EX-99.1

                                                                    Exhibit 99.1


                            Explanation of Responses


(1)  These shares of Common Stock, par value $0.001 per share, of the issuer
     ("Common Stock") are held directly by Oracle Investment Management, Inc.
     (the "Investment Manager"), Oracle Partners, L.P. ("Oracle Partners") and
     Oracle Institutional Partners, L.P. ("Oracle Institutional"). Mr. Larry N.
     Feinberg ("Mr. Feinberg") is the sole shareholder and president of the
     Investment Manager and is the senior managing member of Oracle Associates,
     LLC, the general partner of Oracle Partners and Oracle Institutional (the
     "General Partner"). In accordance with instruction 4(b)(iv), the entire
     number of shares of Common Stock that may be deemed to be beneficially
     owned by Mr. Feinberg by virtue of his position with the Investment Manager
     and the General Partner is reported herein. Mr. Feinberg disclaims any
     beneficial ownership of the securities held by Oracle Partners and Oracle
     Institutional for purposes of Section 16 of the Securities Exchange Act of
     1934, except to the extent of Mr. Feinberg's pecuniary interest.

EX-99.2

                                                                    Exhibit 99.2


                         FORM 4 JOINT FILER INFORMATION

          (Attachment to Form 4 in accordance with instruction 4(b)(v))


Check this box if no longer subject to Section 16: [ X ]

Name and Address:                            Oracle Investment Management, Inc.
                                             200 Greenwich Avenue, 3rd Floor
                                             Greenwich, CT 06830

Issuer and Ticker Symbol:                    GTx, Inc. [GTXI]

Date of Earliest Transaction:                8/16/04

Relationship to Issuer:                      10% Owner

Designated Filer:                            Larry N. Feinberg

TABLE I INFORMATION
Title of Security:                           Common Stock
Transaction Date:                            8/16/04
Transaction Code:                            S
Securities Disposed:                         345,000
Acquired or Disposed:                        D
Amount Beneficially Owned after Transaction: 2,292,360
Ownership Form:                              D



Signature:                                   ORACLE INVESTMENT MANAGEMENT, INC.

                                             By: /s/ Larry N. Feinberg
                                                 ------------------------------
                                                 Name:  Larry N. Feinberg
                                                 Title: President