EX-101 INSTANCE DOCUMENT

Exhibit 10.2

Confidential Materials omitted and filed separately with the
Securities and Exchange Commission. Asterisks denote omissions.

Merck KGaA . Germany . Frankfurter Str. 250 . 64293 Darmstadt

Idera Pharmaceuticals, Inc.		Date		19.05.2011
Steven J. Ritter, Ph.D., J.D.		Division/Dept.		Corp. Legal & Intel. Property / CL-S
Vice President — Intellectual Property and Contracts		Care of		Dr. Simone Heitz
167 Sidney Street		Phone		+49 61 51 72-2160
Cambridge, MA 02139		Fax		+49 61 51 72-2373
USA		E-Mail		***@***

Our license agreement dated December 18, 2007, effective February 4, 2008 (the “Agreement”)

Dear Steve,

It is recognized that Idera has met its obligations of delivering [**] Follow-on Compounds in accordance with Section 3.6 of the Agreement. Merck is actively characterizing these Follow-on Compounds toward a goal of selecting [**] for possible development. As this characterization is currently ongoing, Merck requests that Idera allow Merck to extend the period of time for selecting the Follow-on Compounds such that Merck’s right to make a selection pursuant to Section 3.6 of the Agreement would expire on [**]. This addition time will enable Merck to further characterize the Follow-on Compounds and make a more informed decision in the selection process based on additional preclinical experiments. During this additional time period, Idera’s role in Merck’s selection process is expected to be passive and no additional resources are expected to be provided by Idera under the terms of the Agreement.

If you are in agreement with the above please indicate so by returning the attached duplicate of this letter duly signed.

Very truly yours,

Merck KGaA				Agreed:
i.V.		i.V.		Idera Pharmaceuticals, Inc.
/s/ Astrid Perschl    Dr. Astrid Perschl		/s/ Simone Heitz    Dr. Simone Heitz		/s/ Louis J. Arcudi    Louis J. Arcudi, III

Merck KGaA · Germany
Frankfurter Str. 250		Corporation with General Partners		Executive Board and General Partners:
64293 Darmstadt		Commercial Register AG Darmstadt HRB 6164
Phone +49 6151 72-0		Registered Office: Darmstadt		Karl-Ludwig Kley (Chairman),
Fax +49 6151 72-2000		Chairman of the Supervisory Board:		Michael Becker, Kai Beckmann,
www.merck.de		Rolf Krebs		Stefan Oschmann, Bernd Reckmann