Hybridon announced the receipt of patent sublicense income from Isis Pharmaceuticals Inc. This payment is due to Hybridon from Isis as a result of license agreements recently entered into between Isis and third parties.

"We are pleased to see Hybridon's antisense chemistry being sought broadly as drug discovery aids," said Stephen Seiler, Hybridon's CEO. "Hybridon continues to use its antisense chemistry for its own drug discovery and development programs and with its collaborators."

In the Collaboration and License Agreement (the "Agreement") executed between Hybridon and Isis in May 2001, Isis licensed Hybridon's patents covering antisense chemistry and oral delivery while Hybridon retained the right to practice its licensed antisense patents for its own drug discovery and development programs and with its collaborators. Additionally, Hybridon took a license to Isis' suite of RNaseH patents.

Under the Agreement, when Isis sublicenses intellectual property to third parties, other than in a collaboration and that sublicense includes patents licensed from Hybridon, Isis must pay Hybridon a portion of the third party income. The payments received by Hybridon result from license agreements recently entered into between Isis and third parties.

As of March 4, 2003, Hybridon owned or exclusively licensed 91 U.S. patents and 79 U.S. patent applications, 143 corresponding foreign patents and over 184 corresponding foreign patent applications.