Organization and Accounting Pronouncements	6 Months Ended
Jun. 30, 2025
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and Accounting Pronouncements	1. Organization and Accounting Pronouncements Description of Business Equillium, Inc., together with its wholly owned subsidiaries (the Company), was incorporated in the state of Delaware on March 16, 2017. The Company is a biotechnology innovator developing novel therapies to treat severe autoimmune and inflammatory disorders with the mission to develop life-changing therapeutics for patients. The Company's primary goal is to advance EQ504, its novel aryl hydrocarbon receptor modulator, into and through clinical development. The Company is headquartered in La Jolla, California, and it manages its business as one operating segment. Refer to Note 5 for additional information. Liquidity and Business Risks As of June 30, 2025, the Company had $11.5 million in cash and cash equivalents. From inception through June 30, 2025, substantially all of the Company’s efforts have been focused on research, development and the advancement of the Company’s clinical and pre-clinical product candidates. During the second quarter of 2025 the Company paused its research and development activities for all programs pending the Company's ability to raise capital in the immediate term. The Company has not yet generated product sales and as a result has incurred significant operating losses and negative cash flows from operations. As a result, the Company has an accumulated deficit of $208.2 million as of June 30, 2025. The Company expects to incur additional losses in the future to conduct research and development for which it will need to raise additional capital to implement. The Company's limited cash and cash equivalents previously raised substantial doubt about the Company's ability to continue as a going concern. Subsequent to June 30, 2025, the Company completed an equity financing with gross proceeds of approximately $30 million with the ability to raise an additional $20 million subject to achieving certain clinical and pricing related milestones. Refer to Note 11 for additional information. Based on the Company’s current operating plan, management believes that the $30 million raised together with the existing cash and cash equivalents as of June 30, 2025 will be sufficient to fund operations for at least the next 12 months from the date this Quarterly Report on Form 10-Q is filed with the Securities and Exchange Commission (SEC). Accordingly, management has concluded that substantial doubt regarding the Company’s ability to continue as a going concern has been alleviated. Basis of Presentation The accompanying condensed consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles (GAAP) and the rules and regulations of the SEC related to a quarterly report on Form 10-Q. Any reference in these notes to applicable guidance is meant to refer to GAAP as found in the Accounting Standards Codification (ASC) and Accounting Standards Updates (ASU) promulgated by the Financial Accounting Standards Board (FASB). Certain information and note disclosures normally included in annual financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to those rules and regulations. The condensed consolidated financial statements reflect all adjustments which, in the opinion of management, are necessary for a fair statement of the results for the periods presented. All such adjustments are of a normal and recurring nature. The operating results presented in these condensed consolidated financial statements are not necessarily indicative of the results that may be expected for any future periods. These condensed consolidated financial statements should be read in conjunction with the audited financial statements and the notes thereto for the year ended December 31, 2024 included in the Company’s Annual Report on Form 10-K filed with the SEC on March 27, 2025. Principles of Consolidation The accompanying condensed consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries. All intercompany transactions and balances have been eliminated in consolidation. Foreign Currency Translation The Company’s wholly-owned subsidiary in Australia uses its local currency as its functional currency. Assets and liabilities are translated into U.S. dollars at quarter-end exchange rates and revenues and expenses are translated at average exchange rates during the quarter and year-to-date periods. Foreign currency translation adjustments for the reported periods are included in accumulated other comprehensive income, net in the Company’s condensed consolidated statements of comprehensive loss, and the cumulative effect is included in the stockholders’ equity section of the Company’s condensed consolidated balance sheets. Recently Issued Accounting Pronouncements In December 2023, the FASB issued ASU 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures. ASU 2023-09 requires annual disclosures of specific categories in the rate reconciliation, additional information for reconciling items that meet a quantitative threshold and a disaggregation of income taxes paid, net of refunds. ASU 2023-09 also eliminates certain existing disclosure requirements related to uncertain tax positions and unrecognized deferred tax liabilities. ASU 2023-09 is effective for the Company beginning with the Company's Annual Report on Form 10-K for the year ending December 31, 2025. Early adoption is permitted. ASU 2023-09 should be applied prospectively. Retrospective adoption is permitted. The Company is currently assessing the impact this standard will have on the Company’s consolidated financial statement disclosures. In November 2024, the FASB issued ASU 2024-03, Income Statement - Reporting Comprehensive Income - Expense Disaggregation Disclosures (Subtopic 220-40): Disaggregation of Income Statement Expenses, to improve disclosures around an entity's expenses. Upon adoption, companies will be required to disclose in the notes to the financial statements a disaggregation of certain expense categories included within the expense captions on the face of the income statement. The standard is effective for annual reporting periods beginning after December 15, 2026 and interim periods beginning after December 15, 2027, with early adoption permitted, and can be applied either prospectively or retrospectively. The Company plans to adopt the standard in its 2027 annual period and is currently assessing the impact this standard will have on the Company's consolidated financial statement disclosures. No other new accounting pronouncements or legislation issued or effective as of June 30, 2025 have had, or are expected to have, a material impact on the Company’s condensed consolidated financial statements.

Equillium, Inc., together with its wholly owned subsidiaries (the Company), was incorporated in the state of Delaware on March 16, 2017.

The Company is a biotechnology innovator developing novel therapies to treat severe autoimmune and inflammatory disorders with the mission to develop life-changing therapeutics for patients. The Company's primary goal is to advance EQ504, its novel aryl hydrocarbon receptor modulator, into and through clinical development.

The Company is headquartered in La Jolla, California, and it manages its business as one operating segment. Refer to Note 5 for additional information.

As of June 30, 2025, the Company had $11.5 million in cash and cash equivalents. From inception through June 30, 2025, substantially all of the Company’s efforts have been focused on research, development and the advancement of the Company’s clinical and pre-clinical product candidates. During the second quarter of 2025 the Company paused its research and development activities for all programs pending the Company's ability to raise capital in the immediate term. The Company has not yet generated product sales and as a result has incurred significant operating losses and negative cash flows from operations. As a result, the Company has an accumulated deficit of $208.2 million as of June 30, 2025. The Company expects to incur additional losses in the future to conduct research and development for which it will need to raise additional capital to implement.

The Company's limited cash and cash equivalents previously raised substantial doubt about the Company's ability to continue as a going concern. Subsequent to June 30, 2025, the Company completed an equity financing with gross proceeds of approximately $30 million with the ability to raise an additional $20 million subject to achieving certain clinical and pricing related milestones. Refer to Note 11 for additional information. Based on the Company’s current operating plan, management believes that the $30 million raised together with the existing cash and cash equivalents as of June 30, 2025 will be sufficient to fund operations for at least the next 12 months from the date this Quarterly Report on Form 10-Q is filed with the Securities and Exchange Commission (SEC). Accordingly, management has concluded that substantial doubt regarding the Company’s ability to continue as a going concern has been alleviated.

The accompanying condensed consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles (GAAP) and the rules and regulations of the SEC related to a quarterly report on Form 10-Q. Any reference in these notes to applicable guidance is meant to refer to GAAP as found in the Accounting Standards Codification (ASC) and Accounting Standards Updates (ASU) promulgated by the Financial Accounting Standards Board (FASB). Certain information and note disclosures normally included in annual financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to those rules and regulations. The condensed consolidated financial statements reflect all adjustments which, in the opinion of management, are necessary for a fair statement of the results for the periods presented. All such adjustments are of a normal and recurring nature. The operating results presented in these condensed consolidated financial statements are not necessarily indicative of the results that may be expected for any future periods. These condensed consolidated financial statements should be read in conjunction with the audited financial statements and the notes thereto for the year ended December 31, 2024 included in the Company’s Annual Report on Form 10-K filed with the SEC on March 27, 2025.

The accompanying condensed consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries. All intercompany transactions and balances have been eliminated in consolidation.

The Company’s wholly-owned subsidiary in Australia uses its local currency as its functional currency. Assets and liabilities are translated into U.S. dollars at quarter-end exchange rates and revenues and expenses are translated at average exchange rates during the quarter and year-to-date periods. Foreign currency translation adjustments for the reported periods are included in accumulated other comprehensive income, net in the Company’s condensed consolidated statements of comprehensive loss, and the cumulative effect is included in the stockholders’ equity section of the Company’s condensed consolidated balance sheets.

Recently Issued Accounting Pronouncements

In December 2023, the FASB issued ASU 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures. ASU 2023-09 requires annual disclosures of specific categories in the rate reconciliation, additional information for reconciling items that meet a quantitative threshold and a disaggregation of income taxes paid, net of refunds. ASU 2023-09 also eliminates certain existing disclosure requirements related to uncertain tax positions and unrecognized deferred tax liabilities. ASU 2023-09 is effective for the Company beginning with the Company's Annual Report on Form 10-K for the year ending December 31, 2025. Early adoption is permitted. ASU 2023-09 should be applied prospectively. Retrospective adoption is permitted. The Company is currently assessing the impact this standard will have on the Company’s consolidated financial statement disclosures.

In November 2024, the FASB issued ASU 2024-03, Income Statement - Reporting Comprehensive Income - Expense Disaggregation Disclosures (Subtopic 220-40): Disaggregation of Income Statement Expenses, to improve disclosures around an entity's expenses. Upon adoption, companies will be required to disclose in the notes to the financial statements a disaggregation of certain expense categories included within the expense captions on the face of the income statement. The standard is effective for annual reporting periods beginning after December 15, 2026 and interim periods beginning after December 15, 2027, with early adoption permitted, and can be applied either prospectively or retrospectively. The Company plans to adopt the standard in its 2027 annual period and is currently assessing the impact this standard will have on the Company's consolidated financial statement disclosures.

No other new accounting pronouncements or legislation issued or effective as of June 30, 2025 have had, or are expected to have, a material impact on the Company’s condensed consolidated financial statements.