Attached files

file filename
10-K - 10-K - CALLISTO PHARMACEUTICALS INCa2197674z10-k.htm
EX-21 - EXHIBIT 21 - CALLISTO PHARMACEUTICALS INCa2197674zex-21.htm
EX-32.2 - EXHIBIT 32.2 - CALLISTO PHARMACEUTICALS INCa2197674zex-32_2.htm
EX-31.2 - EXHIBIT 31.2 - CALLISTO PHARMACEUTICALS INCa2197674zex-31_2.htm
EX-32.1 - EXHIBIT 32.1 - CALLISTO PHARMACEUTICALS INCa2197674zex-32_1.htm
EX-31.1 - EXHIBIT 31.1 - CALLISTO PHARMACEUTICALS INCa2197674zex-31_1.htm

QuickLinks -- Click here to rapidly navigate through this document


Exhibit 23

Consent of Independent Registered Public Accounting Firm

Callisto Pharmaceuticals, Inc.
New York, New York

        We hereby consent to the incorporation by reference in the Registration Statements on Form S-8 (No. 333-119648 and 333-130716) of Callisto Pharmaceuticals, Inc. and Subsidiaries (a development stage company) (the "Company") of our report dated March 31, 2010, relating to the consolidated financial statements which appear in this Form 10-K. Our report on the consolidated financial statements contains an explanatory paragraph regarding the Company's ability to continue as a going concern.

/s/ BDO Seidman, LLP

New York, New York
March 31, 2010




QuickLinks