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EXPLANANTORY NOTE

This registration statement contains two prospectuses:

·                  a base prospectus that covers the offering, issuance and sale by the registrant of its common stock, preferred stock, warrants, depositary shares and/or units up to a maximum aggregate offering price of $200,000,000;$250,000,000; and

·��                 an at-the-marketat the market offering prospectus covering the offering, issuance and sale by the registrant of shares of the registrant’s common stock up to a maximum aggregate offering price of $26,600,000$48,805,097 from time to time through Cantor Fitzgerald & Co. acting as agent pursuant to the terms of a sales agreement as amended, between the registrant and Cantor Fitzgerald & Co.

The base prospectus immediately follows this explanatory note. The at-the-marketspecific terms of any securities to be offered pursuant to the base prospectus will be specified in a prospectus supplement to the base prospectus. The at the market offering prospectus, or ATM prospectus, immediately follows the base prospectus.  The common stock that may be offered, issued and sold under the ATM prospectus is included in the $200,000,000$250,000,000 of securities that may be offered, issued and sold by the registrant under the base prospectus. Upon termination of the sales agreement with Cantor Fitzgerald & Co., any portion of the $48,805,097 included in the at the market offering prospectus that is not sold pursuant to the sales agreement will be available for sale in other offerings pursuant to the base prospectus, and if no shares are sold under the sales agreement, the full $250,000,000 of securities may be sold in other offerings pursuant to the base prospectus and a corresponding prospectus supplement.

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The information in this prospectus is not complete and may be changed. We may not sell these securities until the registration statement filed with the Securities and Exchange Commission is effective. This prospectus is not an offer to sell these securities and it is not soliciting an offer to buy these securities in any state where the offer or sale is not permitted.

Subject to Completion, dated December 21, 20122, 2016

PROSPECTUS

CELLDEX THERAPEUTICS, INC.

$200,000,000250,000,000

Common Stock

Preferred Stock

Warrants

Depositary Shares

Units

Celldex Therapeutics, Inc. may offer, issue and sell from time to time, together or separately, in one or more offerings, any combination of:

·                  our common stock,

·                  our preferred stock, which we may issue in one or more series,

·                  warrants,

·                  depositary shares, and

·                  units,

up to a maximum aggregate offering price of $200,000,000.$250,000,000.

This prospectus provides a general description of the securities we may offer.  Each time we sell securities, we will provide specific terms of the securities offered in a supplement to this prospectus (which includes an at-the-market offering prospectus). The prospectus supplement may also add, update or change information contained in this prospectus.  You should read this prospectus and the accompanying prospectus supplement, as well as the documents incorporated or deemed incorporated by reference in this prospectus, carefully before you make your investment decision. Our common stock is traded on the NASDAQ Global Market under the symbol “CLDX.” On December 18, 2012,November 30, 2016, the last reported sale price of our common stock on the NASDAQ Global Market was $6.64$3.81 per share. You are urged to obtain current market quotations of the common stock. Each prospectus supplement will indicate if the securities offered thereby will be listed on any securities exchange.

This prospectus may not be used to sell securities unless accompanied by a prospectus supplement.

We may offer to sell these securities on a continuous or delayed basis, through agents, dealers or underwriters, or directly to purchasers. The prospectus supplement for each offering of securities will describe in detail the plan of distribution for that offering. If our agents or any dealers or underwriters are involved in the sale of the securities, the applicable prospectus supplement will set forth the names of the agents, dealers or underwriters and any applicable commissions or discounts. Our net proceeds from the sale of securities will also be set forth in the applicable prospectus supplement. For general information about the distribution of securities offered, please see “Plan of Distribution” in this prospectus.

Investing in our securities involves risks. Before making an investment decisions, you should carefully review the information contained in this prospectus under the heading “Risk Factors” beginning on page 43 of this prospectus.

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ABOUT THIS PROSPECTUS

This prospectus is a part of a registration statement that we filed with the Securities and Exchange Commission, or the SEC, utilizing a “shelf” registration process. Under this shelf registration process, we may, from time to time, sell any combination of the securities described in this prospectus in one or more offerings.

The registration statement containing this prospectus, including the exhibits to the registration statement, provides additional information about us and the securities offered under this prospectus. You should read the registration statement and the accompanying exhibits for further information.  The registration statement, including the exhibits and the documents incorporated or deemed incorporated herein by reference, can be read and are available to the public over the Internet at the SEC’s website at http://www.sec.gov as described under the heading “Where You Can Find More Information.”

This prospectus provides you with a general description of the securities we may offer. Each time we sell securities pursuant to this prospectus, we will provide a prospectus supplement (which term includes, as applicable, the at-the-market offering prospectus filed with the registration statement of which this prospectus forms a part) containing specific information about the terms of a particular offering by us. That prospectus supplement may include a discussion of any risk factors or other special considerations that apply to those securities. The prospectus supplement may add, update or change information in this prospectus. If the information in the prospectus is inconsistent with a prospectus supplement, you should rely on the information in that prospectus supplement. You should read both this prospectus and, if applicable, any prospectus supplement. See “Where You Can Find More Information” for more information.

You should rely only on the information incorporated by reference or provided in this prospectus.prospectus or any prospectus supplement. We have not authorized any dealer, salesman or other person to give any information or to make any representation other than those contained or incorporated by reference in this prospectus or any prospectus supplement. You must not rely upon any information or representation not contained or incorporated by reference in this prospectus or any prospectus supplement. This prospectus and any prospectus supplement do not constitute an offer to sell or the solicitation of an offer to buy any securities other than the registered securities to which they relate, nor do this prospectus and any prospectus supplement constitute an offer to sell or the solicitation of an offer to buy securities in any jurisdiction to any person to whom it is unlawful to make such offer or solicitation in such jurisdiction. You should not assume that the information contained in this prospectus or any prospectus supplement is accurate on any date subsequent to the date set forth on the front of such document or that any information we have incorporated by reference is correct on any date subsequent to the date of the document incorporated by reference, even though this prospectus and any prospectus supplement is delivered or securities are sold on a later date.

Unless this prospectus indicates otherwise or the context otherwise requires, the terms “we,” “our,” “us,” “Celldex” or the “Company” as used in this prospectus refer to Celldex Therapeutics, Inc. and its subsidiaries, except that such terms refer to only Celldex Therapeutics, Inc. and not its subsidiaries in the sections entitled “Description of Common Stock,” “Description of Preferred Stock,” “Description of Warrants,” “Description of Depositary Shares,” and “Description of Units.”

PROSPECTUS SUMMARY

Company Overview

We are a biopharmaceutical company focused on the development and commercialization of several immunotherapy technologies for the treatment of cancer and other difficult-to-treat diseases. Our lead drug candidates include rindopepimut (CDX-110), an immunotherapeutic vaccine in a pivotal Phase 3 study for the treatment of front-line glioblastoma and a Phase 2 study for the treatment of recurrent glioblastoma, CDX-011, an antibody-drug conjugate which recently completed a randomized Phase 2b study for the treatment of advanced breast cancer and CDX-1127, a therapeutic human antibody in a Phase 1 study for cancer indications. We have additional clinical and preclinical programs, including CDX-1401, an APC Targeting Technology™ program, CDX-301, an immune cell mobilizing agent and dendritic cell growth factor and CDX-1135, a molecule that inhibits a part of the immune system called the complement system. Our drug candidates address market opportunities for which we believe current therapies are inadequate or non-existent.

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ABOUT THIS PROSPECTUS

This prospectus is part of a registration statement that we filed with the Securities and Exchange Commission, or SEC, utilizing a “shelf” registration process. Under the shelf registration process, we may offer and sell shares of our common stock having an aggregate offering price of up to $26,600,000$48,805,097 from time to time under this prospectus at prices and on terms to be determined by market conditions at the time of offering. This prospectus is deemed a prospectus supplement to the base prospectus contained in the registration statement of which this prospectus forms a part.

The registration statement containing this prospectus, including the exhibits to the registration statement, provides additional information about us and the securities offered under this prospectus. You should read the registration statement and the accompanying exhibits for further information.  The registration statement, including the exhibits and the documents incorporated or deemed incorporated herein by reference, can be read and are available to the public over the Internet at the SEC’s website at http://www.sec.gov as described under the heading “Where You Can Find More Information.”

This prospectus describes the specific terms of the common stock we are offering and also adds to, and updates information contained in the documents incorporated by reference into this prospectus. To the extent there is a conflict between the information contained in this prospectus, on the one hand, and the information contained in any document incorporated by reference into this prospectus that was filed with the SEC before the date of this prospectus, on the other hand, you should rely on the information in this prospectus. If any statement in one of these documents is inconsistent with a statement in another document having a later date - for example, a document incorporated by reference into this prospectus - the statement in the document having the later date modifies or supersedes the earlier statement.

You should rely only on the information contained in, or incorporated by reference into this prospectus and in any free writing prospectus that we may authorize for use in connection with this offering. We have not, and Cantor Fitzgerald & Co., or Cantor, has not, authorized any other person to provide you with different information. If anyone provides you with different or inconsistent information, you should not rely on it. We are not, and Cantor is not, making an offer to sell or soliciting an offer to buy our securities in any jurisdiction in which an offer or solicitation is not authorized or in which the person making that offer or solicitation is not qualified to do so or to anyone to whom it is unlawful to make an offer or solicitation. You should assume that the information appearing in this prospectus, the documents incorporated by reference into this prospectus, and in any free writing prospectus that we may authorize for use in connection with this offering, is accurate only as of the date of those respective documents. Our business, financial condition, results of operations and prospects may have changed since those dates. You should read this prospectus, the documents incorporated by reference into this prospectus, and any free writing prospectus that we may authorize for use in connection with this offering, in their entirety before making an investment decision. You should also read and consider the information in the documents to which we have referred you in the sections of this prospectus entitled “Where You Can Find More Information” and “Incorporation of Certain Information by Reference.”

The distribution of this prospectus and the offering of the common stock in certain jurisdictions may be restricted by law. Persons outside the United States who come into possession of this prospectus must inform themselves about, and observe any restrictions relating to, the offering of the common stock and the distribution of this prospectus outside the United States. This prospectus does not constitute, and may not be used in connection with, an offer to sell, or a solicitation of an offer to buy, any securities offered by this prospectus by any person in any jurisdiction in which it is unlawful for the person to make an offer or solicitation.

Unless this prospectus indicates otherwise or the context otherwise requires, the terms “we,” “our,” “us,” “Celldex” or the “Company” as used in this prospectus refer to Celldex Therapeutics, Inc. and its subsidiaries.

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SPECIAL NOTE REGARDING FORWARD-LOOKING STATEMENTSPROSPECTUS SUMMARY

ThisThe following summary of our business highlights some of the information contained elsewhere in or incorporated by reference into this prospectus.  Because this is only a summary, however, it does not contain all of the information that may be important to you.  You should carefully read this prospectus, including the documents that we incorporate by reference, contains forward-looking statements within the meaning of Section 27A of the Securities Act of 1933, as amended, or the Securities Act, and Section 21E of the Securities Exchange Act of 1934, as amended, or the Exchange Act. Any statements about our expectations, beliefs, plans, objectives, assumptions or future events or performance are not historical facts and may be forward-looking. These statements are often, but not always, made through the use of words or phrases such as “anticipate,” “estimate,” “plans,” “projects,” “continuing,” “ongoing,” “expects,” “management believes,” “we believe,” “we intend” and similar words or phrases. Accordingly, these statements involve estimates, assumptions and uncertainties, which could cause actual results to differ materially from those expressed in them. Any forward-looking statements are qualified in their entirety by reference to the risk factors discussed in this prospectus or discussed in documents incorporated by reference, which are described under “Incorporation of Documents by Reference” and “Where You Can Find More Information” in this prospectus.

Forward-looking statements are subject to known and unknown risks and uncertainties, which change over time, and are based on management’s expectations and assumptions at  You should also carefully consider the time the statements are made, and are not guarantees of future results. Our actual results may differ materially from those expressed or anticipated in the forward-looking statements for many reasons including the factors describedmatters discussed in the section entitledtitled “Risk Factors” in this prospectus and in any risk factors described in a supplement to this prospectus or in other filings.

You are cautioned not to place undue reliance on these forward-looking statements, which speak only as of the date on which they were made.  We undertake no obligation to publicly revise any forward-looking statement to reflect circumstances or events after the date of this prospectus or to reflect the occurrence of unanticipated events. You should, however, review the factors and risks we describe in theperiodic reports we file from time to time with the SEC after the date of this prospectus. We undertake no obligation to revise or update the forward-looking statements contained in this prospectus at any time. All forward-looking statements are qualified in their entiretyincorporated by this cautionary statement.

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GLEMBATUMUMAB VEDOTIN (CDX-011)

CDX-011 isUnder the terms of the Merger Agreement, upon consummation of the transactions contemplated by the Merger Agreement, Kolltan’s investors received, in exchange for their share and debt interests in Kolltan, an antibody-drug conjugateaggregate of 18,257,996 shares of Celldex’s common stock with a calculated value of $62.5 million, based on the average closing price of Celldex’s stock for the treatmentfive trading day period ending on October 28, 2016, the third calendar day prior to the date of patientsthe Merger Agreement, as adjusted downward pursuant to the terms of the Merger Agreement. The Merger Agreement provides that the number of shares that can be issued at the closing can be increased or decreased by no more than 5% in either direction based on the comparable average closing prices over the five trading days prior to the closing date.  Therefore, because the average closing price of Celldex’s stock over the five trading days prior to the closing date was higher than the comparable average closing prices over the five trading days prior to the date of the Merger Agreement, there was a full 5% downward adjustment in the number of shares issued at closing.  In addition, following closing, certain officers of Kolltan will receive an aggregate of 437,901 shares of Celldex’s common stock in lieu of cash severance obligations owed to them by Kolltan.  In addition, in the event that certain specified preclinical and clinical development milestones related to Kolltan’s development programs and/or Celldex’s development programs and certain commercial milestones related to Kolltan’s product candidates are achieved, Celldex will be required to pay Kolltan’s stockholders milestone payments of up to $172.5 million, which milestone payments may be made, at Celldex’s sole election, in cash, in shares of Celldex’s common stock or a combination of both, subject to NASDAQ listing requirements and provisions of the Merger Agreement.  The number of shares of Celldex common stock issued in connection with glycoprotein NMB, or GPNMB, expressing advanced, refractory breast cancer.  CDX-011 targetsa milestone payment, if any, will be determined based on the protein GPNMB, which is over expressed in a varietyaverage closing price per share of cancers, including breast cancer and melanoma.  The FDA has granted Fast Track designation to CDX-011Celldex common stock for the treatmentfive trading day period ending three calendar days prior to the achievement of advanced, refractory/resistant GPNMB-expressing breast cancer.

In December 2011,such milestone. Pursuant to applicable NASDAQ listing rules, we completed enrollmentare required to obtain stockholder approval of EMERGE, a randomized, multi-center Phase 2b studysuch issuances of CDX-011our common stock to the extent that such issuances exceed 19.9% of our common stock outstanding prior to the merger.  If we do not obtain stockholder approval of such common stock issuances, we may elect to pay the milestone consideration in 122 patientscash to maintain compliance with heavily pre-treated, advanced, GPNMB-positive breast cancer. Patients were randomized (2:1)applicable NASDAQ listing standards.  We may still decide to receive either CDX-011 or single-agent Investigator’s Choice, or IC, chemotherapy. Patients randomized to receive IC are allowed to cross over to CDX-011 following disease progression. Activity endpoints include response rate and progression-free survival.

In December 2012,pay cash even if we announced final results from the EMERGE study which suggested that CDX-011 induces significant response rates compared to currently available therapies in patient subsets with advanced, refractory breast cancers with high GPNMB expression (expression in  greater than 25% of tumor cells) and in patients with triple negative breast cancer.  The overall survival, or OS and progression free survival, or PFS, of patients treated with CDX-011 was also observed to be greatest in patients with triple negative breast cancer who also highly express GPNMB and all patients with high GPNMB expression as show below.obtain stockholder approval.

Phase 2b EMERGE Final Survival Results: Survival Benefit of CDX-011 is Greatest in Patients with Triple Negative Disease that Highly Expresses (>25%) GPNMB and All Patients with High GPNMB Expression*

*Analyses include all treated patients. Patients who initially received IC and subsequently crossed over to receive CDX-011 (n=15) are included in the PFS analysis for each treatment. These patients, with a median OS of 12.5 months (range 4.4 to 21.0 months), are assigned to the IC arm only for OS analysis.

Phase 2b EMERGE Final Overall Response Results: Activity of CDX-011 is Greatest in Patients with Triple Negative Disease that Highly Expresses (>25%) GPNMB and All Patients with High GPNMB Expression*

*Responses per RECIST 1.1; IC = Investigator’s Choice; CDX-011 arm includes 15 patients who crossed over to receive CDX-011 treatment after progression on IC. Analysis of best response excludes patients who discontinued from study without evaluable post-baseline radiographic imaging (n=16 for CDX-011 arm; n=5 for IC arm).

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THE OFFERINGThe Offering

The total number of shares of common stock to be outstanding immediately after this offering in the table above is based on 60,807,350101,248,821 shares of common stock issued and outstanding as of September 30, 2012 and assumes2016, which does not include the sale of shares having an aggregate offering price of $26,600,000 at an assumed sale price of $6.64, which was the last reported sale price of our common stock on the NASDAQ Global Market on December 18, 2012. This number excludes, all as of September 30, 2012:following:

·                  5,321,02610,150,598 shares issuable upon the exercise of outstanding stock options with a weighted-average exercise price of $5.99$11.26 per share;share as of September 30, 2016;

·                  3,641,582 shares available for future issuance under our equity compensation plans as of September 30, 2016, and

3,380,865·                  18,695,897 shares issued in connection with closing of the Kolltan acquisition on November 29, 2016.

Unless otherwise stated, all information in this prospectus:

·                  assumes no exercise of outstanding options to purchase common stock and no issuance of shares available for future issuance under our equity compensation plans; and

·                  2,875,569 shares of common stock issued since September 30, 2012 through December 18, 2012 which raised $16.6 millionreflects all currency in net proceeds.U.S. dollars.

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RISK FACTORS

InvestingAn investment in our securities involves significant risks. Before making an investment decision, youa high degree of risk.  You should carefully consider the risks and other information we include or incorporate by referencedescribed under “Risk Factors” in this prospectus and the accompanying prospectus. In particular, you should consider the risk factors under the heading “Risk Factors” included in our most recent Annual Report on Form 10-K,10-K/A for the year ended December 31, 2015, respectively, as may be revised or supplementedupdated by our subsequent Quarterly Reports on Form 10-Q or Current Reports on Form 8-K, each of which are onany other document that we subsequently file with the SECSecurities and areExchange Commission and that is incorporated herein by reference into this prospectus, as well as the risks described below and which may be amended, supplemented or superseded from time to timeall of the other information contained in this prospectus, and incorporated by other reports we file with the SECreference into this prospectus, including our financial statements and related notes, before investing in the future. Theour securities.  These risks and uncertainties we have described are not the only ones facing our company. Additional risksus and uncertainties not currently known to usthere may be additional matters that we are unaware of or that we currently deem immaterial may alsoconsider immaterial.  All of these could adversely affect our business, operations. Our business financial condition orprospects, cash flow, results of operations could be materially adversely affected by any of these risks. Theand financial condition.  In such case, the trading price of our securitiescommon stock could decline, due to any of these risks, and you maycould lose all or part of your investment. This prospectus is qualifiedinvestment in its entirety by these risk factors.our common stock.

Additional Risks Related to this Offering

We currently have no product revenue and will need to raise capital to operate our business in addition to funds we receive in this offering.

To date, we have generated no product revenue. Until, and unless, we complete clinical trials and further development, and receive approval from the FDA and other regulatory authorities for our product candidates, we cannot sell our drugs and will not have product revenue. Therefore, for the foreseeable future, we will have to fund all of our operations and development expenditures from cash on hand, equity or debt financings, licensing fees and grants.  While the funds we receive in this offering will help fund our operations, additional financing will also be required.  If we do not succeed in raising additional funds on acceptable terms, we might not be able to complete planned preclinical and clinical trials or obtain approval of any product candidates from the FDA and other regulatory authorities. In addition, we could be forced to discontinue product development, reduce or forego sales and marketing efforts, forego attractive business opportunities or curtail operations. Any additional sources of financing could involve the issuance of our equity securities, which would have a dilutive effect on our stockholders.  No assurance can be given that additional financing will be available to us when needed on acceptable terms, or at all.

Management will have broad discretion as to the use of the proceeds from this offering, and we may not use the proceeds effectively.

Because we have not designated the amount of net proceeds received by us from this offering to be used for any particular purpose, our management will have broad discretion as to the application of the net proceeds from this offering and could use them for purposes other than those contemplated at the time of the offering.  Our management may use the net proceeds for corporate purposes that may not improve our financial condition or market value.

You willmay experience immediate and substantial dilution in the book value per share of the common stock you purchase.

Because the price per share of our common stock being offered may be higher than the book value per share of our common stock, you may suffer substantial dilution in the net tangible book value of the common stock you purchase in this offering.  See the section entitled “Dilution” below for a more detailed discussion of the dilution you will incur if you purchase common stock in this offering.  In addition, we have a significant number of options and restricted stock outstanding.  If the holders of these securities exercise or convert them or become vested in them, as applicable, you may incur further dilution.

ATM -8-You may experience future dilution as a result of future equity offerings or if we issue shares to former Kolltan stockholders upon achievement of certain specified milestones.

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PLAN OF DISTRIBUTION

Amendment No. 1 to our existingWe have entered into a Controlled Equity OfferingSM sales agreement with Cantor provides for the issuanceFitzgerald & Co., or Cantor, pursuant to which we may offer and sale by ussell up to $60 million of shares of our common stock, having an aggregate offering price of up to $44,000,000$0.001 par value per share, from time to time through Cantor acting as agent. Our existingThis summary of the material provisions of the sales agreement has been filed as an exhibitdoes not purport to our Current Report on Form 8-K filed with the SEC on January 6, 2011,be a complete statement of its terms and Amendment No. 1 toconditions. A copy of the sales agreement has been filed as an exhibit to oura Current Report on Form 8-K filed withunder the SEC on September 24, 2012;Exchange Act and each is incorporated by reference ininto the registration statement of which this prospectus.prospectus is a part. See “Where You Can Find More Information” below. As of December 18, 2012,2, 2016, we had issued and sold shares of our common stock having an aggregate offering price of $17,400,000$11,194,903 pursuant to our prior registration statement on Form S-3S-3ASR (File No. 333-165899)333-192640).  Accordingly, we may issue and sell additional shares of our common stock having an aggregate offering price of up to $26,600,000$48,805,097 pursuant to this prospectus.

Upon delivery of a placement notice and subject to the terms and conditions of the sales agreement, as amended, Cantor may sell our common stock by any method permitted by law deemed to be an “at-the-market” offering,“at the market offering” as defined in Rule 415415(a)(4) promulgated under the Securities Act, including sales made directly on the NASDAQ Global Market, on any other existing trading market for our common stock or to or through a market maker. Cantor may also sell our common stock by any other method permitted by law. We may instruct Cantor not to sell common stock if the sales cannot be effected at or above the price designated by us from time to time.Act. We or Cantor may suspend or terminate the offering of our common stock upon notice and subject to other conditions.

We will pay Cantor commissions, in cash, for its services in acting as agent in theupon each sale of our common stock. Cantor will be entitledstock pursuant to compensation atthe sales agreement, a fixed commission rate ofin an amount equal to 3.0% of the aggregate gross sales price per share sold.proceeds from each sale of our common stock. Because there is no minimum offering amount required as a condition to close this offering, the actual total public offering amount, commissions and proceeds to us, if any, are not determinable at this time. We have also agreed to reimburse Cantor for certain specifieda portion of Cantor’s expenses, including thelegal fees, and disbursementsin connection with this offering up to a maximum of its legal counsel in an amount not to exceed $50,000. We estimate that the total expenses for the offering, excluding compensation and reimbursementsexpense reimbursement payable to Cantor under the terms of the sales agreement, will be approximately $69,000.$110,000.

Settlement for sales of our common stock will occur on the third business day following the date on which any sales are made, or on some other date that is agreed upon by us and Cantor in connection with a particular transaction, in return for payment of the net proceeds to us. There is no arrangement for funds to be received in an escrow, trust or similar arrangement. Sales of our common stock as contemplated in this prospectus will be settled through the facilities of The Depository Trust Company or by such other means as we and Cantor may agree upon. There is no arrangement for funds to be received in an escrow, trust or similar arrangement.

Cantor will use itsact as sales agent on a commercially reasonable efforts basis consistent with its normal trading and sales practices and trading practices, to solicit offers to purchaseapplicable state and federal laws, rules and regulations and the common stock shares under the terms and subject to the conditions set forth in the sales agreement.rules of NASDAQ. In connection with the sale of the common stock on our behalf, Cantor may, and will with respect to sales effected in an “at-the-market offering,” be deemed to be an “underwriter” within the meaning of the Securities Act and the compensation of Cantor maywill be deemed to be underwriting commissions or discounts. We have agreed to provide indemnification and contribution to Cantor against certain civil liabilities, including liabilities under the Securities Act.

The offering of our common stock pursuant to the sales agreement will terminate upon the earlier of (i) the sale of all shares of our common stock subject to the sales agreement, or (ii) termination of the sales agreement as

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LEGAL MATTERS

TheLowenstein Sandler LLP, Roseland, New Jersey, will provide us with an opinion as to the validity of the securities beingshares of common stock offered hereby will be passed upon by Lowenstein Sandler PC, Roseland, New Jersey.this prospectus.  Cantor is being represented in connection with this offering by Reed SmithCooley LLP, New York, New York.

EXPERTS

The financial statements and management’s assessment of the effectiveness of internal control over financial reporting (which is included in Management’s Report on Internal Control over Financial Reporting) incorporated in this prospectus by reference to ourthe Annual Report on Form 10-K10-K/A for the year ended December 31, 20112015 have been so incorporated in reliance on the report(s)report of PricewaterhouseCoopers LLP, an independent registered public accounting firm, given on the authority of said firm as experts in auditing and accounting.

WHERE YOU CAN FIND MORE INFORMATION

We have filed with the SEC a registration statement on Form S-3, including exhibits, under the Securities Act of which this prospectus and the accompanying prospectus form a part. This prospectus does not contain all of the information set forth in the registration statement. This prospectus contains descriptions of certain agreements or documents that are exhibits to the registration statement. The statements as to the contents of such exhibits, however, are brief descriptions and are not necessarily complete, and each statement is qualified in all respects by reference to such agreement or document. For further information about us, please refer to the registration statement and the documents incorporated by reference in this prospectus.

We file annual, quarterly and current reports, proxy statements and other information with the SEC.  Our SEC filings are availableWe have also filed a registration statement on Form S-3, including exhibits, under the Securities Act with respect to the public oversecurities offered by this prospectus.  This prospectus is a part of the Internetregistration statement but do not contain all of the information included in the registration statement or the exhibits.  You may read and copy the registration statement and any other document that we file at the SEC’s website at http://www.sec.gov. The SEC’s website contains reports, proxy statements and other information regarding issuers, such as Celldex Therapeutics, Inc., that file electronically with the SEC. You may also read and copy any document we file with the SEC at the SEC’s Public Reference Room, locatedpublic reference room at 100 F Street, N.E., Room 1580, Washington D.C. 20549.  PleaseYou can call the SEC at 1-800-SEC-0330 for further information on the operation of its Public Reference Room. We make available free of charge throughthe public reference room.  You can also find our public filings with the SEC on the Internet at a web site our Annual Report on Form 10-K, Quarterly Reports on Form 10-Q, Current Reports on Form 8-K, Proxy Statements on Schedule 14A and all amendments to those reports as soon as reasonably practicable after such material is electronically filed with or furnished tomaintained by the SEC. Our website address isSEC located at http://www.celldextherapeutics.comwww.sec.gov. Please note that our website address is provided as an inactive textual reference only. Information contained on or accessible through our website is not part of this prospectus and is therefore not incorporated by reference unless such information is otherwise specifically referenced elsewhere in this prospectus.

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PART II

INFORMATION NOT REQUIRED IN THE PROSPECTUS

Item 14.                   Other Expenses of Issuance and Distribution.

The following table sets forth the estimated costs and expenses payable by the Registrant in connection with the registration of the securities being registered under this Registration Statement. All amounts shown are estimates except the Securities and Exchange Commission registration statement filing fee:

*      Estimated                 These fees are calculated on the securities offered and the number of issuances and accordingly cannot be estimated at this time.

Item 15.Indemnification of Directors and Officers.

Celldex is a Delaware corporation. In accordance with the Delaware General Corporation Law (the “DGCL”), Article Six of the Registrant’s Third Restated Certificate of Incorporation, as amended, provides that no director of the Registrant shall be personally liable to the Registrant or its stockholders for breach of fiduciary duty as a director, except for liability (i) for any breach of the director’s duty of loyalty to Celldex or its stockholders, (ii) for acts or omissions not in good faith or which involve intentional misconduct or a knowing violation of law, (iii) under Section 174 of the DGCL, or (iv) for any transaction from which the director derived an improper personal benefit.

The DGCL permits, but does not require, a corporation to indemnify its directors, officers, employees or agents and expressly provides that the indemnification provided for under the DGCL shall not be deemed exclusive of any indemnification right under any bylaw, agreement, vote of stockholders or disinterested directors, or otherwise. The DGCL permits indemnification against expenses and certain other liabilities arising out of legal actions brought or threatened against such persons for their conduct on behalf of the corporation, provided that each such person acted in good faith and in a manner that he or she reasonably believed was in or not opposed to the corporation’s best interests and in the case of a criminal proceeding, had no reasonable cause to believe his or her conduct was unlawful. The DGCL does not allow indemnification of directors in the case of an action by or in the right of the corporation (including stockholder derivative suits) unless the directors successfully defend the action or indemnification is ordered by the court. The Amended and Restated Bylaws of Celldex (the “Bylaws”) provide for indemnification to the directors, officers, employees and agents of Celldex consistent with that authorized by the DGCL. Insofar as indemnification for liabilities arising under the Securities Act of 1933, as amended, may be permitted to directors and officers of Celldex pursuant to the foregoing provision or otherwise, Celldex has been advised that, in the opinion of the Securities and Exchange Commission, such indemnification is against public policy as expressed in the Securities Exchange Act of 1934, as amended, and is therefore, unenforceable.

Celldex currently carries a directors’ and officers’ liability insurance policy which provides for payment of expenses of Celldex’s directors and officers in connection with threatened, pending or completed actions, suits or proceedings against them in their capacities as directors and officers, in accordance with the Bylaws and the DGCL.

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Item 16.  Exhibits.

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Item 17.Undertakings.

(a)                                 The undersigned registrant hereby undertakes:

(1)   To file, during any period in which offers or sales are being made, a post-effective amendment to this registration statement:

(i)                                             To include any prospectus required by Section 10(a)(3) of the Securities Act;

(ii)                                          To reflect in the prospectus any facts or events arising after the effective date of the registration statement (or the most recent post-effective amendment thereof) which, individually or in the aggregate, represent a fundamental change in the information set forth in the registration statement. Notwithstanding the foregoing, any increase or decrease in volume of securities offered (if the total dollar value of securities offered would not exceed that which was registered) and any deviation from the low or high end of the estimated maximum offering range may be reflected in the form of prospectus filed with the Commission pursuant to Rule 424(b) if, in the aggregate, the changes in volume and price represent no more than a 20% change in the maximum aggregate offering price set forth in the “Calculation of Registration Fee” table in the effective registration statement; and

(iii)                                       To include any material information with respect to the plan of distribution not previously disclosed in the registration statement or any material change to such information in the registration statement;

provided, however, Paragraphs (a)(1)(i), (a)(1)(ii) and (a)(1)(iii) of this section do not apply if the registration statement is on Form S-3 or Form F-3 and the information required to be included in a post-effective amendment by those paragraphs is contained in reports filed with or furnished to the Commission by the registrant pursuant to section 13 or section 15(d) of the Securities Exchange Act of 1934 that are incorporated by reference in the registration statement, or is contained in a form of prospectus filed pursuant to Rule 424(b) that is part of the registration statement.

(2)                                 That, for the purpose of determining any liability under the Securities Act, each such post-effective amendment shall be deemed to be a new Registration Statement relating to the securities offered therein, and the offering of such securities at that time shall be deemed to be the initial bona fide offering thereof.

(3)   To remove from registration by means of a post-effective amendment any of the securities being registered which remain unsold at the termination of the offering.

(4)   That, for the purpose of determining liability under the Securities Act to any purchaser, (A) each prospectus filed by the registrant pursuant to Rule 424(b)(3) shall be deemed to be part of the registration statement as of the date the filed prospectus was deemed part of and included in the registration statement; and (B) each prospectus required to be filed pursuant to Rule 424(b)(2), (b)(5), or (b)(7) as part of a registration statement in reliance on Rule 430B relating to an offering made pursuant to Rule 415(a)(1)(i), (vii), or (x) for the purpose of providing the information required by section 10(a) of the Securities Act of 1933 shall be deemed to be part of and included in the registration statement as of the earlier of the date such form of prospectus is first used after effectiveness or the date of the first contract of sale of securities in the offering described in the prospectus. As provided in Rule 430B, for liability purposes of the issuer and any person that is at that date an underwriter, such date shall be deemed to be a new effective date of the registration statement relating to the securities in the registration statement to which that prospectus relates, and the offering of such securities at that time shall be deemed to be the initial bona fide offering thereof. Provided, however, that no statement made in a registration statement or prospectus that is part of the registration statement or made in a document incorporated or deemed incorporated by reference into the registration statement or prospectus that is part of the registration statement will, as to a purchaser with a time of contract of sale prior to such effective date, supersede or modify any statement that was made in the registration statement or prospectus that was part of the registration statement or made in any such document immediately prior to such effective date.

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(5)   That, for the purpose of determining liability of the registrant under the Securities Act to any purchaser in the initial distribution of the securities:

The undersigned registrant undertakes that in a primary offering of securities of the undersigned registrant pursuant to this registration statement, regardless of the underwriting method used to sell the securities to the purchaser, if the securities are offered or sold to such purchaser by means of any of the following communications, the undersigned registrant will be a seller to the purchaser and will be considered to offer or sell such securities to such purchaser:

(i)    Any preliminary prospectus or prospectus of the undersigned registrant relating to the offering required to be filed pursuant to Rule 424;

(ii)   Any free writing prospectus relating to the offering prepared by or on behalf of the undersigned registrant or used or referred to by the undersigned registrant;

(iii)  The portion of any other free writing prospectus relating to the offering containing material information about the undersigned registrant or its securities provided by or on behalf of the undersigned registrant; and

(iv)  Any other communication that is an offer in the offering made by the undersigned registrant to the purchaser.

(b)                                 The undersigned registrant hereby undertakes that, for purposes of determining any liability under the Securities Act, each filing of the registrant’s annual report pursuant to Section 13(a) or 15(d) of the Exchange Act (and, where applicable, each filing of an employee benefit plan’s annual report pursuant to Section 15(d) of the Exchange Act) that is incorporated by reference in the registration statement shall be deemed to be a new registration statement relating to the securities offered therein, and the offering of such securities at that time shall be deemed to be the initial bona fide offering thereof.

(c)                                  Insofar as indemnification for liabilities arising under the Securities Act may be permitted to directors, officers and controlling persons of the registrant pursuant to the foregoing provisions, or otherwise, the registrant has been advised that in the opinion of the Commission such indemnification is against public policy as expressed in the Act and is, therefore, unenforceable. In the event that a claim for indemnification against such liabilities (other than the payment by the registrant of expenses incurred or paid by a director, officer or controlling person of the registrant in the successful defense of any action, suit or proceeding) is asserted by such director, officer or controlling person in connection with the securities being registered, the registrant will, unless in the opinion of its counsel the matter has been settled by controlling precedent, submit to a court of appropriate jurisdiction the question whether such indemnification by it is against public policy as expressed in the Act and will be governed by the final adjudication of such issue.

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SIGNATURES

Pursuant to the requirements of the Securities Act, the Registrant certifies that it has reasonable grounds to believe that it meets all of the requirements for filing on Form S-3 and has duly caused this Registration Statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of Hampton, State of New Jersey, on December 2, 2016.

SIGNATURES AND POWER OF ATTORNEY

KNOW ALL PERSONS BY THESE PRESENTS, that each person whose signature appears below constitutes and appoints Anthony S. Marucci and Avery W. Catlin, or any one of them, as his true and lawful attorney-in-fact and agent, with full power of substitution and resubstitution, for him and in his name, place and stead, in any and all capacities, to sign any and all amendments (including pre-effective and post-effective amendments) to this registration statement on Form S-3 and any subsequent registration filed pursuant to Rule 462(b) under the Securities Act of 1933, as amended, and to file the same, with all exhibits thereto, and other documents in connection therewith, with the Securities and Exchange Commission, granting unto said attorneys-in-fact and agents, and each of them, full power and authority to do and perform each and every act and thing requisite and necessary to be done in connection therewith, as fully to all intents and purposes as he might or could do in person, hereby ratifying and confirming all that said attorneys-in-fact and agents, or any of them, or their or his substitutes or substitute, may lawfully do or cause to be done by virtue hereof.

Pursuant to the requirements of the Securities Act of 1933, as amended, this registration statement has been signed by the following persons in the capacities and on the dates indicated.

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EXHIBIT INDEX

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