EXHIBIT 10.1

EXCHANGE AGREEMENT

THIS EXCHANGE AGREEMENT (this “Agreement”) is dated as of September 16, 2010, by
and between Arrowhead Research Corporation, a Delaware corporation (the
“Corporation”), and                      (the “Holder”). The Corporation and the
Holder are referred to as a “Party” and collectively as the “Parties”.

W I T N E S S E T H:

WHEREAS, the Corporation and the Holder are shareholders of Calando
Pharmaceuticals, Inc., a Delaware corporation (“Calando”);

WHEREAS, the Holder owns      shares of Series A Preferred Stock, $0.0001 par
value per share, (the “Calando Shares”);

WHEREAS, for strategic reasons, the Corporation wishes to acquire the Calando
Shares;

WHEREAS, the Holder desires to exchange all the Calando Shares for a warrant,
with an exercise price of $0.50, to purchase      shares of common stock of the
Corporation, $0.0001 par value per share (the “Arrowhead Warrant”); and

NOW, THEREFORE, for good and valuable consideration, the receipt and sufficiency
of which are hereby acknowledged, the parties hereto agree as follows:

1. Exchange.

(a) Exchange Ratio. The Corporation and the Holder hereby agree to exchange at
the Closing the Calando Shares for Arrowhead Warrant, the form of which is
attached hereto as Exhibit A.

(b) Exchange. To effect this exchange, the Holder will deliver to the
Corporation the stock certificate or certificates representing the Calando
Shares together with duly executed stock powers related thereto and the
Corporation will deliver to the Holder the Arrowhead Warrant.

2. The Closing.

(a) Closing Date. The closing of the transactions contemplated by this Agreement
(the “Closing”) shall take place at the offices of Arrowhead Research
Corporation, 201 South Lake Street, Suite 703, Pasadena, CA 91101 at 10:00 a.m.,
Pacific time, on September 16, 2010 (“Closing Date”), or at such other place,
date or time as the parties may mutually agree in writing.

(b) Conditions to Closing of Holder. The obligation of the Holder to consummate
the transactions on the Closing Date as contemplated by this Agreement shall be
subject to the satisfaction or waiver on or prior to the Closing Date of the
following conditions:

(i) the Corporation shall have performed and complied in all material respects
with all obligations and agreements required to be performed and complied with
by the Corporation hereunder on or prior to the Closing Date;

 

1

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

(ii) the representations and warranties of the Corporation contained in this
Agreement shall be true and correct in all material respects as of the Closing
Date as if made as of such date;

(iii) the Corporation shall have received all third party consents and all
authorizations, consents and approvals of any Governmental Authority necessary
to consummate the transactions contemplated hereby.

(c) Conditions to Closing of Corporation. The obligation of the Corporation to
consummate the transactions on the Closing Date shall be subject to the
satisfaction or waiver on or prior to the Closing Date of the following
conditions:

(i) The Holder shall have performed and complied in all material respects with
all obligations and agreements required to be performed and complied with by the
Holder hereunder on or prior to the Closing Date;

(ii) the representations and warranties of the Holder contained in this
Agreement shall be true and correct in all material respects as of the Closing
Date as if made as of such date;

(iii) The Holder shall have delivered to the Corporation a certificate or the
certificates representing all the Calando Shares to be exchanged on such date
and related executed stock powers;

(iv) The Corporation shall have received approval of NASDAQ for the Listing of
Additional Shares relating to the shares underlying the Arrowhead Warrant; and

(v) The Holder shall have received all third party consents and all
authorizations, consents and approvals of any Governmental Authority necessary
to consummate the transactions contemplated hereby.

3. Representations and Warranties of the Corporation. The Corporation represents
and warrants to Holder as follows:

(a) Corporate Status. The Corporation is a corporation incorporated, validly
existing and in good standing under the laws of the State of Delaware with full
right, power and authority to execute, deliver and perform this Agreement.

(b) Authorization/Enforceability. This Agreement has been duly authorized,
executed and delivered by the Corporation and constitutes the valid and legally
binding obligation of the Corporation, enforceable in accordance with its terms
and conditions. The Corporation need not give any notice to, make any filing
with, or obtain any authorization, consent, or approval of any Governmental
Authority in order to consummate the transactions contemplated by this
Agreement.

 

2

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

(c) Non-Contravention. Neither the execution and the delivery of this Agreement,
nor the consummation of the transactions contemplated hereby, will (i) violate
any constitution, statute, regulation, rule, injunction, judgment, order,
decree, ruling, charge, or other restriction of any Governmental Authority to
which the Corporation is subject, or (ii) conflict with, result in a breach of,
constitute a default under, result in the acceleration of, create in any party
the right to accelerate, terminate, modify, or cancel, or require any notice
under the certificate of incorporation or bylaws of the Corporation, or any
agreement, contract, lease, license, instrument, or other arrangement to which
the Corporation is a party or by which it is bound or to which any of its assets
is subject.

(d) Consents/Approvals. No consent, approval, authorization, order, registration
or qualification of or with any Governmental Authority or other Person or entity
is required for the issuance and sale of the Arrowhead by the Corporation to
Holder or the consummation by the Corporation of the transactions contemplated
by this Agreement, provided, however, that the Corporation may be required to
file a Notification of Listing of Additional Shares with NASDAQ with respect to
the transactions contemplated herein.

(e) Arrowhead Warrant Authorization. The Arrowhead Warrant has been duly
authorized and, when the underlying shares are issued and delivered upon due
exercise thereof, the underlying shares of Arrowhead common stock will be duly
and validly issued and fully paid and non-assessable. Upon consummation of the
transactions contemplated hereby, good and valid title to the Arrowhead Warrant,
free and clear of all Claims, will be transferred by the Corporation to Holder.

4. Representations and Warranties of Holder. The Holder represents and warrants
to the Corporation as follows:

(a) Legal Capacity. The Holder has full legal right, power and capacity to
execute and deliver this Agreement and to perform his obligations hereunder.
This Agreement constitutes the valid and legally binding obligation of Holder,
enforceable in accordance with its terms and conditions. Holder need not give
any notice to, make any filing with, or obtain any authorization, consent, or
approval of any third party or Governmental Authority in order to consummate the
transactions contemplated by this Agreement.

(b) Title to Calando Shares. Holder is the lawful record and beneficial owner of
the Calando Shares that will be transferred pursuant to Section 1 of this
Agreement with good and marketable title thereto, and the Holder has the right
to sell, assign, convey, transfer and deliver the Calando Shares and any and all
rights and benefits incident to the ownership thereof (including, without
limitation, any registration or other rights pertaining to the Calando Shares),
all of which rights and benefits are transferable by the Holder to the
Corporation pursuant to this Agreement, free and clear of all Claims. The
exchange of the securities as contemplated herein will (i) pass good and
marketable title to all the Calando Shares transferred pursuant to Section 1 of
this Agreement to the Corporation, free and clear of all Claims, and
(ii) convey, free and clear of all Claims, any and all rights and benefits
incident to the ownership of such securities (including, without limitation, any
registration or other rights pertaining to the securities and the shares of
common stock underlying such securities).

 

3

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

(c) Non-Contravention. Neither the execution and the delivery of this Agreement,
nor the consummation of the transactions contemplated hereby, will (i) violate
any constitution, statute, regulation, rule, injunction, judgment, order,
decree, ruling, charge, or other restriction of any Governmental Authority to
which Holder is subject, or (ii) conflict with, result in a breach of,
constitute a default under, result in the acceleration of, create in any party
the right to accelerate, terminate, modify, or cancel, or require any notice
under any agreement, organizational document, bylaws, partnership agreement,
trust agreement, agreement any trust is bound by, contract, lease, license,
instrument, or other arrangement to which Holder, as applicable, is a party or
by which it is bound or to which any of its assets is subject.

(d) Consents/Approvals. No consent, approval, authorization, order, registration
or qualification of or with any Governmental Authority or other entity or Person
is required for the Exchange or the consummation by Holder of the transactions
contemplated by this Agreement.

(e) Investment Representations.

(i) Holder qualifies as an “accredited investor” (as defined in Rule 501(a) of
Regulation D under the Securities Act of 1933, as amended (the “Securities
Act”)) and is acquiring the Arrowhead Warrant and the shares underlying the
Arrowhead Warrant hereunder for its own account and with no intention of
distributing or selling the Arrowhead Warrant or the shares underlying the
Arrowhead Warrant except pursuant to a registration or an available exemption
under applicable law. Holder understands that neither Arrowhead Warrant or the
shares of common stock underlying the Arrowhead Warrant have not been (and are
not being) registered under the Securities Act by reason of their contemplated
issuance in transaction(s) exempt from the registration and prospectus delivery
requirements of the Securities Act pursuant to Section 4(2) thereof (including
the rules and regulations promulgated thereunder), and that the reliance of the
Corporation on such exemption from registration is predicated in part on the
representations and warranties of Holder hereunder.

(ii) Holder agrees that it will not sell or otherwise dispose of the Arrowhead
Warrant or any of the shares underlying the Arrowhead Warrant unless such sale
or other disposition has been registered or is exempt from registration under
the Securities Act and has been registered or qualified or is exempt from
registration or qualification under applicable securities laws of any State.

(iii) Holder understands that a restrictive legend consistent with the foregoing
set forth in Section 10(a) of this Agreement has been or will be placed on the
Arrowhead Warrant and any certificates evidencing the shares underlying the
Arrowhead Warrant to be issued to it hereunder, and related stop transfer
instructions will be noted in the transfer records of the Corporation and/or its
transfer agent during the Prohibited Period.

 

4

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

(iv) Holder represents that it is not an Affiliate (as defined herein) of the
Corporation and will covenant and agree that if it becomes an Affiliate, it will
promptly provide notice to the Corporation of such status and comply with
insider trading laws and policies and the applicable “control securities”
provisions of Rule 144 in addition to any other obligations set forth in this
Agreement.

(v) Holder has such knowledge and experience in financial and business matters
so as to be capable of evaluating the merits and risk of an investment in the
Arrowhead Warrant and the shares underlying the Arrowhead Warrant. Holder
acknowledges that it has had access to all information concerning the
Corporation and Calando and their respective businesses, assets, liabilities,
financial statements, and obligations which have been requested and has been
provided the opportunity to ask questions of and receive answers from the
Corporation and/or Calando to fully and effectively evaluate the Exchange and
the transactions contemplated herein. Holder understands that a new holding
period for purposes of Rule 144 under the Securities Act will be triggered with
respect to the Arrowhead Warrant and the shares underlying the Warrant, and such
Holder is able to bear the economic risk of loss of the investment in such
securities and is able to afford a complete loss of such investment.

5. Indemnification.

(a) The Holder understands and acknowledges that the Corporation is relying on
representations, warranties, covenants and agreements made by such Holder to the
Corporation in this Agreement. The Holder, as applicable, hereby agrees to
indemnify, defend and hold harmless the Corporation, its Affiliates and their
directors, officers, shareholders, principals, representatives, agents and
employees (each, a “Corporation Indemnified Party”), against any and all loss,
damage, liability or expense (including, but not limited to, expenses related to
the investigation and enforcement of any provisions of this Agreement and/or any
reasonable attorneys’ fees) (collectively, “Losses”) which any Corporation
Indemnified Party may suffer, sustain or incur by reason of or in connection
with or arising under (i) any inaccuracy or breach of representation or warranty
of the Holder contained in this Agreement; (ii) the breach of this Agreement or
any covenant or agreement made by such Holder in this Agreement; or (iii) the
sale or distribution by such Holder of the Arrowhead Warrant or the underlying
shares of common stock in violation of this Agreement and/or the Securities Act
or any other applicable law. This right to indemnification is in addition to any
other remedy available to the Corporation under this Agreement.

(b) The Corporation understands and acknowledges that the Holder is relying on
representations, warranties, covenants and agreements made by the Corporation to
the Holder in this Agreement. The Corporation hereby agrees to indemnify, defend
and hold harmless the Holder and its officers, principals, Affiliates, trustees,
agents and representatives, as applicable, (each, a “Holder Indemnified Party”),
against any and all Losses which any Holder Indemnified Party may suffer,
sustain or incur by reason of or in connection with or arising under (i) any
inaccuracy or breach of representation or warranty of the Corporation contained
in this Agreement; or (ii) the breach of this Agreement or any covenant or
agreement made by the Corporation in this Agreement. This right to
indemnification is in addition to any other remedy available to the Holder under
this Agreement.

 

5

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

6. Certain Definitions.

(a) “Affiliate” (and, with a correlative meaning, “affiliated”) means, with
respect to any Person, any direct or indirect subsidiary of such Person, and any
other Person that directly, or through one or more intermediaries, Controls or
is Controlled by or is under common Control with such first Person. As used in
this definition, “Control” (and, with correlative meanings, “Controlled by” and
“under common Control with”) means the possession, directly or indirectly, of
the power to direct the management or policies of a Person (whether through
ownership of securities or partnership or other ownership interests, by contract
or otherwise).

(b) “Claims” shall mean the following of any nature whatsoever: security
interests, liens, deeds of trust, hypothecations, pledges, claims (pending or
threatened), charges, escrows, encumbrances, lock-up arrangements, options,
rights of first offer or refusal, community property rights, mortgages,
indentures, security agreements or other agreements, arrangements, contracts,
commitments, understandings or obligations, whether written or oral and whether
or not relating in any way to credit or the borrowing of money.

(c) “Governmental Authority” means any entity exercising executive, legislative,
judicial, regulatory or administrative functions of or pertaining to government,
including any governmental authority, independent or autonomous official
authority, agency, department, board, commission or instrumentality of the
United States or any other country, or any political subdivision thereof,
whether federal, state or local, and any tribunal, court or arbitrator(s) of
competent jurisdiction.

(d) “Person(s)” means and includes any natural persons, sole proprietorships,
corporations, limited partnerships, limited liability companies, general
partnerships, joint stock companies, joint ventures, associations, companies,
trusts, banks, trust companies, land trusts, business trusts or other
organizations, whether or not legal entities, all Governmental Authorities and
all other entities.

7. Miscellaneous.

(a) Legend Requirement. The Arrowhead Warrant and each certificate representing
shares issued pursuant to the warrant held or acquired by the Holder will
contain legends acknowledging that the shares represented by such certificate
are restricted securities and are subject to this Agreement, as follows:

THE SECURITIES REPRESENTED BY THIS INSTRUMENT HAVE NOT BEEN REGISTERED UNDER THE
SECURITIES ACT OF 1933, AS AMENDED (THE “SECURITIES ACT”), OR ANY STATE
SECURITIES LAWS, AND NO SALE, ASSIGNMENT, PLEDGE, HYPOTHECATION, GIFT, TRANSFER
OR OTHER DISPOSITION OR OFFER TO DO ANY OF THE FOREGOING MAY BE MADE UNLESS A
REGISTRATION STATEMENT UNDER THE SECURITIES ACT AND OTHER APPLICABLE SECURITIES
LAWS WITH RESPECT TO SUCH SECURITIES IS THEN IN EFFECT, OR IN THE OPINION OF
COUNSEL ACCEPTABLE TO THE ISSUER, SUCH REGISTRATION UNDER THE SECURITIES ACT AND
OTHER APPLICABLE SECURITIES LAWS IS NOT REQUIRED.

 

6

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

The Transfer Agent and any applicable broker shall each be instructed not to
recognize any transfer by a Holder that does not comply with this Agreement.

(b) Equitable Remedy. Each Party shall agree that in addition to any other
remedy that may be available to such Party hereunder, the Party shall be
entitled to specific performance. Notwithstanding anything to the contrary in
this Agreement, each Party shall be responsible for paying its own expenses,
including legal fees, incurred in enforcing this Agreement.

(c) Notices. All notices, claims, demands and other communications hereunder
shall be in writing and shall be deemed given upon (i) confirmation of receipt
of a facsimile transmission, (ii) confirmation of delivery when delivered by a
standard overnight carrier or (iii) the expiration of five (5) business days
after the day when mailed by registered or certified mail (postage prepaid,
return receipt requested), addressed to the respective Parties at the following
addresses (or such other address for a Party as shall be specified by like
notice):

 

If to the Corporation, to:    Arrowhead Research Corporation       201 South
Lake Avenue, Suite 703       Pasadena, CA 91101       Attention: Dr. Christopher
Anzalone       Telephone: (626) 304-3400       Fax: (626) 304-3401    If to the
Holder, to:      

(d) No Third-Party Beneficiaries. Unless otherwise specifically set forth
herein, this Agreement shall not confer any rights or remedies upon any Person
other than the Parties hereto and their respective successors and assigns.

(e) Entire Agreement. This Agreement (including the documents referred to
herein) constitutes the entire agreement among the parties hereto and supersedes
any prior understandings, agreements, or representations by or among the
parties, written or oral, to the extent they relate in any way to the subject
matter hereof.

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

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

 

7

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

(h) Governing Law. This Agreement shall be governed by and construed in
accordance with the domestic laws of the State of Delaware without giving effect
to any choice or conflict of law provision or rule (whether of the State of
Delaware or any other jurisdiction) that would cause the application of the laws
of any jurisdiction other than the State of Delaware.

(i) Amendments and Waivers. No amendment of any provision of this Agreement
shall be valid unless the same shall be in writing and signed by the Corporation
and the Holder.

(j) Gender. All pronouns and any variation thereof shall be deemed to refer to
the masculine, feminine, neuter, singular, or plural as the identity of the
person or entity or the context may require.

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

(l) No Presumption Against Drafter. Each of the Parties has jointly participated
in the negotiation and drafting of this Agreement. In the event of any ambiguity
or a question of intent or interpretation arises, this Agreement shall be
construed as if drafted jointly by each of the Parties and no presumptions or
burdens of proof shall arise favoring any Party by virtue of the authorship of
any of the provisions of this Agreement.

(m) Successors and Assigns. Except as otherwise specifically provided herein,
this Agreement shall be binding upon, and inure to the benefit of, the Parties
hereto and their respective successors and permitted assigns.

(n) Survival. All covenants, agreements, representations and warranties made
herein shall survive the Closing and the consummation of the Exchange of the
Calando Shares.

 

8

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

IN WITNESS WHEREOF, this Exchange Agreement has been duly executed by or on
behalf of each of the parties hereto on the date first above written.

 

ARROWHEAD RESEARCH CORPORATION, a Delaware corporation By:  

 

      Name:       Title:

 

HOLDER:

 

 

 

9

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

EXHIBIT A

FORM OF WARRANT AGREEMENT