As filed with the Securities and Exchange Commission on August 10, 2017

Registration No. 333-[     ]

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM S-8

REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933

CELLDEX THERAPEUTICS, INC.

(Exact name of registrant as specified in its charter)

Perryville III Building

53 Frontage Road, Suite 220

Hampton, New Jersey 08827

(908) 200-7500

(Address of principal executive offices; zip code)

Celldex Therapeutics, Inc. Amended and Restated 2004 Employee Stock Purchase Plan

(Full title of the plan)

Sam Martin

Chief Financial Officer

CELLDEX THERAPEUTICS, INC.

Perryville III Building

53 Frontage Road, Suite 220

Hampton, New Jersey 08827

(908) 200-7500

(Name, address and telephone number, including area code, of agent for service)

Copies to:

Anthony O. Pergola, Esq.

Lowenstein Sandler LLP

1251 Avenue of the Americas

New York, New York 10020

(212) 262-6700

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.

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 7(a)(2)(B) of the Securities Act. o

CALCULATION OF REGISTRATION FEE

(1)                                 This represents shares of common stock, par value $0.001 per share (“Common Stock”) which may be issued under the Celldex Therapeutics, Inc. Amended and Restated 2004 Employee Stock Purchase Plan, as amended (the “2004 Plan”).

(2)                                 In accordance with Rule 416 under the Securities Act of 1933, as amended (the “Securities Act”), this Registration Statement also covers such indeterminate number of additional shares of Common Stock as may be required pursuant to the 2004 Plan in the event of a stock dividend, reverse stock split, split-up, recapitalization, forfeiture of stock under the plan or other similar event.

(3)                                 Estimated solely for the purpose of calculating the registration fee pursuant to Rule 457(c) and (h)(1) under the Securities Act of 1933, as amended, based on the average of the high and low sales price on the NASDAQ Global Market on August 4, 2017, which is within five business days prior to the date of this registration statement.  Pursuant to General Instruction E to Form S-8, the registration fee is calculated only with respect to additional securities registered under the 2004 Plan.

EXPLANATORY NOTE

This Registration Statement is being filed by the registrant, Celldex Therapeutics, Inc. (the “Company”), for the purpose of registering an additional 200,000 shares of common stock, par value $0.001 per share (“Common Stock”), to be issued under the Celldex Therapeutics, Inc. Amended and Restated 2004 Employee Stock Purchase Plan, as amended (the “2004 Plan”), pursuant to General Instruction E on Form S-8 (Registration of Additional Securities). The contents of the original registration on Form S-8 for the 2004 Plan filed on July 23, 2004 (File No. 333-117602) are hereby incorporated by reference and made a part hereof. The stockholders of the registrant approved amending the 2004 Plan for this purpose at the annual meeting of stockholders held on June 15, 2017.

PART II

INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

Item 3. Incorporation of Certain Documents by Reference

The Securities and Exchange Commission allows us to “incorporate” into this registration statement information we file with other documents. This means that we may disclose important information to you by referring to other documents that contain that information. The information incorporated by reference is considered to be part of this registration statement, and information we file later with the Securities and Exchange Commission will automatically update and supersede this information. We incorporate by reference the documents listed below, except to the extent information in those documents is different from the information contained in this registration statement:

·                  Our Annual Report on Form 10-K for the year ended December 31, 2016, filed on March 14, 2017.

·                  Our Quarterly Report on Form 10-Q for the quarterly period ended March 31, 2017, filed on May 9, 2017, and for the quarterly period ended June 30, 2017, filed on August 8, 2017.

·                  Our Current Reports on Form 8-K filed with the Commission on March 1, 2017, March 14, 2017, May 9, 2017, June 16, 2017, July 5, 2017 and August 8, 2017 and on Form 8-K/A filed with the Commission on February 7, 2017 (in each case except to the extent furnished but not filed).

·                  The description of our Common Stock contained in its Registration Statement on Form 8-A, filed with the Commission on September 22, 1986 under Section 12 of the Securities Exchange Act of 1934, as amended, and any amendments or reports filed for the purpose of updating such description.

All documents subsequently filed by us with the Securities and Exchange Commission pursuant to Sections 13(a), 13(c), 14 or 15(d) of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), prior to the filing of a post-effective amendment to this registration statement, which indicates that all securities offered hereby have been sold or which deregisters all securities then remaining unsold, shall be deemed to be incorporated by reference in this registration statement and to be a part hereof from the date of filing of such documents.

Item 8. Exhibits

The exhibits accompanying this registration statement are listed on the accompanying exhibit index.

Item 9. 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:

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(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 this 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 Securities and Exchange Commission pursuant to Rule 424(b) promulgated under the Securities Act 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, that paragraphs (a)(1)(i) and (a)(1)(ii) do not apply if the registration statement is on Form S-8 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 Securities and Exchange Commission by the undersigned registrant pursuant to Section 13 or Section 15(d) of the Exchange Act that are incorporated by reference in 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.

(b)                                 The undersigned registrant hereby undertakes that, for purposes of determining any liability under the Securities Act, each filing of the undersigned registrant’s annual report pursuant to Section 13(a) or Section 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 Securities and Exchange Commission such indemnification is against public policy as expressed in the Securities 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 Securities 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 of 1933, the registrant certifies that it has reasonable grounds to believe that it meets all of the requirements for filing on Form S-8 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 August 10, 2017.

KNOW ALL BY THESE PRESENTS that each individual whose signature appears below constitutes and appoints Anthony S. Marucci and Sam Martin, and each of them singly, as such person’s true and lawful attorney-in-fact and agent with full power of substitution and resubstitution, for such person in such person’s name, place and stead, in any and all capacities, to sign any and all amendments (including post-effective amendments) to this Registration Statement, and to file the same, with all exhibits thereto, and all documents in connection therewith, with the Securities and Exchange Commission, granting unto each said attorney-in-fact and agent full power and authority to do and perform each and every act and thing requisite and necessary to be done in and about the premises, as fully to all intents and purposes as such person might or could do in person, hereby ratifying and confirming all that any said attorney-in-fact and agent, or any substitute or substitutes of any of them, may lawfully do or cause to be done by virtue hereof.

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EXHIBIT INDEX

* Filed herewith.

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Exhibit 5.1

Letterhead of Lowenstein Sandler LLP

August 10, 2017

Celldex Therapeutics, Inc.

Perryville III Building, 53 Frontage Road, Suite 220,

Hampton, New Jersey 08827

Re:          Registration Statement on Form S-8

Ladies and Gentlemen:

We have acted as special counsel to Celldex Therapeutics, Inc., a Delaware corporation (the “Company”), in connection with the Company’s filing on the date hereof with the Securities and Exchange Commission (the “SEC”) of a Registration Statement on Form S-8 (the “Registration Statement”) under the Securities Act of 1933, as amended (the “Securities Act”). The Registration Statement relates to the registration of an additional 200,000 shares (the “Shares”) of the Company’s common stock, par value $0.001 per share (the “Common Stock”), issuable pursuant to the Celldex Therapeutics, Inc. Amended and Restated 2004 Employee Stock Purchase Plan, as amended effective as of June 15, 2017 (the “2004 Plan”).

In connection with rendering this opinion, we have examined the 2004 Plan and the amendment thereto and such corporate records, certificates and other documents and such questions of law as we have considered necessary and appropriate for the purposes of this opinion.  In such examination, we have assumed the genuineness of all signatures, the legal capacity of all natural persons, the authenticity of all documents submitted to us as originals, the conformity of original documents of all documents submitted to us as certified, conformed or photostatic copies and the authenticity of the originals of such latter documents.

Based on the foregoing, and subject to the qualifications stated herein, we are of the opinion that the Shares, upon issuance and delivery as contemplated by the 2004 Plan, will be validly issued, fully paid and nonassessable outstanding shares of Common Stock.

The opinion expressed herein is limited to the corporate laws of the State of Delaware, as in effect on the date hereof, and we express no opinion as to the effect on the matters covered by this letter of the laws of any other jurisdiction.

We hereby consent to the filing of this opinion as an exhibit to the Registration Statement and to the references to this firm in the Registration Statement.  In giving such consent, we do not thereby admit that we are in the category of persons whose consent is required under Section 7 of the Securities Act or the rules and regulations of the Commission thereunder.

Exhibit 10.1

CELLDEX THERAPEUTICS, INC.
2004 EMPLOYEE STOCK PURCHASE PLAN
As amended and restated, effective as of June 15, 2017

1.                                      Purpose.  The purpose of the Celldex Therapeutics, Inc.  2004 Employee Stock Purchase Plan (the “Plan”) is to provide eligible employees of Celldex Therapeutics, Inc.  (the “Company”) and certain of its subsidiaries with opportunities to purchase shares of the Company’s common stock, par value $.01 per share (the “Common Stock”).  Four Hundred Thousand (400,000) shares of Common Stock in the aggregate have been approved and reserved for this purpose.  The Plan is intended to constitute an “employee stock purchase plan” within the meaning of Section 423(b) of the Internal Revenue Code of 1986, as amended (the “Code”), and shall be interpreted in accordance with that intent.

2.                                      Administration.  The Plan will be administered by the person or persons (the “Administrator”) appointed by the Company’s Board of Directors (the “Board “) for such purpose.  The Administrator has authority to make rules and regulations for the administration of the Plan, and its interpretations and decisions with regard thereto shall be final and conclusive.  No member of the Board or individual exercising administrative authority with respect to the Plan shall be liable for any action or determination made in good faith with respect to the Plan or any option granted hereunder.

3.                                      Offerings. The Company will make one or more offerings to eligible employees to purchase Common Stock under the Plan (“Offerings”).  Unless otherwise determined by the Administrator, each Offering will begin on the first business day occurring on or after each January 1 and July 1 and will end on the last business day occurring on or before the following June 30 and December 31, respectively.  The Administrator may, in its discretion, designate a different period for any Offering, provided that no Offering shall exceed 27 months in duration or overlap any other Offering.

4.                                      Eligibility.  Each individual classified as an employee (within the meaning of Section 3401(c) of the Code and the regulations thereunder) by the Company or a Designated Subsidiary (as defined in Section 12) on the Company’s or the Designated Subsidiary’s payroll records during the relevant participation period are eligible to participate in any one or more of the Offerings under the Plan, provided that as of the first day of the applicable Offering (the “Offering Date”) they are customarily employed by the Company or a Designated Subsidiary for more than 20 hours a week and more than five months in the calendar year during which the Offering Date occurs or in the calendar year immediately preceding such year, and have completed at least 60 days of employment.

5.                                      Participation.  An employee eligible on any Offering Date may participate in such Offering by submitting an enrollment form to his appropriate payroll location at least 15 business days before the Offering Date (or by such other deadline as shall be established for the Offering).  The form will (a) state a whole percentage to be deducted from his Compensation (as defined in Section 12) per pay period, (b) authorize the purchase of Common Stock for him in each Offering in accordance with the terms of the Plan and (c) specify the exact name or names

in which shares of Common Stock purchased for him are to be issued pursuant to Section 11.  An employee who does not enroll in accordance with these procedures will be deemed to have waived his right to participate.  Unless an employee files a new enrollment form or withdraws from the Plan, his deductions and purchases will continue at the same percentage of Compensation for future Offerings, provided he remains eligible.  Notwithstanding the foregoing, participation in the Plan will neither be permitted nor be denied contrary to the requirements of the Code.

6.                                      Employee Contributions.  Each eligible employee may authorize payroll deductions at a minimum of one percent (1%) up to a maximum of fifteen percent (15%) of his Compensation for each pay period.  The Company will maintain book accounts showing the amount of payroll deductions made by each participating employee for each Offering.  No interest will accrue or be paid on payroll deductions.

7.                                      Deduction Changes.  Except as may be determined by the Administrator in advance of an Offering, an employee may not increase or decrease his payroll deduction during any Offering, but may increase or decrease his payroll deduction with respect to the next Offering (subject to the limitations of Section 6) by filing a new enrollment form at least 15 business days before the next Offering Date (or by such other deadline as shall be established for the Offering).  The Administrator may, in advance of any Offering, establish rules permitting an employee to increase, decrease or terminate his payroll deduction during an Offering.

8.                                      Withdrawal.  An employee may withdraw from participation in the Plan by delivering a written notice of withdrawal to his appropriate payroll location.  The employee’s withdrawal will be effective as of the next business day.  Following an employee’s withdrawal, the Company will promptly refund to him his entire account balance under the Plan (after payment for any Common Stock purchased before the effective date of withdrawal).  Partial withdrawals are not permitted.  The employee may not begin participation again during the remainder of the Offering, but may enroll in a subsequent Offering in accordance with Section 5.

9.                                      Grant of Options.  On each Offering Date, the Company will grant to each eligible employee who is then a participant in the Plan an option (“Option”) to purchase on the last day of such Offering (the “Exercise Date”), at the Option Price hereinafter provided for, (a) a number of shares of Common Stock determined by dividing such employee’s accumulated payroll deductions on such Exercise Date by the lower of (i) 85% of the Fair Market Value of the Common Stock on the Offering Date, or (ii) 85% of the Fair Market Value of the Common Stock on the Exercise Date, or (b) such other lesser maximum number of shares as shall have been established by the Administrator in advance of the Offering; provided, however, that such Option shall be subject to the limitations set forth below.  Each employee’s Option shall be exercisable only to the extent of such employee’s accumulated payroll deductions on the Exercise Date.  The purchase price for each share purchased under each Option (the “Option Price”) will be 85% of the Fair Market Value of the Common Stock on the Offering Date or the Exercise Date, whichever is less.  In addition, no Participant may purchase more than 500 shares of Common Stock pursuant to the Plan in any calendar year, unless otherwise determined by the Board.

Notwithstanding the foregoing, no employee may be granted an option hereunder if such employee, immediately after the option was granted, would be treated as owning stock

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possessing five percent (5%) or more of the total combined voting power or value of all classes of stock of the Company or any Parent or Subsidiary (as defined in Section 12).  For purposes of the preceding sentence, the attribution rules of Section 424(d) of the Code shall apply in determining the stock ownership of an employee, and all stock which the employee has a contractual right to purchase shall be treated as stock owned by the employee.  In addition, no employee may be granted an Option which permits his rights to purchase stock under the Plan, and any other employee stock purchase plan of the Company and its Parents and Subsidiaries, to accrue at a rate which exceeds $25,000 of the fair market value of such stock (determined on the option grant date or dates) for each calendar year in which the Option is outstanding at any time.  The purpose of the limitation in the preceding sentence is to comply with Section 423(b)(8) of the Code and shall be applied taking Options into account in the order in which they were granted.

10.                               Exercise of Option and Purchase of Shares.  Each employee who continues to be a participant in the Plan on the Exercise Date shall be deemed to have exercised his Option on such date and shall acquire from the Company such number of whole shares of Common Stock reserved for the purpose of the Plan as his accumulated payroll deductions on such date will purchase at the Option Price, subject to any other limitations contained in the Plan.  Any amount remaining in an employee’s account at the end of an Offering will be refunded to the employee promptly.

11.                               Issuance of Certificates.  Certificates representing shares of Common Stock purchased under the Plan may be issued only in the name of the employee, in the name of the employee and another person of legal age as joint tenants with rights of survivorship, or in the name of a broker authorized by the employee to be his, or their, nominee for such purpose.

12.                               Definitions.

a)                                     The term “Compensation” means the amount of base pay, prior to salary reduction pursuant to either Sections 125, 132(f) or 401(k) of the Code, but excluding overtime, commissions, incentive or bonus awards, allowances and reimbursements for expenses such as relocation allowances or travel expenses, income or gains on the exercise of Company stock options, and similar items.

b)                                     The term “Designated Subsidiary” means any present or future Subsidiary (as defined below) that has been designated by the Board to participate in the Plan.  The Board may so designate any Subsidiary, or revoke any such designation, at any time and from time to time, either before or after the Plan is approved by stockholders.

c)                                      The term “Fair Market Value of the Common Stock” on any given date means the fair market value of the Common Stock determined in good faith by the Administrator; provided, however, that if the Common Stock is admitted to quotation on the National Association of Securities Dealers Automated Quotation System (“NASDAQ”), NASDAQ National System or national securities exchange, the determination shall be made by averaging the high and the low asked price on such date.  If there are no market quotations for such date, the determination shall be made by reference to the last date preceding such date for which there are market quotations.

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d)                                     The term “Parent” means a “parent corporation” with respect to the Company, as defined in Section 424(e) of the Code.

e)                                      The term “Subsidiary” means a “subsidiary corporation” with respect to the Company, as defined in Section 424 (f) of the Code.

13.                               Rights on Termination of Employment.  If a participating employee’s employment terminates for any reason before the Exercise Date for any Offering, no payroll deduction will be taken from any pay due and owing to the employee and the balance in his account will be paid to him or, in the case of his death, to his designated beneficiary as if he had withdrawn from the Plan under Section 8.  An employee will be deemed to have terminated employment, for this purpose, if the corporation that employs him, having been a Designated Subsidiary, ceases to be a Subsidiary, or if the employee is transferred to any corporation other than the Company or a Designated Subsidiary.  An employee will not be deemed to have terminated employment, for this purpose, if the employee is on an approved leave of absence for military service or sickness, or for any other purpose approved by the Company, if the employee’s right to reemployment is guaranteed either by a statute or by contract or under the policy pursuant to which the leave of absence was granted or if the Administrator otherwise provides in writing.

14.                               Special Rules.  Notwithstanding anything herein to the contrary, the Administrator may adopt special rules applicable to the employees of a particular Designated Subsidiary, whenever the Administrator determines that such rules are necessary or appropriate for the implementation of the Plan in a jurisdiction where such Designated Subsidiary has employees; provided that such rules are consistent with the requirements of Section 423(b) of the Code.  Such special rules may include (by way of example, but not by way of limitation) the establishment of a method for employees of a given Designated Subsidiary to fund the purchase of shares other than by payroll deduction, if the payroll deduction method is prohibited by local law or is otherwise impracticable.  Any special rules established pursuant to this Section 14 shall, to the extent possible, result in the employees subject to such rules having substantially the same rights as other participants in the Plan.

15.                               Optionees Not Stockholders.  Neither the granting of an Option to an employee nor the deductions from his pay shall constitute such employee a holder of the shares of Common Stock covered by an Option under the Plan until such shares have been purchased by and issued to him.

16.                               Rights Not Transferable.  Rights under the Plan are not transferable by a participating employee other than by will or the laws of descent and distribution, and are exercisable during the employee’s lifetime only by the employee.

17.                               Application of Funds.  All funds received or held by the Company under the Plan may be combined with other corporate funds and may be used for any corporate purpose.

18.                               Adjustment in Case of Changes Affecting Common Stock.  In the event of a subdivision of outstanding shares of Common Stock, or the payment of a dividend in Common Stock, the number of shares approved for the Plan, and the share limitation set forth in Section 9, shall be increased proportionately, and such other adjustment shall be made as may be deemed

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equitable by the Administrator.  In the event of any other change affecting the Common Stock, such adjustment shall be made as may be deemed equitable by the Administrator to give proper effect to such event.

19.                               Amendment of the Plan.  The Board may at any time, and from time to time, amend the Plan in any respect, except that without the approval, within 12 months of such Board action, by the stockholders, no amendment shall be made increasing the number of shares approved for the Plan or making any other change that would require stockholder approval in order for the Plan, as amended, to qualify as an “employee stock purchase plan” under Section 423(b) of the Code.

20.                               Insufficient Shares.  If the total number of shares of Common Stock that would otherwise be purchased on any Exercise Date plus the number of shares purchased under previous Offerings under the Plan exceeds the maximum number of shares issuable under the Plan, the shares then available shall be apportioned among participants in proportion to the amount of payroll deductions accumulated on behalf of each participant that would otherwise be used to purchase Common Stock on such Exercise Date.

21.                               Termination of the Plan.  The Plan may be terminated at any time by the Board.  Upon termination of the Plan, all amounts in the accounts of participating employees shall be promptly refunded.

22.                               Governmental Regulations.  The Company’s obligation to sell and deliver Common Stock under the Plan is subject to obtaining all governmental approvals required in connection with the authorization, issuance, or sale of such stock.

The Plan shall be governed by Massachusetts law except to the extent that such law is preempted by federal law.

23.                               Issuance of Shares.  Shares may be issued upon exercise of an Option from authorized but unissued Common Stock, from shares held in the treasury of the Company, or from any other proper source.

24.                               Tax Withholding.  Participation in the Plan is subject to any minimum required tax withholding on income of the participant in connection with the Plan.  Each employee agrees, by entering the Plan, that the Company and its Subsidiaries shall have the right to deduct any such taxes from any payment of any kind otherwise due to the employee, including shares issuable under the Plan.

25.                               Notification Upon Sale of Shares.  Each employee agrees, by entering the Plan, to give the Company prompt notice of any disposition of shares purchased under the Plan where such disposition occurs within two years after the date of grant of the Option pursuant to which such shares were purchased.

26.                               Effective Date and Approval of Shareholders.  The Plan was adopted by the Board of Directors on March 31, 2004 and shall take effect on the date that it is approved by the holders of a majority of the votes cast at a meeting of stockholders at which a quorum is present.

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Exhibit 23.1

CONSENT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

We hereby consent to the incorporation by reference in this Registration Statement on Form S-8 of our report dated March 14, 2017 relating to the financial statements and the effectiveness of internal control over financial reporting, which appears in Celldex Therapeutics, Inc.’s Annual Report on Form 10-K for the year ended December 31, 2016.