Document:

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                                                                    Exhibit 10.2

                             AMENDED AND RESTATED
                             EMPLOYMENT AGREEMENT
                                      OF
                         RALPH E. CHRISTOFFERSEN, PhD.

This amended and restated employment agreement is entered into effective July 1,
2001 by and between Ralph E. Christoffersen, PhD. ("Christoffersen") and
Ribozyme Pharmaceuticals, Inc., a Delaware corporation ("the Company"). This
agreement amends and restates all prior and existing employment agreements
between the parties.

Whereas Christoffersen has resigned as President and Chief Executive Officer of
the Company; and

Whereas the Company wishes to continue the employment of Christoffersen, and
Christoffersen is willing to continue in the employment of the Company, on the
terms and conditions set forth in this Agreement;

Now therefore the parties agree as follows:

1.   Duties of Christoffersen. Christoffersen shall assume the position of
     ------------------------
Chairman of the Board of the Company and a member of the Board's Executive
Committee upon his election to such positions by the Company's Board of
Directors and shall perform services for the Company customary for such position
as well as other duties assigned to him by the Company's Board of Directors or
as requested by the Company's President and CEO. Christoffersen shall perform
such services as a regular employee of the Company until January 1, 2002, and
thereafter as a consultant to the Company on a part time as needed basis.
Christoffersen shall not have the powers or responsibilities of an executive
officer of the Company.

2.   Compensation. In consideration for the services to be performed by
     ------------
Christoffersen through 2001, Christoffersen shall be paid a salary effective as
of the Effective Date of $13,541.67 per month payable in accordance with the
Company's customary payroll practices. In addition, Christoffersen shall be
entitled to a bonus for the year ended December 31, 2001, in an amount up to
$97,500 depending upon the achievement of certain performance goals and in
particular the successful transition of management of the Company to
Christoffersen's successor as President and CEO. From and after January 31, 2001
Christoffersen shall be compensated for any consulting engagement he undertakes
for the Company at a rate to be negotiated, but not less than $1,500 per day
plus expenses.

3.   Benefits. During the term of his employment with the Company,
     --------
Christoffersen will be entitled to participate in all health, insurance, stock,
pension and profit sharing plans made available to RPI executives including the
following:

(a)  Health and major medical insurance covering Christoffersen, his spouse and
dependents (as defined under the policies of such insurance) under the plan
maintained by the Company for
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its senior management employees with coverage for Christoffersen's spouse and
dependents paid in accordance with the Company's policies;

(b)  Long-term disability insurance coverage under the plan maintained by the
Company for its senior management employees; and

(c)  Short-term disability coverage under the plan maintained by the Company for
its senior management employees.

4.   Expenses. The Company shall promptly reimburse Christoffersen for all
     --------
ordinary, customary and necessary expenses incurred by him in the performance of
his duties, provided such expenses are incurred and accounted for in accordance
with policies and procedures established by the Company.

5.   Support Services. As long as Christoffersen is employed as an employee or
     ----------------
consultant to the Company, the Company shall provide him with appropriate office
space and secretarial support.

6.   Vacation. Each year of his employment with the Company, Christoffersen
     --------
shall be entitled to one month's vacation, or as otherwise mutually agreed, at
full salary. Christoffersen shall take vacation at such time or times as shall
be compatible with the Company's best interests and the conduct of its business.

7.   Options. Executive's stock options will continue to vest through the end of
     -------
as long as Christoffersen is employed by the Company or serving as a member of
the Board of Directors of the Company and will be exercisable for 90 days
following the later of the termination of Executive's employment or service on
the Board of Directors of the Company . In the event of a Change of Control (as
defined below) prior to the termination of Executive's employment or service on
the Board of Directors of the Company, all stock options held by Executive shall
vest and shall be immediately exercisable. As used herein, the term "Change of
Control" shall mean the occurrence with respect to the Company of any of the
following events:

(a)  An acquisition (other than directly from the Company) of any voting
securities of the Company (the "Voting Securities") by any "Person" (as the term
Person is used for purposes of Section 13 (d) or 14(d) of the Securities
Exchange Act of 1934, as amended (the "Exchange Act")) immediately after which
such Person has "Beneficial Ownership" (within the meaning of Rule 13d-3
promulgated under the Exchange Act) of fifty percent (50%) or more of the
combined voting power of the then outstanding Voting Securities; provided,
however, that in determining whether a Change of Control has occurred, Voting
Securities which are acquired in a "Non-Control Acquisition" (as hereinafter
defined) shall not constitute an acquisition which would cause a Change of
Control. A "Non-Control Acquisition" shall mean an acquisition by (i) an
employee benefit plan (or a trust forming a part thereof) maintained by (A) the
Company or (B) any subsidiary or (ii) the Company or any Subsidiary;

(b)  The individuals who, as of the date hereof, are members of the Board (the
"Incumbent Board"), cease for any reason to constitute at least two-thirds of
the Board; provided, however,

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that if the election or nomination for election by the Company's stockholders of
any new director was approved by a vote of at least two-thirds of the Incumbent
Board, such new director shall, for purposes of this Agreement, be considered as
a member of the Incumbent Board; provided, further, however, that no individual
shall be considered a member of the Incumbent Board if (1) such individual
initially assumed office as a result of either an actual or threatened "Election
Contest" (as described in Rule 14a-11 promulgated under the Exchange Act) or
other actual or threatened solicitation of proxies or consents by or on behalf
of a Person other than the Board (a "Proxy Contest") including by reason of any
agreement intended to avoid or settle any Election Contest or Proxy Contest or
(2) such individual was designated by a Person who has entered into an agreement
with the Company to effect a transaction described in clause (i) or (iii) of
this paragraph; or

(c)   Approval by stockholders of the Company of:

(i)   A merger, consolidation or reorganization involving the Company, unless,

(A)   The stockholders of the Company immediately before such merger,
consolidation or reorganization, own, directly or indirectly, immediately
following such merger, consolidation or reorganization, at least seventy-five
percent (75%) of the combined voting power of the outstanding Voting Securities
of the corporation (the "Surviving Corporation") in substantially the same
proportion as their ownership of the Voting Securities immediately before such
merger, consolidation or reorganization;

(B)   The individuals who were members of the Incumbent Board immediately prior
to the execution of the agreement providing for such merger, consolidation or
reorganization constitute at least two-thirds of the members of the board of
directors of the Surviving Corporation; and

(C)   No Person (other than the Company, any Subsidiary, any employee benefit
plan (or any trust forming a part thereof) maintained by the Company, the
Surviving Corporation or any Subsidiary, or any Person who, immediately prior to
such merger, consolidation or reorganization, had Beneficial Ownership of fifty
percent (50%) or more of the then outstanding Voting Securities) has Beneficial
Ownership of fifty percent (50%) or more of the combined voting power of the
Surviving Corporation's then outstanding Voting Securities.

(ii)  A complete liquidation or dissolution of the Company; or

(iii) An agreement for the sale or other disposition of all or substantially all
of the assets of the Company to any Person (other than a transfer to a
Subsidiary)

Notwithstanding the foregoing, a Change of Control shall not be deemed to occur
solely because any Person (the "Subject Person") acquired Beneficial Ownership
of more than the permitted amount of the outstanding Voting Securities as a
result of the acquisition of Voting Securities by the Company which, by reducing
the number of Voting Securities outstanding, increased the proportional number
of shares Beneficially Owned by the Subject Person, provided that if a Change of
Control would occur (but for the operation of this sentence) as a result of the
acquisition of Voting Securities by the Company, and after such share
acquisition by the

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Company, the Subject Person becomes the Beneficial Owner of any additional
Voting Securities Beneficially Owned by the Subject Person, then a Change of
Control shall occur.

8.   Exclusivity. Christoffersen's employment with the Company is not intended
     -----------
to be exclusive and Christoffersen is entitled to accept other part time
employment or consulting engagements and to engage in other business activities
as long as such activities to not interfere with or create a conflict of
interest with his duties under this Agreement.

9.   Confidentiality. Christoffersen acknowledges that non-public information
     ---------------
concerning the business and activities of the Company is a valuable, special and
unique asset and that he will obtain access thereto as a result of his
employment by the Company. In recognition of the foregoing, during the
continuance of his employment and thereafter for a period of five years,
Christoffersen agrees that he will not, directly or indirectly, reveal or
disclose to any person, firm, association, corporation or partnership
whatsoever, or use for his own benefit or the benefit of any other person, firm,
association, corporation or partnership, any non-public or confidential
knowledge or information concerning the Company, its business, finances,
research, or activities, including, without limitation, its business plans,
technology, manufacturing processes, research and development programs and
plans, formulas, formulations, discoveries, patents, patent applications,
licenses, contracts, marketing plans, systems, sources of supply of materials
used or sold by the Company, pricing information, the identities of former or
existing customers of the Company, and any other trade or business secrets and
confidential information of the the Company. For purposes of this paragraph,
confidential information shall also include any confidential information of any
third party revealed to Christoffersen during his employment by the Company. For
purposes of this paragraph confidential information shall not include
information that is publicly available or otherwise known to the party to whom
such information is disclosed from sources other than Christoffersen. Upon
termination of his employment with the Company, Christoffersen will immediately
surrender to the Company all documents, records, computer tapes and disks
containing confidential information of the Company and all other property
belonging to the Company.

10.  Non-Competition. Christoffersen agrees that he will not, during the
     ---------------
continuance of his employment, directly or indirectly, engage in any business or
activity which may or would compete with any aspect of the business of the
Company; except that nothing herein shall prevent Christoffersen from owning
stock in any corporation, if Christoffersen (together with his immediate family)
owns, directly or indirectly, less than 5% of the outstanding stock of such
corporation. Christoffersen and the Company agree that the restrictions
contained in this Paragraph 10 are reasonable as to their operative periods of
time and geographic scope and are necessary for the purpose of preserving the
Company's good will, proprietary rights and going concern value. However, each
and every restriction is independent and severable from the other. Therefore, no
such restriction shall be affected or rendered unenforceable in toto or with
respect to any period of time or area by reason of the fact that, for any
reason, any other restriction may be determined unenforceable in whole or in
part. Thus, if a final judicial determination is made by a court of competent
jurisdiction that the period of time or territory or any other restriction
contained in this Agreement is unenforceable, the provisions of this Agreement
shall not be rendered void but shall be enforced as to such maximum period of
time and territory and to such other maximum extent as such court may judicially
determine or indicate to be enforceable.

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11.  Termination. Christoffersen's employment shall be subject to termination as
     -----------
follows:

(a)  Christoffersen's employment hereunder shall terminate upon his death.

(b)  The Company may terminate Christoffersen's employment for any reason upon
30 days written notice.

(c)  The Company may terminate Christoffersen's employment for cause upon
written notice delivered to Christoffersen, which notice shall set forth the
reasons for termination. For purposes of this Agreement, the term "cause" shall
include (i) a material breach by Christoffersen of his obligations hereunder or
a material breach of his fiduciary duties to the Company; (ii) theft, dishonesty
or criminal conduct by Christoffersen; or (iii) an act by Christoffersen
involving moral turpitude. Termination shall be effective forthwith in the case
of termination pursuant to clause (ii) or (iii) and upon the expiration of ten
(10) days after the date of notice from the Company in the case of termination
pursuant to clause (i) above.

12.  Christoffersen's Rights Upon Termination of Employment. In the event of the
     ------------------------------------------------------
termination of Christoffersen's employment, without regard to the reason for
such termination, Christoffersen shall be entitled to receive the following
amounts:

(a)  Salary and bonuses payable under Paragraph 2 accrued and owing prior to the
date of tennination which has not previously been paid;

(b)  Benefits under any fringe benefit plan to the extent not paid for the then
current annual period, if any, applicable to such benefit plan (unless otherwise
provided by such plan), including accrued vacation, with the amount thereof
being prorated to reflect the number of days of such annual period during which
Christoffersen was employed by the Company;

(c)  Reimbursements under Paragraph 4 accrued and owing through the date of
termination; and

(d)  In the event Christoffersen's employment is terminated pursuant to
Paragraph 10(a) or (b) prior to January 1, 2002, such compensation and benefits
that would have been payable under this Agreement through such date in such
amounts, and paid at such times, as they would have been paid had
Christoffersen's employment continued to such date.

13.  Indemnification. The Company hereby agrees that during the term of this
     ---------------
Agreement and thereafter it shall indemnify Christoffersen for any claims,
losses or actions relating to his service to the ompany as an officer, director,
employee, consultant or agent of the Company to the fullest extent permitted
under the Company's Certificate of Incorporation and Bylaws and the applicable
laws of Delaware and in furtherance thereof shall advance to or on
Christoffersen's behalf all costs and expense of defending any such claim or
action to the fullest extent permitted under the Company's Certificate of
Incorporation and Bylaws and the applicable laws of Delaware. The foregoing
right to indemnification shall include, but not be limited to, indemnification
of Christoffersen in connection with the legal action entitled In Re Ribozyme

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Pharmaceuticals, Inc. Securities Lititagation, Civil Action 99-B-2235, pending
in the United States District Court for the District of Colorado.

14.  Assignment. This Agreement shall be binding upon and inure to the benefit
     ----------
of the Company, its successors and assigns, and shall be binding upon and inure
to the benefit of Christoffersen. This Agreement shall be assigned to and
assumed by any person, firm or corporation which shall acquire or succeed to the
Company's business by merger, consolidation or otherwise.

15.  Severability. The invalidity or unenforceability of any provision hereof
     ------------
shall in no way affect the validity or enforceability of any other provision.

16.  Notices. Any notice required or permitted to be given under this Agreement
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shall be sufficient, if in writing and if sent by certified mail, by overnight
mail or delivery service, or by facsimile transmission (i) to his residence in
the case of Christoffersen or (ii) to its principal office in the case of the
Company (attention President and Chief Executive Officer).

17.  Entire Agreement. This Agreement embodies the entire and exclusive
     ----------------
agreement of the parties. There are no promises, understandings, agreements,
obligations, terms or conditions other than those contained herein. This
Agreement shall supersede and nullify all previous agreements, representations
and communications of any type, whether verbal or written between the parties.
This Agreement cannot be changed or modified in any respect except by a writing
signed by both parties.

18.  Text. Whenever the context permits, words in the singular or plural herein
     ----
shall include both singular and plural. The references herein to the Company and
its rights and obligations shall be deemed references to and rights and
obligations of an assignee of this Agreement. The marginal headings are inserted
for convenience only and shall not form part of this Agreement.

19.  Counterparts. This Agreement may be executed in one or more counterparts,
     ------------
each of which shall be deemed to be an original but all of which together will
constitute one and the same instrument.

20.  Governing Law. This Agreement shall be governed and construed in accordance
     --------- ---
with the laws of the State of Colorado.

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<PAGE>

IN WITNESS WHEREOF, the Company and Christoffersen have executed this Agreement
on the respective dates set forth below.

RIBOZYME PHARMACEUTICALS, INC.

By:  /s/ David T. Morgenthaler
     ------------------------------------------------
     David T. Morgenthaler, Chairman of the Board

RALPH E. CHRISTOFFERSEN, Ph.D.

/s/ Ralph E. Christoffersen
-----------------------------------------------------

                                       7<PAGE>

                                                                    EXHIBIT 10.3

                                 AMENDMENT TO
                             EMPLOYMENT AGREEMENT

     THIS AMENDMENT TO EMPLOYMENT AGREEMENT ("Agreement") is effective as of
this 15th day of July, 2001 (the "Effective Date"), by and between RIBOZYME
PHARMACEUTICALS, INC., a Delaware corporation (the "Company"), and Marvin Tancer
("Executive").

     WHEREAS, Executive is currently an at-will employee of the Company pursuant
to a certain letter agreement dated May 29, 2001, between the Company and
Executive (the "Letter Agreement").

     WHEREAS, the Board of Directors of the Company (the "Board") has determined
that it is in the best interests of the Company and its stockholders to assure
that the Company will have the continued dedication of Executive,
notwithstanding the possibility, threat or occurrence of a Change of Control (as
defined herein);

     WHEREAS, in order to accomplish the objective described in the preceding
recital, the Board desires to cause the Company to enter into this Agreement as
set forth herein.

     NOW, THEREFORE, in consideration of the premises, the mutual covenants and
agreements contained in this Agreement, and other good and valuable
consideration, the receipt and sufficiency of which are hereby acknowledged, the
Company and Executive hereby agree as follows:

     1.1  Term. The term of this Agreement ("Term") shall commence on the
          ----
Effective Date and shall continue until the earlier of: (a) ninety days after
Executive's termination of employment with the Company if no Change of Control
shall have then been commenced, publicly announced or occurred; or (b) the
second anniversary of a Change of Control.

     1.2  Accelerated Vesting of Options. If:
          ------------------------------

          (a)  a Change of Control shall have occurred and the Executive's
          employment with the Company is terminated by the Executive for Good
          Reason; or

          (b)  during the period from ninety days prior to the commencement or
          public announcement of a Change of Control until two years after a
          Change of Control the Executive's employment with the Company is
          terminated by the Company other than for Cause;

then all unvested options granted to the Executive by the Company or any
successor entity prior to, simultaneously with or in connection with the Change
of Control  shall vest immediately prior to such termination of Employment.

     1.3  Good Reason.
          -----------
<PAGE>

          (a)  As used in this Agreement, the term "Good Reason" means:

               (i)   a material diminution in the nature of Executive's
               authorities, duties, responsibilities or status (including
               offices, titles, reporting requirements and supervisory
               functions), from those in effect immediately prior to the Change
               of Control; or

               (ii)  the required relocation of Executive's place of employment
               to a location in excess of thirty (30) miles from the Executive's
               place of employment at the time Executive terminates employment,
               except for required travel on Company business to an extent
               substantially equivalent to Executive's business travel
               obligations immediately prior to the Change of Control; or

               (iii) any reduction by the Company of Executive's base salary,
               or a reduction in Executive's bonus opportunities, profit sharing
               opportunities, or other incentive opportunities from those in
               effect immediately prior to the Change of Control; or

               (iv)  the occurrence of any event or circumstance described in
               clauses (i) through (vii) of the definition of "Good Reason" set
               forth in Appendix 1 of the Letter Agreement.

     (b)  If, at any time during the Term of this Agreement, whether before or
     after the occurrence of a Change of Control, Executive receives a written
     description from the Company of the nature of Executive's authorities,
     duties, responsibilities, status, salary, bonus and other employee
     benefits, or job location thereafter, and Executive accepts in writing such
     new authorities, duties, responsibilities, status, salary, bonus and other
     employee benefits, or job location ("New Office") with the Company without
     determining that the New Office causes a Good Reason as set forth in
     Section 1.3(a), then for the remaining Term, the New Office shall be the
     authorities, duties, responsibilities, status, salary, bonus and other
     employee benefits, or job location to be used by Executive in determining
     whether Good Reason occurs thereafter pursuant to Section 1.3(a).

     1.4  Change of Control.  As used herein, the term "Change of Control" shall
          -----------------
mean the occurrence with respect to the Company of any of the following events:

          (a)  An acquisition (other than directly from the Company) of any
     voting securities of the Company (the "Voting Securities") by any "Person"
     (as the term Person is used for purposes of Section 13 (d) or 14(d) of the
     Securities Exchange Act of 1934, as amended (the "Exchange Act"))
     immediately after which such Person has "Beneficial Ownership" (within the
     meaning of Rule 13d-3 promulgated under the Exchange Act) of fifty percent
     (50%) or more of the combined voting power of the then outstanding Voting
     Securities; provided, however, that in determining whether a Change of
     Control has occurred, Voting Securities which are acquired in a "Non-
     Control Acquisition" (as hereinafter defined) shall not constitute an
     acquisition which would cause a Change of Control. A "Non-Control
     Acquisition" shall mean an acquisition by (i) an employee

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<PAGE>

     benefit plan (or a trust forming a part thereof) maintained by (A) the
     Company or (B) any subsidiary or (ii) the Company or any Subsidiary;

          (b)  The individuals who, as of the date hereof, are members of the
     Board (the "Incumbent Board"), cease for any reason to constitute at least
     two-thirds of the Board; provided, however, that if the election or
     nomination for election by the Company's stockholders of any new director
     was approved by a vote of at least two-thirds of the Incumbent Board, such
     new director shall, for purposes of this Agreement, be considered as a
     member of the Incumbent Board; provided, further, however, that no
     individual shall be considered a member of the Incumbent Board if (1) such
     individual initially assumed office as a result of either an actual or
     threatened "Election Contest" (as described in Rule 14a-11 promulgated
     under the Exchange Act) or other actual or threatened solicitation of
     proxies or consents by or on behalf of a Person other than the Board (a
     "Proxy Contest") including by reason of any agreement intended to avoid or
     settle any Election Contest or Proxy Contest or (2) such individual was
     designated by a Person who has entered into an agreement with the Company
     to effect a transaction described in clause (i) or (iii) of this paragraph;
     or

          (c)  Approval by stockholders of the Company of:

               (i)   A merger, consolidation or reorganization involving the
          Company, unless,

                     (A) The stockholders of the Company immediately before such
               merger, consolidation or reorganization, own, directly or
               indirectly, immediately following such merger, consolidation or
               reorganization, at least seventy-five percent (75%) of the
               combined voting power of the outstanding Voting Securities of the
               corporation (the "Surviving Corporation") in substantially the
               same proportion as their ownership of the Voting Securities
               immediately before such merger, consolidation or reorganization;

                     (B) The individuals who were members of the Incumbent Board
               immediately prior to the execution of the agreement providing for
               such merger, consolidation or reorganization constitute at least
               two-thirds of the members of the board of directors of the
               Surviving Corporation; and

                     (C) no Person (other than the Company, any Subsidiary, any
               employee benefit plan (or any trust forming a part thereof)
               maintained by the Company, the Surviving Corporation or any
               Subsidiary, or any Person who, immediately prior to such merger,
               consolidation or reorganization, had Beneficial Ownership of
               fifty percent (50%) or more of the then outstanding Voting
               Securities) has Beneficial Ownership of fifty percent (50%) or
               more of the combined voting power of the Surviving Corporation's
               then outstanding Voting Securities.

                                       3
<PAGE>

               (ii)  A complete liquidation or dissolution of the Company; or

               (iii) An agreement for the sale or other disposition of all or
          substantially all of the assets of the Company to any Person (other
          than a transfer to a Subsidiary)

          Notwithstanding the foregoing, a Change of Control shall not be deemed
     to occur solely because any Person (the "Subject Person") acquired
     Beneficial Ownership of more than the permitted amount of the outstanding
     Voting Securities as a result of the acquisition of Voting Securities by
     the Company which, by reducing the number of Voting Securities outstanding,
     increased the proportional number of shares Beneficially Owned by the
     Subject Person, provided that if a Change of Control would occur (but for
     the operation of this sentence) as a result of the acquisition of Voting
     Securities by the Company, and after such share acquisition by the Company,
     the Subject Person becomes the Beneficial Owner of any additional Voting
     Securities Beneficially Owned by the Subject Person, then a Change of
     Control shall occur.

     1.5  Cause. The term "Cause" shall have the meaning set forth in Appendix 1
          -----
of the Letter Agreement.

     1.6  Governing Law.  This Agreement shall be governed by and construed in
          -------------
accordance with the laws of the state of Colorado.

     1.7  Assignability.  This Agreement is personal to Executive and without
          -------------
the prior written consent of the Company shall not be assignable by Executive
other than by will or the laws of descent and distribution.  This Agreement
shall inure to the benefit of and be enforceable by Executive's legal
representatives and heirs.  This Agreement shall inure to the benefit of and be
binding upon the Company and its successors and assigns.  The Company shall
require any corporation, entity, individual or other person who is the successor
(whether direct or indirect, by purchase, merger, consolidation, reorganization,
or otherwise) to all or substantially all of the business and/or assets of the
Company, to expressly assume and agree to perform, by a written agreement in
form and substance satisfactory to Executive, all of the obligations of the
Company under this Agreement, prior to or contemporaneously with a Change of
Control.  As used in this Agreement, the term "Company" shall mean the Company
as hereinbefore defined and any successor to its business and/or assets as
aforesaid which assumes and agrees to perform this Agreement by operation of
law, written agreement, or otherwise.

     1.8  Waiver.  This Agreement may not be changed or terminated without the
          ------
prior written agreement of both the Company and Executive.  The waiver of any
breach of any term or condition of this Agreement shall not be deemed to
constitute the waiver of any breach of the same or any other term or condition
of this Agreement.

     1.9  Severability.  In the event any provision of this Agreement is found
          ------------
to be unenforceable or invalid, such provision shall be severable from this
Agreement and shall not affect the enforceability or validity of any other
provision of this Agreement.  If any provision of this Agreement is capable to
two constructions, one of which would render the provision void

                                       4
<PAGE>

and the other that would render the provision valid, then the provision shall
have the construction that renders it valid.

     1.10 Additional Agreement. This Agreement is in addition to (and, except as
          --------------------
specifically set forth herein, does not supercede or modify any of the
provisions of) the Letter Agreement, which shall remain in full force and
effect. It is the intention of the parties that this Agreement provide
additional benefits to Executive to those set forth in the Letter Agreement; and
in the event of any conflict or inconsistency between any provision of this
Agreement and the Letter Agreement, such provision shall be interpreted to
confer upon Executive the most favorable treatment. For the avoidance of doubt,
certain stock options granted to Executive may automatically vest under certain
circumstances pursuant to the Letter Agreement even though no Change of Control
has been commenced, publicly announced or occurred as contemplated hereby.
Further, Executive is entitled to receive under the Letter Agreement additional
benefits relating to a Change of Control that are not contemplated by this
Agreement, and Executive shall be entitled to retain all such benefits under the
Letter Agreement.

                                       5
<PAGE>

     IN WITNESS WHEREOF, the parties have executed this Agreement as of the
Effective Date.

                              RIBOZYME PHARAMCEUTICALS, INC:

                              By: /s/ Howard W. Robin
                                 --------------------------------------
                                  Howard W. Robin
                                  President and Chief Executive Officer

                              EXECUTIVE:

                              By: /s/ Marvin Tancer
                                 --------------------------------------
                                   Marvin Tancer

                                       6

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