UNITED
STATES

SECURITIES
AND EXCHANGE COMMISSION

Washington,
D.C. 20549



FORM
10-K/A



(Mark
One)



|[X] | ANNUAL
    REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934
|--- | ----------------------------------------------------------------------------------------



For
the fiscal year ended December 31, 2019



OR



|[  ] | TRANSITION
    REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934
|---- | --------------------------------------------------------------------------------------------



FOR
THE TRANSITION PERIOD FROM ______ TO



Commission
File Number 001-38738



ETON
PHARMACEUTICALS, INC.

(Exact
name of registrant as specified in its charter)



|Delaware                                                                                                 |  | 37-1858472                                                                                   
|-------------------------------------------------------------------------------------------------------- |  | ---------------------------------------------------------------------------------------------
|(State
or other jurisdiction
of incorporation or organization)                                           |  | (I.R.S.
                                         Employer
        Identification
        No.)
|                                                                                                         |  |                                                                                              
|21925
                                         W. Field Parkway, Suite 235
        Deer
        Park, IL |  | 60010-7208                                                                                   
|(Address
    of principal executive offices)                                                             |  | (Zip
    Code)                                                                               



Registrant’s
telephone number, including area code: (847) 787-7361



Securities
registered pursuant to Section 12(b) of the Act:



|Title
    of each class            |  | Trading
    Symbol |  | Name
    of each exchange on which registered
|---------------------------------- |  | ------------------ |  | ---------------------------------------------
|Common
    Stock, $0.001 par value |  | ETON               |  | The
    Nasdaq Global Market                 



Securities
registered pursuant to Section 12(g) of the Act: None



Indicate
by check mark if the registrant is a well-known seasoned issuer, as defined in Rule 405 of the Securities Act. YES [  ]
NO [X]



Indicate
by check mark if the registrant is not required to file reports pursuant to Section 13 or 15(d) of the Act. YES [  ]
NO [X]



Indicate
by check mark whether the registrant: (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities
Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such
reports), and (2) has been subject to such filing requirements for the past 90 days. YES [X] NO [  ]



Indicate
by check mark whether the registrant has submitted electronically every Interactive Data File required to be submitted pursuant
to Rule 405 of Regulation S-T (§232.405 of this chapter) during the preceding 12 months (or for such shorter period that
the registrant was required to submit such files). YES [X] NO [  ]



Indicate
by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting
company, or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,”
“smaller reporting company,” and “emerging growth company” in Rule 12b-2 of the Exchange Act.



|Large
    accelerated filer | [  ] |  | Accelerated
    filer         | [X]
|--------------------------- | ---- |  | ----------------------------- | ---
|Non-accelerated
    filer   | [  ] |  | Smaller
    reporting company | [X]
|                            |      |  | Emerging
    growth company   | [X]



If
an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for
complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. [X]



Indicate
by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act). YES [  ] NO
[X]



The
aggregate market value of all common stock (based upon the closing price on the Nasdaq Global Market) of the registrant held by
non-affiliates as of June 30, 2019 was approximately $96.6 million.



As
of February 28, 2020, the registrant had 17,882,486 shares of common stock, $0.001 par value per share, outstanding.



DOCUMENTS
INCORPORATED BY REFERENCE



Portions
of the registrant’s definitive proxy statement for its 2020 Annual Meeting of Stockholders, which the registrant intends
to file pursuant to Regulation 14A with the Securities and Exchange Commission not later than 120 days after the registrant’s
fiscal year ended December 31, 2019, are incorporated by reference into Part III of this Annual Report on Form 10-K.


















Explanatory
Notes.



1.
Pursuant to the request of the Staff of the Division of Corporation Finance, the registrant hereby amends the third paragraph
on page 6 of its Annual Report on Form 10-K for the year ended December 31, 2019 (paragraph 3 in Item 1. Business –
Licensing Arrangements) to read in its entirety as follows:



ET-105.On June 12, 2019, we entered into an Exclusive Licensing and Supply Agreement (the “ET-105 License Agreement”)
with Aucta Pharmaceuticals, Inc. (“Aucta”) for marketing rights in the United States to ET-105. Pursuant to the terms
of the ET-105 License Agreement, we will be responsible for marketing activities and Aucta will be responsible for development,
manufacturing, and regulatory activities related to obtaining regulatory approval. We paid Aucta a licensing payment of $2,000,000
in August 2019 upon receiving an acceptance for review letter from the FDA and will pay $2,000,000 upon FDA approval and the commencement
of commercial sales of the product and another $1,000,000 upon issuance of an Orange-book listed patent. Aucta will receive a
royalty of fifteen percent of net sales and will be entitled to receive additional milestone payments of up to $18,000,000 in
total based on commercial success of the product, including: $1,000,000 when net sales exceed $10 million in a calendar year;
$2,000,000 when net sales exceed $20 million in a calendar year; $5,000,000 when net sales exceed $50 million in a calendar year;
and $10,000,000 when net sales exceed $100 million in a calendar year.



2.
Pursuant to the request of the Staff of the Division of Corporation Finance, the registrant hereby amends the second
paragraph on page 7 of its Annual Report on Form 10-K for the year ended December 31, 2019 (paragraph 5 in Item 1. Business
– Licensing Arrangements) to read in its entirety as follows:



On
February 18, 2019, we entered into an Asset Purchase Agreement with Bausch. Pursuant to the Asset Purchase Agreement, we sold
all of our right, title and interest in EM-100 in the United States, including any such product that incorporates or utilizes
our intellectual property rights with respect to EM-100. Pursuant to the Asset Purchase Agreement, Bausch paid us an upfront payment
of $500,000 and Bausch is required to pay us a milestone payment of $1,500,000 upon the first sale of the product. Bausch is required
to pay us a royalty of twelve percent of net sales for a period of 10 years from the date of the first commercial sale of the
first single agent EM-100 product in the United States. In the event that any product with the same sole active pharmaceutical
ingredient (“API”) as EM-100 is launched in the United States by any person other than Bausch (or its affiliates)
during the term of Bausch’s royalty commitment, then the royalty rate will be reduced to a lower specified percentage. In
the event that EM-100’s market share in the territory falls below a certain percentage of the target market during the term
of Bausch’s royalty commitment, then the royalty rate will be further reduced to a lower specified percentage.



2







Exhibit
Index





|Exhibit
                              No. |  | Description                                                                                                                                            
|----------------------------------------- |  | -------------------------------------------------------------------------------------------------------------------------------------------------------
|                                          |  |                                                                                                                                                        
|31.1                                      |  | Certification
    of President and Chief Executive Officer (Principal Executive Officer) Pursuant to Section 302 of the Sarbanes-Oxley Act of
    2002.
|                                          |  |                                                                                                                                                        
|31.2                                      |  | Certification
    of Chief Financial Officer (Principal Financial Officer) Pursuant to Section 302 of the Sarbanes-Oxley Act of 2002.                  





3







SIGNATURES



Pursuant
to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this amendment to be signed on its
behalf by the undersigned thereunto duly authorized.



|                 | ETON
    PHARMACEUTICALS, INC.
|---------------- | ------------------------------
|                 |                               
|May
    21, 2020 | By:                           
|                 |                               
|                 |                               
|                 |                               
|                 |                               
|                 | By:                           
|                 |                               
|                 |                               
|                 |                               



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