Idera Pharmaceuticals Inc. has submitted to the US FDA a protocol amendment for its ongoing Phase 2 trial of HYB2055 in patients with metastatic or recurrent clear cell renal carcinoma. The company submitted the amendment in response to a higher than expected enrollment rate of treatment-naive patients in the Phase 2 trial.

According to a company release, the amendment provides for enrollment of up to 23 treatment-naive patients at each of the two dose levels being used in the trial, in addition to the 23 second-line patients per dose level described in the original study design. HYB2055 (also known as IMO-2055 or IMOxine) is Idera’s lead Toll-like Receptor 9 (TLR9) agonist for the treatment of cancer and is based on Idera’s proprietary Immune Modulatory Oligonucleotide (IMO) technology.

“Our original goal for stage A of the trial was to enroll approximately 50 patients to meet the requirement for 23 second-line patients in each of the two dose groups. We have 22 active US sites and 52 patients have been enrolled through October 14, 2005.Over 40% of these patients are treatment naive, which is markedly higher than we anticipated. As a result, we have submitted the protocol amendment and plan to continue Phase 2 stage A patient recruitment into the first half of 2006 as we seek to accrue sufficient numbers of both treatment-naïve and second-line patients to meet the statistical design. We plan to use the Phase 2 stage A data in the design of appropriate follow-up trials, said Tim Sullivan, vice president of development programmes at Idera.

HYB2055 (also known as IMO-2055 or IMOxine) is Idera’s lead Toll-like Receptor 9 (TLR9) agonist for the treatment of cancer and is based on Idera’s proprietary Immune Modulatory Oligonucleotide (IMO) technology.

Toll-like Receptors are immune system receptors that recognize elements of pathogens such as bacteria and trigger a defensive immune response. Idera’s IMO compounds mimic bacterial DNA and are specifically identified by TLR9. When TLR9 is activated, it stimulates a response that involves multiple immune system components acting to fight disease through both innate and adaptive immunity.

Idera’s IMO drug candidates have potential applications in a wide variety of diseases, including cancer, infectious diseases asthma and allergies, and can be used in combination with vaccines.