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                                                                    EXHIBIT 10.1







               STOCK PURCHASE AND SETTLEMENT AGREEMENT AND RELEASE

                                      AMONG

                              NEOTHERAPEUTICS, INC.

                                       AND

                           NEOGENE TECHNOLOGIES, INC.

                                       AND

                                SOCIETE GENERALE

                               SEPTEMBER 19, 2001







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                                TABLE OF CONTENTS

<Table>
<Caption>
<S>                                                                         <C>
1.  Definitions..............................................................1

2.  Purchase and Sale of Shares..............................................2

    (a)      Basic Transaction...............................................2
    (b)      Purchase Price..................................................2
    (c)      Dividends.......................................................2

3.  Settlement Payment.......................................................2

    (a)      Settlement Payment..............................................2
    (b)      Dividend Payment................................................3

4.  The Closing..............................................................3

    (a)      The Closing.....................................................3
    (b)      Deliveries at the Closing.......................................3

5.  Representations and Warranties...........................................3

    (a)      Representations and Warranties of the Seller....................3
    (b)      Representations and Warranties of the Buyer.....................4

6.  Releases.................................................................4

    (a)      Seller Release..................................................4
    (b)      Buyer and NeoGene Release.......................................5
    (c)      Representations and Warranties..................................5

7.  Enforcement of Agreement.................................................5


8.  Compromise...............................................................5


9.  Advice of Counsel........................................................6


10. Survival of Representations and Warranties...............................6


11. Miscellaneous............................................................6

    (a)      Further Assurances..............................................6
    (b)      No Third-Party Beneficiaries....................................6
    (c)      Successors and Assigns..........................................6
    (d)      Entire Agreement................................................6
    (e)      Counterparts....................................................6
    (f)      Headings........................................................6
    (g)      Notices.........................................................6

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    (h)      Governing Law...................................................8
    (i)      Amendments and Waivers..........................................8
    (j)      Severability....................................................8
    (k)      Expenses........................................................8
    (l)      Construction....................................................8
</Table>

                                      -ii-

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               STOCK PURCHASE AND SETTLEMENT AGREEMENT AND RELEASE


         This Stock Purchase and Settlement Agreement and Release (the
"AGREEMENT") is made and entered into as of September 19, 2001, by and among
NeoTherapeutics, Inc., a Delaware corporation (the "BUYER"), NeoGene
Technologies, Inc., a California corporation ("NEOGENE") and Societe Generale, a
bank organized under the laws of France (the "SELLER"). The Buyer, NeoGene and
the Seller are referred to collectively herein as the "PARTIES."

         WHEREAS, the Seller owns 30 shares of 7% Series C Preferred Stock
(collectively, the "SHARES") of the Buyer;

         WHEREAS, the Buyer desires to purchase from the Seller, and the Seller
desires sell to the Buyer, the Shares in return for cash;

         WHEREAS, the Parties desire to settle all disputed claims and
counterclaims, alleged penalties and alleged dividend overpayment between the
Parties.

         Now, therefore, in consideration of the premises and the mutual
promises herein made, and in consideration of the representations, warranties,
and covenants herein contained, the Parties agree as follows.

     1. DEFINITIONS.

         "AGREEMENT" means this agreement.

         "BUYER" has the meaning set forth in the preface above.

         "BUYER SERIES C PREFERRED CERTIFICATE" has the meaning set forth in
Section 6(a) below.

         "CLOSING" has the meaning set forth in Section 4(a) below.

         "CLOSING DATE" has the meaning set forth in Section 4(a) below.

         "CODE" means the Internal Revenue Code of 1986, as amended.

         "NEOGENE" has the meaning set forth in the preface above.

         "NEOGENE SERIES B PREFERRED CERTIFICATE" has the meaning set forth in
Section 6(a) below.

         "ORIGINAL AGREEMENT" has the meaning set forth in Section 5(iv) below.

         "PARTIES" has the meaning set forth in the preface above.

         "PERSON" means an individual, a partnership, a corporation, an
association, a joint stock company, a trust, a joint venture, an unincorporated
organization, or a governmental entity (or any department, agency, or political
subdivision thereof).

         "PURCHASE PRICE" has the meaning set forth in Section 2(b) below.

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         "REGISTRATION RIGHTS AGREEMENT" has the meaning set forth in Section
6(a) below.

         "RELEASED DOCUMENTS" has the meaning set forth in Section 6(a) below.

         "SECURITIES ACT" means the Securities Act of 1933, as amended.

         "SECURITY INTEREST" means any mortgage, pledge, lien, encumbrance,
charge, or other security interest.

         "SELLER" has the meaning set forth in the preface above.

         "SETTLEMENT PAYMENT" has the meaning set forth in Section 3 below.

         "SHARE" means any share of the Preferred Stock, par value $0.001 per
share, of the Buyer.

         "TAX" means any federal, state, local, or foreign income, gross
receipts, license, payroll, employment, excise, severance, stamp, occupation,
premium, windfall profits, environmental (including taxes under Code Section
59A), customs duties, capital stock, franchise, profits, withholding, social
security (or similar), unemployment, disability, real property, personal
property, sales, use, transfer, registration, value added, alternative or add-on
minimum, estimated, or other tax of any kind whatsoever, including any interest,
penalty, or addition thereto, whether disputed or not.

     2. PURCHASE AND SALE OF SHARES.

         (a) BASIC TRANSACTION. On and subject to the terms and conditions of
this Agreement, the Buyer agrees to purchase from the Seller, and the Sellers
agrees to sell to the Buyer, all of its Shares for the consideration specified
below inSection 2(b).

         (b) PURCHASE PRICE. The Buyer agrees to pay to the Seller at the
Closing the sum of $300,000 plus accrued dividends of $58.33 per day for each
day after August 31, 2001 until the Closing Date (the total payment referred to
collectively as, the "PURCHASE PRICE") by delivery of cash in the amount of the
Purchase Price payable by wire transfer or delivery of other immediately
available funds.

         (c) DIVIDENDS. The payment of any accrued, but unpaid dividends on the
Shares through August 31, 2001 shall be satisfied by the cash payment of
$16,177.78 sent by the Buyer to the Seller on August 31, 2001.

     3. SETTLEMENT PAYMENT.

         (a) SETTLEMENT PAYMENT. The Buyer agrees to pay to the Seller at the
Closing the sum of $55,000 (the "SETTLEMENT PAYMENT"), in full and complete
settlement and satisfaction of any and all Claims between the Seller and the
Buyer and between the Seller and NeoGene, arising from or in connection with the
Released Documents or the transactions contemplated by the Released Documents.
Payment shall be by delivery of cash in the amount of the Settlement Payment
payable by wire transfer or delivery of other immediately available funds.


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         (b) PAYMENT. In addition to the Settlement Payment referred to in
Section 3(a) above, the Seller shall retain the $70,000 payment made by the
Buyer to the Seller on June 15, 2001.

     4. THE CLOSING.

         (a) THE CLOSING. The closing of the transactions contemplated by this
Agreement (the "CLOSING") shall take place upon the date of the signing of this
Agreement by all Parties (the "CLOSING DATE").

         (b) DELIVERIES AT THE CLOSING. At the Closing, (i) the Seller will
deliver to the Buyer stock certificates representing all of its Shares, endorsed
for transfer to Buyer or accompanied by duly executed assignment documents, and
(ii) the Buyer will deliver to the Seller the Purchase Price and Settlement
Payment specified in Section 2(b) and Section 3, respectively, above.

     5. REPRESENTATIONS AND WARRANTIES.

         (a) REPRESENTATIONS AND WARRANTIES OF THE SELLER. The Seller represents
and warrants to the Buyer that the statements contained in this Section 3(a) are
correct and complete as of the date of this Agreement.

                  (i) AUTHORIZATION OF TRANSACTION. The Seller has full power
         and authority (including full corporate power and authority) to execute
         and deliver this Agreement and to perform his or its obligations
         hereunder. All action of the Seller necessary to authorize the
         execution and delivery of this Agreement and performance by the Seller
         of all of its obligations hereunder has been taken, and this Agreement
         constitutes the valid and legally binding obligation of the Seller,
         enforceable in accordance with its terms and conditions. The Seller
         need not give any notice to, make any filing with, or obtain any
         authorization, consent, or approval of any government or governmental
         agency in order to consummate the transactions contemplated by this
         Agreement.

                  (ii) NONCONTRAVENTION. Neither the execution and the delivery
         of this Agreement, nor the consummation of the transactions
         contemplated hereby, will violate any constitution, statute,
         regulation, rule, injunction, judgment, order, decree, ruling, charge,
         or other restriction of any government, governmental agency, or court
         to which the Seller is subject, or any provision of its charter.

                  (iii) BROKERS' FEES. The Seller has no liability or obligation
         to pay any fees or commissions to any broker, finder, or agent with
         respect to the transactions contemplated by this Agreement for which
         the Buyer could become liable or obligated.

                  (iv) SHARES. The Seller holds of record and owns beneficially
         its respective Shares as set forth in the preface to this Agreement,
         free and clear of any restrictions on transfer (other than any
         restrictions under the Securities Act and state securities laws),
         Taxes, Security Interests, options, warrants, purchase rights,
         contracts, commitments, equities, claims, and demands. The Seller is
         not a


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         party to any option, warrant, purchase right, or other contract or
         commitment that could require the Seller to sell, transfer, or
         otherwise dispose of any capital stock of the Buyer (other than this
         Agreement). The Seller is not a party to any voting trust, proxy, or
         other agreement or understanding with respect to the voting of any
         capital stock of the Buyer other than the Securities Purchase Agreement
         dated December 18, 2000 by and among the Buyer, NeoGene and the Seller
         (the "ORIGINAL AGREEMENT").

         (b) REPRESENTATIONS AND WARRANTIES OF THE BUYER. The Buyer represents
and warrants to the Seller that the statements contained in this Section 3(b)
are correct and complete as of the date of this Agreement.

                  (i) ORGANIZATION OF THE BUYER. The Buyer is a corporation duly
         organized, validly existing, and in good standing under the laws of the
         jurisdiction of its incorporation.

                  (ii) AUTHORIZATION OF TRANSACTION. The Buyer has full power
         and authority (including full corporate power and authority) to execute
         and deliver this Agreement and to perform its obligations hereunder.
         All corporate action of the Buyer necessary to authorize the execution
         and delivery of this Agreement and performance by the Buyer of all of
         its obligations hereunder has been taken, and this Agreement
         constitutes the valid and legally binding obligation of the Buyer,
         enforceable in accordance with its terms and conditions. The Buyer need
         not give any notice to, make any filing with, or obtain any
         authorization, consent, or approval of any government or governmental
         agency in order to consummate the transactions contemplated by this
         Agreement.

                  (iii) NONCONTRAVENTION. Neither the execution and the delivery
         of this Agreement, nor the consummation of the transactions
         contemplated hereby, will violate any constitution, statute,
         regulation, rule, injunction, judgment, order, decree, ruling, charge,
         or other restriction of any government, governmental agency, or court
         to which the Buyer is subject or any provision of its charter or
         bylaws.

                  (iv) BROKERS' FEES. The Buyer has no liability or obligation
         to pay any fees or commissions to any broker, finder, or agent with
         respect to the transactions contemplated by this Agreement for which
         the Seller could become liable or obligated.

     6. RELEASES.

         (a) SELLER RELEASE. For good and valuable consideration, the receipt
and sufficiency of which is hereby acknowledged, the Seller and its heirs,
successors and assigns do hereby remise, release, and forever discharge the
Buyer and NeoGene, together with their affiliates, employees, agents,
representatives, partners, shareholders, officers and directors, successors and
assigns (collectively, the "BUYER PARTIES") of and from all common law and
statutory claims, demands, damages, debts, losses, actions and causes of action,
suits, rights,


                                      -4-
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liabilities, contracts, duties and obligations, of any kind and nature
whatsoever, whether known or unknown, accrued or to accrue, contingent or
liquidated (collectively "CLAIMS"), that the Seller had, now has or may have
against the Buyer Parties, arising from or in connection with the Original
Agreement, the Registration Rights Agreement dated December 18, 2000 by and
between the Buyer and the Seller (the "REGISTRATION RIGHTS AGREEMENT"), the
Certificate of Determination of Rights, Preferences, Privileges and Restrictions
of Series B Preferred Stock of NeoGene (the "NEOGENE SERIES B PREFERRED
CERTIFICATE") and the Certificate of Designation of the 7% Series C Preferred
Stock of the Buyer (the "BUYER SERIES C PREFERRED CERTIFICATE") (the Original
Agreement, Registration Rights Agreement, the NeoGene Series B Preferred
Certificate and the Buyer Series C Preferred Certificate collectively referred
to as, the "RELEASED DOCUMENTS") or the transactions contemplated by the
Released Documents including, without limitation, any and all matters relating
to the ownership, transfer and trading of the common stock of the Buyer on or
before the date hereof.

         (b) BUYER AND NEOGENE RELEASE. For good and valuable consideration, the
receipt and sufficiency of which is hereby acknowledged, the Buyer and NeoGene
and their respective successors and assigns do hereby remise, release, and
forever discharge the Seller, together with its affiliates, agents,
representatives, successors and assigns (collectively, the "SELLER PARTIES") of
and from all Claims that the Buyer and NeoGene had, now has or may have against
the Seller Parties, arising from or in connection with the Released Documents or
the transactions contemplated by the Released Documents including, without
limitation, any and all matters relating to the ownership, transfer and trading
of the common stock of the Buyer on or before the date hereof.

         (c) REPRESENTATIONS AND WARRANTIES. Each party hereby represents and
warrants to the other that it is the current legal and beneficial owner of all
Claims, if any, released hereby and has not assigned, pledged or contracted to
assign or pledge any such Claim to any other person. Each party agrees to
indemnify, defend and hold harmless the other party from and against and in
respect of any claims, demands, losses, costs, expenses, obligations,
liabilities or damages asserted against the released party by the releasing
party in respect of any Claim.

     7. ENFORCEMENT OF AGREEMENT. This Agreement may be pleaded as the full and
complete defense to, and as a basis for an injunction against, any action, suit
or other proceeding which may be instituted, prosecuted or attempted with
respect to any Claim. If any party to this Agreement brings an action to enforce
its rights herein, or because of the breach of any covenant, condition or
provisions hereof, or for any other relief, the prevailing party shall be
entitled to recover its costs and expenses, including court costs and attorneys'
fees, if any, incurred in connection with such suit, including appeals
therefrom, whether or not such action is prosecuted to final judgment.

     8. COMPROMISE. The Parties hereto acknowledge and agree that this Agreement
is entered into as a compromise settlement which is not in any respect or for
any purpose to be deemed or construed as an admission or concession of any
liability whatsoever on the part of any party hereto.


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     9. ADVICE OF COUNSEL. The Parties have carefully and completely read this
Agreement, have not relied upon any representations or warranties of the other
party (except as set forth in this Agreement) in signing it, have had an
opportunity to review it with their attorneys, and are satisfied they understand
its terms.

     10. SURVIVAL OF REPRESENTATIONS AND WARRANTIES. All of the representations
and warranties of the Parties contained in this Agreement shall survive the
Closing hereunder (even if the damaged Party knew or had reason to know of any
misrepresentation or breach of warranty or covenant at the time of Closing) and
continue in full force and effect forever thereafter (subject to any applicable
statutes of limitations).

     11. MISCELLANEOUS.


         (a) FURTHER ASSURANCES. The Seller, the Buyer and NeoGene shall deliver
or cause to be delivered to the other Parties on the Closing Date and at such
other times and places as shall be reasonably agreed to, such additional
instruments as any of the other Parties may reasonably request for the purposes
of carrying out this Agreement.

         (b) NO THIRD-PARTY BENEFICIARIES. This Agreement shall not confer any
rights or remedies upon any Person other than the Parties and their respective
successors and permitted assigns.

         (c) SUCCESSORS AND ASSIGNS. This Agreement shall be binding upon and
inure to the benefit of and be enforceable by the Parties and their respective
successors and assigns. Notwithstanding the foregoing, neither this Agreement
nor any rights hereunder may be assigned by any Party without the prior written
consent of the other Parties.

         (d) ENTIRE AGREEMENT. This Agreement (including the documents referred
to herein) constitutes the entire agreement among the Parties and supersedes any
prior understandings, agreements, or representations by or among the Parties,
written or oral, to the extent they related in any way to the subject matter
hereof.

         (e) COUNTERPARTS. This Agreement may be executed in one or more
counterparts, each of which shall be deemed an original but all of which
together will constitute one and the same instrument.

         (f) HEADINGS. The section headings contained in this Agreement are
inserted for convenience only and shall not affect in any way the meaning or
interpretation of this Agreement.

         (g) NOTICES. All notices, requests, demands, claims, and other
communications hereunder will be in writing. Any notice, request, demand, claim,
or other communication hereunder shall be deemed duly given if (and then two
business days after) it is sent by registered or certified mail, return receipt
requested, postage prepaid, and addressed to the intended recipient as set forth
below:



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                           IF TO THE SELLERS: COPY TO:

                                    c/o SG Cowen Securities Corporation
                                    1221 Avenue of the Americas
                                    New York, New York 10020
                                    Fax: (212) 278-5467
                                    Attn: Guillaume Pollet

                           with a copy to:

                                    Jones, Day, Reavis & Pogue
                                    599 Lexington Avenue
                                    New York, New York 10020
                                    Attn: J. Eric Maki, Esq.
                                    Fax: (212) 755-7306

                           IF TO THE BUYER OR NEOGENE: COPY TO:

                                    NeoTherapeutics, Inc.
                                    157 Technology Drive
                                    Irvine, CA 92618
                                    Attn: Chief Financial Officer
                                    Fax: (949) 788-6706

                                    NeoGene Technologies, Inc.
                                    157 Technology Drive
                                    Irvine, CA 92618
                                    Attn: Chief Financial Officer
                                    Fax: (949) 788-6706

                                    with a copy to:

                                    Latham & Watkins
                                    650 Town Center Drive, Suite 2000
                                    Costa Mesa, CA 92626
                                    Attn: Alan W. Pettis, Esq.
                                    Fax: (714) 755-8290

Any Party may send any notice, request, demand, claim, or other communication
hereunder to the intended recipient at the address set forth above using any
other means (including personal delivery, expedited courier, messenger service,
telecopy, telex, ordinary mail, or electronic mail), but no such notice,
request, demand, claim, or other communication shall be deemed to have been duly
given unless and until it actually is received by the intended recipient. Any
Party may change the address to which notices, requests, demands, claims, and
other communications hereunder are to be delivered by giving the other Parties
notice in the manner herein set forth.


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         (h) GOVERNING LAW. The corporate laws of the State of Delaware shall
govern all issues concerning the relative rights of Buyer and its stockholders.
The corporate laws of the State of California shall govern all issues concerning
the relative rights of NeoGene and its shareholders. All other questions
concerning the construction, validity, enforcement and interpretation of this
Agreement shall be governed by and construed and enforced in accordance with the
internal laws of the State of New York, without regard to the principles of
conflicts of law thereof. NeoGene, Buyer and each Seller hereby irrevocably
submit to the exclusive jurisdiction of the state and federal courts sitting in
the City of New York, borough of Manhattan, for the adjudication of any dispute
hereunder or in connection herewith or with any transaction contemplated hereby
or discussed herein, and hereby irrevocably waives, and agrees not to assert in
any suit, action or proceeding, any claim that it is not personally subject to
the jurisdiction of any such court, or that such suit, action or proceeding is
improper. Each of NeoGene, Buyer and each Seller hereby irrevocably waives
personal service of process and consents to process being served in any such
suit, action or proceeding by receiving a copy thereof sent to NeoGene, the
Buyer and the Seller at the addresses in effect for notices to it under this
instrument and agrees that such service shall constitute good and sufficient
service of process and notice thereof. Nothing contained herein shall be deemed
to limit in any way any right to serve process in any manner permitted by law.

         (i) AMENDMENTS AND WAIVERS. No amendment of any provision of this
Agreement shall be valid unless the same shall be in writing and signed by
NeoGene, the Buyer and the Seller. No waiver by any Party of any default,
misrepresentation, or breach of warranty or covenant hereunder, whether
intentional or not, shall be deemed to extend to any prior or subsequent
default, misrepresentation, or breach of warranty or covenant hereunder or
affect in any way any rights arising by virtue of any prior or subsequent such
occurrence.

         (j) SEVERABILITY. Any term or provision of this Agreement that is
invalid or unenforceable in any situation in any jurisdiction shall not affect
the validity or enforceability of the remaining terms and provisions hereof or
the validity or enforceability of the offending term or provision in any other
situation or in any other jurisdiction.

         (k) EXPENSES. Each of the Parties will bear his or its own costs and
expenses (including legal fees and expenses) incurred in connection with this
Agreement and the transactions contemplated hereby.

         (l) CONSTRUCTION. Any reference to any federal, state, local, or
foreign statute or law shall be deemed also to refer to all rules and
regulations promulgated thereunder, unless the context requires otherwise. The
word "including" shall mean including without limitation. The Parties intend
that each representation, warranty, and covenant contained herein shall have
independent significance. If any Party has breached any representation,
warranty, or covenant contained herein in any respect, the fact that there
exists another representation, warranty, or covenant relating to the same
subject matter (regardless of the relative levels of specificity) which the
Party has not breached shall not detract from or mitigate the fact that the
Party is in breach of the first representation, warranty, or covenant.

                                      *****




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         IN WITNESS WHEREOF, the Parties hereto have executed this Agreement as
of the date first above written.

                                       NEOTHERAPEUTICS, INC.

                                       By:     /s/ Samuel Gulko
                                               --------------------------------
                                       Title:  Chief Financial Officer
                                               --------------------------------

                                       NEOGENE TECHNOLOGIES, INC.

                                       By:     /s/ Samuel Gulko
                                               --------------------------------
                                       Title:  Chief Financial Officer
                                               --------------------------------

                                       SOCIETE GENERALE

                                       By:     /s/ Guillaume Pollet
                                               --------------------------------
                                       Title:  Managing Director
                                               --------------------------------



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