Form 8-K Summary: Aptose Biosciences Inc.

Date of Event: November 3, 2025

This Form 8-K serves primarily as a Regulation FD Disclosure regarding the issuance of a press release on the filing date.

• The substance of the material information (financials, events, guidance) is contained within Exhibit 99.1.
• The filing itself does not detail the content of the announcement.

Key investor takeaway: Investors must review Exhibit 99.1 (the referenced press release) to understand the material updates from Aptose Biosciences Inc.

The report was authorized by CEO, William G.