PLUS THERAPEUTICS, INC.

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 14A

Proxy Statement Pursuant to Section 14(a) of the

Securities Exchange Act of 1934

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Filed by a Party other than the Registrant ☐

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PLUS THERAPEUTICS, INC.

(Name of Registrant as Specified in Its Charter)

(Name of Person(s) Filing Proxy Statement, if other than the Registrant)

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6420 Levit Green Boulevard, Suite 310

Houston, Texas 77021

March 31, 2026

To Our Stockholders:

This year holds the potential to be the most transformational in Company history. Commercializing our first products, bringing our lead drug to registrational trials and relaunching with a new and unique mission to improve survival in central nervous cancer is all in our plan for the year. In the past few years, through multiple transactions, we have built a foundation for improved patient outcomes and building stockholder value.

In our first full year operating three integrated businesses, specifically: therapeutics, diagnostics, and advanced data analytics, we have already made major strides. I would like to dive deeper into each focus area and provide guidance for the year.

Our lead investigational radiotherapeutic drug, REYOBIQTM, is being evaluated for three central nervous system (CNS) cancers—leptomeningeal metastases (LM), pediatric brain cancer (PBC), and recurrent glioblastoma (rGBM). There is a growing epidemic of brain cancer led largely by metastatic diseases such as LM, which is tumor in the fluid space around the brain. In 2026, building on the completed ReSPECT-LM safety trial for patients with LM and an end of phase meeting with the FDA last year, we are enrolling in an optimal dose/interval trial leading into a Phase 2 expansion trial. We anticipate reporting data in the third quarter of 2026. In our ongoing glioblastoma Phase 2 trial, ReSPECT-GBM, we intend to complete enrollment, present data and schedule an end of phase meeting with the FDA to seek alignment on pivotal trial design by Q4 2026. Finally, we expect to begin enrollment in the ReSPECT-PBC Phase 1 trial in 2026. To be pivotal trial ready in early 2027, we are shifting our principal REYOBIQ radiotherapeutic manufacturing to SpectronRx, which will provide us with commercial scale.

To meet the clinical demands of the growing epidemic in brain cancer, better diagnostics are needed to both identify affected patients and help caregivers manage the disease. This led to our recent launch of our CNSide® CSF diagnostic platform. In 2026, we intend to scale manufacturing, testing capabilities and sales related functions. Key objectives in 2026 are to expand the payor base to at least 150 million covered lives, obtain Medicare coverage, substantially increase the customer base, bring new testing capabilities to market, and drive testing utilization. Based on present forecast, our CNSide business unit may breakeven by 2027.

Finally, we intend to implement advanced data analytics across the Company. Beyond the routine and generalized use of artificial intelligence, in 2026, we intend to implement a variety of business-specific uses in both our diagnostic and therapeutic operations. In aggregate, these initiatives should improve efficiency, reduce costs, limit the need to expand our workforce, and drive pipeline innovation. We plan to execute this plan through both internal processes and through strategic partnerships. We will provide updates as key milestones are reached.

Behind the scenes, we have taken steps to strengthen the Company’s capitalization by leveraging our growing CNSide business and advancing clinical pipeline, with focus on maximizing value for our stockholders. On behalf of our employees, management and directors, I would like to express our deep appreciation to our stockholders and partners for their help and support in 2025 and beyond.

Sincerely,

Marc H. Hedrick, M.D.

President & Chief Executive Officer

NOTICE OF 2026 ANNUAL MEETING OF STOCKHOLDERS

TO BE HELD ON MAY 14, 2026

Dear Plus Therapeutics, Inc. Stockholder:

You are cordially invited to attend the 2026 Annual Meeting of the Stockholders of Plus Therapeutics, Inc. (the “Annual Meeting”). The Annual Meeting will be held on May 14, 2026, commencing at 9:00 a.m. (Eastern Time), and will be a completely virtual meeting of stockholders.

The items of business for the meeting are to:

(i)

elect six (6) members of our board of directors for a one-(1) year term, to hold office until our Annual Meeting of Stockholders in 2027 and until their successors are duly elected and qualified, or until their earlier death, resignation or removal;

(ii)

ratify the appointment of CBIZ CPAs, P.C. as our independent registered public accounting firm for the 2026 fiscal year ending December 31, 2026;

(iii)

provide a non-binding advisory vote on the compensation of our named executive officers;

(iv)

approve the sixth amendment and restatement of the Company’s 2020 Stock Incentive Plan, the full text of which resolution is set out in the accompanying proxy statement under the heading “Proposal 4 - Proposal to Approve the Sixth Amendment and Restatement of the 2020 Stock Incentive Plan; and

(v)

transact such any other business as may be properly brought before the Annual Meeting.

The board of directors (“Board”) recommends that stockholders (a) elect each board member nominee; and (b) vote to approve items (ii), (iii) and (iv).

In light of our successful virtual annual meetings of stockholders in the past five years, the Annual Meeting will be held only via live webcast again this year. We believe that the virtual meeting format also expands stockholder access, participation and improves communications, and we encourage you to attend online and participate.

You will be able to attend and participate in the Annual Meeting online, vote your shares electronically, and submit your questions prior to and during the meeting by visiting: www.virtualshareholdermeeting.com/PSTV2026. To vote at the meeting, you must have your control number that is shown on your proxy card. There will not be a physical meeting location and you will not be able to attend the annual meeting in person.

Only stockholders of record at the close of business on March 18, 2026, are entitled to notice of and to vote at the Annual Meeting. For ten (10) days prior to the Annual Meeting, a complete list of stockholders entitled to vote at the Annual Meeting will be available at the Corporate Secretary’s office at 6420 Levit Green Boulevard, Suite 310, Houston, Texas 77021. On or around April 2, 2026, we began mailing our stockholders a Notice of Internet Availability, as permitted under applicable Securities and Exchange Commission (“SEC”) rules. The Notice of Internet Availability indicates how to access our proxy materials on the Internet. By furnishing the Notice of Internet Availability, we are lowering our costs and reducing the environmental impact of our Annual Meeting.

You are cordially invited to attend the Annual Meeting live via the Internet. It is important that your shares are represented at the Annual Meeting. Even if you plan to attend the Annual Meeting live via the Internet, we hope that you will promptly vote by dating, signing and returning the enclosed proxy card or vote via the Internet or by telephone. This will not limit your ability to attend or vote during the Annual Meeting.

Plus Therapeutics, Inc.

By Order of the Board,

MARC H. HEDRICK

President & Chief Executive Officer

Houston, Texas, USA

March 31, 2026