Summary of Significant Accounting Policies	3 Months Ended
Mar. 31, 2018
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	1. Summary of Significant Accounting Policies Description of Business Mateon Therapeutics, Inc. (“Mateon” or the “Company”) is a clinical-stage biopharmaceutical company developing drugs for the treatment of orphan oncology indications, with programs in acute myeloid leukemia (“AML”) and immuno-oncology. Basis of Presentation The accompanying unaudited condensed financial statements have been prepared in accordance with U.S. generally accepted accounting principles for interim financial information and with the instructions to Form 10-Q and Article 10 of Regulation S-X. The financial statements do not include all of the information and footnotes required by U.S. generally accepted accounting principles for complete financial statements. In the opinion of management, however, all adjustments (consisting only of normal recurring adjustments) considered necessary for a fair presentation have been included. Operating results for the three months ended March 31, 2018 are not necessarily indicative of the results that may be expected for any other interim period or for the year ending December 31, 2018. The balance sheet at December 31, 2017 has been derived from the audited financial statements at that date but does not include all of the information and footnotes required by U.S. generally accepted accounting principles for complete financial statements. For further information, refer to the financial statements and footnotes thereto included in the Annual Report on Form 10-K for the Company for the year ended December 31, 2017. Use of Estimates The preparation of financial statements in conformity with U.S. generally accepted accounting principles requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of income and expenses during the reporting period. Actual results could differ from those estimates. Cash Equivalents Highly liquid investments with original maturities of three months or less at the date of purchase are considered to be cash equivalents. Cash equivalents are stated at fair value. Going Concern Evaluation The Company has experienced net losses every year since inception and, as of March 31, 2018, had an accumulated deficit of approximately $293 million. The Company has no source of revenue and does not expect to receive any product revenue in the near future. The Company expects to incur significant additional operating losses over at least the next several years, principally as a result of the Company’s continuing clinical trials for its investigational drugs. The principal source of the Company’s working capital to date has been the proceeds from the sale of equity. As of March 31, 2018, the Company had $0.2 million in cash and current liabilities of $1.5 million. Following the receipt of an estimated $2.4 million in net proceeds from a financing transaction in April 2018, based on the Company’s planned operations, the Company’s management expects Mateon’s existing cash to support its planned operations into the fourth quarter of 2018. Prior to this time, the Company will need to secure additional funding or could be forced to curtail or terminate operations. Because the Company does not currently have a guaranteed source of working capital that will sustain planned operations past the fourth quarter of 2018, Management has determined that there is substantial doubt about the Company’s ability to continue as a going concern. The Company will need to raise capital in order to fund its planned operations beyond this time. If the Company is unable to access additional funds when needed, it may not be able to continue the development of its investigational drugs and the Company could be required to delay, scale back or eliminate some or all of its development programs and other operations. Any additional equity financing, if available to the Company, may not be available on favorable terms, would most likely be dilutive to its current stockholders and debt financing, if available, may involve restrictive covenants. If the Company accesses funds through collaborative or licensing arrangements, it may be required to relinquish rights to some of its technologies or product candidates that it would otherwise seek to develop or commercialize on its own, on terms that are not favorable to the Company. The Company’s ability to access capital when needed is not assured and, if not achieved on a timely basis, will materially harm its business, financial condition and results of operations. Recent Accounting Pronouncements In February 2016, the FASB issued ASU No. 2016-2, “Leases (Topic 842),” which requires substantially all leases, including operating leases, to be recognized by lessees on their balance sheet as a right-of-use asset and corresponding lease liability. This ASU is effective for the Company’s interim and annual reporting periods beginning January 1, 2019 and early adoption is permitted. The Company is currently evaluating the impact that the adoption of this ASU will have on its financial statements. In August 2016, the FASB issued ASU No. 2016-15 “Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments,” which addresses several cash flow issues that diversify in practice. The new guidance is effective for fiscal years beginning after December 15, 2017 and for interim periods within those years. The Company adopted this ASU as of January 1, 2018, and its adoption did not have a material impact on the Company’s financial statements.

1. Summary of Significant Accounting Policies

Description of Business

Mateon Therapeutics, Inc. (“Mateon” or the “Company”) is a clinical-stage biopharmaceutical company developing drugs for the treatment of orphan oncology indications, with programs in acute myeloid leukemia (“AML”) and immuno-oncology.

Basis of Presentation

The accompanying unaudited condensed financial statements have been prepared in accordance with U.S. generally accepted accounting principles for interim financial information and with the instructions to Form 10-Q and Article 10 of Regulation S-X. The financial statements do not include all of the information and footnotes required by U.S. generally accepted accounting principles for complete financial statements. In the opinion of management, however, all adjustments (consisting only of normal recurring adjustments) considered necessary for a fair presentation have been included. Operating results for the three months ended March 31, 2018 are not necessarily indicative of the results that may be expected for any other interim period or for the year ending December 31, 2018.

The balance sheet at December 31, 2017 has been derived from the audited financial statements at that date but does not include all of the information and footnotes required by U.S. generally accepted accounting principles for complete financial statements. For further information, refer to the financial statements and footnotes thereto included in the Annual Report on Form 10-K for the Company for the year ended December 31, 2017.

Use of Estimates

The preparation of financial statements in conformity with U.S. generally accepted accounting principles requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of income and expenses during the reporting period. Actual results could differ from those estimates.

Cash Equivalents

Highly liquid investments with original maturities of three months or less at the date of purchase are considered to be cash equivalents. Cash equivalents are stated at fair value.

Going Concern Evaluation

The Company has experienced net losses every year since inception and, as of March 31, 2018, had an accumulated deficit of approximately $293 million. The Company has no source of revenue and does not expect to receive any product revenue in the near future. The Company expects to incur significant additional operating losses over at least the next several years, principally as a result of the Company’s continuing clinical trials for its investigational drugs. The principal source of the Company’s working capital to date has been the proceeds from the sale of equity. As of March 31, 2018, the Company had $0.2 million in cash and current liabilities of $1.5 million. Following the receipt of an estimated $2.4 million in net proceeds from a financing transaction in April 2018, based on the Company’s planned operations, the Company’s management expects Mateon’s existing cash to support its planned operations into the fourth quarter of 2018. Prior to this time, the Company will need to secure additional funding or could be forced to curtail or terminate operations. Because the Company does not currently have a guaranteed source of working capital that will sustain planned operations past the fourth quarter of 2018, Management has determined that there is substantial doubt about the Company’s ability to continue as a going concern. The Company will need to raise capital in order to fund its planned operations beyond this time. If the Company is unable to access additional funds when needed, it may not be able to continue the development of its investigational drugs and the Company could be required to delay, scale back or eliminate some or all of its development programs and other operations. Any additional equity financing, if available to the Company, may not be available on favorable terms, would most likely be dilutive to its current stockholders and debt financing, if available, may involve restrictive covenants. If the Company accesses funds through collaborative or licensing arrangements, it may be required to relinquish rights to some of its technologies or product candidates that it would otherwise seek to develop or commercialize on its own, on terms that are not favorable to the Company. The Company’s ability to access capital when needed is not assured and, if not achieved on a timely basis, will materially harm its business, financial condition and results of operations.

Recent Accounting Pronouncements

In February 2016, the FASB issued ASU No. 2016-2, “Leases (Topic 842),” which requires substantially all leases, including operating leases, to be recognized by lessees on their balance sheet as a right-of-use asset and corresponding lease liability. This ASU is effective for the Company’s interim and annual reporting periods beginning January 1, 2019 and early adoption is permitted. The Company is currently evaluating the impact that the adoption of this ASU will have on its financial statements.

In August 2016, the FASB issued ASU No. 2016-15 “Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments,” which addresses several cash flow issues that diversify in practice. The new guidance is effective for fiscal years beginning after December 15, 2017 and for interim periods within those years. The Company adopted this ASU as of January 1, 2018, and its adoption did not have a material impact on the Company’s financial statements.