Biggest changeOur future capital requirements will depend on, and could increase significantly as a result of, many factors, including: • the progress in, and the costs of, our ongoing and planned development activities for pimavanserin, post-marketing studies for NUPLAZID to be conducted over the next several years, and ongoing and planned commercial activities for NUPLAZID; • the costs of our development activities for trofinetide for the treatment of Rett syndrome; • the costs of our development activities for ACP-204 and our other early-stage pipeline programs; • the costs of commercializing NUPLAZID, including the maintenance and development of our sales and marketing capabilities; • the costs of establishing, or contracting for, sales and marketing capabilities for other product candidates; • the amount of U.S. product sales from NUPLAZID; • the costs of preparing applications for regulatory approvals 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 for commercial use in the U.S.; • the costs of manufacturing and distributing trofinetide for potential commercial use in the U.S.; • our ability to obtain regulatory approval for, and subsequently generate product sales from, pimavanserin for the negative symptoms of schizophrenia, from trofinetide for the treatment of Rett syndrome, from ACP-204 and from our other product candidates; • 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 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.
Biggest changeOur 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.
License Fees and Royalties License fees and royalties were $0 and $8.3 million in 2022 and 2021, respectively, and in 2021 include royalties due to the Ipsen Group of two percent of net sales of NUPLAZID and amortization related to the milestone paid to the Ipsen Group upon FDA approval of NUPLAZID in 2016.
License fees and royalties were $0 and $8.3 million in 2022 and 2021, respectively, and in 2021 include royalties due to the Ipsen Group of two percent of net sales of NUPLAZID and amortization related to the milestone paid to the Ipsen Group upon FDA approval of NUPLAZID in 2016.
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 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.
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.
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.”
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
Also included in selling, general and administrative expenses are fees paid to external service providers to support our commercial activities associated with NUPLAZID, 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 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.
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 product revenues, with rates that vary by agreement.
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.
To date, our estimates have not differed 60 materially from the actual chargebacks and organization fees. 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.
To date, our estimates have not differed materially from the actual chargebacks and organization fees. 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.
Historically, we have used our internal research and development resources, including our employees and discovery infrastructure, across several projects and many of our costs have not been attributable to a specific project. Accordingly, we have not reported our internal research and development costs on a project basis.
Historically, we have used our internal research and development resources, including our employees and discovery infrastructure, across several projects and many of our costs have not been attributable to a specific project. Accordingly, we have not reported our internal research and development costs on a project-by-project basis.
Selling, General and Administrative Expenses Our selling, general and administrative expenses consist of salaries and other related costs, including stock-based compensation expense, for our commercial personnel, including our specialty sales force, our medical education professionals, and our personnel serving in executive, finance, business development, and business operations functions.
Selling, General and Administrative Expenses Our selling, general and administrative expenses consist of salaries and other related costs, including stock-based compensation expense, for our commercial personnel, including our specialty sales forces, our medical education professionals, and our personnel serving in executive, finance, business development, and business operations functions.
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 our product 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. 66 Product Sales, Net We sell NUPLAZID through SPs and SDs.
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-204, 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 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.
The decrease in net cash provided by financing activities in 2022 relative to 2021 and in 2021 relative to 2020 was primarily due to a decrease in proceeds resulting from the exercise of employee stock options.
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.
Selling, General and Administrative Expenses Selling, general and administrative expenses decreased to $369.1 million in 2022, including $44.5 million in stock-based compensation expense, from $396.0 million in 2021, including $40.4 million in stock-based compensation expense.
Selling, General and Administrative Expenses Selling, general and administrative expenses decreased to $369.1 million in 2022, including $44.5 million in stock-based compensation expense, from $396.0 million in 2021, including $40.3 million in stock-based compensation expense.
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, 2022, we had an accumulated deficit of $2.4 billion.
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.
Our estimates for expected utilization of rebates is based on historical data received from the SPs and SDs since product launch.
Our estimates for expected utilization of rebates is based on historical data received from the SPs, SDs and the single wholesale distributor since product launch.
Such forward-looking statements include statements about the benefits to be derived from NUPLAZID ® (pimavanserin), trofinetide and from our other drug candidates, the potential market opportunities for pimavanserin and our drug candidates, our strategy for the commercialization of NUPLAZID, our plans for exploring and developing pimavanserin for indications other than Parkinson’s disease psychosis, trofinetide as a treatment for Rett syndrome, ACP-204 as a treatment for ADP and our ASO programs, 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 pimavanserin, trofinetide and our other 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.
Such 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.
As of December 31, 2022, we may be required to make milestone payments up to $1.6 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, 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.
We expect that our cash, cash equivalents, and investment securities will be sufficient to fund our planned operations through at least the next 12 months. 63 We may require significant additional financing in the future to fund our operations.
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 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 the extent to which we generate revenue from product sales, our potential approval and commercialization of trofinetide for the treatment of Rett syndrome, our development of pimavanserin for the negative symptoms of schizophrenia, our further development of the early-stage pipeline programs and the progress and timing of expenditures related to studies of NUPLAZID in PDP 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 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.
SPs dispense product to a patient based on the fulfillment of a prescription and SDs sell product to government facilities, long-term care pharmacies, or in-patient hospital pharmacies. Product shipping and handling costs are included in cost of product sales.
SPs dispense product to a patient based on the fulfillment of a prescription and SDs sell product to government facilities, long-term care pharmacies, or in-patient hospital pharmacies. We sell DAYBUE through a single wholesale distributor. Product shipping and handling costs are included in cost of product sales.
Product sales, net for the year ended December 31, 2022 increased as compared to the year ended December 31, 2021 primarily due to a higher average gross selling price of NUPLAZID in 2022 as compared to 2021. 61 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 Cost of Product Sales Cost of product sales was $10.2 million and $10.8 million in 2022 and 2021, respectively, or approximately 2% of product sales, net in both years.
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.
Due to these same factors, we are unable to determine with any certainty the anticipated completion dates for our current research and development programs. Clinical development and regulatory approval timelines, probability of success, and development costs vary widely.
Likewise, we are unable to determine with certainty the anticipated completion dates for our current research and development programs. Clinical development and regulatory approval timelines, probability of success, and development costs vary widely.
The royalty obligation terminated in October 2021 which was the primary reason for the decrease in license fees and royalties 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, from $239.4 million in 2021, including $22.0 million in stock-based compensation.
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.
Financial Operations Overview Product and Collaborative Revenues Product sales, net consist of sales of NUPLAZID, our first and only commercial product to date. 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 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.
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 potential approval and commercialization of trofinetide for the treatment of Rett syndrome.
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.
The cost of product sales as a percentage of product sales, net stayed flat during 2022 as compared to 2021.
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.
We submitted to the FDA an NDA for trofinetide for the 56 treatment of Rett syndrome in July 2022 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.
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.
In addition, we expect to incur increased research and development expenses as a result of advancement of our early-stage development pipeline programs. 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.
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.
Although NUPLAZID was approved by the FDA for the treatment of hallucinations and delusions associated with PDP, 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, to support the potential approval and commercialization of trofinetide for the treatment of Rett syndrome, 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 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.
For example, due to macroeconomic developments, including the Ukraine-Russia conflict, the COVID-19 pandemic and actions taken to slow its spread, 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, 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.
Liquidity and Capital Resources We have funded our operations primarily through sales of our equity securities, payments received under our collaboration agreements, debt financings, interest income, and, since 2016, with revenues from sales of NUPLAZID.
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.
On a long-term basis, we manage future cash requirements relative to our long-term business plans. 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 anticipate that the level of cash used in our operations will fluctuate in future periods depending on the levels of spend for our ongoing and planned commercial activities for NUPLAZID, our potential approval and commercialization of trofinetide for the treatment of Rett syndrome, our ongoing and planned development activities for pimavanserin for the negative symptoms of schizophrenia, studies to be conducted pursuant to our post-marketing commitments, our ongoing and planned development activities for the early-stage pipeline programs and any potential future business development activities.
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 developed and successfully commercialized NUPLAZID (pimavanserin), which was approved by the FDA, in April 2016 for the treatment of hallucinations and delusions associated with PDP, and is the first and only drug approved in the United States for this condition.
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.
Cost of Product Sales Cost of product sales consists of third-party manufacturing costs, freight, and indirect overhead costs associated with sales of NUPLAZID. Cost of product sales may also include period costs related to certain inventory manufacturing services, excess or obsolete inventory adjustment charges, unabsorbed manufacturing and overhead costs, and manufacturing variances.
Cost of product sales may also include period costs related to certain inventory manufacturing services, excess or obsolete inventory adjustment charges, unabsorbed manufacturing and overhead costs, and manufacturing variances. In addition, cost of product sales may include license fees and royalties.
We also may be required to relinquish greater or all rights to product candidates at an earlier stage of development or on less favorable terms than we would otherwise choose.
We also may be required to relinquish greater or all rights to product candidates at an earlier stage of development or on less favorable terms than we would otherwise choose. Additional funding, if obtained, may significantly dilute existing stockholders and could negatively impact the price of our stock.
The decrease in net cash used in operating activities in 2021 relative to 2020 was due to an increase in our net revenues as well as decreased research and development costs and sales and marketing costs .
The increase in net cash provided by operating activities in 2023 relative to 2022 was primarily due to an increase in our net revenues and decreased research and development costs , partially offset by increased sales and marketing costs .
We expect our research and development expenses 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 trofinetide for the treatment of Rett syndrome as well as the further development of 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. 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.
To the extent these long-term commitments are noncancelable, they are reflected in the above table. 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 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.
Net cash provided by investing activities totaled $73.2 million in 2022 compared to net cash used in investing activities of $71.1 million in 2021 and net cash provided by investing activities of $192.5 million in 2020. 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. The increase in net cash provided by investing activities in 2022 compared to 2021 was primarily due to increased net maturities of investment securities.
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.
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.
We cannot predict with certainty what the full impact that macroeconomic developments, including the ongoing conflict between Ukraine and Russia and the COVID-19 pandemic, 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.
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.
Changes in selling, general and administrative expenses in future periods are subject to the evolving PDP market dynamics, the regulatory and approval processes of trofinetide and our further development of pimavanserin in additional indications other than PDP. 59 Critical Accounting Policies and Estimates A summary of the significant accounting policies is provided in Note 2 to our Consolidated Financial Statements.
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.
Our research and development activities have focused on pimavanserin, trofinetide, ACP-204 and other early-stage programs. We currently are responsible for all costs incurred in the ongoing development of pimavanserin and we expect to continue to make substantial investments in clinical studies of pimavanserin for the treatment of the negative symptoms of schizophrenia.
We charge all research and development expenses to operations as incurred. Our research and development activities have focused on pimavanserin, trofinetide, ACP-101, ACP-204 and other early-stage programs. We currently are responsible for all costs incurred in the ongoing development of pimavanserin. In connection with the FDA approval of NUPLAZID, we committed to conduct four post-marketing studies.
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.
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.
To the extent that external expenses are not attributable to a specific project, they are included in other early-stage programs. 58 The following table summarizes our research and development expenses for the years ended December 31, 2022, 2021, and 2020 (in thousands): Years Ended December 31, 2022 2021 2020 Costs of external service providers: NUPLAZID (pimavanserin) $ 62,746 $ 73,696 $ 96,705 Trofinetide 62,300 39,814 47,614 Early stage programs 64,786 35,964 14,691 Upfront and milestone payments* 88,741 10,999 72,666 Subtotal 278,573 160,473 231,676 Internal costs 60,422 56,973 56,140 Stock-based compensation 22,580 21,969 31,314 Total research and development expenses $ 361,575 $ 239,415 $ 319,130 _____________________ * Includes upfront and milestone consideration as well as transaction costs associated with acquired in-process research and development.
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.
The increase in net cash used in investing activities in 2021 compared to 2020 was primarily due to increased net purchases of investment securities. Net cash provided by financing activities decreased to $8.2 million in 2022 compared to $18.2 million in 2021 and $81.0 million in 2020.
Net cash provided by financing activities increased to $25.1 million in 2023 compared to $8.2 million in 2022 and $18.2 million in 2021. 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.
License Fees and Royalties License fees and royalties consist of milestone payments expensed or capitalized and subsequently amortized under our 2006 license agreement with the Ipsen Group. License fees and royalties also include royalties of 2% due to the Ipsen Group based upon net sales of NUPLAZID. This obligation terminated in October 2021.
License fees and royalties currently consist of milestone payments capitalized and subsequently amortized under our 2018 license agreement with Neuren. License fees and royalties also include royalties of tiered, escalating, double-digit percentages due to Neuren based upon net sales of DAYBUE.
The cost of product sales as a percentage of product sales, net stayed flat during 2021 as compared to 2020.
Cost of product sales as a percentage of net product sales for NUPLAZID remains flat in 2023 as compared to 2022.
We also make investments in our office and laboratory facilities to enable continued expansion of our business.
We also make investments in our office and laboratory facilities to enable continued expansion of our business. 71 As of December 31, 2023 we have long-term contractual obligations related to our operating leases of $66.5 million.
This $103.9 million decrease in cash, cash equivalents, and investment securities during 2022 was primarily due to net cash used in operating activities, offset in part by cash proceeds from the exercise of employee stock options. 65 Net cash used in operating activities decreased to $114.0 million in 2022 compared to $125.7 million in 2021 and $136.2 million in 2020.
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.
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 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.
Material Cash Requirements Our material cash requirements in the short and long term consist of the operational, manufacturing, and capital expenditures, a portion of which contain contractual or other obligations. We plan to fund our material cash requirements with our current financial resources together with our anticipated receipts from product sales.
We plan to fund our material cash requirements with our current financial resources together with our anticipated receipts from product sales. On a long-term basis, we manage future cash requirements relative to our long-term business plans.
Our investment policy defines allowable investments and establishes guidelines relating to credit quality, diversification, and maturities of our investments to preserve principal and maintain liquidity. All investment securities have a credit rating of at least Aa3/AA- or better, or P-1/A-1 or better, as determined by Moody’s Investors Service or Standard & Poor’s.
All investment securities have a credit rating of at least Aa3/AA- or better, or P-1/A-1 or better, as determined by Moody’s Investors Service or Standard & Poor’s. Our investment portfolio has not been adversely impacted by the disruptions in the credit markets that have occurred in the past.
We acquired an exclusive North American license to develop and commercialize trofinetide for Rett syndrome and other indications from Neuren in August of 2018.
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.
We project completing the enrollment this year with top-line results in early 2024. In addition, we recently announced that we are developing an internally discovered new molecule, ACP-204, which builds upon the learnings of pimavanserin in the treatment of neuropsychiatric symptoms, and is currently being evaluated in a Phase 1 clinical program.
In addition, in August 2022 we announced that we are developing an internally discovered new molecule, ACP-204, which builds upon the learnings of pimavanserin in the treatment of neuropsychiatric symptoms. We completed Phase 1 study of ACP-204 which demonstrated a favorable safety and tolerability profile, and supports its target product profile as a potential treatment for ADP.
Our investment portfolio has not been adversely impacted by the disruptions in the credit markets that have occurred in the past. However, if there are future disruptions in the credit markets, there can be no assurance that our investment portfolio will not be adversely affected .
However, if there are future disruptions in the credit markets, there can be no assurance that our investment portfolio will not be adversely affected. Material Cash Requirements Our material cash requirements in the short and long term consist of the operational, manufacturing, and capital expenditures, a portion of which contain contractual or other obligations.
Product sales, net for the year ended December 31, 2021 increased as compared to the year ended December 31, 2020 primarily due to a higher average gross selling price of NUPLAZID in 2021 as compared to 2020 as well as the growth in NUPLAZID unit sales of approximately 3% in 2021 as compared to 2020. 62 The following table provides a summary of activity with respect to our sales allowances and accruals for the year ended December 31, 2021 (in thousands): Distribution Fees, Discounts & Chargebacks Co-Pay Assistance Rebates, Data Fees & Returns Total Balance at December 31, 2020 $ 4,221 $ (152 ) $ 14,116 $ 18,185 Provision related to current period sales 72,011 1,794 40,490 114,295 Credits/payments for current period sales (63,544 ) (1,996 ) (24,773 ) (90,313 ) Credits/payments for prior period sales (4,221 ) 152 (14,116 ) (18,185 ) Balance at December 31, 2021 $ 8,467 $ (202 ) $ 15,717 $ 23,982 Cost of Product Sales Cost of product sales was $10.8 million and $10.2 million in 2021 and 2020, respectively, or approximately 2% of product sales, net in both years.
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.
NUPLAZID is a selective serotonin inverse agonist/antagonist, preferentially targeting 5-HT 2A receptors with no appreciable affinity for dopaminergic, histaminergic, or muscarinic receptors. Through this novel mechanism, NUPLAZID demonstrated significant efficacy in reducing the hallucinations and delusions associated with PDP without negatively impacting motor function in our Phase 3 pivotal trial.
Through this novel mechanism, NUPLAZID demonstrated significant efficacy in reducing the hallucinations and delusions associated with PDP without negatively impacting motor function in our Phase 3 pivotal trial. NUPLAZID has the potential to avoid many of the debilitating side effects of existing antipsychotics, none of which are approved by the FDA for the treatment of PDP.
Upon completion of our Phase 1 work, we plan to initiate studies evaluating various doses of ACP-204 in patients with Alzheimer’s disease psychosis. 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. ACP-204 is a new chemical entity for which we hold the worldwide rights.
The following is a summary of our long-term contractual obligations as of December 31, 2022 (in thousands): Total Less than 1 Year 1-3 Years 3-5 Years More than 5 Years Operating leases $ 73,391 $ 9,562 $ 18,304 $ 16,838 $ 28,687 Other long-term contractual obligations 2,000 1,000 1,000 — — Total $ 75,391 $ 10,562 $ 19,304 $ 16,838 $ 28,687 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.
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.
Selling, General and Administrative Expenses Selling, general and administrative expenses increased to $396.0 million in 2021, including $40.4 million in stock-based compensation expense, from $388.7 million in 2020, including $50.5 million in stock-based compensation expense.
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.
Additional funding, if obtained, may significantly dilute existing stockholders and could negatively impact the price of our stock. 64 We have invested a substantial portion of our available cash in money market funds, U.S. treasury notes, and high quality, marketable debt instruments of corporations and government sponsored enterprises in accordance with our investment policy.
We have invested a substantial portion of our available cash in money market funds, municipal bonds, and government sponsored enterprises in accordance with our investment policy. Our investment policy defines allowable investments and establishes guidelines relating to credit quality, diversification, and maturities of our investments to preserve principal and maintain liquidity.