ACP-204 and other early-stage pipeline programs.
Similarly, we are unable to estimate with certainty the costs we will incur for post-marketing studies that we committed to conduct in connection with FDA approval of DAYBUE.
The nature of the work being conducted under these agreements is such that, in most cases, the services may be stopped on short notice. In such event, we would not be liable for the full amount of the agreement.
Such short-term agreements are generally outstanding for periods less than a year and are settled by cash payments upon delivery of goods and services. The nature of the work being conducted under these agreements is such that, in most cases, the services may be stopped on short notice.
The lengthy process of completing clinical trials and supporting development activities and seeking regulatory approval for our product opportunities requires the expenditure of substantial resources.
We expect our research and development expenses will continue to be substantial as we conduct studies pursuant to our PMRs and pursue the further development of ACP-101, ACP-204 and other early-stage product candidates. The lengthy process of completing clinical trials and supporting development activities and seeking regulatory approval for our product candidates requires the expenditure of substantial resources.
Our commercial portfolio includes two products. In April 2016, the FDA approved NUPLAZID for the treatment of hallucinations and delusions associated with PDP, which is the first and only drug approved in the United States for this condition.
Our neuroscience franchise is anchored by the commercial product NUPLAZID (pimavanserin), which is the first and only drug approved by the FDA for the treatment of hallucinations and delusions associated with PDP. Our neuro-rare disease franchise is anchored by the commercial product DAYBUE, which is the first and only drug approved for the treatment of Rett syndrome.
Cash Flows At December 31, 2023, we had $438.9 million in cash, cash equivalents, and investment securities, compared to $416.8 million at December 31, 2022. This $22.1 million increase in cash, cash equivalents, and investment securities during 2023 was primarily due to net cash provided by operating activities and increased cash proceeds from the exercise of employee stock options.
This $317.1 million increase in cash, cash equivalents, and investment securities during 2024 was primarily due to net cash provided by operating activities, including the sale of the PRV.
Research and Development Expenses Research and development expenses decreased to $351.6 million in 2023, including $17.4 million in stock-based compensation, from $361.6 million in 2022, including $22.6 million in stock-based compensation. The decrease in research and development expenses during 2023 was mainly due to trofinetide commercial supply build that was expensed prior to approval.
The decrease in research and development expenses during 2023 was mainly due to trofinetide commercial supply build that was expensed prior to approval. There was a similar level of clinical spend and business development investment year over year.
Net product sales of DAYBUE were $177.2 million for 2023. There were no net product sales of DAYBUE during 2022.
The increase in net product sales of NUPLAZID of $32.0 million was due to the growth in NUPLAZID unit sales as well as a higher average net selling price in NUPLAZID in 2023 compared to 2022. Net product sales of DAYBUE were $177.2 million for 2023. There were no net product sales of DAYBUE during 2022.
Changes in selling, general and administrative expenses in future periods are subject to the evolving PDP market dynamics, the Rett syndrome market and our further development of pimavanserin in additional indications other than PDP.
Changes in selling, general and administrative expenses in future periods are subject to the evolving PDP market dynamics and the Rett syndrome market. Gain on Sale of Non-Financial Asset Following the FDA approval of DAYBUE, we were granted a Rare Pediatric Disease PRV.
We hold worldwide commercialization rights to pimavanserin. 62 In August 2018, we acquired an exclusive North American license to develop and commercialize DAYBUE for Rett syndrome and other indications from Neuren. Rett syndrome is a debilitating neurological disorder that occurs predominantly in females following apparently normal development for the first six months of life.
Rett syndrome is a debilitating neurological disorder that occurs predominantly in females following apparently normal development for the first six months of life. Rett syndrome also occurs in boys, albeit far less frequently.
The following table provides a summary of activity with respect to our sales allowances and accruals for the year ended December 31, 2022 (in thousands): Distribution Fees, Discounts & Chargebacks Co-Pay Assistance Rebates, Data Fees & Returns Total Balance at December 31, 2021 $ 8,467 $ (202 ) $ 15,717 $ 23,982 Provision related to current period sales 80,836 3,087 51,872 135,795 Credits/payments for current period sales (69,913 ) (3,427 ) (25,826 ) (99,166 ) Credits/payments for prior period sales (8,467 ) 202 (15,717 ) (23,982 ) Balance at December 31, 2022 $ 10,923 $ (340 ) $ 26,046 $ 36,629 69 Cost of Product Sales Cost of product sales was $10.2 million and $19.1 million in 2022 and 2021, respectively, or approximately 2% and 4% of net product sales, respectively.
The following table provides a summary of activity with respect to our sales allowances and accruals for the year ended December 31, 2024 (in thousands): Distribution Fees, Discounts & Chargebacks Co-Pay Assistance Rebates, Data Fees & Returns Total Balance at December 31, 2023 $ 12,156 $ (520 ) $ 86,054 $ 97,690 Provision related to current period sales 122,083 5,148 168,868 296,099 Credits/payments for current period sales (110,200 ) (5,262 ) (20,762 ) (136,224 ) Credits/payments for prior period sales (12,156 ) 520 (86,054 ) (97,690 ) Balance at December 31, 2024 $ 11,883 $ (114 ) $ 148,106 $ 159,875 Cost of Product Sales Cost of product sales was $81.8 million and $41.6 million in 2024 and 2023, respectively, or approximately 9% and 6% of net product sales, respectively.
The increase in selling, general and administrative expenses was primarily due to increased commercial costs associated with the DAYBUE launch, partially offset by reductions in expenses associated with NUPLAZID. Comparison of the Years Ended December 31, 2022 and 2021 Product Sales, Net Product sales, net, comprised of NUPLAZID, were $517.2 million and $484.1 million in 2022 and 2021, respectively.
Comparison of the Years Ended December 31, 2023 and 2022 Product Sales, Net Product sales, net, comprised of NUPLAZID, were $726.4 million and $517.2 million in 2023 and 2022, respectively. Net product sales of NUPLAZID were $549.2 million and $517.2 million in 2023 and 2022, respectively.
The cost of product sales excluding license fees and royalties, as a percentage of net product sales stayed flat during 2022 as compared to 2021.
Cost of product sales as a percentage of net product sales for NUPLAZID remained flat in 2024 as compared to 2023.
We have incurred substantial operating losses since our inception due in large part to expenditures for our research and development activities. As of December 31, 2023, we had an accumulated deficit of approximately $2.4 billion.
We have several product candidates in earlier stages of development for the treatment of CNS disorders and rare diseases, including ACP-711 for the treatment of essential tremor, for which we expect to initiate a Phase 2 study in 2026. 64 We have incurred substantial operating losses since our inception due in large part to expenditures for our research and development activities.
The royalty obligation terminated in October 2021 which was the primary reason for the decrease in cost of product sales during 2022 as compared to 2021. Research and Development Expenses Research and development expenses increased to $361.6 million in 2022, including $22.6 million in stock-based compensation expense, from $239.4 million in 2021, including $22.0 million in stock-based compensation expense.
Subsequent to using our entire zero cost inventories, we estimate our overall cost of product sales as a percentage of total net product sales will be in the range of a mid-single digit to high single digit percentage. 70 Research and Development Expenses Research and development expenses decreased to $351.6 million in 2023, including $17.4 million in stock-based compensation expense, from $361.6 million in 2022, including $22.6 million in stock-based compensation expense.