# EDGAR Filing Document

**Accession Number:** 0000882361
**File Stem:** 0001193125-26-119982
**Filing Date:** 2026-3
**Character Count:** 3551
**Document Hash:** df6a63e5750f89d0be553af9647e77bb
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0001193125-26-119982.hdr.sgml**: 20260323

**ACCESSION NUMBER**: 0001193125-26-119982

**CONFORMED SUBMISSION TYPE**: RW

**PUBLIC DOCUMENT COUNT**: 1

**FILED AS OF DATE**: 20260323

**DATE AS OF CHANGE**: 20260323

**FILER**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** Aptose Biosciences Inc.
- **CENTRAL INDEX KEY:** 0000882361
- **STANDARD INDUSTRIAL CLASSIFICATION:** BIOLOGICAL PRODUCTS (NO DIAGNOSTIC SUBSTANCES) [2836]
- **ORGANIZATION NAME:** 03 Life Sciences
- **EIN:** 000000000
- **STATE OF INCORPORATION:** A6
- **FISCAL YEAR END:** 1231

**FILING VALUES:**
- **FORM TYPE:** RW

**SEC ACT:**
- **SEC FILE NUMBER:** 333-284927
- **FILM NUMBER:** 26783236

**BUSINESS ADDRESS:**
- **ADDRESS IS A NON US LOCATION:** YES
- **STREET 1:** 66 WELLINGTON STREET WEST, SUITE 5300
- **STREET 2:** TD BANK TOWER BOX 48
- **CITY:** TORONTO
- **PROVINCE COUNTRY:** A6
- **BUSINESS PHONE:** 310-849-8060

**MAIL ADDRESS:**
- **ADDRESS IS A NON US LOCATION:** YES
- **STREET 1:** 66 WELLINGTON STREET WEST, SUITE 5300
- **STREET 2:** TD BANK TOWER BOX 48
- **CITY:** TORONTO
- **PROVINCE COUNTRY:** A6

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** Aptose Biosciences Inc., (formerly LORUS THERAPEUTICS INC.)
- **DATE OF NAME CHANGE:** 20140905

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** LORUS THERAPEUTICS INC
- **DATE OF NAME CHANGE:** 19990308

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** IMUTEC PHARMA INC
- **DATE OF NAME CHANGE:** 19970113

**Aptose Biosciences Inc.** 

**66 Wellington Street West, Suite 5300** 

**TD Bank Tower, Box 48** 

**Toronto, Ontario M5K 1E6 Canada** 

March 23, 2026

**<u>VIA EDGAR</u>**

Division of Corporation Finance

Securities and Exchange Commission

100 F Street, N.E.

Washington, D.C. 20549

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| | |
|:---|:---|
| **Re:** | **Aptose Biosciences Inc.**  |

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**Withdrawal of Registration Statement on Form S-1** 

**File No. 333-284927** 

Ladies and Gentlemen:

Pursuant to Rule 477 of the Securities Act of 1933, as amended ("Securities Act"), Aptose Biosciences Inc. (the "Company"), hereby requests the immediate withdrawal of its Registration Statement on Form S-1 (File No. 333-284927), initially filed with the U.S. Securities and Exchange Commission ("SEC") on February 12, 2025, together with all exhibits thereto ("Registration Statement"), with such application for withdrawal to be approved effective as of the date first set forth above or at the earliest practical date thereafter. The Company is seeking withdrawal of the Registration Statement, as it does not intend to pursue the contemplated offering of the securities covered by the Registration Statement at this time. The Registration Statement has not been declared effective, and the Company confirms that no securities of the Company were sold pursuant to the Registration Statement.

The Company requests that, in accordance with Rule 457(p) under the Securities Act, all fees paid to the SEC in connection with the filing of the Registration Statement be credited for future use.

If you have any further questions regarding this request for withdrawal, or if you require any additional information, please contact Daniel M. Miller of Dorsey & Whitney LLP at (604) 630-5199.

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| | |
|:---|:---|
| Very truly yours, | Very truly yours, |
| Aptose Biosciences Inc. | Aptose Biosciences Inc. |
| By: | /s/ William G. Rice, Ph.D. |
|  | William G. Rice, Ph.D. |
|  | Chairman, President, and Chief Executive<br>Officer |

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cc: Daniel M. Miller, Esq., Dorsey & Whitney LLP