Filed Pursuant to Rule 424(b)(3)

Registration No. 333-198563

PROSPECTUS SUPPLEMENT NO. 1 DATED APRIL 16, 2015

TO

PROSPECTUS DATED APRIL 6, 2015

CORBUS PHARMACEUTICALS HOLDINGS, INC.

PROSPECTUS

19,470,273 Shares of Common Stock

This Prospectus Supplement No. 1 supplements the prospectus of Corbus Pharmaceuticals Holdings, Inc. (the “Company”, “we”, “us”, or “our”) dated April 6, 2015 (the “Prospectus”) with the following attached document which we filed with the Securities and Exchange Commission on April 16, 2015:

This Prospectus Supplement No. 1 should be read in conjunction with the Prospectus, which is required to be delivered with this Prospectus Supplement. This prospectus supplement updates, amends and supplements the information included in the Prospectus. If there is any inconsistency between the information in the Prospectus and this prospectus supplement, you should rely on the information in this prospectus supplement.

This prospectus supplement is not complete without, and may not be delivered or utilized except in connection with, the Prospectus, including any amendments or supplements to it.

Investing in our common stock involves a high degree of risk. Before making any investment in our common stock, you should carefully consider the risk factors for our common stock, which are described in the Prospectus, as amended or supplemented.

You should rely only on the information contained in the Prospectus, as supplemented or amended by this Prospectus Supplement No. 1 and any other prospectus supplement or amendment thereto. We have not authorized anyone to provide you with different information.

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or determined if this prospectus is truthful or complete. Any representation to the contrary is a criminal offense.

The date of this Prospectus Supplement No. 1 is April 16, 2015.

INDEX TO FILINGS

Annex A

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 OR 15(d) of The Securities Exchange Act of 1934

Date of Report (Date of earliest event reported): April 16, 2015

Corbus Pharmaceuticals Holdings, Inc.

(Exact name of registrant as specified in its charter)

100 River Ridge Drive, Norwood, MA 02062

(Address of Principal Executive Offices) (Zip Code)

Registrant’s telephone number, including area code: (617) 963-0100

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions (see General Instruction A.2. below):

Item 8.01. Other Information.

On April 16, 2015, Corbus Pharmaceuticals Holdings, Inc. (the “Company”) commenced trading on the Nasdaq Capital Market under the symbol “CRBP”. As a result of the uplisting to the Nasdaq Capital Market, the Company’s board of directors has abandoned its prior authorization for a reverse stock split.

SIGNATURES

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