Document:

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                                                                  Exhibit 4.3

THIS WARRANT MAY NOT BE SOLD OR OTHERWISE TRANSFERRED BY ANY PERSON, INCLUDING A
PLEDGEE, IN THE ABSENCE OF AN EFFECTIVE REGISTRATION STATEMENT FOR THE WARRANT
UNDER THE SECURITIES ACT OF 1933, AS AMENDED, AND APPLICABLE STATE SECURITIES
LAWS OR AN OPINION OF COUNSEL, SATISFACTORY TO THE COMPANY, THAT AN EXEMPTION
FROM REGISTRATION IS THEN AVAILABLE.

No. W-1                                                       For the Purchase
                                                           of 71,429 shares of
                                                                  Common Stock

                        WARRANT TO PURCHASE COMMON STOCK

                                       OF

            EXELIXIS PHARMACEUTICALS, INC., (A DELAWARE CORPORATION)

     VOID AFTER 5:00 P.M., EASTERN STANDARD TIME, ON JANUARY 27, 2005

     EXELIXIS PHARMACEUTICALS, INC., a Delaware corporation (the "COMPANY"), for
value received, hereby certifies that CREATIVE BIOMOLECULES, INC. or its
registered assigns (the "HOLDER"), is entitled, subject to the terms set forth
below, to purchase from the Company, at any time or from time to time at or
before the earlier of 5:00 p.m. Boston, Massachusetts time on January 27, 2005
and the termination of this Warrant as provided in Section 9 hereof, 71,429
shares of Common Stock. $.001 par value per share, of the Company (the "COMMON
STOCK"), at a purchase price of $0.70 per share, subject to adjustment upon the
occurrence of certain events set forth in this Warrant. The shares of Common
Stock issuable upon exercise of this Warrant, and the purchase price per share,
are hereinafter referred to an the "Warrant Stock" and the "PURCHASE PRICE,"
respectively.

     1. EXERCISE.

          1.1 MANNER OF EXERCISE; PAYMENT IN CASH. This Warrant may be
exercised by the Holder, in whole or in part, by surrendering this Warrant,
with the purchase form appended hereto as Exhibit A duly executed by the
Holder, at the principal office of the Company, or at such other place as the
Company may designate, accompanied by payment in full of the Purchase Price
payable in respect of the number of shares of Warrant Stock purchased upon
such exercise. Payment of the Purchase Price shall be in lawful money of the
United States in cash or by certified or official bank check payable to the
order of the Company.

          1.2 EFFECTIVENESS. Each exercise of this Warrant shall be deemed to
have been effected immediately prior to the close of business on the day on
which this Warrant shall have been surrendered to the Company as provided in
Section 1.1 above. At such time, the person or persons in whose name or names
any certificates for Warrant Stock shall be issuable upon such exercise as
provided in Section 1.3 below shall be deemed to have become the holder or
holders of record of the warrant Stock represented by such certificates.

                                      1.

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          1.3 DELIVERY OF CERTIFICATE. As soon as practicable after the
exercise of this Warrant in full or in part, and in any event within ten (10)
days thereafter, the Company at its sole expense will cause to be issued in
the name of, and delivered to, the Holder, or, subject to the terms and
conditions hereof, as such Holder (upon payment by such Holder of any
applicable transfer taxes) may direct:

               (a) a certificate or certificates for the number of full
shares of Warrant Stock to which such Holder shall be entitled upon such
exercise plus, in lieu of any fractional share to which such Holder would
otherwise be entitled, cash in an amount determined pursuant to Section 3
hereof, and

               (b) in case such exercise is in part only, a new warrant or
warrants (dated the date hereof) of like tenor, calling in the aggregate on
the face or faces thereof for the number of shares of Warrant Stock (without
giving effect to any adjustment therein) equal to the number of such shares
called for on the face of this Warrant minus the number of such shares
purchased by the Holder upon such exercise as provided in Section 1.1 above.

     2. FRACTIONAL SHARES. The Company shall not be required upon the
exercise of this warrant to issue any fractional shares, but shall make an
adjustment therefor in cash on the basis of the fair market value of the
Warrant Stock as shall be reasonably determined by the Board of Directors of
the Company.

     3. ADJUSTMENTS. The number of shares of warrant Stock shall be subject
to the following adjustments as contained in this Section 3.

          3.1 SPECIAL DEFINITIONS. For purposes of this Section 3, the
following definitions shall apply:

               (a) "OPTION" shall mean rights, options or warrants to
subscribe for, purchase or otherwise acquire either Common Stock or
Convertible Securities (as defined below).

               (b) "ORIGINAL ISSUE DATE" shall mean the date on which a share
of the Company's Series A Convertible Preferred Stock, par value $.001 per
share (the "SERIES A CONVERTIBLE PREFERRED STOCK"), was first issued.

               (c) "CONVERTIBLE SECURITIES" shall mean any evidences of
indebtedness, shares (other than Common Stock and Series A Convertible
Preferred Stock) or other securities directly or indirectly convertible into
or exchangeable for Common Stock.

               (d) "ADDITIONAL SHARES OF COMMON STOCK" shall mean all shares
of Common Stock issued (or, pursuant to Section 3.3, deemed to be issued) by,
the Company after the Original Issue Date, other than the following
(collectively, "EXCLUDED SHARES"):

                    (i) shares of common Stock issued or issuable upon
conversion of shares of Series A Convertible Preferred Stock; or

                                      2.

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                    (ii) shares of Common Stock issued or issuable upon
conversion of shares of Series A Convertible Preferred Stock outstanding on
the Original Issue Date; or

                    (iii) shares of Common Stock issued or issuable to
officers, employees or directors of, or consultants to, the company pursuant
to a stock purchase or option plan or other employee stock bonus arrangement
(collectively, the "PLANS") approved by the Board of Directors; or

                    (iv) shares of Common Stock issuable pursuant to warrants
outstanding as of the first Original Issue Date (notwithstanding any
subsequent transfer of all or part of such warrants); or

                    (v) shares of Common Stock issued or issuable pursuant to
warrants issued in connection with the establishment of credit facilities for
the company (including, without limitation, in connection with equipment
leasing arrangements); or

                    (vi) shares of Common Stock issued in connection with
corporate partnering relationships or joint ventures approved by the Board of
Directors.

          3.2 NO ADJUSTMENT OF PURCHASE PRICE. No adjustment in the number of
shares of Warrant Stock into which a Warrant is convertible shall be made, by
adjustment in the Purchase Price in respect of the issuance of Additional
Shares of Common Stock or otherwise unless the consideration per share for an
Additional Share of Common Stock issued or deemed to be issued by the Company
is less than the Purchase Price in effect on the date of, and immediately
prior to, the issue of such Additional Shares of Common Stock.

          3.3 ISSUE OF SECURITIES DEEMED ISSUE OF ADDITIONAL SHARES OF COMMON
STOCK.

               (a) OPTIONS AND CONVERTIBLE SECURITIES. In the event the
Company at any time or from time to time after the Original Issue Date shall
issue any Options or Convertible Securities or shall fix a record date for
the determination of holders of any class of securities entitled to receive
any such Options or Convertible Securities, then the maximum number of shares
(as set forth in the instrument relating thereto without regard to any
provisions contained therein for a subsequent adjustment of such number) of
Common Stock issuable upon the exercise of such Options or, in the case of
Convertible Securities and Options therefor, the conversion or exchange of
such Convertible Securities, shall be deemed to be Additional Shares of
Common Stock issued as of the time of such issue or, in case such a record
date shall have been fixed, as of the close of business on such record date,
provided that Additional Shares of Common Stock shall not be deemed to have
been issued unless the consideration per share (determined pursuant to
Section 3.5 hereof) of such Additional Shares of Common Stock would be less
than the Purchase Price in effect on the date of and immediately prior to
such issue, or such record date, as the case may be, and provided further
that in any such case in which Additional Shares of Common Stock are deemed
to be issued:

                                      3.

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                    (i) no further adjustment in the Purchase Price shall be
made upon the subsequent issue of Convertible Securities or shares of Common
Stock upon the exercise of such Options or conversion or exchange of such
Convertible Securities;

                    (ii) if such options or Convertible Securities by their
terms provide, with the passage of time or otherwise, for any increase in the
consideration payable to the company, or decrease in the number of shares of
Carmon Stock issuable upon the exercise. conversion or exchange thereof, the
Purchase Price computed upon the original issue thereof (or upon the
occurrence of a record date with respect thereto), and any subsequent
adjustments based thereon, shall, upon any such increase or decrease becoming
effective, be recomputed to reflect such increase or decrease insofar as it
affects such options or the rights of conversion or exchange under such
Convertible Securities;

                    (iii) upon the expiration of any such options or any
rights of conversion or exchange under such Convertible Securities which
shall not have been exercised, the Purchase Price computed upon the original
issue thereof (or upon the occurrence of a record date with respect thereto),
and any subsequent adjustments based thereon, shall, upon such expiration, be
recomputed as if:

                         (1) in the case of Convertible Securities or Options
for Common Stock the only Additional Shares of Common Stock issued were the
shares of Common Stock, if any, actually issued upon the exercise of such
Options or the conversion or exchange of such Convertible Securities and the
consideration received therefor was the consideration actually received by
the Company for the issue of all such Options, whether or not exercised, plus
the consideration actually received by the Company upon such exercise, or for
the issue of all such Convertible Securities which were actually converted or
exchanged, plus the additional consideration, if any, actually received by
the Company upon such conversion or exchange; and

                         (2) in the case of Options for Convertible
Securities only the Convertible Securities, if any, actually issued upon the
exercise thereof were issued at the time of issue of such Options, and the
consideration received by the Company for the Additional Shares of Common
Stock deemed to have been then issued was the consideration actually received
by the Company for the issue of all such Options, whether or not exercised,
plus the consideration deemed to have been received by the company
(determined pursuant to Section 3.5) upon the issue of the Convertible
Securities with respect to which such Options were actually exercised;

                    (iv) no readjustment pursuant to clause (i) or (iii)
above shall have the effect of increasing the Purchase Price to an amount
which exceeds the lower of (x) the Purchase Price on the original adjustment
date, or (y) the Purchase Price that would have resulted from any issuance of
Additional Shares of Common Stock between the original adjustment date and
such readjustment date;

                    (v) in the case of any Options which expire by their
terms not more than 30 days after the date of issue thereof, no adjustment of
the Purchase Price shall be made until the expiration or exercise of all such
Options, whereupon such adjustment shall be made in the same manner provided
in clause (iii) above; and

                                      4.

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                    (vi) if such record date shall have been fixed and such
Options or Convertible Securities are not issued on the date fixed therefor,
the adjustment previously made in the Purchase Price which became effective
on such record date shall be cancelled as of the close of business on such
record date, and thereafter the Purchase Price shall be adjusted pursuant to
this Section 3.3 as of the actual date of their issuance.

               (b) STOCK DIVIDENDS, STOCK DISTRIBUTIONS AND SUBDIVISIONS. In
the event the Company at any time or from time to time after the Original
Issue Date shall declare or pay any dividend or make any other distribution
on the Common Stock payable in Common Stock or effect a subdivision of the
outstanding shares of Common Stock (by reclassification or otherwise than by
payment of a dividend in Common Stock), then and in any such event,
Additional Shares of Common Stock shall be deemed to have been issued:

                    (i) in the case of any such dividend or distribution,
immediately after the close of business on the record date for the
determination of holders of any class of securities entitled to receive such
dividend or distribution, or

                    (ii) in the case of any such subdivision, at the close of
business on the date immediately prior to the date upon which corporate
action becomes effective.

     If such record date shall have been fixed and no part of such dividend
shall have been paid on, the date fixed therefor, the adjustment previously
made for the Purchase Price which became effective on such record date shall
be cancelled as of the close of business on such record date, and thereafter
the Purchase Price shall be adjusted pursuant to this Section 3.3(b) as of
the time of actual payment of such dividend.

          3.4 ADJUSTMENT OF PURCHASE PRICE UPON ISSUANCE OF ADDITIONAL SHARES
OF COMMON STOCK.

               (a) In the event the Company shall issue Additional Shares of
Common Stock (including, without limitation, Additional Shares of Common
Stock deemed to be issued pursuant to Section 3.3 but excluding Additional
Shares of Common Stock deemed to be issued pursuant to Section 3.3(b), which
event is dealt with in Section 3.6 hereof), without consideration or for a
consideration per share less than the applicable Purchase Price in effect on
the date of and immediately prior to such issue, then and in such event, such
Purchase Price shall be reduced, concurrently with such issue, to a price
(calculated to the nearest cent) determined by multiplying such Purchase
Price by a fraction, the numerator of which shall be (i) the number of shares
of Common Stock outstanding immediately prior to such issue plus (ii) the
number of shares of Common Stock which the aggregate consideration received
or deemed to have been received by the Company for the total number of
Additional Shares of Common Stock so issued would purchase at such Purchase
Price, and the denominator of which shall be (i) the number of shares of
Common Stock outstanding immediately prior to such issue plus (ii) the number
of Additional Shares of Common Stock so issued or deemed to be issued.

               (b) For the purposes of Section 3.4(a) hereof, (i) all shares
of Common Stock issuable upon conversion of shares of Series A Convertible
Preferred Stock, and upon exercise of options or conversion or exchange of
Convertible Securities which are part of the

                                      5.

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Excluded Shares, outstanding immediately prior to any issue of Additional
Shares of Common Stock, or any event with respect to which Additional Shares
of Common Stock shall be deemed to be issued, shall be deemed to be
outstanding; and (ii) immediately after any Additional Shares of Common Stock
are deemed issued pursuant to Section 3.3, such Additional Shares of Common
Stock shall be deemed to be outstanding.

               (c) Notwithstanding anything to the contrary contained herein,
the applicable Purchase Price in effect at the time Additional Shares of
Common Stock are issued or deemed to be issued shall not be reduced pursuant
to Section 3.4(a) hereof at such time if the amount of such reduction would
be an amount less than $0.01, but any such amount shall be carried forward
and reduction with respect thereto made at the time of and together with any
subsequent reduction which, together with such amount and any other amount or
amounts so carried forward, shall aggregate $0.01 or more.

          3.5 DETERMINATION OF CONSIDERATION. For purposes of this Section 3,
the consideration received by the Company for the issue of any Additional
Shares of Common Stock shall be computed as follows;

               (a) CASH AND PROPERTY. Such consideration shall:

                    (i) insofar as it consists of cash, be computed at the
aggregate amounts of cash received by the company excluding amounts paid or
payable for accrued interest or accrued dividends;

                    (ii) insofar as it consists of property other than cash,
be computed at the fair market value thereof at the time of such issue, as
determined in good faith by the Board of Directors; and

                    (iii) in the event Additional Shares of Common Stock are
issued together with ocher shares or securities or other assets of the
Company for consideration which covers both, be the proportion of such
consideration so received, computed as provided in clauses (i) and (ii)
above, as determined in good faith by the Board of Directors.

               (b) OPTIONS AND CONVERTIBLE SECURITIES. The consideration per
share received by the company for Additional Shares of Common Stock deemed to
have been issued pursuant to Section 3.3(a), relating to Options and
Convertible Securities, shall be determined by dividing (i) the total amount,
if any, received or receivable by the company as consideration for the issue
of such Options or Convertible Securities, plus the minimum aggregate amount
of additional consideration (as set forth in the instruments relating
thereto, without regard to any provision contained therein for a subsequent
adjustment of such consideration) payable to the Company upon the exercise of
such Options or the conversion or exchange of such Convertible Securities or
in the case of options for Convertible Securities, the exercise of such
Options for Convertible Securities and the conversion or exchange of such
Convertible Securities, by (ii) the maximum number of shares of Common Stock
(as set forth in the instruments relating thereto, without regard to any
provision contained therein for a subsequent adjustment of such number)
issuable upon the exercise of such options or the conversion or exchange of
such Convertible Securities.

                                      6.

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          3.6 ADJUSTMENT FOR DIVIDENDS, DISTRIBUTIONS, SUBDIVISIONS,
COMBINATIONS OR CONSOLIDATIONS OF COMMON STOCK.

               (a) STOCK DIVIDENDS, DISTRIBUTIONS OR SUBDIVISIONS. In the
event the company shall issue Additional Shares of Common Stock pursuant to
Section 3.3(b) in a stock dividend, stock distribution or subdivision, the
Purchase Price in effect immediately prior to such stock dividend. Stock
distribution or subdivision shall, concurrently with the effectiveness of
such stock dividend, stock distribution or subdivision, be proportionately
decreased.

               (b) COMBINATIONS OR CONSOLIDATIONS. In the event the
outstanding shares of Common Stock shall be combined or consolidated, by
reclassification or otherwise, into a lesser number of shares of Common
Stock, the Purchase Price in effect immediately prior to such combination or
consolidation shall, concurrently with the effectiveness of such combination
or consolidation, be proportionately increased.

          3.7 NO IMPAIRMENT. The Company shall not, by amendment of its
Certificate of Incorporation or through any reorganization, transfer of
assets, consolidation, merger, dissolution, issue or sale of securities or
any other voluntary action, avoid or seek to avoid the observance or
performance of any of the terms to be observed or performed hereunder by the
Company but shall at all times in good faith assist in the carrying out of
all the provisions of this Section 3 and in the taking of all such action as
may be necessary or appropriate in order to protect the rights of the Holder
against impairment.

          3.8 CERTIFICATE OF ADJUSTMENT. When any adjustment is required to
be made in the Purchase Price, the Company shall promptly mail to the Holder
a certificate setting forth the Purchase Price after such adjustment and
setting forth a brief statement of the facts requiring such adjustment. Such
certificate shall also set forth the kind and amount of stock or other
securities or property into which this Warrant shall be exercisable following
the occurrence of any of the events specified in this Section 3.

     4. COMPLIANCE WITH SECURITIES ACT.

          4.1 UNREGISTERED SECURITIES. The Holder acknowledges that this
Warrant and the Warrant Stock have not been registered under the Securities
Act of 1933, as amended, and the rules and regulations thereunder, or any
successor legislation (the "SECURITIES ACT"), and agrees not to sell, pledge,
distribute, offer for sale, transfer or otherwise dispose of this Warrant or
any Warrant Stock in the absence of (i) an effective registration statement
under the Securities Act covering this Warrant or such warrant Stock and
registration or qualification of this Warrant or such Warrant Stock under any
applicable "blue sky" or state securities law then in effect, or (ii) an
opinion of counsel, satisfactory to the Company, that such registration and
qualification are not required. The Company may delay issuance of the Warrant
Stock until completion of any action or obtaining of any consent, which the
Company deems necessary under any applicable law (including without
limitation state securities or "blue sky" laws).

          4.2 INVESTMENT LETTER. Without limiting the generality of Section
4.1, unless the offer and sale of any shares of Warrant Stock shall have been
effectively registered under

                                      7.

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the Securities Act, the Company shall be under no obligation to issue the
Warrant Stock unless and until the Holder shall have executed an investment
letter in form and substance satisfactory to the Company, including a
warranty at the time of such exercise that the Holder is acquiring such
shares for its own account, for investment and not with a view to, or for
sale in connection with, the distribution of any such shares.

          4.3 LEGEND. Certificates delivered to the Holder pursuant to
Section 4.3 shall bear the following legend or a legend in substantially
similar form:

          "The shares represented by this certificate have been
          taken for investment and they may not be sold or
          otherwise transferred by any person, including a pledgee,
          in the absence of an effective registration statement
          for the shares under the Securities Act of 1933, as
          amended, and applicable state securities laws or an
          opinion of counsel, satisfactory to the Company, that
          an exemption from registration is then available."

     5. LIQUIDATING DIVIDENDS. If the Company pays a dividend or makes a
distribution on the Common Stock payable other than in cash out of earnings
or earned surplus (determined in accordance with generally accepted
accounting principles) except for a stock dividend payable in shares of
Common Stock (a "LIQUIDATING DIVIDEND"), then the Company will pay or
distribute to the Holder, upon the exercise hereof, in addition to the
Warrant Stock issuable upon such exercise, the Liquidating Dividend which
would have been paid to such Holder if it had been the owner of record of
such shares of Warrant Stock immediately prior to the date on which a record
is taken for such Liquidating Dividend or, if no record is taken, the date as
of which the record holders of Common Stock entitled to such dividends or
distribution are to be determined.

     6. NOTICES OF RECORD DATE. In case:

               (a) the Company shall take a record of the holders of Common
Stock (or other stock or securities at the time deliverable upon the exercise
of this warrant) for the purpose of entitling or enabling them to receive any
dividend or other distribution (other than a dividend payable solely in
Common Stock or out of funds legally available therefor), or to receive any
right to subscribe for or purchase any shares of stock of any class or any
other securities, or to receive any other right, or

               (b) of any capital reorganization of the Company, any
reclassification of the capital stock of the Company, any consolidation or
merger of the Company with or into another corporation (other than a
consolidation or merger in which the Company is the surviving entity or of
which the sole purpose is to change the state of incorporation of the
Company), or any transfer of all or substantially all of the assets of the
Company, or

               (c) of the voluntary or involuntary dissolution, liquidation
or winding-up of the Company, then, and in each such case, the Company will
mail or cause to be mailed to the Holder a notice specifying, as the case may
be, (i) the date on which a record is to be taken for the purpose of such
dividend, distribution or right, and stating the amount and character of such
dividend, distribution or right, or (ii) the effective date on which such
reorganization,

                                      8.

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reclassification. consolidation, merger, transfer, dissolution, liquidation
or winding-up is to take place, and the time, if any is to be fixed, as of
which the holders of record of Common Stock (or such other stock or
securities at the time deliverable upon the exercise of this Warrant) shall
be entitled to exchange their shares of Common Stock (or such other stock or
securities) for securities or other property deliverable upon such
reorganization, reclassification, consolidation, merger, transfer,
dissolution, liquidation or winding-up. Such notice shall be mailed at least
ten (10) days prior to the record date or effective date for the event
specified in such notice; provided, however, that the failure to so mail such
notice shall not affect the legality or validity of any such action.

     7. RESERVATION OF STOCK. The Company will at all times reserve and keep
available, solely for issuance and delivery upon the exercise of this
Warrant, such shares of Warrant Stock and other stock, securities and
property, as from time to time shall be issuable upon the exercise of this
warrant.

     8. REPLACEMENT OF WARRANTS. Upon receipt of evidence reasonably
satisfactory to the Company of the loss, theft, destruction or mutilation of
this Warrant and (in the case of loss, theft or destruction) upon delivery of
an indemnity agreement (with surety if reasonably required) in an amount
reasonably satisfactory to the Company, or (in the case of mutilation) upon
surrender and cancellation of this Warrant, the Company will issue, in lieu
thereof, a new Warrant of like tenor.

     9. TERMINATION UPON CERTAIN EVENTS. In the event of (a) a sale of
substantially all the assets of the Company to, or (b) a merger or
consolidation of the Company with or into, any other entity (other than (i) a
merger in which the stockholders of the Company immediately prior to the
transaction possess more than 50% of the voting securities of the surviving
entity (or parent, if any) immediately after the transaction, (ii) a merger
the sole purpose of which is to change the state of incorporation of the
Company) or (c) a dissolution or the adoption of a plan of liquidation of the
Company, this Warrant shall terminate on the effective date of such sale,
merger, consolidation, dissolution or adoption (the "EFFECTIVE DATE") and
become null and void; provided, however, that if this Warrant shall not have
otherwise terminated or expired, the Holder shall have the right until 5:00
p.m. Eastern standard time on the day immediately prior to the Effective Date
to exercise its rights hereunder to the extent not previously exercised.

     10. TRANSFERS.

          10.1 TRANSFERABILITY. This Warrant shall not be transferable by the
Holder and shall be exercisable only by the Holder. Without the prior written
consent of the Company, the Warrant shall not be assigned, pledged or
hypothecated in any way (whether by operation of law or otherwise) and shall
not be subject to execution, attachment or similar process. Any attempted
transfer, assignment, pledge, hypothecation or other disposition of the
Warrant or of any rights granted hereunder contrary to the provisions of this
Section 10.1, or the levy of any attachment or similar process upon the
warrant or such rights, shall be null and void.

          10.2 WARRANT REGISTER. The Company will maintain a register (the
"Warrant Register") containing the names and addresses of the Holders of this
Warrant. Any Holder may

                                      9.

<PAGE>

change its, his or her address as shown on the Warrant Register by written
notice to the Company requesting such change.

          10.3 WARRANT AGENT. The Company may, by written notice to the
Holder, appoint an agent for the purpose of issuing Warrant Stock (or such
other securities at the time deliverable upon the exercise of the Warrant),
exchanging or replacing the Warrant and maintaining the Warrant Register, and
thereafter any such issuance, exchange or replacement shall be made by such
agent.

          10.4 RECOGNITION OF OWNERSHIP. Until any transfer of this Warrant
is made in the Warrant Register, the Company may treat the Holder as the
absolute owner hereof for all purposes; provided, however, that if and when
this Warrant is properly assigned in blank, the Company may (but shall not be
obligated to) treat the bearer hereof as the absolute owner hereof for all
purposes, notwithstanding any notice to the contrary.

     11. NO RIGHTS AS STOCKHOLDER. Until the exercise of this warrant, the
Holder shall not have or exercise any rights by virtue hereof as a
stockholder of the Company.

     12. NOTICES. All notices, requests and other communications hereunder
shall be in writing, shall be either (i) delivered by hand, (ii) made by
telex, telecopy or facsimile transmission, (iii) sent by overnight courier,
or (iv) sent by certified or registered mail, postage prepaid, return receipt
requested. In the case of notices from the Company to the Holder, they shall
be sent to the address furnished to the Company in writing by the last Holder
who shall have furnished an address to the Company in writing. All notices
from the Holder to the Company shall be delivered to the Company at its
offices at 246 Commonwealth Avenue, Boston, Massachusetts 02116, or such
other address as the Company shall so notify the Holder. All notices,
requests and other communications hereunder shall be deemed to have been
given (i) by hand, at the time of the delivery thereof to the receiving party
at the address of such party described above, (ii) if made by telex, telecopy
or facsimile transmission, at the time that receipt thereof has been
acknowledged by electronic confirmation or otherwise, (iii) if sent by
overnight courier, on the next business day following the day such notices is
delivered to the courier service, or (iv) if sent by certified or registered
mail, on the fifth business day following the day such mailing is made.

     13. WAIVERS AND MODIFICATIONS. Any term or provision of this Warrant may
be waived only by written document executed by the party entitled to the
benefits of such terms or provisions. The terms and provisions of this
Warrant may be modified or amended only by written agreement executed by the
parties hereto.

     14. HEADINGS. The headings in this Warrant are for convenience of
reference only and shall in no way modify or affect the meaning or
construction of any of the terms or provisions of this Warrant.

     15. GOVERNING LAW. This Warrant will be governed by and construed in
accordance with and governed by the laws of the Commonwealth of
Massachusetts, without giving effect to the conflict of law principles
thereof.

                                      10.

<PAGE>

     This warrant certificate has been executed by a duly authorized officer
of the Company and is intended to be treated as an instrument under seal.

                                      EXELIXIS PHARMACEUTICALS, INC.

                                      By: /s/ Sherry Reynolds
                                         -------------------------------------
                                          Sherry Reynolds
                                          President and Chief Operating Officer

                                      11.

<PAGE>

                                    EXHIBIT A

                                  PURCHASE FORM

To:      Exelixis Pharmaceuticals, Inc.
         246 Commonwealth Avenue
         Boston, MA 02116

Dated:
      --------------------------

     The undersigned, pursuant to the provisions set forth in the attached
Warrant (No. W-1), hereby irrevocably elects to purchase shares of the Common
Stock, $.001 par value per share (the "COMMON STOCK"), of Exelixis
Pharmaceuticals, Inc. (the "COMPANY") covered by such Warrant and herewith makes
payment of $__________, representing the full purchase price for such shares at
the price per share provided for in such Warrant.

     The undersigned is aware that the Common Stock has not been registered
under the Securities Act of 1933, as amended (the "SECURITIES ACT") or any state
securities laws. The undersigned understands that reliance by the Company on
exemptions under the Securities Act is predicated in part upon the truth and
accuracy of the statements of the undersigned in this Purchase Form.

     The undersigned represents and warrants that (1) it has been furnished with
all information which it deems necessary to evaluate the merits and risks of the
purchase of the Common stock; (2) it has had the opportunity to ask questions
concerning the Common Stock and the Company and all questions posed have been
answered to its satisfaction; (3) it has been given the opportunity to obtain
any additional information it deems necessary to verify the accuracy of any
information obtained concerning the Common Stock and the Company; and (4) it has
such knowledge and experience in financial and business matters that it is able
to evaluate the merits and risks of purchasing the Common Stock and to make an
informed investment decision relating thereto.

     The undersigned hereby represents and warrants that it is purchasing the
Common Stock for its own account for investment and not with a view to the sale
or distribution of all or any part of the Common Stock.

     The undersigned understands that because the Common Stock has not been
registered under the Securities Act, it must continue to bear the economic risk
of the investment for an indefinite period of time and the Common Stock cannot
be sold unless it is subsequently registered under applicable federal and state
securities laws or an exemption from such registration is available.

     The undersigned agrees that it will in no event sell or distribute or
otherwise dispose of all or any part of the Common Stock unless (1) there is an
effective registration statement under the Securities Act and applicable state
securities laws covering any such transaction involving the Common Stock or (2)
the Company receives an opinion satisfactory to the company of the undersigned's
legal counsel stating that such transaction is exempt from registration. The

                                      1.

<PAGE>

undersigned consents to the placing of a legend on its certificate for the
Common Stock stating that the Common Stock has not been registered and
setting forth the restriction on transfer contemplated hereby and to the
placing of a stop transfer order on the books of the Company and with any
transfer agents against the Common Stock until the Common Stock may be
legally resold or distributed without restriction.

     The undersigned understands the restrictions on the right to transfer or
otherwise dispose of the Common Stock set forth in the Warrant, which the
undersigned has carefully reviewed. The undersigned consents to the placing
of a legend on its certificate for the Common Stock referring to such
restrictions and the placing of stop transfer orders until the Common Stock
may be transferred in accordance with the terms of such restrictions.

     The undersigned understands that at the present time Rule 144 of the
Securities and Exchange Commission (the "COMMISSION") is not available for
the resale or distribution of the Common Stock. The undersigned understands
that the Company has no obligation to the undersigned to register the common
Stock with the Commission and has not represented that it will register the
Common Stock.

     The undersigned has considered the federal and state income tax
implications of the exercise of the warrant and the purchase and subsequent
sale of the Common Stock.

                                    Holder:
                                           -----------------------------------

                                    Dated:
                                          ------------------------------------

                                      2.<PAGE>

                                                                    Exhibit 4.5

     THIS WARRANT HAS NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF
    1933, AS AMENDED (THE "1933 ACT"), OR ANY APPLICABLE STATE SECURITIES
      LAWS, AND MAY NOT BE SOLD OR TRANSFERRED UNLESS SUCH SALE OR
     TRANSFER IS IN ACCORDANCE WITH THE REGISTRATION REQUIREMENTS OF
     SUCH ACT AND APPLICABLE LAWS OR SOME OTHER EXEMPTION FROM THE
      REGISTRATION REQUIREMENTS OF SUCH ACT AND APPLICABLE LAWS IS
                    AVAILABLE WITH RESPECT THERETO.

                            EXELIXIS, INC.

                         COMMON STOCK WARRANT

Warrant No. __________

     FOR VALUE RECEIVED, Exelixis, Inc., a Delaware corporation (the "Company"),
with its principal office at 260 Littlefield Avenue, South San Francisco, CA
94080, hereby certifies that Bristow Investments, L.P., a California limited
partnership (the "Holder") is entitled, upon surrender of this Warrant with the
notice of exercise annexed hereto duly executed at the principal office of the
Company, to purchase from the Company 6,000 shares of common stock of the
Company, subject to adjustment as provided in Section 4. Such shares shall be
fully paid and nonassessable shares of Common Stock, $.001 par value, of the
Company (the "Common Stock") purchased at a price per share of Three Dollars
($3.00) (the "Purchase Price"), subject to the provisions set forth herein.
Until such time as this Warrant is exercised in full or expires, the Purchase
Price and the securities issuable upon exercise of this Warrant are subject to
adjustment as hereinafter provided. The person or persons on whose name or names
any certificate representing shares of Common Stock is issued hereunder shall be
deemed to have become Holder of record of the shares represented thereby as at
the close of business on the date this Warrant is exercised with respect to such
shares, whether or not the transfer books of the Company shall be closed. The
shares of Common Stock deliverable upon such exercise, as adjusted from time to
time, are hereinafter sometimes referred to as "Warrant Shares."

     1. TERM. The purchase right represented by this Warrant is exercisable, in
whole or in part, at any time and from time to time from the date of grant
through the date which is five (5) years after the closing of the Company's
initial public offering of its Common Stock effected pursuant to a Registration
Statement on Form S-1 (or its successor) filed under the Securities Act of 1933,
as amended (the "Act").

     2. METHOD OF EXERCISE; PAYMENT; ISSUANCE OF NEW WARRANT.

        2.1 General. Subject to Section 1 hereof, the purchase right represented
by this Warrant may be exercised by Holder hereof, in whole or in part and from
time to time, by the surrender of this Warrant (with the notice of exercise form
attached hereto as Exhibit A duly executed) at the principal office of the
Company and by the payment to the Company, by cash, check or wire transfer, of
an amount equal to the then applicable Purchase Price multiplied by

<PAGE>

the number of Warrant Shares then being purchased. The person or persons in
whose name(s) any certificate(s) representing shares of Common Stock shall be
issuable upon exercise of this Warrant shall be deemed to have become Holder(s)
of record of, and shall be treated for all purposes as the record Holder(s) of,
the shares represented thereby (and such shares shall be deemed to have been
issued) immediately prior to the close of business on the date or dates upon
which this Warrant is exercised. In the event of any exercise of the rights
represented by this Warrant, certificates for the shares of stock so purchased
shall be delivered to Holder hereof as soon as possible and in any event within
thirty days after such exercise and, unless this Warrant has been fully
exercised or expired, a new Warrant of like tenor representing the portion of
the Warrant Shares, if any, with respect to which this Warrant shall not then
have been exercised shall also be issued to Holder hereof as soon as possible
and in any event within such thirty-day period.

        2.2 NET ISSUE EXERCISE. Notwithstanding any provisions herein to the
contrary, if the fair market value of one share of the Company's Common Stock is
greater than the Purchase Price (at the date of calculation as set forth below),
in lieu of exercising this Warrant for cash, Holder may elect to receive Warrant
Shares equal to the value (as determined below) of this Warrant (or the portion
thereof being canceled) by surrender of this Warrant (with the notice of
exercise form attached hereto as Exhibit A duly executed) in which event the
Company shall issue to Holder a number of Warrant Shares computed using the
following formula:

            X = Y (A-B)
                -------
                   A

     Where X = the number of shares of Warrant Shares to be issued to Holder

            Y = the number of Warrant Shares purchasable under the Warrant or,
            if only a portion of the Warrant is being exercised, the portion of
            the Warrant being canceled (at the date of such calculation)

            A = the fair market value of one share of the Company's Common Stock
            (at the date of such calculation)

            B = the Purchase Price (as adjusted to the date of such calculation)

        For purposes of the above calculation, fair market value of one share of
Common Stock shall be determined as follows: (i) if the class of stock of which
the Warrant Shares are a part is listed on a national stock exchange, on the
NASDAQ National Market System or on any other over-the-counter market, then such
fair market value shall be the closing price per share reported for such class
on such national stock exchange or on the NASDAQ National Market System, or the
average of the final "bid" and "asked" prices reported on such over-the-counter
market, as applicable, at the close of business on the date of calculation, as
reported in the Wall Street Journal; and (ii) if the class of stock of which the
Warrant Shares are a part is not listed on any national stock exchange, on the
NASDAQ National Market System or on any other over-the-

                                       2

<PAGE>

counter market, then the Board of Directors of the Company shall determine such
fair market value as of the date of calculation in its reasonable good faith
judgment, and shall (upon written request by Holder) advise Holder of such
determination prior to any decision by the registered Holder to exercise its
purchase rights under this Warrant.

     3. STOCK FULLY PAID; RESERVATION OF SHARES. All Warrant Shares that may be
issued upon the exercise of the rights represented by this Warrant will, upon
issuance pursuant to the terms and conditions herein, be fully paid and
nonassessable, and free from all taxes, liens and charges with respect to the
issue thereof. During the period within which the rights represented by this
Warrant may be exercised, the Company will at all times have authorized, and
reserved for the purpose of the issue upon exercise of the purchase rights
evidenced by this Warrant, a sufficient number of shares of its Common Stock to
provide for the exercise of the rights represented by this Warrant. The Company
will take all such actions as may be necessary to assure that such shares of
Common Stock may be issued as provided herein without violation of any
applicable law or regulation, or of any requirements of any domestic securities
exchange upon which the Common Stock may be listed; provided, however, that the
Company shall not be required to effect a registration under the Act or state
securities laws with respect to such exercise. The covenant set forth in the
immediately preceding sentence is based in part on the representations made by
Holder in Section 7 and assumes no change in currently applicable law that would
make such actions impracticable.

     4. ADJUSTMENT OF PURCHASE PRICE AND NUMBER OF SHARES. The number and kind
of securities purchasable upon the exercise of this Warrant and the Purchase
Price shall be subject to adjustment from time to time upon the occurrence of
certain events, as follows:

        4.1 RECLASSIFICATION OR MERGER. In case of any reclassification, change
or conversion of securities of the class issuable upon exercise of this Warrant
(other than a change in par value, or from par value to no par value, or from no
par value to par value, or as a result of a subdivision or combination), or in
case of any merger of the Company with or into another corporation (other than a
merger with another corporation in which the Company is the acquiring and the
surviving corporation and which does not result in any reclassification or
change of outstanding securities issuable upon exercise of this Warrant), or in
case of any sale of all or substantially all of the assets of the Company, the
Company, or such successor or purchasing corporation, as the case may be, shall
duly execute and deliver to Holder a new Warrant (in form and substance
satisfactory to Holder), so that Holder shall have the right to receive, at a
total purchase price not to exceed that payable upon the exercise of the
unexercised portion of this Warrant, and in lieu of the shares of Common Stock
theretofore issuable upon exercise of this Warrant, the kind and amount of
shares of stock, other securities, money and property receivable upon such
reclassification, change or merger by a Holder of the number of shares of Common
Stock then purchasable under this Warrant. Such new Warrant shall provide for
adjustments that shall be as nearly equivalent as may be practicable to the
adjustments provided for in this Section 4. The provisions of this Section 4.1
shall similarly apply to successive reclassifications, changes, mergers and
transfers.

        4.2 SUBDIVISION OR COMBINATION OF SHARES. If the Company at any time
while this Warrant remains outstanding and unexpired shall subdivide or combine
its outstanding shares of Common Stock, the Purchase Price shall be
proportionately decreased in the case of a

                                       3

<PAGE>

subdivision or increased in the case of a combination, effective at the close of
business on the date the subdivision or combination becomes effective.

        4.3 STOCK DIVIDENDS AND OTHER DISTRIBUTIONS. If the Company at any time
while this Warrant is outstanding and unexpired shall (i) pay a dividend with
respect to Common Stock payable in Common Stock, or (ii) make any other
distribution with respect to Common Stock (except any distribution specifically
provided for in the foregoing subparagraphs (a) and (b)) of Common Stock, then
the Purchase Price shall be adjusted, from and after the date of determination
of shareholders entitled to receive such dividend or distribution, to that price
determined by multiplying the Purchase Price in effect immediately prior to such
date of determination by a fraction (i) the numerator of which shall be the
total number of shares of Common Stock outstanding immediately prior to such
dividend or distribution, and (ii) the denominator of which shall be the total
number of shares of Common Stock outstanding immediately after such dividend or
distribution.

        4.4 ADJUSTMENT OF NUMBER OF SHARES. Upon each adjustment in the Purchase
Price, the number of Warrant Shares purchasable hereunder shall be adjusted, to
the nearest whole share, to the product obtained by multiplying the number of
Warrant Shares purchasable immediately prior to such adjustment in the Purchase
Price by a fraction, the numerator of which shall be the Purchase Price
immediately prior to such adjustment and the denominator of which shall be the
Purchase Price immediately thereafter.

     5. NOTICE OF CERTAIN EVENTS

        5.1 NOTICE OF ADJUSTMENTS. Whenever the Purchase Price or the number of
Warrant Shares purchasable hereunder shall be adjusted pursuant to Section 4
hereof, the Company shall make a certificate signed by its chief financial
officer setting forth, in reasonable detail, the event requiring the adjustment,
the amount of the adjustment, the method by which such adjustment was
calculated, and the Purchase Price and the number of Warrant Shares purchasable
hereunder after giving effect to such adjustment, shall be mailed (without
regard to Section 8.2 hereof, by first class mail, postage prepaid) to Holder.

        5.2 OTHER NOTICES. If at any time:

            (a) the Company shall declare any cash dividend upon its Common
Stock;

            (b) the Company shall declare any dividend upon its Common Stock
payable in stock or make any special dividend or other distribution to the
holders of its Common Stock;

            (c) the Company shall offer for subscription pro rata to all holders
of its Common Stock any additional shares of stock of any class or other rights;

            (d) there shall be any capital reorganization or reclassification of
the capital stock of the Company, or consolidation or merger of the Company
with, or sale of all or substantially all of its assets to, another corporation
or other entity;

                                       4

<PAGE>

            (e) there shall be a voluntary or involuntary dissolution,
liquidation or winding-up of the Company; or

            (f) there shall be an initial public offering of Company securities;

            then, in any one or more of said cases, the Company shall give, by
first class mail, postage prepaid, addressed to Holder at the address of Holder
as shown on the books of the Company, (1) at least ten (10) days' prior written
notice of the date on which the books of the Company shall close or a record
shall be taken for such dividend, distribution, or subscription rights or for
determining rights to vote in respect of any such reorganization,
reclassification, consolidation, merger, sale, dissolution, liquidation,
winding-up or public offering, and (2) in the case of any such event, at least
ten (10) days' prior written notice of the date when the same shall take place,
provided, however, Holder shall make a best efforts attempt to respond to such
notice as early as possible after the receipt thereof. Any notice given in
accordance with the foregoing clause (1) shall also specify, in the case of any
such dividend, distribution or subscription rights, the date on which the
holders of Common Stock shall be entitled thereto. Any notice given in
accordance with the foregoing clause (2) shall also specify the date on which
the holders of Common Stock shall be entitled to exchange their Common Stock for
securities or other property deliverable upon such reorganization,
reclassification, consolidation, merger, sale, dissolution, liquidation,
winding-up, conversion or public offering, as the case may be.

     6. FRACTIONAL INTEREST. In no event shall any fractional share of Common
Stock be issued upon any exercise of this Warrant. If, upon exercise of this
Warrant as an entirety, Holder would, except as provided in this Section 6, be
entitled to receive a fractional share of Common Stock, then the Company shall
issue the next higher number of full shares of Common Stock, issuing a full
share with respect to such fractional share.

     7. COMPLIANCE WITH SECURITIES ACT; DISPOSITION OF WARRANT OR SHARES OF
COMMON STOCK.

        7.1 COMPLIANCE WITH SECURITIES ACT. Holder, by acceptance hereof, agrees
that this Warrant, and the shares of Common Stock to be issued upon exercise
hereof are being acquired for investment and that Holder will not offer, sell or
otherwise dispose of this Warrant, or any shares of Common Stock to be issued
upon exercise hereof except under circumstances which will not result in a
violation of the Act. Upon exercise of this Warrant, unless the Warrant Shares
being acquired are registered under the Act or an exemption from such
registration is available, Holder shall confirm in writing that the shares of
Common Stock so purchased are being acquired for investment and not with a view
toward distribution or resale. This Warrant and all shares of Common Stock
issued upon exercise of this Warrant (unless registered under the Act) shall be
stamped or imprinted with a legend in substantially the following form:

     "THE SECURITIES EVIDENCED HEREBY HAVE NOT BEEN REGISTERED UNDER THE
     SECURITIES ACT OF 1933, AS AMENDED, OR ANY STATE SECURITIES LAWS. NO SALE
     OR DISPOSITION MAY BE EFFECTED WITHOUT (i) EFFECTIVE REGISTRATION
     STATEMENTS RELATED THERETO, (ii) AN OPINION OF COUNSEL FOR HOLDER,
     REASONABLY SATISFACTORY TO THE COMPANY, THAT SUCH

                                       5

<PAGE>

     REGISTRATIONS ARE NOT REQUIRED, (iii) RECEIPT OF NO-ACTION LETTERS FROM THE
     APPROPRIATE GOVERNMENTAL AUTHORITIES, OR (iv) OTHERWISE COMPLYING WITH THE
     PROVISIONS OF SECTION 7 OF THE WARRANT UNDER WHICH THESE SECURITIES WERE
     ISSUED, DIRECTLY OR INDIRECTLY."

        7.2 REPRESENTATIONS OF HOLDER. In addition, in connection with the
issuance of this Warrant, Holder specifically represents to the Company by
acceptance of this Warrant as follows:

            (a) Holder is aware of the Company's business affairs and financial
condition, and has acquired information about the Company sufficient to reach an
informed and knowledgeable decision to acquire this Warrant. Holder is acquiring
this Warrant for its own account for investment purposes only and not with a
view to, or for the resale in connection with, any "distribution" thereof for
purposes of the Act.

            (b) Holder understands that this Warrant has not been registered
under the Act in reliance upon a specific exemption therefrom, which exemption
depends upon, among other things, the bona fide nature of Holder's investment
intent as expressed herein. In this connection, Holder understands that, in the
view of the SEC, the statutory basis for such exemption may be unavailable if
Holder's representation was predicated solely upon a present intention to hold
the Warrant for the minimum capital gains period specified under tax statutes,
for a deferred sale, for or until an increase or decrease in the market price of
the Warrant, or for a period of one year or any other fixed period in the
future.

            (c) Holder further understands that this Warrant must be held
indefinitely unless subsequently registered under the Act and any applicable
state securities laws, or unless exemptions from registration are otherwise
available. Moreover, Holder understands that the Company is under no obligation
to register this Warrant.

            (d) Holder is aware of the provisions of Rule 144 and 144A,
promulgated under the Act, which, in substance, permit limited public resale of
"restricted securities" acquired, directly or indirectly, from the issuer
thereof (or from an affiliate of such issuer), in a non-public offering subject
to the satisfaction of certain conditions, if applicable, including, among other
things: The availability of certain public information about the Company, the
resale occurring not less than two years after the party has purchased and paid
for the securities to be sold; the sale being made through a broker in an
unsolicited "broker's transaction" or in transactions directly with a market
maker (as said term is defined under the Securities Exchange Act of 1934, as
amended) and the amount of securities being sold during any three-month period
not exceeding the specified limitations stated therein.

            (e) Holder further understands that at the time it wishes to sell
this Warrant there may be no public market upon which to make such a sale, and
that, even if such a public market then exists, the Company may not be
satisfying the current public information requirements of Rule 144 and 144A, and
that, in such event, Holder may be precluded from selling this Warrant under
Rule 144 and 144A even if the two-year minimum holding period had been
satisfied.

                                       6

<PAGE>

            (f) Holder further understands that in the event all of the
requirements of Rule 144 and 144A are not satisfied, registration under the Act,
compliance with Regulation A, or some other registration exemption will be
required; and that, notwithstanding the fact that Rule 144 and 144A are not
exclusive, the Staff of the SEC has expressed its opinion that persons proposing
to sell private placement securities other than in a registered offering and
otherwise than pursuant to Rule 144 and 144A will have a substantial burden of
proof in establishing that an exemption from registration is available for such
offers or sales, and that such persons and their respective brokers who
participate in such transactions do so at their own risk.

        7.3 DISPOSITION OF WARRANT OR SHARES. With respect to any offer, sale or
other disposition of this Warrant or any shares of Common Stock acquired
pursuant to the exercise of this Warrant prior to registration of such Warrant
or shares, Holder hereof and each subsequent Holder agrees to give written
notice to the Company prior thereto, describing briefly the manner thereof,
together with a written opinion of Holder's counsel, if reasonably requested by
the Company, to the effect that such offer, sale or other disposition may be
effected without registration or qualification (under the Act as then in effect
or any federal or state law then in effect) of this Warrant or such shares of
Common Stock and indicating whether or not under the Act certificates for this
Warrant or such shares of Common Stock to be sold or otherwise disposed of
require any restrictive legend as to applicable restrictions on transferability
in order to ensure compliance with such law. Promptly upon receiving such
written notice and reasonably satisfactory opinion, if so requested, the
Company, as promptly as practicable, shall notify Holder that Holder may sell or
otherwise dispose of this Warrant or such shares of Common Stock, all in
accordance with the terms of the notice delivered to the Company. If a
determination has been made pursuant to this Section 7.3 that the opinion of
counsel for Holder is not reasonably satisfactory to the Company, the Company
shall so notify Holder promptly after such determination has been made and shall
specify in detail the legal analysis supporting any such conclusion.
Notwithstanding the foregoing, this Warrant or such shares of Common Stock may,
as to such federal laws, be offered, sold or otherwise disposed of in accordance
with Rule 144 or 144A under the Act, provided that the Company shall have been
furnished with such information as the Company may reasonably request to provide
a reasonable assurance that the provisions of Rule 144 or 144A have been
satisfied. Each certificate representing this Warrant or the shares of Common
Stock thus transferred (except a transfer pursuant to Rule 144 or 144A) shall
bear a legend as to the applicable restrictions on transferability in order to
ensure compliance with such laws, unless in the aforesaid opinion of counsel for
Holder, such legend is not required in order to ensure compliance with such
laws. The Company may issue stop transfer instructions to its transfer agent in
connection with such restrictions.

        7.4 EXCEPTED TRANSFERS. Neither any restrictions of any legend described
in this Warrant nor the requirements of Section 7.3 above shall apply to any
transfer without any additional consideration of, or grant of a security
interest in, this Warrant or any part hereof (i) to a partner of Holder if
Holder is a partnership, (ii) by Holder to a partnership of which Holder is a
general partner, or (iii) to any affiliate of Holder if Holder is a corporation;
PROVIDED, HOWEVER, in any such transfer, the transferee shall on the Company's
request agree in writing to be bound by the terms of this Warrant as if an
original signatory hereto.

                                       7

<PAGE>

        7.5 RIGHTS AS SHAREHOLDERS; INFORMATION. Holder shall not be entitled to
vote or receive dividends or be deemed a holder of Common Stock or any other
securities of the Company which may at any time be issuable on the exercise
hereof for any purpose, nor shall anything contained herein be construed to
confer upon Holder, as such, any of the rights of a shareholder of the Company
or any right to vote for the election of directors or upon any matter submitted
to shareholders at any meeting thereof, or to receive notice of meetings, or to
receive dividends or subscription rights or otherwise until this Warrant shall
have been exercised and the Warrant Shares purchasable upon the exercise hereof
shall have become deliverable, as provided herein. Notwithstanding the
foregoing, the Company will transmit to Holder such information, documents and
reports as are generally distributed to holders of any class or series of the
securities of the Company concurrently with the distribution thereof to the
shareholders and will, upon written request by Holder to the Chief Financial
Officer of the Company from time to time (but not more often than twice in any
12-month period) provide to Holder copies of the following documents within a
reasonable time after such request (but in all events only to the extent that,
and no sooner than the time that, such documents have been made available to the
Company's stockholders ): (i) the Company's most recent audited annual financial
statements or, if audited statements are not available, then the Company's
unaudited annual financial statements as of the end of the Company's most
recently ended fiscal year and (ii) unaudited quarterly financial statements for
each quarter of the Company's fiscal year since the date of the annual financial
statements delivered pursuant to clause (i) above. Notwithstanding the preceding
sentence, during any period in which the Company has outstanding a class of
publicly-traded securities or is for any reason a reporting company under the
Securities Exchange Act of 1934, it shall be sufficient compliance to provide
copies of its most recent Form 10-K and annual report, any Form 10-Qs and/or
8-Ks filed by the Company with the SEC since the date of such Form 10-K, and any
proxy statements.

        7.6 MARKET STANDOFF. Holder, by acceptance hereof, agrees that Holder
will not, without the prior written consent of the lead underwriter of the
initial public offering of the Common Stock of the Company pursuant to a Public
Offering, directly or indirectly offer to sell, contract to sell (including,
without limitation, any short sale), grant any option for the sale of, acquire
any option to dispose of, or otherwise dispose of any Warrant Shares for a
period of 180 days following the day on which the registration statement filed
on behalf of the Company in connection with the Public Offering shall become
effective by order of the SEC.

     8. MISCELLANEOUS

        8.1 MODIFICATION AND WAIVER. This Warrant and any provision hereof may
be changed, waived, discharged or terminated only by an instrument in writing
signed by the party against which enforcement of the same is sought.

        8.2 NOTICES. Any notice, request, communication or other document
required or permitted to be given or delivered to Holder hereof or the Company
shall be delivered, or shall be sent by certified or registered mail, postage
prepaid, to Holder at its address as shown on the books of the Company or to the
Company at the address indicated therefor on the signature page of this Warrant.

                                       8

<PAGE>

        8.3 BINDING EFFECT ON SUCCESSORS. This Warrant shall be binding upon any
corporation succeeding the Company by merger, consolidation or acquisition of
all or substantially all of the Company's assets, and all of the obligations of
the Company relating to the Common Stock issuable upon the exercise or
conversion of this Warrant shall survive the exercise, conversion and
termination of this Warrant and all of the covenants and agreements of the
Company shall inure to the benefit of the successors and assigns of Holder
hereof. The Company will, at the time of the exercise or conversion of this
Warrant, in whole or in part, upon request of Holder hereof but at the Company's
expense, acknowledge in writing its continuing obligation to Holder hereof in
respect of any rights (including, without limitation, any right to registration
of the shares of Registrable Securities) to which Holder hereof shall continue
to be entitled after such exercise or conversion in accordance with this
Warrant; PROVIDED, that the failure of Holder hereof to make any such request
shall not affect the continuing obligation of the Company to Holder hereof in
respect of such rights.

        8.4 LOST WARRANTS OR STOCK CERTIFICATES. The Company covenants to Holder
hereof that, upon receipt of evidence reasonably satisfactory to the Company
(such as an affidavit of Holder) of the loss, theft, destruction or mutilation
of this Warrant or any stock certificate and, in the case of any such loss,
theft or destruction, upon receipt of an indemnity reasonably satisfactory to
the Company, or in the case of any such mutilation upon surrender and
cancellation of such Warrant or stock certificate, the Company will make and
deliver a new Warrant or stock certificate, of like tenor, in lieu of the lost,
stolen, destroyed or mutilated Warrant or stock certificate.

        8.5 DESCRIPTIVE HEADINGS. The descriptive headings of the several
paragraphs of this Warrant are inserted for convenience only and do not
constitute a part of this Warrant.

        8.6 GOVERNING LAW. This Warrant shall be construed and enforced in
accordance with, and the rights of the parties shall be governed by, the laws of
the State of California.

        8.7 SURVIVAL OF REPRESENTATIONS, WARRANTIES AND AGREEMENTS. All
representations and warranties of the Company and Holder hereof contained herein
shall survive the date of grant, the exercise or conversion of this Warrant (or
any part hereof) or the termination or expiration of rights hereunder. All
agreements of the Company and Holder hereof contained herein shall survive
indefinitely until, by their respective terms, they are no longer operative.

        8.8 REMEDIES. In case any one or more of the covenants and agreements
contained in this Warrant shall have been breached, Holder (in the case of a
breach by the Company), or the Company (in the case of a breach by Holder), may
proceed to protect and enforce their or its rights either by suit in equity
and/or by action at law, including, but not limited to, an action for damages as
a result of any such breach and/or an action for specific performance of any
such covenant or agreement contained in this Warrant.

        8.9 ACCEPTANCE. Receipt of this Warrant by Holder hereof shall
constitute acceptance of and agreement to the foregoing terms and conditions.

                                       9

<PAGE>

        8.10 NO IMPAIRMENT OF RIGHTS. The Company will not, by amendment of its
Certificate of Incorporation or through any other means, avoid or seek to avoid
the observance or performance of any of the terms of this Warrant, but will at
all times in good faith assist in the carrying out of all such terms and in the
taking of all such action as may be necessary or appropriate in order to protect
the rights of Holder against impairment.

        8.11 ENTIRE AGREEMENT. This Warrant constitutes the entire agreement
between the parties pertaining to the subject matter herein and supersedes all
prior and contemporaneous agreements, representation and undertakings of the
parties.

        8.12 ATTORNEYS' FEES. In any litigation, arbitration or other legal
proceeding between the Company and Holder relating to or arising out of this
Warrant, the prevailing party shall be entitled to recover all its fees, costs
and expenses incurred in connection with such proceeding, including (but not
limited to) reasonable fees and expenses of attorneys and accountants and
including (but not limited to) all such fees, costs and expenses incurred in
connection with any appeals and/or in connection with the enforcement of any
judgment or award rendered in such proceeding.

     IN WITNESS WHEREOF, the Company has duly caused this Warrant to be
signed by its duly authorized officer and to be dated as of February 26, 2000.

                                             EXELIXIS, INC.

                                             By: /s/ Glen Y. Sato
                                                -------------------------------
                                                Name: Glen Y. Sato
                                                Title: Chief Financial Officer

                                       10

<PAGE>

                                EXHIBIT A

                             SUBSCRIPTION FORM

                                                  Dated ___________, ______

Exelixis, Inc.
260 Littlefield Avenue
South San Francisco, CA 94080
Attention: Chief Financial Officer

Ladies and Gentlemen:

__________ The undersigned hereby elects to exercise the warrant issued to it by
           Exelixis, Inc. (the "Company") and dated March ___, 2000, Warrant
           No.___ (the "Warrant") and to purchase thereunder
           __________________________________ shares of the Common Stock of the
           Company (the "Shares") at a purchase price of
           ___________________________________________ Dollars ($__________) per
           Share or an aggregate purchase price of
           __________________________________ Dollars ($__________) (the
           "Purchase Price"); or

__________ The undersigned hereby elects to convert _______ percent (___%) of
           the value of the Warrant pursuant to the provisions of Section 2.2 of
           the Warrant.

     Pursuant to the terms of the Warrant the undersigned has delivered the
Purchase Price herewith in full in cash or by certified check or wire transfer
(unless the second alternative above has been marked).

                                                   Very truly yours,

                                                   _____________________________

                                                   By:__________________________

                                                   Title:_______________________

                                       11

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