Exhibit 4.2


 


NEITHER THESE SECURITIES NOR THE SECURITIES
ISSUABLE UPON EXERCISE OF THESE SECURITIES HAVE BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED (THE “SECURITIES
ACT”), OR APPLICABLE STATE SECURITIES LAWS. THE SECURITIES MAY NOT BE OFFERED FOR SALE, SOLD, TRANSFERRED OR ASSIGNED (I)
IN THE ABSENCE OF (A) AN EFFECTIVE REGISTRATION STATEMENT FOR THE SECURITIES UNDER THE SECURITIES ACT OR (B) AN AVAILABLE EXEMPTION
FROM, OR IN A TRANSACTION NOT SUBJECT TO, THE REGISTRATION REQUIREMENTS OF THE SECURITIES ACT AND IN ACCORDANCE WITH APPLICABLE
STATE SECURITIES LAWS OR BLUE SKY LAWS AS EVIDENCED BY A LEGAL OPINION OF COUNSEL REASONABLY SATISFACTORY TO THE COMPANY AND ITS
TRANSFER AGENT OR (II) UNLESS SOLD PURSUANT TO RULE 144 UNDER THE SECURITIES ACT. NOTWITHSTANDING THE FOREGOING, THE SECURITIES
MAY BE PLEDGED IN CONNECTION WITH A BONA FIDE MARGIN ACCOUNT OR OTHER LOAN OR FINANCING ARRANGEMENT SECURED BY THE SECURITIES.


 


[FORM OF WARRANT]


 


IDERA PHARMACEUTICALS,
INC.


 


WARRANT TO PURCHASE
COMMON STOCK


 


Warrant No.: [Ÿ]


Number of Shares of Common Stock:
[                    ]


Date of Issuance: [Ÿ],
2020 (“Issuance Date”)


Expiration Date: [Ÿ],
2023 (“Expiration Date”)


 


Idera Pharmaceuticals,
Inc., a Delaware corporation (the “Company”), hereby certifies that, for good and valuable consideration, the
receipt and sufficiency of which are hereby acknowledged, , 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 the next business day after the Issuance Date, but not after 11:59 p.m., New York time,
on the Expiration Date, the Warrant Shares (as defined below). 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 14. This Warrant is one of the Warrants to Purchase
Common Stock (the “Warrants”) issued in connection with the transactions contemplated by that certain Securities
Purchase Agreement, dated as of [__], 2020 (the “Subscription Date”) by and between the Company, the holder
and the other purchasers set forth on the schedule of purchasers thereto (the “Securities Purchase Agreement”).


 






     


     


    

 


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(e)),
this Warrant may be exercised by the Holder at any time or times on or after the Issuance 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 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 (“FAST”), 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 and at its own
expense, issue and deliver to the Holder (or its designee) a new Warrant (in accordance with Section 6(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 shares of Common Stock are to be issued upon
the exercise of this Warrant, but rather the number of shares of Common Stock to be issued shall be rounded down 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) Company’s
Failure to Timely Deliver Securities. 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 (other than a failure caused by incorrect or incomplete
information provided by the Holder to the Company), 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 the Holder $1,000. The Holder shall
provide the Company written notice within three (3) Trading Days after the occurrence of a Buy-In, 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.


 






     


     


    

 


(c) Cashless
Exercise. Notwithstanding anything contained herein to the contrary, if a registration statement covering the issuance or resale
of the shares of Common Stock that constitute Warrant Shares is not available for the issuance or resale, as applicable, 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 × B) - (A × C)


                B



For purposes of the foregoing
formula:


 


	A=	 	the total number of shares of Common Stock with respect to which this Warrant is then being exercised.
	 	 
	B=	 	as applicable: (i) the Closing Sale Price of the Common Stock on the Trading Day immediately preceding the date of the applicable Exercise Notice if such Exercise Notice is (1) both executed and delivered pursuant to Section 1(a) hereof on a day that is not a Trading Day or (2) both executed and delivered pursuant to Section 1(a) hereof on a Trading Day prior to the opening of “regular trading hours” (as defined in Rule 600(b)(64) of Regulation NMS promulgated under the federal securities laws) on such Trading Day, (ii) at the option of the Holder, either (y) the Weighted Average Price on the Trading Day immediately preceding the date of the applicable Notice of Exercise or (z) the Bid Price of the Common Stock as of the time of the Holder’s execution of the applicable Exercise Notice if such Exercise Notice is executed during “regular trading hours” on a Trading Day and is delivered within two (2) hours thereafter (including until two (2) hours after the close of “regular trading hours” on a Trading Day) pursuant to Section 1(a) hereof or (iii) the Closing Sale Price of the Common Stock on the date of the applicable Exercise Notice if the date of such Exercise Notice is a Trading Day and such Exercise Notice is both executed and delivered pursuant to Section 1(a) hereof after the close of “regular trading hours” on such Trading Day.
	 	 	 
	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 “Securities Act”), 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(c).


 


(d) 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 9.


 






     


     


    

 


(e) 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 immediately prior to or after giving effect to such exercise, the Holder together with the other Attribution Parties
collectively would beneficially own in excess of 19.99% (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(e). For purposes of this Section 1(e), beneficial ownership shall be
calculated in accordance with Section 13(d) of the Securities Exchange Act of 1934, as amended (the “Exchange
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(e) applies, the
determination of whether this Warrant is exercisable (in relation to other securities owned by the Holder together with any
Affiliates and Attribution Parties) and of which portion of this Warrant is exercisable shall be in the sole discretion of
the Holder, and the 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 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(e), to exceed the Maximum Percentage, the Holder must notify the Company of a reduced number of 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 or oral
request of the Holder, the Company shall within one (1) Business Day confirm orally and in writing or by electronic mail
to the Holder the number of shares of Common Stock then outstanding. In any case, the number of outstanding shares of Common
Stock shall be determined after giving effect to the conversion or exercise of securities of the Company, including this
Warrant, by the Holder 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 Exchange 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 as specified in such notice not in excess of 19.99%;
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 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 Exchange 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(e) 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(e) 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.


 






     


     


    

 


(f) Required
Reserve Amount. Subject to Section 1(g) below, 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(f) 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 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).


 


(g) 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 120 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.


 


2.     ADJUSTMENT
OF EXERCISE PRICE AND NUMBER OF WARRANT SHARES UPON SUBDIVISION OR COMBINATION OF COMMON STOCK.


 


(a) Subdivisions
or Combinations. If the Company at any time on or after the Issuance 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 applicable Exercise Price in effect immediately prior to such subdivision will be proportionately reduced and
the number of the applicable 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 applicable Exercise Price in effect immediately prior to such
combination will be proportionately increased and the number of the applicable Warrant Shares will be proportionately
decreased. Any adjustment under this Section 2(a) shall become effective at the close of business on the date the
subdivision or combination becomes effective.


 






     


     


    

 


(b) Rights
Upon Distribution of Assets. In addition to any adjustments pursuant to the other subsections of this Section 2, if, on
or after the Issuance 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).


 


(c) Purchase
Rights. In addition to any adjustments pursuant to the other subsections of Section 2 above, if at any time on or
after the Issuance 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).


 






     


     


    

 


(d) Fundamental
Transactions. At any time while this Warrant remains outstanding, 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 3, 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). 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(e)
hereof, the Holder may elect, at its sole option, by delivery of written notice to the Company to waive this Section 3
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) 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 3 shall apply similarly and equally to successive Fundamental Transactions and Corporate Events.
Notwithstanding the foregoing, in the event of a Change of Control (other than a Change of Control which was not approved by
the Board of Directors, as to which this right shall not apply), at the request of the Holder delivered before the 30th day
after such Change of Control, the Company (or the Successor Entity) shall purchase this Warrant from the Holder by paying to
the Holder, within five (5) Business Days after such request (or, if later, on the effective date of the Change of
Control), an amount equal to the Black Scholes Value of the remaining unexercised portion of this Warrant on the effective
date of such Change of Control, payable in cash; provided, that if the applicable Change of Control was not approved by the
Company’s Board of Directors, the Black-Scholes Value of the remaining unexercised portion of this Warrant shall be
payable at the option of the Company in either (x) Common Stock, whereby the Company would be continually obligated to
actively settle shares of Common Stock in the event insufficient authorized shares of Common Stock were available (or
corresponding Corporate Event Consideration, as applicable) valued at the value of the consideration received by the
shareholders in such Change of Control or (y) cash.


 






     


     


    

 


3.     NONCIRCUMVENTION.
The Company hereby covenants and agrees that the Company will not, by amendment of its certificate of incorporation or by-laws, 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 applicable 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).


 


4.     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 Company, whether such liabilities are asserted by the Company
or by creditors of the Company.


 


5.     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 5(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 5(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 5(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 5(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 5(a)
or Section 5(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.


 


6.     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 6 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 7 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:


 


Idera Pharmaceuticals, Inc.


505 Eagleview Blvd., Suite
212 


Exton, Pennsylvania 19341


Attn: Chief Financial Officer


 


with copies to:


 


Morgan, Lewis & Bockius
LLP


1701 Market Street


Philadelphia, Pennsylvania
19103-2921


Attn: Joanne R. Soslow, Esq.


Email: joanne.soslow@morganlewis.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.


 


7.     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 the Holder.


 


8.     GOVERNING
LAW; 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. 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.


 






     


     


    

 


9.     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.


 


10.   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 seek an injunction restraining any breach, without the necessity of showing economic
loss and without any bond or other security being required.


 


11.   TRANSFER.
Subject to compliance with applicable federal and state securities laws, this Warrant and the Warrant Shares may be offered for
sale, sold, transferred, pledged or assigned without the consent of the Company.


 






     


     


    

 


12.   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.


 


13.   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.   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.


 


(b) “Attribution
Parties” means, collectively, the Holder (together with the Holder’s Affiliates, and any other persons acting as
a group together with the Holder or any of the Holder’s Affiliates. 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 9. All such determinations shall be appropriately adjusted for any stock dividend, stock split, stock
combination or other similar transaction during such period.


 






     


     


    

 


(d) “Black
Scholes Value” means the value of this Warrant based on the Black-Scholes Option Pricing Model obtained from the “OV”
function on Bloomberg determined as of the day immediately following the first public announcement of the applicable Change of
Control, or, if the Change of Control is not publicly announced, the date the Change of Control 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 60%, (iii) the underlying price per share
used in such calculation shall be the greater of (A) the sum of the price per share being offered in cash, if any, plus the
per share value of any non-cash consideration, if any, being offered in such Change of Control and (B) the greater
of (x) the last Weighted Average Price immediately prior to the public announcement of such Change of Control and (y) the
last Weighted Average Price immediately prior to the consummation of such Change of Control, (iv) a zero cost of borrow and
(v) a 360 day annualization factor.


 


(e) “Bloomberg”
means Bloomberg Financial Markets.


 


(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) “Change
of Control” means any Fundamental Transaction other than (i) any reorganization, recapitalization or reclassification
of the Common Stock in which holders of the Company’s voting power immediately prior to such reorganization, recapitalization
or reclassification continue after such reorganization, recapitalization or reclassification to hold publicly traded securities
and, directly or indirectly, are, in all material respects, the holders of the voting power of the surviving entity (or entities
with the authority or voting power to elect the members of the board of directors (or their equivalent if other than a corporation)
of such entity or entities) after such reorganization, recapitalization or reclassification, (ii) pursuant to a migratory
merger effected solely for the purpose of changing the jurisdiction of incorporation of the Company or (iii) a merger in connection
with a bona fide acquisition by the Company of any Person in which (x) the gross consideration paid, directly or indirectly,
by the Company in such acquisition is not greater than 20% of the Company’s market capitalization as calculated on the date
of the consummation of such merger and (y) such merger does not contemplate a change to the identity of a majority of the
board of directors of the Company. Notwithstanding anything herein to the contrary, any transaction or series of transactions that,
directly or indirectly, results in the Company or the Successor Entity not having Common Stock or common stock, as applicable,
registered under the Exchange Act and listed on an Eligible Market shall be deemed a Change of Control.


 






     


     


    

 


(h)
 “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 9. 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.


 


(i) “Common
Stock” means (i) the Company’s Common Stock, par value $0.001 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.


 


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


 


(k) “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.


 


(l) “Exercise
Price” means $[___] per share of Common Stock, subject to adjustment as provided herein.


 






     


     


    

 


(m)
 “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 Exchange 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 Exchange
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 Exchange 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 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.


 


(n) “Group”
means a “group” as that term is used in Section 13(d) of the Exchange Act and as defined in Rule 13d-5 thereunder.


 


(o) “Options”
means any rights, warrants or options to subscribe for or purchase shares of Common Stock or Convertible Securities.


 


(p)
 “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.


 






     


     


    

 


(q) “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.


 


(r) “Principal
Market” means the Nasdaq Capital Market.


 


(s) “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.


 


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


 


(u) “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.


 


(v) “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.


 


(w) “Transaction
Documents” means any agreement entered into by and between the Company and the Holder, as applicable.


 


(x) “Warrant
Shares” means [                  (                )]
shares of fully paid non-assessable shares of Common Stock (as defined above).


 






     


     


    

 


(y)
 “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 9 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]


 






     


     


    

 


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.


 


	 	IDERA PHARMACEUTICALS, INC.




 


 


	 	By:
	 	Name:
	 	Title:




 






     


     


    

 


EXHIBIT A


 


EXERCISE NOTICE


TO BE EXECUTED
BY THE REGISTERED HOLDER TO EXERCISE THIS 


WARRANT TO PURCHASE
COMMON STOCK 


 


IDERA PHARMACEUTICALS,
INC.


 


 


The undersigned
holder hereby exercises the right to purchase                 
shares of Common Stock (“Warrant Shares”) of Idera Pharmaceuticals, 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.


 


Form of Exercise Price. The
Holder intends that payment of the Exercise Price shall be made as:


 


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


 


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.


 


Delivery of Warrant Shares.
The Company shall deliver to the holder                 
shares of Common Stock 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 [Transfer Agent] to issue the above indicated number of Warrant Shares on
or prior to the applicable Share Delivery Date.


 


	 	IDERA PHARMACEUTICALS, INC.




 


 


	 	By:	 
	 	Name:	 
	 	Title: