Enzon Pharmaceuticals, Inc.

	Enzon Pharmaceuticals, Inc.
	000 Xxxxx 000/000
	Xxxxxxxxxxx, XX 00000
	Phone:	000 000 0000
	Fax:	000 000-0000
	xxx.xxxxx.xxx

April 11, 2006

NatImmune A/S
Xxxxxxxxxxxx 0 xxx 0
XX-0000 Xxxxxxxxxx X
Xxxxxxx

Re:	Amendment #1 to License Agreement between NatImmune A/S (“NatImmune”) and
	Enzon Pharmaceuticals, Inc. (“Enzon”) dated September 30, 2005, as amended by
	Amendment #1 dated November 15, 2005 (the “Agreement”)

Gentlemen:

We are writing to confirm the agreement between NatImmune and Enzon that Section 2.3 of the Agreement concerning the terms for an agreement respecting the Baltic Countries, which provision was amended from “December 31, 2005” to “March 31, 2006” by Amendment #1, be further amended such that “March 31, 2006” be changed to “September 30, 2006”.

All other terms of the Agreement shall remain unchanged. Capitalized words used in this letter that are not defined in this letter shall have the meanings attributed to them in the Agreement.

Please sign below to acknowledge your agreement with the foregoing.

Yours truly,

ENZON PHARMACEUTICALS, INC.		Accepted and agreed by:
/s/ Xxxxxxxx X. Xxxxxx		NATIMMUNE A/S
Xxxxxxxx X. Xxxxxx
Vice President and General Counsel		By:	/s/ Xxxxxx Xxxxx
		Name: Xxxxxx Xxxxx
		Title: Chief Executive Officer
		By:	/s/ Xxxxx Xxxxxx Xxxxxx
		Name: Xxxxx Xxxxxx Møller
		Title: Chairman