UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 13D

Under the Securities Exchange Act of 1934

(Amendment No. 1)*

CASI Pharmaceuticals, Inc.

(Name of Issuer)

Common Stock, par value $0.01 per share

(Title of Class of Securities)

29382F 202

(CUSIP Number)

Kurt Gustafson

Executive Vice President and Chief Financial Officer

Spectrum Pharmaceuticals, Inc.

11500 South Eastern Avenue, Suite 240

Henderson, Nevada 89052

(702) 835-6300

with a copy to:

Teri O’Brien

Paul Hastings LLP

4747 Executive Drive, 12th Floor

San Diego, CA 92121

(858) 458-3031

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

April 17, 2018

(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 §§240.13d-1(e), 240.13d-1(f) or 240.13d-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 section 240.13d-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).

Spectrum Pharmaceuticals, Inc., a Delaware corporation (“Spectrum”), hereby files this Amendment No. 1 to supplement the statement on Schedule 13D initially filed with the SEC on September 26, 2014 (the original filing, together with this Amendment No. 1, this “Statement”) on behalf of the Reporting Persons (as defined in Item 2 below) pursuant to the Joint Filer Agreement (the “Joint Filer Agreement”) attached to this Statement as Exhibit 99.1.

Item 1. Security and Issuer.

This Statement relates to the shares of common stock, par value $0.01 per share, of CASI Pharmaceuticals, Inc., a Delaware corporation (the “Issuer”). The principal executive offices of the Issuer are located at 9620 Medical Center Drive, Suite 300, Rockville, Maryland 20850.

Item 2. Identity and Background.

This Statement is filed on behalf of Spectrum and Spectrum Pharmaceuticals Cayman, L.P., an Exempted Limited Partnership organized under the laws of the Cayman Islands (“Spectrum Cayman”). Spectrum and Spectrum Cayman are each referred to herein as a “Reporting Person” and are collectively referred to herein as the “Reporting Persons.”

Spectrum is a Delaware corporation. The principal business of Spectrum is the acquisition, development and commercialization of a broad and diverse pipeline of drug products, with a primary focus in oncology and hematology. Currently Spectrum and its affiliates market six oncology/hematology drugs— FUSILEV^® (levoleucovorin) for Injection in the U.S.; FOLOTYN^® (pralatrexate injection), also marketed in the U.S.; ZEVALIN^® (ibritumomab tiuxetan) Injection for Intravenous Use, for which Spectrum has worldwide marketing rights; MARQIBO^® (vinCRIStine sulfate LIPOSOME injection), for which Spectrum has worldwide marketing rights; BELEODAQ™ (belinostat) for Injection in the U.S; and EVOMELA (Captisol-Enabled™ melphalan) for injection in the U.S.

Spectrum Cayman is owned 99% by Spectrum and 1% by Spectrum Pharmaceuticals International Holdings, LLC, a Delaware limited liability company (“Spectrum Holdings”). Spectrum Holdings is the sole general partner of Spectrum Cayman and Spectrum is the sole managing member of Spectrum Holdings. Spectrum Cayman is a holding company for certain intellectual property relating to ZEVALIN^®.

The address of the principal place of business of each of the Reporting Persons is c/o Spectrum at 11500 South Eastern Avenue, Suite 240, Henderson, Nevada 89052.

During the last five years, neither of the Reporting Persons, nor any of their respective executive officers, directors, or general partners, has been convicted in a criminal proceeding (excluding traffic violations or similar misdemeanors), nor have any such persons been a party to a civil proceeding of a judicial or administrative body of competent jurisdiction as a result of which such person 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 violation with respect to such laws.

Spectrum is governed by a Board of Directors consisting of nine members, none of which individually have voting or dispositive power over the shares subject to this Statement. In accordance with the provisions of General Instruction C to Schedule 13D, information concerning the executive officers and directors of Spectrum is listed on Schedule 1 hereto and is incorporated herein by this reference.

Item 3. Source and Amount of Funds or Other Consideration.

On September 17, 2014, the Issuer entered into investment agreements (the “Investment Agreements”) with the Reporting Persons pursuant to which it issued an aggregate of 5,405,382 shares of its common stock to the Reporting Persons, as well as certain contingent rights to purchase additional shares of common stock and/or preferred stock (as described in Item 4 below). In consideration for the shares, pursuant to separate license agreements entered into with each of the Reporting Persons, the Issuer received perpetual (subject to customary termination provisions), exclusive licenses to develop and commercialize EVOMELA (Captisol-Enabled^TM melphalan) and ZEVALIN^® (ibritumomab tiuxetan) in China, including Taiwan, Hong Kong and Macau (“Greater China”).

Pursuant to the Contingent Purchase Right (as described in Item 4 below), the Reporting Persons purchased an additional 4,623,197 shares of the common stock at par value during 2016 (the “2016 Exercise”) and an additional 1,519,096 shares of common stock at par value during 2017 (the “2017 Exercise”). The 2017 Exercise resulted in the full settlement of the Contingent Purchase Right.

Item 4. Purpose of Transaction.

The Reporting Persons entered into the Investment Agreements in order to acquire shares of common stock of the Issuer for investment purposes with the goal of increasing the value of the Issuer as a result of, among other things, the Issuer’s development and commercialization of ZEVALIN^® and EVOMELA in Greater China.

Pursuant to the terms of the Investment Agreements, in addition to receiving an aggregate of 5,405,382 shares of the Issuer’s common stock at closing, the Reporting Persons received a contingent right to purchase additional shares of the Issuer’s common stock at par value in order to maintain their respective post-investment equity ownership percentages if the Issuer were to issue securities (subject to a limited exception for certain equity compensation grants) after September 17, 2014 (the “Contingent Purchase Right”). To the extent that the issuance of such common stock would require stockholder approval under NASDAQ rules, the Reporting Persons would instead be given the right to purchase shares of non-voting, non-convertible preferred stock, which cannot be converted into common stock without stockholder approval. The Contingent Purchase Right was due to expire upon the earliest of (i) the date on which the Issuer raised, in the aggregate, $50 million in net proceeds through capital raising activities, or (ii) September 17, 2019 (subject to extension in limited circumstances). The 2017 Exercise resulted in the full settlement of the Contingent Purchase Right.

Pursuant to the Investment Agreements, the Reporting Persons have the collective right to nominate one director to the Issuer’s Board of Directors (the “Board”), subject to the reasonable approval of the Board. Dr. Rajesh C. Shrotriya, the former Chairman and Chief Executive Officer of Spectrum, was nominated and appointed as a director of the Issuer effective September 22, 2014.

The foregoing summary description of the terms of the Investment Agreements does not purport to be complete, and is qualified in its entirety by the terms of the Investment Agreements filed as Exhibits 10.1 and 10.2, respectively, to the Schedule 13D filed by the Reporting Persons with the SEC on September 26, 2014, which are incorporated herein by reference.

Subject to applicable legal requirements, in addition to the arrangements described above, one or both of the Reporting Persons may also purchase additional securities of the Issuer from time to time in open market or private transactions, depending on their evaluation of the Issuer’s business, prospects and financial condition, the market for the Issuer’s securities, other developments concerning the Issuer, other opportunities available to the Reporting Persons, and general economic, money market and stock market conditions. In addition, depending upon the factors referred to above and subject to applicable legal requirements, the Reporting Persons may dispose of all or a portion of their securities of the Issuer at any time. Each of the Reporting Persons reserves the right to increase or decrease its holdings on such terms and at such times as each may decide.

Other than as described above in this Item 4, none of the Reporting Persons have any plan or proposal relating to or that would result in: (a) the acquisition by any person of additional securities of the Issuer or the disposition of securities of the Issuer; (b) an extraordinary corporate transaction, such as a merger, reorganization or liquidation, involving the Issuer or any of its subsidiaries; (c) a sale or transfer of a material amount of assets of the Issuer or any of its subsidiaries; (d) any change in the Board of Directors or management of the Issuer, including any plans or proposals to change the number or terms of directors or to fill any existing vacancies on the Board of Directors of the Issuer; (e) any material change in the present capitalization or dividend policy of the Issuer; (f) any other material change in the Issuer’s business or corporate structure; (g) any changes in the Issuer’s charter, by-laws or instruments corresponding thereto or other actions which may impede the acquisition of control of the Issuer by any person; (h) a class of securities of the Issuer being delisted from a national securities exchange or ceasing to be authorized to be quoted in an inter-dealer quotation system of a registered national securities association; (i) a class of equity securities of the Issuer becoming eligible for termination of registration pursuant to Section 12(g)(4) of the Securities Exchange Act of 1934, as amended; or (j) any action similar to those enumerated above.

Item 5. Interest in Securities of the Issuer.

(a) (b)

(c) Not applicable.

(d) To the best knowledge of the Reporting Persons, no person other than the Reporting Persons has the right to receive or the power to direct the receipt of dividends from, or the proceeds from the sale of, the common stock of the Issuer reported in this Statement.

(e) Not applicable.

Item 6. Contracts, Arrangements, Understandings or Relationships with Respect to Securities of the Issuer.

The information provided and incorporated by reference in Items 2, 3, 4, 5 and 7 is hereby incorporated by reference into this Item 6.

Consistent with the compensation programs for non-employee directors of the Issuer, Dr. Shrotriya receives compensation in the form of cash and option awards. In 2017, Dr. Shrotriya received an annual cash retainer payment of $20,000 and an annual grant of options to purchase 35,000 shares of the Issuer’s common stock at $1.01, which represented the closing price of the Issuer’s common stock on the NASDAQ Capital Market on the date of grant. The option award vested ratably quarterly to the end of one year. As of April 9, 2018, Dr. Shrotriya beneficially owned 155,000 shares of the Issuer’s common stock pursuant to options exercisable within 60 days of April 9, 2018.    

Other than as described in this Statement, to the best of the Reporting Persons’ knowledge, there are no other contracts, arrangements, understandings or relationships (legal or otherwise) among the persons named in Item 2 and between such persons and any person with respect to any securities of the Issuer.

Item 7. Material to be Filed as Exhibits.

SIGNATURE

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

SCHEDULE 1

Directors and Executive Officers of Spectrum

Set forth below are the name, business address, current principal occupation or employment and citizenship of each director and executive officer of Spectrum Pharmaceuticals, Inc.

EXHIBIT 24.1

POWER OF ATTORNEY

Each of the undersigned, Spectrum Pharmaceuticals, Inc., a Delaware corporation and Spectrum Pharmaceuticals Cayman, L.P., an Exempted Limited Partnership organized under the laws of the Cayman Islands (collectively, the “Undersigned”), hereby constitute and appoint Joseph W. Turgeon, Kurt A. Gustafson or Keith McGahan, or any of them signing individually, the Undersigned’s true and lawful attorney-in-fact to:

1. Complete and execute Forms 3, 4 and 5, and Schedules 13D and 13G, and such other forms and documents, including any amendments to any of the foregoing, as such attorney-in-fact shall in his discretion determine to be required or advisable pursuant to Section 16(a) and Section 13(d) of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), and the rules and regulations promulgated thereunder, or any successor laws and regulations, as a consequence of, or in respect of, the Undersigned’s beneficial ownership, acquisition or disposition of equity securities of CASI Pharmaceuticals, Inc., a Delaware corporation (the “Company”);

2. Execute and submit on behalf of the Undersigned a Form ID to obtain code numbers for the electronic filing of reports with the Securities and Exchange Commission, and any forms or documents necessary to update such code numbers or the related passwords;

3. Do and perform any and all acts for and on the behalf of the Undersigned which may be necessary or desirable in order to complete and execute any such forms, schedules or other documents, including any amendments thereto, and timely file such forms, schedules and other documents, including any amendments thereto, with the Securities and Exchange Commission, any securities exchange, the Financial Industry Regulatory Authority or any similar regulatory authority; and

4. Take any other action of any type whatsoever in connection with the foregoing which, in the opinion of such attorney-in-fact, may be of benefit to, in the best interest of, or legally required by, the Undersigned, it being understood that the forms, schedules and other documents executed by such attorney-in-fact on behalf of the Undersigned pursuant to this Power of Attorney shall be in such form and shall contain such information as such attorney-in-fact may approve in such attorney-in-fact’s discretion.

The Undersigned hereby grants to each such attorney-in-fact full power and authority to do and perform any and all acts and things whatsoever requisite, necessary, or proper to be done in the exercise of any of the rights and powers herein granted, as fully to all intents and purposes as the Undersigned might or could do if personally present, with full power of substitution or revocation, hereby ratifying and confirming all that such attorney-in-fact, or such attorney-in-fact’s substitute or substitutes, shall lawfully do or cause to be done by virtue of this Power of Attorney and the rights and powers herein granted. The Undersigned acknowledges that the foregoing attorneys-in-fact, in serving in such capacity at the request of the Undersigned, are not assuming any of the Undersigned’s responsibilities to comply with Sections 16 and 13(d) of the Exchange Act.

The Undersigned agrees that each such attorney-in-fact may rely entirely on information furnished orally or in writing by the Undersigned to each such attorney-in-fact. The Undersigned also agrees to indemnify and hold harmless each such attorney-in-fact against any losses, claims, damages or liabilities (or actions in these respects) that arise out of or are based on any untrue statement or omission of necessary facts in the information provided by the Undersigned to such attorney-in-fact for purposes of executing, acknowledging, delivering and filing Forms 3, 4 and 5, Schedules 13D and 13G and Form ID, including any amendments to any of the foregoing, and agrees to reimburse each such attorney-in-fact for any legal or other expenses incurred in connection with investigating or defending against any such loss, claim, damage, liability or action.

This Power of Attorney shall remain in full force and effect until the Undersigned is no longer required to file (or no longer voluntarily files) Forms 3, 4 or 5, or Schedule 13D or 13G, with respect to the Undersigned’s holdings of and transactions in securities issued by the Company, unless earlier revoked by the Undersigned in a signed writing delivered to the Company and the foregoing attorneys-in-fact.

[Signature Page Follows]

IN WITNESS WHEREOF, the Undersigned has executed this Power of Attorney as of the dates set forth below.

EXHIBIT 99.1

JOINT FILER AGREEMENT

In accordance with Rule 13d-1(k) under the Securities Exchange Act of 1934, as amended, the undersigned hereby agree that a single Schedule 13D, or any amendment thereto, relating to the equity securities of CASI Pharmaceuticals, Inc., a Delaware corporation, shall be filed on behalf of each of the undersigned and that this Agreement shall be filed as Exhibit 99.1 to such Schedule 13D.