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                                                                   EXHIBIT 10.15

                                THIRD AMENDMENT
                     TO 7000 BROADWAY BUILDING OFFICE LEASE
                                    between
                    DENVER JACK LIMITED PARTNERSHIP (Lessor)
                                      and
            ALLOS THERAPEUTICS, INC., a Delaware Corporation (Lessee)
                              Dated March 26, 1998

THIS THIRD AMENDMENT is to that certain office lease (the "Lease") dated October
30, 1995, First Amendment to 7000 Broadway Building Office Lease dated October
30, 1995 and Second Amendment to 7000 Broadway Building Office Lease dated June
7, 1996, by and between Denver Jack Limited Partnership ("Lessor") and Allos
Therapeutics, Inc., a Delaware Corporation ("Lessee") with respect to
approximately 4,022 and 2,308 square feet of space on the 3rd floor, known as
Suite 310 and 320 (the "Premises"), in the building known as 7000 Broadway,
Denver, Colorado (the "Building"). In the event of any conflict between the
terms and provisions of the Lease as amended by the First and Second Amendments,
and the terms and provisions of this Third Amendment, the terms and provisions
of this Third Amendment shall control.

     1.   Amendment to Article 34 of Rider Number One to the Lease Document and
          Article 1 of the Second Amendment. Lessor and Lessee do hereby agree
          that effective July 1, 1998 or when Landlord delivers Premises to
          Tenant (the "Effective Date") the description of the Premises shall be
          deemed to be amended to include approximately 9,208 rentable square
          feet of office space located on the fourth (4th) floor known as Suite
          400 (the "New Premises") as outlined on the diagram of the fourth
          (4th) floor of the building, attached hereto as Exhibit "A".

          As of the Effective Date, Lessee shall be released of its obligation
          from suite 310 excluding the shower area consisting of approximately
          3,810 rentable square feet leaving approximately 2,520 rentable square
          feet in suite 320 and shower area ("suite 320").

          Lessee's right to occupy and obligation to pay Base Rent on the "New
          Premises" shall commence on the "Effective Date" and shall terminate
          with the lease term which is redefined in paragraph 2 of this Third
          Amendment.

          Except as otherwise specifically provided herein, as of the "Effective
          Date" any reference to the term "Premises" and/or "New Premises" in
          the Lease or any amendments thereto, including this Amendment, shall
          be known as suite 400, approximately 9,208 rentable square feet and
          suite 320, approximately 2,520 rentable square feet and Lessee's
          occupancy thereof shall be subject to all of the terms and conditions
          of the Lease.

     2.   Amendment to Article 1 of the Lease Document and Article 2 of the
          Second Amendment. Lessor and Lessee do hereby agree that as of the
          "Effective Date", the lease term as described in Article 1 of the
          Lease and Article 2 of the Second Amendment shall remain the same for
          suite 320 and shall be extended through April 30, 2002 for suite 400.


     3.   Amendment to Article 35 of Rider Number One to the Lease document and
          Article 3 of the Second Amendment. As of the "Effective Date", Lessor
          and Lessee do hereby agree that the Rent obligation in Article 35 of
          Rider Number One and Article 3 of the Second Amendment to the lease
          document be amended as outlined below:

               Suite 400 Approximately 9,208 Rentable Square Feet
               --------------------------------------------------

<TABLE>
<S>                           <C>                           <C>
07/01/98 - 06/30/99           $10,359.00 per month          ($13.50 RSF/Yr)
07/01/99 - 06/30/00           $10,550.83 per month          ($13.75/RSF/Yr)
07/01/00 - 06/30/01           $10,934.50 per month          ($14.25/RSF/Yr)
07/01/01 - 06/30/02           $11,126.33 per month          ($14.50 RSF/Yr)
</TABLE>

               Suite 320 Approximately 2,520 Rentable Square Feet
               --------------------------------------------------

<TABLE>
<S>                           <C>                           <C>
07/01/98 - 12/31/98           $2,541.00 per month           ($12.10/RSF/Yr)
01/01/99 - 06/30/01           $2,608.20 per month           ($12.42/RSF/Yr)
</TABLE>








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          Such other charges as may be required by the terms of this Lease to be
          paid by Lessee may be referred to in the Lease document as "Additional
          Rent." Lessor shall have the same rights as to the Additional Rent as
          it has to the payment of the rent set forth above.

          All payments are due on or before the first day of the first full
          calendar month of the term hereof and a like sum on or before the
          first day of each and every successive calendar month thereafter
          during the term hereof. Rent for any period during the term hereof,
          which is less than one month, shall be prorated based on a thirty (30)
          day calendar month. All rents payable hereunder shall be paid to
          Lessor in lawful money of the United States of America constituting
          legal tender at the time of payment, at the office of the building or
          to such other person at such other place as Lessor may, from time to
          time, designate in writing. The current payments or notice to Lessor
          shall be c/o CB Commercial Real Estate Group, Inc., 1050 Seventeenth
          Street, Suite 800, Denver, Colorado 80265.

     4.   Lessee Improvements. Lessor shall provide "turnkey" Lessee
          improvements with building standard materials per the attached Exhibit
          "A" prepared by McDermott Planning dated March 26, 1998. Any increase
          in cost of the Lessee improvements due to Lessee changing, modifying
          or altering the plan shall be the responsibility of Lessee.

     5.   Amendment to Article 39 of Rider Number One to the Lease Document and
          Article 5 of the Second Amendment. As of the Effective Date, Lessee
          shall have the right to use on an unassigned, unreserved basis, one
          (1) parking space for every 200 rentable square feet leased in the
          7000 Broadway parking area free of charge for the term of the Lease.

     6.   Amendment to Article 38 of Rider Number One of the Lease Document and
          Article 6 of the Second Amendment. Lessee's percentage of Operating
          Expenses as of the "Effective Date" shall be 5.54% for suite 320 and
          20.27% for suite 400.

     7.   Moving Allowance. Lessor shall provide Lessee with up to $18,416.00 to
          offset costs associated with moving of furniture, equipment,
          telecommunications and data communications lines, and changing of
          letterhead. Said allowance shall be paid to Lessee upon Lessee's
          furnishing original receipts of each expense to Lessor.

     8.   Conflicts. If there is any conflict between the terms and provisions
          of this Third Amendment and the terms and provisions of the Lease as
          amended by the First and Second Amendments, the terms and provisions
          of this Third Amendment shall govern. Except as herein specifically
          set forth, all other provisions of the Lease shall remain in full
          force and effect and be binding upon the parties in accordance with
          their terms.

LESSOR:                                      LESSEE:

AMBERJACK, LTD., GENERAL PARTNER FOR         ALLOS THERAPEUTICS
DENVER JACK LIMITED PARTNERSHIP BY           A DELAWARE CORPORATION
CB COMMERCIAL REAL ESTATE GROUP,  INC.,
AS MANAGER

By:  /s/  [ILLEGIBLE]                        By:  /s/  Stephen J. Hoffman
     ---------------------------------            -----------------------------

Its:   Vice President                        Its:   CEO
     ---------------------------------            -----------------------------

By:  /s/  [ILLEGIBLE]                        By:
     ---------------------------------            -----------------------------

Its:   SVP                                   Its:
     ---------------------------------            -----------------------------

STATE OF COLORADO

COUNTY OF ADAMS

The foregoing instrument was acknowledge before me this 7th day of
April, 1998 by Stephen J. Hoffman as CEO.

Witness my hand and official seal.

My commission expires: 5/2/99

                                       /s/     LISA D. LANGE
                                       -------------------------------
                                       Notary Public
(SEAL)
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                                 CB COMMERCIAL










                                 [EXHIBIT "A"]









                                ALLOS SPACE PLAN


NOT TO SCALE                                                [NORTH LOGO]
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                                  [FLOOR PLAN]















                                 [EXHIBIT "B"]