Document:

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                                 SUPERGEN, INC.
                           TWO ANNABEL LANE, SUITE 220
                               SAN RAMON, CA 94583

                               AVI BIOPHARMA, INC.
                           ONE SW COLUMBIA, SUITE 1105
                               PORTLAND, OR 97258

                   COMMON STOCK AND WARRANT PURCHASE AGREEMENT

                                  APRIL 4, 2000

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                                TABLE OF CONTENTS

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TABLE OF CONTENTS.....................................................................................................i

SECTION 1 Authorization and Sale of SECURITIES........................................................................1
         1.1      AUTHORIZATION.......................................................................................1
         1.2      SALE OF SHARES BY AVI...............................................................................2
         1.3      SUBSEQUENT ISSUANCE OF SHARES BY SUPERGEN...........................................................2
         1.4      WARRANT.............................................................................................2

SECTION 2 Closing Date; Delivery
         2.1      CLOSING.............................................................................................3
         2.2      SUBSEQUENT CLOSINGS.................................................................................3
         2.3      WARRANT EXERCISE CLOSING............................................................................3
         2.4      DELIVERY............................................................................................3

SECTION 3 Representations and Warranties of AVI.......................................................................4
         3.1      ORGANIZATION; STANDING AND POWER; QUALIFICATION.....................................................4
         3.2      CAPITALIZATION......................................................................................4
         3.3      AUTHORIZATION; NO CONFLICTS; APPROVALS..............................................................5
         3.4      FINANCIAL STATEMENTS................................................................................6
         3.5      ABSENCE OF UNDISCLOSED LIABILITIES..................................................................6
         3.6      ABSENCE OF CERTAIN CHANGES OR EVENTS................................................................6
         3.7      TAXES...............................................................................................7
         3.8      INTELLECTUAL PROPERTY...............................................................................8
         3.9      ENVIRONMENTAL MATTERS...............................................................................8
         3.10     SEC FILINGS.........................................................................................8
         3.11     LISTING.............................................................................................8
         3.12     EMPLOYEE BENEFIT PLANS..............................................................................8
         3.13     EMPLOYEES...........................................................................................9
         3.14     BROKERS OR FINDERS..................................................................................9
         3.15     COMPLIANCE WITH LAWS................................................................................9
         3.16     LITIGATION..........................................................................................9
         3.17     NO MISREPRESENTATION...............................................................................10
         3.18     INVESTMENT AVI.....................................................................................10
         3.19     VALID PRIVATE PLACEMENT............................................................................10
         3.20     OREGON BUSINESS CORPORATION ACT....................................................................10
         3.21     EXEMPT OFFERING; ACQUISITION FOR INVESTMENT........................................................11
         3.22     ACCESS TO INFORMATION; INVESTMENT EXPERIENCE; NO RELIANCE..........................................12

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SECTION 4 Representations and Warranties of SuperGen.................................................................13
         4.1      ORGANIZATION; STANDING AND POWER; QUALIFICATION....................................................13
         4.2      CAPITALIZATION.....................................................................................13
         4.3      AUTHORIZATION; NO CONFLICTS; APPROVALS.............................................................13
         4.4      FINANCIAL STATEMENTS...............................................................................15
         4.5      ABSENCE OF UNDISCLOSED LIABILITIES.................................................................15
         4.6      ABSENCE OF CERTAIN CHANGES OR EVENTS...............................................................15
         4.7      TAXES..............................................................................................16
         4.8      INTELLECTUAL PROPERTY..............................................................................16
         4.9      ENVIRONMENTAL MATTERS..............................................................................17
         4.10     SEC FILINGS........................................................................................17
         4.11     LISTING............................................................................................17
         4.12     EMPLOYEE BENEFIT PLANS.............................................................................17
         4.13     EMPLOYEES..........................................................................................17
         4.14     BROKERS OR FINDERS.................................................................................18
         4.15     COMPLIANCE WITH LAWS...............................................................................18
         4.16     LITIGATION.........................................................................................18
         4.17     NO MISREPRESENTATION...............................................................................18
         4.18     VALID PRIVATE PLACEMENT............................................................................19
         4.19     SECTION 203........................................................................................19
         4.20     EXEMPT OFFERING; ACQUISITION FOR INVESTMENT........................................................19
         4.21     ACCESS TO INFORMATION; INVESTMENT EXPERIENCE; NO RELIANCE..........................................20
         4.22     BROKERS OR FINDERS.................................................................................21

SECTION 5 Additional Agreements......................................................................................21
         5.1      FINANCIAL STATEMENTS AND OTHER REPORTS.............................................................21
         5.2      CONFIDENTIALITY....................................................................................22
         5.3      PUBLIC ANNOUNCEMENTS...............................................................................22
         5.4      HSR ACT............................................................................................22
         5.5      RESTRICTIONS ON TRANSFER...........................................................................23
         5.6      LEGENDS............................................................................................23
         5.7      FURTHER ASSURANCES.................................................................................25
         5.8      USE OF FUNDS.......................................................................................25
         5.9      REGISTRATION RIGHTS AGREEMENT......................................................................26

SECTION 6 Conditions to Closings.....................................................................................26
         6.1      CONDITIONS TO SUPERGEN'S OBLIGATION TO ACQUIRE THE AVI SHARES......................................26
         6.2      CONDITIONS TO AVI'S OBLIGATION TO ISSUE THE SHARES.................................................27
         6.3      CONDITIONS TO THE INITIAL WARRANT CLOSING..........................................................27

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SECTION 7 Miscellaneous..............................................................................................28
         7.1      ACCESS TO INFORMATION..............................................................................28
         7.2      WAIVERS AND AMENDMENTS.............................................................................28
         7.3      GOVERNING LAW......................................................................................28
         7.4      SURVIVAL...........................................................................................28
         7.5      SUCCESSORS AND ASSIGNS.............................................................................28
         7.6      ENTIRE AGREEMENT...................................................................................28
         7.7      NOTICES............................................................................................28
         7.8      SEVERABILITY.......................................................................................29
         7.9      EXPENSES...........................................................................................29
         7.10     TITLES AND SUBTITLES...............................................................................29
         7.11     CALIFORNIA CORPORATE SECURITIES LAW................................................................29
         7.12     COUNTERPARTS.......................................................................................29
         7.13     DELAYS OR OMISSIONS................................................................................29
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                                     -iii-
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         EXHIBITS

                  A        Form Warrant
                  B        Form Registration Rights Agreement

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                               AVI BIOPHARMA, INC.
                                 SUPERGEN, INC.

                   COMMON STOCK AND WARRANT PURCHASE AGREEMENT

         THIS COMMON STOCK AND WARRANT PURCHASE AGREEMENT (the "AGREEMENT") is
made as of April 4, 2000 by and between AVI BioPharma, Inc., an Oregon
corporation ("AVI"), and SuperGen, Inc., a Delaware corporation ("SUPERGEN").

                                    RECITALS

         WHEREAS, AVI is developing a pharmaceutical compound known as Avicine
for the treatment of colorectal cancer and other indications;

         WHEREAS, AVI desires to collaborate with SuperGen with respect to the
clinical development, obtaining of regulatory approvals, distribution and
marketing of Avicine product(s) in the United States;

         WHEREAS, SuperGen desires to collaborate with AVI with respect to such
product(s); and

         WHEREAS, in support of their collaboration, SuperGen and AVI shall
enter into that certain United States of America Sales, Distribution, and
Development Agreement (the "U.S. AGREEMENT"), which provides, among other
things, that SuperGen will make equity investments in AVI in consideration of
cash or its own common stock;

         NOW, THEREFORE, in consideration of the foregoing and the mutual
covenant undertakings contained herein, the parties hereto hereby agree as
follows:

                                    SECTION 1

                      AUTHORIZATION AND SALE OF SECURITIES

         1.1 AUTHORIZATION. AVI will, prior to the Closing Date or the Warrant
Closing Date (as defined below), authorize the sale and issuance of the number
of shares (the "AVI Shares") and Warrant Shares (as defined below) of its Common
Stock (the "AVI Common Stock") pursuant to the terms of this Agreement. SuperGen
will, prior to the Closing Date and the applicable Subsequent Closing Date (as
defined below), authorize the sale and issuance of the number of shares (the
"SuperGen Shares") of its Common Stock (the "SuperGen Common Stock") pursuant to
the terms of this Agreement.

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         1.2 SALE OF SHARES BY AVI. Subject to the terms and conditions of this
Agreement and the terms and conditions of the U.S. Agreement, SuperGen agrees to
purchase and AVI agrees to sell and issue to SuperGen 1,684,211 shares of AVI's
common stock ("AVI COMMON STOCK") for consideration consisting of $5,000,000 in
cash and 347,826 in SuperGen's common stock ("SUPERGEN COMMON STOCK").

         1.3 SUBSEQUENT ISSUANCE OF SHARES BY SUPERGEN. Subject to the terms and
conditions of this Agreement and the terms and conditions of the U.S. Agreement,
SuperGen may make milestone payments to AVI in SuperGen Common Stock pursuant to
Sections 5(b), (c) and (d) of the U.S. Agreement in an aggregate amount of up to
$10,000,000, to be completed in up to three (3) subsequent closings (each a
"SUBSEQUENT CLOSING," the closing date for each Subsequent Closing referred to
as a "SUBSEQUENT CLOSING DATE"). The valuation of SuperGen Common Stock for
purposes of such milestone payments shall be the average of the closing prices
of SuperGen Common Stock over the twenty (20) trading days commencing ten (10)
trading days immediately preceding the Relevant Date (as defined below). For
purposes of this Agreement, Relevant Date means, (i) in the case of a Subsequent
Closing pursuant to Section 5.1(b) of the U.S. Agreement, the business day upon
which the condition set forth in Section 5.1(b) of the U.S. Agreement is
satisfied, (ii) in the case of a Subsequent Closing pursuant to Section 5.1(c)
of the U.S. Agreement, the business day upon which the condition set forth in
Section 5.1(c) of the U.S. Agreement is satisfied; and (iii) in the case of a
Subsequent Closing pursuant to Section 5.1(d) of the U.S. Agreement, the
business day upon which the condition set forth in Section 5.1(d) of the U.S.
Agreement is satisfied. The number of SuperGen Shares to be issued to AVI in
each Subsequent Closing shall be that number of SuperGen Shares which, at the
valuation specified above, are valued as near as possible to the dollar value
set forth in the corresponding section of the U.S. Agreement. No fractions of
any shares shall be allotted pursuant to this Agreement and the shares issued
hereunder shall be rounded up to the nearest whole number of shares.

         1.4 WARRANT. Subject to the terms and conditions of this agreement and
the U.S. Agreement, AVI shall issue a Warrant to SuperGen upon SuperGen's
request, in substantially the form attached hereto as EXHIBIT A to this
Agreement, to purchase up to 1,665,478 shares of AVI Common Stock, subject to
anti-dilution provisions. The exercise price for the Warrant shall be $35.625,
300% of the purchase price per AVI Share specified under Section 1.2 of this
Agreement (the "WARRANT PRICE") (such price to be adjusted pursuant to the terms
of the Warrant), and the Warrant shall be exercisable at any time, or from time
to time, in whole or in part, for a three year period commencing on the earlier
of (i) the date the U.S. Food and Drug Administration (the "FDA") accepts the
new drug application submitted for the product (as defined in the U.S.
Agreement) or (ii) the date on which the closing price of AVI Common Stock
exceeds the Warrant Price (shares to be purchased upon exercise of the Warrant
are hereinafter referred to as the "WARRANT SHARES").

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         For purposes of this Agreement, the number of Warrant Shares of AVI
Common Stock, including the anti-dilution provisions, shall be calculated at the
time SuperGen first exercises the Warrant based on the following formula:

                           OP = (0.10 X (OS + (10/90 X OS)))

              -    OP means the number of Warrant Shares.
              -    OS means the total number of shares of AVI Common Stock then
                   outstanding.

                                    SECTION 2

                             CLOSING DATE; DELIVERY

         2.1 CLOSING. Purchase and sale of the AVI Shares and the issuance of
the SuperGen Shares as set forth in Section 1.2 hereunder shall take place in
accordance with Section 5.1(a) of the U.S. Agreement at a closing ("CLOSING") to
occur upon the satisfaction of all of the conditions set forth in Sections 6.1
and 6.2 hereof and Section 16.11 of the U.S. Agreement (the "CLOSING DATE"). The
Closing shall be held at the offices of Wilson Sonsini Goodrich & Rosati, 650
Page Mill Road, Palo Alto, California, at 10:00 a.m. local time, on the Closing
Date, or at such other time and place upon which AVI and SuperGen shall agree.

         2.2 SUBSEQUENT CLOSINGS. The Subsequent Closings for issuance of
SuperGen Shares to AVI under Section 1.3 hereunder shall take place at closings
to occur on the applicable Subsequent Closing Date, which shall be the fifth
business day following any Relevant Date. The Subsequent Closings shall be held
at the offices of Wilson Sonsini Goodrich & Rosati, 650 Page Mill Road, Palo
Alto, California, at 10:00 a.m. local time, on any Subsequent Closing Date, or
at such other time and place upon which AVI and SuperGen shall agree.

         2.3 WARRANT EXERCISE CLOSING. The closing for SuperGen's initial
exercise of the Warrant ("INITIAL WARRANT CLOSING") shall be held at the offices
of Wilson Sonsini Goodrich & Rosati, 650 Page Mill Road, Palo Alto, California,
at 10:00 a.m. local time, three business days following the receipt by AVI of
SuperGen's Notice of Exercise ("WARRANT CLOSING DATE"), or at such other time
and place upon which AVI and SuperGen shall agree.

         2.4  DELIVERY.

                  2.4.1 CLOSING. At the Closing, AVI shall cause the delivery to
SuperGen of certificates registered in SuperGen's name or as designated by
SuperGen evidencing the AVI Shares, upon the receipt of the portion of cash
payment for the AVI Shares as set forth in Section 1.2 above, by check payable
to AVI or wire transfer per AVI's instructions; and SuperGen shall cause the
delivery to AVI of certificates registered in AVI's name or as designated by AVI
evidencing the number of the SuperGen Shares specified in Section 1.2 hereunder.

                                      -3-
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                  2.4.2 SUBSEQUENT CLOSINGS. At each Subsequent Closing, AVI
shall cause the delivery to SuperGen of certificates registered in SuperGen's
name or as designated by SuperGen evidencing such number of AVI Shares
calculated according to Section 1.3.

                  2.4.3 WARRANT CLOSINGS. At the Initial Warrant Closing and
thereafter upon the receipt of Notice of Exercise, AVI shall cause the delivery
to SuperGen of certificates registered in SuperGen's name or as designated by
SuperGen in the Notice of Exercise representing the number of Warrant Shares as
specified in the Notice of Exercise.

                                    SECTION 3

                      REPRESENTATIONS AND WARRANTIES OF AVI

         Except as disclosed in AVI's SEC Filings (as defined in Section 3.10)
or as set forth in the disclosure schedule previously delivered to SuperGen (the
"AVI DISCLOSURE SCHEDULE"), AVI represents and warrants to SuperGen as follows:

         3.1 ORGANIZATION; STANDING AND POWER; QUALIFICATION. AVI and each of
its subsidiaries is a corporation duly organized and existing under, and by
virtue of, the laws of the State of Oregon and is in good standing under such
laws. AVI and each of its subsidiaries have all requisite corporate power to
own, lease and operate its property and to carry on its businesses, and is duly
qualified to do business and is in good standing as a foreign corporation in any
jurisdiction except where the failure to be so qualified and in good standing
would not have a material adverse effect on the business, assets (including
intangible assets), properties, liabilities (contingent or otherwise), financial
condition, operations, or results of operation of AVI or its subsidiaries, taken
as a whole (a "MATERIAL ADVERSE EFFECT").

         3.2 CAPITALIZATION. The authorized capital stock of AVI consists of
50,000,000 shares of AVI Common Stock, $0.0001 par value, and 2,000,000 shares
of preferred stock, $0.0001 par value. As of March 31, 2000, there were
16,658,784 shares of Common Stock issued and outstanding, 2,364,302 shares of
AVI Common Stock issuable under AVI's stock option plans and 5,438,963 shares
issuable pursuant to warrants and there were no issued and outstanding shares of
preferred stock. All such issued and outstanding shares have been duly
authorized and validly issued, are fully paid and nonassessable. Except as set
forth in the AVI Disclosure Schedule, no shares of AVI Common Stock are entitled
to preemptive rights or registration rights and there are no outstanding
options, warrants, scrip, rights to subscribe to, call or commitments of any
character whatsoever relating to, or securities or rights convertible into, any
shares of capital stock of AVI. Furthermore, except as set forth in this
Agreement and the AVI Disclosure Schedule, there are no contracts or commitments
by which AVI is or may become bound to issue additional shares of the capital
stock of AVI or options, securities or rights convertible into shares of capital
stock of AVI. AVI is not a party to, and it has no knowledge of, any agreement
restricting the voting or transfer of any shares of the capital stock of AVI
other than transfer restrictions imposed to satisfy state and federal securities

                                      -4-
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laws. Except as set forth in the AVI Disclosure Schedule, the offer and sale of
all capital stock, convertible securities, rights, warrants, or options of AVI
issued prior to the Closing complied with all applicable federal and state
securities laws. Each of AVI's subsidiaries is wholly-owned by AVI.

         3.3      AUTHORIZATION; NO CONFLICTS; APPROVALS.

                  3.3.1 All corporate action on the part of AVI, its
shareholders and its directors necessary for the authorization, execution,
delivery and performance of the Agreement by AVI, the authorization, sale,
issuance and delivery of the AVI Shares, the authorization and issuance of the
Warrant, and the authorization, sale, issuance and delivery of the Warrant
Shares (including any required shareholder authorization of the Warrant Shares),
and the performance of all of AVI's obligations under the Agreement has been
taken or will be taken prior to the Closing Date, the issuance of the Warrant or
the Warrant Closing Date. The Agreement, the Registration Rights Agreement and
any other documents (including the Warrant) required to be executed and
delivered by AVI hereunder (collectively, the "TRANSACTION DOCUMENTS"), when
executed and delivered by AVI, shall constitute valid and binding obligations of
AVI, enforceable in accordance with their terms, subject to laws of general
application relating to bankruptcy, insolvency and the relief of debtors and
rules of law governing specific performance, injunctive relief or other
equitable remedies. The AVI Shares and Warrant Shares, when issued in compliance
with the provisions of this Agreement, will be validly issued, fully paid and
nonassessable, and free of any liens or encumbrances, other than any permissible
liens or encumbrances created by or imposed upon the AVI Shares and Warrant
Shares by SuperGen; provided, however, that the AVI Shares and Warrant Shares
are subject to restrictions on transfer under state and/or federal securities
laws and as set forth in this Agreement.

                  3.3.2 The execution and delivery by AVI of this Agreement and
the other Transaction Documents do not, and the consummation of the transactions
contemplated hereby and thereby will not, (i) conflict with, or result in any
violation of or breach of any provision of the Articles of Incorporation or
Bylaws of AVI, (ii) result in any violation or breach of, or constitute (with or
without notice or lapse of time, or both) a default under, or give rise to a
right of termination, cancellation or acceleration of any obligation or loss of
any benefit under any license, assignment, note, mortgage, indenture, lease,
contract or other agreement or obligation to which AVI is a party or by which
AVI or any of its properties or assets may be bound, (iii) conflict with or
violate any judgment, order, decree, statute, law, ordinance, rule or regulation
or any material permit, concession, franchise or license applicable to AVI or
any of its properties or assets, except in the case of (ii) for such violations,
breaches, defaults, rights of termination, cancellation or acceleration, or
losses of benefits which would not be reasonably likely to have a Material
Adverse Effect.

                  3.3.3 No consent, approval, order or authorization of, or
registration, declaration or filing with, any governmental entity is required by
or with respect to AVI in connection with the execution and delivery of this
Agreement and the other Transaction Documents or the consummation of the
transactions contemplated hereby or thereby, except that the filing of one or
more notification

                                      -5-
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and report forms under the Hart Scott Rodino Antitrust Improvement Act of 1976
(the "HSR ACT") may be required with respect to the acquisition by SuperGen of
the AVI Shares and Warrant Shares, and except (i) such other consents,
approvals, orders, authorizations, registrations, declarations and filings as
may be required under applicable federal and state securities laws and the laws
of any foreign country, and (ii) such other consents, authorizations, filings,
approvals and registrations which, if not obtained or made, would not be
reasonably likely to have a Material Adverse Effect.

         3.4 FINANCIAL STATEMENTS. AVI has delivered to SuperGen copies of AVI's
audited consolidated financial statements (balance sheet, statement of
operations, statement of shareholders' equity, and statement of cash flows) for
the year ended December 31, 1999 (the "AVI FINANCIAL STATEMENTS"). AVI Financial
Statements were prepared in accordance with generally accepted accounting
principles ("GAAP") applied on a consistent basis throughout the periods
involved (except as may be otherwise indicated in such financial statements or
the notes thereto). AVI Financial Statements present fairly in all material
respects the financial position of AVI and its subsidiaries as of the respective
dates and the consolidated results of its operations and cash flows for the
periods indicated.

         3.5 ABSENCE OF UNDISCLOSED LIABILITIES. Neither AVI nor any of its
subsidiaries has any liabilities, either accrued or contingent (whether or not
required to be reflected in financial statements in accordance with GAAP), and
whether due or to become due, other than (i) liabilities reflected or provided
for on the balance sheet as of December 31, 1999 (the "AVI BALANCE SHEET")
contained in AVI Financial Statements, (ii) liabilities specifically described
in this Agreement or the AVI Disclosure Schedule, and (iii) normal or recurring
liabilities incurred since December 31, 1999 in the ordinary course of business
consistent with past practices that would not reasonably be expected to result
in a Material Adverse Effect.

         3.6 ABSENCE OF CERTAIN CHANGES OR EVENTS. Except as set forth in the
AVI Disclosure Schedule, and except as reflected in AVI Financial Statements,
since December 31, 1999, AVI and its subsidiaries have conducted their
businesses in the ordinary course and in a manner consistent with past
practices, and have not:

                  3.6.1 suffered any event or occurrence that has had or would
reasonably be expected to have a Material Adverse Effect;

                  3.6.2 declared, set aside or paid any dividend or made any
other distribution on or in respect of the shares of its capital stock or
declared any direct or indirect redemption, retirement, purchase or other
acquisition of such shares, except for purchases of stock from terminated
non-officer employees in the ordinary course of business and in a manner
consistent with past practices;

                  3.6.3 issued any shares of their capital stock or any
warrants, rights, or options for, or entered into any commitment relating to
such capital stock, except for issuances made in the ordinary course of business
in arm's length transactions for value and in a manner consistent with

                                      -6-
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past practices (including issuances made upon exercises and conversions of
employee and director stock options);

                  3.6.4 made any material change in the accounting methods or
practices they follow, whether for general financial or tax purposes, or any
change in depreciation or amortization policies or rates;

                  3.6.5 bought, rented, sold, leased, abandoned or otherwise
disposed of any real property or machinery, equipment or other operating
property except in the ordinary course of business and in a manner consistent
with past practices and in an amount that is not material to AVI and its
subsidiaries taken as a whole;

                  3.6.6 sold, assigned, transferred, licensed, pledged, or
otherwise disposed of or encumbered any patent, trademark, trade name, brand
name, FDA license or approval application, copyright (or pending application for
any patent, trademark or copyright), invention, work of authorship, process,
know-how, formula or trade secret or interest thereunder or other material
intangible asset, except for non-exclusive licenses which were granted in the
ordinary course of business and in a manner consistent with past practices and
in an amount that is not material to AVI and its subsidiaries taken as a whole;

                  3.6.7 entered into any material commitment or transaction
(including without limitation any borrowing or capital expenditure) other than
the transactions contemplated by this Agreement and the other Transaction
Documents; or

                  3.6.8 paid, loaned or advanced any amount to, or sold,
transferred or leased any properties or assets or rights under license to, or
entered into any agreement or arrangement with any of its officers, directors or
shareholders or any affiliate of any of the foregoing, other than employee
compensation and benefits and reimbursement of employment related business
expenses incurred in the ordinary course of business.

         3.7 TAXES. AVI (including its subsidiaries) has timely made or filed
all federal and state income and all other tax returns, reports and declarations
required by any jurisdiction to which it is subject and has paid all taxes and
other governmental assessments and charges, shown or determined to be due on
such returns, reports and declarations, except those being contested in good
faith and has set aside on its books provision reasonably adequate for the
payment of all taxes for periods subsequent to the periods to which such
returns, reports or declarations apply. There are no material unpaid taxes
claimed to be due by the taxing authority of any jurisdiction, and the officers
of AVI know of no basis for any such claim. To the best knowledge of AVI, there
are no pending or proposed audits or claims from any tax authority for
deficiencies, penalties or interest against AVI or its subsidiaries and the
officers of AVI know of no basis for any such audit or claim

                                      -7-
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         3.8 INTELLECTUAL PROPERTY. To AVI's knowledge after reasonable inquiry,
(i) each of AVI and its subsidiaries has the right to use, free and clear of all
liens, charges, claims and restrictions, all intellectual property, patents,
trademarks, service marks, trade names, copyrights, licenses and rights which
are material to its business as presently conducted and (ii) neither AVI nor any
of its subsidiaries is infringing upon or otherwise acting adversely to the
right or claimed right of any other person under or with respect to the
foregoing.

         3.9 ENVIRONMENTAL MATTERS. To AVI's knowledge after reasonable inquiry,
neither AVI nor any of its subsidiaries is in violation of any statute, rule,
regulation, decision or order of any governmental agency or body or any court,
domestic or foreign, relating to the use, disposal or release of hazardous or
toxic substances or relating to the protection or restoration of the environment
or human exposure to hazardous or toxic substances (collectively, "ENVIRONMENTAL
LAWS") which, individually or in aggregate, would have a Material Adverse
Effect. Except as set forth in the AVI Disclosure Schedule, to AVI's knowledge
after reasonable inquiry, neither AVI nor any of its subsidiaries owns or
operates any real property contaminated with any substance that is subject to
any Environmental Laws, is liable for any off-site disposal or contamination
pursuant to any Environmental Laws, or is subject to any claim relating to any
Environmental Laws, which violation, contamination, liability or claim would
individually or in aggregate have a Material Adverse Effect; and AVI is not
aware of any pending investigation that might lead to such a claim.

         3.10 SEC FILINGS. AVI has timely filed all reports, registration
statements, proxy statements and other materials, together with any amendments
thereto (the "SEC FILING"), required to be filed by AVI with the Securities and
Exchange Commission (the "SEC") under the Securities Exchange Act of 1934, as
amended (the "EXCHANGE ACT"). AVI has furnished to SuperGen copies of its Annual
Report on Form 10-K for the year ended December 31, 1999, and all Current
Reports on Form 8-K and proxy statements, as filed with the SEC. As of the date
filed, the SEC Filings do not contain any untrue statement of a material fact or
omit to state a material fact necessary to make the statements therein, in light
of the circumstances in which they were made, not misleading. The financial
statements contained in the SEC Filings fairly present the financial position of
AVI and its subsidiaries as at the dates thereof and for the periods covered
thereby and have been prepared in accordance with GAAP and with the published
rules and regulations of the SEC with respect thereto.

         3.11 LISTING. AVI Common Stock is duly listed on the Nasdaq National
Market ("NMS"). AVI is not in violation of the listing requirements of the NMS
and does not reasonably anticipate that the AVI Common Stock will be delisted by
the NMS for the foreseeable future.

         3.12 EMPLOYEE BENEFIT PLANS. Except as set forth in the AVI Disclosure
Schedule, all AVI's employee benefit plans comply with and are and have been
operated in accordance with applicable laws and regulations. There are no funded
benefit obligations for which contributions have not been made or properly
accrued and there are no unfunded benefit obligations which have not been
accounted for by reserves on AVI's Financial Statements, and no event has
occurred, and there exists no condition or set of circumstances, with respect to
the employee benefit plans of AVI,

                                      -8-
<PAGE>

which would reasonably be expected to subject AVI to any liability, other than
liabilities which would not be reasonably likely, either individually or in the
aggregate, to have a Material Adverse Effect.

         3.13 EMPLOYEES. To AVI's knowledge, no employee or consultant of AVI is
in material violation of any material term of any such employment or consulting
agreement, confidentiality agreement, or any other contract or agreement
relating to the relationship of such employee or consultant with AVI or any
other party because of the nature of the business conducted or to be conducted
by AVI.

         3.14 BROKERS OR FINDERS. No agent, broker, investment banker, financial
advisor or other firm or person is or will be entitled to any broker's or
finder's fee or any other commission or similar fee in connection with any of
the transactions contemplated by this Agreement or any of the other Transaction
Documents except for a fee of $150,000 and 40,909 shares of AVI Common Stock
paid by AVI to Boston Healthcare for assistance rendered to AVI in partnering
the Avicine vaccine product , and AVI agrees to indemnify and hold SuperGen
harmless from and against any and all claims, liabilities or obligations with
respect to any other fees, commissions or expenses asserted by any person on the
basis of any act or statement alleged to have been made by AVI.

         3.15 COMPLIANCE WITH LAWS. Each of AVI and its subsidiaries has
complied in all material respects with all applicable federal, state, local and
foreign statutes, laws and regulations, and is not in violation of, and has not
received any notices of violation with respect to, any such statute, law or
regulation, with respect to the conduct, ownership or operation of its
businesses which, individually or in aggregate, would have a Material Adverse
Effect. Each of AVI and its subsidiaries has obtained each governmental consent,
license, permit, grant or other authorization of a governmental entity that is
required for the operation of its business as currently conducted (collectively,
the "AVI AUTHORIZATIONS"), and all such AVI Authorizations are in full force and
effect, except for such AVI Authorizations which, if not obtained by AVI or any
of its subsidiaries, would not be reasonably likely, either individually or in
the aggregate, to have a Material Adverse Effect.

         3.16 LITIGATION. Except as set forth in the AVI Disclosure Schedule,
there is no action, suit, proceeding, claim, arbitration or investigation,
pending before any agency, court or tribunal, or to the knowledge of AVI,
threatened against AVI, its subsidiaries or any of their respective properties
or officers or directors (in their capacities as such), and, to the knowledge of
AVI, there is no valid basis for any action, suit, proceeding, claim,
arbitration or investigation against AVI or any of its subsidiaries which, if
determined adversely to AVI or any such subsidiary, would reasonably be expected
to have a Material Adverse Effect. There is no judgment, decree or order against
AVI or any of its subsidiaries or, to the knowledge of AVI after reasonable
inquiry, any of its respective directors or officers (in their capacities as
such) that would prevent, enjoin, or materially alter or delay any of the
transactions contemplated by this Agreement or that would reasonably be expected
to have a Material Adverse Effect.

                                      -9-
<PAGE>

         3.17 NO MISREPRESENTATION. No representation or warranty by AVI in this
Agreement or any of the other Transaction Documents, and no statement,
certificate or schedule furnished or to be furnished by or on behalf of AVI
pursuant to this Agreement or any of the other Transaction Documents, when taken
together, contains any untrue statement of a material fact or omits to state a
material fact required to be stated therein or necessary in order to make such
statements, in light of the circumstances under which they were made, not
misleading.

         3.18 INVESTMENT AVI. AVI is not, and after giving effect to the
issuance of the AVI Shares and the Warrant Shares will not be, an investment
company under the Investment Company Act of 1940.

         3.19 VALID PRIVATE PLACEMENT. Subject to the accuracy of SuperGen's
representations in Section 4.21, AVI is entitled to rely on an AVI exemption
from the provisions of Section 5 of the Securities Act in its sale and issuance
of AVI Shares and Warrant Shares to SuperGen pursuant to the terms of this
Agreement.

         3.20 OREGON BUSINESS CORPORATION ACT. The purchase of the AVI Shares
and Warrant Shares pursuant to this Agreement has been approved by the Board of
Directors of AVI prior to the date of this Agreement for the purposes of the
Oregon Business Corporation Act such that after the date of this Agreement,
neither SuperGen nor any of its affiliates will be subject to the restrictions
on business combination transactions set forth therein with respect to SuperGen
on account of such purchase.

         3.21 EXEMPT OFFERING; ACQUISITION FOR INVESTMENT.

                  3.21.1 AVI is acquiring the SuperGen Shares under this
Agreement solely for AVI's or its designated affiliate's own account for passive
investment purposes and not with a view to, or for resale in connection with,
any distribution thereof within the meaning of the Securities Act of 1933, as
amended (the "SECURITIES ACT"). AVI further represents that AVI does not have
any present intention of selling, offering to sell or otherwise disposing of or
distributing the SuperGen Shares or any portion thereof. AVI acknowledges and
understands that the entire legal and beneficial interest of the SuperGen Shares
AVI is acquiring is being purchased for, and will be held for the account of,
AVI or its designated affiliate only and neither in whole nor in part for any
other person. AVI understands that the SuperGen Shares have not been registered
under the Securities Act or other securities laws in reliance on specific
exemptions therefrom, which exemptions depend upon, among other things, the bona
fide nature of AVI investment intent as expressed herein.

                  3.21.2 The SuperGen Shares were not offered to AVI through,
and AVI is not aware of, any form of general solicitation or general
advertising, including, without limitation, (i) any advertisement, article,
notice or other communication published in any newspaper, magazine or similar
media or broadcast over television or radio, and (ii) any seminar or meeting
whose attendees have been invited by any general solicitation or general
advertising.

                                      -10-
<PAGE>

                  3.21.3 AVI is an "accredited" investor as defined in
Regulation D under the Securities Act, and a "qualified institutional buyer"
within the meaning of Rule 144A under the Securities Act.

                  3.21.4 AVI further acknowledges and understands that the
SuperGen Shares must be held indefinitely unless they are subsequently
registered under the Securities Act or an exemption from such registration is
available, and the transfer complies with the restrictions set forth in Section
5.5 of this Agreement. AVI understands that the certificate(s) evidencing the
SuperGen Shares will be imprinted with a legend that sets forth the restrictions
on transfer.

                  3.21.5 AVI understands that Rule 144 promulgated under the
Securities Act permits limited resale of shares purchased in a private placement
subject to the satisfaction of certain conditions, including, among other
things, the existence of a public market for the SuperGen Shares, the
availability of certain current public information about SuperGen, more than one
year having elapsed between the resale and the date the security to be sold was
last held by SuperGen or an affiliate of SuperGen, the sale being made through a
"broker's transaction" or in transactions directly with a "market maker," and
the number of shares being sold during any three-month period not exceeding
specified limitations. AVI is further aware that Rule 144(k) permits persons who
have not been affiliates of SuperGen for at least three months and whose shares
have been beneficially owned by a person other than SuperGen or its affiliates
for at least two years after full payment for such shares to sell such shares
without regard to the current public information, manner of sale and volume
limitations described above.

                  3.21.6 AVI has reviewed with its own tax advisers the federal,
state, and local tax consequences of this investment and the transactions
contemplated by this Agreement and has relied solely on such advisers and not on
any statements or representations of SuperGen or any of its agents other than
the representations and warranties set forth herein. AVI understands that it
(and not SuperGen) shall be responsible for its own tax liability that may arise
as a result of its investment or the transactions contemplated by this
Agreement.

         3.22 ACCESS TO INFORMATION; INVESTMENT EXPERIENCE; NO RELIANCE.

                  3.22.1 ACCESS TO INFORMATION. AVI has, prior to the date of
this Agreement, been furnished with SuperGen's most recent SEC Filings and given
an opportunity to review material contracts and documents of SuperGen which have
been filed as exhibits to such SEC Filings. AVI has had opportunity to discuss
SuperGen's business, management and financial affairs with its management. AVI
has also had an opportunity to ask questions of officers of SuperGen, which
questions were answered to its satisfaction. AVI, in making the investment
decision, has read, reviewed, and relied solely on SuperGen's SEC Filings and
other documents furnished by SuperGen, including SuperGen's Financial
Statements, pursuant to this Agreement and SuperGen's representations and
warranties contained herein, and has made an independent investigation, or
obtained any additional information which AVI deems necessary to verify the
accuracy and

                                      -11-
<PAGE>

completeness of the information received. AVI is not relying on any oral
representation of SuperGen or any other person, nor any written representation
or assurance from SuperGen other than those contained in the SEC Filings or
incorporated herein or therein. The foregoing, however, does not limit or modify
AVI's right to rely upon covenants, representations and warranties of SuperGen
in Section 4 of this Agreement. AVI acknowledges and agrees that SuperGen has no
responsibility for, does not ratify, and is under no responsibility whatsoever
to comment upon or correct any reports, analyses or other comments made about
SuperGen by any third parties, including, but not limited to, analysts' research
reports or comments, and AVI has not relied upon any such third party reports in
making the decision to invest.

                  3.22.2 RISK OF INVESTMENT; INVESTMENT EXPERIENCE; CAPABILITY
TO EVALUATE. AVI recognizes that an investment in SuperGen involves substantial
risks, including the potential loss of AVI's entire investment herein. AVI has
substantial knowledge and experience in investing in securities and in financial
and business matters that it is capable of evaluating the merits and risks of
the investment. AVI acknowledges that it is able to fend for itself in the
transactions contemplated by this Agreement, and that AVI has the ability to
bear the economic risk of investment pursuant to this Agreement.

                  3.22.3 RELIANCE ON OWN JUDGEMENT OR ADVISORS. AVI has relied
completely on its own judgement or the advice of its own tax, investment, legal
or other advisors and has not relied on SuperGen or any of its affiliates,
officers, directors, attorneys, accountants or any affiliates of any thereof and
each other person, if any, who controls any of the foregoing, within the meaning
of Section 15 of the Securities Act for any tax, investment or legal advice
(other than reliance on information furnished by SuperGen, the representations,
warranties and covenants contained herein).

                                    SECTION 4
                   REPRESENTATIONS AND WARRANTIES OF SUPERGEN

         Except as disclosed in SuperGen's SEC Filings or as set forth in the
disclosure schedule previously provided to AVI (the "SUPERGEN DISCLOSURE
SCHEDULE"), SuperGen hereby represents and warrants to and agrees with AVI as
follows:

         4.1 ORGANIZATION; STANDING AND POWER; QUALIFICATION. SuperGen and each
of its subsidiaries is a corporation duly organized and existing under, and by
virtue of, the laws of the State of Delaware and is in good standing under such
laws. SuperGen and each of its subsidiaries have all requisite corporate power
to own, lease and operate its property and to carry on its businesses, and is
duly qualified to do business and is in good standing as a foreign corporation
in any jurisdiction except where the failure to be so qualified and in good
standing would not have a material adverse effect on the business, assets
(including intangible assets), properties, liabilities (contingent or
otherwise), financial condition, operations, or results of operation of SuperGen
or its subsidiaries, taken as a whole (a "MATERIAL ADVERSE EFFECT").

                                      -12-
<PAGE>

         4.2 CAPITALIZATION. The authorized capital stock of SuperGen consists
of 40,000,000 shares of SuperGen Common Stock, $0.001 par value, and 2,000,000
shares of preferred stock, $0.001 par value. As of March 31, 2000, there were
30,555,785 shares of SuperGen Common Stock issued and outstanding, 3,192,316 of
SuperGen Common Stock issuable under SuperGen's stock option plans and 5,106,067
shares issuable pursuant to warrants and there were no issued and outstanding
shares of preferred stock. All such issued and outstanding shares have been duly
authorized and validly issued, are fully paid and nonassessable. Except as set
forth in the SuperGen Disclosure Schedule, no shares of SuperGen Common Stock
are entitled to preemptive rights or registration rights and there are no
outstanding options, warrants, scrip, rights to subscribe to, call or
commitments of any character whatsoever relating to, or securities or rights
convertible into, any shares of capital stock of SuperGen. Furthermore, except
as set forth in this Agreement and the SuperGen Disclosure Schedule, there are
no contracts or commitments by which SuperGen is or may become bound to issue
additional shares of the capital stock of SuperGen or options, securities or
rights convertible into shares of capital stock of SuperGen. SuperGen is not a
party to, and it has no knowledge of, any agreement restricting the voting or
transfer of any shares of the capital stock of SuperGen other than transfer
restrictions imposed to satisfy state and federal securities laws. Except as set
forth in the SuperGen Disclosure Schedule, the offer and sale of all capital
stock, convertible securities, rights, warrants, or options of SuperGen issued
prior to the Closing and any Subsequent Closing complied with all applicable
federal and state securities laws. Each of SuperGen's subsidiaries is
wholly-owned by SuperGen.

         4.3      AUTHORIZATION; NO CONFLICTS; APPROVALS.

                  4.3.1 All corporate action on the part of SuperGen, its
stockholders and its directors necessary for the authorization, execution,
delivery and performance of the Agreement by SuperGen, the authorization, sale,
issuance and delivery of the SuperGen Shares, and the performance of all of
SuperGen's obligations under the Agreement has been taken or will be taken prior
to the Closing Date or Subsequent Closing Date. The Agreement, the Registration
Rights Agreement and any other documents required to be executed and delivered
by SuperGen hereunder (collectively, the "TRANSACTION DOCUMENTS"), when executed
and delivered by SuperGen, shall constitute valid and binding obligations of
SuperGen, enforceable in accordance with their terms, subject to laws of general
application relating to bankruptcy, insolvency and the relief of debtors and
rules of law governing specific performance, injunctive relief or other
equitable remedies. The SuperGen Shares, when issued in compliance with the
provisions of this Agreement, will be validly issued, fully paid and
nonassessable, and free of any liens or encumbrances, other than any permissible
liens or encumbrances created by or imposed upon the SuperGen Shares by AVI;
provided, however, that the SuperGen Shares are subject to restrictions on
transfer under state and/or federal securities laws and as set forth in this
Agreement.

                  4.3.2 The execution and delivery by SuperGen of this Agreement
and the other Transaction Documents do not, and the consummation of the
transactions contemplated hereby and thereby will not, (i) conflict with, or
result in any violation of or breach of any provision of the

                                      -13-
<PAGE>

Certificate of Incorporation or Bylaws of SuperGen, (ii) result in any violation
or breach of, or constitute (with or without notice or lapse of time, or both) a
default under, or give rise to a right of termination, cancellation or
acceleration of any obligation or loss of any benefit under any license,
assignment, note, mortgage, indenture, lease, contract or other agreement or
obligation to which SuperGen is a party or by which SuperGen or any of its
properties or assets may be bound, (iii) conflict with or violate any judgment,
order, decree, statute, law, ordinance, rule or regulation or any material
permit, concession, franchise or license applicable to SuperGen or any of its
properties or assets, except in the case of (ii) for such violations, breaches,
defaults, rights of termination, cancellation or acceleration, or losses of
benefits which would not be reasonably likely to have a Material Adverse Effect.

                  4.3.3 No consent, approval, order or authorization of, or
registration, declaration or filing with, any governmental entity is required by
or with respect to SuperGen in connection with the execution and delivery of
this Agreement and the other Transaction Documents or the consummation of the
transactions contemplated hereby or thereby, except that the filing of one or
more notification and report forms under the HSR Act may be required with
respect to the acquisition by AVI of the SuperGen Shares, and except (i) such
other consents, approvals, orders, authorizations, registrations, declarations
and filings as may be required under applicable federal and state securities
laws and the laws of any foreign country, and (ii) such other consents,
authorizations, filings, approvals and registrations which, if not obtained or
made, would not be reasonably likely to have a Material Adverse Effect.

         4.4 FINANCIAL STATEMENTS. SuperGen has delivered to AVI copies of
SuperGen's audited consolidated financial statements (balance sheet, statement
of operations, statement of stockholders' equity, and statement of cash flows)
for the year ended December 31, 1999 (the "SUPERGEN FINANCIAL STATEMENTS").
SuperGen Financial Statements were prepared in accordance with GAAP applied on a
consistent basis throughout the periods involved (except as may be otherwise
indicated in such financial statements or the notes thereto). SuperGen Financial
Statements present fairly in all material respects the financial position of
SuperGen and its subsidiaries as of the respective dates and the consolidated
results of its operations and cash flows for the periods indicated.

         4.5 ABSENCE OF UNDISCLOSED LIABILITIES. Neither SuperGen nor any of its
subsidiaries has any liabilities, either accrued or contingent (whether or not
required to be reflected in financial statements in accordance with GAAP), and
whether due or to become due, other than (i) liabilities reflected or provided
for on the balance sheet as of December 31, 1999 (the "SUPERGEN BALANCE SHEET")
contained in SuperGen Financial Statements, (ii) liabilities specifically
described in this Agreement or the SuperGen Disclosure Schedule, and (iii)
normal or recurring liabilities incurred since December 31, 1999 in the ordinary
course of business consistent with past practices that would not reasonably be
expected to result in a Material Adverse Effect.

         4.6 ABSENCE OF CERTAIN CHANGES OR EVENTS. Except as set forth in the
SuperGen Disclosure Schedule, and except as reflected in SuperGen Financial
Statements, since December 31,

                                      -14-
<PAGE>

1999, SuperGen and its subsidiaries have conducted their businesses in the
ordinary course and in a manner consistent with past practices, and have not:

                  4.6.1 suffered any event or occurrence that has had or would
reasonably be expected to have a Material Adverse Effect;

                  4.6.2 declared, set aside or paid any dividend or made any
other distribution on or in respect of the shares of its capital stock or
declared any direct or indirect redemption, retirement, purchase or other
acquisition of such shares, except for purchases of stock from terminated
non-officer employees in the ordinary course of business and in a manner
consistent with past practices;

                  4.6.3 issued any shares of their capital stock or any
warrants, rights, or options for, or entered into any commitment relating to
such capital stock, except for issuances made in the ordinary course of business
in arm's length transactions for value and in a manner consistent with past
practices (including issuances made upon exercises and conversions of employee
and director stock options);

                  4.6.4 made any material change in the accounting methods or
practices they follow, whether for general financial or tax purposes, or any
change in depreciation or amortization policies or rates;

                  4.6.5 bought, rented, sold, leased, abandoned or otherwise
disposed of any real property or machinery, equipment or other operating
property except in the ordinary course of business and in a manner consistent
with past practices and in an amount that is not material to SuperGen and its
subsidiaries taken as a whole;

                  4.6.6 sold, assigned, transferred, licensed, pledged, or
otherwise disposed of or encumbered any patent, trademark, trade name, brand
name, the FDA license or approval application, copyright (or pending application
for any patent, trademark or copyright), invention, work of authorship, process,
know-how, formula or trade secret or interest thereunder or other material
intangible asset, except for non-exclusive licenses which were granted in the
ordinary course of business and in a manner consistent with past practices and
in an amount that is not material to SuperGen and its subsidiaries taken as a
whole;

                  4.6.7 entered into any material commitment or transaction
(including without limitation any borrowing or capital expenditure) other than
the transactions contemplated by this Agreement and the other Transaction
Documents; or

                  4.6.8 paid, loaned or advanced any amount to, or sold,
transferred or leased any properties or assets or rights under license to, or
entered into any agreement or arrangement with any of its officers, directors or
stockholders or any affiliate of any of the foregoing, other than employee

                                      -15-
<PAGE>

compensation and benefits and reimbursement of employment related business
expenses incurred in the ordinary course of business.

         4.7 TAXES. SuperGen (including its subsidiaries) has timely made or
filed all federal and state income and all other tax returns, reports and
declarations required by any jurisdiction to which it is subject and has paid
all taxes and other governmental assessments and charges, shown or determined to
be due on such returns, reports and declarations, except those being contested
in good faith and has set aside on its books provision reasonably adequate for
the payment of all taxes for periods subsequent to the periods to which such
returns, reports or declarations apply. There are no material unpaid taxes
claimed to be due by the taxing authority of any jurisdiction, and the officers
of SuperGen know of no basis for any such claim. To the best knowledge of
SuperGen, there are no pending or proposed audits or claims from any tax
authority for deficiencies, penalties or interest against SuperGen or its
subsidiaries and the officers of SuperGen know of no basis for any such audit or
claim

         4.8 INTELLECTUAL PROPERTY. To SuperGen's knowledge after reasonable
inquiry, (i) each of SuperGen and its subsidiaries has the right to use, free
and clear of all liens, charges, claims and restrictions, all intellectual
property, patents, trademarks, service marks, trade names, copyrights, licenses
and rights which are material to its business as presently conducted and (ii)
neither SuperGen nor any of its subsidiaries is infringing upon or otherwise
acting adversely to the right or claimed right of any other person under or with
respect to the foregoing.

         4.9 ENVIRONMENTAL MATTERS. To SuperGen's knowledge after reasonable
inquiry, neither SuperGen nor any of its subsidiaries is in violation of any
Environmental Laws which, individually or in aggregate, would have a Material
Adverse Effect. Except as set forth in the SuperGen Disclosure Schedule, to
SuperGen's knowledge after reasonable inquiry, neither SuperGen nor any of its
subsidiaries owns or operates any real property contaminated with any substance
that is subject to any Environmental Laws, is liable for any off-site disposal
or contamination pursuant to any Environmental Laws, or is subject to any claim
relating to any Environmental Laws, which violation, contamination, liability or
claim would individually or in aggregate have a Material Adverse Effect; and
SuperGen is not aware of any pending investigation that might lead to such a
claim.

         4.10 SEC FILINGS. SuperGen has timely filed all SEC Filings required to
be filed by SuperGen with the SEC under the Exchange Act. SuperGen has furnished
to AVI copies of its Annual Report on Form 10-K for the year ended December 31,
1999 and all Current Reports on Form 8-K and proxy statements, as filed with the
SEC. As of the date filed, the SEC Filings do not contain any untrue statement
of a material fact or omit to state a material fact necessary to make the
statements therein, in light of the circumstances in which they were made, not
misleading. The financial statements contained in the SEC Filings fairly present
the financial position of SuperGen and its subsidiaries as at the dates thereof
and for the periods covered thereby and have been

                                      -16-
<PAGE>

prepared in accordance with GAAP and with the published rules and regulations of
the SEC with respect thereto.

         4.11 LISTING. SuperGen's Common Stock is duly listed on the NMS.
SuperGen is not in violation of the listing requirements of the NMS and does not
reasonably anticipate that the SuperGen Common Stock will be delisted by the NMS
for the foreseeable future.

         4.12 EMPLOYEE BENEFIT PLANS. Except as set forth in the SuperGen
Disclosure Schedule, all SuperGen's employee benefit plans comply with and are
and have been operated in accordance with applicable laws and regulations. There
are no funded benefit obligations for which contributions have not been made or
properly accrued and there are no unfunded benefit obligations which have not
been accounted for by reserves on SuperGen's Financial Statements, and no event
has occurred, and there exists no condition or set of circumstances, with
respect to the employee benefit plans of SuperGen, which would reasonably be
expected to subject SuperGen to any liability, other than liabilities which
would not be reasonably likely, either individually or in the aggregate, to have
a Material Adverse Effect.

         4.13 EMPLOYEES. To SuperGen's knowledge, no employee or consultant of
SuperGen is in material violation of any material term of any such employment or
consulting agreement, confidentiality agreement, or any other contract or
agreement relating to the relationship of such employee or consultant with
SuperGen or any other party because of the nature of the business conducted or
to be conducted by SuperGen.

         4.14 BROKERS OR FINDERS. No agent, broker, investment banker, financial
advisor or other firm or person is or will be entitled to any broker's or
finder's fee or any other commission or similar fee in connection with any of
the transactions contemplated by this Agreement or any of the other Transaction
Documents, and SuperGen agrees to indemnify and hold AVI harmless from and
against any and all claims, liabilities or obligations with respect to any other
fees, commissions or expenses asserted by any person on the basis of any act or
statement alleged to have been made by SuperGen.

         4.15 COMPLIANCE WITH LAWS. Each of SuperGen and its subsidiaries has
complied in all material respects with all applicable federal, state, local and
foreign statutes, laws and regulations, and is not in violation of, and has not
received any notices of violation with respect to, any such statute, law or
regulation, with respect to the conduct, ownership or operation of its
businesses which, individually or in aggregate, would have a Material Adverse
Effect. Each of SuperGen and its subsidiaries has obtained each governmental
consent, license, permit, grant or other authorization of a governmental entity
that is required for the operation of its business as currently conducted
(collectively, the "SUPERGEN AUTHORIZATIONS"), and all SuperGen Authorizations
are in full force and effect, except for such Company Authorizations which, if
not obtained by SuperGen or any of its subsidiaries, would not be reasonably
likely, either individually or in the aggregate, to have a Material Adverse
Effect.

                                      -17-
<PAGE>

         4.16 LITIGATION. Except as set forth in the SuperGen Disclosure
Schedule, there is no action, suit, proceeding, claim, arbitration or
investigation, pending before any agency, court or tribunal, or to the knowledge
of SuperGen, threatened against SuperGen, its subsidiaries or any of their
respective properties or officers or directors (in their capacities as such),
and, to the knowledge of SuperGen, there is no valid basis for any action, suit,
proceeding, claim, arbitration or investigation against SuperGen or any of its
subsidiaries which, if determined adversely to SuperGen or any such subsidiary,
would reasonably be expected to have a Material Adverse Effect. There is no
judgment, decree or order against SuperGen or any of its subsidiaries or, to the
knowledge of SuperGen after reasonable inquiry, any of its respective directors
or officers (in their capacities as such) that would prevent, enjoin, or
materially alter or delay any of the transactions contemplated by this Agreement
or that would reasonably be expected to have a Material Adverse Effect.

         4.17 NO MISREPRESENTATION. No representation or warranty by SuperGen in
this Agreement or any of the other Transaction Documents, and no statement,
certificate or schedule furnished or to be furnished by or on behalf of SuperGen
pursuant to this Agreement or any of the other Transaction Documents, when taken
together, contains any untrue statement of a material fact or omits to state a
material fact required to be stated therein or necessary in order to make such
statements, in light of the circumstances under which they were made, not
misleading.

         4.18 INVESTMENT COMPANY. SuperGen is not, and after giving effect to
the issuance of the SuperGen Shares will not be, an investment company under the
Investment Company Act of 1940.

         4.19 VALID PRIVATE PLACEMENT. Subject to the accuracy of AVI's
representations in Section 3.21, SuperGen is entitled to rely on an exemption
from the provisions of Section 5 of the Securities Act in its sale and issuance
of the SuperGen Shares to AVI pursuant to the terms of this Agreement.

         4.20 SECTION 203. The purchase of the SuperGen Shares pursuant to this
Agreement has been approved by the Board of Directors of SuperGen prior to the
date of this Agreement for the purposes of Section 203 of the Delaware General
Corporation Law such that after the date of this Agreement, neither AVI nor any
of its affiliates will be subject to the restrictions on business combination
transactions set forth in said Section 203 with respect to SuperGen on account
of such purchase.

         4.21 EXEMPT OFFERING; ACQUISITION FOR INVESTMENT.

                  4.21.1 SuperGen is acquiring the AVI Shares and Warrant Shares
solely for SuperGen's or its designated affiliate's own account for passive
investment purposes and not with a view to, or for resale in connection with,
any distribution thereof within the meaning of the Securities Act. SuperGen
further represents that SuperGen does not have any present intention of selling,
offering to sell or otherwise disposing of or distributing the AVI Shares or
Warrant Shares or any portion thereof. SuperGen acknowledges and understands
that the entire legal and beneficial

                                      -18-
<PAGE>

interest of the AVI Shares and Warrant Shares SuperGen is acquiring is being
purchased for, and will be held for the account of, SuperGen or its designated
affiliate only and neither in whole nor in part for any other person. SuperGen
understands that the AVI Shares and Warrant Shares have not been registered
under the Securities Act or other securities laws in reliance on specific
exemptions therefrom, which exemptions depend upon, among other things, the bona
fide nature of SuperGen's investment intent as expressed herein.

                  4.21.2 The AVI Shares and Warrant Shares were not offered to
SuperGen through, and SuperGen is not aware of, any form of general solicitation
or general advertising, including, without limitation, (i) any advertisement,
article, notice or other communication published in any newspaper, magazine or
similar media or broadcast over television or radio, and (ii) any seminar or
meeting whose attendees have been invited by any general solicitation or general
advertising.

                  4.21.3 SuperGen is an "accredited" investor as defined in
Regulation D under the Securities Act, and a "qualified institutional buyer"
within the meaning of Rule 144A under the Securities Act.

                  4.21.4 SuperGen further acknowledges and understands that the
AVI Shares and Warrant Shares must be held indefinitely unless they are
subsequently registered under the Securities Act or an exemption from such
registration is available, and the transfer complies with the restrictions set
forth in Section 5.5 of this Agreement. SuperGen understands that the
certificate(s) evidencing the AVI Shares and Warrant Shares will be imprinted
with a legend that sets forth the restrictions on transfer.

                  4.21.5 SuperGen understands that Rule 144 promulgated under
the Securities Act permits limited resale of shares purchased in a private
placement subject to the satisfaction of certain conditions, including, among
other things, the existence of a public market for the AVI Shares and Warrant
Shares, the availability of certain current public information about AVI, more
than one year having elapsed between the resale and the date the security to be
sold was last held by AVI or an affiliate of AVI, the sale being made through a
"broker's transaction" or in transactions directly with a "market maker," and
the number of shares being sold during any three-month period not exceeding
specified limitations. SuperGen is further aware that Rule 144(k) permits
persons who have not been affiliates of AVI for at least three months and whose
shares have been beneficially owned by a person other than AVI or its affiliates
for at least two years after full payment for such shares to sell such shares
without regard to the current public information, manner of sale and volume
limitations described above.

                  4.21.6 SuperGen has reviewed with its own tax advisers the
federal, state, and local tax consequences of this investment and the
transactions contemplated by this Agreement and has relied solely on such
advisers and not on any statements or representations of AVI or any of its
agents other than the representations and warranties set forth herein. SuperGen
understands that it

                                      -19-
<PAGE>

(and not AVI) shall be responsible for its own tax liability that may arise as a
result of this investment or the transactions contemplated by this Agreement.

         4.22 ACCESS TO INFORMATION; INVESTMENT EXPERIENCE; NO RELIANCE.

                  4.22.1 ACCESS TO INFORMATION. SuperGen has, prior to the date
of this Agreement, been furnished with AVI's most recent SEC Filings and given
an opportunity to review material contracts and documents of AVI which have been
filed as exhibits to such SEC Filings. SuperGen has had opportunity to discuss
AVI's business, management and financial affairs with its management. SuperGen
has also had an opportunity to ask questions of officers of AVI, which questions
were answered to its satisfaction. SuperGen, in making the investment decision,
has read, reviewed, and relied solely on AVI's SEC Filings and other documents
furnished by AVI, including AVI's Financial Statements, pursuant to this
Agreement and AVI's representations and warranties contained herein, and has
made an independent investigation, or obtained any additional information which
SuperGen deems necessary to verify the accuracy and completeness of the
information received. SuperGen is not relying on any oral representation of AVI
or any other person, nor any written representation or assurance from AVI other
than those contained in the SEC Filings or incorporated herein or therein. The
foregoing, however, does not limit or modify SuperGen's right to rely upon
covenants, representations and warranties of AVI in Section 3 of this Agreement.
SuperGen acknowledges and agrees that AVI has no responsibility for, does not
ratify, and is under no responsibility whatsoever to comment upon or correct any
reports, analyses or other comments made about AVI by any third parties,
including, but not limited to, analysts' research reports or comments, and
SuperGen has not relied upon any such third party reports in making the decision
to invest.

                  4.22.2 RISK OF INVESTMENT; INVESTMENT EXPERIENCE; CAPABILITY
TO EVALUATE. SuperGen recognizes that an investment in AVI involves substantial
risks, including the potential loss of SuperGen's entire investment herein.
SuperGen has substantial knowledge and experience in investing in securities and
in financial and business matters that it is capable of evaluating the merits
and risks of the investment. SuperGen acknowledges that it is able to fend for
itself in the transactions contemplated by this Agreement, and that SuperGen has
the ability to bear the economic risk of investment pursuant to this Agreement.

                  4.22.3 RELIANCE ON OWN JUDGEMENT OR ADVISORS. SuperGen has
relied completely on its own judgement or the advice of its own tax, investment,
legal or other advisors and has not relied on AVI or any of its affiliates,
officers, directors, attorneys, accountants or any affiliates of any thereof and
each other person, if any, who controls any of the foregoing, within the meaning
of Section 15 of the Securities Act for any tax, investment or legal advice
(other than reliance on information furnished by AVI, the representations,
warranties and covenants contained herein).

         4.23 BROKERS OR FINDERS. No agent, broker, investment banker, financial
adviser or other firm or person is or will be entitled to any broker's or
finder's fee, or any other commission or

                                      -20-
<PAGE>

similar fee, in connection with any of the transactions contemplated by this
Agreement or any of the other Transaction Documents, and SuperGen agrees to
indemnify and hold AVI and its subsidiaries harmless from and against any and
all claims, liabilities or obligations with respect to any such fees or
commissions asserted by any person on the basis of any act or statement
determined to have been made to such person by SuperGen.

                                    SECTION 5

                              ADDITIONAL AGREEMENTS

         AVI and SuperGen further agree with each other as follows:

         5.1      FINANCIAL STATEMENTS AND OTHER REPORTS.

                  5.1.1 As long as SuperGen beneficially owns, either outright
or pursuant to rights to acquire, at least five percent (5%) of AVI Common Stock
on either a primary or fully diluted basis, AVI shall deliver to SuperGen,
promptly after transmission thereof, copies of all such financial statements,
proxy statements, notices and reports as AVI shall send to its public
shareholders and copies of all registration statements (without exhibits), other
than registration statements on Form S-8 or any similar successor form, and all
reports which it files with the SEC (or any governmental body or agency
succeeding to the functions of the SEC). SuperGen shall have the right to
discuss such financial statements, proxy statements, notices, reports,
registration statements and filings with such officers of AVI as SuperGen may
reasonably designate upon reasonable notice and at reasonable times, and to
share such information with SuperGen's professional advisers, subject to the
confidentiality provisions set forth in Section 5.2.

                  5.1.2 As long as AVI beneficially owns, either outright or
pursuant to rights to acquire, at least five percent (5%) of SuperGen Common
Stock on either a primary or fully diluted basis, SuperGen shall deliver to AVI,
promptly after transmission thereof, copies of all such financial statements,
proxy statements, notices and reports as SuperGen shall send to its public
stockholders and copies of all registration statements (without exhibits), other
than registration statements on Form S-8 or any similar successor form, and all
reports which it files with the SEC (or any governmental body or agency
succeeding to the functions of the SEC). SuperGen shall have the right to
discuss such financial statements, proxy statements, notices, reports,
registration statements and filings with such officers of SuperGen as AVI may
reasonably designate upon reasonable notice and at reasonable times, and to
share such information with AVI's professional advisers, subject to the
confidentiality provisions set forth in Section 5.2.

         5.2 CONFIDENTIALITY. Except as permitted by Section 5.3, each party
agrees (and shall cause its professional advisers to agree) not to disclose to
any person any information or data obtained by them pursuant to Section 5.1
until such information or data otherwise becomes publicly available or except
pursuant to a valid subpoena, judicial process or its equivalent or as otherwise

                                      -21-
<PAGE>

required by law. At the disclosing party's request, the receiving party shall,
and shall cause its professional advisers to, sign a confidentiality agreement,
in form and substance reasonably satisfactory to the disclosing party, as a
condition to the receipt of confidential nonpublic information of the disclosing
party by such advisers pursuant to Section 5.1.

         5.3 PUBLIC ANNOUNCEMENTS. Each of the parties hereto will cooperate
with each other in the development and distribution of all news releases and
other public information disclosures with respect to this Agreement and the
other Transaction Documents and any of the transactions contemplated hereby and
thereby, and neither party hereto directly or indirectly through its officers
and/or directors shall make any further announcement, news release or disclosure
without first consulting with the other party hereto except (a) with the prior
written consent of the other party or (b) to the extent such party believes in
good faith, after consultation with legal counsel, that such announcement,
release or disclosure is required by law. Each party shall not, and shall cause
its officers and directors not to, make or contribute to any public statement,
news release or other public communication or filing disclosing personal
information concerning the other party or any member of the other party without
the prior written consent of the other party and such member unless such party
believes in good faith, after consultation with legal counsel, that such
statement, release, communication or filing is required by law.

         5.4 HSR ACT. AVI shall be responsible for all applicable filing fees
under the HSR Act ") relating to the acquisition of AVI Shares and Warrant
Shares, and SuperGen shall be responsible for all applicable filing fees under
the HSR Act relating to the acquisition of SuperGen Shares. Each party shall use
its best efforts to cooperate with the other party in making the applicable
filings under the HSR Act, and with respect to the exercise of the Warrant,
SuperGen agrees not to exercise the Warrant on any date prior to the expiration
or early termination of the applicable waiting periods under the HSR Act.

         5.5      RESTRICTIONS ON TRANSFER.

                  5.5.1 SuperGen shall not, directly or indirectly, sell,
transfer, assign, pledge, distribute or otherwise dispose of, or grant any
option with respect to, establish any "short" or put-equivalent position with
respect to, or otherwise enter into any agreement, arrangement, transaction or
series of transactions (through derivatives or otherwise) which has or is
intended to have the effect, directly or indirectly, of reducing SuperGen's risk
of ownership in the AVI Shares or Warrant Shares it purchases pursuant to this
Agreement (each of the foregoing, a "Transfer") unless the Transfer is effected
pursuant to (a) a registration statement under the Securities Act and any
applicable state securities laws or (b) an exemption from the registration
requirements under federal and state securities laws, and AVI receives an
opinion of counsel, reasonably satisfactory to AVI stating that such Transfer
will not require registration of the AVI Shares or the Warrant Shares, as the
case may be, under the Securities Act or state securities laws, except that such
an opinion will not be required for transactions made pursuant to Rule 144
provided that SuperGen and SuperGen's

                                      -22-
<PAGE>

broker, if necessary, provide AVI with the necessary representations for counsel
to AVI to issue an opinion with respect to such transaction.

                  5.5.2 AVI shall not, directly or indirectly, make a Transfer
of the SuperGen Shares it purchases pursuant to this Agreement unless the
Transfer is effected pursuant to (a) a registration statement under the
Securities Act and any applicable state securities laws or (b) an exemption from
the registration requirements under federal and state securities laws, and
SuperGen receives an opinion of counsel, reasonably satisfactory to SuperGen
stating that such Transfer will not require registration of the SuperGen Shares,
under the Securities Act or state securities laws, except that such an opinion
will not be required for transactions made pursuant to Rule 144 provided that
AVI and AVI's broker, if necessary, provide SuperGen with the necessary
representations for counsel to SuperGen to issue an opinion with respect to such
transaction.

         5.6      LEGENDS.

                  5.6.1 Each certificate representing the AVI Shares and Warrant
Shares shall be endorsed with the following legends, and any other legends
required by law:

         THE SECURITIES EVIDENCED BY THIS CERTIFICATE HAVE NOT BEEN REGISTERED
         UNDER THE SECURITIES ACT OF 1933, AS AMENDED, AND MAY NOT BE SOLD,
         TRANSFERRED, ASSIGNED OR HYPOTHECATED UNLESS THERE IS AN EFFECTIVE
         REGISTRATION STATEMENT UNDER SUCH ACT COVERING SUCH SECURITIES, THE
         SALE IS MADE IN ACCORDANCE WITH RULE 144 UNDER THE ACT, OR AVI RECEIVES
         AN OPINION OF COUNSEL FOR THE HOLDER OF THESE SECURITIES REASONABLY
         SATISFACTORY TO AVI, STATING THAT SUCH SALE, TRANSFER, ASSIGNMENT OR
         HYPOTHECATION IS EXEMPT FROM THE REGISTRATION AND PROSPECTUS DELIVERY
         REQUIREMENTS OF SUCH ACT.

         THE SECURITIES EVIDENCED BY THIS CERTIFICATE ARE SUBJECT TO
         RESTRICTIONS ON TRANSFER SET FORTH IN AN AGREEMENT DATED AS OF APRIL 4,
         2000, BY AND BETWEEN SUPERGEN, INC. AND AVI BIOPHARMA, INC., A COPY OF
         WHICH AGREEMENT MAY BE OBTAINED AT NO COST BY WRITTEN REQUEST MADE BY
         THE HOLDER OF RECORD OF THIS CERTIFICATE TO THE SECRETARY OF AVI
         BIOPHARMA, INC. AT AVI BIOPHARMA, INC.'S PRINCIPAL EXECUTIVE OFFICES.

         AVI need not register a transfer of the legended AVI Shares or Warrant
Shares, and may also instruct its transfer agent not to register the transfer of
such AVI Shares or Warrant Shares, as the case may be, unless the conditions
specified in each of the foregoing legends are satisfied. The first of the
foregoing legends shall be removed from any security legended

                                      -23-
<PAGE>

pursuant to this Section 5.6.1, and AVI shall issue a certificate without such
legend to the holder of such AVI Shares or Warrant Shares, as the case may be,
if such AVI Shares or Warrant Shares are registered under the Securities Act and
a prospectus meeting the requirements of Section 10 of the Securities Act is
available or if such holder satisfies the requirements of Rule 144(k), or the
holder provides AVI with an opinion of counsel, reasonably satisfactory to AVI,
to the effect that a public sale, transfer or assignment of such AVI Shares or
Warrant Shares may be made without registration. The second of the foregoing
legends shall be removed from any AVI Shares or Warrant Shares legended in
accordance with this Section 5.6.1, and AVI shall issue a certificate without
such legend to the holder of such AVI Share or Warrant Share at such time as
such share is transferred in accordance with Section 5.5. The stop transfer
instructions with respect to any legended share shall be removed if both of the
foregoing legends are removed in accordance with this Section 5.6.1.

                  5.6.2 Each certificate representing the SuperGen Shares shall
be endorsed with the following legends, and any other legends required by law:

         THE SECURITIES EVIDENCED BY THIS CERTIFICATE HAVE NOT BEEN REGISTERED
         UNDER THE SECURITIES ACT OF 1933, AS AMENDED, AND MAY NOT BE SOLD,
         TRANSFERRED, ASSIGNED OR HYPOTHECATED UNLESS THERE IS AN EFFECTIVE
         REGISTRATION STATEMENT UNDER SUCH ACT COVERING SUCH SECURITIES, THE
         SALE IS MADE IN ACCORDANCE WITH RULE 144 UNDER THE ACT, OR SUPERGEN
         RECEIVES AN OPINION OF COUNSEL FOR THE HOLDER OF THESE SECURITIES
         REASONABLY SATISFACTORY TO SUPERGEN, STATING THAT SUCH SALE, TRANSFER,
         ASSIGNMENT OR HYPOTHECATION IS EXEMPT FROM THE REGISTRATION AND
         PROSPECTUS DELIVERY REQUIREMENTS OF SUCH ACT.

         THE SECURITIES EVIDENCED BY THIS CERTIFICATE ARE SUBJECT TO
         RESTRICTIONS ON TRANSFER SET FORTH IN AN AGREEMENT DATED AS OF APRIL 4,
         2000, BY AND BETWEEN SUPERGEN, INC. AND AVI BIOPHARMA, INC., A COPY OF
         WHICH AGREEMENT MAY BE OBTAINED AT NO COST BY WRITTEN REQUEST MADE BY
         THE HOLDER OF RECORD OF THIS CERTIFICATE TO THE SECRETARY OF SUPERGEN,
         INC. AT SUPERGEN, INC.'S PRINCIPAL EXECUTIVE OFFICES.

         SuperGen need not register a transfer of the legended SuperGen Shares,
and may also instruct its transfer agent not to register the transfer of such
SuperGen Shares, unless the conditions specified in each of the foregoing
legends are satisfied. The first of the foregoing legends shall be removed from
any security legended pursuant to this Section 5.6.2, and SuperGen shall issue a
certificate without such legend to the holder of such SuperGen Shares, if such
SuperGen Shares are registered

                                      -24-
<PAGE>

under the Securities Act and a prospectus meeting the requirements of Section 10
of the Securities Act is available or if such holder satisfies the requirements
of Rule 144(k), or the holder provides SuperGen with an opinion of counsel,
reasonably satisfactory to SuperGen, to the effect that a public sale, transfer
or assignment of such SuperGen Shares may be made without registration. The
second of the foregoing legends shall be removed from any SuperGen Shares
legended in accordance with this Section 5.6.2, and SuperGen shall issue a
certificate without such legend to the holder of such SuperGen Share at such
time as such share is transferred in accordance with Section 5.5. The stop
transfer instructions with respect to any legended share shall be removed if
both of the foregoing legends are removed in accordance with this Section 5.6.2.

         5.7 FURTHER ASSURANCES. At any time or from time to time after the
Closing, each Subsequent Closing and the Initial Warrant Closing, each party
shall execute and deliver to the other party or parties such other documents and
instruments, provide such materials and information and take such other actions
as either party may reasonably request more effectively to carry out the
provisions of this Agreement and the other Transaction Documents.

         5.8 USE OF FUNDS. AVI shall use the proceeds from the sale of the AVI
Shares to SuperGen and the milestone payments contemplated by Section 5.1 of the
U.S. Agreement for proper corporate purposes, including allocating in a
responsible manner a sufficient portion of such proceeds and milestone payments
calculated to cause AVI to use its reasonable efforts to fulfill its obligations
under the U.S. Agreement.

         5.9 REGISTRATION RIGHTS AGREEMENT. The parties shall enter into a
registration rights agreement dated the date hereof in substantially the form
attached hereto as EXHIBIT B with respect to the AVI Shares, Warrant Shares and
SuperGen Shares.

                                    SECTION 6

                             CONDITIONS TO CLOSINGS

         6.1 CONDITIONS TO SUPERGEN'S OBLIGATION TO ACQUIRE THE AVI SHARES AND
ISSUE SUPERGEN SHARES. The obligation of SuperGen to purchase the AVI Shares
from AVI and issue SuperGen Shares to AVI hereunder is subject to the
satisfaction, on or prior to the Closing Date or the Subsequent Closing Date, as
the case may be, of the following conditions, any of which may be waived by
SuperGen, in SuperGen's sole discretion, to the extent permitted by law:

                  6.1.1 REPRESENTATIONS AND WARRANTIES CORRECT. The
representations and warranties made by AVI in this Agreement and the other
Transaction Documents shall be true and correct when made and as of the Closing
Date.

                  6.1.2 PERFORMANCE OF OBLIGATIONS. AVI shall have performed in
all material respects all covenants, agreements and other obligations required
to be performed or observed by

                                      -25-
<PAGE>

AVI pursuant to this Agreement on or prior to the Closing Date, and AVI shall
have delivered to SuperGen a certificate to such effect, executed by the chief
executive officer and chief financial officer of AVI and dated the Closing Date.

                  6.1.3 COMPLIANCE WITH LAW. At the time of the Closing and each
Subsequent Closing, the issuance by AVI and the acquisition by SuperGen of the
AVI Shares, and the issuance by SuperGen and the acquisition by AVI of the
SuperGen Shares, hereunder shall be legally permitted by all laws and
regulations to which SuperGen and AVI are subject; all waiting periods, if any,
under the HSR Act applicable to the issuance and sale of the AVI Shares and
SuperGen Shares hereunder shall have expired or been terminated and no
preliminary or permanent injunction or other order by any court of competent
jurisdiction prohibiting or otherwise restraining such acquisition shall be in
effect.

                  6.1.4 U.S. AGREEMENT. The U.S. Agreement shall be in full
force and effect and shall not have been terminated by either party thereto nor
shall either party have given notice of such termination.

                  6.1.5    PURPOSELY LEFT BLANK.

                  6.1.6 REGISTRATION RIGHTS AGREEMENT. The parties shall have
executed the Registration Rights Agreement as set forth in Section 5.9.

         6.2 CONDITIONS TO AVI'S OBLIGATION TO ISSUE AVI SHARES AND ACQUIRE
SUPERGEN SHARES. AVI's obligation to purchase SuperGen Shares from SuperGen and
sell the AVI Shares to SuperGen hereunder is subject to the satisfaction, on or
prior to the Closing Date, of the following conditions, any of which may be
waived by AVI, in its sole discretion, to the extent permitted by law:

                  6.2.1 REPRESENTATIONS AND WARRANTIES CORRECT. The
representations and warranties made by SuperGen in this Agreement shall be true
and correct when made, and shall be true and correct on the Closing Date with
the same force and effect as if they had been made on and as of the Closing
Date, and SuperGen shall have delivered to AVI a certificate to such effect,
executed by a duly authorized officer of SuperGen and dated the Closing Date.

                  6.2.2 PERFORMANCE OF OBLIGATIONS. SuperGen shall have
performed in all material respects all covenants, agreements and other
obligations required to be performed or observed by SuperGen pursuant to this
Agreement on or prior to the Closing Date, and SuperGen shall have delivered to
AVI a certificate to such effect, executed by a duly authorized officer of
SuperGen and dated the Closing Date.

                  6.2.3 COMPLIANCE WITH LAW. At the time of Closing, the
issuance by AVI and the acquisition by SuperGen of the AVI Shares, and the
issuance by SuperGen and the acquisition by

                                      -26-
<PAGE>

AVI of the SuperGen Shares, hereunder shall be legally permitted by all laws and
regulations to which either SuperGen or AVI is subject; all waiting periods, if
any, under the HSR Act applicable to the issuance and acquisition of the AVI
Shares and SuperGen Shares hereunder shall have expired or been terminated and
no preliminary or permanent injunction or other order by any court of competent
jurisdiction prohibiting or otherwise restraining such acquisition shall be in
effect.

                  6.2.4 REGISTRATION RIGHTS AGREEMENT. The parties shall have
executed the Registration Rights Agreement as set forth in Section 5.9.

         6.3 CONDITIONS TO THE INITIAL WARRANT CLOSING. The Initial Warrant
Closing shall be subject to the conditions that, on or prior to the Warrant
Closing Date, (i) the representations and warranties made by AVI and SuperGen in
this Agreement shall be true and correct on the Warrant Exercise Date, (ii) the
issuance by AVI and the acquisition by SuperGen of the Warrant Shares hereunder
shall be legally permitted by all laws and regulations to which either SuperGen
or AVI is subject, (iii) all waiting periods, if any, under the HSR Act if
applicable to the acquisition of such Warrant Shares hereunder shall have
expired or been terminated, (iv) no preliminary or permanent injunction or other
order by any court of competent jurisdiction prohibiting or otherwise
restraining such issuance or acquisition shall be in effect, and (v) this
Agreement shall have not been terminated as a result of the termination of the
U.S. Agreement.

                                    SECTION 7

                                  MISCELLANEOUS

         7.1 ACCESS TO INFORMATION. No information or knowledge obtained in any
investigation by SuperGen or AVI shall affect or be deemed to modify any
representation or warranty contained in this Agreement or the Transaction
Documents.

         7.2 WAIVERS AND AMENDMENTS. This Agreement or any provision hereof may
be amended, waived, discharged or terminated only by a statement in writing
signed by the party against which enforcement of the amendment, waiver,
discharge or termination is sought.

         7.3 GOVERNING LAW. This Agreement shall be governed in all respects by
the internal laws of the State of Delaware, without respect to the conflicts or
the laws or rules thereof.

         7.4 SURVIVAL. The representations, warranties, covenants and agreements
made in this Agreement shall survive the closings of the transactions
contemplated hereby, notwithstanding any investigation made by any party. All
statements as to factual matters contained in any certificate delivered by or on
behalf of each party pursuant hereto or in connection with the transactions
contemplated hereby shall be deemed to be representations and warranties by such
party hereunder as of the date of such certificate or instrument.

                                      -27-
<PAGE>

         7.5 SUCCESSORS AND ASSIGNS. Except as expressly provided or
contemplated by this Agreement and the other Transaction Documents, neither this
Agreement nor any right, obligation or interest hereunder shall be assigned,
either in whole or in part, by any party hereto (other than by operation of law)
without the prior written consent of the other parties; provided, that nothing
herein shall prevent or limit the ability of SuperGen or AVI to assign any or
all of its rights under this Agreement or any of the other Transaction Documents
to an affiliate. Subject to the foregoing limitations, the provisions hereof
shall inure to the benefit of, and be binding upon and enforceable by, the
parties hereto and their respective successors and assigns.

         7.6 ENTIRE AGREEMENT. This Agreement, the U.S. Agreement and the
Transaction Documents, and the other certificates and documents delivered
pursuant hereto constitute the full and entire understanding and agreement
between the parties with regard to the subjects hereof and supersede any prior
and contemporaneous agreements, understandings, negotiations and discussions,
whether oral or written, of the parties with respect thereto.

         7.7 NOTICES. All notices and other communications required or permitted
hereunder shall be in writing and shall be delivered personally or by overnight
courier or mailed by first class mail, or Express Mail, postage prepaid, or via
facsimile, addressed (a) if to AVI, at AVI BioPharma, Inc., One SW Columbia,
Portland, OR 97258, Attn: President, Alan P. Timmins, with a copy to Alter Wynne
LLC, 222 SW Columbia, #1700, Portland, Oregon 97201, Attn: Byron Milstead, or to
such other address (including electronic mail address) as AVI shall have
furnished to SuperGen in writing or by electronic mail, or (b) if to SuperGen,
at SuperGen, Inc., Two Annabel Lane, Suite 220, San Ramon, CA 94583, Attn:
President and CEO, Dr. Joseph Rubinfeld, with a copy of any said notice to be
sent to Wilson Sonsini Goodrich & Rosati, 650 Page Mill Road, Palo Alto, CA
94304-1050, Attn: Page Mailliard, Esq., or to such other address (including
electronic mail address) as SuperGen shall have furnished to AVI in writing or
by electronic mail. Notices that are mailed by (i) first class mail shall be
deemed received three (3) business days after deposit in the mail and (ii)
Express Mail or overnight courier shall be deemed received one (1) business day
after deposit in the mail or delivery to such courier. In the event that the
notice is sent by facsimile, notice shall be deemed to have been received when
sent and confirmed as to receipt.

         7.8 SEVERABILITY. In case any provision of this Agreement shall be
invalid, illegal or unenforceable, the validity, legality and enforceability of
the remaining provisions of this Agreement shall not in any way be affected or
impaired thereby.

         7.9 EXPENSES. AVI and SuperGen shall each bear their own fees, costs
and expenses incurred on their behalf with respect to the Agreement and the
transactions contemplated hereby and any amendments or waiver thereto.

         7.10 TITLES AND SUBTITLES. The titles and subtitles used in this
Agreement are used for convenience only and are not considered in construing or
interpreting this Agreement.

                                      -28-
<PAGE>

         7.11 CALIFORNIA CORPORATE SECURITIES LAW. THE SALE OF THE SECURITIES
WHICH ARE THE SUBJECT OF THIS AGREEMENT HAS NOT BEEN QUALIFIED WITH THE
COMMISSIONER OF CORPORATIONS OF THE STATE OF CALIFORNIA AND THE ISSUANCE OF SUCH
SECURITIES OR THE PAYMENT OR RECEIPT OF ANY PART OF THE CONSIDERATION THEREFOR
PRIOR TO SUCH QUALIFICATION IS UNLAWFUL UNLESS THE SALE OF SECURITIES IS EXEMPT
FROM THE QUALIFICATION BY SECTION 25100, 25102, OR 25105 OF THE CALIFORNIA
CORPORATIONS CODE. THE RIGHTS OF ALL PARTIES TO THIS AGREEMENT ARE EXPRESSLY
CONDITIONED UPON SUCH QUALIFICATION BEING OBTAINED, UNLESS THE SALE IS SO
EXEMPT.

         7.12 COUNTERPARTS. This Agreement may be executed in any number of
counterparts, each of which shall be an original, but all of which together
shall constitute one instrument.

         7.13 DELAYS OR OMISSIONS. No delay or omission to exercise any right,
power or remedy accruing to AVI or to SuperGen shall impair any such right,
power or remedy of AVI or SuperGen, nor shall it be construed to be a waiver of
any breach or default under this Agreement and the other Transaction Documents,
or an acquiescence therein or in any similar breach or default thereafter
occurring; nor shall any delay or omission to exercise any right, power or
remedy or any waiver of any single breach or default be deemed a waiver of any
other right, power or remedy or breach or default theretofore or thereafter
occurring. All remedies, either under this Agreement and the Transaction
Documents, or by law otherwise afforded to AVI or SuperGen, shall be cumulative
and not alternative.

         7.14 DISPUTE RESOLUTION.The parties hereto agree that any disputes
which may arise during the term of this Agreement which relate to either party's
rights and/or obligations hereunder shall be resolved in accordance with the ADR
provisions contained in Exhibit 20.3 of the U.S. Agreement, except that either
party may seek judicial relief or enforcement to pursue equitable or other
remedies not addressed by the ADR provisions, including without limitation
specific performance or injunctive relief, to pursue a claim of fraudulent or
otherwise inequitable treatment under the ADR proceedings or to otherwise
enforce a judgment under the ADR proceedings.

                            [SIGNATURE PAGE FOLLOWS]

                                      -29-
<PAGE>

         IN WITNESS WHEREOF, SuperGen and AVI have caused this Agreement to be
duly executed as of the date and year first above written.

                                             AVI BIOPHARMA, INC.
                                             an Oregon corporation

                                             By:  /s/ Alan P. Timmins
                                                  -----------------------------
                                                  Name: Alan P. Timmins
                                                  Title: President

                                             SUPERGEN, INC.
                                             a Delaware corporation

                                             By:  /s/ Joseph Rubinfeld
                                                  -----------------------------
                                                  Name: Joseph Rubinfeld
                                                  Title: President & CEO

                     [Signature Page to Purchase Agreement]

                                      -30-
<PAGE>

                                     FORM OF

                             COMPLIANCE CERTIFICATE

         Pursuant to Section 6.1 of that certain Common Stock and Warrant
Purchase Agreement dated as of April 4, 2000 between AVI BioPharma Inc., an
Oregon corporation ("AVI"), and SuperGen, Inc. ("SuperGen") set forth therein
(the "Agreement"), the undersigned, Alan P. Timmins, does hereby certify on
behalf of AVI as follows:

         1.       He is the duly elected President of AVI;

         2.       AVI has fulfilled all of the conditions specified in Sections
                  5 and 6 of the Agreement; and

         3.       Except as set forth in the Agreement and the disclosure
                  schedules provided to SuperGen, the representations and
                  warranties of AVI set forth in Section 3 of the Agreement are
                  true and correct as of the date hereof.

         IN WITNESS WHEREOF, the undersigned has executed this certificate on
__________ __, 2000.

                                              _________________________________
                                              Name: Alan P. Timmins
                                              Title:   President

<PAGE>

                                     FORM OF

                             COMPLIANCE CERTIFICATE

         Pursuant to Section 6.1 of that certain Common Stock and Warrant
Purchase Agreement dated as of April 4, 2000 between AVI BioPharma Inc., an
Oregon corporation ("AVI"), and SuperGen, Inc. ("SuperGen") set forth therein
(the "Agreement"), the undersigned, Joseph Rubinfeld, does hereby certify on
behalf of SuperGen as follows:

         2.       He is the duly elected Chief Executive Officer of SuperGen;

         2.       SuperGen has fulfilled all of the conditions specified in
                  Sections 5 and 6 of the Agreement; and

         3.       Except as set forth in the Agreement and the disclosure
                  schedules provided to AVI, the representations and warranties
                  of SuperGen set forth in Section 4 of the Agreement are true
                  and correct as of the date hereof.

         IN WITNESS WHEREOF, the undersigned has executed this certificate on
__________ __, 2000.

                                             ___________________________________
                                             Name: Joseph Rubinfeld
                                             Title:   Chief Executive Officer

                                      -2-<PAGE>

                                    EXHIBIT A

                          REGISTRATION RIGHTS AGREEMENT

     This Registration Rights Agreement (the "Agreement") is made as of April 4,
2000 between SuperGen, Inc., a Delaware corporation ("SuperGen") and AVI
BioPharma, Inc., an Oregon corporation ("AVI") pursuant to the terms of a Common
Stock and Warrant Purchase Agreement between the parties dated as of April 4,
2000 (the "Purchase Agreement").

                                    SECTION 1

                                   DEFINITIONS

     1.1 DEFINITIONS. As used in this Agreement, the following terms shall have
the following respective meanings:

     "ADDITIONAL SUPERGEN SHARES" shall mean the shares of SuperGen Common Stock
AVI receives from SuperGen pursuant to Section 1.3 of the Purchase Agreement.

     "AVI COMMON STOCK" shall mean AVI's common stock, par value $0.0001 per
share.

     "AVI SHARES" shall mean the shares of AVI Common Stock that SuperGen
purchases from AVI pursuant to Section 1.2 of the Purchase Agreement.

     "CLOSING DATE" shall mean the Closing Date as defined in Section 2 of the
Purchase Agreement.

     "COMMISSION" shall mean the Securities and Exchange Commission or any other
federal agency at the time administering the Securities Act.

     "MATERIAL EVENT" shall mean the happening of any event during the period
that the registration statement described in Sections 2.1 and 3.1 hereof is
required to be effective as a result of which, in the reasonable judgment of AVI
or SuperGen, as the case may be, such registration statement or the related
prospectus contains or may contain any untrue statement of a material fact or
omits or may omit to state any material fact required to be stated therein or
necessary to make the statements therein not misleading.

     "FORM S-3" means such form under the Securities Act as in effect on the
date hereof or any registration form under the Securities Act subsequently
adopted by the SEC which similarly permits inclusion or incorporation of
substantial information by reference to other documents filed by either AVI or
SuperGen with the Commission.

     "HOLDER" shall mean, for purposes of Section 2, SuperGen or any person
holding Registrable Securities to whom SuperGen's rights under Section 2 of this
Agreement have been transferred in accordance with Section 2.9, and for purposes
of Section 3, AVI or any person holding Registrable

<PAGE>

Securities to whom AVI's rights under Section 3 of this Agreement have been
transferred in accordance with Section 3.8.

     "INITIAL HOLDERS" shall mean SuperGen or any Holders who in aggregate hold
greater than 20% of the Registrable Securities for purposes of Section 2.

     "REGISTRABLE SECURITIES" shall mean, for purposes of Section 2, AVI Shares
and Warrant Shares, and for purposes of Section 3, SuperGen Shares or Additional
SuperGen Shares, as the case may be, until such time that such securities have
been (i) sold to or through a broker or dealer or underwriter in a public
distribution or a public securities transaction, or (ii) sold or are, in the
opinion of counsel for AVI in the case of AVI Shares and Warrant Shares, and
SuperGen in the case of SuperGen Shares and Additional SuperGen Shares,
available for sale in a single transaction exempt from the registration and
prospectus delivery requirements of the Securities Act so that all transfer
restrictions and restrictive legends with respect thereto are removed upon the
consummation of such sale.

     The terms "REGISTER," "REGISTERED" and "REGISTRATION" refer to a
registration effected by preparing and filing a registration statement in
compliance with the Securities Act, and the declaration or ordering of the
effectiveness of such registration statement.

     "REGISTRATION EXPENSES" shall mean all expenses, except as otherwise stated
below, incurred by AVI or SuperGen, as the registering company, in complying
with Sections 2.1, 2.2 and 2.3 (applicable to AVI) or Sections 3.1 and 3.2
(applicable to SuperGen) hereof, including, without limitation, all
registration, qualification and filing fees, printing expenses, escrow fees,
fees and disbursements of counsel for such registering company, blue sky fees
and expenses, the expense of any special audits incident to or required by any
such registration (but excluding the compensation of regular employees of AVI or
SuperGen as the registering company which shall be paid in any event by the
registering company).

     "RESTRICTED SECURITIES" shall mean any AVI Shares, Warrant Shares, SuperGen
Shares or Additional SuperGen Shares required to bear the legend set forth in
Section 5.6 of the Purchase Agreement.

     "SECURITIES ACT" shall mean the Securities Act of 1933, as amended, or any
similar federal statute and the rules and regulations of the Commission
thereunder, all as the same shall be in effect at the time.

     "SELLING EXPENSES" shall mean all underwriting discounts, selling
commissions and stock transfer taxes applicable to the securities registered by
AVI (related to Sections 2.1, 2.2 and 2.3 ) or SuperGen (related to Sections 3.1
and 3.2, except as set forth above, all reasonable fees and disbursements of
counsel for SuperGen or AVI.

     "SUPERGEN COMMON STOCK" shall mean the common stock of SuperGen, par value
$0.001.

     "SUPERGEN SHARES" shall mean the shares of SuperGen Common Stock issued to
AVI pursuant to Section 1.2 of the Purchase Agreement.

                                      -2-
<PAGE>

     "WARRANT" shall mean the warrant AVI shall issue to SuperGen pursuant to
Section 1.4 of the Purchase Agreement.

     "WARRANT SHARES" shall mean the shares of AVI Common Stock issued or
issuable upon exercise of the Warrant.

                                   SECTION 2

                  REGISTRATION OF AVI SHARES AND WARRANT SHARES

     2.1  REGISTRATION OF AVI SHARES.

          (a) REGISTRATION. AVI shall use commercially reasonable efforts to
cause the AVI Shares which are Registrable Securities to be registered under the
Securities Act no later than 90 days after the Closing Date, so as to permit the
resale thereof, and in connection therewith shall prepare and file with the SEC
and shall use commercially reasonable efforts to cause to become effective, a
Form S-3 covering the AVI Shares; PROVIDED, HOWEVER, that the Holders, if any,
shall provide all such information and materials relating to the Holders, as
applicable, and take all such action as may be required in order to permit AVI
to comply with all the applicable requirements of the Commisson and to obtain
any desired acceleration of the effective date of such Form S-3, such provision
of information and materials to be a condition precedent to the obligations of
AVI pursuant to this Agreement and the Purchase Agreement. The offerings made
pursuant to such registrations shall not be underwritten.

          (b) POSTPONEMENT OF REGISTRATION.

              (i) REGISTRATION. Notwithstanding Section 2.1(a) above, AVI shall
be entitled to postpone the declaration of effectiveness of any Form S-3
prepared and filed pursuant to this Section 2.1 for a reasonable period of time,
but not in excess of 60 calendar days after the applicable deadline, if the
Board of Directors of AVI, acting in good faith, determines that there exists
material non-public information about AVI.

              (ii) MATERIAL EVENT. The Holders agree that, upon receipt of any
notice from AVI of the happening of a Material Event, they will forthwith
discontinue disposition of the AVI Shares which are Registrable Securities
pursuant to any Form S-3 until the receipt of copies of supplemented or amended
prospectuses prepared by AVI (which AVI will use its commercially reasonable
efforts to prepare and file promptly), and, if so directed by AVI, the Holders
will deliver to AVI all copies in their possession, other than permanent file
copies then in the Holders' possession, of the prospectus covering such AVI
Shares current at the time of receipt of such notice. In no event shall AVI
delay causing to be effective a supplement or post-effective amendment to any
Form S-3 pursuant to Section 2.1 or the related prospectus, for more than 90
consecutive days or 120 days during any 365 consecutive calendar day period.

                                      -3-
<PAGE>

     2.2  REGISTRATION OF WARRANT SHARES; REQUESTED REGISTRATION.

          (a) REQUEST FOR REGISTRATION. If, at any time after the date SuperGen
exercises its Warrant, in whole or in part, AVI shall receive from the Initial
Holders a written request that AVI effect any registration, qualification or
compliance with respect to the Warrant Shares which are Registrable Securities,
AVI will,

               (i)  promptly give written notice of the proposed registration,
qualification or compliance to any other Holders; and

               (ii) as soon as practicable, use its diligent efforts to effect
such registration, qualification or compliance (including, without limitation,
appropriate qualification under applicable blue sky or other state securities
laws and appropriate compliance with applicable regulations issued under the
Securities Act and any other governmental requirements or regulations) as may be
so requested and as would permit or facilitate the sale and distribution of all
or such portion of such Registrable Securities as are specified in such request,
together with all or such portion of Registrable Securities of other Holders, if
any, joining in such request as are specified in a written request received by
AVI within 20 days after receipt of such written notice from AVI; PROVIDED,
HOWEVER, that AVI shall not be obligated to take any action to effect any such
registration, qualification or compliance pursuant to this Section 2.2:

                    (A) During the period starting with the date 60 days prior
to AVI's estimated date of filing of, and ending on the date 3 months
immediately following the effective date of, any registration statement
pertaining to securities of AVI (other than a registration of securities in a
Rule 145 transaction or with respect to an employee benefit plan), provided that
AVI is actively employing in good faith all reasonable efforts to cause such
registration statement to become effective;

                    (B) Unless the Registrable Securities sought to be
registered by the Initial Holders and other Holders pursuant to this Section 2.2
comprise at least 100,000 Warrant Shares;

                    (C) After the Company has effected two such registration
pursuant to this Section 2.2(a), and such registration has been declared or
ordered effective and the securities offered pursuant to such registrations have
been sold; or

                    (D) If AVI shall furnish to the Holders a certificate signed
by the President of AVI stating that in the good faith judgment of the Board of
Directors it would be seriously detrimental to AVI or its shareholders for a
registration statement to be filed in the near future, then AVI's obligation to
use its best efforts to register, qualify or comply under this Section 2.2 shall
be deferred for a period not to exceed 60 days from the date of receipt of
written request from the Initiating Holders, PROVIDED, HOWEVER, that AVI shall
not exercise the right to defer registration granted pursuant to this paragraph
(D) more than one time in any twelve month period.

          Subject to the foregoing clauses (A) through (D), AVI shall file a
registration statement covering the Registrable Securities so requested to be
registered as soon as practicable after receipt of the request or requests of
the Holders, but in any event within 120 days of such request or requests.

                                      -4-
<PAGE>

          (b) UNDERWRITING. In the event that a registration pursuant to Section
2.2(a) is for a registered public offering involving an underwriting, AVI shall
so advise the Holders (as part of the notice given pursuant to Section 2.2
(a)(i). In such event, the right of the Holders to registration pursuant to
Section 2.2(a) shall be conditioned upon such Holders' participation in the
underwriting arrangements required by this Section 2.2(b), and the inclusion of
such Holders' Warrant Shares which are Registrable Securities in the
underwriting to the extent requested shall be limited to the extent provided
herein.

          AVI shall (together with all Holders proposing to distribute their
securities through such underwriting) enter into an underwriting agreement in
customary form with the managing underwriter selected for such underwriting by a
majority in interest of the Holders, but subject to AVI's reasonable approval.
Notwithstanding any other provision of this Section 2.2, if the managing
underwriter advises the Holders in writing that marketing factors require a
limitation of the number of shares to be underwritten, then AVI shall so advise
all Holders of Warrant Shares which are Registrable Securities and the number of
Registrable Securities that may be included in the registration and underwriting
shall be allocated among all Holders thereof in proportion, as nearly as
practicable, to the respective amounts of Registrable Securities held by such
Holders at the time of filing the registration statement. No Registrable
Securities excluded from the underwriting by reason of the underwriter's
marketing limitation shall be included in such registration. To facilitate the
allocation of shares in accordance with the above provisions, AVI or the
underwriters may round the number of shares allocated to any Holder to the
nearest 100 shares.

          (c) If any Holder of Registrable Securities disapproves of the terms
of the underwriting, such person may elect to withdraw therefrom by written
notice to AVI, the managing underwriter and the Initial Holders. The Registrable
Securities and/or other securities so withdrawn shall also be withdrawn from
registration, and shall not be transferred in a public distribution prior to 180
days after the effective date of the registration statement relating thereto, or
such other shorter period of time as the underwriters may require.

     2.3  AVI REGISTRATION

          (a) NOTICE OF REGISTRATION. If at any time or from time to time, but
in no event earlier than SuperGen's exercise of the Warrant, AVI shall determine
to register any of its securities, either for its own account or the account of
a security holder or holders, other than (i) a registration relating solely to
employee benefit plans, or (ii) a registration relating solely to a Commission
Rule 145 transaction, AVI will:

               (i) promptly give to all Holders of Warrant Shares which are
Registrable Securities written notice thereof; and

               (ii) include in such registration (and any related qualification
under blue sky laws or other compliance), and in any underwriting involved
therein, all the Registrable Securities specified in a written request or
requests, made within twenty (20) days after receipt of such written notice from
AVI, by all Holders.

          (b) UNDERWRITING. If the registration of which AVI gives notice is for
a registered public offering involving an underwriting, AVI shall so advise the
Holders as a part of the

                                      -5-
<PAGE>

written notice given pursuant to Section 2.3(a)(i). In such event the right of
and the Holders to registration pursuant to this Section 2.3 shall be
conditioned upon the Holders' participation in such underwriting and the
inclusion of the Registrable Securities in the underwriting shall be limited to
the extent provided herein. All Holders proposing to distribute their securities
through such underwriting shall, together with AVI, enter into an underwriting
agreement in customary form with the managing underwriter selected for such
underwriting by AVI. Notwithstanding any other provision of this Section 2.3, if
the managing underwriter determines that marketing factors require a limitation
of the number of shares to be underwritten, the managing underwriter and AVI may
reduce the securities to be included in such registration to the extent the
underwriters deem necessary (to zero if necessary). AVI shall so advise the
Holders and all holders of securities distributing their securities through such
underwriting and the number of shares of Registrable Securities that may be
included in the registration and underwriting shall be allocated among all such
holders in proportion, as nearly as practicable, to the respective amounts of
Registrable Securities held by the Holders at the time of filing the
registration statement. To facilitate the allocation of shares in accordance
with the above provisions, AVI may round the number of shares allocated to any
Holder or holder to the nearest 100 shares. If any Holder or holder disapproves
of the terms of any such underwriting, it may elect to withdraw therefrom by
written notice to AVI and the managing underwriter. Any securities excluded or
withdrawn from such underwriting shall be withdrawn from such registration, and
shall not be transferred in a public distribution prior to 180 days after the
effective date of the registration statement relating thereto, or such other
shorter period of time as the underwriters may require.

          (c) RIGHT TO TERMINATE REGISTRATION. AVI shall have the right to
terminate or withdraw any registration initiated by it under this Section 2.4
prior to the effectiveness of such registration whether or not any holder has
elected to include securities in such registration.

     2.4  REGISTRATION PROCEDURES. In the case of each registration,
qualification or compliance effected by AVI pursuant to this Section 2
(including the registration on Form S-3), AVI will keep the Holders advised in
writing as to the initiation of each registration, qualification and compliance
and as to the completion thereof. At its expense AVI will:

          (a) Prepare and file with the Commission a registration statement with
respect to such securities and use its best efforts to cause such registration
statement to become and remain continuously effective for at least one year or
until the sale of all Registrable Securities described in the Registration
Statement has been completed;

          (b) Furnish to the Holders such reasonable number of copies of the
registration statement, preliminary prospectus, final prospectus and such other
documents as the Holders or such underwriters may reasonably request in order to
effect the offering and sale of the shares to be offered and sold, but only
while AVI shall be required under the provisions hereof to cause such
registration statement to remain current;

          (c) Use its commercially reasonable efforts to register or qualify the
shares of the Registrable Securities covered by such registration under the
securities or blue sky laws of such jurisdictions as the Holders shall
reasonably request (provided that AVI shall not be required in connection
therewith or as a condition thereto to qualify to do business or to file a
general consent to service of process in any such jurisdiction where it has not
been qualified), and do any and all other

                                      -6-
<PAGE>

acts or things which may be reasonably necessary or advisable to enable the
Holders to consummate the public sale or other disposition of the Registrable
Securities in such jurisdictions;

          (d) Cause all such Registrable Securities to be listed on the Nasdaq
National Market ("NNM") on which similar securities issued by AVI are then
listed;

          (e) Notify the Holders upon the happening of any event as a result of
which the prospectus included in such registration statement, as then in effect,
includes an untrue statement of a material fact or omits to state a material
fact required to be stated therein or necessary to make the statements therein
not misleading in the light of the circumstances then existing;

          (f) So long as the registration statement remains effective, promptly
prepare, file and furnish to the Holders a reasonable number of copies of a
supplement to or an amendment of such prospectus as may be necessary so that, as
thereafter delivered to the purchasers of the Registrable Securities, such
prospectus shall not include an untrue statement of a material fact or omit to
state a material fact required to be stated therein or necessary to make the
statements therein not misleading in the light of the circumstances then
existing;

          (g) Notify the Holders promptly after it shall receive notice thereof,
of the date and time any registration statement and each post-effective
amendment thereto has become effective or a supplement to any prospectus forming
a part of such registration statement has been filed;

          (h) Notify the Holders promptly of any request by the Commission for
the amending or supplementing of such registration statement or prospectus or
for additional information; and

          (i) Advise the Holders promptly after it shall receive notice or
obtain knowledge thereof, of the issuance of any stop order by the Commission
suspending the effectiveness of any registration statement or the initiation or
threatening of any proceeding for that purpose and promptly use commercially
reasonable efforts to prevent the issuance of any stop order or to obtain its
withdrawal if such stop order should be issued.

     2.5  EXPENSES OF REGISTRATION. All Registration Expenses incurred in
connection with all registrations pursuant to this Section 2 shall be borne by
AVI. Unless otherwise stated, all Selling Expenses relating to securities
registered on behalf of any holders of securities participating in the
distribution and all other Registration Expenses shall be borne by such holders
pro rata on the basis of the number of shares so registered.

                                      -7-
<PAGE>

     2.6  INDEMNIFICATION.

          (a) AVI will indemnify each Holder, each of its officers and
directors, and each person controlling such Holder within the meaning of Section
15 of the Securities Act, with respect to which registration, qualification or
compliance has been effected pursuant to this Section 2, and each underwriter,
if any, and each person who controls any underwriter within the meaning of
Section 15 of the Securities Act, against all expenses, claims, losses, damages
or liabilities (or actions in respect thereof), including any of the foregoing
incurred in settlement of any litigation, commenced or threatened, arising out
of or based on any untrue statement (or alleged untrue statement) of a material
fact contained in any registration statement, prospectus, offering circular or
other document, or any amendment or supplement thereto, incident to any such
registration, qualification or compliance, or based on any omission (or alleged
omission) to state therein a material fact required to be stated therein or
necessary to make the statements therein, in light of the circumstances in which
they were made, not misleading, or any violation by AVI of the Securities Act,
the Exchange Act, state securities law or any rule or regulation promulgated
under such laws applicable to AVI in connection with any such registration,
qualification or compliance, and within a reasonable period AVI will reimburse
each Holder, each of its officers and directors, and each person controlling
such Holder, each such underwriter and each person who controls any such
underwriter, for any legal and any other expenses reasonably incurred in
connection with investigating, preparing or defending any such claim, loss,
damage, liability or action; provided that AVI will not be liable in any such
case to the extent that any such claim, loss, damage, liability or expense
arises out of or is based on any untrue statement or omission or alleged untrue
statement or omission, made in reliance upon and in conformity with written
information furnished to AVI by an instrument duly executed by any Holder, such
controlling person or underwriter and stated to be specifically for use therein.

          (b) Each Holder will indemnify AVI, each of its directors and
officers, each underwriter, if any, of AVI's securities covered by such a
registration statement, each person who controls AVI or such underwriter within
the meaning of Section 15 of the Securities Act, and each other Holder
participating in the distribution, each of its officers and directors and each
person controlling such other Holder within the meaning of Section 15 of the
Securities Act, against all claims, losses, damages and liabilities (or actions
in respect thereof) arising out of or based on any untrue statement (or alleged
untrue statement) of a material fact contained in any such registration
statement, prospectus, offering circular or other document, or any omission (or
alleged omission) to state therein a material fact required to be stated therein
or necessary to make the statements therein not misleading, and within a
reasonable period will reimburse AVI, such other Holders, such directors,
officers, persons, underwriters or control persons for any legal or any other
expenses reasonably incurred in connection with investigating or defending any
such claim, loss, damage, liability or action, in each case to the extent, but
only to the extent, that such untrue statement (or alleged untrue statement) or
omission (or alleged omission) is made in such registration statement,
prospectus, offering circular or other document in reliance upon and in
conformity with written information furnished to AVI by an instrument duly
executed by the Holder and stated to be specifically for use therein.
Notwithstanding the foregoing, the liability of each Holder under this
subsection (b) shall be limited in an amount equal to the gross proceeds before
expenses and commissions to each Holder received for the shares sold by such
Holder, unless such liability arises out of or is based on willful misconduct by
such Holder.

                                      -8-
<PAGE>

          (c) Each party entitled to indemnification under this Section 2.6 (the
"Indemnified Party") shall give notice to the party required to provide
indemnification (the "Indemnifying Party") promptly after such Indemnified Party
has actual knowledge of any claim as to which indemnity may be sought, and shall
permit the Indemnifying Party to assume the defense of any such claim or any
litigation resulting therefrom, provided that counsel for the Indemnifying
Party, who shall conduct the defense of such claim or litigation, shall be
approved by the Indemnified Party (whose approval shall not unreasonably be
withheld), and the Indemnified Party may participate in such defense at such
party's expense, and provided further that the failure of any Indemnified Party
to give notice as provided herein shall not relieve the Indemnifying Party of
its obligations under this Section 2.7 unless the failure to give such notice is
materially prejudicial to an Indemnifying Party's ability to defend such action
and provided further, that the Indemnifying Party shall not assume the defense
for matters as to which there is a conflict of interest or separate and
different defenses. No Indemnifying Party, in the defense of any such claim or
litigation, shall, except with the consent of each Indemnified Party, consent to
entry of any judgment or enter into any settlement which does not include as an
unconditional term thereof the giving by the claimant or plaintiff to such
Indemnified Party of a release from all liability in respect to such claim or
litigation.

     2.7  INFORMATION BY HOLDER. Each Holder shall furnish to AVI such
information regarding such Holder, the Registrable Securities held by it and the
distribution proposed by such Holder as AVI may request in writing and as shall
be required in connection with any registration, qualification or compliance
referred to in this Section 2.

     2.8  RULE 144 REPORTING. With a view to making available the benefits of
certain rules and regulations of the Commission which may at any time permit the
sale of Restricted Securities to the public without registration, AVI agrees to
use its best efforts to:

          (a) Make and keep public information available, as those terms are
understood and defined in Rule 144 under the Securities Act, at all times;

          (b) Use its best efforts to file with the Commission in a timely
manner all reports and other documents required of AVI under the Securities Act
and the Exchange Act; and

          (c) So long as a Holder owns any Restricted Securities, furnish to the
Holder forthwith upon request a written statement by AVI as to its compliance
with the reporting requirements of said Rule 144 and of the Securities Act and
the Exchange Act, a copy of the most recent annual or quarterly report of AVI,
and such other reports and documents of AVI and other information in the
possession of or reasonably obtainable by AVI as the Holder may reasonably
request in availing itself of any rule or regulation of the Commission allowing
the Holder to sell any such securities without registration.

     2.9  TRANSFER OF REGISTRATION RIGHTS. The rights to cause AVI to register
securities granted a Holder under Sections 2.1, 2.2 and 2.3 may be assigned to a
transferee or assignee reasonably acceptable to AVI which acquires at least
250,000 AVI Shares or Warrant Shares in connection with any transfer or
assignment of AVI Shares or Warrant Shares by the Holder.

     2.10  STANDOFF AGREEMENT. In connection with any public offering of AVI's
securities, each Holder agrees, upon request of AVI or the underwriters managing
any underwritten offering of

                                      -9-
<PAGE>

AVI's securities, not to sell, make any short sale of, loan, grant any option
for the purchase of, or otherwise dispose of any AVI Shares or Warrant Shares
(other than those included in the registration) without the prior written
consent of AVI or such underwriters, as the case may be, for such period of time
(not to exceed ninety (90) days) from the effective date of such registration as
may be requested by the underwriters, provided that the officers and directors
of AVI who own stock of AVI and each holder representing at least 1% ownership
of AVI's outstanding Common Stock also agrees to such restrictions.

     2.11 TERMINATION OF REGISTRATION RIGHTS. The registration rights granted
pursuant to this Section 2 shall terminate as to each Holder at such time as all
AVI Shares or Warrant Shares held by such Holder may, in the opinion of counsel
to AVI (which opinion shall be addressed and rendered to the Holder), be sold in
a single three month period pursuant to Rule 144.

                                   SECTION 3

         REGISTRATION OF SUPERGEN SHARES AND ADDITIONAL SUPERGEN SHARES

     3.1  REGISTRATION OF SUPERGEN SHARES.

          (a) REGISTRATION STATEMENT. SuperGen shall use commercially reasonable
efforts to cause the SuperGen Shares which are Registrable Securities to be
registered under the Securities Act no later than 90 days after the Closing
Date, so as to permit the resale thereof, and in connection therewith shall
prepare and file with the SEC and shall use commercially reasonable efforts to
cause to become effective, a Form S-3 covering the SuperGen Shares; PROVIDED,
HOWEVER, that the Holders, if any, shall provide all such information and
materials relating to the Holders, as applicable, and take all such action as
may be required in order to permit SuperGen to comply with all the applicable
requirements of the SEC and to obtain any desired acceleration of the effective
date of such Form S-3, such provision of information and materials to be a
condition precedent to the obligations of SuperGen pursuant to this Agreement
and the Purchase Agreement. The offerings made pursuant to such registrations
shall not be underwritten.

          (b) POSTPONEMENT OF REGISTRATION

               (i) REGISTRATION. Notwithstanding Section 3.1(a) above, SuperGen
shall be entitled to postpone the declaration of effectiveness of any Form S-3
prepared and filed pursuant to this Section 3.1 for a reasonable period of time,
but not in excess of 60 calendar days after the applicable deadline, if the
Board of Directors of SuperGen, acting in good faith, determines that there
exists material non-public information about SuperGen.

               (ii) MATERIAL EVENT. The Holders agree that, upon receipt of any
notice from SuperGen of the happening of a Material Event, they will forthwith
discontinue disposition of the SuperGen Shares which are Registrable Securities
pursuant to any Form S-3 until the receipt of copies of supplemented or amended
prospectuses prepared by SuperGen (which SuperGen will use its commercially
reasonable efforts to prepare and file promptly), and, if so directed by
SuperGen, the Holders will deliver to SuperGen all copies in their possession,
other than permanent file copies then in the Holders' possession, of the
prospectus covering such SuperGen Shares current at the time of receipt of such
notice. In no event shall SuperGen delay causing to be effective a supplement or

                                      -10-
<PAGE>

post-effective amendment to any Form S-3 pursuant to this Section 3.1 or the
related prospectus, for more than 90 consecutive days or 120 days during any 365
consecutive calendar day period.

     3.2  SUPERGEN REGISTRATION

          (a) NOTICE OF REGISTRATION. If at any time or from time to time, but
in no event earlier than the issuance of any SuperGen Additional Shares,
SuperGen shall determine to register any of its securities, either for its own
account or the account of a security holder or holders, other than (i) a
registration relating solely to employee benefit plans, or (ii) a registration
relating solely to a Commission Rule 145 transaction, SuperGen will:

              (i) promptly give to all Holders of SuperGen Additional Shares
which are Registrable Securities, if any, written notice thereof; and

              (ii) include in such registration (and any related qualification
under blue sky laws or other compliance), and in any underwriting involved
therein, all the Registrable Securities specified in a written request or
requests, made within twenty (20) days after receipt of such written notice from
SuperGen, by all Holders.

          (b) UNDERWRITING. If the registration of which SuperGen gives notice
is for a registered public offering involving an underwriting, SuperGen shall so
advise the Holders as a part of the written notice given pursuant to Section
3.2(a)(i). In such event the right of the Holders to registration pursuant to
this Section 3.2 shall be conditioned upon the Holders' participation in such
underwriting and the inclusion of the Registrable Securities in the underwriting
shall be limited to the extent provided herein. All Holders proposing to
distribute their securities through such underwriting shall, together with
SuperGen, enter into an underwriting agreement in customary form with the
managing underwriter selected for such underwriting by SuperGen. Notwithstanding
any other provision of this Section 3.2, if the managing underwriter determines
that marketing factors require a limitation of the number of shares to be
underwritten, the managing underwriter and SuperGen may reduce the securities to
be included in such registration to the extent the underwriters deem necessary
(to zero if necessary). SuperGen shall so advise all Holders and other holders
distributing their securities through such underwriting and the number of shares
of Registrable Securities that may be included in the registration and
underwriting shall be allocated among all such Holders and holders in
proportion, as nearly as practicable, to the respective amounts of Registrable
Securities held by such Holders at the time of filing the Registration
Statement. To facilitate the allocation of shares in accordance with the above
provisions, SuperGen may round the number of shares allocated to any Holder or
holder to the nearest 100 shares. If any Holder or holder disapproves of the
terms of any such underwriting, it may elect to withdraw therefrom by written
notice to SuperGen and the managing underwriter. Any securities excluded or
withdrawn from such underwriting shall be withdrawn from such registration, and
shall not be transferred in a public distribution prior to 180 days after the
effective date of the registration statement relating thereto, or such other
shorter period of time as the underwriters may require.

          (c) RIGHT TO TERMINATE REGISTRATION. SuperGen shall have the right to
terminate or withdraw any registration initiated by it under this Section 3.2
prior to the effectiveness of such registration whether or not any holder has
elected to include securities in such registration.

                                      -11-
<PAGE>

     3.3  REGISTRATION PROCEDURES. In the case of each registration,
qualification or compliance effected by SuperGen pursuant to this Section 3
(including the registration Form S-3), SuperGen will keep advised in writing
as to the initiation of each registration, qualification and compliance and
as to the completion thereof. At its expense SuperGen will:

          (a) Prepare and file with the Commission a registration statement with
respect to such securities and use its best efforts to cause such registration
statement to become and remain continuously effective for at least one year or
until the sale of all Registrable Securities described in the Registration
Statement has been completed;

          (b) Furnish to the Holders such reasonable number of copies of the
registration statement, preliminary prospectus, final prospectus and such other
documents as the Holders or such underwriters may reasonably request in order to
effect the offering and sale of the shares to be offered and sold, but only
while SuperGen shall be required under the provisions hereof to cause such
registration statement to remain current;

          (c) Use its commercially reasonable efforts to register or qualify the
shares of the Registrable Securities covered by such registration under the
securities or blue sky laws of such jurisdictions as the Holders shall
reasonably request (provided that SuperGen shall not be required in connection
therewith or as a condition thereto to qualify to do business or to file a
general consent to service of process in any such jurisdiction where it has not
been qualified), and do any and all other acts or things which may be reasonably
necessary or advisable to enable the Holders to consummate the public sale or
other disposition of the Registrable Securities in such jurisdictions;

          (d) Cause all such Registrable Securities to be listed on the NNM on
which similar securities issued by AVI are then listed;

          (e) Notify the Holders upon the happening of any event as a result of
which the prospectus included in such registration statement, as then in effect,
includes an untrue statement of a material fact or omits to state a material
fact required to be stated therein or necessary to make the statements therein
not misleading in the light of the circumstances then existing;

          (f) So long as the registration statement remains effective, promptly
prepare, file and furnish to the Holders a reasonable number of copies of a
supplement to or an amendment of such prospectus as may be necessary so that, as
thereafter delivered to the purchasers of the Registrable Securities, such
prospectus shall not include an untrue statement of a material fact or omit to
state a material fact required to be stated therein or necessary to make the
statements therein not misleading in the light of the circumstances then
existing;

          (g) Notify the Holders promptly after it shall receive notice thereof,
of the date and time any registration statement and each post-effective
amendment thereto has become effective or a supplement to any prospectus forming
a part of such registration statement has been filed;

          (h) Notify the Holders promptly of any request by the Commission for
the amending or supplementing of such registration statement or prospectus or
for additional information; and

                                      -12-
<PAGE>

          (i) Advise the Holders promptly after it shall receive notice or
obtain knowledge thereof, of the issuance of any stop order by the Commisson
suspending the effectiveness of any registration statement or the initiation or
threatening of any proceeding for that purpose and promptly use commercially
reasonable efforts to prevent the issuance of any stop order or to obtain its
withdrawal if such stop order should be issued.

     3.4  EXPENSES OF REGISTRATION. All Registration Expenses incurred in
connection with all registrations pursuant to this Section 3 shall be borne by
SuperGen. Unless otherwise stated, all Selling Expenses relating to securities
registered on behalf of any holders of securities participating in the
distribution and all other Registration Expenses shall be borne by such holders
pro rata on the basis of the number of shares so registered.

     3.5  INDEMNIFICATION.

          (a) SuperGen will indemnify each Holder, each of its officers and
directors, and each person controlling such Holder within the meaning of Section
15 of the Securities Act, with respect to which registration, qualification or
compliance has been effected pursuant to this Section 3, and each underwriter,
if any, and each person who controls any underwriter within the meaning of
Section 15 of the Securities Act, against all expenses, claims, losses, damages
or liabilities (or actions in respect thereof), including any of the foregoing
incurred in settlement of any litigation, commenced or threatened, arising out
of or based on any untrue statement (or alleged untrue statement) of a material
fact contained in any registration statement, prospectus, offering circular or
other document, or any amendment or supplement thereto, incident to any such
registration, qualification or compliance, or based on any omission (or alleged
omission) to state therein a material fact required to be stated therein or
necessary to make the statements therein, in light of the circumstances in which
they were made, not misleading, or any violation by SuperGen of the Securities
Act, the Exchange Act, state securities law or any rule or regulation
promulgated under such laws applicable to SuperGen in connection with any such
registration, qualification or compliance, and within a reasonable period
SuperGen will reimburse each Holder, each of its officers and directors, and
each person controlling such Holder, each such underwriter and each person who
controls any such underwriter, for any legal and any other expenses reasonably
incurred in connection with investigating, preparing or defending any such
claim, loss, damage, liability or action; provided that SuperGen will not be
liable in any such case to the extent that any such claim, loss, damage,
liability or expense arises out of or is based on any untrue statement or
omission or alleged untrue statement or omission, made in reliance upon and in
conformity with written information furnished to SuperGen by an instrument duly
executed by such Holder, such controlling person or underwriter and stated to be
specifically for use therein.

          (b) Each Holder will indemnify SuperGen, each of its directors and
officers, each underwriter, if any, of SuperGen's securities covered by such a
registration statement, each person who controls SuperGen or such underwriter
within the meaning of Section 15 of the Securities Act, and each other Holder of
securities participating in the distribution, each of its officers and directors
and each person controlling such other Holder within the meaning of Section 15
of the Securities Act, against all claims, losses, damages and liabilities (or
actions in respect thereof) arising out of or based on any untrue statement (or
alleged untrue statement) of a material fact contained in any such registration
statement, prospectus, offering circular or other document, or any omission (or
alleged

                                      -13-
<PAGE>

omission) to state therein a material fact required to be stated therein or
necessary to make the statements therein not misleading, and within a reasonable
period will reimburse SuperGen, such other Holders, such directors, officers,
persons, underwriters or control persons for any legal or any other expenses
reasonably incurred in connection with investigating or defending any such
claim, loss, damage, liability or action, in each case to the extent, but only
to the extent, that such untrue statement (or alleged untrue statement) or
omission (or alleged omission) is made in such registration statement,
prospectus, offering circular or other document in reliance upon and in
conformity with written information furnished to SuperGen by an instrument duly
executed by such Holder and stated to be specifically for use therein.
Notwithstanding the foregoing, the liability of each Holder under this
subsection (b) shall be limited in an amount equal to the gross proceeds before
expenses and commissions to each Holder received for the shares sold by such
Holder, unless such liability arises out of or is based on willful misconduct by
such Holder.

          (c) Each party entitled to indemnification under this Section 3.5 (the
"Indemnified Party") shall give notice to the party required to provide
indemnification (the "Indemnifying Party") promptly after such Indemnified Party
has actual knowledge of any claim as to which indemnity may be sought, and shall
permit the Indemnifying Party to assume the defense of any such claim or any
litigation resulting therefrom, provided that counsel for the Indemnifying
Party, who shall conduct the defense of such claim or litigation, shall be
approved by the Indemnified Party (whose approval shall not unreasonably be
withheld), and the Indemnified Party may participate in such defense at such
party's expense, and provided further that the failure of any Indemnified Party
to give notice as provided herein shall not relieve the Indemnifying Party of
its obligations under this Section 3.5 unless the failure to give such notice is
materially prejudicial to an Indemnifying Party's ability to defend such action
and provided further, that the Indemnifying Party shall not assume the defense
for matters as to which there is a conflict of interest or separate and
different defenses. No Indemnifying Party, in the defense of any such claim or
litigation, shall, except with the consent of each Indemnified Party, consent to
entry of any judgment or enter into any settlement which does not include as an
unconditional term thereof the giving by the claimant or plaintiff to such
Indemnified Party of a release from all liability in respect to such claim or
litigation.

     3.6  INFORMATION BY THE HOLDER. Each Holder shall furnish to SuperGen such
information regarding such Holder, the Registrable Securities held by it and the
distribution proposed by such Holder as SuperGen may request in writing and as
shall be required in connection with any registration, qualification or
compliance referred to in this Section 3.

     3.7  RULE 144 REPORTING. With a view to making available the benefits of
certain rules and regulations of the Commission which may at any time permit the
sale of the Restricted Securities to the public without registration, SuperGen
agrees to use its best efforts to:

          (a) Make and keep public information available, as those terms are
understood and defined in Rule 144 under the Securities Act, at all times;

          (b) Use its best efforts to file with the Commission in a timely
manner all reports and other documents required of SuperGen under the Securities
Act and the Exchange Act; and

          (c) So long as a Holder owns any SuperGen Shares or Additional
SuperGen Shares which are Restricted Securities furnish to such Holder forthwith
upon request a written

                                      -14-
<PAGE>

statement by SuperGen as to its compliance with the reporting requirements of
said Rule 144 and of the Securities Act and the Exchange Act, a copy of the most
recent annual or quarterly report of SuperGen, and such other reports and
documents of SuperGen and other information in the possession of or reasonably
obtainable by SuperGen as the Holder may reasonably request in availing itself
of any rule or regulation of the Commission allowing such Holder to sell any
such securities without registration.

     3.8  TRANSFER OF REGISTRATION RIGHTS. The rights to cause SuperGen to
register securities granted to a Holder under Sections 3.1 and 3.2 may be
assigned to a transferee or assignee reasonably acceptable to SuperGen which
acquires at least 100,000 shares of SuperGen Shares or Additional SuperGen
Shares in connection with any transfer or assignment of SuperGen Shares or
Additional SuperGen Shares by the Holder.

     3.9  STANDOFF AGREEMENT. In connection with any public offering of
SuperGen's securities, each Holder agrees, upon request of SuperGen or the
underwriters managing any underwritten offering of SuperGen's securities, not to
sell, make any short sale of, loan, grant any option for the purchase of, or
otherwise dispose of any SuperGen Shares or Additional SuperGen Shares (other
than those included in the registration) without the prior written consent of
SuperGen or such underwriters, as the case may be, for such period of time (not
to exceed ninety (90) days) from the effective date of such registration as may
be requested by the underwriters, provided that the officers and directors of
SuperGen who own stock of SuperGen and each holder representing at least 1%
ownership of SuperGen's outstanding Common Stock also agrees to such
restrictions.

     3.10  TERMINATION OF REGISTRATION RIGHTS. The registration rights granted
pursuant to Section 3 shall terminate as to each Holder at such time as all
SuperGen Shares or Additional SuperGen Shares held by such Holder may, in the
opinion of counsel to SuperGen (which opinion shall be addressed and rendered to
the Holder), be sold in a single three month period pursuant to Rule 144.

                                      -15-
<PAGE>

                                    SECTION 4

                                  MISCELLANEOUS

     4.1  GOVERNING LAW. This Agreement shall be governed in all respects by the
internal laws of the State of Delaware.

     4.2  SURVIVAL. The covenants and agreements made herein shall survive the
closing of the transactions contemplated hereby.

     4.3  SUCCESSORS AND ASSIGNS. Except as otherwise provided herein, the
provisions hereof shall inure to the benefit of, and be binding upon, the
successors, assigns, heirs, executors and administrators of the parties hereto.

     4.4  ENTIRE AGREEMENT; AMENDMENT. This Agreement, the Purchase Agreement,
the United States of America Sales, Distribution and Development Agreement and
all exhibits hereto and thereto constitute the full and entire understanding and
agreement between the parties with regard to the subjects hereof and thereof,
and no party shall be liable or bound to any other party in any manner by any
warranties, representations or covenants except as specifically set forth herein
or therein. Except as expressly provided herein, neither this Agreement nor any
term hereof may be amended, waived, discharged or terminated other than by a
written instrument signed by the party against whom enforcement of any such
amendment, waiver, discharge or termination is sought.

     4.5  NOTICES, ETC. All notices and other communications required or
permitted hereunder shall be in writing and shall be mailed by registered or
certified mail, postage prepaid, or otherwise delivered by hand or by messenger,
addressed (a) if to AVI, at AVI BioPharma, Inc., One SW Columbia, Portland, OR
97258, Attn: President, Alan P. Timmins, with a copy to Alter Wynne LLC, 222 SW
Columbia, #1700, Portland, Oregon 97201, Attn: Byron Milstead, or to such other
address (including electronic mail address) as AVI shall have furnished to
SuperGen in writing or by electronic mail, or (b) if to SuperGen, at SuperGen,
Inc., Two Annabel Lane, Suite 220, San Ramon, CA 94583, Attn: President and CEO,
Dr. Joseph Rubinfeld, with a copy of any said notice to Wilson Sonsini Goodrich
& Rosati, 650 Page Mill Road, Palo Alto, CA 94304-1050, Attn: Page Mailliard,
Esq., or to such other address (including electronic mail address) as SuperGen
shall have furnished to AVI in writing or by electronic mail.

     Each such notice or other communication shall for all purposes of this
Agreement be treated as effective or having been given when delivered if
delivered personally, or, if sent by mail, at the earlier of its receipt or 72
hours after the same has been deposited in a regularly maintained receptacle for
the deposit of the United States mail, addressed and mailed as aforesaid.

     4.6  DELAYS OR OMISSIONS. Except as expressly provided herein, no delay or
omission to exercise any right, power or remedy accruing to any party to this
Agreement upon any breach or default of any other party under this Agreement,
shall impair any such right, power or remedy of such nondefaulting party nor
shall it be construed to be a waiver of any such breach or default, or an
acquiescence therein, or of or in any similar breach or default thereafter
occurring; nor shall any waiver of any single breach or default be deemed a
waiver of any other breach or default theretofore or thereafter occurring. Any
waiver, permit, consent or approval of any kind or character on the part

                                      -16-
<PAGE>

of any party of any breach or default under this Agreement, or any waiver on the
part of any holder of any provisions or conditions of this Agreement, must be in
writing and shall be effective only to the extent specifically set forth in such
writing. All remedies, either under this Agreement or by law or otherwise
afforded to any party to this Agreement, shall be cumulative and not
alternative.

     4.7  COUNTERPARTS. This Agreement may be executed in any number of
counterparts, each of which shall be enforceable against the parties actually
executing such counterparts, and all of which together shall constitute one
instrument.

     4.8  SEVERABILITY. In the event that any provision of this Agreement
becomes or is declared by a court of competent jurisdiction to be illegal,
unenforceable or void, this Agreement shall continue in full force and effect
without said provision; provided that no such severability shall be effective
if it materially changes the economic benefit of this Agreement to any party.

     4.9  TITLES AND SUBTITLES. The titles and subtitles used in this Agreement
are used for convenience only and are not considered in construing or
interpreting this Agreement.

                          [SIGNATURE PAGE(S) FOLLOW(S)]

                                      -17-
<PAGE>

     The foregoing Agreement is hereby executed as of the date first above
written.

                                       SUPERGEN, INC.
                                       a Delaware Corporation

                                       By: /s/ Joseph Rubinfeld
                                          --------------------------------------
                                          Joseph Rubinfeld
                                          Chief Executive Officer and President

                                       AVI BIOPHARMA, INC.
                                       an Oregon Corporation

                                       By: /s/ Alan P. Timmins
                                          --------------------------------------
                                          Alan P. Timmins
                                          President & Chief Operating Officer

                [SIGNATURE PAGE TO REGISTRATION RIGHTS AGREEMENT]

                                      -18-

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