Description of Business and Basis of Presentation (Policies)	12 Months Ended
Jun. 30, 2024
Description of Business	Description of Business MEI Pharma, Inc. (Nasdaq: MEIP) is a pharmaceutical company that has been developing novel and differentiated cancer therapies. We built our pipeline by acquiring promising cancer agents and creating value in programs through development, strategic partnerships, and out-licensing or commercialization, as appropriate. Our approach to oncology drug development has been to evaluate our drug candidates in combinations with standard-of-care therapies to overcome known resistance mechanisms and address clear medical needs to provide improved patient benefit. Our pipeline includes voruciclib, an oral cyclin-dependent kinase 9 (CDK9) inhibitor, and ME-344, an intravenous small molecule mitochondrial inhibitor targeting the oxidative phosphorylation pathway.
Basis of Presentation and Consolidation	Basis of Presentation and Consolidation We prepared the consolidated financial statements in accordance with accounting principles generally accepted in the United States (GAAP) and the rules and regulations of the Securities and Exchange Commission (SEC) related to annual reports on Form 10‑K. The accompanying consolidated financial statements include the accounts of MEI Pharma, Inc. and our wholly owned subsidiary, Meadow Merger Sub, Inc. We have eliminated all intercompany accounts and transactions in consolidation. The Company has evaluated subsequent events through the date the consolidated financial statements were issued.
Current Events	Current Events Strategic Alternatives On July 22, 2024, we announced that our Board of Directors (Board) had determined unanimously to begin the evaluation of our strategic alternatives, including potential transactions as well as an orderly wind down of operations, if appropriate, to maximize the value of our assets for our stockholders. We commenced a reduction-in-force beginning August 1, 2024, which will continue in stages as our operational and strategic direction evolves. We have discontinued the clinical development of voruciclib, while certain nonclinical activities related to MEI’s drug candidate assets will continue to be conducted by us. As part of the review of strategic alternatives, we may consider options such as out-licensing opportunities for existing programs and merger and acquisition opportunities. Consistent with our intention to preserve cash, David M. Urso, our President and Chief Executive Officer, and Richard Ghalie, M.D., our Chief Medical Officer, stepped down effective August 1, 2024. Mr. Urso also left the Board at that date. We have entered into consulting agreements with both Mr. Urso and Dr. Ghalie under which they will remain available to assist us in our strategic efforts. Charles V. Baltic III, the Chairperson of the Board, also stepped down from the Board contemporaneously with the announcement on July 22, 2024. Our Board has appointed Justin J. File, our current Chief Financial Officer, to assume the position of Acting Chief Executive Officer and has appointed Frederick W. Driscoll as Chairperson of the Board. Cooperation Agreement On October 31, 2023, we announced our entry into a Cooperation Agreement (Cooperation Agreement) with Anson Funds Management LP and Cable Car Capital LLC (Anson and Cable Car, respectively), which, among other non-financial related items provided for a capital return to stockholders in the form of a dividend in the amount of $1.75 per share of common stock, as further discussed below. Additionally, the Cooperation Agreement contemplated a potential second return of capital not to exceed $9.33 million (Potential Second Return of Capital) if authorized by Board should our ongoing ME-344 Phase 1b trial fail to meet certain defined endpoints or our Board determines not to proceed with a second cohort. As part of the Cooperation Agreement, Anson and Cable Car withdrew their consent solicitation and agreed to abide by customary standstill provisions. Additionally, we reimbursed Anson's and Cable Car’s fees and expenses related to their engagement with us as of the date of the Cooperation Agreement in an amount of $1.1 million, which is recorded within general and administrative expenses in the consolidated statements of operations for the fiscal year ended June 30, 2024. In April 2024, the Board unanimously determined not to proceed with the Potential Second Return of Capital under the Cooperation Agreement in order to conserve resources and align strategic investment, and thereby extend our operational runway. Cash Dividend On November 6, 2023, pursuant to the Cooperation Agreement, the Board declared a special cash dividend of $1.75 per share of common stock to stockholders of record at the close of business on November 17, 2023. The total dividend of $11.7 million was paid on December 6, 2023, and was recorded as a reduction of additional paid-in capital in the consolidated statements of stockholders' equity, as we have an accumulated deficit, rather than retained earnings. Infinity Merger In February 2023, we, Infinity Pharmaceuticals, Inc. (Infinity), and Meadow Merger Sub, Inc., our wholly owned subsidiary (Merger Sub) entered into an agreement and plan of merger (Merger Agreement). The Merger Agreement provided that Merger Sub will merge with and into Infinity, with Infinity being the surviving entity as a wholly owned subsidiary of us (transaction referred to as the Merger) and was subject to approvals by our and Infinity’s stockholders, respectively. On July 23, 2023, we convened our Special Meeting of Stockholders at which time our stockholders did not approve the proposed transaction and subsequently, we delivered a letter to Infinity which terminated the Merger Agreement pursuant to Section 7.2(c) of the Merger Agreement, effective July 23, 2023. KKC Termination Agreement In November 2022, we and Kyowa Kirin Co., Ltd. (KKC) met with the U.S. Food and Drug Administration (FDA) in a follow-up meeting to the March 2022 end of Phase 2 meeting related to zandelisib. At this meeting, the FDA provided further guidance regarding the design and statistical analysis for the COASTAL trial. Following the November meeting, the companies jointly concluded that a clinical trial consistent with the recent FDA guidance, including modification of the ongoing COASTAL trial, would likely not be feasible to complete within a time period that would support further investment or with sufficient certainty of the regulatory requirements for approval to justify continued global development efforts. As a result, we and KKC jointly decided to discontinue global development of zandelisib for indolent forms of non-Hodgkin lymphoma outside of Japan. The discontinuation of zandelisib development outside of Japan was a business decision based on the regulatory guidance from the FDA and was not related to the zandelisib clinical data generated to date. Although KKC continued certain ongoing Japanese clinical trials at that time, in May 2023 KKC decided to discontinue development of zandelisib in Japan after meeting with the Pharmaceuticals and Medical Devices Agency (PMDA), concluding that conducting a randomized study consistent with agency guidance to support a marketing application would likely not be feasible to complete within a time period that would support further investment. Due to KKC’s decision to discontinue development of zandelisib in Japan, as well as the prior joint decision to discontinue zandelisib development outside of Japan, on July 14, 2023, the parties entered into a Termination Agreement to mutually terminate the global License, Development and Commercialization Agreement executed in April 2020.
Liquidity	Liquidity We have accumulated losses of $388.2 million since inception and expect to incur operating losses and generate negative cash flows from operations for the foreseeable future. As of June 30, 2024, we had $38.3 million in cash, cash equivalents and short-term investments. In connection with our July 2024 announcement regarding the evaluation of our strategic alternatives, we have discontinued the clinical development of voruciclib, while certain nonclinical research and development activities continue. As a result, we will continue to incur research and development expenses in connection with clinical trial closing costs and the completion of our nonclinical projects. We believe that our cash balance, including our short-term investments, will be sufficient to meet our obligations and fund operations for at least the next 12 months from the issuance of these consolidated financial statements. To date, we have obtained cash and funded our operations primarily through equity financings and license agreements and to continue the development of our drug candidates, we would require one or more capital transactions, whether through the sale of equity securities, debt financing, license agreements or entry into strategic partnerships at some point in the future. There can be no assurance that we will be able to continue to raise additional capital in the future.

Description of Business and Basis of Presentation (Policies)

12 Months Ended

Jun. 30, 2024

MEI Pharma, Inc. (Nasdaq: MEIP) is a pharmaceutical company that has been developing novel and differentiated cancer therapies. We built our pipeline by acquiring promising cancer agents and creating value in programs through development, strategic partnerships, and out-licensing or commercialization, as appropriate. Our approach to oncology drug development has been to evaluate our drug candidates in combinations with standard-of-care therapies to overcome known resistance mechanisms and address clear medical needs to provide improved patient benefit. Our pipeline includes voruciclib, an oral cyclin-dependent kinase 9 (CDK9) inhibitor, and ME-344, an intravenous small molecule mitochondrial inhibitor targeting the oxidative phosphorylation pathway.

Basis of Presentation and Consolidation

We prepared the consolidated financial statements in accordance with accounting principles generally accepted in the United States (GAAP) and the rules and regulations of the Securities and Exchange Commission (SEC) related to annual reports on Form 10‑K. The accompanying consolidated financial statements include the accounts of MEI Pharma, Inc. and our wholly owned subsidiary, Meadow Merger Sub, Inc. We have eliminated all intercompany accounts and transactions in consolidation.

The Company has evaluated subsequent events through the date the consolidated financial statements were issued.

Current Events

Strategic Alternatives

On July 22, 2024, we announced that our Board of Directors (Board) had determined unanimously to begin the evaluation of our strategic alternatives, including potential transactions as well as an orderly wind down of operations, if appropriate, to maximize the value of our assets for our stockholders. We commenced a reduction-in-force beginning August 1, 2024, which will continue in stages as our operational and strategic direction evolves. We have discontinued the clinical development of voruciclib, while certain nonclinical activities related to MEI’s drug candidate assets will continue to be conducted by us. As part of the review of strategic alternatives, we may consider options such as out-licensing opportunities for existing programs and merger and acquisition opportunities.

Consistent with our intention to preserve cash, David M. Urso, our President and Chief Executive Officer, and Richard Ghalie, M.D., our Chief Medical Officer, stepped down effective August 1, 2024. Mr. Urso also left the Board at that date. We have entered into consulting agreements with both Mr. Urso and Dr. Ghalie under which they will remain available to assist us in our strategic efforts. Charles V. Baltic III, the Chairperson of the Board, also stepped down from the Board contemporaneously with the announcement on July 22, 2024. Our Board has appointed Justin J. File, our current Chief Financial Officer, to assume the position of Acting Chief Executive Officer and has appointed Frederick W. Driscoll as Chairperson of the Board.

Cooperation Agreement

On October 31, 2023, we announced our entry into a Cooperation Agreement (Cooperation Agreement) with Anson Funds Management LP and Cable Car Capital LLC (Anson and Cable Car, respectively), which, among other non-financial related items provided for a capital return to stockholders in the form of a dividend in the amount of $1.75 per share of common stock, as further discussed below. Additionally, the Cooperation Agreement contemplated a potential second return of capital not to exceed $9.33 million (Potential Second Return of Capital) if authorized by Board should our ongoing ME-344 Phase 1b trial fail to meet certain defined endpoints or our Board determines not to proceed with a second cohort.

As part of the Cooperation Agreement, Anson and Cable Car withdrew their consent solicitation and agreed to abide by customary standstill provisions. Additionally, we reimbursed Anson's and Cable Car’s fees and expenses related to their engagement with us as of the date of the Cooperation Agreement in an amount of $1.1 million, which is recorded within general and administrative expenses in the consolidated statements of operations for the fiscal year ended June 30, 2024.

In April 2024, the Board unanimously determined not to proceed with the Potential Second Return of Capital under the Cooperation Agreement in order to conserve resources and align strategic investment, and thereby extend our operational runway.

Cash Dividend

On November 6, 2023, pursuant to the Cooperation Agreement, the Board declared a special cash dividend of $1.75 per share of common stock to stockholders of record at the close of business on November 17, 2023. The total dividend of $11.7 million was paid on December 6, 2023, and was recorded as a reduction of additional paid-in capital in the consolidated statements of stockholders' equity, as we have an accumulated deficit, rather than retained earnings.

Infinity Merger

In February 2023, we, Infinity Pharmaceuticals, Inc. (Infinity), and Meadow Merger Sub, Inc., our wholly owned subsidiary (Merger Sub) entered into an agreement and plan of merger (Merger Agreement). The Merger Agreement provided that Merger Sub will merge with and into Infinity, with Infinity being the surviving entity as a wholly owned subsidiary of us (transaction referred to as the Merger) and was subject to approvals by our and Infinity’s stockholders, respectively. On July 23, 2023, we convened our Special Meeting of Stockholders at which time our stockholders did not approve the proposed transaction and subsequently, we delivered a letter to Infinity which terminated the Merger Agreement pursuant to Section 7.2(c) of the Merger Agreement, effective July 23, 2023.

KKC Termination Agreement

In November 2022, we and Kyowa Kirin Co., Ltd. (KKC) met with the U.S. Food and Drug Administration (FDA) in a follow-up meeting to the March 2022 end of Phase 2 meeting related to zandelisib. At this meeting, the FDA provided further guidance regarding the design and statistical analysis for the COASTAL trial. Following the November meeting, the companies jointly concluded that a clinical trial consistent with the recent FDA guidance, including modification of the ongoing COASTAL trial, would likely not be feasible to complete within a time period that would support further investment or with sufficient certainty of the regulatory requirements for approval to justify continued global development efforts. As a result, we and KKC jointly decided to discontinue global development of zandelisib for indolent forms of non-Hodgkin lymphoma outside of Japan.

The discontinuation of zandelisib development outside of Japan was a business decision based on the regulatory guidance from the FDA and was not related to the zandelisib clinical data generated to date. Although KKC continued certain ongoing Japanese clinical trials at that time, in May 2023 KKC decided to discontinue development of zandelisib in Japan after meeting with the Pharmaceuticals and Medical Devices Agency (PMDA), concluding that conducting a randomized study consistent with agency guidance to support a marketing application would likely not be feasible to complete within a time period that would support further investment.

Due to KKC’s decision to discontinue development of zandelisib in Japan, as well as the prior joint decision to discontinue zandelisib development outside of Japan, on July 14, 2023, the parties entered into a Termination Agreement to mutually terminate the global License, Development and Commercialization Agreement executed in April 2020.

Liquidity

We have accumulated losses of $388.2 million since inception and expect to incur operating losses and generate negative cash flows from operations for the foreseeable future. As of June 30, 2024, we had $38.3 million in cash, cash equivalents and short-term investments. In connection with our July 2024 announcement regarding the evaluation of our strategic alternatives, we have discontinued the clinical development of voruciclib, while certain nonclinical research and development activities continue. As a result, we will continue to incur research and development expenses in connection with clinical trial closing costs and the completion of our nonclinical projects. We believe that our cash balance, including our short-term investments, will be sufficient to meet our obligations and fund operations for at least the next 12 months from the issuance of these consolidated financial statements.

To date, we have obtained cash and funded our operations primarily through equity financings and license agreements and to continue the development of our drug candidates, we would require one or more capital transactions, whether through the sale of equity securities, debt financing, license agreements or entry into strategic partnerships at some point in the future. There can be no assurance that we will be able to continue to raise additional capital in the future.