Exhibit 10.4

ALLOS THERAPEUTICS, INC.  2001 EMPLOYEE STOCK PURCHASE PLAN

Adopted by the Board of Directors: February 28, 2001
Approved by Stockholders: April 27, 2001
Amended and Restated: December 13, 2010

1.     PURPOSE.

(a)The purpose of the Plan is to provide a means by which Employees of the Company and certain designated Related
Corporations may be given an opportunity to purchase shares of the Common Stock of the Company.

(b)The Company, by means of the Plan, seeks to retain the services of such Employees, to secure and retain the services of
new Employees and to provide incentives for such persons to exert maximum efforts for the success of the Company and its Related Corporations.

(c)The Company intends that the Purchase Rights granted under the Plan be considered options issued under an Employee Stock
Purchase Plan.

2.     DEFINITIONS.

(a)"Board"means the Board of Directors of the Company.

(b)"Code"means the Internal Revenue Code of 1986, as amended.

(c)"Committee"means a committee appointed by the Board in accordance with
Section 3(c) of the Plan.

(d)"Common Stock"means the common stock of the Company.

(e)"Company"means Allos Therapeutics, Inc., a Delaware corporation.

(f)"Corporate Transaction"means the occurrence, in a single transaction or
in a series of related transactions, of any one or more of the following events:



(g)"Director"means a member of the Board.

(h)"Eligible Employee"means an Employee who meets the requirements set
forth in the Offering for eligibility to participate in the Offering, provided that such Employee also meets the requirements for eligibility to participate set forth in the Plan.

(i)"Employee"means any person, including Officers and Directors, who is
employed for purposes of Section 423(b)(4) of the Code by the Company or a Related Corporation. Neither service as a Director nor payment of a director's fee shall be sufficient to make an
individual an Employee of the Company or a Related Corporation.

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(j)"Employee Stock Purchase Plan"means a plan that grants Purchase Rights
intended to be options issued under an "employee stock purchase plan," as that term is defined in Section 423(b) of the Code.

(k)"Exchange Act"means the Securities Exchange Act of 1934, as amended.

(l)"Fair Market Value"means the value of a security, as determined in good
faith by the Board. If the security is listed on any established stock exchange or traded on the Nasdaq National Market or the Nasdaq SmallCap Market, the Fair Market Value of the security, unless
otherwise determined by the Board, shall be the closing sales price (rounded up where necessary to the nearest whole cent) for such security (or the closing bid, if no sales were reported) as quoted
on such exchange or market (or the exchange or market with the greatest volume of trading in the relevant security of the Company) on the relevant determination date (or if the relevant determination
date does not fall on a Trading Day, the Trading Day prior to the relevant determination date), as reported in The Wall Street Journal or such other source as the Board deems reliable.

(m)"Offering"means the grant of Purchase Rights to purchase shares of
Common Stock under the Plan to Eligible Employees.

(n)"Offering Date"means a date selected by the Board for an Offering to
commence.

(o)"Officer"means a person who is an officer of the Company within the
meaning of Section 16 of the Exchange Act and the rules and regulations promulgated thereunder.

(p)"Participant"means an Eligible Employee who holds an outstanding
Purchase Right granted pursuant to the Plan.

(q)"Plan"means this Allos Therapeutics, Inc. 2001 Employee Stock
Purchase Plan.

(r)"Purchase Date"means one or more dates during an Offering established by
the Board on which Purchase Rights granted under the Plan shall be exercised and as of which purchases of shares of Common Stock shall be carried out in accordance with such Offering.

(s)"Purchase Period"means a period of time specified within an Offering
beginning on the Offering Date or on the next day following a Purchase Date within an Offering and ending on a Purchase Date, at the end of which there shall be purchased shares of Common Stock on
behalf of Participants. An Offering may consist of one or more Purchase Periods.

(t)"Purchase Right"means an option to purchase shares of Common Stock
granted pursuant to the Plan.

(u)"Related Corporation"means any parent corporation or subsidiary
corporation, whether now or hereafter existing, as those terms are defined in Sections 424(e) and (f), respectively, of the Code.

(v)"Securities Act"means the Securities Act of 1933, as amended.

(w)"Trading Day"means any day the exchange(s) or market(s) on which shares
of Common Stock are listed, whether it be any established stock exchange, the Nasdaq National Market, the Nasdaq SmallCap Market or otherwise, is open for trading.

3.     ADMINISTRATION.

(a)The Board shall administer the Plan unless and until the Board delegates administration to a Committee, as provided in
Section 3(c). Whether or not the Board has delegated administration, the Board shall have the final power to determine all questions of policy and expediency that may arise in the
administration of the Plan.

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(b)The Board (or the Committee) shall have the power, subject to, and within the limitations of, the express provisions of
the Plan:



(c)The Board may delegate administration of the Plan to a Committee of the Board composed of one (1) or more members
of the Board. If administration is delegated to a Committee, the Committee shall have, in connection with the administration of the Plan, the powers theretofore possessed by the Board, subject,
however, to such resolutions, not inconsistent with the provisions of the Plan, as may be adopted from time to time by the Board. The Board may abolish the Committee at any time and revest in the
Board the administration of the Plan. If administration is delegated to a Committee, references to the Board in this Plan and in the Offering document shall thereafter be deemed to be to the Board or
the Committee, as the case may be.

4.     SHARES OF COMMON STOCK SUBJECT TO THE PLAN.

(a)Subject to the provisions of Section 14 relating to adjustments upon changes in stock, the shares of Common Stock
that may be sold pursuant to Purchase Rights granted under the Plan shall not exceed in the aggregate two million five hundred thousand (2,500,000) shares of Common Stock. If any Purchase Right
granted under the Plan shall for any reason terminate without having been exercised, the shares not purchased under such Purchase Right shall again become available for issuance under the Plan.

(b)The shares of Common Stock subject to the Plan may be unissued shares or shares that have been bought on the open market
at prevailing market prices or otherwise.

5.     GRANT OF PURCHASE RIGHTS; OFFERING.

(a)The Board may from time to time grant or provide for the grant of Purchase Rights to purchase shares of Common Stock
under the Plan to Eligible Employees in an Offering (consisting of one or more Purchase Periods) on an Offering Date or Offering Dates selected by the Board. Each Offering shall be in such form and
shall contain such terms and conditions as the Board shall deem appropriate, which shall comply with the requirement of Section 423(b)(5) of the Code that all Employees granted Purchase Rights
to purchase shares of Common Stock under the Plan shall have the same rights and privileges. The terms and conditions of an Offering shall be incorporated by reference into the Plan and treated as
part of the Plan. The provisions of separate Offerings need not be identical, but each Offering shall include (through incorporation of the provisions of this Plan by reference in the document
comprising the Offering or otherwise) the period during which the Offering shall be effective, which period shall not exceed twenty-seven (27) months beginning with the Offering Date, and the
substance of the provisions contained in Sections 6 through 9, inclusive.

(b)If a Participant has more than one Purchase Right outstanding under the Plan, unless he or she otherwise indicates in
agreements or notices delivered hereunder: (i) each agreement or notice

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delivered
by that Participant shall be deemed to apply to all of his or her Purchase Rights under the Plan, and (ii) a Purchase Right with a lower exercise price (or an earlier-granted Purchase
Right, if different Purchase Rights have identical exercise prices) shall be exercised to the fullest possible extent before a Purchase Right with a higher exercise price (or a later-granted Purchase
Right, if different Purchase Rights have identical exercise prices) shall be exercised.

6.     ELIGIBILITY.

(a)Purchase Rights may be granted only to Employees of the Company or, as the Board may designate as provided in
Section 3(b), to Employees of a Related Corporation. Except as provided in Section 6(b), an Employee shall not be eligible to be granted Purchase Rights under the Plan unless, on the
Offering Date, such Employee has been in the employ of the Company or the Related Corporation, as the case may be, for such continuous period preceding such Offering Date as the Board may require, but
in no event shall the required period of continuous employment be greater than two (2) years. In addition, the Board may provide that no Employee shall be eligible to be granted Purchase Rights
under the Plan unless, on the Offering Date, such Employee's customary employment with the Company or the Related Corporation is more than twenty (20) hours per week and more than five
(5) months per calendar year.

(b)The Board may provide that each person who, during the course of an Offering, first becomes an Eligible Employee shall,
on a date or dates specified in the Offering which coincides with the day on which such person becomes an Eligible Employee or which occurs thereafter, receive a Purchase Right under that Offering,
which Purchase Right shall thereafter be deemed to be a part of that Offering. Such Purchase Right shall have the same characteristics as any Purchase Rights originally granted under that Offering, as
described herein, except that:



(c)No Employee shall be eligible for the grant of any Purchase Rights under the Plan if, immediately after any such Purchase
Rights are granted, such Employee owns stock possessing five percent (5%) or more of the total combined voting power or value of all classes of stock of the Company or of any Related Corporation. For
purposes of this Section 6(c), the rules of Section 424(d) of the Code shall apply in determining the stock ownership of any Employee, and stock which such Employee may purchase under
all outstanding Purchase Rights and options shall be treated as stock owned by such Employee.

(d)As specified by Section 423(b)(8) of the Code, an Eligible Employee may be granted Purchase Rights under the Plan
only if such Purchase Rights, together with any other rights granted under all Employee Stock Purchase Plans of the Company and any Related Corporations, do not permit such Eligible Employee's rights
to purchase stock of the Company or any Related Corporation to accrue at a rate which exceeds twenty five thousand dollars ($25,000) of Fair Market Value of such stock (determined at the time such
rights are granted, and which, with respect to the Plan, shall be determined as of their respective Offering Dates) for each calendar year in which such rights are outstanding at any time.

(e)Officers of the Company and any designated Related Corporation, if they are otherwise Eligible Employees, shall be
eligible to participate in Offerings under the Plan. Notwithstanding the foregoing, the Board may provide in an Offering that Employees who are highly compensated Employees within the meaning of
Section 423(b)(4)(D) of the Code shall not be eligible to participate.

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7.     PURCHASE RIGHTS; PURCHASE PRICE.

(a)On each Offering Date, each Eligible Employee, pursuant to an Offering made under the Plan, shall be granted a Purchase
Right to purchase up to that number of shares of Common Stock purchasable either with a percentage or with a maximum dollar amount, as designated by the Board, but in either case not exceeding ten
percent (10%), of such Employee's Earnings (as defined by the Board in each Offering) during the period that begins on the Offering Date (or such later date as the Board determines for a particular
Offering) and ends on the date stated in the Offering, which date shall be no later than the end of the Offering.

(b)The Board shall establish one (1) or more Purchase Dates during an Offering as of which Purchase Rights granted
under the Plan and pursuant to that Offering shall be exercised and purchases of shares of Common Stock shall be carried out in accordance with such Offering.

(c)In connection with each Offering made under the Plan, the Board may specify a maximum number of shares of Common Stock
that may be purchased by any Participant on any Purchase Date during such Offering. In connection with each Offering made under the Plan, the Board may specify a maximum aggregate number of shares of
Common Stock that may be purchased by all Participants pursuant to such Offering. In addition, in connection with each Offering that contains more than one Purchase Date, the Board may specify a
maximum aggregate number of shares of Common Stock that may be purchased by all Participants on any given Purchase Date under the Offering. If the aggregate purchase of shares of Common Stock issuable
upon exercise of Purchase Rights granted under the Offering would exceed any such maximum aggregate number, then, in the absence of any Board action otherwise, a pro rata allocation of the shares of
Common Stock available shall be made in as nearly a uniform manner as shall be practicable and equitable.

(d)The purchase price of shares of Common Stock acquired pursuant to Purchase Rights granted under the Plan shall be not
less than the lesser of:



8.     PARTICIPATION; WITHDRAWAL; TERMINATION.

(a)An Eligible Employee may become a Participant in the Plan pursuant to an Offering by delivering a participation agreement
to the Company within the time specified in the Offering, in such form as the Company may provide. Each such agreement shall authorize payroll deductions of up to the maximum percentage specified by
the Board of such Participant's Earnings (as defined in each Offering) during the Offering. The payroll deductions made for each Participant shall be credited to a bookkeeping account for such
Participant under the Plan and shall be deposited with the general funds of the Company. To the extent provided in the Offering, a Participant may reduce (including to zero) or increase such payroll
deductions. To the extent provided in the Offering, a Participant may begin such payroll deductions after the beginning of the Offering. A Participant may make additional payments into his or her
account only if specifically provided for in the Offering and only if the Participant has not already had the maximum permitted amount withheld during the Offering.

(b)At any time during an Offering, a Participant may terminate his or her payroll deductions under the Plan and withdraw
from the Offering by delivering to the Company a notice of withdrawal in such form as the Company may provide. Such withdrawal may be elected at any time prior to the end of the Offering, except as
provided in the Offering. Upon such withdrawal from the Offering by a Participant, the Company shall distribute to such Participant all of his or her accumulated payroll deductions (reduced to the
extent, if any, such deductions have been used to acquire shares of Common Stock for the Participant) under the Offering, without interest (unless otherwise specified in the Offering), and such
Participant's interest in that Offering shall be automatically terminated. A Participant's withdrawal from an Offering shall have no effect upon such Participant's eligibility to

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participate
in any other Offerings under the Plan, but such Participant shall be required to deliver a new participation agreement in order to participate in subsequent Offerings under the Plan.

(c)Purchase Rights granted pursuant to any Offering under the Plan shall terminate immediately upon a Participant ceasing to
be an Employee for any reason or for no reason (subject to any post-employment participation period required by law) or other lack of eligibility. The Company shall distribute to such
terminated or otherwise ineligible Employee all of his or her accumulated payroll deductions (reduced to the extent, if any, such deductions have been used to acquire shares of Common Stock for the
terminated or otherwise ineligible Employee) under the Offering, without interest (unless otherwise specified in the Offering).

(d)Purchase Rights granted under the Plan shall not be transferable by a Participant otherwise than by will or the laws of
descent and distribution, or by a beneficiary designation as provided in Section 13 and, during a Participant's lifetime, shall be exercisable only by such Participant.

9.     EXERCISE.

(a)On each Purchase Date during an Offering, each Participant's accumulated payroll deductions and other additional payments
specifically provided for in the Offering (without any increase for interest) shall be applied to the purchase of shares of Common Stock up to the maximum number of shares of Common Stock permitted
pursuant to the terms of the Plan and the applicable Offering, at the purchase price specified in the Offering. No fractional shares shall be issued upon the exercise of Purchase Rights granted under
the Plan unless specifically provided for in the Offering.

(b)If any amount of accumulated payroll deductions remains in a Participant's account after the purchase of shares of Common
Stock and such remaining amount is less than the amount required to purchase one share of Common Stock on the final Purchase Date of an Offering, then such remaining amount shall be held in each such
Participant's account for the purchase of shares of Common Stock under the next Offering under the Plan, unless such Participant withdraws from such next Offering, as provided in Section 8(b),
or is not eligible to participate in such Offering, as provided in Section 6, in which case such amount shall be distributed to the Participant after said final Purchase Date, without interest
(unless otherwise specified in the Offering). If any amount, of accumulated payroll deductions remains in a Participant's account after the purchase of shares of Common Stock and such remaining amount
is equal to the amount required to purchase one (1) or more whole shares of Common Stock on the final Purchase Date of the Offering, then such remaining amount shall be distributed in full to
the Participant at the end of the Offering without interest (unless otherwise specified in the Offering).

(c)No Purchase Rights granted under the Plan may be exercised to any extent unless the shares of Common Stock to be issued
upon such exercise under the Plan are covered by an effective registration statement pursuant to the Securities Act and the Plan is in material compliance with all applicable federal, state, foreign
and other securities and other laws applicable to the Plan. If on a Purchase Date during any Offering hereunder the shares of Common Stock are not so registered or the Plan is not in such compliance,
no Purchase Rights granted under the Plan or any Offering shall be exercised on such Purchase Date, and the Purchase Date shall be delayed until the shares of Common Stock are subject to such an
effective registration statement and the Plan is in such compliance, except that the Purchase Date shall not be delayed more than twelve (12) months and the Purchase Date shall in no event be
more than twenty-seven (27) months from the Offering Date. If, on the Purchase Date under any Offering hereunder, as delayed to the maximum extent permissible, the shares of Common Stock are
not registered and the Plan is not in such compliance, no Purchase Rights granted under the Plan or any Offering shall be exercised and all payroll deductions accumulated during the Offering (reduced
to the extent, if any, such deductions have been used to acquire shares of Common Stock) shall be distributed to the Participants, without interest (unless otherwise specified in the Offering).

10.   COVENANTS OF THE COMPANY.

(a)During the terms of the Purchase Rights granted under the Plan, the Company shall ensure that the amount of shares of
Common Stock required to satisfy such Purchase Rights are available.

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(b)The Company shall seek to obtain from each federal, state, foreign or other regulatory commission or agency having
jurisdiction over the Plan such authority as may be required to issue and sell shares of Common Stock upon exercise of the Purchase Rights granted under the Plan. If, after reasonable efforts, the
Company is unable to obtain from any such regulatory commission or agency the authority that counsel for the Company deems necessary for the lawful issuance and sale of shares of Common Stock under
the Plan, the Company shall be relieved from any liability for failure to issue and sell shares of Common Stock upon exercise of such Purchase Rights unless and until such authority is obtained.

11.   USE OF PROCEEDS FROM SHARES OF COMMON STOCK.Proceeds from the sale of shares of Common Stock pursuant to Purchase Rights
granted under the Plan shall constitute general funds of the Company.

12.   RIGHTS AS A STOCKHOLDER.A Participant shall not be deemed to be the holder of, or to have any of the rights of a holder
with respect to, shares of Common Stock subject to Purchase Rights granted under the Plan unless and until the Participant's shares of Common Stock acquired upon exercise of Purchase Rights granted
under the Plan are recorded in the books of the Company (or its transfer agent).

13.   DESIGNATION OF BENEFICIARY.

(a)A Participant may file a written designation of a beneficiary who is to receive any shares of Common Stock and/or
cash, if any, from the Participant's account under the Plan in the event of such Participant's death subsequent to the end of an Offering but prior to delivery to the Participant of such shares of
Common Stock or cash. In addition, a Participant may file a written designation of a beneficiary who is to receive any cash from the Participant's account under the Plan in the event of such
Participant's death during an Offering.

(b)The Participant may change such designation of beneficiary at any time by written notice. In the event of the death of a
Participant and in the absence of a beneficiary validly designated under the Plan who is living at the time of such Participant's death, the Company shall deliver such shares of Common Stock and/or
cash to the executor or administrator of the estate of the Participant, or if no such executor or administrator has been appointed (to the knowledge of the Company), the Company, in its sole
discretion, may deliver such shares of Common Stock and/or cash to the spouse or to any one or more dependents or relatives of the Participant, or if no spouse, dependent or relative is known to the
Company, then to such other person as the Company may designate.

14.   ADJUSTMENTS UPON CHANGES IN SECURITIES; CORPORATE TRANSACTIONS.

(a)If any change is made in the shares of Common Stock, subject to the Plan, or subject to any Purchase Right, without the
receipt of consideration by the Company (through merger, consolidation, reorganization, recapitalization, reincorporation, stock dividend, dividend in property other than cash, stock split,
liquidating dividend, combination of shares, exchange of shares, change in corporate structure or other transaction not involving the receipt of consideration by the Company), the Plan shall be
appropriately adjusted in the type(s), class(es) and maximum number of shares of Common Stock subject to the Plan pursuant to Section 4(a), and the outstanding Purchase Rights granted under the
Plan shall be appropriately adjusted in the type(s), class(es), number of shares and purchase limits of such outstanding Purchase Rights. The Board shall make such adjustments, and its determination
shall be final, binding and conclusive. (The conversion of any convertible securities of the Company shall not be treated as a "transaction not involving the receipt of consideration by the Company.")

(b)In the event of a Corporate Transaction, then: (i) any surviving or acquiring corporation may continue or assume
Purchase Rights outstanding under the Plan or may substitute similar rights (including a right to acquire the same consideration paid to stockholders in the Corporate Transaction) for those
outstanding under the Plan, or (ii) if any surviving or acquiring corporation does not assume such Purchase Rights or does not substitute similar rights for Purchase Rights outstanding under
the Plan, then the Participants' accumulated payroll deductions (exclusive of any accumulated interest that

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cannot
be applied toward the purchase of shares of Common Stock under the terms of the Offering) shall be used to purchase shares of Common Stock immediately prior to the Corporate Transaction under
the ongoing Offering, and the Participants' Purchase Rights under the ongoing Offering shall terminate immediately after such purchase.

15.   AMENDMENT OF THE PLAN.

(a)The Board at any time, and from time to time, may amend the Plan. However, except as provided in Section 14
relating to adjustments upon changes in securities and except as to amendments solely to benefit the administration of the Plan, to take account of a change in legislation or to obtain or maintain
favorable tax, exchange control or regulatory treatment for Participants or the Company or any Related Corporation, no amendment shall be effective unless approved by the stockholders of the Company
to the extent stockholder approval is necessary for the Plan to satisfy the requirements of Section 423 of the Code or other applicable laws or regulations.

(b)It is expressly contemplated that the Board may amend the Plan in any respect the Board deems necessary or advisable to
provide Employees with the maximum benefits provided or to be provided under the provisions of the Code and the regulations promulgated thereunder relating to Employee Stock Purchase Plans and/or to
bring the Plan and/or Purchase Rights granted under the Plan into compliance therewith.

(c)The rights and obligations under any Purchase Rights granted before amendment of the Plan shall not be impaired by any
amendment of the Plan except (i) with the consent of the person to whom such Purchase Rights were granted, (ii) as necessary to comply with any laws or governmental regulations, or
(iii) as necessary to ensure that the Plan and/or Purchase Rights granted under the Plan comply with the requirements of Section 423 of the Code.

16.   TERMINATION OR SUSPENSION OF THE PLAN.

(a)The Board in its discretion may suspend or terminate the Plan at any time. No Purchase Rights may be granted under the
Plan while the Plan is suspended or after it is terminated.

(b)Any benefits, privileges, entitlements and obligations under any Purchase Rights granted under the Plan while the Plan is
in effect shall not be impaired by suspension or termination of the Plan except (i) as expressly provided in the Plan or with the consent of the person to whom such Purchase Rights were
granted, (ii) as necessary to comply with any laws, regulations, or listing requirements, or (iii) as necessary to ensure that the Plan and/or Purchase Rights granted under the Plan
comply with the requirements of Section 423 of the Code.

17.   EFFECTIVE DATE OF PLAN.The Plan shall become effective as determined by the Board, but no Purchase Rights granted under
the Plan shall be exercised unless and until the Plan has been approved by the stockholders of the Company within twelve (12) months before or after the date the Plan is adopted by the Board.

18.   MISCELLANEOUS PROVISIONS.

(a)The Plan and Offering do not constitute an employment contract. Nothing in the Plan or in the Offering shall in any way
alter the at will nature of a Participant's employment or be deemed to create in any way whatsoever any obligation on the part of any Participant to continue in the employ of the Company or a Related
Corporation, or on the part of the Company or a Related Corporation to continue the employment of a Participant.

(b)The provisions of the Plan shall be governed by the laws of the State of Colorado without resort to that state's
conflicts of laws rules.

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