Document:

Exhibit 4.2

 Exhibit 4.2 

[FORM OF WARRANT] 

ALTIMMUNE, INC. 

WARRANT TO PURCHASE COMMON STOCK 

Warrant No.:
                            

Number of Shares of Common Stock:
                           

Date of Issuance: October 10, 2018 (“Issuance Date”) 

Altimmune, Inc., a Delaware corporation (the “Company”), hereby certifies that, for good and valuable consideration, the
receipt and sufficiency of which are hereby acknowledged, [HOLDER], the registered holder hereof or its permitted assigns (the “Holder”), is entitled, subject to the terms set forth below, to purchase from the Company, at the
Exercise Price (as defined below) then in effect, at any time or times on or after October 10, 2018 (the “Initial Exercisability Date”), but not after 11:59 p.m., New York time, on the Expiration Date, (as defined below),
                     (                    )1 fully paid non-assessable shares of Common Stock (as defined below), subject to adjustment as provided herein (the “Warrant Shares”).
Except as otherwise defined herein, capitalized terms in this Warrant to Purchase Common Stock (including any Warrants to Purchase Common Stock issued in exchange, transfer or replacement hereof, this “Warrant”), shall have the
meanings set forth in Section 16. This Warrant is one of the Warrants to Purchase Common Stock (the “Warrants”) issued pursuant to (i) that certain Securities Purchase Agreement, dated as of October 8, 2018 (the
“Subscription Date”) by and between the Company and investors party thereto, (ii) the Company’s Registration Statement on Form S-3 (File number
333-217034 (the “Registration Statement”) and (iii) the Company’s prospectus supplement, dated as of October 8, 2018, and the related base prospectus, dated March 30, 2017
(collectively, the “Prospectus”). 
 1. EXERCISE OF WARRANT. 

(a) Mechanics of Exercise. Subject to the terms and conditions hereof (including, without limitation, the limitations set forth in
Section 1(f)), this Warrant may be exercised by the Holder at any time or times on or after the Initial Exercisability Date, in whole or in part, by delivery (whether via facsimile, electronic mail or otherwise) of a written notice, in the form
attached hereto as Exhibit A (the “Exercise Notice”), of the Holder’s election to exercise this Warrant. Within one (1) Trading Day following the delivery of the Exercise Notice, the Holder shall make payment to the
Company of an amount equal to the Exercise Price in effect on the date of such exercise multiplied by the number of Warrant Shares as to which this Warrant is being exercised (the “Aggregate Exercise Price”) in cash by wire transfer
of immediately available funds or, if the provisions of Section 1(d) are applicable, by notifying the 
  

	1 	 Insert 100% of the number of shares of Common Stock purchased.

 
Company that this Warrant is being exercised pursuant to a Cashless Exercise (as defined in Section 1(d)). The Holder shall not be required to deliver the original Warrant in order to effect
an exercise hereunder (until the Holder has purchased all of the Warrant Shares available hereunder and the Warrant has been exercised in full), nor shall any ink-original signature or medallion guarantee (or
other type of guarantee or notarization) with respect to any Exercise Notice be required. Execution and delivery of the Exercise Notice with respect to less than all of the Warrant Shares shall have the same effect as cancellation of the original
Warrant and issuance of a new Warrant evidencing the right to purchase the remaining number of Warrant Shares and the Holder shall not be required to physically surrender this Warrant to the Company 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 Company for cancellation within three (3) Trading Days of the date on which the final Notice of Exercise is
delivered to the Company. On or before the first (1st) Trading Day following the date on which the Holder has delivered the applicable Exercise Notice, the Company shall transmit by facsimile or
electronic mail an acknowledgment of confirmation of receipt of the Exercise Notice, in the form attached to the Exercise Notice, to the Holder and the Company’s transfer agent (the “Transfer Agent”). So long as the Holder
delivers the Aggregate Exercise Price (or notice of a Cashless Exercise, if applicable) on or prior to the first (1st) Trading Day following the date on which the Exercise Notice has been
delivered to the Company, then on or prior to the earlier of (i) the second (2nd) Trading Day and (ii) the number of Trading Days comprising the Standard Settlement Period, in each case
following the date on which the Exercise Notice has been delivered to the Company, or, if the Holder does not deliver the Aggregate Exercise Price (or notice of a Cashless Exercise, if applicable) on or prior to the first (1st) Trading Day following the date on which the Exercise Notice has been delivered to the Company, then on or prior to the first (1st) Trading Day
following the date on which the Aggregate Exercise Price (or notice of a Cashless Exercise, if applicable) is delivered (such earlier date, or if later, the earliest day on which the Company is required to deliver Warrant Shares pursuant to this
Section 1(a), the “Share Delivery Date”), the Company shall (X) provided that the Transfer Agent is participating in The Depository Trust Company (“DTC”) Fast Automated Securities Transfer Program, credit
such aggregate number of Warrant Shares to which the Holder is entitled pursuant to such exercise to the Holder’s or its designee’s balance account with DTC through its Deposit / Withdrawal At Custodian system, or (Y) if the Transfer
Agent is not participating in the DTC Fast Automated Securities Transfer Program, issue and dispatch by overnight courier to the address as specified in the Exercise Notice, a certificate, registered 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. The Company shall be responsible for all fees and expenses of the Transfer Agent and all fees and expenses with respect to the issuance of Warrant Shares via
DTC, if any, including without limitation for same day processing. Upon delivery of the Exercise Notice, the Holder shall be deemed for all corporate purposes to have become the holder of record and beneficial owner of the Warrant Shares with
respect to which this Warrant has been exercised, irrespective of the date such Warrant Shares are credited to the Holder’s DTC account or the date of delivery of the certificates evidencing such Warrant Shares, as the case may be. If this
Warrant is physically delivered to the Company in connection with any exercise pursuant to this Section 1(a) and the number of Warrant Shares represented by this Warrant submitted for exercise is greater than the number of Warrant Shares being
acquired upon an exercise, then the Company shall as soon as practicable and in no event later than three (3) Trading Days after any exercise 

  
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and at its own expense, issue and deliver to the Holder (or its designee) a new Warrant (in accordance with Section 7(d)) representing the right to purchase the number of Warrant Shares
issuable immediately prior to such exercise under this Warrant, less the number of Warrant Shares with respect to which this Warrant is exercised. No fractional Warrant Shares are to be issued upon the exercise of this Warrant, but rather the number
of Warrant Shares to be issued shall be rounded to the nearest whole number. The Company shall pay any and all transfer, stamp, issuance and similar taxes, costs and expenses (including, without limitation, fees and expenses of the Transfer Agent)
which may be payable with respect to the issuance and delivery of Warrant Shares upon exercise of this Warrant. The Company’s obligations to issue and deliver Warrant Shares in accordance with the terms and subject to the conditions hereof are
absolute and unconditional, irrespective of any action or inaction by the Holder to enforce the same, any waiver or consent with respect to any provision hereof, the recovery of any judgment against any Person or any action to enforce the same, or
any setoff, counterclaim, recoupment, limitation or termination; provided, however, that the Company shall not be required to deliver Warrant Shares with respect to an exercise prior to the Holder’s delivery of the Aggregate
Exercise Price (or notice of a Cashless Exercise, if applicable) with respect to such exercise. 
 (b) Exercise Price. For purposes
of this Warrant, “Exercise Price” means $[5.40] per share, subject to adjustment as provided herein. 
 (c)
Company’s Failure to Timely Deliver Securities. If the Company fails for any reason to deliver to the Holder the Warrant Shares subject to a Notice of Exercise by the Share Delivery Date, 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), $10 per Trading Day (increasing to $20 per Trading Day on
the fifth Trading Day after such liquidated damages begin to accrue) for each Trading Day after such Share Delivery Date until such Warrant Shares are delivered or Holder rescinds such exercise. In addition to any other rights available to the
Holder, if the Company fails to cause the Transfer Agent to transmit to the Holder the Warrant Shares in accordance with the provisions of Section 1(a) above pursuant to an exercise on or before the Share Delivery Date, 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 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 Company 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) or deliver to the Holder the number of shares of Common Stock that would have been issued had the Company 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 

  
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the Holder $1,000. The Holder shall provide the Company written notice indicating the amounts payable to the Holder in respect of the Buy-In and, upon
request of 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 Company’s failure to timely deliver shares of Common Stock upon exercise of the Warrant as required pursuant to the terms hereof. The Company’s current transfer agent participates in the DTC
Fast Automated Securities Transfer Program (“FAST”). In the event that the Company changes transfer agents while this Warrant is outstanding, the Company shall use commercially reasonable efforts to select a transfer agent that
participates in FAST. While this Warrant is outstanding, the Company shall request its transfer agent to participate in FAST with respect to this Warrant. 

(d) Cashless Exercise. Notwithstanding anything contained herein to the contrary, if a registration statement (which may be the
Registration Statement) covering the issuance or resale of the Warrant Shares is not then effective or available for the issuance of such Warrant Shares, 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 Aggregate 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 x B) - (A x 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 average of the Closing Sale Prices of the shares of Common Stock (as reported by Bloomberg Financial Markets) for five consecutive
Trading Days ending on the date immediately preceding the Exercise Date. 
 C= the Exercise Price then in effect for the applicable Warrant
Shares at the time of such exercise. 
 If Warrant Shares are issued in such a cashless exercise, the Company acknowledges and agrees that
in accordance with Section 3(a)(9) of the Securities Act of 1933, as amended, the Warrant Shares shall take on the registered characteristics of the Warrants being exercised, and the holding period of the Warrants being exercised may be tacked
on to the holding period of the Warrant Shares. The Company agrees not to take any position contrary to this Section 1(d). Except as expressly set forth in Section 4(b) herein, nothing in this Warrant shall require the Company to effect
cash settlement of this Warrant. 
 (e) Disputes. In the case of a dispute as to the determination of the Exercise Price or the
arithmetic calculation of the Warrant Shares, the Company shall promptly issue to the Holder the number of Warrant Shares that are not disputed and resolve such dispute in accordance with Section 11. 

  
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 (f) Beneficial Ownership. Notwithstanding anything to the contrary contained herein,
the Company shall not effect the exercise of any portion of this Warrant, and the Holder shall not have the right to exercise any portion of this Warrant, pursuant to the terms and conditions of this Warrant and any such exercise shall be null and
void and treated as if never made, to the extent that after giving effect to such exercise, the Holder together with the other Attribution Parties collectively would beneficially own in excess of [4.99][9.99]% (the “Maximum
Percentage”) of the number of shares of Common Stock outstanding immediately after giving effect to such exercise. For purposes of the foregoing sentence, the aggregate number of shares of Common Stock beneficially owned by the Holder and
the other Attribution Parties shall include the number of shares of Common Stock held by the Holder and all other Attribution Parties plus the number of shares of Common Stock issuable upon exercise of this Warrant with respect to which the
determination of such sentence is being made, but shall exclude the number of shares of Common Stock which would be issuable upon (A) exercise of the remaining, unexercised portion of this Warrant beneficially owned by the Holder or any of the
other Attribution Parties and (B) exercise or conversion of the unexercised or unconverted portion of any other securities of the Company (including, without limitation, any convertible notes or convertible preferred stock or warrants,
including the other Warrants) beneficially owned by the Holder or any other Attribution Party subject to a limitation on conversion or exercise analogous to the limitation contained in this Section 1(f). For purposes of this Section 1(f),
beneficial ownership shall be calculated in accordance with Section 13(d) of the Securities Exchange Act of 1934, as amended (the “1934 Act”), 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 1(f) 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 Company shall have no obligation to verify or confirm the accuracy of such determination.    In addition, a determination as to any group status as contemplated above shall be
determined by the Holder in accordance with Section 13(d) of the Exchange Act and the rules and regulations promulgated thereunder. For purposes of this Warrant, in determining the number of outstanding shares of Common Stock the Holder may
acquire upon the exercise of this Warrant without exceeding the Maximum Percentage, the Holder may rely on the number of outstanding shares of Common Stock as reflected in (x) the Company’s most recent Annual Report on Form 10-K, Quarterly Report on Form 10-Q and Current Reports on Form 8-K or other public filing with the Securities and Exchange Commission
(the “SEC”), as the case may be, (y) a more recent public announcement by the Company or (z) any other written notice by the Company or the Transfer Agent setting forth the number of shares of Common Stock outstanding (the
“Reported Outstanding Share Number”). If the Company receives an Exercise Notice from the Holder at a time when the actual number of outstanding shares of Common Stock is less than the Reported Outstanding Share Number, the Company
shall (i) notify the Holder in writing of the number of shares of Common Stock then outstanding and, to the extent that such Exercise Notice would otherwise cause the Holder’s beneficial ownership, as determined pursuant to this
Section 1(f), to exceed the Maximum Percentage, the Holder must notify the Company of a reduced number of 

  
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Warrant Shares to be purchased pursuant to such Exercise Notice (the number of shares by which such purchase is reduced, the “Reduction Shares”) and (ii) as soon as
reasonably practicable, the Company shall return to the Holder any exercise price paid by the Holder for the Reduction Shares. For any reason at any time, upon the written request of the Holder, the Company shall within two (2) Business Days
confirm orally and in writing or by electronic mail to such 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 and any other Attribution Party since the date as of which the Reported Outstanding Share Number was reported. In the event that the issuance of Common Stock to the Holder
upon exercise of this Warrant results in the Holder and the other Attribution Parties being deemed to beneficially own, in the aggregate, more than the Maximum Percentage of the number of outstanding shares of Common Stock (as determined under
Section 13(d) of the 1934 Act), the number of shares so issued by which the Holder’s and the other Attribution Parties’ aggregate beneficial ownership exceeds the Maximum Percentage (the “Excess Shares”) shall be
deemed null and void and shall be cancelled ab initio, and the Holder shall not have the power to vote or to transfer the Excess Shares. As soon as reasonably practicable after the issuance of the Excess Shares has been deemed null and void, the
Company shall return to the Holder the exercise price paid by the Holder for the Excess Shares. Upon delivery of a written notice to the Company, the Holder may from time to time increase or decrease the Maximum Percentage to any other percentage
not in excess of [4.99][9.99]% as specified in such notice; provided that (i) any such increase in the Maximum Percentage will not be effective until the sixty-first (61st) day after such
notice is delivered to the Company and (ii) any such increase or decrease will apply only to the Holder and the other Attribution Parties and not to any other holder of Warrants that is not an Attribution Party of the Holder. For purposes of
clarity, the shares of Common Stock issuable pursuant to the terms of this Warrant in excess of the Maximum Percentage shall not be deemed to be beneficially owned by the Holder for any purpose including for purposes of Section 13(d) or Rule 16a-1(a)(1) of the 1934 Act. No prior inability to exercise this Warrant pursuant to this paragraph shall have any effect on the applicability of the provisions of this paragraph with respect to any subsequent
determination of exercisability. The provisions of this paragraph shall be construed and implemented in a manner otherwise than in strict conformity with the terms of this Section 1(f) to the extent necessary to correct this paragraph or any
portion of this paragraph which may be defective or inconsistent with the intended beneficial ownership limitation contained in this Section 1(f) or to make changes or supplements necessary or desirable to properly give effect to such
limitation. The limitation contained in this paragraph may not be waived and shall apply to a successor holder of this Warrant. 
 (g)
Required Reserve Amount. So long as this Warrant remains outstanding, the Company shall at all times keep reserved for issuance under this Warrant a number of shares of Common Stock at least equal to 100% of the maximum number of shares
of Common Stock as shall be necessary to satisfy the Company’s obligation to issue shares of Common Stock under the Warrants then outstanding (without regard to any limitations on exercise) (the “Required Reserve Amount”);
provided that at no time shall the number of shares of Common Stock reserved pursuant to this Section 1(g) be reduced other than in connection with any exercise of Warrants or such other event covered by Section 2 below. The
Required Reserve Amount (including, without limitation, each increase in the number of shares so reserved) shall be allocated pro rata among the holders of the Warrants based on the number 

  
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of shares of Common Stock issuable upon exercise of Warrants held by each holder thereof on the Issuance Date (without regard to any limitations on exercise) (the “Authorized Share
Allocation”). In the event that a holder shall sell or otherwise transfer any of such holder’s Warrants, each transferee shall be allocated a pro rata portion of such holder’s Authorized Share Allocation. Any shares of Common
Stock reserved and allocated to any Person which ceases to hold any Warrants shall be allocated to the remaining holders of Warrants, pro rata based on the number of shares of Common Stock issuable upon exercise of the Warrants then held by such
holders thereof (without regard to any limitations on exercise). 
 (h) Insufficient Authorized Shares. If at any time while this
Warrant remains outstanding the Company does not have a sufficient number of authorized and unreserved shares of Common Stock to satisfy its obligation to reserve for issuance the Required Reserve Amount (an “Authorized Share
Failure”), then the Company shall promptly take all action reasonably necessary to increase the Company’s authorized shares of Common Stock to an amount sufficient to allow the Company to reserve the Required Reserve Amount for this
Warrant then outstanding. Without limiting the generality of the foregoing sentence, as soon as practicable after the date of the occurrence of an Authorized Share Failure, but in no event later than ninety (90) days after the occurrence of
such Authorized Share Failure, the Company shall hold a meeting of its stockholders for the approval of an increase in the number of authorized shares of Common Stock. In connection with such meeting, the Company shall provide each stockholder with
a proxy statement and shall use its reasonable best efforts to solicit its stockholders’ approval of such increase in authorized shares of Common Stock and to cause its board of directors to recommend to the stockholders that they approve such
proposal. Notwithstanding the foregoing, if any such time of an Authorized Share Failure, the Company is able to obtain the written consent of a majority of the shares of its issued and outstanding shares of Common Stock to approve the increase in
the number of authorized shares of Common Stock, the Company may satisfy this obligation by obtaining such consent and submitting for filing with the SEC an Information Statement on Schedule 14C. 

2. CERTAIN ADJUSTMENTS. 

(a) [Reserved] 

(b) Stock Dividends and Splits. If the Company at any time on or after the Subscription Date subdivides (by any stock split, stock
dividend, recapitalization or otherwise) one or more classes of its outstanding shares of Common Stock into a greater number of shares, the Exercise Price in effect immediately prior to such subdivision will be proportionately reduced and the number
of Warrant Shares will be proportionately increased. If the Company at any time on or after the Subscription Date combines (by combination, reverse stock split or otherwise) one or more classes of its outstanding shares of Common Stock into a
smaller number of shares, the Exercise Price in effect immediately prior to such combination will be proportionately increased and the number of Warrant Shares will be proportionately decreased. Any adjustment under this Section 2(b) shall
become effective at the close of business on the date the subdivision or combination becomes effective. 

  
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 3. RIGHTS UPON DISTRIBUTION OF ASSETS. In addition to any adjustments pursuant to
Section 2 above, if, on or after the Subscription Date and on or prior to the Expiration Date, 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, options, evidence of indebtedness or any other assets 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 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 complete exercise of this Warrant (without regard to any limitations or restrictions on
exercise of this Warrant, including without limitation, the Maximum Percentage) immediately before the date on 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, that to the extent that the Holder’s right to participate in any such Distribution would result in the Holder and the other Attribution
Parties exceeding the Maximum Percentage, then the Holder shall not be entitled to participate in such Distribution to such extent (and shall not be entitled to beneficial ownership of such shares of Common Stock as a result of such Distribution
(and beneficial ownership) to such extent) and the portion of such Distribution shall be held in abeyance for the benefit of the Holder until such time or times as its right thereto would not result in the Holder and the other Attribution Parties
exceeding the Maximum Percentage, at which time or times the Holder shall be granted such Distribution (and any Distributions declared or made on such initial Distribution or on any subsequent Distribution held similarly in abeyance) to the same
extent as if there had been no such limitation). 
 4. PURCHASE RIGHTS; FUNDAMENTAL TRANSACTIONS. 

(a) Purchase Rights. In addition to any adjustments pursuant to Section 2 above, if at any time on or after the Subscription Date
and on or prior to the Expiration Date the Company grants, issues or sells any Options, Convertible Securities or rights to purchase stock, warrants, securities or other property pro rata to the record holders of any class 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 or restrictions on exercise of this Warrant, including without limitation, the Maximum Percentage) 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 Common Stock are to be determined for the grant, issuance or sale of such Purchase Rights (provided,
however, that to the extent that the Holder’s right to participate in any such Purchase Right would result in the Holder and the other Attribution Parties exceeding the Maximum Percentage, then the Holder shall not be entitled to
participate in such Purchase Right to such extent (and shall not be entitled to beneficial ownership of such Common Stock as a result of such Purchase Right (and beneficial ownership) to such extent) and such Purchase Right to such extent shall be
held in abeyance for the benefit of the Holder until such time or times as its right thereto would not result in the Holder and the other Attribution Parties exceeding the Maximum Percentage, at which time or times the Holder shall be granted such
right (and any Purchase Right granted, issued or sold on such initial Purchase Right or on any subsequent Purchase Right to be held similarly in abeyance) to the same extent as if there had been no such limitation). 

  
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 (b) Fundamental Transaction. The Company shall not enter into or be party to a
Fundamental Transaction unless the Successor Entity assumes in writing all of the obligations of the Company under this Warrant in accordance with the provisions of this Section 4(b), including agreements to 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, including, without limitation, which is exercisable for a corresponding number of shares of capital
stock 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 adjustments
to the 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). Notwithstanding the foregoing, in the
event of an all-cash sale of the Company, at the Company’s option, the Company or the Successor Entity shall have the right to purchase this Warrant from the Holder by paying to the Holder on the
effective date of the Fundamental Transaction, cash in an amount equal to the Black-Scholes Value of the remaining unexercised portion of this Warrant on the date of such Fundamental Transaction. Except in the case of the purchase of this Warrant
pursuant to the terms of the immediately preceding sentence, upon the consummation of each Fundamental Transaction, the Successor Entity shall succeed to, and be substituted for the Company (so that from and after the date of the applicable
Fundamental Transaction, the provisions of this Warrant and the other Transaction Documents 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. Notwithstanding the foregoing, and without limiting Section 1(f) hereof, the Holder may elect, at its
sole option, by delivery of written notice to the Company to waive this Section 4(b) to permit the Fundamental Transaction without the assumption of this Warrant. In addition to and not in substitution for any other rights hereunder, prior to
the consummation of each Fundamental Transaction pursuant to which holders of shares of Common Stock are entitled to receive securities or other assets with respect to or in exchange for shares of Common Stock (a “Corporate Event”),
the Company shall make appropriate provision to insure that the Holder will thereafter have the right to receive upon an exercise of this Warrant at any time after the consummation of the applicable Fundamental Transaction but prior to the
Expiration Date, in lieu of the shares of the Common Stock (or other securities, cash, assets or other property (except such items still issuable under Sections 3 and 4(a) above, which shall continue to be receivable thereafter)) issuable upon the
exercise of the Warrant prior to such Fundamental Transaction, such shares of stock, securities, cash, assets or any other property whatsoever (including warrants or other purchase or subscription rights) (collectively, the “Corporate Event
Consideration”) which the Holder would have been entitled to receive upon the happening of the applicable Fundamental Transaction had this Warrant been exercised immediately prior to the applicable Fundamental Transaction (without regard to
any limitations on the exercise of this Warrant). The provision made pursuant to the preceding sentence shall be in a form and substance reasonably satisfactory to the Holder. The provisions of this Section 4(b)

  
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shall apply similarly and equally to successive Fundamental Transactions and Corporate Events. Notwithstanding anything to the contrary, in the event of a Fundamental Transaction, the Company or
any Successor Entity shall, at the Holder’s option, exercisable at any time concurrently with, or within 30 days after, the consummation of the Fundamental Transaction (or, if later, the date of the public announcement of the applicable
Fundamental Transaction), purchase this Warrant from the Holder by paying to the Holder an amount of cash equal to the Black-Scholes Value of the remaining unexercised portion of this Warrant on the date of the consummation of such Fundamental
Transaction; provided, however, if the Fundamental Transaction is not within the Company’s control, including not approved by the Company’s Board of Directors, Holder shall only be entitled to receive from the Company or any Successor
Entity, as of the date of consummation of such Fundamental Transaction, the same type or form of consideration (and in the same proportion), at the Black-Scholes Value of the unexercised portion of this Warrant, that is being offered and paid to the
holders of Common Stock of the Company in connection with the Fundamental Transaction, whether that consideration be in the form of cash, shares or any combination thereof, or whether the holders of Common Stock are given the choice to receive from
among alternative forms of consideration in connection with the Fundamental Transaction. 
 5. NONCIRCUMVENTION. The Company hereby
covenants and agrees that the Company will not, by amendment of its Certificate of Incorporation or Bylaws, or through any reorganization, transfer of assets, consolidation, merger, scheme, arrangement, dissolution, issuance 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, and will at all times in good faith carry out all of the provisions of this Warrant and take all action as may be required to
protect the rights of the Holder. Without limiting the generality of the foregoing, the Company (i) shall not increase the par value of any shares of Common Stock receivable upon the exercise of this Warrant above the Exercise Price then in
effect, (ii) shall take all such actions as may be necessary or appropriate in order that the Company may validly and legally issue fully paid and nonassessable shares of Common Stock upon the exercise of this Warrant, and (iii) shall, so
long as any of the Warrants are outstanding, take all action necessary to reserve and keep available out of its authorized and unissued shares of Common Stock, solely for the purpose of effecting the exercise of the Warrants, the number of shares of
Common Stock as shall from time to time be necessary to effect the exercise of the Warrants then outstanding (without regard to any limitations on exercise). 

6. WARRANT HOLDER NOT DEEMED A STOCKHOLDER. Except as otherwise specifically provided herein, the Holder, solely in such Person’s
capacity as a holder of this Warrant, shall not be entitled to vote or receive dividends or be deemed the holder of capital stock of the Company for any purpose, nor shall anything contained in this Warrant be construed to confer upon the Holder,
solely in such Person’s capacity as the Holder of this Warrant, any of the rights of a stockholder of the Company or any right to vote, give or withhold consent to any corporate action (whether any reorganization, issue of stock,
reclassification of stock, consolidation, merger, conveyance or otherwise), receive notice of meetings, receive dividends or subscription rights, or otherwise, prior to the issuance to the Holder of the Warrant Shares which such Person is then
entitled to receive upon the due exercise of this Warrant. In addition, nothing contained in this Warrant shall be construed as imposing any liabilities on the Holder to purchase any securities (upon exercise of this Warrant or otherwise) or as a
stockholder of the 

  
 -10- 

 
Company, whether such liabilities are asserted by the Company or by creditors of the Company. Notwithstanding this Section 6, the Company shall provide the Holder with copies of the same
notices and other information given to the stockholders of the Company generally, contemporaneously with the giving thereof to the stockholders; provided that the failure to deliver such notice or any defect therein or in the delivery thereof shall
not affect the validity of any corporate action required to be specified in such notice. 
 7. REISSUANCE OF WARRANTS. 

(a) Transfer of Warrant. If this Warrant is to be transferred, the Holder shall surrender this Warrant to the Company, whereupon the
Company will forthwith issue and deliver upon the order of the Holder a new Warrant (in accordance with Section 7(d)), registered as the Holder may request, representing the right to purchase the number of Warrant Shares being transferred by
the Holder and, if less than the total number of Warrant Shares then underlying this Warrant is being transferred, a new Warrant (in accordance with Section 7(d)) to the Holder representing the right to purchase the number of Warrant Shares not
being transferred. 
 (b) Lost, Stolen or Mutilated Warrant. Upon receipt by the Company of evidence reasonably satisfactory to the
Company of the loss, theft, destruction or mutilation of this Warrant, and, in the case of loss, theft or destruction, of any indemnification undertaking by the Holder to the Company in customary form (but without the obligation to post a bond) and,
in the case of mutilation, upon surrender and cancellation of this Warrant, the Company shall execute and deliver to the Holder a new Warrant (in accordance with Section 7(d)) representing the right to purchase the Warrant Shares then
underlying this Warrant. 
 (c) Exchangeable for Multiple Warrants. This Warrant is exchangeable, upon the surrender hereof by the
Holder at the principal office of the Company, for a new Warrant or Warrants (in accordance with Section 7(d)) representing in the aggregate the right to purchase the number of Warrant Shares then underlying this Warrant, and each such new
Warrant will represent the right to purchase such portion of such Warrant Shares as is designated by the Holder at the time of such surrender. 

(d) Issuance of New Warrants. Whenever the Company is required to issue a new Warrant pursuant to the terms of this Warrant, such new
Warrant (i) shall be of like tenor with this Warrant, (ii) shall represent, as indicated on the face of such new Warrant, the right to purchase the Warrant Shares then underlying this Warrant (or in the case of a new Warrant being issued
pursuant to Section 7(a) or Section 7(c), the Warrant Shares designated by the Holder which, when added to the number of shares of Common Stock underlying the other new Warrants issued in connection with such issuance, does not exceed the
number of Warrant Shares then underlying this Warrant), (iii) shall have an issuance date, as indicated on the face of such new Warrant which is the same as the Issuance Date, and (iv) shall have the same rights and conditions as this Warrant.

  
 -11- 

 8. NOTICES. Whenever notice is required to be given under this Warrant, including,
without limitation, an Exercise Notice, unless otherwise provided herein, such notice shall be given in writing, (i) if delivered (a) from within the domestic United States, by first-class registered or certified airmail, or nationally
recognized overnight express courier, postage prepaid, electronic mail or by facsimile or (b) from outside the United States, by International Federal Express, electronic mail or facsimile, and (ii) will be deemed given (A) if
delivered by first-class registered or certified mail domestic, three (3) Business Days after so mailed, (B) if delivered by nationally recognized overnight carrier, one (1) Business Day after so mailed, (C) if delivered by
International Federal Express, two (2) Business Days after so mailed and (D) at the time of transmission, if delivered by electronic mail to the email address specified in this Section 8 prior to 5:00 p.m. (New York time) on a Trading
Day, (E) the next Trading Day after the date of transmission, if delivered by electronic mail to the email address specified in this Section 8 on a day that is not a Trading Day or later than 5:00 p.m. (New York time) on any Trading Day
and (F) if delivered by facsimile, upon electronic confirmation of delivery of such facsimile, and will be delivered and addressed as follows: 

(i) if to the Company, to: 

Altimmune, Inc. 
 910 Clopper
Road, Suite 201S 
 Gaithersburg, MD 20878 

Attention: William J. Enright 

Facsimile: (855) 557-1369 

Email: enright@altimmune.com 

(ii) if to the Holder, at such address or other contact information delivered by the Holder to Company or as is on the books and records of the
Company. 
 The Company shall provide the Holder with prompt written notice of all actions taken pursuant to this Warrant, including in reasonable detail a
description of such action and the reason therefor. Without limiting the generality of the foregoing, the Company will give written notice to the Holder (i) immediately upon any adjustment of the Exercise Price, setting forth in reasonable
detail, and certifying, the calculation of such adjustment and (ii) at least fifteen (15) days prior to the date on which the Company closes its books or takes a record (A) with respect to any dividend or distribution upon the shares
of Common Stock, (B) with respect to any grants, issuances or sales of any Options, Convertible Securities or rights to purchase stock, warrants, securities or other property pro rata to the record holders of any class of Common Stock or
(C) for determining rights to vote with respect to any Fundamental Transaction, dissolution or liquidation; provided in each case that such information shall be made known to the public prior to or in conjunction with such notice being
provided to the Holder; provided, further, 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. It is expressly
understood and agreed that the time of exercise specified by the Holder in each Exercise Notice shall be definitive and may not be disputed or challenged by the Company. 

9. AMENDMENT AND WAIVER. Except as otherwise provided herein, the provisions of this Warrant may be amended or waived and the Company
may take any action herein prohibited, or omit to perform any act herein required to be performed by it, only if the Company has obtained the written consent of each Holder. 

  
 -12- 

 10. GOVERNING LAW; JURISDICTION; JURY TRIAL. This Warrant shall be governed by and
construed and enforced in accordance with, and all questions concerning the construction, validity, interpretation and performance of this Warrant shall be governed by, the internal laws of the State of New York, without giving effect to any choice
of law or conflict of law provision or rule (whether of the State of New York or any other jurisdictions) that would cause the application of the laws of any jurisdictions other than the State of New York. The Company 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 brought in an inconvenient
forum or that the venue of such suit, action or proceeding is improper. The Company 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 to the
Company at the address set forth in Section 8(i) above or such other address as the Company subsequently delivers to the Holder 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. Nothing contained herein shall be deemed or operate to preclude the Holder from bringing suit or taking other legal action against the
Company in any other jurisdiction to collect on the Company’s obligations to the Holder, to realize on any collateral or any other security for such obligations, or to enforce a judgment or other court ruling in favor of the Holder. 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. THE COMPANY HEREBY IRREVOCABLY WAIVES ANY RIGHT IT MAY HAVE, AND AGREES NOT TO REQUEST, A JURY TRIAL FOR THE ADJUDICATION OF ANY DISPUTE
HEREUNDER OR IN CONNECTION WITH OR ARISING OUT OF THIS WARRANT OR ANY TRANSACTION CONTEMPLATED HEREBY. 
 11. DISPUTE RESOLUTION.
In the case of a dispute as to the determination of the Exercise Price or the arithmetic calculation of the Warrant Shares, the Company shall submit the disputed determinations or arithmetic calculations via facsimile or electronic mail within two
(2) Business Days of receipt of the Exercise Notice or other event giving rise to such dispute, as the case may be, to the Holder. If the Holder and the Company are unable to agree upon such determination or calculation of the Exercise Price or
the Warrant Shares within three (3) Business Days of such disputed determination or arithmetic calculation being submitted to the Holder, then the Company shall, within two (2) Business Days submit via facsimile or electronic mail
(a) the disputed determination of the Exercise Price to an independent, reputable investment bank selected by the Company and approved by the Holder or (b) the disputed arithmetic calculation of the Warrant Shares to the Company’s
independent, outside accountant. The Company shall cause at its expense the investment bank or the accountant, as the case may be, to perform the determinations or calculations and notify the Company and the Holder of the results no later than ten
(10) Business Days from the time it receives the disputed determinations or calculations. Such investment bank’s or accountant’s determination or calculation, as the case may be, shall be binding upon all parties absent demonstrable
error. 

  
 -13- 

 12. REMEDIES, OTHER OBLIGATIONS, BREACHES AND INJUNCTIVE RELIEF. The remedies
provided in this Warrant shall be cumulative and in addition to all other remedies available under this Warrant and any other Transaction Documents, at law or in equity (including a decree of specific performance and/or other injunctive relief), and
nothing herein shall limit the right of the Holder to pursue actual damages for any failure by the Company to comply with the terms of this Warrant. The Company acknowledges that a breach by it of its obligations hereunder will cause irreparable
harm to the Holder and that the remedy at law for any such breach may be inadequate. The Company therefore agrees that, in the event of any such breach or threatened breach, the holder of this Warrant shall be entitled, in addition to all other
available remedies, to an injunction restraining any breach, without the necessity of showing economic loss and without any bond or other security being required. 

13. TRANSFER. This Warrant and the Warrant Shares may be offered for sale, sold, transferred, pledged or assigned without the consent
of the Company. 
 14. SEVERABILITY; CONSTRUCTION; HEADINGS. If any provision of this Warrant is prohibited by law or otherwise
determined to be invalid or unenforceable by a court of competent jurisdiction, the provision that would otherwise be prohibited, invalid or unenforceable shall be deemed amended to apply to the broadest extent that it would be valid and
enforceable, and the invalidity or unenforceability of such provision shall not affect the validity of the remaining provisions of this Warrant so long as this Warrant as so modified continues to express, without material change, the original
intentions of the parties as to the subject matter hereof and the prohibited nature, invalidity or unenforceability of the provision(s) in question does not substantially impair the respective expectations or reciprocal obligations of the parties or
the practical realization of the benefits that would otherwise be conferred upon the parties. The parties will endeavor in good faith negotiations to replace the prohibited, invalid or unenforceable provision(s) with a valid provision(s), the effect
of which comes as close as possible to that of the prohibited, invalid or unenforceable provision(s). This Warrant shall be deemed to be jointly drafted by the Company and the Holder and shall not be construed against any Person as the drafter
hereof. The headings of this Warrant are for convenience of reference and shall not form part of, or affect the interpretation of, this Warrant. 

15. DISCLOSURE. Upon receipt or delivery by the Company of any notice in accordance with the terms of this Warrant, unless the Company
has in good faith determined that the matters relating to such notice do not constitute material, nonpublic information relating to the Company or its subsidiaries, the Company shall contemporaneously with any such receipt or delivery publicly
disclose such material, nonpublic information on a Current Report on Form 8-K or otherwise. In the event that the Company believes that a notice contains material, nonpublic information relating to the Company or its subsidiaries, the Company so
shall indicate to such Holder contemporaneously with delivery of such notice, and in the absence of any such indication, the Holder shall be allowed to presume that all matters relating to such notice do not constitute material, nonpublic
information relating to the Company or its subsidiaries. 

  
 -14- 

 16. CERTAIN DEFINITIONS. For purposes of this Warrant, the following terms shall have
the following meanings: 
 (a) “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 of 1933, as amended. 

(b) “Attribution Parties” means, collectively, the following Persons and entities: (i) any investment vehicle,
including, any funds, feeder funds or managed accounts, currently, or from time to time after the Subscription Date, directly or indirectly managed or advised by the Holder’s investment manager or any of its Affiliates or principals,
(ii) any direct or indirect Affiliates of the Holder or any of the foregoing, (iii) any Person acting or who could be deemed to be acting as a Group together with the Holder or any of the foregoing and (iv) any other Persons whose
beneficial ownership of the Company’s Common Stock would or could be aggregated with the Holder’s and the other Attribution Parties for purposes of Section 13(d) of the 1934 Act. For clarity, the purpose of the foregoing is to subject
collectively the Holder and all other Attribution Parties to the Maximum Percentage. 
 (c) “Bid Price” means, for any
security as of the particular time of determination, the bid price for such security on the Principal Market as reported by Bloomberg as of such time of determination, or, if the Principal Market is not the principal securities exchange or trading
market for such security, the bid price of such security on the principal securities exchange or trading market where such security is listed or traded as reported by Bloomberg as of such time of determination, or if the foregoing does not apply,
the bid price of such security in the over-the-counter market on the electronic bulletin board for such security as reported by Bloomberg as of such time of
determination, or, if no bid price is reported for such security by Bloomberg as of such time of determination, the average of the bid prices of any market makers for such security as reported in the “pink sheets” by OTC Markets Group Inc.
(formerly Pink Sheets LLC) as of such time of determination. If the Bid Price cannot be calculated for a security as of the particular time of determination on any of the foregoing bases, the Bid Price of such security as of such time of
determination shall be the fair market value as mutually determined by the Company and the Holder. If the Company and the Holder are unable to agree upon the fair market value of such security, then such dispute shall be resolved in accordance with
the procedures in Section 11. All such determinations shall be appropriately adjusted for any stock dividend, stock split, stock combination or other similar transaction during such period. 

(d) “Bloomberg” means Bloomberg Financial Markets. 

(e) “Black-Scholes Value” means the value of this Warrant calculated using the Black-Scholes Option Pricing Model obtained
from the “OV” function on Bloomberg determined as of the day immediately following the public announcement of the applicable Fundamental Transaction, or, if the Fundamental Transaction is not publicly announced, the date the Fundamental
Transaction is consummated, for pricing purposes and reflecting (i) a risk-free interest rate corresponding to the U.S. Treasury rate for a period equal to the remaining term of this Warrant as of such date of request, (ii) an expected
volatility equal to the greater of 100% and the 100 day volatility obtained from the HVT function on Bloomberg as of the Trading Day immediately following the public announcement of the applicable Fundamental Transaction, or, if the Fundamental
Transaction is not publicly announced, the date the Fundamental Transaction 

  
 -15- 

 
is consummated, (iii) the underlying price per share used in such calculation shall be the greater of (x) the highest Weighted Average Price of the Common Stock during the period
beginning on the Trading Day prior to the execution of definitive documentation relating to the applicable Fundamental Transaction and ending on (A) the Trading Day immediately following the public announcement of such Fundamental Transaction,
if the applicable Fundamental Transaction is publicly announced or (B) the Trading Day immediately following the consummation of the applicable Fundamental Transaction if the applicable Fundamental Transaction is not publicly announced and
(y) the sum of the price per share being offered in cash, if any, plus the value of any non-cash consideration, if any, being offered in the Fundamental Transaction, (iv) a zero cost of borrow and
(v) a 365 day annualization factor. 
 (f) “Business Day” means any day other than Saturday, Sunday or other day on
which commercial banks in The City of New York are authorized or required by law to remain closed. 
 (g) “Closing Bid
Price” and “Closing Sale Price” means, for any security as of any date, the last closing bid price and last closing trade price, respectively, for such security on the Principal Market, as reported by Bloomberg, or, if the
Principal Market begins to operate on an extended hours basis and does not designate the closing bid price or the closing trade price, as the case may be, then the last bid price or the last trade price, respectively, of such security prior to
4:00:00 p.m., New York time, as reported by Bloomberg, or, if the Principal Market is not the principal securities exchange or trading market for such security, the last closing bid price or last trade price, respectively, of such security on the
principal securities exchange or trading market where such security is listed or traded as reported by Bloomberg, or if the foregoing do not apply, the last closing bid price or last trade price, respectively, of such security in the over-the-counter market on the electronic bulletin board for such security as reported by Bloomberg, or, if no closing bid price or last trade price, respectively, is reported
for such security by Bloomberg, the average of the bid prices, or the ask prices, respectively, of any market makers for such security as reported in the OTC Link or “pink sheets” by OTC Markets Group Inc. (formerly Pink OTC Markets Inc.).
If the Closing Bid Price or the Closing Sale Price cannot be calculated for a security on a particular date on any of the foregoing bases, the Closing Bid Price or the Closing Sale Price, as the case may be, of such security on such date shall be
the fair market value as mutually determined by the Company and the Holder. If the Company and the Holder are unable to agree upon the fair market value of such security, then such dispute shall be resolved pursuant to Section 11. All such
determinations to be appropriately adjusted for any stock dividend, stock split, stock combination, reclassification or other similar transaction during the applicable calculation period. 

(h) “Common Stock” means (i) the Company’s Common Stock, par value $0.0001 per share, and (ii) any capital
stock into which such Common Stock shall have been changed or any capital stock resulting from a reclassification of such Common Stock. 

(i) “Convertible Securities” means any stock or securities (other than Options) directly or indirectly convertible into or
exercisable or exchangeable for shares of Common Stock. 

  
 -16- 

 (j) “Eligible Market” means The Nasdaq Capital Market, the NYSE American
LLC, The Nasdaq Global Select Market, The Nasdaq Global Market or The New York Stock Exchange, Inc. 
 (k) “Expiration
Date” means the date sixty (60) months after the Initial Exercisability Date or, if such date falls on a day other than a Business Day or on which trading does not take place on the Principal Market (a “Holiday”), the
next day that is not a Holiday. 
 (l) “Fundamental Transaction” means (A) that the Company shall, directly or
indirectly, including through subsidiaries, Affiliates or otherwise, in one or more related transactions, (i) consolidate or merge with or into (whether or not the Company is the surviving corporation) another Subject Entity, or (ii) sell,
assign, transfer, convey or otherwise dispose of all or substantially all of the properties or assets of the Company or any of its “significant subsidiaries” (as defined in Rule 1-02 of Regulation S-X) to one or more Subject Entities, or (iii) make, or allow one or more Subject Entities to make, or allow the Company to be subject to or have its shares of Common Stock be subject to or party to one or more
Subject Entities making, a purchase, tender or exchange offer that is accepted by the holders of at least either (x) 50% of the outstanding shares of Common Stock, (y) 50% of the outstanding shares of Common Stock calculated as if any shares of
Common Stock held by all Subject Entities making or party to, or Affiliated with any Subject Entities making or party to, such purchase, tender or exchange offer were not outstanding; or (z) such number of shares of Common Stock such that all
Subject Entities making or party to, or Affiliated with any Subject Entity making or party to, such purchase, tender or exchange offer, become collectively the beneficial owners (as defined in Rule 13d-3 under
the 1934 Act) of at least 50% of the outstanding shares of Common Stock, or (iv) consummate a stock purchase agreement or other business combination (including, without limitation, a reorganization, recapitalization, spin-off or scheme of arrangement) with one or more Subject Entities whereby all such Subject Entities, individually or in the aggregate, acquire, either (x) at least 50% of the outstanding shares of Common
Stock, (y) at least 50% of the outstanding shares of Common Stock calculated as if any shares of Common Stock held by all the Subject Entities making or party to, or Affiliated with any Subject Entity making or party to, such stock purchase
agreement or other business combination were not outstanding; or (z) such number of shares of Common Stock such that the Subject Entities become collectively the beneficial owners (as defined in Rule
13d-3 under the 1934 Act) of at least 50% of the outstanding shares of Common Stock, or (v) reorganize, recapitalize or reclassify its shares of Common Stock, (B) that the Company shall, directly or
indirectly, including through subsidiaries, Affiliates or otherwise, in one or more related transactions, allow any Subject Entity individually or the Subject Entities in the aggregate to be or become the “beneficial owner” (as defined in
Rule 13d-3 under the 1934 Act), directly or indirectly, whether through acquisition, purchase, assignment, conveyance, tender, tender offer, exchange, reduction in outstanding shares of Common Stock, merger,
consolidation, business combination, reorganization, recapitalization, spin-off, scheme of arrangement, reorganization, recapitalization or reclassification or otherwise in any manner whatsoever, of either
(x) at least 50% of the aggregate ordinary voting power represented by issued and outstanding shares of Common Stock, (y) at least 50% of the aggregate ordinary voting power represented by issued and outstanding shares of Common Stock not
held by all such Subject Entities as of the Subscription Date calculated as if any shares of Common Stock held by all such Subject Entities were not outstanding, or (z) a percentage of the aggregate ordinary voting power represented by issued

  
 -17- 

 
and outstanding shares of Common Stock or other equity securities of the Company sufficient to allow such Subject Entities to effect a statutory short form merger or other transaction requiring
other stockholders of the Company to surrender their Common Stock without approval of the stockholders of the Company or (C) directly or indirectly, including through subsidiaries, Affiliates or otherwise, in one or more related transactions,
the issuance of or the entering into any other instrument or transaction structured in a manner to circumvent, or that circumvents, the intent of this definition in which case this definition shall be construed and implemented in a manner otherwise
than in strict conformity with the terms of this definition to the extent necessary to correct this definition or any portion of this definition which may be defective or inconsistent with the intended treatment of such instrument or transaction.

 (m) “Group” means a “group” as that term is used in Section 13(d) of the 1934 Act and as defined in Rule 13d-5 thereunder. 
 (n) “Options” means any rights, warrants or options to subscribe for
or purchase shares of Common Stock or Convertible Securities. 
 (o) “Parent Entity” of a Person means an entity that,
directly or indirectly, controls the applicable Person, including such entity whose common stock or equivalent equity security is quoted or listed on an Eligible Market (or, if so elected by the Holder, any other market, exchange or quotation
system), or, if there is more than one such Person or such entity, the Person or such entity designated by the Holder or in the absence of such designation, such Person or entity with the largest public market capitalization as of the date of
consummation of the Fundamental Transaction. 
 (p) “Person” means an individual, a limited liability company, a
partnership, a joint venture, a corporation, a trust, an unincorporated organization, any other entity and a government or any department or agency thereof. 

(q) “Principal Market” means The Nasdaq Global Market. 

(r) “Standard Settlement Period” means the standard settlement period, expressed in a number of Trading Days, for the
Company’s primary trading market or quotation system with respect to the Common Stock that is in effect on the date of delivery of an applicable Exercise Notice. 

(s) “Subject Entity” means any Person, Persons or Group or any Affiliate or associate of any such Person, Persons or Group.

 (t) “Successor Entity” means one or more Person or Persons (or, if so elected by the Holder, the Company or Parent
Entity) formed by, resulting from or surviving any Fundamental Transaction or one or more Person or Persons (or, if so elected by the Holder, the Company or the Parent Entity) with which such Fundamental Transaction shall have been entered into.

 (u) “Trading Day” means any day on which the Common Stock is traded on the Principal Market, or, if the Principal Market
is not the principal trading market for the Common Stock, then on the principal securities exchange or securities market on which the Common Stock is then traded. 

  
 -18- 

 (v) “Transaction Documents” means any agreement entered into by and
between the Company and the Holder, as applicable. 
 (w) “Weighted Average Price” means, for any security as of any date,
the dollar volume-weighted average price for such security on the Principal Market during the period beginning at 9:30:01 a.m., New York time (or such other time as the Principal Market publicly announces is the official open of trading), and ending
at 4:00:00 p.m., New York time (or such other time as the Principal Market publicly announces is the official close of trading), as reported by Bloomberg through its “Volume at Price” function or, if the foregoing does not apply, the
dollar volume-weighted average price of such security in the over-the-counter market on the electronic bulletin board for such security during the period beginning at
9:30:01 a.m., New York time (or such other time as such market publicly announces is the official open of trading), and ending at 4:00:00 p.m., New York time (or such other time as such market publicly announces is the official close of trading), as
reported by Bloomberg, or, if no dollar volume-weighted average price is reported for such security by Bloomberg for such hours, the average of the highest Closing Bid Price and the lowest closing ask price of any of the market makers for such
security as reported in the OTC Link or “pink sheets” by OTC Markets Group Inc. (formerly Pink OTC Markets Inc.). If the Weighted Average Price cannot be calculated for a security on a particular date on any of the foregoing bases, the
Weighted Average Price of such security on such date shall be the fair market value as mutually determined by the Company and the Holder. If the Company and the Holder are unable to agree upon the fair market value of such security, then such
dispute shall be resolved pursuant to Section 11 but with the term “Weighted Average Price” being substituted for the term “Exercise Price.” All such determinations shall be appropriately adjusted for any stock dividend,
stock split, stock combination, reclassification or other similar transaction during the applicable calculation period. 
 [Signature Page
Follows] 

  
 -19- 

 IN WITNESS WHEREOF, the Company has caused this Warrant to Purchase Common Stock to be duly executed
as of the Issuance Date set out above. 
  

			
	ALTIMMUNE, INC.
		
	By:	 	
                     
        

	Name:
	Title:

 EXHIBIT A 

EXERCISE NOTICE 
 TO BE
EXECUTED BY THE REGISTERED HOLDER TO EXERCISE THIS 
 WARRANT TO PURCHASE COMMON STOCK 

ALTIMMUNE, INC. 
 The undersigned holder
hereby exercises the right to purchase                              shares of Common Stock (“Warrant
Shares”) of Altimmune, Inc., a Delaware corporation (the “Company”), evidenced by the attached Warrant to Purchase Common Stock (the “Warrant”). Capitalized terms used herein and not otherwise defined shall
have the respective meanings set forth in the Warrant. 
 1. Form of Exercise Price. The Holder intends that payment of the Exercise Price shall be made as:

                      a “Cash
Exercise” with respect to                              Warrant Shares; and/or 

                     a “Cashless
Exercise” with respect to                              Warrant Shares. 

2. Payment of Exercise Price. In the event that the holder has elected a Cash Exercise with respect to some or all of the Warrant Shares to be issued pursuant
hereto, the holder shall pay the Aggregate Exercise Price in the sum of $                             to the
Company in accordance with the terms of the Warrant. 
 3. Delivery of Warrant Shares. The Company shall deliver to the holder
                     Warrant Shares in accordance with the terms of the Warrant. 

 

	
	Date:                                  ,
            
	
	  

	Name of Registered Holder

  

			
	By:	 	  

		 	Name:
		 	Title:

 ACKNOWLEDGMENT 

The Company hereby acknowledges this Exercise Notice and hereby directs Continental Stock Transfer & Trust Company, LLC to issue the above indicated
number of shares of Common Stock on or prior to the applicable Share Delivery Date. 
  

			
	ALTIMMUNE, INC.
	
	By:                                   
                                     
	Name:
	Title:Exhibit 10.1

 EXHIBIT 10.1 

FORM OF 
 SECURITIES
PURCHASE AGREEMENT 
 This Securities Purchase Agreement (this “Agreement”) is dated as of October 8, 2018,
between Altimmune, Inc., a Delaware corporation (the “Company”), and each purchaser identified on the signature pages hereto (each, including its successors and assigns, a “Purchaser” and collectively the
“Purchasers”). 
 WHEREAS, subject to the terms and conditions set forth in this Agreement and pursuant to an effective
registration statement under the Securities Act of 1933, as amended (the “Securities Act”), the Company desires to issue and sell to each Purchaser, and each Purchaser, severally and not jointly, desires to purchase from the
Company, securities of the Company as more fully described in this Agreement. 
 NOW, THEREFORE, IN CONSIDERATION of the mutual covenants
contained in this Agreement, and for other good and valuable consideration the receipt and adequacy of which are hereby acknowledged, the Company and each Purchaser agree as follows: 

ARTICLE I. 
 DEFINITIONS

 1.1 Definitions. In addition to the terms defined elsewhere in this Agreement, for all purposes of this Agreement, the following
terms have the meanings set forth in this Section 1.1: 
 “Acquiring Person” shall have the meaning
ascribed to such term in Section 4.4. 
 “Action” means an action, suit, inquiry, notice of violation,
proceeding or investigation pending or, to the knowledge of the Company, threatened against or affecting the Company, any Subsidiary or any of their respective properties before or by any court, arbitrator, governmental or administrative agency or
regulatory authority (federal, state, county, local or foreign). 
 “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. 

“Board of Directors” means the board of directors of the Company. 

“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. 

“Closing” means the closing of the purchase and sale of the Shares, the
Pre-Funded Warrants, if any, and the Warrants comprising the Units pursuant to Section 2.1. 

  
 1 

 “Closing Date” means the Trading Day on which all of the
Transaction Documents have been executed and delivered by the applicable parties thereto, and all conditions precedent to (i) the Purchasers’ obligations to pay the Subscription Amount and (ii) the Company’s obligations to
deliver the Securities, in each case, have been satisfied or waived, but in no event later than the second (2nd) Trading Day following the date hereof. 

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

“Common Stock” means the common stock of the Company, par value $0.0001 per share, and any other class of
securities into which such securities may hereafter be reclassified or changed. 
 “Common Stock
Equivalents” means any securities of the Company or the Subsidiaries which 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. 

“Common Unit” means a fixed combination of one Share and one Warrant to purchase one Warrant Share. 

“Common Unit Subscription Amount” means, as to each Purchaser, the aggregate amount to be paid for Common
Units purchased hereunder as specified below such Purchaser’s name on the signature page of this Agreement and next to the heading “Common Unit Subscription Amount,” in United States dollars and in immediately available funds. 

“Disclosure Package” means (i) the Prospectus, (ii) the Prospectus Supplement used most recently
prior to the Purchaser’s execution and delivery of this Agreement, (iii) any issuer free writing prospectus, as defined in Rule 433 under the Securities Act (an “Issuer Free Writing Prospectus), (iv) the final term sheet, if
any, prepared and filed in connection with the Offering, (v) any other free writing prospectus, if any, as defined in Rule 405 under the Securities Act (a “Free Writing Prospectus), (vi) oral communication by the Placement Agent of
pricing information, and (vii) with respect to clauses (i) and (ii) each document incorporated therein by reference. 

“Disclosure Schedules” means the Disclosure Schedules of the Company delivered concurrently herewith. 

“Evaluation Date” shall have the meaning ascribed to such term in Section 3.1(s). 

“Exchange Act” means the Securities Exchange Act of 1934, as amended, and the rules and regulations
promulgated thereunder. 
 “FCPA” means the Foreign Corrupt Practices Act of 1977, as amended. 

“GAAP” shall have the meaning ascribed to such term in Section 3.1(g). 

  
 2 

 “Indebtedness” shall have the meaning ascribed to such term
in Section 3.1(aa). 
 “Intellectual Property Rights” shall have the meaning ascribed to such term in
Section 3.1(p). 
 “Liens” means a lien, charge, pledge, security interest, encumbrance, right of first
refusal, preemptive right or other restriction. 
 “LS” means Lowenstein Sandler LLP, with offices located
at 1251 Avenue of the Americas, New York, New York 10020. 
 “Material Adverse Effect” shall have the
meaning assigned to such term in Section 3.1(b). 
 “Material Permits” shall have the meaning ascribed
to such term in Section 3.1(n). 
 “Offering” means the offering of the Securities pursuant to this
Agreement and the Disclosure Package. 
 “Per Common Unit Purchase Price” equals $5.40, subject to
adjustment for reverse and forward stock splits, stock dividends, stock combinations and other similar transactions of the Common Stock that occur after the date of this Agreement. 

“Per Pre-Funded Unit Purchase Price” equals $5.39, subject to
adjustment for reverse and forward stock splits, stock dividends, stock combinations and other similar transactions of the Common Stock that occur after the date of this Agreement. 

“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. 

“Placement Agent” means Roth Capital Partners, LLC. 

“Pre-Funded Warrants” means, collectively, the Common Stock purchase
warrants delivered to the Purchasers at the Closing in accordance with Section 2.2(a) hereof, which Pre-Funded Warrants shall be exercisable from the date of issuance in the form of Exhibit A
attached hereto. 
 “Pre-Funded Warrant Shares” means the shares of
Common Stock issuable upon exercise of the Pre-Funded Warrants. 
 “Pre-Funded Unit” means a fixed combination of one Pre-Funded Warrant to purchase one Pre-Funded Warrant Share and one Warrant
to purchase one Warrant Share. 
 “Pre-Funded Unit Subscription
Amount” means, as to each Purchaser, the aggregate amount to be paid for Pre-Funded Units purchased hereunder as specified below such Purchaser’s name on the signature page of this Agreement and
next to the heading “Common Unit Subscription Amount,” in United States dollars and in immediately available funds. 

  
 3 

 “Proceeding” means an action, claim, suit, investigation or
proceeding (including, without limitation, an informal investigation or partial proceeding, such as a deposition), whether commenced or threatened. 

“Prospectus” means the final prospectus filed for the Registration Statement. 

“Prospectus Supplement” means the supplement to the Prospectus complying with Rule 424(b) of the Securities
Act that is filed with the Commission and delivered by the Company to each Purchaser at or prior to the Closing. 

“Purchaser Party” shall have the meaning ascribed to such term in Section 4.7. 

“Registration Statement” means the effective registration statement with Commission file No. 333-217034 which registers the sale of the Shares, the Pre-Funded Warrants, the Pre-Funded Warrant Shares, the Warrants and
the Warrant Shares. 
 “Required Approvals” shall have the meaning ascribed to such term in
Section 3.1(e). 
 “Rule 144” means Rule 144 promulgated by the Commission pursuant to the Securities
Act, as such Rule may be amended or interpreted from time to time, or any similar rule or regulation hereafter adopted by the Commission having substantially the same purpose and effect as such Rule. 

“Rule 424” means Rule 424 promulgated by the Commission pursuant to the Securities Act, as such Rule may be
amended or interpreted from time to time, or any similar rule or regulation hereafter adopted by the Commission having substantially the same purpose and effect as such Rule. 

“SEC Reports” shall have the meaning ascribed to such term in Section 3.1(g). 

“Securities” means, collectively, the Shares, the Pre-Funded Warrants,
the Pre-Funded Warrant Shares and the Warrant Shares. 
 “Securities
Act” means the Securities Act of 1933, as amended, and the rules and regulations promulgated thereunder. 

“Shares” means the shares of Common Stock issued or issuable to each Purchaser pursuant to this Agreement.

 “Short Sales” means all “short sales” as defined in Rule 200 of Regulation SHO under the
Exchange Act (but shall not be deemed to include locating and/or borrowing shares of Common Stock).

  
 4 

 “Subscription Amount” means, as to each Purchaser, the
aggregate amount to be paid for Common Units and Pre-Funded Units purchased hereunder as specified below such Purchaser’s name on the signature page of this Agreement and next to the heading
“Subscription Amount,” in United States dollars and in immediately available funds. 

“Subsidiary” means any subsidiary of the Company as set forth on Schedule 3.1(a), and shall, where
applicable, also include any direct or indirect subsidiary of the Company formed or acquired after the date hereof. 

“Trading Day” means a day on which the principal Trading Market is open for trading. 

“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 American, the Nasdaq Capital Market, the Nasdaq Global Market, the Nasdaq Global Select Market, the New York Stock Exchange, OTCQB or OTCQX (or any successors to any of the foregoing). 

“Transaction Documents” means this Agreement, the Pre-Funded Warrants,
the Warrants, all exhibits and schedules thereto and hereto and any other documents or agreements executed in connection with the transactions contemplated hereunder. 

“Transfer Agent” means Continental Stock Transfer & Trust Company, the current transfer agent of the
Company, with a mailing address of 1 State Street 30th Floor, New York, NY 10004-1561 and a facsimile number of 212-616-7615, and any successor transfer agent of the
Company. 
 “Units” means, collectively, Common Units and Pre-Funded
Units. 
 “Warrants” means, collectively, the Common Stock purchase warrants delivered to the Purchasers at
the Closing in accordance with Section 2.2(a) hereof, which Warrants shall be exercisable from the date of issuance and have a term of exercise equal to five (5) years from the initial exercise date, in the form of Exhibit B
attached hereto. 
 “Warrant Shares” means the shares of Common Stock issuable upon exercise of the
Warrants. 
 ARTICLE II. 

PURCHASE AND SALE 
 2.1
Closing. On the Closing Date, upon the terms and subject to the conditions set forth herein, substantially concurrent with the execution and delivery of this Agreement by the parties hereto, the Company agrees to sell, and the Purchasers,
severally and not jointly, agree to purchase, up to an aggregate of $25,000,000 of Units. Each Purchaser’s Subscription Amount as set forth on the signature page hereto executed by such Purchaser shall be made available for “Delivery
Versus Payment” settlement with the Company or its designee. The Company shall deliver to each Purchaser its respective Shares, Pre-Funded Warrants, if any, and Warrants, and the Company and each
Purchaser shall deliver the other items set forth in Section 2.2 deliverable 

  
 5 

 
at the Closing. Upon satisfaction of the covenants and conditions set forth in Sections 2.2 and 2.3, the Closing shall occur at the offices of LS or such other location as the parties shall
mutually agree. Unless otherwise directed by the Placement Agent, settlement of the Shares, the Pre-Funded Warrants and the Warrants shall occur via “Delivery Versus Payment”
(“DVP”) (i.e., on the Closing Date, the Company shall issue the Shares registered in the Purchasers’ names and addresses and released by the Transfer Agent directly to the account(s) at the Placement Agent identified by
each Purchaser; upon receipt of such Shares, the Placement Agent shall promptly electronically deliver such Shares to the applicable Purchaser, and payment therefor shall be made by the Placement Agent (or its clearing firm) by wire transfer to the
Company), and delivery of the Pre-Funded Warrants and the Warrants shall be made by physical delivery to be received or directed by each Purchaser no later than one (1) business day following the Closing
Date. 
 2.2 Deliveries. 

(a) On or prior to the Closing Date, the Company shall deliver or cause to be delivered to each Purchaser the following: 

(i) this Agreement duly executed by the Company; 

(ii) subject to the last sentence of Section 2.1, the Company shall have provided each Purchaser with the Company’s
wire instructions, on Company letterhead and executed by the Chief Executive Officer or Chief Financial Officer; 
 (iii)
subject to the last sentence of Section 2.1, a copy of the irrevocable instructions to the Transfer Agent instructing the Transfer Agent to deliver on an expedited basis via The Depository Trust Company Deposit or Withdrawal at Custodian system
(“DWAC”) Shares equal to such Purchaser’s Common Unit Subscription Amount divided by the Per Common Unit Purchase Price, registered in the name of such Purchaser; 

(iv) If applicable, a Pre-Funded Warrant registered in the name of such Purchaser to
purchase up to a number of Pre-Funded Warrant Shares equal to such Purchaser’s Pre-Funded Warrant Subscription Amount, with an exercise price equal to $0.01,
subject to adjustment therein; 
 (v) A Warrant registered in the name of such Purchaser to purchase up to a number of shares
of Common Stock equal to 100% of such Purchaser’s Shares and Pre-Funded Warrants, if any, with an exercise price equal to $5.40, subject to adjustment therein; and 

(vi) the Prospectus and Prospectus Supplement (which may be delivered in accordance with Rule 172 under the Securities Act).

 (b) On or prior to the Closing Date, each Purchaser shall deliver or cause to be delivered to the Company, as applicable,
the following: 
 (i) this Agreement duly executed by such Purchaser; and 

  
 6 

 (ii) such Purchaser’s Subscription Amount, which shall be made
available for “Delivery Versus Payment” settlement with the Company or its designee. 
 2.3 Closing Conditions. 

 (a) The obligations of the Company hereunder in connection with the Closing are subject to the following conditions being
met: 
 (i) the accuracy in all material respects (or, to the extent representations or warranties are qualified by
materiality or Material Adverse Effect, in all respects) on the Closing Date of the representations and warranties of the Purchasers contained herein (unless as of a specific date therein in which case they shall be accurate as of such date); 

(ii) all obligations, covenants and agreements of each Purchaser required to be performed at or prior to the Closing Date shall
have been performed; and 
 (iii) the delivery by each Purchaser of the items set forth in Section 2.2(b) of this
Agreement. 
 (b) The respective obligations of the Purchasers hereunder in connection with the Closing are subject to the
following conditions being met: 
 (i) the accuracy in all material respects (or, to the extent representations or warranties
are qualified by materiality or Material Adverse Effect, in all respects) when made and on the Closing Date of the representations and warranties of the Company contained herein (unless as of a specific date therein in which case they shall be
accurate as of such date); 
 (ii) all obligations, covenants and agreements of the Company required to be performed at or
prior to the Closing Date shall have been performed; 
 (iii) the delivery by the Company of the items set forth in
Section 2.2(a) of this Agreement; 
 (iv) there shall have been no Material Adverse Effect with respect to the Company
since the date hereof; and 
 (v) from the date hereof to the Closing Date, trading in the Common Stock shall not have been
suspended by the Commission or the Company’s principal Trading Market for a period in excess of two hours, and, at any time prior to the Closing Date, trading in securities generally as reported by Bloomberg L.P. shall not have been suspended
or limited, or minimum prices shall not have been established on securities whose trades are reported by such service, or on any Trading Market, nor shall a banking moratorium have been declared either by the United States or New York State
authorities nor shall there have occurred any 

  
 7 

 
material outbreak or escalation of hostilities or other national or international calamity of such magnitude in its effect on, or any material adverse change in, any financial market which, in
each case, in the reasonable judgment of such Purchaser, makes it impracticable or inadvisable to purchase the Shares, the Pre-Funded Warrants, if any, and the Warrants at the Closing. 

ARTICLE III. 

REPRESENTATIONS AND WARRANTIES 

3.1 Representations and Warranties of the Company. Except, in each case, as disclosed in the Disclosure Package, the Company hereby
makes the following representations and warranties to each Purchaser: 
 (a) Subsidiaries. The Company owns, directly
or indirectly, all of the capital stock or other equity interests of each Subsidiary free and clear of any Liens, and all of the issued and outstanding shares of capital stock of each Subsidiary are validly issued and are fully paid, non-assessable and free of preemptive and similar rights to subscribe for or purchase securities. If the Company has no subsidiaries, all other references to the Subsidiaries or any of them in the Transaction
Documents shall be disregarded. 
 (b) Organization and Qualification. The Company and each of the Subsidiaries is an
entity duly incorporated or otherwise organized, validly existing and in good standing under the laws of the jurisdiction of its incorporation or organization, with the requisite power and authority to own and use its properties and assets and to
carry on its business as currently conducted. Neither the Company nor any Subsidiary is in violation nor default of any of the provisions of its respective certificate or articles of incorporation, bylaws or other organizational or charter
documents. Each of the Company and the Subsidiaries is duly qualified to conduct business and is in good standing as a foreign corporation or other entity in each jurisdiction in which the nature of the business conducted or property owned by it
makes such qualification necessary, except where the failure to be so qualified or in good standing, as the case may be, could not have or reasonably be expected to result in: (i) a material adverse effect on the legality, validity or
enforceability of any Transaction Document, (ii) a material adverse effect on the results of operations, assets, business, prospects or condition (financial or otherwise) of the Company and its subsidiaries (each, a
“Subsidiary” and, collectively, the “Subsidiaries”), taken as a whole, or (iii) a material adverse effect on the Company’s ability to perform in any material respect on a timely basis its obligations under any
Transaction Document (any of (i), (ii) or (iii), a “Material Adverse Effect”) and no Proceeding has been instituted in any such jurisdiction revoking, limiting or curtailing or seeking to revoke, limit or curtail such power and
authority or qualification. 
 (c) Authorization; Enforcement. The Company has the requisite corporate power and
authority to enter into and to consummate the transactions contemplated by this Agreement and each of the other Transaction Documents and otherwise to carry out its obligations hereunder and thereunder. The execution and delivery of this Agreement
and each of the other Transaction Documents by the Company and the consummation by it of the transactions contemplated hereby and thereby have been duly authorized by all 

  
 8 

 
necessary action on the part of the Company and no further action is required by the Company, the Board of Directors or the Company’s stockholders in connection herewith or therewith other
than in connection with the Required Approvals. This Agreement and each other Transaction Document to which it is a party has been (or upon delivery will have been) duly executed by the Company and, when delivered in accordance with the terms hereof
and thereof, will constitute the valid and binding obligation of the Company enforceable against the Company in accordance with its terms, except (i) as limited by general equitable principles and applicable bankruptcy, insolvency,
reorganization, moratorium and other laws of general application affecting enforcement of creditors’ rights generally, (ii) as limited by laws relating to the availability of specific performance, injunctive relief or other equitable
remedies and (iii) insofar as indemnification and contribution provisions may be limited by applicable law. 
 (d) No
Conflicts. The execution, delivery and performance by the Company of this Agreement and the other Transaction Documents to which it is a party, the issuance and sale of the Securities and the consummation by it of the transactions contemplated
hereby and thereby do not and will not (i) conflict with or violate any provision of the Company’s or any Subsidiary’s certificate or articles of incorporation, bylaws or other organizational or charter documents, or
(ii) conflict with, or constitute a default (or an event that with notice or lapse of time or both would become a default) under, result in the creation of any Lien upon any of the properties or assets of the Company or any Subsidiary, or give
to others any rights of termination, amendment, acceleration or cancellation (with or without notice, lapse of time or both) of, any agreement, credit facility, debt or other instrument (evidencing a Company or Subsidiary debt or otherwise) or other
understanding to which the Company or any Subsidiary is a party or by which any property or asset of the Company or any Subsidiary is bound or affected, or (iii) subject to the Required Approvals, conflict with or result in a violation of any
law, rule, regulation, order, judgment, injunction, decree or other restriction of any court or governmental authority to which the Company or a Subsidiary is subject (including federal and state securities laws and regulations), or by which any
property or asset of the Company or a Subsidiary is bound or affected; except as could not have or reasonably be expected to result in a Material Adverse Effect. 

(e) Filings, Consents and Approvals. The Company is not required to obtain any consent, waiver, authorization or order
of, give any notice to, or make any filing or registration with, any court or other federal, state, local or other governmental authority or other Person in connection with the execution, delivery and performance by the Company of the Transaction
Documents, other than: (i) the filings required pursuant to Section 4.3 of this Agreement, (ii) the filing with the Commission of the Prospectus Supplement, (iii) application(s) to each applicable Trading Market for the listing
of the Shares, the Pre-Funded Warrant Shares and the Warrant Shares for trading thereon in the time and manner required thereby and (iv) such filings as are required to be made under applicable state
securities laws (collectively, the “Required Approvals”). 

  
 9 

 (f) Issuance of the Shares, the
Pre-Funded Warrant Shares and the Warrant Shares; Registration. The Shares are duly authorized and, when issued and paid for in accordance with the applicable Transaction Documents, will be duly and
validly issued, fully paid and nonassessable, free and clear of all Liens imposed by the Company. The Pre-Funded Warrant Shares, when issued in accordance with the terms of the
Pre-Funded Warrants, will be validly issued, fully paid and nonassessable, free and clear of all Liens imposed by the Company. The Warrant Shares, when issued in accordance with the terms of the Warrants, will
be validly issued, fully paid and nonassessable, free and clear of all Liens imposed by the Company. The Company has reserved from its duly authorized capital stock the maximum number of shares of Common Stock issuable pursuant to this Agreement,
the Pre-Funded Warrants and the Warrants. The Company has prepared and filed the Registration Statement in conformity with the requirements of the Securities Act, which became effective on April 6, 2017
(the “Effective Date”), including the Prospectus, and such amendments and supplements thereto as may have been required to the date of this Agreement. The Registration Statement is effective under the Securities Act and no stop
order preventing or suspending the effectiveness of the Registration Statement or suspending or preventing the use of the Prospectus has been issued by the Commission and no proceedings for that purpose have been instituted or, to the knowledge of
the Company, are threatened by the Commission. The Company, if required by the rules and regulations of the Commission, shall file the Prospectus with the Commission pursuant to Rule 424(b). At the time the Registration Statement and any amendments
thereto became effective, at the date of this Agreement and at the Closing Date, the Registration Statement and any amendments thereto conformed and will conform in all material respects to the requirements of the Securities Act and did not and will
not contain any untrue statement of a material fact or omit to state any material fact required to be stated therein or necessary to make the statements therein not misleading; and the Prospectus and any amendments or supplements thereto, at time
the Prospectus or any amendment or supplement thereto was issued and at the Closing Date, conformed and will conform in all material respects to the requirements of the Securities Act and did not and will not contain an untrue statement of a
material fact or omit to state a material fact necessary in order to make the statements therein, in the light of the circumstances under which they were made, not misleading. The Company was at the time of the filing of the Registration Statement
eligible to use Form S-3. The Company is eligible to use Form S-3 under the Securities Act and it meets the transaction requirements set forth in General Instruction
I.B.1 of Form S-3. 
 (g) Capitalization. The capitalization of the Company is
as set forth in the Disclosure Package and the SEC Reports (defined below). The Company has not issued any capital stock since its most recently filed periodic report under the Exchange Act, other than pursuant to the exercise of employee stock
options under the Company’s stock option plans, the issuance of shares of Common Stock to employees pursuant to the Company’s employee stock purchase plans and pursuant to the conversion and/or exercise of Common Stock Equivalents
outstanding as of the date of the most recently filed periodic report under the Exchange Act. Except as disclosed in the SEC Reports, no Person has any right of first refusal, preemptive right, right of participation, or any similar right to
participate in the transactions contemplated by the Transaction Documents. Except as a result of the purchase and sale of the Shares, the Pre-Funded Warrants and the Warrants, there are no outstanding options,
warrants, scrip rights to subscribe to, calls or commitments of any character whatsoever relating to, or securities, rights or obligations convertible into or exercisable or exchangeable for, or giving any

  
 10 

 
Person any right to subscribe for or acquire, any shares of Common Stock or the capital stock of any Subsidiary, or contracts, commitments, understandings or arrangements by which the Company or
any Subsidiary is or may become bound to issue additional shares of Common Stock or Common Stock Equivalents or capital stock of any Subsidiary. The issuance and sale of the Securities will not obligate the Company or any Subsidiary to issue shares
of Common Stock or other securities to any Person (other than the Purchasers) and, except as disclosed in the SEC Reports, will not result in a right of any holder of Company securities to adjust the exercise, conversion, exchange or reset price
under any of such securities. There are no outstanding securities or instruments of the Company or any Subsidiary that contain any redemption or similar provisions, and there are no contracts, commitments, understandings or arrangements by which the
Company or any Subsidiary is or may become bound to redeem a security of the Company or such Subsidiary. The Company does not have any stock appreciation rights or “phantom stock” plans or agreements or any similar plan or agreement. All
of the outstanding shares of capital stock of the Company are duly authorized, validly issued, fully paid and nonassessable, have been issued in compliance with all federal and state securities laws, and none of such outstanding shares was issued in
violation of any preemptive rights or similar rights to subscribe for or purchase securities. No further approval or authorization of any stockholder, the Board of Directors or others is required for the issuance and sale of the Securities. There
are no stockholders agreements, voting agreements or other similar agreements with respect to the Company’s capital stock to which the Company is a party or, to the knowledge of the Company, between or among any of the Company’s
stockholders. 
 (h) SEC Reports; Financial Statements. The Company has filed all reports, schedules, forms,
statements and other documents required to be filed by the Company under the Securities Act and the Exchange Act, including pursuant to Section 13(a) or 15(d) thereof, for the two years preceding the date hereof (or such shorter period as the
Company was required by law or regulation to file such material) (the foregoing materials, including the exhibits thereto and documents incorporated by reference therein, together with the Prospectus and the Prospectus Supplement, being collectively
referred to herein as the “SEC Reports”) on a timely basis or has received a valid extension of such time of filing and has filed any such SEC Reports prior to the expiration of any such extension. As of their respective dates, the
SEC Reports complied in all material respects with the requirements of the Securities Act and the Exchange Act, as applicable, and none of the SEC Reports, when filed, contained any untrue statement of a material fact or omitted to state a material
fact required to be stated therein or necessary in order to make the statements therein, in the light of the circumstances under which they were made, not misleading. The Company has not in the past five (5) years been an issuer subject to Rule
144(i) under the Securities Act. The financial statements of the Company included in the SEC Reports comply in all material respects with applicable accounting requirements and the rules and regulations of the Commission with respect thereto as in
effect at the time of filing. Such financial statements have been prepared in accordance with United States generally accepted accounting principles applied on a consistent basis during the periods involved (“GAAP”), except as may
be otherwise specified in such financial statements or the notes thereto and except that unaudited financial statements may not contain all footnotes required by GAAP, and fairly present in all material respects the financial position of the Company
and its consolidated Subsidiaries as of and for the dates thereof and the results of operations and cash flows for the periods then ended, subject, in the case of unaudited statements, to normal, immaterial,
year-end audit adjustments. 

  
 11 

 (i) Material Changes; Undisclosed Events, Liabilities or
Developments. Since the date of the latest audited financial statements included within the SEC Reports, except as set forth in the SEC Reports and the Disclosure Package (i) there has been no event, occurrence or development that has had
or that could reasonably be expected to result in a Material Adverse Effect, (ii) the Company has not incurred any liabilities (contingent or otherwise) other than (A) trade payables and accrued expenses incurred in the ordinary course of
business consistent with past practice and (B) liabilities not required to be reflected in the Company’s financial statements pursuant to GAAP or disclosed in filings made with the Commission, (iii) the Company has not altered its
method of accounting, (iv) the Company has not declared or made any dividend or distribution of cash or other property to its stockholders or purchased, redeemed or made any agreements to purchase or redeem any shares of its capital stock and
(v) the Company has not issued any equity securities to any officer, director or Affiliate, except pursuant to existing Company stock option plans. The Company does not have pending before the Commission any request for confidential treatment
of information. 
 (j) Litigation. There is no Action which (i) adversely affects or challenges the legality,
validity or enforceability of any of the Transaction Documents or the Securities or (ii) could, if there were an unfavorable decision, have or reasonably be expected to result in a Material Adverse Effect. Neither the Company nor any
Subsidiary, nor any director or officer thereof, is or has been the subject of any Action involving a claim of violation of or liability under federal or state securities laws or a claim of breach of fiduciary duty. There has not been, and to the
knowledge of the Company, there is not pending or contemplated, any investigation by the Commission involving the Company or any current or former director or officer of the Company. The Commission has not issued any stop order or other order
suspending the effectiveness of any registration statement filed by the Company or any Subsidiary under the Exchange Act or the Securities Act. 

(k) Labor Relations. No labor dispute exists or, to the knowledge of the Company, is imminent with respect to any of the
employees of the Company, which could reasonably be expected to result in a Material Adverse Effect. None of the Company’s or its Subsidiaries’ employees is a member of a union that relates to such employee’s relationship with the
Company or such Subsidiary, and neither the Company nor any of its Subsidiaries is a party to a collective bargaining agreement, and the Company and its Subsidiaries believe that their relationships with their employees are good. To the knowledge of
the Company, no executive officer of the Company or any Subsidiary, is, or is now expected to be, in violation of any material term of any employment contract, confidentiality, disclosure or proprietary information agreement or non-competition agreement, or any other contract or agreement or any restrictive covenant in favor of any third party, and the continued employment of each such executive officer does not subject the Company or any
of its Subsidiaries to any liability with respect to any of the foregoing matters. The Company and its Subsidiaries are in 

  
 12 

 
compliance with all U.S. federal, state, local and foreign laws and regulations relating to employment and employment practices, terms and conditions of employment and wages and hours, except
where the failure to be in compliance could not, individually or in the aggregate, reasonably be expected to have a Material Adverse Effect. 

(l) Compliance. Neither the Company nor any Subsidiary: (i) is in default under or in violation of (and no event
has occurred that has not been waived that, with notice or lapse of time or both, would result in a default by the Company or any Subsidiary under), nor has the Company or any Subsidiary received notice of a claim that it is in default under or that
it is in violation of, any indenture, loan or credit agreement or any other agreement or instrument to which it is a party or by which it or any of its properties is bound (whether or not such default or violation has been waived), (ii) is in
violation of any judgment, decree or order of any court, arbitrator or other governmental authority or (iii) is or has been in violation of any statute, rule, ordinance or regulation of any governmental authority, including without limitation
all foreign, federal, state and local laws relating to taxes, environmental protection, occupational health and safety, product quality and safety and employment and labor matters, except in each case as could not have or reasonably be expected to
result in a Material Adverse Effect. 
 (m) Environmental Laws. The Company and its Subsidiaries (i) are in
compliance with all federal, state, local and foreign laws relating to pollution or protection of human health or the environment (including ambient air, surface water, groundwater, land surface or subsurface strata), including laws relating to
emissions, discharges, releases or threatened releases of chemicals, pollutants, contaminants, or toxic or hazardous substances or wastes (collectively, “Hazardous Materials”) into the environment, or otherwise relating to the
manufacture, processing, distribution, use, treatment, storage, disposal, transport or handling of Hazardous Materials, as well as all authorizations, codes, decrees, demands, or demand letters, injunctions, judgments, licenses, notices or notice
letters, orders, permits, plans or regulations, issued, entered, promulgated or approved thereunder (“Environmental Laws”); (ii) have received all permits licenses or other approvals required of them under applicable Environmental
Laws to conduct their respective businesses; and (iii) are in compliance with all terms and conditions of any such permit, license or approval where in each clause (i), (ii) and (iii), the failure to so comply could be reasonably expected to
have, individually or in the aggregate, a Material Adverse Effect. 
 (n) Regulatory Permits. The Company and the
Subsidiaries possess all certificates, authorizations and permits issued by the appropriate federal, state, local or foreign regulatory authorities necessary to conduct their respective businesses as described in the SEC Reports, except where the
failure to possess such permits could not reasonably be expected to result in a Material Adverse Effect (“Material Permits”), and neither the Company nor any Subsidiary has received any notice of proceedings relating to the
revocation or modification of any Material Permit. 

  
 13 

 (o) Title to Assets. The Company and the Subsidiaries have good and
marketable title in fee simple to all real property owned by them and good and marketable title in all personal property owned by them that is material to the business of the Company and the Subsidiaries, in each case free and clear of all Liens,
except for (i) Liens as do not materially affect the value of such property and do not materially interfere with the use made and proposed to be made of such property by the Company and the Subsidiaries and (ii) Liens for the payment of
federal, state or other taxes, for which appropriate reserves have been made therefor in accordance with GAAP and, the payment of which is neither delinquent nor subject to penalties. Any real property and facilities held under lease by the Company
and the Subsidiaries are held by them under valid, subsisting and enforceable leases with which the Company and the Subsidiaries are in compliance. 

(p) Intellectual Property. The Company and the Subsidiaries have, or have rights to use, all patents, patent
applications, trademarks, trademark applications, service marks, trade names, trade secrets, inventions, copyrights, licenses and other intellectual property rights and similar rights necessary or required for use in connection with their respective
businesses as described in the SEC Reports and which the failure to so have could have a Material Adverse Effect (collectively, the “Intellectual Property Rights”). None of, and neither the Company nor any Subsidiary has received a
notice (written or otherwise) that any of, the Intellectual Property Rights has expired, terminated or been abandoned, or is expected to expire or terminate or be abandoned, within two (2) years from the date of this Agreement. Neither the
Company nor any Subsidiary has received, since the date of the latest audited financial statements included within the SEC Reports, a written notice of a claim or otherwise has any knowledge that the Intellectual Property Rights violate or infringe
upon the rights of any Person, except as could not have or reasonably be expected to not have a Material Adverse Effect. To the knowledge of the Company, all such Intellectual Property Rights are enforceable and there is no existing infringement by
another Person of any of the Intellectual Property Rights. The Company and its Subsidiaries have taken reasonable security measures to protect the secrecy, confidentiality and value of all of their intellectual properties, except where failure to do
so could not, individually or in the aggregate, reasonably be expected to have a Material Adverse Effect. 
 (q)
Insurance. The Company and the Subsidiaries are insured by insurers of recognized financial responsibility against such losses and risks and in such amounts as are prudent and customary in the businesses in which the Company and the
Subsidiaries are engaged, including, but not limited to, directors and officers insurance coverage at least equal to the aggregate Subscription Amount. The Company has no reason to believe that it will not be able to renew its existing insurance
coverage as and when such coverage expires or to obtain similar coverage from similar insurers as may be necessary to continue its business at a cost that would not have a Material Adverse Effect. 

(r) Transactions With Affiliates and Employees. Except as disclosed in the SEC Reports, none of the officers or
directors of the Company or any Subsidiary and, to the knowledge of the Company, none of the employees of the Company or any Subsidiary is presently a party to any transaction with the Company or any Subsidiary (other than for services as employees,
officers and directors), including any contract, agreement or other arrangement providing for the furnishing of services to or by, providing for rental of real or personal property to or from, providing for the borrowing

  
 14 

 
of money from or lending of money to or otherwise requiring payments to or from any officer, director or such employee or, to the knowledge of the Company, any entity in which any officer,
director, or any such employee has a substantial interest or is an officer, director, trustee, stockholder, member or partner, in each case in excess of $120,000 other than for (i) payment of salary or consulting fees for services rendered,
(ii) reimbursement for expenses incurred on behalf of the Company and (iii) other employee benefits, including stock option agreements under any stock option plan of the Company. 

(s) Sarbanes-Oxley; Internal Accounting Controls. The Company and the Subsidiaries are in material compliance with any
and all applicable requirements of the Sarbanes-Oxley Act of 2002 that are effective as of the date hereof, and any and all applicable rules and regulations promulgated by the Commission thereunder that are effective as of the date hereof and as of
the Closing Date. The Company and the Subsidiaries maintain a system of internal accounting controls sufficient to provide reasonable assurance that: (i) transactions are executed in accordance with management’s general or specific
authorizations, (ii) transactions are recorded as necessary to permit preparation of financial statements in conformity with GAAP and to maintain asset accountability, (iii) access to assets is permitted only in accordance with
management’s general or specific authorization, and (iv) the recorded accountability for assets is compared with the existing assets at reasonable intervals and appropriate action is taken with respect to any differences. The Company and
the Subsidiaries have established disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) for the Company and the Subsidiaries and
designed such disclosure controls and procedures to ensure that information required to be disclosed by the Company in the reports it files or submits under the Exchange Act is recorded, processed, summarized and reported, within the time periods
specified in the Commission’s rules and forms. The Company’s certifying officers have evaluated the effectiveness of the disclosure controls and procedures of the Company and the Subsidiaries as of the end of the period covered by the most
recently filed periodic report under the Exchange Act (such date, the “Evaluation Date”). The Company presented in its most recently filed periodic report under the Exchange Act the conclusions of the certifying officers about the
effectiveness of the disclosure controls and procedures based on their evaluations as of the Evaluation Date. Since the Evaluation Date, there have been no changes in the internal control over financial reporting (as such term is defined in the
Exchange Act) of the Company and its Subsidiaries that have materially affected, or is reasonably likely to materially affect, the internal control over financial reporting of the Company and its Subsidiaries. 

(t) Certain Fees. Except as set forth in the Prospectus Supplement, no brokerage or finder’s fees or commissions
are or will be payable by the Company or any Subsidiary to any broker, financial advisor or consultant, finder, placement agent, investment banker, bank or other Person with respect to the transactions contemplated by the Transaction Documents. The
Purchasers shall have no obligation with respect to any fees or with respect to any claims made by or on behalf of other Persons for fees of a type contemplated in this Section that may be due in connection with the transactions contemplated by the
Transaction Documents. 

  
 15 

 (u) Investment Company. The Company is not, and is not an Affiliate
of, and immediately after receipt of payment for the Shares, the Pre-Funded Warrants, if any, and the Warrants, will not be or be an Affiliate of, an “investment company” within the meaning of the
Investment Company Act of 1940, as amended. The Company shall conduct its business in a manner so that it will not become an “investment company” subject to registration under the Investment Company Act of 1940, as amended. 

(v) Registration Rights. No Person has any right to cause the Company or any Subsidiary to effect the registration under
the Securities Act of any securities of the Company or any Subsidiary. 
 (w) Listing and Maintenance Requirements.
The Common Stock is registered pursuant to Section 12(b) or 12(g) of the Exchange Act, and the Company has taken no action designed to, or which to its knowledge is likely to have the effect of, terminating the registration of the Common Stock
under the Exchange Act nor has the Company received any notification that the Commission is contemplating terminating such registration. The Company has not, in the 12 months preceding the date hereof, received notice from any Trading Market on
which the Common Stock is or has been listed or quoted to the effect that the Company is not in compliance with the listing or maintenance requirements of such Trading Market. The Company is, and has no reason to believe that it will not in the
foreseeable future continue to be, in compliance with all such listing and maintenance requirements. The Common Stock is currently eligible for electronic transfer through the Depository Trust Company or another established clearing corporation and
the Company is current in payment of the fees to the Depository Trust Company (or such other established clearing corporation) in connection with such electronic transfer. 

(x) Application of Takeover Protections. The Company and the Board of Directors have taken all necessary action, if any,
in order to render inapplicable any control share acquisition, business combination, poison pill (including any distribution under a rights agreement) or other similar anti-takeover provision under the
Company’s certificate of incorporation (or similar charter documents) or the laws of its state of incorporation that is or could become applicable to the Purchasers as a result of the Purchasers and the Company fulfilling their obligations or
exercising their rights under the Transaction Documents, including without limitation as a result of the Company’s issuance of the Securities and the Purchasers’ ownership of the Securities. 

(y) Disclosure. Except with respect to the material terms and conditions of the transactions contemplated by the
Transaction Documents, the Company confirms that neither it nor any other Person acting on its behalf has provided any of the Purchasers or their agents or counsel with any information that it believes constitutes or might constitute material, non-public information which is not otherwise disclosed in the Prospectus Supplement or the Disclosure Package.    The Company understands and confirms that the Purchasers will rely on the
foregoing representation in effecting transactions in securities of the Company. The disclosure furnished by or on behalf of the Company to the Purchasers regarding the Company and its Subsidiaries, their respective businesses and the transactions
contemplated hereby in the Disclosure Package does not contain any untrue statement of a material fact or omit to state any material fact necessary in order to make the statements made therein, in the light of the circumstances under which they were
made, not misleading. 

  
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 (z) No Integrated Offering. Assuming the accuracy of the
Purchasers’ representations and warranties set forth in Section 3.2, neither the Company, nor any of its Affiliates, nor any Person acting on its or their behalf has, directly or indirectly, made any offers or sales of any security or
solicited any offers to buy any security, under circumstances that would cause this offering of the Securities to be integrated with prior offerings by the Company for purposes of any applicable shareholder approval provisions of any Trading Market
on which any of the securities of the Company are listed or designated. 
 (aa) Tax Status. Except for matters that
would not, individually or in the aggregate, have or reasonably be expected to result in a Material Adverse Effect, the Company and its Subsidiaries each (i) has made or filed all United States federal, state and local income and all foreign
income and franchise tax returns, reports and declarations required by any jurisdiction to which it is subject, (ii) has paid all taxes and other governmental assessments and charges that are material in amount, shown or determined to be due on
such returns, reports and declarations and (iii) has set aside on its books provision reasonably adequate for the payment of all material taxes for periods subsequent to the periods to which such returns, reports or declarations apply. There
are no unpaid taxes in any material amount claimed to be due by the taxing authority of any jurisdiction, and the officers of the Company or of any Subsidiary know of no basis for any such claim. 

(bb) Foreign Corrupt Practices. Neither the Company nor any Subsidiary, nor to the knowledge of the Company or any
Subsidiary, any agent or other person acting on behalf of the Company or any Subsidiary, has (i) directly or indirectly, used any funds for unlawful contributions, gifts, entertainment or other unlawful expenses related to foreign or domestic
political activity, (ii) made any unlawful payment to foreign or domestic government officials or employees or to any foreign or domestic political parties or campaigns from corporate funds, (iii) failed to disclose fully any contribution
made by the Company or any Subsidiary (or made by any person acting on its behalf of which the Company is aware) which is in violation of law, or (iv) violated in any material respect any provision of FCPA. 

(cc) Accountants. To the knowledge of the Company, the accounting firm certifying its financial statements in the
Disclosure Package (i) is a registered public accounting firm as required by the Exchange Act and (ii) shall express its opinion with respect to the financial statements to be included in the Company’s Annual Report for the fiscal
year ending December 31, 2018. 
 (dd) Acknowledgment Regarding Purchasers’ Purchase of Securities. The
Company acknowledges and agrees that each of the Purchasers is acting solely in the capacity of an arm’s length purchaser with respect to the Transaction Documents and the transactions contemplated thereby. The Company further acknowledges that
no 

  
 17 

 
Purchaser is acting as a financial advisor or fiduciary of the Company (or in any similar capacity) with respect to the Transaction Documents and the transactions contemplated thereby and any
advice given by any Purchaser or any of their respective representatives or agents in connection with the Transaction Documents and the transactions contemplated thereby is merely incidental to the Purchasers’ purchase of the Securities. The
Company further represents to each Purchaser that the Company’s decision to enter into this Agreement and the other Transaction Documents has been based solely on the independent evaluation of the transactions contemplated hereby by the Company
and its representatives. 
 (ee) Acknowledgment Regarding Purchaser’s Trading Activity. Anything in this
Agreement or elsewhere herein to the contrary notwithstanding (except for Sections 3.2(f) and 4.9 hereof), it is understood and acknowledged by the Company that: (i) none of the Purchasers has been asked by the Company to agree, nor has any
Purchaser agreed, to desist from purchasing or selling, long and/or short, securities of the Company, or “derivative” securities based on securities issued by the Company or to hold the Securities for any specified term; (ii) past
(prior to the date on which the Placement Agent first contacted such Investor about the Offering), or future open market or other transactions by any Purchaser, specifically including, without limitation, Short Sales or “derivative”
transactions, before or after the closing of this or future private placement transactions, may negatively impact the market price of the Company’s publicly-traded securities; (iii) any Purchaser, and counter-parties in
“derivative” transactions to which any such Purchaser is a party, directly or indirectly, presently may have a “short” position in the Common Stock (established prior to the date on which the Placement Agent first contacted such
Investor about the Offering), and (iv) each Purchaser shall not be deemed to have any affiliation with or control over any arm’s length counter-party in any “derivative” transaction. The Company further understands and
acknowledges that (y) one or more Purchasers may engage in hedging activities at various times during the period that the Securities are outstanding, and (z) such hedging activities (if any) could reduce the value of the existing
stockholders’ equity interests in the Company at and after the time that the hedging activities are being conducted. The Company acknowledges that such aforementioned hedging activities do not constitute a breach of any of the Transaction
Documents. 
 (ff) Regulation M Compliance. The Company has not, and to its knowledge no one acting on its behalf
has, (i) taken, directly or indirectly, any action designed to cause or to result in the stabilization or manipulation of the price of any security of the Company to facilitate the sale or resale of any of the Securities, (ii) sold, bid
for, purchased, or, paid any compensation for soliciting purchases of, any of the Securities, or (iii) paid or agreed to pay to any Person any compensation for soliciting another to purchase any other securities of the Company, other than, in
the case of clauses (ii) and (iii), compensation paid to the Company’s placement agent in connection with the placement of the Shares, the Pre-Funded Warrants and the Warrants. 

(gg) Office of Foreign Assets Control. Neither the Company nor any Subsidiary nor, to the Company’s knowledge, any
director, officer, agent, employee or affiliate of the Company or any Subsidiary is currently subject to any U.S. sanctions administered by the Office of Foreign Assets Control of the U.S. Treasury Department (“OFAC”). 

  
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 (hh) U.S. Real Property Holding Corporation. The Company is not and
has never been a U.S. real property holding corporation within the meaning of Section 897 of the Internal Revenue Code of 1986, as amended, and the Company shall so certify upon Purchaser’s request. 

(ii) Bank Holding Company Act. Neither the Company nor any of its Subsidiaries or Affiliates is subject to the Bank
Holding Company Act of 1956, as amended (the “BHCA”) and to regulation by the Board of Governors of the Federal Reserve System (the “Federal Reserve”). Neither the Company nor any of its Subsidiaries or Affiliates
owns or controls, directly or indirectly, five percent (5%) or more of the outstanding shares of any class of voting securities or twenty-five percent or more of the total equity of a bank or any entity that is subject to the BHCA and to regulation
by the Federal Reserve. Neither the Company nor any of its Subsidiaries or Affiliates exercises a controlling influence over the management or policies of a bank or any entity that is subject to the BHCA and to regulation by the Federal Reserve.

 (jj) Money Laundering. The operations of the Company and its Subsidiaries are and have been conducted at all times
in compliance with applicable financial record-keeping and reporting requirements of the Currency and Foreign Transactions Reporting Act of 1970, as amended, applicable money laundering statutes and applicable rules and regulations thereunder
(collectively, the “Money Laundering Laws”), and no Action or Proceeding by or before any court or governmental agency, authority or body or any arbitrator involving the Company or any Subsidiary with respect to the Money Laundering
Laws is pending or, to the knowledge of the Company or any Subsidiary, threatened. 
 3.2 Representations and Warranties of the
Purchasers. Each Purchaser, for itself and for no other Purchaser, hereby represents and warrants as of the date hereof and as of the Closing Date to the Company as follows (unless as of a specific date therein, in which case they shall be
accurate as of such date): 
 (a) Organization; Authority. Such Purchaser is either an individual or an entity duly
incorporated or formed, validly existing and in good standing under the laws of the jurisdiction of its incorporation or formation with full right, corporate, partnership limited liability company or similar power and authority to enter into and to
consummate the transactions contemplated by the Transaction Documents and otherwise to carry out its obligations hereunder and thereunder. The execution and delivery of the Transaction Documents and performance by such Purchaser of the transactions
contemplated by the Transaction Documents have been duly authorized by all necessary corporate, partnership, limited liability company or similar action, as applicable, on the part of such Purchaser. Each Transaction Document to which it is a party
has been duly executed by such Purchaser, and when delivered by such Purchaser in accordance with the terms hereof, will constitute the valid and legally binding obligation of such Purchaser, enforceable against it in accordance with its terms,
except: (i) as limited by general equitable principles and applicable bankruptcy, insolvency, reorganization, moratorium and other laws of general application affecting enforcement of creditors’ rights generally, (ii) as limited by
laws relating to the availability of specific performance, injunctive relief or other equitable remedies and (iii) insofar as indemnification and contribution provisions may be limited by applicable law. 

  
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 (b) Understandings or Arrangements. Such Purchaser is acquiring the
Securities as principal for its own account and has no direct or indirect arrangement or understandings with any other persons to distribute or regarding the distribution of such Securities (this representation and warranty not limiting such
Purchaser’s right to sell the Securities pursuant to the Registration Statement or otherwise in compliance with applicable federal and state securities laws). Such Purchaser is acquiring the Securities hereunder in the ordinary course of its
business. 
 (c) Purchaser Status. At the time such Purchaser was offered the Securities, it was, and as of the date
hereof it is either: (i) an “accredited investor” as defined in Rule 501(a)(1), (a)(2), (a)(3), (a)(7) or (a)(8) under the Securities Act or (ii) a “qualified institutional buyer” as defined in Rule 144A(a) under the
Securities Act. 
 (d) Experience of Such Purchaser. Such Purchaser, either alone or together with its
representatives, has such knowledge, sophistication and experience in business and financial matters so as to be capable of evaluating the merits and risks of the prospective investment in the Securities, and has so evaluated the merits and risks of
such investment. Such Purchaser is able to bear the economic risk of an investment in the Securities and, at the present time, is able to afford a complete loss of such investment. 

(e) Access to Information. Such Purchaser acknowledges that it has had the opportunity to review the Disclosure Package,
the Transaction Documents (including all exhibits and schedules thereto) and the SEC Reports and has been afforded, (i) the opportunity to ask such questions as it has deemed necessary of, and to receive answers from, representatives of the
Company concerning the terms and conditions of the offering of the Securities and the merits and risks of investing in the Securities; (ii) access to information about the Company and its financial condition, results of operations, business,
properties, management and prospects sufficient to enable it to evaluate its investment; and (iii) the opportunity to obtain such additional information that the Company possesses or can acquire without unreasonable effort or expense that is
necessary to make an informed investment decision with respect to the investment. Such Purchaser acknowledges and agrees that neither the Placement Agent nor any Affiliate of the Placement Agent has provided such Purchaser with any information
or advice with respect to the Securities nor is such information or advice necessary or desired. Neither the Placement Agent nor any Affiliate has made or makes any representation as to the Company or the quality of the Securities and the
Placement Agent and any Affiliate may have acquired non-public information with respect to the Company which such Purchaser agrees need not be provided to it. In connection with the issuance of the
Securities to such Purchaser, neither the Placement Agent nor any of its Affiliates has acted as a financial advisor or fiduciary to such Purchaser. 

  
 20 

 (f) Certain Transactions and Confidentiality. Other than consummating
the transactions contemplated hereunder, since the date on which the Placement Agent first contacted such Purchaser about the Offering, such Purchaser has not, nor has any Person acting on behalf of or pursuant to any understanding with such
Purchaser, directly or indirectly executed any purchases or sales, including Short Sales, of the securities of the Company. Notwithstanding the foregoing, in the case of a Purchaser that is a multi-managed investment vehicle whereby separate
portfolio managers manage separate portions of such Purchaser’s assets and the portfolio managers have no direct knowledge of the investment decisions made by the portfolio managers managing other portions of such Purchaser’s assets, the
representation set forth above shall only apply with respect to the portion of assets managed by the portfolio manager that made the investment decision to purchase the Securities covered by this Agreement. Other than to other Persons party to this
Agreement or to such Purchaser’s representatives, including, without limitation, its officers, directors, partners, legal and other advisors, employees, agents and Affiliates, such Purchaser has maintained the confidentiality of all disclosures
made to it in connection with this transaction (including the existence and terms of this transaction). Notwithstanding the foregoing, for the avoidance of doubt, nothing contained herein shall constitute a representation or warranty, or preclude
any actions, with respect to locating or borrowing shares in order to effect Short Sales or similar transactions in the future. 
 The Company acknowledges
and agrees that the representations contained in this Section 3.2 shall not modify, amend or affect such Purchaser’s right to rely on the Company’s representations and warranties contained in this Agreement or any representations and
warranties contained in any other Transaction Document or any other document or instrument executed and/or delivered in connection with this Agreement or the consummation of the transactions contemplated hereby. Notwithstanding the foregoing, for
the avoidance of doubt, nothing contained herein shall constitute a representation or warranty, or preclude any actions, with respect to locating or borrowing shares in order to effect Short Sales or similar transactions in the future (following
public disclosure of the Offering). 
 ARTICLE IV. 

OTHER AGREEMENTS OF THE PARTIES 

4.1 Pre-Funded Warrant Shares and Warrant Shares. If all or any portion of a Pre-Funded Warrant or a Warrant is exercised at a time when there is an effective registration statement to cover the issuance or resale of the Pre-Funded Warrant Shares or
the Warrant Shares, as applicable, or if the Pre-Funded Warrant or the Warrant is exercised via cashless exercise, the Pre-Funded Warrant Shares or Warrant Shares, as
applicable, issued pursuant to any such exercise shall be issued free of all legends. If at any time following the date hereof the Registration Statement (or any subsequent registration statement registering the sale or resale of the Pre-Funded Warrant Shares or the Warrant Shares, as applicable) is not effective or is not otherwise available for the sale or resale of the Pre-Funded Warrant Shares or the
Warrant Shares, as applicable, the Company shall immediately notify the holders of the Pre-Funded Warrants or the Warrants, as applicable, in writing that such registration statement is not then effective and
thereafter shall promptly notify such holders when the registration statement is effective again and available for the sale or resale of the Pre-Funded Warrant Shares or the Warrant Shares, as applicable (it
being understood and agreed that the foregoing shall not limit 

  
 21 

 
the ability of the Company to issue, or any Purchaser to sell, any of the Pre-Funded Warrant Shares or the Warrant Shares, as applicable, in compliance
with applicable federal and state securities laws). The Company shall use commercially reasonable efforts to keep a registration statement (including the Registration Statement) registering the issuance or resale of the Pre-Funded Warrant Shares and the Warrant Shares, as applicable, effective during the term of the Pre-Funded Warrants and the Warrants, as applicable. 

4.2 Furnishing of Information. Until the earlier of (i) the time that each Purchaser owns less than twenty percent (20%) of the
Shares and Pre-Funded Warrants, if any, purchased by such Purchaser hereunder and (ii) the date that is ninety (90) days after the date hereof, the Company covenants to timely file (or obtain
extensions in respect thereof and file within the applicable grace period) all reports required to be filed by the Company after the date hereof pursuant to the Exchange Act. 

4.3 Integration. The Company shall not sell, offer for sale or solicit offers to buy or otherwise negotiate in respect of any security
(as defined in Section 2 of the Securities Act) that would be integrated with the offer or sale of the Securities for purposes of the rules and regulations of any Trading Market such that it would require shareholder approval prior to the
closing of such other transaction unless shareholder approval is obtained before the closing of such subsequent transaction. 
 4.4
Securities Laws Disclosure; Publicity. The Company shall (a) by 9:00 a.m. (New York City time) on October 8, 2018 issue a press release disclosing the material terms of the transactions contemplated hereby, and (b) by 9:00 a.m.
(New York City time) on the Trading Day immediately following the date hereof, file a Current Report on Form 8-K, including the Transaction Documents as exhibits thereto, with the Commission within the time
required by the Exchange Act. The Company represents to the Purchasers that, as of the time of the issuance of such press release, it shall have publicly disclosed all material, non-public information
delivered to any of the Purchasers by the Company or any of its Subsidiaries, or any of their respective officers, directors, employees or agents in connection with the transactions contemplated by the Transaction Documents. In addition, effective
upon the issuance of such press release, the Company acknowledges and agrees that any and all confidentiality or similar obligations under any agreement, whether written or oral, between the Company, any of its Subsidiaries or any of their
respective officers, directors, employees, agents or Affiliates on the one hand, and any of the Purchasers or any of their Affiliates on the other hand, shall terminate. No Purchaser shall issue any press release nor otherwise make any public
statement without the prior consent of the Company, which consent shall not unreasonably be withheld or delayed, except if such disclosure is required by law, in which case the disclosing party shall promptly provide the other party with prior
notice of such public statement or communication. Notwithstanding the foregoing, the Company shall not publicly disclose the name of any Purchaser, or include the name of any Purchaser in any filing with the Commission or any regulatory agency or
Trading Market, without the prior written consent of such Purchaser, except (a) as required by federal securities law in connection with the filing of final Transaction Documents with the Commission and (b) to the extent such disclosure is
required by law or Trading Market regulations, in which case the Company shall provide the Purchasers with prior notice of such disclosure permitted under this clause (b). 

  
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 4.5 Shareholder Rights Plan. No claim will be made or enforced by the Company or,
with the consent of the Company, any other Person, that any Purchaser is an “Acquiring Person” under any control share acquisition, business combination, poison pill (including any distribution under a rights agreement) or similar
anti-takeover plan or arrangement in effect or hereafter adopted by the Company, or that any Purchaser could be deemed to trigger the provisions of any such plan or arrangement, solely by virtue of receiving Securities under this Agreement. 

4.6 Non-Public Information. Except with respect to the material terms and conditions of the
transactions contemplated by the Transaction Documents, which shall be disclosed pursuant to Section 4.4, the Company covenants and agrees that neither it, nor any other Person acting on its behalf will provide any Purchaser or its agents or
counsel with any information that constitutes, or the Company reasonably believes constitutes, material non-public information, unless prior thereto such Purchaser shall have consented to the receipt of such
information and agreed with the Company to keep such information confidential. The Company understands and confirms that each Purchaser shall be relying on the foregoing covenant in effecting transactions in securities of the Company. To the extent
that the Company delivers any material, non-public information to a Purchaser without such Purchaser’s consent, the Company hereby covenants and agrees that such Purchaser shall not have any duty of
confidentiality to the Company, any of its Subsidiaries, or any of their respective officers, directors, agents, employees or Affiliates, or a duty to the Company, any of its Subsidiaries or any of their respective officers, directors, agents,
employees or Affiliates not to trade on the basis of, such material, non-public information, provided that the Purchaser shall remain subject to applicable law. To the extent that any notice provided pursuant
to any Transaction Document constitutes, or contains, material, non-public information regarding the Company or any Subsidiaries, the Company shall simultaneously file such notice with the Commission pursuant
to a Current Report on Form 8-K. The Company understands and confirms that each Purchaser shall be relying on the foregoing covenants in this Section 4.5 in effecting transactions in securities of the
Company. 
 4.7 Use of Proceeds. The Company shall use the net proceeds from the sale of the Securities hereunder for working
capital, the conduct of its business as described in the Disclosure Package and other general corporate purposes and shall not use such proceeds: (a) for the satisfaction of any portion of the Company’s debt (other than payment of trade
payables and other liabilities arising in the ordinary course of the Company’s business and prior practices), (b) for the redemption of any Common Stock or Common Stock Equivalents, (c) for the settlement of any outstanding litigation or
(d) in violation of FCPA or OFAC regulations. 
 4.8 Indemnification of Purchasers. Subject to the provisions of this
Section 4.7, the Company will indemnify and hold each Purchaser and its directors, officers, shareholders, members, partners, employees and agents (and any other Persons with a functionally equivalent role of a Person holding such titles
notwithstanding a lack of such title or any other title), each Person who controls such Purchaser (within the meaning of Section 15 of the Securities Act and Section 20 of the Exchange Act), and the directors, officers, shareholders,
agents, members, partners or employees (and any other Persons with a functionally equivalent role of a Person holding such titles notwithstanding a lack of such title or any other title) of such controlling persons (each, a “Purchaser
Party”) harmless from any and all losses, liabilities, obligations, claims, contingencies, damages, costs and expenses, including all judgments, amounts paid in settlements, court costs and reasonable attorneys’ fees and costs of
investigation that any such 

  
 23 

 
Purchaser Party may suffer or incur as a result of or relating to (a) any breach of any of the representations, warranties, covenants or agreements made by the Company in this Agreement or
in the other Transaction Documents or (b) any action instituted against the Purchaser Parties in any capacity, or any of them or their respective Affiliates, by any stockholder of the Company who is not an Affiliate of such Purchaser Party and
not another Purchaser or an Affiliate of such Purchaser, with respect to any of the transactions contemplated by the Transaction Documents (unless such action is solely based upon a material breach of such Purchaser Party’s representations,
warranties or covenants under the Transaction Documents or any agreements or understandings such Purchaser Party may have with any such stockholder or any violations by such Purchaser Party of state or federal securities laws or any conduct by such
Purchaser Party which is finally judicially determined to constitute fraud, gross negligence or willful misconduct). If any action shall be brought against any Purchaser Party in respect of which indemnity may be sought pursuant to this Agreement,
such Purchaser Party shall promptly notify the Company in writing, and the Company shall have the right to assume the defense thereof with counsel of its own choosing reasonably acceptable to the Purchaser Party. Any Purchaser Party shall have the
right to employ separate counsel in any such action and participate in the defense thereof, but the fees and expenses of such counsel shall be at the expense of such Purchaser Party except to the extent that (i) the employment thereof has been
specifically authorized by the Company in writing, (ii) the Company has failed after a reasonable period of time to assume such defense and to employ counsel or (iii) in such action there is, in the reasonable opinion of counsel, a
material conflict on any material issue between the position of the Company and the position of such Purchaser Party, in which case the Company shall be responsible for the reasonable fees and expenses of no more than one such separate counsel. The
Company will not be liable to any Purchaser Party under this Agreement (y) for any settlement by a Purchaser Party effected without the Company’s prior written consent, which shall not be unreasonably withheld or delayed; or (z) to
the extent, but only to the extent that a loss, claim, damage or liability is attributable to any Purchaser Party’s breach of any of the representations, warranties, covenants or agreements made by such Purchaser Party in this Agreement or in
the other Transaction Documents. The indemnification required by this Section 4.7 shall be made by periodic payments of the amount thereof during the course of the investigation or defense, as and when bills are received or are incurred. The
indemnity agreements contained herein shall be in addition to any cause of action or similar right of any Purchaser Party against the Company or others and any liabilities the Company may be subject to pursuant to law. 

Notwithstanding anything in this Agreement to the contrary, the Company shall not be liable to any Purchaser for any loss incurred as a result of a reduction
in the Company’s stock price caused by selling activity by any of the Purchasers with respect to the Company’s securities. 
 4.9
Reservation of Common Stock. As of the date hereof, the Company has reserved and the Company shall continue to reserve and keep available at all times, free of preemptive rights, a sufficient number of shares of Common Stock for the purpose
of enabling the Company to issue Shares pursuant to this Agreement and Pre-Funded Warrant Shares and Warrant Shares pursuant to any exercise of the Pre-Funded Warrants
and the Warrants, as applicable. 

  
 24 

 4.10 Listing of Common Stock. The Company hereby agrees to use commercially
reasonable efforts to maintain the listing or quotation of the Common Stock on the Trading Market on which it is currently listed, and concurrently with the Closing, the Company shall apply to list or quote all of the Shares, the Pre-Funded Warrant Shares and the Warrant Shares on such Trading Market and promptly secure the listing of all of the Shares, the Pre-Funded Warrant Shares and the Warrant
Shares on such Trading Market. The Company further agrees, if the Company applies to have the Common Stock traded on any other Trading Market, it will then include in such application all of the Shares, the
Pre-Funded Warrant Shares and the Warrant Shares, and will take such other action as is necessary to cause all of the Shares, the Pre-Funded Warrant Shares and the
Warrant Shares to be listed or quoted on such other Trading Market as promptly as possible. The Company will then take all action reasonably necessary to continue the listing and trading of its Common Stock on a Trading Market and will comply in all
respects with the Company’s reporting, filing and other obligations under the bylaws or rules of the Trading Market. The Company agrees to use commercially reasonable efforts to maintain the eligibility of the Common Stock for electronic
transfer through the Depository Trust Company or another established clearing corporation, including, without limitation, by timely payment of fees to the Depository Trust Company or such other established clearing corporation in connection with
such electronic transfer. 
 4.11 Certain Transactions and Confidentiality. Each Purchaser, severally and not jointly with the other
Purchasers, covenants that neither it nor any Affiliate acting on its behalf or pursuant to any understanding with it will execute any purchases or sales, including Short Sales of any of the Company’s securities during the period commencing
with the execution of this Agreement and ending at such time that the transactions contemplated by this Agreement are first publicly announced pursuant to the initial press release as described in Section 4.3. Each Purchaser, severally and
not jointly with the other Purchasers, covenants that until such time as the transactions contemplated by this Agreement are publicly disclosed by the Company pursuant to the initial press release as described in Section 4.3, such Purchaser
will maintain the confidentiality of the existence and terms of this transaction and the information included in the Disclosure Package. Notwithstanding the foregoing, and notwithstanding anything contained in this Agreement to the contrary,
the Company expressly acknowledges and agrees that (i) no Purchaser makes any representation, warranty or covenant hereby that it will not engage in effecting transactions in any securities of the Company after the time that the transactions
contemplated by this Agreement are first publicly announced pursuant to the initial press release as described in Section 4.3, (ii) no Purchaser shall be restricted or prohibited from effecting any transactions in any securities of the Company
in accordance with applicable securities laws from and after the time that the transactions contemplated by this Agreement are first publicly announced pursuant to the initial press release as described in Section 4.3 and (iii) no
Purchaser shall have any duty of confidentiality or duty not to trade in the securities of the Company to the Company or its Subsidiaries after the issuance of the initial press release as described in Section 4.3. Notwithstanding the
foregoing, in the case of a Purchaser that is a multi-managed investment vehicle whereby separate portfolio managers manage separate portions of such Purchaser’s assets and the portfolio managers have no direct knowledge of the investment
decisions made by the portfolio managers managing other portions of such Purchaser’s assets, the covenant set forth above shall only apply with respect to the portion of assets managed by the portfolio manager that made the investment decision
to purchase the Securities covered by this Agreement. 
 4.12 Capital Changes. Until the one year anniversary of the Closing Date,
the Company shall not undertake a reverse or forward stock split or reclassification of the Common Stock without the prior written consent of the Purchasers holding a majority in interest of the Shares and
Pre-Funded Warrants. 

  
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 4.13 Termination of Certain Obligations. The obligations of the Company pursuant to
Sections 4.1, 4.5, 4.6, 4.10 and 4.11 shall terminate, with respect to each Purchaser, on the earlier of (i) the time that each Purchaser beneficially owns less than twenty percent (20%) of the Shares and
Pre-Funded Warrants, if any, purchased by such Purchaser hereunder, net of Short Sales and any “derivative” securities acquired by such Purchaser (the “Minimum Ownership Amount”),
and (ii) the date that is ninety (90) days after the date hereof. Upon reasonable request of the Company, each Purchaser shall provide to the Company a representation, which may be by e-mail, as to
whether or not such Purchaser continues to own the Minimum Ownership Amount. 
 4.14 Subsequent Equity Sales. From the date hereof until
sixty (60) days after the Closing Date, neither the Company nor any Subsidiary shall issue, enter into any agreement to issue or announce the issuance or proposed issuance of any shares of Common Stock or Common Stock Equivalents. 

ARTICLE V. 
 MISCELLANEOUS

 5.1 Termination. This Agreement may be terminated by any Purchaser, as to such Purchaser’s obligations hereunder only
and without any effect whatsoever on the obligations between the Company and the other Purchasers, by written notice to the other parties, if the Closing has not been consummated on or before October 10, 2018; provided, however,
that no such termination will affect the right of any party to sue for any breach by any other party (or parties). 
 5.2 Fees and
Expenses. Except as expressly set forth in the Transaction Documents to the contrary, each party shall pay the fees and expenses of its advisers, counsel, accountants and other experts, if any, and all other expenses incurred by such party
incident to the negotiation, preparation, execution, delivery and performance of this Agreement. The Company shall pay all Transfer Agent fees (including, without limitation, any fees required for same-day
processing of any instruction letter delivered by the Company), stamp taxes and other taxes and duties levied in connection with the delivery of any Securities to the Purchasers. 

5.3 Entire Agreement. The Transaction Documents, together with the exhibits and schedules thereto, the Prospectus and the Prospectus
Supplement, contain the entire understanding of the parties with respect to the subject matter hereof and thereof and supersede all prior agreements and understandings, oral or written, with respect to such matters, which the parties acknowledge
have been merged into such documents, exhibits and schedules. 
 5.4 Notices. Any and all notices or other communications or
deliveries required or permitted to be provided hereunder shall be in writing and shall be deemed given and effective on the earliest of: (a) the time of transmission, if such notice or communication is delivered via email attachment at the
email address as set forth on the signature pages attached hereto at or prior to 5:30 p.m. (New York City time) on a Trading Day, (b) the next Trading Day after the 

  
 26 

 
date of transmission, if such notice or communication is delivered via email attachment at the email address as set forth on the signature pages attached hereto on a day that is not a Trading Day
or later than 5:30 p.m. (New York City time) on any Trading Day, (c) the second (2nd)Trading Day following the date of mailing, if sent by U.S. nationally recognized overnight courier service
or (d) upon actual receipt by the party to whom such notice is required to be given. The address for such notices and communications shall be as set forth on the signature pages attached hereto. To the extent that any notice provided pursuant
to any Transaction Document constitutes, or contains, material, non-public information regarding the Company or any Subsidiaries, the Company shall simultaneously file such notice with the Commission pursuant
to a Current Report on Form 8-K. 
 5.5 Amendments; Waivers. No provision of this Agreement
may be waived, modified, supplemented or amended except in a written instrument signed, in the case of an amendment, by the Company and Purchasers which purchased a majority of the Shares and the Pre-Funded
Warrants, if any, based on the initial Subscription Amounts hereunder or, in the case of a waiver, by the party against whom enforcement of any such waived provision is sought, provided that if any amendment, modification or waiver
disproportionately and adversely impacts a Purchaser (or group of Purchasers) in any material respect, the consent of such disproportionately impacted Purchaser (or group of Purchasers) shall also be required. No waiver of any default with respect
to any provision, condition or requirement of this Agreement shall be deemed to be a continuing waiver in the future or a waiver of any subsequent default or a waiver of any other provision, condition or requirement hereof except to the extent
expressly stated in such waiver, nor shall any delay or omission of any party to exercise any right hereunder in any manner impair the exercise of any such right. Any proposed amendment or waiver that disproportionately, materially and adversely
affects the rights and obligations of any Purchaser relative to the comparable rights and obligations of the other Purchasers shall require the prior written consent of such adversely affected Purchaser. Any amendment effected in accordance with
this Section 5.5 shall be binding upon each Purchaser and holder of Securities and the Company. 
 5.6 Headings. The headings
herein are for convenience only, do not constitute a part of this Agreement and shall not be deemed to limit or affect any of the provisions hereof. 

5.7 Successors and Assigns. This Agreement shall be binding upon and inure to the benefit of the parties and their successors and
permitted assigns. The Company may not assign this Agreement or any rights or obligations hereunder without the prior written consent of each Purchaser (other than by merger). Any Purchaser may assign any or all of its rights under this Agreement to
any Person to whom such Purchaser assigns or transfers any Securities, provided that such transferee agrees in writing to be bound, with respect to the transferred Securities, by the provisions of the Transaction Documents that apply to the
“Purchasers.” 
 5.8 No Third-Party Beneficiaries. This Agreement is intended for the benefit of the parties hereto and
their respective successors and permitted assigns and is not for the benefit of, nor may any provision hereof be enforced by, any other Person, except as otherwise set forth in Section 4.7 and this Section 5.8. 

  
 27 

 5.9 Governing Law. All questions concerning the construction, validity, enforcement
and interpretation of the Transaction Documents 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 Agreement and any other Transaction Documents (whether brought against a party hereto or its 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 (including with respect to the enforcement
of any of the Transaction Documents), and hereby irrevocably waives, and agrees not to assert in any Action or Proceeding, any claim that it is not personally subject to the jurisdiction of any such court, that such Action or Proceeding is improper
or is an inconvenient venue for such Proceeding. Each party hereby irrevocably waives personal service of process and consents to process being served in any such 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 Agreement 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 any party shall commence an Action or Proceeding to enforce any provisions of the Transaction Documents, then, in addition to the
obligations of the Company under Section 4.7, the prevailing party in such Action or Proceeding shall be reimbursed by the non-prevailing party for its reasonable attorneys’ fees and other costs and
expenses incurred with the investigation, preparation and prosecution of such Action or Proceeding. 
 5.10 Survival. The
representations and warranties contained herein shall survive the Closing and the delivery of the Shares, the Pre-Funded Warrants and the Warrants. 

5.11 Execution. This Agreement may be executed in two or more counterparts, all of which when taken together shall be considered one
and the same agreement and shall become effective when counterparts have been signed by each party and delivered to each other party, it being understood that the parties need not sign the same counterpart. In the event that any signature is
delivered by facsimile transmission or by e-mail delivery of a “.pdf” format data file, such signature shall create a valid and binding obligation of the party executing (or on whose behalf such
signature is executed) with the same force and effect as if such facsimile or “.pdf” signature page were an original thereof. 

5.12 Severability. If any term, provision, covenant or restriction of this Agreement is held by a court of competent jurisdiction to be
invalid, illegal, void or unenforceable, the remainder of the terms, provisions, covenants and restrictions set forth herein shall remain in full force and effect and shall in no way be affected, impaired or invalidated, and the parties hereto shall
use their commercially reasonable efforts to find and employ an alternative means to achieve the same or substantially the same result as that contemplated by such term, provision, covenant or restriction. It is hereby stipulated and declared to be
the intention of the parties that they would have executed the remaining terms, provisions, covenants and restrictions without including any of such that may be hereafter declared invalid, illegal, void or unenforceable. 

  
 28 

 5.13 Rescission and Withdrawal Right. Notwithstanding anything to the contrary
contained in (and without limiting any similar provisions of) any of the other Transaction Documents, whenever any Purchaser exercises a right, election, demand or option under a Transaction Document and the Company does not timely perform its
related obligations within the periods therein provided, then such Purchaser may rescind or withdraw, in its sole discretion from time to time upon written notice to the Company, any relevant notice, demand or election in whole or in part without
prejudice to its future actions and rights. 
 5.14 Replacement of Securities. If any certificate or instrument evidencing any
Securities is mutilated, lost, stolen or destroyed, the Company shall issue or cause to be issued in exchange and substitution for and upon cancellation thereof (in the case of mutilation), or in lieu of and substitution therefor, a new certificate
or instrument, but only upon receipt of evidence reasonably satisfactory to the Company of such loss, theft or destruction. The applicant for a new certificate or instrument under such circumstances shall also pay any reasonable third-party costs
(including customary indemnity) associated with the issuance of such replacement Securities. 
 5.15 Remedies. In addition to being
entitled to exercise all rights provided herein or granted by law, including recovery of damages, each of the Purchasers and the Company will be entitled to specific performance under the Transaction Documents. The parties agree that monetary
damages may not be adequate compensation for any loss incurred by reason of any breach of obligations contained in the Transaction Documents and hereby agree to waive and not to assert in any Action for specific performance of any such obligation
the defense that a remedy at law would be adequate. 
 5.16 Payment Set Aside. To the extent that the Company makes a payment or
payments to any Purchaser pursuant to any Transaction Document or a Purchaser enforces or exercises its rights thereunder, and such payment or payments or the proceeds of such enforcement or exercise or any part thereof are subsequently invalidated,
declared to be fraudulent or preferential, set aside, recovered from, disgorged by or are required to be refunded, repaid or otherwise restored to the Company, a trustee, receiver or any other Person under any law (including, without limitation, any
bankruptcy law, state or federal law, common law or equitable cause of action), then to the extent of any such restoration the obligation or part thereof originally intended to be satisfied shall be revived and continued in full force and effect as
if such payment had not been made or such enforcement or setoff had not occurred. 
 5.17 Independent Nature of Purchasers’
Obligations and Rights. The obligations of each Purchaser under any Transaction Document are several and not joint with the obligations of any other Purchaser, and no Purchaser shall be responsible in any way for the performance or non-performance of the obligations of any other Purchaser under any Transaction Document. Nothing contained herein or in any other Transaction Document, and no action taken by any Purchaser pursuant hereto or
thereto, shall be deemed to constitute the Purchasers as a partnership, an association, a joint venture or any other kind of entity, or create a presumption that the Purchasers are in any way acting in concert or as a group with respect to such
obligations 

  
 29 

 
or the transactions contemplated by the Transaction Documents. Each Purchaser shall be entitled to independently protect and enforce its rights including, without limitation, the rights arising
out of this Agreement or out of the other Transaction Documents, and it shall not be necessary for any other Purchaser to be joined as an additional party in any Proceeding for such purpose. Each Purchaser has been represented by its own separate
legal counsel in its review and negotiation of the Transaction Documents. For reasons of administrative convenience only, each Purchaser and its respective counsel have chosen to communicate with the Company through LS. LS does not represent any of
the Purchasers. The Company has elected to provide all Purchasers with the same terms and Transaction Documents for the convenience of the Company and not because it was required or requested to do so by any of the Purchasers. It is expressly
understood and agreed that each provision contained in this Agreement and in each other Transaction Document is between the Company and a Purchaser, solely, and not between the Company and the Purchasers collectively and not between and among the
Purchasers. Notwithstanding anything to the contrary in the foregoing, each of the Purchasers has been advised, and is being advised by this Agreement, to consult with an attorney before executing this Agreement, and each Purchaser has consulted (or
had an opportunity to consult) with counsel of such Purchaser’s choice concerning the terms and conditions of this Agreement and the other Transaction Documents for a reasonable period of time prior to the execution hereof and thereof. 

5.18 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. 

5.19 Construction. The parties agree that each of them and/or their respective counsel have reviewed and had an opportunity to revise
the Transaction Documents and, therefore, the normal rule of construction to the effect that any ambiguities are to be resolved against the drafting party shall not be employed in the interpretation of the Transaction Documents or any amendments
thereto. In addition, each and every reference to share prices and shares of Common Stock in any Transaction Document shall be subject to adjustment for reverse and forward stock splits, stock dividends, stock combinations and other similar
transactions of the Common Stock that occur after the date of this Agreement. 
 5.20 WAIVER OF JURY TRIAL. IN
ANY ACTION, SUIT, OR PROCEEDING IN ANY JURISDICTION BROUGHT BY ANY PARTY AGAINST ANY OTHER PARTY, THE PARTIES EACH KNOWINGLY AND INTENTIONALLY, TO THE GREATEST EXTENT PERMITTED BY APPLICABLE LAW, HEREBY ABSOLUTELY, UNCONDITIONALLY, IRREVOCABLY AND
EXPRESSLY WAIVES FOREVER TRIAL BY JURY.  
 (Signature Pages Follow) 

  
 30 

 IN WITNESS WHEREOF, the parties hereto have caused this Securities Purchase Agreement to be
duly executed by their respective authorized signatories as of the date first indicated above. 
  

			
	ALTIMMUNE, INC.	  	 Address for Notice:
  

910 Clopper Road, Suite 201S
 Gaithersburg, Maryland
20878

		
	 By:
                                         
                                         
      
        Name:

       Title:
	  	E-Mail: enright@altimmune.com

 [REMAINDER OF PAGE INTENTIONALLY LEFT BLANK 

SIGNATURE PAGE FOR PURCHASER FOLLOWS] 

  
 31 

 PURCHASER SIGNATURE PAGES TO SECURITIES PURCHASE AGREEMENT 

IN WITNESS WHEREOF, the undersigned have caused this Securities Purchase Agreement to be duly executed by their respective authorized
signatories as of the date first indicated above. 
  

	
	 Name of Purchaser:
                                         
                                         
                                      

	
	 Signature of Authorized Signatory of Purchaser:
                                         
                                 

	
	 Name of Authorized Signatory:
                                         
                                         
                   

	
	 Title of Authorized Signatory:
                                         
                                         
                     

	
	 Email Address of Authorized Signatory:
                                         
                                         
     

	
	 Address for Notice to Purchaser:
                                         
                                         
                 

 Address for Delivery of Securities to Purchaser (if not same as address for notice): 

 

	
	 Common Unit Subscription Amount:
$                                         
   

	
	 Common Units:
                                    

	
	 Pre-Funded Unit Subscription Amount:
$                                        

	
	 Pre-Funded Units:
                                    

	
	 EIN Number:
                                         
    

 ☐ Notwithstanding anything contained in this Agreement to the contrary, by checking this box (i) the obligations of
the above-signed to purchase the securities set forth in this Agreement to be purchased from the Company by the above-signed, and the obligations of the Company to sell such securities to the above-signed, shall be unconditional and all conditions
to Closing shall be disregarded, (ii) the Closing shall occur on the second (2nd) Trading Day following the date of this Agreement and (iii) any condition to Closing contemplated by this
Agreement (but prior to being disregarded by clause (i) above) that required delivery by the Company or the above-signed of any agreement, instrument, certificate or the like or purchase price (as applicable) shall no longer be a condition and
shall instead be an unconditional obligation of the Company or the above-signed (as applicable) to deliver such agreement, instrument, certificate or the like or purchase price (as applicable) to such other party on the Closing Date. 

  
 32 

 [SIGNATURE PAGES CONTINUE] 

  
 33 

 Exhibit A 

Form of Pre-Funded Warrant 

  
 34 

 Exhibit B 

Form of Warrant 

  
 35

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