PLUS THERAPEUTICS, INC.

S-11 d942543ds1.htm S-1

As filed with the Securities and Exchange Commission on August 12, 2025.

Registration No. 333-

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

**Form S-1 **

REGISTRATION STATEMENT

Under

The Securities Act of 1933

PLUS THERAPEUTICS, INC.

(Exact name of Registrant as specified in its charter)

2710 Reed Road, Suite 160

Houston, Texas 77002

(737)255-7194

(Address, including zip code, and telephone number, including area code, of Registrant’s principal executive offices)

Andrew Sims

Chief Financial Officer

Plus Therapeutics, Inc.

2710 Reed Road, Suite 160

Houston, Texas 77002

(737)255-7194

(Name, address, including zip code, and telephone number, including area code, of agent for service)

Copies to:

David E. Danovitch

Aaron M. Schleicher

Sullivan & Worcester LLP

1251 Avenue of the Americas

New York, New York 10020

(212)660-3060

Approximate date of commencement of proposed sale to the public: From time to time after this registration statement becomes effective, as determined by the selling stockholder.

If any of the securities being registered on this Form are to be offered on a delayed or continuous basis pursuant to Rule 415 under the Securities Act, check the following box: ☒

If this Form is filed to register additional securities for an offering pursuant to Rule 462(b) under the Securities Act, please check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering. ☐

If this Form is a post-effective amendment filed pursuant to Rule 462(c) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering. ☐

If this Form is a post-effective amendment filed pursuant to Rule 462(d) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering. ☐

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, anon-accelerated filer, a smaller reporting company or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company,” and “emerging growth company” in Rule 12b-2 of the Exchange Act.

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 7(a)(2)(B) of the Securities Act. ☐

The Registrant hereby amends this Registration Statement on such date or dates as may be necessary to delay its effective date until the Registrant shall file a further amendment which specifically states that this Registration Statement shall thereafter become effective in accordance with the provisions of Section 8(a) of the Securities Act of 1933 or until the Registration Statement shall become effective on such date as the Commission, acting pursuant to said Section 8(a), may determine.

The information in this prospectus is not complete and may be changed. We may not sell these securities until the registration statement filed with Securities and Exchange Commission is effective. This prospectus is not an offer to sell these securities and is not soliciting an offer to buy these securities in any state where the offer or sale is not permitted.

PRELIMINARY PROSPECTUS

(Subject to Completion, Dated August 12, 2025)

33,000,000 Shares of Common Stock

This prospectus relates to the offer and sale of up to 33,000,000 shares of our common stock, par value $0.001 per share, by Lincoln Park Capital Fund, LLC, which we refer to in this prospectus as Lincoln Park or the selling stockholder.

The shares of common stock to which this prospectus relates may be issued by us to Lincoln Park, subject to certain limitations described in this prospectus, pursuant to a purchase agreement, dated as of June 17, 2025 we entered into with Lincoln Park (the “Purchase Agreement”). As of the date of this prospectus, we have received gross proceeds of approximately $2.8 million from sales of shares of common stock pursuant to the Purchase Agreement, the resale of which shares were registered pursuant to a separate registration statement on Form S-1 initially filed on June 18, 2025 (as amended, the “Prior Registration Statement”). We are not selling any securities under this prospectus and will not receive any of the proceeds from the sale of our common stock by the selling stockholder. However, we may receive up to $25 million aggregate gross proceeds (the “Initial Available Amount”) from sales of common stock to Lincoln Park under the Purchase Agreement and, upon our receipt of gross proceeds equal to the full Initial Available Amount from such sales, the total aggregate dollar amount that will be available to us under the Purchase Agreement will automatically increase by an additional $25 million aggregate gross proceeds (such additional amount, the “Additional Available Amount”), and thereafter we may receive up to such Additional Available Amount (or up to a total of $50 million aggregate gross proceeds (the “Total Available Amount”)) from sales of common stock to Lincoln Park under the Purchase Agreement. Pursuant to the Purchase Agreement, as consideration for its irrevocable commitment to purchase up to the Initial Available Amount of shares of our common stock at our direction under the Purchase Agreement, we agreed to pay Lincoln Park a commitment fee of $500,000 (the “Initial Commitment Fee”), on or prior to August 8, 2025 (the “Initial Commitment Fee Trigger Date”) in cash or, if we comply with certain requirements set forth in the Purchase Agreement, by issuing shares of our common stock with a per share value calculated in accordance with the Purchase Agreement (such shares, the “Initial Commitment Shares”), or any combination thereof. We intend to issue 1,612,903 shares of our common stock with a per share value of $0.31 as the Initial Commitment Shares.

We also agreed that, upon our receipt of aggregate gross proceeds equal to the Initial Available Amount (the “Additional Commitment Fee Trigger Date”), as consideration for its irrevocable commitment to purchase up to the Additional Available Amount of shares of our common stock at our direction under the Purchase Agreement, we will then pay Lincoln Park an additional commitment fee of $500,000 (the “Additional Commitment Fee”) in cash or, if we comply with certain requirements set forth in the Purchase Agreement, by issuing shares of our common stock with a per share value calculated in accordance with the Purchase Agreement (such shares, the “Additional Commitment Shares”), or any combination thereof. See “The Lincoln Park Transaction” for a description of the Purchase Agreement and “Selling Stockholder” for additional information regarding Lincoln Park.

The selling stockholder may sell or otherwise dispose of the shares of common stock described in this prospectus in a number of different ways and at varying prices. See “Plan of Distribution” for more information about how the selling stockholder may sell or otherwise dispose of the common stock being registered pursuant to this prospectus. The selling stockholder is an “underwriter” within the meaning of Section 2(a)(11) of the Securities Act of 1933, as amended (the “Securities Act”).

The selling stockholder will pay all brokerage fees and commissions and similar expenses in connection with any resale or disposition of the shares of common stock described in this prospectus by the selling stockholder. We will pay the expenses incurred in registering under the Securities Act the offer and sale of the shares of common stock to which this prospectus relates by the selling stockholder, including legal and accounting fees. See “Plan of Distribution”.

Our common stock is currently listed on the Nasdaq Capital Market (“Nasdaq”) under the symbol “PSTV”. On August 8, 2025, the closing price of our common stock, as reported on Nasdaq, was $0.80 per share.

Investing in our securities involves a high degree of risk. These risks are described in the “Risk Factors” section on page 4 of this prospectus. You should also consider the risk factors described or referred to in any documents incorporated by reference in this prospectus, and in any applicable prospectus supplement, before investing in these securities.

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or determined if this prospectus is truthful or complete. Any representation to the contrary is a criminal offense.

The date of this prospectus is , 2025