EX-4.3



 Exhibit 4.3 

COMMON STOCK PURCHASE WARRANT 

RXi PHARMACEUTICALS CORPORATION 
  

			
	Warrant Shares:                     	  	Initial Exercise Date:                     , 2016

 THIS COMMON STOCK PURCHASE WARRANT (the “Warrant”) certifies that, for value received,
                     or its assigns (the “Holder”) is entitled, upon the terms and subject to the limitations on exercise and
the conditions hereinafter set forth, at any time on or after                     , 2016 (the “Initial Exercise Date”) and on
or prior to the close of business on the                      year anniversary of the Initial Exercise Date (the “Termination
Date”) but not thereafter, to subscribe for and purchase from RXi PHARMACEUTICALS CORPORATION, a Delaware corporation (the “Company”), up to
                     shares (as subject to adjustment hereunder, the “Warrant Shares”) of the Company’s common stock,
par value $0.0001 per share (the “Common Stock”). The purchase price of one share of Common Stock under this Warrant shall be equal to the Exercise Price, as defined in Section 2(b). This Warrant is initially being issued in
book-entry form and shall initially be represented only by one or more global certificates deposited with the Depository Trust Company (“DTC”) and registered in the name of Cede & Co., a nominee of DTC, or as otherwise directed by
DTC. Cede & Co., a nominee of The Depository Trust Company (the “Depositary”). Ownership of beneficial interests in the Warrants shall be shown on, and the transfer of such ownership shall be effected through, records
maintained by (i) the Depositary or its nominee for each Global Warrant or (ii) institutions that have accounts with the Depositary (such institution, with respect to a Warrant in its account, a “Participant”). 

Section 1. Definitions. In addition to the terms defined elsewhere in this Warrant, the following terms have the meanings
indicated in this Section 1: 
 “Affiliate” means any Person that, directly or indirectly through one
or more intermediaries, controls or is controlled by or is under common control with a Person, as such terms are used in and construed under Rule 405 under the Securities Act. 

“Business Day” means any day except any Saturday, any Sunday, any day which is a federal legal holiday in the
United States or any day on which banking institutions in the State of New York are authorized or required by law or other governmental action to close. 

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

“Common Stock Equivalents” means any securities of the Company or its subsidiaries that would entitle the
holder thereof to acquire at any time Common Stock, including, without limitation, any debt, preferred stock, right, option, warrant or other instrument that is at any time convertible into or exercisable or exchangeable for, or otherwise entitles
the holder thereof to receive, Common Stock. 

  
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 “Exchange Act” means the Securities Exchange Act of 1934, as
amended, and the rules and regulations promulgated thereunder. 
 “Person” means an 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. 

“Securities Act” means the Securities Act of 1933, as amended, and the rules and regulations promulgated
thereunder. 
 “Trading Day” means a day on which the Common Stock is traded on a Trading Market, and if the
Common Stock is not then listed or quoted for trading on a Trading Market, Trading Day shall mean a Business Day. 

“Trading Market” means any of the following markets or exchanges on which the Common Stock is listed or quoted
for trading on the date in question: the NYSE Mkt, the Nasdaq Capital Market, the Nasdaq Global Market, the Nasdaq Global Select Market, the New York Stock Exchange or the OTCQB (or any successors to any of the foregoing). 

“Transfer Agent” means Computershare Trust Company, N.A., the current transfer agent of the Company, with a
mailing address of 250 Royall Street, Canton, Massachusetts, and any successor transfer agent of the Company. 

“Warrant Agency Agreement” means that certain warrant agency agreement, dated as of or prior to the Initial
Exercise Date, between the Company and the Transfer Agent. 
 “Warrant Agent” means Computershare Inc., a
Delaware corporation, and its wholly-owned subsidiary, Computershare Trust Company, N.A., a federally chartered trust company. 

Section 2. Exercise. 

a) Exercise of the purchase rights represented by this Warrant may be made, in whole or in part, at any time or times on or
after the Initial Exercise Date and on or before the Termination Date by delivery to DTC through the Holder’s broker, if the Warrant is held in book-entry form, or to the Warrant Agent, if the Warrant is held in certificated form (or such other
office or agency of the Company as it may designate by notice in writing to the registered Holder at the address of the Holder appearing on the books of the Company) of a duly executed facsimile copy (or e-mail attachment) or other method of
delivery of the Notice of Exercise in the form annexed hereto. Within the earlier of (i) three (3) Trading Days and (ii) the number of Trading Days comprising the Standard Settlement Period (as defined in Section 2(d)(i) herein)
following the date the Notice of Exercise is delivered to DTC or the Warrant Agent, as applicable, the Holder shall deliver the aggregate Exercise Price for the shares specified in the applicable Notice of Exercise by wire transfer or cashier’s
check drawn on a United States bank, unless the cashless exercise procedure specified in Section 2(c) below is specified in the applicable 

  
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Notice of Exercise. No ink-original Notice of Exercise shall be required, nor shall any medallion guarantee (or other type of guarantee or notarization) of any Notice of Exercise form be
required, so long as the Warrant Shares are to be issued to the Holder of the Warrant. Notwithstanding anything herein to the contrary, the Holder shall not be required to physically surrender this Warrant to the Warrant Agent, if the warrant is in
certificated form, until the Holder has purchased all of the Warrant Shares available hereunder and the Warrant has been exercised in full, in which case, the Holder shall surrender this Warrant to the Warrant Agent for cancellation within three
(3) Trading Days of the date the final Notice of Exercise is delivered to the Warrant Agent. Partial exercises of this Warrant resulting in purchases of a portion of the total number of Warrant Shares available hereunder shall have the effect
of lowering the outstanding number of Warrant Shares purchasable hereunder in an amount equal to the applicable number of Warrant Shares purchased. The Holder and the Warrant Agent shall maintain records showing the number of Warrant Shares
purchased and the date of such purchases. The Warrant Agent shall deliver any objection to any Notice of Exercise within one (1) Business Day of receipt of such notice. The Holder and any assignee, by acceptance of this Warrant or any
partial assignment of this Warrant, acknowledge and agree that, by reason of the provisions of this paragraph, following the purchase or assignment of a portion of the Warrant Shares hereunder, the number of Warrant Shares available for purchase
hereunder at any given time may be less than the amount stated on the face hereof. 
 b) Exercise Price. The
exercise price per share of the Common Stock under this Warrant shall be $[            ], subject to adjustment hereunder (the “Exercise Price”). 

c) Cashless Exercise. If at the time of exercise hereof there is no effective registration statement registering, or the
prospectus contained therein is not available for the issuance of the Warrant Shares to the Holder, then this Warrant may only be exercised, in whole or in part, at such time by means of a “cashless exercise” in which the Holder shall be
entitled to receive a number of Warrant Shares equal to the quotient obtained by dividing [(A-B) * (X)] by (A) (the “Cashless Exercise Ratio”), where: 
  

	 	(A)	= the last VWAP immediately preceding the time of delivery of the Notice of Exercise giving rise to the applicable “cashless exercise”, as set forth in the applicable Notice of Exercise (to clarify, the
“last VWAP” will be the last VWAP as calculated over an entire Trading Day such that, in the event that this Warrant is exercised at a time that the Trading Market is open, the prior Trading Day’s VWAP shall be used in this
calculation); 

  

	 	(B)	= the Exercise Price of this Warrant, as adjusted hereunder; and 

  

	 	(X)	= the number of Warrant Shares that would be issuable upon exercise of this Warrant in accordance with the terms of this Warrant if such exercise were by means of a cash exercise rather than a cashless exercise.


 If Warrant Shares are issued in such a cashless exercise, the parties acknowledge and agree that in
accordance with Section 3(a)(9) of the Securities Act, the Warrant Shares shall take on the registered characteristics of the Warrants being exercised. The Company agrees not to take any position contrary to this Section 2(c). 

  
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 The Warrant Agent shall have no obligation under this Warrant to calculate the
Cashless Exercise Ratio. The number of shares of Common Stock to be issued on such exercise will be determined pursuant to the formula above (with written notice thereof to the Warrant Agent) using the formula set forth in this
Section 2(c). The Warrant Agent shall have no duty or obligation to investigate or confirm whether the number of shares of Common Stock to be issued on such exercise, pursuant to this Section 2(c), is accurate or
correct. 
 “VWAP” means, for any date, the price determined by the first of the following clauses that
applies: (a) if the Common Stock is then listed or quoted on a Trading Market, the daily volume weighted average price of the Common Stock for such date (or the nearest preceding date) on the Trading Market on which the Common Stock is then
listed or quoted as reported by Bloomberg L.P. (based on a Trading Day from 9:30 a.m. (New York City time) to 4:00 p.m. (New York City time)), (b) if OTCQB or OTCQX is not a Trading Market, the volume weighted average price of the Common Stock
for such date (or the nearest preceding date) on OTCQB or OTCQX as applicable, (c) if the Common Stock is not then listed or quoted for trading on OTCQB or OTCQX and if prices for the Common Stock are then reported in the “Pink
Sheets” published by OTC Markets Group, Inc. (or a similar organization or agency succeeding to its functions of reporting prices), the most recent bid price per share of the Common Stock so reported, or (d) in all other cases, the fair
market value of a share of Common Stock as mutually determined by the Company and the Holder, provided that, if the Company and the Holder are unable to agree upon the fair market value of such security, then the fair market value will be determined
by an independent appraiser selected in good faith by the purchasers of a majority in interest of the securities then outstanding and reasonably acceptable to the Company, the fees and expenses of which shall be paid by the Company. 

d) Mechanics of Exercise. 

i. Delivery of Warrant Shares Upon Exercise. The Warrant Agent shall cause the Warrant Shares purchased hereunder to be
transmitted by the Transfer Agent to the Holder by crediting the account of the Holder’s or its designee’s balance account with The Depository Trust Company through its Deposit or Withdrawal at Custodian system (“DWAC”) if
the Company is then a participant in such system and either (A) there is an effective registration statement permitting the issuance of the Warrant Shares to or resale of the Warrant Shares by Holder or (B) this Warrant is being exercised
via cashless exercise, and otherwise by physical delivery of a certificate, registered in the Warrant Agent’s share register in the name of the Holder or its designee, for the number of Warrant Shares to which the Holder is entitled pursuant to
such exercise to the address specified by the Holder in the Notice of Exercise by the date that is the earlier of (i) three (3) Trading Days and (ii) the number of 

  
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 Trading Days comprising the Standard Settlement Period after the delivery to the Warrant Agent
or DTC, as applicable, of a properly completed and executed Notice of Exercise (such date, the “Warrant Share Delivery Date”), provided that the Holder has paid any required Exercise Price (or utilized “cashless exercise”)
for the portion of this Warrant being exercised on or prior to such Warrant Share Delivery Date. Upon delivery of the properly completed and executed Notice of Exercise or upon a beneficial owner of this Warrant instructing its DTC participant to
deliver a Notice of Exercise, the Holder shall be deemed for all corporate purposes to have become the holder of record of the Warrant Shares with respect to which this Warrant has been exercised, irrespective of the date of delivery of the Warrant
Shares, provided that payment of the aggregate Exercise Price (other than in the case of a cashless exercise) is received within the earlier of (i) three Trading Days and (ii) the number of Trading Days comprising the Standard Settlement
Period following delivery of the Notice of Exercise. If the Transfer Agent fails for any reason to deliver to the Holder the Warrant Shares subject to a properly completed and executed Notice of Exercise by the Warrant Share Delivery Date, and the
Holder has paid any required Exercise Price for the portion of this Warrant being exercised on or prior to such Warrant Share Delivery Date (or utilized “cashless exercise”), the Company shall pay to the Holder, in cash, as liquidated
damages and not as a penalty, for each $1,000 of Warrant Shares subject to such exercise (based on the VWAP of the Common Stock on the date of the applicable Notice of Exercise), $5 per Trading Day for each Trading Day after the second Trading Day
following the Warrant Share Delivery Date until such Warrant Shares are delivered or Holder rescinds such exercise. The Company agrees to maintain a transfer agent that is a participant in the FAST program so long as this Warrant remains outstanding
and exercisable. As used herein, “Standard Settlement Period” means the standard settlement period, expressed in a number of Trading Days, on the Company’s primary Trading Market with respect to the Common Stock as in effect on
the date of delivery of the Notice of Exercise. 
 ii. Delivery of New Warrants Upon Exercise. If this Warrant shall
have been exercised in part, the Company shall, at the request of a Holder and upon surrender of this Warrant, at the time of delivery of the Warrant Shares, deliver to the Holder a new Warrant evidencing the rights of the Holder to purchase the
unpurchased Warrant Shares called for by this Warrant, which new Warrant shall in all other respects be identical with this Warrant. 

iii. Rescission Rights. In the event that the Buy-In remedy pursuant to Section 2(d)(i) below does not apply or is
otherwise not exercised, if the Warrant Agent fails to cause the Transfer Agent to transmit to the Holder the Warrant Shares pursuant to Section 2(d)(i) by the Warrant Share Delivery Date and the Holder has paid any required Exercise Price for
the portion of this Warrant being exercised on or prior to such Warrant Share Delivery Date (or utilized “cashless exercise”), then the Holder will have the right to rescind such exercise. 

  
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 iv. Compensation for Buy-In on Failure to Timely Deliver Warrant Shares Upon
Exercise. In addition to any other rights available to the Holder, if the Warrant Agent fails to cause the Transfer Agent to transmit to the Holder the Warrant Shares in accordance with the provisions of Section 2(d)(i) above pursuant to an
exercise on or before the Warrant Share Delivery Date and the Holder has paid any required Exercise Price for the portion of this Warrant being exercised on or prior to such Warrant Share Delivery Date (or utilized “cashless exercise”),
and if after such date the Holder is required by its broker to purchase (in an open market transaction or otherwise) or the Holder’s brokerage firm otherwise purchases, shares of Common Stock to deliver in satisfaction of a sale by the Holder
of the Warrant Shares which the Holder anticipated receiving upon such exercise (a “Buy-In”), then the Company shall (A) pay in cash to the Holder the amount, if any, by which (x) the Holder’s total purchase price
(including customary brokerage commissions, if any) for the shares of Common Stock so purchased exceeds (y) the amount obtained by multiplying (1) the number of Warrant Shares that the Warrant Agent was required to deliver to the Holder in
connection with the exercise at issue times (2) the price at which the sell order giving rise to such purchase obligation was executed, and (B) at the option of the Holder, either reinstate the portion of the Warrant and equivalent number
of Warrant Shares for which such exercise was not honored (in which case such exercise shall be deemed rescinded, provided, however, that such right to reinstate or rescind shall only apply in the event that the rights pursuant to
Section 2(d)(iii) above have not been exercised) or deliver to the Holder the number of shares of Common Stock that would have been issued had the Warrant Agent timely complied with its exercise and delivery obligations hereunder. For example,
if the Holder purchases Common Stock having a total purchase price of $11,000 to cover a Buy-In with respect to an attempted exercise of shares of Common Stock with an aggregate sale price giving rise to such purchase obligation of $10,000, under
clause (A) of the immediately preceding sentence the Company shall be required to pay the Holder $1,000. The Holder shall provide the Warrant Agent written notice indicating the amounts payable to the Holder in respect of the Buy-In and, upon
request of the Warrant Agent or the Company, evidence of the amount of such loss. Nothing herein shall limit a Holder’s right to pursue any other remedies available to it hereunder, at law or in equity including, without limitation, a decree of
specific performance and/or injunctive relief with respect to the Warrant Agent’s failure to timely deliver shares of Common Stock upon exercise of the Warrant as required pursuant to the terms hereof. Notwithstanding anything to the contrary
in the foregoing, any amounts payable by the Company to the Holder pursuant to this Section 2(d)(iv) shall be reduced by any liquidated damages amounts that have been paid to such Holder by the Company pursuant to Section 2(d)(i). 

v. No Fractional Shares or Scrip. No fractional shares or scrip representing fractional shares shall be issued upon the
exercise of this Warrant. As to any fraction of a share which the Holder would otherwise be entitled to purchase upon such exercise, the Company shall, at its election, either pay a cash adjustment in respect of such final fraction in an amount
equal to such fraction multiplied by the Exercise Price or round up to the next whole share. 
 vi. Charges, Taxes and
Expenses. Issuance of Warrant Shares shall be made without charge to the Holder for any issue or transfer tax or other incidental expense in respect of the issuance of such Warrant Shares, all of which taxes and expenses shall be paid by the
Company, and such Warrant Shares shall be issued in the name of the Holder or in such name or names as may be directed by the Holder; provided, however, that in the event that Warrant Shares are to be issued in a name other than the
name of the Holder, this Warrant when surrendered for exercise shall be accompanied by the Assignment Form attached hereto duly executed by the Holder and the Company may require, as a condition thereto, the payment of a sum sufficient to reimburse
it for any transfer tax incidental thereto. The Company shall pay all Transfer Agent fees required for timely processing of any Notice of Exercise and all fees to the Depository Trust Company (or another established clearing corporation performing
similar functions) required for timely electronic delivery of the Warrant Shares. 
 vii. Closing of Books. The
Company will not close its stockholder books or records in any manner which prevents the timely exercise of this Warrant, pursuant to the terms hereof. 

e) Holder’s Exercise Limitations. The Company shall not effect any exercise of this Warrant, and a Holder shall not
have the right to exercise any portion of this Warrant, pursuant to Section 2 or otherwise, to the extent that after giving effect to such issuance after exercise as set forth on the applicable Notice of Exercise, the Holder (together with the
Holder’s Affiliates, and any other Persons acting as a group together with the Holder or any of the Holder’s Affiliates (such Persons, “Attribution Parties”)), would beneficially own in excess of the Beneficial Ownership
Limitation (as defined below). For purposes of the foregoing sentence, the number of shares of Common Stock beneficially owned by the Holder and its Affiliates and Attribution Parties shall include the number of shares of Common Stock issuable
upon exercise of this Warrant with respect to which such determination is being made, but shall exclude the number of shares of Common Stock which would be issuable upon (i) exercise of the remaining, nonexercised portion of this Warrant
beneficially owned by the Holder or any of its Affiliates or Attribution Parties and (ii) exercise or conversion of the unexercised or nonconverted portion of any other securities of the Company (including, without


  
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limitation, any other Common Stock Equivalents) subject to a limitation on conversion or exercise analogous to the limitation contained herein beneficially owned by the Holder or any of its
Affiliates or Attribution Parties. Except as set forth in the preceding sentence, for purposes of this Section 2(e), beneficial ownership shall be calculated in accordance with Section 13(d) of the Exchange Act and the rules and
regulations promulgated thereunder, it being acknowledged by the Holder that the Company is not representing to the Holder that such calculation is in compliance with Section 13(d) of the Exchange Act and the Holder is solely responsible for
any schedules required to be filed in accordance therewith. To the extent that the limitation contained in this Section 2(e) applies, the determination of whether this Warrant is exercisable (in relation to other securities owned by the Holder
together with any Affiliates and Attribution Parties) and of which portion of this Warrant is exercisable shall be in the sole discretion of the Holder, and the submission of a Notice of Exercise shall be deemed to be the Holder’s determination
of whether this Warrant is exercisable (in relation to other securities owned by the Holder together with any Affiliates and Attribution Parties) and of which portion of this Warrant is exercisable, in each case subject to the Beneficial Ownership
Limitation, and the Company shall have no obligation to verify or confirm the accuracy of such determination and will have no liability for exercises of this Warrant that are in non-compliance with the Beneficial Ownership Limitation. In addition, a
determination as to any group status as contemplated above shall be determined in accordance with Section 13(d) of the Exchange Act and the rules and regulations promulgated thereunder. For purposes of this Section 2(e), in determining the
number of outstanding shares of Common Stock, a Holder may rely on the number of outstanding shares of Common Stock as reflected in (A) the Company’s most recent periodic or annual report filed with the Commission, as the case may be,
(B) a more recent public announcement by the Company or (C) a more recent written notice by the Company or the Transfer Agent setting forth the number of shares of Common Stock outstanding. Upon the written or oral request of a
Holder, the Company shall within two Trading Days confirm orally and in writing to the Holder the number of shares of Common Stock then outstanding. In any case, the number of outstanding shares of Common Stock shall be determined after giving
effect to the conversion or exercise of securities of the Company, including this Warrant, by the Holder or its Affiliates or Attribution Parties since the date as of which such number of outstanding shares of Common Stock was reported. The
“Beneficial Ownership Limitation” shall be 4.99% of the number of shares of Common Stock outstanding immediately after giving effect to the issuance of shares of Common Stock issuable upon exercise of this Warrant. The Holder, upon
notice to the Company, may increase or decrease the Beneficial Ownership Limitation provisions of this Section 2(e), provided that the Beneficial Ownership Limitation in no event exceeds 9.99% of the number of shares of Common Stock outstanding
immediately after giving effect to the issuance of shares of Common Stock upon exercise of this Warrant held by the Holder and the provisions of this Section 2(e) shall continue to apply. Any increase in the Beneficial Ownership Limitation will
not be effective until the 61st day after such notice is delivered to the Company and shall only be effective with regard to such Holder. The provisions of this paragraph shall be construed and
implemented in a manner otherwise than in strict conformity with the terms of this Section 2(e) to correct this paragraph (or any portion hereof) which may be defective or inconsistent with the intended Beneficial Ownership Limitation herein
contained or to make changes or supplements necessary or desirable to properly give effect to such limitation. The limitations contained in this paragraph shall apply to any successor holder of this Warrant. 

  
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 Section 3. Certain Adjustments. 

a) Stock Dividends and Splits. If the Company, at any time while this Warrant is outstanding: (i) pays a stock
dividend or otherwise makes a distribution or distributions on shares of its Common Stock or any other equity or equity equivalent securities payable in shares of Common Stock (which, for avoidance of doubt, shall not include any shares of Common
Stock issued by the Company upon exercise of this Warrant), (ii) subdivides outstanding shares of Common Stock into a larger number of shares, (iii) combines (including by way of reverse stock split) outstanding shares of Common Stock into
a smaller number of shares, or (iv) issues by reclassification of shares of the Common Stock any shares of capital stock of the Company, then in each case the Exercise Price shall be multiplied by a fraction of which the numerator shall be the
number of shares of Common Stock (excluding treasury shares, if any) outstanding immediately before such event and of which the denominator shall be the number of shares of Common Stock outstanding immediately after such event, and the number of
shares issuable upon exercise of this Warrant shall be proportionately adjusted such that the aggregate Exercise Price of this Warrant shall remain unchanged. Any adjustment made pursuant to this Section 3(a) shall become effective immediately
after the record date for the determination of stockholders entitled to receive such dividend or distribution and shall become effective immediately after the effective date in the case of a subdivision, combination or
re-classification. 
 b) [RESERVED] 

c) Subsequent Rights Offerings. In addition to any adjustments pursuant to Section 3(a) above, if at any time the
Company grants, issues or sells any Common Stock Equivalents or rights to purchase stock, warrants, securities or other property pro rata to the record holders of any class of shares of Common Stock (the “Purchase Rights”), then the
Holder will be entitled to acquire, upon the terms applicable to such Purchase Rights, the aggregate Purchase Rights which the Holder could have acquired if the Holder had held the number of shares of Common Stock acquirable upon complete exercise
of this Warrant (without regard to any limitations on exercise hereof, including without limitation, the Beneficial Ownership Limitation) immediately before the date on which a record is taken for the grant, issuance or sale of such Purchase Rights,
or, if no such record is taken, the date as of which the record holders of shares of Common Stock are to be determined for the grant, issue or sale of such Purchase Rights (provided, however, to the extent that the Holder’s right to participate
in any such Purchase Right would result in the Holder exceeding the Beneficial Ownership Limitation, then the Holder shall not be entitled to participate in such Purchase Right to such extent (or beneficial ownership of such shares of Common Stock
as a result of such Purchase Right to such extent) and such Purchase Right to such extent shall be held in abeyance for the Holder until such time, if ever, as its right thereto would not result in the Holder exceeding the Beneficial Ownership
Limitation). 

  
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 d) Pro Rata Distributions. During such time as this Warrant is
outstanding, if the Company shall declare or make any dividend or other distribution of its assets (or rights to acquire its assets) to holders of shares of Common Stock, by way of return of capital or otherwise (including, without limitation, any
distribution of cash, stock or other securities, property or options by way of a dividend, spin off, reclassification, corporate rearrangement, scheme of arrangement or other similar transaction) (a “Distribution”), at any time
after the issuance of this Warrant, then, in each such case, the Holder shall be entitled following partial or complete exercise of this Warrant to participate in such Distribution to the same extent that the Holder would have participated therein
if the Holder had held the number of shares of Common Stock acquirable upon such partial or complete exercise of this Warrant, as applicable (without regard to any limitations on exercise hereof, including without limitation, the Beneficial
Ownership Limitation) immediately before the date of which a record is taken for such Distribution, or, if no such record is taken, the date as of which the record holders of shares of Common Stock are to be determined for the participation in such
Distribution (provided, however, to the extent that the Holder’s right to participate in any such Distribution would result in the Holder exceeding the Beneficial Ownership Limitation, then the Holder shall not be entitled to
participate in such Distribution to such extent (or in the beneficial ownership of any shares of Common Stock as a result of such Distribution to such extent) and the portion of such Distribution shall be held in abeyance for the benefit of the
Holder until such time, if ever, as its right thereto would not result in the Holder exceeding the Beneficial Ownership Limitation). To the extent that this Warrant has not been partially or completely exercised at the time of such Distribution,
such portion of the Distribution shall be held in abeyance for the benefit of the Holder until the Holder has exercised this Warrant. 

e) Fundamental Transaction. If, at any time while this Warrant is outstanding, (i) the Company, directly or
indirectly, in one or more related transactions effects any merger or consolidation of the Company with or into another Person (other than for the purpose of changing the name of the Company or changing the Company’s jurisdiction of
incorporation to another state within the United States), (ii) the Company, directly or indirectly, effects any sale, lease, license, assignment, transfer, conveyance or other disposition of all or substantially all of its assets in one or a
series of related transactions, (iii) any, direct or indirect, purchase offer, tender offer or exchange offer (whether by the Company or another Person) is completed pursuant to which holders of Common Stock are permitted to sell, tender or
exchange their shares for other securities, cash or property and has been accepted by the holders of 50% or more of the outstanding Common Stock, (iv) the Company, directly or indirectly, in one or more related transactions effects any
reclassification, reorganization or recapitalization of the Common Stock or any compulsory share exchange pursuant to which the Common Stock is effectively converted into or exchanged for other securities, cash or property, or (v) the Company,
directly or indirectly, in one or more related transactions consummates a stock or share purchase agreement or other business combination (including, without limitation, a reorganization, recapitalization, spin-off or scheme of arrangement) with
another Person or group of Persons whereby such other Person or group acquires more than 50% of the outstanding shares of Common Stock (not including any shares of Common Stock held by the other Person or other Persons making or party to, or
associated or affiliated 

  
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with the other Persons making or party to, such stock or share purchase agreement or other business combination) (each a “Fundamental Transaction”), then, upon any subsequent
exercise of this Warrant, the Holder shall have the right to receive, for each Warrant Share that would have been issuable upon such exercise immediately prior to the occurrence of such Fundamental Transaction, at the option of the Holder (without
regard to any limitation in Section 2(e) on the exercise of this Warrant), the number of shares of Common Stock of the successor or acquiring corporation or of the Company, if it is the surviving corporation, and any additional consideration
(the “Alternate Consideration”) receivable as a result of such Fundamental Transaction by a holder of the number of shares of Common Stock for which this Warrant is exercisable immediately prior to such Fundamental Transaction
(without regard to any limitation in Section 2(e) on the exercise of this Warrant). For purposes of any such exercise, the determination of the Exercise Price shall be appropriately adjusted to apply to such Alternate Consideration based on the
amount of Alternate Consideration issuable in respect of one share of Common Stock in such Fundamental Transaction, and the Company shall apportion the Exercise Price among the Alternate Consideration in a reasonable manner reflecting the relative
value of any different components of the Alternate Consideration. If holders of Common Stock are given any choice as to the securities, cash or property to be received in a Fundamental Transaction, then the Holder shall be given the same choice as
to the Alternate Consideration it receives upon any exercise of this Warrant following such Fundamental Transaction. The Company shall cause any successor entity in a Fundamental Transaction in which the Company is not the survivor (the
“Successor Entity”) to assume in writing all of the obligations of the Company under this Warrant in accordance with the provisions of this Section 3(e) pursuant to written agreements in form and substance reasonably
satisfactory to the Holder and approved by the Holder (without unreasonable delay) prior to such Fundamental Transaction and shall, at the option of the Holder, deliver to the Holder in exchange for this Warrant a security of the Successor Entity
evidenced by a written instrument substantially similar in form and substance to this Warrant which is exercisable for a corresponding number of shares of capital stock of such Successor Entity (or its parent entity) equivalent to the shares of
Common Stock acquirable and receivable upon exercise of this Warrant (without regard to any limitations on the exercise of this Warrant) prior to such Fundamental Transaction, and with an exercise price which applies the exercise price hereunder to
such shares of capital stock (but taking into account the relative value of the shares of Common Stock pursuant to such Fundamental Transaction and the value of such shares of capital stock, such number of shares of capital stock and such exercise
price being for the purpose of protecting the economic value of this Warrant immediately prior to the consummation of such Fundamental Transaction), and which is reasonably satisfactory in form and substance to the Holder. Upon the occurrence of any
such Fundamental Transaction, the Successor Entity shall succeed to, and be substituted for (so that from and after the date of such Fundamental Transaction, the provisions of this Warrant referring to the “Company” shall refer instead to
the Successor Entity), and may exercise every right and power of the Company and shall assume all of the obligations of the Company under this Warrant with the same effect as if such Successor Entity had been named as the Company herein. 

  
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 f) Calculations. All calculations under this Section 3 shall be made
to the nearest cent or the nearest 1/100th of a share, as the case may be. For purposes of this Section 3, the number of shares of Common Stock deemed to be issued and outstanding as of a given date shall be the sum of the number of shares of
Common Stock (excluding treasury shares, if any) issued and outstanding. 
 g) Notice to Holder. 

i. Adjustment to Exercise Price. Whenever the Exercise Price is adjusted pursuant to any provision of this
Section 3, the Company shall promptly deliver to the Holder by facsimile, email or mail a notice setting forth the Exercise Price after such adjustment and any resulting adjustment to the number of Warrant Shares and setting forth a brief
statement of the facts requiring such adjustment. 
 ii. Notice to Allow Exercise by Holder. If, during the term in
which this Warrant is exercisable by the Holder, (A) the Company shall declare a dividend (or any other distribution in whatever form) on the Common Stock, (B) the Company shall declare a special nonrecurring cash dividend on or a
redemption of the Common Stock, (C) the Company shall authorize the granting to all holders of the Common Stock rights or warrants to subscribe for or purchase any shares of capital stock of any class or of any rights, (D) the approval of
any stockholders of the Company shall be required in connection with any reclassification of the Common Stock, any consolidation or merger to which the Company is a party, any sale or transfer of all or substantially all of the assets of the
Company, or any compulsory share exchange whereby the Common Stock is converted into other securities, cash or property, or (E) the Company shall authorize the voluntary or involuntary dissolution, liquidation or winding up of the affairs of
the Company, then, in each case, the Company shall cause to be delivered by facsimile, email or mail to the Holder at its last facsimile number or email or mailing address as it shall appear upon the Warrant Register of the Warrant Agent, at least
10 calendar days prior to the applicable record or effective date hereinafter specified, a notice stating (x) the date on which a record is to be taken for the purpose of such dividend, distribution, redemption, rights or warrants, or if a
record is not to be taken, the date as of which the holders of the Common Stock of record to be entitled to such dividend, distributions, redemption, rights or warrants are to be determined or (y) the date on which such reclassification,
consolidation, merger, sale, transfer or share exchange is expected to become effective or close, and the date as of which it is expected that holders of the Common Stock of record shall be entitled to exchange their shares of the Common Stock for
securities, cash or other property deliverable upon such reclassification, consolidation, merger, sale, transfer or share exchange; provided that the failure to deliver such notice or any defect therein or in the delivery thereof shall not affect
the validity of the corporate action required to be specified in such notice. To the extent that any notice provided in this Warrant constitutes, or contains, material, non-public information regarding the Company or any of the


  
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Subsidiaries, the Company shall simultaneously file such notice with the Commission pursuant to a Current Report on Form 8-K. The Holder shall remain entitled to exercise this Warrant during the
period commencing on the date of such notice to the effective date of the event triggering such notice except as may otherwise be expressly set forth herein. 

Section 4. Transfer of Warrant. 

a) Transferability. Subject to compliance with applicable securities laws, the Holder may transfer this Warrant and all
rights hereunder (including, without limitation, any registration rights), in whole or in part, upon surrender of this Warrant to the Warrant Agent or DTC, as applicable, together with (i) a written assignment of this Warrant substantially in
the form attached hereto duly executed by the Holder or its agent or attorney, and (ii) funds sufficient to pay any transfer taxes payable upon the making of such transfer. Upon such surrender and, if required, such payment, the Warrant Agent
shall execute and deliver a new Warrant or Warrants in the name of the assignee or assignees, as applicable, and in the denomination or denominations specified in such instrument of assignment, and shall issue to the assignor a new Warrant
evidencing the portion of this Warrant not so assigned, and this Warrant shall promptly be cancelled. Notwithstanding anything herein to the contrary, the Holder shall not be required to physically surrender this Warrant to the Warrant Agent unless
the Holder has assigned this Warrant in full, in which case, the Holder shall surrender this Warrant to the Warrant Agent within three (3) Trading Days of the date the Holder delivers an assignment form to the Warrant Agent assigning this
Warrant full. The Warrant, if properly assigned in accordance herewith, may be exercised by a new holder for the purchase of Warrant Shares without having a new Warrant issued. 

A Holder requesting transfer of this Warrant must provide any evidence of authority that may be required by the Warrant Agent,
including but not limited to, a signature guarantee from an eligible guarantor institution participating in a signature guarantee program approved by the Securities Transfer Association. 

b) New Warrants. This Warrant may be divided or combined with other Warrants upon presentation hereof to the Warrant
Agent or DTC, as applicable, together with a written notice specifying the names and denominations in which new Warrants are to be issued, signed by the Holder or its agent or attorney. Subject to compliance with Section 4(a), as to any
transfer which may be involved in such division or combination, the Warrant Agent shall execute and deliver a new Warrant or Warrants in exchange for the Warrant or Warrants to be divided or combined in accordance with such notice. All Warrants
issued on transfers or exchanges shall be dated the initial issuance date of this Warrant and shall be identical with this Warrant except as to the number of Warrant Shares issuable pursuant thereto. 

c) Warrant Register. The Warrant Agent shall register this Warrant, upon records to be maintained by the Warrant Agent
for that purpose (the “Warrant Register”), in the name of the record Holder hereof from time to time. The Warrant Agent 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, absent actual notice to the contrary. 

  
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 Section 5. Miscellaneous. 

a) No Rights as Stockholder Until Exercise. This Warrant does not entitle the Holder to any voting rights, dividends or
other rights as a stockholder of the Company prior to the exercise hereof as set forth in Section 2(d)(i), except as expressly set forth in Section 3. 

b) Loss, Theft, Destruction or Mutilation of Warrant. The Company covenants that upon receipt by the Company of evidence
reasonably satisfactory to it of the loss, theft, destruction or mutilation of this Warrant or any stock certificate relating to the Warrant Shares, and in case of loss, theft or destruction, of indemnity or security reasonably satisfactory to it,
and upon surrender and cancellation of such Warrant or stock certificate, if mutilated, the Company will make and deliver, or cause the Warrant Agent to make and deliver, a new Warrant or stock certificate of like tenor and dated as of such
cancellation, in lieu of such Warrant or stock certificate. 
 c) Saturdays, Sundays, Holidays, etc. If the last or
appointed day for the taking of any action or the expiration of any right required or granted herein shall not be a Business Day, then, such action may be taken or such right may be exercised on the next succeeding Business Day. 

d) Authorized Shares. The Company covenants that, during the period the Warrant is outstanding, it will reserve from its
authorized and unissued Common Stock a sufficient number of shares to provide for the issuance of the Warrant Shares upon the exercise of any purchase rights under this Warrant. The Company further covenants that its issuance of this Warrant shall
constitute full authority to its officers and agent who are charged with the duty of issuing the necessary Warrant Shares upon the exercise of the purchase rights under this Warrant. The Company will take all such reasonable action as may be
necessary to assure that such Warrant Shares may be issued as provided herein without violation of any applicable law or regulation, or of any requirements of the Trading Market upon which the Common Stock may be listed. The Company covenants that
all Warrant Shares which may be issued upon the exercise of the purchase rights represented by this Warrant will, upon exercise of the purchase rights represented by this Warrant and payment for such Warrant Shares in accordance herewith, be duly
authorized, validly issued, fully paid and nonassessable and free from all taxes, liens and charges created by the Company in respect of the issue thereof (other than taxes in respect of any transfer occurring contemporaneously with such issue) 

Except and to the extent as waived or consented to by the Holder, the Company shall not by any action, including, without
limitation, amending its certificate of incorporation 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 

  
 13 








 
actions as may be necessary or appropriate to protect the rights of Holder as set forth in this Warrant against impairment. Without limiting the generality of the foregoing, the Company will
(i) not increase the par value of any Warrant Shares above the amount payable therefor upon such exercise immediately prior to such increase in par value, (ii) take all such action as may be necessary or appropriate in order that the
Company may validly and legally issue fully paid and nonassessable Warrant Shares upon the exercise of this Warrant and (iii) use commercially reasonable efforts to obtain all such authorizations, exemptions or consents from any public
regulatory body having jurisdiction thereof, as may be, necessary to enable the Company to perform its obligations under this Warrant. 

Before taking any action which would result in an adjustment in the number of Warrant Shares for which this Warrant is
exercisable or in the Exercise Price, the Company shall obtain all such authorizations or exemptions thereof, or consents thereto, as may be necessary from any public regulatory body or bodies having jurisdiction thereof. 

e) Jurisdiction. All questions concerning the construction, validity, enforcement and interpretation of this Warrant
shall be governed by and construed and enforced in accordance with the internal laws of the State of New York, without regard to the principles of conflicts of law thereof. Each party agrees that all legal proceedings concerning the interpretations,
enforcement and defense of the transactions contemplated by this Warrant (whether brought against a party hereto or their respective affiliates, directors, officers, shareholders, partners, members, employees or agents) shall be commenced
exclusively in the state and federal courts sitting in the City of New York. Each party hereby irrevocably submits to the exclusive jurisdiction of the state and federal courts sitting in the City of New York, Borough of Manhattan 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, any claim that it is not
personally subject to the jurisdiction of any such court, that such suit, action or proceeding is improper or is an inconvenient venue for such proceeding. Each party hereby irrevocably waives, to the fullest extent permitted by applicable law, any
and all right to trial by jury in any legal proceeding arising out of or relating to this Warrant and any 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 other manner permitted by law. If either party shall commence an action, suit or proceeding to enforce any provisions of this Warrant, the
prevailing party in such action, suit or proceeding shall be reimbursed by the other party for their reasonable attorneys’ fees and other costs and expenses incurred with the investigation, preparation and prosecution of such action or
proceeding. 
 f) Restrictions. The Holder acknowledges that the Warrant Shares acquired upon the exercise of this
Warrant, if not registered, and the Holder does not utilize cashless exercise, will have restrictions upon resale imposed by state and federal securities laws. 

  
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 g) Nonwaiver and Expenses. No course of dealing or any delay or failure to
exercise any right hereunder on the part of Holder shall operate as a waiver of such right or otherwise prejudice the Holder’s rights, powers or remedies. Without limiting any other provision of this Warrant, if a party willfully and knowingly
fails to comply with any provision of this Warrant, which results in any material damages to the other party, the offending party shall pay to the other party such amounts as shall be sufficient to cover any costs and expenses including, but not
limited to, reasonable attorneys’ fees, including those of appellate proceedings, incurred by such other party in collecting any amounts due pursuant hereto or in otherwise enforcing any of its rights, powers or remedies hereunder. 

h) Notices. Any notices, consents, waivers or other document or communications required or permitted to be given or
delivered under the terms of this Warrant must be in writing and will be deemed to have been delivered: (i) upon receipt, if delivered personally; (ii) when sent, if sent by facsimile (provided confirmation of transmission is mechanically
or electronically generated and kept on file by the sending party); (iii) when sent, if sent by e-mail (provided that such sent e-mail is kept on file (whether electronically or otherwise) by the sending party and the sending party does not
receive an automatically generated message from the recipient’s e-mail server that such e-mail could not be delivered to such recipient) and (iv) if sent by overnight courier service, one (1) Trading Day after deposit with an
overnight courier service with next day delivery specified, in each case, properly addressed to the party to receive the same. If notice is given by facsimile or email, a copy of such notice shall be dispatched no later than the next Business Day by
first class mail, postage prepaid. The addresses, facsimile numbers and e-mail addresses for such communications shall be: 

If to the Company: 

RXi Pharmaceuticals Corporation 

257 Simarano Drive, Suite 210 

Marlborough, MA 01752 

Facsimile: 508-303-3400 

Attention: Finance Department 

ckontulis@rxipharma.com 

If to the Warrant Agent: 

Computershare Inc. 

250 Royall Street 

Canton, MA 02021 

  
 15 








 If to a Holder, to its address, facsimile number or e-mail address set forth herein or on the
books and records of the Company, the Transfer Agent or the Warrant Agent. 
 i) Or, in each of the above instances, to such
other address, facsimile number or e-mail address and/or to the attention of such other Person as the recipient party has specified by written notice given to each other party at least five (5) days prior to the effectiveness of such change.
Written confirmation of receipt (A) given by the recipient of such notice, consent, waiver or other communication, (B) mechanically or electronically generated by the sender’s facsimile machine containing the time, date and recipient
facsimile number or (C) provided by an overnight courier service shall be rebuttable evidence of personal service, receipt by facsimile or receipt from an overnight courier service in accordance with clause (i), (ii) or (iv) above,
respectively. A copy of the e-mail transmission containing the time, date and recipient e- mail address shall be rebuttable evidence of receipt by e-mail in accordance with clause (iii) above. 

j) Limitation of Liability. No provision hereof, in the absence of any affirmative action by the Holder to exercise this
Warrant to purchase Warrant Shares, and no enumeration herein of the rights or privileges of the Holder, shall give rise to any liability of the Holder for the purchase price of any Common Stock or as a stockholder of the Company, whether such
liability is asserted by the Company or by creditors of the Company. 
 k) Remedies. The Holder, in addition to being
entitled to exercise all rights granted by law, including recovery of damages, will be entitled to specific performance of its rights under this Warrant. The Company agrees that monetary damages would not be adequate compensation for any loss
incurred by reason of a breach by it of the provisions of this Warrant and hereby agrees to waive and not to assert the defense in any action for specific performance that a remedy at law would be adequate. 

l) Successors and Assigns. Subject to applicable securities laws, this Warrant and the rights and obligations evidenced
hereby shall inure to the benefit of and be binding upon the successors and permitted assigns of the Company and the successors and permitted assigns of Holder. The provisions of this Warrant are intended to be for the benefit of any Holder from
time to time of this Warrant and shall be enforceable by the Holder or holder of Warrant Shares. 
 m) Amendment. This
Warrant may be modified or amended or the provisions hereof waived with the written consent of the Company and the Holder. 

n) Severability. Wherever possible, each provision of this Warrant shall be interpreted in such manner as to be
effective and valid under applicable law, but if any provision of this Warrant shall be prohibited by or invalid under applicable law, such provision shall be ineffective to the extent of such prohibition or invalidity, without invalidating the
remainder of such provisions or the remaining provisions of this Warrant. 
 o) Headings. The headings used in this
Warrant are for the convenience of reference only and shall not, for any purpose, be deemed a part of this Warrant. 

  
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 p) Counterparts. A signature to this Warrant transmitted electronically
shall have the same authority, effect and enforceability as an original signature. 
 q) Beneficial Owner. A
beneficial owner of this Warrant has the right, upon written notice by such beneficial owner to the Warrant Agent, to request the exchange of some or all of such beneficial owner’s Warrants (the “Global Warrant(s)”) represented
by one or more global warrants on deposit with Cede & Co. (or its successor) for a physical warrant certificate in the form hereof (a “Warrant Certificate Request Notice” and the date of delivery of such Warrant Certificate
Request Notice by the Holder, the “Warrant Certificate Request Notice Date” and the deemed surrender upon delivery by the Holder of a number of Global Warrants for the same number of Warrants and Warrant Shares evidenced by a
Warrant Certificate, a “Warrant Exchange”, and such physical certificate, a “Warrant Certificate”). Upon delivery of a Warrant Certificate Request Notice, the Warrant Agent shall promptly effect the Warrant Exchange
and shall promptly issue and deliver to the beneficial owner a physical Warrant Certificate for such number of Warrants in the name set forth in the Warrant Certificate Request Notice. Such Warrant Certificate shall be dated the original issue date
of the Warrants and shall be executed by an authorized signatory of the Company. In connection with a Warrant Exchange, the Company agrees to deliver, or to direct the Warrant Agent to deliver, the Warrant Certificate to the Holder within three
(3) Business Days of the delivery of a properly completed and executed Warrant Certificate Request Notice pursuant to the delivery instructions in the Warrant Certificate Request Notice. The Company covenants and agrees that, upon the date of
delivery of the properly completed and executed Warrant Certificate Request Notice, the Holder shall be deemed to be the holder of the Warrant Certificate and, notwithstanding anything to the contrary set forth herein, the Warrant Certificate shall
be deemed for all purposes to contain all of the terms and conditions of the Warrants evidenced by such Warrant Certificate. 

******************** 

(Signature Page Follows) 

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

					
	RXi PHARMACEUTICALS CORPORATION
		
	By:	 	 
		 	 Name:
	 	
		 	 Title:
	 	



  
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 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 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: 
  

                     
                                     

 
  

                     
                                     

 
  

                     
                                     

 
 [SIGNATURE OF HOLDER] 

 

			
	Name of Investing Entity:    	  	 
	Signature of Authorized Signatory of Investing Entity:	  	 
	Name of Authorized Signatory:	  	 
	Title of Authorized Signatory:	  	 
	Date:	  	 


  
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 EXHIBIT B 

ASSIGNMENT FORM 
 (To assign
the foregoing Warrant, execute this form and supply required information. Do not use this form to purchase shares.) 
 FOR VALUE RECEIVED, the foregoing
Warrant and all rights evidenced thereby are hereby assigned to 
  

			
	Name:	  	
		  	  

		  	(Please Print)
		
	Address:	  	
		  	  

		  	(Please Print)
		
	Phone Number:	  	
		  	  

		
	Email Address:	  	
		  	  

		
	Dated:                             
        ,             	  	
		
	Holder’s
Signature:                                       
                   	  	
		
	Holder’s
Address:                                       
                     	  	


  
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