Washington, D.C. 20549

FORM 12b-25




(Check one):

x Form 10-K


o Form 20-F


o Form 11-K


o Form 10-Q and Form 10-QSB


o Form N-SAR




















For Period Ended:


December 31, 2006










o Transition Report on Form 10-K








o Transition Report on Form 20-F








o Transition Report on Form 11-K








o Transition Report on Form 10-Q








o Transition Report on Form N-SAR








For the Transition Period Ended:




Read Instructions (on back page) Before Preparing Form. Please Print or Type.

Nothing in this form shall be construed to imply that the Commission has verified any information contained herein.


If the notification relates to a portion of the filing checked above, identify the Item(s) to which the notification relates:





Callisto Pharmaceuticals, Inc.

Full Name of Registrant



Former Name if Applicable


420 Lexington Avenue, Suite 1609

Address of Principal Executive Office (Street and Number)


New York, New York 10170

City, State and Zip Code





RULE 12b-25 (b) and (c)

If the subject report could not be filed without unreasonable effort or expense and the registrant  seeks  relief  pursuant  to  Rule 12b-25(b), the following should be completed. (Check box if appropriate.)




The reasons described in reasonable detail in Part III of this form could not be eliminated without unreasonable effort or expense.










The subject annual report, semi-annual report, transition report on Form 10-K, 20-F, 11-K or Form N-SAR, or portion thereof will be filed on or before the fifteenth calendar day following the prescribed due date; or the subject quarterly report or transition report on Form 10-Q or portion thereof will be filed on or before the fifth calendar day following the prescribed due date; and










The accountant’s statement or other exhibit required by Rule 12b-25(c)has been attached if applicable




State below in reasonable detail the reasons why Form 10-K, 11-K, 20-F, 10-Q, N-SAR or the transition report portion thereof could not be filed within the prescribed time period.

The Company’s Annual Report on Form 10-K for the year ended December 31, 2006 cannot be filed within the prescribed time period because the Company requires additional time for compilation and review to insure adequate disclosure of certain information required to be included in the Form 10-K.  The Company’s Annual Report on Form 10-K will be filed on or before the 15th calendar day following the prescribed due date.



(1)                                  Name and telephone number of person to contact in regard to this notification:

Bernard F. Denoyer, Vice President, Finance, 212-297-0010



(2)                                Have all other periodic reports required under Section 13 or 15(d) of the Securities Exchange Act of 1934 or Section 30 of the Investment Company Act of 1940 during the preceding 12 months or for such shorter period that the registrant was required to file such report(s) been filed?  If the answer is no, identify report(s)

x Yes

o No


 (3)                               Is it anticipated that any significant change in results of operations from the corresponding period for the last fiscal year will be reflected by the earnings  statements  to  be  included  in  the subject report or portion thereof?


o Yes

x No



If so, attach an explanation of the anticipated change, both narratively and quantitatively, and, if appropriate, state the reason why a reasonable estimate of the results cannot be made.

Callisto Pharmaceuticals, Inc.


(Name of Registrant as specified in Charter)


has caused this notification to be signed on its behalf by the undersigned thereunto duly authorized.


April 2, 2007



 /s/ Bernard F. Denoyer



Bernard F. Denoyer


Vice President, Finance