0.50% Uses in Underwritten Offering Clause

Underwritten Offering from Registration Rights Agreement

Cell Therapeutics, Inc., a corporation organized under the laws of the State of Washington (the Company), proposes to issue and sell to the initial purchaser (the Initial Purchaser) named in the Purchase Agreement, dated October 31, 2005, by and between the Initial Purchaser and the Company (the Purchase Agreement), its 6.75% Convertible Senior Notes due 2010 (the Securities) and warrants to purchase 350,000 shares of its Common Stock (the Warrant), upon the terms and subject to the conditions set forth in such Purchase Agreement. As an inducement to the Initial Purchaser to enter into the Purchase Agreement and in satisfaction of a condition to the obligations of the Initial Purchaser thereunder, the Company agrees with the Initial Purchaser for the benefit of Holders (as defined herein) from time to time of the Registrable Securities (as defined herein) as follows:

Underwritten Offering. Any holder of Registrable Securities who desires to do so may sell Registrable Securities (in whole or in part) in an underwritten offering; provided, however, the Company shall not be required to facilitate an underwritten offering pursuant to the Shelf Registration Statement by any holders unless the offering relates to at least $20,000,000 principal amount of Securities or the equivalent number of shares of Common Stock in which such Securities are convertible. In any such underwritten offering, the investment banker or investment bankers and manager or managers that will administer the offering will be selected by, and the underwriting arrangements with respect thereto (including the size of the offering) will be approved by, the holders of a majority of the Registrable Securities to be included in such offering; provided, however, that such investment bankers and managers and underwriting arrangements must be reasonably satisfactory to the Company. No holder may participate in any underwritten offering contemplated hereby unless (a) such holder agrees to sell such holders Registrable Securities to be included in the underwritten offering in accordance with any approved underwriting arrangements, (b) such holder completes and executes all reasonable questionnaires, powers of attorney, indemnities, underwriting agreements, lock-up letters and other documents required under the terms of such approved underwriting arrangements and (c) if such holder is not then an Electing Holder, such holder returns a completed and signed Notice and Questionnaire to the Company in accordance with Section 3(a)(ii) hereof within a reasonable amount of time before such underwritten offering. The holders participating in any underwritten offering shall be responsible for any underwriting discounts and commissions and fees and, subject to Section 4 hereof, expenses of their own counsel. The Company shall pay all expenses customarily borne by issuers, including but not limited to filing fees, the fees and disbursements of its counsel and independent public accountants and any printing expenses incurred in connection with such underwritten offering. Notwithstanding the foregoing or the provisions of Section 3(n) hereof, upon receipt of a request from the Managing Underwriter or a representative of holders of a majority of the Registrable Securities to be included in an underwritten offering to prepare and file an amendment or supplement to the Shelf Registration Statement and + Prospectus in connection with an underwritten offering, the Company may delay the filing of any such amendment or supplement for up to sixty (60) days if the Company is in possession of material non-public information the disclosure of which would have a material adverse effect on the business, operations, prospects, condition (financial or otherwise) of the Company and its subsidiaries, taken as a whole.