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                COMMON STOCK SALE/REPURCHASE AGREEMENT

    AGREEMENT made as of August 6, 1997 by and between ISRAEL CHEMICALS, 
LTD., an Israeli limited liability company ("ICL"), and SUPERGEN, INC., a 
California company ("Company").

    WHEREAS, ICL owns 2,571,000 Shares of the common stock of the Company 
(the "ICL Shares); and

    WHEREAS, ICL wishes to sell and the Company wishes to repurchase 740,000 
of the ICL Shares on the terms and conditions set forth below.

    NOW, THEREFORE, in consideration of the mutual covenants, agreements, 
representations and warranties herein contained and of other good and 
valuable consideration, the receipt and sufficiency of which is hereby 
acknowledged, the parties hereby agree as follows:

    1.   SALE AND REPURCHASE OF STOCK.  Subject to the conditions set forth 
in Section 10, at the Closing (as defined below), ICL shall sell to the 
Company and the Company shall repurchase from ICL 740,000 of its shares of 
the common stock of the Company (the "Repurchased Shares") at a price per 
share equal to $10.63, for an aggregate amount of $7,866,200 (the "Purchase 
Price").

    2.   CLOSING.  The closing of the sale and repurchase of the Repurchased 
Shares shall take place no later than 1:00 p.m. New York City time on August 
6, 1997 (the "Closing Date") at the offices of Robinson Silverman Pearce 
Aronsohn & Berman LLP, 1290 Avenue of the Americas, New York, New York 10104, 
or such other place and time as shall be mutually agreed upon by the parties.

    3.   DELIVERIES BY THE COMPANY AND ICL AT THE CLOSING.  At the Closing, 
the Company shall deliver to ICL (i) the Purchase Price, without deduction 
for any taxes, withholdings or other amounts, in United States dollars in 
immediately available funds by wire transfer to the account designated by ICL 
on the signature page hereof, and (ii) evidence that the Transfer Agent (as 
defined below) has received the Required Documents (as defined in Section 
10(a) below) and has been instructed to release to the Escrow Agent (as 
defined below) the New Certificates (as defined in Section 10(a) below).  ICL 
shall deliver to the Company the stock certificate(s) representing the 
Repurchased Shares, duly endorsed for transfer, and shall deliver to an 
escrow agent mutually agreed upon by all the parties (the "Escrow Agent") the 
stock certificates representing the Remaining ICL Shares (as defined in 
Section 7 below), to be held on terms and conditions set forth in an escrow 
agreement substantially in the form attached hereto as EXHIBIT A ("Escrow 
Agreement").


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    4.   REPLACEMENT CERTIFICATES.  On or prior to Closing, ICL shall deliver 
to the Transfer Agent the three (3) stock certificates representing, in the 
aggregate, the total amount of the ICL Shares and the Company shall cause the 
Transfer Agent to deliver, in lieu of and in full substitution for such 
certificates, three (3) stock certificates issued by the Company to ICL, one 
representing the total amount of the Repurchased Shares, the second 
representing the total amount of the Option Shares ("Option Share 
Certificate") and the third representing the total amount of the Remaining 
ICL Shares less the Option Shares ("Remaining Share Certificate").  The 
Option Share Certificate and the Remaining Share Certificate shall be 
delivered by the Transfer Agent to the Escrow Agent without any legends or 
restrictions on such certificates, subject to the restrictions set forth in 
this Agreement and the Escrow Agreement.

    5.   REPRESENTATIONS AND WARRANTIES OF THE COMPANY.  The Company hereby 
makes the following representations and warranties to ICL as of the Closing 
Date:

    a.   ORGANIZATION.  The Company is a corporation, duly incorporated,
    validly existing and in good standing under the laws of the jurisdiction 
    of its incorporation.

    b.   AUTHORIZATION; ENFORCEABILITY.  The Company has the requisite
    corporate power and authority to enter into and consummate the transactions
    contemplated hereby.  The execution and delivery of this Agreement by the
    Company and the consummation by it of the transactions contemplated hereby
    have been duly authorized by all necessary action on the part of the
    Company.  This Agreement has been duly executed and delivered by the
    Company and constitutes the legal, valid and binding obligation of the
    Company enforceable against it in accordance with its terms, except as such
    enforceability may be limited by applicable bankruptcy, insolvency,
    reorganization, liquidation or similar laws relating to or affecting
    generally the enforcement of creditors' rights and remedies or by other
    equitable principles of general application.

    c.   NO CONFLICTS.  The execution, delivery and performance of this
    Agreement by the Company and the consummation by it of the transactions
    contemplated hereby do not and will not (i) violate any provision of its
    certificate of incorporation or bylaws, or (ii) conflict with, or
    constitute a default (or an event which, with notice or lapse of time or
    both, would become a default) under, or give to others any rights of
    termination, amendment, acceleration or cancellation of, any material
    agreement, indenture or instrument to which the Company is party or result
    in a violation of any order, judgement, injunction, decree to other
    restriction of any court of competent jurisdiction or governmental
    authority to which the Company is subject or by which any property or asset
    of the Company is bound or affected.

    d.   LITIGATION; PROCEEDINGS.  There is no action, suit, notice of
    violation, proceeding or investigation pending, or to the knowledge of the
    Company, threatened against or affecting 


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    the Company or any of its affiliates or any of their respective 
    properties before or by any court, governmental or administrative 
    agency or regulatory authority (federal, state, county, local or 
    foreign) that relates to or challenges the legality, validity or 
    enforceability of this Agreement.

    e.   BROKERS' FEES. There are no brokerage fees, commissions or
    compensation due to any party engaged or retained by, through or on behalf
    of, the Company in connection with the transactions contemplated hereby.

    f.   USE OF FUNDS.  The Company is permitted, under applicable laws and
    under (i) its articles of incorporation, by-laws and (ii) any material
    agreement, indenture or instrument to which the Company or any of its
    affiliates is bound, to use the funds being allocated by the Company as the
    Purchase Price hereunder for a repurchase or redemption of its common stock
    as contemplated by this Agreement.

    6.   REPRESENTATIONS AND WARRANTIES OF ICL.   ICL hereby makes the
following representations and warranties to the Company as of the Closing Date:

    a.   AUTHORIZATION: ENFORCEABILITY.  ICL has the requisite corporate power
    and authority to enter into and consummate the transactions contemplated
    hereby.  The execution and delivery of this Agreement by ICL and the
    consummation by it of the transactions contemplated hereby have been duly
    authorized by all necessary action on the part of ICL.  This Agreement has
    been duly executed and delivered by ICL and constitutes the legal, valid
    and binding obligation of ICL enforceable against it in accordance with its
    terms, except as such enforceability may be limited by applicable
    bankruptcy, insolvency, reorganization, liquidation or similar laws
    relating to or affecting generally the enforcement of creditors' rights and
    remedies or by other equitable principles of general application.

    b.   NO CONFLICTS.  The execution, delivery and performance of this
    Agreement by ICL and the consummation by it of the transactions
    contemplated hereby do not and will not (i) violate any provision of its
    Memorandum or Articles of Association, or (ii) conflict with, or constitute
    a default (or an event which, with notice or lapse of time or both, would
    become a default) under, or give to others any rights of termination,
    amendment, acceleration or cancellation of, any material agreement,
    indenture or instrument to which ICL is party or result in a violation of
    any order, judgement, injunction, decree to other restriction of any court
    of competent jurisdiction or governmental authority to which ICL is subject
    or by which any property or asset of ICL is bound or affected.

    c.   LITIGATION: PROCEEDINGS.  There is no action, suit, notice of
    violation, proceeding or investigation pending, or to the knowledge of ICL,
    threatened against or affecting ICL or any 


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    of its affiliates or any of their respective properties before or by 
    any court, governmental or administrative agency or regulatory 
    authority (federal, state, county, local or foreign) that relates to or 
    challenges the legality, validity or enforceability of this Agreement.

    d.   GOVERNMENT CONSENTS.  To the best of its knowledge, no consent or
    other approval of any governmental authority, including but not limited to
    the Israeli government, is required in connection with the execution,
    delivery and performance by ICL of this Agreement.

    e.   OWNERSHIP; TITLE.  ICL has, and upon Closing will deliver to the
    Company, good and marketable title to the Repurchased Shares.  ICL is the
    record and beneficial owner of the Repurchased Shares and Option Shares,
    free and clear of any liens, claims, charges or other encumbrances
    whatsoever.  Other than the ICL Shares, ICL does not own, of record or
    beneficially, directly or indirectly, shares of, or any subscription,
    warrant, option (other than the Put Option hereunder) or, to its knowledge,
    other rights (such as preemptive rights or rights of first refusal) to
    purchase or acquire shares of, any class of capital stock of the Company or
    securities convertible into or exchangeable for such capital stock and has
    no intent to acquire any such shares or any such rights.

    f.   BROKERS' FEES.  Other than a fee payable to Lehman Brothers, Inc.,
    there are no brokerage fees, commissions or compensation due to any party
    engaged or retained by, through or on behalf of, ICL in connection with the
    transactions contemplated hereby.

    g.   NON-AFFILIATE OF THE COMPANY.  ICL (i) is not a member of a "group" as
defined in Rule 13d-5(b)(1) of the Securities Exchange Act of 1934, as amended,
and (ii) does not have and will not seek, directly or indirectly, the power to
direct or cause the direction of the management or policies of the Company or
otherwise control the Company.  None of ICL's current officers, directors,
employees or affiliates is or has a right to become or shall, with ICL's
consent, seek to become in the future officers or directors of the Company.

    7.   OTHER AGREEMENTS BY ICL.  Upon the Closing, ICL agrees that (i) the 
Amended and Restated Stock Purchase Agreement among ICL, the Company and 
certain founders of the Company, dated May 30, 1995, shall be terminated and 
shall be null and void and of no further force and effect, inclusive of the 
rights and obligations set forth in Section 6.2 and 8.1(a) thereof; (ii) the 
Letter Agreement dated March 6, 1996 between the Company and ICL shall be 
terminated and shall be void and of no further force and effect, and (iii) 
that, except as set forth in Section 9, ICL will not, without the prior 
consent of the Company, sell, make short sale of, loan, grant any options for 
the purchase of or otherwise dispose of any of the ICL Shares remaining after 
the sale to the Company of the Repurchased Stock (the "Remaining ICL Shares") 
for a period of 180 days from the Closing Date (the "Lock-Up Period").  After 
the date hereof, ICL shall not acquire any shares or any subscription, 


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warrant, option or other rights (including, without limitation, preemptive 
rights or rights of first refusal) to purchase or acquire shares of any class 
of the capital stock of the Company.

    8.   COVENANTS OF THE COMPANY.  The Company covenants and agrees that, 
from and after the Closing Date: (i) it will not intentionally take any 
action or other steps which shall cause ICL to become or be deemed to be an 
"affiliate" as defined in Rule 144(a) of the Securities Act of 1933, as 
amended ("Act") or Rule 405 of the Act (an "Affiliate"), and (ii) as long as 
ICL does not take any action or other steps which cause (x) its 
representations and warranties hereunder to become false, inaccurate or 
invalid; (y) it to become or to be deemed to be an Affiliate; or (z) it to be 
in breach of Section 7 or in material breach of Section 9, the Company will 
not issue any stop transfer instructions with respect to the New Certificates 
or any of the Remaining ICL Shares, or otherwise seek to place restrictions 
on the transfer of any of the Remaining ICL Shares.

    9.   PUT/CALL OPTIONS. (a)  PUT OPTION.  In consideration of ICL's 
agreements as set forth in Section 7, ICL shall have the right to sell to the 
Company and require the Company to purchase any number or all of 915,500 of 
the Remaining ICL Shares (the "Option Shares"), at a price per share of 
$13.50, at any time during the Option Period, as defined below (the "Put 
Option").  ICL may exercise such right at any time or from time to time 
during the Option Period upon written notice of not less than ten (10) 
business days to the Company ("Put Notice").  The Put Notice shall set forth 
the number of Option Shares being tendered and the aggregate price to be paid 
therefor.

         (b)  CALL OPTION.  At any time or from time to time during the 
Option Period, the Company shall have the right to require ICL to sell to the 
Company, and to purchase, any number or all of the Option Shares, at a price 
per share of $13.50 (the "Call Option").  The Company may exercise such right 
at any time or from time to time during the Option Period upon written notice 
of not less than ten (10) business days to ICL ("Call Notice").  The Call 
Notice shall set forth the number of Option Shares to be purchased and the 
aggregate price to be paid therefor.

         (c)  OPTION PERIOD.  The Put Option and the Call Option are 
respectively exercisable during the period commencing on the date which is 40 
days after the 20th consecutive trading day on which the closing bid price of 
the Company's common stock (as reported by the NASDAQ or such other exchange 
on which the Company's shares of common stock shall then be listed for 
trading) exceeds $18.00 per share (the "Effective Date") and terminating on 
the later to occur of (i) 90 days following the Effective Date and (ii) the 
last day of the Lock-Up Period (the "Option Period").

         (d)  CLOSINGS.  Closing of a purchase and sale pursuant to a Put 
Option or Call Option hereunder shall take place not more than 30 business 
days from the date the Put Notice or Call Notice (as the case may be) was 
delivered to the relevant party at a time and place mutually agreeable to the 
parties. Notwithstanding the 10-day notice period which each party has 
pursuant to 


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paragraphs (a) and (b) above to deliver the Put Notice or Call Notice (as the 
case may be), such Notice shall be delivered on the earlier to occur of (x) 
the expiration of such 10 business day period and (y) the last day of the 
Option Period.  At the closing, (A) ICL shall (i) deliver or cause the Escrow 
Agent (as described below in this paragraph (d)) to deliver the 
certificate(s) representing the Option Shares being purchased and sold to the 
Company, duly endorsed for transfer, and (ii) deliver a certificate executed 
by an officer of ICL, dated the date of such closing, containing the 
representations and warranties set forth in Section 6(c) and (e), as such 
representations and warranties relate to the Option Shares to be purchased 
and sold; and (B) the Company shall deliver (i) the purchase price to ICL or 
to its order for the Option Shares in immediately available funds by wire 
transfer, and (ii) a certificate executed by an officer of the Company, dated 
the date of such closing, containing the representations and warranties set 
forth in Section 5(d) and (f), as such representations and warranties relate 
to the Option Shares to be purchased and sold.  Either the Company or ICL 
shall deliver a letter executed by both parties to the Escrow Agent 
instructing such Escrow Agent to release the Option Shares subject to a 
closing hereunder in accordance with the procedure set forth therefor in the 
Escrow Agreement.  A closing of the exercise of a Put Option or Call Option 
in accordance with the terms hereof may occur subsequent to the expiration of 
the Option Period, provided that the Put Option or Call Option (as the case 
may be) was exercised, and the Put Notice or Call Notice (as the case may be) 
was delivered, prior to the expiration of the Option Period.

         (e)  CANCELLATION OF PUT/CALL.  Upon the exercise of a Put Option by 
ICL, the Call Option held by the Company as to the same number of Option 
Shares shall be automatically cancelled, and conversely, upon the exercise of 
a Call Option by the Company, the Put Option held by ICL as to the same 
number of Option Shares shall be automatically cancelled.

         (f)  EXPIRATION OF OPTIONS.  Notwithstanding the foregoing, in the 
event that the Effective Date does not occur during the Lock-Up Period, all 
Put Options and Call Options granted hereunder shall expire and terminate as 
of the last day of such Lock-Up Period.

    10.  CONDITIONS PRECEDENT TO CLOSING.  The Closing shall be subject to the
following: 

    (a)  DELIVERY OF REQUIRED DOCUMENTS.  The Company shall have delivered to
    ICL or its counsel, prior to the Closing Date, a copy of the executed and
    issued legal opinion of the Company's counsel, together with written
    instructions or such other documents or instruments, all in form and
    substance satisfactory to, and as shall be required by, the Company's
    transfer agent and registrar, ChaseMellon Shareholder Services, L.L.C. (the
    "Transfer Agent") (the "Required Documents"), enabling the Transfer Agent
    to issue in the name of ICL and deliver to the Escrow Agent, upon delivery
    by ICL to such Transfer Agent of the stock certificates representing the
    Remaining ICL Shares, the Option Share Certificate and the Remaining Share
    Certificate without any stamps or any other restrictive legends


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    (collectively, the "New Certificates"), thereby enabling ICL and otherwise
    confirming its right to sell any or all of the Remaining ICL Shares
    (subject to the terms of this Agreement) pursuant to Rule 144(k)
    promulgated under the Act ("Rule 144(k)").

    (b)  REPRESENTATIONS AND WARRANTIES.   The representations and warranties
    contained herein shall be true and correct as if made on and as of the
    Closing Date and each party shall have performed and observed its
    agreements as set forth herein.

    (c)  PURCHASE PRICE; INSTRUCTIONS. ICL shall have received (i) the Purchase
    Price in immediately available funds, and (ii) evidence that the Transfer
    Agent has received instructions to release to ICL the New Certificates, in
    accordance with Section 3.

    (d)  STOCK CERTIFICATES.  The Company shall have received from ICL the
    stock certificate representing the Repurchased Shares, duly endorsed for
    transfer.

    (e)  LEGAL OPINION OF ICL COUNSEL.  The Company shall have received a copy
    of the legal opinion of Robinson Silverman Pearce Aronsohn & Berman LLP,
    counsel to ICL the Company, issued to ICL, covering substantially the legal
    matters set forth in the opinion of the Company's counsel issued to the
    Company pursuant to paragraph (a) hereof.

    (f)  ESCROW AGREEMENT.  The parties and the Escrow Agent shall have entered
    into the Escrow Agreement and the Transfer Agent shall have delivered the
    New Certificates representing the Remaining ICL Shares to the Escrow Agent.

    11.  EXPENSES.  Each party shall pay the fees and expenses of its advisers,
brokers, counsel or other experts, if any, and all other expenses incurred by
such party incident to the negotiation, preparation, delivery and performance 
of this Agreement.

    12.  NOTICES.  All notices and other communications under this Agreement 
must be in writing and shall be telecopied, hand delivered or transmitted by 
courier as follows:

         IF ICL TO:
              
              Israel Chemicals, Ltd.
              Beit Noam, 21 Shazar Av.
              P.O. B. 725
              Beer Sheva, 84106, Israel

              Attention: Motti Levin, SVP
              Telecopier. 972-7-628-6563


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         IF TO THE COMPANY TO:
              
              SuperGen, Inc.
              Two Annabel Lane, Suite 220
              San Ramon, CA 94593

              Attention: Dr. Joseph Rubinfeld
              Telecopier: 510-904-1918

All such notices and communications shall be effective when sent if by 
telecopier, and if hand-delivered or transmitted by courier, when received. 
Either party may change the address and/or telecopier number to which notices 
are sent by giving the other written notice thereof.

    13.  BINDING AGREEMENT.  This Agreement shall be binding upon and inure 
to the benefit of each party and its respective successors and assigns.  This 
Agreement may not be assigned by either party and any attempted assignment 
shall be void.

    14.  CONFIDENTIALITY.  Except as provided below, each party shall keep 
confidential and not publicly disclose the terms of this Agreement and the 
transactions contemplated hereby.  Each party further agrees that it shall 
not disclose to any third party nor utilize any material confidential 
information or trade secret received from or disclosed by the other party 
prior to the date of this Agreement, whether or not such confidential 
information or trade secret was received or disclosed pursuant to an 
agreement or arrangement between the parties.  the term "confidential 
information" or "trade secret" shall not include any information which has, 
is or shall become generally available to the public other than by breach of 
this provision.  Nothing in this Section 14 shall prevent either party from 
making disclosures reasonably necessary to effectuate the transactions 
contemplared hereby or as required by law including, without limitation, any 
reporting obligations or other requirements imposed on either party under 
applicable laws, rules and regulations.

    15.  FURTHER ASSURANCES.  Each party shall cooperate, take such further 
action and execute such further documents, including, without limitation, any 
documents or certificates as may be reasonably requested by the other party 
in order to carry out the terms of this Agreement and the transactions 
contemplated hereby.

    16.  ENTIRE AGREEMENT.   This Agreement constitutes the entire 
understanding of the parties with respect to the subject matter hereof and 
may not be modified, amended or terminated, nor may any provision hereof be 
waived, except by a writing signed by both parties. This Agreement supersedes 
any and all agreements or arrangements between ICL and the Company, written 
or oral including, without limitation, that certain Letter Agreement dated 
July 18, 1997 between Lehman Brothers, acting as agent for ICL, and the 
Company.


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    17.  COUNTERPART SIGNATURES.  This Agreement may be executed in several 
counterparts, all of which shall constitute but one agreement, binding on 
both parties, it being understood that both parties need not sign the same 
counterpart.

    18.  GOVERNING LAW.  This Agreement shall be governed by and construed in 
accordance with the laws of the State of Delaware without regard to conflict 
of law principles.

    IN WITNESS WHEREOF,  the parties hereto have caused this Agreement to be 
duly executed by their respective authorized officers as of the date first 
written above.

ISRAEL CHEMICALS, LTD.                      SUPERGEN, INC.

By: /s/ MOTTI LEVIN                        By:/s/ DR. JOSEPH RUBINFELD
   ----------------------------                --------------------------------
Name:                                       Name:
Title:  Senior Vice President               Title:  Chairman, Chief Executive
                                                    Officer and President

WIRE TRANSFER INSTRUCTIONS:

Bank Hapoalim, Main Branch
Tel Aviv, Israel
Acct. #600-655062


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