Company: PSTV
Filing Date: 2025-08-12
Form Type: S-1
Source: 0001193125-25-178940
Chunk: 8

Company: PLUS THERAPEUTICS, INC.
Filing Date: 2025-08-12
Form: S-1
Chunk 8
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 938 shares of Series C Preferred Stock, respectively;                                                  |

| • |     | 4,341,400 shares of common stock issuable upon exercise of pre-funded or 
 zero strike price warrants to purchase common stock; and                 |

| • |     | 3,141,993 shares of common stock issuable upon the exercise of warrants to purchase common stock, with a 
 weighted-average exercise price of $1.79 per share.                                                      |

3

RISK FACTORS

Investing in our securities involves a high degree of risk. Before making an investment decision with respect to our securities, we urge you to carefully consider the risks described below and in the “Risk Factors” sections of our most recent Annual Report on Form 10-Kand Quarterly Reports on Form 10-Q,as well as our Current Reports on Form 8-K,filed with the SEC and incorporated by reference in this prospectus, and the other information contained in this prospectus. The risks and uncertainties incorporated by reference into this prospectus or described below are not the only ones we face. Additional risks and uncertainties not presently known or which we consider immaterial as of the date hereof may also materially harm our business and could result in a complete loss of your investment. If any of the matters discussed in the following risk factors were to occur, our business, financial condition, results of operations, cash flows, or prospects could be materially and adversely affected, the market price of our common stock could decline, and you could lose all or part of your investment in our securities.

Risks Related to the Offering

The sale or issuance of our common stock to Lincoln Park may cause dilution to our other stockholders and the sale of the shares of common stock acquired by Lincoln Park, or the perception that such sales may occur, could cause the price of our common stock to fall.

Lincoln Park has committed to purchase up to $50 million aggregate gross proceeds from sales of common stock (initially
$25 million (the “Initial Available Amount”) and if the full Initial Available Amount is purchased, then immediately and automatically up to an additional $25 million aggregate gross proceeds) of our common stock under the
Purchase Agreement, of which they have previously purchased approximately $2.8 million through August 8, 2025. The purchase price for the shares that we may sell to Lincoln Park under the Purchase Agreement remains subject to the pricing formula in
the Purchase Agreement and will fluctuate based on the price of our common stock. Depending on market liquidity at