Document:

EXHIBIT
4.14

 

ALLOS
THERAPEUTICS, INC.

 

and

 

                       ,
AS WARRANT AGENT

 

FORM OF
COMMON STOCK

 

WARRANT
AGREEMENT

 

DATED AS
OF

 

 

ALLOS
THERAPEUTICS, INC.

FORM OF COMMON STOCK WARRANT AGREEMENT

 

COMMON STOCK WARRANT AGREEMENT, dated as of                     ,
between ALLOS THERAPEUTICS, INC., a
Delaware corporation (the “COMPANY”) and
                                ,
a [corporation] [national banking association] organized and existing under the
laws of
                                
and having a corporate trust office in
                                ,
as warrant agent (the “WARRANT AGENT”).

 

WHEREAS, the Company proposes to sell [if Warrants are sold
with other securities—[title of such other securities being offered] (the “OTHER
SECURITIES”) with] warrant certificates evidencing one or more warrants (the “WARRANTS”
or individually a “WARRANT”) representing the right to purchase Common Stock of
the Company, par value $0.01 per share (the “WARRANT SECURITIES”), such warrant
certificates and other warrant certificates issued pursuant to this Agreement
being herein called the “WARRANT CERTIFICATES”; and

 

WHEREAS, the Company desires the Warrant Agent to act on
behalf of the Company, and the Warrant Agent is willing so to act, in
connection with the issuance, registration, transfer, exchange, exercise and
replacement of the Warrant Certificates, and in this Agreement wishes to set
forth, among other things, the form and provisions of the Warrant Certificates
and the terms and conditions on which they may be issued, registered,
transferred, exchanged, exercised and replaced;

 

NOW THEREFORE, in consideration of the premises and of the mutual
agreements herein contained, the parties hereto agree as follows:

 

1

 

ARTICLE 1

 

ISSUANCE OF WARRANTS AND EXECUTION AND DELIVERY OF
WARRANT CERTIFICATES

 

1.1                               Issuance of Warrants. [If Warrants alone—Upon issuance, each
Warrant Certificate shall evidence one or more Warrants.] [If Other Securities
and Warrants—Warrants shall be [initially] issued in connection with the
issuance of the Other Securities [but shall be separately transferable on and
after(the “DETACHABLE DATE”)] [and shall not be separately transferable] and
each Warrant Certificate shall evidence one or more Warrants.] Each Warrant
evidenced thereby shall represent the right, subject to the provisions
contained herein and therein, to purchase one Warrant Security. [If Other
Securities and Warrants—Warrant Certificates shall be initially issued in units
with the Other Securities and each Warrant Certificate included in such a unit
shall evidence Warrants for each [$principal amount] [ shares] of Other
Securities included in such unit.]

 

1.2                               Execution and Delivery of Warrant
Certificates.
Each Warrant Certificate, whenever issued, shall be in registered form
substantially in the form set forth in Exhibit A hereto, shall be dated
the date of its countersignature by the Warrant Agent and may have such
letters, numbers, or other marks of identification or designation and such
legends or endorsements printed, lithographed or engraved thereon as the
officers of the Company executing the same may approve (execution thereof to be
conclusive evidence of such approval) and as are not inconsistent with the provisions
of this Agreement, or as may be required to comply with any law or with any rule or
regulation made pursuant thereto or with any rule or regulation of any
securities exchange on which the Warrants may be listed, or to conform to
usage. The Warrant Certificates shall be signed on behalf of the Company by any
of its present or future chief executive officers, presidents, senior vice
presidents, vice presidents, chief financial officers, chief legal officers,
treasurers, assistant treasurers, controllers, assistant controllers,
secretaries or assistant secretaries under its corporate seal reproduced
thereon. Such signatures may be manual or facsimile signatures of such
authorized officers and may be imprinted or otherwise reproduced on the Warrant
Certificates. The seal of the Company may be in the form of a facsimile thereof
and may be impressed, affixed, imprinted or otherwise reproduced on the Warrant
Certificates.

 

No Warrant Certificate shall be valid for any purpose,
and no Warrant evidenced thereby shall be exercisable, until such Warrant
Certificate has been countersigned by the manual signature of the Warrant
Agent. Such signature by the Warrant Agent upon any Warrant Certificate
executed by the Company shall be conclusive evidence that the Warrant Certificate
so countersigned has been duly issued hereunder.

 

In case any officer of the Company who shall have
signed any of the Warrant Certificates either manually or by facsimile
signature shall cease to be such officer before the Warrant Certificates so
signed shall have been countersigned and delivered by the Warrant Agent, such
Warrant Certificates may be countersigned and delivered notwithstanding that
the person who signed Warrant Certificates ceased to be such officer of the
Company; and any Warrant Certificate may be signed on behalf of the Company by
such persons as, at the actual date of the execution of such Warrant
Certificate, shall be the proper officers of the Company, although at the date
of the execution of this Agreement any such person was not such officer.

 

2

 

The term “holder” or “holder of a Warrant Certificate”
as used herein shall mean any person in whose name at the time any Warrant
Certificate shall be registered upon the books to be maintained by the Warrant
Agent for that purpose [If Other Securities and Warrants are not immediately
detachable—or upon the registration of the Other Securities prior to the
Detachable Date. Prior to the Detachable Date, the Company will, or will cause the
registrar of the Other Securities to, make available at all times to the
Warrant Agent such information as to holders of the Other Securities as may be
necessary to keep the Warrant Agent’s records up to date].

 

1.3                               Issuance of Warrant Certificates. Warrant Certificates evidencing the
right to purchase Warrant Securities may be executed by the Company and
delivered to the Warrant Agent upon the execution of this Warrant Agreement or
from time to time thereafter. The Warrant Agent shall, upon receipt of Warrant
Certificates duly executed on behalf of the Company, countersign such Warrant
Certificates and shall deliver such Warrant Certificates to or upon the order
of the Company.

 

ARTICLE 2

 

WARRANT PRICE, DURATION AND EXERCISE
OF WARRANTS

 

2.1                               Warrant Price. During the period specified in Section 2.2,
each Warrant shall, subject to the terms of this Warrant Agreement and the
applicable Warrant Certificate, entitle the holder thereof to initially
purchase the number of Warrant Securities specified in the applicable Warrant
Certificate at an initial exercise price of $per Warrant Security, subject to
adjustment upon the occurrence of certain events to an exercise price not less
than the par value of the Warrant Securities, as hereinafter provided. Such
purchase price per Warrant Security is referred to in this Agreement as the “WARRANT
PRICE.”

 

2.2                               Duration of Warrants. Each Warrant may be exercised in whole
or in part at any time, as specified herein, on or after [the date thereof]
[          ] and at or before
           p.m., [City]
time, on, or such later date as the Company may designate by notice to the
Warrant Agent and the holders of Warrant Certificates mailed to their addresses
as set forth in the record books of the Warrant Agent (the “EXPIRATION DATE”).
Each Warrant not exercised at or before
           p.m., [City]
time, on the Expiration Date shall become void, and all rights of the holder of
the Warrant Certificate evidencing such Warrant under this Agreement shall
cease.

 

2.3                               Exercise of Warrants.

 

(a)                                  During the period specified in Section 2.2,
the Warrants may be exercised to purchase a whole number of Warrant Securities
in registered form by providing certain information as set forth on the reverse
side of the Warrant Certificate and by paying in full, in lawful money of the
United States of America, [in cash or by certified check or official bank check
in New York Clearing House funds] [by bank wire transfer in immediately
available funds] the Warrant Price for each Warrant Security with respect to
which a Warrant is being exercised to the Warrant Agent at its corporate trust
office, provided that such exercise is subject to receipt within five business
days of such payment by the Warrant Agent of the Warrant Certificate with the
form of election to purchase Warrant Securities set forth on the reverse side
of the Warrant Certificate properly completed and duly executed. The date on
which payment in full of the Warrant Price is received by the Warrant Agent
shall, subject to receipt of the Warrant

 

3

 

Certificate as aforesaid,
be deemed to be the date on which the Warrant is exercised; provided, however,
that if, at the date of receipt of such Warrant Certificates and payment in
full of the Warrant Price, the transfer books for the Warrant Securities
purchasable upon the exercise of such Warrants shall be closed, no such receipt
of such Warrant Certificates and no such payment of such Warrant Price shall be
effective to constitute the person so designated to be named as the holder of
record of such Warrant Securities on such date, but shall be effective to
constitute such person as the holder of record of such Warrant Securities for
all purposes at the opening of business on the next succeeding day on which the
transfer books for the Warrant Securities purchasable upon the exercise of such
Warrants shall be opened, and the certificates for the Warrant Securities in
respect of which such Warrants are then exercised shall be issuable as of the
date on such next succeeding day on which the transfer books shall next be
opened, and until such date the Company shall be under no duty to deliver any
certificate for such Warrant Securities. The Warrant Agent shall deposit all
funds received by it in payment of the Warrant Price in an account of the
Company maintained with it and shall advise the Company by telephone at the end
of each day on which a payment for the exercise of Warrants is received of the
amount so deposited to its account. The Warrant Agent shall promptly confirm
such telephone advice to the Company in writing.

 

(b)                                  The Warrant Agent shall, from time to
time, as promptly as practicable, advise the Company of (i) the number of
Warrant Securities with respect to which Warrants were exercised, (ii) the
instructions of each holder of the Warrant Certificates evidencing such
Warrants with respect to delivery of the Warrant Securities to which such
holder is entitled upon such exercise, (iii) delivery of Warrant
Certificates evidencing the balance, if any, of the Warrants for the remaining
Warrant Securities after such exercise, and (iv) such other information as
the Company shall reasonably require.

 

(c)                                  As soon as practicable after the exercise
of any Warrant, the Company shall issue to or upon the order of the holder of
the Warrant Certificate evidencing such Warrant the Warrant Securities to which
such holder is entitled, in fully registered form, registered in such name or
names as may be directed by such holder. If fewer than all of the Warrants evidenced
by such Warrant Certificate are exercised, the Company shall execute, and an
authorized officer of the Warrant Agent shall manually countersign and deliver,
a new Warrant Certificate evidencing Warrants for the number of Warrant
Securities remaining unexercised.

 

(d)                                  The Company shall not be required to pay
any stamp or other tax or other governmental charge required to be paid in
connection with any transfer involved in the issue of the Warrant Securities,
and in the event that any such transfer is involved, the Company shall not be
required to issue or deliver any Warrant Security until such tax or other
charge shall have been paid or it has been established to the Company’s
satisfaction that no such tax or other charge is due.

 

(e)                                  Prior to the issuance of any Warrants
there shall have been reserved, and the Company shall at all times through the
Expiration Date keep reserved, out of its authorized but unissued Warrant
Securities, a number of shares sufficient to provide for the exercise of the
Warrants.

 

4

 

ARTICLE 3

 

OTHER PROVISIONS RELATING TO RIGHTS
OF HOLDERS OF WARRANT CERTIFICATES

 

3.1                               No Rights as Warrant
Securityholder Conferred by Warrants or Warrant Certificates. No Warrant Certificate or Warrant
evidenced thereby shall entitle the holder thereof to any of the rights of a
holder of Warrant Securities, including, without limitation, the right to
receive the payment of dividends or distributions, if any, on the Warrant
Securities or to exercise any voting rights, except to the extent expressly set
forth in this Agreement or the applicable Warrant Certificate.

 

3.2                               Lost, Stolen, Mutilated or
Destroyed Warrant Certificates. Upon receipt by the Warrant Agent of evidence
reasonably satisfactory to it and the Company of the ownership of and the loss,
theft, destruction or mutilation of any Warrant Certificate and/or indemnity
reasonably satisfactory to the Warrant Agent and the Company and, in the case
of mutilation, upon surrender of the mutilated Warrant Certificate to the
Warrant Agent for cancellation, then, in the absence of notice to the Company
or the Warrant Agent that such Warrant Certificate has been acquired by a bona
fide purchaser, the Company shall execute, and an authorized officer of the Warrant
Agent shall manually countersign and deliver, in exchange for or in lieu of the
lost, stolen, destroyed or mutilated Warrant Certificate, a new Warrant
Certificate of the same tenor and evidencing Warrants for a like number of
Warrant Securities. Upon the issuance of any new Warrant Certificate under this
Section 3.2, the Company may require the payment of a sum sufficient to
cover any tax or other governmental charge that may be imposed in relation
thereto and any other expenses (including the fees and expenses of the Warrant
Agent) in connection therewith. Every substitute Warrant Certificate executed
and delivered pursuant to this Section 3.2 in lieu of any lost, stolen or
destroyed Warrant Certificate shall represent an additional contractual obligation
of the Company, whether or not the lost, stolen or destroyed Warrant
Certificate shall be at any time enforceable by anyone, and shall be entitled
to the benefits of this Agreement equally and proportionately with any and all
other Warrant Certificates duly executed and delivered hereunder. The
provisions of this Section 3.2 are exclusive and shall preclude (to the
extent lawful) all other rights and remedies with respect to the replacement of
mutilated, lost, stolen or destroyed Warrant Certificates.

 

3.3                               Holder of Warrant Certificate May Enforce
Rights.
Notwithstanding any of the provisions of this Agreement, any holder of a
Warrant Certificate, without the consent of the Warrant Agent, the holder of
any Warrant Securities or the holder of any other Warrant Certificate, may, in
such holder’s own behalf and for such holder’s own benefit, enforce, and may
institute and maintain any suit, action or proceeding against the Company
suitable to enforce, or otherwise in respect of, such holder’s right to exercise
the Warrants evidenced by such holder’s Warrant Certificate in the manner
provided in such holder’s Warrant Certificate and in this Agreement.

 

3.4                               Adjustments.

 

(a)                                  In case the Company shall at any time
subdivide its outstanding shares of Common Stock into a greater number of
shares, the Warrant Price in effect immediately prior to

 

5

 

such subdivision shall be
proportionately reduced and the number of Warrant Securities purchasable under
the Warrants shall be proportionately increased. Conversely, in case the
outstanding shares of Common Stock of the Company shall be combined into a
smaller number of shares, the Warrant Price in effect immediately prior to such
combination shall be proportionately increased and the number of Warrant
Securities purchasable under the Warrants shall be proportionately decreased.

 

(b)                                 If at any time or from time to time the
holders of Common Stock (or any shares of stock or other securities at the time
receivable upon the exercise of the Warrants) shall have received or become
entitled to receive, without payment therefore,

 

(i)                                    Common Stock or any shares of stock or
other securities which are at any time directly or indirectly convertible into
or exchangeable for Common Stock, or any rights or options to subscribe for,
purchase or otherwise acquire any of the foregoing by way of dividend or other
distribution;

 

(ii)                                any cash paid or payable otherwise than
as a cash dividend paid or payable out of the Company’s current or retained
earnings;

 

(iii)                            any evidence of the Company’s
indebtedness or rights to subscribe for or purchase the Company’s indebtedness;
or

 

(iv)                              Common Stock or additional stock or other
securities or property (including cash) by way of spinoff, split-up, reclassification,
combination of shares or similar corporate rearrangement (other than shares of
Common Stock issued as a stock split or adjustments in respect of which shall
be covered by the terms of Section 3.4(a) above), then and in each
such case, the holder of each Warrant shall, upon the exercise of the Warrant,
be entitled to receive, in addition to the number of Warrant Securities
receivable thereupon, and without payment of any additional consideration
therefore, the amount of stock and other securities and property (including
cash and indebtedness (or rights to subscribe for or purchase indebtedness)
which such holder would hold on the date of such exercise had he been the
holder of record of such Warrant Securities as of the date on which holders of
Common Stock received or became entitled to receive such shares or all other
additional stock and other securities and property.

 

(c)                                  In case of (i) any reclassification,
capital reorganization, or change in the Common Stock of the Company (other
than as a result of a subdivision, combination, or stock dividend provided for
in Section 3.4(a) or Section 3.4(b) above), (ii) share
exchange, merger or similar transaction of the Company with or into another
person or entity (other than a share exchange, merger or similar transaction in
which the Company is the acquiring or surviving corporation and which does not
result in any change in the Common Stock other than the issuance of additional
shares of Common Stock) or (iii) the sale, exchange, lease, transfer or other
disposition of all or substantially all of the properties and assets of the
Company as an entirety (in any such case, a “REORGANIZATION EVENT”), then, as a
condition of such Reorganization Event, lawful provisions shall be made, and
duly executed documents evidencing the same from the Company or its successor
shall be delivered to the holders of the Warrants, so that the holders of the
Warrants shall have the right at any time prior to the expiration of the
Warrants to purchase, at a total price equal to that payable upon the exercise
of the Warrants, the

 

6

 

kind and amount of shares
of stock and other securities and property receivable in connection with such
Reorganization Event by a holder of the same number of Warrant Securities as
were purchasable by the holders of the Warrants immediately prior to such
Reorganization Event. In any such case appropriate provisions shall be made
with respect to the rights and interests of the holders of the Warrants so that
the provisions hereof shall thereafter be applicable with respect to any shares
of stock or other securities and property deliverable upon exercise the
Warrants, and appropriate adjustments shall be made to the Warrant Price
payable hereunder provided the aggregate purchase price shall remain the same.
In the case of any transaction described in clauses (ii) and (iii) above,
the Company shall thereupon be relieved of any further obligation hereunder or
under the Warrants, and the Company as the predecessor corporation may
thereupon or at any time thereafter be dissolved, wound up or liquidated. Such
successor or assuming entity thereupon may cause to be signed, and may issue
either in its own name or in the name of the Company, any or all of the Warrants
issuable hereunder which heretofore shall not have been signed by the Company,
and may execute and deliver securities in its own name, in fulfillment of its
obligations to deliver Warrant Securities upon exercise of the Warrants. All
the Warrants so issued shall in all respects have the same legal rank and
benefit under this Agreement as the Warrants theretofore or thereafter issued
in accordance with the terms of this Agreement as though all of such Warrants
had been issued at the date of the execution hereof. In any case of any such
Reorganization Event, such changes in phraseology and form (but not in
substance) may be made in the Warrants thereafter to be issued as may be
appropriate.

 

The Warrant Agent may receive a written opinion of
legal counsel as conclusive evidence that any such Reorganization Event
complies with the provisions of this Section 3.4.

 

(d)                                  The Company may, at its option, at any
time until the Expiration Date, reduce the then current Warrant Price to any
amount deemed appropriate by the Board of Directors of the Company for any
period not exceeding twenty consecutive days (as evidenced in a resolution
adopted by such Board of Directors), but only upon giving the notices required
by Section 3.5 at least ten days prior to taking such action.

 

(e)                                  Except as herein otherwise expressly
provided, no adjustment in the Warrant Price shall be made by reason of the
issuance of shares of Common Stock, or securities convertible into or
exchangeable for shares of Common Stock, or securities carrying the right to
purchase any of the foregoing or for any other reason whatsoever.

 

(f)                                    No fractional Warrant Securities shall be
issued upon the exercise of Warrants. If more than one Warrant shall be
exercised at one time by the same holder, the number of full Warrant Securities
which shall be issuable upon such exercise shall be computed on the basis of
the aggregate number of Warrant Securities purchased pursuant to the Warrants
so exercised. Instead of any fractional Warrant Security which would otherwise
be issuable upon exercise of any Warrant, the Company shall pay a cash
adjustment in respect of such fraction in an amount equal to the same fraction
of the last sales price (or bid price if there were no sales) per Warrant
Security, in either case as reported on the New York Stock Exchange Composite
Tape on the business day which next precedes the day of exercise or, if the
Warrant Securities are not then listed or admitted to trading on the New York
Stock Exchange, on the principal national securities exchange on which the
Warrant Securities are listed or admitted to trading or, if not listed or
admitted to trading on any national securities exchange, on the NASDAQ Stock
Market

 

7

 

system of the National Association
of Securities Dealers, Inc. Automated Quotations System (“NASDAQ”), or if
the Warrant Securities are not then listed or admitted to trading on any
national securities exchange or quoted on the NASDAQ Stock Market system of
NASDAQ, the average of the closing high bid and low asked prices in the
over-the-counter market, as reported by NASDAQ, or such other system then in
use, or if on any such date the Warrant Securities are not quoted by any such
organization, an amount equal to the same fraction of the average of the
closing bid and asked prices as furnished by any New York Stock Exchange firm
selected from time to time by the Company for that purpose at the close of
business on the business day which next precedes the day of exercise.

 

(g)                                 Whenever the Warrant Price then in effect
is adjusted as herein provided, the Company shall mail to each holder of the
Warrants at such holder’s address as it shall appear on the books of the
Company a statement setting forth the adjusted Warrant Price then and
thereafter effective under the provisions hereof, together with the facts, in
reasonable detail, upon which such adjustment is based.

 

3.5                               Notice to Warrantholders. In case the Company shall (a) effect
any dividend or distribution described in Section 3.4(b), (b) effect
any Reorganization Event, (c) make any distribution on or in respect of
the Common Stock in connection with the dissolution, liquidation or winding up
of the Company, or (d) reduce the then current Warrant Price pursuant to Section 3.4(d),
then the Company shall mail to each holder of Warrants at such holder’s address
as it shall appear on the books of the Warrant Agent, at least ten days prior
to the applicable date hereinafter specified, a notice stating (x) the
record date for such dividend or distribution, or, if a record is not to be
taken, the date as of which the holders of record of Common Stock that will be
entitled to such dividend or distribution are to be determined, (y) the
date on which such Reorganization Event, dissolution, liquidation or winding up
is expected to become effective, and the date as of which it is expected that
holders of Common Stock of record shall be entitled to exchange their shares of
Common Stock for securities or other property deliverable upon such Reorganization
Event, dissolution, liquidation or winding up, or (z) the first date on
which the then current Warrant Price shall be reduced pursuant to Section 3.4(d).
No failure to mail such notice nor any defect therein or in the mailing thereof
shall affect any such transaction or any adjustment in the Warrant Price
required by Section 3.4.

 

3.6                               [If The Warrants are Subject to
Acceleration by the Company, Insert—Acceleration of Warrants by the Company.

 

(a)                                  At any time on or after, the Company
shall have the right to accelerate any or all Warrants at any time by causing
them to expire at the close of business on the day next preceding a specified
date (the “ACCELERATION DATE”), if the Market Price (as hereinafter defined) of
the Common Stock equals or exceeds percent (%) of the then effective Warrant
Price on any twenty Trading Days (as hereinafter defined) within a period of
thirty consecutive Trading Days ending no more than five Trading Days prior to
the date on which the Company gives notice to the Warrant Agent of its election
to accelerate the Warrants.

 

(b)                                  “Market Price” for each Trading Day shall
be, if the Common Stock is listed or admitted for trading on the New York Stock
Exchange, the last reported sale price, regular way (or, if no such price is reported,
the average of the reported closing bid and asked

 

8

 

prices, regular way) of
Common Stock, in either case as reported on the New York Stock Exchange
Composite Tape or, if the Common Stock is not listed or admitted to trading on
the New York Stock Exchange, on the principal national securities exchange on
which the Common Stock is listed or admitted to trading or, if not listed or
admitted to trading on any national securities exchange, on the NASDAQ Stock
Market system of NASDAQ or, if not listed or admitted to trading on any
national securities exchange or quoted on the NASDAQ Stock Market system of
NASDAQ, the average of the closing high bid and low asked prices in the
over-the-counter market, as reported by NASDAQ, or such other system then in
use, or if on any such date the shares of Common Stock are not quoted by any
such organization, the average of the closing bid and asked prices as furnished
by any New York Stock Exchange firm selected from time to time by the Company
for that purpose. “Trading Day” shall be each Monday through Friday, other than
any day on which securities are not traded in the system or on the exchange
that is the principal market for the Common Stock, as determined by the Board
of Directors of the Company.

 

(c)                                  In the event of an acceleration of less
than all of the Warrants, the Warrant Agent shall select the Warrants to be
accelerated by lot, pro rata or in such other manner as it deems, in its
discretion, to be fair and appropriate.

 

(d)                                  Notice of an acceleration specifying the
Acceleration Date shall be sent by mail first class, postage prepaid, to each
registered holder of a Warrant Certificate representing a Warrant accelerated
at such holder’s address appearing on the books of the Warrant Agent not more
than sixty days nor less than thirty days before the Acceleration Date. Such
notice of an acceleration also shall be given no more than twenty days, and no
less than ten days, prior to the mailing of notice to registered holders of
Warrants pursuant to this Section 3.6, by publication at least once in a
newspaper of general circulation in the City of New York.

 

(e)                                  Any Warrant accelerated may be exercised
until [    ] p.m., [City] time, on
the business day next preceding the Acceleration Date. The Warrant Price shall
be payable as provided in Section 2.]

 

ARTICLE 4

 

EXCHANGE AND TRANSFER OF WARRANT
CERTIFICATES

 

4.1                               Exchange and Transfer of Warrant
Certificates. [If
Other Securities with Warrants which are immediately detachable—Upon] [If Other
Securities with Warrants which are not immediately detachable—Prior to the
Detachable Date, a Warrant Certificate may be exchanged or transferred only
together with the Other Security to which the Warrant Certificate was initially
attached, and only for the purpose of effecting or in conjunction with an
exchange or transfer of such Other Security. Prior to any Detachable Date, each
transfer of the Other Security shall operate also to transfer the related
Warrant Certificates. After the Detachable Date, upon] surrender at the
corporate trust office of the Warrant Agent, Warrant Certificates evidencing
Warrants may be exchanged for Warrant Certificates in other denominations
evidencing such Warrants or the transfer thereof may be registered in whole or
in part; provided that such other Warrant Certificates evidence Warrants for
the same aggregate number of Warrant Securities as the Warrant Certificates so
surrendered. The Warrant Agent shall keep, at

 

9

 

its corporate trust
office, books in which, subject to such reasonable regulations as it may
prescribe, it shall register Warrant Certificates and exchanges and transfers
of outstanding Warrant Certificates, upon surrender of the Warrant Certificates
to the Warrant Agent at its corporate trust office for exchange or registration
of transfer, properly endorsed or accompanied by appropriate instruments of
registration of transfer and written instructions for transfer, all in form
satisfactory to the Company and the Warrant Agent. No service charge shall be
made for any exchange or registration of transfer of Warrant Certificates, but
the Company may require payment of a sum sufficient to cover any stamp or other
tax or other governmental charge that may be imposed in connection with any
such exchange or registration of transfer. Whenever any Warrant Certificates
are so surrendered for exchange or registration of transfer, an authorized
officer of the Warrant Agent shall manually countersign and deliver to the
person or persons entitled thereto a Warrant Certificate or Warrant
Certificates duly authorized and executed by the Company, as so requested. The
Warrant Agent shall not be required to effect any exchange or registration of
transfer which will result in the issuance of a Warrant Certificate evidencing
a Warrant for a fraction of a Warrant Security or a number of Warrants for a
whole number of Warrant Securities and a fraction of a Warrant Security. All
Warrant Certificates issued upon any exchange or registration of transfer of
Warrant Certificates shall be the valid obligations of the Company, evidencing
the same obligations and entitled to the same benefits under this Agreement as
the Warrant Certificate surrendered for such exchange or registration of
transfer.

 

4.2                               Treatment of Holders of Warrant
Certificates. [If
Other Securities and Warrants are not immediately detachable—Prior to the
Detachable Date, the Company, the Warrant Agent and all other persons may treat
the owner of the Other Security as the owner of the Warrant Certificates
initially attached thereto for any purpose and as the person entitled to
exercise the rights represented by the Warrants evidenced by such Warrant
Certificates, any notice to the contrary notwithstanding. After the Detachable
Date and prior to due presentment of a Warrant Certificate for registration of
transfer, the] [T]he Company, the Warrant Agent and all other persons may treat
the registered holder of a Warrant Certificate as the absolute owner thereof
for any purpose and as the person entitled to exercise the rights represented
by the Warrants evidenced thereby, any notice to the contrary notwithstanding.

 

4.3                               Cancellation of Warrant
Certificates. Any
Warrant Certificate surrendered for exchange, registration of transfer or
exercise of the Warrants evidenced thereby shall, if surrendered to the
Company, be delivered to the Warrant Agent and all Warrant Certificates
surrendered or so delivered to the Warrant Agent shall be promptly canceled by
the Warrant Agent and shall not be reissued and, except as expressly permitted
by this Agreement, no Warrant Certificate shall be issued hereunder in exchange
therefor or in lieu thereof.

 

The Warrant Agent shall deliver to the Company from
time to time or otherwise dispose of canceled Warrant Certificates in a manner
satisfactory to the Company.

 

ARTICLE 5

 

CONCERNING THE WARRANT AGENT

 

5.1                               Warrant Agent. The Company hereby appoints as Warrant
Agent of the Company in respect of the Warrants and the Warrant Certificates upon
the terms and subject to

 

10

 

the conditions herein set
forth, and hereby accepts such appointment. The Warrant Agent shall have the
powers and authority granted to and conferred upon it in the Warrant
Certificates and hereby and such further powers and authority to act on behalf
of the Company as the Company may hereafter grant to or confer upon it. All of
the terms and provisions with respect to such powers and authority contained in
the Warrant Certificates are subject to and governed by the terms and
provisions hereof.

 

5.2                               Conditions
of Warrant Agent’s Obligations. The Warrant Agent accepts its obligations
herein set forth upon the terms and conditions hereof, including the following
to all of which the Company agrees and to all of which the rights hereunder of
the holders from time to time of the Warrant Certificates shall be subject:

 

(a)                                  Compensation and Indemnification.
The Company agrees promptly to pay the Warrant Agent the compensation to be
agreed upon with the Company for all services rendered by the Warrant Agent and
to reimburse the Warrant Agent for reasonable out-of-pocket expenses (including
reasonable counsel fees) incurred without negligence, bad faith or willful
misconduct by the Warrant Agent in connection with the services rendered
hereunder by the Warrant Agent. The Company also agrees to indemnify the
Warrant Agent for, and to hold it harmless against, any loss, liability or
expense incurred without negligence, bad faith or willful misconduct on the
part of the Warrant Agent, arising out of or in connection with its acting as
Warrant Agent hereunder, including the reasonable costs and expenses of
defending against any claim of such liability.

 

(b)                                  Agent for the Company. In acting
under this Warrant Agreement and in connection with the Warrant Certificates,
the Warrant Agent is acting solely as agent of the Company and does not assume
any obligations or relationship of agency or trust for or with any of the
holders of Warrant Certificates or beneficial owners of Warrants.

 

(c)                                  Counsel. The Warrant Agent may
consult with counsel satisfactory to it, which may include counsel for the
Company, and the written advice of such counsel shall be full and complete
authorization and protection in respect of any action taken, suffered or
omitted by it hereunder in good faith and in accordance with the advice of such
counsel.

 

(d)                                  Documents. The Warrant Agent shall
be protected and shall incur no liability for or in respect of any action taken
or omitted by it in reliance upon any Warrant Certificate, notice, direction,
consent, certificate, affidavit, statement or other paper or document
reasonably believed by it to be genuine and to have been presented or signed by
the proper parties.

 

(e)                                  Certain Transactions. The Warrant
Agent, and its officers, directors and employees, may become the owner of, or
acquire any interest in, Warrants, with the same rights that it or they would
have if it were not the Warrant Agent hereunder, and, to the extent permitted
by applicable law, it or they may engage or be interested in any financial or other
transaction with the Company and may act on, or as depositary, trustee or agent
for, any committee or body of holders of Warrant Securities or other
obligations of the Company as freely as if it were not the Warrant Agent
hereunder. Nothing in this Warrant Agreement shall be

 

11

 

deemed to prevent the
Warrant Agent from acting as trustee under any indenture to which the Company
is a party.

 

(f)                                    No Liability for Interest. Unless
otherwise agreed with the Company, the Warrant Agent shall have no liability
for interest on any monies at any time received by it pursuant to any of the
provisions of this Agreement or of the Warrant Certificates.

 

(g)                                 No Liability for Invalidity. The
Warrant Agent shall have no liability with respect to any invalidity of this
Agreement or any of the Warrant Certificates (except as to the Warrant Agent’s
countersignature thereon).

 

(h)                                 No Responsibility for Representations.
The Warrant Agent shall not be responsible for any of the recitals or
representations herein or in the Warrant Certificates (except as to the Warrant
Agent’s countersignature thereon), all of which are made solely by the Company.

 

(i)                                    No Implied Obligations. The
Warrant Agent shall be obligated to perform only such duties as are herein and
in the Warrant Certificates specifically set forth and no implied duties or
obligations shall be read into this Agreement or the Warrant Certificates
against the Warrant Agent. The Warrant Agent shall not be under any obligation
to take any action hereunder which may tend to involve it in any expense or
liability, the payment of which within a reasonable time is not, in its
reasonable opinion, assured to it. The Warrant Agent shall not be accountable
or under any duty or responsibility for the use by the Company of any of the
Warrant Certificates authenticated by the Warrant Agent and delivered by it to
the Company pursuant to this Agreement or for the application by the Company of
the proceeds of the Warrant Certificates. The Warrant Agent shall have no duty
or responsibility in case of any default by the Company in the performance of
its covenants or agreements contained herein or in the Warrant Certificates or
in the case of the receipt of any written demand from a holder of a Warrant
Certificate with respect to such default, including, without limiting the
generality of the foregoing, any duty or responsibility to initiate or attempt
to initiate any proceedings at law or otherwise or, except as provided in Section 6.2
hereof, to make any demand upon the Company.

 

5.3                               Resignation
and Appointment Of Successor.

 

(a)                                  The
Company agrees, for the benefit of the holders from time to time of the Warrant
Certificates, that there shall at all times be a Warrant Agent hereunder until
all the Warrants have been exercised or are no longer exercisable.

 

(b)                                  The
Warrant Agent may at any time resign as agent by giving written notice to the
Company of such intention on its part, specifying the date on which its desired
resignation shall become effective; provided that such date shall not be less
than three months after the date on which such notice is given unless the
Company otherwise agrees. The Warrant Agent hereunder may be removed at any
time by the filing with it of an instrument in writing signed by or on behalf
of the Company and specifying such removal and the intended date when it shall
become effective. Such resignation or removal shall take effect upon the
appointment by the Company, as hereinafter provided, of a successor Warrant Agent
(which shall be a bank or trust company authorized under the laws of the
jurisdiction of its organization to exercise

 

12

 

corporate trust powers)
and the acceptance of such appointment by such successor Warrant Agent. The
obligation of the Company under Section 5.2(a) shall continue to the
extent set forth therein notwithstanding the resignation or removal of the
Warrant Agent.

 

(c)                                  In
case at any time the Warrant Agent shall resign, or shall be removed, or shall
become incapable of acting, or shall be adjudged a bankrupt or insolvent, or
shall commence a voluntary case under the Federal bankruptcy laws, as now or
hereafter constituted, or under any other applicable Federal or state
bankruptcy, insolvency or similar law or shall consent to the appointment of or
taking possession by a receiver, custodian, liquidator, assignee, trustee,
sequestrator (or other similar official) of the Warrant Agent or its property
or affairs, or shall make an assignment for the benefit of creditors, or shall
admit in writing its inability to pay its debts generally as they become due,
or shall take corporate action in furtherance of any such action, or a decree
or order for relief by a court having jurisdiction in the premises shall have
been entered in respect of the Warrant Agent in an involuntary case under the
Federal bankruptcy laws, as now or hereafter constituted, or any other
applicable Federal or state bankruptcy, insolvency or similar law, or a decree
or order by a court having jurisdiction in the premises shall have been entered
for the appointment of a receiver, custodian, liquidator, assignee, trustee,
sequestrator (or similar official) of the Warrant Agent or of its property or
affairs, or any public officer shall take charge or control of the Warrant
Agent or of its property or affairs for the purpose of rehabilitation,
conservation, winding up or liquidation, a successor Warrant Agent, qualified
as aforesaid, shall be appointed by the Company by an instrument in writing,
filed with the successor Warrant Agent. Upon the appointment as aforesaid of a
successor Warrant Agent and acceptance by the successor Warrant Agent of such
appointment, the Warrant Agent shall cease to be Warrant Agent hereunder.

 

(d)                                  Any
successor Warrant Agent appointed hereunder shall execute, acknowledge and
deliver to its predecessor and to the Company an instrument accepting such
appointment hereunder, and thereupon such successor Warrant Agent, without any
further act, deed or conveyance, shall become vested with all the authority,
rights, powers, trusts, immunities, duties and obligations of such predecessor
with like effect as if originally named as Warrant Agent hereunder, and such
predecessor, upon payment of its charges and disbursements then unpaid, shall
thereupon become obligated to transfer, deliver and pay over, and such
successor Warrant Agent shall be entitled to receive, all monies, securities
and other property on deposit with or held by such predecessor, as Warrant
Agent hereunder.

 

(e)                                  Any
corporation into which the Warrant Agent hereunder may be merged or converted
or any corporation with which the Warrant Agent may be consolidated, or any
corporation resulting from any merger, conversion or consolidation to which the
Warrant Agent shall be a party, or any corporation to which the Warrant Agent
shall sell or otherwise transfer all or substantially all the assets and
business of the Warrant Agent, provided that it shall be qualified as
aforesaid, shall be the successor Warrant Agent under this Agreement without
the execution or filing of any paper or any further act on the part of any of
the parties hereto.

 

13

 

ARTICLE
6

 

MISCELLANEOUS

 

6.1                               Amendment.
This Agreement may be amended by the parties hereto, without the consent of the
holder of any Warrant Certificate, for the purpose of curing any ambiguity, or
of curing, correcting or supplementing any defective provision contained
herein, or making any other provisions with respect to matters or questions
arising under this Agreement as the Company and the Warrant Agent may deem
necessary or desirable; provided that such action shall not materially
adversely affect the interests of the holders of the Warrant Certificates.

 

6.2                               Notices
and Demands to the Company and Warrant Agent. If the Warrant Agent shall
receive any notice or demand addressed to the Company by the holder of a
Warrant Certificate pursuant to the provisions of the Warrant Certificates, the
Warrant Agent shall promptly forward such notice or demand to the Company.

 

6.3                               Addresses.
Any communication from the Company to the Warrant Agent with respect to this
Agreement shall be addressed to, Attention: and any communication from the
Warrant Agent to the Company with respect to this Agreement shall be addressed
to Allos Therapeutics, Inc., 11080 CirclePoint Road, Suite 200,
Westminster, Colorado 80020, Attention: 
Corporate Secretary (or such other address as shall be specified in
writing by the Warrant Agent or by the Company).

 

6.4                               Governing
Law. This Agreement and each Warrant Certificate issued hereunder shall be
governed by and construed in accordance with the laws of the State of New York.

 

6.5                               Delivery
of Prospectus. The Company shall furnish to the Warrant Agent sufficient copies
of a prospectus meeting the requirements of the Securities Act of 1933, as
amended, relating to the Warrant Securities deliverable upon exercise of the
Warrants (the “PROSPECTUS”), and the Warrant Agent agrees that upon the
exercise of any Warrant, the Warrant Agent will deliver to the holder of the
Warrant Certificate evidencing such Warrant, prior to or concurrently with the
delivery of the Warrant Securities issued upon such exercise, a Prospectus.

 

The Warrant Agent shall not, by reason of any such
delivery, assume any responsibility for the accuracy or adequacy of such
Prospectus.

 

6.6                               Obtaining
of Governmental Approvals. The Company will from time to time take all
action which may be necessary to obtain and keep effective any and all permits,
consents and approvals of governmental agencies and authorities and securities
act filings under United States Federal and state laws (including without
limitation a registration statement in respect of the Warrants and Warrant
Securities under the Securities Act of 1933, as amended), which may be or
become requisite in connection with the issuance, sale, transfer, and delivery
of the Warrant Securities issued upon exercise of the Warrants, the issuance,
sale, transfer and delivery of the Warrants or upon the expiration of the
period during which the Warrants are exercisable.

 

14

 

6.7                               Persons
Having Rights Under Warrant Agreement. Nothing in this Agreement shall give
to any person other than the Company, the Warrant Agent and the holders of the
Warrant Certificates any right, remedy or claim under or by reason of this
Agreement.

 

6.8                               Headings.
The descriptive headings of the several Articles and Sections of this Agreement
are inserted for convenience only and shall not control or affect the meaning
or construction of any of the provisions hereof.

 

6.9                               Counterparts.
This Agreement may be executed in any number of counterparts, each of which as
so executed shall be deemed to be an original, but such counterparts shall
together constitute but one and the same instrument.

 

6.10                        Inspection
of Agreement. A copy of this Agreement shall be available at all reasonable
times at the principal corporate trust office of the Warrant Agent for
inspection by the holder of any Warrant Certificate. The Warrant Agent may
require such holder to submit his Warrant Certificate for inspection by it.

 

IN WITNESS WHEREOF,
the parties hereto have caused this Agreement to be duly executed, all as of
the day and year first above written.

 

	
  

  	
   

  	
   

  	
   

  	
   

  	
  ALLOS THERAPEUTICS, INC.

  
	
   

  	
   

  	
   

  	
   

  	
   

  	
   

  
	
   

  	
   

  	
  By:

  	
   

  
	
   

  	
   

  	
   

  	
   

  
	
   

  	
   

  	
  Its:

  	
   

  
	
  Attest:

  	
   

  	
   

  	
   

  
	
   

  	
   

  	
   

  
	
   

  	
   

  	
   

  
	
   

  	
   

  	
   

  
	
   

  	
   

  	
   

  
	
   

  	
   

  	
   

  
	
   

  	
   

  	
   

  
	
   

  	
   

  	
   

  
	
   

  	
   

  	
  WARRANT
  AGENT

  
	
   

  	
   

  	
   

  
	
   

  	
   

  	
  By:

  	
   

  
	
   

  	
   

  	
   

  	
   

  
	
   

  	
   

  	
  Its:

  	
   

  
	
   

  	
   

  	
   

  	
   

  
	
  Attest:

  	
   

  	
   

  	
   

  
	
   

  	
   

  	
   

  
	
   

  	
   

  	
   

  
	
   

  	
   

  	
   

  

 

[SIGNATURE PAGE TO COMMON
STOCK WARRANT AGREEMENT]

 

15

 

EXHIBIT A

 

FORM OF WARRANT CERTIFICATE

[FACE OF WARRANT CERTIFICATE]

 

	
  [[Form if Warrants
  are attached to Other Securities and are not immediately detachable.]

  	
   

  	
  [Prior to
            , this Warrant
  Certificate cannot be transferred or exchanged unless attached to a [Title of
  Other Securities].]

  
	
  [Form of Legend if
  Warrants are not immediately exercisable.]

  	
   

  	
  [Prior to
            , Warrants
  evidenced by this Warrant Certificate cannot be exercised.]

  

 

EXERCISABLE ONLY IF COUNTERSIGNED
BY THE WARRANT AGENT AS PROVIDED HEREIN

 

VOID AFTER
           P.M., [CITY]
TIME, ON    ,

 

ALLOS
THERAPEUTICS, INC.

 

WARRANT
CERTIFICATE REPRESENTING

 

WARRANTS
TO PURCHASE

 

COMMON
STOCK, PAR VALUE $0.01 PER SHARE

 

	
  No.

  	
   

  	
  Warrants

  

 

This certifies that
                      
or registered assigns is the registered owner of the above indicated number of
Warrants, each Warrant entitling such owner [if Warrants are attached to Other
Securities and are not immediately detachable—, subject to the registered owner
qualifying as a “Holder” of this Warrant Certificate, as hereinafter defined),]
to purchase, at any time [after
           p.m., [City]
time, on and] on or before
           p.m., [City]
time, on
                        ,
shares of Common Stock, par value $0.01 per share (the “WARRANT SECURITIES”),
of Allos Therapeutics, Inc. (the “COMPANY”) on the following basis: during
the period from           ,
through and including
          , the exercise
price per Warrant Security will be
$          , subject to
adjustment as provided in the Warrant Agreement (as hereinafter defined) (the “WARRANT
PRICE”). The Holder may exercise the Warrants evidenced hereby by providing
certain information set forth on the back hereof and by paying in full, in
lawful money of the United States of America, [in cash or by certified check or
official bank check in New York Clearing House funds][by bank wire transfer in
immediately available funds], the Warrant Price for each Warrant Security with
respect to which this Warrant is exercised to the Warrant Agent (as hereinafter
defined) and by surrendering this Warrant Certificate, with the purchase form
on the back hereof duly executed, at the corporate trust office of [name of
Warrant Agent], or its successor as warrant agent (the “WARRANT AGENT”), which
is, on the date hereof, at the address specified on the reverse hereof, and
upon compliance with and subject to the conditions set forth herein and in the
Warrant Agreement (as hereinafter defined).

 

1

 

The term “HOLDER”
as used herein shall mean [if Warrants are attached to Other Securities and are
not immediately detachable—prior
to          ,
          (the “DETACHABLE
DATE”), the registered owner of the Company’s [title of Other Securities] to
which this Warrant Certificate was initially attached, and after such
Detachable Date,] the person in whose name at the time this Warrant Certificate
shall be registered upon the books to be maintained by the Warrant Agent for
that purpose pursuant to Section 4 of the Warrant Agreement.

 

The Warrants evidenced by this Warrant Certificate may
be exercised to purchase a whole number of Warrant Securities in registered
form. Upon any exercise of fewer than all of the Warrants evidenced by this
Warrant Certificate, there shall be issued to the Holder hereof a new Warrant
Certificate evidencing Warrants for the number of Warrant Securities remaining
unexercised.

 

This Warrant Certificate is issued under and in
accordance with the Warrant Agreement dated as of, (the “WARRANT AGREEMENT”),
between the Company and the Warrant Agent and is subject to the terms and
provisions contained in the Warrant Agreement, to all of which terms and
provisions the Holder of this Warrant Certificate consents by acceptance
hereof. Copies of the Warrant Agreement are on file at the above-mentioned
office of the Warrant Agent.

 

[If Warrants are attached to Other Securities and are
not immediately detachable—Prior to the Detachable Date, this Warrant
Certificate may be exchanged or transferred only together with the [Title of
Other Securities] (the “OTHER SECURITIES”) to which this Warrant Certificate
was initially attached, and only for the purpose of effecting or in conjunction
with, an exchange or transfer of such Other Security. Additionally, on or prior
to the Detachable Date, each transfer of such Other Security on the register of
the Other Securities shall operate also to transfer this Warrant Certificate.
After such date, transfer of this] [If Warrants are attached to Other
Securities and are immediately detachable—Transfer of this]Warrant Certificate
may be registered when this Warrant Certificate is surrendered at the corporate
trust office of the Warrant Agent by the registered owner or such owner’s
assigns, in the manner and subject to the limitations provided in the Warrant
Agreement.

 

[If Other Securities with Warrants which are not
immediately detachable—Except as provided in the immediately preceding
paragraph, after] [If Other Securities with Warrants which are immediately
detachable or Warrants alone—After] countersignature by the Warrant Agent and
prior to the expiration of this Warrant Certificate, this Warrant Certificate
may be exchanged at the corporate trust office of the Warrant Agent for Warrant
Certificates representing Warrants for the same aggregate number of Warrant
Securities.

 

This Warrant Certificate shall not entitle the Holder
hereof to any of the rights of a holder of the Warrant Securities, including,
without limitation, the right to receive payments of dividends or
distributions, if any, on the Warrant Securities (except to the extent set
forth in the Warrant Agreement) or to exercise any voting rights.

 

Reference is hereby made to the further provisions of
this Warrant Certificate set forth on the reverse hereof, which further
provisions shall for all purposes have the same effect as if set forth at this
place.

 

2

 

This Warrant Certificate shall be governed by and construed
in accordance with the laws of the State of New York.

 

This Warrant Certificate shall not be valid or
obligatory for any purpose until countersigned by the Warrant Agent.

 

IN WITNESS WHEREOF, the Company
has caused this Warrant to be executed in its name and on its behalf by the
facsimile signatures of its duly authorized officers.

 

	
  Dated:

  	
   

  	
   

  	
  ALLOS THERAPEUTICS, INC.

  
	
   

  	
   

  	
   

  	
   

  
	
   

  	
   

  	
  By:

  	
   

  
	
   

  	
   

  	
   

  	
   

  
	
   

  	
   

  	
  Its:

  	
   

  
	
  Attest:

  	
   

  	
   

  	
   

  
	
   

  	
   

  	
   

  
	
   

  	
   

  	
   

  
	
   

  	
   

  	
   

  
	
   

  	
   

  	
   

  
	
   

  	
   

  	
   

  
	
   

  	
   

  	
   

  
	
   

  	
   

  	
  Countersigned:

  
	
   

  	
   

  	
   

  
	
   

  	
   

  	
   

  
	
   

  	
   

  	
  As Warrant Agent

  
	
   

  	
   

  	
   

  
	
   

  	
   

  	
  By:

  	
   

  
	
   

  	
   

  	
   

  	
  Authorized Signature

  

 

3

 

[REVERSE
OF WARRANT CERTIFICATE]

 

(Instructions for
Exercise of Warrant)

 

To exercise any Warrants evidenced hereby for Warrant
Securities (as hereinafter defined), the Holder must pay, in lawful money of
the United States of America, [in cash or by certified check or official bank
check in New York Clearing House funds] [by bank wire transfer in immediately
available funds], the Warrant Price in full for Warrants exercised, to [Warrant
Agent] [address of Warrant Agent],
Attn:           , which
payment must specify the name of the Holder and the number of Warrants
exercised by such Holder. In addition, the Holder must complete the information
required below and present this Warrant Certificate in person or by mail
(certified or registered mail is recommended) to the Warrant Agent at the
appropriate address set forth above. This Warrant Certificate, completed and
duly executed, must be received by the Warrant Agent within five business days
of the payment.

 

(To be executed upon exercise of Warrants)

 

The undersigned hereby irrevocably elects to exercise
           Warrants,
evidenced by this Warrant Certificate, to purchase
           shares of the Common
Stock, par value $0.01 per share (the “WARRANT SECURITIES”), of Allos
Therapeutics, Inc. and represents that he has tendered payment for such
Warrant Securities, in lawful money of the United States of America, [in cash
or by certified check or official bank check in New York Clearing House funds]
[by bank wire transfer in immediately available funds], to the order of Allos
Therapeutics, Inc., c/o [insert name and address of Warrant Agent], in the
amount of $           in
accordance with the terms hereof. The undersigned requests that said Warrant
Securities be in fully registered form in the authorized denominations,
registered in such names and delivered all as specified in accordance with the
instructions set forth below.

 

If the number of Warrants exercised is less than all
of the Warrants evidenced hereby, the undersigned requests that a new Warrant
Certificate evidencing the Warrants for the number of Warrant Securities
remaining unexercised be issued and delivered to the undersigned unless
otherwise specified in the instructions below.

 

	
  Dated:

  	
   

  	
   

  	
  Name:

  	
   

  
	
   

  	
   

  	
   

  	
  (Please Print)

  
	
   

  	
   

  	
   

  
	
   

  	
   

  	
   

  
	
  Address:

  	
   

  	
   

  
	
   

  	
   

  	
   

  
	
   

  	
   

  	
   

  
	
   

  	
   

  	
   

  
	
   

  	
   

  	
   

  
	
   

  	
   

  	
   

  
	
   

  	
   

  	
   

  
	
   

  	
   

  	
   

  
	
  (Insert Social
  Security or Other Identifying Number of Holder)

  	
   

  	
   

  

 

4

 

	
  Signature Guaranteed:

  	
   

  	
   

  
	
   

   

  	
   

  
	
  Signature 

   

  	
   

  
	
  (Signature must conform in all respects to name of
  holder as specified on the face of this Warrant Certificate and must bear a
  signature guarantee by a bank, trust company or member broker of the New
  York, Midwest or Pacific Stock Exchange).

   

  
	
  This Warrant may be exercised at the following
  addresses:

   

  
	
  By hand at

  	
   

  	
   

  
	
   

  	
   

  
	
   

  	
   

  
	
   

  	
   

  
	
   

  	
   

  
	
   

   

  	
   

  	
   

  
	
  By mail at:

  	
   

  	
   

  
	
   

  	
   

  	
   

  
	
   

  	
   

  
	
   

  	
   

  	
   

  
	
   

  	
   

  
						

 

[Instructions as to form
and delivery of Warrant Securities and, if applicable, Warrant Certificates
evidencing Warrants for the number of Warrant Securities remaining
unexercised—complete as appropriate.]

 

5

 

ASSIGNMENT

 

[Form of assignment
to be executed if Warrant Holder desires to transfer Warrant)

 

FOR VALUE RECEIVED,
                                        
hereby sells, assigns and transfers unto:

 

 

	
  

  	
   

  	
   

  
	
   

  	
   

  	
   

  
	
   

  	
   

  	
   

  
	
   

  	
   

  	
   

  
	
   

  	
   

  	
   

  
	
  (Please print
  name and address including zip code)

  	
   

  	
  Please insert Social Security or other identifying
  number

  

 

the right represented by
the within Warrant to purchase    shares
of [Title of Warrant Securities] of Allos Therapeutics, Inc. to which the
within Warrant relates and appoints   
attorney to transfer such right on the books of the Warrant Agent with
full power of substitution in the premises.

 

	
  Dated:

  	
   

  	
   

  	
   

  	
   

  
	
   

  	
   

  	
   

  	
  Signature

  

 

 

(Signature must conform
in all respects to name of holder as specified on the face of the Warrant)

 

Signature Guaranteed

 

	
  

   

  	
   

  	
   

  

 

6EXHIBIT 4.15

 

ALLOS
THERAPEUTICS, INC.

 

and

 

                       ,
AS WARRANT AGENT

 

FORM OF
PREFERRED STOCK

WARRANT AGREEMENT

 

DATED AS
OF

 

ALLOS
THERAPEUTICS, INC.

FORM OF PREFERRED STOCK WARRANT
AGREEMENT

 

PREFERRED STOCK WARRANT AGREEMENT, dated as of
                
between ALLOS THERAPEUTICS, INC., a Delaware corporation (the “COMPANY”) and
                     ,
a [corporation] [national banking association] organized and existing under the
laws of                   
and  having a corporate trust office in
                       ,
as warrant agent (the “WARRANT AGENT”).

 

WHEREAS, the Company proposes to sell [if Warrants are
sold with other securities — [title of such other securities being offered]
(the “OTHER SECURITIES”) with] warrant certificates evidencing one or more
warrants (the “WARRANTS” or, individually, a “WARRANT”) representing the right
to purchase [title of Preferred Stock purchasable through exercise of Warrants]
(the “WARRANT SECURITIES”), such warrant certificates and other warrant
certificates issued pursuant to this Agreement being herein called the “WARRANT
CERTIFICATES”; and

 

WHEREAS, the Company desires the Warrant Agent to act
on behalf of the Company, and the Warrant Agent is willing so to act, in
connection with the issuance, registration, transfer, exchange, exercise and
replacement of the Warrant Certificates, and in this Agreement wishes to set
forth, among other things, the form and provisions of the Warrant Certificates
and the terms and conditions on which they may be issued, registered,
transferred, exchanged, exercised and replaced;

 

NOW THEREFORE, in consideration of the premises and of
the mutual agreements herein contained, the parties hereto agree as follows:

 

1

 

ARTICLE 1

 

ISSUANCE OF WARRANTS AND EXECUTION AND DELIVERY OF
WARRANT CERTIFICATES

 

1.1                               Issuance
of Warrants. [If Warrants alone—Upon issuance, each Warrant Certificate
shall evidence one or more Warrants.] [If Other Securities and
Warrants—Warrants shall be [initially] issued in connection with the issuance
of the Other Securities [but shall be separately transferable on and after
                
(the “DETACHABLE DATE”)] [and shall not be separately transferable] and each
Warrant Certificate shall evidence one or more Warrants.] Each Warrant
evidenced thereby shall represent the right, subject to the provisions
contained herein and therein, to purchase one Warrant Security. [If Other
Securities and Warrants—Warrant Certificates shall be initially issued in units
with the Other Securities and each Warrant Certificate included in such a unit
shall evidence
             
Warrants for each [$           
principal amount]
[            shares] of
Other Securities included in such unit.]

 

1.2                               Execution
and Delivery of Warrant Certificates. Each Warrant Certificate, whenever
issued, shall be in registered form substantially in the form set forth in Exhibit A
hereto, shall be dated the date of its countersignature by the Warrant Agent
and may have such letters, numbers, or other marks of identification or
designation and such legends or endorsements printed, lithographed or engraved
thereon as the officers of the Company executing the same may approve
(execution thereof to be conclusive evidence of such approval) and as are not
inconsistent with the provisions of this Agreement, or as may be required to
comply with any law or with any rule or regulation made pursuant thereto
or with any rule or regulation of any securities exchange on which the
Warrants may be listed, or to conform to usage. The Warrant Certificates shall
be signed on behalf of the Company by any of its present or future chief
executive officers, presidents, senior vice presidents, vice presidents, chief
financial officers, chief legal officers, treasurers, assistant treasurers,
controllers, assistant controllers, secretaries or assistant secretaries under
its corporate seal reproduced thereon. Such signatures may be manual or
facsimile signatures of such authorized officers and may be imprinted or otherwise
reproduced on the Warrant Certificates. The seal of the Company may be in the
form of a facsimile thereof and may be impressed, affixed, imprinted or
otherwise reproduced on the Warrant Certificates.

 

No Warrant Certificate shall be valid for any purpose,
and no Warrant evidenced thereby shall be exercisable, until such Warrant
Certificate has been countersigned by the manual signature of the Warrant
Agent. Such signature by the Warrant Agent upon any Warrant Certificate
executed by the Company shall be conclusive evidence that the Warrant
Certificate so countersigned has been duly issued hereunder.

 

In case any officer of the Company who shall have
signed any of the Warrant Certificates either manually or by facsimile
signature shall cease to be such officer before the Warrant Certificates so
signed shall have been countersigned and delivered by the Warrant Agent, such
Warrant Certificates may be countersigned and delivered notwithstanding that
the person who signed Warrant Certificates ceased to be such officer of the
Company; and any Warrant Certificate may be signed on behalf of the Company by
such persons as, at the actual date of the

 

2

 

execution of such Warrant Certificate, shall be the
proper officers of the Company, although at the date of the execution of this
Agreement any such person was not such officer.

 

The term “holder” or “holder of a Warrant Certificate”
as used herein shall mean any person in whose name at the time any Warrant
Certificate shall be registered upon the books to be maintained by the Warrant
Agent for that purpose [If Other Securities and Warrants are not immediately
detachable—or upon the registration of the Other Securities prior to the
Detachable Date. Prior to the Detachable Date, the Company will, or will cause
the registrar of the Other Securities to, make available at all times to the
Warrant Agent such information as to holders of the Other Securities as may be
necessary to keep the Warrant Agent’s records up to date].

 

1.3                               Issuance
of Warrant Certificates. Warrant Certificates evidencing the right to
purchase Warrant Securities may be executed by the Company and delivered to the
Warrant Agent upon the execution of this Warrant Agreement or from time to time
thereafter. The Warrant Agent shall, upon receipt of Warrant Certificates duly
executed on behalf of the Company, countersign such Warrant Certificates and
shall deliver such Warrant Certificates to or upon the order of the Company.

 

ARTICLE 2

 

WARRANT PRICE, DURATION AND EXERCISE OF WARRANTS

 

2.1                               Warrant
Price. During the period specified in Section 2.2, each Warrant shall,
subject to the terms of this Warrant Agreement and the applicable Warrant
Certificate, entitle the holder thereof to purchase the number of Warrant Securities
specified in the applicable Warrant Certificate at an exercise price of
$                 
per Warrant Security, subject to adjustment upon the occurrence of certain
events to an exercise price not less than the par value of the Warrant
Securities, as hereinafter provided. Such purchase price per Warrant Security
is referred to in this Agreement as the “WARRANT PRICE.”

 

2.2                               Duration
of Warrants. Each Warrant may be exercised in whole or in part at any time,
as specified herein, on or after [the date thereof]
[            ] and
at or before          p.m., [City]
time, on
             or
such later date as the Company may designate by notice to the Warrant Agent and
the holders of Warrant Certificates mailed to their addresses as set forth in
the record books of the Warrant Agent (the “EXPIRATION DATE”). Each Warrant not
exercised at or before
           p.m., [City]
time, on the Expiration Date shall become void, and all rights of the holder of
the Warrant Certificate evidencing such Warrant under this Agreement shall
cease.

 

2.3                               Exercise
of Warrants.

 

(a)                                  During
the period specified in Section 2.2, the Warrants may be exercised to
purchase a whole number of Warrant Securities in registered form by providing
certain information as set forth on the reverse side of the Warrant Certificate
and by paying in full, in lawful money of the United States of America, [in
cash or by certified check or official bank check in New York Clearing House
funds] [by bank wire transfer in immediately available funds] the Warrant Price
for each Warrant Security with respect to which a Warrant is being exercised to
the Warrant Agent at its corporate trust office, provided that such exercise is
subject

 

3

 

to receipt within five business days of such payment
by the Warrant Agent of the Warrant Certificate with the form of election to
purchase Warrant Securities set forth on the reverse side of the Warrant
Certificate properly completed and duly executed. The date on which payment in
full of the Warrant Price is received by the Warrant Agent shall, subject to
receipt of the Warrant Certificate as aforesaid, be deemed to be the date on
which the Warrant is exercised; provided, however, that if, at the date of
receipt of such Warrant Certificates and payment in full of the Warrant Price,
the transfer books for the Warrant Securities purchasable upon the exercise of
such Warrants shall be closed, no such receipt of such Warrant Certificates and
no such payment of such Warrant Price shall be effective to constitute the
person so designated to be named as the holder of record of such Warrant
Securities on such date, but shall be effective to constitute such person as
the holder of record of such Warrant Securities for all purposes at the opening
of business on the next succeeding day on which the transfer books for the
Warrant Securities purchasable upon the exercise of such Warrants shall be
opened, and the certificates for the Warrant Securities in respect of which
such Warrants are then exercised shall be issuable as of the date on such next
succeeding day on which the transfer books shall next be opened, and until such
date the Company shall be under no duty to deliver any certificate for such
Warrant Securities. The Warrant Agent shall deposit all funds received by it in
payment of the Warrant Price in an account of the Company maintained with it
and shall advise the Company by telephone at the end of each day on which a
payment for the exercise of Warrants is received of the amount so deposited to
its account. The Warrant Agent shall promptly confirm such telephone advice to
the Company in writing.

 

(b)                                  The
Warrant Agent shall, from time to time, as promptly as practicable, advise the
Company of (i) the number of Warrant Securities with respect to which
Warrants were exercised, (ii) the instructions of each holder of the
Warrant Certificates evidencing such Warrants with respect to delivery of the
Warrant Securities to which such holder is entitled upon such exercise, (iii) delivery
of Warrant Certificates evidencing the balance, if any, of the Warrants for the
remaining Warrant Securities after such exercise, and (iv) such other
information as the Company shall reasonably require.

 

(c)                                  As
soon as practicable after the exercise of any Warrant, the Company shall issue
to or upon the order of the holder of the Warrant Certificate evidencing such
Warrant the Warrant Securities to which such holder is entitled, in fully
registered form, registered in such name or names as may be directed by such
holder. If fewer than all of the Warrants evidenced by such Warrant Certificate
are exercised, the Company shall execute, and an authorized officer of the
Warrant Agent shall manually countersign and deliver, a new Warrant Certificate
evidencing Warrants for the number of Warrant Securities remaining unexercised.

 

(d)                                  The
Company shall not be required to pay any stamp or other tax or other
governmental charge required to be paid in connection with any transfer
involved in the issue of the Warrant Securities, and in the event that any such
transfer is involved, the Company shall not be required to issue or deliver any
Warrant Security until such tax or other charge shall have been paid or it has
been established to the Company’s satisfaction that no such tax or other charge
is due.

 

(e)                                  Prior
to the issuance of any Warrants there shall have been reserved, and the Company
shall at all times through the Expiration Date keep reserved, out of its
authorized

 

4

 

but unissued Warrant Securities, a number of shares
sufficient to provide for the exercise of the Warrants.

 

ARTICLE 3

 

OTHER PROVISIONS RELATING TO RIGHTS OF HOLDERS OF
WARRANT CERTIFICATES

 

3.1                               No
Rights As Warrant Securityholder Conferred By Warrants or Warrant Certificates.
No Warrant Certificate or Warrant evidenced thereby shall entitle the holder
thereof to any of the rights of a holder of Warrant Securities, including,
without limitation, the right to receive the payment of dividends or
distributions, if any, on the Warrant Securities or to exercise any voting
rights, except to the extent expressly set forth in this Agreement or the
applicable Warrant Certificate.

 

3.2                               Lost,
Stolen, Mutilated or Destroyed Warrant Certificates. Upon receipt by the
Warrant Agent of evidence reasonably satisfactory to it and the Company of the
ownership of and the loss, theft, destruction or mutilation of any Warrant
Certificate and/or indemnity reasonably satisfactory to the Warrant Agent and
the Company and, in the case of mutilation, upon surrender of the mutilated
Warrant Certificate to the Warrant Agent for cancellation, then, in the absence
of notice to the Company or the Warrant Agent that such Warrant Certificate has
been acquired by a bona fide purchaser, the Company shall execute, and an
authorized officer of the Warrant Agent shall manually countersign and deliver,
in exchange for or in lieu of the lost, stolen, destroyed or mutilated Warrant
Certificate, a new Warrant Certificate of the same tenor and evidencing Warrants
for a like number of Warrant Securities. Upon the issuance of any new Warrant
Certificate under this Section 3.2, the Company may require the payment of
a sum sufficient to cover any tax or other governmental charge that may be
imposed in relation thereto and any other expenses (including the fees and
expenses of the Warrant Agent) in connection therewith. Every substitute
Warrant Certificate executed and delivered pursuant to this Section 3.2 in
lieu of any lost, stolen or destroyed Warrant Certificate shall represent an
additional contractual obligation of the Company, whether or not the lost,
stolen or destroyed Warrant Certificate shall be at any time enforceable by
anyone, and shall be entitled to the benefits of this Agreement equally and proportionately
with any and all other Warrant Certificates duly executed and delivered
hereunder. The provisions of this Section 3.2 are exclusive and shall
preclude (to the extent lawful) all other rights and remedies with respect to
the replacement of mutilated, lost, stolen or destroyed Warrant Certificates.

 

3.3                               Holder
of Warrant Certificate May Enforce Rights. Notwithstanding any of the
provisions of this Agreement, any holder of a Warrant Certificate, without the
consent of the Warrant Agent, the holder of any Warrant Securities or the
holder of any other Warrant Certificate, may, in such holder’s own behalf and
for such holder’s own benefit, enforce, and may institute and maintain any
suit, action or proceeding against the Company suitable to enforce, or otherwise
in respect of, such holder’s right to exercise the Warrants evidenced by such
holder’s Warrant Certificate in the manner provided in such holder’s Warrant
Certificate and in this Agreement.

 

5

 

3.4                               Adjustments.

 

(a)                                  In
case the Company shall at any time subdivide its outstanding shares of [title
of Preferred Stock purchasable through exercise of Warrants] into a greater
number of shares, the Warrant Price in effect immediately prior to such
subdivision shall be proportionately reduced and the number of Warrant
Securities purchasable under the Warrants shall be proportionately increased.
Conversely, in case the outstanding shares of [title of Preferred Stock
purchasable through exercise of Warrants] of the Company shall be combined into
a smaller number of shares, the Warrant Price in effect immediately prior to
such combination shall be proportionately increased and the number of Warrant
Securities purchasable under the Warrants shall be proportionately decreased.

 

(b)                                  If
at any time or from time to time the holders of [title of Preferred Stock
purchasable through exercise of Warrants] (or any shares of stock or other
securities at the time receivable upon the exercise of the Warrants) shall have
received or become entitled to receive, without payment therefore,

 

(i)                                    [title
of Preferred Stock purchasable through exercise of Warrants] or any shares of
stock or other securities which are at any time directly or indirectly
convertible into or exchangeable for [title of Preferred Stock purchasable
through exercise of Warrants], or any rights or options to subscribe for,
purchase or otherwise acquire any of the foregoing by way of dividend or other
distribution;

 

(ii)                                any
cash paid or payable otherwise than in accordance with the terms of [title of
Preferred Stock purchasable through exercise of Warrants] or otherwise than as
a cash dividend paid or payable out of the Company’s current or retained
earnings;

 

(iii)                            any
evidence of the Company’s indebtedness or rights to subscribe for or purchase
the Company’s indebtedness; or

 

(iv)                               [title
of Preferred Stock purchasable through exercise of Warrants] or additional
stock or other securities or property (including cash) by way of spinoff,
split-up, reclassification, combination of shares or similar corporate
rearrangement (other than shares of [title of Preferred Stock purchasable
through exercise of Warrants] issued as a stock split or adjustments in respect
of which shall be covered by the terms of Section 3.4(a) above), then
and in each such case, the holder of each Warrant shall, upon the exercise of
the Warrant, be entitled to receive, in addition to the number of Warrant
Securities receivable thereupon, and without payment of any additional
consideration therefore, the amount of stock and other securities and property
(including cash and indebtedness (or rights to subscribe for or purchase
indebtedness) which such holder would hold on the date of such exercise had he
been the holder of record of such Warrant Securities as of the date on which
holders of [title of Preferred Stock purchasable through exercise of Warrants]
received or became entitled to receive such shares or all other additional
stock and other securities and property.

 

(c)                                  In
case of (i) any reclassification, capital reorganization, or change in the
[title of Preferred Stock purchasable through the exercise of the Warrants] of
the Company (other than as a result of a subdivision, combination or stock
dividend provided for in Section 3.4(a) or

 

6

 

Section 3.4(b) above), (ii) share
exchange, merger or similar transaction of the Company with or into another
person or entity (other than a share exchange, merger or similar transaction in
which the Company is the acquiring or surviving corporation and which does not
result in any change in the [title of Preferred Stock purchasable through the
exercise of the Warrants] other than the issuance of additional shares of
[title of Preferred Stock purchasable through the exercise of the Warrants]) or
(iii) the sale, exchange, lease, transfer or other disposition of all or
substantially all of the properties and assets of the Company as an entirety
(in any such case, a “REORGANIZATION EVENT”), then, as a condition of such
Reorganization Event, lawful provisions shall be made, and duly executed
documents evidencing the same from the Company or its successor shall be
delivered to the holders of the Warrants, so that the holders of the Warrants
shall have the right at any time prior to the expiration of the Warrants to
purchase, at a total price equal to that payable upon the exercise of the
Warrants, the kind and amount of shares of stock and other securities and
property receivable in connection with such Reorganization Event by a holder of
the same number of shares of [title of Preferred Stock purchasable through the
exercise of the Warrants] as were purchasable by the holders of the Warrants
immediately prior to such Reorganization Event. In any such case appropriate provisions
shall be made with respect to the rights and interests of the holders of the
Warrants so that the provisions hereof shall thereafter be applicable with
respect to any shares of stock or other securities and property deliverable
upon exercise the Warrants, and appropriate adjustments shall be made to the
Warrant Price payable hereunder provided the aggregate purchase price shall
remain the same. In the case of any transaction described in clauses (ii) and
(iii) above, the Company shall thereupon be relieved of any further
obligation hereunder or under the Warrants, and the Company as the predecessor
corporation may thereupon or at any time thereafter be dissolved, wound up or
liquidated. Such successor or assuming entity thereupon may cause to be signed,
and may issue either in its own name or in the name of the Company, any or all
of the Warrants issuable hereunder which heretofore shall not have been signed
by the Company, and may execute and deliver securities in its own name, in
fulfillment of its obligations to deliver Warrant Securities upon exercise of
the Warrants. All the Warrants so issued shall in all respects have the same
legal rank and benefit under this Agreement as the Warrants theretofore or
thereafter issued in accordance with the terms of this Agreement as though all
of such Warrants had been issued at the date of the execution hereof. In any
case of any such Reorganization Event, such changes in phraseology and form
(but not in substance) may be made in the Warrants thereafter to be issued as
may be appropriate.

 

The Warrant Agent may receive a written opinion of
legal counsel as conclusive evidence that any such Reorganization Event
complies with the provisions of this Section 3.4.

 

(d)                                  The
Company may, at its option, at any time until the Expiration Date, reduce the
then current Warrant Price to any amount deemed appropriate by the Board of
Directors of the Company for any period not exceeding twenty consecutive days
(as evidenced in a resolution adopted by such Board of Directors), but only
upon giving the notices required by Section 3.5 at least ten days prior to
taking such action.

 

(e)                                  Except
as herein otherwise expressly provided, no adjustment in the Warrant Price
shall be made by reason of the issuance of any securities of the Company or for
any other reason whatsoever.

 

7

 

(f)                                    No
fractional Warrant Securities shall be issued upon the exercise of Warrants. If
more than one Warrant shall be exercised at one time by the same holder, the
number of full Warrant Securities which shall be issuable upon such exercise
shall be computed on the basis of the aggregate number of Warrant Securities
purchased pursuant to the Warrants so exercised. Instead of any fractional
Warrant Security which would otherwise be issuable upon exercise of any
Warrant, the Company shall pay a cash adjustment in respect of such fraction in
an amount equal to the same fraction of the last sales price (or bid price if
there were no sales) per Warrant Security, in either case as reported on the
New York Stock Exchange Composite Tape on the business day which next precedes
the day of exercise or, if the Warrant Securities are not then listed or
admitted to trading on the New York Stock Exchange, on the principal national securities
exchange on which the Warrant Securities are listed or admitted to trading or,
if not listed or admitted to trading on any national securities exchange, on
the NASDAQ Stock Market system of the National Association of Securities
Dealers, Inc. Automated Quotations System (“NASDAQ”), or if the Warrant
Securities are not then listed or admitted to trading on any national
securities exchange or quoted on the NASDAQ Stock Market system of NASDAQ, the
average of the closing high bid and low asked prices in the over-the-counter
market, as reported by NASDAQ, or such other system then in use, or if on any
such date the Warrant Securities are not quoted by any such organization, an
amount equal to the same fraction of the average of the closing bid and asked
prices as furnished by any New York Stock Exchange firm selected from time to
time by the Company for that purpose at the close of business on the business
day which next precedes the day of exercise.

 

(g)                                 Whenever
the Warrant Price then in effect is adjusted as herein provided, the Company
shall mail to each holder of the Warrants at such holder’s address as it shall
appear on the books of the Company a statement setting forth the adjusted
Warrant Price then and thereafter effective under the provisions hereof,
together with the facts, in reasonable detail, upon which such adjustment is
based.

 

3.5                               Notice
to Warrantholders.   In case the
Company shall (a) effect any dividend or distribution described in Section 3.4(b),
(b) effect any Reorganization Event, (c) make any distribution on or
in respect of the [title of Preferred Stock purchasable through the exercise of
the Warrants] in connection with the dissolution, liquidation or winding up of
the Company, or (d) reduce the then current Warrant Price pursuant to Section 3.4(d),
then the Company shall mail to each holder of Warrants at such holder’s address
as it shall appear on the books of the Warrant Agent, at least ten days prior
to the applicable date hereinafter specified, a notice stating (x) the
record date for such dividend or distribution, or, if a record is not to be
taken, the date as of which the holders of record of [title of Preferred Stock
purchasable through the exercise of Warrants] that will be entitled to such
dividend or distribution are to be determined, (y) the date on which such
Reorganization Event, dissolution, liquidation or winding up is expected to
become effective, and the date as of which it is expected that holders of
[title of Preferred Stock purchasable through the exercise of the Warrants] of
record shall be entitled to exchange their shares of [title of Preferred Stock
purchasable through the exercise of the Warrants] for securities or other
property deliverable upon such Reorganization Event, dissolution, liquidation
or winding up, or (z) the first date on which the then current Warrant
Price shall be reduced pursuant to Section 3.4(d). No failure to mail such
notice nor any defect therein or in the mailing thereof shall affect any such
transaction or any adjustment in the Warrant Price required by Section 3.4.

 

8

 

3.6          [IF THE WARRANTS ARE SUBJECT TO
ACCELERATION BY THE COMPANY, INSERT—ACCELERATION OF WARRANTS BY THE COMPANY.

 

(a)           At any time on or
after
                       ,
the Company shall have the right to accelerate any or all Warrants at any time
by causing them to expire at the close of business on the day next preceding a
specified date (the “ACCELERATION DATE”), if the Market Price (as hereinafter
defined) of the [title of Preferred Stock purchasable through the exercise of
the Warrants] equals or exceeds
                 
percent (   %) of the then effective Warrant Price on any twenty
Trading Days (as hereinafter defined) within a period of thirty consecutive
Trading Days ending no more than five Trading Days prior to the date on which
the Company gives notice to the Warrant Agent of its election to accelerate the
Warrants.

 

(b)           “Market Price” for
each Trading Day shall be, if the [title of Preferred Stock purchasable through
the exercise of the Warrants] is listed or admitted for trading on the New York
Stock Exchange, the last reported sale price, regular way (or, if no such price
is reported, the average of the reported closing bid and asked prices, regular
way) of [title of Preferred Stock purchasable through the exercise of the
Warrants], in either case as reported on the New York Stock Exchange Composite
Tape or, if the [title of Preferred Stock purchasable through the exercise of
the Warrants]is not listed or admitted to trading on the New York Stock
Exchange, on the principal national securities exchange on which the [title of
Preferred Stock purchasable through the exercise of the Warrants] is listed or
admitted to trading or, if not listed or admitted to trading on any national
securities exchange, on the NASDAQ Stock Market system of NASDAQ or, if not
listed or admitted to trading on any national securities exchange or quoted on
the NASDAQ Stock Market system of NASDAQ, the average of the closing high bid
and low asked prices in the over-the-counter market, as reported by NASDAQ, or
such other system then in use, or if on any such date the shares of [title of
Preferred Stock purchasable through the exercise of the Warrants] are not
quoted by any such organization, the average of the closing bid and asked
prices as furnished by any New York Stock Exchange firm selected from time to
time by the Company for that purpose. “Trading Day” shall be each Monday
through Friday, other than any day on which securities are not traded in the
system or on the exchange that is the principal market for the [title of
Preferred Stock purchasable through the exercise of the Warrants], as
determined by the Board of Directors of the Company.

 

(c)           In the event of an
acceleration of less than all of the Warrants, the Warrant Agent shall select
the Warrants to be accelerated by lot, pro rata or in such other manner as it
deems, in its discretion, to be fair and appropriate.

 

(d)           Notice of an
acceleration specifying the Acceleration Date shall be sent by mail first
class, postage prepaid, to each registered holder of a Warrant Certificate
representing a Warrant accelerated at such holder’s address appearing on the
books of the Warrant Agent not more than sixty days nor less than thirty days
before the Acceleration Date. Such notice of an acceleration also shall be
given no more than twenty days, and no less than ten days, prior to the mailing
of notice to registered holders of Warrants pursuant to this Section 3.6,
by publication at least once in a newspaper of general circulation in the City
of New York.

 

9

 

(e)           Any Warrant
accelerated may be exercised until
          p.m., [City] time,
on the business day next preceding the Acceleration Date. The Warrant Price
shall be payable as provided in Section 2.]

 

ARTICLE 4

 

EXCHANGE AND TRANSFER OF WARRANT CERTIFICATES

 

4.1          Exchange and Transfer of Warrant
Certificates. [If Other Securities with Warrants which are
immediately detachable—Upon] [If Other Securities with Warrants which are not
immediately detachable—Prior to the Detachable Date, a Warrant Certificate may
be exchanged or transferred only together with the Other Security to which the
Warrant Certificate was initially attached, and only for the purpose of
effecting or in conjunction with an exchange or transfer of such Other Security.
Prior to any Detachable Date, each transfer of the Other Security shall operate
also to transfer the related Warrant Certificates. After the Detachable Date,
upon] surrender at the corporate trust office of the Warrant Agent, Warrant
Certificates evidencing Warrants may be exchanged for Warrant Certificates in
other denominations evidencing such Warrants or the transfer thereof may be
registered in whole or in part; provided that such other Warrant Certificates
evidence Warrants for the same aggregate number of Warrant Securities as the
Warrant Certificates so surrendered. The Warrant Agent shall keep, at its
corporate trust office, books in which, subject to such reasonable regulations
as it may prescribe, it shall register Warrant Certificates and exchanges and
transfers of outstanding Warrant Certificates, upon surrender of the Warrant
Certificates to the Warrant Agent at its corporate trust office for exchange or
registration of transfer, properly endorsed or accompanied by appropriate
instruments of registration of transfer and written instructions for transfer,
all in form satisfactory to the Company and the Warrant Agent. No service
charge shall be made for any exchange or registration of transfer of Warrant
Certificates, but the Company may require payment of a sum sufficient to cover
any stamp or other tax or other governmental charge that may be imposed in
connection with any such exchange or registration of transfer. Whenever any
Warrant Certificates are so surrendered for exchange or registration of
transfer, an authorized officer of the Warrant Agent shall manually countersign
and deliver to the person or persons entitled thereto a Warrant Certificate or
Warrant Certificates duly authorized and executed by the Company, as so
requested. The Warrant Agent shall not be required to effect any exchange or
registration of transfer which will result in the issuance of a Warrant
Certificate evidencing a Warrant for a fraction of a Warrant Security or a
number of Warrants for a whole number of Warrant Securities and a fraction of a
Warrant Security. All Warrant Certificates issued upon any exchange or
registration of transfer of Warrant Certificates shall be the valid obligations
of the Company, evidencing the same obligations and entitled to the same benefits
under this Agreement as the Warrant Certificate surrendered for such exchange
or registration of transfer.

 

4.2          Treatment of Holders of Warrant
Certificates. [If Other Securities and Warrants are not
immediately detachable—Prior to the Detachable Date, the Company, the Warrant
Agent and all other persons may treat the owner of the Other Security as the
owner of the Warrant Certificates initially attached thereto for any purpose
and as the person entitled to exercise the rights represented by the Warrants
evidenced by such Warrant Certificates, any notice to the contrary
notwithstanding. After the Detachable Date and prior to due presentment of a
Warrant Certificate for registration of transfer, the] [T]he Company, the
Warrant Agent and

 

10

 

all other persons may treat the registered holder of a
Warrant Certificate as the absolute owner thereof for any purpose and as the
person entitled to exercise the rights represented by the Warrants evidenced
thereby, any notice to the contrary notwithstanding.

 

4.3          Cancellation of Warrant Certificates.
Any Warrant Certificate surrendered for exchange, registration of transfer or
exercise of the Warrants evidenced thereby shall, if surrendered to the
Company, be delivered to the Warrant Agent and all Warrant Certificates
surrendered or so delivered to the Warrant Agent shall be promptly canceled by
the Warrant Agent and shall not be reissued and, except as expressly permitted
by this Agreement, no Warrant Certificate shall be issued hereunder in exchange
therefor or in lieu thereof. The Warrant Agent shall deliver to the Company
from time to time or otherwise dispose of canceled Warrant Certificates in a
manner satisfactory to the Company.

 

ARTICLE 5

 

CONCERNING THE WARRANT AGENT

 

5.1          Warrant Agent. The
Company hereby appoints
                  
as Warrant Agent of the Company in respect of the Warrants and the Warrant
Certificates upon the terms and subject to the conditions herein set forth, and
                
hereby accepts such appointment. The Warrant Agent shall have the powers and
authority granted to and conferred upon it in the Warrant Certificates and
hereby and such further powers and authority to act on behalf of the Company as
the Company may hereafter grant to or confer upon it. All of the terms and
provisions with respect to such powers and authority contained in the Warrant
Certificates are subject to and governed by the terms and provisions hereof.

 

5.2          Conditions of Warrant Agent’s
Obligations. The Warrant Agent accepts its obligations herein
set forth upon the terms and conditions hereof, including the following to all
of which the Company agrees and to all of which the rights hereunder of the
holders from time to time of the Warrant Certificates shall be subject:

 

(a)           Compensation and Indemnification.
The Company agrees promptly to pay the Warrant Agent the compensation to be
agreed upon with the Company for all services rendered by the Warrant Agent and
to reimburse the Warrant Agent for reasonable out-of-pocket expenses (including
reasonable counsel fees) incurred without negligence, bad faith or willful
misconduct by the Warrant Agent in connection with the services rendered
hereunder by the Warrant Agent. The Company also agrees to indemnify the Warrant
Agent for, and to hold it harmless against, any loss, liability or expense
incurred without negligence, bad faith or willful misconduct on the part of the
Warrant Agent, arising out of or in connection with its acting as Warrant Agent
hereunder, including the reasonable costs and expenses of defending against any
claim of such liability.

 

(b)           Agent for the Company.
In acting under this Warrant Agreement and in connection with the Warrant
Certificates, the Warrant Agent is acting solely as agent of the Company and
does not assume any obligations or relationship of agency or trust for or with
any of the holders of Warrant Certificates or beneficial owners of Warrants.

 

11

 

(c)           Counsel. The
Warrant Agent may consult with counsel satisfactory to it, which may include
counsel for the Company, and the written advice of such counsel shall be full
and complete authorization and protection in respect of any action taken,
suffered or omitted by it hereunder in good faith and in accordance with the
advice of such counsel.

 

(d)           Documents. The
Warrant Agent shall be protected and shall incur no liability for or in respect
of any action taken or omitted by it in reliance upon any Warrant Certificate,
notice, direction, consent, certificate, affidavit, statement or other paper or
document reasonably believed by it to be genuine and to have been presented or
signed by the proper parties.

 

(e)           Certain Transactions.
The Warrant Agent, and its officers, directors and employees, may become the
owner of, or acquire any interest in, Warrants, with the same rights that it or
they would have if it were not the Warrant Agent hereunder, and, to the extent
permitted by applicable law, it or they may engage or be interested in any
financial or other transaction with the Company and may act on, or as
depositary, trustee or agent for, any committee or body of holders of Warrant
Securities or other obligations of the Company as freely as if it were not the
Warrant Agent hereunder. Nothing in this Warrant Agreement shall be deemed to
prevent the Warrant Agent from acting as trustee under any indenture to which
the Company is a party.

 

(f)            No Liability for Interest.
Unless otherwise agreed with the Company, the Warrant Agent shall have no
liability for interest on any monies at any time received by it pursuant to any
of the provisions of this Agreement or of the Warrant Certificates.

 

(g)           No Liability for Invalidity.
The Warrant Agent shall have no liability with respect to any invalidity of
this Agreement or any of the Warrant Certificates (except as to the Warrant
Agent’s countersignature thereon).

 

(h)           No Responsibility for Representations.
The Warrant Agent shall not be responsible for any of the recitals or
representations herein or in the Warrant Certificates (except as to the Warrant
Agent’s countersignature thereon), all of which are made solely by the Company.

 

(i)            No Implied Obligations.
The Warrant Agent shall be obligated to perform only such duties as are herein
and in the Warrant Certificates specifically set forth and no implied duties or
obligations shall be read into this Agreement or the Warrant Certificates
against the Warrant Agent. The Warrant Agent shall not be under any obligation
to take any action hereunder which may tend to involve it in any expense or
liability, the payment of which within a reasonable time is not, in its
reasonable opinion, assured to it. The Warrant Agent shall not be accountable
or under any duty or responsibility for the use by the Company of any of the
Warrant Certificates authenticated by the Warrant Agent and delivered by it to
the Company pursuant to this Agreement or for the application by the Company of
the proceeds of the Warrant Certificates. The Warrant Agent shall have no duty
or responsibility in case of any default by the Company in the performance of
its covenants or agreements contained herein or in the Warrant Certificates or
in the case of the receipt of any written demand from a holder of a Warrant
Certificate with respect to such default, including, without limiting the
generality of the

 

12

 

foregoing, any duty or responsibility to initiate or
attempt to initiate any proceedings at law or otherwise or, except as provided
in Section 6.2 hereof, to make any demand upon the Company.

 

5.3          Resignation and Appointment of
Successor.

 

(a)           The Company agrees,
for the benefit of the holders from time to time of the Warrant Certificates,
that there shall at all times be a Warrant Agent hereunder until all the
Warrants have been exercised or are no longer exercisable.

 

(b)           The Warrant Agent
may at any time resign as agent by giving written notice to the Company of such
intention on its part, specifying the date on which its desired resignation
shall become effective; provided that such date shall not be less than three
months after the date on which such notice is given unless the Company
otherwise agrees. The Warrant Agent hereunder may be removed at any time by the
filing with it of an instrument in writing signed by or on behalf of the
Company and specifying such removal and the intended date when it shall become
effective. Such resignation or removal shall take effect upon the appointment
by the Company, as hereinafter provided, of a successor Warrant Agent (which
shall be a bank or trust company authorized under the laws of the jurisdiction
of its organization to exercise corporate trust powers) and the acceptance of
such appointment by such successor Warrant Agent. The obligation of the Company
under Section 5.2(a) shall continue to the extent set forth therein
notwithstanding the resignation or removal of the Warrant Agent.

 

(c)           In case at any time
the Warrant Agent shall resign, or shall be removed, or shall become incapable
of acting, or shall be adjudged a bankrupt or insolvent, or shall commence a
voluntary case under the Federal bankruptcy laws, as now or hereafter
constituted, or under any other applicable Federal or state bankruptcy,
insolvency or similar law or shall consent to the appointment of or taking
possession by a receiver, custodian, liquidator, assignee, trustee,
sequestrator (or other similar official) of the Warrant Agent or its property
or affairs, or shall make an assignment for the benefit of creditors, or shall
admit in writing its inability to pay its debts generally as they become due,
or shall take corporate action in furtherance of any such action, or a decree
or order for relief by a court having jurisdiction in the premises shall have
been entered in respect of the Warrant Agent in an involuntary case under the
Federal bankruptcy laws, as now or hereafter constituted, or any other
applicable Federal or state bankruptcy, insolvency or similar law, or a decree
or order by a court having jurisdiction in the premises shall have been entered
for the appointment of a receiver, custodian, liquidator, assignee, trustee,
sequestrator (or similar official) of the Warrant Agent or of its property or
affairs, or any public officer shall take charge or control of the Warrant
Agent or of its property or affairs for the purpose of rehabilitation,
conservation, winding up or liquidation, a successor Warrant Agent, qualified
as aforesaid, shall be appointed by the Company by an instrument in writing,
filed with the successor Warrant Agent. Upon the appointment as aforesaid of a
successor Warrant Agent and acceptance by the successor Warrant Agent of such
appointment, the Warrant Agent shall cease to be Warrant Agent hereunder.

 

(d)           Any successor
Warrant Agent appointed hereunder shall execute, acknowledge and deliver to its
predecessor and to the Company an instrument accepting such appointment
hereunder, and thereupon such successor Warrant Agent, without any further act,
deed or conveyance, shall become vested with all the authority, rights, powers,
trusts,

 

13

 

immunities, duties and obligations of such predecessor
with like effect as if originally named as Warrant Agent hereunder, and such
predecessor, upon payment of its charges and disbursements then unpaid, shall
thereupon become obligated to transfer, deliver and pay over, and such
successor Warrant Agent shall be entitled to receive, all monies, securities
and other property on deposit with or held by such predecessor, as Warrant
Agent hereunder.

 

(e)           Any corporation
into which the Warrant Agent hereunder may be merged or converted or any
corporation with which the Warrant Agent may be consolidated, or any
corporation resulting from any merger, conversion or consolidation to which the
Warrant Agent shall be a party, or any corporation to which the Warrant Agent
shall sell or otherwise transfer all or substantially all the assets and
business of the Warrant Agent, provided that it shall be qualified as
aforesaid, shall be the successor Warrant Agent under this Agreement without
the execution or filing of any paper or any further act on the part of any of
the parties hereto.

 

ARTICLE 6

 

MISCELLANEOUS

 

6.1          Amendment. This
Agreement may be amended by the parties hereto, without the consent of the holder
of any Warrant Certificate, for the purpose of curing any ambiguity, or of
curing, correcting or supplementing any defective provision contained herein,
or making any other provisions with respect to matters or questions arising
under this Agreement as the Company and the Warrant Agent may deem necessary or
desirable; provided that such action shall not materially adversely affect the
interests of the holders of the Warrant Certificates.

 

6.2          Notices and Demands to the Company and
Warrant Agent. If the Warrant Agent shall receive any notice
or demand addressed to the Company by the holder of a Warrant Certificate
pursuant to the provisions of the Warrant Certificates, the Warrant Agent shall
promptly forward such notice or demand to the Company.

 

6.3          Addresses. Any
communication from the Company to the Warrant Agent with respect to this
Agreement shall be addressed to
                           ,
Attention:
                 
and any communication from the Warrant Agent to the Company with respect to
this Agreement shall be addressed to Allos Therapeutics, Inc., 11080
CirclePoint Road, Suite 200, Westminster, Colorado 80020, Attention:  Corporate Secretary (or such other address as
shall be specified in writing by the Warrant Agent or by the Company).

 

6.4          Governing Law. This
Agreement and each Warrant Certificate issued hereunder shall be governed by
and construed in accordance with the laws of the State of New York.

 

6.5          Delivery of Prospectus.
The Company shall furnish to the Warrant Agent sufficient copies of a
prospectus meeting the requirements of the Securities Act of 1933, as amended,
relating to the Warrant Securities deliverable upon exercise of the Warrants
(the “PROSPECTUS”), and the Warrant Agent agrees that upon the exercise of any
Warrant, the Warrant Agent will deliver to the holder of the Warrant
Certificate evidencing such Warrant, prior to or concurrently with the delivery
of the Warrant Securities issued upon such exercise, a Prospectus.

 

14

 

The Warrant Agent shall not, by reason of any such
delivery, assume any responsibility for the accuracy or adequacy of such
Prospectus.

 

6.6          Obtaining of Governmental Approvals.
The Company will from time to time take all action which may be necessary to obtain
and keep effective any and all permits, consents and approvals of governmental
agencies and authorities and securities act filings under United States Federal
and state laws (including without limitation a registration statement in
respect of the Warrants and Warrant Securities under the Securities Act of
1933, as amended), which may be or become requisite in connection with the
issuance, sale, transfer, and delivery of the Warrant Securities issued upon
exercise of the Warrants, the issuance, sale, transfer and delivery of the
Warrants or upon the expiration of the period during which the Warrants are
exercisable.

 

6.7          Persons Having Rights Under Warrant
Agreement. Nothing in this Agreement shall give to any person
other than the Company, the Warrant Agent and the holders of the Warrant
Certificates any right, remedy or claim under or by reason of this Agreement.

 

6.8          Headings. The
descriptive headings of the several Articles and Sections of this Agreement are
inserted for convenience only and shall not control or affect the meaning or
construction of any of the provisions hereof.

 

6.9          Counterparts. This
Agreement may be executed in any number of counterparts, each of which as so
executed shall be deemed to be an original, but such counterparts shall together
constitute but one and the same instrument.

 

6.10        Inspection of Agreement.
A copy of this Agreement shall be available at all reasonable times at the
principal corporate trust office of the Warrant Agent for inspection by the
holder of any Warrant Certificate. The Warrant Agent may require such holder to
submit his Warrant Certificate for inspection by it.

 

15

 

IN WITNESS WHEREOF, the parties hereto have caused
this Agreement to be duly executed, all as of the day and year first above
written.

 

	
  

  	
  ALLOS THERAPEUTICS, INC.

  
	
   

  	
   

  
	
   

  	
  By:

  	
   

  
	
   

  	
  Its:

  	
   

  
	
   

  	
   

  	
   

  
	
  Attest:

  	
   

  	
   

  
	
   

  	
   

  	
   

  
	
   

  	
   

  	
   

  
	
   

  	
   

  	
   

  
	
   

  	
  Warrant Agent

  
	
   

  	
   

  
	
   

  	
  By:

  	
   

  
	
   

  	
  Its:

  	
   

  
	
   

  	
   

  	
   

  
	
  Attest:

  	
   

  	
   

  
	
   

  	
   

  	
   

  
	
   

  	
   

  	
   

  

 

[SIGNATURE PAGE TO
PREFERRED STOCK WARRANT AGREEMENT]

 

16

 

EXHIBIT
A

 

FORM OF
WARRANT CERTIFICATE

 

[FACE OF
WARRANT CERTIFICATE]

 

[[Form if Warrants
are attached to Other Securities and are not immediately detachable.]

 

[Prior to
               ,
this Warrant Certificate cannot be transferred or exchanged unless attached to
a [Title of Other Securities].]

 

[Form of Legend if
Warrants are not immediately exercisable.] [Prior to
           , Warrants
evidenced by this Warrant Certificate cannot be exercised.]

 

EXERCISABLE ONLY IF
COUNTERSIGNED BY THE WARRANT AGENT AS PROVIDED HEREIN

 

VOID AFTER
           P.M., [CITY]
TIME, ON
                  .

 

1

 

ALLOS
THERAPEUTICS, INC.

 

WARRANT
CERTIFICATE REPRESENTING

WARRANTS TO PURCHASE

[TITLE OF WARRANT SECURITIES]

 

	
  No.

  	
   

  	
  Warrants

  

 

This certifies that
                  
or registered assigns is the registered owner of the above indicated number of
Warrants, each Warrant entitling such owner [if Warrants are attached to Other
Securities and are not immediately detachable—, subject to the registered owner
qualifying as a “Holder” of this Warrant Certificate, as hereinafter defined),]
to purchase, at any time [after       p.m.,
[City] time, on           
and] on or before         p.m., [City]
time, on            
shares of [Title of Warrant Securities] (the “WARRANT SECURITIES”), of Allos
Therapeutics, Inc. (the “COMPANY”) on the following basis: during the
period from
             ,
through and including
             ,
the exercise price per Warrant Security will be
$          , subject to
adjustment as provided in the Warrant Agreement (as hereinafter defined) (the “WARRANT
PRICE”). The Holder may exercise the Warrants evidenced hereby by providing
certain information set forth on the back hereof and by paying in full, in
lawful money of the United States of America, [in cash or by certified check or
official bank check in New York Clearing House funds][by bank wire transfer in
immediately available funds], the Warrant Price for each Warrant Security with respect
to which this Warrant is exercised to the Warrant Agent (as hereinafter
defined) and by surrendering this Warrant Certificate, with the purchase form
on the back hereof duly executed, at the corporate trust office of [name of
Warrant Agent], or its successor as warrant agent (the “WARRANT AGENT”), which
is, on the date hereof, at the address specified on the reverse hereof, and
upon compliance with and subject to the conditions set forth herein and in the
Warrant Agreement (as hereinafter defined).

 

The term “HOLDER” as used herein shall mean [if
Warrants are attached to Other Securities and are not immediately
detachable—prior to
                
(the “DETACHABLE DATE”), the registered owner of the Company’s [title of Other
Securities] to which this Warrant Certificate was initially attached, and after
such Detachable Date,] the person in whose name at the time this Warrant
Certificate shall be registered upon the books to be maintained by the Warrant
Agent for that purpose pursuant to Section 4 of the Warrant Agreement.

 

The Warrants evidenced by this Warrant Certificate may
be exercised to purchase a whole number of Warrant Securities in registered
form. Upon any exercise of fewer than all of the Warrants evidenced by this
Warrant Certificate, there shall be issued to the Holder hereof a new Warrant
Certificate evidencing Warrants for the number of Warrant Securities remaining
unexercised.

 

This Warrant Certificate is issued under and in
accordance with the Warrant Agreement dated as of
                            
(the “WARRANT AGREEMENT”), between the Company and the Warrant Agent and is
subject to the terms and provisions contained in the Warrant Agreement, to all
of which terms and provisions the Holder of this Warrant Certificate consents
by acceptance hereof. Copies of the Warrant Agreement are on file at the
above-mentioned office of the Warrant Agent.

 

2

 

[If Warrants are attached to Other Securities and are
not immediately detachable—Prior to the Detachable Date, this Warrant
Certificate may be exchanged or transferred only together with the [Title of
Other Securities] (the “OTHER SECURITIES”) to which this Warrant Certificate
was initially attached, and only for the purpose of effecting or in conjunction
with, an exchange or transfer of such Other Security. Additionally, on or prior
to the Detachable Date, each transfer of such Other Security on the register of
the Other Securities shall operate also to transfer this Warrant Certificate.
After such date, transfer of this] [If Warrants are attached to Other
Securities and are immediately detachable—Transfer of this] Warrant Certificate
may be registered when this Warrant Certificate is surrendered at the corporate
trust office of the Warrant Agent by the registered owner or such owner’s
assigns, in the manner and subject to the limitations provided in the Warrant
Agreement.

 

[If Other Securities with Warrants which are not
immediately detachable—Except as provided in the immediately preceding
paragraph, after] [If Other Securities with Warrants which are immediately
detachable or Warrants alone—After] countersignature by the Warrant Agent and
prior to the expiration of this Warrant Certificate, this Warrant Certificate
may be exchanged at the corporate trust office of the Warrant Agent for Warrant
Certificates representing Warrants for the same aggregate number of Warrant
Securities.

 

This Warrant Certificate shall not entitle the Holder
hereof to any of the rights of a holder of the Warrant Securities, including,
without limitation, the right to receive payments of dividends or
distributions, if any, on the Warrant Securities (except to the extent set
forth in the Warrant Agreement) or to exercise any voting rights.

 

Reference is hereby made to the further provisions of
this Warrant Certificate set forth on the reverse hereof, which further
provisions shall for all purposes have the same effect as if set forth at this
place.

 

This Warrant Certificate shall be governed by and
construed in accordance with the laws of the State of New York.

 

This Warrant Certificate shall not be valid or
obligatory for any purpose until countersigned by the Warrant Agent.

 

3

 

IN WITNESS WHEREOF, the Company has caused this Warrant
to be executed in its name and on its behalf by the facsimile signatures of its
duly authorized officers.

 

	
  Dated:

  	
   

  	
   

  	
   

  	
   

  
	
   

  	
   

  	
   

  	
   

  	
   

  
	
   

  	
   

  	
   

  	
  ALLOS THERAPEUTICS, INC.

  
	
   

  	
   

  	
   

  	
   

  
	
   

  	
   

  	
   

  	
  By:

  	
   

  
	
   

  	
   

  	
   

  	
  Its:

  	
   

  
	
  Attest:

  	
   

  	
   

  	
   

  	
   

  
	
   

  	
   

  	
   

  
	
   

  	
   

  	
   

  
	
   

  	
   

  	
   

  	
   

  	
   

  
	
   

  	
   

  	
   

  	
  Countersigned:

  
	
   

  	
   

  	
   

  	
   

  
	
   

  	
   

  	
   

  	
  As Warrant Agent

  
	
   

  	
   

  	
   

  	
  By:

  	
   

  
	
   

  	
   

  	
   

  	
   

  	
  Authorized
  Signature

  
	
   

  	
   

  	
   

  	
   

  	
   

  
	
  Attest:

  	
   

  	
   

  	
   

  	
   

  
	
   

  	
   

  	
   

  	
   

  
	
   

  	
   

  	
   

  	
   

  
							

 

4

 

[REVERSE
OF WARRANT CERTIFICATE]

 

(Instructions
for Exercise of Warrant)

 

To exercise any Warrants evidenced hereby for Warrant
Securities (as hereinafter defined), the Holder must pay, in lawful money of
the United States of America, [in cash or by certified check or official bank
check in New York Clearing House funds] [by bank wire transfer in immediately
available funds], the Warrant Price in full for Warrants exercised, to [Warrant
Agent] [address of Warrant Agent], Attn:
             ,
which payment must specify the name of the Holder and the number of Warrants
exercised by such Holder. In addition, the Holder must complete the information
required below and present this Warrant Certificate in person or by mail
(certified or registered mail is recommended) to the Warrant Agent at the
appropriate address set forth above. This Warrant Certificate, completed and
duly executed, must be received by the Warrant Agent within five business days
of the payment.

 

(To be executed upon
exercise of Warrants)

 

5

 

The undersigned hereby irrevocably elects to exercise
               
Warrants, evidenced by this Warrant Certificate, to purchase
                 
shares of the [Title of Warrant Securities] (the “WARRANT SECURITIES”), of
Allos Therapeutics, Inc. and represents that he has tendered payment for
such Warrant Securities, in lawful money of the United States of America, [in
cash or by certified check or official bank check in New York Clearing House
funds] [by bank wire transfer in immediately available funds], to the order of
Allos Therapeutics, Inc., c/o [insert name and address of Warrant Agent],
in the amount of
$                
in accordance with the terms hereof. The undersigned requests that said Warrant
Securities be in fully registered form in the authorized denominations,
registered in such names and delivered all as specified in accordance with the
instructions set forth below.

 

If the number of Warrants exercised is less than all
of the Warrants evidenced hereby, the undersigned requests that a new Warrant
Certificate evidencing the Warrants for the number of Warrant Securities
remaining unexercised be issued and delivered to the undersigned unless
otherwise specified in the instructions below.

 

	
  Dated

  	
   

  	
   

  	
  Name

  	
   

  
	
   

  	
   

  	
   

  	
   

  	
  (Please Print)

  
	
  Address

  	
   

  	
   

  	
   

  	
   

  

 

 

(Insert Social
Security or Other Identifying Number of Holder)

 

	
  Signature Guaranteed

  	
   

  
	
   

  	
  Signature

  

 

 

(Signature must conform in all respects to name of
holder as specified on the face of this Warrant Certificate and must bear a
signature guarantee by a bank, trust company or member broker of the New York,
Midwest or Pacific Stock Exchange).

 

6

 

This Warrant may be
exercised at the following addresses:

 

	
  By hand at

  	
   

  
	
   

  	
   

  
	
   

  	
   

  
	
   

  	
   

  
	
  By mail at

  	
   

  
	
   

  	
   

  
	
   

  	
   

  

 

[Instructions as to form
and delivery of Warrant Securities and, if applicable, Warrant Certificates
evidencing Warrants for the number of Warrant Securities remaining
unexercised—complete as appropriate.]

 

7

 

ASSIGNMENT

 

[Form of assignment
to be executed if Warrant Holder desires to transfer Warrant)

 

FOR VALUE RECEIVED,
                            
hereby sells, assigns and transfers unto:

 

 

	
  

  	
   

  	
   

  
	
   

  	
   

  	
   

  
	
   

  	
   

  	
   

  
	
   

  	
   

  	
   

  
	
  (Please print
  name and address including zip code)

  	
   

  	
  Please insert Social Security or other identifying
  number

  

 

the right represented by
the within Warrant to purchase
               
shares of [Title of Warrant Securities] of Allos Therapeutics, Inc. to
which the within Warrant relates and appoints
                  
attorney to transfer such right on the books of the Warrant Agent with full
power of substitution in the premises.

 

	
  Dated

  	
   

  	
   

  	
   

  
	
   

  	
   

  	
   

  	
  Signature

  

 

 

(Signature must conform
in all respects to name of holder as specified on the face of the Warrant)

 

	
  Signature Guaranteed

  	
   

  
	
   

  	
   

  

 

8

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