UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

Current Report

Pursuant to Section 13 or 15(d)

of the Securities Exchange Act of 1934

Date of Report (Date of earliest event reported): October 12, 2016

Seattle Genetics, Inc.

(Exact name of Registrant as specified in its charter)

Delaware	0-32405	91-1874389
(State or other jurisdiction of incorporation or organization)	(Commission File Number)	(I.R.S. Employer Identification No.)

21823 30^th Drive SE

Bothell, Washington 98021

(Address of principal executive offices, including zip code)

(425) 527-4000

(Registrant’s telephone number, including area code)

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

☐ Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

☐ Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

☐ Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

☐ Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Item 8.01 Other Events.

Seattle Genetics, Inc. (the “Company”) is filing this Current Report on Form 8-K to provide a copy of the legal opinion of Cooley LLP relating to the legality of the Company’s common stock, par value $0.001 per share, to be offered and sold pursuant the Company’s Registration Statement on Form S-3 (File No. 333-206846) and the related prospectus supplement, dated October 12, 2016, and filed with the U.S. Securities and Exchange Commission pursuant to Rule 424 under the Securities Act.

Item 9.01 Financial Statements and Exhibits.

(d) Exhibits.

Exhibit No.	Description
5.1	Opinion of Cooley LLP
23.1	Consent of Cooley LLP (included in Exhibit 5.1)

SIGNATURES

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

	SEATTLE GENETICS, INC.
Dated: October 12, 2016	By:	/s/ Clay B. Siegall
		Clay B. Siegall
		President and Chief Executive Officer

EXHIBIT INDEX

Exhibit No.	Description
5.1	Opinion of Cooley LLP
23.1	Consent of Cooley LLP (included in Exhibit 5.1)