Document:

Exhibit 10.18

 

REVIVA PHARMACEUTICALS, INC.

2006 EQUITY INCENTIVE PLAN

STOCK OPTION AGREEMENT

 

This Stock Option Agreement
(the “Agreement”) is made and entered into as of the Date of Grant set forth below (the “Date
of Grant”) by and between Reviva Pharmaceuticals, Inc., a Delaware corporation (the “Company”),
and the participant named below (the “Participant”).

 

Capitalized terms not
defined herein shall have the meaning ascribed to them in the Company’s 2006 Equity Incentive Plan (the “Plan”).

 

	Participant:	 	 
	 	 	 
	Participant’s Address:	 	 
	 	 	 
	Social Security Number:	 	 
	 	 	 
	Total Option Shares:	 	 
	 	 	 
	Exercise Price Per Share:	 	 
	 	 	 
	Date of Grant:	 	 
	 	 	 
	First Vesting Date:	 	 
	 	 	 
	Expiration Date:	 	 
	 	(unless earlier terminated under Section 5.6 of
the Plan)	 

 

	Classification of Participant:	[  ] Exempt Employee
	 	[  ] Nonexempt Employee
	 	[  ] Independent Contractor
	 	 

 

	Type of Stock Option:	[  ] Incentive Stock Option	[  ] Nonqualified Stock Option

 

1.            GRANT
OF OPTION. The Company hereby grants to Participant an option (this “Option”)
to purchase the total number of shares of Common Stock, $0.0001 par value per share, of the Company set forth above as Total Option
Shares (the “Shares”) at the Exercise Price Per Share set forth above (the “Exercise Price”),
subject to all of the terms and conditions of this Agreement and the Plan. If designated as an Incentive Stock Option above, the
Option is intended to qualify as an “incentive stock option” (an “ISO”) within the meaning
of Section 422 of the Internal Revenue Code of 1986, as amended (the “Code”), except that if on
the date of grant the Participant is not subject to U.S. income tax, then this Option shall be an NQSO.

 

2.            EXERCISE
PERIOD.

 

2.1          Exercise
Period of Option. Provided Participant continues to provide services as an employee, officer, director or consultant to
the Company or any Subsidiary or Parent of the Company, the Option will become vested and exercisable as to portions of the Shares
as follows: (i) this Option shall not vest nor be exercisable with respect to any of the Shares until the First Vesting Date
set forth on the first page of this Agreement (the “First Vesting Date”); (ii) on the six
month anniversary of the First Vesting Date, the Option will become vested and exercisable as to 1/8th of the Total Option Shares;
and (iii) thereafter on the same day of each succeeding calendar month (or if there is no such day in any month, then the
last day of such calendar month) the Option will become vested and exercisable as to an additional 1/48th of the remaining Shares
until the Shares are vested with respect to 100% of the Shares. If application of the vesting percentage causes a fractional share,
such share shall be rounded down to the nearest whole share for each month except for the last month in such vesting period, at
the end of which last month this Option shall become vested for the full remainder of the Shares.

 

     

     

    

 

2.2          Vesting
of Options. Shares that are vested pursuant to the schedule set forth in Section 2.1
are “Vested Shares.” Shares that are not vested pursuant to the schedule set forth in Section 2.1
are “Unvested Shares.”

 

2.3          Expiration.
The Option shall expire on the Expiration Date set forth above or earlier as provided in Section 3 below or pursuant to Section 5.6
of the Plan.

 

3.           TERMINATION.

 

3.1          Termination
for Any Reason Except Death, Disability or Cause. If Participant is Terminated for
any reason except death, Disability or for Cause, the Option, to the extent (and only to the extent) that it would have been exercisable
by Participant on the Termination Date, may be exercised by Participant no later than three (3) months after the Termination
Date, but in any event no later than the Expiration Date.

 

3.2          Termination
Because of Death or Disability. If Participant is Terminated because of death or Disability of Participant (or Participant
dies within three (3) months of Termination when Termination is for any reason other than Participant’s Disability
or for Cause), the Option, to the extent that it is exercisable by Participant on the Termination Date, may be exercised by Participant
(or Participant’s legal representative) no later than ninety (90) days after the Termination Date, but in any event no later
than the Expiration Date. Any exercise beyond

 

		(i)	three (3) months after the Termination Date when the Termination is for any reason other than
the Participant’s death or disability, within the meaning of Section 22(e)(3) of the Code; or

 

		(ii)	twelve (12) months after the Termination Date when the termination is for Participant’s disability,
within the meaning of Section 22(e)(3) of the Code, is deemed to be an NQSO.

 

3.3          Termination
for Cause. If the Participant is terminated for Cause, the Participant may exercise
such Participant’s Options, but not to an extent greater than such Options are exercisable as to Vested Shares upon the Termination
Date and Participant’s Options shall expire on such Participant’s Termination Date, or at such later time and on such
conditions as are determined by the Committee.

 

3.4          No
Obligation to Employ. Nothing in the Plan or this Agreement shall confer on Participant
any right to continue in the employ of, or other relationship with, the Company or any Parent or Subsidiary of the Company, or
limit in any way the right of the Company or any Parent or Subsidiary of the Company to terminate Participant’s employment
or other relationship at any time, with or without Cause.

 

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4.           MANNER
OF EXERCISE.

 

4.1          Stock
Option Exercise Agreement. To exercise this Option, Participant (or in the case of exercise after Participant’s
death or incapacity, Participant’s executor, administrator, heir or legatee, as the case may be) must deliver to the Company
an executed stock option exercise agreement (the “Exercise Agreement”) in the form of stock option exercise
agreement then in use by the Company, a copy of which agreement’s current form has been attached hereto as Exhibit A,
which stock option exercise agreement shall set forth, inter alia, (i) Participant’s election to exercise the
Option, (ii) the number of Shares being purchased, (iii) any restrictions imposed on the Shares and (iv) any representations,
warranties and agreements regarding Participant’s investment intent and access to information as may be required by the
Company to comply with applicable securities laws. If someone other than Participant exercises the Option, then such person must
submit documentation reasonably acceptable to the Company verifying that such person has the legal right to exercise the Option
and such person shall be subject to all of the restrictions contained herein as if such person were the Participant.

 

4.2          Limitations
on Exercise. The Option may not be exercised unless such exercise is in compliance
with all applicable federal and state securities laws, as they are in effect on the date of exercise. The Option may not be exercised
as to fewer than one hundred (100) Shares unless it is exercised as to all Shares as to which the Option is then exercisable.

 

4.3          Payment.
The Exercise Agreement shall be accompanied by full payment of the Exercise Price for the shares being purchased in cash (by check),
or where permitted by law and by the Committee:

 

(a)           by
cancellation of indebtedness of the Company to the Participant;

 

(b)          by
surrender of fully-paid, nonassessable and vested shares of the Company’s Common Stock that (i) either (A) have
been owned by Participant for more than six (6) months and for which the Company has received “full payment of the purchase
price” within the meaning of SEC Rule 144 (and, if such shares were purchased from the Company by use of a promissory
note, such note has been fully paid with respect to such shares) or (B) were obtained by Participant in the open public market;
and (ii) are clear of all liens, claims, encumbrances or security interests;

 

(c)           by
waiver of compensation due or accrued to Participant for services rendered;

 

(d)          provided
that a public market for the Company’s stock exists:

 

		(i)	through a “same day sale” commitment from Participant and a broker-dealer that is a
member of the National Association of Securities Dealers (an “NASD Dealer”) whereby Participant irrevocably
elects to exercise the Option and to sell a portion of the Shares so purchased sufficient to pay for the total Exercise Price and
whereby the NASD Dealer irrevocably commits upon receipt of such Shares to forward the total Exercise Price directly to the Company,
or (ii) through a “margin” commitment from Participant and an NASD Dealer whereby Participant irrevocably elects
to exercise the Option and to pledge the Shares so purchased to the NASD Dealer in a margin account as security for a loan from
the NASD Dealer in the amount of the total Exercise Price, and whereby the NASD Dealer irrevocably commits upon receipt of such
Shares to forward the total Exercise Price directly to the Company;

 

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(e)            any
other form of consideration approved by the Committee; or

 

(f)            by
any combination of the foregoing.

 

4.4         Tax
Withholding. Prior to the issuance of the Shares upon exercise of the Option, Participant
must pay or provide for any applicable federal, state and local withholding obligations of the Company. If the Committee permits,
Participant may provide for payment of withholding taxes upon exercise of the Option by requesting that the Company retain the
minimum number of Shares with a Fair Market Value equal to the minimum amount of taxes required to be withheld; but in no event
will the Company withhold Shares if such withholding would result in adverse accounting consequences to the Company. In such case,
the Company shall issue the net number of Shares to the Participant by deducting the Shares retained from the Shares issuable upon
exercise.

 

4.5          Issuance
of Shares. Provided that the Exercise Agreement and payment are in form and substance
satisfactory to counsel for the Company, the Company shall issue the Shares registered in the name of Participant, Participant’s
authorized assignee, or Participant’s legal representative, and shall deliver certificates representing the Shares with the
appropriate legends affixed thereto.

 

5.           NOTICE
OF DISQUALIFYING DISPOSITION OF ISO SHARES. If the Option is an ISO, and if Participant
sells or otherwise disposes of any of the Shares acquired pursuant to the ISO on or before the later of (i) the date two (2) years
after the Date of Grant and (ii)     the date one (1) year
after the purchase of such Shares by Participant upon exercise of the Option, Participant shall immediately notify the Company
in writing of such disposition. Participant agrees that Participant may be subject to income tax withholding by the Company
on the compensation income recognized by Participant from the early disposition by payment in cash or out of the current wages
or other compensation payable to Participant.

 

6.           COMPLIANCE
WITH LAWS AND REGULATIONS. The Plan and this Agreement are intended to comply with
Section 25102(o) of the California Corporations Code and any regulations relating thereto. Any provision of this
Agreement that is inconsistent with Section 25102(o) or any regulations relating thereto shall, without further act or
amendment by the Company or the Board, be reformed to comply with the requirements of Section 25102(o) and any regulations
relating thereto. The exercise of the Option and the issuance and transfer of Shares shall be subject to compliance by the
Company and Participant with all applicable requirements of federal and state securities laws and with all applicable requirements
of any stock exchange on which the Company’s Common Stock may be listed at the time of such issuance or transfer. Participant
understands that the Company is under no obligation to register or qualify the Shares with the SEC, any state securities commission
or any stock exchange to effect such compliance.

 

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7.            NONTRANSFERABILITY
OF OPTION. The Option may not be transferred in any manner other than by will or by
the laws of descent and distribution, and, with respect to NQSOs, by instrument to an inter vivos or testamentary trust in which
the options are to be passed to beneficiaries upon the death of the trustor (settlor), or by gift to “immediate family”
as that term is defined in 17 C.F.R. 240.16a-1(e), and may be exercised during the lifetime of Participant only by Participant
or in the event of Participant’s incapacity, by Participant’s legal representative. The terms of the Option and the
Plan shall be binding upon the executors, administrators, successors and assigns of Participant.

 

8.            COMPANY’S
RIGHT OF FIRST REFUSAL. Before any Vested Shares held by Participant or any transferee
of such Vested Shares may be sold or otherwise transferred (including without limitation a transfer by gift or operation of law),
the Company and/or its assignee(s) shall have an assignable right of first refusal to purchase the Vested Shares to be sold
or transferred on the terms and conditions set forth in the Exercise Agreement (the “Right of First Refusal”).
The Company’s Right of First Refusal will terminate when the Company’s securities become publicly traded. Unvested
Shares may not be sold or otherwise transferred without the Company’s prior written consent.

 

9.            TAX
CONSEQUENCES. Set forth below is a brief summary as of the Effective Date of the Plan
of some of the federal and California tax consequences of exercise of the Option and disposition of the Shares. THIS SUMMARY
IS NECESSARILY INCOMPLETE, AND THE TAX LAWS AND REGULATIONS ARE SUBJECT TO CHANGE. PARTICIPANT SHOULD CONSULT A TAX ADVISER BEFORE
EXERCISING THE OPTION OR DISPOSING OF THE SHARES.

 

9.1         Exercise
of ISO. If the Option qualifies as an ISO, there will be no regular federal
or California income tax liability upon the exercise of the Option, although the excess, if any, of the Fair Market Value of the
Shares on the date of exercise over the Exercise Price will be treated as a tax preference item for federal alternative minimum
tax purposes and may subject the Participant to the alternative minimum tax in the year of exercise.

 

9.2         Exercise
of Nonqualified Stock Option. If the Option does not qualify as an ISO, there
may be regular federal and California income tax liability upon the exercise of the Option. Participant shall be treated
as having received compensation income (taxable at ordinary income tax rates) equal to the excess, if any, of the Fair Market Value
of the Shares on the date of exercise over the Exercise Price. If Participant is a current or former employee of the Company,
the Company may be required to withhold from Participant’s compensation or collect from Participant and pay to the applicable
taxing authorities an amount equal to a percentage of this compensation income at the time of exercise.

 

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9.3         Disposition
of Shares. The following tax consequences may apply upon disposition of the
Shares:

 

(a)            Incentive
Stock Options. If the Shares are held for more than twelve (12) months after the date of purchase of the Shares pursuant
to the exercise of an ISO and are disposed of more than two (2) years after the Date of Grant, any gain realized on disposition
of the Shares will be treated as long term capital gain for federal and California income tax purposes. If Shares purchased
under an ISO are disposed of within the applicable one (1) year or two (2) year period, any gain realized on such disposition
will be treated as compensation income (taxable at ordinary income rates in the year of the disposition) to the extent of the excess,
if any, of the Fair Market Value of the Shares on the date of exercise over the Exercise Price.

 

(b)           Nonqualified
Stock Options. If the Shares are held for more than twelve (12) months after the date of purchase of the Shares pursuant
to the exercise of an NQSO, any gain realized on disposition of the Shares will be treated as long term capital gain.

 

(c)            Withholding.
The Company may be required to withhold from the Participant’s compensation or collect from the Participant and pay to
the applicable taxing authorities an amount equal to a percentage of this compensation income.

 

10.         PRIVILEGES
OF STOCK OWNERSHIP. Participant shall not have any of the rights of a stockholder
with respect to any Shares until the Shares are issued to Participant.

 

11.         GENERAL
PROVISIONS.

 

11.1       Interpretation.
Any dispute regarding the interpretation of this Agreement shall be submitted by Participant or the Company to the Committee
for review. The resolution of such a dispute by the Committee shall be final and binding on the Company and Participant.

 

11.2       Entire
Agreement. The Plan is incorporated herein by reference. This Agreement and the Plan
constitute the entire agreement and understanding of the parties with respect to the subject matter of this Agreement, and supersede
all prior understandings and agreements, whether oral or written, between or among the parties hereto with respect to the specific
subject matter hereof.

 

11.3       Notices.
Any notice required to be given or delivered to the Company under the terms of this Agreement shall be in writing and addressed
to the Corporate Secretary of the Company at its principal corporate offices or to its facsimile or telecopier number specified
below. Any notice required to be given or delivered to Participant shall be in writing and addressed to Participant at the address,
facsimile or telecopier indicated below or to such other address, facsimile or telecopier as such party may designate in writing
from time to time to the Company. All notices shall be deemed to have been given or delivered upon: (i) personal delivery;
(ii) three (3) days after deposit in the United States mail by certified or registered mail (return receipt requested);
(iii) one (1) business day after deposit with any return receipt express courier (prepaid); or (iv) one (1) business
day after transmission by facsimile or telecopier.

 

11.4       Successors
and Assigns. The Company may assign any of its rights under this Agreement including
its rights to purchase Shares under the Right of First Refusal. No other party to this Agreement may assign, whether voluntarily
or by operation of law, any of its rights and obligations under this Agreement, except with the prior written consent of the Company.
This Agreement shall be binding upon and inure to the benefit of the successors and assigns of the Company. Subject to the restrictions
on transfer set forth herein, this Agreement shall be binding upon Participant and Participant’s heirs, executors, administrators,
legal representatives, successors and assigns.

 

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11.5       Governing
Law. This Agreement shall be governed by and construed in accordance with the laws
of the State of California as such laws are applied to agreements between California residents entered into and to be performed
entirely within California.

 

11.6       Acceptance.
Participant hereby acknowledges receipt of a copy of the Plan and this Agreement. Participant has read and understands the terms
and provisions thereof, and accepts the Option subject to all the terms and conditions of the Plan and this Agreement. Participant
acknowledges that there may be adverse tax consequences upon exercise of the Option or disposition of the Shares and agrees that
Participant shall consult a tax adviser prior to such exercise or disposition.

 

11.7       Further
Assurances. The parties agree to execute such further documents and instruments and
to take such further actions as may be reasonably necessary to carry out the purposes and intent of this Agreement.

 

11.8       Titles
and Headings. The titles, captions and headings of this Agreement are included for
ease of reference only and shall be disregarded in interpreting or construing this Agreement. Unless otherwise specifically stated,
all references herein to “sections” and “exhibits” will mean “sections” and “exhibits”
to this Agreement.

 

11.9       Severability.
If any provision of this Agreement is determined by any court or arbitrator of competent jurisdiction to be invalid, illegal or
unenforceable in any respect, such provision shall be enforced to the maximum extent possible given the intent of the parties hereto.
If such clause or provision cannot be so enforced, such provision shall be stricken from this Agreement and the remainder of this
Agreement shall be enforced as if such invalid, illegal or unenforceable clause or provision had (to the extent not enforceable)
never been contained in this Agreement. Notwithstanding the foregoing, if the value of this Agreement based upon the substantial
benefit of the bargain for any party is materially impaired, which determination as made by the presiding court or arbitrator of
competent jurisdiction shall be binding, then both parties agree to substitute such provision(s) through good faith negotiations.

 

11.10    Counterparts.
This Agreement may be entered into in two or more counterparts, each of which shall be deemed an original and all of which shall
constitute one and the same agreement.

 

11.11     Facsimile
Signatures. This Agreement may be executed and delivered by facsimile or electronically
in portable document format (.pdf) and upon such delivery the facsimile or portable document format (.pdf) signature will be deemed
to have the same effect as if the original signature had been delivered to the other party.

 

[SIGNATURE PAGE FOLLOWS.]

 

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IN WITNESS WHEREOF,
the Company has caused this Stock Option Agreement to be executed by its duly authorized representative and Participant has executed
this Stock Option Agreement effective as of the Date of Grant.

 	REVIVA PHARMACEUTICALS, INC.:	 	PARTICIPANT:

 

	By:	              	 	By:	 
	 	 	 
		 	 
	President and Chief Executive Officer	 	 
	(Please print title)	 	 

 

	Address: 3900 Freedom Circle, Suite 101	 	Address:	 
	Santa Clara, CA  95054	 	
	Fax No.: (408) 904-6270	 	Fax No.:
	Phone No.: (408) 816-1454	 	Phone No.:

 

     

     

    

 

EXHIBIT A

 

FORM OF STOCK OPTION EXERCISE
AGREEMENT

 

     

     

    

 

REVIVA PHARMACEUTICALS, INC.

 

2006 EQUITY INCENTIVE PLAN STOCK OPTION
EXERCISE AGREEMENT

 

This Stock Option Exercise
Agreement (the “Exercise Agreement”) is made and entered into as of ___________________, __________ (the
 “Effective Date”) by and between Reviva Pharmaceuticals, Inc., a Delaware corporation (the “Company”),
and the purchaser named below (the “Purchaser”). Capitalized terms not defined herein shall have the
meanings ascribed to them in the Company’s 2006 Equity Incentive Plan (the “Plan”) or that certain
Stock Option Agreement entered into by and between Purchaser and the Company dated as of the Date of Grant set forth below (the
 “Stock Option Agreement”).

 

	Purchaser:	 	 
	 	 	 
	Purchaser’s Address:	 	 
	 	 	 
	Social Security Number:	 	 
	 	 	 
	Total Number of Shares:	 	 
	 	 	 
	Exercise Price Per Share:	 	 
	 	 	 
	Date of Grant:	 	 
	 	 	 
	First Vesting Date:	 	 
	 	 	 
	Expiration Date:	 	 
	 	(unless earlier terminated under Section 5.6
of the Plan)	 

 

	Type of Stock Option:	[  ] Incentive Stock Option	[  ] Nonqualified Stock Option

 

1.           Exercise
of Option.

 

1.1          Exercise.
Pursuant to exercise of that certain option granted to Purchaser under the Plan and the Stock Option Agreement (the “Option”)
and subject to the terms and conditions of this Exercise Agreement, Purchaser hereby purchases from the Company, and the Company
hereby sells to Purchaser, the Total Number of Shares set forth above (the “Shares”) of the Company’s
Common Stock, $0.0001 par value per share, at the Exercise Price Per Share set forth above (the “Exercise Price”).
As used in this Exercise Agreement, the term “Shares” refers to the Shares purchased under this Exercise
Agreement and includes all securities received (i) in replacement of the Shares, (ii) as a result of stock dividends
or stock splits with respect to the Shares and (iii) all securities received in replacement of the Shares in a merger, recapitalization,
reorganization or similar corporate transaction.

 

1.2          Title
to Shares. The exact spelling of the name(s) under which Purchaser will take title to the Shares is:

 

     

     

    

 

__________________________________________________________________________________________________________________________

 

__________________________________________________________________________________________________________________________

 

Purchaser desires to take title to the Shares as follows:

 

[
]            Individual, as separate
property

[
]            Husband and wife,
as community property 

[
]            Joint Tenants; please
state name of other tenant:

[
]            Other; please specify:

 

1.3           Payment.
Purchaser hereby delivers payment of the Exercise Price in the manner permitted in the Stock Option Agreement as follows (check
and complete as appropriate):

 

[ ]           in
cash (by check) in the amount of $___     , receipt of which
is acknowledged by the Company;

 

[ ]           subject
to prior approval by the Committee, by cancellation of indebtedness of the Company owed to Purchaser in the amount of $ __     ;

 

[
]           subject to prior
approval by the Committee, by delivery of fully-paid, nonassessable and vested shares of the Common Stock of the Company that (i) either
have been (A) owned by Purchaser for more than six (6) months and for which the Company has received “full payment
of the purchase price” within the meaning of SEC Rule 144 (and, if purchased by use of a promissory note, such note
has been fully paid with respect to such vested shares) or (B) obtained by Purchaser in the open public market, and (ii) are
owned by Purchaser free and clear of all liens, claims, encumbrances or security interests, valued at the current Fair Market Value
of $_______ per share; or

 

[ ]           subject
to prior approval by the Committee, by the waiver hereby of compensation due or accrued for services rendered in the amount of
$____     .

 

2.           Delivery.

 

2.1           Deliveries
by Purchaser. Purchaser hereby delivers to the Company (i) an executed copy of this Exercise Agreement, (ii) two
(2) copies of a blank Stock Power and Assignment Separate from Stock Certificate in the form of Exhibit 1 attached
hereto (the “Stock Powers”), both executed by Purchaser (and Purchaser’s spouse, if any), (iii) if
Purchaser is married, a Consent of Spouse in the form of Exhibit 2 attached hereto (the “Spouse Consent”)
executed by Purchaser’s spouse and (iv) the Exercise Price and payment or other provision for any applicable tax obligations
in a form of payment permitted by this Exercise Agreement for the payment of taxes, proof of which payments are attached hereto
as Exhibit 3.

 

2.2           Deliveries
by the Company. Upon its receipt of the Exercise Price, payment or other provision for any applicable tax obligations and all
the documents to be executed and delivered by Purchaser to the Company under Section 2.1, the Company will issue a duly executed
stock certificate evidencing the Shares in the name of Purchaser to be placed in escrow as provided in Section 10 until expiration
or termination of the Company’s Right of First Refusal described in Sections 8, 9 and 10.

 

     

     

    

 

3.           Representations
and Warranties of Purchaser. Purchaser represents and warrants to the Company as follows.

 

3.1           Agrees
to Terms of the Plan. Purchaser has received a copy of the Plan and the Stock Option Agreement, has read and understands the
terms of the Plan, the Stock Option Agreement and this Exercise Agreement, and agrees to be bound by their terms and conditions.
Purchaser acknowledges that there may be adverse tax consequences upon exercise of the Option or disposition of the Shares, and
agrees that Purchaser shall consult a tax adviser prior to such exercise or disposition.

 

3.2           Purchase
for Own Account for Investment. Purchaser is purchasing the Shares for Purchaser’s own account for investment purposes
only and not with a view to, or for sale in connection with, a distribution of the Shares within the meaning of the Securities
Act. Purchaser has no present intention of selling or otherwise disposing of all or any portion of the Shares and no one other
than Purchaser has any beneficial ownership of any of the Shares.

 

3.3           Access
to Information. Purchaser has had access to all information regarding the Company and its present and prospective business,
assets, liabilities and financial condition that Purchaser reasonably considers important in making the decision to purchase the
Shares, and Purchaser has had ample opportunity to ask questions of the Company’s representatives concerning such matters
and this investment.

 

3.4           Understanding
of Risks. Purchaser is fully aware of: (i) the highly speculative nature of the investment in the Shares; (ii) the
financial hazards involved; (iii) the lack of liquidity of the Shares and the restrictions on transferability of the Shares
(e.g., that Purchaser may not be able to sell or dispose of the Shares or use them as collateral for loans); (iv) the
qualifications and backgrounds of the management of the Company; and (v) the tax consequences of investment in the Shares.
Purchaser is capable of evaluating the merits and risks of this investment, has the ability to protect Purchaser’s own interests
in this transaction and is financially capable of bearing a total loss of this investment.

 

3.5           No
General Solicitation. At no time was Purchaser presented with or solicited by any publicly issued or circulated newspaper,
mail, radio, television or other form of general advertising or solicitation in connection with the offer, sale and purchase of
the Shares.

 

4.           Compliance
with Securities Laws.

 

4.1           Compliance
with U.S. Federal Securities Laws. Purchaser understands and acknowledges that the Shares have not been registered with the
SEC under the Securities Act and that, notwithstanding any other provision of the Stock Option Agreement to the contrary, the exercise
of any rights to purchase any Shares is expressly conditioned upon compliance with the Securities Act and all applicable state
securities laws. Purchaser agrees to cooperate with the Company to ensure compliance with such laws.

 

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4.2          Compliance
with California Securities Laws. THE PLAN, THE STOCK OPTION AGREEMENT AND THIS EXERCISE AGREEMENT ARE INTENDED TO COMPLY WITH
SECTION 25102(o) OF THE CALIFORNIA CORPORATIONS CODE AND ANY RULES (INCLUDING COMMISSIONER RULES, IF APPLICABLE)
OR REGULATIONS PROMULGATED THEREUNDER BY THE CALIFORNIA DEPARTMENT OF CORPORATIONS (THE “REGULATIONS”). ANY
PROVISION OF THIS EXERCISE AGREEMENT THAT IS INCONSISTENT WITH SECTION 25102(o) SHALL, WITHOUT FURTHER ACT OR AMENDMENT
BY THE COMPANY OR THE BOARD, BE REFORMED TO COMPLY WITH THE REQUIREMENTS OF SECTION 25102(o). THE SALE OF THE SECURITIES THAT
ARE THE SUBJECT OF THIS EXERCISE AGREEMENT, IF NOT YET QUALIFIED WITH THE CALIFORNIA COMMISSIONER OF CORPORATIONS AND NOT
EXEMPT FROM SUCH QUALIFICATION, IS SUBJECT TO SUCH QUALIFICATION, AND THE ISSUANCE OF SUCH SECURITIES, AND THE RECEIPT OF
ANY PART OF THE CONSIDERATION THEREFOR PRIOR TO SUCH QUALIFICATION IS UNLAWFUL UNLESS THE SALE IS EXEMPT. THE RIGHTS OF THE
PARTIES TO THIS EXERCISE AGREEMENT ARE EXPRESSLY CONDITIONED UPON SUCH QUALIFICATION BEING OBTAINED OR AN EXEMPTION BEING AVAILABLE.

 

5.           Restricted
Securities.

 

5.1          No
Transfer Unless Registered or Exempt. Purchaser understands that Purchaser may not transfer any Shares unless such Shares are
registered under the Securities Act or qualified under applicable state securities laws or unless, in the opinion of counsel to
the Company, exemptions from such registration and qualification requirements are available. Purchaser understands that only the
Company may file a registration statement with the SEC and that the Company is under no obligation to do so with respect to the
Shares. Purchaser has also been advised that exemptions from registration and qualification may not be available or may not permit
Purchaser to transfer all or any of the Shares in the amounts or at the times proposed by Purchaser.

 

5.2          SEC
Rule 144. In addition, Purchaser has been advised that SEC Rule 144 promulgated under the Securities Act, which permits
certain limited sales of unregistered securities, is not presently available with respect to the Shares and, in any event, requires
that the Shares be held for a minimum of six (6) months, and in certain cases one (1) year, after they have been purchased
and paid for (within the meaning of Rule 144). Purchaser understands that Rule 144 may indefinitely restrict transfer
of the Shares so long as Purchaser remains an “affiliate” of the Company or if “current public information”
about the Company (as defined in Rule 144) is not publicly available.

 

6.           Restrictions
on Transfers.

 

6.1          Disposition
of Shares. Purchaser hereby agrees that Purchaser shall make no disposition of the Shares (other than as permitted by this
Exercise Agreement) unless and until:

 

(a)            Purchaser
shall have notified the Company of the proposed disposition and provided a written summary of the terms and conditions of the proposed
disposition;

 

    -3-

     

    

 

(b)           Purchaser
shall have complied with all requirements of this Exercise Agreement applicable to the disposition of the Shares;

 

(c)            Purchaser
shall have provided the Company with written assurances, in form and substance satisfactory to counsel for the Company, that (i) the
proposed disposition does not require registration of the Shares under the Securities Act or (ii) all appropriate actions
necessary for compliance with the registration requirements of the Securities Act or of any exemption from registration available
under the Securities Act (including Rule 144) have been taken; and

 

(d)           Purchaser
shall have provided the Company with written assurances, in form and substance satisfactory to the Company, that the proposed disposition
will not result in the contravention of any transfer restrictions applicable to the Shares pursuant to the provisions of the Regulations
referred to in Section 4.2 hereof.

 

6.2          Restriction
on Transfer. Purchaser shall not transfer, assign, grant a lien or security interest in, pledge, hypothecate, encumber or otherwise
dispose of any of the Shares that are subject to the Company’s Right of First Refusal described below, except as permitted
by this Exercise Agreement.

 

6.3          Transferee
Obligations. Each person (other than the Company) to whom the Shares are transferred by means of one of the permitted transfers
specified in this Exercise Agreement must, as a condition precedent to the validity of such transfer, acknowledge in writing to
the Company that such person is bound by the provisions of this Exercise Agreement and the Plan and that the transferred Shares
are subject to (i) the Company’s Right of First Refusal granted hereunder and (ii) the market stand-off provisions
of Section 7 hereof, to the same extent such Shares would be so subject if retained by the Purchaser.

 

7.            Market
Standoff Agreement. Purchaser agrees in connection with any registration of the Company’s
securities under the Securities Act or other public offering that, upon the request of the Company or the underwriters managing
any public offering of the Company’s securities, Purchaser will not sell or otherwise dispose of any Shares without the prior
written consent of the Company or such managing underwriters, as the case may be, for a period of time (not to exceed one hundred
eighty (180) days) after the effective date of such registration and during such restricted period the Shares shall remain subject
to all restrictions as the Company or the managing underwriters may specify for employee-stockholders generally; provided,
however, that if during the last seventeen (17) days of such restricted period the Company issues an earnings release or
material news or a material event relating to the Company occurs, or prior to the expiration of the restricted period the Company
announces that it will release earnings results during the 16-day period beginning on the last day of the restricted period, then
if required by the underwriters or the Company the restrictions imposed by this Section 7 shall continue to apply until the
expiration of the 18-day period beginning on the issuance of the earnings release or the occurrence of the material news or material
event. In no event shall the restricted period extend beyond two hundred fifteen (215) days after the effective date of
the applicable registration statement. For purposes of this Section 7, the term “Company” shall include
any wholly-owned subsidiary of the Company into which the Company merges or consolidates. In order to enforce the foregoing
covenant, the Company shall have the right to place restrictive legends on the certificates representing the shares subject to
this Section 7 and to impose stop transfer instructions with respect to the Shares until the end of such period. Purchaser
further agrees to enter into any agreement reasonably required by the underwriters to implement the foregoing within any reasonable
timeframe so requested.

 

    -4-

     

    

 

8.           Company’s
Right of First Refusal. Unvested Shares may not be sold or otherwise transferred by
Purchaser without the Company’s prior written consent. Before any Vested Shares held by Purchaser or any permitted
transferee of such Vested Shares (either sometimes referred to herein as the “Holder”) may be sold or
otherwise transferred (including, without limitation, a transfer by gift or operation of law), the Company and/or its assignee(s) will
have a right of first refusal to purchase the Vested Shares to be sold or transferred (the “Offered Shares”)
on the terms and conditions set forth in this Section (the “Right of First Refusal”).

 

8.1           Notice
of Proposed Transfer. The Holder of the Offered Shares will deliver to the Company a written notice (the “Notice”)
stating: (i) the Holder’s bona fide intention to sell or otherwise transfer the Offered Shares; (ii) the name and
address of each proposed purchaser or other transferee (the “Proposed Transferee”); (iii) the number
of Offered Shares to be transferred to each Proposed Transferee; (iv) the bona fide cash price or other consideration for
which the Holder proposes to transfer the Offered Shares (the “Offered Price”); and (v) that the
Holder acknowledges this Notice is an offer to sell the Offered Shares to the Company and/or its assignee(s) pursuant to the
Company’s Right of First Refusal at the Offered Price as provided for in this Exercise Agreement.

 

8.2           Exercise
of Right of First Refusal. At any time within thirty (30) days after the Company’s effective receipt of the Notice,
the Company and/or its assignee(s) may, by giving written notice to the Holder, elect to purchase all or less than all of
the Offered Shares proposed to be transferred to any one or more of the Proposed Transferees named in the Notice, at the purchase
price, determined as specified below.

 

8.3           Purchase
Price. The purchase price for the Offered Shares purchased under this Section will be the Offered Price, provided
that if the Offered Price consists of no legal consideration (as, for example, in the case of a transfer by gift) the purchase
price will be the fair market value of the Offered Shares as determined in good faith by the Company’s Board of Directors.
If the Offered Price includes consideration other than cash, then the value of the non- cash consideration, as determined in
good faith by the Company’s Board of Directors, will conclusively be deemed to be the cash equivalent value of such non-cash
consideration.

 

8.4           Payment.
Payment of the purchase price for the Offered Shares will be payable, at the option of the Company and/or its assignee(s) (as
applicable), by check, wire transfer or by cancellation of all or a portion of any outstanding purchase money indebtedness owed
by the Holder to the Company (or to such assignee, in the case of a purchase of Offered Shares by such assignee) or by any combination
thereof. The purchase price will be paid without interest within sixty (60) days after the Company’s effective receipt
of the Notice, or, at the option of the Company and/or its assignee(s), in the manner and at the time(s) set forth in the
Notice.

 

8.5           Holder’s
Right to Transfer. If all of the Offered Shares proposed in the Notice to be transferred to a given Proposed Transferee
are not purchased by the Company and/or its assignee(s) as provided in this Section, then the Holder may sell or otherwise
transfer such Offered Shares to such Proposed Transferee at the Offered Price or at a higher price, provided that (i) such
sale or other transfer is consummated within one hundred twenty (120) days after the effective date of the Notice, (ii) any
such sale or other transfer is effected in compliance with all applicable securities laws and (iii) such Proposed Transferee
agrees in writing that the provisions of this Exercise Agreement and the Plan will continue to apply to the Offered Shares in the
hands of such Proposed Transferee. If the Offered Shares described in the Notice are not transferred to a Proposed Transferee
within such one hundred twenty (120) day period, then a new Notice must be given to the Company pursuant to which the Company will
again be offered the Right of First Refusal before any Shares held by the Holder may be sold or otherwise transferred.

 

    -5-

     

    

 

8.6           Exempt
Transfers. Notwithstanding anything to the contrary in this Section, the following transfers of Vested Shares will be
exempt from the Right of First Refusal: (i) the transfer of any or all of the Vested Shares during Purchaser’s lifetime
by gift or on Purchaser’s death by will or intestacy to Purchaser’s “Immediate Family” (as defined below)
or to a trust for the benefit of Purchaser or Purchaser’s Immediate Family, provided that each transferee or other recipient
agrees in a writing satisfactory to the Company that the provisions of this Exercise Agreement and the Plan will continue to apply
to the transferred Vested Shares in the hands of such transferee or other recipient; (ii) any transfer of Vested Shares made
pursuant to a statutory merger or statutory consolidation of the Company with or into another corporation or corporations except
that the Right of First Refusal will continue to apply thereafter to such Vested Shares, in which case the surviving corporation
of such merger or consolidation shall succeed to the rights of the Company under this Section unless the agreement of merger
or consolidation expressly otherwise provides; or (iii) any transfer of Vested Shares pursuant to the winding up and dissolution
of the Company. As used herein, the term “Immediate Family” will mean Purchaser’s spouse,
the lineal descendant or antecedent, father, mother, brother or sister, child, adopted child, grandchild or adopted grandchild
of the Purchaser or the Purchaser’s spouse, or the spouse of any of the above.

 

8.7           Termination
of Right of First Refusal. The Right of First Refusal will terminate as to all Shares on the effective date of the first
sale of Common Stock of the Company to the general public pursuant to a registration statement filed with and declared effective
by the SEC under the Securities Act (other than a registration statement relating solely to the issuance of Common Stock pursuant
to a business combination or an employee incentive or benefit plan).

 

8.8           Encumbrances
on Vested Shares. Purchaser may grant a lien or security interest in, or pledge, hypothecate or encumber Vested Shares
only if each party to whom such lien or security interest is granted, or to whom such pledge, hypothecation or other encumbrance
is made, agrees in a writing satisfactory to the Company that: (i) such lien, security interest, pledge, hypothecation or
encumbrance will not apply to such Vested Shares after they are acquired by the Company and/or its assignees under this Section;
and (ii) the provisions of this Exercise Agreement and the Plan will continue to apply to such Vested Shares in the hands
of such party and any transferee of such party. Purchaser may not grant a lien or security interest in, or pledge, hypothecate
or encumber, any Unvested Shares.

 

9.           Rights
as a Stockholder. Subject to the terms and conditions of this Exercise Agreement,
Purchaser will have all of the rights of a stockholder of the Company with respect to the Shares from and after the date that Shares
are issued to Purchaser until such time as Purchaser disposes of the Shares or the Company and/or its assignee(s) exercise(s) the
Right of First Refusal. Upon an exercise of the Right of First Refusal, Purchaser will have no further rights as a holder
of the Shares so purchased upon such exercise, other than the right to receive payment for the Shares so purchased in accordance
with the provisions of this Exercise Agreement, and, if applicable, Purchaser will promptly surrender the stock certificate(s) evidencing
the Shares so purchased to the Company for transfer or cancellation.

 

    -6-

     

    

 

10.         Escrow.
As security for Purchaser’s faithful performance of this Exercise Agreement, Purchaser
agrees, immediately upon receipt of the stock certificate(s) evidencing the Shares, to deliver such certificate(s), together
with the Stock Powers executed by Purchaser and by Purchaser’s spouse, if any (with the transferee, certificate number, date
and number of Shares left blank), to the Secretary of the Company or other designee of the Company (the “Escrow Holder”),
who is hereby appointed to hold such certificate(s) and Stock Powers in escrow and to take all such actions and to effectuate
all such transfers and/or releases of such Shares as are in accordance with the terms of this Exercise Agreement. Purchaser
and the Company agree that Escrow Holder will not be liable to any party to this Exercise Agreement (or to any other party) for
any actions or omissions unless Escrow Holder is grossly negligent or intentionally fraudulent in carrying out the duties of Escrow
Holder under this Exercise Agreement. Escrow Holder may rely upon any letter, notice or other document executed with any
signature purported to be genuine and may rely on the advice of counsel and obey any order of any court with respect to the transactions
contemplated by this Exercise Agreement. The Shares will be released from escrow upon termination of the Right of First
Refusal.

 

11.         Restrictive
Legends and Stop-Transfer Orders.

 

11.1         Legends.
Purchaser understands and agrees that the Company will place the legends set forth below or similar legends on any stock certificate(s) evidencing
the Shares, together with any other legends that may be required by state or U.S. Federal securities laws, the Company’s
Certificate of Incorporation or Bylaws, any other agreement between Purchaser and the Company or any agreement between Purchaser
and any third party:

 

THE SECURITIES REPRESENTED HEREBY
HAVE NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED (THE “SECURITIES ACT”), OR UNDER THE SECURITIES
LAWS OF CERTAIN STATES. THESE SECURITIES ARE SUBJECT TO RESTRICTIONS ON TRANSFERABILITY AND RESALE AND MAY NOT BE TRANSFERRED
OR RESOLD EXCEPT AS PERMITTED UNDER THE SECURITIES ACT AND APPLICABLE STATE SECURITIES LAWS, PURSUANT TO REGISTRATION OR EXEMPTION
THEREFROM. INVESTORS SHOULD BE AWARE THAT THEY MAY BE REQUIRED TO BEAR THE FINANCIAL RISKS OF THIS INVESTMENT FOR AN INDEFINITE
PERIOD OF TIME. THE ISSUER OF THESE SECURITIES MAY REQUIRE AN OPINION OF COUNSEL IN FORM AND SUBSTANCE SATISFACTORY TO
THE ISSUER TO THE EFFECT THAT ANY PROPOSED TRANSFER OR RESALE IS IN COMPLIANCE WITH THE SECURITIES ACT AND ANY APPLICABLE STATE
SECURITIES LAWS.

 

    -7-

     

    

 

THE SHARES REPRESENTED BY THIS
CERTIFICATE ARE SUBJECT TO CERTAIN RESTRICTIONS ON PUBLIC RESALE AND TRANSFER, INCLUDING THE RIGHT OF FIRST REFUSAL HELD BY
THE ISSUER AND/OR ITS ASSIGNEE(S) AS SET FORTH IN A STOCK OPTION EXERCISE AGREEMENT BETWEEN THE ISSUER AND THE ORIGINAL HOLDER
OF THESE SHARES, A COPY OF WHICH MAY BE OBTAINED AT THE PRINCIPAL OFFICE OF THE ISSUER. SUCH PUBLIC SALE AND TRANSFER RESTRICTIONS, INCLUDING
THE RIGHT OF FIRST REFUSAL, ARE BINDING ON TRANSFEREES OF THESE SHARES.

 

THE SHARES REPRESENTED BY THIS
CERTIFICATE ARE SUBJECT TO A 180 DAY MARKET STANDOFF RESTRICTION AS SET FORTH IN A CERTAIN STOCK OPTION EXERCISE AGREEMENT BETWEEN
THE ISSUER AND THE ORIGINAL HOLDER OF THESE SHARES, A COPY OF WHICH MAY BE OBTAINED AT THE PRINCIPAL OFFICE OF THE ISSUER.
AS A RESULT OF SUCH AGREEMENT, THESE SHARES MAY NOT BE TRADED PRIOR TO 180 DAYS AFTER THE EFFECTIVE DATE OF ANY PUBLIC OFFERING
OF THE COMMON STOCK OF THE ISSUER HEREOF. SUCH RESTRICTION IS BINDING ON TRANSFEREES OF THESE SHARES.

 

11.2        Stop-Transfer
Instructions. Purchaser agrees that, to ensure compliance with the restrictions imposed by this Exercise Agreement,
the Company may issue appropriate “stop-transfer” instructions to its transfer agent, if any, and if the Company transfers
its own securities, it may make appropriate notations to the same effect in its own records.

 

11.3        Refusal
to Transfer. The Company will not be required (i) to transfer on its books any Shares that have been sold or otherwise
transferred in violation of any of the provisions of this Exercise Agreement or (ii) to treat as owner of such Shares, or
to accord the right to vote or pay dividends to any purchaser or other transferee to whom such Shares have been so transferred.

 

12.         Tax
Consequences. PURCHASER UNDERSTANDS THAT PURCHASER MAY SUFFER ADVERSE TAX CONSEQUENCES
AS A RESULT OF PURCHASER’S PURCHASE OR DISPOSITION OF THE SHARES. PURCHASER REPRESENTS: (i) THAT PURCHASER HAS
CONSULTED WITH ANY TAX ADVISER THAT PURCHASER DEEMS ADVISABLE IN CONNECTION WITH THE PURCHASE OR DISPOSITION OF THE SHARES AND
(ii) THAT PURCHASER IS NOT RELYING ON THE COMPANY NOR ITS REPRESENTATIVES FOR ANY TAX ADVICE. Set forth below is a
brief summary as of the date the Plan was adopted by the Board of some of the U.S. Federal and California tax consequences of exercise
of the Option and disposition of the Shares. THIS SUMMARY IS NECESSARILY INCOMPLETE, AND THE TAX LAWS AND REGULATIONS ARE
SUBJECT TO CHANGE. PURCHASER SHOULD CONSULT HIS OR HER OWN TAX ADVISER BEFORE EXERCISING THE OPTION OR DISPOSING OF THE
SHARES.

 

    -8-

     

    

 

12.1        Exercise
of Incentive Stock Option. If the Option qualifies as an ISO, there will be no regular U.S. Federal income tax liability
or California income tax liability upon the exercise of the Option, although the excess, if any, of the Fair Market Value of the
Shares on the date of exercise over the Exercise Price will be treated as a tax preference item for U.S. Federal alternative minimum
tax purposes and may subject Purchaser to the alternative minimum tax in the year of exercise.

 

12.2        Exercise
of Nonqualified Stock Option. If the Option does not qualify as an ISO, there may be regular U.S. Federal income tax
liability and California income tax liability upon the exercise of the Option. Purchaser will be treated as having received
compensation income (taxable at ordinary income tax rates) equal to the excess, if any, of the Fair Market Value of the Shares
on the date of exercise over the Exercise Price. If Purchaser is or was an employee of the Company, the Company may be required
to withhold from Purchaser’s compensation or collect from Purchaser and pay to the applicable taxing authorities an amount
equal to a percentage of this compensation income at the time of exercise.

 

12.3        Disposition
of Shares. The following tax consequences may apply upon disposition of the Shares.

 

(a)            Incentive
Stock Options. If the Shares are held for more than twelve (12) months after the date of purchase of the Shares pursuant
to the exercise of an ISO and are disposed of more than two (2) years after the Date of Grant, any gain realized on disposition
of the Shares will be treated as long term capital gain for federal and California income tax purposes. If Shares purchased
under an ISO are disposed of within the applicable one (1) year or two (2) year period, any gain realized on such disposition
will be treated as compensation income (taxable at ordinary income rates) to the extent of the excess, if any, of the Fair Market
Value of the Shares on the date of exercise over the Exercise Price.

 

(b)           Nonqualified
Stock Options. If the Shares are held for more than twelve (12) months after the date of purchase of the Shares pursuant
to the exercise of an NQSO, any gain realized on disposition of the Shares will be treated as long term capital gain.

 

(c)            Withholding.
The Company may be required to withhold from the Purchaser’s compensation or collect from the Purchaser and pay to the
applicable taxing authorities an amount equal to a percentage of this compensation income.

 

13.         Compliance
with Laws and Regulations. The issuance and transfer of the Shares will be subject
to and conditioned upon compliance by the Company and Purchaser with all applicable state and U.S. Federal laws and regulations
and with all applicable requirements of any stock exchange or automated quotation system on which the Company’s Common Stock
may be listed or quoted at the time of such issuance or transfer.

 

14.         Interpretation.
Any dispute regarding the interpretation of this Exercise Agreement shall be submitted
by Purchaser or the Company to the Committee for review. The resolution of such a dispute by the Committee shall be final
and binding on the Company and Purchaser.

 

    -9-

     

    

 

15.         Successors
and Assigns. The Company may assign any of its rights under this Exercise Agreement,
including its rights to purchase Shares under the Right of First Refusal. No other party to this Exercise Agreement may
assign, whether voluntarily or by operation of law, any of its rights and obligations under this Exercise Agreement, except with
the prior written consent of the Company. This Exercise Agreement shall be binding upon and inure to the benefit of the
successors and assigns of the Company. Subject to the restrictions on transfer herein set forth, this Exercise Agreement will be
binding upon Purchaser and Purchaser’s heirs, executors, administrators, legal representatives, successors and assigns.

 

16.         Governing
Law. This Exercise Agreement shall be governed by and construed in accordance with
the laws of the State of California as such laws are applied to agreements between California residents entered into and to be
performed entirely within California.

 

17.         Acceptance.
Purchaser hereby acknowledges receipt of a copy of the Plan, the Stock Option Agreement
and this Exercise Agreement. Purchaser has read and understands the terms and provisions thereof, and accepts the Shares
subject to all the terms and conditions of the Plan, the Stock Option Agreement and this Exercise Agreement. Purchaser acknowledges
that there may be adverse tax consequences upon exercise of the Option or disposition of the Shares and agrees that Purchaser shall
consult a tax adviser prior to such exercise or disposition.

 

18.         Notices.
Any notice required to be given or delivered to the Company under the terms of this Exercise
Agreement shall be in writing and addressed to the Corporate Secretary of the Company at its principal corporate offices or to
its facsimile or telecopier number specified below. Any notice required to be given or delivered to Purchaser shall be in
writing and addressed to Purchaser at the address, facsimile or telecopier indicated below or to such other address, facsimile
or telecopier as such party may designate in writing from time to time to the Company. All notices shall be deemed to have
been given or delivered upon: (i) personal delivery; (ii) three (3) days after deposit in the United States mail
by certified or registered mail (return receipt requested); (iii) one (1) business day after deposit with any return
receipt express courier (prepaid); or (iv) one (1) business day after transmission by facsimile or telecopier.

 

19.         Further
Assurances. The parties agree to execute such further documents and instruments and
to take such further actions as may be reasonably necessary to carry out the purposes and intent of this Exercise Agreement.

 

20.         Titles
and Headings. The titles, captions and headings of this Exercise Agreement are included
for ease of reference only and will be disregarded in interpreting or construing this Exercise Agreement. Unless otherwise
specifically stated, all references herein to “sections” and “exhibits” will mean “sections”
and “exhibits” to this Exercise Agreement.

 

21.         Entire
Agreement. The Plan is incorporated herein by reference. The Plan, the Stock
Option Agreement and this Exercise Agreement, together with all Exhibits thereto, constitute the entire agreement and understanding
of the parties with respect to the subject matter of this Exercise Agreement, and supersede all prior understandings and agreements,
whether oral or written, between or among the parties hereto with respect to the specific subject matter hereof.

 

    -10-

     

    

 

22.         Counterparts.
This Exercise Agreement may be executed in any number of counterparts, each of which when
so executed and delivered will be deemed an original, and all of which together shall constitute one and the same agreement.

 

23.         Facsimile
Signatures. This Exercise Agreement may be executed and delivered by facsimile or
electronically in portable document format (.pdf) and upon such delivery the facsimile or portable document format (.pdf) signature
will be deemed to have the same effect as if the original signature had been delivered to the other party.

 

24.         Severability.
If any provision of this Exercise Agreement is determined by any court or arbitrator of
competent jurisdiction to be invalid, illegal or unenforceable in any respect, such provision will be enforced to the maximum extent
possible given the intent of the parties hereto. If such clause or provision cannot be so enforced, such provision shall
be stricken from this Exercise Agreement and the remainder of this Exercise Agreement shall be enforced as if such invalid, illegal
or unenforceable clause or provision had (to the extent not enforceable) never been contained in this Exercise Agreement. Notwithstanding
the foregoing, if the value of this Exercise Agreement based upon the substantial benefit of the bargain for any party is materially
impaired, which determination as made by the presiding court or arbitrator of competent jurisdiction shall be binding, then both
parties agree to substitute such provision(s) through good faith negotiations.

 

[SIGNATURE PAGE FOLLOWS.]

 

    -11-

     

    

 

IN WITNESS WHEREOF,
the Company has caused this Stock Option Exercise Agreement to be executed by its duly authorized representative and Purchaser
has executed this Stock Option Exercise Agreement as of the Effective Date indicated above.

 

	REVIVA PHARMACEUTICALS, INC.:	 	PURCHASER:
	 	 	 
	By:	 	 
	 	 	Signature
	 	 	 
	 	 	 
	(Please print name)	 	(Please print name)
	 	 	 
	(Please print title)	 	 
	 	 	 
	Address:	 	Address:
	 	 	 
	 	 	 
	 	 	 
	Fax No.:	 	Fax No.:
	 	 	 
	Phone No.:	 	Phone No.:

 

List of Exhibits:

 

		Exhibit 1:	Stock Power and Assignment
Separate from Stock Certificate

		Exhibit 2:	Spouse Consent

		Exhibit 3:	Proof of Payment of Exercise
Price and Applicable Tax Obligations

 

[SIGNATURE PAGE TO STOCK OPTION EXERCISE
AGREEMENT]

 

     

     

    

 

EXHIBIT 1

 

STOCK POWER AND ASSIGNMENT

SEPARATE FROM STOCK CERTIFICATE

 

     

     

    

 

Stock Power and Assignment

Separate from Stock Certificate

 

FOR
VALUE RECEIVED and pursuant to that certain Stock Option Exercise Agreement dated as of ______, ____ , (the
 “Agreement”), the undersigned hereby sells, assigns     and
transfers unto_________________ shares of the Common Stock, $0.0001 par value per share, of Reviva
Pharmaceuticals, Inc., a Delaware corporation (the “Company”), standing in the
undersigned’s name on the books of the Company represented by Certificate
No(s)._____     delivered herewith, and does hereby irrevocably
constitute and appoint the Secretary of the Company as the undersigned’s attorney-in-fact, with full power of
substitution, to transfer said stock on the books of the Company. THIS ASSIGNMENT MAY ONLY BE USED AS AUTHORIZED BY
THE AGREEMENT AND ANY EXHIBITS THERETO.

 

	Dated:________________	 
	 	 
	 	PURCHASER:
	 	 
	 	 
	 	(Signature)
	 	 
	 	 
	 	(Please Print Name)
	 	 
	 	 
	 	(Spouse’s Signature, if any)
	 	 
	 	 
	 	(Please Print Spouse’s Name)

 

Instructions to Purchaser: PLEASE
DO NOT FILL IN ANY BLANKS OTHER THAN THE SIGNATURE LINES. The purpose of this Stock Power and Assignment is to enable
the Company to exercise its “Right of First Refusal” set forth in the Agreement without requiring additional signatures
on the part of the Purchaser or Purchaser’s Spouse.

 

     

     

    

 

Stock Power and Assignment Separate
from Stock Certificate

 

FOR
VALUE RECEIVED and pursuant to that certain Stock Option Exercise Agreement dated as of_______, ____, (the
 “Agreement”), the undersigned hereby sells, assigns     and
transfers unto___________________ shares of the Common Stock, $0.0001 par value per share, of Reviva Pharmaceuticals, Inc., a Delaware
corporation (the “Company”), standing in the undersigned’s name on the books of the Company
represented by Certificate No(s)._     delivered
herewith, and does hereby irrevocably constitute and appoint the Secretary of the Company as the undersigned’s
attorney-in-fact, with full power of substitution, to transfer said stock on the books of the Company. THIS ASSIGNMENT
MAY ONLY BE USED AS AUTHORIZED BY THE AGREEMENT AND ANY EXHIBITS THERETO.

 

	Dated:________________	 
	 	 
	 	PURCHASER:
	 	 
	 	 
	 	(Signature)
	 	 
	 	 
	 	(Please Print Name)
	 	 
	 	 
	 	(Spouse’s Signature, if any)
	 	 
	 	 
	 	(Please Print Spouse’s Name)

 

Instructions to Purchaser: PLEASE
DO NOT FILL IN ANY BLANKS OTHER THAN THE SIGNATURE LINES. The purpose of this Stock Power and Assignment is to enable
the Company to exercise its “Right of First Refusal” set forth in the Agreement without requiring additional signatures
on the part of the Purchaser or Purchaser’s Spouse.

 

     

     

    

 

EXHIBIT 2

 

SPOUSE CONSENT

 

     

     

    

 

Spouse Consent

 

The undersigned spouse
of ______________ (the “Purchaser”) has read, understands, and hereby approves the Stock Option Exercise
Agreement between Purchaser and the Company (the “Agreement”). In consideration of the Company’s
granting my spouse the right to purchase the Shares as set forth in the Agreement, the undersigned hereby agrees to be irrevocably
bound by the Agreement and further agrees that any community property interest I may have in the Shares shall similarly be bound
by the Agreement. The undersigned hereby appoints Purchaser as my attorney-in-fact with respect to any amendment or exercise of
any rights under the Agreement.

 

	Dated:________________	 
	 	 
	 	PURCHASER:
	 	 
	 	 
	 	Print Name of Purchaser’s
    Spouse
	 	 
	 	 
	 	Signature of Purchaser’s
    Spouse

 

	 	Address:	
	 	 	 
	 	 	 
	 	 	 
	 	 	 

 

     

     

    

 

EXHIBIT 3

 

PROOF OF PAYMENT OF EXERISE PRICE
AND APPLICABLE TAX

OBLIGATIONSExhibit 10.19

 

NOTE
PURCHASE AGREEMENT

 

This Note Purchase
Agreement (this “Agreement”) is made and entered into as of August 17, 2020, by and among Reviva
Pharmaceuticals, Inc., a Delaware corporation (the “Company”), and the parties identified on the
signature pages hereto (each individually an “Investor” and collectively the “Investors”),
and shall become effective upon the consummation of the SPAC Merger (as defined herein).

 

RECITALS

 

Whereas,
the Company has entered into an Agreement and Plan of Merger, dated as of July 20, 2020 (as it may be amended, the “Merger
Agreement”), among Tenzing Acquisition Corp, a company incorporated in the British Virgin Islands (together with
its successors, the “SPAC Purchaser”), Tenzing Merger Subsidiary Inc., a Delaware corporation and a wholly-owned
subsidiary of the Purchaser (“SPAC Merger Sub”), the Company, and the other parties named therein, pursuant
to which Merger Sub would merge with and into the Company, with the Company continuing as the surviving entity, and the stockholders
of the Company will receive equity securities of SPAC Purchaser (the “SPAC Shares”) in exchange for their
shares of capital stock of the Company (the “SPAC Merger”) in accordance with the terms of the Merger
Agreement; and

 

Whereas,
the Company currently requires funds to help finance its operations prior to the closing of the SPAC Merger; and

 

Whereas,
the Investors are willing to advance funds to the Company, in an aggregate principal amount not to exceed Five Hundred Thousand
Dollars ($500,000.00), for the purpose of financing the Company’s operations in exchange for the issuance to them of certain
convertible promissory notes evidencing the Company’s obligation to repay the Investors’ loans of the advanced funds
as provided in this Agreement.

 

Now,
Therefore, the parties hereby agree as follows:

 

1.            PURCHASE
AND SALE OF NOTES.

 

1.1            Note
Purchase. Subject to the terms and conditions of this Agreement, the Company agrees
to sell to each Investor, and each Investor severally agrees to purchase from the Company, a Convertible Promissory Note, in a
principal amount of not less than Fifty Thousand Dollars ($50,000.00), in the form attached to this Agreement as Exhibit A
(each individually a “Note” and collectively the “Notes”) in the principal
amount set forth on such Investor’s signature page hereto. This Agreement, all of the Notes and any document entered
into, executed or delivered under or in connection with, or for the purpose of amending, any of such documents are collectively
hereinafter referred to as the “Financing Documents.”

 

1.2            [Intentionally
Omitted.]

 

1.3            [Intentionally
Omitted.]

 

    

     

    

 

2.            CLOSING.

 

2.1            The
Closing. The purchase and sale of the Notes will take place at the offices of Lowenstein
Sandler LLP, One Lowenstein Drive, Roseland, New Jersey 07068, at 10:00 a.m. Eastern time, on [●], 2020, or at such
other time and place as the Company and the Investors who have agreed to purchase a majority of the aggregate principal amount
of the Notes mutually agree upon (which time and place are referred to as the “Closing”). At the Closing,
each Investor will deliver to the Company as payment in full for the Note to be purchased by such Investor at the Closing the amount
set forth on such Investor’s signature page hereto by (i) a check payable to the Company’s order, (ii) wire
transfer of funds to the Company or (iii) any combination of the foregoing. At the Closing, the Company will deliver to each
Investor a duly executed Note in the principal amount set forth on such Investor’s signature page hereto.

 

2.2            Additional
Closing(s).

 

(a)            Conditions
of Additional Closing(s). Subject to the terms and conditions of this Agreement, at any time and from time to time after
the Closing the Company may, at one or more additional closings (each an “Additional Closing”), without
obtaining the signature, consent or permission of any of the Investors, offer and sell to other investors (the “New
Investors”), Notes pursuant to this Agreement under terms no more favorable to such New Investors than the terms
and conditions set forth in this Agreement, having an aggregate principal amount of no more than the difference of (i) Five
Hundred Thousand Dollars ($500,000.00) minus (ii) the aggregate principal amount of all Notes previously sold hereunder. New
Investors may include persons or entities who are already Investors under this Agreement.

 

(b)            Additional
Closing Procedures. Each New Investor purchasing one or more Notes at an Additional Closing will execute counterpart signature
pages to this Agreement, and each New Investor will, upon delivery by such New Investor to the Company of such signature pages,
and the payment by such New Investor and the purchase price for the Notes to be acquired by such New Investor to the Company of
the principal amount of the Note(s) become a party to, and bound by, this Agreement to the same extent as if such New Investor
had been an Investor at the Closing. Notwithstanding anything to the contrary contained herein, (i) the representations and
warranties of the Company set forth in Section 3 hereof and the Schedule of Exceptions (as defined below) shall speak only
as of the Closing and the Company shall have no obligation to update the Schedule of Exceptions for any Additional Closing, (ii) the
Company will have no obligation to update any certificates or other documents referred to in Section 5 hereof in connection
with any Additional Closing and (iii)  the representations and warranties of each New Investor participating in an Additional
Closing that are set forth in Section 4 hereof shall speak as of the date of such New Investor’s Additional Closing.

 

(c)            Status
of New Investors. Upon the completion of each Additional Closing as provided in this Section 2, each New Investor
will be deemed to be an “Investor” for all purposes of this Agreement.

 

    2

     

    

 

3.            REPRESENTATIONS
AND WARRANTIES OF THE COMPANY. The Company hereby represents and warrants to
each Investor that, except as set forth in the Schedule of Exceptions (the “Schedule of Exceptions”)
attached to this Agreement as Exhibit B, the statements in the following paragraphs of this Section 3 are all
true and complete as of immediately prior to the Closing:

 

3.1            Organization,
Good Standing and Qualification. The Company has been duly incorporated and organized,
and is validly existing in good standing, under the laws of the State of Delaware. The Company has the corporate power and authority
to own and operate its properties and assets and to carry on its business as currently conducted and as presently proposed to be
conducted.

 

3.2            Due
Authorization. All corporate action on the part of the Company’s board of directors
and stockholders necessary for the authorization, execution, delivery of, and the performance of all obligations of the Company
under, the Financing Documents has been taken or will be taken prior to the Closing. This Agreement constitutes, and the other
Financing Documents that constitute agreements of the Company when executed and delivered by the Company will constitute, valid
and legally binding obligations of the Company, enforceable against the Company in accordance with their respective terms, except
as may be limited by (i) applicable bankruptcy, insolvency, reorganization or other laws of general application relating to
or affecting the enforcement of creditors’ rights generally and (ii) the effect of rules of law governing the availability
of equitable remedies.

 

3.3            Corporate
Power. The Company has the corporate power and authority to execute and deliver the
Financing Documents to which it is a signatory, to issue to the Investors the Notes to be purchased by the Investors hereunder
and to carry out and perform all its obligations under the Financing Documents. No direct or indirect consent, approval, authorization
or similar item is required to be obtained by the Company to enter into the Financing Documents to which it is a party and to perform
or undertake any of the transactions contemplated pursuant to the Financing Documents to which it is a party.

 

3.4            Valid
Issuance.

 

(a)            The
Notes and the Common Stock issuable upon conversion of the Notes, when issued, sold and delivered in accordance with the terms
of this Agreement and the Notes, for the consideration provided for herein and therein, will be duly and validly issued, fully
paid and nonassessable.

 

(b)            Based
in part on the representations made by the Investors in Section 4 hereof, the offer and sale of the Notes solely to the Investors
in accordance with this Agreement (assuming no change in currently applicable law or in the Company’s Certificate of Incorporation
in effect as of immediately prior to the Closing, no transfer of Notes by any Investor and no commission or other remuneration
is paid or given, directly or indirectly, for soliciting the issuance of Common Stock upon conversion of the Notes), and the issuance
of the Common Stock will be exempt from the registration and prospectus delivery requirements of the U.S. Securities Act of 1933,
as amended (the “Securities Act”), and the securities registration and qualification requirements of
the currently effective provisions of the securities laws of the states in which the Investors are resident based upon their addresses
as set forth on their respective signature pages hereto.

 

    3

     

    

 

3.5            Capitalization.
The capitalization of the Company immediately prior to the Closing consists of the following:

 

(a)            Common
Stock. A total of Thirty Five Million (35,000,000) authorized shares of the Company’s Common Stock, par value $0.0001
per share (the “Common Stock”), of which Eighteen Million One Hundred Eighty Thousand Seven Hundred Forty-Eight
(18,180,748) shares are issued and outstanding.

 

(b)            Preferred
Stock. A total of Thirteen Million Six Hundred Twenty Five Thousand Two Hundred Thirty Seven (13,625,237) authorized shares
of Preferred Stock, of which Six Hundred Twenty Five Thousand Two Hundred Thirty-Seven (625,237) shares are designated as Series 1
Preferred Stock, $0.0001 par value per share, all of which are issued and outstanding; One Million Two Hundred Forty-Five Thousand
Eight Hundred Eighty-Nine (1,245,889) shares are designated as Series 2 Preferred Stock, $0.0001 par value per share, all
of which are issued and outstanding; Nine Hundred Fifty-One Thousand Seven Hundred Sixty-One (951,761) shares are designated as
Series 3 Preferred Stock, all of which are issued and outstanding; Five Million (5,000,000) shares are designated as Series 4
Preferred Stock, $0.0001 par value per share, One Million Twenty Nine Thousand Nine Hundred Ninety Four (1,029,994) of which are
issued and outstanding; and Five Million Eight Hundred Two Thousand Three Hundred Fifty (5,802,350) shares are undesignated.

 

(c)            Reserved
Shares. Except for (i) the Three Million (3,000,000) shares of Common Stock reserved for issuance under the Company’s
2006 Equity Incentive Plan (the “Plan”) pursuant to which Four Hundred and Thirty Thousand (430,000)
shares are outstanding; (ii) Thirty Eight Thousand One Hundred and Ninety Nine (38,199) shares of Common Stock issuable upon
the exercise of outstanding warrants; (iii) conversion rights of the Series 1 Preferred Stock, Series 2 Preferred
Stock, Series 3 Preferred Stock, and Series 4 Preferred Stock, (iv) conversion rights in connection the Company’s
outstanding 2016 8% Convertible Promissory Notes with an aggregate principal balance of $3,490,088.00, inclusive of certain note
conversion shares issuable upon a conversion event, (v) conversion and stock issuance rights in connection with the Company’s
outstanding 2018 8% Convertible Promissory Notes with an aggregate principal balance of $275,000.00, inclusive of certain note
conversion shares issuable upon a conversion event, certain warrant issuances upon a conversion event, and the issuance of Eighty
Two Thousand Five Hundred (82,500) shares of Common Stock upon a conversion event, (vi) conversion and stock issuance rights
in connection with the Company’s outstanding 2020 8% Convertible Promissory Notes with an aggregate principal balance of
$610,000.00, inclusive of certain note conversion shares issuable upon a conversion event, certain warrant issuances upon a conversion
event, and the issuance of One Hundred and Ten Thousand (110,000) shares of Common Stock upon a conversion event and (vii) the
rights of first refusal held by the Company to repurchase any shares of its stock that may be issued under the Plan or under that
certain Founder’s Restricted Stock Purchase Agreement by and between the Company and Laxminarayan Bhat dated as of May 2,
2006, there are no outstanding options, warrants, conversion rights, preemptive rights, rights of first refusal or agreements for
the purchase or acquisition of any shares of the Company’s capital stock or any securities convertible into or ultimately
exchangeable or exercisable for any shares of the Company’s capital stock.

 

    4

     

    

 

(d)            The
outstanding shares of the capital stock of the Company are duly authorized and validly issued, fully paid and nonassessable.

 

4.            REPRESENTATIONS,
WARRANTIES AND CERTAIN AGREEMENTS OF INVESTORS. Each Investor hereby, severally
and not jointly, represents and warrants to, and agrees with the Company that:

 

4.1            Authorization.
This Agreement constitutes, and the other Financing Documents that constitute agreements of the Investor when executed and delivered
by the Investor will constitute, such Investor’s valid and legally binding obligations, enforceable against such Investor
in accordance with their terms, except as may be limited by (i) applicable bankruptcy, insolvency, reorganization or other
laws of general application relating to or affecting the enforcement of creditors’ rights generally and (ii) the effect
of rules of law governing the availability of equitable remedies. Each Investor represents and warrants to the Company that
such Investor has full power and authority to enter into this Agreement and acquire such Investor’s Note. There are no actions,
suits, proceedings or investigations pending against such Investor or such Investor's assets before any court or governmental agency
(nor is there any threat thereof) that would impair in any way such Investor's ability to enter into and fully perform its commitments
and obligations under this Agreement or the transactions contemplated hereby.

 

4.2            Purchase
for Own Account. The Notes and Common Stock issuable upon conversion of the Notes
(collectively, the “Securities”) will be acquired for investment for such Investor’s own account,
not as a nominee or agent, and not with a view to the public resale or distribution thereof within the meaning of the Securities
Act, and such Investor has no present intention of selling, granting any participation in, or otherwise distributing the same.

 

4.3            No
Solicitation. At no time was such Investor presented with or solicited by any publicly
issued or circulated newspaper, mail, radio, television or other form of general advertising or solicitation in connection with
the offer, sale and purchase of the Securities.

 

4.4            Reliance
on Exemptions. Such Investor understands that the Securities are being offered and
sold to it in reliance on specific exemptions from the registration requirements of United States federal and state securities
laws and that the Company is relying in part upon the truth and accuracy of, and such Investor’s compliance with, the representations,
warranties, agreements, acknowledgments and understandings of such Investor set forth herein in order to determine the availability
of such exemptions and the eligibility of such Investor to acquire the Securities.

 

4.5            Disclosure
of Information. Such Investor has received or has had full access to all the information
such Investor considers necessary or appropriate to make an informed investment decision with respect to the Securities. Such Investor
further has had an opportunity to ask questions and receive answers from the Company regarding the terms and conditions of the
offering of the Securities and to obtain additional information (to the extent the Company possessed such information or could
acquire it without unreasonable effort or expense) necessary to verify any information furnished to such Investor or to which such
Investor had access. The foregoing, however, does not in any way limit or modify the representations and warranties made by the
Company in Section 3.

 

    5

     

    

 

4.6            Investment
Experience. Such Investor understands that the purchase of the Securities involves
substantial risk. Such Investor (i) has experience as an investor in securities of companies in the development stage and
acknowledges that such Investor is able to fend for itself, can bear the economic risk of such Investor’s investment in the
Securities and has such knowledge and experience in financial or business matters that such Investor is capable of evaluating the
merits and risks of this investment in the Securities and protecting such Investor’s own interests in connection with this
investment in the Securities or (ii) has a preexisting personal or business relationship with the Company and certain of its
officers, directors or controlling persons of a nature and duration that enables such Investor to be aware of the character, business
acumen and financial circumstances of such persons. Such Investor has sought such accounting and legal advice as it has considered
necessary to make an informed investment decision with respect to its acquisition of its Securities. The Investor is relying solely
on their own accounting and legal advisors, and not on any statements of the Company or any of its agents or representatives, for
such accounting and legal advice with respect to its acquisition of the Securities.

 

4.7            No
Governmental Review. Such Investor understands that no United States federal or state
agency or any other government or governmental agency has passed on or made any recommendation or endorsement of the Securities,
or the fairness or suitability of the investment in the Securities, nor have such authorities passed upon or endorsed the merits
of the offering of the Securities.

 

4.8            Organization
and Standing. Such Investor is duly organized, validly existing and in good standing
under the laws of the jurisdiction in which it was formed.

 

4.9            Accredited
Investor Status. Such Investor is an “accredited investor” within the
meaning of Regulation D promulgated under the Securities Act. “Accredited investor” includes, without limitation, (a) a
person or entity who is a director or executive officer of the Company, (b) a natural person whose individual net worth, or
joint net worth with that person’s spouse, at the time of his or her purchase exceeds $1,000,000 after subtracting the value
of such Investor’s primary residence and excluding the related amount of indebtedness secured by the primary resident up
to its fair market value, (c) a natural person who had an individual income in excess of $200,000 in each of the two most
recent years or joint income with that person's spouse in excess of $300,000 in each of those two years and has a reasonable expectation
of reaching the same income level in the current year, (d) a corporation, limited liability company or partnership having
total assets in excess of $5,000,000 that was not formed for the purpose of acquiring the Securities and (e) a trust, with
total assets in excess of $5,000,000, not formed for the specific purpose of acquiring the Securities, whose acquisition is directed
by a person who has such knowledge and experience in financial and business matters that he or she is capable of evaluated the
merits and risks of acquiring the Securities.

 

    6

     

    

 

4.10            Restricted
Securities. Such Investor understands that the Securities are characterized as “restricted
securities” under the Securities Act and Rule 144 promulgated thereunder (“Rule 144”)
since they are being acquired from the Company in a transaction not involving a public offering, and that under the Securities
Act and applicable regulations thereunder the Securities may be resold without registration under the Securities Act only in certain
limited circumstances. Investor further understands that the Company is under no obligation to register the Securities and the
Company has no present plans to do so. Furthermore, such Investor is familiar with Rule 144, as presently in effect, and understands
the limitations imposed thereby and by the Securities Act on resale of the Securities without such registration. Such Investor
understands that, whether or not the Securities may be resold in the future without registration under the Securities Act, no public
market now exists for any of the Securities and that it is uncertain whether a public market will ever exist for the Securities.

 

4.11            Further
Limitations on Disposition. Without in any way limiting the representations set forth
above, such Investor further agrees not to make any disposition of all or any portion of the Securities unless and until:

 

(a)            there
is then in effect a registration statement under the Securities Act covering such proposed disposition and such disposition is
made in accordance with such effective registration statement; or

 

(b)            such
Investor shall have notified the Company of the proposed disposition and shall have furnished the Company with a statement of the
circumstances surrounding the proposed disposition and, at the expense of such Investor or its transferee, with an opinion of counsel
reasonably satisfactory in form and substance to the Company that such disposition will not require registration of such Securities
under the Securities Act.

 

Notwithstanding the provisions of paragraphs
(a) and (b) of this Section 4.11, no such registration statement or opinion of counsel shall be required for any
transfer: (i) of any Securities in compliance with Rule 144 or Rule 144A promulgated under the Securities Act when
the Company is promptly provided evidence of such compliance; (ii) of any Securities by an Investor that is a partnership
or a corporation to (A) a partner of such partnership or stockholder of such corporation, (B) a retired partner of such
partnership who retires after the date hereof, (C) the estate of any deceased partner of such partnership or deceased stockholder
of such corporation; or (iii) by gift, will or intestate succession by any Investor to his or her spouse or lineal descendants
or ancestors or any trust for any of the foregoing; provided that in each of the foregoing cases the transferee agrees in
writing to be subject to the terms of this Agreement and the Notes to the same extent as if the transferee had been an original
Investor hereunder.

 

4.12            Legends.
Such Investor understands and agrees that the certificates evidencing the Securities will bear legends substantially similar to
those set forth below in addition to any other legend that may be required by applicable law, the Company’s Certificate of
Incorporation or Bylaws, Section 4.13 of this Agreement or any other agreement between the Company and such Investor:

 

    7

     

    

 

(a)            THE
SECURITIES REPRESENTED HEREBY HAVE NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED (THE “ACT”),
OR UNDER THE SECURITIES LAWS OF APPLICABLE STATES. THESE SECURITIES ARE SUBJECT TO RESTRICTIONS ON TRANSFERABILITY AND RESALE AND
MAY NOT BE TRANSFERRED OR RESOLD EXCEPT AS PERMITTED UNDER THE ACT AND APPLICABLE STATE SECURITIES LAWS, PURSUANT TO REGISTRATION
UNDER SUCH LAWS OR AN EXEMPTION FROM SUCH REGISTRATION REQUIREMENTS. INVESTORS SHOULD BE AWARE THAT THEY MAY BE REQUIRED TO
BEAR THE FINANCIAL RISKS OF THIS INVESTMENT FOR AN INDEFINITE PERIOD OF TIME. THE ISSUER OF THESE SECURITIES MAY REQUIRE AN
OPINION OF COUNSEL IN FORM AND SUBSTANCE SATISFACTORY TO THE ISSUER TO THE EFFECT THAT ANY PROPOSED TRANSFER OR RESALE IS
IN COMPLIANCE WITH THE ACT AND ALL APPLICABLE STATE SECURITIES LAWS.

 

(b)            Any
legend required by the laws of the State of California, including any legend required by the California Department of Corporations,
or any other state securities laws.

 

The legend set forth in (a) above
shall be removed by the Company from any certificate evidencing the Securities upon delivery to the Company of an opinion of counsel,
reasonably satisfactory in form and substance to the Company, that either (i) a registration statement under the Securities
Act is at that time in effect with respect to the legended security or (ii) such security can be freely transferred in a public
sale (other than pursuant to Rule 144, Rule 144A or Rule 145 promulgated under the Securities Act) without such
a registration statement being in effect and that such transfer will not jeopardize the exemption or exemptions from registration
pursuant to which the Company issued the Securities.

 

4.13            [Intentionally
Omitted.]

 

4.14            Reliance
on Business Plan. Investor understands that the oral and visual components of any
live presentation, executive summary, investment opportunity summary, product development and revenue projections, business model,
investor updates and/or similar documentation previously delivered by the Company and reviewed by Investor were incomplete and
were intended only to give Investor a general idea of the Company’s future intentions. Investor acknowledges that the Company
reserves the right to deviate from the plans set forth in such materials and that the Company is in the early stages of development
and therefore its future plans are highly speculative. Investor acknowledges that any projections contained in the materials delivered
to Investor: (a) were based on various assumptions by management that may have changed or that may prove to be incorrect and
that such assumptions are inherently subject to significant economic and competitive uncertainties and contingencies, many of which
are beyond the control of the Company and its management, and (b) were based upon assumptions with respect to future business
decisions that are subject to change. Investor acknowledges that Investor was encouraged to consult with the management of the
Company at greater length and in more depth concerning the Company’s future business plans and has done so to the extent
desired.

 

4.15            Tax
Liability. Investor has reviewed with its own tax advisors the federal, state, local
and foreign tax consequences of this investment and the transactions contemplated by this Agreement and the Notes. Investor relies
solely on such advisors and not on any statements or representations of the Company, the Company’s counsel, or any of the
Company’s agents. Investor understands that it (and not the Company) shall be responsible for its own tax liability that
may arise as a result of this investment or the transactions contemplated by this Agreement and the Notes.

 

    8

     

    

 

5.            CONDITIONS
TO CLOSING.

 

5.1            Conditions
to Investors’ Obligations. The obligations of each Investor under Section 2
of this Agreement are subject to the fulfillment or waiver, on or before the Closing, of each of the following conditions, the
waiver of which shall not be effective against any Investor who does not consent to such waiver, which consent may be given by
written, oral or telephone communication to the Company or its counsel:

 

(a)            each
of the representations and warranties of the Company contained in Section 3 shall be true and correct in all material respects
on and as of the Closing with the same effect as though such representations and warranties had been made on and as of the date
of the Closing;

 

(b)            the
Company shall have performed and complied with all agreements, obligations and conditions contained in this Agreement that are
required to be performed or complied with by it on or before the Closing and shall have obtained all approvals, consents and qualifications
necessary to complete the purchase and sale described herein; and

 

(c)            the
Company shall have executed and delivered to each Investor a Note, in the form attached hereto as Exhibit A, evidencing
the Company’s indebtedness to such Investor in the amount set forth on such Investor’s signature page hereto.

 

5.2            Condition
to Company’s Obligations. The obligations of the Company to each Investor under
this Agreement are subject to the fulfillment or waiver on or before the Closing or an Additional Closing, as applicable, of each
of the following conditions by such Investor:

 

(a)            Each
of the representations and warranties of such Investor contained in Section 4 shall be true and correct at the Closing (and
with regard to a New Investor at each Additional Closing at which such New Investor acquires Securities under this Agreement) with
the same effect as though such representations and warranties had been made on and as of the Closing or Additional Closing, as
applicable; and

 

(b)            such
Investor shall have performed and complied with all agreements, obligations and conditions contained in this Agreement that are
required to be performed or complied with by it on or before the Closing (and with regard to a New Investor on or before each Additional
Closing at which such New Investor acquires Securities under this Agreement) and shall have obtained all approvals, consents and
qualifications necessary to complete the purchase and sale described herein.

 

    9

     

    

 

6.            REGISTRATION
RIGHTS.

 

6.1            Registration
Rights. The Company agrees that, as promptly as practicable (but in any event within
ninety (90) calendar days after the consummation of the SPAC Merger), the SPAC Purchaser will file with the U.S. Securities and
Exchange Commission (the “SEC”) (at its sole cost and expense) a registration statement registering the
resale of the SPAC Shares issued to the holder of this Note (the “Registration Statement”), and it shall
use its commercially reasonable efforts to have the Registration Statement declared effective as soon as practicable after the
filing thereof. The Company agrees that the SPAC Purchaser will cause such Registration Statement or another registration statement
(which may be a “shelf” registration statement) to remain effective until the earliest of (i) two years from the
issuance of the SPAC Shares, (ii) the date on which Holder ceases to hold the SPAC Shares covered by such Registration Statement
and (iii) the first date on which Holder can sell all of its SPAC Shares under Rule 144 of the Securities Act without
limitation as to the manner of sale or the amount of such securities that may be sold. Holder agrees to disclose its beneficial
ownership, as determined in accordance with Rule 13d-3 of the Securities Exchange Act of 1934, as amended, of the SPAC Shares
to the SPAC Purchaser upon request to assist the SPAC Purchaser in making the determination described above. The SPAC Purchaser’s
obligations to include the SPAC Shares in the Registration Statement are contingent upon Holder furnishing in writing to the SPAC
Purchaser such information regarding Holder, the securities of the SPAC Purchaser held by Holder and the intended method of disposition
of the SPAC Shares as shall be reasonably requested by the SPAC Purchaser to effect the registration of the SPAC Shares, and shall
execute such documents in connection with such registration as the SPAC Purchaser may reasonably request that are customary of
a selling stockholder in similar situations. The SPAC Purchaser may delay filing or suspend the use of any such registration statement
if it determines that in order for the registration statement to not contain a material misstatement or omission, an amendment
thereto would be needed, or if such filing or use could materially affect a bona fide business or financing transaction of the
SPAC Purchaser or would require premature disclosure of information that could materially adversely affect the SPAC Purchaser (each
such circumstance, a “Suspension Event”); provided, that the SPAC Purchaser shall use commercially reasonable
efforts to make such registration statement available for the sale by Holder of such securities as soon as practicable thereafter.
Upon receipt of any written notice from the SPAC Purchaser of the happening of any Suspension Event during the period that the
Registration Statement is effective or if as a result of a Suspension Event the Registration Statement or related prospectus contains
any untrue statement of a material fact or omits to state any material fact required to be stated therein or necessary to make
the statements therein, in light of the circumstances under which they were made (in the case of the prospectus) not misleading,
Holder agrees that it will (i) immediately discontinue offers and sales of the SPAC Shares under the Registration Statement
until Holder receives (A) (x) copies of a supplemental or amended prospectus that corrects the misstatement(s) or
omission(s) referred to above and (y) notice that any post-effective amendment has become effective or (B) notice
from the SPAC Purchaser that it may resume such offers and sales, and (ii) maintain the confidentiality of any information
included in such written notice delivered by the SPAC Purchaser unless otherwise required by applicable law. If so directed by
the SPAC Purchaser, Holder will deliver to the SPAC Purchaser or destroy all copies of the prospectus covering the SPAC Shares
in Holder’s possession; provided, however, that this obligation to deliver or destroy all copies of the prospectus covering
the SPAC Shares shall not apply to (i) the extent that Holder is required to retain a copy of such prospectus (A) in
order to comply with applicable legal, regulatory, self-regulatory or professional requirements or (B) in accordance with
a bona fide pre-existing document retention policy or (ii) copies stored electronically on archival servers as a result of
automatic data back-up.

 

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7.            GENERAL
PROVISIONS.

 

7.1            Survival
of Warranties. The representations, warranties and covenants of the Company and the
Investors contained in or made pursuant to this Agreement shall survive the execution and delivery of this Agreement, the Closing
and each Additional Closing, and shall in no way be affected by any investigation of the subject matter thereof made by or on behalf
of any of the Investors or the Company, as the case may be.

 

7.2            Successors
and Assigns. The terms and conditions of this Agreement shall inure to the benefit
of and be binding upon the respective successors and assigns of the parties, provided, however, that nothing in this
Section 7.2 shall permit any of the Investors to transfer or assign any of the Securities acquired under this Agreement except
as provided in Section 4 and in the Notes.

 

7.3            Governing
Law. This Agreement shall be governed by and construed under the internal laws of
the State of California as applied to agreements among California residents entered into and to be performed entirely within California,
without reference to principles of conflict of laws or choice of laws.

 

7.4            Counterparts;
Facsimile Signatures. This Agreement may be executed in two or more counterparts,
each of which shall be deemed an original, but all of which together shall constitute one and the same instrument. This Agreement
may be executed and delivered by facsimile, or by email in portable document format (.pdf) and delivery of the signature page by
such method will be deemed to have the same effect as if the original signature had been delivered to the other parties hereto.

 

7.5            Headings;
Interpretation. In this Agreement, (i) the meaning of defined terms shall be
equally applicable to both the singular and plural forms of the terms defined; (ii) the captions and headings are used only
for convenience and are not to be considered in construing or interpreting this Agreement and (iii) the words “including,”
 “includes” and “include” shall be deemed to be followed by the words “without limitation”.
All references in this Agreement to sections, paragraphs, exhibits and schedules shall, unless otherwise provided, refer to sections
and paragraphs hereof and exhibits and schedules attached hereto, all of which exhibits and schedules are incorporated herein by
this reference.

 

7.6            Notices.
Unless otherwise provided herein, any notice required or permitted under this Agreement shall be given in writing and shall be
deemed effectively given (i) at the time of personal delivery, if delivered in person; (ii) when sent, if sent by electronic
mail or by facsimile during the recipient’s normal business hours, and if not sent during normal business hours, then on
the next business day; (iii) one (1) business day after deposit with an express overnight courier for United States deliveries,
or three (3) business days after deposit with an express courier for deliveries outside of the United States, in each case
with proof of delivery from the courier requested; or (iv) four (4) business days after deposit in the United States
mail by certified mail (return receipt requested) for United States deliveries when addressed to an Investor at the address set
forth on such Investor’s signature page hereto or, in the case of the Company, at 19925 Stevens Creek Blvd., Suite 100,
Cupertino, California, 95014, or at such other address as any party or the Company may designate for itself to receive notices
by giving ten (10) days’ advance written notice to all required parties in accordance with the provisions of this Section,
with copies to (which shall not constitute notice) Lowenstein Sandler LLP, One Lowenstein Drive, Roseland, New Jersey 07068, Attention:
Steven M. Skolnick, Esq.

 

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7.7            No
Finder’s Fees. Each party represents that it neither is nor will be obligated
for any finder’s or broker’s fee or commission in connection with the transactions contemplated by this Agreement.
Each Investor agrees to indemnify and to hold harmless the Company from any liability for any commission or compensation in the
nature of a finder’s or broker’s fee (and any asserted liability) for which the Investor or any of its directors, officers,
partners, members, employees or representatives is responsible. The Company agrees to indemnify and hold harmless each Investor
from any liability for any commission or compensation in the nature of a finder’s or broker’s fee (and any asserted
liability) for which the Company or any of its officers, employees or representatives is responsible.

 

7.8            Amendments
and Waivers. Any term of this Agreement and the Notes may be amended and the observance
of any term of this Agreement and the Notes may be waived (either generally or in a particular instance and either retroactively
or prospectively), only with the written consent of the Company and the holders of Notes representing at least a majority of the
aggregate Principal Balances (as defined in the Notes) of all the Notes then outstanding (the “Majority Holders”). 
Any amendment or waiver effected in accordance with this Section 7.8 shall be binding upon each holder of Notes then outstanding,
each future holder of such securities, and the Company; provided, however, that New Investors may become parties
to this Agreement in accordance with Section 2.2 without any amendment of this Agreement or any consent or approval of any
Investor; provided, further, that without such Investor’s written consent, no amendment or waiver of any term
of this Agreement shall be effective against an Investor that materially and adversely affects such Investor’s rights hereunder
in a manner that is materially different from and disproportionate to the effect on other Investors. Notwithstanding anything to
the contrary contained herein or in the Notes, from the date of this Agreement until the earlier of (i) the consummation of
the transactions contemplated by the SPAC Merger Agreement or (ii) the termination of the SPAC Merger Agreement in accordance
with its terms, neither this Agreement, nor any of the Notes, may be amended, supplemented or modified, nor may any provision of
this Agreement or the Notes be waived, in each case without the prior written consent of SPAC Purchaser (such consent not to be
unreasonably withheld, delayed or conditioned). SPAC Purchaser is an express intended third party beneficiary of this Section 7.8
and shall have the right to enforce the terms hereof as if it were a direct party hereto.

 

7.9            Severability.
If any provision of this Agreement is determined by any court or arbitrator of competent jurisdiction to be invalid, illegal or
unenforceable in any respect, such provision will be enforced to the maximum extent possible given the intent of the parties hereto.
If such clause or provision cannot be so enforced, such provision shall be stricken from this Agreement and the remainder of this
Agreement shall be enforced as if such invalid, illegal or unenforceable clause or provision had (to the extent not enforceable)
never been contained in this Agreement. Notwithstanding the foregoing, if the value of this Agreement based upon the substantial
benefit of the bargain for any party is materially impaired, which determination as made by the presiding court or arbitrator of
competent jurisdiction shall be binding, then both parties agree to substitute such provision(s) through good faith negotiations.

 

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7.10          Entire
Agreement. This Agreement, together with all exhibits and schedules hereto and the
other Financing Documents, constitute the entire agreement and understanding of the parties with respect to the subject matter
hereof and supersede any and all prior negotiations, correspondence, agreements, understandings, duties or obligations between
the parties with respect to the subject matter hereof.

 

7.11          Further
Assurances. From and after the date of this Agreement, upon the request of any Investor
or the Company, the Company and the Investors shall execute and deliver such instruments, documents or other writings as may be
reasonably necessary or desirable to confirm and carry out and to effectuate fully the intent and purposes of this Agreement.

 

[Signature
Pages Follow]

 

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IN WITNESS WHEREOF,
the undersigned has executed this Note Purchase Agreement effective as of the date first written above.

 

	
        REVIVA PHARMACEUTICALS, INC.:

         

	
        

        Signature:
	 	 	 
	 	 	 	 
	Name:	Laxminarayan Bhat, Ph.D.	 	 
	 	 	 	 
	Title:	President and Chief Executive Officer	 
	 	 	 
	Phone:	(408) 960.2209	 	 
	 	 	 	 
	Fax:	(408) 904.6270	 	 
	 	 	 	 
	E-mail:	LBhat@Revivapharma.com	 	 

 

Attachments:

 

	Exhibit A	–	Form of Note
	Exhibit B	–	Schedule of Exceptions

 

[Signature
Page to Reviva Note Purchase Agreement (2020 Working Capital)]

 

    

     

    

 

IN WITNESS WHEREOF,
the undersigned has executed this Note Purchase Agreement effective as of the date first written above.

 

	 	 	INVESTOR: 
	 	 	 
	 	Signature:	 
	 	 	 
	 	Print Name:	 
	 	 	 
	 	Signature	 
	 	 	 
	 	Print Name	 
	 	 	 
	 	Title (if applicable):	 
	 	 	 
	 	Dollar Amount Invested (Notes):	 
	 	 	 
	 	Address:	 
	 	 	 
	 	Phone No:	 
	 	 	 
	 	Fax No.:	 
	 	 	 
	 	E-mail:	 
	 	 	 
	 	Date of Investment: 	 
	 	 	 	 

 

Attachments:

 

	Exhibit A	–	Form of
Note
	Exhibit B	–	Schedule
of Exceptions

 

[Signature
Page to Reviva Note Purchase Agreement (2020 Working Capital)]

 

    

     

    

 

EXHIBIT A

 

FORM OF
NOTE

 

    

     

    

 

EXHIBIT B

 

SCHEDULE OF EXCEPTIONS

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