Document:

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                                                                 EXHIBIT 10.4(b)

                              [AspenBio Letterhead]

                                 March __, 2002

Gregory Pusey
President
Cambridge Holdings, Ltd.
106 S. University Blvd. Unit 14
Denver, CO  80209

Re:     Consulting Agreement by and between AspenBio, Inc. (the "Company") and
        Cambridge Holdings, Ltd. dated December 28, 2001 (the "Consulting
        Agreement")

Dear Greg:

        Section 1 of the Consulting Agreement provides that the Consulting
Agreement may be terminated by the mutual agreement of the parties. Because the
Company considers all of the terms of the Consulting Agreement to have been
fulfilled to its satisfaction, the Company proposes that the Consulting
Agreement hereby terminate effective as of the date indicated below. In
addition, the Company proposes that the risk of forfeiture provided for in
Section 3 of the Consulting Agreement shall be lifted as of the same date.

        Please indicate your acceptance of the proposals in this letter by
signing in space provided below.

                                            Very truly yours,

                                            ASPENBIO, INC.

                                            Roger Hurst
                                            President

AGREED AND ACCEPTED EFFECTIVE THIS __ DAY OF MARCH, 2002:

-------------------------
Gregory Pusey
President
Cambridge Holdings, Ltd.<PAGE>

                                                                    EXHIBIT 10.5

                             SHAREHOLDERS AGREEMENT

THIS SHAREHOLDERS AGREEMENT (the "Agreement") is entered into this 28th day of
December, 2001 by and among AspenBio, Inc., a Colorado corporation (the
"Company"), Roger Hurst, an individual ("Hurst") and Cambridge Holdings, Ltd., a
Colorado corporation (the "Purchaser").

                                    RECITALS

WHEREAS, the Purchaser has agreed to purchase securities of the Company pursuant
to that certain "Securities Purchase Agreement" of even date herewith (the
"Purchase Agreement"); and

WHEREAS, the obligations in the Purchase Agreement are conditioned upon the
execution and delivery of this Agreement; and

WHEREAS, Hurst is president, director and controlling shareholder of the
Company; and

WHEREAS, the Company, the Purchaser and Hurst agree that their mutual interests
can best be served by providing for certain rights and obligations with respect
to the Company and the Company's securities as hereinafter provided.

                                    AGREEMENT

NOW, THEREFORE, in consideration of the foregoing recitals and the mutual
promises and covenants hereinafter set forth and for other good and valuable
consideration, the receipt and sufficiency of which are hereby acknowledged, the
parties hereto agree as follows:

1.      Board of Directors of the Company. During the period from the date
hereof to June 30, 2003, so long as the Purchaser owns a minimum of 250,000
shares of the Company's Common Stock, Hurst shall vote all shares of the
Company's voting stock owned or held of record by him at any meeting of
shareholders or in any written consent in lieu of any meeting to elect to the
Board of Directors of the Company one person designated by the Purchaser. The
designee of the Purchaser is Gregory Pusey.

The Company and Hurst agree to use their respective best efforts to call, or
cause the appropriate officers and directors of the Company to call, a special
meeting of shareholders of the Company and to vote all of the shares of Common
Stock owned or held of record by Hurst for, or take all actions by written
consent in lieu of any such meeting necessary to cause, the removal (with or
without cause) of any designee of the Purchaser if the Purchaser requests such
director's removal in writing for any reason, and to cause the election of the
person newly designated by the Purchaser. Similarly, should a designee of the
Purchaser resign or a vacancy otherwise occur, Hurst shall vote his shares of
Common Stock in favor of the candidate designated by the Purchaser to serve on
the Company's Board. Hurst shall take all action otherwise reasonably necessary
for the election to the Board of the designee of the Purchaser. Provided,
however, that

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Hurst shall have the right to approve such designee, which approval shall not be
unreasonably withheld.

2.      Tag-Along Rights.

                (a)     During the period from the date hereof to January 20,
2005, if Hurst proposes to sell any shares of the Common Stock of the Company
owned by Hurst as of the date of this Agreement representing (i) 35% or more of
the outstanding shares of the Company (on a cumulative basis) or (ii) more than
50% of the Common Stock of the Company owned by Hurst if Hurst owns less than
35% but more than 15% of the outstanding shares of the Common Stock of the
Company ((i) and (ii) each to be considered a "Qualifying Sale"), to any person
(the "Proposed Purchaser") in a sale (other than a sale pursuant to a public
offering registered under the Securities Act of 1933 as amended), then Hurst
shall afford the Purchaser the opportunity to participate in such sale in
accordance with this Section 2.

                (b)     The Purchaser shall have the right to sell at the same
price and upon identical terms and conditions as the proposed sale by Hurst, any
part or all of the shares of Common Stock owned by the Purchaser, but no more
than the number of shares of Common Stock proposed to be sold by Hurst. At the
time any sale to a Proposed Purchaser is proposed, Hurst shall give written
notice (the "Tag-Along Notice") to the Purchaser of its right to sell shares
pursuant to this Section 2, which Tag-Along Notice shall set forth the name and
address of the Proposed Purchaser, the number of shares of Common Stock proposed
to be sold, the proposed offering price, the proposed date of sale and any other
terms and conditions of the proposed sale. The Tag-Along Notice shall also
contain a copy of any written offer to Hurst by the Proposed Purchaser to
purchase Hurst's shares. The Tag-Along Notice shall also be given to the Company
at the same time as it is given to the Purchaser.

                (c)     In the event that Hurst sells and proposes to sell
shares of the Common Stock of the Company to one person or entity through more
than one sale and the total number of shares to be sold would be considered a
Qualifying Sale, then Purchaser's rights as set forth in Section 2(b) shall
become effective at the time of the proposed sale that will cause the total
shares sold by Hurst to represent (i) 35% or more of the outstanding shares of
the Company or (ii) more than 50% of the Common Stock owned by the Hurst if
Hurst owns less than 35% but more than 15% of the outstanding shares of the
Company. Purchaser shall be entitled to sell any part or all of the shares of
Common Stock owned by the Purchaser up to the cumulative total number of shares
sold and proposed to be sold by Hurst.

                (d)     In the event that the Purchaser wishes to participate,
it shall provide written notice (the "Tag-Along Acceptance Notice") to Hurst no
more than five (5) days after the Tag-Along Notice. The Tag-Along Acceptance
Notice shall set forth the number of shares of Common Stock the Purchaser elects
to sell (subject to the limitations set forth in Section 2(b)). The Notice given
by the Purchaser shall constitute its binding agreement to sell such shares on
the terms and conditions and for the same consideration per share applicable to
the sale by Hurst. If the Tag-Along Acceptance Notice is not received by Hurst
prior to the expiration of the 5-day period, then Hurst shall have the right to
sell the number of shares specified in the Tag-Along Notice to the Proposed
Purchaser without any participation by the Purchaser, but only on terms and
conditions with respect to the consideration (and other material terms and
conditions which a

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reasonable investor would consider significant to the decision to include shares
in the sale) paid by the Proposed Purchaser to Hurst which are no more favorable
in any material respect than as stated in the Tag-Along Notice to the Purchaser
and only if such sale occurs within 60 days of the date specified for sale in
the Tag-Along Notice.

3.      Termination. Except as otherwise provided herein, this Agreement shall
terminate upon the earlier to occur of (i) the mutual agreement of the Purchaser
and Hurst; (ii) the Purchaser ceasing to own more than 250,000 shares of the
Company's Common Stock; or (iii) June 30, 2003.

4.      General Provisions.

                        (a) Recapitalization, Exchanges, etc.  In the event that
any Common Stock or other securities are issued in respect of, in exchange for,
or in substitution of, any shares of Common Stock, by reason of any
reorganization, recapitalization, reclassification, merger, stock dividend,
distribution to shareholders or any other change in the capital structure of the
Company, the term Common Stock as used herein shall be deemed to include all
shares of such Common Stock or other securities, as appropriate, so as to fairly
and equitably preserve, as far as practicable, the original rights and
obligations of the Purchaser.

                        (b) Successors and Assigns. This Agreement shall be
binding upon and shall inure to the benefit of the parties hereto, and their
respective successors and permitted assigns; provided that neither this
Agreement nor any rights or obligations hereunder may be transferred or assigned
by the Company (except by operation of law in any merger), by Hurst or by the
Purchaser, except by operation of law in any merger and except that the
Purchaser may transfer and assign its rights and obligations hereunder to a
permitted transferee (as set forth on Schedule 4(b) or otherwise agreed to in
writing by Hurst) who executes and delivers to each other party hereto an
instrument or instruments reasonably satisfactory to such parties confirming
that the permitted transferee agrees to be bound by and subject to the terms of
this Agreement in the same manner as such permitted transferee's transferor.

                        (d) Notices. All notices, demands, consents or approvals
required or permitted to be given in this Agreement or given with respect to
this Agreement shall be in writing and shall be personally served or mailed,
registered or certified, return receipt requested, postage prepaid (or by a
substantially similar method), or delivered by a reputable courier service with
charges prepaid, or transmitted by hand-delivery or facsimile, addressed to the
Company or the Shareholders at their addresses set forth on the signature page
of this Agreement or such other address as such parties shall have specified
most recently by written notice. Notice shall be deemed given or delivered on
the date of service or transmission if personally served or transmitted by
facsimile. Notice otherwise sent as provided herein shall be deemed given or
delivered on the third business day following the date mailed or on the next
business day following delivery of such notice to a reputable courier service.

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                        (e) Inspection. So long as this Agreement shall be in
effect, this Agreement and any amendments hereto shall be made available for
inspection at the principal office of the Company by the Purchaser.

                        (f) Governing Law. This Agreement shall be governed by
and construed in accordance with the laws of the State of Colorado.

                (g) Specific Performance. The Purchaser, in addition to being
entitled to exercise all rights provided herein, including recovery of damages,
will be entitled to specific performance of its rights under this Agreement.

                (h) Entire Agreement. This Agreement and the Purchase Agreement
constitute the entire agreement and understanding among the parties hereto with
respect to the subject matter hereof and thereof and supersede any and all prior
agreements and understandings, written or oral, relating to the subject matter
hereof and thereof.

                (i) Waivers; Amendments.

                (i) No failure or delay by any party in exercise of any right,
        power or privilege hereunder shall operate as a waiver thereof, nor
        shall any single or partial exercise thereof preclude any other or
        further exercise thereof or the exercise of any other right, power or
        privilege. The rights and remedies herein provided shall be cumulative
        and nonexclusive of any rights or remedies provided by law.

                (ii) Any provision of this Agreement may be waived if, but only
        if, such waiver is in writing and is signed by the party against whom
        the enforcement of such waiver is sought.

                (iii) This Agreement may not be amended, modified, or
        supplemented other than by a written instrument executed by both
        parties.

                        (j) Time. Time is of the essence in performance of this
Agreement.

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                (k) Severability. Whenever possible, each provision of this
Agreement shall be interpreted in such a manner as to be effective and valid
under applicable law, and if any provision of this Agreement shall be or become
prohibited or invalid in whole or in part for any reason whatsoever, that
provision shall be ineffective only to the extent of such prohibition or
invalidity without invalidating the remaining portion of that provision or the
remaining provisions of this Agreement.

                (l) Counterparts. This Agreement may be executed in
counterparts, each of which shall constitute an original and which together
shall constitute one and the same agreement.

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

    CAMBRIDGE HOLDINGS, LTD.                  ASPENBIO, INC.

    By:                                       By:
        ------------------------------            ------------------------------

          Gregory Pusey, President                    Roger Hurst, President

    106 S. University Blvd., Unit 14              8100 Southpark Way, Bldg. B-1

    Denver, Colorado 80209                        Littleton, Colorado  80120

    Facsimile:  (303) 722 4011                    Facsimile:    (303) 798-8332

                                                  ------------------------------
                                                  Roger Hurst, Individually

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                                                  ------------------------------

                                                  ------------------------------
                                                    Facsimile:    (303) 798-8332

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                                  SCHEDULE 4(b)

                              PERMITTED TRANSFEREES

Greg Pusey
Vermut-Weinberger Living Trust UDT 3/22/93
Jeff McGonegal
John Altshuler
Scott Menefee
Robert Bearman
Cambridge Holdings, Ltd.

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