Exhibit 10.6

ARCA BIOPHARMA, INC.

STOCK OPTION AGREEMENT

Optionee:                                     

Date of Grant:                             

ARCA biopharma, Inc. (f/k/a Nuvelo, Inc.) has granted to the individual (the
“Optionee”) named in the Notice of Grant of Stock Option (the “Notice”) to which
this Stock Option Agreement (the “Option Agreement”) is attached an option (the
“Option”) to purchase certain shares of Stock upon the terms and conditions set
forth in the Notice and this Option Agreement. The Option has been granted
pursuant to and shall in all respects be subject to the terms and conditions of
the Nuvelo, Inc. 2004 Equity Incentive Plan (the “Plan”), as amended to the Date
of Option Grant, the provisions of which are incorporated herein by reference.
By signing the Notice, the Optionee: (a) represents that the Optionee has read
and is familiar with the terms and conditions of the Notice, the Plan and this
Option Agreement, including the Effect of Termination of Service set forth in
Section 7 below, (b) accepts the Option subject to all of the terms and
conditions of the Notice, the Plan and this Option Agreement, (c) agrees to
accept as binding, conclusive and final all decisions or interpretations of the
Board upon any questions arising under the Notice, the Plan or this Option
Agreement, and (d) acknowledges receipt of a copy of the Notice, the Plan and
this Option Agreement.

 

  1. DEFINITIONS AND CONSTRUCTION.

1.1        Definitions.  Unless otherwise defined herein, capitalized terms
shall have the meanings assigned to such terms in the Notice or the Plan.

1.2        Construction.  Captions and titles contained herein are for
convenience only and shall not affect the meaning or interpretation of any
provision of this Option Agreement. Except when otherwise indicated by the
context, the singular shall include the plural and the plural shall include the
singular. Use of the term “or” is not intended to be exclusive, unless the
context clearly requires otherwise.

 

  2. TAX CONSEQUENCES.

2.1        Tax Status of Option.  This Option is intended to have the tax status
designated in the Notice.

    (a)        Incentive Stock Option.  If the Notice so designates, this Option
is intended to be an Incentive Stock Option within the meaning of Section 422(b)
of the Code, but the Company does not represent or warrant that this Option
qualifies as such. The Optionee should consult with the Optionee’s own tax
advisor regarding the tax effects of this Option and the requirements necessary
to obtain favorable income tax treatment under Section 422 of the Code,
including, but not limited to, holding period requirements. (NOTE TO OPTIONEE:
If the Option is exercised more than three (3) months after the date on which
you cease to be an

 

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Employee (other than by reason of your death or permanent and total disability
as defined in Section 22(e)(3) of the Code), the Option will be treated as a
Nonstatutory Stock Option and not as an Incentive Stock Option to the extent
required by Section 422 of the Code.)

    (b)        Nonstatutory Stock Option.  If the Notice so designates, this
Option is intended to be a Nonstatutory Stock Option and shall not be treated as
an Incentive Stock Option within the meaning of Section 422(b) of the Code.

2.2        ISO Fair Market Value Limitation.  If the Notice designates this
Option as an Incentive Stock Option, then to the extent that the Option
(together with all Incentive Stock Options granted to the Optionee under all
stock option plans of the Participating Company Group, including the Plan)
becomes exercisable for the first time during any calendar year for shares
having a Fair Market Value greater than One Hundred Thousand Dollars ($100,000),
the portion of such options which exceeds such amount will be treated as
Nonstatutory Stock Options. For purposes of this Section 2.2, options designated
as Incentive Stock Options are taken into account in the order in which they
were granted, and the Fair Market Value of stock is determined as of the time
the option with respect to such stock is granted. If the Code is amended to
provide for a different limitation from that set forth in this Section 2.2, such
different limitation shall be deemed incorporated herein effective as of the
date required or permitted by such amendment to the Code. If the Option is
treated as an Incentive Stock Option in part and as a Nonstatutory Stock Option
in part by reason of the limitation set forth in this Section 2.2, the Optionee
may designate which portion of such Option the Optionee is exercising. In the
absence of such designation, the Optionee shall be deemed to have exercised the
Incentive Stock Option portion of the Option first. Separate certificates
representing each such portion shall be issued upon the exercise of the Option.
(NOTE TO OPTIONEE: If the aggregate Exercise Price of the Option (that is, the
Exercise Price multiplied by the Number of Option Shares) plus the aggregate
exercise price of any other Incentive Stock Options you hold (whether granted
pursuant to the Plan or any other stock option plan of the Participating Company
Group) is greater than $100,000, you should contact the Chief Financial Officer
of the Company to ascertain whether the entire Option qualifies as an Incentive
Stock Option.)

 

  3. ADMINISTRATION.

All questions of interpretation concerning this Option Agreement shall be
determined by the Board. All determinations by the Board shall be final and
binding upon all persons having an interest in the Option. Any officer of a
Participating Company shall have the authority to act on behalf of the Company
with respect to any matter, right, obligation, or election which is the
responsibility of or which is allocated to the Company herein, provided the
officer has apparent authority with respect to such matter, right, obligation,
or election.

 

  4. EXERCISE OF THE OPTION.

4.1        Right to Exercise.  Except as otherwise provided herein, the Option
shall be exercisable on and after the Date of Option Grant (or if later, the
Optionee’s Service commencement date) and prior to the termination of the Option
(as provided in Section 6) in an amount not to exceed (a) the number of Option
Shares that have vested in accordance with the vesting provisions set forth in
the Notice and this Option Agreement, minus (b) the number of

 

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Option Shares previously acquired upon exercise of the Option. Notwithstanding
the foregoing, if Optionee is an Employee eligible for overtime compensation
under the Fair Labor Standards Act of 1938, as amended (i.e., a “Non-Exempt
Employee”), Optionee may not exercise the Option as to vested Option Shares
until the earliest of (i) the date that is six (6) months and one (1) day after
the Date of Option Grant, (ii) the date of Optionee’s death or Disability,
(iii) immediately prior to the date of a Change in Control and (iv) the date of
Optionee’s retirement.

4.2        Method of Exercise.  Exercise of the Option shall be by written
notice to the Company which must state the election to exercise the Option, the
number of whole shares of Stock for which the Option is being exercised and such
other representations and agreements as to the Optionee’s investment intent with
respect to such shares as may be required pursuant to the provisions of this
Option Agreement. The written notice must be signed by the Optionee and must be
delivered in person, by certified or registered mail, return receipt requested,
by confirmed facsimile transmission, or by such other means as the Company may
permit, to the Chief Financial Officer of the Company, or other authorized
representative of the Participating Company Group, prior to the termination of
the Option as set forth in Section 6, accompanied by full payment of the
aggregate Exercise Price for the number of shares of Stock being purchased. The
Option shall be deemed to be exercised upon receipt by the Company of such
written notice and the aggregate Exercise Price.

4.3        Payment of Exercise Price.

    (a)        Forms of Consideration Authorized.  Except as otherwise provided
below, payment of the aggregate Exercise Price for the number of shares of Stock
for which the Option is being exercised shall be made (i) in cash, by check, or
cash equivalent, (ii) by tender to the Company, or attestation to the ownership,
of whole shares of Stock owned by the Optionee having a Fair Market Value (as
determined by the Company without regard to any restrictions on transferability
applicable to such stock by reason of federal or state securities laws or
agreements with an underwriter for the Company) not less than the aggregate
Exercise Price, (iii) to the extent this Option is not an Incentive Stock
Option, by means of a Cashless Exercise, as defined in Section 4.3(b), or
(iv) by any combination of the foregoing.

    (b)        Limitations on Forms of Consideration.

      (i)        Tender of Stock.  Notwithstanding the foregoing, the Option may
not be exercised by tender to the Company, or attestation to the ownership, of
shares of Stock to the extent such tender or attestation would constitute a
violation of the provisions of any law, regulation or agreement restricting the
redemption of the Company’s stock. The Option may not be exercised by tender to
the Company, or attestation to the ownership, of shares of Stock unless such
shares either have been owned by the Optionee for more than six (6) months or
were not acquired, directly or indirectly, from the Company.

      (ii)        Cashless Exercise.  A “Cashless Exercise” means the delivery
of a properly executed notice together with irrevocable instructions to a broker
in a form acceptable to the Company providing for the assignment to the Company
of the proceeds of a sale or loan with respect to some or all of the shares of
Stock acquired upon the exercise of the Option pursuant to a program or
procedure approved by the Company (including, without

 

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limitation, through an exercise complying with the provisions of Regulation T as
promulgated from time to time by the Board of Governors of the Federal Reserve
System). The Company reserves, at any and all times, the right, in the Company’s
sole and absolute discretion, to decline to approve or terminate any such
program or procedure.

4.4        Tax Withholding.  At the time the Option is exercised, in whole or in
part, or at any time thereafter as requested by the Company, the Optionee hereby
authorizes withholding from payroll and any other amounts payable to the
Optionee, and otherwise agrees to make adequate provision for (including by
means of a Cashless Exercise to the extent permitted by the Company), any sums
required to satisfy the federal, state, local and foreign tax withholding
obligations of the Participating Company Group, if any, which arise in
connection with the Option, including, without limitation, obligations arising
upon (a) the exercise, in whole or in part, of the Option, (b) the transfer, in
whole or in part, of any shares acquired upon exercise of the Option, (c) the
operation of any law or regulation providing for the imputation of interest, or
(d) the lapsing of any restriction with respect to any shares acquired upon
exercise of the Option. The Company shall have no obligation to deliver shares
of Stock until the tax withholding obligations of the Participating Company
Group have been satisfied by the Optionee.

4.5        Certificate Registration.  Except in the event the Exercise Price is
paid by means of a Cashless Exercise, the certificate for the shares as to which
the Option is exercised shall be registered in the name of the Optionee, or, if
applicable, in the names of the heirs of the Optionee.

4.6        Restrictions on Grant of the Option and Issuance of Shares.  The
grant of the Option and the issuance of shares of Stock upon exercise of the
Option shall be subject to compliance with all applicable requirements of
federal, state or foreign law with respect to such securities. The Option may
not be exercised if the issuance of shares of Stock upon exercise would
constitute a violation of any applicable federal, state or foreign securities
laws or other law or regulations or the requirements of any stock exchange or
market system upon which the Stock may then be listed. In addition, the Option
may not be exercised unless (a) a registration statement under the Securities
Act shall at the time of exercise of the Option be in effect with respect to the
shares issuable upon exercise of the Option or (b) in the opinion of legal
counsel to the Company, the shares issuable upon exercise of the Option may be
issued in accordance with the terms of an applicable exemption from the
registration requirements of the Securities Act. THE OPTIONEE IS CAUTIONED THAT
THE OPTION MAY NOT BE EXERCISED UNLESS THE FOREGOING CONDITIONS ARE SATISFIED.
ACCORDINGLY, THE OPTIONEE MAY NOT BE ABLE TO EXERCISE THE OPTION WHEN DESIRED
EVEN THOUGH THE OPTION IS VESTED. The inability of the Company to obtain from
any regulatory body having jurisdiction the authority, if any, deemed by the
Company’s legal counsel to be necessary to the lawful issuance and sale of any
shares subject to the Option shall relieve the Company of any liability in
respect of the failure to issue or sell such shares as to which such requisite
authority shall not have been obtained. As a condition to the exercise of the
Option, the Company may require the Optionee to satisfy any qualifications that
may be necessary or appropriate, to evidence compliance with any applicable law
or regulation and to make any representation or warranty with respect thereto as
may be requested by the Company.

 

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4.7        Fractional Shares.  The Company shall not be required to issue
fractional shares upon the exercise of the Option.

 

  5. TRANSFERABILITY OF THE OPTION.

The Option may generally only be exercised during the lifetime of the Optionee
only by the Optionee or the Optionee’s guardian or legal representative and may
not be exercised, assigned or transferred in any manner except by will, by the
laws of descent and distribution, or as otherwise provided in the Plan.
Following the death of the Optionee, the Option, to the extent provided in
Section 7, may be exercised by the Optionee’s legal representative or by any
person empowered to do so under the deceased Optionee’s will or under the then
applicable laws of descent and distribution.

 

  6. TERMINATION OF THE OPTION.

The Option shall terminate and may no longer be exercised on the first to occur
of (a) the Option Expiration Date, (b) the last date for exercising the Option
following termination of the Optionee’s Service as described in Section 7, or
(c) a Change in Control to the extent provided in Section 8.

 

  7. EFFECT OF TERMINATION OF SERVICE.

7.1        Option Exercisability.

    (a)        Disability.  If the Optionee’s Service with the Participating
Company Group terminates because of the Disability of the Optionee, the Option,
to the extent unexercised and exercisable on the date on which the Optionee’s
Service terminated, may be exercised by the Optionee (or the Optionee’s guardian
or legal representative) at any time prior to the expiration of twelve
(12) months after the date on which the Optionee’s Service terminated, but in
any event no later than the Option Expiration Date.

    (b)        Death.  If the Optionee’s Service with the Participating Company
Group terminates because of the death of the Optionee, the Option, to the extent
unexercised and exercisable on the date on which the Optionee’s Service
terminated, may be exercised by the Optionee’s legal representative or other
person who acquired the right to exercise the Option by reason of the Optionee’s
death at any time prior to the expiration of twelve (12) months after the date
on which the Optionee’s Service terminated, but in any event no later than the
Option Expiration Date. The Optionee’s Service shall be deemed to have
terminated on account of death if the Optionee dies within three (3) months
after the Optionee’s termination of Service.

    (c)        Other Termination of Service.  If the Optionee’s Service with the
Participating Company Group terminates for any reason, except Disability or
death, the Option, to the extent unexercised and exercisable by the Optionee on
the date on which the Optionee’s Service terminated, may be exercised by the
Optionee at any time prior to the expiration of three (3) months (or such other
longer period of time as determined by the Board, in its discretion) after the
date on which the Optionee’s Service terminated, but in any event no later than
the Option Expiration Date. Notwithstanding the foregoing, if Optionee is a
Non-Exempt Employee

 

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whose Service terminates within seven (7) months after the Date of Option Grant,
this Option shall not expire until the earlier of (x) the later of (A) the date
that is nine (9) months after the Date of Option Grant or (B) the date that is
three (3) months after the termination of Service, or (y) the Option Expiration
Date.

7.2        Extension if Exercise Prevented by Law.  Notwithstanding the
foregoing, if the exercise of the Option within the applicable time periods set
forth in Section 7.1 is prevented by the provisions of Section 4.6, the Option
shall remain exercisable until three (3) months after the date the Optionee is
notified by the Company that the Option is exercisable, but in any event no
later than the Option Expiration Date.

7.3        Extension if Optionee Subject to Section 16(b).  Notwithstanding the
foregoing, if a sale within the applicable time periods set forth in Section 7.1
of shares acquired upon the exercise of the Option would subject the Optionee to
suit under Section 16(b) of the Exchange Act, the Option shall remain
exercisable until the earliest to occur of (a) the tenth (10th) day following
the date on which a sale of such shares by the Optionee would no longer be
subject to such suit, (b) the one hundred and ninetieth (190th) day after the
Optionee’s termination of Service, or (c) the Option Expiration Date.

7.4        Extension if Exercise Prevented by Lock-Up
Agreement.  Notwithstanding the foregoing, if the exercise of the Option within
any portion of the applicable time period set forth in Section 7.1(c) is
prevented by the provisions of lock-up agreement between the Optionee and an
underwriter of any of securities issued by the Company, the Option shall remain
exercisable until three (3) months after the expiration of the term of any such
lock-up agreement, but in any event no later than the Option Expiration Date.

 

  8. CHANGE IN CONTROL.

    (a)      In the event of a Change in Control, the Option may be subject to
acceleration of exercisability and vesting in accordance with the terms of the
Plan, and the Acquiring Corporation may either assume the Company’s rights and
obligations under the Option or substitute for the Option a substantially
equivalent option for the Acquiring Corporation’s stock. The Option shall
terminate and cease to be outstanding effective as of the date of the Change in
Control to the extent that the Option is neither assumed or substituted for by
the Acquiring Corporation in connection with the Change in Control nor exercised
as of the date of the Change in Control. Notwithstanding the foregoing, shares
acquired upon exercise of the Option prior to the Change in Control and any
consideration received pursuant to the Change in Control with respect to such
shares shall continue to be subject to all applicable provisions of this Option
Agreement except as otherwise provided herein.

    (b)      This Option and the Option Shares issuable upon exercise of this
Option shall become immediately vested and exercisable in full as of immediately
prior to the closing of a Change in Control consummated after the date this
Option is granted, subject to the Optionee’s continued Service at the time such
Change of Control is consummated.

 

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  9. ADJUSTMENTS FOR CHANGES IN CAPITAL STRUCTURE.

In the event of any stock dividend, stock split, reverse stock split,
recapitalization, combination, reclassification, or similar change in the
capital structure of the Company, appropriate adjustments shall be made in the
number, Exercise Price and class of shares of stock subject to the Option. If a
majority of the shares which are of the same class as the shares that are
subject to the Option are exchanged for, converted into, or otherwise become
(whether or not pursuant to an Ownership Change Event) shares of another
corporation (the “New Shares”), the Board may unilaterally amend the Option to
provide that the Option is exercisable for New Shares. In the event of any such
amendment, the Number of Option Shares and the Exercise Price shall be adjusted
in a fair and equitable manner, as determined by the Board, in its discretion.
Notwithstanding the foregoing, any fractional share resulting from an adjustment
pursuant to this Section 9 shall be rounded down to the nearest whole number,
and in no event may the Exercise Price be decreased to an amount less than the
par value, if any, of the stock subject to the Option. The adjustments
determined by the Board pursuant to this Section 9 shall be final, binding and
conclusive.

 

  10. RIGHTS AS A STOCKHOLDER, EMPLOYEE OR CONSULTANT.

The Optionee shall have no rights as a stockholder with respect to any shares
covered by the Option until the date of the issuance of a certificate for the
shares for which the Option has been exercised (as evidenced by the appropriate
entry on the books of the Company or of a duly authorized transfer agent of the
Company). No adjustment shall be made for dividends, distributions or other
rights for which the record date is prior to the date such certificate is
issued, except as provided in Section 9. If the Optionee is an Employee, the
Optionee understands and acknowledges that, except as otherwise provided in a
separate, written employment agreement between a Participating Company and the
Optionee, the Optionee’s employment is “at will” and is for no specified term.
Nothing in this Option Agreement shall confer upon the Optionee any right to
continue in the Service of a Participating Company or interfere in any way with
any right of the Participating Company Group to terminate the Optionee’s Service
as an Employee or Consultant, as the case may be, at any time.

 

  11. NOTICE OF SALES UPON DISQUALIFYING DISPOSITION.

The Optionee shall dispose of the shares acquired pursuant to the Option only in
accordance with the provisions of this Option Agreement. In addition, if the
Notice designates this Option as an Incentive Stock Option, the Optionee shall
(a) promptly notify the Chief Financial Officer of the Company if the Optionee
disposes of any of the shares acquired pursuant to the Option within one
(1) year after the date the Optionee exercises all or part of the Option or
within two (2) years after the Date of Option Grant and (b) provide the Company
with a description of the circumstances of such disposition. Until such time as
the Optionee disposes of such shares in a manner consistent with the provisions
of this Option Agreement, unless otherwise expressly authorized by the Company,
the Optionee shall hold all shares acquired pursuant to the Option in the
Optionee’s name (and not in the name of any nominee) for the one-year period
immediately after the exercise of the Option and the two-year period immediately
after Date of Option Grant. At any time during the one-year or two-year periods
set forth above, the Company may place a legend on any certificate representing
shares acquired pursuant to the

 

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Option requesting the transfer agent for the Company’s stock to notify the
Company of any such transfers. The obligation of the Optionee to notify the
Company of any such transfer shall continue notwithstanding that a legend has
been placed on the certificate pursuant to the preceding sentence.

 

  12. LEGENDS.

The Company may at any time place legends referencing any applicable federal,
state or foreign securities law restrictions, and, if applicable, that the
shares were acquired upon exercise of an Incentive Stock Option on all
certificates representing shares of stock subject to the provisions of this
Option Agreement. The Optionee shall, at the request of the Company, promptly
present to the Company any and all certificates representing shares acquired
pursuant to the Option in the possession of the Optionee in order to carry out
the provisions of this Section.

 

  13. LOCK-UP AGREEMENT.

The Optionee hereby agrees that in the event of any underwritten public offering
of stock, including an initial public offering of stock, made by the Company
pursuant to an effective registration statement filed under the Securities Act,
the Optionee shall not offer, sell, contract to sell, pledge, hypothecate, grant
any option to purchase or make any short sale of, or otherwise dispose of any
shares of stock of the Company or any rights to acquire stock of the Company for
such period of time from and after the effective date of such registration
statement as may be established by the underwriter for such public offering;
provided, however, that such period of time shall not exceed one hundred eighty
(180) days from the effective date of the registration statement to be filed in
connection with such public offering (or such longer period, not to exceed
eighteen (18) days after the expiration of the one hundred eighty (180) day
period, as the underwriters or the Company shall request in order to facilitate
compliance with NASD Rule 2711). The foregoing limitation shall not apply to
shares registered in the public offering under the Securities Act. The Optionee
further agrees to execute and deliver such other agreements as may be reasonably
requested by the Company and/or the underwriter(s) that are consistent with the
foregoing or that are necessary to give further effect thereto. In order to
enforce the foregoing covenant, the Company may impose stop-transfer
instructions with respect to any shares of stock of the Company or any rights to
acquire stock of the Company held by the Optionee until the end of such period.

 

  14. RESTRICTIONS ON TRANSFER OF SHARES.

No shares acquired upon exercise of the Option may be sold, exchanged,
transferred (including, without limitation, any transfer to a nominee or agent
of the Optionee), assigned, pledged, hypothecated or otherwise disposed of,
including by operation of law, in any manner which violates any of the
provisions of this Option Agreement, and any such attempted disposition shall be
void. The Company shall not be required (a) to transfer on its books any shares
which will have been transferred in violation of any of the provisions set forth
in this Option Agreement or (b) to treat as owner of such shares or to accord
the right to vote as such owner or to pay dividends to any transferee to whom
such shares will have been so transferred.

 

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  15. MISCELLANEOUS PROVISIONS.

15.1        Termination for Cause.  If the Optionee’s Service is terminated for
Cause (as defined below), then the Optionee shall immediately forfeit all rights
to the Option and the Option, including any vested portion, shall immediately
expire. For purposes of this Option Agreement, “Cause” means that the Optionee
has committed or engaged in: (a) willful misconduct, gross negligence, theft,
fraud, or other illegal or dishonest conduct, any of which are considered to be
materially harmful to the Company; (b) refusal, unwillingness, failure, or
inability to perform material job duties or habitual absenteeism; or
(c) violation of fiduciary duty, violation of any duty of loyalty, or material
breach of any material term of any contract between the Optionee and the
Company.

15.2        Binding Effect.  Subject to the restrictions on transfer set forth
herein, this Option Agreement shall inure to the benefit of and be binding upon
the parties hereto and their respective heirs, executors, administrators,
successors and assigns.

15.3        Termination or Amendment.  The Board may terminate or amend the Plan
or the Option at any time; provided, however, that except as provided in
Section 8 in connection with a Change in Control, no such termination or
amendment may adversely affect the Option or any unexercised portion hereof
without the consent of the Optionee unless such termination or amendment is
necessary to comply with any applicable law or government regulation or is
required to enable the Option, if designated an Incentive Stock Option in the
Notice, to qualify as an Incentive Stock Option. No amendment or addition to
this Option Agreement shall be effective unless in writing.

15.4        Notices.  Any notice required or permitted hereunder shall be given
in writing and shall be deemed effectively given (except to the extent that this
Option Agreement provides for effectiveness only upon actual receipt of such
notice) upon personal delivery or upon deposit in the United States Post Office,
by registered or certified mail, with postage and fees prepaid, addressed to the
other party at the address shown below that party’s signature on the Notice or
at such other address as such party may designate in writing from time to time
to the other party.

15.5        Integrated Agreement.  The Notice, this Option Agreement and the
Plan constitute the entire understanding and agreement of the Optionee and the
Participating Company Group with respect to the subject matter contained herein
or therein and supersedes any prior agreements, understandings, restrictions,
representations, or warranties among the Optionee and the Participating Company
Group with respect to such subject matter other than those as set forth or
provided for herein or therein. To the extent contemplated herein or therein,
the provisions of the Notice and the Option Agreement shall survive any exercise
of the Option and shall remain in full force and effect.

15.6        Applicable Law.  This Option Agreement shall be governed by the laws
of the State of Delaware as such laws are applied to agreements between Delaware
residents entered into and to be performed entirely within the State of
Delaware.

 

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15.7        Counterparts.  The Notice may be executed in counterparts, each of
which shall be deemed an original, but all of which together shall constitute
one and the same instrument.

 

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LOGO [g89145ex10-6pg11.jpg]    Incentive Stock Option              Optionee:
                                

LOGO [g89145ex10-6pg11.jpg]    Nonstatutory Stock Option        Date:
                                       

STOCK OPTION EXERCISE NOTICE

ARCA biopharma, Inc.

Attention: Chief Financial Officer

8001 Arista Place, Suite 200

Broomfield, CO 80021

Ladies and Gentlemen:

1.            Option.  I was granted an option (the “Option”) to purchase shares
of the common stock (the “Option Shares”) of ARCA biopharma, Inc. (the
“Company”) pursuant to the Nuvelo, Inc. 2004 Equity Incentive Plan, as amended
to date (the “Plan”), my Notice of Grant of Stock Option (the “Notice”) and my
Stock Option Agreement (the “Option Agreement”) as follows:

 

Grant Number:

   ________________

Date of Option Grant:

   ________________

Number of Option Shares:

   ________________

Exercise Price per Option Share:

   $________________

2.            Exercise of Option.  I hereby elect to exercise the Option to
purchase the following number of Option Shares:

 

Total Option Shares Purchased:

     ________________

Total Exercise Price (Total Shares X Price per Option Share)

   $ ________________

3.            Payments.  I enclose payment in full of the total exercise price
for the Option Shares in the following form(s), as authorized by my Option
Agreement.

 

¨  Cash:

  ________________

¨  Check:

  ________________

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¨  Tender of Company Stock:    Contact Plan Administrator ¨  Cashless exercise:
   Contact Plan Administrator

4.            Tax Withholding.  Subject to the Option Agreement, I authorize
payroll withholding and otherwise will make adequate provision for the federal,
state, local and foreign tax withholding obligations of the Company, if any, in
connection with the Option.

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5.            Optionee Information.

 

My address is:   

 

  

 

My Social Security Number is:   

 

  

6.            Notice of Disqualifying Disposition.  If the Option is an
Incentive Stock Option, I agree that I will promptly notify the Chief Financial
Officer of the Company if I transfer any of the Option Shares within one
(1) year from the date I exercise all or part of the Option or within two
(2) years of the Date of Option Grant.

7.            Binding Effect.  I agree that the Option Shares are being acquired
in accordance with and subject to the terms, provisions and conditions of the
Option Agreement, to all of which I hereby expressly assent. This agreement
shall inure to the benefit of and be binding upon my heirs, executors,
administrators, successors and assigns.

I understand that I am purchasing the Option Shares pursuant to the terms of the
Plan, the Notice and my Option Agreement, copies of which I have received and
carefully read and understand.

 

Very truly yours,  

 

  (Signature)  

Receipt of the above is hereby acknowledged.

 

ARCA biopharma, Inc.   By:  

 

 

Title:  

 

 

Dated:  

 

 

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

ARCA biopharma, Inc.

NOTICE OF GRANT OF STOCK OPTION

                         (the “Optionee”) has been granted an option (the
“Option”) to purchase certain shares of Stock of ARCA biopharma, Inc. (f/k/a
Nuvelo, Inc.) pursuant to the Nuvelo, Inc. 2004 Equity Incentive Plan, as
amended to date (as amended, the “Plan”), as follows:

 

Date of Option Grant:                       , 2009 Option Number:  
2009-             Number of Option Shares:   _____________ Exercise Price:  
$             per share Vesting Start Date:   _________________ Option
Expiration Date:                           , 2019 Tax Status of Option:  
Incentive Stock Option

The total Exercise Price of the Option Shares granted is $                    .

This Option shall vest as to 1/48th of the total number of Option Shares on each
monthly anniversary of the Vesting Start Date, provided the Optionee remains in
Service on each such date. In addition, if the United States Food and Drug
Administration approves the New Drug Application for Gencaro (the “FDA
Approval”), and provided the Optionee remains in Service on the date of the FDA
Approval, and if fewer than 50% of the Option Shares have become vested by such
date, the vesting of the Option shall be accelerated such that, on the date of
the FDA Approval, this Option shall be vested as to an aggregate of 50% of the
total number of Option Shares subject to this Option, with the balance of the
Option Shares vesting thereafter on the original vesting schedule described
above. In addition, the vesting of the Option Shares shall be subject to
acceleration upon a Change in Control pursuant to Section 8 of the attached
Stock Option Agreement.

In all cases, on any given vesting date, the number of Option Shares becoming
vested on that date will be rounded to the nearest whole number. The maximum
number of Option Shares that can vest and become exercisable pursuant to this
Option is the total number of Option Shares set forth above. This Option shall
be exercisable as to vested Option Shares as provided in the Stock Option
Agreement.

Unless otherwise defined herein, capitalized terms shall have the meanings
assigned to such terms in the Stock Option Agreement or the Plan.

By their signatures below, the Company and the Optionee agree that the Option is
governed by this Notice of Grant of Stock Option and by the provisions of the
Plan and the attached Stock Option Agreement. The Optionee acknowledges receipt
of copies of the Plan and the Stock Option Agreement represents that the
Optionee has read and is familiar with their provisions, and hereby accepts the
Option subject to all of their terms and conditions. The Optionee also
acknowledges receipt of a copy of the Plan prospectus.

 

ARCA biopharma, Inc.     OPTIONEE   By:  

 

   

 

            Patrick M. Wheeler     Signature   Its:  

        Senior VP, Finance

   

 

        Date  

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

Address:   

8001 Arista Place, Suite 200

              

Broomfield, CO 80021

      Address:   

 

              

 

  

ATTACHMENTS:        Stock Option Agreement and Exercise Notice (in hard or soft
copy).