Xilio (XLO) cuts Leerink-led stock offering capacity to $9.5M

Rhea-AI Filing Summary

Xilio Therapeutics is updating its stock sale program to offer up to an aggregate of $9,500,000 of common stock through its existing sales agreement with Leerink Partners LLC. This reduces the previous capacity of up to $50,000,000 under the earlier prospectus. The shares may be sold from time to time under the Form S-3 shelf, and as of February 10, 2026, the last reported sale price of the common stock on The Nasdaq Capital Market under the symbol “XLO” was $0.5415 per share.

PROSPECTUS SUPPLEMENT (To Prospectus dated May 8, 2025) Filed Pursuant to Rule 424(b)(5) Registration No. 333-285703

Up to $9,500,000

Common Stock

This prospectus supplement amends and supplements certain information in the prospectus, dated May 8, 2025, filed with the Securities and Exchange Commission as a part of our registration statement on Form S-3 (File No. 333-285703), which we refer to as the Prior Prospectus, relating to the offer and sale of shares of our common stock, par value $0.0001 per share, having an aggregate offering price of up to $50,000,000 pursuant to the Sales Agreement, dated March 11, 2025, or the sales agreement, that we previously entered into with Leerink Partners LLC. As of the date of this prospectus supplement, we have not sold any shares of our common stock in accordance with the sales agreement under the Prior Prospectus. This prospectus supplement should be read in conjunction with the Prior Prospectus, and is qualified by reference thereto, except to the extent that the information herein amends or supersedes the information contained in the Prior Prospectus. This prospectus supplement is not complete without, and may only be delivered or utilized in connection with, the Prior Prospectus and any future amendments or supplements thereto.

We are filing this prospectus supplement to amend the Prior Prospectus to reduce the amount of common stock we may offer and sell under the sales agreement such that we are offering up to an aggregate of $9,500,000 of our common stock for sale under the sales agreement from and after the date hereof.

Our common stock is listed on The Nasdaq Capital Market under the trading symbol “XLO.” On February 10, 2026, the last sale price of our common stock as reported on The Nasdaq Capital Market was $0.5415 per share.

Investing in our common stock involves certain risks. See “Risk Factors” beginning on page SA-7 of the Prior Prospectus and in the documents incorporated by reference in the Prior Prospectus for a discussion of the factors you should carefully consider before deciding to invest in our common stock.

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or passed upon the adequacy or accuracy of the Prior Prospectus or this prospectus supplement. Any representation to the contrary is a criminal offense.

Leerink Partners

February 11, 2026

FAQ

What is XLO offering under this new prospectus supplement?

Xilio Therapeutics is offering up to $9,500,000 of common stock under its existing sales agreement with Leerink Partners LLC. This stock may be sold over time using a previously filed Form S-3 shelf registration and related prospectus.

How does this prospectus supplement change XLO's prior stock offering plans?

The supplement reduces the amount available for sale under the sales agreement. The prior prospectus covered up to $50,000,000 of common stock; the amended arrangement now permits up to $9,500,000 to be offered from and after the date of this supplement.

What is the role of Leerink Partners in XLO's stock offering?

Leerink Partners LLC acts as sales agent under the sales agreement, handling the offer and sale of Xilio’s common stock covered by the shelf registration statement and prospectus, including this prospectus supplement that revises the maximum aggregate offering amount.

On which exchange does XLO trade and at what recent price?

Xilio’s common stock trades on The Nasdaq Capital Market under the symbol “XLO”. On February 10, 2026, the last reported sale price of the common stock on that market was $0.5415 per share.

Does this prospectus supplement stand alone without the prior prospectus for XLO?

No, the prospectus supplement must be read together with the prior prospectus. It amends and supplements information in the earlier document and is not complete on its own without the prior prospectus and any future amendments or supplements.

What risks are associated with investing in XLO common stock under this offering?

Investing in Xilio’s common stock involves certain risks. Investors are directed to the “Risk Factors” section beginning on page SA-7 of the prior prospectus and related incorporated documents for a discussion of key considerations before deciding to purchase shares.