Second Amendment

Exhibit 99.3

Second Amendment

This Amendment (the "Second Amendment") effective as of May 13, 2016 (the "Effective Date"), is entered into by and between CRYSTALGENOMICS, INC., a South Korean corporation having a place of business at 5th F. Bldg.A, Korea Bio Park, 700 Daewangpangyo-ro, Bundang-gu, Seongnam-si, Gyeonggi-do, 463-400 Korea ("CG") and APTOSE BIOSCIENCES, INC., a Canadian corporation having a place of business at 0000 Xxxxxxx Xxxx, Xxxxx 000, Xxxxxxxxxxx, Xxxxxxx, X0X 0X0, Xxxxxx ("Aptose"). CG and Aptose are sometimes referred to herein individually as a "Party" and collectively as the "Parties".

The Parties hereby desire to make an amendment of the OPTION AND LICENSE AGREEMENT (the "Agreement") between CG and Aptose with an Execution Date of March 24, 2016 to revise following terms and conditions per below, pursuant to Sections 3.1 (iv) and 3.6 of the Agreement.

1. Section 3.1 (iv): The parties agree to extend the Option Period to twenty-four (24) months, unless extended pursuant to Section 3.6 (Diligence).

2. Section 3.6: The parties agree to that the period in which Aptose must obtain acceptance for filing and review of an IND for a Product in the Licensed Territory be extended to within twenty-four (24) months after the commencement of the Option Period.

IN WITNESS WHEREOF, the parties hereto have caused this Second Amendment to be executed as of the Effective Date written above by their respective authorized representatives. The parties hereby affirm that this Second Amendment accurately and completely reflects their understanding and agreements.

CRYSTALGENOMICS, INC.			APTOSE BIOSCIENCES, INC.
By:	/s/ Dr. Joong Xxxxx Xxx		By:	/s/ Xxxxxxx Xxxxxxxx
Name:	Dr. Joong Xxxxx Xxx		Name:	Xxxxxxx Xxxxxxxx
Title:	CEO		Title:	SVP, Chief Business Officer
Date:	May 13, 2016		Date:	May 13, 2016