Company: PSTV
Filing Date: 2025-04-11
Form Type: POS AM
Source: 0001193125-25-079109
Chunk: 1

Company: PLUS THERAPEUTICS, INC.
Filing Date: 2025-04-11
Form: POS AM
Chunk 1
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 a post-effective amendment thereto that shall become effective upon filing with the Commission pursuant to Rule 462(e) under the Securities Act, check the following box. ☐ If this Form is a post-effective amendment to a registration statement filed pursuant to General Instruction I.D. filed to register additional securities or additional classes of securities pursuant to Rule 413(b) under the Securities Act, check the following box. ☐ Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-acceleratedfiler, 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-2of the Exchange Act.

| Large accelerated filer |     | ☐ |     | Accelerated filer         |     | ☐ |
| Non-accelerated filer   |     | ☒ |     | Smaller reporting company |     | ☒ |
|                         |     |   |     | Emerging growth company   |     | ☐ |

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 that specifically states that this registration statement shall thereafter become effective in accordance with Section 8(a) of the Securities Act of 1933 or until this registration statement shall become effective on such date as the Securities and Exchange Commission, acting pursuant to said Section 8(a), may determine.

EXPLANATORY NOTE

On June 7, 2024, Plus Therapeutics, Inc. (the “Registrant”) filed a registration statement with the Securities and Exchange Commission
(“SEC”) on Form S-1 (File No. 333-280061), which was declared effective by the SEC on June 24, 2024. The registration statement initially registered the resale from time to time by selling stockholders named therein of up to a total of
10,774,596 shares of our common stock, par value $0.001 per share (“common stock”), consisting of up to: (i) 1,439,988 shares of common stock