of this Current Report on Form 8-K and Exhibit 99.1 attached hereto shall not be deemed "filed" for purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the "Exchange Act"), or otherwise subject to the liabilities of that Section, nor shall such information be deemed incorporated by reference in any filing under the Securities Act of 1933, as amended (the "Securities Act"), or the Exchange Act, except as shall be expressly set forth by specific reference in such a filing.

Chief Financial Officer — Sam Martin: Sam Martin plans to retire as Chief Financial Officer, with a transition period until March 31, 2027.

The filing describes an amendment to the equity incentive plan, not a management change.

of this Current Report on Form 8-K and Exhibit 99.1 attached hereto shall not be deemed "filed" for purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the "Exchange Act"), or otherwise subject to the liabilities of that Section, nor shall such information be deemed incorporated by reference in any filing under the Securities Act of 1933, as amended (the "Securities Act"), or the Exchange Act, except as shall be expressly set forth by specific reference in such a filing.

Other Events. On April 1, 2026, the Company issued a press release regarding the launch of the Offering. On April 1, 2026, the Company also issued a press release announcing that it had priced the Offering. Copies of the launch press release and pricing press release are filed as Exhibits 99.1 and 99.2, respectively, to this Current Report on Form 8-K and are incorporated by reference herein. Forward-Looking Statements Statements contained in this Current Report on Form 8-K regarding matters…

Entry into a Material Definitive Agreement. On April 1, 2026, Celldex Therapeutics, Inc. (the “Company”) entered into an underwriting agreement (the “Underwriting Agreement”) with Leerink Partners LLC and TD Securities (USA) LLC, as representatives of the several underwriters named therein (the “Underwriters”), relating to the offering, issuance and sale of 10,345,000 shares (the “Shares”) of the Company’s common stock, par value $0.001 (the “Common Stock”), at a price to the public of $29.00…

of this Current Report on Form 8-K and Exhibit 99.1 attached hereto shall not be deemed "filed" for purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the "Exchange Act"), or otherwise subject to the liabilities of that Section, nor shall such information be deemed incorporated by reference in any filing under the Securities Act of 1933, as amended (the "Securities Act"), or the Exchange Act, except as shall be expressly set forth by specific reference in such a filing.

of this Current Report on Form 8-K and Exhibit 99.1 attached hereto shall not be deemed "filed" for purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the "Exchange Act"), or otherwise subject to the liabilities of that Section, nor shall such information be deemed incorporated by reference in any filing under the Securities Act of 1933, as amended (the "Securities Act"), or the Exchange Act, except as shall be expressly set forth by specific reference in such a filing.

of this Current Report on Form 8-K and Exhibit 99.1 attached hereto shall not be deemed "filed" for purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the "Exchange Act"), or otherwise subject to the liabilities of that Section, nor shall such information be deemed incorporated by reference in any filing under the Securities Act of 1933, as amended (the "Securities Act"), or the Exchange Act, except as shall be expressly set forth by specific reference in such a filing.

The filing describes an amendment to the equity incentive plan, not a management change.

of this Current Report on Form 8-K and Exhibit 99.1 attached hereto shall not be deemed "filed" for purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the "Exchange Act"), or otherwise subject to the liabilities of that Section, nor shall such information be deemed incorporated by reference in any filing under the Securities Act of 1933, as amended (the "Securities Act"), or the Exchange Act, except as shall be expressly set forth by specific reference in such a filing.

of this Current Report on Form 8-K and Exhibit 99.1 attached hereto shall not be deemed "filed" for purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the "Exchange Act"), or otherwise subject to the liabilities of that Section, nor shall such information be deemed incorporated by reference in any filing under the Securities Act of 1933, as amended (the "Securities Act"), or the Exchange Act, except as shall be expressly set forth by specific reference in such a filing.

of this Current Report on Form 8-K and Exhibit 99.1 attached hereto shall not be deemed "filed" for purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the "Exchange Act"), or otherwise subject to the liabilities of that Section, nor shall such information be deemed incorporated by reference in any filing under the Securities Act of 1933, as amended (the "Securities Act"), or the Exchange Act, except as shall be expressly set forth by specific reference in such a filing.

of this Current Report on Form 8-K and Exhibit 99.1 attached hereto shall not be deemed "filed" for purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the "Exchange Act"), or otherwise subject to the liabilities of that Section, nor shall such information be deemed incorporated by reference in any filing under the Securities Act of 1933, as amended (the "Securities Act"), or the Exchange Act, except as shall be expressly set forth by specific reference in such a filing.

The filing describes an amendment to the equity incentive plan, not a management change.

of this Current Report on Form 8-K and Exhibit 99.1 attached hereto shall not be deemed "filed" for purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the "Exchange Act"), or otherwise subject to the liabilities of that Section, nor shall such information be deemed incorporated by reference in any filing under the Securities Act of 1933, as amended (the "Securities Act"), or the Exchange Act, except as shall be expressly set forth by specific reference in such a filing.

Entry into a Material Definitive Agreement. On February 29, 2024, Celldex Therapeutics, Inc. (the “Company”) entered into an underwriting agreement (the “Underwriting Agreement”) with Leerink Partners LLC and Cowen and Company, LLC (the “Representatives”), as representatives of the several underwriters named therein (the “Underwriters”), relating to the offering, issuance and sale of 8,520,000 shares (the “Shares”) of the Company’s common stock, par value $0.001 (the “Common Stock”), at a pri…

Other Events. On February 28, 2024, the Company issued a press release regarding the launch of the Offering. On February 29, 2024, the Company also issued a press release announcing that it had priced the Offering. Copies of the launch press release and pricing press release are filed as Exhibits 99.1 and 99.2, respectively, to this Current Report on Form 8-K and are incorporated by reference herein. Statements contained in this Current Report on Form 8-K regarding matters that are not histor…

of this Current Report on Form 8-K and Exhibit 99.1 attached hereto shall not be deemed "filed" for purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the "Exchange Act"), or otherwise subject to the liabilities of that Section, nor shall such information be deemed incorporated by reference in any filing under the Securities Act of 1933, as amended (the "Securities Act"), or the Exchange Act, except as shall be expressly set forth by specific reference in such a filing.

Other Events. On November 7, 2023, the Company issued a press release regarding the launch of the Offering. On November 7, 2023, the Company also issued a press release announcing that it had priced the Offering. Copies of the launch press release and pricing press release are filed as Exhibits 99.1 and 99.2, respectively, to this Current Report on Form 8-K and are incorporated by reference herein. Statements contained in this Current Report on Form 8-K regarding matters that are not historic…

Entry into a Material Definitive Agreement. On November 7, 2023, Celldex Therapeutics, Inc. (the “Company”) entered into an underwriting agreement (the “Underwriting Agreement”) with Jefferies LLC and Leerink Partners LLC (the “Representatives”), as representatives of the several underwriters named therein (the “Underwriters”), relating to the offering, issuance and sale of 7,425,000 shares (the “Shares”) of the Company’s common stock, par value $0.001 (the “Common Stock”), at a price to the…

Other Events. On November 6, 2023, Celldex Therapeutics, Inc. (the “Company”) announced topline data from the Company’s ongoing Phase 2 study of barzolvolimab in patients with chronic spontaneous urticaria (“CSU”) refractory to antihistamines, including patients who received prior biologics, which data supports further development of barzolvolimab in Phase 3 CSU studies. Treatment options for patients with CSU are limited and there are no approved therapies for patients who do not respond to…

of this Current Report on Form 8-K and Exhibit 99.1 attached hereto shall not be deemed "filed" for purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the "Exchange Act"), or otherwise subject to the liabilities of that Section, nor shall such information be deemed incorporated by reference in any filing under the Securities Act of 1933, as amended (the "Securities Act"), or the Exchange Act, except as shall be expressly set forth by specific reference in such a filing.

of this Current Report on Form 8-K and Exhibit 99.1 attached hereto shall not be deemed "filed" for purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the "Exchange Act"), or otherwise subject to the liabilities of that Section, nor shall such information be deemed incorporated by reference in any filing under the Securities Act of 1933, as amended (the "Securities Act"), or the Exchange Act, except as shall be expressly set forth by specific reference in such a filing.

of this Current Report on Form 8-K and Exhibit 99.1 attached hereto shall not be deemed "filed" for purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the "Exchange Act"), or otherwise subject to the liabilities of that Section, nor shall such information be deemed incorporated by reference in any filing under the Securities Act of 1933, as amended (the "Securities Act"), or the Exchange Act, except as shall be expressly set forth by specific reference in such a filing.