Exhibit 10.4

CELL THERAPEUTICS, INC.

501 Elliott Avenue West, Suite 400

Seattle, Washington 98119

September 20, 2011

Dr. James A. Bianco

501 Elliott Avenue West, Ste 400

Seattle, WA 98119

Dear Jim:

I write concerning the outstanding award of restricted stock granted to you by
Cell Therapeutics, Inc. (the “Company”) on March 21, 2011 (the “Award”). The
purpose of this letter is to amend the tax withholding provision of the
agreement that evidences the Award (the “Award Agreement”) to provide you with
the opportunity to elect to have the Company satisfy its tax withholding
obligations incurred in connection with the Award by reacquiring a portion of
the shares subject to the Award (as opposed to the Company satisfying its
withholding obligations by automatically reacquiring such shares).

Accordingly, effective immediately, Section 9 of the Award Agreement is hereby
amended and restated to read in its entirety as follows:

“9. Tax Withholding. The Company (or any of its Subsidiaries last employing the
Participant) shall be entitled to require a cash payment by or on behalf of the
Participant and/or to deduct from other compensation payable to the Participant
any sums required by federal, state or local tax law to be withheld with respect
to the vesting of any Restricted Shares. Alternatively, the Company may (but is
not required to) permit the Participant to elect, in such manner and at such
time or times prior to any applicable tax date as may be permitted or required
under Section 11 of the Plan and rules established by the Committee, to have the
Company withhold and reacquire Restricted Shares at their Fair Market Value at
the time of vesting to satisfy any withholding obligations of the Company or its
Subsidiaries with respect to such vesting. Any election to have shares so held
back and reacquired shall be subject to such rules and procedures as the
Committee may impose, and shall not be available if the Participant makes or has
made an election pursuant to Section 83(b) of the Code with respect to such
Award.”

Except as expressly set forth above, this letter agreement does not modify any
other terms of your Award. In other words, the existing vesting, termination of
employment and other provisions of your Award continue in effect.

 

Sincerely, Cell Therapeutics, Inc.

/s/ Louis A. Bianco

Louis A. Bianco Executive Vice President, Finance and Administration