EX-4.3 Form of Common Stock Purchase Warrant



 NEITHER THESE SECURITIES NOR THE SECURITIES FOR WHICH THESE SECURITIES ARE EXERCISABLE HAVE BEEN
REGISTERED WITH THE SECURITIES AND EXCHANGE COMMISSION OR THE SECURITIES COMMISSION OF ANY STATE IN RELIANCE UPON AN EXEMPTION FROM REGISTRATION UNDER THE SECURITIES ACT OF 1933, AS AMENDED (THE “SECURITIES ACT”), AND, ACCORDINGLY, MAY NOT
BE OFFERED OR SOLD EXCEPT PURSUANT TO AN EFFECTIVE REGISTRATION STATEMENT UNDER THE SECURITIES ACT OR PURSUANT TO AN AVAILABLE EXEMPTION FROM, OR IN A TRANSACTION NOT SUBJECT TO, THE REGISTRATION REQUIREMENTS OF THE SECURITIES ACT AND IN ACCORDANCE
WITH APPLICABLE STATE SECURITIES LAWS. 
 RXI PHARMACEUTICALS CORPORATION 

WARRANT 
  

			
	Warrant No. 2011-1	  	Effective Date: February 1, 2011

 RXi Pharmaceuticals Corporation, a Delaware corporation (the “Company”), hereby
certifies that, for value received, Legend Securities, Inc., or its registered Permitted Transferees (together, the “Holder”), as registered owner of this warrant (the “Warrant”), is entitled to
purchase from the Company up to a total of 150,000 shares (as adjusted from time to time as provided in Section 10) of Common Stock, at an exercise price equal to $2.10 per share (as adjusted from time to time as provided in
Section 10, the “Exercise Price”), upon such shares becoming Vested Shares, at any time and from time to time from and after the date of this Warrant (the “Initial Exercise Date”) to and
including February 1, 2016 (the “Expiration Date” and the period starting with the Initial Exercise Date and ending on the Expiration Date is referred to as the “Term”), and subject to the
following terms and conditions: 
 1. Definitions. The capitalized terms used herein and not otherwise defined shall have
the meanings set forth below: 
 “Affiliate” of any specified Person means any other person or entity
directly or indirectly controlling, controlled by or under direct or indirect common control with such specified Person. For purposes of this definition, “control” means the power to direct the management and policies of such
Person or firm, directly or indirectly, whether through the ownership of voting securities, by contract or otherwise. 

“Commission” means the United States Securities and Exchange Commission. 

“Common Stock” means the common stock of the Company, $0.0001 par value per share. 

“Eligible Market” means any of the New York Stock Exchange, the American Stock Exchange or Nasdaq (as defined
below), and any successor markets thereto. 







 “Exchange Act” means the Securities Exchange Act of 1934, as
amended 
 “Market Price” shall mean (i) if the principal trading market for such securities is an
exchange, the average of the last reported sale prices per share for the last ten previous Trading Days in which a sale was reported, as officially reported on any consolidated tape or (ii) if clause (i) is not applicable, the average of
the closing bid price per share for the last ten previous Trading Days as set forth in the National Quotation Bureau sheet listing for such securities. Notwithstanding the foregoing, if there is no reported sales price or closing bid price, as the
case may be, on any of the ten Trading Days preceding the event requiring a determination of Market Price hereunder, then the Market Price shall be determined in good faith after reasonable investigation by resolution of the Board of Directors of
the Company. 
 “Nasdaq” means the Nasdaq Global Market or Nasdaq Capital Market, and any successor
markets thereto. 
 “Permitted Transferees” means only Persons who are the directors, officers and
employees of the Holder. 
 “Person” means any court or other federal, state, local or other
governmental authority or other individual or corporation, partnership, trust, incorporated or unincorporated association, joint venture, limited liability company, joint stock company, government (or an agency or subdivision thereof) or other
entity of any kind. 
 “Trading Day” means (a) any day on which the Common Stock is listed or
quoted and traded on any Eligible Market or (b) if the Common Stock is not then quoted and traded on any Eligible Market, then a day on which trading occurs on the Nasdaq Global Market (or any successor thereto). 

“Vested Shares” means Warrant Shares that have become vested as described in and pursuant to
Section 4 hereunder. 
 “Warrant Shares” shall initially mean shares of Common Stock and in
addition may include Other Securities and Substituted Property (as defined in Section 10(e)(x)) issued or issuable from time to time upon exercise of this Warrant. 
 2. Registration of Warrant. The Company shall register this Warrant, upon records to be maintained by the Company for that purpose (the “Warrant Register”), in the name of
the record Holder hereof from time to time. The Company may deem and treat the registered Holder of this Warrant as the absolute owner hereof for the purpose of any exercise hereof or any distribution to the Holder, and for all other purposes.








 3. Registration of Transfers. The Company shall register the transfer of any portion
of this Warrant in the Warrant Register, which transfer shall only be made to a Permitted Transferee and in accordance with applicable securities laws, upon surrender of this Warrant, with the Form of Assignment attached hereto as
Appendix A duly completed and signed, to the Company at its address specified herein. Upon any such registration and transfer, a new warrant in substantially the form of a Warrant (any such new warrant, a “New
Warrant”), evidencing the portion of this Warrant so transferred shall be issued to the Permitted Transferee and a New Warrant evidencing the remaining portion of this Warrant not so transferred, if any, shall be issued to the
transferring Holder. The acceptance of the New Warrant by the Permitted Transferee thereof shall be deemed the acceptance by such Permitted Transferee of all of the rights and obligations of a holder of a Warrant. 

4. Vesting of Warrant Shares. The Warrant Shares issued hereunder shall vest completely and in favor of Legend in the following
installments (the “Installments”) as described in this Section 4. The first Installment in the amount of 37,500 shares shall vest on the Effective Date of the Investment Banking Agreement, and the three remaining
Installments, each in the amount of 37,500 shares, shall vest on each quarterly anniversary of the Effective Date of the Investment Banking Agreement following unless the letter agreement between Legend Securities and the Company dated
February 1, 2011 has been terminated prior to each such date. 
 5. Exercise and Duration of Warrant. 

(a) The Vested Shares under this Warrant shall be exercisable, either in its entirety or for a portion of the number of Vested Shares, by
the registered Holder at any time and from time to time from and after the Initial Exercise Date to and including the Expiration Date. At 5:00 P.M. Boston, Massachusetts time on the Expiration Date, the portion of this Warrant not exercised
prior thereto shall be and become void and of no value, and the Holder hereof shall have no right to purchase any additional Warrant Shares hereunder. 
 (b) A Holder may exercise this Warrant by delivering to the Company, in accordance with Section 13, this Warrant, together with (i) an exercise notice, in the form attached hereto as
Appendix B (the “Exercise Notice”), appropriately completed and duly signed, and (ii) (A) payment of the Exercise Price for the number of Warrant Shares as to which this Warrant is being exercised
pursuant to a Cash Exercise (as set forth in Section 5(c) below) or (B) if available pursuant to Section 5(d) below, by notifying the Company that this Warrant is being exercised pursuant to a Cashless Exercise (as set
forth in Section 5(d) below), and the date such items are received by the Company is an “Exercise Date.” Execution and delivery of an Exercise Notice in respect of less than all of the Warrant Shares issuable upon
exercise of this Warrant shall result in the cancellation of the original Warrant and issuance of a New Warrant evidencing the right to purchase the remaining number of Warrant Shares. 

(c) Cash Exercise. In the event the Holder has elected to pay the Exercise Price in cash, it shall pay the Exercise Price by
certified bank check payable to the order of the Company or by wire transfer of immediately available funds in accordance with the Company’s instructions (a “Cash Exercise”). 







 (d) Cashless Exercise. Notwithstanding anything contained herein to the contrary, the
Holder may, in its sole discretion, exercise this Warrant in whole or in part and, in lieu of making the cash payment otherwise contemplated to be made to the Company upon such exercise in payment of the Exercise Price, elect instead to receive upon
such exercise the “Net Number” of shares of Common Stock determined according to the following formula (a “Cashless Exercise”): 
  

					
	Net Number =	 	
(A * B) – (A * C)
	 	
	 	B	 	

 For purposes of the foregoing formula, 
 A = the total number of shares with respect to which this Warrant is then being exercised. 
 B = the closing price per share of the Common Stock (as reported by Bloomberg) on the Trading Day immediately preceding the date of the Exercise Notice. 

C = the Exercise Price then in effect for the applicable Warrant Shares at the time of such exercise. 

(e) Except as otherwise provided for herein, this Warrant shall not entitle the Holder to any voting rights or other rights as a
stockholder of the Company by virtue of the ownership hereof. 
 6. Delivery of Warrant Shares. 

(a) Upon exercise of this Warrant, the Company shall promptly issue or cause to be issued and deliver or cause to be delivered to the
Holder, in such name or names as the Holder may designate, a certificate for the Warrant Shares issuable upon such exercise (the “Certificate”) bearing no restrictive legends. The Holder, or any Person so designated by the
Holder to receive the Warrant Shares, shall be deemed to have become holder of record of such Warrant Shares as of the Exercise Date. 
 (b) Neither these securities nor the securities for which these securities are exercisable have been registered with the Commission or the securities commission of any state in reliance upon an exemption
from registration under the Securities Act of 1933 (the “Securities Act”), and, accordingly, may not be offered or sold except pursuant to an effective registration statement under the Securities Act or pursuant to an
available exemption from, or in a transaction not subject to, the registration requirements of the Securities Act and in accordance with applicable state securities laws. The Holder acknowledges and agrees that the Warrant may be sold only pursuant
to an applicable exemption from the registration requirements of the Securities Act and that the Warrant Shares may only be sold pursuant to an effective registration statement under the Securities Act or in accordance with any applicable exemption
from the registration requirements of the Securities Act. 







 (c) This Warrant is exercisable, either in its entirety or, from time to time, for a portion
of the number of Warrant Shares. Upon surrender of this Warrant following one or more partial exercises, the Company shall issue or cause to be issued, at its expense, a New Warrant evidencing the right to purchase the remaining number of Warrant
Shares. 
 7. Charges, Taxes and Expenses. Issuance and delivery of certificates for shares of Common Stock upon exercise
of this Warrant shall be made without charge to the Holder for any issue or transfer tax, transfer agent fee or other incidental tax or expense in respect of the issuance of such certificates, all of which taxes and expenses shall be paid by the
Company; provided, however, that the Company shall not be required to pay any tax which may be payable in respect of any transfer involved in the issue, delivery or registration of any certificates for Warrant Shares or Warrant in a
name other than that of the Holder and that the Holder will be required to pay any tax with respect to cash received in lieu of fractional shares. The Holder shall be responsible for all other tax liability that may arise as a result of holding or
transferring this Warrant or receiving Warrant Shares upon exercise hereof. 
 8. Replacement of Warrant. If this Warrant
is mutilated, lost, stolen or destroyed, the Company, at the sole expense of the Holder (such expenses, if any imposed by the Company to be reasonable), shall issue or cause to be issued in exchange and substitution for and upon cancellation hereof,
or in lieu of and in substitution for this Warrant, a New Warrant, but only upon receipt of evidence reasonably satisfactory to the Company of such loss, theft or destruction and customary and reasonable indemnity, if requested by the Company.

 9. Reservation of Warrant Shares. The Company covenants that it will at all times reserve and keep available out of
the aggregate of its authorized but unissued and otherwise unreserved Common Stock, solely for the purpose of enabling it to issue Warrant Shares upon exercise of this Warrant as herein provided, the number of Warrant Shares which are then issuable
and deliverable upon the exercise of this entire Warrant, free from all taxes, liens, claims, encumbrances with respect to the issuance of such Warrant Shares and will not be subject to any pre-emptive rights or similar rights (taking into account
the adjustments and restrictions of Section 10 hereof). The Company covenants that all Warrant Shares so issuable and deliverable shall, upon issuance and the payment of the applicable Exercise Price in accordance with the terms hereof,
be duly and validly authorized, issued, fully paid and nonassessable. The Company will take all such action as may be necessary to assure that such shares of Common Stock may be issued as provided herein without violation of any applicable law or
regulation, or of any requirements of any securities exchange or automated quotation system upon which the Common Stock may be listed or quoted, as the case may be; provided, however, that such actions shall only require the Company’s
best efforts (or other specified standard) to the extent specifically provided for in this Warrant. 
 10. Certain
Adjustments. The Exercise Price and number of Warrant Shares issuable upon exercise of this Warrant are subject to adjustment from time to time as set forth in this Section 10. 

(a) Stock Dividends. If the Company, at any time while this Warrant is outstanding, pays a dividend on its Common Stock payable in
additional shares of Common Stock or otherwise makes a distribution on any class of capital stock that is payable in shares of Common Stock, then in each such case the Exercise Price shall be multiplied by a fraction, (A) the








 
numerator of which shall be the number of shares of Common Stock outstanding immediately prior to the opening of business on the day after the record date for the determination of stockholders
entitled to receive such dividend or distribution and (B) the denominator of which shall be the number of shares of Common Stock outstanding immediately after the distribution date of such dividend or distribution. Any adjustment made pursuant
to this Section 10(a) shall become effective immediately after the record date for the determination of stockholders entitled to receive such dividend or distribution; provided, however, that if following such record date the
Company rescinds or modifies such dividend or distribution, the Exercise Price shall be appropriately adjusted (as of the date that the Company effectively rescinds or modifies such dividend or distribution) to take into account the effect of such
rescinded or modified dividend or distribution on the Exercise Price pursuant to this Section 10(a). 
 (b) Stock
Splits. If the Company, at any time while this Warrant is outstanding, (i) subdivides outstanding shares of Common Stock into a larger number of shares, or (ii) combines outstanding shares of Common Stock into a smaller number of
shares, then in each such case the Exercise Price shall be multiplied by a fraction, (A) the numerator of which shall be the number of shares of Common Stock outstanding immediately before such event and (B) the denominator of which shall
be the number of shares of Common Stock outstanding immediately after such event. Any adjustment pursuant to this Section 10(b) shall become effective immediately after the effective date of such subdivision or combination. 

(c) Reclassifications. A reclassification of the Common Stock (other than any such reclassification in connection with a merger or
consolidation to which Section 10(e) applies) into shares of any other class of stock shall be deemed: 
 (i) a
distribution by the Company to the holders of its Common Stock of such shares of such other class of stock for the purposes and within the meaning of this Section 10; and 

(ii) if the outstanding shares of Common Stock shall be changed into a larger or smaller number of shares of Common Stock as part of
such reclassification, such change shall be deemed a subdivision or combination, as the case may be, of the outstanding shares of Common Stock for the purposes and within the meaning of Section 10(b). 

(d) Other Distributions. If the Company, at any time while this Warrant is outstanding, distributes to holders of Common Stock
(i) evidences of its indebtedness, (ii) shares of any class of capital stock, (iii) rights or warrants to subscribe for or purchase any shares of any class of capital stock or (iv) any other asset, other than a distribution of
Common Stock covered by Section 10(a), (in each case, “Distributed Property”), then in each such case the Exercise Price in effect immediately prior to the record date fixed for determination of stockholders
entitled to receive such distribution (and the Exercise Price thereafter applicable) shall be adjusted (effective on and after such record date) to equal the product of such Exercise Price multiplied by a fraction, (A) the numerator of which
shall be Market Price on such record date less the then fair market value of the Distributed Property distributed in respect of one outstanding share of Common Stock, which, if the Distributed Property is other than cash or marketable securities,
shall be as determined in good faith by the Board of Directors of the Company whose determination shall be described in a board resolution, and (B) the denominator 







 
of which shall be the Market Price on such record date; provided, however, that if following the record date for such distribution the Company rescinds or modifies such distribution, the
Exercise Price shall be appropriately adjusted (as of the date that the Company effectively rescinds or modifies such distribution) to take into account the effect of such rescinded or modified distribution on the Exercise Price pursuant to this
Section 10(d). 
 (e) Fundamental Transactions. If, at any time following the Initial Exercise Date,
(i) the Company effects any merger or consolidation of the Company with or into another Person, (ii) the Company effects any sale of all or substantially all of its assets in one or a series of related transactions or (iii) there
shall occur any merger of another Person into the Company whereby the Common Stock is cancelled, converted or reclassified into or exchanged for other securities, cash or property (in any such case, a “Fundamental
Transaction”), then, as a condition to the consummation of such Fundamental Transaction, the Company shall (or, in the case of any Fundamental Transaction in which the Company is not the surviving entity, the Company shall take all
reasonable steps to cause such other Person to) shall, at its election in its sole discretion: 
 (I) execute and deliver to
the Holder of this Warrant a written instrument providing that: 
 (x) so long as this Warrant remains outstanding, upon the
exercise hereof at any time on or after the consummation of such Fundamental Transaction and on such terms and subject to such conditions as shall be nearly equivalent as may be practicable to the provisions set forth in this Warrant, this Warrant
shall be exercisable into, in lieu of Common Stock issuable upon such exercise prior to such consummation, the securities or other property (the “Substituted Property”) that would have been received in connection with such
Fundamental Transaction by a holder of the number of shares of Common Stock into which this Warrant was exercisable immediately prior to such Fundamental Transaction, assuming such holder of Common Stock: 

(A) is not a Person with which the Company consolidated or into which the Company merged or which merged into the Company or to which
such sale or transfer was made, as the case may be (a “Constituent Person”), or an Affiliate of a Constituent Person; and 
 (B) failed to exercise such Holder’s rights of election, if any, as to the kind or amount of securities, cash and other property receivable in connection with such Fundamental Transaction
(provided, however, that if the kind or amount of securities, cash or other property receivable in connection with such Fundamental Transaction is not the same for each share of Common Stock held immediately prior to such Fundamental
Transaction by a Person other than a Constituent Person or an Affiliate thereof and in respect of which such rights of election shall not have been exercised (a “Non-Electing Share”), then, for the purposes of this
Section 10(e), the kind and amount of securities, cash and other property receivable in connection with such Fundamental Transaction by each Non-Electing Share shall be deemed to be the kind and amount so receivable per share by a
plurality of the Non-Electing Shares); and 
 (y) the rights and obligations of the Company (or, in the event of a transaction
in which the Company is not the surviving Person, such other Person) and the Holder in respect of Substituted Property shall be as nearly equivalent as may be practicable to the rights and obligations of the Company and Holder in respect of Common
Stock hereunder. 







 Such written instrument shall provide for adjustments which, for events subsequent to the
effective date of such written instrument, shall be as nearly equivalent as may be practicable to the adjustments provided for in this Section 10. The above provisions of this Section 10(e) shall similarly apply to successive
Fundamental Transactions, or 
 (II) cause to be delivered to the Holder, as soon as practicable following the closing of the
Fundamental Transaction, the Substituted Property less such portion of the Substituted Property with a value (determined in good faith by the Board of Directors of the Company or the other Person in the Fundamental Transaction) equal to the
aggregate Exercise Price of this Warrant. 
 (f) Adjustment of Warrant Shares. Simultaneously with any adjustment to the
Exercise Price pursuant to paragraphs (a) through (d) of this Section 10, the number of Warrant Shares that may be purchased upon exercise of this Warrant shall be increased or decreased proportionately, so that after such
adjustment the aggregate Exercise Price payable hereunder for the increased or decreased number of Warrant Shares shall be the same as the aggregate Exercise Price payable for the Warrant Shares immediately prior to such adjustment. 

(g) Calculations. All calculations under this Section 10 shall be made to the nearest cent or the nearest 1/100th of a
share, as applicable. The number of shares of Common Stock outstanding at any given time shall not include shares owned or held by or for the account of the Company, and the disposition of any such shares shall be considered an issue or sale of
Common Stock. 
 (h) Adjustments. Notwithstanding any provision of this Section 10, no adjustment of the
Exercise Price shall be required if such adjustment is less than $0.01; provided, however, that any adjustments which by reason of this Section 10(h) are not required to be made shall be carried forward and taken into account for
purposes of any subsequent adjustment required to be made hereunder. 
 (i) Notice of Adjustments. Upon the occurrence of
each adjustment pursuant to this Section 10, the Company will promptly deliver to the Holder a certificate executed by the Company’s Chief Financial Officer setting forth, in reasonable detail, the event requiring such adjustment
and the method by which such adjustment was calculated, the adjusted Exercise Price and the adjusted number or type of Warrant Shares or other securities issuable upon exercise of this Warrant (as applicable). The Company will retain at its office
copies of all such certificates and cause the same to be available for inspection at said office during normal business hours by the Holder or any prospective purchaser of the Warrant designated by the Holder. 

(j) Notice of Corporate Events. If the Company (i) declares a dividend or any other distribution of cash, securities or other
property in respect of its Common Stock, including, without limitation, any granting of rights or warrants to subscribe for or purchase any capital stock of the Company or any subsidiary of the Company, (ii) authorizes, approves, enters into
any agreement contemplating, or solicits stockholder approval for, any Fundamental Transaction or (iii) authorizes the voluntary dissolution, liquidation or winding up of the affairs of the








 
Company, then the Company shall deliver to the Holder a notice describing the material terms and conditions of such transaction at least 10 calendar days prior to the applicable record or
effective date on which a Person would need to hold Common Stock in order to participate in or vote with respect to such transaction, and the Company will take all steps reasonably necessary in order to ensure that the Holder is given the practical
opportunity to exercise this Warrant prior to such time so as to participate in or vote with respect to such transaction; provided, however, that the failure to deliver such notice or any defect therein shall not affect the validity of
the corporate action required to be described in such notice. 
 11. Registration Rights. 

(a) General. If at any time after the date hereof the Company proposes to register any of its Common Stock under the Securities
Act in connection with the public offering of such securities for its own account or for the accounts of shareholders other than Holder, solely for cash on a form that would also permit the registration of the Warrant Shares, the Company shall, each
such time, promptly give Holder written notice of such determination. Upon the written request of Holder given within fifteen (15) days after the giving of any such notice by the Company, the Company shall, subject to the limitations set forth
in Section 11(e), use its best efforts to cause to be registered under the Securities Act all of the Warrant Shares that Holder has requested be registered; provided, that the Company shall have the right to postpone or withdraw any
registration statement relating to an offering in which the Holder is eligible to participate under this Section 11 without any liability or obligation to the Holder under this Section 11. For the avoidance of doubt, the
Company shall not be obligated to effect any registration of Warrant Shares under this Section 11 incidental to the registration of any of its securities in connection with the Company’s Registration Statement on Form S-1 filed by
the Company in connection with the private placement of the Company’s Common Stock in June of 2008. 
 (i) Other
Contractual Obligations of the Company. Each exercise of all or part of the Warrant by the Holder pursuant to Section 5 herein shall serve as Holder’s acknowledgment and acceptance that the Holder’s rights under this
Section 11 as to the Warrant Shares received as the result of such exercise are subject to the contractual obligations of the Company as of the Effective Date, including the Company’s obligations to CytRx Corporation set out in the
Contribution Agreement dated as of April 30, 2007 between CytRx Corporation and the Company, as amended on July 28, 2008. 
 (b) Obligations of the Company. Whenever required under this Section 11 to use its best efforts to effect the registration of any Warrant Shares, the Company shall, as expeditiously as
reasonably possible: 
 (i) Prepare and file with the SEC a registration statement with respect to such Warrant Shares and use
its best efforts to cause such registration statement to become effective, and, upon the request of the Holder, keep such registration statement effective for a period of up to one (1) year or, if earlier, until the distribution contemplated in
the registration statement has been completed; provided, however, that (i) such one (1) year period shall be extended for a period of time equal to the period the Holder refrains from selling any securities included in such registration at
the request of an underwriter of Common Stock (or other securities) of the 







 
Company; and (ii) in the case of any registration of Warrant Shares on Form S-3 which are intended to be offered on a continuous or delayed basis, subject to compliance with applicable
SEC rules, such one (1) year period shall be extended for up to ninety (90) days, if necessary, to keep the registration statement effective until all such Warrant Shares are sold. 

(ii) Prepare and file with the SEC such amendments and supplements to such registration statement and the prospectus used in connection
with such registration statement as may be necessary to comply with the provisions of the Securities Act with respect to the disposition of all securities covered by such registration statement. 

(iii) Furnish to the Holder such numbers of copies of a prospectus, including a preliminary prospectus, in conformity with the
requirements of the Securities Act, and such other documents as they may reasonably request in order to facilitate the disposition of such Warrant Shares owned by it. 
 (iv) Use its best efforts to register and qualify the securities covered by such registration statement under such other securities or Blue Sky laws of such jurisdictions as shall be reasonably
appropriate for the distribution of the securities covered by the registration statement, provided that the Company shall not be required in connection therewith or as a condition thereto to qualify to do business or to file a general consent to
service of process in any such states or jurisdictions, and further provided that (anything in this Section 11 to the contrary notwithstanding with respect to the bearing of expenses) if any jurisdiction in which the securities shall be
qualified shall require that expenses incurred in connection with the qualification of the securities in that jurisdiction be borne by shareholders, then such expenses shall be payable by the Holder to the extent required by such jurisdiction.

 (v) Provide a transfer agent for the Common Stock no later than the effective date of the first registration of any Warrant
Shares. 
 (vi) Otherwise use its best efforts to comply with all applicable rules and regulations of the SEC. 

(vii) Use its best efforts to cause all such Warrant Shares to be listed on a national securities exchange (if such securities are
not already so listed) and on each additional national securities exchange on which similar securities issued by the Company are then listed, if the listing of such securities is then permitted under the rules of such exchange. 

(viii) Use every reasonable effort to prevent the issuance of any stop order suspending the effectiveness of such registration statement
or of any order preventing or suspending the use of any preliminary prospectus and, if any such order is issued, to obtain the lifting thereof at the earliest reasonable time. 
 (c) Furnish Information. It shall be a condition precedent to the obligations of the Company to take any action pursuant to this Section 11 with respect to the registration of any of
the Holder’s Warrant Shares that the Holder shall take such actions and furnish to the Company such information regarding itself, the Warrant Shares held by it, and the intended method of disposition of such securities, as the Company shall
reasonably request and as shall be required in connection with any registration, qualification or compliance referred to in this agreement, 







 
including, without limitation (i) in connection with an underwritten offering, enter into an appropriate underwriting agreement containing terms and provisions then customary in agreements
of that nature, (ii) enter into such custody agreements, powers of attorney and related documents at such time and on such terms and conditions as may then be customarily required in connection with such offering and (iii) distribute the
Warrant Shares only in accordance with and in the manner of the distribution contemplated by the applicable registration statement and prospectus. In addition, the Holder shall promptly notify the Company of any request by the Commission or any
state securities commission or agency for additional information or for such registration statement or prospectus to be amended or supplemented. 
 (d) Registration Expenses. All expenses (excluding underwriters’ discounts and commissions) incurred in connection with any registration pursuant to this Section 11 including,
without limitation, any additional registration and qualification fees and any additional fees and disbursements of counsel to the Company that result from the inclusion of securities held by the Holder in such registration, shall be borne by the
Company whether or not the registration statement to which such registration expenses relate becomes effective. 
 (e)
Underwriting Requirements. 
 (i) In connection with any offering under this Section 11 involving an
underwriting of shares being issued by the Company, the Company shall not be required to include any Warrant Shares in such underwriting unless the Holder accepts the terms of the underwriting as agreed upon between the Company and the underwriters
selected by it, and then only in such quantity as will not, in the sole discretion of the underwriters, jeopardize the success of the offering by the Company. If the total amount of securities that the Holder requests to be included in an
underwritten offering under this Section 11 exceeds the amount of securities that the underwriters reasonably believe compatible with the success of the offering, the Company may exclude some or all of the Warrant Shares from such
registration and underwriting. 
 (ii) With respect to any underwritings of shares to be registered under this
Section 11, the Company shall have the right to designate the managing underwriter or underwriters. 
 (f) Delay
of Registration. The Holder shall not have any right to take any action to restrain, enjoin, or otherwise delay any registration as the result of any controversy that might arise with respect to the interpretation or implementation of this
Section 11. 
 (g) Indemnification. In the event any Warrant Shares are included in a registration statement
under this Section 11: 
 (i) To the extent permitted by law, in connection with any registration statement in
which Warrant Shares are included, the Company will indemnify and hold harmless the Holder and its officers, directors and stockholders, legal counsel and accountants for the Holder, any underwriter (as defined in the Securities Act) for the Holder
and each person, if any, who controls the Holder or underwriter within the meaning of the Securities Act or the 1934 Act, against any losses, claims, damages or liabilities, joint or several, to which they may become subject under the Securities Act
or otherwise, insofar as such losses, claims, damages or 







 
liabilities (or actions in respect thereof) arise out of or are based on (i) any untrue or alleged untrue statement of any material fact contained in such registration statement, including,
without limitation, any prospectus or final prospectus contained therein or any amendments or supplements thereto, (ii) the omission or alleged omission to state therein a material fact required to be stated therein, or necessary to make the
statements therein not misleading or (iii) any violation by the Company of any rule or regulation promulgated under the Securities Act applicable to the Company and relating to action or inaction required of the Company in connection with any
such registration; and will promptly reimburse the Holder, and any underwriter, controlling person or other aforementioned person for any legal or other expenses reasonably incurred by them in connection with investigating or defending any such
loss, claim, damage, liability, or action, provided, however, that the indemnity agreement contained in this Section 11g(i) shall not apply to amounts paid in settlement of any such loss, claim, damage, liability or action if such
settlement is effected without the consent of the Company (which consent shall not be unreasonably withheld or delayed) nor shall the Company be liable to the Holder, or any underwriter, controlling person or other aforementioned person in any such
case for any such loss, claim, damage, liability or action to the extent that it (i) arises out of or is based upon an untrue statement or alleged untrue statement or omission or alleged omission made in connection with such registration
statement, preliminary prospectus, final prospectus, or amendments or supplements thereto, in reliance upon and in conformity with written information furnished to the Company expressly for use in connection with such registration by or on behalf of
the Holder, or any underwriter, controlling person or other aforementioned person, (ii) is caused by the failure of the Holder to deliver a copy of the final prospectus relating to such Warrant Shares, as then amended or supplemented, in
connection with a purchase, if the Company had previously furnished copies thereof to the Holder or (iii) is caused by the Holder’s disposition of Warrant Shares during any period during which the Holder is obligated to discontinue any
disposition of Warrant Shares under Section 11(j). 
 (ii) To the extent permitted by law, the Holder will
indemnify and hold harmless the Company, each of its directors, each of its officers who has signed the registration statement, each person, if any, who controls the Company within the meaning of the Securities Act, and any underwriter (within the
meaning of the Securities Act) for the Company against any losses, claims, damages or liabilities to which the Company or any such director, officer, controlling person or underwriter may become subject, under the Securities Act or otherwise,
insofar as such losses, claims, damages or liabilities (or actions in respect thereto) arise out of or are based upon (i) any untrue statement or alleged untrue statement of any material fact contained in such registration statement, including
any prospectus or final prospectus contained therein or any amendments or supplements thereto or (ii) the omission or alleged omission to state therein a material fact required to be stated therein or necessary to make the statements therein
not misleading, in each case to the extent, but only to the extent, that such untrue statement or alleged untrue statement or omission or alleged omission was made in reliance upon and in conformity with written information relating to and furnished
to the Company by the Holder expressly for use in connection with such registration; and will promptly reimburse the Company or any such director, officer, controlling person or underwriter for any legal or other expenses reasonably incurred by them
in connection with investigating or defending any such loss, claim, damage, liability or action; provided, however, that the indemnity agreement contained in this Section 11(g)(ii) shall not apply to amounts paid in settlement of any
such loss, claim, damage, liability or action if such settlement is effected without the consent of the Holder 







 
(which consent shall not be unreasonably withheld or delayed) and provided further that the Holder shall not have any liability under this Section 11(g)(ii) in excess of the net
proceeds actually received by the Holder in the relevant public offering. 
 (iii) Promptly after receipt by an indemnified
party under this Section 11(g) of notice of the commencement of any action, such indemnified party will, if a claim in respect thereof is to be made against any indemnifying party under this Section 11(g), notify the
indemnifying party in writing of the commencement thereof and the indemnifying party shall have the right to participate in, and, to the extent the indemnifying party so desires, jointly with any other indemnifying party similarly noticed, to assume
the defense thereof with counsel mutually satisfactory to the parties. The failure to notify an indemnifying party promptly of the commencement of any such action, if prejudicial to his ability to defend such action, shall relieve such indemnifying
party of any liability to the indemnified party under this Section 11(g), but the omission so to notify the indemnifying party will not relieve him of any liability that he may have to any indemnified party otherwise than under this
Section 11(g). 
 (iv) If the indemnification provided for in this Section 11(g) is required by its
terms but is for any reason held to be unavailable to or otherwise insufficient to hold harmless an indemnified party under Section 11(g)(i) or Section 11(g)(ii) in respect of any losses, claims, damages, liabilities or
expenses referred to herein, then each applicable indemnifying party shall contribute to the amount paid or payable by such indemnified party as a result of any losses, claims, damages, liabilities or expenses referred to herein in such proportion
as is appropriate to reflect the relative fault of the Company and the Holder in connection with the statements or omissions described in such Section 11(g)(i) or Section 11(g)(ii) which resulted in such losses, claims,
damages, liabilities or expenses, as well as any other relevant equitable considerations. The relative fault of the Company and the Holder shall be determined by reference to, among other things, whether the untrue or alleged untrue statement of a
material fact or the omission or alleged omission to state a material fact relates to information supplied by the Company or the Holder and the parties’ relative intent, knowledge, access to information and opportunity to correct or prevent
such statement or omission. The amount paid or payable by a party as a result of the losses, claims, damages, liabilities and expenses referred to above shall be deemed to include, subject to the limitations set forth in this
Section 11(g), any legal or other fees or expenses reasonably incurred by such party in connection with investigating or defending any action or claim. The provisions set forth in Section 11(g)(iii) with respect to notice of
commencement of any action shall apply if a claim for contribution is to be made under this Section 11(g)(iv); provided, however, that no additional notice shall be required with respect to any action for which notice has been given
under Section 11(g)(iii) for purposes of indemnification. The Company and the Holder agree that it would not be just and equitable if contribution pursuant to this Section 11(g) were determined solely by pro rata allocation
or by any other method of allocation which does not take account of the equitable considerations referred to in this paragraph. Notwithstanding the provisions of this Section 11(g)(iv), the Holder shall not be required to contribute an
amount in excess of the net proceeds actually received by the Holder in the relevant public offering. No person guilty of fraudulent misrepresentation (within the meaning of Section 11(f) of the Securities Act) shall be entitled to contribution
from any person who was not guilty of such fraudulent misrepresentation. 







 (h) Payment of Expenses. The Company shall pay all reasonable expenses of the Holder
(including the reasonable expenses of legal counsel for such Holder) incurred in connection with each registration of Warrant Shares requested pursuant to this Section 11, other than underwriting discount and commission, if any, and
applicable transfer taxes, if any. 
 (i) No Transfer of Registration Rights. The registration rights and obligations of
the Holder under this Exhibit with respect to any Warrant Shares may not be transferred to any third party other than any acquirer of all or substantially all of the assets or outstanding shares of stock of the Holder or any entity that merges with
or into the Holder. 
 (j) Future Events. If the Holder is at the time participating in a registration of Warrant Shares
requested pursuant to this Section 11, the Company will notify the Holder of the occurrence of any of the following events of which the Company is actually aware, and when so notified, the Holder will immediately discontinue any
disposition of Warrant Shares until notified by the Company that such event is no longer applicable: 
 (i) the issuance by the
Commission or any state securities commission or agency of any stop order suspending the effectiveness of the registration statement or the initiation of any proceedings for that purpose (in which case the Company will make reasonable efforts to
obtain the withdrawal of any such order or the cessation of any such proceedings); or 
 (ii) the existence of any fact which
makes untrue any material statement made in the registration statement or prospectus or any document incorporated therein by reference or which requires the making of any changes in the registration statement or prospectus or any document
incorporated therein by reference in order to make the statements therein not misleading (in which case the Company will make reasonable efforts to amend the applicable document to correct the deficiency). 

(k) Termination of Rights. The rights of the Holder pursuant to this Section 11 shall terminate and be of no further force
and effect on the earlier of (i) the date that all Warrant Shares have been sold by the Holder or (ii) the date that all Warrant Shares may be sold in any three month period pursuant to Rule 144(b) promulgated under the Securities Act of
1933, as amended. 
 12. Fractional Shares. The Company shall not be required to issue or cause to be issued fractional
Warrant Shares on the exercise of this Warrant. If any fraction of a Warrant Share would, except for the provisions of this Section 12, be issuable upon exercise of this Warrant, the Company shall make a cash payment to the Holder equal
to (a) such fraction multiplied by (b) the Market Price on the Exercise Date of one full Warrant Share. 
 13.
Remedies. The Company stipulates that the remedies at law of the Holder of this Warrant in the event of any default or threatened default by the Company in the performance of or compliance with any of the terms of this Warrant are not and
will not be adequate, and that such terms may be specifically enforced by a decree for the specific performance of any agreement contained herein or by an injunction against a violation of any of the terms hereof or otherwise. 

14. Notices. Any and all notices or other communications or deliveries hereunder (including without limitation any Exercise
Notice) shall be in writing and shall be mailed by 







 
certified mail, return receipt requested, or by a nationally recognized courier service or delivered (in person or by facsimile), against receipt to the party to whom such notice or other
communication is to be given. Any notice or other communication given by means permitted by this Section 14 shall be deemed given at the time of receipt thereof. The address for such notices or communications shall be as set forth below:

  

			
	If to the Company:	 	Mark J. Ahn
		 	Chief Executive Officer
		 	RXi Pharmaceuticals Corporation
		 	60 Prescott Street
		 	Worcester, Massachusetts 01605
		 	Fax: 888-552-7581
		
	    If to the Holder:	 	Legend Securities, Inc.
		 	Attention: Salvatore C. Caruso
		 	45 Broadway 32nd Floor
		 	New York, NY 10006
		 	Phone: 212-344-5747 ext 231
		 	Fax: 212-898-1224

 Or such other address as is provided to such other party in accordance with this Section 14. 

15. Warrant Agent. The Company shall serve as warrant agent under this Warrant. Upon a prompt written notice to the Holder, the
Company may appoint a new warrant agent. Any Person into which any new warrant agent may be merged, any Person resulting from any consolidation to which any new warrant agent shall be a party or any Person to which any new warrant agent transfers
substantially all of its corporate trust or shareholders services business shall be a successor warrant agent under this Warrant without any further act. Any such successor warrant agent shall promptly cause notice of its succession as warrant agent
to be mailed (by first class mail, postage prepaid) to the Holder at the Holder’s last address as shown on the Warrant Register. 
 16. Miscellaneous. 
 (a) This Warrant may not be assigned by the Holder
except to a Permitted Transferee. This Warrant may not be assigned by the Company, except to a successor in the event of a Fundamental Transaction. This Warrant shall be binding on and inure to the benefit of the parties hereto and their respective
permitted successors and assigns. Subject to the preceding sentence, nothing in this Warrant shall be construed to give to any Person other than the Company and the Holder any legal or equitable right, remedy or cause of action under this Warrant.
This Warrant may be amended only in writing signed by the Company and the Holder and their permitted successors and assigns. 

(b) The Company will not, by amendment of its governing documents or through any reorganization, transfer of assets, consolidation,
merger, dissolution, issue or sale of securities or any other voluntary action, avoid or seek to avoid the observance or performance of any of the terms of this Warrant, but will at all times in good faith assist in the carrying out of all such








 
terms and in the taking of all such action as may be necessary or appropriate in order to protect the rights of the Holder against impairment. Without limiting the generality of the foregoing,
the Company (i) will not increase the par value of any Warrant Shares above the amount payable therefor upon exercise thereof, and (ii) will take all such action as may be reasonably necessary or appropriate in order that the Company may
validly and legally issue fully paid and nonassessable Warrant Shares on the exercise of this Warrant, free from all taxes, liens, claims and encumbrances and (iii) will not close its shareholder books or records in any manner which interferes
with the timely exercise of this Warrant. 
 (c) This Warrant shall be governed by and construed and enforced in accordance with
the laws of the Commonwealth of Massachusetts. Each party hereby irrevocably submits to the exclusive jurisdiction of the state and Federal courts sitting in the City of Boston, Massachusetts, for the adjudication of any dispute hereunder or in
connection herewith or with any transaction contemplated hereby or discussed herein, and hereby irrevocably waives, and agrees not to assert in any suit, action or proceeding that it is not personally subject to the jurisdiction of any such court or
that such suit, action or proceeding is improper. Each party hereby irrevocably waives personal service of process and consents to process being served in any such suit, action or proceeding by mailing a copy thereof via registered or certified mail
or overnight delivery (with evidence of delivery) to such party at the address in effect for notices to it under this Warrant and agrees that such service shall constitute good and sufficient service of process and notice thereof. Nothing contained
herein shall be deemed to limit in any way any right to serve process in any manner permitted by law. THE PARTIES HEREBY WAIVE ALL RIGHTS TO A TRIAL BY JURY. 
 (d) Neither party shall be deemed in default of any provision of this Warrant, to the extent that performance of its obligations or attempts to cure a breach hereof are delayed or prevented by any event
reasonably beyond the control of such party, including, without limitation, war, hostilities, acts of terrorism, revolution, riot, civil commotion, national emergency, strike, lockout, unavailability of supplies, epidemic, fire, flood, earthquake,
force of nature, explosion, embargo, or any other Act of God, or any law, proclamation, regulation, ordinance, or other act or order of any court, government or governmental agency, provided that such party gives the other party written
notice thereof promptly upon discovery thereof and uses reasonable efforts to cure or mitigate the delay or failure to perform. 

(e) The headings herein are for convenience only, do not constitute a part of this Warrant and shall not be deemed to limit or affect any
of the provisions hereof. 
 (f) In case any one or more of the provisions of this Warrant shall be deemed invalid or
unenforceable in any respect, the validity and enforceability of the remaining terms and provisions of this Warrant shall not in any way be affected or impaired thereby and the parties will attempt in good faith to agree upon a valid and enforceable
provision which shall be a commercially reasonable substitute therefor, and upon so agreeing, shall incorporate such substitute provision in this Warrant. 
 [REMAINDER OF PAGE INTENTIONALLY LEFT BLANK, 
 SIGNATURE PAGE FOLLOWS] 







 IN WITNESS WHEREOF, the Company has caused this Warrant to be duly executed by its
authorized officer as of the date first indicated above. 
  

			
	RXI PHARMACEUTICALS CORPORATION
		
	By:	 	 /s/ Mark J. Ahn

		 	Mark J. Ahn, President & CEO
	
	Acknowledged and Agreed:
	
	 /s/ Salvatore C. Caruso

	Salvatore C. Caruso, Legend Securities, Inc.









 APPENDIX A 
 FORM OF ASSIGNMENT 
 (to be completed and signed only upon transfer of Warrant)

 FOR VALUE RECEIVED, the undersigned hereby sells, assigns and transfers unto Legend Securities the right represented by the
within Warrant to purchase 150,000 shares of Common Stock of RXi Pharmaceuticals Corporation to which the within warrant relates and appoints
                     attorney to transfer said right on the books of RXi Pharmaceuticals Corporation with full power of substitution in the
premises. 
  

											
	Dated:	 	  
	 		 		 	  

		 		 		 		 	(Signature must conform in all respects to name of Holder as specified on face of the Warrant)
						
		 		 		 		 	Address of Transferee:	 	
						
		 		 		 		 	 Legend Securities, Inc.
	 	
						
		 		 		 		 	 Attention: Salvatore C. Caruso
	 	
						
		 		 		 		 	 45 Broadway, 32nd Floor
	 	
						
		 		 		 		 	 New York, NY 10006
	 	

  

	
	In the presence of:
	
	  









 APPENDIX B 
 NOTICE OF EXERCISE 
 TO: RXI PHARMACEUTICALS CORPORATION 

(1) The undersigned hereby elects to purchase              Warrant Shares of
the Company pursuant to the terms of the attached Warrant (only if exercised in full), and tenders herewith payment of the exercise price in full, together with all applicable transfer taxes, if any. 

(2) Payment shall take the form of (check applicable box): 
 [  ] in lawful money of the United States; or 
 [  ] [if
permitted] the cancellation of such number of Warrant Shares as is necessary, in accordance with the formula set forth in subsection 2(c), to exercise this Warrant with respect to the maximum number of Warrant Shares purchasable pursuant to the
cashless exercise procedure set forth in subsection 2(c). 
 (3) Please issue a certificate or certificates representing said
Warrant Shares in the name of the undersigned or in such other name as is specified below: 
  

	
	  


 The Warrant Shares shall be delivered to the following DWAC Account Number or by physical delivery of a certificate to:

  

	
	  

	
	  

	
	  


  

					
	[SIGNATURE OF HOLDER]	 		 	


					
			
	Name of Investing Entity:	 	  
	 	


					
	Signature of Authorized Signatory of Investing Entity:	 	  
	 	


					
	Name of Authorized Signatory:	 	  
	 	


					
	Title of Authorized Signatory:	 	  
	 	


					
	Date: