Exhibit 4.1


 


SERIES [A/B/C] COMMON STOCK PURCHASE WARRANT


 


moleculin
biOtech, inc.


 


	Warrant Shares: _______	Initial Exercise Date: _______, 2017


 


THIS SERIES [A/B/C] COMMON
STOCK PURCHASE WARRANT (the “Warrant”) certifies that, for value received, _____________ or its assigns (the
“Holder”) is entitled, upon the terms and subject to the limitations on exercise and the conditions hereinafter
set forth, at any time on or after the date hereof (the “Initial Exercise Date”) and on or prior to the close
of business on the _____1 anniversary of the Initial Exercise Date (the “Termination Date”) but not
thereafter, to subscribe for and purchase from Moleculin Biotech, Inc., a Delaware corporation (the “Company”),
up to ______ shares (as subject to adjustment hereunder, the “Warrant Shares”) of Common Stock [;provided,
however, the exercisability of this Series C Warrant shall vest ratably from time to time in proportion to the Holder’s
(or its permitted assigns) exercise of the Series B Common Stock Purchase Warrant as compared with all Series B Common Stock Purchase
Warrants issued to the Holder on the Initial Exercise Date (“Vesting Schedule”). By way of an example, if the
Holder exercises all of its Series B Common Stock Purchase Warrants, all Warrant Shares hereunder may be exercised by the Holder,
if the Holder exercises half of the Series B Common Stock Purchase Warrant, only half of the Warrant Shares hereunder may be exercised
by the Holder until such time that the Holder exercises additional Series B Common Stock Purchase Warrants.]2 The purchase
price of one share of Common Stock under this Warrant shall be equal to the Exercise Price, as defined in Section 2(b).


 


Section 1.          Definitions.
In addition to the terms defined elsewhere in this Warrant, the following terms have the meanings indicated in this Section 1:


 


“Affiliate”
means any Person that, directly or indirectly through one or more intermediaries, controls or is controlled by or is under common
control with a Person, as such terms are used in and construed under Rule 405 under the Securities Act.


 


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


 


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


 


“Common
Stock Equivalents” means any securities of the Company or 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.


 





 






1         Series A Warrant: 5 year;
Series B Warrant: 90 day; Series C Warrant: 5 year


2         Series C Warrant only


 




    	 	1	 



     


    

 


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


 


“Person”
means an individual or corporation, partnership, trust, incorporated or unincorporated association, joint venture, limited liability
company, joint stock company, government (or an agency or subdivision thereof) or other entity of any kind.


 


“Securities
Act” means the Securities Act of 1933, as amended, and the rules and regulations promulgated thereunder.


 


“Trading
Day” means a day on which the Common Stock is traded on a Trading Market.


 


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


 


“Transfer
Agent” means VStock Transfer, LLC, the current transfer agent of the Company, with a mailing address of 18 Lafayette
Place, Woodmere, New York 11598 and a facsimile number of (646) 536-3179, and any successor transfer agent of the Company.


 


Section 2.          Exercise.


 


a)        [Subject
to the Vesting Schedule,3] Exercise of the purchase rights represented by this Warrant may be made, in whole or in part,
at any time or times on or after the Initial Exercise Date and on or before the Termination Date by delivery to the Company (or
such other office or agency of the Company as it may designate by notice in writing to the registered Holder at the address of
the Holder appearing on the books of the Company) of a duly executed facsimile copy (or e-mail attachment) of the Notice of Exercise
in the form annexed hereto. Within the earlier of (i) three (3) Trading Days and (ii) the number of Trading Days comprising the
Standard Settlement Period (as defined in Section 2(d)(i) herein) following the date of exercise as aforesaid, the Holder shall
deliver the aggregate Exercise Price for the shares specified in the applicable Notice of Exercise by wire transfer or cashier’s
check drawn on a United States bank unless the cashless exercise procedure specified in Section 2(c) below is specified in the
applicable Notice of Exercise. No ink-original Notice of Exercise shall be required, nor shall any medallion guarantee (or
other type of guarantee or notarization) of any Notice of Exercise form be required. Notwithstanding anything herein to the contrary,
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 the final Notice of Exercise is delivered to the Company.
Partial exercises of this Warrant resulting in purchases of a portion of the total number of Warrant Shares available hereunder
shall have the effect of lowering the outstanding number of Warrant Shares purchasable hereunder in an amount equal to the applicable
number of Warrant Shares purchased. The Holder and the Company shall maintain records showing the number of Warrant Shares purchased
and the date of such purchases. The Company shall deliver any objection to any Notice of Exercise within one (1) Business Day of
receipt of such notice. The Holder and any assignee, by acceptance of this Warrant, acknowledge and agree that, by reason of
the provisions of this paragraph, following the purchase of a portion of the Warrant Shares hereunder, the number of Warrant Shares
available for purchase hereunder at any given time may be less than the amount stated on the face hereof.


 


 






3  Series C Warrant only.


  




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b)        Exercise
Price. The exercise price per share of the Common Stock under this Warrant shall be $_____,4 subject to adjustment
hereunder (the “Exercise Price”).


 


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


 


(A) = as
applicable: (i) the VWAP on the Trading Day immediately preceding the date of the applicable Notice of Exercise if such
Exercise Notice is (1) both executed and delivered pursuant to Section 2(a) hereof on a day that is not a Trading Day or (2)
both executed and delivered pursuant to Section 2(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) the Bid Price of the Common Stock on the principal Trading Market as reported by Bloomberg L.P. as of the time of
the Holder’s execution of the applicable Exercise Notice if such Exercise Notice of Exercise is executed during
“regular trading hours” on a Trading Day and is delivered within two (2) hours thereafter pursuant to Section
2(a) hereof or (iii) the VWAP on the date of the applicable Exercise Notice if the date of such Notice of Exercise is a
Trading Day and such Notice of Exercise is both executed and delivered pursuant to Section 1(a) hereof after the close of
“regular trading hours” on such Trading Day;


 


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


 


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


 


 






4 Series A Warrant: $1.50; Series
B Warrant: $1.35; Series C Warrant: $1.50


 




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


 


“Bid
Price” means, for any date, the price determined by the first of the following clauses that applies: (a) if the Common
Stock is then listed or quoted on a Trading Market, the bid price of the Common Stock for the time in question (or the nearest
preceding date) on the Trading Market on which the Common Stock is then listed or quoted as reported by Bloomberg L.P. (based on
a Trading Day from 9:30 a.m. (New York City time) to 4:02 p.m. (New York City time)), (b)  if OTCQB or OTCQX is not a Trading
Market, the volume weighted average price of the Common Stock for such date (or the nearest preceding date) on OTCQB or OTCQX as
applicable, (c) if the Common Stock is not then listed or quoted for trading on OTCQB or OTCQX and if prices for the Common Stock
are then reported in the “Pink Sheets” published by OTC Markets Group, Inc. (or a similar organization or agency succeeding
to its functions of reporting prices), the most recent bid price per share of the Common Stock so reported, or (d) in all
other cases, the fair market value of a share of Common Stock as determined by an independent appraiser selected in good faith
by the Purchasers of a majority in interest of the Securities then outstanding and reasonably acceptable to the Company, the fees
and expenses of which shall be paid by the Company.


 


“VWAP”
means, for any date, the price determined by the first of the following clauses that applies: (a) if the Common Stock is then listed
or quoted on a Trading Market, the daily volume weighted average price of the Common Stock for such date (or the nearest preceding
date) on the Trading Market on which the Common Stock is then listed or quoted as reported by Bloomberg L.P. (based on a Trading
Day from 9:30 a.m. (New York City time) to 4:02 p.m. (New York City time)), (b)  if OTCQB or OTCQX is not a Trading Market,
the volume weighted average price of the Common Stock for such date (or the nearest preceding date) on OTCQB or OTCQX as applicable,
(c) if the Common Stock is not then listed or quoted for trading on OTCQB or OTCQX and if prices for the Common Stock are then
reported in the “Pink Sheets” published by OTC Markets Group, Inc. (or a similar organization or agency succeeding
to its functions of reporting prices), the most recent bid price per share of the Common Stock so reported, or (d) in all
other cases, the fair market value of a share of Common Stock as determined by an independent appraiser selected in good faith
by the holders of a majority in interest of the Warrants then outstanding and reasonably acceptable to the Company, the fees and
expenses of which shall be paid by the Company.


 




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d)            Mechanics
of Exercise.


 


i.            Delivery
of Warrant Shares Upon Exercise. The Company shall cause the Warrant Shares purchased hereunder to be transmitted by the Transfer
Agent to the Holder by crediting the account of the Holder’s or its designee’s balance account with The Depository
Trust Company through its Deposit or Withdrawal at Custodian system (“DWAC”) if the Company is then a participant
in such system and either (A) there is an effective registration statement permitting the issuance of the Warrant Shares to or
resale of the Warrant Shares by Holder or (B) this Warrant is being exercised via cashless exercise, and otherwise by physical
delivery of a certificate, registered in the Company’s share register in the name of the Holder or its designee, for the
number of Warrant Shares to which the Holder is entitled pursuant to such exercise to the address specified by the Holder in the
Notice of Exercise by the date that is the earlier of (i) the earlier of (A) three (3) Trading Days after the delivery to the Company
of the Notice of Exercise and (B) one (1) Trading Day after delivery of the aggregate Exercise Price and (ii) the number of Trading
Days comprising the Standard Settlement Period after the delivery to the Company of the Notice of Exercise (such date, the “Warrant
Share Delivery Date”). Upon delivery of the Notice of Exercise, the Holder shall be deemed for all corporate purposes
to have become the holder of record of the Warrant Shares with respect to which this Warrant has been exercised, irrespective of
the date of delivery of the Warrant Shares, provided that payment of the aggregate Exercise Price (other than in the case of a
cashless exercise) is received within the earlier of (i) three Trading Days and (ii) the number of Trading Days comprising the
Standard Settlement Period following delivery of the Notice of Exercise. If the Company fails for any reason to deliver to the
Holder the Warrant Shares subject to a Notice of Exercise by the Warrant 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 Warrant Share Delivery Date
until such Warrant Shares are delivered or Holder rescinds such exercise. The Company agrees to maintain a transfer agent that
is a participant in the FAST program so long as this Warrant remains outstanding and exercisable. As used herein, “Standard
Settlement Period” means the standard settlement period, expressed in a number of Trading Days, on the Company’s
primary Trading Market with respect to the Common Stock as in effect on the date of delivery of the Notice of Exercise.


 


ii.         Delivery
of New Warrants Upon Exercise. If this Warrant shall have been exercised in part, the Company shall, at the request of a Holder
and upon surrender of this Warrant certificate, at the time of delivery of the Warrant Shares, deliver to the Holder a new Warrant
evidencing the rights of the Holder to purchase the unpurchased Warrant Shares called for by this Warrant, which new Warrant shall
in all other respects be identical with this Warrant.


 


iii.         Rescission
Rights. If the Company fails to cause the Transfer Agent to transmit to the Holder the Warrant Shares pursuant to Section 2(d)(i)
by the Warrant Share Delivery Date, then the Holder will have the right to rescind such exercise.


 




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iv.         Compensation
for Buy-In on Failure to Timely Deliver Warrant Shares Upon Exercise. In addition to any other rights available to the Holder,
if the Company fails to cause the Transfer Agent to transmit to the Holder the Warrant Shares in accordance with the provisions
of Section 2(d)(i) above pursuant to an exercise on or before the Warrant Share Delivery Date, and 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 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.


 


v.           No
Fractional Shares or Scrip. No fractional shares or scrip representing fractional shares shall be issued upon the exercise
of this Warrant. As to any fraction of a share which the Holder would otherwise be entitled to purchase upon such exercise, the
Company shall, at its election, either pay a cash adjustment in respect of such final fraction in an amount equal to such fraction
multiplied by the Exercise Price or round up to the next whole share.


 




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vi.         Charges,
Taxes and Expenses. Issuance of Warrant Shares shall be made without charge to the Holder for any issue or transfer tax or
other incidental expense in respect of the issuance of such Warrant Shares, all of which taxes and expenses shall be paid by the
Company, and such Warrant Shares shall be issued in the name of the Holder or in such name or names as may be directed by the Holder;
provided, however, that in the event that Warrant Shares are to be issued in a name other than the name of the Holder,
this Warrant when surrendered for exercise shall be accompanied by the Assignment Form attached hereto duly executed by the Holder
and the Company may require, as a condition thereto, the payment of a sum sufficient to reimburse it for any transfer tax incidental
thereto. The Company shall pay all Transfer Agent fees required for same-day processing of any Notice of Exercise and all fees
to the Depository Trust Company (or another established clearing corporation performing similar functions) required for same-day
electronic delivery of the Warrant Shares.


 


vii.         Closing
of Books. The Company will not close its stockholder books or records in any manner which prevents the timely exercise of this
Warrant, pursuant to the terms hereof.


 


e)             Holder’s
Exercise Limitations. The Company shall not effect any exercise of this Warrant, and a Holder shall not have the right to
exercise any portion of this Warrant, pursuant to Section 2 or otherwise, to the extent that after giving effect to such issuance
after exercise as set forth on the applicable Notice of Exercise, the Holder (together with the Holder’s Affiliates, and
any other Persons acting as a group together with the Holder or any of the Holder’s Affiliates (such Persons, “Attribution
Parties”)), would beneficially own in excess of the Beneficial Ownership Limitation (as defined below).  For purposes
of the foregoing sentence, the number of shares of Common Stock beneficially owned by the Holder and its Affiliates and Attribution
Parties shall include the number of shares of Common Stock issuable upon exercise of this Warrant with respect to which such determination
is being made, but shall exclude the number of shares of Common Stock which would be issuable upon (i) exercise of the remaining,
nonexercised portion of this Warrant beneficially owned by the Holder or any of its Affiliates or Attribution Parties and (ii)
exercise or conversion of the unexercised or nonconverted portion of any other securities of the Company (including, without limitation,
any other Common Stock Equivalents) subject to a limitation on conversion or exercise analogous to the limitation contained herein
beneficially owned by the Holder or any of its Affiliates or Attribution Parties.  Except as set forth in the preceding sentence,
for purposes of this Section 2(e), beneficial ownership shall be calculated in accordance with Section 13(d) of the Exchange Act
and the rules and regulations promulgated thereunder, it being acknowledged by the Holder that the Company is not representing
to the Holder that such calculation is in compliance with Section 13(d) of the Exchange Act and the Holder is solely responsible
for any schedules required to be filed in accordance therewith. To the extent that the limitation contained in this Section 2(e)
applies, the determination of whether this Warrant is exercisable (in relation to other securities owned by the Holder together
with any Affiliates and Attribution Parties) and of which portion of this Warrant is exercisable shall be in the sole discretion
of the Holder, and the submission of a Notice of Exercise shall be deemed to be the Holder’s determination of whether this
Warrant is exercisable (in relation to other securities owned by the Holder together with any Affiliates and Attribution Parties)
and of which portion of this Warrant is exercisable, in each case subject to the Beneficial Ownership Limitation, and the Company
shall have no obligation to verify or confirm the accuracy of such determination. In addition, a determination as to any group
status as contemplated above shall be determined in accordance with Section 13(d) of the Exchange Act and the rules and regulations
promulgated thereunder. For purposes of this Section 2(e), in determining the number of outstanding shares of Common Stock, a
Holder may rely on the number of outstanding shares of Common Stock as reflected in (A) the Company’s most recent periodic
or annual report filed with the Commission, as the case may be, (B) a more recent public announcement by the Company or (C) a
more recent written notice by the Company or the Transfer Agent setting forth the number of shares of Common Stock outstanding. 
Upon the written or oral request of a Holder, the Company shall within two Trading Days confirm orally and in writing to the Holder
the number of shares of Common Stock then outstanding.  In any case, the number of outstanding shares of Common Stock shall
be determined after giving effect to the conversion or exercise of securities of the Company, including this Warrant, by the Holder
or its Affiliates or Attribution Parties since the date as of which such number of outstanding shares of Common Stock was reported.
The “Beneficial Ownership Limitation” shall be 4.99% of the number of shares of the Common Stock outstanding
immediately after giving effect to the issuance of shares of Common Stock issuable upon exercise of this Warrant. The Holder,
upon notice to the Company, may increase or decrease the Beneficial Ownership Limitation provisions of this Section 2(e), provided
that the Beneficial Ownership Limitation in no event exceeds 9.99% of the number of shares of the Common Stock outstanding immediately
after giving effect to the issuance of shares of Common Stock upon exercise of this Warrant held by the Holder and the provisions
of this Section 2(e) shall continue to apply. Any increase in the Beneficial Ownership Limitation will not be effective until
the 61st day after such notice is delivered to the Company. The provisions of this paragraph shall be construed and
implemented in a manner otherwise than in strict conformity with the terms of this Section 2(e) to correct this paragraph (or
any portion hereof) which may be defective or inconsistent with the intended Beneficial Ownership Limitation herein contained
or to make changes or supplements necessary or desirable to properly give effect to such limitation. The limitations contained
in this paragraph shall apply to a successor holder of this Warrant.


 




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Section 3.          Certain
Adjustments.


 


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


 




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b)        [Reserved]


 


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


 


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


 




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e)        Fundamental
Transaction. If, at any time while this Warrant is outstanding, (i) the Company, directly or indirectly, in one or more related
transactions effects any merger or consolidation of the Company with or into another Person, (ii) the Company, directly or indirectly,
effects any sale, lease, license, assignment, transfer, conveyance or other disposition of all or substantially all of its assets
in one or a series of related transactions, (iii) any, direct or indirect, purchase offer, tender offer or exchange offer (whether
by the Company or another Person) is completed pursuant to which holders of Common Stock are permitted to sell, tender or exchange
their shares for other securities, cash or property and has been accepted by the holders of 50% or more of the outstanding Common
Stock, (iv) the Company, directly or indirectly, in one or more related transactions effects any reclassification, reorganization
or recapitalization of the Common Stock or any compulsory share exchange pursuant to which the Common Stock is effectively converted
into or exchanged for other securities, cash or property, or (v) the Company, directly or indirectly, in one or more related transactions
consummates a stock or share purchase agreement or other business combination (including, without limitation, a reorganization,
recapitalization, spin-off or scheme of arrangement) with another Person or group of Persons whereby such other Person or group
acquires more than 50% of the outstanding shares of Common Stock (not including any shares of Common Stock held by the other Person
or other Persons making or party to, or associated or affiliated with the other Persons making or party to, such stock or share
purchase agreement or other business combination) (each a “Fundamental Transaction”), then, upon any subsequent
exercise of this Warrant, the Holder shall have the right to receive, for each Warrant Share that would have been issuable upon
such exercise immediately prior to the occurrence of such Fundamental Transaction, at the option of the Holder (without regard
to any limitation in Section 2(e) on the exercise of this Warrant), the number of shares of Common Stock of the successor or acquiring
corporation or of the Company, if it is the surviving corporation, and any additional consideration (the “Alternate Consideration”)
receivable as a result of such Fundamental Transaction by a holder of the number of shares of Common Stock for which this Warrant
is exercisable immediately prior to such Fundamental Transaction (without regard to any limitation in Section 2(e) on the exercise
of this Warrant). For purposes of any such exercise, the determination of the Exercise Price shall be appropriately adjusted to
apply to such Alternate Consideration based on the amount of Alternate Consideration issuable in respect of one share of Common
Stock in such Fundamental Transaction, and the Company shall apportion the Exercise Price among the Alternate Consideration in
a reasonable manner reflecting the relative value of any different components of the Alternate Consideration. If holders of Common
Stock are given any choice as to the securities, cash or property to be received in a Fundamental Transaction, then the Holder
shall be given the same choice as to the Alternate Consideration it receives upon any exercise of this Warrant following such
Fundamental Transaction. Notwithstanding anything to the contrary, in the event of a Fundamental Transaction, the Company or any
Successor Entity (as defined below) shall, at the Holder’s option, exercisable at any time concurrently with, or within
30 days after, the consummation of the 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. “Black Scholes Value” means the value of this Warrant based on the Black and
Scholes Option Pricing Model obtained from the “OV” function on Bloomberg, L.P. (“Bloomberg”) determined
as of the day of consummation of the applicable Fundamental Transaction for pricing purposes and reflecting (A) a risk-free interest
rate corresponding to the U.S. Treasury rate for a period equal to the time between the date of the public announcement of the
applicable Fundamental Transaction and the Termination Date, (B) 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, (C) the underlying price per share used in such calculation shall be 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 such Fundamental
Transaction and (D) a remaining option time equal to the time between the date of the public announcement of the applicable Fundamental
Transaction and the Termination Date. The payment of the Black Scholes Value will be made by wire transfer of immediately available
funds within five Business Days of the Holder’s election (or, if later, on the effective date of the Fundamental Transaction).
The Company shall cause any successor entity in a Fundamental Transaction in which the Company is not the survivor (the “Successor
Entity”) to assume in writing all of the obligations of the Company under this Warrant in accordance with the provisions
of this Section 3(e) pursuant to written agreements in form and substance reasonably satisfactory to and approved by a majority
of the holders of Warrants (without unreasonable delay) prior to such Fundamental Transaction and shall, at the option of the
Holder, deliver to the Holder in exchange for this Warrant a security of the Successor Entity evidenced by a written instrument
substantially similar in form and substance to this Warrant which is exercisable for a corresponding number of shares of capital
stock of such Successor Entity (or its parent entity) equivalent to the shares of Common Stock acquirable and receivable upon
exercise of this Warrant (without regard to any limitations on the exercise of this Warrant) prior to such Fundamental Transaction,
and with an exercise price which applies the exercise price hereunder to such shares of capital stock (but taking into account
the relative value of the shares of Common Stock pursuant to such Fundamental Transaction and the value of such shares of capital
stock, such number of shares of capital stock and such exercise price being for the purpose of protecting the economic value of
this Warrant immediately prior to the consummation of such Fundamental Transaction). Upon the occurrence of any such Fundamental
Transaction, the Successor Entity shall succeed to, and be substituted for (so that from and after the date of such Fundamental
Transaction, the provisions of this Warrant referring to the “Company” shall refer instead to the Successor Entity),
and may exercise every right and power of the Company and shall assume all of the obligations of the Company under this Warrant
with the same effect as if such Successor Entity had been named as the Company herein.


 




    	 	10	 



     


    

 


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


 


g)        Notice
to Holder.


 


i.          Adjustment
to Exercise Price. Whenever the Exercise Price is adjusted pursuant to any provision of this Section 3, the Company shall promptly
deliver to the Holder by facsimile or email a notice setting forth the Exercise Price after such adjustment and any resulting adjustment
to the number of Warrant Shares and setting forth a brief statement of the facts requiring such adjustment.


 


ii.         Notice
to Allow Exercise by Holder. If (A) the Company shall declare a dividend (or any other distribution in whatever form) on the
Common Stock, (B) the Company shall declare a special nonrecurring cash dividend on or a redemption of the Common Stock, (C) the
Company shall authorize the granting to all holders of the Common Stock rights or warrants to subscribe for or purchase any shares
of capital stock of any class or of any rights, (D) the approval of any stockholders of the Company shall be required in connection
with any reclassification of the Common Stock, any consolidation or merger to which the Company is a party, any sale or transfer
of all or substantially all of the assets of the Company, or any compulsory share exchange whereby the Common Stock is converted
into other securities, cash or property, or (E) the Company shall authorize the voluntary or involuntary dissolution, liquidation
or winding up of the affairs of the Company, then, in each case, the Company shall cause to be delivered by facsimile or email
to the Holder at its last facsimile number or email address as it shall appear upon the Warrant Register of the Company, at least
20 calendar days prior to the applicable record or effective date hereinafter specified, a notice stating (x) the date on which
a record is to be taken for the purpose of such dividend, distribution, redemption, rights or warrants, or if a record is not to
be taken, the date as of which the holders of the Common Stock of record to be entitled to such dividend, distributions, redemption,
rights or warrants are to be determined or (y) the date on which such reclassification, consolidation, merger, sale, transfer or
share exchange is expected to become effective or close, and the date as of which it is expected that holders of the Common Stock
of record shall be entitled to exchange their shares of the Common Stock for securities, cash or other property deliverable upon
such reclassification, consolidation, merger, sale, transfer or share exchange; provided that the failure to deliver such notice
or any defect therein or in the delivery thereof shall not affect the validity of the corporate action required to be specified
in such notice. To the extent that any notice provided in this Warrant constitutes, or contains, material, non-public information
regarding the Company or any of the Subsidiaries, the Company shall simultaneously file such notice with the Commission pursuant
to a Current Report on Form 8-K. The Holder shall remain entitled to exercise this Warrant during the period commencing on the
date of such notice to the effective date of the event triggering such notice except as may otherwise be expressly set forth herein.


 




    	 	11	 



     


    

 


iii.         Voluntary
Adjustments by the Company. The Company may, at any time during the term of this Warrant, reduce the then current Exercise
Price to any amount and extend the term of this Warrant for any period of time deemed appropriate by the Board of Directors of
the Company, provided that the Exercise Price shall not be reduced to less than the par value of the Common Stock.


 


Section 4.          Transfer
of Warrant.


 


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


 


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


 




    	 	12	 



     


    

 


c)        Warrant
Register. The Company shall register this Warrant, upon records to be maintained by the Company for that purpose (the “Warrant
Register”), in the name of the record Holder hereof from time to time. The Company may deem and treat the registered
Holder of this Warrant as the absolute owner hereof for the purpose of any exercise hereof or any distribution to the Holder,
and for all other purposes, absent actual notice to the contrary.


 


Section 5.          Miscellaneous.


 


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


 


b)        Loss, Theft,
Destruction or Mutilation of Warrant. The Company covenants that upon receipt by the Company of evidence reasonably satisfactory
to it of the loss, theft, destruction or mutilation of this Warrant or any stock certificate relating to the Warrant Shares, and
in case of loss, theft or destruction, of indemnity or security reasonably satisfactory to it (which, in the case of the Warrant,
shall not include the posting of any bond), and upon surrender and cancellation of such Warrant or stock certificate, if mutilated,
the Company will make and deliver a new Warrant or stock certificate of like tenor and dated as of such cancellation, in lieu
of such Warrant or stock certificate.


 


c)        Saturdays,
Sundays, Holidays, etc. If the last or appointed day for the taking of any action or the expiration of any right required or
granted herein shall not be a Business Day, then, such action may be taken or such right may be exercised on the next succeeding
Business Day.


 


d)        Authorized
Shares.


 


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


 




    	 	13	 



     


    

 


Except and to the
extent as waived or consented to by the Holder, the Company shall not by any action, including, without limitation, amending its
certificate of incorporation or through any reorganization, transfer of assets, consolidation, merger, dissolution, issue or sale
of securities or any other voluntary action, avoid or seek to avoid the observance or performance of any of the terms of this Warrant,
but will at all times in good faith assist in the carrying out of all such terms and in the taking of all such actions as may be
necessary or appropriate to protect the rights of Holder as set forth in this Warrant against impairment. Without limiting the
generality of the foregoing, the Company will (i) not increase the par value of any Warrant Shares above the amount payable therefor
upon such exercise immediately prior to such increase in par value, (ii) take all such action as may be necessary or appropriate
in order that the Company may validly and legally issue fully paid and nonassessable Warrant Shares upon the exercise of this Warrant
and (iii) use commercially reasonable efforts to obtain all such authorizations, exemptions or consents from any public regulatory
body having jurisdiction thereof, as may be, necessary to enable the Company to perform its obligations under this Warrant.


 


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


 


e)        Jurisdiction.
This Warrant shall be governed by and construed and enforced in accordance with the laws of the State of New York, without giving
effect to conflict of laws principles thereof. The Company hereby agrees that any action, proceeding or claim against it arising
out of, or relating in any way to this Warrant shall be brought and enforced in the New York Supreme Court, County of New York,
or in the United States District Court for the Southern District of New York located in the Borough of Manhattan in the City of
New York, and irrevocably submits to such jurisdiction, which jurisdiction shall be exclusive. The Company hereby waives any objection
to such exclusive jurisdiction and that such courts represent an inconvenient forum.


 


f)         Restrictions.
The Holder acknowledges that the Warrant Shares acquired upon the exercise of this Warrant, if not registered, and the Holder does
not utilize cashless exercise, will have restrictions upon resale imposed by state and federal securities laws.


 




    	 	14	 



     


    

 


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


 


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


 


If to the Company:


 


Moleculin Biotech, Inc.


2575 West Bellfort, Suite
333


Houston, Texas 77054


Telephone: (713) 300-5160


Attention: Jonathan P. Foster,
Chief Financial Officer


Email: jfoster@moleculin.com


 


If to a Holder,
to its address, facsimile number or e-mail address set forth herein or on the books and records of the Company.


 


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


 




    	 	15	 



     


    

 


i)         Limitation
of Liability. No provision hereof, in the absence of any affirmative action by the Holder to exercise this Warrant to purchase
Warrant Shares, and no enumeration herein of the rights or privileges of the Holder, shall give rise to any liability of the Holder
for the purchase price of any Common Stock or as a stockholder of the Company, whether such liability is asserted by the Company
or by creditors of the Company.


 


j)         Remedies.
The Holder, in addition to being entitled to exercise all rights granted by law, including recovery of damages, will be entitled
to specific performance of its rights under this Warrant. The Company agrees that monetary damages would not be adequate compensation
for any loss incurred by reason of a breach by it of the provisions of this Warrant and hereby agrees to waive and not to assert
the defense in any action for specific performance that a remedy at law would be adequate.


 


k)        Successors
and Assigns. Subject to applicable securities laws, this Warrant and the rights and obligations evidenced hereby shall inure
to the benefit of and be binding upon the successors and permitted assigns of the Company and the successors and permitted assigns
of Holder. The provisions of this Warrant are intended to be for the benefit of any Holder from time to time of this Warrant and
shall be enforceable by the Holder or holder of Warrant Shares.


 


l)         Amendment.
This Warrant may be modified or amended or the provisions hereof waived with the written consent of the Company and the Holder.


 


m)       Severability.
Wherever possible, each provision of this Warrant shall be interpreted in such manner as to be effective and valid under applicable
law, but if any provision of this Warrant shall be prohibited by or invalid under applicable law, such provision shall be ineffective
to the extent of such prohibition or invalidity, without invalidating the remainder of such provisions or the remaining provisions
of this Warrant.


 


n)        Headings.
The headings used in this Warrant are for the convenience of reference only and shall not, for any purpose, be deemed a part of
this Warrant.


 


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


 


(Signature Page Follows)


 






    	 	16	 



     


    

 




 


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


 





	 	moleculin biotech, inc.
	 	 	 
	 	By:	 
	 	 	Name:
	 	 	Title:


 




    	 	17	 



     


    

 


NOTICE OF EXERCISE


 


To:            moleculin
biotech, inc.


 


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


 


(2)       Payment
shall take the form of (check applicable box):


 


 ̈
in lawful money of the United States; or


 


 ̈
if permitted the cancellation of such number of Warrant Shares as is necessary, in accordance with the formula set forth in subsection
2(c), to exercise this Warrant with respect to the maximum number of Warrant Shares purchasable pursuant to the cashless exercise
procedure set forth in subsection 2(c).


 


(3)         Please
issue said Warrant Shares in the name of the undersigned or in such other name as is specified below:


 


	 	 


  


The Warrant Shares shall be delivered to the
following DWAC Account Number:


 


	 	 
	 	 
	 	 


 


[SIGNATURE
OF HOLDER]


 


	Name of Investing Entity:	 


 


	Signature of Authorized Signatory of Investing Entity:	 


 


	Name of Authorized Signatory:	 


 


	Title of Authorized Signatory:	 


 


	Date:	 


 




     


     


    

 


EXHIBIT B


 


ASSIGNMENT
FORM


(To assign the foregoing
Warrant, execute this form and supply required information. Do not use this form to purchase shares.)


 


FOR VALUE RECEIVED, the
foregoing Warrant and all rights evidenced thereby are hereby assigned to


 


	Name:	 
	 	(Please Print)
	Address:	 
	 	(Please Print)
	Phone Number:	 
	Email Address: 	 
	Dated: _______________ __, ______	 
	Holder’s Signature:_______________________	 
	Holder’s Address:________________________