Description of Business and Organization	12 Months Ended
Dec. 31, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Description of Business and Basis of Presentation	1. Description of Business and Basis of Presentation Larimar Therapeutics, Inc., together with its subsidiary (the “Company” or “Larimar”), is a clinical-stage biotechnology company focused on developing treatments for patients suffering from complex rare diseases using its novel cell penetrating peptide technology platform. Larimar's lead product candidate, nomlabofusp (nomlabofusp is the International Nonproprietary Name ("INN") and the United States Adopted Name ("USAN") for CTI-1601), is a subcutaneously administered, recombinant fusion protein intended to deliver human frataxin ("FXN"), an essential protein, to the mitochondria of patients with Friedreich’s ataxia ("FA"). FA is a rare, progressive and fatal disease in which patients are unable to produce sufficient FXN due to a genetic abnormality. The Company has completed two phase 1 studies of nomlabofusp and a Phase 2 dose exploration study in patients with FA. In May 2021, after reporting positive top-line data from the Company’s Phase 1 FA program, the U.S. Food and Drug Administration (“FDA”) placed a clinical hold on the Company’s nomlabofusp clinical program after the Company notified the FDA of mortalities at the highest dose levels of a 26-week non-human primate toxicology study that was designed to support extended dosing of patients with nomlabofusp. In August 2022, the Company submitted a complete response to the clinical hold following a Type C Meeting with the FDA, and proposed as nomlabofusp's next clinical trial a Phase 2, four-week, dose exploration study in FA patients starting at the lower dose levels tested in the Company’s Phase 1 multiple-ascending dose clinical trial. In September 2022, the FDA lifted its full clinical hold on the nomlabofusp program and imposed a partial clinical hold. In May 2023, the Company announced top-line data from its completed 25 mg cohort of a Phase 2, four-week, dose exploration trial of nomlabofusp in patients with FA and provided a complete response to the FDA in June 2023, which included unblinded safety, pharmacokinetic ("PK"), and pharmacodynamic ("PD") data from the Phase 2 trial’s completed 25 mg cohort. Data from the completed 25 mg cohort (n = 13) indicated that nomlabofusp was generally well tolerated and showed increases in FXN levels from baseline compared to placebo in all evaluated tissues (skin and buccal cells) at day 14 (the final day of daily dosing in the trial). In June 2023, the Company met with the FDA. Following that meeting, the Company submitted a complete response to the FDA’s partial clinical hold that included unblinded safety, PK and frataxin data from the Phase 2 trial’s completed 25 mg cohort. In July 2023, following the FDA’s review of the Company's complete response to the partial clinical hold, the FDA cleared initiation of a second cohort at 50 mg of our four-week, placebo-controlled, Phase 2 dose exploration trial and initiation of the OLE trial with daily dosing of 25 mg. In February 2024, the Company reported positive top-line data and successful completion of their four-week, placebo-controlled Phase 2 dose exploration study of nomlabofusp in participants with FA. Nomlabofusp was generally well tolerated and demonstrated dose dependent increases in FXN levels in all evaluated tissues (skin and buccal cells) after daily dosing of 14 days followed by every other day dosing until day 28 in the 25 mg and 50 mg cohorts. Participants in the 25 mg (n=13) and 50 mg (n=15) cohorts were randomized 2:1 to receive subcutaneous injections of nomlabofusp or placebo. The initiation of additional U.S. clinical trials evaluating nomlabofusp are contingent on FDA review of data under the partial clinical hold. In January 2024, the Company initiated an OLE trial evaluating daily subcutaneous injections of 25 mg of nomlabofusp self-administered or administered by a caregiver, with the first patient dosed in March 2024. Participants who complete treatment in the Phase 2 dose exploration trial, or who previously completed a prior clinical trial of nomlabofusp are potentially eligible to screen for the OLE. The OLE will evaluate the safety, tolerability and PK and measures of frataxin levels in peripheral tissues as well as other exploratory PD (lipid profiles and gene expression data) following long-term subcutaneous administration of nomlabofusp. Clinical measures collected during the trial will be compared to data from a synthetic control arm derived from participants in the Friedreich’s Ataxia Clinical Outcome Measures Study (FACOMS) database. Dose escalation in the OLE trial will be considered based on safety, tolerability, PK, and tissue FXN levels from the Phase 2 trial’s 50 mg cohort as well as available data from the 25 mg dose of nomlabofusp in the OLE trial and is contingent on FDA review as part of the partial clinical hold. Initial data from the OLE trial is expected in the fourth quarter of 2024. The Company is subject to risks and uncertainties common to pre-commercial companies in the biotechnology industry, including, but not limited to, development and commercialization by competitors of new technological innovations, dependence on key personnel, protection of proprietary technology, compliance with governmental regulations, failure to secure regulatory approval for its drug candidates or any other product candidates and the ability to secure additional capital to fund its operations. Product candidates under development will require extensive non-clinical and clinical testing and regulatory approval prior to commercialization. These efforts require significant amounts of additional capital, adequate personnel, infrastructure and extensive compliance-reporting capabilities. Even if the Company's drug development efforts are successful, it is uncertain when, if ever, it will realize significant revenue from product sales. Basis of Presentation The consolidated financial statements include the accounts of Larimar and its wholly owned subsidiary. All intercompany balances and transactions have been eliminated. The accompanying consolidated financial statements have been prepared in conformity with GAAP. Liquidity and Capital Resources The Company’s consolidated financial statements have been presented on the basis that it will continue as a going concern, which contemplates the realization of assets and satisfaction of liabilities in the normal course of business. Since its inception, the Company has incurred significant recurring operating losses and negative cash flows from operations. The Company has incurred net losses of $36.9 million and $35.4 million for the years ended December 31, 2023, and 2022, respectively. In addition, as of December 31, 2023, the Company had an accumulated deficit of $188.6 million. The Company expects to continue to generate operating losses for the foreseeable future. As of December 31, 2023, the Company had approximately $86.8 million of cash, cash equivalents and marketable securities available for use to fund its operations and capital requirements. The Company has funded its operations to date primarily with proceeds from sales of common stock and proceeds from the sale of prefunded warrants for the purchase of common stock, the acquisition in 2020 of cash, cash equivalents and marketable securities upon the merger with Zafgen, Inc. ("Zafgen") and, prior to the 2020 merger with Zafgen, capital contributions from Chondrial Holdings, LLC. In February 2024, the Company sold 19,736,842 shares of its common stock in an underwritten public offering at a price of $8.74 per share and received net proceeds of approximately $161.6 million. In accordance with Accounting Standards Update (“ASU”) No. 2014-15, "Disclosure of Uncertainties about an Entity’s Ability to Continue as a Going Concern", the Company has evaluated whether there are certain conditions and events, considered in the aggregate, that raise substantial doubt about the Company’s ability to continue as a going concern within one year after the date that these consolidated financial statements are issued. As of the issuance date of these consolidated financial statements, the Company expects its cash, cash equivalents and marketable securities, including its net proceeds from the February 2024 public offering, will be sufficient to fund its forecasted operating expenses and capital expenditure requirements into 2026. If the timing of the Company's clinical assumptions are delayed or if there are other forecasted assumption changes that negatively impact its operating plan, the Company would reduce expenditures in order to further extend cash resources. The Company has not yet commercialized any products and does not expect to generate revenue from the commercial sale of any products for several years, if at all. The Company expects that its research and development and general and administrative expenses will continue to increase and, as a result, that it will need additional capital to fund its future operating and capital requirements. Unless and until the Company can generate substantial revenue, management continuously evaluates different strategies to obtain the required funding for future operations. These strategies include seeking additional funding through a combination of public or private equity offerings, debt or royalty financings, collaborations and licensing arrangements, strategic partnerships with pharmaceutical and/or larger biotechnology companies, or other sources. The incurrence of indebtedness would result in increased fixed payment obligations and the Company may be required to agree to certain restrictive covenants, such as limitations on its ability to incur additional debt, limitations on its ability to acquire, sell or license intellectual property rights, minimum required cash balances and other operating restrictions that could adversely impact the Company's ability to conduct its business. Any additional fundraising efforts may divert the Company's management from their day-to-day activities, which may adversely affect its ability to develop and commercialize its product candidates. There can be no assurance that the Company will be able to raise sufficient additional capital on acceptable terms, if at all. If such additional financing is not available on satisfactory terms, or is not available in sufficient amounts, or if the Company does not have sufficient authorized shares, the Company may be required to delay, limit, or eliminate the development of business opportunities and its ability to achieve its business objectives, its competitiveness, and its business, financial condition, and results of operations will be materially adversely affected. The Company could also be required to seek funds through arrangements with collaborative partners or otherwise at an earlier stage than otherwise would be desirable and it may be required to relinquish rights to some of its technologies or product candidates or otherwise agree to terms unfavorable to it, any of which may have a material adverse effect on the Company's business, operating results and prospects. In addition, geopolitical tensions, volatility of capital markets, and other adverse macroeconomic events, including those due to inflationary pressures, rising interest rates, bank instability and the ability of the U.S. government to manage federal debt limits as well as the potential impact of other health crises on the global financial markets may reduce the Company's ability to access capital, which could negatively affect its liquidity and ability to continue as a going concern. If the Company is unable to obtain sufficient funding when needed and/or on acceptable terms, the Company may be required to significantly curtail, delay or discontinue one or more of its research and development programs, the manufacture of clinical and commercial supplies, product portfolio expansion, pre commercialization efforts and/or commercial operations, which could adversely affect its business prospects, or the Company may be unable to continue operations.

Larimar Therapeutics, Inc., together with its subsidiary (the “Company” or “Larimar”), is a clinical-stage biotechnology company focused on developing treatments for patients suffering from complex rare diseases using its novel cell penetrating peptide technology platform. Larimar's lead product candidate, nomlabofusp (nomlabofusp is the International Nonproprietary Name ("INN") and the United States Adopted Name ("USAN") for CTI-1601), is a subcutaneously administered, recombinant fusion protein intended to deliver human frataxin ("FXN"), an essential protein, to the mitochondria of patients with Friedreich’s ataxia ("FA"). FA is a rare, progressive and fatal disease in which patients are unable to produce sufficient FXN due to a genetic abnormality.

The Company has completed two phase 1 studies of nomlabofusp and a Phase 2 dose exploration study in patients with FA.

In May 2021, after reporting positive top-line data from the Company’s Phase 1 FA program, the U.S. Food and Drug Administration (“FDA”) placed a clinical hold on the Company’s nomlabofusp clinical program after the Company notified the FDA of mortalities at the highest dose levels of a 26-week non-human primate toxicology study that was designed to support extended dosing of patients with nomlabofusp. In August 2022, the Company submitted a complete response to the clinical hold following a Type C Meeting with the FDA, and proposed as nomlabofusp's next clinical trial a Phase 2, four-week, dose exploration study in FA patients starting at the lower dose levels tested in the Company’s Phase 1 multiple-ascending dose clinical trial. In September 2022, the FDA lifted its full clinical hold on the nomlabofusp program and imposed a partial clinical hold.

In May 2023, the Company announced top-line data from its completed 25 mg cohort of a Phase 2, four-week, dose exploration trial of nomlabofusp in patients with FA and provided a complete response to the FDA in June 2023, which included unblinded safety, pharmacokinetic ("PK"), and pharmacodynamic ("PD") data from the Phase 2 trial’s completed 25 mg cohort. Data from the completed 25 mg cohort (n = 13) indicated that nomlabofusp was generally well tolerated and showed increases in FXN levels from baseline compared to placebo in all evaluated tissues (skin and buccal cells) at day 14 (the final day of daily dosing in the trial).

In June 2023, the Company met with the FDA. Following that meeting, the Company submitted a complete response to the FDA’s partial clinical hold that included unblinded safety, PK and frataxin data from the Phase 2 trial’s completed 25 mg cohort.

In July 2023, following the FDA’s review of the Company's complete response to the partial clinical hold, the FDA cleared initiation of a second cohort at 50 mg of our four-week, placebo-controlled, Phase 2 dose exploration trial and initiation of the OLE trial with daily dosing of 25 mg.

In February 2024, the Company reported positive top-line data and successful completion of their four-week, placebo-controlled Phase 2 dose exploration study of nomlabofusp in participants with FA. Nomlabofusp was generally well tolerated and demonstrated dose dependent increases in FXN levels in all evaluated tissues (skin and buccal cells) after daily dosing of 14 days followed by every other day dosing until day 28 in the 25 mg and 50 mg cohorts. Participants in the 25 mg (n=13) and 50 mg (n=15) cohorts were randomized 2:1 to receive subcutaneous injections of nomlabofusp or placebo. The initiation of additional U.S. clinical trials evaluating nomlabofusp are contingent on FDA review of data under the partial clinical hold.

In January 2024, the Company initiated an OLE trial evaluating daily subcutaneous injections of 25 mg of nomlabofusp self-administered or administered by a caregiver, with the first patient dosed in March 2024. Participants who complete treatment in the Phase 2 dose exploration trial, or who previously completed a prior clinical trial of nomlabofusp are potentially eligible to screen for the OLE. The OLE will evaluate the safety, tolerability and PK and measures of frataxin levels in peripheral tissues as well as other exploratory PD (lipid profiles and gene expression data) following long-term subcutaneous administration of nomlabofusp. Clinical measures collected during the trial will be compared to data from a synthetic control arm derived from participants in the Friedreich’s Ataxia Clinical Outcome Measures Study (FACOMS) database. Dose escalation in the OLE trial will be considered based on safety, tolerability, PK, and tissue FXN levels from the Phase 2 trial’s 50 mg cohort as well as available data from the 25 mg dose of nomlabofusp in the OLE trial and is contingent on FDA review as part of the partial clinical hold. Initial data from the OLE trial is expected in the fourth quarter of 2024.

The Company is subject to risks and uncertainties common to pre-commercial companies in the biotechnology industry, including, but not limited to, development and commercialization by competitors of new technological innovations, dependence on key personnel, protection of proprietary technology, compliance with governmental

regulations, failure to secure regulatory approval for its drug candidates or any other product candidates and the ability to secure additional capital to fund its operations. Product candidates under development will require extensive non-clinical and clinical testing and regulatory approval prior to commercialization. These efforts require significant amounts of additional capital, adequate personnel, infrastructure and extensive compliance-reporting capabilities. Even if the Company's drug development efforts are successful, it is uncertain when, if ever, it will realize significant revenue from product sales.

Liquidity and Capital Resources

The Company’s consolidated financial statements have been presented on the basis that it will continue as a going concern, which contemplates the realization of assets and satisfaction of liabilities in the normal course of business.

Since its inception, the Company has incurred significant recurring operating losses and negative cash flows from operations. The Company has incurred net losses of $36.9 million and $35.4 million for the years ended December 31, 2023, and 2022, respectively. In addition, as of December 31, 2023, the Company had an accumulated deficit of $188.6 million. The Company expects to continue to generate operating losses for the foreseeable future. As of December 31, 2023, the Company had approximately $86.8 million of cash, cash equivalents and marketable securities available for use to fund its operations and capital requirements.

The Company has funded its operations to date primarily with proceeds from sales of common stock and proceeds from the sale of prefunded warrants for the purchase of common stock, the acquisition in 2020 of cash, cash equivalents and marketable securities upon the merger with Zafgen, Inc. ("Zafgen") and, prior to the 2020 merger with Zafgen, capital contributions from Chondrial Holdings, LLC.

In February 2024, the Company sold 19,736,842 shares of its common stock in an underwritten public offering at a price of $8.74 per share and received net proceeds of approximately $161.6 million.

In accordance with Accounting Standards Update (“ASU”) No. 2014-15, "Disclosure of Uncertainties about an Entity’s Ability to Continue as a Going Concern", the Company has evaluated whether there are certain conditions and events, considered in the aggregate, that raise substantial doubt about the Company’s ability to continue as a going concern within one year after the date that these consolidated financial statements are issued. As of the issuance date of these consolidated financial statements, the Company expects its cash, cash equivalents and marketable securities, including its net proceeds from the February 2024 public offering, will be sufficient to fund its forecasted operating expenses and capital expenditure requirements into 2026. If the timing of the Company's clinical assumptions are delayed or if there are other forecasted assumption changes that negatively impact its operating plan, the Company would reduce expenditures in order to further extend cash resources.

The Company has not yet commercialized any products and does not expect to generate revenue from the commercial sale of any products for several years, if at all. The Company expects that its research and development and general and administrative expenses will continue to increase and, as a result, that it will need additional capital to fund its future operating and capital requirements. Unless and until the Company can generate substantial revenue, management continuously evaluates different strategies to obtain the required funding for future operations. These strategies include seeking additional funding through a combination of public or private equity offerings, debt or royalty financings, collaborations and licensing arrangements, strategic partnerships with pharmaceutical and/or larger biotechnology companies, or other sources. The incurrence of indebtedness would result in increased fixed payment obligations and the Company may be required to agree to certain restrictive covenants, such as limitations on its ability to incur additional debt, limitations on its ability to acquire, sell or license intellectual property rights, minimum required cash balances and other operating restrictions that could adversely impact the Company's ability to conduct its business. Any additional fundraising efforts may divert the Company's management from their day-to-day activities, which may adversely affect its ability to develop and commercialize its product candidates.

There can be no assurance that the Company will be able to raise sufficient additional capital on acceptable terms, if at all. If such additional financing is not available on satisfactory terms, or is not available in sufficient amounts, or if the Company does not have sufficient authorized shares, the Company may be required to delay,

limit, or eliminate the development of business opportunities and its ability to achieve its business objectives, its competitiveness, and its business, financial condition, and results of operations will be materially adversely affected. The Company could also be required to seek funds through arrangements with collaborative partners or otherwise at an earlier stage than otherwise would be desirable and it may be required to relinquish rights to some of its technologies or product candidates or otherwise agree to terms unfavorable to it, any of which may have a material adverse effect on the Company's business, operating results and prospects. In addition, geopolitical tensions, volatility of capital markets, and other adverse macroeconomic events, including those due to inflationary pressures, rising interest rates, bank instability and the ability of the U.S. government to manage federal debt limits as well as the potential impact of other health crises on the global financial markets may reduce the Company's ability to access capital, which could negatively affect its liquidity and ability to continue as a going concern.

If the Company is unable to obtain sufficient funding when needed and/or on acceptable terms, the Company may be required to significantly curtail, delay or discontinue one or more of its research and development programs, the manufacture of clinical and commercial supplies, product portfolio expansion, pre commercialization efforts and/or commercial operations, which could adversely affect its business prospects, or the Company may be unable to continue operations.