Acumen Pharmaceuticals, Inc.

Previous wording

We are a clinical-stage biopharmaceutical company developing a novel disease-modifying approach to target what we believe to be a key underlying cause of Alzheimer’s disease, or AD. Alzheimer’s disease is a progressive neurodegenerative disease of the brain that leads to loss of memory and cognitive functions and ultimately results in death. Our scientific founders pioneered research on soluble amyloid-beta oligomers, or AßOs, which are globular assemblies of the amyloid-beta, or Aß, peptide that are distinct from Aß monomers and amyloid plaques. Based on decades of research and supporting evidence, AßOs have gained increasing scientific acceptance as a primary toxin involved in the initiation and propagation of AD pathology. We are currently focused on advancing a targeted immunotherapy drug candidate, sabirnetug, in our Phase 2 ALTITUDE-AD clinical trial following Phase 1 results in “early AD” patients (patients with mild cognitive impairment or mild dementia due to AD) that were reported in July 2023. Sabirnetug is a recombinant humanized immunoglobulin gamma 2, or IgG2, monoclonal antibody, or mAb, that was designed to selectively target AßOs. In addition, we are investigating a subcutaneous dosing option of sabirnetug, as well as a blood-brain barrier-penetrating, oligomer-targeted Enhanced Brain Delivery (EBDTM) therapy for AD.

Current wording

We are a clinical-stage biopharmaceutical company developing a novel disease-modifying approach to target what we believe to be a key underlying cause of Alzheimer’s disease, or AD. Alzheimer’s disease is a progressive neurodegenerative disease of the brain that leads to loss of memory and cognitive functions and ultimately results in death. Our scientific founders pioneered research on soluble amyloid-beta oligomers, or AßOs, which are globular assemblies of the amyloid-beta, or Aß, peptide that are distinct from Aß monomers and amyloid plaques. Based on decades of research and supporting evidence, AßOs have gained increasing scientific acceptance as a primary toxin involved in the initiation and propagation of AD pathology. We are currently focused on advancing a targeted immunotherapy drug candidate, sabirnetug, in our Phase 2 ALTITUDE-AD clinical trial. We completed enrollment in March 2025 and expect to announce top-line results for ALTITUDE-AD in late 2026. ALTITUDE-AD is a randomized, double-blind, placebo-controlled, three-arm clinical trial designed to evaluate the clinical efficacy, safety and tolerability of sabirnetug with up to 180 participants per arm for a total of 542 participants with mild cognitive impairment or mild dementia due to AD. We plan to use the Integrated Alzheimer’s Disease Rating Scale at 18 months as the primary outcome measure. The active doses for ALTITUDE-AD are 35 mg/kg and 50 mg/kg, dosed intravenously every four weeks. These dose levels and frequency were selected based on extensive pharmacokinetic and pharmacodynamic modeling of our Phase 1 INTERCEPT-AD clinical trial of sabirnetug. Sabirnetug is a recombinant humanized immunoglobulin gamma 2, or IgG2, monoclonal antibody, or mAb, that was designed to selectively target AßOs. In July 2023, we announced topline results from INTERCEPT-AD, which demonstrated that sabirnetug met the primary and secondary objectives of this clinical trial in 62 participants with early AD.

Previous wording

In July 2025, we entered into a collaboration, option and license agreement with JCR Pharmaceuticals, or JCR, to develop an oligomer-targeted Enhanced Brain Delivery, or EBDTM, therapy for AD. Under the terms of the agreement, in addition to an upfront payment that JCR received, if we exercise our exclusive option to develop up to two development candidates, JCR will be eligible for an additional option payment of $9.25 million. Our option can be exercised when there is a preclinical candidate data package, inclusive of a non-human primate study, which is expected in early 2026. JCR will also be eligible to receive future milestone payments of up to $40 million related to development, and up to $515 million related to sales, for a total of up to $555 million, as well as single-digit percentage royalties on sales of any products that emerge from the collaboration. The combination of sabirnetug or additional, novel, AβO-selective antibodies with JCR’s blood-brain barrier-penetrating technology, J-Brain Cargo®, strengthens Acumen’s portfolio of AβO-targeted therapies. The partnership is designed to advance potential next-generation treatment options for people living with AD, by targeting the development of products with enhanced efficacy, safety and convenience.

Current wording

In July 2025, we entered into a collaboration, option and license agreement with JCR Pharmaceuticals Co. Ltd., or JCR, to develop an Aß oligomer-targeted EBDTM therapy for AD. Under the terms of the agreement, in addition to an upfront license payment that we paid to JCR, if we exercise our exclusive option to develop up to two development candidates, JCR will be eligible for an option exercise payment of $9.25 million. Our option can be exercised when there is a preclinical candidate data package, inclusive of a non-human primate study, which is expected in early 2026. JCR will also be eligible to receive future milestone payments of up to $40 million related to development, and up to $515 million related to sales, for a total of up to $555 million, as well as single-digit percentage royalties on sales of any products that emerge from the collaboration. The combination of sabirnetug or additional, novel, AβO-selective antibodies with JCR’s blood-brain barrier-penetrating technology, J-Brain Cargo®, strengthens Acumen’s portfolio of AβO-targeted therapies. The partnership is designed to advance potential next-generation treatment options for people living with AD, by targeting the development of products with enhanced efficacy, safety and convenience.

Previous wording

During the six months ended June 30, 2025, no shares of common stock were issued under our at-the-market offering program, or the ATM. In January 2024, we issued 2,068,246 shares of our common stock under the ATM, for net proceeds of $7.9 million, or $3.84 per share.

Current wording

During the nine months ended September 30, 2025, no shares of common stock were issued under our at-the-market offering program, or the ATM. In January 2024, we issued 2,068,246 shares of our common stock under the ATM, for net proceeds of $7.9 million, or $3.84 per share.

Previous wording

We have incurred net losses and negative cash flows from operations since our inception. Our net losses were $69.7 million and $35.4 million for the six months ended June 30, 2025 and 2024, respectively. Approximately $62.4 million, or 89%, of the net loss for the six months ended June 30, 2025 was due to research and development spending. As of June 30, 2025, we had an accumulated deficit of $394.9 million. Our net losses and cash flows from operations may fluctuate significantly from quarter-to-quarter and year-to-year, depending on the timing of nonclinical studies, clinical trials and our expenditures on other research and development activities. We expect our expenses and operating losses will increase substantially for the foreseeable future as we advance sabirnetug in clinical development, seek to expand our product candidate portfolio through developing additional product candidates, and incur additional costs associated with operating as a public company. It is likely that we will seek third-party collaborators for the future commercialization of sabirnetug or any other product candidate that is approved for marketing. Should we seek to commercialize our products at our own expense, we would incur significant additional expenses for marketing, sales, manufacturing and distribution. We will not generate revenue from product sales unless and until we successfully complete clinical development and obtain regulatory approval for our product candidates.

Current wording

We have incurred net losses and negative cash flows from operations since our inception. Our net losses were $96.2 million and $65.2 million for the nine months ended September 30, 2025 and 2024, respectively. Approximately $84.4 million, or 88%, of the net loss for the nine months ended September 30, 2025 was due to research and development spending. As of September 30, 2025, we had an accumulated deficit of $421.3 million. Our net losses and cash flows from operations may fluctuate significantly from quarter-to-quarter and year-to-year, depending on the timing of nonclinical studies, clinical trials and our expenditures on other research and development activities. We expect our expenses and operating losses will increase substantially for the foreseeable future as we advance sabirnetug in clinical development, seek to expand our product candidate portfolio through developing additional product candidates, and incur additional costs associated with operating as a public company. It is likely that we will seek third-party collaborators for the future commercialization of sabirnetug or any other product candidate that is approved for marketing. Should we seek to commercialize our products at our own expense, we would incur significant additional expenses for marketing, sales, manufacturing and distribution. We will not generate revenue from product sales unless and until we successfully complete clinical development and obtain regulatory approval for our product candidates.

Previous wording

As of June 30, 2025, we had cash and cash equivalents andmarketable securities of $166.2 million; included in this amount is the first tranche of $30.0 million that we received under our Loan Agreement, which was received on November 10, 2023. Based on our current operating plan, we expect that our existing cash and cash equivalents and marketable securities will be sufficient to enable us to fund our oper ating expenses and capital expenditure requirements into early 2027. We have based this estimate on assumptions that may prove to be wrong, and we could exhaust our available capital resources sooner than we expect, including based on our decision to initiate other clinical trials or programs. See “Liquidity and Capital Resources.”

Current wording

As of September 30, 2025, we had cash and cash equivalents andmarketable securities of $136.1 million; included in this amount is the first tranche of $30.0 million that we received under our Loan Agreement, which was received on November 10, 2023. Based on our current operating plan, we expect that our existing cash and cash equivalents and marketable securities will be sufficient to enable us to fund our oper ating expenses and capital expenditure requirements into early 2027. We have based this estimate on assumptions that may prove to be wrong, and we could exhaust our available capital resources sooner than we expect, including based on our decision to initiate other clinical trials or programs. See “Liquidity and Capital Resources.”

Previous wording

•consulting and professional fees related to research and development activities, including stock-based compensation to non-employees;

Current wording

•consulting and professional fees related to research and development activities, including noncash stock-based compensation to non-employees;

Previous wording

•employee-related expenses, including salaries, benefits and stock-based compensation expenses for our research and development personnel.

Current wording

•employee-related expenses, including salaries, benefits and noncash stock-based compensation expenses for our research and development personnel.

Previous wording

As we currently only have one product candidate, sabirnetug, in clinical development, we do not separately track expenses by program. Further, we have historically relied primarily on consultants for research and development activities; our internal research and development personnel costs currently represent approximately 14% of our total research and development expenses. Our research and development expenses increased substantially since initiating the clinical trial program for sabirnetug in 2021. We expect that our research and development expenses will continue to increase substantially in connection with our continued clinical development activities for sabirnetug.

Current wording

As we currently only have one product candidate, sabirnetug, in clinical development, we do not separately track expenses by program. Further, we have historically relied primarily on consultants for research and development activities; our internal research and development personnel costs currently represent approximately 15% of our total research and development expenses. Our research and development expenses increased substantially since initiating the clinical trial program for sabirnetug in 2021. We expect that our research and development expenses will continue to increase substantially in connection with our continued clinical development activities for sabirnetug.

Previous wording

General and administrative expenses consist primarily of employee-related expenses, including stock-based compensation costs, as well as business insurance, management and business consultants and other related costs. General and administrative expenses also include professional fees for legal, consulting, accounting, auditing, tax and patent services, investor and public relations, board of directors’ expenses, information technology, franchise taxes, rent, travel expenses and subscriptions.

Current wording

General and administrative expenses consist primarily of employee-related expenses, including noncash stock-based compensation costs, as well as business insurance, management and business consultants and other related costs. General and administrative expenses also include professional fees for legal, consulting, accounting, auditing, tax and patent services, investor and public relations, board of directors’ expenses, information technology, franchise taxes, rent, travel expenses and subscriptions.

Previous wording

We expect that our general and administrative expenses will increase as our organization and headcount required in the future grows to support continued research and development activities and potential commercialization of our product candidates. These increases will likely include increased costs related to the hiring of additional personnel and fees incurred for outside consultants, attorneys and accountants, among other expenses. Additionally, we expect to continue to incur significant expenses associated with being a public company, including costs of additional personnel, accounting, audit, legal, regulatory and tax-related services associated with maintaining compliance with exchange listing and Securities and Exchange Commission, or SEC, requirements, director and officer insurance costs, and investor and public relations costs.

Current wording

We expect that our general and administrative expenses will remain consistent for the foreseeable future and may increase as our organization and headcount required in the future grows to support continued research and development activities and potential commercialization of our product candidates. These increases will likely include increased costs related to the hiring of additional personnel and fees incurred for outside consultants, attorneys and accountants, among other expenses. Additionally, we expect to continue to incur significant expenses associated with being a public company, including costs of additional personnel, accounting, audit, legal, regulatory and tax-related services associated with maintaining compliance with exchange listing and Securities and Exchange Commission, or SEC, requirements, director and officer insurance costs, and investor and public relations costs.

Previous wording

Research and development expenses were $37.1 million and $19.5 million for the three months ended June 30, 2025 and 2024, respectively. The$17.6 million increase was primarily due to a $14.8 million increase for manufacturing and materials and a $4.5 million increase for CRO costs mainly related to investigator grant expenses associated with the ALTITUDE-AD clinical trial, for which we completed enrollment in March 2025 following dosing of the first patient in May 2024. Additionally, we incurred a $0.7 million increase for personnel-related costs. These increases were partially offset by decreases of $1.7 million for license agreement expenses and $0.7 million for other clinical research expenses, including assay development.

Current wording

Research and development expenses were $22.0 million and $27.2 million for the three months ended September 30, 2025 and 2024, respectively. The $5.2 million decrease was primarily due to a reduction of $4.4 million for CRO costs associated with the ALTITUDE-AD clinical trial, for which we completed enrollment in March 2025 following dosing of the first patient in May 2024. Additionally, we incurred reduced expenses of $2.5 million for license agreements and $0.6 million related to services provided by research and development consultants and contractors. Partially offsetting these decreased expenses were increases of $1.0 million for manufacturing and materials costs associated with our ALTITUDE-AD clinical trial, $0.7 million for other clinical trial expenses and $0.6 million for personnel-related costs.

Previous wording

Other income was $2.4 million and $6.7 million for the six months ended June 30, 2025 and 2024, respectively. The$4.3 million decrease was primarily attributable to a $3.3 million decrease in interest income on our portfolio of marketable securities due to both lower interest rates and a lower average investment balance during the six months ended June 30, 2025 with the utilization of cash from investment maturities supporting our ongoing operating cash needs. Additionally, there were decreases in change in fair value of our embedded derivatives related to our Loan Agreement of$0.9 million and other expense, net of $0.1 million.

Current wording

Other income was $0.1 million and $2.5 million for the three months ended September 30, 2025 and 2024, respectively. The $2.4 million decrease was primarily attributable to a $1.9 million decrease in interest income on our portfolio of marketable securities due primarily to a lower average investment balance during the three months ended September 30, 2025 with the utilization of cash from investment maturities supporting our ongoing operating cash needs. Additionally, there were increased expenses associated with the change in fair value of our embedded derivatives related to our Loan Agreement of $0.4 million and other expense, net of $0.1 million.

Previous wording

The following table summarizes our results of operations for the six months ended June 30, 2025 and 2024 (in thousands):

Current wording

The following table summarizes our results of operations for the nine months ended September 30, 2025 and 2024 (in thousands):

Previous wording

Research and development expenses were $62.4 million and $32.0 million for the six months ended June 30, 2025 and 2024, respectively. The $30.4 million increase was prim arily due to a $19.4 million increase for manufacturing and materials and an $11.5 million increase for CRO costs mainly related to investigator grant expenses associated with the ALTITUDE-AD clinical trial, for which we completed enrollment in March 2025 following dosing of the first patient in May 2024. Additionally, we incurred a $1.7 million increase for personnel-related costs, a $0.7 million increase for other research expenses and a $0.4 million increase for shipping, packaging and storage costs. These increases were partially offset by decreases in the following: $1.7 million for license agreement expenses, $0.9 million related to services provided by research and development consultants and contractors, and $0.7 million for other clinical trial expenses.

Current wording

Research and development expenses were $84.4 million and $59.2 million for the nine months ended September 30, 2025 and 2024, respectively. The $25.2 million increase was primarily due to a $20.5 million increase for manufacturing and materials mainly associated with our ALTITUDE-AD clinical trial, as well as a $7.1 million increase for total CRO costs driven mainly by increased investigator grant expenses for ALTITUDE-AD, for which we completed enrollment in March 2025 following dosing of the first patient in May 2024. Additionally, we incurred a $2.3 million increase for personnel-related costs, a $0.7 million increase for other research expenses, a $0.4 million increase for other clinical trial expenses, a $0.4 million increase for shipping, packaging and storage costs and other immaterial increases totaling approximately $0.4 million. These increased expenses were partially offset by decreases of $4.2 million for license agreement expenses, $1.5 million for costs related to services provided by research and development consultants and contractors and $0.9 million for clinical assay development.

Previous wording

Other income was $0.8 million and $3.8 million for the three months ended June 30, 2025 and 2024, respectively. The$3.0 million decrease was primarily attributable toa $1.8 million decrease in interest incomeon our portfolio of marketable securities due to both lower interest rates and a lower average investment balance during the three months ended June 30, 2025 with the utilization of cash from investment maturities supporting our ongoing operating cash needs. Additionally, there were decreases in change in fair value of our embedded derivatives related to our Loan Agreement of$1.1 million and other expense, net of $0.1 million.

Current wording

Other income was $2.4 million and $9.2 million for the nine months ended September 30, 2025 and 2024, respectively. The $6.8 million decrease was primarily attributable to a $5.2 million decrease in interest income on our portfolio of marketable securities due primarily to a lower average investment balance during the nine months ended September 30, 2025 with the utilization of cash from investment maturities supporting our ongoing operating cash needs. Additionally, there were increased expenses associated with the change in fair value of our embedded derivatives related to our Loan Agreement of $1.3 million and other expense, net of $0.2 million.

Previous wording

During the six months ended June 30, 2025, no shares of common stock were issued under our ATM. In January 2024, we issued 2,068,246 shares of common stock under the ATM for net proceeds of $7.9 million, or $3.84 per share.

Current wording

During the nine months ended September 30, 2025, no shares of common stock were issued under our ATM. In January 2024, we issued 2,068,246 shares of common stock under the ATM for net proceeds of $7.9 million, or $3.84 per share.

Previous wording

As of June 30, 2025, we had cash and cash equivalents andmarketable securities totaling $166.2 million. Ouravailable-for-sale marketable securities mature within two years. Based on our current operating plan, we expect that our existing cash and cash equivalents and marketable securities will be sufficient to enable us to fund our operating expenses and capital expenditure requirements into early 2027. We have based this estimate on assumptions that may prove to be wrong, and we could exhaust our available capital resources sooner than we expect, including based on our decision to initiate other clinical trials or programs.

Current wording

As of September 30, 2025, we had cash and cash equivalents andmarketable securities totaling $136.1 million. Ouravailable-for-sale marketable securities mature within 15 months. Based on our current operating plan, we expect that our existing cash and cash equivalents and marketable securities will be sufficient to enable us to fund our operating expenses and capital expenditure requirements into early 2027. We have based this estimate on assumptions that may prove to be wrong, and we could exhaust our available capital resources sooner than we expect, including based on our decision to initiate other clinical trials or programs.

Previous wording

Net cash used in operating activities increased by $31.6 million to $66.0 million for the six months ended June 30, 2025 from $34.4 million for the six months ended June 30, 2024. The$34.3 million increase in net loss for the six months ended June 30, 2025, adjusted for a decrease in non-cash income for amortization and accretion on marketable securities of $2.6 million and a decrease in the change in fair value of embedded derivatives of $0.9 million accounted for a $30.8 million increase in cash used in operating activities as compared to the six months ended June 30, 2024. Working capital changes contributed $0.8 million of additional cash used in operations, including increases in cash used for accounts payable and accrued clinical trial expenses of $6.4 million and $6.9 million, respectively, which were mostly offset by cash provided from accrued expenses and other liabilities of $7.4 million and $5.1 million from prepaid expenses and other current assets.

Current wording

Net cash used in operating activities increased by $37.4 million to $96.4 million for the nine months ended September 30, 2025 from $59.0 million for the nine months ended September 30, 2024. The $31.0 million increase in net loss for the nine months ended September 30, 2025, adjusted for a decrease in noncash income for amortization and accretion on marketable securities of $3.7 million and a decrease in the change in fair value of embedded derivatives of $1.3 million accounted for a $26.0 million increase in cash used in operating activities as compared to the nine months ended September 30, 2024. Working capital changes contributed $11.5 million of additional cash used in operations, including increases in cash used for accounts payable and accrued clinical trial expenses of $5.9 million and $13.6 million, respectively, which were partially offset by cash provided from prepaid expenses and other current assets of $5.4 million and $2.6 million from accrued expenses and other liabilities.

Previous wording

Cash provided by investing activities during the six months ended June 30, 2025 of $67.2 million increasedby $38.7 million from cash used in investing activities of $28.5 million during the six months ended June 30, 2024, primarily due to an increase in proceeds from maturities of marketable securities of $19.7 million, as well as a decrease in purchases of marketable securities of $19.0 million.

Current wording

Cash provided by investing activities during the nine months ended September 30, 2025 of $107.7 million increasedby $89.3 million from cash provided by investing activities of $18.4 million during the nine months ended September 30, 2024, primarily due to a decrease in purchases of marketable securities of $117.6 million, which was partially offset by a decrease in proceeds from maturities and sales of marketable securities of $28.2 million and a $0.1 million increase in purchases of property and equipment.

Previous wording

Cash provided by financing activities during the six months ended June 30, 2025 was immaterial and decreased by $7.0 million from cash provided by financing activities of $7.0 million during the six months ended June 30, 2024. Cash provided by financing activities during the six months ended June 30, 2024 was primarilydue to net proceeds of $7.9 million from the issuance of common stock under our ATM, partially offset by $0.7 million for payment under a finance lease agreement for certain computer equipment for our Phase 2 ALTITUDE-AD clinical trial.

Current wording

Cash provided by financing activities during the nine months ended September 30, 2025 decreased by $7.0 million from cash provided by financing activities of $6.9 million during the nine months ended September 30, 2024. Cash provided by financing activities during the nine months ended September 30, 2024 was primarilydue to net proceeds of $7.9 million from the issuance of common stock under our ATM, partially offset by $0.7 million for payment under a finance lease agreement for certain computer equipment for our Phase 2 ALTITUDE-AD clinical trial and $0.2 million for payments related to deferred offering costs.

Previous wording

A description of our significant accounting policies is included in our Annual Report on Form 10-K. Please read the unaudited condensed financial statements in conjunction with our audited financial statements and accompanying notes in our Annual Report on Form 10-K.

Current wording

A description of our significant accounting policies is included in our Annual Report on Form 10-K. Please read the unaudited condensed financial statements and notes included in this Quarterly Report on Form 10-Q in conjunction with our audited financial statements and accompanying notes in our Annual Report on Form 10-K.