Callisto Pharmaceuticals, Inc. Receives Notice of Delisting From Amex - Subject to Appeal -

  
    
  
  
    
      Callisto Pharmaceuticals, Inc. (AMEX: KAL), announced today that on 
      April 7, 2008, it received notice from the American Stock Exchange 
      indicating that AMEX intends to strike the Company’s 
      common stock from listing on AMEX by filing a delisting application with 
      the Securities and Exchange Commission. In its letter, AMEX stated that 
      it has determined that the Company has failed to comply with continued 
      listing standards set forth in Sections 1003(a)(i), 1003(a)(ii) and 
      1003(a)(iii) of the AMEX Company Guide, respectively, which state, in 
      relevant part, that AMEX will normally consider suspending dealings in, 
      or removing from the list, securities of a company which (a) has 
      stockholders' equity of less than $2,000,000 if such company has 
      sustained losses from continuing operations and/or net losses in two of 
      its three most recent fiscal years; (b) has stockholders' equity of less 
      than $4,000,000 if such company has sustained losses from continuing 
      operations and/or net losses in three of its four most recent fiscal 
      years; or (c) has stockholders' equity of less than $6,000,000 if such 
      company has sustained losses from continuing operations and/or net 
      losses in its five most recent fiscal years, respectively.
    
    
      The AMEX rules provide for an appeal of the above decision which the 
      Company has made by requesting a hearing in accordance with appropriate 
      procedures as outlined by the AMEX Company Guide. The Company’s 
      common stock will continue to trade on the AMEX during the appeal 
      process. If unsuccessful on appeal, the Company intends to continue to 
      trade on the Over-the-Counter Bulletin Board.
    
    
      Callisto also announced today that the audit report of BDO Seidman, LLP, 
      contained in its December 31, 2007 financial statements included in 
      Callisto's Form 10-K filed on March 28, 2008, contained a going-concern 
      qualification. American Stock Exchange rules require Amex-listed 
      companies to publicly announce whenever a Form 10-K includes an audit 
      report containing a going-concern qualification.
    
    
      About Callisto Pharmaceuticals, Inc.
    
    
      Callisto is a biopharmaceutical company focused on the development of 
      new drugs to treat various forms of gastrointestinal diseases and 
      cancer. Callisto's drug candidates include SP-304, a proprietary drug 
      for gastrointestinal disorders that is currently being developed by its 
      wholly-owned subsidiary, Synergy Pharmaceuticals, as well as two 
      anti-cancer agents. Synergy's proprietary drug SP-304 (Guanilib) is 
      planned to begin clinical development in 2Q2008 for gastro-intestinal 
      disorders. SP-304 is a synthetic analog of the human gastrointestinal 
      hormone uroguanylin, and acts by activating the guanylate cyclase C 
      (GC-C) receptor on epithelial cells of the colon. The Company's lead 
      drug in the clinic, Atiprimod, is presently in a Phase II clinical trial 
      in advanced carcinoid cancer, a neuroendocrine tumor, and in a Phase II 
      extension trial in advanced carcinoid cancer patients. Callisto's second 
      cancer drug in the clinic, L-Annamycin, is currently in a Phase I/II 
      clinical trial in adult relapsed or refractory acute lymphocytic 
      leukemia, and in a Phase I clinical trial in children and young adults 
      with refractory or relapsed acute lymphocytic leukemia or acute 
      myelogenous leukemia. Callisto has exclusive worldwide licenses from 
      Genzyme Inc. and M.D. Anderson Cancer Center to develop, manufacture, 
      use and sell Atiprimod and L-Annamycin, respectively. Callisto is also 
      listed on the Frankfurt Stock Exchange under the ticker symbol CA4. More 
      information is available at http://www.callistopharma.com.
    
    
      Web site: http://www.callistopharma.com