PHIO Phio Pharmaceuticals Corporation

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

Schedule 13D

(Rule 13d-101)

INFORMATION TO BE INCLUDED IN STATEMENTS FILED PURSUANT

TO RULE 13d-1(a) AND AMENDMENTS THERETO FILED PURSUANT TO

RULE 13d-2(a)

Under the Securities Exchange Act of 1934

PHIO PHARMACEUTICALS CORP.

(Name of Issuer)

Common stock, par value $0.0001 per share

(Title of Class of Securities)

71880W204

(CUSIP Number)

Kate Inman, Esq.

General Counsel and Secretary

OPKO Health, Inc.

4400 Biscayne Blvd.

Miami, Florida 33137

(305) 575-4100

Phillip Frost, M.D.

Frost Gamma Investments Trust

4400 Biscayne Blvd, Suite 1500

Miami, Florida 33137

(305) 575-6015

(Name, Address and Telephone Number of Person Authorized to Receive Notices and Communications)

May 9, 2019

(Date of Event which Requires Filing of this Statement)

If the filing person has previously filed a statement on Schedule 13G to report the acquisition that is the subject of this Schedule 13D, and is filing this schedule because of Rule 13d-1(e), 13d-1(f) or 13d-1(g), check the following box.  ☐

Note : Schedules filed in paper format shall include a signed original and five copies of the schedule, including all exhibits. See Rule 13d-7 for other parties to whom copies are to be sent.

The information required on the remainder of this cover page shall not be deemed to be “filed” for the purpose of Section 18 of the Securities Exchange Act of 1934 (“ Act ”) or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).

(Continued on following pages)

Page 1 of 9 Pages

EXPLANATORY NOTE

This Schedule 13D (the “ Statement ”) is filed (i) to amend and restate the Schedule 13D filed by OPKO Health, Inc. (“ OPKO ”) with the Securities and Exchange Commission (the “ SEC ”) on March 22, 2013 (the “ Original 13D ”), as amended on January 10, 2017, and the Schedule 13G filed by OPKO with the SEC on January 12, 2017 and (ii) by Phillip Frost, M.D. and Frost Gamma Investments Trust (“ FGIT ”).

On September 7, 2018, the SEC filed a civil complaint in the Southern District of New York (the “ Complaint ”), against a number of individuals and entities, including OPKO and its CEO and Chairman, Dr. Frost.

In December 2018, OPKO, Dr. Frost and FGIT entered into settlements with the SEC, which, upon approval by the court in January 2019, resolved the claims against OPKO, Dr. Frost and FGIT. Pursuant to the settlement between OPKO and the SEC, and without admitting or denying any of the allegations of the Complaint, OPKO agreed to be enjoined from future violations of Section 13(d) of the Securities Exchange Act of 1934 (the “ Exchange Act ”), a claim that requires no showing of scienter, and to pay a civil monetary penalty, which has been paid. OPKO also agreed, within certain stipulated time periods, to: (i) establish a Management Investment Committee (“ MIC ”) that will make recommendations to an Independent Investment Committee (“ IIC ”) of OPKO’s board of directors in connection with existing and future strategic minority investments; and (ii) retain an Independent Compliance Consultant (“ ICC ”) on a time-limited basis to, among other things, advise OPKO on whether filings pursuant to Section 13(d) of the Exchange Act for previous strategic minority investments made at the suggestion of or in tandem with Dr. Frost and his related persons or entities should be made or amended to reflect group membership with Dr. Frost.

Under the terms of the settlement between the SEC, Dr. Frost and FGIT, and without admitting or denying any of the allegations in the Complaint, Dr. Frost agreed to injunctions from violations of Sections 5(a) and (c) and 17(a)(2) of the Securities Act of 1933, claims which may be satisfied by strict liability and negligence, respectively, and Section 13(d) of the Exchange Act, also a strict liability claim; to pay a civil monetary penalty, disgorgement and pre-judgment interest, which have been paid; and to be prohibited, with certain exceptions, from trading in penny stocks.

The ICC has concluded his work, determined that certain prior investments in the Issuer by OPKO and Dr. Frost should have been grouped under Section 13(d) of the Exchange Act, and recommended the filing of this form.

OPKO has now established the MIC and IIC, and following the establishment of these committees, any group between OPKO, Dr. Frost, and his affiliated entities with respect to investments in the Issuer has ceased to exist.

This statement on Schedule 13D relates to the common stock, par value $0.0001 per share (the “ Common Stock ”), of Phio Pharmaceuticals Corp., a Delaware corporation (the “ Issuer ”). The principal executive offices of the Issuer are located at: 257 Simarano Drive, Suite 101 Marlborough, Massachusetts 01752.

Set forth in Schedule 1 to this Schedule 13D are the name, business address and present principal occupation or employment and citizenship of each executive officer and director of OPKO and FGIT.

(a), (f) This statement is being filed by:

(i) OPKO, a corporation incorporated under the laws of the State of Delaware;

(ii) Phillip Frost, M.D.; and

(iii) FGIT, a trust organized under the laws of the State of Florida.

The Reporting Persons have entered into a joint filing agreement, dated as of May 9, 2019, a copy of which is attached hereto as Exhibit 1.

(b) The address of the principal business and principal office of OPKO is 4400 Biscayne Blvd., Miami, Florida 33137. The address of the principal business and principal office of Dr. Frost and FGIT is 4400 Biscayne Blvd., Suite 1500, Miami, Florida 33137.

(c) OPKO is a diversified healthcare company that seeks to establish industry-leading positions in large and rapidly growing medical markets. Dr. Frost’s principal occupation is serving as Chairman and Chief Executive Officer of OPKO. The principal business of FGIT is to invest in securities. Dr. Frost is the sole trustee of FGIT. Frost Gamma Limited Partnership is the sole and exclusive beneficiary of FGIT.

(d), (e) The information set forth under the heading “Explanatory Note” above is incorporated herein by reference in its entirety to this Item 2(d) and Item 2(e). Except as disclosed above under the heading “Explanatory Note,” during the last five years, none of the Reporting Persons or any of the persons listed on Schedule I hereto (i) has been convicted in a criminal proceeding (excluding traffic violations or similar misdemeanors) or (ii) was a party to a civil proceeding of a judicial or administrative body of competent jurisdiction and as a result of such proceeding was or is subject to a judgment, decree or final order enjoining future violations of, or prohibiting or mandating activities subject to, federal or state securities laws or finding any violations with respect to such laws.

The information set forth or incorporated under the heading “Explanatory Note,” in Items 4 and 5 and the first two paragraphs of Item 4 of the Original 13D, is incorporated by reference in its entirety into this Item 3.

The source of funds used by OPKO for each of its acquisitions of securities of the Issuer and its predecessors was working capital or the exchange, exercise or conversion of securities of the Issuer or a predecessor of the Issuer previously acquired by OPKO.

The information set forth or incorporated under the heading “Explanatory Note” and in Items 2, 3 and 5 is incorporated by reference in its entirety into this Item 4.

Each of the Reporting Persons may, at any time or from time to time, formulate plans or proposals regarding the Issuer or its securities to the extent deemed advisable by the Reporting Persons in light of each of their general investment policies, market conditions, subsequent developments affecting the Issuer, the general business and future prospects of the Issuer, or other factors. The Reporting Persons intend to review their investments in the Issuer on a continuing basis. Depending on various factors, including, without limitation, the Issuer’s financial position and strategic direction, actions taken by the board of directors, price levels of shares of the Common Stock, other investment opportunities available to the Reporting Persons, concentration of positions in the portfolios managed by the Reporting Persons, market conditions and general economic and industry conditions, the Reporting Persons may in the future take such actions with respect to their investments in the Issuer as they deem appropriate, including, without limitation, purchasing additional shares of the Common Stock or other financial instruments related to the Issuer or selling some or all of their beneficial or economic holdings, engaging in hedging or similar transactions with respect to the securities relating to the Issuer and/or otherwise changing their intention with respect to any and all matters referred to in Item 4 of Schedule 13D.

Except as disclosed herein, none of the Reporting Persons has any plans or proposals which relate to or which would result in any of the actions specified in this paragraph of Item 4 of Schedule 13D.

(a), (b) The information contained in rows 7, 8, 9, 10, 11 and 13 on each of the cover pages of this Schedule 13D and the information set forth or incorporated in Items 2, 3, 4 and 6 is incorporated by reference in its entirety into this Item 5.

The following persons named in Item 2, other than the Reporting Persons, beneficially own securities of the Issuer:

OPKO’s reported ownership does not include securities beneficially owned by Mr. Paganelli, FGIT or Dr. Frost. OPKO disclaims beneficial ownership of the securities of the Issuer owned by FGIT and Dr. Frost.

Dr. Frost and FGIT’s reported ownership does not include securities owned by OPKO. In addition to serving as Chairman and Chief Executive Officer of OPKO, Dr. Frost and entities controlled by Dr. Frost (including FGIT) beneficially own approximately 35% of the outstanding common stock of OPKO. Dr. Frost and FGIT each disclaim beneficial ownership of the securities of the Issuer owned by OPKO.

(c) There have been no transactions in shares of the Common Stock effected by any Reporting Person or any of the other persons named in Item 2 in the last 60 days.

(d) No other person is known to the Reporting Persons to have the right to receive or the power to direct the receipt of dividends from, or the proceeds from the sale of, the shares of the Common Stock covered by this Schedule 13D.

(e) None of the Reporting Persons beneficially own more than 5% of the outstanding Common Stock.

The information set forth or incorporated under the heading “Explanatory Note” and in Items 2, 3, 4 and 5 is incorporated by reference in its entirety into this Item 6.

OPKO beneficially owns common stock purchase warrants exercisable for 22,222 share of Common Stock with an exercise price of $9.00 and an expiration date of December 21, 2021 (the “ Warrants ”) and 44,635 shares of Common Stock.

Except for the matters described herein, the Reporting Persons do not have any contract, arrangement, understanding or relationship (legal or otherwise) with any person with respect to the securities of the Issuer.

Reference to and description of the Warrants set forth above in this Item 6 do not purport to be complete and are qualified in their entirety by reference to the full text of the form of common stock purchase warrant, which has been filed as Exhibit 2 and is incorporated herein by this reference.

SIGNATURES

After reasonable inquiry and to the best of each of the undersigned’s knowledge and belief, each of the undersigned certify that the information set forth in this statement is true, complete and correct.

Date: May 9, 2019