<PAGE>
                                                                   EXHIBIT 10.20


               EMPLOYMENT SEPARATION AND GENERAL RELEASE AGREEMENT

This Employment Separation and General Release Agreement ("Separation
Agreement") is entered into by and between Michael J. Gerber, M.D. ("Dr.
Gerber"), an individual, and Allos Therapeutics, Inc. ("Allos"), and shall
become effective on the Effective Date as defined in Section 16 below. Dr.
Gerber and Allos may be collectively referred to herein as the "Parties."

                                    RECITALS

A. Effective September 24, 2001, Dr. Gerber has resigned his position as Senior
Vice President, Clinical Development and Regulatory Affairs and any and all
other positions Dr. Gerber may have held with Allos, or any affiliate or
subsidiary of Allos.

B. The Parties wish the make the separation amicable but conclusive on the terms
and conditions set forth herein.

C. Dr. Gerber accepts the benefits of this Separation Agreement with the
acknowledgment that by its terms he has been fully and satisfactorily
compensated.

                                    COVENANTS

In consideration of the mutual covenants and promises set forth in this
Separation Agreement, including Dr. Gerber's general release of claims and
covenant not to sue, the Parties agree as follows:

1. Resignation. Dr. Gerber resigned as Senior Vice President, Clinical
Development and Regulatory Affairs, and any and all other positions Dr. Gerber
may have held with the Allos and any of affiliates or subsidiaries of Allos,
effective as of September 24, 2001, at 5:00 p.m. (the "Separation Date"). Dr.
Gerber acknowledges that he has received payment of all wages and compensation,
including payment for all accrued vacation benefits and bonuses, that he earned
up through the Separation Date, subject to standard payroll deductions and
withholdings.

2. Severance Benefits. As part of the consideration for the mutual covenants and
promises contained in this Separation Agreement, including Dr. Gerber's general
release of claims and covenant not to sue, Dr. Gerber will be eligible to
receive the following severance benefits:

                    a. Severance Pay. Subject to the terms and conditions of
                    this Separation Agreement, Dr. Gerber shall receive
                    severance pay ("Severance Pay") in the gross sum of
                    $256,781.20 which is equal to 52 weeks of his weekly base
                    compensation. The Severance Pay will be subject to all
                    required deductions and tax withholdings. The Severance Pay
                    will be paid in equal installments in accordance with Allos'
                    normal payroll cycle during the 52-week period following the
                    Effective Date of this Agreement as defined in Section 16
                    below.

                    b. Disability Insurance Premiums. Allos shall reimburse Dr.
                    Gerber, on a grossed-up basis, for the premium costs he
                    incurs in continuing in effect the supplemental disability
                    insurance policy under which he is now insured for a period
                    of 24-months following the Separation Date.




<PAGE>




                    c. COBRA Insurance Premiums. For purposes of the
                    Consolidated Omnibus Budget Reconciliation Act, the
                    applicable COBRA period (typically 18 months) will begin
                    September 25, 2001. Pursuant to the terms and conditions of
                    COBRA and Allos' group medical and dental insurance plan,
                    Dr. Gerber may continue his participation and his
                    dependents' participation in Allos' medical and dental
                    insurance plan for the applicable COBRA period by making
                    required COBRA payments. Dr. Gerber acknowledges that Allos
                    has provided him with a COBRA notification setting forth his
                    rights and responsibilities with respect to COBRA coverage.
                    As part of the consideration for the mutual covenants and
                    promises contained in this Separation Agreement, including
                    Dr. Gerber's release of claims and promise not to sue,
                    should Dr. Gerber timely elect to continue medical and
                    dental insurance coverage pursuant to COBRA, Allos agrees to
                    pay Dr. Gerber's COBRA monthly premiums for the period
                    beginning September 25, 2001 and ending September 24, 2002
                    to maintain medical and dental insurance coverage that is
                    similar to that coverage he and his dependents received
                    through Allos immediately prior to the Separation Date.
                    After September 24, 2002, Dr. Gerber will be responsible for
                    paying the COBRA monthly premiums. Notwithstanding the
                    foregoing, Allos' obligation to pay Dr. Gerber's COBRA
                    monthly premiums shall cease immediately upon Dr. Gerber's
                    eligibility for comparable group health insurance provided
                    by a new employer. Dr. Gerber agrees to promptly notify
                    Allos in writing should he become eligible for any medical
                    or dental insurance benefits through a new employer.

                    3. Stock Options.

                    a. As of the Separation Date, Dr. Gerber had the following
                    outstanding options (collectively, the "Options") to
                    purchase shares of Allos' Common Stock:

                            i.            Options to purchase 31,000 shares of
                                          Common Stock pursuant to an Incentive
                                          Stock Option granted on March 4, 1999,
                                          under Allos' 1995 Stock Option Plan
                                          (the "1995 Plan"), of which 31,000
                                          options are vested;

                            ii.           Options to purchase 31,000 shares of
                                          Common Stock pursuant to an Incentive
                                          Stock Option granted on March 4, 1999,
                                          under the 1995 Plan, of which 31,000
                                          options are vested;

                            iii.          Options to purchase 31,000 shares of
                                          Common Stock pursuant to an Incentive
                                          Stock Option granted on May 12, 1999,
                                          under the 1995 Plan, of which 31,000
                                          options are vested;

                            iv.           Options to purchase 85,571 shares of
                                          Common Stock pursuant to an Incentive
                                          Stock Option granted on August 31,
                                          1999, under the 1995 Plan, of which
                                          46,350 options are vested;



                                       2
<PAGE>




                            v.            Options to purchase 67,432 shares of
                                          Common Stock pursuant to a
                                          Non-Qualified Stock Option granted on
                                          August 31, 1999, under the 1995 Plan,
                                          of which 36,525 options are vested;

                            vi.           Options to purchase 31,000 shares of
                                          Common Stock pursuant to a
                                          Non-Qualified Stock Option granted on
                                          August 31, 1999, under the 1995 Plan,
                                          of which 31,000 options are vested;

                            vii.          Options to purchase 31,000 shares of
                                          Common Stock pursuant to a
                                          Non-Qualified Stock Option granted on
                                          August 31, 1999, under the 1995 Plan,
                                          of which zero (0) options are vested;

                            viii.         Options to purchase 36,167 shares of
                                          Common Stock pursuant to a
                                          Non-Qualified Stock Option granted on
                                          January 12, 2000, under the 1995 Plan,
                                          of which zero (0) options are vested;

                            ix.           Options to purchase 41,333 shares of
                                          Common Stock pursuant to an Incentive
                                          Stock Option granted on January 12,
                                          2000, under the 1995 Plan, of which
                                          zero (0) options are vested;

                            x.            Options to purchase 28,500 shares of
                                          Common Stock pursuant to an Incentive
                                          Stock Option granted on March 1, 2001,
                                          under Allos' 2000 Stock Incentive
                                          Compensation Plan (the "2000 Plan"
                                          and, together with the 1995 Plan, the
                                          "Stock Option Plans") of which zero
                                          (0) options are vested; and

                            xi.           Options to purchase 9,500 shares of
                                          Common Stock pursuant to an Incentive
                                          Stock Option granted on July 17, 2001,
                                          under the 2000 Plan, of which zero (0)
                                          options are vested.

                            b. The Parties acknowledge and agree that, upon Dr.
              Gerber's execution of the Consulting Agreement (as defined in
              Section 5 below), the Options shall continue to be governed and
              controlled by the terms and conditions of such Options and the
              applicable Stock Option Plans. Dr. Gerber is advised by Allos to
              seek independent legal advice with respect to tax and securities
              laws regarding his Options, including their status as incentive
              stock options, and any sale of Allos stock that he may wish to
              make, in addition to consulting the applicable Stock Option Plan.

                            c. Except for the occurrence of Dr. Gerber's
              resignation, which Allos intends to publicly announce as soon as
              reasonably practicable following the execution of this Separation
              Agreement, each of Allos and Dr. Gerber hereby represent to the
              other party that they have no knowledge of any material,
              non-public information that would restrict or otherwise affect Dr.
              Gerber ability to exercise any vested Options or sell any shares
              of Allos common stock pursuant to Allos' policies against insider
              trading.



                                       3
<PAGE>

4. Transition Assistance. As part of the consideration for the mutual covenants
and promises contained in this Separation Agreement, including Allos' provision
of the severance benefits pursuant to Section 2 above, Dr. Gerber agrees to
reasonably assist Allos in the transition of his job duties, responsibilities
and knowledge to other Allos employees as reasonably requested by Allos. Dr.
Gerber's obligation to provide such transition assistance shall terminate four
months after the Separation Date and shall be limited to 20 hours each month
during the four month transition period.

5. Consulting Agreement. As part of the consideration for the mutual covenants
and promises contained in this Separation Agreement, including Dr. Gerber's
general release of claims and covenant not to sue, Allos and Dr. Gerber are
simultaneously entering into a consulting agreement, a copy of which is attached
hereto as Exhibit 1 (the "Consulting Agreement").

6. Dr. Gerber's General Release and Covenant Not to Sue. Dr. Gerber, for
himself, his heirs and assigns, does hereby release and discharge Allos and its
present, past and future subsidiaries, divisions, parent and affiliated
companies, and their respective shareholders, directors, officers, employees,
agents, insurers and attorneys (collectively referred to hereafter as the "Allos
Released Parties"), of and from, and promises not to sue or assert against the
Allos Released Parties, for any purpose, all claims, causes of action, damages,
losses, liabilities and demands whatsoever including, but not limited to, any
claim arising from or related to or attributable to Dr. Gerber's employment with
any of the Allos Released Parties and the termination of such employment. This
release includes, but is not limited to, all matters which may arise under
common law or under federal, state, or local laws, including, but not limited
to, all claims under the Age Discrimination in Employment Act, as amended, 29
U.S.C. Sections 621, et seq. ("ADEA"), Title VII of the Civil Rights Act of
1964, as amended, the Civil Rights Act of 1991, the Americans with Disabilities
Act of 1990, the Fair Labor Standards Act, the Worker Adjustment and Retraining
Notification Act ("WARN Act"), the Colorado Antidiscrimination Act, and the
Colorado Wage Claim Act. Dr. Gerber understands and agrees that his release of
claims under this Separation Agreement extends to all claims of every nature and
kind, known and unknown, suspected or unsuspected, presently existing or which
may arise in the future caused by or resulting from or attributable to any act
or omission of the Allos Released Parties occurring prior to Dr. Gerber's
execution of this Separation Agreement. Allos understands and agrees that Dr.
Gerber is not waiving any right or claim which may arise after the date he
executes this Separation Agreement which is based upon any act or omission of
Allos or the Allos Released Parties occurring after his execution of this
Separation Agreement.

7. Dr. Gerber's Acknowledgment Concerning Release of ADEA Claims. Dr. Gerber
expressly acknowledges and agrees that, by entering into this Separation
Agreement, he is waiving any and all rights or claims that he may have under the
Age Discrimination in Employment Act of 1967 ("ADEA"), as amended, which have
arisen on or before the date of his execution of this Separation Agreement. Dr.
Gerber further expressly acknowledges and agrees that:



                                       4
<PAGE>




                    a. In exchange for Dr. Gerber's waiver of any and all rights
                    or claims under the ADEA arising on or before the date of
                    his execution of this Separation Agreement, he will receive
                    consideration in addition to any consideration which he was
                    already entitled to receive before executing this Separation
                    Agreement;

                    b. Dr. Gerber was advised in writing by this Separation
                    Agreement to consult with an attorney of his choice and at
                    his expense prior to his execution of this Separation
                    Agreement;

                    c. A copy of this Separation Agreement was delivered to Dr.
                    Gerber on September 24, 2001, and he was informed in writing
                    by this Separation Agreement that he has twenty-one (21)
                    days within which to consider the Separation Agreement;

                    d. If Dr. Gerber executes this Separation Agreement prior to
                    the expiration of the 21-day period mentioned above, he
                    voluntarily does so thereby waiving the 21-day period; and

                    e. Dr. Gerber was informed that he has seven (7) days
                    following his execution of this Separation Agreement in
                    which to revoke the Separation Agreement.

                    8. Continuing Obligations Under the Non-Competition
                    Agreement and Sections 12 and 13 of the Employment
                    Agreement.

                    a. Subject to the amendment set forth below, Dr. Gerber
                    understands and agrees that notwithstanding the termination
                    of his employment relationship with Allos, he remains
                    subject to the terms and conditions of Sections 12 and 13 of
                    that certain Employment Agreement dated January 17, 2001 by
                    and between Dr. Gerber and Allos (the "Employment
                    Agreement"). The Parties hereby agree that the final
                    sentence of Section 12 of the Employment Agreement shall be
                    amended to read as follows:

                    Accordingly, during the term of Executive's employment and
                    for a period of twelve (12) months immediately following
                    Executive's resignation, Executive shall not without first
                    obtaining the written approval of the Company, directly or
                    indirectly engage or prepare to engage, in any activities in
                    the United States or Canada in competition with the Company,
                    or accept employment or establish a business relationship
                    with a business located in the United Sates or Canada that
                    directly competes with the Company with regard to radiation
                    sensitizers.

                    b. Subject to the amendment set forth below, Dr. Gerber
                    understands and agrees that notwithstanding the termination
                    of his employment relationship with Allos, he remains
                    subject to the terms and conditions of that certain
                    Non-Competition, Proprietary Information and Inventions
                    Agreement attached to the Employment Agreement as Exhibit A
                    (the "Non-Competition Agreement"). The Parties hereby agree
                    that the definition of "Restricted Business" as set forth in
                    Section 5.2(i) of the Non-Competition Agreement shall be
                    amended to read as follows:



                                       5
<PAGE>


                    "Restricted Business" shall mean the research, design,
                    development, marketing or sales of any technology or product
                    that is based upon or utilizes radiation sensitizers.

                    c. Notwithstanding any provisions in this Separation
                    Agreement to the contrary, Allos' obligations to provide
                    severance benefits pursuant to Section 2 above, and Dr.
                    Gerber's rights to receive such severance benefits, shall
                    cease and be rendered a nullity immediately should Dr.
                    Gerber fail to comply with the Non-Competition Agreement and
                    Sections 12 and 13 of the Employment Agreement, as amended
                    herein.

                    9. Return of Allos Property. Dr. Gerber represents and
                    affirms that he has returned to Allos all Allos property in
                    his possession or control including, but not limited to,
                    such items as corporate credit cards, keys, equipment on
                    loan, files, documents, computer hardware and software,
                    computer accessories, manuals, note books, and all other
                    corporate property belonging to Allos.

                    10. Non-Disparagement. As part of the consideration for the
                    mutual covenants and promises contained in this Separation
                    Agreement, (i) Allos agrees not to disparage or otherwise
                    make negative statements or comments about or relating to
                    Dr. Gerber; and (ii) Dr. Gerber agrees not to disparage or
                    otherwise make negative statements or comments about or
                    relating to Allos, the Allos Released Parties, Allos'
                    products and services, investigators who collaborate with
                    Allos on its products, and analysts who analyze Allos'
                    business. This provision is a material term of this
                    Separation Agreement and Dr. Gerber understands that Allos'
                    willingness to provide him with the severance benefits set
                    forth in Section 2 above is based, in part, on his agreement
                    to comply with the requirements of this Section 10. Thus,
                    notwithstanding any provisions in this Separation Agreement
                    to the contrary, Allos' obligations to provide severance
                    benefits pursuant to Section 2 above, and Dr. Gerber's
                    rights to receive such severance benefits, shall cease and
                    be rendered a nullity immediately should Dr. Gerber fail to
                    comply with this Section 10.

                    11. Non-Solicitation and Non-Interference. In addition to
                    his obligations under the Non-Competition Agreement, Dr.
                    Gerber agrees that during the period he is receiving the
                    Severance Pay under Section 2 above, he will not (i)
                    directly or indirectly interfere with Allos' relationship
                    with any employee, consultant, investor, shareholder,
                    investigator, or analyst, (ii) directly or indirectly hire
                    or attempt to hire any employee or consultant of Allos to
                    work for any person, firm or entity of or for which Dr.
                    Gerber is an officer, director, employee, consultant or
                    owner of equity or other financial interest, or (iii)
                    directly or indirectly assist any other person or entity in
                    employing or soliciting for employment any employee or
                    consultant of Allos. This provision is a material term of
                    this Separation Agreement and Dr. Gerber understands that
                    Allos' willingness to provide him with the severance
                    benefits set forth in Section 2 above is based, in part, on
                    his agreement to comply with the requirements of this
                    Section 11. Thus, notwithstanding any provisions in this
                    Separation Agreement to the contrary, Allos' obligations to
                    provide severance benefits pursuant to Section 2 above, and
                    Dr. Gerber's rights to receive such severance benefits,
                    shall cease and be rendered a nullity immediately should Dr.
                    Gerber fail to comply with his obligations under this
                    Section 11.



                                       6
<PAGE>

12. Confidentiality. The provisions of this Separation Agreement shall be held
in strictest confidence by Dr. Gerber and Allos and shall not be publicized or
disclosed in any manner whatsoever. Each of Dr. Gerber and Allos acknowledges,
represents and agrees that he or it, respectively, has not and will not disclose
the terms or provisions of this Separation Agreement to any current, former or
future employee of Allos, or of any of its subsidiaries, divisions, and
affiliates, other than, in the case of Allos, officers or employees who have a
need to know in connection with the performance of their duties. Notwithstanding
the prohibitions contained in this Section 12: (i) the Parties may disclose this
Separation Agreement in confidence to their respective legal and financial
advisors (and family members in the case of Dr. Gerber), each of whom shall be
advised of and be required to adhere to this Separation Agreement's
confidentiality requirement, (ii) Allos may disclose this Separation Agreement
as necessary to fulfill standard or legally required corporate or securities law
reporting or disclosure requirements or to comply with standard due diligence
requests in connection with any financings, mergers or acquisitions, or other
business transactions; (iii) Allos may disclose this Separation Agreement upon
request from any governmental entity; and (iv) the Parties may disclose this
Separation Agreement insofar as disclosure may be necessary to enforce one or
more terms of this Separation Agreement. This provision is a material term of
this Separation Agreement and Dr. Gerber understands that Allos' willingness to
provide him with the severance benefits set forth in Section 2 above is based,
in part, on his agreement to comply with the requirements of this Section 12.
Thus, notwithstanding any provisions in this Separation Agreement to the
contrary, Allos' obligations to provide severance benefits pursuant to Section 2
above, and Dr. Gerber's rights to receive such severance benefits, shall cease
and be rendered a nullity immediately should Dr. Gerber fail to comply with his
obligations under this Section 12.

13. Opportunity to Review and Consider Separation Agreement. Dr. Gerber
acknowledges that a copy of this Separation Agreement was delivered to him on
September 24, 2001, and that he has been given a period of 21 calendar days to
review, analyze and consider this Separation Agreement before signing it. Dr.
Gerber further acknowledges that he understands this Separation Agreement in its
entirety.

14. Right to Revoke Separation Agreement. Dr. Gerber may revoke this Separation
Agreement, and, in particular, may revoke his waiver of any and all rights or
claims under the ADEA arising on or before the date of his execution of this
Separation Agreement, during the seven (7) days following his execution of this
Separation Agreement. Any revocation of this Separation Agreement must be in
writing and hand-delivered during the revocation period to Barbara Baring,
Allos' Vice President of Human Resources.

15. Legal Advice. Dr. Gerber acknowledges that he has been advised to consult
with an attorney of his own choice and at his own expense before executing this
Separation Agreement and that he has been given an opportunity to do so.



                                       7
<PAGE>

16. Effective Date. The Effective Date of this Separation Agreement shall be the
eighth day after Dr. Gerber signs and returns this Separation Agreement to Allos
so long as he does not exercise his right to revoke this Separation Agreement as
set forth in Section 12 above. In the event Dr. Gerber fails to sign and return
this Separation Agreement to Allos on or before October 17, 2001, or revokes
this Separation Agreement within 7 days after he signs it, this Separation
Agreement and the attached Consulting Agreement will be null and void.

17. Miscellaneous.

                    a. Modification/Waiver. This Separation Agreement may not be
                    amended, modified, superseded, canceled, renewed or
                    expanded, or any terms or covenants hereof waived, except by
                    a writing executed by each of the Parties hereto or, in the
                    case of a waiver, by the party waiving compliance. Failure
                    of any party at any time or times to require performance of
                    any provision hereof shall in no manner affect his or its
                    right at a later time to enforce the same. No waiver by a
                    party of a breach of any term or covenant contained in this
                    Separation Agreement, whether by conduct or otherwise, in
                    any one or more instances shall be deemed to be or construed
                    as a further or continuing waiver of agreement contained in
                    the Separation Agreement.

                    b. Entire Agreement. This Separation Agreement, the
                    Consulting Agreement, the Non-Competition Agreement and
                    Sections 12 and 13 of the Employment Agreement constitute
                    and contain the entire agreement and understanding between
                    the Parties concerning the subject matters addressed herein
                    and therein and supersedes and replaces all prior
                    negotiations and agreements, proposed or otherwise, whether
                    written or oral, concerning the subject matters of this
                    Separation Agreement. By way of example, and without
                    limitation, this Separation Agreement supersedes Section 9
                    of the Employment Agreement, and this Separation Agreement
                    extinguishes Allos' obligation to provide Dr. Gerber with
                    any severance benefits under the Employment Agreement.

                    c. Severability. If any provision of this Separation
                    Agreement or any application thereof is held invalid, the
                    invalidity shall not affect other provisions or applications
                    of this Separation Agreement which can be given effect
                    without the invalid provision or application.

                    d. Notices. All notices given hereunder shall be given by
                    certified mail, addressed, or delivered by hand, to the
                    other party at his or its address as set forth below, or at
                    any other address hereafter furnished by notice given in
                    like manner. Dr. Gerber promptly shall notify Allos of any
                    change of his address. Each notice shall be dated the date
                    of its mailing or delivery and shall be deemed given,
                    delivered or completed on such date.



                                       8
<PAGE>




                    Michael J. Gerber, MD
                    500 Clermont Street
                    Denver, CO 80220

                    Allos  Therapeutics, Inc.
                    Attn:  Stephen J. Hoffman, MD
                    President, Chief Executive Officer
                    11080 CirclePoint Road
                    Westminster, CO 80020

          e. Governing Law; Personal Jurisdiction and Venue; Enforcement. This
          Separation Agreement and all disputes relating to this Separation
          Agreement shall be governed in all respects by the laws of the State
          of Colorado as such laws are applied to agreements between Colorado
          residents entered into and performed entirely in Colorado. The Parties
          acknowledge that this Separation Agreement constitutes the minimum
          contacts to establish personal jurisdiction in Colorado and agree to
          Colorado court's exercise of personal jurisdiction. The Parties
          further agree that any dispute relating to this Agreement shall be
          brought in a court located in the State of Colorado and that the
          prevailing party in such a dispute shall be entitled to an award of
          his or its costs and expenses incurred in such dispute, including his
          or its reasonable attorney's fees, in addition to any other relief to
          which the party may be entitled.

          f. Counterparts. This Separation Agreement may be executed by
          facsimile signature and may be executed in several counterparts, each
          of which shall be deemed an original and all of which taken together
          shall constitute a single instrument. Photographic copies of such
          executed counterparts may be used in lieu of the original for any
          purpose.

          DR. GERBER AND ALLOS HEREBY ACKNOWLEDGE THAT THEY HAVE READ THIS
          SEPARATION AGREEMENT, THAT THEY FULLY UNDERSTAND ITS FINAL AND BINDING
          EFFECT, THAT THE ONLY PROMISES MADE TO THEM TO SIGN THIS SEPARATION
          AGREEMENT ARE THOSE STATED ABOVE, AND THAT THEY ARE SIGNING THIS
          SEPARATION AGREEMENT VOLUNTARILY.

                 [Remainder of page is intentionally left blank]



                                       9
<PAGE>


IN WITNESS WHEREOF, the undersigned parties have executed this Agreement as of
the 3rd day of October, 2001.

                                         ALLOS THERAPEUTICS, INC.

                                         By: /s/ STEPHEN J. HOFFMAN
                                            -----------------------------------
                                            Stephen J. Hoffman, MD
                                            President, Chief Executive Officer

STATE OF COLORADO               )
                                )     ss
COUNTY OF BROOMFIELD            )

The foregoing instrument was acknowledged before me this 16th day of November,
2001, by Stephen J. Hoffman MD, as President, Chief Executive Officer of Allos
Therapeutics, Inc.

           Witness my hand and official seal.

           My commission expires:

                                                        /s/ SHARON A. SMITH
                                                            Notary Public

                                                      /s/ MICHAEL J. GERBER
                                                      MICHAEL J. GERBER, M.D.



STATE OF COLORADO               )
                                )     ss
COUNTY OF DENVER                )

The foregoing instrument was acknowledged before me this 16th day of November,
2001, by Michael J. Gerber, M.D.

           Witness my hand and official seal.

           My commission expires:  6/10/2002
                                                        /s/ MILDRED C. MORIE
                                                            Notary Public



                                       10
<PAGE>




                                   EXHIBIT ONE

                              CONSULTING AGREEMENT

This Consulting Agreement ("Consulting Agreement") is made and entered into
effective this 24th day of September, 2001, by and between Allos Therapeutics,
Inc., a Delaware corporation (the "Company"), located at 11080 CirclePoint Road,
Westminster, CO 80020, and Michael J. Gerber, M.D. ("Consultant"). The Company
and the Consultant may be collectively referred to herein as the "Parties."

                                    RECITALS

A. Consultant has been employed by the Company since July 1994 and was a party
to an employment agreement with the Company dated January 17, 2001.

B. The Parties are terminating their employment relationship pursuant to an
Employment Separation and General Release Agreement (the "Separation
Agreement"). As part of the Separation Agreement, Consultant is required to
provide certain transition assistance to the Company by assisting in the
transition of his job duties, responsibilities and knowledge to other Company
employees. Consultant is required to provide this transition assistance for up
to 20 hours per month during the four-month period immediately following the
termination of the Parties' employment relationship.

C. The Company would like to retain Consultant to provide certain consulting
services relating to his areas of expertise and Consultant is willing to provide
such consulting services. The Parties understand and agree that the consulting
services will be independent of and separate from the transition assistance
Consultant is required to provide under the Separation Agreement. The Parties
are thus entering into this Consulting Agreement to govern their rights and
obligations with respect to Consultant's provision of such consulting services.

                                    AGREEMENT

In consideration of the mutual promises and covenants contained herein, the
Parties agree as follows:

1. Term of Agreement: Unless sooner terminated in accordance with Section 9
below, this Consulting Agreement shall remain in full force and effect and shall
bind the Parties for a period of one year from the effective date hereof. The
Parties may renew this Consulting Agreement for additional periods upon mutual
written agreement.



                                        2
<PAGE>


2. Consultant Obligations: As requested from time to time by the Company's
executive officers, Consultant shall provide consulting services (the
"Consulting Services") which relate to his areas of expertise and which the
Company's executive officers believe would be beneficial to the Company. The
specific nature and amount of the Consulting Services that Consultant may be
requested to perform by the Company under this Consulting Agreement shall be
within the sole discretion of the Company. Consultant shall perform the
Consulting Services at his offices unless otherwise agreed to by the Parties.
Consultant agrees to make himself available to provide the Consulting Services
at the times reasonably requested by the Company; provided that, the Company
will reasonably cooperate with Consultant in the event that he has conflicts in
connection with his other obligations, whether such obligations are work related
or personal.

3. Company Obligations: The Company shall compensate Consultant at the rate of
$2,500 per day for the time he actually spends in providing the Consulting
Services. A "day" for purposes of this Consulting Agreement shall mean not less
than eight hours spent during a given day in the performance of the Consulting
Services. In the event Consultant spends less than eight hours during a given
day providing the Consulting Services, he shall be compensated on a prorated
basis for that day (i.e., If Consultant spends five hours on a given day
providing the Consulting Services, he shall be compensated for that day at the
rate of 5/8 x $2,500). With respect to travel time, Consultant shall be
compensated only for time spent actually performing the Consulting Services; he
shall not be compensated for travel time during which Consulting Services are
not performed. In addition, the Company shall provide reimbursement at cost for
those reasonable expenses incurred by Consultant in performing the Consulting
Services, such as long distance telephone calls, actual travel costs at the
lowest available rate for 7-day advanced fare purchases (unless the Company
requests Consultant to travel on less than 7 days' notice), and materials
requested by the Company. Reasonably detailed invoices, together with
accompanying documentation regarding any expenses for which reimbursement is
sought, shall be submitted on at least a monthly basis and payment will be
forwarded no later than 30 days after receipt of the invoice. Consulting
services shall be compensated pursuant to the foregoing provisions both during
the four 4 month transition period and during the entire term of this Agreement.
The Consultant shall not be required to provide more than 20 hours of
non-compensated transition services during each of the first 4 months and,
accordingly, all hours in excess of 20 in each such month shall be deemed
consulting.



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<PAGE>




          4. Independent Contractor:

          a) Consultant's relationship with the Company is that of an
          independent contractor, and nothing in this Consulting Agreement
          should be construed to create a partnership, joint venture, or
          employer-employee relationship. Consultant is not the agent of the
          Company and is not authorized to make any representation, contract, or
          commitment on behalf of Company without the written consent of an
          officer of the Company. Consultant will not be entitled to any of the
          benefits which the Company may make available to its employees, such
          as group insurance, profit-sharing, or retirement benefits. The
          Consultant will be solely responsible for all tax returns and payments
          required to be filed with or made to any federal, state or local tax
          authority with respect to Consultant's performance of the Consulting
          Services and his receipt of fees under this Consulting Agreement. The
          Company will regularly report amounts paid to Consultant by filing
          Form 1099-MISC with the Internal Revenue Service as required by law.
          Because Consultant is an independent contractor, the Company will not
          withhold or make payments for social security; make unemployment
          insurance or disability insurance contributions; or obtain worker's
          compensation insurance on Consultant's behalf. Consultant agrees to
          accept exclusive liability for complying with all applicable state and
          federal laws governing self-employed individuals, including
          obligations such as payment of taxes, social security, disability and
          other contributions based on fees paid to Consultant, his agents or
          employees under this Consulting Agreement.

          b) Consultant acknowledges that if he is injured while performing the
          Consulting Services hereunder, he will not be covered for such injury
          under the Company's insurance policies, including under any Worker's
          Compensation coverage provided by the Company for its employees.
          Consultant further acknowledges that he is solely responsible for
          providing Worker's Compensation insurance for any of his employees.

          5. Other Activities: Consultant is free to enter into any contract to
          provide consulting services to other businesses, entities, or
          individuals, during the term of this Consulting Agreement, unless such
          contract would violate the provisions of this Consulting Agreement or
          the Separation Agreement, would induce Consultant to breach any
          provision of this Consulting Agreement or the Separation Agreement, or
          would prevent or restrict Consultant from satisfying Consultant's
          obligations under this Consulting Agreement.

          6. Stock Options: For so long as this Consulting Agreement remains in
          effect, Consultant's Options shall continue to vest pursuant to the
          terms of the Options and the applicable Stock Option Plans. The
          Parties acknowledge and agree that upon the termination of this
          Consulting Agreement, (i) Dr. Gerber will have ninety (90) days
          following the date of such termination (the "Termination Date") to
          exercise all Options (as defined in Section 3 of the Separation
          Agreement) which are vested as of the Termination Date; and (ii) all
          Options which have not vested as of the Termination Date will
          terminate and revert to the Company as of the Termination Date, all in
          accordance with the terms and conditions of such Options and the
          applicable Stock Option Plan (as defined in Section 3 of the
          Separation Agreement). The Parties further acknowledge and agree that,
          Dr. Gerber is advised by the Company to seek independent legal advice
          with respect to tax and securities laws regarding his Options and any
          sale of Company stock he may wish to make, in addition to consulting
          the terms and conditions of the Options and the Stock Option Plans.



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<PAGE>


          7. Proprietary Information:

          a) In addition to his obligations under the Separation Agreement,
          Consultant agrees that he shall not, at any time during the term of
          this Consulting Agreement and for a period of ten years thereafter,
          whether or not in the employ of the Company, disclose, communicate, or
          divulge to, or use for his personal benefit or for the benefit of any
          person, firm, association, or corporation other than the Company, any
          reproductions or materials of any kind, any proprietary information,
          knowledge, or information with respect to techniques used by the
          Company in connection with its operations, any business methods,
          business policies or any other information relating to or dealing with
          the policies or practices of the Company, made known to Consultant by
          the Company or any of its officers or employees, or learned by
          Consultant while in the employ of the Company or communicated to or
          acquired by Consultant while in the employment of Company without the
          prior written consent of Company. Consultant further covenants and
          agrees that the termination of this Consulting Agreement shall not
          release Consultant from the foregoing obligations, and that such
          knowledge or information which Consultant has obtained or may obtain
          in the course of providing the Consulting Services under this
          Consulting Agreement will be kept confidential for such ten-year
          period and not revealed to any competitor firms, corporations,
          associations, and other persons whatsoever.

          b) Upon the expiration or earlier termination of this Consulting
          Agreement, Consultant covenants and agrees to deliver to the Company
          any articles or papers which have come into Consultant's possession
          during the performance of the Consulting Services for the Company or
          which Consultant holds for the Company irrespective of whether such
          data, lists, papers, or records were prepared by Consultant or not.

          8. Allos Inventions: The Consultant agrees that the Company has
          exclusive rights and ownership to any ideas, inventions, writings or
          other developments conceived or contributed to or by Consultant as
          part of his provision of the Consulting Services to the Company. At
          the request of the Company, Consultant will assist in executing any
          documents reasonably required to confirm any proprietary rights or
          patents that the Company may pursue. By entering into this Consulting
          Agreement, Consultant acknowledges that he will return any and all
          Company property or materials in his possession at the termination of
          this Consulting Agreement or at the request of the Company.



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<PAGE>




9. Termination: Notwithstanding any provisions in this Consulting Agreement to
the contrary, this Consulting Agreement and Consultant's status as a consultant
shall automatically terminate upon any of the following occurrences:

          a) Consultant's material breach of any provision of this Consulting
          Agreement that is not remedied within 30 days after written notice of
          such breach is provided to Consultant by the Company's Board of
          Directors;

          b) Consultant's breach of any provision of the Separation Agreement;

          c) Consultant's failure to sign the Separation Agreement on or before
          October 17, 2001;

          d) Consultant's revocation of the Separation Agreement at any time
          during the eight day period after he signs it;

          e) The initiation of any legal proceeding or administrative action by
          Consultant against the Company; or

          f) Written notice by Consultant to the Company that he wishes to
          terminate this Consulting Agreement.

          10. Severability: If any provision of this Consulting Agreement or any
          application thereof is held invalid, the invalidity shall not affect
          other provisions or applications of this Consulting Agreement which
          can be given effect without the invalid provision or application.

          11. Entire Agreement: This Consulting Agreement and the Separation
          Agreement constitute and contain the entire agreement and
          understanding between the Parties concerning the subject matters
          addressed herein and supersede and replace all prior negotiations and
          agreements, proposed or otherwise, whether written or oral, concerning
          the subject matters of this Consulting Agreement. This Consulting
          Agreement shall not be altered, amended, or changed except by a
          writing executed by each of the Parties hereto or, in the case of a
          waiver, by the party waiving compliance.

          12. Governing Law; Personal Jurisdiction and Venue; Enforcement. This
          Consulting Agreement and all disputes relating to this Consulting
          Agreement shall be governed in all respects by the laws of the State
          of Colorado as such laws are applied to agreements between Colorado
          residents entered into and performed entirely in Colorado. The Parties
          acknowledge that this Consulting Agreement constitutes the minimum
          contacts to establish personal jurisdiction in Colorado and agree to
          Colorado courts' exercise of personal jurisdiction. The Parties
          further agree that any dispute relating to this Consulting Agreement
          shall be brought in a court located in the State of Colorado and that
          the prevailing party in such a dispute shall be entitled to an award
          of his or its costs and expenses incurred in such dispute, including
          his or its reasonably attorney's fees, in addition to any other relief
          to which the party may be entitled.

          13. Assignment: This Consulting Agreement and the rights and
          obligations hereunder shall be and hereby are non-assignable in whole
          or in part by Consultant. It is understood and agreed that Consultant
          shall not be permitted to assign, subcontract or appoint any agent or
          subagent for the performance of any part of his duties and obligations
          hereunder. This Consulting Agreement shall otherwise be binding upon
          and inure to the benefit of the successors and assigns of the Parties
          hereto.



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<PAGE>




IN WITNESS WHEREOF, this Agreement has been executed as of the date set forth
above.

Allos Therapeutics, Inc.                        CONSULTANT

/s/ STEPHEN J. HOFFMAN                          /s/ MICHAEL J. GERBER
Stephen J. Hoffman, MD                          Signature

Title: President, Chief Executive Officer       Date:  11/16/01

Date:  11/16/01                                 Social Security No.: ###-##-####



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